The study of lakes dynamic change based on RS and GIS –Take DaLiNuoEr Lake as an example

AbstractIn the study, TM images in eight periods was the data source, adopted RS and GIS technology, threshold value method, deference value and other methods,Statistics the water area of Dalinor from 1995 to 2009 in past 15 years. By establishing lake's Digital Elevation Model (DEM), it was analyzed dynamic change of Dalinor lakes volume in nearly 15 years. In this 15years, Dalinor lake's area narrowed from 246.7km2 in 1995 to 218 km2 in 2009, Lake area reduced 28.7km2, The average decrease speed was 2.05 km2 / a. The total volume narrowed from 4359821563.03 m3 in 1995 to 3889917491.37 m3 in 2009, the total volume reduced 469904071.66 m3, the average decrease speed was 33564576.55 m3 / a. Lake area and volume declined sharply

EPITAXIAL GROWTH OF LANTHANIDE-DOPED UPCONVERSION CRYSTALS

Ph.DDOCTOR OF PHILOSOPH

Notes on the Hermitian Positive Definite Solutions of a Matrix Equation

The nonlinear matrix equation, X-∑i=1mAi*XδiAi=Q, with -1≤δi<0 is investigated. A fixed point theorem in partially ordered sets is proved. And then, by means of this fixed point theorem, the existence of a unique Hermitian positive definite solution for the matrix equation is derived. Some properties of the unique Hermitian positive definite solution are obtained. A residual bound of an approximate solution to the equation is evaluated. The theoretical results are illustrated by numerical examples

Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films

In this work, we present a detailed optical investigation of the effects of the environment on the photoluminescence (PL) spectra and the relaxation dynamics of pristine and aged CsPbBr 3 nanocrystal (NC) thin films. We demonstrate that, contrary to previous results on similar NCs, the PL intensity of pristine NCs is higher when the sample is in wet air than in vacuum, due to the passivation of defects reducing the free exciton trapping and the bound excitons non-radiative relaxation. The aged NCs show a PL intensity increase in wet air nine times stronger than the pristine ones, due to an interplay between static and dynamic effects, increasing the number of emitting NCs and reducing the non-radiative recombination rate of free excitons. These results improve the understanding of the possible interactions between perovskite NCs and the environment, which could be relevant for the development of optical gas sensors exploiting perovskite NCs

Application of high-resolution remote sensing technology for the iron ore deposits of the West Kunlun Mountains in China

This study focuses on the iron ore of Taxkorgan and Heiqia in the West Kunlun mountains as a case study, for the application of WorldView−2 and IKONOS remote sensing images as major data sources in the fabrication of a standard image map and in the adoption of image enhancement methods to extract information on the ore-controlling factors and mineralization, to interpret remote sensing for the mineral resources in these areas. ASTER, WorldView−2, and IKONOS data were applied for the extraction of alteration anomaly information. With an appropriate amount of field sampling and verification tests, this was used to establish a remote sensing geology prospecting model, that would provide the basis for future remote sensing of metallogenic belts in  West Kunlun in the hope of discovering similar minerals. Survey results showed four additional iron ore mineralization belts could be delineated in the Taxkorgan area. A comparative analysis conducted for part of the field confirmation and the known mineral deposits indicated good reliability. In Heiqia, a siderite-haematite mineralization zone was observed with copperlead- zinc formation, 60-km in length and 200–500 m wide, which includes several mineralized bodies. The ore bodies, appear as stratoid, lenticular, or podiform morphologies and were located in the transition site from clastic to carbonate rocks of the D segment in the Wenquangou Group. The ore bodies generally occur within 40°–50° strike and 68°–81° dip, in accordance to the strata. The length of the single body varies from several hundred metres to more than 9500 m. Its exposed thickness on the surface ranges from 2–50 m, and the general thickness was approximately 15 m. The surface ore minerals were mainly haematite and limonite, with a small amount of siderite. Therefore, high-resolution remote sensing technology is suitable for iron ore geological and mineral remote sensing surveying. It is advantageous in both high-ground resolution of optical characteristics and a certain spectral recognition capability, and is effective not only for information extraction from a large area, but also for recognition of local mineralization outcrops. Therefore, high-resolution remote sensing technology is valuable for popularization.

New concept and design of electronically controlled cylinder lubrication system for large two-stroke marine diesel engines

Lubrication of cylinders between liners and rings is one of the crucial factors that affects the efficient operation of diesel engines. Marine diesel engines usually use inferior heavy fuel oil with high sulphur content, and the acidic substances formed by fuel combustion need alkaline cylinder oil to neutralize. For the operational cost to a marine engine, besides fuel oil, cylinder oil also takes a big share. This article first analyses the advantages and disadvantages of existing cylinder lubrication systems with regard to oil injection control. Second, the control parameters and variables such as the oil injection pressure, timing, oil feed rate and reliability are analysed, and the corresponding control schemes formulated. Third, the control strategies are developed in detail. Finally, verification tests are carried out on an actual engine, with the results showing that the control strategies developed in this article provide a stable, cost-effective, creative and excellent solution for cylinder lubrication with reduced cylinder wear. A thin and uniform oil film distribution is retained on the liner surface, with savings in cylinder oil consumption, lower particulate matter emission levels and improved cylinder liner and piston rings running conditions. The experimental results show that the oil consumption could be reduced by up to 5

Design and experimental development of a new electronically controlled cylinder lubrication system for the large two-stroke crosshead diesel engines

Accurate, stable and reliable lubrication for the cylinders is very important to ensure the trouble-free operation of the marine diesel engines. A new electronically controlled cylinder lubrication system has been developed to remedy the defects of the conventional mechanical lubrication system. This new system’s design method, composition and implementation are described. The sensitivity tests are conducted on the test bench and the verification tests are also fulfilled on operating vessels. The main performance data are as follows: oil injection pressure about 3.0 MPa, oil injection timing precision 0.1 ms, oil injection duration 15 °CA or less. The oil injection concentrates onto the piston rings pack to ensure the good lubrication and neutralization, and the oil injection frequency is regulated according to engine load, the sulphur content in fuel, total base number of cylinder oil, cylinder liner running-in condition and so on. This results in the cylinder oil consumption rate falling approximately 25% compared with that of the conventional mechanical lubrication system. As a retrofit on vessels in service, the lubrication system has been fitted more than 120 main engines and has a payback period of less than 2 years