Composite material applications in the aerostructure manufacturing industry are rapidly increasing. These aerostructures can be monolithic, e.g., A350 Inboard Flaps, or sandwich structures, e.g., A330 spoilers. Curing composite structures in the autoclave generates residual stresses that lead to dimensional infidelity known as Process-induced Deformations (PIDs) due to stress relaxation after structure demoulding. These stresses arise in composite structures mainly due to the anisotropy nature of the composite material, and the tool-part interaction. PIDs are a concern in the assembly stage of the final composite structure when they are not accounted for in the design phase. They can be predicted experimentally or by simulation using ABAQUS/ COMPRO simulation tools. This paper discusses PIDs simulation results using validated FE models for two commonly used composite structures in the aerospace industry; monolithic and sandwich structures. PID was predicted with high accuracy (Error < 20%), and the residual stresses were discussed as well.
This paper presents analog circuit for signal processing of biosignals using wavelet transform. The proposed 7th-order OTA-C band pass filter provides programmable gain ranging from -7.65 dB to 23.2 dB, and tunable center frequency from 0.162 Hz to 101 Hz. The filter topology is based on an OTA-C structure providing a Balanced-Input Balanced-Output (BIBO) filter realization with grounded capacitors. The filter is simulated in LTspice using 90 nm CMOS technology providing a dynamic range of 55.9 dB and low power consumption of 1.02 nW.
This work explores the effects of linear proportional integral and nonlinear fractionalorder (FO) proportional integral (PI) control strategies on an electric vehicle traction system. A 400 V, 6.6 Ah Li-ion battery bank is established to power an indirect field-oriented controlled prototype electric vehicle drivetrain. In contrast to integer-order (IO) PI controllers, the nonlinear nature of fractional-order PI controller provides immunity to induction motor parameters variation and external disturbances. The appeal of this paper is to reveal the simplicity, robustness, and effectiveness of fractional-order PI speed regulator for electric vehicle traction system. The efficacy of FO-PI speed regulator for the electric vehicle applications is validated through experimentation.
In this work, universal adaptive stabilizer (UAS) based particle swarm optimization strategy is developed for accurate identification of Li-ion battery model parameters. Among various battery parameters estimation techniques, UAS based adaptive parameters estimation (APE) strategies have an advantage of estimating battery model parameters within few computational cycles and are proven to provide estimated battery parameter convergence with reasonable accuracy. However, embedding optimization routine after UAS based adaption process can help to increase the accuracy of battery parameters. The UAS based APE strategy assists in narrowing search space for the optimization method following the adaptive estimation and, thus, renders the optimization process highly efficient in terms of computational time required to produce accurate results. The simulation results are validated against a well-known experimentally validated Li-ion battery model.
Bromate is carcinogenic substance introduced into drinking water in the process of ozonolysis. Various forms of activated carbon have been used for its removal, while other classes of materials have been neglected as viable sorbents. Herein, we synthesized a cationic porphyrinbased covalent organic framework (COF) through the Zincke reaction. The COF exhibited the morphology of uniform spheres, which were used as-synthesized, post-synthetically metallated with Zn, or had their cationic viologen subunits fully reduced to neutral. The three COFs were tested for bromate removal at an industrially relevant concentration of 50 ?g/L. The as-synthesized COF performed best, removing over 95 % at a rate of 191.45 g/mg/min, which is one of the fastest rates of adsorption reported till date, and bringing bromate concentration down to well below the permitted drinking water concentration of 10 ppb. The same COF reached a maximum uptake capacity of 203.8 mg/g, one of the highest values reported.
This paper proposes adaptive tuning of PI gains using modified high-gain adaptive controller to overcome fixed PI gains performance degradation in the presence of external disturbances and motor parameters variation. This adaptive gain tuning mechanism depends on the speed tracking error signal. High-gain adaptation of PI gains, although stable in many applications, is unstable for induction motor. This instability is caused by the ever-increasing PI gains and is the result of the persistent error sources such as encoder readings. Therefore, different modifications on high-gain such as sigma, dead zone, and epsilon modifications are proposed to overcome the instability of the high-gain PI tuning. The performance of high-gain adaptive PI controller with these modifications is experimentally investigated on an Indirect Field Oriented (IFO) induction motor drive system. It is shown that dead zone and epsilon modified high-gain adaptive PI controllers outperform the fixed gains PI controller when evaluated based on speed profile and torque commanded current.
In this study, a set of ceria-based catalysts were synthesized using microwave radiation coupled with sol-gel method for CO oxidation in Proton Exchange Membrane Fuel Cells (PEMFCs). The effect of Cu loading, and synthesis medium were investigated. The obtained catalysts exhibited particles with a random-shaped and a macroporous texture (SEM and porosity studies). The XRD characterization confirmed the solid-solution formation with the exception of Ce-Sm-20Cu material. Representative Raman spectra were collected in a complementary fashion with XRD. The Raman results supported the formation of fluorite cubic cell of ceria (F2g band) and the presence of oxygen vacant sites. The CO oxidation tests exhibited that the catalytic activity increases as the Cu loading increases in the Ce-Sm-xCu (x: 3, 5, 7, 10 and 20 at.%). The T50?the temperature at which 50% of the CO is converted?for the various catalysts showed a decrease in the temperature (i.e. higher activity) as the at.% Cu is increased.
Four-dimensional (4D) printing uses time-activated materials in the process of 3D printing which allows manufacturing of complex structures that change shape with time. Smart materials such as Shape Memory Polymers (SMP) exhibit the ability to change shape when subjected to heat, this allows programming of structures that can alter their properties with their shape (property tuning). The emergence of 4D printing in research requires the further investigation of the behavior of 3D printed SMPs to better clarify its behavior when made into usable application. This work aims to address the elastic behavior of a 4D printed dumbbell specimen under multiple constant programming displacement cycles. In addition, the tunability of elastic behavior is addressed by increasing programming displacement. Results indicates the negligible effect of programming cycles on the elastic behavior and the ability to tune elastic properties of 3D printed SMP materials.
This paper presents battery energy management system (BEM) in electric vehicles that run on an indirect field-oriented control (IFOC) drive system. This IFOC utilizes a Model Predictive Controller (MPC) as a speed regulator that takes into account the State of Charge (SOC) of the battery and optimizes the energy consumed from the battery by adjusting the induction motor stator current Iq. The MPC incorporates the SOC information into the optimization algorithm by adjusting the weights on the control signal Iq thus restricting its variation and consequently reduce the SOC usage. Simulation results have been obtained and a comparison between the conventional speed control MPC and an MPC with tuned weights demonstrate that both speed controllers managed to reached the required speed; however, when the SOC was used to determine the weights on Iq in the MPC, the total SOC usage was significantly reduced and therefore the battery life was extended.
Poly lactic acid (PLA), a biodegradable polymer that is derived from renewable raw materials such as corn starch and sugarcane, was used as a thermoplastic matrix in order to develop a biodegradable thermal insulation material. The Date-Pit powder (DPP) was used as a filler in the prepared renewable composites. The samples were prepared with different percentages weights of DPP (0-40 wt. %) using melt extruder and compression molding machine. PLA-DPP composites were then checked to different thermal and mechanical properties. Increasing the DPP content led to a decrease in the thermal conductivity of composite. Adding the date pit to PLA matrices reduced slightly the mechanical strength of composites, however, the measured mechanical strength was greater than that of many commercial heat insulators.
