T-Jordan Canonical Form and T-Drazin Inverse Based on the T-Product

In this paper,we investigate the tensor similarity and propose the T-Jordan canonical form and its properties.The concepts of the T-minimal polynomial and the T-characteristic polynomial are proposed.As a special case,we present properties when two tensors commute based on the tensor T-product.We prove that the Cayley-Hamilton theorem also holds for tensor cases.Then,we focus on the tensor decompositions:T-polar,T-LU,T-QR and T-Schur decompositions of tensors are obtained.When an F-square tensor is not invertible with the T-product,we study the T-group inverse and the T-Drazin inverse which can be viewed as the extension of matrix cases.The expressions of the T-group and T-Drazin inverses are given by the T-Jordan canonical form.The polynomial form of the T-Drazin inverse is also proposed.In the last part,we give the T-core-nilpotent decomposition and show that the T-index and T-Drazin inverses can be given by a limit process.

Simulation of bulk metal forming processes using one-step finite element approach based on deformation theory of plasticity

The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.

Study on Key Issues of the One-step Inverse Method

Even though the inverse method is less accurate than that of the incremental one,it has great potential in the conceptual design stage for its less calculation load and quick speed. However,it faces a number of unsolved problems,which limit its application. The first question is how to find a suitable initial solution while the other one is how to deal with the numerical problems caused by the vertical walls. In this paper,new methods have been proposed to solve above two questions. The methods have also been coded and applied to two parts to test its feasibility.

FAST ACCURATE PREDICTION OF BLANK SHAPE IN SHEET METAL FORMING

By using the Finite Element Inverse Approach based on the Hill quadratic anisotrop-ically yield criterion and the quadrilateral element, a fast analyzing software-FASTAMP for the sheet metal forming is developed. The blank shapes of three typical stampings are simulated and compared with numerical results given by the AUTOFORM software and experimental results, respectively. The comparison shows that the FASTAMP can predict blank shape and strain distribution of the stamping more precisely and quickly than those given by the traditional methods and the AUTOFORM.

Numerical solution of the imprecisely defined inverse heat conduction problem

This paper investigates the numerical solution of the uncertain inverse heat conduction problem. Uncertainties present in the system parameters are modelled through triangular convex normalized fuzzy sets. In the solution process, double parametric forms of fuzzy numbers are used with the variational iteration method （VIM）. This problem first computes the uncertain temperature distribution in the domain. Next, when the uncertain temperature measurements in the domain are known, the functions describing the uncertain temperature and heat flux on the boundary are reconstructed. Related example problems are solved using the present procedure. We have also compared the present results with those in [Inf. Sci. （2008） 178 1917] along with homotopy perturbation method （HPM） and [Int. Commun. Heat Mass Transfer （2012） 39 30] in the special cases to demonstrate the validity and applicability.

Non-exposed endoscopic wall-inversion surgery with one-step nucleic acid amplification for early gastrointestinal tumors:Personal experience and literature review

BACKGROUND Laparoscopic and endoscopic cooperative surgery is a safe,organ-sparing surgery that achieves full-thickness resection with adequate margins.Recent studies have demonstrated the safety and efficacy of these procedures.However,these techniques are limited by the exposure of the tumor and mucosa to the peritoneal cavity,which could lead to viable cancer cell seeding and the spillage of gastric juice or enteric liquids into the peritoneal cavity.Non-exposed endoscopic wallinversion surgery(NEWS)is highly accurate in determining the resection margins to prevent intraperitoneal contamination because the tumor is inverted into the visceral lumen instead of the peritoneal cavity.Accurate intraoperative assessment of the nodal status could allow stratification of the extent of resection.One-step nucleic acid amplification(OSNA)can provide a rapid method of evaluating nodal tissue,whilst nearinfrared laparoscopy together with indocyanine green can identify relevant nodal tissue intraoperatively.AIM To determine the safety and feasibility of NEWS in early gastric and colon cancers and of adding rapid intraoperative lymph node(LN)assessment with OSNA.METHODS The patient-based experiential portion of our investigations was conducted at the General and Oncological Surgery Unit of the St.Giuseppe Moscati Hospital(Avellino,Italy).Patients with early-stage gastric or colon cancer(diagnosed via endoscopy,endoscopic ultrasound,and computed tomography)were included.All lesions were treated by NEWS procedure with intraoperative OSNA assay between January 2022 and October 2022.LNs were examined intraoperatively with OSNA and postoperatively with conventional histology.We analyzed patient demographics,lesion features,histopathological diagnoses,R0 resection(negative margins)status,adverse events,and follow-up results.Data were collected prospectively and analyzed retrospectively.RESULTS A total of 10 patients(5 males and 5 females)with an average age of 70.4±4.5 years(range:62-78 years)were enrolled in this study.Five patients were diagnosed with gastric cancer.The remaining 5 patients were diagnosed with early-stage colon cancer.The mean tumor diameter was 23.8±11.6 mm(range:15-36 mm).The NEWS procedure was successful in all cases.The mean procedure time was 111.5±10.7 min(range:80-145 min).The OSNA assay revealed no LN metastases in any patients.Histologically complete resection(R0)was achieved in 9 patients(90.0%).There was no recurrence during the follow-up period.CONCLUSION NEWS combined with sentinel LN biopsy and OSNA assay is an effective and safe technique for the removal of selected early gastric and colon cancers in which it is not possible to adopt conventional endoscopic resection techniques.This procedure allows clinicians to acquire additional information on the LN status intraoperatively.

运营铁路路堑边坡病害分析与整治

针对某铁路路堑工点运营期间的挡墙开裂、侧沟变形等病害,采用了工程地质调查、勘探、室内试验等综合手段,查明了滑坡的空间形态,对病害产生的原因进行了分析,根据对比反演参数和室内试验参数确定了滑面抗剪指标,评价了工点的稳定性。按照四项病害整治原则,结合正在实施的刷方卸载应急处理措施,制定了:方案一边坡大刷方卸载+局部锚固桩+框架锚杆+仰斜排水孔;方案二边坡局部刷方卸载+抗滑桩+框架锚杆+仰斜排水孔。经过方案比选,确定采用方案一,现场实施后,整治效果良好。

基于DEFORM的索具接头内孔反挤压成形数值模拟

为研究索具接头内孔挤压成形的可行性,采用有限元方法对索具接头内孔热挤压成形工艺进行了数值模拟分析。从金属流动规律及金属的流线分布两方面分析了索具接头内孔的成形性,并研究了不同挤压条件下索具接头的应力场、应变场及成形件晶粒大小的关系。确定了热挤压工艺参数:初始挤压温度为1 100~1 150℃,挤压速度为10mm/s。通过有限元分析研究得出,内孔成形挤压后金属流线分布合理,无明显交叉、断裂的情况,且成形效果较好,尺寸精度较高。因此,该索具接头内孔热反挤压成形工艺切实可行。

Investigation of guided external inversion of thin-walled round tube

A new tube inversion method called guided tube inversion(GTI),which is based on traditional axial compression inversion,has been put forward.Computational and experimental studies of the guided external inversion of round tubes are presented.The main features of the deformation and the effects of key parameters on the forming process were discussed.Numerical and experimental results both indicated that the double-walled tubular parts made by the new method have a much higher quality than those made by traditional methods,as long as the proper parameters of the process were utilized.It was found that the die radius r,the inner diameter D of the guiding ring,the velocity V of the guiding system,and the surface friction between tube and guiding ring,play important roles in the inverting process.

TO SOLVE MATRIX EQUATION sum (A^iXBi=c) BY THE SMITH NORMAL FORM

By using the Smith normal form of polynomial matrix and algebraic methods, this paper discusses the solvability for the linear matrix equation A iXB i=C over a field, and obtains the explicit formulas of general solution or unique solution.

索穹顶比值逆迭代法形态分析

索穹顶结构的几何形状与预应力分布密切相关,在结构几何形状不变的情况下,各拉索、撑杆之间的预应力比例关系是唯一的。基于此,提出了一种新的形态分析方法——比值逆迭代法,它可以同时得到结构初始态下索杆内力分布以及平衡初始态几何,并能在迭代过程中改变结构几何使得索杆内力分布更加均匀。首先,对Gieger型索穹顶进行了形态分析,以验证比值逆迭代法的正确性,结果表明:比值逆迭代法求解效率高,得到的索杆内力分布合理,平衡初始态几何与设计初始态几何的位形偏差小。其次,在算例验证的基础上,通过在比值逆迭代法迭代过程中,根据节点位移调节撑杆下部节点的坐标,改变原算例模型的结构几何,使改进模型的内力分布更加均匀。结果表明:与原模型相比,改进模型的索杆内力分布更加均匀,且得到的平衡初始态几何满足精度要求。该算法适用于索穹顶结构的形态分析,并对结构的索杆内力分布进行了优化,为索穹顶结构的分析与设计提供了新的思路。

An engineering approach to improve the accuracy of one-step simulation for vehicle forming-to-crashworthiness integrated evaluation

To improve the accuracy of the vehicle crashworthiness simulation, it is necessary as well as important to integrate the valid forming effects of key parts. It has been agreed by many that one-step simulation results should be used only as a qualitative trend of the part but not as an engineering result for further structural analysis, especially for a relatively complex part. The study shows that it is inaccurate to analyze the forming effects with one-step simulation based on the geometry of the final part through comparison with the incremental simulation and verification with the actual part, whether in thickness or in plastic strain. However, incremental simulation is very time consuming and infeasible in the early stage of vehicle design due to lack- ing of forming tools and process parameters. An engineering approach is proposed to meet the requirement of accuracy as well as the time efficiency, where one-step simulation is conducted based on the geometry of the transformed part instead of the fi- nN part. The geometry of the transformed part is generated by simple die design engineering and proves to offer much more accuracy than the one-step simulation based on the final part geometry.

基于重力设计的可建造自由曲面建构生成研究

在形式设计阶段,运用参数化设计工具,考虑材料加工和建造施工全流程,是近年来建筑参数化设计的热点议题。本研究旨在深入探讨逆吊实验法在建筑设计领域,特别是在自由曲面结构生成方面的创新性应用。通过详细分析“登山卫海”项目的实施过程,分析如何结合Rhino建模软件的Grasshopper插件,以及NGon、Kangaroo等高级工具,实现基于力学模拟的建筑小品设计、生成与搭建。本研究不仅阐述了逆吊实验法的理论基础与实施步骤,还通过具体案例分析其在实际应用中的操作流程与实际成效,为建筑设计领域提供了新的设计思路与技术手段。

多工步板料成形问题的多步反向模拟法

提出一种新的多步反向模拟法,该方法建立在虚功原理的基础上,为提高计算精度,采用弹塑性材料模型。提出一种适用于多步反向模拟法的本构关系,可以充分考虑弹/塑性变形状态、加载/卸载状况。提出一种“双截面线法”来快速获取中间构型,可以充分考虑塑性变形对构型的影响。提出一种快速接触搜索算法来实现中间构型各个节点在约束滑移面上的移动,采用全局搜索和局部搜索策略相结合的方法,加快搜索速度。理论成果已经在自主开发的板料成形反向模拟软件InverStamp/Multi-step模块中实现。在盒形件多步拉深实例中,坯料轮廓、等效应变分布等计算结果与基于Is-dyna的增量法模拟软件Dynaform计算的结果十分吻合,验证了多步反向模拟法相比于一步反向模拟法的优势。

乍得Bongor盆地反转构造特征及形成机制分析

Bongor盆地是中—新生代陆内被动裂谷盆地,其形成和演化受周边重大构造事件的影响和控制。白垩纪早期,在非洲板块与南美板块分离、大西洋张裂的影响下,盆地开始形成并持续张裂,形成了一系列北西—南东向高角度陡立断层;白垩纪末期,在非洲板块与欧亚板块间南北向高速正向碰撞所引起的挤压应力作用下,盆地发生强烈反转,地层抬升剥蚀、褶皱变形;古近纪末受红海北西—南东向张裂产生的局部挤压应力作用,盆地发生轻微反转,部分古近系遭受剥蚀;新近纪以来盆地以稳定的热沉降为主。Bongor盆地白垩纪末期构造反转是盆地形成演化过程中的重要构造事件,深刻影响了盆地的沉积充填和油气成藏。盆内白垩纪末期构造反转以地层的褶皱变形为主要特征,根据其剖面形态可进一步分成单断型、双断型和散花型3种类型。基于最新有关断层倾角与反转应力强度的研究成果和Bongor盆地反转构造特征,认为虽然晚白垩世挤压强烈,但由于盆地断层倾角过大发生"锁死"现象,而未能发生反转。

激光半模冲击成形中板料反向变形现象研究

为了研究激光半模冲击成形在工业领域的实际应用,利用钛合金薄板作为试样进行波形零件的冲击试验,冲击过程中发现试样局部区域产生了反向变形,尤其在薄板中心区域反向变形现象更为严重。板料的反向变形使板料不能与凹模密切贴合,严重影响了冲击成形的质量。通过分析发现,由于激光能量较高,使板料与凹模凹陷处接触时的残余速度过高,从而导致板料与凹模发生剧烈碰撞。当板料因碰撞产生的反向运动速度大于板料反向屈服的速度阈值时将会产生影响成形质量的反向变形。通过调整激光能量避免了反向变形的发生,得到了理想的波形零件。实验与分析的结果表明,在满足半模冲击成形塑性变形量的基础上,采用较低的激光能量,既可避免反向变形的产生,又可保证半模冲击成形的质量。

韧性断裂准则在板料成形中应用研究进展

对板料成形中的成形极限应力图、最大变薄率、成形极限图以及韧性断裂准则等预测成形极限的方法进行了综述和分析,提出了利用韧性断裂准则能够较好地预测塑性差的板料成形极限,而且还能考虑应变路径的变化.利用有限元方法模拟时,韧性断裂准则既可以运用到完全耦合的弹塑性损伤模型的增量方法中,也可以运用到一步有限元逆算法中.指出了为准确地预测成形极限,除了提高有限元模拟精度外,应找到一种本质地反映材料性能的准则.

板料冲压成形快速分析软件FASTAMP

基于先进的有限元逆算法研制开发了具有独立版权的板料冲压成形快速分析软件FASTAMP,与传统的增量法CAE软件有很大的区别,可以进行快速的优化设计和成形性模拟,主要面向产品设计、工艺设计与模具设计人员.该软件具有一套完整的、独立的前后处理系统,其中包括标准的CAD数据接口、曲面编辑和曲面网格生成器.

中非裂谷系Bongor盆地强反转裂谷构造特征及其对油气成藏的影响

近年来，强反转裂谷盆地在油气勘探中引起越来越多的关注，中非裂谷系是强反转裂谷盆地的重要发育区。文中以Bongor盆地为例，分析了盆地的构造特征及其对油气成藏的影响，在此基础上指出勘探方向。研究表明，反转是Bongor盆地最显著的构造特征，受区域挤压应力场作用，Bongor盆地在晚白垩世和中新世发生了两期反转，特别是发生在晚白垩世桑托期（Santonian）的反转造成盆地整体大幅度抬升，地层遭受强烈剥蚀，剥蚀量达600～1 600 m，盆地剥蚀呈现出西强东弱、北强南弱的特点。反转导致残余地层发生明显的褶皱变形，并最终控制了盆地构造圈闭的成型；同时造成上成藏组合油藏的改造、破坏，使得Bongor盆地成藏模式以源内成藏为主。因此，围绕初陷期凹陷、立足下成藏组合是下步勘探的主要方向。

索结构形状确定的逆迭代法

阐述了逆迭代法的基本过程与原理,并将其运用于预应力索结构的一类形状确定问题。逆迭代法不仅能确定索结构预应力初始态的预应力分布,而且能确定索结构零状态的几何。通过算例可看出此方法的精确性与广泛适用性。