Power quality compensation using universal power quality conditioning system

The aim of this letter is to present a universal power quality conditioning system (UPQS) named after a unified power quality conditioner (UPQC), which is extended by adding a shunt active filter at the load side. Its main purpose is to compensate for supply voltage and load current imperfections, such as sags, swells, interruptions, imbalance, flicker, harmonics, reactive currents, and current unbalance. Converter and control analysis is presented together with results showing the UPQS modes of operation.     

Determinants of left ventricular mass in early hypertension

Four modified cyclic hexapeptides, tenuecyclamides A-D (1-4), were isolated along with the known antibiotic, borophycin (5), from the methanol extract of Nostoc spongiaeforme var. tenue (TAU strain IL-184-6). The planar structure of tenuecyclamides A-D (1-4) was determined by homonuclear and inverse-heteronuclear 2D-NMR techniques as well as by high-resolution mass spectrometry measurements. The absolute configuration of the asymmetric centers was studied by Marfey's method for HPLC. The stereochemistry of the asymmetric centers in tenuecyclamides A and B (1 and 2) could not be fully determined, while that of tenuecyclamides C and D (3 and 4) was unambiguously determined.     

交流调速电梯中的电能质量

因为人们越来越多地使用非线性负载，电网中就存在电源质量问题。在交流传动系统中广泛使用功率变换器，由于其非线性的工作运行状态，导致电压发生畸变，从而影响敏感设备的性能。本文试图分析由功率变换器供电的电梯交流传动系统对电源质量的影响。敏感电气设备和电梯交流传动系统都连接到0．4kV输电线路上。因功率逆变器导致的电压畸变能够导致系统故障甚至电气设备中部分元件的损坏。     

Attentional factors and aversiveness ratings in tests of the preparatory-adaptive-response interpretation of reinforcement.

Questions the methodology of recent tests of preparatory-adaptive-response (PAR) theory (i.e., that signaling reduces the aversiveness of noxious stimuli) on the ground that prior instructions to rate the aversiveness of a shock produce a heightened attention toward the UCS and that this attention blocks the normal PAR mechanism. Exps I-III, with a total of 96 undergraduates, involved distractor tasks concurrent with, but unrelated to, the criterion task of rating the intensity of signaled and unsignaled shocks. Despite a variety of distractor manipulations (e.g., time estimation and pattern recognition tasks), results fail to support the attentional-PAR notion. In Exp IV, "attention" was defined by the accuracy of shock ratings and was reduced by having 24 undergraduates rate a distractor shock in addition to a criterion shock. While reduced attention to the UCS was obtained, the critical signaled     

Online control of current-source-type active rectifier usingtransfer function approach

Current-source topology AC/DC converters (buck converters) operated using pulsewidth modulation have significant drawbacks in lack of line current control and AC-side filter damping. Also, an AC-side filter is usually overrated in order to keep harmonic distortion under imposed limits. Discontinuous current at converter line inputs disables the use of current control techniques known from control of voltage-source converters. In order to overcome these problems, an online control method for the buck converter is presented in this paper. This method is based on the AC filter transfer function approach. Such an approach enables a novel solution for line-side filter optimization in the case of hysteresis line current control. This method leads to a filter with minimal apparent power (cost) and the fast and accurate converter's control response. Furthermore, a line current estimation method was developed. It uses only one current sensor at the converter DC side in order to estimate power supply currents. Suggested methods were numerically and experimentally verified     

New inverting integrator with imp1roved high-frequency response

A new active compensated inverting integrator is presented. The proposed integrator has a variable phase shift which is controlled by a resistor. This can be conveniently used in active filters to compensate for the excess phase shift of the operational amplifiers.     

Changes in mechanical properties of dental alloys induced by saliva and oral probiotic supplements

The effects of the saliva and oral probiotic supplements on roughness, friction and microhardness of the stainless steel (SS) and nickel-titanium (NiTi) alloys used in dentistry was studied. The specimens of stainless steel, uncoated, rhodium-coated and nitrided NiTi were exposed to artificial saliva with pH 4.8 and artificial saliva with addition of probiotic supplements containing bacteria Lactobacillus reuteri Prodentis through 28 days. First 5 days specimens were subjected to thermocycling to simulate intraoral conditions, 2500 cycles from 5 °C to 50 °C and the following days to the temperature of the 37±2 °C. Analyses demonstrated that oral probiotic supplements do not influence microhardness, roughness or friction of stainless steel above the influence of saliva. Probiotics increase roughness in NiTi, but without significant influence on friction, while microhardness in NiTi is not influenced. Surface nitriding reduces the influence of probiotics on roughness while rhodium coating increases it.     

A method for PWM rectifier line side filter optimization intransient and steady states

The purpose of this paper is to develop, design and test an overall approach to line side filter optimization for the current type PWM controlled active rectifier and to investigate influence of control system to converters performance and filter size (TkVA). For the instantly predominating offline current rectifier control methods, a line side filter optimization algorithm and corresponding computer program was proposed and developed. It uses both complete transient and steady state, characteristics of system, ensuring minimized individual and total harmonic distortion (according to standards) of line current and a good power factor together with minimum costs. Suggested method was numerically verified through the extensive simulations using SIMULINK toolbox of MATLAB software. Final verification came from the implementation on a prototype. Detailed testing was performed and the proposed algorithm showed satisfying performance under different operating conditions. As far as the authors are aware, the novel contribution coming from this paper is in completing the line side filter optimization algorithm taking into account both transient and steady state of system, power supply demands and the power factor restriction for the offline controlled current type AC/DC converter     

Compressive image acquisition in modern CMOS IC design

Compressive sampling (CS) offers bandwidth, power, and memory size reduction compared to conventional (Nyquist) sampling. These are very attractive features for the design of modern complementary metal‐oxide semiconductor (CMOS) image sensors, cameras, and camera systems. However, very few integrated circuit (IC) designs based on CS exist because of the missing link between the well‐established CS theory on one side, and the practical aspects/effects related to physical IC design on the other side. This paper focuses on the application of compressed image acquisition in CMOS image sensor integrated circuit design. A new CS scheme is proposed, which is suited for hardware implementation in CMOS IC design. All the main physical non‐idealities are explained and carefully modeled. Their influences on the acquired image quality are analyzed in the general case and quantified for the case of the proposed CS scheme. The presented methodology can also be used for different CS schemes and as a general guideline in future CS based CMOS image sensor designs. Copyright © 2013 John Wiley & Sons, Ltd.     

Permanent Magnet Synchronous Generator Cascade for Wind Turbine Application

This paper proposes an energy conversion system for a wind turbine comprising a grid connected permanent magnet synchronous generator and a 20% rated series converter located in its star point. It models the complete system and focuses on the series converter control whose primary function is the active damping of the generator. In addition, this paper addresses the topic of the dc bus voltage control and the dc capacitance sizing of the series converter. Finally, it validates the performance of the proposed system by means of system simulation.