Abstract: Nowadays, microelectronics plays a key role in our daily lives, such as communication, transportation, embedded systems, medicine etc, so we need to make sure that we can rely on microelectronics systems, while considering the thermal and vibratory fatigue, to make sure of that a lot of methods and simulation were introduced into the process of manufacturing. The reliability and fatigue life prediction of a system is an important problem in product design field, These problems are caused by the fatal flaw of the microelectronic packaging which contain solder joints, their reliability has a great impact on the reliability of the entire packaging structure. The cause of the fatigue failure of solder joints is usually caused by the accumulation of thermo-mechanical damages due to the operating conditions of thermal and mechanical shock. To predict the fatigue life of solder joints in ball grid array (BGA) packaging, finite element analysis methods are mostly used but this tool is not enough since they are based on a deterministic approach; the variability of the input parameters are neglected by this approach, which has an impact on the output of the model. Thus, we need to use a probabilistic approach. In this paper, we focused on the major factor of failure for solder joints as known as thermal fatigue. A finite element analysis using ANSYS 15.0.1 APDL was used to predict the fatigue life of the most critical solder joint under thermal cycle loading. The failure probability of the most critical solder joint of the microelectronic packaging is defined using two methods of numerical study of probabilistic methods which are: The First Order Reliability Method (FORM) and Monte Carlo Simulation (MCS).

Abstract: The past few years have observed a fast increase in the popularity of 3D printing technology, e.g., for rapid prototyping. Additive manufacturing (AM) represents a spectrum of technology producing 3D printed parts layer-by-layer or even path-by-path. The aim of this paper is to study and minimize the warping deformation of open source FDM 3D prints focusing on the different process parameters. More precisely, this paper tackles the influence of the different nozzle temperatures ranging from 180°C to 220°C and printing speeds ranging from 5 mm/s to 20 mm/s on the FDM 3D components during the printing process. The process involved FDM 3D solid modeling as regards design, FDM 3D printing with PLA+ filament material with flat 45°/-45° build orientation, warping deformation measurement and statistical analysis. The experiment produced the minimum result of warping deformation value that can be achieved when the nozzle temperature was 220°C by reaching 2.0% error at corner 1 (starting point) and 4.55% overall error for FDM 3D printed part 1 (15 mm/s printing speed) when using coated thermos adhesive applied to the printing platform. It also shows that less than 1% error can be reached when 20 mm/s printing speed and 220°C nozzle temperature is selected.

Abstract: In this work, natural rubber (NR) composites filled with gelatin starch (GS) were successfully prepared through compression molding using tetramethyl thiuram disulfide (TMTD) as a catalyst. The FTIR results revealed that the reaction of GS with NR surface occurred to confirm the GS grafting NR. The peaks of −OH bending in the range of 1369–1459 cm−1 disappeared in GS. The SEM of B1, B2, B3 and B4 blends showed weak adhesion between NR and GS interface. The tensile strength and elongation at break gradually reduced with adding of GS while the tensile modulus at 100%, 200%, and 300% elongations increased up to optimum loading (50 phr GS). The delta-torque, maximum torque, cure rate index and scorch time increased at loading of GS while the curing times (t90) decreased with the increase of GS loading. It was concluded the GS behaves as a co-agent of TMTD accelerator for curing process.

Abstract: In this paper to increase the maneuverability and lateral stability of a vehicle a new control system is proposed. First a fourteen-degrees-of-freedom nonlinear dynamic model of a four-wheeled vehicle is developed. Then the vehicle model is validated using real test data and ADAMS CAR software during different maneuvers. Next to improve the vehicle dynamic performance, a new control system designed based on a simplified dynamic model. Also, the control system performance is evaluated at different velocities. Simulation results show that the controller improves the vehicle’s handling, especially during severe slalom maneuver in which intense instability occurs. Moreover, the proposed control system is robust against variations in the parameters and in the velocity of the vehicle.

Abstract: Energy efficiency in buildings and the thermal insulation of the envelopes are a field of research is very important and have experienced a great development in recent years. In addition, several research are very interested in the use of new biobased materials to improve the thermal insulation in the building. The plant fibers are more and more used as reinforcement in the construction materials while maintaining levels of mechanical performance sufficient. Among these fibers; the fibers of alfa (Stipa tenacissima L) who is a member of the GRASS family (Macrochloa Tenacissima). The operation of this plant is an appropriate subject. It is in this perspective that fits our work. In effect, an experimental study was conducted to determine the effect of adding fiber of Alfa considered additive on the thermal properties of the plaster taken as the matrix. In a first time, experiments to determine the thermal properties by the method of the boxes using the device EI700 have been carried out after drying through the method of weight loss. Then, an individual house has been modeled under TRNSYS to determine the influence of our material on the charges for heating and air conditioning. The results obtained show that an increase in the percentage of alfa leads to a significant reduction in the thermal conductivity of the composite and then a reduction of up to 15% in the energy requirement of the building.

Abstract: Trajectory planning is the most crucial part in robot design especially for exoskeleton robot. The suitable trajectory will directly affect safety, health, and comfort of the wearer. In trajectory generation profile of lower limb exoskeleton robot, the cubic polynomial is commonly used to generate smooth trajectory generation profile. Whereas, the quintic polynomial is not widely used due to complexity. This paper aims to make comparative studies between cubic and quintic polynomials. Whereas, the accuracy of generated profile will be investigated and analyzed to understand the gap of knowledge. Based on that, the gait cycle motion is divided into seven sub-phases. Each sub-phase is presented by one polynomial equation either cubic or quintic. Accuracy analysis was involved in order to show either cubic or quintic polynomial is accurately matched to human walking motion profile. The result shows that quintic generates an accurate profile motion of ankle, knee, and hip joints with 0.48520,0.42830, 0.39170 RMS error respectively. Meanwhile, cubic polynomial generates the trajectory motion profile of ankle, knee, hip joints with 0.84170, 0.97280, 0.26390 RMS error respectively. Thus, the quintic polynomial is more accurate than cubic polynomial to generate trajectory profile with the smooth transition.

Abstract: The growth of innovative renewable energy sources is a worldwide consideration due to the high power demand and the harmful influence of conventional sources of energy to the environment. Besides the solar and wind energy, fitness facilities around the world employed the cardiovascular machines such as elliptical trainer to generate energy throughout the exercise. As a further utilization of the gymnasium’s machines, the proposed project developed a green weight-lifting machine with high torque generator and gears-shifting mechanism to generate electricity during the user’s workout. The mechanical design of the machine focused in altering the linear motion by the user to rotational motion via pulleys and wheel, which then converted by the generator to electricity. The power stabilization system was also introduced to amplify and stable the generator’s output power with the help of capacitor, voltage converters, and Arduino controller. Each gear level in the gears-shifting mechanism represents specific kilograms to be lifted, which were theoretically derived and then compared with the testing results where 96.7% accuracy was successfully achieved. The conducted six tests were designed to find out the lifted kilograms and generated power in four exercises with six levels of gears.

Abstract: Jet impingement is one of the best methods for achieving high heat-transfer coefficient over a flat plate surface. It has been an active research topic for several decades [1]. This study performed experiments on various parameters, such as nozzle-to-nozzle spacing (S/d = 1, 2, and 3 cm) and the distance between the nozzle and the aluminum plate (H/d = 1, 6, and 11 cm), to determine the effect of different Reynolds (Re) numbers using the twin jet impingement mechanism on the local heat transfer of an impinged flat aluminum plate. The same setup was used to measure the heat flux of the jet impinging on a flat aluminum plate surface. The heat flux of the heated air jet impinging on the plate was measured using a heat flux micro-sensor at radial positions 0–14 cm away from the stagnation point. The measurement of the heat flux was used to calculate the local heat-transfer coefficient and local Nusselt (Nu) number for steady air jet and air jet impingement. The Re used were 17,000, 13,000. Results show that the local Nu number was calculated at all measurement points. Furthermore, the Nu number increases with the Re number in the steady jet. The relationship between the results shows that higher flow velocity results in the higher localized heat flux of the steadily heated air jet impinging on the aluminum plate. In addition, the best heat-transfer coefficient in the area near the nozzles and aluminum plate and the nearest distance between the nozzles, especially in the first five points at the plate, decrease away from the center of the aluminum plate for all Re numbers used. Thermal data were collected by Graphtec GL820 multichannel data logger and Fluke Ti25 to capture the temperature distribution in front of the aluminum foil.

Abstract: Three floors building model made from carbon steel was tested in the current work to show its vibrational behavior under transient excitation. The main contribution of the current work is to show the effect on adding vibrational damper in first floor with numerous orientations on the vibrational modes, then studying the effect of adding second set of dampers on the second floor. Numerical and experimental analyses were carried out on the tested model for both modal and transient analysis. Results show that the adding of vibrational damper will boost the ability of the tested structure to withstand against all modes of vibrations for all selected damper's orientation. Best enhancement in the vibrational modes of the tested structure was satisfied with adding double vibrational damper the orientation of 45˚ at first and second floor respectively.

Abstract: In the current study, the effect of adding nano Al2O3 to 3 mol%Y2O3 stabilized tetragonal zirconia (3Y-TZP) prepared by precipitation method on the grain size and the mechanical properties was investigated. Different amount of nano Al2O3 (1.5 wt. % , 2.5 wt.% , 3.5 wt.% and 4.5 wt.%) have been added to (3Y-TZP). X-Ray diffraction (XRD) and scanning electron microscopy (SEM) was used to characterize both the prepared powder and the full dense ceramic composite. It has been found that ,the addition of nano Al2O3 have an influence on the densification process and lead to increase in both the apparent and bulk relative densities and recorded a 96.45% and 94.46 % respectively at 4.5 wt.%. The results also shows a decrease in grain size from 0.7 µm to 0.62 µm as the amount of nano Al2O3 vary from 0 wt.% to 4.5 wt.% due to the restricted of the grain boundary mobility via the effect of particle pinning. Also, the addition of nano Al2O3 have great effect on mechanical properties .The Vicker's microhardness and the flexural strength shown an increase as the nano Al2O3 amount increase and recorded 1028.48 HV, and 368.62 MPa maximum values respectively at 4.5 wt.% nano Al2O3 .

Abstract: This work aims to obtain an optimal shape of the Syme prosthesis cut-out in addition to deciding the type of composite material and number of layers to be used in the manufacturing a Syme prosthesis of high strength as compared to the conventions polypropylene type. To achieve this aim, an experimental program was conducted using two systems of stacking sequence (2 Perlon fiber + 1 Carbon fiber + 2 Perlon fiber + 1 Carbon fiber + 2 Perlon fiber) and (2 Perlon fiber + 1 Carbon fiber + 1 Perlon fiber + 2 Carbon fiber + 1 Perlon fiber + 1 Carbon fiber + 2 Perlon fiber). In order to decide, the cut-out shape, a theoretical examination was achieved, where four shapes were tested (elliptical, θ= 180°, θ= 210° and θ= 270°) and analyzed by the SOLIDWORKS program. The determination of pressure distribution was measured by using the F-Socket device. The results showed that by increasing number of carbon and perlon fiber layers, the strength is increased, system two showed better results where it leads to decrease the maximum stress, maximum deflection and Von Mises stress by 37.7%, 97.6 %, and 25% respectively as compared to polypropylene socket. The results indicate that the elliptical shape of socket cut-out is recommended to be used in manufacturing the prostheses, where the maximum stress, maximum deflection, and Von Mises stress were reduced by 50%, 30 %, and 44% respectively as compared to the socket with θ= 210° Cut-Out (Old socket).