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排序方式: 共有7073条查询结果,搜索用时 15 毫秒
1.
死亡风险预测指根据病人临床体征监测数据来预测未来一段时间的死亡风险。对于ICU病患,通过死亡风险预测可以有针对性地对病人做出临床诊断,以及合理安排有限的医疗资源。基于临床使用的MEWS和Glasgow昏迷评分量表,针对ICU病人临床监测的17项生理参数,提出一种基于多通道的ICU脑血管疾病死亡风险预测模型。引入多通道概念应用于BiLSTM模型,用于突出每个生理参数对死亡风险预测的作用。采用Attention机制用于提高模型预测精度。实验数据来自MIMIC [Ⅲ]数据库,从中提取3?080位脑血管疾病患者的16?260条记录用于此次研究,除了六组超参数实验之外,将所提模型与LSTM、Multichannel-BiLSTM、逻辑回归(logistic regression)和支持向量机(support vector machine, SVM)四种模型进行了对比分析,准确率Accuracy、灵敏度Sensitive、特异性Specificity、AUC-ROC和AUC-PRC作为评价指标,实验结果表明,所提模型性能优于其他模型,AUC值达到94.3%。 相似文献
2.
Yafei Liu Zhilong Fu Xingyu Chen Yaxin Wei Bo Zhang Aimin Chang 《Journal of the American Ceramic Society》2021,104(5):2134-2142
Rare-earth ions doped Ca0.9R0.1CeNbMoO8 (R = Y, Sm, Nd, La) ceramics have been successfully prepared by solid-state method, and their modifications to the microstructure and electrical properties are also investigated. The rare-earth ions doped ceramics exhibit the scheelite structure. With the increase in the radius of rare-earth ions, the lattice distortion and bond interaction will be enhanced, and the consistency of grain size will be reduced. The ceramics exhibit negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K-1273 K, and the activation energy decreases with the increase of the radius of rare-earth ions. Rare-earth ions doping can increase the content of Ce3+ ions and promote the conductivity of ceramics. Except for Sm3+-doped ceramics, the high-temperature aging rate of other ceramics is less than 2%. The existence of some metastable Sm2+ ions in Sm3+-doped ceramics not only increases the activation energy, but also reduces the high-temperature stability of the ceramics. 相似文献
3.
Yingcai Bi Menglu Lan Jiaxin Li Shupeng Lai Ben M. Chen 《Asian journal of control》2019,21(4):1732-1744
Micro Aerial Vehicles (MAVs) have great potentials to be applied for indoor search and rescue missions. In this paper, we propose a modular lightweight design of an autonomous MAV with integrated hardware and software. The MAV is equipped with the 2D laser scanner, camera, mission computer and flight controller, running all the computation onboard in real time. The onboard perception system includes a laser‐based SLAM module and a custom‐designed visual detection module. A dual Kalman filter design provides robust state estimation by multiple sensor fusion. Specifically, the fusion module provides robust altitude measurement in the circumstance of surface changing. In addition, indoor‐outdoor transition is explicitly handled by the fusion module. In order to efficiently navigate through obstacles and adapt to multiple tasks, a task tree‐based mission planning method is seamlessly integrated with path planning and control modules. The MAV is capable of searching and rescuing victims from unknown indoor environments effectively. It was validated by our award‐winning performance at the 2017 International Micro Air Vehicle Competition (IMAV 2017), held in Toulouse, France. The performance video is available on https://youtu.be/8H19ppS_VXM . 相似文献
4.
Isopimaric acid is a typical rosin compound and can account for 30% of the total mass of slash pine rosin. The molecular structure of isopimaric acid derivatives features an unsaturated double bond at the C13 position, opening up the possibility of their industrial polymerization. In this study, isopimaric acid (95.4%), methyl isopimarate (99.5%), and allyl isopimarate (95.1%) were prepared as highly pure monomers. New experimental results are presented and mechanisms based on the investigation of free-radical polymerization under UV irradiation are proposed. New rosin monomers for potential value-added utilization of woody biomass are also identified. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47817. 相似文献
5.
以丙烯腈和苯甲醇为原料,浓硫酸作催化剂,合成了N-苄基丙烯酰胺(N-BAA)。考察了反应温度、反应时间和催化剂用量等因素对产物收率的影响,得出了最佳反应条件:n(丙烯腈):n(苯甲醇):n(浓硫酸)=3:1:1.2,反应时间3h,反应温度60℃。在最佳条件下,N-BAA的收率可达92%。每100g粗产物用10%氢氧化钠溶液提纯,精制产物纯度可达99.80%,熔点为64~65℃。通过红外光谱对产物结构进行了表征。 相似文献
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研究了基于EDGE系统接收机中信道估计的实现方案,并对算法的各项性能做出评估。首先论述了算法的采用及其理论依据。接着,说明了信道预估计的原理及方法。最后,针对MAT-LAB及 DSP上的仿真结果,比较了各项系数对于系统性能改善所具有的影响和作用,对系统特性作了较为详细的分析总结。 相似文献
9.
以葛洲坝水力发电厂主要自动化技术应用与设备改造为线索,重点回顾 了该厂实现计算机实时监控、全面提高综合自动化水平的历程;全面总结了该厂为实现“无 人值班”(少人值守)而进行的自动化设备换型改造情况和自动化新技术的应用情况;简要 阐述了自动化技术应用给该厂在运行和管理方面带来的深刻变化;展望了该厂未来自动化技 术应用的前景。 相似文献
10.
Group-blind multiuser detectors for uplink code-division multiple-access (CDMA) were recently developed by Wang and Host-Madsen. These detectors make use of the spreading sequences of known users to construct a group constraint to suppress the intracell interference. However, such techniques demand the estimation of the multipath channels and the delays of the known users. In this paper, several improved blind linear detectors are developed for CDMA in fading multipath channels. The proposed detectors utilize the correlation information between consecutively received signals to generate the corresponding group constraint. It is shown that by incorporating this group constraint, the proposed detectors can provide different performance gains in both uplink and downlink environments. Compared with the previously reported group-blind detectors, our new methods only need to estimate the multipath channel of the desired user and do not require the channel estimation of other users. Simulation results demonstrate that the proposed detectors outperform the conventional blind linear multiuser detectors. 相似文献