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Design and development of green energy conversion system using waste water and organic kitchen wastes.
No full textThe design aspects and operational methodologies of a prototype microbial fuel cell and kitchen wastes based GECS are presented in this paper. The objective of this innovative research work is to provide an engineering solution for power generation from kitchen water, organic and agricultural wastes in green and biocompatible manners. The aluminium and copper foil sheets as cathode and an anode respectively are used as an electrode in the developed GECS. The comprehensive experiments have been performed using different bio-fuels from kitchen waste samples in bio-electric sandwich GECS chamber. The design and working aspects of GECS under anaerobic and aerobic conditions are described and discussed in this paper. The sandwich design of developed GECS comprises a bottom chamber and bio-fuel disposal chamber with 24 cassettes array. The output terminals of the 24 cassettes array arrangement produce 6 to 12 volts and exhaust byproduct as the liquid bio-fertilisers
System identification of flybar-less rotorcraft UAV (2020) Aircraft Engineering and Aerospace Technology,
No full textThis paper aims to build an accurate mathematical model which is necessary for control design and attitude estimation of a miniature unmanned rotorcraft and its subsequent conversion to an autonomous vehicle. Design/methodology/approach: Frequency-domain system identification of a small-size flybar-less remote controlled helicopter is carried out based on the input–output data collected from flight tests of the instrumented vehicle. A complete six degrees of freedom quasi-steady dynamic model is derived for hover and cruise flight conditions. Findings: The veracity of the developed model is ascertained by comparing the predicted model responses to the actual responses from flight experiments and from statistical measures. Dynamic stability analysis of the vehicle is carried out using eigenvalues and eigenvectors. The identified model represents the vehicle dynamics very well in the frequency range of interest. Research limitations/implications: The model needs to be augmented with additional terms to represent the high-frequency dynamics of the vehicle. Practical implications: Control algorithms developed using the first principles model can be easily reconfigured using the identified model, because the model structure is not altered during identification. Originality/value: This paper gives a practical solution for model identification and stability analysis of a small-scale flybar-less helicopter. The estimated model can be easily used in developing control algorithms
Wind profile estimation during flight path reconstruction
No full textAccuracy of flow angles measurements becomes crucial as the aircraft approaches higher angle of attack. Flight path reconstruction (FPR) is an excellent tool for air data calibration. An important element of air data calibration is the estimation of wind velocities. The objective of this paper is to evaluate different approaches of wind estimation within the framework of FPR.
Flight test data of a high performance aircraft is subjected to FPR and the estimated wind velocities and flow angle trajectories are presented and discussed to demonstrate the impact of wind estimation on aircraft flow angles. Results clearly show that accuracy of reconstructed flow angles improves when time varying wind models are used. The proposed analytical wind model is found to be as effective as augmented parameters in Extended Kalman filter and computationally less intensive
Sputter deposited p-NiO/n-SnO2 porous thin film heterojunction based NO2 sensor with high selectivity and fast response
No full textIn this work, we report fabrication and characterization of porous, single layer n-SnO2, p-NiO and bilayer thin film heterojunction devices developed using pulsed DC magnetron sputtering for NO2 detection. Template-free, NiO/SnO2 heterojunction devices were deposited both in top-bottom and in-plane electrode configurations. All the devices showed an optimum sensing temperature of 200 °C. Systematic comparison of the fabricated devices revealed that the heterojunction devices with top-bottom electrodes improved performance. Electrical characterization confirmed the formation of heterojunction across the interface. The response values of the heterojunction sensor ranged from 57 to 144 % for the NO2 concentration range of 2–10 ppm. The heterojunction device showed high selectivity against CO and NH3 with selectivity coefficients of 90 and 26, respectively. The heterojunction sensor exhibited fast response and recovery times of 37 and 98 s, respectively. The device showed excellent stability with < 2 % variation in response for 10 cycles of transient response characteristics. The I–V characteristics of heterojunctions with top-bottom and in-plane electrodes were explained by an equivalent circuit model. The observed enhancement in various parameters can be ascribed to the formation of distributed p-n nano-heterojunctions across the interface. The developed NiO/SnO2 heterojunction sensor by the simple and reproducible sputtering technique is found to be a promising candidate for the detection of NO2
Fatigue Crack Growth Behavior of a Nickel-Base Super Alloy Inconel 718 Under Spectrum Loads.
No full textFatigue crack growth behavior of a nickel-base super alloy Inconel 718 under a standard mini-FALSTAFF spectrum load sequence was determined experimentally. Fatigue tests were performed in a 100 KN servo-hydraulic test machine at RT and lab air atmosphere using Compact Tension, C(T) specimens. Triangular waveform at an average frequency of 5 Hz was employed in testing. The crack length was observed to increase with applied spectrum load blocks, slowly in the beginning and rapidly as the crack length increased further to fail after about 58 blocks of loading. Further, the crack growth behavior under spectrum load was predicted and compared with experimental results. For prediction purpose, constant amplitude (CA) fatigue crack growth rate (FCGR) data at different stress ratios was analyzed to derive a crack growth law based on a two-parameter crack driving force ΔK*. The crack extension per load block was estimated using this crack growth law. The predicted fatigue crack growth behavior was observed to be conservative and comparable with experimental results
Structure, ferroelectric and piezoelectric properties of KNN-based perovskite ceramics
No full textInfluence of donor (Ba) and acceptor (Ni) dopants on structure, microstructure, dielectric, ferroelectric and piezoelectric properties of (K0.5Na0.5)NbO3 ceramics have been studied. Dielectric parameters and effective d33 piezoelectric coefficients changes were observed depending on solid solutions compositions
Multiscale material modelling and analysis of carbon fiber/MWCNT/ epoxy composites to predict effective elastic constants
No full textIn the current work, the effect of weight percentage and orientation of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties of unidirectional (UD) carbon fiber (CF)/MWCNT/epoxy composites was studied by using multiscale material modelling and finite element analysis (FEA). Nanoscale representative elementary volume (RVE) consisting of MWCNTs and microscale RVE consisting of carbon fibers were generated using DIGIMAT FE Software. The equivalent elastic properties obtained from MWCNT/epoxy composites were used to estimate effective elastic constants of UD carbon fiber/MWCNT/epoxy composites. The weight percentage of MWCNTs was varied 0%–5%, while MWCNTs were orientated at 0°, 30°, 45°, 60° and 90°. It was found that the E1, E2, G12, υ12 and υ23 increased by 1.79%, 6.14%, 2.83%, 8.8% and 5% at 5 wt% addition of MWCNTs respectively. It was also found that except transverse young's modulus (E2) all other elastic constants decreased by increasing the orientations and at 90° the transverse Young's modulus (E2) increased by 16.57% compared to 0° orientation at 1 wt% addition of MWCNTs. The multiscale FE analysis results were compared by multiscale micromechanics model
Microstructure and mechanical properties evolution of aa 2024 alloy subjected to RCS
No full textThis work has been aimed to evaluate the ability of repetitive corrugation and straightening (RCS) technique in fabricating ultra-fine grained Al-Cu alloy as well as to determine the hardness and microstructural evolution and its influence on grain size refinement.
Aluminium alloy (AA-2024) has been successfully subjected to repetitive corrugation and straightening (RCS) up to 8 passes at room temperature. The influence of rotation of sample between each pass has been studied. The improved mechanical properties have been observed for the samples which have been rotated during each RCS pass. The grain refinement results clearly demonstrate that an average grain size of α-Al has been reduced 0.7 microns after 8 pass RCS from 30 microns of as cast condition sample. Similarly, the tensile strength has also been increased (8
pass RCS processed) to 265 MPa from 140 MPa (as cast condition). The improved mechanical properties are basically due to the grain refinement effect due to RCS and presence of fine Al2Cu precipitates. Thus, it is demonstrated that RCS as a promising new method for producing ultra-fine grained Al alloys. As a result, development of new Al alloys with unique mechanical properties has in great demand in aerospace sector. This paper contributes to the mechanical properties of Al-Cu alloy with Al2Cu precipitates strengthened ultra-fine grain size subjected to RCS method
Analytical method of radiation mode radar cross section (RCS) of low profile phased arrays
No full textThe Radar Cross Section (RCS) of a phased array comprises of two scattering modes, the antenna (or the radiation mode), and the structural mode [1]. The antenna mode RCS depends on the radiation behavior of the antenna array. The structural mode arises from the currents induced on the antenna and the platform. In case of phased array, the structural RCS also signifies the case when the antenna array is matched with the feed network. However, it is not practically possible to achieve such perfectly matched antenna array. The feed structure of the phased array itself contributes to most of the impedance mismatches and hence scattering. When the incident energy strikes the phased array, it traverses through the components of feed network, viz. phase shifters, couplers, and load impedances. Each feedline of a certain feed width acts as a transmission line having finite input and characteristic impedance. At every junction of impedance mismatch, a portion of incident wave is reflected and rest is transmitted further in to the feed network. The coherent sum of all these reflections within the array and its feed structure contributes to the total radiation mode RCS [2], which is significantly higher than the structural mode RCS. This makes the study of radiation mode RCS most important especially for a radiating phased array. This paper proposes a novel analytical method to estimate the radiation mode RCS of a low profile patch array. The incident wave is traced as it travels from the array aperture into the feed network. The scattered field contribution from each component of feed network is expressed in terms of the reflection and transmission coefficients. The individual contributions are then coherently superimposed to arrive at total array RCS, given by
Ferroelectric and local piezoelectric properties of modified KNN ceramics
No full textInfluence of cation substitution on structure parameters, microstructure, dielectric, ferroelectric and local piezoelectric properties of (K0.5Na0.5)NbO3 ceramics additionally modified by Li+ and Mn3+ cations (up to 10 at. %) have been studied. Changes in dielectric properties and effective d33 piezoelectric coefficients were observed depending on compositions of solid solutions