The compound cylinder and the strength problem

A general discussion is given of the effects of various strength theories on the design of compound cylinders composed of as many as four tubes. Departing from the usual practice in problems of this type, the more modern theories of strength are included.The problem considered is limited to simultaneous, yielding in all component tubes of the cylinder under the action of bore pressure. In addition, new short design procedures employing graphical means are discussed which will considerably reduce the time ordinarily required in such calculations. The methods used are flexible since component tubes of different materials following different strength theories can be treated as easily as cylinders composed of tubes of one material.     

基于构件的软件开发方法及实现

基于构件(Component-Based Software Development,CBSD)的软件系统中的构件可以是COTS(Commercial-Off-the-Shelf)构件,也可以是通过其它途径获得的构件(如自行开发)。CBSD体现了"购买而不是重新构造"的哲学,将软件开发的重点从程序编写转移到了基于已有构件的组装,以便更快地构造系统,减轻用来支持和升级大型系统所需要的维护负担,从而降低软件开发的费用     

Magnetic Field Diffusion Through Infinite Conducting Media

The diffusion of the magnetic field due to a step current in an infinitely long ideal conductor, through infinite media is discussed. An analytical solution of the field diffusion through two concentric cylinders of different conductivity is derived using a generalized Ohm's law which considers both solid and fluid conductors. A rigorous mathematical treatment which can be generalized to any number of conducting cylinders is presented.The limiting case of an external superconducting medium is discussed and it is shown that with all the other parameters fixed it represents a lower limit in diffusion time.     

Experimental study of the critical speed response,of a jeffcott rotor with acceleration

A small, lightly damped rotor (ζ=0.0088) was experimentally tested for a variety of acceleration and deceleration rates. In each case, the amplitude response was plotted as a function of operating speed, with the acceleration rate considered. In each case the results are compared with theoretical predictions. The results agree within 6% at the peak response. The results of the analysis indicate that for high acceleration rates the critical amplitude response may be reduced by a factor of four or more. The frequency of the effective critical speed may be shifted by up to 20%. Furthermore, a beating frequency was observed in the amplitude data after the rotor had passed through the critical speed. This phenomenon is shown to be the vector sum of a synchronous component of amplitude and a nonsynchronous transient component (at the critical speed). The transient nonsynchronous component is shown explicitly via electronic band-pass filtering, as is the forced response component. Finally, spectral analyses were performed over a range of operating speeds, yielding waterfall diagrams and further verification of the existence of the two components.     

LOW DIMENSIONAL GALERKIN METHOD AND ITS ROLE IN QUALITATIVE ANALYSIS OF NONLINEAR BEHAVIOR OF BLUFF BODY WAKES

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆＣＦＤａｉｍｅｄｎｏｔｏｎｌｙａｔｔｈｅｃａｐａｂｉｌｉｔｙｏｆｃｏｍｐｌｅｘｆｌｏｗｃｏｍｐｕｔａｔｉｏｎｓｗｉｔｈｈｉｇｈａｃｃｕｒａｃｙａｎｄｈｉｇｈｅｆｉｃｉｅｎｃｙ,ｂｕｔａｌｓｏａ...     

A robust super-resolution method with improved high-frequency components estimation and aliasing correction capabilities

In this paper, we have proposed a robust super-resolution high-frequency component estimation (RS-HFCE) method, which can efficiently estimate lost high-frequency components and correct aliasing effects of low-frequency components of an image. The fundamental principle of operation of the proposed method is based on the idea that, when a baseband band-limited image signal of known bandwidth in a high-resolution lattice is iteratively low-pass filtered in the frequency domain, the unknown values in the lattice can be interpolated, thus correcting the aliasing for the low-frequency components. If this process is done along with adjusting the amplitudes of the known pixel values, some high-frequency components of an image are automatically extrapolated. In order to provide simultaneous edge preservation and noise removal capabilities of the super-resolved images, an improved version of an adaptive Perona–Malik (PM) model is incorporated into the process. One of the characteristics of the proposed method is its high level of tolerance capabilities to reconstruction errors and noise caused by an increase in the reconstruction scaling factors. High quality images of higher resolution are still appreciably reconstructed when greater magnification factors are used. From a couple of experiments on real images, and using both subjective and objective image quality assessment measures, it is demonstrated that the proposed method outperforms most of other classical methods.     

Mechanical effects of corrosion: an old problem in a new setting

The alloys used for fuel and structural components in nuclear reactors suffer intense bombardment by damaging irradiation. For example, there are components in which every atom may be knocked off its lattice site and replaced by another several times during its lifetime in the core. It is not surprising, therefore, that much of the effort of nuclear metallurgists has been devoted to studying the rather esoteric subject of irradiation damage in metals and alloys. In the event, with thermal nuclear reactors at least, it has been relatively common metallurgical and chemical phenomena, such as thermal creep, fatigue, and corrosion, that have caused the majority of the difficulties.     

论“本格推理”与少年推理小说——以谢鑫作品为例

所谓"本格推理",就是逻辑至上,严格遵循理性的原则。"本格推理"是侦探小说的一个主要派别。"本格"原为日文词,本格派又可称为古典派或传统派。以推理解谜为主要走向,是侦探推理小说的主流。本文以谢鑫创作的"课外侦探组"系列少年侦探小说为例,阐述"本格推理"的表现手法在中国当代少年侦探小说中的运用及其成效。     

A simple approach to mathematical modelling of integer order and fractional order fuzzy PID controllers using one-dimensional input space and their experimental realization

Though over the years, mathematical modelling of fuzzy PID controllers is carried out extensively with two-dimensional and three-dimensional input spaces, the modelling is rarely attempted using one-dimensional input space. In this paper, this gap is reduced by proposing a simple approach where each of the fuzzy P, fuzzy I, and fuzzy D components is modelled using one-dimensional input space and merged to provide the complete PID action. Another speciality of the proposed approach is that it does not require any AND or OR operator for obtaining the mathematical models of individual PID components. To the best of author’s knowledge, such a modelling approach is completely new. This newly introduced idea of modelling is further extended to fractional order fuzzy PID controllers. Applicability of the proposed fuzzy controllers is delineated with four simulation examples and one real-time experimentation case study. To understand the usefulness of the proposed control schemes, performances of the newly obtained controllers are compared with the results available in literature. As the proposed controllers are model-free controllers, they can easily be implemented for other control applications also.     

Models with incomplete correspondence with the prototype

The use of analogies is often advantageous in design and in the prediction of the behavior of complex systems. As developed previously, each component in the model (analog) corresponds to a specific component in the prototype (original system). However, this condition is a consequence of using linear relationships between model and prototype. If the condition of linearity is relaxed, the analog may have components which do not correspond to components in the prototype. Consequently, greater freedom is realized in design of the analog making it possible to overcome conflicting design requirements. Application of the nonlinear prediction equations to a forced vibrating system illustrates the general principles involved.     

On the Classification of the Bonnet Surfaces

In this paper,we will prove that the Bonnet surfaces can beclassified into three different types and the first or second types areequivalent to helicoidal surfaces(including surfaces of revolution andcylinders)under Bonnet deformations.     

多目标进化算法在滤波器优化中的应用

数字滤波器被广泛地关注和使用,已成为通信系统中至关重要的器件之一。针对数字滤波器的要求,利用多目标进化算法对一维数字滤波器进行优化,以期降低其期回波损耗和插入损耗,并证明是可行的。     

聚乙烯链塌缩相变的研究

通过对高分子链构象的完全计数，研究了聚乙烯链的塌缩相变现象．聚乙烯链在金钢石格点上生成，计算中考虑了聚乙烯链的近程相互作用和远程相互作用．结果表明，聚乙烯链在温度下降时，会发生从高温下的伸展状态到低温下的紧缩状态的塌缩现象．对有限长的聚乙烯链，塌缩与链长和吸引势的强度有关，链越长，吸引势越大，塌缩发生的温度就越高，而且我们还发现，聚乙烯链的塌缩相变是一级相变     

Topological phases of quantized light

Topological photonics is an emerging research area that focuses on the topological states of classical light. Here we reveal the topological phases that are intrinsic to the quantum nature of light, i.e. solely related to the quantized Fock states and the inhomogeneous coupling strengths between them. The Hamiltonian of two cavities coupled with a two-level atom is an intrinsic one-dimensional Su-Schriefer-Heeger model of Fock states. By adding another cavity, the Fock-state lattice is extended to two dimensions with a honeycomb structure, where the strain due to the inhomogeneous coupling strengths of the annihilation operator induces a Lifshitz topological phase transition between a semimetal and three band insulators within the lattice. In the semimetallic phase, the strain is equivalent to a pseudomagnetic field, which results in the quantization of the Landau levels and the valley Hall effect. We further construct an inhomogeneous Fock-state Haldane model where the topological phases can be characterized by the topological markers. With d cavities being coupled to the atom, the lattice is extended to d − 1 dimensions without an upper limit. In this study we demonstrate a fundamental distinction between the topological phases in quantum and classical optics and provide a novel platform for studying topological physics in dimensions higher than three.     

基于经验模态分解的中国生态足迹与生态承载力动力学预测

利用mathcad2001和matlab6.5软件,计算了中国1961年～2005年生态足迹和生态承载力,通过经验模态分解（EMD）方法对其进行分析,在此基础上,建立动力学模型对其未来进行预测,希望能通过对中国生态足迹动态研究,建立一个带有周期波动的动力学预测模型,为研究长时间序列的动态变化提供一个全新的研究方法。通过EMD分析后我们可以得到研究要素的不同时间尺度的演化曲线,将这些曲线看成是系统在不同时间尺度下的特解,则可以根据不同时间尺度的EMD分量的曲线够建起对应的动力模型,如趋势项一般对应于指数或线形动力方程,大尺度的周期分量一般可以对应于正弦或与余弦形式的动力方程,最后我们建立一个总的动力预测模型。研究结果表明：随着生态足迹的增大和生态承载力的减小,中国未来20年的生态赤字越来越大,由2006年的-0.932到2025年的-1.632,接近2倍,发展处于不可持续状态。经验模态分解（EMD）方法能很好的分解出生态足迹和生态承载力的波动周期,符合它们的发展规律,并用动力学预测了它们的发展态势,经拟合表明,预测的结果与实际值误差较小。这说明基于EMD的动力学预测模型是科学的。     

基于Web2.0的GIS可重用组件开发模型研究

提出一种基于Web2.0及SOA理念的可重用GIS开发模型,以及基于该开发模型的开发实践。该开发模型将GIS应用开发分为两部分:一是GIS服务及控件的开发,二是基于用户需要的控件搭建开发。这种GIS开发模型能实现更轻量、更开放且可重用的GIS应用。该开发模型的核心价值在于GIS组件的可重用性以及实现终端用户的业务敏捷。     

黄河故道湿地土壤质量因子与景观类型的耦合关系

在湿地生态系统恢复重建过程中,湿地土壤质量变动与景观类型的相互关系及其耦合机制的研究,已成为国内外学者研究的热点问题。本文以豫东黄河故道湿地为研究对象,利用主成分分析、线性回归分析和典型相关分析等方法,研究故道湿地景观类型与土壤质量因子之间的关系,探讨景观类型与土壤生态过程之间的耦合关系。结果显示：①主成分分析（PCA）和典型相关分析（CCA）表明,主成分与湿地景观类型密切相关;主成分P1（土壤有机质与微生物活性）与山杨林地的相关性最大;主成分P2（土壤总磷与容重）与莎草沼泽的相关性最大;主成分P3（土壤pH值）与碱蓬滩地的相关性最大;②土壤性质的改变能够很好地响应湿地景观类型,各景观类型从故堤向外延伸呈顺时针分布在CCA排序轴上,且土壤生态过程与湿地景观类型之间呈现出不同的相关性;③多元回归分析表明,3个主成分与景观类型序列的相关系数为0.955,R²=0.893（F=48.486,p=0.001）,湿地景观类型与土壤质量因子的梯度变化密切相关;湿地土壤生态过程是豫东黄河故道湿地景观类型演变的驱动力之一。     

Force ripple suppression in iron-core permanent magnet linear motors using an adaptive dither

This paper presents the design and realization of an adaptive dither to reduce the force ripple in an iron-core permanent magnet linear motor (PMLM). A composite control structure is used, consisting of three components: a simple feedforward component, a PID feedback component and an adaptive feedforward compensator (AFC). The first two components are designed based on a dominant linear model of the motor. The AFC generates a dither signal with the motivation to eliminate or suppress the inherent force ripple, thus facilitating smooth precise motion while uncompromising on the maximum force achievable. An analysis is given in the paper to show the parameter convergence. Computer simulations and real-time experimental results verify the effectiveness of the proposed scheme for high precision motion trajectory tracking using the PMLM.     

The weighted Condorcet fusion in information retrieval

The Condorcet fusion is a distinctive fusion method and was found useful in information retrieval. Two basic requirements for the Condorcet fusion to improve retrieval effectiveness are: (1) all component systems involved should be more or less equally effective; and (2) each information retrieval system should be developed independently and thus each component result is more or less equally different from the others. These two requirements may not be satisfied in many cases, then weighted Condorcet becomes a good option. However, how to assign weights for the weighted Condorcet has not been investigated.     

Anisotropic fluoride nanocrystals modulated by facet-specific passivation and their disordered surfaces

Rutile-type fluorides have been proven to be active components in the context of emerging antiferr-omagnetic devices. However, controlled synthesis of low-dimensional, in particular two-dimensional (2D), fluorides in a predictable and deterministic manner remains unrealized because of a lack of efficient anisotropic control, which impedes their further development in reduced dimensions. We report here that altered passivation of {110} growing facets can direct the synthesis of rutile-type fluoride nanocrystals into well-defined zero-dimensional (0D) particulates, one-dimensional (1D) rods and 2D sheets in a colloidal approach. The obtained nanocrystals show positive exchange bias and enhanced magnetic transition temperature from the coexistence of long-range antiferromagnetic order and disordered surface spins, making them strong alternatives for flexible magnetic devices and sensors.