An FPTAS for parallel-machine scheduling under a grade of service provision to minimize makespan

Author name used in this publication: T. C. E. Cheng2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Scheduling with processing set restrictions : a survey

2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Scheduling parallel machines with inclusive processing set restrictions and job release times

2009-2010 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

A fast preemptive scheduling algorithm with release times and inclusive processing set restrictions

AbstractWe consider the problem of preemptively scheduling n independent jobs on m parallel machines so as to minimize the makespan. Each job Jj has a release time rj and it can only be processed on a subset of machines Mj. The machines are linearly ordered. Each job Jj has a machine index aj such that Mj={Maj,Maj+1,…,Mm}. We first show that there is no 1-competitive online algorithm for this problem. We then give an offline algorithm with a running time of O(nklogP+mnk2+m3k), where k is the number of distinct release times and P is the total processing time of all jobs

A Modeling and Analysis Framework To Support Monitoring, Assessment, and Control of Manufacturing Systems Using Hybrid Models

The manufacturing industry has constantly been challenged to improve productivity, adapt to continuous changes in demand, and reduce cost. The need for a competitive advantage has motivated research for new modeling and control strategies able to support reconfiguration considering the coupling between different aspects of plant floor operations. However, models of manufacturing systems usually capture the process flow and machine capabilities while neglecting the machine dynamics. The disjoint analysis of system-level interactions and machine-level dynamics limits the effectiveness of performance assessment and control strategies. This dissertation addresses the enhancement of productivity and adaptability of manufacturing systems by monitoring and controlling both the behavior of independent machines and their interactions. A novel control framework is introduced to support performance monitoring and decision making using real-time simulation, anomaly detection, and multi-objective optimization. The intellectual merit of this dissertation lies in (1) the development a mathematical framework to create hybrid models of both machines and systems capable of running in real-time, (2) the algorithms to improve anomaly detection and diagnosis using context-sensitive adaptive threshold limits combined with context-specific classification models, and (3) the construction of a simulation-based optimization strategy to support decision making considering the inherent trade-offs between productivity, quality, reliability, and energy usage. The result is a framework that transforms the state-of-the-art of manufacturing by enabling real-time performance monitoring, assessment, and control of plant floor operations. The control strategy aims to improve the productivity and sustainability of manufacturing systems using multi-objective optimization. The outcomes of this dissertation were implemented in an experimental testbed. Results demonstrate the potential to support maintenance actions, productivity analysis, and decision making in manufacturing systems. Furthermore, the proposed framework lays the foundation for a seamless integration of real systems and virtual models. The broader impact of this dissertation is the advancement of manufacturing science that is crucial to support economic growth. The implementation of the framework proposed in this dissertation can result in higher productivity, lower downtime, and energy savings. Although the project focuses on discrete manufacturing with a flow shop configuration, the control framework, modeling strategy, and optimization approach can be translated to job shop configurations or batch processes. Moreover, the algorithms and infrastructure implemented in the testbed at the University of Michigan can be integrated into automation and control products for wide availability.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147657/1/migsae_1.pd

Some combinational optimization problems on radio network communication and machine scheduling

The combinatorial optimization problems coming from two areas are studied in this dissertation: network communication and machine scheduling. In the network communication area, the complexity of distributed broadcasting and distributed gossiping is studied in the setting of random networks. Two different models are considered: one is random geometric networks, the main model used to study properties of sensor and ad-hoc networks, where ri points are randomly placed in a unit square and two points are connected by an edge if they are at most a certain fixed distance r from each other. The other model is the so-called line-of-sight networks, a new network model introduced recently by Frieze et al. (SODA\u2707). The nodes in this model are randomly placed (with probability p) on an n x n grid and a node can communicate with all the nodes that are in at most a certain fixed distance r and which are in the same row or column. It can be shown that in many scenarios of both models, the random structure of these networks makes it possible to perform distributed gossiping in asymptotically optimal time 0(D), where D is the diameter of the network. The simulation results show that most algorithms especially the randomized algorithm works very fast in practice. In the scheduling area, the first problem is online scheduling a set of equal processing time tasks with precedence constraints so as to minimize the makespan. It can be shown that Hu \u27s algorithm yields an asymptotic competitive ratio of 3/2 for intree precedence constraints and an asymptotic competitive ratio of 1 for outtree precedences, and Coffinan-Graham algorithm yields an asymptotic competitive ratio of 1 for arbitrary precedence constraints and two machines.The second scheduling problem is the integrated production and delivery scheduling with disjoint windows. In this problem, each job is associated with a time window, and a profit. A job must be finished within its time window to get the profit. The objective is to pick a set ofjobs and schedule them to get the maximum total profit. For a single machine and unit profit, an optimal algorithm is proposed. For a single machine and arbitrary profit, a fully polynomial time approximation scheme(FPTAS) is proposed. These algorithms can be extended to multiple machines with approximation ratio less than e/(e - 1). The third scheduling problem studied in this dissertation is the preemptive scheduling algorithms with nested and inclusive processing set restrictions. The objective is to minimize the makespan of the schedule. It can be shown that there is no optimal online algorithm even for the case of inclusive processing set. Then a linear time optimal algorithm is given for the case of nested processing set, where all jobs are available for processing at time t = 0. A more complicated algorithm with running time 0(n log ri) is given that produces not only optimal but also maximal schedules. When jobs have different release times, an optimal algorithm is given for the nested case and a faster optimal algorithm is given for the inclusive processing set case

Just-in-time Hardware generation for abstracted reconfigurable computing

This thesis addresses the use of reconfigurable hardware in computing platforms, in order to harness the performance benefits of dedicated hardware whilst maintaining the flexibility associated with software. Although the reconfigurable computing concept is not new, the low level nature of the supporting tools normally used, together with the consequent limited level of abstraction and resultant lack of backwards compatibility, has prevented the widespread adoption of this technology. In addition, bandwidth and architectural limitations, have seriously constrained the potential improvements in performance. A review of existing approaches and tools flows is conducted to highlight the current problems being faced in this field. The objective of the work presented in this thesis is to introduce a radically new approach to reconfigurable computing tool flows. The runtime based tool flow introduces complete abstraction between the application developer and the underlying hardware. This new technique eliminates the ease of use and backwards compatibility issues that have plagued the reconfigurable computing concept, and could pave the way for viable mainstream reconfigurable computing platforms. An easy to use, cycle accurate behavioural modelling system is also presented, which was used extensively during the early exploration of new concepts and architectures. Some performance improvements produced by the new reconfigurable computing tool flow, when applied to both a MIPS based embedded platform, and the Cray XDl, are also presented. These results are then analyzed and the hardware and software factors affecting the performance increases that were obtained are discussed, together with potential techniques that could be used to further increase the performance of the system. Lastly a heterogenous computing concept is proposed, in which, a computer system, containing multiple types of computational resource is envisaged, each having their own strengths and weaknesses (e.g. DSPs, CPUs, FPGAs). A revolutionary new method of fully exploiting the potential of such a system, whilst maintaining scalability, backwards compatibility, and ease of use is also presented

Komponenta projekta ADRICOSM – sustav promatranja na velikoj skali – satelitski sustav

In the framework of the ADRICOSM project, the Satellite Oceanography Group (GOS) of Rome developed a Fast Delivery System (FDS) for providing the partner modeling centres with remotelysensed ocean colour and sea surface temperature (SST) data. Data are processed, mapped and binned on the Adriatic Sea area in order to be assimilated into both ecosystem models and circulation models for ocean forecasting. Further technological improvements permitted the building and optimization of a system suitable for meeting the increasing demand for near-real-time ocean colour and SST products for applications in operational oceanography. Real-Time Images of SeaWiFS chlorophyll concentration, clouds/case I/case II water flags and true colour images are obtained by processing the satellite passes using climatological ancillary data. These images are provided daily through an ad hoc automatic system that processes the raw satellite data and makes it available on the web within an hour of satellite overpass acquisition. All of the images are stored in a gallery web archive organized in a calendar chart. Accurate chlorophyll maps for assimilation are produced in near real time (typically after 4 days) as soon as daily meteorological ancillary data are made available on the NASA website. Each chlorophyll map is flagged for clouds or other contamination factors using the corresponding 24 quality flag maps. This implies that case-2 waters and spurious atmospheric effects have been removed from the pigment data set. This final product is binned on the Adriatic model grid and made available for the ADRICOSM project on the GOS web site. NOAA/AVHRR data are also acquired by the GOS ground station in Rome and managed by the FDS from their reception up to their distribution. Daily SST maps of the Adriatic Sea binned over the AREG model grid at 1/16° resolution are distributed weekly in Near-Real-Time along with the daily SST maps of the eastern Mediterranean Sea delivered at 1/8° resolution to the MFSTEP project. Real-Time SST maps of the Adriatic Sea at 1km resolution are posted daily in GIF format on the GOS website.U okviru projekta ADRISOSM, GOS (Grupa za satelitsku oceanografiju) iz Rima razvila je Sustav za brzu isporuku FDS, snabdijevanje partnerskih centara za modeliranje satelitskim snimcima boje mora i tem-peraturnim podacima površine mora (SST). Podaci za Jadran su obrađeni, pretvoreni u grafičke produkte i digitalizirani kako bi se mogli asimilirati u model strujanja i model ekosistema, te koristiti oceanografskoj prognozi. Daljnja tehnološka poboljšanja su omogućila izgradnju i optimalizaciju sustava, zbog rastućih potreba za produktima boje mora i površinske temperature za različite primjene u operativnoj oceanografiji. Slike koncentracije klorofila od senzora SeaWiFS, slike oblaka te Case1 i Case2 oznake, kao i slike prave boje dobivaju se procesiranjem satelitskih scena uz popratne klimatološke podatke. Slike se procesiraju dnevno kroz ad-hoc automatski sustav koji obrađuje sirove satelitske podatke i omogućuje njihovu isporuku na mrežu, sat vremena nakon prikupljanja satelitskih podataka tj. nakon prolaska satelita. Sve se slike spremaju u arihvu na mreži koja je organizirana prema datumima. Korigirane slike koncentracije klorofila za asimilaciju u model proizvode se u skoro realnom vremenu (tipično 4 dana kasnije) čim se dobiju popratni meteorološki podaci s mreže NASA-e. Na svakoj slici klorofila su označeni oblaci ili drugi kontaminirajući faktori, prema 24 kategorije kvalitete slika. To znači da su Case 2 slučajevi piksela uklonjeni iz snimaka kao i atmosferske sme-tnje. Konačni produkt se usklađuje s koordinatnom mrežom Jadrana i stavlja na raspolaganje na stranicama ADRICOSM-a preko GOS-ove Internet stranice. GOS zemaljska stanica u Rimu prikuplja i podatke NOAA/ AVHRR koji se procesiraju kroz FDS sustav, od prijema do konačne distribucije podataka. Dnevne se slike površinske temperature mora (SST), usklađene preko koordinatne mreže AREG-a pri prostornom razlučivanju od 1/16 stupnja, distribuiraju tjedno u skoro realnom vremenu, zajedno sa slikama istočnog Sredozemlja koje imaju razlučivanje od 1/8 stupnja prema MFSTEP projektu. Dnevno, u skoro realnom vremenu, isporučuju se slike SST za Jadran uz prostorno razlučivanje od 1 km u GIF formatu na Internet stranici GOS-a