Approximate Degree Reduction of NURBS Curves and Surfaces: An Integrated Approach

1994 ◽  
Author(s):  
Srinivasa P. Varanasi ◽  
Athamaram H. Soni
Keyword(s):  
Shape Control ◽  
Data Exchange ◽  
Data Transfer ◽  
Integrated Approach ◽  
Free Form ◽  
Aircraft Industry ◽  
Trimmed Surfaces ◽  
Curves And Surfaces ◽  
High Degree ◽  
Boundary Curves

Abstract Data exchange between different CAD systems usually requires conversion between different representations of free-form curves and surfaces. Also, trimmed surfaces give rise to high degree boundary curves. Accurate conversion of these forms becomes necessary for reliable data transfer. Also important is the issue of shape control, specially in the aircraft industry. The objective of this paper is to investigate conversion methods and effect of shape control on the design and choice of such methods.

Constrained Shape Scaling of Trimmed NURBS Surfaces

1999 ◽  
Author(s):  
Pifu Zhang ◽  
Caiming Zhang ◽  
Fuhua (Frank) Cheng
Keyword(s):  
Data Exchange ◽  
Surface Deformation ◽  
Current Data ◽  
Free Form ◽  
Test Results ◽  
Nurbs Surface ◽  
Curvature Distribution ◽  
The Given ◽  
Boundary Curves

Abstract A method to scale and deform a trimmed NURBS surface while holding the shape and size of specific features (trimming curves) unchanged is presented. The new surface is formed by scaling the given surface according to the scaling requirement first; and then attaching the (original) features to the scaled NURBS surface at appropriate locations. The attaching process requires several geometric operations and constrained free-form surface deformation. The resulting surface has the same features as the original surface and same boundary curves as the scaled surface while reflecting the shape and curvature distribution of the scaled surface. This is achieved by minimizing a shape-preserving objective function which covers all the factors in the deformation process such as bending, stretching and spring effects. The resulting surface maintains a NURBS representation and, hence, is compatible with most of the current data-exchange standards. Test results on several car parts with trimming curves are included. The, quality of the resulting surfaces is examined using the highlight line model.

The Geometric Modeling and Interrogation System Praxiteles

1995 ◽  
Vol 11 (02) ◽  
pp. 117-132
Author(s):  
S. L. Abrams ◽  
L. Bardis ◽  
C. Chryssostomidis ◽  
N. M. Patrikalakis ◽  
S. T. Tuohy ◽  
...  
Keyword(s):  
Geometric Modeling ◽  
Data Exchange ◽  
Free Form ◽  
Mathematical Methods ◽  
Initial Shape ◽  
Marine Propellers ◽  
Curves And Surfaces ◽  
Design Requirements ◽  
And Performance

After establishment of design requirements and creation of an initial shape, the design process of free form shapes should include interrogation and fairing until a desired shape, with appropriate geometric and performance characteristics, is achieved. Afterwards, the quality of the manufactured product can be determined by comparing measured data with the design model. To permit automated design and manufacturing, mathematical methods and algorithms for the creation, interrogation, fairing, and inspection of curves and surfaces have been developed and integrated into a computer system called Praxiteles. The general layout of Praxiteles, along with a description of design capabilities, is presented. This description covers the areas of input, output, approximation and conversion for data exchange, a summary of some shape creation methods, and a description of some advanced interactive interrogation, fairing, and inspection methods for NURBS curves and surfaces. Examples illustrate some of the features of the system, as applied in the design and inspection of marine propellers. Recommendations for future development of the system are also presented.

Theoretical and experimental study of motion and sinking time of Saxon Bowls

2022 ◽  
Author(s):  
Jaikumar Sankar ◽  
Liu Yang
Keyword(s):  
Motion Tracking ◽  
Volumetric Flow Rate ◽  
Free Form ◽  
Motion Path ◽  
Time Interval ◽  
Flow Profile ◽  
Bernoulli’S Equation ◽  
Hole Radius ◽  
Coefficient Of Discharge ◽  
High Degree

Abstract This work focuses on investigating the time of sinking of a Saxon bowl proposed by ‘International Young Physicists’ Tournament in 2020. A quasi-static model is built to simulate the motion path of the bowl and predict the sinking time subsequently. The model assumes an open axisymmetric bowl with a hole in its base. The hole is modelled as a pipe for which the flow profile is governed by a modified Bernoulli’s equation which has a Coefficient of Discharge (C_d) added to account for energy losses. The motion of the entire bowl is assumed to be in quasi-static equilibrium for an infinitesimal time interval to calculate the volumetric flow rate through the hole. The model is used to predict the sinking times of various bowls against independent variables - hole radius, bowl dimensions, mass of bowl, mass distribution of bowl, and Coefficient of Discharge - and predict the motion path of bowls of different, axisymmetric geometries. Characterisation of C_d was done by draining a bowl filled with water and measuring the time taken to do so. Experimental verification was completed through measuring sinking times of 3D printed hemispherical bowls of the different variables in water. Motion tracking of bowls with different geometries was done using computational pixel tracking software to verify the model’s predictive power. Data from experiments for sinking time against the variables corroborate with the model to a great degree. The motion path tracked, matched the modelled motion path to a high degree for bowls of different shapes, namely a hemisphere, cylinder, frustum, and a free-form axisymmetric shape. The work is poised for an undergraduate level of readership.

scholarly journals Morphology, Stability, and Application of Lycopene Microcapsules Produced by Complex Coacervation

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Glaucia A. Rocha-Selmi ◽  
Carmen S. Favaro-Trindade ◽  
Carlos R. F. Grosso
Keyword(s):  
Encapsulation Efficiency ◽  
Gum Arabic ◽  
Average Diameter ◽  
Stability Test ◽  
Free Form ◽  
Complex Coacervation ◽  
The Stability ◽  
Processing And Storage ◽  
High Degree ◽  
And Storage

The interest in lycopene has increased in recent years due to studies that associate it with the reduction in risk of developing cardiovascular diseases and cancer. However, due to its high degree of unsaturation, this carotenoid is inclined to isomerize and oxidize during processing and storage, making it difficult to use in the food industry. Microencapsulation can improve this situation, increasing its stability and making incorporation into food formulations possible. Thus, the aim of this study was to microencapsulate lycopene by complex coacervation using gelatin and gum Arabic as the encapsulating agents. The microcapsules were evaluated based on the encapsulation efficiency and their morphology and then submitted to a stability test and applied in cake making. Most of the systems studied presented spherical microcapsules with defined walls. The encapsulation efficiency values were above 90%, and the average diameter of the capsules ranged from 61 to 144 μm. The stability test showed that microencapsulation offered greater protection to the lycopene as compared to its free form. The application of nonfreeze dried coacervated microcapsules in cake making was satisfactory, but the color transference was low when freezedried coacervated microcapsules were used.

ERROR BOUNDED VARIABLE DISTANCE OFFSET OPERATOR FOR FREE FORM CURVES AND SURFACES

1991 ◽  
Vol 01 (01) ◽  
pp. 67-78 ◽  
Author(s):  
GERSHON ELBER ◽  
ELAINE COHEN
Keyword(s):  
Approximation Algorithms ◽  
Error Bound ◽  
Free Form ◽  
Global Error Bound ◽  
New Methods ◽  
Curves And Surfaces ◽  
Polygon Mesh ◽  
Finite Set ◽  
Variable Distance ◽  
Improved Accuracy

Most offset approximation algorithms for freeform curves and surfaces may be classified into two main groups. The first approximates the curve using simple primitives such as piecewise arcs and lines and then calculates the (exact) offset operator to this approximation. The second offsets the control polygon/mesh and then attempts to estimate the error of the approximated offset over a region. Most of the current offset algorithms estimate the error using a finite set of samples taken from the region and therefore can not guarantee the offset approximation is within a given tolerance over the whole curve or surface. This paper presents new methods to globally bound the error of the approximated offset of freeform curves and surfaces and then automatically derive new approximations with improved accuracy. These tools can also be used to develop a global error bound for a variable distance offset operation and to detect and trim out loops in the offset.

JCAMP-DX for NMR

1993 ◽  
Vol 47 (8) ◽  
pp. 1093-1099 ◽  
Author(s):  
Antony N. Davies ◽  
Peter Lampen
Keyword(s):  
Spectral Data ◽  
Data Exchange ◽  
Data Transfer ◽  
Nmr Imaging ◽  
Successful Implementation ◽  
Independent Data ◽  
Imaging Data ◽  
Loss Of Information ◽  
Storage Media ◽  
Different Origin

Following the development and publication of the JCAMP-DX protocol 4.24 and its successful implementation in the field of infrared spectroscopy, data exchange without loss of information, between systems of different origin and internal format, has become a reality. The benefits of this system-independent data transfer standard have been recognized by workers in other areas who have expressed a wish for an equivalent, compatible standard in their own fields. This publication details a protocol for the exchange of Nuclear Magnetic Resonance (NMR) spectral data without any loss of information and in a format that is compatible with all storage media and computer systems. The protocol detailed below is designed for spectral data transfer, and its use for NMR imaging data transfer has not as yet been investigated.

scholarly journals Using Mobile Elements as Dynamic Bridges in Sparse Wireless Sensor Networks

2014 ◽  
pp. 107
Author(s):  
Hoang Dang Hai ◽  
Thorsten Strufe ◽  
Pham Thieu Nga ◽  
Hoang Hong Ngoc ◽  
Nguyen Anh Son ◽  
...  
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Data Exchange ◽  
Data Transfer ◽  
Mobile Elements ◽  
Sensor Nodes ◽  
Pollution Monitoring ◽  
Wireless Sensor ◽  
Mobile Nodes ◽  
Road Distance

Sparse  Wireless  Sensor  Networks  using several  mobile  nodes  and  a  small  number  of  static sensor  nodes  have  been  widely  used  for  many applications,  especially  for  traffic-generated  pollution monitoring.  This  paper  proposes  a  method  for  data collection and forwarding using Mobile Elements (MEs), which are moving on predefined trajectories in contrast to previous works that use a mixture of MEsand static nodes. In our method, MEscan be used as data collector as well as dynamic bridges for data transfer. We design the  trajectories  in  such  a  way,  that  they  completely cover  the  deployed  area  and  data  will  be  gradually forwarded  from  outermost  trajectories  to  the  center whenever  a  pair  of MEs contacts  each  other  on  an overlapping road distance of respective trajectories. The method  is based  on  direction-oriented  level  and  weight assignment.  We  analyze  the  contact  opportunity  for data  exchange  while MEs move.  The  method  has  been successfully tested for traffic pollution monitoring in an urban area.

scholarly journals Contemporary art thesauri in the context of the teaching profession development

2021 ◽  
Vol 53 (5) ◽  
pp. 32-47
Author(s):  
Larisa Yu. Kalinina ◽  
◽  
Dmitry V. Ivanov ◽  
Nikolai A. Nikitin ◽  
◽  
...  
Keyword(s):  
Contemporary Art ◽  
Interdisciplinary Approach ◽  
Integrated Approach ◽  
Teaching Profession ◽  
Professional Roles ◽  
Economic Changes ◽  
Cultural Activities ◽  
Education Levels ◽  
Research Findings ◽  
High Degree

Introduction. The problem of identifying the role of contemporary art thesauri in the teaching profession development has become aggravated in the context of global socio-economic changes, apparently irreversible after the COVID-19 pandemic. Contemporary art, actively exploring the reality of the digital age, makes it possible to comprehend the essence of the new in education, clearly see the ideal of a person who is in demand by the society of the 2020s, and choose a way to overcome the crisis of the teaching profession, which is no longer limited by the framework of person-to-person duality but is fundamentally open due to technology. The research purpose is to generalize scientific ideas for the study of contemporary art thesauri as a tool for developing the teaching profession in the cultural-educational space of the 21st century. The research methodology includes the thesaurus, interdisciplinary and integrated approaches; identification and systematization of units of knowledge about contemporary art through thesauri influencing the development of the profession of a teacher. The use of a thesaurus approach made it possible to identify and systematize units of knowledge about contemporary art and its educational opportunities that coincide in one way or another. An interdisciplinary approach showed the mechanism of integrating disciplines studied by future teachers with the space of modern artistic culture. An integrated approach was used to view contemporary art as a hierarchical system of a high degree of complexity in specific historical and psychological aspects. The research results contain a generalized description of the process of integrating contemporary art into education: the transition from a teacher’s professionalism to transprofessionalism through the introduction into the widespread practice of approaches that have resulted from the activities of representatives of creative professions; increasing the significance of a teacher as an organizer of cultural activities in the context of distance learning, with the emergence of new professional roles; the formation of concepts reflecting the commonality of thinking of a teacher and an author of artworks. Findings. Contemporary art thesauri help pedagogical education get to a higher level due to a new understanding of the profession of a teacher: as developing from professionalism to transprofessionalism through the assimilation of knowledge about the formation of a professional in the art sphere (“alien” becomes “own”), focused on organizing students’ cultural activities using distance technologies and new professional roles, explaining itself in terms of pedagogy and art. The field of application of research findings is the improvement of educational programs at all education levels (from the preschool establishment to university) in accordance with the requirements of state standards.

Free-Form Modeling in Bilateral Brep and CSG Representation Schemes

1998 ◽  
Vol 08 (05n06) ◽  
pp. 537-575 ◽  
Author(s):  
Jai Menon ◽  
Baining Guo
Keyword(s):  
Shape Control ◽  
Tangent Plane ◽  
Free Form ◽  
Unified Approach ◽  
Dual Representation ◽  
Surface Patches ◽  
Low Degree ◽  
Wide Range ◽  
Algebraic Patches ◽  
Direct Term

This paper presents a unified approach for incorporating free-form solids in bilateral Brep and CSG representation schemes, by resorting to low-degree (quadratic, cubic) algebraic surface patches. We develop a general CSG solution that represents a free-form solid as a boolean combination of a direct term and a complicated delta term. This solution gives rise to the trunctet-subshell conditions, under which the delta term computation can be obviated. We use polyhedral smoothing to construct a Brep consisting of quadratic algebraic patches that meet with tangent-plane continuity, such that the trunctet-subshell conditions are guaranteed automatically. This guarantee is not currently available for cubic patches. The general CSG solution thus applies whenever trunctet-subshell conditions are violated, e.g. sometimes for cubic patches or sometimes for patches of any degree that are subject to shape control operations. Manifold solids of arbitrary topology can be represented in our dual representation system. Ensuing CSG constructs are parallel processed on the RayCasting Engine to support a wide range of solid modeling applications, including general sweeping, Minkowski operations, NC machining, and touch-sense probing.

Transdisciplinary Research in Sustainable Scientific Education in the Field of Urbanism and Architecture

2014 ◽  
pp. 264-276
Author(s):  
Svetlana Perović
Keyword(s):  
Urban System ◽  
Integrated Approach ◽  
Transdisciplinary Research ◽  
Autonomous Action ◽  
Sustainable Improvement ◽  
Urban Issues ◽  
Control And Management ◽  
High Degree ◽  
Collaborative Knowledge

The chapter presents a case study based on transdisciplinary research, which was conducted at the Faculty of Architecture in Podgorica and is an innovation in architectural and urban practice of higher education in Montenegro. The study is based on the view that autonomous action of disciplines in the case of architecture and urbanism as multidisciplinary activities is limited, and an integrated approach to solving complex problems in the urban system is required. A global approach to research and solving urban issues is an important actor of sustainable development, where universities are central in this process. Collaborative educational discourses with a high degree of cooperation can develop an adequate platform for responses to the complex issues of the urban system. Producing experts with a developed awareness of a comprehensive understanding of the problem and transdisciplinary collaborative knowledge can strongly contribute to sustainable improvement, control, and management of urban spaces.

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