Biogas combustion is a very essential topic for the development of many industrial combustion systems and engines. This fuel can replace current fossil fuels used in burners, engines, and many other applications. Understanding the combustion characteristics of this fuel and its stability in highly turbulent flames of practical interest is the aim of this work. The percentage of CO2 in Biogas varies between 25% and 45%, which affects the combustion stability and flame structure. The present work shows that the generation of Biogas is improved by adding Ni-Co-Ferrite or Ni-ferrite nano-additives. In this work, we selected 25 flames of mixtures of natural gas and CO2, where the ratio of CO2 varies from 0% to 40%. The flames are generated in a concentric flow slot burner that produces planar two-dimensional flames. The stability characteristics and the flame structure were investigated. The flame structure is presented in …

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The aim of this study is to evaluate and improve student thermal sensation in the open spaces of the Faculty of Engineering, Assiut University, Egypt using different shading strategies. Firstly, the thermal conditions of outdoor spaces were evaluated based on field measurements in different locations of shaded outdoor spaces between educational buildings within the Faculty of Engineering. Then, the microclimate model ENVI-met was applied to evaluate the impact of different shading scenarios on improving student thermal comfort. Also, the Thermal Sensation Vote (TSV) of the was studied by a questionnaire survey using the 118 effective questionnaire responses of the student sitting in the spaces between buildings. Hence, the results concluded that high air temperature is found in most outdoor open spaces, especially in the sitting area with low trees density and high Sky View Factor (SVF). Similar results were obtained by the TSV analysis. In addition, a significant reduction in the Predicted Mean Vote (PMV) values resulted from the ENVI-met simulation model with an average temperature difference of 0.7 °C due to increasing tree density for the main open space. Thus, it is recommended to increase greenery and tree density, to reduce heat stress and create student thermal comfort in outdoor.

Several municipal seismic vulnerability investigations have been identified pounding of adjacent structures as one of the main hazards due to the constrained separation distance between adjacent buildings. Consequently, an assessment of the seismic pounding risk of buildings is superficial in future adjustment of design code provisions for buildings. The seismic lateral oscillation of adjacent buildings with eccentric alignment is partly restrained, and therefore a torsional response demand is induced in the building under earthquake excitation due to eccentric pounding. In this paper, the influence of the eccentric seismic pounding on the design demands for adjacent symmetric buildings with eccentric alignment is presented. A mathematical simulation is formulated to evaluate the eccentric pounding effects on the seismic design demands of adjacent buildings, where the seismic response analysis of adjacent buildings in series during collisions is investigated for various design parameters that include number of stories; in-plan alignment configurations, and then compared with that for no-pounding case. According to the herein outcomes, the effects of seismic pounding severity is mainly depending on characteristics of vibrations of the adjacent buildings and on the characteristics of input ground motions as well. The position of the building wherever exterior or interior alignment also, influences the seismic pounding severity as the effect of exposed direction from one or two sides. The response of acceleration and the shear force demands appear to be greater in case of adjacent buildings as seismic pounding at different levels of stories, than that in case of no-pounding buildings. The results confirm that torsional oscillations due to eccentric pounding play a significant role in the overall pounding-involved response of symmetric buildings under earthquake excitation due to horizontal eccentric alignment.

Numerous urban seismic vulnerability studies have recognized pounding between adjacent structures as one of the main risks for neighbouring buildings due to the restricted separation distance. The seismic pounding could produce damages that range from slight non-structural to serious structural damage that could even head to a total collapse of buildings. Therefore, an assessment of the seismic pounding risk of buildings is indispensable in future calibration of seismic design code provisions. Thus, this study targets to draw useful recommendations for seismic design through the evaluation of the pounding effects on adjacent buildings. A numerical simulation is formulated to estimate the pounding effects on the seismic response demands of three adjacent buildings in series with different alignment configurations. Three adjacent buildings of 3-storey, 6-storey and 12-storey MRF buildings are combined together to produce three different alignment configurations; these configurations of adjacent buildings are subjected to nine ground motions that are absolutely compatible with the design spectrum. The nonlinear time-history is performed for the evaluation of the response demands of different alignment configurations of the adjacent buildings using structural analysis software ETABS. Various response parameters are investigated such as displacement, acceleration, storey shear force mean and maximum responses, impact force and hysteretic behaviour. Based on the obtained results, it has been concluded that the severity of the seismic pounding effects depends on the vibration characteristic of the adjacent buildings, the input excitation characteristic and whether the building has interior or exterior alignment position, thus either exposed to one or two-sided impacts. Seismic pounding among adjacent buildings induces greater shear force and acceleration response demands at different story levels for the high rise building, while the response could be reduced in the short buildings compared to that of no-pounding case. The effect of poundings of adjacent buildings seems to be critical for most of the cases and, therefore, the structural pounding phenomenon is rather detrimental than beneficial.

This paper presents a proposed design procedure of a Wireless Power Transfer (WPT) system based on high efficiency offset reflector antennas fed by conical horns. The system's performance evaluation is also demonstrated. The antennas in the transmitter and receiver sides of the proposed WPT system are symmetric. The performance of the system is optimized by calibrating the feeding horns and the offset reflector's dimensions to minimize the path and reflection losses of the proposed WPT system. The results show that correct line of sight alignment of the transmitter and receiver enhances the efficiency of the system. With an operating frequency of 6 GHz and 1 W of power transfer over a distance of 12 m between the transmitter and receiver, the system attains a total transfer efficiency of 62.9 %.

The objective of the study is to investigate the influence of seismic analysis of tunnel systems (single and twin tunnels). The seismic analysis is significant for tunnel projects in urban cities to avoid the collapse of tunnels in this crowded city due to displacements generated as a result of earthquake waves. A case study is The Greater Cairo metro line No.4, Phase No.1. To evaluate the influence of seismic waves on single and twin tunnels, four cases were simulated, the first case of a single tunnel and three cases of twin tunnels. For more serious understanding of the issue of seismic waves on twin tunnels, the horizontal, vertical and diagonal alignment are analyzed.. Total displacement was presented for tunnel systems. Moreover, induced internal forces in tunnel lining have been computed. The paper presents a two-dimensional model using numerical simulations by PLAXIS program. Based on the calculated result, a higher displacement occurs in tunnel lining during the earthquake. The maximum change of internal forces during an earthquake occurs in shear force, then bending moment. Moreover, the normal force of tunnel lining is less affected by seismic actions.

Spillways usually used for escaping water from the U.S. having a high-water level, to D.S. having a low water level in most of the diversion head structures through water streams. The D.S. of such spillways usually suffers from the destructive impacts of the generated kinetic energy of the flowing water, having a very high speed, which may cause cavitation in such spillways body. In the present work, some geometrical treatments on the back of the spillway body, are introduced for increasing its efficiency in dissipating the kinetic energy of the flowing water, having great potential energy, and improving the flowing water quality by increasing its dissolved oxygen content, through generating huge aeration at the flow in the back, in addition to prevent cavitation which may occur, and generated on the back of the spillway body. Previous studies proved that the stepped back of the spillway body is one of the most practicable trails done for achieving the above-mentioned goals. In this paper, a review of previous authors` technical methods to obtain the best design of the spillway geometric that dissipates high values of the kinetic energy and improving the flow aeration.is highlighted.

The research for alternative fuels increased rapidly to mitigate the pollution problems resulting from using conventional fuels in internal combustion engines. Natural gas (NG) appears the most promising alternative due to its low prices and availability around the world. In this paper, a two-zone, zero-dimensional (0-D) model for the simulation of dual fuel NG-diesel engine is developed to study the performance of the engine with a proposed technique of NG early direct injection. The model is composed of several sub-models that are based on semi-empirical formulas. NG is modeled as being directly injected at the beginning of the compression stroke. The model is applied to study the performance of HELWAN M-114 diesel engine using dual fuel of NG and diesel fuels as a case study. The results indicate that using NG early direct injection technique (EDI) results in increasing the volumetric efficiency and hence the brake power of the engine compared to the intake manifold induction (IMI) of NG with air through the intake manifold. The percentage increase in brake power is 8.7% at NG mass ratio in the total fuel (the supplement ratio (SR)) of 90% at full load. To evaluate the proposed technique, results obtained by varying the engine load and the SR. Results indicate that the slow burning rate of NG results in decrease in the brake thermal efficiency by 3.5% and increases in brake specific fuel consumption with a percentage of 10.2% at 90% SR and full load. However, a great advantage of increasing the SR is the reduction in NOx and soot emissions particularly at high engine loads where they were reduced with percentages of 28.6% and 86%, respectively at 90% SR and full load condition.

This paper introduces a design for an ultralowpower electromyogram (EMG) signal amplifier with low noise operation. The design consists of two stages, the first stage is highly efficient but supply-sensitive single ended amplifier and the second stage is differential, to improve the supply rejection ratio and common mode rejection ratio. Each stage is configured with cascode MOSFET transistors to increase the gain value. The proposed design is simulated by 130 nm CMOS, and its results are reported. The design achieves 60.62 dB mid-band gain with bandwidth of 1.72kHz. Using a supply voltage of 1.1 V, the amplifier consumes 1.03 μA of current. Input referred noise is 3.006 μVrms. The common mode and power supply rejection ratios are above 49.05 dB and 55.72 dB respectively.