Wireless distributed test system based on transient pressure signal detection and recognition

During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology is proposed for transient pressure test system.In the process of signal acquisition,firstly,electrical levels are monitored in real time to find effective abrupt changes and mark them;then the effective data segments are detecdted totected;thus the effective signals can be acquired in turn finally.The experimental results show that the shock wave signal can be collected effectively and the reliability of the test system can be improved after removal of interferences.

Modeling and Analysis for Practical CT Based on Transient Test and Parameter Identification

In the transient process of power grid faults,the transferring distortion of current transformer(CT)can seriously affect relay protection performance.Under these conditions,it is difficult to analyze the ferromagnetic characteristic of the magnetizing branch in the transient equivalent circuit of CT.The Jiles-Atherton hysteresis model(J-A model),which is widely used in digital simulations,can accurately describe the hysteresis and saturation process of the core characteristics;however,to acquire the parameters of the J-A model of current transformers in practical use is still a challenging problem.In this paper,physical tests based on a practical CT and parameter identification are presented to solve the problem.The basic hysteresis loops of P,PR,and TPY class of practical current transformers are obtained through physical tests.Thus,the J-A model parameters are identified using a hybrid genetic/simulated annealing algorithm,based on which transient simulation models of different class CTs are constructed.The effectiveness of the proposed method is verified via dynamic physical simulation tests.A typical accident is analyzed based on these models.

Impact of Typical Steady-state Conditions and Transient Conditions on Flow Ripple and Its Test Accuracy for Axial Piston Pump

The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated working conditions. However, the pump usually has to work in large-scale and time-variant working conditions. Therefore, the flow ripple characteristics of pump and analysis for its test accuracy with respect to variant steady-state conditions and transient conditions in a wide range of operating parameters are focused in this paper. First, a simulation model has been constructed, which takes the kinematics of oil film within friction pairs into account for higher accuracy. Afterwards, a test bed which adopts Secondary Source Method is built to verify the model. The simulation and tests results show that the angular position of the piston, corresponding to the position where the peak flow ripple is produced, varies with the different pressure. The pulsating amplitude and pulsation rate of flow ripple increase with the rise of pressure and the variation rate of pressure. For the pump working at a constant speed, the flow pulsation rate decreases dramatically with the increasing speed when the speed is less than 27.78% of the maximum speed, subsequently presents a small decrease tendency with the speed further increasing. With the rise of the variation rate of speed, the pulsating amplitude and pulsation rate of flow ripple increase. As the swash plate angle augments, the pulsating amplitude of flow ripple increases, nevertheless the flow pulsation rate decreases. In contrast with the effect of the variation of pressure, the test accuracy of flow ripple is more sensitive to the variation of speed. It makes the test accuracy above 96.20% available for the pulsating amplitude of pressure deviating within a range of ~6% from the mean pressure. However, with a variation of speed deviating within a range of ±2% from the mean speed, the attainable test accuracy of flow ripple is above 93.07%. The model constructed in this research proposes a method to determine the flow ripple characteristics of pump and its attainable test accuracy under the large-scale and time-variant working conditions. Meanwhile, a discussion about the variation of flow ripple and its obtainable test accuracy with the conditions of the pump working in wide operating ranges is given as well.

Harnessing deep transient testing for reservoir characterization and CO_(2) emission reduction in challenging geological settings

This paper provides a comprehensive overview of Deep Transient Testing(DTT),a cutting-edge technique for reservoir characterization that has revolutionized the oil and gas industry.The main aim of DTT is to characterize the reservoir with a deeper radius of investigation.The optimization of the radius of investigation with the DTT approach is studied in detail.Reveal is a commercial numerical simulation application used to simulate the DTT process and evaluate the pressure wave analysis in the porous media.The main aim of the simulation is to understand the impact of the reservoir quality on the pressure response and use it to address the noise-to-pule ratio,which is a determinantal parameter in testing duration.The tested wells with the DTT tool show that measured well productivity can deliver the minimum commercial rate.The has been delivered within 2 days compared to the potential test time of 21 days which saved the 19 rig days and contributed to C02 emission reduction of(gas flaring 1340+rig emission 600)1940 Metric tons equivalent to 421 cars emission in a year.However,DTT also presents certain limitations,such as the requirement for specialized equipment and expertise,as well as the potential for formation damage during testing.This study provides a detailed description of the DTT technique,encompassing its history,theory,and practical applications.Furthermore,it discusses the benefits and limitations of DTT and presents case studies to illustrate its effectiveness across various reservoir types.Overall,this study serves as a valuable resource for reservoir engineers,geologists,and other professionals involved in the exploration and production of oil and gas.

A well test model for stress-sensitive and heterogeneous reservoirs with non-uniform thicknesses

In view of the anisotropy,heterogeneity and stress-sensitive permeability in low permeability reservoirs,an analytical well test model was established by introducing the concept of permeability modulus.This model considered the permeability stress-sensitivity,wellbore storage effect,and the skin effect.The perturbation technique and Laplace transformation were used to solve the mathematical model analytically in Laplace space,and the bottom-hole pressure type curves were plotted and analyzed in real space by using the Stehfest numerical inversion.

Executive function during transient ischemic attacks

BACKGROUND： Recent researches demonstrate that damage of executive function is an early manifestation of vascular cognitive disorder. OBJECTIVE： To investigate the executive functions of patients with transient ischemic attack （TIA）. DESIGN： Case control. SETTING： Department of Neurology, the First Affiliated Hospital of Xinxiang Medical College. PARTICIPANTS： A total of 83 TIA patients （46 males and 37 females, aged 32 - 74 years） were selected from Department of Neurology, the First Affiliated Hospital of Xinxiang Medical College from July 2005 to December 2006. The diagnosis of TIA was established by the criteria of cerebrovascular diseases made by the Fourth National Cerebrovascular Disease Meeting. In these cases, forty-five patients （54%） were involved in internal carotid artery, and thirty-eight patients （46%） were involved in vertebral basilar system. Fifty healthy adults （Control group： 28 males and 22 females, aged 32 - 74 years） were chosen from retiree in community and family of patients. All of them were right-handedness, without cerebrovascular disease, cerebral trauma, inborn oligophrenia, and heating and visual disorders; also they had no anxiety and depression nearly one week. In addition, all the subjects cooperated with examination. METHODS： After TIA diagnosis, all patients received neuropsychological examination, including attention and inhibition, working memory, flexibility, planning and diversion, based on Stroop tests （C and CW） and the Wisconsin card sorting tests （WCST）. ① WCST test： The edition revised by Nelson was used. We would take the times of sorting, incorrect response, persistent incorrect response, and randomly incorrect response as the index of evaluation.② Stroop tests： The edition revised by Trenarry was used and this test had two types： form color and form color-word. Their incorrect response and response time were recorded for data analysis in the end. MAIN OUTCOME MEASURES： Results of WCST test and Stroop tests. RESULTS： A total of 83 TIA patients and 50 healthy subjects were involved in the final analysis. Items of Stroop tests, including response time of Stroop-C test, incorrect response of Stroop-C test, response time of Stroop-CW test and incorrect response of Stroop-CW test, and items of WCST, including incorrect response, persistent incorrect response and random incorrect response, between internal carotid artery system and vertebral basilar artery system were （93.87±24.39） s, 3.16±3.97, （228.46±68.13） s, 12.91 ± 10.56, 55.42± 20.38, 26.58± 10.41, 28.62±11.22; （96.76±24.75） s, 3.89±4.77, （223.46±72.54） s, 18.71 ± 13.80, 52.47 ±22.25, 28.82± 16.20, 23.39±9.72, respectively; this was higher than those in the control group [（52.10± 12.18） s, 1.68± 1.97, （134.86±34.15） s, 4.22±4.21, 32.46± 17.97, 14.42±8.47, 18.24± 10.24, P 〈 0.05 - 0.01]. Times of sorting of WCST between internal carotid artery system and vertebral basilar artery system were obviously lower than those in the control group （8.27±2.73, 8.66±2.77, 11.22±2.41, P 〈 0.01）. However, there were no significant differences between internal carotid artery system and vertebral basilar artery system （P 〉 0.05）. CONCLUSION： Patients with TIA have executive dysfunctions, and the dysfunctions have no difference between internal carotid artery system and vertebral basilar artery system.

Estimation of pulsed laser-induced single event transient in a partially depleted silicon-on-insulator 0.18-μm MOSFET

In this paper, we investigate the single event transient （SET） occurring in partially depleted silicon-on-insulator （PDSOI） metal-oxide-semiconductor （MOS） devices irradiated by pulsed laser beams. Transient signal characteristics of a 0.18-p.m single MOS device, such as SET pulse width, pulse maximum, and collected charge, are measured and an- alyzed at wafer level. We analyze in detail the influences of supply voltage and pulse energy on the SET characteristics of the device under test （DUT）. The dependences of SET characteristics on drain-induced barrier lowering （DIBL） and the parasitic bipolar junction transistor （PBJT） are also discussed. These results provide a guide for radiation-hardened deep sub-micrometer PDSOI technology for space electronics applications.

Transient simulation of a pump-turbine with misaligned guide vanes during turbine model start-up

Experimental studies of a model pump-turbine S-curve characteristics and its improvement by misaligned guide vanes （MGV） were extended to prototype pump turbine through 3-D transient flow simulations. The unsteady Reynolds-averaged Navier-Stokes equations with the SST turbulence model were used to model the transient flow within the entire flow passage of a reversible pump-turbine with and without misaligned guide vanes during turbine model start-up. The unstable S-curve and its improvement by using misaligned guide vane were verified by model test and simulation. The transient flow calculations were used to clarify the variations of pressure pulse and internal flow behavior in the entire flow passage. The use of misaligned guide vanes can eliminate the S-curve characteristics of a pump-turbine, and can significantly increase the pressure pulse amplitude in the entire flow passage and the runner radial forces during start-up. The MGV only decreased the pulse amplitude on the guide vane suction side when the rotating speed was less than 50% rated speed. The hydraulic reason is that the MGV dramatically changed the flow patterns inside the entire flow passage, and destroyed the symmetry of the flow distribution inside the guide vane and runner.

Page Test应用于瞬态变化检测时的性能计算

Page Test是针对变化检测的一种常用方法。一般来说,我们用平均运行时间长度来描述Page Test方法的性能,这对稳态变化检测来说是合理的,但对于瞬态变化检测而言则显得不够完善;针对此种不足,提出了一种基于快速傅立叶变换的FFT法,它可以以很高的精度计算Page Test检测瞬态变化时的虚警和检测概率。最后通过数值仿真表明,FFT法能很好地描述Page Test方法的性能。

Processing and analysis of transient pressure measurements from permanent down-hole gauges

With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of research interests in further developing pressure transient processing and analysis techniques. Transient pressure measurements from PDG are characterized by long term and high volume data. These data are recorded under unconstrained circumstances, so effects due to noise, rate fluctuation and interference from other wells cannot be avoided. These effects make the measured pressure trends decline or rise and then obscure or distort the actual flow behavior, which makes subsequent analysis difficult. In this paper, the problems encountered in analysis of PDG transient pressure are investigated. A newly developed workflow for processing and analyzing PDG transient pressure data is proposed. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that this new technique works well and the potential for practical application looks very promising.

正弦扫描振动模拟瞬态振动环境等效性研究

使用正弦扫描振动模拟低频瞬态振动环境是航天工业的一种传统试验方法,其对产品的环境考核可能同时存在欠试验和过试验。首先对两者等效性进行分析,进而采用冲击响应谱、最大响应谱等相关理论,对等效正弦扫描振动试验条件制定中的扫描速率、阻尼系数进行了研究,并给出参数选择建议。最终提出了制定正弦扫描振动环境试验条件的步骤,为采用正弦扫描试验进行低频瞬态环境适应性考核提供借鉴。

不稳定试井技术研究进展及发展趋势

为更好监测油气藏生产动态,提升油气田试井产能,梳理了4种常用不稳定试井技术的原理、解释方法及应用效果,分析了不稳定试井技术存在的问题,并提出了未来的重点攻关方向。结果表明:目前常用的不稳定试井技术主要存在井间干扰现象严重、试井曲线特征复杂、试井解释准确率低且复杂断块油藏常规试井效率低和损耗大等问题;数值试井、垂向干扰试井及低频脉冲试井等新型试井技术可解决常规不稳定试井技术存在的问题;不稳定试井技术下步发展趋势是深层超深层测试工艺、低渗致密储层测试资料评价、压裂效果评价及资料的综合应用等方面,可着重于数值试井、多分层试井等方面的技术攻关。通过对不稳定试井技术的综合剖析,可对现场测试提供技术参考,并为后续技术发展提供新视角。

Characteristic Analysis of Transient Electromagnetic Disturbance Data in Substation

Characteristic analysis of transient electromagnetic disturbance data is very important. In this paper, the time-domain and frequency-domain characteristics of transient electromagnetic disturbance caused by switching operations in substations are analyzed. Two methods are adopted in time-domain analysis. One method is histogram and the other one is normality test. An appropriate procedure for the normality test is proposed. Furthermore, the method used in frequency- domain analysis is to obtain overall envelope. These statistical characteristic analysis methods are showed to be of great value in analyses of the measured samples. The simulation results showed that these methods are effective.

Transient elastography: A non-invasive tool for assessing liver fibrosis in HIV/HCV patients

AIM: To assess the prevalence of advanced liver fibrosis (ALF) in human immunodeficiency virus (HIV), hepatitis C virus (HCV) and HIV/HCV patients using transient elastography, and to identify factors associated with ALF. METHODS: Between September 2008 and October 2009, 71 HIV mono-infected, 57 HIV/HCV co-infected and 53 HCV mono-infected patients on regular follow-up at our Center were enrolled in this study. Alcohol intake, the main parameters of liver function, presence of HCV-RNA, HIV-RNA, duration of highly active anti-retroviraltherapy (HAART) and CD4 cell count were recorded. ALF was defined as liver stiffness (LS) ≥ 9.5 kPa. To estimate liver fibrosis (LF) a further 2 reliable biochemical scores, aspartate aminotransferase platelet ratio index (APRI) and FIB-4, were also used. RESULTS: LS values of co-infected patients were higher than in either HIV or HCV mono-infected patients (χ 2M H = 4, P < 0.04). In fact, LS ≥ 9.5 was significantly higher in co-infected than in HIV and HCV mono-infected pa-tients (χ 2 = 5, P < 0.03). Also APRI and the FIB-4 index showed more LF in co-infected than in HIV mono-infect-ed patients (P < 0.0001), but not in HCV mono-infected patients. In HIV?HCV co-infected patients, the extent of LS was significantly associated with alcohol intake (P < 0.04) and lower CD4+ cell count (P < 0.02). In HCV pa-tients, LS was correlated with alcohol intake (P < 0.001) and cholesterol levels (P < 0.03). Body mass index, dia-betes, HCV-and HIV-viremia were not significantly cor-related with LS. In addition, 20% of co-infected patients had virologically unsuccessful HAART; in 50% compliance was low, CD4+ levels were < 400 cells/mm 3 and LS was > 9.5 kPa. There was no significant correlation between extent of LF and HAART exposure or duration of HAART exposure, in particular with specific dideoxynucleoside analogues. CONCLUSION: ALF was more frequent in co-infected than mono-infected patients. This result correlated with lower CD4 levels. Protective immunological effects of HAART on LF progression outweigh its hepatotoxic effects.

导叶叶片数对喷水推进泵瞬态特性的影响

为揭示喷水推进泵不同导叶叶片数时的瞬态特性规律,基于DES混合模拟和FEM声学有限元方法,对喷水推进泵流场和声场进行数值模拟,并进行试验,验证了瞬态特性数值计算方法的准确性,研究了不同导叶叶片数(Z=5,6,7)对喷水推进泵推力、压力脉动、内流诱导噪声等性能的影响规律.结果表明:随着导叶叶片数增大,喷水推进泵推力先减小后增大,流量逐渐减小,转矩逐渐增大;导叶叶片数对叶轮出口压力脉动分布规律影响较小,对压力脉动主频处幅值有较大影响,轮毂处压力脉动幅值受导叶叶片数增大先减小后增大,轮缘和流道中心处幅值随着导叶叶片数增大逐渐减小;导叶叶片数变化会改变内流诱导噪声主频,增大导叶叶片数有利于降低喷水推进泵内流诱导噪声主频处幅值和总声压级.

短路电流对二次设备电磁干扰分析及抗干扰措施

目前智能配电网的建设不断推进,加快了配电开关一二次设备相关技术的发展,也对长期处于复杂电磁环境下的二次设备提出了更高的要求。文中基于合成试验回路搭建了短路电流对配电开关二次设备电磁干扰试验平台,开展开断故障电流对相关干扰对成套设备的影响研究,分析干扰信号产生原因、频谱特性。针对干扰的特性设计一套抗干扰测量系统,利用ATP-EMTP模拟合成回路进行仿真分析并进行实际测试验证。结果表明:成套设备进行开断试验时,二次设备端口会受到较大的干扰。电流波形也会发生畸变,干扰电流的最高可到26 A,且干扰电流受电流互感器磁饱和和退饱和的影响,通过增加抗干扰措施,二次设备输出准确度与之相比提升约40%。本次的试验结果可为一二次融合成套设备中二次设备电磁兼容研究提供相关依据。

制动荷载作用下道岔区采用不同垫板的扣件适应性研究

通过试验对比扣件分别采用聚脂垫板和橡胶垫板时的纵向力学性能,基于瞬态动力分析获得制动力作用下道岔区间扣件分别采用这2种垫板时钢轨的纵向位移与受力动力响应,分析坡度对其产生的影响。研究结果表明:当列车在岔区制动且相连车辆的2个相邻转向架同时作用在尖轨上时,钢轨的最大位移和受力分别产生于尖轨尖端和跟端处;获得了道岔直、侧股线路上的最不利制动位置;钢轨纵向位移和受力随着坡度增大而呈线性增大;相较于聚酯垫板,当扣件采用橡胶垫板时,初始滑移位移和最大纵向阻力较大,而弹性阶段扣件纵向阻力-位移曲线斜率较小;各坡度下钢轨最大位移较大,最大受力较小,且受力减小幅度大于位移增大幅度,采用橡胶垫板较有利;在列车停车瞬间,钢轨纵向位移和受力突然增大,随后振幅衰减,采用橡胶垫板时振动频率和振幅比采用聚酯垫板时的稍大。

古兜山隧道富水段探测与处置技术研究

为探明古兜山隧道富水情况,通过超前钻孔、瞬变电磁法探测隧道富水段情况;针对古兜山隧道的富水情况,开展现场注浆止水加固试验研究,提出富水区注浆止水关键技术;综合考虑隧道地下水排放量与植被生态的平衡,给出隧址区的地下水允许排放量。研究结果表明:选择普通水泥-水玻璃双液浆用于钻孔揭露隧道涌水量较大的区域,确保注浆效果;综合考虑地下水压力、地层岩性、浆液的性质和浓度及注浆扩散半径等因素,确定注浆终压取值为5~6 MPa;针对植被、生态环保要求,按2年内恢复原始地下水位,确定泄洪口区、水库连接区及隧道近出口区的地下水允许排放量。

基于LSTM的半航空瞬变电磁资料去噪方法研究

随着干扰电磁环境的因素越来越多,半航空瞬变电磁数据所含噪声的特性难以正确地处理和分析,而去噪是提高瞬变电磁场信号处理和分析精度的重要手段之一。相较于传统的去噪方法大都依赖频率特征、耗时较长以及计算参数难以确定,LSTM(Long Short-Term Memory)神经网络不依赖频率特征的同时能够很好地处理非线性时间序列。因此笔者将LSTM应用于半航空瞬变电磁数据处理,在一维正演数据添加各类噪声的基础上,分为训练和测试,训练采用监督学习方式进行,从而捕获信号的特征和结构信息,测试阶段也采用监督学习方式进行,利用有标签训练数据对网络进行优化进一步提高去噪效果。最后将测试效果良好的模型应用于实际资料中,结果表明此方法能够有效地去除晚期道中的噪声,是一种能够用于半航空瞬变电磁数据去噪的可行手段。

基于灵敏度分析的齿轮齿条动态力学研究

针对齿轮齿条在长期承受交变载荷下易产生疲劳失效的问题,提出了瞬态动力学和灵敏度相结合的动态力学评估的方法。通过ANSYS建立齿轮齿条瞬态动力学模型,选取最大运行工况进行分析。通过DOE试验获取样本数据,并采用多元二次回归拟合样本数据的响应面模型,分析了各输入参数对各性能指标的灵敏度。研究结果表明:输入转矩对齿轮齿条动态啮合的影响最明显,摩擦系数次之,负载的影响最小,可为齿轮齿条传动优化提供理论参考。