Trade-offs and performance limitations in mechatronic systems: a case study

2004 ◽  
Vol 28 (2) ◽  
pp. 181-192 ◽  
Author(s):  
Osamah M. El Rifai ◽  
Kamal Youcef-Toumi
Keyword(s):  
Mechatronic Systems ◽  
Trade Offs ◽  
Performance Limitations ◽  
And Performance

Preliminary Design and Performance of Counter Rotating Turbines for Open Rotors: Part II — 0-D Methodology and Case Study for a 160 PAX Aircraft

2016 ◽  
Author(s):  
Pablo Bellocq ◽  
Inaki Garmendia ◽  
Jordane Legrand ◽  
Vishal Sethi
Keyword(s):  
Design Methodology ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Preliminary Design ◽  
Regulatory Constraints ◽  
Trade Offs ◽  
And Performance ◽  
The Impact

Direct Drive Open Rotors (DDORs) have the potential to significantly reduce fuel consumption and emissions relative to conventional turbofans. However, this engine architecture presents many design and operational challenges both at engine and aircraft level. At preliminary design stages, a broad design space exploration is required to identify potential optimum design regions and to understand the main trade offs of this novel engine architecture. These assessments may also aid the development process when compromises need to be performed as a consequence of design, operational or regulatory constraints. Design space exploration assessments are done with 0-D or 1-D models for computational purposes. These simplified 0-D and 1-D models have to capture the impact of the independent variation of the main design and control variables of the engine. Historically, it appears that for preliminary design studies of DDORs, Counter Rotating Turbines (CRTs) have been modelled as conventional turbines and therefore it was not possible to assess the impact of the variation of the number of stages (Nb) of the CRT and rotational speed of the propellers. Additionally, no preliminary design methodology for CRTs was found in the public domain. Part I of this two-part publication proposes a 1-D preliminary design methodology for DDOR CRTs which allows an independent definition of both parts of the CRT. A method for calculating the off-design performance of a known CRT design is also described. In Part II, a 0-D design point efficiency calculation for CRTs is proposed and verified with the 1-D methods. The 1-D and 0-D CRT models were used in an engine control and design space exploration case study of a DDOR with a 4.26m diameter an 10% clipped propeller for a 160 PAX aircraft. For this application: • the design and performance of a 20 stage CRT rotating at 860 rpm (both drums) obtained with the 1-D methods is presented. • differently from geared open rotors, negligible cruise fuel savings can be achieved by an advanced propeller control. • for rotational speeds between 750 and 880 rpm (relatively low speeds for reduced noise), 22 and 20 stages CRTs are required. • engine weight can be kept constant for different design rotational speeds by using the minimum required Nb. • for any target engine weight, TOC and cruise SFC are reduced by reducing the rotational speeds and increasing Nb (also favourable for reducing CRP noise). However additional CRT stages increase engine drag, mechanical complexity and cost.

Migrating a Legacy Web-Based Document-Analysis Application to Hadoop and HBase

2012 ◽  
pp. 226-247 ◽  
Author(s):  
Himanshu Vashishtha ◽  
Michael Smit ◽  
Eleni Stroulia
Keyword(s):  
Development Activity ◽  
Web Based ◽  
Computing Platform ◽  
Trade Offs ◽  
Service Oriented ◽  
Analysis Application ◽  
Software Platforms ◽  
And Performance ◽  
Web Based System

Migrating a legacy application to a more modern computing platform is a recurring software-development activity. This chapter describes the authors’ experience with a contemporary rendition of this activity, migrating a Web-based system to a service-oriented application on two different cloud software platforms, Hadoop and HBase. Using the case study as a running example, they review the information needed for a successful migration and examine the trade-offs between development/re-design effort and performance/scalability improvements. The two levels of re-design, towards Hadoop and HBase, require notably different levels of effort, and as the authors found through exercising the migrated applications, they achieve different benefits. The authors found that both redesigns led to substantial benefit in performance improvement, and that expending the additional effort required by the more complex migration resulted in notable improvements in the ability to leverage the benefits of the platform.

An Optimization Method for the Concept Design of Semi-Submersible Offshore Accommodation Units

2018 ◽  
Author(s):  
Thiago S. Hallak ◽  
Manuel Ventura ◽  
C. Guedes Soares
Keyword(s):  
Genetic Algorithm ◽  
Stability Analysis ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Concept Design ◽  
Final Solution ◽  
Trade Offs ◽  
And Performance ◽  
Optimized Geometries

A methodology for the initial dimensioning and evaluation of semi-submersible offshore accommodation units by use of a novel optimization procedure is presented. The method developed has two main steps. First, the optimization procedure itself, in which a set of different configurations is considered and one by one optimized following a genetic algorithm in terms of cost estimates, whereas several other characteristics of the units are evaluated according to an embedded synthesis model. Second, the set of optimized geometries are run in commercial software for accurate seakeeping and stability analysis, where requirements’ compliance are checked. The final solution may then be chosen considering the trade-offs between cost and performance. In the last section of this paper, a case study is presented and the results obtained are discussed.

scholarly journals Exploring Trade-Offs between Specialized Dataflow Kernels and a Reusable Overlay in a Stereo Matching Case Study

2015 ◽  
Vol 2015 ◽  
pp. 1-24 ◽  
Author(s):  
Tobias Kenter ◽  
Henning Schmitz ◽  
Christian Plessl
Keyword(s):  
Stereo Matching ◽  
Design Approach ◽  
Design Concepts ◽  
Trade Offs ◽  
Implementation Approach ◽  
Starting Point ◽  
And Performance ◽  
Hardware Platforms ◽  
Spatial Programming

FPGAs are known to permit huge gains in performance and efficiency for suitable applications but still require reduced design efforts and shorter development cycles for wider adoption. In this work, we compare the resulting performance of two design concepts that in different ways promise such increased productivity. As common starting point, we employ a kernel-centric design approach, where computational hotspots in an application are identified and individually accelerated on FPGA. By means of a complex stereo matching application, we evaluate two fundamentally different design philosophies and approaches for implementing the required kernels on FPGAs. In the first implementation approach, we designed individually specialized data flow kernels in a spatial programming language for a Maxeler FPGA platform; in the alternative design approach, we target a vector coprocessor with large vector lengths, which is implemented as a form of programmable overlay on the application FPGAs of a Convey HC-1. We assess both approaches in terms of overall system performance, raw kernel performance, and performance relative to invested resources. After compensating for the effects of the underlying hardware platforms, the specialized dataflow kernels on the Maxeler platform are around 3x faster than kernels executing on the Convey vector coprocessor. In our concrete scenario, due to trade-offs between reconfiguration overheads and exposed parallelism, the advantage of specialized dataflow kernels is reduced to around 2.5x.

Theoretizing A New Sustainable Business Event: Extension of Mair and Jago Model

2015 ◽  
Vol 3 (2) ◽  
pp. 55
Author(s):  
Norol Hamiza Zamzuri ◽  
Khairil Wahidin Awang ◽  
Yuhanis Abdul Aziz ◽  
Zaiton Samdin
Keyword(s):  
Social Impact ◽  
Geographical Area ◽  
Infrastructure Development ◽  
Structured Interviews ◽  
Sustainable Business ◽  
Knowledge Resources ◽  
Business Events ◽  
And Performance ◽  
Event Based

The growth of the event sector is underpinned by the demand of organizing a business event.  Thus, it leads to an increase in economic and social impact. However, the problems from the growth of this sector potentially results from the use of several event materials, transportation and infrastructure development.  Organizing a green event is seen as one of the strategies to reduce the environmental impact.  Therefore, the aim of this paper is to explore the issues involved throughout the process of greening an event by applying Mair and Jago Model.  Semi-structured interviews were conducted with event managers from six Malaysia business event companies that encourage green practices during their event.  Findings suggest that impact, initiative, support and performance motivates event organizers in organizing a green event.  It has also been found that knowledge, resources and behaviour are the barriers faced by event organizers throughout the process of organizing a green event.  Based on the findings it appears that two important factors have emerged from the data collection and analysis that showed a deviation from the Mair and Jago Model, namely “impact” for the motivation element and “support” for the barrier element.  The main limitation of this study was the scope of the study; as it only focuses on business events.  However, as the main purpose of this study is to explore the issues of organizing a green event, it has been found that there are other issues need to be explored in other contexts and geographical area.  Apart from this, as this is a case study, it can only replicate according to the circumstances of this case study. However, this study can be generalized in terms of the theory that has emerged from it.  It is suggested that further research should explore more issues in other contexts and geographical areas. 

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