Numerical Study on the Two-Dimensional Temperature Fields of Titanium/Aluminum Double-Layer Target Irradiated by High-Intensity Pulsed Ion Beam

Interaction between high-intensity pulsed ion beam （HIPIB） and a double-layer target with titanium film on top of aluminum substrate was simulated. The two-dimensional nonlinear thermal conduction equations, with the deposited energy in the target taken as source term, were derived and solved by finite differential method. As a result, the two-dimensional spatial and temporal evolution profiles of temperature were obtained for a titanium/aluminum double-layer target irradiated by a pulse of HIPIB. The effects of ion beam current density on the phase state of the target materials near the film and substrate interface were analyzed. Both titanium and aluminum were melted near the interface after a shot when the ion beam current density fell in the range of 100 A/cm2 to 200 A/cm2.

Rapid genetic screening of Charcot-Marie-Tooth disease type 1A and hereditary neuropathy with liability to pressure palsies patients

We used the allele-specific PCR-double digestion method on peripheral myelin protein 22 （PMP22） to determine duplication and deletion mutations in the proband and family members of one family with Charcot-Marie-Tooth disease type 1 and one family with hereditary neuropathy with liability to pressure palsies. The proband and one subclinical family member from the Charcot-Marie-Tooth disease type 1 family had a PMP22 gene duplication; one patient from the hereditary neuropathy with liability to pressure palsies family had a PMP22 gene deletion. Electron microscopic analysis of ultrathin sections of the superficial peroneal nerve from the two probands demonstrated demyelination and myelin sheath hyperplasia, as well as an ＇onion-like＇ structure in the Charcot-Marie-Tooth disease type 1A patient. We observed an irregular thickened myelin sheath and ＇mouse-nibbled＇-Iike changes in the patient with hereditary neuropathy with liability to pressure palsies. In the Charcot-Marie-Tooth disease type 1A patient, nerve electrophysiological examination revealed moderate-to-severe reductions in the motor and sensory conduction velocities of the bilateral median nerve, ulnar nerve, tibial nerve, and sural nerve. Moreover, the compound muscle action potential amplitude was decreased. In the patient with hereditary neuropathy with liability to pressure palsies, the nerve conduction velocity of the bilateral tibial nerve and sural nerve was moderately reduced, and the nerve conduction velocity of the median nerve and ulnar nerve of both upper extremities was slightly reduced.

Numerical simulation and structure improvement of double throttling in a high parameter pressure reducing valve

In this paper, a new pressure reducing valve （PRV） with an orifice plate is proposed. The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV. A numerical simulation method was used to investigate the PRV internal flow field and to analyze the throttling effects of the orifice plate and the transform of thermal parameters as outlet pressure, outlet temperature, velocity, and superheat. A structure improvement method for the valve body and orifice plate is put forward to reduce energy loss. The governing equations for internal flow numerical simulation are composed of the continuity, momentum, energy and k-e transport equations, based on isotropic eddy viscosity theory. Different valve plug displacement models were built to describe the double throttling process. Our analysis shows that the steam pressure drops twice and the degree of superheat increases. There are also lots of eddies which clog the flow channel and disturb the steam flow in the valve cavity after the valve plug and the outlet cavity. After modifying the structure, the numerical results show a better performance of steam flow.

Finite element simulation of three-dimensional temperature field in underwater welding

Mathematical models of three-dimensional temperature fields in underwater welding with moving heat sources are built. Double ellipsoid Gauss model is proposed as heat sources models. Several factors which affect the temperature fields of underwater welding are analyzed. Water has little influence on thermal efftciency. Water convection coefftcient varies with the temperature difference between the water and the workpiece , and water convection makes molten pool freeze quickly. With the increase of water depth, the dimensions of heat sources model should be reduced as arc shrinks. Finite element technology is used to solve mathematical models. ANSYS software is used as finite element tool, and ANSYS Parametric Design Language is used to develop subprograms for loading the moving heat sources and the various convection coefftcients. Experiment results show that computational results by using double ellipsoid Gauss heat sources model accord well with the experimental results.

Natural Convection Heat Transfer in a Porous Cavity with Sinusoidal Temperature Distribution Using Cu/Water Nanofluid: Double MRT Lattice Boltzmann Method

In this study,natural convection flow in a porous cavity with sinusoidal temperature distribution has been analyzed by a new double multi relaxation time(MRT)Lattice Boltzmann method(LBM).We consider a copper/water nanofluid filling a porous cavity.For simulating the temperature and flow fields,D2Q5 and D2Q9 lattices are utilized respectively,and the effects of different Darcy numbers(Da)(0.001-0.1)and various Rayleigh numbers(Ra)(10^(3)-10^(5))for porosity(ε)between 0.4 and 0.9 have been considered.Phase deviation(θ)changed from 0 toπand the volume fraction of nanoparticles(∅)varied from 0 to 6%.The present results show a good agreement with the previous works,thus confirming the reliability the new numerical method proposed in this paper.It is indicated that the heat transfer rate increases at increasing Darcy number,porosity,Rayleigh number,the volume fraction of nanoparticles and phase deviation.However,the most sensitive parameter is the Rayleigh number.The maximum Nusselt deviation is 10%,32%and 33%for Ra=10^(3),10^(4) and 10^(5),respectively,withε=0.4 toε=0.9.It can be concluded that the effect of Darcy number on the heat transfer rate increases at increasing Rayleigh number,yielding a maximum enhancement of the average Nusselt number around 12%and 61%for Ra=10^(3) and Ra=10^(5),respectively.

Pressure Transient Analysis of Arbitrarily Shaped Fractured Reservoirs

Reservoir boundary shape has a great influence on the transient pressure response of oil wells located in arbitrarily shaped reservoirs. Conventional analytical methods can only be used to calculate transient pressure response in regularly shaped reservoirs. Under the assumption that permeability varies exponentially with pressure drop, a mathematical model for well test interpretation of arbitrarily shaped deformable reservoirs was established. By using the regular perturbation method and the boundary element method, the model could be solved. The pressure behavior of wells with wellbore storage and skin effects was obtained by using the Duhamel principle. The type curves were plotted and analyzed by considering the effects of permeability modulus, arbitrary shape and impermeable region.

温度影响下不同轴压比双钢板混凝土组合剪力墙抗震性能

研究不同温度环境下不同轴压比双钢板混凝土组合剪力墙的抗震性能,以温度(40、20、-40℃)和轴压比(n=0.3、0.4、0.5、0.6)为控制参数,设计了12片剪力墙。利用ABAQUS对双钢板组合剪力墙试验进行对比验证,验证有限元结果的准确性。通过对12个剪力墙的承载能力、塑性变形能力、耗能能力、延性对比分析,探究其在代表性温度环境下轴压比对试件的抗震性能变化规律。结果表明,在相同的温度环境下,随着轴压比的增加,剪力墙的承载能力增加,延性降低。轴压比对于刚度退化的影响不明显。在20℃环境下,剪力墙的延性好于40和-40℃环境下延性。-40℃环境下,剪力墙的承载能力高于40和20℃环境。

双层定型相变墙体在合肥地区传热特性的数值模拟

为探究双层相变墙体所使用的相变材料在不同季节下的相变表现,以合肥地区夏、冬两季室外温度数据为背景,基于Fluent焓-孔隙率法,对普通墙体和双层相变墙体的传热过程进行仿真计算。结果表明,在夏季工况下,外相变板的相变温度为36℃的相变墙体综合表现更好,墙体内表面热流密度与普通墙体相比降低了20.53%,平均延迟时间约为普通墙体的1.8倍。在冬季工况下,内相变板的相变温度为14℃的相变墙体内表面温度波幅较平缓,墙体内表面热流密度与普通墙体相比降低了16.25%,它的衰减倍数约为普通墙体的1.2倍。在合肥地区,使用相变温度为36℃的外相变层和相变温度为14℃的内相变层的墙体在制冷、采暖期单位面积可降低热/冷负荷分别为1.86 W、3.75 W,该种墙体具有很好的节能效果和经济效益。

计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算

文中提出一种计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算,基于Simulink对短时间尺度下损耗与结温的相互依赖关系进行更新,并分别通过双脉冲测试及有限元仿真修正长时间尺度下键合线与芯片焊料层老化对IGBT结温计算的影响,在此基础上,根据芯片焊料层不同老化状态下键合线的应力特征,实现两种老化模式的相互关联,较为准确地计算IGBT结温。最终利用试验平台与传统结温计算方法进行对比验证了所提结温计算方法的准确性。该结温计算方法有助于在实际运行工况及IGBT模块老化状态下精确计算结温。

柴油引燃天然气火焰温度场和碳烟浓度场分析

针对柴油引燃高压直喷天然气火焰温度场和碳烟浓度场尚不明确的问题,在定容燃烧弹平台上,采用高压直喷天然气共轴喷射器,利用高速彩色相机结合双色法研究了不同油/气喷射压力和油/气喷射间隔对高压直喷天然气燃烧后的火焰温度和碳烟KL值分布特性。研究结果表明:高压天然气被引燃后的火焰平均温度和碳烟平均KL值均随着油/气喷射压力的升高而降低,因此为降低碳烟KL值应提高油/气喷射压力。当油/气喷射间隔为0.8 ms时,高压天然气射流火焰平均温度最高,最高达到2318 K;当喷射间隔为0.4 ms时,火焰的平均温度最低,最低为2148 K;相同时刻下,油/气喷射间隔0.8 ms的碳烟平均KL值相较于0.4 ms的工况最多提高了112.8%,相较于喷射间隔1.2 ms的工况最多提高了49.02%;试验结果表明:为降低高压直喷天然气燃烧时的碳烟生成水平,应将喷射间隔设定在柴油喷射结束之前。本文为HPDI天然气发动机的燃料喷射策略和降低碳烟生成的相关研究提供基础参考。

硬密封双偏心球阀反向承压密封问题有限元研究

应用ANSYS软件对通径DN300、工作压力3.5 MPa、工作温度500℃的硬密封双偏心球阀反向承压密封面接触问题进行了非线性有限元分析,得到阀门关闭时在反向承压状态下有无预压紧条件下,硬密封双偏心球阀的应力应变图。通过有限元计算结果分析得到了硬密封双偏心球阀应用可移动阀座,并且通过对其预加合适的压紧力,能够更好地实现反向承压密封。同时分析结果还表明,双偏心球阀的阀板容易发生变形,变形会影响阀板和阀座的密封配合,双偏心球阀的阀板必须保证一定的刚性。理论和实践研究结果表明,阀座选用浮动形式的结构,通过预压紧提供初始密封压紧力后,通过阀内液体作用于阀座,阀座压紧阀板为密封提供压紧力实现密封的技术更适合双偏心球阀。研究对“双向零泄漏”硬密封双偏心球阀的结构设计有指导意义。

Gd_(2)MgTiO_(6):Dy^(3+)荧光粉的制备与发光性能研究

采用高温固相法制备出一系列Dy^(3+)掺杂双钙钛矿Gd_(2)MgTiO_(6)白色荧光粉样品,通过X射线衍射仪和荧光光谱仪对荧光粉样品的晶体结构及荧光性能进行分析和表征。结果表明:在355 nm近紫外光激发下,样品发出极强的蓝光(484 nm)和黄光(575 nm)。通过调节Dy^(3+)的浓度可以使样品发光颜色向白光区移动,因此Gd_(2)MgTiO_(6):Dy^(3+)是一种可调荧光粉。当Dy^(3+)掺杂浓度为3%时可以发出色坐标为(0.3598,0.3946)的白光。Gd_(2)MgTiO_(6)合成方法简便、组份易调控,是一种具有潜在应用价值荧光材料。

新景矿带压开采技术研究

新景矿的煤层都具有良好的隔水层,但是在开采时仍有突水的可能性。因此,为了保证开采的安全性,需要对新景矿的地下水带压开采进行评价。在带压开采评价时,采用了五图-双系数法,双系数的取值均为0.06 MPa/m。研究结果表明,3^(#)、8^(#)、9^(#)、15^(#)煤层带压开采时,在井田内双系数均小于0.06 MPa/m,正常情况下,发生突水的可能性极小。可以为煤矿带压开采提供一定的参考。

dDNP溶融系统的自动化设计与研究

溶融动态核极化(dDNP)是一种将分子样品在超低温、强磁场以及微波照射下高度极化,然后经高温高压溶剂快速溶解后立即转移至NMR/MRI系统进行检测的灵敏度增强技术.溶融系统是实现这一过程的关键部分,其性能直接影响样品的溶融、转移效率以及样品极化度的保留程度.本文提出了基于双闭环PID控制算法的自动化溶融系统的控制方案,可在9 min以后达到目标压强1.7 MPa左右并使内部压强被动控制在1.5%以内.将研制的自动化溶融系统集成于自主开发的5 T dDNP仪器系统,可将−271℃的低温样品快速溶融,并于4 s内将其转移到距离11.2 m处的7 T NMR系统进行检测,获得了[1-^(13)C]-丙酮酸钠在溶融态下^(13)C NMR信号9050倍的增强.自动化溶融系统简化了操作步骤,提高了实验的安全性和一致性.

基于降雪识别的河南省降雪及降雪比率时空变化特征

使用河南省119个国家级地面气象观测站近52年(1968-2019年)的气象资料,利用日天气现象对日降水相态进行标记,运用加入指数方程拟合的双温度阈值法,构建了本地化分区域的降雪识别方法,通过降雪识别得到较为准确的降雪量后,研究了河南省近52年降雪和降雪比率时空变化特征。结果表明,加入指数方程拟合的双温度阈值法在河南省降雪识别中具有较高的精度,降雪识别指数方程估算的年降雪量和总降雪量在5个区域的相关系数均达到0.96以上。河南省近52年年平均降雪量为10~50 mm,降雪大值区位于豫西区域东南部和豫南区域东南部;全省年降雪量以-0.87 mm/10a的速率减少,各区域的年降雪量下降速率按照豫北、豫中、豫西、豫东、豫南的顺序依次增大;降雪期内各月份降雪量按照4月、11月、3月、12月、2月、1月的顺序递增,其中11月降雪量呈增长趋势,12月、2月和3月降雪量呈减小趋势。近52年降雪期内降雪比率为0.13~0.44,呈现出西高东低、北高南低的特征;降雪期内全省降雪比率以-0.0092/10a的速率下降,各区域降雪比率下降速率按照豫西、豫北、豫中、豫南、豫东的顺序依次增大,降雪比率较大的豫西、豫北区域下降速率较小,降雪比率较小的豫南、豫东区域下降速率较大;从站点分布来看,全省78%的站点降雪比率呈下降趋势,22%的站点呈上升趋势,呈上升趋势的站点位于豫西区域和豫北区域,呈下降趋势的站点位于豫东、豫南和豫中区域。

双消浪室有顶板开孔沉箱数值研究

采用基于泰勒级数展开的CSPH(corrective smoothed particle hydrodynamics)方法和Riemann解改进了光滑粒子流体动力学(SPH)方法,模拟了波浪与双消浪室有顶板开孔沉箱的相互作用。通过与试验数据的对比,验证了数值方法的准确性和适用性。分析了顶板高度s、消浪室宽度B和开孔率μ等因素对沉箱附近波面η和水平波压力p的影响。结果表明:在计算波浪条件下,顶板高度s和开孔率μ是沉箱波面峰值的主要影响因素,而消浪室宽度B对波面峰值的影响较小;同时,随着顶板高度s的增加,静水位处前开孔板和后实体墙的波压力峰值均逐渐减小,而后开孔板的波压力峰值先减小后增大。此外,改进后的SPH方法还可用于研究水粒子的压力场和速度场的情况,追踪水粒子在不同位置、不同时刻的瞬时速度,描述水粒子的运动状态,为研究波浪和开孔沉箱的相互作用提供了有效手段。

钱塘江底地铁联络通道双侧发散布孔的冻结温度场实测

钱塘江底地层富含气及动水,会明显影响江底联络通道冻结施工的温度场演变过程和分布特征。为解决该问题,通过对位于钱塘江底的杭州地铁6号线某联络通道冻结工程进行现场监测,研究冻结施工中不同位置地层温度的演变过程,分析停冻后冻结管内的温度变化特征,获得地层中含气及地下水流动对联络通道冻结温度场的影响规律。1)双侧发散布孔时,冻土向内平均发展速度是向外的1.47倍,而停冻6 h后外排和内排冻结管内的温度分别回升5℃和10℃;2)地层中囊状气泡削弱了冻结管向周围土体的冷量传递过程,从而明显影响冻结效果,冻结过程中气泡位置的温度比冻结管终端位置偏高8~18.4℃;3)地下水流动也会影响地层中的冷量分布,冻结57 d时冻结壁上、下游对应位置冻结管内温度相差8℃,而停冻6 h后相应位置的冻结管内温度分别回升了5℃和2℃。研究结果表明:双侧隧道内发散布孔方式可以有效解决含气及动水地层中影响联络通道冻结施工的问题,而地层中囊状气泡和地下水流动都会明显影响冻结温度场的分布特征。

双加压硝酸生产设备腐蚀分析与防护研究

为进一步探究双加压硝酸生产设备的腐蚀防护问题,本文结合某化工厂现存的吸收塔冷却盘管腐蚀损坏问题,通过模拟实验和机理分析两方面的措施,研究其腐蚀原因,最终确定造成吸收塔冷却盘管腐蚀的原因是冷却水中氯离子含量偏高和盘管连接模式不合理。由此,在吸收塔的第9~15层安装脱氯装置,并使用直接热弯管工艺取代传统焊接工艺,以进行腐蚀防护,从实际应用结果来看,上述措施取得了一定的防护效果。

大直径灌注桩桩身完整性综合判定及缺陷处理

桩身完整性是制约大直径灌注桩承载力发挥的关键因素之一。文中以闽东某工程为例,分析低应变法、声波透射法、钻芯法等特点,运用多种检测方法综合分析判定完整性类别,基于检测结果进行缺陷原因分析及处理。结果表明,在工程实践中,应综合运用多种检测方法分析缺陷在桩身横向和纵向的分布占比,并考虑缺陷的类型和严重程度,综合分析判定完整性类别,对于大直径灌注桩较深部位的局部缺陷,利用钻芯孔并采用双重管高压注浆法处理是可行、有效的。

成都地区大断面矿山法隧道工法研究

成都轨道交通从2005年开工建设至今19年,目前已经开通14条地铁线路,通车里程600 km。成都属于冲击平原,在地铁施工的工法选择上,车站主要采用明挖或者盖挖法实施,区间主要采用土压平衡盾构法施工。而当受到外部条件限制时,也会选择矿山法进行施工。文章首先介绍了成都地区地质情况,然后介绍成都地区主要的矿山法形式及适用特点,对成都地铁既有矿山法工程进行了详细阐述。依托既有工程经验,结合这些常用工法的优缺点,提出一种新的矿山法形式,并对该技术方案进行详细的研究分析。