Geometric Design

This report presents an algorithm for predicting the safety performance of a rural two-lane highway. The accident prediction algorithm consists of base models and accident modification factors for both roadway segments and at-grade intersections on rural two-lane highways. The base models provide an estimate of the safety performance of a roadway or intersection for a set of assumed nominal or base conditions. The accident modification factors adjust the base model predictions to account for the effects on safety for roadway segments of lane width, shoulder width, shoulder type, horizontal curves, grades, driveway density, two-way left-turn lanes, passing lanes, roadside design and the effects on safety for at-grade intersections of skew angle, traffic control, exclusive left- and right-turn lanes, sight distance, and driveways. The accident prediction algorithm is intended for application by highway agencies to estimate the safety performance of an existing or proposed roadway. The...

Deformations are a powerful tool for shape modeling and design. We present a new model for producing controlled spatial deformations, which we term Simple Constrained Deformations (Scodef). The user defines a set of constraint points, giving a desired displacement and radius of influence for each. Each constraint point determines a local B-spline basis function centered at the constraint point, falling to zero for points beyond the radius. The deformed image of any point in space is a blend of these basis functions, using a projection matrix computed to satisfy the constraints. The deformation operates on the whole space regardless of the representation of the objects embedded inside the space. The constraints directly influence the final shape of the deformed objects, and this shape can be fine-tuned by adjusting the radius of influence of each constraint point. The computations required by the technique can be done very efficiently, and real-time interactive deformation editing on current workstations is possible.

Crash data are collected through police reports and integrated with road inventory data for further analysis. Integrated police reports and inventory data yield correlated multivariate data for roadway entities (e.g., segments or intersections). Analysis of such data reveals important relationships that can help focus on high-risk situations and coming up with safety countermeasures. To understand relationships between crash frequencies and associated variables, while taking full advantage of the available data, multivariate random-parameters models are appropriate since they can simultaneously consider the correlation among the specific crash types and account for unobserved heterogeneity. However, a key issue that arises with correlated multivariate data is the number of crash-free samples increases, as crash counts have many categories. In this paper, we describe a multivariate random-parameters zero-inflated negative binomial (MRZINB) regression model for jointly modeling crash ...

Just by adjusting the control points iteratively, progressive-iterative approximation presents an intuitive and straightforward way to fit data points. It generates a curve or patch sequence with finer and finer precision, and the limit of the sequence interpolates the data points. The progressive-iterative approximation brings more flexibility for shape controlling in data fitting. In this paper, we design a local progressive-iterative approximation format, and show that the local format is convergent for the blending curve with normalized totally positive basis, and the bi-cubic B-spline patch, which is the most commonly used patch in geometric design. Moreover, a special adjustment manner is designed to make the local progressive-iterative approximation format is convergent for a generic blending patch with normalized totally positive basis. The local progressive-iterative approximation format adjusts only a part of the control points of a blending curve or patch, and the limit curve or patch interpolates the corresponding data points. Based on the local format, data points can be fit adaptively.

An analysis of fatal crashes involving pedestrians in Delhi, India, from 2006 to 2009 that used a geographic information system showed clusters of crashes at certain locations. An evaluation of the characteristics of the built environment around the high crash location clusters was necessary. This paper presents an analysis of the built environment factors that influenced the safety of pedestrians. Locations surveyed included roads around the fatal crash clusters of pedestrians. Factors that influenced the number of fatal crashes of pedestrians were analyzed with negative binomial regression. Types of locations were categorized into locations with a flyover and without a flyover. Results showed that an increase in traffic volume by 1% would increase pedestrian fatal crashes by 1.6% at locations with a flyover and by 0.9% at locations without a flyover. Arterial roads with more traffic volume, more road lanes, and higher speed tended to have more fatal crashes. Locations where median...

Studies dealing with the effect of road geometry on accidents by vehicle maneuvers have been reported, mostly for western countries and a few for Asia. However, no such studies have been reported for Singapore. Traffic accidents arising from head-to-side and head-to-rear maneuvers at four-legged signalized intersections in Singapore were investigated. Based on accident data at intersections in the southwestern part of Singapore from 1992 to 1999, the factors affecting such accidents were explored using zero-altered probability models. Specific roadway geometrics as well as traffic control and regulatory factors that influence the two categories of accidents were identified. It was found that head-toside accidents tend to decrease if there is an adjacent intersection within 200 m and if bus stops along the approach are provided with bays. On the other hand, longer sight distances and the presence of a pedestrian refuge tend to increase this type of accident. Higher speed limits were found to reduce the instances of zero head-to-side accidents. It was also found that head-to-rear accidents decrease when the intersections are under adaptive signal control but increase when surveillance cameras are present. There is also some evidence to suggest that the presence of an uncontrolled left-turn channel, the existence of medians wider than 2 m, higher approach volumes, and more phases per cycle all contribute to higher instances of accidents by both maneuver types.

Symbolic computation of NURBS plays an important role in many areas of NURBS-based geometric computation and design. However, any nontrivial symbolic computation, especially when rational B-splines are involved, would typically result in B-splines with high degrees. In this paper we develop degree reduction strategies for NURBS symbolic computation on curves. The specific topics we consider include zero curvatures and critical curvatures of plane curves, various ruled surfaces related to space curves, and point/curve bisectors and curve/curve bisectors.

Most transit networks are designed empirically. For bus networks this process 1s often satisfactory because bus routes and networks are very dependent on local conditions, and they can be easily modified, allowing easy corrections of problems which line design may cause in operations. However, with transit systems which have extensive infrastructure, most typically metro lines and networks, corrections are extremely difficult to make. Development of an optimal network and avoidance of design features which result in operational problems are therefore of great importance. Yet, the experiences from the design and operation of such large older metro systems as London, Moscow, New York, Pan's and Tokyo, or from numerous recently built medium-size metro systems, such as Hong Kong, San Francisco, Sao Paulo and Washington, remain largely unknown to the designers of new metro networks. This paper presents a theoretical analysis of transit lines and networks and its applications. The focus is on network geometry and operational characteristics. The basic design and operational elements, such as geometric forms of lines, headways, schedules, etc., are discussed in general terms, valid for any mode; however, the main focus is on metro systems because of the particular importance of these analyses for fixed, permanent systems.

The geometric interpolation algorithm is proposed by Maekawa et al. in [Maekawa T, Matsumoto Y, Namiki K. Interpolation by geometric algorithm. Computer-Aided Design 2007;39:313-23]. Without solving a system of equations, the algorithm generates a curve (surface) sequence, of which the limit curve (surface) interpolates the given data points. However, the convergence of the algorithm is a conjecture in the reference above, and demonstrated by lots of empirical examples. In this paper, we prove the conjecture given in the reference in theory, that is, the geometric interpolation algorithm is convergent for a blending curve (surface) with normalized totally positive basis, under the condition that the minimal eigenvalue λ min (D k) of the collocation matrix D k of the totally positive basis in each iteration satisfies λ min (D k) ≥ α > 0. As a consequence, the geometric interpolation algorithm is convergent for Bézier, B-spline, rational Bézier, and NURBS curve (surface) if they satisfy the condition aforementioned, since Bernstein basis and B-spline basis are both normalized totally positive.

The paper presents a systematic methodology for synthesis of link geometry for interference free planar mechanisms with a given set of kinematic dimensions. All links are assumed to be flat, of same thickness; all the joints are assumed to be of revolute type. For this class of ...

Fast Fourier transform (FFT) is widely applied in OFDM trance-receiver communications system. Hence Efficient FFT algorithm is always considered. This paper proposed FPGA realization of high resolution high speed low latency floating point adder/subtractor for FFT in OFDM trance-receiver. The design was implemented for 32 bit pipelined adder/subtractor which satisfied IEEE-754 Standard for floating-point Arithmetic. The design was focused on the trade-off between the latency and speed improvement as well as resolution and silicon area for the chip implementation. In order to reduce the critical path and decrease the latency, the novel structure was designed and investigated. Consequently, synthesis report indicated the latency of 4 clock cycles due to each stage operated within just one clock cycle. The unique structure of designed adder well thought out resulted 6691 equivalent gate count and lead us to obtain low area on chip. The synthesis Xilinx ISE software provided results representing the estimated area and delay for design when it is pipelined to various depths. The report shows the minimum delay of 3.592 ns or maximum frequency of 278.42 MHz.

This study aimed at finding the effects of road geometry and cross-section variables on numbers of accidents. In addition, a methodology to combine variables by using decision trees was developed. Combination variables for road geometry and cross section were created by using the chi-square automatic interaction detection algorithm. Two negative binomial models were developed: one with homogeneous road segments and the other with 1-km road segments. Homogeneous road segments were divided on the basis of the horizontal alignment of the road. They were either curved or straight. The accuracy of the negative binomial model with homogeneous road segments was compared with that of the negative binomial model with 1-km road segments. The negative binomial model using homogeneous road segments was found to be the more accurate of the two models. The model with homogeneous road segments was used to draw conclusions with regard to the effect of variables on the number of accidents. Combinati...

This paper demonstrates how to approximate the boundary of the clear zone adjacent to a roadway alignment, based only on horizontal sight distance considerations. The alignment is divided into subproblems, and the clear zone boundary for each subproblem is approximated by a piecewise-linear space curve. The algorithms for this approximation are speci®cally designed to avoid numerical instability. Pseudocode versions of the algorithms are presented for the entire method. The errors in this approach are quite small compared to the expected errors generated while surveying and constructing roadways, and the error bound is shown to converge to zero uniformly as the parameter governing the resolution of the algorithm is made smaller. Ó

Any highway should be able to offer driving safety. In this sense, it is especially valued that roadways satisfy drivers' needs of riding with safety and render an adequate workload. Available sight distance along a road alters drivers' expectancies and the way ...

Manual surveying methods have long been used in the field of highway engineering to determine the cross-slope, and longitudinal grade of an existing roadway. However, these methods are slow, tedious and labor intensive. Moreover, manual survey methods almost always require partial or full lane closure resulting in traffic delays, increase in costs, and inconvenience to the travelling public. In 2003, the Florida Department of Transportation (FDOT) acquired a state-ofthe-art Multi-Purpose Survey Vehicle (MPSV) which combines the advantage of an inertial profiler with the additional ability to simultaneously collect images, cross-slope, longitudinal grade, curvature, rutting, and roughness at highway speed.

Recently a variety of algorithms for the approximation of parametric curves and surfaces by algebraic representations have been developed. We test three of these methods on several test cases, keeping track of time and memory consumption of the implementations and the quality of the approximation. Additionally we discuss some qualitative aspects of the different methods. XXX 1 xxx and xxx (eds.), pp. 1-4.

A 3D drawing methodology based on voxel-graphics was applied to the design of multi-component engineering systems, such as fuel-cells. Using this methodology and Java-technology a graphics user interface (GUI) for a fuel-cell simulator program was developed and used in simulations of large fuel-cell stacks. The GUI is capable to setup, run and monitor simulations remotely from a web-browser. The geometric design module was implemented using 3D voxel sculpting methodology and data visualization, which is prototyped after 2D pixel graphics systems. The developed approach was primarily aimed at the design of complex multi-component engineering systems. However, the flexibility of voxel-based geometry representation enables one to use this technique for both 3D geometric design and visualization of unstructured volume data. Examples of both applications are presented, with the focus on fuel-cell stack simulations.

Two railroad curve transition spiral shapes are compared with respect to their dynamic performance: the traditional linear shape and an improved shape intended to provide optimal dynamic performance. The improved shape is attractive because it gives much better dynamic performance and flows from an improved way of thinking about spirals. The improved spiral design method and spiral shape to be

The need for wireless communication has driven the communication systems to high performance. However, the main bottleneck that affects the communication capability is the Fast Fourier Transform (FFT), which is the core of most modulators. This paper presents FPGA implementation of pipeline digit-slicing multiplier-less radix 2 2 DIF (Decimation In Frequency) SDF (single path delay feedback) butterfly for FFT structure. The approach taken; in order to reduce computation complexity in butterfly multiplier, digit-slicing multiplier-less technique was utilized in the critical path of pipeline Radix-2 2 DIF SDF FFT structure. The proposed design focused on the trade-off between the speed and active silicon area for the chip implementation. The multiplier input data was sliced into four blocks each one with four bits to process at the same time in parallel. The new architecture was investigated and simulated with MATLAB software. The Verilog HDL code in Xilinx ISE environment was derived to describe the FFT Butterfly functionality and was downloaded to Virtex II FPGA board. Consequently, the Virtex-II FG456 Proto board was used to implement and test the design on the real hardware. As a result, from the findings, the synthesis report indicates the maximum clock frequency of 555.75 MHz with the total equivalent gate count of 32,146 is a marked and significant improvement over Radix 2 2 DIF SDF FFT butterfly. In comparison with the conventional butterfly architecture design which can only run at a maximum clock frequency of 200.102 MHz and the conventional multiplier can only run at a maximum clock frequency of 221.140 MHz, the proposed system exhibits better results. It can be concluded that on-chip implementation of pipeline digit-slicing multiplier-less butterfly for FFT structure is an enabler in solving problems that affect communications capability in FFT and possesses huge potentials for future related works and research areas. Key words— Pipelined digit-slicing multiplier-less; Fast Fourier Transform (FFT); Verilog HDL; Xilinx; Radix 22 DIF SDF FFT.

The Michaelis-Menten model has and continues to be one of the most widely used models in many diverse fields. In the biomedical sciences, the model continues to be ubiquitous in biochemistry, enzyme kinetics studies, nutrition science and in the pharmaceutical sciences. Despite its wide ranging applications across disciplines, design issues for this model are given short shrift. This paper focuses on design issues and provides a variety of optimal designs of this model. In addition, we evaluate robustness properties of the optimal designs under a variation in optimality criteria. To facilitate use of optimal design ideas in practice, we design a web site for generating and comparing dfferent types of tailor-made optimal designs and user-supplied designs for the Michaelis-Menten and related models. --

The precise analysis and accurate measurement of harmonic provides a reliable scientific industrial application. However, the high performance DSP processor is the important method of electrical harmonic analysis. Hence, in this research work, the effort was taken to design a novel high-resolution single 1024-point fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) processors for improvement of the harmonic measurement techniques. Meanwhile the project is started with design and simulation to demonstrate the benefit that is achieved by the proposed 1024-point FFT/IFFT processor. Pipelined structure is incorporated in order to enhance the system efficiency. As such, a pipelined architecture was proposed to statically scale the resolution of the processor to suite adequate trade-off constraints. The proposed FFT makes use of programmable fixed-point/floating-point to realize higher precision FFT.

Analysis This research work focuses on the design of a high-resolution fast Fourier transform (FFT) /inverse fast Fourier transform (IFFT) processors for constraints analysis purpose. Amongst the major setbacks associated with such high resolution, FFT processors are the high power consumption resulting from the structural complexity and computational inefficiency of floating-point calculations. As such, a parallel pipelined architecture was proposed to statically scale the resolution of the processor to suite adequate trade-off constraints. The quantization was applied to provide an approximation to address the finite word-length constraints of digital signal processing (DSP). An optimum operating mode was proposed, based on the signal-to-quantization-noise ratio (SQNR) as well as the statistical theory of quantization, to minimize the trade-off issues associated with selecting the most application-efficient floating-point processing capability in contrast to their resolution quality.

This paper presents on-chip implementation of high speed low latency floating point adder /subtractor with high accuracy performance for FFT in OFDM transceiver. However due to high performance and high resolution, the floating point adder is matched with power network applications as well. The design was implemented for 32-bit pipelined adder/subtractor which satisfied IEEE-754 Standard for floating –point Arithmetic. The design is focused on the trade-off between the latency and speed improvement as well as resolution and silicon area for the chip implementation. In order to reduce the critical path and decrease the latency, the novel structure was designed and investigated. Consequently, synthesis report indicating the latency of 4 clock cycles due to each stage operate within just one clock cycle. The unique structure of designed adder well thought out. The synthesis software provides results representing the estimated area and delay for design when it is pipelined to various depths.

The recursive and non-recursive comb filters are commonly used as decimators for the sigma delta modulators. This paper presents the analysis and design of low power and high speed comb filters. The comparison is made between the recursive and the non-recursive comb filters with the focus on high speed and saving power consumption. Design procedures and examples are given by using Matlab and Verilog HDL for both recursive and non-recursive comb filter with emphasis on frequency response, transfer function and register width. The implementation results show that non-recursive comb filter has capability of speeding up the circuit and reducing power compared to recursive one when the decimation ratio and filter order are high. Using Modified Carry Look-ahead Adder for summation and also apply pipelined filter structure makes it more compatible for DSP application.

In the present paper an evolution of a hybrid optimization method is described to find the geometric design parameters and the joint angles when some end-effector poses are prescribed. The problem is solved by minimizing the sum of the deviation squares between the prescribed poses and the real poses of the considered endeffector. The evolution of the proposed algorithm is developed in MatLab software. The developed method is applied in two degrees of freedom spatial serial RR manipulator, in three numerical examples, where one, two or three endeffector poses are prescribed. Furthermore, a comparison of the results between the evolution of the method on MatLab and the initial one based on Fortran demonstrates a higher efficiency of the Matlab approach, regarding the minimum value of the fitness function as well as the computational time.