Abstract: A solar powered air heating system using one ended evacuated tubes is experimentally investigated. A solar air heater containing forty evacuated tubes is used for heating purpose. The collector surface area is about 4.44 m2. The length and outer diameters of the outer glass tube and absorber tube are 1500, 47 and 37 mm, respectively. In this experimental setup, we have a header (heat exchanger) of square shape (190 mm x 190 mm). The length of header is 1500 mm. The header consists of a hollow pipe in the center whose diameter is 60 mm through which the air is made to flow. The experimental setup contains approximately 108 liters of water. Water is working as heat collecting medium which collects the solar heat falling on the tubes. This heat is delivered to the air flowing through the header pipe. This heat flow is due to natural convection and conduction. The outlet air temperature depends upon several factors along with air flow rate and solar radiation intensity. The study has been done for both up-flow and down-flow of air in header in similar weather conditions, at different flow rates. In the present investigations the study has been made to find the effect of intensity of solar radiations and flow rate of air on the out let temperature of the air with time and which flow is more efficient. The obtained results show that the system is highly effective for the heating in this region. Moreover, it has been observed that system is highly efficient for the particular flow rate of air. It was also observed that downflow configuration is more effective than up-flow condition at all flow rates due to lesser losses in down-flow. The results show that temperature differences of upper head and lower head, both of water and surface of pipes on the respective ends is lower in down-flow.
Abstract: In this work, the effects of scale on thermal behavior of the slab in a walking-beam type reheating furnace is studied by considering scale formation and growth in a furnace environment. Also, mathematical heat transfer model to predict the thermal radiation in a complex shaped reheating furnace with slab and skid buttons is developed with combined nongray WSGGM and blocked-off solution procedure. The model can attack the heat flux distribution within the furnace and the temperature distribution in the slab throughout the reheating furnace process by considering the heat exchange between the slab and its surroundings, including the radiant heat transfer among the slabs, the skids, the hot combustion gases and the furnace wall as well as the gas convective heat transfer in the furnace. With the introduction of the mathematical formulations validation of the present numerical model is conducted by calculating two example problems of blocked-off and nongray gas radiative heat transfer. After discussing the formation and growth of the scale on the slab surface, slab heating characteristics with scale is investigated in terms of temperature rise with time.
Abstract: The purpose of this work is to present the potential of
solar energy in Zarqa region. The solar radiation along year 2009 was
obtained from Pyranometer which measures the global radiation over
horizontal surfaces. Solar data in several different forms, over period
of 5 minutes, hour-by-hour, daily and monthly data radiation have
been presented. Briefly, the yearly global solar radiation in Zarqa is
7297.5 MJ/m2 (2027 kWh/m²) and the average annual solar radiation
per day is 20 MJ/m2 (5.5 Kwh/m2). More specifically, the average
annual solar radiation per day is 12.9 MJ/m2 (3.57 Kwh/m2) in winter
and 25 MJ/m2 (7 Kwh/m2) in summer.
Abstract: In order to enhance the aircraft survivability, the
infrared signatures emitted by hot engine parts should be determined
exactly. For its reduction it is necessary for the rear fuselage
temperature to be decreased. In this study, numerical modeling of flow
fields and heat transfer characteristics of an aircraft nozzle is
performed and its temperature distribution along each component wall
is predicted. The radiation shield is expected to reduce the skin
temperature of rear fuselage. The effect of material characteristic of
radiation shield on the heat transfer is also investigated. Through this
numerical analysis, design parameters related to the susceptibility of
aircraft are examined.
Abstract: BEAMnrc was used to calculate the spectrum and
HVL for X-ray Beam during low energy X-ray radiation using tube model: SRO 33/100 /ROT 350 Philips. The results of BEAMnrc
simulation and measurements were compared to the IPEM report
number 78 and SpekCalc software. Three energies 127, 103 and 84
Kv were used. In these simulation a tungsten anode with 1.2 mm for
Be window were used as source. HVLs were calculated from
BEAMnrc spectrum with air Kerma method for four different filters.
For BEAMnrc one billion particles were used as original particles for
all simulations. The results show that for 127 kV, there was
maximum 5.2 % difference between BEAMnrc and Measurements
and minimum was 0.7% .the maximum 9.1% difference between
BEAMnrc and IPEM and minimum was 2.3% .The maximum
difference was 3.2% between BEAMnrc and SpekCal and minimum
was 2.8%. The result show BEAMnrc was able to satisfactory predict
the quantities of Low energy Beam as well as high energy X-ray
radiation.
Abstract: So much energy is used in high rise buildings to fulfill
the basic needs of users such as lighting and thermal comfort.
Malaysia has hot and humid climate, buildings especially high rise
buildings receive unnecessary solar radiation that cause more solar
heat gain. Energy use specially electricity consumption in high rise
buildings has increased. There have been growing concerns about
energy consumption and its effect on environment. Building, energy
and the environment are important issues that the designers should
consider to them. Self protected form is one of possible ways against
the impact of solar radiation in high rise buildings. The Energy
performance of building envelopes was investigated in term of the
Overall Thermal Transfer Value (OTTV ).In this paper, the amount
of OTTV reduction was calculated through OTTV Equations to
clear the effectiveness of self shading strategy on minimizing energy
consumption for cooling interior spaces in high rise buildings which
has considerable envelope areas against solar radiation. Also increasing
the optimum window area was investigated using self-shading
strategy in designing high rise buildings. As result, the significant
reduction in OTTV was shown based on WWR.In addition slight
increase was demonstrated in WWR that can influence on visible
comfort interior spaces.
Abstract: A better understanding of cloud forest characteristic in a tropical montane cloud forest at Khao Nan, Nakhon Si Thammarat on climatic, vegetation, soil and hydrology were studied during 18-21 April 2007. The results showed that as air temperature at Sanyen cloud forest increased, the percent relative humidity decreased. The amount of solar radiation at Sanyen cloud forest had a positive association with the amount of solar radiation at Parah forest. The amount of solar radiation at Sanyen cloud forest was very low with a range of 0-19 W/m2. On the other hand, the amount of solar radiation at Parah forest was high with a range of 0-1000 W/m2. There was no difference between leaf width, leaf length, leaf thickness and leaf area with increasing in elevations. As the elevations increased, bush height and tree height decreased. There was no association between bush width and bush ratio with elevation. As the elevations increased, the percent epiphyte cover and the percent soil moisture increased but water temperature, conductivity, and dissolved oxygen decreased. The percent soil moistures and organic contents were higher at elevations above 900 m than elevations below.
Abstract: A theoretical approach to radiation damage evolution
is developed. Stable temporal behavior taking place in solids under
irradiation are examined as phenomena of self-organization in nonequilibrium
systems.
Experimental effects of temporal self-organization in solids under
irradiation are reviewed. Their essential common properties and
features are highlighted and analyzed.
Dynamical model to describe development of self-oscillation of
density of point defects under stationary irradiation is proposed. The
emphasis is the nonlinear couplings between rate of annealing and
density of defects that determine the kind and parameters of an
arising self-oscillation.
The field of parameters (defect generation rate and environment
temperature) at which self-oscillations develop is found. Bifurcation
curve and self-oscillation period near it is obtained.
Abstract: This work describes refrigeration effects during storage on total protein and amino acids composition of raw and processed flour of two pearl millet cultivars (Ashana and Dembi). The protein content of the whole raw flour was found to be 14.46 and 13.38% for Ashana and Dembi cultivars, respectively. Dehulling of the grains reduced the protein content to 13.38 and 12.67% for the cultivars, respectively. For both cultivars, the protein content of the whole and dehulled raw flour before and after cooking was slightly decreased when the flour was stored for 60 days even after refrigeration. The effect of refrigeration process in combination with the storage period, cooking or dehulling was found to be vary between amino acids and even between cultivars. Regardless of the storage period and processing method, the amino acids content was remained unchanged after refrigeration for both cultivars.
Abstract: Speckled images arise when coherent microwave,
optical, and acoustic imaging techniques are used to image an object, surface or scene. Examples of coherent imaging systems include synthetic aperture radar, laser imaging systems, imaging sonar
systems, and medical ultrasound systems. Speckle noise is a form of object or target induced noise that results when the surface of the object is Rayleigh rough compared to the wavelength of the illuminating radiation. Detection and estimation in images corrupted
by speckle noise is complicated by the nature of the noise and is not
as straightforward as detection and estimation in additive noise. In
this work, we derive stochastic models for speckle noise, with an emphasis on speckle as it arises in medical ultrasound images. The
motivation for this work is the problem of segmentation and tissue classification using ultrasound imaging. Modeling of speckle in this
context involves partially developed speckle model where an underlying Poisson point process modulates a Gram-Charlier series
of Laguerre weighted exponential functions, resulting in a doubly
stochastic filtered Poisson point process. The statistical distribution of partially developed speckle is derived in a closed canonical form.
It is observed that as the mean number of scatterers in a resolution cell is increased, the probability density function approaches an
exponential distribution. This is consistent with fully developed speckle noise as demonstrated by the Central Limit theorem.
Abstract: Pretreatment is an essential step in the conversion of
lignocellulosic biomass to fermentable sugar that used for biobutanol
production. Among pretreatment processes, microwave is considered
to improve pretreatment efficiency due to its high heating efficiency,
easy operation, and easily to combine with chemical reaction. The
main objectives of this work are to investigate the feasibility of
microwave pretreatment to enhance enzymatic hydrolysis of
corncobs and to determine the optimal conditions using response
surface methodology. Corncobs were pretreated via two-stage
pretreatment in dilute sodium hydroxide (2 %) followed by dilute
sulfuric acid 1 %. Pretreated corncobs were subjected to enzymatic
hydrolysis to produce reducing sugar. Statistical experimental design
was used to optimize pretreatment parameters including temperature,
residence time and solid-to-liquid ratio to achieve the highest amount
of glucose. The results revealed that solid-to-liquid ratio and
temperature had a significant effect on the amount of glucose.
Abstract: Iodine radionuclides in accident releases under severe
accident conditions at NPP with VVER are the most radiationimportant
with a view to population dose generation at the beginning
of the accident. To decrease radiation consequences of severe
accidents the technical solutions for severe accidents management
have been proposed in MIR.1200 project, with consideration of the
measures for suppression of volatile iodine forms generation in the
containment. Behavior dynamics of different iodine forms in the
containment under severe accident conditions has been analyzed for
the purpose of these technical solutions justification.
Abstract: In this paper, the dam-reservoir interaction is
analyzed using a finite element approach. The fluid is assumed to be
incompressible, irrotational and inviscid. The assumed boundary
conditions are that the interface of the dam and reservoir is vertical
and the bottom of reservoir is rigid and horizontal. The governing
equation for these boundary conditions is implemented in the
developed finite element code considering the horizontal and vertical
earthquake components. The weighted residual standard Galerkin
finite element technique with 8-node elements is used to discretize
the equation that produces a symmetric matrix equation for the damreservoir
system. A new boundary condition is proposed for
truncating surface of unbounded fluid domain to show the energy
dissipation in the reservoir, through radiation in the infinite upstream
direction. The Sommerfeld-s and perfect damping boundary
conditions are also implemented for a truncated boundary to compare
with the proposed far end boundary. The results are compared with
an analytical solution to demonstrate the accuracy of the proposed
formulation and other truncated boundary conditions in modeling the
hydrodynamic response of an infinite reservoir.
Abstract: In this paper, an approach for finding optimized
layouts for connecting PV units delivering maximum array output
power is suggested. The approach is based on considering the
different varying parameters of PV units that might be extracted from
a general two-diode model. These are mainly, solar irradiation,
reverse saturation currents, ideality factors, series and shunt
resistances in addition to operating temperature. The approach has
been tested on 19 possible 2×3 configurations and allowed to
determine the optimized configurations as well as examine the effects
of the different units- parameters on the maximum output power.
Thus, using this approach, standard arrays with n×m units can be
configured for maximum generated power and allows designing PV
based systems having reduced surfaces to fit specific required power,
as it is the case for solar cars and other mobile systems.
Abstract: In this study three commercial semiconductor devices
were characterized in the laboratory for computed tomography
dosimetry: one photodiode and two phototransistors. It was evaluated
four responses to the irradiation: dose linearity, energy dependence,
angular dependence and loss of sensitivity after X ray exposure. The
results showed that the three devices have proportional response with
the air kerma; the energy dependence displayed for each device
suggests that some calibration factors would be applied for each one;
the angular dependence showed a similar pattern among the three
electronic components. In respect to the fourth parameter analyzed,
one phototransistor has the highest sensitivity however it also showed
the greatest loss of sensitivity with the accumulated dose. The
photodiode was the device with the smaller sensitivity to radiation,
on the other hand, the loss of sensitivity after irradiation is negligible.
Since high accuracy is a desired feature for a dosimeter, the
photodiode can be the most suitable of the three devices for
dosimetry in tomography. The phototransistors can also be used for
CT dosimetry, however it would be necessary a correction factor due
to loss of sensitivity with accumulated dose.
Abstract: The aim of this paper is to investigate twodimensional unsteady flow of a viscous incompressible fluid about stagnation point on permeable stretching sheet in presence of time dependent free stream velocity. Fluid is considered in the influence of transverse magnetic field in the presence of radiation effect. Rosseland approximation is use to model the radiative heat transfer. Using time-dependent stream function, partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations. Numerical solutions of these equations are obtained by using Runge-Kutta Fehlberg method with the help of Newton-Raphson shooting technique. In the present work the effect of unsteadiness parameter, magnetic field parameter, radiation parameter, stretching parameter and the Prandtl number on flow and heat transfer characteristics have been discussed. Skin-friction coefficient and Nusselt number at the sheet are computed and discussed. The results reported in the paper are in good agreement with published work in literature by other researchers.
Abstract: Over the course of the past century, the global
automotive industry-s stance towards safety has evolved from one of
contempt to one nearing reverence. A suspension system that
provides safe handling and cornering capabilities can, with the help
of an efficient braking system, improve safety to a large extent. The
aim of this research is to propose a new automotive brake rotor
design and to compare it with automotive vented disk rotor. Static
structural and transient thermal analysis have been carried out on the
vented disk rotor and proposed rotor designs to evaluate and compare
their performance. Finite element analysis was employed for both
static structural and transient thermal analysis. Structural analysis
was carried out to study the stress and deformation pattern of the
rotors under extreme loads. Time varying temperature load was
applied on the rotors and the temperature distribution was analysed
considering cooling parameters (convection and radiation). This
dissertation illustrates the use of Finite Element Methods to examine
models, concluding with a comparative study of the proposed rotor
design and the conventional vented disk rotor for structural stability
and thermal efficiency.
Abstract: In electronegative-electropositive gas mixtures plasma, at a total pressure varying in the range of ten to hundred Torr, the appearance of a quasi-mochromatization effect of the emitted radiation was reported. This radiation could be the result of the generating mechanisms at molecular level, which is the case of the excimer radiation but also at atomic level. Thus, in the last case, in (Ne+1%Ar/Xe+H2) gas mixtures plasma in a dielectric barrier discharge, this effect, called M-effect, consists in the reduction of the discharge emission spectrum practice at one single, strong spectral line with λ = 585.3 nm. The present paper is concerned with the characteristics comparative investigation of the principal reaction mechanisms involved in the quasi-monochromatization effect existence in the case of the excimer radiation, respectively of the Meffect. Also, the paper points out the role of the metastable electronegative atoms in the appearance of the monochromatization – effect at atomic level.
Abstract: Medical image registration is the key technology in image guided radiation therapy (IGRT) systems. On the basis of the previous work on our IGRT prototype with a biorthogonal x-ray imaging system, we described a method focused on the 2D/2D rigid-body registration using multiresolution pyramid based mutual information in this paper. Three key steps were involved in the method ： firstly, four 2D images were obtained including two x-ray projection images and two digital reconstructed radiographies（DRRs ） as the input for the registration ； Secondly, each pair of the corresponding x-ray image and DRR image were matched using multiresolution pyramid based mutual information under the ITK registration framework ； Thirdly, we got the final couch offset through a coordinate transformation by calculating the translations acquired from the two pairs of the images. A simulation example of a parotid gland tumor case and a clinical example of an anthropomorphic head phantom were employed in the verification tests. In addition, the influence of different CT slice thickness were tested. The simulation results showed that the positioning errors were 0.068±0.070, 0.072±0.098, 0.154±0.176mm along three axes which were lateral, longitudinal and vertical. The clinical test indicated that the positioning errors of the planned isocenter were 0.066, 0.07, 2.06mm on average with a CT slice thickness of 2.5mm. It can be concluded that our method with its verified accuracy and robustness can be effectively used in IGRT systems for patient setup.
Abstract: Dynamics of laser radiation – metal target interaction
in water at 1064 nm by applying Mach-Zehnder interference
technique was studied. The mechanism of generating the well
developed regime of evaporation of a metal surface and a spherical
shock wave in water is proposed. Critical intensities of the NIR for
the well developed evaporation of silver and gold targets were
determined. Dynamics of shock waves was investigated for earlier
(dozens) and later (hundreds) nanoseconds of time. Transparent
expanding plasma-vapor-compressed water object was visualized and
measured. The thickness of compressed layer of water and pressures
behind the front of a shock wave for later time delays were obtained
from the optical treatment of interferograms.