Stability and melting behavior of boron phosphide under high pressure

Boron phosphide(BP)has gained significant research attention due to its unique photoelectric and mechanical properties.In this work,we investigated the stability of BP under high pressure using x-ray diffraction and scanning electron microscope.The phase diagram of BP was explored in both B-rich and P-rich environments,revealing crucial insight into its behavior at 5.0 GPa.Additionally,we measured the melting curve of BP from 8.0 GPa to 15.0 GPa.Our findings indicate that the stability of BP under high pressure is improved within B-rich and P-rich environments.Furthermore,we report a remarkable observation of melting curve frustration at 10.0 GPa.This study will enhance our understanding of stability of BP under high pressure,shedding light on its potential application in semiconductor,thermal,and light-transmitting devices.

A new method to construct reservoir capillary pressure curves using NMR log data and its application

By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed to evaluate reservoir pore structure in the intervals with NMR log data. An in-situ example of evaluating reservoir pore structure using the capillary pressure curves by this new method is presented. The result shows that it accurately detects the change in reservoir pore structure as a function of depth.

Effects of sample dimensions and shapes on measuring soil-water characteristic curves using pressure plate

It is well known that soilewater characteristic curve （SWCC） plays an important role in unsaturated soil mechanics, but the measurement of SWCC is inconvenient. In laboratory it requires days of testing time. For fine-grained clays, it may last for a couple of months using pressure plate tests. In this study, the effects of sample dimensions and shapes on the balance time of measuring SWCCs using pressure plate tests and the shape of SWCCs are investigated. It can be found that the sample dimensions and shapes have apparent influence on the balance time. The testing durations for circular samples with smaller diameters and annular samples with larger contact area are significantly shortened. However, there is little effect of sample dimensions and shapes on the shape of SWCCs. Its mechanism is explored and discussed in details through analysing the principle of pressure plate tests and microstructure of the sample. Based on the above findings, it is found that the circular samples with smaller dimensions can accelerate the testing duration of SWCC using the pressure plate.

Fusion curves and thermodynamic properties of carbon tetrachloride,chloroform,bromoform and silicon tetrachloride at pressure up to 3500 MPa

The fusion temperature as a function of pressure for carbon tetrachloride, chloroform, bromoform and silicon tetrachloride at pressures up to 3500MPa has been determined. The experimental data were fitted by the equation Tfus=T0（1 ＋ Δp/a1）^a2 exp（-a3Δp） and the changes of the maolar enthalpy and molar internal energy on fusion were calculated using the parameters of the fitted equation. Comparisons with the data from the literature show that the experimental data, parameters of fitted equations, changes of the molar enthalpy and molar internal energy are reliable.

Pressure Buildup Analysis Using Type Curves for a Well in a Pressure-Maintained System

The development and application of a new solution is demonstrated for the type-curve analysis and in-terpretation of well test data from a multiwell reservoir system of both production and injection wells with two-phase flow. The buildup type curves or buildup behavior could be obtained through the solution by using su-perposition. But a new outer boundary condition for variable pressure boundary must be introduced to obtain the correct pressure buildup solutions by superposition. A technique is shown to determine the deviation time from the infinite-acting semilog radial flow stabilization in the derivatives of pressure, which is calculated with respect to and plotted vs. shut-in time. Field examples are given to illustrate the use of the proposed method for analyzing transient pressure data from a well located in a multi-well water-injection reservoir. An adaptive genetic algorithm-based method is used to match the pressure and pressure derivative data to estimate reservoir parameters. The validity and applicability of the proposed method are also demonstrated through the examples.

Biomagnetic Validation to Skin Level for Blood Pressure Curves and Venous

An analysis of the reproducibility from signal record bioelectric heart activity is presented. The measurements were carried out with a recently patented medical device, which one is able to record the curves of pressure arterial and venous as those obtained using the gold standard technique in these evaluations, the cardiac catheterization technique. The measurements were carried out 15 health subjects and patients;each one was measured 5 times in order to have auto-correlations and correlations of these records. Analysis indicates correlations from 0.9 to 1 as long as p values were below 0.05. It is indicated an excellent reproducibility of evaluated patients.

Determination of volumetric elastic moduli of plant leaf cells based on pressure-volume curves

Volumetric elastic modulus （VEM） is an important parameter in biophysics and biomechanics of plants for in particular understanding cell growth. This paper proposes a new relation that can be used for precisely determining VEM. With the aid of this relation, it shows that the exponential approximation of the pressure-volume relationship adopted in most of the literatures in this field may lead to serious errors on VEM.

Pump-stopping pressure drop model considering transient leak-off of fracture network

By introducing the coupling flow expressions of main fracture-matrix, secondary fracture-matrix and main fracture-secondary fracture into the traditional main fracture material balance equation, the “main fracture-secondary fracture-matrix” leak-off coupling flow model is established. The pressure-dependent fracture width equation and the wellbore injection volume equation are coupled to solve the pressure-rate continuity problem. The simulation and calculation of the bottomhole pressure drop and fracture network closure after the pump stopping in slickwater volumetric fracturing treatment are realized. The research results show that the log-log curve of pump-stopping bottomhole pressure drop derivative presents five characteristic slope segments, reflecting four dominant stages, i.e. inter-fracture crossflow, fracture network leak-off, fracture network closure and residual leak-off, after pump shutdown. At the initial time of pump shutdown for volumetric fracturing treatment of horizontal well, the crossflow between main and secondary fractures is obvious, and then the leak-off becomes dominant. The leak-off of main and secondary fractures shows a non-uniform decreasing trend. Specifically, the leak-off of main fractures is slow, while that of secondary fractures is fast;the fracture network as a whole presents the leak-off law of fast first, then slow, until close to zero. The influence of fracture network conductivity on the shape of pressure decline curve is relatively weaker than that of fracture network size. The fracture network conductivity is positively correlated with leak-off volume and fracture closure. The secondary fracture size is positively correlated with leakoff volume and closure of the secondary fracture, but negatively correlated with closure of the main fracture. Field data validation proves that the proposed model and simulation results can effectively reflect the closure characteristics of the fracture network, and the interpretation results are reliable and can reflect the non-uniform stimulation performance of each fracturing stage of an actual horizontal well.

Characterization of reservoir properties and pore structure based on micro-resistivity imaging logging: Porosity spectrum, permeability spectrum, and equivalent capillary pressure curve

According to the capillary theory,an equivalent capillary model of micro-resistivity imaging logging was built.On this basis,the theoretical models of porosity spectrum(Ф_(i)),permeability spectrum(K_(i))and equivalent capillary pressure curve(pe)were established to reflect the reservoir heterogeneity.To promote the application of the theoretical models,the Archie's equation was introduced to establish a general model for quantitatively characterizing bi,K,and pei.Compared with the existing models,it is shown that:(1)the existing porosity spectrum model is the same as the general equation of gi;(2)the Ki model can display the permeability spectrum as compared with Purcell's permeability model;(3)the per model is constructed on a theoretical basis and avoids the limitations of existing models that are built only based on the component of porosity spectrum,as compared with the empirical model of capillary pressure curve.The application in the Permian Maokou Formation of Well TsX in the Central Sichuan paleo-uplift shows that the Ф_(i),K_(i),and p_(ci) models can be effectively applied to the identification of reservoir types,calculation of reservoir properties and pore structure parameters,and evaluation of reservoir heterogeneity.

基于MPGW分布的压力蒸汽灭菌器可靠性分析

浴缸形状的失效率函数因其能够捕捉某些实际情境中的故障率特征,在机械结构可靠性分析中至关重要。引入一种修正广义幂威布尔(Modified Power Generalized Weibull,MPGW)分布,能够建模表征浴缸形状的失效率变化规律。为评估该模型的有效性,本研究使用了压力蒸汽灭菌器故障数据集进行实证研究,并将其性能与5种经典分布模型进行了比较,发现该模型在灵活性上具有较大优势。

沿空留巷密集钻孔切顶机理及关键参数确定方法

为实现密集钻孔切顶条件下沿空留巷顶板结构安全稳定,研究正常情况与密集钻孔条件下顶板岩层结构受力状况,基于岩石断裂理论和弹性理论分析回采前后顶板密集钻孔孔间围岩受力分布及其破断过程,明确密集钻孔切顶机理及相邻钻孔的孔间集中应力相互作用机制,推导工作面端头弧形三角板结构巷道侧边界密集钻孔孔间围岩的拉剪应力计算公式。在此基础上,分析不同参数对孔间围岩所受拉剪应力的影响作用,提出沿空留巷密集钻孔切顶关键参数确定方法。研究表明:密集钻孔主要通过回采前后钻孔周围应力条件改变来增加钻孔围岩拉剪应力集中程度,引起孔间裂隙扩张联通,形成切缝线破断关键岩层。回采前钻孔主要受水平挤压应力影响,回采后钻孔受力逐渐转变为采空区顶板回转下沉产生的拉剪应力为主,钻孔孔间围岩状态随之由孔间围岩弱化阶段过渡到孔壁裂纹成形阶段,再转变为孔间围岩破断阶段。密集钻孔孔间围岩所受拉剪应力大小主要取决于关键岩层厚度及钻孔孔径与孔间距之比,与钻孔高度及间距成负相关,与角度及直径正相关。据此提出了密集钻孔关键参数确定方法,并根据龙滩矿3124 N工作面坚硬顶板条件设计了密集钻孔切顶留巷方案,确定钻孔长度为8.3 m,角度为15°,钻孔直径为48 mm,间距为500 mm。留巷后巷道顶帮变形可控且整体稳定性较好,由此可证明密集钻孔布置参数较为合理,密集钻孔关键参数确定方法有效可行。

非线性曲面梁形态优化及恒压支撑装置设计

基于超前支护设备顶梁支撑结构研究一种恒压支撑装置的设计方法,恒压支撑装置由正刚度线性弹簧、负刚度非线性平面曲梁及承压气囊组合而成。通过对巷道顶板应力场分析,得到支撑结构的边界条件;利用B样条曲线简述负刚度非线性平面曲梁的特点;基于遗传算法与非线性有限元法对负刚度非线性平面曲梁进行形态优化设计;依据恒压支撑装置的工作原理,对线性螺旋弹簧刚度/强度特性进行分析与设计;对恒压支撑装置的零部组件进行设计,实现支撑装置输出压强大小恒定及自我保护功能。恒压支撑装置设计方法为综掘巷道超前支护研制提供了有力技术支撑。

新疆高校新生身体形态指标和血压的特征及关联性研究

目的了解新疆高校新生身体形态指标与血压的特征及差异性,分析其关联性,为新疆高校新生高血压防治和干预提供参考依据。方法采用随机抽样对新疆4所高校的1853名18~21岁大学新生进行身体形态、腰围、臀围、血压等指标测量,根据受试者血压分为正常血压组和血压偏高组,分析不同性别、民族、年龄段新生血压的差异;统计学方法采用χ^(2)检验、Pearson相关性分析、Logistic回归分析及受试者操作特征(receiver operating characteristic,ROC)曲线分析。结果女生的体脂率(percent body fat,PBF)和体脂量高于男生[(24±8)%与(18±7)%,t=-17.95,P<0.01);(18±7)kg与(14±7)kg,t=-4.27,P<0.01],其他指标均低于男生;除体脂率外,汉族学生的身体形态指标均高于少数民族(P值均<0.01)。男生的血压偏高检出率高于女生[51.5%(538/1044)与42.4%(343/809),χ^(2)=15.250,P<0.01];汉族血压偏高检出率高于少数民族[59.4%(372/626)与41.5%(509/1227),χ^(2)=53.503,P<0.01];18~19岁新生的血压偏高检出率高于20~21岁[(51.4%(348/677)与45.3%(533/1176),χ^(2)=6.369,P<0.05)]。不同性别血压偏高组的身体形态指标均>正常血压组;大学新生收缩压与舒张压与身体形态呈现不同程度的相关性,多因素Logistics回归分析结果显示,男生的身体质量指数(body mass index,BMI)、PBF、体脂量、内脏脂肪等级(visceral fat level,VFL)、腰臀比(waist to hip ratio,WHR)和女生的体质量、BMI、体脂量、VFL超标以及女生体表面积(body surface area,BSA)下降都会增加血压偏高的风险;不同身体形态指标对血压偏高的曲线下面积(area under the curve,AUC)均>0.5,且男生的每项指标AUC均大于女生,其中男生身体形态中有多项指标与血压偏高的AUC>0.65。结论身体形态指标对男生血压偏高的诊断意义大于女生,尤其是PBF指标,全身性肥胖,特别是皮下脂肪肥胖与血压的相关性较高。

爆炸荷载下聚脲涂覆含局部缺陷油气管道的失效判定研究

通过埋地静爆试验,对经聚脲弹性体材料加固的含局部缺陷埋地油气管道抗爆性能及损伤评价进行研究,同时结合所得试验数据进行数值模拟,建立了浅埋爆炸荷载下聚脲弹性体材料加固含局部缺陷埋地油气管道损伤失效评估准则。结果表明:在折合距离为0.23 m/kg 1/3试验条件的浅埋爆炸荷载作用下,含局部缺陷普通管道与含局部缺陷聚脲管道迎爆面均发生了明显凹陷变形,含缺陷聚脲管道凹陷变形量较前者降低28.87%,且管道迎爆面及端部连接处易于遭受损伤;含局部缺陷普通管道迎爆面超压高于含局部缺陷聚脲管道且变形响应时间早于后者,表明聚脲材料可以有效降低爆炸冲击波压力峰值和推迟爆炸冲击波的作用时间。在进行爆炸荷载作用下管道的损伤失效判定时引入衡量管道横截面变形的截面临界椭圆度指标,最终建立了基于管道截面临界椭圆度的聚脲涂覆含局部缺陷埋地油气管道的超压-冲量损伤准则及判定公式。

基于斑马算法优化支持向量回归机模型预测页岩地层压力

针对陇东地区三叠系延长组7段(长7段)页岩孔隙结构复杂、非均质性强、地层压力预测精度较低等问题,提出了一种基于斑马算法优化支持向量回归机(ZOA-SVR)模型预测地层压力的方法,并在实际钻井中进行了应用,将预测结果与基于机器算法的模型和常规地层压力预测方法结果进行了对比。研究结果表明:①ZOA-SVR模型以实测地层压力数据为目标变量,优选与陇东地区长7段页岩地层压力数据关联度达到0.70以上的深度、声波时差、密度、补偿中子、自然伽马、深侧向电阻率、泥质含量等7个参数作为输入特征参数,设置训练样本数为40,交叉验证折数为5,初始化斑马种群数量为10,最大迭代次数为70,对惩罚因子和核参数进行优化并建模,参数优化后拟合优度指标R2达到0.942,模型预测的地层压力数据在训练集和测试集上的绝对误差均低于1 MPa,预测测试集地层压力数据与实测压力数据的平均相对误差为2.42%。②ZOA-SVR模型在研究区长7段地层压力预测中优势明显,比基于粒子群优化算法、灰狼算法和蚁群算法的模型具有更好的参数调节及优化能力,R2分别提高了0.209,0.327,0.142;比等效深度法、Eaton法、有效应力法预测的地层压力精度更高,相对误差分别降低了32.53%,15.31%,5.91%。③ZOA-SVR模型在实际钻井中的应用结果显示,研究区长7段地层压力在垂向上分布较稳定,泥页岩段的地层压力高于砂岩段,地层压力系数主要为0.80~0.90,整体上属于异常低压环境,与实际地层情况相符。

基于广义波阻抗理论的SHPB试验中弹性压缩阶段试件应力-应变曲线的应力波效应及其影响机理

定量研究分离式霍普金森压杆(split Hopkinson pressure bar,SHPB)试验中弹性压缩阶段试件中的应力波效应是解耦准确材料弹性曲线的基础。在满足平面波假设的基础上,基于广义波阻抗理论,对杆与试件面积不匹配时试件弹性压缩阶段应力波演化造成的结构效应开展了定量理论研究,分析了不同情况下弹性阶段内试件唯象工程及实际材料应力-应变曲线的偏差特征与主要因素,并揭示了影响这种偏差的影响规律及其机理。研究表明:对于线性入射加载波,当无量纲时间为0.5的倍数时,即使其他参数改变,试件唯象与材料实际的应力-应变曲线仍对应相等;试件两端的应力差较大时,若应力差的变化趋于稳定,则试件唯象与材料实际的应力-应变曲线差异较小。计算了不同波动区间内试件的最大应力偏离值及其变化趋势和对应的无量纲时间,研究了入射波是双线性组合波时试件的应力-应变曲线。研究表明:双线性波入射时,2个线性区间可以独立分析,无论如何组合线性区间或应力差如何变化,只要试件两端应力差为近似恒定曲线,对应的试件唯象工程应力-应变曲线都是相对准确的。

基于压力角的摆线针轮齿廓曲线优化方法

根据摆线针轮传动理论,提出一种基于压力角的齿廓优化方法。将摆线针轮齿廓分为工作段与非工作段,区分影响工作段压力角的因素为修形参数与设计参数,讨论两类参数对压力角的影响,以此两类参数为设计变量,以工作段平均压力角为目标函数,以运动与润滑要求确定边界条件,对RV⁃550E型减速器摆线轮进行优化设计。结果表明,此方法使算例的工作段平均压力角降低了4.14%,使单齿啮合过程的压力角最大值降低了1.35%,优化前后接触齿对最大Mises应力下降了20.77%,发生位置由摆线轮转移至针轮,模型质量减小了9.38%,在确保无根切现象的同时能获得良好的组合修形效果。

基于停泵压降曲线的压裂窜扰效果定量评价--以吉木萨尔页岩油平台井为例

针对目前缺乏压裂窜扰效果定量评价方法的难题,创新提出一套基于停泵压降曲线的压裂窜扰效果诊断分析方法。结合井组拉链式压裂工艺,提出了4种典型窜扰模式下的停泵压降曲线,用以诊断压裂窜扰类型。选取吉木萨尔页岩油A平台6个典型压裂窜扰段开展实例应用,通过与微地震监测结果对比,验证了方法的有效性。在此基础上,利用压降试井解释方法对吉木萨尔“新井组内部压窜”和“新老井间压窜”两种典型的停泵压降曲线开展拟合分析,反演解释缝网参数。解释结果表明,新井组内部压窜使主次裂缝的改造效果均受到影响,具体影响效果因窜扰类型的不同而存在差异;新老井间压窜主要影响主裂缝的改造效果,导致缝网由“长宽”向“短窄”转变,有效体积降低28%,整体改造效果变差。

对置端曲面齿轮柱塞泵动态特性仿真研究

为了研究对置端曲面齿轮柱塞泵参数对泵动态特性的影响,根据端曲面齿轮柱塞泵工作原理,推导柱塞运动方程。利用Adams与AMESim软件建立对置端曲面齿轮柱塞泵联合仿真模型,通过联合仿真得到不同转速与偏心率下的柱塞泵出口流量与压力的相应曲线。结果表明:转速增大,泵出口流量与压力增大,脉动幅值与脉动频率增大;偏心率增加,泵出口流量与压力增大,脉动幅值增大,脉动频率不变。

基于压力-冲量曲线的水下爆炸压力-时间公式

根据材料受冲击载荷时的压力-冲量函数,推导得到了适用于水下爆炸冲击载荷的压力时程公式。通过水下爆炸实验方法测量不同药量、不同距离的压力时程曲线,使用MATLAB软件对实验数据进行拟合,由此计算冲击波冲量和能量参数,并与通用的Cole与Орленко理论计算结果进行对比,验证拟合曲线的准确性。相较于Cole和Орленко理论,新方法得到的压力衰减曲线更接近实验值。计算水下爆炸冲击波的比冲量和比冲击波能时,新模型具有较高的计算精度,其中:比冲量与实验值的误差不超过4%,与Орленко理论相比,精度提高了5%~10%;比冲击波能与实验值的误差不超过1%,计算精度与通用理论相当。