Early age cracking of concrete has re - emerged as an important issue all over the world in recent years . the stress , due to restrained volume change related to thermal deformation and shrinkage in the early age concrete , is the main driving force for the deleterious cracking in the construction stage . during the development of the stress , creep , a very important property of concrete , is always developing . creep contributes to 40 ? - 50 ? reduction of the elastically induced stress in the restrained specimen . ring test , a qualitative test , can provide information to assess the potential for cracking of different concrete . an overview of ring test developed in recent years and mechanism of uniaxial tensile creep test is described in this paper at first . then , an innovative test equipment based on ring test is outlined 近年来混凝土早期裂缝问题再次引起全球工程界的广泛关注.早期混凝土由于体积变形受到约束而产生的应力是导致混凝土开裂的主要因素.在混凝土应力发展的同时,混凝土徐变也在同时发生着变化.有研究表明,徐变能减少40 ? - 50 ?的早期应力.圆环试验是用于定性评价混凝土材料抗裂性能的试验方法之一.本文首先分析了圆环试验和单轴拉伸徐变试验的原理,创造性地将圆环试验用于测量早期混凝土的干缩徐变,并设计了试验方案
Under the new trade system , interference of government to agricultural products " produce , consume and trade will be restricted , the structure of agricultural products trade will more and more depend on every country ' s competitive strategies about comparative advantage and competitive advantage of every agricultural product 在新的贸易制度下，国家对农产品生产、消费和贸易的政策干预将受到约束，农产品贸易格局将会愈来愈多地取决于各国在不同商品上具有的比较优势和所采取的竞争策略。
However , the research of logistics in our country is still lacking . there are some shortages in the logistics operation management , information modernization , production model and storage model , which leading to unbalance to the logistics of enterprise , inefficiency to the system , increase of opportunity cost , and harm to the development of company 例如在制造企业中，存在物流作业管理、监控不完善，信息现代化程度低，生产模型不合理，仓储分类、管理无序化等不足，这样在生产中形成了多处瓶颈，使企业内物流不平衡，系统效率的提高受到约束，产生巨大的机会成本，给企业带来诸多不良影响。
By using dta , ir and xrd analysis , the result show that : in the gel glass of these two system , the phase change of the zirconia and the alumina are restricted because of the high content of silica which leads to the stabilization of the prepared materials . and the applications of these two materials is introduced briefly . by using absorption spetrum and fluorescence spetra analysis , the result show that : in the gel glass of the nd - doped sio2 - al2o3 gel bulk glass - ceramic , the strongest emmision is at about 1 . 06u m , the clustering of nd3 + ion is controlled by the addition of alumina which creates the " cage effect " to nd3 + ion 同时分别对凝胶进行了dta 、 ir 、 xrd分析，结果表明：对于此两个系统的凝胶玻璃-陶瓷，由于二氧化硅含量较高，使得氧化锆及氧化铝的相变受到约束，从而保证所制备材料的稳定化，同时对两种材料的应用也作了简单介绍；对掺钕sio _ 2 - al _ 2o _ 3激光玻璃-陶瓷进行了荧光及吸收光谱分析，结果表明：钕铝共掺杂二氧化硅玻璃的最强发射处于1 . 06 m左右，加入的少量氧化铝使钕离子产生“笼效应” ，阻止钕的团聚。
Within his heart or at the level of his subconsciousness , smith had already formed his resolutions to the adam smith problem , these are that , in the one hand , he let moral restraint formed by spectators " sympathizing to limit people ' s motives from their self - interests within the extent of not injuring others , and thus gave altruistic actions much space of development , and harmonized the relation between economy and ethics , egoism and altruism of humanity through the process of valuing and sympathizing among people . on the other hand , he explained individual actions from self ? interest to produce automatically beneficial results for others in the systematic level by the market mechanism of invisible hand , thereby resolved the contradiction of self - interest and altruism 在斯密的内心里或潜意识层面上，他早已形成了对“亚当?斯密问题”的解决方案，这就是:一方面，他通过旁观者的同情过程所形成的道德约束，使个人的利己冲动受到约束，尽量保持在不伤害他人的范围内，并由此给予利他的行为以相当的发展空间，通过人们之间的相互情感作用与评价过程来协调经济与伦理、人性的利己与利他的关系;另一方面，他通过“看不见的手”这一市场机制，在体制的、制度的层面上说明了个人的利己行为自发地产生利他的道德结果，从而解决了自利与利他的矛盾。
