Current Location:home > Browse

Submitted Date

Authors

Institution

Your conditions: 201708(176)

1. chinaXiv:201708.00371 [pdf]

Synchrotron X-ray tomographic microscopy reveals histology and internal structure of Galeaspida (Agnatha)

盖志琨
Subjects: Geosciences >> Geology

Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM) is a powerful non-destructive method in paleontology, providing ultra-high-resolution 3D insights into the internal structure of fossils. Employing SRXTM, the skull specimens of Shuyu zhejiangensis, a 428 million-year-old galeaspid from the Silurian of Changxing, Zhejiang Province, are investigated. The subsequent analyses indicate that the endoskeletal skull of S. zhejiangensis is composed wholly of cartilage without convincing evidence for the presence of perichondral bone. The cranial anatomy of S. zhejiangensis are unusually preserved in three dimensions largely due to the non-random decay of the cartilaginous braincase and its connecting ‘soft’ tissues. Using Amira or Avizo software, seven virtual 3D endocasts of the skull of S. zhejiangensis were created revealing the gross internal cranial anatomy of galeaspids in great detail for the first time. The preliminary results indicate that during evolution the galeaspid head experienced a fundamental reorganization resulting in the development of jaws. 同步辐射X射线断层显微成像已经成为古生物研究中一种新的重要手段,能够在不损坏化石的前提下,提供化石内部超高分辨率的三维成像。利用瑞士光源最先进的同步辐射X射线断层显微成像技术,研究分析了七个采自浙江长兴志留系(约4.28亿年前)的早期盔甲鱼类浙江曙鱼三维立体保存脑颅化石。同步辐射X射线显微成像结果显示:盔甲鱼脑颅完全由软骨组成,并没有软骨外成骨存在的证据;盔甲鱼脑颅解剖结构能够被精细的保存下来,很大程度上归功于脑颅软骨与周围软组织在埋藏过程中的异时分解。利用AMIRA或AVIZO等计算机三维虚拟复原软件,三维虚拟复原了七个曙鱼脑颅模型,首次揭示出盔甲鱼脑颅内部详细的解剖结构。初步研究结果显示盔甲鱼的脑颅已经发生了显著的重组,具备了颌发育所必需的先决条件。

submitted time 2017-08-29 From cooperative journals:《古脊椎动物学报》 Hits3104Downloads821 Comment 0

2. chinaXiv:201708.00369 [pdf]

基于卷积神经网络的轴承故障定性诊断

单建华; 吕钦; 张神林
Subjects: Mechanical Engineering >> Other Disciplines of Mechanical Engineering

轴承定性诊断的传统方法需要复杂难懂的数学知识和高深的领域知识;基于深度置信网络的方法虽然克服了传统方法的缺点,但网络参数规模巨大,训练困难;基于时频图的卷积神经网络方法需用小波变换得到时频图。由于卷积神经网络具有强大的特征学习能力和泛化能力,提出了一种基于卷积神经网络的轴承故障定性诊断方法,直接利用一维振动信号对卷积神经网络进行训练。优势在于克服了传统方法的缺点;相比深度置信网络,网络参数少很多,训练高效;也无需小波变换得到时频图。采用西储大学和本实验室轴承数据,进行了一系列全面测试,表明本文方法能准确地定性诊断轴承故障,准确率高于其他所有方法;首次通过利用西储大学的轴承数据训练的卷积神经网络准确诊断了本实验室待测轴承的故障类型,这表明该方法能实际工程运用。

submitted time 2017-08-29 Hits7673Downloads4880 Comment 0

3. chinaXiv:201708.00367 [pdf]

内网IDS蜜罐型集成系统

孙韬
Subjects: Computer Science >> Information Security

为了应对当前日益严峻的内网安全问题,我们制作了内网蜜罐集成系统,该集成系统应用第三代蜜网部署为基础,配合IDS和防火墙来构建,使用蜜网网关转移攻击流量,建立多台蜜罐服务器,能够第一时间检测并警告管理员,使应急响应满足P2DR模型的防护时间大于检测加响应时间,分析并记录攻击手段,实现了证据留存安全迅速和内网其他主机的安全。

submitted time 2017-08-28 Hits5125Downloads2979 Comment 0

4. chinaXiv:201703.00011 [pdf]

Calorimetric Power Measurements in the EAST ECRH System

Weiye Xu
Subjects: Physics >> Nuclear Physics

In this paper, the calorimetric power measurement method for electron cyclotron resonance heating system on EAST are presented. This method requires measurement of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature is controlled to be stable to get more accurate results. The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. A novel temperature calibration method is proposed also. This kind of calibration method is accurate and effective, and can be easily implemented.

submitted time 2017-08-28 Hits3042Downloads1436 Comment 0

5. chinaXiv:201708.00366 [pdf]

时变能量网络理论

陈皓勇; 葛海麟; 邱明
Subjects: Dynamic and Electric Engineering >> Electrical Engineering

不同类型的能源系统通过能量转换设备(感应电动机、离心泵等)相互耦合,研究多类型能源系统的动态特性及其仿真方法对多能互补系统优化设计及性能分析具有重要的实际意义。为对时变能量网络进行建模和分析,本文从能量本质的角度出发,通过深入探讨能量传递及转换机理,分别建立时变传递线(管)路和能量转换设备的集中参数模型。在时变能量网络模型的基础上,提出通过构建时变能量网络方程(包括状态方程和输出方程)对多能互补系统的动态特性进行建模仿真的分析方法,最后通过具体算例对本文所提分析方法的有效性及实用性进行验证。本文的研究内容为时变能量网络的建模、分析、优化及规划奠定了基础。

submitted time 2017-08-28 Hits2831Downloads1184 Comment 0

6. chinaXiv:201708.00218 [pdf]

基于连续时间商品模型的电力市场理论

陈皓勇; 韩励佳
Subjects: Dynamic and Electric Engineering >> Electrical Engineering

实时电价理论是许多国家电力现货市场设计的理论基础,但在电力市场实践中也出现了不少问题。实时电价有两个重大缺陷:一是仍然基于传统的分时调度模型,忽略了电能生产和消费的时间连续性这个十分重要的特征,没有认真处理跨时段约束;二是假设同一时段的电能商品都是同质的,无法区别基荷、腰荷和峰荷机组区别明显的技术特征及成本构成。为克服这些缺陷,本文提出连续时间电能商品模型,包括实时电价下和按负荷持续时间定价方式下的电能商品模型,并将两种定价方式下的市场优化问题与数学上的Riemann积分和Lebesgue积分相对应,建立泛函极值优化模型,并基于Euler-Lagrange方程求得市场均衡解,通过严格的数学推导证明了按负荷持续时间定价的可行性。算例计算表明,按负荷持续时间定价能减少市场总购电费用,而且电厂利润分配较为公平。本文所提的理论和方法可为国内外电力市场建设提供全新的思路和理论基础。

submitted time 2017-08-27 Hits4652Downloads1601 Comment 0

7. chinaXiv:201708.00365 [pdf]

Mayer-Cluster Expansion of Instanton Partition Functions and Thermodynamic Bethe Ansatz

Carlo Meneghelli; Gang Yang
Subjects: Physics >> The Physics of Elementary Particles and Fields

In [18] Nekrasov and Shatashvili pointed out that the N = 2 instanton partition function in a special limit of the ?-deformation parameters is characterized by certain thermodynamic Bethe ansatz (TBA) like equations. In this work we present an explicit derivation of this fact as well as generalizations to quiver gauge theories. To do so we combine various techniques like the iterated Mayer expansion, the method of expansion by regions, and the path integral tricks for non-perturbative summation. The TBA equations derived entirely within gauge theory have been proposed to encode the spectrum of a large class of quantum integrable systems. We hope that the derivation presented in this paper elucidates further this completely new point of view on the origin, as well as on the structure, of TBA equations in integrable models.

submitted time 2017-08-25 Hits777Downloads369 Comment 0

8. chinaXiv:201708.00362 [pdf]

Cutting through form factors and cross sections of non-protected operators in N = 4 SYM

Dhritiman Nandan; Christoph Sieg; Matthias Wilhelm; Gang Yang
Subjects: Physics >> The Physics of Elementary Particles and Fields

: We study the form factors of the Konishi operator, the prime example of nonprotected operators in N = 4 SYM theory, via the on-shell unitarity method. Since the Konishi operator is not protected by supersymmetry, its form factors share many features with amplitudes in QCD, such as the occurrence of rational terms and of UV divergences that require renormalization. A subtle point is that this operator depends on the spacetime dimension. This requires a modification when calculating its form factors via the on-shell unitarity method. We derive a rigorous prescription that implements this modification to all loop orders and obtain the two-point form factor up to two-loop order and the three-point form factor to one-loop order. From these form factors, we construct an IR-finite crosssection-type quantity, namely the inclusive decay rate of the (off-shell) Konishi operator to any final (on-shell) state. Via the optical theorem, it is connected to the imaginary part of the two-point correlation function. We extract the Konishi anomalous dimension up to two-loop order from it.

submitted time 2017-08-25 Hits912Downloads470 Comment 0

9. chinaXiv:201708.00361 [pdf]

On-Shell Methods for the Two-Loop Dilatation Operator and Finite Remainders

Florian Loebbert; Dhritiman Nandan; Christoph Sieg; Matthias Wilhelm; Gang Yang
Subjects: Physics >> The Physics of Elementary Particles and Fields

We compute the two-loop minimal form factors of all operators in the SU(2) sector of planar N = 4 SYM theory via on-shell unitarity methods. From the UV divergence of this result, we obtain the two-loop dilatation operator in this sector. Furthermore, we calculate the corresponding finite remainder functions. Since the operators break the supersymmetry, the remainder functions do not have the property of uniform transcendentality. However, the leading transcendentality part turns out to be universal and is identical to the corresponding BPS expression. The remainder functions are shown to satisfy linear relations which can be explained by Ward identities of form factors following from R-symmetry

submitted time 2017-08-25 Hits831Downloads377 Comment 0

10. chinaXiv:201708.00360 [pdf]

Master integrals for the four-loop Sudakov form factor

Rutger H. Boels; Bernd A. Kniehl; , Gang Yang
Subjects: Physics >> The Physics of Elementary Particles and Fields

The light-like cusp anomalous dimension is a universal function in the analysis of infrared divergences. In maximally (N = 4) supersymmetric Yang– Mills theory (SYM) in the planar limit, it is known, in principle, to all loop orders. The non-planar corrections are not known in any theory, with the first appearing at the four-loop order. The simplest quantity which contains this correction is the four-loop two-point form factor of the stress tensor multiplet. This form factor was largely obtained in integrand form in a previous work for N = 4 SYM, up to a free parameter. In this work, a reduction of the appearing integrals obtained by solving integration-by-parts (IBP) identities using a modified version of Reduze is reported. The form factor is shown to be independent of the remaining parameter at integrand level due to an intricate pattern of cancellations after IBP reduction. Moreover, two of the integral topologies vanish after reduction. The appearing master integrals are cross-checked using independent algebraic-geometry techniques explored in the Mint package. The latter results provide the basis of master integrals applicable to generic form factors, including those in Quantum Chromodynamics. Discrepancies between explicitly solving the IBP relations and the MINT approach are highlighted. Remaining bottlenecks to completing the computation of the four-loop non-planar cusp anomalous dimension in N = 4 SYM and beyond are identified.

submitted time 2017-08-25 Hits792Downloads357 Comment 0

12345678910  Last  Go  [18 Pages/ 176 Totals]