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Number of results: 77
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Abstract

The paper presents a heuristic approach to the problem of analog circuit diagnosis. Different optimization techniques in the field of test point selection are discussed. Two new algorithms: SALTO and COSMO have been introduced. Both searching procedures have been implemented in a form of the expert system in PROLOG language. The proposed methodologies have been exemplified on benchmark circuits. The obtained results have been compared to the others achieved by different approaches in the field and the benefits of the proposed methodology have been emphasized. The inference engine of the heuristic algorithms has been presented and the expert system knowledge-base construction discussed.
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Abstract

In the paper an application of evolutionary algorithm to design and optimization of combinational digital circuits with respect to transistor count is presented. Multiple layer chromosomes increasing the algorithm efficiency are introduced. Four combinational circuits with truth tables chosen from literature are designed using proposed method. Obtained results are in many cases better than those obtained using other methods.
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Abstract

One of the main problems of electrical power quality is to ensure a constant power ?ux from the supply system to the receiver, keeping in the same time the undisturbed wave form of the current and voltage signals. Distortion of signals are caused by nonlinear or time varying receivers, voltage changes or power losses in a supply system. The wave-form of the voltage of the source may also be deformed. This study seeks the optimal current and voltage wave-form by means of an optimization criteria. The optimization problem is de?ned in Hilbert space and the special functionals are minimized. The source inner impedance operator is linear and time-varying. Some examples of calculations are presented.
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Abstract

Demographic challenges of regional development of Poland. The goals of the article are dichotomous. First of all, it is the recognition of the main problems of regional development in Poland, resulting from the current and forecast demographic and settlement situation, including depopulation and population aging. An increasing mismatch between jobs, housing, education and services, increasingly scattered and inefficient settlement and inefficiency of the administrative and territorial system in terms of income and expenditure balancing and ensuring an adequate standard of services resulting from the administrative hierarchization of the settlement network, territorial delimitation and spatial accessibility have been identified. Then, in the second place, an attempt was made to formulate remedial measures related mainly to the optimization of spatial development and stimulation of innovative economic growth based in particular on endogenous poles of growth. In the article, among others the results of the author’s research and analyzes were used, which were carried out for practical purposes for government diagnostic and strategic documents in the years 2000–2017 [incl. “Report of the spatial development of Poland”, “Concept of Spatial Development of Poland 2030”, “National Strategy for Regional Development 2010–2020”, delimitation of “State Intervention Strategic Areas: Growth Areas and Problem Areas” and “Responsible Development Strategy”].
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Abstract

In order to enhance the acoustical performance of a traditional straight-path automobile muffler, a multi-chamber muffler having reverse paths is presented. Here, the muffler is composed of two internally parallel/extended tubes and one internally extended outlet. In addition, to prevent noise transmission from the muffler’s casing, the muffler’s shell is also lined with sound absorbing material. Because the geometry of an automotive muffler is complicated, using an analytic method to predict a muffler’s acoustical performance is difficult; therefore, COMSOL, a finite element analysis software, is adopted to estimate the automotive muffler’s sound transmission loss. However, optimizing the shape of a complicated muffler using an optimizer linked to the Finite Element Method (FEM) is time-consuming. Therefore, in order to facilitate the muffler’s optimization, a simplified mathematical model used as an objective function (or fitness function) during the optimization process is presented. Here, the objective function can be established by using Artificial Neural Networks (ANNs) in conjunction with the muffler’s design parameters and related TLs (simulated by FEM). With this, the muffler’s optimization can proceed by linking the objective function to an optimizer, a Genetic Algorithm (GA). Consequently, the discharged muffler which is optimally shaped will improve the automotive exhaust noise.
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Abstract

The article is devoted to the development of technogenic risk management models and formalization of the process of support in making decision in the sphere of industrial safety. The structural, informative and mathematical models, used to process information in the technological risks management, as well as a formal model of the process of support of making decision in achieving an acceptable level of technical risk are presented and analyzed.
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Abstract

Compact radiators with circular polarization are important components of modern mobile communication systems. Their design is a challenging process which requires maintaining simultaneous control over several performance figures but also the structure size. In this work, a novel design framework for multi-stage constrained miniaturization of antennas with circular polarization is presented. The method involves se- quential optimization of the radiator in respect of selected performance figures and, eventually, the size. Optimizations are performed with iteratively increased number of design constraints. Numerical efficiency of the method is ensured using a fast local-search algorithm embedded in a trust-region framework. The proposed design framework is demonstrated using a compact planar radiator with circular polarization. The optimized antenna is characterized by a small size of 271 mm2 with 37% and 47% bandwidths in respect of 10 dB return loss and 3 dB axial ratio, respectively. The structure is benchmarked against the state-of-the-art circular polarization antennas. Numerical results are confirmed by measurements of the fabricated antenna prototype.
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Abstract

This work examines the reduced-cost design optimization of dual- and multi-band antennas. The primary challenge is independent yet simultaneous control of the antenna responses at two or more frequency bands. In order to handle this task, a feature-based optimization approach is adopted where the design objectives are formulated on the basis of the coordinates of so-called characteristic points (or response features) of the antenna response. Due to only slightly nonlinear dependence of the feature points on antenna geometry parameters, optimization can be attained at a low computational cost. Our approach is demonstrated using two antenna structures with the optimum designs obtained in just a few dozen of EM simulations of the respective structure.
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Abstract

The paper analyzes the impact of potential changes in the price relation between domestic and imported coal and its influence on the volume of coal imported to Poland. The study is carried out with the application of a computable model of the Polish energy system. The model reflects fundamental relations between coal suppliers (domestic coal mines, importers) and key coal consumers (power plants, combined heat and power plants, heat plants, industrial power plants). The model is run under thirteen scenarios, differentiated by the ratio of the imported coal price versus the domestic coal price for 2020–2030. The results of the scenario in which the prices of imported and domestic coal, expressed in PLN/GJ, are equal, indicate that the volume of supplies of imported coal is in the range of 8.3–11.5 million Mg (depending on the year). In the case of an increase in prices of imported coal with respect to the domestic one, supplies of imported coal are at the level of 0.4–4.1 million Mg (depending on the year). With a decrease in the price of imported coal, there is a gradual increase in the supply of coal imports. For the scenario in which a 30% lower imported coal price is assumed, the level of imported coal almost doubles (180%), while the supply from domestic mines is reduced by around 28%, when compared to the levels observed in the reference scenario. The obtained results also allow for the development of an analysis of the range of coal imports depending on domestic versus imported coal price relations in the form of cartograms.
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Abstract

Internet of Things (IoT) will play an important role in modern communication systems. Thousands of devices will talk to each other at the same time. Clearly, smart and efficient hardware will play a vital role in the development of IoT. In this context, the importance of antennas increases due to them being essential parts of communication networks. For IoT applications, a small size with good matching and over a wide frequency range is preferred to ensure reduced size of communication devices. In this paper, we propose a structure and discuss design optimization of a wideband antenna for IoT applications. The antenna consists of a stepped-impedance feed line, a rectangular radiator and a ground plane. The objective is to minimize the antenna footprint by simultaneously adjusting all geometry parameters and to maintain the electrical characteristic of antenna at an acceptable level. The obtained design exhibits dimensions of only 3.7 mm × 11.8 mm and a footprint of 44 mm2, an omnidirectional radiation pattern, and an excellent pattern stability. The proposed antenna can be easily handled within compact communication devices. The simulation results are validated through measurements of the fabricated antenna prototype.
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Abstract

Re-design of a given antenna structure for various substrates is a practically important issue yet non trivial, particularly for wideband and ultra-wideband antennas. In this work, a technique for expedited redesign of ultra-wideband antennas for various substrates is presented. The proposed approach is based on inverse surrogate modeling with the scaling model constructed for several reference designs that are optimized for selected values of the substrate permittivity. The surrogate is set up at the level of coarse-discretization EM simulation model of the antenna and, subsequently, corrected to provide prediction at the high-fidelity EM model level. The dimensions of the antenna scaled to any substrate permittivity within the region of validity of the surrogate are obtained instantly, without any additional EM simulation necessary. The proposed approach is demonstrated using an ultra-wideband monopole with the permittivity scaling range from 2.2 to 4.5. Numerical validation is supported by physical measurements of the fabricated prototypes of the re-designed antennas.
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Abstract

In this paper, a novel structure of a compact UWB slot antenna and its design optimization procedure has been presented. In order to achieve a sufficient number of degrees of freedom necessary to obtain a considerable size reduction rate, the slot is parameterized using spline curves. All antenna dimensions are simultaneously adjusted using numerical optimization procedures. The fundamental bottleneck here is a high cost of the electromagnetic (EM) simulation model of the structure that includes (for reliability) an SMA connector. Another problem is a large number of geometry parameters (nineteen). For the sake of computational efficiency, the optimization process is therefore performed using variable-fidelity EM simulations and surrogate-assisted algorithms. The optimization process is oriented towards explicit reduction of the antenna size and leads to a compact footprint of 199 mm2 as well as acceptable matching within the entire UWB band. The simulation results are validated using physical measurements of the fabricated antenna prototype.
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Abstract

The paper deals with a composite element in which the matrix is reinforced with two families of parallel continuous fibres inclined to the x1 axis at the angles n1 and n2. The stress and strain states were determined in an element subjected to normal and tangential loads. The problem of two-criteria optimization is considered. Minimum strain energy and minimum cost of composite element were chosen as criteria. The strain energy is determined with respect to the system of principal axes of stress. Three independent variables: the angle directing the first family of fibres, the angle between two families and volume fraction of fibres are selected as the design variables. Examining particular load cases in composites made with epoxy resin reinforced with carbon fibres elements and in high performance fibre reinforced cementitious composite elements, optimum solutions have been determined in the sense of assumed criteria.
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Abstract

The paper presents optimization of power line geometrical parameters aimed to reduce the intensity of the electric field and magnetic field intensity under an overhead power line with the use of a genetic algorithm (AG) and particle swarm optimization (PSO). The variation of charge distribution along the conductors as well as the sag of the overhead line and induced currents in earth wires were taken into account. The conductor sag was approximated by a chain curve. The charge simulation method (CSM) and the method of images were used in the simulations of an electric field, while a magnetic field were calculated using the Biot–Savart law. Sample calculations in a three-dimensional system were made for a 220 kV single – circuit power line. A comparison of the used optimization algorithms was made.
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Abstract

The paper presents optimization of 5-rod (5-link) suspension mechanism used in passenger cars for independent guiding of the wheels. Selected stiffness coefficients defined for five elastomeric bushings installed in joints of the suspension rods are considered as design variables. Two models with lumped parameters (i.e. elastokinematic and dynamic) of wheel-suspension-car body system are formulated to describe relationships between the design variables and the performance indexes including car active safety and ride comfort, respectively. The multi-criteria goal function is minimized using a deterministic algorithm. The suspension with optimized bushings rates fulfils desired elastokinematic criteria together with a defined dynamic criterion, describing the so-called rolling comfort. An event of car passing over short road bump is considered as dynamic conditions. The numerical example deals with an actual middle-class passenger car with 5-rod suspension at the front driven axle. Estimation of the models parameters and their verification were carried out on the basis of indoor and outdoor experiments. The proposed optimization procedure can be used to improve the suspension design or development cycle.
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Abstract

Faithfull detection of non-utilized spectrum hole in available channel is a crucial issue for cognitive radio network. Choosing the best available channel for a secondary user transmission includes settling on decision of accessible choices of free frequency spectrum based on multiple objectives. Thus channel judgment can be demonstrated as several objective decision making (MODM) problem. An ultimate goal of this exploration is to define and execute a technique for multiple objective optimizations of multiple alternative of channel decision in Adhoc cognitive radio network. After a coarse review of an articles related to the multiple objective decision making within a process of channel selection, Multiple Objective Optimization on the basis of the Ratio Analysis (MOORA) technique is taken into consideration. Some important objectives values of non-utilized spectrum collected by a fusion center are proposed as objectives for consideration in the decision of alternatives. MOORA method are applied to a matrix of replies of each channel alternatives to channel objectives which results in set ratios. Among the set of obtained dimensionless ratios, all the channel alternatives are ranked in descending order. In MOORA, channel choices with moderate objectives can top in ranking order, which is hardly conceivable with linearly weighted objectives of the different channel by using different decision making technique.
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Abstract

Formation of modern landscapes of Zaporizhzhya region occurred in the Holocene period. During the Holocene wet phase changing climate fairly arid, warm - rather cold, but the average climatic indicators were close to modern. These conditions contributed to the formation of steppe zonal type of landscape. However, due to prolonged exposure to diverse steppe landscapes economic impacts associated with mismanagement of their natural potential and increasing human pressure on the natural environment has been transformed natural landscapes and change their properties. The result of this action was that the area landscapes drastically reduced. Zaporizhzhya region was the most economically mastered in all regions of Ukraine. To further study the issues to optimize environmental management of the region, the article reproduced a modern structure of landscapes area. The area characterized Zaporizhzhya region lowland class and type steppe landscapes. Three subtypes of landscapes: the north, middle and dry steppe. Each subtype is divided into land. Within North steppe subtype isolated Dniester-Dnieper and the Left-Bank Dnepr-Azov province. Medium steppe subtype is represented by the Black Sea margin, and dry steppe - Black sea-Azov. The most popular items on the optimization of environmental management are landscaped areas and areas of morphological units within them. That level reflects the nature of the landscape area inside the area landscape differentiation. Within the Zaporizhzhya region allocated 7 landscaped areas: highland Azov, highland-Dnieper south slope, Kinsko-Yalinska low-lying, low-lying Azov, the Dnieper-Molochansk low-lying, Western Azov-slope highland and lowland Prisivasko-Priazov.
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