Sheet Boundary Research Articles

Simulating Capillary Folding of Thin Elastic Sheets with Pinned Contact Lines

We consider the capillary folding of thin elastic sheets with pinned contact lines in three dimensions. The folding occurs due to the interaction between the elastic sheet and a droplet deposited on top of it. Firstly, we derive the equilibrium equations by minimizing the total energy of the system. This energy comprises the interfacial energies and the elastic energy, which is described by the nonlinear Koiter's model. Then we develop a time-splitting numerical scheme to solve the gradient flow dynamics. Following this dynamics, the system evolves towards the equilibrium state. At each time step, we first determine the droplet surface with a constant mean curvature by minimizing a squared area functional, subject to the boundary condition at the pinned contact line. The elastic sheet, discretized by the C1-conforming subdivision element method, is then evolved by taking into account the fluid pressure and the capillary force. We propose a novel remeshing strategy to avoid the need for interpolating the capillary force on the sheet boundary and to prevent simulations from breakdown due to distorted meshes. We perform numerical tests to demonstrate the accuracy of the numerical method, as well as its ability to predict folded structures for various types of sheets.

NURTURING TALENTS OF GEOMATICS SURVEYORS TO MEET THE CHALLENGES OF LAND SUPPLY, WORKS PROJECTS AND SMART CITY OF HONG KONG

Abstract. The challenges brought by a growing number of large-scale land development projects (e.g., Northern Metropolis, Lantau Tomorrow, and related infrastructures) in Hong Kong must be met by innovative land acquisition planning and processes. A recent quick win solution to land supply for Works projects has been in trial commissioning the provisional draft land resumption plan preparations and related survey works from the government to consultants, specifically the Authorized Land Surveyor (ALS) in the private sector. The industry therefore must consider the necessary and diverse sources of expertise available, and the existing land surveying technical resources that will render support to such new initiatives. Collaboration is called for between the spheres of public sector, education, and works industry to successfully move the use of cadastral survey for land management forwards, bridging the gap between lands and works practices for efficient processing of Works projects, and smart city development of Hong Kong.This paper will examine the new approach of professional surveying that private practicing ALSs bring, and why the overall number of ALS and engineering surveyors in the construction industry is growing so slowly. It will additionally compare Hong Kong's practice with that of the mainland China, Singapore, and the UK to grasp global learning points. The paper recommends the establishment of a Cadastral Survey Lab (CSL) firstly to explore the policy implementation of a sound cadastral system. The processing of lot boundary determination by ALS is reviewed. The regulatory roles of the Land Survey Authority (LSA) are requested in approving new land boundary plans; this both replaces the Demarcation District (DD) Sheet boundary and improves land boundary records. Secondly, the CSL can serve as a coordinating body in curating various kinds of land records from diverse sources, and aids the research and knowledge management of cadastral survey, land law, land tenure, land registration systems, land boundary record keeping, problematic lot boundary determination, etc. These topics can be considered in the refining geomatics education curriculum, and furthermore developed into guidance notes for geomatics survey practitioners.The evolution of the traditional land surveying profession into the geomatics services has become a recent international trend that is growing in popularity in the survey profession. Combining geo-spatial data from the planning and design stages, alongside the use of standardised survey data processing in project implementation and asset management, would encourage data sharing, avoid duplicate efforts, and facilitate the formation of a digital city. The spectrums of geomatics education in universities should be widened with a refined curriculum on combining geomatics with cadastral survey that has evolved from the traditional lot boundary survey to multi-purpose cadastre, city information modelling, urban informatics, smart city administration, and a full-blown Spatial Data Infrastructure (SDI).

Inhomogeneities of charge distribution in porous graphitic carbon nitride g-CxNy nanosheets

Porous graphitic carbon nitrides g-CxNy (g-CN, g-C2N and g-C3N4) were studied computationally using semi-empirical molecular orbital method to obtain insights into charge distribution in them. It is found that the charge distribution is inhomogeneous but has good symmetry in the symmetrical structure. And sheet boundary has significant effect on the charge distribution. All N atoms have negative charge due to electrons enrichment. The absolute charge value of the edge atoms is significantly larger than that of the internal atoms in g-CN and g-C2N, which is opposite in g-C3N4. For the C atom, all C atoms show positive charge in g-CN. However, in g-C2N, the double-bond and triple-bond C atoms at the boundary have different gain and loss electrons. The internal triple-bond C atoms show the same positive charge value.

Large-Scale Variations in Ion Flows in the Central Part and the Boundary of the Plasma Sheet

The results of multisatellite observations in a magnetotail at short distances ( $${\sim }10{{R}_{E}}$$ ) in two close regions inside the plasma sheet of the magnetotail and at the sheet boundary indicate the kinetic nature of processes in the magnetotail plasma. Disturbances simultaneously observed in ion flows and in their anisotropy occur due to the presence of a thin, kinetic current sheet in the tail. It is located at greater distances than the observation regions in such an experiment. It was shown earlier that the thin current sheet nested in the thicker plasma sheet is the most important component of the magneto-plasma structure, corresponding to the process of magnetic reconnection in the magnetotail. Therefore, the kinetic structures observed in such an experiment are manifestations of a typical disturbance that corresponds to magnetic reconnection at larger distances.

Classical spinning branes in curved backgrounds

The dynamics of a classical branelike object in a curved background is derived from the covariant stress-energy conservation of the brane matter. The world sheet equations and boundary conditions are obtained in the pole-dipole approximation, where nontrivial brane thickness gives rise to its intrinsic angular momentum. It is shown that intrinsic angular momentum couples to both, the background curvature and the brane orbital degrees of freedom. The whole procedure is manifestly covariant with respect to spacetime diffeomorphisms and world sheet reparametrizations. In addition, two extra gauge symmetries are discovered and utilized. The examples of the point particle and the string in 4 spacetime dimensions are analyzed in more detail. A particular attention is paid to the Nambu-Goto string with massive spinning particles attached to its ends.

Field‐aligned electrons at the lobe/plasma sheet boundary in the mid‐to‐distant magnetotail and their association with reconnection

We have surveyed field‐aligned electrons at the lobe/plasma sheet boundary and their association with reconnection in the distant magnetotail where reconnection is quasi‐steady and large scale. Asymmetric (in energy) counterstreaming electrons are detected in ∼30% of the boundary crossings when high‐speed flows are present in the plasma sheet. In 98% of the electron beam cases the low‐energy electrons are directed toward and the higher‐energy electrons directed away from the X‐line. The well‐organized (by the signs of Bx and Vx) quadrupolar pattern of the electrons indicates that these electrons are associated with reconnection. The low‐energy electrons could be the outer part of the Hall current loop, similar to previous reports in the near‐Earth region. The mean electron energy in the distant tail is a factor of ten lower than in the near‐Earth tail. Our observations suggest that the Hall effect can be detected even at large distances from the diffusion region.

Plasma sheet and magnetosheath plasma mixing in LLBL: Case study

Low latitude boundary layer (LLBL) of the magnetosphere of the Earth is formed due to the mixing of magnetosheath and plasma sheet plasma. The mixing process is studied on the base of Interball/Tail probe observations. The variations of the fluxes of ions (measured by CORALL instrument), electrons (measured by ELECTRON instrument) and particles with energies more than 25 keV (measured by DOK-2 instrument) are analyzed for the case of 21 September 1995 when the satellite intersects LLBL/plasma sheet boundary on the GSM (−4.1, −13.6, 2.2) R e distance. The variations of the magnetic field measured by MIF instrument are compared with the variations of particle fluxes. The thickness of the boundary region containing plasma from LLBL is estimated. The stress balance across the analyzed boundary is discussed. We find that the plasma pressure inside the LLBL is essential in understanding the pressure balance across the magnetopause.

合金化溶融亜鉛めっき鋼板の金属間化合物コーティング層のクラックと基材鋼の結晶粒界の関係

合金化溶融亜鉛めっき鋼板の金属間化合物コーティング層のクラックと基材鋼の結晶粒界の関係

Steady State of Dense Sheet Z-Pinch with Thermal Conduction

The problem of steady state of the sheet Z-pinch was solved, incorporating the thermal conductivity effects. In particular, solutions which incorporate low plasma pressure and low temperature on the sheet boundary are investigated. Three types of temperature profiles were identified. Dependence of the solution type on the pinch plasma parameters was determined.

In-Plane Diffusivity of Moisture in Paper

ABSTRACT Any nonuniformity in local moisture content of paper which develops during drying because of locally nonuniform drying rates provides a driving force for in-plane diffusion of moisture, which in turn acts to reduce this moisture nonuniformity. As no data have appeared for the in-plane diffusivity of moisture during desorption from paper over the range of conditions existing during papermachine drying, an investigation was undertaken to obtain this information. Moisture diffusivity was determined to he a very strong function of the extent and state of water in the sheet, increasing exponentially with paper moisture content. The presence or absence of liquid water at the sheet boundary would effect moisture difiusivity when there is water in the pores but the direction of moisture transport in paper was found to be of overriding importance. In-plane moisture diffusivity is very much greater than that in the thickness direction, indicating that the non-isotropic nature of paper structure is a key factor. A microscale view of the mechanism of moisture transport in the thickness and in-plane directions was developed, consistent with the enormous difference in effect of moisture content on diffusivity in the two directions.

Observations of a slow‐mode shock at the lobe‐plasma sheet boundary in Earth's distant magnetotail

A lobe‐plasma sheet boundary observed within Earth's distant magnetotail (XGSM ≃ −135 RE) with the Geotail spacecraft is interpreted in terms of a slow‐mode shock. Measurements of the three‐dimensional velocity distributions of protons and electrons and of the magnetic fields allow a quantitative comparison with theoretical predictions for a steady‐state, one‐dimensional shock. The observed plasma moments and magnetic field upstream from the shock are successfully used to predict these parameters in the downstream region. The measured parameters for this example of a lobe‐plasma sheet boundary are in sufficient agreement with the theoretical predictions to provide considerable confidence that this boundary is a slow‐mode shock.

Influence of a perpendicular magnetic field upon reconnection in a turbulent current sheet

The authors present results of an experimental study of the dependence of the current filament growth rate on the magnitude of the (perpendicular to the sheet) component of the magnetic field Bn. It is shown that in a turbulent current sheet the growth rate drops significantly when Bn>10-2Bb (Bb being the magnitude of the magnetic field on the sheet boundary), retaining then a constant value.

Evidence for slow‐mode shocks in the deep geomagnetic tail

Plasma and field data from the ISEE‐3 space probe provide evidence that the lobe‐plasma sheet boundary in the central part of the distant geomagnetic tail is often a slow‐mode shock. Such shocks are predicted by Petchek's model of reconnection. If this model applies, then the ISEE‐3 observations place the general location of the reconnection diffusion region closer to the earth than x ≈ −100 RE.

Distributed semiconductor R-C network analysis for various electrode configurations

The impedance of a semiconducting sheet of arbitrary boundary overlaid by a gate capacitance is analyzed as a function of frequency; the contacts are the gate contact and an ohmic contact at the sheet boundary. General asymptotic expressions for low and high frequency capacitance and for high frequency resistance are given. The low frequency equivalent series resistance is characterized by a form factor which depends on the configuration of the contact and can be determined experimentally from the frequencies at which equivalent circuit parameters extrapolated from the low and high frequency regimes intersect. The theoretical solution for the impedance pertaining to a rectangular boundary is given. The dependence of the impedance on the external a.c. circuit termination to a second gate contact is discussed for the case that the semiconducting sheet is bounded by distributed gate capacitances at both sides.

Satellite studies of magnetospheric substorms on August 15, 1968: 7. Ogo 5 energetic proton observations-spatial boundaries

Directional proton fluxes (0.1–0.8 Mev) observed at pitch angles near 90° to B during the growth phase of the 0714 UT August 15, 1968, substorm showed a strong east-west asymmetry. Since the Ogo 5 spacecraft was in the north edge of the midnight plasma sheet in a taillike magnetic field, the Lawrence Livermore Laboratory (LLL) spectrometer observed westward-directed fluxes having their gyrocenters located south of the satellite deeper in the sheet and eastward-directed fluxes having their gyrocenters north of the satellite toward the sheet boundary. We have used the directional flux variation to determine the flux profile north to south of Ogo 5 over ∼±0.4 RE approximately every 2 min during the substorm growth phase, 0640–0714 UT. At 0610 UT, before the substorm, the e fold length of the flux gradient was ∼1.3 RE, which slowly changed to ∼1.0 RE at 0640 UT, the start of the substorm growth phase. A thinning wave developed north of Ogo 5, showing an e fold length of ∼0.1 RE at 0700 UT, which dropped to ∼0.03 RE as the thinning wave passed south of the orbit of Ogo 5 just before the onset of expansion. The data suggest that the plasma sheet at ∼8 RE had shrunk from a half-thickness of >1.5 RE before the substorm to a few tenths of an earth radius. The velocity of the thinning wave perpendicular to B was found to vary from ∼4 km/sec at 0655 UT early in the growth phase to a peak of ∼10 km/sec just before expansion. The velocity of outward expansion of the plasma sheet in a direction inclined ∼45° to the GSM equator was estimated as 90 ± 30 km/sec.