Land Surface Water Index (LSWI) response to rainfall and NDVI using the MODIS Vegetation Index product

For more than 20 years the Normalized Difference Vegetation Index (NDVI) has been widely used to monitor vegetation stress. It takes advantage of the differential reflection of green vegetation in the visible and near-infrared (NIR) portions of the spectrum and provides information on the vegetation condition. The Land Surface Water Index (LSWI) uses the shortwave infrared (SWIR) and the NIR regions of the electromagnetic spectrum. There is strong light absorption by liquid water in the SWIR, and the LSWI is known to be sensitive to the total amount of liquid water in vegetation and its soil background. In this study we investigated the LSWI characteristics relative to conventional NDVI-based drought assessment, particularly in the early crop season. The area chosen for the study was the state of Andhra Pradesh located in the Indian peninsular. The Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Index (VI) product from the Aqua satellite was used in the study. The analysis was carried out for the years 2002 (deficit year) and 2005 (normal year) using the NDVI from the MODIS VI product and deriving the LSWI using the NIR and SWIR reflectance available with the MODIS VI product. The response of LSWI to rainfall, observed in the rate of increase in LSWI in the subsequent fortnights, shows that this index could be used to monitor the increase in soil and vegetation liquid water content, especially during the early part of the season. The relationship between the cumulative rainfall and the current fortnight LSWI is stronger in the low rainfall region (<500 mm), while the one-fortnight lagged LSWI had a stronger relationship in the high rainfall region (>500 mm). The relationship between LSWI and the cumulative rainfall for the entire state was mixed in 2002 and 2005. The strength of the relationship was weak in the high rainfall region. When LSWI was regressed directly with NDVI for three LSWI ranges, it was observed that the NDVI with the one-fortnight lag had a strong relationship with the LSWI in most of the categories.     

提高《编译原理》教学效果的探索

针对《编译原理》这门课程的特点及教学现状,探讨提高《编译原理》教学效果的方法。从课堂教学、实践教学、分层教学等方面分别提出一些建议,用以提高学生的学习兴趣和实践动手能力．达到有效提升教学效果的目的。     

An Image Processing Method for Cardiac Motion Analysis

A new image processing method is developed to process two-dimensional ultrasound B-scan echo images which makes possible the delineation of the displacement of cardiac boundaries for the precise assessment of infarcted/ischemic regions. An economic image processing system is designed for the purpose. An algorithm to compute the direction and amplitude of the displacement vector at any point in the cardiac image, given two frames of the image at two different time instants, is developed. The performance of the algorithm is examined with synthesized images. Displacement amplitudes along the boundaries of the left ventricle are plotted and compared for normal and diseased conditions.     

Field evaluation of UHF radio propagation for an ITS safety system in an urban environment

Roadside-to-vehicle and vehicle-to-vehicle communication systems have been proposed as part of ITS development to help achieve vehicle safety and realize more secure road traffic environments. In this article we first introduce several typical applications and their radio range requirements for vehicle safety communication systems to clarify the technical point of view. Then we show some field experiment results in an urban area in Tokyo to investigate and verify the radio propagation characteristics and the quality of communications by using a wireless radio prototype system. Finally, we conclude that the current prototype system has potential to fulfill the radio range requirements of vehicle safety communications, but there are still lots of issues that need to be addressed.     

Polarisation-independent vertically coupled microring resonatorfilter

A polarisation-independent microring resonator filter is proposed using a birefringent polymer overlay. The thickness of the polymer overlay is optimally designed and the polarisation-independent operation successfully demonstrated     

Characterizing cyclic and static moduli and strength of compacted pavement subgrade soils considering moisture variation

Compacted soils are widely used as the subgrade layer for pavements. Knowledge of the mechanical properties of subgrade soils under cyclic and static loading conditions and their variation under the influence of environmental factors is required for the rational design of pavements based on mechanistic methods. This paper presents an experimental investigation of the cyclic and static moduli and the strength properties of seven different compacted Canadian subgrade soils considering the variation in the post-compaction moisture content. Cyclic triaxial tests were performed to reliably determine the resilient modulus (M_R). Unconfined compression tests, which allow an unloading-reloading loop at 1% strain, were performed to determine the deviator stress (S_u1%) at 1% strain, the reloading elastic modulus (E_1%) at 1% strain and the unconfined compressive strength (q_u) at failure. The physical properties, the chemical and mineralogical compositions, and the soil-water characteristics of these soils were also determined. Relationships were developed to predict the M_R from the S_u1%, E_1%, q_u and soil physical properties for the investigated subgrade soils because the experimental determination of M_R is both expensive and time-consuming. The studies presented in this paper provide useful information and approaches that can be used to promote the implementation of mechanistic pavement design methods using simple techniques.     

磁流变材料在现代加工设备中的应用

磁流变(MR)材料是一种新型的智能材料,是由载液、表面活性剂、可磁化分散粒子等组成的一种流体。在外加磁场的控制下磁流变装置能够产生连续可控的阻尼力,从而对振动系统的振动性能进行实时控制。它的特性及应用都处于研究和探索阶段,但从初步实验成果来看磁流变材料有着广阔的应用前景,尤其是在减振降噪方面。简要介绍了磁流变材料的特性,归纳了磁流变材料在现代加工设备中的应用现状,展望了磁流变材料在现代加工设备中的应用前景。     

Influence of filter media depth and vegetation on Faecal Coliform removal by stormwater biofilters

Biofilters are promising technologies that widely applied in the treatment of urban stormwater. However, the microbial removal capacity performance depends greatly on the design of biofilters. Hence, this laboratory study attempts to investigate the influence of filter media depths (i.e. 150, 250, 350 and 450 mm) and the variation of native plants, that is, Cow Grass (Axonopus compressus) and Pearl Grass (Axonopus compressus, dwarf) in removing stormwater microorganism particularly Faecal Coliform (FC). Findings showed that a minimum media depth of 300 mm was required to achieve >1 log FC removal. The mean removal of FC at 450 mm depth filter exceeded 2 log for both Cow and Pearl grass biofilter columns. Results showed that there was no statistically significant difference in vegetation type on the performance of FC removal, however, Cow grass biofilter column revealed higher FC mean log removal compared to Pearl grass biofilter column.