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  • 1
    Online-Ressource
    Online-Ressource
    Cambridge :Cambridge University Press,
    Schlagwort(e): Geophysics--Fluid models. ; Electronic books.
    Beschreibung / Inhaltsverzeichnis: Geophysical fluid dynamics illustrates the rich interplay between mathematical analysis, nonlinear dynamics, statistical theories, qualitative models and numerical simulations. This self-contained introduction will suit a multi-disciplinary audience ranging from beginning graduate students to senior researchers. It is the first book following this approach and contains many recent ideas and results.
    Materialart: Online-Ressource
    Seiten: 1 online resource (565 pages)
    Ausgabe: 1st ed.
    ISBN: 9780511167584
    DDC: 550
    Sprache: Englisch
    Anmerkung: Cover -- Half-title -- Title -- Copyright -- Contents -- Preface -- 1 Barotropic geophysical flows and two-dimensional fluid flows: elementary introduction -- 1.1 Introduction -- 1.2 Some special exact solutions -- Fourier series tool kit -- 1.2.1 Exact solutions for the Euler equations -- 1.2.2 Exact solutions with beta-effect and generalized Kolmogorov forcing -- 1.2.3 Rossby waves -- 1.2.4 Topographic effect in steady states -- 1.2.5 A dynamical solution with beta-plane and layered topography -- 1.2.6 Beta-plane dynamics with large-scale shear flow -- A test problem for dissipative mechanisms -- 1.3 Conserved quantities -- 1.3.1 Conservation of energy -- Conservation of energy for periodic flows -- 1.3.2 Large-scale and small-scale flow interaction via topography -- 1.3.3 Infinite number of conserved quantities - generalized enstrophy -- 1.3.4 Several conserved quantities -- 1.3.5 Summary of conserved quantities: periodic geometry -- 1.4 Barotropic geophysical flows in a channel domain - an important physical model -- 1.4.1 The impulse and conserved quantities -- 1.4.2 Conservation of circulation -- 1.4.3 Summary of conserved quantities: channel geometry -- 1.5 Variational derivatives and an optimization principle for elementary geophysical solutions -- 1.5.1 Some important variational derivatives -- 1.5.2 An optimization principle for elementary geophysical solutions -- 1.6 More equations for geophysical flows -- 1.6.1 The models -- 1.6.2 Relationships between various models -- Derivation of the barotropic one-layer model from the continuously stratified model -- Derivation of the two-layer model from the continuously stratified model -- Derivation of the one- and one-half-layer model from the two-layer model -- Derivation of the barotropic quasi-geostrophic model from the F-plane model -- References -- 2 The response to large-scale forcing. , 2.1 Introduction -- A remarkable identity -- 2.2 Non-linear stability with Kolmogorov forcing -- 2.2.1 Non-linear stability in restricted sense -- 2.2.2 Finite-dimensional dynamics on the ground modes and non-linear stability -- Fourier representation for the dynamic equations -- 2.2.3 Counter-example of unstable ground state modes dynamics for truncated inviscid flows -- 2.3 Stability of flows with generalized Kolmogorov forcing -- References -- 3 The selective decay principle for basic geophysical flows -- 3.1 Introduction -- 3.2 Selective decay states and their invariance -- 3.3 Mathematical formulation of the selective decay principle -- The Rossby waves degenerate into generalized Taylor vortices in the absence of the geophysical beta-plane effect. -- 3.4 Energy-enstrophy decay -- 3.5 Bounds on the Dirichlet quotient, A (t) -- 3.6 Rigorous theory for selective decay -- 3.6.1 Convergence to an asymptotic state -- 3.6.2 Convergence to the selective decay state -- 3.6.3 Stability of the selective decay states -- 3.6.4 Underlying simplifying mechanisms -- 3.7 Numerical experiments demonstrating facets of selective decay -- 3.7.1 Measure of anisotropy -- 3.7.2 Explicit solutions of the sinh-Poisson equation -- 3.7.3 Numerical examples -- References -- Appendix 1 Stronger controls on A (t) -- Appendix 2 The proof of the mathematical form of the selective decay principle in the presence of the beta-plane effect -- 4 Non-linear stability of steady geophysical flows -- 4.1 Introduction -- 4.2 Stability of simple steady states -- 4.2.1 Non-linear stability and the energy method -- 4.2.2 Simple states with topography, but no mean flow or beta-effect -- 4.2.3 Simple states with topography, mean flow, and beta-effect -- 4.3 Stability for more general steady states -- 4.4 Non-linear stability of zonal flows on the beta-plane. , 4.5 Variational characterization of the steady states -- References -- 5 Topographic mean flow interaction, non-linear instability, and chaotic dynamics -- 5.1 Introduction -- 5.2 Systems with layered topography -- 5.2.1 Hamiltonian structure -- 5.3 Integrable behavior -- 5.3.1 The case h = 0 -- 5.3.2 The case Beta = 0 -- 5.3.3 Single mode topography -- 5.4 A limit regime with chaotic solutions -- 5.4.1 Single mode topography -- 5.4.2 Interaction of non-linear resonances -- 5.4.3 Two modes in the topography: a perturbative Melnikov analysis -- 5.5 Numerical experiments -- 5.5.1 Perturbation of single mode topography -- 5.5.2 Two-mode layered topography and topographic blocking events -- 5.5.3 Random perturbations with multi-mode topography -- 5.5.4 Symmetry breaking perturbations and topographic blocking events -- References -- Appendix 1 -- Appendix 2 -- 6 Introduction to information theory and empirical statistical theory -- 6.1 Introduction -- 6.2 Information theory and Shannon's entropy -- 6.3 Most probable states with prior distribution -- 6.4 Entropy for continuous measures on the line -- 6.4.1 Continuous measure on the line -- 6.4.2 Entropy and maximum entropy principle -- 6.4.3 Coarse graining and loss of information -- 6.4.4 Relative entropy as a "distance" function -- 6.4.5 Information theory and the finite-moment problem for probability measures -- 6.5 Maximum entropy principle for continuous fields -- 6.6.1 The Prior distribution -- 6.6.2 Constraints on the potential vorticity distribution -- 6.6.3 Statistical predictions of the maximum entropy principle -- 6.6.4 Determination of the multipliers and geophysical effect -- 6.7 Application of the maximum entropy principle to geophysical flows with topography and mean flow -- 6.7.1 One-point statistics for potential vorticity and large-scale mean velocity and Shannon entropy. , 6.7.2 The constraints on the one-point statistics -- 6.7.3 Maximum entropy principle and statistical prediction -- 6.7.4 Determination of the multipliers and geophysical effects -- References -- 7 Equilibrium statistical mechanics for systems of ordinary differential equations -- 7.1 Introduction -- 7.2 Introduction to statistical mechanics for ODEs -- 7.2.1 The Liouville property -- 7.2.2 Evolution of probability measures and the Liouville equation -- 7.2.3 Conserved quantities and their ensemble averages -- 7.2.4 Shannon entropy and the maximum entropy principle -- 7.2.5 The most probable state and Gibbs measure -- 7.2.6 Ergodicity and time averaging -- 7.2.7 A simple example violating the Liouville property -- 7.3 Statistical mechanics for the truncated Burgers-Hopf equations -- 7.3.1 The truncated Burgers-Hopf systems and their conserved quantities -- 7.3.2 The Liouville property -- 7.3.3 The Gibbs measure and the prediction of equipartition of energy -- 7.3.4 Numerical evidence of the validity of the statistical theory -- 7.3.5 Truncated Burgers-Hopf equation as a model with statistical features in common with atmosphere -- A scaling theory for temporal correlations -- Numerical evidence for the correlation scaling theory -- 7.4 The Lorenz 96 model -- 7.4.1 Geophysical properties of the Lorenz 96 model -- Rossby waves -- 7.4.2 Equilibrium statistical theory for the undamped unforced L-96 model -- 7.4.3 Statistical properties of the damped forced and undamped unforced L96 models -- Rescaling the damped forced L96 model -- Linear stability of the mean state -- The bulk behavior of the rescaled problem -- The climatology of different forcing regimes in rescaled coordinates -- References -- 8 Statistical mechanics for the truncated quasi-geostrophic equations -- 8.1 Introduction -- 8.2 The finite-dimensional truncated quasi-geostrophic equations. , 8.2.1 The spectrally truncated quasi-geostrophic equations -- 8.2.2 Conserved quantities for the truncated system -- 8.2.3 Non-linear stability of some exact solutions the truncated system -- 8.2.4 The Liouville property -- 8.3 The statistical predictions for the truncated systems -- 8.4 Numerical evidence supporting the statistical prediction -- 8.5 The pseudo-energy and equilibrium statistical mechanics for fluctuations about the mean -- 8.6 The continuum limit -- 8.6.1 The case with a large-scale mean flow -- 8.6.2 The case without large-scale mean flow but with generic topography -- 8.6.3 The case with no geophysical effects -- 8.6.4 The case with no large-scale mean flow but with topography having degenerate spectrum -- High energy subcase -- 8.7 The role of statistically relevant and irrelevant conserved quantities -- References -- Appendix 1 -- 9 Empirical statistical theories for most probable states -- 9.1 Introduction -- 9.2 Empirical statistical theories with a few constraints -- 9.2.1 The energy-circulation empirical theory with a general prior distribution -- 9.2.2 The energy-circulation impulse theory with a general prior distribution -- 9.3 The mean field statistical theory for point vortices -- 9.3.1 Derivation of the mean field point-vortex theory from an empirical statistical theory -- 9.3.2 Complete statistical mechanics for point vortices -- The dynamics of point vortices in the plane -- Liouville property -- The mean field limit equations as N … -- 9.4 Empirical statistical theories with infinitely many constraints -- 9.4.1 Maximum entropy principle incorporating all generalized enstrophies -- 9.4.2 The most probable state and the mean field equation -- 9.5 Non-linear stability for the most probable mean fields -- References. , 10 Assessing the potential applicability of equilibrium statistical theories for geophysical flows: an overview.
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  • 2
    Publikationsdatum: 2018-05-15
    Beschreibung: Energies, Vol. 11, Pages 1242: Optimal Scheduling Strategies of Distributed Energy Storage Aggregator in Energy and Reserve Markets Considering Wind Power Uncertainties Energies doi: 10.3390/en11051242 Authors: Zengqiang Mi Yulong Jia Junjie Wang Xiaoming Zheng With continuous technological improvement and economic development of energy storage, distributed energy storage (DES) will be widely connected to the distribution network. If fragmented DES systems are aggregated to form a distributed energy storage aggregator (DESA), the DESA will have great potential to participate in the day-ahead energy and reserve market and the balancing market. The DESA could act as a mediator between the market and DES consumers, enabling beneficial coordination for DES owners and power systems. This paper presents a bilevel optimization model for DESAs in the energy and reserve market under wind power uncertainties. In the lower-level problem, generating companies, wind power plants (WPP), and DESAs are optimized for scheduling day-ahead (DA) energy and the reserve market. In the upper-level problem, operational strategies for DES systems and DESAs are designed to deal with wind power uncertainties in the balancing market. The DESA splits its resources between the energy and reserve markets so that it can reduce total power system consumption, and mutual profit for the system and end customers is achieved. This model is formulated as a mixed-integer linear programming (MILP) program, which can be solved with commercial software. The validity of the bilevel optimization model is verified by the eight-node test transmission system and IEEE-33 bus distribution system.
    Digitale ISSN: 1996-1073
    Thema: Energietechnik
    Publiziert von MDPI Publishing
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  • 3
    Publikationsdatum: 2014-07-14
    Beschreibung: This paper presents a hybrid model for early onset prediction of driver fatigue, which is the major reason of severe traffic accidents. The proposed method divides the prediction problem into three stages, that is, SVM-based model for predicting the early onset driver fatigue state, GA-based model for optimizing the parameters in the SVM, and PCA-based model for reducing the dimensionality of the complex features datasets. The model and algorithm are illustrated with driving experiment data and comparison results also show that the hybrid method can generally provide a better performance for driver fatigue state prediction.
    Print ISSN: 1024-123X
    Digitale ISSN: 1563-5147
    Thema: Mathematik , Technik allgemein
    Publiziert von Hindawi
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  • 4
    Publikationsdatum: 2018-03-09
    Beschreibung: IJGI, Vol. 7, Pages 85: Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers ISPRS International Journal of Geo-Information doi: 10.3390/ijgi7030085 Authors: Zhiyu Wang Zishen Li Liang Wang Xiaoming Wang Hong Yuan The real-time State Space Representation (SSR) product of the GNSS (Global Navigation Satellite System) orbit and clock is one of the most essential corrections for real-time precise point positioning (PPP). In this work, the performance of current SSR products from eight analysis centers were assessed by comparing it with the final product and the accuracy of real-time PPP. Numerical results showed that (1) the accuracies of the GPS SSR product were better than 8 cm for the satellite orbit and 0.3 ns for the satellite clock; (2) the accuracies of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) SSR product were better than 10 cm for orbit RMS (Root Mean Square) and 0.6 ns for clock STD (Standard Deviation); and (3) the accuracies of the BDS (BeiDou Navigation Satellite System) and Galileo SSR products from CLK93 were about 14.54 and 4.42 cm for the orbit RMS and 0.32 and 0.18 ns for the clock STD, respectively. The simulated kinematic PPP results obtained using the SSR products from CLK93 and CLK51 performed better than those using other SSR products; and the accuracy of PPP based on all products was better than 6 and 10 cm in the horizontal and vertical directions, respectively. The real-time kinematic PPP experiment carried out in Beijing, Tianjin, and Shijiazhuang, China indicated that the SSR product CLK93 from Centre National d’Etudes Spatiales (CNES) had a better performance than CAS01. Moreover, the PPP with GPS + BDS dual systems had a higher accuracy than those with only a GPS single system.
    Digitale ISSN: 2220-9964
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie
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  • 5
    Publikationsdatum: 2018-02-16
    Beschreibung: Energies, Vol. 11, Pages 438: Power-Balancing Based Induction Machine Model for Power System Dynamic Analysis in Electromechanical Timescale Energies doi: 10.3390/en11020438 Authors: Ding Wang Xiaoming Yuan Meiqing Zhang Power balance, including active and reactive power, between the system supply and the demand from induction motor loads is a potentially necessary condition for system stable operation. Motion of system states depends on the balancing of active and reactive powers. Therefore, this paper proposes an induction machine model in electromechanical timescale from a power balancing viewpoint, in which the induction motor load is modeled as a voltage vector driven by power balancing between the system supply and the demand from induction motor load, so as to describe the dynamic characteristics of induction motor loads in a physical way for power system dynamic analysis. Then a voltage magnitude-phase dynamic analysis with the proposed induction machine model is constructed. Based on the voltage magnitude-phase dynamic analysis, the characteristics of grid-connected induction motor loads are explored, and the instability mechanisms of grid-connected induction motor loads induced by a large disturbance are discussed. It is shown that the dynamic behavior of grid-connected induction motor loads can be described as the dynamic process of the terminal voltage vector driven by coupled active and reactive power balancing in different timescales. In this way, the dynamic behavior of induction motor loads in terms of voltage magnitude-phase dynamics and its physical characteristics are clearly illustrated. Time-domain simulation results are presented to validate the above analyses.
    Digitale ISSN: 1996-1073
    Thema: Energietechnik
    Publiziert von MDPI Publishing
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  • 6
    Publikationsdatum: 2017-11-08
    Beschreibung: Water, Vol. 9, Pages 865: Cyanobacterial Nitrogen Fixation Influences the Nitrogen Removal Efficiency in a Constructed Wetland Water doi: 10.3390/w9110865 Authors: Xiaodong Zhang Xin Jia Liang Yan Jinzhi Wang Xiaoming Kang Lijuan Cui Nitrogen removal efficiency in constructed wetlands (CW) is influenced by multiple environmental factors. However, little is known about the role of cyanobacterial nitrogen fixation in affecting nitrogen removal efficiency. This study investigated how cyanobacterial nitrogen fixation affects the efficiency, at which a CW removes nitrogen from an associated artificial lake (AL) in Beijing. For this purpose, we measured cell densities of N-fixing and non-N-fixing cyanobacteria, the aquatic nitrogen fixation rate (RNfix), and the concentration of various nitrogen fractions over the growing season (April–November) of 2014 in both AL and CW. We found that the removal of particulate organic nitrogen (PON) contributed to >90% of the total nitrogen removal in the CW. The removal efficiency of PON was lower during August–October (55.45 ± 27.49%) than during April–July (68.86 ± 8.83%). Phytoplankton proliferation in summer, as one of the main sources of PON, may have exceeded the capacity of the CW and led to declines in PON removal efficiency. RNfix peaked in July–October (3–169 ng N·L−1·h−1) and was positively correlated with both PON concentration and the cell density of N-fixing Anabaena sp. over the growing season, suggesting that aquatic nitrogen fixation (primarily in the AL) may increase PON and thereby reduce the its removal efficiency in the CW.
    Digitale ISSN: 2073-4441
    Thema: Energietechnik
    Publiziert von MDPI Publishing
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  • 7
    Publikationsdatum: 2018-05-02
    Beschreibung: Sensors, Vol. 18, Pages 1385: Geometric Integration of Hybrid Correspondences for RGB-D Unidirectional Tracking Sensors doi: 10.3390/s18051385 Authors: Shengjun Tang Wu Chen Weixi Wang Xiaoming Li Walid Darwish Wenbin Li Zhengdong Huang Han Hu Renzhong Guo Traditionally, visual-based RGB-D SLAM systems only use correspondences with valid depth values for camera tracking, thus ignoring the regions without 3D information. Due to the strict limitation on measurement distance and view angle, such systems adopt only short-range constraints which may introduce larger drift errors during long-distance unidirectional tracking. In this paper, we propose a novel geometric integration method that makes use of both 2D and 3D correspondences for RGB-D tracking. Our method handles the problem by exploring visual features both when depth information is available and when it is unknown. The system comprises two parts: coarse pose tracking with 3D correspondences, and geometric integration with hybrid correspondences. First, the coarse pose tracking generates the initial camera pose using 3D correspondences with frame-by-frame registration. The initial camera poses are then used as inputs for the geometric integration model, along with 3D correspondences, 2D-3D correspondences and 2D correspondences identified from frame pairs. The initial 3D location of the correspondence is determined in two ways, from depth image and by using the initial poses to triangulate. The model improves the camera poses and decreases drift error during long-distance RGB-D tracking iteratively. Experiments were conducted using data sequences collected by commercial Structure Sensors. The results verify that the geometric integration of hybrid correspondences effectively decreases the drift error and improves mapping accuracy. Furthermore, the model enables a comparative and synergistic use of datasets, including both 2D and 3D features.
    Digitale ISSN: 1424-8220
    Thema: Chemie und Pharmazie , Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von MDPI Publishing
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  • 8
    Publikationsdatum: 2015-04-01
    Beschreibung: The effectiveness of grouting scheme has been simulated to prevent the coal spontaneous combustion at a goaf in Haizi Colliery, China. The colliery has been operated for long period over 27 years and has a complex ventilation network including airflow leakages which could possibly lead to the spontaneous combustion of coal at goafs. Firstly, the mine ventilation simulator MIVENA was used to analyze the mine ventilation network airflows to control airflows in and out of working faces and goafs. As the second approach, numerical simulations were carried by the simulator FLUENT in order to predict spontaneous combustion of residual coal with leakage flow in the #3205 goaf. It was cleared that the goaf can be divided into three zones based on oxygen concentration in the goaf area. Finally, the numerical simulation results show that the slurry grouting method is able to be an effective and economical method by reducing porosity in the goaf area to prevent spontaneous combustion of residual coal.
    Print ISSN: 1687-8833
    Digitale ISSN: 1687-8841
    Thema: Geologie und Paläontologie
    Publiziert von Hindawi
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  • 9
    Publikationsdatum: 2016-12-31
    Beschreibung: Enterovirus 71 (EV71) usually causes hand-foot-and-mouth disease (HFMD) with severe clinical symptoms and even deaths in China. There is no efficient antiviral drug to protect against severe EV71-associated HFMD, making the development of EV71 vaccines therefore a priority. However, the potential target subject population(s) to be immunized with EV71 vaccine are not well understood. In this study, we characterized the epidemiology regarding EV71-associated HFMD on the basis of provincial-level surveillance. We extracted data on EV71-associated HFMD from the National Notifiable Disease Reporting System in Zhejiang Province, China between 1 January 2009 and 31 December 2013 (n = 7650). The higher incidence rate of EV71 cases occurred in those children aged 12–23 months, with boys being predominant. Interestingly, different peaks activities of EV71 infection was observed in different calendar year, with one peak in 2009 and 2013 and two peaks in 2010–2012. However, EV71 infection seemed to predominately occur in warm season and a distinguished cyclic peak that seemed to be of about 12 months. Children aged 12–23 months are thus identified as an important target population for public health intervention, for example, it is recommended that these key subjects immunized with EV71 vaccine. In addition, an enhanced surveillance system for EV71-associated with HFMD needs to focus on generic and phylogenetic analysis.
    Print ISSN: 1661-7827
    Digitale ISSN: 1660-4601
    Thema: Energietechnik , Medizin
    Publiziert von MDPI Publishing
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  • 10
    Publikationsdatum: 2017-01-22
    Beschreibung: To meet the great needs for MFL (magnetic flux leakage) inspection of drill pipes at wellheads, a lift-off-tolerant MFL testing method is proposed and investigated in this paper. Firstly, a Helmholtz coil magnetization method and the whole MFL testing scheme are proposed. Then, based on the magnetic field focusing effect of ferrite cores, a lift-off-tolerant MFL sensor is developed and tested. It shows high sensitivity at a lift-off distance of 5.0 mm. Further, the follow-up high repeatability MFL probing system is designed and manufactured, which was embedded with the developed sensors. It can track the swing movement of drill pipes and allow the pipe ends to pass smoothly. Finally, the developed system is employed in a drilling field for drill pipe inspection. Test results show that the proposed method can fulfill the requirements for drill pipe inspection at wellheads, which is of great importance in drill pipe safety.
    Digitale ISSN: 1424-8220
    Thema: Chemie und Pharmazie , Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von MDPI Publishing
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