Effects of Pre-Diffuser on Performance of Dump Diffuser

研究了突扩扩压器中前置扩压器各参数与总压损失和静压恢复间的关系。采用实验与fluEnT计算结合的方法,通过水槽PIV实验得出扩压器内的流场信息,对照不同的湍流模型,得出最佳的计算方案。根据此计算方案计算不同的扩张角下前置扩压器性能的变化,得出各参数之间的规律。结果表明雷诺应力模型能够较好地预测扩压器内部流场;前置扩压器扩张角存在一个最佳值,大于最佳值前置扩压器会出现流动分离;结合理论分析和计算数据总结出计算前置扩压器总压损失系数和静压恢复系数的公式,利用此公式还可求出最佳的前置扩张角和前置扩压器长度,计算误差在5%左右。Diffuser is one key component of the gas turbine combustor following the compressor.Its primary function is to slow down the air flow delivered by the compressor in order to promote efficient combustion and avoid large total pressure losses.An experimental and computational study of cold flow in the dump diffusers was presented.The main aims were to evaluate the influence of pre-diffuser wall angle and pre-diffuser length on the performance of dump diffusers,and to identify the pressure loss mechanisms.PIV experiments were conducted in a simplified test model to help choose of congruent turbulence model.It was observed that apparent flow separation occurred on pre-diffuser wall when pre-diffuser wall angle amplified to certain degree.The pre-diffuser exit flow was distorted,indicating that the uniform exit conditions typically assumed in the diffuser design were violated.Skew distribution of the pre-diffuser outlet flow can result in strong transverse mixing for liquid,the total pressure loss of pre-diffuser increases significantly.The formula of the total pressure loss coefficient and the pressure recovery coefficient was developed.The optimal pre-diffuser length and pre-diffuser wall angle can be conveniently obtained by this equation,the calculation error was less than 5%.中央高校基本业务费(2013121019); 航空基金(20132268003

Alloy Conditions Impact on Al/n~+-Ge Ohmic Contact

gE比SI具有更高的电子和空穴迁移率,且gE材料可以应用于1.3~1.5μM近红外波段,因此gE成为制备微电子和光电子器件的主要材料。然而由于gE的费密能级钉扎效应以及难以获得高浓度的磷(P)原位掺杂,使得n-gE的欧姆接触成为一个难题。采用P+离子注入获得高掺杂浓度的n-gE材料,掺杂浓度为1.5x1019CM-3;依据圆形传输线模型(CTlM)制备了一系列Al/n+-gE样品,研究了不同退火温度和退火方式对其接触特性的影响。实验结果表明,Al/n+-gE样品通过400℃快速热退火(rTA)30 S表现出欧姆接触特性,并且接触电阻率ρC最低,为1.3x10-5Ω·CM2。Germanium is used as the primary material on the micro-or opto-electronic devices,due to the much higher electron and hole mobility compared to Si,as well as its favorable absorption coefficient in the near infrared wavelength regime(1.3-1.5 μm).However,the ohmic contact formation on n-type Ge is still a challenge because of the severe Fermi level pinning effect of n-Ge and the low concentration of P-situ doping.Heavily-doped n-type Ge was achieved with phosphorus concentration of 1.5×1019cm-3 by the ion implantation.And then a series of Al/n+-Ge samples were prepared according to circular transmission line model(CTLM).The samples were annealed at different temperatures and with different annealing ways to analyze the contact characteristics.The test result indicate that the Al/n+-Ge contacts show ohmic characteristics by rapid thermal annealing(RTA) at 400 ℃ for 30 s,with the lowest contact resistivity ρc of 1.3×10-5 Ω·cm2.国家自然科学基金资助项目(61176050;61036003;61176092;60837001); 国家重点基础研究发展计划资助项目(2012CB933503;2013CB632103); 福建省基础研究基金资助项目(2012H0038); 中央高校基本科研基金资助项目(2010121056

GaN LED/metals/Si structure fabricated by bonding and laser-lift off

采用金属键合技术结合激光剥离技术将gAn基lEd从蓝宝石衬底成功转移到SI衬底上。利用X射线光电子谱(XPS)研究不同阻挡层对Au向gAn扩散所起的阻挡作用,确定键合所需的金属过渡层。利用多层金属过渡层,在真空、温度400℃和加压300 n下实现gAn基lEd和SI的键合,通过激光剥离技术将蓝宝石衬底从键合结构上剥离下来,形成gAn基lEd/金属层/SI结构。用金相显微镜及原子力显微镜(AfM)观察结构的表面形貌,测得表面粗糙度(rMS)为12.1 nM。X射线衍射(Xrd)和rAMAn测试结果表明,衬底转移后,gAn基lEd的结构及其晶体质量没有发生明显变化,而且gAn与蓝宝石衬底间的压应力得到了释放,使得SI衬底上gAn基lEd的电致发光(El)波长发生红移现象。The effect of different barrier layers on gold diffusing into GaN is analyzed by X-ray photoelectron spectroscopy(XPS).By using wafer bonding and laser lift-off(LLO),which uses a KrF excimer laser(248 nm) to separate GaN LED from sapphire substrate,an light emitting diode(LED) GaN epi layer is successfully transferred onto a Si substrate at the temperature of 400 ℃.The surface of samples after laser lift-off(LLO) is observed with microscope and atomic force microscope(AFM).The root-mean-square roughness of the transferred GaN LED surface is about 12.1 nm.The X-ray diffraction(XRD) and Raman test results show that the quality of LED on Si substrate has not obviously change,but the electroluminescence peak wavelength of GaN-based LED on Si substrate showes a red shift compared to that on sapphire substrate.国家自然科学基金重点基金资助项目(60837001);福建省自然科学基金资助项目(2008J0221);福建省教育厅科技项目(JB08215

Freestanding palladium nanosheets with plasmonic and catalytic properties

通讯作者地址: Huang, XQ (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 3. Xiamen Univ, Dept Phys, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] metal films can exhibit quantum size and surface effects that give rise to unique physical and chemical properties(1-7). Metal films containing just a few layers of atoms can be fabricated on substrates using deposition techniques(7), but the production of freestanding ultrathin structures remains a significant challenge. Here we report the facile synthesis of freestanding hexagonal palladium nanosheets that are less than 10 atomic layers thick, using carbon monoxide as a surface confining agent. The as-prepared nanosheets are blue in colour and exhibit a well-defined but tunable surface plasmon resonance peak in the near-infrared region. The combination of photothermal stability and biocompatibility makes palladium nanosheets promising candidates for photothermal therapy. The nanosheets also exhibit electrocatalytic activity for the oxidation of formic acid that is 2.5 times greater than that of commercial palladium black catalyst.NSF of China 20925103 20871100 20721001 20703032 MOST of China 2009CB930703 2011CB932403 Fok Ying Tung Education Foundation 121011 NSF of Fujian 2009J06005 Key Scientific Project of Fujian Province 2009HZ0002-

Phenotypic Characterization of Disc1 Deficient Mice

精神分裂症（schizophrenia）是一種多致病因子的精神疾病。從一世紀前被命名至今，許多的研究已經確定了基因的因素與其相關病徵的關連性。Disrupted-in-Schizophrenia 1 (DISC1) 就是其中一種重要的易感性基因。DISC1基因的變異最先是在一個蘇格蘭家族被發現，此家族之許多成員都患有嚴重的精神疾病，然而DISC1變異與其致病的機轉至今仍不清楚。本實驗中，我們使用年齡8至12週之野生型 (wild type，WT)，Disc1基因異型合子 （heterozygote，Het），同型合子（homozygote，Homo) 基因剔除（knockout）雄性小鼠，企圖了解基因缺損在大腦結構與行為上的影響。工作記憶（working memory）在人類是由背外側前額葉皮質（dorsolateral prefrontal cortex，DLPFC）所執行，並且此功能在精神分裂症患者有不良的情況。在小鼠的腦部中執行工作記憶的腦區則被認為是內側前額葉皮質（medial prefrontal cortex，mPFC）。故此，我們分析了三種基因型小鼠的大腦結構與mPFC的第二、三層錐狀神經元之樹突結構。我們發現，Disc1基因變異小鼠的側腦室有增大的情形。利用高基氏染色（Golgi-Cox impregnation），神經樹突結構得以被重構。相較於WT及Het knockout小鼠，Homo knockout小鼠mPFC神經元的樹突分支和複雜程度顯著地減少。並且，在Het knockout以及Homo knockout小鼠，樹突突起（dendritic spine）密度及樹突直徑也都有下降。這些結構上的改變暗示了在mPFC的錐狀神經元接受興奮性傳入的能力可能下降。另外，在mPFC中表現calretinin的細胞數量在Het knockout小鼠也有減少。我們接著利用了許多行為實驗，來觀察這些基因變異小鼠是否出現了類似精神分裂症的行為性狀。Het knockout小鼠的自發活動有稍微下降的情形。除此之外，這些變異小鼠的憂鬱和焦慮程度都沒有發生改變，空間學習以及短期記憶的功能也完整。這些Disc1基因變異小鼠最為顯著的變化是工作記憶的能力。在delayed non-match to place task中，與WT小鼠相比，Disc1基因變異小鼠，需要更久的實驗訓練過程以達到設定的標準。在實驗中，我們則觀察到隨著delayed time延長，Disc1基因變異小鼠之工作記憶能力也會有不良的情況。綜合以上，我們的數據顯示了Disc1基因變異小鼠的mPFC神經元結構以及由mPFC所主導的工作記憶功能都發生改變。這些結構的變化可能會造成大腦皮質神經傳導運作過程的不正常，而導致與精神分裂症相關的症狀出現。Schizophrenia is a multifactorial psychiatric disorder. One century after been so named, researches have confirmed the relation between genetic issues and schizophrenia-related mental illnesses. One of the leading candidate genes is Disrupted-in-Schizophrenia 1 (DISC1). Mutation of DISC1 gene was found in a Scottish family with major mental disorders, however, the mechanisms of DISC1 in pathogenesis of schizophrenia is still unclear. In the present study, in order to investigate the effects of Disc1 deficient on brain structural and function, 8-12 weeks old male wild type (WT), Disc1 heterozygote (Het) and homozygote (Homo) knockout mice were used. In human, working memory function is executed by dorsolateral prefrontal cortex (DLPFC) and is impaired in schizophrenia patients. Its functional equivalent area in mice is the medial prefrontal cortex (mPFC). So we examined the brain structure and dendritic structures of layer II/III pyramidal neurons in mPFC among these three genotypes of mice. The size of lateral ventricle was enlarged in Disc1 mutants. Using Golgi-Cox impregnation, the dendritic structures were therefore reconstructed. Compared to WT and Het knockout mice, the dendritic arborization and complexity of mPFC neurons were significantly reduced in Disc1 Homo knockout mice. The dendritic diameter and density of dendritic spine were also decreased in both Het and Homo group. These structural alterations indicated that the capability of receiving excitatory inputs might decrease in mPFC pyramidal neurons. Besides, calretinin expressing neurons in mPFC of Het knockout mice was also reduced. We then conducted several behavioral tests to investigate if there is schizophrenia like phenotypes in these mutant mice. Slightly reduced locomotor activity was found in Het mice. Besides the unchanged depression and anxiety level, mutant mice also showed intact spatial learning and short term memory. The dramatically altered phenotype in these Disc1 mutant mice was found to be working memory. In delayed non-match to place task, compared with WT littermates, it took longer training process for the mutant mice to master this task, and we also found there was a trend that the mutant mice showed impaired working memory when delayed time was expended. Our data revealed the altered neuronal structure in the mPFC and the impaired mPFC-mediated working memory function in Disc1 mutant mice. These structural changes might lead to impaired cortical transmission processes and schizophrenia-related behavioral deficits

浅析配电网存在问题及配电线路安全运行管理措施

随着社会经济的飞速发展，中国的电网用户数量也在不断地增加，用电需求也呈持续增长状态。为了能够更好地促进配电线路和配电网的安全运行，更好地满足社会用电需求，论文对配电网运行存在的问题进行了简要分析，并对运行管理措施进行了简要探究。</jats:p

10kV 配电网线损问题解决方案的创新研究

随着时代的发展，科技的进步，电成为人们日常生活中不可缺少的部分。在输电时，最为重要的是 10kV 配电网在线损方面的问题。许多的电力单位对 10kV 配电网进行了深入的分析研究，笔者重点讲述配电网线损方面的问题，对其发展前景进行全面的分析。</jats:p

高重复频率皮秒激光烧蚀不锈钢的研究

利用兆赫兹量级高重复频率皮秒激光对304不锈钢进行烧蚀,通过激光共聚焦显微镜和扫描电子显微镜对烧蚀表面进行测量观察。结果表明:单脉冲峰值能量密度和重复频率共同决定不锈钢的烧蚀率,单脉冲峰值能量密度与烧蚀阈值比值越大,烧蚀率越大;在高频低峰值能量密度下能获得更优的表面烧蚀质量。随着扫描速度的提高,烧蚀深度呈对数函数关系逐渐减小,烧蚀后的表面粗糙度先减小后趋于稳定。扫描速度在1.0~1.7 m/s内变化时,烧蚀率变化不大。因此采用交叉扫描路径有利于提高烧蚀后的表面质量

基于电磁感应加热技术的金属线材熔融沉积工艺研究

针对现有金属增材制造成形工艺普遍存在的成形速度慢、粉末材料昂贵以及运行成本高等问题,提出了一种基于电磁感应加热技术的金属线材熔融沉积工艺。利用自主研制的试验系统进行了薄壁圆环结构件沉积成形试验,研究了电磁力对熔滴沉积的作用机理,并结合工艺试验分析了过渡距离对成形件的层间结合性能的影响。试验结果表明:优化感应线圈几何参数,严格控制线材相对感应线圈的位置对该工艺的加工精度与成形质量有重要影响;当喷头至基板间距离处于8~20 mm之间时,成形制件层间结合良好。研究表明,基于感应加热技术的金属线材熔融沉积工艺是一种可行的增材制造新工艺