Farmers' preferences for adopting on-farm concentration of raw milk: Results from a discrete choice experiment in Germany

Milk concentrates are used in the manufacturing of dairy products such as yogurt and cheese or are processed into milk powder. Processes for the nonthermal separation of water and valuable milk ingredients are becoming increasingly widespread at farm level. The technical barriers to using farm-manufactured milk concentrate in dairies are minimal, hence the suspicion that the practice of on-farm raw milk concentration is still fairly uncommon for economic reasons. This study, therefore, set out to investigate farmers' potential willingness to adopt a raw milk concentration plant. The empirical analysis was based on discrete choice experiments with 75 German dairy farmers to identify preferences and the possible adoption of on-farm raw milk concentration. The results showed that, in particular, farmers who deemed the current milk price to be insufficient viewed on-farm concentration using membrane technology as an option for diversifying their milk sales. We found no indication that adoption would be impeded by a lack of trustworthy information on milk processing technologies or capital.     

Flow distribution and mass removal in floating treatment wetlands arranged in series and spanning the channel width

Floating treatment wetlands (FTWs) use plants’ roots for water quality improvement. The plants are supported by a buoyant structure deployed at the water surface. The roots form a porous zone beneath the structure and remove pollutants carried in suspension through filtering, absorption and uptake. This paper used CFD simulation to model FTWs arranged in series and spanning the channel width and to study the effects of root length and spacing between FTWs on flow distribution and mass removal. The root zone was modelled as a porous media, and removal was computed using first-order decay, for which a range of removal constants was tested. Longer roots increased the reactive volume of the root zone, which increased the fraction of pollutant inflow entering the FTWs. Increasing the distance between FTWs allowed greater mixing between water that went through and beneath the upstream FTW. This increased the concentration entering each FTW, which enhanced mass removal per FTW. However, a larger distance between FTWs reduced the number of FTWs in the channel, reducing the reactive volume. In the tradeoff between mixing and reactive volume, the reactive volume was more important, such that total removal in the channel increased with longer roots and more units of FTW (shorter gap distance). However, removing the gap entirely was detrimental, as FTWs in series removed more mass than a continuous FTW of same volume. This study points to two design recommendations for FTWs in series. First, if resources for building FTWs are not limiting, but the channel length is, it is preferable to prioritize higher reactive volume (shorter gap distance) to achieve maximum removal per channel length. Second, if resources for FTWs are limiting, but channel length is not, it is better to place the FTWs with a longer gap distance, preferably along enough to allow mixing over the full depth between FTWs, as this will achieve maximum removal per FTW.     

煤矿水仓清理新工艺

通过调研现场情况以及检测煤泥特性，探寻一种实用性强、方法简单的新工艺来替代劳累的人工和繁琐的机械清淤，解决现实问题。针对实际情况开发清仓新工艺，介绍了该工艺的技术路线选择、设计依据以及实际应用效果。该新工艺具有降低清仓时间、减轻工人劳动强度、设备操作简单、实用性强等特点。     

矿用履带式运输车在复杂开采条件下的应用

为了方便煤炭的运输，某矿使用了矿用履带式搬运车。履带运输车解决了轮式运输车在恶劣道路条件下不能行走的问题，这种履带车是一种新型的运输工具，其特点是体积小、转弯灵活、动力强大，可在不受场地限制的情况下轻松通过狭窄的地方，能有效解决山区、土壤、陡坡等恶劣条件下物料的运输问题，适合普通运输车辆无法通行的地方。介绍了矿用履带式搬运车的主要结构以及工作原理，并给出了实际应用中应注意的事项。     

Concentration dependence of physical properties of low temperature processed ZnO quantum dots thin films on polyethylene terephthalate as potential electron transport material for perovskite solar cell

Colloidal Zinc oxide quantum dots (ZnO QDs) prepared with varying concentrations through precipitation method were deposited on flexible ITO/PET substrates using spin-coating technique. Various characterization tools were utilized to investigate the morphological, structural, electrical and optical properties of the films. The crystallinity of the films was found to improve with increasing ZnO QD concentration (ZQ_C) as evident from the X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) studies. Crystallographic and optical parameters were evaluated and explained in depth. The average nanograin size and bandgap were increased and decreased respectively, from ～5 nm to ～8 nm and 3.29 eV–3.24 eV with an increase in ZQ_C from 10 mg/mL to 70 mg/mL. Columnar structure growth of the films is revealed by AFM results. The films showed decent optical transparency up to 81%. All the ZnO films exhibited n-type semiconducting property as indicated by the electrical measurements with carrier mobility and low resistivity of 12.21–26.63 cm²/Vs and 11.84 × 10^?3 to 13.16 × 10^?3 Ω cm respectively. Based on the experimental findings, ZnO QD nanostructure film grown at 50 mg/mL is envisaged to be a potential candidate for flexible perovskite photovoltaic application.     

低阶煤颗粒-气/油泡间的诱导时间研究

为表征低阶煤颗粒-气/油泡间矿化过程的差异,通过Sutherland理论下固体颗粒进入泡沫产品的总概率(E)和浮选速率常数(k)之间关系,并结合低阶煤颗粒-气/油泡的浮选速率试验,求得了低阶煤颗粒-气/油泡间的诱导时间。浮选实验研究表明,在相同的捕收剂消耗量下低阶煤-油泡浮选产率均高于低阶煤-气泡浮选产率。诱导时间测试表明,低阶煤颗粒-油泡间的诱导时间(35 ms)要明显低于低阶煤颗粒-气泡间的诱导时间(93 ms)。上述实验结果表明,油泡表面的疏水性要强于传统浮选气泡表面的疏水性。然而,进一步利用Sutherland理论中固体颗粒进入泡沫产品的总概率和浮选速率常数之间的数学关系,并结合低阶煤颗粒-气/油泡的浮选速率试验求得的低阶煤颗粒-气/油泡间的诱导时间分别为9.67和8.46 ms,其与诱导时间测试仪分别测量的诱导时间差异很大。这主要是由于在实际浮选过程中气/油泡的上升速度分别为23.26和22.68 cm/s,其远高于2015EZ型诱导时间仪测试过程中气/油泡碰撞速度(2.0 cm/s)。因此,诱导时间理论计算表明气泡-颗粒间的碰撞速度对颗粒-气泡间的诱导时间影响很大。上述研究结果表明油泡浮选效果优于传统浮选的内在原因在于低阶煤颗粒-油泡间的诱导时间小于低阶煤颗粒-气泡间的诱导时间。     

沁水盆地赵庄矿3号煤层地面煤层气抽采低产原因分析

在对沁水盆地赵庄矿煤层气开发地质、煤层气生产井资料深入研究的基础上，分析、总结了区内煤层气直井低产原因，并据此提出了区内地面抽采后续开发方向。研究认为:3号煤层气含量偏低、含气饱和度低、临储比低，致使排采阶段气含量可降幅度低，是其低产的宏观表征；3号煤储层不匹配孔级，较差连通性，即微、小孔为主，中孔次之，大孔不发育，微裂隙连通性差，致使扩散缓慢、影响储层改造和抽采效果，是其低产的微观表征；3号煤层远高于顶底板塑性及相近的水平应力，进一步造成改造缝长受限，泄流面积不足。因此，建议区内后续地面抽采方式应以增大泄流面积开发方式为主。     

放顶煤液压支架在土耳其IMABT煤矿现场的应用

通过对土耳其IMBAT煤矿地质条件的分析研究，结合多种选型计算方法的验证，最终选择了合适的设备，使该矿的开采效率得到较大提升。同时也扩大了我国的煤炭开采装备应用范围。根据在土耳其IMBAT煤矿现场多年的服务经验，将理论与实践相结合，就综采放顶煤液压支架在土耳其IMABT煤矿现场的应用进行了论述。     

提升管内颗粒浓度梯度力的特性

由于Kutta-Joukowski横向力与浓度梯度力的共同作用，提升管内颗粒沿径向在边壁大量聚集并形成稳定的环?核结构。根据实验数据，分析了颗粒浓度梯度的径向分布特征，考察了不同操作条件下浓度梯度力系数K的分布特性。由Kutta-Joukowski横向力与浓度梯度的关系，提出了浓度梯度力的表达式Fρ=K(dρ/dr)A及浓度梯度力系数K的表达式K=[?ρg(νg?νp)(?v/?r)r]/?dρ/dr+(d2ρ/dr2)r?。提升管内颗粒群受到的浓度梯度力与浓度梯度力系数K有关。浓度梯度力系数K在提升管中心处为0，沿提升管径向呈“N”型分布，随表观气速增加而增加；提升管内充分发展段K的数值明显大于提升管加速区和出口约束区，总结了浓度梯度力系数K的经验关联式。