空降车着陆缓冲过程结构强度分析方法研究

为了研究空降车着陆缓冲过程中的结构强度,采用有限元方法建立了车体-气囊有限元模型,在两种工况下进行仿真计算,获得最大加速度结果,并将有限元仿真与加速度试验结果对比。仿真结果能准确反映空降车着陆缓冲过程,车体冲击加速度满足着陆缓冲过程的要求。进一步得到了正常着陆工况和恶劣着陆工况下车体的应力分布情况,结果表明,车体最大Von Mises应力小于材料的抗拉强度,车体的结构强度满足设计要求。     

基于部分战损情况下的导弹武器系统可用度分析

对复杂战场条件的导弹武器系统可用度评估进行了研究。假定部件的寿命服从指数分布,修理时间和保障延误时间均服从任意分布,并且修理设备服务期服从指数分布,其更换时间服从任意分布的情况下,利用马尔可夫更新过程理论和拉普拉斯变换工具,建立了考虑技术阵地设备部分战损情况下和具有保障延误的串联可修导弹武器系统可用度模型,并进行了验证。算例结果与前期仿真结果吻合,验证了模型的可行性,为非马尔可夫型系统的可用度分析提供了有效的方法。     

基于更新过程的导弹武器系统可用度分析

针对在导弹武器系统可用度评估中,各时间参数分布不完全服从指数分布,且不能用马尔科夫过程来分析的缺点,利用更新过程,建立考虑保障延误的串联可修导弹武器系统的可用度模型,并进行实例应用。结果表明:算例结果与前期仿真结果吻合,验证了模型的可行性,可为非马尔科夫型系统的可用度分析提供有效方法。     

邯邢铁矿平地式选矿厂的设计

建设平地式选矿厂,地形是不利条件,本文举例介绍了设计平地式选矿厂的主要问题及解决方法。     

机械制造基础课程项目教学法的探索与实践

针对高职两年制数控专业学制短的特点,结合三年制机电专业同等课程在教学中遇到的一些问题,本着让学生更好掌握机械制造基础课程知识和专业技能的原则,采用项目教学法,收到良好的教学效果。     

Optimization of solvent crystallization process in obtaining high purity anthracene and carbazole from crude anthracene

Solvent crystallization is the main method used for preparing anthracene and carbazole from the crude anthracene. The key to the optimization of this method is improving the solubility selectivity of the solvent by means of solvent modulating and process optimization. In this study, the solubility of anthracene, phenanthrene, and carbazole in xylene, dimethylformamide (DMF), DMF with amine/amide, isopropanolamine, and chlorobenzene is examined and the solid‐liquid ternary anthracene–carbazole–DMF/(DMF+19.96% isopropanolamine) system phase diagram is determined and applied in the solvent crystallization process. The results showed that the solubility selectivity of xylene increases with increased temperature. Also, selectivity increases with an increase of the amount of isopropanolamine in the mixture of DMF and isopropanolamine, while decreases with increased temperature. Through multiple washings of crude anthracene with xylene, DMF+19.96% isopropanolamine, and chlorobenzene, it was possible to obtain anthracene and carbazole of purity higher than 98 wt %. © 2013 American Institute of Chemical Engineers AIChE J, 60: 275–281, 2014     

Modeling and validation of the iodine‐sulfur hydrogen production process

The iodine‐sulfur thermochemical water‐splitting cycle (I‐S process) is one of the highly efficient, CO₂‐free, massive hydrogen production methods. We simulated the I‐S process through commercial software programs Aspen Plus and OLI database with the aid of self‐developed models to analyze the overall running status of the process and to decrease the investment and time consumption of experiments. A two‐phase separator model operating at 353 K and an electro‐electrodialysis (EED) cell model working at 338 K were built on the basis of experimental data. The entire flow sheet of the I‐S process was modeled based on the two self‐developed models. The simulation models were validated through the experimental results obtained from the closed cycle I‐S facility (IS‐10) in our laboratory. By employing the simulation program, sensitivity analyses of the important parameters in the process were carried out, including the ratio of the distillate to the feed rate of the H₂SO₄ distillation column, reflux ratio of the H₂SO₄ column, H₂SO₄ conversion ratio, HI molality in the EED cathode outlet stream, and HI mole fraction in the liquid and vapor distillates of the HI distillation column. The key parameters significantly affecting the input duty were determined; that is, the ratio of the distillate to the feed rate of the H₂SO₄ distillation column and the HI molality in the EED cathode outlet stream. The optimal values of the analyzed parameters were also discussed. The simulation program we developed is a useful tool that can evaluate and optimize the I‐S process. © 2013 American Institute of Chemical Engineers AIChE J 60: 546–558, 2014     

On the tuning of predictive controllers: Impact of disturbances,constraints, and feedback structure

The impact of problem formulation modifications on predictive controller tuning is investigated. First, the proposed tuning method is shown to adapt to disturbance characteristic changes and thus, takes full economic advantage of the scenario. The second topic concerns point‐wise‐in‐time constraints and the impact of constraint infeasibility. Specifically, we shift the tuning question from selection of nonintuitive weighting matrix parameters to that of a few key parameters and results in a rather intuitive trade‐off between expected profit and expected constraint violations. Finally, we show that simple modifications will allow for the consideration of various feedback structures, including computational delay and partial state information. The overall conclusions of the work are that the results of the automated algorithm will help build an intuitive understating of the dynamics of the process and ultimately result in a higher level trade‐off between profit and constraint observance. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3473–3489, 2014     

Quality assurance of Chinese herbal medicines: Procedure for multiple‐herb extraction

A quality assurance (QA) procedure for multiple‐herb extraction, which takes into account the existence of common chemical markers and multiple‐herb‐extraction effects, has been developed for producing Chinese herbal medicines (CHMs) of consistent quality. The experimental method for determining related correlation function of the multiple‐herb‐extraction effect was designed. A systematic solution strategy was also developed to appropriately decompose the multiple‐herb extraction system into several subsystems for obtaining solution(s) and determining the overall behavior of the system. An example of QA of Danshen–Gegen (DG) decoction was used to demonstrate the QA procedure. An H9c2 cell assay was used to test the efficacy of consistent quality DG decoctions prepared by different herb combinations with different material costs of herbs. It was observed that a multiple‐herb‐extraction effect was present in the aqueous extraction of Danshensu and this effect was depended on the extraction solvent. The possible mechanism of this multiple‐herb‐extraction effect in the aqueous DG extraction was speculated to be the change of initial pH value of the aqueous extraction solvent by an unknown component from Gegen. The experimental chemical marker concentrations fell within ±10% of the specified chemical marker compositions by using the amount of herb from each herb class as predicted by the QA model. Furthermore, an H9c2 cell assay was used to test the efficacy of three consistent quality DG extracts, which were produced by different herb combinations with different material costs of herbs. The results showed that the three DG extracts provided consistent biological efficacy against menadione‐induced toxicity. This study extended a recently developed QA procedure of single‐herb extraction to multiple‐herb extraction. It provides a solution of QA in extraction, which is one of the most important unresolved problems in the modernization of traditional Chinese medicines. With this modified model and the companion experiments, the amount of herbs needed from different quality classes to produce a multiple‐herb formula CHM product decoction with consistent quality can be exactly determined. © 2014 American Institute of Chemical Engineers AIChE J 60: 4014–4026, 2014