Nick Sirmas presented his PhD thesis seminar

Yesterday, one of our longest serving graduate students presented his PhD thesis seminar.  The title of the talk was “modelling of shock waves in granular media at the micro and macroscopic levels.”  Unfortunately, supervisor Dr. Matei Radulescu could not be present but our classroom was standing room only – we had a great turnout.  Congrats, Nick! Nice work. Thanks to the MCG grad student association that provided us with timbits and coffee (made all the more special because my roll-up-the-rim netted me a free coffee). 🙂 

Advertisements

Dominic Robillard to present next Wednesday

The next speaker in our student seminar series will be Dominic Robillard. Dominic will be giving a talk titled “Development of a stair-climbing robot and a hybrid stabilization system for self-balancing robots”.

 

Where: CBY D207

Date: Wednesday June 25th, 2014

Time: 14:30

The abstract of the talk is given below. Hope to see you all there!

 

Development of a stair-climbing robot and a hybrid stabilization system for self-balancing robots

Candidate: Dominic Robillard
Supervisor: Dr. Eric Lantaigne

 

Abstract:

Self-balancing robots are unique mobile platforms that stay upright on two wheels using a dynamic control system. They can turn on the spot using differential steering and have compact form factors that limit their required floor space. However they have major limitations: they cannot stand-up on their own, climb stairs, or overcome large obstacles. The first part of this research proposes a novel design to address the aforementioned issues related to stair-climbing, standing-up, and obstacles. A single revolute joint is added to the centre of a four-wheel drive robot onto which an arm is attached, allowing the robot to successfully climb stairs and stand-up on its own from a single motion. A model and simulation of the balancing and stair-climbing process are derived, and compared against experimental results with a custom robot prototype. The second part of this research examines a control system for an inverted pendulum equipped with a gyroscopic mechanism for integration into self-balancing robots. It improves disturbance rejection during balance, and keeps equilibrium on slippery surfaces. The model of a gyroscope mounted onto an actuated gimbal was derived and simulated. To prove the concept worked, a custom-built platform showed it is possible for a balancing robot to stay upright with zero traction under the wheels.

Aslan Farjam and Guillaume Archambault to present on Wednesday

The next speakers in our student seminar series will be Aslan Farjam and Guillaume Archambault . Aslan and Guillaume will be giving a talk entitled “Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing” and “Lay-up Moulding of a Carbon Fiber Reinforced Polymer Composite on a Cold Sprayed Metallic Layer”, respectively.

Where: CBY D207

Date: Wednesday June 11th, 2014

Time: 14:30

The abstracts of the talks are given below. Hope to see you all there!

 

****After the seminars, coffee and doughnuts will be served in CBY-A218 (courtesy of uOMEGA)****

 

Candidates: Aslan Farjam and Guillaume Archambault

Supervisor: Dr. Bertrand Jodoin

 

Abstract (AF):

In this work, different percentages of pure aluminum and alumina (ceramic) powder mixtures were deposited through wire mesh masks on an aluminum substrate to produce pyramidal array of fins using cold spray technology. Using aluminum-alumina powder mixtures instead of pure aluminum powder to produce net-fin shapes could have many valuable properties, such as being cost-effective, and having useful nozzle clogging prevention properties during cold spray. Heat transfer and pressure drop tests were carried out using different ranges of applicable Reynolds numbers to compare each coating mixture and heat transfer capability. Numerical simulations were performed to model the fluid dynamics of the flow interaction, heat transfer, and pressure drop in each sample. Experimental measurements matched with the numerical calculations. The results indicate that by increasing the percentage of alumina in the aluminum-alumina powder mixture resulted in only a small variation in heat transfer of pyramidal fins. Furthermore, the numerical results open up new avenues in predicting other possible powder mixtures and fin shapes using numerical models.

Abstract (GA):

The aerospace industry is continually investigating innovative techniques to increase flying efficiency. As a consequence of innovation, the cost of flying will be reduced; as the aircraft’s mechanical performance improves. To achieve an important weight reduction, the fuselage of aircrafts like The Boeing Company’s 787 ‘‘Dreamliner’’ is mainly made of carbon fiber based composites. By offering a low material specific strength-to-weight ratio, carbon fiber reinforced composites are state of the art materials for the aerospace industry.

The in-flight concern of having the aircraft subjected to lightning is an ongoing problem for the safety of the crew and passengers. In the event of lightning striking the fuselage, localized melting of the composite will commonly occur, as the medium is highly resistive. While melting the composite, the electrical current will dissipate through a specially designed embedded metallic mesh located below the carbon fiber composite. Consequently, after landing, the airplane will be out of service until the molten area is repaired. As of today, a solution to prevent localized melting of the composite is to rivet heavy metallic plates on the components prone to lightning.

To resolve weight issues arising from heavy riveted plates, it would be practical to deposit thin layers of conductive material on the surface of the carbon fiber based composite. Unfortunately, operating temperatures in conventional thermal spray processes would degrade the carbon fiber based composites. For instance, a new innovative technique, combining Cold Gas Dynamic Spray and lay-up moulding of composites, would enable production of metallic coated carbon fiber based composites.The present study presents a description of the experimental approach used to develop metallic coated composites while showing the manufacturability of such components. Technical barriers, such as obtaining a low resistivity metallized composite and producing an easily removable metallic layer from the mould during lay-up moulding, are essential for the production of such aerospace materials. The results produced in the University of Ottawa Cold Spray Laboratory showed that composites of various shapes, low porosity, high conductivity and easily removable from the metallic mould were possible to produce.

Philippe Dupuis and Yannick Cormier to present next Wednesday

The next speakers in our student seminar series will be Philippe Dupuis and Yannick Cormier . Philippe and Yannick will be giving a talk entitled “Production and Flow Characterization of Pyramidal Fin Arrays using Cold Gas Dynamic Spraying” and “Performance of Pyramidal Fin Arrays”, respectively.

Where: STE H0104

Date: Wednesday May 14th, 2014

Time: 14:30

The abstracts of the talks are given below. Hope to see you all there!

 

Candidates: Philippe Dupuis and Yannick Cormier

Supervisor: Dr. Bertrand Jodoin

 

Background:

Energy efficiency has become a growing concern in a world driven by a fossil fuel economy. To this end, increasing the performance and decreasing cost, weight and volume of gas turbines has become a critical research focus. Heat exchangers such as recuperators and intercoolers help improve the efficiency of gas turbines by recovering the waste heat generated by this process. Compact heat exchangers with unit cells using wire mesh as the internal heat transfer surface have been developed at Brayton Energy Canada, but several difficulties are encountered with conventional joining techniques. Cold Spray was successfully used to deposit an outer layer and the current study focuses on the viability of depositing fins on this outer layer. Due to process restrictions, the pressure drop across the fin array needs to be minimal, while maintaining a very high heat transfer rate per unit area.

Presentation 1: Philippe Dupuis

Title: Production and Flow Characterization of Pyramidal Fin Arrays using Cold Gas Dynamic Spraying

The focus of this study is the manufacturability of pyramidal fin arrays produced using the cold spray process. This work also includes a section regarding the relevant background information on gas turbine generators and heat exchangers. The cold spray process is also detailed, and the technique used to obtain near-net shaped pyramidal pin fin arrays of various sizes and fin densities is discussed. The Particle Image Velocimetry flow characterization method has been used to determine the flow structures around the pin fin arrays and is discussed.

 

 

Presentation 2: Yannick Cormier

Title: Performance of Pyramidal Fin Arrays

This work studies the heat transfer and fluid mechanics performance of pyramidal fin arrays produced using the cold spray process. Empirical correlations were determined between the Reynolds number and the Nusselt number for these shapes of fins. These relations were used in a numerical model in order to determine the most appropriate fin array geometry, depending on target specifications, fluid input conditions and spatial constraints. The fins produced using the cold spray process outperform traditional straight-cut fins at the same fin density due to increased fluid mixing and turbulence caused by the discontinuity of these features. The adhesion strength of the fins has also been quantified. The effects of varying fin height, base dimensions, spacing and densities of these pin fins have been characterized for both the thermal performance and for adhesion strength.

 

Amir Behnamian to present next Wednesday

The next speaker in our student seminar series will be Amir Behnamian. Amir will be giving a talk titled “Measurements of scalar probability density functions and conditional expectations in uniformly sheared turbulence”.

 

Where: STE H0104

Date: Wednesday May 7th, 2014

Time: 14:30

The abstract of the talk is given below. Hope to see you all there!

 

Measurements of scalar probability density functions and conditional expectations in uniformly sheared turbulence

Candidate: Amir Behnamian
Supervisor: Dr. Stavros Tavoularis

 

Abstract:

High resolution, multi-sensor, hot/cold-wire measurements were made in passively heated, uniformly sheared turbulence in a wind-tunnel. Measurements were focused on terms in the scalar PDF equation that require closure models. Unlike previous studies, which considered a single combination of velocity and scalar fields at a time, we investigated three different scalar fields embedded in the same nearly homogeneous turbulence with three passively superimposed temperature fields, namely a transversely homogeneous temperature field with a uniform mean gradient, and two inhomogeneous temperature fields, the plume of a heated line source and a thermal mixing layer. The use of uniformly sheared flow allowed us to isolate the effects of scalar inhomogeneity and initial conditions by evaluating the results in the three scalar fields. Thus, the measurements covered a wide range of scalar field conditions and set the ground for a conclusive comparison.

Scott Audette to present next Wednesday

The next speaker in our student seminar series will be Scott Audette. Scott will be giving a talk titled “Mechanical properties of aerospace composite parts made from stitched multilayer 3D carbon fibre preforms”.

 

Where: CBY B205

Date: Wednesday April 30th, 2014

Time: 14:30

The abstract of the talk is given below. Hope to see you all there!

 

Mechanical properties of aerospace composite parts made from stitched multilayer 3D carbon fibre preforms

Candidate: Scott Audette
Supervisor: Dr. Francois Robitaille

 

Abstract:

Producing composite parts using low-cost processes such as resin transfer moulding (RTM) has received much interest in the aerospace industry. RTM manufactured components require near net shape preforms which closely fit mould cavities. To reduce labour costs associated with composite production, automated preforming processes must be utilized. However, obtaining reproducible high quality preforms is required for manufacturing consistent high quality parts. Stitched multilayer 3D non crimp fabric preforms are well suited for automation and an investigation into quality and performance of components manufactured from these preforms is required. This work provides an initial evaluation of quality and mechanical properties of components made from stitched multilayer 3D non crimp fabric preforms using RTM. Similar sized flat plates of varying fibre volume fractions were manufactured to evaluate flexural modulus and strength, short beam strength and drop weight impact resistance of the material. Also, integral reinforced panels (IRPs) featuring a reinforcing section joined to a flat plate of varying laminating sequences were manufactured to evaluate debonding strength between sections. Optical microscopy was performed on component samples to determine quality based on void content and was found to be within acceptable limits for production composites. Flexural modulus was comparable to theoretical expected values, however flexural strength was limited by the presence of transverse stitches. Short beam strength results showed high consistency between specimens and performed well against comparable data. Impact specimens showed consistency among specimens, with reasonable damage resistance. Determining debonding strength proved difficult as different failure modes were observed between IRPs, however, initial baseline values were acquired.

Yu Hu to present next Wednesday

The next speaker in our student seminar series will be Yu Hu. Yu will be giving a talk titled “Human friendly robots”.

 

Where: CBY B205

Date: Wednesday April 23rd, 2014

Time: 14:30

The abstract of the talk is given below. Hope to see you all there!

 

Human Friendly Robots

Candidate: Yu Hu
Supervisor: Dr. Dan-Sorin Necsulescu

 

Abstract:

In this project, a novel human friendly mobile robot navigation controller is investigated. By applying this controller, the mobile robot is able to work in a complicated environment with several humans and other obstacles avoiding them before a collision happens. This robot will have a preference in avoiding humans over other obstacles keeping human safety as its first consideration. To achieve this goal, three problems have to be solved. The first one is the robot should be able to “see” the environment and distinguish the human and the obstacles. The functions of human sensor and sonar sensor are presented. A new sensor fusion method for combining the information collected by these two kinds of sensors based on Dempster-Shafer evidence theory is also proposed. By using the sensor fusion method, the robot will have a better view of human. The second problem is the robot has to know how to avoid collision. A new navigation algorithm, based on an improved velocity potential field method, is then described. The way of calculating the distances of avoidance based on different kinds of obstacles is presented as well. The last problem is how to make the mobile robot put human as its first priority when avoiding collision. A summary of the methods which are used to protect human is mentioned. According to the simulation and the experimental results, the new mobile robot navigation controller successfully leaded the robot avoid collisions in complicated situations and always put human safety as its first consideration.

 

Steven Recoskie to present on Wednesday

The next speaker in our student seminar series will be Steven Recoskie. Steven will be giving a talk titled “Autonomous, hybrid powered, long ranged airship for surveillance and guidance ”.

 

Where: CBY B205

Date: Wednesday April 16th, 2014

Time: 15:00

The seminar of the talk is given below. Hope to see you all there!

 

Autonomous, hybrid powered, long ranged airship for surveillance and guidance

Candidate: Steven Recoskie
Supervisors: Drs. Eric Lanteigne and Wail Gueaieb

 

Abstract:

With devastating natural disasters on the rise, new technologies are needed to improve search and rescue capabilities. Unmanned aerial vehicles are the ideal candidates for surveying disaster-stricken areas and searching for survivors, however, their range and endurance is limited. The objective of this research was to investigate alternative propulsion methods and flight planning techniques for increasing the flight endurance of unmanned airships. Airship design methodologies were reviewed leading to the development and experimental testing of two hybrid fuel-electric power plants. The mechanical and electrical power was measured and we were able to demonstrate that the proposed system offered a 600% increase in energy density when compared to purely electric systems. Based on this vehicle configuration, a comprehensive multi-objective cost function was developed for flight path optimization using a wavefront expansion path planner. Paths were simulated in large 3D environments incorporating variable wind vector fields generated from computational fluid dynamic analysis on digital elevations maps. Combined with a full dynamic model of the airship and two different control strategies, we have been able to show that the paths generated by the planner lead to significant improvements in path feasibility and energy optimality when compared to using constant wind fields.

 

Evaluation of MCG Graduate Programs

Next week, in lieu of our seminar series, student participation in the evaluation of our MCG graduate programs is being requested.  That means YOU, the students, are being asked for your feedback on our graduate program.  This is part of an evaluation of programs that the University of Ottawa periodically undertakes for quality assurance.  Masters and PhD programs are being evaluated separately.

An important part of this evaluation consists in consulting all students regarding the current situation of the program based on a SWOT analysis (Strengths, Weaknesses, Opportunities and Threats). This meeting will be facilitated by a Specialist from the University of Ottawa’s Centre for University Teaching.

We ask for your participation in a discussion on your program of study.  Participation is voluntary and there will be food provided.

MASTERS STUDENTS:

Date: Friday, March 1st

Time: 2:30 pm to 5:00 pm

Location: Vanier Building Room VNR 1042

Please confirm your attendance:  https://www.surveymonkey.com/s/V5GVVLV

PHD STUDENTS

Date: Thursday, 28th February

Time: From 1:00 pm to 3:30 pm

Location: Vanier Building Room VNR 1042

Please confirm your attendance :  https://www.surveymonkey.com/s/2F8XYDR

Thank you in advance for providing your feedback on the programs.  It will serve to strengthen and improve the program in years to come.