Browsing by Subject "Benchmarking"
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Item Open Access Analysis of reactive scheduling problems in a job shop environment(Elsevier, 2000) Sabuncuoğlu, İ.; Bayız, M.In this paper, we study the reactive scheduling problems in a stochastic manufacturing environment. Specifically, we test the several scheduling policies under machine breakdowns in a classical job shop system. In addition, we measure the effect of system size and type of work allocation (uniform and bottleneck) on the system performance. The performance of the system is measured for the mean tardiness and makespan criteria. We also investigate a partial scheduling scheme under both deterministic and stochastic environments for several system configurations.Item Open Access Capital maintenance as a key development tool(Wiley-Blackwell Publishing Ltd., 2010) Boucekkine, R.; Martinez, B.; Saglam, C.We construct optimal growth models where labor resources can be allocated either to production, technology adoption or capital maintenance. We first characterize the balanced growth paths of a benchmark model without maintenance. Then we introduce maintenance activity via the depreciation rate of capital. We characterize the optimal allocation of labor across the three activities. Although maintenance deepens the technological gap by diverting labor resources from adoption, we show that it generally increases the long run output level. Moreover, we find that equilibrium maintenance and adoption efforts respond in opposite directions to policy or technology shocks. Finally, we find that the long-term output response to policy shocks is slightly higher in the presence of maintenance. © 2010 The Authors. Scottish Journal of Political Economy © 2010 Scottish Economic Society.Item Open Access Fault-tolerant irregular topology design method for network-on-chips(IEEE, 2014) Tosun, S.; Ajabshir V.B.; Mercanoglu O.; Öztürk, ÖzcanAs the technology sizes of integrated circuits (ICs) scale down rapidly, current transistor densities on chips dramatically increase. While nanometer feature sizes allow denser chip designs in each technology generation, fabricated ICs become more susceptible to wear-outs, causing operation failure. Even a single link failure within an on-chip fabric can halt communication between application blocks, which makes the entire chip useless. In this study, we aim to make faulty chips designed with Network-on-Chip (NoC) communication usable. Specifically, we present a fault-tolerant irregular topology generation method for application specific NoC designs. Designed NoC topology allows a different routing path if there is a link failure on the default routing. We compare fault-tolerant topologies with regular fault-tolerant ring topologies, and non-fault-tolerant application specific irregular topologies on energy consumption, performance, and area using multimedia benchmarks and custom-generated graphs. © 2014 IEEE.Item Open Access Fault-tolerant topology generation method for application-specific network-on-chips(Institute of Electrical and Electronics Engineers, 2015) Tosun, S.; Ajabshir, V. B.; Mercanoglu, O.; Ozturk, O.As the technology sizes of integrated circuits (ICs) scale down rapidly, current transistor densities on chips dramatically increase. While nanometer feature sizes allow denser chip designs in each technology generation, fabricated ICs become more susceptible to wear-outs, causing operation failure. Even a single link failure within an on-chip fabric can halt communication between application blocks, which makes the entire chip useless. In this paper, we aim to make faulty chips designed with network-on-chip (NoC) communication usable. Specifically, we present fault-tolerant irregular topology-generation method for application-specific NoC designs. Designed NoC topology allows different routing path if there is a link failure on the default routing path. Additionally, we present a simulated annealing-based application mapping algorithm aiming to minimize total energy consumption of the NoC design. We compare fault-tolerant topologies with nonfault-tolerant application-specific irregular topologies on energy consumption, performance, and area using multimedia benchmarks and custom-generated graphs. Our results demonstrate that our method is able to determine fault-tolerant topologies with negligible area increase and better energy values.Item Open Access Graph aware caching policy for distributed graph stores(IEEE, 2015-03) Aksu, Hidayet; Canım, M.; Chang, Y.-C.; Körpeoğlu, İbrahim; Ulusoy, ÖzgürGraph stores are becoming increasingly popular among NOSQL applications seeking flexibility and heterogeneity in managing linked data. Conceptually and in practice, applications ranging from social networks, knowledge representations to Internet of things benefit from graph data stores built on a combination of relational and non-relational technologies aimed at desired performance characteristics. The most common data access pattern in querying graph stores is to traverse from a node to its neighboring nodes. This paper studies the impact of such traversal pattern to common data caching policies in a partitioned data environment where a big graph is distributed across servers in a cluster. We propose and evaluate a new graph aware caching policy designed to keep and evict nodes, edges and their metadata optimized for query traversal pattern. The algorithm distinguishes the topology of the graph as well as the latency of access to the graph nodes and neighbors. We implemented graph aware caching on a distributed data store Apache HBase in the Hadoop family. Performance evaluations showed up to 15x speedup on the benchmark datasets preferring our new graph aware policy over non-aware policies. We also show how to improve the performance of existing caching algorithms for distributed graphs by exploiting the topology information. © 2015 IEEE.Item Open Access Hypergraph-theoretic partitioning models for parallel web crawling(Springer, London, 2012) Türk, Ata; Cambazoğlu, B. Barla; Aykanat, CevdetParallel web crawling is an important technique employed by large-scale search engines for content acquisition. A commonly used inter-processor coordination scheme in parallel crawling systems is the link exchange scheme, where discovered links are communicated between processors. This scheme can attain the coverage and quality level of a serial crawler while avoiding redundant crawling of pages by different processors. The main problem in the exchange scheme is the high inter-processor communication overhead. In this work, we propose a hypergraph model that reduces the communication overhead associated with link exchange operations in parallel web crawling systems by intelligent assignment of sites to processors. Our hypergraph model can correctly capture and minimize the number of network messages exchanged between crawlers. We evaluate the performance of our models on four benchmark datasets. Compared to the traditional hash-based assignment approach, significant performance improvements are observed in reducing the inter-processor communication overhead. © 2012 Springer-Verlag London Limited.Item Open Access ISO 9000 implementation in Turkish industry(Emerald, 1997) Erel, E.; Ghosh, J. B.Notes that it has become a competitive necessity for firms doing business globally to acquire the ISO 9000 certification, despite the misgivings many have with regard to its true effectiveness. Turkey, an emerging industrial economy, has a significant stake in the EU markets. At present, there is no systematic study documenting the status of ISO 9000 implementation in Turkey, the profile of the certified firms, their motivation, and their organizational experience during and after the certification process; whereas such studies have begun to emerge in other countries. Provides a background on the Turkish quality movement, and reports the results of a survey conducted among large Turkish companies that attempts to provide answers to the issues raised above. The findings are revealing and should help an international manager doing or planning to do business in Turkey, or his Turkish counterpart thinking about getting certification.Item Open Access Moving shadow detection in video using cepstrum(SAGE, 2013) Cogun, F.; Çetin, A. EnisMoving shadows constitute problems in various applications such as image segmentation and object tracking. The main cause of these problems is the misclassification of the shadow pixels as target pixels. Therefore, the use of an accurate and reliable shadow detection method is essential to realize intelligent video processing applications. In this paper, a cepstrum-based method for moving shadow detection is presented. The proposed method is tested on outdoor and indoor video sequences using well-known benchmark test sets. To show the improvements over previous approaches, quantitative metrics are introduced and comparisons based on these metrics are made. © 2013 Cogun and Cetin; licensee InTech.Item Open Access Optimal and suboptimal receivers for code-multiplexed transmitted-reference ultra-wideband systems(Wiley, 2013) Tutay, M. E.; Gezici, SinanIn this study, optimal and suboptimal receivers are investigated for code-multiplexed transmitted-reference (CM-TR) ultra-wideband systems. First, a single-user scenario is considered, and a CM-TR system is modeled as a generalized noncoherent pulse-position modulated system. Based on that model, the optimal receiver that minimizes the bit error probability is derived. Then, it is shown that the conventional CM-TR receiver converges to the optimal receiver under certain conditions and achieves close-to-optimal performance in practical cases. Next, multi-user systems are considered, and the conventional receiver, blinking receiver, and chip discriminator are investigated. Also, the linear minimum mean-squared error (MMSE) receiver is derived for the downlink of a multi-user CM-TR system. In addition, the maximum likelihood receiver is obtained as a performance benchmark. The practicality and the computational complexity of the receivers are discussed, and their performance is evaluated via simulations. The linear MMSE receiver is observed to provide the best trade-off between performance and complexity/practicality.Item Open Access Physical optics modeling of 2D dielectric lenses(Optical Society of America, 2009-01-27) Yurchenko, V. B.; Altintas, A.We propose an advanced physical optics formulation for the accurate modeling of dielectric lenses used in quasi-optical systems of millimeter, submillimeter, and infrared wave applications. For comparison, we obtain an exact full-wave solution of a two-dimensional lens problem and use it as a benchmark for testing and validation of asymptotic models being considered.Item Open Access Strategic alignment and new product development: drivers and performance effects(Wiley-Blackwell Publishing, 2012) Acur, N.; Kandemir, D.; Boer H.Strategic alignment is widely accepted as a prerequisite for a firm's success, but insight into the role of alignment in, and its impact on, the new product development (NPD) process and its performance is less well developed. Most publications on this topic either focus on one form of alignment or on one or a limited set of NPD performance indicators. Furthermore, different and occasionally contradictory findings have been reported. NPD scholars have long argued for the importance of fit between context and NPD activities. However, this body of literature suffers from the same weakness: most publications have a limited scope and the findings are not always consistent with results reported previously. This study addresses these deficiencies by examining (1) the effects of various internal and external factors on different forms of alignment, and (2) the effects of these forms of alignment on a set of NPD performance indicators. Strategic planning and innovativeness appear to affect technological, market, and NPD-marketing alignment positively. Environmental munificence is negatively associated with NPD-marketing alignment, but has no effect on the two other forms of alignment. Technological change has a positive effect on technological alignment, a negative effect on NPD-marketing alignment, but no effect on market alignment. These findings suggest that internal capabilities are more likely to be associated with the development of strategic alignment than environmental factors are. Furthermore, technological and NPD-marketing alignment affect NPD performance positively, while market alignment does not have any significant performance effects.Item Open Access Structuring research on conformal antennas a European collaboration(Institution of Engineering and Technology, 2007) Sipus, Z.; Persson, P.; Lanne, M.; Heckler, M.; Maci, S.; Masa-Campos, J. L.; Knott, P.; Ertürk, Vakur B.; Vandenbosch, G.The topic of this paper is the work carried out within work package 2.4-3 of the EU network "antenna centre of excellence" (ACE). This work package is concerned with structuring research on conformal antennas. In particular, the work is focused on the problems associated with full benchmarking of conformal antennas, on development of hybrid programs for analyzing different classes of conformal antennas, and on investigation of properties of algorithms for optimizing beam synthesis and beam-steering for conformal arrays.Item Open Access Sulfur-tolerant BaO/ZrO2/TiO2/Al2O3 quaternary mixed oxides for deNOX catalysis(Royal Society of Chemistry, 2017) Say, Z.; Mihai, O.; Tohumeken, M.; Ercan, K. E.; Olsson, L.; Ozensoy, E.Advanced quaternary mixed oxide materials in the form of BaO/Al2O3/ZrO2/TiO2 functionalized with Pt active sites (i.e. Pt/BaO/AZT) were synthesized and structurally characterized via XRD and BET in comparison to a conventional Pt/20BaO/Al benchmark NSR/LNT catalyst. The interactions of these catalysts' surfaces with SOx and NOx gases were monitored via in situ FTIR and TPD. There exists a delicate trade-off between NOx storage capacity (NSC) and sulfur uptake/poisoning which is strongly governed by the BaO loading/ dispersion as well as the surface structure and acidity of the support material. Flow reactor measurements performed under realistic catalytic conditions show the high NOx activity for the Pt/20BaO/AZT catalyst at 573 K. After sulfur poisoning and subsequent regeneration at 773 and 973 K, Pt/20BaO/AZT surpassed the NOx catalytic performance at 573 K of all other investigated materials including the conventional Pt/ 20BaO/Al benchmark catalyst.Item Open Access Throughput modeling of single hop CSMA networks with non-negligible propagation delay(IEEE, 2013) Koseoglu, M.; Karasan, E.We analyze the performance of the CSMA protocol under propagation delays that are comparable with packet transmission times. We propose a semi-Markov model for the 2-node CSMA channel. For the 2-node case, the capacity reduces to 40% of the zero-delay capacity when the one-way propagation delay is 10% of the packet transmission time. We then extend this model and obtain the optimum symmetric probing rate that achieves the maximum network throughput as a function of the average propagation delay, d, and the number of nodes sharing the channel, N. The proposed model predicts that the total capacity decreases with d-1 as N goes to infinity when all nodes probe the channel at the optimum rate. The optimum probing rate for each node decreases with 1/N and the total optimum probing rate decreases faster than d-1 as N goes to infinity. We investigate how the short-term unfairness problem in CSMA worsens as the propagation delay increases and propose a back-off mechanism to mitigate this issue. The theoretical results presented in this paper can be used as a benchmark for the performance improvements provided by algorithms that have already been developed.