731 research outputs found

    Diffusivities bounds in the presence of Weyl corrections

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    In this paper, we investigate the behavior of the thermoelectric DC conductivities in the presence of Weyl corrections with momentum dissipation in the incoherent limit. Moreover, we compute the butterfly velocity and study the charge and energy diffusion with broken translational symmetry. Our results show that the Weyl coupling γ\gamma, violates the bounds on the charge and energy diffusivity. It is also shown that the Weyl corrections violate the bound on the DC electrical conductivity in the incoherent limit.Comment: v4: The appendix D and E were adde

    High-tech biomedical research: lessons from Iran's experience

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    Iran has recently made a significant progress in the field of biomedical science and launched an appreciable number of new high-tech biomedical research projects. Review of Iran's experience in advancing its biomedical research and the pitfalls the country encountered during the years of its progress could be of interest to other countries with similar technological conditions. As needs assessment and human resources have pivotal roles in any research infrastructure, here, we have delineated these factors and explored ways by which optimum advantage could be gained from them

    Application of Taguchi Approach to Forecast the Wages of Persian Silk Carpet Weavers

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    One of the remarkable phenomena in recent years is the growing trend of globalization. Iran is also seeking to join the World Trade Organization (WTO) to expand non-oil exports and presence in global markets, and is currently a member of the organization's oversight body. Handmade industries such as hand woven carpet are one of the important trades that can be studied for this purpose. Exports of handmade carpets have fluctuated over different time periods. Despite maintaining its international position as the rank of the largest exporter of handmade carpets, the export position of handmade carpets is decreasing as compared to other Iranian exports. Handmade carpet craftsmanship is a complementary activity of agricultural and rural businesses, but due to the considerable number of workers and the small share of carpet value added in the national economy, it does not have a suitable condition. Other influential parameters such as rivals (e.g., China, India, Pakistan, and Turkey), etc. have caused the economic conditions of this industry to be unstable. In this regard, one of the best and most appropriate ways to compete with other countries is to reduce production costs and, consequently, reduce product prices. This factor includes various variables, including weavers' wages. Unfortunately, there is no definite and elaborate program for determining the wages of handmade silk carpet weavers in Iran according to the standard. In fact, in some cities, the weavers' wages determine based on the texture conditions, texture parameters, economic conditions of the country, and other parameters by carpet wage boards that consist of several carpet experts. In this way, there is the possibility of mistakes and the loss of the rights of weavers or producers due to the entry of personal opinion and the failure to classify the effect of different parameters on the final point. The main purpose of this study is to collect various parameters affecting the wages of handmade carpet weavers in Iran. According to a collection of statistical data obtained from the country's most popular producers, the effects of different parameters were investigated through the Design of Experiment (DOE). Finally, the effect of each parameter was expressed as a percentage using Taguchi Approach (TA). The most important achievement of this research is that the obtained results can be used to prevent the loss of rights of the people by providing an appropriate formula and detail table

    Coincidence of Fixed Points with Mixed Monotone Property

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                  الغرض من هذا البحث استعراض واثبات النقاط الصامدة الثنائية للدوال الذاتية التي تحقق الشرط  مع التعابير النسبية في الفضاءات المترية الكاملة  المرتبة جزئيا والتي تتضمن دوال المسافة بخاصية ال (MP). تعمل النتائج التي حصلنا عليها على تحسين وتوحيد العديد من النتائج في مبرهنات النقطة الصامدة الثنائية وتعميم بعض النتائج الحديثة في الفضاء المتري المرتب جزئيا. تم إعطاء مثال لاظهار صحة نتيجتنا الرئيسية .The purpose of this paper is to introduce and prove some coupled coincidence fixed point theorems for self mappings satisfying -contractive condition with rational expressions on complete partially ordered metric spaces involving altering distance functions with mixed monotone property of the mapping. Our results improve and unify a multitude of coupled fixed point theorems and generalize some recent results in partially ordered metric space. An example is given to show the validity of our main result.

    Particules déterministes généralisées en filtrage non-linéaire : applications défense et télécommunications

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    La technique de filtrage particulaire s'applique à tous les problèmes d'estimation des systèmes dynamiques markoviens, sans restriction sur la nature des non-linéarités et/ou des distributions de bruits. L'objet de ce mémoire est de montrer la généralité de la technique déterministe en filtrage particulaire, par opposition à l'ancienne version aléatoire, qui permet d'éviter l'aléa inutilement introduit tant en prédiction qu'une redistribution des particules après pondération bayésienne. Le présent travail, s'articule autour de deux apports: Le premier, concerne le filtrage optimal à maximum de vraisemblance, et porte sur l'estimation trajectorielle globale des variables d'état. Le second portant sur le filtrage particulaire déterministe, concerne le filtrage optimal à minimum de variance, et porte sur l'estimation marginale à l'instant courant, par redistribution déterministe conforme en loi. Cette approche délivre simultanément tous les modes (maxima locaux) de la densité de probabilité marginale de l'état courant. Le mémoire met l'accent sur plusieurs réalisations dans des domaines différents, communications: Nous avons développé un outil à base de filtrage particulaire qui permet d'estimer conjointement des paramètres cinématiques relatifs au récepteur et la détection du message transmis par un satellite. Nous avons également proposé une série de schémas d'estimation/décodage itératifs du message turbo-codé conforme au standard DVB-RCS. Estimation de cible en sonar: On a construit un récepteur passif particulaire se contentant d'écouter sa cible, afin d'identifier ses paramètres cinématiques. La version déterministe permet de faire diminuer considérablement la masse de calculs. Traitement du signal radar: Le premier récepteur déterministe, à maximum de vraisemblance est utilisé pour la détection/poursuite de cibles furtives et manoeuvrantes, dans le cas où il y un nombre très limité de mesures disponibles pendant un tour d'antenne du radar de veille. Le second récepteur consiste à appliquer la technique à minimum de variance au radar ARMOR, ce qui a permis de confirmer des gains inhabituels en termes de rapport signal sur bruit. La nouvelle technique déterministe à minimum de variance s'étend également au multi-cible et au traitement en présence de fouillis, avec l'incomparable économie calculatoire du déterministe.Particle filters are presently among the most powerful tools to estimate Markovian dynamical systems, regardless of the nature of nonlinearities and/or noise probability distributions. The purpose of this dissertation is to show the generality of deterministic particle filtering, as opposed to the former random version, which avoids randomization in the prediction stage as well as in the resampling stage after Bayesian correction. This work relies on two kinds of results: the first concerns the particle filter-based maximum likelihood estimator for sequential estimation of the state variables. The second patent, introducing deterministic particle filtering in the minimum variance sense, focuses on the current state marginal estimation using a resampling scheme consistant with the a posteriori distribution. This approach simultaneously delivers all modes (local maxima) of the marginal probability density function of the current state. The thesis focuses on several achievements in various fields: communications: The proposed particle algorithm makes possible the joint estimation of the kinematic channel parameters at the receiver side and the detection of the message transmitted by a satellite. We have also proposed several techniques for the iterative estimation and decoding of the turbo-coded message compliant with the DVB-RCS standard. Target estimation for sonar: We built a passive particle receiver only listening to its target, in order to identify its kinematic parameters. The deterministic version allows to significantly reduce the computational complexity. Radar signal processing: The first receiver , with deterministic maximum likelihood filtering, is used for the detection / tracking of steady and manoeuvering targets , when there is a very limited number of available measurements during a circular period of antenna of the radar. The second receiver applies the minimum variance technique to the ARMOR radar, confirming unusually high signal-to-noise gains. The novel deterministic technique based on minimum variance criteria can easily be extended to multitarget processing and tracking in the presence of clutter, with the incomparable complexity savings due to the deterministic technique

    Doppler Frequency Estimation for a Maneuvering Target Being Tracked by Passive Radar Using Particle Filter

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    In this paper, we estimate Doppler frequency of a maneuvering target being tracked by passive radar using two types of particle filter, the first is “Maximum Likelihood Particle Filter” (MLPF) and the second is “Minimum Variance Particle filter” (MVPF). By simulating the passive radar system that has the bistatic geometry “Digital Video Broadcasting-Terrestrial (DVB-T) transmitter / receiver” with these two types, we can estimate the Doppler frequency of the maneuvering target and compare the simulation results for deciding which type gives better performanc

    Target Coordinates Estimation by Passive Radar with a Single non-Cooperative Transmitter and a Single Receiver

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    Passive radar is a bistatic radar that detects and tracks targets by processing reflections from non-cooperative transmitters. Due to the bistatic geometry for this radar, a target can be localized in Cartesian coordinates by using one of the following bistatic geometries: multiple non-cooperative transmitters and a single receiver, or a single non-cooperative transmitter and multiple receivers, whereas the diversity of receivers or non-cooperative transmitters leads to extra signal processing and a ghost target phenomenon. To mitigate these two disadvantages, we present a new method to estimate Cartesian coordinates of a target by a passive radar system with a single non-cooperative transmitter and a single receiver. This method depends on the ability of the radar receiver to analyze a signal-to-noise ratio (SNR) and estimate two arrival angles for the target’s echo signal. The proposed passive radar system is simulated with a Digital Video Broadcasting-Terrestrial (DVB-T) transmitter, and the simulation results show the efficiency of this system compared with results of other researches

    Finding Critical Element in the Progressive Collapse of RC Structures Using Sensitivity Analysis

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    Failure of some elements in the structure can play triggering role for beginning of collapse progression. The critical element is the structural element that when it fails, leads to progressive collapse. To find the critical element of the structure, sensitivity analysis should be done. But there are not specific structural criteria for using in sensitivity analysis. In this paper following GSA, UFC 4-023-03 and ASCE guidelines, sensitivity analysis has been modified and applied to find the critical element of a major number of reinforced concrete structures. 1080 3D nonlinear pushdown analyses were done and the results showed that the place of the critical elements differs in different stories and different plan shapes of high rise structures. In the structures with high aspect ratio in height, the critical element of the whole structure is located in the story of 2/3 height of the structure. When the aspect ratio of the structure in plan increases, sensitivity of the columns in the long dimension of the structure become closer to each other
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