Concurrent optimization of airframe and engine design parameters

An integrated system for the multidisciplinary analysis and optimization of airframe and propulsion design parameters is being developed. This system is known as IPAS, the Integrated Propulsion/Airframe Analysis System. The traditional method of analysis is one in which the propulsion system analysis is loosely coupled to the overall mission performance analysis. This results in a time consuming iterative process. First, the engine is designed and analyzed. Then, the results from this analysis are used in a mission analysis to determine the overall aircraft performance. The results from the mission analysis are used as a guide as the engine is redesigned and the entire process repeated. In IPAS, the propulsion system, airframe, and mission are closely coupled. The propulsion system analysis code is directly integrated into the mission analysis code. This allows the propulsion design parameters to be optimized along with the airframe and mission design parameters, significantly reducing the time required to obtain an optimized solution

Management Research on Multinational Corporations: A Methodological Critique

In the context of burgeoning research on multinational corporations (MNCs), this paper addresses the issue of the representativeness of databases of MNCs in Ireland. It identifies some important deficiencies in existing databases much used by scholars in the field. Drawing on the international literature, it finds that this problem also characterises research on MNCs in many other countries. In the Irish context, we find that the extant empirical research has generally excluded two key categories of MNCs, namely, (a) foreign MNCs which are not grant-aided by the main industrial promotions agencies and (b) Irish-owned MNCs. The paper outlines our experience in identifying and addressing these deficiencies and describes the methods that might be employed in more precisely defining the MNC population in Ireland. More generally the paper reviews some of the issues and obstacles confronting scholars investigating the MNC sector in Ireland and abroad.

Subnational location capital: the role of subnational institutional actors and socio-spatial factors on firm location

peer-reviewedFirms do not simply locate, but rather seek to accrue location‐based advantages such as knowledge, market insidership and resource utilization. Adopting the lens of social capital, this paper explores how subnational institutional actors facilitate location capital for firms. Using qualitative case study analysis of six multinational companies (MNCs), we highlight the important role of subnational institutional actors in fostering three dimensions of subnational location capital – structural, relational and cognitive. We show that subnational location capital, defined as the economic and social assets accessible through relationships within a subnational location, enable firms to derive advantages via subnational engagement. These findings contribute to the growing literature on the dynamic interaction of firms with subnational location, particularly the nuanced role of subnational institutional actors with MNCs.peer-reviewe

Global standardization or national differentiation of HRM practices in multinational companies? A comparison of multinationals in five countries

Drawing on a dataset constructed from a parallel series of nationally representative surveys of multinational companies (MNCs), we compare the performance management (PM) practices of MNCs in the UK, Ireland, Canada, Spain, Denmark and Norway. In each country we analyze data relating to MNCs from that country and of the foreign affiliates of US MNCs. We argue that there is evidence of standardization in the nature of practices across countries, particularly evident in the analysis of US MNCs. Standardization of practices among MNCs is also evident in the rather limited variation in practices between US and indigenous MNCs within each country. Moreover, even where there is evidence of variation across and within countries, this cannot be fully explained by adaptation to local institutional constraints but rather can be seen as the product of how distinct national contexts can promote the take-up of practices.The project was supported by a number of funding bodies and research centres: Canada’s Social Sciences and Humanities Research Council (the SSHRC Major Collaborative Research Initiatives, Initiatives on the New Economy and International Opportunities Fund), the Fonds québécois de recherché sur la société et la culture (Équipes and Regroupements stratégiques), the Canada Research Chair on Globalization and Work, the Interuniversity Research Centre on Globalization and Work (CRIMT); Ireland’s Labour Relations Commission, the Irish Research Council for the Humanities and Social Sciences, the University of Limerick Research Office; Spain’s Ministries of Education and Science (Ref. SEJ2007-03096, Award 01/0010/2006) and Science and Innovation (Ref: ECO2009-10287), the Directorate-General for Scientific Investigation of the Madrid region (Award 06/0009/2000), the BBVA Foundation (Ref. 216/06), the Autonomous University of Madrid/Banco Santander (Ref: CEAL-AL/2011-28), IESE Business School; the UK’s Economic and Social Research Council (Awards RES-000-23-0305 and RES-062-23-2080); Danish Research Council for Independent Research (FSE) (Ref. 275-09-0146); and the European Commission’s International Research Staff Exchange Scheme (FP7 IRSES-GA-2008-230854 – INTREPID

Commercial Modular Aero-Propulsion System Simulation 40k

The Commercial Modular Aero-Propulsion System Simulation 40k (CMAPSS40k) software package is a nonlinear dynamic simulation of a 40,000-pound (approximately equals 178-kN) thrust class commercial turbofan engine, written in the MATLAB/Simulink environment. The model has been tuned to capture the behavior of flight test data, and is capable of running at any point in the flight envelope [up to 40,000 ft (approximately equals 12,200 m) and Mach 0.8]. In addition to the open-loop engine, the simulation includes a controller whose architecture is representative of that found in industry. C-MAPSS40k fills the need for an easy-to-use, realistic, transient simulation of a medium-size commercial turbofan engine with a representative controller. It is a detailed component level model (CLM) written in the industry-standard graphical MATLAB/Simulink environment to allow for easy modification and portability. At the time of this reporting, no other such model exists in the public domain

Development of a Twin-Spool Turbofan Engine Simulation Using the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS)

The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3% of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies

A High-Fidelity Simulation of a Generic Commercial Aircraft Engine and Controller

A new high-fidelity simulation of a generic 40,000 lb thrust class commercial turbofan engine with a representative controller, known as CMAPSS40k, has been developed. Based on dynamic flight test data of a highly instrumented engine and previous engine simulations developed at NASA Glenn Research Center, this non-proprietary simulation was created especially for use in the development of new engine control strategies. C-MAPSS40k is a highly detailed, component-level engine model written in MATLAB/Simulink (The MathWorks, Inc.). Because the model is built in Simulink, users have the ability to use any of the MATLAB tools for analysis and control system design. The engine components are modeled in C-code, which is then compiled to allow faster-than-real-time execution. The engine controller is based on common industry architecture and techniques to produce realistic closed-loop transient responses while ensuring that no safety or operability limits are violated. A significant feature not found in other non-proprietary models is the inclusion of transient stall margin debits. These debits provide an accurate accounting of the compressor surge margin, which is critical in the design of an engine controller. This paper discusses the development, characteristics, and capabilities of the C-MAPSS40k simulatio

Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) User's Guide

The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) software package is an open source, MATLABSimulink toolbox (plug in) that can be used by industry professionals and academics for the development of thermodynamic and controls simulations

Propulsion System Simulation Using the Toolbox for the Modeling and Analysis of Thermodynamic System T-MATS

A simulation toolbox has been developed for the creation of both steady-state and dynamic thermodynamic software models. This paper describes the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS), which combines generic thermodynamic and controls modeling libraries with a numerical iterative solver to create a framework for the development of thermodynamic system simulations, such as gas turbine engines. The objective of this paper is to present an overview of T-MATS, the theory used in the creation of the module sets, and a possible propulsion simulation architecture. A model comparison was conducted by matching steady-state performance results from a T-MATS developed gas turbine simulation to a well-documented steady-state simulation. Transient modeling capabilities are then demonstrated when the steady-state T-MATS model is updated to run dynamically

Cantera Integration with the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)

NASA Glenn Research Center (GRC) has recently developed a software package for modeling generic thermodynamic systems called the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink (The MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The current version of T-MATS (v1.0.1) uses tabular data for providing information about a specific mixture of air, water (humidity), and hydrocarbon fuel in calculations of thermodynamic properties. The capabilities of T-MATS can be expanded by integrating it with the Cantera thermodynamic package. Cantera is an object-oriented analysis package that calculates thermodynamic solutions for any mixture defined by the user. Integration of Cantera with T-MATS extends the range of systems that may be modeled using the toolbox. In addition, the library of elements released with Cantera were developed using MATLAB native M-files, allowing for quicker prototyping of elements. This paper discusses how the new Cantera-based elements are created and provides examples for using T-MATS integrated with Cantera