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Speech recognition algorithm based on neural network and hidden Markov model

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The Journal of China Universities of Posts and Telecommunications 2018年第2期25卷 28-37,102页

作者： Zhao Jianhui Gao Hongbo liu yuchao Cheng Bo Department of Computer Science and Technology Tsinghua University State Key Laboratory of Automotive Safety and Energy Tsinghua University Center for Intelligent Connected Vehicles and Transportation Tsinghua University

This study proposes a hybrid model of speech recognition parallel algorithm based on hidden Markov model( HMM) and artificial neural network( ANN). First,the algorithm uses HMM for time-series modeling of speech signals and calculates the voice to the HMM of the output probability score. Second,with the probability score as input to the neural network,the algorithm gets information for classification and recognition and makes a decision based on the hybrid model. Finally,Matlab software is used to train and test sample data. Simulation results show that using the strong time-series modeling ability of HMM and the classification features of the neural network,the proposed algorithm possesses stronger noise immunity than the traditional HMM. Moreover,the hybrid model corrects the individual flaws of the HMM and the neural network,and greatly improves the speed and performance of speech recognition.

关键词： speech recognition HMM neural network

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Relay navigation strategy study on intelligent drive on urban roads

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The Journal of China Universities of Posts and Telecommunications 2016年第2期23卷 79-90页

作者： Gao Hongbo Zhang Xinyu An Lifeng liu yuchao Li Deyi State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China Information Technology Center Tsinghua University Beijing 100083 China Department of Computer Science and Technology Tsinghua University Beijing 100083 China The 61th Institute of Electronic System Engineering Beijing 100039 China

In order to solve navigation problem of intelligent vehicle driving on urban roads and to achieve the navigation in intersection area, intersection transition area and section area. The relay navigation strategy and algorithm can solve the navigation problem of intelligent vehicle driving in typical urban roads such as intersection area, intersection transition area and section area, realizing seamless handover among different typical areas. Bezier curve function model was introduced to different typical areas, which solved the self-adaption recognition problem in different typical areas and revised positional accuracy with the help of cloud computing positioning service. In order to explain the strategy implement, an instance based on the strategy was adopted. Instance analysis indicates that as for the navigation problem in intersection area, intersection transition area and section area, if the relay navigation strategy is utilized, the self-adaption recognition problem in different typical areas can be handled. Based on the relay navigation strategy, the drive of intelligent vehicle on urban roads can effectively solve the self-adaption recognition problem in different typical areas in urban and further solve driving problems of intelligent vehicle of the same category in urban roads.

关键词： intelligent vehicle intelligent drive urban roads relay navigation strategy

Cu_2ZnSn(SSe)_4薄膜的制备及其性能研究

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功能材料 2019年第5期50卷 5106-5109,5115页

作者：侯冠宇刘玉超中国人民解放军空军勤务学院江苏徐州221000

通过不同液相前驱体合成了Cu_2ZnSn(SSe)_4(CZTSSe)薄膜,采用XRD、SEM等手段进行表征,结果表明,前驱体中Zn源的活性直接影响到最终生成CZTSSe晶体材料的性能;通过肼、S粉和Zn粉提供的Zn源不容易形成晶核,发生反应所需反应温度较高,但是... 详细信息

通过不同液相前驱体合成了Cu_2ZnSn(SSe)_4(CZTSSe)薄膜,采用XRD、SEM等手段进行表征,结果表明,前驱体中Zn源的活性直接影响到最终生成CZTSSe晶体材料的性能;通过肼、S粉和Zn粉提供的Zn源不容易形成晶核,发生反应所需反应温度较高,但是容易形成大的晶型,制备的CZTSSe晶体能量转化率为6.21%;而通过干冰、N_2H_4和Zn粉提供的Zn源容易形成晶核,但其后续晶体长大的反应进行比较困难,不容易形成大的晶型,制备的CZTSSe晶体能量转化率只有5.50%。揭示了不同Zn前驱体对CZTSSe薄膜结构、晶体尺寸以及转化率的影响,并对机理进行了初步探讨。

关键词：太阳能电池铜锌锡硫硒 CZTSSe 前驱体活性

Constructing an efficient deep-blue TADF emitter by host-guest interactions towards solution-processed OLEDs with narrowband emission

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Science China Chemistry 2023年第3期66卷 826-836页

作者： Yanchao Xie Lei Hua Zhi Wang Yuerong liu Shian Ying yuchao liu Zhongjie Ren Shouke Yan Department Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-PlasticsSchool of Polymer Science and EngineeringQingdao University of Science&TechnologyQingdao 266042China State Key Laboratory of Chemical Resource Engineering College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China

High-efficiency thermally activated delayed fluorescence(TADF) emitters and corresponding well-designed solution-processed organic light emitting diodes(OLEDs) are presently attractive due to their potential for exploiting large-area flexible displays. In this context, we innovatively integrate 2,12-di-tert-butyl-5,9-dioxa-13b-boronaphtho [3,2,1] anthracene as the acceptor with 3,6-bis(3,6-di-tert-butylcarbazol-N-yl) carbazole as the donor to construct a rigid deep-blue emitter, TB-3t BuCz, which exhibits a narrow emission with full-width-at-half-maximum(FWHM) of 46 nm. TB-3t BuCz itself dispalys no TADF characteristics both in solution or in pure film states. However, the significant TADF behavior can be observed when TB-3t BuCz is doped with 2,6-DCzPPy host due to the formation of exciplex-like species in 2,6-DCzPPy/TB-3t BuCz system. It is also found that the discernible spin-flip of triplet excitons is feasible when the S1/T1states of the formed exciplex stay slightly lower than S1 and T1states of TB-3t BuCz for the other host/TB-3t BuCz systems. Eventually, thanks to the synergetic effect of rigid structure and favorable photophysical properties of TB-3t BuCz, the solution-processed OLEDs based on 2,6-DCzPPy/TB-3t BuCz as emitting layer has achieved the significantly improved external quantum efficiency(EQE) of 14.6% with suppressed efficiency *** CIE1931 coordinate of(0.158, 0.052) is typically in deep-blue region. Note that, this EQE value is among the highest echelon of solution-processed OLEDs with deep-blue emission by utilizing boron-containing TADF emitters.

关键词： thermally activated delayed fluorescence oxygen-bridged cyclized boron host-guest interactions solution-processed OLEDs narrowband deep-blue emission

Correlation between lower gastrointestinal tract symptoms and quality of life in patients with stable chronic obstructive pulmonary disease

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Journal of Traditional Chinese Medicine 2013年第5期33卷 608-614页

作者： Yan Sun Fengjie Zheng Yuhang Li Ruohan Wu yuchao liu Miao liu Jinchao Zhang Kuo Gao School of Preclinical Medicine Beijing University of Chinese Medicine

OBJECTIVE:To explore correlations between the symptoms of constipation and abdominal distention and severity of chronic obstructive pulmonary disease(COPD)in patients with stable ***:We studied 191 patients with stable COPD(according to defined criteria)in this cross-sectional study from four three-level class A Chinese medicine hospitals in *** built an Epidata 3.0 database and performed statistical analysis with SPSS,version *** analyzed correlations between the frequency of lower gastrointestinal tract symptoms(constipation and abdominal distention)and scores for major pulmonary symptoms(cough,sputum and wheezing)based on the ***'s Respiratory Questionnaire(SGRQ),6-minute walking distance(6MWD)and frequency of acute exacerbations of COPD(AECOPD).RESULTS:In addition to their pulmonary symptoms,39.79%and 40.31%of study patients withstable COPD reported constipation and abdominal distention,*** for major pulmonary symptoms(cough,sputum and wheezing),AECOPD and SGRQ values in patients with constipation and abdominal distention were significantly greater,and the 6MWD markedly shorter,than in those without *** to Pearson's correlation analysis,there were strong correlations between these lower gastrointestinal tract symptoms and scores for pulmonary symptoms,SGRQ,6MWD and ***:Lower gastrointestinal tract symptoms such as constipation and abdominal distention can adversely affect pulmonary symptoms,frequency of acute exacerbations and quality of life in patients with stable COPD.

关键词： Chronic obstructive pulmonary disease Constipation Flatulence Quality of life Questionnaires

Emerging trends in the selective production of value-added aromatics

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Science China Chemistry 2025年第1期68卷 15-20页

作者： yuchao Wu Houliang Dai Weisheng Yang Yaxing Li Lichen liu Petrochemical Research Institute Company Limited China National Petroleum Corporation Engineering Research Center of Advanced Rare Earth Materials Department of Chemistry Tsinghua University

1 Introduction Aromatics (mainly benzene, toluene, and xylenes, BTX) are essential intermediates in the chemical industry. They are employed in the synthesis of a broad spectrum of chemicals and materials, e.g., various polymers, plastics, resins, solvents, dyes, pharmaceuticals [1]. The manufacturing pathway of BTX mainly includes petroleum reforming of naphtha, coal-to-aromatics, methanol-to-aromatics [2].

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Realizing External Quantum Efficiency over 25% with Low Efficiency Roll-Off in Polymer-Based Light-Emitting Diodes Synergistically Utilizing Intramolecular Sensitization and Bipolar Thermally Activated Delayed Fluorescence Monomer

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CCS Chemistry 2023年第4期5卷 1005-1017页

作者： yuchao liu Yanchao Xie Lei Hua Xingwen Tong Shian Ying Zhongjie Ren Shouke Yan Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-PlasticsQingdao University of Science and TechnologyQingdao 266042 State Key Laboratory of Chemical Resource Engineering College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029

Since polymer-based light-emitting diodes(PLEDs)arewellsuited building blocks for large-area and low-cost flexible display equipment,state-of-the-art thermally activated delayed fluorescence(TADF)PLEDs are in high *** respond to this demand,light-emitting TADF units have initially been modified with electron-transporting units to balance the carrier transport of regiorandom TADF polymers,and simultaneously,an intramolecular sensitizing strategy has also been employed by covalently incorporating TADF sensitizers with light-emitting TADF units and hosts in conjugated polymers to accelerate the spin-flip of triplet *** photophysical properties have been achieved by a rational regulation of the proportions of each component,achieving a photoluminescence quantumyield of 90%,an extremely high rate of reverse intersystem crossing of 3×106 s−1,and a relatively low nonradiative decay rate of around 105 s−*** a result,the solutionprocessed PLEDs can attain an external quantum efficiency(EQE)value of 25.4%with emission peaks of around 550 nm,representing record-high performance for *** efficiency roll-off can also be significantly suppressed,maintaining an EQE value of 24.2%at 1000 cd/m2 with ideal efficiency roll-off of lower than 5%.Encouragingly,this work provides a valid strategy to tackle the imperative need for PLEDs with high EQE and low efficiency roll-off.

关键词： thermally activated delayed fluorescence polymer light-emitting diodes intramolecular sensitizing strategy balanced carrier transports low efficiency roll-off

Review on herbal tea as a functional food:classification,active compounds,biological activity,and industrial status

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Journal of Future Foods 2023年第3期3卷 206-219页

作者： yuchao liu Chunyan Guo Erhuan Zang Ruyu Shi Qian liu Min Zhang Keyong Zhang Minhui Li Qiqihar Medical University Qiqihar 161006China Baotou Medical College Baotou 014040China Inner Mongolia Autonomous Region Hospital of Traditional Chinese Medicine Hohhot 010020China Inner Mongolia Key Laboratory of Characteristic Geoherbs Resources Protection and Utilization Baotou 014040China

Most herbal tea infusions use edible medicinal plants as raw material and are consumed *** herbal tea has a long history of health care applications worldwide,there is a lack of systematic research on the classification and functional nutritional value of various herbal *** recent years,the discovery of the rich biological activities and health benefits of herbal tea has become a driving force for researchers interested in its development as a functional ***,the shortcomings of herbal tea products are not fully *** particular,the quality evaluation system is not perfect,and there is insufficient data on the mechanism of action of herbal teas in their traditional *** better understand the functions and mechanisms of various herbal teas,this article reviews the classification,effective chemical composition,main biological activities,and mechanism of action of herbal ***,the current advantages,limitations,and direction of future development of herbal tea are determined and discussed.

关键词： Herbal tea Functional food products Natural active ingredients Biological activities Industrial status

Bipolar Thermally Activated Delayed Fluorescence Emitter with Balanced Carrier Transport for High-Efficiency Nondoped Green Electroluminescent Devices

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CCS Chemistry 2024年第9期6卷 2346-2357页

作者： yuchao liu Zhagen Miao Haikuo Gao Shian Ying Can Gao Shouke Yan Huanli Dong Zhongjie Ren Key Laboratory of Rubber-Plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-PlasticsSchool of Polymer Science and EngineeringQingdao University of Science and TechnologyQingdao 266042 National Laboratory for Molecular Sciences Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190 Department of Chemistry University of Chinese Academy of SciencesBeijing 100049 Shandong Engineering Research Center of Aeronautical Materials and Devices College of Aeronautical EngineeringBinzhou UniversityBinzhou 251900 State Key Laboratory of Chemical Resource Engineering College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029

High-efficiency electroluminescent devices featuring simplified architecture have received considerable attention due to significant advantages in construction procedures and commercialized ***,there still remains a critical challenge with regard to the lack of organic semiconductors that simultaneously possess high luminescent efficiency and balanced carrier-transporting ***,we design a thermally activated delayed fluorescence(TADF)emitter 4-(9,9-dimethyl-9,10-dihydroacridine)-4′-triphenylphosphineoxide-benzophenone(DMAC-BPTPO)by incorporating triphenylphosphine oxide into the donor–acceptor *** accessional electrontransporting moiety,rod-like dimer,and horizontally packing model synergistically enable DMAC-BP-TPO which possesses an excellent photoluminescence quantum yield of nearly 90%with a reverse intersystem crossing rate constant of 2.0×106 s−1,horizontal dipole ratio of 89%,and a balanced electron and hole mobilities with a small constrast ratio of ***,simplified electroluminescent devices including organic lightemitting diodes(OLEDs)and organic light-emitting transistors(OLETs)incorporating DMAC-BP-TPO-based nondoped film are demonstrated due to their superior integrated optoelectronic properties along with preferable horizontal dipole orientation.A record-high external quantum efficiency value of 21.7%and 4.4%are finally achieved in the simplified nondoped OLED and OLET devices,which are among the highest values in the related research *** work provides a new avenue to develop a high-efficiency bipolar TADF emitter to advance the simplified electroluminescent devices.

关键词： organic light-emitting diode organic lightemitting transistor bipolar thermally activated delayed fluorescence nondoped active layer