月水量平衡模型在中国不同气候区的应用

概念性水文模型是目前评价环境变化对区域水文水资源影响的有力工具,大尺度水文模拟是气候变化影响评价中的关键技术.利用10个位于我国不同气候区的代表性流域的水文气象资料.验证了月水量平衡模型在不同气候区的应用效果.结果表明:月水量平衡模型能够适用于我国不同气候区的月流量过程模拟,其中,对湿润半湿润地区的模拟精度好于干旱半干旱地区的模拟效果;若流域内降水径流量关系密切,则水文模拟的效果也会较好.人类活动的影响,使得长序列水文模拟误差增大,但不同人类活动类型对流域水文模拟效果的影响是不同的.     

天生桥一级水电站施工总布置研究

天生桥一级水电站采用合同管理方式建设，主体工程划分为四个土建及金属结构安装合同和一个厂房永久机电设备安装工程合同，为满足合同管理的要求，进行了场内外交通运输设计、施工场地划分、公用施工临时设施和专用施工临时设施的划分、土石方平衡规划等设计工作，潢足了工程建设的需要     

基于全极化雷达数据反演夏玉米覆盖农田表层土壤含水量

基于RADARSAT-2全极化C波段雷达数据和野外实测数据,建立了不同极化方式的后向散射系数与夏玉米植被含水量的响应关系,获得了山东禹城夏玉米覆盖区域农作物含水量。在此基础上,对＂水—云模型＂的参数进行了修改,从总的极化雷达后向散射中去除了植被影响,获取了土壤组分的后向散射系数,从而能够通过雷达多极化数据得到表层土壤含水量。结果表明：夏玉米植被含水量观测值与VH、VV后向散射系数的相关性均达到显著水平,相关系数分别为0.86和0.79,VH极化优于VV极化;在RADARSAT-2四种极化方式下,VV极化下的＂水—云模型＂理论计算的误差平方和最小,是研究区表层土壤含水量反演的最优极化方式。     

汾河清水复流生态调水量研究

基于河道单元水量平衡原理,通过对汾河河道来水、供水的分析,计算不同规划水平年方案下汾河主要控制断面流量过程,确定了汾河复流的合理生态用水量。结果显示：现状年汾河河道生态基流除汾河二库以上河道之外,以下河道均不能得到完全满足。为此,河道生态环境状况比较严峻;河流生态方面考虑满足河道基流生态需水及河滨带生态中水平用水,在万家寨引黄3.2亿m3、沁河引水7 304万m3的情景下,基本可满足汾河生态保护与恢复的要求。     

N-甲基对硝基苯胺水分测定方法的改进

用卡尔-费休法测定N－甲基对硝基苯胺水分，改变传统测定方法中半自动滴定为自动滴定，反应溶液由N，N－二甲基甲酰胺／无水甲醇（体积比4：3），改为三氯甲烷／无水甲醇（体积比3：2），改善了溶液对电极灵敏度的影响，缩短了预滴定时间，提高了分析的准确度。     

75 mm stroke flexure stage for the LNE watt balance experiment

The LNE watt balance experiment aims at measuring the ratio of the Planck constant h to a standard mass m with a relative uncertainty smaller than 10⁻⁸. One step of our experiment requires to move a coil vertically inside a magnetic field along a total stroke of about 75 mm. To limit the uncertainty of our experiment, the velocity of the coil is servo-controlled at a constant value of 2 mm/s and the deviations of the trajectory from a rectilinear translation must be kept within 1 μm for straightness and within 5 μrad for yaw and pitch. These requirements must be performed along a useful stroke of 40 mm.To avoid play and friction, which are likely to perturb the feedback loop of the coil velocity, a flexure stage has been built to constrain the movement of the coil. For a 40 mm stroke, measurements show that the two straightness errors are smaller than 0.2 μm and 0.5 μm respectively, and that pitch and yaw are smaller than 4 μrad and 6 μrad respectively.     

Antimicrobial efficacy of cinnamon oil against Salmonella in almond based matrices

Reduced moisture enhances resistance of Salmonella and subsequently reduces the antimicrobial efficacy of thermal treatment. Alternative and supplementary non-thermal intervention methods are urgently needed. In this study, Cinnamonum cassia oil was tested for its antimicrobial effect against outbreak strains Salmonella Enteritidis PT30 and S. Tennessee K4643. Minimal inhibitory concentration and minimal bactericidal concentration for both strains were 0.05% (v/v) and 0.1% (v/v), respectively. Death curves showed that including 0.1% and 0.15% (v/v) C. cassia oil resulted in ∼7 Log reduction of bacteria within 2 h and 1 h, respectively. However, the antimicrobial efficacy of C. cassia oil was reduced when S. Enteritidis PT30 existed in low moisture condition. When S. Enteritidis PT30 was established on almonds/paper discs, 0.4% C. cassia oil resulted in ∼1.7 Log₁₀ CFU/almond or 3.2 Log₁₀ CFU/disc reduction within 2 h at room temperature, respectively. S. Enteritidis PT30 established on both almonds and paper discs were very stable, there was only a 0.80 Log₁₀ CFU/almond and 1.20 Log₁₀ CFU/disc reduction during 9-week and 7-week storage at room temperature, respectively. C. cassia oil intervention increased S. Enteritidis PT30 reduction on both almonds and paper discs during storage with more reduction on paper discs. 0.4% C. cassia oil treatment reduced S. Enteritidis PT30 on paper disc to undetectable level within 4 weeks, but only led to 2 Log₁₀ CFU reduction on almonds, indicating a protection effect from the almond matrix or almond surface components. Additionally, S. Enteritidis PT30 established on paper disc coated with almond surface components exhibited higher resistance to desiccation and C. cassia oil treatment, further demonstrating the protection role of food matrix. In conclusion, C. cassia oil is effective against S. Enteritidis PT30 and S. Tennessee K4643, but its antimicrobial efficacy against the tested Salmonella was compromised by low moisture environment and food matrix.     

Equilibrium moisture content and heat of desorption of saffron

The equilibrium moisture contents of saffron (Crocus sativus L.) stigmas were determined experimentally using the standard gravimetric method at temperatures 30, 45 and 60 °C and water activity ranging from 11% to 83%. The sorption isotherm curves of saffron were sigmoidal in shape and decreased with increased temperature at constant relative humidity. Five selected isotherm models GAB, modified Henderson, modified Chung‐Pfost, modified Halsaey and modified Oswin were tested to fit the experimental isotherm data. Modified Oswin and modified Henderson models were found acceptable for predicting desorption moisture isotherms and fitting to the experimental data, respectively. The isosteric heats of desorption, determined from equilibrium data using the Clausius‐Clapeyron equation, were found to be a function of moisture content. The net isosteric heat of desorption of saffron varied between 1.38 and 5.38 kJ mol^?1 at moisture content varying between 2% and 20% (d.b).     

A mathematical model for simulating heat and moisture transfer within porous cotton fabric drying inside the domestic air-vented drum dryer

A mathematical model was developed to describe the processes of coupled heat and mass and momentum transfer occurring in convective drying of 100% porous cotton fabric. In this model, the variation in both air and fabric properties were expressed as a function of temperature and moisture content. The resulting systems of transient non-linear partial differential equations in the space-time domain together with the set of initial values and boundary conditions were numerically solved by utilizing the finite difference method. A series of laboratory drying experiments were performed using a computer-controlled dehydration system, which was developed to obtain data of drying kinetics under varying operating conditions for the validation of the predicted results from the proposed model. The experimental results has shown a very good agreement with the predictions of the model, which indicates that the proposed numerical model can be used with confidence as a tool in optimizing the design and operation of the fabric drying system. A parametric study was performed using the modeling tool has demonstrated the impact of key operational parameters on the drying kinetics, which has significant meaning on improving fabric’s appearance smoothness and decreasing the damage. It is expected that the model can be applied for other fiber products and processes involving similar phenomena.     

平衡吊切向和径向操作力的控制

为减小平衡吊工作中切向和径向操作力,降低工人的劳动强度,同时提高生产效率,通过在生产加工平衡吊的过程中对其进行优化改进,并精准的实施装配工艺以及完善试车过程,就可以取得良好的效果。