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万夏的《本质》:文化的连拱廊与跨界的赝品反讽
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作者 余夏云 《南京师范大学文学院学报》 CSSCI 北大核心 2018年第3期113-120,共8页
作为80年代后半的创作,万夏的《本质》一诗,以生命为主题,呈现了时代变动多音的特质。表面上,诗歌虽极力回避朦胧诗式的大写声调,采用个人化的表述,但其游移不定、自我否定的中年特征,却又恰好暴露了全知的启蒙视角并未退场,且还吊诡地... 作为80年代后半的创作,万夏的《本质》一诗,以生命为主题,呈现了时代变动多音的特质。表面上,诗歌虽极力回避朦胧诗式的大写声调,采用个人化的表述,但其游移不定、自我否定的中年特征,却又恰好暴露了全知的启蒙视角并未退场,且还吊诡地融入了传统文人感伤逸乐的传统。这种背反式的存在,在贾樟柯的《二十四城记》中,得到了强化。翟永明对诗歌极度煽情的改写,揭示了全球化语境下,文化不伦不类的赝品处境,点明《本质》的跨界实践具有批评反讽的功能。 展开更多
关键词 万夏 《本质》 赝品反讽
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回到原点的哲学之思——《本质主义、反本质主义与中国教育学研究》批判 被引量:5
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作者 张荣伟 《当代教育论坛(宏观教育研究)》 2005年第04S期21-28,共8页
《本质主义、反本质主义与中国教育学研究》一文在考察所谓的“本质主义”以及相关的教育学研究的过程中走错了方向,因而在“截取”了所谓的“反本质主义”的一系列时髦话语的同时,也“背负”了其固有的“反本体论”、“反形而上学”的... 《本质主义、反本质主义与中国教育学研究》一文在考察所谓的“本质主义”以及相关的教育学研究的过程中走错了方向,因而在“截取”了所谓的“反本质主义”的一系列时髦话语的同时,也“背负”了其固有的“反本体论”、“反形而上学”的一系列通病。所谓的“本质主义”及其“严重的历史性后果”是“反本质主义”所赋予和强加的。21世纪的中国教育学研究必须深刻地批判和彻底地抛弃所谓的“反本质主义知识观和认识论路线”,坚持马克思主义哲学的一般世界观或本体论的基本观点,否则的话,势必误导现实的教育学研究并进而带来一系列的负面影响。 展开更多
关键词 《本质主义、反本质主义与中国教育学研究》 教育学研究 本体论 评价标准
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从《本质》到《内省》——读琪雅的艺术
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作者 张广军 《美术向导》 2013年第1期44-48,共5页
2011年,在上海美术馆举办的《本质》艺术展吸引了众多的参观者。这是一位来自摩洛哥王国的女艺术家法蒂亚·塔希里(FathiyaTahiri),中文名字琪雅的个人作品展。琪雅从女性的视角创造出很多充满色彩与情感的雕塑和绘画作品。她... 2011年,在上海美术馆举办的《本质》艺术展吸引了众多的参观者。这是一位来自摩洛哥王国的女艺术家法蒂亚·塔希里(FathiyaTahiri),中文名字琪雅的个人作品展。琪雅从女性的视角创造出很多充满色彩与情感的雕塑和绘画作品。她把这次在中国的首次个展命名为《本质》,并告诉观众她的艺术的本质源于内心的感受,而这种感受以想象的方式延伸递进。 展开更多
关键词 琪雅 艺术 《本质》 艺术欣赏
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Rutherford’s Atomic Nucleus versus Landau’s Gigantic Nucleus:Does Nature Favor Flavor Symmetry?
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作者 XU Renxin 《原子核物理评论》 CAS CSCD 北大核心 2024年第3期863-871,共9页
It is hypothesized that,at low temperature,though atomic nuclei are made of 2-flavored nucleons(i.e.,nucleon matter as nuclear droplet),strongly interacting matter(i.e.,gigantic nucleus)with baryon number from A≃10^(3... It is hypothesized that,at low temperature,though atomic nuclei are made of 2-flavored nucleons(i.e.,nucleon matter as nuclear droplet),strongly interacting matter(i.e.,gigantic nucleus)with baryon number from A≃10^(3-9)to-10^(57)would be composed of 3-flavored strangeons if Nature favors always the flavor symmetry of quarks.According to that logic,strangeon matter with A-10^(57)could manifest in the form of pulsar-like compact stars,and multi-messenger observations with advanced facilities(e.g.,China’s FAST)could eventually provide a disproof/proof.It is worth emphasizing that this point of view,based on established“old physics”(i.e.,the standard model of particle physics),may have particular consequences for understanding our material world,for both normal luminous matter and even the dark sector. 展开更多
关键词 dense matter elementary particle symmetry energy neutron star pulsar
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Unveiling the challenges encountered by newly graduated nurses during night shifts:A descriptive qualitative study
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作者 Naomi Kisanuki Miyuki Takase Masako Yamamoto 《International Journal of Nursing Sciences》 CSCD 2024年第4期447-456,共10页
Objectives:Newly graduated nurses commence night shifts during a phase of heightened vulnerability to reality shock,exacerbating the challenges faced by these graduates.Therefore,this study aimed to identify the chall... Objectives:Newly graduated nurses commence night shifts during a phase of heightened vulnerability to reality shock,exacerbating the challenges faced by these graduates.Therefore,this study aimed to identify the challenges experienced by newly graduated nurses when undertaking night shifts in order to help identify a strategy for supporting their adaptation to these shifts.Methods:Semi-structured personal interviews were used to collect data.Fifteen newly graduated nurses were selected to participate in the study by purposive sampling method from November 2021 to March 2022 in one of four general hospitals situated in the southwestern region of Japan.Semi-structured interviews were analyzed by using thematic analysis.Results:The analysis revealedfive central themes and nine subthemes:challenges in task efficiency(task organization challenges,challenges in time-constrained task performance),challenges in responding to patients’changing conditions(challenges in responding to patients’irregular conditions,challenges in responding to nighttime changes in patients’behaviors),challenges in independent practice(challenges in engaging in independent nursing practice,challenges in dealing with unexpected events),challenges in establishing collaborative relationships(challenges in working closely with other staff,challenges in establishing collaborative relationships during night shifts with limited resources),challenges in adapting to shift work(challenges in managing physical conditions for shift work).Conclusions:Newly graduated nurses often encounter challenges in performing their tasks during the transition period.When working night shifts,they face additional hurdles unique to nocturnal duties.Thefindings underscore the necessity for these graduates to develop night shift-specific readiness to effectively navigate the demands inherent in such work schedules. 展开更多
关键词 CHALLENGE Newly graduated nurses Patient care management Qualitative research Shift work schedule Night shifts
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Techno-economic and Environmental Assessments of SAF from Bioamss:An Review
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作者 MAHMOOD T.M.N.Saeed PANG Shusheng CHEN Qiang 《林产化学与工业》 CAS CSCD 北大核心 2024年第5期29-51,共23页
This review presents a comprehensive techno-economic and life-cycle assessment of sustainable aviation fuel(SAF)production from biomass.The critical need for transitioning towards environmentally sustainable alternati... This review presents a comprehensive techno-economic and life-cycle assessment of sustainable aviation fuel(SAF)production from biomass.The critical need for transitioning towards environmentally sustainable alternatives for liquid fuel and aviation industry is first discussed.Key insights encompass the evolutionary progression of biofuel production from first-generation to second-generation biofuels,with a focus on utilizing non-food sources like woody biomass for enhanced sustainability.Available data from the literature on techno-economic assessments of various SAF production pathways are analyzed including production costs,conversion efficiency,and scalability.Moreover,results of lifecycle assessments associated with different SAF production pathways are presented,providing essential insights for decision-making processes.The challenges of scaling up woody biomass-based SAF production are discussed based on the assessment results,and recommendations are proposed to steer stakeholders towards a greener and more sustainable trajectory for aviation operations. 展开更多
关键词 sustainable aviation fuel woody biomass production costs minimum fuel selling price lifecycle assessment greenhouse gas emissions climate change
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Remanufacturing production planning considering quality cost and demand substitution 被引量:2
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作者 苏春 安政 《Journal of Southeast University(English Edition)》 EI CAS 2011年第2期222-226,共5页
Aiming to minimize the total production costs in a single planning period, a nonlinear integer programming model for remanufacturing production plans is established considering the influence of different qualities of ... Aiming to minimize the total production costs in a single planning period, a nonlinear integer programming model for remanufacturing production plans is established considering the influence of different qualities of returns acting on production cost. Three different remanufacturing and discarding strategies are adopted to analyze the change rules of the total production costs. The results returns is greater than indicate that when the number of remanufacturing returns of high the demand, preferentially quality and discarding those of low quality can bring better economic benefits due to manufacturing cost reduction. However, when the number of returns is smaller than the demand, there is no need to consider grading of returns, whereas new demand of remanufacturing. parts are required to satisfy the 展开更多
关键词 REMANUFACTURING production planning qualitycost demand substitution
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Integrated assessment of sea water quality based on BP artificial neural network 被引量:3
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作者 李雪 刘长发 +1 位作者 王磊 邱文静 《Marine Science Bulletin》 CAS 2011年第2期62-71,共10页
In order to carry out an integrated assessment of sea water quality objectively, this paper based on the concept and principle of artificial neural network, generated appropriate training samples for BP artificial neu... In order to carry out an integrated assessment of sea water quality objectively, this paper based on the concept and principle of artificial neural network, generated appropriate training samples for BP artificial neural network model through the method of producing samples to the concentration of various pollution index of sea water quality from the viewpoint of threshold, established the BP artificial neural network model of sea water quality assessment using multi-layer neural network with error back-propagation algorithm. This model was used to assess water environment and obtain sea water quality categories of offshore area in Bohai Bay through calculating. The calculations shown that pollution index in river's wet season was higher than that in dry season from 2004 to 2007, and the pollution was particularly serious in 2005 and 2006, but a little better in 2007. The assessed results of cases shown that the model was reasonable in design and higher in generalization, meanwhile, it was common, objective and practical to sea water quality assessment. 展开更多
关键词 artificial neural network sea water quality training sample connection weight ASSESSMENT
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Neighborhood Union of Essential Sets and Hamiltonicity of Claw-Free Graphs
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作者 徐新萍 《Journal of Southeast University(English Edition)》 EI CAS 2002年第2期184-187,共4页
Let G be a graph, an independent set Y in G is called an essential independent set (or essential set for simplicity), if there is {y 1,y 2} Y such that dist (y 1,y 2)=2. In this paper, we wi... Let G be a graph, an independent set Y in G is called an essential independent set (or essential set for simplicity), if there is {y 1,y 2} Y such that dist (y 1,y 2)=2. In this paper, we will use the technique of the vertex insertion on l connected ( l=k or k+1,k≥2 ) claw free graphs to provide a unified proof for G to be hamiltonian or 1 hamiltonian, the sufficient conditions are expressed by the inequality concerning ∑ki=0N(Y i) and n(Y) for each essential set Y={y 0,y 1,...,y k} of G , where Y i={y i,y i-1 ,...,y i-(b-1) }Y for i∈{0,1,...,k} (the subscriptions of y j ’s will be taken modulo k+1 ), b ( 0【b【k+1 ) is an integer, and n(Y)={v∈V(G): dist (v,Y)≤2 }. 展开更多
关键词 HAMILTONICITY claw free graph neighborhood union vertex insertion essential set
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Composition of Essential Oils of Morus alba Leaves and Chamaecyparis pisifera Outer Heartwood 被引量:1
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作者 刘志明 王海英 +2 位作者 王芳 潘晓星 田补 《Agricultural Science & Technology》 CAS 2010年第8期7-9,共3页
[Objective] The aim was to explore the composition of essential oils of Morus alba leaves and Chamaecyparis pisifera outer heartwood. [Method] The essential oils of M. alba leaves and C. pisifera outer heartwood were ... [Objective] The aim was to explore the composition of essential oils of Morus alba leaves and Chamaecyparis pisifera outer heartwood. [Method] The essential oils of M. alba leaves and C. pisifera outer heartwood were analyzed by gas chromatography-mass spectrometry,respectively. [Result] Alcohols [phytol (59.47%,extracted 3 h for M. alba leaves),α-cadinol (38.77%,extracted 6 h for C. pisifera outer heartwood)] were their first principal volatile components. Phytol was usually used as pharmaceutical raw material and α-cadinol was a kind of active organic compound with antibacterial function. [Conclusion] The essential oils of M. alba leaves and C. pisifera outer heartwood with hydrodistillation have medicinal value. 展开更多
关键词 Morus alba Chamaecyparis pisifera Essential oil Gas chromatography-mass spectrometry
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China's Industrial Upgrade and Human Capital Improvement 被引量:1
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作者 张车伟 高文书 《China Economist》 2016年第4期22-45,共24页
Based on statistics, this paper reviews China's economic growth and industrial upgrade since the reform and opening up in 1978 and estimates the contribution of industrial restructuring to economic growth. With the y... Based on statistics, this paper reviews China's economic growth and industrial upgrade since the reform and opening up in 1978 and estimates the contribution of industrial restructuring to economic growth. With the years of schooling as the proxy variable of human capital, this paper describes changes in China's labor competence during the industrial restructuring process. Then, this paper estimates China's future human capital demand and shortage based on economic and demographic forecast. Lastly, this paper proposes recommendations for improving human capital in China with skills development and education. 展开更多
关键词 industrial structure industrial upgrade human capital labor competence China supply-side structural reforms
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Density and Fertilization Optimization for Highyielding Cultivation of a Wheat Variety Heibaoshi 1
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作者 周根友 夏华 陈启康 《Agricultural Science & Technology》 CAS 2017年第9期1691-1695,1750,共6页
The growth period, population tiller dynamics, plant characters, paniclegrain structure, yielding ability and stress resistance of a wheat variety Heibaoshi 1 were studied using a two-factor split plot design to inves... The growth period, population tiller dynamics, plant characters, paniclegrain structure, yielding ability and stress resistance of a wheat variety Heibaoshi 1 were studied using a two-factor split plot design to investigate the effects of different density and fertilizer levels on individual development and yield of Heibaoshi 1 in riparian region of Jiangsu Province. In addition, high-yielding agronomic measures were explored through multiple non-linear regression analysis. The results showed that low density was not conducive to the formation of panicles, while high density affected grain number per panicle; low fertilizer level restricted individual development, while high fertilizer level affected grain number per panicle and grain weight and was prone to leading to lodging. Reasonable combination of density and fertilizer could coordinate individual development and balance panicle, grain and weight, thus achieving a high yield. The yield potential was highest (7 384.3 kg/hm2) under density of 239.6×104 basic seedlings/hm2 and N level of 237.7 kg/hm2. When the planting density ranged from 200×104 to 270×104 basic seedlings/hm2 and the N level ranged from 220 to 260 kg/hm2 or the density basic seedling number ranged from 210×104/hm2 to 260×104/hm2 and the N level ranged from 210 to 270 kg/hm2, the yield could exceed 7 200 kg/hm2. 展开更多
关键词 Heibaoshi 1 Basic seedling N application rate Population quality YIELD
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A-BQ,a classification system for anisotropic rock mass based on China National Standard 被引量:8
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作者 GUO Song-feng QI Sheng-wen SAROGLOU Charalampos 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第10期3090-3102,共13页
The rock mass in nature is in most cases anisotropic,while the existing classifications are mostly developed with the assumption of isotropic conditions that not always meet the engineering requirements.In this study,... The rock mass in nature is in most cases anisotropic,while the existing classifications are mostly developed with the assumption of isotropic conditions that not always meet the engineering requirements.In this study,an anisotropic system based on China National Standard of BQ,named as A-BQ,is developed to address the classification of anisotropic rock mass incorporating the anisotropy degree as well as the quality of rock mass.Two series of basic rating factors are incorporated including inherent anisotropy and structure anisotropy.The anisotropy degree of rock mass is characterized by the ratio of maximum to minimum quality score and adjusted by the confining stress.The quality score of rock mass is determined by the key factors of anisotropic structure occurrence and the correction factors of stress state and groundwater condition.The quality of rock mass is characterized by a quality score and classified in five grades.The assessment of stability status and probable failure modes are also suggested for tunnel and slope engineering for different quality grades.Finally,two cases of tunnel and slope are presented to illustrate the application of the developed classification system into the rock masses under varied stress state. 展开更多
关键词 ANISOTROPY rock mass basic quality classification TUNNEL SLOPE
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Application of a novel detection approach based on non-dispersive infrared theory to the in-situ analysis on indicator gases from underground coal fire 被引量:10
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作者 TIAN Fu-chao LIANG Yun-tao +2 位作者 ZHU Hong-qing CHEN Ming-yi WANG Jin-cheng 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期1840-1855,共16页
Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability ... Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability and large monitoring error,of the existing underground coal fire monitoring technology,a novel monitoring system based on non-dispersive infrared(NDIR)spectroscopy is developed.In this study,first,the measurement principle of NDIR sensor,the gas concentration calculation and its temperature compensation algorithms were expounded.Next,taking CO and CH_(4) as examples,the liner correlation coefficients of absorbance and the temperature correction factors of the two indicator gases were calculated,and then the errors of concentration measurement for CO,CO_(2),CH_(4) and C_(2)H_(4) were further analyzed.The results disclose that the designed NDIR sensors can satisfy the requirements of industrial standards for monitoring the indicator gases for coal fire hazards.For the established NDIR-based monitoring system,the NDIRbased spectrum analyzer and its auxiliary equipment boast intrinsically safe and explosion-proof performances and can achieve real-time and in-situ detection of indicator gases when installed close to the coal fire risk area underground.Furthermore,a field application of the NDIR-based monitoring system in a coal mine shows that the NDIR-based spectrum analyzer has a permissible difference from the chromatography in measuring the concentrations of various indicator gases.Besides,the advantages of high accuracy,quick analysis and excellent security of the NDIR-based monitoring system have promoted its application in many coal mines. 展开更多
关键词 indicator gas coal spontaneous combustion infrared spectrometry bundle tube monitoring intrinsically safe
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基于无线传感器网络定位技术的图书馆智能管理创新 被引量:3
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作者 罗桦 陈勇 +2 位作者 张清 赵滟 黄猛 《大学图书情报学刊》 2016年第2期50-52,57,共4页
"互联网+"时代,信息技术的发展对图书馆的智能化管理工作提出了更高的要求。文章概述了无线传感器网络与定位技术,重点讨论了如何将WSN定位技术运用到图书智能管理,通过定位技术与大数据、云计算等信息技术的结合,推动图书馆... "互联网+"时代,信息技术的发展对图书馆的智能化管理工作提出了更高的要求。文章概述了无线传感器网络与定位技术,重点讨论了如何将WSN定位技术运用到图书智能管理,通过定位技术与大数据、云计算等信息技术的结合,推动图书馆智能系统建设和智能化发展。 展开更多
关键词 图书馆 智能管理 无线传感器网络 定位技术 互联网+
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Effect of Multiple Coatings of One-step Self-etching Adhesive on Microtensile Bond Strength to Primary Dentin 被引量:5
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作者 Lin Ma Jian-feng Zhou +3 位作者 Jian-guo Tan Quan Jing Ji-zhi Zhao Kuo Wan 《Chinese Medical Sciences Journal》 CAS CSCD 2011年第3期146-151,共6页
Objective To investigate the effect of multiple coatings of the one-step self-etching adhesive on immediate microtensile bond strength to primary dentin.Methods Twelve caries-free human primary molars were randomly di... Objective To investigate the effect of multiple coatings of the one-step self-etching adhesive on immediate microtensile bond strength to primary dentin.Methods Twelve caries-free human primary molars were randomly divided into 2 groups with 6 teeth each.In group 1,each tooth was hemisected into two halves.One half was assigned to control subgroup 1,which was bonded with a single-step self-etching adhesive according to the manufacturer's instructions;the other half was assigned to experimental subgroup 1 in which the adhesive was applied three times before light curing.In group 2,the teeth were also hemisected into two halves.One half was assigned to control subgroup 2,which was bonded with the single-step self-etching adhesive according to the manufacturer's instructions;the other half was assigned to experimental subgroup 2 in which three layers of adhesive were applied with light curing each successive layer.Microtensile bond strength was immediately tested after specimen preparation.Results When the adhesive was applied three times before light curing,the bond strength of the experimental subgroup 1(n=33,57.49±11.61 MPa) was higher than that of the control subgroup 1(n=31,49.71±11.43 MPa,P<0.05).When using the technique of applying multiple layers of adhesive with light curing each successive layer,no difference of immediate bond strength was observed between the control subgroup 2 and the experimental subgroup 2(P>0.05).Conclusion Multiple coatings of one-step self-etching adhesive can increase the immediate bond strength to primary dentin when using the technique of light-curing after applying three layers of adhesive. 展开更多
关键词 self-etching adhesive microtensile bond test primary dentin multiple coatings
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Design and performance analysis of wireless sensor network location node system for underground mine 被引量:10
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作者 CHEN Guang-zhu SHEN Chun-feng ZHOU Li-juan 《Mining Science and Technology》 EI CAS 2009年第6期813-818,共6页
Aiming at the application of a wireless sensor network to locating miners in underground mine,we design a wireless sensor network location node system,considering the communication performance and the intrinsic safety... Aiming at the application of a wireless sensor network to locating miners in underground mine,we design a wireless sensor network location node system,considering the communication performance and the intrinsic safety. The location node system consists of a mobile node,several fixed nodes,and a sink node,all of whose circuits were designed based on CC2430. A varistor and a RC circuit were used in the reset circuit of a sensor node to guarantee the intrinsic safety by reducing discharge energy,the theoretical analysis of the discharge energy shows that the reset circuit is an intrinsic safety one. The analysis and simulation about the performance of the location node system are discussed,such as network communication delay and packet loss rate,the results show that the highest network communication delay of the system is about 0.11 seconds,and the highest packet loss rate is about 0.13,which assures the location node system has a high reliability,and can locate miners in the underground mine. 展开更多
关键词 wireless sensor network location node network communication delay packet loss rate
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Experimental study on biaxial mechanical behavior of concrete suffered high temperature and constitutive model 被引量:1
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作者 张众 宋玉普 覃丽坤 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第5期679-685,共7页
Biaxial compression tests on plain concrete suffered high temperature ranging from 200 ℃ to 600 ℃ were carried out using the large-scale dynamic-static tri-axial concrete test system at the State Key Laboratory of C... Biaxial compression tests on plain concrete suffered high temperature ranging from 200 ℃ to 600 ℃ were carried out using the large-scale dynamic-static tri-axial concrete test system at the State Key Laboratory of Coastal and Offshore Engineering with designated stress ratios of 0, 0.25, 0.5, 0.75 and 1, respectively. The measured strength and strain were reported and the changes in both biaxial compressive failure envelopes and strains at peak stresses were analyzed. The regressive equation of initial elastic modulus in the biggest principal compressive stress direction was derived from test results. With the published results from previous biaxial tension-compression experiments, a three-parameter failure criterion has been proposed. A biaxial nonlinear elastic incremental constitutive model was developed for the compressive stress directions by using the equivalent uniaxial strain values deduced from test results. Analytical results obtained from the proposed biaxial constitutive model achieve good agreement with the experimental results. 展开更多
关键词 high temperature biaxial compression initial elastic modulus failure envelope constitutive model
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Design of intrinsically safe power supply 被引量:3
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作者 LI Rui-jin JIN Lin 《Journal of Coal Science & Engineering(China)》 2012年第4期443-448,共6页
Aiming to make a high power direct current supply safely used in coal mine production, this paper made a deep research on characteristics of intrinsically safe power supply, using the mathematical model established ac... Aiming to make a high power direct current supply safely used in coal mine production, this paper made a deep research on characteristics of intrinsically safe power supply, using the mathematical model established according to coal mine intrinsic safety standards. It provides theory support for the application of high power intrinsically safe power supply. The released energy of output short circuit of switch power supply, and the close related factors that influence the biggest output short-circuit spark discharge energy are the theoretical basis of the power supply. It is shown how to make a high power intrinsically safe power supply using the calculated values in the mathematical model, and take values from intrinsically safe requirements parameters scope, then this theoretical calculation value can be developed as the ultimate basis for research of the power supply. It gets the identification method of intrinsically safe from mathematics model of intrinsically safe power supply characteristics study, which solves the problem of theory and application of designing different power intrinsically safe power supply, and designs a kind of high power intrinsically safe power supply through this method. energy, flyback 展开更多
关键词 intrinsically safe circuit switching power supply output short circuit discharge characteristics output short circuit release
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Identification and quality evaluation of Lepidium meyenii. (Maca) based on gas chromatographic analysis of its essential oils from roots 被引量:5
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作者 金文闻 熊悦 余龙江 《Agricultural Science & Technology》 CAS 2006年第3期2-9,共8页
Lepidium meyeniiWalp. (Maca), a perennial herbaceous plant with narrow distdbution in the Andean region, was cultivated by local residents as early as 1600 B.C. It has high nutritional values and multiple medicinal ... Lepidium meyeniiWalp. (Maca), a perennial herbaceous plant with narrow distdbution in the Andean region, was cultivated by local residents as early as 1600 B.C. It has high nutritional values and multiple medicinal effects. In recent years the plant source of Maca has been greatly scarce since Maca products are increasingly becoming popular in the world. This makes the study urgent on the identification and quality evaluation of Maca materials. In present work, four Mace samples of different origins or handlings and three other natural plants, including radish, odental ginseng and American ginseng, were investigated. Their essential oils (steam distillates) of the hypogeal parts were weighed and analyzed by GC/MS. Through comparison of the characteristics of their chromatograms, it was found that the essential oil of Maca had unique GC/MS behaviors, and the characteristic peaks produced by the major essential oil components (Phenylacetonitrile, Benzaldehyde, 3-Methoxyphenylacetonitrile, etc) were distinct. Furthermore, the chromatograms of several Maca samples showed a similar qualitative pattern except for some differences in the quantitative composition, and the percentage of total essential oils in the samples varied from 0.88 % to 1.59 %. These behaviors and technologies can be applied to the identification of Maca materials in the markets and be a supplement to assess the quality of Maca matedals. 展开更多
关键词 Lepidium meyenii IDENTIFICATION essential oil GC/MS
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