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Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process
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作者 Kun Gao Yan Peng 《China Foundry》 SCIE EI CAS CSCD 2024年第1期82-90,共9页
To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wh... To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting process.The effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in detail.In each rotation,the casting wheel passes through four different spray zones.The results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,respectively.The temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed. 展开更多
关键词 casting wheel finite element model grinding thickness casting speed hot face spray zones
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Operational requirements analysis method based on question answering of WEKG
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作者 ZHANG Zhiwei DOU Yajie +3 位作者 XU Xiangqian MA Yufeng JIANG Jiang TAN Yuejin 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第2期386-395,共10页
The weapon and equipment operational requirement analysis(WEORA) is a necessary condition to win a future war,among which the acquisition of knowledge about weapons and equipment is a great challenge. The main challen... The weapon and equipment operational requirement analysis(WEORA) is a necessary condition to win a future war,among which the acquisition of knowledge about weapons and equipment is a great challenge. The main challenge is that the existing weapons and equipment data fails to carry out structured knowledge representation, and knowledge navigation based on natural language cannot efficiently support the WEORA. To solve above problem, this research proposes a method based on question answering(QA) of weapons and equipment knowledge graph(WEKG) to construct and navigate the knowledge related to weapons and equipment in the WEORA. This method firstly constructs the WEKG, and builds a neutral network-based QA system over the WEKG by means of semantic parsing for knowledge navigation. Finally, the method is evaluated and a chatbot on the QA system is developed for the WEORA. Our proposed method has good performance in the accuracy and efficiency of searching target knowledge, and can well assist the WEORA. 展开更多
关键词 operational requirement analysis weapons and equipment knowledge graph(WEKG) question answering(QA) neutral network
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A Comparative Study on the Processing of Emojis and Faces in Human Communication
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作者 TANG Meng-meng SUN Yan-rui 《Journal of Literature and Art Studies》 2024年第8期703-710,共8页
In the digital era,emojis have enriched the way people communicate and research on emojis explosively increased in recent years.However,few noticed their functions from the neurocognitive perspective,especially their ... In the digital era,emojis have enriched the way people communicate and research on emojis explosively increased in recent years.However,few noticed their functions from the neurocognitive perspective,especially their similarities and differences with facial expressions in traditional face-to-face communication.To fill this gap,we conducted a Meta-analysis with 25 independent effect sizes from previous experimental studies.The present study shows that emojis have slight advantages in processing efficiency,which might be attributed to their simplicity in design,namely the omission of complex facial features,but the difference between emoji and face processing is not significant.In addition,emotional valence and experimental methods do not have significant influences,which suggests that emojis are equally effective as human faces in emotional expression.The current research contributes to the knowledge in digital communication and the crucial role played by emojis therein. 展开更多
关键词 emoji processing face processing COMPARISon
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Discourse Analysis Based on Face-Threatening Theory-A Case Study of TucaodahuiⅢ
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作者 ZHOU Qin 《Sino-US English Teaching》 2024年第4期188-193,共6页
Face and politeness are very important parts in people’s daily communication.But people will violate the principle of politeness for protecting their own face.Therefore,they usually choose to use more humorous words ... Face and politeness are very important parts in people’s daily communication.But people will violate the principle of politeness for protecting their own face.Therefore,they usually choose to use more humorous words or jocular words to communicate in order to avoid direct contradictions.Starting from the face-threatening acts in the face theory and politeness principle,this paper briefly analyzes the face-threatening acts and its humorous usage in the TucaodahuiⅢ. 展开更多
关键词 face theory face-threatening acts TucaodahuiⅢ
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A Framework for Driver DrowsinessMonitoring Using a Convolutional Neural Network and the Internet of Things
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作者 Muhamad Irsan Rosilah Hassan +3 位作者 Anwar Hassan Ibrahim Mohamad Khatim Hasan Meng Chun Lam Wan Mohd Hirwani Wan Hussain 《Intelligent Automation & Soft Computing》 2024年第2期157-174,共18页
One of the major causes of road accidents is sleepy drivers.Such accidents typically result in fatalities and financial losses and disadvantage other road users.Numerous studies have been conducted to identify the dri... One of the major causes of road accidents is sleepy drivers.Such accidents typically result in fatalities and financial losses and disadvantage other road users.Numerous studies have been conducted to identify the driver’s sleepiness and integrate it into a warning system.Most studies have examined how the mouth and eyelids move.However,this limits the system’s ability to identify drowsiness traits.Therefore,this study designed an Accident Detection Framework(RPK)that could be used to reduce road accidents due to sleepiness and detect the location of accidents.The drowsiness detectionmodel used three facial parameters:Yawning,closed eyes(blinking),and an upright head position.This model used a Convolutional Neural Network(CNN)consisting of two phases.The initial phase involves video processing and facial landmark coordinate detection.The second phase involves developing the extraction of frame-based features using normalization methods.All these phases used OpenCV and TensorFlow.The dataset contained 5017 images with 874 open eyes images,850 closed eyes images,723 open-mouth images,725 closed-mouth images,761 sleepy-head images,and 1084 non-sleepy head images.The dataset of 5017 images was divided into the training set with 4505 images and the testing set with 512 images,with a ratio of 90:10.The results showed that the RPK design could detect sleepiness by using deep learning techniques with high accuracy on all three parameters;namely 98%for eye blinking,96%for mouth yawning,and 97%for head movement.Overall,the test results have provided an overview of how the developed RPK prototype can accurately identify drowsy drivers.These findings will have a significant impact on the improvement of road users’safety and mobility. 展开更多
关键词 Drowsy drivers convolutional neural network OPENCV MICROPROCESSOR face detection
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Improved Mechanism for Detecting Examinations Impersonations in Public Higher Learning Institutions: Case of the Mwalimu Nyerere Memorial Academy (MNMA)
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作者 Jasson Lwangisa Domition Rogers Philip Bhalalusesa Selemani Ismail 《Journal of Computer and Communications》 2024年第9期160-187,共28页
Currently, most public higher learning institutions in Tanzania rely on traditional in-class examinations, requiring students to register and present identification documents for examinations eligibility verification.... Currently, most public higher learning institutions in Tanzania rely on traditional in-class examinations, requiring students to register and present identification documents for examinations eligibility verification. This system, however, is prone to impersonations due to security vulnerabilities in current students’ verification system. These vulnerabilities include weak authentication, lack of encryption, and inadequate anti-counterfeiting measures. Additionally, advanced printing technologies and online marketplaces which claim to produce convincing fake identification documents make it easy to create convincing fake identity documents. The Improved Mechanism for Detecting Impersonations (IMDIs) system detects impersonations in in-class exams by integrating QR codes and dynamic question generation based on student profiles. It consists of a mobile verification app, built with Flutter and communicating via RESTful APIs, and a web system, developed with Laravel using HTML, CSS, and JavaScript. The two components communicate through APIs, with MySQL managing the database. The mobile app and web server interact to ensure efficient verification and security during examinations. The implemented IMDIs system was validated by a mobile application which is integrated with a QR codes scanner for capturing codes embedded in student Identity Cards and linking them to a dynamic question generation model. The QG model uses natural language processing (NLP) algorithm and Question Generation (QG) techniques to create dynamic profile questions. Results show that the IMDIs system could generate four challenging profile-based questions within two seconds, allowing the verification of 200 students in 33 minutes by one operator. The IMDIs system also tracks exam-eligible students, aiding in exam attendance and integrates with a Short Message Service (SMS) to report impersonation incidents to a dedicated security officer in real-time. The IMDIs system was tested and found to be 98% secure, 100% convenient, with a 0% false rejection rate and a 2% false acceptance rate, demonstrating its security, reliability, and high performance. 展开更多
关键词 Natural Language Processing (NLP) Model Impersonations Detection Dynamic Challenging questions Traditional-in-Class Examination and Impersonation Detection
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Effects of QD2R Numeracy Enhancement Strategy on the Mathematics Performance of Grade 10 Students
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作者 Joshelle N.Abiog 《Journal of Contemporary Educational Research》 2024年第2期256-271,共16页
Learning mathematics requires an effective and strategic teaching approach.This study aimed to assess the mathematics performance of the learners with the implementation of the numeracy enhancement strategy QD2R(Quest... Learning mathematics requires an effective and strategic teaching approach.This study aimed to assess the mathematics performance of the learners with the implementation of the numeracy enhancement strategy QD2R(Questions,Drills,Repetition,and Recitation)and to propose a strategy implementation plan to elevate their performances.This study employed the use of a quasi-experimental research design,purposive sampling with 70 Grade 10 students of Lian National High School who were distributed equally to control and treatment groups.The pre-test and post-test results were statistically analyzed using independent and paired sample t-tests,and a survey questionnaire was examined by getting the mean and standard deviation.The results indicated that better performance was achieved by the students from the treatment group compared to the students from the control group,as revealed by the Mean Percentage Score(MPS)results,mean scores,and P values of their pre-test and post-test scores.The learners’perception of the implementation of this strategy was to a great extent,wherein it was perceived to be more helpful in concepts related to understanding the lesson compared to concepts related to developing their attitude and skills.Moreover,the proposed implementation plan of numeracy enhancement strategy QD2R had three expected outcomes:elevated understanding and performance in mathematics lessons;modified strategy to focus on the development of attitude and skills towards mathematics;and refined and well-implemented QD2R strategy in teaching mathematics.Relative to these expected outcomes,appropriate measures,timeframe,and resources of each were comprehensively formulated. 展开更多
关键词 questions Drills Repetition Recitation Numeracy enhancement strategy PERFORMANCE MAtheMATICS
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Analysis of community question-answering issues via machine learning and deep learning:State-of-the-art review 被引量:3
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作者 Pradeep Kumar Roy Sunil Saumya +2 位作者 Jyoti Prakash Singh Snehasish Banerjee Adnan Gutub 《CAAI Transactions on Intelligence Technology》 SCIE EI 2023年第1期95-117,共23页
Over the last couple of decades,community question-answering sites(CQAs)have been a topic of much academic interest.Scholars have often leveraged traditional machine learning(ML)and deep learning(DL)to explore the eve... Over the last couple of decades,community question-answering sites(CQAs)have been a topic of much academic interest.Scholars have often leveraged traditional machine learning(ML)and deep learning(DL)to explore the ever-growing volume of content that CQAs engender.To clarify the current state of the CQA literature that has used ML and DL,this paper reports a systematic literature review.The goal is to summarise and synthesise the major themes of CQA research related to(i)questions,(ii)answers and(iii)users.The final review included 133 articles.Dominant research themes include question quality,answer quality,and expert identification.In terms of dataset,some of the most widely studied platforms include Yahoo!Answers,Stack Exchange and Stack Overflow.The scope of most articles was confined to just one platform with few cross-platform investigations.Articles with ML outnumber those with DL.Nonetheless,the use of DL in CQA research is on an upward trajectory.A number of research directions are proposed. 展开更多
关键词 answer quality community question answering deep learning expert user machine learning question quality
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Structure of the Quarks and a New Model of Protons and Neutrons: Answer to Some Open Questions
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作者 Ágnes Cziráki 《Natural Science》 CAS 2023年第1期11-18,共8页
The described structural model tries to answer some open questions such as: Why do quarks not exist in the open state? Where are the antiparticles from the Big Bang?
关键词 Structure of Quarks New Model PROTon Neutron Open questions
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The Taiwan Question China From the Perspective of International Crisis Management:History and Future
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作者 ZHANG Sheng WU Zhengru 《International Relations and Diplomacy》 2023年第4期190-194,共5页
The Taiwan Question China discussed in this paper belongs to the theoretical crisis discussion on international relations and does not regard the Cross-Strait relations as relations between different countries.The out... The Taiwan Question China discussed in this paper belongs to the theoretical crisis discussion on international relations and does not regard the Cross-Strait relations as relations between different countries.The outcome of the 2024 Taiwan Election has a great impact on the Taiwan question,the latest poll shows that the possibility of the Democratic Progressive Party(DPP)candidate to come to power is still very high,because its political evolution trend of Taiwan independence still exists. 展开更多
关键词 Taiwan question China international crisis management Taiwan history
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On Answering the Question Related to the Legal Regulation of Working Hours in the New Era:Western Experience and Chinese Approach
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作者 曹燕 XU Chao 《The Journal of Human Rights》 2023年第1期157-181,共25页
The popularity of flexible working hours around the world has slowed down the historical trend of reducing working hours.It even shows signs of regression.Whether and how to guide the cur-rent society with flexible wo... The popularity of flexible working hours around the world has slowed down the historical trend of reducing working hours.It even shows signs of regression.Whether and how to guide the cur-rent society with flexible working hours to return to the historical track of reducing working hours,improve the quality of working hours,and promote a smooth transition from the era of traditional standard work-ing hours to the era of flexible working hours has become a question related to the legal regulation of working hours in the new era.In this regard,although Western countries have proposed new regulatory concepts and carried out legislative practices with distinctive charac-teristics,the limitations of legal regulation capabilities have prevented them from proposing a package of institutional solutions.The advan-tage of China in the ability of legal regulation of working hours has been gradually formed in the legislation on working hours unnder the leadership of the CPC in the past century.It enables China to break through the limitations of the West and propose a Chinese approach to answer the question of the legal regulation of working hours in the new era from three aspects:limiting the extension of working hours,improving the quality of flexible working hours,and optimizing the funnctions of the multi-funnctional regulatory system for working hours. 展开更多
关键词 question related to the legal regulation of working hours in the new era flexible working hours Chinese approach decent working hours quality of working hours working hours capability balanced working hours
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Special Issue:Questions&Data for Better Science and Innovation Call for submissions
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《Journal of Data and Information Science》 CSCD 2024年第3期I0002-I0002,共1页
Editors Yang Wang,Xi'an Jiaotong University Dongbo Shi,Shanghai Jiaotong University Ye Sun,University College London Zhesi Shen,National Science Library,CAS Topic of the Special Issue What are the top questions to... Editors Yang Wang,Xi'an Jiaotong University Dongbo Shi,Shanghai Jiaotong University Ye Sun,University College London Zhesi Shen,National Science Library,CAS Topic of the Special Issue What are the top questions towards better science and innovation and the required data to answer these questions? 展开更多
关键词 COLLEGE questionS ISSUE
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CapsNet-FR: Capsule Networks for Improved Recognition of Facial Features
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作者 Mahmood Ul Haq Muhammad Athar Javed Sethi +3 位作者 Najib Ben Aoun Ala Saleh Alluhaidan Sadique Ahmad Zahid farid 《Computers, Materials & Continua》 SCIE EI 2024年第5期2169-2186,共18页
Face recognition (FR) technology has numerous applications in artificial intelligence including biometrics, security,authentication, law enforcement, and surveillance. Deep learning (DL) models, notably convolutional ... Face recognition (FR) technology has numerous applications in artificial intelligence including biometrics, security,authentication, law enforcement, and surveillance. Deep learning (DL) models, notably convolutional neuralnetworks (CNNs), have shown promising results in the field of FR. However CNNs are easily fooled since theydo not encode position and orientation correlations between features. Hinton et al. envisioned Capsule Networksas a more robust design capable of retaining pose information and spatial correlations to recognize objects morelike the brain does. Lower-level capsules hold 8-dimensional vectors of attributes like position, hue, texture, andso on, which are routed to higher-level capsules via a new routing by agreement algorithm. This provides capsulenetworks with viewpoint invariance, which has previously evaded CNNs. This research presents a FR model basedon capsule networks that was tested using the LFW dataset, COMSATS face dataset, and own acquired photos usingcameras measuring 128 × 128 pixels, 40 × 40 pixels, and 30 × 30 pixels. The trained model outperforms state-ofthe-art algorithms, achieving 95.82% test accuracy and performing well on unseen faces that have been blurred orrotated. Additionally, the suggested model outperformed the recently released approaches on the COMSATS facedataset, achieving a high accuracy of 92.47%. Based on the results of this research as well as previous results, capsulenetworks perform better than deeper CNNs on unobserved altered data because of their special equivarianceproperties. 展开更多
关键词 CapsNet face recognition artificial intelligence
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Adjuvant therapy for hepatocellular carcinoma:Dilemmas at the start of a new era
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作者 Jian-Hong Zhong 《World Journal of Gastroenterology》 SCIE CAS 2024年第8期806-810,共5页
Approximately 50%-70%of patients with hepatocellular carcinoma experience recurrence within five years after curative hepatic resection or ablation.As a result,many patients receive adjuvant therapy after curative res... Approximately 50%-70%of patients with hepatocellular carcinoma experience recurrence within five years after curative hepatic resection or ablation.As a result,many patients receive adjuvant therapy after curative resection or ablation in order to prolong recurrence-free survival.The therapy recommended by national guidelines can differ,and guidelines do not specify when to initiate adjuvant therapy or how long to continue it.These and other unanswered questions around adjuvant therapies make it difficult to optimize them and determine which may be more appropriate for a given type of patient.These questions need to be addressed by clinicians and researchers. 展开更多
关键词 Adjuvant therapy Hepatocellular carcinoma Tumor recurrence Unanswered questions
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MKEAH:Multimodal knowledge extraction and accumulation based on hyperplane embedding for knowledge-based visual question answering
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作者 Heng ZHANG Zhihua WEI +6 位作者 Guanming LIU Rui WANG Ruibin MU Chuanbao LIU Aiquan YUAN Guodong CAO Ning HU 《虚拟现实与智能硬件(中英文)》 EI 2024年第4期280-291,共12页
Background External knowledge representations play an essential role in knowledge-based visual question and answering to better understand complex scenarios in the open world.Recent entity-relationship embedding appro... Background External knowledge representations play an essential role in knowledge-based visual question and answering to better understand complex scenarios in the open world.Recent entity-relationship embedding approaches are deficient in representing some complex relations,resulting in a lack of topic-related knowledge and redundancy in topic-irrelevant information.Methods To this end,we propose MKEAH:Multimodal Knowledge Extraction and Accumulation on Hyperplanes.To ensure that the lengths of the feature vectors projected onto the hyperplane compare equally and to filter out sufficient topic-irrelevant information,two losses are proposed to learn the triplet representations from the complementary views:range loss and orthogonal loss.To interpret the capability of extracting topic-related knowledge,we present the Topic Similarity(TS)between topic and entity-relations.Results Experimental results demonstrate the effectiveness of hyperplane embedding for knowledge representation in knowledge-based visual question answering.Our model outperformed state-of-the-art methods by 2.12%and 3.24%on two challenging knowledge-request datasets:OK-VQA and KRVQA,respectively.Conclusions The obvious advantages of our model in TS show that using hyperplane embedding to represent multimodal knowledge can improve its ability to extract topic-related knowledge. 展开更多
关键词 Knowledge-based visual question answering HYPERPLANE Topic-related
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The Relation between Mental Workload and Face Temperature in Flight Simulation
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作者 Amin Bonyad Hamdi Ben Abdessalem Claude Frasson 《Journal of Behavioral and Brain Science》 2024年第2期64-92,共29页
In this research, we study the relationship between mental workload and facial temperature of aircraft participants during a simulated takeoff flight. We conducted experiments to comprehend the correlation between wor... In this research, we study the relationship between mental workload and facial temperature of aircraft participants during a simulated takeoff flight. We conducted experiments to comprehend the correlation between work and facial temperature within the flight simulator. The experiment involved a group of 10 participants who played the role of pilots in a simulated A-320 flight. Six different flying scenarios were designed to simulate normal and emergency situations on airplane takeoff that would occur in different levels of mental workload for the participants. The measurements were workload assessment, face temperatures, and heart rate monitoring. Throughout the experiments, we collected a total of 120 instances of takeoffs, together with over 10 hours of time-series data including heart rate, workload, and face thermal images and temperatures. Comparative analysis of EEG data and thermal image types, revealed intriguing findings. The results indicate a notable inverse relationship between workload and facial muscle temperatures, as well as facial landmark points. The results of this study contribute to a deeper understanding of the physiological effects of workload, as well as practical implications for aviation safety and performance. 展开更多
关键词 Mental Workload EEG thermal Images Flight Simulation AVIATIon Face Temperature
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PAL-BERT:An Improved Question Answering Model
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作者 Wenfeng Zheng Siyu Lu +3 位作者 Zhuohang Cai Ruiyang Wang Lei Wang Lirong Yin 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期2729-2745,共17页
In the field of natural language processing(NLP),there have been various pre-training language models in recent years,with question answering systems gaining significant attention.However,as algorithms,data,and comput... In the field of natural language processing(NLP),there have been various pre-training language models in recent years,with question answering systems gaining significant attention.However,as algorithms,data,and computing power advance,the issue of increasingly larger models and a growing number of parameters has surfaced.Consequently,model training has become more costly and less efficient.To enhance the efficiency and accuracy of the training process while reducing themodel volume,this paper proposes a first-order pruningmodel PAL-BERT based on the ALBERT model according to the characteristics of question-answering(QA)system and language model.Firstly,a first-order network pruning method based on the ALBERT model is designed,and the PAL-BERT model is formed.Then,the parameter optimization strategy of the PAL-BERT model is formulated,and the Mish function was used as an activation function instead of ReLU to improve the performance.Finally,after comparison experiments with traditional deep learning models TextCNN and BiLSTM,it is confirmed that PALBERT is a pruning model compression method that can significantly reduce training time and optimize training efficiency.Compared with traditional models,PAL-BERT significantly improves the NLP task’s performance. 展开更多
关键词 PAL-BERT question answering model pretraining language models ALBERT pruning model network pruning TextCNN BiLSTM
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Determinants of COVID-19 Face Mask Litter in Coastal Urban Parking Lots: Implications for Source Modelling of Potential Microplastic Pollution
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作者 Robert France Brandon Heung 《Journal of Environmental Protection》 2024年第8期874-886,共13页
Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beac... Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beaches. For the far fewer number of studies conducted on inland and urban locations, the site-specific focus has primarily been surveys along the length of streets. The present study is the first to specifically assess the standing stock (i.e., moment-in-time) of littered face masks for the entire surface area of urban parking lots. The density of face masks in 50 parking lots in a Canadian coastal town (0.00054 m2 ± 0.00051 m2) was found to be significantly greater than the background level of littering of town streets. Face mask density was significantly related to visitation “usage” of parking lots as gauged by the areal size of the lots and of their onsite buildings, as well as the number of vehicles present. Neither parking lot typology nor estimates of inferred export (various measures of wind exposure) and entrapment (various metrics of obstruction) of face masks had a significant influence on the extent of whole-lot littering. In consequence, modelling of the potential input of mask-derived microplastics to the marine environment from coastal communities can use the areal density of face masks found here in association with the total surface area of lots for individual municipalities as determined through GIS analysis. 展开更多
关键词 COVID Face Masks Parking Lot Litter Prediction Areal Abundance
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Three-dimensional pseudo-dynamic reliability analysis of seismic shield tunnel faces combined with sparse polynomial chaos expansion
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作者 GUO Feng-qi LI Shi-wei ZOU Jin-Feng 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期2087-2101,共15页
To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on ... To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on the upper-bound theory of limit analysis,an improved three-dimensional discrete deterministic mechanism,accounting for the heterogeneous nature of soil media,is formulated to evaluate seismic face stability.The metamodel of failure probabilistic assessments for seismic tunnel faces is constructed by integrating the sparse polynomial chaos expansion method(SPCE)with the modified pseudo-dynamic approach(MPD).The improved deterministic model is validated by comparing with published literature and numerical simulations results,and the SPCE-MPD metamodel is examined with the traditional MCS method.Based on the SPCE-MPD metamodels,the seismic effects on face failure probability and reliability index are presented and the global sensitivity analysis(GSA)is involved to reflect the influence order of seismic action parameters.Finally,the proposed approach is tested to be effective by a engineering case of the Chengdu outer ring tunnel.The results show that higher uncertainty of seismic response on face stability should be noticed in areas with intense earthquakes and variation of seismic wave velocity has the most profound influence on tunnel face stability. 展开更多
关键词 reliability analysis shield tunnel face sparse polynomial chaos expansion modified pseudo-dynamic approach seismic stability assessment
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Development of a DFN-based probabilistic block theory approach for bench face angle design in open pit mining
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作者 Jianhua Yan Xiansen Xing +4 位作者 Zhihai Li Weida Ni Liuyuan Zhao Chun Zhu Yuanyuan He 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3047-3062,共16页
In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face ... In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable mining.This study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks testing.The proposed approach was applied to a granite mine in China.First,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit slopes.Then,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each sector.Finally,a bench face angle was determined commensurate with an acceptable risk level of stability.The simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities. 展开更多
关键词 Open pit mine Bench face angle Block theory Probabilistic approach Discrete fracture network modeling Fractured rock slope
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