Energy in Egypt: Resources, uses, and outlook to 2000

The present and future energy situations in Egypt are assessed and evaluated. Data on energy resources and reserves, together with the patterns of energy uses in the different sectors, are presented. In the light of the available data, an outlook to the year 2000 is discussed.     

The abundance of some elements in hair and nail from the Machakos district of Kenya

Hair and nail samples collected from a population group in the Machakos District, Kenya, were studied for their elemental content using instrumental neutron activation analysis. In order to test for the type of probability distribution, frequency histograms of elemental concentration of 9 elements in hair, both for male and female subjects in the population, were plotted and λ²-tests applued for normal distributions. Plots of cumulative frequency, using logarithmic probability paper, were used to illustrate the lognormal nature of the distributions of elements in hair such as Hg. Arithmetic and geometric means with respective standard deviations are presented for 15 elements in hair, divided into four groups according to age and sex. Results from nail samples available for a small number of subjects are also presented for males and females. Differences in concentrations for the various groups were investigated and discussed. Comparison was made with published data for a number of different populations.     

Electrical properties and longitudinal modulus of superconductor/polymer NdBa2Cu3O7−δ/PVC composites

High temperature superconductor NdBa₂Cu₃O_7–/poly(vinyl chloride) (Nd123/PVC) composites have been prepared by cold press and hot press methods. Addition of PVC resulted in increase of the electrical resistivity with percolation occurring between 0.3 and 0.5 Nd123 volume fraction for both preparation methods. Although the samples showed some form of magnetic levitation at liquid nitrogen temperature, they do not show any zero-resistance temperature indicating the lack of effective superconducting percolative path. The density deviates from the linear calculated value with increasing Nd123 content at 0.3 volume fraction for the cold press and at 0.6 for the hot pressed samples due to increasing porosity. X-ray powder diffraction patterns suggest that the Nd123 crystals tend to align when the composites are prepared by hot press method. A resistance anomaly is observed at 90 K in the hot press composites indicating improved electrical contact between the aligned Nd123 grains. The longitudinal modulus increases as Nd123 content is increased.     

To disassemble or not: a computational methodology for decision making

Environmentally conscious manufacturing is an important paradigm in today’s industrial practices and disassembly is a crucial factor in implementing this paradigm. Disassembly allows the reuse and recycling of parts and products that reach their “death” after their life cycle ends. There are many questions that must be answered before a disassembly decision can be reached. The most important question is economical. The cost of disassembly versus the cost of scrapping a product is always considered. This paper develops a computational methodology that allows decision-makers to calculate the disassembly cost of a product before it is built. The methodology makes it simple to perform “what if” scenarios fairly quickly. A Java based application has been developed to implement this methodology and it uses computational algorithms and a graphical user interface to enable designers to simulate product designs. The front end user interface is a Java based application while the back-end is the combination of a data parser and disassembly engine, which also makes use of Java and XML technologies. The disassembly engine performs calculations based on data represented in an XML data store and runs as the back-end component of the computational tools. The user interface has the ability to display a dynamically configurable disassembly tree. The disassembly knowledge is represented in XML format to allow robust and scalable parsing and processing of the various disassembly alternatives that correspond to the configurable disassembly tree. Examples are presented to demonstrate the implementation and capabilities of the computational design methodology presented in this paper. Received: March 2005 / Accepted: January 2006     

Internet telephony signaling

The term “multimedia session” refers to the integration of data coming from various sources, such as sound, video and text, within a computer application. Telephony over the Internet is among the more exciting current developments. The signaling of a telephone call consists of the set of messages and procedures used to establish a connection, to request changes in communication bandwidth, to obtain the message status for the end points participating in the conversation, and to close the link. At present there exist two competing signaling protocols for Internet telephony, viz., the H.323 protocol sponsored by the ITU and the Session Invitation Protocol (SIP) sponsored by the IETF. Each of them supplies its own signaling mechanisms.

In this paper, these two protocols in terms of their main functionalities are compared. Based on the results of this comparison, a Client/Server architecture for the development of an application that supports a basic SIP implementation, as well as the formulation of requests allowing the establishment and the disconnection of communications between a number of users in a multimedia session are then defined.     

Deformation of NiTiCu shape memory single crystals in compression

Single-crystal orientations of NiTi10Cu alloys were studied under incremental, cyclic compression conditions to establish the pseudoelastic and shape memory response of this class of alloys. This material exhibits a two-step transformation involving cubic to orthorhombic martensite (B2 → B19) followed by orthorhombic to monoclinic martensite (B19 → B19′). The transformation parameters (shear magnitudes and directions for habit and twin planes) were determined associated with the B2 → B19 transformation. The growth of monoclinic martensite correspondent variant pairs (CVPs) emanating from the orthorhombic structure was also analyzed. The transformation strain for the B2 → B19 case was orientation dependent and lower than the B19 → B19′ transformation in compression for all orientations except those near the [001] pole. The experimental results show that the critical transformation stress is orientation dependent and is in the range 30 to 58 MPa. Orientations that exhibit lower transformation stress (or high resolved shear stress factors, [100] and [012]) produce higher recoverable strains (as high as 4 pct), while other orientations ([011], [111], and [123]) with lower resolved shear stress factors result in recoverable strains less than 3 pct. At higher strains, inelastic deformation develops, limiting recoverability. The recoverable strains are lower than the theoretical values for two main reasons: the transformation is curtailed first by austenite slip and subsequently by martensite slip, and the orthorhombic structure does not fully transform to the monoclinic martensite.     

Phosphorus removal by an 'active' slag filter-a decade of full scale experience

Active filters, which facilitate phosphorus (P) removal via precipitation and/or adsorption, offer a promising 'appropriate technology' for upgrading small wastewater treatment systems. Research on active filters for P removal using steel slag material has been conducted in laboratories across the world, however, field experiments have been limited and long-term data is practically non-existent. This paper presents a decade of experience on P removal by active slag filters at a full-scale treatment plant. During 1993-1994 the filter removed 77% of the total phosphorus (TP), and over the first 5 years of the filter's operation it reduced the mean effluent TP concentration to 2.3 mgl(-1). However during the sixth year of operation P removal was significantly reduced. Over the 11 years of monitoring, 22.4 tonnes of TP was removed by the filter, 19.7 tonnes of this in the first 5-year period. It was determined that the slag material maintained its maximum removal potential until reaching a P-retention ratio of 1.23 kg TP per tonne of slag. This paper provides the first long-term field data for slag filters, and shows that they can provide P removal for a half a decade before filter replacement/rejuvenation is required.     

Hybrids for finishing cotton fabric with durable handle performance

New poly(acrylic acid/epichlorohydrin) hybrids were prepared under different polymerization conditions and the proper hybrid was used as a stiffening agent or what may be called hand builder. The latter was incorporated in dimethyloldihydroxy ethylene urea (DMDHEU) finishing formulation and the onset of this on fabric performance as monitored by nitrogen content, wrinkle recovery angle, tensile strength, stiffness, dyeability, and oily stain release was studied. Durability of the new finish was also examined. Results disclose substantial improvement in fabric performance and imply that the hybrid in question acts as a durable hand builder through fixation via its hydroxyl groups within the DMDHEU finish which, in turn, is chemically bonded to cotton cellulose. Scanning electron microscopy of finished fabric revealed that this chemical bonding resulted in hybrid encapsulation, deposition and/or coating of fabric fibers.     

An adaptive multiscale inverse scattering approach to photothermal depth profilometry

Photothermal depth profilometry is formulated as a nonlinear inverse scattering problem. Starting with the one-dimensional heat diffusion equation, we derive a mathematical model relating arbitrary variation in the depth-dependent thermal conductivity to observed thermal wavefields at the surface of a material sample. The form of the model is particularly convenient for incorporation into a nonlinear optimization framework for is particularly convenient for incorporation into a nonlinear optimization framework for recovering the conductivity based on thermal wave data obtained at multiple frequencies. We develop an adaptive, multiscale algorithm for solving this highly ill-posed inverse problem. The algorithm is designed to produce an accurate, low-order representation of the thermal conductivity by automatically controlling the level of detail in the reconstruction. This control is designed to reflect both (1) the nature of the underlying physics, which says that scale should decrease with depth, and (2) the particular structure of the conductivity profile, which may require a sparse collection of fine-scale components to adequately represent significant features such as a layering structure. The approach is demonstrated in a variety of synthetic examples representative of nondestructive evaluation problems seen in the steel industry.The work of authors E. L. Miller and I. Yavuz was supported by a CAREER Award from the National Science Foundation MIP-9623721, an ODDR&E MURI under Air Force Office of Scientific Research contract F49620-96-1-0028, and the Army Research Office Demining MURI under grant DAAG55-97-1-0013. The work of authors L. Nicolaides and A. Mandelis was supported by a research contract from Material and Manufacturing Ontario (MMO).     

Grid-Tied PV-BES system based on modified bat algorithm-FLC MPPT technique under uniform conditions

Neural Computing and Applications - Grid-connected photovoltaic (PV) systems play an important role in reducing emissions resulting from conventional fossil-fuel-based power plants. However, in...