Performance Estimation with Automatic False-Path Detection for System-Level Designs

Negotiations were introduced in [6] as a model for concurrent systems with multiparty decisions. What is very appealing with negotiations is that it is one of the very few non-trivial concurrent models where several interesting problems, such as soundness, i.e. absence of deadlocks, can be solved in PTIME [3]. In this paper, we introduce the model of timed negotiations and consider the problem of computing the minimum and the maximum execution times of a negotiation. The latter can be solved using the algorithm of [10] computing costs in negotiations, but surprisingly minimum execution time cannot.This paper proposes new algorithms to compute both minimum and maximum execution time, that work in much more general classes of negotiations than [10], that only considered sound and deterministic negotiations. Further, we uncover the precise complexities of these questions, ranging from PTIME to varDelta _2^P-complete. In particular, we show that computing the minimum execution time is more complex than computing the maximum execution time in most classes of negotiations we consider.

The application scheduling is an important requirement in the cloud computing context. It allows to define the required resources to execute applications tasks following predefined criteria, for instance, maximum execution time, number of virtual machines, volume of data, among others. Selecting process to choose the most appropriate execution structure is driven by scheduling algorithms. This paper proposes a scheduling mechanism for data processing in cloud computing environments. Such mechanism analyzes some specific variables in the business context of a software house specialized in software for lawyers and law offices. The main goal of this mechanism is to fulfill the seasonal company's demand using IaaS services and considering two policies: (i) the maximum execution time allowed by the application may not be exceeded and (ii) the data have to be processed considering the lowest possible monetary cost. The proposed solution generates strategies to select the best set of virtual machines to process the current bunch of data considering the amount of data, the estimated execution time for each specific strategy and the monetary cost of the virtual machines sets. In the context of this work, the strategy concept means the schedule of a set of virtual machines to process a specific amount of data, load balancing decisions and the parallelism of application's execution flow. The proposed solution has resulted in great impact for that company since it allowed the vertiginous increase of the amount of clients served.

In this paper we consider the problem of designing controllers for linear plants to be implemented in embedded platforms under stringent real-time constraints. These include preemptive scheduling schemes, under which the maximum execution time allowed for control software tasks is uncertain. We propose an “anytime control” design approach, consisting in a hierarchy of controllers for the same plant. Higher controllers in the hierarchy provide better closed-loop performance, while typically requiring a larger worst-case execution time. We provide a procedure for the design of controllers which, together with a conditioning process of the stochastic scheduling, provides better performance than prevailing worst case-based design, while guaranteeing almost sure stability of the resulting switching system.KeywordsRoot Mean Square ErrorRoot Mean SquareClose Loop SystemBalance TruncationStochastic ScheduleThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

PREEMPTIVE AND NON-PREEMPTIVE REAL-TIME SCHEDULING BASED ON NEURAL NETWORKS

One of the major goals of the Service Oriented Architecture is to support automatic Web Service (WS) composition and execution, allowing a user query to be satisfied by a Composite WS (CWS). User queries express functional and non-functional (QoS) requirements. QoS requirements indicate, for example, the maximum execution time or price allowed for a CWS execution. In this work, we propose a model to support CWS executions while maintaining the QoS requirements, even in presence of failures. QoS monitoring is performed during the entire execution of a CWS in order to satisfy QoS requirements, influencing the choice of the fault-tolerance strategy selection in case of failures.

This study estimated availability of an air compression system and a nitrogen generation system in liquefied natural gas—floating production storage and offloading unit (LNG-FPSO) with different design stages to investigate the gap between the availability at the early design stage and that at the late design stage. Although availability estimation in the early design stage is more important than the late design stage, it is difficult to estimate the availability accurately in the early design stage. The design stage was divided into three depending on the design progress. Monte Carlo simulation technique was employed for the availability estimation. The results of the availability estimation showed that there was 0.434% difference between the early and late design stages. This meant that the availability in the early design stage was underestimated due to limited information. A sensitivity analysis was performed to investigate critical factors affecting the results. The investigated factors were failure rate, repair time, redundant equipment, and modified preventive maintenance schedule. The most critical factor was redundant equipment. It increased 0.486% availability.

Effective design collaboration during the early design stages in architecture is a condition for effective overall design and construction. This can be facilitated, supported and promoted through visual technological means. Collaborative design protocols implemented within the engineering fields (electrical and mechanical) can be adapted to the built environment design with emerging augmented reality technologies being the enablers for that shift. Architectural design requires a strongly visual approach to communication and means through which multiple disciples can collaborate effectively. Therefore, the aim of the research is to investigate principles and protocols to assist early design stage collaborative design among multidisciplinary teams, through visual and tactile user interfaces. This paper explores the current paradigm in AEC (architecture, engineering and construction), design collaboration and multidisciplinary group dynamics during the early design and conceptual stages in architecture. Afterwards, a design protocol is suggested, literature review regarding collaborative design and design protocols is summarized and further research is proposed on optimization and standardization of early design collaborative design in AEC.

Scheduling and resource allocation problems require numerous constraints and objectives. Latency constraints and network parameters have to be considered explicitly to produce realistic scheduling schemes. Finding an optimum scheduling algorithm is classified in the category of NP-Hard problems. Therefore, heuristic approaches are used to produce near optimal solutions with a variety of configurations. The heuristic approach presented in this paper is formulated in the framework of graph theory considering a processor network composed of a bounded number of non identical parallel processors. Every processor is able to execute only one, specific subset of tasks, having enough memory to store the communication data. The starting procedure of the algorithm uses a depth first search to find the set of all paths from source to sink. The principle procedure creates combinations of processors and task paths, seeking to allocate sets of adjacent tasks to the same compatible processor. Task selection is based on the maximum total execution time by simultaneously reducing the processor's idle time. The paper ends with a small detailed numerical example.

This paper presents techniques to integrate worst-case execution time (WCET) data into a compiler. Currently, a tight integration of WCET into compilers is strongly desired, but only some ad-hoc approaches were reported currently. Previous work mainly used self-written WCET estimators with limited functionality and preciseness during compilation. A very tight integration of a high quality WCET analyzer into a compiler was not yet achieved. This work is the first to present such a tight coupling between a compiler and the WCET analyzer aiT. This is done by automatically translating the assembly-like contents of the compiler's low-level format (LLIR) to aiT's exchange format CRL2. Additionally, the results produced by aiT are automatically collected and re-imported into the compiler infrastructure. The work described in this paper is smoothly integrated into a C compiler for the Infineon TriCore processor. It opens up new possibilities for the design of WCET-aware optimizations in the future. The concepts for extending the compiler structure are kept very general so that they are not limited to WCET information. Rather, it is possible to use our concepts also for multi-objective optimization of e. g. best-case execution time (BCET) or energy dissipation

In this paper an improvement of the schedulability analysis for fixed-priority distributed hard real-time systems is presented. During the analysis it is not sufficient to include the tasks’ worst-case execution time, but also the best-case execution time has to be considered, because the lower bound of the execution has a direct impact on the event densities in the system. The presented approach improves the best-case response time analysis introduced by Redell et al. The paper shows how it is possible to calculate a lower bound for the best-case response time using an expressive event model. This new lower bound of the response time will relax the event densities in a distributed system and will therefore lead to more relaxed worst-case response times.

Supplier involvement in automotive component design: are there really large US Japan differences?

Design for energy efficiency in early stages: A top-down method for new product development

Life Cycle Assessment (LCA) is used and accepted as a method to assess environmental impacts and resource use of buildings. In practice, LCA is typically used in stages where the design of the building is already finalized. However, LCA-calculations from early design stages can be used actively in design and optimization of the building. One of the obstacles to early stage LCA is that extensive data input on precise material types and amounts is needed, which is limited in early design stages. The simplifications needed for a designer in an early design LCA is addressed in a research project, where an extensive library of predefined building components and installations were developed and integrated into the existing Danish LCAbyg tool. The library assists the user in establishing a full building inventory by simple inputs of geometry of the building and a selection from the library of building element layers. However, the simplified approach to LCA of a building at early design stages inevitably affects results compared with results of a calculation made at later design stages where more, specific data is available. This paper presents an evaluation of building cases, modelled with the same background database and life cycle stages, using the simplified early design LCA approach and a detailed LCA approach. The evaluation includes testing of how well the predefined components in the early design approach fit with the case buildings and comparisons of the total material input and precision of the final LCA results.

In most of automobile body panel manufacturing, trimming process is generally performed before flanging. To find feasible trimming line is crucial in obtaining accurate edge profile after flanging. Section-based method develops blank along manually chosen section planes and find trimming line by generating loop of end points. This method suffers from inaccurate results of edge profile. On the other hand, simulation-based method can produce more accurate trimming line by iterative strategy. In this study, new fast simulation-based method to find feasible trimming line is proposed. Finite element inverse method is used to analyze the flanging process because final shape after flanging can be explicitly defined and most of strain paths are simple in flanging. In utilizing finite element inverse method, the main obstacle is the initial guess generation for general mesh. Robust initial guess generation method is developed to handle genera] mesh with very different size and undercut. The new method develops final triangular mesh incrementally onto the drawing tool surface. Also in order to remedy mesh distortion during development, energy minimization technique is utilized. Trimming line is extracted from the outer boundary after finite element inverse method simulation. This method has many advantages since trimming line can be obtained in the early design stage. The developed method is verified by shrink/stretch flange forming and successfully applied to the complex industrial applications such as door outer flanging process.

Detailed simulation of buildings’ thermal performance can provide useful information for building designers and engineers. However, deployment of detailed simulation involves a number of challenges, including time and effort expenditures not accounted for in many typical building delivery processes. In this context, careful application of simplified methods may provide – at least for a specific class of applications – a reasonable alternative. The present contribution explores this possibility via a specific case study involving a large sample of residential buildings in Gaza, Palestine. This sample includes some fifty multi-unit apartment buildings representing the bulk of residential building stock in Gaza. These buildings were subjected to computational cooling energy demand assessment, whereby both numeric simulation and derivative simplified methods were applied. Numeric simulations were performed using EnergyPlus. For simplified calculations, a regression-based procedure was derived. Toward this end, a number of candidate independent variables (e.g., compactness, effective window-to-wall ration, LEK value, mean effective U-value) were considered and the level of their association with the computed values of the designated building performance indicators was observed. The comparison of the results of the simplified and simulation-based methods revealed a reasonable level of agreement. In other words, the application of the simplified method provides in the majority of the cases performance indicator values that are close enough to the corresponding results of the simulation-based method. This implies that simplified methods and associated prescriptive procedures may provide an attractive alternative to highly detailed simulation studies in cases were the paucity of information and/or computational resources may represent a challenge (e.g., early design stages, insufficient preparedness of the professional community, contextual constraints).