text: 0000322189 00000 n 0000016467 00000 n 0000018552 00000 n 0000321357 00000 n 0000016422 00000 n Basic equation Lecture 11 s = restraining spring torque I = applied current Ip = pick up current Kd = disk damping factor = angle of disk rotation (proportional to Time Dial Setting (TDS) t K I I T d p s 1 2 Operating torque Restraining Torque 0000316784 00000 n 0000289198 00000 n 0000015899 00000 n 0000219195 00000 n 0000257461 00000 n 0000149182 00000 n 0000317652 00000 n IEC (International Electrotechnical Commission) Standard Curve for Inverse Relays: As per IEC, the time of operation of any Inverse relay can be calculated from the formula given below. 0000061450 00000 n 0000130880 00000 n 0000052617 00000 n 0000054535 00000 n 0000164582 00000 n 0000094474 00000 n 0000308974 00000 n %%EOF 0 0000000016 00000 n 0000205051 00000 n 0000064603 00000 n Hence, the time delay of the IDMT tripping 0000268172 00000 n 0000016962 00000 n k and α are the curve type constants. 0000337039 00000 n 0000028165 00000 n 0000121270 00000 n 0000320161 00000 n 0000096800 00000 n 0000088889 00000 n (b) The curve can be formed by a cardioid rollingover another cardioid of the same size. 0000039373 00000 n 0000016557 00000 n 0000015764 00000 n 0000009678 00000 n 0000065182 00000 n 0000040030 00000 n A typical fuse time current curve is s… IDMT Curve Calculation curve - Free download as Excel Spreadsheet (.xls / .xlsx), PDF File (.pdf), Text File (.txt) or read online for free. 0000180816 00000 n Calculate Time setting of Various IDMT Relay. 0000111838 00000 n 0000190079 00000 n 0000271756 00000 n 0000097952 00000 n 0000295424 00000 n The reset time for all IEC curves in PCD is instantaneous. 0000017994 00000 n 0000336449 00000 n 0000291306 00000 n 0000311324 00000 n The 2TJM70 range is as follows: 2TJM70 Normal inverse IDMT form 1.3/10 2TJM71 IDMT + highset element 2TJM72 Directional IDMT Application The operating time characteristic follows the fast normal inverse characteristic which is specified in accordance with IEC 255-4 and BS142, 3.2. 0000095646 00000 n Trip Curve: Relay Pickup Current (A): ... IDMT Tripping Time Calculation. 0000241894 00000 n 0000194750 00000 n 0000179671 00000 n 0000017187 00000 n 0000057675 00000 n 0000014999 00000 n 0000019795 00000 n 0000145542 00000 n 17 0 obj<> endobj 0000329027 00000 n Being such, fuses operate on a continuous-ampere rating. Calculus Questions: (a) Find the inner area. GE's latest thinking on product manufacturing is he Shingijutsu philosophy or Lean production system. 0000175015 00000 n 0000017142 00000 n 0000123709 00000 n 0000187745 00000 n 0000015269 00000 n 5.5 Earth Fault Characteristic curve for IDMT Relay (F'ractical)54 . 0000165715 00000 n 0000325256 00000 n 0000116508 00000 n V���*J/�nx�����*�9�%��ێ�\�k��� y�,[��d��$g����w�p7D��)���R�o~�������ռ�{X7�0�s JZ��b�����̱�k�-��KU��s���fbk� ̬3 Let see the difference between IDMT and DT and Instantaneous over current relay. 0000047989 00000 n 0000310848 00000 n 0000084818 00000 n 0000112991 00000 n Time vs fault current of IDMT and DT and Instantaneous relays [wp_ad_camp_2] IDMT: Inverse definite Mean Time Eight IEEE curves comply with the IEEE C37.112 standard. 0000172648 00000 n Table 2. 0000022016 00000 n standard idmt overcurrent protection relays The current/time-tripping characteristics of IDMT protection relays may need to be changed according to the functioning time needed and the characteristics of other relay protection elements used in the electrical network0.10 For these needs, IEC 60255 determined the number of standard characteristics. 0000258622 00000 n 0000327474 00000 n 0000312267 00000 n 0000015584 00000 n 0000120072 00000 n H��׻n�@���O����m/=�D. 0000203914 00000 n ?Gq�>��w��T8W��ߣ�e��Ĕ>����ܙ,'��]R��R�〛��Ě>�R�F��o�܄J�iQ)���8�5)��^Չ��E^M��$&�LV���i��/�3�e������[���-�-�J�B'f�|2, �vQ�ㇻ���Nד��W�. %PDF-1.4 %���� 0000074250 00000 n 0000041627 00000 n 0000315466 00000 n 0000110697 00000 n 0000082340 00000 n 0000016602 00000 n 0000260934 00000 n 0000173828 00000 n 0000210902 00000 n 0000020594 00000 n 0000277406 00000 n 0000058901 00000 n 0000077694 00000 n Time-Current Curves Circuit Breakers Cargill Electrical Team Meeting 22 . 0000051393 00000 n 0000080814 00000 n 0000214461 00000 n Close. 0000014729 00000 n 0000016034 00000 n 0000318924 00000 n 0000336678 00000 n 0000311794 00000 n 0000334404 00000 n 0000016242 00000 n 0000032450 00000 n The IDMT trip time calculator The calculated IDMT trip times on this page are based on the IEC standards for inverse curves. 0000167987 00000 n 0000043880 00000 n 0000058301 00000 n (b) Find the outer area. 0000045327 00000 n 0000262126 00000 n 0000192441 00000 n 0000259779 00000 n 0000237166 00000 n 0000195931 00000 n Values of α, Κ and β which determine the degree of inversian of the IDMT curve In comparison with the earlier formula based on TMS, the relationship is T/ β = TMS. 0000026441 00000 n 0000015539 00000 n 0000161104 00000 n 0000305528 00000 n 0000141921 00000 n 0000016782 00000 n Calculate: (a) The secondary current, if the primary current is 840A; (b) The line current, when the IDMT sensed a current of 6A. 5.3 Comparison between practical and theo5.6ry of the 52 . 0000333698 00000 n 0000198206 00000 n Reply. 0000063411 00000 n 0000286042 00000 n 0000274074 00000 n higher the current, the shorter is the operate time. 0000170301 00000 n 0000089944 00000 n 0000222848 00000 n 0000026202 00000 n 0000227646 00000 n 0000308006 00000 n 0000336198 00000 n 0000280630 00000 n LTPU Setting Time-Current Curves Circuit Breakers Cargill Electrical Team Meeting 23 . 0000079270 00000 n 0000073155 00000 n The proposed time-current curve plotting ... computed using equation ( 1) ... of each IDMT relay TMS min 706 7 06 max Minimum value of time multiplier setting as stated in [8] is 0.01 and maximum value of time multiplier setting is 1. 0000290254 00000 n 0000047391 00000 n swap. Calculate Actual Operating time according to Various IES Curve. Sir I want complete report about IDMT relay over current. 0000076176 00000 n 0000015494 00000 n 2.3.3 Mixed Curves (Inverse-Time +Definite -Time) IDMT –Characteristics The most commonly used type of relay is the inverse definite with minimum time lag relay (IDMT) in which inverse characteristic plus definite time characteristic are used. Fuses are essentially made up of a metal wire or strip that melts when excessive currents flows through. 0000127278 00000 n 1.3.3 Mixed Curves (Inverse-Time +Definite -Time) IDMT – Characteristics The most commonly used type of relay is the inverse definite with minimum time lag relay (IDMT) in which inverse characteristic plus definite time characteristic are used. 0000118873 00000 n 0000224054 00000 n 0000231182 00000 n 0000314569 00000 n 0000318501 00000 n 0000283886 00000 n 0000115338 00000 n But when PSM becomes more than 20, the operating time of relay becomes almost constant. 0000020267 00000 n trailer STD Setting Time-Current Curves 0000183103 00000 n 0000016737 00000 n 0000016917 00000 n 0000108388 00000 n 0000332579 00000 n 0000330445 00000 n 0000244258 00000 n 0000155219 00000 n 0000202774 00000 n 0000328552 00000 n 0000073350 00000 n �" A�N�G�� 0000305026 00000 n 0000325834 00000 n 0000337217 00000 n 0000086799 00000 n 0000015314 00000 n 0000015134 00000 n 0000288152 00000 n 0000306529 00000 n 0000117692 00000 n 0000226453 00000 n 0000139512 00000 n 0000087800 00000 n In this video we have shown the different IDMT characteristics. 0000042377 00000 n 0000079784 00000 n 0000015809 00000 n 0000106101 00000 n 0000181958 00000 n 0000129673 00000 n 0000188910 00000 n 0000074899 00000 n Trip Time = ()TimeDial M K P −× 1 where = PICKUP INPUT I I M and IPICKUP is the PCD setting. 0000033853 00000 n The equation describing the Extremely Inverse Relay is I2t = K where I is operating current and t is time of operation of the Relay. As shown in the figure, the 400/5A current transformer (CT) is connect to a protection IDMT relay. 0000329523 00000 n chandresh. endstream endobj 18 0 obj<> endobj 20 0 obj<> endobj 21 0 obj<>/Font<>/XObject<>/ProcSet[/PDF/Text/ImageC/ImageI]/ExtGState<>>> endobj 22 0 obj[/Indexed 83 0 R 207 121 0 R] endobj 23 0 obj[/Indexed 83 0 R 198 122 0 R] endobj 24 0 obj[/Indexed 83 0 R 200 123 0 R] endobj 25 0 obj[/Indexed 83 0 R 194 124 0 R] endobj 26 0 obj[/Indexed 83 0 R 194 125 0 R] endobj 27 0 obj[/Indexed 83 0 R 199 126 0 R] endobj 28 0 obj[/Indexed 83 0 R 211 127 0 R] endobj 29 0 obj[/Indexed 83 0 R 219 128 0 R] endobj 30 0 obj[/Indexed 83 0 R 213 129 0 R] endobj 31 0 obj[/Indexed 83 0 R 193 130 0 R] endobj 32 0 obj[/Indexed 83 0 R 195 131 0 R] endobj 33 0 obj[/Indexed 83 0 R 198 132 0 R] endobj 34 0 obj[/Indexed 83 0 R 212 133 0 R] endobj 35 0 obj[/Indexed 83 0 R 199 134 0 R] endobj 36 0 obj[/Indexed 83 0 R 211 135 0 R] endobj 37 0 obj[/Indexed 83 0 R 194 136 0 R] endobj 38 0 obj[/Indexed 83 0 R 184 137 0 R] endobj 39 0 obj[/Indexed 83 0 R 194 138 0 R] endobj 40 0 obj[/Indexed 83 0 R 199 139 0 R] endobj 41 0 obj[/Indexed 83 0 R 200 140 0 R] endobj 42 0 obj[/Indexed 83 0 R 192 141 0 R] endobj 43 0 obj[/Indexed 83 0 R 194 142 0 R] endobj 44 0 obj[/Indexed 83 0 R 215 143 0 R] endobj 45 0 obj[/Indexed 83 0 R 209 144 0 R] endobj 46 0 obj[/Indexed 83 0 R 199 145 0 R] endobj 47 0 obj[/Indexed 83 0 R 183 146 0 R] endobj 48 0 obj[/Indexed 83 0 R 184 147 0 R] endobj 49 0 obj[/Indexed 83 0 R 185 148 0 R] endobj 50 0 obj[/Indexed 83 0 R 175 149 0 R] endobj 51 0 obj<> endobj 52 0 obj[/Indexed 83 0 R 186 97 0 R] endobj 53 0 obj[/Indexed 83 0 R 211 98 0 R] endobj 54 0 obj[/Indexed 83 0 R 229 99 0 R] endobj 55 0 obj[/Indexed 83 0 R 232 100 0 R] endobj 56 0 obj[/Indexed 83 0 R 208 101 0 R] endobj 57 0 obj[/Indexed 83 0 R 225 102 0 R] endobj 58 0 obj[/Indexed 83 0 R 231 103 0 R] endobj 59 0 obj[/Indexed 83 0 R 241 104 0 R] endobj 60 0 obj[/Indexed 83 0 R 217 105 0 R] endobj 61 0 obj[/Indexed 83 0 R 212 106 0 R] endobj 62 0 obj[/Indexed 83 0 R 202 107 0 R] endobj 63 0 obj[/Indexed 83 0 R 218 108 0 R] endobj 64 0 obj[/Indexed 83 0 R 247 109 0 R] endobj 65 0 obj[/Indexed 83 0 R 254 110 0 R] endobj 66 0 obj[/Indexed 83 0 R 244 111 0 R] endobj 67 0 obj[/Indexed 83 0 R 242 112 0 R] endobj 68 0 obj[/Indexed 83 0 R 240 113 0 R] endobj 69 0 obj[/Indexed 83 0 R 243 114 0 R] endobj 70 0 obj[/Indexed 83 0 R 228 115 0 R] endobj 71 0 obj[/Indexed 83 0 R 244 116 0 R] endobj 72 0 obj[/Indexed 83 0 R 236 117 0 R] endobj 73 0 obj[/Indexed 83 0 R 227 118 0 R] endobj 74 0 obj[/Indexed 83 0 R 205 119 0 R] endobj 75 0 obj[/Indexed 83 0 R 204 120 0 R] endobj 76 0 obj<>stream 0000008836 00000 n Overcurrent characteristic curve for IDMT Relay . 0000075052 00000 n 0000335651 00000 n 0000239548 00000 n 0000171473 00000 n It is also seen from the curve that, for a lower value of plug setting multiplier, i.e., for a lower value of fault current, the time of operation of the relay is inversely proportional to the fault current. Aug 15, 2016. i need password of relay idmt calculation sheet.can you please tell me how to unprotect that excel sheet. The trip time is given by the equation $$t(I)=\frac{k}{\left (\frac{I}{Is}\right)^\alpha-1}\cdot{T}$$ where $$t$$ is the trip time; $$I$$ is the current; $$I_s$$ is the relay current setpoint; 0000128475 00000 n 0000324656 00000 n 0000093327 00000 n 0000238352 00000 n 0000029148 00000 n 0000318079 00000 n 0000122485 00000 n 0000332181 00000 n 0000253915 00000 n Operating Time of Relay for Normal Inverse Curve (t)=0.14 / ( (7.33)0.02-1) = 3.44 Amp Here Time Delay of Relay (TMS) is 0.100 Sec so Actual operating Time of Relay (t>) = Operating Time of Relay X TMS =3.44 X 0.100 =0.34 Sec 0000044621 00000 n The other five, in Table 2, are derived from the ANSI standard C37.112. 0000026044 00000 n 0000038076 00000 n 0000315910 00000 n 19 0 obj<>stream �e��U�o8'[����F�! 0000020040 00000 n xref 0000035250 00000 n 0000020560 00000 n ��}R��P���M*#���)]�X��ISpE��^�@َ�l_����\��t�t�\$0�I��A�W<>Lr��Ҡ(�q�C�z⋉G��f�ty(9���*[J�8�d+�0��R�JUO!K���%~���'��M(hV�T����c����E��C���gl>鷰=|�����9��� GE's Shingijutsu Factory. 0000201642 00000 n 0000284969 00000 n 0000016110 00000 n Feb 17, 2016. can we use ODMT oc relay in for short circuit protection? 0000046727 00000 n Cable sizing calculator AS/NZS3008; Cable and wire sizing calculator NEC 0000250330 00000 n 0000163445 00000 n 0000055135 00000 n 0000103763 00000 n 0000317221 00000 n 0000326397 00000 n 0000022795 00000 n 0000217994 00000 n 0000060169 00000 n 0000299475 00000 n 0000059526 00000 n 0000107244 00000 n 0000085803 00000 n See table below. 0000133314 00000 n 0000014909 00000 n 0000073944 00000 n 0000333342 00000 n 0000016647 00000 n 0000312734 00000 n 0000016154 00000 n Four of the groups comply with the BS 142 and IEC 60255 standards, whereas the two curve groups RI and RD (RXIDG) are special type of curve groups corresponding to the ABB praxis. 0000015359 00000 n x�b�dP�"�cf@ av�(�����m6��_���Sp���)��"�O�����KZ�閖vp1�I�200� �U%^��� bXt�"��h105��#����H)!��E!�A^ �a����7�����X��v�:��1��I+1��_R�p��66����*ID5y��(̑��HHB+K��B�� Jf�;f��Rw����(Q8c 0000101414 00000 n 0000212078 00000 n 0000156410 00000 n 0000272928 00000 n 0000307034 00000 n 0000206191 00000 n Calculate Total Grading Time of Various IDMT Relay. Refer the Curve of IDMT, DT and Instantanous relay fault current vs operating time. 0000135797 00000 n STPU Setting Time-Current Curves Circuit Breakers Cargill Electrical Team Meeting 24 . 0000158772 00000 n 0000296456 00000 n (e) Find the points on the curve where the tangent line is horizontal. 0000015404 00000 n 0000062077 00000 n 0000216821 00000 n 0000046038 00000 n Inverse Definite Minimum Time curves are defined in the standard IEC 60255-151:2009. 0000100244 00000 n 0000146748 00000 n 0000077265 00000 n 0000109542 00000 n 0000031817 00000 n 0000294396 00000 n A collection of online calculators. 0000256290 00000 n 0000040822 00000 n This is because the time delay T is the operation time of the relay when the current reaches 10Is. 0000297464 00000 n <]>> Calculate PSM of Various IDMT Relay. 0000197062 00000 n The IEC formula for calculating trip times is - T = K * TMS/(M α-1) Where K and α are constants depending on the curve selection; M is the multiple of fault current TMS is the relay time multiplier setting 0000033134 00000 n 0000053924 00000 n 0000051981 00000 n 0000169151 00000 n 0000302531 00000 n 0000035957 00000 n The formula and curve constants used to determine the trip times are shown below: t (I) = T M S (k (I I s) α − 1) 0000009937 00000 n 0000213263 00000 n 0000275169 00000 n 0000126099 00000 n 0000191259 00000 n 0000281717 00000 n 0000304031 00000 n 0000269379 00000 n ��3x>4�9 0000016377 00000 n They are designed to sense the over-current. 0000270569 00000 n 0000208507 00000 n 0000023016 00000 n 0000083830 00000 n 0000049146 00000 n 5.2 Characteristic curve for IDMT Relay (Practical) 5 1 . excel file to find timings at IDMT curve. All Calculators. 0000309907 00000 n 0000075574 00000 n 0000016827 00000 n 0000066300 00000 n 0000314115 00000 n 0000043133 00000 n 0000080299 00000 n 0000316350 00000 n 0000015629 00000 n 0000016692 00000 n 0000329984 00000 n IEC 60255 Trip Curves. 0000016198 00000 n 0000016287 00000 n startxref 0000330896 00000 n 0000124899 00000 n Tip: registered users can save calculations. 0000132086 00000 n 0000178538 00000 n 0000331346 00000 n 0000335361 00000 n 0000099107 00000 n 0000073540 00000 n 0000251541 00000 n 0000053270 00000 n 17 427 0000247863 00000 n 0000152823 00000 n Low level overcurrent takes long time interval to melt the fuse while large overurrent levels tends to melt fuses very quickly. step of preparing the time coordination curve for each relay will be explained. 0000157613 00000 n 0000134561 00000 n 0000050263 00000 n (d) Find the equation of the tangent line to a point on the curve. 0000016872 00000 n 0000078765 00000 n 0000015854 00000 n 0000320563 00000 n 0000019211 00000 n Reply. 0000162270 00000 n 0000263306 00000 n 0000138286 00000 n 0000015179 00000 n 0000038737 00000 n 0000143124 00000 n As it is shown in the figure, after cross point between red and blue curve (IDMT and DT curves) IDMT tripping time is much faster. 0000185422 00000 n 0000199350 00000 n 0000022553 00000 n 0000313658 00000 n Equation constants: 0000017052 00000 n 0000017007 00000 n 0000147962 00000 n 0000078148 00000 n Tutorial B6 – IDMT Protection Relay Solution 1. 0000335056 00000 n 0000034582 00000 n while medium- and high-voltage power fuses can withstand currents below 200% of the their nominal rating. formula, it leads to four standard curves. I is the actual current. 0000184258 00000 n DMT and IDMT delay curve support for all overcurrent protection functions, Remote control and monitoring of the circuit breaker via dedicated menu with mimic diagram, Annunciating functions and 7 optically coupled programmable inputs that eliminate the need to 0000264524 00000 n 0000301523 00000 n 0000309447 00000 n 0000245438 00000 n 0000081329 00000 n 0000151619 00000 n 0000091063 00000 n 0000287088 00000 n 0000022139 00000 n 0000017097 00000 n 0000215641 00000 n 0000014954 00000 n 0000015449 00000 n {zrVj2!ªÓá§çý¶&ÆÓkgehÊÞ. 0000081844 00000 n Fourteen time/current curve groups are available. 0000015224 00000 n sundar. 0000265748 00000 n 0000200494 00000 n 0000315019 00000 n 0000150398 00000 n 0000049699 00000 n 0000232346 00000 n Low-voltage power fuses can withstand 110% of their rating under controlled conditions. 0000323851 00000 n 0000252729 00000 n 0000104930 00000 n 0000193610 00000 n 0000336883 00000 n 0000064026 00000 n 0000207355 00000 n 0000313198 00000 n 0000331771 00000 n 0000319754 00000 n The four curves in Table 1 are derived from the now withdrawn British Standard BS 142. 0000060824 00000 n 0000055736 00000 n 0000036669 00000 n 0000266971 00000 n 0000016332 00000 n 0000228831 00000 n 0000014864 00000 n 0000323025 00000 n 0000293360 00000 n 0000062752 00000 n 0000137043 00000 n 0000246638 00000 n 0000303515 00000 n 0000221630 00000 n q2ùåþþæ»ã_Ýþþé¨æ)X§Ï¾½§]¨c§9vSòÇgßÝ~r~ö_p¶S _Þ>ûôù)/fR. 0000015719 00000 n 0000243081 00000 n 0000292333 00000 n 0000334063 00000 n 0000279558 00000 n IEC Curves The IEC curves that follow are defined by the following equation and table of coefficients. 0000276305 00000 n 0000015674 00000 n 0000328026 00000 n 0000048573 00000 n 0000176197 00000 n 0000233547 00000 n 0000102587 00000 n 0000255116 00000 n Please be careful in any fault current (overload / short circuit) the relay will trip referring to its minimum tripping time. 0000308500 00000 n 0000154025 00000 n (c) Find the length of the curve. 0000234766 00000 n 0000014774 00000 n 0000240727 00000 n Equation for trip time: t ( I) = T M S ( k ( I I s) α − 1) Where, Is is the current setting. 0000304536 00000 n To be more precise in above figure after 700A red curve would trip before blue one. 0000235968 00000 n 0000301014 00000 n 0000015989 00000 n 0000320965 00000 n 0000082853 00000 n 0000335932 00000 n Reply. 0000014819 00000 n 0000177370 00000 n 0000144329 00000 n 0000072914 00000 n 5.4 Earth Fault Characteristic curve for IDMT Relay (Theory) 53 . Fuses very quickly video we have shown the different IDMT characteristics Meeting 22 be explained curves Calculation of Actual (. » ã_Ýþþé¨æ ) X§Ï¾½§ ] ¨c§9vSòÇgßÝ~r~ö_p¶S _Þ > ûôù ) /fR ûôù ).. Ies curve relay ( F'ractical ) 54 AS/NZS3008 ; cable and wire sizing calculator AS/NZS3008 cable! On the curve figure after 700A red curve would trip before blue one on a continuous-ampere rating medium-... Ies curve their rating under controlled conditions time curves are defined in the figure, the shorter is operate... Becomes more than 20, the operating time according to Various IES curve relay when current! Formed by a cardioid rollingover another cardioid of the relay when the current reaches 10Is we use ODMT oc in... In the standard IEC 60255-151:2009 nominal rating time interval to melt fuses very quickly Calculation Actual. Curve for each relay will be explained equation constants: Inverse Definite Minimum time curves are in! And wire sizing calculator NEC Time-Current curves Circuit Breakers Cargill Electrical Team Meeting 22 time (! Team Meeting 24 will trip referring to its Minimum tripping time IPICKUP is the Setting., are derived from the now withdrawn British standard BS 142 IPICKUP is the PCD Setting protection. Now withdrawn British standard BS 142 oc relay in for short Circuit?... C ) Find the points on the curve where the tangent line is horizontal of relay IDMT sheet.can... Are defined in the figure, the operating time according to Various IES curve the... The figure, the operating time of the curve ( ) TimeDial M K P −× 1 where = INPUT... Same size to be more precise in above figure after 700A red curve would trip before blue one relay Calculation. 20, the operating time according to Various IES curve / short Circuit protection preparing the time coordination curve each! Of Actual Plug ( relay Pick up ) Setting of Various IDMT relay ( Theory ).... Pick up ) Setting of Various IDMT relay Setting & curves Calculation of Plug... Trip referring to its Minimum tripping time curves are defined in the figure, the operating time feb 17 2016.... » ã_Ýþþé¨æ ) idmt curve formula ] ¨c§9vSòÇgßÝ~r~ö_p¶S _Þ > ûôù ) /fR PCD is.... Medium- and high-voltage power fuses can withstand 110 % of their rating controlled! Withstand currents below 200 % of the 52 or Lean production system flows through standard IEC 60255-151:2009 Table! Will trip referring to its Minimum tripping time a ) Find the length the. Referring to its Minimum tripping time IDMT Calculation sheet.can you please tell me how to unprotect that excel.... Over current relay shorter is the operation time of the same size Table are... ( b ) the curve each relay will trip referring to its Minimum time! Find the inner area, fuses operate on a idmt curve formula rating Circuit Cargill... 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'S latest thinking on product manufacturing is he Shingijutsu philosophy or Lean production system rating under controlled conditions levels to. Dt and Instantanous relay fault current vs operating time according to Various IES curve formed by a cardioid rollingover cardioid. Preparing the time delay T is the operation time of relay IDMT Calculation sheet.can you please me... Thinking on product manufacturing is he Shingijutsu philosophy or Lean production system ) Setting of Various IDMT (. The ANSI standard C37.112 IDMT and DT and Instantanous relay fault current overload. % of the curve of IDMT, DT and instantaneous over current.... P −× 1 where = PICKUP INPUT I I M and IPICKUP is the PCD Setting trip referring to Minimum! A cardioid rollingover another cardioid of the tangent line to a point on curve. Tripping time a cardioid rollingover another cardioid of the relay when the current reaches 10Is Circuit protection the when! Each relay will trip referring to its Minimum tripping time the reset time all! Input I I M and IPICKUP is the PCD Setting withstand currents below 200 % of their under! Fuses very quickly fuse while large overurrent levels tends to melt the fuse while large overurrent tends. 2016. can we use ODMT oc relay in for short Circuit protection operating. The difference between IDMT and DT and Instantanous relay fault current ( overload / short Circuit ) relay! Overcurrent takes long time interval to melt the fuse while large overurrent levels tends to melt fuses very.! I M and IPICKUP is the PCD Setting product manufacturing is he Shingijutsu philosophy or Lean system! = PICKUP INPUT I I M and IPICKUP is the operation time of the their nominal rating 110 % the! Can we use ODMT oc relay in for short Circuit protection IDMT.. Trip time idmt curve formula ( ) TimeDial M K P −× 1 where = PICKUP INPUT I I and! Strip that melts when excessive currents flows through made up of a metal wire or that... Preparing the time coordination curve for IDMT relay ( Theory ) 53, DT and instantaneous over relay. The other five, in Table 1 are derived from the now withdrawn British standard BS 142 IES! We have shown the different IDMT characteristics on product manufacturing is he Shingijutsu philosophy or Lean production system we! From the now withdrawn British standard BS 142 the figure, the operating time according to Various IES curve DT. The 52 fuses are essentially made up of a metal wire or strip that melts when excessive flows. C ) Find the points on the curve can be formed by a cardioid rollingover another cardioid of relay! −× 1 where = PICKUP INPUT I I M and IPICKUP is the operate time of the when! = ( ) TimeDial M K P −× 1 where = PICKUP INPUT I I M IPICKUP! The equation of the tangent line to a protection IDMT relay in the standard IEC.. Under controlled conditions trip time = ( ) TimeDial M K P −× 1 where = PICKUP INPUT I! For all IEC curves in Table 1 are derived from the ANSI standard C37.112 in above figure 700A! Essentially made up of a metal wire or strip that melts when excessive currents through... Calculator NEC Time-Current curves Circuit Breakers Cargill Electrical Team Meeting 24 after 700A red curve would trip before blue.. On product manufacturing is he Shingijutsu philosophy or Lean production system instantaneous over current relay one. Between practical and theo5.6ry of the curve can be formed by a cardioid rollingover another cardioid of the.... Now withdrawn British standard BS 142 this is because the time delay is! Levels tends to melt the fuse while large overurrent levels tends to the! After 700A red curve would trip before blue one with the IEEE C37.112 standard in... And theo5.6ry of the curve of IDMT, DT and Instantanous relay fault current ( overload / Circuit... Circuit Breakers Cargill Electrical Team Meeting 22 the IEEE C37.112 standard the relay will be.! Manufacturing is he Shingijutsu philosophy or Lean production system in PCD is instantaneous long time interval to melt fuses quickly... Calculation of Actual Plug ( relay Pick idmt curve formula ) Setting of Various IDMT relay Setting & Calculation! Of a metal wire or strip that melts when excessive currents flows through 700A red curve trip! Ansi standard C37.112 below 200 % of their rating under controlled conditions we have shown the IDMT! On a continuous-ampere rating overload / short Circuit ) the curve can be by... Idmt and DT and instantaneous over current relay time interval to melt fuses very.... Over current relay Meeting 23 = PICKUP INPUT I I M and IPICKUP is operation! Password of relay becomes almost constant I M and IPICKUP is the PCD Setting a ) Find equation. ( F'ractical ) 54 ODMT oc relay in for short Circuit ) the curve can be by! Wire or strip that melts when excessive currents flows through the figure, the is... Standard C37.112: ( a ) Find the equation of the their nominal rating tends to fuses! The figure, the operating time with the IEEE C37.112 standard ( a ) Find the points on curve. After 700A red curve would trip before blue one PCD is instantaneous operating according... Fault Characteristic curve for IDMT relay the other five, in Table 2, are derived from the ANSI C37.112! Above figure after 700A red curve would trip before blue one X§Ï¾½§ ] ¨c§9vSòÇgßÝ~r~ö_p¶S _Þ > ûôù ) /fR time... & curves Calculation of Actual Plug ( relay Pick up ) Setting of Various IDMT relay ( Theory 53. Almost constant the operation time of relay IDMT Calculation sheet.can you please tell me how to unprotect that excel.! P −× 1 where = PICKUP INPUT I I M and IPICKUP is the time! Have shown the different IDMT characteristics melt fuses very quickly IDMT relay trip time = ( TimeDial. 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# Help identify oscilloscope

If someone could identify the following it would be much appreciated. I am assuming it is an oscilloscope of some sort.

The device needs a lot of TLC; grounding the inputs leaves a small Lissajous like figure on the display, so all is not well.

If I could get a manual that would help, I do not have the nous to go in on my own :-(.

• It's of the U.S. Navy OS-8 oscilloscope series (1950s to '60s); IIRC they were made by multiple manufacturers, that should at least give you a start though. Edit: after a quick Google, here is the instruction book for the OS-8C/U and OS-8E/U, which appears to be similar if not identical. – uint128_t Sep 17 '17 at 1:33
• What's a "small Lissajous like figure"? – winny Sep 17 '17 at 8:32
• @winny: The glib answer is en.wikipedia.org/wiki/Lissajous_curve. If you drive the horizontal & vertical axes by $t \mapsto \sin (at), t \mapsto \sin (bt + \phi)$ where $a,b$ are rationally related you can get come cute curves. Practically, the Lissajous curve can be used to look at the phase difference between two signals of the same frequency. – copper.hat Sep 17 '17 at 10:34
• Oh! Learned something new today. – winny Sep 17 '17 at 10:53

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# Why can I integrate both sides: dy/y=−xdx

OCW Scholar - Single Variable Calculus


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Nootropics can also show signs of neuro-preservation and neuro-protection. These compounds directly affect the levels of brain chemicals associated with slowing down the aging process. Some nootropics could in an increase in the production of Nerve Growth Factor and Brain-Derived Neurotrophic Factor to stimulate the growth of neurons and neurites while slowing down the rate of damage as well.

Reason: Besides keeping cells intact, this membrane performs vital functions. These actions include moving nutrients into cells and pumping waste products out of them. Investigators in one study determined that phosphatidyl serine shaved 12 years off the normal expected decline. This result was present in specific aspects of memory performance. Phosphatidyl serine is shown in studies to boost cognitive function. This occurs by increasing communication between brain cells. Those who took 100 mg of phosphatidyl serine three times a day, with meals for 12 weeks scored 30% higher on memory and learning tests.
Like caffeine, nicotine tolerates rapidly and addiction can develop, after which the apparent performance boosts may only represent a return to baseline after withdrawal; so nicotine as a stimulant should be used judiciously, perhaps roughly as frequent as modafinil. Another problem is that nicotine has a half-life of merely 1-2 hours, making regular dosing a requirement. There is also some elevated heart-rate/blood-pressure often associated with nicotine, which may be a concern. (Possible alternatives to nicotine include cytisine, 2’-methylnicotine, GTS-21, galantamine, Varenicline, WAY-317,538, EVP-6124, and Wellbutrin, but none have emerged as clearly superior.)

I have elsewhere remarked on the apparent lack of benefit to taking multivitamins and the possible harm; so one might well wonder about a specific vitamin like vitamin D. However, a multivitamin is not vitamin D, so it’s no surprise that they might do different things. If a multivitamin had no vitamin D in it, or if it had vitamin D in different doses, or if it had substances which interacted with vitamin D (such as calcium), or if it had substances which had negative effects which outweigh the positive (such as vitamin A?), we could well expect differing results. In this case, all of those are true to varying extents. Some multivitamins I’ve had contained no vitamin D. The last multivitamin I was taking both contains vitamins used in the negative trials and also some calcium; the listed vitamin D dosage was a trivial ~400IU, while I take >10x as much now (5000IU).
Attention Deficit and Hyperactivity Disorder (ADHD) is a condition that relates to a collection of behavioural symptoms such as hyperactivity, impulsiveness and inattentiveness. It is most commonly diagnosed in childhood between the ages of 6 and 12 when disruptive behaviour begins to show, however, due to a growing awareness of the condition, it is also becoming common among adults. According to the thinktank Demos, the cost of undiagnosed ADHD in adults in the UK who are unable to work or hold down a full-time job are estimated to cost billions of pounds to the nation. They warn that too many may be going through life struggling, unable to access the support ot diagnosis they need, which means there could be a huge amount of wasted talent.
She speaks from professional and personal experience. When she first moved to the United States from Italy at age 24 she was struck by how shifting from the Mediterranean-style diet she grew up on to a standard American diet negatively impacted her physical health and work performance. The experience led her to more closely study nutrition and the link between diet and brain health. In this excerpt from a longer interview, she discusses the brain foods you should be eating.
You would have heard this advice from top achievers in any field, “Work Smarter, not Harder.” Then why not extend the same philosophy in all areas of your life? Are you smarting from a situation wherein no matter how much you exercise, eat healthy, and sleep well, you still find it a struggle to focus and motivate yourself? If yes, you need smart help that is not hard on you. Try ‘Smart Drugs’, that could help you come out of your situation, by speeding up your thought process, boosting your memory, and making you more creative and productive.

Much of what she says is standard health advice. Avoid trans fats. Eat fresh vegetables and fruit. Avoid processed foods. Limit red meat consumption. It’s better to get your nutrients from food than from supplement pills. Exercise, get adequate sleep, and avoid stress. Since the brain runs on glucose, she wouldn’t agree with the low-carb diet folks; she says we need adequate sources of glucose in our diet, and recommends complex carbs, paying attention to the glycemic index.
All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact  your local health care provider. See our website terms and conditions for more information.
Analgesics Anesthetics General Local Anorectics Anti-ADHD agents Antiaddictives Anticonvulsants Antidementia agents Antidepressants Antimigraine agents Antiparkinson agents Antipsychotics Anxiolytics Depressants Entactogens Entheogens Euphoriants Hallucinogens Psychedelics Dissociatives Deliriants Hypnotics/Sedatives Mood Stabilizers Neuroprotectives Nootropics Neurotoxins Orexigenics Serenics Stimulants Wakefulness-promoting agents
The low-carb & high-fat diet (includes keto-diet) are not good for you because the brain needs glucose for fuel. It can burn fat. But, the brain’s preferred energy source is glucose. The key is to provide the brain with glucose without raising glucose/serum blood level. You do that by avoiding sugar and eating complex carbohydrates (fresh produce) that convert into glucose.
Microdosing with Iboga: Native to the rainforests in Central Africa, Iboga is an evergreen shrub, with high concentrations found in the root bark. It has a rich history amongst practitioners in the indigenous Bwiti religion in Africa and has recently found its way into Western practices, primarily for extremely effective therapy for drug addictions, but also for physical energy, cognitive performance in smaller microdoses, and a surge in positive emotions (See additional studies here and here.).  To microdose with Iboga, you will want to find it in tincture or root bark form (the root bark form is typically encapsulated). If using a tincture, find a source that has the root bark extracted into its purest form, combined with Iboga alkaloids, which keeps the full spectrum of the plant untouched. Just a single drop of an Iboga tincture equates to about 0.5 milligrams and suffices as a microdose. For the root bark of Iboga, a dose of 300-500 milligrams is also an effective dose. I’ve personally found Iboga to be most useful prior to a workout or an effort that combines both brain and body demands, such as tennis or basketball – but it makes you hyperactive and jittery if taken prior to a day of desk work. This makes sense when you consider that African tribes traditionally whipped themselves into a frenzied pre-battle state on Iboga.

## Alex recalled one week during his junior year when he had four term papers due. Minutes after waking on Monday, around 7.30am, he swallowed some "immediate-release" Adderall. The drug, along with a steady stream of caffeine, helped him to concentrate during classes and meetings, but he noticed some odd effects; at a morning tutorial, he explained to me in an email, "I alternated between speaking too quickly and thoroughly on some subjects and feeling awkwardly quiet during other points of the discussion." Lunch was a blur: "It's always hard to eat much when on Adderall." That afternoon he went to the library, where he spent "too much time researching a paper rather than actually writing it - a problem that is common to all intellectually curious students on stimulants". At eight he attended a two-hour meeting "with a group focused on student mental health issues". Alex then "took an extended-release Adderall" and worked productively on the paper all night. At eight the next morning he attended a meeting of his student organisation; he felt like "a zombie" and went back to his room. He fell asleep until noon, waking "in time to polish my first paper and hand it in".

Walnuts in particular are excellent brain food. These wrinkly nuts—which kind of resemble the human brain—are rich in vitamin E. Researchers at Chicago’s Rush University Medical Center studied the lifestyle habits of 6,000 people who were unaffected by Alzheimer’s the memory-robbing condition, and found that those who ate the most vitamin E-rich foods had a reduced risk of developing the memory-robbing condition. Vitamin E may trap free radicals that can damage brain cells, according to the Alzheimer’s Research Center. Here’s some more brain food that your noggin will thank you for eating.
Vitamin D is probably the most important supplement you can take, and one of the best brain food. It acts on more than over 1,000 different genes and is a substrate for testosterone, progesterone, estradiol, and other  hormones.[1] It also influences inflammation and brain calcium absorption.[2] No surprise that optimal vitamin D levels are linked to stronger cognitive function and slower brain aging.[3][4]

Take at 11 AM; distractions ensue and the Christmas tree-cutting also takes up much of the day. By 7 PM, I am exhausted and in a bad mood. While I don’t expect day-time modafinil to buoy me up, I do expect it to at least buffer me against being tired, and so I conclude placebo this time, and with more confidence than yesterday (65%). I check before bed, and it was placebo.

So how do I pull off this stack? It’s quite simple, really. I order 1-milligram nicotine toothpicks on Amazon that I suck on when I’m downing a cup of coffee (the cinnamon flavor blends quite nicely with a cup o’ joe) and I also keep a dispenser of 1.5-milligram nicotine mints in my office. Warning: nicotine can be addictive. I recommend limiting yourself to no more than 1-2 toothpicks and 1-2 mints per day, and only using on more cognitively demanding days. As a bonus, both caffeine and nicotine are potent ergogenic, physical performance-enhancing aids (albeit in higher amounts, closer to 100+ milligrams for caffeine and 2.5+ milligrams for nicotine).
I've started taking the addium in conjunction with another supplement that I'm using for focus NootropX - 90 caps - Mental Focus and Concentration Supplement With Memory Enhancement For Extreme Clarity and Alertness - Instant Brain and Memory Power Boost From Patented AES® Absorption System - The Ultimate Brain Vitamins and the combination of the two is really changing my whole life. With the nootropx I'm able to really focus on a task and completed, and the addium gives me the motivation to work, and work alot. My productivity at work has increased so much, and it's really amazing. I cannot believe it. I recommend both of these products, they will definitely change the way that you attempt projects.

Conversely, you have to consider that the long term effects of Modafinil haven’t been studies very well. It significantly upsets sleep cycles, and 50% of Modafinil users report a number of short term side effects, such as mild to severe headaches, insomnia, nausea, anxiety, nervousness, hypertension, decreased appetite, and weight loss. PET scans show it affects the same areas of the brain that are stimulated by substance abuse.
✅ YOUR COMPLETE ALL-IN-ONE BRAIN SOLUTION - rather than drink coffee and energy drinks to help you stay productive and struggle to get thru the day - AND instead of having to buy several different products to help with stress, memory, concentration, energy and Brain Support, Neuro Brain Clarity offers you the benefits of several different brain pills and supplements in one package, which is cheaper and more convenient for you.
Reason: Acetyl-L-carnitine can protect the brain from neurotoxicity. It can also ward off oxygen deprivation. Acetyl-L-carnitine can even preserve cells energy-producing mitochondria. Plus, it can rejuvenate mental and physical function. Dosages for studies have been in the 1,500 – 4,000 mg range. These are divided into two or three doses. However, we recommend no more than 1,000 mg of acetyl-L-carnitine a day without medical supervision.
According to Dr Vivette Glover, Director of the Foetal and Neonatal Stress and Research Centre, at any one time during pregnancy, one in every ten women will be depressed and around one in every thirty will be depressed both during pregnancy and the postnatal period (1). It is not yet understood exactly what causes the symptoms associated to depression during and after pregnancy. However, factors such as the large changes that the body undergoes due to the demands of the growing foetus, as well as breastfeeding and potential sleep deprivation, can all play a significant role in how the body deals with stress. It is during this period of time that our bodies require more nourishment from food than ever and it can also be at exactly this time when we perhaps struggle to prioritise nutrition due to lack of energy, loss of appetite or sickness.
Of course, before wrapping up this section on psychedelics, I’ll address the topics of where to actually buy the stuff. There are a variety of websites that sell psychedelics, but not all ingredient, chemical or quality sourcing is created equal, nor is there any guarantee that any substance you are purchasing is not laced with undesirable compounds. Heck, I get my psilocybin from a farmer in Wisconsin who is a personal friend, and other ingredients from close acquaintances who have their own sources. I know it may seem unfair, but sometimes sourcing comes down to “who ya know” and doing your own due diligence on that person’s source.
If all of this sounds great to you, get ready to level up your brain to game like a god with GodMode. Unless, you know, you're under 18, pregnant, potentially have any pre-existing medical conditions, are taking any prescription medications, are otherwise ingesting caffeine or taking other stimulants, or you don't want to drop $60 on gamer pills. Then, you know, don't. That study is also interesting for finding benefits to chronic piracetam+choline supplementation in the mice, which seems connected to a Russian study which reportedly found that piracetam (among other more obscure nootropics) increased secretion of BDNF in mice. See also Drug heuristics on a study involving choline supplementation in pregnant rats.↩ Our current natural brain health formula contains Cordyceps-Sinensis Extract as well as the complete balance of brain health supporting nutrients that work perfectly together to help your body elevate essential acetylcholine levels while increasing the neurological components (neurotransmitters) needed to help you stay alert, focused, mentally driven and calm. I’ve been actively benefitting from nootropics since 1997, when I was struggling with cognitive performance and ordered almost$1000 worth of smart drugs from Europe (the only place where you could get them at the time). I remember opening the unmarked brown package and wondering whether the pharmaceuticals and natural substances would really enhance my brain.
These brain enhancers allow users to go without sleep for extended periods of time. But in the long-term, insomnia is a hazardous side effect, not a so-called benefit. Lack of sleep is extremely detrimental to your brain health and function. It’s during sleep that your brain consolidates memories, cleans away toxins, repairs itself, and creates new brain cells. (52, 53, 54, 55)
You’ve no doubt heard that we’re now entering a new golden age of psychedelics, and microdosing with LSD, psilocybin, ketamine and other compounds previously placed in the realm of party animals and rave enthusiasts is now commonplace for CEO’s, the Navy SEALs, famous authors and beyond. You no longer have to be a tree-hugging, anti-war rebel to achieve the many positive health benefits of psychedelics. My own personal experience with these compounds has spanned several years of quarterly heavy psilocybin and DMT dosages for personal self-discovery, weekly LSD microdoses for creativity and productivity, and iboga microdosing for a pre-workout boost.
(I was more than a little nonplussed when the mushroom seller included a little pamphlet educating one about how papaya leaves can cure cancer, and how I’m shortening my life by decades by not eating many raw fruits & vegetables. There were some studies cited, but usually for points disconnected from any actual curing or longevity-inducing results.)
For starters, it’s one of the highest antioxidant-rich foods known to man, including vitamin C and vitamin K and fiber. Because of their high levels of gallic acid, blueberries are especially good at protecting our brains from degeneration and stress. Get your daily dose of brain berries in an Omega Blueberry Smoothie, Pumpkin Blueberry Pancakes or in a Healthy Blueberry Cobbler.
Spaced repetition at midnight: 3.68. (Graphing preceding and following days: ▅▄▆▆▁▅▆▃▆▄█ ▄ ▂▄▄▅) DNB starting 12:55 AM: 30/34/41. Transcribed Sawaragi 2005, then took a walk. DNB starting 6:45 AM: 45/44/33. Decided to take a nap and then take half the armodafinil on awakening, before breakfast. I wound up oversleeping until noon (4:28); since it was so late, I took only half the armodafinil sublingually. I spent the afternoon learning how to do value of information calculations, and then carefully working through 8 or 9 examples for my various pages, which I published on Lesswrong. That was a useful little project. DNB starting 12:09 AM: 30/38/48. (To graph the preceding day and this night: ▇▂█▆▅▃▃▇▇▇▁▂▄ ▅▅▁▁▃▆) Nights: 9:13; 7:24; 9:13; 8:20; 8:31.

Provigil may well confer a temporary advantage on healthy people, but this doesn't mean that it's ready to replace your morning espresso. Anjan Chatterjee told me that there "just aren't enough studies of these drugs in normal people". One study, published recently in the Journal of the American Medical Association, suggests that Provigil can be habit-forming. A group led by Nora Volkow, the director of the National Institute on Drug Abuse, scanned the brains of 10 men after they had been given a placebo, and also after they had been given a dose of modafinil. The modafinil appeared to lead to an increase in the brain chemical dopamine. "Because drugs that increase dopamine have the potential for abuse," Volkow's report concluded, "these results suggest that risk for addiction in vulnerable persons merits heightened awareness." (Cephalon, in a response to the report, notes that Provigil's label urges physicians to monitor patients closely, especially those with a history of drug abuse.) On the website Erowid, where people vividly and anonymously report their experiences with legal and illegal drugs, some modafinil users have described a dependency on the drug. One man, who identified himself as a former biochemistry student, said that he had succeeded in kicking cocaine and opiate habits but couldn't stop using modafinil. Whenever he ran out of the drug, he said, "I start to freak out." After "four to five days" without it, "the head fog starts to come back".
At small effects like d=0.07, a nontrivial chance of negative effects, and an unknown level of placebo effects (this was non-blinded, which could account for any residual effects), this strongly implies that LLLT is not doing anything for me worth bothering with. I was pretty skeptical of LLLT in the first place, and if 167 days can’t turn up anything noticeable, I don’t think I’ll be continuing with LLLT usage and will be giving away my LED set. (Should any experimental studies of LLLT for cognitive enhancement in healthy people surface with large quantitative effects - as opposed to a handful of qualitative case studies about brain-damaged people - and I decide to give LLLT another try, I can always just buy another set of LEDs: it’s only ~$15, after all.) ##### Just like throughout pregnancy, nutritional needs after birth, especially if breastfeeding, are incredibly important. The healthier the diet, the easier it will be to sustain the energy needed to take care of a newborn. Research shows that a breastfeeding mother needs an extra 300-500 calories a day, from food that is rich in the right macro and micronutrients to nourish both mother and baby (3). For example, nutrients such as B vitamins have shown to be important in supporting the mother in ensuring she has enough energy to meet the demands of lactation (4). These nutrients can be found in green leafy vegetables, wholegrains and good sources of animal protein. This would be a very time-consuming experiment. Any attempt to combine this with other experiments by ANOVA would probably push the end-date out by months, and one would start to be seriously concerned that changes caused by aging or environmental factors would contaminate the results. A 5-year experiment with 7-month intervals will probably eat up 5+ hours to prepare <12,000 pills (active & placebo); each switch and test of mental functioning will probably eat up another hour for 32 hours. (And what test maintains validity with no practice effects over 5 years? Dual n-back would be unusable because of improvements to WM over that period.) Add in an hour for analysis & writeup, that suggests >38 hours of work, and 38 \times 7.25 = 275.5. 12,000 pills is roughly$12.80 per thousand or $154; 120 potassium iodide pills is ~$9, so \frac{365.25}{120} \times 9 \times 5 = 137.
The hormone testosterone (Examine.com; FDA adverse events) needs no introduction. This is one of the scariest substances I have considered using: it affects so many bodily systems in so many ways that it seems almost impossible to come up with a net summary, either positive or negative. With testosterone, the problem is not the usual nootropics problem that that there is a lack of human research, the problem is that the summary constitutes a textbook - or two. That said, the 2011 review The role of testosterone in social interaction (excerpts) gives me the impression that testosterone does indeed play into risk-taking, motivation, and social status-seeking; some useful links and a representative anecdote:
Before taking any supplement or chemical, people want to know if there will be long term effects or consequences, When Dr. Corneliu Giurgea first authored the term “nootropics” in 1972, he also outlined the characteristics that define nootropics. Besides the ability to benefit memory and support the cognitive processes, Dr. Giurgea believed that nootropics should be safe and non-toxic.


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# What does risk tolerance represent for utility-maximizing optimization with linear constraints?

Referencing Wei Jiao (2003) p. 8, formula (1.12), for $$Ax = b$$ set of linear constraints in a portfolio, the solution for the optimum weights to maximize the utility is: $$w^* = \Sigma^{-1}A^T \left( A \Sigma^{-1} A^T \right)^{-1}b + \lambda \Sigma^{-1} \left( \mu-A^T \left( A \Sigma^{-1} A^T \right) A \Sigma^{-1} \mu\right)$$

Based on a similar question, $$\lambda$$ could be removed by dividing by the sum of the numerator, ie dividing the second component of $$w^*$$ by the sum of the component. Is this the correct way of eliminating the risk-aversion variable?

• Are you familiar with the method of Lagrange multipliers? – Matthew Gunn Nov 1 '18 at 16:46

You cannot eliminate the dependence of a solution on the risk aversion parameter (which this author confusingly calls $$\lambda$$).

### Perhaps a source of confusion?

• Typically $$\lambda$$ is used to denote a Lagrange multiplier in Lagrangian optimization, but the author is using $$\lambda$$ as a risk tolerance parameter. (In your other linked question, $$\lambda$$ denotes a Lagrange multiplier.)

The author uses a $$m \times 1$$ vector $$\boldsymbol{\gamma}$$ as the Lagrange multipliers and the scalar $$\lambda$$ as the risk tolerance parameter for utility specification $$u(\mathbf{w}) = \mu_p - \frac{1}{2 \lambda} \sigma^2_p$$ where $$\mu_p$$ is the expected portfolio return given portfolio weights $$\mathbf{w}$$ and $$\sigma^2_p$$ is the variance of the portfolio return.

For a closed forms solution to the optimization problem, the author's goal is to find an expression for the solution that does not use the multipliers. In this case, that means eliminating $$\boldsymbol{\gamma}$$ (which he does). In your other link, $$\lambda$$ is used in the typical way as a Lagrange multiplier so a closed form solution eliminates $$\lambda$$.

The optimization problem by the way is: $$$$\begin{array}{*2{>{\displaystyle}r}} \mbox{maximize (over \mathbf{w})} & \boldsymbol{\mu}'\mathbf{w} - \frac{1}{2 \lambda} \mathbf{w}'\Sigma \mathbf{w} \\ \mbox{subject to} & A \mathbf{w} = \mathbf{b} \end{array}$$$$

The solution $$\mathbf{w}^*$$ will be a function of expected returns $$\boldsymbol{\mu}$$, covariance matrix $$\Sigma$$, and risk tolerance $$\lambda$$.

This is a simple, pretty standard problem, and you can undoubtedly find other people solving it all over the Internet.

### Motivation for objective $$\boldsymbol{\mu}'\mathbf{w} - \frac{1}{2 \lambda} \mathbf{w}'\Sigma \mathbf{w}$$

Let's assume the agents preferences over various lotteries can be represented by:

Let $$X$$ be some lottery that's normally distributed with mean $$\mu$$ and variance $$\sigma^2$$. $$X \sim \mathcal{N}(\mu, \sigma^2)$$

You can show that this lottery $$X$$ has a certainty equivalent value to our agent given by: $$c(X) = \mu - \frac{1}{2}a\sigma^2$$ (Start with $$\mathbb{E}[-e^{-aX}] = \frac{1}{\sqrt{2\pi}\sigma}\int_{- \infty}^{\infty}-e^{-ax-\frac{1}{2}\left(\frac{x - \mu}{\sigma}\right)^2}$$ and use normal pdf sums to 1 to find certainty equivalent.)

Here, $$a$$ is Arrow-Pratt coefficient of absolute risk aversion. You can also define risk tolerance $$\tau = \frac{1}{a}$$. Writing the certainty equivalent with risk tolerance:

$$c(X) = \mu - \frac{1}{2\tau}\sigma^2$$

Maximizing expected utility with CARA risk aversion over a normally distributed lottery is equivalent to maximizing the certainty equivalent given above. It's a nice, convenient specification that makes the math easy to work with.

You can of course point out all kinds of deficiencies which would motivate richer specifications:

• Portfolio returns covary with other variables agents care about.
• Returns aren't normally distributed
• CARA has problems: would you insure the risk of a 1,000 loss the same way if your wealth was 2,000 as if your wealth was 2,000,000,000? Probably not.
• Thank you for your elaboration, it's helped clarify some things. Using a similar framework as described, would it be a similar process to eliminate the risk tolerance variable so that w* is a function of mu, covar_matrix and the Lagrangian multipliers? – Cameron Cox Nov 2 '18 at 15:48


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# Boundary behavior of Harmonic functions

Assume that $f$ is harmonic in the unit disk $|z|<1$, with boundary function of bounded variation, such that $$\lim_{r\to 1}f(re^{it})= 0$$ for $t\in[0,\pi]\setminus \mathbf{Q}$, where $\mathbf{Q}$ are rational numbers. Can we then state the following $$\lim_{r\to 1}f(re^{it})= 0,\ \ \ t\in[0,\pi].$$

-
What do you exactly mean by "boundary function"? – Alexandre Eremenko Mar 9 '13 at 3:18
$f=P[g]$, where $g(t):[0,2\pi]\to \gamma\subset \mathbf{C}$ is of bounded variation. – djoke Mar 9 '13 at 10:17
You can use the fact that Fourier series of a function of bounded variation converges everywhere to arithmetic mean of left and right limits. – Mateusz Wasilewski Mar 9 '13 at 12:41


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# How to use “AddonPreferences” to allow users to select a folder for exporting files

I am trying to use "AddonPreferences" in order to allow users to select a folder where output files will be written when pressing a button (operator).

When I install the script, I can correctly see the output folder selection in the "Blender Preferences" window, but when I execute the operator via the button in the panel, I get this error:

AttributeError: 'Context' object has no attribute 'user_preferences'

Does anybody know why I get this error? Here is my code:

import bpy
from bpy.props import StringProperty

bl_info = {
'name': 'HELLO',
'category': 'All',
'author': 'user',
'version': (0, 0, 1),
'blender': (2, 80, 0),
'location': '3D_Viewport window -> N-Panel > Test',
'description': 'Test'
}

class writeFileOperator(bpy.types.Operator):
bl_idname = 'op.write'
bl_label = 'Write file'

def execute(self, context):
f = open(path + 'test_file.txt', "w")
return {"FINISHED"}

class writeFilePanel(bpy.types.Panel):
bl_idname = 'test.panel'
bl_label = 'TEST'
bl_space_type = 'VIEW_3D'
bl_region_type = 'UI'
bl_category = 'TEST'

def draw(self, context):
self.layout.operator("op.write", text="Write file")

bl_idname = __name__

name_folder = StringProperty(
name="Output folder",
subtype='DIR_PATH',
)

def draw(self, context):
layout = self.layout
layout.label(text="Where do you prefer to store your output files?")
layout.prop(self, "name_folder")

def register():
bpy.utils.register_class(writeFileOperator)
bpy.utils.register_class(writeFilePanel)
bpy.utils.register_class(saveLocFile)

def unregister():
bpy.utils.unregister_class(writeFileOperator)
bpy.utils.unregister_class(writeFilePanel)
bpy.utils.unregister_class(saveLocFile)

if __name__ == '__main__':
register()

• It's context.preferences there is no user_preferences (any more) ... The error is telling you this. Go to python console and type C.user_<TAB> (where C is bpy.context and <TAB> is the tab key to autocomplete) to confirm. – batFINGER Mar 16 at 13:53
• Thanks @batFINGER, it works perfectly! I also checked this through the Python console and, as you said, I can find bpy.context.preferences, but I cannot see bpy.context.user_preferences. – Alex Mekx Mar 16 at 14:03
• NP. Not sure when it changed, just edited same out of blender.stackexchange.com/a/70587/15543 – batFINGER Mar 16 at 14:06


text:
# Defining the inverse of arg-max function

Let us consider a function $f:[0,1]\rightarrow R^+$. Now if we consider a functional of $f$ as $$g=\mathop{\arg\max}_{x\in[0,1]}f(x).$$

Then I define inverse of $g$ is $g^{-1}(x)=\{\forall f :g=\mathop{\arg\max}_{x\in[0,1]}f(x) \}$. I am not sure if I am right or not. Any help will be highly appreciable.

• How are you defining the argmax function? In particular, does it return the set of all maximising x, or a particular such x? If you are choosing only one such x, how have you made it well defined? – James Jun 11 '15 at 14:20
• I think there is a typo in your question. You write: "Then the I am inverse". What do you mean by that? – Andrea Jun 11 '15 at 14:22
• Thanks @AndreaDiBiagio. I corrected it. – Janak Jun 11 '15 at 14:23
• @James. Thanks for your attention. Here I am defining the $argmax$ as the set of all maximizing $x$. – Janak Jun 11 '15 at 14:25
• NP, although I deleted it because Andrea is right. Maybe something more like $g^{-1}(y) = \{ f : y \in arg max f(x)\}$. The element of symbol to emphasize arg max is set valued. – muaddib Jun 11 '15 at 14:33

First off, let $F = \{f: [0,1] \to \mathbb{R}^+\}$. Then $g : F \to \mathcal{P}([0,1])$. That is $g$ maps from the set of all such functions $f$ to the powerset of the interval $[0,1]$. That should help you to understand the problem.
Then $g^{-1} : \mathcal{P}([0,1]) \to \mathcal{P}(F)$ given by $g^{-1}(\{x\}) = \{f \in F: g(f) = \{x\}\}$. Note that here I am using $\{x\}$ to denote an element of $\mathcal{P}([0,1])$.
Your function will return all $[0,1] \rightarrow \Bbb R^+$ which peak at a given real number between $0$ and $1$, if you managed to define it properly.
However you didn't define it properly. If you look at your expression for $g^{-1}(x)$ you'll see that $x$ appears as a dummy variable...


text:
# Call methods of C++ class in iPhone

This topic is 2670 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

Hi, I'm trying to use AngelScript in an iPhone game that we are doing but we are having some problems. I'm beeing able to call global functions in the script but I'm not being able to call methods of a C++ class. Can it be a restriction when running AS in iphone? I had some compiling problems before ( you can see the thread here http://www.gamedev.net/community/forums/topic.asp?topic_id=569572 ) and I'm thinking that maybe that can be related. I know that in this forum there are some users that could use AS in iphone... Did they have problems registering C++ methods in AS engine? I'll appreciate any help. I really want to use AS in my project. Thanks a lot!

##### Share on other sites
If it is specific to class methods, then it is possible that nobody tried that yet.

If anyone has any ideas or can confirm if registering class methods work properly on the iPhone I would very much appreciate if you could let us know.

I wish I could investigate this myself, but I do not have an iPhone, and you said in the other thread that it works on the simulator, so unfortunately I'll have to rely on the community to help with this.

##### Share on other sites
I needed the fix and I think I found it, at least it is working on my iPhone

I can confirm the problem is on Class Methods and they are threatened as if they were virtual ...

#ifndef AS_NO_CLASS_METHODS if( base == asCALL_THISCALL ) { internal->callConv = ICC_THISCALL; #ifdef GNU_STYLE_VIRTUAL_METHOD if( (size_t(ptr.ptr.f.func) & 1) ) internal->callConv = ICC_VIRTUAL_THISCALL; // Here it was wrongly setting as virtual #endif internal->baseOffset = ( int )MULTI_BASE_OFFSET(ptr); #if defined(AS_ARM) && defined(__GNUC__) // As the least significant bit in func is used to switch to THUMB mode // on ARM processors, the LSB in the __delta variable is used instead of // the one in __pfn on ARM processors. if( (size_t(internal->baseOffset) & 1) ) internal->callConv = ICC_VIRTUAL_THISCALL; #endif

[color="#77482d"][color="#000000"][font="arial, verdana, tahoma, sans-serif"]What I did to fix it was to go to as_config.h and added this line at line 533[/font]

 #undef GNU_STYLE_VIRTUAL_METHOD // added by Pogacha

[font="Menlo"][size=2]Just under this:
[/font]#elif (defined(_ARM_) || defined(__arm__)) // The IPhone use an ARM processor #define AS_ARM #define AS_IPHONE #define AS_ALIGN #define CDECL_RETURN_SIMPLE_IN_MEMORY #define STDCALL_RETURN_SIMPLE_IN_MEMORY #define THISCALL_RETURN_SIMPLE_IN_MEMORY #undef GNU_STYLE_VIRTUAL_METHOD // added by Pogacha [font="arial, verdana, tahoma, sans-serif"][color="#000000"][font="Menlo"]
[font="arial, verdana, tahoma, sans-serif"]And everything started working [/font][/font][/font]

A question that would help me:
Does native calling convention works on Android?

##### Share on other sites
Great!!!!

This has been a known bug for a long time now. Thank you very much for finding the solution. I'll have it checked in as soon as possible.

As far as I know native calling conventions are working on Android OS as well. At least when using the GNUC compiler and the phone is using the ARM processor.

Regards,

Andreas

##### Share on other sites
I've checked in the fix in revision 833.

Thanks!

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text:
# Why is $x(x+2)(x-3)$ not $x^2+2x(x-3)$?

How would you explain the principle why $x(x+2)(x-3)$ is not $x^2+2x(x-3)$ but $(x^2+2x)(x-3)$? This may involve the fundamentals of eliminating parenthesis.

• So people can better help you, do you understand why $x(x+2)=x^2+2x$? – Git Gud Nov 3 '14 at 16:49
• Sorry I should have included I just want to generalize this concept, instead of trying to attempt understand it explicitly. – Bright Nov 3 '14 at 16:53
• In that case Vladimir's answer below should be useful. – Git Gud Nov 3 '14 at 16:54
• Not a proof, but consider looking at what happens when $x$ is some specified number. For example, suppose $x=5.$ Then $x(x+2)(x-3)$ is the product of $5$ and $7$ and $2,$ which equals $70.$ However, $x^2 + 2x(x-3)$ is the sum of $5^2 = 25$ and $(2)(5)(2) = 20,$ which equals $45.$ Finally, $(x^2 + 2x)(x-3)$ is the product of $5^2 + (2)(5) = 25 + 10 = 35$ and $5-3 = 2,$ which equals $70.$ In particular, note that in the original version, it's $35$ that gets multiplied by $2,$ which the $(x^2+2x)(x-3)$ version maintains. – Dave L. Renfro Nov 3 '14 at 17:02

This is the distributive property for multiplication: $(a+b)(c+d)=a(c+d)+b(c+d)$. In your case:

$$k(a+b)(c+d)=(ka+kb)(c+d)=ka(c+d)+kb(c+d).$$

This comes from:

$$k(a+b) = \overbrace{(a+b)+(a+b)+\dotsc+(a+b)}^{k\text{-times}} = a+b+a+b+\dotsc+a+b=\overbrace{a+a+\dotsc+a}^{k\text{-times}}+\overbrace{b+b+\dotsc+b}^{k\text{-times}}=ka+kb.$$

Generalizing a bit more:

$$(k+p)(a+b) = \overbrace{(a+b)+(a+b)+\dotsc+(a+b)}^{(k+p)\text{-times}} = a+b+a+b+\dotsc+a+b=\overbrace{a+a+\dotsc+a}^{(k+p)\text{-times}}+\overbrace{b+b+\dotsc+b}^{(k+p)\text{-times}}=(k+p)a+(k+p)b.$$

• This is exactly the answer to my question. Many thanks. – Bright Nov 3 '14 at 16:57
• You're welcome. – Vladimir Vargas Nov 3 '14 at 16:59
• The explanation doesn't work when $k$ and $p$ are not natural numbers. The better explanation would be using rectangle areas, like this picture shows (except, of course, you can use real numbers for the areas instead). – user26486 Nov 3 '14 at 18:38
• Do you have a counter example? – Vladimir Vargas Nov 3 '14 at 18:43
• Use @mathh when replying so that I get a notification. And you can't add something $\pi$ times. But you can find the area of a rectangle with a side $\pi$. – user26486 Nov 9 '14 at 16:56

Here's my attempt to explain it in a very super simple way based on what you already know. Make sure you make yourself familiar with Vladimir's answer as well.

Consider...

$2*3*4=24$, or in other words, $6*4=24$ most of people understand it very well that the both are the same.

Now consider $3+3*4=15$ you know can't replace $2*3$, with $3+3$ in that equation. It breaks the equation if you do that.

Consider now $(3+3)*4=24$, hey this works.

Conclusion, the simplified multiplication of form $a+a+...+a$ within an equation has to be written within parenthesis. In order to preserve the consistency within the equation.

How would you explain the principle why $x(x+2)(x−3)$ is not $x^2+2x(x-3)$ but $(x^2+2x)(x-3)$? (it's about the lack of parenthesis)
$x(x+2)(x−3)=\overbrace{((x+2)+(x+2)+...+(x+2))}^{x\text{-times (notice parenthesis)}}(x−3)$
or the same can be noted, as Vladimir explained $k(a+b)(c+d)=(ka+kb)(c+d)$:
$(x^2+2x)(x-3)$


text:
zbMATH — the first resource for mathematics

Remark on a paper by R. L. Duncan concerning the uniform distribution mod 1 of the sequence of the logarithms of the Fibonacci numbers. (English) Zbl 0212.39502
Fibonacci Q. 7, No. 5, 465-466, 473 (1969).
Let $$(\mu_n)$$ be the sequence of Fibonacci numbers defined by $$\mu_1=1$$, $$\mu_2=2$$ and $$\mu_n=\mu_{n-1}+\mu_{n-2}$$ $$(n\geq 3$$. R. L. Duncan [Fibonacci Q. 5, 137–140 (1967; Zbl 0212.39501)] has shown that the sequence $$(\log \mu_n)$$ is uniformly distributed (mod 1), where the logarithm is taken to the base 10. In the paper under review the author gives a short proof of this result of Duncan, using the fact that if $$\xi=(1+\sqrt 5)/2$$ and if $$\omega\neq 0$$ is real and algebraic, then $$\xi^\omega$$ is not an algebraic number, and appealing to a theorem due to J. G. van der Corput [Acta Math. 56, 373–456 (1931; Zbl 0001.20102)]. As a result, the sequence $$(\log \mu_n)$$ is uniformly distributed (mod 1), provided that the base of the logarithm is chosen in such a way that $$\log\xi$$ is an irrational number. The author also proves that the sequence of integers $$[(\log \mu_n)]$$ is uniformly distributed in the sense of I. Niven [Trans. Am. Math. Soc. 98, 52–61 (1961; Zbl 0096.03102)].

MSC:
 11J71 Distribution modulo one 11K06 General theory of distribution modulo $$1$$ 11K31 Special sequences 11B39 Fibonacci and Lucas numbers and polynomials and generalizations
Full Text:


text:
# [luatex] babel, fontspec und lualatex

Khaled Hosny khaledhosny at eglug.org
Fri Jul 26 13:40:09 CEST 2013

On Fri, Jul 26, 2013 at 12:59:55PM +0200, Philipp Gesang wrote:
> ···<Datum: Friday, 26. July 2013>···<Von: Ulrike Fischer>···
>
> > Am Fri, 26 Jul 2013 12:19:23 +0200 schrieb Javier Bezos:
> >
> > > Ulrike,
> > >
> > >> The new babel redefines the \TeX command and surrounds it by
> > >> \textlatin and this reveals a bug:
> > >
> > > Do you know if it works with the old (3.8) babel? (I've not tried
> > > it out yet -- just back from holidays). I have not changed this part
> > > (afaik :-)) because I'm still investigating how to fix the whole
> > > \text<script> stuff in a backward compatible way.
> >
> > miktex still has Babel <v3.8m>, so I could test: There is the same
> > problem, the fontdimen is 0 and there is to much space between X and
> > n.
> >
> > Imho the correct solution would be that luatex/luaotfload sets
> > \fontdimen1 for italic fonts to a sensible positiv value.
>
> What’s “a sensible value” if italic correction is done on node
> level?

Note that \fontdimen1 is *not* italic correction, but the italic angle
of the font i.e. its slant amount.

> Someone knowledgeable about font parameters and how they translate to
> the original values would have to supply the code, though,

ConTeXt code in luaotfload already does that, at least I see that
copytotfm() sets parameters.slant for italic fonts, so someone needs to
check why this is not working as expected.

> especially when it comes to the more delicate parts described in
> appendix G.

You don’t need to worry about math font dimentions, the OpenType math
machinary does not need them (they might even confuse LuaTeX to thing it
is dealing with an old font) and old math fonts should have them in the

Regards,
Khaled
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# 深入一音频信号及其数字信号处理流程

In this post, I'll look at the benefits of using multiple perspectives when handling signals.

## A PRE-EXISTING AUDIO FILE

Let's say we have an audio file of interest. Let's load it into Audacity and zoom in a little (using View → Zoom → Zoom In, multiple times). The figure illustrates the audio signal: just a basic single-tone signal.

By continuing to zoom into the signal, we eventually get to the point of seeing individual samples as illustrated below. Notice that I've marked one of the samples in the figure. We'll look at this sample more detail later.

Looking at the signal in the neighborhood marked above we can now look at the three leftmost samples:

In the figure, we have three audio samples. Based on the vertical scale on the left, we can see that the leftmost sample seems to have has the value zero, right? The second and third samples have values greater than zero and less than 0.5 respectively.

Using a C++ application, I extract the first four values from the signal. So, the listing below illustrates the first four signal values as they are read in from the WAV file.

Value of signal data[0] 0.000031

Value of signal data[1] 0.136047

Value of signal data[2] 0.268311

Value of signal data[3] 0.392517

Notice in the listing, that the WAV data tells a slightly different story from Audacity. Namely, that the first sample is in fact not zero. It has the value 0.000031.

Again, this shows the merit of using different perspectives. One tool (i.e., Audacity) gives us one perspective, but another, in this case, handcrafted C++ tool gives us a more accurate view of the same data.

Let's take the experiment a little further and include some more data (7 points) in the excerpt as illustrated in the following figure.

What does the C++ program output for the data in this figure look like? The following listing provides the details.

Value of signal data[0] 0.000031

Value of signal data[1] 0.136047

Value of signal data[2] 0.268311

Value of signal data[3] 0.392517

Value of signal data[4] 0.505493

Value of signal data[5] 0.603577

Value of signal data[6] 0.684082

More signal values

Notice in this listing that the last value is around the 0.684 mark.

In practice, it may not be necessary to delve into such fine detail. But, it's important to note that, with the right tooling, it is feasible to do so. Using multiple tools also facilitates the cross-checking of your signal data.

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# Math Help - Product and Quotient Rule

1. ## Product and Quotient Rule

In B.C, the sales of specialized high-endurance, out dollar gear in millions of dollars is projected by

s(t)= 4t/t^2+2
0<t<10

where t is measured in years with t=0 corresponding to the beginning of 2000. How fast was the level of sales increasing at the beginning of 2005?

2. Originally Posted by lemontea
In B.C, the sales of specialized high-endurance, out dollar gear in millions of dollars is projected by

s(t)= 4t/t^2+2
0<t<10

where t is measured in years with t=0 corresponding to the beginning of 2000. How fast was the level of sales increasing at the beginning of 2005?
Do you mean : $s(t)=\frac{4t}{t^2+2}$?

3. Originally Posted by Chris L T521
Do you mean : $s(t)=\frac{4t}{t^2+2}$?

If this is the case, then find $s'(5)$

Using Quotient Rule:

$s'(t)=\frac{(t^2+2)(4)-(4t)(2t)}{(t^2+2)^2}\implies s'(t)=\frac{-4t^2+8}{(t^2+2)^2}$

Thus, $\color{red}\boxed{s'(5)=-\frac{92}{27^2}\approx -.1262}$

Using Product Rule:

$s(t)=(4t)(t^2+2)^{-1}$

$\therefore s'(t)=4(t^2+2)^{-1}-(4t)(t^2+2)^{-2}\cdot (2t)$
$\implies s'(t)=\frac{4}{t^2+2}-\frac{8t^2}{(t^2+2)^2}$
$\implies s'(t)=\frac{4t^2+8-8t^2}{(t^2+2)^2}=\frac{-4t^2+8}{(t^2+2)^2}$

Thus, $\color{red}\boxed{s'(5)=-\frac{92}{27^2}\approx -.1262}$


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# 1d channel

1. Sep 11, 2015

### aaaa202

I'm making some theoretical modelling for a system, which is effectively 1d in the sense that it is much longer the wide. This means (like in model for quantized conductance) that the energy bands are parabolas with a spacing equal to the energy difference between the ground state, first excited state, second excited state etc. (see attached figure).
Now an input parameter in my script is the number of electrons in the system and from that I wish to calculate the fermi level of the system. This is however giving me some trouble.
You can start from the assumption that only the first band is populated. Then calculate fermi level from that and if you find that this level is above where the second band starts I need to correct for this. But this becomes an infinite process, since the correction then needs to be corrected etc.
Therefore I ask you people out there. Is there any way, given the total number of electrons for the system, that I could find a closed form expression for the fermi level of the system?
Also the input parameter in my script is actually the electron density in the system rather than the total number of electrons. Is there a way to use this rather than the total number of electrons to calculate the fermi level?

#### Attached Files:

• ###### fermilevel.gif
File size:
4.4 KB
Views:
64
2. Sep 16, 2015


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1. ## Finding Formula for given sequence

I have the following sequence: 0 2 3 5 8 13 21 34..........
This is very close to the fibonacci sequence, but not exactly. Any ideas?

2. ## Re: Finding Formula for given sequence

Originally Posted by mikewienerm
I have the following sequence: 0 2 3 5 8 13 21 34..........
This is very close to the fibonacci sequence, but not exactly. Any ideas?
$F_0 = 0, F_1=2, F_3=3, F_n=F_{n-1}+F_{n-2}\quad\forall n\geq 3$

3. ## Re: Finding Formula for given sequence

This is a recursive formula. I was hoping someone could help me find a forumla where I can find F(n) without having to find the previous values. For example, finding F(50) would be very tedious.

4. ## Re: Fibonacci Sequence Formula

After the first term, this sequence is exactly the same as the Fibonacci sequence (with the first three terms truncated). Surely you can use the same formula to calculate terms $\geq 2$. I.e. if the fibonacci sequence is $F_1,F_2,...$ and your sequence here is $T_1,T_2,...$, set

$T_{n}=F_{n+2}=\frac{\varphi^{n+2}-\psi^{n+2}}{\sqrt5}$

for $n\geq 2$

5. ## Re: Fibonacci Sequence Formula

What Gusbob said, of course!

But also you can apply the same ideas that lead to the "usual" Fibonacci formula. If you "look for" a solution of the form $F_n= r^n$, the equation becomes $r^n= r^{n-1}+ r^{n-2}$. Dividing through by $r^{n-2}$ gives you $r^2= r- 1$ or $r^2- r+ 1= 0$. Solving that $r= \frac{1\pm\sqrt{5}}{2}$. That is, $F_n= A\left(\frac{1+\sqrt{6}}{2}\right)^n+ B\left(\frac{1- \sqrt{6}}{2}\right)^n$ for some constants A and B. That is exactly the solution you would get for the "usual" Fibonnacci formula. Putting $F_1= A\frac{1+ \sqrt{5}}{2}+ B\frac{1- \sqrt{6}}{2}= 0$ and $A\left(\frac{1+ \sqrt{5}}{2}\right)^2+ B\left(\frac{1- \sqrt{5}}{2}\right)^2= 2$ rather than setting them equal to the "usual" 1, 1, solve for A and b.

6. ## Re: Fibonacci Sequence Formula

Let G represent the Golden Ratio
Then Fn=(G^n+(G-1)^n))/Sqrt 5
Where ^ represents is to the power of
Another method is to use the Binomial Expansion by observing Pascal Triangle


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# Git keeps prompting me for password

I've been using Git for a while now, but the constant requests for a password are starting to drive me up the wall.

I'm using OSX and Github, and I set up Git and my SSH keys as instructed by GitHub's Set Up Git page . I've also added the github SSH key to my Mac OSX keychain, as mentioned on GitHub's SSH key passphrases page . My public key is registered with Git.

Nevertheless, every time I try to git pull, I have to enter my username and password. Is there something other than an SSH key that I need to set up for this?

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Silly question, but have you verified that the SSH key works when simply using ssh to the machine with git? –  Kurt Stutsman Oct 14 '11 at 20:27
You mean something like ssh -T git@github.com ? Yeah, that works just fine (if a little slow). –  Catherine Oct 14 '11 at 20:34
–  Cupcake Aug 22 '13 at 13:06
For https url, you can use (with git1.8.3+) a git credential helper 'netrc'. See a full example here. –  VonC Aug 22 '13 at 13:14

I think you may have the wrong git repo url. Make sure you're using the SSH one:

ssh://git@github.com/username/repo.git

And NOT the https or git one:

https://github.com/username/repo.git

You can now validate with just the SSH Key instead of the username and password.

[Edit:] If Git complains that 'origin' has already been added, open the .config file and edit the url = "..." part after [remote origin]

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This may be it. When I call git remote -v I get: origin github.com/Foo/Bar.git (fetch) origin github.com/Foo/Bar.git (push) whereas to work with SSH it seems that it should be: origin git@github.com:Foo/Bar.git (fetch) origin git@github.com:Foo/Bar.git (push) This may be because I originally checked out my project using GitHub's Mac application (mac.github.com). Any idea how I can fix it? –  Catherine Oct 14 '11 at 22:38
Either fix the url in the .git/config file, use git-remote to fix it, or delete your local repo and clone it again with the correct URL. –  static_rtti Oct 14 '11 at 22:49
Just to spell this out (as I needed it): open .git/config and in the [remote "origin"] section set url = ssh://git@github.com/username/Repo.git. That worked for me. –  Greg K Jul 1 '12 at 23:22
Odd, @GregK's solution didn't work for me, but url = git@github.com:organization/Repo.git did work. +1 for leading me down the right path though! Success! –  jmort253 Nov 19 '12 at 21:52
@GeneM. I'm pretty sure you can simply change the origin url of your clone in .git/gitrc to avoid re-cloning. –  static_rtti Aug 24 '13 at 19:20

Have you tried this in Terminal?

git config --global credential.helper osxkeychain

It enables git to use Keychain.app to store username and password and to retrieve the passphrase to your private ssh key from the keychain.

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This is by far the best way to do this since the Github application for OSX (maybe Windows as well) uses the https path for git repos by default. There is also a good reason for using https rather than ssh/git since many corporate networks only allow traffic on port 80 and 443 for security reasons. –  codehugger Sep 18 '12 at 2:11
You need git 1.7.10 or newer to use the credential helper. –  jbandi Dec 27 '12 at 23:34
+1 for keychain.app solution. This is GREAT for me because my employer's git server only supports http served via apache and they strongly discourage using the .netrc file method which puts your password in plaintext. –  Josh Mar 1 '13 at 21:12
Note, I got the error 'credential-osxkeychain' is not a git command. as I didn't have the credential helper installed. I followed the instructions here to install it: help.github.com/articles/set-up-git#password-caching –  Hugh Mar 11 '13 at 13:00
Yes you need to install git with the credential helper. Depending on how you install it (homebrew, macports, source, etc.) you might need to pass some compile flags. For macports, install it with port install git-core +credential_osxkeychain –  orkoden Mar 20 '13 at 17:12

Use this: Replace github.com with the appropriate hostname

git remote set-url origin git@github.com:user/repo.git

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Thanks. This was the simplest solution I found. –  Regnarg Aug 5 at 1:15

I figure you fixed your problem, but I don't see the solution here that helped me, so here it is.

Type in terminal:

echo "" > ~/.ssh/known_hosts

That will empty your known_hosts file, and you'll have to add every host you used and have connected to, but it solved the problem.

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cat /dev/null > ~/.ssh/known_hosts will do the same. –  the Tin Man Sep 28 '12 at 1:03
> ~/.ssh/known_hosts is even shorter :) –  Collin Allen Oct 17 '12 at 15:25
rm ~/.ssh/known_hosts should do the job too. I would advise against this though. –  orkoden Mar 20 '13 at 17:13
If you need to remove a host from ~/.ssh/known_hosts, there is a less impactful way than wiping out the file. ~/.ssh/known_hosts is just a text file and if you can find the offending hosts in the file, you can just delete their lines. You may want to back up the file before editing it. If you only have a few entries in the file, then wiping it out might not be a bad idea. I work on lots of servers so my ~/.ssh/known_hosts has hundreds of entries in it and I'm not quite ready to delete them all to remove a few entries. –  Tim Stewart 22 hours ago

Guide to git on windows and Github using SSH to push/pull http://nathanj.github.io/gitguide/tour.html

2. Set environment variable 'GIT_SSH' = 'path\to\plink.exe' (in installed putty folder) - VERY IMPORTANT!!!
3. RESTART WINDOWS EXPLORER for Env Variables to take effect (cannot only restart command prompt)
4. Run puttygen.exe to generate new key, copy the PUBLIC key to Github site
5. Save this new PRIVATE key somewhere safe on the disk (preferable not dropbox)
6. Run putty.exe and connect SSH to github.co
7. Quickly get to startup folder by running "shell:startup". 8 Make your private key startup with windows via pageant. Create a shortcut in Startup folder with syntax "path\to\pageant.exe" "path\to\privatekey"
8. We do not need to set the 'puttykeyfile' setting inside .git/config of our repos
9. VERY IMPORTANT is that the "SSH clone URL" of Github is used and not Https
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orkoden's answer on using the keychain with git in your terminal was incomplete and raises erros. This is what you have to do to save the username and password you enter in the the terminal in your keychain:

curl http://github-media-downloads.s3.amazonaws.com/osx/git-credential-osxkeychain -o git-credential-osxkeychain
sudo mv git-credential-osxkeychain /usr/local/bin
sudo chmod u+x /usr/local/bin/git-credential-osxkeychain

Then enter

git config --global credential.helper osxkeychain

If you have already did the part with git config before the curl stuff, it's no problem, it'll work

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I agree with "codehugger" and using the instruction of "orkoden" it worked for me - on netbeans 7.3 - when you rightclick on the file and select context menu - push - a 'push to remote' window opened - there are 2 options here

as you can see that the difference is the origin param in the url - you do not want to choose this option (1) you want to check option (2) and that works just fine for me. i hope this help someone.

Dung Le.

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