Manganese in the shelf sediments off east coast of India

The distributional pattern of manganese in the shelf sediments off east coast of India has been determined. It is found that sediments from the immediate vicinity of river confluences, those of finer texture, and also those that are brownish in colour are generally more enriched in manganese. Manganese content decreases in a direction that is seaward from the coast and away from river confluences. An inverse relationship between the manganese content and the carbonate content of these sediments has been established, the richer the sediment in carbonate content the less the manganese concentration.     

Asymptotic behavior of terminating markov processes,near to ergodic

Several assertions are formulated regarding the asymptotic behavior of terminating Markov processes, near to ergodic.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 12, pp. 1701–1703, December, 1990.     

Near convexity,near smoothness and approximative compactness of half spaces in Banach spaces

The authors discuss the dual relation of nearly very convexity and property WS. By two kinds of near convexities and two kinds of near smoothness, the authors prove a series of characterizations such that every half-space in Banach space X and every weak* half-space in the dual space X* are approximatively weakly compact and approximatively compact. They show a sufficient condition such that a Banach space X is a Asplund space. Using upper semi-continuity of duality mapping, the authors also give two characterizations of property WS and property S.     

Compatible spreads of symmetry in near polygons

In De Bruyn [7] it was shown that spreads of symmetry of near polygons give rise to many other near polygons, the so-called glued near polygons. In the present paper we will study spreads of symmetry in product and glued near polygons. Spreads of symmetry in product near polygons do not lead to new glued near polygons. The study of spreads of symmetry in glued near polygons gives rise to the notion of ‘compatible spreads of symmetry'. We will classify all pairs of compatible spreads of symmetry for the known classes of dense near polygons. All these pairs of spreads can be used to construct new glued near polygons. Postdoctoral Fellow of the Research Foundation-Flanders.     

明渠层流失稳与沙纹成因机理研究

动床水流中,泥沙起动之后,往往要出现沙纹,沙纹成因各家的解释不一。白玉川,罗纪生的观点是:沙纹的尺度较小,主要是由于明渠层流不稳定性波或床面近壁流层中小尺度拟序结构发展演化所致。当床面边界附近扰动波或拟序结构以及水流自身所产生的床面底部切应力大于Shields切应力后,床面即产生响应,形成沙纹;如果扰动所产生的扰动切应力频率接近床面泥沙固有频率,则产生与泥沙颗粒的共振,这种现象也称之为“泥沙的检波性质”,此时床面发生最大响应,沙纹发展速度也最快。     

Solutions of the helmholtz equation, concentrated near a plane periodic boundary

The existence of solutions of the Helmholtz equation, exponentially decreasing with distance from a periodic boundary in the upper half-plane, is proved. These solutions exist for a special form of the boundary under the Dirichlet or Neumann boundary conditions. In either case, the boundary has the form of a chain of resonators joined with the upper half-plane by narrow splits. Bibliography: 7 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 250, 1998, pp. 83–96. Translated by V. Yu. Gotlib     

Geophysical investigations near the old workings for copper in Yanambail area,Khammam district,Andhra Pradesh

The old workings for copper, two miles north of Yanambail were first brought to light by Prof. C. Mahadevan, during his work in the Hyderabad Geological Survey 1941–43. Self potential, Resistivity and Magnetic methods of geophysical investigations were carried out by the authors near the old workings in an area of about 100 acres covering the entire old workings their strike continuation and in their neighbourhood. Negative centres were obtained near the old workings indicating the possible presence of richly concentrated copper ore body from about 30 feet depth. Another group of Negative centres of high magnitude were also found at a distance of about 500 feet towards East of old workings along a run of quartz vein. They are possibly due to the presence of another parallel mineralised vein.     

Near equality, near convexity, sums of maximally monotone operators, and averages of firmly nonexpansive mappings

We study nearly equal and nearly convex sets, ranges of maximally monotone operators, and ranges and fixed points of convex combinations of firmly nonexpansive mappings. The main result states that the range of an average of firmly nonexpansive mappings is nearly equal to the average of the ranges of the mappings. A striking application of this result yields that the average of asymptotically regular firmly nonexpansive mappings is also asymptotically regular. Throughout, examples are provided to illustrate the theory. We also obtain detailed information on the domain and range of the resolvent average.     

On algebras admitting a complete set of near weights,evaluation codes,and Goppa codes

In 1998 Høholdt, van Lint and Pellikaan introduced the concept of a “weight function” defined on a \({\mathbb{F}_q}\)-algebra and used it to construct linear codes, obtaining among them the algebraic geometry (AG) codes supported on one point. Later, in 1999, it was proved by Matsumoto that all codes produced using a weight function are actually AG codes supported on one point. Recently, “near weight functions” (a generalization of weight functions), also defined on a \({\mathbb{F}_q}\)-algebra, were introduced to study codes supported on two points. In this paper we show that an algebra admits a set of m near weight functions having a compatibility property, namely, the set is a “complete set”, if and only if it is the ring of regular functions of an affine geometrically irreducible algebraic curve defined over \({\mathbb{F}_q}\) whose points at infinity have a total of m rational branches. Then the codes produced using the near weight functions are exactly the AG codes supported on m points. A bound for the minimum distance of these codes is presented with examples which show that in some situations it compares better than the usual Goppa bound.     

Interaction of tide and surge in a semi-infinite uniform channel, with application to surge propagation down the east coast of Britain

The equations of motion for two plane progressive waves travelling together along a semi-infinite uniform channel are solved analytically. The effects of the various nonlinear terms are examined separately. The model is applied to the North Sea in an attempt to explain the observed magnitude of the interaction between tide and surge at different places on the east coast of Britain.     

The elementary diagram of a trivial,weakly minimal structure is near model complete

We prove that if M is any model of a trivial, weakly minimal theory, then the elementary diagram T(M) eliminates quantifiers down to Boolean combinations of certain existential formulas. M. C. Laskowski has been partially supported by NSF grant DMS-0600217.     

Hölder estimates near the boundary for generalized solutions of quasilinear,doubly degenerate,parabolic equations

One establishes Hölder estimates near the parabolic boundary of a cylinder Q_T for the generalized solutions of quasilinear, doubly degenerate, parabolic equations.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Institute im. V. A. Steklova Akademii Nauk SSSR, Vol. 188, pp. 45–69, 1991.     

Oscillations of a gas in an open-ended tube near resonance

The pressure as function of time was measured near resonance in different axial locations of an open-ended tube. Flow visualisation showed that transition to turbulence was not influenced by the strong disturbance of the open end, except in a region near the open end which had a length of about three particle displacements. The pressure readings were decomposed into the first, second and third harmonic and compared with two different theories. In one case, the linearized theory for the oscillating flow in a tube was fitted to the boundary conditions, the obvious one at the piston and a model at the open end. In the second case, the nonlinear theory of Chester [1] was used. Both theories assume a relation between pressure and velocity at the open end that contains two free constants. The constants were determined by comparing the amplitude of the first and the second harmonic ofone pressure measurement with the theoretical predictions. Once the constants are fixed, the pressurep(ωt, x/L) is completely determined. For weak nonlinear effects, the pressure is essentially determined by one constantα(=k ₂) and the second constantβ(=k ₁) loses its significance. For the range of parameters given there isα=0.825±0.015. A very good approximation of the pressure near resonance can therefore be calculated with the following simple boundary condition at the open end $$p_E = \frac{{4\alpha }}{{3\pi }}\rho \hat u_E u_E = 0.350 \rho \hat u_E u_E .$$ Both theories predict a resonance frequency slightly above the experimental one. Changing Levine and Schwingers [2], end correction from 0.6133R to 1R eliminates the discrepancy for all tube lengths. For the first harmonic the variation of the amplitude and the phase of the pressure signal withω andx is very well predicted by both theories. The nonlinear theory describes also the small second and third harmonics fairly well while the linear theory predicts only the correct order of magnitude of these higher harmonics. The constantα that determines the energy loss at the open end shows an apparent increase if the boundary layer on the tube wall becomes turbulent. This occurs for \(A = 2\hat u/\sqrt {v\omega } \geqq 550\) to 750 which is close to the value observed in a tube with a closed end.     

Second sound near lambda transition in presence of quantum vortices

In this paper, temperature waves (also known as second sound) are considered, with their respective coupling with waves in the order parameter describing the transition from normal phase to superfluid phase, and with waves in the vortex length density. We analyze the coupling between these three kinds of waves and explore its relevance in situations not far from the lambda transition. In particular, the expressions for the second sound speed and second sound attenuation are explicitly obtained within some approximations, showing the influence of the order parameter and the vortex length density, which is decisive close to the transition.

     

Solutions of nonlinear equations concentrated near curves in the plane

A method of successive approximations is considered which makes it possible to construct formal solutions of some nonlinear equations concentrated near curves in the plane.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 89, pp. 84–90, 1979.In conclusion, the author thanks V. M. Babich, A. Kachalov, and V. Nomofilov for fruitful discussions and valuable suggestions.     

On the dynamics near infinity of some polynomial mappings in

We construct the Green current for a random iteration of horizontal-like mappings in . This is applied to the study of a polynomial map with the following properties: i. infinity is f-attracting; ii. f contracts the line at infinity to a point not in the indeterminacy set. We study for such mappings the escape rates near infinity, i.e. the set of possible values of the function We show in particular that the set of possible values can contain an interval. On the other hand the Green current T of f can be decomposed into pieces associated to an itinerary defined by the indeterminacy points. This allows us to prove that exists ||T||-a.e. and we give its value in terms of explicit quantities depending on f.