An enhanced zone 3 algorithm of a distance relay using transient components and state diagram

Zone 3 of a distance relay is used to provide the remote backup protection in case of the failure of the primary protection. However, the risk of maloperation under stressed conditions such as heavy loading, voltage, and transient instability is quite high. Zone 3 is used in combination with the derivatives of the voltage and current, etc. to prevent maloperation. At times, the impedance characteristics that restrict the tripping area of relay are used to avoid maloperation due to load encroachment. This work presents a novel zone 3 scheme based on combining the steady-state components (i.e., 60 Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operate correctly for the various events.     

Preparation of a sensor substrate using functionalized mesoporous silica on a gold film for surface plasmon resonance (SPR) spectroscopy

The use of surface plasmon resonance (SPR) spectroscopy has been applied to a wide variety of fields such as biosensors and surface analysis instruments. In general, a SPR substrate is prepared using self-assembled monolayer (SAM) method of organic molecules as receptor for the target on a layer of gold or silver. However, mesoporous inorganic materials such as SBA-15 have benefits as sensor substrate for SPR. Mesoporous silica has a large surface area which receptor molecule can be attached and has a rigid body which has an excellent stability in the extreme condition compared to organic sensing layer. We prepared an organic modified mesoporous silica and successfully immobilized it on a gold surface, in an attempt to use as a substrate for SPR spectroscopy. For the comparison of sensitivity of prepared substrate, Pt²⁺ detection was selected as a model system. Substrate prepared in this study exhibited the capability of selective sensing for Pt²⁺ ions.     

Carbide Formation and Growth Kinetics Enhanced by Tensile Stress and Elevated Temperature Intergranular Cracking in 2.25Cr-1.5W Heat-Resistant Steels

The carbide growth kinetics enhanced in grain interiors is mainly due to the increased diffusivity in the direction normal to the tensile stress. The accelerated kinetics at the grain boundaries normal to the tensile stress is due to the increased grain boundary energy and the widened grain boundary path producing the increased diffusivity in the direction normal to the tensile stress. A strong segregation behavior of impurities to the grain boundary carbide interfaces follows the enhanced grain boundary carbide growth kinetics.     

Activity-Sensitive Flip-Flop and Latch Selection for Reduced Energy

This paper presents new techniques to evaluate the energy and delay of flip-flop and latch designs and shows that no single existing design performs well across the wide range of operating regimes present in complex systems. We propose the use of a selection of flip-flop and latch designs, each tuned for different activation patterns and speed requirements. We illustrate our technique on a pipelined MIPS processor datapath running SPECint95 benchmarks, where we reduce total flip-flop and latch energy by over 60% without increasing cycle time.     

An improved deep submicrometer MOSFET RF nonlinear model with newbreakdown current model and drain-to-substrate nonlinear coupling

An improved deep submicrometer (0.25 μm) MOSFET radio-frequency (RF) large signal model that incorporates a new breakdown current model and drain-to-substrate nonlinear coupling was developed and investigated using various experiments. An accurate breakdown model is required for deep submicrometer MOSFETs due to their relatively low breakdown voltage. For the first time, this RF nonlinear model incorporates the breakdown voltage turnover trend into a continuously differentiable channel current model and a new nonlinear coupling circuit between the drain and the lossy substrate. The robustness of the model is verified with measured pulsed I-V, S-parameters, power characteristics, harmonic distortion, and intermodulation distortion levels at different input and output termination conditions, operating biases, and frequencies     

A Novel Two-Step Channel-Prediction Technique for Supporting Adaptive Transmission in OFDM/FDD System

This paper introduces a novel channel-prediction technique for an orthogonal frequency-division multiplexing (OFDM)/frequency-division duplex (FDD) system to support an adaptive-modulation and coding (AMC) scheme over a rapidly time-varying multipath fading channel. Most channel-prediction techniques assume that there is no channel variation in the predefined time duration, e.g. the slot. As a result, those techniques cannot compensate for the degradation of packet-error-rate (PER) performance, resulting from the rapid channel variation over the slot duration. In this paper, we propose a novel two-step channel-prediction technique that considers the time-varying nature of a channel over the duration of interest. Simulation results show that the AMC scheme of the OFDM/FDD system utilizing the proposed channel-prediction technique can guarantee the target PER of 1% without any loss of system throughput compared with a case supported by a conventional channel prediction under ITU-R Veh A 30 km/h.     

Molecular beam epitaxy growth of TmP/GaAs and transistor action inGaP/TmP/GaAs heterostructures

The growth of thulium phosphide (TmP) by molecular beam epitaxy (MBE) on GaAs substrate is reported. Good epilayer quality was demonstrated through X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) analysis. The closely lattice matched TmP layer was n-type with an electron concentration of 1.6×10²¹ cm^-3 and a room temperature mobility of 4.8 cm²V^-1s^-1. The Schottky barrier height determined from 1/capacitance² (1/C²) versus voltage (V) measurements is about 0.81 eV which agrees well with the value obtained through the current-voltage (I-V) measurements. In this work, we also report transistor action in a GaP/TmP/GaAs structure, for which chemical bonding techniques were employed. From I-V measurements, a common base current gain α≈0.55 at V_CB=0 was obtained at room temperature     

Enhanced carrier mobility and photon-harvesting property by introducing Au nano-particles in bulk heterojunction photovoltaic cells

In this study, polymer solar cells (PSCs) doped with Au nanoparticles (Au NPs) were successfully fabricated to maximize the photon-harvesting properties on the photoactive layer. In addition, a conductivity-enhanced hybrid buffer layer was introduced to improve the photon absorption properties and effectively separate the generated charges by adding Au NPs and dimethylsulfoxide (DMSO) to the PH 500 as a buffer layer. The PSC performance was optimized with a 88% improvement over the conventional PSCs (photoactive area: 225 mm², power conversion efficiency (PCE): 3.2%) by the introduction to the buffer layer of Au NPs and DMSO at 10 wt% and 1.0 wt%, respectively, and with 15 wt% Au NP doping in the photoactive layer. The internal resistance was decreased due to the increased photocurrent caused by the localized surface plasmon resonance (LSPR) effect of the Au NPs in the photoactive layer and by the improvement of carrier mobility induced by the DMSO doping of the buffer layer. As a result, the series resistance (R_S) deceased from 42.3 to 19.7 Ω cm² while the shunt resistance (R_SH) increased from 339 to 487 Ω cm².     

A Fast Computation Method in Frequency Domain for Power Ground Plane Impedance Calculation Using the Mobius Transform

A new method to reduce the computation time in power/ground-plane analysis is proposed. The proposed method is based on an approximation of impedance in the frequency domain using Mobius transform. The power/ground plane impedance is transformed by Mobius transform and is more linear than the raw impedance, which ensures that a simple approximation is possible. After the approximation, an inverse Mobius transform is applied to predict the power/ground plane impedance. This method displays the high speed of computing with good accuracy. In the case of impedance calculation for a 17.78 cm times 10.16 cm printed circuit board (PCB) board, the proposed method has shown to be 12 times faster than conventional methods. This method can be applied to the analysis and design of power/ground-plane where complex computation is needed.     

A 400-mA current-mode buck converter with a self-trimming current sensing scheme

A current-programmed mode (CPM) controller is designed for improved DC–DC converter control. The key building block of the CPM controller is an accurate current-sensing circuit. This paper proposes a lossless current-sensing technique to measure the inductor current by measuring the current through the power transistor. A self-trimming circuit is used to compensate for any inaccuracies caused by voltage and temperature variations. The measurement results validate the operation of the fabricated chip.