课程文献中心 更多>>

关键词： Smart environments   Edge computing   Video analytics   Optimization   Internet-of-things   RECOGNITION   ANALYTICS  

摘要： Surveillance videos in smart environments have become commodities nowadays, which enable many novel applications, including various video analytics that turn videos into semantic results. In addition to live feeds, surveillance videos may be saved in a storage server for on-demand user-defined queries in the future. Different from on-demand video streaming servers, whose design objective is to maximize the user-perceived video quality, a surveillance video storage server has limited space and must retain as much information as possible while reserving sufficient space for incoming videos. In this article, we design, implement, optimize, and evaluate a multi-level feature driven storage server for diverse-scale smart environments, which can be buildings, campuses, communities, and cities. We focus on the design and implementation of the storage server and solve two key research problems in it, namely: (i) efficiently determining the information amount of incoming videos and (ii) intelligently deciding the qualities of videos to be kept. In particular, we first analyze the videos to derive approximate information amount without overloading our storage server. This is done by formally defining the information amount based on multi-level (semantic and visual) features of videos. We then leverage the information amounts to determine the optimal downsampling approach and target quality level of each video clip to save the storage space, while preserving as much information amount as possible. We rigorously formulate the above two research problems into mathematical optimization problems, and propose optimal, approximate, and efficient algorithms to solve them. Besides a suite of optimization algorithms, we also implement our proposed system on a smart campus testbed at NTHU, Taiwan, which consists of eight smart street lamps. The street lamps are equipped with a wide spectrum of sensors, network devices, analytics servers, and a storage server. We compare the performance

关键词： FRAMEWORK   PARTICIPATION   IMPACT  

摘要： This article reports on the barriers and drivers of online micro-course (oMC) professional development in a Middle East college. Semi-structured interviews with teachers yield a rich description of their learning experiences. The findings demonstrate the significance of identity and agency in online professional development: course accessibility advantages, valuable reflexive opportunities and successful practice shifts act as drivers to engagement and bolster identities. Meanwhile, impediments to oMC acceptance are evidenced in constrained peer collaboration, misaligned faculty and organisational interests and forced compliance which restrict agency and marginalise teacher identities. An original, inductive model to guide future research is also presented. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： Giant sawflies   Morphological evolution   Intrasexual competition   Mimicry patterns  

摘要： Cimbicidae is a small family of Tenthredinoidea, containing the largest extant true sawflies. Body length variation across the family is mapped on an existing phylogeny, and some potential drivers of body size increase are explored: intrasexual competition between males, and mimicry patterns. Body length varies substantially within Cimbicidae, the largest species being found within the subfamily Cimbicinae. The smallest species occur in Corynidinae; this subfamily has experienced an overall decrease in body size. Initially, body size increase in Cimbicinae is correlated with males becoming larger than females, increase in relative mandible size in both sexes but especially in males, and increased hind femur width/length ratio in males only. Relative mandible size decreases in Cimbex spp. + Odontocimbex and hind femur width/length in male Leptocimbex spp., respectively. The record sizes obtained in Cimbex spp. + Odontocimbex are the result of a further increase in body size, coupled with increase in hind femur width/length ratio in males. Black and yellow body colouration and other potential mimicry patterns are observed in a number of genera of Cimbicinae, but are probably not ground plan features of the subfamily. Outside Cimbicinae, black and yellow body colouration is most frequent in Corynidinae, but it cannot be decided if it is a ground plan trait of this subfamily. Intrasexual competition seems to be more likely to have influenced size increase in Cimbicinae than adaptations to mimicry.

关键词： Climate change   Cumulative effects   Land use   Northern fennoscandia   Practitioner knowledge   Reindeer husbandry   RANGIFER-TARANDUS-TARANDUS   SEMI-DOMESTICATED REINDEER   PUBLIC-PARTICIPATION GIS   INFRASTRUCTURE DEVELOPMENT   WINTER PASTURES   WILD REINDEER   HUSBANDRY   IMPACTS   SNOW   GOVERNANCE  

摘要： Drivers of change in the reindeer management system are rather well-known. But when developing the gover-nance to support the traditional livelihoods, it is crucial to understand also practitioner perceptions. Systematic research on these is lacking. We analyzed the land-use and climate related drivers within the reindeer man-agement area (RMA) in Finland, and, using a perception geography approach, studied the herder perceptions towards these. We conducted an on-site questionnaire survey with herders from 51 herding districts. Factors directly affecting the welfare of reindeer were perceived as crucial by herders, for example basal icing affecting the forage availability, and land-use related factors limiting the seasonal pasture access. Perceptions of herders on biophysical factors were rather homogeneous. The regional heterogeneities in perceptions towards land-use related factors could be explained by spatial differences in land-use and varying herding traditions. Cumulative land-use impacts raised particular concerns. Our approach can be utilized in the co-planning of the northern land-use and more widely in the co-management of natural resources.

关键词： epiGenetic algorithm   Smart mobility   LED panel   Travel time   Greenhouse gas emissions   Fuel consumption   ALGORITHMS  

摘要： Traffic congestion is one of the main concerns of citizens living in big cities. In this article we propose a novel system, called Yellow Swarm, with the aim of improving road traffic at a low cost and easy implementation by using a set of LED panels placed throughout the city in order to spread road traffic over its streets. The system is optimally configured by a new epigenetic algorithm which calculates the time slots for each suggested detour shown in the panels. Yellow Swarm was tested on three scenarios of the city of Malaga, Spain, using the real city layout and actual traffic flows calculated by our flow generator algorithm with data published by the city's authorities. Our results show shorter average travel times (up to 19 s) and a reduction of greenhouse gas emissions (up to 4.5%) and fuel consumption (up to 1.6%), which have been achieved without increasing the maximum travel times (reduced by 205 s). Yellow Swarm, as a distributed traffic management system in the city, represents a major improvement that benefits drivers on long trips by reducing travel times and preventing traffic jams. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Blockchain   IPFS   Covert communication   Image steganography   Plain text steganography  

摘要： The secret information may be compromised for the lack of security and concealment in conventional covert communication. Blockchain is a suitable platform for establishing covert channels to protect the secret information, due to its features of anti-tamper, anti-forgery, anonymity, and information synchronization. However, the cost of storing large files in the blockchain is too high. To solve the above problems, we propose a double steganography model which combines blockchain and interplanetary file system (IPFS) in this paper. The model consists of two parts: image steganography and plain text steganography. In image steganography, the model embeds secret information into the original image using the least significant bit (LSB) algorithm based on RSA encryption. Then the image is stored in IPFS that returns the hash value. In plain text steganography, the model embeds the hash value into plain text files by the whitespace method based on partial order. Then those files are transmitted through blockchain network covert channels. Any node can obtain the files as the receiver. But only the trusted party can extract the secret information through the inverse process of embedding. Experimental results show that the proposed model has high performance of anti-detection and guarantees the concealment of communication.

关键词： Carbon cycle   Climate change   Global warming   Greenhouse gas emission   Natural wetland   Wetland management   METROPOLITAN RIVER NETWORK   FRESH-WATER WETLANDS   METHANE EMISSIONS   NITROUS-OXIDE   TEMPORAL VARIATIONS   COASTAL WETLANDS   CARBON BALANCE   CH4 EMISSIONS   RICE PADDIES   FLUXES  

摘要： Whether natural wetlands serve as the source or sink of greenhouse gases (GHGs) remains uncertain. Wetlands in China are diverse in type and abundant in quantity and differ greatly in spatial distribution, environmental conditions, and GHG fluxes. However, few studies focused on the differences in GHG emissions from different types of natural wetlands. Here, we adopted strict data collection criteria to create comprehensive and detailed datasets of fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from the marsh, coastal, lake, and river wetlands in China, and relevant environmental variables. Our study synthesized 265 field observations on GHGs that lasted at least one year (covering both the growing season and non-growing season) from 109 studies, among which CO2 measurements using the opaque chamber method were not included for eliminating the influence of absence of photosynthesis on net CO2 accounting. We found that CH4 contributed the largest warming effect among the three types of GHGs, and coastal and river wetlands respectively acted as the mitigators and motivators of global warming among the four types of wetlands. Correlation and regression analyses suggested that geographic location, soil moisture and organic carbon, and contents of nitrogen, phosphorus, and dissolved oxygen jointly drove wetland GHG fluxes. The comprehensive global warming potential of Chinese natural wetlands was estimated as 427 Tg CO2-equivalents year(-1), which might result from increased wetland drainage, reclamation, and external nutrient inputs. This study highlights the incorporation of the full year-round GHG monitoring data without using opaque chambers to measure CO2 flux when extrapolating net GHG emissions and gives implications for natural wetland management and global warming mitigation strategies.

关键词： Atmospheric water balance   CORDEX-CORE   Climate change   RegCM4   CLIMATE-CHANGE PROJECTIONS   LOW-LEVEL JET   SOUTH-AMERICA   HYDROLOGICAL CYCLE   EUROPEAN CLIMATE   CLARIS-LPB   MODEL   TEMPERATURE   PARAMETERIZATION   SIMULATIONS  

摘要： This study evaluates the projected changes in the atmospheric water budget and precipitation under the RCP8.5 scenario over two CORDEX-CORE domains: South America (SAM) and Europe (EUR). An ensemble of five twenty-first century projections with the Regional Climate Model version 4 (RegCM4) and their driving Global Climate Models (GCMs) are analyzed in terms of the atmospheric water budget terms (precipitation, P; evapotranspiration, ET; and moisture flux convergence, C). Special focus is on four subregions: Amazon (AMZ), La Plata basin (LPB), Mid-Europe (ME) and Eastern Europe (EA). The precipitation change signal in SAM presents a dipole pattern, i.e. drier conditions in AMZ and wetter conditions in LPB. Over the two European regions a seasonality is evident, with an increase of similar to 25% in precipitation for DJF and a decrease of similar to 35% in JJA. The atmospheric water budget drivers of precipitation change vary by region and season. For example, in DJF the main drivers are related to the large-scale moisture flux convergence, while in JJA over the AMZ atmospheric moisture flux convergence plays only a minor role and local processes dominate. For JJA in the GCMs the high values of the residual term do not allow us to assess which mechanisms drive the precipitation change signal over the AMZ and LPB, respectively. Same conclusions are found for the RegCM4 JJA simulations over the LPB and EA. This points to the importance of the spatial resolution of climate simulations and the role of parameterization schemes in climate models. Our work illustrates the usefulness of analyzing regional water budgets for a better understanding of precipitation change patterns around our globe.

关键词： NDE 4   0   Use cases   Value proposition   Advanced NDE   Future of NDE   Automation   NDT 4   0   Industry 4   0   Cyber-physical loop   Digital twin   Digital thread   Digital weave   IIoT   Industrial revolution  

摘要： Across so many industries, non-destructive evaluation has proven its worth time and again through quality and safety assurance of valuable assets. Yet, over time, it became underappreciated in business decisions. In most cases, the data gathered by NDT is used for quality assurance assessments resulting in binary decisions. And we seem to miss out on value of the information content of NDE which goes way deeper and can help other stakeholders: such as engineering, management, inspectors, service providers, and even regulators. Some of those groups might not even be aware of the benefits of NDE data and its digitalization. Unfortunately, the NDE industry typically makes the data access unnecessarily difficult by proprietary interfaces and data formats. Both those challenges need to be addressed now by the NDE industry. The confluence of NDE and Industry 4.0, dubbed as NDE 4.0, provides a unique opportunity for the NDE/NDT Industry to not only readjust the value perception but to gain new customer groups through a broad set of value creation activities across the ecosystem. The integration of NDE into the Cyber-Physical Loop (including IIoT and Digital Twin) is the chance for the NDE industry to now shift the perception from a cost center to a value center. This paper provides an overview of the NDE ecosystem, key value streams, cyber-physical loops that create value, and a number of use cases for various stakeholders in the ecosystem.