Dynamics of growth and weight transitions in a pediatric cohort from India

Background  

There is paucity of information regarding time trends of weight status in children from rapidly developing economies like India. The aim of the study was to analyse the dynamics of growth and weight transitions in a cohort of school children from India.     

An Unconstrained Architecture for Systematic Design of Higher Order $SigmaDelta$ Force-Feedback Loops

Nowadays, $SigmaDelta$ -modulation is a widely used technique for analog-to-digital (A/D) conversion, especially when aiming for high resolutions. While being applied initially for purely electrical A/D converters, its application has been expanded to mixed mechanical–electrical systems. This has led to the use of $SigmaDelta$ force-feedback for digital readout of high-performance inertial sensors. However, compared with their electrical counterpoint, $SigmaDelta$ force-feedback loops often have to deal with three additional issues: 1) an increased stability problem due to phase-lag occurring in the sensor; 2) the injection of relatively high levels of readout noise in the loop; and 3) the lack of degrees-of-freedom of many $SigmaDelta$ force-feedback architectures for implementing an arbitrary noise transfer function. As a result, $SigmaDelta$ force-feedback loops found in literature are designed in a much less systematic way as compared with electrical $SigmaDelta$ modulators. In this paper, we address these issues and propose a new unconstrained architecture. Based on this architecture, we are able to present a systematic approach for designing $SigmaDelta$ force-feedback loops. Additionally, the main strengths and weaknesses of different $SigmaDelta$ force-feedback architectures are discussed.      

Optimal NC path planning: is it really possible?

NC physical verification effort can be considerably reduced by analytical modelling of NC tool path. A computer algorithm was developed to graphically emulate the tool path while machining flat polygonal objects. The orientation of the cutter center line relative to the object was then varied and several configurations were generated. For each configuration the total path was evaluated and plotted. Nature of the plots showed that an analytical optimization of the path is possible. In order to make the model more rigorous, attempts are being made to include the effects of the cutter tool life on the total path.     

Life cycle cost analysis of HPVT air collector under different Indian climatic conditions

In this communication, a study is carried out to evaluate an annual thermal and exergy efficiency of a hybrid photovoltaic thermal (HPVT) air collector for different Indian climate conditions, of Srinagar, Mumbai, Jodhpur, New Delhi and Banglore. The study has been based on electrical, thermal and exergy output of the HPVT air collector. Further, the life cycle analysis in terms of cost/kWh has been carried out. The main focus of the study is to see the effect of interest rate, life of the HPVT air collector, subsidy, etc. on the cost/kWh HPVT air collector. A comparison is made keeping in view the energy matrices. The study reveals that (i) annual thermal and electrical efficiency decreases with increase in solar radiation and (ii) the cost/kWh is higher in case of exergy when compared with cost/kWh on the basis of thermal energy for all climate conditions. The cost/kWh for climate conditions of Jodhpur is most economical.     

The relationship between activation energy and precipitate size for precipitate agglomeration

Superalloys are used in aggressive atmospheres in aero-engines and land-base gas turbines. IN738LC is an important superalloy used in gas turbines. Strengthening Ni₃(Al,Ti,Nb) type precipitate phase in this superalloy goes through size and morphological changes with time and temperature. Experimental observations suggest precipitate motion as a whole in the matrix leading to agglomeration of nearby precipitates for coarsening, which is in contrast to the traditional Ostwald ripening. Likewise, contrary to the conventionally accepted view of constant activation energy, experimental data in this study indicate varying activation energy, which causes coalescence and relates to the precipitate size in the form of an increasing polynomial.     

ITP: an image transport protocol for the Internet

Images account for a significant and growing fraction of Web downloads. The traditional approach to transporting images uses TCP, but this is overly restrictive for image data. Our analysis shows that the in-order delivery abstraction provided by a TCP-based approach prevents the receiver application from processing and rendering portions of an image when they actually arrive. Thus an image is rendered in bursts interspersed with long idle times rather than smoothly. This paper describes the design, implementation and evaluation of an image transport protocol (ITP) for image transmission over loss-prone congested or wireless networks. ITP improves user-perceived latency using application-level framing (ALF) and out-of-order application data unit (ADU) delivery, achieving significantly better interactive performance as measured by the evolution of peak signal-to-noise ratio (PSNR) with time at the receiver. ITP runs over UDP, incorporates receiver-driven selective reliability, uses a congestion manager (CM) to adapt to network congestion and is customizable for specific image formats (e.g., JPEG and JPEG2000). ITP enables a variety of new receiver post-processing algorithms such as error concealment that further improve the interactivity and responsiveness of reconstructed images. Performance experiments across a variety of loss conditions demonstrate the benefits of ITP in improving the interactivity of image downloads at the receiver     

Mathematical tolerance verification of N-sided prisms using Fourier analysis

The tolerance evaluation of complex forms including prisms has not been studied at any length in literature. This paper investigates the possibility of applying a model that uses Fourier series analysis to verify the form in prisms. In doing so, two unique features are highlighted: the study of prisms for form evaluation, and the application of Fourier methods for form metrology. Experimentation on square, rectangular, and hexagonal prisms was conducted to determine the efficiency of the model. The model was analyzed applying 10,000 harmonics that were used to compare the values of the measured prism against the proposed model. Results from this experiment show that the model is consistent when measuring prisms at different sample sizes.     

Focus-engineered coherent anti-Stokes Raman scattering microscopy: a numerical investigation

The coherent anti-Stokes Raman scattering (CARS) signal is calculated as a function of focal-field distributions with engineered phase jumps. We show that the focal fields in CARS microscopy can be shaped such that the signal from the bulk is suppressed in the forward detection mode. We present the field distributions that display enhanced sensitivity to vibrationally resonant object interfaces in the lateral dimension. The use of focus-engineered CARS provides a simple means to detect chemical edges against the strong background signals from the bulk.     

Topological Quantum Phase Transition and Superconductivity Induced by Pressure in the Bismuth Tellurohalide BiTeI

A pressure‐induced topological quantum phase transition has been theoretically predicted for the semiconductor bismuth tellurohalide BiTeI with giant Rashba spin splitting. In this work, evolution of the electrical transport properties in BiTeI and BiTeBr is investigated under high pressure. The pressure‐dependent resistivity in a wide temperature range passes through a minimum at around 3 GPa, indicating the predicted topological quantum phase transition in BiTeI. Superconductivity is observed in both BiTeI and BiTeBr, while resistivity at higher temperatures still exhibits semiconducting behavior. Theoretical calculations suggest that superconductivity may develop from the multivalley semiconductor phase. The superconducting transition temperature, T_c, increases with applied pressure and reaches a maximum value of 5.2 K at 23.5 GPa for BiTeI (4.8 K at 31.7 GPa for BiTeBr), followed by a slow decrease. The results demonstrate that BiTeX (X = I, Br) compounds with nontrivial topology of electronic states display new ground states upon compression.