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.

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。

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。

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%。

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。

自贡地区不同年龄阶段妊娠早期妇女甲状腺功能指标参考区间的建立

目的:采用间接法建立四川自贡地区健康妊娠早期妇女不同年龄阶段甲状腺激素测定的参考区间,为临床诊断和治疗提供依据。方法:选取自贡市第一人民医院妇产科建档的2019年1月至2021年12月健康妊娠早期妇女的数据,共1518例。根据孕妇年龄分为A组(<26岁)、B组(26~34岁)、C组(>34岁)3组,以2.5%至97.5%的百分位点数所在区域作为参考区间。对3个年龄阶段目标人群的促甲状腺激素(TSH)、总三碘甲状腺原氨酸(TT3)、总甲状腺素(TT4)、血清游离三碘甲状腺原氨酸(FT3)和血清游离甲状腺素(FT4)这5项甲状腺激素数据进行统计分析。结果:不同年龄妊娠早期妇女的TSH、FT3和FT4这3项指标之间无统计学差异,3组年龄合并的参考区间分别为TSH(0.12~3.81 mIU/L)、FT3(2.20~5.03 pmol/L)、FT4(4.79~16.13 pmol/L);不同年龄的TT3、TT4水平有统计学差异,其中年龄小于26岁的妊娠早期妇女的TT3、TT4的参考区间分别为1.04~2.78 nmol/L和91.80~204.88 nmol/L,而年龄大于26岁的妊娠早期妇女的TT3、TT4的参考区间分别为1.04~2.55 nmol/L和82.70~190.00 nmol/L。各指标年龄组A、B、C组与非妊娠组比较,差异均有统计学意义(P<0.05)。结论:建立的自贡地区不同年龄阶段妊娠早期妇女甲状腺激素5项指标参考区间,可为临床疾病诊断、治疗和预后判断提供参考。

间接法建立新疆克拉玛依地区常规肝功能和血脂生化项目参考区间

目的采用间接法利用大数据建立新疆克拉玛依地区常规肝功能和血脂生化项目参考区间。方法收集新疆克拉玛依市中西医结合医院(市人民医院)2018-2020年体检人群数据,并对数据进行删减、去重、正态性检验、数据对数转换和离群值剔除。采用Z检验考察参考区间年龄和性别分区,应用非参数法计算参考区间,并以参考变化值(RCV)作为验证依据验证该研究中建立的参考区间可靠性。结果纳入分析的有效数据为:总蛋白(TP)27492例,丙氨酸氨基转移酶(ALT)60798例,天冬氨酸氨基转移酶(AST)37080例,甘油三酯(TG)30287例,总胆固醇(TC)35778例,高密度脂蛋白胆固醇(HDL-C)34194例,低密度脂蛋白胆固醇(LDL-C)33087例,白蛋白(ALB)37893例。ALT、AST和TG的参考区间存在性别差异(Z>Z*)。新疆克拉玛依地区常规肝功能和血脂生化项目参考区间为TP 69~85 g/L,ALB 41~51 g/L,TC 3.06~6.00 mmol/L,LDL-C<3.81 mmol/L,HDL-C 0.87~1.91 mmol/L;ALT男性为9~42 U/L、女性为7~39 U/L,AST男性为14~30 U/L、女性为12~28 U/L,TG男性为0.55~2.20 mmol/L、女性为0.47~2.10 mmol/L。除ALB外,其余指标参考区间与现行参考区间相比,均小于RCV。结论间接法建立的肝功能和血脂生化项目的参考区间简单、可靠,可在该地区实验室推广和应用。

长春市不同年龄段健康成人血清心肌酶谱水平观察

目的参照实验室信息管理系统中健康成人数据,观察长春市不同年龄健康成人心肌酶谱水平,建立长春市成人肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)、乳酸脱氢酶(LDH)和α-羟丁酸脱氢酶(α-HBDH)的参考区间。方法选取2019年1月至2020年12月该院实验室信息管理系统中健康成人数据。采用K-S检验判断数据的正态性,对数转换呈偏态分布的数据,箱图法剔除离群值,LMS法拟合连续百分位数曲线,Z检验比较性别及年龄的差异;采用非参数法计算参考区间的上、下限,Bootstrap计算90%CI。对已建立的参考区间进行适用性验证。结果共纳入6831例20~79岁健康人群数据。除CK外,CK-MB、LDH、α-HBDH数据均服从正态分布,箱图法剔除数据277例。男性和女性CK、CK-MB水平比较,差异均有统计学意义(P<0.05)。各年龄组男性LDH、α-HBDH水平及女性CK、CK-MB、LDH、α-HBDH水平比较,差异均有统计学意义(P<0.05)。非参数法得出的参考区间为CK男性53.0~273.0 U/L(20~79岁),女性41.0~162.7 U/L(20~49岁)、女性42.0~187.8 U/L(50~79岁);CK-MB男性8.5~24.1 U/L(20~79岁),女性7.3~22.5 U/L(20~69岁)、女性7.5~24.9 U/L(70~79岁);LDH男、女性133.0~244.0 U/L(20~59岁)、144.0~264.0 U/L(60~79岁);α-HBDH男、女性74.0~167.0 U/L(20~49岁)、79.0~183.0 U/L(50~79岁)。LDH参考区间与少数研究参考区间的相对偏差均高于参考变化值。心肌酶谱各项目均通过适用性验证。结论长春市健康成人CK、CK-MB有性别差异,男性LDH、α-HBDH及女性CK、CK-MB、LDH、α-HBDH有年龄差异,健康女性CK,以及男、女性CK-MB、LDH、α-HBDH水平均随年龄增长呈逐渐上升趋势。

尿素醇解法合成碳酸二甲酯的研究进展

碳酸二甲酯是一种绿色、环保、性能优良的新型有机化工原料及合成中间体,应用范围十分广阔。尿素醇解法是碳酸二甲酯合成法之一,其具有原料廉价易得、过程安全及绿色环保等优点,受到了学术界及工业界的青睐。尿素醇解法合成碳酸二甲酯主要分为直接合成法和间接合成法。目前,直接法因存在转化率低等问题,还未实现工业化应用;然而,间接法合成碳酸二甲酯取得了重大突破,并已有多个企业建成了年产万吨级的生产车间,并投入到工业化生产中。本文对近年来尿素醇解法合成碳酸二甲酯的研究进展进行了综述。

基于重组核衣壳蛋白的猪德尔塔冠状病毒间接ELISA检测方法的建立

目的:建立一种关于猪德尔塔冠状病毒(Porcine Deltacoronavirus, PDCoV)抗体的检测方法。方法:对猪德尔塔冠状病毒的核衣壳蛋白(N)进行原核表达,通过Western Blot、SDS-PAGE等方法,对重组蛋白进行鉴定;在获得正确表达的重组蛋白后,以此为抗原,对ELISA反应条件进行优化,并对其特异性、敏感性、重复性进行测试,最终建立ELISA检测方法,并对临床样品进行检测。结果:优化后的抗原包被浓度为2μg/孔,37℃孵育1 h;1%BSA 37℃封闭1 h;一抗稀释最佳浓度为1∶1 600,孵育时间为1 h;酶标二抗最佳孵育时间为60 min。重组蛋白能与猪德尔塔冠状病毒血清发生特异性反应,所建立的检测方法具有优良的敏感性、特异性、重复性。结论:本研究建立了一种针对猪德尔塔冠状病毒的间接ELISA检测方法,为猪德尔塔冠状病毒的抗体水平检测及疾病的防控提供了一种有效的方法。

面向碳达峰碳中和的电网碳排放因子改进计算方法

精准、客观、有效的碳排放核算方法是服务碳达峰碳中和、支撑科学碳减排决策的迫切需要。当前电力用户的间接碳排放被纳入多个省级碳排放试点市场,同时也是各级行政机构进行碳排放统计核算的重要来源,因此电网碳排放因子事关国家碳减排工作大局,根据新形势需要及时完善电网碳排放因子计算方法意义重大。首先论述了电网碳排放因子概念和应用范围,随后梳理了国际典型电网碳排放因子发展现状,基于目前国内常用电网碳排放因子计算方法,从核算周期、核算范围等方面提出了优化建议,重点从有效衔接绿色电力消费的角度,设计了考虑绿色电力消费影响的电网碳排放因子改进算法。算例分析表明,所提改进算法能够更准确反映用户用电行为产生的间接碳排放水平,也能更有效促进绿色电力消纳发展。

P波入射下山体-隔震层-隧道的整体响应分析

采用高精度间接边界元方法(IBEM)开展了山体-隔震层-隧道的整体响应分析,研究了P波入射下柔性隔震层对高斯形山体内双线隧道地震动响应的减弱作用。在隔震层与围岩之间考虑了碎土的错动滑移,以模拟不完美交界面,并系统讨论了隔震层弹性模量、厚度、P波入射频率等因素对隧道地震动响应的影响。数值模拟结果表明:适当增加隔震层厚度可以显著降低隧道应力,有效提升隔震效果,应力降低幅度约达50%以上,且使得结构受力更为均匀;随着隔震层材料的弹性模量减小,隧道动应力数值明显减小,有效减少了其应力放大区的面积,从而有效避免因地震而导致的衬砌裂缝。

平面SV波入射下地上建筑群-地铁隧道群动力相互作用研究

该研究采用一种高精度间接边界元方法(indirect boundary element method, IBEM),研究了平面SV波入射下地上建筑群-地铁隧道群的动力相互作用问题。研究表明:“建筑群-隧道群”系统存在显著的动力相互作用,其规律与入射波性质、建筑物和隧道数量排布等因素密切相关。通过对比不同建筑物数量对隧道动力响应的影响,能够发现:低频波作用下,建筑物对下穿隧道的动力响应有放大作用,而高频波作用下则会削弱隧道的动力响应,最多可以降低37.5%左右。从频域分析中可以看出:隧道对地震波有较强的屏蔽作用,从而降低了其上建筑群的地震响应。建筑群的存在降低了各个单体建筑的动力响应,但在高频波作用时位于建筑群来波一侧的建筑会产生较大的动力响应。该研究成果可为城市建筑群-地铁隧道群的动力相互作用分析以及地上建筑和地铁隧道的抗震设计提供理论依据。