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Search results for: POWER SUPPLY NETWORKS
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Single-phase power electronics transformer with active functions for smart grid
PublicationThis paper presents the control of one cell of a modular single-phase power electronics transformer with active functions for meeting the smart grid concept. In this way, the converter could be used not only as a conventional transformer but also for grid such as reactive power, harmonic elimination and energy storage. The topology of the cell is composed by a bidirectional converter with three stages: a half bridge in the input...
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Service time distribution influence on end-to-end call setup delay calculation in networks with Session Initiation Protocol
PublicationThe most important GoS parameter for networks with SIP protocol is end-to-end call setup delay. So far there were no coherent models allowing calculation of these parameters for networks with SIP protocol. Few models were developed but they are insufficient. In the paper we propose model which allows end-to-end call setup delay calculation for networks with SIP protocol. The model is using chain of M/G/1/K models and is applicable...
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Inverse and forward surrogate models for expedited design optimization of unequal-power-split patch couplers
PublicationIn the paper, a procedure for precise and expedited design optimization of unequal power split patchcouplers is proposed. Our methodology aims at identifying the coupler dimensions that correspond to thecircuit operating at the requested frequency and featuring a required power split. At the same time, thedesign process is supposed to be computationally efficient. The proposed methodology involves two typesof auxiliary models (surrogates):...
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Safety issues referred to induced sheath voltages in high-voltage power cables – case study
PublicationLoad currents and short-circuit currents in high-voltage power cable lines are sources of the induced voltages in the power cables’ concentric metallic sheaths. When power cables operate with single-point bonding, which is the simplest bonding arrangement, these induced voltages may introduce an electric shock hazard or may lead to damage of the cables’ outer non-metallic sheaths at the unearthed end of the power cable line. To...
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Design analysis of combined gas-vapour micro power plant with 30 kW air turbine
PublicationThe article presents basic results of the design analysis of a combined gas-vapour micro power plant with a waste-heat boiler without exhaust reheat, working in the vapour section in the Organic Rankine Cycle (ORC) system. The analysis concerned working media most frequently used in those types of power plants and planned to be used in future. The object of the analysis was a micro power plant with a 30 kW gas (air) turbine for...
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Design analysis of combined gas-vapour micro power plant with 30 kW air turbine
PublicationThe article presents basic results of the design analysis of a combined gas-vapour micro power plant with a waste-heat boiler without exhaust reheat, working in the vapour section in the Organic Rankine Cycle (ORC) system. The analysis concerned working media most frequently used in those types of power plants and planned to be used in future. The object of the analysis was a micro power plant with a 30 kW gas (air) turbine for...
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Modeling of Surface Roughness in Honing Processes by UsingFuzzy Artificial Neural Networks
PublicationHoning processes are abrasive machining processes which are commonly employed to improve the surface of manufactured parts such as hydraulic or combustion engine cylinders. These processes can be employed to obtain a cross-hatched pattern on the internal surfaces of cylinders. In this present study, fuzzy artificial neural networks are employed for modeling surface roughness parameters obtained in finishing honing operations. As...
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QoS Extensions for Flow-Awareness Networks
PublicationThe paper contains a description and research results of the proposal for distributed QoS extensions for Flow-Based Networking. These QoS extensions let the network accept or reject flows based on current network load and QoS promises for each of the flows. Proposed solution consists of two distributed components, each of them performing in every node, measurement system and access control. The solution could be applied in any...
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Quality Parameters in IMS/NGN Networks
PublicationThe Next Generation Network (NGN) architecture, including elements of the IP Multimedia Subsystem (IMS) concept, is a proposition of a telecommunication network dedicated to the needs of current and future information society. The main goal of NGN is to provide Quality of Service (QoS), for which proper network design is necessary with respect to among others standardized call processing performance parameters, including expected...
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Genetic ANFIS for scheduling in telecommunication networks
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<title>Intelligence in optical networks</title>
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Artificial Neural Networks for Comparative Navigation
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Neural Networks and the Evolution of Environmental Change
PublicationZmiany środowiskowe na Ziemii są odwieczne i liczą około 4 miliardy lat. Homo sapiens wpłynął na każdy aspekt środowiska ziemskiego w wyniku rozwoju ludzkości na przestrzeni ostatnich milionów lat. Ale nic tak nie wpłynęło na wzrost i szybkość zmian na Ziemi jak ludzka aktywność w ciągu ostatnich dwóch stuleci. Po raz pierwszy zmiany ekosystemów były tak intensywne i zachodziły na tka wielką skalę i z taką szybkością jak nigdy...
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Networks 2010 Conference in Warsaw, Poland
PublicationArtykuł sprawozdawczy z konferencji.
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Industrial computer networks and functional safety
PublicationW rozdziale monografii przedstawiono wybrane aspekty bezpieczeństwa funkcjonalnego na przykładzie przemysłowych sieci komputerowych stosowanych w obiektach infrastruktury krytycznej. Pierwszą cześć rozdziału poświęcono omówieniu klasycznych rozwiązań w zakresie sieci komputerowych. Drugą część rozdziału stanowi analiza przypadku typowej przemysłowej sieci komputerowej z uwzględnieniem aspektów bezpieczeństwa funkcjonalnego.
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The reliability of ring, star and hybrid networks
PublicationJednym z parametrów charakteryzującym jakość sieci jest jej niezawodność. Rozważono sieci o topologiach drzewiastych, gwiaździstych, pętlowych, wielo-pętlowych oraz mieszanych. Przyjęto następujący model uszkodzeń. Węzły oraz kanały sieci ulegają uszkodzeniom z określonym prawdopodobieństwem, uszkodzenia elementów sieci są od siebie statystycznie niezależne. Jako oceny niezawodności sieci przyjęto: średnią liczbę sprawnych par...
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Cost minimisation in multi-interface networks
PublicationPraca dotyczy problemu minimalizacji energii poprzez selektywne odłączanie urządzeń komunikacyjnych w wielointerfejsowych sieciach bezprzewodowych w taki sposób, by zapewnić realizację wymaganego grafu połączeń. Sformułowano problem optymalizacyjny, podano wyniki dotyczące jego trudności i zaproponowano algorytmy optymalizacyjne.
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Survivability issues in IP-MPLS networks.
PublicationW pracy przedstawiono model oceny przeżywalności sieci IP-MPLS zaimplementowanej bezpośrednio na optycznej sieci WDM. Założono zaplanowane z góry zabezpieczenia aktywności ścieżek od krańca do krańca przez ścieżki węzłowo-rozłączne dedykowane bądź współdzielone. Przyjęto, że naprawa sieci zaczyna się w warstwie IP, a następnie obejmuje ścieżki optyczne. Zadanie optymalizacji tras IP i ich odwzorowanie na ścieżki optyczne zdekomponowano...
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The methods of design reliable distributed networks
PublicationOpisano dwie metody projektowania niezawodnych sieci rozległych. W pierwszej metodzie przyjęto, że koszt konstrukcji każdego połączenia jest jednakowy, w drugiej koszty opisuje zadana macierz kosztów. Jako parametr niezawodnościowy przyjęto liczbę niezależnych dróg pomiędzy węzłami sieci. Pierwsza z metod jest metodą dokładną, druga heurystyczną. Zdefiniowano i oceniono błąd metody heurystycznej. Opublikowano wyniki otrzymane...
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Survivability issues in op-mpls networks
PublicationW pracy przedstawiono model oceny przeżywalności sieci IP-MPLS zaimplementowanej bezpośrednio na optycznej sieci WDM. Założono zaplanowane z góry zabezpieczenia aktywnych ścieżek od krańca do krańca przez ścieżki węzłowo-rozłączne dedykowane bądź współdzielone. Przyjęto, że naprawa sieci zaczyna się w warstwie IP, a następnie obejmuje ścieżki optyczne. Zadanie optymalizacji tras IP i ich odwzorowanie na ścieżki optyczne zdekomponowano...
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Modelling fatalities on regional road networks
PublicationDuring the last decade Poland’s road fatalities went down by 44%. The trend differs from region to region. Effective road safetymanagement in regions requires tools for forecasting road safety measures and identifying factors influencing road fatality numbers. Mathematical models can provide such tools. They take into account local characteristics such as: demography, economy, infrastructure and motorization. Such models could...
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Survivability analysis of scale-free networks
PublicationPraca dotyczy aspektów złośliwej kompromitacji stacji sieciowych poprzez epidemie wirusów komputerowych oraz ataki hackerskie. Opisano nowy autorski model analizy przeżywalności atakowanych sieci bezskalowych i ocenę metod zabezpieczeń. Pokazano wyniki modelowania efektywności środków powstrzymujących epidemie wirusów, polityk filtracji w ścianach ogniowych, efektywności blokowania adresów. Wszystkie wyniki są oryginalne i publikowane...
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Approximation of Fractional Order Dynamic Systems Using Elman, GRU and LSTM Neural Networks
PublicationIn the paper, authors explore the possibility of using the recurrent neural networks (RNN) - Elman, GRU and LSTM - for an approximation of the solution of the fractional-orders differential equations. The RNN network parameters are estimated via optimisation with the second order L-BFGS algorithm. It is done based on data from four systems: simple first and second fractional order LTI systems, a system of fractional-order point...
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Small power laboratory model and high power prototype of the four-level VSI
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Optimization of combined heat and power (CHP) market allocation: The case of Poland
PublicationCombined heat and power (CHP), that is production of electricity and useful heat in a single thermodynamic process, is a way of primary energy saving and emission reduction. Therefore, promotion of the electricity from high-efficiency cogeneration (CHP-E) was encouraged in the European Union. However, CHP-E promotion mechanisms proved low effectiveness in certain countries, like Poland, where the prices of certificates of origin...
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Analysis of the instantaneous power signal for bearing diagnostics -bearing damaged
Open Research DataThe attached dataset contains the measurement results of the instantaneous values of current and voltage, recorded during the diagnostics of a damaged bearing. Bearing diagnostics can be carried out based on the method, which relies on the measurement and analysis of the variability of the signal instantaneous power, defined as the product of instantaneous...
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Analysis of the instantaneous power signal for bearing diagnostics - bearing undamaged
Open Research DataThe attached dataset contains the measurement results of the instantaneous values of current and voltage, recorded during the diagnostics of an undamaged bearing. Bearing diagnostics can be carried out based on the method, which relies on the measurement and analysis of the variability of the signal instantaneous power, defined as the product of instantaneous...
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Optimal Rotating Receiver Angles Estimation for Multicoil Dynamic Wireless Power Transfer
PublicationThis study proposed an approach to dynamic wireless charging that uses a rotating receiver coil. Our simulation study focused on the verification of a novel way of increasing the coupling coefficient and power transfer stability by following the flux of the transmitting coils. To obtain the highest possible coupling by means of the FEM analysis, we studied the optimization of the trajectory of the angular velocity of the rotating...
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A Wideband Channel Model for Body Area Networks in Circular Metallic Indoor Environments
PublicationIn this paper, the wideband characterization of the propagation channel in circular metallic indoor environments is addressed, regarding Body Area Networks and 5G small cells, an analytical model for the dependence of the mean delay and the average delay spread on the circle radius, the working frequency and the distance between the transmitter and the receiver being proposed. The derivation of the model is initially done analytically,...
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Operation of the 900 MW power plant with the ORC supplied from three heat sources
PublicationThe chapter is aimed at utilisation of waste heat in the reference supercritical power plant in the manner to produce electricity in ORC installation. The waste heat is available in the form of a stream of hot water at 90°C, recovered from the exhaust gases in the amount of 200MW. Such low enthalpy heat source is rather insufficient to produce a good quality vapour to feed the ORC turbine. Therefore an original approach to increase...
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Numbers, Please: Power- and Voltage-Related Indices in Control of a Turbine-Generator Set
PublicationThis paper discusses the proper selection and interpretation of aggregated control performance indices values mirroring the quality of electrical energy generation by a turbine-generator set cooperating with a power system. Typically, a set of basic/classical and individual indices is used in energy engineering to ensure the mirroring feature and is related to voltage, frequency and active or reactive power deviations from their...
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Innovative Bidirectional Isolated High-Power Density On-Board Charge for Vehicle-to-Grid
PublicationThis paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm3, and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching,...
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Możliwości sterowania mocą bierną elektrowni wiatrowej : Reactive power control methods in wind parks
PublicationReferat poświęcony jest zagadnieniu sterowania mocą bierną w elektrowniach wiatrowych. W pierwszej części referatu opisano tło problemu sterowania mocą bierną w parkach wiatrowych, podano powody, dla których moc bierna powinna podlegać regulacji oraz zarysowano metody, które mogą być do niej użyte. W celu sprawdzenia proponowanych metod kompensacji, zbudowano model matematyczny elektrowni wiatrowej, którego poszczególne elementy...
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Effect of soil moisture on current-carrying capacity of low-voltage power cables
PublicationOne of the factors affecting current-carrying capacity of underground power cables is the thermal resistivity of soil. Its value in the close proximity of the cable is the most important, and for this reason, in some cases, the local soil is replaced with an another soil type or with a cement-sand mixture. The thermal resistivity of the soil is strongly affected by moisture, and in the case of a cement-sand mixture – as tested...
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Two- and three-dimensional elastic networks with rigid junctions: modeling within the theory of micropolar shells and solids
PublicationFor two- and three-dimensional elastic structures made of families of flexible elastic fibers undergoing finite deformations, we propose homogenized models within the micropolar elasticity. Here we restrict ourselves to networks with rigid connections between fibers. In other words, we assume that the fibers keep their orthogonality during deformation. Starting from a fiber as the basic structured element modeled by the Cosserat...
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Magnetic and capacitive couplings influence on power losses in double circuit high voltage overhead transmission line
PublicationPurpose – The paper aims to discuss problems of power and energy losses in a double-circuit overhead transmission line. It was observed from energymeters’ readings, that in such a line, active power losses can be measured as “negative”. The “negative” active power losses appear when the active power injected to the circuit is lower than the active power received at the circuit end. The purpose of this paper is to explain this phenomenon. Theoretical...
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COMPARATIVE EVALUATION OF FERRITE SHIELDING DESIGNS IN INDUCTIVE POWER TRANSFER SYSTEMS
PublicationWireless power transfer technology is becoming widespread in last few years. In comparison to conventional solutions this technology can significantly increase maintainability and safety of charging systems. From the other side there are list of factors that limit efficiency of wireless systems. One of them is low coupling between coils caused by comparably high leakage inductance in comparison to regular transformer.
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On the Usefulness of the Generalised Additive Model for Mean Path Loss Estimation in Body Area Networks
PublicationIn this article, the usefulness of the Generalised Additive Model for mean path loss estimation in Body Area Networks is investigated. The research concerns a narrow-band indoor off-body network operating at 2.45 GHz, being based on measurements performed with four different users. The mean path loss is modelled as a sum of four components that depend on path length, antenna orientation angle, absolute difference between transmitting...
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Impact of thermal backfill parameters on current-carrying capacity of power cables installed in the ground
PublicationProper design of power installations with the participation of power cables buried in homogeneous and thermally well-conductive ground does not constitute a major problem. The situation changes when the ground is non-homogeneous and thermally low-conductive. In such a situation, a thermal backfill near the cables is commonly used. The optimization of thermal backfill parameters to achieve the highest possible current-carrying capacity...
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The Influence of Cooperation on the Operation of an MPC Controller Pair in a Nuclear Power Plant Turbine Generator Set
PublicationThe paper discusses the problem of cooperation between multiple model predictive control (MPC) systems. This approach aims at improving the control quality in electrical energy generation and forms the next step in a series of publications by the authors focusing on the optimization and control of electric power systems. Cooperation and cooperative object concepts in relation to a multi MPC system are defined and a cooperative control...
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On the production of electricity in Poland using a geothermal binary power plant - A thermodynamic overview - Part I
PublicationPoland has a significant potential of geothermal energy. However, the high-temperature sources that are needed to drive power plants are found in relatively few places. Therefore, the objective of this paper is to consider any location in the northern part of Poland as a possible place to build a binary power plant. A scientific research was confirmed the existence of an elevated temperature gradient in this region. The hot rocks...
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Long-distance quantum communication over noisy networks without long-time quantum memory
PublicationThe problem of sharing entanglement over large distances is crucial for implementations of quantum cryptography. A possible scheme for long-distance entanglement sharing and quantum communication exploits networks whose nodes share Einstein-Podolsky-Rosen (EPR) pairs. In Perseguers et al. [Phys. Rev. A 78, 062324 (2008)] the authors put forward an important isomorphism between storing quantum information in a dimension D and transmission...
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Energy consumption estimation of low-power devices using an integrating coulombmeter
PublicationThe main problem in designing devices powered with Energy Harvesting is an estimation of energy demand of low-power devices as well as quantity of energy provided by the selected energy transducer in the assumed work conditions. Due to the work characteristic of each block of the device and properties of the measured signal, measurement is not trivial. The paper presents the proposal of the micro-charge measurement device based...
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Determination of Mechanical Energy Loss in Steady Flow by Means of Dissipation Power
PublicationWhen systems of simple geometry like pipes or regular channels are considered, the mechan- ical energy loss of the fluid flow can be expressed by local and longitudinal empirical energy loss coefficients. However, in the case of large spatially distributed objects, there are no simple approaches to this task. In practice, general recommendations addressing different types of objects are used, but they usually provide very coarse...
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The Idea of Using Bayesian Networks in Forecasting Impact of Traffic-Induced Vibrations Transmitted through the Ground on Residential Buildings
PublicationTraffic–induced vibrations may constitute a considerable load to buildings. In this paper, vibrations transmitted through the ground caused by wheeled vehicles are considered. This phenomenon may cause cracking of plaster, cracks in load-bearing elements or even, in extreme cases, collapse of the whole structure. Measurements of vibrations of real structures are costly and laborious. Therefore, the aim of the present paper is to...
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An Off-Body Narrowband and Ultra-Wide Band Channel Model for Body Area Networks in a Ferryboat Environment
PublicationIn the article an off-body narrowband and ultra-wide band channel model for body area networks in a ferryboat environment is described. Considering the limited number of publications there is a need to develop an off-body channel model, which will facilitate the design of radio links, both from the multimedia services provider and the security point of view, for body area networks in this atypical environment. A mobile heterogeneous...
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Evidence-Based Risk Management for Civil Engineering Projects Using Bayesian Belief Networks (BBN)
PublicationThe authors are seeking new methods for improving the efficiency of the investments associated with the maintenance and operation of existing civil engineering structures. It is demonstrated how the knowledge about the elements of construction and operation phases and their relationships, combined with monitoring data can be used for more effective management of the risks associated with civil engineering projects. The methodology...
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Empirical verification in industrial conditions of fracture mechanics models of cutting power prediction
PublicationA comparison of experimental results obtained in the industrial conditions at a sawmill located in the Baltic Natural Forest Region (PL) and theoretical cutting power consumption forecasted with the models which include work of separation (fracture toughness) in addition to plasticity and friction has been described. In computations of cutting power consumption during rip sawing of Scots pine wood (Pinus sylvestris L.) values of...
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Computer-aided Analysis of Induced Sheath Voltages in High Voltage Power Cable System
PublicationThis paper concerns the effect of configuration of high voltage power cables on induced voltages in their metallic sheaths. One, two or three cables per phase and phase sequence of the cables are considered. Computing of the voltages was performed for a normal operation and in case of earth fault. Various ways of the sheaths bonding are considered as well. Shock hazard and voltage stress of non-metallic outer sheath of cables are...
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Spectrum Sensing Based on Hybrid Spectrum Handoff in Cognitive Radio Networks
PublicationThe rapid advancement of wireless communication combined with insufficient spectrum exploitation opens the door for the expansion of novel wireless services. Cognitive radio network (CRN) technology makes it possible to periodically access the open spectrum bands, which in turn improves the effectiveness of CRNs. Spectrum sensing (SS), which allows unauthorized users to locate open spectrum bands, plays a fundamental part in CRNs....