摘要：目的:建立微植体与牙槽骨即刻加载的有限元模型,模拟临床上即刻加载时颌骨的应力分布,探讨微植体与牙槽骨间的摩擦系数大小和过盈量对界面应力的影响。方法:利用Pro/E和MIMICS等软件建立微植体和牙槽骨的三维实体模型,然后导入有限元计算软件ABAQUS并建立微植体与牙槽骨即刻加载的有限元模型:①在同一个模型上,设置摩擦系数从0开始,依次递增0.1,一直增加到0.5,对这6种不同情况下界面处应力分布进行比较分析。②在同一个模型上分别设置6个不同的过盈量(即0.002,0.004,0.006,0.008,0.010,0.012mm),通过计算得到这6种情况下界面处最大拉、压应力值,然后进行分析。结果:①无摩擦状态时微植体与牙槽骨界面Von-mises应力最大,随着摩擦系数的增大,各点应力均有不同程度的降低,特别是在骨皮质的位置,应力下降比较明显。但是当摩擦系数增大到一定程度(μ=0.3)之后,Von-Mises应力变化均在1%以下。②通过把不同过盈量时所产生的最大拉、压应力和下颌骨的最大载荷极限做对比,所建立的微植体模型最大过盈量为0.010mm。结论:在即刻加载的情况下,增大界面处的摩擦系数能使应力分布有减小的趋势,但一味的想依靠增大表面摩擦系数来减小界面应力的方法是不可取的;计算得到的最大过盈量0.01mm并不理想,通过比较分析得到,对于不同的模型,可能没有一个统一的过盈量设计,应该充分考虑模型接触界面处的特性,利用界面最终的初始应力与骨的破坏强度相当的理论,通过尝试和比较,最终确定合适的过盈量,从而更准确的模拟植入的最初应力状态,建立符合实际情况的有限元计算模型。

摘要：Spawned by fast-paced progress in new materials and integrate circuit technology,the past two decades have witnessed tremendous development of humanoid robots for both scientific and commercial purposes,*** response and daily life *** the root of this trend are the increasing research interests and cooperation opportunities across different laboratories and *** application-driven requirements of high effectiveness and reliability of humanoid robots led intensive research and development in humanoid locomotion and control *** spite of the progress in the area,challenges such as unnatural locomotion control,inefficient multi-motion planning,and relatively slow disturbances recovery set further requirements for the next generation of humanoid ***,the purpose of this work is to review the current development of highly representative bipedal humanoid robots and discuss the potential to move the ideas and models forward from laboratory settings into the real *** this end,we also review the current clinical understanding of the walking and running dynamics to make the robot more human-like.

摘要：香港大学学术库是香港大学的机构知识库,是响应大学知识交流政策而建立的知识管理系统。凭借丰富的数据来源以及合理的设计机制,学术库已成为颇具影响力的香港大学人才和科研成果的展示平台,成为校内外学术交流的中心,为学术评估和声誉管理提供了基础。

摘要：在中国和印度边远地区，治疗心血管病的经济负担十分沉重，但是这些地区经济落后，医疗保健资源有限。该研究旨在设计和评估由社区医护人员（community health workers，CHW）实施，

摘要：地壳不同深度上的岩石物理性质的差异决定了在垂向上的构造变形呈现不同构造样式.依据地壳内主导变形机制的差异,划分出不同的构造层次,有助于更好地解析出露地质体的构造演化.滇藏怒江峡谷区具有高差大,河流切割地壳深度大,以及在强烈的变形下不同地壳层次的岩石得以出露等独特特征,因此是地壳变形层次研究的理想区域.本文通过对怒江流域察瓦龙至福贡区段的详细区域地质考察和构造变形分析,识别出地壳深层次到浅层次的不同构造变形样式.其中,深层次的构造样式以流动构造变形为主,主要出露于马吉地区.韧性变形在整个研究区广泛出露.高黎贡右行走滑剪切带和普拉底-松塔左行走滑剪切带分别出露在马吉南北区域.以相似褶皱和近直立密集劈理为特征的构造变形样式发育在普拉底以北.脆性断裂,为浅层次变形样式,叠加改造了较深层次变形,在整个研究区都有广泛发育.因此,研究区的主要构造样式由深至浅可划分为流变构造、韧性剪切构造、相似褶皱和脆性断裂构造4个构造层次.4个构造层次不同变形样式的发育均与北东东-南西西向挤压应力场有关.结合热史演化和区域构造特征,滇藏怒江峡谷区不同深度层次构造样式的发育与中新世(21Ma)以来地壳差异性隆起或者剥露有密切的关系.

摘要：为了考察气提式曝气增氧装置在海水养殖水池内的性能表现和溶氧扩散分布规律,自行设计了一种气提式曝气除沫装置,并安装于海水养殖生产车间水池内运行,通过定时定点取样测定池水中的溶解氧浓度,分析该装置运行时养殖池内溶解氧的分布状态,进而确定该装置增氧的性能指标。结果表明:安装自行设计的气提式曝气除沫装置后,通过实际测试,氧转移系数(K_(La(20)))为0.77h^(-1),氧转移效率(E_A)为5.20%,曝气动力效率(E_p,以O_2计)最高可达4.33 kg/(kW·h);经测定,在养殖水池内各个取样点溶解氧分布均匀,溶解氧浓度同步增加。研究表明,本研究中设计的曝气装置及其布置形式因省去动力循环能耗,曝气动力效率显著提高。

摘要：文章讨论了VISION地震数据采集系统中用于均衡补偿高频分量的预增强滤波放大电路的工作原理，分析研究其传输特性，并对其电路的设计特点进行了相应的描述。有关内容对量化前频谱整形均衡器的设计具有一定的参考价值。

摘要：It is a long-standing challenge to search for metallic glasses(MGs)with optimal combinations of glassforming ability(GFA),strength and toughness in the vast compositional *** taking into account both recently developed ellipse criterion and temperature-based GFA criterion,here we established quantitative correlations among compositions,elastic constants,GFA and mechanical properties of MGs,which enable to predict the GFA,fracture strength and fracture surface simultaneously in advance once the compositions of MGs are *** data confirm the validity of this approach in ***,a strategy for designing MGs with optimal combinations of strength,toughness and GFA is proposed,which allows for high-throughput discovering glass formers with excellent mechanical properties.

摘要：The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic *** this problem,a theoretical fatigue model is proposed in this study,the possible applications have also been *** results would be introduced in two serial papers,in which the first paper focuses on the model building and the applications on fatigue strength prediction;the second paper put emphasis on the influencing factors of the model parameters and the applications on fatigue strength *** this first paper,a theoretical model is proposed considering both the strength and plastic restrictions of fatigue *** the model builds up a brief relationship among yield strength(Y),tensile strength(T)and fatigue strength(F),it is named as the Y-T-F *** the verification with fatigue strength data covering various kinds of metallic materials and loading conditions,this Y-T-F model exhibits both generality and *** the Y-T-F model,the efficient fatigue strength prediction could be conducted by brief linear fitting and calculation,just through yield strength,tensile strength and several known fatigue strength ***,through its deduced Y-F model,the analytical formula of fatigue strength continuously changing with materials strengthening can be obtained,as well as the maximum value of fatigue strength and corresponding critical yield *** summary,the Y-T-F model would be useful for reducing the fatigue tests,thus providing new possibilities on the efficient anti-fatigue design and selection of metallic materials.