基于逆向工程的产品设计研究

工程生产中的产品设计一般采用正向工程设计,主要根据产品的功能与用途提出构想思路,借助计算机三维软件建模,最后通过技术手段加工成型。针对其设计方法存在的设计周期较长问题,提出一种逆向工程设计思维并通过鞋底的逆向工程设计实验进行验证。首先针对鞋底的结构进行研究分析,并用三维扫描设备获取实物模型表面的点云数据,并在geomagic studio软件平台上处理点云数据得到目标曲面的NURBS曲面数据,然后利用geomagic studio软件与UG软件的交互功能将数据导入到UG中进行正向建模工作,在正向建模过程中借助软件对其结构进行分析并对存在的问题进行结构优化处理,实现逆向工程设计模仿之外的再创新意图,最终利用3D打印技术得到升级产品的实物模型。通过实例的结果证明,混合建模的设计方法能在保证产品质量的条件下可尽量缩短设计周期,降低研发成本。     

基于NURBS的自由曲面在陶瓷造型设计中的实践性研究

NURBS功能可帮助在计算机中表达设计思维与创意,实现陶瓷的三维造型。本文主要在探讨NURBS曲面造型方法的基础上,研究如何通过计算机对陶瓷的造型进行辅助设计,同时对陶瓷造型中的曲面形态加以关注,以实际应用案例作为参照和类比。     

基于MATLAB的精馏设计型计算

精馏设计型计算具有计算量大、算法复杂等特点。利用Matlab平台，开发了双组分精馏设计型计算程序。应用结果表明，此程序具有一定的通用性，可应用于部分双组分理想物系。     

大型风电叶片模具型面控制研究

随着风电产业的发展,风电叶片已由原来的kW级发展到现在的6MW级,甚至更大。风电叶片模具一直采用玻璃钢复合材料,成型工艺采用真空灌注成型。模具长度由最初的10m发展到现在的60m,甚至更长,其型面精度变得愈加难以控制。风力发电的效率高低直接取决于叶片翼形的准确,这就需要叶片模具的型面尺寸与设计值具有较高的吻合度。因此,本文开展了大型风电叶片模具型面精度控制等相关研究。     

基于逆向工程的风机叶片数控加工

本文以曲面复杂的风机叶片为研究对象,采用逆向工程技术,利用接触式三坐标测量仪对风机叶片数据进行采集处理,通过点云数据测量、预处理、自由曲面重构等技术,进行风机叶片实体模型生成及数控模拟仿真,为风机叶片的高效生产奠定了基础,具有一定的应用价值和实际意义。     

基于逆向工程技术的鼠标壳造型设计

逆向工程是一种全新设计与制造技术,采用逆向方法进行产品造型设计和模具开发,是缩短产品开发周期,提高产品质量,进而建立自己的设计制造体系的重要手段。本文以了鼠标壳配合件为例,介绍了逆向工程技术3D造型的一般步骤和方法     

啮合型连续混炼机转子流场分析与转子几何造型的理论研究

建立啮合连续混炼机转子的三维非牛顿等温流场模型，并进行流场分析。利用ANSYS软件进行数值模拟，得到流场的压力场、速度场和粘度场，用自编程序对转子流场中的回流量、越过转子棱的流量和平均剪切应力进行了计算，并对转子的几何参数对转子的流场混炼效果的影响进行讨论。     

同向双螺杆几何设计计算软件的应用

通过算例介绍了同向双螺杆几何设计计算软件的功能。该软件除构造元件几何形状及间隙修正外,将同一双螺杆上所有规格的螺杆元件作为一个整体进行综合设计计算,以保证各元件之间的平滑接合。由此提出端面接合误差修正的问题以及捏合盘设计计算的新方法。可根据不同需要计算轴截面、横截面及斜截面中螺杆元件曲线的坐标值,并以数据库的形式存储。该软件所具备的功能是双螺杆CAD/CAM的基础。     

基于逆向工程的塑料产品快速开发方案

详细介绍了曲面重构的3种主要方案：①以B-Spline为基础的重构;②以三角Bezier为基础的重构;③以扫描点直接产生曲面.刘样件进行曲面重构后,还需进行三维建模,才能进行改型设计和尺寸修改.将完成的CAD模型导入CAE软件中进行有限元分析,再优化CAD模型,之后通过快速原型设备完成样件制造.实践证明此快速开发方案可缩短开发周期.     

基于STL模型的逆向工程实体建模技术

针对以STL数据表示的零件模型，在分析结构件模型几何特点的基础上，提出了一种以几何体素分离与拓扑关系重建为基础的STL模型逆向工程实体建模技术。通过对三角面片的合并实现平面、柱面、锥面等基本几何体素的分离，并利用Parasolid系统完成体素重构，进一步提取几何体素之间的布尔关系，从而实现含拓扑关系的产品模型重构。利用这一方法，可以实现RE／RP系统与通用CAD系统之间的快速集成，实现产品数据在不同系统之间顺畅传递。     

逆向工程技术在汽车后视镜设计中的应用

介绍了逆向工程技术及其工作过程,包括数字化处理、三维建模、加工制造、测量检验等阶段,以汽车后视镜为例,重点介绍了其数字化处理和建模。     

A model of the infrared cure of powder coatings based on surface absorptivities in-situ measurements

The efficiency of radiative powder coatings curing depends both on the coating radiative properties and the spectral emissivities of the infrared emitters. This investigation is structured to develop a mathematical model using the radiative properties of the coating to describe precisely the coating temperature and deduce the degree of polymerization conversion during the cure. The reflectance measurements results obtained with a FTIR equipped with an integrating sphere are analyzed and implemented in a thermal model. These results show that reflectance values vary with the chemical composition, the pigment nature, and are influenced by the powder coatings cure. The thermal model, solved with the finite volume method, permits to compute the varying temperature within the thickness of the powder-coated metal sample and provides a good prediction of the temperature within the “coating + substrate” system. The experimental cure of powder coatings supporting this study was performed in a small test oven equipped with electrical infrared emitters. Presented at 2006 FutureCoat! Conference, sponsored by Federation of Societies for Coatings Technology, November 1–3, 2006, in New Orleans, LA.     

基于吸附-扩散模型和遗传算法的反渗透膜性能预测

基于反渗透膜的吸附-扩散模型,导出了多孔膜对溶质的浓缩比表达式和组件的溶质平均脱除率。采用遗传算法对膜的性能进行了数学模拟,计算出了氯化钠对ESPA2反渗透膜的膜相溶质分配系数、溶质的膜相扩散系数、溶剂(水)的膜相扩散系数、膜的孔隙率和膜分离层厚度,计算得到的膜分离层厚度和膜相中水扩散系数等参数与芳香聚酰胺复合膜的测定值相吻合,其中,氯化钠透过率的均方差在10-7～10-6之间。     

Control strategies for intermittently mixed, forcefully aerated solid-state fermentation bioreactors based on the analysis of a distributed parameter model

This paper tests different control strategies based on classic proportional integral derivative (PID) and advanced dynamic matrix control (DMC) algorithms for an intermittently stirred, forcefully aerated solid-state fermentation bioreactor. The study was done using a distributed parameter model to reproduce the main operating features of this type of bioreactor. There is predicted to be a remarkable improvement in the bioreactor productivity when control strategies are implemented. For this type of bioreactor, the temperature and water content of the substrate bed can be controlled by saturating the air at the air inlet but manipulating its temperature, coupled with a strategy of water replenishment when the water content of the bed falls below a threshold. Dynamic matrix control is superior to PID control; however, a specific convolution matrix for different stages of the fermentation is necessary due to the changing behavior of the system. This work shows the benefit of mathematical modeling, since the many different operating conditions investigated via simulations would not have been economically feasible to undertake experimentally with a large-scale bioreactor. The results obtained provide an excellent starting point for such large-scale experimental work.     

Molecular modeling of cellulose in amorphous state. Part I: model building and plastic deformation study

Molecular modeling was utilized to provide insight into the yielding behavior and poor recovery from applied strain for cellulose. Amorphous cellulose models were successfully built and examined with the use of force field pcff_300_1.01. High-temperature molecular dynamics, followed by minimization, was used to generate relaxed structures for amorphous cellulose. Properties related to inter-molecular interactions were calculated for these models and found to be comparable with literature values. The observed yielding for these models, which occurred at approximately 7-8% strain, was found to be due to the disruption of hydrogen bonds between cellulose chain segments. New hydrogen bonds were formed in extension but only 1/3 of these were broken during recovery. These newly formed hydrogen bonds were found to hold the cellulose chain segments in the new positions thus resulting in poor deformation recovery.     

Effects of laser polishing on surface quality and mechanical properties of PLA parts built by fused deposition modeling

Fused deposition modeling (FDM) produces parts through layer by layer on the top of each other, making it almost impossible to obtain smooth printed parts. Hence, there is a huge demand for the postprocessing of the FDM-printed parts. Laser polishing is a novel technique that can be used to polish products to obtain a smoother surface. The aim of this work was to explore the feasibility of surface-finishing FDM-printed polylactic acid (PLA) parts by laser polishing. The surface roughness, surface morphology, dynamic mechanical analysis (DMA), and tensile properties were investigated. The results indicated that the lower laser power and the bigger laser beam diameter within a certain range could facilitate the formation of smoother surface. With optimized parameters, the surface roughness was reduced by 90.4%. DMA showed that the storage modulus (E’) and glass transition temperature of PLA specimens were significantly improved due to the decrease of molecular mobility of denser structures. Moreover, the tensile strength and Young's modulus of the PLA specimen were also significantly increased after laser polishing. The fracture morphologies were observed, and the possible strengthening mechanism was also discussed. These results indicated that laser polishing could be an efficient method for surface polishing of FDM parts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48288.     

基于气液界面能量模型的冷凝不稳定性分析

建立了管道内冷凝诱发的段塞流生成与演化动力学模型。在分析前人的研究成果基础上考虑传热的因素,预测了冷凝流动过程中分层流向段塞流等不稳定流型转化的界限,在预测过程中将光滑分层流模型和从能量角度考虑的界面模型联合起来求解流动过程中的截面含气率,并将结果同前人(Cavallini,2003)使用实验关联式求解截面含气率来分析分层流不稳定性模型的结果进行了比较。研究结果表明:新建立的模型在较大管径下,干度x0.25时,模型与Cavallini(2003)的模型较吻合;同时,选取不同的质量流速初值qm对建立的模型的计算结果的影响可以忽略不计。     

An extracellular stochastic model of early HIV infection and the formulation of optimal treatment policy

The problem of scheduling optimal treatment strategies for patients at the early stage of human immunodeficiency virus (HIV) infection is investigated. Unlike patients with an established HIV infection, complete eradication of the infection is still possible at this stage and treatment can further increase the probability of eradication. However, high dosages of drugs should be avoided, if possible, because of toxic side effects. Stochastic simulation is capable of determining the infection establishment probability at the early infection stage. Consequently, to obtain acceptable treatment strategies, an optimization problem was formulated, employing a stochastic model to predict the response of an average patient to treatment. Optimal treatment strategies for prompt and also a few days latency in treatment initiation were computed. These strategies were compared with constant treatment strategies and were shown to be more beneficial in silico, i.e., they either decreased the infection establishment probability or the dosage of the drugs.     

以Guglielmi模型研究脉冲电流下Ni-SiC复合电沉积

在Guglielmi模型的基础上,推导了采用方形、上三角形、下三角形和锲形四类脉冲波形复合电沉积时,电流与镀层中惰性微粒体积分数的数学关系,并以Ni–SiC复合电沉积为例,进行了试验验证。结果表明,在相同峰值电流密度下,方波脉冲电流下SiC的沉积量是其他三类脉冲电流波形的1.51倍;而当平均电流密度相同时,方波脉冲电流下SiC的沉积量是其他三类电流波形的1.06倍。分析了电流密度对镍基体上SiC沉积量的影响。     

响应曲面法优化碳酸锂反应结晶工艺

碳酸锂是制备各种锂化合物的基础锂盐,碳酸锂的制备是锂产业链当中的承前启后的关键技术。以察尔汗盐湖老卤为原料,采用响应曲面法中的central composite design（CCD）设计实验,分别考察了温度、碳酸钠加料速度、碳酸钠浓度和锂离子浓度4个因素及交互作用对反应结晶工艺中碳酸锂的收率和粒度的影响,并分别建立了响应值与影响因素之间的回归方程。响应预测最佳值为：碳酸锂收率93.68%、粒径（d₅₀）16.73 μm;相应的实验值分别为94.01%和16.91 μm。预测值与实验值接近,误差较小,说明响应曲面法建立的预测碳酸锂反应结晶的模型可靠,在最佳工艺条件下分析所制得的产品,用ICP-AES分析纯度为99.52%,用XRD分析基本无杂峰,说明反应结晶生成Li₂CO₃晶体,其主要晶面为（-1 1 0）、（-2 2 0）和（0 0 2）。