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Predictability of the upper ocean heat content in a Community Earth System Model ensemble prediction system

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Acta Oceanologica Sinica 2024年第1期43卷 1-10页

作者： ting liu Wenxiu Zhong State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai 519082China

Upper ocean heat content(OHC)has been widely recognized as a crucial precursor to high-impact climate variability,especially for that being indispensable to the long-term memory of the *** the predictability of OHC using state-of-the-art climate models is invaluable for improving and advancing climate *** developed retrospective forecast experiments,based on a Community Earth System Model ensemble prediction system,offer a great opportunity to comprehensively explore OHC *** results indicate that the skill of actual OHC predictions varies across different oceans and diminishes as the lead time of prediction *** spatial distribution of the actual prediction skill closely resembles the corresponding persistence skill,indicating that the persistence of OHC serves as the primary predictive signal for its *** decline in actual prediction skill is more pronounced in the Indian and Atlantic oceans than in the Pacific Ocean,particularly within tropical ***,notable seasonal variations in the actual prediction skills across different oceans align well with the phase-locking features of OHC *** potential predictability of OHC generally surpasses the actual prediction skill at all lead times,highlighting significant room for improvement in current OHC predictions,especially for the North Indian Ocean and the Atlantic *** such improvements necessitates a collaborative effort to enhance the quality of ocean observations,develop effective data assimilation methods,and reduce model bias.

关键词： ocean heat content prediction skill retrospective forecast experiment

Research on Voiceprint Recognition of Camouflage Voice Based on Deep Belief Network

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International Journal of Automation and computing 2021年第6期18卷 947-962页

作者： Nan Jiang ting liu College of Public Security Information Technology and Intelligence Criminal Investigation Police University of ChinaShenyang 110854China College of Light Industry Liaoning UniversityShenyang 110036China

The problem of disguised voice recognition based on deep belief networks is studied. A hybrid feature extraction algorithm based on formants, Gammatone frequency cepstrum coefficients(GFCC) and their different coefficients is proposed to extract more discriminative speaker features from the original voice data. Using mixed features as the input of the model, a masquerade voice library is constructed. A masquerade voice recognition model based on a depth belief network is proposed. A dropout strategy is introduced to prevent overfitting, which effectively solves the problems of traditional Gaussian mixture models, such as insufficient modeling ability and low discrimination. Experimental results show that the proposed disguised voice recognition method can better fit the feature distribution, and significantly improve the classification effect and recognition rate.

关键词： Disguised voice recognition deep belief network feature extraction Gammatone frequency cepstrum coefficients(GFCC) dropout

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Annealing Effects on Structural,Optical Properties and Laser-Induced Damage Threshold of MgF2 Thin Films

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Acta Metallurgica Sinica(English Letters) 2017年第1期30卷 73-78页

作者： ting-ting Tan Bang-Jie liu Zhi-Hui Wu Zheng-Tang liu State Key Lab of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China

The chemical structures, optical properties and laser-induced damage thresholds of magnesium fluoride films annealed at different temperatures were investigated. The results showed that the stoichiometry of MgF2 film changed a little with the increase in annealing temperature. Analysis of the optical properties indicated that excellent antireflection behavior of the film in the range of 200-400 nm can be obtained by the samples coated with MgF2 film. The refractive index increased and the extinction coefficient decreased with increasing annealing temperature. Compared with the asdeposited films, the laser-induced damage threshold was improved after annealing process and decreased with the increase in annealing temperature, which was probably due to the denser film and more absorption centers under higher annealing temperature.

关键词： Annealing temperature Chemical structure Optical properties Laser-induced damage threshold (LIDT) MgF2 films

Zero-inflated non-central negative binomial distribution

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Applied Mathematics(A Journal of Chinese Universities) 2022年第2期37卷 187-198页

作者： TIAN Wei-zhong liu ting-ting YANG Yao-ting College of Big Data and Internet Shenzhen Technology UniversityShenzhen 518118China School of Science Xi'an University of TechnologyXi'an 710054China

In this article, the zero-inflated non-central negative binomial(ZINNB) distribution is introduced. Some of its basic properties are obtained. In addition, we use the maximum likelihood estimation method to estimate t... 详细信息

关键词： zero-in ated non-central negative binomial distribution maximum likelihood estimation good-ness of fit

Nanoscale Reciprocating Sliding Contacts of Textured Surfaces:Influence of Structure Parameters and Indentation Depth

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Chinese Journal of Mechanical Engineering 2018年第4期31卷 168-181页

作者： Rui-ting Tong Geng liu Shaanxi Engineering Laboratory for Transmissions and Controls Northwestern Polytechnical University

Textured surfaces are widely used in engineering components as they can improve tribological properties of sliding contacts, while the detailed behaviors of nanoscale reciprocating sliding contacts of textured surfaces are still lack of study. By using multiscale method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. The influence of indentation depth, texture shape, texture spacing, and tip radius on the average friction forces and the running-in stages is studied. The results show that the lowest indentation depth can make all the four textured surfaces reach steady state. Surfaces with right-angled trapezoid textures on the right side are better for reducing the running-in stage, and surfaces with right-angled trapezoid textures on the left side are better to reduce wear. Compared with other textured surfaces, the total average friction forces can be reduced by 82.94%–91.49% for the case of the contact between the tip with radius R = 60rand the isosceles trapezoid textured surface. Besides,the total average friction forces increase with the tip radii due to that bigger tip will induce higher contact areas. This research proposes a detailed study on nanoscale reciprocating sliding contacts of textured surfaces, to contribute to design textured surfaces, reduce friction and wear.

关键词： Nanoscale Reciprocating sliding contacts Textured surface Structure parameters Indentation depth

A survey of discourse parsing

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Frontiers of Computer Science 2022年第5期16卷 85-96页

作者： Jiaqi LI Ming liu Bing QIN ting liu School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China Peng Cheng Laboratory Shenzhen 518052China

Discourse parsing is an important research area in natural language processing(NLP),which aims to parse the discourse structure of coherent *** this survey,we introduce several different kinds of discourse parsing tasks,mainly including RST-style discourse parsing,PDTB-style discourse parsing,and discourse parsing for multiparty *** these tasks,we introduce the classical and recent existing methods,especially neural network *** that,we describe the applications of discourse parsing for other NLP tasks,such as machine reading comprehension and sentiment ***,we discuss the future trends of the task.

关键词： discourse parsing discourse structure RST PDTB STAC

Bidirectional Transformer with absolute-position aware relative position encoding for encoding sentences

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Frontiers of Computer Science 2023年第1期17卷 63-71页

作者： Le QI Yu ZHANG ting liu School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China

Transformers have been widely studied in many natural language processing (NLP) tasks, which can capture the dependency from the whole sentence with a high parallelizability thanks to the multi-head attention and the position-wise feed-forward network. However, the above two components of transformers are position-independent, which causes transformers to be weak in modeling sentence structures. Existing studies commonly utilized positional encoding or mask strategies for capturing the structural information of sentences. In this paper, we aim at strengthening the ability of transformers on modeling the linear structure of sentences from three aspects, containing the absolute position of tokens, the relative distance, and the direction between tokens. We propose a novel bidirectional Transformer with absolute-position aware relative position encoding (BiAR-Transformer) that combines the positional encoding and the mask strategy together. We model the relative distance between tokens along with the absolute position of tokens by a novel absolute-position aware relative position encoding. Meanwhile, we apply a bidirectional mask strategy for modeling the direction between tokens. Experimental results on the natural language inference, paraphrase identification, sentiment classification and machine translation tasks show that BiAR-Transformer achieves superior performance than other strong baselines.

关键词： Transformer relative position encoding bidirectional mask strategy sentence encoder

Multi-objective optimization of equipment capacity and heating network design for a centralized solar district heating system

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Building Simulation 2023年第1期16卷 51-67页

作者： Yanfeng liu ting Mu Xi Luo School of Building Services Science and Engineering Xi'an University of Architecture and TechnologyXi'an 710055China State Key Laboratory of Green Building in Western China Xi'an 710055China

Northwest China has abundant solar energy resources and a large demand for winter *** solar energy for centralized heating is a clean and effective way to solve local heating *** present studies usually decoupled solar heating stations and the heating network in the optimization design of centralized solar heating systems,this study developed a joint multi-objective optimization model for the equipment capacity and the diameters of the heating network pipes of a centralized solar district heating system,using minimum total life cycle cost and CO_(2)emission of the system as the optimization *** typical cities in northwest China with different solar resource conditions(Lhasa,Xining,and Xi'an)were selected as cases for *** to the results,the solar heating system designed using the method proposed in this study presents lower economic cost and higher environmental protection in comparison to separately optimizing the design of the solar heating station and the heating ***,the solar fraction of the optimal systems are 90%,70%,and 31%for Lhasa,Xining,and Xi'an,and the minimum water supply temperatures are 55℃,50℃,and 65℃for an optimal economy and 55℃,45℃,and 45℃for optimal environmental protection,*** was also established that the solar collector price has a greater impact on the equipment capacity of the solar heating station than the gas boiler price.

关键词： solar energy solar energy system district heating optimization design genetic algorithm

Multi-resolution technique integrated with smoothed particle element method (SPEM) for modeling fluid-structure interaction problems with free surfaces

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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 41-62页

作者： ting Long Zhilang Zhang Moubin liu Beijing Innovation Center for Engineering Science and Advanced Technology(BIC-ESAT) College of EngineeringPeking UniversityBeijing 100871China State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering SciencePeking UniversityBeijing 100871China Institute of Ocean Research Peking UniversityBeijing 100871China School of Mechanical Engineering Guangxi UniversityNanning 530004China

Free-surface flows, especially those associated with fluid-structure interactions(FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed particle element method(SPEM) to simulate FSIs. In this method, both the fluid and solid regions are initially modeled using a smoothed finite element method(S-FEM) in a Lagrangian frame, whereas the fluid regions undergoing large deformations are adaptively converted into particles and modeled with an improved smoothed particle hydrodynamics(SPH) method. This approach greatly improves computational accuracy and efficiency because of the advantages of the S-FEM in efficiently treating solid/fluid regions showing small deformations and the SPH method in effectively modeling moving interfaces. In this work, we further enhance the efficiency of the SPEM while effectively capturing local fluid information by introducing a multi-resolution technique to the SPEM and developing an effective approach to treat multi-resolution element-particle interfaces. Various numerical examples demonstrate that the multiresolution SPEM can significantly reduce the computational cost relative to the original version with a constant ***, the novel approach is effective in modeling various incompressible flow problems involving FSIs.

关键词： smoothed particle element method(SPEM) smoothed finite element method(S-FEM) smoothed particle hydrodynamics(SPH) multi-resolution technique fluid-structure interaction