Formal design and analysis of FMS controller

In this paper, we study the scheduling problem with resource constraints using the Petri nets based on the transitive matrix P-invariant. This work focuses on the analysis of a cyclic schedule for the determination of the optimal cycle time and minimization of work-in-process. Especially, this paper deals with product FMS cyclic scheduling problem with each other products using the transitive matrix. The time Petri net slice is applied to analyze this FMS model. We can divide the original system into subsystems using the transitive matrix and permutate these sub-nets for analyzing the optimal scheduling.

We advocate goal-oriented software security engineering to produce highly secure software in a constructive,provable and cost-effective manner. Our approach is to couple goal-oriented semi-formal requirements specifications with formal design and implementation. To this effect, we proposed FADES (formal analysis and design for engineering security)in as the first goal-oriented software security engineering approach that provides a systematic and automated bridge between the goal-directed semi-formal KAOS (knowledge acquisition for automated specifications) framework and the B formal method to derive formal design and implementation from security requirements. In this paper, we demonstrate the applicability of FADES and study its effectiveness through a generic Electronic Smart Card case study and a comparative analysis between FADES and strictly applying formal methods.We use the case study to demonstrate how the goal-oriented formulation of security requirements in FADES paves the way for formal design that provably preserves the security properties.Further, the results of the comparison between FADES and Z show that FADES achieves better requirements completeness,consistency and security quality.

Optimal adaptive scheduling and control of beer membrane filtration

A Lift Dispatching System (LDS) is a typical real-time system that is highly complicated in design and implementation. This article presents the formal design, specification, and modeling of the LDS system using a denotational mathematics known as Real-Time Process Algebra (RTPA). The conceptual model of the LDS system is introduced as the initial requirements for the system. The architectural model of the LDS system is created using RTPA architectural modeling methodologies and refined by a set of Unified Data Models (UDMs). The static behaviors of the LDS system are specified and refined by a set of Unified Process Models (UPMs) for the lift dispatching and serving processes. The dynamic behaviors of the LDS system are specified and refined by process priority allocation and process deployment models. Based on the formal design models of the LDS system, code can be automatically generated using the RTPA Code Generator (RTPA-CG), or be seamlessly transferred into programs by programmers. The formal models of LDS may not only serve as a formal design paradigm of real-time software systems, but also a test bench of the expressive power and modeling capability of exiting formal methods in software engineering.

The purpose of this chapter is to study analytically the optimal behavior of different flexible manufacturing systems in different production environments. The instruments of the study are the maximum principle and variational analysis conducted for scheduling problems which are constructed from the modeling elements described in Chapter 5. Due to such a constructive approach, a great many models of different FMS can be investigated. As in the chapters of part II, analysis of the maximum principle leads to properties which the optimal solution must satisfy. Such properties provide a better understanding of the optimal behavior of a production system and facilitate construction of numerical methods for approximating the optimal solutions.

The sum-rate capacity of downlink channel can be significantly improved via optimal multi-user scheduling. However, in the time-varying channel, the optimal scheduling is difficult to be implemented when the dedicated feedback link existing delay. In this paper, the performance of multi-user scheduling over time-varying channel is investigated, and an analytical expression of sum-rate capacity is derived. In order to overcome the negative effect of feedback delay on system performance, an improved user scheduling is proposed based on the predicted best channel quality. Numerical simulation results demonstrate the proposed user scheduling can effectively improve the system performance, even the predictor order is 2.

In this paper, we study scheduling schemes for a two-user two-way relaying system. Two transmission modes are considered, i.e., point-to-point direct transmission and two-way amplify-and-forward (AF) relaying. An optimal scheduling method that opportunistically selects the best transmission mode for each user with instantaneous channel state information (CSI) is proposed to minimize the sum bit-error-rate (BER). However, for optimal scheduling, the scheduler requires the knowledge of all the channels. To reduce the feedback information of CSI, we also propose a suboptimal scheduling scheme that only the CSI of the two direct links is explored to select the transmission mode. Simulation results show that both the optimal and suboptimal schemes outperform the fixed direct transmission and fixed two-way relayed transmission, and the performance gap between the optimal and suboptimal scheduling scheme is small. These results show that the suboptimal scheduling scheme provides a good trade-off between implementation complexity and system performance.

This paper explores optimal and suboptimal packet schedulers for time-varying flat fading channels that trade-off between minimization of the average delay and the average transmitted power. Both uncorrelated and correlated block fading channels are investigated. Extending a previous work, we formulate the trade-off as a unconstrained Markov decision processes and find the stationary deterministic optimal policy using both relative value iteration and policy iteration algorithm. As well, we present constrained Markov decision processes formulation of the problem and linear programming algorithm to solve it and show that optimal schedulers are randomized in this case. In order to alleviate the computational complexity needed, to determine the optimal scheduling policy we propose a suboptimal log-scheduling policy that has performance close to that of the optimal scheduler. The proposed policy is also robust to different channel models. It is demonstrated that log-policy is favorable to the water-filling policy for very slow fading channels.

The multi-user MIMO space time scheduling problem is the prime focus of the paper. Optimizing the link level performance of the MIMO system does not always imply achieving scheduling level optimization. Therefore,design optimization across the link layer and the scheduling layer is very important to exploit fully the temporal and spatial dimensions of the communication channel. We address the design of the optimal space time scheduler for a multi-user MIMO system based on an information theoretical approach. We assume a partial feedback channel, namely a scaler rate-feedback channel, is available to the transmitter, but the full channel matrix is unknown to the transmitter. With the partial feedback, we find that the optimal resource allocation strategy is water-filling in both the temporal domain and spatial domain. The optimal scheduler should allocate all the power to at most n/sub R/ users at any particular instant. The optimal scheduler performance depends on the total number of users (K), the number of receive antennas at the base station (n/sub R/), and the number of transmit antennas at the mobile (n/sub T/). The scheduling gain increases with n/sub R/ due to the distributed MIMO configuration formed between mobile users and base station. With a single power feedback channel, the scheduling gain reduces as n/sub T/ increases, illustrating that transmit diversity hurts the scheduling performance in the case of scalar feedback. Finally, scheduling performance improves as K increases due to the multi-user selection diversity.

An exercise in formal specification and design of an asynchronous controller that leads to the CMOS implementation is presented. In this paper we focus on the formal specification of the controller by using communication sequential process, a tool based on Hoare's CSP. We also present the procedure, based on Martin's synthesis method, used to formally derive the preliminary design of the asynchronous traffic light controller. The formal specification and circuit implementation are formally verified with a verification tool package STTools, capable of model checking and simulating programs.

Cognitive network is a new approach to solve self-management of complex heterogeneous network, and its model and analysis method are key problems to be solved. a formal modeling and analysis method for cognitive network is proposed based on stochastic process algebra. Firstly, basic concept of PEPA is introduced. then system behaviors are abstracted combining with cognitive essence, and formal models for cognitive network are constructed from the angles of macroscopic operating states and internal services with PEPA respectively. on the basis, quantitative analysis method is discussed. the proposed modeling and analysis method has the features logical accuracy, which can apply in any phases and direct the designation of cognitive network.

The use of formal methods has long been advocated in the development of secure systems. Yet, methods for deriving design from requirements that guarantee retention of the intended security properties remain largely unrealized on a repeatable and consistent basis. We present the FADES (Formal Analysis and Design approach for Engineering Security) that integrates KAOS (Knowledge Acquisition in autOmated Specifications) with the B specification language to derive security design specifications and further implementation from security requirements. We demonstrate the capability of the approach to handle changes to security requirements by introducing corrective changes to the security requirements of a case study, the spy network system. The objective is to bridge the gap between formal requirements and design for security requirements. Our initial results show promise with FADES in preserving security properties and detecting security vulnerabilities early during requirements. Encouraged by these, we are more quantitatively assessing the FADES capabilities.

With high maneuverability and flexibility, aerial transportation by suspending the payload beneath the quadrotor is an ideal choice. To adapt more complex traffic conditions and extend the application scope of aerial transportation systems, the ability of payload hoisting/lowering is studied in this paper. The dynamic model is established by Lagrange's modeling method, and main characteristics are then analyzed based on the derived model. Subsequently, through an energy-based analysis method, we design a nonlinear controller for the corresponding system. By using Lyapunov techniques and LaSalle's invariance principle, the equilibrium point of the overall closed-loop system is proven to be asymptotically stable. Two groups of simulation are given to demonstrate the proposed control law's performance. Specifically, we compare the performance of the proposed system with the one with invariant rope length.

The main advantage of one-cycle control method is its ability to reject input disturbance in one-cycle. But despite of this great ability, it can not provide good responses in following commands and rejection of load disturbance. In this work, it is shown that it is possible to overcome these problems by the use of another controller. Although the idea of using output feedback has been used in previous works, the design of controller has become simpler in this work, by consideration of a simple model for one-cycle controller. In proposed method, difficult mathematical modeling is avoided. Based on decoupling of effects of feedback and input voltage disturbance, a simple model for one-cycle controller has been given. Therefore, by employing a conventional averaging method and the model of one-cycle controller, design of PID controller has become straightforward.

Present design processes for satellite networks mainly involve interconnected system models and their parameter-based simulations without emphasizing high level requirements in the process. What is missing is a systems engineering approach and a system of verification and validation based on formal representation and analysis. We propose a systems design methodology for inter-satellite communication based on the Responsive and Formal Design (RFD) [1]-[3], which addresses the need for a model-based system engineering approach coupled with a system of validation and verification based on formal representation and analysis. The goal is to apply the RFD process to provide a solution for the Inter-Satellite Communications (ISC) problem within the Open Systems Interconnection (OSI) framework. The OSI represents a standard framework for communication between devices. It divides the communication process into seven layers, with each one providing well-defined functions and services. We will address the integration of the RFD process with the OSI framework for ISC. The RFD process involves levels of design abstraction and refinement which correspond to layers or groups of layers of the OSI model. The process illustrates how the complete framework for ISC unfolds in an iterative manner.