Urban perimeters issues in low-density areas

In the domain of spatial planning, there is a concern to preserve the territory whilst ensuring a proper expansion of urban perimeters. Cities, towns and villages should be contained within urban perimeters for building and urbanization purposes. The concept of urban perimeter is defined as the closed polygonal line demarcating the continuous territory of urban land-use. The spatial planning instruments should define the urban land-use referring to areas totally or partially urbanized or built. Regarding low-density territories with a greater propensity to urban sprawl and population ageing, the previously mentioned rules are not always met. Thus, this study focuses on the case of the Interior region of Portugal classified as low-density territory. Here the number of inhabitants is decreasing with low demand for urban spaces. However, the urban perimeters were mainly defined without being based on territorial features, topographic mapping or ecological sensitive areas. Thus, for a diversity of aspects, there are inappropriate areas to build that were wrongly included as part of urban areas, creating as a result urban void. One main reason for this problem are the topographic conditions that don’t fit with the urbanization and building requirements in urban perimeters. In this sense, this research aims to describe the articulation between the urbanization and building processes, under the rules of the Municipal Master Plans, regarding the topographic features of urban perimeters. The conclusion shows that the most sloped areas are those that were less sought after for urbanization, however these zones comprise a significant part of the urban perimeters. Finally, there is the need to stress that in low-density territories, many urban voids will never be urbanized.

Deep Belief Network and Closed Polygonal Line for Lung Segmentation in Chest Radiographs

Due to the varying appearance in the upper clavicle bone region, sharp corner at the costophrenic angle, the presence of strong edges at the rib cage and clavicle and the lack of a consistent anatomical shape among different individuals, accurate segmentation of lung on chest radiographs remains challenging. In this work, we propose a novel segmentation method for lung segmentation, containing two subnetworks, where few manually delineated points are used as the approximate initialization. The first one is a preprocessing subnetwork based on a deep learning model (i.e. Deep Belief Network and K-Nearest Neighbor). The second one is a refinement subnetwork, designed to make the preprocessed result to be optimized by combining an improved principal curve method and a machine learning method. To prove the performance of the proposed method, several public datasets were evaluated with Dice Similarity Coefficient (DSC), overlap score (Ω), Sensitivity (Sen), Positive Predictive Value (PPV), global Error (E) and execution time (t). Compared with state-of-the-art methods, our method reaches superior segmentation performance.

Mechanical Characteristics of the Main Tower of a Polygonal Line Tower Cable-Stayed Bridge

The main tower of a polygonal line tower cable-stayed bridge bears most of the axial force transmitted by the stay cable and also bears the moment under certain unbalanced load. For a polygonal line tower cable-stayed bridge, the main tower has a bending corner and the direction of huge axial force transmission changes at this bending corner where the axis of the main tower changes. This study examined a cable-stayed bridge with a single cable plane in Shenyang and used model test and finite element numerical comparative analysis to analyze the mechanical properties of the key parts, including the main tower bending corner of the concrete polygonal line tower. The results show a serious stress concentration phenomenon at the bending corner of the main tower but a small range of high stress area. After the stiffening plate is set at the corner, the stress concentration coefficient of the bending corner section decreases and the stiffening plate eliminates the out-of-plane bending phenomenon of the tower wall at the middle span side as vertical tensile stress occurs in the stiffener at the bending corner. Based on these results, the design should be improved to increase the angle of the stiffening plate corner and appropriately strengthen the configuration of the vertical main tensile steel bar and the surface anticracking steel mesh inside the stiffening plate.

On Bernstein–Kantorovich invariance principle in Hölder spaces and weighted scan statistics

Let ξn be the polygonal line partial sums process built on i.i.d. centered random variables Xi, i ≥ 1. The Bernstein-Kantorovich theorem states the equivalence between the finiteness of E|X1|max(2,r) and the joint weak convergence in C[0, 1] of n−1∕2ξn to a Brownian motion W with the moments convergence of E∥n−1/2ξn∥∞r to E∥W∥∞r. For 0 < α < 1∕2 and p (α) = (1 ∕ 2 - α) -1, we prove that the joint convergence in the separable Hölder space Hαo of n−1∕2ξn to W jointly with the one of E∥n−1∕2ξn∥αr to E∥W∥αr holds if and only if P(|X1| > t) = o(t−p(α)) when r < p(α) or E|X1|r < ∞ when r ≥ p(α). As an application we show that for every α < 1∕2, all the α-Hölderian moments of the polygonal uniform quantile process converge to the corresponding ones of a Brownian bridge. We also obtain the asymptotic behavior of the rth moments of some α-Hölderian weighted scan statistics where the natural border for α is 1∕2 − 1∕p when E|X1|p < ∞. In the case where the Xi’s are p regularly varying, we can complete these results for α > 1∕2 − 1∕p with an appropriate normalization.

On the Cauchy problem with an initial point lying on the boundary of ordinary differential equation’s domain of definition

In this paper we investigate the existence of solution of the initial-value problem with an initial point located at the boundary of the domain of definition for the first-order differential equation. This initial-value problem differs from the one accepted in classical theory, where the initial point is always internal for domain. Our aim is to find such conditions for the right-hand side of the equation and the boundary that would guarantee the existence or absence of this solution. In its previous article the authors used the standard Euler polygonal line method to solve this problem and described all cases when this method is used to get the desired answer. The polygonal line method, having certain advantages (constructibility, the ability to use a computer), requires for its implementation that both the equation and the domain of its definition meet certain restrictions, which inevitably narrows the class of acceptable equations. In this paper, we attempt to maximize the results obtained earlier, and for this purpose we use a completely different approach. The original equation is extended in such a way that the boundary initial-value problem becomes an ordinary internal initial-value problem, for which the standard Peano theorem is applied. To answer the question whether the solution of the modified initial-value problem is also the solution of the original boundary initial-value problem, so-called comparison theorems and differential inequalities are applied. This article is an independent study, not based on our previous work. For the sake of completeness, new proofs are given for previously obtained results, which are based on a new approach. As a result, we expanded the class of equations under consideration, removed the previous requirements for convexity and smoothness of boundary curves, and added cases that could not be considered using the polygonal line method. This work closes a certain gap that exists in the literature on the existence or absence of solutions to the boundary initial-value problem.

Experimental and analytical investigation on the nonlinear behaviors of glulam moment-resisting joints composed of inclined self-tapping screws with steel side plates

Glulam moment-resisting joint composed of inclined self-tapping screws with steel side plates were designed and its nonlinear moment-rotational skeleton curve was predicted by taking nonlinear load ( P)–deformation ( u) relationships of all moment-resisting components into considerations within step-wise linear calculation process. P-u relationships of all moment-resisting components were estimated by the fundamental shear joint tests or appropriate empirical relationships, and they were approximated by the tetra polygonal line curves or bi-linear curves. The extended Normalized Characteristic Loop model, which was originally developed for reinforced concrete construction, was applied to describe the hysteresis loops. For predicting failure load, the design equations for a mechanical joint loaded with inclination to the grain direction were applied. Three replications of T-shaped beam-column joint specimens were fabricated using Canadian spruce glulam beam and column. Connections of steel plates to glulam members were all composed of full-threaded inclined self-tapping screws. Static push-pull cyclic loading tests were conducted and observed behaviors were compared with step-wise linear analytical results. Agreements between predicted nonlinear behaviors and observed ones were good on the whole.

An Adaptive CIP-FEM for the Polygonal-Line Grating Problem

This paper is concerned with the diffraction by a polygonal-line grating. We develop a continuous interior penalty finite element method based on the truncation of the nonlocal boundary operators for solving the problem. An a posteriori error estimate is derived for the method. The truncation parameter is determined through the truncation error of the a posteriori error estimate. Numerical experiments are also presented to show the efficiency and robustness of the proposed adaptive algorithm.