检索结果-南通市图书馆

The Completeness of Accreting Neutron Star Binary Candidates from the Chinese Space Station Telescope

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第9期24卷 28-36页

作者： Hao Shen Shun-Yi Lan Xiang-Cun Meng Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China international centre of Supernovae Yunnan Key LaboratoryKunming 650216China

A neutron star(NS)has many extreme physical conditions,and one may obtain some important information about an NS via accreting neutron star binary(ANSB)*** upcoming Chinese Space Station Telescope(CSST)provides an opportunity to search for a large sample of ANSB *** goal is to check the completeness of the potential ANSB samples from CSST *** this paper,we generate some ANSBs and normal binaries under the CSST photometric system by binary evolution and binary population synthesis method and use a machine learning method to train a classification *** the Precision(94.56%)of our machine learning model is as high as before study,the Recall is only about 63.29%.The Precision/Recall is mainly determined by the mass transfer rate between the NSs and their *** addition,we also find that the completeness of ANSB samples from CSST photometric data by the machine learning method also depends on the companion mass and the age of the *** candidates with a low initial mass companion star(0.1 M_(⊙)to 1 M_(⊙))have a relatively high Precision(94.94%)and high Recall(86.32%),whereas ANSB candidates with a higher initial mass companion star(1.1 M_(⊙)to 3 M_(⊙))have similar Precision(93.88%)and quite low Recall(42.67%).Our results indicate that although the machine learning method may obtain a relatively pure sample of ANSBs,a completeness correction is necessary for one to obtain a complete sample.

关键词： stars:neutron X-rays:binaries methods:analytical

Mapping Air Quality Using Remote Sensing Technology: A Case Study of Nairobi County

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Open Journal of Air Pollution 2024年第1期13卷 1-22页

作者： Quinto Juma Meltus Faith Njoki Karanja Geospatial Engineering Department The University of Nairobi (UoN) Nairobi Kenya data Management Modeling and Geoinformation Unit (DMMG) International Centre of Insect Physiology and Ecology (ICIPE) Nairobi Kenya

Nairobi County experiences rapid industrialization and urbanization that contributes to the deteriorating state of air quality, posing a potential health risk to its growing population. Currently, in Nairobi County, most air quality monitoring stations use low-cost, inaccurate monitors prone to defects. The study’s objective was to map Nairobi County’s air quality using freely available remotely sensed imagery. The Air Pollution Index (API) formula was used to characterize the air quality from cloud-free Landsat satellite images i.e., Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 OLI from Google Earth Engine. The API values were computed based on vegetation indices namely NDVI, TVI, DVI, and the SWIR1 and NIR bands on the QGIS platform. Qualitative accuracy assessment was done using sample points drawn from residential, industrial, green spaces, and traffic hotspot categories, based on a passive-random sampling technique. In this study, Landsat 5 API imagery for 2010 provided a reliable representation of local conditions but indicated significant pollution in green spaces, with recorded values ranging from -143 to 334. The study found that Landsat 7 API imagery in 2002 showed expected results with the range of values being -55 to 287, while Landsat 8 indicated high pollution levels in Nairobi. The results emphasized the importance of air quality factors in API calibration and the unmatched spatial coverage of satellite observations over ground-based monitoring techniques. The study recommends the recalibration of the API formula for characteristic regions, exploring newer satellite sensors like those onboard Landsat 9 and Sentinel 2, and involving key stakeholders in a discourse to develop a suitable Kenyan air quality index.

关键词： Air Quality Air Pollution Index (API) Satellite Imagery Vegetation Indices Nairobi County

A summary of UNSCEAR evaluation on occupational exposure to ionizing radiation and call for more representative data in broader range of occupational sectors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Radiation Medicine and Protection 2024年第1期5卷 11-15页

作者： Jing Chen United Nations Scientific Committee on the Effects of Atomic Radiation Vienna International CentreP.O.Box 5001400ViennaAustria

The annex D of the United Nations Scientific Committee on the Effects of Atomic Radiation(UNSCEAR)2020/2021 Report presented a comprehensive global estimate of occupational exposure to ionizing *** worldwide annual number of workers exposed to natural and human-made sources of ionizing radiation was estimated to be approximately 24 million in the period *** 52% of those were employed in the sectors that involve exposure to natural sources of *** worldwide average annual effective dose for all workers during the period 2010-2014 was estimated to be around 1.2 mSv-about two thirds of the value estimated for the period *** annual effective dose was estimated to be around 2.0 mSv for workers exposed to natural sources and 0.5 mSv for workers exposed to human-made *** overriding limitation of current evaluation was the low rate of participation by United Nations Member States in providing occupational exposure monitoring data,especially data from non-nuclear sectors and occupational sectors involving naturally occurring radioactive *** the assessment of the worldwide occupational exposure is a complex task,the Committee relies on the collection of up-to-date data on occupational exposure from United Nations Member States in a broad range of occupational sectors,and continues collaboration with international organizations.

关键词： Occupational exposure Ionizing radiation United Nations Scientific Committee on the Effects of Atomic Radiation

Modelling the Survival of Western Honey Bee Apis mellifera and the African Stingless Bee Meliponula ferruginea Using Semiparametric Marginal Proportional Hazards Mixture Cure Model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of data Analysis and Information Processing 2024年第1期12卷 24-39页

作者： Patience Isiaho Daisy Salifu Samuel Mwalili Henri E. Z. Tonnang Department of Statistics and Actuarial Sciences Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya data Management Modelling and Geo-Information Unit International Centre of Insect Physiology and Ecology (icipe) Nairobi Kenya

Classical survival analysis assumes all subjects will experience the event of interest, but in some cases, a portion of the population may never encounter the event. These survival methods further assume independent survival times, which is not valid for honey bees, which live in nests. The study introduces a semi-parametric marginal proportional hazards mixture cure (PHMC) model with exchangeable correlation structure, using generalized estimating equations for survival data analysis. The model was tested on clustered right-censored bees survival data with a cured fraction, where two bee species were subjected to different entomopathogens to test the effect of the entomopathogens on the survival of the bee species. The Expectation-Solution algorithm is used to estimate the parameters. The study notes a weak positive association between cure statuses (ρ1=0.0007) and survival times for uncured bees (ρ2=0.0890), emphasizing their importance. The odds of being uncured for A. mellifera is higher than the odds for species M. ferruginea. The bee species, A. mellifera are more susceptible to entomopathogens icipe 7, icipe 20, and icipe 69. The Cox-Snell residuals show that the proposed semiparametric PH model generally fits the data well as compared to model that assume independent correlation structure. Thus, the semi parametric marginal proportional hazards mixture cure is parsimonious model for correlated bees survival data.

关键词： Mixture Cure Models Clustered Survival data Correlation Structure Cox-Snell Residuals EM Algorithm Expectation-Solution Algorithm

Comparison of Semi-Parametric Shared Frailty Models for Bees’Survival

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of data Analysis and Information Processing 2024年第2期12卷 267-288页

Survival analysis is a fundamental tool in medical science for time-to-event data. However, its application to colony organisms like bees poses challenges due to their social nature. Traditional survival models may not accurately capture the interdependence among individuals within a colony. Frailty models, accounting for shared risks within groups, offer a promising alternative. This study evaluates the performance of semi-parametric shared frailty models (gamma, inverse normal, and positive stable-in comparison to the traditional Cox model using bees’ survival data). We examined the effect of misspecification of the frailty distribution on regression and heterogeneity parameters using simulation and concluded that the heterogeneity parameter was more sensitive to misspecification of the frailty distribution and choice of initial parameters (cluster size and true heterogeneity parameter) compared to the regression parameter. From the data, parameter estimates for covariates were close for the four models but slightly higher for the Cox model. The shared gamma frailty model provided a better fit to the data in comparison with the other models. Therefore, when focusing on regression parameters, the gamma frailty model is recommended. This research underscores the importance of tailored survival methodologies for accurately analyzing time-to-event data in social organisms.

关键词： Correlated Failure Times Frailty Survival Analysis Unobserved Heterogeneity

Survey of Indoor Localization Based on Deep Learning

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第5期79卷 3261-3298页

作者： Khaldon Azzam Kordi Mardeni Roslee Mohamad Yusoff Alias Abdulraqeb Alhammadi Athar Waseem Anwar Faizd Osman centre for Wireless Technology Faculty of EngineeringMultimedia UniversityCyberjaya63100Malaysia Communication Systems&Networks Research Lab Malaysia-Japan International Institute of TechnologyUniversiti Teknologi MalaysiaKuala Lumpur54100Malaysia Department of Electrical Engineering(DEE) International Islamic UniversityIslamabad44000Pakistan Rohde&Schwarz(M)Sdn Bhd Shah Alam40150Malaysia

This study comprehensively examines the current state of deep learning (DL) usage in indoor *** emphasizes the significance and efficiency of convolutional neural networks (CNNs) and recurrent neuralnetworks (RNNs). Unlike prior studies focused on single sensor modalities like Wi-Fi or Bluetooth, this researchexplores the integration of multiple sensor modalities (e.g.,Wi-Fi, Bluetooth, Ultra-Wideband, ZigBee) to expandindoor localization methods, particularly in obstructed environments. It addresses the challenge of precise objectlocalization, introducing a novel hybrid DL approach using received signal information (RSI), Received SignalStrength (RSS), and Channel State Information (CSI) data to enhance accuracy and stability. Moreover, thestudy introduces a device-free indoor localization algorithm, offering a significant advancement with potentialobject or individual tracking applications. It recognizes the increasing importance of indoor positioning forlocation-based services. It anticipates future developments while acknowledging challenges such as multipathinterference, noise, data standardization, and scarcity of labeled data. This research contributes significantly toindoor localization technology, offering adaptability, device independence, and multifaceted DL-based solutionsfor real-world challenges and future advancements. Thus, the proposed work addresses challenges in objectlocalization precision and introduces a novel hybrid deep learning approach, contributing to advancing *** deep learning-based indoor localization techniques have improved accuracy, challenges likedata noise, standardization, and availability of training data persist. However, ongoing developments are expectedto enhance indoor positioning systems to meet real-world demands.

关键词： Deep learning indoor localization wireless-based localization

High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第3期13卷 310-322页

作者： Yixuan Hu Mariappan Anandkumar Yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan Madhav Reddy School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Materials Science and Metallurgical Engineering Indian Institute of Technology HyderabadSangareddy 502285India international Advanced Research centre for Powder Metallurgy and New Materials(ARCI) Hyderabad 500005India

Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature *** the concept of high entropy,high-entropy fluorite oxides(HEFOs)have showcased intriguing high-temperature application ***,unlocking this potential necessitates an assessment of their long-term stability under high-temperature *** this study,we conducted a prolonged heat treatment at 1000℃on typical HEFO,specifically(CeHfZrGdLa)O_(x).After 100 h,high-intensity X-ray diffraction(XRD)revealed a transition from a single-phase fluorite to a multi-phase *** investigation by analytical electron microscoy(AEM)demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures,leading to spontaneous segregation and separation of Ce and La elements,forming Ce-rich,La-poor,and La-rich ***,the La-rich phase spontaneously transformed from a fluorite structure(space group Fm3m)to a bixbyite structure(space group Ia3)at elevated temperatures,resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction *** the intricate phase decomposition,the energy band gap showed minimal variation,suggesting potential property stability of(CeHfZrGdLa)O_(x)across a broad range of *** findings offer valuable insights into the future applications of HEFOs.

关键词： phase transition high-temperature stability elemental segregation high-entropy fluorite oxides(HEFOs)

A summary of UNSCEAR evaluation on medical exposure to ionizing radiation and call for more representative data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Radiation Medicine and Protection 2024年第1期5卷 7-10页

作者： Jing Chen United Nations Scientific Committee on the Effects of Atomic Radiation Vienna International CentreP.O.Box 5001400ViennaAustria

The annex A of the United Nations Scientific Committee on the Effects of Atomic Radiation(UNSCEAR)2020/2021 Report presented a comprehensive global estimate of frequencies and doses from medical exposure to ionizing radiation,their distribution and trends for the period *** annex considered four general categories of medical practice using ionizing radiation:(a)diagnostic radiology,including dental radiology and computed tomography,(b)interventional radiology(image-guided interventional procedures),(c)nuclear medicine,and(d)radiation *** the period 2009-2018,about 4.2 billion medical radiological examinations were performed annually,resulting in an annual effective dose of 0.57 mSv per *** use of computed tomography has continued to grow and the contribution from interventional radiology has increased rapidly in recent *** annual number of radionuclide therapy treatments has increased by 60% since the UNSCEAR 2008 Report,while the number of courses of radiation therapy has increased by 22%.Medical exposure remains by far the largest human-made source of radiation exposure to the *** Committee's evaluation relies on the collection of up-to-date and representative exposure data from all Member States of the United *** exposure survey should be more relevant and useful and adapted to changing data sources and changing uses of radiation across the world.

关键词： Medical exposure Ionizing radiation United Nations Scientific Committee on the Effects of Atomic Radiation

Understanding the catalysis of chromium trioxide added magnesium hydride for hydrogen storage and Li ion battery applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第3期12卷 1117-1130页

作者： D.Pukazhselvan IhsanÇaha Catarina de Lemos Sergey M.Mikhalev Francis Leonard Deepak Duncan Paul Fagg Department of Mechanical Engineering TEMA-Centre for Mechanical Technology and AutomationUniversity of AveiroAveiro 3810-193Portugal LASI-Intelligent Systems Associate Laboratory Guimarães 4800-058Portugal Nanostructured Materials Group International Iberian Nanotechnology Laboratory(INL)Avenida Mestre Jose VeigaBraga 4715-330Portugal

This study explores how the chemical interaction between magnesium hydride(MgH_(2))and the additive CrO_(3) influences the hydrogen/lithium storage characteristics of MgH_(2).We have observed that a 5 wt.%CrO_(3) additive reduces the dehydrogenation activation energy of MgH_(2) by 68 kJ/mol and lowers the required dehydrogenation temperature by 80℃.CrO_(3) added MgH_(2) was also tested as an anode in an Li ion battery,and it is possible to deliver over 90%of the total theoretical capacity(2038 mAh/g).Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH_(2).In depth characterization study by X-ray diffraction(XRD)technique provides convincing evidence that the CrO_(3) additive interacts with MgH_(2) and produces Cr/MgO *** free energy analyses confirm the thermodynamic feasibility of conversion from MgH_(2)/CrO_(3) to MgO/Cr,which is well supported by the identification of Cr(0)in the powder by X ray photoelectron spectroscopy(XPS)*** high resolution transmission electron microscopy(HRTEM)and energy dispersive spectroscopy(EDS)we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt *** is also convincing ground to consider that MgO rock salt accommodates Cr in the *** observations support the argument that creation of active metal–metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH_(2),both for the improved storage of hydrogen and lithium.

关键词： Hydrogen storage Rechargeable batteries Binary hydrides Metal oxides Catalytic mechanism.