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2021 ◽  
Vol 13 (23) ◽  
pp. 4785
Author(s):  
Hao Fu ◽  
Wei Zhao ◽  
Qiqi Zhan ◽  
Mengjiao Yang ◽  
Donghong Xiong ◽  
...  

Afforestation is one of the most efficient ways to control land desertification in the middle section of the Yarlung Zangbo River (YZR) valley. However, the lack of a quantitative way to record the planting time of artificial forest (AF) constrains further management for these forests. The long-term archived Landsat images (including the Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI)) provide a good opportunity to capture the temporal change information about AF plantations. Under the condition that there would be an abrupt increasing trend in the normalized difference vegetation index (NDVI) time-series curve after afforestation, and this characteristic can be thought of as the indicator of the AF planting time. To extract the indicator, an algorithm based on the Google Earth Engine (GEE) for detecting this trend change point (TCP) on the maximum NDVI time series within the growing season (May to September) was proposed. In this algorithm, the time-series NDVI was initially smoothed and segmented into two subspaces. Then, a trend change indicator Sdiff was calculated with the difference between the fitting slopes of the subspaces before and after each target point. A self-adaptive method was applied to the NDVI series to find the right year with the maximum TCP, which is recorded as the AF planting time. Based on the proposed method, the AF planting time of the middle section of the YZR valley from 1988 to 2020 was derived. The detected afforestation temporal information was validated by 222 samples collected from the field survey, with a Pearson correlation coefficient of 0.93 and a root mean squared error (RMSE) of 2.95 years. Meanwhile, the area distribution of the AF planted each year has good temporal consistency with the implementation of the eco-reconstruction project. Overall, the study provides a good way to map AF planting times that is not only helpful for sustainable management of AF areas but also provides a basis for further research on the impact of afforestation on desertification control.


2021 ◽  
Author(s):  
Wang Qing-li ◽  
Kuan Peng ◽  
Guo Yi-Huan ◽  
Shao Yong-bo

Abstract In order to study the hysteretic behavior of concrete filled square CFRP steel tubular Beam-Column under different influence factors, 12 specimens were designed, and the failure mode, middle section lateral force-deflection(P-Δ) curve, middle section bending moment-curvature(M-φ) curve and middle section deflection-deformation(Δ−Δ') curve were studied. Axial compression ratio and longitudinal CFRP reinforcement coefficient as influencing factors, the effects of axial compression ratio and longitudinal CFRP reinforcement coefficient on P-Δ skeleton curve, M-φ skeleton curve, strength and stiffness degradation, ductility, cumulative energy consumption and other indexes were studied; the P-Δ curve and deformation mode of the specimens were simulated by ABAQUS, and the effects of axial compression ratio, slenderness ratio and other main parameters on the hysteretic performance of the members were studied. The test results show that CFRP has good lateral restraint and longitudinal reinforcement effect on CFST, and the local buckling of CFST is delayed. The P-Δ curve and M-φ curve of all specimens are full. In addition, the steel tube and CFRP have good synergy in both longitudinal and transverse directions. The change of axial compression ratio and longitudinal CFRP reinforcement coefficient has no significant effect on the strength degradation. The increase of axial compression ratio and longitudinal CFRP reinforcement coefficient can improve the flexural capacity and stiffness of the specimens, and slow down the stiffness degradation, but reduce the ductility and cumulative energy consumption of the specimens. The finite element software ABAQUS is used to simulate the P-Δ curve and deformation mode of specimens. It is found that the simulation results are in good agreement with the experimental results. Based on the model analysis of the main parameters, it is found that the increase of steel yield strength and CFRP layers can improve the bearing capacity of the specimens, and the axial compression ratio has the most significant effect on the specimens.


2021 ◽  
Vol 11 (21) ◽  
pp. 10407
Author(s):  
Man Xu ◽  
Yiran Jiang ◽  
Xingfu He ◽  
Juntong Yuan ◽  
Ying Gao

Purpose: To provide some suggestions on how to effectively master these movements during training. Methods: The dynamics method and ABAQUS simulation analysis were used to analyze the two technical movements of the three-section cudgels: wrestling cudgels and retrieving cudgels. Results: In the process of wrestling the cudgel, the best effect is achieved when the height of the cudgel holding hand is between 70 cm and 80 cm from the ground. The maximum height of the rebound was very similar with different initial angular velocities, at 4.5–9 cm. The initial angular velocities caused significant impact to the horizontal movement of cudgel at 8 s. By excluding the errors, the horizontal movement of cudgel increased approximately linearly with the increase of the initial angular velocity. Conclusions: When the height between held cudgel and the ground was controlled at 1.5 times the height of the middle section, the rebound of the tail section was the least. When completing the movement of three-section cudgel, the cudgel body should be in the same plane perpendicular to the ground and to better retrieve the three-section cudgel. The main factor affecting the cudgel wrestling was the height between the cudgel holder and the ground.


2021 ◽  
Vol 2101 (1) ◽  
pp. 012021
Author(s):  
Rui Huang ◽  
Junming Cheng ◽  
Tian xia ◽  
Quanke Feng

Abstract In this paper, the piston clearance leakage model in reciprocating labyrinth compressor is established, and the leakage characteristics of labyrinth piston are analysed. The results show that in the labyrinth entrance section, the gas velocity decreases greatly, and the throttling effect is the most obvious. In the middle section of the labyrinth, the flow velocity descending gradient decreases. In the exit section, the flow rate begins to increase. When the labyrinth clearance is less than or equal to 0.1 mm, the clearance changes has little effect on the leakage. When the clearance is greater than 0.1 mm, the leakage increases rapidly with the clearance increasing. When the piston operates eccentrically, the leakage will increase by 1.5 ∼ 2 times compared with the non-eccentric operation. Therefore, the eccentric operation of the piston should be avoided as much as possible and the clearance should be reduced.


2021 ◽  
Author(s):  
Mohd Zarir Bin Musa ◽  
Jerry Tobing ◽  
Muhammad Ikhsan Akbar ◽  
Irshad Fajar ◽  
Wienarno Nurrakhmadi ◽  
...  

Abstract With the far-reaching reservoir target coupled with other surface constraint including fix well slot coordinate and pre-determined conductor size, the longest well with 2.5 ERD Index in Offshore East Java was pioneered. The team has big task in hand to ensure all aspect of ERD well engineering and construction are being addressed properly within the fast-paced time frame given. One of the approaches strategized by the team is to split the high angle big hole size long interval of middle section into two casing string which was not the common architecture applied in the other offset wells. The objective was to ensure that the middle section of the well will not be compromised and avoid complication in the deeper section of the well. Worth to mention that the middle section consists combination of challenging lithology that deserve the right solution to avoid unwanted problem. There are highly kartsitified carbonate formation, shale and sand interbedded formation, and thick time dependent shale formation. To mitigate the challenges previously mentioned, intermediate section which is normally drilled and isolated with 17-1/2" hole × 13-3/8" casing in previous wells, now separated into two sections which require enlargement: 17-1/2" to 20" and 14-3/4" to 17-1/2". This paper focuses on 14-3/4" × 17-1/2" which is the most challenging underreaming operation in this well and the first of its kind in this field application. Adding to the fact that the inclination reach 75 degree in this section, SOBM and RSS BHA are deployed to mitigate the torque and drag issue. State of the art modelling tool is also used by team to define effectively match BHA and drilling parameter with minimal lateral vibration and stick slip for this section Apart from drilling stage, the enlarged hole size requires a condition to have uncommon casing size and specification, 16" intermediate semi flush liner connection and 13-3/8" full flush intermediate casing connection to ensure sufficient annular area and less restriction during running to bottom. The relentless effort to secure one the most critical ERD well construction phase has really paid off by allowing the next phase of operation to be executed as per plan thus assuring the overall well objective is met.


2021 ◽  
Vol 865 (1) ◽  
pp. 012001
Author(s):  
Lingqi Li ◽  
Kai Wu ◽  
Huijuan Yin ◽  
Bo Qu ◽  
Liyong Jiang ◽  
...  

Author(s):  
Ернст Вагнер

The first part of this paper asks how European art education traditionally positions itself despite an ever-changing world, mainly in respect to the question how to teach cultural heritage. Focussing the history of art we can see that teaching the canon connected with development narratives is still dominant. But some trends can be observed that open the chance to further develop those traditions, e.g. focussing intercultural entanglements, transcultural understandings of ‘objects’ and including the issue of power. These trends try to provide answers to today's challenges. The inquiry finally leads to an analytical grid as a model to understand contemporary complexities in a better way. In the middle section, this is discussed in more detail using a concrete example, the political demands for the return of cultural heritage, the Benin bronzes that were stolen by British colonialists in Nigeria in the 19th century and are now mainly in European museums. It gets clear that the application of the model – developed in the first part – to this example reveals its limits, as unsolvable problems occur. The case study of the Benin bronzes triggers a set of new questions that are becoming increasingly important for art education – at least in Germany – but which have hardly been asked so far. Examples are: Who speaks? In which language? With whom? Who owns? Is negation a model for intercultural dialogue? Etcetera. In the last part, this set of questions is posed to a concrete international project with partners in Cameroon, Ghana, Kenya and South Africa that the author is co-ordinating at the Art of Fine Academy in Munich. The set of questions is used to critically explore this project in a way that could also be transferred to any other project in the field of art and cultural education in formal and non-formal settings.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Robert F. Wittkamp

Abstract Some of Ōtomo no Yakamochi’s best-known poems are included among the fifteen poems that introduce the Man’yōshū Book 19. While research sees the common themes of these poems, it does not understand them as a cohesive group or “work” (sakuhin 作品). This essay takes a narratological approach and subjects the poems to a reinterpretation based on the two dimensions of “space” and “time.” This reading reveals the fifteen poems as a narrative sequence. For comparison and at the same time for a better understanding, a sequence from Book 17 is consulted, which shows similar narrative features. While the spatial aspects are in the foreground there, the sequence from the Book 19 deals with the theme of time. Both sequences are framed, and their middle section can be compared to the enlargement technique of photography (blow-up). In both sequences, the traditional banquet poetry to the 3rd day in the 3rd month plays a central role. The essay contains a complete translation of the fifteen poems from the Book 19.


Quaternary ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 29
Author(s):  
Nurcan Avşin ◽  
Mehmet Korhan Erturaç ◽  
Eren Şahiner ◽  
Tuncer Demir

The paper describes climatic and tectonic effects on fluvial processes of East Anatolia. This study from the Muş Basin contains three alluvial terrace levels (T3-T1) ranging from 30–35 m to 3–5 m above the present Murat River in its middle section. In order to provide a chronology for the evaluation of the significant, effects of climatic changes and tectonic uplift, we used optically stimulated luminescence (OSL) dating of the river deposits of the youngest (T3) and medium terrace (T2). The ages from these terrace deposits show that the T3 has formed approximately 6.5 ka ago, i.e., during the last part of the Holocene (MIS 1) and T2 has formed nearly 25 ka ago, i.e., during MIS 2 at the ending of the last glacial period. According to these results, it appears that the Murat River established its terrace sequences both in cold and warm periods. The variations in climate oriented fluvial evolution between the East Anatolia fluvial system and the temperate-periglacial fluvial systems in Europe may be the conclusion of different vegetation cover and melting thicker snow coverings in cold periods.


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