A gravity independent vapor absorption refrigerator

Design evaluation of vapor absorbing refrigerator systems operating independently of gravit

Influence of the Polarity of the Electric Field on Electrorheometry

Uniaxial extensional flow is a canonical flow typically used in rheological characterization to provide complementary information to that obtained by imposing simple shear flow. In spite of the importance of having a full rheological characterization of complex fluids, publications on the rheological characterization of mobile liquids under extensional flow have increased significantly only in the last 20 years. In the case of the rheological characterization of electrorheological fluids, the situation is even more dramatic, as the ERFs have been exclusively determined under simple shear flow, where an electrorheological cell is attached to the rotational rheometer generating an electric field perpendicular to the flow direction and that does not allow for inverting the polarity. The very recent work published by Sadek et al., who developed a new electrorheological cell to be used with the commercial Capillary Breakup Extensional Rheometer (CaBER), allows for the very first time performing electrorheometry under extensional flow. By means of the same experimental setup, this study investigates the influence of the polarity of the imposed electric field on the filament thinning process of a Newtonian and an electrorheological fluid. Results show that a polarity against the gravity results in filament thinning processes that live longer or reach a stable configuration at lower intensities of the applied electric field

Analysis of Homogeneous Coplanar Strip Line

The goal of this work is to introduce a new, maybe complicated but in the final result mathematically simplest model of the coplanar strip line (CPS). In contrast to the usual method based on elliptical integrals the simplest circular inversion is applied. The main advantage is that our solution is mathematically less complicated but its accuracy is a little bit lower. The maximal error of the model described lies within the restricted interval between -3% and 3%. Nevertheless the final formula is useful for the practical engineering application

A text mining approach for Arabic question answering systems

As most of the electronic information available nowadays on the web is stored as text,developing Question Answering systems (QAS) has been the focus of many individualresearchers and organizations. Relatively, few studies have been produced for extractinganswers to “why” and “how to” questions. One reason for this negligence is that when goingbeyond sentence boundaries, deriving text structure is a very time-consuming and complexprocess. This thesis explores a new strategy for dealing with the exponentially large spaceissue associated with the text derivation task. To our knowledge, to date there are no systemsthat have attempted to addressing such type of questions for the Arabic language.We have proposed two analytical models; the first one is the Pattern Recognizer whichemploys a set of approximately 900 linguistic patterns targeting relationships that hold withinsentences. This model is enhanced with three independent algorithms to discover thecausal/explanatory role indicated by the justification particles. The second model is the TextParser which is approaching text from a discourse perspective in the framework of RhetoricalStructure Theory (RST). This model is meant to break away from the sentence limit. TheText Parser model is built on top of the output produced by the Pattern Recognizer andincorporates a set of heuristics scores to produce the most suitable structure representing thewhole text.The two models are combined together in a way to allow for the development of an ArabicQAS to deal with “why” and “how to” questions. The Pattern Recognizer model achieved anoverall recall of 81% and a precision of 78%. On the other hand, our question answeringsystem was able to find the correct answer for 68% of the test questions. Our results revealthat the justification particles play a key role in indicating intrasentential relations

A two dimensional fluid model for TCP/AQM analysis

This work proposes a new mathematical model for the TCP/AQM system that aims to improve the accuracy of existing fluid models, especially with respect to the sequential events that occur in the network. The analysis is based on the consideration of two time bases, one at the queue's router level and the other at the congestion window level, which leads to the derivation of a new nonlinear two-dimensional fluid model for Internet congestion control. To avoid the difficult task of assessing stability of a 2D nonlinear dynamic model, we perform a local stability analysis of a 2D linear TCP AQM model. By constructing a new two dimensional second order Bessel Legendre Lyapunov functional, new matrix inequalities are derived to evaluate the stability of the 0-input system and to synthesize a feedback controller. Finally, two Internet traffic scenarios, with state space matrices for replicability, are presented, demonstrating the validity of the theoretical results.Comment: Active queue management, network assisted congestion control, TCP/AQM, 2D time delay systems, Roesser model, 2D second order bessel Legendre, Lyapuno

Visečestične korelacije sivih čestica emitiranih u sudarima jezgra–jezgra

The short range correlation among emitted knock on nucleons from heavy ion collisions is used to reveal the dynamic characteristics of the reactions at high energy. Two- and three-particle correlations are considered in angular space to explain the emission of gray particles from collectively excited states of the nucleus as a Fermi liquid drop. Positive correlation is detected only among particles emitted in the extreme backward direction which is the coldest domain. It is interpreted as direct non-statistical emission (splashing) of nucleons via the dynamical distortion of the Fermi surface accompanying the collective motion.Proučavamo korelacije kratkog dosega izbijenih nukleona u sudarima teških iona radi upoznavanja dinamičkih značajki tih reakcija na visokim energijama. Razmatramo dvo- i tro-čestične kutne korelacije emitiranih sivih čestica iz kolektivnih uzbudnih stanja jezgre promatrane kao Fermijeva kapljica tekućine. Pozitivna se korelacija opaža samo u smjeru prema natrag što odgovara najhladnijem području jezgre. To se tumači kao izravna nestatistička emisija (zapljuskivanje) nukleona putem dinamičkog izobličenja Fermijeve površine pri kolektivnom gibanju u jezgri