Relevant bibliographies by topics / Multi-Level Fast Multipole

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers
  5. Reports

Academic literature on the topic 'Multi-Level Fast Multipole'

Author: Grafiati
Published: 6 September 2023

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Journal articles on the topic "Multi-Level Fast Multipole"

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Amini, S., and A. T. J. Profit. "Multi-level fast multipole solution of the scattering problem." Engineering Analysis with Boundary Elements 27, no. 5 (May 2003): 547–64. http://dx.doi.org/10.1016/s0955-7997(02)00161-3.

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Lee, Hyunsoo, Jae-Won Rim, Il-Suek Koh, and Seung-Mo Seo. "Computational Complexity of BiCGstab(l) in Multi-Level Fast Multipole Method(MLFMM) and Efficient Choice of l." Journal of Korean Institute of Electromagnetic Engineering and Science 29, no. 3 (March 2018): 167–70. http://dx.doi.org/10.5515/kjkiees.2018.29.3.167.

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Pan, X. M., and X. Q. Sheng. "A Highly Efficient Parallel Approach of Multi-level Fast Multipole Algorithm." Journal of Electromagnetic Waves and Applications 20, no. 8 (January 2006): 1081–92. http://dx.doi.org/10.1163/156939306776930321.

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Yun, Dal-jae, Haewon Jung, Hoon Kang, Woo-Yong Yang, and Dong-Wook Seo. "Acceleration of the Multi-Level Fast Multipole Algorithm Using K-Means Clustering." Electronics 9, no. 11 (November 16, 2020): 1926. http://dx.doi.org/10.3390/electronics9111926.

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The multilevel fast multipole algorithm (MLFMA) using K-means clustering to accelerate electromagnetic scattering analysis for large complex targets is presented. By replacing the regular cube grouping with the K-means clustering, the addition theorem is more accurately approximated. The convergence rate of an iterative solver is thus improved significantly. However, irregular centroid locations as a result of the K-means clustering increase the amount of explicit transfer function calculations, compared with the regular cubes. In the MLFMA, a multilevel hierarchical structure is applied to the finite multipole method (FMM) to reduce transfer function calculations. Therefore, the MLFMA is suitable for applying K-means clustering. Simulation results with both canonical and realistic targets show an improvement in the computation time of the proposed algorithm.
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Nam, Jeong-Hun, Jeong-Un You, and Il-Suek Koh. "Large Complex Impedance and Dielectric Inhomogeneous Structure Scattering Analysis Based on Multi-Level Fast Multipole Method and Iterative Physical Optics." Journal of Korean Institute of Electromagnetic Engineering and Science 32, no. 10 (October 2021): 916–24. http://dx.doi.org/10.5515/kjkiees.2021.32.10.916.

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Burgschweiger, Ralf, Martin Ochmann, Ingo Schäfer, and Bodo Nolte. "Optimization and limitations of a preconditioned multi-level fast multipole algorithm for acoustical calculations." Journal of the Acoustical Society of America 131, no. 4 (April 2012): 3512. http://dx.doi.org/10.1121/1.4709276.

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Chaillat, Stéphanie, Marc Bonnet, and Jean-François Semblat. "A multi-level fast multipole BEM for 3-D elastodynamics in the frequency domain." Computer Methods in Applied Mechanics and Engineering 197, no. 49-50 (September 2008): 4233–49. http://dx.doi.org/10.1016/j.cma.2008.04.024.

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Grasso, Eva, Stéphanie Chaillat, Marc Bonnet, and Jean-François Semblat. "Application of the multi-level time-harmonic fast multipole BEM to 3-D visco-elastodynamics." Engineering Analysis with Boundary Elements 36, no. 5 (May 2012): 744–58. http://dx.doi.org/10.1016/j.enganabound.2011.11.015.

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Fu, Liwei, Max Daiber-Huppert, Karsten Frenner, and Wolfgang Osten. "Simulation of realistic speckle fields by using surface integral equation and multi-level fast multipole method." Optics and Lasers in Engineering 162 (March 2023): 107438. http://dx.doi.org/10.1016/j.optlaseng.2022.107438.

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Yoo, Jeong-Un, and Il-Suek Koh. "Comparison of Linear Iteration Schemes to Improve the Convergence of Iterative Physical Optics for an Impedance Scatterer." Journal of Electromagnetic Engineering and Science 23, no. 1 (January 31, 2023): 78–80. http://dx.doi.org/10.26866/jees.2023.1.l.12.

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The conventional iterative physical optics (IPO) method updates the surface current based on the Jacobi iteration scheme, which typically diverges for large objects. To control the convergence property of the IPO method, other iteration schemes, such as Gauss–Seidel and successive over-relaxation, can be used. In this study, we compare the convergence properties of three iteration schemes for scatterings by five scatterers comprising electrically perfect or imperfect conductors modeled with an impedance material. The accuracy of the IPO method is compared with that of the multi-level fast multipole method.
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Dissertations / Theses on the topic "Multi-Level Fast Multipole"

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Rawat, Vineet. "High-order solution of radio propagation problems using the multi-level fast multipole algorithm." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81562.

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Wireless network planning requires accurate, site-specific urban and indoor radio propagation models. Traditionally, such models have been developed using approximate asymptotic methods. This thesis examines rigorous solution methods for radio propagation in electrically large environments.
The high-order locally corrected Nystrom (LCN) method is applied to the combined field integral equation (CFIE) for scattering from perfect electrical conductors (PEC) in two dimensions. The direct solution of the resulting linear system of equations requires O(N2) time per iteration of an iterative solver. Application of the multi-level fast multipole algorithm (MLFMA) reduces iteration time to O(Nlog N). The MLFMA employs an approximation however, and the error introduced must be controlled via the selection of appropriate parameters.
An implementation of the LCN method and MLFMA is tested using various electrically large scattering bodies. The solution of a simple urban radio propagation problem is then examined and the feasibility of its rigorous solution is demonstrated.
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Barakat, Khalil. "The multi-level fast multipole method and prediction of cellular signal strength in an urban environment /." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33955.

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There is great interest in solving microwave propagation problems in the urban environment, for planning and simulating cell phone systems. The most accurate approach would be to solve Maxwell's equations for the unknown field strength at every point. Traditional computational methods require dividing space into N subregions (e.g. finite elements) that are no longer than about half a wavelength across, and introducing several unknowns per subregion. This thesis investigates computationally efficient methods of solving such problems on electrically large domains and as a result, the Multi-Level Fast Multi-pole Method (MLFMM) is implemented to resolve two-dimensional problems and predict cellular signal strength. The simulation tool computational cost is of O(N ln N) per iteration, as compared to O(N2) for more straightforward methods. The tool was successfully tested in the case of cylindrical scatterers for whom analytical solutions are available for comparison. It was then used to predict the field strength in a simple urban model.
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Wei, Jiangong. "Surface Integral Equation Methods for Multi-Scale and Wideband Problems." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408653442.

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Cwikla, Martin. "The Low-Frequency Multi-Level Fast Multipole Method on Graphics Processors." 2009. http://hdl.handle.net/1993/3209.

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The Fast Multipole Method (FMM) allows for rapid evaluation of the fundamental solution of the Helmholtz equation, known as Green's function. Evaluation times are reduced from O(N^2), using the direct approach, down to O(N log N), with an accuracy specified by the user. The Helmholtz equation, and variations thereof, including the Laplace and wave equations, are used to describe physical phenomena in electromagnetics, acoustics, heat dissipation, and many other applications. This thesis studies the acceleration of the low-frequency FMM, where the product of the wave number and the translation distance of expansion coefficients is relatively low. A general-purpose graphics processing unit (GPGPU), with native support of double-precision arithmetic, was used in the implementation of the LF FMM, with a resulting speedup of 4-22X over a conventional central processing unit (CPU), running in a single-threaded manner, for various simulations involving hundreds of thousands to millions of sources.
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Muniganti, Harikiran. "Inverse Problems in 3D Full-wave Electromagnetics." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5807.

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An inverse problem in Electromagnetics (EM) refers to the process of reconstructing the physical system by processing the measured data of its electromagnetic properties. Inverse problems are typically ill-posed, and this makes them far more challenging than the typically well-posed forward problem. The solution of such inverse problems finds applications in nondestructive testing and evaluation, biomedical imaging, geophysical exploration etc. This thesis addresses some inverse problems specific to the area of electromagnetics, arising in three different scenarios. The first problem is 3-D quantitative imaging primarily targeted towards bio-medical applications. The task is to retrieve the dielectric properties, location and the shape of an unknown object from the measured scattered field. The unknown object is modeled by discretization into several voxels, with each voxel having its own dielectric property. As the inverse problem is non-linear, typically an iterative optimization process is adopted, and a forward problem needs to be solved at every iteration. The total time for reconstruction depends on the forward solver time and the number of iterations. In many cases, the number of unknowns to be reconstructed is prohibitively large. Further, the non-convergence or false-convergence of the optimization process presents its own challenge. This thesis proposes two methodologies to solve these challenges. In the first approach a multilevel methodology is proposed where voxels are hierarchically decomposed into smaller voxels based on an appropriate indicator, leading to a non-uniform multilevel voxel structure aimed at reducing the eventual number of unknowns to be solved for, also enabling faster convergence. In the second approach, a two-stage framework is proposed comprising of Machine Learning classification followed by optimization (ML-OPT). The first stage generates an appropriate adaptive grid for the optimization process and provides a suitable initial guess aiding convergence to the global minima. This approach is aimed at detecting breast tumors where the optimization algorithm can aim for higher resolution in the suspected tumor region, while using lower resolution elsewhere. The second problem is in the domain of high-speed circuits and is focused on synthesis of transmission line physical parameters given the desired electrical parameters like characteristic impedance and propagation constant. A forward solver is used to train Neural network for several different configurations for analysis and an optimization algorithm is used for synthesis. The third problem is focused on finding the source of radiation in an electronic system e.g. an automotive ECU, given the measured field at the antenna in the radiated emissions setup. The source of radiation can be from common mode current on the cable harness or from the Design Under Test (DUT). A method based on Huygens box is proposed to quantify the radiation from cable and DUT at each frequency. On each cell of the Huygens box the value of electric field computed at the observation point taking the Electric Current (J) and Magnetic Current (M) on that cell as sources and this information on the Huygens box is used to quantify the radiation. Some part of the presented work is used via technology-transfer at Simyog Technology Pvt. Ltd., an IISc incubated startup, to develop a simulation software called Compliance-scope which allows the hardware designer to predict the EMI/EMC performance of electronics modules from an early design stage.
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Book chapters on the topic "Multi-Level Fast Multipole"

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Bonnet, Marc, Stéphanie Chaillat, and Jean-François Semblat. "Multi-Level Fast Multipole BEM for 3-D Elastodynamics." In Recent Advances in Boundary Element Methods, 15–27. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-1-4020-9710-2_2.

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Zeblah, Abdelkader, Abdelkader Rami, and Eric Châtelet. "A Comparison for Optimal Allocation of a Reliability Algorithms Production System." In Handbook of Research on Artificial Intelligence Techniques and Algorithms, 564–93. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-7258-1.ch018.

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The most important phase in many industrial power applications is the design problem. Usually the demand increases randomly with time in the form of a cumulative demand curve. To adapt the power system capacity to the demand, new power architecture is predicted. To build this latter, the reliability optimization plays an important role to find the realizable power system architecture. This chapter describes and uses different meta-heuristics optimization methods to solve the redundancy optimization problem for multi-state series-parallel power systems. The authors consider the case where redundant power components are chosen to achieve a desirable level of reliability. The power components of the system are characterized by their cost, capacity, and reliability. The proposed meta-heuristics seek the optimal architectures of series-parallel power systems in which a multiple choice of components are allowed from a list of products available in the market. The approach has the advantage of allowing power components with different parameters to be allocated in power systems. To allow fast reliability estimation, a Moment Generating Function (MGF) method is applied. An illustrative example is presented.
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Huh, Soon-Young, Kae-Hyun Moon, and Jin-Kyun Ahn. "Cooperative Query Processing via Knowledge Abstraction and Query Relaxation." In Advanced Topics in Database Research, Volume 1, 211–28. IGI Global, 2002. http://dx.doi.org/10.4018/978-1-930708-41-9.ch011.

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As database users adopt a query language to obtain information from a database, a more intelligent query answering system is increasingly needed that cooperates with the users to provide informative responses by understanding the intent behind a query. The effectiveness of decision support would improve significantly if the query answering system returned approximate answers rather than a null information response when there is no matching data available. Even when exact answers are found, neighboring information is still useful to users if the query is intended to explore some hypothetical information or abstract general fact. This chapter proposes an abstraction hierarchy as a framework to practically derive such approximate answers from ordinary everyday databases. It provides a knowledge abstraction database to facilitate the approximate query answering. The knowledge abstraction database specifically adopts an abstraction approach to extract semantic data relationships from the underlying database, and uses a multi-level hierarchy for coupling multiple levels of abstraction knowledge and data values. In cooperation with the underlying database, the knowledge abstraction database allows the relaxation of query conditions so that the original query scope can be broadened and thus information approximate to exact answers can be obtained. Conceptually abstract queries can also be posed to provide a less rigid query interface. A prototype system has been implemented at KAIST and is being tested with a personnel database system to demonstrate the usefulness and practicality of the knowledge abstraction database in ordinary database systems.
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Conference papers on the topic "Multi-Level Fast Multipole"

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Lord, J. A. "Multi-level fast multipole for antenna modelling." In Twelfth International Conference on Antennas and Propagation (ICAP 2003). IEE, 2003. http://dx.doi.org/10.1049/cp:20030075.

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Borries, Oscar, Per Christian Hansen, Stig B. Sorensen, Peter Meincke, and Erik Jorgensen. "Gaussian translation operator for Multi-Level Fast Multipole Method." In 2014 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting. IEEE, 2014. http://dx.doi.org/10.1109/aps.2014.6905403.

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Azhar, Arslan, and Thomas F. Eibert. "Numerical Synthesis of Translation Operators for the Multi-Level Fast Multipole Method." In 2020 14th European Conference on Antennas and Propagation (EuCAP). IEEE, 2020. http://dx.doi.org/10.23919/eucap48036.2020.9135193.

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Huapeng Zhao, Jun Hu, and Zaiping Nie. "A simplified near-field preconditioner based on multi-level fast multipole algorithm." In 2007 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference. IEEE, 2007. http://dx.doi.org/10.1109/imoc.2007.4404407.

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Li, Tianmeng, Jinbo Liu, and Zengrui Li. "An effective sparse approximate inverse preconditioner for the multi-level fast multipole algorithm." In 2018 IEEE MTT-S International Wireless Symposium (IWS). IEEE, 2018. http://dx.doi.org/10.1109/ieee-iws.2018.8400903.

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Zhao, Huapeng, Siping Gao, Weijiang Zhao, Qun Wan, Jun Hu, and Zhizhang Chen. "Estimation of interfrence between antennas on large platforms using physics-based truncation model and multi-level fast multipole method." In 2016 IEEE International Symposium on Electromagnetic Compatibility - EMC 2016. IEEE, 2016. http://dx.doi.org/10.1109/isemc.2016.7571743.

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Chung, Shen Shou Max, and Shih-Chung Tuan. "Comparison of NASA Almond Radar Cross Section Simulation Results from Shoot-Bouncing-Ray Method and Multi-Level-Fast-Multipole-Method." In 2020 International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM). IEEE, 2020. http://dx.doi.org/10.1109/iwem49354.2020.9237433.

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Wei, Jian-gong, Zhen Peng, and Jin-Fa Lee. "A hierarchical multi-level fast multipole method for wideband multiscale electromagnetic wave scattering from non-penetrable targets in R3." In 2012 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting. IEEE, 2012. http://dx.doi.org/10.1109/aps.2012.6348561.

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Wang, Haitao, and Xin Wang. "Study on Temperature Distribution of Pebble-Bed HTR Fuel Element by Using Boundary Element Method." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97454.

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Spherical fuel elements with a diameter of 60mm are basic units of the nuclear fuel for the pebble-bed high temperature gas-cooled reactor (HTR). Each fuel element is treated as a graphite matrix containing around 10,000 randomly distributed fuel particles. The essential safety concept of the pebble-bed HTR is based on the objective that maximum temperature of the fuel particles does not exceed the design value. In this paper, a microstructure-based boundary element model is proposed for the large-scale thermal analysis of a spherical fuel element. This model presents detailed structural information of a large number of coated fuel particles dispersed in a spherical graphite matrix in order that temperature distributions at the level of fuel particles can be evaluated. The model is meshed with boundary elements in conjunction with the fast multipole method (FMM) in order that such large-scale computation is performed only in a personal desktop computer. Taking advantage of the fact that fuel particles are of the same shape, a similar sub-domain approach is used to establish the temperature translation mechanism between various layers of each fuel particle and to simplify the associated boundary element formulation. The numerical results demonstrate large-scale capacity of the proposed method for the multi-level temperature evaluation of the pebble-bed HTR fuel elements.
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Eichardt, Roland, Jens Haueisen, Thomas R. Knosche, and Ernst G. Schukat-Talamazzini. "The Application of Single- and Multi-Level Fast Evolution Strategies for the Reconstruction of Multiple Neuromagnetic Sources." In 2007 Joint Meeting of the 6th International Symposium on Noninvasive Functional Source Imaging of the Brain and Heart and the International Conference on Functional Biomedical Imaging. IEEE, 2007. http://dx.doi.org/10.1109/nfsi-icfbi.2007.4387699.

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Reports on the topic "Multi-Level Fast Multipole"

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Carin, Lawrence. Multi-Level Fast Multipole Algorithm w/ Application to Foliage Penetrating Radar. Fort Belvoir, VA: Defense Technical Information Center, September 2000. http://dx.doi.org/10.21236/ada384420.

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Masumoto, Takayuki. The Effect of Applying the Multi-Level Fast Multipole Algorithm to the Boundary Element Method. Warrendale, PA: SAE International, September 2005. http://dx.doi.org/10.4271/2005-08-0589.

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Baliki, Ghassan, Dorothee Weiffen, Melodie Al Daccache, Aysegül Kayaoglu, Lara Sujud, Hadi Jaafar, Hala Ghattas, and Tilman Brück. Seeds for recovery: The long-term impacts of a complex agricultural intervention on welfare, behaviour and stability in Syria (SEEDS). Centre for Excellence and Development Impact and Learning (CEDIL), April 2023. http://dx.doi.org/10.51744/crpp7.

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There is scarce evidence on whether and how assistance in humanitarian emergencies and conflict settings impacts household well-being and behaviour. Conducting rigorous impact evaluations in such settings poses multiple challenges in design and data collection. In SEEDS, we evaluate the impact of a complex large-scale multi-arm agricultural intervention on productivity, food security, and resilience in the context of an on-going humanitarian crisis in Syria. Specifically, we identify the causal impacts of agricultural asset transfers over various time horizons (the short-, medium-, and long-run), and across different conditions and subgroups (gender and conflict intensity) at the household-level. We evaluate the effectiveness of irrigation rehabilitation separately at the community-level. We use and combine various data sources, including a unique survey panel dataset collected over a period of four years from multiple governorates in Syria, satellite remote-sensing data, and publicly available violent conflict incidence and weather data. Our findings from using cutting-edge machine and deep learning approaches together with innovative balancing and analytical methods can be summarised as follows: For average treatment effects at the household-level, we find that the provision of agricultural asset support leads to significant improvements in food security in the short- and long-term, three years after the intervention. The positive and significant effect on food security is driven mainly by the increased consumption of healthy food items such as vegetables. In the long-run, livestock support reduces the use of harmful coping strategies households employ to deal with food shortages. Interestingly, we find that households who received vegetable kits are not just less likely to sell their productive assets in the long-term but also are less likely to marry off their young daughters or send their children to work. Overall, we find that both agricultural and livestock asset support is key to improving households’ resilience in the long-term. The irrigation rehabilitation interventions at the community-level positively affected agricultural productivity compared to the pre-intervention and pre-conflict periods. However, these effects were only significantly pronounced in the spring season. As for the heterogeneity analysis, we find that female-headed households benefit remarkably more in terms of food security in the medium-term compared to male-headed families. Moreover, households residing in areas that are moderately affected by violent conflict show stronger food security improvements compared to households from peaceful or conflict-intense settings. Overall, we draw three overarching lessons from our findings in SEEDS: First, agricultural support in protracted conflict settings effectively improves the long-term welfare and resilience of vulnerable households. In fact, the presence of an ongoing humanitarian operation acts as a social safety net if circumstances deteriorate suddenly. Second, not all interventions are equally effective, and not all households equally benefit, underscoring the need to design and implement inclusive context-specific interventions with detailed targeting. Third, methodologically, using multiple remote data sources and machine learning methods help overcome challenges in conducting rigorous impact evaluations in hard-to-reach humanitarian emergency settings.
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Salavisa, Isabel, Mark Soares, and Sofia Bizarro. A Critical Assessment of Organic Agriculture in Portugal: A reflection on the agro-food system transition. DINÂMIA'CET-Iscte, 2021. http://dx.doi.org/10.15847/dinamiacet-iul.wp.2021.05.

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Over the last few decades, the organic agriculture sector has experienced sustained growth. Globally, as well as in the European Union and Portugal, organic production accounts for just under 10% of total Utilised Agricultural Area (UAA) (FiBL, 2019; Eurostat, 2019; DGADR, 2019; INE, 2019; GPP, 2019). This growth has been seen in terms of production, number of producers, amount of retail sales, imports and exports. This article attempts to build on the multi-level perspective (MLP) of the socio-technical (ST) transitions theory by employing a whole systems analysis (Geels, 2018) of organic agriculture in Portugal, which defends an integrated vision of the systems, where multiple interactions occur within and among the niche, the regime and the landscape levels. This approach has been employed in order to develop a critical analysis of the current state of the Portuguese organic agriculture sector, stressing the multiplicity of elements that are contributing to the agro-food system´s transformation into a more sustainable one. In fact, the agro-food system is related with climate change but also has connections with other domains such as public health, water management, land use and biodiversity. Therefore, it is affected by shifts in these areas. This analysis considers developments in increasing domestic organic production, number of producers, amount of retail sales, imports, exports, market innovations, and the sector´s reconfiguration. The organic sector´s increase has been attributed to European regulation, institutionalization, standardization, farmer certification, external (government) subsidy support programs, incremental market improvements (visibility and product access), the emergence of new retailers, the rise of supporting consumers and a shift away from conventional agriculture (Truninger, 2010; DGADR, 2019; Pe´er et al, 2019). However, together with positive incentives, this sector also faces numerous barriers that are hindering a faster transformation. Difficulties for the sector to date have included: product placement; a disconnect between production, distribution and marketing systems; high transport costs; competition from imports; European subsidies focused on extensive crops (pastures, olive groves, and arable crops), entailing a substantial growth in the area of pasture to the detriment of other crops; the fact that the products that are in demand (fresh vegetables and fruit) are being neglected by Portuguese producers; expensive certification procedures; lack of adequate support and market expertise for national producers; the hybrid configuration of the sector; and price. Organic agriculture as a niche-innovation is still not greatly contributing to overall agricultural production. The low supply of organic products, despite its ever-increasing demand, suggests that a transition to increased organic production requires a deeper and faster food system reconfiguration, where an array of distinct policies are mobilized and a diversity of actions take place at different levels (Geels, 2018; Pe´er et al, 2019). This paper will attempt to contribute an overall critical assessment of the organic sector´s features and evolution and will identify some of the main obstacles to be overcome, in order to boost the sustainability transition of the agro-food system in Portugal.
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Gur, Amit, Edward Buckler, Joseph Burger, Yaakov Tadmor, and Iftach Klapp. Characterization of genetic variation and yield heterosis in Cucumis melo. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7600047.bard.

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Project objectives: 1) Characterization of variation for yield heterosis in melon using Half-Diallele (HDA) design. 2) Development and implementation of image-based yield phenotyping in melon. 3) Characterization of genetic, epigenetic and transcriptional variation across 25 founder lines and selected hybrids. The epigentic part of this objective was modified during the course of the project: instead of characterization of chromatin structure in a single melon line through genome-wide mapping of nucleosomes using MNase-seq approach, we took advantage of rapid advancements in single-molecule sequencing and shifted the focus to Nanoporelong-read sequencing of all 25 founder lines. This analysis provides invaluable information on genome-wide structural variation across our diversity 4) Integrated analyses and development of prediction models Agricultural heterosis relates to hybrids that outperform their inbred parents for yield. First generation (F1) hybrids are produced in many crop species and it is estimated that heterosis increases yield by 15-30% globally. Melon (Cucumismelo) is an economically important species of The Cucurbitaceae family and is among the most important fleshy fruits for fresh consumption Worldwide. The major goal of this project was to explore the patterns and magnitude of yield heterosis in melon and link it to whole genome sequence variation. A core subset of 25 diverse lines was selected from the Newe-Yaar melon diversity panel for whole-genome re-sequencing (WGS) and test-crosses, to produce structured half-diallele design of 300 F1 hybrids (MelHDA25). Yield variation was measured in replicated yield trials at the whole-plant and at the rootstock levels (through a common-scion grafted experiments), across the F1s and parental lines. As part of this project we also developed an algorithmic pipeline for detection and yield estimation of melons from aerial-images, towards future implementation of such high throughput, cost-effective method for remote yield evaluation in open-field melons. We found extensive, highly heritable root-derived yield variation across the diallele population that was characterized by prominent best-parent heterosis (BPH), where hybrids rootstocks outperformed their parents by 38% and 56 % under optimal irrigation and drought- stress, respectively. Through integration of the genotypic data (~4,000,000 SNPs) and yield analyses we show that root-derived hybrids yield is independent of parental genetic distance. However, we mapped novel root-derived yield QTLs through genome-wide association (GWA) analysis and a multi-QTLs model explained more than 45% of the hybrids yield variation, providing a potential route for marker-assisted hybrid rootstock breeding. Four selected hybrid rootstocks are further studied under multiple scion varieties and their validated positive effect on yield performance is now leading to ongoing evaluation of their commercial potential. On the genomic level, this project resulted in 3 layers of data: 1) whole-genome short-read Illumina sequencing (30X) of the 25 founder lines provided us with 25 genome alignments and high-density melon HapMap that is already shown to be an effective resource for QTL annotation and candidate gene analysis in melon. 2) fast advancements in long-read single-molecule sequencing allowed us to shift focus towards this technology and generate ~50X Nanoporesequencing of the 25 founders which in combination with the short-read data now enable de novo assembly of the 25 genomes that will soon lead to construction of the first melon pan-genome. 3) Transcriptomic (3' RNA-Seq) analysis of several selected hybrids and their parents provide preliminary information on differentially expressed genes that can be further used to explain the root-derived yield variation. Taken together, this project expanded our view on yield heterosis in melon with novel specific insights on root-derived yield heterosis. To our knowledge, thus far this is the largest systematic genetic analysis of rootstock effects on yield heterosis in cucurbits or any other crop plant, and our results are now translated into potential breeding applications. The genomic resources that were developed as part of this project are putting melon in the forefront of genomic research and will continue to be useful tool for the cucurbits community in years to come.
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