Papers by Keyword: Entropy

Abstract: In this work, we consider is the single-particle bound-state problem. A single-particle moves in the absence of the anharmonics oscillator asymmetric potential. The bound-state problem then is to solve the partition function for single-particle in the presence of anharmonics oscillator asymmetric potential. The factor second exponential function of partition function of particle bound in the anharmonics oscillator asymmetric potential can also be expanded in power series of the temperature and parameter , , and is the position of single-particle bound-state problem and using the integrate Gaussian. The purpose of this works, we will compute the partition function as a function of temperature, entropy, specific heat capacity and standard deviation which depend on the parameter and frequency.

Abstract: In this research, a fundamental quantum mechanics and statistical mechanic bound-state problem of harmonics oscillator cosine asymmetric was considered by using partition function method. From the study, it found that the internal energy, the entropy and the specific heat capacity of particle vibration bound-state under harmonics oscillator cosine asymmetric potential were increased as the increasing of the parameters of μ, η, and β. While an increasing of parameter α affected to the decreasing of the entropy and the heat capacity. In addition, the increasing values of the entropy and the specific heat capacity value were depended on the decreasing of the parameter α value.

Abstract: Interdiffusion in two-phase Ni-Cr-Al diffusion couple was studied experimentally and simulated numerically. The diffusion multiples were prepared by hot isostatic pressing, HIP and post-annealing at 1200°C. The concentration profiles were measured with wide line EDS technique – a method suitable to study multiphases. Hence the diffusion paths were determined. The experimental profiles and diffusion paths were compared with numerical results simulated with application of the Darken bi-velocity method implemented to describe interdiffusion in a two-phase zone.

Abstract: Biodeterioration of lignocellulosic materials is a worldwide problem and it causes a great damage especially to unique manuscripts and books stored in libraries. These materials are permanently subject to suffering from physical, chemical, and/or biological changes. Biological deterioration by microorganisms (bacteria and fungi) causes undesirable changes on material properties. Paper made by vegetal fibers, functional additives (glue, optical polishers, consolidating nts), and inks with organic bindings are used as sources of nutrients. Using of EOs (essential oils) for protection against microorganisms appears to be an option, because antimicrobial effects of the main compounds of EOs were proven. This work analyzes the antimicrobial stability of 2 essential oils (citral and linalyl acetate), as well as their stability of mechanical properties, in selected lignocellulosic materials (soft wood and hard wood kraft pulp, softwood sulphite pulp). Some parts of samples were subjected only to the condition of the EOs, other samples were firstly treated by accelerated ageing. Last samples were exposed to the accelerated ageing and afterwards treated by EOs. From the mechanical properties measuring of samples it is possible to state that in some SAJ samples the influence of EOs vapour is positive. This was monitored even when the samples were treated by accelerated ageing.

Abstract: The recent vehicle management systems have been developing to improve the quality of the combustion process and transmission systems. In thermodynamic approach, the water molecule can exists in different phases like ice, water, wet steam, dry steam, and superheated steam. The phase change occurs in the steam formation process can be compared to the various stages of any vehicle dynamic system such starting, idling, normal speed, high speed and very high speed. There may be an identical value in the increment of energy level in both steam formation process and any vehicle dynamic system. Thermodynamic approach always deals with system, surroundings, boundary and energy transformation across boundaries. Entropy is a very good property which is used to find the energy degradation in a particular system, and this property existence in the vehicle dynamics of automobiles will be used to improve the efficiency of the control module of a vehicle management system. This paper initiates a new angle research in the field of vehicle dynamics to study and investigate the kinetic energy transformation and distance moved by the vehicle thermodynamically. From this paper, Entropy is found as a very good property for increasing the mileage of the vehicle. In the vehicle health monitoring, there should be an entropy measurement to reduce the unavailability of energy as it is the measure of the distance travelled by the vehicle per unit energy supplied to the same vehicle at various operating speeds. In manual transmission method, it has been found that driver is not able to press the accelerator pedal continuously due to body strain. Driver has to run the vehicle at constant speed by pressing the accelerator pedal continuously. In automatic transmission, the data required for the ECU module is given by the thermodynamic relations such as enthalpy, entropy and internal energy. This paper aims thermodynamically to describe the speed, acceleration, fuel consumption, kinetic energy and various resistances offered to the vehicles. Generally, Thermodynamic system deals with heat and mass transfer, likewise vehicle dynamics deals with work and vehicle’s motion.

Abstract: This paper proposes the evaluation of material coefficient of heat dissipation rate for building materials, in particular using partial entropies, a temporal change in entropy upon heating a sample of a studied material and a temporal change in entropy upon overheating a sample of a studied material, in order to evaluate the rate of heat dissipation on samples of building materials with thermal insulating properties. From a physical point of view, the material parameter “specific heat capacity” generally refers to the ability of material to “conceive heat” so it can be said that the illustrated material Ytong has a slightly higher specific heat capacity than that of polyurethane. From a physical point of view, the material parameter “thermal conductivity” generally refers to the ability of a given material to “conduct heat through the material in connection with stationary heat flux”, so it can be assumed as well as verified by measuring that Ytong also has a higher thermal conductivity than that of polyurethane. From a physical point of view, the newly proposed material parameter “heat dissipation rate” generally indicates the “rate of heat loss to the external environment in connection with non-stationary heat flux”, so it may also be assumed and verified by measuring that the heat dissipation rate of Ytong will be higher than that of polyurethane.

Abstract: Two samples of industrial alloys on the basis of copper are experimentally studied. These alloys are used for production of amorphous solders. The main studied property is kinematic viscosity of metal melt in a liquid state. Data of viscosity dependences from temperature when heating and the subsequent cooling are obtained. Besides, viscosity dependences at constant temperatures from time are received. On viscosity dependences from temperature, for the same samples, abnormal sites and a divergence of curves of heating and cooling are found. On viscosity dependences from time, at a constant temperature, instability is found. The conclusion is drawn that the revealed features are connected with complexity of relaxation process of the studied fusions.

Abstract: A study of crystalline structure, magnetic and magnetocaloric properties of Dy(Co_1-хFe_х)₂ (х = 0.10, 0.15) intermetallic compounds was undertaken. Phase composition was controlled by X-ray diffraction analysis. Magnetic properties were measured with a help of SQUID magnetometer in magnetic fields up to 7 Т in the temperature range from 4.2 K to 400 K. Magnetic transition temperatures from paramagnetic to magnetically ordered state were inferred as 288 K and 350 K, respectively. It is shown that at an increase of iron concentration and/or magnetic field intensity, a considerable maximum broadenings on a temperature dependence of magnetic entropy change is observed. The calculated value of the relative cooling power (RCP) of Dy(Co_0.90Fe_0.10)₂, in a magnetic field of 1.7 T is equal to 152 J/kg that is close to that for Gd metal with RCP = 181 J/kg at μ₀Н = 2 T.

Abstract: The entropy generation of any thermodynamic system provides a useful measure of extent of irreversibility. The irreversibility causes the loss of useful work (exergy) in the system and it has to be minimized. Thermal radiation, coming from the sun is rich in exergy. Entropy generation is one of the parameter that quantifies the loss of exergy. It is a unique parameter to measure the strength of irreversibility of thermodynamic process. The criterion for the optimal thermodynamic operation of a collector is used in terms of Entropy Generation Number (N_s) and Mass Flow Number (M). In this paper, the performance of a 10 W_p photovoltaic thermal (PVT) system is analyzed. The range of mass flow rates to be used for testing is obtained by entropy minimization method. The maximum electrical, thermal and exergy efficiency of 10.9, 23.5, 14.8 % is obtained at the mass flow rate of 0.008 kg/s.

Abstract: Expertise or certain performance metrics information was often separately considered to model the Aircraft baseline scenario preferential problem in a traditional way, with one-sidedness and subjective. This paper focus on baseline scenario preferential problem in aircraft conceptual design, proposed a hybrid fuzzy decision merit model with synthesizing the description and numerical fuzzy indicators and using interval theory to model the fuzziness of each attribute. Proposed the preference information method based on multi-level expertise interval scale to model description fuzzy indicators and grey incidence analysis to model numerical fuzzy indicators, induced objective information entropy to increase the discrimination degree among group information, and then established a hybrid fuzzy interval multi-attribute decision model based on expertise, grey scale and objective information entropy, by constructing the Lagrangian function to solve each attribute weights. Applied it to the aircraft baseline scenario preferred example, to verify its feasibility and effectiveness.