FRACTURE LIMIT LOAD OF CONE SHAPE PART IN DRAWING PROCESS

The deformation characters and load status of the blank＇s potential fracture zone are analyzed at the moment when blank is approaching to punch comer in drawing process of cone shape part. Based on tension instability theory, the formula for calculating fracture limit load of cone shape part in drawing process is derived. Also, the formula is analyzed and verified by experiment.

Explosion limits estimation and process optimization of direct propylene epoxidation with H2 and O2

Direct propylene epoxidation with H2 and O2,an attractive process to produce propylene oxide(PO),has a potential explosion danger due to the coexistence of flammable gases(i.e.,C3 H6 and H2)and oxidizer(i.e.,O2).The unknown explosion limits of the multi-component feed gas mixture make it difficult to optimize the reaction process under safe operation conditions.In this work,a distribution method is proposed and verified to be effective by comparing estimated and experimental explosion limits of more than 200 kinds of flammable gas mixture.Then,it is employed to estimate the explosion limits of the feed gas mixture,some results of which are also validated by the classic Le Chatelier’s Rule and flammable resistance method.Based on the estimated explosion limits,process optimization is carried out using commercially high and inherently safe reactant concentrations to enhance reaction performance.The promising results are directly obtained through the interface called gOPT in gPROMS only by using a simple,easy-constructed and mature packed-bed reactor,such as the PO yield of 13.3%,PO selectivity of 85.1%and outlet PO fraction of 1.8%.These results can be rationalized by indepth analyses and discussion about the effects of the decision variables on the operation safety and reaction performance.The insights revealed here could shed new light on the process development of the PO production based on the estimation of the explosion limits of the multi-component feed gas mixture containing flammable gase s,inert gas and O2,followed by process optimization.

The rate of convergence of oscillation modules for product-limit processes

Let X1,X2,…, Y1,Y2,…, T1,T2,…be independent random variables such thatXi are real-valued and have a common continuous distribution function F. Yi are extendedreal-valued and have a common distribution G and Ti are extended real-valued and have acommon distribution funtion D. The nonparametric maximum likelihood estimator of Fbased on X1,…, Xn is the empirical distribution function Fn.

THE NEAR-CRITICAL AND SUPER-CRITICAL ASYMPTOTIC BEHAVIOR IN THE THERMODYNAMIC LIMIT OF REVERSIBLE RANDOM POLYMERIZATION PROCESSES

In this paper, the near-critical and super-critical asymptotic behavior of a reversible Markov process as a chemical model for polymerization was studied. The results of the present paper, together with an analysis of the sub-critical stage, establish the existence of three distinct stages (sub-critical, near-critical and super-critical stages) of polymerization (in the thermodynamic limit as N --> +infinity,),depending on the value of strength of the fragmentation reaction. These three stages correspond to the size of the largest length of polymers of size N to be itself of order log N, Nm/m+1 (m greater than or equal to 2, m not equal 4n, n greater than or equal to 1) and N, respectively.

LIMIT THEOREMS FOR A GALTON-WATSON PROCESS IN THE I.I.D. RANDOM ENVIRONMENT

In this article, we obtain the central limit theorem and the law of the iterated logarithm for Galton-Watson processes in i.i.d, random environments.

Limit Theorems for a Storage Process with a Random Release Rule

We consider a discrete time Storage Process Xn with a simple random walk input Sn and a random release rule given by a family {Ux, x ≥ 0} of random variables whose probability laws {Ux, x ≥ 0} form a convolution semigroup of measures, that is, μx × μy = μx + y The process Xn obeys the equation: X0 = 0, U0 = 0, Xn = Sn - USn, n ≥ 1. Under mild assumptions, we prove that the processes and are simple random walks and derive a SLLN and a CLT for each of them.

带环形凸台薄盘形件旋压成形规律研究

目的探明带环形凸台薄盘形件旋压成形工艺的可行性,揭示成形过程的特点、成形缺陷的类型和产生机制,以及工艺参数对成形极限的影响规律。方法基于ABAQUS\Explicit有限元模型,分析成形过程中的材料流动、应力分布、缺陷的产生机制和工艺参数对成形极限的影响规律。结果旋压成形过程分为内槽填充、轴向隆起和径向扩展3个阶段,应力场沿径向和周向呈梯度分布,坯料在径向扩展阶段由于受压失稳产生了凸台凹坑缺陷。成形极限随凸台增厚比、盘缘宽厚比和型槽倾角的增大而增大,随旋轮进给比f的增大,成形极限先增大后减小。结论总结了增厚旋压工艺的成形特征、缺陷演化机制以及工艺参数对成形极限的影响规律,为带环形凸台薄盘形件旋压成形工艺的设计和优化提供指导。

最终接头临时锚拉系统设计及工艺研究

“整体预制水下推出式”最终接头结构设计复杂,安装精度要求高,施工风险大。为有效保证最终接头水下施工过程安全可控,保证最终接头及其两侧已安装沉管施工质量,通过安装特定结构的临时锚拉系统,抵消水力压接过程中GINA止水带反弹作用力。根据其工作原理及受力特点,结合有关资料进一步研究、制定了大应力作用下限位刚拉杆拆除方案,确保最终接头施工顺利实现提供必要基础。通过现场实践,该系统及工艺可在类似工程中参考应用。

An Example of Machine Vision Applied in Printing Quality Checking——Research on the Checking of Printing Quality by Image Processing

The traditional printing checking method always uses printing control strips,but the results are not very well in repeatability and stability. In this paper,the checking methods for printing quality basing on image are taken as research objects. On the base of the traditional checking methods of printing quality,combining the method and theory of digital image processing with printing theory in the new domain of image quality checking,it constitute the checking system of printing quality by image processing,and expound the theory design and the model of this system. This is an application of machine vision. It uses the high resolution industrial CCD(Charge Coupled Device) colorful camera. It can display the real-time photographs on the monitor,and input the video signal to the image gathering card,and then the image data transmits through the computer PCI bus to the memory. At the same time,the system carries on processing and data analysis. This method is proved by experiments. The experiments are mainly about the data conversion of image and ink limit show of printing.

高炉热风炉增设烟气净化系统能耗分析

为了满足钢铁焦化行业排放限值要求,山西太钢不锈钢股份有限公司六高炉热风炉新建设一套处理量50万m^(3)/h的烟气净化系统装置进行脱硫处理,对该项目主要用能工艺进行能耗分析。实践表明,该项目符合《中国节能技术政策大纲》合理用能标准和节能设计规范的要求。

不同灭菌工艺对生川乌中乌头类双酯型生物碱成分及产品质量影响研究

目的:在保证生川乌药效的前提下,筛选最优灭菌工艺。方法:分别采用热压灭菌、干热灭菌、钴-60辐照灭菌三种方法进行灭菌处理,采用HPLC法考察灭菌后乌头类双酯型生物碱含量变化情况,同步考察药材及其产品微生物数量是否符合标准,以综合评估大生产适用工艺。结果:3种灭菌方法均能使产品符合成品质量标准,综合考虑灭菌后样品微生物数量、指标成分含量、效率等因素,干热灭菌工艺是最优工艺。结论:在干热灭菌条件下,产品微生物限度符合要求,乌头类双酯型生物碱转移率较优,生产效率可接受,可作为工业生产最优工艺。

限位支架级进冲压模具设计

根据制件的结构、材料和精度对其进行冲压工艺性能分析,确定该制件包括落料、冲孔、翻边三个基本工序。提出三种不同的冲压方案,综合考虑生产批量、成本、模具数量、操作安全性等方面因素,确定选用级进模冲压方案。提出两种不同排样设计方案,综合考虑零件结构特点和材料利用率,确定选用竖排排样方案。在此基础上,完成了必要的工艺计算、结构设计和标准件的选型。应用结果表明:采用多工位级进模完成限位支架的冲压加工,可满足大批量、高安全性及成本相对较低的生产要求。

侧围外板腰线后三角窗位置起皱分析及对策

从冲压成型理论出发,结合成型极限图(FLD)阐述冲压起皱机理,为分析起皱问题提供了思路,以某车型SUV侧围外板为例,对腰线后三角窗位置的起皱问题进行解析,并于同步工程阶段,借助AutoForm分析软件找到了一种解决该起皱问题的对策,产品实物证实了该方法的有效性,对于同类结构的产品或工艺提供了参考,具有一定的推广和借鉴意义。

荆芥穗总黄酮提取工艺优化及含量测定研究

目的研究荆芥穗药材中总黄酮的最佳提取工艺,进而利用优化的提取工艺提取、测定荆芥穗药材中总黄酮的含量,为完善荆芥穗药材的质量标准提供科学依据。方法以总黄酮含量为评价指标,乙醇浓度、浸提时间和浸提温度为考察因素进行单因素试验,得出每个因素的3个较优水平,在此基础上,设计3因素3水平L9(34)正交试验,并进行直观分析和方差分析,得出最优提取工艺,最后以最优提取工艺对10批荆芥穗药材的总黄酮进行提取、含量测定。结果荆芥穗总黄酮的最优提取工艺为乙醇浓度60%、浸提时间20 min、浸提温度80℃。10批荆芥穗药材中总黄酮的平均含量为5.82 mg·g^(-1)。结论通过单因素和正交设计试验优化了荆芥穗总黄酮的提取工艺,并测定分析了10批荆芥穗药材的总黄酮含量,初步拟定荆芥穗药材总黄酮含量的限度标准为不得少于4.0 mg·g^(-1)。

苏州特别排放限值下城镇污水处理厂提标改造成效分析

为适应我国经济社会与生态环境形势的巨大变化,苏州市于2018年提出“苏州特别排放限值”。截至2020年底,苏州全市城镇污水处理厂均已完成提标改造工作。本研究根据苏州市80座城镇污水处理厂提标改造前后运行情况,通过研究处理规模、负荷率和出水水质等变化,分析本轮提标改造成效。结果表明,经本轮提标改造后,苏州市80座城镇污水处理厂总处理能力提升25.34%且负荷率分布趋于集中;化学需氧量、氨氮、总磷和总氮平均出水浓度分别下降19.81%、48.82%、34.47%和24.72%,平均去除率分别提高1.82%、1.43%、1.24%和9.48%,出水水质基本满足“苏州特别排放限值”要求;工程型与管理型提标改造措施均具有较好的成效。

输入受限的二阶非仿射非线性不确定系统串级自耦PID控制

针对一类输入受限的二阶非仿射非线性不确定系统的控制问题,提出了一种串级自耦PID控制方法。在考虑了系统输入饱和受限的前提下,将二阶系统分为外环广义位移环和内环广义速度环,分别采用自耦PD和自耦PI算法实现串级控制策略。解决了自耦PID控制面对输入信号为阶跃信号时需要设计过渡过程的短板;设计了串级耦合速度因子,并将内外环的可调参数进行了数据拟合,进一步降低了控制器的调参难度,分析并证明了串级自耦PID控制的合理性和稳定性。仿真结果表明,所提控制方法较自耦PID控制不仅响应速度快、鲁棒性更好,而且具有极强的抗干扰能力,在一类二阶非仿射非线性不确定系统的控制领域具有广泛的应用前景。

小米醋博物馆砖穹顶结构设计

山东省淄博市小米醋博物馆的入口大厅采用了砖穹顶结构。利用有限元分析软件对砖穹顶结构进行计算,对不同母线形状的结构方案进行了比选,分析了结构底部设置的3处拱形门洞对结构内力的影响,并采用极限平衡法对结构进行校核,得出了穹顶结构的主要自振模态以及在地震作用下的动力特性。对结构在不同施工阶段的受力进行了分析,建立了精确的砌砖模型,对整个施工过程进行指导和把控。详细介绍了穹顶结构的排砖方式,对传统砌砖工艺进行了改良,以达到结构受力与建筑美观的巧妙结合。结果表明:静力作用下结构底部的门洞顶出现拉应力集中,各门洞顶之间形成了环向拉应力;地震作用下结构中部以及未开洞一侧底部的拉应力值较小且分布均匀,靠近门洞底部的结构拉应力显著增大。

Lagrangian simulation of multi-step and rate-limited chemical reactions in multi-dimensional porous media

Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge traditional modeling approaches. The kinetics of chemical reactions in groundwater are well known to be controlled by medium heterogeneity and reactant mixing, motivating the development of particle-based Lagrangian approaches. Previous Lagrangian solvers have been limited to fundamental bimolecular reactions in typically one-dimensional porous media. In contrast to other existing studies, this study developed a fully Lagrangian framework, which was used to simulate diffusion-controlled, multi-step reactions in one-, two-, and three-dimensional porous media. The interaction radius of a reactant molecule, which controls the probability of reaction, was derived by the agent-based approach for both irreversible and reversible reactions. A flexible particle tracking scheme was then developed to build trajectories for particles undergoing mixing-limited, multi-step reactions. The simulated particle dynamics were checked against the kinetics for diffusion-controlled reactions and thermodynamic wellmixed reactions in one-and two-dimensional domains. Applicability of the novel simulator was further tested by(1) simulating precipitation of calcium carbonate minerals in a two-dimensional medium, and(2) quantifying multi-step chemical reactions observed in the laboratory. The flexibility of the Lagrangian simulator allows further refinement to capture complex transport affecting chemical mixing and hence reactions.

SUBCRITICAL ASYMPTOTIC BEHAVIOR IN THE MODIFIED LUSHNIKOV PROCESS OF POLYMERIZATION

We consider a modified Lnshnikov process as a model of a chemical polymer ization anf study the asymptotic behavior (in the thermodynamic limit;as N →∞)of a particular probability distribution on the set of N-dimensional vectors,tile kth component of which is the number of k-mers.The study study establisles the existence of three stages (subcritical,near-critical and supercritical stages)of polymerization,dependenting upon the ratio of association and dissociation rates of f polymers.The present paper concentrates on the analysis of tile subcritical stage.In the sibcritical.stages we show that tile size of the largest length of polymers of stize N is of the order.log N as N →+∞.

Momnts and limiting distribution of a portfolio of whole life annuity pollcies

A dual random model of a portfolio of variable amount whole life anunity is set with the mth moment of the present value of benefits.and the respective expressions of the monments under the assumption that the force of interest accumulation fuction is Wiener process of Omstein-Uhlenbeck process,Furthermore,the limiting dstribution of average cost of this protfolio is discussed with the expression of the limiting distribution under the assumption that the force of interest accumulation is an independent increment process.