Temperature Dependence Quantum State of Electron in One Dimensional Carbon Nano Tubes and The Expression for Temperature Co-efficient of Resistance in Terms of Quantum State

The Field of Carbon nano tube (CNT) is an promising area of research theoretically as well as experimentally [1],[2]. In fact the band structure of CNT determines its conductivity and in carbon nano tubes the structural pattern affects the conductivity type i.e the conductivity of CNT depends upon how graphene sheet is rolled up. So, CNT can be made to behave as conductor as well as semiconductor [2] It is well established that the samples of single wall carbon nano tubes with an arm chair wrapping have been produced and exhibit metallic behavior with an intrinsic resistivity which increases approximately linearly with temperature over a wide temperature range (see for instance ref.[4]. In this paper the quantized value of electric conductivity [1],[2] is used in an attempt to show theoretically that the quantum state of the electron of the carbon nano tube is directly related to temperature of the CNT as resistivity of CNT depends on quantum state and also found to depend on temperature. Finally, an effort has been made to find an approximatenbsp expression for the temperature co-efficient of resistance of the CNT

Design, fabrication and characterization of field-effect transistors based on two-dimensional materials and their circuit applications

The field of two-dimensional layered materials has witnessed extensive research activities during the past decade, which commenced with the seminal work of isolating graphene from bulk graphite. In addition to providing a rich playground for scientific experiments, graphene has soon become a material of technological interest for many of its fascinating electrical, thermal, mechanical and optical properties. The controllability of carrier density with electric field in graphene, along with very high carrier mobility and saturation velocity, has motivated the use of graphene channel in field-effect devices. Also, the two-dimensional layered materials family has grown very rapidly with the application of the graphene exfoliation technique and many of these elemental and compound materials are considered useful for transistor applications. In this work, various aspects of the use of two-dimensional layered materials for transistor applications were analyzed. Starting with material synthesis, field-effect transistors (FETs) were designed, fabricated and tested for their DC and high frequency performances. Through the detailed electrical and spectroscopic investigations of several processing techniques for enhanced FET performance, numerous insights were obtained into the FET operation and performance bottlenecks. The reduction of charged impurity scattering in graphene FET by Hexamethyldisilazane interaction improved field-effect mobility and reduced residual carrier concentration. This technique was also shown to be promising for other two-dimensional materials based FET. A useful technique for reducing the thickness of black phosphorus flake with oxygen plasma etching was developed. Both back-gated and top-gated FETs were implemented with good performances. Secondary ion mass spectroscopy and x-ray photoelectron spectroscopy revealed vital structural information about layered black phosphorus. Lastly, these exotic materials based FETs were characterized for their high frequency performance, resulting in gigahertz range transit frequency and operated in a variety of important circuit configurations such as frequency multiplier, amplifier, mixer and AM demodulator.Electrical and Computer Engineerin

The Future of Manufacturing Global Value Chains, Smart Specialization and Flexibility!

© 2018, Global Institute of Flexible Systems Management. The future manufacturing and global value chain will be highly dominated by technological and business innovations to cope with the accelerating pace of changes in consumer behaviour and global business environment. This editorial for the special issue “The future of manufacturing: global value chains, smart specialization and flexibility” enriches the topic of future of manufacturing operations and supply chain management literature. In the line with the theme, this special issue publishes five articles that clearly articulate the emerging thematic discussions

Holographic Vitrification

We establish the existence of stable and metastable stationary black hole bound states at finite temperature and chemical potentials in global and planar four-dimensional asymptotically anti-de Sitter space. We determine a number of features of their holographic duals and argue they represent structural glasses. We map out their thermodynamic landscape in the probe approximation, and show their relaxation dynamics exhibits logarithmic aging, with aging rates determined by the distribution of barriers.Comment: 100 pages, 25 figure

Analysis of Six-Phase Interior Permanent Magnet Synchronous Machines for Optimal Parameter Considerations

Understanding the merits of six-phase interior permanent magnet synchronous machines (IP-MSMs) over their three-phase counterparts, this paper analyses the six-phase machine for optimal parameter and performance considerations. Initially, a mathematical model of the six-phase IPMSM is developed employing the dq-axis theory and performance predicted by the model is verified under identical operating conditions with those using a machine designed and tested through finite element analysis (FEA). The developed and verified machine model is then employed to exclusively derive the relation between various machine parameters in order to obtain optimum flux weakening region in the six-phase IPMSM. Thereafter, the equations derived on the basis of maximum torque per ampere (MTPA) control theory are analyzed to understand the effect of various parameters and variables in influencing the machine’s performance in the ‘constant torque’ region and ‘constant power’ region, power output capability, a ratio of reluctance torque to magnet-assisted torque with changes in the stator current vector etc. This is the contribution of this paper

Camera On-boarding for Person Re-identification using Hypothesis Transfer Learning

Most of the existing approaches for person re-identification consider a static setting where the number of cameras in the network is fixed. An interesting direction, which has received little attention, is to explore the dynamic nature of a camera network, where one tries to adapt the existing re-identification models after on-boarding new cameras, with little additional effort. There have been a few recent methods proposed in person re-identification that attempt to address this problem by assuming the labeled data in the existing network is still available while adding new cameras. This is a strong assumption since there may exist some privacy issues for which one may not have access to those data. Rather, based on the fact that it is easy to store the learned re-identifications models, which mitigates any data privacy concern, we develop an efficient model adaptation approach using hypothesis transfer learning that aims to transfer the knowledge using only source models and limited labeled data, but without using any source camera data from the existing network. Our approach minimizes the effect of negative transfer by finding an optimal weighted combination of multiple source models for transferring the knowledge. Extensive experiments on four challenging benchmark datasets with a variable number of cameras well demonstrate the efficacy of our proposed approach over state-of-the-art methods.Comment: Accepted to CVPR 202

Study of PLL less DSGTP System using band-pass filter and APC (active power coefficient) control

This paper represents a study on a grid-tied photovoltaic (PV) system connected to a non-linear load. The system includes a PV array, a boost converter, a voltage source inverter (VSI), and a coupling inductor for grid connection. The maximum power point tracking (MPPT) mechanism based on Perturb and Observe (P&O) method which is used to control the duty ratio of the boost converter. Synchronization is achieved through a second-order band-pass filter instead of a Phase Locked Loop (PLL). However, the non-linear load causes poor current quality, leading to a high Total Harmonic Distortion (THD) in the grid current, which may affect the sinusoidal nature of the grid current and other connected loads. To address the harmonics problem, an Active Power Coefficient (APC) control technique is implemented to control the PV inverter gate pulse. The proposed model has been simulated in Matlab/Simulink, and system output parameters are analysed graphically. The simulation results indicate that the proposed approach maintains the total harmonic distortion (THD) of the grid current below 5% even in changing weather conditions, which satisfies the IEEE 519 standard