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向心分离采样器级常数的估算 被引量:1
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作者 卢正永 《辐射防护》 CAS CSCD 北大核心 1990年第3期223-228,共6页
在设计向心分离采样器时,需估算其各收集级的级常数D_(ae)(50)值,但目前尚无现成的计算公式可用。本文对多种型号的向心分离采样器的结构参数与实验刻度结果进行了对比分析,在撞击器计算公式的基础上,给出了一个修正公式,用于估算向心... 在设计向心分离采样器时,需估算其各收集级的级常数D_(ae)(50)值,但目前尚无现成的计算公式可用。本文对多种型号的向心分离采样器的结构参数与实验刻度结果进行了对比分析,在撞击器计算公式的基础上,给出了一个修正公式,用于估算向心分离采样器的级常数,结果与实验值基本一致,可供设计向心分离器时作参考。 展开更多
关键词 向心分离采样 级常数D_(a)(50) 估算 修正公式
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氡子体粒度分离采样器研制
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作者 李惠彬 韩斌 +1 位作者 高洪恩 李国申 《核电子学与探测技术》 CAS CSCD 北大核心 2014年第1期1-4,50,共5页
根据氡子体与人工放射性气溶胶粒径的差异,研制了一套氡子体粒度分离采样器。这种装置能在采样过程中分离掉氡子体,主要采集关注的人工放射性气溶胶。使用这种采样器进行采样,可显著降低氡子体的干扰,提高监测灵敏度。该采样器经过改造... 根据氡子体与人工放射性气溶胶粒径的差异,研制了一套氡子体粒度分离采样器。这种装置能在采样过程中分离掉氡子体,主要采集关注的人工放射性气溶胶。使用这种采样器进行采样,可显著降低氡子体的干扰,提高监测灵敏度。该采样器经过改造,也可用于放射性气溶胶连续监测仪。 展开更多
关键词 人工放射性气溶胶 氡子体粒度分离采样 灵敏度
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ISO15189认可过程中两种分离胶采样管的质量评价
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作者 吴洪坤 李畅 +1 位作者 仲人前 周琳 《国际检验医学杂志》 CAS 2016年第4期463-464,467,共3页
目的探讨建立两种不同的分离胶采样管的质量评价方法。方法以硅化玻璃采血管为标准管,以两种分离胶采样管为测试管,随机收集50例患者血清,利用电化学发光、酶联免疫吸附法、反射发光法、免疫荧光法等方法定量或者定性检测血清中各种临... 目的探讨建立两种不同的分离胶采样管的质量评价方法。方法以硅化玻璃采血管为标准管,以两种分离胶采样管为测试管,随机收集50例患者血清,利用电化学发光、酶联免疫吸附法、反射发光法、免疫荧光法等方法定量或者定性检测血清中各种临床免疫、临床生化指标,并进行相应的统计分析。结果对于定量项目而言,两种分离胶采样管与标准管相比,检测结果比较差异无统计学意义(P>0.05);对于定性项目而言,两种分离胶采样管与标准管相比,真阳性率和真阴性率比较差异无统计学意义(P>0.05,K>0.75),一致性较好。结论通过使用不同的检测方法和检测项目证明了分别采用两种分离胶采样管不会影响到检测结果的准确性和一致性,初步建立了ISO15189实验室认可过程中该实验室针对外部供应品的质量评价方法。 展开更多
关键词 分离采样 检验前过程 外部供应品
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CCD 结构的离散性对成象质量的影响 被引量:1
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作者 仲思东 郑琳 《计量学报》 CSCD 北大核心 1998年第1期28-34,共7页
本文提出用调制传递函数MTF评价电荷耦合器件CCD图象传感器成象质量的方法,给出计算CCD图象传感器MTF的公式,并着重分析讨论了CCD图象传感器的离散性对成象质量的影响,为精确进行CCD及其它离散器件的系统设计提供... 本文提出用调制传递函数MTF评价电荷耦合器件CCD图象传感器成象质量的方法,给出计算CCD图象传感器MTF的公式,并着重分析讨论了CCD图象传感器的离散性对成象质量的影响,为精确进行CCD及其它离散器件的系统设计提供了理论依据。 展开更多
关键词 电荷耦合器件 调制传递函数 分离采样
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YC—1型自动岩屑采集机的开发与应用 被引量:3
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作者 石怀荣 《石油机械》 北大核心 2001年第4期34-35,1,共2页
新研制的YC— 1型自动岩屑采集机主要由采样分离机构、清洗机构和烘干装盒机构组成。它有 3个显著特点 :( 1 )采样分离机构采用振动方式 ,振动频率可调 ,适用于不同粘度的钻井液 ,能除掉大块假样。 ( 2 )工作过程以时间为控制基准 ,每... 新研制的YC— 1型自动岩屑采集机主要由采样分离机构、清洗机构和烘干装盒机构组成。它有 3个显著特点 :( 1 )采样分离机构采用振动方式 ,振动频率可调 ,适用于不同粘度的钻井液 ,能除掉大块假样。 ( 2 )工作过程以时间为控制基准 ,每一步骤的完成有一定的时间间隔 ,且根据各油井的钻井速度及取样时间的不同 ,整体可调。设计了自动和手动两套控制程序 ,各部分机构均可独立工作 ,可单独进行清洗或烘干。 ( 3)微机遥控系统可有效地控制机械部分的运动 ,若有钻时仪 ,可以联控 ,实现机电、计算机合一随钻录取资料的目标。 展开更多
关键词 YC-1型 岩屑采集机 随钻采集功能 震动分离 结构特点 采样分离机构
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Blind Separation of Speech Signals Based on Wavelet Transform and Independent Component Analysis 被引量:4
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作者 吴晓 何静菁 +2 位作者 靳世久 徐安桃 王伟魁 《Transactions of Tianjin University》 EI CAS 2010年第2期123-128,共6页
Speech signals in frequency domain were separated based on discrete wavelet transform (DWT) and independent component analysis (ICA). First, mixed speech signals were decomposed into different frequency domains by DWT... Speech signals in frequency domain were separated based on discrete wavelet transform (DWT) and independent component analysis (ICA). First, mixed speech signals were decomposed into different frequency domains by DWT and the subbands of speech signals were separated using ICA in each wavelet domain; then, the permutation and scaling problems of frequency domain blind source separation (BSS) were solved by utilizing the correlation between adjacent bins in speech signals; at last, source signals were reconstructed from single branches. Experiments were carried out with 2 sources and 6 microphones using speech signals at sampling rate of 40 kHz. The microphones were aligned with 2 sources in front of them, on the left and right. The separation of one male and one female speeches lasted 2.5 s. It is proved that the new method is better than single ICA method and the signal to noise ratio is improved by 1 dB approximately. 展开更多
关键词 wavelet transform independent component analysis blind source separation
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Occurrence and Antibiotic Susceptibility Profile of Streptococcus spp. Isolated from Ewe's Milk
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作者 Athanasios Alexopoulos Stavros Plessas +3 位作者 Zafiris Abas Vasiliki Lagka Antonis Zdragas Eugenia Bezirtzoglou 《Journal of Food Science and Engineering》 2013年第12期657-661,共5页
The purpose of this study was to determine the occurrence and antimicrobial resistance of Streptococcus spp. isolated from fresh ewe's milk and consequently to draw conclusions concerning the health condition of the ... The purpose of this study was to determine the occurrence and antimicrobial resistance of Streptococcus spp. isolated from fresh ewe's milk and consequently to draw conclusions concerning the health condition of the animal flocks and the current trends of antibiotic use in small ruminants. A total of 77 mountainous sheepfolds were investigated representing 10% of all transhumant sheep and goats flocks in the area. Duplicate milk samples were collected from January to February transferred to the laboratory and analyzed for the presence of Streptococcus spp. by using the serial dilution method and plating on the surface of Slanetz and Bartley agar. The isolates were tested against nine antimicrobial agents with the Kirby-Bauer disk diffusion method. The results showed that Streptococcus spp. occurred in 84.4% of the samples and in counts ranged between 1.8 log CFU/mL and 4.6 log CFU/mL. Concerning susceptibility, only 1.3% of the isolates were resistant to all antimicrobials while 27.3% were fully susceptible. Resistance to cefepime was the most common (93.1%) observation followed by resistance to ampicillin (82.1%), ciprofloxacine (58.3%) and meropenem (51.9%). The isolates were vancomycin susceptible at a rate of 83.6%. Multidrug resistance to at least three antibiotics was observed to be 22.1% of Streptococcus spp.. Given the prevalence of Streptococcus spp. and the elevated resistance of isolates to various antibiotics it is concluded that further examinations and even interventions are required in order to pertain the appropriate animal health and milk quality. 展开更多
关键词 Antibiotic ewe's milk Streptococcus.
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Characterizing Constituents of Sediment Phosphorus Fractionation in a Freshwater Shallow Lake System
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作者 Xiao PU Jing XIE +2 位作者 Hongguang CHENG Shengtian YANG Lu LU 《Agricultural Science & Technology》 CAS 2014年第8期1380-1383,共4页
This study aimed to characterize constituents of phosphorus (P) fractionation as wel as reciprocities among factors in sediments of a freshwater shal ow lake. [Method] Surface sediment was discretely sampled at 24 s... This study aimed to characterize constituents of phosphorus (P) fractionation as wel as reciprocities among factors in sediments of a freshwater shal ow lake. [Method] Surface sediment was discretely sampled at 24 sites through Van Veen grabs. Based on a modified sequential extraction scheme, P fractionation was determined as Fe/Al bound P (Fe/Al-P), Ca bound P (Ca-P), solute and re-ductive P (S/R-P) and organic P (OP). Curve estimation and Pearson product-mo-ment correlation were employed for statistical analysis. [Result] Total P (TP) content ranged from 443 to 774 mg/kg. Inorganic P (IP) was the major component of TP, of which Ca-P was dominated with an average of 51%±9.7%. Average contents of P fractionation were in the fol owing order: Ca-P(51%) 〉 OP(29%) 〉 S/R-P(8%) 〉Fe/Al-P(7%). The molar ratio of Fe to P was 11 - 20, close to the threshold value of P leaching. [Conclusion] In freshwater shal ow lakes, IP and Ca-P were prone to be relatively high, whereas Fe/Al-P was low compared with deep lakes. Occurrence of spatial y monotonic gradient indicated the primary causation of anthropogenic sources. Imminent sediment P liberation was also expected. Close associations a-mong TP, Fe/Al-P and Ca-P, implying that anthropogenic P was mainly bound to metals in particulates. Significant correlations of TOC and P fractionation highlighted endogenous mechanism and authigenic origin in sediments. 展开更多
关键词 Phosphorus fractionation constituent characterization Surface sediment Freshwater shallow lake
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