Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 182

Liczba wyników na stronie
first rewind previous Strona / 10 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  Monte Carlo simulation
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 10 next fast forward last
EN
Monte Carlo simulation method of oil spill domains determination based on the probabilistic approach to the solution of this problem is proposed. A semi-Markov model of the process of changing hydro-meteorological conditions is constructed and its parameters are defined. The general stochastic model of oil spill domain movement for various hydro-meteorological conditions is described. Monte Carlo simulation procedure is created and applied to generating the process of changing hydro-meteorological conditions and the prediction of the oil spill domain movement impacted by these changes conditions.
EN
In the present paper, some imaging properties of nanoparticles-based contrast agents including gold, bismuth, and silver were assessed and compared with conventional (iodinated) contrast agent in spectral computed tomography (CT). A spectral CT scanner with photon-counting detectors (PCD) and 6 energy bins was simulated using the Monte Carlo (MC) simulation method. The nanoparticles were designed with a diameter of 50 nm at concentrations of 2, 4, and 8 mg/ml. Water-filled cylindrical phantom was modeled with a diameter of 10 cm containing a hole with a diameter of 5 cm in its center, where was filled with contrast agents. The MC results were used to reconstruct images. Image reconstruction was accomplished with the filtered back-projection (FBP) method with hamming filter and linear interpolation method. CT number and contrast-to-noise ratio (CNR) of all studied contrast materials were calculated in spectral images. The simulations indicated that nanoparticle-based contrast agents have a higher CT number and CNR than the iodinated contrast agent at the same concentration and for all energy bins. In general, gold nanoparticles produced the highest CT number and CNR compared to silver and bismuth nanoparticles at the same concentration. However, at low energies (below 80 keV), silver nanoparticles performed similarly to gold nanoparticles and at high energies (120 keV), bismuth nanoparticles can be a good substitute for gold nanoparticles.
EN
The purpose of this work was to develop and validate a Monte Carlo model for a Dual Source Computed Tomography (DSCT) scanner based on the Monte Carlo N-particle radiation transport computer code (MCNP5). The geometry of the Siemens Somatom Definition CT scanner was modeled, taking into consideration the x-ray spectrum, bowtie filter, collimator, and detector system. The accuracy of the simulation from the dosimetry point of view was tested by calculating the Computed Tomography Dose Index (CTDI) values. Furthermore, typical quality assurance phantoms were modeled in order to assess the imaging aspects of the simulation. Simulated projection data were processed, using the MATLAB software, in order to reconstruct slices, using a Filtered Back Projection algorithm. CTDI, image noise, CT-number linearity, spatial and low contrast resolution were calculated using the simulated test phantoms. The results were compared using several published values including IMPACT, NIST and actual measurements. Bowtie filter shapes are in agreement with those theoretically expected. Results show that low contrast and spatial resolution are comparable with expected ones, taking into consideration the relatively limited number of events used for the simulation. The differences between simulated and nominal CT-number values were small. The present attempt to simulate a DSCT scanner could provide a powerful tool for dose assessment and support the training of clinical scientists in the imaging performance characteristics of Computed Tomography scanners.
EN
The main aim of this research is to compare the results of the study of demand’s plan and standardized time based on three heuristic scheduling methods such as Campbell Dudek Smith (CDS), Palmer, and Dannenbring. This paper minimizes the makespan under certain and uncertain demand for domestic boxes at the leading glass company industry in Indonesia. The investigation is run in a department called Preparation Box (later simply called PRP) which experiences tardiness while meeting the requirement of domestic demand. The effect of tardiness leads to unfulfilled domestic demand and hampers the production department delivers goods to the customer on time. PRP needs to consider demand planning for the next period under the certain and uncertain demand plot using the forecasting and Monte Carlo simulation technique. This research also utilizes a work sampling method to calculate the standardized time, which is calculated by considering the performance rating and allowance factor. This paper contributes to showing a comparison between three heuristic scheduling methods performances regarding a real-life problem. This paper concludes that the Dannenbring method is suitable for large domestic boxes under certain demand while Palmer and Dannenbring methods are suitable for large domestic boxes under uncertain demand. The CDS method is suitable to prepare small domestic boxes for both certain and uncertain demand.
5
Content available Capital budget decision-making in logistics
EN
Background: Capital budgeting decisions in the logistics industry often combine three distinct characteristics. Firstly, they relate to capital assets- such as vehicles or equipment- being periodically replaced with different useful lives and efficiency features, and secondly, their performance is subject to particular operating and market risks. Lastly, externalities, such as regulatory interventions and technological evolution, also contribute to innovation- and thus also uncertainty- becoming a significant factor in logistics. Accordingly, this paper develops a valuation model which takes these characteristics into account and facilitates a robust decision-making process. Methods: In order to properly capture the specifics of the problem, the proposed model is based on an application of the Life Cycle Cost budgeting method benchmarked to an appropriate functional unit, combined with the Monte Carlo simulation and sensitivity analyses of relevant risk factors. Results: A realistic case study was developed, providing the necessary input parameters for the method's application. It was thus demonstrated that it provides useful and coherent resources for the decision-making process, including the tools needed to test various assumptions and determine project risks. Conclusions: The presented model and its solution provide results which are superior compared to conventional capital budgeting methods in terms of properly capturing the essential value-determining factors for a common type of problem encountered in logistics. They are also adequately comprehensive to be applied by practitioners in a real-life managerial setting.
PL
Wstęp: Decyzje kapitałowe budżetowe w logistyce często wyróżniają się trzema charakterystycznymi cechami. Są one powiązane z aktywami kapitałowymi, takimi ją pojazdy lub sprzęt, które są okresowo zastępowane, z różnymi okresami życia oraz z faktem, że ich działanie podlega operacyjnemu i rynkowemu ryzyku. Warunki zewnętrzne, takie jak uwarunkowania prawne, rozwój technologii, innowacyjność (wszystko wpływające na niepewność działania) są również istotnym czynnikiem wpływającym na postępowanie w obrębie logistyki. W pracy jest zaprezentowany opracowany model ewaluacji, biorący pod uwagę powyżej wymienione charakterystyki oraz ułatwiający rozbudowany proces podejmowania decyzji. Metody: W celu prawidłowego ujęcia specyfikacji problemu, proponowany model jest oparty na aplikacji metody budżetowania Life Cycle Cost w odniesieniu do odpowiedniej jednostki funkcjonalnej, w połączeniu z symulacją Monte Carlo and analizą wrażliwości istotnych czynników ryzyka. Wyniki: Zostało opracowane realistyczne studium przypadku, dostarczające niezbędnych danych wejściowych dla proponowanej metody analizy. Dostarczyło to przydatne spójne dane wejściowe dla procesu podejmowania decyzji, włączając w to narzędzia potrzebne do testowania różnych założeń oraz oceny podejmowanego ryzyka. Wnioski: Prezentowany model i jego rozwiązane dostarcza wyników porównywanych z konwencjonalnymi metodami budżetowania kapitałowego pod względem prawidłowego ujmowania czynników wartościowych dla powszechnie występujących problemów w logistyce. Można go stosować w szeroko pojętej praktyce zarządzania.
6
Content available remote Monte Carlo simulation approach to reliability analysis of complex systems
EN
The article presents new results concerned with general procedures and algorithms to assess the reliability of complex systems with various reliability structures. The analytical method and based on it the simulation method were used to estimate the reliability characteristics of the port grain transportation system. Finally, the general simulation algorithm was developed to evaluate the reliability characteristics of ageing complex systems. In this case, the systems operating processes were described by any distributions of sojourn times in operation states and the reliability functions of their components were modified in such a way that these components are not characterized by a "lack of memory". The application of this algorithm has been illustrated by the results for exemplary complex two-state systems.
PL
Artykuł przedstawia nowe wyniki w postaci ogólnych procedur i algorytmów symulacyjnych pozwalających oceniać niezawodność złożonych systemów o różnorodnych strukturach niezawodnościowych. Metody analityczna oraz oparta na niej metoda symulacji zostały zastosowane do oszacowania charakterystyk niezawodności portowego systemu transportu zboża. Ponadto zbudowany został ogólny algorytm pozwalający oceniać niezawodność starzejących się systemów złożonych, których procesy eksploatacyjne opisane są dowolnymi rozkładami czasów przebywania w stanach, natomiast dowolne funkcje niezawodności ich elementów są zmodyfikowane w ten sposób, że elementy te nie charakteryzują się „brakiem pamięci”. Zastosowanie tego algorytmu zostało zilustrowane wynikami dla wybranych złożonych systemów dwustanowych.
EN
A simulation model to evaluate risks in Power Systems including green Energy sources to generate electricity for electro mobility use is presented in the paper. The model allows to calculate risk indicator that characterize the performance of the Power Systems. The model considers the additional risks of wind and solar variability in the Power Systems, through wind farms and PV farms, respectively. Also, in the recent years, the number of electric vehicles (EVs) on the road have been rapidly increasing. Charging this increasing number of EVs is expected to have an impact on the power grid especially if high charging powers and opportunistic charging are used. Multiple papers have observed that the charging stations are used by multiple users during the day. In a context where electric mobility is gaining increasing importance as a more sustainable solution for urban environments, this work presents the optimization of charging profiles of the potential users of these charging stations. We analyzed the charging profiles in a power grid with renewables sources of energy and we determine the optimal charging profiles for the power grid based on maximizing the energy delivered by renewable sources of energy.
EN
Simulation methods commonly used throughout the design and verification process of various types of motor vehicles require development of naturalistic driving cycles. Optimization of parameters, testing and gradual increase in the degree of autonomy of vehicles is not possible based on standard driving cycles. Ensuring representativeness of synthesized time series based on collected databases requires algorithms using techniques based on stochastic and statistical models. A synthesis technique combining the MCMC method and multifractal analysis has been proposed and verified. The method allows simple determination of the speed profile compared to classic frequency analysis.
PL
Metody symulacyjne powszechnie stosowane w całym procesie projektowania i weryfikacji różnych typów pojazdów mechanicznych wymagają opracowania eksploatacyjnych cykli jezdnych. Optymalizacja parametrów, testowanie i stopniowe zwiększanie stopnia autonomiczności pojazdów nie jest możliwe na bazie standardowych cykli jezdnych. Zapewnienie reprezentatywności syntezowanych szeregów czasowych na podstawie zgromadzonych baz danych wymaga algorytmów wykorzystujących techniki bazujące na modelach stochastycznych i statystycznych. Zaproponowano i zweryfikowano technikę syntezy łączącą metodę Monte Carlo wykorzystującą łańcuch Markowa (MCMC) oraz analizę multifraktalną. Metoda umożliwia proste wyznaczenie profilu prędkości jazdy w porównaniu do klasycznej analizy częstotliwościowej.
EN
Phased-mission system (PMS) is the system subject to multiple, consecutive and non-overlapping tasks. Much more complicated problems will be confronted when the PMS is repairable since the repairable system could perform the multi-phases mission with more diversity requirements. Besides, various maintenance strategies will directly influence the reliability analysis procedure. Most researches investigate those repairable PMSs that carry out the multi-phases mission with deterministic phase durations, and the mission fails once the system switches from up to down. In this case, one common maintenance strategy is that failed components are repairable as long as the system keeps in up state. However, many practical systems (e.g., construction machinery, agricultural machinery) may be involved in such multi-phases mission, which has uncertain phase durations but limited by a maximum mission time, within which failed components can be unconditional repaired, and the system can be restored from down state. Comparing with the former type of repairable PMS, the latter will also concern phase durations dependence, and both the system and components included have the state bidirectional transition. This paper makes new contributions to the reliability assessment of repairable PMSs by proposing a novel SEFT-MC method. Two types of repairable PMS mentioned above are considered. In our method, a specific sequence-enforcing fault tree (SEFT) is proposed to correctly depict failure logical relationships between the system and components included. In order to transfer the graphical fault tree (no matter its size and complexity) into a modular reliability model used in Monte Carlo (MC) simulation, an improved linear algebra representation (I-LAR) approach is introduced. Finally, a numerical example including two cases corresponding to the two types of repairable PMS is presented to validate the proposed method.
PL
System z misjami okresowymi (phased-mission system, PMS) to system, który wykonuje wiele następujących po sobie i nienakładających się na siebie zadań. W przypadku naprawialnych systemów PMS, analiza niezawodności jest o wiele bardziej skomplikowana, ponieważ system naprawialny może wykonywać misje wielofazowe o bardziej różnorodnych wymaganiach. Poza tym systemy takie wymagają zastosowania różnych strategii utrzymania ruchu, co ma bezpośredni wpływ na procedurę analizy niezawodności. Większość badaczy bada naprawialne systemy PMS, które wykonują misje wielofazowe, w których czas trwania fazy jest wielkością deterministyczną, a misja kończy się niepowodzeniem, gdy system przechodzi ze stanu zdatności do stanu niezdatności W takich przypadkach najczęściej przyjmuje się, że uszkodzone elementy można naprawić o ile system pozostaje w stanie zdatności. Jednak wiele systemów stosowanych w praktyce (t.j. maszyny budowlane czy maszyny rolnicze) może wykonywać misje wielofazowe, w których czas trwania fazy jest wielkością niepewną, ograniczoną jedynie przez maksymalny czas trwania misji, w którym to czasie uszkodzone komponenty mogą być bezwarunkowo naprawiane, dzięki czemu system może zostać przywrócony do stanu zdatności. W porównaniu z pierwszym rodzajem naprawialnego PMS, w drugim, czasy trwania faz są zależne od siebie. Ponadto, w systemie tego typu, zarówno poszczególne elementy, jak i cały system mogą przechodzić ze stanu zdatności do stanu niezdatności i odwrotnie. Niniejsza praca wnosi nowy wkład w ocenę niezawodności naprawialnych systemów PMS, proponując nowatorską metodę, która polega na wykorzystaniu dynamicznego drzewa niezdatności do przeprowadzenia symulacji Monte Carlo (SEFTMC). Rozważane są dwa wymienione powyżej typy naprawialnego PMS. W naszej metodzie zaproponowano drzewo niezdatności z bramkami SEQ (SEFT), które pozwala poprawnie zobrazować logiczne zależności między systemem a jego komponentami w zakresie uszkodzeń. Do przeniesienia graficznego drzewa niezdatności (bez względu na jego rozmiar i złożoność) do modułowego modelu niezawodności wykorzystywanego w symulacji Monte Carlo, zastosowano udoskonaloną metodę reprezentacji algebry liniowej (I-LAR). Poprawność proponowanej metody wykazano na przykładzie numerycznym obejmującym dwa przypadki odpowiadające dwóm omawianym typom naprawialnego PMS
EN
The mechanical interface has the characteristics of low shock and vibration, and is emphasized in the aerospace and ocean engineering fields. In this paper, a mechanical interface based on coupled cylindrical cam mechanisms is designed. It can achieve the expected functions, but there exist faults in some times. The fault modes and causes of the interface are firstly analyzed. Then a design approach based on Monte Carlo simulation is presented for analyzing and optimizing its reliability. According to the fault modes, the performance functions of the interface are established for obtaining the optimal scheme. A case is given to illustrate the proposed method. The simulation results and the prototype experiments prove that the optimization scheme effectively improves the reliability of the interface, and has better performance than the original one.
EN
The main objective of this paper is to model an offshore oil production system subjected to age-based preventive maintenance strategies by Petri Nets and to evaluate its availability by Monte Carlo Simulation. The oil processing and the separation equipment with their reliability and maintainability characteristics, the corrective and preventive maintenance policies and the operational dependencies that lead to the reconfiguration of the system after the failure are implemented. A special attention is given to the effect of age-based perfect and imperfect preventive maintenance strategies on the system availability. The maintenance actions consider the components’ age thresholds and an age reduction ratio. Moreover, the variation of the oil and gas flows from the well over the years is accounted by the model. As case study, an offshore production installation that operates in a Brazilian oilfield is adopted. An elasticity analysis on the model parameters is conducted to assess influence of the maintenance policy on the system availability and on the oil production.
EN
This research examines the probabilistic safety assessment of the historic BISTOON arch bridge. Probabilistic analysis based on the Load-Resistance model was performed. The evaluation of implicit functions of load and resistance was performed by the finite element method, and the Monte-Carlo approach was used for experiment simulation. The sampling method used was Latin Hypercube. Four random variables were considered including modulus of elasticity of brick and in filled materials and the specific mass of brick and infilled materials. The normal distribution was used to express the statistical properties of the random variables. The coefficient of variation was defined as 10%. Linear behavior was assumed for the bridge materials. Three output parameters of maximum bridge displacement, maximum tensile stress, and minimum compressive stress were assigned as structural limit states. A sensitivity analysis for probabilistic analysis was performed using the Spearman ranking method. The results showed that the sensitivity of output parameters to infilled density changes is high. The results also indicated that the system probability of failure is equal to rhofsystem=1,55x10-3. The bridge safety index value obtained is betat=2.96, which is lower than the recommended target safety index. The required safety parameters for the bridge have not been met and the bridge is at the risk of failure.
EN
The purpose of this paper is to investigate the effects of natural uncertainties and effective parameters on the stability of plate-type rock walls. For this, the effective factors and geo-mechanical properties in the study area were obtained using field experiments. Stability analysis of rock walls was investigated for 40 scenarios in dry and saturated states. These parameters were then evaluated using Easyfit software and Markov chain analysis and Monte Carlo simulation by Rock Plane software. Comparison of the results of numerical and uncertainty methods shows that the rock walls with 60-80 degree slope are stable; and In saturated state they require stability due to the reduction of shear strength. Fixation of the rock walls was also investigated, indicating an optimum angle of 30° for the installation of the rock screw. The results show that the Monte Carlo simulation provides a simpler interpretation and the uncertainty methods are more accurate and reliable than the numerical methods.
EN
This paper concerns load testing of typical bridge structures performed prior to operation. In-situ tests of a two-span post-tensioned bridge loaded with three vehicles of 38-ton mass each formed the input of this study. On the basis of the results of these measurements an advanced FEM model of the structure was developed for which the sensitivity analysis was performed for chosen uncertainty sources. Three uncorrelated random variables representing material uncertainties, imperfections of positioning and total mass of loading vehicles were indicated. Afterwards, two alternative FE models were created based on a fully parametrised geometry of the bridge, differing by a chosen global parameter – the skew angle of the structure. All three solid models were subjected to probabilistic analyses with the use of second-order Response Surface Method in order to define the features of structural response of the models. It was observed that both the ranges of expected deflections and their corresponding mean values decreased with an increase of the skewness of the bridge models. Meanwhile, the coefficient of variation and relative difference between the mean value and boundary quantiles of the ranges remain insensitive to the changes in the skew angle. Owing to this, a procedure was formulated to simplify the process of load testing design of typical bridges differing by a chosen global parameter. The procedure allows - if certain conditions are fulfilled - to perform probabilistic calculations only once and use the indicated probabilistic parameters in the design of other bridges for which calculations can be performed deterministically.
PL
Pracę otwiera przegląd najnowszej literatury fachowej o zasięgu międzynarodowym, dotyczącej próbnych obciążeń obiektów mostowych. W licznych publikacjach badawczych jednoznacznie stwierdzono, iż zasadne jest, by często stosowane w tym zakresie metody deterministyczne uzupełniać lub zastępować analizami probabilistycznymi. Niniejsza praca stanowi zatem rozwinięcie dotychczasowych osiągnięć i spostrzeżeń. Przedmiotem pracy jest analiza możliwości zwiększenia efektywności procesu przygotowania probabilistycznych projektów próbnych obciążeń typowych konstrukcji mostowych, różniących się wybranym parametrem geometrycznym (w tym przypadku – kątem ukosu konstrukcji „α”) przed ich dopuszczeniem do eksploatacji w zakresie pomiarów statycznych. Punktem wyjściowym przedstawionej analizy jest próbne obciążenie in-situ typowego, drogowego mostu sprężonego. Jednym z podstawowych kryteriów dopuszczenia obiektu mostowego do użytkowania w niektórych krajach, jest wykazanie, iż ugięcia dźwigarów głównych obiektu mostowego wywołane statycznym obciążeniem próbnym są mniejsze niż te określone teoretycznie w modelu MES obiektu. W pierwszej kolejności zatem, wyniki pochodzące z rzeczywistych badań próbnego obciążenia zostały zestawione z ich teoretycznymi odpowiednikami, pochodzącymi z prostego modelu rusztowego mostu. Ten przykład ogranicza się do analizy maksymalnych ugięć jednego z dźwigarów głównych obiektu. Wykazano, iż ugięcia z pomiarów in-situ (pomierzone przemieszczenia zostały odpowiednio przeliczone na ugięcia, aby uwzględnić wpływ osiadania podpór i zgniotów łożysk) były mniejsze niż te określone teoretycznie. Nie było zatem podstaw do niedopuszczenia mostu do użytkowania ze względu na niespełnienie kryterium ugięć. Jednakże, w rezultacie analizy wykazano, iż wyniki odpowiedzi konstrukcji z prostego modelu deterministycznego różniły się znacznie od wyników pomiarów. W związku z tym, w celu opracowania procedury zwiększenia efektywności procesu przygotowywania probabilistycznych projektów próbnych obciążeń obiektów typowych, do dalszych analiz porównawczych i probabilistycznych wygenerowany został znacząco bardziej zaawansowany model bryłowy MES.
EN
The article presents the methodology of controlling stock of spare parts during short-run production of current equipment. A pseudo-random number generator has been developed, whose main task is to estimate the expected value E (Y) of the random variable Y which is the number of exchanges of a spare part of a particular equipment. By means of a Monte Carlo computer simulation, pseudo-random numbers are generated with a uniform distribution from the interval (0.1). These numbers, based on the cumulative distribution inversion method, are transformed into a form of distribution that uniquely determines the optimal size of spare parts.
EN
According to the European Environment Agency (EEA 2018), air quality in Poland is one of the worst in Europe. There are several sources of air pollution, but the condition of the air in Poland is primarily the result of the so-called low-stack emissions from the household sector. The main reason for the emission of pollutants is the combustion of low-quality fuels (mainly low-quality coal) and waste, and the use of obsolete heating boilers with low efficiency and without appropriate filters. The aim of the study was to evaluate the impact of measures aimed at reducing low-stack emissions from the household sector (boiler replacement, change of fuel type, and thermal insulation of buildings), resulting from environmental regulations, on the improvement of energy efficiency and the emission of pollutants from the household sector in Poland. Stochastic energy and mass balance models for a hypothetical household, which were used to assess the impact of remedial actions on the energy efficiency and emission of pollutants, have been developed. The annual energy consumption and emissions of pollutants were estimated for hypothetical households before and after the implementation of a given remedial action. The calculations, using the Monte Carlo simulation, were carried out for several thousand hypothetical households, for which the values of the technical parameters (type of residential building, residential building area, unitary energy demand for heating, type of heat source) were randomly drawn from probability distributions developed on the basis of the analysis of the domestic structure of households. The model takes the coefficients of correlation between the explanatory variables in the model into account. The obtained results were multiplied so that the number of hypothetical households was equal to 14.1 million, i.e. the real number of households in Poland. The obtained results allowed for identifying the potential for reducing the emission of pollutants such as carbon dioxide, carbon monoxide, dust, and nitrogen oxides, and improving the energy efficiency as a result of the proposed and implemented measures, aimed at reducing low-stack emission, resulting from the policy. The potential for emissions of gaseous pollutants is 94% for CO, 49% for NOx, 90% for dust, and 87% for SO2. The potential for improving the energy efficiency in households is around 42%.
PL
Celem pracy była ocena wpływu działań zmierzających do obniżenia niskiej emisji w gospodarstwach domowych (wymiana kotłów, zmiana rodzaju paliwa, docieplenie budynków) wynikających z regulacji prawnych w zakresie ochrony środowiska na poprawę efektywności energetycznej i emisję polutantów w sektorze gospodarstw domowych w Polsce. Zbudowano stochastyczne modele bilansu energii i masy dla hipotetycznego gospodarstwa domowego, które zostały wykorzystane do oceny efektywności energetycznej i emisji polutantów realizacji działań wynikających z prawodawstwa. Dla hipotetycznych gospodarstw domowych oszacowane zostało roczne zużycie energii i emisji polutantów przed wdrożeniem danej regulacji i po jej wdrożeniu. Wykorzystując symulację Monte Carlo obliczenia zostały przeprowadzone dla kilku tysięcy hipotetycznych gospodarstw domowych, dla których wartości parametrów technicznych (liczba osób w gospodarstwie, sposób przygotowania ciepłej wody użytkowej i ogrzewania budynku, rodzaj paliwa, wiek i klasa energetyczna budynku, powierzchnia i lokalizacja budynku) były losowane z rozkładów prawdopodobieństwa przygotowanych na podstawie analizy struktury krajowej gospodarstw domowych. Otrzymane wyniki zwielokrotniono tak, aby liczba hipotetycznych gospodarstw była równa 14,1 mln, tj. rzeczywistej liczbie gospodarstw domowych w Polsce. Otrzymane wyniki pozwoliły określić potencjał w zakresie ograniczenia emisji polutantów takich jak CO2, CO, pyły oraz NOx i poprawy efektywności energetycznej w wyniku proponowanych i realizowanych działań zmierzających do ograniczenia niskiej emisji wynikających z regulacji prawnych. Potencjał emisję zanieczyszczeń gazowych sięga ponad 94%, natomiast potencjał w zakresie poprawy efektywności energetycznej w gospodarstwach domowych wynosi około 42%.
EN
This study aims to investigate and evaluate the secondary photons characterizations under flattening filter (FF) for high radiotherapy quality in terms of fluence, energy fluence, energy fluence distribution, spectral distribution and angular spread distribution of secondary photons, which are mainly coming from primary collimator originated in the whole Linac head. However, the flattening filter illuminates the photons of low energy. After this component, the secondary photons of low energy are coming from flattening filter and secondary collimators that contaminate the dosimetry for deep tumor treatment. Fluence profile, energy profile and angular spread of secondary photons decreased with FF volume reduction percent but energy distribution and spectral distribution kept almost constant with FF volume reduction. The FF volume reduction allows reducing the secondary photons emergent from FF in number and in energy and it permits to increase the radiotherapy efficiency by decreasing the photons contamination when the cancer is treating.
EN
Radiation education is necessary for a wide variety of people, such as radiation workers particularly for students of secondary school and higher education institution who learn radiation sciences. The fact that we could not see or feel radiation makes it difficult to understand it. The use of radiation trajectories shown on a personal computer should be useful to overcome this difficulty. In order to understand radiation behaviour inside the material, we have developed a Simu-Rad (Copyright: LY2018002738) by using Monte Carlo simulation programme. One who has no programming knowledge is able to simulate photons in a material through the developed programme. The program could become a computer aided learning tool for radiation related courses. We aim to facilitate lecturer from ‘The Traditional Classroom’ to ‘The Flipped Classroom’ for radiation education concerning in the era of IR 4.0. To validate our radiation simulator, we calculate photon linear attenuation coefficient (µ) of an aluminium material which commonly used as a filter in diagnostic radiology. µ is one of the main characteristics to understand how the radiation attenuated inside the materials. We calculate at energy photon of 662 keV (Cs-137 radiation source) to compare our results of µ with the XCOM database. Consequently, the results from the developed simulator comparable with the database verified our programme to be used for radiation study.
19
EN
Background: Recently bismuth-based nanoparticles have attracted increasing attention as a dose amplification agent in radiation therapy due to high atomic number, high photoelectric absorption, low cost, and low toxicity. Objectives: This study aims to calculate physical aspects of dose enhancement of bismuth-based nanoparticles in the presence of brachytherapy source by Monte Carlo simulation and an analytical method for low mono-energy. Materials and methods: After simulation and validation brachytherapy sources (Iodine-125 and Ytterbium-169) by Monte Carlo code, bismuth-based nanoparticles (bismuth, bismuth oxide, bismuth sulfide, and bismuth ferrite) were modeled in the sizes of 50 nm and 100 nm for two concentrations of 10 and 20 mg/ml. Dose enhancement factors for the bismuth-based nanoparticles were measured at both brachytherapy sources. Furthermore, the dose amplification was calculated with an analytic method at 30 keV mono-energy. Results: Dose enhancement factor was greatest with pure bismuth nanoparticles, followed by bismuth oxide, bismuth sulfide and bismuth ferrite for both radiation source and simulation methods. The dose amplification for the bismuth-based nanoparticles increased with increasing size and concentration of nanoparticles. Conclusion: The physical aspect dose enhancement of the nanoparticles was shown by Monte Carlo and analytic method. The results have proved bismuth-based nanoparticles deserve further study as a radiosensitizer.
20
EN
The aim of this paper is to present the possibilities and purposefulness of the application of fuzzy set theory to the valuation of real options. Owing to temporal fluctuations in the market, some input parameters in a model of a real option cannot always be expressed in a precise sense. Therefore, it is natural to consider them as a fuzzy numbers. Such an approach allows us to keep more information about the possible value of real options. A hybrid (fuzzy-stochastic) model for valuing a switch option is presented. Under these assumptions, the value of a switch option will be a fuzzy random set. This article assesses the incremental benefit of product switch options in steel plant projects. Such options are valued by Monte Carlo simulation and modelling the prices of and demand for steel products using fuzzy geometric Brownian motion. Finally, the value of a product switch option is defined by the upper and lower probability distribution function.
first rewind previous Strona / 10 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.