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Luminescence regulation of Sb^(3+)in 0D hybrid metal halides by hydrogen bond network for optical anti-counterfeiting
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作者 Dehai Liang Saif M.H.Qaid +5 位作者 Xin Yang Shuangyi Zhao Binbin Luo Wensi Cai Qingkai Qian Zhigang Zang 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2024年第3期15-25,共11页
The Sb^(3+) doping strategy has been proven to be an effective way to regulate the band gap and improve the photophysical properties of organic-inorganic hybrid metal halides(OIHMHs).However,the emission of Sb^(3+) io... The Sb^(3+) doping strategy has been proven to be an effective way to regulate the band gap and improve the photophysical properties of organic-inorganic hybrid metal halides(OIHMHs).However,the emission of Sb^(3+) ions in OIHMHs is primarily confined to the low energy region,resulting in yellow or red emissions.To date,there are few reports about green emission of Sb^(3+)-doped OIHMHs.Here,we present a novel approach for regulating the luminescence of Sb^(3+) ions in 0D C_(10)H_(2)_(2)N_(6)InCl_(7)·H_(2)O via hydrogen bond network,in which water molecules act as agents for hydrogen bonding.Sb^(3+)-doped C_(10)H_(2)2N_(6)InCl_(7)·H_(2)O shows a broadband green emission peaking at 540 nm and a high photoluminescence quantum yield(PLQY)of 80%.It is found that the intense green emission stems from the radiative recombination of the self-trapped excitons(STEs).Upon removal of water molecules with heat,C_(10)H_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7) generates yellow emis-sion,attributed to the breaking of the hydrogen bond network and large structural distortions of excited state.Once water molecules are adsorbed by C_(10)H_(2)_(2)N_(6)In_(1-x)Sb_(x)Cl_(7),it can subsequently emit green light.This water-induced reversible emission switching is successfully used for optical security and information encryption.Our findings expand the under-standing of how the local coordination structure influences the photophysical mechanism in Sb^(3+)-doped metal halides and provide a novel method to control the STEs emission. 展开更多
关键词 indium-based halides Sb^(3+)doping hydrogen bonding network optical anti-counterfeiting
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High-resolution imaging of magnetic fields of banknote anti-counterfeiting strip using fiber diamond probe
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作者 赵旭彤 何飞越 +5 位作者 薛雅文 马文豪 殷筱晗 夏圣开 曾明菁 杜关祥 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期720-727,共8页
Counterfeiting of modern banknotes poses a significant challenge,prompting the use of various preventive measures.One such measure is the magnetic anti-counterfeiting strip.However,due to its inherent weak magnetic pr... Counterfeiting of modern banknotes poses a significant challenge,prompting the use of various preventive measures.One such measure is the magnetic anti-counterfeiting strip.However,due to its inherent weak magnetic properties,visualizing its magnetic distribution has been a longstanding challenge.In this work,we introduce an innovative method by using a fiber optic diamond probe,a highly sensitive quantum sensor designed specifically for detecting extremely weak magnetic fields.We employ this probe to achieve high-resolution imaging of the magnetic fields associated with the RMB 50denomination anti-counterfeiting strip.Additionally,we conduct computer simulations by using COMSOL Multiphysics software to deduce the potential geometric characteristics and material composition of the magnetic region within the anti-counterfeiting strip.The findings and method presented in this study hold broader significance,extending the RMB 50 denomination to various denominations of the Chinese currency and other items that employ magnetic anti-counterfeiting strips.These advances have the potential to significantly improve and promote security measures in order to prevent the banknotes from being counterfeited. 展开更多
关键词 banknote anti-counterfeiting strip nitrogen-vacancy(NV)centers magnetic field imaging numerical simulation
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Identification of a Printed Anti-Counterfeiting Code Based on Feature Guidance Double Pool Attention Networks
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作者 Changhui You Hong Zheng +3 位作者 Zhongyuan Guo Tianyu Wang Jianping Ju Xi Li 《Computers, Materials & Continua》 SCIE EI 2023年第5期3431-3452,共22页
The authenticity identification of anti-counterfeiting codes based on mobile phone platforms is affected by lighting environment,photographing habits,camera resolution and other factors,resulting in poor collection qu... The authenticity identification of anti-counterfeiting codes based on mobile phone platforms is affected by lighting environment,photographing habits,camera resolution and other factors,resulting in poor collection quality of anti-counterfeiting codes and weak differentiation of anti-counterfeiting codes for high-quality counterfeits.Developing an anticounterfeiting code authentication algorithm based on mobile phones is of great commercial value.Although the existing algorithms developed based on special equipment can effectively identify forged anti-counterfeiting codes,the anti-counterfeiting code identification scheme based on mobile phones is still in its infancy.To address the small differences in texture features,low response speed and excessively large deep learning models used in mobile phone anti-counterfeiting and identification scenarios,we propose a feature-guided double pool attention network(FG-DPANet)to solve the reprinting forgery problem of printing anti-counterfeiting codes.To address the slight differences in texture features in high-quality reprinted anti-counterfeiting codes,we propose a feature guidance algorithm that creatively combines the texture features and the inherent noise feature of the scanner and printer introduced in the reprinting process to identify anti-counterfeiting code authenticity.The introduction of noise features effectively makes up for the small texture difference of high-quality anti-counterfeiting codes.The double pool attention network(DPANet)is a lightweight double pool attention residual network.Under the condition of ensuring detection accuracy,DPANet can simplify the network structure as much as possible,improve the network reasoning speed,and run better on mobile devices with low computing power.We conducted a series of experiments to evaluate the FG-DPANet proposed in this paper.Experimental results show that the proposed FG-DPANet can resist highquality and small-size anti-counterfeiting code reprint forgery.By comparing with the existing algorithm based on texture,it is shown that the proposed method has a higher authentication accuracy.Last but not least,the proposed scheme has been evaluated in the anti-counterfeiting code blurring scene,and the results show that our proposed method can well resist slight blurring of anti-counterfeiting images. 展开更多
关键词 Deep learning digital image anti-counterfeiting feature guidance image processing reprint forgery
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Knowledge, Attitudes and Practices Relating to HIV among Motorbike Taxi Drivers in Parakou, Benin, in 2021
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作者 Luc Béhanzin Anicette Yénoukounmè Mahoutin Akodjetin +6 位作者 Yessito Corine Nadège Houéhanou-Sonou Virginie Mongbo Phinées Adégbola Menakpo Ferdinand Adounkpè Maurice Togbédji Agonnoudé David Houéto Thierry Adoukonou 《Open Journal of Epidemiology》 2024年第2期260-272,共13页
Background and Objective: HIV infection is a major global Public Health threat worldwide, particularly in Sub-Saharan Africa of which Benin. The level of knowledge determines the attitudes and behaviors of the populat... Background and Objective: HIV infection is a major global Public Health threat worldwide, particularly in Sub-Saharan Africa of which Benin. The level of knowledge determines the attitudes and behaviors of the populations towards this infection. The study objective was to assess knowledge, attitudes and practices related to HIV infection among motorbike taxi drivers (MTD) in Parakou in 2021. Methods: This was a descriptive cross-sectional study targeting MTD in Parakou in 2021. Participants were selected by cluster sampling. Pretested Digitized questionnaire using KoboCollect<sup>@</sup> applicationserved as a data collection tool. Knowledge, attitudes and practices variable were treated on a score scale. A knowledge score was considered to reflect a good knowledge of HIV if at least two-thirds of the knowledge statements had been correctly answered provided the subject recognized the sexual route as one of modes of HIV transmission, identified at least one preventive measure and meant the incurability of the disease. Quantitative and qualitative variables were appropriately described using the EPI Info 7.1.3.3 software. The participant was classified at positive attitude/practice for HIV prevention, when it has a score of at least 80% and suggests a good preventive measure face a risk of exposure to HIV. Results: A total of 374 subjects were recruited into the study. The mean age was 31.51 ± 7.76 years. Most participants (86.06%) had good knowledge of condom use as an HIV prevention method. The sources of information mentioned were mainly the media (77.07%), relatives or friends (63.38%), and field-workers from non-governmental organizations (37.26%). Routine HIV testing was 50.53%. Among participants, 76.10% reported at least two different sexual partners. Condom use was 59.18 % during the casual sexual intercourse. Within the client-provider relationship with female sex workers, 33.17% had had sexual intercourse with them. The sexual route was the most cited (92.99%), and 90.23% stated that HIV infection can be stabilized by medication in a health structure. Conclusion: The level of knowledge of motorbike taxi drivers in Parakou does not match their behavior with regard to HIV prevention. Appropriate strategies are needed to develop prevention skills in this population. To effectively comb at HIV, it will be necessary to strengthen the targeted HIV preventive interventions at key and bridge populations including motorbike taxi drivers in Benin. 展开更多
关键词 KNOWLEDGE PRACTICE HIV Motorbike taxi Drivers BENIN
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A Combination Prediction Model for Short Term Travel Demand of Urban Taxi
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作者 Mingyuan Li Yuanli Gu +1 位作者 Qingqiao Geng Hongru Yu 《Computers, Materials & Continua》 SCIE EI 2024年第6期3877-3896,共20页
This study proposes a prediction model considering external weather and holiday factors to address the issue of accurately predicting urban taxi travel demand caused by complex data and numerous influencing factors.Th... This study proposes a prediction model considering external weather and holiday factors to address the issue of accurately predicting urban taxi travel demand caused by complex data and numerous influencing factors.The model integrates the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)and Convolutional Long Short Term Memory Neural Network(ConvLSTM)to predict short-term taxi travel demand.The CEEMDAN decomposition method effectively decomposes time series data into a set of modal components,capturing sequence characteristics at different time scales and frequencies.Based on the sample entropy value of components,secondary processing of more complex sequence components after decomposition is employed to reduce the cumulative prediction error of component sequences and improve prediction efficiency.On this basis,considering the correlation between the spatiotemporal trends of short-term taxi traffic,a ConvLSTM neural network model with Long Short Term Memory(LSTM)time series processing ability and Convolutional Neural Networks(CNN)spatial feature processing ability is constructed to predict the travel demand for urban taxis.The combined prediction model is tested on a taxi travel demand dataset in a certain area of Beijing.The results show that the CEEMDAN-ConvLSTM prediction model outperforms the LSTM,Autoregressive Integrated Moving Average model(ARIMA),CNN,and ConvLSTM benchmark models in terms of Symmetric Mean Absolute Percentage Error(SMAPE),Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and R2 metrics.Notably,the SMAPE metric exhibits a remarkable decline of 21.03%with the utilization of our proposed model.These results confirm that our study provides a highly accurate and valid model for taxi travel demand forecasting. 展开更多
关键词 Urban transport taxi travel demand prediction CEEMDAN-ConvLSTM modal components
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Water-sensitive multicolor luminescence in lanthanide-organic framework for anti-counterfeiting 被引量:1
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作者 Tifeng Xia Wenqian Cao +2 位作者 Yuanjing Cui Yu Yang Guodong Qian 《Opto-Electronic Advances》 SCIE 2021年第8期8-15,共8页
The developme nt of high-level an ti-co un terfeiti ng tech niq ues is of great sig nifica nee in econo mics and security issues.However,i ntricate read ing methods are required to obta in multi-level info rmati on st... The developme nt of high-level an ti-co un terfeiti ng tech niq ues is of great sig nifica nee in econo mics and security issues.However,i ntricate read ing methods are required to obta in multi-level info rmati on stored in differe nt colors,which greatly limits the applicati on of an ti-co un terfeit ing tech no logy on sol ving real world problems.Here in,we realize multicolor information anti-counterfeiting under simply external stimulation by utilizing the functional groups and multiple emission centers of lanthanide metal organic framework(Ln-MOFs)to tune luminescence color.Water responsive multicolor luminescence represented by both the tunable color from red to blue within the visible region and high sensitive responsivity has bee n achieved,owing to the in creased nonr adiative decay pathways and enhan ced Eu3+-to-liga nd en ergy back tra nsfer.Remarkably,i nfo rmatio n hidde n in differe nt colors n eeds to be read with a specific water content,which can be used as an en crypti on key to en sure the security of the info rmati on for high-level an ti-co un terfeiti ng. 展开更多
关键词 metal-organic framework multicolor luminescence anti-counterfeiting
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RFID Anti-Counterfeiting for Retailing Systems 被引量:1
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作者 Duy-Thinh Tran Sung Je Hong 《Journal of Applied Mathematics and Physics》 2015年第1期1-9,共9页
Counterfeiting is one of the most serious problems in the consumer market. One promising approach for anti-counterfeiting is to attach a low-cost Radio-frequency Identification (RFID) tag to the product authentication... Counterfeiting is one of the most serious problems in the consumer market. One promising approach for anti-counterfeiting is to attach a low-cost Radio-frequency Identification (RFID) tag to the product authentication. In this paper, we propose an RFID system for detecting counterfeiting products. This RFID system consists of the tag authentication protocol and the database correction protocol. We use the tag authentication protocol for authenticating tags without revealing their sensitive information. This protocol also allows the customer to freely inquire the tag. To prevent the widespread of the counterfeit products, we use the tag status information along with tag identity information. Meanwhile, the database correction protocol guarantees the correctness of the tag status. Our anti-counterfeiting system is the first work considering the seller who plays an important role in the consumer product supply chain. Finally, we show that anti-counterfeiting system is quite secure against counterfeiting and the tag authentication protocol is lightweight enough to be implemented in RFID-based applications. 展开更多
关键词 SECURE RFID System AUTHENTICATION Identification CRYPTOGRAPHIC One-Way Function Counterfeiting anti-counterfeiting LIGHTWEIGHT
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Taxi origin and destination demand prediction based on deep learning:a review
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作者 Dan Peng Mingxia Huang Zhibo Xing 《Digital Transportation and Safety》 2023年第3期176-189,共14页
Taxi demand prediction is a crucial component of intelligent transportation system research.Compared to region-based demand prediction,origin-destination(OD)demand prediction has a wide range of potential applications... Taxi demand prediction is a crucial component of intelligent transportation system research.Compared to region-based demand prediction,origin-destination(OD)demand prediction has a wide range of potential applications,including real-time matching,idle vehicle allocation,ridesharing services,and dynamic pricing,among others.However,because OD demand involves complex spatiotemporal dependence,research in this area has been limited thus far.In this paper,we first review existing research from four perspectives:topology construction,temporal and spatial feature processing,and other relevant factors.We then elaborate on the advantages and limitations of OD prediction methods based on deep learning architecture theory.Next,we discuss ongoing challenges in OD prediction,such as dynamics,spatiotemporal dependence,semantic differentiation,time window selection,and data sparsity problems,and summarize and compare potential solutions to each challenge.These findings offer valuable insights for model selection in OD demand prediction.Finally,we provide public datasets and open-source code,along with suggestions for future research directions. 展开更多
关键词 Deep learning taxi demand prediction taxi OD demand prediction Spatiotemporal data mining Dynamic graph
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网约车平台算法个性化定价、乘客履约率及其监管对策 被引量:1
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作者 冯苏苇 林昌 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第2期104-112,共9页
网约车平台算法个性化定价产生了复杂的市场影响,相比传统出租车服务,网约车乘客违约率达30%左右,因此算法个性化定价对乘客违约率的影响机制以及乘客是否履约的关键特征值得探索。文中尝试运用矩形Hotelling模型建立算法个性化定价与... 网约车平台算法个性化定价产生了复杂的市场影响,相比传统出租车服务,网约车乘客违约率达30%左右,因此算法个性化定价对乘客违约率的影响机制以及乘客是否履约的关键特征值得探索。文中尝试运用矩形Hotelling模型建立算法个性化定价与乘客违约率的因果关联机制,以两个网约车平台之间的Stackelberg博弈模型揭示歧视性定价、乘客违约率与平台之间竞争强度的关系。进一步运用网约车平台订单大数据,以Bhattacharyya距离、提升决策树及改进拉斯维加斯方法(包裹法)等归纳学习工具对网约车平台百万量级订单进行数据挖掘,找出决定乘客是否履约的关键特征。分析结果表明,平台进行个性化定价时乘客的最终消费选择主要取决于价格因素;而改进车辆匹配、派单策略及减少乘客候车时间可显著提高订单履约率。研究结果对网约车平台完善定价及运营策略以维持双边市场用户数量、保证平台持续成功运营具有重要参考价值,也为反垄断部门干预平台个性化定价提供了理论依据。 展开更多
关键词 网约车 算法个性化定价 特征工程 履约率 监管
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Higher Plasma Potassium Level Reduces 10-Year Cardiovascular Disease Risk Predicted by the Framingham Risk Score among Taxi-Motorbike Drivers Residing and Working in Cotonou, Benin
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作者 Patrice Hodonou Avogbe Ambaliou Sanni 《Journal of Biosciences and Medicines》 2023年第4期417-430,共14页
Hypertension, obesity, smoking, dyslipidemia, and type 2 diabetes (T2D) are the major risk factors for developing cardiovascular diseases (CVD). Recent studies revealed that taxi-motorbike drivers (TMDs) in Cotonou ha... Hypertension, obesity, smoking, dyslipidemia, and type 2 diabetes (T2D) are the major risk factors for developing cardiovascular diseases (CVD). Recent studies revealed that taxi-motorbike drivers (TMDs) in Cotonou had higher rates of CVD risk factors, but their impacts on cardiovascular events have rarely been studied. The Framingham risk score (FRS) is an algorithm that considers CVD risk factors and estimates the risk of developing CVD in the next 10 years. Our objectives were to assess the 10-year CVD risk predicted by the FRS, and to examine the relationships of 10-year CVD risk with plasma iron and potassium levels among TMDs. We included 134 TMDs (22 - 59 years old) who had no prior diagnosis of CVD or T2D, and not taking medications affecting iron and potassium homeostasis. Conventional cardiovascular risk factors were used to calculate the 10-year CVD risk, which was categorized as low (20%). FRS > 2%, which corresponded to the 75th percentile of FRS distribution in our study population, was used as a cut-off value to classify participants into two groups. Plasma iron and potassium levels were segregated into tertiles and their associations with 10-year CVD risk were quantified by multivariate-adjusted logistic regression to calculate the odd ratios (ORs) to being above the 75<sup>th</sup> percentile of 10-year CVD risk with the corresponding 95% confidence intervals (CIs). We found that 62.0% of participants had at least one of cardiovascular risk factors. Approximately 97.8% of TMDs had 10-year CVD risk 4.8 mmol/L led to an 83% risk reduction of having 10-year CVD risk > 2% (OR = 0.17, 95% CI: 0.04 - 0.82, P = 0.027). In conclusion, our findings showed that high plasma potassium levels associate with reduced 10-year CVD risk among TMDs. Interventions focused on monitoring of plasma potassium, particularly in those with existing cardiovascular risk factors, may help prevent CVD. 展开更多
关键词 Cardiovascular Diseases 10-Year CVD Risk Cotonou Framingham Risk Score Plasma Potassium taxi-Motorbike Drivers
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时频电磁法在巴什布拉克-乌泊尔构造带深部结构勘探中的应用
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作者 魏巍 高文龙 +5 位作者 王腾宇 高永才 张振 葛大壮 袁菎铭 姚孟远 《物探化探计算技术》 CAS 2024年第3期332-340,共9页
利用时频电磁数据资料,并结合测井资料约束提高电磁反演结果的分辨率,探讨塔西南西部地区巴什布拉克构造带和乌泊尔构造带深层电性结构及其油气分布区域。该区域地形、浅地表形态以及深层地质结构都较为复杂,无法得到有效的地震资料,严... 利用时频电磁数据资料,并结合测井资料约束提高电磁反演结果的分辨率,探讨塔西南西部地区巴什布拉克构造带和乌泊尔构造带深层电性结构及其油气分布区域。该区域地形、浅地表形态以及深层地质结构都较为复杂,无法得到有效的地震资料,严重制约了目标层的油气勘探。时频电磁具有勘探深度大,信噪比高,不受高阻屏蔽的优点。通过对巴什布拉克-乌泊尔区域时频电磁资料进行处理解释,有效识别了该区域的主要断裂及褶皱。南北向和西北向的反演电阻率剖面和极化率剖面,展示了塔西南凹陷同时受南天山和西昆仑山双向挤压的电性结构特征,两侧分别形成逆冲推覆体,呈对冲构造形式,覆盖于塔西南凹陷之上,两侧推覆体发育多排逆冲断层,呈叠瓦状分布,其南侧为乌泊尔构造带,北侧为巴什布拉克构造带,与盆地呈现明显的断层接触关系,南北两侧为区域性大断裂。 展开更多
关键词 塔西南 时频电磁 区域构造 电阻率和极化率
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考虑乘客感知效用的出租车停靠站选址模型
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作者 姬浩 杨爽 +2 位作者 孙睿静 苏兵 贾斌 《西安工业大学学报》 CAS 2024年第2期244-252,共9页
为了解决城市出租车停靠站布局的合理性问题,对出租车GPS数据进行处理并将乘客出行需求点进行聚类,得到出租车停靠站备选点以及乘客出行需求点。基于出租车停靠站服务能力和距离影响因素,结合竞争选址理论构建出租车停靠站对乘客的感知... 为了解决城市出租车停靠站布局的合理性问题,对出租车GPS数据进行处理并将乘客出行需求点进行聚类,得到出租车停靠站备选点以及乘客出行需求点。基于出租车停靠站服务能力和距离影响因素,结合竞争选址理论构建出租车停靠站对乘客的感知效用函数。在此基础上,以覆盖乘客出行需求量最大为目标,建立考虑乘客感知效用的出租车停靠站选址模型,以确定出租车停靠站的最佳位置。根据问题特征设计近似算法A进行求解,在求解大规模算例时,与遗传算法、萤火虫算法相比,近似算法求解精度提高0.91%,求解时间降低约97%。以西安市莲湖区局部区域为例进行实例分析,算法求解近似比为1.64,说明算法的实际使用效果较好。 展开更多
关键词 城市交通 选址优化 近似算法 出租车停靠站 感知效用
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基于AM-LSTM的飞行区航空器滑行轨迹预测与冲突识别
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作者 王兴隆 许晏丰 《中国安全科学学报》 CAS CSCD 北大核心 2024年第1期116-124,共9页
为解决航空器点源定位难以有效预测而引发冲突风险愈来愈多的问题,构建基于注意力机制(AM)和长短期记忆网络(LSTM)的时间序列轨迹预测模型AM-LSTM,预测未来短时间内飞行区航空器的瞬时点源位置;在此基础上,根据航空器型号和滑行航向对... 为解决航空器点源定位难以有效预测而引发冲突风险愈来愈多的问题,构建基于注意力机制(AM)和长短期记忆网络(LSTM)的时间序列轨迹预测模型AM-LSTM,预测未来短时间内飞行区航空器的瞬时点源位置;在此基础上,根据航空器型号和滑行航向对其进行轮廓扩展,以航空器速度作为安全距离权重,通过射线法实现轮廓冲突的判定;并以乌鲁木齐地窝堡机场为例进行验证,利用训练完成的轨迹预测模型预测飞行区航空器滑行轨迹,以识别航空器轮廓间的滑行冲突。结果表明:AM-LSTM预测模型能够准确预测飞行区航空器运动轨迹。未来3 s内轨迹位置预测的平均位移误差为1.05 m,轨迹点位置预测精准性可达94.37%,故能在轨迹预测的基础上精确识别滑行冲突风险,有利于保障飞行区的安全运行。 展开更多
关键词 注意力机制(AM) 长短期记忆网络(LSTM) 飞行区 航空器滑行 滑行轨迹
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飞机牵引滑行工况下前起落架疲劳寿命仿真分析
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作者 孙艳坤 陈银 +2 位作者 张威 刘海涛 魏义礼 《兵器装备工程学报》 CAS CSCD 北大核心 2024年第6期246-252,共7页
为使机场运行更加高效经济,提出一种由牵引车将飞机高速牵引滑行至跑道起飞端的新模式。在牵引滑行工况下,前起落架要承受长时间长距离的高速重载荷牵引,同时受牵引车的加速和制动特性的影响,可能导致前起落架疲劳寿命降低。于是,针对... 为使机场运行更加高效经济,提出一种由牵引车将飞机高速牵引滑行至跑道起飞端的新模式。在牵引滑行工况下,前起落架要承受长时间长距离的高速重载荷牵引,同时受牵引车的加速和制动特性的影响,可能导致前起落架疲劳寿命降低。于是,针对飞机前起落架在该工况下的载荷分析以及疲劳寿命验证十分重要。通过Adams软件建立多体动力学模型,模拟真实工况,对不同牵引滑行速度下的牵引车-飞机系统仿真,获取到前起落架的载荷谱信息。结合前起落架有限元模型静力学分析和载荷谱,通过频域寿命分析法,在nCode软件中计算得到前起落架的疲劳寿命。结果表明,高速牵引滑行工况产生的大载荷加剧前起落架疲劳损伤,疲劳损伤从减震支柱凸耳向下阻力臂延展,疲劳寿命缩短3个数量级,需要对前起落架下阻力臂进行结构优化。本文中的研究可以为新牵引滑行模式下前起落架的疲劳寿命结构优化提供参考。 展开更多
关键词 高速牵引滑行 前起落架 疲劳寿命 联合仿真 载荷谱
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进港航班滑入时间预测
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作者 唐小卫 丁叶 +2 位作者 张生润 任思豫 吴佳琦 《北京航空航天大学学报》 EI CAS CSCD 北大核心 2024年第7期2218-2224,共7页
准确预测进港航班滑入时间对合理调配航班保障资源和提高机场场面运行效率具有重要意义,可有效克服各大机场粗放式预测航班进港时刻的不足,为此提出一种基于机器学习模型的滑入时间预测方法。以首都机场为具体研究对象,分析进港航班滑... 准确预测进港航班滑入时间对合理调配航班保障资源和提高机场场面运行效率具有重要意义,可有效克服各大机场粗放式预测航班进港时刻的不足,为此提出一种基于机器学习模型的滑入时间预测方法。以首都机场为具体研究对象,分析进港航班滑入时间的影响因素并构建特征集;将线性回归、K-最近邻、支持向量机、决策树、随机森林和梯度提升回归树6种在滑出时间预测方面得到广泛应用的机器学习模型用于进港航班滑入时间预测。研究结果表明:在误差范围±3 min内6种机器学习模型的预测精度均超过90%,表明特征集的构建和模型的选择是有效的;综合预测性能与模型拟合评估结果,梯度提升回归树模型的预测效果最好;在梯度提升回归树模型上场面流量特征的贡献度最大,新引入的跨区特征对预测模型的贡献度超过了大部分传统特征。 展开更多
关键词 航空运输 机场场面运行 滑行时间预测 机器学习 梯度提升回归树
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基于Q-Learning的航空器滑行路径规划研究
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作者 王兴隆 王睿峰 《中国民航大学学报》 CAS 2024年第3期28-33,共6页
针对传统算法规划航空器滑行路径准确度低、不能根据整体场面运行情况进行路径规划的问题,提出一种基于Q-Learning的路径规划方法。通过对机场飞行区网络结构模型和强化学习的仿真环境分析,设置了状态空间和动作空间,并根据路径的合规... 针对传统算法规划航空器滑行路径准确度低、不能根据整体场面运行情况进行路径规划的问题,提出一种基于Q-Learning的路径规划方法。通过对机场飞行区网络结构模型和强化学习的仿真环境分析,设置了状态空间和动作空间,并根据路径的合规性和合理性设定了奖励函数,将路径合理性评价值设置为滑行路径长度与飞行区平均滑行时间乘积的倒数。最后,分析了动作选择策略参数对路径规划模型的影响。结果表明,与A*算法和Floyd算法相比,基于Q-Learning的路径规划在滑行距离最短的同时,避开了相对繁忙的区域,路径合理性评价值高。 展开更多
关键词 滑行路径规划 机场飞行区 强化学习 Q-LEARNING
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基于网格划分的常发性拥堵区域识别及演化模式分析
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作者 裴玉龙 李梦如 《交通运输研究》 2024年第2期73-84,共12页
为准确识别常发性拥堵区域,分析其拥堵传播方向,疏通拥堵源头和阻断拥堵传播路径,提出一种基于网格模型和Fuzzy Core DBSCAN算法的常发性拥堵区域识别及演化模式分析方法。首先,对城市路网进行网格化处理,结合出租车GPS数据综合分析网... 为准确识别常发性拥堵区域,分析其拥堵传播方向,疏通拥堵源头和阻断拥堵传播路径,提出一种基于网格模型和Fuzzy Core DBSCAN算法的常发性拥堵区域识别及演化模式分析方法。首先,对城市路网进行网格化处理,结合出租车GPS数据综合分析网格内车辆轨迹数量和轨迹加权平均速度,构建网格内部交通拥堵状态判别模型。然后,利用结合模糊集合论与DBSCAN算法扩展得到的Fuzzy Core DBSCAN算法识别常发性拥堵区域,选取拥堵规模、拥堵传播方向(即两个相邻网格之间的传播次数和传播概率)和关键网格3个指标来分析常发性拥堵的演化模式。最后,以黑龙江省哈尔滨市二环路范围内网格区域为例进行实证分析,结果表明:所识别出的常发性拥堵区域关键网格G(14,13)一周内拥堵传播到相邻网格共85次,其中27次(以31.8%的概率)沿西大直街向北传播至网格G(15,14);与百度地图开放平台数据相比,基于网格模型的拥堵判别结果准确率达85%;基于Fuzzy Core DBSCAN算法识别分析出的常发性拥堵区域拥堵演化模式与百度地图开放平台路况时变过程吻合。这表明融合Fuzzy Core DBSCAN算法与网格模型可有效识别常发性拥堵区域中关键网格的拥堵传播方向,能为制定科学合理的缓堵方案提供支撑。 展开更多
关键词 城市交通 常发性拥堵 网格模型 Fuzzy Core DBSCAN算法 出租车GPS数据
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基于图卷积神经网络的滑行时间预测研究
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作者 彭瑛 侯婧娉 +1 位作者 宛照坤 孙钰 《航空计算技术》 2024年第4期1-6,共6页
为准确预测滑行时间,提出一种基于机场场面运行态势演变的图卷积神经网络预测方法。首先,根据机场场面航空器时空分布情况,从路段流量、路段密度、路段速度等多角度构建交通态势指标体系;其次,利用主成分分析法对指标进行降维处理并利用... 为准确预测滑行时间,提出一种基于机场场面运行态势演变的图卷积神经网络预测方法。首先,根据机场场面航空器时空分布情况,从路段流量、路段密度、路段速度等多角度构建交通态势指标体系;其次,利用主成分分析法对指标进行降维处理并利用K-means算法实现对机场场面路段的态势等级划分,绘制机场场面时空分布热力图;最后,利用图卷积神经网络(GCN)结合门控循环单元(GRU)来获取场面路段特征数据的时空特征,将GRU作为解码器预测输出滑行时间。以深圳宝安国际机场AirTOP仿真数据为例,对所提出的方法进行了分析和验证,并获得了符合预期的预测结果。实验结果表明,该方法在预测滑行时间方面具有有效性。 展开更多
关键词 机场场面 K-MEANS聚类 主成分分析法 图卷积神经网络 滑行时间预测
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基于轨迹相似性的GPS数据快速地图匹配方法研究
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作者 陈仲 《交通工程》 2024年第7期54-59,共6页
提出1种基于网格划分的轨迹相似性匹配技术,能快速高效地应用于海量车辆GPS数据与路网的匹配。首先以实际交叉口为节点构建泰森多边形,将路网划分为子区域;其次,在子区域,按照拓扑关系计算出路网节点之间的所有有效路径轨迹,以欧式距离... 提出1种基于网格划分的轨迹相似性匹配技术,能快速高效地应用于海量车辆GPS数据与路网的匹配。首先以实际交叉口为节点构建泰森多边形,将路网划分为子区域;其次,在子区域,按照拓扑关系计算出路网节点之间的所有有效路径轨迹,以欧式距离作为相似度指标,对有效路径轨迹和车辆GPS轨迹进行相似度测算。该方法大大简化最短路径的重复搜索和计算,同时按照拓扑规则增加了轨迹匹配的方向性约束。本文已应用在某市连续3个月的出租车GPS匹配当中,为城市交通改善提供支撑。 展开更多
关键词 出租车GPS 地图匹配 交通改善
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木聚糖酶TAXI型抑制蛋白的研究进展 被引量:4
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作者 高慧 孙建义 刘明启 《动物营养学报》 CAS CSCD 北大核心 2006年第B12期323-328,共6页
木聚糖酶是一种重要的半纤维素酶,广泛用于饲料工业。近年来在小麦中发现一类能抑制木聚糖酶活性的蛋白,这类抑制蛋白可能会对木聚糖酶的应用效果产生影响。目前发现在不同的谷物中共存在2种类型的木聚糖酶抑制蛋白,根据其结构的不同,分... 木聚糖酶是一种重要的半纤维素酶,广泛用于饲料工业。近年来在小麦中发现一类能抑制木聚糖酶活性的蛋白,这类抑制蛋白可能会对木聚糖酶的应用效果产生影响。目前发现在不同的谷物中共存在2种类型的木聚糖酶抑制蛋白,根据其结构的不同,分为TAXI型(triticum aestivum xylanase inhibitor)和XIP型(xylanase inhibi-tor protein)。本文主要简述了TAXI型抑制蛋白的分子结构、抑制特性和活性影响因素等方面的研究进展,对于深入研究木聚糖酶及其活性影响因子,充分开发利用我国饲料资源和促进畜牧业生产可持续发展具有重要现实意义。 展开更多
关键词 木聚糖酶抑制蛋白 taxi 分子结构 抑制特性
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