Analytical Model of Inverted Multiwick Solar Still

In this communication, new designs of inverted multiwick and tubular multiwick solar stills are discussed. The analysis of both new designs of solar still are presented. Comparisons are also made between the performance of the proposed design and conventional multiwick solar still. It is concluded that inverted multiwick solar still gives about 20% better performance than conventional multiwick solar still.     

High resolution X-ray diffraction studies on unirradiated and irradiated strontium hexaferrite crystals

High-resolution X-ray diffraction technique, employing a three-crystal monochromator?Ccollimator combination is used to study the irradiation induced defects in flux grown Sr-hexaferrite crystals irradiated with 50?MeV Li³⁺ ion beams at room temperature with a fluence value of 1 × 10¹⁴ ions/cm². The diffraction curves of the irradiated crystals suggest the possibility of creation of low angle grain boundaries and other point/clusters of defects causing amorphization in the irradiated crystals. The perfection of the irradiated and unirradiated (0001) cleaved surfaces of the crystals is studied using the bulk method of X-ray topography. The topographs supplement the findings suggestive of modifications in the crystalline quality of SrFe₁₂O₁₉ on irradiation with SHI of Li^3?+?. Etching of the (0001) cleaved surfaces in H₃PO₄ at 120°C suggests that the dissolution characteristics of the surfaces get affected on irradiation with SHI of Li^3?+?, besides supporting the findings of HRXRD and X-ray topography regarding modifications in the perfection of SrFe₁₂O₁₉ on irradiation.     

Influence of pH on ZnO nanocrystalline thin films prepared by sol–gel dip coating method

ZnO nanocrystalline thin films have been prepared on glass substrates by sol?Cgel dip coating method. ZnO thin films have been coated at room temperature and at four different pH values of 4, 6, 8 and 10. The X-ray diffraction pattern showed that ZnO nanocrystalline thin films are of hexagonal structure and the grain size was found to be in the range of 25?C45?nm. Scanning electron microscopic images show that the surface morphology improves with increase of pH values. TEM analysis reveals formation of ZnO nanocrystalline with an average grain size of 44?nm. The compositional analysis results show that Zn and O are present in the sample. Optical band studies show that the films are highly transparent and exhibit a direct bandgap. The bandgap has been found to lie in the range of 3 $\boldsymbol\cdot$ 14?C3 $\boldsymbol\cdot$ 32?eV depending on pH suggesting the formation of ZnO nanocrystalline thin films.     

Barrier characteristics of Pt/Ru Schottky contacts on <Emphasis Type="Italic">n</Emphasis>-type GaN based on <Emphasis Type="Italic">I–V–T</Emphasis> and <Emphasis Type="Italic">C–V–T</Emphasis> measurements

We have investigated the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Ru/Pt/n-GaN Schottky diodes in the temperature range 100–420 K. The calculated values of barrier height and ideality factor for the Ru/Pt/n-GaN Schottky diode are 0·73 eV and 1·4 at 420 K, 0·18 eV and 4·2 at 100 K, respectively. The zero-bias barrier height (Φ_b0) calculated from I–V characteristics is found to be increased and the ideality factor (n) decreased with increasing temperature. Such a behaviour of Φ_b0 and n is attributed to Schottky barrier (SB) inhomogeneities by assuming a Gaussian distribution (GD) of barrier heights (BHs) at the metal/semiconductor interface. The current–voltage–temperature (I–V–T) characteristics of the Ru/Pt/n-GaN Schottky diode have shown a double Gaussian distribution having mean barrier heights ( [`(F)]<sub>\textb0</sub> {\bar{{\Phi}}_{\text{b}0}} ) of 1·001 eV and 0·4701 eV and standard deviations (σ <sub>0</sub>) of 0·1491 V and 0·0708 V, respectively. The modified ln (J<sub>0</sub> /T<sup>2</sup> )-( q<sup>2</sup>s <sub>0</sub><sup>2</sup>/2k<sup>2</sup>T<sup>2</sup> ){ln} ({{J}_{0} /{T}^{2}} )-( {{q}^{2}{\sigma} _{0}^{2}/{2}{k}^{2}{T}^{2}} ) vs 10<sup>3</sup>/T plot gives [`(F)]_\textb0 \bar{{\Phi}}_{\text{b}0} and Richardson constant values as 0·99 eV and 0·47 eV, and 27·83 and 10·29 A/cm²K², respectively without using the temperature coefficient of the barrier height. The difference between the apparent barrier heights (BHs) evaluated from the I–V and C–V methods has been attributed to the existence of Schottky barrier height inhomogeneities.     

Development, characterization, sintering, dielectric and optical properties of NdBa2ZrO5·5 nanocrystals

Nanocrystalline NdBa₂ZrO_{5 ·5} has been successfully synthesized through a single step auto-ignition combustion route for the first time. X-ray diffraction and Fourier transform infrared spectroscopy revealed that the combustion product is phase pure and has an ordered cubic perovskite structure. The phase transitions and thermal stability of the nanopowder were investigated by differential thermal and thermogravimetric analyses. Transmission electron microscopy results indicated that the particle sizes are 20–30 nm. Selected area electron diffraction pattern has shown that as-prepared powder is polycrystalline in nature. The optical absorption spectra analysis confirmed that the material falls to the semiconducting range with a bandgap of ~3 ·69 eV and therefore, could be used as transparent wide bandgap semiconductor. The relative density of the sintered sample is ~96% at 1510 °C for 2 h. The surface morphology of the sintered pellet has been studied by scanning electron microscopy and the average grain size observed is ~0·7  $\upmu$ m. Dielectric constant (ε _r) of NdBa₂ZrO_5·5 at 5 MHz is 29·6 and loss factor (tan δ) is 4 ×10^???2 at room temperature.     

无线传感网络中使用动态代理的节点收敛算法

This paper proposes fault tolerant algorithms for routing mobile agents in a single channel wireless sensor network which cover every node in the network. These algorithms use local knowledge (assume no knowledge of global deployment or topology, etc). We propose the algorithms and show mathematical analysis to support our claims. The paper ends with simulation studies and discussion of results.     

Synthesis and 980°C Phase Development of Some Mullite Gels

Earlier works of mullitization through the gel route have been reviewed and the results show 980°C DTA and crystalline phases. Some Al₂O₃-SiO₂ gels have been synthesized by using different precursors and by varying pH and water content during the gelification process. Thermal changes of these coherent gels were studied by DTA and X-ray powder diffractometry. The results demonstrate that two types of aluminosilicate gels form. The first type produces orthorhombic mullite directly on heating at 980°C, whereas the second type forms cubic mullite first at 980°C and then transforms to the orthorhombic variety on further heating. Lastly, the cause of the 980°C exotherm is explained with reference to kaolinite.     

OBJECTIVE TESTS FOR THE STICKINESS OF COOKED RICE

The suitability of a sieve test and an adhesion test as objective tests for determining the stickiness of cooked rice was examined. Six rice varieties, two each from dwarf incica, tall indica and japonica classes, and stored for 1 and 2 years at three different temperatures, were used. The consistency of the cooked rices was also determined by the Haake consistometer. The sieve test gave a very good indication of the stickiness of cooked rice. The adhesion test also gave a fair indication, but the correlation was less sharp and the test needs improvement. Consistency of cooked rice was negatively correlated with its stickiness. The water-insoluble amylose content of rice seemed to be importantly related to its stickiness and consistency after cooking.     

Sodium Diffusion and Leaching of Simulated Nuclear Waste Glass

Oxides such as CaO, ZnO, Fe₂0O₃, and Zr0O₂ were substituted for Si0O₂ into a 14 Na₂0-10 B₂0O₃-76 Si0O₂ (wt%) glass in proportion to their weight percent in PNL-7668 simulated nuclear waste glass. No correlation was found between the Na diffusion coefficient (D_Na) in the bulk glass and sodium leaching in water for any of the iron-containing borosilicate glasses. Effective diffusion coefficients calculated from the sodium leach rates in deionized water were 500 to 2000 times larger than D_Na. The experimental leaching data agreed with a diffusion-convection model where the convective term was a measured "phase-boundary" velocity moving into the glass.