963 resultados para lab


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Sustainable water use is seriously compromised in the North China Plain (NCP) due to the huge water requirements of agriculture, the largest use of water resources. An integrated approach which combines the ecosystem model with emergy analysis is presented to determine the optimum quantity of irrigation for sustainable development in irrigated cropping systems. Since the traditional emergy method pays little attention to the dynamic interaction among components of the ecological system and dynamic emergy accounting is in its infancy, it is hard to evaluate the cropping system in hypothetical situations or in response to specific changes. In order to solve this problem, an ecosystem model (Vegetation Interface Processes (VIP) model) is introduced for emergy analysis to describe the production processes. Some raw data, collected by investigating or observing in conventional emergy analysis, may be calculated by the VIP model in the new approach. To demonstrate the advantage of this new approach, we use it to assess the wheat-maize rotation cropping system at different irrigation levels and derive the optimum quantity of irrigation according to the index of ecosystem sustainable development in NCP. The results show, the optimum quantity of irrigation in this region should be 240-330 mm per year in the wheat system and no irrigation in the maize system, because with this quantity of irrigation the rotation crop system reveals: best efficiency in energy transformation (transformity = 6.05E + 4 sej/J); highest sustainability (renewability = 25%); lowest environmental impact (environmental loading ratio = 3.5) and the greatest sustainability index (Emergy Sustainability Index = 0.47) compared with the system in other irrigation amounts. This study demonstrates that application of the new approach is broader than the conventional emergy analysis and the new approach is helpful in optimizing resources allocation, resource-savings and maintaining agricultural sustainability.

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As a high efficiency separation technique, capillary electrophoresis(CE) has been widely used in various fields of analytical science. Amperometry is one of the most sensitive electrochemical detection methods in CE. The capillary/electrode decoupling mechanism, applications,of new electrode systems in CE, detection cell technique are discussed in detail. Amperometric detection is compatible with microfabricated CE chips and will make the concept of lab-on-a-chip become a reality. Because of these progresses, amperometry is becoming a widely acceptable detection method,for more chemical and biological analytes.

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带电粒子与绝缘体表面相互作用的研究揭示了很多新的物理现象和物理规律,目前该研究领域已拓展到原子物理,固体物理,等离子体物理等领域,特别是促进了纳米材料,超小尺寸半导体芯片制作,固体结构分析等应用领域的发展。本论文介绍了低能高流强电子束与绝缘体相互作用实验平台的建设,包括强流LaB6电子枪,64通道一维位置灵敏法拉第筒,电流电压转换放大器,基于Lab VIEW的数据获取软件系统等。研究了低能高流强电子束与锥形绝缘毛细管之间的相互作用。测量了出射电子的角分布与能谱,研究了入射电子能量、流强对电子传输效率的影响,分析了电子与高电荷态粒子同毛细管相互作用的区别。用低能高流强电子束与等内径弯曲绝缘管相互作用,测量了出射电子的角分布,研究了入射能量与流强对导向效应的影响。研究表明,与高点和态离子相比,电子与绝缘管相互作用有许多新的特性,电子传输效率较高电荷态粒子小1-2个数量级,且能量损失严重。量子反射和多次小角度散射是电子导向的主要原因

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胸苷酸合成酶(thymidylate synthase,简称TS)和二氢叶酸还原酶(dihydrofolate reductase, 简称DHFR)都是叶酸依赖性酶,在维持DNA合成和DNA修复上发挥关键作用,并且多年来一直是肿瘤研究和化疗的重要靶点。我们前期的研究发现,TS和DHFR在翻译水平上存在负反馈调控机制。人TS和DHFR可以与其自身的mRNA结合,从而抑制mRNA的表达,化疗药物可以与TS或者DHFR相互作用,形成的复合物不能与TS mRNA结合, 使负反馈机制丧失。因此深入研究TS和DHFR的翻译调控机理,对阐明肿瘤抗药性机制,对发现新的抗肿瘤药物和肿瘤的治疗都具有十分重要的意义。 本论文利用mRNA体外展示技术,构建多肽库(约10万亿种多肽分子),利用多种实验手段将mRNA体外展示技术进行优化,提高了多肽库融合肽的产量,提高了mRNA体外展示技术筛选的特异性。将TS mRNA分子上的顺式因子TS30 RNA固定于磁珠上,将融合肽库与顺式因子作用,经过6轮循环,由多肽库中获得了与TS mRNA高度亲和的多肽序列,体外结合实验证明亲和肽可以与TS全长mRNA结合,体外翻译实验证明多肽可以抑制TS mRNA的翻译。并且利用phage display技术由噬菌体肽库(12个氨基酸随机肽库)经过四轮筛选,分别筛选到TS和DHFR的亲和肽,凝胶阻滞实验证明它们分别能与TS和DHFR mRNA结合。 本论文利用的展示技术可以广泛应用于特异靶点的蛋白质筛选,并且本论文筛选到的TS和DHFR亲和肽可以作为TS和DHFR的抑制剂,从而为获得新型的抗肿瘤药物奠定基础。

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分析超高压输电线路架空地线上的障碍物类型以及跨越这些障碍的过程。可以发现,巡检机器人采用双臂交替跨越障碍,越障过程简单。但是由于受巡检机器人自身重力偏矩的影响和手臂长度尺寸的限制,当单臂悬架在架空地线上时,导致巡检机器人本体倾斜,另一手臂完成脱线和上线任务变得十分困难,有时甚至造成越障失败。为了解决上述问题,提出质量调节的控制方法。该方法通过调节巡检机器人的质心,使巡检机器人的本体保持水平状态。为了验证质量调节控制方法的正确性,采用Lagrange方法建立巡检机器人动力学模型,通过仿真试验、实验室模拟实际架空地线试验以及超高压实际现场试验说明了提出方法的可行性。

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结合智能机器人多传感器实验平台的研制工作 ,系统介绍了其图像伺服子系统的工作原理、系统构成以及实现方案 ,涉及图像处理、机器视觉和机器人跟踪控制等相关内容 ,并讨论了物体自动识别和抓取过程中需要注意的一些问题 .

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本文结合智能机器人多传感器实验平台的研制工作,系统地介绍了图像传感器在线标定的原理和方法,并对标定系统的构成做了概述,同时结合实验对相关问题进行进一步的探讨。

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本文介绍了基于工业以太网的载人潜水器的信息综合显控系统。详细地描述了该系统的软件结构及各相关模块的特点,并对系统中各部分所实现的功能进行了详细的介绍。目前,该系统已在实验室进行了实验,实验效果良好。

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介绍了基于工业以太网的载人潜水器的数据采集与监控系统。简要地阐述了载人潜水器的重要性。详细地描述了该系统的硬件结构及各智能节点的特点,并对系统中各层所实现的功能进行了详细的介绍。目前,该系统已在实验室进行了实验,实验效果良好。

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本文介绍了我们研制开发的一种用于自主移动机器人的激光全局定位系统 ,重点描述了该系统的硬件结构和工作原理 ,介绍分析了定位算法 .文章最后介绍了该定位系统在实验室条件下所进行的实验 .实验结果表明 :该系统具有较高的定位精度和抗干扰能力 ,是自主移动机器人理想的定位工具 .

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具有自主的全局定位能力是自主式移动机器人传感器系统的一项重要功能 .为了实现这个目的 ,国内外均在不断地研究发展各种定位传感器系统 .这里介绍了一种采用光学原理的全方位位置传感器系统 .该传感器系统由主动式路标、视觉传感器、图象采集与数据处理系统组成 .其视觉传感器和数据处理系统可安装在移动机器人上 ,然后可通过观测路标和视角定位的方法 ,计算出机器人在世界坐标系中的位置和方向 .实验证明 ,该系统可以实现机器人的在线定位 ,其采样速率和精度能够满足实用要求 .

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在现代工业生产过程中,螺纹联接由于稳定可靠、拆卸方便,而广泛应用于众多的机构装配当中。目前在中国,由于传统工艺和技术水平的原因,广泛应用在装配线上的是气动与液压扳手,其存在操作不方便、工人劳动强度大、效率低、角度和扭矩控制精度差,无法实现集中式管理等缺点。这也逐渐成为制约我国装备制造业发展的重要瓶颈。随着近几年装备制造业的飞速发展,对螺纹装配的效率和质量提出了更高的要求,自动螺纹拧紧机由于其装配效率高、控制精确、能够实现网络化等优点,逐渐应用于发动机、制冷压缩机、变速箱、机床、仪表等对螺纹拧紧的角度和位置精度要求很高的场合。但目前,我国所使用的自动螺纹拧紧机还完全依赖于国外,国内在自动螺纹拧紧机的研制和设计上才刚刚起步,同国外相比还存在着较大的差距。 本论文适应装备制造业的发展和自动螺纹拧紧设备市场的需要,根据现代螺纹拧紧理论与技术的发展情况,对自动螺纹拧紧机进行了深入研究。本论文结合嵌入式技术,设计出了基于嵌入式微控制器的螺纹拧紧机机轴控制器。 论文的第一部分介绍了自动螺纹拧紧机国内外发展现状,在此基础上,提出了本课题的研究目标与研究内容。 第二部分详细分析了现代螺纹拧紧理论。在此基础上,给出了在机轴控制器上实现精确预紧力控制的控制算法、包括紧固扭矩的计算、转角的计算、屈服点的计算等问题。同时,在扭矩控制中采用角度监视;在转角控制中采用扭矩监视;在屈服极限控制中采用扭矩监视和角度监视。可以自动对最终拧紧结果的有效性进行判断,从而实现有效、准确的螺纹多目标控制方式。本论文实现了扭矩控制/角度监视、转角控制/扭矩监视、屈服极限控制/扭矩、角度监视。 第三部分介绍了机轴控制器的硬件结构。本文采用美国Silicon Lab公司的C8051F040微控制器,使得成本大大降低。在硬件设计中采用大量可靠性设计,保证了螺纹拧紧机在复杂的工业环境下能够稳定工作。 第四部分介绍了机轴控制器的软件设计。在机轴控制软件的实现中,引入了嵌入式实时操作系统 C/OS-II。这部分首先将 C/OS-II移植到单片机C8051F040上,接着在 C/OS-II上完成整个机轴控制软件的编写。 C/OS-II的使用使得上层应用程序容易设计和扩展,提高了机轴控制软件的实时性。 实验证明,本文设计的基于嵌入式微控制器的螺纹拧紧机机轴控制器,控制精度较高、性能稳定、质量可靠、操作简便。在扭矩控制模式下,误差可以控制在5%以内;在屈服极限控制模式下,误差可以控制在15%以内。同时,由于在控制软件的设计中引入了嵌入式实时操作系统 C/OS-II, 使得该控制系统具有较好的扩展性和实时性。本设计进一步缩小了我国与国外同类产品的差距,因此,具有很好的市场发展前景。

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So far, there is no methods of logging interpretation effective enough to identify a low resistivity payzone since its resistivity value almost equals to that of an aquifer although many low-resistivity payzones have been found in lots of petroliferous basins worldwide. After a thorough study on those technical difficulties of the logging interpretation for the low-resistivity payzones, some corresponding resolutions have been put forward in this paper. In order to reveal its microscopic mechanism, researches on the discovered low-resistivity payzones have been carried on with analyses of core and lab test data, thus main influencing factors of the low-resistivity reservoirs have been pointed out including conductivity minerals, clay minerals, fluids, porosity and pore structure. In order to make clear the degree of influence of those reservoir factors on resistivity logging(log), lab studies and numeral simulations have been done with the typical core and formation water samples, therefore, their influence degrees have ascertained quantitatively or semi-quantitatively. The distribution law and possible distribution areas of the low-resistivity payzones in Jiyang Depression have been figured out firstly after the macroscopic geology origins (sedimentation, dynamic accumulation process, diagenesis etc.) in the area have been studied. In order to resolve the problem of difficult logging-interpretation, methods of interpretation and identification have been brought forward creatively according to the low-resistivity payzone type ascribed to macroscopic geology laws and to the combined features of logging traces, after a systemic summary of different responses of logging caused by different microscopic mechanism. Those methods have been applied in Dongying and Huimin Sag of Shengli Exploration Area, precision of identification of the low-resistivity payzones improved effectively and good economic attraction prove their great prospect.

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China locates between the circum-Pacific and the Mediterranean-Himalayan seismic belt. The seismic activities in our country are very frequent and so are the collapses and slides of slope triggered by earthquakes. Many collapses and slides of slope take place mainly in the west of China with many earthquakes and mountains, especially in Sichuan and Yunnan Provinces. When a strong earthquake happening, the damage especially in mountains area caused by geological hazards it triggered such as rock collapses, landslides and debris flows is heavier than that it caused directly. A conclusion which the number of lives lost caused by geological hazards triggered by a strong earthquake in mountains area often accounts for a half even more of the total one induced by the strong earthquake can be made by consulting the statistical loss of several representative earthquakes. As a result, geological hazards such as collapses and slides of slope triggered by strong earthquakes attract wide attention for their great costs. Based on field geological investigation, engineering geological exploration and material data analysis, chief conclusions have been drawn after systematic research on formation mechanism, key inducing factors, dynamic characteristics of geological hazards such as collapses and slides of slope triggered by strong earthquakes by means of engineering geomechanics comprehensive analysis, finite difference numerical simulation test, in-lab dynamic triaxial shear test of rock, discrete element numerical simulation. Based on research on a great number of collapses and landslides triggered by Wenchuan and Xiaonanhai Earthquake, two-set methods, i.e. the method for original topography recovering based on factors such as lithology and elevation comparing and the method for reconstructing collapsing and sliding process of slope based on characteristics of seism tectonic zone, structural fissure, diameter spatial distribution of slope debris mass, propagation direction and mechanical property of seismic wave, have been gotten. What is more, types, formation mechanism and dynamic characteristics of collapses and slides of slope induced by strong earthquakes are discussed comprehensively. Firstly, collapsed and slided accumulative mass is in a state of heavily even more broken. Secondly, dynamic process of slope collapsing and sliding consists of almost four stages, i.e. broken, thrown, crushed and river blocked. Thirdly, classified according to failure forms, there are usually four types which are made up of collapsing, land sliding, land sliding-debris flowing and vibrating liquefaction. Finally, as for key inducing factors in slope collapsing and sliding, they often include characteristics of seism tectonic belts, structure and construction of rock mass, terrain and physiognomy, weathering degree of rock mass and mechanical functions of seismic waves. Based on microscopic study on initial fracturing of slope caused by seismic effect, combined with two change trends which include ratio of vertical vs. horizontal peak ground acceleration corresponding to epicentral distance and enlarging effect of peak ground acceleration along slope, key inducing factor of initial slope fracturing in various area with different epicentral distance is obtained. In near-field area, i.e. epicentral distance being less than 30 km, tensile strength of rock mass is a key intrinsic factor inducing initial fracturing of slope undergoing seismic effect whereas shear strength of rock mass is the one when epicentral distance is more than 30 km. In the latter circumstance, research by means of finite difference numerical simulation test and in-lab dynamic triaxial shear test of rock shows that initial fracture begins always in the place of slope shoulder. The fact that fracture strain and shear strength which are proportional to buried depth of rock mass in the place of slope shoulder are less than other place and peak ground acceleration is enlarged in the place causes prior failure at slope shoulder. Key extrinsic factors inducing dynamic fracture of slope at different distances to epicenter have been obtained through discrete element numerical simulation on the total process of collapsing and sliding of slope triggered by Wenchuan Earthquake. Research shows that combined action of P and S seismic waves is the key factor inducing collapsing and sliding of slope at a distance less than 64 km to initial epicenter along earthquake-triggering structure. What is more, vertical tensile action of P seismic wave plays a leading role near epicenter, whereas vertical shear action of S seismic wave plays a leading role gradually with epicentral distance increasing in this range. On the other hand, single action of P seismic wave becomes the key factor inducing collapsing and sliding of slope at a distance between 64 km and 216 km to initial epicenter. Horizontal tensile action of P seismic wave becomes the key factor gradually from combined action between vertical and horizontal tensile action of P seismic wave with epicentral distance increasing in this distance range. In addition, initial failure triggered by strong earthquakes begins almost in the place of slope shoulder. However, initial failure beginning from toe of slope relates probably with gradient and rock occurrence. Finally, starting time of initial failure in slope increases usually with epicentral distance. It is perhaps that the starting time increasing is a result of attenuating of seismic wave from epicenter along earthquake-triggering structure. It is of great theoretical and practical significance for us to construct towns and infrastructure in fragile geological environment along seism tectonic belts and conduct risk management on earthquake-triggered geological hazards by referring to above conclusions.

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Movements of separation and convergence between the continental plates, as well as the interaction beween the lithosphere and asthenosphere is the dominant factor in plate evolution. Moreover, those phenomena, the formation, enrichment and storage of energy and mineral strorage, as well as intraplate earthquakes are all relate to plate movement and evolution. Therefore, the study of continental lithosphere, is not only helpful to analysing the dynamic model between lithosphere and asthenoshere as well as different plates, but also important to the nation's economy and the people's livelihood. And the lithospheric thickness or Lithosphere-Asthenosphere Boundary (LAB) is one of the most important parameters in study of continental lithospheric formation and evolution. Chinese continent composed by many small plates, possesses diverse type of lithospheric structure. But our knowledge ahout Chinese continental lithosphere, especially the regional research, is almost based on the low-resolution results of surface wave dispersion analysis and seismic wave tomography. Howere, recently a technique employing S-to-P converted body waves (the S receiver function technique) has been developed that can be used to identify the LAB with a higher resolution. This thesis has collected waveform data of 232 broadband seismic stations that are located in China and neighboring regions. Using teleseismic S-wave and P-wave receiver functions have studied the Chinese continental lithospheric structure. The results of this study indicate that, the thickness of Chinese continental lithosphere become thinner from west to east, and obvious difference exists between different blocks. Four types of lithosphere have been detected: (1) Convergence thicking lithosphere in Tibetan Plateau; (2) Stable lithosphere in Tarim basin and upper Yangtze craton; (4) Active lithosphere in Orogenic belts; (4) Break-up thinning lithosphere in east China craton