7866306
Two-level assurance of QoS requirements for distributed real-time and embedded systems
Assuring quality of service (QoS) requirements is critical when assembling a distributed real-time and embedded (DRE) system from a repository of existing software and hardware components. This paper presents a two-level approach for assuring satisfaction of QoS requirements in the context of a reduced design space for DRE systems. Techniques from artificial intelligence and statistics are used to fulfill these collective objectives at system assembly time. The result not only lessens the overhead of validation of QoS requirements at run-time, but also reduces the development and integration cost of DRE systems.
7160160
QoS-UniFrame: a Petri net-based modeling approach to assure QoS requirements of distributed real-time and embedded systems
Assuring quality of service (QoS) requirements is critical when assembling a distributed real-time and embedded (DRE) system from a repository of existing components. This paper presents a two-level approach for assuring satisfaction of QoS requirements in the context of a reduced design space for DRE systems. A dynamic and parallel approach is introduced to prune off the infeasible design spaces at the first level. Evolutionary algorithms cooperating with a domain-specific scripting language then discard less probable design spaces using statistics. These techniques fulfill the collective objectives of pruning and assuring the design space at system assembly time.
18135743
A clustering entropy-driven approach for exploring and exploiting noisy functions
Linear, Gaussian, fitness proportional, clustering, and Rosca entropies are succinct measures of diversity that have been applied to balance exploration and exploitation in evolutionary algorithms. In previous studies, an entropy-driven approach using linear entropy explicitly balances and/or searches optimal solutions for the selected unimodal and multimodal functions excluding noisy functions. This paper investigates the reasons for such an exception and introduces a clustering entropy-driven approach to solve the problem. Such an approach provides a coarse-grained diversity measure that filters the noise of functions, varies cluster size and categorizes individuals at the genotype level. The experimental results show that the clustering entropy-driven approach further improves the searching results of noisy functions by one more degree.
3186847
A Hardware/Software Framework for Real-Time Spiking Systems
One focus of recent research in the field of biologically plausible neural networks is the investigation of higher-level functions such as learning, development and modulatory functions in spiking neural networks. It is desirable to explore these functions in physical neural network systems operating in real-time. We present a framework which supports such research by combining hardware spiking neurons implemented in analog VLSI (aVLSI) together with software agents. These agents are embedded in the spiking communication of the network and can change the parameters and connectivity of the network. This new approach incorporating feedback from active software agents to aVLSI hardware allows the exploration of a large variety of dynamic real-time spiking network models by adding the flexibility of software to the real-time performance of hardware.
13865796
Virtual Screening of Novel Noncovalent Inhibitors for SARS-CoV 3C-like Proteinase
The SARS coronavirus 3C-like proteinase is considered as a potential drug design target for the treatment of severe acute respiratory syndrome (SARS). Owing to the lack of available drugs for the treatment of SARS, the discovery of inhibitors for SARS coronavirus 3C-like proteinase that can potentially be optimized as drugs appears to be highly desirable. We have built a "flexible" three-dimensional model for SARS 3C-like proteinase by homology modeling and multicanonical molecular dynamics method and used the model for virtual screening of chemical databases. After Dock procedures, strategies including pharmocophore model, consensus scoring, and "drug-like" filters were applied in order to accelerate the process and improve the success rate of virtual docking screening hit lists. Forty compounds were purchased and tested by HPLC and colorimetric assay against SARS 3C-like proteinase. Three of them including calmidazolium, a well-known antagonist of calmodulin, were found to inhibit the enzyme with an apparent K(i) from 61 to 178 microM. These active compounds and their binding modes provide useful information for understanding the binding sites and for further selective drug design against SARS and other coronavirus.
14314870
Formalization, Testing and Execution of a Use Case Diagram
Errors in a requirements model have prolonged detrimental effects on reliability, cost, and safety of a software system. It is very costly to fix these errors in later phases of software development if they cannot be corrected during requirements analysis and design. A use case diagram, as a requirements model, plays an important role in giving requirements for a software system. It provides a communication tool between software requirements developers and prospective users to understand what requirements of a software system are. However most descriptions of a use case diagram are written in some informal language, leading to possible misunderstanding between developers and users. In this paper, we propose a new rigorous review technique which can be applied to software requirements models. Using this new technique before a software system is fully designed will help us find some potential errors in a requirements model, resulting in reduced time, labor and expenditure in software development.
8071150
TCP-Illinois: A loss- and delay-based congestion control algorithm for high-speed networks
We introduce a new congestion control algorithm for high-speed networks, called TCP-Illinois. TCP-Illinois uses packet loss information to determine whether the window size should be increased or decreased, and uses queueing delay information to determine the amount of increment or decrement. TCP-Illinois achieves high throughput, allocates the network resource fairly, and is incentive compatible with standard TCP. We also build a new stochastic matrix model, capturing standard TCP and TCP-Illinois as special cases, and use this model to analyze their fairness properties for both synchronized and unsynchronized backoff behaviors. We finally perform simulations to demonstrate the performance of TCP-Illinois.
1976770
Self-independent Petri Nets for Distributed Systems
We propose that asynchronous mechanism for communication should be considered as a primitive for semantic models of distributed systems in contrast to the synchronous mechanism (hand-shaking) of CSP (Hoare, 1985) and of CCS (Milner, 1989). By doing so, we present an approach to producing a deadlock-free system, and give a denotational model for CCS in a non-interleaving fashion.