碳/碳复合材料表面改性及其生物响应特性

碳/碳复合材料继承了碳材料固有的生物相容性,它具有优异的力学性能,特别是它的弹性模量与人骨相当,是一种具有潜力的骨修复和替代生物材料.但是由于碳/碳复合材料为生物惰性材料,其与骨组织表面仅仅是机械结合,通过表面改性,可在其表面构筑生物活性涂层以提高其生物活性和减少碳颗粒的释放.本文在综述了碳/碳复合材料表面生物活性涂层制备方法及其生物学响应特性的基础上,分析了目前研究中存在的问题,提出一些解决的办法,并展望了其发展前景.     

碳／碳复合材料的发展前景

论述了国内外碳／碳复合材料（Ｃ／Ｃ）的优越性、性能、工艺、应用及其前景。     

碳／碳复合材料及其在航空上的应用前景

本文分四部分论述了碳／碳（以下称为Ｃ／Ｃ）复合材料及其发展形势：Ｃ／Ｃ复合材料的现状，工艺，性能及应用：Ｃ／Ｃ复合材料的制造工艺及其发展趋势：Ｃ／Ｃ复合材料的抗氧化保护涂层；Ｃ／Ｃ复合材料在航空上的应用前景。最后指出：Ｃ／Ｃ复合将逐渐由短期应用走向长期应用，制造工艺将由长时间走向短时间，抗氧化保护涂层将由单纯的表面涂覆走向立体多重涂覆，成本将大大降低，主要应用范围将逐渐由航天技术的结构功能材料发展     

碳／碳复合材料中的立方石墨初探

在研究碳／碳复合材料的晶体结构中发现了非六方石墨结构，通过对比Ｘ射线衍射的特征峰、衍射角、衍射强度及碳／碳复合材料的理论密度，初步证实了非六方石墨即为立方石墨，并说明了立方石墨的存在，可使碳／碳复合材料的石墨化程度提高，致密性增加。     

生物医用多孔金属材料的研究进展

本文综述了生物医用多孔金属材料在制备工艺，力学性能，耐蚀性及生物相容性方面的研究进展。作为一种新型的硬组织修复材料，生物医用多孔金属材料以其优良的生物相容性在矫形外科，牙科等医疗领域有广阔的应用前景。     

碳/碳复合材料内耗行为研究

碳／碳复合材料的内耗是材料内部各种结构因素共同作用的结果。通过分析碳纤维、热解碳基体及纤维／基体界面对碳／碳复合材料内耗特征的影响规律与机抽,对碳／碳复合材料的内耗行为进行了研究。     

碳／碳材料快速CVD工艺结构性能及应用研究

首次提出了快速化学气相沉积碳／碳复合材料的工艺模型，设计出制备碳／碳复合材料的新工艺－－快速定向扩散法。这种方法能省去常规制备方法中需多次３人反复进行的中间机加工、高温热工处理工序，缩短制备周期约达１／４，制备的碳／碳复合材料的密度达到１．８５以上。弯曲强度、弯曲模量分别高达２４５ＭＰａ、４９ＧＰａ，氧化起始点将近提高３００℃。深入研究了快速化学气相沉积碳／碳复合材料的组织特征，揭示了工艺、性能和     

聚氨酯/碳纳米纤维复合材料的结构和抗凝血性能

分别采用溶液共混和熔融共混的方法制备出聚氯酯／碳纳米纤维复合材料，研究了碳纳米纤维对聚氯酯的热行为和表面微观化学组成的影响，并观察和测定了血小板在复合材料表面的粘附以及血液中血红蛋白浓度、纤维蛋白原浓度的变化，分析了碳纳米纤维对聚氯酯血液相容性的影响．结果表明，引入碳纳米纤维后，聚氯酯复合材料的表面氧含量有不同程度的提高，玻璃化转变温度及熔融温度都发生了改变；血小板在复合材料表面的粘附受到明显的抑制；经血泵循环4h后，在与聚氯酯复合材料表面接触的血液中，血红蛋白和纤维蛋白原浓度的变化相对减小；复合材料的血液相容性提高．     

碳／碳复合材料飞机刹车盘的研制

探索了碳／碳复合飞机刹车材料的制备技术。文中对总体方案进行了细致的分析，确定了稳定可靠的工艺参数，用快速定向扩散新技术通过化学气相沉积法研制了碳／碳复合材料飞机刹车盘。试验表明该复合材料刹车盘只有良好的耐磨损性能。     

碳／碳复合材料抗氧化行为的研究进展

综述了碳／碳复合材料抗氧化行为的研究现状，介绍了几种对碳／碳复合材料氧化机理的认识和建立的模型，并分析了温度，环境等影响氧化机制的因素，从基体改性和外部涂覆等角度总结了近年来抗氧化举措的研究结果，并展望了耐高温抗氧化涂层的研究方向。     

Thermophysical properties of some key solids: An update

In 1985, the CODATA Bulletin published a Report of its Task Group on Thermophysical Properties of Solids which analyzed available data on, and gave recommended values for, the heat capacity of Cu, Fe, W, and Al₂O₃, the thermal expansion of Cu, Si, W, and Al₂O₃, the electrical resistivity of Cu, Fe, Pt, and W, the thermal conductivity of Al, Cu, Fe, and W, and the absolute thermopower of Pb, Cu, Pt, and W. The analysts for the different properties were R. B. Castanet, S. J. Collocott, P. D. Desai, C. Y. Ho, J. G. Hust, R. B. Roberts, C. A. Swenson, and G. K. White. The present paper is an updated version of the earlier report and includes more recent data which change some of the recommended values. notably the heat capacity of Cu and W and the thermal expansion of Si and W.     

Age and pedestrian injury severity in motor-vehicle crashes: a heteroskedastic logit analysis

This research explores the injury severity of pedestrians in motor-vehicle crashes. It is hypothesized that the variance of unobserved pedestrian characteristics increases with age. In response, a heteroskedastic generalized extreme value model is used. The analysis links explanatory factors with four injury outcomes: fatal, incapacitating, non-incapacitating, and possible or no injury. Police-reported crash data between 1997 and 2000 from North Carolina, USA, are used. The results show that pedestrian age induces heteroskedasticity which affects the probability of fatal injury. The effect grows more pronounced with increasing age past 65. The heteroskedastic model provides a better fit than the multinomial logit model. Notable factors increasing the probability of fatal pedestrian injury: increasing pedestrian age, male driver, intoxicated driver (2.7 times greater probability of fatality), traffic sign, commercial area, darkness with or without streetlights (2-4 times greater probability of fatality), sport-utility vehicle, truck, freeway, two-way divided roadway, speeding-involved, off roadway, motorist turning or backing, both driver and pedestrian at fault, and pedestrian only at fault. Conversely, the probability of a fatal injury decreased: with increasing driver age, during the PM traffic peak, with traffic signal control, in inclement weather, on a curved roadway, at a crosswalk, and when walking along roadway.     

纳米技术：新世纪的机遇和挑战

纳米技术是二十一世纪最具发展前景的领域,当前,在全球范围内,一个以纳米材料,纳米电子学和纳米医疗为核心的高科技时代已经来临,很多产业都将因纳米技术的发展而得益,如通讯、计算机、医疗、化工、材料、能源、飞机、汽车、航天、环保和机械制造等。而且十分明显的是,几乎所有的方面都涉及或依赖于真空科学与技术。     

An Approach to Calculate Thermodynamic Properties of Mixtures Including Propane, <Emphasis Type="Italic">n</Emphasis>-Butane,and Isobutane

This paper discusses a mathematical model for computing the thermodynamic properties of propane, n-butane, isobutane, and their mixtures, in the fluid phase using a method based upon statistical chain theory. The constants necessary for computations such as the characteristic temperatures of rotation, electronic state, etc. and the moments of inertia are obtained analytically applying a knowledge of the atomic structure of the molecule. The paper presents a procedure for calculating thermodynamic properties such as pressure, speed of sound, the Joule-Thomson coefficient, compressibility, enthalpy, and thermal expansion coefficient. This paper will discuss, for the first time, the application of statistical chain theory for accurate properties of binary and ternary mixtures including propane, n-butane, and isobutane, in their entire fluid phases. To calculate the thermodynamic properties of Lennard-Jones chains, the Liu-Li-Lu model has been used. The thermodynamic properties of the hydrocarbon mixtures are obtained using the one-fluid theory. Paper presented at the Fifteenth Symposium on Theremophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Hybrid features-enabled dragon deep belief neural network for activity recognition

Activity recognition is a challenging task in computer vision that finds widespread applications in various fields, such as motion capture, video retrieval, security, and video surveillance. The objective of this work is to present a technique for recognizing human activities in videos using Dragon Deep Belief Network (DDBN) and hybrid features, which comprises of features like shape, coverage factor, and Space-Time Interest (STI) points. Initially, the keyframes from the input video sequence are extracted using Structural Similarity (SSIM) measure. Then, the features, such as shape, coverage factor, and STI points, are extracted from the keyframes. Based on the feature vector extracted, the proposed DDBN classifier, which is designed by the effective combination of DBN and Dragonfly Algorithm (DA), a classification on human activities, such as walk, bend, etc. in videos. In DDBN, the weights in the network are selected optimally using DA. The weight update using the DA for each incoming feature improves the performance of the DDBN classifier. Further it improves the accuracy in classification of actions. The proposed DDBN classifier is experimented using KTH and Weizmann datasets based on three evaluation parameters, such as accuracy, sensitivity, and specificity. From the performance evaluation, the proposed DDBN classifier could attain better performance with the probability of 98.5% accuracy, 0.96 sensitivity, and 0.959 specificity, respectively.     

Pressure drop in riser and evaporator in an advanced two-phase thermosyphon loop

This study presents an experimental investigation of pressure drop in the evaporators and the riser of an advanced thermosyphon loop. The thermosyphon was designed for the cooling of three parallel high heat flux electronic components. The tested evaporators were made from small blocks of copper in which 7, 5, 4, 3, 2, 1 vertical channels with the diameters of 1.1, 1.5, 1.9, 2.5, 3.5 and 6 mm, respectively, and a length of 14.6 mm were drilled. Tests were done with isobutane at heat fluxes ranging between 22.4 and 303 kW/m². For prediction of the pressure drop, in the riser, different combinations of frictional pressure drop and void fraction correlations were tested. Regarding the evaporator a simple correlation based on a homogeneous model [M.B. Bowers, I. Mudawar, Two-phase electronic cooling using mini-channel and macro-channel heat-sinks—part II, flow rate and pressure drop constraints, ASME J Electron Packaging 116 (1994) 298–305. [1]] has been used to predict the pressure drop.     

材料医学和医学材料

临床医学和生物材料的蓬勃发展, 促进了多种疾病的诊断成像、有效治疗和精准诊疗。材料与医学交叉学科(简称“材料医学”)的发展旨在克服传统临床医学面临的主要障碍和挑战, 如系统性毒性、生物利用度差、靶向部位特异性低、诊断/治疗效果不理想等。本文系统地阐述了近年来各种医学材料在疾病诊断、治疗和诊疗方面的应用进展, 特别是纳米医学材料的研究进展。首先, 重点讨论癌症治疗领域的生物医学成像(如光学成像、磁共振成像、超声成像、计算机断层成像等)和治疗策略(如光热治疗、动力学治疗、免疫治疗、协同治疗等)。此外, 我们还重点介绍了医学材料对骨组织工程、呼吸系统、中枢神经系统等疾病的诊断和治疗的最新进展, 并重点阐述了用于生物传感和抗微生物等其他代表性生物医学领域的医学材料。最后, 我们讨论了这些独特的医学材料在实际临床转化和应用中所面临的挑战和未来的机遇, 以促进其早日实现临床转化, 推动医学进步和造福患者。     

Studies on Mechanical, Friction, and Wear Characteristics of Kevlar and Glass Fiber-Reinforced Friction Materials

Asbestos possesses properties that are ideally suitable for use as a friction material in automotive and a number of other applications. Animal and human studies carried out since the early 1900s have established that asbestos is carcinogenic and that exposure to especially asbestos dust causes a large number of diseases. Realizing the health hazards posed by asbestos, many countries started phasing out asbestos from all asbestos-containing products since the 1980s. Some of them imposed a total ban in the 1990s on the use of asbestos-containing friction products. This situation forced many manufacturers to look for alternatives to asbestos. But the efforts have only been partly successful. The search is, therefore, still on to find suitable substitutes for asbestos. Though steel wool, Kevlar, glass, and a number of other mineral fibers have been tried out on an experimental basis over the last two decades, glass and Kevlar fibers, in particular, have shown promise as potential substitutes for asbestos. These days, therefore, studies on polymer-based friction materials reinforced with glass, Kevlar, and ceramic fibers are being pursued with much fervor. However, conflicting views are prevailing even today as to the suitability of asbestos-free composites for automotive applications and freedom from the concomitant health risks posed by them. In the present work, therefore, phenolic resin matrix samples reinforced with different amounts of glass and Kevlar fibers were produced and characterized for their mechanical, physical, friction, and wear properties to assess their suitability for light passenger car applications. The study establishes that composites based on glass and Kevlar fibers show good mechanical, physical, friction, and wear characteristics, enhancing thereby their suitability for automotive applications. The property improvements achieved are correlated to the composition, microstructure, and the changes taking place on the surface of the friction composites.     

多波束测深系统多子阵检测法的改进及其性能分析

多波束测深系统中,相位检测法是实现超宽覆盖测量的关键技术之一。分析了分裂子阵相位检测法和多子阵检测法,并基于对子阵结构的分析,改进了多子阵检测法,给出了多子阵检测法输出信噪比的表达式,讨论了子阵结构对输出信噪比的影响,在理论分析基础上选择了三种子阵结构对海上试验数据进行了处理,验证了分析结果。处理结果表明,在优化参数基础上,多子阵检测法不但可实现多波束测深系统的超宽覆盖,而且可改善系统对海底的检测性能。     

Processing issues,machining, and applications of aluminum metal matrix composites

Aluminum metal matrix composites (AMMCs) used in different industries from automotive to aerospace for specific purposes. Many problems hinder the full-scale industrialization of AMMCs but the main problems include wettability, particle distribution, porosity, and chemical reaction. These problems have explicit effects on mechanical, wear, and corrosion resistance properties of the composite materials. Therefore, it is essential to cope up with these problems for better quality of AMMCs. This paper focuses on issues related to AMMCs fabrication, corrosion resistance, wear resistance, machining parameter optimization, and chip analysis of AMMCs. Literature provides a guideline to researchers about present scenario of AMMC fabrication using stir casting process. Moreover, paper presents properties and applications of AMMCs.