Indirect Methods of Detecting and Evaluating Inclusions in Steel—A Review

Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observation, tracer studies of determining exogenous inclusions from slag and lining erosion, SEN clogging and final prod- uct tests. There is no single ideal method of detecting and evaluating inclusions in steel, so it is better to use several methods simultaneously to give a more accurate evaluation. Total oxygen content and nitrogen pickup in low carbon aluminum-killed steel as criterion of clean steel in many plants are summarized.

On the parameters for electrocaloric effect predicted by indirect method

The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combining the Maxwell equation and phenomenological theory. Since the procedure is similar to indirect measurement of the EC effect, the results can serve as a reference for experiments. The results suggest that（i） it is reasonable to use zero-field CP,（ii） optimized ？T should be 2 K,（iii） it is better to keep △E 〈 EC, and（iv） E1〈 EC. Here, EC is the coercive field of material.

Safety evaluation for railway vehicles using an improved indirect measurement method of wheel–rail forces

The wheel-rail force measurement is of great importance to the condition monitoring and safety evaluation of railway vehicles. In this paper, an improved indirect method for wheel-rail force measurement is proposed to evaluate the running safety of railway vehicles. In this method, the equilibrium equations of a suspended wheelset are derived and the wheel-rail forces are then be obtained from measured suspension and inertia forces. This indirect method avoids structural modifications to the wheelset and is applicable to the long-term operation of railway vehicles. As the wheel-rail lateral forces at two sides of the wheelset are difficult to separate, a new derailment criterion by combined use of wheelset derailment coefficient and wheel unloading ratio is proposed. To illustrate its effectiveness, the indirect method is applied to safety evaluation of rail- way vehicles in different scenarios, such as the cross wind safety of a high-speed train and the safety of a metro vehicle with hunting motions. Then, the feasibility of using this method to identify wheel-rail forces for low-floor light rail vehicles with resilient wheels is discussed. The values identified by this method is compared with that by Simpack simulation for the same low-floor vehicle, which shows a good coincidence between them in the time domain of the wheelset lateral force and the wheel-rail vertical force. In addition, use of the method to determine the high-frequency wheel-rail interaction forces reveals that it is possible to identify the high-frequency wheel-rail forces through the accelerations on the axle box.

Investigation of a cyanine dye assay for the evaluation of the biocompatibility of magnesium alloys by direct and indirect methods

Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility,biodegradability,and mechanical properties that are similar to natural bone.However,direct in vitro assessment of these materials in the presence of cells is complicated by degradation products from the alloy that lead to a false positive for the most commonly used cell adhesion and cell proliferation assays.In this paper,a cyanine dye was used to quantitatively evaluate the in vitro biocompatibility of a Mg AZ31 alloy by both direct and indirect methods.The cytotoxicity of the corrosion products was evaluated via an indirect method;a 25%decrease in cell viability compared to control samples was observed.Moreover,direct assessment of cell adhesion and proliferation showed a statistically significant increase in cell number at the surface after 72 h.In addition,the degradation rate and surface characteristics of the Mg AZ31 alloy were evaluated for both direct and indirect tests.The degradation rate was unaffected by the presence of cells while evidence of an increase in calcium phosphate deposition on the magnesium alloy surface in the presence of cells was observed.This study demonstrates that a cyanine dye based assay provides a more accurate assessment of the overall in vitro biocompatibility of biodegradable metals than the more commonly used assays reported in the literature to date.

A data-driven indirect method for nonlinear optimal control

Nonlinear optimal control problems are challenging to solve due to the prevalence of local minima that prevent convergence and/or optimality.This paper describes nearest-neighbors optimal control(NNOC),a data-driven framework for nonlinear optimal control using indirect methods.It determines initial guesses for new problems with the help of precomputed solutions to similar problems,retrieved using k-nearest neighbors.A sensitivity analysis technique is introduced to linearly approximate the variation of solutions between new and precomputed problems based on their variation of parameters.Experiments show that NNOC can obtain the global optimal solution orders of magnitude faster than standard random restart methods,and sensitivity analysis can further reduce the solving time almost by half.Examples are shown on optimal control problems in vehicle control and agile satellite reorientation demonstrating that global optima can be determined with more than 99%reliability within time at the order of 10-100 milliseconds.

Combined indirect and direct method for adaptive fuzzy output feedback control of nonlinear system

A novel control method for a general class of nonlinear systems using fuzzy logic systems （FLSs） is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.

Correlations between direct and indirect strength test methods

The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economical, less time-consuming, and easily adaptable to the field. The main aim of this study was to derive correlations between direct and indirect test methods for basalt and rhyolite rock types from Carlin trend deposits in Nevada. In the destructive methods, point load index, block punch index, and splitting tensile strength tests are performed. In the non-destructive methods, Schmidt hammer and ultrasonic pulse velocity tests are performed. Correlations between the direct and indirect compression strength tests are developed using linear and nonlinear regression analysis methods. The results show that the splitting tensile strength has the best correlation with the uniaxial compression strength.Furthermore, the Poisson's ratio has no correlation with any of the direct and indirect test results.

Indirect-approach method for specified-end points seismic ray tracing in three dimen-sional inhomogeneous media

Generally speaking, the factors of both medium and tectonic that give rise to heterogeneity of the earth crust and mantle structures should be taken into account simultaneously in three dimensional seismic ray tracing. In this paper, the three dimensional structure models are constructed with the model similar to generation system in computer aid design and manufacturing (CAD/CAM). Based on the algorithm proposed by Cerveny et al . for complete seismic ray tracing in complex three dimensional structures, a new technique called the indirect approach method for two point seismic ray tracing in three dimensional laterally heterogeneous media has been put forward, and its numerical computing examples were given.

火山灰质材料的火山灰活性检测方法综述

本文将火山灰质材料的火山灰活性检测方法分为直接法和间接法两大类。其中,直接法包括石灰吸收值法,火山灰反应程度评定法和酸、碱溶出度法;而间接法包括物理性能法,水化反应放热量法和物理、化学特征参数法。为正确指导火山灰活性检测方法的应用,本文详细介绍并比较了各检测方法的原理和特点。笔者认为,直接法可直接测定出火山灰质材料与Ca(OH)2反应的程度,但其操作和分析过程相对复杂;间接法可通过测定火山灰质材料对体系物化性能的影响或材料自身的物理、化学特征参数来评价其火山灰活性。本文从材料科学的角度厘清了各检测方法的适用对象,认为应根据不同的火山灰质材料的特性选择与其相适应的火山灰活性检测方法。

成都市郫都区人群TSH参考区间的建立及验证

目的采用间接法建立适用于成都市郫都区人群的性别、年龄特异的促甲状腺激素(TSH)参考区间。方法收集2022年3月至2023年8月成都市郫都区中医医院37514例患者的TSH数据,根据筛选标准对数据进行删减,采用偏度-峰度法进行正态性检验,Turkey法剔除离群值。不同性别和年龄TSH水平比较分别采用Mann-Whitney U检验、Kruskal-Wallis H检验。应用非参数法建立TSH参考区间,并采用2种方法验证其可靠性,当其与试剂说明书参考区间的相对偏差小于参考变化值(RCV)或用于验证人群时>90%的TSH结果在参考区间内,则证明结果可靠。结果共纳入25761例患者的有效TSH数据,男9363例,女16398例。按年龄段将其分为8个亚组,即10~<18、18~30、>30~40、>40~50、>50~60、>60~70、>70~80、>80~90岁,男性TSH参考区间依次为0.457~4.884、0.465~4.229、0.445~4.918、0.457~4.826、0.471~5.160、0.425~5.477、0.456~5.645、0.465~6.418μIU/mL,女性TSH参考区间依次为0.546~5.196、0.592~5.499、0.606~5.815、0.549~5.915、0.527~6.099、0.457~5.927、0.435~6.078、0.415~6.321μIU/mL。参考区间上限、下限与试剂说明书的相对偏差均小于RCV(49.85%);在用于验证人群时,各组均有大于90%的TSH结果在参考区间内。结论采用间接法建立了性别和年龄特异的成都市郫都区人群TSH参考区间,可为甲状腺疾病的精准诊疗提供参考依据。

基于间接核查法的流量计云在线运行核查方法

在供热物理设备网中,除不同规模的流量计群外,还设有大量与流量有关的设备及部件。本文研究了利用供热系统的机理、被核查流量计的相关参数、供热物理设备网中设置的具有流量特性的设备或部件来判断被核查流量计工作状态的方法,并在此基础上提出了流量计的云在线运行核查技术流程,以快速判断在线应用的流量计的技术性能是否满足使用要求,解决供热企业核查人员及核查仪器设备不足的缺陷,有效提升智慧供热系统数据质量和提高控制系统的安全。

水蒸气载热式锅炉烟气余热回收系统的节能量测量方法

烟气余热回收可有效降低锅炉的排烟热损失,减少燃料耗量和温室气体排放。近年来,作为一种高效的全热热回收方式,水蒸气载热式锅炉烟气余热回收系统已在实际工程中得到一定的应用,但由于其流程及能量转化关系较为复杂,人们对该系统节能量如何判定存在争议。本文在分析烟气余热回收系统及其各环节的能量平衡与转化关系基础上,提出了采用温度传感器、热计量表等常规仪表间接测量整个余热回收系统及其锅炉助燃风预热节能量的方法,并以山东临邑恒利热电厂为例给出了采用水蒸气载热式锅炉烟气余热回收前、后的测量结果。数据分析表明,对于蒸发量为176.90 t/h的锅炉,整个烟气余热回收系统的总节能量为10.86 MW,占锅炉产热量的8.46%,其中通过锅炉的进风预热加湿使锅炉加热助燃风节能1.73 MW,占余热总回收量的16%。该测量方法为水蒸气载热式锅炉烟气余热回收系统规模化应用提供了节能量在线实时监测的技术支撑。

鸡马立克氏病火鸡疱疹病毒间接免疫荧光检测方法的建立与比较

为建立鸡马立克氏病火鸡疱疹病毒(MDV HVT)的间接免疫荧光方法,将MDV HVT病毒接种96孔细胞板培养(CEF),72 h后用鸡抗马立克氏病病毒阳性血清作为一抗和兔抗鸡荧光抗体作为二抗,对反应条件进行优化,建立了间接免疫荧光方法(IFA)。并与经典的马立克蚀斑计数方法进行病毒滴度的测定比较,运用统计学方法分析,P小于0.05,相关系数为0.995,说明两种方法相关性很好,两种方法均可用于马立克氏病病毒的滴度测定。IFA方法较蚀斑计数方法操作简便快捷,可代替蚀斑计数方法用于马立克氏病活疫苗的病毒含量的初步测定,同时为2025年版《中国兽药典》马立克氏病活疫苗增加IFA鉴别检验方法积累实验数据。

地下工程竖井定向连接四边形法最优图形分析

为了提高地下工程竖井定向精度,阐释了连接四边形法竖井定向方法,用一个角和一条边为参数确定对称四边形,构建了连接四边形严密平差模型,采用间接平差进行网形精度评估。编写程序遍历条件角和条件边计算定向边精度,绘制等值线,定量分析连接四边形法最优图形。该研究对于地下工程竖井定向具有实际应用价值。

基于间接热力学方法的变换应力方法推导

金属等没有剪胀性的连续材料在根据试验结果建立屈服函数后,可以由Drucker公设及其相关联流动法则推论直接唯一地确定出与屈服函数一致的塑性势函数。但大量试验结果与理论分析都表明Drucker公设对于土材料这种有剪胀性的颗粒材料并不适用,所以更具普适性的热力学成了正确描述土材料塑性流动方向的必要条件。然而塑性流动方向无法只由热力学这一描述材料特性的必要条件唯一地确定,因此便出现了先由试验确定屈服面与塑性流动方向再对其进行热力学验证的间接热力学方法。此外,由于土材料在三维应力空间中不同洛德角对应子午面上的应力应变规律并不一致,因此一般会通过三维化方法来描述土材料在三维应力空间中的力学特性。三维化方法会使得不同子午面上的屈服面及塑性流动方向与三轴压缩状态下所建立的本构模型有所不同,导致三维化后的本构模型是否符合热力学原理成为新的问题。所以本文利用间接热力学方法推导了符合热力学原理的三维化方法,并通过构建变换应力空间将其整理为更有实用性的变换应力方法。

双重孔隙流体饱和介质弹性波散射二维IBIEM模拟

基于平面波势函数,采用间接边界积分方程法(indirect boundary integral equation method, IBIEM)研究了双孔隙流体饱和介质中弹性波入射下二维孔洞的散射特性。推导得到了双孔隙介质中全空间二维线源动力格林函数,并给出了各散射波的位移场和应力场。在数值精度验证的基础上,以双孔隙二维饱和全空间中孔洞为例,解决了平面P、SV波入射下的地震波散射问题。数值结果表明:双重孔隙介质中的位移幅值、环向应力幅值、孔隙压力变化规律与不同入射波形,入射频率,孔隙率和边界排水条件密切相关,位移幅值在低频(无量纲频率η≤2)入射时出现峰值。环向应力幅值与干土条件相比更为复杂,基质孔压与裂缝孔压的存在增大了双重孔隙饱和介质的能量效应,总体震动趋势大于干土条件,环向应力放大可达62%。

土体抗拉强度试验研究方法的综述

土体抗拉强度比抗压和抗剪强度数值更小,因此时常被忽略,造成理论及试验的落后。文中系统归纳了土体抗拉强度的间接和直接方法,对比分析了现有试验方法的优缺点,结果表明:(1)土体抗拉强度的单轴拉伸方法按照力的加载方向可以分为垂直法和水平法,而垂直法中土样破坏前上半部分的重量会影响试验的准确性;(2)常用的土样固定方式有粘结、锚固、摩擦力和夹持,它们各有优势,但夹持较前三者更便捷和可操作。最后,提出水平单轴拉伸试验的后续仍需优化的问题。如制样脱模中土样的损耗、土样受拉段应力分布差,无法适用于大骨料砾质土、土样固定方式繁琐、土样与平台间的摩擦力难以消除等。

连续小推力轨迹优化间接法研究进展综述

针对空间探测中连续小推力轨迹优化,总结了间接法在最优控制理论、初值估计和同伦延拓方法等方面的研究进展。首先介绍了连续小推力轨迹优化问题的建模及其相应的最优控制问题的状态方程、约束方程和性能指标,对比了两类主要优化方法,即直接法和间接法的求解思路与优缺点。随后总结了轨迹优化初步设计、间接法初值估计以及同伦延拓方面的研究进展,探讨了智能优化和深度学习在轨迹优化间接法中的应用,进一步结合当前大规模任务规划、实时最优控制等需求讨论了间接法的应用。最后,对连续小推力轨迹优化间接法的发展展望进行了总结。

基于振动信号的推移质输沙率监测研究

推移质输沙率精确测量是河流动力学的研究难点之一,传统的推移质直接测量方法受限于推移质运动的复杂性和测量仪器的局限性,无法对推移质进行长时间的连续监测。为了连续监测推移质运动,采用推移质间接测量方法,利用安装振动传感器的冲击板系统对推移质运动产生的振动信号进行高分辨率采集,提取振动信号特征值,并建立与推移质输沙率及流量之间的关系,进一步采用人工神经网络算法对推移质输沙率进行有效预测。结果表明:推移质振动信号的特征值均值与推移质输沙率有良好的相关性;中等流量条件的神经网络预测效果最佳,小流量条件的预测效果次之,大流量条件的预测效果相对较差,且其最优输入参数与流量及河床变化均有关系。

非洲猪瘟病毒P54蛋白原核表达及间接ELISA检测方法建立

【目的】建立一种具有良好特异性和敏感性的非洲猪瘟病毒(African swine fever,ASFV)抗体间接ELISA检测方法。【方法】根据ASFV P54蛋白基因序列进行大肠杆菌密码子优化,将优化后的P54序列克隆到pET-28a(+)质粒中,构建重组质粒pET28a-P54,利用大肠杆菌表达系统表达目的蛋白并用His镍柱进行纯化,经SDS-PAGE和Western blotting鉴定后,以纯化的P54蛋白作为检测抗原进行包被,建立一种间接ELISA方法,对包被条件、封闭液、封闭时间和血清孵育等反应条件进行优化后,对其临界值、特异性、灵敏性和重复性进行验证。【结果】SDS-PAGE结果显示,P54蛋白分子质量为42 ku,纯度在95%以上;Western blotting结果显示,P54蛋白与ASFV阳性血清能产生特异性反应。优化后的ELISA反应条件为:0.3125μg/mL抗原37℃包被1 h,5%脱脂奶粉37℃封闭1 h,1∶800稀释的血清37℃孵育2 h,1∶15000稀释的酶标二抗37℃孵育1 h。该ELISA检测方法仅与ASFV阳性血清产生特异性反应,与猪瘟病毒、猪细小病毒、猪繁殖与呼吸综合征病毒、猪圆环病毒2型、牛病毒性腹泻病毒、猪伪狂犬病病毒和乙型脑炎病毒的阳性血清均无明显交叉反应;该方法灵敏性较高,ASFV阳性血清稀释度为1∶3200时仍有明显反应。批间重复和批内重复变异系数均<10%;与商品化试剂盒相比,其阳性符合率为95.45%,阴性符合率为96.05%,总符合率为95.83%。【结论】本研究建立了一种以ASFV P54蛋白为检测抗原的ASFV间接ELISA方法,该方法具有良好的特异性和敏感性,能运用于ASFV的血清学检测,为非洲猪瘟的快速诊断提供更多选择。