15213655
The design and implementation of intelligent transportation Web services
The paper presents the design and implementation of an intelligent transportation Web service (ITWS) and studies various QoS requirements for the Web service infrastructure. In particular, we pay attention to the performance issues on ITWS data transmission and compression. Since SOAP message is a textual document, we can improve the data transmission time by compressing data on transmission. In our experiment, compressing data before or after SOAP serialization both can reduce the size of transmitted message down to as little as 2% and cut the response time to a quarter of the original message.
15828117
Enhancing external consistency in real-time transactions
Real-time computing brings two new requirements to database management. The first is the deadline constraint which requires better scheduling algorithms to meet transaction deadfines. The second requirement is the temporal validity, or external consistency[Lin89], requirement of data: a real-time database must prevent data from being corrupted not only by the executions of concurrent transactions but also by the delay from sharing computing resources and real-time scheduler decisions. In this paper, we study the external consistency requirement in real-time databases. We propose a semantic-based concurrency control scheme that prefers the external consistency to the traditional serializability. Two new concepts are introduced in our work. An update of a physical object value is considered to be compatible to those read operations that need to access the most recent data. Secondly, if a transaction depends strongly on the validity of the value of an object, a new update may cause the transaction to be aborted since continuing the transaction may be harmful to the appfication. A real-Life example is the stock market database. A trading program may be executed for a long time and its read operations should not block any new updates. Moreover, if there is a big sudden change in a particular stock price, it may be better to abort an on-going transaction rather than letting it make some invalid decisions.
22001959
A Pinwheel Scheduler for Three Distinct Numbers with a Tight Schedulability Bound
Abstract. Given a multiset of positive integers 
 $A=\{a_1,a_2,\ldots,a_n\}$ , the pinwheel problem is to find an infinite sequence over 
 $\{1,2,\ldots,n\}$ such that there is at least one symbol i within any subsequence of length ai. The density of A is defined as 
 $\rho(A)=\sum^n_{i=1} (1/a_i)$ . In this paper we limit ourselves to instances composed of three distinct integers. The best scheduler [5] published previously can schedule all instances with a density of less than 0.77. A new and fast scheduling scheme based on spectrum partitioning is presented in this paper which improves the 0.77 result to a new 
 $\frac{5}{6}\approx 0.83$ density threshold. This scheduler has achieved the tight schedulability bound of this problem.
15072976
The design and implementation of real-time schedulers in RED-linux
Researchers in the real-time system community have designed and studied many advanced scheduling algorithms. However, most of these algorithms have not been implemented since it is very difficult to support new scheduling algorithms on most operating systems. To address this problem, we enhance the scheduling mechanism in Linux to provide a flexible scheduling framework. In the real-time and embedded Linux (RED-Linux) project, we implement a general scheduling framework which divides the system scheduler into two components: dispatcher and allocator. The dispatcher provides the mechanism of system scheduling and resides in the kernel space. The allocator is used to define the scheduling policy and implemented as a user space function. This framework allows users to implement application-specific schedulers in the user space which is easy to program and to debug. The framework also relieves the deficiency from the stock Linux scheduler which is not designed for real-time applications. To further enhance its power, a hierarchical scheduling mechanism has been provided in RED-Linux to allow a system designer to integrate different real-time applications together. Using scheduling groups, real-time jobs can be managed and scheduled in a hierarchical manner. In this paper, we discuss how the group mechanism is implemented in RED-Linux.
13997680
Distributed real-time system design using CBS-based end-to-end scheduling
Distributed real-time applications share a group of processors connected by some local area network. A rigorous and sound methodology to design real-time systems from independently designed distributed real-time applications is needed. In this paper, we study a distributed real-time system design scheme using CBS-based end-to-end scheduling. The scheduling scheme utilizes CBS to allocate both CPU shares and network bandwidth to a distributed real-time application when it arrives at the system. Our proposed solution uses the same scheduling paradigm for both resources. In this way, we believe the system can have a more consistent scheduling objective and may achieve a tighter schedulability condition.
27737931
Designing multimedia applications on real-time systems with SMP architecture
Large real-time multimedia systems such as flight simulators have adopted multiprocessor architecture to handle the large amount of events and computations. Existing realtime scheduling algorithms designed for single-processor systems such as Rate Monotonic (RM) and Earliest Deadline First Algorithm (EDF) have very poor performance on multiprocessor systems. On the other hand, most online scheduling algorithms for multiprocessor systems have poor schedulability conditions for real-time applications. In this paper, we study different ways to design real-time applications on SMP machines.
16978334
Evaluating a class of distance-mapping algorithms for data mining and clustering
A distance-mapping algorithm takes a set of objects and a distance metric and then maps those objects to a Euclidean or pseudoEuclidean space in such a way that the distances among objects are approximately preserved. Distance mapping algorithms are a useful tool for clustering and visualization in data intensive applications, because they replace expensive distance calculations by sum-of-square calculations. This can make clustering in large databases with expensive distance metrics practical. In this paper we present five distance-mapping algorithms and conduct experiments to compare their performance in data clustering applications. These include two algorithms called FastMap and MetricMap, and three hybrid heuristics that combine the two algorithms in different ways. Experimental results on both synthetic and RNA data show the superiority of the hybrid algorithms. The results imply that FastMap and MetricMap capture complementary information about distance metrics and therefore can be used together to great benefit. The net effect is that multi-day computations may be done in minutes.
17442336
Ordinal association rules for error identification in data sets
A new extension of the Boolean association rules, ordinal association rules, that incorporates ordinal relationships among data items, is introduced. One use for ordinal rules is to identify possible errors in data. A method that finds these rules and identifies potential errors in data is proposed.
13196530
Amino Acid Substitution Matrices from an Artificial Neural Network Model
An amino acid substitution matrix specifies probabilities of substitutions for each pair of the 20 amino acids. Log-odds scores transformed from the values in substitution matrices are widely used to construct protein sequence alignments. Any given substitution matrix is suited to matching sequences diverged by a specific evolutionary distance. However, for a given set of sequences, it is not always clear what matrix should be used. We used an artificial neural network model to predict probabilities of amino acid substitutions with alignment samples of different evolutionary distances. From this internal description, substitution matrices suitable for detecting relationships at any chosen evolutionary distance can be instantly generated. By using the additional information of evolutionary distances, the average cross entropy error of our neural network model is lower than that of a series of BLOSUM and PET matrices over all testing sets. Our model is more accurate on the prediction of amino acid substitution probabilities.
5879747
Automatic information discovery from the "invisible Web"
A large amount of online information resides on the "invisible Web" - Web pages that are generated dynamically from databases and other data sources hidden from the user. They are not indexed by a static URL but are generated when queries are made via a search interface (a specialized search engine). In this paper, we propose a system that is capable of automatically making use of these specialized engines to find information on the invisible Web. We describe our overall architecture and process: from obtaining the search engines to picking the right engines to query. Experiments show that we can find information that is not found by traditional search engines.
22041790
Magic cubes and hypercubes of order 3
Abstract A general method to construct third-order magic cubes and hypercubes is described. It is shown that magic hypercubes of order 3 must be symmetrical and there are exactly 58 such hypercubes in 4-dimensional space, not counting rotations and reflections.