Готові списки джерел за темами / DDA simulation

Добірка наукової літератури з теми "DDA simulation"

Автор: Grafiati

Опубліковано: 7 липня 2024

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Статті в журналах з теми "DDA simulation":

Ma, Guichen, Hiroyuki Matsuyama, Satoshi Nishiyama, and Yuzo Ohnishi. "Practical studies on rockfall simulation by DDA." Journal of Rock Mechanics and Geotechnical Engineering 3, no. 1 (March 2011): 57–63. http://dx.doi.org/10.3724/sp.j.1235.2011.00057.

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Chen, Guangqi, Manchao He, and Fusong Fan. "Rock Burst Analysis Using DDA Numerical Simulation." International Journal of Geomechanics 18, no. 3 (March 2018): 04018001. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001055.

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Fu, Xiaodong, Jingyu Kang, Qian Sheng, Lu Zheng, Wenjie Du, and Haifeng Ding. "Investigation of 2D Seismic DDA Method for Numerical Simulation of Shaking Table Test of Rock Mass Engineering." Mathematics 10, no. 8 (April 17, 2022): 1330. http://dx.doi.org/10.3390/math10081330.

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Since the basic theory of the discontinue deformation analysis (DDA) method was proposed, the DDA open source has gone through a long development process. At present, different kinds of programs have been widely applied in rock mass engineering such as slope, dam, and tunnel. This paper introduces the solution principle of DDA motion equations in detail, as well as the development status of the 2D open-source program. Numerical simulation of shaking table test of rock mass engineering using 2D DDA program is highlighted, and investigations of seismic wave pre-processing and seismic input method are carried out. First, based on the Newmark integration scheme, the integration algorithms of synthetic or measured seismic wave time history, correction function of seismic wave, and DDA simulation are unified. Then, three seismic input methods are implanted in the DDA program, and the applicability of various seismic input methods is discussed. On this basis, using the improved seismic 2D DDA program, a shaking table test of typical rock mass engineering is simulated. Through the comparison between the theoretical/test data and simulation results, the reliability of the improved DDA program in seismic response analysis is verified; the large mass method and the large stiffness method are more suitable for rigid foundation, such as shaking table test; the propagation of the seismic wave presents a significant amplification effect due to the reflection, refraction, and diffraction in the tunnel. The research results provide DDA theory and an open-source program for analyzing the seismic response of rock mass engineering.

Gao, Ya Nan, Feng Gao, M. R. Yeung, and Qing Hui Jiang. "Numerical Simulation of Coal Mining Excavation Based on Discontinuous Deformation Analysis." Applied Mechanics and Materials 138-139 (November 2011): 187–92. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.187.

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The movement and deformation of rock stratum occur when the excavation is carries out during the underground mining process. Rock is a continuous-discontinuous material so the continuum mechanics method may not handle the rock problem well. The discontinuous deformation analysis (DDA) method which discretizes the rock mass to block system can describe the large displacement and deformation of rock blocks, especially the rock stratum collapse. The DDA was employed in this paper to analysis a mining excavation process. The displacement field and stress field of rock stratum was computed. The result shows that the DDA can handle the mining excavation and the rock stratum movement and deformation problem well.

Octavia, Karina, Jian-Hong Wu, and Luky Handoko. "Investigating the Stability of the Candi Kelir using DDA." IOP Conference Series: Earth and Environmental Science 1249, no. 1 (October 1, 2023): 012016. http://dx.doi.org/10.1088/1755-1315/1249/1/012016.

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Abstract Candi Kelir, which is a candi in Prambanan, is a historical masonry structures threatened by high potency of earthquake in Indonesia. Investigating the stability of Candi Prambanan is essential for determining the capability to withstand earthquake loads. Discontinuous Deformation Analysis (DDA) has been extensively applied in the disciplines of rock mechanics and rock engineering. Two-dimensional DDA is chosen to simulate the behaviour of Candi Kelir towards earthquake load. Geometry of each block of Candi Kelir is obtained by Close Range Photogrammetry (CRP) method. Simulation of Candi Kelir is conducted using the seismic excitation from the destructive 2006 Yogyakarta Earthquake. The result of the simulation shows the capability of DDA to simulate the behaviour of masonry structure which allows fully detachment of the blocks. During the earthquake, most of the top structures are failing, thus DDA can simulate and generate the result. Wider application of DDA into the historical masonry structure will be helpful to prevent more damage due to earthquakes.

Wang, Xiao-Bo, Wen-Jie Xu, Bing-Yin Zhang, and Qi-Cheng Sun. "Particle crushing simulations with improved discontinuous deformation analysis." Engineering Computations 31, no. 7 (September 30, 2014): 1321–41. http://dx.doi.org/10.1108/ec-02-2013-0051.

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Purpose – Rock-fill dams are embankments of compacted free-draining granular earth containing an impervious zone. Earth utilized in such dams often contains a high percentage of large particles – hence the term rock-fill. Mass stability of these dams results from friction and particle interactions rather than through a cementing agent binding the particles together. However, high-stress conditions and prolonged exposure to the elements can severely damage rock-fill. Therefore, understanding and modeling rock-fill breakage is important for dam engineering. The purpose of this paper is to improve discontinuous deformation analysis (DDA) techniques for modeling rock-fill breakage, proving the new method using simulations of spherical particle crushing. Design/methodology/approach – This work models rock-fill as bonded ellipsoid particles, and develops an improved DDA method to model the breakage of particle assemblies. The paper starts by describing the principles of three-dimensional DDA for spherical particles, and then derives the submatrices for normal contact, shear contact, and frictional force. The new algorithm incorporates a bond model with a revised open-close iteration algorithm into the DDA method to simulate particle crushing. To validate the improved DDA method, calculated particle contacts and movements are validated against theoretical results. Finally, this work performs a series of point-loading experimental tests for cement ellipsoid particles of both high and low compression strengths, with the test results compared against the results from corresponding DDA simulations. Findings – In particle crushing tests, the force and displacement show an approximately linear relationship until the crushing point, at which point low compression ellipsoid particles split into several large pieces while the high-compression particles break into many small fragments. The DDA simulation results are in good agreement with the crushing tests, demonstrating the validity of the DDA method for solving particle crushing problems. Although the improved DDA model is applicable to rock-fill particle crushing studies, some issues remain, particularly in increasing calculation efficiency and performing large-scale computations and long real-time simulations. Future research should address these issues. Originality/value – A bond model with a revised open-close iteration algorithm is incorporated into the DDA method. The simulated results shed insight into rock-fill crushing mechanisms, an element of concern in engineering practices.

Zhang, Guoxin, Zhengqi Lei, and Heng Cheng. "Shear Creep Simulation of Structural Plane of Rock Mass Based on Discontinuous Deformation Analysis." Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/1582825.

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Numerical simulations of the creep characteristics of the structural plane of rock mass are very useful. However, most existing simulation methods are based on continuum mechanics and hence are unsuitable in the case of large displacements and deformations. The discontinuous deformation analysis method proposed by Genhua is a discrete one and has a significant advantage when simulating the contacting problem of blocks. In this study, we combined the viscoelastic rheological model of Burgers with the discontinuous deformation analysis (DDA) method. We also derived the recurrence formula for the creep deformation increment with the time step during numerical simulations. Based on the minimum potential energy principle, the general equilibrium equation was derived, and the shear creep deformation in the structural plane was considered. A numerical program was also developed and its effectiveness was confirmed based on the curves obtained by the creep test of the structural plane of a rock mass under different stress levels. Finally, the program was used to analyze the mechanism responsible for the creep features of the structural plane in the case of the toppling deformation of the rock slope. The results showed that the extended DDA method is an effective one.

Wang, Li, Rui Xu, Ruohua Liu, Peng Ge, Wei Sun, and Mengjie Tian. "Self-Assembly of NaOL-DDA Mixtures in Aqueous Solution: A Molecular Dynamics Simulation Study." Molecules 26, no. 23 (November 24, 2021): 7117. http://dx.doi.org/10.3390/molecules26237117.

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The self-assembly behaviors of sodium oleate (NaOL), dodecylamine (DDA), and their mixtures in aqueous solution were systematically investigated by large-scale molecular dynamics simulations, respectively. The interaction mechanisms between the surfactants, as well as the surfactants and solvent, were revealed via the radial distribution function (RDF), cluster size, solvent-accessible surface area (SASA), hydrogen bond, and non-bond interaction energy. Results showed that the molecules more easily formed aggregates in mixed systems compared to pure systems, indicating higher surface activity. The SASA values of DDA and NaOL decreased significantly after mixing, indicating a tighter aggregation of the mixed surfactants. The RDF results indicated that DDA and NaOL strongly interacted with each other, especially in the mixed system with a 1:1 molar ratio. Compared to van der Waals interactions, electrostatic interactions between the surfactant molecules were the main contributors to the improved aggregation in the mixed systems. Besides, hydrogen bonds were found between NaOL and DDA in the mixed systems. Therefore, the aggregates in the mixed systems were much more compact in comparison with pure systems, which contributed to the reduction of the repulsive force between same molecules. These findings indicated that the mixed NaOL/DDA surfactants had a great potential in application of mineral flotation.

Yan, Xiao Ling, Wang Long Wang, and Nan Xue. "Research and Simulation of an Efficient Circular Interpolation Algorithm." Advanced Materials Research 542-543 (June 2012): 1204–8. http://dx.doi.org/10.4028/www.scientific.net/amr.542-543.1204.

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During the process of conventional DDA circular interpolation, the synthesis feed rate fluctuations often, the machining errors are large also. A new efficient arc interpolation method is proposed in this paper, which uses the principle of DDA circular interpolation, it’s function is optimized and improved, Radius is used as the basis of interpolation feed, the left normalized data and pre-loaded are used also. The simulation result of VB program show that efficient circular interpolation method not only has high efficiency,but also has high accuracy.

Ning, Youjun, Xinyang Lv, and Zheng Yang. "DDA Simulation Study on Mechanical Failure of Heterogenous Rock." Geofluids 2021 (November 26, 2021): 1–11. http://dx.doi.org/10.1155/2021/1416560.

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Heterogeneity is an important characteristic that affects the mechanical behavior of rock. In the present work, a statistical rock mesoheterogeneity model based on the Weibull distribution function is introduced into the discontinuous deformation analysis (DDA) method to simulate the mechanical failure of heterogeneous rock, in which the general heterogeneity degree is controlled by a heterogeneity index and the mechanical property of each subblock element is randomly assigned. Brazilian disc and uniaxial compressive rectangular specimens are simulated as examples. Results show that it is more reasonable to consider the heterogeneity of elasticity properties (the elastic modulus and Poisson’s ratio) and strength properties (the tensile strength, cohesion, and friction angle) simultaneously in the heterogeneity model. It is also shown that with a larger heterogeneity index, which means a lower degree of heterogeneity, the reproducibility of the macroscopic response curves of a specimen gets better, while the exact cracking always differs but with less scattered cracks, and the global fracturing failure pattern and mode are weakly influenced by the heterogeneity. Moreover, with the increase in the heterogeneity index, the macroscopic equivalent modulus and strength get larger and approach those of a homogeneous specimen. This work indicates the importance of heterogeneity for rock mechanical behaviors including the macroscopic equivalent response and the fracturing failure. By the subblock DDA method to simulate fracturing realistically, the fracturing failure process of heterogeneous rock can be successfully reproduced, which builds good foundation for the simulation study of heterogeneous rock fracturing in practical problems, e.g., coal and rock fracturing in fluidization mining in the future.

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Дисертації з теми "DDA simulation":

Alves, Alves Estefania. "Émission de photons dans un microscope à effet tunnel : application à l'étude des propriétés optiques et électroniques de systèmes hybrides métal-semi-conducteur." Electronic Thesis or Diss., Toulouse 3, 2023. http://www.theses.fr/2023TOU30351.

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Les dichalcogénures de métaux de transition (TMD) sont une famille de semi-conducteurs qui présentent un gap direct lorsque leur épaisseur est réduite jusqu'à la monocouche, ce qui leur confère des propriétés optiques et électroniques exceptionnelles, notamment une luminescence avec un rendement élevé. La technique d'émission de lumière dans un microscope à effet tunnel (STM-LE) est utilisée pour étudier l'émission de photons de ces monocouches. Cette technique originale consiste à injecter grâce au courant tunnel des porteurs de charges de manière très locale dans des monocouches de TMD. Cela conduit à la création d'excitons, paires électrons-trous liées par des forces de Coulomb, au sein de la monocouche. Ces excitons vont se désexciter en émettant des photons dont l'énergie correspond au gap direct du semi-conducteur. Ce phénomène de luminescence est mis en évidence expérimentalement en utilisant un microscope STM couplé à un dispositif de détection optique, ce qui permet une analyse de l'émission de photons à la fois sur le plan spectral et spatial avec une résolution nanométrique. Le couplage électromagnétique des monocouches de TMD avec leurs substrats métalliques donne naissance à des structures hybrides métal/semi-conducteur dont les propriétés optiques et électroniques sont étudiées. La nature du substrat (plasmonique ou non) et sa morphologie (uniforme ou nanostructurée) jouent un rôle essentiel tant sur l'intensité que sur la distribution spectrale de la luminescence émise. En effet, lorsque des substrats plasmoniques sont utilisés, le mécanisme d'émission lumineuse implique le couplage électromagnétique entre des modes plasmoniques excités par le courant tunnel et les excitons confinés au sein de la monocouche de TMD. Cette interaction donne lieu à une émission de photons plus efficace. En jouant avec la morphologie de ces substrats, il est possible d'ajuster ce couplage afin d'obtenir une amplification ou une atténuation de l'émission de lumière. Sachant que l'interaction électromagnétique entre plasmons et excitons joue un rôle important dans la luminescence des monocouches dans le cas d'une jonction STM hybride TMD/métal plasmonique, des simulations numériques électromagnétiques sont réalisées via la méthode DDA (Discrete Dipole Approximation). Dans ces simulations, les effets quantiques du courant tunnel sont pris en compte en utilisant le modèle Quantum Corrected Model. Les modes électromagnétiques présents dans la jonction et leur dépendance vis-à-vis des paramètres tunnel (distance pointe-surface et tension de polarisation) sont mis en évidence à partir de la simulation de la réponse optique de la jonction à une onde excitatrice incidente. En particulier, les modes "gap plasmon" et le couplage plasmon-exciton de type Fano se produisant à l'interface entre la monocouche et le substrat plasmonique sont mis en évidence. L'influence de la morphologie du substrat sur les propriétés de ces modes a également été analysée. En s'inspirant des modèles théoriques de l'émission de lumière dans des jonctions STM purement métalliques proposés dans la littérature, un modèle est développé afin d'obtenir des spectres théoriques de luminescence d'une jonction STM hybride TMD/métal plasmonique. Ce modèle prend en compte les propriétés optiques et électroniques de la monocouche, ainsi que le courant tunnel, source d'excitation à l'origine du phénomène de luminescence. De plus, en utilisant les résultats obtenus à partir des simulations numériques, le couplage électromagnétique entre les excitons confinés dans la monocouche de TMD et les plasmons excités dans la nanocavité formée par la configuration pointe-surface du STM est également considéré. Pour finir, l'effet de la morphologie du substrat sur l'émission de lumière est étudié de manière théorique. Ces résultats sont comparés aux résultats expérimentaux afin de valider le modèle présenté
Transition metal dichalcogenides (TMDs) are a family of semiconductors that exhibit a direct bandgap when their thickness is reduced to a monolayer, giving them remarkable optical and electronic properties, including high-efficiency luminescence. Photon emission from these monolayers is investigated using the STM-LE (Light Emission induced by Scanning Tunneling Microscopy) technique. This innovative method involves the localized injection of charge carriers into TMD monolayers through the tunneling current. This process results in the formation of excitons, electron-hole pairs bound by Coulomb forces, within the TMD monolayer. These excitons decay radiatively emitting photons whose energy corresponds to the direct bandgap of the semiconductor. This light emission process is experimentally studied using an STM microscope combined with a light detection system, enabling spectral and spatial analysis of the photon emission with nanometer-scale resolution. The electromagnetic interaction between TMD layers and their metallic substrates leads to the formation of hybrid metal-semiconductor structures, the optical and electronic properties of which are under investigation. The nature of the substrate (plasmonic or non-plasmonic) and its morphology (uniform or nanostructured) play a crucial role in both the intensity and spectral distribution of the emitted photons. Indeed, for plasmonic substrates, the photon emission process involves the electromagnetic coupling between plasmon modes excited by electron tunneling and excitons confined within the TMD monolayer. This interaction leads to an enhancement of the photon emission. Moreover, by tuning the morphology of the substrate, it becomes possible to modify this coupling and thus, the photon emission rate. Considering the significant role of the electromagnetic interaction between plasmon modes and excitons in the luminescence from TMD monolayers within a hybrid TMD/metal-plasmonic STM junction, electromagnetic numerical simulations are carried out using the DDA (Discrete Dipole Approximation) method. These simulations account for electron tunneling using the Quantum Corrected Model. By simulating the optical response of the junction to an incident excitation wave, the electromagnetic modes within the junction and their dependence on the tunneling parameters, such as tip-surface distance and bias voltage, are investigated. In particular, gap plasmon modes and the Fano-type plasmon-exciton coupling at the interface between the monolayer and the plasmon substrate are pointed out. Furthermore, the role of substrate morphology on the properties of these modes is also addressed. Based on theoretical models describing the light emission taking place in purely metallic STM junctions proposed in the literature, a model is developed to compute theoretical light emission spectra for a hybrid TMD/plasmonic-metal STM junction. This model takes into account the optical and electronic properties of the TMD monolayer, and the electron tunneling as the excitation source at the origin of the light emission phenomenon. In addition, using the results obtained from the numerical simulations, the electromagnetic coupling between the excitons confined in the TMD monolayer and the plasmons excited in the nanocavity formed by the tip-surface configuration of the STM is also considered. Finally, the effect of the substrate morphology on the light emission is studied theoretically. These results are compared with the experimental findings in order to validate the model presented

Frenzel, Erik. "Co-Simulation von LIGGGHTS® und SimulationX® zur Simulation des Zerkleinerungsprozesses in Brechern." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-206919.

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In vielen Bereichen der Tagebautechnik spielt die Zerkleinerung von Material/ -strömen eine wesentliche Rolle, wobei sich je nach Material verschiedene Anforderungen an das Brechersystem ergeben. In Folge dessen werden Brecher auftragsspezifisch, meist für einen speziellen Gesteinstyp oder Einsatzort entwickelt oder modifiziert. Eine aussagekräftige Prognose der im Bruchprozess auftretenden Lasten auf den Brecher ist somit essentieller Bestandteil im Entwicklungsprozess. Ein viel versprechender Ansatz, um das Materialverhalten in der Lastprognose zu berücksichtigen, ist die numerische Simulation des Materialbruchverhaltens mit Hilfe der Diskreten-Elemente-Methode (DEM). Das Verhalten der sogenannten Partikel wird über Kontakt- und bond-Modelle beschrieben und soll das makroskopische Verhalten des jeweiligen Gesteins möglichst realitätsnah abbilden. Die Problematik ist, dass in SimulationX® keine Module zur DEM-Simulation vorhanden sind und umgekehrt in der DEM-Simulationsumgebung LIGGGHTSG® (LAMMPS improved for general granular and granular heat transfer simulations) keine derartige Maschinensimulation möglich ist. Der Ausweg ist die Co-Simulation zweier unterschiedlicher Simulationsumgebungen durch die Nutzung des ,,Functional Mock-Up Interface“-Standards (FMI). Berechnungsergebnis sind die dynamischen Lasten auf den Brecher unter Berücksichtigung des Materialverhaltens. Somit können früher in der Brecherentwicklung Prognosen zu auftretenden Lasten getroffen und Einflussuntersuchungen von Maschinenkonfigurationen zur Effizienzsteigerungen durchgeführt werden, was zuvor auf Grund des Einzelanfertigungscharakters nicht möglich oder nicht wirtschaftlich war.

Papapanagiotou, Nikolaos, Eugen Constantin, Sanjeev Singh, and Nikolaos Papapanagiotou. "Analysis of DDD and VDT simulation techniques to determine feasibility of using VDT simulation to validate DDD models." Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/9925.

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Approved for public release; distribution is unlimited.
MBA Professional Report
Approved for public release; distribution is unlimited.
The purpose of this MBA project was to determine whether and how VDT can emulate the results obtained from A2C2 Experiments. To do that, we have first focused on learning the basics of VDT and DDD simulation techniques and then on how the models used in DDD can be analyzed using VDT. To this end, we obtained experimental data from DDD Experiment 8 and created representative models in VDT to determine the similarities and differences. We also kept detailed records of our research to assist individuals in the future who may want to expand on our work. The project involved studying of DDD and VDT techniques, establishing building blocks in VDT, creating a best effort model for DDD Experiment 8 and studying the various outcomes. In this project we could not successfully replicate the complex DDD Experiment 8 scenarios within VDT. However, important conclusions were drawn that would go a long way towards helping future studies in this regard.

Deniz, Ertan. "Dds Based Mil-std-1553b Data Bus Interface Simulation." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614852/index.pdf.

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This thesis describes distributed simulation of MIL-STD-1553B Serial Data Bus interface and protocol based on the Data Distribution Service (DDS) middleware standard. The data bus connects avionics system components and transports information among them in an aircraft. It is important for system designers to be able to evaluate and verify their component interfaces at the design phase. The 1553 serial data bus requires specialized hardware and wiring to operate, thus it is expensive and complex to verify component interfaces. Therefore modeling the bus on commonly available hardware and networking infrastructure is desirable for evaluation and verification of component interfaces. The DDS middleware provides publish-subscribe based communications with a number of QoS (Quality Of Service) attributes. DDS makes it easy to implement distributed systems by providing an abstraction layer over the networking interfaces of the operating systems. This thesis takes the advantage of the DDS middleware to implement a 1553 serial data bus simulation tool. In addition, the tool provides XML based interfaces and scenario definition capabilities, which enable easy and quick testing and validation of component interfaces. Verification of the tool was performed over a case study using a scenario based on the MIL-STD-1760 standard.

Burkhard, Adam. "Komplexe Systeme mit dynamischem, nichtlinearem Verhalten durch Simulation verstehen und optimieren." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-225834.

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Wo FEM- und CFD-Analysen präzise Aussagen über einzelne Bauteile und überschaubare Baugruppen liefern, untersucht die dynamische Systemsimulation zeitveränderliche Vorgänge ganzer Systeme. Diese Systeme können auch aus Komponenten unterschiedlicher physikalischer Domänen bestehen. Somit lassen sich zum Beispiel die Wechselwirkungen und resultierenden Effekte aus Regelstrecken gekoppelt mit mechanischen, hydraulischen und oder elektrischen Strukturen komfortabel in nur einem Modell auf einer Plattform betrachten.

Didoszak, Jarema M. "Parametric studies of DDG-81 ship shock trial simulations." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FDidoszak.pdf.

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Spruegel, Tobias C., and Sandro Wartzack. "Das FEA-Assistenzsystem – Analyseteil FEdelM." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-215130.

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Die simulative Absicherung von Produkten in den frühen Phasen der Produktentwicklung wird immer wichtiger, um den Anforderungen nach steigender Effizienz gerecht zu werden. Da das Angebot an erfahrenen Berechnungsingenieuren mit langjähriger Berufserfahrung begrenzt ist gilt es weniger erfahrene Simulationsanwender bei der Durchführung von aussagekräftigen Finite-Elemente-Simulationen zu unterstützen. Die Autoren stellen im Rahmen des Beitrags das Konzept des Analyseteils FEdelM eines FEA-Assistenzsystems vor, welches strukturmechanische Finite-Elemente (FE) Simulationen auf Plausibilität überprüft und auftretende Fehler möglichst automatisiert zu erkennt und behebt. Hierbei werden die einzelnen Module und deren Verknüpfungen untereinander und zu anderen Anwendungen vorgestellt.

Kleyer, Niklas Carl Simom. "TRAFFIC SIMULATIONS THROUGH ODE-, DDE SYSTEM MODELING AND NUMERICAL COMPUTATIONS." Thesis, KTH, Matematik (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148377.

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This report is written as a project to conclude the three year bachelor part of a five year degree in engineering and will as such target students finishing their three year bachelor degrees. The main topic of this project is traffic simulation through numerical analysis, with the accompanying subtopics time integration, eigenvalue analysis and computation complexity. The tool used through the project is Matlab computational software. This project features two general traffic models where the first is based on a system of ordinary differential equations (ODE’s) and the second one is based on a system of delay differential equations (DDE’s). The project will highlight the implications of driver considerations in terms of stability, stability related to system size, stability related to reaction times and the relation between the large system stability and increasing the (h; k) values of the model. (h; k) values of the model
The ODE- and DDE models are based on the same model with the only exception that the DDE model features reaction times. They are defined by consideration forces and sub-consideration forces. The values (h; k) determines the number of cars that each driver considers and therefore adds to the system as additional terms that are of the same form as the consideration forces, hence the sub prefix. The basic case where there are no sub-considerations involved is called the base case of the system and equals to (h; k) = (1; 1). The (h; k) of the system is determining the matrix B in equation (11) by the number of sub diagonals h and super diagonals k that are filled by weights of the forces. The time integrations can result in three base cases, unstable, stable oscillating and exponentially stable. These cases refer to the behavior of all system velocities. The unstable case can for limited time frames predict collisions between cars but otherwise diverge and cannot generally be used. Oscillating stable systems reach a constant velocity after a settling time and fits well into a realistic scenario. The exponential case reaches a constant velocity the fastest and is therefore the sought after solution. Both models are similar in this regard apart from the fact that the DDE model generally have a lot more system energy. Figures 1 and 4 are empirical proof that the models works as defined and can predict some traffic behavior. An interesting observation during testing was that the ODE exponential case would always remain exponential no matter the multiplication (; ; ) = C(; ; ), the only difference would be the system energy since larger acting forces are coupled with larger energies. The DDE model however is dependent on the system energy for stability since the delay sets a system energy limit for stability since too large forces coupled with delay will not achieve the optimum distance d. The system stability analysis can be reduced in both models to analyzing the homogeneous and particular parts separate. The expansions confirms in both cases what the time integrations shows and can give an idea of how the stability changes with one parameter changing. However, this is where the DDE model behaves completely different from the ODE model. For the ODE case it is possible to plot a complete eigenvalue chart whereas the DDE case has an infinite number of eigenvalues and is therefore impossible to completely chart. A conclusion that is in common between the models is that Fd(t) inherently is dominant and should as such be at lower priority compared to the other consideration forces in order to help system stability. Comparisons to the spring equation revealed that systems that prioritize Fd(t) too high converges to a system of particles in a chain connected by springs with no friction giving the observed behavior. Prioritizing F fr(t) help stability in both cases with the exception that DDE case will be stable for a sub interval (since the top limit comes from the system total energy) within the expansion whereas the ODE case remains stable through the whole intervall. The problems that come with larger systems are stability- and computation complexity related. All through the project has the models focused on the base case with no sub-considerations. The thesis is that adding sub-considerations will again stabilize an unstable system with the addition that each consecutive weight should deflate its value exponentially. The results proves that an unstable system can be stabilized by simply increasing the (h; k) of the system. This can have applications when the optimal weights are not enough to stabilize a large system. When computing the eigenvalues for large systems it puts strain on the algorithm ’eig’. According to [1] is the computation time complexity proportional to n3. What the resulting fit shows is that the relation is more quadratic than cubic and the reason is described to be the appearance of the system matrix for the base case. The matrix structure is similar to the one of the upper Hessenbergs which as a result saves time when transforming the input matrix which is the reason why the complexity is weakly cubic.

PACI, EMANUELE. "Etude dea proteines a haute pression hydrostatique par simulation de dynamique moleculaire." Paris 6, 1996. http://www.theses.fr/1996PA066750.

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Cette these est une etude des proteines soumises a des pressions elevees, par des simulations de dynamique moleculaire. Le but de cette these est d'approfondir la comprehension du comportement des proteines a l'echelle atomique et moleculaire et d'aller plus loin dans l'analyse de certains resultats experimentaux. Afin d'etablir la faisabilite de simulations a haute pression pour des macromolecules biologiques, differentes methodes de simulation de dynamique moleculaire a pression et temperature constantes sont mises en oeuvre et comparees. Ces techniques sont utilisees pour examiner les modifications de structure et de volume de deux proteines globulaires, la superoxyde dismutase en solution et le lysozyme en phase cristalline, a haute pression. On etudie la surface accessible au solvant et le volume contenu dans cette surface car ces quantites jouent un role important dans la description des proteines, dans l'etude de leur interaction avec le solvant et de la stabilite des differentes conformations. Les points centrales de ce travail sont la comparaison de differentes definitions de surface et volume d'une proteine et l'interpretation de mesures experimentales de compressibilite.

Hering, Klaus. "Parallel Cycle Simulation." Universität Leipzig, 1996. https://ul.qucosa.de/id/qucosa%3A34504.

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Parallelization of logic simulation on register-transfer and gate level is a promising way to accelerate extremely time extensive system simulation processes for whole processor structures. In this report parallel simulation realized by means of the functional simulator parallel- TEXSIM based on the clock-cycle algorithm is considered. Within a corresponding simulation, several simulator instances co-operate over a loosely-coupled processor system, each instance simulating a part of a synchronous hardware design. Therefore, in preparation of parallel simulation, partitioning of hardware models is necessary, which is essentially determining e±ciency of the following simulation. A framework of formal concepts for an abstract description of parallel cycle simulation is developed. This provides the basis for partition valuation within partitioning algorithms. Starting from the definition of a Structural Hardware Model as special bipartite graph Sequential Cycle Simulation is introduced as sequence of actions. Following a cone-based partitioning approach a Parallel Structural Hardware Model is defined as set of Structural Hardware Models. Furthermore, a model of parallel computation called Communicating Processors is introduced which is closely related to the well known LogP Model. Together with the preceding concepts it represents the basis for determining Parallel Cycle Simulation as sequence of action sets.

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Книги з теми "DDA simulation":

K, Garcia Sharon, Armstrong Laboratory (U.S.), and Systems Engineering Associates, eds. Desktop Decision Training (DDT) system design document. Brooks Air Force Base, Tex: Armstrong Laboratory, Air Force Materiel Command, 1996.

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J, Yardley Roland, ed. DDG-51 engineering training: How simulators can help. Santa Monica, CA: RAND, 2009.

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J, Yardley Roland, ed. DDG-51 engineering training: How simulators can help. Santa Monica, CA: RAND, 2009.

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J, Yardley Roland, ed. DDG-51 engineering training: How simulators can help. Santa Monica, CA: RAND, 2009.

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K, Garcia Sharon, Armstrong Laboratory (U.S.), and Systems Engineering Associates, eds. Desktop Decision Training (DDT) system requirements document. Brooks Air Force Base, Tex: Armstrong Laboratory, Air Force Materiel Command, 1996.

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International Forum on Discontinuous Deformation Analysis and Simulations of Discontinuous Media (1st 1996 Berkeley, Calif.). Discontinuous deformation analysis (DDA) and simulations of discontinuous media: Proceedings of the first International Forum on Discontinuous Deformation Analysis (DDA) and Simulations of Discontinuous Media, Berkeley, California, USA, June 12-14, 1996. Albuquerque, N.M: TSI Press, 1996.

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1938-, Beveridge David L., and Lavery Richard, eds. Theoretical biochemistry & molecular biophysics. Schenectady, NY: Adenine Press, 1991.

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International, Conference on Electrophoresis Supercomputing and the Human Genome (1st 1990 Tallahassee Florida). The First International Conference on Electrophoresis, Supercomputing, and the Human Genome: Proceedings of the April 10-13 conference at Florida State University, Tallahassee, Florida. Singapore: World Scientific, 1991.

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D, Neilson, Das M. P, and Gordon Godfrey International Workshop on Computational Approaches to Novel Condensed Matter Systems (3rd : 1993 : Sydney, N.S.W.), eds. Computational approaches to novel condensed matter systems: Applications to classical and quantum systems. New York: Plenum Press, 1995.

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Gordon Godfrey International Workshop on Computational Approaches to Novel Condensed Matter Systems (3rd 1993 Sydney, Australia). Computational approaches to novel condensed matter systems: Applications to classical and quantum mechanics. New York: Plenum, 1995.

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Частини книг з теми "DDA simulation":

Yang, Qingqing, Fei Cai, Keizo Ugai, Zhiman Su, and Lingyu Xu. "Numerical Simulation of Granular Flows by DDA." In Earthquake-Induced Landslides, 643–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-32238-9_69.

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Xia, Mingyao, and Guangqi Chen. "Simulation of Crack Initiation and Propagation Using the Improved DDA." In Lecture Notes in Civil Engineering, 327–35. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0077-7_30.

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Liu, Feng, Kaiyu Zhang, and Kaiwen Xia. "New Bond Model in Disk-Based DDA for Rock Failure Simulation." In Springer Series in Geomechanics and Geoengineering, 381–85. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97112-4_85.

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Camargo, Manuel, Marlon Dumas, and Oscar González-Rojas. "Learning Accurate Business Process Simulation Models from Event Logs via Automated Process Discovery and Deep Learning." In Advanced Information Systems Engineering, 55–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-07472-1_4.

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AbstractBusiness process simulation is a well-known approach to estimate the impact of changes to a process with respect to time and cost measures – a practice known as what-if process analysis. The usefulness of such estimations hinges on the accuracy of the underlying simulation model. Data-Driven Simulation (DDS) methods leverage process mining techniques to learn process simulation models from event logs. Empirical studies have shown that, while DDS models adequately capture the observed sequences of activities and their frequencies, they fail to accurately capture the temporal dynamics of real-life processes. In contrast, generative Deep Learning (DL) models are better able to capture such temporal dynamics. The drawback of DL models is that users cannot alter them for what-if analysis due to their black-box nature. This paper presents a hybrid approach to learn process simulation models from event logs wherein a (stochastic) process model is extracted via DDS techniques, and then combined with a DL model to generate timestamped event sequences. An experimental evaluation shows that the resulting hybrid simulation models match the temporal accuracy of pure DL models, while partially retaining the what-if analysis capability of DDS approaches.

Engel, Megan Clare. "Simulation Methods." In DNA Systems Under Internal and External Forcing, 19–24. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-25413-1_2.

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Spedalieri, Antonietta, Israel Martín-Escalona, and Francisco Barcelo. "Simulation Analysis of Teletraffic Variables in DCA Cellular Networks." In Universal Multiservice Networks, 540–53. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-30197-4_53.

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Majumder, Urmi, Sudheer Sahu, Thomas H. LaBean, and John H. Reif. "Design and Simulation of Self-repairing DNA Lattices." In DNA Computing, 195–214. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11925903_15.

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Ibershoff, Joseph, Jerzy W. Jaromczyk, and Danny van Noort. "Simulations of Microreactors: The Order of Things." In DNA Computing, 286–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11925903_22.

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Pescini, Dario, Daniela Besozzi, Claudio Zandron, and Giancarlo Mauri. "Analysis and Simulation of Dynamics in Probabilistic P Systems." In DNA Computing, 236–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11753681_19.

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Hartemink, Alexander, and David Gifford. "Thermodynamic simulation of deoxyoligonucleotide hybridization for DNA computation." In DNA Based Computers III, 25–37. Providence, Rhode Island: American Mathematical Society, 1999. http://dx.doi.org/10.1090/dimacs/048/02.

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Тези доповідей конференцій з теми "DDA simulation":

Arif, Khalid Mahmood, Johan Potgieter, and Olaf Diegel. "Simulation of nanoparticle enhanced diffraction grating biosensor using DDA." In 2013 IEEE 4th International Conference on Photonics (ICP). IEEE, 2013. http://dx.doi.org/10.1109/icp.2013.6687134.

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Zhu, Jianye, Yiguo Xue, Yufan Tao, Kai Zhang, Zhiqiang Li, Xuedong Zhang, and Ying Yang. "The numerical simulation on the stability of steep rock slope by DDA." In MATERIALS SCIENCE, ENERGY TECHNOLOGY, AND POWER ENGINEERING I: 1st International Conference on Materials Science, Energy Technology, Power Engineering (MEP 2017). Author(s), 2017. http://dx.doi.org/10.1063/1.4982499.

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Ning, Y. J., J. Yang, G. W. Ma, and P. W. Chen. "DDA for Dynamic Failure Problems and Its Application in Rock Blasting Simulation." In 9th International Conference On Analysis of Discontinues Deformation: New Developments and Applications. Singapore: Research Publishing Services, 2009. http://dx.doi.org/10.3850/9789810844554-0010.

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Chen, Guangqi, Lu Zheng, Yingbin Zhang, Simeng Dong, Yasuo Kasugai, and Tsukasa Kawakami. "Stability Analysis of Breakwater Under Seepage Flow Using DDA." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11605.

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In order to explain the mechanism of breakwater failure destroyed by the massive tsunami triggered by the 2011 off the Pacific coast of Tohoku Earthquake, a failure mode is presented from the view of geotechnical engineering by considering the seepage force rather than the failure modes by using the existing failure mechanisms released in Coastal Engineering. It is proposed that a pseudo-steady state flow condition inside of the rubble mound can be created by high hydraulic head difference, which becomes possible due to the behaviour of the long period of tsunami wave. At first, a piping initiated local failure model is proposed and the phenomenon of piping initiated failure by laboratory model experiments is re-enacted. Also, the piping-initiated local failure of a breakwater is re-enacted by DDA simulation. And then, DDA is applied to the stability analysis of breakwater under seepage flow with new proposed displacement based failure criteria which can consider both global and local failure. A relationship between the height of a tsunami with the safety factor of a breakwater has been obtained. The results have been validated by both the laboratory model experiments and comparison with simplified Bishop Method.

Aiqing, Wu, Yang Qigui, Ma Guisheng, Lu Bo, and Li Xiaojun. "Study on the Formation Mechanism of Tanjiashan Landslide Triggered by Wenchuan Earthquake Using DDA Simulation." In 9th International Conference On Analysis of Discontinues Deformation: New Developments and Applications. Singapore: Research Publishing Services, 2009. http://dx.doi.org/10.3850/9789810844554-keynote-wu-aiqing.

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KAIDI, Sami, Abdellatif OUAHSINE, Mohamed ROUAINIA, François HISSEL, and Philippe SERGENT. "Simulation de la stabilité des digues en enrochement par la méthode d'Analyse de Déformations Discontinues (DDA)." In Journées Nationales Génie Côtier - Génie Civil. Editions Paralia, 2010. http://dx.doi.org/10.5150/jngcgc.2010.083-k.

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Ye, W., and S. Mukherjee. "Design and Fabrication of an Electrostatic Variable Gap Comb Drive in Micro-Electro-Mechanical Systems." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1297.

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Abstract Polynomial driving-force comb drives are synthesized using numerical simulation. The electrode shapes are obtained using the indirect boundary element method. Variable gap comb drives that produce combinations of linear, quadratic, and cubic driving-force profiles are synthesized. This inverse problem is solved by an optimization procedure. Sensitivity analysis is carried out by the direct differentiation approach (DDA) in order to compute design sensitivity coefficients (DSCs) of force profiles with respect to parameters that define the shapes of the fingers of a comb drive. The DSCs are then used to drive iterative optimization procedures. Designs of variable gap comb drives with linear, quadratic and cubic driving force profiles are presented in this paper. Based on these designs, a comb drive which produces cubic polynomial driving force has been fabricated using the SCREAM I process.

Parviainen, Hannu, and Kari Lumme. "Light Scattering from Rough Thin Films: DDA Simulations." In Tenth Conference on Electromagnetic and Light Scattering. Connecticut: Begellhouse, 2007. http://dx.doi.org/10.1615/ichmt.2007.confelectromagligscat.410.

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Caldwell, Niall. "Review of Early Work on Digital Displacement® Hydrostatic Transmission Systems." In BATH/ASME 2018 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fpmc2018-8922.

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The paper describes the work done by the author (1) from 1999 to 2006 to develop the Digital Displacement Pump (DDP) and Pump/Motor (DDPM) and demonstrate the feasibility of off-highway vehicle applications. The link between DDPM capacity and the solenoid valve performance was identified. Magnetic geometry was improved by parametric FEA, then time-domain behavior was improved with a hybrid FEA/lumped-parameter model. Software improvements allowed variable speed and bidirectional operation, enabling the demonstration of the first Digital Displacement Transmission (DDT) systems on a vehicle, one featuring a load-sensing DDP and secondary control by DDPM displacement, and one featuring primary control by DDP displacement and a conventional axial motor. A time-domain simulation was created of the primary-controlled vehicle, which yielded good comparison to experimental results. The deterministic nature of the DDP lends itself to model-based system design methods, which have since been used to develop larger commercial systems. The first detailed analysis of DDP efficiency characteristics revealed profound differences to conventional variable displacement pumps, including exceptional part-load efficiency and the dominant effect of fluid compressibility. A peak overall efficiency of 97% was recorded for a DDP after analysis of loss sources prompted design improvement.

Irie, K., T. Koyama, E. Hamasaki, S. Nishiyama, K. Shimaoka, and Y. Ohnishi. "DDA Simulations for Huge Landslides in Aratozawa Area, Miyagi, Japan Caused by Iwate-Miyagi Nairiku Earthquake." In 9th International Conference On Analysis of Discontinues Deformation: New Developments and Applications. Singapore: Research Publishing Services, 2009. http://dx.doi.org/10.3850/9789810844554-0057.

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Звіти організацій з теми "DDA simulation":

Constantin, Eugen, Nikolaos Papapanagiotou, and Sanjeev Singh. Analysis of DDD and VDT Simulation Techniques to Determine Feasibility of Using VDT Simulation to Validate DDD Models. Fort Belvoir, VA: Defense Technical Information Center, June 2004. http://dx.doi.org/10.21236/ada424673.

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Martinez, Michael. Open Data Distribution Service (DDS) for Use in a Real Time Simulation Laboratory Environment. Fort Belvoir, VA: Defense Technical Information Center, February 2012. http://dx.doi.org/10.21236/ada557628.

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Reaugh, J. E. HERMES Model Developments and Status to Support Simulations and Analyses of XDT and DDT. Office of Scientific and Technical Information (OSTI), December 2014. http://dx.doi.org/10.2172/1179124.

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Michaud, Pierre-Carl, Louis Lévesque, Marcelin Joanis, Jonathan Brasseur, and Quentin Winstel. Plan québécois des infrastructures : comparaison interprovinciale et soutenabilité. CIRANO, November 2023. http://dx.doi.org/10.54932/lxou3345.

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La dynamique actuelle des investissements en infrastructures du gouvernement du Québec est-elle soutenable ? Pour répondre à cette question, il importe dans un premier temps d’analyser la vraisemblance que la tendance actuelle se maintienne (ou non) dans le futur. Dans cette optique, nous présentons des comparaisons interprovinciales et en analysant la dynamique des investissements à travers le prisme de son impact sur l’état des infrastructures tel que mesuré notamment par le déficit de maintien d’actifs (DMA). Dans un second temps, il faut intégrer ce que l’on sait de la dynamique des infrastructures dans une analyse de soutenabilité budgétaire. Nos résultats de simulation montrent une augmentation continue du DMA. La dynamique actuelle n’est donc pas soutenable sur cette base. Nos résultats montrent également que la réduction du DMA entraîne un arbitrage avec l’objectif de soutenabilité budgétaire.

Zbib, Hussein M., Dongsheng Li, Xin Sun, and Mohammad A. Khaleel. Large Scale DD Simulation Results for Crystal Plasticity Parameters in Fe-Cr And Fe-Ni Systems. Office of Scientific and Technical Information (OSTI), April 2012. http://dx.doi.org/10.2172/1062515.

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Roye, Thorsten. Unsettled Technology Areas in Deterministic Assembly Approaches for Industry 4.0. SAE International, August 2021. http://dx.doi.org/10.4271/epr2021018.

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Increased production rates and cost reduction are affecting manufacturing in all sectors of the mobility industry. One enabling methodology that could achieve these goals in the burgeoning “Industry 4.0” environment is the deterministic assembly (DA) approach. The DA approach is defined as an optimized assembly process; it always forms the same final structure and has a strong link to design-for-assembly and design-for-automation methodologies. It also looks at the whole supply chain, enabling drastic savings at the original equipment manufacturer (OEM) level by reducing recurring costs and lead time. Within Industry 4.0, DA will be required mainly for the aerospace and the space industry, but serves as an interesting approach for other industries assembling large and/or complex components. In its entirety, the DA approach connects an entire supply chain—from part manufacturing at an elementary level to an OEM’s final assembly line level. Addressing the whole process of aircraft design and manufacturing is necessary to develop further collaboration models between OEMs and the supply chain, including addressing the most pressing technology challenges. Since all parts aggregate at the OEM level, the OEM—as an integrator of all these single parts—needs special end-to-end methodologies to drastically decrease cost and lead time. This holistic approach can be considered in part design as well (in the design-for-automation and design-for-assembly philosophy). This allows for quicker assembly at the OEM level, such as “part-to-part” or “hole-to-hole” approaches, versus traditional, classical assembly methods like manual measurement or measurement-assisted assembly. In addition, it can increase flexibility regarding rate changes in production (such as those due to pandemic- or climate-related environmental challenges). The standardization and harmonization of these areas would help all industries and designers to have a deterministic approach with an end-to-end concept. Simulations can easily compare possible production and assembly steps with different impacts on local and global tolerances. Global measurement feedback needs high-accuracy turnkey solutions, which are very costly and inflexible. The goal of standardization would be to use Industry 4.0 feedback and features, as well as to define several building blocks of the DA approach as a one-way assembly (also known as one-up assembly, or “OUA”), false one-way assembly, “Jig-as-Master,” etc., up to the hole-to-hole assembly approach. The evolution of these assembly principles and the link to simulation approaches are undefined and unsolved domains; they are discussed in this report. They must be discussed in greater depth with aims of (first) clarifying the scope of the industry-wide alignment needs and (second) prioritizing the issues requiring standardization. NOTE: SAE EDGE™ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies of interest to the mobility industry. The goal of SAE EDGE™ Research Reports is to stimulate discussion and work in the hope of promoting and speeding resolution of identified issues. SAE EDGE™ Research Reports are not intended to resolve the challenges they identify or close any topic to further scrutiny.

Rodriguez Muxica, Natalia. Open configuration options Bioinformatics for Researchers in Life Sciences: Tools and Learning Resources. Inter-American Development Bank, February 2022. http://dx.doi.org/10.18235/0003982.

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The COVID-19 pandemic has shown that bioinformatics--a multidisciplinary field that combines biological knowledge with computer programming concerned with the acquisition, storage, analysis, and dissemination of biological data--has a fundamental role in scientific research strategies in all disciplines involved in fighting the virus and its variants. It aids in sequencing and annotating genomes and their observed mutations; analyzing gene and protein expression; simulation and modeling of DNA, RNA, proteins and biomolecular interactions; and mining of biological literature, among many other critical areas of research. Studies suggest that bioinformatics skills in the Latin American and Caribbean region are relatively incipient, and thus its scientific systems cannot take full advantage of the increasing availability of bioinformatic tools and data. This dataset is a catalog of bioinformatics software for researchers and professionals working in life sciences. It includes more than 300 different tools for varied uses, such as data analysis, visualization, repositories and databases, data storage services, scientific communication, marketplace and collaboration, and lab resource management. Most tools are available as web-based or desktop applications, while others are programming libraries. It also includes 10 suggested entries for other third-party repositories that could be of use.

Semiga and Tiku. PR-214-104505-R02 Improved Methods for Estimating Remaining Fatigue Life of ERW Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 2015. http://dx.doi.org/10.55274/r0010204.

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While the general fracture mechanics methodology for calculating fatigue life is well documented and validated, its application in the definition of pipeline system fatigue lives have differed from field experience. The source and magnitude of the conservatism inherent in the calculated fatigue life estimates are a concern when establishing integrity management programs. Of particular interest are the fatigue life estimates used in the integrity management programs for ERW pipeline systems that are primarily concerned with pipe wall anomalies oriented along the pipe axis. This project was initiated to consider several elements of the fatigue life estimation process to identify if there were sources of conservatism that could be better managed to permit integrity management programs to produce life estimates with known levels of conservatism. The project considered: - Ovality and misalignment stress concentration factors; - Fatigue crack growth rate (da/dN) material performance; and - Bulging correction factor. Both experimental and numerical simulation techniques were used to consider the impact of these factors on rate of fatigue crack growth of pipeline axially oriented defects. The project results were compared to existing codified treatments to quantify the level of conservatism inherent in the current state of practice. Recommendations were provided to enhance the precision and manage conservatism in fatigue crack growth rate calculations used in integrity management. This work has a related webinar.

Crowley, David E., Dror Minz, and Yitzhak Hadar. Shaping Plant Beneficial Rhizosphere Communities. United States Department of Agriculture, July 2013. http://dx.doi.org/10.32747/2013.7594387.bard.

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PGPR bacteria include taxonomically diverse bacterial species that function for improving plant mineral nutrition, stress tolerance, and disease suppression. A number of PGPR are being developed and commercialized as soil and seed inoculants, but to date, their interactions with resident bacterial populations are still poorly understood, and-almost nothing is known about the effects of soil management practices on their population size and activities. To this end, the original objectives of this research project were: 1) To examine microbial community interactions with plant-growth-promoting rhizobacteria (PGPR) and their plant hosts. 2) To explore the factors that affect PGPR population size and activity on plant root surfaces. In our original proposal, we initially prqposed the use oflow-resolution methods mainly involving the use of PCR-DGGE and PLFA profiles of community structure. However, early in the project we recognized that the methods for studying soil microbial communities were undergoing an exponential leap forward to much more high resolution methods using high-throughput sequencing. The application of these methods for studies on rhizosphere ecology thus became a central theme in these research project. Other related research by the US team focused on identifying PGPR bacterial strains and examining their effective population si~es that are required to enhance plant growth and on developing a simulation model that examines the process of root colonization. As summarized in the following report, we characterized the rhizosphere microbiome of four host plant species to determine the impact of the host (host signature effect) on resident versus active communities. Results of our studies showed a distinct plant host specific signature among wheat, maize, tomato and cucumber, based on the following three parameters: (I) each plant promoted the activity of a unique suite of soil bacterial populations; (2) significant variations were observed in the number and the degree of dominance of active populations; and (3)the level of contribution of active (rRNA-based) populations to the resident (DNA-based) community profiles. In the rhizoplane of all four plants a significant reduction of diversity was observed, relative to the bulk soil. Moreover, an increase in DNA-RNA correspondence indicated higher representation of active bacterial populations in the residing rhizoplane community. This research demonstrates that the host plant determines the bacterial community composition in its immediate vicinity, especially with respect to the active populations. Based on the studies from the US team, we suggest that the effective population size PGPR should be maintained at approximately 105 cells per gram of rhizosphere soil in the zone of elongation to obtain plant growth promotion effects, but emphasize that it is critical to also consider differences in the activity based on DNA-RNA correspondence. The results ofthis research provide fundamental new insight into the composition ofthe bacterial communities associated with plant roots, and the factors that affect their abundance and activity on root surfaces. Virtually all PGPR are multifunctional and may be expected to have diverse levels of activity with respect to production of plant growth hormones (regulation of root growth and architecture), suppression of stress ethylene (increased tolerance to drought and salinity), production of siderophores and antibiotics (disease suppression), and solubilization of phosphorus. The application of transcriptome methods pioneered in our research will ultimately lead to better understanding of how management practices such as use of compost and soil inoculants can be used to improve plant yields, stress tolerance, and disease resistance. As we look to the future, the use of metagenomic techniques combined with quantitative methods including microarrays, and quantitative peR methods that target specific genes should allow us to better classify, monitor, and manage the plant rhizosphere to improve crop yields in agricultural ecosystems. In addition, expression of several genes in rhizospheres of both cucumber and whet roots were identified, including mostly housekeeping genes. Denitrification, chemotaxis and motility genes were preferentially expressed in wheat while in cucumber roots bacterial genes involved in catalase, a large set of polysaccharide degradation and assimilatory sulfate reduction genes were preferentially expressed.

Guidati, Gianfranco, and Domenico Giardini. Verbundsynthese «Geothermie» des NFP «Energie». Swiss National Science Foundation (SNSF), January 2020. http://dx.doi.org/10.46446/publikation_nfp70_nfp71.2020.4.de.

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Die oberflächennahe Geothermie mit Wärmepumpen ist Stand der Technik und in der Schweiz bereits stark verbreitet. Im künftigen Energiesystem soll zusätzlich die mitteltiefe bis tiefe Geothermie (1–6 km) eine wichtige Rolle spielen. Im Vordergrund steht die Lieferung von Wärme für Gebäude und industrielle Prozesse. Diese Form der Erdwärmenutzung setzt einen gut durchlässigen Untergrund voraus, damit ein Fluid – in der Regel Wasser – die natürlich vorhandene Gesteinswärme übernehmen und an die Oberfläche transportieren kann. Bei Sedimentgesteinen ist dies meist von Natur aus gegeben, wogegen bei Graniten und Gneisen die Durchlässigkeit mittels Einpressen von Wasser künstlich herbeigeführt werden muss. Die so gewonnene Wärme nimmt mit zunehmender Bohrtiefe zu: In 1 km Tiefe liegt die Untergrundtemperatur bei ca. 40 °C und in 3 km Tiefe bei ca. 100 °C. Um eine Dampfturbine für die Stromproduktion anzutreiben, sind Temperaturen von über 100 °C notwendig. Da dafür grössere Tiefen von 3 bis 6 km erforderlich sind, steigt auch das Risiko der durch die Bohrungen induzierten Seismizität. Der Untergrund eignet sich ausserdem auch zur Speicherung von Wärme und Gasen, zum Beispiel Wasserstoff oder Methan, sowie zur definitiven Einlagerung von CO2. Dazu muss er ähnliche Voraussetzungen erfüllen wie bei der Wärmegewinnung, zusätzlich ist jedoch eine über dem Reservoir liegende dichte Deckschicht erforderlich, damit das Gas nicht entweichen kann. Im Verbundprojekt «Wasserkraft und Geothermie» des NFP «Energie» wurde vor allem der Frage nachgegangen, wo sich in der Schweiz geeignete Bodenschichten finden, die die Anforderungen der verschiedenen Nutzungen optimal erfüllen. Ein zweiter Forschungsschwerpunkt betraf Massnahmen zur Reduktion der durch Tiefenbohrungen induzierten Seismizität und der daraus folgenden Schäden an Bauten. Im Weiteren wurden Modelle und Simulationen entwickelt, die zu einem besseren Verständnis der Vorgänge im Untergrund bei der Erschliessung und Nutzung der geothermischen Ressourcen beitragen. Zusammengefasst zeigen die Forschungsergebnisse, dass in der Schweiz gute Voraussetzungen vorhanden sind für die Nutzung der mitteltiefen Erdwärme (1–3 km), sowohl für den Gebäudepark als auch für industrielle Prozesse. Auch in Bezug auf die saisonale Speicherung von Wärme und Gasen ist Optimismus angebracht. Die Potenziale für die definitive Einlagerung von CO2 in relevanten Mengen sind demgegenüber als eher limitiert zu bezeichnen. Hinsichtlich der Stromproduktion aus Erdwärme mittels der tiefen Geothermie (> 3 km) besteht noch keine abschliessende Gewissheit, wie gross das wirtschaftlich nutzbare Potenzial im Untergrund wirklich ist. Diesbezüglich sind dringend industriell betriebene Demonstrationsanlagen notwendig, um die Akzeptanz bei der Bevölkerung und bei Investoren zu stärken.