电石渣制备高强度氧化钙及其含碳球团循环生产电石

电石及乙炔生产过程中产生大量电石渣及细颗粒的兰炭粉,目前尚无大量消纳的利用途径。为了解决煤基电石行业的能源与环境问题,提出利用电石渣制备块状CaO或者与兰炭粉共成型制备CaO含碳球团,用于电石生产的新工艺,该工艺特点在于利用电石渣与兰炭粉为原料,实现工业固废回收利用;同时通过共成型增大原料间的接触面积,改善电石制备反应动力学条件。</p

The Effect of the Replacement of Business Tax by VAT on Business Investment,R&D and Labour Employment: A DID Model Analysis Basing on Chinese Listed Company's Data

逐步推广的“营改增“改革相当于一种“自然实验“,本文选取了239家上市公司2007-2013年的面板数据,用双重差分模型研究了该政策对企业投资、劳动雇佣以及研发行为的影响。结果表明,“营改增“显著促进了企业总投资,不过在房地产市场及企业规模等因素的干扰下,对设备类固定资产及部分无形资产投资促进作用并不明显,不过人均资本量却得到了显著提高;“营改增“对劳动力雇佣没有实际影响,但显著提高了工资水平;同样,改革也在一定程度上有益于企业研发投入。根据研究结果,本文也对“营改增“后续改革提出了政策建议。Taking use of the panel data of 239 Chinese listed companies from 2007 to 2013,the paper analyzes the effect on business investment,R&D and labour employment of the replacement of business tax by VAT policy which can be seen as a natural experiment.Our analysis shows that the policy obviously increased the total investment of companies while the improvement effect on machine and equipment assets as also as intangible assets was not so obvious because of the real estate market and the company scale.The policy also weakly reduced the labour employed and improved the average pay level at the same time.At last the study told us the policy was helpful to increase the R&D investment to some extent.Our paper also gives some suggestions for the following tax reform.国家自然科学基金项目(71373220); 国家社科基金项目(13BJY149); 中央高校基本科研业务费(2009ZK1007)的资

高温CO2热泵的超临界喷气增焓性能

提出了一种基于高温超临界喷气增焓技术的新型CO2热泵循环,以显著提升跨临界CO2热泵在高温循环加热工况下的制热性能。通过建立超临界喷气增焓型高温CO2热泵系统的数值模型,并采用EES(engineering equation solver)软件对该热泵系统的循环加热性能进行了仿真分析。研究了在较高气体冷却器出口温度下,蒸发温度、压缩机中间压力、气体冷却器压力等参数对单位容积制热量和性能系数(COP)的影响。结果表明:在最优排气压力下,气体冷却器出口温度高达60℃时,该热泵循环的COP也能达到3.0左右;相对于普通喷气增焓系统,COP明显提高;相对于无喷气增焓的常规系统,在气体冷却器出口温度为60℃时,相对补气量为0.3、0.4、0.5的超临界喷气增焓系统COP分别提高了14.8%、21.2%、29.2%;气体冷却器压力和中间压力对系统COP的影响变化趋势一致,但气体冷却器压力的影响更为显著;此外,存在最优的气体冷却器压力和中间压力使系统COP达到最大,在气体冷却器出口温度为60℃,相对补气量为0.4时,最优气体冷却器压力和中间压力分别为13.5MPa和8.5MPa

耦合过热蒸汽干燥的MVR蒸发结晶系统热力性能分析

机械蒸汽再压缩(MVR)作为目前最先进的蒸发结晶技术得到广泛关注和应用,本文结合过热蒸汽干燥技术的优势,提出一种耦合过热蒸汽干燥的MVR蒸发结晶干燥系统。基于EES软件建立数值模型,通过系统仿真的方法分析闪蒸压力pflash、进料浓度c0、循环倍率CR、换热温差ΔTmhex等对压缩机能耗Wcomp和系统能效系数COP、下降管结晶盐含水率的上限值ω和换热器UA值的影响情况。结果表明:耦合过热蒸汽干燥的MVR系统相比常规系统具有更高的COP、更低的Wcomp,并且能够获得干燥的结晶盐;循环倍率CR增大,压缩机压比π降低,有利于提高COP和降低Wcomp,但同时换热器UAmhex值会增大,设备成本增加;系统COP随pflash的变化关系与循环倍率CR有关,CR较低时,随Pflash的增大,系统COP增大,CR超过某一定值,随着pflash的增大,系统COP呈先升后降趋势,其最大值在pflash为40~50kPa;进入干燥器的下降管结晶盐含水率的上限值ω与进料浓度c0有关,随进料浓度c0的升高而增大;ΔTmhex对MVR系统性能有显著的影响,ΔTmhex每增大1K,COP平均降低5.6%、Wcomp平均升高5.8%、UAmhex平均减少14.4%,ω平均升高1.7%

喷气增焓型单级MVR蒸发结晶系统性能分析

针对工业废水蒸发结晶过程中含盐浓度增大、从而导致沸点升和增压比偏高等问题,提出了喷气增焓型单级机械式蒸汽再压缩(MVR)蒸发结晶系统。基于EES软件建立了喷气增焓型单级MVR蒸发结晶系统数值模型,并研究了闪蒸压力Pflash、物料入口浓度c0、物料循环倍率CR、换热温差ΔTpreh和ΔTmhex以及补气压比指数n和补气率βv对系统热效率COP、单位闪蒸量的压缩机耗功wcomp、压缩机出口蒸汽过热度Δtsuph和换热器UA值等参数的影响。结论如下:喷气增焓型MVR系统相比无喷气过程的单级MVR蒸发结晶系统具有更高的COP、更低的wcomp以及更小的Δtsuph;随CR增大,压缩机增压比降低了32.8%,COP提高了54.8%;随Pflash增大,COP呈先降后升趋势,在30~35kPa时存在最低值;换热系统中,主换热器温差ΔTmhex对MVR系统性能影响更为显著,ΔTmhex每增大1K,COP平均降低4.0%、wcomp平均升高4.9%、UAmhex平均增加8.9%

Large Scale LURR Anomaly before Wenchuan Earthquake

孕震初期加卸载响应比(LURR)通常在1左右涨落,然后逐渐上升至峰值点。但强地震并不在峰值点上发生,而要滞后一段时间(T2)。T2与震级有关,震级越大,T2越长。对于8级地震,T2的计算值为28±8个月,汶川8级地震实际的T2是23个月。对于大地震,T2很长,峰值点后LURR通常迅速下降,在大地震前夕LURR常常降得很低,而预测的地震又迟迟没有发生,这种情况下很容易误导人们怀疑,甚至放弃原来的预测,殊不知,这时大地震正在迫近。这正是汶川8级地震给予人们血的教训。大地震不仅孕育时间长,孕震区面积也很大。大地震的前兆在时空上都是大尺度。基于这种认识,根据LURR的演化,中国大陆西南地区可能正在孕育一个特大地震

The peak point of LURR and its significance

The Load/Unload Response Ratio (LURR) value fluctuates around one during the early stage of the seismogenic process and then rises and reaches its peak point before the occurrence of a strong earthquake; the strong earthquake however does not onset at that time, but after the peak point LURR decreases sharply at the eve of the main shock before the final event outbreak. Thus, the peak point of LURR is ahead of the occurrence of an earthquake. We denote the lead time as T(2). The discovery of peak point for LURR and the relationship between T(2) and magnitude M is of great significance as the peak point is usually easy to determine and then we can predict the occurrence time for the coming event according to Equation (3) so that we can enhance the precision of time for earthquake prediction in terms of LURR from &#39;year&#39; scale to &#39;month&#39; scale. The variation of LURR around the Wenchuan earthquake and its lesson to us are depicted in the paper.</span