The Method for Optimum Design of Water Rocket Flight Stability Performance Conditions Using CAE with T Method and Robust Parameter Design

A water rocket is a rocket system that obtains thrust by injecting water with compressed air of up to about 8 atmospheres. It is usually manufactured using a pressure-resistant PET bottle. The mechanical elements and principles contained in the water rocket have much in common with the actual small rocket system, and are suitable as educational and research teaching materials in the field of mechanics. Especially in the field of disaster prevention and mitigation, the use of water rockets is being researched and developed as a rescue tool in the event of a flood or earthquake as a disaster countermeasure. However, since the water rocket is a flying object based on the mechanical principle, it is important to ensure the accuracy and stability of the flight path. In this paper, a mechanical simulator is developed with a numerical calculation program based on the mechanical consideration of water rocket flight performance. In addition, the correlation between the flight distance obtained in the simulation and the estimated flight distance is analyzed by applying a multivariate analysis method and verifying the validity of the flight distance calculated from the result. Based on the verification results, we will apply a statistical optimization method to approach the optimization of flight stability performance conditions for water rockets.

基于等效裂纹法的铝合金T形焊接接头疲劳寿命评估

针对焊接缺陷的多样性、复杂性及随机分散性等特征,提出一种以一组高应力疲劳试验结果作为参考点的等效裂纹法开展焊接结构的疲劳寿命研究。以疲劳试验结果作为参考,假设一个完整板中的初始裂纹等效焊接结构中的缺陷及应力集中效应,基于线弹性断裂力学和Paris公式计算等效裂纹扩展寿命作为焊接结构的疲劳失效寿命。提出基于等效裂纹法的结构疲劳寿命计算流程;开展铝合金T形焊接接头的疲劳试验以及拟合P-S-N曲线;基于T形焊接接头的焊根失效模式采用等效裂纹方法预测T形接头的计算P-S-N曲线,并与试验拟合曲线进行对比,相对误差为10%,验证了该方法的可行性与有效性;最后,通过一组变幅载荷谱疲劳试验与预测P-S-N曲线对比,相对误差均小于15%,同时也验证了该方法对于变幅载荷的适用性,实现了基于一组疲劳试验结果预测全范围T形焊接接头疲劳寿命的评估。以较少的测试和成本实现确定的疲劳寿命,简化了概率疲劳寿命的评估过程,该方法可以推广于其他焊接接头寿命评估中。

采用T型喷口的喷水推进船模阻力数值模拟

T型喷口是一种附加在喷水推进装置后方,改变水流纵向喷射方向为横向的模型试验装置。该装置只在船体内部流道上产生力的作用,既可反映常规喷口推进船模自航状态下,推进装置的抽吸作用对船尾边界层的影响,又对船身浮态影响很小,仅通过船模阻力试验和获流区PIV测试试验,结合动量通量法换算,可将常规推进船模自航试验中,推进系统对船体阻力的影响分离出来。通过CFD手段,采用流量边界条件法,对某带有T型喷口推进装置的船模阻力性能进行数值模拟,并与模型试验结果进行比较分析。最后,对T型喷口装置的工作原理进行说明。

计数标准型一次抽样检验方案设计方法探讨——兼议GB/T 13262—2008改进问题

GB/T 13262—2008是不合格品率的计数标准型一次抽样检查程序及抽样表,是一种针对大批量孤立批产品进行计数的两点型一次抽样检验,该标准对于抽样方案的确定方法繁琐、粗略,所获抽样方案存在不满足抽样原理的情况,抽样表限定生产方风险为0.05,使用方风险为0.1,不能满足人们的多样化需求。

A decomposition method of nuclear magnetic resonance T2 spectrum for identifying fluid properties

Based on analysis of NMR T2 spectral characteristics,a new method for identifying fluid properties by decomposing T2 spectrum through signal analysis has been proposed.Because T2 spectrum satisfies lognormal distribution on transverse relaxation time axis,the T2 spectrum can be decomposed into 2 to 5 independent component spectra by fitting the T2 spectrum with Gauss functions.By analyzing the free relaxation response characteristics of crude oil and formation water,the dynamic response characteristics of the core mutual drive between oil and water,the petrophysical significance of each component spectrum is clarified.T2 spectrum can be decomposed into clay bound water component spectrum,capillary bound fluid component spectrum,micropores fluid component spectrum and macropores fluid component spectrum.According to the nature of crude oil in the target area,the distribution range of T2 component spectral peaks of oil-bearing reservoir is 165-500 ms on T2 time axis.This range can be used to accurately identify fluid properties.This method has high adaptability in identifying complex oil and water layers in low porosity and permeability reservoirs.

The Consistency of the Solutions by T-Matrix Method with Canonical Solutions

In this paper, the limitation of T matrix structure is analyzed. It is found that a solution by T matrix method can be transformed to a canonical solution when the boundary of the scatterer tends to the cylindrical form and the scatterer is illuminated by E plane waves. It is concluded that a T matrix is diagonal with the scatter boundary in this limit situation. This is also the best result of numerical solution.

基于T-history法的脂肪酸相变材料的凝固-熔化动力学模型及关键参数

相变材料的熔化、结晶特性对相变储能具有重要意义,现有相变模型设定相分数与温度区间呈线性关系,未能考虑温度变化速率对相变过程的影响,因而在有关应用中的预测准确率较低。为研究温度与温度变化速率共同作用下的两相转化规律,对相变过程进行了理论分析,以相分数作为关键参数,通过固相和液相的PCM组分之间的可逆反应建立凝固-熔化动力学模型。设定Avrami方程作为模型中的反应函数,以Arrhenius方程作为模型中的速率函数。选用建筑领域常用的脂肪酸类相变材料正癸酸、月桂酸、辛酸作为实验材料,采用T-history法,通过等温结晶实验对Avrami方程进行拟合验证。经过验证证实Avrami方程与等温结晶实验所获得数据之间呈现出高度一致性与可靠性之后,通过非等温实验测试获得相变材料在不同温度与温度变化速率下的热力学信息,结合热分析动力学方法,对模型中的关键动力学参数研究测定。研究结果表明:活化能与常数因子变化趋势一致且存在互补效应,不同相变材料的活化能与常数因子大小不同,随相变过程进行,变化情况不同。反应级数随着温度变化速率的增大而减小,且凝固过程的反应级数普遍大于熔化过程。

Method of reverberation ray matrix for static analysis of planar framed structures composed of anisotropic Timoshenko beam members

Based on the method of reverberation ray matrix（MRRM）, a reverberation matrix for planar framed structures composed of anisotropic Timoshenko（T） beam members containing completely hinged joints is developed for static analysis of such structures.In the MRRM for dynamic analysis, amplitudes of arriving and departing waves for joints are chosen as unknown quantities. However, for the present case of static analysis, displacements and rotational angles at the ends of each beam member are directly considered as unknown quantities. The expressions for stiffness matrices for anisotropic beam members are developed. A corresponding reverberation matrix is derived analytically for exact and unified determination on the displacements and internal forces at both ends of each member and arbitrary cross sectional locations in the structure. Numerical examples are given and compared with the finite element method（FEM） results to validate the present model. The characteristic parameter analysis is performed to demonstrate accuracy of the present model with the T beam theory in contrast with errors in the usual model based on the Euler-Bernoulli（EB） beam theory. The resulting reverberation matrix can be used for exact calculation of anisotropic framed structures as well as for parameter analysis of geometrical and material properties of the framed structures.

The Method for Optimum Estimation of COVID-19 Variant Type Virus Infection Status Analysis by the Multivariate Analysis Considering the Environmental Variability Impact in Japan

Currently, the estimated value of the effective reproduction number (ERN), which is an index for grasping the COVID-19 infection status, is used for important planning and evaluation of infection prevention measures. Since ERN in the Sequential SIR model fluctuates in multiple dimensions due to changes in the surrounding environment, it is difficult to set the appropriate accuracy of the uncertainty region of the estimated data. The challenge in this study is to build a mathematical model of infectious disease according to the characteristics and data characteristics of the infectious disease and select an appropriate estimation method. Highly accurate quantitative research that analyzes the validity of “how infectious diseases prevail” from an academic point of view is the key to prediction and estimation in appropriate infection situation analysis. In this study, we adopted a statistical multivariate analysis method (T method) that enables evaluation and prediction of important factors related to ERN estimation and analysis of phenomena that change in real time (time series analysis). It was clarified that it is possible to estimate with higher accuracy by applying the T method to the estimated value of ERN by the current SIR mathematical model.

基于人脸识别的课堂教学行为S-T分析系统设计

提出并详细介绍了一种基于人脸识别技术的课堂教学行为S-T分析系统的设计。该系统以S-T分析法为理论基础,采用多种人脸识别算法,包括年龄检测、表情分析、姿态分析等,旨在自动识别并分析教师和学生在课堂上的行为。基于大量课堂视频数据的准备、软件系统原型的设计、深入研究课堂教学行为理论等,解决人脸识别技术的算法选型、视频关键帧的分析与因果关系模型的建立、系统运行的稳定性和界面设计等关键技术问题。通过系统性的需求分析、设计与架构、实现、评估与可视化等阶段的论述,详细展现了该系统的开发过程。

All-electron basis sets for H to Xe specific for ZORA calculations:Applications in atoms and molecules

A segmented basis set of quadruple zeta valence quality plus polarization functions(QZP)for H through Xe was developed to be used in conjunction with the ZORA Hamiltonian.This set was augmented with diffuse functions to describe electrons farther away from the nuclei adequately.Using the ZORA-CCSD(T)/QZP-ZORA theoretical model,atomic ionization energies and bond lengths,harmonic vibrational frequencies,and atomization energies of some molecules were calculated.The addition of core-valence corrections has been shown to improve the agreement between theoretical and experimental results for molecular properties.For atomization energies,a similar observation emerges when considering spin-orbit couplings.With the augmented QZP-ZORA set,static mean dipole polarizabilities of a set of atoms were calculated and compared with previously published recommended and experimental values.Performance evaluations of the ZORA and Douglas–Kroll–Hess Hamiltonians were made for each property studied.

T型截面铝合金型材零件成组加工技术研究与应用

针对目前飞机T型材零件单件弯曲成形效率低成形精确差的问题,提出了T型材弯曲件成组拉弯成形的成组加工方法。基于截面尺寸、引导线的曲率半径等信息建立了成组分析算法,对T型材进行分组,使用长型材拉弯成形后切割分段得到符合精确外形要求的T型材零件。通过理论计算、模拟分析和拉弯试验,验证了T型材拉弯成形成组加工技术的可行性,该方法提高了零件的制造效率和成形精度,可以大幅度降低人工矫正的工作量和加工成本。

遥感卫星地面站12米口径天线Ka频段G/T值测试方法综述

Ka频段G/T值是遥感卫星地面站12米口径天线最重要的指标之一,其测试方法与遥感站目前常用的X频段测试方法相比,适用条件更加严苛,因此如何选取最佳的测试方法成为本文研究的主要内容。首先介绍了Ka频段12米口径天线特点;然后分别论述了分段测试法、信标法、比较法和射电源法的原理及其优缺点,并提出了Ka频段对月测试的这一最方便简洁的测试方法及其修正系数的研究方向;最后通过实测结果进行比较,给出Ka频段G/T值测试方法选取建议,为工程师现场测试提供了科学的指导和参考。

基于NB/T 47065的容器支腿稳定性评价方法改进

针对NB/T 47065评价支腿稳定性未考虑外部管系附加弯矩影响的情况,完善了支腿反力公式,通过分析支腿两端弯矩比,进一步修正了弯曲应力公式,降低了弯曲应力保守量,并参考JB 4732、ASME BPVCⅢ等规范引入偶然载荷作用下许用应力系数,得到了一种与工程实际载荷组合一致,考虑等安全裕度原则的支腿稳定性评价方法。结合有限元分析算例,验证了该评价方法的保守性。

非中心t分布合格判定方法中k值计算

非中心t分布是批量产品电磁兼容符合性评定的重要统计技术之一,k值是非中心t分布合格判定方法中的关键参数,在GB/Z 6113.403-2020中仅给出了80%/80%准则的有限样本下的k值,且未给出具体计算方法。本文结合电磁兼容试验统计技术实际应用情况,从非中心t分布分位数表中有对应分位数概率(P)值而无置信度(α)值、无P值且无α值两方面进行计算方法研究,提出了适用于不同准则和不同样本的k值计算方法,对不同计算方法进行了对比研究分析,指出基于线性插值和指数逼近拟合算法的准确性、与标准的一致性较高,最后给出了两种典型的k参数计算值。旨在为电磁兼容非中心t分布试验符合性统计评定提供工程指导和参考。

养正透邪祛毒法联合NAC方案化疗对三阴性乳腺癌患者疗效、T细胞亚群及癌因性疲乏的影响

目的:探讨养正透邪祛毒法联合NAC方案(多西他赛+表柔比星+环磷酰胺)化疗对三阴性乳腺癌患者疗效、T细胞亚群及癌因性疲乏的影响。方法:选取2022年6月至2023年6月该院诊治的三阴性乳腺癌患者100例,根据随机数字表法分为对照组和观察组,各50例。对照组患者给予NAC方案治疗,观察组患者给予口服自拟养正透邪祛毒方与NAC方案联合治疗。观察两组患者的疗效、T淋巴亚群、炎症因子、癌因性疲乏水平及不良反应发生情况。结果:观察组患者的总有效率为82.00%(41/50),明显高于对照组的58.00%(29/50),差异有统计学意义(P<0.05)。治疗后,两组患者CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)、白细胞介素(IL)12和IL-2水平均较治疗前升高,且观察组患者较对照组更高;两组患者CD8^(+)、肿瘤坏死因子α和可溶性白细胞介素-2受体水平,躯体、认知和情感疲乏评分均较治疗前降低,且观察组患者较对照组更低,上述差异均有统计学意义(P<0.05)。观察组、对照组患者的不良反应发生率分别为24.00%(12/50)、28.00%(14/50),差异无统计学意义(P>0.05)。结论:养正透邪祛毒法与NAC方案化疗联合治疗三阴性乳腺癌患者,可明显提高疗效,改善T细胞亚群水平,降低炎症反应,改善癌因性疲乏状况,安全性佳。

On the basis of the morphology of the T-wave alternans: A Poincare mapping method research

Presently T-wave alternans (TWA) has become a clinical index of non-invasive diagnosis for heart sudden death prediction, and detecting T-wave alternate accurately is particularly important. This paper introduces an algorithm for detecting TWA using Poincare mapping method which is a technique for nonlinear dynamic systems to display periodic behavior. Sample series of beat to beat cycles were selected to prepare Poincare mapping method. Vector Angle Index (VAI), which is the mean of the difference between θi (the angle between the line connecting the i point to the origin and the X axis) and 45 degrees was used to present the presence or absence of TWA. The value of 0.9 rad ≤ VAI ≤ 1.03 rad is accepted as a level determinative for presence of TWA. VAI via Poincare mapping method (PM) is used for correlation analysis with T-wave alternans voltage (Vtwa) by way of the spectral method (SM). The cross-correlation coefficient between Vtwa and VAI is γ = 0.8601. The algorithm can identify the absence and presence of TWA accurately and provide idea for further study of TWA-PM.

Estimating GARCH Modeling Using Metropolis-Hastings Method in R

This paper mainly talks about a popular approach of volatility of a GARCH-type model in R, while the disturbances are independent and have identical Student-t distribution. It uses the Metropolis-Hastings method to perform the computations and gives the programs in details in R.

基于改进T-B法的宽带高斯过程疲劳损伤分析

针对宽带高斯随机应力过程造成的疲劳损伤问题,本文提出一种基于改进Tovo-Benasciutti(T-B)法的疲劳损伤频域分析方法。通过不同参数形式的功率谱进行时域的疲劳损伤分析,针对T-B法中的关键参数bTB提出一个新的非线性函数模型。与原T-B法相比,新提出的函数模型bMTB可以考虑S-N曲线斜率参数m的影响,并以此为基础提出基于改进T-B法的疲劳损伤分析方法。以时域的雨流计数法结果作为基准,分别采用参数化功率谱和真实响应谱进行数值试验,并与现有的多种宽带高斯疲劳损伤分析方法进行对比,验证本文所提出的改进T-B法的准确性和适用性。

公路T梁桥建设碳排放特征与规律分析

桥梁工程是公路建设碳排放的主要环节,T梁桥作为公路项目标准化制造的重要结构形式,掌握其碳排放特征和规律,有助于公路低碳建设和管理。研究采用排放因子法对23座典型T梁桥进行碳排放测算,划定了公路T梁桥建设边界范围,确定了碳排放测算功能单位,测算了各工程部位的碳排放强度,开展了参数敏感性分析和相关性分析,并提出了基于桥梁长度的桥梁主要结构碳排放估算模型。通过测算结果可知,公路T梁桥建设碳排放强度为8927.13 t CO_(2)e/(km·lane),变化区间为4002.64~9871.74 t CO_(2)e/(km·lane),其中间接碳排放占比为98.28%~99.13%,而直接碳排放为6820.99 t CO_(2)e。桥梁建设约86%碳排放主要集中在预应力T梁和桩基础,碳排放强度分别为1.23 t CO_(2)e/m^(3)、0.68 t CO_(2)e/m^(3);约95%来源于水泥、钢材、回旋钻机和交流电弧焊机。敏感性分析表明,当水泥、钢材、电力、化石燃料碳排放因子变化±(10%~30%)时,碳排放变化分别为±(4.77%~14.32%)、±(4.24%~12.74%)、±(0.57%~1.72%)、±(0.14%~0.43%)。相关性分析表明,桥梁主要工程部位的碳排放受桥梁规模影响较大,可基于桥梁长度快速估算T梁桥整体和各工程部位的碳排放。对此,项目管理者可通过低碳采购等方式降低间接碳排放;可通过优化加工工艺和施工方案等方式,在工程活动中节约材料、降低能耗;可通过降低用量和碳排放因子多种组合方式,对主要材料和能源进行综合减碳。相关结果可为公路建设项目的低碳管理及相关研究提供详实的数据支持和节能降碳措施建议。