Derandomization of Online Assignment Algorithms for Dynamic Graphs

This paper analyzes different online algorithms for the problem of assigning weights to edges in a fully-connected bipartite graph that minimizes the overall cost while satisfying constraints. Edges in this graph may disappear and reappear over time. Performance of these algorithms is measured using simulations. This paper also attempts to derandomize the randomized online algorithm for this problem

Provably Efficient Adaptive Scheduling for Parallel Jobs

Scheduling competing jobs on multiprocessors has always been an important issue for parallel and distributed systems. The challenge is to ensure global, system-wide efficiency while offering a level of fairness to user jobs. Various degrees of successes have been achieved over the years. However, few existing schemes address both efficiency and fairness over a wide range of work loads. Moreover, in order to obtain analytical results, most of them require prior information about jobs, which may be difficult to obtain in real applications. This paper presents two novel adaptive scheduling algorithms -- GRAD for centralized scheduling, and WRAD for distributed scheduling. Both GRAD and WRAD ensure fair allocation under all levels of workload, and they offer provable efficiency without requiring prior information of job's parallelism. Moreover, they provide effective control over the scheduling overhead and ensure efficient utilization of processors. To the best of our knowledge, they are the first non-clairvoyant scheduling algorithms that offer such guarantees. We also believe that our new approach of resource request-allotment protocol deserves further exploration. Specifically, both GRAD and WRAD are O(1)-competitive with respect to mean response time for batched jobs, and O(1)-competitive with respect to makespan for non-batched jobs with arbitrary release times. The simulation results show that, for non-batched jobs, the makespan produced by GRAD is no more than 1.39 times of the optimal on average and it never exceeds 4.5 times. For batched jobs, the mean response time produced by GRAD is no more than 2.37 times of the optimal on average, and it never exceeds 5.5 times.Singapore-MIT Alliance (SMA

A New Competitive Ratio for Network Applications with Hard Performance Guarantee

Online algorithms are used to solve the problems which need to make decisions without future knowledge. Competitive ratio is used to evaluate the performance of an online algorithm. This ratio is the worst-case ratio between the performance of the online algorithm and the offline optimal algorithm. However, the competitive ratios in many current studies are relatively low and thus cannot satisfy the need of the customers in practical applications. To provide a better service, a practice for service provider is to add more redundancy to the system. Thus we have a new problem which is to quantify the relation between the amount of increased redundancy and the system performance. In this dissertation, to address the problem that the competitive ratio is not satisfactory, we ask the question: How much redundancy should be increased to fulfill certain performance guarantee? Based on this question, we will define a new competitive ratio showing the relation between the system redundancy and performance of online algorithm compared to offline algorithm. We will study three applications in network applications. We propose online algorithms to solve the problems and study the competitive ratio. To evaluate the performances, we further study the optimal online algorithms and some other commonly used algorithms as comparison. We first study the application of online scheduling for delay-constrained mobile offloading. WiFi offloading, where mobile users opportunistically obtain data through WiFi rather than through cellular networks, is a promising technique to greatly improve spectrum efficiency and reduce cellular network congestion. We consider a system where the service provider deploys multiple WiFi hotspots to offload mobile traffic with unpredictable mobile users’ movements. Then we study online job allocation with hard allocation ratio requirement. We consider that jobs of various types arrive in some unpredictable pattern and the system is required to allocate a certain ratio of jobs. We then aim to find the minimum capacity needed to meet a given allocation ratio requirement. Third, we study online routing in multi-hop network with end-to-end deadline. We propose reliable online algorithms to schedule packets with unpredictable arriving information and stringent end-to-end deadline in the network

pTNoC: Probabilistically time-analyzable tree-based NoC for mixed-criticality systems

The use of networks-on-chip (NoC) in real-time safety-critical multicore systems challenges deriving tight worst-case execution time (WCET) estimates. This is due to the complexities in tightly upper-bounding the contention in the access to the NoC among running tasks. Probabilistic Timing Analysis (PTA) is a powerful approach to derive WCET estimates on relatively complex processors. However, so far it has only been tested on small multicores comprising an on-chip bus as communication means, which intrinsically does not scale to high core counts. In this paper we propose pTNoC, a new tree-based NoC design compatible with PTA requirements and delivering scalability towards medium/large core counts. pTNoC provides tight WCET estimates by means of asymmetric bandwidth guarantees for mixed-criticality systems with negligible impact on average performance. Finally, our implementation results show the reduced area and power costs of the pTNoC.The research leading to these results has received funding from the European Community’s Seventh Framework Programme [FP7/2007-2013] under the PROXIMA Project (www.proxima-project.eu), grant agreement no 611085. This work has also been partially supported by the Spanish Ministry of Science and Innovation under grant TIN2015-65316-P and the HiPEAC Network of Excellence. Mladen Slijepcevic is funded by the Obra Social Fundación la Caixa under grant Doctorado “la Caixa” - Severo Ochoa. Carles Hern´andez is jointly funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER funds through grant TIN2014-60404-JIN. Jaume Abella has been partially supported by the MINECO under Ramon y Cajal postdoctoral fellowship number RYC-2013-14717.Peer ReviewedPostprint (author's final draft

Collective bargaining, decentralisation and crisis management in the German metalworking industries since 1990

Collective bargaining in the German metal and electrical engineering (M+E) industries has undergone a phase of considerable development since the 1990s. The profound changes which underwent collective bargaining in M+E over the last two decades have to be regarded against the background of a new global and national political and economic environment which emerged after the end of the Cold War. The M+E sector with at its core the automobile industry underwent successive waves of restructuring which shaped the bargaining agenda. This discussion paper examines these developments, putting a special focus on the changing bargaining agendas at both sectoral and company level and looks in particular at the decentralisation of collective bargaining. The management of the crisis of 2008 - 2010 in metal manufacturing is a further topic.A first version of this paper was presented at a meeting of the European GUSTO research project on 6 September 2011 in Barcelona. -- Die Tarifpolitik in der deutschen Metall- und Elektroindustrie hat seit den 1990er Jahren einen tief greifenden Wandel durchlaufen. Die Entwicklung der letzten zwei Jahrzehnte ist vor dem Hintergrund der Veränderungen in den globalen wie nationalen politischen und ökonomischen Rahmenbedingungen zu betrachten, die sich nach dem Ende des Kalten Krieges herausbildeten. Die Metall- und Elektroindustrie und insbesondere die Automobilindustrie erlebten aufeinander folgende Restrukturierungswellen, die die Inhalte der tariflichen und betrieblichen Aushandlungsprozesse prägten. Dieses Diskussionspapier untersucht diese Entwicklungen und die Veränderungen in der Betriebs- und Tarifpolitik, wobei besonders die Dezentralisierung der Tarifpolitik betrachtet wird. Das Krisenmanagement der Jahre 2008 bis 2010 in der Metall- und Elektroindustrie ist ein weiterer Punkt.Eine erste Version dieses Papier wurde am 6. September 2011 bei einem Treffen des europäischen GUSTO Forschungsprojekts in Barcelona vorgestellt.

Mission scheduler for a rail guided vehicle system

A transport system with automatic guided vehicles AGVs, is a fully automatic system that provides logistics services in industrial environments such as warehouses and production plants. These systems have reached such a degree of maturity as to allow, in their daily use, the application of heuristic algorithms for the optimization of the various operations they perform. For instance, find the shortest paths between working stations and storage area, assign movements and strategic positions for idle vehicles, operate efficient and long-life battery management and more. A relevant interesting algorithm, presented and developed in this thesis, concerns the sorting of products in the shipping phase, which affects the scheduling tasks assigned to the autonomous vehicles. The scheduler has the aims of determining which operations have more strict constraints and more priority over others. Studies and practice have shown that the adoption of a valid scheduler implies considerable improvements in the system performance, consequently it is advisable to dedicate time and effort to the research for the right one. The following algorithms obtained a successful outcome and they have been implemented for the production of a modern automated warehouse located in the city of Cesena, Italy. The paper is divided into four chapters, with a further one dedicated to conclusions