A Novel Diversity Receiver Structure for Severe Fading and Frequency Offset Conditions

This paper presents a novel diversity receiver of MPSK signal in fading channel in the presence of the carrier frequency offset. As a part of this receiver, a new algorithm for the estimation of the combining coefficients (ECC algorithm) is introduced. Having in mind that the QPSK modulation is one of the most used modulation formats in many wireless communication standards (LTE, WiFi, WiMax), the performance of the proposed receiver is analyzed in more detail for the QPSK modulation. In the presence of Rayleigh fading, representing the most severe fading condition, this algorithm shows significantly better performance comparing to the same receiver structure that uses conventional constant modulus algorithm (CMA1 or CMA2). The proposed diversity receiver structure with ECC algorithm operates within a wide carrier frequency offset range with a very small variation of the performance. For this reason, it can be applied in 4G mobile communication systems

Određivanje dinamičnosti motornih vozila sa hidrodinamičkim prenosnikom snage

In process of projecting of vehicle transmission, which contains hydrodynamic power transmitter, is necessary to correct estimate stability of velocity action. It is also necessary to estimate other factors of transitional processes of unstationary fluid movement in their work area. Goal of this work is to determinate mathematical formulas that could be used for definition of physicality of dynamic processes in work area of hydrodynamic power transmitters.Pri projektovanju transmisije vozila, koja u svom sastavu ima hidrodinamički prenosnik snage neophodna je pravilna ocena stabilnosti brzine dejstva i drugih pokazatelja prelaznih procesa koji su povezani sa nestacionarnim kretanjem tečnosti u njihovom radnom prostoru. Cilj ovog rada je dolaženje do matematičkih izraza koji omogućavaju tačnije definisanje fizikalnosti dinamičkih procesa koji se odvijaju u radnim prostoru hidrodinamičkih prenosnika snage

Automatizacija procesa dijagnostike motornih vozila

Lately there are more and more effective objective methods for evaluation of technical condition of mobile systems, based on implementation of automatic diagnostic systems. Automatization of process of diagnostics significantly influences on the main indicators of effectiveness of used mobile systems. Owing to it, time for giving diagnosis is shorter, need for higher education of operator-diagnostician is reduced, costs of diagnostic process are decreased etc. Presentation of diagnostic results of technical condition of mobile systems is realized by application of modern devices with usage of adequate computer techniques. Automatization of diagnostics represents necessary basis for creation of information bases of subsystems of technical maintenance and repair, as well as important functional part of automatized system for management in companies with larger number of mobile systems. Automatization of means for measuring, converting and data processing enables simultaneous measuring of several different diagnostic parameters in different control points. Possibility to define average value of measured parameters and their analysis. Those possibilities for technical realization of diagnostic methods are unfeasible during classical measuring and analysis. Bearing in mind previously mentioned facts, aim of this work is to explain problems of automatization of diagnostics process of mobile systems, mainly by implementation of mathematical models of automatization of diagnostics process of mobile systems and by technical means of automatization of logical process of giving diagnosis.U poslednje vreme pojavljuje se sve više efikasnih objektivnih metoda ocene tehničkog stanja mobilnih sistema, zasnovanih na primeni automatskih dijagnostičkih sistema. Automatizacija procesa dijagnostike značajno utiče na osnovne pokazatelje efektivnosti korišćenih mobilnih sistema. Zahvaljujući njoj, značajno se skraćuje vreme uspostavljanja dijagnoze, smanjuje potreba za visokim obrazovanjem operateradijagnostičara, snižavaju troškovi procresa dijagnostike i td. Predstavljanje rezultata dijagnosticiranja tehničkog stanja mobilnih sistema ostvaruje se primenom savremenih uređaja uz korišćenje odgovarajuće računarske tehnike. Automatizacija procesa dijagnostike predstavlja neophodnu osnovu za stvaranje informacionih baza podsistema tehničkog održavanja i remonta, kao i važan funkcionalni deo automatizovanog sistema upravljanja u preduzećima sa većim brojem mobilnih sistema. Automatizovanjem sredstava merenja, pretvaranja i obrade podataka (informacija) omogućava se istovremeno merenje nekoliko različitih dijagnostičkih parametara u različitim kontrolnim tačkama, mogućnost osrednjavanja više vrednosti izmerenih parametarsa i njihovu analizu. Te mogućnosti tehničke realizacije rada dijagnostičkih metoda, u principu su neostvarljive pri klasičnom merenju i analizi. Imajući u vidu predhodno navedene činjenice, cilj ovog rada je da rasvetli problematiku automatizacije procesa dijagnosticiranja mobilnih sistema, prvenstveno preko primene matematičkih modela automatizacije procesa postavljanja dijagnoze i preko tehničkih sredstava automatizacije logičkog procesa postavljanja dijagnoze

Mogućnost određivanja optimalne periodičnosti preventivnog održavanja spojnice motornog vozila

As well, it is consider the possibility seeking trade off solution between this two criterions. With regular forming models of maintenance is possible to make optimisation, regarding, to use the best maintenance system. If the all important requests and limits are preciosly given then it is possible to solve this kind of problem. The base of presented metodology is presenting with reliability parameters of analysed vehicles given from vehicle behaviour folowing, from aspect of failure happen, in real conditions of exploatation and costs of theirs maintenance.Pravilnim formiranjem modela održavanja moguće je izvršiti optimizaciju, odnosno izabrati najpovoljniji sistem održavanja. Ovakav problem moguće je rešiti ako su precizno određeni svi važni zahtevi i ograničenja. Osnovu izložene metodologije čine parametri pouzdanosti analiziranih vozila, dobijeni na osnovu praćenja ponašanja vozila, sa aspekta pojave otkaza u realnim uslovima eksploatacije, kao i troškovi njihovog održavanja

The reactivity of 4'-substituted-biphenyl- 2-carboxylic acids with diazodiphenylmethane in various alcohols

85-8

Adaptive nonlinear output-feedback schemes with Marino-Tomei controller

Abs&mt-Three new adaptive nonlinear output-feedback schemes are presented. The first scheme employs the tuning functions design. The other two employ a novel estimation-based design consisting of a strengthened controller-observer pair and observer-based and swappingbased identifiers. They remove restrictive growth and matching conditions present in the previous output-feedback nonlinear estimation-based designs and allow a systematic improvement of transient performance

Magnetic Brightening of Carbon Nanotube Photoluminescence through Symmetry Breaking

Often a modification of microscopic symmetry in a system can result in a dramatic change in its macroscopic properties. Here we report that symmetry breaking by a tube-threading magnetic field can drastically increase the photoluminescence quantum yield of semiconducting single-walled carbon nanotubes, by as much as a factor of six, at low temperatures. To explain this striking connection between seemingly unrelated properties, we have developed a comprehensive theoretical model based on magnetic-field-dependent one-dimensional exciton band structure and the interplay of strong Coulomb interactions and the Aharonov-Bohm effect. This conclusively explains our data as the first experimental observation of dark excitons 5-10 meV below the bright excitons in single-walled carbon nanotubes. We predict that this quantum yield increase can be made much larger in disorder-free samples

Adaptive Tuning of Feedback Gain in Time-Delayed Feedback Control

We demonstrate that time-delayed feedback control can be improved by adaptively tuning the feedback gain. This adaptive controller is applied to the stabilization of an unstable fixed point and an unstable periodic orbit embedded in a chaotic attractor. The adaptation algorithm is constructed using the speed-gradient method of control theory. Our computer simulations show that the adaptation algorithm can find an appropriate value of the feedback gain for single and multiple delays. Furthermore, we show that our method is robust to noise and different initial conditions.Comment: 7 pages, 6 figure

Characterization of carbon fibrous material from platanus achenes as platinum catalysts support

Carbon materials with developed porosity are usually used as supports for platinum catalysts. Physico-chemical characteristics of the support influence the properties of platinum deposited and its catalytic activity. In our studies, we deposited platinum on carbon fibrous like materials obtained from platanus seeds - achenes. The precursor was chemically activated with different reagents: NaOH, pyrogallol, and H2O2, before the carbonization process. Platinum was deposited on all substrates to study the influence of the substrate properties on the activity of the catalyst. Carbon materials were characterized by nitrogen adsorption/desorption isotherms measurements, X-ray diffraction, and scanning electron microscopy. It was noticed that the adsorption characteristics of carbon support affected the structure of platinum deposits and thus their activity

Reversal of substituent effect on C=O stretching vibrations in hydantoin derivatives: Part II

1024-102