p. torkzadeh

A novel bias regulator circuitry is introduced for the class-C LC-VCO in this paper, that results in reduced phase noise and amplitude-enhanced and more robustness of start-up than conventional class-C VCO. Setting the bias voltage is such that in the start-up, Vbias to be larger than the threshold voltage and provide a safe start-up, then in the steady state oscillation, it goes less than Vth and increases the maximum oscillation amplitude. In the proposed bias circuitry, by combining the ring oscillator circuit and a rectifier and two inverters in the first stage, a step voltage signal is created which changes from 0 to VDD and then by applying it to the second stage and the switching operation of the transistors in this stage, the appropriate Vbias is provided. The proposed VCO is implemented in RF 0.18um CMOS process and is simulated by Cadence. Based on the post layout simulations results, the phase noise of the proposed VCO is -121.3dBc/Hz at 1MHz offset frequency from a 5GHz carrier and the power consumption is 2mW, resulting in a FoM of 192.24dBc/Hz.

Programmable logic devices, such as Field Programmable Gate Arrays, are well-suited for implementing biologically-inspired visual processing algorithms and among those algorithms is HMAX model. This model mimics the feedforward path of object recognition in the visual cortex.

HMAX includes several layers and its most computation intensive stage could be the S1 layer which applies 64 2D Gabor filters with various scales and orientations on the input image. A Gabor filter is the product of a Gaussian window and a sinusoid function. Using the separability property in the Gabor filter in the 0° and 90° directions and assuming the isotropic filter in the 45° and 135° directions, a 2D Gabor filter converts to two more efficient 1D filters.

The current paper presents a novel hardware architecture for the S1 layer of the HMAX model, in which a 1D Gabor filter is utilized twice to create a 2D filter. Using the even or odd symmetry properties in the Gabor filter coefficients reduce the required number of multipliers by about 50%. The normalization value in every input image location is also calculated simultaneously. The implementation of this architecture on the Xilinx Virtex-6 family shows a 2.83ms delay for a 128×128 pixel input image that is a 1.86X-speedup relative to the last best implementation.

In this study, a hardware architecture is proposed to realize the S1 layer of the HMAX model. Using the property of separability and symmetry in filter coefficients saves significant resources, especially in DSP48 blocks.    The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.

In structural analysis, the base of structures is usually assumed to be completely rigid. However, the combination of foundation and the subsurface soil, makes in fact a flexible-base for the soil-structure system. It is well-known that the structural responses can be significantly affected by incorporating the Soil-structure Interaction (SSI) effects. The aim of the present study is to provide more accurate structural responses analysis by considering the influence of SSI. It is noteworthy that the input ground motion records imposed to the combination of the soil, foundation and structure were selected in a such way that their characteristics were completely matched with the subsurface soil of structures. For this purpose, 3, 6, 9, 12, 15, 18 and 20-storey structures resting on a shallow foundation were selected and the concept of Beam on Nonlinear Winkler Foundation (BNWF) model is employed. The seismic responses of these structures were calculated based on the five different types of soil and the outcomes were compared with those from fixed-base structures. A set of 35 ground motion excitations recorded on different soil types, is selected which categorized to 5 sets consist of 7 records. Non-Linear Response History Analysis (NL-RHA) was performed and radiation damping considered for all of the structures and soil types. The results clearly showed that the inter-storey drift ratio was reduced in lower stories considering SSI effects. These effects are strongly increased, especially with increasing the slenderness ratio of the structures and softening the subsurface soil. Finally, the period lengthening ratio of studied structures, for various soil types was investigated.