相序指示器的最佳参数设计

利用PSpice电路仿真软件,对灯泡指示相序仪中的元件参数进行了全面的扫描分析。依据这些扫描曲线,从理论和工程实用的角度,给出了元件参数的最佳选取范围。研究结果对理解相序仪的本质和正确使用相序仪具有指导作用。     

大型螺旋叶片的成形工艺分析及模具设计

通过分析螺旋曲面零件的工艺特点及螺旋曲面成形的变形过程，总结螺旋曲面成形后的回弹规律，介绍了一种焊接结构的大尺寸螺旋叶片压形模的设计及制造工艺。     

Development of a subacute ruminal acidosis risk score and its prediction using milk mid-infrared spectra in early-lactation cows

A routine monitoring for subacute ruminal acidosis (SARA) on the individual level could support the minimization of economic losses and the ensuring of animal welfare in dairy cows. The objectives of this study were (1) to develop a SARA risk score (SRS) by combining information from different data acquisition systems to generate an integrative indicator trait, (2) the investigation of associations of the SRS with feed analysis data, blood characteristics, performance data, and milk composition, including the fatty acid (FA) profile, (3) the development of a milk mid-infrared (MIR) spectra-based prediction equation for this novel reference trait SRS, and (4) its application to an external data set consisting of MIR data of test day records to investigate the association between the MIR-based predictions of the SRS and the milk FA profile. The primary data set, which was used for the objectives (1) to (3), consisted of data collected from 10 commercial farms with a total of 100 Holstein cows in early lactation. The data comprised barn climate parameters, pH and temperature logging from intrareticular measurement boluses, as well as jaw movement and locomotion behavior recordings of noseband-sensor halters and pedometers. Further sampling and data collection included feed samples, blood samples, milk performance, and milk samples, whereof the latter were used to get the milk MIR spectra and to estimate the main milk components, the milk FA profile, and the lactoferrin content. Because all measurements were characterized by different temporal resolutions, the data preparation consisted of an aggregation into values on a daily basis and merging it into one data set. For the development of the SRS, a total of 7 traits were selected, which were derived from measurements of pH and temperature in the reticulum, chewing behavior, and milk yield. After adjustment for fixed effects and standardization, these 7 traits were combined into the SRS using a linear combination and directional weights based on current knowledge derived from literature studies. The secondary data set was used for objective (4) and consisted of test day records of the entire herds, including performance data, milk MIR spectra and MIR-predicted FA. At farm level, it could be shown that diets with higher proportions of concentrated feed resulted in both lower daily mean pH and higher SRS values. On the individual level, an increased SRS could be associated with a modified FA profile (e.g., lower levels of short- and medium-chain FA, higher levels of C17:0, odd- and branched-chain FA). Furthermore, a milk MIR-based partial least squares regression model with a moderate predictability was established for the SRS. This work provides the basis for the development of routine SARA monitoring and demonstrates the high potential of milk composition-based assessment of the health status of lactating cows.     

基于深度学习的文本到图像生成方法综述

文本到图像生成方法采用自然语言与图像集特征的映射方式,根据自然语言描述生成相应图像,利用语言属性智能地实现视觉图像的通用性表达.基于卷积神经网络的深度学习技术是当前文本到图像生成的主流方法,为系统地了解该领域的研究现状和发展趋势,按照模型构建及技术实现形式的不同,将已有的技术方法分为直接图像法、分层体系结构法、注意力机...     

大型引水管线施工控制网精度指标的推算与大地网的应用

介绍长距离大口径管线施工控制测量中解决问题的方法。     

MPEG-4 video verification model: Status and directions

This article describes the current status and future directions of the emerging ISO MPEG-4 audiovisual coding standard. The article first presents an overview of the different aspects of the standard and then focuses on the video coding aspects. The current status of the Video Verification Model (VM) (a completely defined encoder and decoder specification) is described in detail and its performance is presented. The new functionalities supported by this emerging standard and their potential applications are highlighted. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 468–479, 1997     

变工况下航空逆变器健康评估方法研究

工况的变化会引起功率变换器电路健康表征参数随之变化,导致无法判断健康表征参数是因电路性能的退化还是因工况的变化引起的。针对该关键问题,以航空逆变器为研究对象,首先采用多评价指标优选模型优选出相关敏感的健康表征参数;然后基于极限学习机建立工况-无故障情况下健康表征参数映射模型;最后基于当前健康表征参数与映射模型输出的健康表征参数之间的相对变化量构建考虑工况条件的电路健康指标,实现不同工况下航空逆变器的健康评估。实验结果表明,该评估方法可以有效减小工况变化对健康指标的影响。在变工况情况下,相比于直接基于欧氏距离构建健康指标的评估方法,平均绝对误差（Mean Absolute Error,MAE）和均方根误差（Root-Mean-Square Error,RMSE）分别降低了64.4%、66.8%。     

基于电网成效贡献度的储备项目量化评价方法及优选排序

“十三五”以来,随着电网公司经营形势日趋严峻,如何科学合理决策电网投资,提高项目安排精准度对企业可持续发展至关重要。针对电网基建储备项目特点,从经济性、安全性、协调性等方面研究电网基建储备项目对电网发展的贡献度,建立了一套科学合理的储备项目评价指标体系。并通过分析每个电网储备项目在经济性、安全性、协调性等方面对整个电网成效评估指标的提升情况,提出了储备项目对电网整体的综合贡献度计算方法,并以单位投资综合贡献度为基础,考虑电网建设时序的影响,构建了电网储备项目的动态优选排序模型。最后以某地区10 kV配电网为基础,对某地区2020年新建或扩建10 kV级别的储备项目进行评估和优选,验证所提电网储备项目评估和优选排序方法的科学性与合理性。     

氧指示剂在香料微胶囊壁材筛选中的应用

以海藻酸钠（SA）、甲基纤维素（MC）、羧甲基壳聚糖（CMC）作为微胶囊壁材,亚甲基蓝（MB）/TiO2/甘油（Gly）作为氧指示剂,制备了6种微胶囊氧指示剂复合薄膜。根据氧指示剂复合薄膜激活、回色以及重复利用性筛选合适的屏氧壁材体系。当MC的质量浓度为20 g/L,MB、TiO2、Gly用量分别为0.05 g、1 g和0.5 mL时,MB/TiO2/Gly/MC氧指示剂复合薄膜光催化激活效率最佳。在空气湿度为75%、温度为35 ℃条件下,MC/SA/MC和MC/CMC/SA氧指示剂复合薄膜在10 h的回色率分别为28.7%和27.9%,且回色时变化较均匀;重复使用3次,MC/SA/MC和MC/CMC/SA氧指示剂复合薄膜的回色率仅分别下降了0.8%和1.0%,说明这两种壁材体系是屏氧良好的香料壁材。将这两种壁材体系通过喷雾干燥法包埋玫瑰精油芯材制备香料微胶囊,存放7 d后,包埋在MC/CMC/SA中的芯材有新物质出现而MC/SA/MC中无新物质,说明MC/SA/MC体系对精油有更好的保护作用。