Novel pipelined serial/parallel multiplier

A novel unidirectional pipelined serial/parallel multiplier (PSPM) is presented. This design has halved the initial delay and reduces the number of latches by 10% of the conventional structure. An area-time criteria is used to compare the new architecture with the old PSPM.<>     

Single injection, double injection and negative resistance in gold-doped high-resistivity silicon

A simplified explanation is given for negative resistance in a semiconductor containing deep-lying donor and acceptor levels. A simple equation is derived for the breakover voltage and is verified by experimental studies of single and double-injection currents in gold-doped silicon.     

Distribution of trace metals in petroleum and its heavy refinery products

The distribution of trace metals between crude petroleum and its heavy products has been studied by emission spectrography. The highest concentration of V, Ni, Sb and Mg was associated with the asphaltic fraction. A correlation has been established between the V/Ni, V/Sb and Ni/Sb indices and the geologic age of petroleum. Examination of gas and diesel oils for suitability as catalytic cracking feedstocks has been made on the basis of their Ni equivalent. Lubricating oil was found to retain little or no trace metals from the parent crude oil. The relatively high V content of fuel oil can affect refinery equipment, distillation units and linings of industrial furnaces. Other trace metals are non-destructive or only slightly destructive.     

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.     

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     

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).     

Flexural properties of three-dimensional printed continuous wire polymer composites

Recently, continuous fibre reinforcement has been combined with three-dimensional (3D) printing to create stiffer printed components. This study investigates the effect of wire volume fraction, type of polymer matrix, and wire treatment on the flexural properties of 3D printed continuous wire polymer composites (CWPCs) through a design of experiment study. CWPC samples were printed using a modified, open-source 3D printer. The flexural properties were measured and compared to non-reinforced samples. An analytical model was developed to describe the stress distribution across unidirectional CWPCs as a function of the geometrical printing parameters, reinforcement dimensions, and material properties. Sample failure analysis was performed to investigate failure modes and offer insight into further enhancement of the composite’s properties.     

Gravity Separation of Silica Sands for Value Addition

A representative white sand sample was investigated for glass industry. Complete characterization of the sample was conducted. Chemical analysis of the sample showed that iron and alumina oxides reached 0.046% and 0.044%, respectively. Dry sieving was carried out to reject +0.6 mm and ?0.10 mm fractions from the sample. The classified ?0.6 + 0.1 mm product was directed to attrition scrubbing. The effect of pulp density, attrition impeller speed, attrition time and mode were studied. The attrition sand product was further subjected to gravity separation using “Wilfley” shaking table. Different working conditions of table separation i.e., sand feeding rate, stroke length, deck inclination, and dressing water flow rate were optimized. Results showed that the classified ?0.6 + 0.106 mm sand product contained 0.039% Fe₂O₃ and 0.041% Al₂O₃ matched the specifications for the fourth-quality sand for sheet and plate glass industry. However, iron and alumina oxides contents were further decreased to 0.025% and 0.0164% after the attrition process. The attrition product accepted as second quality for flint containers and table ware applications. The final sand product after shaking table contained 0.0180% Fe₂O₃ and 0.090% Al₂O₃, was applicable for the first quality for optical applications.     

Chemical composition of apricots affected by fruit size and drying methods

ABSTRACT

Combined practice of sulfuration and drying is widely applied for extending shelf life of fruits. The differences in fruit size are not taken into consideration during these applications and during fresh fruit consumption. In this study, effect of fruit size and drying methods (hot air-drying and sun drying) on the chemical composition of fresh and sulfurated apricot was investigated. Total drying times for sun drying and hot air-drying were 11?d and 51?h, respectively. A temperature gradient was applied during hot air-drying. The fruit size substantially affects the composition of both fresh and dried apricots. The results were subjected to principal component analysis. The small-sized fresh apricots discriminate themselves from large ones with higher amounts of phenolic compounds, whereas the large-sized fresh apricots contain more sugar and organic acids. Size classification and hot air-drying are advisable for high-quality dried apricot production.