重力场中铝热剂的燃烧特性研究

研究了重力场作用下有液相生成的铝热剂的燃烧特性。研究了CaO,CaF2等添加剂以及预热温度对铝热剂燃烧温度和燃烧速率的影响。结果表明,在重力作用下有液相生成的铝热剂的燃烧速率为反应产物熔体未反应粉末中的渗透速率。提高预热温度可使燃烧温度升高,燃烧速率增大。     

数字矿山系统框架与关键技术研究

数字矿山是当今采矿科学、信息科学、人工智能、计算机技术和3S技术发展与高度结合的产物,它将深刻改变传统的采矿生产活动和人们的生活方式。分析了数字矿山的内涵和基本特征,对数字矿山的层次结构和系统框架进行了研究,讨论了数字矿山战略实施的关键技术,并对数字矿山的发展前景做了初步的展望。     

Analysis of etched long-period fibre grating and its response to external refractive index

Analytical formulas are presented for the first time to describe the shift in the resonance wavelength of a long-period fibre grating (LPFG) in response to etching of the fibre cladding or a change in the external refractive index. The accuracy of the formulas is confirmed by comparison with numerical simulations and experimental results. It is shown that the resonance wavelengths of an etched LPFG are more sensitive to the external refractive index than those of an unetched grating.     

A general approach for analysis and application of discretemultiwavelet transforms

This paper proposes a general paradigm for the analysis and application of discrete multiwavelet transforms, particularly to image compression. First, we establish the concept of an equivalent scalar (wavelet) filter bank system in which we present an equivalent and sufficient representation of a multiwavelet system of multiplicity r in terms of a set of r equivalent scalar filter banks. This relationship motivates a new measure called the good multifilter properties (GMPs), which define the desirable filter characteristics of the equivalent scalar filters. We then relate the notion of GMPs directly to the matrix filters as necessary eigenvector properties for the refinement masks of a given multiwavelet system. Second, we propose a generalized, efficient, and nonredundant framework for multiwavelet initialization by designing appropriate preanalysis and post-synthesis multirate filtering techniques. Finally, our simulations verified that both orthogonal and biorthogonal multiwavelets that possess GMPs and employ the proposed initialization technique can perform better than the popular scalar wavelets such as Daubechies'D8 wavelet and the D(9/7) wavelet, and some of these multiwavelets achieved this with lower computational complexity     

Design of polarization-insensitive Bragg gratings inzero-birefringence ridge waveguides

Addresss the problem of designing polarization-insensitive Bragg gratings in zero-birefringence ridge waveguides. It is known that the reflection spectrum of a Bragg grating is be polarization-independent if both the phase-matching condition and the coupling coefficient are polarization-independent. While the use of a zero-birefringence waveguide can guarantee a polarization-independent phase-matching condition, it does not in general lead to a polarization-independent coupling coefficient. Our theoretical analysis indicates, however, that a strictly polarization-independent coupling coefficient is not essential for the achievement of a polarization-insensitive Bragg grating. Our detailed calculations on both corrugation and phase gratings in zero-birefringence ridge waveguides reveal some general design principles. Our results should be useful for the design of a wide range of Bragg-grating-based waveguide devices     

High efficiency, wide dynamic range variable gain and poweramplifier MMICs for wideband CDMA handsets

A linearized variable gain amplifier (VGA) and a two-stage power amplifier (PA) MMIC were developed for 1.95-GHz wideband CDMA (W-CDMA) handsets application. A complete PA block with power control ability was obtained by cascading the VGA with the PA. The linearized VGA consists of a predistorter (PD) integrated with a conventional VGA, performing dual function for achieving high linearity power control, as well as reducing output distortion level of the following PA. With the use of predistortion, the P_out and power added efficiency (PAE) of the PA block improved from 27.5 dBm and 39.8% to 28.5 dBm and 44.8%, respectively, measured at -35 dBc adjacent channel leakage power ratio (ACPR). Under power control operation, the control range of the PA block increased from 23.6 dB to 31.2 db, and ACPR reduction of over 10 dB was achieved with the use of linearized VGA     

Alginate‐Based Emulsion Template Containing High Oil Loading Stabilized by Nonionic Surfactants

Oil‐in‐water (O/W) emulsion‐gel systems containing high oil payloads are of increasing interest for food applications because of the reduction in encapsulation cost, consumption frequency or volume of food products. This study shows a facile approach to prepare stable alginate‐based O/W emulsions at high oil loading using a mixture of nonionic surfactants (Tween 80 and Span 20) as a template to form gelled‐emulsions. The synergistic effects of alginate and surfactants on the O/W emulsion properties were evaluated in terms of oil droplet size and emulsion stability. At 2% (w/v) of alginate and 1% (w/v) of surfactants, the size distribution of oil droplets was narrow and monomodal, even at an oil loading of 70% (v/v). The emulsions formed were stable against phase separation. The oil droplet size could be further reduced to below 1 μm using a high‐shear homogenizer. The emulsions formed could be easily molded and gelled into solids of different shapes via ionic gelation. The findings of this study create possible avenues for applications in food industries.     

低聚糖和多酚结合偏最小二乘判别分析鉴别油菜蜜产地

采用气相色谱-串联质谱技术测定油菜蜜中6 种低聚糖成分,高效液相色谱-串联质谱技术测定油菜蜜中18 种酚酸物质,并结合偏最小二乘判别分析（partial least square-discrimination analysis,PLS-DA）对来自湖北钟祥市、江苏盐城市、青海刚察县3 个具有显著地理、气候、环境差异的51 个油菜蜜样本进行产地鉴别。方差分析结果显示：3 个产地油菜蜜中松二糖含量具有显著性差异,且青海刚察油菜蜜低聚糖含量相对偏高;油菜蜜的18 种多酚类物质中大多数具有显著的地理差异性且湖北钟祥的油菜蜜中多酚含量相对偏高。多元统计分析结果显示多酚具有显著的地理特征性。油菜蜜中低聚糖和多酚的含量结合PLS-DA产地鉴别的预测精度可达到97%。     

综合回收有色金属物料中伴生钴的研究概况

本文比较全面地阐述了目前国内外从含钴矿石和含钴物料（含钴废水,含钴浸出液等）中回收钴的现状以及所涉及的选矿,湿法冶金,萃取和微生物技术等各种富集和分离方法,同时还就理论和工艺中存在的问题提出了看法,以期对同行科技工作者有所裨益。     

Unravelling charge carrier dynamics in protonated g-C<Subscript>3</Subscript>N<Subscript>4</Subscript> interfaced with carbon nanodots as co-catalysts toward enhanced photocatalytic CO<Subscript>2</Subscript> reduction: A combined experimental and first-principles DFT study

In this work,we demonstrated the successful construction of metal-free zerodimensional/two-dimensional carbon nanodot (CND)-hybridized protonated g-C3N4 (pCN) (CND/pCN) heterojunction photocatalysts by means of electrostatic attraction.We experimentally found that CNDs with an average diameter of 4.4 nm were uniformly distributed on the surface of pCN using electron microscopy analysis.The CND/pCN-3 sample with a CND content of 3 wt.％ showed the highest catalytic activity in the CO2 photoreduction process under visible and simulated solar light.Thisprocess results in the evolution of CH4 and CO.The total amounts of CH4 and CO generated by the CND/pCN-3 photocatalyst after 10 h of visible-light activity were found to be 29.23 and 58.82 μmol·gcatalyst-1,respectively.These values were 3.6 and 2.28 times higher,respectively,than the amounts generated when using pCN alone.The corresponding apparent quantum efficiency (AQE) was calculated to be 0.076％.Furthermore,the CND/pCN-3 sample demonstrated high stability and durability after four consecutive photoreaction cycles,with no significant decrease in the catalytic activity.The significant improvement in the photoactivity using CND/pCN-3 was attributed to the synergistic interaction between pCN and CNDs.This synergy allows the effective migration of photoexcited electrons from pCN to CNDs via wellcontacted heterojunction interfaces,which retards the charge recombination.This was confirmed by photoelectrochemical measurements,and steady-state and time-resolved photoluminescence analyses.The first-principles density functional theory (DFT) calculations were consistent with our experimental results,and showed that the work function of CNDs (5.56 eV) was larger than that of pCN (4.66 eV).This suggests that the efficient shuttling of electrons from the conduction band of pCN to CNDs hampers the recombination of electron-hole pairs.This significantly increased the probability of free charge carriers reducing CO2 to CH4 and CO.Overall,this study underlines the importance of understanding the charge carrier dynamics of the CND/pCN hybrid nanocomposites,in order to enhance solar energy conversion.