Evolvable Hardware Based Optimal Position Control of Quadcopter

Trading off performance metrics in control design for position tracking is unavoidable. This has severe consequences in mission-critical systems such as quadcopter applications. The controller area and propulsion energy are conflicting design parameters, whereas the reliability and tracking speed are related metrics to be optimized. In this research, a switching-based position controller was co-simulated with the quadcopter model. Performance analysis of the Field Programmable Gate Array (FPGA)-based controller validates a better scheme for tracking speed, propulsion energy, and reliability optimization under similar error performance. To improve the computation power and controller area, the dynamic partial reconfiguration(DPR) approach has been adapted and implemented on FPGA using the Vivado Integrated Development Environment (IDE), where a ranking-based approach brings into action either proportional derivative, sliding mode, or model predictive controllers for each dimension of position tracking. It is verified by analyzing the cumulative tracking speed, reliability, controller area, and propulsion energy metrics that the proposed controller can optimize all these metrics within three successive iterations of tracking either in the same direction or in any combination of directions. Concerning the implementation results of the controller with the switching-based controller, there is 6 % computation power and 30 % resource savings due to DPR

Effect of V-shaped Ribs on Internal Cooling of Gas Turbine Blades

Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperature. The rotor inlet temperatures in most gas turbines are far higher than the melting point of the blade material. Hence the turbine blades need to be cooled. In this work, simulations were carried out with the leading edge of gas turbine blade being internally cooled by coolant passages with V-shaped ribs at angles of 30°, 45° or 60° and at three aspect ratios (1:1, 1:2 and 2:3). The trailing edge of the blade was cooled by cylindrical and triangular pin-fin perforations in staggered and inline arrangements. Numerical analyses were carried out for each configuration of the cooling passages. The best cooling passages for leading edge and trailing edge were deduced by comparing the results of these analyses. It was found that using V-shaped ribs and fins induces a swirling flow, which in turn increases the velocity gradient and hence produces an improvement in heat transfer. The results show that under real time flow conditions, the application of V-shaped ribs and pin-fin perforations is a very promising technique for improving blade life

Review on Unconventional Wind Energy

Fossil fuel is the major source of energy and is a fast depleting resource. The phenomenal increase in fossil fuel consumption has adversely affected carbon footprint impacting our environment. With strict environmental regulations in place, the focus towards renewable sources of energy is gaining momentum supported by recent advancement in technologies in wind, hydro and solar. Wind turbines were the first forms of clean energy has seen a major increase in power production. The site restrictions, have limited the wind turbine from being used to its maximum potential. In recent years, the concept of some unconventional methods is being proposed. In this review, the various types of wind turbines are emphasized with their recent advances and depicting the challenges faced in various aspects. The reviews contain details mainly about 4 types of wind turbines i.e. floating offshore wind turbine, airborne wind turbine, highway wind turbine systems and locomotive mounted wind turbine

Influence of fabric orientation and compression factor on the mechanical properties of 3D E-glass reinforced epoxy composites

3-D E-glass fabric reinforced epoxy composites at 6 mm thickness were fabricated for various orientations of the binder yarn viz. 0°, 30°, 45°, 60° and 90° respectively. Tensile, flexural, interlaminar shear stress tests were conducted to ascertain the influence of binder yarn orientation on the mechanical properties of the composites. The composites with 0° binder yarn orientation showed the best strength followed by 90° whilst the others showed highly depleted traits in comparison. Shear stress induced at the interface of each lamina was seen as the major reason for drop in the strength. A secondary study was carried out to explore the effect of compression factor during fabrication on the mechanical properties of the composites. Laminates with varying thickness namely, 4 mm, 5 mm and 7 mm but, with same number of plies of 3D E-glass fabric at 0° orientation were fabricated. The test results were compared with the results of 6 mm composites from the primary study. The results showed that, compression factor affected the mechanical properties of the composites and had a direct relation with increasing compression factor up to a certain value beyond which a drop in properties was seen. Composites pressed to a thickness of 5 mm showed the best properties. Drop in properties was attributed to close packing of reinforcement and crushing of fibres leading to inefficient stress transfer. Scanning electron microscopy was employed to understand the modes of failure. The major failure modes observed were delamination, matrix cracking and debonding. Based on the results obtained, these composites can be seen as a material system for applications like ballistic armours, structural renovations and automobile components

A rapid supercritical water approach for one-pot synthesis of a branched BiVO4/RGO composite as a Li-ion battery anode

The application of novel one-dimensional (1D) architectures in the field of energy storage has fascinated researchers for a long time. The fast-paced technological advancements require reliable rapid synthesis techniques for the development of various Multi-metal oxide (MMO) nanostructures. For the first time, we report the synthesis of a single-phase hierarchical one-dimensional (1D) branched BiVO4-Reduced Graphene Oxide (BVONB/RGO) nanocomposite with different weight percent variations of RGO starting from 6, 12, 24, and 26 wt% using the supercritical water method (SCW). The affirmation of the sample characteristics is done through various nano-characterization tools that help in establishing the monoclinic crystal structure, and nano branch morphology along with its physical, and thermal characteristics. Further, the electrochemical behavior evaluations of the fabricated coin cells provide insights into the well-known superior initial cycle capacity of around 810 mA h g−1, showing the superior ability of BVONB structures in storing lithium-ions (Li-ions). Meanwhile, an improved cyclic performance of the pure BVONB/RGO with 260 mA h g−1 is evident after 50 cycles. Finally, the reported rapid single-pot SCW approach has delivered promising results in establishing a material process technique for multimetal oxides and their RGO nanocomposites successfully

Axial-flow compressor analysis under distorted phenomena at transonic flow conditions

Today, the turbomachinery engineering plays a vital role in the field of air breathing propulsion, most importantly the components like compressor, turbine and its possible numerical strategies to improve the overall efficiency especially in the transonic flow conditions. The main objective of this paper is to address the numerical solution for most uncertain problem like unsteady and non-uniform flow across the axial-flow compressor. The axial-flow compressor distorted flow problem is modeled and analyzed by means of a systematic three-dimensional numerical approach. Particularly, the rotor inflow instability implications of an axial compressor stage are carried out. Geometry is created using ROTOR-37 coordinates for numerical analysis and the results are validated in contradiction of experimental data available from literature, by imposing various combinations of Mach numbers from 0.8 to 1.2 and the engine mass flow rate of incoming air. The results highlighted that the rotor blade main distortion effect was noticed at near the tip region and as well as the hub corners of the blade. Numerical simulations also revealed that due to the distortion influence, the stream flow separation on pressure side of the blade is more. Moreover, these calculated figures have more significance for better aero-mechanical features of axial-flow compressor

The scope of acoustic impedance matching of hybrid fiber metal laminates for shielding applications

In a multi-layered shielding material, the sequence of the arrangement of the layers affects the extent of insulation to acoustic waves. In the current work, hybrid composite laminates have been taken up comprising 10 sequences, employing metallic faceplate (AA6061), paperboard, ballistic-grade aramid, and ultra-high molecular weight polyethylene (UHMWPE) fabrics with an epoxy binder. In the theoretical studies, an analytical model for the transmission loss function has been developed by incorporating the multiple wave reflection principle in combination with interface-wise acoustic impedance grading. The analytical model has been validated using the transmission loss functions from numerical and experimental studies on the different sequences. The numerical simulation has been carried out using the harmonic acoustic analysis module, on Ansys R19.0. The experimentation has been carried out on an impedance tube. The results from the analytical model are in good agreement with the experimental and numerical simulation results, the analytical model can be used for predicting the transmission losses of composite laminates

Wear behaviour studies on Grewia Serrulata bast fibre reinforced polymer composites

Development of new materials in place of existing traditional metals and alloys to meet specific requirements is taking place worldwide. Natural fibre reinforced composites are being considered as one of the alternative materials which can find scope in indoor and low load bearing applications. The biodegradability and low density make them attractive, while inherent hydrophilic nature of the fibre is a challenge for the engineering applications. Surface modification to the fibres by chemical treatments makes them as an alternative reinforcement material in the field of composites. In the present work, Grewia Serrulata bast fibres were subjected to chemical treatments and stitched into unidirectional woven fabrics. Treated and untreated fibre reinforced laminates were fabricated by hand layup process. Sliding wear behaviour of the prepared specimens was studied as per ASTM G-99. Materials with relatively lower wear rate are preferred for the tribological applications. The study shows that acetylated Grewia Serrulata fibre reinforced and permanganate treated fibre reinforced polyester samples showed significant wear resistance compared to neat resin and untreated fibre reinforced specimens

Mechanical Characterization and Water Ageing Behavior Studies of Grewia Serrulata Bast Fiber Reinforced Thermoset Composites

Natural fiber-reinforced polyester composites were prepared using bast fibers as the reinforcement which were extracted from Grewia serrulata trees. Chemical treatments such as alkali pretreatment followed by permanganate treatment, acetylation and silane treatment were exclusively applied to modify the fiber surface. Hand lay-up technique with compression molding was adapted for the fabrication of axially oriented fiber reinforced composites. Tensile, flexural and impact strength properties of the specimens prepared were evaluated following the standard procedures. The SEM images of the fractured surfaces shows improvement in compatibility between the chemically treated fibers and the matrix. It was found that the tensile and flexural strengths of chemically treated fiber-reinforced polyester composites have significantly improved when compared to untreated fiber-reinforced polyester specimens. The properties of 1200 hrs water aged specimens were found deteriorated considerably due to diffusion of water into the composite material system. The chemical treatment of fibers prior to fabrication of composites improves the resistance to water absorption tendencies

Wear estimation at the contact surfaces of oval shaped hip implants using finite element analysis

AbstractThe hip joint is one of the most essential joints for transmitting weights to the lower abdomen during day-to-day activities. Loosening of hip implants is mostly caused by wear. The wear assessment during the design stage offers a clear sense of the implant’s life expectancy, and modest adjustments in the design may also greatly enhance the implant’s life expectancy, lowering the probability of revision surgery. Linear wear is estimated at the contact surfaces of the femoral head to the acetabular cup and the acetabular cup to the backing cup in this study. In this work, oval-shaped hip implant is considered with a femoral head diameter of 28 mm, an acetabular cup thickness of 4 mm, and a backing cup thickness of 2 mm. The Archard’s law used to estimate the linear wear rate. It is observed that when the acetabular cup is made of UHWMPE and the stem, femoral head, and backing cup are made of CoCr, the least overall deformation is 0.394 mm during walking loads. When the stem is considered Ti−6Al−4 V and the acetabular cup of UHWMPE, the minimum wear between the femoral head and acetabular cup is 0.063 mm/year. During a typical standing posture, an acetabular cup-to-backing cup wear rate of 0.007 mm/year is estimated. Overall, the CoCr material combination had the lowest wear rate in the four activities considered for this work. These implants designs can be 3D-printed and further can be tested in a hip simulator under the same loading conditions