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Monitoring Land-Use/Land-Cover Changes at a Provincial Large Scale Using an Object-Oriented Technique and Medium-Resolution Remote-Sensing Images
摘要： An object-based image analysis (OBIA) technique is replacing traditional pixel-based methods and setting a new standard for monitoring land-use/land-cover changes (LUCC). To date, however, studies have focused mainly on small-scale exploratory experiments and high-resolution remote-sensing images. Therefore, this study used OBIA techniques and medium-resolution Chinese HJ-CCD images to monitor LUCC at the provincial scale. The results showed that while woodland was mainly distributed in the west, south, and east mountain areas of Hunan Province, the west had the largest area and most continuous distribution. Wetland was distributed mainly in the northern plain area, and cultivated land was distributed mainly in the central and northern plains and mountain valleys. The largest impervious surface was the Changzhutan urban agglomerate in the northeast plain area. The spatial distribution of land cover in Hunan Province was closely related to topography, government policy, and economic development. For the period 2000–2010, the areas of cultivated land transformed into woodland, grassland, and wetland were 183.87 km2, 5.57 km2, and 70.02 km2, respectively, indicating that the government-promoted ecologically engineered construction was yielding some results. The rapid economic growth and urbanization, high resource development intensity, and other natural factors offset the gains made in ecologically engineered construction and in increasing forest and wetland areas, respectively, by 229.82 km2 and 132.12 km2 from 2000 to 2010 in Hunan Province. The results also showed large spatial differences in change amplitude (LUCCA), change speed (LUCCS), and transformation processes in Hunan Province. The Changzhutan urban agglomerate and the surrounding prefectures had the largest LUCCA and LUCCS, where the dominant land cover accounted for the conversion of some 189.76 km2 of cultivated land, 129.30 km2 of woodland, and 6.12 km2 of wetland into impervious surfaces in 2000–2010. This conversion was attributed to accelerated urbanization and rapid economic growth in this region.
关键词： change monitoring,object-based image analysis,provincial scale,HJ-CCD images
更新于2025-09-23 15:23:52
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Battery-assisted low-cost hydrogen production from solar energy: Rational target setting for future technology systems
摘要： The massive implementation of renewable energy requires sophisticated assessments considering the combination of feasible technology options. In this study, a techno-economic analysis was conducted for hydrogen production from photovoltaic power generation (PV) utilizing a battery-assisted electrolyzer. The installed capacity of each component technology was optimized for the wide range of unit costs of electricity from the PV, battery, and proton-exchange membrane electrolyzer. Leveling of PV output by battery, the necessary capacity of electrolyzer is suppressed and the operating ratio of electrolyzer increases. The battery-assist will result in a lower hydrogen production cost when the benefit associated with the smaller capacity and higher operation ratio of the electrolyzer exceeds the necessary investment for battery installation. The results from this study indicated the cost of hydrogen as low as 17 to 27 JPY/Nm3 using a combination of technologies and the achievement of ambitious individual cost targets for batteries, PV, and electrolyzers.
关键词： Techno-economic analysis,Technology roadmap,Off-grid production,Proton-exchange membrane electrolyzer
更新于2025-09-23 15:23:52
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On investigations of refractive indices and birefringence of fiber using duplicate and non-duplicate micro-interferograms of double refracting interferometer
摘要： The formula of refractive index of fiber considering the refraction has been reviewed. This formula is used to investigate the effect of refraction on the accuracy of refractive index calculations with different simulated micro-interferograms of duplicate interference fringes with different fringe shifts order. Also a more accurate formula to calculate the birefringence from the non-duplicate interference fringes has been derived and tested to calculate the birefringence of simulated and experiment micro-interferogram. The presented micro-interferograms were automatically analyzed and the contour lines of the bright fringes were determined using Fourier transform technique. A prepared software program takes the contour line of the fringes and automatically calculate the refractive index, the radius, and the birefringence of fiber. A good result was obtained in case of using immersion liquid matches between the parallel and perpendicular refractive indices of fiber.
关键词： image analysis,refractive index profile,interferometry,birefringence of fiber
更新于2025-09-23 15:23:52
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Texture features analysis on micro-structure of paste backfill based on image analysis technology; 基于图像识别技术的膏体微观结构纹理特征分析;
摘要： The strength of cement-based materials, such as mortar, concrete and cement paste backfill (CPB), depends on its microstructures (e.g. pore structure and arrangement of particles and skeleton). Numerous studies on the relationship between strength and pore structure (e.g., pore size and its distribution) were performed, but the micro-morphology characteristics have been rarely concerned. Texture describing the surface properties of the sample is a global feature, which is an effective way to quantify the micro-morphological properties. In statistical analysis, GLCM features and Tamura texture are the most representative methods for characterizing the texture features. The mechanical strength and section image of the backfill sample prepared from three different solid concentrations of paste were obtained by uniaxial compressive strength test and scanning electron microscope, respectively. The texture features of different SEM images were calculated based on image analysis technology, and then the correlation between these parameters and the strength was analyzed. It was proved that the method is effective in the quantitative analysis on the micro-morphology characteristics of CPB. There is a significant correlation between the texture features and the unconfined compressive strength, and the prediction of strength is feasible using texture parameters of the CPB microstructure.
关键词： cement paste backfill,unconfined compressive strength,Tamura texture,microstructure,quantitative analysis,texture feature,GLCM feature
更新于2025-09-23 15:23:52
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Detection of Faint Asteroids Based on Image Shifting and Stacking Method
摘要： In order to improve the ability to find the faint and small celestial bodies in the solar system, a method of shifting and stacking images which improves the detection efficiency of faint moving objects is applied to process the sequential optical images. This method determines the existence of moving objects by using the method of false position to pre-estimate the apparent velocities of moving objects, then determines iteratively the accurate positions of moving objects based on the SNR (Signal-to-Noise Ratio) and elongation of stellar image. Using the sequential images of the China Near Earth Object Survey Telescope (CNEOST), we carry out an experiment and succeed in detecting asteroids fainter than 21 magnitude which are invisible on a single image. Thus, the feasibility of this method is verified.
关键词： techniques: image processing,astrometry,instrumentation,methods: data analysis,telescope,methods: observational
更新于2025-09-23 15:23:52
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Non-destructive assessment of the oxidative stability of intact macadamia nuts during the drying process by near-infrared spectroscopy
摘要： We have developed a rapid non-destructive method to assess the oxidative stability of intact macadamia nuts using near-infrared spectroscopy (NIRS). Intact macadamia nuts of the cultivars HAES 344 'Kau', HAES 660 'Keaau', IAC 4-12 B, and IAC Campinas B were harvested and immediately oven-dried for 4 days at 30 °C, 2 days at 40 °C, and 1 day at 60 °C to achieve 1.5% kernel moisture content. At each drying step nuts were withdrawn and their moisture content, peroxide value (PV), and acidity index (AI) determined. The best partial least square model for PV prediction was obtained using the Savitzky-Golay (SG) second derivative resulting in a standard error of prediction (SEP) of 0.55 meq·kg?1 and a coefficient of determination (R2 C) of 0.57. The best AI prediction-model result was obtained using the SG second derivative (SEP = 0.14%, R2 C = 0.29). Based on the maximum quality limits of 3 meq·kg?1 for PV and 0.5% for AI, the SEP values represented 18% and 28%, respectively. Therefore, the prediction method can be considered useful since the errors are lower than the quality limits. Thus, NIRS can be used to assess the oxidative stability of intact macadamia kernels.
关键词： principal component analysis,peroxide value,Macadamia integrifolia Maiden & Betche,acidity index
更新于2025-09-23 15:23:52
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Assessment of different combinations of meteorological parameters for predicting daily global solar radiation using artificial neural networks
摘要： In this study, for determining the best-input scenarios of the used parameters in predicting the Daily Global Solar Radiation (DGSR), a new approach based on Artificial Neural Networks (ANNs) was presented. The proposed approach is based on comparisons between all possible input combinations for determining the best scenarios that can give perfect correlations and approximations with DGSR. Recorded data from 35 stations belonging to different climatic zones (27 in Morocco and 8 in neighboring countries) were reported for training and testing the obtained results. The used input parameters include geographical coordinates, sun declination, day length, day number, clearness index (KI), Top Of Atmosphere (TOA), average ambient temperature (Ta), maximum temperature (Tmax), minimum temperature (Tmin), difference temperature (ΔT), temperature ratio (TR), relative humidity (Rh) and wind speed (Ws). The results revealed 128 best-input scenarios, where the first relevant input combination was found for KI, Ta, ΔT, TR and TOA. This result indicated that the best-input scenario for predicting DGSR is based only on three climatological parameters: KI, function of Ta f(Ta) and TOA. In addition, based on these found best-input scenarios and on the least square regression (LSR) technique, 128 new linear relationships between DGSR and the found best-input combinations were developed. The statistical analysis expressed through statistical criteria indicated perfect correlations and approximations between the predicted and measured values of DGSR.
关键词： Best scenarios,ANNs,Least square regression,Statistical analysis,Solar radiation modelling,Forecasting
更新于2025-09-23 15:23:52
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PV shading fault detection and classification based on I-V curve using principal component analysis: Application to isolated PV system
摘要： Health monitoring and diagnosis of photovoltaic (PV) systems is becoming crucial to maximise the power production, increase the reliability and life service of PV power plants. Operating under faulty conditions, in particular under shading, PV plants have remarkable shape of current-voltage (I-V) characteristics in comparison to reference condition (healthy operation). Based on real electrical measurements (I-V), the present work aims to provide a very simple, robust and low cost Fault Detection and Classi?cation (FDC) method for PV shading faults. At ?rst, we extract the features for di?erent experimental tests under healthy and shading conditions to build the database. The features are then analysed using Principal Component Analysis (PCA). The accuracy of the data classi?cation into the PCA space is evaluated using the confusion matrix as a metric of class separability. The results using experimental data of a 250 Wp PV module are very promising with a successful classi?cation rate higher than 97% with four di?erent con?gurations. The method is also cost e?ective as it uses only electrical measurements that are already available. No additional sensors are required.
关键词： Fault classi?cation,Principal component analysis,Fault detection,I-V curves,PV shading faults
更新于2025-09-23 15:23:52
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SNR analysis and estimation for efficient phase noise mitigation in millimetre-wave SC-FDE systems
摘要： This study demonstrates a signal-to-noise ratio (SNR) analysis and estimation algorithm for efficient phase noise mitigation that can be practically applied to single-carrier frequency-domain-equalisation (SC-FDE) systems that operate in millimetre-wave bands. First, the effect of phase noise in SC-FDE systems is investigated on each of the packet reception processes, namely, channel estimation, SNR estimation, and data-field reception. According to the analysis, an SNR estimation algorithm is proposed. The performance of minimum-mean-square-error equalisation and conventional phase noise mitigation algorithm can be enhanced using the proposed SNR estimation. The effectiveness of the proposed analysis and SNR estimation algorithm is verified through the link-level simulation. Compared with the conventional SNR estimation and the iterative phase noise mitigation algorithms, the proposed algorithm provides a lower packet-error rate without any iterative decoding process.
关键词： SNR analysis,phase noise mitigation,millimetre-wave,channel estimation,SC-FDE systems,packet-error rate
更新于2025-09-23 15:23:52
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Definition of design guidelines, construction, and performance of an ultra-stable scanning tunneling microscope for spectroscopic imaging
摘要： Spectroscopic-imaging scanning tunneling microscopy is a powerful technique to study quantum materials, with the ability to provide information about the local electronic structure with subatomic resolution. However, as most spectroscopic measurements are conducted without feedback to the tip, it is extremely sensitive to vibrations coming from the environment. This requires the use of laboratories with low-vibration facilities combined with a very rigid microscope construction. In this article, we report on the design and fabrication of an ultra-stable scanning tunneling microscope (STM) for spectroscopic-imaging measurements that operates in ultra-high vacuum and at low temperatures (4 K). We start from existing designs with sapphire as the main material and improve the stiffness further by performing finite element analysis calculations for the main components of the microscope to guide design choices on the geometry of the parts. With this strategy, we construct a STM head with measured lowest resonant frequencies above f0 = 13 kHz for the coarse approach mechanism, a value three times higher than what has been previously reported and in good agreement with the calculations. This allows us to achieve an average vibration level of ～6 fm/√Hz, without a dedicated low-vibration lab. We demonstrate the microscope’s performance with topographic and spectroscopic measurements on the correlated metal Sr2RhO4, showing the quasiparticle interference pattern in real and reciprocal space with high signal-to-noise ratio.
关键词： ultra-high vacuum,low temperature,spectroscopic imaging,finite element analysis,ultra-stable,scanning tunneling microscopy
更新于2025-09-23 15:23:52