关于热风式横流圆筒烘干机几个问题的讨论

提出了热风式横流圆筒烘干机在附属设备及生产工艺上存在的几个主要问题关分析了产生的原因,为该机的设计制造,推广使用技术改造提供一定有益的帮助。     

Soil moisture estimation over vegetated terrains using multitemporal remote sensing data

A new method for retrieving soil moisture content over vegetated fields, employing multitemporal radar and optical images, is presented. It is based on the integration of the temporal series of radar data within an inversion scheme and on the correction of the vegetation effects. The retrieval algorithm uses the Bayesian maximum posterior probability and assumes the existence of a relation among the soil conditions at the different times of the series. The correction of the vegetation effects models the variation, with respect to the initial time of the series, of the component of the backscattering coefficient due to the soil characteristics as function of the variations of the measured backscattering coefficient and of the biomass. The method is tested on the data acquired throughout the SMEX02 experiment. The results show that measured and estimated soil moistures are fairly well correlated and that the performances of multitemporal retrieval algorithm are better than those obtained by employing one radar acquisition, especially in terms of capability to detect soil moisture changes. Although the approach to correct the vegetation effects on radar observations needs to be further assessed on different sets of data, this finding demonstrates that the proposed method has a potential to improve the quality of the soil moisture retrievals.     

An improved algorithm for disaggregating microwave-derived soil moisture based on red, near-infrared and thermal-infrared data

Accurate high-resolution soil moisture data are needed for a range of agricultural and hydrologic activities. To improve the spatial resolution of ∼ 40 km resolution passive microwave-derived soil moisture, a methodology based on 1 km resolution MODIS (MODerate resolution Imaging Spectroradiometer) red, near-infrared and thermal-infrared data has been implemented at 4 km resolution. The three components of that method are (i) fractional vegetation cover, (ii) soil evaporative efficiency (defined as the ratio of actual to potential evaporation) and (iii) a downscaling relationship. In this paper, 36 different disaggregation algorithms are built from 3 fractional vegetation cover formulations, 3 soil evaporative efficiency models, and 4 downscaling relationships. All algorithms differ with regard to the representation of the nonlinear relationship between microwave-derived soil moisture and optical-derived soil evaporative efficiency. Airborne L-band data collected over an Australian agricultural area are used to both generate ∼ 40 km resolution microwave pixels and verify disaggregation results at 4 km resolution. Among the 36 disaggregation algorithms, one is identified as being more robust (insensitive to soil, vegetation and atmospheric variables) than the others with a mean slope between MODIS-disaggregated and L-band derived soil moisture of 0.94. The robustness of that algorithm is notably assessed by comparing the disaggregation results obtained using composited (averaged) Terra and Aqua MODIS data, and using data from Terra and Aqua separately. The error on disaggregated soil moisture is systematically reduced by compositing daily Terra and Aqua data with an error of 0.012 vol./vol.     

A sequential model for disaggregating near-surface soil moisture observations using multi-resolution thermal sensors

A sequential model is developed to disaggregate microwave-derived soil moisture from 40 km to 4 km resolution using MODIS (Moderate Imaging Spectroradiometer) data and subsequently from 4 km to 500 m resolution using ASTER (Advanced Scanning Thermal Emission and Reflection Radiometer) data. The 1 km resolution airborne data collected during the three-week National Airborne Field Experiment 2006 (NAFE'06) are used to simulate the 40 km pixels, and a thermal-based disaggregation algorithm is applied using 1 km resolution MODIS and 100 m resolution ASTER data. The downscaled soil moisture data are subsequently evaluated using a combination of airborne and in situ soil moisture measurements. A key step in the procedure is to identify an optimal downscaling resolution in terms of disaggregation accuracy and sub-pixel soil moisture variability. Very consistent optimal downscaling resolutions are obtained for MODIS aboard Terra, MODIS aboard Aqua and ASTER, which are 4 to 5 times the thermal sensor resolution. The root mean square error between the 500 m resolution sequentially disaggregated and ground-measured soil moisture is 0.062 vol./vol. with a bias of − 0.045 vol./vol. and values ranging from 0.08 to 0.40 vol./vol.     

Effects of soil moisture and water depth on ERS SAR backscatter measurements from an Alaskan wetland complex

We conducted a preliminary investigation of the response of ERS C-band SAR backscatter to variations in soil moisture and surface inundation in wetlands of interior Alaska. Data were collected from 5 wetlands over a three-week period in 2007. Results showed a positive correlation between backscatter and soil moisture in sites dominated by herbaceous vegetation cover (r = 0.74, p < 0.04). ERS SAR backscatter was negatively correlated to water depth in all open (non-forested) wetlands when water table levels were more than 6 cm above the wetland surface (r = − 0.82, p < 0.001). There was no relationship between backscatter and soil moisture in the forested (black spruce-dominated) wetland site. Our preliminary results show that ERS SAR data can be used to monitor variations in hydrologic conditions in high northern latitude wetlands (including peatlands), particularly sites with sparse tree cover.     

汽水分离器的动态数学模型和仿真研究

对汽水分离器的基本结构和原理进行分析,建立了热力系统的动态数学模型。并进行了仿真研究。与实验数据比较本模型具有一定的精度。并在软件的实现上具有一定的创新性。在模块化建模和状态空间在热力系统的仿真上具有一定的通用性价值。     

一种检测绝缘纸板微水分的电容式传感器

开发一种用于检测变压器绝缘纸板微水分的电容式传感器 ,该传感器通过感应绝缘纸板的介电常数在其干燥过程中的变化而用于在线实时检测。它灵敏度高、温度漂移小、便于安装和信号传送 ,其输出信号经处理后 ,可由微机处理并显示水的质数分数。介绍了传感器的工作原理、结构形式及相关系统。     

间苯二甲腈水分测定方法

介绍了以三氯甲烷配制间苯二甲腈样品溶液，利用微量水分仪测定样品中水分的原理、操作方法和对方法的讨论。     

真空油炸胡萝卜脆片等温吸湿规律的研究

重点研究了脆片在水分活度为0．06-0．95。温度分别为10℃、25℃、40℃条件下的吸湿平衡含水率变化规律。根据目前在农产品吸湿规律研究中常用的六种模型对三个温度条件下胡萝卜脆片的吸湿试验点进行了模拟比较。以模型的确定系数、标准误差以及平均相对预测误差作为评价指标，得出了Peleg、Halsey以及GAB模型，可以较好地预测胡萝卜脆片在不同温度条件下的吸湿规律，并确定了它们的模型系数。     

Mechanism and control of water seepage of vertical feeding borehole for solid materials in backfilling coal mining

To solve the problem of water seepage of vertical feeding borehole for solid materials, we established the fluid-solid coupling dynamic model of groundwater flowing in rock mass adjacent to the vertical feeding borehole. Combining with the engineering geological conditions, we built a numeral model to study the influence rule of the aquifer hydraulic pressure and seepage location of feeding borehole on the amount of seepage with finite element numerical method. The results show that the nonlinear relationship is presented among the amount of seepage, the seepage location and aquifer hydraulic pressure. The higher the aquifer hydraulic pressure is, the closer the distance between seepage location and aquifer is, and the faster the harmful levels of aquifer will grow. In practice, we calculated the allowable seepage of feeding borehole by the optimum moisture content and natural moisture content of backfilling materials, and then determined the protection zone of feeding borehole, so the moisture content of backfilling materials can be controlled within the scope of optimum moisture content.