Design and verification of an improved experimental platform for stray current in urban rail transit

With the rapid development of urban rail transit,there have been an urgent problem of excessive stray current.Because the stray current distribution is random and difficult to verify in the field,we designed an improved stray current experimental platform by replacing the simulated aqueous solution with a real soil environment and by calculating the transition resistance by measuring the soil resistivity,which makes up for the defects in the previous references.Firstly,the mathematical models of rail-drainage net and rail-drainage netground were established,and the analytical expressions of current and voltage of rail,drainage net and other structures were derived.In addition,the simulation model was built,and the mathematical analysis results were compared with the simulation results.Secondly,the accuracy of the improved stray current experimental platform was verified by comparing the measured and simulation results.Finally,based on the experimental results,the influence factors of stray current were analyzed.The relevant conclusions provide experimental data and theoretical reference for the study of stray current in urban rail transit.

FEM tire model oriented to virtual experiment of off-road vehicle trafficability

In order to estimate the trafficability of off-road vehicles, the linear relationships between the pressure and the stiffness of the tire and the action of the vertical tire force with the viscoelasticity are analyzed. The method to improve the precision of the model by the coefficients is presented. The constitutive equation of the three-parameter linear model and the stiffness matrix of four-node isoparametric elements are derived to construct the FEM （finite element method） tire model in plan stress. A demarcation and verification system is designed based on the six-dimensional wheel force transducer and the vertical tire force is measured under different velocities. The results show that the model and the method proposed are reasonable.

Experimental analysis of the slip sinkage effect based on real vehicle test

To improve the semi-empirical model, the slip sinkage effect is analyzed based on the real vehicle test. A dynamic testing system is used to gain the dynamic responses of wheel-soil interactions, The Gauss-Newton algorithm is adopted to estimate the undetermined parameters involved in the slip sinkage models. Wong＇s original model is compared with three typical slip sinkage models on the prediction performance of a drawbar pull. The maximum error rate, root mean squared error and correlation coefficient are utilized to evaluate the performance. The results indicate that the slip sinkage models outperform Wong＇s model and greatly improve the prediction accuracy. Lyasko＇s model is confirmed as an outstanding one for its comprehensive performance. Hence, the existence of the slip sinkage effect is validated. Lyasko＇s model is selected as an optimal one for the practical evaluation of military vehicle trafficability.

AIRCRAFT FLIGHT SAFETY ANALYSIS IN LOW ALTITUDE AIRSPACE

The low altitude airspace will be open in China, general aviation flights are tremendously increased. Whether aircrafts can fly safely and how to determine the requirements of safety flight are the problems needed to be confirmed. Under this circumstances, based on the international Civil Aviation Organization（ICAO） criteria and the standards made by CAAC, this paper adopts the ＂See and Avoid＂ principle. Under the binding conditions of flight rules, visibility requirements, responding time, the aircraft speed, circle banking angle or the climbing angle, based on its study on aircraft dynamics principles, this paper establishes a mathematical collision avoidance model for head-to-head traffic and crossing converging traffic at the same level. And the safety separation requirements of the aircrafts in low altitude flight are equantitatively analyzed. Finally, the Matlab software is used to analyze the above method. The result shows that the safe traffic avoidance of the converging traffic at the same level meets certain flight conditions, while intersecting the traffic at the same level can safely avoid the collision.

PLC应用于喷泉控制系统的方案设计

采用PLC与计算机组成的喷泉控制系统,充分利用PLC的通信功能和编程特点,实现上位机与下位机之间的通信和控制,由远程计算机与PLC之间进行通信,通过PLC实现对喷泉各种水型和灯光的快速控制;另一方面,利用PLC的自诊断功能,可实现喷泉控制系统的故障诊断,不但缩短了维修时间,而且提高了控制系统的稳定性。

腹腔镜联合肠梗阻导管治疗复杂性粘连性肠梗阻的可行性分析

目的:探讨腹腔镜联合经鼻肠梗阻导管治疗复杂性粘连性肠梗阻的可行性及潜在优势。方法:回顾性收集符合复杂性粘连性肠梗阻纳入标准、经鼻肠梗阻导管治疗后梗阻未缓解并行手术治疗者65例,随机分为腹腔镜治疗组31例,开腹手术治疗组34例。比较两组围手术期安全性及治疗效果间差异。结果:两组患者年龄、性别、ASA评分及手术史等一般资料比较差异均无统计学意义。31例腹腔镜探查患者共中转5例,34例行开腹手术治疗。在术后并发症率、排气时间、进食时间及术后住院时间方面,腹腔镜组优于开腹组,存在统计学差异(P<0.05)。腹腔镜组患者术后随访复发率(7.7%)低于开腹组(14.7%),具备统计学差异。结论:腹腔镜联合肠梗阻导管治疗复杂性粘连性肠梗阻安全、微创、效果可靠,可显著减低术后复发率,可作为复杂性肠梗阻的有效治疗方式。

Expression Profile Changes of Genes Involved in Lipid Metabolism Pathway During Liver Regeneration in Mice

[ Objective ] The aim of the research was to study the expression profile changes of genes involved in lipid metabolism pathway during liver regeneration in mice. [ Method] The CCI4 induced mouse model of liver regeneration was established and the total RNA was isolated from liver tissue of mouse. Then the changes of genes involved in lipid metabolism pathway during different stages of liver regeneration were detected through micro-array chip gene technique and their specific functions were also analyzed. [ Result] Dudng the process of liver regeneration, the expression level of 98 genes involved in lipid metabolism pathway changed, which were divided into eight groups according to change trend. In the mass, the expression of genes was inhibited in the early stage and up-regulated in the late phase. And the gene expression associated with fatty acid synthesis pathway was mainly up-regulated while the catabolic pathway did not change significantly. Most of genes involved in bile acid synthesis pathway were suppressed before 4.5 d and up-regulated after 4.5 d or 7 d. [ Conclusion] During the process of liver regeneration, the genes associated with lipid metabolism are expressed in different trends, and this data should provide a specific range of genes for further studying the regulation effect of lipid metabolism related pathway on liver regeneration.

Capsule endoscopy: Improving transit time and image view

AIM： To evaluate the effect of various methods of small bowel preparation on the transit time and the quality of visualization of the entire small bowel mucosa. METHODS： Ninety-five patients underwent capsule endoscopy （CE） by easily swallowing the capsule. They were divided into three study groups according to the preparation used： group A （n = 26） by polyethylene glycol （PEG） liter or with sodium phosphate （SP） 12 h prior to the CE study; group B （n = 29） by erythromycin 1 h prior to the CE study; and group C （n = 40） without any preparation. Visualization ranged from good to satisfactory to poor. RESULTS： The gastric emptying time in the group prepared with erythromycin was shorter but without statistical significance and the small bowel transit time was unaffected. In elderly subjects prepared by PEG or SP, the gastric emptying time was significantly longer （163.7 rain, P = 0.05）. The transit times of the three sub-groups were not affected by gender or pathology. The grade of cleaning of the entire study group was 3.27±1.1. The erythromycin group presented significantly the worst quality of images （P = 0.05） compared to the other sub-groups. Age, gender, and pathology had no effect on the quality of the cleaning of the small bowel in the sub-groups. One （1.05%） case had no natural excretion. CONCLUSION： Erythromycin markedly reduces gastric emptying time, but has a negative effect on the quality of the image in the small bowel. The preparation of elderly subjects with PEG or SP has a negative effect on the small bowel transit time.

Contrast-enhanced ultrasound evaluation of hepatic microvascular changes in liver diseases

AIM： To assess if software assisted-contrast-enhanced ultrasonography （CEUS） provides reproducible perfu- sion parameters of hepatic parenchyma in patients af- fected by chronic liver disease. METHODS： Forty patients with chronic viral liver dis- ease, with （n = 20） or without （n = 20） cirrhosis, and 10 healthy subjects underwent CEUS and video re- cordings of each examination were then analysed with Esaote＇s Qontrast software. CEUS dedicated software Qontrast was used to determine peak （the maximum signal intensity）, time to peak （TTP）, region of blood value （RBV） proportional to the area under the time- intensity curve, mean transit time （MTT） measured in seconds and region of blood flow （RBF）. RESULTS： Qontrast-assisted CEUS parameters dis- played high inter-observer reproducibility （κ： coefficients of 0.87 for MTT and 0.90 TTP）. When the region of in-terest included a main hepatic vein, Qontrast-calculated TTP was significantly shorter in cirrhotic patients （vs non-cirrhotics and healthy subjects） （71.0 ± 11.3 s vs 82.4±15.6 s, 86.3±20.3 s, P 〈 0.05）. MTIs in the patients with liver cirrhosis were significantly shorter than those of controls （111.9±22.0 s vs 139.4±39.8 s, P 〈 0.05）, but there was no significant difference between the cirrhotic and non-cirrhotic groups （111.9± 22.0 s vs 110.3 ±14.6 s）. Peak enhancement in the patients with liver cirrhosis was also higher than that observed in controls （23.9± 5.9 vs 18.9±7.1, P = 0.05）. There were no significant intergroup differences in the RBVs and RBFs. CONCLUSION： Qontrast-assisted CEUS revealed re- producible differences in liver perfusion parameters during the development of hepatic fibrogenesis.

Stiffness of individual quadriceps muscle assessed using ultrasound shear wave elastography during passive stretching

Background: Until recently it has not been possible to isolate the mechanical behavior of individual muscles during passive stretching. Muscle shear modulus(an index of muscle stiffness) measured using ultrasound shear wave elastography can be used to estimate changes in stiffness of an individual muscle. The aims of the present study were(1) to determine the shear modulus—knee angle relationship and the slack angle of the vastus medialis oblique(VMO), rectus femoris(RF), and vastus lateralis(VL) muscles;(2) to determine whether this differs between the muscles.Methods: Nine male rowers took part in the study. The shear modulus of VMO, RF, and VL muscles was measured while the quadriceps was passively stretched at 3°/s. The relationship between the muscle shear modulus and knee angle was plotted as shear modulus—knee angle curve through which the slack angle of each muscle was determined.Results: The shear modulus of RF was higher than that of VMO and VL when the muscles were stretched over 54°(all p < 0.01). No significant difference was found between the VMO and VL(all p > 0.05). The slack angle was similar among the muscles: 41.3°± 10.6°, 44.3°± 9.1°, and 44.3°± 5.6° of knee flexion for VMO, RF, and VL, respectively(p = 0.626).Conclusion: This is the first study to experimentally determine the muscle mechanical behavior of individual heads of the quadriceps during passive stretching. Different pattern of passive tension was observed between mono-and bi-articular muscles. Further research is needed to determine whether changes in muscle stiffness are muscle-specific in pathological conditions or after interventions such as stretching protocols.

A low-power high-throughput link splitting router for NoCs

In this paper, we propose a technique for lowering the latency of the communication in a NoC （network on chip）. The technique, which can support two qualities of service （QoS）, i.e., the guaranteed throughput （GT） and best effort （BE）, is based on splitting a wider link into narrower links to increase throughput and decrease latency in the NoC. In addition, to ease the synchronization and reduce the crosstalk, we use the l-of-4 encoding for the smaller buses. The use of the encoding in the proposed NoC architecture considerably lowers the latency for both BE and GT packets. In addition, the bandwidth is increased while the power consumption of the links is reduced.

Compact passing algorithm for signalized intersection management based on vehicular network

To improve the traffic efficiency at signalized intersections, a compact passing algorithm is proposed based on a vehicular network. Its basic principle is that several waiting vehicles after the stop line of the considered intersection should simultaneously start in green periods. Thus, more vehicles can pass the intersection in a green period. Then, the having passed vehicles should follow the planned trajectories to enlarge their longitudinal clearances. Phase timing is not considered in the compact passing algorithm, and therefore, the proposed compact passing algorithm can be combined with other algorithms on phase timing to further improve their performances. Several simulations were designed and performed to verify the performance of the proposed algorithm. The simulation results show that the proposed algorithm can increase the number of completed vehicles and decrease the travel time in the signalized intersections managed by fixed-time and vehicle actuated algorithms, which indicates that the proposed algorithm is effective for improving the traffic efficiency at common signalized intersections.

基于UKF的雷达和机载ESM扩维跟踪

为有效提高异类传感器融合跟踪的效果,提出了一种基于UKF的雷达和机载ESM扩维跟踪算法。首先将目标和机载ESM的状态信息组合起来,形成一个高维的状态向量,从而有效抑制滤波中GPS定位误差所带来的影响;接着在此基础上采用UKF来实现目标的定位跟踪,以求进一步减小扩维后线性化误差加大等问题的影响。仿真结果表明,该算法可更好地实现对目标的定位跟踪。

Sensitivity of the suspected blood indicator:An experimental study

AIM： To investigate whether suspected blood indicator （SBI） in capsule endoscopy （CE） is affected by back- ground color and capsule passage velocity. METHODS： Experimental models of the small intestine constructed from paper in a variety of colors were used to simulate the background colors observed in CE im- ages. The background colors studied included very pale yellow, yellow, very pale magenta, light grayish pink, burnt sienna, and deep and dark brown, and red spots were attached inside them. An endoscopic capsule was manually passed through the models. The rate of detection of the red spots by the SBI was evaluated based on the colors of the models and the capsule pas- sage velocities （0.5 cm/s, 1 cm/s, and 2 cm/s）.RESULTS： The rate of detection of the red spots byground color of the model （P 〈 0.001）. Detection rates were highest for backgrounds of very pale magenta, burnt sienna, and yellow, in that order. They were lowest for backgrounds of dark brown and very pale yellow. The rate of detection of red spots by the SBI tended to decrease at rapid capsule passage velocities （1-2 cm/s） compared to slow velocities （0.5 cm/s） for backgrounds of very pale yellow （P = 0.042）, yellow （P = 0.001）, very pale magenta （P = 0.002）, and burnt sien- na （P = 0.001）. No significant differences in the rate of detection were observed according to velocity for light grayish pink （P = 0.643） or dark brown （P = 0.396）. CONCLUSION： SBI sensitivity was affected by back- ground color and capsule passage velocity in the models. These findings may facilitate the rapid detection of bleeding lesions by CE.

Maglev self-excited vibration suppression with a virtual sky-hooked damper

This work addresses the problem of self-excited vibration,which degrades the stability of the levitation control,decreases the ride comfort,and restricts the construction cost of maglev system.Firstly,a minimum model containing a flexible bridge and a single levitation unit is presented.Based on the simplified model,the principle underlying the self-excited vibration is explored.After investigations about the energy transmission between the levitation system and bridge,it is concluded that the increment of modal damping can dissipate the accumulated energy by the bridge and the self-excited vibration may be avoided.To enlarge the equivalent modal damping of bridge,the sky-hooked damper is adopted.Furthermore,to avoid the hardware addition of real sky-hooked damper,considering the fact that the electromagnet itself is an excellent actuator that is capable of providing sufficiently fast and large force acting on the bridge to emulate the influence of the real sky-hooked damper,the technique of the virtual sky-hooked damper is proposed.The principle underlying the virtual sky-hooked damper by electromagnet is explored and the vertical velocity of bridge is estimated.Finally,numerical and experimental results illustrating the stability improvement of the vehicle-bridge interaction system are provided.

Quantum Secure Direct Communication with Authentication Expansion Using Single Photons

In this paper we propose two quantum secure direct communication (QSDC) protocols with authentication.The authentication key expansion method is introduced to improve the life of the keys with security.In the first scheme,the third party, called Trent is introduced to authenticate the users that participate in the communication.He sends thepolarized photons in blocks to authenticate communication parties Alice and Bob using the authentication keys.In thecommunication process, polarized single photons are used to serve as the carriers, which transmit the secret messagesdirectly.The second QSDC process with authentication between two parties is also discussed.

保健饮料银杏枣汁的生产工艺

具有保健作用的银杏叶提取物 ( EGB)、红枣、枸杞子和蜂蜜制成了枣香宜人、酸甜适口、对心脑血管疾病、老年痴呆症、降低血压等有保健作用的饮料。

A New Indicator Cell Line Established to Monitor Bovine Foamy Virus Infection

In order to improve the accuracy for quantitating the bovine foamy virus (BFV) in vitro,we developed a baby hamster kidney cell (BHK)-21-derived indicator cell line containing a plasmid that encodes the firefly luciferase driven by the BFV long terminal repeat promoter (LTR,from-7 to 1012).The BFV titer could be determined by detecting the luciferase expression since the viral trans-activator BTas protein activates the promoter activity of the LTR.One clone,designated BFVL,was selected from ten neomycin-resistant clones.BFVL showed a specific and inducible dose-and time-dependent luciferase activity in response to BFV infection.Although the changes in luciferase activity of BFVL peaked at 84 h post infection,it was possible to differentiate infected and uninfected cells at 48 h post infection.A linear relationship was established between the multiplicity of infection (MOI) of BFV and the activated ratio of luciferase expression in BFVL.Moreover,the sensitivity of the BFVL-based assay for detecting infectious BFV was 10,000 times higher than the conventional CPE-based assay at 48 h post infection.These findings suggest that the BFVL-based assay is rapid,easy,sensitive,quantitative and specific for detection of BFV infection.

Gas concentration monitoring system for small and medium-sized coal mines based on gas-sensing detection and single-chip control

This paper is aimed at the actual conditions of disaster caused by gas in small and medium-sized coal mines. A new gas concentration monitoring system for coal mines is developed on the basis of gas-sensing detection and single-chip control. The monitoring system uses the tin oxide as the main material of N-type semiconductor gas sensors, be- cause it has good sensitive characteristics for the flammable and explosive gas （ such as methane, carbon monoxide）. The QM-N5-semiconductor gas sensor is adopted to detect the output values of the resistance under the different gas con- centrations. The system, designedly, takes the AT89C51 digital chip as the core of the circuit processing hardware structure to analyze and judge the input values of the resistance, and then achieve the control and alarm for going beyond the limit of gas concentration. The gas concentration monitoring system has man）, advantages including simple in struc- ture, fast response time, stable performance and low cost. Thus, it can be widely used to monitor gas concentration and provide early wamings in small and medium-sized coal mines.

Model for the Vaccination against the Poliomyelitis

The poliomyelitis is an acute infection produced by the polio virus that affects the human central nervous system. It is transmitted by fecal-oral and respiratory contact.There are two types of vaccine, OPV （live attenuated virus） and IPV （inactivated polio virus）. Currently, there is a plan of vaccination until the age of 5 with OPV. The children vaccinated expel a virus （derived from the vaccine） to the environment, and some of the people that have oral contact with them, get vaccinated by the herd behavior. Nevertheless, taking into account the lately observed facts about the reversion to virulence of the oral polio vaccine during its circulation in the environment, a change in the current vaccination schedule is being contemplated, where the oral polio vaccine can be replaced by the inactivated vaccine. Nowadays, In Colombia the inactivated oral polio vaccine is recommended for children presenting immune deficiency who are vaccinated with IPV. These children do not expel poliovirus to the environment. This work presents a mathematical model that describes the dynamics of the infection in a population where the two types of vaccination are carried out. The population is divided into two groups of age and Michaelis-Menten interactions. Different strategies of vaccination are simulated and analyzed.