最新刊期
卷 58 ， 期 4 ， 2019
- 摘要：The stone tool is a key symbol of productivity and production mode in the Stone Age. Ancient Hanxia nephrite mining site in Dunhuang was archeologically recognized as the oldest jade mining site discovered in China, its mining tools, i.e. stone hammers, and their rock materials including the petrological and geochemical characteristics may provide important information for revealing their material sources and the productivity at that time. In this paper, nine typical stone hammers were selected for petrological and geochemical analysis using polarizing microscope, XRF, and ICP-MS. The results showed that the stone hammers were made of diabase, basalt, dacite, granodiorite porphyrite and diorite porphyrite rocks. These rocks were characterized by the petrogeochemistry of igneous rocks formed within intraplate or volcanic arc environment, and are consistent with local igneous rocks within tens of kilometers of the site in Dunhuang area. Further comparison of the stone hammers and relative local igneous rocks in macroscopic features, microtexture, main and trace elements, and tectonic environment can infer that, except for some pebble hammers, the stone hammers were probably processed from local igneous rocks, especially those hard & dense-textured volcanic or subvolcanic rocks at Sanwei mountain nephrite mine or neighborly close-by, maybe 100 km around. Based on the scattered position of the stone hammers in the mining site and by contrasting with those stone hammers from other sites, we think the stone hammers were used as separation tools at Hanxia nephrite mining site, but more detailed research needs to do to find out their significance and value in understanding mining personnel from the stone hammer-reflected human behaviour and technical gestures in shape & structure in social system.
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发布时间：2023-12-11 - 摘要：Researching on the Mesozoic magmatism is critical to understanding the tectonic evolution of the Cathaysia Block, and therefore has become a hot topic in the past decade. Numerous petrological and geochemical studies were implemented in the eastern and middle parts of the block, but few studies focused the southernmost area in western Guandong Province. Therefore, the geochronological, geochemical, and Hf isotopic data from the Fenghuangshan granitoids, which are located at the southern margin of the Cathaysia Block, were used to constrain the crystallization age, petrogenesis and tectonic environment. The Fenghuangshan granitoids are dominated by biotitebearing monzogranites and biotite-bearing syenogranites. LA-ICP-MS zircon U-Pb data show that the former is (156±2) Ma and the latter is (158±3) Ma, respectively. All of the samples contain high silicon (SiO2=72.66%-76.63%), high alkali (Na2O+K2O =7.89%~9.43%), and low magnesium (MgO=0.05%-0.54%) concentrations. They show weakly peraluminous characteristics (A/CNK=1.02~1.04). The samples are enriched in Rb, Th, K and depleted in Ba, P, Sr, Ti, with a negative correlation between SiO2and P2O5. Mineralogical and geochemical features suggest that the biotite-bearing syenogranite is I-type granite. By contrast, the biotite-bearing monzogranite falls into the area of highly fractionated I-type granite, with high differentiation index (DI=93.91-95.74), high Rb/Sr (=99.12-243.75) and Rb/Ba (=67.45-203.80) ratio, low consolidation index (SI=0.48-0.66) as well as significant negative Eu anomalies (δEu=0.01~0.02). The samples of monzogranite and syenogranite have relatively homogeneous Hf isotopic compositions, withεHf(t) values and two-stage model ages (TDM2) of -9.4 to-5.4 and 1 545-1 804 Ma, respectively. The Hf isotopic features indicated that the monzogranites and syenogranites might share a same magma source, which was sourced from reworking of the Paleoproterozoic-Mesoproterozoic crust in the Jurassic. Combined with the previous studies, the Fenghuangshan pluton was suggested to be formed by underplating of the mantle-derived magma in an extensional tectonic setting, which was related to the roll-back or breakup of the subducting oceanic lithosphere.关键词：Yanshanian;U-Pb chronology;Itype granites;geochemistry;Hf isotopes
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发布时间：2023-12-11 - 摘要：The Yushui deposit, located in the middle part of the Late Paleozoic depression in eastern Guangdong province, is characterized by high-grade copper content in a small area. In this study, the geochemical characteristics of elements and their correlation in the ores are analyzed to provide evidence for the genesis of the Yushui copper deposit. The results show that copper content can reach a maximum of 59.22 % and is associated with a large amount of Ag (＞10 000 μg/g in maximum). There is a positive correlation between Ag and Cu, indicating that Ag and Cu share the same origin. The total amounts of REEs in the ores vary from 3.07 to 23 223.00 μg/g, partially reaching industrial grade, and show a pattern being rich in heavy REE enrichment and deficient in light REE. The total REEs is positively correlated with Y, P, Sb, Bi, Be and As in those samples of high REE contents, which suggests that the high REE contents may be caused by hydrothermal superposition. Combining the variation trend of Y/Ho and La/Ho, the negative anomaly in Eu and weakly negative anomaly in Ce, it can be deduced that the Yushui copper deposit is the sedimentary exhalative deposits and affected by the transformation of later-stage hydrothermal alternation.关键词：element geochemistry;elemental correlation;the Yushui copper deposit;eastern Guangdong
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发布时间：2023-12-11 - 摘要：CFD simulation is utilized to analyze the wind environment and outdoor comfort surrounding a typical super high-rise building cluster in Zhuhai by using a software PHOENICS with consideration of local climatic conditions. The results are as follows: 1) The direction of dominant wind changes from season to season in the research district, which is north (N) in winter, south-southwest (SSW) in summer and east-northeast (ENE) in the transitional season, resulting in the variations of the wind and comfort in down ground and building facade. 2) When the wind is blowing from the high-rise buildings to the low-rise buildings, the floor ventilation and comfort between the high-rise buildings and the low-rise buildings are poor, because of blockage effects. In the meanwhile, the well ventilated areas, for example the upwind side and both sides of the high-rise buildings, are more comfortable comparably. 3) When the wind blows from the lower buildings to the high-rise buildings, the ventilation conditions of the spaces between buildings are better, since the flows pass through the lower buildings and get amplified. And the ventilation and comfort of the facade are better in comparison with the situation when wind blows from the high-rise buildings to the low-rise buildings. 4) As the wind speed increases with the increase of height, people will feel uncomfortable in the upwind face and the corner of both sides of the high-rise buildings and the ventilation corridor, where wind speed exceeds Grade 3.关键词：super high-rise building cluster;wind environment;comfort degree;CFD simulation
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发布时间：2023-12-11 - 摘要：The study aimed to establish the fingerprint of Jiangu injection (JGI) by the high performance liquid chromatography (HPLC), and analyze the correlation between the raw herbs and effective constituents in JGI. The established method is simple, rapid and reproducible, which is suitable for the production and quality control of JGI．关键词：Jiangu injection;Premna fulvaCraib;intermediate;fingerprint chromatography;correlation
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发布时间：2023-12-11 - 摘要：The morphological characteristics of the Polynemid fish species distributed in the China Sea are very similar, which can easily lead to classification confusion In this study, we applied DNA barcode technology to analyze the genetic differences betweenEleutheronema tetradactylumand its related speciesEleutheronema rhadinum. Mitochondrial COI sequences were obtained from four samples of each species. Among the 655 bp sequences, 87 sites were variable. The nucleotide diversity was 0.132 82, and the sequence homology was 93.34%. Moreover，the genetic distance based on the kimura 2parameter model is 0.151, larger than minimum species distance of 0.02. Neighbor-joining phylogenetic analysis revealed thatE. tetradactylumandE. rhadinumare two different but closely related species from the same genus. Using ten random primers, we obtained some specific fragments, and then converted one of them (about 1 300 bp in length, amplified by primer S4) to SCAR marker. Two SCAR markers, SCAR1 (469 bp fragment, 62 ℃ annealing temperature) and SCAR5 (606 bp, 56 ℃), were obtained successfully for the species identification ofE. tetradactylumand its related species. This study would provide technical support for the genetic background research and germplasm conservation of the Polynemid fish species.关键词：Eleutheronema tetradactylum;Eleutheronema rhadinum;DNA barcoding;SCAR
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发布时间：2023-12-11 - 摘要：A cationic glycogen derivative conjugated with vitamin B12 (VB12) residues (GD-VB12) was synthesized and characterized using FTIR and1H NMR spectroscopy, which could be used as a nano-carrier for oral delivery of drugs. The degree of distribution of diethylenetriamine and VB12 residues were determined to be 0.9% and 0.6% using1H NMR integral method and UV-vis spectroscopy, respectively. The GD-VB12 derivative was observed as particles with irregular shape in the sizes ranging from 200 to 300 nm. It exhibited a high stability in the simulated gastric medium and the simulated small intestinal medium, and is beneficial for safe delivery of drugs through the digestive tract. The GD-VB12 derivative could be rapidly degraded by glycogen phosphorylase a within 1 h. Therefore, the GD-VB12 derivative possesses potential as a carrier for oral delivery of drugs safely and targeted release of drugs in the liver and muscle.关键词：glycogen;glycogen derivatives;synthesis;stability in digestive tract;biodegradability
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发布时间：2023-12-11 - 摘要：The title reaction was researched in the theory by ONIOM method conbined with quantum mechanics and molecular mechanics, and the SMD model method based on self consistent reaction field (SCRF) theory. The study showed that there were two channels a, b in the title reaction. In channel a the hydroxyl radical water molecule cluster acted withα-H and amino nitrogen through hydrogen bond to form substrate, and in channel b that acted withα-H and carbonyl oxygen through hydrogen bond to form substrate. Calculations of potential energy surface showed that with hydroxyl radical and water clusters as the proton transfer media, optical isomerism of α-Ala was induced by water molecules pullingα-H, and in water vapor environment, channel a was the dominant one and the energy barrier of the rate-determining step was 136.1 kJ/mol, but in water liquid environment, the dominant channel was b, the intrinsic barrier of transition state was 78.1 kJ/mol. The dominant channel whereα-Ala damage induced by theα-H abstraction of hydroxyl radical assisted with water molecule cluster was a, the energy barrier of the rate-determining step was 25.3 kJ/mol, which was reduced to 22.1 kJ/mol by water solvent effect. The results showed that hydroxyl radical can make optical isomerism and the damage ofα-Ala occurs simultaneously in water liquid phase environment, and the damage had obvious advantage in competition. The confinement effect of MOR zeolite changed optical isomerism mechanism ofα-Ala and played a better role in catalysis.
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发布时间：2023-12-11 - 摘要：Given a graphG=(V,E)with each edge having a positive integer weight, and a positive integerkcanVbe partitioned into two disjoint subsetsV1and V2so that the sum of weights of the edges with one end inV1and another end inV2is at leastk? This problem is called the Maximum Cut Problem, which is an NPC problem. When the weight of each edge of G is 1, it is still an NPC problem. A highly efficient algorithm is designed to solve the Maximum Cut Problem with the weight of each edge to be 1 in Halin graphs. The time complexity of the algorithm is O(n)， where n=(|V(G)| .关键词：maximum cut;extendible;shrinking fan;odd face
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发布时间：2023-12-11 - 摘要：Multi-DAG task scheduling problem is a hotspot of current research in distributed heterogeneous environment. In order to improve the efficiency of task scheduling and resource utilization, the scheduling order of each DAG and the scheduling order between tasks within each DAG become the key task scheduling problem. A multi-DAG task scheduling model based on distributed heterogeneous computing environment and multi-DAG task scheduling algorithm MDTS(Multi-Dags Task Scheduling algorithm) are proposed. Firstly, multiple DAG tasks are merged into one DAG by adding an entry task node and an exit task node. secondly tasks are sorted according to the variance of computing cost and average communication cost of each task node. Finally, processors are scheduled according to the order from high to low based on HEFT algorithm. Experiments show that MDTS algorithm is superior to Sequential and Interleave algorithm in task scheduling makespan, average waiting time and average Slack.关键词：task scheduling;makespan;average waiting time;directed acyclic graph
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发布时间：2023-12-11 - 摘要：The oscillation of second-order half-linear variable delay damped dynamic equation［a(t)|xΔ(t)|λ－1xΔ(t)]Δ+b(t)|xΔ(t)|λ－1xΔ(t)+p(t)|x(δ(t))|λ－1x(δ(t))=0 is investigated on a time scaleTin which the equation is noncanonical, i.e.,∫∞t0［a－1(s)e－b/a(st0)］1/λΔs<∞. By using the generalized Riccati transformation and the calculus theory on the time scales, and in combination with some inequality technique, some new oscillation criteria for the equation are established. It generalizes, improves and enriches the known results.关键词：oscillation;time scales;functional dynamic equations;Riccati substitutions;variable delay
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发布时间：2023-12-11 - 摘要：Firstly, the formula of the fraction of positive integernis not more than 2 is obtained by using the recursive method. Secondly, the bijection of the ordered split sets between the fraction of positive integernis not more than 2 and the fraction of positive integern+2 is not less than 2 is established, so that the formula for calculating the ordered split number of the positive integern+2 is not less than 2 is obtained. Finally, when the fraction of positive integernis not more than 3 or 4, and is 2, 3 or 4, the recursive relations of the ordered split number are given.关键词：components;recursive relation;bijection
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发布时间：2023-12-11 - 摘要：An eco-organic ester polymer named as Aqua-Dispersing-Nano-Binder (ADNB) was used to stabilize silty clay distributed in Guangdong Province. A series of experiences such as unconfined compressive strength test, direct shear test, osmotic test, Scanning Electron Microscope test (SEM), particle size analysis and Mercury Intrusion Porosimetry test (MIP) have been performed with different ADNB content and the variation regularity of strength, permeability and soil structure was obtained. The strength tests show that ADNB can effectively improve the soil strength which increases with the ADNB dosages and the ADNB can be fully effective after approximately 3 days of conservation of soil; ADNB can improve the structure of soils by bonding and wrapping fine particles which is summarized as “granular recombination” structure improvement mode; Osmotic test shows that the permeability coefficient of the soil increases and then decreases with the increasing ADNB dosages, and the microscopic study shows that the elastic film formed in the surface and pores of soils increases the grain-to-particle connection, thus improving the stability of the soil. ADNB provides a good substrate environment for vegetation growth by improving soil stability, structural optimization and improved soil permeability, thus can be used as ecological material for slope protection.关键词：Aqua-Dispersing-Nano-Binder;soil improvement;microscopic structure;permeability;mechanism analysis
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发布时间：2023-12-11 - 摘要：The AVL-FIRE software was used to study the effect of water injection to combustion in the YC6G series diesel engine during the intake stroke. Specifically, the influence of intake water injection on engine internal pressure, temperature, emission and ultimately performance was analyzed. Simulation results show that water injection of the supercharged engine has little effect on the average internal temperature and pressure of the engine cylinder but it can still reduce the peak temperature of the cylinder to a certain extent. The effect of water injection at the intake stroke on the exhaust emission is very significant. When the water injection mass fraction increased by 5%, soot production would decrease by approximately 10% and NOxemissions decreased to 0.21% over when water was not injected. Therefore, the intake stroke boosting water injection effectively improves the combustion inside the diesel engine and reduces exhaust emissions.
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发布时间：2023-12-11 - 摘要：It has been one of the essential study methods to analyze traffic condition via the floating car data (FCD) in transportation field. The sparsity of FCD, Nevertheless, is a hindrance to researches. After analyzing the data missing features of road network, this paper put forward a filling model for the sparse FCD, which fills the random data missing based on Naive Bayes classifier and double fills the multiple data missing based on dynamic time warping. By combining the two methods mentioned above and applying them to field cases, filling the roads’ traffic flow velocity data missing can substantially increase network coverage rate of FCD and reduce the impact on collecting, launching and forecasting the traffic flow velocity data brought by the FCD missing.关键词：floating car;data missing;Naive Bayes;dynamic time warping;speed estimation
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发布时间：2023-12-11 - 摘要：For the identification of series resonance in power system branches, the identification method of branch series resonance based on modified nodal admittance matrix modal method is proposed. First of all, when the network matrix modal method is used to identify the parallel connection of the nodes and the series resonance points of the loop, the corresponding resonant points are found to coincide. The theoretical analysis shows that the smaller the branch impedance ratio, the higher the coincidence degree of the corresponding series and parallel resonant points. Then, for branch series resonance, it is transformed into loop series resonance by adding virtual branch, and further transformed into parallel resonance identification by using the theory of system series-parallel resonance coincidence. Finally, the feasibility and correctness of the three node system and the IEEE14 node system are verified by simulation analysis.关键词：resonance mode analysis（RMA）;branch series resonance;node admittance matrix;loop impedance matrix;impedance ratio
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发布时间：2023-12-11 - 摘要：Aiming at the problem of slow response speed and low regulation efficiency of traditional PID wind speed regulation and control, an adaptive fuzzy PID control strategy is designed for wind speed regulation and control of wind turbines. The control system consists of four parts: data acquisition, fuzzy reasoning, instruction execution and data feedback. Through the experimental platform built, the traditional PID control method and adaptive fuzzy PID control method are compared. The experimental results show that the adaptive fuzzy PID adjustment response speed is fast and the efficiency is high, at the same time the adjustment effect is obviously better than the traditional PID adjustment.关键词：PID;fuzzy reasoning;draught fan;wind speed regulation
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发布时间：2023-12-11 - 摘要：Aiming at the problem of slow response speed and low regulation efficiency of traditional PID wind speed regulation and control, an adaptive fuzzy PID control strategy is designed for wind speed regulation and control of wind turbines. The control system consists of four parts: data acquisition, fuzzy reasoning, instruction execution and data feedback. Through the experimental platform built, the traditional PID control method and adaptive fuzzy PID control method are compared. The experimental results show that the adaptive fuzzy PID adjustment response speed is fast and the efficiency is high, at the same time the adjustment effect is obviously better than the traditional PID adjustment.关键词：PID;fuzzy reasoning;draught fan;wind speed regulation
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发布时间：2023-12-11
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