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Sedimentation in small-scale irrigation schemes in Ethiopia: Its sources and management

International Journal of Sediment Research 2022年第5期37卷 576-588页

作者： Zerihun Anbesa Gurmu henk ritzema Charlotte de Fraiture Mekonen Ayana Water Resources Management Group Wageningen University Arba Minch University Department of Water Science and Engineering IHE Delft Institute for Water Education Adama Science and Technology University

Numerous irrigation schemes in sub-Saharan Africa(SSA) exhibit excessive sedimentation, resulting in underperformance and high maintenance costs. In the current study, a participatory monitoring program was used to investigate sediment causes and sources, measure the annual sediment load, and monitor desilting campaigns in two small scale irrigation schemes in Ethiopia, Arata-Chufa(100 ha) and Ketar(430 ha), for three years(2016-2018). Sedimentation quantities were huge, where the annual river sediment influx ranged from 220 m3for the Arata-Chufa scheme to 1,741 m3for the Ketar scheme. On average 0.3 m3/m of sediment were removed from the main canal for Arata-Chufa costing 794 days of labor per year. In Ketar, sediment quantities were even greater: 1.1 m3/m was removed requiring 3,118days of labor per year. The sediment influx from the river source amounts to up to 95% for Arata-Chufa and moderately reaches 46% for Ketar, with the remainder of the sediment entering with overland erosion flows. Farmers reported increased sedimentation over time and difficulty paying operation and maintenance fees instead preferring to contribute labor for the desilting campaigns. Sedimentation management is fragile and mainly involves frequent desilting campaigns and unharmonized efforts to reduce overland sediment inflows. Factors contributing to sediment deposition include mild longitudinal bed slopes, the location of the intake, canal layout, and lack of canal banks for protection against surface water inflow in addition to sub-optimal canal operations. Excessive sedimentation is a major challenge resulting in underperformance of numerous irrigation schemes in SSA, and the stakeholders’ lack of awareness of the sources of sedimentation is an underlying factor aggravating sedimentation problems. It is concluded that investigating the sources, extent, and types of sedimentation entering a small-scale irrigation scheme is the basis for reducing maintenance costs and for effective man

关键词： Sediment sources Sediment management Irrigation performance Soil loss River sediment Erosion

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Nanoscale displacement of the image of an atomic source of radiation

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Chinese Optics Letters 2009年第2期7卷 149-151页

作者： henk F. Arnoldus Department of Physics and Astronomy Mississippi State University

Light emitted by an atomic source of radiation appears to travel along a straight line （ray） from the location of the source to the observer in the far field. However, when the energy flow pattern of the radiation is resolved with an accuracy better than an optical wavelength, it turns out that the field lines are usually curved. We consider electric dipole radiation, a prime example of which is the radiation emitted by an atom during an electronic transition, and we show that the field lines of energy flow are in general curves. Near the location of the dipole, the field lines exhibit a vortex structure, and in the far field they approach a straight line. The spatial extension of the vortex in the optical near field is of nanoscale dimension. Due to the rotation of the field lines near the source, the asymptotic limit of a field line is not exactly in the radially outward direction and as a consequence, the image in the far field is slightly shifted. This sub-wavelength displacement of the image of the source should be amenable to experimental observation with contemporary nanoscale-precision techniques.

关键词： Atoms Electric dipole moments Flow patterns Nanotechnology Vortex flow

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Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation

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Chinese Journal of Oceanology and Limnology 2013年第6期31卷 1356-1362页

作者：祖子清穆穆 henk A.DIJKSTRA LASG Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Ocean Circulation and Wave Institute of OceanologyChinese Academy of Sciences Institute for Marine and Atmospheric Research Utrecht Department of Physics and AstronomyUtrecht University

Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation(THC) is investigated with a three-dimensional ocean circulation model,using the conditional nonlinear optimal perturbation *** results show two types of optimal initial perturbations of sea surface salinity,one associated with freshwater and the other with *** types of perturbations excite decadal variability of the *** the same amplitude of initial perturbation,the decadal variation induced by the freshwater perturbation is much stronger than that by the salinity perturbation,suggesting that the THC is more sensitive to freshwater than salinity *** the amplitude of initial perturbation increases,the decadal variations become stronger for both *** salinity perturbations,recovery time of the THC to return to steady state gradually saturates with increasing amplitude,whereas this recovery time increases remarkably for freshwater perturbations.A nonlinear(advective) feedback between density and velocity anomalies is proposed to explain these characteristics of decadal variability *** results are consistent with previous ones from simple box models,and highlight the importance of nonlinear feedback in decadal THC variability.

关键词： thermohaline circulation decadal variability conditional nonlinear optimal perturbation nonlinear advective feedback

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Application of the Conditional Nonlinear Optimal Perturbation Method to the Predictability Study of the Kuroshio Large Meander

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Advances in Atmospheric Sciences 2012年第1期29卷 118-134页

作者： WANG Qiang MU Mu henk A.DIJKSTRA State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atomspheric PhysicsChinese Academy of SciencesBeijing 100029 Graduate University of the Chinese Academy of Sciences Beijing 100049 Key Laboratory of Ocean Circulation and Wave Institute of OceanologyChinese Academy of SciencesQingdao 266071 Institute for Marine and Atmospheric Research Utrecht Department of Physics and AstronomyUtrecht University3584 CC Utrechtthe Netherlands

A reduced-gravity barotropic shallow-water model was used to simulate the Kuroshio path variations. The results show that the model was able to capture the essential features of these path variations. We used one simulation of the model as the reference state and investigated the effects of errors in model parameters on the prediction of the transition to the Kuroshio large meander （KLM） state using the conditional nonlinear optimal parameter perturbation （CNOP-P） method. Because of their relatively large uncertainties, three model parameters were considered： the interracial friction coefficient, the wind-stress amplitude, and the lateral friction coefficient. We determined the CNOP-Ps optimized for each of these three parameters independently, and we optimized all three parameters simultaneously using the Spectral Projected Gradient 2 （SPG2） algorithm. Similarly, the impacts caused by errors in initial conditions were examined using the conditional nonlinear optimal initial perturbation （CNOP-I） method. Both the CNOP-I and CNOP-Ps can result in significant prediction errors of the KLM over a lead time of 240 days. But the prediction error caused by CNOP-I is greater than that caused by CNOP-P. The results of this study indicate not only that initial condition errors have greater effects on the prediction of the KLM than errors in model parameters but also that the latter cannot be ignored. Hence, to enhance the forecast skill of the KLM in this model, the initial conditions should first be improved, the model parameters should use the best possible estimates.

关键词： conditional nonlinear optimal perturbation Kuroshio large meander predictability model parameters

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PLATFORM SELECTION FOR COMPLEX SYSTEMS:BUILDING AUTOMATION SYSTEMS

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Journal of Systems Science and Systems Engineering 2014年第4期23卷 415-438页

作者： Geerten van de Kaa henk Jan de Vries Jafar Rezaei Faculty of Technology Policyand ManagementDelft University of TechnologyJaffalaan 52628BX DelftThe Netherlands Rotterdam School of Management Erasmus UniversityBurgemeester Oudlaan 503062PARotterdam The Netherlands Faculty of TechnologyPolicyand ManagementDelft University of Technology Jaffalaan 52628BX DelftThe Netherlands Faculty of Technology Policyand ManagementDelft University of Technology Jaffalaan 52628BXDelftThe Netherlands

Automation systems for buildings interconnect components and technologies from the information technology industry and the telecommunications *** these industries,existing platforms and new platforms（that are designed to make building automation systems work） compete for market acceptance and consequently several platform battles among suppliers for building automation networking are being *** is unclear what the outcome of these battles will be and also which factors are important in achieving platform *** the fuzziness of decision makers＇ judgments into account,a fuzzy multi-criteria decision-making methodology called the Fuzzy Analytic Hierarchy Process is applied to investigate the importance of such factors in platform battles for building automation *** present the relative importance of the factors for three types of platforms（subsystem platforms,system platforms,and evolved subsystem platforms）.The results provide a first indication that the set of important factors differs per type of *** example,when focusing on other stakeholders,for subsystem platforms,the previous installed base is of importance;for system platforms,the diversity of the network of stakeholders is essential;and for evolved subsystem platforms,the judiciary is an important factor.

关键词： Building automation system complex system platform Fuzzy Analytic Hierarchy Process(AHP) multi-criteria decision-making(MCDM)

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Heritage attributes of post-war housing in Amsterdam

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Frontiers of Architectural Research 2020年第1期9卷 1-19页

作者： Lisanne Havinga Bernard Colenbrander henk Schellen Department of the Built Environment Eindhoven University of TechnologyEindhoventhe Netherlands

Modern heritage,particularly post-war social housing estates,is struggling with negative ***,this research aims to contribute to a better understanding of the heritage significance of post-war housing estates in general and the Western Garden Cities-a post-war neighborhood in Amsterdam-in particular.A review of the limited body of literature on the heritage significance of modern and post-war housing estates was performed.A significance assessment was conducted on a sample of representative case studies by using expert interviews for data *** experts assigned significance levels to attributes based on whether or not they need to be preserved during a sustainable *** highest-valued attributes are parcellation,balconies,and semi-public green *** most negative value was assigned to the application of external insulation,replacement of the window frames by PVC-U,and closed character of the fa(c)ades on the ground floor *** lack of heritage recognition at the lower scale level may either be due to the important details already being lost or details not yet consistently being recognized as the architecture and buildings are understudied in comparison with the urban qualities of post-war heritage.

关键词： Heritage Significance Attributes Management of change Sustainable refurbishment Heritage impact

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Authentication Codes from-ASU Hash Functions with Partially Secret Keys

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Chinese Journal of Electronics 2014年第4期23卷 790-793页

作者： LIU Shengli TILBORG henk van WENG Jian CHEN Kefei Deptartment of Computer Science and Engineering Shanghai Jiao Tong University Deptartment of Mathematics and Computer Science Eindhoven University of Technology Department of Computer Science Jinan University School of Science Hangzhou Normal University

An authentication code can be constructed with a family of-Almost strong universal(-ASU) hash functions, with the index of hash functions as the authentication key. This paper considers the performance of authentication codes from-ASU, when the authentication key is only partially secret. We show how to apply the result to privacy amplification against active attacks in the scenario of two independent partially secret strings shared between a sender and a receiver.

关键词： Information theory Authentication code Privacy amplification Unconditional security

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Induction of desiccation tolerance in desiccation sensitive Citrus limon seeds

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Journal of Integrative Plant Biology 2019年第5期61卷 624-638页

作者： Alexandre Marques Harm Nijveen Charles Somi Wilco Ligterink henk Hilhorst Laboratory of Plant Physiology Wageningen University and ResearchWageningenThe Netherlands Bioinformatics Group Wageningen University and ResearchWageningenThe Netherlands

Many economically important perennial species bear recalcitrant seeds, including tea, coffee, cocoa, mango,citrus, rubber, oil palm and coconut. Orthodox seeds can be dried almost completely without losing viability, but so-called recalcitrant seeds have a very limited storage life and die upon drying below a higher critical moisture content than orthodox seeds. As a result, the development of longterm storage methods for recalcitrant seeds is *** this critical moisture content would be very valuable since dry seed storage is the safest, most convenient and cheapest method for conserving plant genetic ***, we have attempted to induce desiccation tolerance(DT) in the desiccation sensitive seeds of Citrus limon. We show that DT can be induced by paclobutrazol(an inhibitor of gibberellin biosynthesis) and we studied its associated transcriptome to delineate the molecular mechanisms underlying this induction of DT. Paclobutrazol not only interfered with gibberellin related gene expression but also caused extensive changes in expression of genes involved in the biosynthesis and signaling of other hormones. Paclobutrazol induced a transcriptomic switch encompassing suppression of biotic-and induction of abiotic *** hypothesize that this is the main driver of the induction of DT by paclobutrazol in C. limon seeds.

关键词： economically important recalcitrant seeds paclobutrazol in C.limon seeds

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Simplified thermal and hygric building models： A literature review

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Frontiers of Architectural Research 2012年第4期1卷 318-325页

作者： Rick Kramer Jos van Schijndel henk Schellen Deportment of the Built Environment Eindhoven University of Technology Eindhoven 5612 AZ The Netherlonds

This paper provides a systematic literature review on simplified building modelso Questions are answered like： What kind of modelling approaches are applied？ What are their （dis）advantages？ What are important modelling aspects？ The review showed that simplified building models can be classified into neural network models （black box）, linear parametric models （black box or grey box） and lumped capacitance models （white box）. Research has mainly dealt with network topology, but more research is needed on the influence of input parameters. The review showed that particularly the modelling of the influence of sun irradiation and thermal capacitance is not performed consistently amongst researchers. Furthermore, a model with physical meaning, dealing with both temperature and relative humidity, is still lacking. Inverse modelling has been widely applied to determine models parameters. Different optimization algorithms have been used, but mainly the conventional Gaus-Newton and the newer genetic algorithms. However, the combination of algorithms to combine their strengths has not been researched. Despite all the attention for state of the art building performance simulation tools, simplified building models should not be forgotten since they have many useful applications. Further research is needed to develop a simplified hygric and thermal building model with physical meaning.

关键词： Literature review Building performancesimulation Simplified buildingmodels Inverse modelling Climate change

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Connected autonomous vehicles for improving mixed traffic efficiency in unsignalized intersections with deep reinforcement learning

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Communications in Transportation Research 2021年第1期1卷 139-143页

作者： Bile Peng Musa Furkan Keskin Balazs Kulcsar henk Wymeersch Institute for Communications Technology TU Braunschweig38106BraunschweigGermany Department of Electrical Engineering Chalmers University of Technology41296GothenburgSweden

Human driven vehicles(HDVs)with selfish objectives cause low traffic efficiency in an un-signalized *** the other hand,autonomous vehicles can overcome this inefficiency through perfect *** this paper,we propose an intermediate solution,where we use vehicular communication and a small number of autonomous vehicles to improve the transportation system efficiency in such *** our solution,two connected autonomous vehicles(CAVs)lead multiple HDVs in a double-lane intersection in order to avoid congestion in front of the *** CAVs are able to communicate and coordinate their behavior,which is controlled by a deep reinforcement learning(DRL)*** design an altruistic reward function which enables CAVs to adjust their velocities flexibly in order to avoid queuing in front of the *** proximal policy optimization(PPO)algorithm is applied to train the policy and the generalized advantage estimation(GAE)is used to estimate state *** results show that two CAVs are able to achieve significantly better traffic efficiency compared to similar scenarios without and with one altruistic autonomous vehicle.

关键词： Connected vehicles Autonomous driving Intelligent transportation systems Deep reinforcement learning

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