2,398 research outputs found

    Complexes of Some Group(IV) Metal Halides with 5-Aminoindazole

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    The synthesis and characterisation of Sn(IV) halides, Ge(IV), Ti(IV) and Zr(IV) chloride complexes of the type MX4 : Li_ 2 with 5-aminoindazole has been made. The possible structure of these complexes has been proposed on the basis of elemental analysis and infrared spectroscopy. The IR spectra suggest unidentate behaviour of the ligand involving pyrrole nitrogen in all the cases except the tin(IV) bromide complex, where the ligand exhibits its bidentate nature, involving the pyridyl nitrogen. An octahedral geometry has been proposed for all the complexes. In the case of MX4 :\u27L type complexes, except for SnBr4 : L, an octahedral halogen bridged structure has been proposed

    Complexes of Some Group(IV) Metal Halides with 5-Aminoindazole

    Get PDF
    The synthesis and characterisation of Sn(IV) halides, Ge(IV), Ti(IV) and Zr(IV) chloride complexes of the type MX4 : Li_ 2 with 5-aminoindazole has been made. The possible structure of these complexes has been proposed on the basis of elemental analysis and infrared spectroscopy. The IR spectra suggest unidentate behaviour of the ligand involving pyrrole nitrogen in all the cases except the tin(IV) bromide complex, where the ligand exhibits its bidentate nature, involving the pyridyl nitrogen. An octahedral geometry has been proposed for all the complexes. In the case of MX4 :\u27L type complexes, except for SnBr4 : L, an octahedral halogen bridged structure has been proposed

    The sintering temperature effect on the shrinkage behavior of cobalt chromium alloy

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    Problem Statement: Co-Cr based alloys which is well known for its high Young’s modulus, fatigue strength, wear resistance and corrosion resistance is an important metallic bio�material. However, till date there are only two type of Co-Cr alloy which are the castable and wrought cobalt alloy. Powder Metallurgy route for cobalt is expected to give better result of Co-Cr alloy. The purpose of this research was mainly to study the sintering temperature effect to the shrinkage behavior of Cobalt Chromium (Co-Cr) alloy of the powder metallurgy route. Approach: Co-Cr was produced following P/M route under sintering temperature of 1000, 1100, 1200, 1300 and 1400oC. The sintering time was fixed at 60 min. Several tests has been conducted to determine this effect such as the rate of shrinkage measurement, the bulk density and porosity percentage measurement, compression and hardness tests and micro structural study. Result: From the study, it was found that the sintering temperature has caused the shrinkage of Co-Cr. The increasing of the sintering temperature has caused to the increasing of shrinkage of Co-Cr. This has resulted to the reduction of the pore volume and hence increased it density. In conjunction to that, the strength and the hardness of Co-Cr was increased. Conclusion: Therefore, it is hope that it will bring new view of powder metallurgy Co-Cr alloy as bio-material

    The sintering temperature effect on the shrinkage behavior of cobalt chromium alloy

    Get PDF
    Problem Statement: Co-Cr based alloys which is well known for its high Young’s modulus, fatigue strength, wear resistance and corrosion resistance is an important metallic bio�material. However, till date there are only two type of Co-Cr alloy which are the castable and wrought cobalt alloy. Powder Metallurgy route for cobalt is expected to give better result of Co-Cr alloy. The purpose of this research was mainly to study the sintering temperature effect to the shrinkage behavior of Cobalt Chromium (Co-Cr) alloy of the powder metallurgy route. Approach: Co-Cr was produced following P/M route under sintering temperature of 1000, 1100, 1200, 1300 and 1400oC. The sintering time was fixed at 60 min. Several tests has been conducted to determine this effect such as the rate of shrinkage measurement, the bulk density and porosity percentage measurement, compression and hardness tests and micro structural study. Result: From the study, it was found that the sintering temperature has caused the shrinkage of Co-Cr. The increasing of the sintering temperature has caused to the increasing of shrinkage of Co-Cr. This has resulted to the reduction of the pore volume and hence increased it density. In conjunction to that, the strength and the hardness of Co-Cr was increased. Conclusion: Therefore, it is hope that it will bring new view of powder metallurgy Co-Cr alloy as bio-material

    Ethnobotanical, phytochemical and pharmacological aspects of daphne mucronata (thymeleaceae)

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    Daphne mucronata is a shrub well known as a medicinal plant in different regions of Asia. Ethnobotanical, phytochemical and pharmacological studies have revealed strong anti-cancer potential of the plant. Literature reports the evaluation of the initial bioactivity profile and extraction of the plant followed by different chromatographic techniques to obtain fractions. As an outcome,  isolation and identification of coumarins, flavonoids, triterpenoids, lignin  cumarinolignans, glucosides, daphnecin, aquillochin, daphnine and umbelliferone from the plant have been reported. Of these compounds, a diterpene, named gnidilatimonoein, has shown promising anticancer potency in in vitro tests on various cancer cell lines. This review article is an effort to summarize literature published in recent years on the bioactivity of Daphne mucronata

    A game theoretic approach for optimizing density of remote radio heads in user centric cloud-based radio access network

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    In this paper, we develop a game theoretic formulation for empowering cloud enabled HetNets with adaptive Self Organizing Network (SON) capabilities. SON capabilities for intelligent and efficient radio resource management is a fundamental design pillar for the emerging 5G cellular networks. The C-RAN system model investigated in this paper consists of ultra-dense remote radio heads (RRHs) overlaid by central baseband units that can be collocated with much less densely deployed overlaying macro base-stations (BSs). It has been recently demonstrated that under a user centric scheduling mechanism, C-RAN inherently manifests the trade-off between Energy Efficiency (EE) and Spectral Efficiency (SE) in terms of RRH density. The key objective of the game theoretic framework developed in this paper is to dynamically optimize the trade-off between the EE and the SE of the C- RAN. More specifically, for an ultra-dense C- RAN based HetNet, the density of active RRHs should be carefully dimensioned to maximize the SE. However, the density of RRHs which maximizes the SE may not necessarily be optimal in terms of the EE. In order to strike a balance between these two performance determinants, we develop a game theoretic formulation by employing a Nash bargaining framework. The two metrics of interest, SE and EE, are modeled as virtual players in a bargaining problem and the Nash bargaining solution for RRH density is determined. In the light of the optimization outcome we evaluate corresponding key performance indicators through numerical results. These results offer insights for a C-RAN designer on how to optimally design a SON mechanism to achieve a desired trade-off level between the SE and the EE in a dynamic fashion

    IK-FA, a new heuristic inverse kinematics solver using firefly algorithm

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    In this paper, a heuristic method based on Firefly Algorithm is proposed for inverse kinematics problems in articulated robotics. The proposal is called, IK-FA. Solving inverse kinematics, IK, consists in finding a set of joint-positions allowing a specific point of the system to achieve a target position. In IK-FA, the Fireflies positions are assumed to be a possible solution for joints elementary motions. For a robotic system with a known forward kinematic model, IK-Fireflies, is used to generate iteratively a set of joint motions, then the forward kinematic model of the system is used to compute the relative Cartesian positions of a specific end-segment, and to compare it to the needed target position. This is a heuristic approach for solving inverse kinematics without computing the inverse model. IK-FA tends to minimize the distance to a target position, the fitness function could be established as the distance between the obtained forward positions and the desired one, it is subject to minimization. In this paper IK-FA is tested over a 3 links articulated planar system, the evaluation is based on statistical analysis of the convergence and the solution quality for 100 tests. The impact of key FA parameters is also investigated with a focus on the impact of the number of fireflies, the impact of the maximum iteration number and also the impact of (a, ß, ¿, d) parameters. For a given set of valuable parameters, the heuristic converges to a static fitness value within a fix maximum number of iterations. IK-FA has a fair convergence time, for the tested configuration, the average was about 2.3394 × 10-3 seconds with a position error fitness around 3.116 × 10-8 for 100 tests. The algorithm showed also evidence of robustness over the target position, since for all conducted tests with a random target position IK-FA achieved a solution with a position error lower or equal to 5.4722 × 10-9.Peer ReviewedPostprint (author's final draft
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