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Development of endemicity and conservation importance indices for tropical forests and the floral diversity assessment of *** in Benguet,Philippines

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Journal of Mountain Science 2024年第3期21卷 786-804页

作者： Johndale Rein T.BULLONG Jim P.SILVERIO Joanna I.ALAFAG Maricel A.GURON Jones T.NAPALDET Department of Environmental Science Benguet State UniversityLa Trinidad 2601Philippines Department of Biology Benguet State UniversityLa Trinidad 2601Philippines

The scientific community faces the challenge of measuring progress toward biodiversity targets and indices have been traditionally ***,recent inventories in secondary tropical mountain forests using traditional biodiversity indices have yielded results that are indistinct with primary *** shows the need to develop complementary indices that goes beyond species count but integrates the distribution and conservation status of the *** study developed endemicity and conservation importance index for tropical forest that incorporated the distribution and conservation status of the *** indices were applied to ***,a remnant primary mossy forest in Buguias,Benguet,Philippines,that resulted to endemicity index of 81.07 and conservation importance index of *** these with secondary forest sites with comparable Shannon-Wiener,Simpson,Evenness and Margalef’s indices,our endemicity and conservation indices clearly differentiates primary forest(our study site)with higher values from secondary forests with much lower ***,we are proposing these indices for a direct but scientifically-informed identification of specific sites for conservation and protection in tropical ***,our study documented a total of 168 vascular plant species(79 endemic and 12 locally threatened species)in *** are of tropical elements for both generic and species levels with some temperate elements that could be attributed to the site's high elevation and semi-temperate *** are important baseline information for conservation plans and monitoring of tropical mossy forests.

关键词： Endemicity index Conservation importance index Cordillera Central Range Floristic element Jaccard Index of Similarity

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Capacitor Voltage Imbalance Mechanism and Balancing Control of MMC When Riding Through PTG Fault

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 778-785页

作者： Zhen He Maozeng Lu Lijun Hang Pingliang Zeng Yanhua Liu Hangzhou Dianzi university Hangzhou 310018China Shandong university of Technology Zibo 255000China state Grid Hangzhou Power Supply Company State GridHangzhou 310000China

Modular multilevel converter (MMC) based fault ride through (FRT) control is a promising solution to deal with the pole-to-ground (PTG) fault in high voltage direct current (HVDC) system. However, when MMC switches to the FRT control, capacitor voltage imbalance between upper and lower arms will occur, resulting in the deterioration of FRT performance. This letter provides a comprehensive analysis for the imbalance issue from the perspective of fundamental frequency circulating current (FFCC). It is found the imbalance during FRT stage will not expand continuously, but converge to a certain value gradually. The specific imbalance degree is closely associated with the amplitude of FFCC. In order to solve the imbalance issue, an open-loop balancing control is proposed. By introducing a fundamental frequency feedforward item to the inherent circulating current control, the proposed method can not only balance the capacitor voltages, but also minimize the amplitude of FFCC, and consequently the power loss of MMC during FRT process can be reduced. Finally, simulation results of PSCAD/ EMTDC verify the validity of theoretical analysis.

关键词： Balancing control capacitor voltage imbalance FFCC FRT control HVDC system PTG fault

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Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes

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Chinese Physics C 2024年第4期48卷 95-106页

作者： S.V.Sidorov A.S.Kornilova T.Yu.Tretyakova Faculty of Physics Lomonosov Moscow State UniversityMoscow 119991Russia Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State UniversityMoscow 119991Russia

The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this *** forces are considered within the framework of the Hartree-Fock approach with the Skyrme *** addition of a tensor component of interaction is shown to improve the description of the splittings between different single-particle states and decrease nucleon-nucleon pairing correlations in silicon and nickel *** attention was directed toward the role of isovector tensor forces relevant to the interaction of like nucleons.

关键词： nuclear shell model tensor interaction silicon isotopes nickel isotopes

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Detection of internal crack growth in polyethylene pipe using guided wave ultrasonic testing

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 319-329页

作者： Jay Kumar Shah Hao Wang Said El-Hawwat Centre of Advanced Infrastructure and Transportation RutgersThe State University of New JerseyNJ 08854USA Department of Civil and Environmental Engineering RutgersThe State University of New JerseyNJ 08854USA

Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes,its application on polyethylene(PE)pipe remains relatively *** growth of internal cracks in PE pipe severely affects its pressure-holding capacity,hence the early detection of internal cracks is crucial for effective pipeline maintenance *** study extends the scope of guided wave-based ultrasonic testing to detect the growth of internal cracks in a natural gas distribution PE *** experiments and a finite element model were planned to study the wave-crack interaction at different stages of axially oriented internal crack growth with a piezoceramic transducer-based setup arranged in a pitch-catch *** dispersion analysis supplemented with preliminary experiments was performed to isolate the optimal inspection frequency,leading to the selection of the T(0,1)mode at 50-kHz for the investigation.A transmission index based on the energy of the T(0,1)mode was developed to trace the extent of simulated crack *** findings revealed an inverse linear correlation between the transmission index and the crack depth for crack growth beyond 20%crack depth.

关键词： polyethylene pipes internal cracks guided wave ultrasonic testing torsional modes finite element modeling

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Highlights in recent wireless power IC research

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Journal of Semiconductors 2024年第4期45卷 5-7页

作者： Cheng Huang Junyao Tang Iowa state university AmesIowa50011USA

Wireless power transfer(WPT)has been a popular topic in power integrated circuit(IC)designs in the past *** slogan"cutting the last wire"presented in ISSCC’15[1],WPT is poised to take over many wired power deliveries applica-tions today,just like what happened to wireless communica-tion *** the years,WPT has become more mature and more wirelessly charged or powered products have become available on the *** mini review intends to summarize recent breakthroughs in WPT inte-grated circuits(IC)research.

关键词： WPT power wireless

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SeeMore: a spatiotemporal predictive model with bidirectional distillation and level-specific meta-adaptation

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Science China(Information Sciences) 2024年第8期67卷 147-171页

作者： Yuqing MA Wei LIU Yajun GAO Yang YUAN Shihao BAI Haotong QIN Xianglong LIU state Key Lab of Software Development Environment Beihang University

Predicting future frames using historical spatiotemporal data sequences is challenging and critical, and it is receiving a lot of attention these days from academic and industrial scholars. Most spatiotemporal predictive algorithms ignore the valuable backward reasoning ability and the disparate learning complexities among different layers and hence, cannot build good long-term dependencies and spatial correlations,resulting in suboptimal solutions. To address the aforementioned issues, we propose a two-stage coarse-to-fine spatiotemporal predictive model with bidirectional distillation and level-specific meta-adaptation(See More)in this paper, which includes a bidirectional distillation network(BDN) and a level-specific meta-adapter(LMA), to gain bidirectional multilevel reasoning. In the first stage, BDN concentrates on bidirectional dynamics modeling and coarsely constructs spatial correlations of different layers, while LMA is introduced in the second fine-tuning stage to refine the multilevel spatial correlations from a meta-learning *** particular, BDN mimics the forward and backward reasoning abilities of humans in a distillation manner,which aids in the development of long-term dependencies. The LMA views learning of different layers as disparate but related tasks and guides the transfer of learning experiences among these tasks through learning complexities. Thus, each layer could be closer to its solutions and could extract more informative spatial correlations. By capturing the enhanced short-term spatial correlations and long-term temporal dependencies,the proposed model could extract adequate knowledge from sequential historical observations and accurately predict future frames whose backtracking preconditions are consistent with the historical sequence. Our work is general and robust enough to be integrated into most spatiotemporal predictive models without requiring additional computation or memory cost during inference. Extensive experimen

关键词： spatiotemporal predictive learning knowledge transfer bidirectional distillation network level-specific meta-adapter coarse-to-fine training

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Demonstration of a small‐scale power generator using supercritical CO_(2)

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Carbon Energy 2024年第4期6卷 269-290页

作者： Ligeng Li Hua Tian Xin Lin Xianyu Zeng Yurong Wang Weilin Zhuge Lingfeng Shi Xuan Wang Xingyu Liang Gequn Shu state Key Laboratory of Engines Tianjin UniversityTianjinChina Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefeiChina state Key Laboratory of Automotive Safety and Energy Tsinghua UniversityBeijingChina

The supercritical CO_(2)(sCO_(2))power cycle could improve efficiencies for a wide range of thermal power *** sCO_(2)turbine generator plays an important role in the sCO_(2)power cycle by directly converting thermal energy into mechanical work and electric *** operation of the generator encounters challenges,including high temperature,high pressure,high rotational speed,and other engineering problems,such as *** studies of sCO_(2)turbines are insufficient because of the significant difficulties in turbine manufacturing and system *** most experimental investigations that primarily focus on 100 kW‐or MW‐scale power generation systems,we consider,for the first time,a small‐scale power generator using sCO_(2).A partial admission axial turbine was designed and manufactured with a rated rotational speed of 40,000 rpm,and a CO_(2)transcritical power cycle test loop was constructed to validate the performance of our manufactured generator.A resistant gas was proposed in the constructed turbine expander to solve the leakage *** dynamic and steady performances were *** results indicated that a peak electric power of 11.55 kW was achieved at 29,369 *** maximum total efficiency of the turbo‐generator was 58.98%,which was affected by both the turbine rotational speed and pressure ratio,according to the proposed performance map.

关键词： generator performance map power generation supercritical CO_(2) turbine

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Oilfield analogy and productivity prediction based on machine learning: Field cases in PL oilfield, China

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Petroleum Science 2024年第4期21卷 2554-2570页

作者： Wen-Peng Bai Shi-Qing Cheng Xin-Yang Guo Yang Wang Qiao Guo Chao-Dong Tan state Key Laboratory of Petroleum Resources and Engineering China University of Petroleum (Beijing)

In the early time of oilfield development, insufficient production data and unclear understanding of oil production presented a challenge to reservoir engineers in devising effective development plans. To address this challenge, this study proposes a method using data mining technology to search for similar oil fields and predict well productivity. A query system of 135 analogy parameters is established based on geological and reservoir engineering research, and the weight values of these parameters are calculated using a data algorithm to establish an analogy system. The fuzzy matter-element algorithm is then used to calculate the similarity between oil fields, with fields having similarity greater than 70% identified as similar oil fields. Using similar oil fields as sample data, 8 important factors affecting well productivity are identified using the Pearson coefficient and mean decrease impurity（MDI） method. To establish productivity prediction models, linear regression（LR）, random forest regression（RF）, support vector regression（SVR）, backpropagation（BP）, extreme gradient boosting（XGBoost）, and light gradient boosting machine（Light GBM） algorithms are used. Their performance is evaluated using the coefficient of determination（R2）, explained variance score（EV）, mean squared error（MSE）, and mean absolute error（MAE） metrics. The Light GBM model is selected to predict the productivity of 30 wells in the PL field with an average error of only 6.31%, which significantly improves the accuracy of the productivity prediction and meets the application requirements in the field. Finally, a software platform integrating data query,oil field analogy, productivity prediction, and knowledge base is established to identify patterns in massive reservoir development data and provide valuable technical references for new reservoir development.

关键词： Data mining technique Analogy parameters Oilfield analogy Productivity prediction Software platform

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Design and Control of an Autonomous Bat-like Perching UAV

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Journal of Bionic Engineering 2024年第3期21卷 1253-1264页

作者： Long Bai Wei Wang Xiaohong Chen Yuanxi Sun state Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China

Perching allows small Unmanned Aerial Vehicles(UAVs)to maintain their altitude while significantly extending their flight duration and reducing ***,current research on flying habitats is poorly adapted to unstructured environments,and lacks autonomous capabilities,requiring ideal experimental environments and remote control by *** solve these problems,in this paper,we propose a bat-like UAV perching mechanism by investigating the bat upside-down perching method,which realizes double self-locking in the perching state using the ratchet and four-link dead point *** on this perching mechanism,this study proposes a control strategy for UAVs to track targets and accomplish flight perching autonomously by combining a binocular camera,single-point LiDAR,and pressure *** perching experiments were conducted for crossbar-type objects *** experimental results show that a multirotor UAV equipped with the perching mechanism and sensors can reliably achieve autonomous flight perching and re-flying off the target *** power consumption is reduced to 2.9%of the hovering state when perched on the target object.

关键词： Bio-inspired design Perching mechanism UAV Autonomous flight

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Mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hot-roll bonding

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1890-1899页

作者： Zongan Luo Xin Zhang Zhaosong Liu Hongyu Zhou Mingkun Wang Guangming Xie state Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir *** results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 ***-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into *** addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the *** process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.

关键词： 6061 Al alloy hot-roll bonding vacuum mechanical properties interfacial grain boundaries

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