Assessment of wind energy to power solar brackish water greenhouse desalination units: A case study from Algeria

The Algerian desert dominates large parts of the country's vast territory, and Algeria is among the countries filling most of the world's largest desert. In fact the country is over 80% desert. Even though more than 80% of the population is located in the northern Mediterranean coastal zone, most of oil and gas fields are located in the country's vast southern desert called Sahara. Furthermore, the desert region is developed into a major tourist destination. This arid zone region is characterized by a lack of potable water. However, in addition to the abundant solar energy, the region is also endowed with important wind and brackish groundwater resources with different qualities. Therefore, a brackish water greenhouse desalination unit that is powered by wind energy is a good solution for desalting groundwater for irrigation purposes in this region. Brackish water can be used to cool the greenhouse, creating the proper climate to grow valuable crops. Moreover, at the same time the fresh water that is produced in this system may be sufficient for the irrigation of crops grown inside the unit. In this study, five typical regions in the Sahara were selected and investigated. These regions were selected since they were areas of traditional agriculture. The frequency distributions of wind speed data were collected from Surface Meteorology and Solar Energy (SSE) statistics developed by NASA and evaluated for a 10-year period. The distributions were used to determine the average wind speed and the available wind power for the five locations. The results indicated that the available wind energy is a suitable resource for power production and can be used to provide the required electricity for the brackish groundwater greenhouse desalination units.     

Parameter determination of Chaboche kinematic hardening model using a multi objective Genetic Algorithm

Chaboche model is a powerful tool to evaluate the cyclic behavior under different loading conditions using kinematic hardening theory. It can also predict the ratcheting phenomenon. To predict the ratcheting, it is required to determine the material parameters under strain control conditions. Although, these parameters can model the hysteresis loop fairly accurately, their ratcheting prediction does not have the same quality. A set of material parameters that could accurately predict both ratcheting and hysteresis loop is of great importance. The available models, generally for low cycle fatigue, are mostly complex and nonlinear. Therefore, an optimization procedure can be used for parameter determination and consequently improving the prediction of these models.Genetic Algorithm is a numerical approach for optimization of nonlinear problems. Using a multi objective Genetic Algorithm for Chaboche model, a set of parameters was obtained which improved both ratcheting prediction and hysteresis loop model. Two fitness functions were used for this approach. The proposed model was verified using Hassan and Corona’s experimental data conducted on CS 1026 low carbon steel. The model indicated a very good agreement in the case of uniaxial loading with the experimental data. The results of proposed model for biaxial loading histories are similar to the model by Hassan and his co-workers.     

8 GHz 1V, CMOS quadrature downconverter for wireless applications

The design and implementation of an 8 GHz CMOS quadrature downconverter, achieving simultaneously low voltage supply operation and good linearity is presented in this paper. This is achieved by relaxing the inherent tradeoff between power conversion gain and linearity governing all active mixers and implementing a mixer using a new version of the bias-offset technique. The quadrature generator uses active inductors embodied in the LO buffer, and provides easy tuning by relaxing the coupling between amplitude and phase tuning of the outputs. It also provides reduced power consumption by eliminating the buffers located between the quadrature generator and the mixers. A prototype implemented in a 0.18 μm CMOS technology occupies an area of 0.44 × 0.3 mm², operates from a 1V power supply and features an IIP3 of +3.5 dBm, an IIP2 of better than +48 dBm, an input compression point of −5.5 dBm, a power conversion gain of +6.5 dB for the mixers and a quadrature phase and amplitude matching of better than 1.5° and 1 dB respectively over a bandwidth of 100 MHz after tuning. The overall power consumption of the quadrature downconverter is 25.8 mW. Farsheed Mahmoudi was born in Tehran, Iran. He received his B.Sc. and M.Sc. degrees in Electronics from the University of Tehran, Tehran, Iran in 1997 and 2000 respectively. He is currently working toward the Ph.D. degree at the University of Toronto, Toronto, Canada. His research interests include the design and analysis of RF circuits and systems for wireless applications. C. Andre T. Salama received the B.A.Sc. (Hons.) M.A.Sc. and Ph. D. degrees, all in Electrical Engineering, from the University of British Columbia in 1961, 1962 and 1966 respectively. From 1962 to 1963 he served as a Research Assistant at the University of California, Berkeley. From 1966 to 1967 he was employed at Bell Northern Research, Ottawa, as a Member of Scientific Staff working in the area of integrated circuit design. Since 1967 he has been on the staff of the Department of Electrical and Computer Engineering, University of Toronto where he held the J.M. Ham Chair in Microelectronics from 1987 to 1997. In 1992, he was appointed to his present position of University Professor for scholarly achievements and preeminence in the field of microelectronics. In 1989–90, he was awarded the ITAC/NSERC Research Fellowship in information technology. In 1994, he was awarded the Canada Council I.W. Killam Memorial Prize in Engineering for outstanding career contributions to the field of microelectronics. In 2000, he received the IEEE Millenium Medal. In 2003, he received the Outstanding Lifetime Achievement Award from the Canadian Semiconductor Technology Conference for seminal and outstanding contributions to semiconductor device research and promotion of Canadian University research in microelectronics. In 2004, he received the NSERC Lifetime Achievement Award of Research Excellence for outstanding and sustained contributions to the field of microelectronics and the Networks of Centres of Excellence (NCE) Recognition Award for research excellence and outstanding leadership. He was associate editor of the IEEE Transactions on Circuits and Systems in 1986–88 and a member of the International Electron Devices Meeting (IEDM) Technical Program Committee in 1980–82, 1987–89 and 1996–98. He was the chair of the Solid State Devices Subcommittee for IEDM in 1998 and was a member of the editorial board of Solid State Electronics from 1984 to 2002. He is presently a member of the editorial board of the Analog IC and Signal Processing Journal and the Technical Program Committee of the International Symposium on Power Semiconductor Devices and ICs (ISPSD) and the Technical Program Committee of the International Symposium on Low Power Electronics and Design (ISLPED). He chaired the technical program committee of ISPSD in 1996 and was the general chair for the conference in 1999. Dr. Salama is the Scientific Director of Micronet, a network of centres of excellence focussing on microelectronics research and funded by the Canadian Government and Industry. He has published extensively in technical journals, is the holder of eleven patents and has served as a consultant to the semiconductor industry in Canada and the U.S. His research interests include the design and fabrication of semiconductor devices and integrated circuits with emphasis on deep submicron devices as well as circuits and systems for high speed, low power signal processing applications. Dr. Salama is a Fellow of the Institute of Electrical and Electronics Engineers, a Fellow of the Royal Society of Canada, a Fellow of the Canadian Academy of Engineering, a member of the Association of Professional Engineers of Ontario, the Electrochemical Society and the Innovation Management Association of Canada.     

Cytotoxicity and Cell Cycle Effects of Bare and Poly(vinyl alcohol)‐Coated Iron Oxide Nanoparticles in Mouse Fibroblasts

Super‐paramagnetic iron oxide nanoparticles (SPIONs) are recognized as powerful biocompatible materials for use in various biomedical applications, such as drug delivery, magnetic‐resonance imaging, cell/protein separation, hyperthermia and transfection. This study investigates the impact of high concentrations of SPIONs on cytotoxicity and cell‐cycle effects. The interactions of surface‐saturated (via interactions with cell medium) bare SPIONs and those coated with poly(vinyl alcohol) (PVA) with adhesive mouse fibroblast cells (L929) are investigated using an MTT assay. The two SPION formulations are synthesized using a co‐precipitation method. The bare and coated magnetic nanoparticles with passivated surfaces both result in changes in cell morphology, possibly due to clustering through their magnetostatic effect. At concentrations ranging up to 80 × 10^?3 M , cells exposed to the PVA‐coated nanoparticles demonstrate high cell viability without necrosis and apoptosis. In contrast, significant apoptosis is observed in cells exposed to bare SPIONs at a concentration of 80 × 10^?3 M . Nanoparticle exposure (20–80 × 10^?3 M ) leads to variations in both apoptosis and cell cycle, possibly due to irreversible DNA damage and repair of oxidative DNA lesions, respectively. Additionally, the formation of vacuoles within the cells and granular cells indicates autophagy cell death rather than either apoptosis or necrosis.     

Numerical study of natural convection cooling of horizontal heat source mounted in a square cavity filled with nanofluid

This paper presents a numerical study of natural convection cooling of a heat source horizontally attached to the left vertical wall of a cavity filled with copper-water nanofluid. The left vertical wall is kept at the constant temperature, while the other ones are kept adiabatic. The numerical approach is based on the finite volume method with a collocated grid arrangement. The SIMPLE algorithm is used for handling the pressure velocity coupling. In this study, the influence of some effective parameters such as: Rayleigh number, location and geometry of heat source and solid concentration are studied and discussed. Results are presented in the form of streamlines, isotherms, and average Nusselt number. The results show that dimension of the heat source is an important parameter affecting the flow pattern and temperature field, so that the average Nusselt number decreases with an increase in the length of the heater. It is also observed that at a given Rayleigh number and definite heat source geometry, the average Nusselt number increases linearly with the increase in the solid volume fraction of nanofluid. The increase of Rayleigh numbers strengthens the natural convection flows which leads to the decrease in heat source temperature. The algorithm and the computer code have been also compared with numerical results in order to verify and validate the model.     

Parameter estimation of autoregressive signals from observations corrupted with colored noise

This paper presents a new method for estimation of the parameters of a noisy autoregressive (AR) signal using observations corrupted with colored noise. This method is an improved least-squares (ILS) based method that combines low-order and high-order Yule–Walker equations. The performance of the proposed method is illustrated using computer simulations.     

Energy and exergy analyses of GAX and GAX hybrid absorption refrigeration cycles

In this paper, the GAX and GAX hybrid absorption refrigeration cycles are studied and compared from the viewpoint of both first and second law of thermodynamics. Exergy analyses were performed in order to calculate the total exergy destruction rate within the cycles and also reveal the contribution of different components to the destructions. In order to evaluate the efficiencies of the cycles at different working conditions, particularly from the viewpoint of the second law, parametric studies were also performed. It was found that in both cycles the generator temperature (T_gen) has more influence on the second law efficiency whereas, the coefficient of performance (COP) of the cycles are comparatively less affected by this temperature. An increase of about 75% in the second law efficiency of the GAX cycle was found as the generator temperature was varied from 400 to 440 K. With this variation of the generator temperature, the increase in the corresponding COP was around 5%. In addition, compared to that in the GAX cycle, the maximum value of exergetic efficiency in the GAX hybrid cycle occurs at a slightly higher value of T_gen.