摘要：文章探讨了利用monte Carlo方法对改进的PPS抽样进行模拟,并对改进的PPS抽样设计效应进行了评价。文章从改进的PPS抽样以及PPS抽样设计效应入手,分析了改进的PPS抽样的设计效应的计算;并结合具体实例,对改进的PPS抽样进行了monte Carlo模拟。

摘要：下死点动态精度是评价压力机性能的重要指标之一,决定着冲压件的冲压质量。在瞬时可靠度理论的基础上建立了高速冲床运动精度可靠性的计算模型,并用瞬时状态矩阵对monte Carlo模拟方法进行改进和简化。基于改进后的monte Carlo模拟方法分析了JF75G-300高速冲床在不同速度下制造误差、弹性变形和运动副间隙对运动精度可靠性的影响。仿真结果表明:不同速度下的位移误差均服从正态分布,且随着速度的提高位移误差的波动量增大,运动精度的瞬时可靠性明显降低。通过测量JF75G-300高速冲床不同速度下的下死点动态精度,验证了速度变化对冲床运动精度可靠性影响的模拟结果。以上模拟方法可在设计阶段对冲床的下死点动态精度进行预测,为加工精度、杆件刚度及装配精度的选择和优化提供理论基础。

摘要：障碍期权是国内OTC市场报价交易频繁的一种典型期权,该类期权偿付的跳跃结构和路径依赖性使得障碍期权的对冲一直是业界技术难题.通过对挂钩沪深300指数的向上敲出障碍期权的定价对比分析,设计了一款适用于目前国内金融市场的障碍期权的对冲策略.主要通过Black-Scholes-Merton模型解析解和monte Carlo模拟方法进行期权定价和分析障碍期权的Greeks的变动情况,依据delta的变化进行静态复制最大成本的测算和动态障碍价格外移边界的分析以及10 000条指数路径的模拟对冲,分析其平均对冲成本和极值效应,并选取2011～2016年沪深300指数实际样本进行对冲策略的回测.结果显示在遍历法触发式外移障碍边界的对冲思路下对冲平均成本显著降低,同时对冲极值和分位数的分布相对平滑,这反映了对冲策略表现良好,实现了障碍期权的有效对冲.

摘要：通过monte Carlo法模拟抽样出应力和强度的大量样本值,得到建立应力-强度样本干涉模型的数据原型。运用概率纸检验数据分布,直观地确定了应力或强度模拟样本值分布类型。应用极大似然估计确定应力和强度总体分布参数,从而最终得到应力-强度总体干涉数据模型。以蜗轮结构可靠性设计模拟出总体干涉模型,再计算出可靠度为0.999 6,为可靠性数据缺乏时进行机械零件可靠性设计提供了一种思路,具有一定的参考价值。

摘要：多腔体的微型可降解高分子聚合物PLGA药物缓释系统是一种新型植入式给药微器件,其载体结构是结合药物释放的要求和高分子聚合物生物降解特性进行设计并利用MEMS工艺制备.为了解微型给药系统实际释药的性能,需要对其进行建模和仿真研究.基于体溶蚀的monteCarlo溶蚀模型,建立了具有多腔体的微型PLGA给药载体的释药模型,并对腔体结构为圆形的微型给药系统进行了释药过程仿真.仿真结果表明本文建立的微系统释药模型可以较为准确的描述微系统的释药过程,仿真模型对进一步开发微型PLGA给药系统有重要的参考价值.

摘要：This research work investigated comparative studies of expert system design and control of crude oil distillation column (CODC) using artificial neural networks based monte Carlo (ANNBMC) simulation of random processes and artificial neural networks (ANN) model which were validated using experimental data obtained from functioning crude oil distillation column of Port-Harcourt Refinery, Nigeria by MATLAB computer program. Ninety percent (90%) of the experimental data sets were used for training while ten percent (10%) were used for testing the networks. The maximum relative errors between the experimental and calculated data obtained from the output variables of the neural network for CODC design were 1.98 error % and 0.57 error % when ANN only and ANNBMC were used respectively while their respective values for the maximum relative error were 0.346 error % and 0.124 error % when they were used for the controller prediction. Larger number of iteration steps of below 2500 and 5000 were required to achieve convergence of less than 10-7?for the training error using ANNBMC for both the design of the CODC and controller respectively while less than 400 and 700 iteration steps were needed to achieve convergence of 10-4?using ANN only. The linear regression analysis performed revealed the minimum and maximum prediction accuracies to be 80.65% and 98.79%;and 98.38% and 99.98% when ANN and ANNBMC were used for the CODC design respectively. Also, the minimum and maximum prediction accuracies were 92.83% and 99.34%;and 98.89% and 99.71% when ANN and ANNBMC were used for the CODC controller respectively as both methodologies have excellent predictions. Hence, artificial neural networks based monte Carlo simulation is an effective and better tool for the design and control of crude oil distillation column.

摘要：Shielding design is necessary for brachytherapy treatment room in order to protect the general public and employees. The main objective of this study was to investigate whether the protective unit of our Brachytherapy Centre provided adequate protection to the health and safety assessment of radiobiological impact. In this study, we estimated the effect of radiobiological protection from a single Ir-192 brachytherapy source in Brachytherapy center by using MCNP5 monte Carlo measurements. The room was based on the design specifications for the HDR 192 Ir treatment was modeled. The estimated dose rate range for HDR 192 Ir and public buildings is (0.45 - 0.64): (micro sivert) μSv/hour. Dose rates measured data for the current setup Brachytherapy HDR unit was approved and agreed quiet well with recommendation of International Atomic Energy Agency. The measured dose rate for public areas and controlled areas, compared with the reference value of 7.5 μSv/h and 0.5 μSv/h and concluded that we have enough shielding to the source but an over estimate with experimental measurements had been seen.

摘要：背景:聚乳酸-乙醇酸广泛应于医用植入物与药物缓释载体,由于影响其降解过程的因素较多,使得其失重性能难以模拟。目的:对聚乳酸-乙醇酸膜失重性能进行数值模拟,观察模拟与实际测量的相关性。设计:重复测量。单位:大连理工大学材料科学与工程学院。材料:重均分子量分别为63000,115000和400000的实验用的聚乳酸-乙醇酸50/50,70/30和75/25,购自山东省医用高分子材料重点实验室。1,4-二氧六环为天津化学试剂一厂生产,用作溶剂。方法:实验于2006-04/06在大连理工大学材料科学与工程学院完成。①将聚乳酸-乙醇酸分别按质量比50∶50,70∶30及75∶25溶于1,4-二氧六环,溶液浇铸成10mm×10mm×1mm的聚合物膜。②聚乳酸-乙醇酸膜在37℃的Hank's模拟体液(pH7.4)中浸泡,每周取出1次(质量比为50:50的聚乳酸-乙醇酸为每5天取1次),试样清洗并干燥之后使用凝胶渗透色谱仪测量其数均与重均分子量,计算降解速率。同时使用电子天平测量其失重性能,并与monteCarlo法改进后实际测量值进行相关性分析。主要观察指标:①不同质量比聚乳酸-乙醇酸的降解速率。②模拟结果与实验值之间的相关系数。结果:①质量比50:50,70:30和75:25的聚乳酸-乙醇酸降解速率分别为0.0585,0.0166和0.0101/d(数均分子量)或者0.0610,0.0175和0.0085/d(重均分子量)。②聚乳酸-乙醇酸50/50,70/30和75/25的模拟结果与实验值之间的相关系数分别为0.9736,0.9874和0.9903。结论:数值模拟聚乳酸-乙醇酸膜失重性能与实验值符合良好。

摘要：通过在粗粒化模型中引入聚合反应机制,探讨自由基聚合反应动力学的monte Carlo模拟方法,研究自由基调聚反应的动力学过程.通过改变链转移剂的浓度、活性和加入时间,系统考察各反应条件对聚合反应动力学和聚合产物组成的影响.模拟研究发现,链转移剂的浓度和活性对聚合反应速率影响较弱;链转移剂的浓度和加入时间对单官能度聚合产物的影响较明显;双官能度聚合产物受链转移剂浓度和活性影响较强.模拟研究有助于设计聚合反应体系和分析聚合产物组成,具有重要的理论和应用价值.

摘要：无线传感器网络作为一种全新的信息获取和处理技术,可以在广泛的应用领域内实现复杂的大规模监测和追踪任务.在传感器网络中,确定事件发生的位置或获取消息的节点位置是传感器最基本的功能和支撑技术.本文针对特定的应用场景,设计了适用于锚节点固定,节点自由移动的移动传感器网络的基于monte Carlo方法的精确定位算法,并描述了其节点运动预测和位置选取模型,最后通过实验将本算法与以往研究成果中的代表性的移动传感器网络定位算法进行了模拟比较和分析.