高超声速升力体气动力气动热数值计算

升力体气动布局，由于其良好的高超声速气动特性、有效的内部空间和有益的防热特性，越来越受到气动工作者的重视，该文应用张涵信院士的NND格式思想，用数值模拟的方法对类似于美国X-33的升力体外形进行了气动力、气动热研究。特别是在粘性项的离散和表面热流率的计算中应用了散度和梯度的积分定义，避免了数值计算的奇异性，保证了通量守恒，提高了计算效率。结果表明气动热计算结果与美国同类飞行器结果接近，驻点热流率与经典理论结果一致

A New Genus Record of Phyllobothriidae from Marine Fish Dasyatis akajei in China

报道检获于厦门海域赤魟(Dasyatis akajei)肠道中的四叶目叶槽科蔷薇属叶枕蔷薇线虫Rhodobothriumpulvinatum Linton 1889,经鉴定比较,为我国鱼类绦虫属的新记录。本次共剖检赤魟46尾,阳性2尾,感染率为4.3％,感染强度为5～7条/尾,并对所获虫体进行了描述。Rhodobothrium pulvinatum, one species of Phyllobothriidae (Cestoda: Tetraphyllidea) from marine fish Dasyatis akajei in Xiamen, Fujian, China was reported. The genus Rhodobothrium Linton, 1889 was erected for R. pulvinatum from the intestine of Dasyatis kuhli. which was new genus record in China, Dasyatis akajei was also a new record of host. 46 of Dasyatis akajei were examined, 2 of which were infected with cestode, the infective rate was 4. 3%, the infective intensity of the cestode was 5-7, the description of the worm is provided in the present paper.厦门大学校级自选课题资助(2002

Unsteady Aerodynamic Modeling Based on POD-ARX

The lack of stability is a problem encountered when applying the classical POD-Galerkin method to problems of unsteady compressible flows around a moving structure. To solve this problem, a hybrid reduced-order model named POD-ARX is constructed in this paper. The construction of this model involves two steps, including first extracting the fluid modes with the POD technique and then identifying the modal coefficients with the ARX model. The POD modes with the block of all modified primitive variables are extracted from the system response to the training signal. Once the POD modes are obtained, the snapshots are projected on these modes to determine the time history of modal coefficients and the resulting modal coefficients are used to identify the parameters of ARX model. Then, the ARX model is used to predict the modal coefficients of the system response to the validation signal. Sample two-dimensional aerodynamic force calculations are conducted to demonstrate this method. Results show that this method can produce a stable and accurate prediction to the aerodynamic response with significant improvement of computational efficiency for linear and even some nonlinear aerodynamic problems. In addition, this method also shows good wide-band characteristics by using the &quot;3211&quot; multistep signal as the training signal.</p

早熟优质籼稻三系不育系伍天A的选育

【目的】选育早熟优质三系不育系,为优质稻新品种选育奠定基础。【方法】2007年早季以泉5B/天丰B的F4代为父本,与不育系泉5A测交,经过多代回交和多年观察筛选,选育早熟优质三系不育系新品种。【结果】选育出的早熟优质不育系伍天A,于2019年通过福建省农作物品种审定委员会审定(闽审稻20190047),表现育性稳定,不育株率100%,不育度99.99%;异交率高,柱头总外露率64.77%;米质优,稻米的主要品质指标:整精米率66.0%、粒长6.7 mm、长宽比3.4、垩白粒率4%、垩白度0.6%、透明度1级、碱消值7.0级、胶稠度50 mm、直链淀粉含量23.8%,其中整精米率、垩白度、透明度、碱消值均达到NY/T593-2013《食用稻品种品质》一等食用籼稻品种品质标准,但胶稠度、直链淀粉含量等指标还不够理想,需在保持其优质早熟等优良特性的基础上,对品质性状进行改造提升;早熟,播始历期均在66 d左右,与天丰A相同;配合力强,伍天A与R713配组育成的三系稻新组合——伍天A/R713于2019年通过福建省农作物品种审定委员会审定(闽审稻20190035)。【结论】伍天A是一个育性稳定、异交率高、米质优、早熟、配合力强的三系不育系,可以配制出优质、多种熟期的三系杂交水稻新组合

the application of backtracking algorithm in multi- constraint assignment problem

以学生宿舍合理分配问题为背景,对分配中所涉及的学生高考入学成绩、生源地、宿舍类别等诸多约束条件进行充分分析和探讨,给出了解决这类问题的一种新的有效算法--基于矩阵存储的回溯算法,并给出了算法的实现细节.在此基础上,讨论了该算法的时间复杂度,得出了该算法较同类问题的回溯法具有更好的时间效率,说明了该算法在多约束分配问题中更具合理性和有效性

基于矩阵存储的学生分班问题的回溯算法

结合项目开发,提出了多约束条件下合理分配问题的一种解法&mdash;&mdash;基于矩阵存储的回溯算法。以学生合理分班问题为例,以学生成绩和男女生比例等诸多条件作为约束,给出了算法的具体实现过程,分析了算法的时间复杂度。该算法较同类问题的回溯法,效率有很大提高,实际应用的结果表明了算法的合理性和有效性

four-tier structure based on .net and its application in integrated information system

阐述应用程序开发的三层结构的基本组织形式及存在的问题,提出了基于四层结构的应用程序开发模型及其带来的好处.结合七里村采油厂综合信息系统开发实例,对基于.NET的四层结构的应用程序开发技术进行了研究,实现了基于.NET的四层结构的部署,阐述了基于四层结构的具体实现策略,并在此基础上给出了基于四层结构的应用程序设计与开发的关键技术

design and realization of four-tier structure and application based on asp.net

阐述软件设计开发的四层结构的组织形式及其关键技术,提出了一种基于.NET的四层结构应用模型:显示层、业务逻辑层、数据访问层以及数据库,逻辑层次清晰、耦合度低.结合研究生综合信息系统应用实例,实现了基于.NET的四层结构的部署.和三层结构相比,负载能降低24.32%

乘波体荷兰滚模态特性研究

乘波体非轴对称、扁平、大长细比的几何外形特点决定了其存在严重的横航向耦合动稳定性问题。目前对乘波体横航向稳定性的研究还相对较少,且一般只针对单一外形,对飞行器设计未能获得有指导意义的定性、定量结论。以幂次乘波体为研究对象,首先引入设计参数kw和φ描述其外形特点,然后结合CFD数值模拟和Kriging代理模型,获得了整个设计参数空间内乘波体的静/动导数,进而通过求解飞行动力学耦合方程特征根获得乘波体的横航向耦合动稳定荷兰滚模态特性。定义了荷兰滚动稳定性导数的概念,推导了荷兰滚阻尼近似表达式,解释了不同攻角下荷兰滚模态发散/收敛的成因,获得了荷兰滚阻尼随设计参数和攻角的分布规律。推导了荷兰滚频率近似表达式,获得了荷兰滚频率随设计参数和攻角的分布规律