Fast and nondestructive detection of early decay caused by fungal infection in citrus fruit was a challenging task for the citrus industry during the postharvest fruit processing. In general, workers relied on the ultraviolet induction fluorescence technique to detect and remove the decayed citrus fruits in fruit packing houses. However, this operation was harmful for human health, and was also very inefficient. In this study, navel oranges were used as research object. A novel method combining with hyperspectral imaging technology in the wavelength region between 400 and 1100 nm wavelength was proposed to solve this problem. First, normalization approaches were applied to decrease the variation of spectral reflectance intensity due to natural curvature of navel orange surface. Then, the spectral data of regions of interest (ROIs) from normal and decayed tissues was analyzed by principal component analysis (PCA) for investigating the performance of visible and near infrared (Vis-NIR) hyperspectral data to discriminate these two kinds of tissues. Next, six characteristic wavelength images were obtained by analyzing the loadings of the first principal component (PC1). And, a multispectral image was established by using the corrected six characteristic wavelength images. On basis of the multispectral image, pseudo-color image processing with intensity slicing was utilized to produce a two-dimensional color image with clear contrast between decayed and normal tissues. Finally, an image segmentation algorithm by combining the pseudo-color processing method and a global threshold method was proposed for fast identification of decayed navel oranges. For 240 independent samples, the success rates were 100 and 97.5% for decayed navel oranges infected by Penicillium digitatum and normal navel oranges, respectively. In particular, the proposed algorithm was also applied to detect the decayed navel oranges infected by Penicillium italicum (samples not used for the development of algorithm) and obtained a 91.7% identification accuracy, indicating a well generalization ability and actual application value of the proposed algorithm.
A novel localization scheme called laser beam scan localization by combining grid and light (laser) with mobile localization policy for wireless sensor networks is designed. The scheme utilizes a moving location assistant (LA) with a laser beam, through which the deployed area is scanned. The LA sends identities to unknown nodes to obtain the locations of sensor nodes. High localization accuracy can be achieved without the aid of expensive hardware on the sensor nodes, as required by other localization systems. The scheme yields significant benefits compared with other localization methods.
The design and development of the distribution automation terminal based on the modular configuration design is mainly to design the distribution automation terminal hardware according to the different functional requirements as independent hardware modules. The module can be any combination of rail installation, Module installation is no longer due to the traditional chassis structure of the distribution automation terminal due to the size of the chassis and the limited number of slots resulting in limited expansion, so the module type and quantity can be configured according to project requirements; The modules communicate with each other through a full-duplex high-speed bus based on the fast preemption mechanism of channel collision detection and the modules are plug-and-play. This paper mainly researches and expatiate the distribution automation terminal based on the modular configuration design from the aspects of hardware module classification and structure design, high-speed bus interface and communication mechanism design, module adaptive access design and so on, mainly including high-speed bus control technology , High-speed bus resource preemption based on collision detection, plug-and-play technology based on adaptive access, and other technical contents.
Lake Qarhan is the largest salt lake and potassium salt resource mining base in china. Understanding the origin of brines and the contribution of modern water circulation is extremely important to the sustainable development of the salt lake. Comprehensive tools including isotope, hydrochemistry and numerical simulation had been performed. Results suggest that brine groundwater in the salt lake area is the result of ancient brines migrated from the western Qaidam Basin due to the uplift of the western basin in the geological past. Shallow phreatic aquifers in the salt lake area are also recharged by the modern surface water in the flood period. The contribution of modern groundwater circulation to the salt lake area is very limited with only 3% of the total quantity of groundwater discharge for the watershed.
Phreatic groundwater plays a significant role in the water supply for human communities, especially in water scarce regions. This research was conducted to investigate the hydrochemistry and contamination of phreatic groundwater and their constraints on drinking water supply in a semiarid region of the North China Plain. A total of 49 phreatic groundwaters were collected for the hydrochemical analysis. The results suggested the phreatic groundwater had a slightly alkaline nature. Although the groundwater had a large variation of salinity with the TDS of 172–1,875 mg/l, most groundwater was moderately-hard fresh and of HCO 3 -Ca type. Contaminants of NO 3 − , NO 2 − , NH 4 + , Fe, F − , Zn, Mn were detected, but only NO 3 − , NO 2 − , NH 4 + , and Fe were found exceeding the drinking water desirable limits at some sites. The nitrogen contaminants were from anthropogenic inputs (urban sewage effluents and agricultural fertilizers) and mainly distributed in the central study area. The anthropogenic inputs of nitrogen contaminants also elevated groundwater salinity. Among the exceeding contaminants, only NO 3 − would pose a potential health risk to water consumers. The existing health risks by NO 3 − ranged from medium risk (HQ of 1–4) to high risk (hazard quotient > 4) for all populations, and most risks were categorized into the medium risk rank. Groundwater F − was also found with health risk at some sporadic sites although it did not exceed, only approached, the desirable limit. Its health risk was only to infants and categorized into the medium risk with the maximum HQ of 1.55. Most phreatic groundwater (83.67%) in the study area had relatively good quality and was suitable for domestic usage with the EWQI value below 150. Others belonged to the poor (EWQI of 150–200) and extremely poor (EWQI > 200) quality categories, and mainly distributed in the urban Gaocheng. Thus, it is recommended to pay attentions to the anthropogenic contaminants inputs into phreatic aquifers in human activities areas.
Lakes are key factors in maintaining ecosystems in semi-arid regions. However, due to data shortage, most studies used remote-sensing data and water-balance models to analyze lake variations in semi-arid ungauged closed watersheds, resulting in the oversimplified assessment of lake variations and their associated hydrologic processes. This study aimed to enhance the understanding of the mechanisms behind the water supplement and consumption of lakes and reveal the influences of hydrological processes on lake variations in such watersheds. Physically based and lake-oriented hydrologic modeling, remote-sensing technology, and results from previous studies were comprehensively integrated to achieve the research objective. The Hongjiannao (HJN) watershed in Northwest China was selected as the study area of this research. The calibration and validation results demonstrated that remote-sensing data and results from previous studies indeed guaranteed the accuracy of the lake-oriented model. Further hydrologic and statistical analyses revealed the linkage between lake variations and their associated hydrologic processes, and the mechanisms behind the linkage. Specifically, rainfall and snowmelt were found to be the most stable sources of HJN Lake, particularly in dry years. Due to the differences in recession rates, groundwater inflow was more stable than upstream inflow and inflow from the contributing area of HJN Lake. The correlations between hydrologic processes and the storage variation of HJN Lake varied significantly at daily and monthly time scales, which can be explained by the generation mechanisms of these processes. This study provided valuable guidance for water resources management and ecosystem protection in the HJN watershed and can be further applied for hydrologic simulations in other similar watersheds.
The Kunlun Mountains on Tibetan Plateau The Tibetan Plateau, well known as Asian Water Tower, holds immense potential for the formation of glacial mineral water. The present research focuses on the hydrochemical and isotopic signatures and formation pattern of natural glacial mineral water in the alpine region on Tibetan Plateau. The investigated mineral groundwater has outstanding water quality and slightly alkaline nature. It is with fresh hydrochemical facies of HCO3-Na·Ca type with total dissolved solids (TDS) in the range of 384–964 mg/L, and featured by notably rich strontium with the concentrations of 0.67–0.81 mg/L, far exceeding the recommended mineral water minimum threshold of 0.20 mg/L. The mineral groundwater is originated from the glacier meltwater of mountainous area with elevation over 4500 m. It subsequently infiltrates into the bedrock and move within the groundwater system with a residence time of approximately 52 years. Its hydrochemical constituents are naturally governed by water-rock interactions of silicates dissolution, cation exchange, and celestite and strontianite dissolution. A conceptual model is proposed to outline the formation pattern of glacial mineral water in alpine region on Tibetan Plateau. Findings of this study can fill the study gap regarding glacial mineral water on Tibetan Plateau, and further contribute to the future study and development of natural glacial mineral water in alpine regions worldwide.
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