多股等羽流的速度与流量修正及其对高大空间自然通风的影响

根据动量叠加原理对多股等羽流的相互作用进行了研究,定义了三个速度修正系数和流量修正系数。通过数值计算,分析了平均速度修正系数、流量修正系数随高度和热源间距的变化规律。将相互作用的多股等羽流应用于一种高大空间二区自然通风模型,计算结果显示多股等羽流的相互作用提高了热分层高度,增加了通风量,对高大空间自然通风的影响十分明显。     

降低水蒸气流量测量误差的应用方法研究

通过对现场水蒸气流量计量装置和测量系统内相关导压管线、设备使用情况进行分析，总结出一套适合本企业的能有效降低流量测量误差的方法和措施，并已成功运用。     

大比降高速水流排水管水力计算

大比降排水管水流通常为高速水流,其水力设计已经超过排水设计规范范畴。以实际工程为例,指出该类管道不宜按照有压管路或明渠均匀流计算公式进行水力计算,应按照掺气水流计算,这为实际工程设计提供了参考依据。     

旋风除尘器内流场测试中三维速度的计算方法

在利用五孔探针测试旋风除尘器内流场时，探针标定情况及实验模型不同，所应采用的一一维速度计算公式也就不同，这一点在测试研究中常常被饭视，从而得出错误结论而该错误又不易被发现。给出了各种情况下三维速度的计算公式及探针测也布和β角正负规定的自我判别方法。     

大渗量高流速渗漏的灌浆堵漏技术

为解决大渗量、高流速下的渗漏问题，对土工模袋材料和丙烯酸盐类灌浆材料及其灌浆堵漏技术进行了室内试验，并通过成功的工程实例证明所述技术的有效性。     

橡胶混凝土抗压强度与超声波波速关系的试验研究

利用超声波混凝土无损检测技术,对3种不同粒径、不同掺量的橡胶粉改性高强混凝土试件进行了超声波检测,并同时进行了抗压强度试验,由试验数据回归出了抗压强度和超声波波速之间的关系,可为橡胶改性高强混凝土的强度测试提供一定的技术参考.     

骨料级配对透水性混凝土强度及超声波速度的影响

透水性混凝土与普通混凝土不同,由于含有大量的连通孔隙使强度变得很低.所以,如何提高强度是透水性混凝土的关键技术之一.本文用改变骨料级配的方法研究了透水性混凝土的强度、超声波速度与孔隙率之间的关系.     

The effects of changing water flow velocity on the formation of biofilms and water quality in pilot distribution system consisting of copper or polyethylene pipes

We studied the effects of flow velocity on the formation of biofilms and the concentration of bacteria in water in copper and plastic (polyethylene, PE) pipes. The formation of biofilms increased with the flow velocity of water. The increase in microbial numbers and contents of ATP was clearer in the PE pipes than in the copper pipes. This was also seen as increased consumption of microbial nutrients in the pipeline system. This indicates that the mass transfer of nutrients is in major role in the growth of biofilms. However, the increased biomass of biofilms did not affect microbial numbers in the water. Rapid changes in water flow rate resuspended biofilms and sediments which increased the concentrations of bacteria and copper in water. The disturbance caused by the changing water flow was also seen as an increase in the particle counts and water turbidity recorded with online instrumentation.     

温湿度异常引起混凝土收缩测试误差的修正

研究了混凝土收缩测试过程中环境温度和湿度异常波动引起的收缩测试误差。结果表明热胀冷缩是温度影响收缩测试的主要原因,引起的误差超过混凝土的收缩值,对收缩测试结果影响很大。热胀冷缩变形是可逆的,可通过在总变形中减去热膨胀变形对收缩测试结果进行修正,消除温度误差。环境相对湿度异常引起混凝土内部相对湿度变化,进而导致毛细孔压力改变,引起收缩测试误差。湿度异常对收缩的影响与相对湿度差值和持续时间成正比,与试件最小截面尺寸成反比,可据此对测试误差进行修正。     

地铁车站施工监测水准测量误差来源及控制

依据南京地铁二号线某车站基坑周边环境监测的工作经验,分析了水准测量误差的来源,并提出了具体的解决方法,实践证明,这些方法均能有效降低测量中的误差,为同类工程提供了参考.     

某高校主楼工程打桩前后的波速对比测试

讨论了打桩对场地类别的影响和减轻震害的机理。通过对淮阴工学院主楼地基在打桩前后的场地剪切波速对比测试,发现打桩有改变场地类别的可能,建议《规范》^[1]增加对打桩建筑特别是打桩较密的高层建筑在打桩后,应再次进行剪切波速测试并对比场地类别的改变等内容,从而提高工程设计的经济效益和社会效益。     

暖通流场测试技术的发展与展望

与传统接触式流量测试方法相比较,介绍了非接触式流量测试方法,重点介绍了激光多普勒技术(LDA)和粒子图像测试技术(PIV)在流场测试中运用的原理。     

塔里木沙漠公路沿线地下水流速流向测定

本文在沿塔里木沙漠公路设置的监测井中,利用日本Alec Electronics公司生产的MODELGFD4型地下水流向流速计,对塔克拉玛干沙漠腹地的地下水流速流向作了一次测定,结果显示：沙漠公路沿线地下水平均流速为：0．01cm／min,即52．56m／a;地下水流动方向在沙漠北部主要以ENE方向为主,沙漠中部除个别井点外主要以EN方向为主,沙漠南部尼雅河下游监测井中流向由ENN方向和WNN方向构成,牙通古斯河下游观测井处以ESS方向为主。地下水流动方向的控制因素主要有：盆地总体地形因素、河流流量变化、局部地形因素。     

隧道大变形段落的监控量测与加固方案研究

以六盘山隧道为例,详细介绍了在隧道大变形段落的监控量测实施过程,并对隧道围岩发生的大变形提出了针对性的加固处理方案,实践证明采用该加固处理措施非常有效,可以为类似的隧道施工提供借鉴。     

黄土双线法湿陷性试验的结果修正及误差分析

论述了黄土的湿陷特性及对工程的影响,重点介绍了黄土双线法湿陷性试验的试验过程及数据修正,列举实例阐述试验结果的计算,分析了试验中产生误差的因素,提出了减少误差的办法,以达到指导实践的目的。     

A wireless sensor system for structural health monitoring with guided ultrasonic waves and piezoelectric transducers

Piezoelectric transducers are widely used for structural health monitoring (SHM) applications. Low weight and small dimensions are only two of the several advantages of piezoelectric transducers. However, these advantages are weakened by using wired connections for supplying the piezoelectric transducers. Besides the additional weight, a long wire connection can have an influence on the measured capacitance. Due to the aforementioned disadvantages, researchers developed different wireless solutions for SHM applications in the last 10 years. In this paper, we present a wireless SHM system, which is designed for SHM applications with piezoelectric transducers and guided ultrasonic waves (GUW). The first part in this paper describes the different parts of the wireless SHM system. One novelty ofthe proposed wireless system is that every wireless signal-processing unit (SPU) in the network can be used for exciting the piezoelectric transducer and also for measuring the voltage signals coming from the piezoelectric transducer. Finally, the paper presents a laboratory test on an aluminium/hardfoam sandwich plate with a removable artificial defect to accurately assess the performance merits and weaknesses of the wireless sensor network.     

监控量测与信息反馈在公路隧道施工中的应用

结合秦岭终南山公路隧道施工，提出了现场监控量测的实施方案，并对该方案的监测仪器、测点布置、量测断面间距、施工监测、量测频率及量测数据采集整理进行了介绍，并对其量测数据进行了分析和信息反馈，以优化设计和施工方案，为今后超长度、大埋深隧道的施工积累了经验。     

Calibration and validation of a dynamic model for water quality in combined sewer retention tanks

As the integrated management of urban wastewater systems becomes more and more popular, the development of wastewater management subsystem models appears essential to improve the understanding of the pollutant dynamics and their interactions. In such a context, a review of the literature reveals a lack of efficient models describing the dynamics of the water quality stored in off-line retention tanks. A model has thus been proposed based on the fractionation of suspended solids into three classes according to the particle settling velocity distribution measured in the field using the ViCAs settling test. In this paper, a calibration methodology is developed and full-scale field data sets from three different events are used for 1) calibrating this new dynamic retention tank model (two data sets); and 2) validating that model on the last data set. The results show a good agreement between observed and simulated data both for the total suspended solids and the total chemical oxygen demand.     

复掺纤维对RPC高温后力学性能及超声规律的影响

为了提高活性粉末混凝土(RPC)的力学性能并改善其高温爆裂性,在RPC中将0.3%、0.4%聚丙烯纤维(PP)和0、1%、2%、3%钢纤维(S)组合复掺,共设计8组试件,养护并模拟火灾试验,统计试件在高温(200、400、600℃)作用下的爆裂情况,研究复掺纤维对高温后RPC的抗折和抗压强度、强度损失率、折压比的影响,抗压强度、受火温度与超声波速的规律,确定两种纤维的最佳配合比。结果表明:掺入PP可以改善RPC高温爆裂;RPC抗折、抗压强度、折压比及超声波速随受火温度升高均呈先上升再下降的趋势,复掺入S可提升RPC的抗压、抗折强度和折压比;当S与PP掺量分别为1%与0.3%、2%、0.4%时,RPC未爆裂且强度较高,超声波速与抗压强度的相关性也较高。     

New developments in predicting stage–discharge curves, velocity and boundary shear stress distributions in open channel flow

The stage–discharge curve, depth-averaged velocity and boundary shear stress distributions are required to be determined for flood alleviation schemes. These parameters are hard to predict because of the three-dimensional (3-D) aspects of flow in open channels. This paper proposes a new approach for modelling open channel flow based on the Shiono and Knight Method (SKM), which is a depth-averaged model based on the governing Navier–Stokes equations. The modelling philosophy is applied to natural rivers and artificial channels both in inbank and overbank flow conditions. Accurate results are obtained when compared with field data and experimental measurements. Modelling philosophies are presented for the three calibration coefficients of the SKM. These coefficients represent the most important features of the 3-D flow mechanism.