基于Van Leer+AUSM混合格式求解三维N-S方程

基于多块粘性结构网格,开展了三维N-S方程数值算法的研究。控制方程的空间离散采用有限体积法,在前人工作的基础上,发展了Van Leer+AUSM混合格式并应用到对流通量的离散中,粘性项采用中心格式离散并利用格林定理计算粘性通量中的导数项,时间推进采用五步R-K法,湍流模型为S-A一方程模型。最后,以M6机翼和某超声速弹丸的粘性流场作为数值算例,计算表明:发展的数值算法对跨声速、超声速流场均具有较高的分辨率,适用于跨、超声速流场的数值模拟。

Impulsive Control for T-S Fuzzy Model Based Chaotic Systems Consisting of Van der Pol Oscillators Coupled to Linear Oscillators

This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators （VDPL） based on their Takagi-Sugeno （T-S） fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality （LMI） is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.

Near-zero Poisson's ratio and suppressed mechanical anisotropy in strained black phosphorene/SnSe van der Waals heterostructure:a first-principles study

Black phosphorene(BP)and its analogs have attracted intensive attention due to their unique puckered structures,anisotropic characteristics,and negative Poisson’s ratio.The van der Waals(vdW)heterostructures assembly by stacking different materials show novel physical properties,however,the parent materials do not possess.In this work,the first-principles calculations are performed to study the mechanical properties of the vdW heterostructure.Interestingly,a near-zero Poisson’s ratio ν_(zx)is found in BP/SnSe heterostructure.In addition,compared with the parent materials BP and SnSe with strong in-plane anisotropic mechanical properties,the BP/SnSe heterostructure shows strongly suppressed anisotropy.The results show that the vdW heterostructure has quite different mechanical properties compared with the parent materials,and provides new opportunities for the mechanical applications of the heterostructures.

Li Hongtao—China’s Van.Gogh

Afamous German art critic oncepraised Chinese artist Li Hongtao as China’s Van.Gogh In March,the critic,also the director of the Ludwigs Germany International Artistic Forum,said:"In a European’s eyes,these paintings are best symbol of complicated art in the world.This kind of art not only implies deep understanding of traditional Chinese art and culture,but also a strong sense of Eurlopean and American art.Such artistic spirit has been expressed athrough the artist’s strong feeling and active desire."

宝马发动机VAN0S召回螺栓更换方法

宝马的VANOS系统是一个由车辆发动机管理系统操纵的液压和机械相结合的凸轮轴控制机构。2015年6月18日,宝马正式召回相关车辆的VANOS单元有松脱甚至断裂危险的螺栓。当螺栓松脱或断裂可能导致VANOS（凸轮轴调节单元）内部密封不严,无法建立油压,使气门正时调节失效。发动机将进入紧急运行模式,同时发动机报警灯点亮（图1）,当螺栓彻底断裂后发动机将停止运转。

从恒速升温速率下的DSC曲线峰温计算含能材料放热分解反应动力学参数的理论和数值方法(英文)

根据Kooij公式和van′t Hoff公式,从恒速升温速率下的DSC曲线峰温导出了计算含能材料放热分解反应动力学参数的两个数学表达式,提出了计算相应动力学参数的数值方法。对1,3,5-三硝基-1,3,5-三氮杂环己酮-2(Keto-RDX),由导出的两个表达式、Kissinger法、Ozawa法、Tang法、Hu-Gao-Zhang法、非线性等转化率积分法(NL-INT)所得的活化能E值彼此接近,表明Kooij′s公式中的a值取0.5,van′t Hoff公式的b值取0.003,可得到合理的动力学参数。

使用Matlab求解Van Der Pol方程的方法研究

以描述振荡器的经典的范得波(Var der Pol)微分方程的求解为例,给出了三种求解微分方程数值解的方法,分别是:应用仿真方框图求解;Matlab函数求解;使用S函数求解,并对使用三种方法求解微分方程进行了比较。

一类三维混沌系统的T—S模糊控制

针对一类三维混沌系统，在用T—S模糊模型重构该系统的基础上，利用反馈控制思想和并行分布补偿（PDC）技术，基于Lyapunov理论为该系统设计了状态反馈控制器．利用线性矩阵不等式（LMI）可求出模糊控制器的参数，实现以衰减率a全局渐近稳定．对该系统的一个重要特例—ADVP系统的仿真结果验证了该控制方法的有效性．

Van Der Corput不等式推广的改进

将Van Der Corput不等式的推广做了进一步改进,建立了Van Der Corput不等式更强的推广式,它优于现有的相关结论。

Van.Beek功能矫治器治疗安氏Ⅱ’类早期骨性错的研究

目的 ,对 Van.Beek功能矫正器治疗安氏 类早期骨性错的效果进行观察。方法 :应用 Van.Beek功能矫正器对 12名 10 - 12岁安氏 类骨性错患者进行治疗 ,以 X线头影测量分析方法评价疗效。结果 :上下颌骨矢状不调减小 ,Van.Beek功能矫正器能在水平方向产生抑制上颌骨生长 ,刺激下颌骨生长 ;在垂直方向控制上下颌骨后下旋转 ,压低上下前牙及伸长下磨牙的效果。结果 :Van.Beek功能矫正器治疗安氏 类早期骨性错 ,可产生显著的生长改良作用。

Context Model in Chinese and American Reports on Yangtze Sunken Ship

Two pieces of news reports on Yangtze Sunken Ship event are analyzed in this essay to prove the influence of context model in news reports discourse by comparative analysis approach. Through illustrating the different expressions in these reports discourse, the process how cognition(or context model) influences and determines the production and understanding of discourse has been demonstrated.

The 600 keV electron injections in the Earth's outer radiation belt:A statistical study

Relativistic electron injections are one of the mechanisms of relativistic(≥0.5 MeV) electron enhancements in the Earth’s outer radiation belt. In this study, we present a statistical observation of 600 keV electron injections in the outer radiation belt by using data from the Van Allen Probes. On the basis of the characteristics of different injections, 600 keV electron injections in the outer radiation belt were divided into pulsed electron injections and nonpulsed electron injections. The 600 keV electron injections were observed at 4.5 < L <6.4 under the geomagnetic conditions of 450 nT < AE < 1,450 nT. An L of ~4.5 is an inward limit for 600 keV electron injections. Before the electron injections, a flux negative L shell gradient for ≤0.6 MeV electrons or low electron fluxes in the injected region were observed. For600 keV electron injections at different L shells, the source populations from the Earth’s plasma sheet were different. For 600 keV electron injections at higher L shells, the source populations were higher energy electrons(~200 keV at X ~–9 R_(E)), whereas the source populations for 600 keV electron injections at lower L shells were lower energy electrons(~80 keV at X ~–9 R_(E)). These results are important to further our understanding of electron injections and rapid enhancements of 600 keV electrons in the Earth’s outer radiation belt.

Azo-Dye Doped Polymers as an Universal Light Polarization Sensitive Photo Material

The properties of the polarization sensitized material with the wide possibilities,on the basis of azo-dye doped polymers,are reviewed and analyzed shortly.Some experimental results obtained on these materials in the polarization holography andphotography on the basis of Weigert’s effect are briefly described.In particular,with the help of these materials,the results ofholographic recording and reconstruction of the polarization characteristics of the light field have been significantly improved.Wereobtained holographic diffractive optical elements with the highest diffraction efficiency,such as diffraction gratings and zone plates(Fresnel lenses),which have no analogues among the known ones.Was observed self-recording phenomenon in a dynamicholographic recording and recovery process.The prospects of using the given materials in the photography for obtaining polarimetricimages of various objects,including celestial bodies,were shown.

Hysteresis of saturation-capillary pressure relations under consecutive drainage-imbibition cycles in fine sandy medium

The hysteresis of saturation-capillary pressure(S-p) relations was investigated in a fine sandy medium under consecutive drainage-imbibition cycles,which resulted from scheduled water level fluctuations.A drainage-imbibition cycle starts with a drainage process and ends with an imbibition process in sequence.The saturation and capillary pressure were measured online with time domain reflectometry(TDR) probes and T5 tensiometers,respectively.Results show that the relation between the degree of hysteresis and the number of the drainage-imbibition cycles is not obvious.However,the degree decreases with the increase of the initial water saturation of the imbibition processes in these drainage-imbibition cycles.The air-entry pressure of a sandy medium is also found to be constant,which is independent of the drainage-imbibition cycles and the initial water saturation of the drainage process.In all the imbibition processes,parameter α of the van Genuchten(VG) model decreases with the increase of the initial water saturation,which corresponds positively to the magnitude of the hysteresis.

Rotating Squeezed Vacua as Time Machines

Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level.

改进视觉注意力网络的水下目标检测算法

针对传统水下图像检测方式易受水中光线、复杂环境的影响,造成水下目标识别精度不高,泛化性较差的问题,提出了一种改进YOLOv5s的水下目标检测算法。首先引入了Double MSRCR算法,解决了水下物体清晰度低,特征模糊的问题。在网络结构方面,主干网络引入C_VAN模块,提升了神经网络特征提取能力;其次在颈部网络中,引入RFB_S感受野,增强神经网络的多尺度适应能力;最后引入NAMAttention空间与通道注意力机制,增强网络上下文特征的表达能力。所提方法相较于Faster-RCNN检测精确度提高了6.5%,相较于YOLOv4检测精确度提高了4.1%,相较于YOLOv5s检测精确度提高2.7%,检测速度提升了56.34 fps,证明了方法适用于实时水下检测任务。

梅花鹿颈背部异常松弛皮肤光镜组织学观察

本研究利用Weigert’s-Van Giesson染色法和Masson氏三色染色法分别对正常梅花鹿和颈背部皮肤异常松弛的梅花鹿皮肤中的弹性纤维和胶原纤维进行观察研究,探讨梅花鹿松弛皮肤组织学致病特点。结果表明,正常梅花鹿真皮网状层中有较多的弹性纤维有规律地平行排列,呈波浪状,染色均匀;真皮乳头层有少量弹性纤维垂直于表皮分布。皮肤松弛梅花鹿或是真皮乳头层中缺乏弹性纤维(大0号和79号鹿),或是网状真皮层中弹性纤维严重发育不全,出现集聚、断裂现象(33号和79号),且排列紊乱、呈不规则状(大0号);正常梅花鹿皮肤胶原纤维在真皮层中呈多层规律性分布。皮肤松弛梅花鹿胶原纤维束比正常胶原束粗大、胶原纤维束减少、堆积、排列杂乱无序,胶原纤维间表现为严重的稀疏。这些现象与人类皮肤松弛症的皮肤组织学症状非常相似。

基于新α表达式的实用PT方程

提出了范德华型方程中引力项参数α的一种新的实用表达式，给出了基于新α表达式的ＰＴ方程。３０种物质饱和蒸汽压及饱和液体密度同时关联的结果表明，修正的ＰＴ方程较原始的有较大改进，特别是对极性物质。还给出了普遍化的ＰＴ方程，其对极性物质及非极性物质都有较高的预测精度。

范德瓦耳斯气液状态方程纵横谈

首先强调了范氏方程是气液系统的状态方程,范氏方程可以很好地说明物质气态和液态的相互转变.分析了焦-汤效应,简述了气体的液化与低温的获得.

基于Motorola GM950I的转播车通话系统拓展

介绍了苏州广电总台在5讯道高清转播车上使用Motorola GM950I拓展通话系统的案例,将转播车上Clear-Com的MS-704有线通话与手持式无线对讲机Motorola SMP318联通。从硬件和软件改造两方面入手,从原理上介绍了将两个GM950I组建成车载台接入转播车通话系统,提高通话系统的灵活性,提升节目制作效率。