两种前处理方法测定菜籽油中6种金属元素含量的比较

目的:比较不同前处理方法对菜籽油中6种金属元素含量测定的影响.方法:分别使用干灰化法和湿消化法进行前处理,并用火焰原子吸收分光光度法分别测定15个菜籽油样品中铅、镉、铜、铁等6种金属元素的含量.结果:干灰化法和湿消化法处理后所测菜籽油样品中Pb、Cu含量差异无统计学意义(P>0.05),Fe、Mn含量差异有统计学意义(P<0.05).各元素的R2均大于0.99,干灰化法的加标回收率81.90%~107.45%,湿消化法的加标回收率99.90%~108.05%.均满足痕量分析要求,相比之下,干灰化法与湿消化法的加标回收率比较差异有统计学意义(P<0.05),且湿消化法-火焰原子吸收分光光度法测定油样的回收率相对干灰化法的要高.结论:两种方法都能获得准确的测定结果;湿消化法要优于干灰化法.     

基于正交设计试验的双锥药型罩结构优化

双锥药型罩成形的影响因素复杂,其壁厚、上锥角、下锥角以及上锥高度占比4个参数对形成射流的特性、侵彻性能产生重要影响。基于正交设计方法分析以上因素对射流特性及侵彻能力的影响。选取双锥药型罩的以上4个参数为正交优化的4个因素,将射流头部速度、速度梯度以及有效长度作为优化时主要的评价指标,对双锥药型罩进行结构方案优化。通过分析双锥药型罩数值仿真优化结果,得到药型罩上锥角为25°、下锥角为55°、壁厚为3.5 mm、上锥占比60%时,其形成的射流具有较好的破甲效果。     

正交试验法优选坚龙胆中龙胆苦苷的提取工艺

目的:优选坚龙胆中龙胆苦苷的提取工艺.方法:以龙胆苦苷的含量为指标,采用高效液相色谱法进行含量测定,采用L9(34)正交设计试验,对提取次数、提取溶剂倍数和提取时间3因素进行考察,以确定最佳提取工艺.结果:提取3次,用10倍量的甲醇,提取时间每次20min为最佳提取工艺.结论:该工艺合理,且稳定可行.     

Undoped semi-insulating indium phosphide (InP) and its applications

During the past several years, the research and development of InP material has made great progress due to serving as the substrate for most optoelectronic devices operating at the communications wavelength of 1.31 and 1.55 μm. At present, InP has become an important semiconductor material together with Si and GaAs. When compared to GaAs, InP has higher electron velocity, higher radiation hardness and better heat-conducting property. The advantage of InP crystal material allows higher frequency operation and lower power requirements. Therefore, InP is widely being used for the manufacture of microwave devices, high-frequency devices and optoelectronic integrated circuits (OEICs) which are indispensable for wireless technology, satellite communications^[1—3]. Although n-type and p-type InP can meet actual needs, semi-insulating InP substrates remain to be improved due to their poor uniformity and consistency. For this reason, several possible approaches have been reported to the preparation of SI InP by wafer annealing under different conditions^[4—9].     

具有多个参数扰动的随机恒化器模型研究

考虑了一类营养的输入浓度和稀释率同时受到白噪声干扰的随机恒化器模型.首先证明了模型正解的全局存在唯一性;其次通过构造Lyapunov函数的方法研究了在不同条件下随机模型的解围绕其相应确定性系统的正平衡点和绝灭平衡点的振荡行为;最后通过数值仿真验证了所得结论的正确性.     

大型板装配拼接节点试验研究

提出了装配整体式钢筋混凝土大型板一种新的横向拼接节点构造,对9根新型横向连接预制板试件进行试验研究与承载力分析,量测并分析试件的荷载、挠度及应变,观测试件的裂缝发展情况和破坏过程.试件的破坏形态包括弯曲破坏、受剪破坏及轴向拉伸破坏等形式.试验表明,该新型横向连接节点连接可靠,具有良好的承载能力和延性.对新型横向连接节点...     

Diagnosis of Multiple Fixture Faults in Multiple-Station Manufacturing Processes Based on State Space Approach

Dimensional quality is one of the most critical challenges in industries, which uses the multistage manufacturing process (MMP) such as assembly and machining for automotive and aerospace industries.According to investigations, fixture faults accounted for 72% of all the dimensional faults. Previous studies focused on only one fault or multiple faults occurred in one station or one fault in multiple stations, but these cases rarely appear in the real manufacturing. This paper presents a method for diagnosis of multiple fixture faults in the multi-station manufacturing process. The proposed method is based on the state space model of the MMP processes, which carries the information of the fixture layout geometry and sensor position. To identify the root cause, three continuous steps were used: a) development of the state space model and the construction of the statistics variables on offline mode, b) measurement of the coordinate measuring machines data on online mode and calculation of the statistics variables, and c) diagnostic algorithm for identifying the root cause. The presented paper integrates the state space model of the manufacturing processes and hypothesis test considering the impact of the measure noises. A case study verifies the proposed method.     

用并矢格林函数方法求解四层丛林模型的场:Ⅱ应用部分(英文)

本文用矢格林函数方法求解了在四层丛林模型中任意极化的电偶极子的电磁场。给出了侧面波决定的远区场及使该场有最大激励的偶极子的最大入射角。     

基于SIR和UIR的双通带带通滤波器的设计

基于λ/2的阶跃阻抗谐振器(SIR)和均匀阻抗谐振器(UIR)设计了一个结构紧凑的双通带带通滤波器,并给出了滤波器的等效电路模型.调整SIR和UIR的长度和阻抗实现双通带,折叠SIR和UIR使得滤波器的结构更加紧凑.经仿真优化及实物制作,测试结果表明,该滤波器工作在2.4GHz和5.59GHz,插入损耗分别为1.69dB和4.33dB.该滤波器具有以下优点:尺寸小,结构紧凑,易于设计和制作,可广泛应用于射频前端.     

矩阵乘法的极大子群

数域K上n×n矩阵的全体Mn(K)在乘法运算下封闭.首先刻划Mn(K)中矩阵A是群矩阵的特征,进而刻划Mn(K)在乘法运算下的所有极大子群.