WAVE PATTERN PRODUCED BY A HEAT SOURCE MOVING WITH CONSTANT VELOCITY ON THE TOP OF AN INFINITE PLATE

Within the framework of linear, isotropic elasticity theory the wave pattern produced by a heat source moving with constant velocity on the top of an infinite plate is computed. Both the transient effects associated with the initial conditions and the damping of the waves are neglected. If the travel speed of the heat source is smaller than the velocity of the surface waves, dispersive flexural waves will be excited. The frequency of these waves is proportional to the square of the wave number if the wavelength is much larger than the thickness of the sheet. In this limiting case it is found that the crest of the waves makes an angle of 90 degrees with the travel direction, and this result is independent of the travel speed as long as the parabolic approximation remains valid for the dispersion relation of flexural waves.     

Tunable single longitudinal mode S-band fiber laser using a 3 m length of erbium-doped fiber

In this paper a tunable single-longitudinal mode (SLM), short-wavelength band (S-band) fiber laser using a conventional erbium-doped fiber (EDF) with a length of 3?m and a step index erbium dopant profile as opposed to the commonly used depressed cladding erbium-doped fiber (DC-EDF) is proposed and demonstrated. The proposed SLM fiber laser has a tuning range of 1496 to 1507?nm in a ring configuration using two 0.15?m of EDF which acts as saturable absorbers (SAs). The highest peak power measured is about ?0.6?dBm at a wavelength range of 1502 to 1507?nm. The measured signal-to-noise ratio (SNR) is approximately 74?dB for the same wavelength range. The line-width of the SLM output is measured to be 140?kHz.     

Crystallisation of ferrous sulphate heptahydrate: Experiments and modelling

Crystallisation is an industrially important unit operation for purifying and separating chemical mixtures. A generic crystallisation modelling framework has been implemented in the general process modelling system (gPROMS) software (of PSE, UK). This framework can be used to model the batch cooling crystallisation of ferrous sulphate heptahydrate (FSH). The parameter estimation and sensitivity of the predicted results with various numerical parameters was studied for batch crystalliser. An Excel “front‐end” to the gPROMS model was developed to facilitate the interactive use of the model. © 2011 Canadian Society for Chemical Engineering     

PETROPHYSICAL CHARACTERISTICS OF THE MESSINIAN ABU MADI FORMATION IN THE BALTIM EAST AND NORTH FIELDS,OFFSHORE NILE DELTA,EGYPT

Baltim East and North fields in the offshore Nile Delta produce gas‐condensate from accumulations located in the northern portion of the Abu Madi palaeovalley. The hydrocarbons in the Abu Madi Formation are present in sandstone reservoir units referred to as the Level III Main and Level III Lower. In this paper, the petrophysical characteristics of these reservoir units in the Baltim area are described using data from wireline logs (gamma‐ray, density, neutron, sonic and resistivity) from fourteen wells and core data from one well. Results of wireline log and core analyses indicate that the Level III Main can subdivided into two sandstone‐dominated intervals (both interpreted as sandbar deposits) separated by a shale‐rich interval which is a partial barrier to fluid flow. Effective porosity is 9–18.5% and permeability 40–100 mD. Sandstones in the Level III Lower are interpreted as braided channel facies and have effective porosity of 12.5–22% and permeability of 100–500 mD. Isoparametric maps for the Abu Madi Formation sandstone reservoirs based on log and core interpretations show the influence of depositional facies on petrophysical characteristics and can be used to assess possible targets for future exploration and development.     

Preparation and in vitro evaluation of new pH‐sensitive hydrogel beads for oral delivery of protein drugs

New biodegradable pH‐responsive hydrogel beads based on chemically modified chitosan and sodium alginate were prepared and characterized for the controlled release study of protein drugs in the small intestine. The ionotropic gelation reaction was carried out under mild aqueous conditions, which should be appropriate for the retention of the biological activity of an uploaded protein drug. The equilibrium swelling studies were carried out for the hydrogel beads at 37°C in simulated gastric (SGF) and simulated intestinal (SIF) fluids. Bovine serum albumin (BSA), a model for protein drugs was entrapped in the hydrogels and the in vitro drug release profiles were established at 37°C in SGF and SIF. The preliminary investigation of the hydrogel beads prepared in this study showed high entrapment efficiency (up to 97%) and promising release profiles of BSA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development of isotropic compatible HDPE/PP blends for structural applications

In an attempt to provide superior products for the structural applications, this study aimed at preparing isotropic compatible high density polyethylene (HDPE)/ polypropylene (PP) blends without the use of the expensive compatibilization technique. Morphological and structural characterizations of the homopolymers and blends were carried out. In addition, some of the structurally important mechanical and thermal properties were characterized. Such characterizations were performed to investigate whether or not the blends are compatible and therefore acceptable for the structural applications. Scanning electron microscope (SEM) micrographs of the blend samples indicate that the interfacial adhesion between HDPE and PP phases is intimate in the 5/95 HDPE‐PP, good in the 85/15 HDPE‐PP and 95/5 HDPE‐PP, fair in the 30/70 HDPE‐PP and very poor in the 50/50 HDPE‐PP. Similarly, mechanical and thermal responses of the first three blends are remarkable. The 30/70 HDPE‐PP blend displays a fairly good performance. Whereas, the properties of the 50/50 HDPE‐PP blend are very poor. This decides that the first three blends are compatible and, therefore, structurally attractive materials. The fourth is partially compatible and, as a consequence, can be rather acceptable for the structural applications. However, the fifth is incompatible and, of course, is not acceptable for such applications. On the other hand, SEM micrographs and differential scanning calorimetry results indicate that the crystalline structures of individual polymers are appreciably affected by blending. Additionally, the study reveals that the end use performance of blends is strongly dependent on the crystalline structure changes occurring in each component due to blending as well as the compatibility between the blend components. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and applications of reactive carbohydrates. III. Preparation and methylolation of polyacrylamide-carboxymethyl cellulose graft copolymers

Carboxymethyl cellulose (CMC) was treated with HCl at 80°C for different time periods (15 – 60 min). The hydrolyzed CMC samples as well as the original sample were graft copolymerized with acrylamide using K₂S₂O₈ as initiator. It was disclosed that the increasing duration of acid hydrolysis is accompanied by a progressive increment in the copper number of CMC, meanwhile its carboxyl content decreases. Acid hydrolysis enhances significantly the susceptibility of the CMC toward grafting. The latter reduces the copper number of the hydrolyzed CMC samples most probably via conversion of the aldehydic to carboxylic groups under the action of K₂S₂O₈ during grafting. Grafting also reduces the carboxyl content of the original CMC sample while increasing those of the hydrolyzed CMC samples. Methylolation of the polyacrylamide-CMC graft copolymers results in reactive finishes. When the latter were applied to cotton fabric according to the conventional pad-dry-cure method followed by a thorough washing, the fabric retained ca. 86% of the finish derived from the copolymer of CMC and 92% of finishes derived from the copolymers of hydrolyzed CMC.     

Application of the complex variable boundary element method to solving potential problems in doubly connected domains

The complex variable boundary element method (CVBEM) developed by Hromadka for the solution of potential problems in simply connected domains is extended to the solution of heat conduction problems in doubly connected domains. A cut is made in the doubly connected domain, and it was found that the complex potentials along the cut do not cancel out but result in a complex stream function that plays the role of perturbation in the nodal equations. Cauchy–Riemann conditions are used to derive additional equations which relate the stream functions and the boundary heat fluxes and potentials when Neumann and Robin conditions are imposed on the boundaries. The resulting nodal equations are expressed in matrix form, and coding rules and methods for checking the matrix elements are developed. Three solution methods (implicit, explicit and hybrid) are described, and by means of examples, the efficacy of these methods is discussed and compared.     

New modified design of high direct current bolted busbar joints

A method is presented for estimating the dimensions of the bolts joining the two parts of an L-shaped rectangular busbar joint carrying direct current. The current distribution along the two joint parts and the corresponding electromechanical stresses are obtained. The method presented is the only exact available theoretical base for busbar joint bolts design     

Interaction of γ-rays with Some Alkali-Alkaline-Earth Borate Glasses Containing Chromium

The change in the visible spectra of some irradiated ternary borate glasses containing chromium has been studied by increasing the γ-ray doses with changing alkali content or increasing chromium concentration. In the glass without chromium, the γ-rays induce two absorption bands which are attributed to the formation of positive hole centers, whereas in the glass containing chromium at least three absorption bands are observed. The results showed that the visible absorption bands before and after γ-ray irradiation exhibited changes with the radiation dose and/or the chemical composition of the glass. The response of the glasses to γ irradiation is related to the creation of defect color centers, the approach of a saturation condition, and the possible photochemical effect on the transition metal.