Oxidation of Sintered VТ1-0 Titanium

Materials Science - We compare the results of oxidation of sintered powder titanium and deformed VT1-0 titanium. The differences between the formation of diffusion and oxide layers are detected by...     

Our experience in using the brachial venae comitantes as a native vascular access for hemodialysis

A native arteriovenous fistula is the preferred vascular access for patients on long‐term hemodialysis. In the absence of suitable superficial veins, the deep venous system can be used. We intend to present our experience in using the brachial venae comitantes (VC) to create a native arteriovenous fistula. From January 2012 to December 2014, we utilized the brachial vena comitantes to create 12 arteriovenous fistulae. Data from these 12 subjects were analyzed retrospectively to produce this case series. The average age of our subjects was 55.6 years. Forty‐two percent of the subjects were women. Fifty percent of the subjects had diabetes mellitus and 58% had hypertension. We achieved a functional patency rate of 58% at 1 month's follow up after maturation. The brachio–brachial vena comitans fistula is a safe and plausible option in patients with no other suitable veins for a native fistula, more so in the hands of experienced surgeons. The longer time to cannulation has to be taken into consideration when creating a VC fistula. In suitable patients with end‐stage renal disease, it can delay the use of an arteriovenous graft or a tunneled central venous catheter.     

治理深圳河第四期工程——可持续发展兼生态友好型新措施

深圳河是香港特别行政区和深圳经济特区之间的界河。为解决深圳河的防洪排涝问题,深圳市治理深圳河办公室和香港特别行政区政府渠务署致力于找出可持续发展的方法,以拓宽河道,治理水浸问题。本项目综合运用了最先进的一维、二维数学模型以及实体模型模拟泄洪设计,包括进水口溢流堰系统、出水口水闸和一个80 000 m3的开放式滞洪区。滞洪区的设计运用可持续发展理念,巧妙的湿地设计能够预防水土流失,支持生态发展,优化了泄洪方案。研究成果可为河道治理工程提供参考。     

Development of the titanium structure in explosive collapse of thick-walled cylinders

The dependence of the titanium structure on the total deformation in the explosive collapse of thick-walled cylinders is studied. It is shown that structure evolution as a whole and the critical parameters for the appearance of an unstable plastic flow in titanium are not the functions of the final deformation of the cylinders. This instability, which is governed by the internal structure of the material, is the principal mechanism of the loss of the axial symmetry of collapse in the given geometry under specified load conditions. It is found that the instability of the plastic flow in titanium is manifested in the formation of adiabatic-shear bands. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 5, pp. 122–129, September–October 1998     

Parameter Modeling for Wafer Probe Test

This paper presents the simulation of parameters for wafer probe test by finite-element modeling with consideration of probe over-travel (OT) distance, scrub, contact friction coefficient, probe tip shapes, and diameter. The goal is to minimize the stresses in the device under the bond pad and eliminate wafer failure in probe test. In the probe test modeling, a nonlinear finite-element contact model is developed for the probe tip and wafer bond pad. Modeling results have shown that the probe test OT, probe tip shape and tip diameters, contact friction between the probe tip and bond pad, as well as the probe scrub of the probe tip on bond pad are important parameters that impact the failure of interlayer dielectric (ILD) layer under bond pad. Comparison between probe test damage and wire bonding failure shows the degree of damage to both probe test and wire bonding on the same bond pad structures. In addition that, a design of experiment (DOE) probe test with different ILD and metal thickness is carried. The correlation between the modeling and the DOE test is studied. The results show that the modeling solution agrees with the DOE probe test data. Modeling results have further revealed that probe test can induce the local tensile (or bending) first principal stress in ILD layer, which may be a root cause of the ILD failure in probe test.     

Super-wideband monopolar patch antenna

A monopolar patch antenna for wideband operation is presented. it has super-wide impedance bandwidth from 0.77 GHz to more than 20 GHz for SWR 2. Conical radiation patterns are observed. also, it has a low profile of 0.087 free space wavelength at the lower cutoff frequency, 0.77 GHz, of this bandwidth. moreover, it possesses high peak gain and average gain of 9.5 and 6.1 dbi, respectively.     

GA-based fuzzy logic control of a solar power plant using distributed collector fields

A novel genetic algorithm (GA) based fuzzy logic control (FLC) system has been developed for the solar power plant, Plataforma Solar de Almería (PSA) at Tabernas, in Almería, Spain. The rule base encompasses an empirical set of 49 “if-then” rules. Chromosomes consisting of 49 genes of 5-bit data are created to link to the rule base. The 5-bit data of each gene represents the stength of the corresponding ‘If-Then’ rule. The GA performs the basic operations of reproduction, crossover and mutation on a pool of chromosomes to search for the best rule base which optimises the response time of the plant to input temperature or power demand by controlling the distributed collector field of the plant. The collect field is essentially an array of parabolic mirrors and oil pipes in which the transversal of solar energy takes place. Simulation results on the plant with an optimised rule-base using the 100th generation of the chromosome show that the proposed GA-FLC scheme gives a better and more robust performance of the plant than other schemes previously implemented.     

U-slot patch antenna with shorting pin

Simulation and experimental results are presented for U-slot patch antennas with a shorting pin. The patch area is a fraction of the regular U-slot patch while the impedance bandwidth is over 10%     

Leaky wave antenna based on image NRD guide with staircase-shapeddielectric slab

A leaky wave antenna based on the use of an asymmetric image nonradiative dielectric (NRD) guide has been studied experimentally. By using a staircase-shaped image NRD guide, the gain bandwidth of the antenna becomes three times that of a leaky wave antenna using an ordinary image NRD guide. Moreover, this antenna employs a flared horn in the NRD guide which makes the H-plane beamwidth controllable     

Experimental study of a microstrip patch antenna with an L-shapedprobe

The L-shaped probe is shown to be an attractive feed for the thick microstrip antenna (thickness around 10% of the operating wavelength). A parametric study on the rectangular patch antenna is presented. It is found that the antenna attains 36% impedance bandwidth (SWR⩽2) as well as gain bandwidth and about 7-dBi average gain. A two-element array fed by L-probes is also proposed. Experiments show that the array design can substantially suppress the cross polarization of the proposed antenna. Both the antennas have stable radiation patterns across the passband. Moreover, the measured resonant frequencies of the proposed antenna agree well with an existing formula and the L-probe does not have much effect on the resonant frequency