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The specifics of process manufacturing have a great influence on a production management and the focus of production scheduling is to maintain stable production within given constraints. The paper presents a dedicated online algorithm that has been developed with the intention of predicting the adequate starting time for a single new batch in a system consisting of two chemical reactors sharing a...
The foundation fieldbus specification is a technology that allows to construct control strategies in terms of blocks diagrams, distributed among the field devices on the network. First, the control engineer defines the control strategy to be used and then it is done the allocation (in the different field devices on the network) of the function blocks used in the defined strategy. After these allocation...
Shop floor controls have recently become fundamental for production controllers and industrial engineers, to apply scheduling and dispatching policies in the highly competitive semiconductor industry. Despite the emphasis put on shop floor scheduling techniques, the impact on the actual operations of the fab may not reflect controllers' expectations. We have developed a framework which provides them...
In-vehicle embedded systems typically consist of a set of nodes exchanging applicative data ("signals") through a stack of communication protocols that includes a middleware layer. On each node, tasks, both applicative and middleware level, are subject to deadline constraints. Furthermore, signals must be produced sufficiently recently for being safely consumed on the receiver end (so-called...
This paper compares the fieldbus protocols LIN 1.3, LIN 2.07 and TTP/A to the requirements of low-cost body electronic networks in the automotive domain. The examined protocols all aim at distributed smart sensor/actuator networks and provide support for low-cost implementation on standard microcontroller nodes. LIN comes with a rigid specification of the physical layer in order to support interoperability...
This work presents constraint programming (CP) approach applied to determine deadlock-free schedules in concurrent production processes. The rules of resource conflict resolution have been expressed by means of a set of predicates, which define constraints for the problem decisive variables. Predicate model has been defined in time and event domains and implemented in procedures of propagating and...
Industrial communication systems (ICS) are specifically designed for deterministic communication between sensors, actuators, programmable logic controllers, monitoring systems, and operator workstations. These networks are traditionally based on wired technology and a deterministic medium access control. Nowadays, the emerging trend is the availability of wireless technology for ICS, since this leads...
The maintenance of systems involved in production processes must be carried out with maximum efficiency and minimum downtime, especially on time-critical systems (operation times are included between a minimum and a maximum value). This paper presents a proactive/reactive control to fit preventive maintenance into a busy production schedule. As preventive maintenance is regarded as a non-preemptive...
This paper describes the hardware/software co-design of a multithreaded RTOS kernel on a new Xilinx Virtex II Pro FPGA. Our multithreaded RTOS kernel is an integral part of our hybrid thread programming model being developed for hybrid systems which are comprised of both software resident and hardware resident concurrently executing threads. Additionally, we provide new interrupt semantics by migrating...
In this paper we propose a system architecture that supports end-to-end scheduling of the distributed real-time thread abstraction. The real-time specification for Java (RTSJ) is used for the implementation of distributed real-time threads. By using simulations, we conclude that the proposed architecture is flexible enough to accommodate different scheduling algorithms
Due to the widespread availability of the Internet, large scale distributed projects in manufacturing are becoming popular. Besides resource constraints, there exist precedence constraints among activities within each project. This paper presents a hybrid genetic algorithm to solve the resource-constrained multi-project scheduling problem (RCMPSP), which is well known NP-hard problem. Objectives described...
There are several (not only industrial) applications which can tolerate some losses. A concise way to distinguish between allowed and forbidden loss patterns are (m,k)-firm deadlines, which state that at most m out of k consecutive packets may get lost. An obstacle to the fulfillment of even the relaxed (m,k)-firm deadlines are channel errors. In this paper we consider the case where multiple periodic...
Time-triggered systems are advantageous for embedded applications, when determinism, hard real-time behavior, and a straightforward way for certification are required. However, when it comes to flexibility, time-triggered systems often require that possible extensions have been planned in advance, which makes it difficult to apply unforeseen changes to such a system. This paper presents an approach...
In real-time systems, schedulability is mandatory but other application-dependent performance criteria are most generally of interest. We first define the properties that a "good" real-time scheduling algorithm must possess. Then, we exhibit a class of easily-implementable policies that should be well suited to various applicative contexts because, in our experiments, these policies provide...
This paper describes an open loop control method of the solder joint process in a rework station for faulty printed circuit board (PCBs) containing electronic components in packages ball grid arrays (BGAs). In particular, a mathematical model describing the solder joint process is, first of all, obtained. Then, the desired thermal profile of the junctions BGA-PCB is determined according to the physical...
In many digital control applications, data acquisition and process control are time-critical actions, assumed to be instantaneous and strictly periodic. However, aspects related to real-time scheduling algorithms may postpone the task execution and, consequently, delay the data acquisition and process control. We consider the acquired data from sensors as valid if acquired inside a time-interval that...
In this paper a mathematical model and a solution for the pump scheduling problem based on genetic algorithms is presented. The main objective is the reduction of the electricity costs of the water department for the pumping effort. The constraints are such as to maintain strategic security and reliability limits for each water reservoir. The reduction of the peaks during a scheduling period is equivalent...
Today there is a significant body of results of resource management in real-time systems. However, most of them are based on "open-loop" strategies and techniques that do not take into account application demands to dynamically adjust their behavior. To overcome this problem by focusing on control applications, we show a novel scheduling technique: large error first (LEF). This scheduling...
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