Akash I. Mecwan

Design implementation of high performance DC motor drive.

DC Motors are quite common in large number of applications ranging from small tools to large industrial machines. Efficiency of such machines depends on proper operation of these motors to a much larger extent. Moreover, heavy duty applications require high current demanding motors. High current also leads to addition of other noise issues. Here we put forward a high performance motor drive circuit tested for heavy duty applications demanding DC currents up to 200 A where switching of motors was done at 32KHz to remove the switching noise. The usage of dynamic switching frequency is represented here which enables us to achieve higher duty cycles up to 99.6% which is not possible with static switching frequencies in absence of charge pump. The drive circuit having dimensions 5cm×5cm has been tested for extreme load and noise conditions and several protection measures implemented in this circuit are described here.

Voice conversion algorithm

Recently, a lot of work has been done in the speech technology. The main concentration being on Text-to-speech and automatic speech recognition techniques, voice conversion is yet an undeveloped and naïve field in Speech Technology and a lot of contribution from speech researchers is expected in upcoming days. In this paper an approach for static voice conversion is discussed. Static speech parameters are the parameters over which speaker has least control such as vocal tract structure, natural pitch of speech etc. Here, two main parameters are considered Vocal Tract Structure and Pitch. For conversion process speech is resolved in two components, excitation component and filtered component using a Linear Predictive coding [LPC] based source-filter. The pitch contour is determined by an autocorrelation. The excitation component is generated using a set of signal generators generating the determined pitch and are driven by voicing detection. Filter coefficients are modified to approach target speaker coefficients for voiced segments and for unvoiced segments filter coefficients of source are used straightaway.

Proportionally distributed resource allocation in small-cell networks

Efficient resource allocation is one of the most challenging facet in small cell deployment. With continuous research, many algorithms have been developed in this regard. The proposed algorithm is for small cell downlink on a large scale with the context of orthogonal frequency division multiple access. The proposed algorithm has 4 stages, one of which also incorporates device-to-device (D2D) communication inside a small cell. The algorithm uses distributed resource allocation for downlink model based on user demand. A simulation environment is developed to study the quantitative effects of proposed algorithm. Poisson random distribution is used to model the user and access point locations. The interference analysis to determine maximum distance of D2D connection within a small cell is also provided. Performance comparisons between fixed resource allocation, partially distributed allocation and the proposed, proportional resource allocation algorithm with and without D2D are also shown. The simulations are carried out in MATLAB 2013.

Linearity improvement of LNA using Derivative Superposition: Issues and challenges

LNA being the first block of all RF receiver systems, demands very large gain and low noise with high linearity. Lots of techniques are available to increase the gain and reduce the noise contribution of LNA. Linearity of LNA has started grabbing attention of researchers as transistor size reduces and frequency of operation goes to the microwave range. Traditional techniques of linearity improvement may not work with higher gain requirements. Derivative Superposition (DS) is one of the new methods, which seems promising for the improvement in Linearity of LNA. The paper covers the concept of DS. The issues with the simple DS method are discussed and possible improvements in the design are suggested. The challenges for each design are also presented. LNA designs using DS with possible variations are implemented and compared for Gain, Power requirement and Linearity.

Innovations in evaluation: An integral part of outcome based education

Education in India in 21st century demands innovations in the evaluation methods with the emergence of Outcome Based Education (OBE). Lots of Research is already done in innovations in teaching and learning methods, but very few literatures on the innovations in evaluations are available. The paper discusses various innovative methods for the evaluation of students. The pros and cones of traditional exam and the new methods are also discussed. A survey on the various method is carried out and the results of the same are also presented.