Although the exploitation of mineral areas brings wealth to society, it inevitably leads to the degradation of the surrounding natural environment. To understand and assess the influences of mining activities on the geological and ecological environment, land cover classification in open-pit mine areas (LCCMA) is of great significance. This research proposes an intelligent classification framework for LCCMA based on an object-oriented method and multitask learning (MTL), named the MTL Classification Framework (MTLCF). With the help of MTL, each land cover type in open-pit mine areas obtains its exclusive and receivable object-oriented feature sets using the model-agnostic method. After that, the feature sets are fused with the original images. EfficientNet, a spatial pyramid pooling module, and a global attention upsample module are assembled as the segmentation models with the structure of the encoder and decoder to classify intelligently each land cover type in open-pit mine areas. Finally, the models were trained, and ablation experiments were performed. The experimental results show that our proposed framework -MTLCF was effective for classification in LCCMA, and the overall accuracy and the mean of F1 score for the MTLCF in LCCMA were 85.6% and 86.06%, respectively.
During the production and processing of the cavity surface of a semiconductor laser, micro-defects such as scratches, cracks and grooves will inevitably be caused to the cavity surface. The existence of micro-defects on the cavity surface will affect the distribution of the laser inside the cavity surface, causing the cavity surface temperature to rise sharply. When the temperature reaches the melting point of the cavity surface material, it will cause thermal fusion damage to the cavity surface. When the temperature reaches the vaporization point, microdefects on the surface of the cavity will cause further damage and expansion.In the summary and analysis of the interaction mechanism between laser and optical materials, the temperature distribution and damage expansion model of GaAs cavity surface were established based on the theory of heat conduction and deformation geometry.By comparing and analyzing the damage expansion induced by tapered microdefects with different depths and base radius, it is found that the depth of damage expansion is inversely proportional to the depth of the initial defect and directly proportional to the width of the initial defect.And it was found that the larger the surface area of the initial microdefects, the greater the damage expansion speed and depth.At the same time, by comparing the change rule of the dot center temperature with the damage expansion speed, it is found that the damage expansion speed caused by the microdefect is consistent with the rising speed of the point center temperature.
A rate-adaptive multilevel coded modulation (RA-MLC) scheme based on fixed code length and a corresponding decoding scheme is proposed. RA-MLC scheme combines the multilevel coded and modulation technology with the binary linear block code at the transmitter. Bits division, coding, optional interleaving, and modulation are carried out by the preset rule, then transmitted through standard single mode fiber span equal to 100 km. The receiver improves the accuracy of decoding by means of soft information passing through different layers, which enhances the performance. Simulations are carried out in an intensity modulation-direct detection optical communication system using MATLAB®. Results show that the RA-MLC scheme can achieve bit error rate of 1E-5 when optical signal-to-noise ratio is 20.7 dB. It also reduced the number of decoders by 72% and realized 22 rate adaptation without significantly increasing the computing time. The coding gain is increased by 7.3 dB at BER=1E-3.
A novel training sequence is designed for the space division multiplexed fiber-optic transmission system in this paper. The training block is consisting of segmented sequence, which can be used to compensate time offset and distortion (such as dispersion) in the transmission link. The channel function can be obtained by one tap equalization in the receiver side. This paper designs the training sequence by adjusting the length of the training signals and implementing matrix transformation, to obtain the coefficient of equalizer for channel detect and equalization. This new training sequence reduces system complexity and improves transmission efficiency at the same time. Compared with blind equalization, the matrix transformation based training sequence can reduce system complexity, and perform targeted equalization to the mechanism of mode coupling in the space division optical fiber system. As a result, it can effectively improve signal transmission quality and reduce bit error rate.
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