3,359 research outputs found

    CloudScope: diagnosing and managing performance interference in multi-tenant clouds

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    © 2015 IEEE.Virtual machine consolidation is attractive in cloud computing platforms for several reasons including reduced infrastructure costs, lower energy consumption and ease of management. However, the interference between co-resident workloads caused by virtualization can violate the service level objectives (SLOs) that the cloud platform guarantees. Existing solutions to minimize interference between virtual machines (VMs) are mostly based on comprehensive micro-benchmarks or online training which makes them computationally intensive. In this paper, we present CloudScope, a system for diagnosing interference for multi-tenant cloud systems in a lightweight way. CloudScope employs a discrete-time Markov Chain model for the online prediction of performance interference of co-resident VMs. It uses the results to optimally (re)assign VMs to physical machines and to optimize the hypervisor configuration, e.g. the CPU share it can use, for different workloads. We have implemented CloudScope on top of the Xen hypervisor and conducted experiments using a set of CPU, disk, and network intensive workloads and a real system (MapReduce). Our results show that CloudScope interference prediction achieves an average error of 9%. The interference-aware scheduler improves VM performance by up to 10% compared to the default scheduler. In addition, the hypervisor reconfiguration can improve network throughput by up to 30%

    Application of the UKCP09 WG Outputs to Assess Performance of Combined Sewers System in a Changing Climate

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    In many parts of the world old sewer systems have been designed without consideration for change in climate, so probabilities and risks of sewer surcharge and flooding are elevated due to increase in extreme rainfall events as a consequence of global warming. The current paper is aiming to assess how the climate change on interannual to multidecadal timescale (2020s, 2050s, 2080s) will affect design standards of waste water networks due to the presumed increase in rainfall intensity and frequency in the Northwest of England area (selected site). Design storms have been analysed for future rainfall obtained from the UK Climate Projection version 2009 (UKCP09) weather generator, which was applied to the existing urban drainage system to check the level of service in winter and summer seasons. Two emission scenarios (SRES) have been adopted to simulate the greenhouse gas concentration; high scenario (A1FI) and low scenario (B1). Results indicate that the impact of increase in the deign storm of the system in winter lead to a potential of increase flood volume from manholes and intern basements at risk of flooding with the worst condition associated with 24 hours storm in 2080s. Moreover, when this design storm depth increased by only 15%, the corresponding flood volume increase by 40%, this indicates that the relation between the cause of flooding and its consequences is non-linear. Summer season has an opposite picture and flood volume is projected to decrease with the increase in the storm duration causing low risk. Considering climate change in this study caused most of urban drainage models runs to be very slow with some interruption in the simulation due to the inflation in some parameters, so cautious should be taken

    Peranan Aktiviti-Aktiviti Kolej Dalam Pembangunan Kepimpinan: Sebuah Kajian Explorasi Pengalaman Pelajar di Kolej Kediaman UNIMAS

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    Pembangunan kepimpinan dalam kalangan pelajar merupakan salah satu aspek penting dalam kelangsungan tonggak pimpinan negara bangsa. Hal ini seiring dengan Pelan Strategik Pengajian Tinggi Negara (PSPTN) yang dirangka dengan visi nasional untuk mentransformasikan pengajian tinggi dalam memacu kecemerlangan dan kelestarian pembangunan modal insan minda kelas pertama khususnya dan pembangunan kepimpinan amnya. Oleh hal yang demikian, kolej-kolej kediaman universiti merupakan salah satu platform dalam mencorak dan membentuk pembangunan kepimpinan serta sahsiah pelajar yang dapat memenuhi keperluan pembangunan modal insan minda kelas pertama. Hal ini dapat dilihat menerusi penglibatan aktif pelajar-pelajar dalam aktiviti-aktiviti sama ada bersifat kolegiat atau yang berimpak tinggi seiring dengan gagasan PSPTN yang bermatlamat untuk membangunkan modal insan yang mempunyai keupayaan pengetahuan, kemahiran dan ciri-ciri peribadi yang unggul. Oleh itu, kajian ini memanfaatkan kaedah kualitatif dengan pendekatan fenomenologi bagi mengkaji peranan aktiviti-aktiviti kolej dalam pembangunan kepimpinan berdasarkan pengalaman pelajar-pelajar. Temu bual dijalankan secara mendalam (in-depth interview) melibatkan empat orang pelajar yang dipilih melalui purposive sampling dan data dianalisis menggunakan thematic analysis. Kaedah kajian ini dilihat berupaya menghasilkan data yang kaya dalam memperjelaskan serta memperhalusi pengalaman pelajar-pelajar dalam pembangunan kepimpinan di kolej kediaman. Kertas kerja ini turut membincangkan implikasi kajian terhadap pelajar-pelajar dan kolej kediaman secara spesifik dan universiti secara umum di samping mengemukakan cadangan-cadangan berkaitan peranan aktiviti-aktiviti kolej dalam pembangunan kepimpinan

    Penggunaan Bahasa Rojak: Isu dan Cabaran dalam Memantapkan Kemahiran Komunikasi Pelajar di Kolej Kediaman UNIMAS

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    Dalam arus kemodenan yang pesat dengan kemajuan infrastruktur dan teknologi maklumat yang tiada sempadan wujud fenomena berbahasa yang pelbagai. Generasi muda khususnya pelajar terdedah dengan variasi berbahasa terkini daripada medium yang rencam. Institusi Pengajian Tinggi (IPT) berperanan penting dalam melahirkan graduan yang memenuhi kehendak pasaran dan berkeupayaan tinggi dalam bersaing pada peringkat lokal dan global. Kemahiran Insaniah yang disarankan oleh Kementerian Pengajian Tinggi Malaysia (KPTM) menerusi Modul Pembangunan Kemahiran Insaniah dilihat sangat membantu mengembangkan potensi dan mengasah kemahiran pelajar di universiti khususnya. Kertas kerja ini bertujuan memerihalkan isu dan cabaran dalam pemantapan kemahiran komunikasi dalam kalangan pelajar khususnya di kolej kediaman UNIMAS dengan memperlihatkan fenomena bahasa rojak yang menjadi salah satu trend berbahasa remaja. Oleh itu, kajian yang berbentuk deskriptif ini memanfaatkan kaedah temu bual yang melibatkan enam orang pelajar. Penelitian kajian dilihat berupaya menghasilkan data yang pelbagai dengan berfokuskan kepada percampuran kod yang menjadi kelaziman pertuturan dalam kalangan remaja khususnya pelajar universiti. Kertas kerja ini turut membincangkan implikasi kajian terhadap kemahiran komunikasi dalam kalangan pelajar yang akan menempuh dunia pekerjaan serta bersaing dalam memenuhi kehendak pasaran nasional dan global

    A Comparative Study of Some Cellular Manufacturing Techniques

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    Cellular manufacturing (CM) is a concept that involves processing of similar parts on dedicated cluster (or cells) of dissimilar machines or manufacturing processes. This paper concentrated on seven cell formation techniques used in Cellular Manufacturing (CM). The techniques were used to develop cells for matrices from various sizes of parts and machines. By randomly rearranging the sequence of the machines in the reference matrices (cited from published journals), 12 new matrices were developed. This paper also concentrated on performing the treatments for bottleneck, exceptional elements or voids using part subcontracting or machine duplication for the developed cells. The performance of each technique was measured using Grouping Measures (GM), where high percentage of GM indicates that the technique has high machine utilization (MU) and low percentage of exceptional elements (EE). Overall, Bond Energy Algorithm (BEA) was found to be the best cell formation technique

    Platelet-derived growth factor-stimulated versican synthesis but not glycosaminoglycan elongation in vascular smooth muscle is mediated via Akt phosphorylation

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    Proteoglycans are associated with the initiation of atherosclerosis due to their binding of apolipoproteins on lipid particles leading to retention in the vessel wall. The signaling pathways through which growth factors regulate the synthesis and structure of proteoglycans are potential therapeutic targets. Platelet-derived growth factor (PDGF) is present in atherosclerotic plaques and activates phosphorylation of the serine/threonine kinase Akt. We have investigated the role of Akt in the signaling pathways for proteoglycan core protein expression and elongation of glycosaminoglycan chains on proteoglycans secreted by human vascular smooth muscle cells. The pharmacological inhibitor of Akt phosphorylation, SN30978, blocked PDGF stimulated phosphorylation of Akt. SN30978 caused concentration dependent inhibition of PDGF stimulated radiosulfate incorporation into secreted proteoglycans and the response was blocked by the PDGF receptor antagonists Ki11502 and imatinib. Analysis of the size of the biglycan molecules by SDS-PAGE showed that PDGF increased the apparent size of biglycan but this effect on glycosaminoglycan chain elongation was blocked by Ki11502 but not by SN30978. PDGF also stimulated total protein core protein synthesis assessed as 35S-methionine/cysteine incorporation and specifically the expression of versican mRNA. Both of these responses were blocked by SN30978. This data shows that PDGF-stimulated proteoglycan core protein synthesis but not glycosaminoglycan chain elongation is mediated via Akt phosphorylation. These data identify potential pathways for the development of agents which can pharmacologically regulate individual components of the synthesis of proteoglycans
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