Explicit modeling of semantics associated with composite states in UML statecharts

UML statecharts are used for describing dynamic aspects of system behavior. The work presented here extends a general Petri net-based methodology to support formal modeling of UML statecharts. The approach focuses on the specific task of generating explicit transition models associated with the hierarchical structure of statechart. We introduce a state-transition notation to serve as an intermediate model for conversion of UML statecharts, and in particular, the complexity of composite states, to other target specifications. By defining a process for deriving, from UML statecharts, a state-transition notation that can serve as an intermediate state machine model, we seek to deepen understanding of modeling practices and help bridge the gap between model development and model analysis. This work covers all of the primary issues associated with the hierarchical structure of composite states, including entry and exit transitions, transition priorities, history states, and event dispatching. Thus, the results provide an important step forward toward the goal of modeling increasingly complex semantics of UML statecharts. This material is based upon work supported by the U.S. Army Research Office under grant number DAAD19-01-1-1-0672, and the U.S. National Science Foundation under grant number CCR-9988168.     

基于边状态枚举计算多状态网络可靠度动态界

为降低计算多状态网络可靠度的复杂性,综合考虑网络中具有多态性的边处于各中间状态的概率及从某中间状态转换到相邻状态对网络性能的影响,提出了一种基于边状态枚举计算多状态网络可靠度上下界的算法.该算法首先令网络中各边仅取完全工作和完全失效两种状态,将处于中间状态的概率分别叠加到完全工作和完全失效状态的概率上,得到可靠度上下界的初始值;而后按照对可靠度影响递减的顺序迭代枚举边的中间状态,通过集合间的比较,计算可靠度上下界的改变值,同时获得不断减小的可靠度上界和不断增加的可靠度下界,使其最终收敛于可靠度精确值.该算法不需提前求取网络d-最小割(路)集,且枚举较少的网络状态即可得到紧凑的可靠度上下界.相关引理的证明及算例分析验证了该算法的正确性和有效性.     

Fault accommodation for linear systems with time-varying delay

This paper studies the fault accommodation problem for linear systems with time-varying delay, system uncertainties and external disturbances. A novel intermediate estimator-based fault tolerant control (FTC) scheme is proposed, where an intermediate estimator is constructed to estimate the states and the faults simultaneously, based on the estimation; an FTC compensation scheme is designed to eliminate the effects of faults, system uncertainties and time-varying delay. It is proved that the states of the closed-loop system are uniformly ultimately bounded. A simulation example shows the effectiveness of the proposed method.     

Acquisition of intermediate goals for an agent executing multiple tasks

In this paper, an algorithm that acquires the intermediate goals between the initial and goal states is proposed for an agent executing multiple tasks. We demonstrate the algorithm in the problem of rearranging multiple objects. The result shows that the moving distance to transfer the entire objects to their goal configuration is 1/15 of that without using intermediate goals. We experiment using a real robot to confirm that the intermediate goal can be adapted to a real environment. Our experimental results showed that an agent could adapt the intermediate goals, which were acquired in the simulation, to the experimental environment.     

Quantum correlations in Gaussian states via Gaussian channels: steering,entanglement, and discord

Here we study the quantum steering, quantum entanglement, and quantum discord for Gaussian Einstein–Podolsky–Rosen states via Gaussian channels. And the sudden death phenomena for Gaussian steering and Gaussian entanglement are theoretically observed. We find that some Gaussian states have only one-way steering, which confirms the asymmetry of quantum steering. Also we investigate that the entangled Gaussian states without Gaussian steering and correlated Gaussian states own no Gaussian entanglement. Meanwhile, our results support the assumption that quantum entanglement is intermediate between quantum discord and quantum steering. Furthermore, we give experimental recipes for preparing quantum states with desired types of quantum correlations.     

基于缩减信念状态的Conformant 规划方法

Conformant 规划问题通常转化为信念状态空间的搜索问题来求解.提出了通过降低信念状态的不确定性来提高规划求解效率的方法.首先给出缩减信念状态的增强爬山算法,在此基础上,提出了基于缩减信念状态的Conformant 规划方法,设计了CFF-Lite 规划系统.该规划器的求解过程包括两次增强爬山过程,分别用于缩减信念状态和搜索目标.首先对初始信念状态作最大程度的缩减,提高启发函数的准确性;然后从缩减后的信念状态开始执行启发式搜索.实验结果表明,CFF-Lite 规划系统通过快速缩减信念状态降低了问题的求解难度,在大多数问题上,求解效率和规划解质量与Conformant-FF 相比,都有显著的提高.     

FDI攻击下互联电力系统的分布式安全状态估计

针对虚假数据注入(FDI)攻击下的多区域互联电力系统安全状态估计问题,提出一种分布式中间观测器,同时对各区域电力系统的状态、虚假数据注入攻击信号以及负载偏差进行估计.首先,通过将电力系统的状态和虚假数据注入攻击进行增广,得到等价的区域电力系统状态空间模型;然后,基于等价系统模型构建分布式中间观测器,对各个电力子系统分别进行安全状态估计,并设计补偿控制策略以降低虚假数据注入攻击及负载偏差带来的影响;最后,通过算例仿真验证所提出方法的可行性和有效性.     

Energy optimization for multi-level cell non-volatile memory using state remapping

Non-volatile Memory (NVM) is emerging as a promising technology to build future main memory or cache. Multi-level cell (MLC) NVM that stores multiple bits in a single cell has been developed in recent years. Different NVM technology has its own writing schemes to store multiple bits, and the amount of write energy varies across different states. For MLC Phase-Change Memory (PCM), the energy consumption of writing intermediate states, ‘01’ and ‘10’, is bigger than that of writing states ‘00’ and ‘11’. For MLC Spin-Transfer Torque Magnetic RAM (STT-MRAM), the energy consumption of flipping the left bit of a 2-bit cell is greater than that of flipping the right bit. To reduce the MLC NVM write energy consumption, we propose an encoding scheme to reduce the amount of intermediate states’ write for MLC PCM and another encoding scheme to decrease the number of the left bit flips for MLC STT-MRAM. The main idea of both schemes is state remapping. We find two minimum write frequency states and remap them to state ‘01’ and ‘10’ respectively for MLC PCM. In addition, for MLC STT-MRAM, we seeks the remapping decision that can minimize the number of the left bit flips and reduces the write of states ‘01’ and ‘10’. The experimental results show that the encoding scheme for MLC PCM saves 5.25% energy on average and the encoding scheme for MLC STT-MRAM saves 12.17% energy on average.     

The validity of the composite surface model and its applications to the modulation of radar backscatter

Abstract

The composite surface model is compared with the Kirchoff method and shown to be equivalent for radar backscatter at moderate incidence angles in most commonly occurring sea states. Based on this comparison, limits are determined for the validity of the composite surface model. The model is then utilized to study the modulation of the radar cross-section of the ocean surface by long surface waves and internal waves. It is shown that apart from the well understood tilt modulation and the direct hydrodynamic modulation of the short waves, there is also an additional indirect modulation of the radar cross-section due to the hydrodynamic modulation of the intermediate waves by the long waves. Computer simulations are used to investigae these modulation mechanisms for different sea states, incidence angles and radar frequencies. It is shown that this modulation is strongest at small incidence angles and high radar frequencies. The simulations show that internal waves may be observed by X-band and Ka-band radars due to the indirect modulation through the intermediate waves. It is also shown that, contrary to previous predictions, the indirect modulation process results in modulation of radar backscatter by surface waves that travel normal to the radar look direction.     

基于中间观测器的异构多智能体系统分布式故障估计

针对由无人机和无人车组成的异构多智能体系统,提出一种新型的基于中间观测器的分布式故障估计方法,可以实现对节点及其邻居执行器故障和系统状态的同时估计.首先,考虑到无人机在XOY平面与在OZ轴方向的运动相对独立,异构多智能体系统可以划分为由无人机和无人车组成的位置子系统的XOY平面以及无人机位置子系统的OZ轴;然后,设计基于中间变量的分布式故障估计观测器,不仅能同时估计出选定的智能体自身与其邻居的执行器故障和状态,也能克服观测器匹配条件的限制,并基于$H_\infty$性能指标求解观测器增益;最后,通过仿真实验验证所提出方法的可行性与有效性.     

On measuring nondeterminism in regular languages

It is well known that allowing nondeterminism in a finite automaton can produce in the most extreme case an exponential savings in the number of states required to recognize a regular language. This paper studies situations intermediate between forbidding nondeterminism and allowing it. The amount of nondeterminism used by a finite automaton is quantified, so that the decrease in the size of the state space that occurs as the amount of nondeterminism that is permitted increases in increments can be studied. These intermediate situations are shown always to lie between two extremes:(1) there are no savings as the amount of nondeterminism increases incrementally, so that savings occur only when the amount of nondeterminism becomes unlimited;(2) each increment of nondeterminism results in additional savings, the number s of states decreasing approximately as s^1/i, until exponential savings have been achieved after about i = logs/log log s increments.     

Direct excitation of xenon by ballistic electrons emitted from nanocrystalline‐silicon planar cathode and vacuum‐ultraviolet light emission

Abstract— To verify the possible use of energetic electrons for direct excitation of inert gas molecules, a nanocrystalline‐silicon (nc‐Si) planar ballistic emitter is operated in a high‐pressure xenon gas ambience. Under the pulse drive, vacuum‐ultraviolet (VUV) light emission is detected without any signs of discharge. The transient behavior of the VUV light emission properly corresponds to that of the nc‐Si emitter. In accordance with quantitative analyses of electron‐emission characteristics and the VUV output, the electron‐to‐photon conversion efficiency reaches 81% in the relatively efficient emitter case. The VUV output power is mainly determined from the number of electrons with energies compatible the with internal excitation of xenon. The emission spectrum observed at a pressure of 10 kPa shows peaks at 152 and 172 nm, which are thought to be originated from metastable Xe²* states. In contrast to the case of conventional impact ionization, no near‐infrared (NIR) peaks are seen in the spectrum. These results strongly suggest that the incidence of energetic electrons causes direct excitation of xenon molecules followed by radiative relaxation through intermediate states. The generated VUV light can be easily converted to visible light using a phosphor screen. As a discharge‐free VUV light emission, this phenomenon is potentially applicable to mercury‐free, high‐efficacy, and high‐stability flat‐panel light‐emitting device.     

Swarm intelligence-based extremum seeking control

This paper proposes an extremum seeking control (ESC) scheme based on particle swarm optimization (PSO). In the proposed scheme, the controller steers the system states to the optimal point based on the measurement, and the explicit form of the performance function is not needed. By measuring the performance function value online, a sequence, generated by PSO algorithm, guides the regulator that drives the state of system approaching to the set point that optimizes the performance. We also propose an algorithm that first reshuffles the sequence, and then inserts intermediate states into the sequence, in order to reduce the regulator gain and oscillation induced by population-based stochastic searching algorithms. The convergence of the scheme is guaranteed by the PSO algorithm and state regulation. Simulation examples demonstrate the effectiveness and robustness of the proposed scheme.     

Continuity of latent variable models

The authors study the continuity of the behavior of dynamical systems as a function of the parameters in their behavioral equations. A system is defined in terms of its behavior and continuity requires that this behavior be continuous in the limit. The problem is demonstrated by means of an example involving an RLC circuit whose port behavior exhibits a surprising discontinuity as a function of the numerical values of the elements in the circuit. The main result states that a system described by means of difference equations involving manifest (external) and latent (internal) variables will have a continuous behavior in the limit if the limit system is observable     

Tax evasion behavior using finite automata: Experiments in Chile and Italy

In this paper, we use a Moore Automata with Binary Stochastic Output Function in order to capture the extensive decision regarding tax evasion made by subjects in experiments run in Chile and Italy. Firstly, we show how an hypothesis about subject behavior is converted into an automaton, and how we compute the probabilities of evading for every state of an automaton. We use this procedure in order to look for the automaton which is able to anticipate the highest number of decisions made by the subjects during the experiments. Finally, we show that automata with few states perform better than automata with many states, and that the bomb-crater effect described in Mittone (2006) is a well identified pattern of behavior in a subset of subjects.     

ROUGH FINITE-STATE AUTOMATA

The concept of a rough finite-state semi-automaton, in which the result of any transition is a rough set of states, is formulated and then extended to that of a rough finite-state automaton by adding the set of accepting states. The behavior of such an automaton is defined and turns out to be a rough set of input words.     

Structure analysis of periodically controlled nonlinear systems via the stroboscopic approach

It is shown that an efficient structure analysis of periodically controlled nonlinear systems is possible by use of the computer simulation technique coupled with the stroboscopic approach. The existence and stability of every periodic state can be determined together with the dynamic behavior in the neighborhood of these periodic states. Especially, the proposed technique seems to be the only way for finding out periodic states of the saddle mode.