Abstract: The present study attempted to establish a prediction model for the hardness and mechanical properties of Cr-Ni-Mo steel by quantifying the hardenability of 34CrNiMo6M steel, which is used for the main shafts of large wind power generators with capacities of at least 4 MW, by means of a large Jominy specimen. A large cold specimen was fabricated by normalization after forging, and a cooling experiment was performed by using a special Jominy testing device for high weight ratios. As the Jominy test measures hardenability, the hardenability of a heavy main shaft was quantified, and the mechanical properties of the large forged product were examined according to depth. In addition, the hardness of the forged product by location was predicted by using experimental data and an analysis method. Cooling curves for different measuring points were input in a Jominy test considering the mass effect. In this way, the structure, strength, and hardness at various depths could be predicted. After cooling curves over time at each position were calculated by means of DEFORM, the hardness, strength, and the fractions of components were calculated by applying the Quench property module of JmatPro. The results obtained by using JmatPro sufficiently matched the experimental hardness results and the observations by an optical microscope.

Abstract: This paper presents the CFD study of the aerodynamic structure in an indoor environment occupied by a human body. Reynolds Averaged Navier-Stokes equations were used and different turbulence models were evaluated such as the RNG k-ε turbulence model, the standard k-ε turbulence model, the standard k-ω turbulence model and the SST k-ω turbulence model. The results of our simulations developed using the software ''ANSYS Fluent 17.0'' were compared with findings from anterior experimental measurements. This comparison affirms that the turbulence model has a direct effect on the aerodynamic structure in an indoor environment. In fact, the SST k-ω turbulence model presents a good agreement with the anterior study and it is recommended for the related type of application. These numerical results highlight a thermal plume above the human body due to the convection heat transfer. Finally, indoor thermal comfort analyses are conducted at varying supply velocity

Abstract: The aim of this work is to investigate numerically the influence of layer thickness and wavy interface wall on the heat transfer and fluid flow inside a differentially heated square enclosure occupied with two portions, Ag/water nanofluid-porous medium and non-Newtonian substance, respectively. The numerical computations have been carried out for Rayleigh number Ra= 103 to 105, number of undulation N= 1 to 4 (four cases) Darcy number Da= 10-1 to 10-5, volume fraction ϕ= 0 to 0.2 non-Newtonian index n= 0.6 to 1.4 and the Prandtl number of water Pr= 6.2, for different interface location S=0.25, 0.5 and 0.75. The governing equations were solved numerically by using finite element techniques based Glarkine approach solver to take out an expression of streamlines and isotherms. The output results were compared with previous work and it was observed that a good formal equivalent between the results. Results demonstrated that as power law index "n" increases the average Nusselt number decreases due to high viscosity and shear force of pseudoplastic fluid. Consequently, layer thickness has a major impact while the number of undulation has a a minor impact on the heat transfer rate across the layers.

Abstract: This paper presents a denture fabrication process by implementing the techniques used in the addictive manufacturing which is 3D printing technology involving reverse engineering method. A three dimensional scanner was used to obtain the surface data of the complete partial denture model that received from the dental clinic. The scanned data was refined using the Geomagic Studio and then converted to STL format for CAD and 3D printing application. The complete dentures design was converted to STL format for production of the product using the Projet HD 1000 machine which is one of the rapid prototyping (RP) technique. Cold cure acrylic resin (VERTEX, Castavaria) was used as the denture material on the gum section. On the teeth section, the composite resin will be applied to add an aesthetic value to the part. Then, the final dentures were polished and tested on an edentulous model to test the bite and adaptability. The finished denture has been test to ensure the adaptability and comfortability. Thus, the user felt comfort while tested the printed denture. The method of fabrication by addictive manufacturing is much faster compared to traditional method. The time taken to complete the denture is 5 hours. Otherwise by conventional method consumed about 15 hours. The result for the denture has been checked to ensure satisfactory and good accuracy. Unlike the traditional method of fabrication, this research has potential to reduce fabrication period of time and make it easier to replace a new set of denture that had been broken.

Abstract: -- In order to reduce the leakage in turbo machines, the straight labyrinth seals are used. Problems may happen in modern turbo-machines due to the unstable working conditions. This type of motion can occur when the labyrinth seals do not respond in a good manner for rotor dynamics and tangential force that act on the rotor in the whirl direction. So, the accurate predictions of dynamic behavior for labyrinth seal are very important to optimize the stability of the system. The bulk-flow model based on a computer code written in Fortran 90 has been used in this work. This research explains the effect of seal geometry (clearance and tooth angle) on rotodynamic coefficients which are dynamic and stiffness coefficients for seal with grooves on rotor and stator. These coefficients are calculated at three values of tooth angle (00, 200 , and 400) and three values of clearance (0.33, 0.4, and 0.5) at whirl frequency ratio of . The analysis of stability of the rotor system depends on the stiffness and damping coefficients. The resulted parameter from stiffness and damping coefficients is a tangential force, that can be considered as an indication of the system stability. It can be seen from the results that the increasing of stability of the system increased with increasing the clearance and tooth angle, that can be attributed to the decreasing of the cross coupled stiffness and damping coefficients and increasing of direct stiffness. In this study, a comparison was made between the stability of labyrinth seals when teeth fixed on the rotor with the other type when teeth are fixed on the stator . The results showed that the labyrinrh seal with (TOR) was more stabile than seal with teeth on on the stator. The main benefit that achieved by the research results can be illustrated by two sides. The first side, the research results explained that the analytical methods, when applied correctly can solve the problems of the stability of the rotor system that occurs in most of turbo machines. On the other hand, the results have shown that it is possible to reduce the leakage of fluids and the unstable movement of rotary systems through the use of labyrinth seals designed with teeth attached to the rotor of labyrinth seal.

Abstract: Chemical mechanical polishing/planarization (CMP) process is a primary wafer and thin film planarization process for semiconductor fabrication. In CMP process, a diamond dresser with well-distributed diamond grits is usually applied to regenerate the surface topography of polishing pad for maintaining the wafer material removal rate (MMR). This paper aims to develop a model of reaction force on quasi-orthogonal machining by a pyramid single-diamond tool on a soft elastomer pad. Forces have been analyzed under two dressing conditions which are face dressing direction (FDD) and edge dressing direction (EDD). The reaction force model for the pad has been investigated considering geometry of diamond grit and contact areas between the diamond grit and the pad surface. The reaction force profile obtained by experiment agrees with a simulation of normal reaction forces. Results of this study can be applied to predict diamond wear rate for diamond dressing process. Furthermore it can be extended to design diamond dresser for optimum pad cutting rate (PCR) during dressing process for semiconductor fabrication.

Abstract: This research work is focused on the numerical study regarding Carreau nanofluids’ squeezed flow via a permeable sensor surface. The nanofluids’ thermal conductivity is considered to be dependent on temperature. A convenient transformation is employed to reorganize governing equations into ordinary differential equations. The Runge–Kutta method and shooting technique are employed to accurately solve the boundary layer momentum as well as heat equations. Graphical and tabular aids are used to evaluate the solutions of applicable parameter with regards to temperature as well as the rate of heat transfer. In this work, a comparison is done from three nanofluids, i.e. copper, oxide aluminum and SWCNTs (nanoparticles) based fluids (water, crude oil and ethylene glycol) to improve heat transfer. It is found that the temperature dimensionless was dropped and dominated with the squeezed flow parameter and nanoparticle volume fraction parameter. That is for all nanomaterials. When compared with water and ethylene glycol, crude oil is cooler and a thinner thermal boundary layer is presented. For the rate of heat transfer (Nusselt number) was higher in: Ethylene glycol- SWCNT with high permeable velocity parameter 0.2, Ethylene glycol- SWCNT with low squeeze flow parameter 0.1 and Ethylene glycol- oxide aluminum with low nanoparticle volume fraction 0.05

Abstract: This paper presents a hybrid control model, which is based on the Real-Time Unified Modeling Language (UML) and hybrid automata in order to conveniently analyze, design and implement industrial Hybrid Dynamic Systems (HDS). This model also creates a communication pattern, which can permit the designed components to be customized and reused in new control applications for various HDS types. The paper shows out step-by-step the specification of an industrial HDS modeled by the specialization of hybrid automata, the analysis and design of HDS controllers by using the Real-Time UML, which allow us to quickly find out the main control capsules, their ports and communication protocols in order to precisely model and tightly allocate control structures and dynamic behaviors for the implementation of industrial HDS. Following this proposed model, the application to KC05.21/16-20 project entitled “Research, design and manufacture geothermal cooling systems for Base Transceiver Station” is finally presented.

Abstract: forced convection boiling heat transfer in vertical tube filled by metal foam for Refrigerant(R-134a) (the working fluid was used because it is zero ozone depletion) is numerically investigated using the modified multiphase mixture model for various heat flux. The effect of changing mass flux, porosity and PPI was analysed. It was found that, both of pressure drop and heat transfer increase as mass flux increased and higher values are obtained with higher PPI and lower porosity. Vapour dryness reaches its maximum value at the exit (about 30%) with higher PPI, lower porosity, and low mass flux. Results also show that the local Nusselt number increases more rapidly along the heated wall when heat flux increased which leads to form a two-phase zone adjacent to the heated wall, while the average Nusselt number increases as mass flux increases for constant heat flux value and will be higher for high PPI metal foam.

Abstract: There are enough corroded steel structures, which is used in urban areas. As a result of the impact, these structural elements have begun to corrode and their operational suitability has to be checked. Corrosion impact studies on mechanical properties are sufficient in number, but there is still no definitive formula for calculating Ultimate strength and Strain. Ways should be sought to create a single equation that can be evaluated as quickly as possible with practical accuracy, as a result of corrosion, which real values are to be expected. This helps in the preliminary analysis to determine the degree of operational suitability of the steel load-bearing capacity, respectively to plan the necessary repairs and possibly to foresee at what point in time the structure will fall into an emergency state due to the corrosion effect. The negative influence of the corrosion on the steel elements has been found, mainly consisting of a reduction of the geometrical characteristics, superficial defects, a change in the structure of the material, including a change in the stress-strain diagram, i.e. the ductile material steel becomes a brittle material. I made a study and collected experimental data from corrosion influence on S355JR construction steel. I processed the results using the stochastic method and the average method. From the values obtained, I plotted the chart. I applied the polynomial approximation of establish graphs and found dependence on nonlinear equation. The equation I came to can be taken as a general equation, but the coefficients should be different depending on the corrosion resistance of steel.

Abstract: This paper presents a driver's good postures correction model while driving for smart vehicle seat using multinomial logistic regression. The good driver’s seating postures are considered the angles for the placement of human body, the space for foot controls in vehicles, and the ranges of adjustments of the driver's seat and steering wheel. According to them, for the good postures, it has adjusted seat height, seat angle, head height, back of knees, distances of foot pedals, tilt of seat, etc. for each driver. There have been some studies on analysis for comfort vehicle driver’s seat, analysis of interface pressure of drivers, correction of good posture, effects of driving environment on the posture, and sitting strategies with seating pressure distribution. However, there are a few studies on correction model for driver’s good postures while driving using machine learning. Therefore, we suggest 1) a driver's good postures while driving in vehicle and 2) a good postures correction model for them using multinomial logistic regression. We developed the system with the Arduino board and C-type piezoelectric effect elements to get driver’s postures while driving. For the experiments using the logistic regression models, first, we collected the piezoelectric values from 55 drivers and 17 types of cars from the system, second, defined the 6 types of good postures with thresholds, and third, analyzed the postures from test data using multinomial logistic regression for the types using them. As the results, it can apply with a smart vehicle seat system and can guide the good postures correction for the bad postures while driving in real-time.

Abstract: In this paper, passive and semi- active suspensions system of a magnetorheological fluid damper for an automobile application under different excitations (step, sinusoidal, and random) as road profiles is studied. This work is presented in two parts, the dynamic responses of the MR fluid damper under the expiation are presented in the first part and developing a simple and efficient controller to control the damper behavior is presented in the second one. Bingham plastic model is adopted for the mathematical modeling and analyze the hysteretic behavior of the MR fluid damper. LQR algorithm is used for the control processes. The results showed that the input current to the magnetic circuit plays an important role regarding the dynamic response and damping force for the excitation, however, current effect is different for the excitations. Magnetic saturation is noticed in the dynamic response. Damping force can be controlled by controlling the input current to reduce the overshoot, steady-state error, and steady state time response. In addition, the linear quadratic regulator (LQR) has successfully stabilized the system and removes the vibration without any abnormal behavior.

Abstract: Many heating or cooling-based engineering and industrial application use impinging jets, due to their higher convective heat transfer coefficient values. Here, the researchers stated that there was less available information regarding an increase in the heat transfer rates, when twin impingement jets were placed horizontally, at a distance from the stagnation point. Some studies made use of a twin impingement jet process for numerically and experimentally increasing the heat transfer values. In this study, the researchers carried out a numerical simulation that was based on an RNG k-ε turbulence model, in order to determine the cooling process for the heated surface of an aluminium plate. For this purpose, they used a Twin Jet Impingement Mechanism (TJIM), which consisted of 9 models. Furthermore, they also studied the effects of the nozzle-nozzle distances, nozzle-plate distances and Re number of the convection heat transfer for calculating the heat transfer coefficient, Nu number and a thermal enhancement factor. Some of the main conclusions observed in the simulation study were further used for validating all the experimental results and determining all major parameters that could affect the heat transfer rate, Nu number and distribution of the static pressure. The arrangements of all jets showed that Model 1 was ideal for calculating the Nu number when S/D= H/D=0.5. Meanwhile, Model 9 displayed the worst results, where S/D= 1.5 and H/D= 5.5. The results also showed that an irregular distribution of a local Nu number (Nu) on the impinged surface occurred due to a decrease or increase of the flow turbulence. Various twin jet arrangements showed that Model 9 displayed the worst results, where S/D= 1.5 and H/D= 5.5. All numerical results were validated after comparing the simulation and experimental results for the TJIM. This further described the temperature distribution on a flat metal surface for different models. Here, the researchers have calculated the enhancement factor using different nozzle arrangements in 9 models. This value ranged from 6.4% and 24.3%, in the case of simulation studies, whereas in the actual experiments, it ranged from 5.3% to 37.9%. The simulation model showed a 12-41% increase in the average heat transfer rate for the complete aluminium plate. Based on the validation model, the experimental and numerical tests indicated an 8.5% error percentage. Hypothesis: Nusselt number and heat transfer coefficient were impacted by the spacing between nozzles and the distance between nozzle and plates. Characteristics of heat transfer could be enhanced if the researchers selected an appropriate impingement mechanism and selected the optimal levels of other factors.