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Game theory attack pricing for mining pools in blockchain-based IoT
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作者 Yourong Chen Hao Chen +3 位作者 Zhenyu Xiong Banteng Liu Zhangquan Wang Meng Han 《Digital Communications and Networks》 SCIE CSCD 2024年第4期973-988,共16页
The malicious mining pool can sacrifice part of its revenue to employ the computing power of blockchain network.The employed computing power carries out the pool mining attacks on the attacked mining pool.To realize t... The malicious mining pool can sacrifice part of its revenue to employ the computing power of blockchain network.The employed computing power carries out the pool mining attacks on the attacked mining pool.To realize the win-win game between the malicious mining pool and the employee,the paper proposes an Employment Attack Pricing Algorithm(EAPA)of mining pools in blockchain based on game theory.In the EAPA,the paper uses mathematical formulas to express the revenue of malicious mining pools under the employment attack,the revenue increment of malicious mining pools,and the revenue of the employee.It establishes a game model between the malicious mining pool and the employee under the employment attack.Then,the paper proposes an optimal computing power price selection strategy of employment attack based on model derivation.In the strategy,the malicious mining pool analyzes the conditions for the employment attack,and uses the derivative method to find the optimal utilization value of computing power,employees analyze the conditions for accepting employment,and use the derivative method to find the optimal reward value of computing power.Finally,the strategy finds the optimal employment computing power price to realize Nash equilibrium between the malicious mining pool and the employee under the current computing power allocation.The simulation results show that the EAPA could find the employment computing power price that realizes the win-win game between the malicious mining pool and the employee.The EAPA also maximizes the unit computing power revenue of employment and the unit computing power revenue of honest mining in malicious mining pool at the same time.The EAPA outperforms the state-of-the-art methods such as SPSUCP,DPSACP,and FPSUCP. 展开更多
关键词 Game theory Blockchain PoW Mining pool Employment attack
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A Pooling Method Developed for Use in Convolutional Neural Networks
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作者 Ìsmail Akgül 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第10期751-770,共20页
In convolutional neural networks,pooling methods are used to reduce both the size of the data and the number of parameters after the convolution of the models.These methods reduce the computational amount of convoluti... In convolutional neural networks,pooling methods are used to reduce both the size of the data and the number of parameters after the convolution of the models.These methods reduce the computational amount of convolutional neural networks,making the neural network more efficient.Maximum pooling,average pooling,and minimum pooling methods are generally used in convolutional neural networks.However,these pooling methods are not suitable for all datasets used in neural network applications.In this study,a new pooling approach to the literature is proposed to increase the efficiency and success rates of convolutional neural networks.This method,which we call MAM(Maximum Average Minimum)pooling,is more interactive than other traditional maximum pooling,average pooling,and minimum pooling methods and reduces data loss by calculating the more appropriate pixel value.The proposed MAM pooling method increases the performance of the neural network by calculating the optimal value during the training of convolutional neural networks.To determine the success accuracy of the proposed MAM pooling method and compare it with other traditional pooling methods,training was carried out on the LeNet-5 model using CIFAR-10,CIFAR-100,and MNIST datasets.According to the results obtained,the proposed MAM pooling method performed better than the maximum pooling,average pooling,and minimum pooling methods in all pool sizes on three different datasets. 展开更多
关键词 pooling convolutional neural networks deep learning
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Effects of pooling,specialization,and discretionary task completion on queueing performance
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作者 JIANG Houyuan 《运筹学学报(中英文)》 CSCD 北大核心 2024年第3期81-96,共16页
Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and... Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and disadvantages in different operational environments.This paper uses the M/M/1 and M/M/2 queues to study the impact of pooling,specialization,and discretionary task completion on the average queue length.Closed-form solutions for the average M/M/2 queue length are derived.Computational examples illustrate how the average queue length changes with the strength of pooling,specialization,and discretionary task completion.Finally,several conjectures are made in the paper. 展开更多
关键词 queuing systems pooling SPECIALIZATION discretionary task completion average queue length
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Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation
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作者 Yu Feng Ke Gao Suzanne Lacasse 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1192-1201,共10页
The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely u... The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective. 展开更多
关键词 Overcoring stress measurement Uncertainty reduction Partial pooling Bayesian hierarchical model Nuclear waste repository
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U-Net Based Dual-Pooling Segmentation of Bone Metastases in Thoracic SPECT Bone Scintigrams
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作者 Yang He Qiang Lin +1 位作者 Yongchun Cao Zhengxing Man 《Journal of Computer and Communications》 2024年第4期60-71,共12页
In order to enhance the performance of the CNN-based segmentation models for bone metastases, this study proposes a segmentation method that integrates dual-pooling, DAC, and RMP modules. The network consists of disti... In order to enhance the performance of the CNN-based segmentation models for bone metastases, this study proposes a segmentation method that integrates dual-pooling, DAC, and RMP modules. The network consists of distinct feature encoding and decoding stages, with dual-pooling modules employed in encoding stages to maintain the background information needed for bone scintigrams diagnosis. Both the DAC and RMP modules are utilized in the bottleneck layer to address the multi-scale problem of metastatic lesions. Experimental evaluations on 306 clinical SPECT data have demonstrated that the proposed method showcases a substantial improvement in both DSC and Recall scores by 3.28% and 6.55% compared the baseline. Exhaustive case studies illustrate the superiority of the methodology. 展开更多
关键词 Tumor Bone Metastasis Bone Scintigram Lesion Segmentation CNN Dual pooling
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Expanding the liver donor pool worldwide with hepatitis C infected livers, is it the time?
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作者 Mai Hashem Mohammed A Medhat +1 位作者 Doaa Abdeltawab Nahed A Makhlouf 《World Journal of Transplantation》 2024年第2期13-27,共15页
Liver transplantation(LT)provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma.Despite the increasing number of liver transplants performed each year,the number of LT can... Liver transplantation(LT)provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma.Despite the increasing number of liver transplants performed each year,the number of LT candidates on the waitlist remains unchanged due to an imbalance between donor organ supply and the demand which increases the waitlist time and mortality.Living donor liver transplant had a great role in increasing the donor pool and shortened waitlist time for LT candidates.Nevertheless,further strategies can be implemented to increase the pool of potential donors in deceased donor LT,such as reducing the rate of organ discards.Utilizing hepatitis C virus(HCV)seropositive liver grafts is one of the expanded donor organ criteria.A yearly increase of hundreds of transplants is anticipated as a result of maximizing the utilization of HCV-positive organs for HCV-negative recipients.Direct-acting antiviral therapy's efficacy has revolutionized the treatment of HCV infection and the use of HCV-seropositive donors in transplantation.The American Society of Transplantation advises against performing transplants from HCV-infected liver donors(D+)into HCV-negative recipient(R-)unless under Institutional Review Board-approved study rules and with full informed consent of the knowledge gaps associated with such transplants.Proper selection of patients to be transplanted with HCV-infected grafts and confirming their access to direct-acting antivirals if needed is im-portant.National and international consensuses are needed to regulate this process to ensure the maximum benefit and the least adverse events. 展开更多
关键词 Donor pool Hepatitis C-viremic organs Non-viremic organs Direct acting antivirals Hepatitis C virus treated Liver transplantation
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The impacts of market reform on the market penetration of natural gas-fired electricity and renewable energy in China 被引量:4
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作者 Li-Jing Zhu Yan Li +2 位作者 Yan-Yan Tang Yao-Ming Li Qi Zhang 《Petroleum Science》 SCIE CAS CSCD 2017年第4期831-841,共11页
Natural gas-fired electricity(NGFE) is expected to play a more important role in the future due to its characteristics of low pollution, high efficiency and flexibility. However, its development in China is impeded by... Natural gas-fired electricity(NGFE) is expected to play a more important role in the future due to its characteristics of low pollution, high efficiency and flexibility. However, its development in China is impeded by its high regulation price compared with coal power. Market reform is therefore of vital importance to promote the penetration of NGFE. The objective of this study is to analyze the impacts of market reform and the renewable electricity(RE) subsidy policy on the promotion of NGFE and RE. A dynamic game-theoretic model is developed to analyze the interaction among the NG supplier, the power sector and the power grid. Three scenarios are proposed with different policies, including a fixed regulation price of NG and electricity, real-time pricing(RTP) of NG and electricity, and subsidy targeted at RE. The results show that:(1) market reform can sharply decrease the NG price and consequently promote the development of NGFE and RE;(2) subsidy targeted at RE not only promotes the penetration of NGFE and RE, but also increases the utilization ratio of renewables significantly;(3) market reform and the subsidy also enhance consumers’ welfare by reducing their power consumption expenditure. 展开更多
关键词 Natural gas-fired electricity Renewable electricity Real-time pricing Market reform Game-theoretic model
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Effect of Carbon Price Floor on Levelised Cost of Gas-Fired Generation Technology in the UK
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作者 Tianxiang Luan Kwoklum Lo 《World Journal of Engineering and Technology》 2016年第3期66-71,共7页
The UK government implements carbon price floor to provide long-term incentive to invest in low-carbon technology, thus, fossil-fuel power plants have to face increasing carbon price. This report addresses the effect ... The UK government implements carbon price floor to provide long-term incentive to invest in low-carbon technology, thus, fossil-fuel power plants have to face increasing carbon price. This report addresses the effect of carbon price floor on levelised cost of gas-fired generation technology through the levelised cost of electricity (LCOE) ap-proach with the estimation of carbon price floor. Finally, the comparison of levelised cost of electricity for all generation technology in the UK will be shown and discussed. 展开更多
关键词 Carbon Price Levelised Cost gas-fired Power Plant
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PROSPECT OF GAS-FIRED POWER GENERATION IN CHINA
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作者 Liu Zhihong and Liu Hequn(China Petroleum Planning and Engineering Institute ,CNPC) 《China Oil & Gas》 CAS 1999年第1期60-61,共2页
关键词 GAS PROSPECT OF gas-fired POWER GENERATION IN CHINA 2010
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Simulation of single bubble dynamic process in pool boiling process under microgravity based on phase field method
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作者 朱昶胜 赵博睿 +1 位作者 雷瑶 郭秀婷 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第4期473-481,共9页
We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behavio... We use the phase field method to track the gas-liquid interface based on the gas-liquid two-phase flow in the pool boiling process,and study the bubble nucleation,growth,deformation,departure and other dynamic behaviors on the heating surface under microgravity.By simulating the correlation between liquid undercooling and bubble dynamics,we find that the bubble growth time increases with the increase of liquid undercooling,but the effect of liquid undercooling on bubble height is not significant.Meanwhile,the gas-liquid-solid three-phase contact angle and the gravity level will also have an effect on the bubble growth time and bubble height.With the increase of the contact angle,the bubble growth time and bubble height when the bubble departs also increase.While the effect of gravity level is on the contrary,the smaller the gravity level is,the larger the bubble height and bubble growth time when the bubble separates. 展开更多
关键词 pool boiling single-bubble phase-field method low-gravity
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Genotyping ex situ trees of Abies nebrodensis translocated from the original Sicilian population to enrich the gene pool
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作者 Anna De Rogatis Fulvio Ducci +2 位作者 Serena Guerri Angela Teani Roberta Proietti 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第4期1095-1106,共12页
As a dynamic ex situ conservation strategy,a clonal seed orchard was started in a nursery in Pomaio(POM)in central Italy in 1993 for an assisted migration experiment of Abies nebrodensis(Lojac.)Mattei.Two artifi cial ... As a dynamic ex situ conservation strategy,a clonal seed orchard was started in a nursery in Pomaio(POM)in central Italy in 1993 for an assisted migration experiment of Abies nebrodensis(Lojac.)Mattei.Two artifi cial ex situ populations were planted with this gene pool:a seedling arboretum in Pieve Santo Stefano(PSS)and a small dendrological collection in Papiano(PAP),both originating from the Sicilian relict population.Here,using AFLP markers,we estimated the relatedness among the relocated genotypes of the three collections to check whether the three collections had suffi cient genetic variability to be considered as additional sources of variability to the original gene pool for the assisted migration strategy.High individual genetic variability was found in the collections;each plant had a diff erent genotype and was confi rmed to belong to its population of origin.PAP and PSS trees were shown to be only from the original population of A.nebrodensis species and were derived from a limited set of maternal fertile genotypes.Based on the Sicilian fi r population inventory,nursery production in Sicily,and structure clustering analysis,close genetic relationships among POM,PAP and several PSS trees(1–35)were evident.Similarly,the PSS group(36–78)was genetically close to tree 1 of POM and in a lesser proportion to plants 7 and 9 of POM.The sampling of seedlings used to form batches in the nursery might have infl uenced the structure of the resultant plantations.All genotypes will be useful for enriching the original gene pool. 展开更多
关键词 Sicilian fir GENOTYPING Ex situ conservation Gene pool Assisted migration
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Comparisons of Structured Surface Floors for Pool Boiling Enhancement at Low Heat Fluxes: Hands-On Learning Setup for Heat Transfer Classroom
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作者 Birce Dikici Basim Q. A. Al-Sukaini 《World Journal of Engineering and Technology》 2023年第2期303-318,共16页
Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. ... Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. The pool boiling performance of water under atmospheric pressure of 1.025 bar is investigated by using several structured surfaces at heat fluxes of 28 and 35 kW/m<sup>2</sup>. Surfaces with holes, rectangular grooves, and mushroom fins are manufactured by an NC-controlled vertical milling machine. The heat flux versus excess temperature graph is plotted by using thermocouple measurements of water and base temperatures of the boiling vessel. The separation, rise, and growth of individual vapor bubbles from the surface during boiling were recorded with a digital camera. The results for the plain surface are compared to the Rohsenow correlation. The enhancement of heat transfer coefficient (h) ranged between 15% - 44.5% for all structured surfaces. The highest heat transfer coefficient enhancement is observed between 41% - 56.5% for holed surface-3 (405 holes) compared to the plain surface. The excess temperature dropped around 29% - 34% for holed surface-3 (405 holes) compared to the plain surface. The heat transfer coefficient increases as the spacing between channels or holes decreases. While the bubbles on holed and mushroomed surfaces were spherical, the bubbles on the flat and grooved surfaces were observed as formless. The suggested economical test design could be appropriate to keep students focused and participating in the classroom. 展开更多
关键词 BOILING pool Boiling Heat Transfer Coefficient Enhancement Techniques Engineering Education
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Pooled Sputum for Xpert MTB/RIF Testing: A Cost-Saving Strategy in Mwanza, Tanzania
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作者 Shimba Henerico Richard V. Makapa +4 位作者 Bernard C. Okamo Geoffrey Japhet Lisa Gerwing-Adima Benson R. Kidenya Christa Kasang 《Advances in Infectious Diseases》 2023年第2期183-192,共10页
Background: Tuberculosis (TB) diagnostics, such as Xpert MTB/RIF, is still limited by cost. Testing of pooled samples from presumptive TB patients has been thought as a cost-saving strategy to diagnose TB. We assessed... Background: Tuberculosis (TB) diagnostics, such as Xpert MTB/RIF, is still limited by cost. Testing of pooled samples from presumptive TB patients has been thought as a cost-saving strategy to diagnose TB. We assessed the utility and cost-saving of pooled Xpert MTB/RIF testing strategy for the diagnosis of TB in Mwanza, Tanzania. Methods: Sputum samples from Presumptive TB patients were submitted to TB laboratory for routine diagnosis of TB using Xpert MTB/RIF. The TB results from the individual sputum samples were used as the reference standard and were concealed to the investigating laboratory technicians. The remainder of samples were collected serially and were pooled (5 samples per pool) for testing. The agreement of the results between individual sample testing against pooled sample testing and cost-savings was assessed. Results: A total of 250 sputum samples from presumptive TB patients were analyzed and 50 pools were made with each pool containing 5 samples. Of the 50 sputum pools made, Mycobacterium tuberculosis (MTB) was detected in 17 (34.0%) pools. Results from the individual sputum samples MTB/RIF testing were retrieved for all 250 samples and there were 28 (11.2%) samples in which MTB was detected whereas 222 (88.8%) samples had no MTB detected. Following re-analysis of positive pools, all 28 (100%) individual positive MTB samples were detected within the 17 positive pools, with 1 to 3 individual MTB positive samples per pool. The individual sputum samples were correctly identified by pooled sputum on Xpert MTB/RIF testing, with the sensitivity of 100% and specificity of 100%. Using pooling of sputum samples strategy, we saved 46.0% (115/250) of the cartridges. Conclusion: The pooled sputum testing strategy reduced cartridge costs by 46.0% and has the potential to increase the affordability of Xpert MTB/RIF testing in countries with limited resources, such as Tanzania. 展开更多
关键词 TUBERCULOSIS pooled Sputum Xpert MTB/RIF COST-SAVING Diagnostic Strategy Mwanza Tanzania
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基于改进Faster R-CNN的热轧带钢表面缺陷检测 被引量:1
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作者 邓慧 曾磊 《控制工程》 CSCD 北大核心 2024年第4期752-759,共8页
热轧带钢是钢铁行业的重要产品,其表面缺陷是影响产品质量的重要因素。针对传统缺陷检测算法存在的过程繁琐、精度不足和效率低下等问题,提出一种基于改进更快速区域卷积神经网络(faster region-based convolutional neural network,Fas... 热轧带钢是钢铁行业的重要产品,其表面缺陷是影响产品质量的重要因素。针对传统缺陷检测算法存在的过程繁琐、精度不足和效率低下等问题,提出一种基于改进更快速区域卷积神经网络(faster region-based convolutional neural network,Faster R-CNN)的检测算法,实现对热轧带钢表面缺陷的高效、高精度检测。首先,采用特征相加的方法对底层细节特征和高层语义特征进行融合;然后,采用精准的感兴趣区域池化(precise region of interest pooling,Precise ROI Pooling)获取固定大小的特征向量,避免特征出现位置偏差;最后,利用均值偏移聚类算法对带钢数据集进行聚类,获得适用于热轧带钢表面缺陷检测的先验框尺寸。实验结果表明,所提算法在热轧带钢表面缺陷检测数据集上的平均精度均值达到了85.34%,检测速度为23.5帧/s,且鲁棒性良好,满足实际的工业检测需求。 展开更多
关键词 表面缺陷检测 Faster R-CNN 特征融合 Precise ROI pooling 均值偏移
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表面张力对激光焊接熔池及匙孔的影响 被引量:2
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作者 彭进 许红巧 +4 位作者 杨晓红 王星星 谢世华 李俐群 张定宇 《焊接学报》 EI CAS CSCD 北大核心 2024年第3期7-14,I0003,共9页
基于FLUENT19.0软件,建立了激光焊接热-流耦合模型,对比分析了不同表面张力温度系数(为负值)对熔池流场的影响.结果表明,随着表面张力温度系数的减小,熔池后方顺时针漩涡的流动趋势逐渐减弱,甚至消失,而且焊接飞溅的数量增多.纵截面熔... 基于FLUENT19.0软件,建立了激光焊接热-流耦合模型,对比分析了不同表面张力温度系数(为负值)对熔池流场的影响.结果表明,随着表面张力温度系数的减小,熔池后方顺时针漩涡的流动趋势逐渐减弱,甚至消失,而且焊接飞溅的数量增多.纵截面熔池长度逐渐增加,纵截面熔池流体最大流动速度逐渐增大,熔池横截面的面积逐渐减小.当表面张力温度系数为-2.5×10^(-4)N/(m·K)时,熔池长度平均值为3.28 mm、熔池流体最大流动速度的平均值为2.89 m/s、熔池横截面面积的平均值为4.52 mm^(2);当表面张力温度系数为-3.5×10^(-4)N/(m·K)时,熔池长度平均值为3.73 mm、熔池流体最大流动速度的平均值为3.53 m/s、熔池横截面面积的平均值为4.03 mm^(2);当表面张力温度系数为-4.9×10^(-4)N/(m·K)时,熔池长度平均值为4.14 mm、熔池流体最大流动速度的平均值为4.09 m/s、熔池横截面面积的平均值为3.28 mm^(2). 展开更多
关键词 激光焊接 表面张力 熔池 匙孔
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基于自适应融合的实时车辆检测 被引量:1
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作者 陈婷 朱熟康 +3 位作者 高涛 李浩 涂辉招 李子琦 《同济大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第4期532-540,共9页
针对传统的车辆检测技术检测速度慢和精度低的问题,提出了一种融合注意力的自适应金字塔网络的交通目标检测算法(fusion attentiont adaptive pyramid network,FAAP-Net),可以显著降低交通事故的发生率。为了降低计算复杂度,设计了一种... 针对传统的车辆检测技术检测速度慢和精度低的问题,提出了一种融合注意力的自适应金字塔网络的交通目标检测算法(fusion attentiont adaptive pyramid network,FAAP-Net),可以显著降低交通事故的发生率。为了降低计算复杂度,设计了一种轻量级的互补池化结构(CPS),该结构在宽度和高度上采用了两组不同的池化组合,在保持高精度的同时,显著降低了网络的浮点运算数(GFLOPs)和参数量。为了解决智能交通系统特征图生成过程中的信息损失问题,通过将自适应注意力模块(AAM)和特征增强模块(FEM)引入自适应融合特征金字塔网络(AF-FPN),以融入车辆检测的形状特征。针对车辆细节特征表征弱的问题,引入了一种按通道维度分组的注意力(SA)机制,以增强主干网络对不同车辆检测细节特征的关注,有效提取车辆细节的显著特征。在BDD100K数据集上的实验结果表明,FAAP-Net算法相比于传统算法,平均精度从30.3%提升到43.7%。 展开更多
关键词 目标检测 车辆检测 互补池化 自适应融合 通道维度分组注意力
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基于改进YOLOv8的煤矿输送带异物检测 被引量:1
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作者 洪炎 汪磊 +2 位作者 苏静明 汪瀚涛 李木石 《工矿自动化》 CSCD 北大核心 2024年第6期61-69,共9页
现有基于深度学习的输送带异物检测模型较大,难以在边缘设备部署,且对不同尺寸异物和小目标异物存在错检、漏检情况。针对上述问题,提出一种基于改进YOLOv8的煤矿输送带异物检测方法。采用深度可分离卷积、压缩和激励(SE)网络将YOLOv8... 现有基于深度学习的输送带异物检测模型较大,难以在边缘设备部署,且对不同尺寸异物和小目标异物存在错检、漏检情况。针对上述问题,提出一种基于改进YOLOv8的煤矿输送带异物检测方法。采用深度可分离卷积、压缩和激励(SE)网络将YOLOv8主干网络中C2f模块的Bottleneck重新构建为DSBlock,在保持模型轻量化的同时提升检测性能;为增强对不同尺寸目标物体信息的获取能力,引入高效通道注意力(ECA)机制,并对ECA的输入层进行自适应平均池化和自适应最大池化操作,得到跨通道交互MECA模块,以增强模块的全局视觉信息,进一步提升异物识别精度;将YOLOv8的3个检测头修改为4个轻量化小目标检测头,以增强对小目标的敏感性,有效降低小目标异物的漏检率和错检率。实验结果表明:改进YOLOv8的精确度达91.69%,mAP@50达92.27%,较YOLOv8分别提升了3.09%和4.07%;改进YOLOv8的检测速度达73.92帧/s,可充分满足煤矿输送带异物实时检测的需求;改进YOLOv8的精确度、mAP@50、参数量、权重大小和每秒浮点运算数均优于SSD,Faster-RCNN,YOLOv5,YOLOv7-tiny等主流目标检测算法。 展开更多
关键词 输送带异物检测 YOLOv8 SE网络 高效通道注意力机制 轻量化 小目标检测 自适应平均池化 自适应最大池化
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养老保险省级统筹对养老保险基金平衡的影响研究 被引量:2
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作者 苏春红 耿嫚嫚 李真 《南方经济》 CSSCI 北大核心 2024年第1期22-38,共17页
提高基本养老保险统筹层次是增强养老金支付能力的重要改革举措,也是实现养老金制度安全规范发展的关键。文章基于养老保险省级统筹改革的准自然实验,利用2008-2019年中国A股上市公司数据,构建双重差分模型实证评估了养老保险统筹改革... 提高基本养老保险统筹层次是增强养老金支付能力的重要改革举措,也是实现养老金制度安全规范发展的关键。文章基于养老保险省级统筹改革的准自然实验,利用2008-2019年中国A股上市公司数据,构建双重差分模型实证评估了养老保险统筹改革对企业实际缴费率及基本养老保险基金平衡的影响。研究发现:省级统筹显著降低了企业养老保险实际缴费率,该结果在更改变量度量方式、排除竞争性解释、考虑异质性处理效应等一系列稳健性检验中仍然成立。养老保险省级统筹在不同征管模式、企业类型及地区层面对企业养老保险实际缴费率存在异质性影响,对于社保征收和税务代征模式、劳动密集度高的企业、所在地区老龄化程度低和财政压力小的企业影响更明显。机制分析发现,市县政府由于“相对剥夺效应”和“逐底竞争效应”所产生的征管强度不足是造成省级统筹改革后企业缴费率下降的重要因素。进一步分析表明,省级统筹改革降低了基金收支平衡,并对中西部省份影响更明显。研究对于加强地方政府征管治理、促进养老保险基金平衡发展具有重要启示,为征管主体间利益关系的平衡及养老保险全国统筹的顺利推进提供了经验证据。 展开更多
关键词 养老保险统筹 征管强度 实际缴费率 基金平衡
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基于条带池化与血管增强的眼底图像动静脉分类方法
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作者 肖志涛 彭新文 +3 位作者 刘彦北 耿磊 张芳 王雯 《中国生物医学工程学报》 CAS CSCD 北大核心 2024年第4期438-446,共9页
视网膜血管动静脉管径比是定量分析糖尿病、高血压等慢性疾病的先决条件,是许多心血管疾病的重要风险指标。随着深度学习技术的发展,许多基于卷积神经网络的方法凭借其捕获高级语义的能力,在眼底图像动静脉分类方面取得了较大的进展。然... 视网膜血管动静脉管径比是定量分析糖尿病、高血压等慢性疾病的先决条件,是许多心血管疾病的重要风险指标。随着深度学习技术的发展,许多基于卷积神经网络的方法凭借其捕获高级语义的能力,在眼底图像动静脉分类方面取得了较大的进展。然而,这些方法大多是采用叠加局部卷积和池化操作方式,难以很好地应用于条带形状的眼底视网膜血管。在本研究中,为了更有效地提取条带形状的视网膜血管特征,引入条带池化来捕获空间像素远距离依赖关系,同时考虑到动静脉交错复杂的特性,结合空间金字塔池化并提出了一种全新的混合池化技术以扩大神经网络的感受野和学习上下文信息。另一方面,考虑到眼底图像中血管与非血管分布的比例极不平衡,引入了血管增强模块,利用血管分布信息和高斯核函数约束的血管边缘的信息作为权重校正动静脉特征抑制背景特征,进而解决血管与背景分布比例不平衡问题。在分别包含40、22、45张彩色眼底图像的3种国际公开数据集DRIVE、LES和HRF上的实验表明,所提算法的平衡精度(BACC)分别为0.955、0.946、0.967,表明本研究结合条带池化与血管增强的方法能够较好解决眼底图像中动静脉交错复杂和类别不平衡问题,实现对眼底视网膜动静脉的精确分类,具有较高的应用价值。 展开更多
关键词 眼底图像 动静脉分类 条带池化 混合池化 血管增强
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“抱团取暖”可以应对“寒冬”吗? 贸易政策不确定性与企业协同创新 ——来自中美贸易摩擦的经验证据 被引量:4
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作者 黄宏斌 许晨辉 李圆圆 《财贸研究》 CSSCI 北大核心 2024年第7期35-53,共19页
基于2018年美国政府发起的对华贸易战,运用广义双重差分模型考察贸易政策不确定性对企业协同创新的影响及其作用渠道与经济后果。研究发现:贸易政策不确定性通过加剧融资约束、降低风险承担能力的作用渠道驱动中国企业选择“抱团取暖”... 基于2018年美国政府发起的对华贸易战,运用广义双重差分模型考察贸易政策不确定性对企业协同创新的影响及其作用渠道与经济后果。研究发现:贸易政策不确定性通过加剧融资约束、降低风险承担能力的作用渠道驱动中国企业选择“抱团取暖”,即以“协同创新”的方式谋求技术突破和研发攻关以抵御外部风险。调节效应检验结果发现:当上市公司属于高新技术企业时,贸易政策不确定性对协同创新的驱动效应更为显著;数字化转型为企业间创新要素的聚拢和流动提供了便利,较高的知识产权保护力度降低了企业协同创新中知识被模仿和窃取的风险,因此两者均能够强化贸易政策不确定性对企业协同创新的驱动作用。进一步区分协同创新的主体后发现:当企业面临贸易政策不确定性时,更倾向于选择与供应链上下游企业、高校及科研机构进行协同创新。并且,贸易政策不确定性在促使企业选择协同创新后可显著提升企业未来一期、二期、三期的全要素生产率,从而证实“抱团取暖”的协同创新方式确实能够帮助企业安稳度过“寒冬”。本文丰富了协同创新的驱动机制研究,也为企业在急剧变化的外部贸易环境中以“抱团”方式寻求理性出路提供了参考与借鉴。 展开更多
关键词 中美贸易摩擦 协同创新 融资约束 风险共担
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