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Maximization of Transfer Ratio and Minimization of Harmonics in Three Phase AC/AC Matrix Converter 三相交流/交流矩阵变换器中传输比最大化与谐波最小化
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/33416
Raheel Muzzammel, Umair Tahir
Energy saving and different working voltage applications are widely employing matrix converters. Matrix converters are used to convert three phase AC input voltages to three phase AC output voltages of required magnitude and frequency. Pulse width modulation is a technique used for converting three phase AC input to three phase AC output. In this research paper, pulse width modulation based matrix converter will be designed to acquire voltage of desired magnitude and frequency. Voltage transfer ratio will be maximized in this technique so that any desired voltage magnitude could be achieved. Secondly, harmonics will be made reduced in this design. Simulations will be performed in Matlab and characteristics of output waveform will be observed with respect to characteristics of input waveforms.
节能和不同工作电压的应用广泛采用矩阵转换器。矩阵转换器用于将三相AC输入电压转换为所需大小和频率的三相AC输出电压。脉宽调制是一种用于将三相交流输入转换为三相交流输出的技术。本文将设计一种基于脉宽调制的矩阵变换器,以获得所需幅值和频率的电压。在这种技术中,电压传输比将被最大化,从而可以实现任何期望的电压幅度。其次,在本设计中将减少谐波。将在Matlab中进行仿真,并将观察输出波形相对于输入波形的特性的特性。
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引用次数: 3
Computational Study of Aerodynamic Flow over NACA 4412 Airfoil NACA 4412翼型气动流动计算研究
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/31893
Moses Omolayo Petinrin, Vincent A. Onoja
The lift and drag coefficient plots for any airfoil provides a means for measuring its aerodynamic characteristics. These are very useful in deciding if a particular airfoil is appropriate for any particular application area. This study computationally predicts how the lift coefficient, drag coefficient and drag polar derived for the aerodynamic flow over the NACA 4412 airfoil vary with angles of attack. The effect of varying Reynolds number on the aerodynamic characteristics was also investigated. The finite-volume based computational fluid dynamics code; ANSYS Fluent was used to solve the continuity equation, the Reynolds Averaged Navier-Stokes equation and the turbulence transport equations governing the flow. For the range of Reynolds number considered, flow was taken as incompressible, steady and two-dimensional. Simulations were run for angles of attack ranging from -10° to 18° with an interval of 2° and for a Reynolds number range of 1.0 x 10 6 to 13.0 x 10 6 . Results at a given Reynolds number revealed a steady variation between lift coefficient and angle of attack within the pre-stall region and a gradually increasing curve for the drag coefficients. A constant stalling angle at 14° w ith gradually increasing value for the maximum lift coefficient was recorded as the Reynolds number increased. The drag polar was also found to be constant at 6° for all the ranges of R eynolds number. The results obtained showed that numerically solving for flow problems is a valid approach for obtaining the aerodynamic characteristics of an airfoil since the results were compared with data from wind tunnel tests.
升力和阻力系数图为任何翼型提供了一种测量其气动特性的手段。这些是非常有用的决定,如果一个特定的翼型是适合任何特定的应用领域。本研究计算预测如何升力系数,阻力系数和阻力极性推导为气动流量超过NACA 4412翼型随攻角变化。研究了不同雷诺数对气动特性的影响。基于有限体积的计算流体力学代码;利用ANSYS Fluent求解连续方程、Reynolds平均Navier-Stokes方程和控制流动的湍流输运方程。在考虑雷诺数范围内,将流动视为不可压缩、稳态和二维流动。模拟的迎角范围为-10°~ 18°,间隔为2°,雷诺数范围为1.0 × 10.6 ~ 13.0 × 10.6。在一定雷诺数下,升力系数和迎角在失速前区域呈稳定变化,阻力系数呈逐渐增大的曲线。随着雷诺数的增加,在14°w处有一个恒定的失速角,最大升力系数逐渐增大。在R -雷诺数的所有范围内,阻力极性均为6°不变。结果表明,数值求解流动问题是获得翼型气动特性的有效方法,并与风洞试验数据进行了比较。
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引用次数: 11
Spatial and Temporal Trends of Monthly, Seasonal and Annual Precipitation in Districts of Jharkhand in India 印度贾坎德邦地区月、季、年降水时空变化趋势
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/33502
S. Mali, B. Das, J. S. Choudhary, An Singh, B. Bhatt
Characterization of spatial variability and temporal trends in precipitation in a changing climate is vital to assess climate-induced changes to support adequate agricultural planning and water resources management strategies for the future. In this context, spatial and temporal variability in the precipitation over Jharkhand state in Eastern plateau and hill region is investigated. Spatial distribution of precipitation was mapped using ‘ordinary kriging’ geostatistical interpolation technique. A comprehensive precipitation trend and periodic analysis at the monthly and seasonal scale on a 40 year data series (1975-2014) for 18 locations in Jharkhand are presented using MannKendall and Sen’s slope methods. The seasonal and annual precipitation showed large spatial variability across the Jharkhand. Although, the spatial distribution of monsoon and annual precipitation are roughly similar, annual precipitation varied considerably in space due to the variations induced by pre-monsoon and winter precipitation. The statistical analysis revealed predominantly decreasing trends, both at the annual and seasonal scale. July precipitation showed significantly decreasing trend (-3.17 to -6.21 mm/year) in large number of districts (15), while the Original Research Article Mali et al.; BJAST, 20(6): 1-17, 2017; Article no.BJAST.33502 2 trend in May and other ‘monsoon’ months was not significant. Over the reference period, the negative trends in monsoon, winter and annual precipitation were significant for 61, 67 and 50% of the total districts analyzed with rate of decrease for monsoon and annual precipitation in the range of -5.3 to -13.0 and -5.3 to -15.9 mm/year, respectively. In view of the rainfall dependence of the agriculture in the state and decreasing trends of precipitation, the information presented in this paper can supports further climate change risk assessment and vulnerability adaptation planning.
气候变化中降水的空间变异性和时间趋势特征对于评估气候引起的变化以支持未来适当的农业规划和水资源管理战略至关重要。在此背景下,研究了贾坎德邦东部高原和丘陵地区降水的时空变化。利用“普通克里格”地统计插值技术绘制降水空间分布图。利用MannKendall和Sen’s slope方法,对贾坎德邦18个地点40年(1975-2014)的月、季尺度降水趋势进行了综合分析。贾坎德邦的季节和年降水量表现出较大的空间变异性。虽然季风和年降水的空间分布大致相似,但由于季风前和冬季降水引起的变化,年降水在空间上有很大的变化。统计分析显示,在年和季节尺度上,主要呈下降趋势。大部分地区(15)7月降水量呈显著减少趋势(-3.17 ~ -6.21 mm/年),而原研究文章Mali等;地球物理学报,20(6):1- 17,2017;文章no.BJAST。335022 . 5月及其他“季风”月份的趋势不显著。在参考期内,有61%、67%和50%的地区季风、冬季和年降水量呈显著负趋势,季风和年降水量的减少幅度分别在-5.3 ~ -13.0和-5.3 ~ -15.9 mm/年之间。鉴于该州农业对降雨的依赖性和降水的减少趋势,本文提供的信息可为进一步的气候变化风险评估和脆弱性适应规划提供支持。
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引用次数: 6
Competitive Adsorption of Cu(II) and Zn(II) from Binary Heavy Metal Solutions by Coffee Waste 咖啡渣对二元重金属溶液中Cu(II)和Zn(II)的竞争吸附
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/31336
Lovell Agwaramgbo, Simone Zulpo, S. Lira
Adsorption process has been proven to be one of the best water treatment technologies globally and activated carbon is undoubtedly considered a universal adsorbent for the removal of a variety of pollutants from water. However, widespread use of commercial activated carbon is often times restricted due to its higher costs. Attempts have been made to develop inexpensive adsorbents utilizing numerous agro-industrial and municipal waste materials. Use of waste materials as low-cost adsorbents is attractive due to their contribution in the reduction of costs or waste disposal, therefore, contributing to environmental protection. In this article was investigated the adsorption behavior of coffee waste when exposed to both single and binary metal component solutions under varying initial concentrations (1000, 500, and 250 ppm) and contact time (3 and 24 hrs.) It is evident from the literature that various low-cost adsorbents have shown good potential for the removal of various pollutants. However, there are few issues and drawbacks on the use of low-cost adsorbents in water treatment that have been discussed in this paper. Additionally, more research is needed to find the practical utility of low-cost adsorbents such as waste coffee on a commercial scale. After the exposure times, the residual concentrations of each heavy metal was determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), using EPA Method 6010. Results suggest that the percentage of adsorption of Cu and Zn decreases as the initial metal concentration increases. The coffee waste also has a higher affinity for Cu than Zn ion. The percentages for metal ion removal from the single metal solution are 250 ppm (73.47%), 500 ppm (46.45%), 1000 ppm (27.69%) for copper and 250 ppm (55.08%), 500 ppm (32.78%), and 1000 ppm (21.22%) for zinc. For the competitive metal removal from the binary Cu-Zn solutions, the percentages are 125 ppm (85.67%), 250 ppm (68.93%), and 500 ppm (46.62%) for copper and 125 ppm (49.67%), 250 ppm (7.73%), and 500 ppm (4.59%) for zinc, respectively.
吸附工艺已被证明是全球最好的水处理技术之一,活性炭无疑被认为是去除水中各种污染物的通用吸附剂。然而,商业活性炭的广泛使用往往由于其较高的成本而受到限制。已经尝试利用大量的农业工业和城市废料来开发廉价的吸附剂。使用废料作为低成本吸附剂是有吸引力的,因为它们有助于降低成本或废物处理,因此有助于环境保护。本文研究了咖啡废弃物在不同初始浓度(1000、500和250ppm)和接触时间(3和24小时)下暴露于单一和二元金属组分溶液时的吸附行为。从文献中可以明显看出,各种低成本吸附剂在去除各种污染物方面显示出良好的潜力。然而,本文讨论的在水处理中使用低成本吸附剂的问题和缺点很少。此外,还需要更多的研究来寻找低成本吸附剂(如商业规模的废咖啡)的实用性。暴露时间后,使用EPA方法6010,通过电感耦合等离子体原子发射光谱法(ICP-AES)测定每种重金属的残留浓度。结果表明,Cu和Zn的吸附率随着初始金属浓度的增加而降低。咖啡废料对Cu的亲和力也高于对Zn离子的亲和力。从单一金属溶液中去除金属离子的百分比为250ppm(73.47%)、500ppm(46.45%)、1000ppm(27.69%)(铜)和250ppm(55.08%)、500nm(32.78%)和1000ppm(21.22%)(锌)。对于从二元Cu-Zn溶液中竞争性去除金属,铜的百分比分别为125ppm(85.67%)、250ppm(68.93%)和500ppm(46.62%),锌的百分比分别是125ppm(49.67%)、250 ppm(7.73%)和500 ppm(4.59%)。
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引用次数: 3
A New Approach of Content Based Image Retrieval Using Color and Texture Features 一种利用颜色和纹理特征的基于内容的图像检索方法
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/33326
Hossain, Islam
The dramatic development of
的戏剧性发展
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引用次数: 11
Critical Analysis of Polycyclic Aromatic Hydrocarbons Ring Size Distribution in Marshy Soils and Sediments in Warri City and Its Environs, Southern Nigeria 尼日利亚南部Warri市及其周边沼泽土壤和沉积物中多环芳烃环尺寸分布的关键分析
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/32126
I. Agbozu, A. V. Bayowa, O. Oghama
This work was carried out in collaboration between all authors. Author IEA designed and supervised the study and wrote the protocol. Author AVB carried out and managed the analyses of the study. Authors IEA and AVB managed the literature searches while author OEO performed the statistical analyses. Authors IEA and OEO wrote the first draft of the manuscript. All authors read and approved the final manuscript. ABSTRACT This study was carried out to analyze the ring size distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in marshy soils and sediment samples in Warri City, Southern Nigeria. The samples were collected during dry and rainy seasons from four locations within Warri and a control location in Agbarho, 20km away. Levels of 16 priority PAHs listed in United States Environmental Protection Agency (USEPA) were determined using Gas Chromatography coupled with Flame Ionization detector (GC-FID). This study was carried from January to March and June to August, representing the dry and wet seasons respectively. It was observed that PAHs concentration was generally higher in dry than rainy seasons for soil and sediment samples. Furthermore, ring size analysis revealed that for soils, two to three-ringed as well as four-ringed PAHs were more predominant in Ugboroke location, five-ringed PAHs in Okotie and six-ringed PAHs in Ogunu location. Overall, five-ringed PAHs were more predominant in Okotie location in the dry season. However, for sediments, two to three-ringed as well as four-ringed PAHs were more predominant in Okotie location, five-ringed PAHs in Ogunu and six-ringed PAHs in Ugboroke location. Overall, two to three-ringed PAHs were more predominant in Okotie location in the dry season for sediment samples.
这项工作是由所有作者合作完成的。作者IEA设计并监督了这项研究,并编写了研究方案。作者AVB进行并管理了该研究的分析。作者IEA和AVB管理文献检索,而作者OEO进行统计分析。作者IEA和OEO撰写了手稿的初稿。所有作者阅读并批准了最终手稿。摘要本研究旨在分析尼日利亚南部瓦里市沼泽土壤和沉积物样品中多环芳烃(PAHs)的环径分布。这些样本是在旱季和雨季从瓦里的四个地点和20公里外Agbarho的一个对照地点采集的。使用气相色谱法和火焰离子化检测器(GC-FID)测定了美国环境保护局(USEPA)列出的16种优先多环芳烃的水平。这项研究于1月至3月和6月至8月进行,分别代表旱季和雨季。据观察,土壤和沉积物样品的多环芳烃浓度在旱季通常高于雨季。此外,环大小分析显示,对于土壤,在乌格博罗克地区,二环至三环和四环多环芳烃更为主要,在奥科蒂地区为五环多环芳烃,在奥古努地区为六环多环芳烃。总的来说,在旱季,五环多环芳烃在奥科蒂地区更为突出。然而,对于沉积物,奥科蒂地区的二环至三环和四环多环芳烃更为主要,奥古努地区的五环多环芳烃和乌格博罗克地区的六环多环芳烃。总的来说,在旱季,沉积物样本中,奥科蒂地区的二环至三环多环芳烃更为主要。
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引用次数: 3
Analysis of Reconfigurable Polarization Antenna as an EMI Sensor 可重构极化天线作为电磁干扰传感器的分析
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/31798
K. Mamta, R. Singh
Electromagnetic Interference (EMI) is of great concern in the present time of modern electronic systems. EMI measurement requires using a sensor to receive the radiation from the equipment in a suitable test environment. Antenna Factor decides the performance of the sensor. Finite Difference Time Domain (FDTD) numerical method has been used to predict the performance of antenna used as EMI sensor.
电磁干扰(EMI)是现代电子系统中备受关注的问题。EMI测量需要使用传感器在合适的测试环境中接收来自设备的辐射。天线系数决定传感器的性能。采用时域有限差分(FDTD)数值方法对EMI传感器天线的性能进行了预测。
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引用次数: 1
On the Riesz Integral Representation of Additives Set-Valued Maps (I) 关于附加集值映射的Riesz积分表示(I)
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/30901
Lakmon Kodjovi, S. Kenny, Ayassou Emmanuel, Tchariè Kokou
In this paper we generalize the Riesz integral representation for continuous linear maps associated with additive set-valued maps with values in the set of all closed bounded convex non-empty subsets of any Banach space. We deduce the Riesz integral representation results for set-valued maps, for vector-valued maps of Diestel-Uhl and for scalar-valued maps of Dunford-Schwartz.
本文推广了连续线性映射与加性集值映射相关的Riesz积分表示,其值在任意Banach空间的所有闭有界凸非空子集的集合中。我们推导了集合值映射、Diestel-Uhl的向量值映射和Dunford-Schwartz的标量值映射的Riesz积分表示结果。
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引用次数: 0
Comparative Evaluation of Some Nutrient Contents and Antifungal Properties of Ground Musa paradisiaca (Plantain) Peels and Leaves 芭蕉皮和叶某些营养成分及抗真菌性能的比较评价
Pub Date : 2017-01-10 DOI: 10.9734/bjast/2017/28393
Anthony Cemaluk C. Egbuonu, Wisdom O. Nneji, Chimnonye A. Ukasoanya
Musa paradisiaca (plantain) fruit peels and the plant leaves may have some nutrients and antifungal properties. Thus, millimeter, mm) against Candida albicans, however, the activity of the ethanol extract of the leaves (15.67±0.58) was higher (p<0.05) than that of the ethanol extract of the peels and the aqueous extract of the peels and leaves. The difference in activity against C. albicans between the samples extracts in terms of either the same or the different extracting solvent was significant (p<0.05) but the overall difference between the samples compared to the extracting solvents (±0.67) was the same hence non-significant (p>0.05). A similar trend was recorded for the activity of the ethanol and aqueous extracts of the peels and leaves against P. notatum . Thus, the plantain peels and leaves could be alternative source for vitamin C. The extracts (aqueous and ethanol) had activity against C. albicans and P. notatum hence may be useful in managing such pathogen-induced ailments. Overall negligible difference in activity against either C. albicans or P. notatum in terms of samples and the extracting solvents was suggested and this may be an underlying useful trend for comparing the overall antimicrobial activity of different samples and solvents, hence warrants a follow up.
芭蕉果皮和植物叶片可能具有一定的营养和抗真菌特性。因此,对白色念珠菌的抑制作用(mm, mm),叶乙醇提取物的抑制作用(15.67±0.58)较高(p0.05)。类似的趋势记录了乙醇和水提取物的果皮和叶片的活性对假葡萄。因此,车前草的皮和叶可以作为维生素c的替代来源。提取物(水和乙醇)对白色念珠菌和假单胞菌有活性,因此可能对治疗这些病原体引起的疾病有用。在样品和提取溶剂方面,对白色念珠菌或假单胞菌的活性总体上可以忽略不计,这可能是比较不同样品和溶剂的总体抗菌活性的潜在有用趋势,因此值得后续研究。
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引用次数: 0
Geochemical Characterization and Protolith of the Migmatite-Gneisses of Tandama Area, Katsina State, NW Nigeria 尼日利亚西北部卡齐纳州Tandama地区混合岩片麻岩的地球化学特征和原岩
Pub Date : 2017-01-10 DOI: 10.9734/BJAST/2017/30117
Idzi Alaku, O. Moshood, A. Agbor, A. Amos
Migmatite-gneisses, which include migmatite, granite gneiss, and augen gneiss, underlie more than 70% of Tandama area, in North-western Nigeria. They are associated with schists, and are intruded by granites and pegmatites. These rocks are thought to have undergone a reworking during the Pan-African Orogeny. The aim of this research is to present results of geochemical investigation of Migmatite-gneiss Complex in the study area with a view to determine their geochemical characteristics and petrogenesis. Whole rock geochemical analyses have been used to evaluate the characteristics, petrogenesis and mode of emplacement of the protoliths. Geochemically, these rocks show granitic affinities. They are metaluminous to weakly peraluminous I-type, with S-type characteristic, magnesian to ferroan and alkali calcic and calcic. The protoliths could have been derived from the partial melting of tonalitic to granodioritic crustal rocks at low pressure, thus, producing metaluminous to slightly peraluminous high-silica, ferroan, alkali-calcic to calc-alkali melts, which is why it has some S-type character. These varying features are an indication that the protoliths are derived from mainly crustal melt mingled with mantle-derived component. The varying REEs and trace elements pattern displayed by the rocks is typical signature of arc rocks or continental crustal materials: the LREEs and LILE enrichment along with Rb, K, Pb, and negative Nb, Ta, Ti are evident of this signature. The incompatible trace elements show similarity to those of continental crustal rocks as indicated by the ratios in Th/U (2.21 12.4), Th/Yb (2.60 – 90.95), Ta/Yb (0.03 - 1.43), Ce/Pb (mainly 0.30 – 29.23) and high Ba/Nb (8.56 – 2402), the values of Sr/Y are generally<100, which is an indication of subduction-related rocks,the trend in Sr/Y ratio relative to Y contents in the rocks reflects essentially two types of felsic protolith namely crustal melts and slab melts. Similarly, the magnesian characteristic indicates close affinity to relatively hydrous, oxidizing melts, which is broadly typical of settings related to subduction. The high-K nature is characteristics of crustal rocks derived from remelting and differentiation of arc-accretionary complex crust. The rare earth element (REE) distribution shows that the migmatite-gneisses are enriched in the lighter rare earth elements (LREE) Sm, Pr, Nd, La and Ce, in that order of increasing abundance, with average values of 4.81 ppm, 7.90 ppm, 27.50 ppm, 38.44 ppm, 68.22ppm, respectively; and relatively depleted in the heavy rare earth elements (HREE) Lu, Tm, Tb, Ho, Yb and Er, with average values ranging 0.28 ppm, 0.30 ppm, 0.58 ppm, 0.65ppm, 1.91 ppm and 1.88 ppm respectively, and they exhibit negative EU anomaly, indicating that the rocks are highly fractionated. REE-chondrite normalized spider plot and plots in the chemical discrimination diagrams including the Y versus Nb plot, show that the protoliths were derived from partial melting
混辉岩片麻岩,包括混辉岩、花岗片麻岩和奥根片麻岩,占尼日利亚西北部Tandama地区的70%以上。它们与片岩伴生,并被花岗岩和伟晶岩侵入。这些岩石被认为在泛非造山运动期间经历了改造。摘要介绍研究区杂岩片麻岩杂岩地球化学调查结果,探讨其地球化学特征和岩石成因。利用全岩地球化学分析对原岩的特征、成因和侵位方式进行了评价。地球化学上,这些岩石显示出花岗岩的亲和力。它们是铝质到弱过铝质的i型,具有s型特征,镁质到铁质,碱钙和钙。原岩可能是在低压条件下由渐长质到花岗闪长质地壳岩石部分熔融而成,形成了含铝质到略过铝质的高硅、铁、碱钙到钙碱熔体,具有一定的s型特征。这些不同的特征表明原岩主要来源于地壳熔体,并混合有地幔源成分。岩石中稀土元素和微量元素的变化模式是弧岩或大陆地壳物质的典型特征,lree和LILE的富集与Rb、K、Pb和负Nb、Ta、Ti的富集是这一特征的明显体现。不相容微量元素与大陆地壳岩石相似,Th/U(2.21 12.4)、Th/Yb(2.60 ~ 90.95)、Ta/Yb(0.03 ~ 1.43)、Ce/Pb(主要为0.30 ~ 29.23)和Ba/Nb(8.56 ~ 2402)较高,Sr/Y值普遍<100,表明岩石为俯冲相关岩石,岩石中Sr/Y比值与Y含量的变化趋势主要反映了地壳熔体和板块熔体两种长英质原岩类型。同样,镁质特征表明与相对含水的氧化性熔体密切相关,这是与俯冲有关的典型环境。高钾性是弧-增生复合体地壳重熔分异形成的地壳岩石特征。稀土元素(REE)分布表明,杂岩片麻岩富集较轻的稀土元素(LREE) Sm、Pr、Nd、La和Ce,丰度依次递增,平均值分别为4.81 ppm、7.90 ppm、27.50 ppm、38.44 ppm、68.22ppm;重稀土元素(HREE) Lu、Tm、Tb、Ho、Yb和Er相对富集,平均值分别为0.28 ppm、0.30 ppm、0.58 ppm、0.65ppm、1.91 ppm和1.88 ppm, EU呈负异常,表明岩石分选程度较高。ree -球粒陨石归一化蜘蛛图和化学分辨图(包括Y - Nb图)显示,原岩来自于位于火山弧(VAG) -碰撞花岗岩(Syn-COLG)构造背景下的杂化花岗岩岩浆的部分熔融和分异。因此,表明该地区混杂岩片麻岩的火成岩前体来自不同的来源和深度。
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引用次数: 0
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