Optimum Design of Impedance Simulator for Phased Array Antnnas

The impedance of a solid state active phased array antenna varing with frequency and beam scanning scanning angle be matched with the solid state active matching network (SSAMN). In order to adjust and measure the radar conveniently and Securely, it is necessary for the impedance of the simulator of the phased array antennas to be optimized.Having selected the PIN dilde controlling circuits and the circuit parameters optimized,the simulator circuit is determined through numerical computation The experiment is given in support of the simulation.

Adaptive impedance matching using quantum genetic algorithm

An adaptive technique adopting quantum genetic algorithm （QGA） for antenna impedance tuning is presented. Three examples are given with different types of antenna impedance. The frequency range of the dual standards is from 1.7 to 2.2 GHz. Simulation results show that the proposed tuning technique can achieve good accuracy of impedance matching and load power. The reflection coefficient and VSWR obtained are also very close to their ideal values. Comparison of the proposed QGA tuning method with conventional genetic algorithm based tuning method is Moreover, the proposed method can be useful for software wireless bands. also given, which shows that the QGA tuning algorithm is much faster. defined radio systems using a single antenna for multiple mobile and

Enteric neuropathology of congenital intestinal obstruction:A case report

Experimental evidence indicates that chronic mechanical sub-occlusion of the intestine may damage the enteric nervous system （ENS）, although data in humans are lacking. We here describe the first case of enteric degenerative neuropathy related to a congenital obstruction of the gut. A 3-year and 9-mo old girl began to complain of vomiting, abdominal distension, constipation with air-fluid levels at plane abdominal radiology. Her subsequent medical history was characterized by 3 operations： the first showed dilated duodeno-jejunal loops in the absence of occlusive lesions; the second （2 years later） was performed to obtain full-thickness biopsies of the dilated intestinal loops and revealed hyperganglionosis at histopathology; the third （9 years after the hyperganglionosis was identified） disclosed a Ladd＇s band which was removed and the associated gut malrotation was corrected. Repeated intraoperative full-thickness biopsies showed enteric degenerative neuropathy along with reduced interstitial cells of Cajal network in dilated loops above the obstruction and a normal neuromuscular layer below the Ladd＇s band. One year after the latest surgery the patient tolerated oral feeding and did well, suggesting that congenital （partial） mechanical obstruction of the small bowel in humans can evoke progressive adaptive changes of the ENS which are similar to those found in animal models of intestinal mechanical occlusion. Such ENS changes mimic neuronal abnormalities observed in intestinal pseudoobstruction.

Insulation System of Power Transformers Behavior Comparison of Mineral Oils and Natural Ester Dielectric Fluids

Paper deals with a comparison of selected properties of several vegetable oil representatives along their accelerated thermal ageing at the temperature of 90 ℃. These properties are compared to two widely used and commercially available mineral transformer oils. A combined insulating system （an oil-paper system） was created with the usage of mentioned oils for measurement purposes. Dissipation factor, capacity and volume resistance are characteristics measured along a thermal ageing of the oil-paper systems. Infrared spectroscopy was used as an additional method. After 1,000 hours of ageing, the dissipation factor of all systems based on vegetable oils did not exceed the value of 0.015. The volume resistance of systems containing mineral oils was approx, twice as high as the volume resistance of those with vegetable oils. The capacity on the other hand was slightly lower in the case of mineral oils application. An experiment also showed that the paper combined with the vegetable oil dries more quickly than in combination with the mineral oil. Infrared spectroscopy has not shown any expressive changes in the chemical structure of aU tested oils yet （up to 1,000 hours of ageing）.

Two cases of duodenal obstruction due to a congenital web

We present two cases of windsock deformity;both were rare in location and one had a rare associated anomaly. In the first case, the windsock was observed in the fourth part of duodenum, causing partial intestinal obstruction. In the second case, the windsock was located in the third part of the duodenum.

Malrotation causing duodenal chronic obstruction in an adult

Congenital duodenal obstruction is rare in adulthood. An unusual presentation of this condition has led to difficult preoperative diagnosis.We present a case of proximal jejunal obstruction by a congenital band in an adult and review the literature.

High Gain Directional Antenna Array for WiMAX Application

A 16 × 16 micro-strip antenna array with high gain characteristic was proposed for the 5.5 GHz W/MAX application. The T-junctions with a power ratio of 2 ： 1 were used to design the feed network. To correct the stepped discontinuity of impedance change in common multi-section impedance transformer, exponential line matching trans- formers were adopted in the WiMAX frequency band. The reflection coefficient was lower than - 15 dB from 5.08 GHz to 5.87 GHz. The measured gain of the antenna array achieved 29.8 dBi on E-plane at 5.8 GHz.

Resistivity in Formation and Decomposition of Natural Gas Hydrate in Porous Medium

A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method,especially in monitoring the nucleation and growth of the NGH. Isovolumetric formation experiment of NGH is performed at 2°C and 7.8 MPa.Before the NGH formation,the initial resistivity is measured to be 4-7Ω·m,which declines to the minimum value of 2-3Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows,the resistivity increases to a great extent,and finally it keeps at 11-13Ω·m,indicating the completion of the formation process.The NGH decomposition experiment is then performed.When the outlet pressure decreases,NGH begins to decompose,accordingly,the resistivity declines gradually,and is at 5-9Ω·m when the decomposition process ends,which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium,and provides an experimental basis for further study on NGH exploitation in the future.

The Application of High-density Resistivity Method to the Evaluation on the Stability of Gongchangling Open Pit＇s Slope

High-density resistivity method is a new, efficient electrical prospecting method, which can complete a two-dimensional （vertical and horizontal） prospecting process, possesses certain imaging functions for the geo-electric structure, and integrates electric profiling method with electric sounding method together. In this paper, the basic principle, data processing, and result explanation and inference of high- density resistivity method are introduced by taking the application of high-density resistivity method to the prospecting project in the slope of Gongchangling Open Pit, Liaoyang. The result of the prospecting result map analysis showed that the prospecting result was basically in line with the actual situation and proved the great significance of high-density resistivity method to the evaluation on the slope stability of Gongchangling open pit.

Impact of Weather Conditions and Dynamic Load Models on Steady State and Dynamic Response of Power System

This paper gives an insight on the effect of transmission line temperature variations, resulting from loading and weather conditions changes, on a power system＇s steady state and dynamic performance. The impact of dynamic load models on system stability is also studied. The steady-state and dynamic stability simulation results of a 39 bus system for constant line impedance （the traditional simulation practice） are compared to the results with estimated, but realistic, temperature varied line impedances using PSLF （positive sequence load flow） software. The modulated line impedances will affect the thermal loading levels and voltage profiles of buses under steady state response, while the dynamic results will show improved damping in electro-mechanical oscillations at generator buses.

辨证分型联合氨氯地平辨治社区高血压随机平行对照研究

[目的]观察辨证分型联合氨氯地平治疗社区高血压疗效。[方法]使用随机平行对照方法,将86例患者按就诊顺序号方法随机分为两组。对照组43例氨氯地平,1次/d,5mg/次。治疗组43例辨证分型治疗,气虚血瘀:益气汤与四物汤;气血亏虚:归脾汤;肝阳上亢;天麻钩藤饮;痰浊中阻:温胆汤;氨氯地平治疗同对照组。连续治疗30d为1疗程。观测临床症状、舒张压、收缩压、不良反应。治疗1疗程(30d),判定疗效。[结果]治疗组显效25例,有效17例,无效1例,总有效率97.78%;对照组显效17例,有效19例,无效7例,总有效率83.72%;治疗组疗效优于对照组(P<0.05)。舒张压、收缩压两组均有改善(P<0.01),治疗组改善优于对照组(P<0.01)。不良反应治疗组低于对照组(P<0.05)。[结论]辨证分型联合氨氯地平辨治社区高血压,疗效满意,无严重不良反应,值得推广。

Effects of mass layer imperfect bonding on the electrical impedance of a quartz crystal microbalance

We study electrically forced vibrations of a crystal plate of AT-cut quartz carrying a thin mass layer operating as a quartz crystal microbalance for mass sensing.The mass layer is imperfectly bonded to the crystal plate with their interface described by the so-called interface-slip model which allows a discontinuity of the tangential interface displacement.Mindlin’s equations for piezoelectric plates are used.An analytical solution is obtained.The electrical impedance is calculated.The effects of an elastic interface and a viscoelastic interface are examined.

Analysis of dipole-like ultra high frequency RFID tags close to metallic surfaces

It is a challenge for passive RFID tags to be mounted on the surface of metal because the parameters of tag antennas,such as the impedance matching,the radiation efficiency and the radiation pattern,are seriously affected by the metallic surface.This paper presents the characteristics of the dipole-like antennas of ultra high frequency(UHF) radio frequency identification(RFID) tags that are placed close to metallic surfaces.The finite element method(FEM) and method of moment(MoM) were used to simulate the changes of the antenna parameters near the metallic surface.Two typical dipole-like antennas close to the metallic surface,a closed loop antenna and a loaded meander antenna,were modeled,and the performance was evaluated.Experiment was carried out and the results were in good agreement with the simulation,showing that a distance of 0.05λ～0.1λ(λ is the free space wavelength) from the metallic surface could make the dipole-like UHF RFID tag performance be acceptable.