The variable sampling interval run sum X‾ control chart

Traditional control charts for process monitoring are based on taking samples from the process at fixed length sampling intervals. More recently, research works focused on the use of variable sampling intervals (VSIs), where the lengths of the sampling intervals are varied according to the process quality. A short sampling interval is considered when the process quality indicates a possible out-of-control situation while a long sampling interval is considered, otherwise. In this paper, the VSI run sum (RS) $\bar{X}$ chart is proposed with its optimal scores and parameters determined using an optimization technique to minimize the out-of-control average time to signal (ATS) or the adjusted average time to signal (AATS). A Markov-chain method is used to evaluate both the ATS and AATS of the proposed chart, for the zero and steady state cases, respectively. Results show that the VSI RS $\bar{X}$ chart is considerably more efficient than the basic RS $\bar{X}$ chart. The VSI RS $\bar{X}$ chart performs generally well compared with other competing charts, such as the standard $\bar{X}$, synthetic $\bar{X}$, exponentially weighted moving average (EWMA) $\bar{X}$, VSI $\bar{X}$ and VSI EWMA $\bar{X}$ charts. The sensitivity of the VSI RS $\bar{X}$ chart can be enhanced further by adding more scoring regions or a head-start feature. An illustrative example is presented to explain the implementation of the proposed VSI RS $\bar{X}$ chart.     

A teaching–learning based optimization approach for economic design of X-bar control chart

Being simple to use X-bar control chart has been most widely used in industry for monitoring and controlling manufacturing processes. Measurements of a quality characteristic in terms of samples are taken from the production process at regular interval and the sample means are plotted on this chart. Design of a control chart involves the selection of three parameters, namely the sample size (n), the sampling interval (h) and the width of control limits (k). In case of economic design, these three control chart parameters are selected in such a manner that the total cost of controlling the process is the least. The effectiveness of this design depends on the accuracy of determination of these three parameters. In this paper, a new efficient and effective optimization technique named as teaching–learning based optimization (TLBO) has been used for the global minimization of a loss cost function expressed as a function of three variables n, h and k in an economic model of X-bar chart based on unified approach. In this work, the TLBO algorithm has been modified to simplify the tuning of teaching factor. A MATLAB computer program has been developed for this purpose. A numerical example has been solved and the results are found to be better than the earlier published results. Further, the sensitivity analysis using fractional factorial design and analysis of variance have been carried out to identify the critical process and cost parameters affecting the economic design.     

Leader-follower formation control without leader’s velocity information

In this paper,we consider the mobile robots formation control problem without direct measurement of the leader robot’s linear velocity.Two decentralized nonlinear algorithms are proposed,respectively,based on adaptive dynamic feedback and immersioninvariance estimation based second order sliding mode control methodologies.The main idea is to solve formation problem by estimating the leader robots’s linear velocity,while maintaining the given predefined separation distance and bearing angle between the leader robot and the follower robot.The stability of the closed-loop system is proven by means of the Lyapunov method.The proposed controllers are smooth,continuous and robust against unknown bounded uncertainties such as sensor inaccuracy between the outputs of sensors and the true values in collision free environments.Simulation examples and physical vehicles experiments are presented to verify the effectiveness of the proposed design approaches,and the proposed designed methodologies are carefully compared to illustrate the pros and cons of the approaches.     

Impulsive control and synchronization of Chua’s oscillators

Impulsive control of a chaotic system is ideal for designing digital control schemes where the control laws are generated by digital devices which are discrete in time. In this paper, several new theorems on the stability of impulsive control systems are presented. These theorems are then used to find the conditions under which the Chua’s oscillator can be asymptotically controlled to the origin by using impulsive control. Given the parameters of the Chua’s oscillator and the impulsive control law, an estimation of the upper bound of the impulse interval is given. We also present a theory of impulsive synchronization of two Chua’s oscillators. A numerical example and simulation illustrates the effectiveness of the proposed result. Compared with the existing results, these results are less conservative.     

Automatic control system for a pipe’s inner surface coating

Theoretical bases for controlling the application of coatings to the inner surface of pipes and other hollow products are considered based on the stabilization of the velocity of the coating material in the product cavity taking into account temperature and viscosity. The device makes it possible to automatically compensate for the variation in the coating thickness depending on temperature taking into account the characteristics of the used control equipment. The dependence of the coating thickness on temperature and material velocity is described. The system that implements the proposed method in the MATLAB + SIMULINK shell is simulated. The optimal values of the system gain and level sensor sensitivity that minimize the dynamic error of the control system are determined.     

A Reinterpretation of Beall’s ‘Off-Topic’ Semantics

Journal of Logic, Language and Information - Jc Beall’s off-topic interpretation of Weak Kleene logic offers a logic of ‘true-and-topic’ preservation. However, Nissim Francez has...     

Chang’E-2 satellite asymmetric-descent orbit control technology

To accomplish high-resolution imaging of the preselected landing area,it was necessary for the Chang’E-2 mission to perform orbital maneuvering on the far side of the moon to meet the conditional height requirement of the imaging area.Engine shut-down would be executed invisibly on the back side of the moon if the descent maneuver mode opposite to the target perilune or the fuel optimal maneuver mode was used.To ensure the satellite safety,the project collectivety required that the engine shutdown should be...     

Synthesis of stabilizing spacecraft control based on generalized Ackermann’s formula

Problem of modal synthesis of controllers and observers using the generalized Ackermann’s formula is solved for a spacecraft as a complex dynamic system with high interconnections. All possible controller matrices (the whole set of controllers) are obtained for solution of the problem of stabilization of orbital orientation of the spacecraft in inseparable channels of bank and yaw angles.     

Coating weight control on ArcelorMittal’s galvanizing line at Florange Works

ArcelorMittal’s hot dip galvanizing line at Florange has developed and commissioned its own coating weight control system. This system automatically controls air-knife pressure and position to give a constant and uniform zinc coating in accordance with customer-order specifications through a model-based feedforward controller and two feedback controllers. Moreover, continuous adaptation of the knife-to-strip distance allows a fast and accurate response to process fluctuations under the entire range of operating conditions. Due to speedy acceptance of this system by line operators, large and rapid benefits, i.e. quality improvement and zinc savings, have been achieved immediately after it was put into production.     

Goal-oriented error control in adaptive mixed FEM for Signorini’s Problem

This paper outlines goal-oriented finite element error control for Signorini’s problem. The discretization is based on a mixed formulation proposed by Hlavacek et al. which is extended to higher-order polynomials. A duality argument based on a variational inequality is applied, which allows for the estimates in h- as well as hp-adaptivity. Numerical results confirm the applicability of the theoretical findings.     

A novel approach to exploring company’s financial soundness: Investor’s perspective

Prediction of company’s life cycle stage change; creation of an ordered 2D map allowing to explore company’s financial soundness from a rating agency perspective; and prediction of trends of main valuation attributes usually used by investors are the main objectives of this article. The developed algorithms are based on a random forest (RF) and a nonlinear data mapping technique “t-distributed stochastic neighbor embedding”.Information from five different perspectives, namely balance, income, cash flow, stock price, and risk indicators was aggregated via proximity matrices of RF to enable exploration of company’s financial soundness from a rating agency perspective. The proposed use of information not only from companies’ financial statements but also from the stock price and risk indicators perspectives has proved useful in creating ordered 2D maps of rated companies. The companies were well ordered according to the credit risk rating assigned by the Moody’s rating agency.Results of experimental investigations substantiate that the developed models are capable of predicting short term trends of the main valuation attributes, providing valuable information for investors, with low error. The models reflect financial soundness of actions taken by company’s management team. It was also found that company’s life cycle stage change can be determined with the average accuracy of 72.7%. Bearing in mind fuzziness of the transition moment, the obtained prediction accuracy is rather encouraging.     

Hollnagel’s test: being ‘in control’ of highly interdependent multi-layered networked systems

Advances in technologies for networking, sensing, and automation have resulted in multi-layered networked systems that extend information gathering, interactions across roles, and the potential for control over wider ranges. But these systems also represent a scale shift in complexity in terms of the density of interdependencies across processes and activities. In the new systems, coupling has run amok introducing new challenges about how to control processes when they are part of such highly interdependent webs. Based on the joint cognitive systems perspective, Hollnagel examines, or tests, technology changes by asking two key questions: what does it mean to be in control and how can control be amplified? Hollnagel has shown that the answers to these questions are not inherent in technology itself but rather point to emergent system properties that can and should be supported to produce success and avoid failures. This paper applies Hollnagel’s test to the reverberations of technology change that are producing multi-layered networked systems. The paper shows how being ‘in control’ of multi-layered networked systems requires the ability to navigate interdependencies and shows how ‘amplifying control’ then consists of tools that help reveal/track relevant interdependencies and help anticipate how projected actions will propagate (resonate) across interdependencies relative to goals. The end result is that a shift is underway from supervisory control to polycentric control architectures.     

Using agent’s type in control problems for a multi-agent hierarchical system

The feasibility of using agent’s type in solving a constrained optimization problem for a multi-agent hierarchical system is analyzed. The existence of a threshold for agent’s type, as well as certain conditions of its incorporation into system’s goal function are established.     

Optimal control of an electric vehicle’s charging schedule under electricity markets

As increasing numbers of electric vehicles (EVs) enter into the society, the charging behavior of EVs has got lots of attention due to its economical difference within the electricity market. The charging cost for EVs generally differ from each other in choosing the charging time interval (hourly), since the hourly electricity prices are different in the market. In this paper, the problem is formulated into an optimal control one and solved by dynamic programming. Optimization aims to find the economically optimal charging solution for each vehicle. In this paper, a nonlinear battery model is characterized and presented, and a given future electricity prices is assumed and utilized. Simulation results indicate that daily charing cost is reduced by smart charing.     

A variant of Wiener’s attack on RSA

Wiener’s attack is a well-known polynomial-time attack on a RSA cryptosystem with small secret decryption exponent d, which works if d < n ^0.25, where n = pq is the modulus of the cryptosystem. Namely, in that case, d is the denominator of some convergent p _m /q _m of the continued fraction expansion of e/n, and therefore d can be computed efficiently from the public key (n, e). There are several extensions of Wiener’s attack that allow the RSA cryptosystem to be broken when d is a few bits longer than n ^0.25. They all have the run-time complexity (at least) O(D ²), where d = Dn ^0.25. Here we propose a new variant of Wiener’s attack, which uses results on Diophantine approximations of the form |α ? p/q| <  c/q ², and “meet-in-the-middle” variant for testing the candidates (of the form rq _m+1 +  sq _m ) for the secret exponent. This decreases the run-time complexity of the attack to O(D log D) (with the space complexity O(D)).     

A recursive solution for Turing’s H-M factor

Turing devised an electromechanical device, called a Bombe, to decipher German Enigma messages. His original design was considerably improved by the addition of Welchman’s diagonal board, allowing the use of much weaker menus and even menus without closures. Turing then made some extensive calculations to predict the performance of the improved Bombe. He provided a table, called the H-M factor, which allowed the expected number of stops to be predicted for menus containing a given number of letters and closures, but he gave no indication of how he constructed the table. This article is of technical interest and sheds some light on the H-M factor, including its variability with the tree-arrangement of the menu. It derives the H-M factor using a recursive technique for both the standard Bombe and the Jumbo Bombe, a later version incorporating the machine gun mechanism. These results may be of interest to those that code or run Bombe emulators.     

Web service adaptation: A decade’s overview

With the exponential growth of communication and information technologies, adaptation has gained a significant attention as it becomes a key feature of service-based systems, allowing them to operate and evolve in highly dynamic and uncertain environments. Although several Web service standards and frameworks have been proposed and extended, existing solutions do not provide a suitable architecture, in which all aspects of monitoring and adaptation (e.g., proactive, cross-layer, and autonomic adaptation) can be expressed. In addition, the emergence of new computing environments to host and execute various types of services (Web/cloud services, big data-intensive services, mobile services, microservices, etc.) raises the need for more efficient monitoring and adaptation systems. This survey aims to bring a synthesis and a road-map to the adaptation of service-based systems. We also discuss adaptation solutions in emerging service models, such as cloud services and big services. Based on an adaptation taxonomy which we extracted from the surveyed approaches, and by identifying the main requirements and goals of service adaptation in Web, cloud and big data environments, detailed analysis and discussions, as well as the open issues, are provided.     

A Parallel Method for Earth Mover’s Distance

We propose a new algorithm to approximate the Earth Mover’s distance (EMD). Our main idea is motivated by the theory of optimal transport, in which EMD can be reformulated as a familiar \(L_1\) type minimization. We use a regularization which gives us a unique solution for this \(L_1\) type problem. The new regularized minimization is very similar to problems which have been solved in the fields of compressed sensing and image processing, where several fast methods are available. In this paper, we adopt a primal-dual algorithm designed there, which uses very simple updates at each iteration and is shown to converge very rapidly. Several numerical examples are provided.     

A visualization tool of en route air traffic control tasks for describing controller’s proactive management of traffic situations

Improvements of aviation systems are now in progress to ensure the safety and efficiency of air transport in response to the rapid growth of air traffic. For providing theoretical and empirical basis for design and evaluation of aviation systems, researches focusing on cognitive aspects of air traffic controllers are definitely important. Whereas various researches from cognitive perspective have been performed in the Air Traffic Control (ATC) domain, there are few researches trying to illustrate ATCO’s control strategies and their effects on task demands in real work situations. The authors believe that findings from these researches can contribute to reveal why ATCOs are capable of handling air traffic safely and efficiently even in the high-density traffic condition. It can be core knowledge for tackling human factors issues in the ATC domain such as development of further effective education and training program of ATCO trainees. However, it is difficult to perform such kinds of researches because identification of ATC task from a given traffic situation and specification of effects of ATCO’s control strategies on task demands requires expert knowledge of ATCOs. The present research therefore aims at developing an automated identification and visualization tool of en route ATC tasks based on a cognitive system simulation of an en route controller called COMPAS (COgnitive system Model for simulating Projection-based behaviors of Air traffic controller in dynamic Situations), developed by the authors. The developed visualization tool named COMPASⁱ (COMPAS in interactive mode) equips a projection process model that can simulate realistic features of ATCO’s projection involving setting extra margins for errors of projection. The model enables COMPASⁱ to detect ATC tasks in a given traffic situation automatically and to identify Task Demand Level (TDL), that is, an ATC task index. The basic validity of COMPASⁱ has been confirmed through detailed comparison between TDLs given by a training instructor and ones by COMPASⁱ in a simulation-based experiment. Since TDL corresponds to demands of ATC tasks, temporal sequences of TDLs can reflect effectiveness of ATCO’s control strategies in terms of regulating task demands. By accumulation and analysis of such kind of data, it may be expected to reveal important aspect of ATCO’s skill for achieving the safety and efficiency of air traffic.