Electromagnetically coupled coaxial dipole array antenna

A new type of collinear antenna called electromagnetically coupled coaxial dipole array antenna is proposed. The antenna has an advantage of structural simplicity due to a novel use of an electromagnetically coupled feed structure for the radiating element. An analysis of the radiating element is presented and compared with experimental results. Fabrication and measurement of a prototype array antenna are also presented     

Consistency of lumbar discograms of the same disc obtained twice at a 2-week interval: influence of needle tip position

: Although numerous papers have emphasized the importance of accurate needle positioning in lumbar discography, no concrete evidence is available to support this contention, and no study has evaluated the image consistency of discography as influenced by this factor. By observing the consistency of two images in relation to needle tip position we aimed to clarify the importance of needle positioning in discography. One hundred and ninety-two patients (324 discs) receiving steroid intradiscal therapy in whom discography of the same disc was performed twice at a 2-week interval and in whom the needle tip position was within the acceptable range (as defined by us) were studied. The patients were divided into two groups: in group G, in whom the needle tip was within a limited range on both discograms, and group P, in whom the needle tip was in this range on only one discogram. Image consistency was compared roentgenographically in the two groups. The consistent image rate for the total number of discs was 48.5%, being significantly higher in group G (53.2%) than in group P (39.0%). The rates were lower in the nucleus pulposus and the posterior portion of the disc than in the other disc areas, but were significantly higher in group G (85. 4% and 75.0%, respectively, for these two areas). The necessity for accurate needle tip positioning was proved roentgenographically.     

Protein binding effects of salivary excretion of phenobarbital in dogs

The salivary excretion of phenobarbital was investigated by collecting parotid saliva (Pr) and mandibular-sublingual saliva (MS) separately after intravenous administration in beagle dogs. (1) The alterations in the proportions of saliva secreted by the different glands were produced by salivation stimulants such as citric acid, ascorbic acid, sodium chloride and sodium glutamate. (2) The phenobarbital concentrations in both Pr amd MS were lower than those in plasma. The drug concentrations in MS were significantly lower than in Pr with stimulus of 10% citric acid of 15% sodium chloride (p less than 0.05). There was a significant correlation between phenobarbital concentration in each saliva and plasma specimen ( p less than 0.05). (3) The stimulation with 10% citric acid produced higher saliva /plasma drug concentration ratios (S/P ratios: 0.923 +/- 0.175 for Pr, 0.633 +/- 0.073 for MS) than that with 15% sodium chloride (S/P ratios: 0.597 +/- 0.071 for Pr, 0.509 +/- 0.067 or MS). (4) The S/P ratios were hardly influenced by salivary flow rates, at least under the experimental conditions examined in this study. (5) The increased S/P ratios were observed with higher salivary pH and then the equation of Matin et al. 3) seemed to hold for the average values of salivary pH and S/P ratio. (6) The stimulation with 10% citric acid produced higher protein concentration in saliva and higher S/P ratio than that with 15% sodium chloride following alternate stimulations in the same dog.     

Unit commitment by heuristics and absolutely stochastic simulated annealing

A new approach to unit commitment problem is presented using absolutely stochastic simulated annealing method. In every iteration, a solution is taken with a certain probability. Typically in simulated annealing minimisation method, a higher cost feasible solution is accepted with temperature-dependent probability; however, other solutions are accepted deterministically. That may lead to the near optimisation slowly. However, all the solutions of both higher and lower costs, are associated with acceptance probabilities to make an early jump from one local minimum to other so that it can search and compare more local minima within the same time/iteration limit. Besides, the number of bits flipping is decided by the appropriate distribution. Excess units with system-dependent probability distribution handle constraints efficiently. Sensitivity of the distribution parameters is tolerable. To reduce economic load dispatch calculations, a sign bit vector is introduced as well. The proposed method is then tested using the reported problem data set. Simulation results are compared to previous reported results. Numerical results show an improvement in solution cost and time compared to the results obtained from powerful algorithms     

Sensor-less maximum power point tracking control for wind generation system with squirrel cage induction generator

This paper proposes a technique that determines the optimal windmill operation speed and the optimal rotor flux. Moreover, the position and speed sensor-less wind generation system using the electromotive voltage observer to estimate rotor position and full-order observer to estimate rotor speed and the windmill output torque are proposed. The position and speed sensor-less maximum power point of wind power generation system is controlled by using the above estimated values, optimized windmill operation speed for maximum output power and optimized rotor flux for minimum generator losses. The effectiveness of the position and speed sensor-less maximum power point tracking control for wind power generation system with squirrel cage induction generator is verified by simulations. The simulation results confirm that the proposed method can estimate the operation speed efficiently.     

Reactions of carbon black. Part I. Nonthixotropic carbon black compositions

The solution polymerization of butyl acrylate in the presence of a furnace black was found to produce a stable dispersion of carbon black which showed Newtonian flow, while the mixture prepared by mixing the same carbon black into a solution of poly(butyl acrylate) homopolymer had a large degree of thixotropy. A marked change in the viscosity of the reaction mixture was also observed at an early stage of polymerization when the initial mixture which was a moist mass with no fluidity, turned to a fluid easily stirred. The change in viscosity and the transition in flow behavior were carefully followed with a rotary cylinder type viscometer. The non-Newtonian initial mixture was found to turn to a Newtonian fluid at low conversion of the monomer. Beside the adsorption of the homopolymer onto the surface of carbon black particles, which would occur also in mechanical mixing, the change in the flow behavior was estimated to be caused by the change in the shape and the size of the dispersed carbon black particles due to the change in the condition of the surface of the particles by which growing polymer radicals, as well as initiator radicals, were captured.     

High efficiency control of synchronous reluctance motors using extended Kalman filter

High-efficiency control of synchronous reluctance motors (SynRMs) is very important in the sense of energy saving and conservation of the natural environment because the efficiency of the SynRM is generally lower than that of other types of AC motors. This paper presents a high-efficiency control strategy for the SynRMs. In this strategy, the d- and q-axes currents are controlled instantaneously. Since the control performance mainly depends on the accuracy of the machine parameters, online parameter estimation using the extended Kalman filter is incorporated into the control strategy. This control strategy improved the drive efficiency and robust performance against machine parameter variations. The validity of the proposed scheme is demonstrated through experimental results.     

Superior sagittal sinus thrombosis presenting with subarachnoid hemorrhage in a patient with aplastic anemia

A 54-year-old female, who had been treated for aplastic anemia by metenolone acetate since 1981, developed a sudden unconsciousness in September 1995. On admission, she was drowny, CT showed a subarachnoid hemorrhage (SAH) in the right Sylvian fissure. Angiography demonstrated a complete occlusion of the superior sagittal sinus. The SAH was assumed to be originated from rupture of the right Sylvian vein, which was irregularly dilated on angiography. The dural sinus thrombosis was thought to be caused by a long term use of metenolone acetate, and it was discontinued. But her platelet count dropped due to the aggravation of aplastic anemia, and she developed repeated hemorrhagic infarction. An active anticoagulant therapy for the dural sinus thrombosis was thought to be inappropriate because she had the aplastic anemia and the hemorrhagic infarction recurred. We have successfully treated this case by mild anticoagulant therapy with nafamostat mesilate (Futhan).     

Volume-type holographic antenna

A new type of holographic antenna based on the principle of the volume hologram is proposed. The characteristics of the prototype are examined. The antenna has a unidirectional beam with a front-to-back ratio of 20 dB. The practical frequency handwidth is about 10 percent of the center frequency. The antenna is unique in that the feed point is placed in the plane of the holographic plate so that both feeder and the holographic plate could be made out of one printed circuit board for easy flush mount installation or mass production, although the feeder of the prototype antenna was a pyramidal horn.