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Monitoring gas-and particulate-phase short-chain polychlorinated paraffins in the urban air of Dalian by a self-developed passive sampler
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作者 Yifan Wang Xiuhua Zhu +7 位作者 ,Yuan Gao Hao Bai Pengyuan Wang Jiping Chen ,Heping Yuan Longxing Wang Xiaoxiao Li Wei Wang 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第6期287-295,共9页
The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume... The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure–property relationship of the sampling rate of PAS1(Rair) for gas-phase SCCPs was studied. From the molecular point of view, Rairwas mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase,lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards. 展开更多
关键词 Ambient air Short-chain POLYCHLORINATED paraf FINS PASSIVE SAMPLER Active sampling PASSIVE sampling
火电厂非能动除灰系统 预览
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作者 刘旭 翟煤源 +2 位作者 张森 王殿军 王明臣 《山东电力技术》 2019年第1期67-70,74共5页
介绍一种新的火电厂除灰系统:将灰库设置在除尘器下,与除尘器合为一体,除尘器中分离出来的干灰,在重力作用下,直接落入灰库,并在除尘器下直接装车外运。系统简单,节约能耗。
关键词 火电厂 非能动 除灰系统
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Misclassification of smoking habits: An updated review of the literature 预览
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作者 Janette S Hamling Katharine J Coombs Peter N Lee 《世界荟萃分析杂志》 2019年第2期31-50,共20页
BACKGROUND Misclassification of smoking habits leads to underestimation of true relationships between diseases and active smoking, and overestimation of true relationships with passive smoking. Information on misclass... BACKGROUND Misclassification of smoking habits leads to underestimation of true relationships between diseases and active smoking, and overestimation of true relationships with passive smoking. Information on misclassification rates can be obtained from studies using cotinine as a marker. AIM To estimate overall misclassification rates based on a review and meta-analysis of the available evidence, and to investigate how misclassification rates depend on other factors. METHODS We searched for studies using cotinine as a marker which involved at least 200 participants and which provided information on high cotinine levels in selfreported non-, never, or ex-smokers or on low levels in self-reported smokers. We estimated overall misclassification rates weighted on sample size and investigated heterogeneity by various study characteristics. Misclassification rates were calculated for two cotinine cut points to distinguish smokers and nonsmokers, the higher cut point intended to distinguish regular smoking. RESULTS After avoiding double counting, 226 reports provided 294 results from 205 studies. A total of 115 results were from North America, 128 from Europe, 25 from Asia and 26 from other countries. A study on 6.2 million life insurance applicants was considered separately. Based on the lower cut point, true current smokers represented 4.96%(95% CI 4.32-5.60%) of reported non-smokers, 3.00%(2.45-3.54%) of reported never smokers, and 10.92%(9.23-12.61%) of reported exsmokers. As percentages of true current smokers, non-, never and ex-smokers formed, respectively, 14.50%(12.36-16.65%), 5.70%(3.20-8.20%), and 8.93%(6.57- 11.29%). Reported current smokers represented 3.65%(2.84-4.45%) of true nonsmokers. There was considerable heterogeneity between misclassification rates. Rates of claiming never smoking were very high in Asian women smokers, the individual studies reporting rates of 12.5%, 22.4%, 33.3%, 54.2% and 66.3%. False claims of quitting were relatively high in pregnant women, in diseased individuals who may rece 展开更多
关键词 MISCLASSIFICATION SMOKING COTININE Cigarettes TOBACCO use E-cigarettes Passive SMOKING BIAS Systematic review Meta-analysis
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Passivity breakdown of 13Cr stainless steel under high chloride and CO2 environment 预览
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作者 Hui-xin Li Da-peng Li +3 位作者 Lei Zhang Ya-wen Wang Xiu-yun Wang Min-xu Lu 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第3期329-336,共8页
Herein, the effect of high chloride ion (Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl^- concentration was ... Herein, the effect of high chloride ion (Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl^- concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl^- concentration on the corrosion potential (Ecorr), passive breakdown potential (Epit), and repassivation potential (Erep). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl^- concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl^- concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model (PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl^- concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film. 展开更多
关键词 13Cr STAINLESS steel electrochemical characterization PITTING corrosion high CHLORIDE concentration PASSIVE film BREAKDOWN
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Evaluation of interaction between Sn and passivated stainless steel through an easy chromaticity approach
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作者 Yan Zhao Jian-jun Guan +3 位作者 Feng Liu Ping Liang Cong-qian Cheng Jie Zhao 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第2期211-218,共8页
The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach.The microstructure of Fe-Sn intermetallics(IMCs)was observed,and their growth was inspected at differenf ti... The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach.The microstructure of Fe-Sn intermetallics(IMCs)was observed,and their growth was inspected at differenf time after the in teract io n.The oxide film on stainless steel exposed in air locally delayed IMC growth,and the chemically passivated film protected stainless steel from Fe-Sn compound formation.To investigate the interaction mechanism,the integrity of passivated films grown on stainless steel was evaluated by chromogenic inspection.The interaction extern was related to colour measurement a*.Results indicated that the measured value of a*from the inspection decreased with the increasing exposure time,and a minimum a*value was found in chemically passivated samples.The tendency of the colour measureme was consistent with the effect of passive film on IMC growth.The in terfacial reaction of passivated stainless steel with Sn was illustrated based on the integrity of the passive films. 展开更多
关键词 STAINLESS steel PASSIVE film CHROMATICITY inspection SN Fe-Sn INTERMETALLICS
Mechanism of Spine Motion About Contact Time in Quadruped Running
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作者 Qi Liu Yannian Bao +3 位作者 Wei Yu Jianming Zhang Chao Li Xinru Xie 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第2期53-60,共8页
The current research of quadruped robot focuses on the quadruped robot with spine motion. Contact time is a very important part of system performance. However, the mechanism of spine motion about contact time has not ... The current research of quadruped robot focuses on the quadruped robot with spine motion. Contact time is a very important part of system performance. However, the mechanism of spine motion about contact time has not been clearly elucidated. In this paper, the e ect of spine motion on contact time is studied deeply from dynamic view.Firstly, a simplified model of the quadruped robot with spine joint is set up, its dynamic equations are derivated, and a method that can generate passive periodic locomotion is proposed. Secondly, according to the vertical spring oscillator model, the two-dimension planar locomotion of the simplified model is regarded as a special vibration in the vertical direction, and the approximate formula of calculating contact time is obtained. Finally, the approximate formula of calculating contact time is verified by the simulation results of passive periodic locomotion, and the e ect of spine motion on contact time is deeply discussed based on the approximate formula of calculating contact time. The discussion proves that spine motion indeed has little e ect on contact time, but spine motion can slightly reduce body pith movement and regulate the leg sti ness in leg contact phase. This research proposes an e ective research method which can be used to study the motion mechanism of the quadruped robot with spine motion,and the mechanism of spine motion about contact time is clearly elucidated which is helpful to set the parameters of mechanical structure and study control algorithm about the quadruped robot with spine motion. 展开更多
关键词 QUADRUPED robot SPINE MOTION PASSIVE locomotion Contact time LEG STI ness
Characterization of Passive Films Formed on As-received and Sensitized AISI 304 Stainless Steel
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作者 Yubo Zhang Hongyun Luo +2 位作者 Qunpeng Zhong Honghui Yu Jinlong Lv 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第2期61-72,共12页
The current research of corrosion resistance of stainless steels mainly focuses on characterization of the passive films by point defect mode and mixed-conduction model. The corrosion resistance of the passive films f... The current research of corrosion resistance of stainless steels mainly focuses on characterization of the passive films by point defect mode and mixed-conduction model. The corrosion resistance of the passive films formed on asreceived and sensitized AISI304 stainless steel in borate bu er solution were evaluated in this paper. The degree of sensitization and corrosion resistance of AISI304 stainless steels was evaluated by double loop electrochemical potentiodynamic reactivation and electrochemical impedance spectroscopy. The passive films formed on the stainless steels were studied by XPS technique. It was found that as-received specimen had higher pitting corrosion potential and corrosion resistance than sensitized one. The Mott-Schottky results showed that sensitized stainless steel had more defects in the passive film than as-received one. The compositions of the passive films were mainly Cr and Fe oxides according to XPS results. 展开更多
关键词 304 STAINLESS steel SENSITIZATION Passive films XPS IMPEDANCE
被动式超低能耗木结构建筑外围护结构节能设计 预览
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作者 姜雷 《科学技术与工程》 北大核心 2019年第8期205-209,共5页
在被动式超低能耗木结构建筑能量损失中外围护结构的传热损失占比最高,为了降低能耗,研究了被动式超低能耗木结构建筑外围护结构节能设计方案。通过标定热箱法对建筑外围护结构保温性进行测试,获取建筑外围护结构传热系数或热阻。分析... 在被动式超低能耗木结构建筑能量损失中外围护结构的传热损失占比最高,为了降低能耗,研究了被动式超低能耗木结构建筑外围护结构节能设计方案。通过标定热箱法对建筑外围护结构保温性进行测试,获取建筑外围护结构传热系数或热阻。分析了建筑外围护外墙、屋顶和外窗,研究了各外围护组成部分的传热系数。将研究的被动式超低能耗木结构建筑当成基准建筑,将其冷热总负荷和各外围护结构节能设计方案全年空调总负荷的差值当成对应组合方案的总负荷节能值,获取节能设计方案。方案2和方案4都是采用的桁架屋顶,方案8采用的是椽檩式屋顶,方案4和方案8的外墙为玻璃纤维保温棉填充墙体,方案2外墙为岩棉填充墙体。三个方案的外窗统一为low-E中空(断热铝窗框)。结果表明:方案4空调总负荷节能值最高,其次是方案2,再次为方案8;方案4能耗低,二氧化碳减排量高,舒适性好。可见桁架屋顶、玻璃纤维保温棉填充墙体、low-E中空(断热铝窗框)外窗组成的外围护结构节能设计方案最优。 展开更多
关键词 被动式 超低能耗 木结构 建筑外围护结构 节能设计
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温控旁路型电池开路保护器的设计
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作者 周芝远 吕世斌 +1 位作者 李富强 范益锋 《电气应用》 2019年第4期120-123,共4页
针对蓄电池的开路故障,根据蓄电池发生开路故障的运行特性,研究设计一种温控旁路型电池开路保护器,可实现自动判断并快速解决电池开路故障,从而保护蓄电池组正常对外供电运行。该开路保护器,采用无源工作方式,利用快恢复功率二极管作为... 针对蓄电池的开路故障,根据蓄电池发生开路故障的运行特性,研究设计一种温控旁路型电池开路保护器,可实现自动判断并快速解决电池开路故障,从而保护蓄电池组正常对外供电运行。该开路保护器,采用无源工作方式,利用快恢复功率二极管作为启动元件来自动判断并短接处理开路故障电池,利用旁路温控开关来解决快恢复严重发热问题,维持长期运行。 展开更多
关键词 蓄电池 开路保护 无源 自动 温控
How to Filter Passive Emotion in English Teaching at Vocational School 预览
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作者 盘蔼然 《校园英语》 2019年第10期66-67,共2页
Nowadays emotional education is widely used in teaching in order to motivate students’ positive feeling towards language acquisition. This paper aims at analyzing the function of filtering passive emotions in English... Nowadays emotional education is widely used in teaching in order to motivate students’ positive feeling towards language acquisition. This paper aims at analyzing the function of filtering passive emotions in English teaching at vocational school from the role of attitude, aptitude and language barrier. 展开更多
关键词 FILTER PASSIVE EMOTION English teaching VOCATIONAL SCHOOL
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带式输送机无源液压调偏装置研究 预览
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作者 张姬 《机械管理开发》 2019年第8期90-91,129,共3页
针对煤矿带式输送机的跑偏问题,从设备的制造、安装和维护等方面对跑偏的发生原因进行了分析,介绍了常用无源和有源调偏方法的特点,分别对无源液压调偏装置的组成结构、调偏过程、调偏工作原理等内容进行了详细研究,最后从多个角度给出... 针对煤矿带式输送机的跑偏问题,从设备的制造、安装和维护等方面对跑偏的发生原因进行了分析,介绍了常用无源和有源调偏方法的特点,分别对无源液压调偏装置的组成结构、调偏过程、调偏工作原理等内容进行了详细研究,最后从多个角度给出了带式输送机调偏控制的技术要点。 展开更多
关键词 煤矿 带式输送机 调偏 无源 液压
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Adaptive Robust Control for a Lower Limbs Rehabilitation Robot Running Under Passive Training Mode 预览
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作者 Xiaolong Chen Han Zhao +1 位作者 Shengchao Zhen Hao Sun 《自动化学报:英文版》 CSCD 2019年第2期493-502,共10页
This paper focuses on the problem of the adaptive robust control of a lower limbs rehabilitation robot(LLRR) that is a nonlinear system running under passive training mode. In reality, uncertainties including modeling... This paper focuses on the problem of the adaptive robust control of a lower limbs rehabilitation robot(LLRR) that is a nonlinear system running under passive training mode. In reality, uncertainties including modeling error, initial condition deviation, friction force and other unknown external disturbances always exist in a LLRR system. So, it is necessary to consider the uncertainties in the unilateral man-machine dynamical model of the LLRR we described. In the dynamical model, uncertainties are(possibly fast) time-varying and bounded. However, the bounds are unknown. Based on the dynamical model, we design an adaptive robust control with an adaptive law that is leakagetype based and on the framework of Udwadia-Kalaba theory to compensate for the uncertainties and to realize tracking control of the LLRR. Furthermore, the effectiveness of designed control is shown with numerical simulations. 展开更多
关键词 Adaptive robust control LOWER LIMBS REHABILITATION ROBOT mechanical system PASSIVE training UNCERTAINTIES
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Penetration Estimation of GMA Backing Welding Based on Weld Pool Geometry Parameters
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作者 Junfen Huang Long Xue +2 位作者 Jiqiang Huang Yong Zou Ke Ma 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第3期134-144,共11页
Penetration estimation is a prerequisite of the automation of backing welding based on vision sensing technology. However, the arc interference in welding process leads to the difficulties of extracting the weld pool ... Penetration estimation is a prerequisite of the automation of backing welding based on vision sensing technology. However, the arc interference in welding process leads to the difficulties of extracting the weld pool characteristic information, which brings great challenges to the penetration estimation. At present, most researches focus on the extraction of weld pool geometry parameters, and the visual sensing systems are complex in structure and complicated in the image processing algorithms. The research of penetration estimation based on weld pool geometry parameters is still in the exploratory stage. The purpose of this paper is to research the relationship between the weld pool geometry parameters and the penetration during backing welding and to estimate penetration using the weld pool geometry parameters. A passive vision sensing test system for gas metal arc (GMA) backing welding was established. An image processing algorithm was developed to extract the weld pool geometry parameters, namely, the area, maximum width and length, half-length, length-width ratio and advancing contact angle (simplified as AWP, MWWP, MLWP, HLWP, LWR and ACA, respectively). The corresponding relationships between the weld pool geometry parameters and the penetration state were explored by analysing their changes with the welding current and speed. The distribution of the weld pool geometry parameters corresponding to penetration was determined. When the AWP of the weld pool is within a certain range and the values of LWR and ACA are close to their maximum and minimum respectively, the penetration is in good condition. A mathematical model with the weld pool geometry parameters as independent variables and the back-bead width (the indicator of the penetration state) as a dependent variable was established based on multivariable linear regression analysis, and relevant statistical tests were carried out. Multivariable linear regression equations for the weld pool geometry parameters and the back-bead width were deduced according 展开更多
关键词 Welding automation PASSIVE vision sensing WELD POOL GEOMETRY PARAMETERS PENETRATION state Mathematical model
无源散射单元电磁散射特性可控方法综述 预览
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作者 郭杰 殷红成 满良 《系统工程与电子技术》 EI CSCD 北大核心 2019年第4期716-723,共8页
从雷达目标和环境特性的模拟需求出发,对无源散射单元进行了定义及分类,分析了电磁散射特性可控技术的本质特征,介绍了常用的可控方法,并从外形控制技术、材料控制技术、雷达吸波材料技术、频率选择表面技术以及等离子技术5个方面对电... 从雷达目标和环境特性的模拟需求出发,对无源散射单元进行了定义及分类,分析了电磁散射特性可控技术的本质特征,介绍了常用的可控方法,并从外形控制技术、材料控制技术、雷达吸波材料技术、频率选择表面技术以及等离子技术5个方面对电磁散射特性可控方法的国内外现状进行了剖析。结合工程需求,阐述了该领域所面临的问题与挑战,简要展望了发展趋势。 展开更多
关键词 无源 散射单元 电磁散射特性 可控方法 雷达散射截面
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Development status of high power fiber lasers and their coherent beam combination
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作者 Zejin LIU Xiaoxi JIN +2 位作者 Rongtao SU Pengfei MA Pu ZHOU 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第4期52-83,共32页
High-power fiber laser has been emerged great potential in a wide range of applications and becomes a robust candidate for high energy solid state laser system. To further increase the output brightness of single-chan... High-power fiber laser has been emerged great potential in a wide range of applications and becomes a robust candidate for high energy solid state laser system. To further increase the output brightness of single-channel fiber laser, high-brightness pump sources and high-power-handling passive components should be fabricated and utilized in the fiber laser systems, in addition to the advanced techniques for multiple nonlinear effects managements. The state-of-the-art high power fiber lasers are reviewed, in terms of narrow-linewidth fiber lasers, broadband fiber lasers and fiber lasers at 2 μm. Coherent beam combining is a promising technique to obtain higher output power while maintaining excellent beam quality simultaneously,which breaks through the bottlenecks of single-channel fiber laser. Based on a series of key techniques for coherent beam combining, high-power coherent beam combining of fiber lasers could be enabled with high combining efficiency. In this paper, we review the progress of high-power fiber lasers and their coherent beam combining in the recent decade, particularly the relevant work in our group. The future prospects of fiber lasers and coherent beam combining technique are also discussed. 展开更多
关键词 FIBER LASERS and AMPLIFIERS nonlinear effects and mode INSTABILITY COHERENT beam combining PASSIVE components 2μm FIBER LASERS
Study of the Thermal Field Upstream and Downstream of Two Heat Sources Placed in the Turbulent Flow of the Ambient Air Cooled through an Air-Ground Heat Exchanger 预览
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作者 B.S.Tagne-Kaptue Oumarou Hamandjoda +4 位作者 B.Kenmeugne J.Kenfack A.Kanmogne L.Meva’a D.Ndapeu 《能源与动力工程:英文版》 2019年第8期292-311,共20页
In order to more easily highlight the influence of cooled ambient air through an air-ground heat exchanger on the process of diffusion and mixing of heat around an electronic component and a photovoltaic solar module,... In order to more easily highlight the influence of cooled ambient air through an air-ground heat exchanger on the process of diffusion and mixing of heat around an electronic component and a photovoltaic solar module, we undertook to study the thermal field beforehand. The turbulent model has applied a realizable k-ε two equations model and the two-dimensional Reynolds Averaged Navier-Stokes (RANS) equations are discretized with the second order upwind scheme. The SIMPLE algorithm, which is developed using control volumes, is adopted as the numerical procedure. Calculations were performed for a wide variation of the Reynolds numbers. Our results reveal, on the one hand, that the use of an air-ground heat exchanger accelerates the dispersion of the thermal field around the PV panel. On the other hand, with increasing Reynolds number, the instabilities appear in the wake zone, showing an oscillatory flow, also called von Karman Vortex Street. Our air-ground heat exchanger has an important influence on the diffusion process of the thermal field. Comparison of numerical results with the experimental data available in the literature is satisfactory. 展开更多
关键词 Passive scalar linear heat source PV module turbulent flow CFD.
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建筑被动式节能设计研究 预览
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作者 王峰 谢海霞 《工程建设与设计》 2019年第1期47-49,共3页
当前,节能型建筑和相关技术已经逐步成为社会各方的关注点,而建筑被动式节能主要是通过气候资源调整来改变人居环境质量。作为一种新型节能方式,其核心就是要依靠相关技术降低建筑能源消耗,通过各种设计方法减少各类设备设施对环境改造... 当前,节能型建筑和相关技术已经逐步成为社会各方的关注点,而建筑被动式节能主要是通过气候资源调整来改变人居环境质量。作为一种新型节能方式,其核心就是要依靠相关技术降低建筑能源消耗,通过各种设计方法减少各类设备设施对环境改造产生的影响,同时,达到节能减排的目的。论文结合建筑实例,对建筑被动式节能设计进行研究,介绍了多方面的设计思路,并分析了相应的节能成效,可为其他建筑被动式节能设计提供参考。 展开更多
关键词 建筑 被动式 节能减排 研究设计
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Discussion on the Intelligent Design of Ultra-Low Energy Consumption Passive Buildings 预览
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作者 Xin Tong Xiaolin Yang Xiao Ma 《建筑与工程前沿研究(英文)》 2019年第2期20-24,共5页
With the continuous development of science and technology and the gradual improvement of modem building technology, people pay more and more attention to the introduction of advanced technology in architectural design... With the continuous development of science and technology and the gradual improvement of modem building technology, people pay more and more attention to the introduction of advanced technology in architectural design, such as the application of intelligent technology. With the increasingly severe environmental situation, people are increasingly demanding the environmental performance and green performance of buildings. The establishment of ultra-low energy consumption passive buildings has become one of the key construction contents of construction projects. This paper mainly analyzes the design points and architectural forms of related buildings from the perspective of intelligent control. 展开更多
关键词 Ultra-low energy CONSUMPTION PASSIVE BUILDINGS INTELLIGENT design
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无线无源转速传感特征变换电路设计与研究 预览
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作者 魏晓飞 洪应平 +3 位作者 任乾钰 张会新 王刚 熊继军 《仪表技术与传感器》 CSCD 北大核心 2019年第6期72-76,90共6页
针对特殊环境下高速转速无线传感特征信号提取的需求,设计了基于数字频率合成器、检波器的高速解调电路结构,实现了基于单音频率的无线无源转速传感特征信号拾取。设计了一种单音频率信号源,可以实现高达600MHz的稳定信号输出。基于所... 针对特殊环境下高速转速无线传感特征信号提取的需求,设计了基于数字频率合成器、检波器的高速解调电路结构,实现了基于单音频率的无线无源转速传感特征信号拾取。设计了一种单音频率信号源,可以实现高达600MHz的稳定信号输出。基于所设计的单音高速变换电路构建转速测试平台系统,通过无线无源方法实现高速转速参数的提取,实验验证了该无线无源转速传感测试系统可以实现转速参数高速获取且具有无需引线、无需供电的特点,可以用来实现工程化传感器的小型化以及集成化应用。 展开更多
关键词 单音频率 包络检波器 转速 无线 无源 解调电路
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Determining the IgG concentrations in bovine colostrum and calf sera with a novel enzymatic assay 预览
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作者 M.Drikic C.Windeyer +3 位作者 S.Olsen Y.Fu L.Doepel J.De Buck 《畜牧与生物技术杂志:英文版》 SCIE CAS CSCD 2019年第1期239-247,共9页
Background: Immune protection in newborn calves relies on a combination of the timing,volume and quality of colostrum consumed by the calf after birth.Poor quality colostrum with inadequate immunoglobulin concentratio... Background: Immune protection in newborn calves relies on a combination of the timing,volume and quality of colostrum consumed by the calf after birth.Poor quality colostrum with inadequate immunoglobulin concentration contributes to failed transfer of passive immunity in calves,leading to higher calf morbidity and mortality.Therefore,estimating colostrum quality and ensuring the transfer of passive immunity on farm is of critical importance.Currently,there are no on-farm tools that directly measure immunoglobulin content in colostrum or serum.The aim of this study was to apply a novel molecular assay,split trehalase immunoglobulin G assay(STIGA),to directly estimate immunoglobulin content in dairy and beef colostrum and calf sera,and to examine its potential to be developed as on-farm test.The STIGA is based on a split version of trehalase TreA,an enzyme that converts trehalose into glucose,enabling the use of a common glucometer for signal detection.In a first study,60 dairy and64 beef colostrum and 83 dairy and 84 beef calf sera samples were tested with STIGA,and the resulting glucose production was measured and compared with radial immunodiffusion,the standard method for measuring immunoglobulin concentrations.Results: Pearson correlation coefficients between the methods were determined and the sensitivity,specificity,and accuracy of the test were calculated for different colostrum quality and failed transfer of passive immunity cut-off points.The correlations of the STIGA measured by colorimetric enzymatic reaction compared to radial immunodiffusion for dairy and beef colostrum were 0.72 and 0.73,respectively,whereas the correlations for dairy and beef sera were 0.9 and 0.85,respectively.Next,STIGA was tested in a blinded study with fresh colostrum and serum samples where the correlation coefficient was 0.93 and 0.94,respectively.Furthermore,the performance of STIGA followed by glucometer readings resulted in correlations with radial immunodiffusion of 0.7 and 0.85 for dairy and beef colostrum and 0.94 and 0 展开更多
关键词 CATTLE COLOSTRUM IMMUNOGLOBULINS Passive immunity Radial immunodiffusion Split TREHALASE
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