空间碎片超高速碰撞的数值方法研究

应用非线性动力学数值仿真软件AUTODYN-2D对空间碎片的超高速碰撞问题进行模拟,研究不同数值计算方法和材料模型的适用范围,空间碎片形状对碎片云的影响,冲击相变等问题。结果表明,在研究超高速碰撞中普遍采用的SPH方法可以很好地模拟碎片云的情况,但是难以对冲击相变问题进行模拟,而采用侵蚀模型的拉格朗日方法可较好地反映冲击相变现象。Tilloston状态方程适用于描述冲击相变问题,包括汽化问题。Johnson-Cook强度模型用来对应变硬化、应变率硬化以及熔化等问题进行模拟。因此,在当速度足以使材料发生相变时,Tilloston状态方程和Johnson-Cook强度模型是比较好的选择。     

Polymer Supported Calix[4]Arene Derivatives for the Extraction of Metals and Dichromate Anions

Three newly synthesized polymer supported calix[4]arene ionophores (7–9) were synthesized, and their ion binding properties toward selected alkali (Li⁺, Na⁺, K⁺, Cs⁺) and transition metal (Hg²⁺, Ni²⁺, Cu²⁺, Co²⁺, Cd²⁺, and Pb²⁺) cations were investigated. It has been observed that these ionophores are not selective toward a particular metal cation but show better ion binding property as compared to monomeric calixarene derivatives (2 and 6). Ionophore 6 and its supported polymer were also employed in dichromate anion extraction experiments. The polymeric ionophore (9) was found an effective extractant for dichromate anion even at pH 7.     

Combustion,emission, and phase stability features of a diesel engine fueled by Jatropha/ethanol blends and n-butanol as co-solvent

ABSTRACT

The main challenge of utilizing ethanol in diesel engines in blending mode is the phase separation issue. Therefore, an attempt has been performed to enhance the stability feature of ethanol/Jatropha biodiesel (JME) blends by using n-butanol as co-solvent. The 10% by volume of n-butanol is added to the mixtures of 10% and 20% ethanol and 70% and 80% JME, which is denoted as JME10Bu10E and JME10Bu20E, respectively. The phase stability of the evaluated fuels is examined employing visual approach and Thermogravimetric analysis. These methods confirm that there is no phase separation for more than 2 months under ambient conditions. Then, the combustion and emission features are investigated utilizing a diesel engine run with different loads and constant speed. The findings demonstrate that the p_max. and HRR are increased by adding ethanol. The ignition delay is extended with the addition of ethanol while the combustion period is almost the same. The bsfc is decreased by adding ethanol compared to JME fuel. The CO, UHC, and NO_x formations are reduced markedly by 40%, 40%, and 40%, respectively, with adding ethanol. Finally, using n-butanol and JME as co-solvents with ethanol supports the growth of renewable energy in the CI engine.     

Investigations on an evacuated tube solar water heater using hybrid-nano based organic phase change material

ABSTRACT

This work explores the opportunities to address the setback in thermal energy storage of solar-based water heaters by uniting it with a suitable hybrid-nano composite phase change material (HNCPCM) in a static mode of operation. The experiments were conducted on a natural circulation all-glass evacuated solar water heating system (AGSWH). The investigation was steered in five cases such that the first case without any phase change material (PCM), the second with pure paraffin as PCM, and remaining three cases with three different mass percentage of HNCPCMs (0.5%, 1.0%, and 2.0% mass fraction of hybrid nanoparticles within PCM) in real-time solar exposure. The system was analyzed based on the first and second law of thermodynamics to assess the performance in all the five cases. Erstwhile, the hybrid nanoparticles were prepared by blending equal mass of SiO₂ and CeO₂ nanoparticles and characterized to gauge its thermal storage properties. The achieved results substantiated that the thermal conductivity had boosted with the accumulation of hybrid nanoparticles within the paraffin matrix, and maximum enhancement of 65.56% was attained with 2.0% mass fraction. The first law and second law investigations revealed that the incorporation of hybrid-nano composites improved the energy and exergy content of the system, distinctly. Among the experimented cases, HNCPCM with 1.0 mass% of hybrid nanoparticles remarkably yielded a better result of 19.4% and 1.28% improvement in energy and exergy efficiencies, respectively. Besides, it evidenced the necessity of choosing the right quantity of nanoparticles for achieving better overall results.     

液相法芒硝制碱中苛化废渣的利用

研究了用液相法芒硝制碱的苛化废渣制取轻质ＣａＣＯ３的工艺及用轻质ＣａＣＯ３填充母料对聚乙烯进行改性。试验结果表明,本研究所制取的轻质ＣａＣＯ３的质量符合ＧＢ４７９４－８４一级品规格,用其制成母料对低密度聚乙烯填充改性,不仅可消除苛化废渣对环境的污染,降低聚乙烯制品的生产成本,而且可在制品的拉伸强度、断裂伸长率和冲击强度降低不多的情况下,提高制品的硬度、弹性模量、热稳定性及耐蠕变性。     

Estrogen-related receptor disruption of source water and drinking water treatment processes extracts

Environmental chemicals in drinking water can impact human health through nuclear receptors. Additionally, estrogen-related receptors (ERRs) are vulnerable to endocrine-disrupting e ects. To date, however, ERR disruption of drinking water potency has not been reported. We used ERR two-hybrid yeast assay to screen ERR disrupting activities in a drinking water treatment plant (DWTP) located in north China and in source water from a reservoir, focusing on agonistic, antagonistic, and inverse agonistic activity to 4-hydroxytamoxifen (4-OHT). Water treatment processes in the DWTP consisted of pre-chlorination, coagulation, coal and sand filtration, activated carbon filtration, and secondary chlorination processes. Samples were extracted by solid phase extraction. Results showed that ERR antagonistic activities were found in all sample extracts, but agonistic and inverse agonistic activity to 4-OHT was not found. When calibrated with the toxic equivalent of 4-OHT, antagonistic e uent e ects ranged from 3.4 to 33.1 g/L. In the treatment processes, secondary chlorination was e ective in removing ERR antagonists, but the coagulation process led to significantly increased ERR antagonistic activity. The drinking water treatment processes removed 73.5% of ERR antagonists. To our knowledge, the occurrence of ERR disruption activities on source and drinking water in vitro had not been reported previously. It is vital, therefore, to increase our understanding of ERR disrupting activities in drinking water.     

铬掺杂TiO2液相沉积膜可见光下降解甲基橙研究

实验用液相沉积法制备铬掺杂改性的二氧化钛(Cr-TiO2)薄膜电极,并在可见光下利用制备的电极对甲基橙溶液(MO)进行光电降解实验研究.并对制备的薄膜进行光电流(I-t)、交流阻抗(EIS)和Mott-Schottky等电化学相关表征.当掺杂浓度为0.2％时,薄膜电极具有最好的光电催化活性.在以0.2％ Cr-TiO2...     

超快速液相色谱-串联质谱法测定制药废水中阿维菌素的研究

建立了采用固相萃取-超快速液相色谱-串联质谱（SPE-RRLC-MS/MS）测定制药废水中阿维菌素残留的方法.水样经离心、沉淀蛋白质后,上清液采用HLB固相萃取柱富集和净化;以0.1%甲酸水溶液和50%～90%甲醇为流动相,采用AgilentPlusC18柱进行RRLC分离,在串联质谱ESI（＋）模式下采用多反应监测模...     

沈阳卫工河水中多环芳烃的分布、来源及生态风险初步评价

卫工河水中6月(夏季)16种多环芳烃的含量为0.244～2.038μg·L-1,平均为0.768μg·L-1;9月(秋季)水中总多环芳烃(TPAHs)含量为0.503～0.989μg·L-1,平均0.761μg·L-1;11月(冬季)多环芳烃的含量为0.229～0.427μg·L-1,平均含量为0.346μg·L-1。个别地点苯并(a)芘含量明显高于国家地表水环境质量标准(GB3838-2002);对卫工河水中多环芳烃污染来源分析发现,多环芳烃的主要来源燃烧来源;通过商值法对卫工河的初步风险评价表明,卫工河水中苯并(a)芘存在较大的生态风险,应引起有关部门的进一步关注。     

厌氧型生物反应器产CH4期水解动力学模型研究

为研究渗滤液回灌和温度对填埋垃圾产CH4的影响,在不同温度下,通过对3个已进入产CH4期的厌氧型生物反应器实施不同的回灌操作,并根据p(CODCr)和产CH4速率的监测数据,建立了厌氧型生物反应器固相垃圾的水解模型.产CH4速率的模型计算的模拟值与D1,D2和D3柱实测值的相关系数分别为0.895 5,0.809 1和0.915 6,具有较高的可靠性.其中保持较高的产CH4速率且恒定温度的D2柱的固相垃圾水解系数是D1柱的12倍左右;同时随着回灌频率的降低,D3柱水解速率系数从0.007 6降到0.002 7,与D1柱的相对差也逐渐增大,保持较高的温度(35℃左右)和较高回灌频率有利于固相垃圾的水解和厌氧型生物反应器的快速稳定.