CPT管壳在排气炉内炸裂的原因分析

本建立了CPT管壳有限元计算模型，以计算的机械应力和热应力为依据，分析了CPT管壳在排气炉内炸裂的原因，为合理制定在排气过程中升、降温工艺路线，正确设计CPT管壳等提供了参考依据。     

气液管壳式换热器传热管的热力学计算研究

管壳式换热器广泛应用于开发利用工业二次能源、实现余热回收和节能.文中基于光管传热的理论分析建立了换热管的计算模型,分析了单位长度铜管、钢管热流量和总热流量的计算方法,并编制了管壳式换热器传热管设计计算的Matlab程序.通过工程实例计算,验证了计算方法的实用性和可行性,对管壳式换热器设计的后续结构设计和优化提供了数据支撑,亦可为类似传热问题求解提供参考.     

基于Matlab的管壳式换热器分段计算研究

以折流板结构为基础将管壳式换热器分成一定的计算单元,通过对每个分段单元的研究,从流体物性沿壳体方向变化方面来对管壳式换热器进行整体的工艺设计及计算。并且基于微分法,提出了一种较为准确预测出管壳式换热器管、壳侧壁温分布的方法。通过工程案例分析,并将壁温计算结果与HTRI进行对比得出,管、壳程各单元的壁温平均误差分别1.76%和0.94%,该结果也验证了壁温计算方法的可行性。对于传热系数与压降,与 HTRI 对比得出：变物性计算较定物性在精度有一定的提高。同时通过借助Matlab计算机软件编制了一套用于管壳式换热器分段计算及优化设计程序,实现了换热器的精确优化设计的同时也提高了计算效率,变物性的研究理论为高效低能耗换热器的设计提供了思路和方法,具有一定的工程应用价值。     

螺旋线慢波组件管壳精密装配过程的研究

为了实现对螺旋线行波管慢波组件冷弹压装配过程管壳压力和变形量的精密控制,提出了一种新型夹持方案,并对管壳在压装过程中的变形量、应力应变情况进行了研究。根据现有慢波组件装配过程的工艺特点,基于卡爪与压条间的连接条件,分析运动副间隙对管壳变形量精密控制的影响,提出一种姿态确定的精密夹持方法。通过建立管壳的等效受力模型,进行了管壳的变形计算和应力的分析。结果表明,在线弹性范围内,管壳在力作用点处总变形量位移的偏差为0.62%,应力的偏差为9.8%,可知结果具有较高的有效性。对开发新型慢波组件精密压装设备具有一定的应用价值。     

干式螺杆真空泵转子温度场的有限元分析

利用有限元建立了计算干式螺杆真空泵转子温度场的数值方法，考虑了热传导及转子表面与工作介质的对流换热因素对温度场的影响，采用相似准则方程一迪特斯一玻尔特（Dittus-Boelter）公式计算了对流换热系数。计算结果表明：转子温度场由进气端至排气端近似为线性增长，排气端温度约为120℃。随着转子转速降低，排气端温度迅速降低，当转速在2000r／min以下时，转子由进气端至排气端的温度变化在30℃以下。实验结果验证了上述结论，误差在15％以内。本文的研究工作不仅提供了干式螺杆真空泵转子的温度分布，也为进一步研究转子的热变形，合理确定泵腔内各密封间隙提供了理论与实验依据。     

显象管排气台真空系统设计计算

本文依据１４″黑白电视机显象管生产工艺对排气台的技术要求，分析了排气台真空系统的抽气性能．特点和影响抽气的限制因素，并进行了系统设计计算。     

排气消声器声学及阻力特性数值仿真研究

对某一轻型卡车所装配的消声器,利用声学软件SYSNOISE对消声器声学性能进行数值仿真计算;利用计算流体动力学软件FLUENT对消声器的阻力特性进行数值仿真计算。模拟结果清楚地反映了消声器内的流场和声场的情况,结果表明数值方法能准确的模拟排气消声器的性能。通过仿真模拟,综合考虑消声器内部的声学性能和空气动力性能,表明运用数值方法预测排气消声器的阻力及声学性能在工程中是有效的,为消声器的改进设计和优化设计提供了依据。     

管壳式换热器的经济学优化设计

本文对管壳式换热器的火用经济特性进行了分析与计算，对以单位收益火用成本最低为目标的换热器优化设计，给出了适于工程设计的计算方法。     

管壳式换热器的yong经济学优化设计

本文对管壳式换热器的yong经济特性进行了分析与计算，对以单位收益yong成本最低为目标的换热器优化，给出了适于工程设计的计算方法。     

双级G—M型制冷机运行参数对制冷机性能影响研究

在建立了一套使用电磁阀控制G－M型制冷机进，排气的软，硬件控制系统的基础上，成功地控制了双级G－M型制冷机的进，排气动作。在实验的基础上指出，对于G－M型制冷机而言，存在一定的最佳进，排气角度，这个最佳的进，排气角度对于不同的制冷机而言是不同的。并且制冷机性能受频率变化的影响也是非常大的。文章对此进行了初步的分析，为制冷机的理论分析和设计计算提供了有力的实验依据。     

芯片级原子钟的气密性能分析

基于相干布居囚禁(CPT)原理芯片级原子钟(CSAC)原子腔体积小、采用微电子机械系统硅-玻璃键合工艺制造,其气密性是决定CSAC寿命的关键因素。本文提出了"多层缓冲原子腔"方案大幅度提高原子腔的气密性能,从而提高CPT CSAC的稳定性和寿命。建立了一个"毛细管等效气流模型"模拟多层缓冲原子腔的泄漏以分析原子腔的气密性能,应用Matlab仿真对比了单层密封、多层密封、添加保护腔等不同方式下气密性能的改善幅度。仿真结果验证了"多层缓冲原子腔"在提高CPT CSAC物理系统气密性能方面的可行性和有效性,为原子腔的设计提供指导。     

Numerical Simulation and Technological Parameter Optimization for Quenching Process of a Gas Turbine Compressor Disk Based on Metallo-Thermo-Mechanics

Thermal, mechanical and microstructural phenomena are involved in the process of steel quenching. Based on the coupled metallo-thermo-mechanics theory, a calculation model has been developed in this study to simulate the quenching process of a gas turbine compressor disk by finite element method. The thermal physical and mechanical properties were treated as a functions of temperature. Moreover, a series of subroutines were developed on the MARC software platform. Consequently, simulated results on temperature, internal stress and distortion during the quenching were illustrated. With the aid of the simulated results, an optimum quenching scheme was proposed. The quenching process simulated in this study appears to be a promising tool in design of heat-treatment processing parameters for gas turbine compressor disks.     

Mechanical and corrosion properties of P/M-HIP super duplex stainless steel after different industrial heat treatments as used for large components

Abstract

Mechanical tensile and impact toughness tests and critical pitting corrosion temperature (CPT) tests were performed on samples of Duplok 27, a P/M-HIP duplex stainless steel containing copper, after heat treatments simulating industrial heat treatments of large components. It was shown that copper alloying has positive effects on mechanical tensile properties leading to hardening and more uniform deformation. No negative effects of copper alloying on corrosion resistance properties were found. A drastic drop in impact toughness values and CPT of samples cooled at controlled cooling rates is explained by the precipitation of intermetallic secondary phases or their precursors. Lower CPT of a NG-GTAW (narrow gap gas tungsten arc welding) welded joint is explained by the lower level of alloying than that of the base material. The high temperature region of precipitation of intermetallic secondary phases is shifted towards higher temperatures than assumed for Duplok 27 P/M-HIP duplex stainless steel.     

大电机定子复合绝缘材料老化的动态力学分析

对大电机定子环氧云母复合绝缘材料进行了长时间多因子应力老化,采用动态力学分析仪对不同老化阶段的复合绝缘材料进行了动态力学实验,分析了各力学参量与复合绝缘材料老化时间的关系。根据Eyring绝对反应速度理论,推导了复合绝缘材料玻璃化转变活化能的计算公式并计算了不同老化阶段复合绝缘材料的表观活化能。     

Camptothecin in sterically stabilized phospholipid nano-micelles: a novel solvent pH change solubilization method

Camptothecin (CPT) is a topoisomerase I inhibitor that acts against a broad spectrum of cancers. Unfortunately clinical application of CPT is limited by insolubility, instability, and toxicity problems. To circumvent these delivery problems of CPT, we propose biocompatible, targeted sterically stabilized micelles (SSM) as nanocarriers for CPT (CPT-SSM). SSM composed of polyethylene glycol (PEGylated) phospholipids are attractive nanocarriers for CPT delivery because they are sufficiently small to extravasate through the leaky microvasculature of tumor and inflamed tissues for passive targeting. The purpose of this study was to develop a novel method of preparing CPT-SSM based on its pH dependent, reversible carboxylate-lactone conversion chemistry. CPT carboxylate was added to SSM at pH 5 that favored the formation of active but hydrophobic CPT lactone for spontaneous association with SSM. The kinetics of CPT conversion and CPT-SSM formation, and the effect of varying CPT-PEGylated phospholipid molar ratio on CPT-SSM properties and CPT solubilization were evaluated. CPT converted gradually from the carboxylate form to lactone, and CPT-SSM were formed after 12 h incubation. The mean size of CPT-SSM was approximately 14 nm. CPT solubilization (approximately 12 microg/ml) and other CPT-SSM micelle properties did not change significantly with increasing CPT to PEGylated hospholipid molar ratios using this novel method, unlike the coprecipitation/reconstitution technique previously reported. This reproducible CPT solubilization in SSM was attributed to avoidance of drug aggregate formation by this method. The advantages of our solvent pH change method to prepare CPT-SSM support further investigations of this approach to other hydrophobic drugs similar to CPT in chemistry and also CPT molecular solubilization in other nanocarriers.     

GH4169合金高温力学行为本构建模及参数识别

针对涡轮盘用GH4169合金开展了高温下单调拉伸、对称循环及非对称循环的实验工作,结果表明,该材料具有比较明显的循环软化和平均应力松弛特性.采用带Ohno/Wang修正的Chaboche粘塑性理论本构方程,对其表现出的复杂力学现象进行本构建模,介绍了Levenberg-Marquadt非线性优化算法,结合材料实验数据并通过该算法识别了本构方程参数,将本构方程通过用户子程序嵌入到有限元软件ABAQUS中,对GH4169合金的上述实验现象进行了数值模拟,计算曲线与实验曲线取得了较好的一致性.     

聚合物注塑成型内应力数值计算的非线性模型

为了提高注塑内应力计算的可靠性,利用粘弹性力学理论建立了新的注塑制品内应力计算的四元件串联力学模型,并推导了其瞬态粘弹性响应的非线性本构方程.通过求解流动及保压控制方程,得到内应力计算所需的温度场和压力场,利用回归分析得到了聚合物弹性模量和粘壶系数的计算公式.用新模型对PS平板注塑制件脱模前的内应力进行了模拟计算.计算结果与固体高聚物的结构和力学性能的相关研究结论相一致.     

Evaluation of PLGA microspheres as delivery system for antitumor agent-camptothecin

Camptothecin (CPT) and its analogues are a new class of anticancer agents that have been identified over the past several years. Camptothecin exists in two forms depending on the pH: An active lactone form at pH below 5 and an inactive carboxylate form at basic or physiological neutral pH. Poly(lactide-co-glycolide) (PLGA) microspheres have been considered good delivery vehicles for CPT because of acidic microenvironment formed through PLGA degradation. The objective of this study is to investigate antitumor activity of CPT after it is encapsulated in PLGA microspheres. In this study, PLGA microspheres containing various CPT loadings were prepared and characterized. Cytotoxicity of these microspheres to B16 melanoma cells was then evaluated, and uptake of microspheres by B16 cells was also studied. Analysis of drug stability revealed that CPT is released from the microspheres in its active lactone form over the entire release duration. It was also found that there was no interaction between CPT and PLGA matrix within microspheres through Differential Scanning Calorimetry (DSC) and Fourien Transform Infrared Spectroscopy (FT-IR) and hign performance liquid chromatography (HPLC) studies. Cytotoxicity assay showed that CPT encapsulated in PLGA microspheres still retained its antitumor potency. Uptake study revealed quick uptake of the microspheres by B16 cells, which was desirable. It was concluded that PLGA microspheres were suitable delivery vehicles to stabilize and deliver CPT for the treatment of cancer.     

多轴载荷下车轮辐板裂纹扩展特性研究

针对车轮在运行过程中的典型运用工况,采用有限元方法数值模拟了不同运用条件下车轮的机械应力分布,选取辐板最高应力部位作为裂纹的萌生位置。根据线弹性断裂力学理论研究了辐板裂纹在二轴载荷下的应力强度因子和T应力,最后结合Paris疲劳裂纹扩展方程及裂纹扩展门槛值,得到了二轴载荷下辐板表面裂纹的扩展特性和规律。从而得出了二轴载荷条件对辐板表面裂纹扩展的影响。分析结果表明:典型工况下,车轮辐板外侧处于受压状态,内侧处于受拉状态而且变化幅值较大。车轮辐板的内外表面的应力不同,使得辐板同时承受了弯矩,并且弯矩的周向分量和径向分量近乎于正比。由于T应力的影响,车轮辐板裂纹扩展速度比不考虑此应力时的值较为偏低。分析结果对预防车轮疲劳失效、优化车轮设计、保障行车安全,具有重要意义。     

A novel framework based on a data-driven approach for modelling the behaviour of organisms in chemical plume tracing

We propose a data-driven approach for modelling an organism''s behaviour instead of conventional model-based strategies in chemical plume tracing (CPT). CPT models based on this approach show promise in faithfully reproducing organisms’ CPT behaviour. To construct the data-driven CPT model, a training dataset of the odour stimuli input toward the organism is needed, along with an output of the organism’s CPT behaviour. To this end, we constructed a measurement system comprising an array of alcohol sensors for the measurement of the input and a camera for tracking the output in a real scenario. Then, we determined a transfer function describing the input–output relationship as a stochastic process by applying Gaussian process regression, and established the data-driven CPT model based on measurements of the organism’s CPT behaviour. Through CPT experiments in simulations and a real environment, we evaluated the performance of the data-driven CPT model and compared its success rate with those obtained from conventional model-based strategies. As a result, the proposed data-driven CPT model demonstrated a better success rate than those obtained from conventional model-based strategies. Moreover, we considered that the data-driven CPT model could reflect the aspect of an organism’s adaptability that modulated its behaviour with respect to the surrounding environment. However, these useful results came from the CPT experiments conducted in simple settings of simulations and a real environment. If making the condition of the CPT experiments more complex, we confirmed that the data-driven CPT model would be less effective for locating an odour source. In this way, this paper not only poses major contributions toward the development of a novel framework based on a data-driven approach for modelling an organism’s CPT behaviour, but also displays a research limitation of a data-driven approach at this stage.