填筑土体压实度快速检测试验

针对平原水库围坝填筑压实度快速检测做了大量的"三点击实"和标准击实试验。分析了三点击实试验过程中减水情况及加、减水情况下试验方法的可行性及其数据合理性,和标准击实试验方法进行了比较,认为减水情况及加、减水情况下试验方法是可行的,在减水情况下最优含水率和填土含水率的差值一般在-3%～0,同时试验过程中土体减水率小于6%时,三点击实试验成果比较合理。用三点击实试验方法填筑土体压实度所用时间比标准击实试验的方法省6～8h,三点击实试验填筑土体压实度的方法针对土体特性差别较大的工程中适用性强。提出了减水情况下的三点击实试验步骤及试验过程中的注意事项。     

非接触式物料水分传感器

为实现固体物料水分含量的在线监测,设计了基于频域反射原理的非接触式物料水分传感器。该传感器基于固体状物料含水量与介电常数的关系,利用电容式探头对介电常数的测量能力,通过水分变化关系实验建立了容积含水量与介电常数的数学模型,并完成了传感器的结构设计和电路设计。实验结果表明:该传感器实现了对固体颗粒状物料水分的准确测量,满足物料水分测量的实际需求。     

利用归一化微波差异指数和表面散射模型反演裸露地表土壤水分

在给定土壤质地和粗糙度状况条件下,用AIEM模型模拟AMSR-E的6.925GHz、10.65GHz和18.7GHz频率下不同含水量时土壤表面发射率和土壤温度的关系,分析表明V极化的发射率受土壤温度的影响很小,其变化主要由土壤水分的变化引起。通过计算不同频率组合V极化通道的归一化微波差异指数,并模拟与土壤水分的关系,然后利用这一关系对塔克拉玛干沙漠中部某地的土壤水分进行反演。结果发现用18.7GHz和10.65GHz V极化通道组合的反演值与AMSR-E Level 3土壤水分产品的吻合程度最好。在此基础上分别用3种常见的半经验表面散射模型:Q/H模型、Hp模型和Qp模型,通过计算上述通道组合的NMDI来反演研究区的土壤水分,结果表明利用3种半经验模型得到的反演值之间差异非常小,并且与用AIEM模型计算NMDI时的反演结果吻合较好。     

Thermophysical Analysis of Sandstone by Pulse Transient Method

Stones belong to porous materials where water in pores plays an important role during the freeze–thaw process. A thermophysical analysis based on the pulse transient method has been used to study an ageing cycle, namely the freeze–thaw cycle. Thermophysical analysis is based on measuring the thermophysical properties under specific thermodynamic conditions. The transient method determines the specific heat, thermal diffusivity, and thermal conductivity by a single measurement. A specimen of Sander sandstone was analyzed in both dry and water-saturated states. Typical anomalies of all thermophysical parameters at the freeze–thaw point as well as differences for the dry and saturated states were found. The changes of thermophysical parameters measured when using freeze–thaw cycles correspond to stone ageing. The freeze–thaw cycle can often be encountered in building physics, concrete construction, etcPaper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

微波法测定氧化钼块中钼和水分含量

将氧化钼样品经处理转化为钼酸铅沉淀后，以微波炉代替马弗炉对沉淀进行了干燥试验，同时对氧化钼的水分测定也采用了微波干燥法。结果表明，利用微波法可使沉淀干燥的时间由30min缩短为7min，氧化钼干燥时间由2h缩短为4min。显著提高了样品中钼和水分的测定速度。     

微波法快速测定钼酸铵中的水分

采用微波加热法对钼酸铵水分含量进行了测定。探讨了加热时间、微波功率和物料重量对水分测定的影响，并和传统烘箱测定进行了对比。     

一种基于有源电桥的电容式粮食水分传感器

在传统电桥电路的基础上,设计了一种有源电桥的电容式检测电路。该电路具有灵敏度高、线性范围宽的特点。将其用于粮食水分的检测,实现了一种具有线性特性的粮食水分传感器。通过试验测试粮食的电阻抗特性,尤其是电容特性与粮食水分之间的关系,确定了电路的工作频率。试验结果表明:这种粮食水分传感器的输出电压与粮食水分之间呈良好的线性关系,可满足粮食水分在线检测的要求。     

造纸过程水分智能控制

针对造纸过程的复杂性、工艺特点及要求，本文对造纸过程的水分控制，提出模糊控制和专家系统结合的智能控制方法。实践证明该控制器满足了造纸过程对水分的工艺要求，且具有良好的鲁棒性。     

Soil moisture estimates from TRMM Microwave Imager observations over the Southern United States

The lack of continuous soil moisture fields at large spatial scales, based on observations, has hampered hydrologists from understanding its role in weather and climate. The most readily available observations from which a surface wetness state could be derived is the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) observations at 10.65 GHz. This paper describes the first attempt to map daily soil moisture from space over an extended period of time. Methods to adjust for diurnal changes associated with this temporal variability and how to mosaic these orbits are presented. The algorithm for deriving soil moisture and temperature from TMI observations is based on a physical model of microwave emission from a layered soil-vegetation-atmosphere medium. An iterative, least-squares minimization method, which uses dual polarization observations at 10.65 GHz, is employed in the retrieval algorithm. Soil moisture estimates were compared with ground measurements over the U.S. Southern Great Plains (SGP) in Oklahoma and the Little River Watershed, Georgia. The soil moisture experiment in Oklahoma was conducted in July 1999 and Little River in June 2000. During both the experiments, the region was dry at the onset of the experiment, and experienced moderate rainfall during the course of the experiment. The regions experienced a quick dry-down before the end of the experiment. The estimated soil moisture compared well with the ground observations for these experiments (standard error of 2.5%). The TMI-estimated soil moisture during 6-22 July over Southern U.S. was analyzed and found to be consistent with the observed meteorological conditions.     

Monitoring Moisture Uptake and Delamination in CFRP-Reinforced Concrete Structures with Electrochemical Impedance Sensors

Electrochemical impedance spectroscopy (EIS) sensors have been used to inspect carbon fiber reinforced polymer (CFRP) -reinforced concrete structures exposed to a variety of test conditions. Similar specimens were also used to investigate the detection of delamination between the CFRP and the concrete using a modified wedge test configuration. The use of external electrodes attached to the CFRP surface, coupled with the embedded rebar, provided the best results. Equivalent circuit modeling was used to analyze the impedance spectra. Several circuit parameters, especially the capacitance and constant phase element (CPE) magnitude, correlated very well with both bonded area/delamination and moisture. Both parameters exhibit a linear relationship with delamination area. The capacitance also showed a linear relationship with moisture content while the CPE was more strongly dependent on moisture. Differences in the response of the specimens subjected to the different exposure conditions were seen and explained based on the moisture uptake of the various specimens.