A Finite-Differences Derivative-Descent Approach for Estimating Form Error in Precision-Manufactured Parts

2005 ◽  
Vol 128 (1) ◽  
pp. 355-359 ◽  
Author(s):  
Abhijit Gosavi ◽  
Shantanu Phatakwala
Keyword(s):  
Objective Function ◽  
Computational Methods ◽  
Finite Differences ◽  
Analytical Methods ◽  
Critical Role ◽  
Computational Techniques ◽  
Computational Technique ◽  
Error Measurement ◽  
Form Error ◽  
Research Attention

Background: Form-error measurement is mandatory for the quality assurance of manufactured parts and plays a critical role in precision engineering. There is now a significant literature on analytical methods of form-error measurement, which either use mathematical properties of the relevant objective function or develop a surrogate for the objective function that is more suitable in optimization. On the other hand, computational or numerical methods, which only require the numeric values of the objective function, are less studied in the literature on form-error metrology. Method of Approach: In this paper, we develop a methodology based on the theory of finite-differences derivative descent, which is of a computational nature, for measuring form error in a wide spectrum of features, including straightness, flatness, circularity, sphericity, and cylindricity. For measuring form-error in cylindricity, we also develop a mathematical model that can be used suitably in any computational technique. A goal of this research is to critically evaluate the performance of two computational methods, namely finite-differences and Nelder-Mead, in form-error metrology. Results: Empirically, we find encouraging evidence with the finite-differences approach. Many of the data sets used in experimentation are from the literature. We show that the finite-differences approach outperforms the Nelder-Mead technique in sphericity and cylindricity. Conclusions: Our encouraging empirical evidence with computational methods (like finite differences) indicates that these methods may require closer research attention in the future as the need for more accurate methods increases. A general conclusion from our work is that when analytical methods are unavailable, computational techniques form an efficient route for solving these problems.

Computational Methods for Socio-Computer Interaction

2018 ◽  
Author(s):  
Wai-Tat Fu ◽  
Mingkun Gao ◽  
Hyo Jin Do
Keyword(s):  
Computational Methods ◽  
User Interfaces ◽  
Social Processes ◽  
Computational Techniques ◽  
Special Focus ◽  
Design Features ◽  
Social Phenomena ◽  
Online Social Media ◽  
Social Opinions ◽  
Computer Interaction

From the Arab Spring to presidential elections, various forms of online social media, forums, and networking platforms have been playing increasing significant roles in our societies. These emerging socio-computer interactions demand new methods of understanding how various design features of online tools may moderate the percolation of information and gradually shape social opinions, influence social choices, and moderate collective action. This chapter starts with a review of the literature on the different ways technologies impact social phenomena, with a special focus on theories that characterize how social processes are moderated by various design features of user interfaces. It then reviews different theory-based computational methods derived from these theories to study socio-computer interaction at various levels. Specific examples of computational techniques are reviewed to illustrate how they can be useful for influencing social processes for various purposes. The chapter ends with how future technologies should be designed to improve socio-computer interaction.

scholarly journals Computational-Driven Epitope Verification and Affinity Maturation of TLR4-Targeting Antibodies

2021 ◽  
Vol 22 (11) ◽  
pp. 5989
Author(s):  
Bilal Ahmad ◽  
Maria Batool ◽  
Moon Suk Kim ◽  
Sangdun Choi
Keyword(s):  
Rational Design ◽  
Structural Integrity ◽  
Critical Role ◽  
Autoimmune Encephalitis ◽  
Affinity Maturation ◽  
Antibody Binding ◽  
Computational Techniques ◽  
Multiple Strategies ◽  
Binding Epitope

Toll-like receptor (TLR) signaling plays a critical role in the induction and progression of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematous, experimental autoimmune encephalitis, type 1 diabetes mellitus and neurodegenerative diseases. Deciphering antigen recognition by antibodies provides insights and defines the mechanism of action into the progression of immune responses. Multiple strategies, including phage display and hybridoma technologies, have been used to enhance the affinity of antibodies for their respective epitopes. Here, we investigate the TLR4 antibody-binding epitope by computational-driven approach. We demonstrate that three important residues, i.e., Y328, N329, and K349 of TLR4 antibody binding epitope identified upon in silico mutagenesis, affect not only the interaction and binding affinity of antibody but also influence the structural integrity of TLR4. Furthermore, we predict a novel epitope at the TLR4-MD2 interface which can be targeted and explored for therapeutic antibodies and small molecules. This technique provides an in-depth insight into antibody–antigen interactions at the resolution and will be beneficial for the development of new monoclonal antibodies. Computational techniques, if coupled with experimental methods, will shorten the duration of rational design and development of antibody therapeutics.

Deformation-free form error measurement of thin, plane-parallel optics floated on a heavy liquid

2010 ◽  
Vol 49 (10) ◽  
pp. 1849 ◽  
Author(s):  
Jiyoung Chu ◽  
Ulf Griesmann ◽  
Quandou Wang ◽  
Johannes A. Soons ◽  
Eric C. Benck
Keyword(s):  
Heavy Liquid ◽  
Free Form ◽  
Error Measurement ◽  
Form Error ◽  
Plane Parallel

Semi-Elimination Methodology for Simulating High Flow Features in a Reservoir

2021 ◽  
Author(s):  
Yahan Yang ◽  
Ali Samii ◽  
Zhenlong Zhao ◽  
Guotong Ren
Keyword(s):  
High Flow ◽  
Small Cells ◽  
Computational Techniques ◽  
Computational Technique ◽  
System Of Equations ◽  
Time Step ◽  
Linear System Of Equations ◽  
Time Stepping ◽  
Model Complex ◽  
Upstream Weighting

Abstract Despite the rapid rise of computing power and advances in computational techniques in past decades, it is still challenging in reservoir simulation to model complex and detailed features that are represented by small cells with large permeability values, for example, fractures, multi-segment wells, etc. While those features may carry a large amount of flow and thus have a significant impact on the performance prediction, the combination of small volume and large permeability unfortunately leads to well-known time stepping and convergence difficulties during Newton iteration. We address this issue of high flow through small cells by developing a new semi-elimination computational technique. At the beginning of simulation, we construct a set of pressure basis which is a mapping from pressures at surrounding cells in the bulk of reservoir to pressures at those small cells. Next, we start the time-stepping scheme. For each time step or iteration within a time step, small cells are first employed to provide an accurate computation of flow rates and derivatives using upstream weighting and a flow partitioning scheme. Afterwards, small cells are eliminated and a linear system of equations is assembled and solved involving only bulk cells. This semi-elimination technique allows us to fundamentally avoid the drawbacks caused by including small cells in the global system of equations, while capturing their effect on the flow of hydrocarbon in the reservoir. One of the advantages of the proposed techniques over other existing methods is that it is fully implicit and preserves upstream weighting and compositions of the flow field even after small cells are eliminated, which enhances numerical stability and accuracy of simulation results. Application of this technique to several synthetic and field models demonstrates significant performance and accuracy improvement over standard approaches. This method thus offers a practical way to model complex and dynamic flow behaviors in important features without incurring penalties in speed and robustness of the simulation.

Computational Methods in Environmental and Resource Economics

2019 ◽  
Vol 11 (1) ◽  
pp. 59-82 ◽  
Author(s):  
Yongyang Cai
Keyword(s):  
Computational Methods ◽  
Real Option ◽  
Resource Economics ◽  
Bilevel Optimization ◽  
Curse Of Dimensionality ◽  
Computational Method ◽  
Computational Techniques ◽  
Deterministic Models ◽  
Environmental And Resource Economics ◽  
Dynamic Stochastic

Computational methods are required to solve problems without closed-form solutions in environmental and resource economics. Efficiency, stability, and accuracy are key elements for computational methods. This review discusses state-of-the-art computational methods applied in environmental and resource economics, including optimal control methods for deterministic models, advances in value function iteration and time iteration for general dynamic stochastic problems, nonlinear certainty equivalent approximation, robust decision making, real option analysis, bilevel optimization, solution methods for continuous time problems, and so on. This review also clarifies the so-called curse of dimensionality, and discusses some computational techniques such as approximation methods without the curse of dimensionality and time-dependent approximation domains. Many existing economic models use simplifying and/or unrealistic assumptions with an excuse of computational feasibility, but these assumptions might be able to be relaxed if we choose an efficient computational method discussed in this review.

The effect of CSR commitment on firms’ level of internationalization

2019 ◽  
Vol 16 (8) ◽  
pp. 1415-1432
Author(s):  
Morteza Khojastehpour ◽  
Md Abu Saleh
Keyword(s):  
Host Country ◽  
Critical Role ◽  
Short Term ◽  
Research Attention ◽  
Content Type ◽  
General Terms ◽  
Regulatory Quality ◽  
Corporate Social ◽  
The Relationship

Purpose Corporate social responsibility (CSR) has received considerable research attention globally over the past decade. Although a growing number of prior studies have investigated the various dimensions of CSR in general terms, few studies have investigated the critical role that CSR can play in the internationalization process of firms. Design/methodology/approach Using S&P 500 companies during 2004-2014, the authors found that the level of CSR commitment raises the level of reliability of firm and allows further international penetration. Moreover, better regulatory quality of host country is at actual support of internationalization only when considering the short term. Findings Better regulatory quality of host country is at actual support of internationalization only when considering the short term. Originality/value The authors build on internationalization theory and CSR and examine the relationship between firms’ level of internationalization and CSR commitment.

Using Transfer Matrices for Parametric System Forced Response

1987 ◽  
Vol 109 (4) ◽  
pp. 356-360 ◽  
Author(s):  
J. W. David ◽  
L. D. Mitchell ◽  
J. W. Daws
Keyword(s):  
Harmonic Balance ◽  
Forced Response ◽  
Computational Techniques ◽  
Computational Technique ◽  
Transfer Matrices ◽  
Frequency Branch ◽  
Balance Technique ◽  
Systems Analysts ◽  
The Many ◽  
Harmonic Balance Technique

For many years, engineers and scientists have sought to deal with the many phenomena exhibiting parametric characteristics. While many approximate techniques are available for the analysis of such systems, the harmonic balance technique can be used to accurately model the response of systems where the coefficient variation is large. Also, in analyzing complex physical systems, analysts have sought to develop efficient computational techniques that are sufficiently general for the analysis of arbitrary systems. In this paper, it is shown that combining the harmonic balance technique with transfer matrices produces an efficient computational technique for the analysis of parametric systems where the coefficient variations can be large. The technique is demonstrated by considering a single-degree-of-freedom system with time varying stiffness. The harmonic balance technique is used to frequency-branch the transfer matrices, thus allowing multifrequency response calculations to be done simultaneously. The results are compared with direct numerical integrations of the equations. Lastly, this technique is applied to a simple gear coupled rotor system to demonstrate the application of this technique to large order systems of more engineering relevance.

scholarly journals Computational Methods for the Identification of Molecular Targets of Toxic Food Additives. Butylated Hydroxytoluene as a Case Study

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2229 ◽  
Author(s):  
Valentina Tortosa ◽  
Valentina Pietropaolo ◽  
Valentina Brandi ◽  
Gabriele Macari ◽  
Andrea Pasquadibisceglie ◽  
...  
Keyword(s):  
Computational Methods ◽  
Food Additives ◽  
Daily Intake ◽  
Experimental Studies ◽  
Butylated Hydroxytoluene ◽  
Computational Techniques ◽  
Toxicological Effects ◽  
Ligand Interactions ◽  
Toxic Food

Butylated hydroxytoluene (BHT) is one of the most commonly used synthetic antioxidants in food, cosmetic, pharmaceutical and petrochemical products. BHT is considered safe for human health; however, its widespread use together with the potential toxicological effects have increased consumers concern about the use of this synthetic food additive. In addition, the estimated daily intake of BHT has been demonstrated to exceed the recommended acceptable threshold. In the present work, using BHT as a case study, the usefulness of computational techniques, such as reverse screening and molecular docking, in identifying protein–ligand interactions of food additives at the bases of their toxicological effects has been probed. The computational methods here employed have been useful for the identification of several potential unknown targets of BHT, suggesting a possible explanation for its toxic effects. In silico analyses can be employed to identify new macromolecular targets of synthetic food additives and to explore their functional mechanisms or side effects. Noteworthy, this could be important for the cases in which there is an evident lack of experimental studies, as is the case for BHT.

scholarly journals Combining Experimental Data and Computational Methods for the Non-Computer Specialist

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4783
Author(s):  
Reinier Cárdenas ◽  
Javier Martínez-Seoane ◽  
Carlos Amero
Keyword(s):  
Experimental Data ◽  
Molecular Mechanism ◽  
Computational Methods ◽  
Dynamic Systems ◽  
Experimental Methods ◽  
Computational Techniques ◽  
Biological Macromolecules ◽  
Basic Principles ◽  
Structural Interpretation

Experimental methods are indispensable for the study of the function of biological macromolecules, not just as static structures, but as dynamic systems that change conformation, bind partners, perform reactions, and respond to different stimulus. However, providing a detailed structural interpretation of the results is often a very challenging task. While experimental and computational methods are often considered as two different and separate approaches, the power and utility of combining both is undeniable. The integration of the experimental data with computational techniques can assist and enrich the interpretation, providing new detailed molecular understanding of the systems. Here, we briefly describe the basic principles of how experimental data can be combined with computational methods to obtain insights into the molecular mechanism and expand the interpretation through the generation of detailed models.

Offset Surface Generation and Contouring in Computer-Aided Design

1987 ◽  
Vol 109 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Y. J. Chen ◽  
B. Ravani
Keyword(s):  
Computer Aided Design ◽  
Numerical Control ◽  
Surface Generation ◽  
Computational Techniques ◽  
Computational Technique ◽  
Contour Lines ◽  
Computer Aided ◽  
Offset Surfaces ◽  
Aided Design ◽  
Offset Surface

Two computational techniques are presented for Computer-Aided Design (CAD) and Machining (CAM) of parametrically defined surfaces. One technique deals with construction of offset surfaces. An algorithm is presented that would allow detection and removal of the closed loop on the offset surface due to its self-intersection. The second computational technique presented deals with contouring of parametric surfaces. The technique presented allows for optimal generation of planar contour lines. The results are applied to Numerical Control (NC) machining of surfaces.

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