Abstract:
High frequency properties of 4H-SiC double drift region (DDR) Mixed Tunnelling Avalanche Transit Time (MITATT) diodes are studied through computer simulation method. It is interesting to observe that the efficiency of SiC (flat) DDR MITATT diode (16%) is more than 4 times that of Si (flat) DDR MITATT diode (3.59%). In addition, a power output of more than 15 times from the SiC MITATT diode compared to the Si MITATT diode is commendable. A reduced noise measure of 17.71 dB from a low-high-low (lo-hi-lo) structure compared to that of 21.5 dB from a flat structure of SiC is indicative of the favourable effect of tunnelling current on the MITATT diode performance.

Abstract:
Noise characteristics of a Read Avalanche diode are analyzed by incorporating the tunneling mechanism of the electron into the avalanche mechanism. Analytical expressions are presented for the mean square noise voltage and noise measure in MITATT (mixed tunneling and avalanche transit time) mode operation. A wide band gap semiconductor (4H-SiC) based MITATT diode is considered to study the effect of tunneling on the noise characteristics and negative conductance. While exhibiting enough potential for 4H-SiC to be used as a terahertz source of power in the MITATT mode, our results record a noise measure of 35.18 dB at a frequency of 1.5 THz.

Abstract:
We study several anisotropic inflationary models and their implications for the observed violation of statistical isotropy in the CMBR data. In two of these models the anisotropy decays very quickly during the inflationary phase of expansion. We explicitly show that these models lead to violation of isotropy only for low l CMBR modes. Our primary aim is to fit the observed alignment of l=2,3 multipoles to the theoretical models. We use two measures, based on the power tensor, which contains information about the alignment of each multipole, to quantify the anisotropy in data. One of the measures uses the dispersion in eigenvalues of the power tensor. We also define another measure which tests the overall correlation between two different multipoles. We perturbatively compute these measures of anisotropy and fix the theoretical parameters by making a best fit to l=2,3 multipoles. We show that some of the models studied are able to consistently explain the observed violation of statistical isotropy.

Abstract:
We study several anisotropic inflationary models and their implications for the observed violation of statistical isotropy in the CMBR data. In two of these models the anisotropy decays very quickly during the inflationary phase of expansion. We explicitly show that these models lead to violation of isotropy only for low l CMBR modes. Our primary aim is to fit the observed alignment of l=2,3 multipoles to the theoretical models. We use two measures, based on the power tensor, which contains information about the alignment of each multipole, to quantify the anisotropy in data. One of the measures uses the dispersion in eigenvalues of the power tensor. We also define another measure which tests the overall correlation between two different multipoles. We perturbatively compute these measures of anisotropy and fix the theoretical parameters by making a best fit to l=2,3 multipoles. We show that some of the models studied are able to consistently explain the observed violation of statistical isotropy.

Abstract:
The fluidization characteristics of fine particles have been studied in both the fluidized bed and spouted bed. The effect of different system parameters (viz. static bed height, particle size, particle density and superficial velocity of the fluidizing medium, rotational speed of stirrer, and spout diameter) on the fluidization characteristics such as bed expansion/fluctuation ratios, bed pressure drop, minimum fluidizing/spouting velocity, and fluidization index of fine particles (around 60 micron particle size) have been analyzed. A stirrer/rod promoter has been used in the bed to improve the bed fluidity for fluidization process and spout diameter has been varied for spouted bed. Mathematical expressions for these bed dynamics have been developed on the basis of dimensionless analysis. Finally calculated values of these bed dynamics are compared with the experimentally observed values thereby indicating the successful applications of these developed correlations over a wide range of parameters. 1. Introduction Fluidization quality is closely related to particle intrinsic properties. The difference between fluidized bed and spouted bed lies in the dynamic behaviours of the solid particles. In a fluidized bed, air is passed through a multiorifice distributor/plate to fluidize the particles. Fluidized bed is divided mainly in two regions; bubble phase and emulsion phase [1] as shown in Figure 1. Figure 1: Different regions of fluidized/spouted bed. Spouted bed is gas-solid contactor in which the gas is introduced through a single orifice from the centre of a flat base, instead of a multiorifice system, resulting in a systematic cyclic pattern of solid movement inside the bed [2] as shown in Figure 1. A spouted bed has three different regions: the annulus, the spout, and the fountain [3, 4]. At stable spouting process, a spout appears at the centre of bed, a fountain appears above the bed surface and an annulus forms between the spout and wall, as shown in Figure 1. At stable spouting process, spout and fountain are similar to fluidized beds where particles are dynamically suspended. On the other hand the annulus region is more like a packed bed. At partial spouting case, there are two distinct regions, an internal spout which is similar to a fluidized bed and the surrounding packed particle region similar to a packed bed. It is observed that spouted bed perform better for defluidization or segregation of particles [5]. As the particle size decreases the cohesive force between the particles increases causing the fluidity of the bed to decrease [1] for

Abstract:
Fluoride, a normal constituent of natural waters has dual significance. At optimum concentration it has a protective effect on teeth. At concentrations exceeding a certain limit, it acts as a cumulative toxin, adversely affecting every tissue and organ in the body. Since water is one of the major sources of fluoride for man, defluoridation of drinking water is one of the most important remedial measures to solve high fluoride problem. Over the years several defluoridation techniques have been developed and put to test, some at the laboratory level and others at the community level. This article attempts to review the procedure, pros and cons of some field studies on water defluoridation done in India.

Abstract:
Putting several existing ideas together, in this paper we define the concept of cyclic coupled Kannan type contraction. We establish a strong coupled fixed point theorem for such mappings. The theorem is supported with an illustrative example. 1. Introduction and Mathematical Preliminaries In this paper, we establish a strong coupled fixed point result by using cyclic coupled Kannan type contractions. The following are two of several reasons why Kannan type mappings feature prominently in metric fixed point theory. They are a class of contractive mappings which are different from Banach contraction and have unique fixed points in complete metric spaces. Unlike the Banach condition, they may be discontinuous functions. Following their appearance in [1, 2], many persons created contractive conditions not requiring continuity of the mappings and established fixed points results of such mappings. Today, this line of research has a vast literature. Another reason for the importance of the Kannan type mapping is that it characterizes completeness which the Banach contraction does not. It has been shown in [3, 4], the necessary existence of fixed points for Kannan type mappings implies that the corresponding metric space is complete. The same is not true with the Banach contractions. In fact, there is an example of an incomplete metric space where every contraction has a fixed point [5]. Kannan type mappings, its generalizations, and extensions in various spaces have been considered in a large number of works some of which are in [6–10] and in references therein. A mapping , where is a metric space, is called a Kannan type mapping if for some (see [1, 2]). Let and be two nonempty subsets of a set . A mapping is cyclic (with respect to and ) if and . The fixed point theory of cyclic contractive mappings has a recent origin. Kirk et al. [11] in 2003 initiated this line of research. This work has been followed by works like those in [12–15]. Cyclic contractive mappings are mappings of which the contraction condition is only satisfied between any two points and with and . The above notion of cyclic mapping is extended to the cases of mappings from to in the following definition. Definition 1. Let and be two nonempty subsets of a given set . We call any function such that if and and if and a cyclic mapping with respect to and . Coupled fixed point problems have a large share in the recent development of the fixed point theory. Some examples of these works are in [16–22] and references therein. The definition of the coupled fixed point is the following. Definition 2

Abstract:
The hemispherical power asymmetry, observed in the CMBR data, has generally been interpreted in terms of the dipole modulation model for the temperature fluctuations. Here we point out that this model leads to several predictions, which can be directly tested in the current data. We suggest tests of the hemispherical power asymmetry both in real and multipole space. We find a significant signal of the dipole modulation model in WMAP and PLANCK data with our tests. The dipole amplitude and direction also agrees, within errors, with earlier results based on hemispherical analysis in multipole space. We also find evidence that the effective dipole modulation amplitude increases with the multipole l in the range l=2-64.

Abstract:
The channel of Bhagirathi River is the branches off from the Ganga at Nurpur (lower course of the Ganga). Bhagirathi River is one of the main rivers in Murshidabad district. Analyzing the image of the Bhagirathi River in Murshidabad district through the year 1970, 1977, 1990, 2000 and 2006, it is found that significant changed has been occurred in souththern part of the river and less change is found in the middle part which is close to the Berhampore town. Toposheet of the year 1970 is also compared with the image data to observe the change. Water discharge, soil types and transportation of sediment is the major contributing factor of morphological changes like bar or shoal, ox-bow Lake, meander etc. Maximum erosion takes place at Dear Balagachi and after Baidyanathpur. A cut-off has take place at Baidyanathpur in 1984 [1]. It is found from the study that there is a possibility of natural meander cut-off at Dear Balagachi and near Majayampur. The traditional bank protection works, concrete walls, cemented stone and brick, play a significant role in the modification of the hydraulic aspect of the discharge values and in the interference in the water dynamics of erosive and depositional phenomena both upstream and downstream.

Abstract:
The reaction of Os(RL1)(PPh3)2(CO)Br, 1b, with qui-nolin-8-ol (HQ), 2, has furnished complexes of the type [Os(RL2)(PPh3)2(CO)(Q)], 3, in excellent yield (RL1 is C6H2O-2-CHNHC6H4R(p)-3-Me-5, RL2 is C6H2OH-2-CHNC6H4R(p)-3-Me-5 and R is Me, OMe, Cl). In this process, quinolin-8-olato (Q) undergoes five-membered chelation, the iminium-phenolato function tautomerizing to the imine-phenol function. The trans geometry of the Os(PPh3)2 fragment is consistent with the occurrence of a single 31P resonance near –6.0 ppm in 3. In dichloromethane solution, 3 displays a quasireversible 3+/3 couple near 0.40 V vs. SCE (3+ is the osmium (III) analogue of 3). Coulometrically generated solutions of 3+ displays a strong absorption near 340 nm, 415 nm and 500 nm and are one-electron paramagnetic (low-spin d5, S = 1/2) and show rhombic EPR spectra in 1:1 dichloromethanetoluene solution at 77 K with g values near 2.44, 2.20, 1.83. Distortion parameters using the observed g values have been computed. Solutions of 3 absorb near 420 nm and emit near 510 nm at 298 K and 580 nm at 77 K. The fluorescence is believed to originate from the 3MLCT state.