انتقال الحرارة بين سطح عمودي لمبادل حراري وحبيبات صلبة ساقطة على طول ارتفاعه
This paper presents a theoretical study of the mechanism of heat transfer between a vertical wall and loose solid particles along its side. The theoretical model was verified using experimental results obtaind by Baranski, A. [2], in those experiments the following operational parameters were varied: (Particle type, diameter, concentration and falling velocity).
The results were discussed, and the comparison between the theoretical and experimental investigations indicates good agreementSynthesis of p-Tert-Butylcalix[4]arenedibenzothiacrown Ethers and Their Complexation Properties with Transtion Metal Ions
Maher Abu Mallouh
Abstract
Design of Defense Hole System For Biaxially-Loaded Plate With a Single Central Circular Hole
Montasser Tahat
Salih Akour, Saad Habali
Abstract
Stress concentration associated with a single central circular hole in Biaxially-Loaded plates can be reduced by up to 22 %. With such a reduction in the maximum stress level the improvement in fatigue life of a structural part can be very significant. This significant reduction is made possible by introducing elliptical auxiliary holes close to the main holes in the areas of low stresses along the principal stress direction. The introduction of these holes in such places helps in smoothing the principal stress trajectories past the main hole. In the present paper, a systematic study based on univariate search optimization method is undertaken by using Finite Element Analysis (FEA) to determine the optimum size and location for an auxiliary defense hole system. The results are validated by using the RGB-photoelasticity. The experimental and the FEA results show good agreement. Three main goals are achieved by introducing such holes: material reduction, maximum stress reduction and working as crack arrest in case a crack propagates.
Models of Interaction of Sounding Radar Signal with Turbulized Meteorological Objects
Abstract
Simulation results of reflected signals from turbulized meteorological objects are discussed in this paper. In particular the correlation function and doppler spectrum with different turbulence intensity are simulated and discussed. A special algorithm of radar signal reflected from turbulized meteorological objects is developed. No preliminary assumption has been made about the statistical characteristics of received signals. However, transmitted signal parameters, radar characteristics and sounding conditions are used in these models. Multialternative classifications of weather objects, based on the degree of turbulence intensity have shown to result from the numerical simulation. Moreover, it is demonstrated that the turbulence detection reliability with variable intensities can be calculated based on the doppler spectrum width as an information parameter.
Orientation of the principal stresses along
Zerqa-Ma'in Fault
Abdullah A. Diabat
Ahmed I. Masri
Abstract
Stress inversion of fault-slip data was performed using an improved Right-Dihedral method, followed by rotational optimization. Fault–slip data (totaling 260) include fault planes, striations and sense of movement have been obtained mainly from Umm Rijam Chert Limestone Formation (Eocene) distributed at 13 stations along Zerqa Ma’in and the E-W sub-parallel major faults of the study area.
The inversion of data enabled the determination of 22 paleostress tensors of which 20 tensors have been related to strike-slip regime. Results show that two main stress states have been distinguished in the study area. The first one has the orientation of ? 1: 315/05, ? 2: 088/79 and ? 3: 225/10, whereas the second stress state has ? 1: 285/10, ? 2: 126/85 and ? 3: 015/05.
It is believed that the first stress state belongs to the Dead Sea Stress Field (DSS) with slight anticlockwise rotation, whereas the second one belongs to Syrian Arc Stress Field (SAS).
A Numerical Solution of the Coupled Heat Transfer Process During Freezing on a Finned Tube
Omar M. Hamdoon
Abstract
In the present study, a numerical model is proposed to analyze the freezing processes on finned tubes under coduction-controlled freezing, i.e., the liquid is set at its fusion temperature during the freezing process. Difficulties associated with the complex structure of the timewise changing physical domain (frozen region) has been overcome by applying a grid generation technique in conjunction with an ADI finite difference formulation to solve the governing equation through the frozen layer. The numerical results thus obtained are satisfactorily compared with the available experimental results of Sparrow et. al. ,[5], and the numerical procedure was found efficient and accurate.
Investigation of the Ice Formation on a Horizontal Tube Fitted With Two Vertical Longitudinal Fins
Omar M. Hamdoon
Ghalib Y. Kahwaji
The numerical model developed by the authors in a preceding paper [1], has been employed to solve the problem of freezing of well-mixed water at 0 ° C (conduction-controlled freezing) on a horizontal tube with two longitudinal vertical fins. The effect of geometry parameters (fin length and tube diameter), tube surface temperature and freezing time on the amount of ice produced, the shape of the freezing front and the rate of freezing is investigated.
Based on the analysis, a working formula for the mass of ice formed on the above mentioned geometry is correlated as:
M= 0.497 ( D T.t) 0.525 (D) 0.294 (Lf) 0.634?-Sn pseudomorphic growth on InSb (111) and ( 111) surfaces: a high resolution photoemission study
Mahmoud Abu-Samak
Abstract
The Sn/InSb interface and ?-Sn ultra-thin film formation on the sputter-annealed clean A- and B-type InSb(111) surfaces is studied by high-resolution UV photoelectron spectroscopy. The valence band and In-4d core levels, along with the relieving of the clean surface reconstructions, suggest a model for the interface formation at very low coverage. At higher Sn thickness, the In-4d and Sn-4d core level analysis show the growth of a good-quality ?-Sn(111)-(lxl) layer, with a slight In interdiffusion present on both substrates.