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Model Predictive Path Planning of AGVs: Mixed Logical Dynamical Formulation and Distributed Coordination

IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS 2023年第7期24卷 6943-6954页

作者： Xin, Jianbin Wu, xuwen D'Ariano, Andrea Negenborn, Rudy zhang, Fangfang Zhengzhou Univ Sch Elect & Informat Engn Zhengzhou 450001 Peoples R China Roma Tre Univ Dept Civil Comp Sci & Aeronaut Technol Engn I-00146 Rome Italy Delft Univ Technol Dept Marine & Transport Technol NL-2628 CD Delft Netherlands

Most of the existing path planning methods of automated guided vehicles (AGVs) are static. This paper proposes a new methodology for the path planning of a fleet of AGVs to improve the flexibility, robustness, and scalability of the AGV system. We mathematically describe the transport process as a dynamical system using an ad hoc mixed logical dynamical (MLD) model. Based on our MLD model, model predictive control is proposed to determine the collision paths dynamically, and the corresponding optimization problem is formulated as 0-1 integer linear programming. An alternating direction method of multipliers (ADMM)-based decomposition technique is then developed to coordinate the AGVs and reduce the computational burden, aiming for real-time decisions. The proposed methodology is tested on industrial scenarios, and results from numerical experiments show that the proposed method can obtain high transport productivity of the multi-AGV system at a low computational burden and deal with uncertainties resulting from the industrial environment.

关键词： Path planning Planning Task analysis Robots Predictive models Mathematical models Robot kinematics Automated guided vehicles path planning model predictive control mixed logical dynamical model

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Optimizing Carbon Dioxide Injection for Methane Hydrate Development and Carbon Sequestration: A Long-Term Numerical Simulation Study

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ENERGY & FUELS 2024年第21期38卷 20629-20643页

作者： zhang, Zhaobin Li, Yuxuan Xu, Tao Li, Shouding Li, Xiao Lu, Cheng Qin, xuwen Chinese Acad Sci Key Lab Shale Gas & Geoengn Inst Geol & Geophys Beijing 100029 Peoples R China Chinese Acad Sci Inst Earth Sci Beijing 100049 Peoples R China Univ Chinese Acad Sci Coll Earth & Planetary Sci Beijing 100049 Peoples R China Minist Nat Resources China Geol Survey Oil & Gas Resources Survey Beijing 100083 Peoples R China Natl Engn Res Ctr Gas Hydrate Explorat & Dev Guangdong 510075 Peoples R China China Geol Survey China Aero Geophys Survey & Remote Sensing Ctr Nat Beijing 100083 Peoples R China

Although in theory, carbon dioxide replacement for methane hydrate development can simultaneously enhance methane production rates and achieve carbon sequestration, its feasibility under field conditions has not been thoroughly investigated. This study proposes a carbon dioxide injection and methane development replacement strategy using a multiwell injection and production system. A custom-developed hydrate simulator was used to model the replacement process and its long-term evolution over 100,000 years. The results indicate that for shallowly buried hydrate reservoirs in seafloor sediments, carbon dioxide injection can significantly enhance methane production rates. The resulting carbon dioxide hydrates remain stable after the reservoir temperature and pressure recover, which facilitating carbon sequestration. Analysis of reservoir conditions reveals that carbon dioxide replacement is less effective for deeply buried methane hydrate reservoirs. Additionally, shallower water depths and intact seal integrity are favorable for carbon dioxide replacement. To achieve optimal replacement, the carbon dioxide injection rate must be carefully controlled;both excessive injection rates and premature injection can lead to carbon dioxide breakthrough from the injection well to the production well. Overall, this study provides insights into the feasibility analysis, site selection, and operational optimization for carbon dioxide replacement in methane hydrate development and carbon sequestration.

关键词： Carbon sequestration

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Combined Separated Oscillatory Fields Technique 37

Combined Separated Oscillatory Fields Technique

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37th European Frequency and Time Forum, EFTF 2024

作者： Sun, Fuyu Li, Chao Hu, xuwen zhang, Shougang National Time Service Center Chinese Academy of Sciences Xi'an China Chinese Academy of Sciences Key Laboratory of Time Reference and Applications Xi'an China

ISBN: (纸本)9798350354270

Ramsey's method of separated oscillatory fields (SOFs) has been originally used in beam magnetic resonance apparatuses, which leads to the establishment of atomic definition of time interval and frequency. Since then, various versions of the SOFs technique have been widely used for precise measurement of different physical quantities. Here, we present an alternative method to generate atomic beam magnetic resonance signals by combining two Ramsey cavities with phase differences of 0 and 1t. It is found that the strength of the resonance signals generated using this combined SOFs technique is approximately twice that of the resonance signals produced by the conventional SOFs techniques. In addition to generating stronger resonance, the combined Ramsey method eliminates the Rabi background superimposed on the Ramsey interference pattern without increasing the Ramsey signal linewidth. Thus, this technique serves a promising tool for high-precision measurements. © 2024 IEEE.

关键词： Velocity measurement

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Selective and Coverage Multi-head Attention for Abstractive Summarization

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Journal of Physics: Conference Series 2020年第1期1453卷

作者： xuwen zhang Gongshen Liu School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 China

Although the Transformer model has outperformed traditional sequence-to-sequence model in a variety of natural language processing (NLP) tasks, it still suffers from semantic irrelevance and repetition for abstractive text summarization. The main reason is that the long text to be summarized is usually composed of multi-sentences and has much redundant information. To tackle this problem, we propose a selective and coverage multi-head attention framework based on the original Transformer. It contains a Convolutional Neural Network (CNN) selective gate, which combines n-gram features with whole semantic representation to obtain core information from the long input sentence. Besides, we use a coverage mechanism in the multi-head attention to keep track of the words which have been summarized. The evaluations on Chinese and English text summarization datasets both demonstrate that the proposed selective and coverage multi-head attention model outperforms the baseline models by 4.6 and 0.3 ROUGE-2 points respectively. And the analysis shows that the proposed model generates the summary with higher quality and less repetition.

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Intelligent optimization of cold radial forging process for 20CrMnTiH alloy based on GA-BP and performance analysis

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2024年第9-10期135卷 4281-4307页

作者： Xu, Wenxia Wang, Zhaohui Zhu, xuwen zhang, Bowen Zheng, Zecheng Lv, Mi Wang, Hongxia Wuhan Univ Sci & Technol Key Lab Met Equipment & Control Technol Minist Educ Wuhan 430081 Hubei Peoples R China Wuhan Univ Sci & Technol Hubei Key Lab Mech Transmiss & Mfg Engn Wuhan 430081 Hubei Peoples R China Chongqing Construction Ind Grp Co Ltd Chongqing 400054 Peoples R China Hubei Univ Automot Technol Coll Mech Engn Shiyan 442002 Hubei Peoples R China

Cold radial forging (CRF) is recognized as one of the most effective manufacturing processes for the production of hollow components. Nonetheless, even minor alterations in the alloy composition during the cold deformation processing phase can significantly influence the material's manufacturability. This study addresses the challenges associated with high optimization costs, complex data acquisition, and the prediction of forming quality when integrating multiple processes, such as heat treatment and material composition. We propose the development of an intelligent predictive model aimed at forecasting the forming quality of the 20CrMnTiH alloy during CRF, utilizing a back-propagation neural network optimized by genetic algorithm (GA-BP). The assessment of forming quality is based on parameters such as damage, residual stress, and equivalent strain. The study investigates the impact of alloy composition and spheroidal annealing (SA) process parameters on forming quality. The performance of the three GA-BP prediction models is superior in terms of the coefficient of determination (R2) and mean square error (MSE), when compared to a conventional BP neural network and four other machine learning techniques, including gradient-boosted decision trees, random forests, support vector regression, and logistic regression. A comprehensive comparative analysis of the evaluation metrics across all three prediction models, alongside multi-objective optimization, indicates that the Pareto solution set generated by NSGA-II exhibits optimal distribution uniformity. The optimized process parameters (0.17%C-0.24%Si-0.81%Mn-0.03%P-0.03%S-1.15%Cr-0.05%Ni-0.06%Ti, Te: 60 degrees C, ATi: 4.57 h) resulted in a reduction of residual stresses by 12%, equivalent strain by 15%, and component damage by 30%. The results demonstrate that the methodology proposed in this paper not only enhances the quality of CRF molding but also significantly improves the accuracy of the predictive model for f

关键词： 20CrMnTiH alloy Cold radial forging Alloy composition Spheroidizing annealing GA-BP neural network

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Bill of material consistency reconstruction method for complex products driven by digital twin

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2022年第1-2期120卷 185-202页

作者： Wang, Yunrui Ren, Wenzhe zhang, Chuanwei Zhao, xuwen Xian Univ Sci & Technol Sch Mech Engn Xian 710054 Shaanxi Peoples R China

Bill of material (BOM), as the core data in the complete life cycle management of complex products, is the primary data that supports the deep integration of intelligent and information technology of complex products. They are aiming at the characteristics of high complexity, solid dynamics, and many uncertain factors in the BOM reconstruction process of complex products. The digital twin technology is introduced into the BOM reconstruction process, and the BOM consistency reconstruction mechanism of complex products is constructed. The sequence process of BOM data flow is analyzed. The focus is on the reconstruction process of engineering BOM (EBOM), process BOM (PBOM), manufacturing BOM (MBOM), and maintenance BOM (WBOM) based on digital twin. The rationality of the constructed BOM is verified by establishing a virtual model, which promotes continuous optimization and improvement of the BOM. This paper also discusses the key technologies of data dynamic perception, digital threading, simulation modeling decoupling, and coupling in the process of BOM reconstruction. Finally, the feasibility of the proposed method is verified by combining the BOM reconstruction process of an enterprise bogie and the construction of the bogie twin system, which provides a reference for improving the accuracy, integrity, and consistency of the BOM reconstruction process of complex products.

关键词： Complex products Digital twin Consistency BOM reconstruction

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Stable self-crosslinking phase change composites with vertically aligned boron nitride for high thermal conductivity thermal interface materials

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CERAMICS INTERNATIONAL 2024年第11期50卷 19829-19837页

作者： Liu, Chunlei Duan, Xiaoyuan zhang, Wei Huo, Qianqiang Sui, xuwen Liu, Yaqing Liang, Chaobo North Univ China Coll Mat Sci & Engn Key Lab Funct Nanocomposites Shanxi Prov Taiyuan 030051 Peoples R China Northwestern Polytech Univ Sch Chem & Chem Engn Shaanxi Key Lab Macromol Sci & Technol Xian 710072 Peoples R China

Thermal interface materials (TIMs) must have a high through-plane thermal conductivity in order to efficiently transfer the heat generated by electronic components to heat sinks. Nevertheless, the achievement of high through-plane thermal conductivity is still a great challenge due to the inadequate thermal conductivity network as well as the lack of thermal response from the polymer matrix. Herein, we have developed a solid-solid phase change polymer matrix achieved through self-crosslinking polyethylene glycol (SCPEG). Subsequently, highperformance TIMs based on the SCPEG matrix and vertically aligned boron nitride (BN) nanosheets are obtained by bidirectional freezing, hot pressing, and longitudinal slicing. The prepared BN/SCPEG composites (BN content of 80 vol%) with a vertically oriented network achieved a through-plane thermal conductivity of 23.03 W m-1 K-1. More importantly, the vertically aligned BN nanosheets improve the thermal conductivity of composites, while the SCPEG matrix can reduce the hardness of composites by absorbing the heat, thus decreasing the contact thermal resistance.

关键词： Thermal interface materials Solid-solid phase change polymer matrix Self-crosslinking polyethylene glycol Vertically aligned boron nitride nanosheets

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Finely-Tuning Chemiluminescent Color of CdTe Nanocrystals and Its Application for Near-Infrared Semi-Automatic Immunoassay

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ANALYTICAL CHEMISTRY 2024年第19期96卷 7643-7650页

作者： Ren, Xiaoxuan Tian, Zhijian Gao, xuwen Ai, Yaojia Li, Mengwei zhang, Bin Zou, Guizheng Shandong Univ Sch Chem & Chem Engn Jinan 250100 Peoples R China

Chemiluminescence (CL), especially commercialized CL immunoassay (CLIA), is normally performed within the eye-visible region of the spectrum by exploiting the electronic-transition-related emission of the molecule luminophore. Herein, dual-stabilizers-capped CdTe nanocrystals (NCs) is employed as a model of nanoparticulated luminophore to finely tune the CL color with superior color purity. Initialized by oxidizing the CdTe NCs with potassium periodate (KIO4), intermediates of the reactive oxygen species (ROS) tend to charge CdTe NCs in both series-connection and parallel-connection routes and dominate the charge-transfer CL of CdTe NCs. The CdTe NCs/KIO4 system can exhibit color-tunable CL with the maximum emission wavelength shifted from 694 nm to 801 nm, and the red-shift span is over 100 nm. Both PL and CL of each of the CdTe NCs are bandgap-engineered;the change in the NCs surface state via CL reaction enables CL of each of the CdTe NCs to be red-shifted for similar to 20 nm to PL, while the change in the NCs surface state via labeling CdTe NCs to secondary-antibody (Ab(2)) enables CL of the CdTe NCs-Ab(2) conjugates to be red-shifted for another similar to 20 nm to bare CdTe NCs. The CL of CdTe753-Ab(2)/KIO4 is similar to 791 nm, which can perform near-infrared CL immunoassay and semi-automatically determined procalcitonin (PCT) on commercialized in vitro diagnosis (IVD) instruments.

关键词： Color Monomers Oxygen Peptides and proteins Quantum mechanics

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Optimization of the natural gas hydrate hot water injection production method: Insights from numerical and phase equilibrium analysis

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APPLIED ENERGY 2024年 361卷

作者： zhang, Zhaobin Li, Yuxuan Li, Shouding He, Jianming Li, Xiao Xu, Tao Lu, Cheng Qin, xuwen Chinese Acad Sci Key Lab Shale Gas & Geoengn Inst Geol & Geophys Beijing 100029 Peoples R China Chinese Acad Sci Innovat Acad Earth Sci Beijing 100029 Peoples R China Univ Chinese Acad Sci Coll Earth & Planetary Sci Beijing 100049 Peoples R China Minist Nat Resources China Geol Survey Oil & Gas Resources Survey Beijing 100083 Peoples R China Minist Nat Resources China Geol Survey Guangzhou Marine Geol Survey Guangzhou 510075 Peoples R China

The heat injection during depressurization is a crucial technique for sustaining the long-term gas production rate of natural gas hydrate. To analyze the production patterns and mechanisms of hydrate dissociation under various heat injection conditions and to further optimize heat injection strategies, this study establishes a reservoir-scale three-dimensional heterogeneous computational model using a self-developed hydrate simulator. A novel in-situ heating method utilizing bottom seawater is proposed for heat injection, and comprehensive analyses of heating power and injection rates are conducted. The results indicate that increasing heating power at a constant injection rate enhances gas production rates while reducing thermal efficiency. Simultaneously, under constant heating power, gas production rates initially increase and then decrease with increasing injection rates, revealing the presence of an optimal injection rate. This paper introduces the concepts of temperature driving force and temperature modification ratio, analyzes the mechanisms of heat injection development, and derives an optimized strategy for hot water injection through curve fitting. This research enhances our understanding of the integrated approach involving thermal stimulation and depressurization, providing significant guidance for future production endeavors.

关键词： Natural gas hydrate Thermal stimulation Three-dimensional modelling Temperature driving force Comprehensive analysis

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Luminophore-Surface-Engineering-Enabled Low-Triggering-Potential and Coreactant-Free Electrochemiluminescence for Protein Determination

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ANALYTICAL CHEMISTRY 2023年第17期95卷 6948-6954页

作者： Gao, xuwen Ren, Xiaoxuan Ai, Yaojia Li, Mengwei zhang, Bin Zou, Guizheng Shandong Univ Sch Chem & Chem Engn Jinan 250100 Peoples R China

Coreactant-free electrochemiluminescence (ECL) is promising for removing the exogenous effects of coreactant and simplify the operation procedures and setups of commercialized ECL bioassays. Herein, an electrosterically involved strategy for achieving a low-triggering-potential (+0.21 V vs Ag/AgCl) and coreactant-free ECL from dual-stabilizer-capped CdTe nanocrystals (NCs) is proposed with mercaptopropionic acid (MPA) and hexametaphosphate (HMP) as the capping agents of luminophores. Upon employing the CdTe NCs as the ECL tag for the immunoassay, all the tags in the bioconjugates of the CdTe NCs and the secondary antibody (Ab2|CdTe) as well as in the final achieved sandwich-type immunocomplexes can exhibit efficient coreactant-free ECL with an electrosterically involved triggering potential nature. The bioconjugates of Ab2|CdTe with Ab2 no more than 30 kDa, such as the thyroid stimulating hormone (30 kDa) and the recombinant pro-gastrin releasing peptide (ProGRP, 14 kDa), merely exhibit coreactant-free ECL around +0.24 V, while bioconjugates of Ab2| CdTe with an Ab2 beyond 30 kDa only give off coreactant-free ECL around +0.82 V. Due to the further enhanced electrosteric effect in sandwich-type immunocomplexes, only the ECL immunosensor with ProGRP as the target can give off coreactant-free ECL around +0.24 V. The electrosterically involved and coreactant-free ECL of CdTe NCs is consequently utilized to sensitively and selectively determine the molecular protein ProGRP, which demonstrates a wide linearity range from 0.1 to 2000 pg/mL and a low limit of detection at 0.05 pg/mL (S/N = 3). This low-triggering-potential and coreactant-free combined ECL platform indicates that engineering the surface of CdTe NCs with a protein can improve the performance of ECL tags in a protein-weight-involved electrosterical way.

关键词： Electrochemiluminescence Luminophore

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