Magnetic Fluids and Their Use in Transducers

Magnetic fluids are now widely used to implement transducer architectures. These fluids have valuable properties compared to traditional materials. In this column, a brief overview of magnetic fluids and their traditional uses in the field of transducers are given and some applications developed at the DIEES laboratory at the University of Catania, Italy are presented     

Designing for parallel fuzzy computing

As the number of fuzzy logic applications increases, demand for faster architectures will grow. Our design for a VLSI fuzzy processor uses fuzzy inference techniques that optimize processing time. Preprocessing that reduces the number of rules to be processed, parallel computation of active rule degrees of activation, and scalability are major features of this architecture. The journal issue contains a concise summary of this article. The complete article is linked to Micro's home page on the World Wide Web (http://www.computer.org/pubs/micro/micro.htm)     

An evolutionary management scheme in high-performance packet switches

This paper deals with a novel buffer management scheme based on the combination of evolutionary computing and fuzzy logic for shared-memory packet switches. The philosophy behind it is adaptation of the threshold for each logical output queue to the real traffic conditions by means of a system of fuzzy inferences. The optimal fuzzy system is achieved using a systematic methodology based on Genetic Algorithms for membership-function selecting and tuning. This methodology approach allows the fuzzy system parameters to be automatically derived when the switch parameters vary, offering a high degree of scalability to the fuzzy control system. Its performance is close to that of the push-out mechanism, which can be considered ideal from a performance viewpoint, and at any rate much better than that of threshold schemes based on conventional logic. In addition, the fuzzy threshold scheme is simple to implement, unlike the push-out mechanism which is not practically feasible in high-speed switches due to the amount of time required for computation, and above all inexpensive when implemented using current standard technology.     

Performance evaluation of efficient multi-objective evolutionary algorithms for design space exploration of embedded computer systems

Multi-objective evolutionary algorithms (MOEAs) have received increasing interest in industry because they have proved to be powerful optimizers. Despite the great success achieved, however, MOEAs have also encountered many challenges in real-world applications. One of the main difficulties in applying MOEAs is the large number of fitness evaluations (objective calculations) that are often needed before an acceptable solution can be found. There are, in fact, several industrial situations in which fitness evaluations are computationally expensive and the time available is very short. In these applications efficient strategies to approximate the fitness function have to be adopted, looking for a trade-off between optimization performance and efficiency. This is the case in designing a complex embedded system, where it is necessary to define an optimal architecture in relation to certain performance indexes while respecting strict time-to-market constraints. This activity, known as design space exploration (DSE), is still a great challenge for the EDA (electronic design automation) community. One of the most important bottlenecks in the overall design flow of an embedded system is due to simulation. Simulation occurs at every phase of the design flow and is used to evaluate a system which is a candidate for implementation. In this paper we focus on system level design, proposing an extensive comparison of the state-of-the-art of MOEA approaches with an approach based on fuzzy approximation to speed up the evaluation of a candidate system configuration. The comparison is performed in a real case study: optimization of the performance and power dissipation of embedded architectures based on a Very Long Instruction Word (VLIW) microprocessor in a mobile multimedia application domain. The results of the comparison demonstrate that the fuzzy approach outperforms in terms of both performance and efficiency the state of the art in MOEA strategies applied to DSE of a parameterized embedded system.     

An efficient fuzzy system for traffic management in high-speed packet-switched networks

 In this paper we present a novel buffer management scheme based on fuzzy logic. We deal with the problem of managing traffic flows with different priorities within the same buffer. The aim is to guarantee the QoS of high-priority traffic, and at the same time exploit unused buffer resources to accommodate best-effort traffic in order to maximize the total throughput. The scheme we propose can be applied both to ATM and IP networks. The performance evaluation of the fuzzy priority control scheme shows that it outperforms any static threshold mechanism and, as far as the total throughput is concerned, it is very close to that of the push out mechanism considered in literature as an ideal mechanism. Finally, we address some implementation issues of the control system and propose the design of a new cost-effective VLSI fuzzy processor.     

A GA-based design space exploration framework for parameterized system-on-a-chip platforms

The constant increase in levels of integration and reduction in the time-to-market has led to the definition of new methodologies, which lay emphasis on reuse. One emerging approach in this context is platform-based design. The basic idea is to avoid designing a chip from scratch. Some portions of the chip's architecture are predefined for a specific type of application. This implies that the basic micro-architecture of the implementation is essentially "fixed," i.e., the principal components should remain the same within a certain degree of parameterization. Many researchers predict that platforms will take the lion's share of the integrated circuit market. In this paper, we propose an approach based on genetic algorithms for exploring the design space of parameterized system-on-a-chip (SOC) platforms. Our strategy focuses on exploration of the architectural parameters of the processor, memory subsystem and bus, making up the hardware kernel of a parameterized SOC platform for the design of embedded systems with strict power consumption and performance constraints. The approach has been validated on two different parameterized architectures: one based on a RISC processor and another based on a parameterized very long instruction word architecture. The results obtained on a suite of benchmarks for embedded applications are discussed in terms of both accuracy and efficiency. As far as accuracy is concerned, the approach gives solutions uniformly distributed in a region less than 1% from the Pareto-optimal front. As regards efficiency, the exploration times required by the approach are up to 20 times shorter than those required by one of the most efficient and widely referenced approaches in the literature.     

A VLSI fuzzy expert system for real-time traffic control in ATMnetworks

Concerns a fuzzy logic-based system which has been purposely designed to achieve real-time traffic control in high-speed networks using the asynchronous transfer mode (ATM) technique. One of the most critical functions is “policing”, which has the task of ensuring that each user source complies with the traffic parameters negotiated in the call setup to avoid network congestion. This function is difficult to implement on account of certain conflicting requirements such as selectivity and responsiveness. This is confirmed by the severe limits affecting the most popular mechanisms proposed so far, based on conventional logic. The capacity to formalize approximate reasoning processes offered by fuzzy logic is exploited to derive rules of behavior for a policer starting from the know-how of an expert. We address two key issues related to the implementation of the fuzzy policer. The first focuses on the possibility of hardware implementation of the mechanism using VLSI technology; we present the design of a VLSI fuzzy processor which exhibits a level of performance of over 3 MFLIPS. The second issue concerns the suitability of applying the fuzzy policer to the policing of several classes of sources to reach high levels of cost effectiveness and scalability     

A Ferrofluidic Inclinometer in the Resonant Configuration

In this paper, an innovative inclinometer exploiting ferrofluids is presented. The device consists of a glass pipe filled with deionized water and a drop of ferrofluid, a coil generating a retaining force on the ferrofluidic drop, a couple of sensing coils detecting the ferrofluidic mass position, and two exciter coils moving the ferrofluidic drop back and forth inside the water at the resonance frequency of the whole system. The device exhibits an intrinsic robustness against inertial shocks. The resonant operation mode represents the main novelty with respect to previous realizations of the ferrofluidic inclinometer presented by the authors. This strategy allows for improving the performances of the inclinometer also in terms of mechanical sensitivity. This paper will focus on the design and experimental characterization of the resonant inclinometer, showing improvements achieved by the resonant configuration with respect to the previous “static implementation” without the exciter coils.      

An integrated fuzzy-GA approach for buffer management

This paper deals with a novel buffer management scheme based on evolutionary computing for shared-memory asynchronous transfer mode (ATM) switches. The philosophy behind it is adaptation of the threshold for each logical output queue to the real traffic conditions by means of a system of fuzzy inferences. The optimal fuzzy system is achieved using a systematic methodology, based on genetic algorithms (GAs), which allows the fuzzy system parameters to be derived for each switch size, offering a high degree of scalability to the fuzzy control system. Its performance is comparable to that of the push-out (PO) mechanism, which can be considered ideal from a performance viewpoint, and at any rate much better than that of threshold schemes based on conventional logic. In addition, the fuzzy threshold (FT) scheme is simple and cost-effective when implemented using VLSI technology.     

Advanced learning tools: From real needs to useful student support [Instrumentation Notes]

Advanced learning tools that use current technologies such as informatics, electronics, and sensors can improve the efficiency of student laboratory sessions. Based on remote teaching [1], [2] and advanced monitoring tools [3], [4], [5], these laboratories can improve student learning so much that they effectively change the laboratory teaching approach. This "assisted educational activity" can be extended to cover a large set of student and school needs. The main advantages of these systems are: · a large number of students can use the same equipment; · fewer tutors are needed; · scheduling student labs is much easier; · a more effective teaching activity is possible; · they allow distance learning; and · they can be adapted for students with different needs, including the visually impaired. Educational tools discussed in this column that have been developed by researchers at the DIEES department of the University of Catania [6] are a Computer Science Class Teaching Aid for the Visually Impaired, several Virtual Instruments, and online laboratory sessions for electrical and electronic measurement courses. An interactive environment has also been developed to reduce the time needed to write an accurate technical report [3]. A common word processor (PC) used for writing technical papers is connected via the network (either local or Internet) to a host computer that has an interactive set of digital instruments. The PC uses suitable routines implemented in SCPI language (Standard Command for Programmable Instruments) to allow local control of the digital instruments.