Application-independent Manner Research Articles

Small Constant Mean-Error Imprecise Adder/Multiplier for Efficient VLSI Implementation of MAC-Based Applications

Due to considerable effectiveness of the imprecise computing paradigm in hardware implementation of many applications, great attention has been recently paid by many research groups to develop different novel imprecise computational blocks such as adders and multipliers. Traditionally, the imprecise blocks are developed in an application independent manner, just similar to development of a conventional precise block. This article investigates the systematic application oriented development of the imprecise computational blocks which results in more customized components. The main focus is on the development of customized imprecise adder/multiplier for efficient implementation of a general multiply-accumulate (MAC) block as the basic building block of many imprecision tolerant applications including digital signal processing and soft computing. To develop some customized blocks for the MAC, the error behaviors of the suitable imprecise adder and multiplier are first extracted by analyzing the MAC. Based on analysis results, efficient small constant mean-error imprecise adder and multiplier are developed based on a systematic mathematical-logical approach. A wide range of synthesis and simulation results are provided to demonstrate efficiency of custom developed imprecise blocks with respect to some of the best existing imprecise blocks in a general MAC and a real 2D-Convolution application.

Hardware-Assisted Run-Time Monitoring for Secure Program Execution on Embedded Processors

Embedded system security is often compromised when "trusted" software is subverted to result in unintended behavior, such as leakage of sensitive data or execution of malicious code. Several countermeasures have been proposed in the literature to counteract these intrusions. A common underlying theme in most of them is to define security policies at the system level in an application-independent manner and check for security violations either statically or at run time. In this paper, we present a methodology that addresses this issue from a different perspective. It defines correct execution as synonymous with the way the program was intended to run and employs a dedicated hardware monitor to detect and prevent unintended program behavior. Specifically, we extract properties of an embedded program through static program analysis and use them as the bases for enforcing permissible program behavior at run time. The processor architecture is augmented with a hardware monitor that observes the program's dynamic execution trace, checks whether it falls within the allowed program behavior, and flags any deviations from expected behavior to trigger appropriate response mechanisms. We present properties that capture permissible program behavior at different levels of granularity, namely inter-procedural control flow, intra-procedural control flow, and instruction-stream integrity. We outline a systematic methodology to design application-specific hardware monitors for any given embedded program. Hardware implementations using a commercial design flow, and cycle-accurate performance simulations indicate that the proposed technique can thwart several common software and physical attacks, facilitating secure program execution with minimal overheads

On the design of emergent systems: an investigation of integration and interoperability issues

Many useful manmade systems in this world are extremely complex; a typical example is a large infrastructure. No design team ever invents these artifacts because they are too complex. These artifacts are made by combining existing elements (legacy) and by building new subsystems without explicit and comprehensive up-front coordination. To a large extent, these complex systems emerge and evolve. Experience shows that designers frequently fail to develop artifacts that, when combined, facilitate the emergence of effective and efficient systems. This paper formally elaborates the mechanism behind this phenomenon, and proposes principles for the design of components for emergent systems. The above insights were gained during the development of research prototypes for multi-agent manufacturing control; manufacturing systems are notorious for experiencing integration and interoperability problems as described above. Consequently, the design principles are discussed and illustrated on the design of multi-agent manufacturing control systems but also on work by others. Finally, although this paper mainly discusses the above in a generic fashion, and although the generic statements hold in an application-independent manner, it is important to appreciate that the applicability of the above insights and principles has significant limitations, which are discussed in the paper.

JDBC demonstration courseware using Servlets and Java Server Pages

This paper describes the design and functionality of courseware developed to demonstrate the JDBC API. The courseware is used in an advanced undergraduate database course that emphasizes the use of Web access to database systems. The JDBC courseware is written using Java Servlets and Java Server Pages, allowing the user to view the metadata associated with a database, to view and browse the information in a database according to the database metadata, and to query and/or manipulate data using SQL statements. The advantage of the courseware is that it demonstrates the main functionality of the JDBC API in an application-independent manner. The courseware can access any ODBC-compliant database, emphasizing the generality of the JDBC API and helping students understand how JDBC can be used to query the metadata of the database as well as the database contents.

Impact: a platform for collaborating agents

The paper discusses the Impact platform (Interactive Maryland Platform) for collaborative agents. Impact agents consist of software code with an associated wrapper that agentizes the code. A set of specialized servers facilitate agent interoperability in an application-independent manner.

Applicability of SIGNAL in safety critical system development

This paper concerns the specification of functional and safety requirements of a safety critical system independently, and subsequent validation of the integrated requirements in the synchronous data-flow formalism SIGNAL. The SIGNAL language provides a unified framework for hierarchical development of systems by refinement of specifications. Validation of specifications can be realised through a formal calculus based on the semantics of the language or through functional simulation. In this context, the research reported attempts safety management in critical real-time systems in an application–independent manner. This is based on the possibility of identifying low and high risk states in a system and expressing its functional behaviour as transitions between pairs of states of different levels of risk. Safety requirements become conditions prohibiting low to high risk transitions, or forcing high to low risk transitions in a timely manner. A safety module, which is in charge of ensuring that these conditions are observed at run-time, is developed in SIGNAL to explore the applicability of the SIGNAL language to safety-critical design and to establish both the feasibility and the extent of managing safety concerns in an application–independent manner.

Multimedia and spatial information systems

Spatial information systems increasingly require incorporation of multimedia data types. Pictures, sounds, animated sequences, and unstructured text may form an integral part of geographically located entities in information systems. An example ecological application with extensive multimedia requirements illustrates how multimedia data can be integrated with spatial information systems in a generic, application-independent manner.

Unified approaches to integrated-service networks–burst and fast packet switching

The increasing demand for communication services, coupled with recent technological advances in communication media and switching techniques, has resulted in a proliferation of new and expanded services. Currently, networks are needed which can transmit voice, data and video services in an application-independent fashion. Unified approaches employ a single switching technique across the entire network bandwidth, thus allowing services to be switched in an application-independent manner. This paper presents a taxonomy of integrated-service networks, including a look at NISDN, while focusing on unified approaches to integrated-service networks. The two most promising unified approaches are burst and fast packet switching. Burst switching is a circuit switching-based approach which allocates channel bandwidth to a connection only during the transmission of ‘bursts’ of information. Fast packet switching is a packet switching-based approach which can be characterized by very high transmission rates on network links and simple, hard-wired protocols which match the rapid channel speed of the network. Both approaches are being proposed as possible implementations for integrated-service networks. We survey these two approaches, and also examine the key performance issues found in fast packet switching. We then present the results of a simulation study of a fast packet switching network.

Conspiracy numbers

McAllester's conspiracy numbers algorithm is an exciting, new minimax search procedure that builds trees to variable depths in an application-independent manner. The algorithm selectively expands nodes in the tree trying to narrow the range of plausible minimax values at the root of the search tree. It does so by computing the conspiracy number for each possible root value; the minimum number of leaf nodes that must change their score to cause the root to change to that value. This paper describes the algorithm and presents an implementation in a computer chess program. Experimental results give rise to optimism about the algorithm's future, although there are still some serious problems to be overcome.