2647804
Extended DBP for (m, k)-Firm Based QoS
In this paper, an extended DBP (E_DBP) scheme is studied for (m,k)-firm constraint. The basic idea of the proposed algorithm takes into account the distance to exit a failure state, which is a symmetrical notion of distance to fall into a failure state in DBP. Quality of Service (QoS) in terms of dynamic failure and delay is evaluated. Simulation results reveal the effectiveness of E_DBP to provide better QoS.
7144496
Loss-tolerant QoS using firm constraints in guaranteed rate networks
We propose a trade-off between hard and soft real-time guarantees to maintain an acceptable QoS guarantee in overload condition and maximize efficiently the utilization of network resources. The key of our solution is that many real-time applications are loss-tolerant, but the loss profile must be well defined since successive packet losses are not suitable. We use the concept of (m,k)-firm timing constraints to define a novel guaranteed loss-tolerant QoS. Therefore, we extend the basic WFQ algorithm to take into account the firm timing constraints to provide lower delay guarantees without violating bandwidth fairness or misusing network resources. The proposal is called (m,k)-WFQ. Using network calculus formalism, analytic study gives the deterministic delay bound provided by the (m,k)-WFQ algorithm for upper bounded arrival curve traffic. Theoretical results and simulations show a noticeable improvement on delay guarantee made by (m,k)-WFQ compared to standard WFQ algorithm without much degrading bandwidth fairness.
11425513
Graceful degradation of loss-tolerant QoS using (m, k)-firm constraints in guaranteed rate networks
The Weighted Fair Queueing (WFQ) scheduling algorithm and its variants can be used to provide real-time guarantees by making bandwidth reservation. However, while hard guarantees are based on a peak workload model that leads to underutilize network resources, soft guarantees, based on average workload model, are not always sufficient to maintain acceptable Quality-of-Service (QoS) since consecutive packet losses or deadline misses may occur, which are not suitable for real-time applications. In this paper, we propose a trade-off between hard and soft real-time guarantees to maintain an acceptable QoS in overload conditions and efficiently maximize the utilization of network resources. The key to our solution is based on the fact that many real-time applications, such as voice and video, are loss-tolerant. The loss profile must be well defined, and such a profile can be easily specified using the (m,k)-firm model. Therefore, we propose the (m,k)-WFQ algorithm to take into account (m,k)-firm timing constraints to provide delay guarantees of at least m packets out of any k consecutive packets without violating bandwidth fairness or misusing network resources. Using the Network Calculus theory, an analytic study gives the deterministic delay bound provided by the (m,k)-WFQ algorithm for upper bounded arrival curve traffic. We extend our analytic results for guaranteed-rate networks, such as the IntServ QoS model and ATM networks, and the DiffServ QoS model. Analytic results and simulations show a noticeable improvement in delay guarantee made by (m,k)-WFQ compared to WFQ without much degradation of bandwidth fairness.
9240638
An Irregular Search Window Reuse Scheme for Motion Estimation in MPEG-2 to H.264 Transcoding
Motion estimation (ME) is a computation-intensive operation in video coding system. In MPEG-2 to H.264 transcoding, motion vector (MV) from MPEG-2 reused as search center in H.264 encoder is a simple but effective technique to simplify ME procedure. However directly introducing MPEG-2 MV will bring irregular overlapping between search windows of successive macroblocks (MB) which invalidates the data reuse scheme in hardware design of ME module. In this paper, the authors propose a search window reuse scheme for transcoding in HDTV application. By utilizing the similarity between neighboring MVs, overlapping of search windows between successive MBs can be regularized. Experiment results show that our method achieve average 93.1% search window reuse rate in HDTV sequence with almost no video quality degradation. And the bandwidth can be reduced to 92.5 Mbytes/s based on theoretical calculation which is only 40.6% of that without this scheme.
25329703
Monocular Perception of Biological Motion in Johansson Displays
Computer perception of biological motion is key to developing convenient and powerful human?computer interfaces. Algorithms have been developed for tracking the body; however, initialization is done by hand. We propose a method for detecting a moving human body and for labeling its parts automatically in scenes that include extraneous motions and occlusion. We assume a Johansson display, i.e., that a number of moving features, some representing the unoccluded body joints and some belonging to the background, are supplied in the scene. Our method is based on maximizing the joint probability density function (PDF) of the position and velocity of the body parts. The PDF is estimated from training data. Dynamic programming is used for calculating efficiently the best global labeling on an approximation of the PDF. Detection is performed by hypothesis testing on the best labeling found. The computational cost is on the order of N4 where N is the number of features detected. We explore the performance of our method with experiments carried on a variety of periodic and nonperiodic body motions viewed monocularly for a total of approximately 30,000 frames. The algorithm is demonstrated to be accurate and efficient.
16612931
Efficient computation of close lower and upper bounds on the minimum number of recombinations in biological sequence evolution
MOTIVATION
We are interested in studying the evolution of DNA single nucleotide polymorphism sequences which have undergone (meiotic) recombination. For a given set of sequences, computing the minimum number of recombinations needed to explain the sequences (with one mutation per site) is a standard question of interest, but it has been shown to be NP-hard, and previous algorithms that compute it exactly work either only on very small datasets or on problems with special structure.


RESULTS
In this paper, we present efficient, practical methods for computing both upper and lower bounds on the minimum number of needed recombinations, and for constructing evolutionary histories that explain the input sequences. We study in detail the efficiency and accuracy of these algorithms on both simulated and real data sets. The algorithms produce very close upper and lower bounds, which match exactly in a surprisingly wide range of data. Thus, with the use of new, very effective lower bounding methods and an efficient algorithm for computing upper bounds, this approach allows the efficient, exact computation of the minimum number of needed recombinations, with high frequency in a large range of data. When upper and lower bounds match, evolutionary histories found by our algorithm correspond to the most parsimonious histories.


AVAILABILITY
HapBound and SHRUB, programs implementing the new algorithms discussed in this paper, are available at http://wwwcsif.cs.ucdavis.edu/~gusfield/lu.html
16347620
Towards detection of human motion
Detecting humans in images is a useful application of computer vision. Loose and textured clothing, occlusion and scene clutter make it a difficult problem because bottom-up segmentation and grouping do not always work. We address the problem of detecting humans from their motion pattern in monocular image sequences; extraneous motions and occlusion may be present. We assume that we may not rely on segmentation or grouping and that the vision front-end is limited to observing the motion of key points and textured patches in between pairs of frames. We do not assume that we are able to track features for more than two frames. Our method is based on learning an approximate probabilistic model of the joint position and velocity of different body features. Detection is performed by hypothesis testing on the maximum a posteriori estimate of the pose and motion of the body. Our experiments on a dozen of walking sequences indicate that our algorithm is accurate and efficient.
7172331
Enhanced Strict Multilevel Successive Elimination Algorithm for Fast Motion Estimation
This paper presents an enhanced strict multilevel successive elimination algorithm (EMSEA) for fast block-matching motion estimation, which is based on the previous strict multilevel successive elimination algorithm (SMSEA) (Song et al., 2006). Different to the SMSEA algorithm with fixed parameters, in EMSEA algorithm, the whole search area is divided into two regions and each region has its own parameters. Therefore, the computation complexity of SMSEA algorithm can be further decreased. Experiments show that the proposed EMSEA algorithm can reduce 16.2% of the SMSEA computation and maintain almost the same image quality, which is better than the TSS and DS algorithms.