Detecting changes in the land-use and vegetation conditions by using remote-sensing techniques is a common approach nowadays to assessing human-induced impacts in a specific area. For this purpose, a series of vegetation indices and change detection algorithms such as the normalized difference vegetation index (NDVI), Iterative Self-Organizing Data Analysis Technique (ISODATA), and k-means have been efficiently developed and used in many studies worldwide. However, identifying the driving forces for the estimated changes in land use and vegetation has always been a difficult and challenging task. In this study, Landsat and Système Pour l'Observation de la Terre (SPOT) images have been used to estimate the NDVI and land-use changes at the Plastira artificial lake catchment in the period 1984–2009. The recorded vegetation changes were correlated with a series of environmental and human-related parameters such as precipitation, temperature, specific land uses, and topography to identify the dominant factors of the aforementioned changes. This was done using both linear and geographically weighted regression methods. The results indicate that the precipitation and temperature fluctuations are strongly correlated with the vegetation conditions, whereas, as far as the topographic parameters are concerned, the aspect and slope affect mostly the particular vegetation index (the NDVI) of the study area. 相似文献
Organizations and businesses, including financial institutions and healthcare providers, are increasingly collecting and disseminating information about individuals in the form of transactions. A transaction associates an individual with a set of items, each representing a potentially confidential activity, such as the purchase of a stock or the diagnosis of a disease. Thus, transaction data need to be shared in a way that preserves individuals'' privacy, while remaining useful in intended tasks. While algorithms for anonymizing transaction data have been developed, the issue of how to achieve a "desired" balance between disclosure risk and data utility has not been investigated. In this paper, we assess the balance offered by popular algorithms using the R-U confidentiality map. Our analysis and
experiments shed light on how the joint impact on disclosure risk and data utility can be examined, which allows the production of high-quality anonymization solutions. 相似文献
A new hybrid adaptive algorithm based on particle swarm optimization (PSO) is designed, developed and applied to the high school timetabling problem. The proposed PSO algorithm is used to create feasible and efficient timetables for high schools in Greece. Experiments with real-world data coming from different high schools have been conducted to show the efficiency of the proposed PSO algorithm. As well as that, the algorithm has been compared with four other effective techniques found in the literature to demonstrate its efficiency and superior performance. In order to have a fair comparison with these algorithms, we decided to use the exact same input instances used by these algorithms. The proposed PSO algorithm outperforms, in most cases, other existing attempts to solve the same problem as shown by experimental results. 相似文献
Eight types of A356 Al–fly ash composites were produced by pressure infiltration of high-Ca lignite fly ash. This type of
ash was used for the first time in Al-composites synthesis, and particularly by liquid metal infiltration techniques. After
examining mineralogy and chemistry, specific, narrow ash size fractions were used for the synthesis of composites, and properties
linked to microstructure and wear strength of the materials. The effect of using ground ash particles on the microstructure
and tribological performance of the composites was also investigated. It was concluded that using fine, high-Ca ash particles
can improve the properties of composites, and that using ash particles in a ground form can better facilitate the production
process of MMCs. 相似文献
In this paper, the architecture of a low-complexity Direct Sequence Ultra-Wideband (DS-UWB) receiver subsystem which incorporates a Channel Estimator (CE) and a novel hybrid Partial/Selective (HPS) maximal ratio combining (MRC) RAKE receiver is presented. Three different design techniques followed by FPGA implementation are investigated and compared and system performance results are provided. The proposed architectures combine the benefits of both partial and selective RAKE receiver algorithms and the obtained results demonstrate the trade-off between energy capture, performance and receiver complexity. All design approaches focus on a highly parallel, modular and optimized for high performance system which is necessary for demanding and low-cost applications of UWB communications. 相似文献
The expression of glutamate receptor/subunit mRNAs was examined 3 weeks after discontinuing 1 week of daily injections of saline or cocaine. The level of mRNA for GluR1-4, NMDAR1, and mGluR5 receptors was measured with in situ hybridization and RT-PCR. In nucleus accumbens, acute cocaine treatment significantly reduced the mRNA level for GluR3, GluR4, and NMDAR1 subunits, whereas repeated cocaine reduced the level for GluR3 mRNA. Acute cocaine treatment also reduced the NMDAR1 mRNA level in dorsolateral striatum and ventral tegmental area. In prefrontal cortex, repeated cocaine treatment significantly increased the level of GluR2 mRNA. The GluR2 mRNA level was not changed by acute or repeated cocaine in any other brain regions examined. Repeated cocaine treatment also significantly increased mGluR5 mRNA levels in nucleus accumbens shell and dorsolateral striatum. Functional properties of the ionotropic glutamate receptors are determined by subunit composition. In addition, metabotropic glutamate receptors can modulate synaptic transmission and the response to stimulation of ionotropic receptors. Thus, the observed changes in levels of AMPA and NMDA receptor subunits and the mGluR5 metabotropic receptor may alter excitatory neurotransmission in the mesocorticolimbic dopamine system, which could play a significant role in the enduring biochemical and behavioral effects of cocaine. 相似文献
Optimal solutions in environmental catalysis require a well-coordinated development of catalysts and of process design. This contribution is devoted to energy integrated design concepts for fuel reforming and for automotive exhaust purification. The examples presented demonstrate the importance of an innovative process design for optimal utilization of existing catalysts and show the potential of future developments.
New concepts for steam reforming through the efficient coupling of the endothermic reforming reaction with an exothermic combustion reaction are discussed in the first part. These concepts have been implemented for methanol steam reforming in a counter-current reactor with distributed side feed of burner gas and for methane steam reforming in a modular reactor with a co-current reaction section for the endothermic and the combustion reaction and attached counter-current heat exchangers. Both applications employ the so-called folded sheet reactor design, which ensures an excellent heat transfer between the reforming and combustion channels and efficient heat recovery.
A similar design solution is introduced for the apparently different case of automotive exhaust purification. The proposed concept aims at decoupling exhaust after-treatment from engine control. Its main component is a counter-current heat exchanger with integrated purification stages for HC-oxidation, NOX storage and reduction and soot filtering. A small catalytic burner at the hot end of the heat exchanger provides both heat and oxidizing or reducing agents on demand. A new soot filter design allows for safe soot filter regeneration. 相似文献