U型埋管传热数值模拟及恒热流模型分析

对于地源热泵来讲,全面了解地下埋管周围的土壤温度场分布与变化状况十分重要。利用Matlab中的PDE工具箱建立了考虑实际钻孔半径、回填材料和U型管材料的竖直U形埋管与土壤的二维非稳态传热模型来模拟热泵运行72h内对周围土壤温度场的影响,并与常用的恒热流传热模型计算的结果进行对比分析。结果显示以2~3m为半径进行埋管可以有效避免地热井间的干扰问题;线源模型与柱源模型相比较,线源模型计算的孔壁温度能够更好更快地趋近于数值模拟结果。线源模型在工程实践中应用价值更高。     

CFX4中常用模型在复杂流动中适用性分析

目前商用流体力学被广泛用于工业的流动分析,但是对其模拟复杂流动的适用性和精确度等的认识还不够.通过数值计算和实验的对比分析,对CFX4提供的常用的标准k-ε模型、RNGk-ε模型以及低雷诺数k-ε模型在模型参数缺省的情况下计算值的准确性作了较为详细的评价.结果发现,数值计算值的准确性与流动的复杂性有关.对所讨论的两种流动,标准k-ε模型和RNGk-ε模型给出了与实测值较为一致的结果,而低雷诺数k-ε模型与实测结果存在较大出入.因此,在没有实验资料进行模型验证的情况下,标准k-ε模型和RNGk-ε模型可能是一个较好的选择.     

Flow field simulation and establishment for mathematical models of flow area of spool valve with sloping U-shape notch machined by different methods简

Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape notch on the spool, such as mass flow rates, flow coefficients, effiux angles and steady state flow forces under different operating conditions. At last, the reliability of the mathematical model of the flow area for the sloping U-shape notch orifice on the spool was demonstrated by the comparison between the orifice area curve derived and the corresponding experimental data provided by the test. It is presented that the bottom arc of sloping U-shape notch （ABU） should not be omitted when it is required to accurately calculate the orifice area of ABU. Although the theoretical flow area of plain bottom sloping U-shape notch （PBU） is larger than that of ABU at the same opening, the simulated mass flow and experimental flow area of ABU are both larger than these of PBU at the same opening, while the simulated flow force of PBU is larger than that of ABU at the same opening. Therefore, it should be prior to adapt the ABU when designing the spool with proportional character.     

助熔剂法生长二钛酸钡单晶

针对二钛酸钡仅在一窄小的温度区间热力学稳定,其单晶制备比较困难的问题,首次利用助熔剂法生长二钛酸钡单晶.以合成的二钛酸钡粉末为前躯体,以偏硼酸钡为助熔剂,以少量氧化硼为相稳定剂,二钛酸钡和偏硼酸钡的摩尔比为2∶3,二钛酸钡和氧化硼的摩尔比为1∶0.25,泡料温度为1 180℃,降温速率为3.3℃/h.温度降至1 080℃时,终止温度程序,使其自然降至室温.成功地生长出了二钛酸钡单晶,晶体尺寸大约为2.5 mm×0.3 mm×0.3 mm.     

Analysis of magnetotail flux rope events by ARTEMIS observations

Three earthward flowing magnetic flux ropes observed in the duskside plasma sheet at geocentric solar magnetospheric coordinate X~–55 Re by P1 and P2 of acceleration,reconnection,turbulence and electrodynamics of moon’s interaction with the sun mission during 13:00–15:00 UT on July 3,2012,were studied.The morphologies of the flux ropes were studied in detail based on Grad-Shfranov reconstruction method and electronic pitch angle distribution data.It is found that(1)the flux rope cross-sectional dimensions are 1.0 Re×0.78 Re,1.3 Re×0.78 Re,and 2.5 Re×1.25 Re,respectively.The magnetic field lines were asymmetric about the center with field line compression on both sides of the current sheet at the leading region;(2)the electron energy flux data presented asymmetry with larger electron flux and lower temperature in the precursor region.The flux ropes were blocked by the resistance of compressed particle density in the front central plasma sheet and the enhanced magnetic field on its sides;and(3)it is found that the flux rope has a layered structure.From inside out,event 1 can be divided into three regions,namely electronic depletion core region,closed field line region,and the caudal area possible with fields connected with the ionosphere.It suggests that the flux ropes cannot merge with the tail magnetic field lines near the lunar orbit.Especially,the flux rope asymmetrical shape reflects the different reconnection processes that caused it on both sides of the magnetic structure.The events shown in this paper support the multiple X-line magnetic reconnection model for flux ropes with in situ observations.     

完全混合式水解酸化工艺处理城市生活污水的研究

采用带有缓慢搅拌装置的完全混合式水解酸化工艺处理城市生活污水。结果表明,废水经水解酸化处理后的SS,CODCr和BOD5的去除率分别可达到70%,45%和36%;废水的平均B/C由进水的0.22提高到0.39。这样不仅废水的污染程度得到了一定的降低,而且可生化性也得到了较大的改善。T和pH对水解酸化反应器废水处理效果影响不大。     

漏磁法管道在线检测计算机系统

叙述了管道腐蚀缺陷检测的意义,提出了管道内在线检测对管线及时维护、管道寿命评价的必要性．介绍了漏磁法无损检测的基本原理,叙述了漏磁法管道在线检测计算机系统的总体设计、结构及各部分的工作过程．该系统具有检测速度快、效率高等特点,对管道的维护具有重要意义．     

差压法测量油水两相流流量

油水两相流的流动机理十分复杂,存在着"乳化"、"反相"等特有现象,其流量测量有很大难度。差压法作为一种应用广泛的流量测量方法,从原理上来看适用于油水两相流的流量测量,但相关研究较少。采用文丘里管作为节流装置,实现了油水两相流流量的差压测量。实验中以均相流模型为基础,以混合前测量的油水流量作为参考值,验证了文丘里管的差压值分别与质量流量计输出的体积流量值和混合密度值组合测量的效果。实验结果表明,油水总质量流量的测量精度较高,文丘里管与混合密度组合时精度尚可,与体积流量组合时达不到测量要求。     

Defect production and atomic mixing by displacement cascades in Ni_3Al

Molecular dynamics simulations have been employed to investigate displacement cascades in Ni3Al, with energy Ep in the range from 0.15 to 10 keV. The efficiency of production of Frenkel pairs declines with the increasing cascade energy in a fashion similar to that found recently for pure metals. The antisite defects are much more numerous than the Frenkel pairs, and their production efficiency increases with the increasing cascade energy. A new empirical relationship between the defect number and damage energy is proposed, namely Ndefect = AEpm. A high proportion of the atomic mixing occurs in the ballistic phase and is larger for the Ni atoms, implying that the phenomenon is not purely a liquid-like process.     

掺炭煅烧法制备α-磷酸三钙粉体

以四水硝酸钙和磷酸氢二铵为主要原料,采用湿化学合成法制备了α-磷酸三钙(-αTCP)粉体,研究了煅烧过程中添加分散剂活性炭防止磷酸三钙在高温煅烧时发生团聚的作用。采用X射线衍射仪、扫描电子显微镜和激光粒度分析仪对样品的物相、显微结构及粒度分布进行观察与分析。结果表明,当煅烧温度为1 320℃时,晶型完全转变,能够制备纯度较高的α-磷酸三钙粉体。活性炭掺量煅烧对α-磷酸三钙的粉体形貌和粒度有很大影响,当m(粉末)∶m(活性炭)=1∶0.5时,煅烧后的α-磷酸三钙粉体颗粒的形态分布更均匀,颗粒的中粒径更小,粒径分布主要集中在1.46μm左右。     

含铌铁水采用BaO基熔剂氧化脱磷的实验研究

利用BaO-BaC12(BaF2)-Fe203系熔剂,对含铌铁水进行氧化脱磷处理,研究了含铌铁水脱磷过程中铌磷的氧化行为,以及氧化剂加入量、助熔剂类型和温度等对铌、磷氧化的影响.实验结果表明,在铁水脱磷过程中铌也发生氧化.     

统一潮流控制器稳态潮流单独调节方法的研究

研究了ＵＰＦＣ在系统中实现有功功率和无功功率单独调节的可能性,并给出了实现该控制方式时求解控制量的解析表达式及其仿真结果,文章还给出了一种衫的有功和无功功率单独调节方法。     

高强混凝土的配制与基本性能

通过砂、石骨料的级配优化 ,采用 52 5 #普通硅酸盐水泥和复合型高效减水剂 ,配制出实用的75N·mm- 2 ～ 85N·mm- 2 高强混凝土 ,研究了水泥用量、水灰比、砂率、高效减水剂掺量对混凝土拌和性能、力学性能的影响规律 ,为活性矿物掺合料匮乏地区的高强混凝土配合比设计和工程应用提供了科研依据     

平衡施肥对稻田产量和土壤养分的影响

分析了水稻田土壤营养状况，土壤中N、P、K、Zn、Mn、Si等对沈农606超级稻的营养特性、吸肥规律、以及产量、质量的影响。对平衡施肥和生物肥技术进行了实验研究。试验区土壤有机质含量处于一般水平，土壤速效N、P、K、Zn及Mn普遍缺乏；N、K、Mn、Zn、Si均为产量限制因子。应用高产优质平衡施肥技术可以显著增加作物产量，多点平均产量为12．58t／hm^2，较习惯施肥区产量增加1．46t／hm^2，增产13．13％。     

平衡施肥对稻田产量和土壤养分的影响

分析了水稻田土壤营养状况,土壤中N、P、K、Zn、Mn、Si等对沈农606超级稻的营养特性、吸肥规律、以及产量、质量的影响。对平衡施肥和生物肥技术进行了实验研究。试验区土壤有机质含量处于一般水平,土壤速效N、P、K、Zn及Mn普遍缺乏;N、K、Mn、Zn、Si均为产量限制因子。应用高产优质平衡施肥技术可以显著增加作物产量,多点平均产量为12.58t/hm2,较习惯施肥区产量增加1.46t/hm2,增产13.13%。     

混合传质限速步骤及评价指标混合因子

为提高水处理混合工艺的效能,须对混合传质进行有效控制及效果评价.通过动力学和数学分析,研究湍流条件下的物质扩散规律,提出亚微观扩散是传质的限速步骤,增加混凝剂投加均匀度可有效缩短混合时间(t),以n表示投药点数时,缩减系数为π2/(π+n)2;基于传统评价方法中存在的混合效率与能耗脱节的不足,提出并定义"混合因子(IH)"这一新参数,以度量单位能耗对混合剂扩散均匀程度的贡献度.作为一项反映混合效率与能耗的综合指标,IH可对不同混合装置的效能进行更为合理的评价与比较.     

BaCO3基熔剂对锰铁熔体脱磷的实验研究

1 300 ℃时,在硅钼棒炉中采用BaCO3-BaF2-MnO2系熔剂对w([Si],i)＝0.084%～0.245%的锰铁合金进行脱磷实验.结果表明,只要改变渣系组成和脱磷处理时间适当,对不同硅含量的锰铁合金均可获得50%以上的脱磷率.采用BaCO3(w(BaCO3)＝60%～70%)-BaF2(w(BaF2)＝10%)-MnO2(w(MnO2)＝20%～30%)渣系脱磷时,锰的氧化损失为负值.脱磷保锰的最佳处理时间为10～15 min,脱磷过程中熔体氧位在5 min内迅速上升到一定值,5 min后氧位在很窄的范围内波动.改变渣系组成:MnO2的质量分数降到10%,BaCO3的质量分数从60%增至80%,对熔剂的最大脱磷率和其对应的氧位影响不大,最大脱磷率为49.1%～56.2%,对应氧位在0.35×10-6～0.50×10-6之间变化.     

Characterization of polysulfone hollow-fiber ultrafiltration membrane and its cleaning efficiency by streaming potential and flux method

Polysulfone (PS) hollow-fiber ultrafiltration membrane was characterized combined with flux and streaming potential in single electrolyte solutions. The effects of trans-membrane pressure, electrolyte concentration, ion valence and pH value of electrolyte solution on the streaming potential (SP) of the membrane were investigated. The zeta potential and surface charge density of the membrane were calculated on the basis of Helmholtz-Smoluchowski equation and Gouy-Chapmann theory. The results indicate that the valence and concentration of cation have a greater influence on the SP and surface charge density of PS membrane than those of anion, and the pH value of electrolyte solution has great effects on the SP and zeta potential of the membrane surface. Both the absolute value of the streaming potential and water flux of the adsorbed membrane decrease, compared with those of the clean membrane. The streaming potential and flux of the cleaned membrane can be completely recovered by cleaning with the mass fraction of 0.8% EDTA at pH=10. Foundation item: Project(20776161) supported by the National Natural Science Foundation of China     

多头深层搅拌桩截渗墙在涡阳枢纽深孔闸工程中的应用

文章分析了运用多头深层搅拌桩垂直截渗墙解决砂基防渗及抗地震液化问题的工艺措施及技术参数,指出防渗效果。