英语翻译原文
原文1
AUTOMATIC DEFLECTION AND TEMPERATURE
MONITORING OF
A BALANCED CANTILEVER CONCRETE BRIDGE
by Olivier BURDET, Ph.D.
Swiss Federal Institute of Technology, Lausanne, Switzerland
Institute of Reinforced and Prestressed Concrete
SUMMARY
There is a need for reliable monitoring systems to follow the evolution of the behavior of structures over time.
Deflections and rotations are values that reflect the overall structure behavior. This paper presents an innovative approach to the measurement of long-term deformations of bridges by use of inclinometers. High precision electronic inclinometers can be used to follow effectively long-term rotations without disruption of the traffic. In addition to their accuracy, these instruments have proven to be sufficiently stable over time and reliable for field conditions.
The Mentue bridges are twin 565 m long box-girder post-tensioned concrete highway bridges under construction in Switzerland. The bridges are built by the balanced cantilever method over a deep valley. The piers are 100 m high and the main span is 150 m. A centralized data acquisition system was installed in one bridge during its construction in 1997. Every minute, the system records the rotation and temperature at a number of measuring points. The simultaneous measurement of rotations and concrete temperature at several locations gives a clear idea of the movements induced by thermal conditions. The system will be used in combination with a hydrostatic leveling setup to follow the long-term behavior of the bridge.
Preliminary results show that the system performs reliably and that the accuracy of the sensors is excellent.
Comparison of the evolution of rotations and temperature indicate that the structure
responds to changes in air temperature rather quickly.
1.BACKGROUND
All over the world, the number of structures in service keeps increasing. With the development of traffic and the increased dependence on reliable transportation, it is becoming more and more necessary to foresee and anticipate the deterioration of structures. In particular, for structures that are part of major transportation systems, rehabilitation works need to be carefully planned in order to minimize disruptions of traffic. Automatic monitoring of structures is thus rapidly developing.
Long-term monitoring of bridges is an important part of this overall effort to attempt to minimize both the impact and the cost of maintenance and rehabilitation work of major structures. By knowing the rate of deterioration of a given structure, the engineer is able to anticipate and adequately define the timing of required interventions. Conversely, interventions can be delayed until the condition of the structure requires them, without reducing the overall safety of the structure.
The paper presents an innovative approach to the measurement of long-term bridge deformations. The use of high precision inclinometers permits an effective, accurate and unobtrusive following of the long-term rotations. The measurements can be performed under traffic conditions. Simultaneous measurement of the temperature at several locations gives a clear idea of the movements induced by thermal conditions and those induced by creep and shrinkage. The system presented is operational since August 1997 in the Mentue bridge, currently under construction in Switzerland. The structure has a main span of 150 m and piers 100 m high.
2. LONG-TERM MONITORING OF BRIDGES
As part of its research and service activities within the Swiss Federal Institute of Technology in Lausanne (EPFL), IBAP - Reinforced and Prestressed Concrete has been involved in the monitoring of long-time deformations of bridges and other structures for over twenty-five years [1, 2, 3, 4]. In the past, IBAP has developed a system for the measurement of long-term deformations using hydrostatic leveling [5, 6]. This system has been in successful service in ten bridges in Switzerland for approximately ten years [5,7]. The system is robust, reliable and
sufficiently accurate, but it requires human intervention for each measurement, and is not well suited for automatic data acquisition. One additional disadvantage of this system is that it is only easily applicable to box girder bridges with an accessible box.
Occasional continuous measurements over periods of 24 hours have shown that the amplitude of daily movements is significant, usually amounting to several millimeters over a couple of hours. This is exemplified in figure 1, where measurements of the twin Lutrive bridges, taken over a period of several years before and after they were strengthened by post-tensioning, are shown along with measurements performed over a period of 24 hours. The scatter observed in the data is primarily caused by thermal effects on the bridges. In the case of these box-girder bridges built by the balanced cantilever method, with a main span of 143.5 m, the amplitude of deformations on a sunny day is of the same order of magnitude than the long term deformation over several years.
Instantaneous measurements, as those made by hydrostatic leveling, are not necessarily representative of the mean position of the bridge. This occurs because the position of the bridge at the time of the measurement is influenced by the temperature history over the past several hours and days. Even if every care was taken to perform the measurements early in the morning and at the same period every year, it took a relatively long time before it was realized that the retrofit performed on the Lutrive bridges in 1988 by additional post-tensioning [3, 7,11] had not had the same effect on both of them.
Figure 1: Long-term deflections of the Lutrive bridges, compared to deflections measured in a 24-hour period Automatic data acquisition, allowing frequent measurements to be performed at an acceptable cost, is thus highly desirable. A study of possible solutions including laser-based leveling, fiber optics sensors and GPS-positioning was performed, with the conclusion that, provided that their long-term stability can be demonstrated, current types of electronic inclinometers are suitable for automatic measurements of rotations in existing bridges [8].
3. MENTUE BRIDGES
The Mentue bridges are twin box-girder bridges that will carry the future A1 motorway from Lausanne to Bern. Each bridge, similar in design, has an overall length of approximately 565 m, and a width of 13.46 m, designed to carry two lanes of traffic and an emergency lane. The bridges cross a deep valley with steep sides (fig. 2). The balanced cantilever design results from a bridge competition. The 100 m high concrete piers were built using climbing formwork, after which the
construction of the balanced cantilever started (fig. 3).
4. INCLINOMETERS
Starting in 1995, IBAP initiated a research project with the goal of investigating the feasibility of a measurement system using inclinometers. Preliminary results indicated that inclinometers offer several advantages for the automatic monitoring of structures. Table 1 summarizes the main properties of the inclinometers selected for this study.
One interesting property of measuring a structure’s rotations, is that, for a given ratio of maximum deflection to span length, the maximum rotation is essentially independent from its static system [8]. Since maximal allowable values of about 1/1,000 for long-term deflections under permanent loads are generally accepted values worldwide, developments made for box-girder bridges with long spans, as is the case for this research, are applicable to other bridges,
for instance bridges with shorter spans and other types of cross-sections. This is significant because of the need to monitor smaller spans which constitute the majority of all bridges.
The selected inclinometers are of type Wyler Zerotronic ±1°[9]. Their accuracy is 1 microradian (μrad), which corresponds to a rotation of one millimeter per kilometer, a very small value. For an intermediate span of a continuous beam with a constant depth, a mid-span deflection of 1/20,000 would induce a maximum rotation of about 150 μrad, or 0.15 milliradians (mrad).
One potential problem with electronic instruments is that their measurements may drift over time. To quantify and control this problem, a mechanical device was designed allowing the inclinometers to be precisely rotated of 180°in an horizontal plane (fig. 4). The drift of each inclinometer can be very simply obtained by comparing the values obtained in the initial and rotated position with previously obtained values. So far, it has been observed that the type of
inclinometer used in this project is not very sensitive to drifting.
5. INSTRUMENTATION OF THE MENTUE BRIDGES
Because a number of bridges built by the balanced cantilever method have shown an unsatisfactory behavior in service [2, 7,10], it was decided to carefully monitor the evolution of the deformations of the Mentue bridges. These bridges were designed taking into consideration recent recommendations for the choice of the amount of posttensioning [7,10,13]. Monitoring starting during the construction in 1997 and will be pursued after the bridges are opened to traffic in 2001. Deflection monitoring includes topographic leveling by the highway authorities, an hydrostatic leveling system over the entire length of both bridges and a network of inclinometers in the main span of the North bridge. Data collection is coordinated by the engineer of record, to facilitate comparison of measured values. The information gained from these observations will be used to further enhance the design criteria for that type of bridge, especially with regard to the amount of post-tensioning [7, 10, 11, 12, 13].
The automatic monitoring system is driven by a data acquisition program that gathers and stores the data. This system is able to control various types of sensors simultaneously, at the present time inclinometers and thermal sensors. The computer program driving all the instrumentation offers a flexible framework, allowing the later addition of new sensors or data acquisition systems. The use of the development environment LabView [14] allowed to leverage the large user base in the field of laboratory instrumentation and data analysis. The data acquisition system runs on a rather modest computer, with an Intel 486/66 Mhz processor, 16 MB of memory and a 500 MB hard disk, running Windows NT. All sensor data are gathered once per minute and stored in compressed form on the hard disk. The system is located in the box-girder on top of pier 3 (fig. 5). It can withstand severe weather conditions and will restart itself automatically after a power outage, which happened frequently during construction.
6. SENSORS
Figure 5(a) shows the location of the inclinometers in the main span of the North bridge. The sensors are placed at the axis of the supports (①an d⑤), at 1/4 and 3/4 (③an d④) of the span and at 1/8 of the span for②. In the cross section, the sensors are located on the North web, at a height corresponding to the center of gravity of the section (fig.5a). The sensors are all connected by a single RS-485 cable to the central data acquisition system located in the vicinity of inclinometer ①. Monitoring of the bridge started already during its construction. Inclinometers①,②and③were installed before the span was completed. The resulting measurement were difficult to interpret, however, because of the wide variations of angles induced by the various stages of this particular method of construction.
The deflected shape will be determined by integrating the measured rotations along the length of the bridge (fig.5b). Although this integration is in principle straightforward, it has been shown [8, 16] that the type of loading and possible measurement errors need to be carefully taken into account.
Thermal sensors were embedded in concrete so that temperature effects could be taken into account for the adjustment of the geometry of the formwork for subsequent casts. Figure 6 shows the layout of thermal sensors in the main span. The measurement sections are located at the same sections than the inclinometers (fig. 5). All sensors were placed in the formwork before concreting and were operational as soon as the formwork was removed, which was required for the needs of the construction. In each section, seven of the nine thermal sensor (indicated in solid black in fig. 6) are now automatically measured by the central data acquisition system.
7. RESULTS
Figure 7 shows the results of inclinometry measurements performed from the end of September to the third week of November 1997. All inclinometers performed well during that period. Occasional interruptions of measurement, as observed for example in early October are due to interruption of power to the system during construction operations. The overall symmetry of results from inclinometers seem to indicate that the instruments drift is
not significant for that time period. The maximum amplitude of bridge deflection during the observed period, estimated on the basis of the inclinometers results, is around 40 mm. More accurate values will be computed when the method of determination of deflections will have been
further calibrated with other measurements. Several periods of increase, respectively decrease, of deflections over several days can be observed in the graph. This further illustrates the need for continuous deformation monitoring to account for such effects. The measurement period was .busy. in terms of construction, and included the following operations: the final concrete pours in that span, horizontal jacking of the bridge to compensate some pier eccentricities, as well as the stressing of the continuity post-tensioning, and the de-tensioning of the guy cables (fig. 3). As a consequence, the interpretation of these measurements is quite difficult. It is expected that
further measurements, made after the completion of the bridge, will be simpler to interpret.
Figure 8 shows a detail of the measurements made in November, while figure.9 shows temperature measurements at the top and bottom of the section at mid-span made during that same period. It is clear that the measured deflections correspond to changes in the temperature. The temperature at the bottom of the section follows closely variations of the air temperature (measured in the shade near the north web of the girder). On the other hand, the temperature at the top of the cross section is less subject to rapid variations. This may be due to the high elevation of the bridge above ground, and also to the fact that, during the measuring period, there was little direct sunshine on the deck. The temperature gradient between top and bottom of the cross section has a direct relationship with short-term variations. It does not, however, appear to be related to the general tendency to decrease in rotations observed in fig. 8.
8. FUTURE DEVELOPMENTS
Future developments will include algorithms to reconstruct deflections from measured rotations. To enhance the accuracy of the reconstruction of deflections, a 3D finite element model of the entire structure is in preparation [15]. This model will be used to identify the influence on rotations of various phenomena, such as creep of the piers and girder, differential settlements, horizontal and vertical temperature gradients or traffic loads.
Much work will be devoted to the interpretation of the data gathered in the Mentue bridge. The final part of the research project work will focus on two aspects: understanding the very complex behavior of the structure, and determining the most important parameters, to allow a simple and effective monitoring of the bridges deflections.
Finally, the research report will propose guidelines for determination of deflections from measured rotations and practical recommendations for the implementation of measurement systems using inclinometers. It is expected that within the coming year new sites will be equipped with inclinometers. Experiences made by using inclinometers to measure deflections during loading tests [16, 17] have shown that the method is very flexible and competitive with other high-tech methods.
As an extension to the current research project, an innovative system for the measurement of bridge joint movement is being developed. This system integrates easily with the existing monitoring system, because it also uses inclinometers, although from a slightly different type. 9. CONCLUSIONS
An innovative measurement system for deformations of structures using high precision inclinometers has been developed. This system combines a high accuracy with a relatively simple implementation. Preliminary results are very encouraging and indicate that the use of inclinometers to monitor bridge deformations is a feasible and offers advantages. The system is reliable, does not obstruct construction work or traffic and is very easily installed. Simultaneous temperature measurements have confirmed the importance of temperature variations on the behavior of structural concrete bridges.
10. REFERENCES
[1] ANDREY D., Maintenance des ouvrages d’art: méthodologie de surveillance, PhD Dissertation Nr 679, EPFL, Lausanne, Switzerland, 1987.
[2] BURDET O., Load Testing and Monitoring of Swiss Bridges, CEB Information Bulletin Nr 219, Safety and Performance Concepts, Lausanne, Switzerland, 1993.
[3] BURDET O., Critères pour le choix de la quantitéde précontrainte découlant de l.observation de ponts existants, CUST-COS 96, Clermont-Ferrand, France, 1996.
[4] HASSAN M., BURDET O., FAVRE R., Combination of Ultrasonic Measurements and Load Tests in Bridge Evaluation, 5th International Conference on Structural Faults and Repair, Edinburgh, Scotland, UK, 1993.
[5] FAVRE R., CHARIF H., MARKEY I., Observation à long terme de la déformation des ponts, Mandat de Recherche de l’OFR 86/88, Final Report, EPFL, Lausanne, Switzerland, 1990.
[6] FAVRE R., MARKEY I., Long-term Monitoring of Bridge Deformation, NATO Research Workshop, Bridge Evaluation, Repair and Rehabilitation, NATO ASI series E: vol. 187, pp. 85-100, Baltimore, USA, 1990.
[7] FAVRE R., BURDET O. et al., Enseignements tirés d’essais de charge et d’observations à long terme pour l’évaluation des ponts et le choix de la précontrainte, OFR Report, 83/90, Zürich, Switzerland, 1995.
[8] DAVERIO R., Mesures des déformations des ponts par un système d’inclinométrie, Rapport de ma?trise EPFL-IBAP, Lausanne, Switzerland, 1995.
[9] WYLER AG., Technical specifications for Zerotronic Inclinometers, Winterthur, Switzerland, 1996.
[10] FAVRE R., MARKEY I., Generalization of the Load Balancing Method, 12th FIP Congress, Prestressed Concrete in Switzerland, pp. 32-37, Washington, USA, 1994.
[11] FAVRE R., BURDET O., CHARIF H., Critères pour le choix d’une précontrainte: application au cas d’un renforcement, "Colloque International Gestion des Ouvrages d’Art: Quelle Stratégie pour Maintenir et Adapter le Patrimoine, pp. 197-208, Paris, France, 1994. [12] FAVRE R., BURDET O., Wahl einer geeigneten Vorspannung, Beton- und Stahlbetonbau,
Beton- und Stahlbetonbau, 92/3, 67, Germany, 1997.
[13] FAVRE R., BURDET O., Choix d’une quantité appropriée de précontrainte, SIA D0 129, Zürich, Switzerland, 1996.
[14] NATIONAL INSTRUMENTS, LabView User.s Manual, Austin, USA, 1996.
[15] BOUBERGUIG A., ROSSIER S., FAVRE R. et al, Calcul non linéaire du béton armé et précontraint, Revue Fran?ais du Génie Civil, vol. 1 n° 3, Hermes, Paris, France, 1997.
[16] FEST E., Système de mesure par inclinométrie: développement d’un algorithme de calcul des flèches, Mémoire de ma?trise de DEA, Lausanne / Paris, Switzerland / France, 1997.
[17] PERREGAUX N. et al., Vertical Displacement of Bridges using the SOFO System: a Fiber Optic Monitoring Method for Structures, 12th ASCE Engineering Mechanics Conference, San Diego, USA, to be published,1998.
原文2
The Structure of Concrete Bridge
Pre-stressed concrete has proved to be technically advantageous, economically competitive, and esthetically superior bridges, from very short span structures using standard components to cable-stayed girders and continuous box girders with clear spans of nearly 100aft .Nearly all concrete bridges, even those of relatively short span, are now pre-stressed. Pre-casting, cast-in-place construction, or a combination of the two methods may be used .Both pre-tensioning and post tensioning are employed, often on the same project.
In the United States, highway bridges generally must-meet loading ,design ,and construction requirements of the AASHTO Specification .Design requirements for pedestrian crossings and bridges serving other purposes may be established by local or regional codes and specifications .ACI Code provisions are often incorporated by reference .
Bridges spans to about 100ft often consist of pre-cast integral-deck units ,which offer low initial cost ,minimum ,maintenance ,and fast easy construction ,with minimum traffic interruption .Such girders are generally pre-tensioned .The units are placed side by side ,and are often post-tensioned laterally at intermediate diaphragm locations ,after which shear keys between adjacent units are filled with non-shrinking mortar .For highway spans ,an asphalt wearing surface may be applied directly to the top of the pre-cast concrete .In some cases ,a cast-in-place slab is placed to provide composite action .
The voided slabs are commonly available in depths from 15 to 21 in .and widths of 3 to 4 ft .For a standard highway HS20 loading, they are suitable for spans to about 50 ft, Standard channel sections are available in depths from 21 to 35 in a variety of widths, and are used for spans between about 20 and 60 ft .The hollow box beams-and single-tee girders are intended for longer spans up to about 100 ft.
For medium-span highway bridges ,to about 120 ft ,AASHTO standard I beams are generally used .They are intended for use with a composite cast-in-place roadway slab .Such girders often combine pre-tensioning of the pre-cast member with post-tensioning of the composite beam after the deck is placed .In an effort to obtain improved economy ,some states have adopted more refined designs ,such as the State of Washington standard girders.
The specially designed pre-cast girders may be used to carry a monorail transit system .The finished guide way of Walt Disney World Monorail features a series of segments, each consisting of six simply supported pre-tensioned beams ,together to from a continuous structure .Typical spans are 100 to 110 ft . Approximately half of the 337 beams used have some combination of vertical and horizontal curvatures and variable super elevation .All beams are hollow, a feature achieved by inserting a styro-foam void in the curved beams and by a moving mandrel in straight beam production.
Pre-cast girders may not be used for spans much in excess of 120 ft because of the problems of transporting and erecting large, heavy units.
On the other hand ,there is a clear trend toward the use of longer spans for bridges .For elevated urban expressways ,long spans facilitate access and minimize obstruction to activities below .Concern for environmental damage has led to the choice of long spans for continuous viaducts . For river crossings, intermediate piers may be impossible because of requirements of navigational clearance.
In typical construction of this type, piers are cast-in-place, often using the slip-forming technique .A “hammerhead” section of box girder is often cast at the top of the pier, and construction proceeds in each direction by the balanced cantilever method. Finally, after the closing cast-in-place joint is made at mid-span, the structure is further post-tensioned for full continuity .Shear keys may be used on the vertical faces between segments, and pre-cast are glued with epoxy resin.
The imaginative engineering demonstrated by many special techniques has extended the range of concrete construction for bridges far beyond anything that could be conceived just a few years ago .In the United States, twin curved cast-in –place segmental box girders have recently been completed for of span of 310 ft over the Eel River in northern California .Preliminary design has been completed for twin continuous box girders consisting of central 550 ft spans flanked by 390 ft side spans.
Another form of pre-stressed concrete bridge well suited to long spans is the cable-stayed box girder .A notable example is the Chaco-Corrientes Bridge in Argentina .The bridges main span of 804 ft is supported by two A-frame towers, with cable stays stretching from tower tops to points along the deck .The deck itself consists of two parallel box girders made of pre-cast sections erected using the cantilever method .The tensioned cables not only provide a vertical
reaction component to support the deck ,but also introduce horizontal compression to the box girders ,adding to the post-tensioning force in those members .
Stress-ribbon Bridge pioneered many years ago by the German engineer Ulrich Finsterwalder. The stress-ribbon bridge carries a pipeline and pedestrians over the Rhine River with a span of 446 ft .The superstructure erection sequence was to (a) erect two pairs of cables, (b) place pre-cast slabs forming a sidewalk deck and a U under each of the sets of cables, and (c) cast-in-place concrete within the two Us. The pipeline is placed atop supports at railing height, off to one side, which greatly increases the wind speed of the structure.
It is appropriate in discussing bridge forms to mention structural esthetics .The time is past when structures could be designed on the basis of minimum cost and technical advantages alone .Bridge structures in particular are exposed for all to see .To produce a structure that is visually offensive ,as has occurred all too often in the past, is an act professional irresponsibility .Particularly for major spans ,but also for more ordinary structures ,architectural advice should be sought early in conceptual stage of the design process.
英语原文及其翻译
Exploring Filipino School Counselors’ Beliefs about Learning Allan B. I. Bernardo [Abstract] School reform efforts that focus on student learning require school counselors to take on important new roles as advocates of student learning and achievement.But how do school counselors understand the process of learning? In this study, we explore the learning beliefs of 115 Filipino school counselors who indicated their degree of agreementwith 42 statements about the process of learning and the factors thatinfluence this process.A principal components analysis of the responses to the 42 statements suggested three factors:(F1)social-cognitive constructivist beliefs, (F2) teacher-curriculum-centered behaviorist beliefs,and (F3) individual difference factors.The preliminary results are briefly discussed in terms of issues related to how Filipino school counselors’ conceptions of learning may guide their strategies for promoting student learning and achievement. [Key words]beliefs about learning, conceptions of learning, school counselors, student learning, Philippines School reform efforts in different parts of the world have focusedon students’learning. In particular,most school improvement programsnow aim to ensure that students acquire the high-level knowledge and skills that help them to thrive in today’s highly competitive globaleconomy (e.g., Lee & Williams, 2006). I n this regard, school reform programs draw from various contemporary theories and research on learning (e.g.,Bransford,Brown, & Cocking, 1999; Lambert & McCombs, 1998).The basic idea is that all school improvement efforts should be directed at ensuring students achieve high levels of learning or attainment of well-defined curricular objectives and standards.For example, textbooks (Chien & Young, 2007), computers and educational technology (Gravoso, 2002; Haertnel & Means, 2003;Technology in Schools Task Force, 2003), and educational assessment systems (Black & Wiliam2004; Cheung & Ng, 2007; Clark, 2001; Stiggins, 2005) are being reconsidered as regards how they can effectively provide scaffolds and resources for advancing student learning. Likewise,the allocation and management of a school’s financial resources are assessed in terms ofwhether these are effectively mobilized and utilized towards improving student learning (Bolam, 2006; Chung & Hung, 2006; Retna, 2007). In this regard, some advocates have also called for an examination of the role of school counselors in these reform efforts (Herr, 2002). Inthe United States, House and Hayes (2002) challenged school counselors to take proactive leadership roles in advocating for the success of all
蓝梅主编 给排水科学与工程专业英语部分课文翻译中文版
第四单元给水系统 一般来说，供水系统可划分为四个主要组成部分:（1）水源和取水工程（2）水处理和存储（3）输水干管和配水管网。常见的未处理的水或者说是原水的来源是像河流、湖泊、泉水、人造水库之类的地表水源以及像岩洞和水井之类的地下水源。修建取水构筑物和泵站是为了从这些水源中取水。原水通过输水干管输送到自来水厂进行处理并且处理后的出水储存到清水池。处理的程度取决于原水的水质和出水水质要求。有时候，地下水的水质是如此的好以至于在供给给用户之前只需消毒即可。由于自来水厂一般是根据平均日需求流量设计的，所以，清水池为水需求日变化量提供了一个缓冲区。 水通过输水干管长距离输送。如果输水干管中的水流是通过泵所产生的压力水头维持的，那么我们称这个干管为增压管。另外，如果输水干管中的水流是靠由于高差产生的可获得的重力势能维持的，那么我们称这个干管为重力管。在输水干管中没有中间取水。与输水干管类似，在配水管网中水流的维持要么靠泵增压，要么靠重力势能。一般来说，在平坦地区，大的配水管网中的水压是靠泵提供的，然而，在不平坦的地区，配水管网中的压力水头是靠重力势能维持的。 一个配水管网通过引入管连接配水给用户。这样的配水管网可能有不同的形状，并且这些形状取决于这个地区的布局。一般地，配水管网有环状或枝状的管道结构，但是，根据当地城市道路和街区总体布局计划，有时候环状和枝状结构合用。城市配水管网大多上是环状形式，然而，乡村地区的管网是枝状形式。由于供水服务可靠性要求高，环状管网优于枝状管网。 配水管网的成本取决于对管网的几何形状合适的选择。城市计划采用的街道布局的选择对提供一个最小成本的供水系统来说是重要的。环状管网最常见的两个供水结构是方格状、环状和辐射状；然而，我们不可能找到一个最佳的几何形状而使得成本最低。 一般地，城镇供水系统是单入口环状管系统。如上所说，环状系统有一些通过系统相互连接的管道使得通过这些连接接的管道，可以供水到同一个需水点。与枝状系统不同，在环状系统中，由于需水量在空间和时间上的变化，管道中的水流方向并非不变。 环状管网可为系统提供余量，提高系统应对局部变化的能力，并且保证管道故障时为用户供水。从水质方面来说，环状形状可减少水龄，因此被推广。管道的尺寸和配水系统的设计对减少水龄来说是重要的因素。由于多方向水流模式和系统中流动模式随时间的变化，水不会停留在一个地方，这样减少了水龄。环状配水系统的优缺点如表4.1所述。 优点:1.Minimize loss of services.as main breaks can be isolated due to multidirectional flow to demand points.2.Reliability for fire protection is higher due to redundancy in the system.3.Likely to meet increase in water demand -higher capacity and lower velocities.4.Better residual chlorine due to in line mixing and fewer dead ends. 5.Reduced water age. 在文献中曾记载过，只考虑最低成本设计的环状管网系统会转化成树状似的结构，这一做法导致在最终的设计中失去最初的几何形状。环状保证了系统的可靠性。因此，一个只考虑最低成本为依据的设计打败了在环状管网中所提供的基本功能。有文献记载设计环状管网系统的方法。尽管这个方法也是仅以考虑最低成本为基础，它通过对管网中所有管道最优化规划从而保持了管网的环状结构。
文献翻译英文原文
https://www.wendangku.net/doc/6610635976.html,/finance/company/consumer.html Consumer finance company The consumer finance division of the SG group of France has become highly active within India. They plan to offer finance for vehicles and two-wheelers to consumers, aiming to provide close to Rs. 400 billion in India in the next few years of its operations. The SG group is also dealing in stock broking, asset management, investment banking, private banking, information technology and business processing. SG group has ventured into the rapidly growing consumer credit market in India, and have plans to construct a headquarters at Kolkata. The AIG Group has been approved by the RBI to set up a non-banking finance company (NBFC). AIG seeks to introduce its consumer finance and asset management businesses in India. AIG Capital India plans to emphasize credit cards, mortgage financing, consumer durable financing and personal loans. Leading Indian and international concerns like the HSBC, Deutsche Bank, Goldman Sachs, Barclays and HDFC Bank are also waiting to be approved by the Reserve Bank of India to initiate similar operations. AIG is presently involved in insurance and financial services in more than one hundred countries. The affiliates of the AIG Group also provide retirement and asset management services all over the world. Many international companies have been looking at NBFC business because of the growing consumer finance market. Unlike foreign banks, there are no strictures on branch openings for the NBFCs. GE Consumer Finance is a section of General Electric. It is responsible for looking after the retail finance operations. GE Consumer Finance also governs the GE Capital Asia. Outside the United States, GE Consumer Finance performs its operations under the GE Money brand. GE Consumer Finance currently offers financial services in more than fifty countries. The company deals in credit cards, personal finance, mortgages and automobile solutions. It has a client base of more than 118 million customers throughout the world
建筑工程及给排水专业中英文对照翻译
Laminar and Turbulent Flow Observation shows that two entirely different types of fluid flow exist. This was demon- strated by Osborne Reynolds in 1883 through an experiment in which water was discharged from a tank through a glass tube. The rate of flow could be controlled by a valve at the outlet, and a fine filament of dye injected at the entrance to the tube. At low velocities, it was found that the dye filament remained intact throughout the length of the tube, showing that the particles of water moved in parallel lines. This type of flow is known as laminar, viscous or streamline, the particles of fluid moving in an orderly manner and retaining the same relative positions in successive cross- sections. As the velocity in the tube was increased by opening the outlet valve, a point was eventually reached at which the dye filament at first began to oscillate and then broke up so that the colour was diffused over the whole cross-section, showing that the particles of fluid no longer moved in an orderly manner but occupied different relative position in successive cross-sections. This type of flow is known as turbulent and is characterized by continuous small fluctuations in the magnitude and direction of the velocity of the fluid particles, which are accompanied by corresponding small fluctuations of pressure. When the motion of a fluid particle in a stream is disturbed, its inertia
英文翻译(原文)
GRA VITY RETAINING?WALL 1. INTRODUCTION Retaining walls are structures used to provide stability for earth or other material where conditions disallow the mass to assume its natural slope, and are commonly used to hold back or support soilbanks,coal or ore piles, and water. Retaining walls are classified, based on the method of achieving stability, into six principal types (Fig.1). The gravity-wall depends upon its weight, as the name implies, for stability. The cantilever wall is a reinforced-concrete wall that utilizes cantilever action to retain the mass behind the wall from assuming a natural slope. Stability of this wall is partially achieved from the weight of soil on the heel portion of the base slab. A counterfort retaining wall is similar to a cantilever retaining wall, except that it is used where the cantilever is long or for very high pressures behind wall and has counterforts, which tie the wall and base together, built at intervals along the wall to reduce the bending moments and sheers. As indicated in Fig.1c, the counterfort is behind the wall and subjected to tensile forces. A buttressed retaining wall is similar to a counterfort wall, except that the bracing is in front of the wall and is in compression instead of tension. Two other types of walls not considered further are crib walls, which are built-up members of pieces of precast concrete, metal, or timber and are supported by anchor pieces embedded in the soil for stability, and semigravity walls, which are walls intermediate between a true gravity and a cantilever wall. (a)(b)(e)
英语原文及翻译
高速视频处理系统中的信号完整性分析 摘要：结合高速DSP图像处理系统讨论了高速数字电路中的信号完整性问题，分析了系统中信号反射、串扰、地弹等现象破坏信号完整性的原因，通过先进IS工具的辅助设计，找出了确保系统信号完整性的具体方法。 关键词：高速电路设计信号完整性 DSP系统 深亚微米工艺在IC设计中的使用使得芯片的集成规模更大、体积越来越小、引脚数越来越多；由于近年来IC工艺的发展，使得其速度越来越高。从而，使得信号完整性问题引起电子设计者广泛关注。 在视频处理系统中，多维并行输入输出信号的频率一般都在百兆赫兹以上，而且对时序的要求也非常严格。本文以DSP图像处理系统为背景，对信号完整性进行准确的理论分析，对信号完整性涉及的典型问题[1]——不确定状态、传输线效应、反射、串扰、地弹等进行深入研究，并且从实际系统入手，利用IS仿真软件寻找有效的途径，解决系统的信号完整性问题。 1 系统简介 为了提高算法效率，实时处理图像信息，本图像处理系统是基于DSP+FPGA结构设计的。系统由SAA7111A视频解码器、TI公司的TMS320C6701 DSP、Altera公司的EPlK50QC208 FPGA、PCI9054 PCI接口控制器以及SBRAM、SDRAM、FIFO、FLASH等构成。FPGA是整个系统的时序控制中心和数据交换的桥梁，而且能够对图像数据实现快速底层处理。DSP是整个系统实时处理高级算法的核心器件。系统结构框图如图1所示。 在整个系统中，PCB电路板的面积仅为15cm×l5cm，系统时钟频率高达167MHz，时钟沿时间为0．6ns。由于系统具有快斜率瞬变和极高的工作频率以及很大的电路密度，使得如何处理高速信号问题成为一个制约设计成功的关键因素。 2 系统中信号完整性问题及解决方案 2．1 信号完整性问题产生机理 信号的完整性是指信号通过物理电路传输后，信号接收端看到的波形与信号发送端发送的波形在容许的误差范围内保持一致，并且空间邻近的传输信号间的相互影响也在容许的范围之内。因此，信号完整性分析的主要目标是保证高速数字信号可靠的传输。实际信号总是存在电压的波动，如图2所示。在A、B两点由于过冲和振铃[2]的存在使信号振幅落入阴影部分的不确定区，可能会导致错误的逻辑电平发生。总线信号传输的情况更加复杂，任何一个信号发生相位上的超前或滞后都可能使总线上数据出错，如图3所示。图中，CLK为时钟信号，D0、D1、D2、D3是数据总线上的信号，系统允许信号最大的建立时间[1]为△t。在正常情况下，D0、D1、D2、D3信号建立时间△t1<△t，在△t时刻之后数据总线的数据已稳定，系统可以从总线上采样到正确的数据，如图3(a)所示。相反，当信号D1、D2、D3受过冲和振铃等信号完整问题干扰时，总线信号就发生
水文与水资源专业英语文章翻译
3单元 地下水位的高低可在一年内大幅波动，下降和上升后，在干燥的季节，降水期。因此，为了保证连续供水，井应穿透许多米水位以下。当水从井里抽水，它在水面产生抑郁，大致锥形的形状，称为漏斗。如果抽重，水表不仅可以降低周围的好但还可延伸到大面积。这在美国西部的部分是这样的。在这种情况下，可以说，地下水被“开采”。即使抽人立即停止，它可能需要数百年的地下水得到补充。下面的例子说明了这一点： 例如，在干燥的美国西南部，含水层补给是每年只有1英寸深的水的十分之二点位置。在这些地区，这是不寻常的泵两英尺或更多的水用于灌溉和其他用途的每年。在这个简单的例子，如果整个含水层抽水的速度，每年的开采量将相当于120年和十年的补给，泵将1200年积累的水。在泵送期间新补给可以忽略不计。机械问题和经济因素阻止完全脱水的含水层，但原则上是有效的例子。 短期承压是适用于任何情况，地下水位上升，在一个以上的水平，这是最初遇到的。这样的情况发生，两个条件必须满足：（1）水，必须限制在一个含水层，是倾斜的，一端暴露在表面，在那里可以得到水；和（2）防渗层，上面和下面的含水层，必须防止水逃避，这样一层被窃听，被上面的水的重量产生的压力会使水上升。如果没有摩擦，井里的水会上升到顶部的水位。含水层。 自流系统作为管道，将水从很远的偏远地区的充电放电点。这样水倒在威斯康星州中部年前现在是从地面和社区许多英里远，伊利诺斯。在南达科他州这样的系统已经从西部的黑山带水，向东跨越国家。在不同的尺度上，城市供水系统可能是人为的自流系统的例子。水塔，为抽水，可能是补给区，管道的承压含水层，在家中的自流井的水龙头。 4单元 矿产勘查在世界表明温度在深油、矿产品通常会增加在地表以下深度增加。在这样的情况下增加温度约0.6度，平均每30米。因此，当地下水在深循环，它变得激烈，如果它上升到表面，水是温泉。一些温泉水在美国，特别是在东部，加热这种方式。在美国，绝大多数的温泉发现于西方。这种分布的原因是，大部分温泉的热源是冷却的火成岩，它是在西方，火成活动已经最近。 间歇泉是间歇性的温泉或喷泉，水柱喷射的伟大力量在不同的时间间隔，通常上升30-60米。水流停止后，一列蒸汽冲出，通常以雷鸣般的轰鸣声。这或许是世界上最著名的间歇泉是黄石公园的老忠实喷发，大约每小时一次。间歇泉也在世界的其他地区，包括冰岛和新西兰，在那里长期间歇泉，意为“喷泉”或“井喷”这个词。 间歇泉时，地下水是地下室加热。室底部，水在巨大的压力下，由于上覆水的重量。因此，一个100度以上的温度就会沸腾所需的前。例如，在一个300米的室内水下必须达到一个温度近230度才开。加热使水膨胀，其结果是某些流出的顶部。这减少了压力，和水变成蒸汽，使间歇泉喷发。 从温泉和间歇泉地下水通常包含在解决方案比其他来源的地下水多材料因为热水比冷水更有效的溶解。当水中含有大量溶解的二氧化硅，硅华沉积在春天。石灰石，方解石的一种，是在石灰岩地区温泉特色存款。一些温泉含硫磺。除了使水的味道不好，硫发出难闻的气味。毫无疑问，臭蛋的春天，内华达州，这种情况。 11单元 一种污染物，是任何物质，生物或化学。在一个可识别的过量的有害的其他理想的生物。在这个框架内，过量的重金属如发汞；某些放射性同位素；氮，磷，钠；和其他有用的，甚至是必要的元素，以及某些致病性细菌和病毒污染物。在某些情况下，材料可作为一种污染物，世界人口中的一段特别的虽然它对其他部分不被认为是有害的。例如，在适当的复合氮超标有害于婴儿，但少了很多成年人如果在所有。在这样的方式，过多的钠盐通常不是有害的，但它可以制约医疗原因盐的摄入饮食的某些人。 不同的物理，地质，生物环境与地下水污染与地表水污染相比是显著的。在后者中，流量和氧气和阳光可用液压，随着速度的过程中污染物的稀释和扩散发生，明显不同于地下水，在污染物降解菌的机会通常局限于土壤或几英尺以下。此外，通过何种渠道地下水运动是非常小的和可变的。由此，显而易见的是，移动速度大大降低，除非，也许，在大的解决渠道内石灰石，以及分散和稀释的机会是非常有限的。此外，地下水通常缺乏氧气，这是造成好氧微生物的种类有帮助但这可能提供了一个“幸福之家”厌氧品种。 大多数土壤和岩石物理过滤出固体的能力，包括污染的固体，是公认的。然而，这种能力会随不同的大小，形状，和滤料颗粒的安排，在选定的沙子和其他材料在水过滤厂使用证明。也知道，但也许不那么普遍，是粘土和其他矿物捕获和交换的一些元素和化合物的能力时，他们游离在溶液中的正或负电荷的元素或化合物。这样的交流，随着吸附和沉淀过程中，污染物的捕获是重要的。这些过程有能力定义的单位是可逆的。他们也可以很容易地在设计设施正确的污染问题所依托的地质环境，土壤和岩石忽视治疗；这种疏忽可能造成地下水污染。这是特别重要的在污水土地应用。 很多猜测，争论，研究发生的地下水污染。地下水污染的主要关注的是化学元素，化合物的引入，和微生物，不含水层，可用于饮用水或是自然发生的，不仅因为该含水层的降解也因为在检测的难度，长期居住，和难度和费用含水层恢复。强有力的论点是，任何废物或可能的污染物应允许进入地下水系统的任何部分。这是一个不可能实现的梦想。相反，答案在于更多的了解自然过程处理废弃物的保证时，土壤和岩石是不能够处理，存储，或回收废物，我们可以发展过程使污染物处理，储存，或可回收。 Extracting and distinguishing environmental change information with high resolution form groundwater and sediments of groundwater system has been the major trend of groundwater sciences towards environmental sciences, This is very useful for forecasting environmental change.4从地下水及其沉积物中提取高分辨率的环境变化信息，实现对环境变化的预警功能是地下水科学向环境科学延伸的重要方向。5而随着全球淡水资源紧缺的形势不断恶化，全球环境变化，特别是全球气候变化对地下水资源的影响成为水文地质研究的新课题。5 With fresh water shortage increasingly serious, the research on effect of globle environmental change, especially globle climate change in groundwater resource has become a new area for hydrogeological research. 4depleted in K and SO4 井的出水量与含水层的渗透系数成正比。 Well water yield is proportional to the transmissivity of a aquifer. 1、分布在这个深层碳酸岩含水层中的地下热水的温度是60℃-90℃。 2、Temperature of the thermal groundwater in the deep-seated carbonate aquifer occurring in this area ranges from 60℃ 3、所有观测井水位的季节性波动可以用研究区降水量的季节性变化来解 4、Seasonal fluctuations in water table in observation wells are interpreted by seasonal changes of/in precipitation in study areas.
科普版英语六年级下册课文及翻译 (直接打印版)
Lesson 1 I’m not feeling well. Let’s talk （M=Mom, T= Tom） M: What,'s the matter, Tom T: I'm not feeling well, Mom M: Do you have a cold T: Yes, I think so. Could you give me some water, please M: Here you are. T: Thank you, Mom. M: Tom, you must go and see a doctor. T: OK, Mom. M: It's cold outside. You must wear your coat. T: OK, Mom. Could you pass me my coat,please M: Here you are. T: Thank you, Mom M: Tell me your teacher's number. I'll call him and tell him you are sick. T: OK. Here it is. 译文 (M=妈妈,T=汤姆) 妈妈:怎么了,汤姆 汤姆:我感觉不舒服,妈妈。 妈妈:你感冒了吗 汤姆:是的,我想是这样的。您能给我一些水吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:汤姆,你必须去看医生. 汤姆:好的,妈妈。 妈妈:外面很冷。你必须穿你的外套。 汤姆:好的,妈妈。您能把我的外套递给我吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:告诉我你老师的电话号码。我将给他打电话告诉他你生病了。
英语翻译专业必翻经典文章英文原文参考译文
文档简介 一，英语翻译经典文章之英文原稿二，中文翻译：这篇英语文章的最好翻译版本！不是俺说的，是俺老师说哒！！ 英文原稿Brian It seems my only request (“please, let me sleep”) is not clear enough, so I made this simple table that can help you when you’re in doubt. Especially during the night
中文翻译小子： 我只想好好地睡觉，你不明白吗？！所以，我做了这个简表。当你不知道怎么办时，特 别是在晚上的时候，你可以看看它。 具体情况行动指南 1，我正在睡觉禁止进入 2，你不确定我是否睡觉，你想搞清楚管你“鸟”事；禁止进入 3，你嗑了药，想奔向我的床你他妈的滚远点 4，你在youtube上看了一个超赞的视频，禁止进入；在脸书上把链接发给我想让我看看 5，就算第三次世界大战开始了管我屁事，他妈的别进来 6，你和你的基友们想和我“玩玩”抱歉，直男一枚。不要碰我的任何东西，门都别碰 7，你想整理我的房间我谢谢你了！我自己会打扫 8，普京宣布同性婚姻合法化终于等到“它”！还好你没放弃！还是不要来我房里！ 9，我不在家进我房间，想都别想 10，白天，我在家。你敲了门，我说“请进” 你可以进来了 福利放送！！
如果你已经看到了这里，那么说明你应该是英文爱好者哦。 下面有一些非常实用，我精心整理的英文资料，你一定用得到！快去看看吧！ 一，最常用英语翻译政治文体句型总结大全完美版 二，英文合同翻译最常用句型总结专业版 三，英语毕业论文提纲模板优秀完整详细无敌版
土木工程专业英语课文原文及对照翻译
土木工程专业英语课文原 文及对照翻译 Newly compiled on November 23, 2020
Civil Engineering Civil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities. 土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。 Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities. 土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。他们也建造私有设施，比如飞机场，铁路，管线，摩天大楼，以及其他设计用作工业，商业和住宅途径的大型结构。此外，土木工程师还规划设计及建造完整的城市和乡镇，并且最近一直在规划设计容纳设施齐全的社区的空间平台。 The word civil derives from the Latin for citizen. In 1782, Englishman John Smeaton used the term to differentiate his nonmilitary engineering work from that of the military engineers who predominated at the time. Since then, the term civil engineering has often been used to refer to engineers who build public facilities, although the field is much broader 土木一词来源于拉丁文词“公民”。在1782年，英国人John Smeaton为了把他的非军事工程工作区别于当时占优势地位的军事工程师的工作而采用的名词。自从那时起，土木工程学被用于提及从事公共设施建设的工程师，尽管其包含的领域更为广阔。 Scope. Because it is so broad, civil engineering is subdivided into a number of technical specialties. Depending on the type of project, the skills of many kinds of civil engineer specialists may be needed. When a project begins, the site is surveyed and mapped by civil engineers who locate utility placement—water, sewer, and power lines. Geotechnical specialists perform soil experiments to determine if the earth can bear the weight of the project. Environmental specialists study the project’s impact on the local area: the potential for air and
英文翻译原文
南京师范大学泰州学院 英文翻译原文 年级： 2011级学号：12110330 姓名：申佳佳 系部：信息工程学院 专业：通信工程 题目：基于C51的数字测速仪设计与仿真 指导教师：焦蓬蓬 2015 年 4 月 5 日
Linux - Operating system of cybertimes Though for a lot of people , regard Linux as the main operating system to make u p huge work station group, finish special effects of " Titanic " make , already can be re garded as and show talent fully. But for Linux, this only numerous news one of. Rece ntly, the manufacturers concerned have announced that support the news of Linux to i ncrease day by day, users' enthusiasm to Linux runs high unprecedentedly too. Then, Linux only have operating system not free more than on earth on 7 year this piece wh at glamour, get the favors of such numerous important software and hardware manufa cturers as the masses of users and Orac le , Informix , HP , Sybase , Corel , Intel , Net scape , Dell ,etc. , OK? 1.The background of Linux and characteristic Linux is a kind of " free (Free ) software ": What is called free, mean users can o btain the procedure and source code freely , and can use them freely , including revise or copy etc.. It is a result of cybertimes, numerous technical staff finish its research a nd development together through Inte rnet, countless user is it test and except fault , c an add user expansion function that oneself make conveniently to participate in. As th e most outstanding one in free software, Linux has characteristic o f the following: (1)Totally follow POSLX standard, expand the network operating system of sup porting all AT&T and BSD Unix characteristic. Because of inheritting Unix outstandi ng design philosophy , and there are clean , stalwart , high-efficient and steady kernels , their all key codes are finished by Li nus Torvalds and other outstanding programmer s, without any Unix code of AT&T or Berkeley, so Linu x is not Unix, but Linux and Unix are totally compatible. (2)Real many tasks, multi-user's system, the built-in n etwork supports, can be with such seamless links as NetWare , Windows NT , OS/2 , Unix ,etc.. Network in various kinds of Unix it tests to be fastest in comparing and ass ess efficiency. Support such many kinds of files systems as FAT16 , FAT32 , NTFS , E x t2FS , ISO9600 ,etc. at the same time .