基于中面模型和三维模型的气辅注射成型数值模拟及物理实验研究

在研究2.5维模型和三维模型等注射成型数值模拟技术的基础上,采用MoldFlow模流分析软件就同一气辅塑件分别进行了基于中面模型和三维模型的气体辅助注射成型数值模拟,并进行了物理实验研究。通过对模拟分析结果和实验结果的对比分析,表明基于中面模型的模拟结果需要较高的熔体预注射量,并且夸大了气指缺陷的程度,模拟结果与物理实验结果的偏差较大。而基于三维模型的气体穿透情况及气指缺陷情况都与物理实验结果吻合的较好,在很大程度上真实、可靠地预测了塑件的成型过程,满足了指导生产的需求。

一种新型高精度的中位面法储油罐罐容测算研究

提出了一种新的储油罐罐容计算方法,有较高的精确度和较低的计算复杂度,并用形象的图形给出了罐体变位前后罐容表,达到良好的仿真结果分析,能够很好的推广应用。

注塑成形CAE系统分析模型研究

目前共有4种分析模型应用于注塑成形CAE系统:1维分析模型;2·5维中面分析模型;2·5维双面网格分析模型;3维实体分析模型。详细讨论了2·5维中面分析模型,2·5维双面网格分析模型和3维实体分析模型3种分析模型的优缺点,并通过理论分析和实例模拟结果的比较,研究了不同分析模型对注塑分析结果的影响,提出了在使用CAE系统中选择分析模型的规则。

塑料制件最大流长比算法研究与应用

提出了计算塑料制件最大流长比 (流动长度与厚度的比值 )的算法。该算法利用三角形网格模型表示复杂制件的中面模型 ,通过对三角单元的带权边进行细分 ,由细分得到的点、边和原三角网格模型上的节点构成带权图G ,采用快速最短路径法 (FSPA)动态计算带权图上两点的最短路径 ,从而得到制件上由一点到任意点的最短路径值即流长比。该算法效率高 ,容易实现 ,可通过改善网格质量和调整细分参数γ控制近似精度。给出了该算法的两个应用实例。

注塑流动与传热分析的四边形单元控制体积法

阐述了注塑分析的基于Hele-Shaw假设四边形单元控制体积法。由于四边形控制体积法会产生不对称矩阵的方程组,求解压力时把方程不对称的部分移到方程右边,这样方程转化为对称的线性方程组。在求解转化后的线性方程组时,只在压力求解区域改变时更新方程的右边。注塑分析的时间步长进行自动调整,并大致保证流动前锋在两个时间步内向前流动大略一单元层。与现有文献的计算结果比较表明四边形单元控制体积法可以有效地模拟中面模型的注射过程,该方法并可以与三角形单元混合使用,且可应用于基于表面的注塑分析方法。

基于实体的注射成型流动模拟

提出了应用中面模型技术模拟实体模型的注射成型流动过程的新方法。对实体模型的表面进行二维网格划分,将结点在厚度方向上配对,配对点之间添加虚拟热流道单元,建立二维有限元分析的网格模型。将Hele-Shaw流动应用于非等温条件下的粘性、不可压缩流体,建立基于中面模型流动分析的数学模型,用充填因子的输运方程描述流动前沿。用有限元计算充填过程的压力场,有限差分计算温度场,高阶的Taylor展开式计算每一时间步长的充填因子。针对Han设计的试验模具,用相同的材料及工艺条件,比较中面模型和实体模型的模拟结果。算例分析表明,这种方法可以有效地模拟基于实体模型的注射成型流动过程。

实体上的流动分析(英文)

传统的应用"中面模型"技术的2 5维方法在预测薄壁制件成型过程中的流动行为是非常成功的,但"中面模型"在应用过程中是非常不方便的.通过使用实体表面作为流动平面,在厚度方向上添加虚拟热流道来保持熔体在实体表面一致地向前充填,并比较了模拟结果与Han的实验结果及摩托车后视镜的缺料注射结果.算例分析表明,这种方法对实体充填模拟是有效的.

Numerical Simulation of the Influence of Mean Sea Level Rise on Typhoon Storm Surge in the East China Sea

In this paper, ECOMSED （Estuarine Coastal Ocean Model with sediment transport） model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED to simulate storm surge is validated by comparing model result with observed data. Sensitivity experiments are designed to study the influence of sea level rise on typhoon storm surge. Numerical experiment shows that influence of mean sea level rise on typhoon storm surge is non-uniform spatially and changes as typhoon process differs. Maybe fixed boundary method would weaken the influence of mean sea level rise on storm surge, and free boundary method is suggested for the succeeding study.

基于UG的涡扇发动机风扇叶片变形分析方法研究

基于UG二次开发工具UG/OPEN API和NX OPEN C++以及C编程语言的二次开发功能,结合VS 2008平台对涡扇发动机风扇叶片结构进行叶片模型、有限元模型和仿真模型的参数化创建,同时研究叶身中弧面厚度信息的提取问题.将提取的厚度信息加载到壳单元网格上,使其具有实体特性,利用该单元对叶片进行网格划分,并进行求解分析,对比实体单元网格分析结果.仿真结果表明,在相同的计算模型下,实体壳单元能够减少计算时占用内存的24.65%和计算时间的45.97%,提高计算效率,减少计算周期.

Crustal Movement Patterns of China Continent Measured by GPS

This paper uses multi-quadric equations interpolation to es-tablish a widely covered and valuablespeed field model of China, withwhich the horizontal crustal movementpatterns are obtained. The present-dayvertical crustal movement velocity im-age of China is also expressed by GPSobservations, from which we canknow the vertical crustal movementpatterns.

Effects of continuous casting mould fluxes on reducing longitudinal and star cracks on a slab surface

In the continuous casting production of medium carbon steel (whose mass fraction of carbon is 0.09 % to 0.16 %) and high strength low alloy steel (whose mass fraction of Mn is 0.90 % to 1.40 %), flecks occurring the most often are usually longitudinal and star cracks. In additional to the employment of a galvanized plate mould, two kinds of fluxes with special properties were studied and used to harmonize the conflicts between the function of heat transfer and lubrication. An industrial application revealed that the crystallizing temperature (Tc) and crystal ratio (R) of fluxes have a crucible effect on impeding the occurrence of above defects on a slab surface. In the case of slab section (180 to 240) mm(1000 to 1400) mm and casting speed Vc of (0.7 to 1.2) m/min, the optimized parameters of fluxes are Tc of (1170 to 1190) ℃, R of 80 % to 95 % for medium carbon steel, and Tc of (1100 to 1150) ℃, plus R of 40 % to 60 % for high strength low alloy steel.

Subdaily to Seasonal Change of Surface Energy and Water Flux of the Haihe River Basin in China: Noah and Noah-MP Assessment

The land surface processes of the Noah-MP and Noah models are evaluated over four typical landscapes in the Haihe River Basin(HRB) using in-situ observations. The simulated soil temperature and moisture in the two land surface models(LSMs) is consistent with the observation, especially in the rainy season. The models reproduce the mean values and seasonality of the energy fluxes of the croplands, despite the obvious underestimated total evaporation. Noah shows the lower deep soil temperature. The net radiation is well simulated for the diurnal time scale. The daytime latent heat fluxes are always underestimated, while the sensible heat fluxes are overestimated to some degree. Compared with Noah, Noah-MP has improved daily average soil heat flux with diurnal variations. Generally, Noah-MP performs fairly well for different landscapes of the HRB. The simulated cold bias in soil temperature is possibly linked with the parameterized partition of the energy into surface fluxes. Thus, further improvement of these LSMs remains a major challenge.

Evaluation of the WRF Model with Different Land Surface Schemes: A Drought Event Simulation in Southwest China during 2009–10

The authors examined the performance of version 3.4.1 of the Weather Research and Forecasting Model(WRF) with various land surface schemes in simulating a severe drought event in Southwest China. Five numerical experiments were completed using the Noah land surface scheme, the Pleim-Xiu land surface scheme, the Noah-MP land surface schemes, the Noah- MP scheme with dynamic vegetation, and the Noah-MP scheme with dynamic vegetation and groundwater processes. In general, all the simulations reasonably reproduced the spatial and temporal variations in precipitation, but significant bias was also found, especially for the spatial pattern of simulated precipitation. The WRF simulations with the Noah-MP series land surface schemes performed slightly better than the WRF simulation with the Noah and Pleim-Xiu land surface schemes in reproducing the severe drought events in Southwest China. The leaf area index(LAI) simulated by the different land surface schemes showed significant deviations in Southwest China. The Pleim-Xiu scheme overestimated the value of LAI by a factor of two. The Noah-MP scheme with dynamical vegetation overestimated the magnitude of the annual cycle of the LAI, although the annual mean LAI was close to observations. The simulated LAI showed a long-term lower value from autumn 2009 to spring 2010 relative to normal years. This indicates that the LAI is a potential indictor to monitor drought events.

基于UG的风扇叶片反造型设计方法

基于UG二次开发工具UG/OPEN API和NX OPEN C/C++二次开发功能,结合C/C++编程语言在VS2008平台创建涡扇发动机风扇叶片叶身的中弧面参数化模型和有限元参数化模型,并进行仿真分析。利用壳单元进行分析,对生成的NX Nastran输入输出文件进行数据处理,完成有限元模型的反向迭代过程。该过程能够获得叶片结构的预变形,使得到的叶片模型在外载荷和边界约束条件下,得到与原始模型相互重合的叶片模型。

Secure planar convex hull protocol for large-scaled point sets in semi-honest model

Efficiency and scalability are still the bottleneck for secure multi-party computation geometry （SMCG）. In this work a secure planar convex hull （SPCH） protocol for large-scaled point sets in semi-honest model has been proposed efficiently to solve the above problems. Firstly, a novel priva- cy-preserving point-inclusion （PPPI） protocol is designed based on the classic homomorphic encryp- tion and secure cross product protocol, and it is demonstrated that the complexity of PPPI protocol is independent of the vertex size of the input convex hull. And then on the basis of the novel PPPI pro- tocol, an effective SPCH protocol is presented. Analysis shows that this SPCH protocol has a good performance for large-scaled point sets compared with previous solutions. Moreover, analysis finds that the complexity of our SPCH protocol relies on the size of the points on the outermost layer of the input point sets only.

An Unsteady Heterogeneous Mass Transfer Model for Gas Absorption Enhanced by Dispersed Third Phase Droplets

A model for one-dimensional unsteady heterogeneous mass transfer was developed based on Danck-werts' surface renewal theory in order to describe the mass transfer enhancement of absorption process for a slightly soluble gas in a gas-liquid-liquid system.The model accounts for the mass transfer resistance within the dispersed phase and the effect of emulsion viscosity on mass transfer.An analytical solution for enhancement factor was obtained by Laplace domain transformation.The absorption rates of carbon dioxide in the dodecane-in-water and castor oil-in-water systems were measured in a thermostatic reactor,and the enhancement factors were calculated at different volume fractions of dispersed phase and stirrer speeds.The model predictions agree well with the experimental data.

Modeling a habitat suitability index for the eastern fall cohort of Ommastrephes bartramii in the central North Pacific Ocean

The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and identify their optimal habitat, we have developed a habitat suitability index （HSI） model using two potential important environmental variables -- sea surface temperature （SST） and sea surface height anomaly （SSHA） -- and fishery data from the main fishing ground （165°-180°E） during June and July of 1999-2003. A geometric mean model （GMM）, minimum model （MM） and arithmetic weighted model （AWM） with different weights were compared and the best HSI model was selected using Akaike＇s information criterion （AIC）. The performance of the developed HSI model was evaluated using fishery data for 2004. This study suggests that the highest catch per unit effort （CPUE） and fishing effort are closely related to SST and SSHA. The best SST- and SSHA-based suitability index （SI） regression models were SISST-based = 0.7SIeffort-SST ＋ 0.3 SICPUE-SST, and SISSHA-based =0.5Sleffort-SSHA ＋ 0.5SICPUE-SSHA, respectively, showing that fishing effort is more important than CPUE in the estimation of SI. The best HSI model was the AWM, defined as HSI=0.3SISSHA-based＋ 0.7SISSHA-based, indicating that SSHA is more important than SST in estimating the HSI of squid. In 2004, monthly HSI values greater than 0.6 coincided with the distribution of productive fishing ground and high CPUE in June and July, suggesting that the models perform well. The proposed model provides an important tool in our efforts to develop forecasting capacity of squid spatial dynamics.

Projections of 2.0°C Warming over the Globe and China under RCP4.5

The outputs of 17 models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) are employed to investigate the temporal and spatial features of 2.0°C warming of the surface temperature over the globe and China under the Representative Concentration Pathways (RCP) 4.5 scenario. The simulations of the period 1860-1899 in the "historical" experiment are chosen as the baseline. The simulations for the 21st century in the RCP4.5 experiment are chosen as the future project. The multi-model ensemble mean (MME) shows that the global mean temperature would cross the 2.0°C warming threshold in 2047. Warming in most of the models would cross the threshold during 2030-2060. For local warming, high-latitude areas in the Northern Hemisphere show the fastest warming over the globe. Land areas warm substantially faster than the oceans. Most of the southern oceans would not exceed the 2.0°C warming threshold within the 21st century. Over China, surface warming is substantially faster than the global mean. The area-averaged warming would cross the 2.0°C threshold in 2034. Locally, Northwest China shows the fastest warming trend, followed by Central North China and Northeast China. Central China, East China, and South China are the last to cross the 2.0°C warming threshold. The diversity of the models is also estimated in this study. Generally, the spread among the models increases with time, and there is smaller spread among the models for the areas with the faster warming.

Theoretical Analysis of Neutron Double-Differential Cross Sections of n ＋^9Be Reactions

By using the nuclear reaction model for light nuclei, the calculations of the double-differential cross sections of outgoing neutrons from n ＋^9Be reactions are performed. The total outgoing neutrons are only come from the （n, 2n）2a reaction channel. The （n, 2n）2a reaction channel is achieved through six different reaction approach, which are illustrated in this paper. The calculated results agree very well with the measured data at En = 7.1, 8.09, 8.17, 9.09, 9.97 and 10.26 MeV, because the updated level schemes related to the n ＋ ^9Be reactions have been employed in this calculations.

Influences of the interannual variability of vegetation LAI on surface temperature

The influences of interannual variability of vegetation LAI on surface temperature are investigated via two ensemble simulations, applying the Community Earth System Model. The interannual LAI, derived from Global Inventory Modeling and Mapping Studies NDVI for the period 1982-2011, and its associated climatological LAI, are used in the two ensemble simulations, respectively.The results show that the signals of the influences, represented as ensemble-mean differences, are generally weaker than the noises of the atmospheric variability, represented as one standard deviation of the ensemble differences. Spatially, the signals are stronger over the tropics compared with the mid-high latitudes. Such stronger signals are contributed by the significant linearity between LAI and surface temperature, which is mainly caused via the influences of LAI on evapotranspiration.The maximum amplitudes of the influences on the interannual variability of surface temperature are high and thus deserve full consideration. However, the mean magnitudes of influences are small because of the small changes in the amplitudes of LAI. This work only investigates the influences of the interannual variability of LAI and does not consider interannual changes in other vegetation characteristics, such as canopy height and fractional cover. Further work involving dynamic vegetation models may be needed to investigate the influences of vegetation variability.