纤维铝合金层板的研究进展

纤维铝合金层板是由铝合金和纤维增强复合材料组成的一种混杂结构材料,是一种新型的航空结构材料,广泛应用于飞机较为关键的疲劳结构件上.主要介绍了ARALL和GLARE两种纤维铝合金层板的疲劳性能、拉伸性能、抗损伤性能的研究现状,并进一步提出了今后的研究方向和工作重点.     

泡沫玻璃强化技术的研究进展

改善泡沫玻璃力学性能直接、有效的手段是对其进行增强处理。评述了泡沫玻璃的微晶化增强、纤维增强、高密度增强等技术的优势与不足,指出了它们亟待解决的技术难点,总结了泡沫玻璃几种新强化技术的发展状况,深入探讨了目前泡沫玻璃增强技术中存在的问题和进一步研究的方向。     

剑麻纤维增强聚合物基复合材料

剑麻是一种价廉质轻、具有高比强度和比模量的天然纤维,可用作聚合物复合材料的增强材料。本文作者总结了近年来剑麻/聚合物复合材料的研究进展,介绍了剑麻的结构与性能、表面改性方法及其复合材料力学性能的影响因素等,并对今后的研究作了进一步的展望。     

Nicalon碳化硅长纤维增强铝

由聚碳硅烷(PCS)制的长纤维“Nic-alon”是一种主要的增强纤维。用它制的纤维增强金属(FRM)除了与FRP一样具有重量轻、高强度、高模量的特性外,还有使用范围宽得多的特点,其拉伸强度为1.47GPa,能耐450℃高温。 1987年开始在市场上大量供应由Nical-on和铝制的坯丝,预期这一产品在日本、美国和欧洲将获得广泛应用。以下进一步介绍这种新材料。     

磁控溅射中旋转阴极的对角效应及其解决途径

对角效应是一种存在于磁控溅射中,由于阳极的不对称分布而引起的一种不对称刻蚀的现象,表现为靠近阳极的一侧溅射跑道沿着霍尔电流方向的转角刻蚀明显增强,而另一侧对应转角刻蚀相对较弱,如为双靶时,表现为沿对角线方向刻蚀增强的现象,导致靶材的不均匀刻蚀及靶材利用率降低.文章研究了这种现象,对其成因进行了分析,并进一步阐明了如何避...     

一种基于椭圆曲线安全电子邮件的研究与构建

本文从电子邮件传输过程的安全角度出发,分析了目前广泛应用的安全电子邮件产品存在的不足,提出了一种采用椭圆曲线来实现密钥交换、数字签名、加/解密的方案,从而进一步增强了电子邮件的机密性、完整性和不可否认性。     

真空隔热屏机理和性能的研究

在现今已知绝热材料中，真空隔热屏的导热系数是最低的一种。作者在文中就真空隔热屏的机理作了进一步的探索，并提出增强真空隔热屏的绝热性能的七点措施，供读者参考和借鉴。     

制备工艺对铝基复合材料增强体颗粒分布均匀性的影响

采用高能球磨法混料和低温快速热挤压相结合的粉末冶金工艺制备了SiCp/6066Al复合材料,研究了制备工艺对增强体颗粒分布均匀性的影响.结果表明:高能球磨法混料是显著改善增强体颗粒形貌、细化增强体颗粒粒度,在基体更小的微区域中实现增强体颗粒数量分布均匀性的最有效混料方法;低温快速热挤压利用基体的较低塑性和强大物理变形量使增强体颗粒进一步细化,得到的细小等轴颗粒更易随着基体的塑性流动而呈弥散均匀分布,进一步改善或消除微区域内增强体颗粒的偏聚或尽可能降低偏聚的程度.两种方法相结合是实现增强体颗粒微观分布均匀性的最有效方法.     

聚醚醚酮改性研究进展

聚醚醚酮(PEEK)作为一种新型高性能热塑性工程塑料,在许多工程领域有着广泛的应用.采用不同手段增强PEEK,改善其加工性能和力学性能、热性能、摩擦学性能,有利于降低材料成本和进一步拓展应用范围.本文从纤维增强PEEK、颗粒填充PEEK、PEEK表面改性、与聚合物共混等方面综述了PEEK改性研究的进展情况.     

改进的Kullback-Leibler复非负矩阵分解语音增强算法

针对单通道非负矩阵分解语音增强算法忽略相位信息的问题，提出了一种改进的Kullback-Leibler复非负矩阵分解的语音增强算法。该算法考虑到传统非负矩阵分解算法在复频域中增强语音时目标函数的影响，构建了一种适用于复频域的Kullback-Leibler散度下的目标函数，同时采用频谱一致性约束相位谱补偿算法，使其重构出的语音数据相位谱得到进一步的调制。实验结果表明，对于不同的非平稳噪声，所提出的算法在不同信噪比下均取得了较好的语音增强效果，尤其在低信噪比条件下（0 dB以下）语音增强效果较为明显，性能评估指标的增量较高，较好地克服了由传统相位谱补偿算法造成的信源失真率较低的缺点，进一步减少失真，抑制背景噪声，实现语音增强。     

SMA/PA6界面化学反应的流变学测试

采用流变学的方法研究了剪切作用下苯乙烯-马来()酐共聚物(SMA)/尼龙6(PA6)体系的界面化学反应.固定可反应界面面积,从化学反应动力学的角度分析剪切提高界面化学反应速率的原因.研究发现,随着SMA/PA6界面上施加角频率和应变的增大,界面化学反应速率增大,化学反应动力学由一级扩散控制反应向二级化学反应控制转变,表...     

日化品瓶铝箔密封性检测方法及其实验研究

目的 提高日化品瓶铝箔密封性的检测准确率。方法 提出一种日化品瓶铝箔密封性检测方法。通过对铝箔密封后的日化品瓶瓶身施加压力,使瓶身产生一定的形变,基于采集施压过程中日化品瓶产生的反作用力,建立空气泄漏模型对日化品瓶铝箔密封性进行判定。设计日化品瓶铝箔密封性测试实验平台,在不同挤压行程和挤压速度下,对日化品瓶铝箔密封性进行实验。结果 将实验得到的数据代入空气泄漏数学模型后得到的泄漏面积数值与实际数值的最大误差为4.5%。结论 日化品瓶铝箔密封性检测方法操作简单、检测精确,为实际生产过程中对日化品瓶铝箔密封性检测提供了依据。     

Influence of local chemical segregation on the γ′ directional coarsening behavior in single crystal superalloy CMSX-4

The influence of local chemical segregation on the directional coarsening behavior of γ′ phase has been investigated in a nickel-base single crystal superalloy during load-free thermal exposure. It is found that the γ′ phase was preferentially oriented with the direction perpendicular to the dendrite arm growth axis. The chemical gradients caused by local chemical heterogeneities were carefully measured on the scale of a dendrite. It showed that the directions of the γ′ rafting and the chemical gradients are consistent and the magnitude of the chemical gradients affects the rafting rates to some extent. It is suggested that the internal chemical gradients can orientate the development of the γ′ rafts by leading to anisotropy in their growth kinetics during Ostwald ripening. Furthermore, influence of the local chemical segregation on the mechanical properties is also discussed.     

Numerical modelling of fluids mixing,heat transfer and non‐equilibrium redox chemical reactions in fluid‐saturated porous rocks

Non‐equilibrium redox chemical reactions of high orders are ubiquitous in fluid‐saturated porous rocks within the crust of the Earth. The numerical modelling of such high‐order chemical reactions becomes a challenging problem because these chemical reactions are not only produced strong non‐linear source/sink terms for reactive transport equations, but also often coupled with the fluids mixing, heat transfer and reactive mass transport processes. In order to solve this problem effectively and efficiently, it is desirable to reduce the total number of reactive transport equations with strong non‐linear source/sink terms to a minimum in a computational model. For this purpose, the concept of the chemical reaction rate invariant is used to develop a numerical procedure for dealing with fluids mixing, heat transfer and non‐equilibrium redox chemical reactions in fluid‐saturated porous rocks. Using the proposed concept and numerical procedure, only one reactive transport equation, which is used to describe the distribution of the chemical product and has a strong non‐linear source/sink term, needs to be solved for each of the non‐equilibrium redox chemical reactions. The original reactive transport equations of the chemical reactants with strong non‐linear source/sink terms are turned into the conventional mass transport equations of the chemical reaction rate invariants without any non‐linear source/sink terms. A testing example, for some aspects of which the analytical solutions are available, is used to validate the proposed numerical procedure. The related numerical solutions have demonstrated that (1) the proposed numerical procedure is useful and applicable for dealing with the coupled problem between fluids mixing, heat transfer and non‐equilibrium redox chemical reactions of high orders in fluid‐saturated porous rocks; (2) the interaction between the solute diffusion, solute advection and chemical kinetics is an important mechanism to control distribution patterns of chemical products in an ore‐forming process; and (3) if the pore‐fluid pressure gradient is lithostatic, it is difficult for the chemical equilibrium to be attained within permeable cracks and geological faults within the crust of the Earth. Copyright © 2005 John Wiley & Sons, Ltd.     

浅析卫星定位车载终端使用的问题

卫星定位车载终端安装在旅游客车、包车客车、三类以上班线客车和危险货物运输车辆上,能有效监测车辆速度、定位等数据,广泛用于道路交通安全监管,测量的车辆速度、定位等数据已成为有效的监管依据。由于卫星定位车载终端固定安装在车辆上,无法有效监控其工作状态,在使用中存在以下问题：因安装不当、使用不当、数据筛选造成的数据失真;因数据传输间隔不统一、数据丢失造成的传输不规范;因信号干扰、允许误差分布等造成结果不合理使用。在使用中需要加强核查、规范数据传输、合理使用结果,才能保证数据真实、系统稳定、风险可控。     

化学工业园区循环经济标准体系构建研究

构建化学工业园区循环经济标准体系是发展绿色化工的基础性和统领性工作,对于化工产业的发展和循环经济标准化工作深入开展具有重要意义。基于此,依据循环经济理论和化工园区的特点构建化工园区循环经济标准体系框架结构,并以南京化学工业园区为例,建立循环经济标准体系表。     

Chemical source classification in naturally turbulent plumes

The spatiotemporal dynamics of chemical plumes in natural environments imposes complex time-varying responses on chemical detectors, challenging the use of conventional chemical analysis instrumentation, which often relies upon precisely controlled sampling of analytes. Insects take a different approach to this problem, typically exposing their diversity of chemical receptors to the full extent of the space-time dynamics inherent to these environments. Here we adopt a similar approach, by exposing differentially tuned chemosensor arrays to analytes dispersed in naturally turbulent chemical plumes from a point source. We propose a novel sensor preprocessing metric for complex time-varying chemosensor responses, termed sensor variation, which after normalization generates a stable array response fingerprint representative of the analyte generating the response, and is invariant over a range of distances from the source and source volumes. When applied to chemosensor array response time series, the resultant fingerprints are demonstrated to reliably support chemical classification of a group of pure analytes advected from a point source. By comparing classification performance to the same analytes at equivalent concentrations in controlled sampling conditions, we show that chemical source classification can be achieved in turbulent chemical plumes with similar accuracy to controlled experimental conditions.     

Computational simulation of chemical dissolution‐front instability in fluid‐saturated porous media under non‐isothermal conditions

This paper primarily deals with the computational aspects of chemical dissolution‐front instability problems in two‐dimensional fluid‐saturated porous media under non‐isothermal conditions. After the dimensionless governing partial differential equations of the non‐isothermal chemical dissolution‐front instability problem are briefly described, the formulation of a computational procedure, which contains a combination of using the finite difference and finite element method, is derived for simulating the morphological evolution of chemical dissolution fronts in the non‐isothermal chemical dissolution system within two‐dimensional fluid‐saturated porous media. To ensure the correctness and accuracy of the numerical solutions, the proposed computational procedure is verified through comparing the numerical solutions with the analytical solutions for a benchmark problem. As an application example, the verified computational procedure is then used to simulate the morphological evolution of chemical dissolution fronts in the supercritical non‐isothermal chemical dissolution system. The related numerical results have demonstrated the following: (1) the proposed computational procedure can produce accurate numerical solutions for the planar chemical dissolution‐front propagation problem in the non‐isothermal chemical dissolution system consisting of a fluid‐saturated porous medium; (2) the Zhao number has a significant effect not only on the dimensionless propagation speed of the chemical dissolution front but also on the distribution patterns of the dimensionless temperature, dimensionless pore‐fluid pressure, and dimensionless chemical‐species concentration in a non‐isothermal chemical dissolution system; (3) once the finger penetrates the whole computational domain, the dimensionless pore‐fluid pressure decreases drastically in the non‐isothermal chemical dissolution system.     

欧盟化学品安全评估与高关注物质评估

欧盟化学品安全管理制度是全球最为系统完善的管理体系之一。欧盟实施的化学品安全评估是化学品安全管理以及控制和减少有毒有害化学品风险的主要技术手段,而高关注物质评估是按照化学品危害实施化学品分类管理的技术基础。本文就欧盟化学品安全评估程序进行了介绍,并对欧盟高关注物质评估的程序、标准和方法进行了综述,旨在为我国化学品安全管理提供借鉴。     

谈谈危险化工产品包装质量问题

阐述了我国危化品包装现状,提出提高危化品包装质量的若干途径,危化品包装发展的方向的几点建议