Analytical modeling of Junctionless Accumulation Mode Cylindrical Surrounding Gate MOSFET (JAM‐CSG)

This paper presents physics based analytical model for center potential, electric field and subthreshold drain current of Junctionless Accumulation Mode Cylindrical Surrounding Gate MOSFET (JAM‐CSG). The expressions are derived from Poisson's equation in cylindrical co‐ordinate system based on parabolic potential approximation (PPA). The influence of technology parameter variations such as gate length, silicon pillar diameter and oxide thickness on electrical characteristics is studied in detail. Developed analytical model results are validated through the good agreement with simulated data obtained from ATLAS 3D simulator. Copyright © 2016 John Wiley & Sons, Ltd.     

Evaluation and optimisation of receiver height in a compound parabolic collector with low acceptance angle

This research presents the method of finding an optimised location of a tubular receiver for a compound parabolic collector (CPC) with 6° acceptance angle. Due to low acceptance angle, reflected rays concentrate below the focus of a parabola. Graphical ray tracing (GRT) approach is implemented to execute the optical analysis with and without manufacturing error in the collector. It is performed on collector–receiver combinations by varying receiver height below the focus and they are compared on the basis of utilised area and projection ratios. The ideal cases of collector–receiver combinations which contribute high utilisation and projection ratio are selected and verified with the camera target method (CTM) performed on the actual set-up. It is built for water heater application to validate the results obtained from GRT and CTM. The thermal performance of CPC at various receiver heights is compared by thermal efficiency and therefore the optimum receiver height is concluded.     

Aminosilane densities on nanotextured silicon

Aminosilanization of hydroxylated surfaces is used for attachment of biomolecules which have various applications. The density of the surface amine group is of importance as it determines the density of the subsequent immobilized or self-assembled molecules over the aminosilylated layer; hence there is a need to understand the processes and the phenomena that control the surface aminosilane density. Crystalline silicon surfaces, nanotextured using the HF/HNO₃/H₂O chemistry, were silanized using aminosilanes (APTES and APTMS). Masks were not used to obtain the surface topography; rather the surface textures (< 100 nm RMS roughness) were controlled by process conditions such as temperature, etchant composition and etch time. The aminosilane densities were dependent on the surface texture and composition. Our results showed that oxidation of the surface resulted in lower silane densities. While increased surface area enhanced the densities, processes like the HNO₃-rich chemistries while increasing the surface area were also associated with surface oxidation resulting in lower densities compared to surfaces textured with HF-rich compositions.     

Structural,dielectric, impedance and ferroelectric properties of lead-free Bi(Fe0.85Dy0.15)O3 ceramic

Nowadays, several research groups are extensively trying to develop by synthesizing and characterizing single/co-doped single-phase bismuth ferrite (BFO) in order to get a highly efficient eco-friendly multifunctional devices. In this process, this report is an attempt to provide the detailed studies of structural, dielectric, impedance and ferroelectric properties of Bi(Fe_0.85Dy_0.15)O₃ ceramic fabricated via the solid-state reaction method. Analysis of X-ray diffraction (XRD) data confirms a single phase of orthorhombic symmetry. The average crystallite (particle) size is found to be in the order of?~?41 nm. The field emission scanning electron microscopy (FE-SEM) spectrum shows a homogeneous grain distribution of the sample. The elemental composition examined by means of energy dispersive X-ray spectroscopy (EDXS) shows the existence of constituent elements of the sample. The electrical measurements and analysis, carried out using a computer-controlled phase sensitive multimeter (PSM) in a frequency range of 1 kHz–1 MHz at different sets of temperature (25–325 °C), provide many interesting features to explain further conduction mechanism. The dielectric analysis exhibits high value of dielectric constant (?_r) and small value of dielectric loss (tanδ). Due to the effect of electronic and space charge polarization, the ?_r value falls with an increasing frequency. The frequency–temperature dependence of impedance and electrical modulus analysis reveals the presence of semiconductor nature and non-Debye type of relaxation process in the sample. The analysis of ac-conductivity (σ_ac) with respect to frequency and temperature obeys the universal Jonscher’s power law. The electric polarization study shows an enhancement in ferroelectric property of the material. Hence, based on the significant enhancement in electrical and ferroelectric properties of the Bi(Fe_0.85Dy_0.15)O₃ material, the material may be considered for some applications.

     

Response Time in Data Broadcast Systems: Mean,Variance and Tradeoff

Data broadcast has been suggested as a promising method of information dissemination [2,33]. In such an environment, the information server cannot afford to serve the requests from a large population of users individually. Instead, the server uses a broadcast channel to deliver information to all users. A single transmission of a data item satisfies all pending requests for that item. The response time of a request depends on the broadcast time of the desired data item, which is scheduled by the server according to the overall demands for various data items. Therefore, the response time may vary in a large range. We argue that, in addition to mean response time, the variance of response time should also be taken into account by the broadcast scheduler. In this paper, we address the issue of variance optimization in regard to response time. Building on our previous research on mean response time optimization, we propose an algorithm which can minimize the variance of response time. Furthermore, we evaluate an algorithm that facilitates a tradeoff between the mean and variance of response time. Numerical examples that illustrate the performance of our algorithms are also presented.     

Hierarchical Delay Test Generation

Delay testing is used to detect timing errors in a digital circuit.In this paper, we report a tool called MODET forautomatic test generation for path delay faults in modular combinational circuits. Our technique usesprecomputed robust delay tests for individual modules to computerobust delay tests for the module-level circuit. We present alongest path theorem at the module level ofabstraction which specifies the requirements for path selectionduring delay testing. Based on this theorem, we propose a pathselection procedure in module-level circuits and report efficientalgorithms for delay test generation. MODET hasbeen tested against a number of hierarchical circuits with impressivespeedups in relation to gate-level test generation.     

Multiwall carbon-nanotube-doped ion conducting polymer electrolyte for electrochemical application

Electrical, structural and optical properties of a composite containing a polymer electrolyte (namely polyethylene oxide complexed with sodium iodide) and multiwall carbon nanotube (MWCNT) are reported. The films of these composites were ‘solution casted’ using the viscous solution of polyethylene oxide (PEO) complexed with sodium iodide (NaI) in desired ratios and characterised using various techniques. The conductivity versus composition plot in PEO:NaI shows conductivity maxima at 12?wt% NaI concentration while in MWCNTs doped polymer electrolyte it occurs at 40?wt% MWCNTs concentration. The surface morphology by scanning electron microscopy (SEM) shows the enhancement in amorphous reason by MWCNTs doping which is a well-known favourable condition for conductivity enhancement. The differential scanning calorimetry shows that dispersal of MWCNTs reduces the crystallinity of polymer electrolyte that is well-supported by our polarised optical micrographs and SEM measurements.     

User perception study for performance evaluation of domestic defluoridation techniques for its application in rural areas

Fluoride concentrations in ground water have been monitored in rural areas of Dhar and Jhabua districts in Madhya Pradesh, India. A correlation of fluoride concentration with pH, TDS and conductivity has been estimated to identify surrogate monitoring parameter. Further, fluoride removal from drinking water has been achieved by using adsorbents specially developed for domestic applications. These adsorbents have been evaluated using three different methods namely; loose adsorbent, pre-packed sachet and packed bamboo column. Comparative evaluation of these methods has been demonstrated in the laboratory and field. The stringent limit of 1mg/L for fluoride concentration in drinking water has been achieved by use of specially designed adsorbents. A feedback from end-users in Tarapur and Ukala villages of Dhar districts Madhya Pradesh regarding the adsorbents and its acceptability has been collected. User's perception regarding these household treatments reveals encouraging response for defluoridation methods. According to user's perception loose adsorbent approach emerged out as most simple, clean and safe household defluoridation method.     

Image analysis of microstructural changes in almond cotyledon as a result of processing

Release of oil from nuts due to damaged cellular structures can degrade the quality of products incorporating nuts. The aim of this study was to investigate the effects of different processing conditions on microstructure of almond tissue and to quantify these changes using image processing. Spinning disk confocal fluorescence microscopy was used for imaging changes in microstructure of almonds as a function of different thermal processing of almonds. Multiple staining of Nile Red and Calcofluor White was applied to differentiate cell wall structures and oil bodies within individual almond cells without chemical fixation. An algorithm for image processing, included image preprocessing, segmentation, and determination of morphological features of segmented objects, was developed. Oil-roasting processes (140 °C and 150 °C) were found to have a significant impact on microstructure of almonds when compared to the hot air-roasting and blanching processes. Oil-roasted almond at 150 °C had a greater cellular damage due to cell wall and membrane rupture. These changes in microstructure of almonds would make them slightly more susceptible to release oil during storage. The image analysis presented allows quantitative evaluation for the effect of different processing on almond microstructure.     

On the use of NSGA-II for multi-objective resource allocation in MIMO-OFDMA systems

This paper investigates the problem of dynamic subcarrier and bit allocation in downlink of Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiple Access (OFDMA) Systems. Using Singular Value Decomposition, the MIMO fading channel of each subcarrier is transformed into an equivalent bank of parallel Single Input Single Output sub-channels. To achieve the capacity bound, one must solve a multiuser subcarrier allocation and the optimal bit allocation jointly. To alleviate the computational complexity of joint subcarrier and bit allocation, several suboptimal solutions have been proposed. These suboptimal solutions handle subcarrier and bits individually. We propose the use of Non-dominated Sorting Genetic Algorithm (NSGA)-II, which is a multi-objective Genetic Algorithm, for joint allocation of bits and subcarriers, in the downlink of MIMO-OFDMA system. NSGA-II is intended for optimization problems involving multiple conflicting objectives. Here the two conflicting objectives are Rate Maximization and Transmit Power Minimization. The simulation results indicate remarkable improvement in terms of convergence over previous approaches involving Evolutionary algorithms. At the same time capacity achieved by the proposed algorithm is found to be comparable with that of previous algorithms.