当前,土地沙漠化已成为全球十大生态环境问题之一,严重威胁着众多国家和地区。为有效监测沙漠化动态,本研究基于Landsat遥感影像,通过辐射定标、大气校正等预处理算法获取沙漠区域影像。本研究首先采用人工目视解译方法对典型沙漠边界...当前,土地沙漠化已成为全球十大生态环境问题之一,严重威胁着众多国家和地区。为有效监测沙漠化动态,本研究基于Landsat遥感影像,通过辐射定标、大气校正等预处理算法获取沙漠区域影像。本研究首先采用人工目视解译方法对典型沙漠边界区域进行标注,构建训练样本;随后基于结构状态空间对偶的双分支编码沙漠分割模型提取大范围沙漠边界信息;最终形成2000–2020年每5年一次的中国沙漠边界数据集。本数据集涉及中国八大沙漠,即腾格里沙漠、塔克拉玛干沙漠、巴丹吉林沙漠、库布齐沙漠、乌兰布和沙漠、库姆塔格沙漠、古尔班通古特沙漠、柴达木盆地沙漠。在质量控制方面,通过引入Overall Accuracy(OA)、Mean Intersection over Union(MioU)、Mean Pixel Accuracy(MPA)、Mean Recall(MRecall)和Mean F1 Score(MF1)等指标进行精度评估,最终OA达98.78%,MIou达97.58%,MPA达98.77%,MRecall达98.77%,MF1达98.77%。本数据集在沙漠化监测、环境保护、资源管理等领域具有重要的应用价值,为沙漠化研究提供了有力的数据支撑。展开更多
2P DC 2000 V框架隔离开关适用于新一代的新能源系统。针对DC 2000 V框架隔离开关设计,在主弧触头的强制隔离上,通过增加绝缘件,将电弧集中于弧触头,提升分断能力;在触头时序可靠控制方面,依据不同电流下弧柱电压和残余电压关系,确定合...2P DC 2000 V框架隔离开关适用于新一代的新能源系统。针对DC 2000 V框架隔离开关设计,在主弧触头的强制隔离上,通过增加绝缘件,将电弧集中于弧触头,提升分断能力;在触头时序可靠控制方面,依据不同电流下弧柱电压和残余电压关系,确定合适时序差,同时考虑触头磨损影响,保证电弧可靠熄灭;结合高电压动态绝缘仿真和直流弧压精控计算,精确保证产品的可靠性。经过试验验证,新的2P DC 2000 V框架隔离开关符合新老标准要求。展开更多
背景:随着社会人口进入老龄化,牙齿缺损问题日益凸显。当前,牙列缺损的修复方式包括固定义齿、可摘义齿和种植辅助修复。尽管固定义齿和种植修复为首选,但考虑到经济、健康状况和舒适度等因素,可摘式义齿仍是合适的选择。方法:文章重点...背景:随着社会人口进入老龄化,牙齿缺损问题日益凸显。当前,牙列缺损的修复方式包括固定义齿、可摘义齿和种植辅助修复。尽管固定义齿和种植修复为首选,但考虑到经济、健康状况和舒适度等因素,可摘式义齿仍是合适的选择。方法:文章重点分析了钴铬合金、Vitallium 2000、纯钛和PEEK材料在可摘局部义齿中的应用现状,包括机械性能、生物相容性、临床效果和经济性。结果:钴铬合金因其高强度和良好的抗腐蚀性,适用于强咀嚼力患者,但其较重且美学效果差;纯钛材料具有极佳的生物相容性,适合金属过敏患者,然而强度较低,无法承受较大负荷;Vitallium 2000具备高强度和抗腐蚀性,适合高负荷患者,但成本较高;PEEK强度较低,但在美学效果和生物相容性上表现优异,适用于金属过敏患者和美学要求较高的患者。讨论:材料的选择应根据患者的需求、口腔健康状况以及修复体的功能要求做出综合考虑。展望:未来的研究将更加关注机械性能的改进、3D打印技术的应用以及智能化材料技术的进展,以实现更加个性化和智能化的义齿修复。Background: With the aging of the population, the issue of tooth loss has become increasingly prominent. Current methods for restoring dental defects include fixed dentures, removable dentures, and implant-supported restorations. Although fixed dentures and implant restorations are the preferred options, removable dentures remain a suitable choice considering factors such as cost, health condition, and comfort. Methods: This article focuses on the application status of cobalt-chromium alloy, Vitallium 2000, pure titanium, and PEEK materials in removable partial dentures, including their mechanical properties, biocompatibility, clinical effects, and cost-effectiveness. Results: Cobalt-chromium alloy, with its high strength and excellent corrosion resistance, is suitable for patients with strong chewing forces, but it is relatively heavy and has poor aesthetic effects. Pure titanium has excellent biocompatibility, making it ideal for patients with metal allergies, but its low strength makes it unable to bear large loads. Vitallium 2000 offers high strength and corrosion resistance, making it suitable for high-load patients, but it is costly. PEEK has lower strength but excels in aesthetic effects and biocompatibility, making it suitable for patients with metal allergies and those with higher aesthetic demands. Discussion: The choice of material should be based on a comprehensive consideration of the patient's needs, oral health condition, and the functional requirements of the restoration. Outlook: Future research will focus more on improving mechanical properties, applying 3D printing technology, and advancing smart material technologies to achieve more personalized and intelligent denture restorations.展开更多
文摘当前,土地沙漠化已成为全球十大生态环境问题之一,严重威胁着众多国家和地区。为有效监测沙漠化动态,本研究基于Landsat遥感影像,通过辐射定标、大气校正等预处理算法获取沙漠区域影像。本研究首先采用人工目视解译方法对典型沙漠边界区域进行标注,构建训练样本;随后基于结构状态空间对偶的双分支编码沙漠分割模型提取大范围沙漠边界信息;最终形成2000–2020年每5年一次的中国沙漠边界数据集。本数据集涉及中国八大沙漠,即腾格里沙漠、塔克拉玛干沙漠、巴丹吉林沙漠、库布齐沙漠、乌兰布和沙漠、库姆塔格沙漠、古尔班通古特沙漠、柴达木盆地沙漠。在质量控制方面,通过引入Overall Accuracy(OA)、Mean Intersection over Union(MioU)、Mean Pixel Accuracy(MPA)、Mean Recall(MRecall)和Mean F1 Score(MF1)等指标进行精度评估,最终OA达98.78%,MIou达97.58%,MPA达98.77%,MRecall达98.77%,MF1达98.77%。本数据集在沙漠化监测、环境保护、资源管理等领域具有重要的应用价值,为沙漠化研究提供了有力的数据支撑。
文摘2P DC 2000 V框架隔离开关适用于新一代的新能源系统。针对DC 2000 V框架隔离开关设计,在主弧触头的强制隔离上,通过增加绝缘件,将电弧集中于弧触头,提升分断能力;在触头时序可靠控制方面,依据不同电流下弧柱电压和残余电压关系,确定合适时序差,同时考虑触头磨损影响,保证电弧可靠熄灭;结合高电压动态绝缘仿真和直流弧压精控计算,精确保证产品的可靠性。经过试验验证,新的2P DC 2000 V框架隔离开关符合新老标准要求。
文摘背景:随着社会人口进入老龄化,牙齿缺损问题日益凸显。当前,牙列缺损的修复方式包括固定义齿、可摘义齿和种植辅助修复。尽管固定义齿和种植修复为首选,但考虑到经济、健康状况和舒适度等因素,可摘式义齿仍是合适的选择。方法:文章重点分析了钴铬合金、Vitallium 2000、纯钛和PEEK材料在可摘局部义齿中的应用现状,包括机械性能、生物相容性、临床效果和经济性。结果:钴铬合金因其高强度和良好的抗腐蚀性,适用于强咀嚼力患者,但其较重且美学效果差;纯钛材料具有极佳的生物相容性,适合金属过敏患者,然而强度较低,无法承受较大负荷;Vitallium 2000具备高强度和抗腐蚀性,适合高负荷患者,但成本较高;PEEK强度较低,但在美学效果和生物相容性上表现优异,适用于金属过敏患者和美学要求较高的患者。讨论:材料的选择应根据患者的需求、口腔健康状况以及修复体的功能要求做出综合考虑。展望:未来的研究将更加关注机械性能的改进、3D打印技术的应用以及智能化材料技术的进展,以实现更加个性化和智能化的义齿修复。Background: With the aging of the population, the issue of tooth loss has become increasingly prominent. Current methods for restoring dental defects include fixed dentures, removable dentures, and implant-supported restorations. Although fixed dentures and implant restorations are the preferred options, removable dentures remain a suitable choice considering factors such as cost, health condition, and comfort. Methods: This article focuses on the application status of cobalt-chromium alloy, Vitallium 2000, pure titanium, and PEEK materials in removable partial dentures, including their mechanical properties, biocompatibility, clinical effects, and cost-effectiveness. Results: Cobalt-chromium alloy, with its high strength and excellent corrosion resistance, is suitable for patients with strong chewing forces, but it is relatively heavy and has poor aesthetic effects. Pure titanium has excellent biocompatibility, making it ideal for patients with metal allergies, but its low strength makes it unable to bear large loads. Vitallium 2000 offers high strength and corrosion resistance, making it suitable for high-load patients, but it is costly. PEEK has lower strength but excels in aesthetic effects and biocompatibility, making it suitable for patients with metal allergies and those with higher aesthetic demands. Discussion: The choice of material should be based on a comprehensive consideration of the patient's needs, oral health condition, and the functional requirements of the restoration. Outlook: Future research will focus more on improving mechanical properties, applying 3D printing technology, and advancing smart material technologies to achieve more personalized and intelligent denture restorations.
