Circuital and Numerical Models for Calculation of Shielding Effectiveness of Enclosure with Apertures and Monitoring Dipole Antenna Inside

In this paper, circuital and numerical models of metal In this paper, circuital and numerical models of metal enclosure with apertures are considered for the purpose of accurate shielding effectiveness calculation. An improved circuital model is presented to account for the presence of receiving dipole antenna which is often used in practice to measure the level of electromagnetic field at selected points inside the enclosure. Receiving antenna of finite dimensions could significantly change the EM field distribution inside the enclosure and thus affect the results for SE. TLM method incorporating wire node is used to create a numerical model. Both models are compared in terms of their ability to account for receiving antenna impact on shielding effectiveness of rectangular enclosure with aperture. In addition, comparison of both models is carried out for the case when an array of apertures with different aperture separation is present on one of the enclosure walls whereby the numerical TLM model is additionally enhanced with compact air-vent model

On Drazin inverse of operator matrices

AbstractIn this short paper, we offer (another) formula for the Drazin inverse of an operator matrix for which certain products of the entries vanish. We also give formula for the Drazin inverse of the sum of two operators under special conditions

Quantum liquid crystals

The phenomenon of high temperature (high-Tc) superconductivity, although discovered 20 years ago, still remains mysterious. In conventional superconductors, the supercurrent is carried by a gas of weakly interacting pairs of electrons (Cooper pairs). Experiments suggest that the electron in high-Tc superconductors are at the verge of solidifying into a stripe-crystal, invalidating the conventional `gaseous' picture. Inspired by this problem, the work in this thesis offers an opposite paradigm for high-Tc superconductivity, based on the notion of the `almost ordered' superconductor. Formulating the problem in the field theoretical language of quantum elasticity and utilizing the duality transformation, quantum phases of matter are constructed which are as close as possible to a solid, which can be considered as quantum version of liquid crystals. We find that these ``dual shear superconductors'' are also genuine electromagnetic superconductors with properties which are however subtly different from conventional superconductors and invoke rather unconventional experiments: quantum-liquid crystalline orders, oscillations of magnetic screening currents, overscreening of Coulomb force, and especially a new collective mode found in the dynamical electromagnetic response.UBL - phd migration 201

Friction at Nanoscale

In many technical fields a contact between two surfaces is very important and often the subject of research. The numerous physical phenomena that occur at the contact between two materials indicate the complexity of the processes that take place at the macro, micro or nanoscale. Therefore, friction, lubrication and wear are the subjects that have been attracting attention for many years, especially as part of tribological investigations. The research has shown that these three components are of fundamental importance for surfaces in contact. The aim of this research is to describe friction, and lubrication as a process to control friction, especially at the atomic level. At the atomic and molecular scale there is a possibility to form very thin film with the property to spontaneously assemble themselves into ordered structures. One of the procedures to make these ultrathin organic films of controlled thickness is to prepare self-assembled monolayers. These monolayers are described as a model system to study boundary lubrication

Error bound of certain Gaussian quadrature rules for trigonometric polynomials

In this paper we give error bound for quadrature rules of Gaussian type for trigonometric polynomials with respect to the weight function w(x) = 1+cos x, x ∈ (−π, π), for 2π -periodic integrand, analytic in a circular domain. Obtained theoretical bound is checked and illustrated on some numerical examples

Error bound of certain Gaussian quadrature rules for trigonometric polynomials

In this paper we give error bound for quadrature rules of Gaussian type for trigonometric polynomials with respect to the weight function w(x) = 1+cos x, x ∈ (−π, π), for 2π -periodic integrand, analytic in a circular domain. Obtained theoretical bound is checked and illustrated on some numerical examples

On some interconnections between combinatorial optimization and extremal graph theory

The uniting feature of combinatorial optimization and extremal graph theory is that in both areas one should find extrema of a function defined in most cases on a finite set. While in combinatorial optimization the point is in developing efficient algorithms and heuristics for solving specified types of problems, the extremal graph theory deals with finding bounds for various graph invariants under some constraints and with constructing extremal graphs. We analyze by examples some interconnections and interactions of the two theories and propose some conclusions

Research of social networks in domain of tourism marketing

Predmet istraživanja disertacije je vezan za utvrđivanje uticaja društvenih mreža, kako tradicionalnih, tako i virtuelnih, na marketing i prodajnu funkciju organizacija, sa posebim akcentom na organizacije turističke delatnosti. Posebnu pažnju disertacija posvećuju definisanju naučne metodologije istraživanja društvenih mreža u funkciji marketinga usluga. Razvoj i uvođenje koncepta modela upravljanja društvenim mrežama poslovnih sistema, naročito je značajno u organizacijama turističke delatnosti. Na primeru zimskog turizma prikazana je implementacija predloženih metodoloških rešenja. Centralni problem koji se proučava vezan je za inkorporiranje tradicionalnih društvenih mreža u poslovni sistem organizatora putovanja i iskorišćavanje potencijala koje upravljanje ovako tretiranim, grupisanim i povezanim klijentima omogućava. U svrhu toga, svi poslovni procesi touroperatora su razloženi i sistematizovani po fazama, sa objašnjenjem uloge svake od tih faza u procesu upravljanja implementiranim društvenim mrežama postojećih i potencijalnih klijenata. U disertaciji će biti predstavljen Model upravljanja društvenim mrežama poslovnih sistema, pogotovo u uslužnom sektoru turizma.The object of research is identification of influence social networks, traditional as well as virtual, has on organization marketing and sales function with special attention on organization in tourist sector. Special attention of dissertation includes definition of the methodology of scientific research in domain of social networks in services marketing. Development and introduction of business system social network management conceptual model is of great importance for companies in tourism. Implementation of suggested methodological solutions is presented on winter tourism case. The main problem studied is incorporation of traditional social networks in business system of tour operator and exploitation of potential that treated, grouped and connected clients enables. In that case all the business processes of tour operators has been decomposed and systematized in stages with additional explanation of every stage in the process of implemented social networks management of existing and potential client’s. In dissertation there will be presented Model of Social Networks Management in organizations, especially in tourist service sector. Key words: Tourism, Tourism Marketing, Network Theory, Small World Theory, Social Networks, Social Groups, Virtual Social Network, Virtual Social Media, Model of Social Network Management, Principle of Authority Transfer, Authority of Relationship, Business Success Helix, Tour Operator, Snow Sport Industry, Ski Population, Segmentation of Ski Populatio

Advanced hardware control for seven DOFs robotic arm-neuro arm

In this paper we will implement new hardware control for 7 DOFs (Degrees of freedom) advanced robotic arm research platform (NeuroArm) equipped with various sensors. New hardware platform consists of Nano Pi platform which is used as a PC platform for standard PLC (programmable logic controller's) unit and will replace old system that consists of 7 16-bit ATmega processors. The goal of new PLC which is based on Linux operating system (Debian distribution) that is patched by Xenomai real time system for reducing control response time and better entire system control. Robotic arm is powered by 7 DC motors which are controlled by two PWM4 (Pulse Width Modulation) modules. Position data is acquired from 1kΩ resistive sensors using RI8 (Resistive module) module and from optical quadrature encoders using one DI16 (Digital Input) module. Also other modules PWM4, RI8 and DI16 communicate with PikoAtlas CPU module by I2C bus

Advanced hardware control for seven DOFs robotic arm-neuro arm

In this paper we will implement new hardware control for 7 DOFs (Degrees of freedom) advanced robotic arm research platform (NeuroArm) equipped with various sensors. New hardware platform consists of Nano Pi platform which is used as a PC platform for standard PLC (programmable logic controller's) unit and will replace old system that consists of 7 16-bit ATmega processors. The goal of new PLC which is based on Linux operating system (Debian distribution) that is patched by Xenomai real time system for reducing control response time and better entire system control. Robotic arm is powered by 7 DC motors which are controlled by two PWM4 (Pulse Width Modulation) modules. Position data is acquired from 1kΩ resistive sensors using RI8 (Resistive module) module and from optical quadrature encoders using one DI16 (Digital Input) module. Also other modules PWM4, RI8 and DI16 communicate with PikoAtlas CPU module by I2C bus