Computer-aided Design Applications Research Articles

Computer reconstruction of 19th century trousers

PurposeDesigning of clothes using the historical prototypes is very popular in contemporary practice. The purpose of this paper is to apply 2D and 3D computer-aided design (CAD) systems to reconstruct the historical pattern block and get the virtual image in accordance with the prototypes. New algorithm has been proved for men trousers taken from the nineteenth century.Design/methodology/approachOur approach is to develop a method of CAD to reconstruct historical trousers through analyzing and rebuilding of historical algorithms used to pattern blocks making, old anthropometrical database, and the pattern blocks shaping. Trousers construction, methods of trousers shaping by hands, body sizes schedule, manuals of 36 pattern cutting systems, and its sketches from nineteenth century have been analyzed. Then, by means of parameterization of historical pattern blocks, we have developed the universal trousers pattern cutting algorithm. The final step of the research has been devoted to virtual fitting technology that helps to determine the differences between historical trousers chosen as prototype and virtual image reconstructed by 3D CAD.FindingsThe authors have developed the parametrical module of 2D CAD and expanded the application of 3D CAD to re-designing of completely new object such as nineteenth century trousers pattern blocks in accordance with the historical method of shaping by hands. The conformity between the style of historical trousers and the virtual images reconstructed from two resources – pattern block and sketch silhouette – has been achieved.Originality/valueThis study demonstrated the contemporary approach to historical garments reconstruction by means of CAD. This study should help researchers of historical costume and practical specialists in apparel industry to apply historical heritage in a contemporary way.

Development of Deformed Computer-Aided Design Geometries for the Sixth Drag Prediction Workshop

A method for modifying the shape of digital geometry representations used in computer-aided design applications according to experimental pointwise deflection data is described. In the pilot study presented here, the method is applied to the computer-aided design geometry of an aircraft wing that is deformed using measured deflections obtained from the associated wing model during a wind-tunnel test. The method provides various advantages in computational fluid dynamics and other applications. Numerical grids generated on the deformed geometry yield an improved correlation of computational fluid dynamics results to wind-tunnel data without the need for aeroelastic computations, which require coupling to a structural model. Additionally, the method is beneficial in aerodynamic optimization, where the optimized shape is usually given in the form of a computational fluid dynamics surface mesh or nodal deflections that, for further processing or manufacturing purposes, need to be transferred into a computer-aided design geometry description. The paper presents an application to NASA’s Common Research Model transport aircraft configuration, where deformation measurements from a test campaign in the European Transonic Wind Tunnel are processed to provide deformed computer-aided design geometries for the Sixth AIAA Computational Fluid Dynamics Drag Prediction Workshop.

A Quadratic Trigonometric Nu Spline with Shape Control

A significant curve modeling technique has been introduced with a view to its applications in geometric modeling, computer graphics and computer-aided design. It is a new spline method using quadratic trigonometric functions with well-controlled shape influences of parameters introduced through geometric continuity of order two. The proposed curve model owns the best possible geometric properties such as convex hull, partition of unity, affine invariance and variation diminishing. A quadratic normally has three control points giving lesser flexibility to one piece of curve. However, a cubic has four control points giving higher flexibility to one piece of curve. In the proposed scheme, we have introduced a quadratic trigonometric with four control points. Thus, the proposed quadratic trigonometric has embedded geometric features of cubic/cubic trigonometric. The proposed spline method, constrained with Nu spline like GC2 smoothness, produces a quadratic trigonometric Nu spline (QTNS) with interesting shape control locally and globally. The method is helpful for a variety of shape effects, like point tension, interval tension or global tension. It also produces a quadratic trigonometric alternative to cubic/cubic trigonometric spline because of having four control points in its piecewise description.

Preliminary Clinical Application of Removable Partial Denture Frameworks Fabricated Using Computer-Aided Design and Rapid Prototyping Techniques.

The aim of this study was to explore the application of computer-aided design and rapid prototyping (CAD/RP) for removable partial denture (RPD) frameworks and evaluate the fitness of the technique for clinical application. Three-dimensional (3D) images of dentition defects were obtained using a lab scanner. The RPD frameworks were designed using commercial dental software and manufactured using selective laser melting (SLM). A total of 15 cases of RPD prostheses were selected, wherein each patient received two types of RPD frameworks, prepared by CAD/RP and investment casting. Primary evaluation of the CAD/RP framework was performed by visual inspection. The gap between the occlusal rest and the relevant rest seat was then replaced using silicone, and the specimens were observed and measured. Paired t test was used to compare the average thickness and distributed thickness between the CAD/RP and investment casting frameworks. Analysis of variance test was used to compare the difference in thickness among different zones. The RPD framework was designed and directly manufactured using the SLM technique. CAD/RP frameworks may meet the clinical requirements with satisfactory retention and stability and no undesired rotation. Although the average gap between the occlusal rest and the corresponding rest seat of the CAD/RP frameworks was slightly larger than that of the investment casting frameworks (P < .05), it was acceptable for clinical application. RPD frameworks can be designed and fabricated directly using digital techniques with acceptable results in clinical application.

The application of CAD / CAM technology in Dentistry

Information and communication technologies have found their application in the healthcare sector, including the frameworks of modern dentistry. CAD / CAM application in dentistry is the process by which is attained finished dental restoration through fine milling process of ready ceramic blocks. CAD / CAM is an acronym of english words Computer-Aided-Design (CAD) / Computer-Aided-Manufacture (CAM), respectively dental computer aided design and computer aided manufacture of inlays, onlays, crowns and bridges. CAD / CAM technology essentially allows you to create a two-dimensional and three-dimensional models and their materialization by numerical controlled machines. In order to operate more efficiently, reduce costs, increase user/patient satisfaction and ultimately achieve profits, many dental offices in the world have their attention focused on implementation of modern IT solutions in everyday practice. In addition to the specialized clinic management software, inventory control, etc., or hardware such as the use of lasers in cosmetic dentistry or intraoral scanning, recently the importance is given to the application of CAD / CAM technology in the field of prosthetic. After the removal of pathologically altered tooth structure, it is necessary to achieve restoration that will be most similar to the anatomy of a natural tooth. Applying CAD / CAM technology on applicable ceramic blocks it can be obtained very quick, but also very accurate restoration, in the forms of inlays, onlays, bridges and crowns.The paper presents the advantages of using this technology as well as satisfaction of the patients and dentists by using systems as: Cercon, Celay, Cerec, Lava, Everest, which represent imperative of modern dentistry in creating fixed dental restorations.

Application of computer-aided design and 3D-printed navigation template in Locking Compression Pediatric Hip PlateΤΜ placement for pediatric hip disease.

To investigate the feasibility and accuracy of a drill template based on computer-aided design (CAD) and 3D printing technology for the placement of screws in Locking Compression Pediatric Hip Plate (LCP-PHP). LCP-PHP was used in 11 children [5 with femoral neck fracture and 6 with development dysplasia of hip (DDH)]. Using the CT data, the proximal femur model was created by a 3D printer. Fracture reduction and the placement of the screw in the femoral neck and the LCP-PHP were simulated by the computer. The navigation template was designed by the software to match the proximal femur. After the feasibility of the 3D model operation was demonstrated before the operation, the guide pins and the screws were inserted with the help of the navigate template in the operation. During surgery, the navigation template for each case was matched to the bony markers of the proximal femur. With the help of the template, in femoral neck fracture cases, three screws could be accurately inserted into the femoral neck to implant the LCP-PHP and stabilize the fracture. The template for DDH includes all operation parameters and steps for proximal femoral varus rotation and shortening osteotomy, which made the surgery much easier to perform. Radiographs taken after surgery showed that the postoperative results closely corresponded to the preoperative computer simulation. The average time taken for LCP-PHP placement was 26.5min; radiography was used during surgery only for an average of 6.0 times. Postoperative radiographs showed good results. With the use of CAD and 3D printing technology, accurate placement of individualized navigation template of LCP-PHP can be achieved. This technology can reduce intraoperative damage to the femoral neck epiphysis, decrease operation time, reduce intraoperative hemorrhage, and decrease radiation exposure to patients and personnel during the surgery.

Fractional order linear time invariant system stabilization by brute-force search

Fractional calculus increases their applications in system design and analysis problems because of providing more realistic modeling of real systems. Owing to computational complexity of fractional calculus, the computer-aided design and analysis methods are required for engineering applications of fractional order systems. This study presents a numerical method for parametric robust stabilization of fractional order systems by employing single-parameter perturbation. This method implements a fractional order perturbation strategy on the basis of brute-force search technique for system stabilization problems. In order to meet a predefined minimum argument root design specification, the proposed algorithm searches for a desired placement of the minimum argument characteristic root within the first Riemann sheet by performing iterative perturbations of the fractional order. This approach can provide a straightforward numerical solution for robust stabilization problems of fractional order systems by employing an order perturbation scheme. Moreover, a possible utilization of a fractional order derivative operator as a system stabilizer is theoretically discussed. Illustrative examples show the utilization of the proposed stabilization algorithms for computer-aided fractional order system design applications.

Embedding the script language into optical simulation software

Integration of the Python script language into computer-aided design and simulation applications is considered. By the example of the physically correct optical simulation application, an approach based on the unified entity interface for domain objects is proposed. In particular, a scheme is proposed to extend the application with new types of parametric objects by writing extension classes that are simple in structure. Special attention is paid to making API user-friendly and ensuring compliance with the object-oriented programming principles.

Application of Computer Support for Design of Shaft Furnaces – Cupolas

Designing a machine’s constructions and an object’s structures is one of the areas of technology design. The complexity of the structure is defined by the technology for which it is used. Following the theory of construction and mechanisms, the full characteristics of a machine or device is defined by its shape and operating parameters. The shape reflects geometry. As a result of using the correct parameters, the construction should functional correctly (which means according to its general principles of operation). The project of any structure is a creative process performed by a team of designers and constructors. The contemporary design is not solely based on the personal preferences of engineers. More and more scientific and computerized design methods are being introduced to this process. They are characterized as computer-aided systems and are based on algorithms, programs, and IT equipment. This article presents the methodological application of computer-aided design on an example of the design of shaft furnaces that are used in foundries as cast iron smelters. These furnaces, called cupolas, have again become objects of interest for research. In the design of the cupola construction, Autodesk Inventor techniques were used.

Inducing production rules to extend existing design grammars: The parse/derive method

ABSTRACTGraph-rewriting is a promising computation model for computer-aided design (CAD) applications that operate on graph-based design models. Graph-rewriting-based CAD systems rely on predefined production rules. These rules encode the set of possible actions that may be taken within the design process to make changes to the current design. This paper presents a method for automatically inducing new production rules from existing sample designs. The methods applicability is illustrated in context of conceptual spacecraft design. Results gained from experiments, where existing rules were deliberately left out and had to be rediscovered, show that the induced rules are often similar or identical to the original rules.

Relative Binding Free Energy Calculations Applied to Protein Homology Models.

A significant challenge and potential high-value application of computer-aided drug design is the accurate prediction of protein-ligand binding affinities. Free energy perturbation (FEP) using molecular dynamics (MD) sampling is among the most suitable approaches to achieve accurate binding free energy predictions, due to the rigorous statistical framework of the methodology, correct representation of the energetics, and thorough treatment of the important degrees of freedom in the system (including explicit waters). Recent advances in sampling methods and force fields coupled with vast increases in computational resources have made FEP a viable technology to drive hit-to-lead and lead optimization, allowing for more efficient cycles of medicinal chemistry and the possibility to explore much larger chemical spaces. However, previous FEP applications have focused on systems with high-resolution crystal structures of the target as starting points-something that is not always available in drug discovery projects. As such, the ability to apply FEP on homology models would greatly expand the domain of applicability of FEP in drug discovery. In this work we apply a particular implementation of FEP, called FEP+, on congeneric ligand series binding to four diverse targets: a kinase (Tyk2), an epigenetic bromodomain (BRD4), a transmembrane GPCR (A2A), and a protein-protein interaction interface (BCL-2 family protein MCL-1). We apply FEP+ using both crystal structures and homology models as starting points and find that the performance using homology models is generally on a par with the results when using crystal structures. The robustness of the calculations to structural variations in the input models can likely be attributed to the conformational sampling in the molecular dynamics simulations, which allows the modeled receptor to adapt to the "real" conformation for each ligand in the series. This work exemplifies the advantages of using all-atom simulation methods with full system flexibility and offers promise for the general application of FEP to homology models, although additional validation studies should be performed to further understand the limitations of the method and the scenarios where FEP will work best.

Post-traumatic zygomatic osteotomy and orbital floor reconstruction

Purpose Post-traumatic zygomatic osteotomy, fracture reduction, and orbital floor reconstruction pose many challenges for achieving a predictable, accurate, safe, and aesthetically pleasing result. This paper aims to describe the successful application of computer-aided design (CAD) and additive manufacturing (AM) to every stage of the process – from planning to surgery. Design/methodology/approach A multi-disciplinary team was used – comprising surgeons, prosthetists, technicians, and designers. The patient’s computed tomography scan data were segmented for bone and exported to a CAD software package. Medical models were fabricated using AM; for diagnosis, patient communication, and device verification. The surgical approach was modelled in the virtual environment and a custom surgical cutting guide, custom bone-repositioning guide, custom zygomatic implant, and custom orbital floor implant were each designed, prototyped, iterated, and validated using polymer AM prior to final fabrication using metal AM. Findings Post-operative clinical outcomes were as planned. The patient’s facial symmetry was improved, and their inability to fully close their eyelid was corrected. The length of the operation was reduced relative to the surgical team’s previous experiences. Post-operative scan analysis indicated a maximum deviation from the planned location for the largest piece of mobilised bone of 3.65 mm. As a result, the orbital floor implant which was fixed to this bone demonstrated a maximum deviation of 4.44 mm from the plan. Originality/value This represents the first application of CAD and AM to every stage of the process for this procedure – from diagnosis, to planning, and to surgery.

Effects of 3D CAD applications on the design creativity of students with different representational abilities

The purpose of the present study was to elucidate the auxiliary effects that the application of three-dimensional computer-aided design (3D-CAD) had on students’ creative design, and the differences in the effects of 3D-CAD on students with different representational abilities (RAs). An unequal-group pretest-posttest quasi-experiment design was developed to analyze 215 students studying in an anonymous senior high school in Taipei City, Taiwan. The findings of the present study were as follows:1. The students' RAs achieved a moderate and positive correlation with their creative performance (CP), with increased correlation between RAs and the functionality and expressiveness constructs of CP and CP with the iconic representation (IR) construct of RAs.2. 3D-CAD evidently improved the students' CP, particularly their expressiveness and functionality.3. During 3D-CAD intervention, the students with low RAs performed similarly to those with high RAs in terms of novelty and expressiveness.

Design of novel polymeric adsorbents for metal ion removal from water using computer-aided molecular design

Heavy metals in drinking water act as contaminants that can cause serious health problems. These metal ions in drinking water are generally removed using cation exchange resins that are used as adsorbents. Generally, chelating resins with limited adsorption capacity are commercially available. Manufacturing novel resin polymers with enhanced adsorption capacity of metal ion requires ample experimental efforts that are expensive as well as time consuming. To overcome these difficulties, application of computer-aided molecular design (CAMD) will be an efficient way to develop novel chelating resin polymers. In this paper, CAMD based on group contribution method (GCM) has been used to design novel resins with enhanced adsorption capability of removing heavy metal ions from water. A polymer consists of multiple monomer units that repeat in a polymer chain. Each repeat unit of the polymer can be subdivided into different structural and functional groups. The adsorption mechanism of heavy metals on resin depends on the difference between activities in adsorbents and the bulk fluid phase. The contribution of the functional groups in the adsorption process is found by estimating the activity coefficient of heavy metal in the solid phase and bulk phase using a modified version of the UNIFAC GCM. The interaction parameters of the functional groups are first determined and then they are used in a combinatorial optimization method for CAMD of novel resin polymers. In this work, designs of novel resin polymers for the removal of Cu ions from drinking water are used as a case study. The proposed new polymer resin has an order of magnitude higher adsorption capacity compared to conventional resin used for the same purpose.

Ergonomics Perspective in Agricultural Research: A User-Centred Approach Using CAD and Digital Human Modeling (DHM) Technologies

Computer-aided Design (CAD) and Digital Human Modeling (DHM) (specialized CAD software for virtual human representation) technologies endow unique opportunities to incorporate human factors pro-actively in design development. Challenges of enhancing agricultural productivity through improvement of agricultural tools/machineries and better human–machine compatibility can be ensured by adoption of these modern technologies. Objectives of present work are to provide the detailed scenario of CAD and DHM applications in agricultural sector; and finding out means for wide adoption of these technologies for design and development of cost-effective, user-friendly, efficient and safe agricultural tools/equipment and operator’s workplace. Extensive literature review has been conducted for systematic segregation and representation of available information towards drawing inferences. Although applications of various CAD software have momentum in agricultural research particularly for design and manufacturing of agricultural equipment/machinery, use of DHM is still at its infancy in this sector. Current review discusses about reasons of less adoption of these technologies in agricultural sector and steps to be taken for their wide adoption. It also suggests possible future research directions to come up with better ergonomic design strategies for improvement of agricultural equipment/machines and workstations through application of CAD and DHM.

Static and dynamic modeling of organic thin-film transistors for circuit design

A new static and dynamic model for organic thin-film transistors (OTFTs) is proposed. The model incorporates a gate-voltage dependent mobility, drain/source contact series resistance, threshold voltage variation with bias and channel length, and drain induced barrier lowering effect. The model also takes into account all the operating regions and includes static and dynamic characteristics of OTFTs. It is developed using a physical basis where the model's parameters can easily be extracted from the experiment data. The model is suitable for computer aided design applications and has been verified by device simulations and measurements from both p-type and n-type OTFTs.

Geometric Range Search on Encrypted Spatial Data

Geometric range search is a fundamental primitive for spatial data analysis in SQL and NoSQL databases. It has extensive applications in location-based services, computer-aided design, and computational geometry. Due to the dramatic increase in data size, it is necessary for companies and organizations to outsource their spatial data sets to third-party cloud services (e.g., Amazon) in order to reduce storage and query processing costs, but, meanwhile, with the promise of no privacy leakage to the third party. Searchable encryption is a technique to perform meaningful queries on encrypted data without revealing privacy. However, geometric range search on spatial data has not been fully investigated nor supported by existing searchable encryption schemes. In this paper, we design a symmetric-key searchable encryption scheme that can support geometric range queries on encrypted spatial data. One of our major contributions is that our design is a general approach, which can support different types of geometric range queries. In other words, our design on encrypted data is independent from the shapes of geometric range queries. Moreover, we further extend our scheme with the additional use of tree structures to achieve search complexity that is faster than linear. We formally define and prove the security of our scheme with indistinguishability under selective chosen-plaintext attacks, and demonstrate the performance of our scheme with experiments in a real cloud platform (Amazon EC2).

Direct digital manufacturing of an accelerator pedal for a Formula Student racing car

Purpose This paper aims to focus on the design, analysis and additive manufacturing (AM) with two different technologies of an accelerator pedal for the Formula Student 2014 edition to reduce the weight of the original pedal in aluminium and maintain a reasonable level of performance. Design/methodology/approach The new and the original accelerator pedals were modelled in a computer-aided design application, and three finite element simulations were performed for each manufacturing technology to evaluate three different driving scenarios. Later on, two physical prototypes were manufactured using two AM technologies: poly-jet and fused deposition modelling (FDM). With these physical prototypes, static tests were carried out to verify the computational simulations and to determine the fracture load, while dynamic tests, based on an input signal from a real racing scenario, were performed to ensure their technical viability. Findings Simulations with poly-jet and FDM printing material show that the new design presents a maximum deformation of 4.8 and 4.09 mm, respectively, under a nominal load of 150N. The results of the static tests with the poly-jet physical prototype showed a maximum displacement of 4.05 mm under a nominal load of 150N, while the ultimate load before fracture was 450N. The FDM prototype reached 3.98 mm under 150N and the ultimate load was 350N. Dynamic tests showed that both pedals were able to withstand four Formula Student “Endurance” events without failure. Originality/value This paper states that AM approach is a feasible and economically affordable solution in comparison to exiting solutions with metallic alloys and composite materials when designing and manufacturing accelerator pedal arms for Formula Student competition cars. According to these results, the present research argues that, from a technical point of view, the AM pedals stand at a reasonable level of performance in displacements and stresses. This study suggests that AM pedals could be a viable option that must be considered in professional competitive automobiles.

A Randomized Incremental Algorithm for the Hausdorff Voronoi Diagram of Non-crossing Clusters

In the Hausdorff Voronoi diagram of a family of clusters of points in the plane, the distance between a point t and a cluster P is measured as the maximum distance between t and any point in P, and the diagram is defined in a nearest-neighbor sense for the input clusters. In this paper we consider non-crossing clusters in the plane, for which the combinatorial complexity of the Hausdorff Voronoi diagram is linear in the total number of points, n, on the convex hulls of all clusters. We present a randomized incremental construction, based on point location, that computes this diagram in expected $$O(n\log ^2{n})$$O(nlog2n) time and expected O(n) space. Our techniques efficiently handle non-standard characteristics of generalized Voronoi diagrams, such as sites of non-constant complexity, sites that are not enclosed in their Voronoi regions, and empty Voronoi regions. The diagram finds direct applications in VLSI computer-aided design.

Development of an efficient method of jamming prediction for designing locating systems in computer-aided fixture design

In the present study, the mathematical theory of jamming has been developed on the basis of minimum norm principle for workpieces with free-form surfaces. This has laid the basis of a new method proposed as an efficient means of jamming prediction, which is specifically helpful when designing the locating systems in computer-aided fixture design applications. The proposed method determines the contact states between the workpiece and the fixture and checks for the contact mode to predict possible jamming when loading a workpiece into the fixture, based on which the designer can modify the designed locating system in an attempt to avoid jamming. The presented model benefits from the lower computational complexity, quicker response, and more accurate results in comparison with the previous studies in jamming prediction processes. In addition, this method does not require the contact modes to be known beforehand. This is especially crucial at the early stages of the locating system design when the contact mode is not yet clear. Three case studies have been used for evaluating the capabilities of the suggested model, including peg-in-hole, block and palm, and a typical workpiece of 3D free-form model configuration. The results have also been compared with those of previous studies.