This study focuses on developing methodologies to predict the service life of a pavement marking material based on its retroreflectivity. Data from the 2002 National Transportation Product Evaluation Program (NTPEP) pavement marking... more
This study focuses on developing methodologies to predict the service life of a pavement marking material based on its retroreflectivity. Data from the 2002 National Transportation Product Evaluation Program (NTPEP) pavement marking material test deck in Mississippi are used for model development and model validation. The smoothing spline method and time series modeling are applied to estimate the service lives of different types of materials based on the assumption of a required minimum retroreflectivity value. The same models can also predict the retroreflectivity values at future times for a pavement marking product based on its retroreflectivity values in the past. The validation of the models shows satisfactory accuracy. As demonstrated in a case study, the predicted service lives of the marking materials can be used in life-cycle cost comparisons for selecting pavement marking material.
In this paper, a new fractional spline method of non-polynomial form have been considered to solve special linear fractional boundary-value problems. Using this fractional spline function a few consistency relations are derived for... more
In this paper, a new fractional spline method of non-polynomial form have been considered to solve special linear fractional boundary-value problems. Using this fractional spline function a few consistency relations are derived for computing approximations to the solution of the problem. Convergence analysis and error estimates of this methods are discussed. Numerical results are provided to demonstrate the superiority of our methods.
Derivatives are a very important tool of computations in an engineering practice on the graphics structures. B-Spline functions are defined recursively, so the direct computation is very difficult. In this article new direct proof of the... more
Derivatives are a very important tool of computations in an engineering practice on the graphics structures. B-Spline functions are defined recursively, so the direct computation is very difficult. In this article new direct proof of the formula used for simpler direct computation is shown. The paper also presents own method of programming derivatives of NURBS curves by means of the proven formula which is implemented in German engineering software RFEM 3D.
Transit oriented design (TOD) – an increase in density around transit stations - has arisen in many of Australia’s capital cities as a way to encourage mass transit ridership as well as to efficiently utilise the increase in foot and... more
Transit oriented design (TOD) – an increase in density around transit stations - has arisen in many of Australia’s capital cities as a way to encourage mass transit ridership as well as to efficiently utilise the increase in foot and vehicle traffic that transit stations create. However, the implementation of TODs in Melbourne has faced strong opposition due to residents’ perception that the disamenities of a TOD will outweigh the benefits resulting in negative impacts on property prices. This research analyses the relationship between proximity to a TOD and residential home prices. Results indicate that proximity to a TOD is positively related to property prices, even after controlling for neighborhood factors such as street connectivity and overall land use mix. By testing a variety of transformations of distance, we find that the benefits of TOD proximity extend approximately 1250 meters from the Box Hill station. From a methodological standpoint, we find that more flexible treatments of distance variables in spatial autoregressive and spline models produce better model fit and lead to results more in line with urban economic theory.
This paper presents research on contemporary tile vaulting, demonstrated through a large-scale prototype structure that minimizes formwork by using fiberglass splines. Autoclaved-aerated concrete (AAC) bricks, whose porosity maximizes... more
This paper presents research on contemporary tile vaulting, demonstrated through a large-scale prototype structure that minimizes formwork by using fiberglass splines. Autoclaved-aerated concrete (AAC) bricks, whose porosity maximizes cohesion with gypsum mortar, were laid over a hybrid steel and flexible fiberglass "spline" guide-work system, which offered significant advantages. Bent elastic splines can be used to approximate the desired construction geometry. This pushes the limits of compression-only structures that can be built efficiently, without compromising a desire for building evocative forms. The "Volta Porosa" prototype and its formwork system were researched, designed and constructed by students in an interdisciplinary workshop on thin shell construction. This paper will discuss the innovative combination of traditional methods with new materials, as well as the design and construction process for the prototype vault.
This paper describes the conceptual framework of a general strategy for developing an engine crankshaft based on computer-aided innovation, together with an introduction to the methodologies from which our strategy evolves. It begins with... more
This paper describes the conceptual framework of a general strategy for developing an engine crankshaft based on computer-aided innovation, together with an introduction to the methodologies from which our strategy evolves. It begins with a description of two already popular disciplines, which have their roots in computer science and natural evolution: evolutionary design (ED) and genetic algorithms (GAs). A description of some optimization processes in the field of mechanical design is also presented. We explain our approach to multi-objective optimization and show how tools like the Pareto diagram can help in identifying conflicts. The concepts presented here are exemplified through the optimization of a combustion engine crankshaft. The main premise of the paper is the possibility to optimize the imbalance of a crankshaft using tools developed in this methodology. This study brings together techniques that have their origins in the fields of optimization and new tools for innovation. We reflect on how computers can have an active role in the conceptual design process, and explain how TRIZ (Theory of Inventive Problem Solving) can enrich the discipline of ED. The aim of our research is to extend the search for solutions with GAs and present creative, innovative alternatives to the designer. Similarities between GAs and TRIZ regarding ideality and evolution are presented. We also explain how geometric optimization systems (size, shape, topology and topography) offer hints about the next generation of optimization tools. The role of splines in this context is found to be closely integrated with GAs in enabling this development on a computer-aided design and engineering (CAD&CAE) software interface, and in enabling integration with Java programming language for automation of the development.
The regularized long wave equation (RLW) is solved numerically by using the quintic B-spline Galerkin finite element method. The same method is applied to the time-split RLW equation. Comparison is made with both analytical solutions and... more
The regularized long wave equation (RLW) is solved numerically by using the quintic B-spline Galerkin finite element method. The same method is applied to the time-split RLW equation. Comparison is made with both analytical solutions and some previous results. Propagation of solitary waves, interaction of two solitons are studied.
The detection of double edges in x-ray images of lumbar vertebrae is of prime importance in the assessment of vertebral injury or collapse that may be caused by osteoporosis and other spine pathology. In addition, if the above double-edge... more
The detection of double edges in x-ray images of lumbar vertebrae is of prime importance in the assessment of vertebral injury or collapse that may be caused by osteoporosis and other spine pathology. In addition, if the above double-edge detection process is conducted within an automatic framework, it would not only facilitate inexpensive and fast means of obtaining objective morphometric measurements on the spine, but also remove the human subjectivity involved in the morphometric analysis. This paper proposes a novel force-formulation scheme, termed as Pressurized Open Directional Gradient Vector Flow snakes, to discriminate and detect the superior and inferior double edges present in the radiographic images of the lumbar vertebrae. As part of the validation process, this algorithm is applied to a set of 100 lumbar images and the detection results are quantified using analyst-generated ground truth. The promising nature of the detection results bears testimony to the efficacy of the proposed approach
The response of an aircraft in flight to atmospheric gusts is one of the dynamic response problems, which controls the wing design and dimensioning of large aircraft. In the present work, dynamic analysis of an aircraft subjected to a... more
The response of an aircraft in flight to atmospheric gusts is one of the dynamic response problems, which controls the wing design and dimensioning of large aircraft. In the present work, dynamic analysis of an aircraft subjected to a one-dimensional random gust is carried out. Power spectral density (PSD) of gust is represented by both von Karman and Dryden mathematical gust model. Finite element model (FEM) of a typical aircraft is generated using Finite Element software. Aero dynamic modelling is also carried out. The Doublet-Lattice method (DLM) is used for interfering lifting surfaces in subsonic flow. The analysis was performed using the advanced FEM software. Natural frequencies are computed and mode shapes are identified. Continuous gust is applied on the aircraft and the dynamic acceleration and bending moments are computed at critical locations. This work provides dynamic loads due to gust using von Karman and Dryden models.
In this article, we will follow the history of splines, digital methods that have characterized the architectural design process since the last decade of the twentieth century. We will describe their evolutions since the beginning as... more
In this article, we will follow the history of splines, digital methods that have characterized the architectural design process since the last decade of the twentieth century. We will describe their evolutions since the beginning as analogical tools for boat construction in the eighteenth century, to its passage to digital within the automotive industry. Then the relationship with the aerospace industry, and the evolution which from digital animation, have led nurbs, subdivision surfaces and t-splines to become everyday computational tools within architecture workflow. Recent developments on t-splines, following their acquisition by Autodesk, will lead us to a reflection on the relationship between software houses, which develop tools, and architects, who are now dependent on them. Therefore, we will consider the need to develop open-source methods, as Pixar did with Opensubdiv, as knowledge and responsibility shared solution.
In this work we present a new scheme for Hermite interpolation of a given set of planar points with a conic spline curve. The conic spline is represented as a piecewise rational quadratic Bezier curve, which depends on local tension... more
In this work we present a new scheme for Hermite interpolation of a given set of planar points with a conic spline curve. The conic spline is represented as a piecewise rational quadratic Bezier curve, which depends on local tension parameters in order to control the shape of each section. We define a fairness functional family as the set of linear combinations of the arc length and the bending energy of the conic section. The values of the tension parameters minimizing this energy functional determine the fairest curve. Applying a subdivision scheme for conic splines introduced in [5], we obtain good approximations of the functional and its derivative, which are used for an efficient numerical computation of its minimum value. If we choose an specific linear combination of the functional we can show that the proposed Hermite conic spline scheme is invariant to rigid changes of coordinates and uniform scaling, reproduces arcs of circles and satisfies the fairness requirements listed in [7]. The fair Hermite conic spline scheme has been implemented in MatLab and a gallery of results is shown.
En este trabajo presentamos un nuevo esquema para la interpolací on de Hermite de un conjunto de puntos en el plano por medio de una curva spline racional cuadrática. El spline cónico es representado como una curva racional cuadrática de Bézier, el cual depende de un parámetro de tensión local que controla la forma de cada sección. Definimos una familia de funcionales de fairness como el conjunto las combinaciones lineales de la longitud de arco y de la energía elástica de la sección cónica. El valor del parámetro de tensión que minimiza el funcional corresponde a la curva fair. Aplicando el esquema de subdivisión para splines cónicos propuesto en [5] obtenemos buenas aproximaciones numéricas del funcional y sus derivadas. Se demuestra además que el funcional alcanza su valor mínimo en cada uno de los segmentos del spline y utilizamos un algoritmo numériconum´numérico para hallarlo. Escogiendo una determinada combinación lineal en el funcional se demuestra que el esquema spline cónico de Hermite propuesto es invariante bajo transformaciones rígidas y homotecias, reproduce arcos de circunferencia y satisface las condiciones presentadas en [7]. El esquema ha sido implementado en MatLab y se presenta una galería de salidas gráficas del código.
Merging NURBS surfaces together and extending existing ones are common problems in CAD systems. Extending existing surface is usually done by creating a new separate surface and applying some merging function – result is one continuous... more
Merging NURBS surfaces together and extending existing ones are common problems in CAD systems. Extending existing surface is usually done by creating a new separate surface and applying some merging function – result is one continuous surface. In this paper, full description of a method of direct extending existing surfaces is introduced. The extension of the surface is recomputed during its construction, and the NURBS surfaces are immediately C 1 connected
A novel technique for designing curves on surfaces is presented. The design specifications for this technique derive from other works on curvature continuous surface fairing. Briefly stated, the technique must provide a computationally... more
A novel technique for designing curves on surfaces is presented. The design specifications for this technique derive from other works on curvature continuous surface fairing. Briefly stated, the technique must provide a computationally efficient method for the design of surface curves that is applicable to a very general class of surface formulations. It must also provide means to define a smooth natural map relating two or more surface curves. The resulting technique is formulated as a geometric construction that maps a space curve onto a surface curve. It is designed to be coordinate independent and provides isoparametric maps for multiple surface curves. Generality of the formulation is attained by solving a tensorial differential equation formulated in terms of local differential properties of the surfaces. For an implicit surface, the differential equation is solved in three-space. For a parametric surface the tensorial differential equation is solved in the parametric space as...
Abstract. 1 It is well-known that certain non bandlimited signals such as splines can be reconstructed from uniformly spaced samples similar to bandlimited signals. This usually requires noncausal IIR filters. We revisit this result and... more
Abstract. 1 It is well-known that certain non bandlimited signals such as splines can be reconstructed from uniformly spaced samples similar to bandlimited signals. This usually requires noncausal IIR filters. We revisit this result and consider extensions such as derivative sampling theorems and pulse sampling theorems. It turns out that spline-like signals can often be reconstructed from joint sampling of amplitude and derivative using only FIR filters. We also briefly consider discrete time versions of these results. 1.
Conventional optical character recognition systems, designed to recognize linearly aligned text, perform poorly on document images that contain multi-oriented text lines. This paper describes a novel technique that can extract text lines... more
Conventional optical character recognition systems, designed to recognize linearly aligned text, perform poorly on document images that contain multi-oriented text lines. This paper describes a novel technique that can extract text lines of arbitrary curvature and align them horizontally. By invoking the spatial regularity properties of text, adjacent components are grouped together to obtain the text lines present in the image. To align each identified text line, we fit a B-spline curve to the centroids of the constituent characters and normal vectors are computed all along the resulting curve. Each character is then individually rotated such that the corresponding normal vector is aligned with the vertical axis. The method has been tested on images that contain text laid out in various forms namely arc, wave, triangular and combination of these with linearly skewed text lines. It yields 97.3% recognition accuracy on text strings where state-of-the-art OCRs fail before alignment.
Much research is being directed toward investigating links between quantitative characteristics of the retinal vasculature and a variety of outcomes to identify biomarkers. The interest for retinal biomarkers lies in the fact that the... more
Much research is being directed toward investigating links between quantitative characteristics of the retinal vasculature and a variety of outcomes to identify biomarkers.
The interest for retinal biomarkers lies in the fact that the retina is easily observed via fundus photography. Outcomes considered for research of biomarkers in the literature include conditions such as diabetes and lacunar stroke, and also cognitive performance and genetic expression [1–5]. The need for measuring large volumes of images, needed to power biomarker discovery studies, makes semiautomatic software systems desirable. This chapter reports recent algorithms developed by the VAMPIRE group for vasculature detection and quantification, including recent developments on landmark detection. We focus on accuracy and validation issues, and, importantly, the conditions for comparing meaningful results from different algorithms. This work is a part of VAMPIRE (Vasculature Assessment and Measurement Platform for Images of the REtina), which is an international collaboration growing a software suite for automatic morphometric measurements of the retinal vasculature.
Inflation is defined as a sustained increase in the general level of price for goods and services. Some of the events that led to inflation in Indonesia is rising fuel prices, rising prices of meat and chili. Inflation has negative... more
Inflation is defined as a sustained increase in the general level of price for goods and services. Some of the events that led to inflation in Indonesia is rising fuel prices, rising prices of meat and chili. Inflation has negative impact, because decreased purchasing power. So that the inflation model is needed. Modeling inflation can be use regression models. The approach can be performed with nonparametric regression, one of method of nonparametric regression is spline method. In this case, use three predictors to modeling inflation using spline multivariable. The predictors are price of rice, price of chicken, and price of chili. Obtained multivariable spline models with R-square of 93.94% with optimal m = 2 (quadratic) for 1 knots.
Local perturbations nearby contours strongly perturb the final result of processing remotely sensed images (RSI). It is common to establish a priori data to aid the estimation process. One can move some steps forward by means of a... more
Local perturbations nearby contours strongly perturb the final result of processing remotely sensed images (RSI). It is common to establish a priori data to aid the estimation process. One can move some steps forward by means of a deformable model, for example, the snake model. In up to date research, the deformable contour is represented via B-spline snakes, which allows local control, concise depiction, and the use of fewer parameters. The estimation of edges with sub-pixel accuracy via a global B-spline depiction depends on determining the edge according to a Maximum Likelihood (ML) agenda and using the observed information likelihood. This practice guarantees that outliers present in data will be cleaned out. The data likelihood is calculated as a result of the observation model comprising both orientation and position data. Experiments where this procedure and the traditional spline interpolation have revealed that the algorithm introduced outperforms the conventional method fo...
This paper summarizes three recent, novel algorithms developed within VAMPIRE, namely optic disc and macula detection, artery-vein classification, and enhancement of binary vessel masks, and their performance assessment. VAMPIRE is an... more
This paper summarizes three recent, novel algorithms developed within VAMPIRE, namely optic disc and macula detection, artery-vein classification, and enhancement of binary vessel masks, and their performance assessment. VAMPIRE is an international collaboration growing a suite of software tools to allow efficient quantification of morphological properties of the retinal vasculature in large collections of fundus camera images. VAMPIRE measurements are currently mostly used in biomarker research, i.e., investigating associations between the morphology of the retinal vasculature and a number of clinical and cognitive conditions
The emergence of applications to capture, process, store, and transmit motion capture (MoCap) signal has raise the interest in research community to investigate and devise better techniques for parameterization and compression of MoCap... more
The emergence of applications to capture, process, store, and transmit motion capture (MoCap) signal has raise the interest in research community to investigate and devise better techniques for parameterization and compression of MoCap signal. In this work, we present a novel and efficient method for parametric representation and compression of motion signal for skeletal animation. The method exploits the temporal coherence of motion signal using quadratic Bézier curve (QBC) fitting. The method treats the rotational and translation variations of a joint in a sequence of frames as input points in N-dimensional Euclidean space. The input points are parameterized and approximated using QBC least square fitting. Break and fit criterion is used to minimize the number of curve segments required to fit the data. Precise control of fitting accuracy is achieved by user specified tolerance of error limit. We compared the performance of the proposed method with principal component analysis and wavelet transform based methods of MoCap signal compression. The method leads to smaller storage and better visual quality compared to other methods. The low degree of QBC ensures computationally efficient fitting algorithm, especially for the real-time applications.
In contrast to the extensively researched modeling of plant architecture, the modeling of plant organs largely remains an open problem. In this paper, we propose a method for modeling lobed leaves. This method extends the concept of... more
In contrast to the extensively researched modeling of plant architecture, the modeling of plant organs largely remains an open problem. In this paper, we propose a method for modeling lobed leaves. This method extends the concept of sweeps to branched skeletons. The input of the model is a 2D leaf silhouette, which can be defined interactively or derived from a scanned leaf image. The algorithm computes the skeleton (medial axis) of the leaf and approximates it using spline curves interconnected into a branching structure (sticky splines). The leaf surface is then constructed by sweeping a generating curve along these splines. The orientation of the generating curve is adjusted to properly capture the shape of the leaf blade near the extremities and branching points of the skeleton, and to avoid selfintersections of the surface. The leaf model can be interactively modified by editing the shape of the silhouette and the skeleton. It can be further manipulated in 3D using functions th...
Local perturbations nearby contours strongly perturb the final result of processing remotely sensed images (RSI). It is common to establish a priori data to aid the estimation process. One can move some steps forward by means of a... more
Local perturbations nearby contours strongly perturb the final result of processing remotely sensed images (RSI). It is common to establish a priori data to aid the estimation process. One can move some steps forward by means of a deformable model, for example, the snake model. In up to date research, the deformable contour is represented via B-spline snakes, which allows local control, concise depiction, and the use of fewer parameters. The estimation of edges with sub-pixel accuracy via a global B-spline depiction depends on determining the edge according to a Maximum Likelihood (ML) agenda and using the observed information likelihood. This practice guarantees that outliers present in data will be cleaned out. The data likelihood is calculated as a result of the observation model comprising both orientation and position data. Experiments where this procedure and the traditional spline interpolation have revealed that the algorithm introduced outperforms the conventional method for Gaussian as well as Salt and Pepper noise. Keywords— sub-pixel accuracy; surveillance; image processing; machine learning; B-Splines; interpolation I. INTRODUCTION One of the greatest challenges of modeling remotely sensed images is the mixed pixel problem, that is, the level of spatial detail captured is less than the amount of expected details [13, 26, 27, 28]. This sub-pixel heterogeneity is important, but not readily capable of being known. In a traditional manner, each pixel is classified into one of many land cover types (hard classification), implying that land cover exactly fits within the bounds of one or multiple pixels. However, several pixels consist of a mixture of different classes. The solution to the mixed pixel problem typically centers on soft classification, which allows proportions of each pixel to be partitioned
