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INVESTIGATION OF 3d TRANSITION METALS BY IONIZATION LOSS SPECTROSCOPY
3d 金属电离损失谱研究

ZHANG QIANG-JI,CHEN NAI-QUN,HUA ZHONG-YI,
张强基
,陈乃群,华中一

物理学报 , 1991,
Abstract: A simple method has been developed in our laboratory, namely, lonization Loss Spectros-copy (ILS) for unoccupied DOS measurement which can be performed with existing Auger electron spectroscopy apparatus.The results of spin-orbit splitting and binding energy obtained by ILS are in excellent agreement with that of ESCA. The ILS spectra of 3d transition metals, Ti, Cr, Ni, Cu have been measured. The typical integral spectra exhibit a peak-like shape with different intensity and width which reflects the width of the unoccupied DOS. Since the unoccupied 3d DOS of Cu is zero, the ILS spectrum of Cu measured is shown by a step-like structure resulting from the flat, narrow 4s DOS.
INVESTIGATION OF PHYTOPLANKTON AND EVALUATION OF WATER QUALITY IN THE WATER SOURCE AREA OF THE MIDDLE LINE PROJECT FOR TRANSFERRING WATER FROM SOUTH TO NORTH
南水北调中线水源区浮游植物与水质评价

ZHANG Nai-Qun,DU Min-Hua,PANG Zhen-Ling,LI Yu-Ying,HU Lan-Qun,
张乃群
,杜敏华,庞振凌,李玉英,胡兰群

植物生态学报 , 2006,
Abstract: 通过2003年3月至2005年8月对南水北调中线水源区水体浮游植物的调查,结果表明:该水域共有浮游植物8门63属96种及变种,其中以硅藻的种类最多,其次是绿藻和蓝藻。藻类的细胞密度表现出明显的季节变化,夏季最高冬季最低。从近3年的浮游生物检测结果可知,整个水源区年平均藻类细胞密度为109.33×104cells·L-1,处于较低的水平,而且未检出水体重污染指示种,充分说明南水北调中线水源区富营养化程度较低。运用Margalef和Menkinick多样性指数对该水域的水质进行评价,数据显示2003~2005年该水源区的d值和α值,各采样点之间的差异并不显著,说明各采样点的水质营养状况虽有差异,但总体水平基本相当。水质评价结果:水体为寡污型,基本处于中营养状态。通过水生生物资源的调查,做好水源区的长期生态监测,可为建立中线水源区长期生态研究数据信息库及库区生态环境保护政策制定提供理论依据,对保证中线水质质量十分重要。
Spatiotemporal distribution of phytoplankton and trophic status in the water resource area of the middle route of China''''s South-to-North Water Transfer Project
南水北调中线水源区浮游植物时空分布及其营养状态

LI Yu-ying,Gao Wan-li,LI Jia-feng,WEN Zhen-zhong,LIU Hui,HU Lan-qun,ZHANG Nai-qun,CHENG Xu,
李玉英
,高宛莉,李家峰,文祯中,刘慧,胡兰群,张乃群,程序

生态学杂志 , 2008,
Abstract: 2004年3月-2006年5月,在南水北调中线水源区选择4个监测点进行了7次采样,获取了表层浮游植物和水质理化指标数据,采用污水生物系统法、营养状态指数法和单因子评价法综合评价了水源区的营养状态.结果表明:中线水源区浮游植物群落具有明显的时空变异性;浮游植物共有8门67属161种(含变种),硅藻占39%,污染指示种21属24种(含变种),β-中营养型占污染指示种的38%;在检出的浮游植物中未发现水体重污染指示种;水源区叶绿素a质量浓度为0.00425 mg·m-3,营养状态指数为0.0001;除总氮外,其他理化检测指标均符合Ⅰ类水质标准;综合评价水源区处于中营养状态.本研究可为中线水源区长期生态研究数据信息库的建立及库区环境保护政策的制定提供科学依据.
Analytical hierarchy process (AHP) evaluation of water quality in Danjiangkou reservoir-source of the middle line project to transfer water from south to north, China
层次分析法对南水北调中线水源区的水质评价

PANG Zhen-Ling,CHANG Hong-Jun,LI Yu-Ying,ZHANG Nai-Qun,DU Rui-Qing,HU Lan-Qun,
庞振凌
,常红军,李玉英,张乃群,杜瑞卿,胡兰群

生态学报 , 2008,
Abstract: Based on four seasons of monitoring phytoplankton communities and 9 water quality variables-total nitrogen (TN), total phosphorus (TP), chlorophyll a, chemical oxygen demand (COD), biological oxygen demand (BOD), dissolved oxygen (DO), secchi depth (SD), pH and water temperature (T) at three observatory sites, the water quality of Danjiangkou Reservoir was evaluated using Analytic Hierarchy Process (AHP). The biological diversity index showed the reservoir to be mesotrophic The water quality variables showed that the reservoir belonged to grade III according to the Environmental Quality Standard for Surface Water (GB3838-2002) of China, which suggested the reservoir status could be regarded as lightly polluted. AHP evaluation showed that the water quality was different between the three sample sites, of which the middle reservoir site was the cleanest site (pollution index =0.3619) and the upper reservoir site was the worst (pollution index =0.7755). This study indicates that more attention is required for the upstream pollution of the Danjiangkou Reservoir, and that AHP is a useful tool for water quality evaluation in surface water bodies such as Danjiangkou Reservoir.
Harmonic maps with potential from complete manifolds
Qun Chen
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883371
Abstract: Harmonic maps with potential from complete manifolds are considered. This is a new kind of maps more general than the usual harmonic maps relating to many interesting problems such as equilibrium system of ferromagnetic spin chain and Neumann motion. Aiming at the general properties, the author derives basic gradient estimates and then Liouville type results for these maps, which are interesting in constrast to those of the usual harmonic maps for the presence of potentials.
Symmetric Periodic Orbits in Three Sub-Problems of the N-body Problem
Nai-Chia Chen
Mathematics , 2013,
Abstract: We study three sub-problems of the N-body problem that have two degrees of freedom, namely the n-pyramidal problem, the planar double-polygon problem, and the spatial double-polygon problem. We prove the existence of several families of symmetric periodic orbits, including ``Schubart-like" orbits and brake orbits, by using topological shooting arguments.
Emergent Treatment of Source Water Contaminated by Representative Chemicals
水源水中典型化学品突发污染的应急处理

CHEN Bei-bei,GAO Nai-yun,LU Wen-min,SHANG Ya-bo,QIN Zu-qun,
陈蓓蓓
,高乃云,鲁文敏,尚亚波,秦祖群

环境科学 , 2009,
Abstract: 针对被典型化学品双酚A(BPA)与邻苯二甲酸二乙酯(DEP)污染原水的应急处理工艺进行了研究.结果表明,活性炭吸附可有效去除双酚A和DEP.拟二级动力学模型和Elovich模型较好地描述粉末活性炭对原水中BPA和DEP的吸附过程.中试条件下,50 mg/L的粉末活性炭可分别将原水中浓度约为500 μg/L的双酚A和3.3 mg/L的DEP处理达标.炭砂滤柱对2种化学品的动态吸附表明,BPA和DEP的去除率受它们初始浓度的影响较小,在滤速为5.1~15.3 m/h的范围内BPA和DEP的去除率基本不受滤速的影响.当同时采用粉末活性炭和炭砂滤柱工艺时, PAC的吸附过程是去除污染的主要阶段,炭砂滤柱可以作为粉末活性炭的有效补充保证一定的安全系数.KMnO4和Cl2均不能氧化DEP,3 mg/L的KMnO4和1.5 mg/L的Cl2可几乎完全氧化水中浓度为850 μg/L的BPA,BPA的氯化产物和KMnO4的氧化产物及其毒性有待于进一步研究. 1.5 mg/L高锰酸钾和PAC联用对去除DEP无协同作用,对去除BPA有促进作用.
Emergent Treatment of Source Water Contaminated by Representative Herbicide Molinate and Ametryn
水源水中典型除草剂禾大壮与莠灭净突发污染的应急处理

CHEN Bei-bei,GAO Nai-yun,LIU Cheng,YAO Juan-juan,SHANG Ya-bo,QIN Zu-qun,
陈蓓蓓
,高乃云,刘成,姚娟娟,尚亚波,秦祖群

环境科学 , 2008,
Abstract: 针对被典型除草剂禾大壮与莠灭净污染原水的应急处理工艺进行了研究.结果表明,活性炭吸附和预氯化是有效去除禾大壮和莠灭净的2种措施.拟二级动力学模型和Freundlich吸附等温线模型可分别较好地描述粉末活性炭对原水中禾大壮和莠灭净的吸附过程和吸附平衡.40 mg/L的粉末活性炭可将浓度为200ìg/L的禾大壮或莠灭净污染完全去除,粉末活性炭的最佳投加位置是混凝前20 min,颗粒活性炭柱(高20 cm)对2种农药的去除效果都较为显著,可以作为粉末活性炭的有效补充保证一定的安全系数.有效氯投加量为2.5 mg/L时虽然也可将2种农药氧化去除,但生成的产物及其毒性有待于进一步研究.粉末活性炭与1 mg/L的KMnO4预氧化联用并没有提高禾大壮和莠灭净的去除效果,粉末活性炭与1.5 mg/L的Cl2联用的去除效果与二者投加顺序有关.当浓度均为200 ìg/L左右的禾大壮与莠灭净同时污染原水时,粉末活性炭的投加量增至50 mg/L可将它们完全去除,Cl2的用量提高至3 mg/L可将它们全部氧化.
Optimization criteria for the performance of heat and mass transfer in indirect evaporative cooling systems
Fang Yuan,Qun Chen
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4903-3
Abstract: The wide application of evaporative cooling techniques in which the optimization criteria form the theoretical basis for improving evaporative cooling performance is essential for energy conservation and emission reduction. Based on exergy analysis and the entransy dissipation-based thermal resistance method, this contribution aims to investigate the effects of flow and area distributions in the optimization of the performance of indirect evaporative cooling systems. We first establish the relationships of exergy efficiency, entransy dissipation-based thermal resistance and cooling capacity of a typical indirect cooling system. Using the prescribed inlet parameters, the heat and mass transfer coefficients and the circulating water mass flow rate, we then numerically validate that when the cooling capacity reaches a maximum, the entransy dissipation-based thermal resistance falls to a minimum while the exergy efficiency is not at an extreme value. The result shows that the entransy dissipation-based thermal resistance, not the exergy efficiency, characterizes the heat transfer performance of an evaporative cooling system, which provides a more suitable method for evaluating and analyzing the indirect cooling system.
Application of entransy theory in the heat transfer optimization of flat-plate solar collectors
QinYi Li,Qun Chen
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4811-6
Abstract: The flat-plate solar collector is an important component in solar-thermal systems, and its heat transfer optimization is of great significance in terms of the efficiency of energy utilization. However, most existing flat-plate collectors adopt metallic absorber plates with uniform thickness, which often works against energy conservation. In this paper, to achieve the optimal heat transfer performance, we optimized the thickness distribution of the absorber with the constraint of fixed total material volume employing entransy theory. We first established the correspondence between the collector efficiency and the loss of entransy, and then proposed the constrained extreme-value problem and deduced the optimization criterion, namely a uniform temperature gradient, employing a variational method. Finally, on the basis of the optimization criterion, we carried out numerical simulations, with the results showing remarkable optimization effects. When irradiation, the ambient temperature and the wind speed are 800 W/m2, 300 K and 3 m/s, respectively, the collector efficiency is enhanced by 8.8% through optimization, which is equivalent to a copper saving of 30%. We also applied the thickness distribution optimized for wind speed of 3 m/s in heat transfer analysis with different wind speed conditions, and the collector efficiency was remarkably better than that for an absorber with uniform thickness.
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