Design and Test of Closed Hydraulic Transmission System of 4WD High-clearance Wheeled Sprayer

In conjunction with the working characteristics of the high-clearance wheeled sprayer and the benefits of the closed hydraulic system,a series of reasonable working parameters should be established,and a hydraulic system that fulfills the requisite specifications should be designed.The AMESim software model is employed to construct a closed hydraulic transmission system,and the simulation analysis is then performed according to the data of hydraulic components.According to analysis results,the prototype can be optimized and upgraded,and a verification test is further carried out.The test results demonstrate that the designed closed hydraulic transmission system meets the actual working requirements of the high-clearance wheeled sprayer and provides a stable experimental platform for intelligent control of agricultural machinery.

Comparative analysis of the effects of gunpowder and plasma ignition in closed vessel tests

This paper presents the results of a comparative investigation into the effects of the ignition method on the ballistic properties of a single-base gun propellant,as determined via closed vessel tests.Conventional gunpowder ignition and plasma jet ignition methods were used,and differences in the ignition time were analysed.The influence of the ignition method on the dynamic vivacity is discussed.It is shown that this influence is significant in the first phase of the combustion process,and with respect to the low values of the loading density.In the second phase of the combustion process,and for large values of the loading density,the dynamic vivacity plots for the two ignition methods converge.Regarding the burning law,close values of the exponent were obtained for the two ignition methods.The dynamic vivacity plots determined for plasma ignition reveal stronger dependence on the loading density than those determined for gunpowder ignition.The conclusion is that plasma ignition is not a solution to the problems inherent to the process of determining the ballistic properties of propellants,which results in deviation of the burning process from the geometric burning law.

Pressure Buildup Analysis for a Well in a Closed, Bounded Multiwell Reservoir

A general method has been developed for analyzing pressure buildup data from a well located in a system with both production and injection wells in a closed, bounded two-phase flow reservoir. The proposed method enables one to calculate the total mobility or permeability-thickness product, the skin factor, the average drainage-area pressure and the injection-production ratio （at the instant of shut-in） with accuracy from pressure buildup （or falloff） data dominated by a linear trend of reservoir pressure. Out of thousands of well tests, several typical field examples have been presented to illustrate the application of the proposed method for analyzing pressure transient data from a well located in a water-injection multiwell reservoir. And the possible application of this method to heterogeneous systems such as naturally fractured reservoirs is also discussed. Approaches to aid practicing engineers in verifying the buildup interpretation （or recognizing the interference of offset wells） are presented. Extension of the presented method to a gas well located in a multiwell gas reservoir is also suggested

Use of A Shatter Test Vessel to Assess Propellant Safety

At low temperatures,gun propellant grains may become brittle and this can lead to fracture or shatter of the grains during gun firing.Should this event occur then it will result in an increase in the burning surface of the propellant and will give rise to a change in ballistic performance.Also,if the resultant over pressure is sufficient,a breech failure may result.Understanding the propensity of a grain to fracture or shatter is therefore important in determining its safety in use.This document describes a test that may be used to derive knowledge and to quantify the physical behaviour of a gun propellant grain at the low temperatures at which fracture or shatter is most likely to occur.

Modelling Design and Test of Steam Centrifugal Compressor

This paper discusses the modeling design and accuracy analysis of a single stage steam centrifugal compressor for China′S first seawater desalinization plant, and gives a brief presentation on the closed loop vapour test platform designed and constructed for qualification of the compress or for performance and operational reliability, and results of tests run with the compressor. Both tests and actual operation show the modeling design is successful, and the compressor achieved and exceeded what was expected in performance. The seawater desalinization plant has run with excellent performance and reliability for several years for the national seawater desalinization demonstration program. This proves it is practical and practicable to develop and design China′s steam centrifugal compressors in series from air centrifugal compressors by maintaining equal specific volume ratio at both inlet and outlet of the compressor.

Effects of subject’s wakefulness state and health status on approximated entropy during eye opening and closure test of routine EEG examination

This study tested a novel method designed to provide useful information for medical diagnosis and treatment. We measured electroencephalography (EEG) during a test of eye opening and closing, a common test in routine EEG examination. This test is mainly used for measuring the degree of alpha blocking and sensitivity during eyes opening and closing. However, because these factors depend on the subject’s awareness, drowsiness can interfere with accurate diagnosis. We sought to determine the optimal EEG frequency band and optimal brain region for distinguishing healthy individuals from patients suffering from several neurophysiological diseases (including dementia, cerebrovascular disorder, schizophrenia, alcoholism, and epilepsy) while fully awake, and while in an early drowsy state. We tested four groups of subjects (awake healthy subjects, drowsy healthy subjects, awake patients and drowsy patients). The complexity of EEG band frequencies over five lobes in the human brain was analyzed using wavelet-based approximate entropy (ApEn). Two-way analysis of variance tested the effects of the two factors of interest (subjects’ health state, and subjects’ wakefulness state) on five different lobes of the brain during eyes opening and closing. The complexity of the theta and delta bands over frontal and central regions, respectively, was significantly greater in the healthy state during eyes opening. In contrast, patients exhibited increased complexity of gamma band activity over the temporal region only, during eyes-close. The early drowsy state and wakefulness state increased the complexity of theta band activity over the temporal region only during eyes-close and eyes-open states respectively, and this change was significantly greater in control subjects compared with patients. We propose that this method may be useful in routine EEG examination, to aid medical doctors and clinicians in distinguishing healthy individuals from patients, regardless of whether the subject is fully awake or in the early stages of drowsiness.

Establishment of Unstable Flow Model and Well Testing Analysis for Viscoelastic Polymer Flooding

At present, the polymer solution is usually assumed to be Newtonian fluid or pseudoplastic fluid, and its elasticity is not considered on the study of polymer flooding well testing model. A large number of experiments have shown that polymer solutions have viscoelasticity, and disregarding the elasticity will cause certain errors in the analysis of polymer solution seepage law. Based on the percolation theory, this paper describes the polymer flooding mechanism from the two aspects of viscous effect and elastic effect, the mathematical model of oil water two-phase three components unsteady flow in viscoelastic polymer flooding was established, and solved by finite difference method, and the well-test curve was drawn to analyze the rule of well test curve in polymer flooding. The results show that, the degree of upward warping in the radial flow section of the pressure recovery curve when considering polymer elasticity is greater than the curve which not considering polymer elasticity. The relaxation time, power-law index, polymer injection concentration mainly affect the radial flow stage of the well testing curve. The relaxation time, power-law index, polymer injection concentration and other polymer flooding parameters mainly affect the radial flow stage of the well testing curve. The larger the polymer flooding parameters, the greater the degree of upwarping of the radial flow derivative curve. This model has important reference significance for well-testing research in polymer flooding oilfields.

Mathematical Modeling of Shear Stress and Direct Shear Test for Compressible Soil: Case of Soil Bordering the Wouri River

This paper focuses on the development of the mathematical model of shear stress by direct shear test for compressible soil of the littoral region, which will be a great tool in the hand of geotechnical engineers. The most common use of a shear test is to determine the shear strength which is the maximum shear stress that a material can withstand before the failure occurs. This parameter is useful in many engineering designs such as foundations, roads and retaining walls. We carried out an experimental laboratory test of ten samples of undisturbed soil taken at different points of the border of Wouri river of Cameroon. The samples were collected at different depths and a direct shear test was conducted. The investigations have been performed under constant vertical stresses and constant sample volume with the aim to determine the frictional angle and the cohesion of the compressible soil which are so important to establish the conditions of buildings stability. Special care was taken to derive loading conditions actually existing in the ground and to duplicate them in the laboratory. Given that the buildings constructed in this area are subjected to settlement, landslide, and punch break or shear failure, the cohesion and the frictional angle are determined through the rupture line after assessed the mean values of the shear stress for the considered ten samples. The bearing capacity of the soil, which is the fundamental soil parameter, was calculated. From the laboratory experimental results, the least squared method was used to derive an approximated mathematical model of the shearing stress. Many optimizations methods were then considered to reach the best adjustment.

Recursive Algorithm and Alternate Operation Strategy in Sequential Tests

Based on the sequential probability ratio test(SPRT)developed by Wald,an improved method for successful probability test of missile flight is proposed.A recursive algorithm and its program in Matlab are designed to calculate the real risk level of the sequential test decision and the average number of samples under various test conditions.A concept,that is "rejecting as soon as possible",is put forward and an alternate operation strategy is conducted.The simulation results show that it can reduce the test expenses.

Closed-Loop System Identification Approach of the Inertial Models

The mathematical model that approximates the dynamics of the industrial process is essential for the efficient synthesis of control algorithms in industrial applications. The model of the process can be obtained according to the identification procedures in the open-loop, or in the closed-loop. In the open-loop, the identification methods are well known and offer good process approximation, which is not valid for the closed-loop identification, when the system provides the feedback output and doesn’t permit it to be identified in the open-loop. This paper offers an approach for experimental identification in the closed-loop, which supposes the approximation of the process with inertial models, with or without time delay and astatism. The coefficients are calculated based on the values of the critical transfer coefficient and period of the underdamped response of the closed-loop system with P controller, when system achieves the limit of stability. Finally, the closed-loop identification was verified by the computer simulation and the obtained results demonstrated, that the identification procedure in the closed-loop offers good results in process of estimation of the model of the process.

A Hybrid Simulation Test Platform for Verifying the Protection Settings of SPS

To verify the effectiveness and correctness of the protection settings in ring structure Shipboard Power System (SPS), a digital-physical hybrid simulation platform at China Ship Development and Design Center (CSDDC) has been built, which aims to give double verification effect of design scheme and physical device. The platform consists of eMEGAsim digital simulator, signal power amplifiers and digital-analog interface equipments. With this platform, the multiple protection device of ring structure grid can be accessed to form a close-loop test system. Since eMEGAsim model-simulated faults and actual protection device actions are on real time, the tripping settings of each device as well as their coordinate performance between multiple devices can be verified in this close-loop test.

现代数理统计中假设检验的教学探讨

假设检验是现代概率论与数理统计教学中的重要内容和知识点,而假设检验包含建立原假设、构造统计量、计算概率分布、确定临界值和得出结论等过程。在教学过程中,很多教师都忽视建立原假设这个方面。由于没有强调原假设设计方法,学生碰到此类问题很容易产生疑惑出错。实际上,原假设的三个选择是不可以随意互换的,需要通过阅读问题,依据“小概率事件原理”来选择合适的假设。通过对假设检验中单边检验真题案例的教学探讨和分析,完成对原假设存在的三个选择的不同分析,然后对得到的结果进行比较。分析探讨在假设检验教学中做原假设和备择假设设计时,需要结合题目要求,按照“小概率事件原理”来设计假设的方案,促进学生对此问题的理解,并且在实际教学应用中取得良好的效果。

Fault Waveform Regenerator and Its Digital Closed-Loop Modification Technique

In order to provide a novel and more effective alternative to the commonly used relay protection testing device that outputs only the sinusoidal testing signals, the concept of fault waveform regenerator is proposed in this paper, together with its hardware structure and software flow chart. Fault waveform regenerator mainly depends on its power amplifiers (PAs) to regenerate the fault waveforms recorded by digital fault recorder (DFR). To counteract the PA’s inherent nonlinear distortions, a digital closed-loop modification technique that is different from the predistortion technique is conceived. And the experimental results verify the effectiveness of the fault waveform regenerator based on the digital closed-loop modification technique.

响应面结合模糊数学感官评价法优化油橄榄果渣曲奇饼干的配方及其品质测定

【目的】开发油橄榄果渣曲奇饼干。【方法】以低筋面粉、黄油和鲜鸡蛋为材料复配陇南油橄榄果渣、麦芽糖醇、金耳和纹党多糖,添加碳酸氢钠和氯化钠等食品添加剂研制油橄榄果渣低糖复合曲奇饼干,采用响应面结合模糊数学感官评价法优化了配方,对其抗氧化性、理化指标和微生物指标进行了检验。【结果】油橄榄果渣添加量为15%、麦芽糖醇添加量为30%、金耳添加量为10%和纹党多糖添加量为0.35%,曲奇饼干形态完整,断面结构细密、无粉末,硬度适中,薄厚均匀、口感细腻、咀嚼性好,酥脆、无颗粒感,油橄榄风味突出,气味协调、颜色均一卫生指标符合国家标准,具有很好的营养价值和抗氧化功能。【结论】为油橄榄果渣的进一步利用提供了参考。

均质黏性土中静压沉桩桩土界面孔压增量及有效土压室内试验研究

研究饱和黏性土中静压沉桩引起的桩土界面孔压增量及有效径向应力的变化规律对工程实践具有重要意义。利用自制的大比例模型试验系统,通过双壁开口和闭口管桩,实现了开口和闭口桩桩身表面嵌入式安装微型测试元件,得到了考虑孔压增量的桩土界面有效径向应力的变化规律。研究结果表明:入土深度越大,桩土界面孔压增量及有效径向应力越大,闭口桩桩土界面超孔压大于开口桩;桩身上部桩土界面超孔压和有效径向应力小于桩身下部;同一入土深度,随着桩身h/L的增加,桩土界面土压力存在侧压力“退化”的现象;特定试验条件下,闭口和开口桩桩土界面超孔压与上覆有效土体自重比值最大值分别是61.2%和52.1%,桩土界面有效径向应力是超孔压的3.76~5.46倍。桩土界面超孔压和有效径向应力与桩身h/L位置有关。

半封闭温室关键系统设计与应用

半封闭温室是近年来新兴温室,其中温室气候走廊和正压送风系统是半封闭温室的关键系统设计。通过对半封闭温室内夏季温度分布的均匀性和风道风速测试试验,验证温室的降温能力和送风系统性能。试验结果表明,SFG5-4型风机配套35 m长风道,送风相对均匀,风速4.3~4.7 m/s;对于温度分布规律来说,在同一水平方向上温室内各点的平均温差1.0~1.8℃,在同一高度方向上温室内各点的平均温差2.2~3.5℃,并且3.5 m湿帘比2.0 m湿帘降温效果好。

感知系统触发条件穿透率评估方法研究

预期功能安全问题制约着自动驾驶汽车的落地。自动驾驶感知系统面临的各种极端行驶环境等极易引起预期功能安全问题。因此,须按照现有预期功能安全标准,在安全分析阶段识别并评估种类多且数量大的触发条件,筛选高价值触发条件为后续测试验证提供测试场景输入。本文中首先基于对触发条件在自动驾驶系统中的风险演化过程的分析,提出一套包括暴露率、穿透率和危害率的三维感知系统触发条件评估体系。随后,基于层次分析法构建了触发条件穿透率量化评估方法。最后,针对某量产车型的融合感知系统分析并选取15个触发条件,构建测试用例并开展封闭场地测试,评估上述触发条件的穿透率。最终经计算筛选得到3个高风险触发条件,验证了触发条件穿透率量化评估方法的可行性。

基于模糊数学感官评价法优化牛肉风味植物肉配方

以大豆拉丝蛋白为主要原料,谷朊粉、豌豆蛋白、食用油、魔芋胶、TG酶为辅料研制一种中式麻辣牛肉风味植物肉休闲食品。先采用单因素试验探究谷朊粉、食用油、魔芋胶、TG酶添加量对植物肉感官品质的影响,再选取影响较大的3个因素进行响应面优化试验,通过模糊数学感官评价法进行分析。结果表明,以大豆拉丝蛋白湿基为基准,谷朊粉添加量4.21%、魔芋胶添加量0.63%、TG酶添加量0.56%、食用油3.00%时制品的感官品质最好。

变电站站控系统改造镜像闭环测试技术研究

针对变电站站控系统改造停电难、停电调试验收时间短、人工验收慢且信息核对不全面等问题,设计了一种变电站站控系统改造镜像闭环测试系统。针对现场运行设备搭建镜像系统,采用横向镜像比对、纵向闭环验证的机制,以功能模块化的思路完成变电站站控系统改造的自动测试,并自动生成标准化的测试结果报告。将现场人工验证环节提前移到所设计的镜像闭环测试系统中高效进行,可有效缩短现场停电时间,提前消除验证隐患,提高变电站的改造效率和质量。

稠油电加热嵌入式控制装置设计及其试验

为提高稠油井电加热系统的加热效率,解决油田中频电源加热运行控制主要依靠人工经验设置和低效的自动控制造成电能浪费的现状,本文设计了稠油电加热嵌入式控制装置。基于非嵌入式获取的油井生产电信号,以稠油开采电机的电功率为闭环反馈信号,获取油液最优温度的参考输入。在此基础之上,通过井口油液温度的微分反馈环节,改善温度迟滞效应,实现中频电源的节能优化控制。通过对嵌入式硬件核心电路模块的设计和主要软件功能的开发,不仅实现了稠油井电加热过程的动态控制,还实现了各项运行指标的现场及云端的实时监测。稠油井场试验分析表明,所设计的稠油电加热嵌入式控制装置符合井场节能安全的生产需求,节约能耗可达20%。