Graduate Student Literature Review: Considerations for nutritional grouping in dairy farms

Each cow in a group has different nutritional requirements even if the group is formed by cows of similar age, number of lactations, and lactation stage. Common dairy farm management setup does not support formulating a diet that accurately matches individual nutritional requirements for each cow; therefore, a proportion of cows in the group will be overfed and another proportion underfed. Overfeeding and underfeeding cows increases the risk of metabolic diseases, decreases milk production, and increases nutrient waste. Consequently, profitability of dairy farms and the environment are negatively affected. Nutritional grouping is a management strategy that aims to allocate lactating cows homogeneously according to their nutritional requirements. Groups of cows with more uniform nutritional requirements facilitates the formulation of more accurate diets for the group. Current availability of large data streams on dairy farms facilitates the design of algorithms to implement nutritional grouping. Our review summarizes important factors to consider when grouping cows, describes nutritional grouping approaches, and summarizes benefits of implementing nutritional grouping in dairy farms.     

Long-term performance analysis of chemical filters in clean rooms based on a prediction model

Chemical filters are the most important devices for removing gas-phase pollutants in clean rooms. However, the testing concentration of chemical filters is too high for reflecting their performance in a real clean room environment. This study tested the adsorption performance of chemical filters in the two most commonly used shapes at different concentrations. Then, the Langmuir equation and Wheeler-Jonas kinetic equation were combined to establish an adsorption performance prediction model of chemical filters under actual conditions. The predicted values of the model were in good agreement with the experimental results, which indicated the high accuracy of the prediction model. The model does not need to test the microscopic parameters of the adsorbent and can maintain high accuracy at low concentrations. A fast method for calculating the service life of chemical filters was also presented. Based on this model, the total cost of using a chemical filter with a high carbon content in microelectronic clean rooms could be decreased by 45% due to decreasing the number of filter replacements over 3 months. So a chemical filter with a high carbon content should be preferred over a filter with low resistance in microelectronic clean rooms.     

迁钢210 t钢包全程加盖工艺及实践

迁钢二炼钢厂自投入使用210 t钢包全程加盖技术及工艺后，取得了显著效果，平均出钢温度降低10 ℃，钢包热周转使用率长期保持在85%以上，取消了钢包在线烘烤，降低了煤气消耗，有效地保证了钢包洁净度，提高了钢包包衬寿命。实践生产运行表明，炼钢生产中钢包全程加盖工艺是一项节能、环保、降耗的先进技术，为迁钢二炼钢厂取得了显著的经济效益。但在一段时间内，该工艺运行稳定性较差，通过现场生产数据归纳分析，从中找出了影响钢包加、揭盖的因素，并制定了控制措施；同时，岗位要掌握其操作要点及主要设备，才能提高运行稳定性。     

无烟煤制工业燃气项目原料煤价与经济性的关系分析

针对我国建材行业传统使用的常压固定床煤气发生炉及化肥行业固定床间歇气化炉面临淘汰,无烟煤市场萎缩的情况,提出以晋城无烟煤为原料,利用赛鼎碎煤加压气化技术,生产适合建材行业大规模使用的工业燃气。以无烟煤为原料的河北沙河年产26亿m^3工业清洁燃气项目为基础,对无烟煤与天然气价格、项目经济性的关系进行了分析,结果表明,以晋城无烟块煤运到河北沙河的到厂价935元/t计算,盈亏平衡天然气价约2.26元/m^3;以沙河工业天然气到户售价2.5元/m^3计算,盈亏平衡到厂煤价约1 077元/t,项目经济性较好。     

Innovations and productivity: the shift during the 2008 crisis

This paper investigates how the recent crisis of 2008 changed relations between innovation and firm performance in Western Europe. We apply a structural framework of CDM modelling, which incorporates different stages of the knowledge creation process and takes into account the complex nature of innovations. The study is based on a balanced panel data of 420 listed manufacturing firms from the U.K., Germany and France. All the information is gathered from common sources, thereby reducing subjectivity, a typical problem in the field. We found, the crisis resulted in appreciable changes in the model. The most important evidence is enhancement of the role of firm resources in the post-recession period. We also reveal larger barriers for innovations, increased uncertainty and lower state dependence in R&D engagement, product creation and economic performance. These results could indicate the ‘cleaning effect’ of the crisis, which has worsened the business environment and enhanced competition.     

端帮靠帮开采与搭桥内排相结合开采技术的应用

为了增加煤炭采出资源量和缩短内排土场运输距离,达到降低生产剥采比、提高经济效益和煤炭资源回收率的目的,根据河曲露天矿的开采条件,特提出端帮靠帮开采和工作帮与内排土场之间搭桥的开拓运输形式相结合的方法,主要研究不同搭桥高度产生的经济效益与靠帮开采产生的经济效益之和的对比,研究结果表明:在满足《露天矿设计规范》的前提下,靠帮开采将大幅提高经济效益,同时通过中间合适高度搭桥从技术上保证了运输系统的连贯性,验证了开采技术的有效性。     

太阳能吸收式制冷系统动态特性分析

以上海地区某太阳能集热器驱动的单效溴化锂吸收式制冷系统为对象,对各主要部件负荷在典型日随时间变化的动态特性进行研究。结果表明:随着制冷能力的增加,发生器、冷凝器、吸收器及集热器面积需求量均增加;当制冷能力一定时,发生器与吸收器的负荷呈现先增加后减小的趋势,而集热器面积需求量的变化则与之相反。经济性分析可知结果表明,集热器费用为910、1040和1170$/m^2时,系统投资回收期分别为8.2、9.5及10.8 a,具有良好的社会效益和经济效益。     

Thermodynamic and economic analyses of a coal and biomass indirect coupling power generation system

The coal and biomass coupling power generation technology is considered as a promising technology for energy conservation and emission reduction. In this paper, a novel coal and biomass indirect coupling system is proposed based on the technology of biomass gasification and co-combustion of coal and gasification gas. For the sake of comparison, a coal and biomass direct coupling system is also introduced based on the technology of co-combustion of coal and biomass. The process of the direct and the indirect coupling system is simulated. The thermodynamic and economic performances of two systems are analyzed and compared. The simulation indicates that the thermodynamic performance of the indirect coupling system is slightly worse, but the economic performance is better than that of the direct coupling system. When the blending ratio of biomass is 20%, the energy and exergy efficiencies of the indirect coupling system are 42.70% and 41.14%, the internal rate of return (IRR) and discounted payback period (DPP) of the system are 25.68% and 8.56 years. The price fluctuation of fuels and products has a great influence on the economic performance of the indirect coupling system. The environmental impact analysis indicates that the indirect coupling system can inhibit the propagation of NO_x and reduce the environmental cost.     

2020年国内外宏观经济形势分析及预判

2020年,预计全球贸易进展局势出现缓和,世界经济增长小幅回升至2.6%左右,主要经济体面临的贸易政策、货币政策和地缘政治局势等不确定性因素仍较多,世界经济增长面临的下行风险仍较大。2019年中国经济总体平稳,GDP增长6.1%。2020年我国经济将继续保持增长稳健、结构优化、动能转换的发展态势,预计将实现6.0%的增长。     

浅谈高压中速磨粉系统在磷酸二铵生产中的应用

通过对磷酸二铵生产造粒特性分析,高压中速磨粉机原理分析,结合实践生产中的工艺需求,利用高压中速磨粉系统将颗粒状不合格品磨成细粉后添加进系统重新喷浆造粒,提高返料添加量,减少不合格品的产生,腾空仓库有限货位,以获取更大的经济价值。