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A Review on Challenges in DC Microgrid Planning and Implementation

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Journal of Modern Power Systems and Clean Energy 2023年第5期11卷 1375-1395页

作者： Kolampurath Jithin Puthan Purayil Haridev Nanappan Mayadevi Raveendran Pillai Harikumar Valiyakulam Prabhakaran Mini IEEE Department of Electrical Engineering College of Engineering TrivandrumAPJ Abdul Kalam Technological University(APJAKTU)ThiruvananthapuramKeralaIndia Tata consultancy Services(TCS) KochiKeralaIndia

DC microgrids are gaining more attention with the increased penetration of various DC sources such as solar photovoltaic systems, fuel cells, batteries, etc., and DC loads. Due to the rapid integration of these components into the existing power system, the importance of DC microgrids has reached a salient point. Compared with conventional AC systems, DC systems are free from synchronization issues, reactive power control, frequency control, etc., and are more reliable and ***, many challenges need to be addressed for utilizing DC power to its full potential. The absence of natural current zero is a significant issue in protecting DC systems. In addition,the stability of the DC microgrid, which relies on inertia, needs to be considered during system design. Moreover, power quality and communication issues are also significant challenges in DC microgrids. This paper presents a review of various value streams of DC microgrids including architectures, protection schemes, power quality, inertia, communication, and economic operation. In addition, comparisons between different microgrid configurations, the state-of-the-art projects of DC microgrid, and future trends are also set forth for further studies.

关键词： Architecture communication DC microgrid economic operation inertia protection power quality

Do not let precision medicine be kidnapped

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Frontiers of Medicine 2015年第4期9卷 512-513页

作者： Zhiping Yang consultancy Program Center Chinese Academy of Engineering Beijing 100088 China Tsinghua University School of Medicine Beijing 100084 China

Obama＇s precision medicine initiative made the medical community boil over after the initiative＇s release. Precision medicine has been advocated by the majority of scientists and doctors. However, some experts have questioned this concept. This article does not oppose precision medicine. However, the incentive of vigorously promoting precision medicine at present is a concern.

关键词： precision medicine personalized medicine genomics

Understanding Hydrogen Redistribution During Steel Casting,and Its Effective Extraction by Thermally Induced Up-Hill Diffusion

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Journal of Iron and Steel Research International 2011年第S1期18卷 159-163页

作者： Gaude-fugarolas Daniel Independent Research and consultancy in Physical Metallurgy and Engineering c/.Alcalde Joan Batalla 408340 Vilassar de MarSpain

The severe loss of ductility caused by hydrogen in high strength steels has been the object of intense research during *** of the high mobility of hydrogen once has entered the metal,even in comparison with other interstitial atoms like carbon and nitrogen,a rigorous description of hydrogen fluxes during manufacturing of steel components is considered to be essential.A physical model of interstitial element diffusion is used to study the fluxes of hydrogen during solidification and cooling of cast *** particular,the present model contemplates diffusion in its most comprehensive description,i.e.,atom diffusion is driven by a reduction of the Gibbs energy of the ***,it is only considered the case in which diffusion occurs to reduce the concentration gradient of an element at constant matrix composition and ***,in a more general view,and as was proven by Darken (1949),diffusion may occur even up-hill the composition gradient as long it still leads to a reduction of Gibbs energy in the *** diffusion occurs due to a temperature gradient,it has been referred to as thermal diffusion or Ludwig-Soret *** model presented incorporates physical description of thermal agitation and atom mobility of interstitial elements,the influence of temperature gradients,solubility and saturation of the interstitial elements as function of temperature and matrix phases,as well as the kinetics of degassing at high *** application of this model shows how hydrogen localizes in some regions of the component to a degree that depends on manufacturing conditions and where it may reach concentrations well beyond the initial average concentration in the *** model describes as well how the FCC to BCC phase transformation may drive hydrogen concentration beyond supersaturation,due to the disparate capability of these phases to dissolve *** the other hand,this study has also enabled the development of a method for the

关键词： hydrogen diffusion embrittlement extraction

A Switch Agent for Wireless Sensor Nodes with Dual Interfaces: Implementation and Evaluation

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Tsinghua Science and Technology 2012年第5期17卷 586-598页

作者： Tao Zheng Sridhar Radhakrishnan Venkatesh Sarangan School of Computer Science University of Oklahoma Norman OK 73019 USA Chennai Innovation Labs Tata Consultancy Services Chennai 600086 India

Data generation in wireless sensor networks could be bursty as it is dictated by the presence or absence of events of interest that generate these data. While conventional sensor nodes possessed only one radio interface, next generation sensor nodes are expected to have two （possibly more） radio interfaces, each with different ranges, capacities, and power consumptions. Equipping sensor nodes with dual radios has its own benefits and can be quite useful in handling bursty traffic while at the same time satisfying the application＇s delivery requirements. In this paper, we propose an adaptive interface switch agent that intelligently selects the interface to be used for data transmission at a sensor node based on the data burst length or end-to-end delay while taking into consideration power consumption and throughput. The proposed work generalizes earlier works in this area to enable both the source nodes and intermediate data forwarding nodes to initiate the activation of high power radios so that they can be utilized to a higher degree for converge-cast communication. We have performed extensive simulations with sensor nodes containing both IEEE 802.15.4 and IEEE 802.11 compatible radios. Our simulation results indicate that the switch agent yields throughput, delay, and packet delivery ratio comparable to the higher bandwidth interface alone, without incurring much energy wastage.

关键词： wireless sensor networks dual radios switch agent IEEE 802.11 IEEE 802.15.4

Importance of Adaptive Photometric Augmentation for Different Convolutional Neural Network

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Computers, Materials & Continua 2022年第9期72卷 4433-4452页

作者： Saraswathi Sivamani Sun Il Chon Do Yeon Choi Dong Hoon Lee Ji Hwan Park AI Reliability Lab ThinkforBL Consultancy ServicesGangnamSeoulKorea Department of Biosystems Engineering Chungbuk National UniversityCheongju-siChungcheongbuk-do28644Korea

Existing segmentation and augmentation techniques on convolutional neural network(CNN)has produced remarkable progress in object ***,the nominal accuracy and performance might be downturned with the photometric variation of images that are directly ignored in the training process,along with the context of the individual CNN *** this paper,we investigate the effect of a photometric variation like brightness and sharpness on different *** observe that random augmentation of images weakens the performance unless the augmentation combines the weak limits of photometric *** approach has been justified by the experimental result obtained from the PASCAL VOC 2007 dataset,with object detection CNN algorithms such as YOLOv3(You Only Look Once),Faster R-CNN(Region-based CNN),and SSD(Single Shot Multibox Detector).Each CNN model shows performance loss for varying sharpness and brightness,ranging between−80%to 80%.It was further shown that compared to random augmentation,the augmented dataset with weak photometric changes delivered high performance,but the photometric augmentation range differs for each ***,we discuss some research questions that benefit the direction of the *** results prove the importance of adaptive augmentation for individual CNN model,subjecting towards the robustness of object detection.

关键词： Object detection photometric variation adaptive augmentation convolutional neural network

How do greenhouse gas emissions vary with biofertilizer type and soil temperature and moisture in a tropical grassland?

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Pedosphere 2020年第5期30卷 607-617页

作者： Abmael da Silva CARDOSO Juliana Bega JUNQUEIRA Ricardo Andrade REIS Ana Claudia RUGGIERIAnimal Science Departament College of Agricultural and Veterinarian SciencesSao Paulo State UniversityJaboticabal 14884-900(Brazil) Kenji Agricultural and Environmental consultancy Ribeirdo Preto 14010-079(Brazil)

Greenhouse gases are known to play an important role in global *** this study,we determined the effects of selected soil and climate variables on nitrous oxide(N2O),methane(CH4),and carbon dioxide(CO2)emissions from a tropical grassland fertilized with chicken slurry,swine slurry,cattle slurry,and cattle *** N2O emissions did not differ between treatments and varied from 29.26 to 32.85 mg N m^-***,cumulative CH4 emissions were not significantly different among the treatments and ranged from 6.34 to 57.73 mg CH4 m^-*** and compost application induced CO2 emissions that were significantly different from those in the control *** CH4 conversion factors measured were 0.21%,1.39%,4.39%,and 5.07%for cattle compost,chicken slurry,swine slurry,and cattle slurry,respectively,differing from the recommendations of the Intergovernmental Panel on Climate Change(IPCC).The fraction of added Nemitted as N2O was 0.39%,which was lower than the IPCC default value of 2%.Our findings suggest that N2O emissions could be mitigated by replacing synthetic fertilizer sources with either biofertilizer or *** results indicate the following:N2O emission was mainly controlled by soil temperature,followed by soil moisture and then soil NH^"content;CH4 fluxes were mainly controlled by soil moisture and chamber headspace temperature;and CO2 fluxes were mainly controlled by chamber headspace temperature and soil moisture.

关键词： emission factor methane conversion factor methane oxidation methane production capacity slurry fertilizer soil moisture

A Comparative Study of Groundwater between Geological Groups of Southern Benue Trough,Nigeria Using Modelling Approach

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Journal of Environmental & Earth Sciences 2021年第2期3卷 72-86页

作者： Moses Oghenenyoreme Eyankware Philip Njoku Obasi Christoper Ogwah Department of Geology Ebonyi State UniversityEbonyi StateNigeria Geomoses consultancy Limited Warri Delta StateNigeria

Groundwater studies were carried out between two geological groups to evaluate factors that influences groundwater *** achieve this,30 groundwater samples were *** such as pH,Electrical Conductivity(Ec),Total Dissolved Solids(TDS),Total Hardness(TH),and hydrochemical characteristics(Na^(2+),K^(+),Ca^(2+),Mg^(2+),HCO_(3)^(¯),NO_(3)^(¯),Cl^(¯),CO_(2)^(3¯),and SO_(4)^(2¯))of groundwater were *** revealed that the pH value for Asu River Group ranges from 5.3 to 7.5,and that of Eze Aku Group ranges from 4.1 to *** was observed that areas around the mines had low pH *** results that were obtained were interpreted using various hydrogeochemical *** plots reflected that groundwater within the two geological groups fell within Ca˗Mg˗SO_(4) and Ca˗Mg˗*** from End˗member plots showed that 96%of groundwater samples analyzed were categorized under carbonate weathering,4%fell silicate *** plots revealed that interactions between groundwater and surrounding host rocks are mostly the main processes responsible for chemical characteristics of groundwater,Diamond field plots suggested that groundwater within the study were categorized to be high in Ca+Mg&SO_(4)+Cl,the plot of Ca^(2+)/(HCO_(3)^(¯)+SO_(4)^(2¯))against Na^(+)/Cl^(¯)revealed that groundwater was considered to be within the natural state for the two *** plot of TDS against TH showed that groundwater is classified as soft *** study revealed there was no significant difference between factors that influence groundwater within the two geological.

关键词： Weathering Ion exchange Group Groundwater Nigeria

Scour and liquefaction issues for anchors and other subsea structures in floating offshore wind farms: A review

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Water Science and Engineering 2022年第1期15卷 3-14页

作者： B.Mutlu Sumer Veysel Sadan Ozgur Kirca BM SUMER consultancy&Research ITU ARI Teknokent 1Nol5Istanbul 34467Turkey Department of Civil Engineering Istanbul Technical UniversityMaslak 34467Turkey

This article reviews scouring and liquefaction issues for anchor foundations of floating offshore wind *** review is organized in two sections:(1)the scouring issues for drag-embedment anchors(DEAs)and other subsea structures associated with DEAs such as tensioners,clump weights,and chains in floating offshore wind farms;and(2)the liquefaction issues for the same types of structures,particularly for *** scouring processes are described in detail,and the formulae and design guidelines for engineering predictions are included for quantities like scour depth,time scale,and sinking due to general shear failure of the bed soil caused by scoui\The latter is furnished with numerical ***,in the second section,the liquefaction processes are described with special reference to residual liquefaction where pore-water pressure builds up in undrained soils(such as fine sand and silt)under waves,leading to liquefaction of the bed soil and precipitating failure of DEAs and their associated subsea *** integrated mathematical model to deal with liquefaction around and the resulted sinking failure of DEAs,introduced in a recent study,has been *** of the model is illustrated with a numerical *** is believed that the present review and the existing literatures from the"neighboring"fields form a complementary source of information on scour and liquefaction around foundations of floating offshore wind farms.

关键词： Floating structures Liquefaction Offshore structures Offshore wind energy Renewable energy Scouring

High Accuracy When Measuring Physical Constants: From the Perspective of the Information-Theoretic Approach

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Journal of Applied Mathematics and Physics 2020年第5期8卷 861-887页

作者： Boris Menin Refrigeration consultancy Ltd. Beersheba Israel

The practical value of high-precision models of the studied physical phenomena and technological processes is a decisive factor in science and technology. Currently, numerous methods and criteria for optimizing models have been proposed. However, the classification of measurement uncertainties due to the number of variables taken into account and their qualitative choice is still not given sufficient attention. The goal is to develop a new criterion suitable for any groups of experimental data obtained as a result of applying various measurement methods. Using the “information-theoretic method”, we propose two procedures for analyzing experimental results using a quantitative indicator to calculate the relative uncertainty of the measurement model, which, in turn, determines the legitimacy of the declared value of a physical constant. The presented procedure is used to analyze the results of measurements of the Boltzmann constant, Planck constant, Hubble constant and gravitational constant.

关键词： Amount of Information CODATA Boltzmann Constant Gravitational Constant Hubble Constant Planck Constant International System of Units Mathematical Modeling Measurement Relative Uncertainty