7,670 research outputs found
ECEM: an event correlation based event manager for an I/O-intensive application
No full textIn Internet servers that run on general purpose operating systems, network subsystems and disk subsystems cooperate with each other for user requests. Many studies have focused on optimizing the data movement across the subsystems to reduce data copying overhead among kernel buffers, a network send buffer and a disk buffer. When data are moved across the subsystems, events such as read requests and write requests for data movement are also delivered across the subsystems by the servers and the operating system. However. there have been fewer Studies on the optimization of event delivery across the subsystems. In conventional operating systems, an event from a disk subsystem is delivered to a network subsystem regardless of the status of the network subsystem. If the network Subsystem is not ready for data sending, the execution of the server will be blocked, which causes scheduling and context switching overheads. This non-contiguous execution will incur deficiencies such as avoidable process blocking, context switching, cache pollution and long response time. To alleviate the deficiencies, we have developed inter-subsystem event delivery mechanisms that define event dependencies among the subsystems involved. We define an event correlation based on the happened-before relation. We propose deferred event delivery (DED) and disk-to-network splicing (DNS) to suppress scheduling and context switching during I/O request processing. We performed experiments on Linux 2.4 and the experimental results show that the number of context switching is reduced by up to 20% and server data transmit rate is improved by 4.0-8.1%. (C) 2003 Elsevier Inc. All rights reserved
Four and a half LIM protein 1C (FHL1C)
No full textFour-and-a-half LIM domain protein 1 isoform A (FHL1A) is predominantly expressed in skeletal and cardiac muscle. Mutations in the FHL1 gene are causative for several types of hereditary myopathies including X-linked myopathy with postural muscle atrophy (XMPMA). We here studied myoblasts from XMPMA patients. We found that functional FHL1A protein is completely absent in patient myoblasts. In parallel, expression of FHL1C is either unaffected or increased. Furthermore, a decreased proliferation rate of XMPMA myoblasts compared to controls was observed but an increased number of XMPMA myoblasts was found in the G(0)/G(1) phase. Furthermore, low expression of K(v1.5), a voltage-gated potassium channel known to alter myoblast proliferation during the G(1) phase and to control repolarization of action potential, was detected. In order to substantiate a possible relation between K(v1.5) and FHL1C, a pull-down assay was performed. A physical and direct interaction of both proteins was observed in vitro. In addition, confocal microscopy revealed substantial colocalization of FHL1C and K(v1.5) within atrial cells, supporting a possible interaction between both proteins in vivo. Two-electrode voltage clamp experiments demonstrated that coexpression of K(v1.5) with FHL1C in Xenopus laevis oocytes markedly reduced K(+) currents when compared to oocytes expressing K(v1.5) only. We here present the first evidence on a biological relevance of FHL1C
Autonomous management of clustered server systems using JINI
No full textA framework for the autonomous management of clustered server systems called LAMA(1) (Large-scale system's Autonomous Management Agent) is proposed in this paper. LAMA is based on agents, which are distributed over the nodes and built on JINI infrastructure. There are two classes of agents: a grand LAMA and ordinary LAMAs. An ordinary LAMA abstracts an individual node and performs node-wide configuration. The grand LAMA is responsible for monitoring and controlling all the ordinary ones. Using the discovery,join, lookup, and distributed security operations of JINI, anode can join the clustered system without secure administration. Also, a node's failure can be detected automatically using the lease interface of the JINI. Resource reallocation is performed dynamically by a reallocation engine in the grand agent. The reallocation engine gathers the status of remote nodes, predicts resource demands, and executes reallocation by accessing the ordinary agents. The proposed framework is verified on our own clustered internet servers, called the CORE-Web server, for an audio-streaming service. The nodes are dynamically reallocated satisfying the performance requirements
Impact energy absorption characteristics of glass fiber hybrid composites
No full textIn the present study, the impact energy absorption characteristics of glass fiber-reinforced hybrid composites were investigated by the instrumented Charpy impact test method with respect to the volume fraction of different materials embedded. Also, the interlaminar shear properties were measured by the short beam shear test to investigate the correlation between the interlaminar shear properties and the impact energy absorption characteristics. To predict the impact absorption characteristics of glass fiber hybrid composites, the progressive impact fracture model was proposed. (C) 1999 Elsevier Science Ltd. All rights reserved
Impact energy absorption characteristics of composite structures
No full textThe tensile and compressive tests of glass-epoxy composites with 1-200 s(-1) strain rates which are typical strain rate range during automobile crash accidents were performed in order to measure the strength variation with respect to strain rate. The tests were performed using both a horizontal type pneumatic impact tester and a conventional dynamic universal test machine with strain-rate-increase mechanisms. Also, the impact energy absorption characteristics of glass fiber reinforced composites were estimated using the newly proposed progressive impact fracture model. From the experiments and predictions, it was found that the proposed method predicted relatively well the experimental results. (C) 2000 Published by Elsevier Science Ltd. All rights reserved
RDLS-SS-DWT v. 0.9
No full textThis fileset contains the implementation of RDLS-DWT and SS-DWT in JPEG 2000 (RDLS-SS-DWT v. 0.9), which was used in a research described in: R. Starosolski, “Application of reversible denoising and lifting steps to DWT in lossless JPEG 2000 for improved bitrates,” Signal Processing: Image Communication, Vol. 39, Part A, pp. 249-63, DOI: 10.1016/j.image.2015.09.013, 2015 and R. Starosolski, “Skipping selected steps of DWT computation in lossless JPEG 2000 for improved bitrates,” submitted. This software is intended for research purposes only; it is provided "as is"; author makes no warranty of any kind, either express or implied, with respect to this software. <br
-layer structure
No full textWe investigated a double silicon-carbide p-layer structure consisting of a undiluted p-type amorphous silicon-carbide (p-a-SiC:H) window layer and a hydrogen diluted p-a-SiC:H buffer layer to improve a pin-type amorphous silicon based solar cell. Solar cells using a lightly boron-doped (1000 ppm) buffer layer with a high conductivity, low absorption, well-ordered film structure, and slow deposition rate improves the open-circuit voltage (V-oc), short-circuit current density, and fill factor by reducing recombination in the buffer layer and at p/buffer and buffer/i interfaces. It is found that a natural hydrogen treatment generated throughout the buffer layer deposition onto the p-a-SiC:H window layer is an advantage of this double p-layer structure. We achieved a considerable initial conversion efficiency of 11.2% without any back reflector. (C) 2004 American Institute of Physics
ultraviolet treatment in an Ar ambient upon p-type hydrogenated amorphous silicon–carbide windows of hydrogenated amorphous silicon based solar cells
No full textWe proposed an in situ postdeposition ultraviolet treatment in an Ar ambient (UTA) to improve the p/i interface of amorphous silicon based solar cell. We have increased the conversion efficiency by similar to16% by improving the built-in potential and reducing recombination at the p/i interface. Through spectroscopic ellipsometry and Fourier-transform infrared measurements, it is concluded that the UTA process induces structural modification of the p-type hydrogenated amorphous silicon-carbide (p-a-SiC:H) window layer. An ultrathin p-a-SiC:H contamination layer formed during the UTA process acts as a buffer layer at the interface. (C) 2004 American Institute of Physics
Growth of silicon nanocrystals by low-temperature photo chemical vapor deposition
No full textSilicon nanocrystals on a thermally grown silicon oxide have been fabricated at a low temperature using the photo chemical vapor deposition (photo-CVD). Even at a low temperature of 150 degrees C, crystalline silicon nanocrystals are successively formed by this method. By changing the gas mixture of SiH4 and H-2, the size and number density of Si nanocrystals are systematically investigated in a controlled manner. The shape, size, and crystallinity of such nanocrystals examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). To apply Si nanocrystals in nonvolatile memory, the capacitance-voltage (CV) characteristics of Si nanocrystals are also discussed in this paper
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