scholarly journals MULTIDIMENSIONAL TRANSITIONAL DYNAMICS: A SIMPLE NUMERICAL PROCEDURE

2008 ◽  
Vol 12 (3) ◽  
pp. 301-319 ◽  
Author(s):  
TIMO TRIMBORN ◽  
KARL-JOSEF KOCH ◽  
THOMAS M. STEGER
Keyword(s):  
Growth Models ◽  
Numerical Procedure ◽  
Monetary Economics ◽  
Transition Process ◽  
Infinite Time ◽  
Natural Manner ◽  
Relaxation Algorithm ◽  
Wide Range ◽  
User Friendly ◽  
Illustrative Application

We propose the relaxation algorithm as a simple and powerful method for determining the transition process in growth models numerically. This method has a number of important advantages: (1) It can easily deal with a wide range of dynamic systems including stiff differential equations and systems giving rise to a continuum of stationary equilibria. (2) The application of the procedure is fairly user-friendly. The only input required consists of the dynamic system. (3) The variant of the relaxation algorithm we propose exploits in a natural manner the infinite time horizon, which usually underlies optimal control problems in economics. As an illustrative application, we compute the transition process of the models of Jones [Jones, C.I. (1995) R&D-based models of economic growth. Journal of Political Economy 103 (3), 759–784] and Lucas [Lucas, R.E., Jr. (1988) On the mechanics of economic development. Journal of Monetary Economics 22, 3–42].

Measurement of Unsteady Flow in Pump-Turbine for Hydropower Using PIV Method

2009 ◽  
Author(s):  
Nobuhiko Fukuda ◽  
Satoshi Someya ◽  
Koji Okamoto
Keyword(s):  
Rotational Speed ◽  
Velocity Measurement ◽  
Numerical Procedure ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
High Time ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Runner Blade ◽  
Wide Range

It is thought that the pressure fluctuation can occur due to the interaction between flow through guide vanes and flow into runner blades, resulting in a vibration of turbine and a blade cracking, in a hydraulic turbine operated in a wide range for flexible power demand. High accurate velocity measurement with high time/spatial resolution can help to clarify the mechanism of the interaction and to provide good experimental data for the validation of numerical procedure. So the aim of present study is to estimate the unstable velocity field quantitatively in the area between guide vanes and runner blades, using high time-resolved particle image velocimetry (PIV). Two types of velocity measurements were carried out, i.e., phase-locked measurement and high time sequential velocity measurement, in a pump-turbine model with 20 guide vanes and 6 runner blades. The characteristic of the flow field varied corresponding to the operating conditions such as flow rate and rotational speed. Opening angles of guide vanes were kept uniform. A clockwise vortex was generated at inside of the runner blade under smaller rotational speed. A counterclockwise vortex was separated at the backside of the runner blade under higher rotational speed. At any operating conditions, the velocity between guide vanes and runner blades oscillated periodically at the blade passing frequency.

Thermoacoustic Stability Analysis of a Full-Annular Lean Combustor for Heavy-Duty Applications

2021 ◽  
Author(s):  
Daniele Pampaloni ◽  
Antonio Andreini ◽  
Alessandro Marini ◽  
Giovanni Riccio ◽  
Gianni Ceccherini
Keyword(s):  
Stability Analysis ◽  
Gas Turbine ◽  
Flame Temperature ◽  
Numerical Procedure ◽  
Pollutant Emissions ◽  
Computational Time ◽  
Heavy Duty ◽  
Operational Parameters ◽  
3D Fem ◽  
Wide Range

Abstract Thermoacoustic characterization of gas turbine combustion systems is of primary importance for successful development of gas turbine technology, to meet the stringent targets on pollutant emissions. In this context, it becomes more and more necessary to develop reliable tools to be used in the industrial design process. The dynamics of a lean-premixed full-annular combustor for heavy-duty applications has been numerically studied in this work. The well-established CFD-SI method has been used to investigate the flame response varying operational parameters such as the flame temperature (global equivalence ratio) and the fuel split between premixed and pilot fuel injections: such a wide range experimental characterization represents an opportunity to validate the employed numerical methods and to give a deeper insight into the flame dynamics. URANS simulations have been performed, due to their affordable computational costs from the industrial perspective, after validating their accuracy through the comparison against LES results. Furthermore, an approach where the pilot and the premixed flame responses are analyzed separately is proposed, exploiting the independence of their evolution. The calculated FTFs have been implemented in a 3D FEM model of the chamber, in order to perform linear stability analysis and to validate the numerical approach. A boundary condition for rotational periodicity based on Bloch-Wave theory has been implemented into the Helmholtz solver and validated against full-annular chamber simulations, allowing a significant reduction in computational time. The reliability of the numerical procedure has been assessed through the comparison against full-annular experimental results.

Elastohydrodynamic Lubrication of Soft-Layered Solids at Elliptical Contacts: Part 1: Elasticity Analysis

1994 ◽  
Vol 208 (1) ◽  
pp. 31-41 ◽  
Author(s):  
J Q Yao ◽  
D Dowson
Keyword(s):  
Aspect Ratio ◽  
Surface Deformation ◽  
Applied Pressure ◽  
Numerical Procedure ◽  
Elastohydrodynamic Lubrication ◽  
Thin Layers ◽  
Elasticity Analysis ◽  
Synovial Joint ◽  
Wide Range ◽  
Non Linear System

In this two-part paper we consider the elastohydrodynamic lubrication (EHL) of soft-layered solids representing elliptical contacts. The problem has not previously attracted much attention, partly due to the lack of an effective numerical procedure to solve the coupled non-linear system of equations, but it is essential to the proper design of bearings with soft elastomeric liners and the full understanding of synovial joint lubrication. In Part 1, the elasticity analysis for the surface deformation of a low elastic modulus layer on a hard-backing half-space under various forms of normal loadings is considered, by means of both the rigorous Hankel transform method and various simplifications. For layers of compressible materials (v ≤ 0.4), a generalized foundation model described by a second-order differential equation is proposed to represent the relationship between the surface deformation and the applied pressure. The empirical equation developed in this study is valid for a very wide range of the aspect ratio of the contact and provides an alternative way of modelling the elastic deformation without recourse to the often tedious integration in the numerical analysis of the EHL problem. The simplest form (constrained column model) of the equation, where the surface deformation is directly proportional to the local applied pressure, was found to be reasonably accurate for compressible thin layers (the aspect ratio 2b/ht ≥ 5 and Poisson's ratio v ≤ 0.4).

The Intelligent Design of the Gear Reducer

2012 ◽  
Vol 522 ◽  
pp. 823-827
Author(s):  
Jian Jiang Fang ◽  
Wen Jun Qi
Keyword(s):  
Intelligent Design ◽  
Object Oriented ◽  
Data Access ◽  
Mechanical Transmission ◽  
Design Efficiency ◽  
Integrated Technology ◽  
Gear Drive ◽  
Object Oriented Technology ◽  
Wide Range ◽  
User Friendly

The gear drive is the wide range of applications and is particularly important as a form of mechanical transmission, but the design process requires large amounts of data access and computation. In the paper, computer integrated technology and object-oriented technology is used to research and develop the intelligent design of Straight gear reducer system with user-friendly interactive platform, easy to use, high design efficiency and reliable data.

Aeroelastic Optimization of an Industrial Compressor Rotor Blade Geometry

2018 ◽  
Author(s):  
Federico Vanti ◽  
Lorenzo Pinelli ◽  
Andrea Arnone ◽  
Andrea Schneider ◽  
Pio Astrua ◽  
...  
Keyword(s):  
Numerical Procedure ◽  
Optimization Procedure ◽  
Multidisciplinary Optimization ◽  
Optimization Process ◽  
Geometrical Parameters ◽  
Aerodynamic Optimization ◽  
Compressor Rotor ◽  
Wide Range ◽  
Automatic Optimization ◽  
Blade Geometry

This paper describes a multidisciplinary optimization procedure applied to a compressor blade-row. The numerical procedure takes into account both aerodynamic (efficiency) and aeromechanic (flutter-free design) goals nowadays required by turbo-machinery industries and is applied to a low pressure compressor rotor geometry provided by Ansaldo Energia S.p.A.. Some typical geometrical parameters have been selected and modified during the automatic optimization process in order to generate an optimum geometry with an improved efficiency and, at the same time, a safety flutter margin. This new automatic optimization procedure, which now includes a flutter stability assessment, is an extension of an existing aerodynamic optimization process, which randomly perturbs a starting 3D blade geometry inside a constrained range of values, build the fluid mesh and run the CFD steady analysis. The new implementation provides the self-building of the solid mesh, the FEM analysis and finally the unsteady uncoupled aeroelastic analysis to assess the flutter occurrence. After simulating a wide range of geometries, a database with all the constraint parameters and objective functions is obtained and then used to train a neural network algorithm. Once the ANN validation error is converged, an optimization strategy is used to build the Pareto front and to provide a set of optimum geometries redesigning the original compressor rotor. The aim of this paper is to show the opportunity to also take into account the aeroelastic issues in optimization processes.

scholarly journals SorghumBase: a web-based portal for sorghum genetic information and community advancement

Planta ◽  
2022 ◽  
Vol 255 (2) ◽  
Author(s):  
Nicholas Gladman ◽  
Andrew Olson ◽  
Sharon Wei ◽  
Kapeel Chougule ◽  
Zhenyuan Lu ◽  
...  
Keyword(s):  
Resource Sharing ◽  
Content Management ◽  
Research Community ◽  
Data Types ◽  
Training Materials ◽  
Wide Range ◽  
Variant Information ◽  
Data Collation ◽  
Genome Assemblies ◽  
User Friendly

Abstract Main conclusion SorghumBase provides a community portal that integrates genetic, genomic, and breeding resources for sorghum germplasm improvement. Abstract Public research and development in agriculture rely on proper data and resource sharing within stakeholder communities. For plant breeders, agronomists, molecular biologists, geneticists, and bioinformaticians, centralizing desirable data into a user-friendly hub for crop systems is essential for successful collaborations and breakthroughs in germplasm development. Here, we present the SorghumBase web portal (https://www.sorghumbase.org), a resource for the sorghum research community. SorghumBase hosts a wide range of sorghum genomic information in a modular framework, built with open-source software, to provide a sustainable platform. This initial release of SorghumBase includes: (1) five sorghum reference genome assemblies in a pan-genome browser; (2) genetic variant information for natural diversity panels and ethyl methanesulfonate (EMS)-induced mutant populations; (3) search interface and integrated views of various data types; (4) links supporting interconnectivity with other repositories including genebank, QTL, and gene expression databases; and (5) a content management system to support access to community news and training materials. SorghumBase offers sorghum investigators improved data collation and access that will facilitate the growth of a robust research community to support genomics-assisted breeding.

scholarly journals Empirical Research of the ISO 9001:2015 Transition Process in Portugal: Motivations, Benefits, and Success Factors

2018 ◽  
Vol 22 (2) ◽  
pp. 16 ◽  
Author(s):  
Luis Miguel Fonseca ◽  
José Pedro Domingues
Keyword(s):  
Success Factors ◽  
Transition Period ◽  
Transition Process ◽  
Iso 9001 ◽  
Useful Knowledge ◽  
Stakeholder Identification ◽  
Bias Risk ◽  
Wide Range ◽  
The Status ◽  
Research Gap

<p><strong>Purpose:</strong> With the transition period for ISO 9001 certified organisations to migrate to the 2015 edition ending 15th September 2018, this investigation aims to evaluate the status of ISO 9001:2015 transition process and provide useful knowledge on the corresponding motivations, benefits, and success factors.</p><p><strong>Methodology/Approach:</strong> An empirical study of more than 300 Portuguese organisations ISO 9001 certified, or in certification process, encompassing a wide range of activities sectors, was carried out.</p><p><strong>Findings:</strong> As of May 2017, 19% of the respondents already have ISO 9001:2015 certification and all the remaining one’s plan to complete the process in time. The principal reported benefits are risk-based thinking, mapping of the organisational context, and stakeholder identification. Simultaneously those were the issues that required more attention and effort to be mastered and implemented. Additionally, there is evidence that ISO 9001:2015 enhances both internal and external organisational issues and generates benefits for all the researched dimensions. Based on the respondents’ responses, organisations who claimed that external motivations were the primary drivers to ISO 9001:2015 implementation systematically rate higher all the benefits when compared with the rating ascribed by those organisations who claimed internal motivations. Moreover, it is possible to conclude that the perceived benefits from ISO 9001:2015 implementation and certification seem to be strongly influenced by two primary dimensions: the (smaller) organisation size and the (lesser) international presence.</p><p><strong>Research Limitation/implication:</strong> Due to ISO 9001:2015 novelty, the results of this investigation should be subject to future confirmation and replicated in other countries to allow a generalisation of the conclusions. Since the survey is based on the perceptions of the organisation’s Managers, there is a potential response bias risk that should be acknowledged.</p><p><strong>Originality/Value of paper:</strong> With more than 1.2 million ISO 9001 certified organisation worldwide, this a highly relevant issue both for organisations, practitioners and academics. Due to ISO 9001:2015 novelty, this investigation aims to fill this research gap.</p>

Users’ Attitudes towards Institutional Repository in Jadavpur University: A Critical Study

2012 ◽  
Vol 1 (2) ◽  
pp. 45-52
Author(s):  
Sambhu Nath Halder ◽  
Suvra Chandra
Keyword(s):  
Potential Role ◽  
Point Of View ◽  
Academic Institution ◽  
Critical Study ◽  
Institutional Repository ◽  
Digital Environment ◽  
Institutional Repositories ◽  
Wide Range ◽  
User Friendly

This paper examines the user-aware of institutional repositories in Jadavpur University. The main objective of this study is to investigate the awareness of Institutional Repository (IR) in an academic institution and different aspects associated with it, such as, software, sources for user’s awareness, motivators for developing a repository, demand of the users in changing paradigms from traditional to digital environment, etc. In the present days, libraries are also adopting the latest technologies to provide best possible services in user friendly form. This paper also describes the potential role of institutional repositories and its easiness and simplicity of use are attracting more patrons in the use of institutional repositories. Only a wide range of user awareness is needed for proper usage of its beauty. Entirely this paper is based on a critical study, which measures the utility of institutional repositories in users’ point of view.

Bring Out Your Data

2012 ◽  
pp. 126-145
Author(s):  
Thomas E. Grissom ◽  
Andrew DuKatz ◽  
Hubert A. Kordylewski ◽  
Richard P. Dutton
Keyword(s):  
Cost Effective ◽  
Regulatory Oversight ◽  
Measurement Quality ◽  
Related Data ◽  
Healthcare Data ◽  
Effective Manner ◽  
Wide Range ◽  
Automated Process ◽  
User Friendly ◽  
Quality Institute

Recent healthcare legislation, financial pressures, and regulatory oversight have increased the need to create improved mechanisms for performance measurement, quality management tracking, and outcomes-based research. The Anesthesia Quality Institute (AQI) has established the National Anesthesia Clinical Outcomes Registry (NACOR) to support these requirements for a wide-range of customers including individual anesthesiologists, anesthesia practices, hospitals, and credentialing agencies. Concurrently, the availability of increased digital sources of healthcare data make it possible to capture massive quantities of data in a more efficient and cost-effective manner than ever before. With NACOR, AQI has established a user-friendly, automated process to effectively and efficiently collect a wide-range of anesthesia-related data directly from anesthesia practices. This review will examine the issues guiding the evolution of NACOR as well as some potential pitfalls in its growth and usage.

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