SDN-based architecture for providing quality of service to high-performance distributed applications

The specification of quality of service (QoS) requirements in most of the existing networks is still challenging. In part, traditional network environments are limited by their high administrative cost, although software-defined networks (SDNs), a newer network paradigm, simplify the management of the whole network infrastructure. In fact, SDN provides a simple way to effectively develop QoS provisioning mechanisms. In this sense, we explore the SDN model and its flexibility to develop a QoS provisioning architecture. Through the use of our new architecture, network operators are able to specify QoS levels in a simple way. Each individual data flow can be addressed, and the architecture we propose also negotiates the QoS requirements between the network controller and applications. On the other hand, the network controller continuously monitors the network environment. Then, it allocates network elements resources and prioritizes traffic, adjusting the network performance. We evaluate the feasibility of our QoS provisioning mechanism by presenting three experimental setups under realistic scenarios. For example, for a given scenario where we evaluate file transfers, our results indicate that the additional SDN modules present negligible overhead. Moreover, for a given setup, we observe a reduction of up to 82% in the file transfer times.     

Image modeling based on a 2-D stochastic subspace system identification algorithm

Fitting a causal dynamic model to an image is a fundamental problem in image processing, pattern recognition, and computer vision. In image restoration, for instance, the goal is to recover an estimate of the true image, preferably in the form of a parametric model, given an image that has been degraded by a combination of blur and additive white Gaussian noise. In texture analysis, on the other hand, a model of a particular texture image can serve as a tool for simulating texture patterns. Finally, in image enhancement one computes a model of the true image and the residuals between the image and the modeled image can be interpreted as the result of applying a de-noising filter. There are numerous other applications within the field of image processing that require a causal dynamic model. Such is the case in scene analysis, machined parts inspection, and biometric analysis, to name only a few. There are many types of causal dynamic models that have been proposed in the literature, among which the autoregressive moving average and state-space models (i.e., Kalman filter) are the most commonly used. In this paper we introduce a 2-D stochastic state-space system identification algorithm for fitting a quarter plane causal dynamic Roesser model to an image. The algorithm constructs a causal, recursive, and separable-in-denominator 2-D Kalman filter model. The algorithm is tested with three real images and the quality of the estimated images are assessed.     

Impact of growth rate on the quality of ZNS-MQW InGaAsP/InP laser structures grown by LP-MOVPE

We investigated the influence of the growth rate on the quality of zero-net-strained InGaAsP/InGaAsP/InP multiquantum well structures for 1.55 μm emission grown by low pressure metalorganic vapor phase epitaxy. The samples consisted of fixed compressive strained wells (ɛ=+1%) and tensile strained barriers (ɛ=−0.5%) grown with different quaternary bandgap wavelengths (λ_B=1.1–1.4 μm). Using higher growth rates, we obtained for the first time high quality zero net strained multi quantum well structures, regardless having constant group V composition in the well and barriers. The samples were analyzed by x-ray diffraction, photoluminescence and atomic force microscopy techniques. The amplitude of surface modulation roughness along [011] direction decreased from 20 nm to 0.53 nm with increasing growth rate and/or quaternary compositions grown outside the miscibility gap. A new deep PL broad emission band strongly correlated with the onset of wavy layer growth is also reported. Broad area and ridge waveguide lasers with 10 wells exhibited low losses (34 cm⁻¹) and low threshold current densities at infinite cavity length (1020 A·cm⁻² and 1190 A·cm⁻², respectively).     

Probabilistic linear models for multiresolution estimation in gray-level images

A multiresolution analysis of digital gray-level images is presented. A gray-level multi-scale framework is determined from two main assumptions: the gray scale is binary at the finest spatial resolution, and the gray levels of composed regions are obtained additively. In order to interrelate the gray-level histograms of the same image at different resolutions, probabilistic linear models are developed, which are then applied for estimation. Linear-optimization theory is used as a way of constructing such models. A general procedure for image processing is sketched, based on gray-level estimation. A versatile algorithm for nonlinear filtering is derived. Some examples of prospective applications are given.This work was partially supported by grant TIC91-646 from the DGYCIT of the Spanish Government.     

Rapid Generation of Biologically Relevant Hydrogels Containing Long‐Range Chemical Gradients

Many biological processes are regulated by gradients of bioactive chemicals. Thus, the generation of materials with embedded chemical gradients may be beneficial for understanding biological phenomena and generating tissue‐mimetic constructs. Here a simple and versatile method to rapidly generate materials containing centimeter‐long gradients of chemical properties in a microfluidic channel is described. The formation of a chemical gradient is initiated by a passive‐pump‐induced forward flow and further developed during an evaporation‐induced backward flow. The gradient is spatially controlled by the backward flow time and the hydrogel material containing the gradient is synthesized via photopolymerization. Gradients of a cell‐adhesion ligand, Arg‐Gly‐Asp‐Ser (RGDS), are incorporated in poly(ethylene glycol)‐diacrylate (PEG‐DA) hydrogels to test the response of endothelial cells. The cells attach and spread along the hydrogel material in a manner consistent with the RGDS‐gradient profile. A hydrogel containing a PEG‐DA concentration gradient and constant RGDS concentration is also shown. The morphology of cells cultured on such hydrogel changes from round in the lower PEG‐DA concentration regions to well‐spread in the higher PEG‐DA concentration regions. This approach is expected to be a valuable tool to investigate the cell–material interactions in a simple and high‐throughput manner and to design graded biomimetic materials for tissue engineering applications.     

UNICORE 6 — Recent and Future Advancements

UNICORE is a European Grid Technology with more than 10 years of history. Originating from the Supercomputing domain, the latest version UNICORE 6 has turned into a general-purpose Grid technology that follows established standards and offers a rich set of features to its users. The paper starts with an architectural insight into UNICORE 6, highlighting the workflow features, standards and the different clients. Next, the current state of advancement is presented by describing recent developments. The paper closes with an outlook on future planned developments.     

Propagation Path Loss and Materials Insertion Loss in Indoor Environment at WiMAX Band of 3.3 to 3.6?GHz

The purpose of this study is to characterize the indoor channel for IEEE 802.16 (WiMAX) at 3.3?C3.6?GHz frequency. This work presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include closed corridor, wide corridor and semi open corridor. Path loss equations are determined using log-distance path loss model and a Rayleigh multipath induced fading, Normal multipath induced fading or a combination of both. A numerical analysis of measurements in each scenario was conducted and the study determined equations that describe path loss for each scenario. Propagation loss is given for 300?MHz bandwidth. This work also represents the insertion loss of different materials and the obstruction loss due the existence of human beings between the transmitting antenna and the receiving one.     

IEEE-Compliant IDCT on FPGA-Augmented TriMedia

This paper presents a TriMedia processor extended with an IDCT reconfigurable design, and assesses the performance gain such an extension has when performing MPEG-2 decoding. We first propose the skeleton of an extension of the TriMedia architecture, which consists of a Field-Programmable Gate Array (FPGA)-based Reconfigurable Functional Unit (RFU), a Configuration Unit managing the reconfiguration of the RFU, and their associated instructions. Then, we address the computation of the 8 × 8 (2-D) IDCT on such extended TriMedia and propose a scheme to implement the 1-D IDCT operation on the RFU. When mapped on an ACEX EP1K100 FPGA from Altera, the proposed 1-D IDCT exhibits a latency of 16 and a recovery of 2 TriMedia@200 MHz cycles, and occupies 45% of the logic cells of the device. By configuring the 1-D IDCT on the RFU at application launch-time, the IEEE-compliant 2-D IDCT can be computed with the throughput of 1/32 IDCT/cycle. This figure translates to an improvement over the standard TriMedia of more than 40% in terms of computing time when 2-D IDCT is carried out in the framework of MPEG-2 decoding. Finally, the proposed reconfigurable IDCT is compared to a number of existing designs.Mihai Sima was born in Bucharest, Romania. He received the MS degree in Electrical Engineering from Politehnica University of Bucharest, and the Ph.D. degree in Electrical Engineering from Delft University of Technology, The Netherlands. He had been with the Microelectronics Company in Bucharest for 3 years, where he was involved in instrumentation electronics for integrated circuit testing. Subsequently, he joined the Telecommunications Department of Politehnica University of Bucharest, where he had been involved in digital signal processing and speech recognition for 6 years. More recently, he had been with the Faculty of Electrical Engineering, Mathematics, and Computer Science, Delft University of Technology, where he worked on reconfigurable architectures for mediaprocessing domain. He is currently an assistant professor with the Department of Electrical and Computer Engineering, University of Victoria, B.C., Canada. His research interests include computer architecture, reconfigurable computing, embedded systems, digital signal processing, and speech recognition.Sorin D. Coofan was born in Mizil, Romania. He received the MS degree in Computer Science from the Politehnica University of Bucharest, Romania, and the Ph.D. degree in Electrical Engineering from Delft University of Technology, The Netherlands. He had worked with the Research & Development Institute for Electronic Components (ICCE) in Bucharest for a decade, being involved in structured design of digital systems, design rule checking of ICs layout, logic and mixed-mode simulation of electronic circuits, testability analysis, and image processing. He is currently an associate professor with the Faculty of Electrical Engineering, Mathematics, and Computer Science, Delft University of Technology, The Netherlands. His research interests include computer arithmetic, parallel architectures, embedded systems, reconfigurable computing, nano-electronics, neural networks, computational geometry, and computer aided design.Jos T.J. van Eijndhoven was born in Roosendaal, The Netherlands. He studied Electrical Engineering at the Eindhoven University of Technology, The Netherlands, obtaining the M.Sc. and Ph.D. degrees in 1981 and 1984, respectively, for a work on piecewise linear circuit simulation. Then, he became a senior research member in the design automation group of the Eindhoven University of Technology. In 1986 he spent a sabbatical period at the IBM Thomas J. Watson Research Laboratory, Yorktown Heights, New York, for research on high level synthesis. In 1998 he joined Philips Research Laboratories in Eindhoven, The Netherlands, to work on the architectural design of programmable multimedia hardware and the associated mapping of media processing applications.Stamatis Vassiliadis was born in Manolates, Samos, Greece. He is a professor with the Faculty of Electrical Engineering, Mathematics, and Computer Science, Delft University of Technology, The Netherlands. He has also served in the faculties of Cornell University, Ithaca, NY, and the State University of New York (S.U.N.Y.), Binghamton, NY.He hadworked for a decade with IBM in the AdvancedWorkstations and Systems laboratory in Austin TX, the Mid-Hudson Valley Laboratory in Poughkeepsie, NY, and the Glendale Laboratory in Endicott, NY. In IBM he was involved in a number of projects regarding computer design, organizations, and architectures and the leadership to advanced research projects. A number of his design and implementation proposals have been implemented in commerciallyavailable systems and processors including the IBM 9370 model 60 computer system, the IBM POWER II, the IBM AS/400 Models 400, 500, and 510, Server Models 40S and 50S, the IBM AS/400 Advanced 36, and the IBM S/390 G4 and G5 computer systems. For his work, he received numerous awards including 23 levels of Publication Achievement Awards, 15 levels of Invention Achievement Awards and an Outstanding Innovation Award for Engineering/Scientific Hardware Design in 1989. In 1990 he has been awarded the highest number of USA patents in IBM, six of his 70 USA patents being rated with the highest patent ranking in IBM.Kees A. Vissers graduated the Delft University of Technology, receiving his M.Sc. in 1980. He started directly with Philips Research Laboratories in Eindhoven where he was involved in highlevel simulation and high-level synthesis. He had been heading the research on hardware/software co-design and system level design for many years, and had a significant contribution to the TriMedia VLIW processor. From 1987 till 1988 he was a visiting researcher at Carnegie Mellon University, Pittsburgh, Pennsylvania, with the group of Don Thomas. He is currently a Research Fellow with University of California at Berkeley, Department of Electrical Engineering and Computer Sciences. His research interests include video processing, embedded media processing systems, and reconfigurable computing.     

Scanning electron microscopic observation on the equatorial region of the rat intrafusal muscle fibres, especially on the subsarcolemmal sarcoplasmic reticulum

We examined intracellular structures in the equatorial region of the muscle spindles of rat soleus muscles by scanning electron microscopy, paying particular attention to the ultrastructure of the sarcoplasmic reticulum (SR) beneath the sarcolemma. The subsarcolemmal SR was more developed in nuclear chain fibres than in nuclear bag fibres as was reported in the sleeve and extracapsular regions. In addition, the subsarcolemmal SR of the chain fibre formed a fenestrated sheet, whereas that of the bag fibre organized a layer of fenestrated bands beneath the sarcolemma where the sensory nerve endings are associated. No T-tubules were discerned in the subsarcolemmal SR of both fibres, which may be concerned with the little contraction of the equatorial region.