Fused deposition modeling (FDM) is one of the most additive manufacturing techniques that adopted to produce prototypes and/or final parts, particularly under geometrical complexity restrictions. One of the most challenging aspects of FDM technology is the attainable roughness. In this paper, a hot-air jet was applied simultaneously during the printing process of FDM products to investigate the effect of its factors on surface roughness. Experimentally, a test rig was utilized to evaluate the effect of these factors on surface roughness. Two main factors were addressed: air jet temperature; and nozzle translational velocity over the part surface and investigated their effect on the roughness. Statistically, ANOVA and regression analysis were conducted to study the contribution of the individual factors to the process response and to introduce regression model to predict the resulting surface roughness in terms of different …

The large number of interdigitated electrodes (IDEs) in a macro fiber composite (MFC) piezoelectric actuator dictates using a very fine finite element (FE) mesh that requires extremely large computational costs, especially with a large number of actuators. The situation becomes infeasible if repeated finite element simulations are required, as in control tasks. In this paper, an efficient technique is proposed for modeling MFC using a finite element method. The proposed technique replaces the MFC actuator with an equivalent simple monolithic piezoceramic actuator using two electrodes only, which dramatically reduces the computational costs. The proposed technique was proven theoretically since it generates the same electric field, strain, and displacement as the physical MFC. Then, it was validated with the detailed FE model using the actual number of IDEs, as well as with experimental tests using triaxial rosette strain gauges. The computational costs for the simplified model compared with the detailed model were dramatically reduced by about 74% for memory usage, 99% for result file size, and 98.6% for computational time. Furthermore, the experimental results successfully verified the proposed technique with good consistency. To show the effectiveness of the proposed technique, it was used to simulate a morphing wing covered almost entirely by MFCs with low computational cost

In rural and remote areas, solar photovoltaic energy (PV) water pumping systems (SPWPSs) are being favored over diesel-powered water pumping due to environmental and economic considerations. PV is a clean source of electric energy offering low operational and maintenance cost. However, the direct-coupled SPWPS requires inventive solutions to improve the system’s efficiency under solar power variations while producing the required amount of pumped water concurrently. This paper introduces a new quadratic V/f (Q V/f) control method to drive an induction motor powered directly from a solar PV source using a two-stage power converter without storage batteries. Conventional controllers usually employ linear V/f control, where the reference motor speed is derived from the PV input power and the dc-link voltage error using a simple proportional–integral (PI) controller. The proposed Q V/f-based system is compared with the conventional linear V/f control using a simulation case study under different operating conditions. The proposed controller expectedly enhances the system output power and efficiency, particularly under low levels of solar irradiance. Some alternative controllers rather than the simple PI controller are also investigated in an attempt to improve the system dynamics as well as the water flow output. An experimental prototype system is used to validate the proposed Q V/f under diverse operating conditions.

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In this experimental and statistical investigation, Silver (Ag) nanoparticles with varying particle sizes of 20 nm with the base fluid of EG and DI water are tested to improve the heat transfer properties of the car radiator. The thermophysical properties are tested at temperatures varying from 35 to 75
C. Results showed that small nanoparticles had higher thermophysical properties than large nanoparticles. The heat transfer properties along with friction factor characteristics are measured. A total of 20 nm of Ag has higher thermal transfer properties than other nanofluids; it can be concluded that smaller nanoparticles can improve thermal properties and minimize the radiator size compared to traditional coolants. A systematic optimized RSM-based architecture has been developed to define the quantitative estimate of the specific design parameters influencing nanofluid heat transfer properties and friction factor characteristics. Finally, correlations are developed for experimental Nusselt number and friction factor values by regression analysis.

Post-quantum cryptography is an emerging solution to the expected security breach, introduced by quantum computers, to the currently used public key cryptosystems. This paper presents an experimental study on the effect of the overhead associated with the wireless transmission of some of the newly developed post quantum cryptography algorithms through the Internet of Things networks. Experimental results of this work include the energy and time measurements for wireless transmission of chosen sample messages of these new cryptographic algorithms. In addition, recommendations are given for appropriate modules configurations and choice of suitable security algorithm for the Internet of Things networks.

In this paper, we present an Internet of Things framework for structural health monitoring. The proposed system detects the delimitation and debonding in composite concrete structures: more specifically, develop an IoT-Based Non-Destructive Test (NDT) to detect debonding between Carbon Fiber sheets and Concrete slabs. An Inter Digital Capacitance Sensor is designed and fabricated to function as the primary detection element. The sensor is embedded within an IoT node that manages the measurement process, captures the measurement location automatically, and performs essential data filtering operations with an attached graphical interface that allows basic control and early-access to the measured data. The IoT node integrates within the larger framework via wireless WiFi connection throughout which the data is transferred and control functions are administrated. The paper presents the system design details including mathematical modeling for the capacitance sensing element, finite element simulation results, and practical setup measured data.

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 %.

This paper presents a non-destructive capacitance-based technique for rebars detection in reinforced concrete structure. The proposed technique depends on capacitance variation between the two electrodes of a co-planar capacitive sensor while scanning across different concrete sections with and without reinforcement bars. A mathematical model is used to provide meaningful interpretation for the effect of different sensor and concrete parameters on the measured capacitance. The finite element model is built and accompanied by a dedicated experimental setup to confirm theoretical estimations. Simulation and experimental results confirmed a detectable capacitance variation while scanning across the reinforced concrete slab in experimental setup for rebars detection.