A Coaccelerated Observer

We analyze the situation of an observer coaccelerated relative to a linearly accelerated charge, in order to find whether he can observe the radiation emitted from the accelerated charge. It is found that the seemingly special situation of the coaccelerated observer relative to any other observer, is deduced from a wrong use of the retarded coordinate system, when such a system is inadmissible. It is also found that the coaccelerated observer has no special position other than any other observer, and hence, he can observe any physical events as any other observer.     

The Observer Determination

Quantum measurement requires an observer to prepare a specific measuring device among alternatives where the prepared basis of states, representing the device, is the way the observer interprets quantum reality into his macroscopic word. We redefine that observer role through a new concept: The observer determination, that is, a selection between the measurement options facing the observer. Unlike the measurement itself that is rationalized as dictated by nature, the observer determination can neither be measured nor proven to be true or false. In this paper we propose a mathematical formalism demonstrating how to define the observer determination. Moreover, we present a scheme showing how the apparently subjective observer determination transform into a measurable quantity.     

Topology identification for a class of complex dynamical networks using output variables

A problem of topology identification for complex dynamical networks is investigated in this paper. An adaptive observer is proposed to identify the topology of a complex dynamical networks based on the Lyapunov stability theory. Here the output of the network and the states of the observer are used to construct the updating law of the topology such that the communication resources from the network to its observer are saved. Some convergent criteria of the adaptive observer are derived in the form of linear inequality matrices. Several numerical examples are shown to demonstrate the effectiveness of the proposed observer.     

Length measurement in accelerated systems

We investigate the limitations of length measurements by accelerated observers in Minkowski spacetime brought about via the hypothesis of locality, namely, the assumption that an accelerated observer at each instant is equivalent to an otherwise identical momentarily comoving inertial observer. We find that consistency can be achieved only in a rather limited neighborhood around the observer with linear dimensions that are negligibly small compared to the characteristic acceleration length of the observer.     

Irreversibility and quantum measurement—The observer’s role

The role of the observer in physical theories in the sense of the observer’s viewpoint determining prominent features of the observed phenomena is discussed with reference to the problem of irreversibility and quantum measurement, the latter being closely related to the problem of classical behaviour of quantum systems. A completely subjective interpretation of irreversibility is proposed. It is claimed that irreversibility belongs only to phenomena as observed by a restricted observer who must project all phenomena on a restricted subset of the set of all possible states. The possibility of a completely unrestricted observer who does not see irreversibility is discussed.     

Falling into a Schwarzschild black hole

Consider a radially freely falling observer who plunges into a Schwarzschild black hole. In contrast to a static observer, he will have a different view of the black hole and of the outer sky. Furthermore, the relationship between the proper time of the falling observer and the proper time of a distant static observer differs from the relationship between the proper times of two static observers or two freely falling observers.     

Radiation from a uniformly accelerated charge

The electromagnetic field associated with a uniformly accelerated charge is studied in some detail. The equivalence principle paradox that the co-accelerating observer measures no radiation while a freely falling observer measures the standard radiation of an accelerated charge is resolved by noting that all the radiation goes into the region of space time in-accessible to the co-accelerating observer.     

Fault diagnosis of time-delay complex dynamical networks using output signals

This paper proposes a novel approach for fault diagnosis of a time-delay complex dynamical network.Unlike the other methods,assuming that the dynamics of the network can be described by a linear stochastic model,or using the state variables of nodes in the network to design an adaptive observer,it only uses the output variable of the nodes to design an observer and an adaptive law of topology matrix in the observer of a complex network,leading to simple design of the observer and easy realisation of topology monitoring for the complex networks in real engineering.The proposed scheme can monitor any changes of the topology structure of a time-delay complex network.The effectiveness of this method is successfully demonstrated by virtue of a complex networks with Lorenz model.     

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根据狭义相对性原理,应用Lorentz变换法则,从相对运动媒质静止参考系中的有关结论,获取了实验室参考系中所需结果。通过证明平面波相位是Lorentz不变量,指出实验室参考系中平面波解的存在性。由Lorentz变换导出了实验室参考系中平面波色散关系表示式,据此给出运动媒质的波动方程。由Lorentz变换导出运动媒质中平面波Maxwell方程。基于这些结果,应用Lorentz变换获得了平面波从自由空间垂直入射到各向同性运动等离子体半空间时反射波与透射波的有关特性。     

Application of partial observability for analysis and design of synchronized systems

Synchronization in identical drive-response systems is a problem that can be cast in an observer design framework. In this paper we extend this approach by studying the analysis/design of partial synchronization by means of observer theory. In doing so, we introduce the concept of partial observer--an observer to reconstruct a part of the system state vector. It is also shown how the observability condition can be utilized to analyze the dynamics in an array of coupled identical systems.     

转盘观者一定观测到科氏力吗

指出了转盘上的观者在观测一个相对于他运动的质点时，该质点是否受到科氏力只取决于该观者是否有自转而与转盘的转动（即观者的“公转”）无关．     

Orthonormal tetrad transport. II. Physical identification of the normals and curvatures of a time-like curve

A flat space-time time-like curve is considered from the point of view of an instantaneous comoving inertial observer. In the context of the ‘vierbein’ formalism a projection operator is introduced, able to project 3-vectors, belonging to the 3-space of the comoving observer, out of space-time 4-vectors. The motion of an accelerated particle relative to the comoving inertial frame is briefly reviewed by means of the projection technique, and the three space-like components of the Frenet-Serret tetrad are thus projected, and their motion relative to the comoving observer neatly stated. Finally, the physical identification of the normals and the curvatures obtains in terms of three-dimensional kinematics as seen by the instantaneous comoving observer.     

Wave-packet reduction as a medium of communication

Using an apparatus in which two scalers register decays from a radioactive source, an observer located near one of the scalers attempted to convey a message to an observer located near the other one by choosing to look or to refrain from looking at his scaler. The results indicate that no message was conveyed. Doubt is thereby thrown upon the hypothesis that the reduction of the wave packet is due to the interaction of the physical apparatus with the psyche of an observer. A. Einstein⁽¹⁾     

Synchronization of chaotic systems based on adaptive observer design

The synchronizing problem of a chaotic system is investigated based on the observer design. The nonlinear section is assumed to satisfy the Lipschitz condition. Firstly, the normal observer is designed based on the known Lipschitz constant and the results are given in linear matrix inequality (LMI) form. Then a fairly simple adaptive observer is designed with the Lipschitz constant unknown. Simulations on synchronizing the Lorenz system are investigated and the results show the validity and feasibility of our main results.     

Quantum mechanics and the local observer

A notion of local observer inspired by the work of Segal is introduced here in the Hilbert space theory of quantum mechanics. The local observer finds a mathematical place in the Hilbert space through local negation or complementation. A logicomathematical theory of local negation is presented and its implications for quantum logic and the problem of measurement are discussed. The setting is constructivist mathematics and the main result of the paper states that the introduction of a local observer implies the nonorthocomplementability of the whole Hilbert space even in the finite-dimensional case. Making a mathematical place for the observer (the “projector”) thus modifies the structure of the observables or the system of the projections, in accordance with a nonclassical theory of quantum-mechanical measurement.     

Nonlinear observer for synchronization of chaotic systems with application to secure data transmission

The main issue of this work is related with the design of a class of nonlinear observer in order to synchronize chaotic dynamical systems in a master-slave scheme, considering different initial conditions. The oscillator of Chen is proposed as a benchmark model and a bounded-type observer is proposed to reach synchronicity between both two chaotic systems. The proposed observer contains a proportional and sigmoid form of a bounded function of the synchronization error in order to provide asymptotic synchronization with a satisfactory performance. Some numerical simulations were carrying out in order to show the operation of the proposed methodology, with possible applications to secure data communications issues.     

基于高增益降维观测器的一类混沌同步

针对一类混沌系统, 当不满足观测器匹配条件时, 讨论了基于观测器的混沌同步及保密通讯问题.通过设计辅助驱动信号, 使得观测器匹配条件得以满足.为了处理辅助驱动信号中的未知变量, 使用高增益观测器作为近似微分器, 不仅给出了辅助驱动信号的估计值, 还给出了辅助驱动信号的微分估计值.基于辅助驱动信号的估计值, 提出了一种能与非线性项和干扰影响解耦的降维观测器作为响应系统, 达到了与驱动系统的同步.在同步的基础上, 再基于辅助驱动信号及其微分的估计值, 提出了一种保密信息还原的方法.最后, 针对Rössler系统进行仿真, 仿真结果表明所提出的方法是有效的. 关键词： 辅助驱动信号 混沌同步 降维观测器 保密通讯