Technical foundation research on high resolution remote sensing system of China''s coastal zone

China‘s coastal zone is a region with a highly developed economy that contrasts clearly with the slow paced regular investigation on its natural environment, which cannot keep pace with the requirement of economic development and modem management.Laying a theoretical foundation for the modem management of China‘s costal zone is aimed at.This research focuses on the following processing and analyzing technologies for coastal zone high-resolution remote sensing data: organization and management of large amounts of high-resolution remote sensing data, quick and precise spatial positioning system,algorithms for image fusion in feature level and coastal zone feature extraction. They will form a technical foundation of the system. And, if combined with other research results such as coastal zone remote sensing classification system and its mapping subsystem, an advanced technical frame for remote sensing investigation of coastal zone resource will be constructed.     

Not In The Same World: Topological Youths,Topographical Policies

Public attitudes continue to portray youths in Western societies as being passive and disengaged. Critical scholars are largely unanimous in that the misrecognition of and disrespect for young people's everyday experiences and activities form a major reason why they appear detached from politics and public life. Contributing to this debate, this paper traces the everyday experiences of some Finnish urban youths, and argues that their lived worlds differ notably from the worlds of the public administration that seeks to address youths as active citizens. Based on these findings, the paper proposes the pragmatically oriented concepts of “issue publics” and “topological connectives” for rethinking youth participation and democratic life more broadly.     

Displacement ring load Green's functions for saturated porous transversely isotropic tri‐material full‐space

Based on the Biot's poroelastic theory and using scalar potential functions both the ring load and point load displacement Green's functions for a transversely isotropic saturated porous full‐space composed of an upper half‐space, a finite thickness middle layer and a lower half‐space is analytically presented for the first time. It is assumed that each region consists of a different transversely isotropic material. The equations of poroelastodymanics in terms of the solid displacements and the pore fluid pressure are uncoupled with the help of two scalar potential functions, so that the governing equations for the potential functions are either a second order wave equation or a repeated wave‐heat transfer equation of sixth order. With the aid of Fourier expansion with respect to circumferential direction and Hankel integral transforms with respect to the radial direction in cylindrical coordinate system, the response is determined in the form of line integrals in the real space, followed by theorem of inverse Hankel integral transforms. The solutions degenerate to a single phase elastic material, and the results are compared with previous studies, where an excellent agreement may be observed with the results provided in the literature. Some examples of displacement Green's functions are finally given to illustrate the solution. Copyright © 2016 John Wiley & Sons, Ltd.     

Assessment of rainfall spatial variability and its influence on runoff modelling: A case study in the Brue catchment,UK

This study explores rainfall spatial variability and its influence on runoff modelling. A novel assessment scheme integrated with coefficient of variance and Moran's I is introduced to describe effective rainfall spatial variability. Coefficient of variance is widely accepted to identify rainfall variability through rainfall intensity, whereas Moran's I reflects rainfall spatial autocorrelation. This new assessment framework combines these two indicators to assess the spatial variability derived from both rainfall intensity and distribution, which are crucial in determining the time and magnitude of runoff generation. Four model structures embedded in the Variable Infiltration Capacity model are adopted for hydrological modelling in the Brue catchment of England. The models are assigned with 1, 3, 8, and 27 hydrological response units, respectively, and diverse rainfall spatial information for 236 events are extracted from 1995. This study investigates the model performance of different partitioning based on rainfall spatial variability through peak volume (Q_p) and time to peak (T_p), along with the rainfall event process. The results show that models associated with dense spatial partitioning are broadly capable of capturing more spatial information with better performance. It is unnecessary to utilize models with high spatial density for simple rainfall events, though they show distinct advantages on complex events. With additional spatial information, Q_p experiences a notable improvement over T_p. Moreover, seasonal patterns signified by the assessment scheme imply the feasibility of seasonal models.     

A simplified analysis method for piled raft foundations subjected to ground movements induced by tunnelling

A simplified method of numerical analysis has been developed to estimate the deformation and load distribution of piled raft foundations subjected to ground movements induced by tunnelling and incorporated into a computer program ‘PRAB’. In this method, a hybrid model is employed in which the flexible raft is modelled as thin plates, the piles as elastic beams, and the soil is treated as interactive springs. The interactions between structural members, pile–soil–pile, pile–soil–raft and raft–soil–raft interactions, are modelled based on Mindlin's solutions for both vertical and lateral forces. The validity of the proposed method is verified through comparisons with some published solutions for single piles and pile groups subjected to ground movements induced by tunnelling. Thereafter, the solutions from this approach for the analysis of a pile group and a piled raft subjected to ground movements induced by tunnelling are compared with those from three‐dimensional finite difference program. Good agreements between these solutions are demonstrated. The method is then used for a parametric study of single piles, pile groups and piled rafts subjected to ground movements induced by tunnelling. Copyright © 2005 John Wiley & Sons, Ltd.     

Solute Sources and Processes in the Achankovil River Basin,Western Ghats,Southern India/Sources de Solutés et Processus Associés Dans le Bassin du Fleuve Achankovil,Ghats Occidentaux,Inde du Sud

Abstract

A time series survey was carried out in 2002 to understand the hydrogeochemical processes taking place in the Achankovil River of the Western Ghats Range. The water is neutral with pH and EC ranges from 6.32 to 7.56 and 24–54 µS cm^?1, respectively. Chloride and sodium are the dominant anion and cation in the water respectively. Correlation analysis of the chemical parameters of the water shows that few ions have additional sources. The majority of carbonate is derived from carbonate weathering followed by silicate weathering. Cation concentrations show decreasing trend from upstream to downstream in contrast to the increasing trend in the major world rivers. Dissolved silica in pre-monsoon water is low. The river chemistry is dominated by rock weathering induced by precipitation. Thermodynamic plots show that dolomite, kaolinite, albite and chlorite are in equilibrium with the river water. Chemical weathering is predominant here compared to physical weathering. The overall material transport seems to be lower compared to the other Indian rivers; nevertheless, the solute loads are comparable to certain large rivers such as the River Cauvery in southern India. The solute flux including the nutrient flux is very high among the Western Ghats rivers in relation to its size, which will certainly supplement the productivity of the lake/estuary and the coastal waters. Since this study is restricted to a one-year period, long-term data procurement and analysis along with micro nutrients studies are needed, which are lacking in the present study, to gain insight into the material flux by this river into the Arabian Sea.     

Three‐dimensional time‐harmonic fundamental solutions for a fluid‐saturated poroelastic half‐space with partially permeable free surface

By virtue of a pair of scalar potentials for the displacement of the solid skeleton and the pore fluid pressure field of a saturated poroelastic medium, an alternative solution method to the Helmholtz decomposition is developed for the wave propagation problems in the framework of Biot's theory. As an application, a comprehensive solution for three‐dimensional response of an isotropic poroelastic half‐space with a partially permeable hydraulic free surface under an arbitrarily distributed time‐harmonic internal force field and fluid sources is developed. The Green's functions for the poroelastic fields, corresponding to point, ring, and disk loads, are reduced to semi‐infinite complex‐valued integrals that can be evaluated numerically by an appropriate quadrature scheme. Analytical and numerical comparisons are made with existing elastic and poroelastic solutions to illustrate the quality and features of the solution. Copyright © 2016 John Wiley & Sons, Ltd.     

Diachronous Palaeoproterozoic deformation and metamorphism in the Committee Bay belt,Rae Province,Nunavut: insights from 40Ar–39Ar cooling ages and thermal modelling

Regional‐scale ⁴⁰Ar–³⁹Ar data presented in this paper reveal significant across‐strike and along‐strike age differences in the Committee Bay belt (CBb), Rae Province, Nunavut, Canada, that complement variations in observed monazite ages. ⁴⁰Ar–³⁹Ar hornblende ages are c. 1795, 1775, and 1750 Ma in the western, eastern and central parts of the Prince Albert Group (PAG) domain respectively. The migmatite domain and Walker Lake intrusive complex are characterized by c. 1750–1730 ⁴⁰Ar–³⁹Ar hornblende ages without significant along‐strike variation. The ⁴⁰Ar–³⁹Ar data provide important constraints on the cooling history and on thermal modelling that elucidates the controls on diachroneity and metamorphic patterns within the belt. In the western CBb, prograde monazite growth occurred 26 ± 10 Myr earlier in the migmatite domain (1864 ± 9 Ma; peak P–T = 5 kbar?700 °C) than in the PAG domain (1838 ± 5 Ma; peak P–T = 5 kbar?580 °C). Calculations indicate that this earlier monazite growth results from tectonic thickening of higher heat productivity Archean lithologies in the migmatite domain, which undergoes more rapid prograde heating than the less radiogenetic and lower grade rocks of the PAG domain. Granite generation via biotite dehydration melting at 800 °C and 20 km depth is predicted to occur c. 1835 Ma, in agreement with geochronological constraints. The tectonic burial of crustal domains with contrasting radiogenic properties also explains the general congruence of lower to upper amphibolite facies metamorphic zones generated during the two main orogenic cycles (i.e. M₂–D₁ and M₃–D₂). The modelled timing of prograde monazite growth in the migmatite domain suggests that D₂ tectonic thickening began at 1872 ± 9 Ma, some 8 ± 3 Myr before monzazite growth, coeval with the inferred time of collision of the Meta Incognita terrane with the southern Rae Province. Along‐strike diachroneity, reflected in 25 Myr younger monazite and ⁴⁰Ar–³⁹Ar hornblende ages in the eastern relative to the western PAG domain, cannot be accounted for by heat productivity contrasts along the belt. Instead the younger deformation and metamorphism in the eastern CBb was driven by its proximity to the eastern promontory of the Superior Province which collided with the Rae Province at c. 1820 Ma. The ⁴⁰Ar–³⁹Ar data presented here support the interpretation that the youngest monazite in the CBb crystallized at c. 1790 Ma in the central CBb when this part of the belt was downfolded into a gentle synformal structure while the western part of the belt cooled through ⁴⁰Ar–³⁹Ar hornblende closure. The results of this study illustrate the important influence of contrasting rock properties on the thermal evolution of orogenic belts and on the temporal record of this evolution.     

The destabilising nature of differential rotation

Abstract

In a rapidly rotating, electrically conducting fluid we investigate the thermal stability of the fluid in the presence of an imposed toroidal magnetic field and an imposed toroidal differential rotation. We choose a magnetic field profile that is stable. The familiar role of differential rotation is a stabilising one. We wish to examine the less well known destabilising effect that it can have. In a plane layer model (for which we are restricted to Roberts number q = 0) with differential rotation, U = sΩ(z)1 _?, no choice of Ω(z) led to a destabilising effect. However, in a cylindrical geometry (for which our model permits all values of q) we found that differential rotations U = sΩ(s)1 _? which include a substantial proportion of negative gradient (dΩ/ds ≤ 0) give a destabilising effect which is largest when the magnetic Reynolds number R _m = O(10); the critical Rayleigh number, Ra _c, is about 7% smaller at minimum than at R_m = 0 for q = 10⁶. We also find that as q is reduced, the destabilising effect is diminished and at q = 10^?6, which may be more appropriate to the Earth's core, the effect causes a dip in the critical Rayleigh number of only about 0.001%. This suggests that we see no dip in the plane layer results because of the q = 0 condition. In the above results, the Elsasser number A = 1 but the effect of differential rotation is also dependent on A. Earlier work has shown a smooth transition from thermal to differential rotation driven instability at high A [A = O(100)]. We find, at intermediate A [A = O(10)], a dip in the Ra_c vs. R_m curve similar to the A = 1 case. However, it has Ra_c ≤ 0 at its minimum and unlike the results for high A, larger values of R_m result in a restabilisation.     

Magnetic Rossby waves in a stably stratified layer near the surface of the Earth's outer core

Abstract

The stratification profile of the Earth's magnetofluid outer core is unknown, but there have been suggestions that its upper part may be stably stratified. Braginsky (1984) suggested that the magnetic analog of Rossby (planetary) waves in this stable layer (the ‘H’ layer) may be responsible for a portion of the short-period secular variation. In this study, we adopt a thin shell model to examine the dynamics of the H layer. The stable stratification justifies the thin-layer approximations, which greatly simplify the analysis. The governing equations are then the Laplace's tidal equations modified by the Lorentz force terms, and the magnetic induction equation. We linearize the Lorentz force in the Laplace's tidal equations and the advection term in the magnetic induction equation, assuming a zeroth order dipole field as representative of the magnetic field near the insulating core-mantle boundary. An analytical β-plane solution shows that a magnetic field can release the equatorial trapping that non-magnetic Rossby waves exhibit. A numerical solution to the full spherical equations confirms that a sufficiently strong magnetic field can break the equatorial waveguide. Both solutions are highly dissipative, which is a consequence of our necessary neglect of the induction term in comparison with the advection and diffusion terms in the magnetic induction equation in the thin-layer limit. However, were one to relax the thin-layer approximations and allow a radial dependence of the solutions, one would find magnetic Rossby waves less damped (through the inclusion of the induction term). For the magnetic field strength appropriate for the H layer, the real parts of the eigenfrequencies do not change appreciably from their non-magnetic values. We estimate a phase velocity of the lowest modes that is rather rapid compared with the core fluid speed typically presumed from the secular variation.