Design and Implementation of Position Estimator Algorithm on Voice Coil Motor

Voice Coil Motors (VCMs) have been an inevitable element in the mechanisms that have been used for precise positioning in the applications like 3D printing., micro-stereolithography., etc. These voice coil motors translate in a linear direction and require a high accuracy position sensor that amounts for a major part in the budget. In this research work., an effort has been made to design and implement an algorithm that would predict the displacement of VCM and eliminate the need of high cost sensors. VCM was integrated with dSPACE DS1104 R&D controller via linear current amplifier (LCAM) which acts as a driver circuit for VCM. Sine input was given to VCM with various amplitude and frequency and the corresponding displacement is measured by using linear variable differential transformer (LVDT). The position estimator algorithm is also implemented at the same time on VCM and its output is compared with that of LVDT. It is observed that there is 97.8 % accuracy in between algorithm output and LVDT output. Further., PID controller is used in integration with the novel algorithm to minimize the error. The estimator algorithm is tested for various amplitudes and frequencies and it is found that it has a very good agreement of 99.2% with the actual displacement measured with the help of LVDT

A Critical Review On Blepharitis And Its Ayurvedic Approach

Blepharitis is a common eye condition characterized by inflammation of the eyelid  margins resulting in inflamed, irritated, itchy, reddened and oedematous eyelids. A number of diseases and conditions can lead to blepharitis. It can be caused by the oil glands at the base of the eyelashes becoming clogged due to  bacterial infection, allergies or other conditions. The severity and course can vary. Blepharitis is a long-standing chronic granulomatous inflammation of lid margins.American Optometric Association has concluded that if blepharitis left untreated it can cause more serious conditions such as scarring or injury to the eye tissue or also lead to dry eye syndrome.Also,some cases of blepharitis may require more complex treatment plans and even with the successful treatment recurrence may occur4.Blepharitis can be correlated with the sign and symptoms of Praklinna vartma which is breifly explained in vartmagat netravyadhis in Sushrut samhita.According to the Tridosh siddhant of Ayurveda blepharitis is a kaphaj vyadhi. Ayurvedic preparations for local application like Triphala rasakriya varti,Apamarga rasakriya varti,Vanshmool raskriya varti,Palash pushp raskriya varti are explained by Sushrutacharya in the treatment of praklinna vartma5

Multi-objective optimization of TW-ECSM process parameters for machining of advanced non-conducting material

52-61Travelling wire electrochemical spark machining (TW-ECSM) is newly evolved and developed hybrid machining process for the machining of advanced non-conducting materials which possess significant values of the properties like high strength, high wear and fatigue resistance, high refractoriness and high strength to weight ratio, etc. The control parameters like voltage, wire feed rate, electrolyte concentration and inter-electrode gap were selected as Input Parameters and Material Removal Rate (MRR), and Surface Roughness (SR) were the corresponding output responses. In present work, for multiobjective optimization and purpose of better control of machining parameters, three approaches, grey-relational analysisprincipal component analysis (GRA-PCA), fuzzy logic and desirability function approach are used to determine the optimal combination of TW-ECSM process variables. Results of fuzzy logic and GRA-PCA approach are found comparable while desirability function approach is found to be capable of predicting the optimal responses at such levels of process variables also at which experiments are not performed. Consequences of the applied approach in the present work are also validated by conducting the confirmatory experiments and results are found in well agreement with the predicted results

Characterization and System Identification of XY Flexural Mechanism Using Double Parallelogram Manipulator for High Precision Scanning

This article represents modeling of double parallelogram flexural manipulator derived from basic classical mechanics theory. Fourth order vibration wave equation is used for mathematical modeling and its performance is determined for step input and sinusoidal forced input. Static characterization of DFM is carried out to determine stiffness and force deflection characteristics over the entire motion range and dynamic characteristics is carried out using Transient response and Frequency response. Transient response is determined using step input to DFM which gives system properties such as damping, rise time and settling time. These parameters are then compared with theoretical model presented previously. Frequency response of DFM system gives characteristics of system with different frequency inputs which is used for experimental modeling of DFM device. Here, Voice Coil Motor is used as Actuator and optical encoder is used for positioning sensing of motion stage. It is noted that theoretical model is having 5% accuracy with experimental results. To achieve better position and accuracy, PID and LQR (Linear Quadratic Regulator) implementation was carried out on experimental model. PID gains are optimally tuned by using Ziegler Nichols approach. PID control is implemented experimentally using dSPACE DS1104 microcontroller and Control Desk software. Experimentally, it is observed that positioning accuracy is less than 5 μm. Further multiple DFM blocks are arranged for developing XY flexural mechanism and static characterization was carried out on it. The comparison of experimental and FEA results for X-direction and Y-direction is presented at end of paper

Foley catheter vs. oral misoprostol to induce labour among hypertensive women in India: a cost-consequence analysis alongside a clinical trial

ObjectiveTo determine the effectiveness and economic impact oftwo methods for induction of labour in hypertensive women, inlow-resource settings.DesignCost-consequence analysis of a previously reportedmulticentre, parallel, open-label randomised trial.Setting & populationA total of 602 women with a live fetus, aged≥18 years requiring delivery for pre-eclampsia or hypertension, intwo public hospitals in Nagpur, India.MethodsWe performed a formal economic evaluation alongsidethe INFORM clinical trial. Women were randomised to receivetranscervical Foley catheterisation or oral misoprostol 25 mcg.Healthcare expenditure was calculated using a provider-sidemicrocosting approach.Main outcome measuresRates of vaginal this delivery within24 hours of induction, healthcare expenditure per completedtreatment episode.ResultsInduction with oral misoprostol resulted in a (meandifference) $20.6USD reduction in healthcare expenditure [95$123.59 ( ) $72.49], and improved achievement ofvaginal delivery within 24 hours of induction, mean difference10$0.24 to $7.50 per 25 mcg tablet and remain cost-saving

CVD growth of carbon nanostructures from zirconia: mechanisms and a method for enhancing yield.

By excluding metals from synthesis, growth of carbon nanostructures via unreduced oxide nanoparticle catalysts offers wide technological potential. We report new observations of the mechanisms underlying chemical vapor deposition (CVD) growth of fibrous carbon nanostructures from zirconia nanoparticles. Transmission electron microscope (TEM) observation reveals distinct differences in morphological features of carbon nanotubes and nanofibers (CNTs and CNFs) grown from zirconia nanoparticle catalysts versus typical oxide-supported metal nanoparticle catalysts. Nanofibers borne from zirconia lack an observable graphitic cage consistently found with nanotube-bearing metal nanoparticle catalysts. We observe two distinct growth modalities for zirconia: (1) turbostratic CNTs 2-3 times smaller in diameter than the nanoparticle localized at a nanoparticle corner, and (2) nonhollow CNFs with approximately the same diameter as the nanoparticle. Unlike metal nanoparticle catalysts, zirconia-based growth should proceed via surface-bound kinetics, and we propose a growth model where initiation occurs at nanoparticle corners. Utilizing these mechanistic insights, we further demonstrate that preannealing of zirconia nanoparticles with a solid-state amorphous carbon substrate enhances growth yield.This material is based upon work supported by the National Science Foundation under Grant No. 1007793 and was also supported by Airbus group, Boeing, Embraer, Lockheed Martin, Saab AB, Hexcel, and TohoTenax through MIT’s Nano- Engineered Composite aerospace STructures (NECST) Consortium. This research was supported (in part) by the U.S. Army Research Office under Contract W911NF-13-D-0001. This work was performed in part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF Award No. ECS-0335765. CNS is part of Harvard University. This work was carried out in part through the use of MIT Microsystems Technology Laboratories. Stephan Hofmann acknowledges funding from EPSRC under grant EP/H047565/1. Piran Kidambi acknowledges the Lindemann Trust Fellowship.This is the final published version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/ja509872y

Bone marrow-derived cells in ocular neovascularization: contribution and mechanisms

Ocular neovascularization often leads to severe vision loss. The role of bone marrow-derived cells (BMCs) in the development of ocular neovascularization, and its significance, is increasingly being recognized. In this review, we discuss their contribution and the potential mechanisms that mediate the effect of BMCs on the progression of ocular neovascularization. The sequence of events by which BMCs participate in ocular neovascularization can be roughly divided into four phases, i.e., mobilization, migration, adhesion and differentiation. This process is delicately regulated and liable to be affected by multiple factors. Cytokines such as vascular endothelial growth factor, granulocyte colony-stimulating factor and erythropoietin are involved in the mobilization of BMCs. Studies have also demonstrated a key role of cytokines such as stromal cell-derived factor-1, tumor necrosis factor-α, as well as vascular endothelial growth factor, in regulating the migration of BMCs. The adhesion of BMCs is mainly regulated by vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and vascular endothelial cadherin. However, the mechanisms regulating the differentiation of BMCs are largely unknown at present. In addition, BMCs secrete cytokines that interact with the microenvironment of ocular neovascularization; their contribution to ocular neovascularization, especially choroidal neovascularization, can be aggravated by several risk factors. An extensive regulatory network is thought to modulate the role of BMCs in the development of ocular neovascularization. A comprehensive understanding of the involved mechanisms will help in the development of novel therapeutic strategies related to BMCs. In this review, we have limited the discussion to the recent progress in this field, especially the research conducted at our laboratory