Influence of thickness error on the operation of adjustable magneto-optical isolators

We have performed a theoretical study on the case of transmission-type one-dimensional magnetophotonic crystals (MPCs) to establish a practical magneto-optical isolator (MOI) that operates properly even in the presence of construction errors. We have introduced a very thin MPC structure with high transmittance and a large Faraday rotation, with the capability of adjusting to a perfect MOI. A minor thickness error for the individual layers of this MOI may take it from being a perfect MOI; however, its adjustability can provide a stable operation against fabrication errors.     

Design and numerical simulation of an optofluidic pressure sensor

We present a numerical design procedure for an all-optical compact sensor by means of integrating the optofluidic switch polymer interferometers to measure the microfluidic air pressure and flow rate. The design is based on a flexible air gap optical cavity that can generate an interference pattern when illuminated by a monochromatic light. The optical interference pattern directly depends on the pressure. In our numerical simulations, we take the effects of fluid flow rate, solid deformation, and the light interference into account. We use the beam propagation method for simulating the optics and the finite element method for simulating the mechanics. The significance of the proposed sensor lies with its low power consumption, compactness, low cost, and short length. This sensor can operate under pressure range of 0-60±6% Pa at a constant temperature of 20 °C.     

Design of an ultracompact low-power all-optical modulator by means of dispersion engineered slow light regime in a photonic crystal Mach-Zehnder interferometer

We present the design procedure for an ultracompact low-power all-optical modulator based on a dispersion-engineered slow-light regime in a photonic crystal Mach-Zehnder interferometer (PhC MZI), selectively infiltrated by nonlinear optical fluids. The dispersionless slow-light regime enhancing the nonlinearities enabled a 22 μm long PhC MZI to operate as a modulator with an input power as low as 3 mW/μm. Simulations reveal that the switching threshold can be controlled by varying the optofluidic infiltration.     

涂层厚度对消失模铸Al-Si-Cu合金铸件的影响(英文)

对Al-Si-Cu合金进行消失模铸造,研究涂层厚度对Al-Si-Cu合金铸件缺陷、孔隙率和共晶硅间距的影响。结果表明,提高涂层浆料黏度和延长浸渍时间对铸件的完整性和显微组织有影响。薄的涂层有利于模腔充填性能的改善、显微组织的细化和低孔隙度高质量铸件的获得。     

Palestinian experience with sewage sludge utilizing reed beds

Management of sewage sludge is one of the main environmental problems in Palestine. More than 400 m³/day of aerobic sludge and 5000 m³/year of anaerobic sludge are disposed of randomly in the Gaza Strip, creating several environmental and health problems. Because of the political–economic situation, a low cost system for sludge treatment has to be adopted. The results of a pilot project using a reed bed system in the Gaza Strip are promising. Sludge that accumulated in a reed bed system over a 3-year period was found to be well mineralized and composted, and suitable for land application. The water that drained from the reed bed was found to contain very low concentrations of suspended solids (SS) and chemical oxygen demand (COD). This paper presents the results of a 3-year project using a reed bed for sewage sludge treatment in Gaza – Palestine. The quality of drained water and the quality and quantity of accumulated sludge were monitored in two drying beds, one planted with reeds and the other left as a conventional drying bed.     

Synthesis and characterization of polyurethane coatings derived from polyols synthesized with glycerol, phthalic anhydride and oleic acid

Polyester polyols, with various oleic acid contents were used in the preparation of polyurethane (PUR) coatings. The polyols were designated as Alk28, Alk40 and Alk65, in which 28, 40 and 65 represents the percentages of oleic acid in the respective formulations. The physical properties of the polyols such as acid value and hydroxyl value have been determined and the infrared (IR) spectroscopic analysis of the polyols is reported. The polyols were reacted with aromatic isocyanate (toluene 2,4-diisocyanate, TDI) to form PUR coatings. The effects of varied NCO/OH ratio and oleic acid content of polyols on physical properties of PUR coatings on mild steel panel were determined. The characterization of PUR coatings carried out by IR spectroscopic analysis and physico-chemical properties such as drying time, pencil hardness, adhesion properties, solvent resistance and corrosion/chemical resistant determination were reported. The coatings obtained from polyol Alk28, exhibits the best overall properties followed by Alk40. PUR coatings from Alk65 were softer. As the NCO/OH ratio of the coatings increased, there were progressive increases in mechanical and anticorrosive properties for all the coatings. Overall, these studies showed that the material holds promise for use as effective surface coating compound by designing the formulation of the desired performance.     

A Lyapunov theory based UPFC controller for power flow control

Unified power flow controller (UPFC) is the most comprehensive multivariable device among the FACTS controllers. Capability of power flow control is the most important responsibility of UPFC. According to high importance of power flow control in transmission lines, the proper controller should be robust against uncertainty and disturbance and also have suitable settling time. For this purpose, a new controller is designed based on the Lyapunov theory and its stability is also evaluated. The Main goal of this paper is to design a controller which enables a power system to track reference signals precisely and to be robust in the presence of uncertainty of system parameters and disturbances. The performance of the proposed controller is simulated on a two bus test system and compared with a conventional PI controller. The simulation results show the power and accuracy of the proposed controller.     

Power quality analysis of STATCOM using dynamic phasor modeling

Modeling of synchronous static compensator (STATCOM) of a power system based on the dynamic phasor model to investigate the performance of STATCOM for power quality analysis is described. It is compared with electromagnetic transient program (EMTP) like simulation. The dynamic phasor model and electromagnetic transient (EMT) model of the STATCOM including the power system are implemented in Matlab/Simulink toolbox and PSCAD/EMTDC, respectively. STATCOM dynamic phasor model including switching functions and their control system are presented. A satisfactory solution for power quality problems on typical distribution network is analyzed using the dynamic phasor model and EMTP like PSCAD/EMTDC simulation techniques. The simulation results revealed that the dynamic phasor model of STATCOM is in excellent agreement with the detailed time-domain EMT model of PSCAD/EMTDC simulation. The dynamic behavior of STATCOM using phasor model can be applied for analyzing power quality issues. It is found faster in speed and higher accuracy can be obtained and correlates well with PSCAD/EMTDC simulation results.     

Robust low-sensitivity Adaline neuron based on Continuous Valued Number System

In this article Continuous Valued Number System is studied as an alternative method for implementing Analog Neural Networks. Continuous Valued Number System is analog in nature and employs digit level analog modular arithmetic. The information redundancy among the digits allows efficient operations using analog circuitry with arbitrary accuracy. The general operations in this number system are more precise than regular analog operations, thus enabling us to implement large size analog neural networks with more precision. In this article, function evaluation properties of the Continuous Valued Number System are introduced. These key properties are used for developing analog Adaline with a nonlinear activation function. Stochastic modeling of a network of such elements is carried out which indicates that the proposed network has low sensitivity to implementation errors.