In this article, we deal with enhancing the accuracy of the sampling instant of micro phasor measurement units ( μ PMUs) used in distribution grids. The pulse per second (PPS) signal of the global positioning system (GPS) synchronizes the start of each second of all μ PMUs in the grid. The internal clock of each μ PMUs then takes over and determines the sampling instants till the next PPS. Due to the inaccuracy and drift of the clock and the unavoidably needed fractional count of the clock pulses, accumulation of error leads to excessive phase error. A lightweight algorithm is proposed for the correction of the sampling period. The algorithm fine-tunes the timer count used to determine the sampling instant. As the proposed algorithm aims at correcting the sampling instant, it can be applied by any other platform, but it needs an accurate time reference like that of the 1 PPS of the GPS. The performance evaluation shows that the maximum phase error is lower than the accepted phase error by about two orders of magnitude. The theoretical results are confirmed by implementing the algorithm on a prototype μ PMU.
Self-learning is receiving great attention internationally in different fields, along with the best utilization of different computational applications or methods. This paper introduces a novel computational approach for supporting Architectural Design Education (ADE) in its early stages; a computational implementation through MATLAB has been developed to conduct the proposed processes. As a scope, spaces’ furnishing design has been selected to demonstrate the proposed computational approach and implementation, while office workspaces have been selected as a representative case. However, the proposed approach provides and enhances ADE through three main concepts:(a)generating design alternatives for different cases of furnishing spaces, (b) providing accurate and flexible evaluations to students’/designers’ works with different levels, and (c) tracking students based on their defaults and relevant sensitive modifications. Different applications of the proposed approach have been generated, analyzed, and validated.
This paper introduces a design of planar array of multiband microstrip antennas for purposes of medical microwave imaging. The target application is breast microwave tomography. The proposed array achieves low level mutual coupling between its elements which is an important parameter for signal integrity during imaging process. Measurements done in the near field regions as in the case of medical imaging are affected greatly by the elements mutual coupling. The proposed array satisfies that requirement. The achieved low coupling level is reached through suitable orientation of each individual element and a wise choice of elements separation and array geometry.
In this paper, a design of multi-band microstrip antenna working as a transceiver in 0.5 ~ 3.8 GHz frequency range enhancing an imaging system of breast interior is presented. The slot loading technique is used to obtain multiple operating bands in the desired frequency range. The design procedure depends on parametric studies to choose best slots locations, widths and inter-separations for best performance. The aim is to obtain as many resonances as possible in the band of breast imaging. Having the most optimum design obtained, the antenna is fabricated and its characteristics are illustrated with a discussion of its potential use in a whole breast imaging system.
In-place analysis for offshore platforms is essentially required to ensure the structural integrity of platform components under extreme environmental conditions. The pile soil interaction is of great concern in structural behaviour of jacket-type fixed offshore platforms. Numerical modelling of a case-study platform with soil-pile-jacket-structure interaction is developed, the pile response demands in terms of lateral displacement and maximum bending moment and shear force, as well as soil reaction are investigated. The topsoil layers have important effects on the responses of the platform and supporting piles. A decrease in the upper soil layers’ resistance leads to higher lateral displacement responses at platform base and a decrease in the shear force and bending moment along the pile shaft. The response results of the soil-structure interaction model of the jacket foundation, confirm that the flexible foundation model simulation is necessary to estimate the loads and response demands of the offshore platform well.
Offshore platforms in seismically active areas must be designed to survive in the face of intense earthquakes without a global structural collapse. This paper scrutinizes the seismic performance of a newly designed and established jacket type offshore platform situated in the entrance of the Gulf of Suez region based on the API-RP2A normalized response spectra during seismic events. A nonlinear finite element model of a typical jacket type offshore platform is constructed taking into consideration the effect of structure-soil-interaction. Soil properties at the site were manipulated to generate the pile lateral soil properties in the form of load deflection curves, based on API-RP2A recommendations. Dynamic characteristics of the offshore platform, the response function, output power spectral density and transfer functions for different elements of the platform are discussed. The joints deflection and acceleration responses demands are presented. It is generally concluded that consideration of the interaction between structure, piles and soil leads to higher deflections and less stresses in platform elements due to soil elasticity, nonlinearity, and damping and leads to a more realistic platform design. The earthquake-based analysis for offshore platform structure is essential for the safe design and operation of offshore platforms.
To mitigate the trade-off between gain and bandwidth of CMOS multistage amplifiers, a receiver front-end (FE) that employs a high-gain narrowband transimpedance amplifier (TIA) followed by an equalizing main amplifier (EMA) is proposed. The EMA provides a high-frequency peaking to extend the FE’s bandwidth from 25% to 60% of the targeted data rate (fbit). The peaking is realized by adding a pole in the feedback paths of an active feedback-based wideband amplifier. By embedding the peaking in the main amplifier (MA), the front-end meets the sensitivity and gain of conventional equalizer-based receivers with better energy efficiency by eliminating the equalizer stages. Simulated in TSMC 65 nm CMOS technology, the proposed front-end achieves 7.4 dB and 6 dB higher gain at 10 Gb/s and 20 Gb/s, respectively, compared to a conventional front-end that is designed for equal bandwidth and dissipates the same power. The higher gain demonstrates the capability of the proposed technique in breaking the gain-bandwidth trade-off. The higher gain also reduces the power penalty incurred by the decision circuit and improves the sensitivity by 1.5 dB and 2.24 dB at 10 Gb/s and 20 Gb/s, respectively. Simulations also confirm that the proposed FE exhibits a robust performance against process and temperature variations and can support large input currents
The integration of optical receivers in nanoscale CMOS technologies is challenging due to less intrinsic gain and more noise compared to SiGe BiCMOS technologies. Recent research revealed that low-noise, high-gain, and low-power CMOS optical receivers can be designed by limiting the bandwidth of the front-end followed by equalization techniques that benefit from good switching characteristics offered by CMOS technologies. In this tutorial brief, the operation of decision-feedback equalization, feed-forward equalization, and continuous-time linear equalization is reviewed in the context of high baud-rate 2-PAM and 4-PAM modulation. Recent advances and techniques in 4-PAM optical receivers are reviewed and compared in terms of speed, sensitivity, bandwidth, and efficiency.