Abstract
The paper addresses the problem of decreasing the overshoot for underdamped second-order systems. A new technique to control the overshoot is proposed, which is based on Posicast control and proportional integral and derivative (PID) control, which performs switching between two controllers. The aim is to use open-loop feedforward control to increase tracking performance and PID control to deal with disturbance rejection. It has been shown that the proposed control scheme can have some advantages over the classical approaches without switching capabilities.

Abstract

Abstract
The increasing capability and flexibility of reconfigurable hardware, such as Field-Programmable Gate Arrays (FPGAs), give developers a wide range of architectural choices that can satisfy various non-functional requirements, such as those involving performance, resource and energy efficiency. This paper describes a novel approach, based on an aspect-oriented language called LARA, that enables systematic coding and reuse of optimisation strategies that address such non-functional requirements. Our approach will be presented in three steps. First, this approach is shown to support design space exploration (DSE) which makes use of various compilation and optimisation tools, through the deployment of a master weaver and multiple slave weavers. Second, we present three compilation and synthesis strategies for word-length optimisation based on this approach, which involve three tools: the WLOT word-length optimiser deploying a combination of analytical methods; the AutoESL tool compiling C-based descriptions into hardware; and the ISE tool targeting Xilinx devices. Third, the effectiveness of the approach is evaluated. In addition to promoting design re-use, our approach can be used to automatically produce a range of designs with different trade-offs in resource usage and numerical accuracy according to a given LARA-based strategy. For example, one implementation for a subband filter in an MPEG encoder provides 31% savings in area using non-uniform quantizers when compared to a floating-point description with a similar error specification at the output. Another fixed-point implementation for the gridIterate kernel used by a 3D path planning application consumed 25% less resources when the error specification is increased from 1e-6 to 1e-4.

Abstract
This study aims to design a compact two antennas array on a USB dongle for WLAN 5.8 GHz application (IEEE 802.11n). The proposed antenna adopts an Inverted-L antenna (ILA) structure, which can be easily integrated into an industry product. The two antenna elements are closely spaced and the high isolation between them is achieved by using the neutralization technique. Moreover, the impedance matching of both antennas is improved by introducing one vertical stub on the neutralizing line. In this way, both the isolation between the two antennas and the impedance matching of each antenna can be improved simultaneously. The experimental results show that this antenna has wide operation bandwidth (S11 <-10 dB) from 5.7 to more than 6 GHz with isolation always better than 10 dB. © 2012 IEEE.

Abstract

Abstract
The synthesis and mapping of applications to configurable embedded systems is a notoriously hard process. Tools have a wide range of parameters, which interact in very unpredictable ways, thus creating a large and complex design space. When exploring this space, designers must understand the interfaces to the various tools and apply, often manually, a sequence of tool-specific transformations making this an extremely cumbersome and error-prone process. This paper describes the use of aspect-oriented techniques for capturing synthesis strategies for tuning the performance of applications' kernels. We illustrate the use of this approach when designing application-specific architectures generated by a high-level synthesis tool. The results highlight the impact of the various strategies when targeting custom hardware and expose the difficulties in devising these strategies. © 2012 IEEE.