933 resultados para Railroad tracks Maintenance and repair


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On-site tracking in open construction sites is often difficult because of the large amounts of items that are present and need to be tracked. Additionally, the amounts of occlusions/obstructions present create a highly complex tracking environment. Existing tracking methods are based mainly on Radio Frequency technologies, including Global Positioning Systems (GPS), Radio Frequency Identification (RFID), Bluetooth and Wireless Fidelity (Wi-Fi, Ultra-Wideband, etc). These methods require considerable amounts of pre-processing time since they need to manually deploy tags and keep record of the items they are placed on. In construction sites with numerous entities, tags installation, maintenance and decommissioning become an issue since it increases the cost and time needed to implement these tracking methods. This paper presents a novel method for open site tracking with construction cameras based on machine vision. According to this method, video feed is collected from on site video cameras, and the user selects the entity he wishes to track. The entity is tracked in each video using 2D vision tracking. Epipolar geometry is then used to calculate the depth of the marked area to provide the 3D location of the entity. This method addresses the limitations of radio frequency methods by being unobtrusive and using inexpensive, and easy to deploy equipment. The method has been implemented in a C++ prototype and preliminary results indicate its effectiveness

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Tracking methods have the potential to retrieve the spatial location of project related entities such as personnel and equipment at construction sites, which can facilitate several construction management tasks. Existing tracking methods are mainly based on Radio Frequency (RF) technologies and thus require manual deployment of tags. On construction sites with numerous entities, tags installation, maintenance and decommissioning become an issue since it increases the cost and time needed to implement these tracking methods. To address these limitations, this paper proposes an alternate 3D tracking method based on vision. It operates by tracking the designated object in 2D video frames and correlating the tracking results from multiple pre-calibrated views using epipolar geometry. The methodology presented in this paper has been implemented and tested on videos taken in controlled experimental conditions. Results are compared with the actual 3D positions to validate its performance.

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Thymidylate synthase (TS), an essential enzyme in DNA synthesis and repair, plays a key role in the events of cell cycle regulation and tumor formation. Here, an investigation was presented about subcellular location and biological function of viral TS from lymphocystis disease virus from China (LCDV-C) in fish cells. Fluorescence microscopy revealed that LCDV-C TS was predominantly localized in the cytoplasm in fish cells. Cell cycle analysis demonstrated that LCDV-C TS promoted cell cycle progression into S and G2/M phase in the constitutive expressed cells. As a result, the cells have a faster growth rate compared with the control cells as revealed by cell growth curves. For foci assay, the TS-expressed cells gave rise to foci 4-5 weeks after incubation. Microscopic examination of the TS-induced foci revealed multilayered growth and crisscross morphology characteristic of transformed cells. Moreover, LCDV-C TS predisposed the transfected cells to acquire an anchorage-independent phenotype and could grow in 0.3% soft agar. So the data reveal LCDV-C TS is sufficient to induce a transformed phenotype in fish cells in vitro and exhibits its potential ability in cell transformation. To our knowledge, it is the first report on viral TS sequences associated with transforming activity. (C) 2007 Elsevier Inc. All rights reserved.

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本论文的实验内容立足于我所重离子治癌研究的基础之上,本着进行基础研究的目的,研究了肿瘤细胞对于重离子的辐射敏感性和重离子引起肿瘤细胞DNA双链断裂(DSB)及修复的情况,这可为我所开展重离子治癌提供有效的基础数据和理论参考,对于治疗计划的制定也具有重要的意义。实验从四个方面开展,首先考察了不同肿瘤细胞对低LETγ射线的辐射敏感性差异及其与修复可能存在的联系,其次考察了重离子在放射治疗中的优势及重离子用于肿瘤放射治疗的优越性,第三为了进一步寻求重离子对肿瘤细胞强杀伤能力的原因所在,对重离子引起的肿瘤细胞DSB及修复水平进行了研究,最后通过分次照射实验,考察细胞存活与细胞DSB修复水平之间可能存在的相关性。实验取得了一系列有意义的结果和结论: 1. 低LET电离辐射作用后,不同组织来源的肿瘤细胞的辐射敏感性有较大差 异,其各自的修复功能也有相应的差异,且肿瘤细胞的辐射敏感性与其修复能力呈负相关。 2.重离子具有的独特物理特性及其高LET下对肿瘤细胞的强杀伤作用,使得重离子成为肿瘤治疗的热点。与此同时,重离子还显示出其它值得关注的优势,它可以同样有效的杀伤不同肿瘤细胞,减弱了细胞间的敏感性差异,这对于治疗计划的制定和治疗对常规辐射抗性较高的肿瘤来说,具有重大的意义。对于临床的分次照射,重离子治疗时,细胞的亚致死修复明显降低,可以采取较少的照射次数就达到杀伤肿瘤的目的,这样大大提高了肿瘤治疗效率,同时减轻了病人的痛苦。 3.在两种高LET重离子引起细胞DSB及其修复实验中,初始DSB量均与剂量呈线性关系。 DSB的片段分布检测结果显示两种重离子辐照后DSB的分布呈明显的非随机分布,剂量增大时,大片段的DSB和小片段的DSB变化趋势不同:剂量超过一定数值后,小片段的DSB随剂量增大而呈现出高的增加速度,而大片段的DSB则呈现微弱增加甚至减少。同时LET变化对于这一现象存在影响。除了离子种类和LET之外,剂量也影响了DSB分布形式。修复实验结果显示4h后,残余的DSB相差不大。由于氩离子引起的初始DSB高于碳离子,在相同时间内,高LET的氩离子完成了对DSB更多的修复,这似乎提示,LET升高引起了更强的修复,但是这里值得考虑的有两点,一是慢修复的DSB所占的比例,二是错修复的问题,即使高LET的氩离子照射后DSB得到了更多的修复,但是其修复的忠实性并未得到证明,更多的工作还需要进行。 4.分次照射实验发现高LET的碳离子辐照后的剂量存活曲线不再存在明显肩区,分次照射细胞的存活也没有明显上升,这与光子辐照情况不同,应证了随着LET升高,分次效应降低的结论。同时检测DSB的引入情况,发现分次照射和单次照射时,DSB的引入并未发生明显变化,这显示在分次照射的间隙中,重离子引入的DSB并未得到明显的修复。提示细胞对高LET照射更为敏感与其对高LET辐照引起的DSB修复能力降低之间的相关性

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Red tides (high biomass phytoplankton blooms) have frequently occurred in Hong Kong waters, but most red tides occurred in waters which are not very eutrophic. For example, Port Shelter, a semi-enclosed bay in the northeast of Hong Kong, is one of hot spots for red tides. Concentrations of ambient inorganic nutrients (e.g. N, P), are not high enough to form the high biomass of chlorophyll a (chl a) in a red tide when chl a is converted to its particulate organic nutrient (N) (which should equal the inorganic nutrient, N). When a red tide of the dinoflagellate Scrippsiella trochoidea occurred in the bay, we found that the red tide patch along the shore had a high cell density of 15,000 cells ml(-1), and high chl a (56 mu g l(-1)), and pH reached 8.6 at the surface (8.2 at the bottom), indicating active photosynthesis in situ. Ambient inorganic nutrients (NO3, PO4, SiO4, and NH4) were all low in the waters and deep waters surrounding the red tide patch, suggesting that the nutrients were not high enough to support the high chl a >50 mu g l(-1) in the red tide. Nutrient addition experiments showed that the addition of all of the inorganic nutrients to a non-red-tide water sample containing low concentrations of Scrippsiella trochoidea did not produce cell density of Scrippsiella trochoidea as high as in the red tide patch, suggesting that nutrients were not an initializing factor for this red tide. During the incubation of the red tide water sample without any nutrient addition, the phytoplankton biomass decreased gradually over 9 days. However, with a N addition, the phytoplankton biomass increased steadily until day 7, which suggested that nitrogen addition was able to sustain the high biomass of the red tide for a week with and without nutrients. In contrast, the red tide in the bay disappeared on the sampling day when the wind direction changed. These results indicated that initiation, maintenance and disappearance of the dinoflagellate Scrippsiella trochoidea red tide in the bay were not directly driven by changes in nutrients. Therefore, how nutrients are linked to the formation of red tides in coastal waters need to be further examined, particularly in relation to dissolved organic nutrients. (C) 2008 Elsevier B.V. All rights reserved.

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针对传统的分层式体系结构在UUV 控制系统开发设计、维护和升级过程中所遇到的困难,首先分析了集中式控制和管理方法的不足和原因。在此基础上,借鉴自主计算的思想,提出了分散控制和管理的体系结构。这种方法把系统中每个独立的功能模块都抽象成为具有相同模型的控制基元,称之为“自主基元”,然后通过自主基元层次式、嵌套式的组织,构成完整的系统。分析表明,这种方法能够缩短控制系统的开发周期,也降低了维护和升级的难度。

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The ionogram acquired with the ionospheric vertical sounding method is the oldest data in the history of ionospheric research. Using of modern microelectronics and computer technology to digitalize, analyse and preserve the huge amount of historical film ionogram has become more and more important and urgent. This paper introduced the progress of the film ionogram digitalization by using digital image processing technologies to correct and repair film ionogram and convert them in an exchangeable format. An analysis and conversion software, basing on this method, has been developed for the film ionogram analysis, and then it introduces the application of this software by combining the SAO Explorer program for Wuhan film ionogram and pseudo-color ionogram in Yamagawa in Japan. It shows that our method is reliable,and the developed software is used friendly and provides a positive solution in digitalization and analysis of huge amount of historical film ionogram. Firstly, we briefly introduce the film ionogram and the process of its digitalization. By observing a amount of film ionogram, we obtain some common characteristics of the digitalized film ionogram following as: (1) the image rotation are caused by scanning; (2) the vertical axis of a large number of film ionogram exist more or less tilt and bending ; (3) coordinates of the film ionogram appear the non-uniformity phenomena result from the instability of driving motor rotation and the error of altitudinal cursor orientation. Moreover, based on the characteristics of the film ionogram and the SAO Explorer software which is widely used for the digital ionogram analysis in the world, a new method has been developed for film ionogram procession. The method contains the image geometric correction and film ionogram format conversion. The image geometric correction includes such as image rotation correction, vertical correction and coordinates scale correction. After geometric correction, the BMP file format images will be converted to the SBF file format images. Then, we also discuss the data format converting methods, which include two methods of the image data mapping basing on the normalization and logarithm, and the method of the preprocessing of the noise filtering and the threshold setting. Combining with SAO Explorer software, we successfully obtain ionospheric parameters and electron profile from the converted SBF file format digital ionograms. Based on the above method, we developed the software for the film ionogram to realize its correction analysis and conversion of the image format, and then give a introduction for its function and operation. Subsequently, the software are applied into the Wuhan film ionogram which separately observed in the high solar activity year and the low in 1980s last century. The results reveal the converted SBF digital ionogram almost preserve the all echo information of the film ionogram. Furthermore, we expressly discuss the application to the Wuhan film ionogram in 1958 in order to validate the applicability and credibility of the software. And it is showed that the important information of the film ionogram are maintained into the SBF digital ionogram. It is represented that there is credibility for conversion of the software when it applied in the older film ionogram. In sum, this software could apply to the digitalization and analysis of huge amount of historical film ionogram. Last, we extended the function of the software by bring some new conversion method and used it to apply to the pseudo-color ionogram of yamagawa in Japan. The results show that the converted ionogram information basically maintain the importantly ionogram information and the error of scaling of converted SBF file format image is almost acceptable, though there is no preprocessing for the original ionogram. Hence, we could extend the applicable range of the software and apply it to all kinds of simulative ionogram imaging by improving the method and software.

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China is experiencing a rapid development of highway ever since 1990s. By the end of 2004, the total length of the highway summed up to 33 thousand kilometers, ranking 2n in the world. After the open of highway, the accumulation of time and traffic causes the decrease of its capability. To ensure its good quality, security and operation functions, we should take some reasonable measures to maintain it periodically. At present, a big problem is that the traditional maintain measures can no longer meet the increasing requirements. Due to the characters of highway, the relationship of various maintenance data and geographic positions is even closer than any others. If we wan to improve the quality and efficiency of the maintenance work, particularly when there is need for decision-making, a great number of data that is related to geographic positions are absolutely necessary. Evidently, Geographical Information System (GIS) has incomparably advantages in dealing with these spatial information. As a result, a management system for highway maintenance work based on GIS became inevitable for the development of the maintenance of highway. The purpose of this paper is to establish a management system for highway maintenance work base on Geographical Information System (GIS), Global Positioning System (GPS) and spatial database, to manage all kinds of problems encountered in the work, and to provide support on information and methods. My study mainly includes: (1) Analysis on the current status of the maintenance and management work; overview on the history of domestic and international highway maintenance management systems; identifying the necessity and importance for establishing a management system for highway maintenance work based on GIS. (2) Based on the requirement analysis, I proposed a general design for this management system, and discussed the objective, design principles, framework, systematical structure and function design. (3) Outdoor data collection is not only a prime way to understand the current situation of the road, but also an important method for data update after the system is put into use. This paper also intends to establish a set of plan to collect data efficiently and precisely which is based on GIS and GPS technologies. (4) The maintenance management database is a supporting platform for various maintenance decision-makings. Such decisions need the support of a great amount of data, which would cause other problems, such as the diversity of the data source, difference of data formats. This paper also discussed how to deal with these problems and establish such a database. (5) To propose an approach to assess the condition of pavement, based on GIS and related maintenance models. Among all the maintenance models, the two for assessing and forecasting pavement condition are the most important and mature. This paper also analyzed these two models and introduced them in terms of the integration of models. (6) This paper took the Guangshen Highway for example, explaining how to realize a GIS for management of highway maintenance work.

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Organizations are increasingly turning to team-based structures to contend with the pressure of the increasing global competition, consolidation, innovation and need for diverse skills, expertise, and experiences. This ongoing transformation in the basic organization of work has captured the attention of researcher. And group and team research has become increasingly centered in the fields of organizational psychology and organizational behavior since the 1990s. A great deal empirical studies were conducted; a number of variables contributing to team effectiveness and several IPO models were summarized. But teamwork behaviors, the dynamic and adaptive interactions among team members during the task completion, were still very vague. So were the team task characteristics, an important input variable of the IPO models. The effects of team task characteristics and teamwork behaviors on team effectiveness were explored according to IPO model on the basis of the reviews on previous studies, the Hierarchical Conceptual Structure of Teamwork Behaviors (Rousseau et al.,2006), and the task characteristic theory(Hackman & Oldman, 1975). The questionnaire data from 479 team members and 110 team managers of 22 organizations were analyzed. The results indicate: A. Teamwork behaviors consist of 13 behavioral dimensions: team mission analysis, goal specification, planning, coordination, cooperation, information exchange, performance monitoring, backing-up behaviors, intra-team coaching, collaborative problem solving, team practice innovation, psychological support and integrative conflict management. The hierarchical conceptual structure was partly supported with five variable identified, i.e., preparation of work accomplishment, task-related collaborative behaviors, work assessment behaviors, team adjustment behaviors and the management of team maintenance. The formal four variables are in a sequential way. B. The task characteristic theory at individual level is applicable to the team level. This means that the team task characteristics consist of task variety, identity, significance, feedback, autonomy, interdependence. C. The correlations among task characteristics, teamwork behaviors and outcomes support the IPO model. The regulation of team performance mediated the effects of task meaningfulness and interdependence on team outcomes, with the direct effects of task meaningfulness on the preparation behaviors and the direct effects of interdependence on the task-related collaborative behaviors. The management of team maintenance mediated the effects of autonomy on team cohesion and satisfaction. The regulation of team performance has a direct effect on the team performance and the management of team maintenance. And the management of team maintenance has a direct effect on the team attitude and the regulation of team performance.

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BitBox! is an installation that takes game music from the screen and brings it into the room. Using ultrasonic sensors, the system tracks your position in 3D space and uses your location in real time to create evolving soundscapes, dynamic textures and interactive music tracks. Shake and move to create your own music effect.

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P.M. Hastie and W. Haresign (2006). A role for LH in the regulation of expression of mRNAs encoding components of the insulin-like growth factor (IGF) system in the ovine corpus luteum. Animal Reproduction Science, 96(1-2), 196-209. Sponsorship: DEFRA RAE2008

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The folate pathway plays a crucial role in the regeneration and repair of the adult CNS after injury. Here, we have shown in rodents that such repair occurs at least in part through DNA methylation. In animals with combined spinal cord and sciatic nerve injury, folate-mediated CNS axon regeneration was found to depend on injury-related induction of the high-affinity folate receptor 1 (Folr1). The activity of folate was dependent on its activation by the enzyme dihydrofolate reductase (Dhfr) and a functional methylation cycle. The effect of folate on the regeneration of afferent spinal neurons was biphasic and dose dependent and correlated closely over its dose range with global and gene-specific DNA methylation and with expression of both the folate receptor Folr1 and the de novo DNA methyltransferases. These data implicate an epigenetic mechanism in CNS repair. Folic acid and possibly other nontoxic dietary methyl donors may therefore be useful in clinical interventions to promote brain and spinal cord healing. If indeed the benefit of folate is mediated by epigenetic mechanisms that promote endogenous axonal regeneration, this provides possible avenues for new pharmacologic approaches to treating CNS injuries.

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The meniscus plays a critical biomechanical role in the knee, providing load support, joint stability, and congruity. Importantly, growing evidence indicates that the mechanobiologic response of meniscal cells plays a critical role in the physiologic, pathologic, and repair responses of the meniscus. Here we review experimental and theoretical studies that have begun to directly measure the biomechanical effects of joint loading on the meniscus under physiologic and pathologic conditions, showing that the menisci are exposed to high contact stresses, resulting in a complex and nonuniform stress-strain environment within the tissue. By combining microscale measurements of the mechanical properties of meniscal cells and their pericellular and extracellular matrix regions, theoretical and experimental models indicate that the cells in the meniscus are exposed to a complex and inhomogeneous environment of stress, strain, fluid pressure, fluid flow, and a variety of physicochemical factors. Studies across a range of culture systems from isolated cells to tissues have revealed that the biological response of meniscal cells is directly influenced by physical factors, such as tension, compression, and hydrostatic pressure. In addition, these studies have provided new insights into the mechanotransduction mechanisms by which physical signals are converted into metabolic or pro/anti-inflammatory responses. Taken together, these in vivo and in vitro studies show that mechanical factors play an important role in the health, degeneration, and regeneration of the meniscus. A more thorough understanding of the mechanobiologic responses of the meniscus will hopefully lead to therapeutic approaches to prevent degeneration and enhance repair of the meniscus.

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Most studies on the environmental performance of buildings focus on energy demand and associated greenhouse gas emissions. They often neglect to consider the range of other resource demands and environmental impacts associated with buildings, including water. Studies that assess water use in buildings typically consider only operational water, which excludes the embodied water in building materials or the water associated with the mobility of building occupants. A new framework is presented that quantifies water requirements at the building scale (i.e. the embodied and operational water of the building as well as its maintenance and refurbishment) and at the city scale (i.e. the embodied water of nearby infrastructures such as roads, gas distribution and others) and the transport-related indirect water use of building occupants. A case study house located in Melbourne, Australia, is analysed using the new framework. The results show that each of the embodied, operational and transport requirements is nearly equally important. By integrating these three water requirements, the developed framework provides architects, building designers, planners and decision-makers with a powerful means to understand and effectively reduce the overall water use and associated environmental impacts of residential buildings.

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Multiple regression equations and response surfaces are used to describe the combined effects of body size, food concentration, acclimation temperature and season on physiological integrations such as the scope for growth, growth efficiency and O:N ratio. Maintenance and optimum ration levels are estimated for Mytilus edulis adapted to different factor combinations. Response surfaces illustrate the validity and sensitivity of the physiological integrations in quantifying the 'physiological condition' and the degree of stress experienced, under conditions ranging from near-optimal, through sub-lethal to lethal.