期刊文献+
共找到2,121篇文章
< 1 2 107 >
每页显示 20 50 100
Rock mass response for lined rock caverns subjected to high internal gas pressure 被引量:3
1
作者 Davi Rodrigues Damasceno Johan Spross Fredrik Johansson 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第1期119-129,共11页
The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass ... The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur.Analytical and numerical models can be used to estimate the rock mass response to high internal pressure;however,the fitness of these models under different in situ stress conditions and cavern shapes has not been studied.In this paper,the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied.The analytical model is derived in detail and finite element(FE)models considering both two-dimensional(2D)and three-dimensional(3D)geometries are presented.These models are verified with field measurements from the LRC in Skallen,southwestern Sweden.The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights.For the case of anisotropic horizontal in situ stresses,as the conditions in Skallen,the 3D FE model is the best approach. 展开更多
关键词 lined rock caverns(LRCs) High pressure Rock mass response In situ stress condition Cavern shape Gas storage
下载PDF
Methods for the Determination of Stable Isotopes of Carbon and Nitrogen Directly in Valine, Proline, Glutamine, and Glutamic Acid
2
作者 Lamzira Farulava Levani Eliashvili +1 位作者 Vakhtang Betlemidze Bachana Sulava 《American Journal of Analytical Chemistry》 2023年第10期467-480,共14页
Amino acids are very important compounds for the body and are involved in important functions that keep us healthy. Amino acids are essential components such as valine, proline, glutamine and glutamic acid. They can b... Amino acids are very important compounds for the body and are involved in important functions that keep us healthy. Amino acids are essential components such as valine, proline, glutamine and glutamic acid. They can be synthesized either naturally or artificially. To examine the metabolism and regulate the synthesis process, compounds labeled with nitrogen or carbon isotopes need to be used. These isotopic compounds allow for more extensive research and enable studies that would otherwise be impossible. However, their use is dependent on the availability of simple, efficient methods for isotopic analysis. Currently, the determination of the atomic fraction of carbon and nitrogen isotopes is only possible through their conversion into molecular nitrogen or carbon monoxide or carbon dioxide. This leads to the loss of information about isotopic enrichment in specific centers of the molecule. This article explores a new direct approach to determining the atomic fraction of carbon and nitrogen isotopes in the isotope-modified or identical centers of these compounds. This method eliminates the transfer process and dilution due to nitrogen and carbon impurities. It is now possible to simultaneously determine the atomic fraction of nitrogen and carbon isotopes in the research substance. This method can be applied to amino acids, making it an effective tool for proposing new research methods. Several articles [1] [2] [3] have proposed similar methods for organic compounds and amino acids. 展开更多
关键词 VAline PROline GLUTAMINE Glutamic Acid mass Spectrometer mass Spectrum Ion Current INTENSITY mass lines Molecular and Fragment Ions
下载PDF
Genetic Variation Assessed with Microsatellites in Mass Selection Lines of the Pacific Oyster (Crassostrea gigas) in China 被引量:2
3
作者 WANG Xubo LI Qi +1 位作者 YU Hong KONG Lingfeng 《Journal of Ocean University of China》 SCIE CAS 2016年第6期1039-1045,共7页
Abstract Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding pro- grams in China were examined at ten polymorphic microsatellite loci to assess the lev... Abstract Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding pro- grams in China were examined at ten polymorphic microsatellite loci to assess the level of allelic diversity and estimate the effective population size. These data were compared with those of their base population. The results showed that the genetic variation of the four generations were maintained at high levels with an average allelic richness of 18.8-20.6, and a mean expected heterozygosity of 0.902-0.921. They were not reduced compared with those of their base population. Estimated effective population sizes based on temporal variances in microsatellite frequencies were smaller to that of sex ratio-corrected broodstock count estimates. Using a rela- tively large number ofbroodstock and keeping an equal sex ratio in the broodstock each generation may have contributed to retaining the original genetic diversity and maintaining relatively large effective population size. The results obtained in this study showed that the genetic variation was not affected greatly by mass selection progress and high genetic variation still existed in the mass selection lines, suggesting that there is still potential for increasing the gains in future generations of C. gigas. The present study provided im- portant information for future genetic improvement by selective breeding, and for the design of suitable management guidelines for genetic breeding of C. gigas. 展开更多
关键词 Pacific oyster genetic variation MICROSATELLITE mass selection line effective population size
下载PDF
Reconstructed annual glacier surface mass balance in theányêmaqên Mountains,Yellow River source,based on snow line altitude 被引量:1
4
作者 LI Kai-ji CAO Bo +2 位作者 GUAN Wei-jin PAN Bao-tian SHANGGUAN Dong-hui 《Journal of Mountain Science》 SCIE CSCD 2022年第4期1070-1081,共12页
Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources.In this study,we analyzed the changes in glacier area,snow line altitude(SLA)and surface elevation in theány... Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources.In this study,we analyzed the changes in glacier area,snow line altitude(SLA)and surface elevation in theányêmaqên Mountain region using multisource remote sensing data.Then,the annual mass balance of two glaciers was reconstructed by using SLA-mass-balance gradient method.The results showed that the glacier area in theányêmaqên Mountains decreased by 29.4 km2from 1985 to 2017.The average SLAs of the Halong Glacier and Yehelong Glacier were approximately 5290 m and 5188 m,respectively.The glacier mass balance for the two glaciers from 1990 to 2020 was-0.71 m w.e.a^(-1) and-0.63 m w.e.a^(-1),respectively.Our results indicate that SLA is an important indicator of glacier changes,and a long sequence of SLAs can more accurately reconstruct the glacier mass balance of the glacier.The mean annual glacial meltwater-fed streamflow is 1.45×10^(7)m^(3) and 1.12×10^(7)m^(3),respectively.Sensitivity analysis indicates that summer air temperature plays a leading role in regard to the influential climatic factors of glacial retreat in theányêmaqên Mountains.This highlights the potential of the methodology for application on reconstructing annual glacier surface mass balance at larger scales without direct measurements. 展开更多
关键词 Snow line altitude(SLA) Glacier annual mass balance reconstruction Glacier changes ányêmaqên Mountains
下载PDF
Use of a TG-Bridge/Mass Spectrometry Method for On-line Monitoring the Emissions of Pine Needles Combustion
5
作者 M. Statheropoulos N. Tzamtzis +2 位作者 A. Pappa S. Karma Naian Liu 《火灾科学》 CSCD 2004年第3期135-144,共10页
森林火灾排放物主要包含气体、挥发性有机化合物(VOCs)、和半挥发性有机化合物(SVOCs),这些物质会严重威胁消防队员和居民的健康。森林火灾烟气是一种包含固体颗粒、液体和气体化合物的复杂混合物。在火前锋附近(靠近消防队员)或者离火... 森林火灾排放物主要包含气体、挥发性有机化合物(VOCs)、和半挥发性有机化合物(SVOCs),这些物质会严重威胁消防队员和居民的健康。森林火灾烟气是一种包含固体颗粒、液体和气体化合物的复杂混合物。在火前锋附近(靠近消防队员)或者离火前锋很远(但靠近居民)的地方,当苯、甲苯、烯烃等有机化合物的浓度超过各健康安全组织规定的极限值,就可能对健康产生影响。本文给出了一种使用室内热重桥 质谱联用对炉内松针燃烧实验进行火前锋排放物在线监测的新方法。该燃烧实验被认为含氧量较低,这是真实森林火灾中通常的情形。使用这种方法测量得到的苯和甲苯的最大浓度分别是1050和2050ppm。CO2的最大浓度超过10.000ppm。 展开更多
关键词 松针燃烧排放物 热重桥/质谱监测方法 挥发性有机化合物 VOCs 森林火灾 大气检测技术
下载PDF
Dynamic mass variation and multiphase interaction among steel, slag, lining refractory and nonmetallic inclusions: Laboratory experiments and mathematical prediction 被引量:6
6
作者 Ju-jin Wang Li-feng Zhang +2 位作者 Gong Cheng Qiang Ren Ying Ren 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2021年第8期1298-1308,共11页
The mass transfer among the multiphase interactions among the steel, slag, lining refractory, and nonmetallic inclusions during the refining process of a bearing steel was studied using laboratory experiments and nume... The mass transfer among the multiphase interactions among the steel, slag, lining refractory, and nonmetallic inclusions during the refining process of a bearing steel was studied using laboratory experiments and numerical kinetic prediction. Experiments on the system with and without the slag phase were carried out to evaluate the influence of the refractory and the slag on the mass transfer. A mathematical model coupled the ion and molecule coexistence theory, coupled-reaction model, and the surface renewal theory was established to predict the dynamic mass transfer and composition transformation of the steel, the slag, and nonmetallic inclusions in the steel. During the refining process,Al_(2)O_(3) inclusions transformed into Mg O inclusions owing to the mass transfer of [Mg] at the steel/refractory interface and(Mg O) at the slag/refractory interface. Most of the aluminum involved in the transport entered the slag and a small part of the aluminum transferred to lining refractory, forming the Al_(2)O_(3) or Mg O·Al_(2)O_(3). The slag had a significant acceleration effect on the mass transfer. The mass transfer rate(or the reaction rate) of the system with the slag was approximately 5 times larger than that of the system without the slag. In the first 20 min of the refining, rates of magnesium mass transfer at the steel/inclusion interface, steel/refractory interface, and steel/slag interface were x, 1.1 x, and 2.2 x,respectively. The composition transformation of inclusions and the mass transfer of magnesium and aluminum in the steel were predicted with an acceptable accuracy using the established kinetic model. 展开更多
关键词 mass transfer STEEL SLAG lining refractory nonmetallic inclusions kinetic model
下载PDF
Mass Selection for Growth Improvement in Black Shell Line of Pacific Oyster Crassostrea gigas 被引量:2
7
作者 XU Chengxun LI Qi +2 位作者 CHONG Jindou LIU Shikai KONG Lingfeng 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第6期1411-1416,共6页
The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a s... The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a selective breeding program on both shell color and growth rate of C.gigas since 2010.A black shell line was obtained through four-generation family selection.In this study,mass selection for growth improvement was conducted in the sixth generation and seventh generation of black shell lines.To assess the progress of potential genetic improvement,the progeny of two generations of black shell lines were selected to evaluate their shell heights via a 450-day farming experiment.As the results,after growing for 450 days,the sixth generation and seventh generation of selected lines were 9.03% and 11.42% larger than the control lines,respectively.During the grow-out stage,the genetic gain of two generations was 8.82%±0.18% and 11.54%±0.43%,respectively;and the corresponding realized heritability was 0.45±0.04 and 0.41±0.04,respectively.These results indicated that the mass selection for shell height achieved steady progress in the two generations of C.gigas. 展开更多
关键词 Pacific OYSTER CRASSOSTREA GIGAS mass selection black shell line genetic gain realized HERITABILITY
下载PDF
The processes and characteristics of mass balance on the Urumqi Glacier No. 1 during 1958-2009 被引量:2
8
作者 WenBin Wang ZhongQin Li +1 位作者 GuoFei Zhang XuLiang Li 《Research in Cold and Arid Regions》 2012年第6期505-513,共9页
As a solid reservoir, a glacier can regulate regional water resources. The annual net mass balance directly reflects the fluctuation of the glacier and climate variability. Based on 51 years of mass balance observatio... As a solid reservoir, a glacier can regulate regional water resources. The annual net mass balance directly reflects the fluctuation of the glacier and climate variability. Based on 51 years of mass balance observation data, the mass balance of Tianshan Mountains Urumqi Glacier No. 1 experienced a nine times positive balance fluctuation and nine times negative balance fluctuation. There were 35 and 16 negative and positive balance years, respectively. From 1996/97 to 2008/09, 12 consecutive negative balance years were observed at Tianshan Mountains Urumqi Glacier No. 1. These results demon- strate that the Urumqi Glacier No. 1 is experiencing a strong negative balance, and the strongest negative balance, -931 mm w.e. (mm water equivalent), during the observation period occurred in 2008. In addition, the cumulative mass balance reached 13,709 mm w.e. in 2008. However, in 2009, the mass balance was positive at 63 mm w.e. The equilibrium-line al- titude changes with the fluctuation in the mass balance, and the effective mass balance gradient is 7.4 mrn/m. In this paper, the headwaters of the Urumqi River were analyzed using meteorological data from 1958 to 2009, including the average seasonal temperature and precipitation. The results showed that the main factor associated with the mass balance variation of Glacier No. 1 is the fluctuation in the summer air temperature, followed by changes in the precipitation. 展开更多
关键词 Urumqi Glacier No. 1 mass balance equilibrium line Tianshan Mountains
下载PDF
Identification of proteins of human colorectal carcinoma cell line SW480 by two-dimensional electrophoresis and MALDI-TOF mass spectrometry 被引量:1
9
作者 Ying-Tao Zhang Yi-Ping Geng +3 位作者 Le Zhou Bao-Chang Lai Lv-Sheng Si Yi-Li Wang 《World Journal of Gastroenterology》 SCIE CAS CSCD 2005年第30期4679-4684,共6页
AIM: To conduct bhe proteomic analysis of human colorectal carcinoma cell line, SW480 by using two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption /ionization-time of flight mass spectromet... AIM: To conduct bhe proteomic analysis of human colorectal carcinoma cell line, SW480 by using two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption /ionization-time of flight mass spectrometry (MALDITOFMS). METHODS: The total proteins of human colorectal carcinoma cell line, SW480 were separated with 2-DE by using immobilized pH gradient strips and visualized by staining with silver nitrate. The gel images were acquired by scanner and 2-DE analysis software, Image Master 2D Elite. Nineteen distinct protein spots were excised from gel randomly and digested in gel by TPCK-trypsin. Mass analysis of the byptic digest peptides mixture was performed by using MALDI-TOF MS. Peptide mass fingerprints (PMFs) obtained by the MALDI-TOF analysis were used to search NCBI, SWISS-PROT and MSDB databases by using Mascot software. RESULTS: PMF maps of all spots were obtained by MALDI-TOF MS and thirteen proteins were preliminarily identified. CONCLUSION: The methods of analysis and identification of protein spots of tumor cells in 2-DE gel with silver staining by MALDI-TOF MS derived PMF have been established. Protein expression profile of SW480 has been obtained. It is demonstrated that a combination of proteomics and cell culture is a useful approach to comprehend the process of colon carcinogenesis. 展开更多
关键词 Colorectal carcinoma SW480 cell line Twodimensional electrophoresis MALDI-TOF MS Peptide mass fingerprinting
下载PDF
Dynamic Response Analysis of the Equivalent Water Depth Truncated Point of the Catenary Mooring Line 被引量:3
10
作者 ZHANG Huo-ming KONG Ling-bin +2 位作者 GUAN Wei-bing HUANG Sai-hua FANG Gui-sheng 《China Ocean Engineering》 SCIE EI CSCD 2017年第1期37-47,共11页
The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedba... The real-time computer-controlled actuators are used to connect the truncated parts of moorings and risers in the active hybrid model testing system. This must be able to work in model-scale real time, based on feedback input from the floater motions. Thus, mooring line dynamics and damping effects are artificially simulated in real time, based on a computer-based model of the problem. In consideration of the nonlinear characteristics of the sea platform catenary mooring line, the equations of the mooring line motion are formulated by using the lumped-mass method and the dynamic response of several points on the mooring line is investigated by the time and frequency domain analysis method. The dynamic response of the representative point on the mooring line is analyzed under the condition of two different corresponding upper endpoint movements namely sine wave excitation and random wave excitation. The corresponding laws of the dynamic response between the equivalent water depth truncated points at different locations and the upper endpoint are obtained, which can provide technical support for further study of the active hybrid model test. 展开更多
关键词 mooting line truncated point dynamic response lumped-mass method time domain simulation
下载PDF
An investigation on changes in glacier mass balance and hypsometry for a small mountainous glacier in the northeastern Tibetan Plateau 被引量:2
11
作者 CAO Bo PAN Bao-tian +1 位作者 CAI Ming-yong WANG Jie 《Journal of Mountain Science》 SCIE CSCD 2017年第8期1624-1632,共9页
Mass balance is a key indicator of the sensitivity of glaciers to climate change. Field measurement is one of the most important ways to study the mass balance of glaciers. Based on observations of mass balance in the... Mass balance is a key indicator of the sensitivity of glaciers to climate change. Field measurement is one of the most important ways to study the mass balance of glaciers. Based on observations of mass balance in the ablation zone of Shuiguan Glacier No.4, Qilian Mountains, China, combined with the balance ratio between accumulation and ablation, we established a linear relation between mass balance and altitude. The results show that the mean annual mass balance of this glacier was ~510 mm w.e. from 2010 to 2013. The uncertainty in the balance ratio value does not lead to a significant difference in the mass balance. The equilibrium-line altitude rose by 180 m from 1972 to 2013, while the accumulation–area ratio decreased from 0.68 to 0.25. These variations may be caused by changes in air temperature. Meanwhile, the glacier is at present not in a steady state, and it may continue to shrink by a further ~900 m, even without further climate warming. In the western Lenglongling Mountains, assuming that the glaciers are in a steady state and the Equilibrium-line altitudes(ELAs)remain similar, there will be only 46 glaciers left, covering a total area of 19.2 km^2, in other words, only 22.3% of the glaciers area in 1972. 展开更多
关键词 Accumulation-area ratio (AAR) Equilibrium-line altitude (ELA) GLACIER mass balance
下载PDF
Minimizing Makespan on Mixed Mass Production Lines of Two and Three Machines 被引量:1
12
作者 B. Guo Y. Nonaka Department of Industrial Management and Engineering, Science University of Tokyo 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162, Japan guo@ms.kagu.sut.ac.jp 《International Journal of Plant Engineering and Management》 1998年第3期11-16,共6页
The objective of the research discussed in this paper has been to find an optimal schedule on mixed mass production lines of two and three machines. Johnson's rule on flow shops is generalized to mixed mass produ... The objective of the research discussed in this paper has been to find an optimal schedule on mixed mass production lines of two and three machines. Johnson's rule on flow shops is generalized to mixed mass production lines. Scheduling methods on three-machine lines are proposed for six special kinds of data of processing times of jobs. The scheduling method on two-machine lines is also proposed. 展开更多
关键词 Scheduling MAKESPAN Mixed mass production line
下载PDF
MODEL OF OPERATING AND BALANCING ASSEMBLY LINE IN A MASS CUSTOMIZATION ENVIRONMENT
13
作者 WeiDong JinYe +1 位作者 WangRong WangZheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2003年第4期344-347,共4页
The successful implementation of mass customization lies on reengineeringtechnology and management methods to organize the production. Especially in assembly phase, variousproduct configurations, due-time penalties an... The successful implementation of mass customization lies on reengineeringtechnology and management methods to organize the production. Especially in assembly phase, variousproduct configurations, due-time penalties and order-driven strategy challenge the traditionaloperation and management of assembly lines. The business features and the operation pattern ofassembly line based on mass customization are analyzed. And the research emphatically studiesvarious technologic factors to improve customer satisfaction and their corresponding implementmethods in operating assembly line. In addition, the models are proposed for operating assembly lineunder dynamic process environment in mass customization. A genetic approach is developed to providethe optimal solution to the models. The effectiveness of the proposed approach is evaluated with anindustrial application. 展开更多
关键词 mass customization Assembly line Balancing Optimal model
下载PDF
Axial Vibration Analysis of the Mud Recovery Line on Deepwater Riserless Mud Recovery Drilling System
14
作者 王国栋 陈国明 +1 位作者 许亮斌 殷志明 《China Ocean Engineering》 SCIE EI CSCD 2014年第3期381-390,共10页
The series connection of multistage pumping module is the common concept of deepwater riserless mud recovery drilling system. In this system, the influence of the mass of pumping module on the vibration of mud recover... The series connection of multistage pumping module is the common concept of deepwater riserless mud recovery drilling system. In this system, the influence of the mass of pumping module on the vibration of mud recovery line cannot be ignored, and the lumped mass method has been utilized to discretize the mud recovery line. Based on the analysis of different boundary conditions, the paper establishes the axial forced vibration model of the mud recovery line considering the seawater damping, and the vibration model analysis provides the universal solution to the vibration model. An example of the two-stage pumping system has been used to analyze the dynamic response of mud recovery line under different excited frequencies. This paper has the important directive significance for the application of riserless mud recovery drilling technology in deepwater surface drilling. 展开更多
关键词 riserless mud recovery drilling lumped mass method mud recovery line axial vibration analysis
下载PDF
OFF-LINE TWO-DIMENSIONAL GAS CHROMATOGRAPHY-MASS SPECTROMETRY FOR ANALYSIS OF ASSENTAL OIL OF MEDICINAL HERB:USE OF ABSORPTION TRAP AS INTERFACE
15
作者 XueYi MA Hui Ping PAN and YaoZu CHEN (National Laboratory of Applied Organic Chemistry and Department of Chemistry,Lanzhou University, Lanzhou 730000) 《Chinese Chemical Letters》 SCIE CAS CSCD 1994年第1期73-76,共4页
The use of an absorption trap off-line 2-DGC in conjunction with a mass spectrometer greatly improved the separation and identification of minor constituents of a complex mixtures such as a natural essential oil. The ... The use of an absorption trap off-line 2-DGC in conjunction with a mass spectrometer greatly improved the separation and identification of minor constituents of a complex mixtures such as a natural essential oil. The absorption trap device used as an interface of 2-DGC offered the advantage of convenient manipulation. 展开更多
关键词 GAS CHROMATOGRAPHY DIMENSIONAL TWO mass line ABSORPTION
下载PDF
Model of an Atom by Analogy with the Transmission Line
16
作者 Milan Perkovac 《Journal of Modern Physics》 2013年第7期899-903,共5页
Model of an atom by analogy with the transmission line is derived using Maxwell’s equations and Lorentz’ theory of electrons. To be realistic such a model requires that the product of the structural coefficient of L... Model of an atom by analogy with the transmission line is derived using Maxwell’s equations and Lorentz’ theory of electrons. To be realistic such a model requires that the product of the structural coefficient of Lecher’s transmission lines σ and atomic number Z is constant. It was calculated that this electromechanical constant is 8.27756, and we call it structural constant. This constant builds the fine-structure constant 1/α = 137.036, and with permeability μ, permittivity ε and elementary charge e builds Plank’s constant h. This suggests the electromagnetic character of Planck’s constant. The relations of energy, frequency, wavelength and momentum of electromagnetic wave in an atom are also derived. Finally, an equation, similar to Schrodinger’s equation, was derived, with a clear meaning of the wave function, which represents the electric or magnetic field strength of the observed electromagnetic wave. 展开更多
关键词 Lecher Transmission line Lorentz’ theory of ELECTRONS Maxwell’s Equations Model of ATOM PLANCK CONSTANT Structural CONSTANT Transverse mass Wave Equation
下载PDF
Chemical Selectivity of Laser Ion Source for on-Line Mass Separator
17
作者 Zhao, Zhizheng Yang, Yongfeng +1 位作者 Cai, Xicheng Somerville, L.P. 《Chinese journal of nuclear physics》 EI 1997年第1期48-52,共5页
Thulium(Tm)atoms are resonantly ionized in a hot tube by stepwise excitations us-ing three dye lasers pumped by a series of copper vapor pulsed at a 10 kHz rate.The chemicalselectivity of the laser ion source is measu... Thulium(Tm)atoms are resonantly ionized in a hot tube by stepwise excitations us-ing three dye lasers pumped by a series of copper vapor pulsed at a 10 kHz rate.The chemicalselectivity of the laser ion source is measured as a function of temperature of the tubes made ofTa,Nb-Zr and TaC.The chemical selectivity rises from 50 to 10000 with decreasing tube temp-erature and strongly depends on the tube material.A chemical selectivity of about 10000 withhigh efficiencies is obtained with the Nb-Zr and TaC tubes.Such a laser ion source can be usedin on-line mass separator to obtain isobarically pure ion beams. 展开更多
关键词 Laser ION SOURCE Chemical SELECTIVITY ON-line mass SEPARATOR
下载PDF
党群逻辑与基层治理型回应——基于桥镇群众走访的研究
18
作者 陈伟 《天津行政学院学报》 北大核心 2024年第4期22-32,共11页
在提升政府回应性的过程中,以公众满意率为核心指标的行政型回应模式面临着回应性悖论。基于此,桥镇通过群众走访的机制创新,主动回应群众诉求,塑造了一套以政治伦理和政治压力为内核,以干部联组和党委政府统筹为路径的治理型回应模式... 在提升政府回应性的过程中,以公众满意率为核心指标的行政型回应模式面临着回应性悖论。基于此,桥镇通过群众走访的机制创新,主动回应群众诉求,塑造了一套以政治伦理和政治压力为内核,以干部联组和党委政府统筹为路径的治理型回应模式。这一模式的逻辑是,党委政府通过责任包干,激活干部内在的责任—情感动力;赋予干部自主空间,弹性回应群众诉求;借助政治统合和群众动员,重塑群众诉求的公共性和政治性。区别于跨层级的行政型回应模式,治理型回应模式在基层治理场域内完成对群众诉求的识别、分类及回应,具有主动性、整体性、低制度化等特点。在政府回应“弱政治化”的背景下,重拾群众路线对提升基层治理绩效和体制合法性具有重要意义。 展开更多
关键词 政府回应性 行政型回应 治理型回应 群众路线 群众走访
下载PDF
信访:民众诉求表达与社会矛盾化解的重要制度安排
19
作者 陈新 卢志朋 《浙江工商大学学报》 北大核心 2024年第5期15-23,共9页
信访工作是中国共产党群众路线的重要体现,是党治国理政的一项特有制度安排,深嵌于中国国家治理场景中。信访制度发轫于新中国成立初期,历经改革开放后的恢复发展,到新时代党和国家对其的改革重塑,反映出不同历史阶段的时代特征。在实... 信访工作是中国共产党群众路线的重要体现,是党治国理政的一项特有制度安排,深嵌于中国国家治理场景中。信访制度发轫于新中国成立初期,历经改革开放后的恢复发展,到新时代党和国家对其的改革重塑,反映出不同历史阶段的时代特征。在实践过程中,信访制度塑造了中央政府、基层政府与信访民众等多行为主体之间复杂的关系样态,呈现出“政府回应与社会抗争”“群众路线与维稳利器”“维权之举与谋利之术”等行为逻辑。就未来改革和研究议程而言,需从宏观上将信访融入国家治理整体格局中思考,从中观上优化信访制度本身的运行逻辑,从微观上健全和完善信访工作的各项机制。 展开更多
关键词 人民信访 群众路线 社会矛盾 法治化
下载PDF
面向火电厂煤粉尘浓度的预测评估算法的研究
20
作者 王博 商宇航 +1 位作者 姚立超 蒋永清 《安全与环境学报》 CAS CSCD 北大核心 2024年第5期1768-1777,共10页
火力发电的主要能源来自煤炭,而由于燃煤发电过程中产生的煤尘扩散是引起火电厂粉尘爆炸风险和尘肺职业病的主要根源之一,因此必须进行实时有效的检测和控制。当前粉尘检测方法仅使用单一的粉尘质量浓度指标来评估粉尘污染整体状况,缺... 火力发电的主要能源来自煤炭,而由于燃煤发电过程中产生的煤尘扩散是引起火电厂粉尘爆炸风险和尘肺职业病的主要根源之一,因此必须进行实时有效的检测和控制。当前粉尘检测方法仅使用单一的粉尘质量浓度指标来评估粉尘污染整体状况,缺乏对多种复合因素影响的考量,依靠单一阈值设定进行报警,易出现误报、漏报等现象,以及忽略粉尘爆炸这一重要事故场景,不能建立粉尘污染全面客观的评价方法。研究建立了一种粉尘质量浓度预测模型,基于金豺优化算法对极限学习机的最优初始权重进行寻优,再使用极限学习机对样本数据进行训练学习,提高神经网络模型的精度,可较为准确地预测30 min以内任意时间间隔的粉尘质量浓度,并将现场数据及模拟仿真数据与建立的粉尘质量浓度预测模型进行对比分析。结果显示:建立的粉尘质量浓度预测模型准确度良好,与现场数据及模拟仿真数据对比误差分别为0.72%和2.1%,可加强对火电厂粉尘环境进行预测预警,从而及时采取合理的粉尘控制策略,确保火电厂的生产安全并降低粉尘对作业人员的职业危害。 展开更多
关键词 安全工程 粉尘防爆 粉尘危害 粉尘质量浓度在线检测 工厂环境 劳动者安全 危险预知
下载PDF
上一页 1 2 107 下一页 到第
使用帮助 返回顶部