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Abstract: The dynamics of reformation and replacement of gas hydrates were studied under nonequilibrium conditions. It was found that the reformation of gas hydrates is largely affected by the state of the gas‐water system and the restarting temperature. This suggests that the effects are caused by changes in the structure of the aqueous solution at a molecular level. Pure samples of CH4 gas hydrate were synthesized from ice crystals and the dissociated solution using the reformation method. Replacement of CO2 gas hydrate is achieved within a short duration in the solid‐phase sample of CH4 gas hydrate, if the pressure and temperature is precisely controlled in a pressure vessel.

Abstract The commonly used transmutation rate of minor actinides in nuclear reactors is decomposed into four components, overall fission rate, Pu production rate, MA production rate, and element production rate. The physical meanings of these factors are described. The transmutation rates of minor actinides in two types of highly-moderated PWRs, a MOX fueled Na cooled fast reactor, and a metal fueled Pb cooled fast reactor are interpreted using the four components. The metal fueled Pb cooled fast reactor can incinerate minor actinides most (79kg/GWth/year), and this amount is about 4 times larger than the thermal reactors. The thermal reactors have large relative overall fission rates for 241 Am and have a potential for the incineration of 241 Am.

We investigate the driving behavior differences at unsignalized intersections between expert and nonexpert drivers. By analyzing real-world driving data, significant differences were seen in pedal operations but not in steering operations. Easing accelerator behaviors before entering unsignalized intersections were especially seen more often in expert driving. We propose two prediction models for driving behaviors in terms of traffic conditions and driver types: one is based on multiple linear regression analysis, which predicts whether the driver will steer, ease up on the accelerator, or brake. The second predicts driver decelerating intentions using a Bayesian Network. The proposed models could predict the three driving actions with over 70% accuracy, and about 50% of decelerating intentions were predicted before entering unsignalized intersections.

Biodiesel fuel is a fatty acid alkyl ester, commonly synthesized via transesterification of triglycerides (vegetable oils and animal fats) with an alcohol, in a presence of a catalyst. Production of biodiesel fuel from waste vegetable oil eliminates additional costs of growing oilseed plants as a raw material, reduces the amount of waste in the food sector, preserves fertile land area and water, eliminates direct competition with food which could otherwise potentially lead to price increase and shortages of edible vegetable oils. The structure of the biodiesel molecule depends on the feedstock from which it's synthesized. The triglyceride’s fatty acids have mainly straight hydrocarbon chains, so the alcohol molecule determines if the ester will be straight-chained or branched. The molecule structure is determinant for some diesel fuel properties. For example, longer straight-chained molecules will have higher cetane number values, while branched ones will have lower pour point values and, therefore, engines will be able to perform at lower temperatures. Cetane number is the prime indicator of the fuel quality used in the internal combustion compression engines. Some biodiesel fuels show high cetane number values. It has been proven that longer hydrocarbon chains in the ester molecules are proportionately related to the cetane number value, therefore, synthesis with higher alcohols are being tested, such as 1-Hexanol. In this research, the influence of reaction parameters on the transesterification process of waste vegetable oil with 1-Hexanol was examined. The influence of the alcohol/oil molar ratio, the influence of the mass fraction of the alkaline catalyst KOH, the influence of the reaction time and temperature were monitored. The conversion was calculated from 1H NMR spectra by integrating the surface areas of specific signals. The experimental part of the research established that 60 °C is the best temperature out of given three in the reaction. 12:1 alcohol to oil molar ratio had a higher conversion because greater excess of an alcohol shifted this reversible chemical reaction more towards the products. The catalyst mass fraction of w(KOH) = 3 % gave higher reaction yields than the 1 % one. High conversions of the reaction were obtained after only 2 minutes, but by the 15th minute the conversion increased by approximately 1.59 % and reached its near maximum. It was experimentally shown that the parameters that have the greatest effect on conversion are the mass fraction of the catalyst and the alcohol to oil molar ratio. Biodizel je ester masnih kiselina koji se najčešće sintetizira reakcijom transesterifikacije triglicerida (biljna ulja i životinjske masti) s alkoholom u prisustvu katalizatora. Proizvodnjom od otpadnog ulja, eliminiraju se dodatni troškovi uzgoja biljaka uljarica, štede se plodne površine i voda, izbjegava se kompeticija s hranom što može dovesti do rasta cijena i nedostatka hrane (jestiva biljna ulja) te se smanjuje nastanak otpada u prehrambenom sektoru. Struktura molekule biodizela ovisi o sirovinama od kojih se sintetizira. Masne kiseline triglicerida uglavnom su ravnolančane, stoga molekula alkohola određuje hoće li ester biti razgranat ili ravnolančan. Oblik molekule je odlučujuć za neka svojstva dizelskog goriva. Primjerice, duže ravnolančane molekule povećat će vrijednost cetanskog broja, dok će razgranati esteri sniziti tecište što će omogućiti rad pri nižim temperaturama. Cetanski broj je primarni indikator kvalitete goriva korištenog u kompresijskim motorima s unutarnjim izgaranjem. Neki biodizeli pokazuju visoke vrijednost cetanskog broja, no dokazano je kako su dulji ugljikovodični lanci u molekulama estera proporcionalno povezani s vrijednosti cetanskog broja. U tu svrhu istražuju se sinteze s višim alkoholima poput 1-heksanola. U ovom radu ispitivani su utjecaji reakcijskih parametara na iskorištenje reakcije transesterifikacije otpadnog ulja s heksanolom. Pratio se utjecaj molarnog omjera alkohol/ulje, utjecaj masenog udjela lužnatog katalizatora KOH, utjecaj reakcijskog vremena i temperature. Iskorištenje se određivalo iz 1H NMR spektra integriranjem površine pojedinih signala. Eksperimentalnim dijelom rada utvrđeno je da se najveće iskorištenje dobiva pri temperaturi od 60 °C. Veće iskorištenje reakcija je imala s molarnim omjerom alkohol/ulje 12:1. Veći suvišak alkohola ovu je ravnotežnu reakciju pomaknuo više prema produktima. Maseni udio katalizatora od w(KOH) = 3 % dao je veća iskorištenja reakcije u odnosu na w(KOH) = 1 %. Visoka iskorištenja reakcije dobila su se već nakon 2 minute, no do 15. minute iskorištenje se u prosjeku još povisilo za 1,59 % i doseglo svoj maksimum. Eksperimentalno je pokazano da na iskorištenje najviše utječu parametri maseni udio katalizatora te molarni omjer alkohol/ulje.

Real-time pricing demand response programs (RTP-DRPs) are practical measures that ensure the end user's profitability from using electricity by adjusting the supply and demand equilibrium without activating costly solutions. This study explores the potential of RTP-DRPs by developing and applying a region-wise modeling approach based on maximizing the end user's social welfare in the wholesale electricity market in Japan. The regions of the wholesale market are classified based on their response into regions with excess supply, regions with high demand burden, and regular suppliers of inter-regional connections. The results revealed that the RTP-DRPs could potentially reduce the peak demand of the residential sector in Chubu, Chugoku, Kansai, Kyushu, Tokyo, and Tohoku by 1.91%-7.81%. Meanwhile, in Hokkaido, Hokuriku, and Shikoku, by 16.13%-22.9%. The avoided greenhouse emission (GHG) in Tokyo is estimated to be 82.6 and 192.2 tons in summer and winter, respectively.

Driven magnetic reconnection in a collisionless plasma is investigated by means of a two-and-one-half dimensional particle simulation. The dynamical compression by plasma inflow forms a peaked profile of current density in the neutral sheet. When the width of current layer is compressed as thin as the ion Larmor radius, the charge separation becomes distinct abruptly at the center bf the current layer due to the finite ion Larmor radius effect. The charge separation in the central current region and the subsequent spatial modification of the current profile result in excitation of collisionless driven magnetic reconnection. In the cause of collisionless driven magnetic reconnection an efficient energy conversion from field energy to particle energy is observed.

Analytical and experimental studies of a brushless, exciterless, single-phase, sinusoidal-wave synchronous machine operating as a generator or a motor, derived from a three-phase machine, are reported. One phase armature winding of the three-phase machine is used as an auxiliary stator winding of the single-phase machine and is used to supply the exciting power for the other two-phase armature windings acting as the load winding of the single-phase machine. A 1.5 kW, 200 V, 60 Hz, four-pole synchronous machine was used the experiments. It is shown that the waveforms of the armature terminal voltage and the load current are nearly sinusoidal. The advantages of the single-phase machine as a portable generator or small-load motor are discussed. >

Abstract This study demonstrates the possibility to use energy-cost optimal building designs based on life cycle approach. There is a lack of studies that cover the comprehensive assessment of both embodied energy (EE) and operational energy (OE) in a single optimization problem. The primary goal of the current study is to compare the optimized results of using OE+EE together and OE only. The optimization is performed on a case study building (townhouse) in Finland with three structural alternatives (i.e., reinforced concrete (RC); cross-laminated timber (CLT) and Steel). Different options for insulation thickness of external wall, roof, floor and window types were considered as decision variables as the scope of the present study is on building envelope. The objectives of the optimization are to minimize life cycle energy (LCE) and life cycle costs (LCC). The LCE difference between the most and least energy efficient solution on the pareto front is greater in case of the OE optimization, compared to OE+EE optimization. For all studied structures, the EE of the optimal solutions from OE+EE optimization ranges 16%–23% of LCE. Many of the non-dominated optimal solutions obtained from the OE+EE optimization shows a higher U-value for the building envelope components compared to the optimal solutions from the OE optimization. A relationship between both OE and EE with the overall thermal resistance of the building envelope is discussed to obtain a deeper understanding of such differences in U-value for the optimal solutions obtained from the OE+EE and OE optimization.

U radu je opisan princip rada kogeneracijskih postrojenja te neke dostupne tehnologije koje koriste krutu biomasu kao gorivo. Naglasak je stavljen na vodeno-parno postrojenje te na postrojenje koje koristi organsku radnu tvar, tzv. ORC postrojenje. Također, izrađeni su pojednostavljeni matematički modeli dinamike procesa za termouljni i vodeno-parni kotao s izgaranjem biomase na rešetki kako bi bilo moguće simulirati utjecaj vlažnosti biomase na parametre na izlazu iz kotla. Proveden je termodinamički proračun izgaranja te dimenzioniranje veličina u sustavu. Početni podatak bio je potreban toplinski tok koji se mora prenijeti na radni medij koji iznosi 5MW. Nakon toga uslijedila je simulacija utjecaja promjenjive vlažnosti na temperature na izlazu iz izmjenjivača te su tablično prikazani dobiveni podaci. Na kraju su opisani problemi koje prevelika ili premala količina vlage u biomasi može izazvati u postrojenjima te regulacijske mjere koje mogu taj učinak kompenzirati. This work describes the general principles of some commercially available cogeneration technologies that use solid biomass as a fuel. Emphasis is placed upon water-steam and ORC cogeneration plants. Also, simplified mathematical models of sintetic oil and water-steam boilers with combustion of solid biomass on a grid were made in order to simulate the impact of biomass moisture on working fluid exit temperatures. The thermodynamic calculation of boiler was made and plant dimensions were chosen. Initial data was the required heat flow that needs to be transferred between flue gases and working fluid with a value of 5MW. After that the simulation of variable moisture impact on working fluid exit temperatures was made and the results are shown in pictures. At the end, some problems that occur from variable moisture in plants were described and some regulatory measures proposed.