Periodic Event Scheduling for Automated Production Systems

Consider optimizing a periodic schedule for an automated production plant as a last step of a more comprehensive design process. In our scenario, each robot’s cyclic sequence of operations and trajectories between potential waiting points have already been fully specified. Further given are those precedences that fix sequence requirements on operations between different robots. It remains to determine the starting time for each operation or movement of each robot within a common cyclic time period so as to avoid collisions of robots that operate in the same space simultaneously. So the task is to find a conflict-resolving schedule that minimizes this common periodic cycle time while observing all precedence relations and collision avoidance constraints. The proposed cycle time minimization problem for robot coordination has, to the best of our knowledge, not been studied before. We develop an approach for solving it by employing binary search for determining the smallest feasible period time of an iso-periodic event scheduling problem (IPESP). This is a variant of the periodic event scheduling problem in which the objects that have to be scheduled need to obey exactly the same period time. The possibility to wait arbitrarily long at waiting points turns out to be essential to justify the use of binary search for identifying the minimum cycle time, thereby avoiding bilinear mixed integer formulations. Special properties of the given scenario admit bounds on the periodic tension variables of an integer programming formulation. Although the IPESP subproblems remain NP-complete in general, these bounds allow solving real-world instances sufficiently fast for the approach to be applicable in practice. Numerical experiments on real-world and randomly generated data are supplied to illustrate the potential and limitations of this approach. Summary of Contribution: When designing automated production plants, a crucial step is to identify the smallest possible per unit period time for the production processes. Based on periodic event scheduling ideas, we develop and analyze mathematical methods for this purpose. We show that the algorithmic implementation of our approach provides an answer to current real-world designs in reasonable time.

Analyzing Isolation in Mobile Systems

As a safety-critical issue in complex mobile systems, isolation requires two or more mobile objects not to appear in the same place simultaneously. To ensure such isolation, a scheduling policy is needed to control and coordinate the movement of mobile objects. Unfortunately, existing task scheduling theories fails in providing effective solutions, because it is hardly possible to decompose a complex mobile system into multiple independent tasks. To solve this problem, a more fine-grained event scheduling is proposed in this paper to generate scheduling policies which can ensure the isolation of mobile objects. After defining event scheduling based on event-based formal models called dependency structures, a new event scheduling theory for mobile systems is developed accordingly. Then an algorithm for generating an event scheduling policy is proposed to implement the required isolation. Simulation experiments are conducted to prove the result of our theoretical analysis and show the effectiveness and scalability of the approach.

School Operational Effectiveness Analysis Web Based Event System with Dynamic Systems Development

<span>School institutions in Batam have problems in how the events they conduct can support the school's operational effectiveness. The solution model for these problems is to build web-based event systems using the dynamic systems development (DSDM) method. This system aims to solve problems that occur in event scheduling at activities carried out at school institutions in Batam. The school representative used is a school in Batam. The method is done by learning and the feasibility of case studies, model functionality, design, and implementation. This implementation produces a system that is very helpful in processing data and reports during the event. Starting from the registration of the event, the continuity of the event, until the completion of the event, all can be stored in detail. Besides users, there are also managers and administrators. Managers have a role to manage the data entered by registrants, while administrators give access to each user account and maintain system security. This system is divided into 2 roles with one as a user and one acting as an administrator. Registrants to participate in this event act as users. The results of this study are that school operational effectiveness increases after implementing this web-based event system.</span>

A Node-Oriented Discrete Event Scheduling Algorithm Based on Finite Resource Model

Discrete event simulation is the most important and essential part in network simulation. The node-oriented model of discrete event scheduling is a model that allocates computing resources as nodes and makes the discrete event simulation as a simulation task on nodes. In this article the reason of low performance in large-scale network simulation is analyzed, and an ideal node-oriented model of discrete event scheduling is presented and a resource-limited node-oriented model of discrete event scheduling by adding some restrictions on network resources is proposed. Then, the authors complete contrast experiments of the resource-limited node-oriented model of discrete event scheduling and NS2. Finally, packet loss in resource-limited node-oriented model of discrete event scheduling is examined. Also, NS2 is discussed in this article and the authors have proposed an improved method for the packet loss algorithm in a resource-limited node-oriented model of discrete event scheduling.

Modeling and Optimization for Collaborative Business Process Towards IoT Applications

The rapid development of Internet of Things (IoT) attracts growing attention from both industry and academia. IoT seamlessly connects the real world and cyberspace via various business process applications hosted on the IoT devices, especially on smart sensors. Due to the discrete distribution and complex sensing environment, multiple coordination patterns exist in the heterogeneous sensor networks, making modeling and analysis particularly difficult. In addition, massive sensing events need to be routed, forwarded and processed in the distributed execution environment. Therefore, the corresponding sensing event scheduling algorithm is highly desired. In this paper, we propose a novel modeling methodology and optimization algorithm for collaborative business process towards IoT applications. We initially extend the traditional Petri nets with sensing event factor. Then, the formal modeling specification is investigated and the existing coordination patterns, including event unicasting pattern, event broadcasting pattern, and service collaboration pattern, are defined. Next, we propose an optimization algorithm based on Dynamic Priority First Response (DPFR) to solve the problem of sensing event scheduling. Finally, the approach presented in this paper has been validated to be valid and implemented through an actual development system.