岸滩侧蚀崩塌速率的试验量测方法

岸滩侧蚀崩塌现象普遍存在于冲积河流演变过程中,是河道治理需重点关注的问题之一,岸滩侧蚀崩塌速率的准确量测则是崩岸机理及其治理措施研究的关键基础。基于图像处理技术,建立了河岸侧蚀崩塌速率试验量测系统,通过图像追踪河岸模型上边缘示踪网格位置变迁,提出了一种河岸侧蚀崩塌速率测量方法。以试验水槽为例,对河岸侧蚀崩塌速率进行了量测,并与经验公式计算值进行了比对,两者基本吻合,可较好地反映流速、土体级配等岸滩侧蚀崩塌速率的影响因素及其变化规律。研究成果可为江河崩岸机理的深入研究提供技术支撑。

土木工程结构试验量测技术研究进展与现状

作为结构工程学科三级构成当中的一部门,结构试验是第一性的。其任务主要是在试验对象或结构物上作用荷载、温度、地震等因素,通过对于试件和结构工作项目相关的参数进行量测,进而对其具体的工作性进行综合判断,将结构承载能力估算出来,为后期工程设计中提高结构可靠性、安全性以及优化结构提供参考依据。

非饱和土基质吸力量测试验研究与探讨

土-水特征曲线能够解释非饱和土力学的许多力学特性。土-水特征曲线的获取依赖于试验设备、试验技术、试验方法,土-水特征曲线的准确获取能够促进非饱和土力学的发展。结合目前的非饱和土力学研究,对现有主要非饱和基质吸力量测试验进行了归纳总结。

农业高校专业认证视角下本科生专业课程创新探索——以“水工试验与量测技术”课程为例

工程教育专业认证是我国推进高等工程教育改革、构建工程教育质量体系、提高工程教育国际认可度的有效途径。本文基于专业实践类课程在教学过程中存在的问题,阐述了新工科背景下以专业认证为导向的工科教学改革实践的落实方案与可行性。以水工试验与量测技术课程中“文丘里量测装备”这一知识点为例,从教学目标、教学方法、教学思想、教学科研四方面探讨新型教学模式实施过程及保障途径。

北山坑探设施开挖全过程围岩内部位移现场量测试验研究

为研究硬岩条件下巷道开挖围岩内部位移变化特征,以高放废物地质处置地下实验室北山坑探设施为试验平台,设计原位试验方案,开展围岩内部位移现场量测试验,分析巷道开挖全过程围岩内部位移的演化特征,采用Lee方程、Hoek方程、V-D方程3个典型LDP曲线方程进行掌子面空间效应分析和损失位移求取。研究结果表明:北山花岗岩地质条件下,巷道爆破开挖全过程中,围岩内部位移变化随掌子面的推进呈现初始增长、快速增长和稳定收敛3个阶段;量测断面附近的围岩内部位移时态曲线呈现出阶跃特征,与分级加载下岩石蠕变试验曲线的形态特征相类似;距离巷道侧壁较远的测点受掌子面空间效应的影响范围较小,且在掌子面前方产生的位移释放量所占比重较大;采用Hoek方程求解的损失位移与实测值更为接近,为最优求解方程;在距掌子面2 m远设置量测断面,其损失位移已占总位移的50%以上。研究结果可为后续地下实验室开挖过程中的围岩内部位移量测和分析提供借鉴与参考。

考虑广义边界条件的混凝土应变软化

混凝土试验结果往往具有很大离散性,造成这种离散性的原因不仅是"材料的离散性"也存在"边界条件的离散性"。除试件与试验机加载板和试件接触面(即所谓的"狭义边界条件")以外,试验机刚度、试件尺寸和加载方式均系统地影响试验结果,特别在量测混凝土的应变软化方面,这个问题不可忽视。目前这些问题如果不能得到澄清,将严重影响对混凝土真实力学性质的认识。根据通常的实验室条件定义了一种"广义边界条件",以量测比较困难的混凝土单轴拉伸应变软化试验为例,来探索这种"广义边界条件"的影响。为此,建立了一个新的系统模型,将试验机与试件置于同一个系统中考虑,利用能量原理得出量测的稳定条件,并利用系统的平衡协调关系定量求出了应变软化条件下的稳定平衡路径。最后,通过在实验室完成的一组混凝土单轴拉伸试验验证了这个系统模型的合理性。同样的做法可以推广到其他更容易量测的混凝土加荷试验中,这将有助于正确认识混凝土试验结果的离散性。

Estimation of Biological Nitrogen Fixation Capacity by Sugarcane Using 15N

[ Objective] The study aimed to reveal the biological nitrogen fixation capacity by sugarcane from Brazil under the ecological conditions of Guangxi, and to provide reference for study on the biological nitrogen fixation capacity by sugarcane and related generalization and application. [ Method] The ^15N isotopic fertilizer was solely applied on plants of three sugarcane cultivars planted in greenhouse with no other fertilizer forms applied, meanwhile virus-free stem seedling was regarded as control, to measure their biological nitrogen fixation capacity using ^15N isotope. [ Result ] The nitrogen fixation rate of B8 from Brazil reached 26.91%, while Guitang 11 and RIC16 presented no or poor nitrogen fixation capacity. [ Conclusion] The sugarcane eultivar B8 from Brazil showed some nitrogen fixation capacity under the ecological conditions of Guangxi.

DEVELOPMENT FOR HIGH PRECISION SIX COMPONENT STRAIN GAUGE BALANCE

The measurement accuracy of a wind tunnel balance is the key factor to improve the measurement accuracy for a test model in the wind tunnel. In order to improve the measurement accuracy of the wind tunnel balance, a great deal of investigation is carried out in China. This paper summarizes a program to improve the measurement accuracy of wind tunnel balances. In the program, the investigation is carried out in three aspects (1) designing a drag component of the balance in low interactions (2) choosing high quality foil strain gauges with temperature self-compensation (3) choosing the excellent gauges and mounting them meticulously. As an example, these research achievements are applied in a φ18 six component balance. The measurement accuracy of a GB-04 standard model in a transonic wind tunnel with the φ18 six component balance comes up to the advanced world standard.

An NT-MT Combined Method for Gross Error Detection and Data Reconciliation

An NT-MT combined method based on nodal test (NT) and measurement test (MT) is developed for gross error detection and data reconciliation for industrial application. The NT-MT combined method makes use of both NT and MT tests and this combination helps to overcome the defects in the respective methods. It also avoids any artificial manipulation and eliminates the huge combinatorial problem that is created in the combined method based on the nodal test in the case of more than one gross error for a large process system. Serial compensation strategy is also used to avoid the decrease of the coefficient matrix rank during the computation of the proposed method. Simulation results show that the proposed method is very effective and possesses good performance.

MEASUREMENT OF REGIONAL BONE BLOOD FLOW IN THE CANINE MANDIBULAR RAMUS USING RADIOLABELLED TOAD RED BLOOD CELLS

Toad red blood cells were used to measure regional bone blood flow in the canine mandibular ramus. The blood cells were labelled with sodium pertechnetate and fixed in 1 0%formalin; they were 22 × 15 μm in size and had a specific gravity close to that of dog red blood cells. These cells had no discernible effect on systemic hemodynamics after injection, did not agglutinate, were well mixed and evenly distributed throughout the body, and were completely extracted in one circulation through the mandible. The mandibular ramus was divided into six regions. and the blood flow rates in each were found to be similar to those reported in previous studies with radiolabelled carbonized, microspheres. Furthermore, the blood flow distribution pattern of the mandibular ramus determined in this study was identical to that of our previous study using the bone-seeking radionuclide method. We suggest that radiolabelled toad red blood cells are an ideal marker for measuring regional blood flow in the canine mandible.

Experimental study on the effects of big particles physical characteristics on the hydraulic transport inside a horizontal pipe

This paper presents an experimental study of the physical characteristic effects of large particles on hydraulic transport in a horizontal pipe.The particles are spherical and are large with respect to the diameter of the pipe(8%,10%,16% and 25%).Experiments were done to test the important parameters in solid transport(pressure,velocity,etc.).As a result,the relationship between the pressure gradient forces and the mixture velocity was substantially different from the pure liquid flow.However,in a single-phase flow a monotonous behavior of the pressure drop curve is observed,and the curve of the solid particle flow attains its minimum at the critical velocity.The regimes are characterized with differential pressure measurements and visualizations.

Designing similarity measurement with distance measure and application on laterally directional mode flight test

Similarity measure construction has been proposed as fault detection of flight test method in order to obtain the primary control surface stuck and the combination stuck of primary control.Similarity measures were obtained through analyzing the certainty and uncertainty of fuzzy membership functions,which were designed based on well-known Hamming distance.It was applied to the fault detection of primary control surface stuck of uninhabited aerial vehicle(UAV).At post-failure control surface,if the UAV is controllable and trimmable using other control surfaces,the UAV is able to fly or return to the safety region through reconfiguration of flight control system.To detect the fault,similarity measure computations were carried out.This result could be applicable with the real-time parameter estimation method.By monitoring the value of coefficients due to the control surface deviation,it becomes aware that the control surface fault occurs or not.The control surface stuck position and value were separated by comparing the trim value with the reference value.This is the advantage of increasing in reliability without adding sensors or with additional low cost.

Modification of B3 Model for Sealed Concrete with Additives Based on Experimental Observations

Thirteen specimens were tested out of which nine were for creep of sealed concrete and four for shrinkage test,for a period of 700 d under controlled temperature condition.The experimental results for creep and shrinkage were compared with creep and shrinkage computation model B3 and distinct discrepancies between observed and calculated creep and shrinkage strains were observed.Based on regression analysis,modification on B3 model has been formulated which will be applicable at least for concrete of characteristics strength of C40 and C50 with additives.Besides,on the basis of observation on identical specimens with varied stress strength ratio,a function is generated which accounts effect of stress strength ratio on creep.Finally,Civil Engineering community is suggested not to follow the creep prediction models without correction at least for modern concrete,as they do not account the effect of additives on its compliance function.

Dynamic error research and application of an angular measuring system belonging to a high precision excursion test turntable

Angular measuring system is the most important component of a servo turntable in inertial test apparatus. Its function and precision determine the turntable＇ s function and precision. It attaches importance to research on inertial test equipment. This paper introduces the principle of the angular measuring system using amplitude discrimination mode. The dynamic errors axe analyzed from the aspects of inductosyn, amplitude and function error of double-phase voltage and wavefonn distortion. Through detailed calculation, theory is provided for practical application; system errors are allocated and the angular measuring system meets the accuracy requirement. As a result, the schedule of the angular measuring system can be used in practice.

The Application of a Smartphone in Ship Stability Experiment

The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in the measurement of heel angle. Nowadays, digital inclinometers are available, but they are expensive. In this study, the use of a smartphone application is presented for ship inclination and rolling-period tests. The idea consists of using accelerometer and gyroscope sensors built into the current smartphones for the measurements. Therefore, some experiments are carried out on an example trawler model to exhibit the uses and advantages of this method. The obtained results are in good agreement with those provided from the pendulum method and natural roll-period test. This application is new, easy, and more accurately assesses metacentric height during the inclining and rolling-period tests.

Accurate vision measurement for kinematic parameters of satellite separation tests

The accurate measurement of kinematic parameters in satellite separation tests has great significance in evaluating separation performance. A novel study is made on the measuring accuracy of monocular and binocular, which are the two main vision measurement methods used for kinematic parameters. As satellite separation process is transient and high-dynamic, it will bring more extraction errors to the binocular. Based on the design approach of intersection measure and variance ratio, the monocular method reflects higher precision, simpler structure and easier calibration for level satellite separation. In ground separation tests, a high-speed monocular system is developed to gain and analyze twelve kinematic parameters of a small satellite. Research shows that this monocular method can be widely applied for its high precision, with position accuracy of 0.5 mm, speed accuracy of 5 mm/s, and angular velocity accuracy of 1 (°)/s.

A Simple Bioassay Using Fluorescent Microbeads and Daphnia magna

The amount of microbeads ingested by Daphnia magna decreases on exposure to toxic materials; tins oenawor was used to develop a toxicity test. To determine the toxicity of seven metals, D. magna were collected and homogenized, and the fluorescence intensity of the microbeads ingested by D. magna was measured. The amount of ingestion was determined from fluorescence intensity. The fluorescence intensity was half of that of the controls which was measured as the 30 min-FI50, and these data correlated well with those from an acute immobilization method （24 h-EC50）. An advantage of the method using fluorescent beads is that an estimate of the 24 h-EC50 can be obtained.

MEMS Test System Based on Virtual Instrument Technology

On account of the multiformity of MEMS devices, it is necessary to integrate with some optical measurement techniques for meeting static and dynamic unit test requirements. In this paper, an automated MEMS test system is built of some commercially available components and instruments based on virtual instrument technology. The system is integrated with stroboscopic imaging, computer micro-vision, microscopic Mirau phase shifting interferometry, and laser Doppler vibrometer, and is used for the measurement of full-view in-plane and out-of-plane geometric parameters and periodical motions and single spot out-of-plane transient motion. The system configuration and measurement methods are analyzed, and some applications of the measurement of in-plane and out-of-plane dimensions and motions were described. The measurement accuracy of in-plane dimensions and out-of-plane dimensional is better than 0.2 um and 5 nm respectively. The resolution of measuring in-plane and out-of-plane motions is better than 15 nm and 2 nm respectively.

Study on Test Methods for Flow Ability of Superfine Powder Extinguishing Agent

According to the physical and chemical characteristics of superfine powder extinguishing agent,three test methods are selected to measure the flow ability.By studying and comparing various test methods,apparatus and conditions,the optimum method and conditions to test flow property of superfine powder extinguishing agent are confirmed.

A Refined Formula for the Allowable Soil Pressure Using Shear Wave Velocities

Based on a variety of case histories of site investigations, including extensive bore hole data, laboratory testing and geophysical prospecting at more than 550 construction sites, an empirical formulation is proposed for the rapid determination of allowable bearing pressure of shallow foundations in soils and rocks. The proposed expression corroborates consistently with the results of the classical theory and is proven to be rapid, and reliable. Plate load tests have been also carried out at three different sites, in order to further confirm the validity of the proposed method. It consists of only two soil parameters, namely, the in situ measured shear wave velocity and the unit weight. The unit weight may be also determined with sufficient accuracy, by means of other empirical expressions proposed, using P or S -- wave velocities. It is indicated that once the shear and P-wave velocities are measured in situ by an appropriate geophysical survey, the allowable bearing pressure as well as the coefficient of subgrade reaction and many other elasticity parameters may be determined rapidly and reliably.