245 resultados para SPAN
Resumo:
In order to realize fast development of the national economy in a healthy way and coordinate progress with whole society, the country has implemented the strategy of development of the western region. An important action of finishing this strategic task is to accelerate the highway construction in the western region, join the western region and places along the coast, the river, the border with goods and materials, technology, and personnel interchanges, and then drive development of the local economy.The western region was influenced by the Himalaya Tectonization in Cenozoic, and the crust rose and became the plateau. In the course of rising, rivers cut down sharply to form a lot of high mountains and gorges.Because of topography and geomorphology, bridges in the traffic construction in the alpine gorge area are needed. Rivers have characteristics of large flow, fast velocity and high and steep river valley, so building a pier in the river is not only very difficult, but also making the cost increase. At the same time, the impact that the pier is corroded and the bridge base that is drawn to be empty by flow are apt to cause destruction of the pier. For those reasons, suspending bridge and cable-stay bridge are usually adopted with the single and large span. For the large span bridge, the pier foundation could receive ten thousand and more vertical strength, bending moment and near kiloton horizontal thrust.Because bank slope in the alpine gorge district is cut deeply and unsettled big, natural stability is worse under endogenic and exogenic force. When bank slope bears heavy vertical strength, bending moment and horizontal thrust facing the river, it will inevitably make the balance state of rock and soil mass change, bridge bank slope deform, and even destroyed. So the key problem at the time of the large span's bridge construction in the alpine gorge area is how to make it stable.So based on the spot investigation, the Engineering Geology Analysis Method is very important to grasp the bank slope stability. It can provide the bank slope stability macroscopic ally and qualitatively, and reference to the indoor calculation. The Engineering Geology Analysis Method is that by way of analyzing and investigating terms of bank slope instability, stability development trend, the ancient rock slide and devolution in the site, stability comprehensive evaluation primarily, current and future stability of bank slope is gotten, realizing the intention to serving the concrete engineering.After the Engineering Geology Analysis Method is applied to project instances of BeiPan River Bridge and BaLin River Bridge, results are accord with bank slope actual conditions, which proves sites are suited to building bridges from site stability.we often meet bank slope stability issues in the traffic construction in the alpine gorge areao Before the evaluation of the bank slope stability, the engineering geological condition is investigated first. After that, the next exploration target and geology measures are decided. So, the Engineering Geology Analysis Method that the investigation of the engineering geological condition is the main content is quite important in practice. The other evaluations of the bank slope stability are based on it. Because foundation receives very heavy load, for the big span's bridge in the alpine gorge area, a long pile of the large diameter (D^0.8m) is usually selected. In order to reflect rock mass's deformation properties under rock-socketed pile function, the author has used the FLAG30 software for rock and soil mass and done many numerical simulations. By them, the author launches the further investigation on deformation properties of bank slope under different slope angle, pile length, diameter, elastic modulus, load, bank slope's structure, etc. Some conclusion meaningful to the design and produce are obtained.
Resumo:
<span>本文对粤北红岭、石人嶂、梅子窝、锯板坑等四个石英脉型钨矿的矿石样品进行了详细的矿相学和电子探针分析,在红岭钨矿中观察到黑钨矿与白钨矿共生或交代现象,并发现铌锰矿、(含)钨铌锰矿晶体。在石人嶂、梅子窝、锯板坑钨矿中发现较多黝锡矿,分布在黄铜矿、闪锌矿边缘,或呈乳滴状分布在黄铜矿中,部分黝锡矿中包裹锡石。红岭、石人嶂、梅子窝钨矿床中有不同程度的银矿化,根据(含)银矿物的能谱成分分析,区分出富硫铋铅矿、块辉铋铅银矿(第1、2、3亚种)、硫银铋矿、淡红银矿、脆银矿、硫铜银矿,并有含银4.78%~13.25%的硫铅铋盐、含银2.9%~12.19%的硫铜银盐、含银71.01%~90.74%的硫砷银盐及含银9.3%的硫氯铅铜盐等多种未定名矿物。红岭钨矿中含银矿物多以不规则粒状分散在铁闪锌矿、硅酸盐矿物中,含银矿物与主硫化物同时形成;石人嶂钨矿床中含银矿物主要为含银硫铜盐、硫铜银盐,在黄铜矿边缘形成含银矿物-闪锌矿的交代反应边,局部有含银硫铅铋盐、硫铋银盐;梅子窝钨矿床中主要为独立银矿物和少量自然银,多分布在方铅矿中或充填在硫化物裂隙中,含银硫铅铋盐、硫铋盐、硫砷铅银矿物较少。石人嶂、梅子窝钨矿床中银矿物种类丰富且含量较高,具有综合利用前景,两矿床部分样品中发育细脉型或边缘交代型的(含)银矿物,表明晚期热液叠加银矿化作用较强。四个矿床中的铋矿物主要为辉铋矿和自然铋,部分矿床中多含银铅铋硫盐类,在红岭钨矿中发现与辉铋矿共生的楚碲铋矿,石人嶂钨矿中有细脉状未定名铋铜硫盐。四个矿床的闪锌矿成分不同,石人嶂、梅子窝钨矿的含较高Cd,红岭、锯板坑钨矿的基本不含Cd,红岭钨矿闪锌矿中Fe含量变化较大.span>
Resumo:
The relationship between working memory (WM) and attention has attracted many researchers. In his embedded-processes model of WM, Cowan (1999, 2001) uses the term focus of attention to refer to the core component of WM, and proposes that the focus of attention of WM and that of perception have the same span, which is a fixed number. This hypothesis about the scope of attention has seldom been tested, although considerable studies have revealed that WM and attention have overlapping mechanisms. The present dissertation tests this hypothesis by examining the dual-task interference between Corsi Blocks Task (CBT) and Mutilple Object Tracking (MOT) and the findings demenstrate that Cowan’s hypothesis is not exactly true. The results of our first study show that the interference effect of MOT on CBT is a reliable indicator of whether and to which extent the attentional resoureces of WM and perception overlap. In the second study we find that the capacity of the common resources is not a fixed number but varies with the difficulty of control of attention. And the third study indicates that attentional resources used in WM and perception are partly independent, the overlapping part can attend to only one or two items or locations at a time. These findings can contribute to future studies on the capacity limitation of different cognitive functions, and to the development of relevant ability tests.
Resumo:
The present study explored the influence of working memory span on accentuation effects in discourse comprehension from the approach of individual difference. High and low working memory span subjects were selected by Reading Span Test. Sentence-by-sentence Auditory Moving Window paradigm was employed to measure the effects of accentuation on discourse comprehension. The on-line processing time of discourse comprehension was compared between consistent accentuation condition, inconsistent accentuation condition and controlled condition. The results indicated that the accentuation effects were influenced by working memory capacity. For low working memory subjects, consistent accentuation speeded up the on-line processing of spoken discourse, inconsistent accentuation slowed down the on-line processing of spoken discourse. But for high working memory span subjects, neither effect was manifested. The only significant difference was found between the condition of inconsistent accentuation and consistent accentuation. During spoken discourse comprehension, there was no significant difference in the on-line processing time between high and low working memory span subjects in consistent accentuation condition as well as in neutral accentuation condition. However, in the condition of inconsistence accentuation, low span subjects spent significantly more time on the on-line processing of spoken discourse than high span subjects. The results could be explained by the controlled attention view of working memory.
Resumo:
The relation between Attention and Age is an important problem about theory and practice. This approach investigated the problem experimentally. There were sixty subjects in this test, they were divided into three groups of gage. The range of this investigation connected with Attentional span, Attentional selection, Attentional undulation, Attentional shifting, and also with the function of brain corpus callosum for transferring and processing information. The conclusion has been drawn as follows: 1. The development of Attention is a continuous process, and has decrement related with increasing age. Such trendency of the Age-decrement has existed in fact sincethe adulthood. 2. The Age-decrement of Attention is caused by the decline of brain function, especially by the decline of speed of transferring information in neuvous system. 3. Attention level may be animportant index to measure the status of Age-decrement in the psychological function.