Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： To reveal the survival strategy of plants in semi- arid coal mining subsidence areas faced with soil erosion stress, 2-3-year-old Artemisia ordosica plants were used as the test materials and in- situ root structure destruction tests were carried out at four levels: severe stress (P1), moderate stress (P2), mild stress (P3), and control (CK). The changes in growth indices, photosynthetic characteristics, and physiological traits of A. ordosica were measured. The results showed that soil erosion stress significantly inhibited the growth rate of A. ordosica, and that the greater the degree of simulated damage, the more significant the growth inhibition. After severe stress, the growth rates of plant height, crown width, branch length, and branch diameter of A. ordosica decreased by an average of 36.91%, 43.90%, 69.76%, and 66.76 %, respectively, compared to control plants. Soil erosion stress also conferred a significant negative effect on the photosynthesis of A. ordosica, and the greater the degree of damage, the stronger the negative effect. After severe stress, the net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration, transpiration rate, and chlorophyll content of A. ordosica decreased by 39.86%, 59.26%, 7.82%, 51.55%, and 12.33%, respectively, compared to control plants. After 70 days of erosion stress, the activities of superoside dismutase (SOD), peroxidase (POD), and oxidoreductase (CAT) in A. ordosica initially increased and later decreased, and tended to be stable when compared with the control. The malondialdehyde (MDA) content fluctuated within a certain range. Redundancy analysis showed that the level of SOD activity had the most significant effect on the photosynthetic characteristics of A. ordosica. Comprehensive analysis showed that the root fracture of A. ordosica caused by soil erosion in coal mining subsidence areas will reduce its growth rate and inhibit photosynthesis. However, A. ordosica can maintain its growth by regulating the activity of its antioxidase systems and can therefore be considered to be an ecological restoration plant species due to its excellent resistance and adaptability in erosive areas
Subjects: Library Science，Information Science >> Library Science submitted time 2023-08-26 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] The discovery of core patents is an important part in technological innovation, which is of great significance to the technological improvement and the patent strategy layout.[Method/process] This paper firstly defined the concept of core patent. Then, by introducing the original PageRank algorithm model, the improved PageRank——PatentRank (referred to as PTR) was put forward, which combining the cited times of patents and the patent age. Finally, we applied the new model to the field of OLED to identify the core patents.[Result/conclusion] We find that compared with the cited times, PTR can not only identify the core patents but also some basic important patents which provide the research ideas for the research of OLED technology. Besides, compared with the original PageRank algorithm, the values of PTR have higher degree of differentiation, and it can improve the PR results on the local scale.
Subjects: Library Science，Information Science >> Information Science submitted time 2023-04-01 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] Through literature review on the concept of disruptive technology at home and abroad and existing methods of identifying disruptive technology, this paper analyzes the existing problems and proposes possible research perspectives on future disruptive technology identification.[Method/process] Six identification methods of subversive technology were summarized by means of literature research, and their advantages and disadvantages were analyzed.[Result/conclusion] Disruptive technology identification method also has some disadvantages, such as the characteristics of disruptive technology classification is not clear, lack of quantitative research, the existing recognition methods lack of considering the correlation between technical knowledge, the future research should further strengthen the characteristics of disruptive technology research, and to consider the link between the knowledge characteristics, and strengthen the identification of disruptive technologies from the perspective of numerical breakthroughs in efficacy features and technology convergence. In addition, researchers should dig deeper into finer-grained technical topics.
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2022-05-29
Abstract：
Many methods and criteria of stability assessment have been proposed due to the complex dynamics of renewable power system. The physical implications of these methods/criteria and their scopes of adaptation are different. It is difficult to theoretically answer that, for certain stability issue, which stability criterion is suitable and whether the corresponding physical interpretation is reasonable. This paper was divided into two parts. The methods for assessing the adaptation of stability criteria were put forward, and the question whether the corresponding physical interpretations were reasonable were answered in part I. While the adaptation of each stability criterion was analyzed by applying the method and the physical interpretation of each stability problem was derived in part II. In part I, the derivation process of the existing stability criteria and their underlying physical significance were reviewed at first. Secondly, the selection principles of stability criteria were proposed from 3 aspects, namely stability equivalence, nominal performance and robust stability. And the quantitative index named loop gain sensitivity was proposed. Finally, the adaptation of several impedance criteria of grid-connected converters were analyzed.?It was shown that the nominal performance and robustness of these impedance criteria were not equivalent in frequency domain modal analysis. The adaptation of other typical stability criteria and the corresponding physical interpretation were analyzed in part II.
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Peer Review Status:
Awaiting Review
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2022-05-29
Abstract：
From the perspective of stability equivalence, nominal performance and robustness, the qualitative principles and quantitative evaluation index of stability criterion adaptation are proposed in Part Ⅰ. In addition, the adaptation of the existing stability criteria and the physical interpretation of instability corresponding to the suitable stability criterion are analyzed for the typical equipment in power system, such as synchronous machines, doubly-fed induction generators (DFIG) and converters in Part II. Thereby the stability classification of the renewable power system is discussed based on dominant output variable. Firstly, aiming at low-frequency and sub-synchronous oscillation/resonance (SSO/SSR) of synchronous machine, the rationality of the existing stability analysis methods and physical interpretation is verified by using the proposed evaluation index. Secondly, the proposed evaluation index is used to analyze the oscillation of converters and DFIG, and the suitable stability criterion, derivation mechanism and dominant output variable are further discussed. Finally, a novel idea of equipment stability classification based on physical mechanism and dominant output variables are proposed, which classifies equipment stability from the vector perspective into three categories: phase-dominated synchronous stability, amplitude-dominated voltage stability, and electrical resonance formed by their special combination. Issues such as the concept of wide-band oscillation, the distinction between equipment stability and system stability, and the extensibility of their classification are further explored.
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Peer Review Status:Awaiting Review
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2019-04-01 Cooperative journals: 《计算机应用研究》
Abstract： Aiming at the problem of low accuracy in the use of traditional recommendation algorithm in mobile environment, a matrix factorization algorithm based on context-aware was proposed. Based on the basic matrix factorization algorithm, the algorithm performed unknown score prediction by incorporating global bias and context bias. The advantage of this algorithm is that, on the one hand, the matrix factorization was used to make the scale of the matrix much smaller than the original scoring matrix; on the other hand, the algorithm fully integrated the influence of the situational elements on the score, making the prediction score more accurate. Experiments on the LDOS-CoMoDa dataset show that the proposed algorithm outperforms the user-based collaborative filtering algorithm, the basic matrix factorization algorithm and Baseline prediction algorithm.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2018-11-08 Cooperative journals: 《干旱区研究》
Abstract：为明确干旱矿区侵蚀发生后折力损伤对植物根系力学特性的影响及其受损后的自修复机制，利用HG100数显式推拉力计和自制便携式试验机台，对小叶锦鸡儿1~4 mm径级直根和侧根分支处未受损及受损自修复后的抗折力学特性进行研究。结果表明： 生长季初期，未受损小叶锦鸡儿根系极限抗折力与根径呈幂函数正相关，抗折强度与根径幂函数负相关，直根极限抗折力和抗折强度均大于侧根分支处； 折力损伤会明显抑制根系正常生长，小叶锦鸡儿根系受损自修复后，活性、生长量和保存率均低于平行对照，根径和根型均是影响这种抑制作用的重要因素，侧根分支处活性和保存率在受损后的减少程度显著大于直根； 小叶锦鸡儿根系受损自修复后，极限抗折力与抗折强度相比，生长季初期有所增加，但外力损伤会显著阻碍这种增长，导致其增长率显著低于平行对照，3个月后极限抗折力修复率为48.91%，抗折强度修复率为57.59%，说明根系受损后不会彻底丧失固土能力，通过自修复可以逐步恢复原有功能，但短期内自修复程度有限。直根极限抗折力修复率为60.55%，侧根分支处仅为36.34%，说明在同等外力荷载条件下，小叶锦鸡儿直根受损自修复能力显著大于侧根分支处，具备更强的再次抵御外力破坏的能力。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-17 Cooperative journals: 《计算机应用研究》
Abstract： With the rapid increase in the big data environment, frequent itemsets data mining faces in the actual incremental update problem. This paper proposes a parallel incremental updating algorithm based on MapReduce for frequent itemsets in frequent items ultrametric trees. The algorithm utilizes the support of frequent check ultrametric tree leaf node to determine the frequent itemsets and frequent itemsets using quasi strategies to optimize the parallel computing process, so as to improve the efficiency of data mining. According to the compared experiment results, it shows that the proposed algorithm is able to scan and update data efficiently, and has good scalability. It can be used for mining association rules in the incremental big data environment.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-21 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To explore the inhibitory effect of estrogen against metastasis of human hepatocellular carcinoma MHCC97H cells and explore the molecular mechanism. Methods The inhibitory effect of estrogen on the migration and invasion of MHCC97H cells was evaluated with wound healing assay and Transwell assay. Western blotting was used for investigating the expression of MMP-2, MMP-9, AKT and p-AKT in the cells treated with estrogen. Results Estrogen treatment significantly inhibited the migration and invasion of MHCC97H cells in a dose-dependent manner. Estrogen significantly down-regulated the protein expressions of MMP-2 and MMP-9 and lowered the phosphorylation level of AKT. Conclusion The anti-metastatic effect of estrogen involves inhibition of MMP-2 and MMP-9 in MHCC97H cells probably by regulating AKT signal pathway.
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