科创中国

根据超声波在混凝土介质中传播的声速、首波幅值、波形,分析了大尺寸混凝土试样的内部缺陷和均匀性,并对其弹性模量、衰减系数、松弛时间等动态参数进行求解.为了与超声波检测结果对比,采用改进的Hopkinson压杆技术对同配比的圆柱形混凝土试样进行实验研究来测定其相应动态参数,并对比分析了两种方法的不同之处.实验结果表明:两种方法测定的动态弹性模量基本一致;HPB试验测得的衰减系数比超声波试验测得的值大,这说明HPB试验中存在动态损伤的影响;HPB试验测得的松弛时间比超声波测得的增加了近一倍,这表明了在高应变率下,混凝土试样的脆性得到了明显的增加.试验数据可以为工程应用提供借鉴.

望江楼以较大尺度的混凝土拱形悬挑结构与场地内的高架步道、防汛墙、美术馆广场以及最重要的景观-东南面宽阔的黄浦江取得空间上的对话,这个建筑因为适应了新的环境因素而植入场地.拱形结构除了可以有效地避开既有的二级防汛墙,更能建立起场所的景观方向感以及与人身体的关系.

工业用线钳表面抛光机床是一种新型的磨削装置,其磨削过程用液压系统控制,从而实现大批量加工.该文首先利用三维设计软件UG NX3进行液压系统结构设计,再从结构方案的确定、主要部件的设计计算以及系统原理图的确定等几个方面对工业用线钳表面抛光机床液压系统进行了详细的分析,确保其性能良好.实验和应用证明:该液压系统运转平稳,稳定性和调节性能较好且密封可靠,使用效果良好.

请允许我造个词:结构现象学,因为我认为这个词最能恰如其分地描述这座佚人营造为之奋斗了4年的大房子.结构+现象学,既是我对传统民居遗产的个人总结,也是我们一直以来执着的建筑品质,在之前曾用过"自由结构""白描建筑"这样的词语,但我觉得"结

Life-history theory predicts that in hibemators age of maturation is related positively to body size and negatively to the duration of active season aboveground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observations of marked individuals to determine the age of maturation in males through analysis of age-dependent variation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behavior during the mating season. Yearling males were smaller, lighter, had lower level of fecal testosterone, emerged later and had smaller home ranges than older males. Social activity and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters varied with age. Cluster analysis revealed two behavioral tactics: "active" males (adults only) emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heavier than "passive" males (both yearling and adult). Thus, males of S. fulvus reached adult size and matured after two hibernations, which is relatively fast for such a big species with short active period. Indirect evidence for copulations and high variation among yearlings in all parameters suggest that some of them might successfully compete with adults. Active tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passive tactic of residing is energy saving and good for adults in poor condition and for yearlings that are continuing to grow.

日本某公司从1960年开始潜心研究PA透明树脂,相继成功研发高透明、低吸水性、尺寸稳定性的TR55和TR90树脂并推向市场.

不同再生骨料取代率混凝土柱耐火性能试验简介作为一种新型环保材料,再生混凝土研究已成为学术界和工程界关注的热点和前沿问题之一.为研究不同强度、不同再生混凝土取代率的再生混凝土柱的耐火性能,进行了5个足尺混凝土柱在竖向荷载和温度场耦合作用下的耐火性能试验.其中2个试件为普通混

Models of optimal escape strategy predict that animals should move away when the costs of fleeing (metabolic and opportunity costs) are outweighed by the costs of remaining. These theoretical models predict that more vulnerable individuals should be more reactive, moving away when an approaching threat is further away. We tested whether escape behaviour (includ- ing 'escape calling') ofLithobates sphenocephalus approached by a human was influenced by body size or the initial microhabi- tat that the individual was found in. Irrespective of their size, frogs in the open tended to remain immobile, enhancing their cryp- sis. Frogs in cover showed different responses according to their body size, but, contrary to our initial predictions, larger frogs showed greater responsiveness (longer flight initiation distance and distances fled) than small frogs. Small frogs tended to remain closer to water and escaped into water, while larger individuals were more likely to jump to terrestrial cover and call during escape. Density of frogs near the focal animal had no effect on escape behaviour. This study indicates a range of escape responses in this species and points to the importance of divergent escape choices for organisms which live on the edge of different environments .

工业固体废弃物如粉煤灰、高炉矿渣、锅炉炉渣等作为水泥以及混凝土的矿物掺合料已得到广泛应用,废弃物集中使用在水泥的熟料烧制和熟料粉磨这两个环节.粉煤灰和矿粉是混凝土中最常用也是最主要的掺合料.掺合料的总量及其比例对混凝土性能非常重要,通过分析水泥中的掺合料才能准确把握混凝土的实际掺合料及其比例.

为分析混凝土构件高温后的力学性能和反应规律,开发了基于纤维单元算法的程序,接口大型通用有限元程序ABAQUS,并建立起混凝土结构受火后的数值模型.对两跨连续梁、板进行受火后反应分析,并将梁板加载点处荷载位移曲线及混凝土压应变与实验数据对比,验证了数值模型的合理性,表明纤维单元模型可以较好地模拟钢筋混凝土构件火后残余力学性能.分析结果为三维受火框架分析及数值模拟提供了参考.