期刊文献+
共找到316,454篇文章
< 1 2 250 >
每页显示 20 50 100
气象观测场在汽车试验场中的应用研究
1
作者 陈海建 《时代汽车》 2024年第14期172-174,178,共4页
汽车试验场作为汽车开展道路测试的重要场所,用于验证汽车产品的品质以及可靠性。除了场地道路外,气象条件作为汽车道路测试的重要一环,在《GB/T12534-1990汽车道路试验方法通则》中也有明确要求,如:试验时应是无雨无雾天气,相对湿度小... 汽车试验场作为汽车开展道路测试的重要场所,用于验证汽车产品的品质以及可靠性。除了场地道路外,气象条件作为汽车道路测试的重要一环,在《GB/T12534-1990汽车道路试验方法通则》中也有明确要求,如:试验时应是无雨无雾天气,相对湿度小于95%,气温0-40℃,风速不大于3m/s。同时气象条件也作为试验场道路管控的重要依据,实时风速、雨量、能见度等信息为场地管理者发布限速、限行、封场等通知提供必要参考依据,直接影响道路测试安全管控的及时性。因此,文章从气象观测场的建设、气象服务、异常天气道路管控等方面开展气象观测场在汽车试验场中的应用研究。 展开更多
关键词 products. In addition to the SITE roads METEOROLOGICAL conditions are an important part of AUTOMOTIVE ROAD testing and there are also clear requirements in the GB/T12534-1990 General Rules for AUTOMOTIVE ROAD Test Methods. For example the test should be conducted in rain and fog free weather with a relative humidity of less than 95% a temperature of 0-40 and a wind SPEED of no more than 3m/s. At the same time METEOROLOGICAL conditions also serve as an important basis for ROAD control in the test site. Real time information such as wind SPEED rainfall and visibility provides necessary reference for SITE managers to issue notices on SPEED limits SITE closures and trac restrictions directly aecting the timeliness of ROAD testing safety control. Therefore this article conducts research on the application of METEOROLOGICAL observation SITES in AUTOMOTIVE testing SITES from the construction of METEOROLOGICAL observation SITES METEOROLOGICAL services and abnormal weather ROAD control.
在线阅读 下载PDF
Cyber Resilience through Real-Time Threat Analysis in Information Security
2
作者 Aparna Gadhi Ragha Madhavi Gondu +1 位作者 Hitendra Chaudhary Olatunde Abiona 《International Journal of Communications, Network and System Sciences》 2024年第4期51-67,共17页
This paper examines how cybersecurity is developing and how it relates to more conventional information security. Although information security and cyber security are sometimes used synonymously, this study contends t... This paper examines how cybersecurity is developing and how it relates to more conventional information security. Although information security and cyber security are sometimes used synonymously, this study contends that they are not the same. The concept of cyber security is explored, which goes beyond protecting information resources to include a wider variety of assets, including people [1]. Protecting information assets is the main goal of traditional information security, with consideration to the human element and how people fit into the security process. On the other hand, cyber security adds a new level of complexity, as people might unintentionally contribute to or become targets of cyberattacks. This aspect presents moral questions since it is becoming more widely accepted that society has a duty to protect weaker members of society, including children [1]. The study emphasizes how important cyber security is on a larger scale, with many countries creating plans and laws to counteract cyberattacks. Nevertheless, a lot of these sources frequently neglect to define the differences or the relationship between information security and cyber security [1]. The paper focus on differentiating between cybersecurity and information security on a larger scale. The study also highlights other areas of cybersecurity which includes defending people, social norms, and vital infrastructure from threats that arise from online in addition to information and technology protection. It contends that ethical issues and the human factor are becoming more and more important in protecting assets in the digital age, and that cyber security is a paradigm shift in this regard [1]. 展开更多
关键词 Cybersecurity Information Security Network Security Cyber Resilience Real-time Threat Analysis Cyber Threats Cyberattacks Threat Intelligence Machine Learning Artificial Intelligence Threat Detection Threat Mitigation Risk Assessment Vulnerability Management Incident Response Security Orchestration Automation Threat Landscape Cyber-Physical Systems Critical Infrastructure Data Protection Privacy Compliance Regulations Policy Ethics CYBERCRIME Threat Actors Threat Modeling Security Architecture
在线阅读 下载PDF
REMAINING-LIFETIME AGE-STRUCTURED BRANCHING PROCESSES
3
作者 Ziling CHENG Zenghu LI 《Acta Mathematica Scientia》 2025年第3期1107-1136,共30页
We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the un... We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the unit speed. The models, without or with immigration, are constructed as measure-valued processes by pathwise unique solutions of stochastic equations driven by time-space Poisson random measures. In the subcritical branching case, we give a sufficient condition for the ergodicity of the process with immigration. Two large number laws and a central limit theorem of the occupation times are proved. 展开更多
关键词 branching process remaining lifetime IMMIGRATION stochastic equation ergod-icity occupation time large number law central limit theorem MSC202060J80 60J85 60H15 60F15 60F05
在线阅读 下载PDF
Everything Is Timelessly Connected: Metaphysics, Physics, Consciousness, Spacetime Travel, DNA, and the Dry Bones Prophesy (Ezekiel Ch. 37)
4
作者 Yosef Joseph Segman 《Natural Science》 CAS 2022年第7期265-288,共24页
This paper provides a perception that all things are connected. Starting with the perception of Metaphysics and how matter exists out of total void, complementary matter, or dark matter, the incompleteness of Einstein... This paper provides a perception that all things are connected. Starting with the perception of Metaphysics and how matter exists out of total void, complementary matter, or dark matter, the incompleteness of Einstein relativistic theory. Multi spacetime universes and the jump drive for jumping within and between spacetime universes. Warp drive for space travel. DNA as sequence of momentary frequencies and how it related to Ezekiel’s dry bones prophecy. The outcome of neural patterns as cords of consciousness, consciousness as the collection of all cords of consciousness and the lack of uniqueness of individual consciousness. Finally, all things are cords of consciousness. 展开更多
关键词 VOID COMPLEMENTARY Void Complementary MATTER Complementary Matter METAPHYSICS CONSCIOUSNESS Neural Patterns time timeless Synchronization Order Disorder Universe Group Representation Jump Drive Warp Drive Frequency Phase Fourier Transform Schrödinger Representation Gabor Transform DNA Hologram Virtual<sup>2</sup>
在线阅读 下载PDF
Exploring the impact of mobile device use on mealtime distractions and its consequences for metabolic health:A narrative minireview
5
作者 Muhammad Shahzad Aslam 《World Journal of Clinical Cases》 2025年第17期7-15,共9页
The habitual use of smartphones during meals has become a common behavior,raising concerns about its potential impact on eating habits and metabolic health.The present narrative review investigates how using a smartph... The habitual use of smartphones during meals has become a common behavior,raising concerns about its potential impact on eating habits and metabolic health.The present narrative review investigates how using a smartphone or tablet during meals can cause distractions and negatively affect metabolic health.A comprehensive narrative review was conducted by synthesizing peer-reviewed studies on the interplay between smartphone use during meals,eating behaviors,and metabolic health.Relevant literature was identified through searches in electronic databases and organized thematically to highlight trends and research gaps.By synthesizing evidence from existing literature,this review highlights that smartphone use during meals is associated with increased caloric intake,altered food composition,and disruptions in postprandial metabolic responses.These effects are mediated by reduced meal awareness and psychological distractions,including multitasking.Variability in findings arises from differences in study designs and populations.This review identifies critical research gaps,including the lack of longitudinal studies and the need to explore mechanisms underlying these relationships.By summarizing trends and patterns,this narrative review offers valuable insights into the complex interplay between digital device use,eating habits,and metabolic health,providing a foundation for future research and interventions. 展开更多
关键词 Digital devices Smartphone usage Mealtime behavior Eating habits Postprandial glucose Screen time Dietary patterns Metabolic responses Technological distractions Mobile health
暂未订购
Resource Efficient Hardware Implementation for Real-Time Traffic Sign Recognition
6
作者 Huai-Mao Weng Ching-Te Chiu 《Journal of Transportation Technologies》 2018年第3期209-231,共23页
Traffic sign recognition (TSR, or Road Sign Recognition, RSR) is one of the Advanced Driver Assistance System (ADAS) devices in modern cars. To concern the most important issues, which are real-time and resource effic... Traffic sign recognition (TSR, or Road Sign Recognition, RSR) is one of the Advanced Driver Assistance System (ADAS) devices in modern cars. To concern the most important issues, which are real-time and resource efficiency, we propose a high efficiency hardware implementation for TSR. We divide the TSR procedure into two stages, detection and recognition. In the detection stage, under the assumption that most German traffic signs have red or blue colors with circle, triangle or rectangle shapes, we use Normalized RGB color transform and Single-Pass Connected Component Labeling (CCL) to find the potential traffic signs efficiently. For Single-Pass CCL, our contribution is to eliminate the “merge-stack” operations by recording connected relations of region in the scan phase and updating the labels in the iterating phase. In the recognition stage, the Histogram of Oriented Gradient (HOG) is used to generate the descriptor of the signs, and we classify the signs with Support Vector Machine (SVM). In the HOG module, we analyze the required minimum bits under different recognition rate. The proposed method achieves 96.61% detection rate and 90.85% recognition rate while testing with the GTSDB dataset. Our hardware implementation reduces the storage of CCL and simplifies the HOG computation. Main CCL storage size is reduced by 20% comparing to the most advanced design under typical condition. By using TSMC 90 nm technology, the proposed design operates at 105 MHz clock rate and processes in 135 fps with the image size of 1360 × 800. The chip size is about 1 mm2 and the power consumption is close to 8 mW. Therefore, this work is resource efficient and achieves real-time requirement. 展开更多
关键词 TRAFFIC SIGN Recognition Advanced Driver ASSISTANCE System REAL-time Processing Color Segmentation Connected Component Analysis Histo-gram of Oriented Gradient Support Vector Machine German TRAFFIC SIGN Detection BENCHMARK CMOS ASIC VLSI
在线阅读 下载PDF
Storage time affects the level and diagnostic efficacy of plasma biomarkers for neurodegenerative diseases
7
作者 Lifang Zhao Mingkai Zhang +4 位作者 Qimeng Li Xuemin Wang Jie Lu Ying Han Yanning Cai 《Neural Regeneration Research》 SCIE CAS 2025年第8期2373-2381,共9页
Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is k... Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results. 展开更多
关键词 Alzheimers disease amyloid-β diagnostic ability glial fibrillary acidic protein NEURODEGENERATION neurofilament light chain plasma biomarkers single molecule array storage time tau
暂未订购
Investigation of Excavator Performance Factors in an Open-Pit Mine Using Loading Cycle Time 被引量:1
8
作者 Samwel Victor Manyele 《Engineering(科研)》 2017年第7期599-624,共26页
This study presents the effect of excavator model, loading operation location, shift availability and truck-shovel combination on loading cycle time and productivity of an open-pit mine. The loading cycle time was use... This study presents the effect of excavator model, loading operation location, shift availability and truck-shovel combination on loading cycle time and productivity of an open-pit mine. The loading cycle time was used to assess the material loading system performance which is one of the key components of the total cycle time for material transportation in an open-pit mine. Loading is among the components of cycle time during which material is being handled. The data analyzed?was?collected from a computerized dispatch system at GGM from which 62,000 loading dispatches per month involving several shifts, 14 excavators and 49 trucks were loaded. About 4465 dispatches per excavator and 1276 dispatches per truck were assessed using loading cycle time data for each dispatch for a period of four months (between August and December). Under fixed tonnage loaded and waste type (33 t of non-acid forming waste rock),?it was observed that loading cycle time depends on excavator model, location and truck being loaded. Average cycle times, PDFS?and CDFS of loading cycle time series were used to identify differences in performance under different situations. It was concluded that shift availability for excavators, loading location, excavator model and truck-shovel combinations strongly affect the productivity during loading process in an open-pit mine. 展开更多
关键词 Potentially Acid-Forming (PAF) ROCK Non-Acid FORMING (NAF) ROCK TRUCK Utilization TRUCK Fill-Factor Queuing time LOADING CYCLE time Full and Empty Haul Total CYCLE time Theoretical CYCLE time Non-Productive CYCLE time CYCLE time Performance Ratio
暂未订购
Analysis of Waste-Rock Transportation Process Performance in an Open-Pit Mine Based on Statistical Analysis of Cycle Times Data 被引量:1
9
作者 Samwel Victor Manyele 《Engineering(科研)》 2017年第7期649-679,共31页
In this paper, the performance of a waste rock transportation process in an open pit mine was assessed by using cycle time data. A computerized truck-excavator dispatch system was used to record the cycle times. The p... In this paper, the performance of a waste rock transportation process in an open pit mine was assessed by using cycle time data. A computerized truck-excavator dispatch system was used to record the cycle times. The process was broken into seven steps (or components of the total cycle), durations of which were recorded for a period of 1 month, leading to N = 60,690 data points or dispatches. The open pit mine studied consisted of 12 waste types loaded by 14 excavators and hauled by 49 trucks (at a trucks-to-excavator ratio of 3.5:1) in 75 changing locations. The string-type data was coded using integers to allow a FORTRAN code to extract process performance parameters using statistical analysis. The study established a wide range of parameters including: the waste material generation rate (about 1.73 million t/month, 81% comprising waste rock), truck fill factor, f, total cycle time (Tct), production capacity, theoretical cycle time, non-productive cycle time Tnp, and cycle time performance ratio (CTPR), denoted as Tpr. The factors affecting the process performance include: truck model, excavator model, location (haul distance and road conditions) and material type. For a fixed material type and tonnage, the PDFs of the cycle time components were logarithmic in nature, capable of differentiating performance variations under different factors. It was concluded that the performance of the waste material transportation system in this mine was determined to be acceptable due to mean value of Tpr = 2.432 being closer to unity. Reduction measures were suggested to minimize the cycle time for the process bottlenecks determined from Pareto analysis (that is, full haul, empty haul and loading processes). 展开更多
关键词 Potentially Acid-Forming (PAF) ROCK Non-Acid FORMING (NAF) ROCK TRUCK Utilization TRUCK Fill-Factor Queuing time Loading CYCLE time Full and EMPTY Haul Total CYCLE time Theoretical CYCLE time Non-Productive CYCLE time CYCLE time Performance Ratio
暂未订购
IoT Empowered Early Warning of Transmission Line Galloping Based on Integrated Optical Fiber Sensing and Weather Forecast Time Series Data 被引量:1
10
作者 Zhe Li Yun Liang +1 位作者 Jinyu Wang Yang Gao 《Computers, Materials & Continua》 SCIE EI 2025年第1期1171-1192,共22页
Iced transmission line galloping poses a significant threat to the safety and reliability of power systems,leading directly to line tripping,disconnections,and power outages.Existing early warning methods of iced tran... Iced transmission line galloping poses a significant threat to the safety and reliability of power systems,leading directly to line tripping,disconnections,and power outages.Existing early warning methods of iced transmission line galloping suffer from issues such as reliance on a single data source,neglect of irregular time series,and lack of attention-based closed-loop feedback,resulting in high rates of missed and false alarms.To address these challenges,we propose an Internet of Things(IoT)empowered early warning method of transmission line galloping that integrates time series data from optical fiber sensing and weather forecast.Initially,the method applies a primary adaptive weighted fusion to the IoT empowered optical fiber real-time sensing data and weather forecast data,followed by a secondary fusion based on a Back Propagation(BP)neural network,and uses the K-medoids algorithm for clustering the fused data.Furthermore,an adaptive irregular time series perception adjustment module is introduced into the traditional Gated Recurrent Unit(GRU)network,and closed-loop feedback based on attentionmechanism is employed to update network parameters through gradient feedback of the loss function,enabling closed-loop training and time series data prediction of the GRU network model.Subsequently,considering various types of prediction data and the duration of icing,an iced transmission line galloping risk coefficient is established,and warnings are categorized based on this coefficient.Finally,using an IoT-driven realistic dataset of iced transmission line galloping,the effectiveness of the proposed method is validated through multi-dimensional simulation scenarios. 展开更多
关键词 Optical fiber sensing multi-source data fusion early warning of galloping time series data IOT adaptive weighted learning irregular time series perception closed-loop attention mechanism
在线阅读 下载PDF
Less Screen Time,More Free Time
11
作者 Christine Bedwell 《空中英语教室(初级版.大家说英语)》 2025年第10期44-47,56,共5页
Too much screen time is bad for your brain and body.It can also waste your time.So,try to spend less time on scree ns.Changing habits is not easy,but you can do it.Use an app to track your time on your smartphone.Do y... Too much screen time is bad for your brain and body.It can also waste your time.So,try to spend less time on scree ns.Changing habits is not easy,but you can do it.Use an app to track your time on your smartphone.Do you waste a lot of time on some ofyour phone apps?Take them off or set time limits for them.Less screen time means more free time for other things.Go hiking,visit a museum or try a new hobby.Use your phone less and appreciate life more. 展开更多
关键词 app HABITS free time SMARTPHONE time management screen time BRAIN BODY
暂未订购
An Adaptive Hybrid Metaheuristic for Solving the Vehicle Routing Problem with Time Windows under Uncertainty
12
作者 Manuel J.C.S.Reis 《Computers, Materials & Continua》 2025年第11期3023-3039,共17页
The Vehicle Routing Problem with Time Windows(VRPTW)presents a significant challenge in combinatorial optimization,especially under real-world uncertainties such as variable travel times,service durations,and dynamic ... The Vehicle Routing Problem with Time Windows(VRPTW)presents a significant challenge in combinatorial optimization,especially under real-world uncertainties such as variable travel times,service durations,and dynamic customer demands.These uncertainties make traditional deterministic models inadequate,often leading to suboptimal or infeasible solutions.To address these challenges,this work proposes an adaptive hybrid metaheuristic that integrates Genetic Algorithms(GA)with Local Search(LS),while incorporating stochastic uncertainty modeling through probabilistic travel times.The proposed algorithm dynamically adjusts parameters—such as mutation rate and local search probability—based on real-time search performance.This adaptivity enhances the algorithm’s ability to balance exploration and exploitation during the optimization process.Travel time uncertainties are modeled using Gaussian noise,and solution robustness is evaluated through scenario-based simulations.We test our method on a set of benchmark problems from Solomon’s instance suite,comparing its performance under deterministic and stochastic conditions.Results show that the proposed hybrid approach achieves up to a 9%reduction in expected total travel time and a 40% reduction in time window violations compared to baseline methods,including classical GA and non-adaptive hybrids.Additionally,the algorithm demonstrates strong robustness,with lower solution variance across uncertainty scenarios,and converges faster than competing approaches.These findings highlight the method’s suitability for practical logistics applications such as last-mile delivery and real-time transportation planning,where uncertainty and service-level constraints are critical.The flexibility and effectiveness of the proposed framework make it a promising candidate for deployment in dynamic,uncertainty-aware supply chain environments. 展开更多
关键词 Vehicle routing problem with time windows(VRPTW) hybrid metaheuristic genetic algorithm local search uncertainty modeling stochastic optimization adaptive algorithms combinatorial optimization transportation and logistics robust scheduling
在线阅读 下载PDF
Explicit Approximation Solutions and Proof of Convergence of the Space-Time Fractional Advection Dispersion Equations
13
作者 E. A. Abdel-Rehim 《Applied Mathematics》 2013年第10期1427-1440,共14页
The space-time fractional advection dispersion equations are linear partial pseudo-differential equations with spatial fractional derivatives in time and in space and are used to model transport at the earth surface. ... The space-time fractional advection dispersion equations are linear partial pseudo-differential equations with spatial fractional derivatives in time and in space and are used to model transport at the earth surface. The time fractional order is denoted by β∈ and ?is devoted to the space fractional order. The time fractional advection dispersion equations describe particle motion with memory in time. Space-fractional advection dispersion equations arise when velocity variations are heavy-tailed and describe particle motion that accounts for variation in the flow field over entire system. In this paper, I focus on finding the precise explicit discrete approximate solutions to these models for some values of ?with ?, ?while the Cauchy case as ?and the classical case as ?with ?are studied separately. I compare the numerical results of these models for different values of ?and ?and for some other related changes. The approximate solutions of these models are also discussed as a random walk with or without a memory depending on the value of . Then I prove that the discrete solution in the Fourierlaplace space of theses models converges in distribution to the Fourier-Laplace transform of the corresponding fractional differential equations for all the fractional values of ?and . 展开更多
关键词 ADVECTION-DISPERSION Processes Grünwald-Letnikov Scheme EXPLICIT Difference Schemes Caputo time-Fractional Derivative Inverse RIESZ Potential Random WALK with and without a Memory CONVERGENCE in Distributions Fourier-Laplace Domain
在线阅读 下载PDF
Pinched Material Einstein Space-Time Produces Accelerated Cosmic Expansion
14
作者 M. S. El Naschie 《International Journal of Astronomy and Astrophysics》 2014年第1期80-90,共11页
An instructive analogy between the deformation of a pinched elastic cylindrical shell and the anti-gravity behind accelerated cosmic expansion is established. Subsequently the entire model is interpreted in terms of a... An instructive analogy between the deformation of a pinched elastic cylindrical shell and the anti-gravity behind accelerated cosmic expansion is established. Subsequently the entire model is interpreted in terms of a hyperbolic fractal Rindler space-time leading to the same robust results regarding real energy and dark energy being 4.5% and 95.5% respectively in full agreement with all recent cosmological measurements. 展开更多
关键词 Dark Energy Rindler SPACE-time CARTAN Torsion Pinched Elastic Shells Negative Gravity COSMIC ACCELERATED EXPANSION Fractal SPACE-time Topological Defects Hardys Quantum Entanglement Hawkings Radiation COSSERAT Elasticity
在线阅读 下载PDF
Consideration of Viscoelasticity in Time Step FEM-Based Restraint Analyses of Hardening Concrete
15
作者 Dirk Schlicke Nguyen Viet Tue 《Journal of Modern Physics》 2013年第10期9-14,共6页
Concrete structures may suffer considerable restraint stresses during their hardening period. This is caused by several deformation impacts, especially temperature field changings due to hydration heat and volume chan... Concrete structures may suffer considerable restraint stresses during their hardening period. This is caused by several deformation impacts, especially temperature field changings due to hydration heat and volume changes due to autogenous shrinkage. Mainly affected are massive concrete members, but also the application of new concrete types or the erection of outstanding constructions requires further investigations in this context. 3D-FEM analyses of hydration heat induced temperature development in combination with the well known shrinkage give sufficient results for the deformation impact. The according elastic restraint stresses can be determined with consideration of the concrete’s rising elastic modulus and the restraint degree of the system. But due to duration of the heat flow process, the height of restraint stresses is strongly dependent from the viscoelasticity of the concrete. The viscoelastic effects consist of many components constituted by changing material properties influencing themselves. In practice, different simplified approaches are available for considering this in calculations. Their implementation in time step analyses is not generally admitted and requires expertise. In contrast, present research develops material models needing specific input parameters for every use case. This contribution focuses on a practicable approach considering the superposition of the viscoelastic behaviour of every stress increment in time step FEM analysis. The differentiation between the pure viscoelastic material behaviour (as it is given in the codes for idealistic conditions like creep or relaxation) and the according viscoelastic system response (addicted to the systems variable restraint degree) allows the transfer of this model into practice. As one application example of this approach, the compatibility check and the FEM-based recalculation of the monitoring program of a massive power plant slab will be presented. 展开更多
关键词 VISCOELASTICITY HARDENING Mass Concrete FEM RESTRAINT Analysis time DEPENDANT Material Properties HYDRATION Heat Evolution of Stiffness Quantification of RESTRAINT Stresses In-Situ Measurements Recalculation of Measurement Data
暂未订购
Knowledge Management of Software Productivity and Development Time
16
作者 James A. Rodger Pankaj Pankaj Ata Nahouraii 《Journal of Software Engineering and Applications》 2011年第11期609-618,共10页
In this paper, we identify a set of factors that may be used to forecast software productivity and software development time. Software productivity was measured in function points per person hours, and software develo... In this paper, we identify a set of factors that may be used to forecast software productivity and software development time. Software productivity was measured in function points per person hours, and software development time was measured in number of elapsed days. Using field data on over 130 field software projects from various industries, we empirically test the impact of team size, integrated computer aided software engineering (ICASE) tools, software development type, software development platform, and programming language type on the software development productivity and development time. Our results indicate that team size, software development type, software development platform, and programming language type significantly impact software development productivity. However, only team size significantly impacts software development time. Our results indicate that effective management of software development teams, and using different management strategies for different software development type environments may improve software development productivity. 展开更多
关键词 SOFTWARE Engineering SOFTWARE Metrics FOURTH Generation LANGUAGES CASE TOOLS Field Study TOOLS And Techniques Models And Principles Team Size VOLATILITY DEVELOPMENT Platform And Type Productivity Elapsed DEVELOPMENT time
在线阅读 下载PDF
Research on Estimation of Time Delay Difference in Passive Locating for Impulse Signal
17
作者 徐复 何文翔 +1 位作者 惠俊英 余赟 《Defence Technology(防务技术)》 SCIE EI CAS 2011年第3期167-175,共9页
Analyzed the relation between time delay difference and time delay estimation errors, based on the principles of three-point locating, a reformed threshold method for time delay difference estimation of impulse signal... Analyzed the relation between time delay difference and time delay estimation errors, based on the principles of three-point locating, a reformed threshold method for time delay difference estimation of impulse signals, called as amendment estimation for short, is developed by introducing channel equalization technique to its conventional version, named as direct estimation in this paper, to improve the estimation stability. After inherent relationship between time delay and phase shift of signals is analyzed, an integer period error compensation method utilized the diversities of both contribution share and contribution mode of concerned estimates is proposed under the condition of high precision phase lag estimation. Finally, a cooperative multi-threshold estimation method composed of amendment and direct estimations to process impulse signals with three thresholds is established. In sea trials data tests of passive locating, this method improves the estimation precision of time delay difference efficiently. The experiments verify the theoretical predictions. 展开更多
关键词 information processing technique PASSIVE locating for IMPULSE signal three point positioning time delay DIFFERENCE ESTIMATION amendment ESTIMATION INTEGER period error compensation cooperative MULTI-THRESHOLD ESTIMATION
在线阅读 下载PDF
A novel repetition space-time coding scheme for mobile FSO systems
18
作者 黎明 曹阳 +1 位作者 李书明 杨绍文 《Optoelectronics Letters》 EI 2015年第2期125-129,共5页
Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output (MIMO) free space optics (FSO... Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output (MIMO) free space optics (FSO) communica- tion systems, this paper establishes a channel model for the mobile platform. Based on the combination of Alamouti space-time code and time hopping ultra-wide band (TH-UWB) communications, a novel repetition space-time coding (RSTC) method for mobile 2x2 free-space optical communications with pulse position modulation (PPM) is devel- oped. In particular, two decoding methods of equal gain combining (EGC) maximum likelihood detection (MLD) and correlation matrix detection (CMD) are derived. When a quasi-static fading and weak turbulence channel model are considered, simulation results show that whether the channel state information (CSI) is known or not, the coding sys- tem demonstrates more significant performance of the symbol error rate (SER) than the uncoding. In other words, transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from different antennas. CMD has almost the same effect of signal combining with maximal ratio combining (MRC). However, when the channel correlation increases, SER performance of the coding 2×2 system de- grades significantly. 展开更多
关键词 Atmospheric turbulence Broadband networks Channel capacity Channel state information Codes (symbols) Communication channels (information theory) Fading channels Iterative decoding Maximum likelihood MIMO systems Optical communication Pulse position modulation Radio communication Random errors Signal detection Signal encoding Space time adaptive processing Telecommunication networks time delay Ultra wideband (UWB)
原文传递
Boundary Control Problem of Infinite Order Distributed Hyperbolic Systems Involving Time Lags 被引量:2
19
作者 Bahaa Gaber Mohamed 《Intelligent Control and Automation》 2012年第3期211-221,共11页
Various optimal boundary control problems for linear infinite order distributed hyperbolic systems involving constant time lags are considered. Constraints on controls are imposed. Necessary and sufficient optimality ... Various optimal boundary control problems for linear infinite order distributed hyperbolic systems involving constant time lags are considered. Constraints on controls are imposed. Necessary and sufficient optimality conditions for the Neumann problem with the quadratic performance functional are derived. 展开更多
关键词 BOUNDARY CONTROL (n × n) Hyperbolic Systems time Lags DISTRIBUTED CONTROL Problems NEUMANN Conditions Existence and UNIQUENESS of Solutions Infinite Order Operator
在线阅读 下载PDF
Deep Auto-Encoder Based Intelligent and Secure Time Synchronization Protocol(iSTSP)for Security-Critical Time-Sensitive WSNs
20
作者 Ramadan Abdul-Rashid Mohd Amiruddin Abd Rahman Abdulaziz Yagoub Barnawi 《Computer Modeling in Engineering & Sciences》 2025年第9期3213-3250,共38页
Accurate time synchronization is fundamental to the correct and efficient operation of Wireless Sensor Networks(WSNs),especially in security-critical,time-sensitive applications.However,most existing protocols degrade... Accurate time synchronization is fundamental to the correct and efficient operation of Wireless Sensor Networks(WSNs),especially in security-critical,time-sensitive applications.However,most existing protocols degrade substantially under malicious interference.We introduce iSTSP,an Intelligent and Secure Time Synchronization Protocol that implements a four-stage defense pipeline to ensure robust,precise synchronization even in hostile environments:(1)trust preprocessing that filters node participation using behavioral trust scoring;(2)anomaly isolation employing a lightweight autoencoder to detect and excise malicious nodes in real time;(3)reliability-weighted consensus that prioritizes high-trust nodes during time aggregation;and(4)convergence-optimized synchronization that dynamically adjusts parameters using theoretical stability bounds.We provide rigorous convergence analysis including a closed-form expression for convergence time,and validate the protocol through both simulations and realworld experiments on a controlled 16-node testbed.Under Sybil attacks with five malicious nodes within this testbed,iSTSP maintains synchronization error increases under 12%and achieves a rapid convergence.Compared to state-ofthe-art protocols like TPSN,SE-FTSP,and MMAR-CTS,iSTSP offers 60%faster detection,broader threat coverage,and more than 7 times lower synchronization error,with a modest 9.3%energy overhead over 8 h.We argue this is an acceptable trade-off for mission-critical deployments requiring guaranteed security.These findings demonstrate iSTSP’s potential as a reliable solution for secure WSN synchronization and motivate future work on large-scale IoT deployments and integration with energy-efficient communication protocols. 展开更多
关键词 time-sensitive wireless sensor networks(TS-WSNs) secure time synchronization protocol trust-based authentication autoencoder model deep learning malicious node detection Internet of Things energyefficient communication protocols
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部