Band structure calculation of scalar waves in two-dimensional phononic crystals based on generalized multipole technique

A multiple monopole （or multipole） method based on the generalized mul- tipole technique （GMT） is proposed to calculate the band structures of scalar waves in two-dimensional phononic crystals which are composed of arbitrarily shaped cylinders embedded in a host medium. In order to find the eigenvalues of the problem, besides the sources used to expand the wave field, an extra monopole source is introduced which acts as the external excitation. By varying the frequency of the excitation, the eigenvalues can be localized as the extreme points of an appropriately chosen function. By sweeping the frequency range of interest and sweeping the boundary of the irreducible first Brillouin zone, the band structure is obtained. Some numerical examples are presented to validate the proposed method.

Exact solution of the (1+2)-dimensional generalized Kemmer oscillator in the cosmic string background with the magnetic field

We study a two-dimensional generalized Kemmer oscillator in the cosmic string spacetime with the magnetic field to better understand the contribution from gravitational field caused by topology defects,and present the exact solutions to the generalized Kemmer equation in the cosmic string with the Morse potential and Coulomb-liked potential through using the Nikiforov-Uvarov(NU)method and biconfluent Heun equation method,respectively.Our results give the topological defect’s correction for the wave function,energy spectrum and motion equation,and show that the energy levels of the generalized Kemmer oscillator rely on the angular deficitαconnected with the linear mass density m of the cosmic string and characterized the metric’s structure in the cosmic string spacetime.

An Overview of the Multi-Band and the Generalized BCS Equations-Based Approaches to Deal with Hetero-Structured Superconductors

We trace the conceptual basis of the Multi-Band Approach (MBA) and recall the reasons for its wide following for composite superconductors (SCs). Attention is then drawn to a feature that MBA ignores: the possibility that electrons in such an SC may also be bound via simultaneous exchanges of quanta with more than one ion-species—a lacuna which is addressed by the Generalized BCS Equations (GBCSEs). Based on several papers, we give a concise account of how this approach: 1) despite employing a single band, meets the criteria satisfied by MBA because a) GBCSEs are derived from a temperature-incorporated Bethe-Salpeter Equation the kernel of which is taken to be a “superpropagator” for a composite SC-each ion-species of which is distinguished by its own Debye temperature and interaction parameter and b) the band overlapping the Fermi surface is allowed to be of variable width. GBCSEs so-obtained reduce to the usual equations for the Tc and Δ of an elemental SC in the limit superpropagator → 1-phonon propagator;2) accommodates moving Cooper pairs and thereby extends the scope of the original BCS theory which restricts the Hamiltonian at the outset to terms that correspond to pairs having zero centre-of-mass momentum. One can now derive an equation for the critical current density (j0) of a composite SC at T = 0 in terms of the Debye temperatures of its ions and their interaction parameters— parameters that also determine its Tc and Δs;3) transforms the problem of optimizing j0 of a composite SC, and hence its Tc, into a problem of chemical engineering;4) provides a common canopy for most composite SCs, including those that are usually regarded as outside the purview of the BCS theory and have therefore been called “exceptional”, e.g., the heavy-fermion SCs;5) incorporates s±-wave superconductivity as an in-built feature and can therefore deal with the iron-based SCs, and 6) leads to presumably verifiable predictions for the values of some relevant parameters, e.g., the effective mass of electrons, for the SCs for which it has been employed.

Entropy of a rotating and charged black string to all orders in the Planck length

By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein-Hawking entropy and its correction term on the background of a rotating and charged black string. Here, the quantum field is entangled with quantum states in the black string and thin film to the event horizon from outside the rotating and charged black string. Taking into account the effect of the generalized uncertainty principle on quantum state density, it removes the difficulty of the divergence of state density near the event horizon in the brick-wall model. These calculations and discussions imply that high density quantum states near the event horizon of a black string are strongly correlated with the quantum states in a black string and that black string entropy is a quantum effect. The ultraviolet cut-off in the brick-wall model is not reasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the viewpoint of quantum statistical mechanics, the correction value of Bekenstein-Hawking entropy is obtained. This allows the fundamental recognition of the correction value of black string entropy at nonspherical coordinates.

Discovering Crustal Deformation Bands by Processing Regional Gravity Field

Objectives： This article presents a new computational procedure to discover scratches buried in the earth＇s crust. We also validate this new interdisciplinary analysis method with regional gravity data located in a well-known Dabie orogenic zone for test. Methods： Based on the scratch analysis method evolved with mathematical morphology of surfaces, we present a procedure that extracts information of the crustal scratches from regional gravity data. Because the crustal scratches are positively and highly correlated to crustal deformation bands, it can be used for delineation of the crustal deformation belts. The scratches can be quantitatively characterized by calculation of the ridge coefficient function, whose high value traces delineate the deformation bands hidden in the regional gravity field. In addition, because the degree of crustal deformation is an important indicator of tectonic unit divisions, so the crust can be further divided according to the degree of crustal deformation into some tectonic units by using the ridge coefficient data, providing an objective base map for earth scientists to build tectonic models with quantitative evidence. Results： After the ridge coefficients are calculated, we can further enhance the boundary of high ridge-coefficient blocks, resulting in the so-called ridge-edge coefficient function. The high-value ridge-edge coefficients are well correlated with the edge faults of tectonic units underlay, providing accurate positioning of the base map for compilation of regional tectonic maps. In order to validate this new interdisciplinary analysis method, we select the Dabie orogenic zone as a pilot area for test, where rock outcrops are well exposed on the surface and detailed geological and geophysical surveys have been carried out. Tests show that the deformation bands and the tectonic units, which are conformed by tectonic scientists based on surface observations, are clearly displayed on the ridge and ridge-edge coefficient images obtained in this article. Moreover, these computer-generated images provide more accurate locations and geometric details. Conclusions： This work demonstrates that application of modern mathematical tools can promote the quantitative degree in research of modern geosciences, helping to open a door to develop a new branch of mathematical tectonics.

Bekenstein-Hawking Cosmological Entropy and Correction Term Corresponding Cosmological Horizon of Rotating and Charged Black String

Utilizing the quantum statistical method and applying the new state density equation motivated by generalized uncertainty principle in quantum gravitaty, we avoid the difficulty in solving wave equation and directly calculate the partition function of bosonic and fermionic field on the background of rotating and charged black string. Then near the cosmological horizon, entropies of bosonic and fermionic field are calculated on the background of black string. When constant A introduced in generalized uncertainty principle takes a proper value, we derive Bekenstein- Hawking entropy and the correction value corresponding cosmologicaJ horizon on the background of rotating and charged black string. Because we use the new state density equation, in our calculation there are not divergent term and small mass approximation in the original brick-wall method. From the view of quantum statistic mechanics, the correction value to Bekenstein-Hawking entropy of the black string is derived. It makes people deeply understand the correction value to the entropy of the black string cosmological horizon in non-spherical coordinate spacetime.

Case Report: Generalized Mutual Information (GMI) Analysis of Sensory Motor Rhythm in a Subject Affected by Facioscapulohumeral Muscular Dystrophy after Ken Ware Treatment

In this case report we study the dynamics of the SMR band in a subject affected from Facioscapulohumeral Muscular Dystrophy and subjected to Ken Ware Neuro Physics treatment. We use the Generalized Mutual Information (GMI) to analyze in detail the SMR band at rest during the treatment. Brain dynamics responds to a chaotic-deterministic regime with a complex behaviour?that?constantly self-rearranges and self-organizes such dynamics in function of the outside require-ments. We demonstrate that the SMR chaotic dynamics responds directly to such regime and that also decreasing in EEG during muscular activity really increases its ability of self-arrangement and self-organization in brain. The proposed novel method of the GMI is arranged by us so that it may?be used in several cases of clinical interest. In the case of muscular dystrophy here examined,?GMI?enables us to quantify with accuracy the improvement that the subject realizes during such?treatment.

GENERALIZED ENERGY CONSERVATION AND UNSTABLE PERTURBATION PROPERTY IN BAROTROPIC VORTEX

Based on a barotropic vortex model, generalized energy-conserving equation was derived and twonecessary conditions of basic flow destabilization are gained. These conditions correspond to generalizedbarotropic instability and super speed instability. They are instabilities of vortex and gravity inertial waverespectively. In order to relate to practical situation, a barotropic vortex was analyzed, the basic flow of which issimilar to lower level basic wind field of tropical cyclones and the maximum wind radius of which is 500 km.The results show that generalized barotropic instability depending upon the radial gradient of relative vorticitycan appear in this vortex. It can be concluded that unstable vortex Rossby wave may appear in barotropic vortex.

Rotating Classical Strings

It is a starting point in string theory to assume that elementary particles are in fact rotating strings, and the final goal of the theory is a complete description of fundamental physics, including general relativity. This paper is instead concerned with the reversed question: starting from general relativity, is there a good way to motivate why rotating strings should be more natural models for elementary particles than, say, spherical particles or point-particles? Also, the purpose here is not to motivate full string theory. For example, no hidden dimensions come into play, only the four usual ones, and strings are defined in a very simple geometric way. Rather, the focus is on investigating an interesting mathematical property, which implies that strings may have special features with respect to rotation which spherically symmetric particles have not. In particular, it turns out that in a certain sense rotating strings are simpler than non-rotating ones. This is a consequence of the indefinite metric, and the main result states that the curvature of a non-rotating string, as measured by the square of the scalar curvature, may be reduced by letting it rotate in an appropriate way. The calculations underlying this theorem are heavy and have partly been car-ried out using Mathematica, although in principle the essential theorem may not require super-human labour.

Radio over Fiber Architecture Very High-Speed Wireless Communications in the Unlicensed 60 GHz Band

Larger wireless access networks are required to meet the growing demand for mobile traffic and multimedia services. The use of RoF (Radio over Fiber) technology in combination with millimeter waves is a potential response to the requirements of broadband applications and high capacity networks. In this paper, we proposed a RoF architecture able to provide very high-speed wireless access points up to Gbps considering an indoor and outdoor environment conform to IEEE 802.11ad and IEEE 802.15.3c standard. Optical transmission and radio coverage have been studied by considering the uplink and downlink. System performance has been evaluated in the relation to the Error Vector Magnitude (EVM) for various modulation formats (BPSK, QPSK and 16QAM). Results showed that millimeter wave signals are successfully delivered over a 50 km fiber link and a wireless channel up to 32 m. Data throughput up to 5.28 Gbps has been reached. The proposed architecture can extend the range of applications for wireless communications in association with the unlicensed 60 GHz band with the advantages of better capacity, a wider coverage area and a reduction in the investment cost.

基于变异的正则表达式反例测试串生成算法

正则表达式在计算机科学的许多领域具有广泛应用.然而,由于正则表达式语法比较复杂,并且允许使用大量元字符,导致开发人员在定义和使用时容易出错.测试是保证正则表达式语义正确性的实用和有效手段,常用的方法是根据被测表达式生成一些字符串,并检查它们是否符合预期.现有的测试数据生成大多只关注正例串,而研究表明,实际开发中存在的错误大部分在于定义的语言比预期语言小,这类错误只能通过反例串才能发现.研究基于变异的正则表达式反例测试串生成.首先通过变异向被测表达式中注入缺陷得到一组变异体,然后在被测表达式所定义语言的补集中选取反例字符串揭示相应变异体所模拟的错误.为了能够模拟复杂缺陷类型,以及避免出现变异体特化而无法获得反例串的问题,引入二阶变异机制.同时采取冗余变异体消除、变异算子选择等优化技术对变异体进行约简,从而控制最终生成的测试集规模.实验结果表明,与已有工具相比,所提算法生成的反例测试串规模适中,并且具有较强的揭示错误能力.

数据驱动下考虑多预测误差带信息的多场景随机优化调度

针对高比例可再生能源接入电网后省级电网面临的风光功率预测不确定性大、调度决策难等问题,提出一种多场景随机优化调度模型。基于核密度估计方法引入调度预测误差带的概念,结合风光聚合场站的预测出力和实际出力构建计及时间相关性的海量随机场景,结合改进的K-means聚类与同步回代消除算法进行场景缩减,引入布莱尔分数评价削减后随机场景的性能;基于风光随机出力场景,考虑供热系统中的热用户舒适度,构建日前随机优化调度模型。基于新疆电网实际网架结构和风光实际历史出力数据进行算例验证,结果表明:所提方法生成的风光出力随机场景可以更好地描述风光的预测轨迹;相较于传统日前调度方法,基于场景法的随机优化调度模型可有效提升风光可再生能源消纳率;以供热系统中热用户舒适度为导向,热电联产机组参与热力系统热电调节可进一步降低风光弃电率。

天然氢气规模生成的成因类型与成藏特点

目前对全球天然氢气资源的估量十分巨大,寻找天然氢气的规模聚集区有赖于对其形成机理和富集规律的不断认识。通过对国内外典型天然氢气显示的数据统计,系统总结了全球天然氢气规模聚集的成因类型、并分析了天然氢气藏的分布和成藏特征。研究结果表明:①天然氢气的成因复杂多样,主要包括水岩反应、地幔脱氢、水的辐解、岩石破碎、有机质热解以及微生物作用等,其中,水岩反应生氢和地幔脱气生氢在自然界中普遍发生,在各种地质环境中广泛存在,且其生氢速率高、生氢量大,因此是天然氢气规模生成最重要的2种成因类型。②天然氢气藏的赋存环境集中体现于三大地质背景中:板块俯冲带、前寒武纪富铁地层发育区以及裂谷构造系统。③天然氢气藏的盖层条件受多个因素的影响,不仅要考虑盖层本身的封盖能力,还要考虑由于氢活跃的物理化学性质导致盖层机械性能发生的变化,影响其脆性-韧性行为形成新的裂缝而产生氢气的逃逸。④地下微生物利用氢气进行代谢活动、中深层的加氢生烃作用等耗烃作用不利于氢气规模聚集,因此在寻找天然氢气生成有利区时,应该避开氢被大量消耗的区域。⑤天然氢气的生成时间尺度短和易扩散性等因素,使得天然氢气成藏表现出动态成藏的特征,只要氢生成与散失始终处于一种动态平衡,就能够富集成藏。地下水是水岩反应生氢的必要条件,国外发现的很多天然氢气藏都分布在地下水循环较好的地区。

高中数学课堂中问题串设置艺术探研

问题串是指按照某一特定规则与方法,精心设计而成的多个问题的集合。文章在分析问题串教学法的内涵与特征、问题串的类型与设置原则的基础上,从情境导入、知识生成、例题教学、课堂小结、复习课教学、规律教学等角度,探究高中数学课堂中问题串的设置策略,并提出问题串设计应注意的问题:充分结合学生已有经验、提高问题串设计能力、准确把握问题串教学的关键环节、增强问题串设计的灵活性,以此充分发挥问题串教学法的作用,促进课堂教学效率以及学生学习效率的提升。

广义频分复用系统峰均功率比抑制算法

为了降低广义频分复用系统存在着多载波系统中固有的高峰均功率比问题,本文提出了一种适用于广义频分复用系统的子载波抑制高峰均功率比算法。该算法以限幅法为基础,降低了系统的高峰均功率比,但与限幅法不同的是,该算法几乎不会对带外性能及误码率性能造成影响。由于子载波抑制高峰均功率比算法的峰均功率比抑制性能略差于限幅法,因此本文进一步提出将部分序列传输与子载波抑制高峰均功率比结合来进一步抑制系统高峰均功率比的算法。仿真表明:本文提出的算法的高峰均功率比抑制性能与限幅法相同,且不会对系统的带外与误码率性能造成影响。

三维周期有砟轨道结构弹性波传播特性及波叠加法试验验证

为探究高速铁路有砟轨道结构中的弹性波波动行为,基于周期结构理论,采用广义平面波展开法,建立包含道砟在内的三维周期有砟轨道结构模型。然后,进行波叠加法的推导,从试验的角度反演弹性波的传播规律,验证三维轨道模型的正确性。在此基础上,计算并分析结构的能带分布以及道砟结构参数对轨道结构弹性波传播的影响。结果表明:广义平面波解析法与波叠加试验方法得到的能带分布结果基本吻合,所采用的方法正确可靠;三维有砟轨道低频阶段存在0~62,63~138,160~169和181~224 Hz共4个局域共振带隙;道砟对轨道结构频散特性的影响主要集中在低频阶段,提高道砟剪切刚度会增强结构在带隙频段内的衰减能力,剪切刚度从50 kN·mm^(-1)增至90 kN·mm^(-1),频带隙的总宽度则从180 Hz减至170 Hz,带隙宽度减小率不断提高;道砟参振质量主要影响2阶、4阶带隙的宽度,单个道砟参振质量考虑为500 kg时低频带隙宽度最大,对振动的衰减量也最大,而当它从500 kg增至800 kg时低频带隙总宽度则减小8.9 Hz。

基于改进型自抗扰的微电网负荷频率控制研究

针对可再生能源发电随机性导致微电网频率存在稳态偏差的问题,为了控制电网频率波动,在传统自抗扰控制的基础上设计了改进型自抗扰控制器,对风-光-柴-储微电网进行负荷频率的优化控制。考虑到实际存在的调速器侧隙和发电速率约束的非线性导致的系统不稳定,提出了一种针对多区域多发电机的抗饱和误差补偿策略,提高了控制器的控制性能,并将重复控制与自抗扰控制相结合,该复合控制方法提高了控制器精度,增强了系统鲁棒性。利用Simulink建立两区域电力系统负荷频率控制的仿真模型,将PID控制器、传统自抗扰控制器与改进型自抗扰控制器进行仿真比较,仿真结果表明,改进后的控制器能够迅速地将频率偏差收敛到零,从而使电网的频率保持在额定范围内,从而大大改善了系统的稳定性,提高了系统的动态性能。

基于常规岩心物性资料预测T2谱的方法

核磁共振测井对于地层流体的综合评价有着重要的作用,它也是储层开采以及解释疑难井的重要手段。为了解决井下核磁共振测井作业的参数选取问题,提高并增强井下作业的速度和效率,考虑到岩石孔隙内各流体的不同弛豫机理,开发一种预测核磁共振T_(2)谱的测前设计软件。测前设计软件由T_(2)谱构造、回波生成加噪、反演生成以及参数建议4个模块构成,能够预测地层的T_(2)谱形态,对提前认识待测量地层有重要的意义。实验结果表明,所设计软件操作简单、结果精确,可为核磁共振测井测前设计优化以及正反演等研究提供借鉴。

提高光伏发电系统效率技术实践

分析了影响光伏发电系统效率的各种因素,找出积灰遮挡是影响已投运光伏电站的关键可控因素,并提出对应的优化建议。同时优化组串设计也可实现提效降本,基于油区光伏电站实发数据及积灰影响分析结果,得到不同阶段积灰对发电效益的影响,找出清洗成本与清洗效益的平衡点,优化了清洗周期。对光伏电站组串设计时,部分变量取值进行优化,能够减少逆变器、电缆等用量,降低生产成本。通过以上措施实现光伏发电系统效率的提高。

利用互子带滤波器和稀疏特性的多通道线性预测语音去混响方法

多通道线性预测是最为流行的语音去混响方法之一,现有相关研究大多利用子带谱减模型在每一个频带独立地获取期望信号,但这忽略了不同子带之间的相互影响。本文提出一种利用互子带谱减模型的多通道线性预测语音去混响方法。相比于大多数方法采用的子带谱减模型,本文方法采用的互子带谱减模型能够利用互子带滤波器来对不同子带之间的相互影响进行建模。本文方法利用复广义高斯分布建模期望信号,相比于常用的高斯分布,复广义高斯分布能够通过调整形状参数来描述语音信号的稀疏特性。在最大似然估计框架下,将语音去混响转化为关于互子带滤波器和子带滤波器的优化问题;并且基于替代最小化方法推导了保证收敛的优化算法。在不同混响时间、不同通道、不同声源和传声器距离情况下的一系列语音去混响实验验证了本文方法的性能显著优于传统去混响算法。