A solid state direct on line starter for medium voltage inductionmotors with minimized current and torque pulsations

This paper describes a thyristorized static switch which is designed and implemented specifically for frequent direct-on-line starting of medium voltage large induction motors. The circuit configuration chosen utilizes back-to-back connected series thyristor strings on two of the supply lines. Both the starting current and the torque pulsations of the induction motor are minimized by a controlled, nonsimultaneous switching of motor phases to the supply. This reduces the electrical stresses on the power system and the mechanical stresses on the shaft as compared to conventional switching elements. The optimum switching strategy is found by the use of a hybrid mathematical model in ABC/dqO form. The validity of the results obtained for medium voltage, squirrel-cage induction machine are verified by the use of a physical simulator consisting of a low voltage, small induction machine and a shaft torque measuring system. The system has been in operation successfully in an iron and steel plant since 1991     

Landfill Settlement with Decomposition and Gas Generation

A one-dimensional multiphase numerical model is developed to simulate the vertical settlement involving liquid and gas flows in a deformable (settling) municipal solid waste (MSW) landfill. MSW is represented by a chemical composition, and a global stoichiometric reaction is used to estimate the maximum yield of gas generation. Following the general assumption accepted in the literature, the gas generated by waste decomposition is assumed to comprise of methane (CH4) and carbon dioxide (CO2). The gas generation rate follows an exponentially decaying function of time. The gas generation model developed based on a first-order kinetic single-bioreactor approach includes the governing equations of gas migration, liquid flow, and landfill deformation. The Galerkin finite element method is used to solve the resulting equations. The model developed can be used to estimate the transient and ultimate settlements due to waste decomposition and gas generation in MSW landfills. The proposed model can estimate the waste porosity, gas pressure, liquid pressure, gas saturation, liquid saturation, and stress distributions in settling landfills. The results obtained for a deformable landfill are compared with a landfill having a rigid solid skeleton. Due to settlement, the depth of waste is 27% smaller in deformable landfills than that of the rigid ones.     

A low-power 65-nm CMOS mixer linearized with IM2 injection for V2X applications

Analog Integrated Circuits and Signal Processing - In this paper, high linearity, low power down-conversion mixer is presented with a 65-nm CMOS process for vehicle-to-everything (V2X)...     

UHF RF Front-End Circuits in 0.35-μm Silicon on Insulator (SOI) CMOS

In this work, design and measurement results of UHF RF frontend circuits to be used in low-IF and subsampling receiver architectures are presented. We report on three low noise amplifiers (LNA) (i) single-ended (ii) differential (iii) high-gain differential and a double-balanced mixer all implemented in 0.35-μ m SOI (Silicon on Insulator) CMOS technology of Honeywell. These circuits are considered as candidate low-power building blocks to be used in the two fully-integrated receiver chips targeted for deep space communications. Characteristics of square spiral inductors with high quality (Q) factors (as high as 10.8) in SOI CMOS are reported. Single-ended and fully-differential LNA's provide gains of 17.5 dB and 18.74 dB at 435 MHz, respectively. Noise figure of the single-ended LNA is 2.91 dB while the differential LNA's noise figure is 3.25 dB. These results were obtained for the power dissipations of 12.5 mW and 16.5 mW from a 2.5-V supply for the single-ended and differential LNA's, respectively. High-gain low-power differential LNA provides a small-signal gain of 45.6 dB with a noise figure of 2.4 dB at 435 MHz. Total power dissipation of the high gain LNA is 28 mW from a 3.3-V supply. The double-balanced mixer provides a conversion gain of 5.5 dB with a noise figure of 13 dB at 2 MHz IF. The power dissipation of the mixer is 11.5 mW from a 2.5-V supply. The measured responses and the power dissipations of the building blocks meet the requirements of the communications system. The die areas occupied by the single-ended LNA, differential LNA, high-gain LNA and the mixer are 0.6 mm × 1.4 mm, 1 mm × 1.4 mm, 1.4 mm × 1.2 mm and 0.6 mm × 0.9 mm, respectively. Ertan Zencir received the B.Sc. and M.S. degrees in electrical and electronics engineering from Middle East Technical University, Ankara, Turkey, and Ph.D. degree in electrical engineering from Syracuse University, Syracuse, NY in 1995, 1997, and 2003, respectively. He joined the Electrical Engineering and Computer Science Department of University of Wisconsin-Milwaukee as an Assistant Professor in August 2004. 2003). His current research focuses on RFIC and transceiver design for wireless communications. Douglas Te-Hsin Huang was born in Chia-yi Taiwan. He received the B.S. degree in electrical engineering from National Taiwan Ocean University, Kee-lung, Taiwan in 1993, and the M.S. and Ph.D. degrees in electrical engineering from Syracuse University, Syracuse, New York, in 2001 and 2003, respectively. In 2004, he joined Skyworks Solutions Inc., where he is currently an RFIC Design Engineer. His research deals mainly with low-power, infrastructure, analog RFIC, and microwave integrated circuit designs. Besides microwave and semiconductor engineering, Dr. Huang has broad interest in art, music, and philosophy. Ahmet Tekin received his B.S. degree in Electrical Engineering from Bogazici University, Istanbul, Turkey in 2002 and MS degree in Electrical engineering form North Carolina A&T State University, Greensboro, NC. He is currently working towards his PhD degree at University of California, Santa Cruz, CA. He was a Research Assistant at RF Microelectronic Laboratory, North Carolina A&T State University, from 2002 to 2004. He worked on the design of low power UHF transceiver circuits for space applications. He is currently a Research Assistant at Bio-mimetic Microelectronic Systems Laboratory, University of California at Santa Cruz, working on implantable very low power UHF frequency transceiver for a body sensor network. Numan S. Dogan received the B.Sc. degree from Karadeniz Technical University, Trabzon, Turkey, in 1975, the M.Sc. degree from Polytechnic University, New York, in 1979, and the PhD degree from the University of Michigan, Ann Arbor, in 1986, all in electrical engineering. Since 1998, he has been with the Electrical and Computer Engineering Department, North Carolina A&T State University, Greensboro, North Carolina, where he is an Associate Professor. He was a Visiting Faculty Researcher at Air Force Research Laboratory (AFRL), Eglin Air Force Base, Florida, in 1998, and General Electric Corporate Research and Development Laboratory, Schenectady, New York, in 1999. His earlier research interests included microwave and millimeter-wave solid-state devices and circuits, high-temperature electronics, and silicon micromachining. His recent research interests include RF CMOS Integrated Circuits and low-power Medical Implant Communication Systems (MICS) transceivers. Currently he serves as the Chair of the IEEE Central North Carolina Section. In April 2004, he organized “a walking robot competition” for High School Students. He enjoys hiking to Alpine Lakes in the Pacific Northwest and fishing. Ercument Arvas (M'85–SM'89) received the B.S. and M.S. degrees from METU, Ankara, Turkey, in 1976 and 1979, respectively, and the Ph.D. degree from Syracuse University, Syracuse, New York, in 1983, all in Electrical Engineering. Between 1984 and fall of 1987, he was with the Electrical Engineering Department of Rochester Institute of Technology, Rochester, New York. He joined the Electrical Engineering and Computer Science Department of Syracuse University in 1987, where he is currently a Professor. His research interests include numerical electromagnetics, antennas, and microwave circuits and devices.     

Immobilization of a molybdenum-glycine Schiff base complex within the nanocages of zeolite Y with flexible ligand method

Immobilization of a molybdenum-glycine Schiff base complex onto the supercages of zeolite Y was achieved through the flexible ligand method. The prepared material was characterized by different physicochemical techniques. FT-IR spectroscopy confirmed the immobilization of the complex onto the nanocages of zeolite Y. X-ray diffraction analysis revealed that textural properties of zeolite Y support were preserved during the immobilization process. Nitrogen adsorption–desorption analysis demonstrated the decrease in surface area of the prepared material in comparison with parent zeolite Y. Inductively coupled plasma optical emission spectroscopy showed the presence of 0.75 mmol g^?1 molybdenum in the final material. The obtained material exhibited high catalytic activity, stability, and recyclability in the epoxidation of olefins with tert-butylhydroperoxide as oxidant.     

Synergistic effect of the locust bean gum on the thermal phase transitions of κ-carrageenan gels

Synergism between κ-carrageenan and locust bean gum (LBG) was studied using the photon transmission technique. Synergistic effects in these polymeric mixtures strongly affected the physical properties of the gel structure. The transmitted light intensities, I_tr, versus temperature variations were investigated during the gelation and liquefaction processes. Slight synergistic peaks were detected in gel–sol and sol–gel transition temperatures for high κ-carrageenan/LBG ratios (approx. 80/2). Moreover, apparent synergistic peaks were observed in gel–sol and sol–gel transition activation energies for the mixtures approximately with the ratios of 80/10.     

Synthesis, spectral characterisation and antimicrobial activity of new disazo dyes derived from heterocyclic coupling components

Two series of new disazo dyes were prepared by diazotising 4,4'-diaminodiphenylsulphonamide and 4,4'-diaminodiphenylurea and coupling with 3-methyl-1-phenyl-pyrazoline-5-one, 2-methylindole, 8-hydroxyquinoline, 2-phenylindole, 1-methyl-2-phenylindole, 3-amino-1-phenyl-pyrazoline-5-one. These dyes were characterised by ultraviolet–visible, Fourier transform infrared, nuclear magnetic resonance spectroscopic techniques and elemental analysis. The spectral characterisation of the dyes was evaluated with respect to visible absorption properties in various solvents. The effects of acid and base on the visible absorption maxima of the dyes were also reported. In addition, the antimicrobial effect of the dyes was evaluated.     

Heparin-coated poly(hydroxyethyl methacrylate/albumin) hydrogel networks: In vitro hemocompatibility evaluation for vascular biomaterials

Human serum albumin (AL) containing poly(hydroxyethyl methacrylate) (pHEMA; in tube form with an inner diameter of 6 mm) was synthesized for blood-contacting hydrogel networks via UV-initiated photopolymerization at 25°C. Tensile and breaking tests of pHEMA and pHEMA–AL-1–4 hydrogel networks were studied at their equilibrium water content. The mechanical strength of the hydrogel networks was found to be lowered by an increase in the ratio of AL in the polymer networks. To increase the blood compatibility and prevent thrombus formation, the surface of the pHEMA and pHEMA–AL-3 hydrogel compositions were coated with heparin (HEP). Contact-angle studies showed that the polarities (%) of the pHEMA–AL-3 and pHEMA–AL-3–HEP hydrogel networks were significantly increased in comparison with that of pure pHEMA. The fibrinogen adsorption and platelet adhesion were also reduced after the incorporation of AL and HEP into/onto hydrogel networks in comparison with the pure pHEMA control. Blood compatibility tests of the prepared hydrogel networks, which were intended to be used as blood-contacting materials, were examined with various parameters, such as the hemolytic activity, prothrombin time, activated thromboplastin time, and loss of blood cells in blood. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008