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Rehabilitation evaluation of the newly developed polymeric based passive polycentric knee joint
No full textObjective: The lower limb amputation is one of the major concerns for the amputee’s daily life and the trans-femoral (TF) amputation is being paid a lot of attention because of its functional requirement in flexion-extension motion. Though significant progress has been made for the development of high end prosthetic knee joint, the affordability of the same is still a great concern. Thus, a passive polycentric knee joint was developed and the health related quality of life (HRQL) before and after the fixation of the prosthesis, and performance of the same were studied. Design: After 6 months of fixation, the HRQL and performance of the prosthetic device were evaluated. Results: The HRQL after the fixation was found to be increased, where the improvement on the physical and mental score was found to be 49 and 46%, respectively, in comparison with pre-fixation stage. The global score (G) for the prosthetic function was found to be 63, which confirmed the increased performance of the prosthesis. Conclusions: The improved HRQL and G of prosthetic performance confirmed the enhanced performance of the prosthesis. It is concluded that the developed passive polycentric knee joint could be explored in large scale for the TF amputees.Implications for rehabilitation The above knee (AK) amputation is a surgical interference that severs the thigh segment between the knee and hip joints. The above knee prosthesis consists of a socket, knee joint, pylon and foot. The artificial prosthetic knee joint imitates the functions of human knee to achieve the flexion-extension motion of the above knee amputee. The satisfaction of the amputees with the usage of the existing artificial prosthetic knee joint is still a concern. Hence, a passive prosthetic knee joint was developed and its effect on the quality of life of trans-femoral amputee was evaluated using health related quality of life (HRQL) before and after the fixation of the prosthesis The HRQL after the fixation was found to be increased in comparison with pre-fixation stage. The global score for the prosthetic function was also found to be increased which confirmed the increased performance of the prosthesis. It is anticipated that the developed knee joint is expected to make huge impact due to its function, performance and affordability
Synthesis, comparison and analysis of graphene
No full textCarbon, Graphite and Diamond are the three forms. Carbon and Graphite are having good conducting properties. Graphene is also a form of graphite and many synthesis methods like mechanical exfoliation, chemical exfoliation, chemical synthesis; Chemical vapor deposition and many more are existing. Experiments to synthesize graphene through electrochemical exfoliation method are used. It gives the comparison of results of the samples when supplied with 5 V and 10 V separately. Also Emissions of the castor oil are also tested. It is found that 10 V sample exhibits good results compared to others
Thermodynamically consistent approach for one-dimensional phenomenological modeling of shape memory alloys
No full textThe present work investigates the thermodynamic inconsistency in the definition of constant and nonconstant material functions for the one-dimensional shape-memory alloy constitutive models, with respect to the first principles. Thermodynamic consistency for the onedimensional shape memory alloy differential equation is also investigated within the framework of one-dimensional elasticity at different length scales of stress and martensite fraction. It is shown that the previously proposed improvements in constitutive models using compatible nonconstant material functions cannot be derived from the first principles, yielding inconsistencies in the definition of the differential form of the constitutive relations. Additionally, the compatibility conditions on stress due to the previously defined compatible material functions in terms of constant and nonconstant material functions are also discussed. Derivations are provided to highlight the inconsistencies in the definition of differential form of constitutive relation due to previously proposed expressions for material functions. Finally, in this work new expressions for the differential equation with constant material function and corresponding transformation tensor are derived from the first principles. Subsequently, a consistent form of a differential constitutive model for shape-memory alloys is proposed. The discussions highlight that there is further requirement to propose compatible forms of nonconstant material functions through consistent definition of differential form of constitutive relation, which may help to further rebuild the 2D and 3D SMA models based on multiscale modeling
High-temperature stable spinel nanocomposite solar selective absorber coating for concentrated solar thermal application.
No full textA new Cu-Ni-Co ternary spinel/SiO2 nanocomposite oxide absorber with tandem layer approach is designed and
developed for medium and high temperature solar selective receiver tube in concentrated solar thermal applications.
The base absorber layer, developed by combining of nanostructured, transition metal spinel and composite oxides with a series of transition metal based salts (Co, Ni, and Cu) in wet chemical method. By optimizing the sol
concentration, withdrawal speed and annealing temperature, uniform absorber layer with solar absorptance (α) of 0.91 and emittance (ε) of 0.14 were achieved in a single layer coating with a composite oxide formation. On top of the base absorber layer, coating integrated with silica (SiO2) nanoparticles added as an optical enhancement layer to make the coating more selective (α: 0.95 & ε: 0.13). A thorough characterization has been done for the optical and
physiochemical properties of the samples. Besides, the optimized spinel coating exhibits a low radiative loss of about 0.18 thermal emissivity at 500 °C and 89.3 % photothermal conversion efficiency at 500 °C, which identifies that the spinels are a very good candidate for medium and high temperature solar selective absorbers
A two-step approach for synthesis, characterization and analysis of dicyclopentadiene–urea formaldehyde–siloxane-based double-walled microcapsules used in self-healing composites
No full textMicroencapsulation is a widely used method for making healing agents used in self-healing composites. In this study, a novel two-stage process was used to make double-walled microcapsules. Dicyclopentadiene–urea formaldehyde (DCPD–UF) microcapsules were synthesized by in situ polymerization of oil-in-water emulsion followed by siloxane coating through ‘sol–gel process’ (DCPD–UF–siloxane microcapsules). Average diameter of microcapsules, UF shell thickness and siloxane coating thickness were found to be 300, 1.4 and 16 µm, respectively. The effect of addition of microcapsules on rheological properties of epoxy was studied. Breaking pattern of single-walled and double-walled microcapsules immersed in epoxy was analyzed by continuous monitoring of the deformation behavior through a rheometer–microscope arrangement, confirming improved mechanical properties of the double-walled microcapsules. In this study, epoxy resin cast specimens with and without microcapsules were prepared and the effect of microcapsules on mechanical properties was examined. Epoxy specimens with double-walled microcapsules were found to be having improved mechanical properties compared to those with single-walled microcapsules. Finally, healing efficiency of DCPD–UF–siloxane microcapsules in epoxy was observed to be marginally higher, and therefore, this double-walled microcapsule system is shown to be a promising candidate for further self-healing composite investigations
Evaluation of Delfino (TMS320F28379D) Processor for Helmet ANC Application
No full textEmbedding Active Noise Control (ANC) system to fighter aircraft helmet imposes size constraint for the controller board as it needs to be integrated inside ear cup. Further ANC system development needs to take place under stringent weight and power constraints. Selection of a suitable processing platform plays a key role in meeting the requirements. This paper proposes to use TMS320F28379D, a microcontroller with DSP capabilities. Evaluation is done by carrying out single channel ANC simulation. Also, the size, weight and power consumption of the ANC controller achievable with this processor is worked out to ascertain that it can be integrated into the helmet
Modelling and Simulation of VOR ILS Receiver Diagnostic Model for Avionics Systems Health Management
No full textEarlier avionics generation utilized federated architecture with individual resources for each application in Line Replaceable Units (LRU). The rapid development of mechanisms, techniques and technology enabled use of the integrated architecture. Avionics system covers the autopilot, communication, indicating and recording systems, warning systems, radar systems, navigation and surveillance systems. Over a period of time, the technology has uplifted the availability and maintainability of avionics systems with rigorous Built In Test (BIT) capability to provide the health information of self to other subsystems. However, BIT capability does not provide sufficient information for complete diagnostic and prognostic management of avionics system. Hence, it is essential to design, develop and implement the avionics system health management methodology in addition to the BIT capability. This paper presents simulation and modelling covering study, understanding, simulation of faults and system behaviour functioning under these simulated faults to establish the complete system behaviour as part of health management
Double doping effect on ferroelectric and leakage current behavior of Pb(Zr0.52Ti0.48)O3 thin film
No full textTo study the double doping effect on PZT, following thin films were prepared with stoichiometric compositions of Pb(Zr0·52Ti0·48)O3(PZT), Pb0·92La0·08(Zr0·52Ti0·48)0.98O3(PLZT) and Pb0·92(La0.5Yb0.5)0·08(Zr0·52Ti0·48)0.98O3(PLYZT) by chemical solution deposition method. XRD results revealed tetragonal crystal structure of all the three thin film compositions with significant changes in lattice parameters for La3+and La3+-Yb3+ doped PZT film. Raman study confirmed XRD results. The influence of structural changes on ferroelectric behavior was investigated by studying ferroelectric switching current, remanent polarization and coercive field. An increase in ferroelectric switching current and decrease in coercive field was observed in double doped (La3+ and Yb3+) PZT thin films than the pure one. This result indicates easy domain switching in doped PZT thin films. The double doping has reduced leakage current in PZT by compensating oxygen vacancy and thereby improved the polarization fatigue
Control of incident shock-induced boundary-layer separation using steady micro-jet actuators at M∞ = 3.5
No full textExperiments were carried out to control an incident shock-induced separation associated with 22° shock generator in a Mach 3.5 flow using an array of steady micro-jet actuators. Four micro-jet actuator configurations based on the variation in their pitch angle (β), skew angle (α) and span-wise spacing were used. Each of these configurations were placed 14δ upstream of the interaction and operated with injection pressures (Poj) varying from 140 to 643 kPa. While no major variations in separation characteristics were observed for Poj < 140 kPa, significant modifications were observed beyond Poj of 140 kPa and until 208.5 kPa. Amongst all the four control configurations, micro-jet vortex generator 2 (β = 180° α = 45° showed the best control with a 2δ downstream shift in separation point location relative to no-control. The shift is also accompanied with a change in maximum zero-crossing frequency towards higher frequency (almost twice), a reduction in the intermittency length and an increase in the correlation value between the boundary layer just upstream of the interaction and the intermittent region. These results indicate that the effectiveness of micro-jet vortex generator 2 is probably due to the improved entrainment levels in the shear layer induced by the micro-vortices which are generated downstream of these devices. The increase of the skew angle (α) from 180° to 270° for the same pitch angle of
β = 45° (micro-jet vortex generator 3) seems to have no major impact on the separation characteristics. The reduction in the span-wise spacing (micro-jet vortex generator 4) resulted in deterioration of the flow field due to the jet-to-jet interaction with increasing injection pressures
Electromagnetic shielding, magnetic and microwave absorbing properties of Polypyrrole/ Ba0.6Sr0.4Fe12O19 composite synthesized via in-situ polymerization technique
No full textIn this article, we have synthesized the Polypyrrole/Ba0.6Sr0.4Fe12O19 (PBSF) composite via in-situ polymerization technique. The synthesized samples were further characterized for structural, electrical, magnetic and microwave absorbing characterizations. The X-ray diffraction patterns reveal the formation of pure hexagonal ferrite phase whereas the Fourier transform infrared spectrums and X-ray photoelectron spectroscopy confirms the formation of polypyrrole/BSF composite structure. The microwave absorbing and shielding properties were studied in the frequency range 8–18 GHz. Using X and Ku band. The magnetic properties were studied using VSM and the PBSF37 composite shows the highest magnetic moment 59.58 emu/gm rather than the other PBSF composites and pure BSF ferrite. The PBSF37 shows the maximum microwave absorption of 89% over the broadband frequency range 8–18 GHz. The maximum shielding effectiveness 37.49 dB at 15.2 GHz corresponding maximum microwave properties were also observed for the same sample