A communication model of broadcast in wormhole-routed networks on-chip

This paper presents a novel analytical model to compute communication latency of broadcast as the most fundamental collective communication operation. The novelty of the model lies in its ability to predict the broadcast communication latency in wormhole-routed architectures employing asynchronous multi-port routers scheme. The model is applied to the Quarc NoC and its validity is verified by comparing the model predictions against the results obtained from a discrete-event simulator developed using OMNET++

Meta-functional languages for hardware design and verification

The approach of embedding hardware description languages in general-purpose languages has been widely explored in the literature and has been shown to aid hardware design and verification. In this paper we explore the use of a meta-functional language reFLect as a host language for a hardware description language. We show how this approach aids the development, analysis and manipulation of embedded objects, whilst at the same time we keep meta-programming features largely invisible to the hardware designer. We illustrate the use of these techniques in supporting circuit placement techniques and automatic model checking of hardware compiler invariants.peer-reviewe

Design and simulation of a 600 GHz RTD oscillator using commercial harmonic balance software

We report on the design and optimisation of a 600 GHz double barrier resonant tunneling diode (RTD) oscillator. Using the simple Esaki equivalent circuit diode model and published DC experimental I-V data, a custom device model was developed and integrated within a commercial harmonic balance (HB) simulator. This technique utilizes a spline interpolation algorithm as part of the device model to determine instantaneous values of device voltage and current when called from within the main HB software. The maximum oscillation frequency for a 5 ohms load was 1.6 THz, whilst optimisation at 600 GHz was achieved with a 15 ohms load, with an output power of 420 micron W. The present technique should facilitate and simplify simulation of both existent and novel non-linear devices in other configurations, such as multipliers, mixers, self- oscillating mixers, etc.peer-reviewe

Integration of sensorimotor mappings by making use of redundancies

Hemion N, Joublin F, Rohlfing K. Integration of sensorimotor mappings by making use of redundancies. In: IEEE Computational Intelligence Society, Institute of Electrical and Electronics Engineers, eds. The 2012 International Joint Conference on Neural Networks (IJCNN). Brisbane, Australia: IEEE; 2012

Reversible de-identification for lossless image compression using reversible watermarking

De-Identification is a process which can be used to ensure privacy by concealing the identity of individuals captured by video surveillance systems. One important challenge is to make the obfuscation process reversible so that the original image/video can be recovered by persons in possession of the right security credentials. This work presents a novel Reversible De-Identification method that can be used in conjunction with any obfuscation process. The residual information needed to reverse the obfuscation process is compressed, authenticated, encrypted and embedded within the obfuscated image using a two-level Reversible Watermarking scheme. The proposed method ensures an overall single-pass embedding capacity of 1.25 bpp, where 99.8% of the images considered required less than 0.8 bpp while none of them required more than 1.1 bpp. Experimental results further demonstrate that the proposed method managed to recover and authenticate all images considered.peer-reviewe

Magnetorheological landing gear: 2. Validation using experimental data

Aircraft landing gears are subjected to a wide range of excitation conditions with conflicting damping requirements. A novel solution to this problem is to implement semi-active damping using magnetorheological (MR) fluids. In part 1 of this contribution, a methodology was developed that enables the geometry of a flow mode MR valve to be optimized within the constraints of an existing passive landing gear. The device was designed to be optimal in terms of its impact performance, which was demonstrated using numerical simulations of the complete landing gear system. To perform the simulations, assumptions were made regarding some of the parameters used in the MR shock strut model. In particular, the MR fluid's yield stress, viscosity, and bulk modulus properties were not known accurately. Therefore, the present contribution aims to validate these parameters experimentally, via the manufacture and testing of an MR shock strut. The gas exponent, which is used to model the shock strut's nonlinear stiffness, is also investigated. In general, it is shown that MR fluid property data at high shear rates are required in order to accurately predict performance prior to device manufacture. Furthermore, the study illustrates how fluid compressibility can have a significant influence on the device time constant, and hence on potential control strategies

Selective virtual capacitive impedance loop for harmonic voltage compensation in islanded microgrids

Parallel inverters having LCL output filters cause voltage distortions at the point of common coupling (PCC) in islanded microgrids when non-linear loads are present. A capacitive virtual impedance loop could be used to provide selective harmonic compensation in islanded microgrids, instead of introducing additional active or passive filters into the system that could compromise the stability of the microgrid. However, the performance of these compensation loops becomes degraded when a virtual resistance is introduced with the aim to improve the overall stability of the parallel inverters. With the capacitive virtual impedance, there is effectively a compromise between the additional stability provided by the virtual resistance and the harmonic compensation due to the virtual capacitance. This paper focuses on overcoming this limitation of the capacitive virtual impedance with additional virtual resistance for selective harmonic compensation in islanded microgrids. Simulation results were given to show the suitability of the proposed algorithms in reducing the voltage harmonics at the PCC.peer-reviewe