Transient analysis of an advanced static var compensator using quad-series voltage-source PAM inverters

This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains.     

Problem pharmaceutical patents

These days, the number of pharmaceutical patent applications which do not specify the principal active ingredient in the form of a chemical name or structure is increasing. These patents are difficult to retrieve in retrospective on-line searches using chemical structures or keywords. Furthermore, even if you could find them, the situation with regard to patentability is obscure and this causes considerable problems for the experts in charge of the patent search. If you are a searcher for a large pharmaceutical company, you might already be apprehensive of infringing such patents. We, the JFA,^* gathered these patents together and studied the differences between their patentability in Japan, the US and the EPO.     

Suppurative lesions without prominent epithelioid cell response in abscess-forming granulomatous lymphadenitis

To clarify the clinicopathological significance of the suppurative lesions without an epithelioid granulomatous response (SLs without Ep) in lymph nodes and their relationship to abscess-forming granulomatous lymphadenitis (AGL) and cat scratch disease (CSD), 10 cases were assessed clinicopathologically and immunohistologically. SLs without Ep were located in the subcapsular sinus, paracortical area and medullary cords, but not in the germinal centers. The microabscesses were surrounded by collections of monocytoid B-lymphocytes (MBLs), histiocytes without epithelioid features, neutrophils, small lymphocytes and small numbers of plasma cells. The majority of the MBLs seen in the SLs without Ep were of the large cell type. The histological triad of toxoplasmic lymphadenitis, i.e., reactive follicular hyperplasia, small clusters of epithelioid cells and aggregates of MBLs, were also seen in all cases. Some of the clinical and pathological findings in our 10 cases were characteristic of CSD, i.e., (1) cat exposure before the lymphadenopathy was in four of the 10 cases, (2) occurrence in autumn and winter months in all cases, (3) typical suppurative granulomas surrounded by palisaded epithelioid cells were in four of the 10 cases, and (4) Warthin-Starry silver stain-positive bacteria were detected in seven of the 10 cases. The results of our study suggest that SLs without Ep are an early stage of CSD.     

Environmental effect on room- temperature ductility of isothermally forged tial- base alloys

Isothermally forged TiAl-base alloys (Al-rich, Mn-containing, and Cr-containing TiAl) were heat-treated in various conditions, and equiaxed grain structures consisting of γ and α₂ or Β phases were obtained. The heat-treated alloys were tensile tested in vacuum and air at room temperature, and the environmental effect on tensile elongation was studied. The ductility of the alloys consisting of equiaxed γ grains and a large amount of α₂ grains was not largely affected by laboratory air, and a decrease in the amount of α₂ grains resulted in a large reduction of ductility in air. The Β phase in the Cr-containing alloy improved the ductility in vacuum, but it resulted in a large reduction of ductility in air. Formerly with Kougakuin University, Shinjyuku-ku, Tokyo, Formerly with National Research Institute for Metals, Meguro-ku, Tokyo,     

Development of 170 GHz/500 kW gyrotron

A development of 170GHz/500kW level gyrotron was carried out as R&D work of ITER. The oscillation mode is TE_31,8. In a short pulse experiment, the maximum power of 750kW was achieved at 85kV/40A. The efficiency was 22%. In the depressed collector operation, 500kW/36%/50ms was obtained. The maximum efficiency of 40% was obtained at P_RF=470kW whereas the power decrease by the electron trapping was observed. Pulse extension was done up to 10s at P_RF=170kW with the depressed collector operation. The power was limited by the temperature increase of the output window.     

Experimental study on a quasi-optical mode converter for transforming the whispering-gallery mode into a circularly polarized hollow radiation beam

An experiment was carried out for transforming the 120 GHz-TE_12.2 whispering-gallery mode (WGM) into a circularly polarized hollow radiation beam. A hollow beam was formed by reflecting the WGM, which was radiated from a 16 mm radius circular waveguide cut, with an annular mirror having suitable local normal vectors. The experimentally observed field intensity profiles of the reflected wave were in good agreement with calculated results.     

A transmit/receive IF chip set for WCDMA mobiles in 0.35 /spl mu/m CMOS

An implementation of the IF section of WCDMA mobile transceivers with a set of two chips fabricated in an inexpensive 0.35-/spl mu/m two-poly three-metal CMOS process is presented. The transmit/receive chip set integrates quadrature modulators and demodulators, wide dynamic range automatic gain control (AGC) amplifiers, with linear-in-decibel gain control, and associated circuitry. This paper describes the problems encountered and the solutions envisaged to meet stringent specifications, with process and temperature variations, thus overcoming the limitations of CMOS devices, while operating at frequencies in the range of 100 MHz-1 GHz. Detailed measurement results corroborating successful application of the new techniques are reported. A receive AGC dynamic range of 73 dB with linearity error of less than /spl plusmn/2 dB and spread of less than 5 dB for a temperature range of -30/spl deg/C to +85/spl deg/C in the gain control characteristic has been measured. The modulator measurement shows a carrier suppression of 35 dB and sideband/third harmonic suppression of over 46 dB. The core die area of each chip is 1.5 mm/sup 2/.     

Cooperative behavior of various agents in dynamic environment

The multi-agent model is a model in which agents with limited ability cooperate each other to accomplish a goal. In this paper, we introduce a multi-agent model in which agents are created to imitate real ants. There are two different type of agents, each type of which has a particular task. We designed agents to communicate each other by using pheromone considering noise. On this model, we observed cooperative behavior of agents and evaluated conditions to make an order of behavior in the model.     

Tissue compatibility of polylactic acids in the skeletal site

This study was undertaken to examine the osseous tissue compatibility of polylactic acid (PLA) with properties of bioabsorbability and plasticity. Two kinds of granular PLA with different molecular weight (PLA-H: 28 000 MW, PLA-L: 10 600 MW) were implanted into rat tibiae and light microscopic sections were prepared at 1, 2, 4, 8, 16, and 24 weeks following surgery. The tissue compatibility of the PLAs was compared with that of hydroxyapatite (HAP) which is a non-absorbable biocompatible material. After implantation, both PLAs were gradually absorbed and replaced by marrow tissue at 24 weeks. PLA-H degraded slower than PLA-L. New bone formation was observed around each PLA by 4 weeks, and a vast amount of bone deposited on PLA-H at 16 weeks. Phagocytic reactions to the PLAs were noted, however, severe inflammation was not seen. HAP was not absorbed and bone surrounded it throughout the experiment. These results indicate good tissue compatibility of PLA as a bioabsorbable material at the skeletal site.