Most injection molded parts are three-dimensional, with complex geometrical configurations and thick/thin wall sections. The change of the thickness of parts has significant influence on flow during injection molding....Most injection molded parts are three-dimensional, with complex geometrical configurations and thick/thin wall sections. The change of the thickness of parts has significant influence on flow during injection molding. This paper presents a 3D finite element model to deal with the three-dimensional flow, which can more accurately predict the filling process than a 2.5D model. In this model, equal-order velocity-pressure interpolation method is successfully employed and the relation between velocity and pressure is obtained from the discretized momentum equation in order to derive the pressure equation. A 3D control volume scheme is employed to track the flow front. The validity of the model has been tested through the analysis of the flow in a cavity.展开更多
Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its hi...Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its high computational efficiency and low resource usage.For more advanced scenarios,the existing methods still have a problem that the guidance accuracy and optimality will seriously degrade when the actual state largely deviates from the nominal trajectory.This is mainly caused by the approximate description of the first-order conditions in terms of total flight time and nonlinear constraints.To address this problem,a higher-order neighboring optimal guidance method is proposed.First,a novel total flight time updating strategy,together with a normalized time scale,is presented that transforms the optimal problem with free total flight time into a more tractable optimal problem with fixed total flight time.Then,using the vector partial derivative method,a higher-order approximation is adopted,instead of the first-order approximation,to accurately describe the nonlinear dynamical and terminal constraints,thus obtaining a polynomially constrained quadratic optimal problem.Finally,to numerically solve the polynomially constrained quadratic optimal problem,a Newton-type iterative algorithm based on the orthogonal decomposition is designed.Through the iterative solution within each guidance period,the corrections to control quantities and total flight time are generated.The proposed method is applied to a launch vehicle orbital injection problem,and simulation results show that it achieves high accuracy of orbital injection and optimality of performance index.展开更多
针对现有注塑工艺参数稳健设计未安排外表试验以深入分析成型过程中不可控因素的影响、未综合考虑注塑制品的多质量特性等不足,提出基于内外表参数设计、信噪比分析和逼近理想解排序(Technique for order preference by similarity to i...针对现有注塑工艺参数稳健设计未安排外表试验以深入分析成型过程中不可控因素的影响、未综合考虑注塑制品的多质量特性等不足,提出基于内外表参数设计、信噪比分析和逼近理想解排序(Technique for order preference by similarity to ideal solution,TOPSIS)的注塑工艺多目标稳健优化设计方法。通过二水平正交试验和方差分析筛选出对注塑制品质量影响最大的主要工艺参数作为可控因素,将其误差作为噪声因素,进行内外表参数设计。利用均匀试验设计和逐步回归分析建立预测给定注塑工艺方案下成型制品质量的二次多项式模型,以快速获得内外表所有试验方案下成型制品的质量指标值,进而高效地计算出内表试验方案下各质量指标所对应的信噪比。在此基础上,利用TOPSIS对内表各试验方案进行优劣排序并选取稳健最优的注塑工艺参数设计方案。手机面板的注塑工艺多目标稳健优化设计实例验证了方法的有效性。展开更多
目的探讨运用失效模式效应分析(Failure Mode and Effect Analysis,FMEA)评估并改进核对注射口服医嘱方法的效果。方法采用FMEA评估核对注射口服医嘱原有流程的危机值,并对注射口服医嘱核对流程进行改进:1名护士负责看病历只读注射或口...目的探讨运用失效模式效应分析(Failure Mode and Effect Analysis,FMEA)评估并改进核对注射口服医嘱方法的效果。方法采用FMEA评估核对注射口服医嘱原有流程的危机值,并对注射口服医嘱核对流程进行改进:1名护士负责看病历只读注射或口服医嘱的药名,对于成组的医嘱,只读第1种药名及剂量;1名护士负责核对录入电脑医嘱,只读药物的剂量,对于成组医嘱,只读第2种药名及剂量;另1名护士负责核对各种治疗本,对于成组医嘱,只读药物的用法及次数;下午重复以上工作。将2008年5月—2010年5月运用FMEA改进核对注射口服医嘱流程后护理差错发生情况与2006年4月—2008年4月改进前进行比较。结果运用FMEA改进核对注射口服医嘱流程后核对医嘱出错而发生的护理缺陷、漏收费、多收费、投诉较改进前减少,其中漏收费、多收费比较差异有统计学意义(P<0.05)。结论运用FMEA评估并改进核对注射口服医嘱流程能及时发现护理缺陷,有效避免护理差错的发生,降低护理投诉与纠纷,提高护理质量。展开更多
文摘Most injection molded parts are three-dimensional, with complex geometrical configurations and thick/thin wall sections. The change of the thickness of parts has significant influence on flow during injection molding. This paper presents a 3D finite element model to deal with the three-dimensional flow, which can more accurately predict the filling process than a 2.5D model. In this model, equal-order velocity-pressure interpolation method is successfully employed and the relation between velocity and pressure is obtained from the discretized momentum equation in order to derive the pressure equation. A 3D control volume scheme is employed to track the flow front. The validity of the model has been tested through the analysis of the flow in a cavity.
基金This study was co-supported by the National Natural Science Foundation of China(No.62103014).
文摘Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its high computational efficiency and low resource usage.For more advanced scenarios,the existing methods still have a problem that the guidance accuracy and optimality will seriously degrade when the actual state largely deviates from the nominal trajectory.This is mainly caused by the approximate description of the first-order conditions in terms of total flight time and nonlinear constraints.To address this problem,a higher-order neighboring optimal guidance method is proposed.First,a novel total flight time updating strategy,together with a normalized time scale,is presented that transforms the optimal problem with free total flight time into a more tractable optimal problem with fixed total flight time.Then,using the vector partial derivative method,a higher-order approximation is adopted,instead of the first-order approximation,to accurately describe the nonlinear dynamical and terminal constraints,thus obtaining a polynomially constrained quadratic optimal problem.Finally,to numerically solve the polynomially constrained quadratic optimal problem,a Newton-type iterative algorithm based on the orthogonal decomposition is designed.Through the iterative solution within each guidance period,the corrections to control quantities and total flight time are generated.The proposed method is applied to a launch vehicle orbital injection problem,and simulation results show that it achieves high accuracy of orbital injection and optimality of performance index.
文摘针对现有注塑工艺参数稳健设计未安排外表试验以深入分析成型过程中不可控因素的影响、未综合考虑注塑制品的多质量特性等不足,提出基于内外表参数设计、信噪比分析和逼近理想解排序(Technique for order preference by similarity to ideal solution,TOPSIS)的注塑工艺多目标稳健优化设计方法。通过二水平正交试验和方差分析筛选出对注塑制品质量影响最大的主要工艺参数作为可控因素,将其误差作为噪声因素,进行内外表参数设计。利用均匀试验设计和逐步回归分析建立预测给定注塑工艺方案下成型制品质量的二次多项式模型,以快速获得内外表所有试验方案下成型制品的质量指标值,进而高效地计算出内表试验方案下各质量指标所对应的信噪比。在此基础上,利用TOPSIS对内表各试验方案进行优劣排序并选取稳健最优的注塑工艺参数设计方案。手机面板的注塑工艺多目标稳健优化设计实例验证了方法的有效性。
文摘目的探讨运用失效模式效应分析(Failure Mode and Effect Analysis,FMEA)评估并改进核对注射口服医嘱方法的效果。方法采用FMEA评估核对注射口服医嘱原有流程的危机值,并对注射口服医嘱核对流程进行改进:1名护士负责看病历只读注射或口服医嘱的药名,对于成组的医嘱,只读第1种药名及剂量;1名护士负责核对录入电脑医嘱,只读药物的剂量,对于成组医嘱,只读第2种药名及剂量;另1名护士负责核对各种治疗本,对于成组医嘱,只读药物的用法及次数;下午重复以上工作。将2008年5月—2010年5月运用FMEA改进核对注射口服医嘱流程后护理差错发生情况与2006年4月—2008年4月改进前进行比较。结果运用FMEA改进核对注射口服医嘱流程后核对医嘱出错而发生的护理缺陷、漏收费、多收费、投诉较改进前减少,其中漏收费、多收费比较差异有统计学意义(P<0.05)。结论运用FMEA评估并改进核对注射口服医嘱流程能及时发现护理缺陷,有效避免护理差错的发生,降低护理投诉与纠纷,提高护理质量。
