Investigation of machining and wear performance of various diamond micro-grinding tools

The International Journal of Advanced Manufacturing Technology - The wear of micro-grinding tools less than 1 mm in diameter is crucial for achieving acceptable surface quality and accurate...     

SDN智能管控编排系统技术方案研究

随着用户对网络提出更为苛刻的服务质量要求,运营商着力进行各专业网络的智能化改造建设。首先,简单介绍了产业界各专业网络软件定义网络（software defined network,SDN）改造建设现状,并对改造过程中存在的问题进行了分析;然后,提出了SDN智能管控编排系统方案,以满足用户对跨专业业务端到端自动开通的需求,并在网络层面实现资源数据的智能分析,提升运维效率;最后,介绍了在提出架构下的专线业务开通流程和实时告警流程与实践。     

化学机械磨削技术研究现状与展望

化学机械磨削能通过化学机械协同过程实现单晶硅、石英玻璃等硬脆材料的超精密高质低损加工,被广泛应用于半导体以及光学等领域器件的平坦化加工。在综述化学机械磨削技术材料去除机理、磨削工艺以及复合加工工艺等方面研究现状的基础上,对上述研究现阶段存在的问题进行了分析讨论。分析表明,从固固相化学反应机制和化学机械协同效应角度揭示化学机械磨削机理,有助于从材料去除机理、磨具结构设计以及复合加工工艺开发等角度创新得到提高该技术加工效率的可行性方法。最后,对化学机械磨削技术在多样化加工对象、较复杂结构加工、多能场复合加工工艺以及智能数据库开发等方向的发展进行了展望。     

低比转速压气机轮毂轮缘型线多目标优化设计

对电动增压器用低比转速离心压气机轮毂轮缘进行优化设计。采用NUMECA/FINE Design 3D对压气机进行几何参数化,生成数据库样本,利用人工神经网络和遗传算法对轮毂轮缘型线进行优化,并进行流场分析。仿真结果表明,在设计转速为40000 r/min时,优化后设计点压比和效率分别提高6.59%和3.73%。     

侧边研磨应力双折射型保偏光纤光栅实验

利用自制研磨机侧边研磨了应力双折射型偏振保持布拉格光纤光栅(PMFBG),并对研磨过程中的透射光谱与反射光谱进行了监测.研磨过程中造成的功率损耗小于0.6dB,PMFBG的两个布拉格波长均发生了漂移,且两者的间距有变小的趋势.通过曲线拟合得到了两个偏振态的有效折射率随研磨深度的变化规律,并分析得出:光纤芯子中心的应力双...     

Adaptive flow optimization of a turbocharger compressor to improve engine low speed performance

To improve the engine overall performance, an adaptive flow optimization procedure is proposed in this paper to synthesize turbocharger compressor optimum designs. Two objective functions are involved in the adaptive optimization. They are the traditional compressor design and the compressor design with consideration of improving engine overall performance. The two-step decomposition approach is chosen to generate optimum designs. The optimized designs not only satisfy turbomachinery and engine constraints but also have optimum objective function values in the two fields. Performance sensitivity analysis of compressor main design variables is performed for the flow optimization design process. A centrifugal compressor is redesigned for a turbocharged gasoline engine, as an example, based on the adaptive flow optimization process. The calculating results show a more than 5% increase of isentropic efficiency in comparison with the base line compressor, resulting in a more than 19% increase of engine torque at low speed conditions.     

突发事件泄漏石油类污染物在水环境中迁移转化研究进展

突发事件泄漏的石油类污染物在水体中的迁移转化规律一直是环境水力学研究的难点.根据石油类污染物的物理、化学特征,针对其在水体中不同阶段的运动动力学特征,分别从油膜在水体表层的扩展迁移过程、水体表层油膜的风化过程、油膜污染物向下层水体的扩散过程、水体中石油类污染物的迁移转化过程、石油类污染物的迁移转化过程物理试验、常用溢油...     

猴头菇多糖对免疫应激小鼠胸腺和脾脏显微结构、免疫功能及细胞增殖和凋亡的影响

目的 研究猴头菇多糖对脂多糖（LPS）诱导免疫应激小鼠胸腺和脾脏显微结构、细胞因子分泌、抗氧化功能及细胞增殖和凋亡的影响,为猴头菇多糖在缓解应激状态中的应用提供参考。方法 选用12周龄雄性昆明小鼠50只,随机分为对照组、模型组和试验Ⅰ-Ⅲ组（n=10）。除对照组腹腔注射生理盐水外,其余4组在试验结束前3 d腹腔注射0.6 mL/kg/d的LPS（1次/d）。试验Ⅰ、Ⅱ、Ⅲ组分别灌胃80、160、320 mg/kg的猴头菇多糖,持续2周。测定胸腺和脾脏促炎细胞因子水平、抗氧化功能及细胞增殖和凋亡基因表达,并进行显微结构观察分析。结果 与对照组相比,模型组胸腺和脾脏中白细胞介素1β（IL-1β）、白细胞介素4（IL-4）和干扰素γ（IFN-γ）水平显著或极显著升高（P<0.05或P<0.01）,总超氧化物歧化酶（T-SOD）和总抗氧化能力（T-AOC）活性显著降低（P<0.05）、谷胱甘肽过氧化物酶（GSH-Px）含量也显著降低（P<0.05）,丙二醛（MDA）含量显著升高（P<0.05）,脾脏增殖细胞核抗原（PCNA）mRNA表达量显著降低（P<0.05）,半胱氨酸蛋白酶-3（Caspase-3）mRNA表达量显著增加（P<0.05）。与模型组相比,试验Ⅲ组小鼠胸腺和脾脏IL-1β、IL-4和IFN-γ水平显著或极显著降低（P<0.05或P<0.01）,T-SOD、T-AOC和GSH-Px的活性或含量均显著升高（P<0.05）、MDA含量和Caspase-3 mRNA表达量显著降低（P<0.05）。组织学观测发现,试验Ⅲ组小鼠胸腺和脾脏显微结构与模型组相比明显改善,胸腺皮质厚度增加（P<0.01）,脾小结和动脉周围淋巴鞘厚度降低（P<0.05或P<0.01）。结论 补充320 mg/kg猴头菇多糖能够明显改善免疫应激对小鼠胸腺和脾脏显微结构的损伤,抑制免疫应激诱导的促炎细胞因子分泌和细胞凋亡基因表达,增强抗氧化酶活性。     

Simulated effects of flow rate on phosphate retention in soils

Phosphate in waste water disposed in the field can be partially or wholly retained in soil, eliminating ground water pollution. The retention ability of soil is affected by many factors, such as soil pH, minerals, structure, water content, solute concentration, solution pH, etc. The flow rate of waste water within a soil profile may be an important factor as well. It is the purpose of this paper to simulate different flow patterns in soils and their effect on the renovation of waste water by soils. A system of partial differential equations, including water flow and phosphate transport equations with a P-soil reaction model, were solved simultaneously to simulate the saturated or unsaturated flow of phosphate solution and its reactions in soils. Euler implicit and general explicit finite difference methods were applied to solve these equations. The results indicate that phosphate retention by soils from a finite quantity of waste effluent could be increased by decreasing the flow rate. An on-and-off intermittent disposal of waste water would also increase the retention capacity when compared to continuous flooding of the same amount of effluent. The main cause of these effects is the difference of reaction time of phosphate with soils.     

低压配电网并联电容器的无功补偿优化算法

针对低压配电网电压低、电流大、线损高的特点,提出了一种以配电网线损最小为目标的电容器无功补偿的优化算法,进而有效确定配电线路中补偿电容器的安装位置和最佳补偿容量,与传统的近似算法和2n/(2n+1) 算法相比,其克服了不足,并通过实际低压配电网的时间证明其具有的经济性和有效性,为其应用提供了理论依据和实践参考。