按时间循环控制电路的应用及设计

介绍了几种按时间循环控制的电路并举例说明常见的按时间顺序循环控制的方法，概述了如何按要求组成控制电路的设计方法。     

荷叶黄酮和生物碱的提纯及调节血脂作用比较

荷叶有较好的调节血脂功效,其主要活性组分是生物碱和黄酮类化合物,但它们各自在调节血脂中作用并不清楚,通过对荷叶黄酮和生物碱提取、分离和纯化,并用两分离组分进行大鼠动物实验,比较它们的调节血脂功效.结果表明:荷叶浸膏、荷叶生物碱对调节血脂中甘油三酯(TG)的指标有极显著作用,荷叶黄酮对调节血脂中甘油三酯的有显著作用,同样剂量生药提炼的生物碱明显优于荷叶黄酮的降血脂功效.     

茶树花多糖提取工艺研究

用常规水浴浸提法来提取茶树花中的多糖,研究了浸提温度、时间、料液比、次数等因素对多糖得率的影响.通过正交试验确定了最佳提取参数.结果表明e影响茶树花多糖浸提各因素的主次顺序为固液比、时间、温度,最佳提取工艺为:温度90℃、时间120min、料液比1:40,在此工艺条件下多糖提取得率2.126%.试验结果为深入研究和开发利用茶树花资源提供了依据.     

基于改进YOLOv5算法的道路伤损检测

道路伤损检测是道路养护过程中的重要基础性环节，传统道路伤损检测方法存在检测成本高且效率低的缺陷。为准确快速检测道路伤损状况，提出了一种基于YOLOv5改进的道路伤损检测模型YOLO-C-α。通过引入注意力机制CBAM模块，提高检测模型的特征提取及特征融合能力，改善模型对道路损伤小目标的漏检问题；引入α-IoU损失函数替换原始网络CIOU损失函数，降低预测框的回归损失，提升预测框的定位精度。基于RDD2020道路伤损检测数据集展开对比实验，结果显示：YOLO-C-α模型平均准确度达到60.3%,相比于原始模型平均精度提升1.4%,其F1值为60.2,相比于原始模型提升1%,且对于不同天气状况下的路面损伤均有较高的检测性能，实验环境每张图片的检测速度为6.3 ms,模型大小40.6 Mb。结果表明：本文基于YOLOv5m改进的算法抗干扰能力较强，能更准确地检测出多种天气状况下道路伤损目标，可为道路伤损实时检测及智慧化道路养护提供参考。     

Liver and spleen enhancement after intravenous injection of carboxydextran magnetite: effect of dose, delay of imaging, and field strength in an ex vivo model

It has been predicted that liver and spleen enhancement after administration of superparamagnetic contrast agents may be different, depending on the strength of the main magnetic field. With the use of an ex vivo model, we investigated at 0.3, 0.5, and 1.5 T the effects on liver and spleen signal intensity of 5, 15, and 45 mumol/kg body weight of dextran magnetite (SHU 555A) in 54 rats. Nine rats served as controls. At different time delays since injection, the animals were killed, and after perfusion with saline, the liver, brain, and spleen were fixed in formalin. The specimens were embedded in an agar gel matrix and imaged with inversion recovery T1-weighted, proton density spin echo, and T2*-weighted gradient recalled echo (GRE) sequences. At each magnetic field strength, peak liver and spleen signal loss increased with increasing dose of the contrast medium. Signal loss was significantly more conspicuous after a dose of 15 than 5 mumol/kg body weight, but not after a dose of 45 compared with 15 mumol/kg. No signal change was observed in the brain. GRE images showed higher enhancement than proton density-weighted spin echo and inversion recovery images but were noisier. The enhancement showed a plateau between 30 min and 24 hours. Only the signal decrease of the liver after a low dose of contrast medium on GRE images was significantly higher (p < 0.01) at 1.5 than at 0.5 and 0.3 T. Other differences in respect to the field strength were less significant (p < 0.05) or nonsignificant. Differences in the spleen enhancement were nonsignificant. SHU 555A at a dose of 15 mumol/kg is an efficient intracellular contrast agent for liver and spleen at low, mid, and high field strength. Proton density spin echo images are probably the sequence of choice to exploit SHU 555A contrast effects and a wide time window for imaging after its intravenous injection does exist.     

基于城市信息单元的多源时空数据融合框架

建设智慧城市可有效提升城市治理与运行能力、打破城市发展困境。为探索如何基于物理-数字空间交融中的时空大数据提供面向城市管理的智能服务,该文在解析多源、多维、异构时空大数据语义关系的基础上,提出多源时空大数据透明融合框架。为实现这一目标,该文进一步提出“城市信息单元”的概念作为构建物理-数字空间交融的数据组织基础,首先,对多源、多维、异构时空大数据进行主动汇集、语义解析,完成地理知识时空构建,依据唯一数据编码,将数据信息映射至城市信息单元;然后,建立数据匹配模型和关联模型,搭建数据透明融合框架,结合多源异构数据要素匹配技术,构建时空数据透明融合规则库;最后,在众多融合方法的支持下,实现城市实体与时空多源时空数据的透明融合。借助城市信息单元与数据编码,实现城市实体与时空大数据动态融合方法体系,进而为用户提供智能化信息服务。     

结合用户特征的政务服务协同过滤推荐方法

为推荐政务服务相关事项,提高用户办事效率与政府服务水平,该文提出一种推荐算法,即结合用户特征的政务服务协同过滤推荐方法。该方法为解决传统协同过滤未考虑用户属性的问题,将用户画像技术与其相结合。首先,建立政务服务用户画像;然后,采用奇异值度量分析方法融合用户画像与基于用户的协同过滤算法,使特征属性参与相似度计算,改善用户之间的相似性,并解决数据稀疏性的问题,使推荐结果更具实际意义;最后,计算政务服务事项预测得分,将得分最高的 TOP-N 推荐给用户。在实验部分,该文利用某市企业法人的政务服务真实数据进行验证。结果显示,该算法能够满足政务服务推荐的个性化要求,预测准确性较高。     

18Pin和24Pin的DVI线有何区别

DVI接口标准有两种,分别是DVI—Digital（DVI—D,纯数字DVI接口）与DVI—Integrated（DVI—I,整合DVI接口）。     

Milking time and risk of over-milking can be decreased with early teat cup removal based on udder quarter milk flow without loss in milk yield

Increasing the milk flow rate at which milking is terminated can shorten milking time and increase milking efficiency. The effects on milk yield and composition have not been fully investigated when the take-off is set at the udder quarter level and independent of feeding during milking. The objective of this study was to investigate the effect of 3 take-off levels at the udder quarter level (0.06, 0.3, and 0.48 kg/min) applied with or without feeding during milking on milking time, milk yield, the degree of udder emptying, milk composition, and free fatty acids. In this study, 30 cows were allocated into 6 groups, balanced by lactation number, lactation stage, and milk yield, and subjected to a 3 × 2 factorial arrangement of treatments using a Latin square design. Treatments were applied for 1 wk each. This study demonstrated milking time could be reduced by applying up to a take-off level of 0.48 kg/min on udder quarter level without losing milk yield or compromising milk composition or udder health.     

微坑穴共聚酯纤维的可纺性研究

研究了微坑穴共聚酯纤维在常规纺丝速度下纺丝熔体的流变行为和可纺性 ,并着重讨论了在熔融挤出过程中切片质量、熔体加工条件及流变参数对纺丝熔体细流强度、纺丝成形的稳定性和纤维质量的影响。