基于等离子体合成射流的飞翼布局模型主动流动控制风洞实验研究

为探究等离子体合成射流对三维模型的流动控制效果和机理,在中等展弦比飞翼布局模型前缘布置等离子体合成射流激励器开展低速风洞实验研究。通过六分量天平测力,考察沿弦向、展向不同分布位置的等离子体合成射流对飞翼模型气动力和气动力矩的作用;采用PIV(Particle Image Velocimetry,粒子图像测速)测量模型表面流场分布,研究等离子体合成射流流动控制机理。结果表明:在飞翼模型单侧布置等离子体合成射流,能够有效改善其气动特性,并能产生附加的滚转力矩,滚转力矩系数变化量最高达到0.009;在飞翼模型左右弦布置等离子体合成射流,能显著增强飞翼模型横向稳定性,滚转力矩系数波动范围减小66.7%。沿弦向,等离子体合成射流位置离前缘越近,控制效果越好,距前缘0mm的激励器控制效果最好;沿展向,布置的等离子体合成射流越多,对模型的升力特性改善作用越明显,布置方式以均布为优。在失速迎角前后,等离子体合成射流的流动控制机理不同:在小迎角下,等离子体合成射流在前缘起到了使转捩提前的作用;在失速迎角附近,则加速了分离区的流动、减小了分离区厚度。国家自然科学基金项目(51707169)中航工业创新基金产学研项目(cxy2013XD28)福建自然科学基金项目(2019J01042)厦门大学校长基金项目(20720170057

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中药是我国传统医学的重要组成部分,但部分中药存在成分复杂、水溶性差等问题,给临床前研究,尤其是体外药效学研究带来困扰。本文就目前体外药效学研究中难溶性中药或中药成分增溶方法或技术进行综述,探讨其可行性及对中药药效行为的影响。福建省自然科学基金项目（2015J01491

Experimental Study on Accelerating the Gas Flow Induced by Planar Coil Electromagnetic Coupling Surface DBD Gas Discharge

为了提高典型沿面dbd平板激励器诱导气流速度,通过实验研究了典型dbd平板激励器表面的磁场分布,提出了在dbd平板激励器的上、下电极之间夹进平面线圈,运用电磁耦合原理增强等离子体激励器放电效果,从而加速dbd等离子体诱导气流的方法。探究了不同结构参数的电感线圈产生的电磁耦合作用对大气压下平板式dbd等离子体激励器放电加强的效果,以及夹进平面线圈后加载电源的电压和频率对dbd放电的影响,并利用粒子图像测速技术测量了电磁耦合作用下典型dbd等离子体诱导气流流场,考察了其中电磁耦合对加速诱导气流的作用。实验结果表明,运用电磁耦合作用可在一定程度上增强等离子体激励器的放电效果,一些电感线圈产生的电磁耦合作用可显著改善dbd等离子体诱导气流的连续性和加厚流场区域。To accelerate the flow induced by typical surface DBD actuator, we studied the magnetic distribution on the surface of a typical DBD actuator qualitatively through experiments.We proposed a method that inductance coils between the upper electrode and the lower electrode were installed to enhance the discharge and increase the flow speed due to the electromagnetic coupling applied to the plasma actuator.Inductance coils with different structure parameters which could create various electromagnetic coupling impacts were used to improve the DBD plasma discharge.Furthermore, we measured the induced flow charts of DBD plasma actuators with electromagnetic coupling using the particle image velocimetry to study the electromagnetic coupling impact on increasing the flow speed induced by DBD plasma.The results show that, by applying electromagnetic coupling to the typical DBD plasma actuator, its discharge can be improved and the airflow induced by the plasma can be accelerated by some kinds of inductance coils, improving the induced flow in both continuity and thickness.福建省自然科学基金(2010J01014)~

大鸨越冬栖息地选择

2003～2006年的1～2月在吉林省镇赉县和内蒙古兴安盟科尔沁右翼前旗接合部的草原地带,对大鸨越冬栖息地的选择进行了考察研究,并将栖息区域人为地划分为3种类型。一是农田荒地和周边草甸,二是平均低于40cm的矮针茅草原,三是平均高于40cm的高针茅草原。结果表明,大鸨对这3种栖息地类型选择明显。农田生境植物性食物丰富,草原生境动物性食物较多

differential fault analysis on piccolo

Piccolo算法是CHES 2011上提出的一个轻量级分组密码算法,它的分组长度为64-bit,密钥长度为80/128-bit,对应迭代轮数为25/31轮.Piccolo算法采用一种广义Feistel结构的变种,轮变换包括轮函数S-P-S和轮置换RP,能够较好地抵抗差分分析、线性分析等传统密码攻击方法.该文将Piccolo算法的S-P-S函数视为超级S盒(Super Sbox),采用面向半字节的随机故障模型,提出了一种针对Piccolo-80算法的差分故障分析方法.理论分析和实验结果表明:通过在算法第24轮输入的第1个和第3个寄存器各诱导1次随机半字节故障,能够将Piccolo-80算法的密钥空间缩小至约22-bit.因此,为安全使用Piccolo算法,在其实现时必须做一定的防护措施.国家自然科学基金(61103192,61070215)|信息安全国家重点实验室开放基金(01-02-5)资

吸力式基础离心模型试验的动力加载设备

离心模型试验是进行海洋工程研究的一种新型技术,具有广泛的应用前景。本文主要介绍了清华大学研制开发的电磁式激振器,该激振器用于吸力式基础离心模型试验中对模型施加水平动荷载。该激振器最大的技术难点是在100g(g为重力加速度)离心加速度下,对吸力式桶基施加高频率的循环荷载

A Dynamic Loading Device for Suction Pile in Centrifuge

离心模型试验是进行海洋工程研究的一种新型技术，具有广泛的应用前景。主要介绍了清华大学研制开发的电磁式激振器，该激振器用于吸力式基础离心模型试验中对模型施加水平动荷载。该激振器最大的技术难点是在100g(g为重力加速度）离心加速度下，对吸力式桶基施加高频率的循环荷载。 Centrifuge modelling is a new technology and potential useful tool in the investigation of offshore structures. This paper describes an electromagnetic actuator that has been designed to apply cyclic horizontal loading on piles in centrifuge. With this d

The degradation of DDTs by Burkholderia xenovorans LB400 biphenyl dioxygenase and mutants

Dicholodiphenyltrichloroethanes (DDTs)is probably the best known and typical persistent organic pollutant in the world, which has been widely used in malaria control and agricultural deworming.They are still detected in various environmental matrices and has new input sources although their usage in agriculture has been banned in China and others.Numerous concerns have arisen over the past decades about the adverse environmental impacts(including harm to offshore ecosystem and human health)of DDTs.There has been a considerable interest over the last decades for the Rieske-type arylhydroxylating dioxygenases (RHDs)as they are seen as potentially capable of initiating their degradation.[Objective] In order to explore the degradation characteristics and mechanism of biphenyl dioxygenase(BPDO)on DDTs, we selected Burkholderia xenovorans LB400 biphenyl dioxygenase and its mutants to explore the degradation process of p,p'-DDT and o,p'-DDT.[Methods] Using BphAE_(LB400) as parent, the mutant BphAE_(S283M) was obtained by two-step site-directed mutagenesis from Ser to Met.The degradation characteristics and mechanism of wild type and mutant were explored by comparing the catalytic performance of wild type and mutant to DDTs, simulating the structure of mutant protein and molecular docking.[Results] The data showed that BphAE_(LB400) and BphAE_(S283M) could not be degraded p,p'-DDT, but BphAE_(S283M) metabolized o,p'-DDT and produced two stereoisomers.The structural analysis of BphAE_(LB400) and BphAE_(S283M) showed that the reaction ring of p,p'-DDT did not coincide with the biphenyl reaction ring in the original crystal structure.In the o,p'-DDT-BphAE_(S283M) conformation, the proximal ring did not fit the biphenyl reactive ring as well, but its orientation toward the catalytic Fe~(2+) places two vicinal atoms at a distance(within 0.5 nm)that would allow a catalytic reaction.In addition, the surface area and volume of the catalytic cavity of BphAE_(S283M) is larger than that of BphAE_(LB400), which is likely to contribute to the combination of BphAE_(S283M) and o,p'-DDT.[Conclusion] 283 is the key amino acid residue that affects the catalytic metabolism of BPDO to DDTs.It can affect the substrate specificity by adjusting the distance between the reaction carbon atom and the catalytic center and the size of the catalytic cavity.This will provide better insights about the bases for BPDO broad substrate range and about the mechanisms by which the enzyme evolves to change or expand its substrate range and its stereo-and regiospecificity