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Quality Degradation (quality + degradation)
Selected AbstractsIncremental Updates for Rapid Glossy Global IlluminationCOMPUTER GRAPHICS FORUM, Issue 3 2001Xavier Granier We present an integrated global illumination algorithm including non-diffuse light transport which can handle complex scenes and enables rapid incremental updates. We build on a unified algorithm which uses hierarchical radiosity with clustering and particle tracing for diffuse and non-diffuse transport respectively. We present a new algorithm which chooses between reconstructing specular effects such as caustics on the diffuse radiosity mesh, or special purpose caustic textures, when high frequencies are present. Algorithms are presented to choose the resolution of these textures and to reconstruct the high-frequency non-diffuse lighting effects. We use a dynamic spatial data structure to restrict the number of particles re-emitted during the local modifications of the scene. By combining this incremental particle trace with a line-space hierarchy for incremental update of diffuse illumination, we can locally modify complex scenes rapidly. We also develop an algorithm which, by permitting slight quality degradation during motion, achieves quasi-interactive updates. We present an implementation of our new method and its application to indoors and outdoors scenes. [source] Distance separated simultaneous sweeping, for fast, clean, vibroseis acquisitionGEOPHYSICAL PROSPECTING, Issue 1 2010Jack Bouska ABSTRACT Distance separated simultaneous sweeping DS3 is a new vibroseis technique that produces independent records, uncontaminated by simultaneous source interference, for a range of offsets and depths that span all target zones of interest. Use of DS3 on a recent seismic survey in Oman, resulted in a peak acquisition rate of 1024 records per hour. This survey employed 15 vibrators, with a distance separation of 12 km between simultaneous active sources, recorded by 8000 active channels across 22 live lines in an 18.5 km × 11 km receiver patch. Broad distribution of simultaneous sources, across an adequately sized recording patch, effectively partitions the sensors so that each trace records only one of the simultaneous sources. With proper source separation, on a scale similar to twice the maximum usable source receiver offset, wavefield overlap occurs below the zone of interest. This yields records that are indistinguishable from non-simultaneous source data, within temporal and spatial limits. This DS3 technique may be implemented using a wide variety of acquisition geometries, optimally with spatially large recording patches that enable appropriate source separation distances. DS3 improves acquisition efficiency without data quality degradation, eliminating the requirement for special data processing or noise attenuation. [source] Smoothing and transporting video in QoS IP networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2006Khaled Shuaib Abstract Real-time traffic such as voice and video, when transported over the Internet, demand stringent quality of service (QoS) requirements. The current Internet as of today is still used as a best effort environment with no quality guarantees. An IP-based Internet that supports different QoS requirements for different applications has been evolving for the past few years. Video streams are bursty in nature due to the instant variability of the video content being encoded. To help mitigate the transport of bursty video streams with minimal loss of information, rate-adaptive shapers (RASs) are usually being used to reduce the burstiness and therefore help preserve the desired quality. When transporting video over a QoS IP network, each stream is classified under a specific traffic profile to which it must conform, to avoid packet loss and picture quality degradation. In this paper we study, evaluate and propose RASs for the transport of video over a QoS IP network. We utilize the encoding video parameters for choosing the appropriate configuration needed to support the real-time transport of Variable Bit Rate (VBR) encoded video streams. The performance evaluation of the different RASs is based on the transport of MPEG-4 video streams encoded as VBR. The performance is studied based on looking at the effect of various parameters associated with the RASs on the effectiveness of smoothing out the burstiness of video and minimizing the probability of packet loss. Copyright © 2005 John Wiley & Sons, Ltd. [source] Degradative enzymatic activities in fresh-cut blood-orange slices during chilled-storageINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Anna Eghle Catalano Summary Blood-orange fruits are suitable to fresh-cut fruit production because of their chemical compositions. Nevertheless, the main limitation of using freshly cut oranges is their susceptibility to juiciness loss and ascorbic acid degradation because of enzymatic alterations. The aim of this work is: to identify some of the enzymes causing the qualitative decay in blood-orange slices during 15 days of chilled storage (at 4 ± 0.5 °C and 85% RH); to investigate the susceptibility to the previous alterations of five blood-orange clones (Moro nucellare, Sanguinello nucellare, Tarocco arcimusa, Tarocco gallo and Tarocco meli) to select the most suitable one for fresh-cut production. The enzymes studied were: pectinmethylesterase (PME) as index of juiciness loss, ascorbate oxidase (AAO) as index of ascorbic acid's degradation and polyphenol oxidase (PPO) as browning index. As far as we know, the changes of AAO activity during chilled storage of blood-orange fresh-cut slices has not previously reported and studied. Different clones showed different enzymatic activities and quality changes during chilled-storage. In particular a low juiciness loss in orange slices was correlated with a lower PME activity, as described in T. meli clone, while a high degradation of ascorbic acid was correlated with an higher AAO activity, as described in T. gallo clone; PPO activity seemed to have no significant action in quality degradation. Tarocco meli was the most suitable clone to the fresh-cut blood-orange production because it has the lowest enzymatic activity (PME, PPO and AAO) and the highest sensorial quality. [source] A novel methodology for robust VBR video transmission in an ATM systemINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2002A. Alheraish A dynamic FEC (DFEC) scheme for VBR video in ATM networks is proposed. The scheme combines the design of source encoder, error control, and the network. In the design, we will develop a methodology to vary FEC redundancy dynamically. The methodology considers the fluctuations in video source and network utilisation to adjust the FEC redundancy levels. We demonstrate the effectiveness of the proposed scheme by examining its performance with three existing schemes in terms of loss rates, throughput, and quality degradation. Copyright © 2002 John Wiley & Sons, Ltd. [source] The relationships between stocking density and welfare in farmed rainbow troutJOURNAL OF FISH BIOLOGY, Issue 3 2002T. Ellis There is increasing public, governmental and commercial interest in the welfare of intensively farmed fish and stocking density has been highlighted as an area of particular concern. Here we draw scientific attention and debate to this emerging research field by reviewing the evidence for effects of density on rainbow trout. Although no explicit reference to ,welfare' has been made, there are 43 studies which have examined the effects of density on production and physiological parameters of rainbow trout. Increasing stocking density does not appear to cause prolonged crowding stress in rainbow trout. However, commonly reported effects of increasing density are reductions in food conversion efficiency, nutritional condition and growth, and an increase in fin erosion. Such changes are indicative of a reduced welfare status,although the magnitude of the effects has tended to be dependent upon study-specific conditions. Systematic observations on large scale commercial farms are therefore required, rather than extrapolation of these mainly small-scale experimental findings. There is dispute as to the cause of the observed effects of increasing density, with water quality deterioration and/or an increase in aggressive behaviour being variously proposed. Both causes can theoretically generate the observed effects of increasing density, and the relative contribution of the two causes may depend upon the specific conditions. However, documentation of the relationship between density and the effects of aggressive behaviour at relevant commercial densities is lacking. Consequently only inferential evidence exists that aggressive behaviour generates the observed effects of increasing density, whereas there is direct experimental evidence that water quality degradation is responsible. Nevertheless, there are contradictory recommendations in the literature for key water quality parameters to ensure adequate welfare status. The potential for welfare to be detrimentally affected by non-aggressive behavioural interactions (abrasion, collision, obstruction) and low densities (due to excessive aggressive behaviour and a poor feeding response) have been largely overlooked. Legislation directly limiting stocking density is likely to be unworkable, and a more practical option might be to prescribe acceptable levels of water quality, health, nutritional condition and behavioural indicators. [source] Influence of Storage Atmosphere and Temperature on Quality Evolution of Cut Belgian EndivesJOURNAL OF FOOD SCIENCE, Issue 8 2001M.D. Van de Velde ABSTRACT: An optimal combination of O2, CO2, and N2 for storage of cut Belgian Endive was defined, investigating visual quality aspects. In the experimental design, principles of mixture theory were used. The acceptability of cut endives stored under different gas combinations, selected in the range where both CO2 and O2 were varied between 2% and 18%, was evaluated by a consumer panel at different time intervals during storage. The response was modeled with a second-degree polynomial, the response surface pointed in the direction of a gas mixture 10% CO2, 10% O2, and 80% N2 for maximum acceptability or best quality during storage. Repeated experiments, including different varieties from 2 different growers, confirmed the optimal gas concentration, (10% CO2, 10% O2, and 80% N2). In a second step, the effect of temperature on quality degradation of cut endives stored under optimal atmosphere conditions, was quantified using the Arrhenius equation. An activation energy of 16.3 kcal/mol was obtained. [source] Improved slice selection for R2* mapping during cryoablation with eddy current compensation,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2008Aiming Lu PhD Abstract Purpose To improve the slice profile and image quality of R2* mapping in the iceball during cryoablation with ultrashort echo time (UTE) imaging by compensating for eddy currents induced by the selective gradient when half-pulse radiofrequency (RF) excitation is employed to achieve UTEs. Materials and Methods A method to measure both B0 and linear eddy currents simultaneously is first presented. This is done with a least-square fitting process on calibration data collected on a phantom. Eddy currents during excitation are compensated by redesigning the RF pulse and the selective gradient accordingly, while that resultant from the readout gradient are compensated for during image reconstruction. In vivo data were obtained continuously during the cryoablation experiments to calculate the R2* values in the iceball and to correlate them with the freezing process. Results Image quality degradation due to eddy currents is significantly reduced with the proposed approaches. R2* maps of iceball throughout the cryoablation experiments were achieved with improved quality. Conclusion The proposed approaches are effective for compensating eddy currents during half-pulse RF excitation as well as readout. TEs as short as 100 ,sec were obtained, allowing R2* maps to be obtained from frozen tissues with improved quality. J. Magn. Reson. Imaging 2008;28:190,198. © 2008 Wiley-Liss, Inc. [source] Simulated rainfall evaluation of revegetation/mulch erosion control in the Lake Tahoe Basin,1: method assessmentLAND DEGRADATION AND DEVELOPMENT, Issue 6 2004M. E. Grismer Abstract Revegetation of road cuts and fills is intended to stabilize those drastically disturbed areas so that sediment is not transported to adjacent waterways. Sediment has resulted in water quality degradation, an extremely critical issue in the Lake Tahoe Basin. Many revegetation efforts in this semiarid, subalpine environment have resulted in low levels of plant cover, thus failing to meet project goals. Further, no adequate physical method of assessing project effectiveness has been developed, relative to runoff or sediment movement. This paper describes the use of a portable rainfall simulator (RS) to conduct a preliminary assessment of the effectiveness of a variety of erosion-control treatments and treatment effects on hydrologic parameters and erosion. The particular goal of this paper is to determine whether the RS method can measure revegetation treatment effects on infiltration and erosion. The RS-plot studies were used to determine slope, cover (mulch and vegetation) and surface roughness effects on infiltration, runoff and erosion rates at several roadcuts across the basin. A rainfall rate of ,60,mm,h,1, approximating the 100-yr, 15-min design storm, was applied over replicated 0·64,m2 plots in each treatment type and over bare-soil plots for comparison. Simulated rainfall had a mean drop size of ,2·1,mm and approximately 70% of ,natural' kinetic energy. Measured parameters included time to runoff, infiltration, runoff/infiltration rate, sediment discharge rate and average sediment concentration as well as analysis of total Kjeldahl nitrogen (TKN) and dissolved phosphorus (TDP) from filtered (0·45,,m) runoff samples. Runoff rates, sediment concentrations and yields were greater from volcanic soils as compared to that from granitic soils for nearly all cover conditions. For example, bare soil sediment yields from volcanic soils ranged from 2,12 as compared to 0·3,3,g,m,2,mm,1 for granitic soils. Pine-needle mulch cover treatments substantially reduced sediment yields from all plots. Plot microtopography or roughness and cross-slope had no effect on sediment concentrations in runoff or sediment yield. RS measurements showed discernible differences in runoff, infiltration, and sediment yields between treatments. Runoff nutrient concentrations were not distinguishable from that in the rainwater used. Copyright © 2004 John Wiley & Sons, Ltd. [source] Differences between chloro-carbon and hydro-carbon precursors in low-temperature epitaxial growth of 4H-SiCPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010Siva Kotamraju Abstract The advantages of using the chlorinated carbon precursor chloromethane instead of the hydrocarbon precursor propane in low-temperature (1300 °C) epitaxial growth of 4H-SiC were investigated. Chloromethane was found to provide a much wider process window for variation of the C/Si ratio between the lower boundary corresponding to the formation of condensed silicon face and the upper boundary corresponding to polytype inclusions and polycrystalline degradation, which is critical for achieving high growth rates without epilayer quality degradation. Use of a high Cl/Si ratio provided by HCl addition in the propane-based epitaxial growth did not eliminate the critical differences between chloro-carbon and hydro-carbon precursors. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Improving the Quality of Information Flows in the Backend of a Product Development Process: a Case StudyQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 2 2005Jaring Boersma Abstract Considerable research has gone into designing effective product development processes. This, coupled with the increasing need for products that are able to deliver reliable, complex functionality with a high degree of innovation, presents a major challenge to modern day industries in the business of developing products. In order to incorporate relevant field experience in the design and manufacturing of new products, increasingly detailed information needs to be retrieved from the market in a very short amount of time. In one particular consumer electronics industry, business process models describing the information flow in the backend of the product development process indicated massive data loss and also serious data quality degradation. This paper attempts to show how such losses can be mitigated and also proposes a business model that can adequately capture information of a higher quality and in a more structured manner. The end result will be a product development process that provides better feedback on current product performance and is more responsive to future market needs. Copyright © 2005 John Wiley & Sons, Ltd. [source] Quality of Information Flow in the Backend of a Product Development Process: a Case StudyQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 4 2004Jaring Boersma Abstract The increasing need for products that are able to reliably deliver complex functionality with a high degree of innovation presents a major challenge to the modern day product creation processes. In order to be able to use information on the field behaviour of previous products in the design of new products, increasingly detailed information needs to be retrieved from the market in an increasingly shorter time. The purpose of this study is to analyse, in a typical case in the consumer electronics industry, whether the underlying business process is able to generate this information with adequate quality sufficiently quickly. Information models of the company's service centre and call centre were developed using the concepts of maturity index on reliability. The results showed that the structure of the information handling process resulted in a massive data loss (up to 60% of the data gathered by the service centres) and also in serious data quality degradation. Would this information have not been lost, it could have been used by development teams for preventive and corrective actions. Copyright © 2004 John Wiley & Sons, Ltd. [source] From Time Temperature Integrator Kinetics to Time Temperature Integrator Tolerance Levels: Heat-Treated MilkBIOTECHNOLOGY PROGRESS, Issue 1 2004Wendie L. Claeys Six milk compounds were studied as potential intrinsic time temperature integrators (TTIs) for the assessment of heat-treated milk. These include the enzymes alkaline phosphatase and lactoperoxidase, the whey protein ,-lactoglobulin and the chemical compounds hydroxymethylfurfural, lactulose and furosine. In previous research the inactivation/denaturation/formation kinetics of these compounds were analyzed under isothermal and nonisothermal conditions and evaluated for variability of the milk composition. The present paper focuses on the implementation of the TTIs. TTIs are validated with respect to microbiological indices and quality attributes, and a quantitative relationship between the denaturation, inactivation or formation of the TTIs and technological processes is established by construction of general time temperature tolerance (TTT) diagrams. In these diagrams temperature time combinations are presented, which lead to the same formation, inactivation or denaturation of TTIs, or result in the same level of microbiological destruction or quality degradation of the product. TTT-diagrams are very informative since they allow visualization of the impact of a thermal process on milk and evaluation of criteria for evaluating milk authenticity (conformity of the product with the terminology applied). Moreover, the optimum combination of temperature and time of heating may be readily deduced from these diagrams. [source] KINETICS OF HYDROXYMETHYLFURFURAL ACCUMULATION AND COLOR CHANGE IN HONEY DURING STORAGE IN RELATION TO MOISTURE CONTENTJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2009L. BULUT ABSTRACT Quality reduction in honey during storage is indicated by hydroxymethylfurfural (HMF) accumulation and darkening of color. The effects of moisture content and temperature on HMF accumulation and color change in honey during storage were investigated. HMF accumulation and color change followed first- and zero-order reaction kinetics, respectively. The moisture content affected the rate of the two degradation reactions depending on the storage temperature. Reduction in moisture content caused an increase in rate constant for HMF accumulation at 20 and 30C, but there was no significant effect of moisture content at 40C. Rate constants for change in lightness and total color change values increased with increasing moisture content at 20 and 30C. The highest rate constant for change in color values was obtained at a moisture content of 18% at 40C. PRACTICAL APPLICATIONS Hydroxymethylfurfural accumulation and color change are two major quality degradations in honey during storage. This study shows that the rates of these two degradations are dependent on moisture content of honey. In addition, effect of moisture content on the rates of reactions was dependent on temperature of storage. Therefore, producers need to consider the effects of both moisture content and storage temperature in reducing quality loss in honey during storage. [source] | |||||||||||||||||||