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In this commentary on Steven H. Cooper’s paper, the author acknowledges that the term boundary violation presents a vexing problem when we try to integrate it with the traditional use of the term boundary in psychoanalytic thought. He suggests that the two discourses represent two separate but somewhat related levels of discourse and that overlap occurs in some areas but not in others. While the use of “boundary violations” to describe ethical misconduct presents problems, the author suggests that it may be useful for some analysts who have experienced a collapse of analytic space and can no longer “play” in a symbolic realm. He also suggests that we may be stuck with the term because of the unconscious function it serves for the analytic community.

An electromagnetic or acoustic beam incident on a randomly rough boundary is modelled as a random phase screen. The particular case of a gaussian beam incident on a screen whose phase is a gaussian process is considered in detail. The technique, which uses Papoulis' extension of Woodward's ambiguity function for random fields, is finally applied to arbitrary transmitting and receiving antennas (or transducers) coupled through a phase screen whose statistics are arbitary but stationary

This paper considers the local stability problem and estimates the region of attraction (RA) of the positive equilibrium of Lotka-Volterra (L-V) competitive system with time-delays. Based on the stability theory and the quadratic system theory, by choosing some less conservative integral inequalities and appropriate Lyapunov-Krasovskii (L-K) functional, a local stability condition is obtained by means of linear matrix inequalities (LMI) and the estimate of RA of the positive equilibrium is first discussed. Furthermore, the corresponding optimization problem for the estimate of RA is given. Numerical simulations show that the proposed stability condition in this paper is less conservative as compared with the most existing ones and the method of estimating RA is effective.

This paper sets out to better understand the role of ethnic boundary dynamics in immigrant entrepreneurship, in particular in terms of intersections at the boundaries between ‘ethnic’ and ‘mainstream’ economies, internal differentiation within ethnic community boundaries, and the socially constructed nature of ethnic boundaries more broadly. To better account for these dynamics, we develop a Barthian perspective on immigrant entrepreneurship, building on and integrating Fredrik Barth’s work on entrepreneurship, ethnic boundaries, and spheres of value. A Barthian perspective shifts the analytic focus from the ethnic group to entrepreneurial activities and, by implication, to the ethnic boundary dynamics that these activities generate. We draw on ethnographic research conducted among immigrant Mennonite entrepreneurs in Belize, and identify three boundary dynamics among the Mennonites: bridging the boundary between Mennonite ethnicity and the wider Belizean society, stretching the boundaries of individual Mennonite communities, and allying across the boundaries between Mennonite communities. In developing a Barthian perspective, the contribution of our paper lies in developing a comprehensive framework for understanding the role of ethnic boundary dynamics in immigrant entrepreneurship, thereby also responding to calls for more micro-processual approaches to understanding the ‘mixed embeddedness’ of immigrant entrepreneurs in their ethnic community and the wider society contexts.

The aim of the present paper is to developed analytical elasticity solution for a beam having longitudinal stiffness variation using recently developed multiterm extended Kantorovich (EKM) method. By applying the EKM method, the system of 4n first order ordinary differential equations (ODEs) and 1n algebraic equation are obtained along the in-plane (x) and thickness (z) directions. The system of the equations along the thickness direction (z) having constant coefficient but the set of equations along the x-direction have variable coefficients. In the thickness direction (z), exact closed-form solutions are obtained. And along the x-direction, the system of ODEs with variable coefficients are solved by employing the modified power series. In this paper, specific predefined variations are assumed in material property and their influence on the bending response of beam, subjected to mechanical loading, is investigated. Benchmark numerical results are presented for a different combination of boundary ...

In this paper we define and study the billiard problem on bounded regions on surfaces of constant curvature. We show that this problem defines a 2-dimensional conservative and reversible dynamical system, defined by a Twist diffeomorphism, if the boundary of the region is an oval. Using these properties and defining good perturbations for billiards, we show, in this new version, that having only a finite number of nondegenerate periodic orbits for each fixed period is an open property for billiards on surfaces of constant curvature and a dense one on the Euclidean and the hyperbolic planes. For the proof of the density, the techniques we use for the Euclidean and hyperbolic cases, do not work for the spherical case, due to a constraint (the perimeter of the polygonal trajectory being a multiple of {\pi}). We finish this paper studying the stability of these nondegenerate orbits., Comment: 11 pages, no figures

This paper presents a granular computing approach to spatial classification and prediction of land cover classes using rough set variable precision methods. In particular, it presents an approach to characterizing large spatially clustered data sets to discover knowledge in multi-source supervised classification. The evidential structure of spatial classification is founded on the notions of equivalence relations of rough set theory. It allows expressing spatial concepts in terms of approximation space wherein a decision class can be approximated through the partition of boundary regions. The paper also identifies how approximate reasoning can be introduced by using variable precision rough sets in the context of land cover characterization. The rough set theory is applied to demonstrate an empirical application and the predictive performance is compared with popular baseline machine learning algorithms. A comparison shows that the predictive performance of the rough set rule induction is slightly...

This paper proposes a mathematical method to solve the equilibrium equations of a membrane with rigid and cable boundaries for the so-called prestressing phase. More exactly, no constrained thrust network approach is implemented and the problem is studied starting directly from its continuous formulation. In this sense, the membrane is represented by a regular surface with negative Gaussian curvature, and its boundary by a set of regular curves, whose curvature depends on the structural elements, rigid or cable. The equilibrium is expressed by means of boundary differential problems in terms of the membrane shape and its stress tensor. The membrane-cable interface equilibrium requires taking into account a singular condition which makes the problem more complex. Therefore, the corresponding mathematical problem is defined and analysed, and its principal qualitative aspects are discussed in this paper. Moreover, a numerical resolution procedure is proposed and applied.

The natural element method (NEM) is a special meshless method. Its shape functions are constructed using natural neighbor node interpolations based on the concepts of Voronoi tessellation. The NEM interpolation is linear between adjacent nodes on the boundary of the convex hull, which facilitates imposition of essential boundary conditions. However, for a three-dimensional problem, the computation of shape function derivative of NEM is still very complicated even with the non-Sibson interpolation function, which makes the NEM an unpopular numerical method. In this paper, we adopt the direct mathematical derivative technique, and after some rigorous deduction, finally obtain the shape function derivative expression of three-dimensional NEM. Compared with the Lasserre algorithm, this algorithm is more intuitionistic and can be conveniently programmed. The NEM numerical results for cantilever beams verify the correctness of the shape function derivative expression of NEM derived in this paper.

The boundary knot method (BKM) is an inherent boundary-type meshless collocation method for partial differential equations (PDEs). Using non-singular general solutions, numerical solutions of the PDE can be obtained based on the boundary points. In this paper, we investigate the applications of the BKM to solve Helmholtz problems involving various boundary conditions. We use the effective condition number to investigate the ill-conditioned interpolation system. Different from previous investigations, numerical results in this paper reveal that the BKM is promising in dealing with Helmholtz problems under only partially accessible boundary conditions.

In this paper, exponential finite-time coordination problems of multi-agent systems are investigated, including containment control and consensus. The theoretical basis is that a class of nonlinear systems has favourable finite-time convergence characteristic. For the objective of containment control, the proposed protocol ensures that the boundary agents in the same strong component exponentially reach a consensus and the internal agents exponentially converge to the convex hull spanned by the boundary agents in a finite time. For the objective of consensus, a pinning control strategy is designed for a fraction of agents such that all the agents exponentially reach a consensus with the leader in a finite time. The distinguished features of this paper lie in the following two points: (1) a smaller settling time of the Lyapunov function is obtained, which manifests in a faster convergence rate than the traditional one and (2) the weakly connected topology considered in this paper is more general than the o...

Multiscale modelling has great advantages by simulating material behaviours on one level using information from another level. The popular multiscale methodology couples the atomistic/meso particle model with the continuum model (e.g., multiscale model by coupling molecular dynamics and finite element analysis). In this paper, a new multiscale method is proposed using the numerical manifold method (NMM) and its micro extension particle manifold method (PMM). Due to the same mathematical and mechanical scheme NMM and PMM adopt, their multiscale coupling has a uniform framework and does not need special treatment at the multiscale boundary. The proposed method has an advantage over PMM in presenting the material’s micro structure and failure description. It also saves the computational resource by using NMM to present the macro part. In the paper, the multiscale methodology is presented with some numerical demonstrations. It is proven that this novel multiscale manifold method is a good tool for analysis of...

This paper presents a mathematical problem related to the equilibrium analysis of a membrane with rigid and cable boundaries for the so-called prestressing phase. The idea of using membranes in civil engineering applications such as footbridges, a new technology being developed in Spain, implies higher structural responsibility and more accurate analysis procedures. The membrane is represented by a regular surface with negative gaussian curvature, and its boundary by a set of regular curves the curvature of which depends on the structural elements, rigid or cable. Equilibrium is directly expressed by means of boundary differential problems in terms of the membrane shape and its stress tensor. The membrane–cable interface equilibrium requires taking into account a singular condition that makes the problem more difficult. Therefore, starting from the equilibrium equations, two mathematical approaches can be considered: a direct problem and a dual problem. The direct problem is defined and analysed, and its principal qualitative aspects are studied in this paper. Moreover, a numerical solution procedure is proposed to obtain practical results.

This paper presents a review of recent research investigations on the computer modelling of flexible bodies in railroad vehicle systems. The paper will also discuss the influence of the structural flexibility of various components, including the wheelset, the truck frames, tracks, pantograph/catenary systems, and car bodies, on the dynamics of railroad vehicles. While several formulations and computer techniques for modelling structural flexibility are discussed in this paper, a special attention is paid to the floating frame of reference formulation which is widely used and leads to reduced-order finite-element models for flexible bodies by employing component modes synthesis techniques. Other formulations and numerical methods such as semi-analytical approaches, absolute nodal coordinate formulation, finite-segment method, boundary elements method, and discrete elements method are also discussed. This investigation is motivated by the fact that the structural flexibility can have a significant effect on...

In this paper, we consider the exponential stabilisation problem of a Timoshenko beam with delay in boundary control. Suppose that the controller outputs of the forms α1u1(t) + β1u1(t − τ) and α2u2(t) + β2u2(t − τ) where u1(t) and u2(t) are the inputs of boundary controllers. In the past, most of the stabilisation results are required αj > βj > 0, j = 1, 2. In the present paper, we shall give a new dynamic feedback control law that makes the system exponential stabilisation ∀τ > 0 provided that |αj| ≠ |βj|(j = 1, 2). The exponential stabilisation result is proved via test of exact observability of the system.

This paper applies the boundary face method (BFM) to solve both steady-state and unsteady-state heat conduction problems in the dam construction. Instead of employing the isoparametric elements as in the boundary and finite element methods, the BFM uses directly geometric models from CAD packages to avoid geometric errors for any complex structures. Moreover, the variable approximations and the boundary integration are all performed in the parametric space of the boundary surfaces, which means that the elements and integral patches are defined in the parametric space. A numerical example of steady-state analysis presented in this paper is a concrete dam structure which consists of several blocks. The example of unsteady-state analysis, which concerns a single block with several holes in it, has also been presented to illustrate the validity and the efficiency of the proposed method.

title/>This paper presents an algorithm of buffer construction incorporating run-length encoding and the idea of raster overlay method. In traditional raster methods, the buffer target is traced and scanned using a ‘brush’, the width of which is equal to the buffer distance. During this process, the brushed raster grids are marked. Then by carrying out dynamic calculation on these marked grids, the buffer zone, constituted of grids, would be generated. Finally, the desired boundary of the buffer zone could be obtained through vectorisation. Considering the obvious drawbacks of raster data in computing efficiency and storage capacity, this paper puts forward the idea of storing raster data by means of run-length encoding, on which the raster-based operations are carried out. In order to improve the spatial precision, the borderlines of each run-length unit are recorded in the data of real type. The tests and analyses indicate that this algorithm has integrated advantages with respect to time comple...

One of the problems in detecting occlusions when generating true ortho photos is false occlusion and false visibility caused by rolling terrain, and the resolution difference between the digital surface model (DSM) and the images. Published methods are plagued by unstable computation and have considerable noise. The paper presents a vector-based backward projection (VBP) method for detecting occlusions. First, the method projects vector polygons representing the surface of buildings to image space. Next, it derives their true coverage by judging the occupancy priority for the overlap. It then determines the visibility of building and digital elevation model (DEM) grids. Finally, it generates a true ortho image by differential rectification. In addition, this paper develops methods to keep all steps robust, such as dubious region growing methods for rasterization and judgment formulas for boundary noise elimination, which makes VBP practical. Experiments using the Z-Buffer method, the projection-ray-angle-...

A technique for numerical analysis of the dynamics of the ring-spinning balloon based on radial basis function networks (RBFNs) is presented in this paper. This method uses a ‘universal approximator’ based on neural network methodology to solve the differential governing equations which are derived from the conditions of the dynamic equilibrium of the yarn to determine the shape of the yarn balloon. The method needs only a coarse finite number of collocation points without any finite element-type discretisation of the domain and its boundary for numerical solution of the governing differential equations. This paper will report a first assessment of the validity and efficiency of the present mesh-less method in predicting the balloon shape across a wide range of spinning conditions.

We consider open, discrete mappings between domains from R n satisfying condition (N), having local ACL n inverses on D∖B f , so that μ n (B f ) = 0, H*(·, f) < ∞ on B f and . For this class of mappings (or even for larger classes of open, discrete mappings) we generalize the important modular inequality of Poleckii, also using the modular estimates of the spherical rings from Cristea (Local homeomorphism having local ACL n inverses, Complex Var. Elliptic Equ. 53(1) (2008), 77–99). We continue the work from the same paper by generalizing some basic facts from the theory of quasiregular mappings. We give equicontinuity results, Picard, Montel and Liouville type theorems, estimates of the modulus of continuity, analogues of Schwarz's lemma, eliminability results and boundary extensions theorems. Together with the multiple extensions of Zoric's theorem from the paper, we establish strong generalizations of one of the most important theorems from the theory of quasiregular mappings. We also extend similar res...

In close-range photogrammetry, 3D information acquisition is based on image matching. The application of code marker helps to improve the level of automatic matching and the matching accuracy. This paper investigates the application of inertia ellipse algorithm to code marker matching. We can calculate the inertia ellipse of a target with a certain boundary. First, the method is applied to a single code marker; the angle and scaling are valid. Then, the paper introduces the multi code markers matching method by the inertia ellipse. Rotation and scaling changes of homonymy images can be calculated by inertia ellipse algorithm. These parameters can be used for code marker matching in arbitrary attitude close-range photogrammetry.

Cadastral modelling uses the cadastral data including bearings and distances of boundary lines to calculate coordinates of boundary corners and associated marks, and to evaluate the data. This paper shows that at sites where several boundary corners are intended to be on a straight line a Least Squares adjustment of the boundary data may cause the points to move away from one straight line. Methods of constraining boundary corners to stay on straight lines, when that is desired, in a Least Squares solution of cadastral boundary data are described in this paper. The LS process and equations are given for constraining points to stay on a straight line by using fixed 180° angle observations or by using parameter constraint equations. Also, considered are multiple points on a line, parallel line constraints and constraints to keep boundary points on a circular arc, where appropriate. An example is given to demonstrate the application and effect of the constraints.

A powerful approach for dynamic optimization in the presence of uncertainty is to incorporate measurements into the optimization framework so as to track the optimum. For nonsingular control problems, this can be done by tracking active constraints along boundary arcs and using neighboring- extremal (NE) control along interior arcs. Essentially, NE control forces the first-order variation of the necessary conditions of optimality (NCO) to zero. In this paper, an extension of NE control to singular control problems is proposed. The paper focusses on single-input systems, while the extension to multiple-input systems is investigated in the companion paper. The idea is to design NE controllers from successive time differentiations of the first- order variation of the NCO. ApproximateNE-feedbacklaws arealsoproposed, which are both easily implementable and tractable from a real-time optimization perspective. These developments are illustrated by the case study of a semi-batch chemical reactor.

This article considers the periodic review stochastic inventory models with service level constraint to provide an improved solution procedure. The previous researchers assumed that the objective function is concave down in the lead time so that the minimum must occur on the boundary points of each sub-domain. In this article, we will show that their assumption is questionable since the minimum might not occur at the boundary points of each sub-domain. In a recent paper in International Journal of Systems Science, Ouyang and Chuang studied this problem. However, their solutions contained questionable results and their algorithm might not find the optimal solution due to flaws in their solution procedure. We develop some lemmas to reveal the parameter effects and then present our improved solution procedures for finding the optimal solution for periodic review stochastic inventory models in which the lead time demand is a normal distribution. The savings are illustrated by solving the same examples from Ouyang and Chuang's paper to demonstrate the improvement using our revised algorithm. In the direction of future research, we discuss the comparison between the reordered point being fixed and the reordered point as a new variable.

In this paper, the multi-layer TDS (thin dielectric sheet) integral equation approach is first proposed. This method divides the geometric model into multiple thin layers and assumes the flux density to be constant with respect to the normal direction within each layer. Consequently, the number of unknowns is significantly reduced while the precision of the results could be maintained. Then, the multi-layer TDS integral approach is combined with the PEC (perfect electric conductor) boundary conditions together to handle scattering from dielectric coated PEC objects. This new procedure simplifies the coupled surface (for the conductor)–volume (for dielectric) integral to a surface–surface integral with much fewer unknowns. Furthermore, a remedy approach is also presented in this paper to improve the deteriorated precision for open composed structures due to the significant singular currents near the boundary edges. Compared with traditional PEC-TDS methods, the method presented in this paper can deal with ...

In this paper we consider the nonparametric estimation for a density and hazard rate function for right censored α-mixing survival time data using kernel smoothing techniques. Since survival times are positive with potentially a high concentration at zero, one has to take into account the bias problems when the functions are estimated in the boundary region. In this paper, gamma kernel estimators of the density and the hazard rate function are proposed. The estimators use adaptive weights depending on the point in which we estimate the function, and they are robust to the boundary bias problem. For both estimators, the mean squared error properties, including the rate of convergence, the almost sure consistency and the asymptotic normality are investigated. The results of a simulation demonstrate the excellent performance of the proposed estimators.

This paper presents a three-dimensional configuration-space (3D C-space) machining method for 5-axis finish machining of tessellated surfaces. To maximize the step-over distance, the curvature matched method (CM2) is used to approximate the cusp height and the step-over distance. A 3D C-space is then built for each cutter contact point (CC point). Every configuration set in this 3D C-space guarantees that the cutter is gouge-free and that the cusp height is less than the machining tolerance. The inclination angle λ by which the cutter is rotated about LY, the yaw angle ω by which the cutter is rotated about LZ and the height δ by which the cutter is lifted along the normal of the surface are three variables used to build the 3D C-space. Next, the optimal cutter orientation is obtained in this corresponding 3D C-space via a special optimization process. The ideal 3D C-space set, the initial 3D C-space set and the objective function of the optimization process are based on machine tool kinematics. Boundary functions are determined by the geometry feature of the 3D C-space. The penalty function method is employed as the optimization method. In this paper, the cutting accuracy is self-guaranteed to be less than the machining tolerance. The cutting speed is set to be as high as possible based on optimal cutter orientation and maximized step-over distance.

In this paper, work concerning robust D-stability analysis is considered for discrete descriptor systems with structured uncertainties and multiple time delays. A genetic algorithm is used to make the stability test of the main result more efficient. A delay-dependent robust D-stability criterion is proposed to ensure that all poles of the discrete multiple time-delay descriptor systems subject to uncertainties are located within a disk contained in the unit circle. It will be seen that the system considered in this paper is more general and the proposed robust D-stability criterion is less conservative and easier to check than those presented in recent research. Moreover, a delay-dependent criterion is derived to guarantee that the system is regular, impulse-free, and D-stable. Since the boundary test occurs during the check of the criteria, a genetic algorithm is used to make it more precise. Finally, an example is introduced to illustrate our main results.

This paper treats the problem of how to transform from global datum, for example, from the International Terrestrial Reference System (ITRS), to a local datum, for example, regional or national, for the practical case of the Lambert projection of the sphere or the ellipsoid-of-revolution to the cone. We design the two projection constants n(ϕ1, ϕ2) and m(ϕ1) for the Universal Lambert Conic projection of the ellipsoid-of-revolution. The task to transform from a global datum with respect to the ellipsoid-of-revolution EA,B 2 to local datum with respect to the alternative ellipsoid-of-revolution Ea,b 2, without local ellipsoidal height, is solved by an extended numerical example. Ideas in this paper could be of interest to those working with maps and coordinates transformation from global geodetic datum to local geodetic datum and vice versa, under the Universal Lambert Conic projection, and applicable to precise positioning and navigation, boundary demarcation and determination in the marine environment.

This paper presents a computer-aided modeling and simulation method for analyzing position, velocity, and acceleration of sliding objects on recreational waterslides. Safety and excitement levels of the object sliding down the waterslide are the two common criteria for waterslide design. Between the two, safety is far more critical than excitement level. Safety aspects of the waterslide design can be reasonably ensured; by restricting the sliding object, which stays within the physical boundary of the flume sections. In this paper, mathematical representations of a number of common flume sections are first created in parametric surfaces. These basic building blocks have also been implemented in Computer-Aided Design (CAD) tools, such as SolidWorks. A set of coupled differential equations based on Lagrange's equations of motion that describe the motion of the sliding object are derived, in which friction forces are included. These second order differential equations are then solved using Mathemati...

This paper examines normative and formative approaches toward describing normal work area. Squires’ model of normal work area is an example of a normative approach, which prescribes the shape of normal work area. Squires’ model has been taken as the starting point for more recent attempts to delineate reach boundaries in the workplace. However, his original paper does not present the derivation for his model or his claim that the distal boundary of his normal work area can be described by a prolate epicycloid. This paper presents the derivation for Squires’ model and shows that the resulting curve is not a prolate epicycloid, but a related form, a hypotrochoid. It then identifies shortcomings of normative models, like Squires’, notably the viability of the reach assumptions on which such normative models are based and their inability to deal with context-conditioned variability in the workplace. Finally, it examines the application of formative models, which attempt to identify constraints on the types of...

In this paper, we derive a new integral equation method for direct electromagnetic scattering in homogeneous media and present a numerical confirmation of the new method via a computer simulation. The new integral equation method is based on a paper written by DeSanto [1], originally for scattering from an infinite rough surface separating homogeneous dielectric half-spaces. Here, it is applied to a bounded scatterer, which can be an ohmic conductor or a dielectric, with some simplification of the continuity conditions for the fields. The new integral equation method is developed by choosing the electric field and its normal derivative as boundary unknowns, which are not the usual boundary unknowns. The new integral equation method may provide significant computational advantages over the standard Stratton–Chu method [2] because it leads to a 50% sparse, rather than 100% dense, impedance (collocation) matrix. Our theoretical development of the new integral equation method is exact.

Towards the end of his 1930 paper on boundary numbers and domains of sets Zermelo briefly discusses the questions of consistency and of the existence of an unbounded sequence of strongly inaccessible cardinals, deferring a detailed discussion to a later paper which never appeared. In a report to the Emergency Community of German Science from December 1930 about investigations in progress he mentions that some of the intended extensions of these topics had been worked out and were nearly ready for publication. Using manuscripts from his Nachlass, we exhibit essential features of these extensions.

One‐dimensional numerical simulation results of plane Gaussian electromagnetic pulses reflected from constantly moving and vibrating perfect conductors are provided in this paper. The computational data were obtained using the characteristic‐based algorithm with the aid of relativistic boundary conditions and characteristic variable boundary conditions. Since the perfect conductor can travel and vibrate simultaneously, the size of the grid cell immediately next to the boundary and the corresponding numerical time‐step are time‐dependent. The present numerical method has been shown to accurately handle such problems. In this paper both the reflected electric field intensities and the corresponding spectra are illustrated. The calculated Doppler shifts are found to have good agreement with the theoretical values.

In this paper, we establish relations between the sets of input and output boundaries, a set of weakly Pareto-efficient points and the boundary of the production possibility set. Theoretical results presented in the paper are illustrated by examples.

Topology is normally considered as independent of shape of spatial objects. This may not necessarily be true in describing relations between spatial objects in GIS. In this paper, we present proof that the topological relations between spatial objects are dependent on the shape of spatial objects. That is, that the topological relations of non-convex sets cannot be deformed to the topological relations of convex sets. The significant theoretical value of this paper is on its findings that topology of spatial objects is shape dependent. This indicates that when we want to describe topological relations between spatial objects in GIS, both topology and the shape of objects need to be considered. As a result, spatial data modeling, query and analysis based on the existing understanding of topology of spatial objects may need re-assessed. * Supported by the Hong Kong Polytechnic University (Grant Nos. Polyu 5071/01E and G-9051)

A novel scheme of external force for detecting the object boundary of medical image based on Snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our Snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent Snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.

This paper presents an investigation of velocity distribution in steady, uniform flows in smooth rectangular channels. Theoretical study and experimental data show that the near wall velocity distribution in 3-D channels cannot be represented well by the classical log-law where the shear velocities are identical on both sides of the equation (Tracy and Lester, US Department of Interior,Washington, DC, 1961, pp. A1-A18). This paper examines the appropriate expressions of two shear velocities that may be different. In the light of Tracy and Lester's work, this study found that when the measured near wall velocity and wall normal distance are normalized by the global shear velocity and the local shear velocity, then the near wall velocity can be described by the well-known wall function without an empirical coefficient. The basic mechanism is attributed to the concept proposed by Yang and Lim [J. Hydraul. Engng. ASCE 123 (1997) 684] that surplus mechanical energy is transported towards boundary along shortes...

This paper is drawn from research into architectural practice and discourse in colonial settings during modernism, to investigate the entangled and sometimes antagonistic relations between architectural, political and cultural contexts. The paper will show how the built boundary in ‘tropical’ sites has been the site of much architectural thought and experimentation. The nature of this experimentation is technical, and constructs differences in terms of certain physical aspects of the site, mostly regarding climate. Through design, the building boundary is configured to alter the climate's effect and make the interior more comfortable for western users. By examining how this boundary functions, however, it appears that far from being neutral the boundary works to structure (other) relations between the inside and outside of the building. These mirror the power relations between centre and periphery. The built boundary can also be seen as a production of unequal exchanges between these locations, exchanges ...

Let D be a smooth bounded domain in . Let f be a positive monotone increasing function on which satisfies the Keller–Osserman condition. It is well-known that the solutions of Δ u=f(u), which blow up at the boundary behave, to a first order approximation, like a function of dist(x,∂ D). In this paper we show that the second order approximation depends on the mean curvature of ∂ D. This paper is an extension of results in [4] which dealt with radially symmetric solutions. It extends also the results in [5] for f = tp .

Among the many areas of research that Professor Kawahara has been active in is the subject of open boundaries in which linear time-dependent dispersive waves are considered in an unbounded domain. The infinite domain is truncated via an artificial boundary B on which an open boundary condition (OBC) is imposed. In this paper, Higdon OBCs and Hagstrom–Hariharan (HH) OBCs are considered. Higdon-type conditions, originally implemented as low-order OBCs, are made accessible for any desired order via a new scheme. The higher-order Higdon OBC is then reformulated using auxiliary variables and made compatible for use with finite element (FE) methods. Methodologies for selecting Higdon parameters are also proposed. The performances of these schemes are demonstrated in two numerical examples. This is followed by a discussion of the HH OBC, which is applicable to non-dispersive media on cylindrical and spherical geometries. The paper extends this OBC to the “slightly dispersive” case.

This paper raises the question whether it is possible to develop a theory of bordering which will encompass the diverse types of border and boundary experience. I have previously argued that the only way to create a common language between the different disciplinary languages (including geographers, political scientists, anthropologists, sociologists, economists and others) is to create a common set of theoretical constructs and frameworks which can be used as a generalized explanatory model for understanding changing border/boundary phenomenon (Newman 2003). In essence, this paper reiterates a question asked long ago in one of the classic studies of international boundaries, namely how are boundaries (borders) to be redefined in the settings of contemporary time and place (Jones 1959).

System reliability evaluation for flow networks is an important issue for quality performance. This paper studies the system reliability that a given amount of multicommodity can be transmitted through a stochastic-flow network under the budget constraint, where each node and each arc has several possible capacities. Such reliability is named multicommodity reliability throughout this paper. A simple algorithm is proposed to generate all lower boundary points for (d^1, d^2,…,d(superscript p);C) where d(superscript i) is the demand of commodity i and C is the budget. The multicommodity reliability can then be calculated in terms of such points.

Possibility and algorithm of identification of boundary velocity based on the measurements of internal temperature is presented and studied in the paper. Procedure for solving the steady state inverse convection-diffusion heat transfer problem with potential fluid flow in 2D was worked out. The presented procedure employs sensitivity coefficient technique and finite element method. Due to the nonlinearity, the iterative algorithm was used for solving the inverse problem. The direct and inverse procedures and their solutions are discussed in the paper. The sensitivity of the estimation with respect to changes of selected parameters is also investigated. The presented analysis is directed at heat transfer processes in the ground with groundwater flow.

The goal of this paper is to provide a review of the interrelationship between grain boundary structure, chemistry, and failure. The main thrust of the paper is that one must consider structure and chemistry in order to assess various failure mechanisms and that one must also address these issues in high angle, asymmetric grain boundaries. One of the key themes of the paper is that the boundary is best considered as a chain of molecular or structural units and that, during such processes as fracture or sliding, the ability of the boundary to sample many of these units determines whether or not a material will ultimately fail. The ease of sampling different boundary structures will depend on the chemical composition of the boundary.

An essentially bounded function φ on the unit circle gives a continuous linear functional T φ on the Hardy space H 1 ρ(φ) denotes a set of all complex numbers s such that there exists at least one function which attains the norm of T φ− s In a previous paper, we showed that is empty or an open disc.Unfortunately we did not know when ρ(φ) is open or closed. In this paper, we study when ρ(φ) is open or closed. Moreover the functions in the Smirnov class N + whose real parts are nonnegative on the unit circle are described and studied. Then we give new characterizations of exposed points in the unit ball of H 1 and we determine when the sum of two inner functions is outer. As an result, we can describe all functions which have their Denjoy-Wolff points on the unit circle.

The problem of boundary feedback stabilization of rotating Timoshenko beam, arising from control of flexible robot arms, is studied in this paper. First, under gain adaptive direct strain feedback controls, a counterexample is given to show that the corresponding closed loop system is not asymptotically stable, which is contrary to traditional conjecture. The counterexample given in this paper also exemplifies an interesting result: certain two two-order linear partial differential equations with five homogeneous boundary conditions have non-trivial solutions. Then, with an additional boundary feedback control, the related energy of the closed loop system is proved to be strongly stable, or more precisely, the configuration of the beam can be exponentially stabilized with some suitable non-linear boundary feedback controls with adaptive gain.

Determining whether an assembly can be constructed from its components at the design stage potentially reduces downstream assembly problems. This determination can be accomplished by performing a disassembly analysis of the assembly′s geometric model. This paper presents two abstractions derived from the assembly′s geometric model that can determine the validity of the assembly: (1) the Assembly Topology Graph (ATG); and (2) the set of boundary components. The first abstraction, the ATG, is a graph whose nodes represent the components in the assembly and whose edges represent a non-null intersection of the convex hulls of component pairs. The second abstraction, the set of boundary components, represents components that intersect the boundary (or convex hull) of the assembly. These boundary components are typically the ones most accessible with respect to disassembly. This paper also discusses an algorithm, which utilizes the ATG to determine pair-wise interlocking components. If such component pairs are absent, then the disassembly sequence for the removal of components in the assembly is determined by analyzing the set of boundary components for disassembly. This procedure is repeated until all the components in the assembly are disassembled (for a valid assembly).

In this paper, we consider an inverse problem for the Mindlin–Timoshenko plate system, which is a strongly coupled two-dimensional system consisting of a wave equation and a system of isotropic ela...

Let (M,g) be a compact Riemann surface with smooth boundary. In this paper, using blow-up analysis, we prove the existence of an extremal function for a singular Trudinger–Moser inequality on (M,g).