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1. chinaXiv:202103.00069 [pdf]

常规电子直线加速器的设计

朱雄伟
Subjects: Physics >> Nuclear Physics

本文讨论了常规电子直线加速器的设计问题, 并以一台 10 MeV 的电子直线加速器为例穿插其中讨论了常规电子直线加速器的设计。常规电子直线加速器由电子枪、聚束部分、光速部分所组成,而且在直线对撞机装置、自由电子激光装置中经常用到束团压缩部分。我们对每一部分都进行了分析与讨论,主要包括纵向、横向束流动力学方面, 总结了一系列的行之有效的设计思想与方法。

submitted time 2021-03-03 Hits117Downloads80 Comment 0

2. chinaXiv:202103.00045 [pdf]

巴丹吉林沙漠植被群落特征与土壤水分关系研究

秦洁; 司建华; 贾冰; 赵春彦; 李端; 罗欢; 任立新
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

通过对巴丹吉林沙漠周边及腹地进行野外调查采样,归纳出该区植被的生活型和群落类型,分析其植被多样性、优势度及均匀度指数,进而探讨该地区植被群落特征对土壤水分的响应。结果表明:(1)本次调查共记录到20科52属56种植物,分属于乔木、小乔木、灌木、小灌木、半灌木、草质藤本、多年生草本、一年生草本8类生活型,群落多以灌木和多年生草本植物为主,且多为沙漠旱生或超旱生多年生植物;(2)巴丹吉林沙漠群落整体生物多样性指数偏低,沙漠腹地湖泊周围物种丰富度和多样性指数相对较高,边缘地区较低,且灌木层在群落中占优势且分布均匀,草本层植被种类多样;(3)巴丹吉林沙漠土壤含水量普遍较低,超过61%的区域土壤含水量不足5%;土壤含水量与Simpson优势度指数(C)为极显著负相关,与Shannon-Winner多样性指数(H′)、Simpson多样性指数(D)、Alatato均匀度指数(Ea)均为极显著正相关,且Simpson优势度指数(C)、Shannon-Winner多样性指数(H′)、Simp?son多样性指数(D)对土壤水分的响应关系中均为立方函数拟合效果最好。

submitted time 2021-03-02 From cooperative journals:《干旱区研究》 Hits35Downloads22 Comment 0

3. chinaXiv:202103.00011 [pdf]

理想气体与真空的类比研究

庞成群
Subjects: Physics >> The Physics of Elementary Particles and Fields

本文对理想气体与真空的类比研究。在这种类比下,质量来源于流体的漂移质量,而一定的假设下,质能方程及质速关系也能得到,并进一步可导出洛伦兹变换。

submitted time 2021-02-26 Hits40Downloads19 Comment 0

4. chinaXiv:201904.00075 [pdf]

A new approach to characterize the violation of Lorentz invariance

胡锦文
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics

本文引入了一个参量n来表征不同惯性系间光速的变化。为了满足众所周知的基本原理,又不违背一些可靠的实验结果,我们应该对n施加一些必要的约束。首先,重要的是,n的引入应该符合以下三个原则:(1)我们可以用一个规定的时钟同步来定义整个空间中的时间;(2)时间是均匀的,空间是各向同性的;(3)所有的惯性系统都是等价的,这是对狭义相对论(SR)思想的继承。在n的一些约束条件下,我们构造了一个满足惯性系对称性的一般坐标变换。近年来,许多理论都表现出对超高能量尺度下洛伦兹不变性的破坏的兴趣,例如量子引力,它暗示粒子的能量有一个有限值(称为普朗克能量),而不是从洛伦兹模型导出的无限值。因此我们构造一个n的表达式来描述洛伦兹模型的违逆。进一步,通过与著名的彩虹模型比较,我们发现本文推导的“最大能量”与彩虹模型假设的“最大能量”有一定的关系。

submitted time 2021-02-25 Hits13103Downloads531 Comment 0

5. chinaXiv:202102.00080 [pdf]

Development of X-ray spectrometer automatic adjustment system based on global optimization algorithm

Fei Zhan
Subjects: Physics >> Nuclear Physics

In high energy resolution X-ray spectroscopy beamlines of synchrotron radiation (SR) facilities and laboratory XAS/XES spectrometer, it is important to keep X-ray spectrometer operating in optimal conditions. The adjusting process is normally very time consuming due to the irregular light source beam point, and it is difficult to get global optimum. This study aims to develop an intelligent adjusting system based on global optimization algorithm for spectrometers on SR beamlines and on laboratory x-ray source. First of all, based on the two dimensional experimental data, automatic adjustment process was established. Then the automatic optimization was applied to adjust X-ray spectrometer practically, and upgraded iteratively. The online testing is carried out on a self-developed laboratory XAS spectrometer. Online tests results show that this automatic adjustment process converges to the optimal solution quickly, and the convergence time is about several dozens to hundreds steps, more efficient than manual optimization process. After automatic adjustment, we can get correct X-ray absorption spectrum based on the adjusted spectrometer.

submitted time 2021-02-25 Hits138Downloads64 Comment 0

6. chinaXiv:202102.00029 [pdf]

从划分到螺旋:符号观点看动力系统熵与混沌.pdf

邹丹旦
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

本文从符号与信息的角度,对混沌动力系统的特性进行了分析。提出了基于集合划分的信息熵传递特性,对连续动力系统引入有限测量精度假设,由此得出形成混沌的两个必要机制:信息由小尺度向宏观大尺度的转移及宏观信息的不断耗散,并进而对物理系统中的信息耗散进行分析讨论。

submitted time 2021-02-14 Hits321Downloads135 Comment 0

7. chinaXiv:202102.00063 [pdf]

Quantum entanglement measurement based on belief entropy

Xue, Yige; Deng, Yong
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Partial entropy entanglement is a very popular method to measure the entanglement of quantum systems, which is based on the classic von Neumann entropy. However, because of the problem of classical von Neumann entropy in measuring the uncertainty of quantum systems, the partial entropy entanglement is not efficient enough to measure the entanglement of quantum systems. The new entropy measure of quantum uncertainty is a model for measuring the uncertainty of a quantum system based on the classic von Neumann entropy and belief entropy, which has higher performance than the classic von Neumann entropy in measuring the uncertainty entropy of a quantum system.Based on the new entropy measure of quantum uncertainty and the classic partial entropy entanglement, this paper proposes a new model to measure the quantum entanglement measurement, named quantum entanglement measurement based on belief entropy. When the new entropy measure of quantum uncertainty degenerates to classical von Neumann entropy, the quantum entanglement measurement based on belief entropy will degenerate to classical partial entropy entanglement. Numerical examples are used to prove that quantum entanglement measurement based on belief entropy is more efficient and reliable in measuring the entanglement of quantum systems than the classic partial entropy entanglement. The experimental results show that the quantum entanglement measurement based on belief entropy can measure the uncertainty of quantum systems more efficiently and reliably than the classical classic partial entropy entanglement.

submitted time 2021-02-10 Hits125Downloads60 Comment 0

8. chinaXiv:202102.00030 [pdf]

A new entropy measure of quantum system uncertainty

Yige Xue; Yong Deng
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Quantum theory is currently the most important research field. Before processing the information of a quantum system, we must first understand how to measure the uncertainty of a quantum system. Von Neumann entropy is a very classic method to measure the uncertainty of quantum systems. However, due to the particularity of quantum systems, it is very difficult to measure the uncertainty of quantum systems, so that the measurement efficiency of the classical von Neumann entropy is not high in some cases. Based on the classic von Neumann entropy and belief entropy, this paper proposes a new entropy model to measure the uncertainty of quantum systems, which can use fully the eigenvalues and eigenvectors of the density matrix of quantum systems, and give the uncertainty of the quantum system. Some numerical examples are used to prove that the proposed entropy is more efficient and reliable in measuring quantum systems than the classical von Neumann entropy. The experimental results show that the proposed entropy can measure the uncertainty of quantum systems more efficiently and reliably than the classical von Neumann entropy.

submitted time 2021-02-04 Hits334Downloads210 Comment 0

9. chinaXiv:202102.00016 [pdf]

三维晶体中的演生粒子百科

余智明; 张泽英; 刘贵斌; 吴维康; 李小平; 张闰午; 杨声远; 姚裕贵
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems. Novel particles, emerged as excitations around exotic band degeneracy points, continue to be reported in real materials and artificially engineered systems, but so far, we do not have a complete picture on all possible types of particles that can be achieved. Here, via systematic symmetry analysis and modeling, we accomplish a complete list of all possible particles in time reversal-invariant systems. This includes both spinful particles such as electron quasiparticles in solids, and spinless particles such as phonons or even excitations in electric-circuit and mechanical networks. We establish detailed correspondence between the particle, the symmetry condition, the effective model, and the topological character. This obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.

submitted time 2021-02-02 Hits375Downloads171 Comment 0

10. chinaXiv:201904.00075 [pdf]

A new Lorentz violating model with particle’s "maximum energy"

胡锦文
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics

在Lorentz破缺模型中,通常会讨论彩虹模型,因为彩虹模型可以使粒子的能量具有极限而不是与Lorentz变换相对应的具有无限值,而这在量子引力中被认为是必需的。然而,本文表明,当我们只是坚持时空是均匀的,空间是各向同性的并且所有惯性系统都是等价时,并没有必要将光速限制为常数。并且由于光速的变化,我们可以完全构造惯性系统的坐标变换,使粒子的能量有一个极限,而这与彩虹模型相同。 此外,在最近的论文中,作为超高能量尺度的测试,彩虹模型用于研究伽马射线爆,例如GRB 160509A事件,该事件强烈暗示光速随其能量变化的线性形式。所以我们也分析了这个事件,发现我们的模型和彩虹模型之间存在联系。最后,我们简要讨论了如何在超高能量级的未来粒子实验中验证这两个模型。

submitted time 2021-01-24 Hits13151Downloads578 Comment 0

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