Mechanical Engineering

Disappearance phenomena, in which salient visual stimuli do not register consciously, have been known to occur. Recovery from such phenomena typically occurs through change in some visual attribute, such as increase in luminance contrast or stimulus duration. Thus far, there have been no reports of cross-modal modulation of disappearance phenomena. In particular, what effect a cross-modal attentional cue has on sensory suppression is unknown. Here, we show that an adapted, flickered visual target that is synchronous with a brief sound appears more vivid than a similarly adapted, otherwise identical, visual target that is offset in time by more than 200 ms from the auditory cue. We argue that the brief auditory stimuli momentarily boost the concurrent signal of the adapted visual stimulus at a site downstream of the visual adaptation, thus causing the transient recovery from the visual adaptation. Repetitive visual cues cause significantly less recovery from visual adaptation than repetitive auditory cues, implying that there are functions a cross-modal cue can perform that a cue of the same modality cannot. Moreover repetitive auditory cues selectively prevent synchronous visual targets from undergoing visual adaptation. Ours is the first report of cross-modal modulation of a disappearance phenomenon.

Due the advances in the industrial processes, in which the cement industry is a major contributor, energy consumption and greenhouse gas emission has increased significantly. This paper reviews previous studies on energy saving, carbon dioxide emission reductions and the various technologies used to improve the energy efficiency in the cement industry. Energy efficiency measures for raw materials preparation, clinker production, products and feedstock changes, general energy efficiency measures, and finish grinding have been surveyed. It was found that the largest recorded amounts of thermal energy savings, electrical energy savings and emission reductions to date are 3.4 GJ/t, 35 kW h/t and 212.54 kgCO 2 /t, respectively.

In recent years, there has been an increasing interest in waste heat recovery in the cement industry. The aim of this work is to determine the waste heat recovery by utilizing the waste exit gases from the pre-heater and grate cooler to generate electricity, furthermore estimation of cost saving. The results based on the operational data which is collected from Al-Muthanna Cement Plant. The net power output of 834.12 kJ/kg was estimated. A 6.673 ×103 MWh/yr electricity generation were achieved. The cost saving was estimated of 467,110.00 USD/yr in addition to 20 months was expected as the simple payback period.

The cement sub-sector consumes approximately 12-15% of total industrial energy use. Therefore, a state of art review on the energy use and savings is necessary to identify energy wastage so that necessary measures could be implemented to reduce energy consumption in this sub-sector. In this paper energy use at different sections of cement industries, specific energy consumption, types of energy use, details of cement manufacturing processes, various energy savings measures were reviewed and presented. Various energy savings measures were critically analyzed considering amount of energy that can be saved along with the implementation cost. Amount of CO 2 reduction has been presented along with the payback period for different energy savings measures as well. This study complied a comprehensive literature on the cement industries in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites. It has been observed that China producing major share of global cement production. Coal contribute major share of fuel used in cement industries. However, along with conventional fuels, industries are moving towards the use of alternative fuels to reduce environmental pollution. It was reported that cement industries are moving from wet process to dry process as it consume less energy compared to wet process.

The present article is dedicated for evaluating the power generation sub-sector in terms of energetic and exergetic aspects. In this regard, energy and exergy utilization efficiencies during the period 1989-2006 are assessed based on real data obtained from main generators in Jordan. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies for each of the studied power plant, and overall energy and exergy efficiencies for the entire sub-sector are found to be in the range of 31.95 to 35.99%. When compared with other neighbouring countries, such as Turkey and Saudi Arabia, the Jordanian power sub-sector is more efficient, but the opposite was noticed as compared with some developed countries, e.g. Norway and Malaysia, for year 2000. Such difference is inevitable due to dissimilar structure of the utility sector in these countries. It is expected that that the results of this study will be helpful in developing highly applicable and productive planning for future energy policies, especially for the power sub-sector.

Along with the enhancement of technology and alarming of global warming, various types of technologies are advanced worldwide nowadays to harness the energy from the sun such as solar thermal energy, ocean thermal energy conversion, solar ponds, solar tower and photovoltaic systems to utilize the energy in the majority of domestic applications and industrial sector to a certain extent. Subsequently, gradual increase usage of solar energy requires creating awareness among public to protect the environment in term of green campaign which is one of the hot topics among the Malaysians where there are many organizations organizing green campaign such as Environmental Protection Society Malaysia (EPSM), Malaysia Environment NGOs (MENGO) and Treat Every Environment Special Sdn. Bhd. (TRESS). Therefore, this study examines solar energy production and consumption worldwide by looking at various existing solar technologies to have the understanding of each technology. This article also intends to catch up specifically the social viability of solar energy production and use, with the availability of the resources for the full scale development.

Convective heat transfer of laminar forced convection in a wavy channel is studied in this paper. Numerical simulations of the 3D steady flow of Newtonian fluid and heat transfer characteristics are obtained by the finite element method. The effects of the Reynolds number (10 ≤ Re ≤ 1000), number of oscillations (0 ≤ N ≤ 5) and amplitude of the wall (0.05 ≤ A ≤ 0.2) on the heat transfer have been analyzed. The results show that the average Nusselt number is elevated as the Reynolds number is raised, showing high intensity of heat transfer, as a result of the intensified effects of the inertial and zones of recirculation close to the hot wavy wall. The rate of heat transfer increases about 0.28% with the rise of the number of oscillations. In the transfer of heat along a wavy surface, the number of oscillations and the wave amplitude are important factors. With an increment in the number of oscillations, the maximal value of the average velocity is elevated, and its minimal value occurs when the channel walls are straight. The impact of the wall amplitude on the average Nusselt number and dimensionless temperature tends to be stronger compared to the impact of the number of oscillations. An increase of the wall amplitude improves the rate of heat transfer about 0.91% when the Reynolds number is equal 100. In addition, when the Reynolds number is equal 500, the rate of heat transfer grows about 1.1% with the rising of the wall amplitude.

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Solar photovoltaic (PV) power generation is distinct from conventional power generation systems. It is vital to comprehend the effect of an expanded control system on solar PV generation. This article discusses the advancement made to the module, which is critical to PV and electric power systems, to achieve a high PV penetration in the smart grid system. The first zone initiates the solar power energizing transformation, which transfers a controlled energy load to a grid system. The descriptive subsections consider the accessibility of electronic inverters, solar PV energies, and grid concepts, as well as their realizability. As a result, a case study was considered, where various scientists around the world participated, discussion ensued, and future suggestions were made. Finally, practical conclusions were drawn from the investigations. This paper infers that the improvement of appropriate methods is fundamental to the viability and effectiveness of overseeing a high infiltratio...

Performance degradation of photovoltaic modules occurs when cell temperature increases; this is due to losses within the cell and the effect of surrounding weather as well. An increase in cell temperature leads to a decrease in the open-circuit voltage and hence, the electrical power produced by the PV. A nanofluid and nano-PCM (paraffin wax)-based PV/T hybrid collector has been employed in this paper. The experiments focus on the electrical performance and characteristics of the PV module under the weather conditions of Bangi-Malaysia. The cooling technique used is attaching the module to a nano-PCM tank and running nanofluids within. The results from the experimental tests show a maximum PV efficiency of 13.7% under operation for PV/T collector as appose to conventional PV module, which achieved an efficiency of 7.1%, which is suitable relative to the efficiency of 14% under standard testing conditions.

The study of flow and heat transfer around and through porous ribs is promising in many industrial applications that require high cooling rates, such as gas turbine blade cooling, or require noise reduction. Turbulent flow in porous media is usually investigated by using macroscopic transport equations, which are obtained by applying double (both volume and Reynolds) averaging to the Navier-Stokes equations. In this study turbulence is represented by using the Launder-Sharma low-Reynolds number k − ε turbulence model [1], which is modified via proposals by Nakayama and Kuwahara [2] and Pedras and de Lemos [3], for extra source terms in turbulent transport equations to account for the porous structure. Additional refinements are introduced to account for effects close to the porous media/clear fluid interface. In order to investigate the validity of the extended model, two types of porous channel flows have been considered, for which there is available DNS and experimental data. The first case is a fully developed turbulent porous channel flow, where the results are compared with DNS work conducted by Breugem et al. [4] and experimental work conducted by Suga et al. . The second case is a turbulent porous rib channel flow to understand the behaviour of flow through and around the porous rib, which is validated against experimental work carried out by Suga et al. [6]. Cases are simulated covering a range of porous properties, such as permeability and porosity. Through the comparisons with the available data, it has been found that the extended model shows generally satisfactory accuracy, except for some predictive weaknesses in regions of either impingement or adverse pressure gradients.

The study of flow and heat transfer around and through porous ribs is promising in many industrial applications that require high cooling rates, such as gas turbine blade cooling, or require noise reduction. Turbulent flow in porous media is usually investigated by using macroscopic transport equations, which are obtained by applying double (both volume and Reynolds) averaging to the Navier-Stokes equations. In this study turbulence is represented by using the Launder-Sharma low-Reynolds number k − ε turbulence model [1], which is modified via proposals by Nakayama and Kuwahara [2] and Pedras and de Lemos [3], for extra source terms in turbulent transport equations to account for the porous structure. Additional refinements are introduced to account for effects close to the porous media/clear fluid interface. In order to investigate the validity of the extended model, two types of porous channel flows have been considered, for which there is available DNS and experimental data. The first case is a fully developed turbulent porous channel flow, where the results are compared with DNS work conducted by Breugem et al. [4] and experimental work conducted by Suga et al. . The second case is a turbulent porous rib channel flow to understand the behaviour of flow through and around the porous rib, which is validated against experimental work carried out by Suga et al. [6]. Cases are simulated covering a range of porous properties, such as permeability and porosity. Through the comparisons with the available data, it has been found that the extended model shows generally satisfactory accuracy, except for some predictive weaknesses in regions of either impingement or adverse pressure gradients.

The RANS modelling of turbulence across fluid-porous interface regions within ribbed channels has been investigated by applying double (both volume and Reynolds) averaging to the Navier-Stokes equations. In this study turbulence is represented by using the Launder and Sharma (1974) low-Reynolds number k − ε turbulence model, modified via proposals by either Nakayama and Kuwahara (2008) or Pedras and de Lemos (2000), for extra source terms in turbulent transport equations to account for the porous structure. One important region of the flow, for modelling purposes, is the interface region between the porous medium and clear fluid regions. Here, corrections have been proposed to the above porous drag/source terms in the k and ε transport equations that are designed to account for the effective increase in porosity across a thin near-interface region of the porous medium, and which bring about significant improvements in predictive accuracy. These terms are based on proposals put forward by Kuwata and Suga (2013), for second-moment closures. Two types of porous channel flows have been considered. The first case is a fully developed turbulent porous channel flow, where the results are compared with DNS predictions obtained by Breugem et al. (2006) and experimental data produced by Suga et al. (2010). The second case is a turbulent solid/porous rib channel flow to examine the behaviour of flow through and around the solid/porous rib, which is validated against experimental work carried out by Suga et al. (2013). Cases are simulated covering a range of porous properties, such as permeability and porosity. Through the comparisons with the available data, it is demonstrated that the extended model proposed here shows generally satisfactory accuracy, except for some predictive weaknesses in regions of either impingement or adverse pressure gradients, associated with the underlying eddy-viscosity turbulence model formulation.

The study of flow and heat transfer around and through porous ribs is promising in many industrial applications that require high cooling rates, such as gas turbine blade cooling, or require noise reduction. Turbulent flow in porous media is usually investigated by using macroscopic transport equations, which are obtained by applying double (both volume and Reynolds) averaging to the Navier-Stokes equations. In this study turbulence is represented by using the Launder-Sharma low-Reynolds number k − ε turbulence model [1], which is modified via proposals by Nakayama and Kuwahara [2] and Pedras and de Lemos [3], for extra source terms in turbulent transport equations to account for the porous structure. Additional refinements are introduced to account for effects close to the porous media/clear fluid interface. In order to investigate the validity of the extended model, two types of porous channel flows have been considered, for which there is available DNS and experimental data. The ...

The increase in  using the composite materials in engineering applications make it necessary to improve the properties of composite materials to be able doing its work . One of the method to improve the mechanical properties for fibrous composite materials is Pre-stressing the fibers during room temperature curing process . This process give the more stiffness for composite and make it more stronger and able to withstand the loading subjected to it . This paper show that the pre-stressing fiber process on the glass fiber/epoxy composite materials will give the more strength and make the composite able to carry larger load . The pre-stressing fibers level will be  ( 0 , 2 , 4, 6, 8, 10 , 15 , and 20MPa) that applied on the E-glass fibers with epoxy resin during the curing process with fiber volume fraction about (30%) , and after solidification complete the samples tested under tensile loading by using INISTRON machine  . The results show the improvement in tensile strengths reach to(70%) at pre-stressing level (20MPa) while the increasing in maximum tensile strain reach to( 46%) . The modeling of composite samples subjected to tensile load by using finite element method with package (ANSYS V.10) . 
The relation between pre-stress levels and maximum deformation  at different external loading between (1kN to 4.5kN) for composite sample were plotted for experimental and finite element results . The differences between experimental and ANSYS results was about (6-12%).

The buckling strength of slender columns its important property especially for columns that subjected to axial compressive forces. In this paper, we study the effect of cooling rate after heating over (Ac3) for martensitic stainless steel columns on the buckling strength and elastic properties for different type of fixing for column. The results show that the best buckling strength occurs when using very slow cooling rate (inside furnace), that the buckling strength increased about (31%) and elastic modulus increased about (25%) because the slow cooling increase the formation of pearlitetic microstructure that had high strength and good elastic properties . The very fast cooling rate (in salt water) decreased the buckling strength about (46%) and elastic modulus about (51%) because the fast cooling rate increase the formation of martensitic microstructure that had high hardness and low buckling strength and low elastic properties.

he welding process is one of the oldest joining processes between the materials, this paper try to find the effect of welding joint location in the steel on the fatigue strength of steel.
The welding process done by electrical arc welding to joining steel samples at different locations at (X/L=0.25, X/L=0.5, and X/L=0.75), where (X) the location of welding zone centre  and sample subjected to fully reversed bending stress, then comparing the fatigue test results with un-welded sample. The experimental results show that the welding joint decrease the tensile strength of steel and the fatigue failure strength also decreased specially for that with (X/L=0.5 and X/L=0.75) and failure occur at welding zone, but the sample with (X/L=0.25) had less effected by welding joint and the failure occur at the support not at welding zone. The results show fatigue life affected by the welding joint when draw (S-N) diagram for each sample especially for sample with (X/L=0.5 and X/L=0.75).  Keywords: welding of steel, fatigue, S-N diagram, finite element analysis, fatigue behavior of steel weldment.

he fatigue failure is the reason of (90%) of mechanical failures. This work tries improving the fatigue strength and increasing the fatigue life for steel bars that used in concrete reinforcing. Tensile test were done to find the mechanical properties of steel bar. The heating over critical temperature (AC3) and cooling by different cooling rates were done for steel bars, and tested this samples by tensile and fatigue tests. The tensile test results show increasing in yield and tensile strength for sample that cooled by oil (medium cooling rate).The  fatigue test results show increasing in the fatigue life for samples that cooled by oil.