一种连续波多站发射机及频谱分析

介绍了一种连续波多站发射机的新方案，从理论上对该机的发射频谱进行了分析，并与实际结果进行比较。理论和实际都证明该方案具有很好的交调抑制、谐波抑制和杂波抑制、相噪低等诸多优点。     

Local artificial boundary conditions for Schrödinger and heat equations by using high-order azimuth derivatives on circular artificial boundary

The aim of the paper is to design high-order artificial boundary conditions for the Schrödinger equation on unbounded domains in parallel with a treatment of the heat equation. We first introduce a circular artificial boundary to divide the unbounded definition domain into a bounded computational domain and an unbounded exterior domain. On the exterior domain, the Laplace transformation in time and Fourier series in space are applied to achieve the relation of special functions. Then the rational functions are used to approximate the relation of the special functions. Applying the inverse Laplace transformation to a series of simple rational function, we finally obtain the corresponding high-order artificial boundary conditions, where a sequence of auxiliary variables are utilized to avoid the high-order derivatives in respect to time and space. Furthermore, the finite difference method is formulated to discretize the reduced initial–boundary value problem with high-order artificial boundary conditions on a bounded computational domain. Numerical experiments are presented to illustrate the performance of our method.     

Development of a noise prediction software NASEFA and its application in medium-to-high frequency ranges

For the analysis of noise problems in medium-to-high frequency ranges, the energy flow boundary element method (EFBEM) has been studied. EFBEM is numerical analysis method of energy flow analysis (EFA), and solves energy governing equations using a boundary element method in complex structures. Based on EFBEM, a noise prediction software, “noise analysis system by energy flow analysis” (NASEFA), was developed. For effective maintenance, NASEFA is composed of three main modules: the translator, the model converter, and the main solver. The translator changes the FE model to the NASEFA BE model, and the model converter changes the BE model to an EFBE model, including various data, such as structural materials, medium properties, sources, and boundary conditions. NASEFA then solves the acoustic energy density and intensity on boundary and in the field. Moreover, it analyzes interior and exterior noise problems for single and multiple domains in two and three dimensions. Finally, for the validation of the software developed, interior and exterior noise predictions of various structures were performed. The results obtained with NASEFA were compared with those of the commercial SEA program and experiment. From these comparative studies, the usefulness of NASEFA was established.     

电磁轨道炮外弹道建模与仿真研究

针对电磁轨道炮在发射时存在初始扰动,飞行时由于速度极大引起气动烧蚀改变气动外形,因此有必要建立电磁轨道炮外弹道数学模型,分析其外弹道特性.通过分析了电磁轨道炮外弹道建模方法,建立了电磁轨道炮的外弹道数学模型.根据不同技战术指标建立初始随机概率模型,用Monte Carlo方法对电磁轨道炮的外弹道特性进行仿真.仿真结果给出了一定散布范围内的高低概率误差和方向概率误差,对电磁轨道炮武器系统设计指标的提出有参考价值.     

Connected sum of digital closed surfaces

During the past 20 years the research of digital surfaces has proceeded to find their properties in the digital space Zⁿ, such as a topological number, a simple k-point, the 3D-Jordan theorem, a k-separating set, a boundary detecting algorithm and so on. Actually, unlike surfaces in a continuous space, the features of digital surfaces have different characteristics. The aim of this paper is to introduce the notion of a digital closed k-surface in Zⁿ, n ? 3, with the general k-adjacency relations as a generalization of Malgouyres’ and Morgenthaler’s k-surfaces in Z³, to establish some minimal simple closed k-surfaces in Z³ and to find their digital topological properties in relation with the k-fundamental group and k-contractibility. Moreover, a connected sum of two digital closed surfaces is introduced and its digital topological properties are investigated.     

Reconstruction from Projections Using Grassmann Tensors

In this paper a general procedure is given for reconstruction of a set of feature points in an arbitrary dimensional projective space from their projections into lower dimensional spaces. This extends the methods applied in the well-studied problem of reconstruction of scene points in ℘³ given their projections in a set of images. In this case, the bifocal, trifocal and quadrifocal tensors are used to carry out this computation. It is shown that similar methods will apply in a much more general context, and hence may be applied to projections from ℘ ⁿ to ℘ ^m , which have been used in the analysis of dynamic scenes, and in radial distortion correction. For sufficiently many generic projections, reconstruction of the scene is shown to be unique up to projectivity, except in the case of projections onto one-dimensional image spaces (lines), in which case there are two solutions. Projections from ℘ ⁿ to ℘² have been considered by Wolf and Shashua (in International Journal of Computer Vision 48(1): 53–67, 2002), where they were applied to several different problems in dynamic scene analysis. They analyzed these projections using tensors, but no general way of defining such tensors, and computing the projections was given. This paper settles the general problem, showing that tensor definition and retrieval of the projections is always possible.     

非致命防暴弹外弹道仿真

研究防暴弹外弹道性能优化设计问题,现有的防暴弹外弹道模型缺乏准确性,为提高准确性,提出合理假设和简化处理,改进原有榴弹低速低伸外弹道模型,建立更适合于防暴弹的外弹道模型;利用SIMULINK仿真工具对38mm防暴弹两种设计方案进行外弹道仿真,并将仿真结果与实弹测试进行对比分析,从而选择具有射程远符合设计指标的方案.结果表明:改进优化后的外弹道模型对一般防暴弹具有普遍适应性,为防暴弹设计阶段不同方案的选择提供参考.     

一维弹道修正弹射程修正能力计算方法

随着智能弹药的发展,一维弹道修正弹在提高射击精度方面的效果日益受到关注.为了计算一维弹道修正弹的射程修正能力,采用计算流体力学方法仿真得到其阻力参数;采用Logistic曲线,利用计算出的阻力系数,拟合出了修正状态下弹丸的阻力曲线;最后,采用四阶龙格-库塔法求解质点弹道微分方程,并详细分析了弹道修正能力.以某口径一维弹道修正弹为例,求解结果表明,所采用的方案可以有效快速地计算出一维弹道修正弹丸的射程修正能力.     

异形台阶孔件的成形工艺与数值模拟

冷成型工艺多用于实体件和套筒件的加工,对于具有台阶孔的零件,在生产领域应用极少。EPB传动螺母是一个异形台阶孔件,其台阶小孔与大孔值差较小,且外部成形端在大孔端,成形工艺较为复杂。根据经验,利用三维软件设计加工工艺,并利用冷成型分析软件Deform-3D进行数值模拟,分析其可行性。     

挤塑聚苯乙烯泡沫板外墙外保温系统施工要点及体会

文章以南京理工大学“十五”三期教工集资住宅为例,介绍了挤塑聚苯乙烯泡沫板（FWB）外墙外保温系统的施工工艺和质量控制要点,以及在施工实践中的一些体会。