Simulation-Based Construction of Three-Dimensional Process Model for Punching Cartridge Cases

A method of constructing three-dimensional process model for the punching cartridge cases is presented based on DEFORM simulation analysis. Using DEFORM software,the finite element simulation models for the punching and forming process of cartridge cases are established,and the corresponding simulation result model of each intermediate procedure is obtained by continuously performing the forming process simulation. The simulation model cannot annotate size and process information due to poor interface between DEFORM software and CAD software. Thus,a 3D annotation module is developed with secondary development technology of UG NX software. Consequently,the final process model with dimension and process information is obtained. Then,with the current 3D process management system,the 3D punching and forming process design of cartridge cases can be completed further. An example is also provided to illustrate that the relative error between the simulation process model and the physical model is less than 2%,which proves the validity and reliability of the proposed method in this study.

SMALL DENSITY FLUCTUTAION FOR ONE DIMENSIONAL CONTACT PROCESSES UNDER NONEQUILIBRIUM

This paper shows that for a supercritical contact process in one dimension, if the initial distribution satisfies reasonable hypothesis, then the first hitting time of certain set with anomalous small density is asymptotically exponentially distributed. We also show the similar result for the contact process on the finite set [0, N].

Effect of Processing Conditions on the Compression Elasticity of Three Dimensional Crimp Staple

The multi-hollow three dimensional(3-D)crimp sta-ple were prepared by the non-symmetrical cooling spin-ning technology.The material properties,spinneret shape,drawing conditions,heat-setting conditions and silicon finishing conditions that influence the compression elasticity of the staple have been investigated.It is found that the compression elasticity of 3-D crimp PET staple is larger than that of 3-D crimp PP staple.The com-pression elasticity of the 5-hollow staple is much

Description and reconstruction of one-dimensional photonic crystal by digital signal processing theory

A method of describing one-dimensional photonic crystals （1DPCs） based on Z-domain digital signal processing theory is presented. The analytical expression of the target band gap spectrum in the digital domain is obtained by the autocorrelation of its impulse response. The feasibility of this method is verified by reconstructing two simple 1DPC structures with a target photonic band gap obtained by the traditional transfer matrix method. This method provides an effective approach to function-guided designs of interference-based band gap structures for photonic applications.

COMPUTER SIMULATION OF 3-DIMENSIONAL DYNAMIC ASSEMBLY PROCESS OF MECHANICAL ROTATIONAL BODY

Focusing on the study of the components of mechanical rotational body,the data structure and algorithm of component model generation are discussed.Some problems in assembly process of 3 dimensional graph of components are studied in great detail.

基于Point Transformer方法的鱼类三维点云模型分类

为实现对不同鱼类的精准分类,研究共采集110尾真实鱼类的三维模型,对获取的3D模型进行基于预处理、旋转增强和下采样等操作后,获取了1650尾实验样本。然后基于Point Transformer网络和2个三维分类的对比网络进行数据集的分类训练和验证。结果表明,利用本实验的目标方法Point Transformer获得了比2个对比网络更好的分类结果,整体的分类准确率能够达到91.9%。同时对所使用的三维分类网络进行有效性评估,3个模型对于5种真实鱼类模型的分类是有意义的,其中Point Transformer的模型ROC曲线准确率最高,AUC面积最大,对于三维鱼类数据集的分类最为有效。研究提供了一种可以实现对鱼类三维模型进行精准分类的方法,为以后的智能化渔业资源监测提供一种新的技术手段。

固体姿轨控发动机变工况过程推力不确定性分析

为探究喉栓式固体姿轨控发动机推力动态性能可靠性,考虑燃气阀几何参数不确定性对固体姿轨控发动机变工况过程推力性能不确定性开展研究。结合固体姿轨控发动机工作原理、推力数学模型和零维内弹道方程构建发动机变工况过程推力计算模型。在此基础上,根据固体姿轨控发动机阀门几何参数不确定性模型,采用蒙特卡罗模拟法进行不确定性传递,获取喉栓瞬时运动后推力不确定性随时间的变化规律,实现变工况过程推力不确定性分析,并对不确定性变量进行重要度排序。量化评估固体姿轨控发动机实时调节过程中的推力不确定性,可以为固体姿轨控发动机控制系统提供更合理的设计要求,在满足设计需求的同时节省研制成本。

一种优化深度域速度反演的方法

山前带地震资料信噪比低,剩余速度场拾取困难,深度域速度场难以迭代收敛到最优,是山前带地震资料无法实现偏移准确归位的主要原因。利用五维数据规则化中的数据插值技术对偏移前的原始共中心点道集进行数据重构,通过改变观测系统,改善其面元属性,提高地震资料信噪比,以满足叠前深度偏移速度场迭代的需求。同时为了保证偏移数据的保真性,数据插值得到的高信噪比共中心点道集仅作为深度域速度场迭代反演的输入道集,原始共中心点道集作为最终叠前深度偏移成像的输入道集,在此基础上,实现了深度域速度场迭代的快速准确收敛。实际资料应用表明,该方法可行性强,迭代更新求取的最终偏移速度场准确,偏移剖面反射归位合理,可为山前带叠前深度偏移速度建模提供借鉴。

功率超声对无掩膜定域性电沉积三维镍质微结构成型过程的影响

提高高深宽比三维金属微结构成型精度一直是微电子信息制造、MEMS等领域的研究重点。以制备直径为60μm、长径比为8∶1的微镍柱为例,在无掩膜定域性电沉积(MLED)微镍柱过程中,施加一定强度、与电场作用方向相同的功率超声波,探讨超声波对无掩膜定域性电沉积三维镍质微结构成型过程的影响。主要开展了无功率超声作用及有功率超声作用下MLED制备微镍柱过程中平均体积沉积速率、表面形貌及晶粒尺寸的对比研究。结果表明:相较于无功率超声作用,有功率超声作用下MLED的平均体积沉积速率可提高28%~39%,最高平均体积沉积速率可达15340.46μm^(3)/s;功率超声作用可进一步细化沉积体的晶粒尺寸,平均晶粒尺寸可达46.37 nm;同时,功率超声作用可在一定程度上改善MLED微镍柱的微观表面形貌。

基于IAHP-CRITIC二维云模型的舰船电力系统韧性评价

舰船电力系统是舰船正常运行的关键,具有高度的复杂性和模糊性,导致难以对其韧性做出准确、客观地评价。对此,基于对舰船电力系统主要任务的分析,对舰船电力系统韧性评价指标体系进行构建,采用区间层次分析法(interval analytic hierarchy process,IAHP)和层间相关性准则重要性法(criteria importance though intercrieria correlation,CRITIC)分别求解评价指标体系的主、客观权重,并运用改进博弈论方法确定组合权重,降低权重计算的主观性和随机性。结合二维云模型从防御能力和恢复能力两个维度对舰船电力系统韧性进行评价,更为全面、客观地反映舰船电力系统韧性。示例表明,所提方法能够有效解决舰船电力系统韧性评价中的随机性和不确定性问题,有利于得到更为准确、客观的评价结果。

基于机器学习的我国天然气进口量预测及其运输安全评价

天然气作为一种高效、低碳、清洁的化石能源,具有易存储、运输和储量丰富的特性,被视为其他化石能源的最佳替代品之一。在确保我国天然气供应的连续性及实现碳达峰与碳中和目标的过程中,准确预测我国天然气进口量并对其运输安全进行评价显得尤为关键。针对单一特征选择方法特征筛选结果不稳定的问题,本文提出了一种基于多属性决策的特征选择方法,并根据特征选择结果建立高斯过程回归模型对我国天然气进口量进行预测。同时,提出了一种结合熵权与t-SNE降维的K均值聚类模型,并将其应用于评估我国天然气进口运输安全。结果表明:本文所提出的基于多属性决策的特征选择方法所得到的特征重要程度排序更加稳定,对我国天然气进口量影响最大的3个指标分别是:能源消费总量中天然气占比、居民消费水平和国内天然气管道长度;高斯过程回归模型对我国天然气进口量预测的绝对百分比误差均在5%以下,预测精度高;与传统t-SNE降维相比,结合熵权的t-SNE降维方法具有更低的KL散度,其降维结果更贴近原始数据的分布;结合熵权与t-SNE降维的K均值聚类结果可信度更高,我国进口天然气运输安全状态越来越好,并且对其影响最大的3个指标分别是:自有船队运力供给、管道气年运输量和LNG年运输量。

大尺寸直拉硅单晶生长的多物理场建模与优化

随着光伏和半导体行业的快速发展,制备更大直径(12英寸及以上,1英寸=2.54 cm)的硅单晶成为趋势,直拉法作为硅单晶最主要的制备方法备受重视。然而在制备大直径和高质量的直拉硅单晶的过程中,随着晶体直径和坩埚尺寸的增加,熔体体积显著增加,热场、流场及应力场的复杂性显著提升,涡流、热浮力和科里奥利力的相互作用会造成熔体流动的强烈湍流和速度、温度波动,出现诸如固液界面温度分布不均,熔体内热对流复杂等问题,从而影响硅单晶中的缺陷分布。因此,如何实现对工艺参数的控制,以获得理想的大直径硅晶体具有重要的研究意义。本文针对实际生产的滞后性和成本问题,建立了可以实时预测、动态控制和优化工艺参数的40英寸热场制备18英寸硅单晶棒的二维轴对称全局数值模拟模型,考虑了坩埚深度及热传导路径的延长,在主加热器的基础上,增加底部加热器,采用有限元法逐一分析晶体转速、坩埚转速、气体压强的变化对单晶硅热场和硅晶体生长的影响,包括固液界面形状、温度梯度、V/G值、氧浓度及缺陷分布等。通过多次仿真实验,获得了一组较为合适的工艺参数组合:晶体转速15 r/min、坩埚转速5 r/min、炉内气压1200 Pa,可使固液界面温度梯度较小,且温度分布更加均匀,有效避免了过度湍流化。进一步采用制备18英寸硅单晶棒的验证实验及性能检测发现,采用仿真所得最优工艺参数组合生产的硅单晶棒能将成晶率提升至87.44%。这组针对18英寸硅单晶棒的最佳工艺参数组合(包括晶体转速、坩埚转速及炉内气压等)经过精细优化,主要基于大尺寸(12英寸及以上)直拉硅单晶生长过程中热场和流场的复杂性,对大尺寸硅单晶具有较好的适应性,但在更小尺寸(如4、6或8英寸)的硅单晶生长中,由于热传递和气流扰动的不同,最佳工艺参数组合可以作为参考,但还需要进行具体条件下的验证和调整。本研究建立的数字化模型能够准确预测并优化大尺寸直拉硅单晶的生长过程,提质降本,具有实际应用前景。

Influence of Processing Parameters on Granularity Distribution of Superalloy Powders during PREP

In order to investigate the influence of processing parameters on the granularity distribution of superalloy powders during the atomization of plasma rotating electrode processing (PREP), in this paper FGH95 superalloy powders is prepared under different processing conditions by PREP and the influence of PREP processing parameters on the granularity distribution of FGH95 superalloy powders is discussed based on fractal geometry theory. The results show that with the increase of rotating velocity of the self-consuming electrode, the fractal dimension of the granularity distribution increases linearly, which results in the increase of the proportion of smaller powders. The change of interval between plasma gun and the self-consuming electrode has a little effect on the granularity distribution, also the fractal dimension of the granularity distribution changed a little correspondingly.

矿用皮带机防纵向撕裂保护装置的设计

提出一种通过三维(3D)点云处理识别纵向撕裂的方法,即通过双目线激光立体视觉相机获取皮带表面的空间点数据,在这些数据中,由裂痕和划痕引起的疑似点被提取出来;随后采用聚类和判别机制来区分撕裂和划痕,并仅以撕裂信息作为报警标准;最后使用主成分分析(PCA)方法可以在三维空间中有效地表征裂痕的方向和最大宽度。应用该方法可以为纵裂等类似缺陷的识别场景提供更有效、更合适的解决方案。

多孔氮化碳的制备及其在织物柔顺护理的应用

首次研究了一种多孔氮化碳作为织物柔顺剂,以双氰胺作为氮化碳基础构架,通过硫脲作为致孔剂,得到具有多孔结构的堆叠氮化碳,可有效吸附在织物的纤维表面,通过其超薄的二维纳米大片层,对织物起到有效的润滑作用,平顺毛躁。使用扫描电子显微镜表征了氮化碳的微观孔隙结构,使用X射线衍射和X射线光电子能谱表征确认了氮化碳的基本理化性能。对氮化碳的粒径分析表明,接近493.7 nm的平均粒径的叠层氮化碳具有最佳的柔顺效果。氮化碳作为单一的柔顺剂可以使柔顺护理过后的织物手感顺滑、蓬松,抗静电性提升。多孔氮化碳和其他柔顺成分复配,或者直接加入到市售的成品柔顺剂中,都能对柔顺效果有较好的提升。多孔氮化碳具有良好的化学稳定性,可以与各种体系兼容。首次采用纳米级的多孔氮化碳用于织物的柔顺护理,为纳米材料用于织物整理提供了新的应用方向。

Locating Error Considering Dimensional Errors Modeling for Multistation Manufacturing System

Multistation machining process is widely applied in contemporary manufacturing environment. Modeling of variation propagation in multistation machining process is one of the most important research scenarios. Due to the existence of multiple variation streams, it is challenging to model and analyze variation propagation in a multi-station system. Current approaches to error modeling for multistation machining process are not explicit enough for error control and ensuring final product quality. In this paper, a mathematic model to depict the part dimensional variation of the complex multistation manufacturing process is formulated. A linear state space dimensional error propagation equation is established through kinematics analysis of the influence of locating parameter variations and locating datum variations on dimensional errors, so the dimensional error accumulation and transformation within the multistation process are quantitatively described. A systematic procedure to build the model is presented, which enhances the way to determine the variation sources in complex machining systems. A simple two-dimensional example is used to illustrate the proposed procedures. Finally, an industrial case of multistation machining part in a manufacturing shop is given to testify the validation and practicability of the method. The proposed analytical model is essential to quality control and improvement for multistation systems in machining quality forecasting and design optimization.

数字孪生技术下电网设备质量检测方法研究

电网设备结构复杂且处于高压电网运行环境中,受光照、高温等因素影响,会导致以人工为基础的电网设备质量检测存在效果不佳、自动性差等问题。为此,提出数字孪生技术下电网设备质量检测方法。采用数字孪生技术建立电网设备虚拟三维模型,实现物理空间到虚拟数据的映射。通过改进粗糙K均值算法对电网设备虚拟三维模型中的电网设备数据聚类,以获取电网设备特征参数。基于电网设备状态质量指数和未来状态质量指数完成电网设备质量自动检测。试验结果表明,所提方法的电网设备质量自动检测精度高、数据聚类时间短,而故障检测精度高达97%。该研究为实现电力数据挖掘提供了技术支持。

Surface Rainfall Processes during the Genesis Period of Tropical Cyclone Durian(2001)

The rainfall processes during the formation of tropical cyclone(TC) Durian(2001) were investigated quantitatively using the three-dimensional(3 D) WRF-based precipitation equation. The rain rate(PS) decreased slightly as the TC approached to formation, and then increased as Durian began to intensify. The rate of moisture-related processes(QWV) in the equation contributed around 80% to PSbefore TC genesis, and made more contribution during and after TC genesis. The rate of hydrometeor-related processes(QCM) contributed about 20% before TC formation, followed by less contribution during and after TC formation. QWVwere dominated by the 3 D moisture flux advection rate(QWVA), while the surface evaporation rate(QWVE) also played an important role. Just before TC genesis, moisture from QWVAand QWVEhelped the local atmosphere moisten(negative QWVL). QCMwere determined by the 3 D hydrometeor advection rates(QCLAand QCIA) and the local change rates of hydrometeors(QCLLand QCIL). During TC formation, QCMlargely decreased and then reactivated as Durian began to intensify, accompanied by the development of TC cloud. Both the height and the strength of the net latent heating center associated with microphysical processes generally lowered before and during TC genesis, resulting mainly from lessening deposition and condensation. The downward shift of the net latent heating center induced a more bottom-heavy upward mass flux profile, suggesting to promote lower-tropospheric convergence in a shallower layer, vorticity amplification and TC spin-up.

START-UP AND DYNAMIC PROCESSES SIMULATION OF A DISTILLATION COLUMN

A new dynamic non-equilibrium mixing-pool model for simulating start-up and dynamic re-sponse of a distillation column is reported.The proposed model is established on the basis ofconsidering the two dimensional flow/mixing behavior of actual trays in a distillation column.Com-parison is made among the computed results of the start-up time and the dynamic response time bythe proposed and five other typical models.It is found that the computed time for both dynamicprocesses is longer by the model which considers any flow/mixing pattern than by the model withoutsuch concern.The inertia effect of flow/mixing seems to be important and can not be ignored inmodeling the transient process of distillation.The proposed model,which is believed to be suitableto large column,seems somewhat useful in predicting industrial distillation dynamics.

基于激光雷达扫描的料仓原料储料量测量方法

为提高仓内原料储料量测量自动化和智能化水平,设计了一种基于二维激光雷达扫描的储料量测量装置与系统。本系统采用RPLIDARS1型二维激光雷达扫描获取不同储料量物料的原始点云数据,通过坐标变换、重叠点提取、滤波、分割等方法对原始点云进行预处理,采用贪婪投影三角化算法将预处理后的点云进行三维重建,获得仓内原料的三维模型,结合物料三维模型和物料的容重获得仓内原料的储料量,从而实现储料量的自动测量。以玉米为试验对象,测量小型储料塔内玉米储料量并对玉米不同储料量进行扫描测量,验证模型的准确性,结果显示:测量结果的平均绝对误差为8.05kg,平均相对误差为1.52%。研究结果表明,基于二维激光雷达扫描的储料量测量方法是可行的,具有较好的稳定性和测量精度,能够满足实际生产需求。