Engineering Commons^™

Process Modelling Support For The Conceptual Modelling Phase Of A Simulation Project, Cathal Heavey, John Ryan

Conference papers

While many developments have taken place around supporting the model coding task of simulation, there are few tools available to assist in the conceptual modelling phase. Several authors have reported the advantages of using process modelling tools in the early phases of a simulation project.

This paper provides an overview of process modelling tools in relation to their support for simulation, categorizing the tools into formal method and descriptive methods. A conclusion from this review is that none of the tools available adequately support the requirements gathering phase of simulation. This is not surprising as none of the process modelling …

Experimental Investigation On Voip Performance And The Resource Utilization In 802.11b Wlans, Miroslaw Narbutt, Mark Davis

Conference papers

In a shared medium network like the 802.11b WLAN, predicting the quality of VoIP calls from the resource usage of the wireless medium is highly desirable. Analyzing the bandwidth usage at the L2/MAC layer may be especially useful for potential QoS provisioning and call admission schemes. This paper experimentally investigates the relationship between resource utilization in WLANS and the quality of VoIP calls transmitted over wireless medium. Specifically we evaluate how the amount of free bandwidth influences transmission impairments (i.e. delay, loss and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a …

Experimental Investigation Of The Effects Of Background Traffic Loads On Streamed Video Over 802.11b Wlans, Tanmoy Debnath, Nicola Cranley, Mark Davis

Conference papers

Video is a frame based media and video streaming is often described as “bursty” which has a large impact on the Quality of Service of the video streaming application over WLAN networks. In this paper the impact of background load on the performance of streaming MPEG-4 video with a video server located on the wired network streaming to wireless client is analysed. We experimentally investigate the performance for both uplink and downlink loads. The performance is measured in terms of the key parameters of bit rate, loss rate and mean delay since these are the primary factors that affect the …

Experimental Analysis Of An 802.11b Wireless Mesh Network, Brian Keegan, Karol Kowalik, Mark Davis

Conference papers

Wireless Mesh Networks (WMNs) are a type of radio-based network which require minimal configuration and infrastructure. They can be built using relatively low cost radio and computing platforms. In this paper we attempt to analyze the performance of a simple WNM using various packet sizes as well as a multi-hop WMN.

Performance Of A Variable Speed Double-Fed Induction Generator Wind Turbine During Network Voltage Unbalance Conditions, Joseph Kearney, Michael Conlon

Conference papers

The issues of the negative performance of DFIG’s due to supply network voltage unbalance are outlined in this paper. The paper shows the effects that voltage unbalance can have on a DFIG, using the power simulation program DigSilent. The results from simulations show that voltage unbalance affects the both the induction generator and the rotor converter, due to the high unbalanced currents generated. The ability to modify the control strategy of a DFIG to compensate for voltage unbalance is outlined and a proposal to build a test-rig suitable to implement such a system is suggested.

The Effects Of Background Traffic On The End-To-End Delay For Video Streaming Applications Over Ieee 802.11b Wlan Networks, Nicola Cranley, Mark Davis

Conference papers

The bursty nature of video streaming applications is due to the frame-based structure of video and this has an important impact on the resource requirements of the WLAN, affecting its ability to provide Quality of Service (QoS) particularly under heavily loaded conditions. In this paper we analyse this bursty behaviour in depth. We show how each video frame is queued at the AP causing the packet delay to vary in a sawtooth manner that is related to the frame rate, the number of packets per video frame, and the packet size. We infer the maximum background traffic load that can …

Technology Influences On Small Logistics Providers: A Case Study Analysis, Pietro Evangelista, Alan Mckinnon, Edward Sweeney

Conference papers

ICT has triggered many changes in the logistics service industry. New technology is reshaping the organisation and structure of this industry as ICT impacts significantly on the operations of 3PLs. Within this process, while large 3PLs are gaining substantial benefits from technology usage, the nature of changes resulting from ICT usage in small 3PLs remains unclear. This is critical particularly for those markets populated by a high number of small 3PLs such as the Italian logistics industry. From the research point of view, there is still a gap in the literature where the role of technological capability in small 3PLs …

Outsourcing In Ireland: A Literature Review And Survey Perspective To Construct An Outsourcing Roadmap, Aoife O'Riordan, Edward Sweeney

Conference papers

This paper investigates what is happening in Ireland at the moment regards outsourcing. It looks into the literature review and the survey conducted. The research took place over a period of two years, initially as a literature review, and then the survey was conducted through the mediums of e-mail and the postal service. The survey analysis found that Ireland was the most likely place for Irish companies to outsource to, and that nearly 40 percent of the companies that have been surveyed have started on their latest outsourcing initiative since 2004. This indicates that outsourcing is still important on the …

The Application Of Learning Skills In An Engineering Programme, Leslie Shoemaker

Conference papers

At the Dublin Institute of Technology, an engineering programme in the School of Control Systems and Electrical Engineering has successfully incorporated a study skills module into the core curriculum. The module, titled Academic Development and Key Skills, is part of the first year of the programme and has a two-fold purpose. Primarily the goal is to assist the students with the transition from second level education to third level by teaching them a more competent learning style. This, in turn, helps to create a positive impact with respect to the retention of this student group within the programme. The second …

Moving A Part-Time Engineering Course To A Student-Centred Paradigm, Kevin Kelly

Conference papers

This paper is a further reflection on two conference papers presented at the World Conference for Continuing Engineering Education (WCCEE) in Vienna in April 2006 and National University of Ireland (NUI) Galway Conference: The Challenge of Diversity: Teaching, Support and Student Learning , June 2006. Both conference papers dealt with different aspects of my experiences of the theoretical and pedagogical changes required in re-design and delivery of a part-time engineering programme for the continuing education development of electrical engineers in the workforce.

Study Of Same-Lane And Inter-Lane Gvw Correlation, Colin C. Caprani, Bernard Enright, E. J. O'Brien

Conference papers

Extensive work has been done over the last two decades on the simulation of traffic loading on bridges. The methodology used is to generate a number of years of simulated traffic and to use extreme value statistics to predict more accurately the characteristic loading for a given bridge. The parameters and probability distributions used in the Monte Carlo simulation must be based on observed sample traffic data. Some previous studies have made unsubstantiated assumptions regarding correlation between the Gross Vehicle Weights (GVW) of trucks in the same lane, or between trucks in adjacent, same direction lanes. For this paper, an …

Finding The Distribution Of Bridge Lifetime Load Effect By Predictive Likelihood, Colin C. Caprani, E. J. O'Brien

Conference papers

To assess the safety of an existing bridge, the loads to which it may be subject in its lifetime are required. Statistical analysis is used to extrapolate a sample of load effect values from the simulation period to the required design period. Complex statistical methods are often used and the end result is usually a single value of characteristic load effect. Such a deterministic result is at odds with the underlying stochastic nature of the problem. In this paper, predictive likelihood is shown to be a method by which the distribution of the lifetime extreme load effect may be determined. …

An Experimental Analysis Of The Call Capacity Of Ieee 802.11b Wireless Local Area Networks For Voip Telephony, Brian Keegan, Mark Davis

Conference papers

In this paper we present the results from an experimental study of the call capacity of an IEEE 802.11b network when using VoIP telephony. Experiments include increasing the number of VoIP users in a wireless test-bed and increasing the level of background traffic until network saturation occurs. The experiments allow us to perform an analysis of the access point (AP) buffer dynamics. Results show that the network is capable of supporting up to 16 VoIP stations (STAs). Due to the operation of the IEEE 802.11 medium access control (MAC) mechanism, the AP acts as a bottleneck for all traffic destined …

Gauging Voip Call Quality From 802.11 Wlan Resource Usage, Miroslaw Narbutt, Mark Davis

Conference papers

In this paper we experimentally study the relationship between resource utilization in the wireless LAN and the quality of VoIP calls transmitted over the wireless medium. Specifically we evaluate how its overall capacity is shared between three basic MAC bandwidth components (load, access and free) as the number of VoIP calls increases and how it influences transmission impairments (delay, loss and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a WLAN probe application that passively “sniffs” packets at the L2/MAC layer of the wireless medium and analyses their headers and temporal characteristics. …

The Impact Of Tcp Sliding Window On The Performance Of Ieee 802.11 Wlans, Enrique Roques Gomez, Mark Davis

Conference papers

In this paper the TCP sliding window mechanism is experimentally investigated as one of the possible causes of the unfairness often observed as IEEE802.11 wireless LANs. We show how by appropriately sizing the sliding window it is possible to re-introduce fairness into the operation of the WLAN.

Effect Of Free Bandwidth On Voip Performance In 802.11b Wlan Networks, Miroslaw Narbutt, Mark Davis

Conference papers

In this paper we experimentally study the relationship between bandwidth utilization in the wireless LAN and the quality of VoIP calls transmitted over the wireless medium. Specifically we evaluate how the amount of free bandwidth decreases as the number of calls increases and how this influences transmission impairments (i.e. delay, loss and jitter) and thus degrades call quality. We show that the amount of free bandwidth is a good indicator for predicting VoIP call quality.

A Comparison Of Time-Domain Time-Scale Modification Algorithms, David Dorran, Robert Lawlor, Eugene Coyle

Conference papers

Time-domain appraoches to time-scale modification are popular due to their ability to produce high quality results at a relatively low computational cost. Within the category of time-domain implementations quite a number of alternatives exist, each with their own computational requirements and associated output quality. This paper provides a computational and objective output quality assessment of a number of popular time-domain time-scaling implmentations; thus providing a means for developers to identify a suitable algorithm for their application of interest. In addition, the issues that should be considered in developing time-domain algorithms are outlines, purely in the context of a waveform editing …

Women, Engineering And Research: Providing Choice And Balance, Cecilia Chan, Mike Murphy

Conference papers

“Research cannot reach its full potential when half the population is excluded from its activities”1. Women researchers in engineering remain a minority in both Higher Education and industry in Ireland. Recent statistics of women graduating in science and engineering indicated an increase (a slow increase) but the numbers moving through to completion of PhD and careers in academia or industry remain quite low. Statistics on women in professorial and senior positions within the engineering sector also remains low. The educated workforce produced in Ireland by its education system is acknowledged as a key factor in attracting international investment to the …

Addressing The Challenges That Are Emerging In The Continued Increase In Ppp Use In The Republic Of Ireland, Louis Gunnigan, David Eaton

Conference papers

The Irish Government’s Public-Private Partnership (PPP) programme of pilot projects is now reaching its conclusion and PPP has become established as a key element in the strategy for provision of public sector facilities. Compiled through a literature review as part of a PhD level research project, this paper examines organisational culture differences between the public and private sectors and assesses the potential affect of these differences on the future development of the Irish PPP programme. By relating organisational culture differences to the emerging challenges relating to risk, value and innovation, it is evident that the lack of a partnering environment …

Recruiting First Year Engineering Undergraduates, Eddie Conlon

Conference papers

This paper presents findings of three surveys conducted with first year students in the Faculty of Engineering in the Dublin Institute of Technology. It presents evidence on the reasons students study engineering, their sources of information on higher education programmes and the people who influence their decision to do engineering. It shows there are gaps in the students’ knowledge of their programmes and also between their expectations and their experience of their course. Some proposed areas of action are identified to increase both recruitment and retention. It is argued that projecting an image of engineering as a creative activity would …

Determination Of Characteristic Bridge Daf Using Dynamic Finite Element Analysis Of Critical Static Loading Scenarios, Colin C. Caprani, Paraic Rattigan, Arturo Gonzalez, E. J. O'Brien

Conference papers

The development of accurate codes for the design of bridges and the evaluation of existing structures requires adequate assessment of site-specific heavy traffic loading and also the dynamic interaction that may occur as this traffic traverses the structure. Shortcomings in current design codes occur due to the relatively independent manner in which critical static loading values and the corresponding allowance for dynamic amplification factor (DAF) are obtained. It is important that an approach is adopted that allows for the reduced probability of both high static loading and high dynamic amplification occurring simultaneously. Consideration of only relevant critical loading events will …

Statistical Computation For Extreme Bridge Traffic Load Effects, Colin C. Caprani, E. J. O'Brien

Conference papers

The maintenance of highway infrastructure constitutes a major expenditure in many countries. This cost can be reduced significantly by minimizing the repair or replacement of highway bridges. In the assessment of existing bridges, the strength estimate tends to be more accurate than that of traffic loading, due to the more variable nature of loading. Recent advances in the statistical analysis of highway bridge traffic loading have resulted in more accurate forecasts of the actual loading to which a bridge is subject. While these advances require extensive numerical computation, they can significantly improve the accuracy of the calculation. This paper outlines …

Bridge Dynamics And Loading, Colin C. Caprani, Eugene O'Brien, Arturo Gonzalez, Yingyan Li, Paraic Rattigan, Niall Harris

Conference papers

Recent UCD research on dynamic bridge-truck interaction and bridge traffic loading in general is reported. The accuracy of bridge traffic load assessment has been significantly improved by identifying the differences in the sources of traffic loading on short- to medium-span bridges and treating them separately. It is shown that results can be significantly improved by treating 1-,2-,3- and 4-truck loading events separately. Gaps between trucks are also identified as a critical issue that strongly influences the frequency of key3-and 4-truck events. Trends in the dynamics of traffic loading are identified using simple force models on simply supported beams. It is …

Estimating Risk Of Failure Of Engineering Structures Using Predictive Likelihood, Colin C. Caprani, A. Bordallo-Ruiz, E. J. O'Brien

Conference papers

It has been common engineering practice to define characteristic values for loading and capacity of structures in order to assess the structural capacity of existing structures. This approach, yet practical and intuitive, lead to the comparison of deterministic values (characteristic values) that had to represent all the variability of the problem and is considered to be conservative, as usually loading is overestimated and capacity underestimated, yielding to calculations with high safety margins for the extreme events. Probabilistics methods have tried to overcom e this limitation by computing the overall probability of failure (Pf) for the lifetime of the structure, taking …

Study Of Same-Lane And Inter-Lane Gvw Correlation, Bernard Enright, Eugene J. O'Brien, Colin C. Caprani

Conference papers

The methodology used is to generate a number of years of simulated traffic and to use extreme value statistics to predict more accurately the characteristic loading for a given bridge. The parameters and probability distributions used in the Monte Carlo simulation must be based on observed sample traffic data. Some previous studies have made unsubstantiated assumptions regarding correlation between the Gross Vehicle Weights (GVW) of trucks in the same lane, or between trucks in adjacent, same-direction lanes. For this paper, an extensive database of Dutch Weigh-in-Motion data is analysed. Data are collected from two same-direction lanes and are time-stamped to …

A Critical Appraisal Of The Roles Of Public Sector Employees In The Provision Of Educational Buildings Under A Public Private Partnership (Ppp) In The Republic Of Ireland, Louis Gunnigan, David Eaton

Conference papers

Public-Private Partnership (PPP) has now become established as a key element in the Irish Government’s strategy in the provision of school buildings. Specific guidelines have been implemented to define the public sector role in a PPP in Ireland and these guidelines represent a significant change in role from those in the traditional schools procurement process. Through a literature review, this paper maps the PPP process and establishes the new tasks that public sector employees must carry out in the adoption of PPP. The new knowledge, skills and competence (KSC) required to carry out these tasks are noted. Whilst existing literature …

Harmonically Combined Contour Icons For Concurrent Auditory Display, Charlie Cullen, Eugene Coyle

Conference papers

This paper considers the harmonic combination of basic melodic shapes known as contour icons in concurrent auditory displays. Existing work in the field (such as that concerning earcons) has considered the combination of patterns designed using low level cognitive features, and so effective streaming is difficult. This work investigates means by which musical patterns with high level cognitive features (such as contour) representing data values can be rendered concurrently, so that multiple data sets can be effectively conveyed using an auditory display. The detection and comprehension of harmonically combined contour icons was tested in comparison to those combined uniquely (non …

Musical Pattern Design Using Contour Icons, Charlie Cullen, Eugene Coyle

Conference papers

This paper considers the use of Contour Icons in the design and implementation of musical patterns, for the purposes of detection and recognition. Research work had endeavoured to deliver musical patterns that were both distinct and memorable, and to this end a set of basic melodic shapes were introduced using a Sonification application called TrioSon that had been designed for the purpose. Existing work in the field (such as that concerning Earcon design) has considered the mechanisms by which patterns may be made distinctive, but it is argued that separate consideration must be given to the method of making such …

Study Of The Behaviour Of Video Streaming Over Ieee 802.11b Wlan Networks, Nicola Cranley, Mark Davis

Conference papers

The performance of video streaming over WLAN networks is not only influenced by the state of the network but also by the encoding configuration parameters of the video stream, such as the video content being streamed, how the vide is encoded and how it is transmitted. In this paper, we analyse the unique delay characteristic of video streaming applications in a WLAN environment. We show that the “burstiness” of video is due to the frame-based nature of encoded video. We show how each video frame is transmitted as a burst of packets that is queued at the Access Point causing …

Experimental Comparison Of Wired Versus Wireless Video Streaming Over Ieee 802.11b Wlans, Tanmoy Debnath, Nicola Cranley, Mark Davis

Conference papers

In this paper the performance of streaming MPEG-4 video with a video server located on the wired network streaming to wireless clients is compared with the performance of a video server located in the wireless network streaming to wireless video clients. We experimentally investigate the performance for a number of concurrent video streams with varying video frame sizes, frame rates and packetisation schemes. The performance is measured in terms of the key parameters of bit rate, loss rate and mean delay. We show how that there is a trade-off for these parameters for a wired and wireless located server. We …