A Comparative Analysis of Machine Learning Techniques for Muon Count in UHECR Extensive Air-Showers

The main goal of this work is to adapt a Physics problem to the Machine Learning (ML) domain and to compare several techniques to solve it. The problem consists of how to perform muon count from the signal registered by particle detectors which record a mix of electromagnetic and muonic signals. Finding a good solution could be a building block on future experiments. After proposing an approach to solve the problem, the experiments show a performance comparison of some popular ML models using two different hadronic models for the test data. The results show that the problem is suitable to be solved using ML as well as how critical the feature selection stage is regarding precision and model complexity.     

On the control of quantum statistical systems

The problem of preparing a system in some initial configuration is discussed for quantum statistical systems whose dynamics are generated by Markovian semigroups. The system is regulated by a set of controls and the central problem is to determine how the controls should be varied in order to bring the system as close as possible to the desired configuration in a fixed finite time. General equations are derived which allow one to determine how the controls should be regulated. The application of the result to a simple system is outlined.     

通过习题分析让学生充分认识建模的重要性

力学课一个重要的任务是培养学生对建模的认识．刚进入大学的学生都很习惯解题,但他们并不清楚题目是如何来的．通过对一些习题的分析,可以让学生们理解一个实际问题是如何变成题目的,让他们认识到建立正确的模型对问题的解决至关重要．     

A functional approach to the many-body nuclear problem: the MEC

Summary We show how a functional approach to the nuclear many-body problem can provide a unified scheme to deal with the many facets of the problem and to establish well-defined procedures of approximation. We consider, in particular, the perturbative and the mean-field (loop expansion) approximations to an exact effective bosonic Lagrangian, discussing how well-known computational schemes (hole-line expansion, RPA, etc.) may be obtained as subsets of definite orders in these expansions. An application to the calculation of the longitudinal electromagnetic response function, with the simpleNπ interaction, is finally presented. We show how the pion dynamic and the short-range correlations cooperate to obtain a better agreement with experimental data. Presented by R. Cenni.     

单轮电机失效时四轮轮毂电动汽车各驱动模式转向特性研究

本文在对轮胎侧偏特性和轮胎力研究的基础上,提出了四轮轮毂电动汽车四种驱动模式的转向力矩分配问题。通过数学分析,将此问题转化为一个有约束条件的最优化求解问题,接着使用MATLAB优化工具箱,并采用有效集算法对此优化问题进行求解,最终解决了单轮电机失效时四种驱动模式的选择问题,为改善单轮电机失效时四轮轮毂电动汽车的转向特性,防止车辆侧滑失稳提供了理论依据。最后采用汽车动力学仿真软件TESIS DYNAware对所提理论的正确性进行了仿真验证。     

Sense and nonsense in the renormalization-scheme-dependence problem

I discuss in detail the issues involved in the renormalization-scheme-dependence problem in perturbative QCD. The problem is not to find a good universal scheme; nor is it a question of how to make coefficients small. The problem is that finite-order results depend on the choice of scheme, even though it is “arbitrary” (in that the exact result is scheme independent). Only the “principle of minimal sensitivity” approach gets to the heart of the problem, and attempts to reconcile this contradiction. I explain the motivation for this approach, defend it against recent criticisms, and explain to what extent it provides a solution to the problem.     

加强普通物理实验课的系统性，提高教学水平

普通物理实验大多数都有各自的独立性，如何使之系统化是一个很重要的问题。     

Resolving the measurement problem: reply to Allen Stairs

We defend an account of quantum measurement as a species of selective interactions, an account that gets beyond the insolubility theorem to resolve the quantum measurement problem. In the course of the defense we propose a novel analysis of inexact measurements and discuss the problem of how to treat the states and selective interactions of composite systems.     

Monodromy Deformation Approach to Nonlinear Equations — A Survey

Monodromy deformation approach to nonlinear partial differential equation is discussed in a pedestrian's way. The whole methodology is discussed on the basis of Massive Thirring Model. In the first section of our paper we discuss the basic terminologies amociated with the deformation problem. In the next part the problem is defined on the basis of the Lax pairs for the Thirring model, and it is explicitly demonstrated that how one can determine the asymptotic expansions near a regular and irregular singularity, and hence the Stokes multipliers. Thirdly we show how to determine the “third” equation in according to Its. In the determination of the asymptotic expansion we have discussed the role played by both the WKB approximation and the series solution. In the fourth section we briefly consider the problem when the nonlinear field variables are taken to be fermionic.     

Envelope-soliton propagation for three interacting coherent excitations in a dispersive medium

An initial value problem is set up to describe propagation of a low-frequency wave-field interacting with two almost transparent wave-fields in a dispersive medium. With no linear loss, perfect phase-matching, and equal group velocities for the two high-frequency wave-packets, it is shown how the solution of the above problem can evolve to well-known soliton solutions of the sine-Gordon equation. Other attempts for solving the more general problem in which all the group velocities are different are also discussed.     

A Physical Approach to Tsirelson’s Problem

Tsirelson’s problem deals with how to model separate measurements in quantum mechanics. In addition to its theoretical importance, the resolution of Tsirelson’s problem could have great consequences for device independent quantum key distribution and certified randomness. Unfortunately, understanding present literature on the subject requires a heavy mathematical background. In this paper, we introduce quansality, a new theoretical concept that allows to reinterpret Tsirelson’s problem from a foundational point of view. Using quansality as a guide, we recover all known results on Tsirelson’s problem in a clear and intuitive way.     

Geodesically equivalent metrics in general relativity

We discuss whether it is possible to reconstruct a metric from its nonparameterized geodesics, and how to do it effectively. We explain why this problem is interesting for general relativity. We show how to understand whether all curves from a sufficiently big family are nonparameterized geodesics of a certain affine connection, and how to reconstruct algorithmically a generic 4-dimensional metric from its nonparameterized geodesics. The algorithm works most effectively if the metric is Ricci-flat. We also prove that almost every metric does not allow nontrivial geodesic equivalence, and construct all pairs of 4-dimensional geodesically equivalent metrics of Lorentz signature.     

量子力学中的时间

研究量子力学中的时间问题，既存在理论价值也有实用价值.由于时间在传统量子力学理论中扮演一个参数而不是力学量算符的角色，这使得人们在研究某个物理过程的时间问题时，总要面临如何构造时间算符和计算平均时间的问题.在本文中，我们将系统地给出构造时间算符和求时间的量子力学平均的一般方法. 关键词： 时间算符 平均时间 自共轭性 能量平移     

Ion–laser interactions: The most complete solution

Trapped ions are considered one of the best candidates to perform quantum information processing. By interacting them with laser beams they are, somehow, easy to manipulate, which makes them an excellent choice for the production of nonclassical states of their vibrational motion, the reconstruction of quasiprobability distribution functions, the production of quantum gates, etc. However, most of these effects have been produced in the so-called low intensity regime, this is, when the Rabi frequency (laser intensity) is much smaller than the trap frequency. Because of the possibility to produce faster quantum gates in other regimes it is of importance to study this system in a more complete manner, which is the motivation for this contribution. We start by studying the way ions are trapped in Paul traps and review the basic mechanisms of trapping. Then we show how the problem may be completely solved for trapping states; i.e., we find (exact) eigenstates of the full Hamiltonian. We show how, in the low intensity regime, Jaynes–Cummings and anti-Jaynes–Cummings interactions may be obtained, without using the rotating wave approximation and analyze the medium and high intensity regimes where dispersive Hamiltonians are produced. The traditional approach (low intensity regime) is also studied and used for the generation of non-classical states of the vibrational wavefunction. In particular, we show how to add and subtract vibrational quanta to an initial state, how to produce specific superpositions of number states and how to generate NOON states for the two-dimensional vibration of the ion. It is also shown how squeezing may be measured. The time dependent problem is studied by using Lewis–Ermakov methods. We give a solution to the problem when the time dependence of the trap is considered and also analyze a specific (artificial) time dependence that produces squeezing of the initial vibrational wave function. A way to mimic the ion–laser interaction via classical optics is also introduced.     

基于遗传算法的变电站巡检机器人任务路径规划方法研究

近年来,随着变电站巡检机器人在变电站中的广泛使用,巡检机器人路径规划问题越来越成为亟待解决的问题。巡检机器人在已知的拓扑地图中标记了待执行巡检任务的停靠点,不同任务需要从初始点出发经过不同的一系列停靠点再返回初始点,如何规划路径是机器人面临的问题。首先分析了路径规划面临的问题,然后通过分析拓扑地图的特征,对地图进行等价简化,再对问题进行建模使用遗传算法求解巡检任务路径规划的近似最优解。通过仿真实验证明,提出的基于遗传算法的路径规划方法是可行有效的,为变电站巡检机器人任务路径规划提供了一种有效方法。     

On a biseparability criterion of bipartite qudit state

In this paper, we propose a new approach to tackle the separability problem for bipartite qudit mixed-states. This is based on the Majorana representation which allows to represent a N-spinors(qudit) as a symmetric state of N spin-1/2. We also discuss how we can exploit such representation and the notion of the biseparability of multipartite qubit states in the sense to establish new criteria of the separability problem based on the PPT and concurrence.     

On the inverse problem in statistical mechanics

For quantum spin systems it is known that for a suitable space of potentials the equilibrium states areW*-dense in the set of all translation invariant states. The problem discussed in this paper is how to recognize such equilibrium states and how to find the corresponding potential. A necessary and sufficient condition for a state to be an equilibrium state for some potential is given in Sect. 3.