395 research outputs found

    Developing Prognostic Models Using Duality Principles for DC-to-DC Converters

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    Within the field of Integrated System Health Management, there is still a lack of technological approaches suitable for the creation of adequate prognostic model for large applications whereby a number of similar or even identical subsystems and components are used. Existing similarity among a number of different systems, which are comprised of similar components but with different topologies, can be employed to assign the prognostics of one system to other systems using an inference engine. In the process of developing prognostics, this approach will thereby save resources and time. This paper presents a radically novel approach for building prognostic models based on system similarity in cases where duality principle in electrical systems is utilized. In this regard, unified damage model is created based on standard Tee/Pi models, prognostics model based on transfer functions, and remaining useful life (RUL) estimator based on how energy relaxation time of system is changed due to degradation. An advantage is that the prognostic model can be generalized such that a new system could be developed on the basis and principles of the prognostic model of other systems. Simple electronic circuits, dc-to-dc converters, are to be used as an experiment to exemplify the potential success of the proposed technique validated with prognostics models from particle filter

    Reliability enhanced EV using pattern recognition techniques

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    The following paper will contribute to the development of novel data transmission techniques from an IVHM perspective so that Electrical Vehicles (EV) will be able to communicate semantically by directly pointing out to the worst failure/threat scenarios. This is achieved by constructing an image-based data communication in which the data that is monitored by a vast number of different sensors are collected as images; and then, the meaningful failure/threat objects are transmitted among a number of EVs. The meanings of these objects that are clarified for each EV by a set of training patterns are semantically linked from one to other EVs through the similarities that the EVs share. This is a similar approach to wellknown image compression and retrieval techniques, but the difference is that the training patterns, codebook, and codewords within the different EVs are not the same. Hence, the initial image that is compressed at the transmitter side does not exactly match the image retrieved at the receiver's side; as it concerns both EVs semantically that mainly addresses the worst risky scenarios. As an advantage, connected EVs would require less number of communication channels to talk together while also reducing data bandwidth as it only sends the similarity rates and tags of patterns instead of sending the whole initial image that is constructed from various sensors, including cameras. As a case study, this concept is applied to DC-DC converters which refer to a system that presents one of the major problems for EVs

    Principle of Duality on Prognostics

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    The accurate estimation of the remaining useful life (RUL) of various components and devices used in complex systems, e.g., airplanes remain to be addressed by scientists and engineers. Currently, there area wide range of innovative proposals put forward that intend on solving this problem. Integrated System Health Management (ISHM) has thus far seen some growth in this sector, as a result of the extensive progress shown in demonstrating feasible and viable techniques. The problems related to these techniques were that they often consumed time and were too expensive and resourceful to develop. In this paper we present a radically novel approach for building prognostic models that compensates and improves on the current prognostic models inconsistencies and problems. Broadly speaking, the new approach proposes a state of the art technique that utilizes the physics of a system rather than the physics of a component to develop its prognostic model. A positive aspect of this approach is that the prognostic model can be generalized such that a new system could be developed on the basis and principles of the prognostic model of another system. This paper will mainly explore single switch dc-to-dc converters which will be used as an experiment to exemplify the potential success that can be discovered from the development of a novel prognostic model that can efficiently estimate the remaining useful life of one system based on the prognostics of its dual system

    The appearance of a compact jet in the soft-intermediate state of 4U 1543-47

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    Recent advancements in the understanding of jet-disc coupling in black hole candidate X-ray binaries (BHXBs) have provided close links between radio jet emission and X-ray spectral and variability behaviour. In 'soft' X-ray states the jets are suppressed, but the current picture lacks an understanding of the X-ray features associated with the quenching or recovering of these jets. Here we show that a brief, ~4 day infrared (IR) brightening during a predominantly soft X-ray state of the BHXB 4U 1543-47 is contemporaneous with a strong X-ray Type B quasi-periodic oscillation (QPO), a slight spectral hardening and an increase in the rms variability, indicating an excursion to the soft-intermediate state (SIMS). This IR 'flare' has a spectral index consistent with optically thin synchrotron emission and most likely originates from the steady, compact jet. This core jet emitting in the IR is usually only associated with the hard state, and its appearance during the SIMS places the 'jet line' between the SIMS and the soft state in the hardness-intensity diagram for this source. IR emission is produced in a small region of the jets close to where they are launched (~ 0.1 light-seconds), and the timescale of the IR flare in 4U 1543-47 is far too long to be caused by a single, discrete ejection. We also present a summary of the evolution of the jet and X-ray spectral/variability properties throughout the whole outburst, constraining the jet contribution to the X-ray flux during the decay.Comment: Accepted to MNRAS. 11 pages, 6 figure

    Growth parameters and mortality rates of Liza klunzingeri in the Iranian waters of the Persian Gulf and Oman Sea, using Length Frequency Data

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    The aim of the present study was to investigate the population dynamics of Liza klunzingeri, in Hormouzgan province waters located in northern coasts of the Persian Gulf and Oman Sea. This study was carried out from October 2007 to September 2008. Samples were collected from commercial stake traps. The relationship between weight and fork length was found to be W= 0.0214 F.L^2.8233 suggesting that Liza klunzingeri shows isometric growth. Length-based stock assessment using the FiSAT software package showed an asymptotic length (L∞) of 20.3cm FL and growth coefficient of 0.6.yr^-1. These results gave a growth performance index (ø) of 2.39. The total mortality coefficient was estimated to be 2.31, a natural mortality of 1.09 and fishing mortality of 1.22. The estimated total mortality which, in relative terms, is considered average (2.31.yr^-1), coupled with the currently observed exploitation rate of 0.52 for L. klunzingeri, estimated from the mortality rates, suggested that the species is moderately exploited

    Association between psychosocial distress with cardio metabolic risk factors and liver enzymes in a nationally-representative sample of Iranian children and adolescents: The CASPIAN-III study

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    Background: The present study was designed to evaluate association of psychosocial distress with cardio metabolic risk factors and liver enzymes in Iranian children and adolescents.Method: This nationwide study was conducted as the third survey of the school-based surveillance system that was conducted among 5593 school students, 10-18 years in Iran. High triglyceride (TG), high fasting blood sugar (FBS), high total cholesterol (TC), high low-density lipoprotein cholesterol (LDL-C), low high-density lipoprotein cholesterol (HDL-C), hypertension (HTN), generalized obesity and abdominal obesity were considered as cardio metabolic risk factors and alanine transaminase (ALT) and aspartate aminotransferase (AST) were considered as liver enzymes. Data were analyzed using multiple logistic regression (MLR) analysis.Result: Psychosocial distress was detected in2027 (71.2) of boys and 1759 (63.3) of girls. Among boys, the mean of LDL, AST and DBP were higher and the mean FBS and HDL were lowering those with psychiatric distress than their other counterparts. Girls with psychosocial distress had significantly higher mean of HDL and FBS than those without psychiatric distress. Psychosocial distress significantly increased the odds of high LDL (OR = 2.36, 95CI 1.53, 3.64), high FBS (OR = 1.23, 95CI 1.02, 1.49) and low HDL (OR = 1.65, 95CI 1.41, 1.95).Conclusion: Psychosocial distress in adolescents is associated with increased risk of some cardio metabolic risk factors. © 2014 Qorbani et al.; licensee BioMed Central Ltd

    Just compensation? The price of death and injury after the Rana Plaza garment factory collapse

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    The 2013 collapse of the Rana Plaza factory building in Dhaka, Bangladesh was the most deadly disaster in garment manufacturing history, with at least 1,134 people killed and hundreds injured. In 2015, injured workers and the families of those killed received compensation from global apparel brands through a $30 million voluntary initiative known as the Rana Plaza Arrangement. Overseen by the International Labour Organization (ILO), the Rana Plaza Arrangement awarded payments to survivors using a pricing formula developed by a diverse team of ‘stakeholders’ that included labour groups, multinational apparel companies, representatives of the Bangladesh government and local employers, and ILO actuaries. This article draws from anthropological scholarship on the ‘just price’ to explore how a formula for pricing death and injury became both the means and form of a fragile political settlement in the wake of a shocking and widely publicised industrial disaster. By unpacking the complicated ‘ethics of a formula’ (Ballestero 2015), I demonstrate how the project of creating a just price involves not two sets of values (ethical and financial) but rather multiple, competing values. This article argues for recognition of the persistence and power of these competing values, showing how they variously strengthen and undermine the claim that justice was served by the Rana Plaza Arrangement. This analysis reveals the deficiencies of counterposing ‘morality’ and ‘economy’ in the study of price by reflecting upon all elements of price as situated within political economy and history
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