Effect of manuring and frequency of cutting on the yield of leaf protein from some fodder grasses

A study to find out the effect of manuring and the frequency of cutting on the yield of leaf protein was conducted with four fodder grasses. The study revealed that Cenchrus glaucus was superior to the other grasses tried and it gave the maximum yield of dry matter and extractable protein. Farm yard manure at 10 tons/ha along with ammonium sulphate at 33 kg N/ha proved to be the best in giving the highest yield of dry matter and leaf protein. For all the grasses the maximum yield was found to range within the first three cuttings.     

Performance evaluation of an IEEE 802.15.4 sensor network with a star topology

One class of applications envisaged for the IEEE 802.15.4 LR-WPAN (low data rate—wireless personal area network) standard is wireless sensor networks for monitoring and control applications. In this paper we provide an analytical performance model for a network in which the sensors are at the tips of a star topology, and the sensors need to transmit their measurements to the hub node so that certain objectives for packet delay and packet discard are met. We first carry out a saturation throughput analysis of the system; i.e., it is assumed that each sensor has an infinite backlog of packets and the throughput of the system is sought. After a careful analysis of the CSMA/CA MAC that is employed in the standard, and after making a certain decoupling approximation, we identify an embedded Markov renewal process, whose analysis yields a fixed point equation, from whose solution the saturation throughput can be calculated. We validate our model against ns2 simulations (using an IEEE 802.15.4 module developed by Zheng [14]). We find that with the default back-off parameters the saturation throughput decreases sharply with increasing number of nodes. We use our analytical model to study the problem and we propose alternative back-off parameters that prevent the drop in throughput. We then show how the saturation analysis can be used to obtain an analytical model for the finite arrival rate case. This finite load model captures very well the qualitative behavior of the system, and also provides a good approximation to the packet discard probability, and the throughput. For the default parameters, the finite load throughput is found to first increase and then decrease with increasing load. We find that for typical performance objectives (mean delay and packet discard) the packet discard probability would constrain the system capacity. Finally, we show how to derive a node lifetime analysis using various rates and probabilities obtained from our performance analysis model.

Impact of crystal structure and microstructure on electrical properties of Ho doped lead-free BCST piezoceramics

Conventional solid state sintering method was used to synthesize lead-free (Ba_0.91Ca_0.09Sn_0.07Ti_0.93)O₃-xHo₂O₃ (x?=?0, 1.2,1.4,1.6,1.8 and 2.0?mol%) ceramics. The influence on electrical properties of the system as a result of the structural and microstructural changes introduced by the incorporation of rare earth Ho³⁺ ions has been investigated. The X-ray diffraction analysis reveals that Ho³⁺ ions completely diffuse into the (Ba_0.91Ca_0.09Sn_0.07Ti_0.93)O₃ lattice to form a homogeneous solid solution with a pure perovskite structure having tetragonal symmetry. Evidence of Ho³⁺ substituting Ti⁴⁺ via the oxygen vacancy compensation mechanism exists in the range of 0–1.6?mol % Ho content, while the self-compensation mode is the preferred mechanism beyond 1.6?mol %. The average grain size exhibits a drastic reduction from 16?μm to 0.7?μm as the Ho content increases from 0 to 1.6?mol%, followed by a slight increase at higher Ho concentration. It suggests that addition of Ho³⁺ inhibits grain growth in the ceramics. In the composition range studied, increasing Ho³⁺ content produces a gradual decrease in the relative density from 93% to 81%, room temperature dielectric constant (ε_rt) from 3997 to 807, electromechanical coupling factor (k_p) from 0.23 to 0.06, and piezoelectric charge constant (d₃₃) from 102 to 38?pC/N. This degradation in the properties is attributed to the crystalline and microstructural changes driven by the increasing presence of Ho content in the ceramics.     

Physico-mechanical and Surface Wear Assessment of Magnesium Oxide Filled Ceramic Composites for Hip Implant Application

Silicon - In the present study, applicability of ceramic composites as ceramic-on-ceramic hip prostheses is explored. Hence, ceramic composites containing zirconium oxide, silicon nitride, chromium...     

Improved gait recognition through gait energy image partitioning

Recently, human gait pattern has turned into an essential biometric feature to recognize an individual remotely. Gait as a feature becomes challenging owing to variation in appearance under different covariate conditions (eg, shoe, surface, haul, viewpoint and attire). The covariates may alter few fragment of gait while other fragment stay unaltered, leading to lower the probability of correct identification. To overcome such variation, an improved gait recognition strategy is proposed in this article by gait energy image partitioning and selection processing. Our method involves pre-processing of raw video for silhouette extraction, gait cycle detection, segmentation into different regions, and histogram of gradients feature extraction from selected segments. In this way, the specific features across complete gait cycles are extracted precisely. Finally, recognition is done by using K-NN. The proposed strategy has been assessed using the CASIA B gait database. Our outcomes shows a particular proposed strategy accomplishes high recognition rate and outperforms the advanced gait recognition mechanism.     

Ion transport in Au<Superscript>+</Superscript> doped/undoped KDP crystals with KI/NaI as additives

Undoped KDP and KDP crystals containing KI/NaI with/without gold doping were grown by slow evaporation technique. All the grown crystals were γ-irradiated using⁶⁰Co source. Electrical conductivity measurements were carried out on all these crystals perpendicular to the unique direction before and after y-irradiation. The present results show that the conductivity of KDP crystals increases with the addition of KI/NaI and with gold doping as well as upon rise in temperature. Computed values of activation energies from the conductivity measurements are given. For all the grown crystals, dielectric constant is measured as a function of frequency.     

Size effect on piezoelectric properties of barium stannate titanate ceramics prepared from nanoparticles

Piezoelectric properties of Ba(Ti_1?x Sn _x )O₃ ceramics with x = 0.025, 0.045 and 0.065, prepared from 16 nm powders, were compared with those of the corresponding ceramics obtained from 86 nm powders to see the effect of tin content and particle size of the starting powders. Ba(Ti_1?x Sn _x )O₃ powders were synthesized by solid state reaction of BaCO₃, TiO₂ and SnO₂ at 1,050 °C. The powders were high energy ball milled to produce nanocrystalline powders having average particle size of 16 nm. The milled powders were sintered at 1,350 °C for 4 h to yield ceramics. For these ceramics, increasing Sn content from x = 0.025–0.065 produces a decrease in (1) unipolar strain level s from 0.084 to 0.027 %, and (2) electromechanical coupling factor k _p from 33.6 to 19.3 %. However, the bulk density, room temperature dielectric constant and piezoelectric charge constant d ₃₃ exhibit an increase from 5.03–5.84 g/cm³, 1,342–2,156 and 7–110 pC/N, respectively, with increasing Sn content. The increasing trend of density and d ₃₃ presently observed is in sharp contrast to the result of corresponding ceramics prepared from 86 nm nanopowders. The present study reveals a cooperative mechanism involving both the nanoscale size of the starting particles and optimum tin content which results in the enhancement of d ₃₃ with tin content.     

Fabrication of Ceramic Hip Implant Composites: Influence of Silicon Nitride on Physical,Mechanical and Wear Properties

This study examined the effects of silicon nitride reinforcement on physical, mechanical and wear properties of different ceramic (zirconium oxide, magnesium oxide, chromium oxide and aluminum oxide) containing hip implant composites. The hip implant composites were produced using conventional mixing and spark plasma sintering methods by substituting aluminum oxide (68, 70.5, 73 and 75.5 wt.%) with silicon nitride (0, 2.5, 5 and 7.5 wt.%). Experimental results showed that silicon nitride content had significant effect on the evaluated physical, mechanical and wear properties. The density of the composites found to decrease whereas void content, Young’s modulus, hardness, wear resistance and fracture toughness first decreased (for 2.5 wt.%) and then increased with the increasing amount of silicon nitride content. The maximum hardness, Young’s modulus, wear resistance and fracture toughness values of 28.64 GPa, 280.18 GPa, 0.0076 mm³/million cycles and 11.84 MPa.m^1/2, respectively were registered for 2.5 wt.% silicon nitride additions that also had the lowest void content (0.38%).

     

Structural and piezoelectric properties of barium-modified lead-free (K0.455Li0.045Na0.5)(Nb0.9Ta0.1)O3 ceramics

Ferroelectric (K_0.455Li_0.045Na_0.5)(Nb_0.9Ta_0.1)O₃ + x mol% BaCO₃ ceramic compositions with Ba²⁺ as an A-site dopant in the range of x = 0–1.2 mol% were synthesized by conventional ceramic processing route. Effect of Ba²⁺ content on the microstructure, ferroelectric, dielectric, and piezoelectric properties of the ceramics was investigated. The results of X-ray diffraction reveal that Ba²⁺ diffuse into the (K_0.455Li_0.045Na_0.5)(Nb_0.9Ta_0.1)O₃ lattices to form a solid solution with a perovskite structure having typical orthorhombic symmetry. As Ba²⁺ content increases, cell volume and tetragonality increase in the crystal structure of the ceramics. Increasing doping level of Ba²⁺ inhibits grain growth in the ceramics and reduces both the Curie temperature (T _c) and tetragonal–orthorhombic phase transition temperature (T _o-t). The bulk density, remnant polarization P _r, room-temperature dielectric constant (ε′_RT), planar electromechanical coupling factor k _p , and piezoelectric charge coefficient d ₃₃ are found to increase as Ba²⁺ concentration increases from 0 to 0.8 mol% and then decrease as Ba²⁺ content increases further from 0.8 to 1.2 mol%. High piezoelectric properties of d ₃₃ = 187 pC/N and k _p  = 48 % are found in 0.8 mol% Ba²⁺ composition. Optimum amount of Ba²⁺ dopant takes the polymorphic phase boundary region consisting of orthorhombic and tetragonal crystal structures of the ceramic system near the room temperature and enhances its piezoelectric properties.     

Lead-free piezoelectric ceramics manufactured from tantalum-substituted potassium sodium niobate nanopowders

Nanopowders of lead-free (K_0.5Na_0.5)(Nb_0.9Ta_0.1)O₃ (KNNT) system were prepared by high-energy ball milling at different milling times keeping the milling speed fixed at 250 rpm. The particle size first decreases from 35 nm to 3 nm and then increases to 98 nm as the milling time increases in steps of 5 h from 10 h to 30 h. Without using any sintering aid, dense ceramics were formed by sintering the powders at 1050 °C for 1 h. With decreasing particle size of the starting nanopowders, the ceramics exhibit gradual increase in density from 93.1% to 95.8%, coercive field (E_c) from 10.9 kV/cm to 15.1 kV/cm, electromechanical coupling factor (k_p) from 35% to 48%, and piezoelectric charge constant (d₃₃) from 80 pC/N to 128 pC/N. The systematic changes observed in these parameters corroborate the observed increase in particle size as the milling time increases from 25 h to 30 h.