In the present study the performance of drying process of dffirent solid materials by batch fluidized bed drying
under vacuum conditions was investigated. Three, different solid materials, namely; ion exchange resin-8528,
aspirin and paracetamol were used. The behavior of the drying curves as well as the rate of drying of these
materials had been studied. The experiments were caried out in a 0.0381 m column diameter fluidized by hot
air under yacuum conditions. Four variables affecting on the rate of drying were studied' these variables are
vacuum pressure (100 - 500 mm Hg), air temperature (303-323 K), particle size (0.3-0.8 mm) and initial
moisture content (0.35-0.55 g/g solid)-for resin and (0.1-0.2 g/g soltid) for aspirin and paracetamol. The study of
the characteristics of the drying curves showed that the drying behavior depends mainly on the type of the solid
material and on the operating conditions. It was found that the drying rate at vacuum conditions is enhanced by
increasing the operating temperature of the air and decreases by increasing the initial moisture content of the
material and the particle size. Moreover, an experiment was carried out to study the drying of aspirin solid
material which is dried in atmospheric fluidized bed dryer operating at the same conditions to compare the
temperature and time needed in both techniques. It was found that the temperature needed for vacuum fluidized
bed dryer (303 K) is less than needed by fluidized bed dryer operating at atmospheric pressure (323 K). A
simpliled model'for the drying of solids in the constant-rate period in a batch fluidized bed is developed,
considering the bed to consist of dense phase and bubble phase with heat and mass transfer between the phases.
It is assumed that the solids in dense phase to be in thermal equilibrium with the interstitial gas in the dense
phase. The bubble size, its rise velocity, and the bubble volume fraction are taken into account while developing
the model. The model is compared with experimental data reported in this study and found to match
satisfactorily.
Background: Ejection fraction have been used frequently
for assessment of the left ventricular function, but can be
associated with errors in which myocardial performance
index have been used as another parameter to measure the
left ventricular function.
Objective: selecting another echocardiography parameter
for the assessment of myocardial in function instead of the
ejection fraction.
Methods: 160 patients referred to the echocardiogram unit
from the period december 2007 to august 2008 requesting
assessment of left ventricular function. After clinical
examination, routine blood tests; chest x-ray and
electrocardiographic recording have been completed. All
patients informed to come for this unit af
Chitosan (CH) / Poly (1-vinylpyrrolidone-co-vinyl acetate) (PVP-co-VAc) blend (1:1) and nanocomposites reinforced with CaCO3 nanoparticles were prepared by solution casting method. FTIR analysis, tensile strength, Elongation, Young modulus, Thermal conductivity, water absorption and Antibacterial properties were studied for blend and nanocomposites. The tensile results show that the tensile strength and Young’s modulus of the nanocomposites were enhanced compared with polymer blend [CH/(PVP-co-VAc)] film. The mechanical properties of the polymer blend were improved by the addition of CaCO3 with significant increases in Young’s modulus (from 1787 MPa to ~7238 MPa) and tensile strength (from 47.87 MPa to 79.75 MPa). Strong interfacial
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This work presents a simple method for determination of the neutron reflection coefficient (n) as a function of different neutron reflector materials.A laboratory neutron source (Am-Be) with activity of 16 ci is employed with a (BF3) neutron detector. Am-BeThree types of reflector materials are used as samples, the thickness of each sample is (5cm).It is found that( ?7) is: -For polyethlyene = 0.818
In this research, that been focused on the most important economic benefits expected when applying the three standards of sustainability in construction projects (economic, environmental and social). Fuzzy AHP, a multi-decision decision-making technique for evaluating construction projects. Which when used we get the speed and accuracy in the results. Using this technique will reduce uncertainties decisions significantly (fuzzy environment), that found in most projects .The results of the data analysis showed that the economic standards take the greatest relative importance (60%) among the three sustainability standards. Therefore, the implementation of any standards need a cost so the economic benefit of any proje
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The nonlinear refractive (NLR) index and third order susceptibility (X3) of carbon quantum dots (CQDs) have been studied using two laser wavelengths (473 and 532 nm). The z-scan technique was used to examine the nonlinearity. Results showed that all concentrations have negative NLR indices in the order of 10−10 cm2/W at two laser wavelengths. Moreover, the nonlinearity of CQDs was improved by increasing the concentration of CQDs. The highest value of third order susceptibility was found to be 3.32*10−8 (esu) for CQDs with a concentration of 70 mA at 473 nm wavelength.
This work deals with determination of optimum conditions of direct diffusion bonding welding of austenitic stainlesssteel type AISI 304L with Oxygen Free High Conductivity (OFHC) pure copper grade (C10200) in vacuum atmosphere of (1.5 *10-5 mbr.). Mini tab (response surface) was applied for optimizing the influence of diffusion bonding parameters (temperature, time and applied load) on the bonding joints characteristics and the empirical relationship was evaluated which represents the effect of each parameter of the process. The yield strength of diffusion bonded joint was equal to 153 MPa and the efficiency of joint was equal to 66.5% as compared with hard drawn copper. The diffusion zone reveals high microhardness than coppe
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