15398191
Precise static type analysis for object oriented programs
A precise static type analysis is important to make available dynamic aspects of object-oriented programs (OOPs) approximately known at compile-time. Many techniques have been proposed for static type analysis depending upon the tradeoff of cost and precision; the techniques may generate spurious possible types for a particular dynamic dispatch which makes the static type analysis imprecise. In this paper, we propose a symbolic execution based type analysis technique that analyzes the dynamic type inter-procedurally by keeping the flow of the program in consideration. We analyze test cases with different class hierarchies. The proposed technique was capable to resolve the target method for most of the dynamic dispatches at reduced computational cost.
537233
Evolutionary Multimodal Optimization Revisited
We revisit a class of multimodal function optimizations using evolutionary algorithms reformulated into a multiobjective framework where previous implementations have needed niching/sharing to ensure diversity. In this paper, we use a steady-state multiobjective algorithm which preserves diversity without niching to produce diverse sampling of the Pareto-front with significantly lower computational effort.
24684227
Adaptive Control of Anytime Algorithm Parameters
39741624
An Efficient Technique for Dynamic Slicing of Concurrent Java Programs
Program slice has many applications such as program debugging, testing, maintenance and complexity measurement. We propose a new dynamic program slicing technique for concurrent Java programs that is more efficient than the related algorithms. We introduce the notion of Concurrent Program Dependence Graph (CPDG). Our algorithm uses CPDG as the intermediate representation and is based on marking and unmarking the edges in the CPDG as and when the dependencies arise and cease during run-time. Our approach eliminates the use of trace files and is more efficient than the existing algorithms.
6342150
Frame based fair multiprocessor scheduler: a fast fair algorithm for real-time embedded systems
This paper presents frame based fair multiprocessor scheduler (FBFMS) which provides accurate real-time proportional fair scheduling for a set of dynamic tasks on a symmetric multiprocessor environment with O(1) scheduling overhead. FBFMS meets these seemingly contradictory goals by applying the benefits of virtual time round-robin scheduling mechanism along with a frame based scheduling approach. Simulation results show that the algorithm provides 2.5 to 26 times speedup (over O(lg n) complexity schedulers) with distortion in fairness less than 1% in most cases, and less than 15% in the worst case.
5790802
Object-oriented symbol management in syntax-directed compiler systems
Each symbol in a source program has a series of attributes that govern the operations performed on it. In this paper, we explore object-oriented techniques for representing the attributes of symbols and translating the operations performed on them. This approach is shown superior in memory and run-time speed to the procedural style traditionally used for writing compilers. We demonstrate object-oriented symbol management in a compiler for an arithmetic subset of C. We have used C++ --- a single-dispatching language --- to implement the same, but we emphasize the need for multiple dispatching to develop programs in a heavily-object-oriented style.
6842097
Automated control synthesis for an assembly line using discrete event system control theory
The design of logic controllers for event-driven systems continue to rely largely on intuitive methods rather than on formal techniques. This approach results in a control code that requires extensive verification, is hard to maintain and modify, and may even fail at times. Supervisory control theory (SCT) provides a formal approach to logic control synthesis. In order to demonstrate the usefulness of the supervisory control theory in manufacturing systems, an educational test-bed that simulates an automated car assembly line has been built using LEGO/spl reg/ blocks. Finite state machines (FSMs) are used for modeling operations of the assembly line, and for the specifications that accomplish the task of successfully completing the assembly repeatedly. Using the technique of SCT, we derive a supervisor that enforces the specifications while offering the maximum flexibility of assembly. Subsequently a controller is extracted from the maximally permissive supervisor for the purpose of implementing the control by selecting, when possible, at most one controllable event from among the ones allowed by the supervisor. Testing to check the correctness of the control code is reduced, since the controller is guaranteed to enforce the specifications.
15931484
Optimal slope bin classification in gradient adjusted predictor for lossless compression of medical images
Gradient adjusted predictor (GAP) uses seven fixed range of slope quantization bins and different predictors associated with each bin, for prediction of pixels of all kinds of images. Criteria for range of slope in the bins and associated predictors are not reported in the literature. This paper presents a technique for slope quantization bins which are optimum for a given set of images. It also presents a technique for finding a statistically optimal predictor for a given range of slope bin. Simulation results, for medical images, using optimal slope bins and associated predictors show a significant better compression performance as compared to the other methods such as GAP and edge-directed prediction (EDP) method. The proposed method and GAP has same order of computational complexity while EDP is computationally much expensive.
7841699
Dynamic data fusion for future sensor networks
DFuse is an architectural framework for dynamic application-specified data fusion in sensor networks. It bridges an important abstraction gap for developing advanced fusion applications that takes into account the dynamic nature of applications and sensor networks. Elements of the DFuse architecture include a fusion API, a distributed role assignment algorithm that dynamically adapts the placement of the application task graph on the network, and an abstraction migration facility that aids such dynamic role assignment. Experimental evaluations show that the API has low overhead, and simulation results show that the role assignment algorithm significantly increases the network lifetime over static placement.
15001801
Managing Flexibility in Distributed Information Systems Architectures
Competitive pressures are forcing organizations to be agile and flexible. Response to changing environmental conditions is an important factor in determining corporate performance. Organizational flexibility is in turn closely related to the management of information systems. Rexibility of information systems needs to be actively managed. Information systems in organizations have evolved from being a function of a centralized MIS department to a function dependent on a distributed collection of information systems resources (hardware, software, and people). This distributed collection of resources has been referred to as the Distributed Information Systems Architecture. Managing flexibility in distributed information systems architectures is an interesting and challenging problem. The inlportance offlexibilityboth at the organizational and information systems levels has been recognized by research in management (Bahrami 1992), operations management (Sethi 1990), and MIS (Lacity, Willcocks anditeny 1995). However, flexibility in distributed information system architectures has not been examined in detail. Flexibility in distributed information system architectures can be of several types. Each type of flexibility has distinct characteristics. Understanding different types of flexibility in the context of distributed information system architectures is therefore extremely important. 'Ihe operations management literature on flexibility is used as a starting point to categorize various types of flexibility. Analysis of secondarydata using grounded theory (Strauss and Corbin 1990) is employed to identifyseveral different types of flexibility. Secondary data used consists of articles on outsourcing and management of information systems from academic publications as well as from practitioner publications such as Datamation, /4/Onnation Week etc. A taxonomy for understanding flexibility in distributed information system architectures is developed. The relationship between various t>pes of flexibilityand different information s>Stems functions is explored. This taxonomy of flexibility, as well as the relationship between types of flexibility, information system functions, and resource requirements has important implications for evaluation of outsourcing decisions. REFERENCES Bahrami, H. 'The Emerging Flexible Organization: Perspectives from Silicon Valley." Cal{/brnia Management Review, Summer 1992, pp. 34-51. Lacity, M. C.; Willcocks, L. P.; and Feeny, D. F. "IT Outsourcing: Maximize flexibility and Control." Harvard Business Review, May-June 1995, pp. 83-93. Sethi, S. K, and Sethi, S. P. "Flexibility in Manufacturing: A Survey." Inteniational Journal ofFlexibleManufacturing Systems, Volume 2,1990, pp. 289-328. Strauss, A, and Corbin, J. Basics ofQuaUtative Research: Grounded 77:eory, Procedures and Techniques. NewburyPark, California: Sage Publications, 1990.
8733679
Stochastic Fluid Theory for P2P Streaming Systems
We develop a simple stochastic fluid model that seeks to expose the fundamental characteristics and limitations of P2P streaming systems. This model accounts for many of the essential features of a P2P streaming system, including the peers' realtime demand for content, peer churn (peers joining and leaving), peers with heterogeneous upload capacity, limited infrastructure capacity, and peer buffering and playback delay. The model is tractable, providing closed-form expressions which can be used to shed insight on the fundamental behavior of P2P streaming systems. The model shows that performance is largely determined by a critical value. When the system is of moderate-to-large size, if a certain ratio of traffic loads exceeds the critical value, the system performs well; otherwise, the system performs poorly. Furthermore, large systems have better performance than small systems since they are more resilient to bandwidth fluctuations caused by peer churn. Finally, buffering can dramatically improve performance in the critical region, for both small and large systems. In particular, buffering can bring more improvement than can additional infrastructure bandwidth.