Monitoring Flue-Cured Tobacco Leaf Chlorophyll Content under Different Light Qualities by Hyperspectral Reflectance

Rapid assessment of foliar chlorophyll content in tobacco is critical for assessment of growth and precise management to improve quality and yield while minimizing adverse environmental impact. Our objective is to develop a precise agricultural practice predicting tobacco-leaf chlorophyll-a content. Reflectance experiments have been conducted on flue-cured tobacco over 3 consecutive years under different light quality. Leaf hyperspectral reflectance and chlorophyll-a content data have been collected at 15-day intervals from 30 days after transplant until harvesting. We identified the central band that is sensitive to tobacco-leaf chlorophyll-a content and the optimum wavelength combinations for establishing new spectral indices (simple ratio index, RVI;normalized difference vegetation index, NDVI;and simple difference vegetation index, DVI). We then established linear and BackPropagation (BP) neural network models to estimate chlorophyll-a content. The central bands for leaf chlorophyll-a content are concentrated in the visible range (410 - 680 nm) in combination with the shortwave infrared range (1900 - 2400 nm). The optimum spectral range for the spectral band combinations RVI, NDVI, and DVI are 440 and 470 nm, 440 and 470 nm, and 440 and 460 nm, respectively. The linear RVI, NDVI, and DVI models, SMLR model and the BP neural network model have respective R2 values of 0.76, 0.77, 0.69, 0.78 and 0.86, and root mean square error values of 0.63, 1.60, 1.59, 2.04 and 0.05 mg chlorophyll-a/g (fresh weight), respectively. Our results identified chlorophyll-a sensitive spectral regions and new indices facilitate a rapid, non-destructive field estimation of leaf chlorophyll-a content for tobacco.

Exploration and Research on Fault Maintenance System of New Generation Weather Radar

In order to improve the standardization, specialization, intelligence and timeliness of the new generation weather radar fault repair, the technical threshold of radar fault repair is greatly reduced, so that the general operators can carry out radar fault repair work. In order to achieve this goal, this paper designs a new generation weather radar fault repair system, which aims to solve two problems: one is to solve the causes and locations of the new generation weather radar faults which can be quickly and accurately detected and diagnosed[1];the other is to solve the problem that the grass-roots radar operational staff are inexperienced in maintenance and will not be repaired, and to provide visual through the maintenance system. Maintenance methods and steps with expert intelligence level [2], so that general radar operators can operate radar fault repair according to video steps, and have the technical level of maintenance experts, to achieve breakthroughs in technical difficulties of radar fault repair, to achieve both disease detection and treatment effect, to improve the efficiency of the use of new generation weather radar and to achieve modern technical equipment support. Chemistry plays an important role and significance.

Design Scheme of Electric Lifting Workbench for Maintenance of Aerometer in Observation Field

The wind speed and wind direction meter of meteorological station is installed on the wind meter pole 10 meters high from the observation site, which also causes some difficulties for the maintenance of the wind speed and wind direction meter in the later period. Based on this situation, an electric lifting worktable (referred to as the electric lifting worktable) is specially designed for the maintenance of wind meters in meteorological observation sites. It can lift the maintenance personnel and equipment and tools to a height convenient for work, and then grasp the wind meter pole through the mechanical arm. It can be operated by a single person, thus getting rid of the traditional dimension by climbing the wind meter pole or releasing the wind meter pole. The present situation of repairing has the characteristics of saving manpower and easy operation, which is conducive to improving work efficiency and reducing work intensity. It also greatly guarantees the safety of maintenance personnel, and has good practicability and extensive popularization value.

腔内修复急性Stanford B型主动脉夹层后支架远端主动脉重塑的因素分析

目的探究急性Stanford B型主动脉夹层患者行胸主动脉腔内修复术(thoracic endovascular aortic repair,TEVAR)后支架远端主动脉重塑不良的影响因素。方法回顾性收集2015年1月至2020年12月于我科接受TEVAR治疗的急性Stanford B型主动脉夹层患者的临床资料,观察支架远端多平面真假腔变化情况并分析支架远端主动脉重塑不良的影响因素。结果共82例患者入组,其中58例(70.7%)患有高血压,57例(69.5%)夹层延伸至髂动脉,随访期间15例(18.3%)患者支架远端出现假腔扩大。假腔扩大组支架主体远端与主动脉角度、腹腔干上方破口数、术后剩余破口数及末次随访时Ⅰ型内漏人数均大于假腔未扩大组,假腔扩大组假腔内血栓长度则小于假腔未扩大组,以上差异具有统计学意义(均P<0.05)。多因素分析显示支架主体远端与主动脉角度过大(OR=1.282,95%CI:1.104~1.486,P=0.001)、术后仍存在较多破口(OR=3.282,95%CI:1.035~10.401,P=0.043)是TEVAR术后主动脉重塑不良的危险因素。结论支架主体远端与主动脉角度过大、术后剩余破口较多是TEVAR术后支架远端主动脉重塑不良的危险因素。

A Micro S-Shaped Optical Fiber Temperature Sensor Based on Dislocation Fiber Splice

We fabricated a simple, compact, and stable temperature sensor based on an S-shaped dislocated optical fiber. The dislocation optical fiber has two splice points, and we obtained the optimal parameters based on the theory and our experiment, such as the dislocation amount and length of the dislocation optical fiber. According to the relationship between the temperature and the peak wavelength shift, the temperature of the environment can be obtained. Then, we made this fiber a micro bending as S-shape between the two dislocation points, and the S-shaped micro bending part could release stress with the change in temperature and reduce the effect of stress on the temperature measurement. This structure could solve the problem of sensor distortion caused by the cross response of temperature and stress. We measured the S-shaped dislocation fiber sensor and the dislocation fiber without S-shape under the same environment and conditions, and the S-shaped dislocation fiber had the advantages of the stable reliability and good linearity.