39 research outputs found

    Боротьба української громадськості за розв’язання мовної проблеми в народних школах (друга половина ХІХ – початок ХХ ст.)

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    (uk) У статті висвітлено маловідомі сторінки історії боротьби української громадськості за розв’язання мовної проблеми в народних школах у другій половині ХІХ – на початку ХХ ст. Важливу роль у цих змаганнях відіграли педагогічні з’їзди та з’їзди отців-законовчителів.(en) The article covers the little-known pages of the history of the struggle of the Ukrainian Community for the decision of the language problem in national schools in the second half of the 19th century and at the beginning of the 20th century. Pedagogical congresses played an important part in those contests

    Estimation of the flux at 1450MHz of OB stars for FAST and SKA

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    Radio observation is crucial to understanding the wind mechanism of OB stars but very scarce. This work estimates the flux at 1450MHz (S1.4GHzS_{\rm 1.4GHz}) of about 5,000 OB stars identified by the LAMOST spectroscopic survey and confirmed by the Gaia astrometric as well as astrophysical measurements. The calculation is performed under the free-free emission mechanism for wind with the mass loss rate derived from stellar parameters. The estimated S1.4GHzS_{\rm 1.4GHz} distributes from 101110^{-11}Jy to 10310^{-3}Jy with the peak at about 10810^{-8}Jy. This implies that the complete SKA-II can detect more than half of them, and some tens of objects are detectable by FAST without considering source confusion. An array of FAST would increase the detectable sample by two orders of magnitude.Comment: 15 pages. 8 figure

    Fatigue and symptom-based clusters in post COVID-19 patients: a multicentre, prospective, observational cohort study

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    Background: In the Netherlands, the prevalence of post COVID-19 condition is estimated at 12.7% at 90–150 days after SARS-CoV-2 infection. This study aimed to determine the occurrence of fatigue and other symptoms, to assess how many patients meet the Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) criteria, to identify symptom-based clusters within the P4O2 COVID-19 cohort and to compare these clusters with clusters in a ME/CFS cohort. Methods: In this multicentre, prospective, observational cohort in the Netherlands, 95 post COVID-19 patients aged 40–65 years were included. Data collection at 3–6 months after infection included demographics, medical history, questionnaires, and a medical examination. Follow-up assessments occurred 9–12 months later, where the same data were collected. Fatigue was determined with the Fatigue Severity Scale (FSS), a score of ≥ 4 means moderate to high fatigue. The frequency and severity of other symptoms and the percentage of patients that meet the ME/CFS criteria were assessed using the DePaul Symptom Questionnaire-2 (DSQ-2). A self-organizing map was used to visualize the clustering of patients based on severity and frequency of 79 symptoms. In a previous study, 337 Dutch ME/CFS patients were clustered based on their symptom scores. The symptom scores of post COVID-19 patients were applied to these clusters to examine whether the same or different clusters were found. Results: According to the FSS, fatigue was reported by 75.9% of the patients at 3–6 months after infection and by 57.1% of the patients 9–12 months later. Post-exertional malaise, sleep disturbances, pain, and neurocognitive symptoms were also frequently reported, according to the DSQ-2. Over half of the patients (52.7%) met the Fukuda criteria for ME/CFS, while fewer patients met other ME/CFS definitions. Clustering revealed specific symptom patterns and showed that post COVID-19 patients occurred in 11 of the clusters that have been observed in the ME/CFS cohort, where 2 clusters had > 10 patients. Conclusions: This study shows persistent fatigue and diverse symptomatology in post COVID-19 patients, up to 12–18 months after SARS-CoV-2 infection. Clustering showed that post COVID-19 patients occurred in 11 of the clusters that have been observed in the ME/CFS cohort

    Heavy-Duty Vehicle Platooning : Modeling and Analysis

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    Coupled with the growth of world economy, the demand for freight transport has escalated and will continue to do so. As the traffic intensity increases, the pressure on infrastructure, energy usage and environment becomes higher than ever. Meanwhile, the number of traffic accidents is also increasing year by year as a result. Heavy-duty vehicle (HDV) platooning makes a group of HDVs driving closely after each other.It is one potential solution to improve transport efficiency, traffic safety and fuel economy. Even though there have been extensive studies on the platooning system and corresponding fuel saving, some of the research areas, such as coordination strategies of platooning, platoon operations and the impacts of HDV platooning on trafficflow are still left open. Under a futuristic scenario where a large number of HDVswill be operating in one or several platoons on highway, how to group HDVs intoa platoon and how to select spacing policies for HDV platooning are essential forautomobile manufacturers, fleet operators and transport planners. Therefore, theformation strategies and operations of HDV platoons, as well as the impacts of HDVplatooning on traffic flow have to be carefully investigated. This thesis presents contributions to the modeling of HDV platooning and simulationof HDV platoon operations. The focus lies mainly on analytical formulation ofspeed-density relation of mixed traffic flow and development of simulation frameworkfor study of HDV platooning. On the one hand, a three-regime speed-density relationis proposed to describe the mixed traffic flow consisting of HDVs and passengercars. The proposed speed-density relation incorporates percentage of HDVs, trafficdensity and spacing policy of HDV platoons as input variables and delivers aggregatehighway velocity as output. By comparing the traffic throughput of no HDV platooningscenario, grouping HDVs into platoon using constant vehicle spacing policy orconstant time gap policy results in significant improvement in highway capacity. On the other hand, a simulation framework is developed for implementation of differentHDV platoon operations. The platoon formation of two HDVs and disaggregation ofa five-HDV platoon at off-ramp are simulated on a two-lane highway. The simulationoutcomes show that HDV platoon formation is more favorable in light and mediumtraffic; disaggregation of a long HDV platoon at off-ramp improves the averagespeed of passenger vehicles considerably at high traffic flow rate.QC 20160210</p

    Heavy-Duty Vehicle Platooning : Modeling and Analysis

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    Coupled with the growth of world economy, the demand for freight transport has escalated and will continue to do so. As the traffic intensity increases, the pressure on infrastructure, energy usage and environment becomes higher than ever. Meanwhile, the number of traffic accidents is also increasing year by year as a result. Heavy-duty vehicle (HDV) platooning makes a group of HDVs driving closely after each other.It is one potential solution to improve transport efficiency, traffic safety and fuel economy. Even though there have been extensive studies on the platooning system and corresponding fuel saving, some of the research areas, such as coordination strategies of platooning, platoon operations and the impacts of HDV platooning on trafficflow are still left open. Under a futuristic scenario where a large number of HDVswill be operating in one or several platoons on highway, how to group HDVs intoa platoon and how to select spacing policies for HDV platooning are essential forautomobile manufacturers, fleet operators and transport planners. Therefore, theformation strategies and operations of HDV platoons, as well as the impacts of HDVplatooning on traffic flow have to be carefully investigated. This thesis presents contributions to the modeling of HDV platooning and simulationof HDV platoon operations. The focus lies mainly on analytical formulation ofspeed-density relation of mixed traffic flow and development of simulation frameworkfor study of HDV platooning. On the one hand, a three-regime speed-density relationis proposed to describe the mixed traffic flow consisting of HDVs and passengercars. The proposed speed-density relation incorporates percentage of HDVs, trafficdensity and spacing policy of HDV platoons as input variables and delivers aggregatehighway velocity as output. By comparing the traffic throughput of no HDV platooningscenario, grouping HDVs into platoon using constant vehicle spacing policy orconstant time gap policy results in significant improvement in highway capacity. On the other hand, a simulation framework is developed for implementation of differentHDV platoon operations. The platoon formation of two HDVs and disaggregation ofa five-HDV platoon at off-ramp are simulated on a two-lane highway. The simulationoutcomes show that HDV platoon formation is more favorable in light and mediumtraffic; disaggregation of a long HDV platoon at off-ramp improves the averagespeed of passenger vehicles considerably at high traffic flow rate.QC 20160210</p

    Antenna Optimization in Long-Term Evolution Networks

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    The aim of this master thesis is to study algorithms for automatically tuning antenna parameters to improve the performance of the radio access part of a telecommunication network and user experience. There are four dierent optimization algorithms, Stepwise Minimization Algorithm, Random Search Algorithm, Modied Steepest Descent Algorithm and Multi-Objective Genetic Algorithm to be applied to a model of a radio access network. The performances of all algorithms will be evaluated in this thesis. Moreover, a graphical user interface which is developed to facilitate the antenna tuning simulations will also be presented in the appendix of the report

    Fast Algorithm for Planning Optimal Platoon Speeds on Highway

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    To meet policy requirements on increased transport energy eciency and reduced emissions, smart control and management of vehicles and eets have become important for the development of eco-friendly intelligent transportation systems (ITS). The emergence of new information and communication technologies and their applications, particularly vehicle to vehicle and vehicle-to-infrastructure communication, facilitates the implementation of autonomous vehicle concepts, and meanwhile serves as an eective means for control of vehicle eet by continuously providing support and guidance to drivers. While convoy driving of trucks by longitudinal automation could save 5-15% of fuel consumption due to the reduction of airdrag resistance, this study attempts to investigate the energy saving potential of truck platoons by intelligent speed planning. Assuming that real-time trac information is available because of communication, an ecient speed control algorithm is proposed based on optimal control theory. The method is faster than the conventional dynamic programming approach and hence applied in the study to analyze energy saving potential of simple platoon operations including acceleration and deceleration. The numerical result shows signicant improvement on energy saving due to speed planning during platooning. It can be further applied for more complex platooning operations.QC 20141107</p

    Study of the Platooning Fuel Efficiency under ETSI ITS-G5 Communications

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    In this paper we evaluate the performance of platoon enabled by contemporary ITS-G5 vehicular communications through a number of simulation experiments. We assess platooning fuel consumption performance under two communication setups and estimate the potential influence of the communication system on the efficiency of the platooning. We also make an attempt to transform our results on platoon fuel efficiency into potential cost reduction gain. Our study shows that platooning fuel-efficiency may vary depending on the communication setup.Funding: the Knowledge Foundation, Sweden in cooperation with Volvo GTT, Volvo Cars, Scania, Kapsch TrafficCom and Qamcom Research &amp; Technology. It is also supported by the National ITS Postgraduate School (NFITS), Sweden.ACDC: Autonomous Cooperative Driving: Communications Issue

    Long-Life Fatigue of Carburized 12Cr2Ni Alloy Steel: Evaluation of Failure Characteristic and Prediction of Fatigue Strength

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    In this study, the fatigue failure behaviors of carburized 12Cr2Ni alloy steel were examined in the long-life regime between 104 and 108 cycles with about 100 Hz under R = 0. Results showed that this alloy steel exhibited the double S-N characteristics with surface failure and interior failure. From a statistical point of view, the correlation coefficient further proved that the fine granular area (FGA) governed the fatigue performance of carburized 12Cr2Ni alloy steel. Based on the generalized extreme values (GEV) distribution and test data, the predicted maximum defect size was about 23.4 &#956;m. Considering the effect of tensile limit, material hardness, and crack size characteristics, the fatigue strength prediction model under stress ratio of 0 could be established. The predicted fatigue limit for carburized 12Cr2Ni alloy steel at 108 cycles under R = 0 was 507.86 MPa, and the prediction error of fatigue limit was within 0.04. Therefore, the results were extremely accurate
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