The most significant application of refrigeration is in food preservation, weather it is by way of processing or for cold storage. The preservation of food is defined as the preservation of palatability and nutritive value of food preventing the natural spoilage with respect to time. Solar refrigeration is thought as one of the best techniques to address this issue, due to its good match to the variation of solar radiation; namely, the supply of sunshine, and the cooling output of a solar refrigeration system reach maximum levels at the same season. The thermoelectric refrigeration system (TEC), which has the merits of being light, reliable, noiseless, rugged, and low cost in mass production, uses electrons rather than refrigerant as a heat carrier, and is feasible for outdoor purposes in cooperation with solar photovoltaic (PV) cells, in spite of the fact that its coefficient of performance is not as high as for a vapor compression cycle . The theory of combined solar thermoelectric refrigerator is proposed and for its optimum operation, the ratio of number of thermocouples required is given by Vella et al. . After that, a small prototype of thermoelectric refrigerator powered by solar photovoltaic solar collectors was proposed by Sofrata . A theoretical model of thermoelectric device has been
ABSTRACT Malaysia needs to produce affordable quality homes to house the country’s growing population and meets demands arising from migration of people to economic centres in the urban areas. The country is therefore looking for suitable alternatives to conventional building systems to provide affordable quality housing to its citizens. As a part of this effort, the civil engineering department at the Universiti Putra Malaysia, has undertaken extensive experimental and theoreticalinvestigations to develop a load bearing system using Precast Concrete Sandwich Panel (PCSP). A description of these investigations is presented in this paper. The paper also concludes with some major results and a discussion of further research is provided.
Theoretical calculations that em ploy periodic boundary conditions are an effective w ay to model the physical properties of solid materials at the atom ic level as a com plem ent to the experimental studies . In this respects, we performed our calculations using a self-consistent schem e by solving the Kohn- Sham equations using density functional theory (DFT) along with local density approximations (LDA), generalized gradient approximations (GGA)  and Modified Becke-Johnson method (m BJ-GGA) as implemented into WIEN2k p a c k a g e .
The other form of difference imaging is where the object being imaged itself is used as the reference phantom. Image data are acquired before and after a change in optical properties within an object that almost invariably has heterogeneous optical properties. This change may be invoked, be a deterioration or change over time, or be the difference in measurement at multiple wavelengths. However the resulting image reconstructions from such difference data can be incorrect. The problems are a direct result of the inherent non-linearity of optical tomographic image reconstruction. This chapter describes the perturbation approximations intrinsic in both linear and non-linear image reconstruction schemes. We then explore how these assumptions affect images of changes in absorption in the presence of a) heterogeneous background scatter, and b) heterogeneous background absorption using simulations. Comparisons of results using non-linear (TOAST) and linear image reconstruction techniques (see section 220.127.116.11), along with experimental studies are included throughout. The origin and dependence of the error are then investigated. We then present a method found to improve results which uses estimates of background structure from baseline images. This is shown to improve quantitation and object localisation in simple images. The significance of this error is discussed in context with similar studies and in relation to successful, reliable clinical imaging as well as implications for other forms of NIR spectroscopy.
in ‘line-diode’ circuits in the case of partial reflection . A delay nonlinear differential equation has been proposed in  to study the possible generation of chaos in the front-end microwave limiter receivers. In this paper, we present theoretical and experimentalinvestigations of chaos generation in the front-end receivers for different types of antenna, 2.45 GHz resonant frequency antennas (patch, monopole and loop antennas) and 8.2–12.4 GHz bandwidth horn antenna. For each antenna, theoretical and experimental bifurcation diagrams derived from delay nonlinear differential equation proposed in  are exploited to show the existence of the chaos. To the author knowledge, it is the first work which demonstrates the experimental chaos generation in the front-end receivers.
geometrical parameters and vibrational assignments of 4B3MBN for the ground state had been deliberated through the theoretical methods invoking a basis set. The charges are computed by MA with same basic sets tabulated. The visual representations are the mostly welcomed one compared with other studies. Finally, spectra of the title compound have good complement while compared with the calculation results were applied to simulate infrared and Raman spectra.
The experimental characteristic curves for the four impellers with inlet blade angles of 90˚, 115˚, 125˚ and 135˚ are shown in Figure 7. It can be observed that, the compression increases as the losses behind the blades de- creases. This leads to the improvement of the regenerative blower performance and efficiency. So the impeller of inlet blade angle of 125˚ has a better efficiency than the other impellers with inlet flow angles (90˚, 115˚ and 135˚). The efficiency is generally low at lower flow rates and it increases as the flow rate through the blower in- creases . This is another characteristic of the regenerative blower, which suggests that in order to obtain a good efficiency; the blower should be operated at a higher flow rate. The reason for low efficiency at a low flow rate is due to greater circulatory power, the increased number of circulations at the low flow rates, causes the in- crease of both circulatory head loss and shock loss. When the flow rate increases through the blower, there will be fewer vortices circulations, which mean better efficiency . The change of inlet blade angles leads to redi- rection of the inlet flow to the impeller, which leads to the increase of the transferred energy from impeller blade to the flow inside the channel and leads in turn to the improvement of the blower performance and efficiency. Figure 8 shows the relation between the inlet blade angle and maximum efficiencies at the maximum flow rate (at dimensionless flow coefficient of 0.7). The maximum efficiencies were found to be 47.72, 45.59, 44.69, and 43.59 % for impellers of inlet blades angles 125˚, 135˚, 90˚, and 115˚ respectively.
For better understanding of molecular arrangements in liquids results of theoretical evaluation of ultrasonic velocities are used. Ultrasonic study of liquid and liquid mixtures has been gained much importance during the last two decades in assessing the nature of molecular interactions and investigating the physicochemical behaviour of such systems. Several researchers [1-5] carried out ultrasonic investigations on liquid mixtures and correlated the experimental results of ultrasonic velocity with theoretical relations of Nomoto , Van dael and Vangeel , impedence relation , Rao’s specific velocity  and Junjie  and the results are interpreted in terms of molecular interactions. Velocities in three binary liquid mixtures of quinoline with o-cresol, m-cresol and p-cresol using the above theoretical relations are compared with the experimental values of ultrasonic velocities at four temperatures 303.15, 308.15, 313.15 and 318.15 K. An attempt has been made to study the molecular interaction from the deviation in the values of U 2 exp /U
Theoretical and experimentalinvestigations of the natural convection heat transfer from a plane wall to a thermally stratified environment have been carried out in the present work to show the the significant effect of natural convection in a stratified media on the temperature profile, velocity profile and local Nusselt number. The results can be summarized as follows: 1.) For constant heat flux, Stratification parameter has the marginalized effect on the temperature, velocity profiles and local Nusselt number. 2.) The effect of stratification parameter is marginalized with the increase in Prandtl number. 3.) Thermal boundary layer was approximately independent on downstream coordinates. 4.) The reversal of temperature is strong at high Prandtl numbers and weaker at low numbers and the reversal of flow velocity is strong at low Prandtl numbers and weaker at high numbers. 5.) The increase in Grashof number does not practically vary the effect of stratification on temperature and velocity profiles. 6. ) As Prandtl number increases the Nusselt number first decrease, then increase. Comparison was made between present experimental and theoretical temperature profile and local Nusselt number. The temperature profile and local Nusselt number follows the same behavior with a mean difference of 7.75% for temperature profile and 20% for local Nusselt number. The present experimental and theoretical results also have been compared with the available previous studies for temperature profile, velocity profile and local Nusselt number, and give a good agreement.
The Interfacial activity of Vitex doniana (VD) leaves extract as inhibitor has been studied on carbon steel corrosion in hydrochloric acid solution using weight loss, gasometry, electrochemical techniques and quantum chemical calculations. Increase in inhibition efficiency with increased inhibitor concentration which indicate that VD molecules acted by accumulating at metal/electrolyte interface. Weight loss results show that inhibition efficiency increased with increase in inhibitor concentration but decreased with increase in temperature indicating a physical adsorption. Data obtained from the potentiodynamic polarization scan revealed that the corrosion inhibitor shifted corrosion potentials to more negative potential indicating prominent cathodic protection. The impedance data showed a decrease in double layer capacitance and an increase in charge transfer resistance which suggests that electron migration was retarded in the bulk solution. The Nyquist and Bode plots of the test solutions were similar in both inhibited and free medium but contained capacitive and inductive loops. To assess the interaction of VD molecules with Fe(110) surface, quantum chemical calculations were performed to elucidate the molecular reactivity parameters of inhibitor molecules while molecular dynamics studied the binding properties of inhibitor molecules on metal surface. Local reactivity was estimated and discussed through condensed Fukui indices. Theoretical calculations were carried out using Dmol3 basis set for all atoms.
Ultrasonic study of liquids and liquid mixtures has gained much importance in assessing the nature of molecular interactions and also helpful in investigating the physico-chemical behavior of such system. The increasing use of THF, DIOX, aromatic ethers and aromatic amines in many industrial processes created theoretical interest in understanding the nature of associated solutions. These studies have greatly stimulated the need for extensive information on properties of mixtures involving these components. Different volumetric and thermal effects are observed upon mixing because of the molecular interactions between ethers + amine [1–3]. The formation of hydrogen bonds is suggested between primary amino and secondary imino groups with weak proton donor ability and the unshared electron pairs on the oxygen atom of ether. Several researchers [4–8] carried out ultrasonic investigations on liquid mixtures and correlated the experimental results of ultrasonic velocities with the theoretical relations of Nomoto , Van Dael and Vanjeel , Impedance relation , Junjie , Kudriavtsev relation  and interpreted the results in terms of molecular interaction. Since these acoustic parameters provide better insight into molecular environments in liquid mixtures, it seemed important to study molecular interactions in terms of these parameters in binary mixtures. In the present paper, we report the measured values of ultrasonic velocities and densities of four binary liquid mixtures of Benzylamine with tetrahydrofuran, 1,4-dioxane, anisole and diphenylether and various theoretical relations are compared with the experimental values of ultrasonic velocities at 303.15 K.
Vibration isolation is of great importance in a lot of fields. Especially for high precision systems, it is desired that unwanted vibration will be isolated so that they have no influence on the performance of the system and high precision can be maintained. Vibration isolators are systems that are capable of isolating these unwanted vibrations. There are a wide variety of isolators available, which are based of different principles. This research will focus on a new possible way to isolate vibrations, namely by using a magnetic levitation system. The majority of the research is about analyzing the theoretical dynamics of such a system in order to gain more understanding in its frequency dependent behaviour and vibration isolation characteristics. Additionally, some research about magnetic forces and a part of the experimental analysis is done.
To test the theoretical predictions, the magnetization was computed by performing zero tem perature Monte Carlo simulations. This is a simple variant on the method described in section 2.1.2. In this case only spin moves which lower the energy are accepted . In Fig. 3.9 these estimates are plotted versus the anisotropy D / J and compared with the small anisotropy result (Eqn. (3.13)) and the large anisotropy result (Eqn. (3.24)). The agreement is seen to be excellent in both cases, with each asymptotic equation breaking down near the tricritical point at Dtc/J = 5. It is therefore tem pting to associate the change in order of the transition with a non-linear cross over from a regime th at is nearly ferromagnetic, to one th at is nearly q = 0 spin ice.
core-cladding radius and q for the cladding at = 780 nm is 1.4967, the index of refraction of the cladding is 1.5002. 5 Therefore, we calculate i to be 126 m. Experimentally, we nd i to be 108 m from the center of the core, or an Fabry-Perot cavity size of 45 m . This was measured by placing the ber directly on the measured surface, establishing a zero distance, and then adjusting the distance separation such that the amplitude of the interference fringe was maximized. During this measurement, the ber was placed on a translation/goniometer stage controlled by micrometer actuation. Fine control and active feedback on the interferometer position (vide infra) of the positioning was accomplished by incorporation of a piezeoelectric actuator. The goniometer served the purpose of adjusting the angle of the face of the cleaved ber face with the surface of the mechanical oscillator. It should be noted that this experimental measurement is subject to some error in estab- lishing the correct zero, due to monitoring the ber being ush with the surface by eye. Furthermore, during the polishing process, it is possible the surface roughness at both the cleaved end and the exit end of the ber are causing aberrations in the lens. It is suggested that after the polishing the ber is sonicated in Syton ° R HT-50, a colloidal suspension of