Application of neural networks and machine learning in networkdesign

Communication network design is becoming increasingly complex, involving making networks more usable, affordable, and reliable. To help with this, we have proposed an expert network designer (END) for configuring, modeling, simulating, and evaluating large structured computer networks, employing artificial intelligence, knowledge representation, and network simulation tools. We present a neural network/knowledge acquisition machine-learning approach to improve the END's efficiency in solving the network design problem and to extend its scope to acquire new networking technologies, learn new network design techniques, and update the specifications of existing technologies     

Multi-User MIMO Mobile CDMA Uplink System Employing Turbo Coding and Joint Detection Through a Multipath Rayleigh Fading Channel

In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitter, the information bits are Turbo coded, then interleaved and passed through a serial-to-parallel converter. The channel is assumed bad urban suffering from multipath Rayleigh fading resulting in inter-symbol and multiple access interferences (ISI and MAI). At the front-end of the receiver, a number of receiving antennas are used followed by a joint multi-user estimator based on the Minimum Mean Square Error Block Linear Equalizer (MMSE-BLE).Computer simulations demonstrate a significant performance improvement in both single user and multi-user cases.This paper depends in parts on that presented at the 11th European Wireless Conference, Cyprus, Nicosia, pp. 187–192, April 2005. Yasmine A. Fahmy was born in Guiza, Egypt, on June 4, 1976. She received the B.Sc., M.Sc. and Ph.D. degrees in Communication and Electronics engineering from Cairo University, Egypt on 1999, 2001 and 2005 respectively. She is presently an assistant professor at Cairo University, Egypt. Her current field of interest is wireless communication and channel estimation. Hebat-Allah M. Mourad received her B.Sc., M. Sc. and Ph.D. degrees in electrical communication engineering from Cairo University, Egypt, in 1983, 1987 and 1994 respectively. Since 1983, she has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently associate professor there. Her research interests include optical fiber communications, mobile and satellite communications. Emad K. Al-Hussaini received his B.Sc degree in Electrical Communication Engineering from Ain-Shams University, Cairo, Egypt, in 1964 and his M.Sc and Ph.D. degrees from Cairo University, Giza, Egypt, in 1974 and 1977, respectively. From 1964 to 1970, he was with the General Egyptian Aeroorganization. Since 1970, he has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently professor there. He was a research fellow at Imperial College, London, UK, and at the Moore School of Electrical Engineering, University of Pennsylvania, Philadelphia, PA, USA, in the academic years 1976/1977 and 1981/1982, respectively. In 1990, he received the Egyptian national encouragement award for outstanding engineering research. He has written several papers for technical international journals and conferences. His research interests include signal processing, fading channel communication, modulation, and cellular mobile radio systems. Dr Al-Hussaini is a senior member of IEEE. He is listed in Marquis Whos Who in the World and in the IBC (International Biographical Center, Cambridge) for outstanding people of the 20th century.     

Performance and buffering requirements of Internet protocols overATM ABR and UBR services

ATM networks are quickly being adopted as backbones over various parts of the Internet. This article studies the dynamics and performance of the TCP/IP protocol over the ABR and UBR services of ATM networks. Specifically the buffering requirements in the ATM switches as well as the ATM edge devices. It is shown that with a good switch algorithm, ABR pushes congestion to the edges of the ATM network while UBR leaves it inside the ATM portion. As a result, the switch ABR buffer requirement for zero-packet-loss high-throughput TCP transmission is a sublinear function of the number of TCP connections     

Well-differentiated liposarcoma of the hypopharynx

We report a case of subacute bowel obstruction due to a compression of the rectosigmoid junction by a chronically distended bladder, occurring in a 91-year-old male suffering from a long-standing diabetes mellitus and a prostatic adenoma. Radiographic, water-soluble contrast enema and pelvic CT features are reported.     

Numerical investigations on dynamic performance of stiffened box steel bridge piers

The aim of this paper is to carry out extensive numerical investigations about the effect of various structural parameters on the dynamic performance of stiffened box steel bridge pier under a strong earthquake ground motion. The considered structural parameters are the local slenderness ratios of stiffener and stiffened wall as well as the global slenderness ratio of the pier. In the present study, all investigated piers are made of high tensile steel with high yield ratio. The non-linear time history analyses are carried out using in-house Finite Element Program DYNAPSS, recently developed by the first author. This program is verified by comparing its results with the results obtained by the general FE program. In this program, the geometrical nonlinearity is considered on the bases of Total Lagrangian formulation, while the non-linearity of structural steel material is considered through implementation of modified multisurface cyclic plasticity model by which real characteristics of high tensile steel material such as, Plateau, Massing type of Bauschinger??s effect, disappearing of Plateau and cyclic strain hardening, are accurately modeled. The results are closely examined in respect with the damage index criterion. From this study, it is found that the increase in slenderness ratios of stiffener does not only increase the damage index, but also may lead to the full collapse. Furthermore, the damage index increases with the increase of local slenderness ratio of stiffened wall and the global slenderness ratio. Also, it is found that when the loacal buckling is not the dominant eigen mode and the pier behave as a single degree of freedom, the natural period has destructive effects when it is close to predominant period of the earthquake. Finally, contour plots of damage index values are presented. These contour plots may be greatly useful for the design of stiffened box steel bridge piers, where, critical values of structural parameters corresponding to certain value of damage index could be determined.     

A new LRBFCM-GBEM modeling algorithm for general solution of time fractional-order dual phase lag bioheat transfer problems in functionally graded tissues

The main objective of this article is to propose a new hybrid modeling algorithm based on combining local radial basis function collocation method (LRBFCM) and general boundary element method (GBEM) for solving time fractional-order dual phase lag bioheat transfer problems in functionally graded tissues. The LRBFCM was developed and implemented using an implicit time-stepping technique and Caputo time fractional derivative for solving the fractional-order governing equation without dual phase lags. Due to suitability of the GBEM for modeling of bioheat transfer in functionally graded tissues. Therefore, GBEM is applied for solving the dual phase lags governing equation without fractional-order derivative. The numerical results are depicted graphical forms to show the effects of functionally graded parameter, fractional-order parameter and anisotropy on the nonlinear temperature distribution. Also, these numerical results demonstrate the validity and accuracy of the proposed algorithm and technique.     

Thermally stable antimicrobial PVC/maleimido phenyl urea composites

Four novel antimicro bial maleimido phenyl urea derivatives were synthesized from N-[4-(chlorocarbonyl) phenyl] maleimide with phenyl urea derivatives (p-methyl, o-chloro and p-carboxy). They were characterized by FTIR, ¹H-NMR, mass spectra, elemental analyses and antimicrobial activities. These derivatives were investigated as thermal stabilizers for rigid poly(vinyl chloride) at 180 °C in air by measuring the rate of dehydrochlorination and the extent of discoloration. The results reveal the greater stabilizing efficiency of the investigated derivatives as shown by their longer thermal stability periods (Ts) and lower dehydrochlorination rates in relation to dibasic lead carbonate, cadmium-barium-zinc stearate and n-octyltin mercaptide industrial stabilizers. The stabilizing efficiency increases with the introduction of electron donating substituent groups in the aromatic ring of the stabilizer molecules. Moreover, the investigated stabilizers impart better color stability for the degraded samples as compared with the reference stabilizers.     

Viscosity and Gelatinization Characteristics of Hydroxyethyl Starch

Viscosity and gelatinization characteristics of corn and potato starches as well as their hydroxyethyl derivatives were investigated. The inherent viscosity increased from 164 in native corn starch to 209 in etherified one of DS 0.18. The etherified corn starch gelatinized at lower temperature than native corn starch due to their increase of DS. Maximum viscosity decreased from 93°C to 69°C for the modified corn starch. The retrogradation of starch was minimized by etherification as retrogradation ability of corn starch from its solution decrease from 22% to 6%. This is of great importance when starch is used as blood plasma volume expander. Variable results were obtained with etherified potato starch which might be due to its high contents of phosphorus.     

Stress dependence of water diffusion in epoxy resin

The effect of stress on the diffusion of water in glassy polymers is analytically treated. Utilizing the free volume concept the effect of stress on the free volume fraction is established and in turn is related to the diffusion coefficient yielding the following formula: D_σ = D_oe^{(6 to 10)σ/G} where D_σ and D_o are the diffusion coefficients in the presence and absence of stress respectively, G is the shear modulus, and σ is the stress. Experiments are described which demonstrate that in a bent epoxy bar, more water is picked up at the tension side than at the compression side. Theory and experiment are discussed and compared.     

LAI based trees selection for mid latitude urban developments: A microclimatic study in Cairo, Egypt

To study the leaf area index, LAI, based thermal performance in distinguishing trees for Cairo's urban developments, ENVI-met plants database was used as platform for a foliage modeling parameter, the leaf area density, LAD. Two Egyptian trees; Ficus elastica, and Peltophorum pterocarpum were simulated in 2 urban sites with one having no trees, whilst the second is having Ficus nitida trees. Trees LAD values were calculated using flat leaves' trees LAI definition to produce maximum ground solid shadow at peak time. An empirical value of 1 for LAI is applied to numerically introduce LAD values for ENVI-met.Basically, different meteorological records showed improvements for pedestrian comfort and ambient microclimate of the building using F. elastica. About 40–50% interception of direct radiation, reductions in surfaces' fluxes around trees and in radiant temperature T_mrt in comparison to base cases gave preferability to F. elastica. The lack of soil water prevented evapotranspiration to take place effectively and the reduced wind speeds concluded negligible air temperature differences from both base cases except slightly appeared with the F. elastica. Results show that a flat leaves tree if does not validate LAI of 1, the ground shading would not fulfill about 50% direct radiation interception and this value can be used as a reference for urban trees selection.Further simulations were held to investigate LAI value of maximum direct radiation interception.Performing additional simulations, F. elastica of LAI of 3 intercepted almost 84% of direct radiation and revealed implications about urban trees in practice and its actual LAI.