A time domain induced polarization relaxation time spectrum inversion method based on a damping factor and residual correction

Relaxation time spectra （RTS） derived from time domain induced polarization data （TDIP） are helpful to assess oil reservoir pore structures. However, due to the sensitivity to the signal-to-noise ratio （SNR）, the inversion accuracy of the traditional singular value decomposition （SVD） inversion method reduces with a decrease of SNR. In order to enhance the inversion accuracy and improve robustness of the inversion method to the SNR, an improved inversion method, based on damping factor and spectrum component residual correction, is proposed in this study. The numerical inversion results show that the oscillation of the RTS derived from the SVD method increased with a decrease of SNR, which makes it impossible to get accurate inversion components. However, the SNR has little influence on inversion components of the improved method, and the RTS has high inversion accuracy and robustness. Moreover, RTS derived from core sample data is basically in accord with the pore-size distribution curve, and the RTS derived from the actual induced polarization logging data is smooth and continuous, which indicates that the improved method is practicable.

Use of Plastic Correction Formula to Improve Accuracy of Welding Residual Stress Test with Blind-Hole Method

The blind-hole method is the most widely used approach to experimentally determine the distribution of residual stress. This paper aims to improve test accuracy of welding residual stress and conducts an experimental study on the strain release factors involved when using the blind-hole method for Q235 and Q345, two steels commonly used in building structures. The ranges of strain release factors A and B in the elastic stage, the effects of strain release factors on residual stress calculated values, and the plastic corrected strain release factors are analyzed considering of the effect of plastic deformation around the blind hole on measurement accuracy. Finally, a simplified calculation formula to determine strain release factors is proposed for use with the blind-hole method. Results show that in the elastic stage, strain release factor A for Q235 and Q345 ranges from-0.399 to-0.525 and strain release factor B from-0.791 to-0.960. Changing the strain release factors A and B shows that calculated residual tensile stress varies in relation to a decrease in both factor values. However, there is a increase in calculated residual compressive stress with a decrease in the strain release factor A value, but there is an decrease with a decrease in strain release factor B value. Calculated residual stress applied to elastic strain release factors is compared with that applied to amended plastic strain release factors for Q235 steel. The maximum deviation between calculated residual stress and test stress is reduced from 21.1 to 1.0%,and for Q345 steel from 26.5 to 1.2%. It is thus evident that the plastic correction formula proposed in this paper can be used in calculations when conducting a residual stress test.

Delaware Method Improvement for the Shell and Tubes Heat Exchanger Design

In this paper the Delaware Method published in 1963 is analyzed and upgraded with using correction factors which take into account the undesirable currents of the mean flow. However, this method presents graphically these correction factors which imply an impediment to fulfill the software calculations. Thus, the equations corresponding to the correction factor equations and a Fortran 77 numerical program were established. This system is given to explore different design alternatives in order to find the optimal solution to each proposed problem. The results of this work was a simple software that can perform calculations with the introduction of parameters depending only on the geometry of the heat exchanger, i.e., geometry, temperature and fluid characteristics eliminating the human errors and increasing the calculations speed and accuracy.

A Dynamical Model to Analyze the Influence of Sliding Friction on Motion on a Curve—An Analytical Method

To demonstrate the influence of sliding friction of motion on a curve, a circular path is considered for simplicity on which a person slides from the highest point to the lowest point. A slide which represents a quadrant of radius 5 m and a person of mass 60 kg are considered for comparison in this paper. A Differential equation for motion considering the fact that the normal force depends both on the sin component of weight and also on the tangential velocity, is established and is solved using integrating factor method, and the motion is analysed for different surface roughness of the slide and is compared using superimposed graphs, also the limiting value of friction coefficient at which the person just exits the slide is determined. The correction factor for exit velocity with friction as compared with the exit velocity for zero friction is determined. The fraction of energy lost to friction at the exit is evaluated. The Variation of normal force with the position of the person on the slide is plotted for different surface roughness of the slide, and the position on the slide where the normal force or the force experienced by the person is maximum, is determined and hence its maximum value is evaluated for different surface roughness. For simplicity, a point contact between the body and the slide is considered.

一测多评法测定莲芝消炎胶囊中4种二萜内酯

目的:建立一测多评法测定莲芝消炎胶囊中新穿心莲内酯等4种二萜内酯成分的含量。方法:色谱柱为Shimadzu Shim-pack C_(18)(250 mm×4.6 mm,5μm);流动相乙腈-0.1%磷酸水溶液,梯度洗脱;流速1.0 mL•min^(-1);检测波长为203 nm。以穿心莲内酯为参照,计算其他3种二萜内酯成分的相对校正因子,并测定其含量。结果:4种二萜内酯成分在各自范围内线性关系良好(r≥0.9999),平均加样回收率为100.0%~102.8%,RSD为1.1%~2.2%。一测多评法与外标法所得结果接近。结论:该方法快速准确,重复性好,可用于莲芝消炎胶囊的质量控制。

引入重要度修正因子的复杂光电系统可靠性分配研究

以某新型复杂光电系统为研究对像,针对传统评分分配法客观性差、分配偏差大的缺点,构建重要度修正因子,提出了一种引入重要度修正因子的可靠性评分分配法。首先,运用模糊层次分析法,得到功能单元对上级功能单元/系统可靠性影响的相对重要度;然后,基于相对重要度,按照专家评分规则,得到功能单元对上级功能单元/系统可靠性影响的绝对重要度;最后,基于相对重要度和绝对重要度,构建功能单元重要度修正因子,以此修正各功能单元的评分结果。经对比验证,关重功能单元可靠性分配值较传统评分分配值至少提高6%,引入重要度修正因子的评分分配法能有效削弱传统评分分配法的主观影响,释放关重功能单元可靠性余量,提高功能单元可靠性分配的科学性、合理性,进而提高复杂系统可靠性设计水平。

前维生素D相对校正因子的研究及测定

目的:测定前维生素D相对校正因子,简化维生素D含量测定的计算方法。方法:通过对各国药品标准中维生素D含量计算方法的研究,采用HPLC法测定前维生素D相对校正因子,并对测定的影响因素进行了考察。结果:统计了国内7家实验室的前维生素D相对校正因子的测定结果,确定了254 nm和265 nm 2个波长下的前维生素D相对校正因子。结论:采用前维生素D相对校正因子法计算维生素D的总量,简化了实验步骤,避免了随机操作误差。该方法快速、准确,为进一步提高维生素D制剂标准奠定了基础。

双标多测法在枣仁安神颗粒6个成分含量测定中的应用

目的建立枣仁安神颗粒中斯皮诺素、6'''-阿魏酰斯皮诺素、迷迭香酸、五味子醇甲、五味子乙素和丹酚酸B 6个成分的双标多测法,验证该方法在枣仁安神颗粒质量评价中应用的准确性和可行性。方法采用HPLC法,以乙腈为流动相A,0.2%冰醋酸溶液为流动相B,梯度洗脱,流速为1.0 mL·min^(-1),切换波长320 nm(斯皮诺素、6'''-阿魏酰斯皮诺素、迷迭香酸、丹酚酸B)、250 nm(五味子醇甲、五味子乙素),柱温28℃。采用5根不同的C_(18)色谱柱,测定枣仁安神颗粒6个成分的实际保留时间,计算各成分在各色谱柱保留时间的平均值,得到各成分的标准保留时间,选取斯皮诺素(峰1)、五味子乙素(峰6)作为双标化合物,使用双标线性校正法准确定位各成分色谱峰,预测成分在未知色谱柱的保留时间并进行方法学验证。以五味子乙素为参照物,计算其余各成分的相对校正因子,对各成分进行定量。结果双标线性校正法能够准确地预测待测组分在未知色谱柱上的保留时间;斯皮诺素、6'''-阿魏酰斯皮诺素、迷迭香酸、五味子醇甲和丹酚酸B相对于五味子乙素的相对校正因子分别为0.7342、0.6063、0.5664、0.9975及0.7773,其RSD均小于1%;各成分含量计算值和实测值无显著差异。结论双标多测法同时测定枣仁安神颗粒中6个成分可行且准确。

基于PSYPRO露点水势的土体吸力测量方法研究

土体吸力测量对岩土工程稳定性评估至关重要,实时准确量测土体从饱和状态到干燥状态的吸力变化一直是非饱和土力学领域的研究热点和难点。露点水势技术是一种新型土体吸力测量方法。详细介绍了PSYPRO露点水势仪的工作原理以及所需要调试参数的意义,并结合标定试验和蒸发试验给出了PSYPRO露点水势仪测量土体不同吸力区间的最优参数设置推荐。先利用不同浓度NaCl溶液对PST-55湿度计进行标定试验并得到了校正系数,随后开展室内土体蒸发试验,并使用PST-55湿度计和ML3土体含水率传感器分别测量干燥过程中土体吸力和含水率变化,验证了露点水势技术用于土体吸力实时连续监测的可行性和准确性。

Phase Angle Control Based Three-phase DVR with Power Factor Correction at Point of Common Coupling

This paper investigates the ability of correcting the power factor at the point of common coupling(PCC)of the source side using dynamic voltage restorer(DVR).By applying the phase angle control(PAC)method,the DVR compensating voltage will be injected with a specific phase angle and magnitude in series with the transmission line,which leads to a power factor angle shift of the resultant load voltage.As a result,the source voltage is always in phase with the source current under different load conditions,which means that the power factor correction is achieved at the PCC of the source side.A laboratorial prototype of the DVR is utilized to verify the proposed control algorithm.The experimental results validate that an approximate unity power factor can be maintained at the source side.

不同截面形式钢-混组合梁桥面板横向受力性能分析

为研究不同截面形式对钢-混组合梁桥面板横向弯曲效应的影响,以山东九龙东枢纽天桥为背景进行研究。采用有限元软件建立4种截面主梁(波形钢腹板工字梁、波形钢腹板箱梁、平钢板工字梁及混凝土箱梁)精细化模型,对比分析轮载作用数量、轮载横向作用位置对桥面板有效分布宽度的影响,同时对自重、轮载作用以及二者共同作用下的桥面板横向弯矩进行分析,并与《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018,简称《桥规》)计算值进行对比。结果表明:双轮载作用下的桥面板有效分布宽度明显大于单轮载作用下的桥面板有效分布宽度,横向设计时应考虑轮载作用数量对桥面板安全设计的影响;钢-混组合梁桥面板有效分布宽度计算时,当轮载作用在横向跨中、支承附近处,采用《桥规》计算,当轮载作用在支承、悬臂板处,建议桥面板有效分布宽度修正系数分别取0.60、1.50;建议波形钢腹板工字梁、波形钢腹板箱梁、平钢板工字梁桥面板弯矩修正系数在轮载作用下分别取0.60、0.60、0.65,在自重、轮载共同作用下分别取0.55、0.55、0.60。

基于类比分析法的光伏电站发电能力评估模型研究

在光伏电站建设前期做可行性评估的过程中,需要对拟建光伏电站的发电量进行理论上的预测,以此来测算项目的投资收益率,进而评估项目是否值得投资建设。光伏电站发电能力评估的准确性受限于气象数据的准确性及光伏电站系统效率(PR)评估的准确性。由于环境复杂性高、实际测量难度大等原因,导致无法获得拟建光伏电站真实的气象数据及准确的PR。将拟建光伏电站周边的光伏电站作为参考,引入参考光伏电站的历史发电数据,结合参考光伏电站与拟建光伏电站的太阳辐射量差异、PR差异,提出了一种基于类比分析法的光伏电站发电能力评估模型。通过建立评估模型,解耦气象因素偏差对光伏电站PR的影响,分析各因素导致的评估模型的偏差范围,并采用3组光伏电站对照组的发电数据对评估模型的准确性进行了验证。研究结果表明:气象因素偏差对光伏电站PR的最大影响为1.5972%。采用该评估模型测算得到的3组光伏电站对照组的年等效利用小时数评估偏差皆控制在3.00%以内,平均偏差为1.21%,远低于采用PVsyst软件测算得到的年等效利用小时数的平均偏差。表明该评估模型具有良好地准确度,可作为光伏电站建设时评估其发电量的实用且有效的方法。

气相色谱法分析工业丙烯腈中的杂质

以氮气为载气,选用酸改性聚乙二醇(FFAP)毛细管色谱柱对工业丙烯腈中杂质进行了定性分析,并采用校正面积归一化法进行了定量分析。结果表明:采用该方法并根据有效碳数理论,以丙烯腈替代丙腈、顺式(或反式)-丁烯腈替代甲基丙烯腈,测定丙烯腈标样中杂质的回收率为90.1%~106.8%,相对标准偏差为0.8%~7.5%,检测限低于6.6μg/g;对丙烯腈产品中杂质分别采用校正面积归一化法及内标法定量时,同一组分的3次测量结果的重复性良好,2种计算结果无显著差异。

注射用泮托拉唑钠中有关物质研究

目的提高注射用泮托拉唑钠中有关物质的质量标准。方法色谱柱为Thermo Hypersil ODS C18柱(125 mm×4.0 mm,5μm),流动相为0.01 mol/L磷酸二氢钾缓冲液(用20%磷酸调pH至7.0)-[水-乙腈(1∶99,V/V)],梯度洗脱,流速为1.0 mL/min,检测波长为290 nm(杂质A,B,D+F,E)和305 nm(杂质C),柱温为40℃,进样量为20μL。采用加校正因子的主成分自身对照法计算有关物质的含量,杂质A,B,D+F,E按校正因子1.0计算,杂质C按校正因子0.3计算。结果在拟订色谱条件下,出峰顺序依次为杂质C、杂质A、泮托拉唑、杂质D+F、杂质E、杂质B,泮托拉唑与杂质D+F的分离度大于3.0;杂质A、杂质B、杂质C、杂质D+F、杂质E、泮托拉唑的检测限分别为0.24,0.29,0.80,0.71,0.30,0.30 ng。调整流动相梯度洗脱程序后,杂质D和杂质F的分离度大于1.0;检测限均为0.01μg/mL;加样回收率均在90%~110%范围内,RSD低于10.0%(n=9)。6批注射用泮托拉唑钠样品中均检出杂质A(C16H15N3O5F2S)、杂质C(C8H6F2N2OS)、杂质D+F(C17H17F2N3O4S,对映异构体)。结论该方法操作简单、专属性强,可用于注射用泮托拉唑钠中有关物质的质量控制。拟订杂质A、杂质C、其他单个杂质含量均不得过0.2%,杂质B、杂质E含量均不得过0.1%,杂质D、杂质F含量均不得过0.5%,总杂质含量不得过1.0%。

水质总α、总β放射性的测定厚源法串道比公式探究

在《水质总α放射性的测定厚源法》(HJ898—2017)、《水质总β放射性的测定厚源法》(HJ899—2017)中,串道比计算公式有多余项。本文通过理论推导和实验方法进行了验证。结果表明,根据该串道比计算公式给出的结果有更大的偏差估计。

ITTC 2021与ISO 15016航速修正应用对比

为了解ITTC 2021航速修正方法的适用性,论文介绍了该方法在船舶测速过程中的试验要求和修正流程,并将该方法与ISO 15016∶2015方法进行了对比。结合航速修正原理,通过编程的方式开发了2种方法的实船航速修正程序,并选用3种典型船舶的试航数据,分别采用上述修正方法进行分析,总结了2种修正方法在不同风、波浪、潮流、温度、密度和水深等环境因素下对修正结果的影响。结果表明:ITTC 2021修正方法相对于ISO 15016∶2015方法更为合理,且针对研究的3种船型,ITTC 2021方法得到的航速略高于ISO 15016∶2015修正方法,而新增的波浪增阻修正方法是导致分析结果产生偏差的主要因素。

基于一测多评法同时测定脑心舒通胶囊中6种成分的含量

目的:建立HPLC一测多评法同时测定脑心舒通胶囊中6种成分(丹参素、原儿茶醛、羟基红花黄色素A、迷迭香酸、天麻素、丹酚酸B),使用外标法验证此方法在脑心舒通胶囊中质量控制应用的可行性及适应性。方法:以丹参素为内标物,建立其与其他5种成分间的相对校正因子,并计算脑心舒通胶囊各成分含量,实现一测多评。结果:丹参素与其他五种成分的相对校正因子分别为1.025、2.157、0.760、1.820、6.224;9批脑心舒通胶囊中用一测多评法测定6种成分的含量与外标法测定结果无显著差异(相对误差<5%)。结论:该方法准确可靠,可用于脑心舒通胶囊的质量控制。

一测多评法同时测定车前草中4种活性成分的含量

目的:建立一测多评法(Quantitative Analysis of Multi-Components by Single Marker,QAMS)同时测定车前草中原儿茶酸、儿茶素、槲皮素和木犀草素的含量,并验证此方法的可行性及适应性。方法:以槲皮素为内标物,建立其与其他3种成分间的相对校正因子,并计算4种成分含量,实现一测多评。结果:槲皮素与其他3种成分的相对校正因子分别为1.199 2、0.861 3、1.606 9;采用一测多评法测定的10批次车前草中4种活性成分的含量与外标法测定结果无显著差异。结论:该方法准确稳定,可用于车前草多指标质量控制。

校正因数法在长歧水文站水位流量单值化分析中的应用

采用防城河长歧水文站2011-2020年水位、流量实测资料,利用校正因数法对其水位流量关系进行单值化分析,结果符合规范关于流量间测的规定和要求,该站水位在29.40-35.00m水位级内可实行间测,间测期间采用历年水位流量关系综合曲线推求流量,其他水位按原测验方案进行测验并推流。

基于色谱仪对乙酸乙酯精制产品纯度测定方法的比较研究

为准确、高效测定出乙酸乙酯精制产品纯度,基于气相色谱仪的分析条件下,按照程序升温方式进行分离,初设定温度80℃,保持4 min后并以20℃/min的升温速率开始升温,终止温度140℃,分析得各峰分离度均大于2.0,峰型对称、尖锐且基线平稳,可进行有效分离。经过面积归一化法、校正因子法与内标标准曲线法的定量分析对比,校正因子法具有准确度高、稳定性强且经济节约的特点,可得相对校正因子法对乙酸乙酯纯度的测定更具有适用性。