944 resultados para Non Ideal System


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Non-technical losses (NTL) identification and prediction are important tasks for many utilities. Data from customer information system (CIS) can be used for NTL analysis. However, in order to accurately and efficiently perform NTL analysis, the original data from CIS need to be pre-processed before any detailed NTL analysis can be carried out. In this paper, we propose a feature selection based method for CIS data pre-processing in order to extract the most relevant information for further analysis such as clustering and classifications. By removing irrelevant and redundant features, feature selection is an essential step in data mining process in finding optimal subset of features to improve the quality of result by giving faster time processing, higher accuracy and simpler results with fewer features. Detailed feature selection analysis is presented in the paper. Both time-domain and load shape data are compared based on the accuracy, consistency and statistical dependencies between features.

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Aqueous semi-solid polymeric gels, such as those based on hydroxyethylcellulose (HEC) and polyacrylic acid (e.g. Carbopol®), have a long history of use in vaginal drug delivery. However, despite their ubiquity, they often provide sub-optimal clinical performance, due to poor mucosal retention and limited solubility for poorly water-soluble actives. These issues are particularly pertinent for vaginal HIV microbicides, since many lead candidates are poorly water-soluble and where a major goal is the development of a coitally independent, once daily gel product. In this study, we report the use of a non-aqueous silicone elastomer gel for vaginal delivery of the HIV-1 entry inhibitor maraviroc. In vitro rheological, syringeability and retention studies demonstrated enhanced performance for silicone gels compared with a conventional aqueous HEC gel, while testing of the gels in the slug model confirmed a lack of mucosal irritancy. Pharmacokinetic studies following single dose vaginal administration of a maraviroc silicone gel in rhesus macaques showed higher and sustained MVC levels in vaginal fluid, vaginal tissue and plasma compared with a HEC gel containing the same maraviroc loading. The results demonstrate that non-aqueous silicone gels have potential as a formulation platform for coitally independent vaginal HIV microbicides.

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Recently, there has been a considerable research activity in extending topographic maps of vectorial data to more general data structures, such as sequences or trees. However, the representational capabilities and internal representations of the models are not well understood. We rigorously analyze a generalization of the Self-Organizing Map (SOM) for processing sequential data, Recursive SOM (RecSOM [1]), as a non-autonomous dynamical system consisting off a set of fixed input maps. We show that contractive fixed input maps are likely to produce Markovian organizations of receptive fields o the RecSOM map. We derive bounds on parameter $\beta$ (weighting the importance of importing past information when processing sequences) under which contractiveness of the fixed input maps is guaranteed.

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The effects of channel inequality on nonlinear signal switching in a nonlinear optical fiber loop mirror (NOLM) were investigated. It was found that the channel-to-channel amplitude differences in optical time division multiplexing (OTDM) have strong impact on swiching behavior of individual channels in a 2R regenerator. The optical pulses in different channels face either suppression of the amplitude noise or increase in noise, depending on the inter-channel amplitude difference. It was stated that appropriate control of the channel uniformity in the OTDM transmitters is required to support stable long-haul transmission in 2R regenerated systems.

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Poly(e-caprolactone) (PCL) is biocompatible, non-immunogenic and non-toxic, and slowly degrades, allowing sufficient time for tissue regeneration. PCL has the potential for application in bone and cartilage repair as it may provide the essential structure required for bone regeneration, however, an ideal scaffold system is still undeveloped. PCL fibres were prepared using the gravity spinning technique, in which collagen was either incorporated into or coated onto the 'as-spun' fibres, in order to develop novel biodegradable polymer fibres which will effectively deliver collagen and support the attachment and proliferation of human osteoblast (HOB) cells for bone regeneration. The physical and mechanical characteristics and cell fibre interactions were analysed. The PCL fibres were found to be highly flexible and inclusion of collagen did not alter the mechanical properties of PCL fibres. Overall, HOB cells were shown to effectively adhere and proliferate on all fibre platforms tested, although proliferation rates were enhanced by surface coating PCL fibres with collagen compared to PCL fibres incorporating collagen and PCL-only fibres. These findings highlight the potential of using gravity spun PCL fibres as a delivery platform for extracellular matrix proteins, such as collagen, in order to enhance cell adherence and proliferation for tissue repair.

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The devising of a general engineering theory of multifunctional diagnostic systems for non-invasive medical spectrophotometry is an important and promising direction of modern biomedical engineering. We aim in this study to formalize in scientific engineering terms objectives for multifunctional laser non-invasive diagnostic system (MLNDS). The structure-functional model as well as a task-function of generalized MLNDS was formulated and developed. The key role of the system software for MLNDS general architecture at steps of ideological-technical designing has been proved. The basic principles of block-modules composition of MLNDS hardware are suggested as well. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

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The impact of design of sharp non-uniform fiber Bragg gratings on system performance was presented. The evolution of the Q-value of the worst channel against the propagation distance was shown. The results suggested that to apply approximated flat-dispersion gratings as inline filters in a periodic system, some post-compensation was included to account for the extra dispersion introduced by the gratings.

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Firms worldwide are taking major initiatives to reduce the carbon footprint of their supply chains in response to the growing governmental and consumer pressures. In real life, these supply chains face stochastic and non-stationary demand but most of the studies on inventory lot-sizing problem with emission concerns consider deterministic demand. In this paper, we study the inventory lot-sizing problem under non-stationary stochastic demand condition with emission and cycle service level constraints considering carbon cap-and-trade regulatory mechanism. Using a mixed integer linear programming model, this paper aims to investigate the effects of emission parameters, product- and system-related features on the supply chain performance through extensive computational experiments to cover general type business settings and not a specific scenario. Results show that cycle service level and demand coefficient of variation have significant impacts on total cost and emission irrespective of level of demand variability while the impact of product's demand pattern is significant only at lower level of demand variability. Finally, results also show that increasing value of carbon price reduces total cost, total emission and total inventory and the scope of emission reduction by increasing carbon price is greater at higher levels of cycle service level and demand coefficient of variation. The analysis of results helps supply chain managers to take right decision in different demand and service level situations.

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Detection canines represent the fastest and most versatile means of illicit material detection. This research endeavor in its most simplistic form is the improvement of detection canines through training, training aids, and calibration. This study focuses on developing a universal calibration compound for which all detection canines, regardless of detection substance, can be tested daily to ensure that they are working with acceptable parameters. Surrogate continuation aids (SCAs) were developed for peroxide based explosives along with the validation of the SCAs already developed within the International Forensic Research Institute (IFRI) prototype surrogate explosives kit. Storage parameters of the SCAs were evaluated to give recommendations to the detection canine community on the best possible training aid storage solution that minimizes the likelihood of contamination. Two commonly used and accepted detection canine imprinting methods were also evaluated for the speed in which the canine is trained and their reliability. As a result of the completion of this study, SCAs have been developed for explosive detection canine use covering: peroxide based explosives, TNT based explosives, nitroglycerin based explosives, tagged explosives, plasticized explosives, and smokeless powders. Through the use of these surrogate continuation aids a more uniform and reliable system of training can be implemented in the field than is currently used today. By examining the storage parameters of the SCAs, an ideal storage system has been developed using three levels of containment for the reduction of possible contamination. The developed calibration compound will ease the growing concerns over the legality and reliability of detection canine use by detailing the daily working parameters of the canine, allowing for Daubert rules of evidence admissibility to be applied. Through canine field testing, it has been shown that the IFRI SCAs outperform other commercially available training aids on the market. Additionally, of the imprinting methods tested, no difference was found in the speed in which the canines are trained or their reliability to detect illicit materials. Therefore, if the recommendations discovered in this study are followed, the detection canine community will greatly benefit through the use of scientifically validated training techniques and training aids.

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Wind energy installations are increasing in power systems worldwide and wind generation capacity tends to be located some distance from load centers. A conflict may arise at times of high wind generation when it becomes necessary to curtail wind energy in order to maintain conventional generators on-line for the provision of voltage control support at load centers. Using the island of Ireland as a case study and presenting commercially available reactive power support devices as possible solutions to the voltage control problems in urban areas, this paper explores the reduction in total generation costs resulting from the relaxation of the operational constraints requiring conventional generators to be kept on-line near load centers for reactive power support. The paper shows that by 2020 there will be possible savings of 87€m per annum and a reduction in wind curtailment of more than a percentage point if measures are taken to relax these constraints.

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Due to trends in aero-design, aeroelasticity becomes increasingly important in modern turbomachines. Design requirements of turbomachines lead to the development of high aspect ratio blades and blade integral disc designs (blisks), which are especially prone to complex modes of vibration. Therefore, experimental investigations yielding high quality data are required for improving the understanding of aeroelastic effects in turbomachines. One possibility to achieve high quality data is to excite and measure blade vibrations in turbomachines. The major requirement for blade excitation and blade vibration measurements is to minimize interference with the aeroelastic effects to be investigated. Thus in this paper, a non-contact-and thus low interference-experimental set-up for exciting and measuring blade vibrations is proposed and shown to work. A novel acoustic system excites rotor blade vibrations, which are measured with an optical tip-timing system. By performing measurements in an axial compressor, the potential of the acoustic excitation method for investigating aeroelastic effects is explored. The basic principle of this method is described and proven through the analysis of blade responses at different acoustic excitation frequencies and at different rotational speeds. To verify the accuracy of the tip-timing system, amplitudes measured by tip-timing are compared with strain gage measurements. They are found to agree well. Two approaches to vary the nodal diameter (ND) of the excited vibration mode by controlling the acoustic excitation are presented. By combining the different excitable acoustic modes with a phase-lag control, each ND of the investigated 30 blade rotor can be excited individually. This feature of the present acoustic excitation system is of great benefit to aeroelastic investigations and represents one of the main advantages over other excitation methods proposed in the past. In future studies, the acoustic excitation method will be used to investigate aeroelastic effects in high-speed turbomachines in detail. The results of these investigations are to be used to improve the aeroelastic design of modern turbomachines.

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Purpose: To assess the efficacy of the BARD scoring system in Saudi non‐alcoholic fatty liver disease (NAFLD) patients attending Gizan General Hospital and to identify the clinical variables associated with advanced fibrosis. . Methods: The cross-sectional study involved 120 patients aged ≥ 18 years who attended the Ultrasound Department of Gizan General Hospital, Gizan, Saudi Arabia, during January – June 2013. BARD scoring system comprised the following variables: body mass index (BMI) ≥ 28 = 1 point, aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio ≥ 0.8 = 2 points, and type 2 diabetes mellitus = 1 point. Results: Patients with advanced fibrosis were older (55.0 years) than patients with no/mild fibrosis (48.6 years), albeit not significantly so. A higher BMI was associated with advanced fibrosis in males, females and all study participants (p = 0.013, 0.016 and 0.001, respectively). Advanced fibrosis was more common in older patients with a higher weight to height ratio. Logistic regression suggested that age ≥ 50 years was associated with a 2.52-fold increase in the risk of advanced fibrosis, but this did not have a significant clinical impact (p = 0.087). BMI > 28 was associated with a 26.73-fold increased risk of advanced fibrosis, while AST/ALT ≥ 0.8 was associated with an 18.46-fold increased risk of advanced liver fibrosis (p = 0.002 and 0.006, respectively). Conclusion: The major risk factors for advanced fibrosis using BARD scoring system in patients with NAFLD were old age, BMI > 28, and AST/ALT ≥ 0.8. In addition, grade 3 ultrasonographic fatty liver significantly correlated with advanced fibrosis.