Alex Shum
University of Hong Kong
Self-efficacySquare rootHysteresisMathematical optimizationEngineeringPsychologyNonlinear systemActuatorHamilton–Jacobi–Bellman equationPolygon meshEdge (geometry)MathematicsComputer scienceExact solutions in general relativityRate of convergenceControl theoryConvergence (routing)MagnetostrictionMotion planningSmart materialViscosity solutionOptimal control
12Publications
3H-index
55Citations
Publications 11
Newest
#1Luke K. Fryer (HKU: University of Hong Kong)H-Index: 14
#2Alex Shum (HKU: University of Hong Kong)H-Index: 3
Last. Peter W. K. Lau (HKU: University of Hong Kong)H-Index: 8
view all 4 authors...
Abstract How students experience educational environments and the interconnections between their readiness, task experiences and their long-term desire to reengage with course content are critical questions for educators. Research postgraduate students (n = 310) at a research-intensive university in Hong Kong, engaging in a 24-h introductory teaching course, participated in this study. Learner readiness for the course was assessed as prior Domain interest, self-efficacy, and knowledge. Subsequen...
1 CitationsSource
#1Alex Shum (HKU: University of Hong Kong)H-Index: 3
#2Peter W. K. Lau (HKU: University of Hong Kong)H-Index: 8
Last. Luke K. Fryer (HKU: University of Hong Kong)H-Index: 14
view all 3 authors...
Graduate students often teach in higher education but lack necessary experience, while enrolment for teacher-training courses is often voluntary with varying standards. The development and malleabi...
2 CitationsSource
#1Luke K. FryerH-Index: 14
#2Alex ShumH-Index: 3
1 CitationsSource
#1Alex Shum (UW: University of Waterloo)H-Index: 3
#2Kirsten Morris (UW: University of Waterloo)H-Index: 22
Last. Amir Khajepour (UW: University of Waterloo)H-Index: 52
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The ordered upwind method (OUM) is used to approximate the viscosity solution of the static Hamilton---Jacobi---Bellman with direction-dependent weights on unstructured meshes. The method has been previously shown to provide a solution that converges to the exact solution, but no convergence rate has been theoretically proven. In this paper, it is shown that the solutions produced by the OUM in the boundary value formulation converge at a rate of at least the square root of the largest edge leng...
3 CitationsSource
#1Alex Shum (UW: University of Waterloo)H-Index: 3
#2Kirsten Morris (UW: University of Waterloo)H-Index: 22
Last. Amir Khajepour (UW: University of Waterloo)H-Index: 52
view all 3 authors...
The optimal path planning problem is considered for rovers. Tip-over risk is accurately modelled using direction dependence. In the previous direction-independent model, the value function was approximated using the Fast Marching Method (FMM). The risk was not accurately modelled. Solar energy is considered here for the first time. Minimizing path length, obstacle avoidance and soil risk are also considered. For a direction-dependent model, the value function in the optimal path planning problem...
24 CitationsSource
#1Alex ShumH-Index: 3
1 Citations
May 20, 2012 in ISCAS (International Symposium on Circuits and Systems)
#1Baha Alzalg (WSU: Washington State University)H-Index: 6
#2Catalina V Anghel (U of T: University of Toronto)H-Index: 5
Last. Chai Wah Wu (IBM)H-Index: 35
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The optimal power flow problem is concerned with finding a proper operating point for a power network while attempting to minimize a cost function and satisfy network constraints. We analyze the optimal power flow problem subject to contingency constraints and investigate the relationship between the cost of the optimal power flow problem and network topology. We find that when the network topology is that of a small world graph or a scale-free graph, the optimal power flow problem is robust in ...
1 CitationsSource
#1Baha AlzalgH-Index: 6
#2Catalina V AnghelH-Index: 5
Last. Alex ShumH-Index: 3
view all 6 authors...
#1Sina ValadkhanH-Index: 5
#2Kirsten Morris (UW: University of Waterloo)H-Index: 22
Last. Alex Shum (UW: University of Waterloo)H-Index: 3
view all 3 authors...
Magnetostrictive materials can be used to construct high bandwidth actuators with a higher force and a larger stroke than are provided by other materials. However, their use is hindered by their complex nonlinear and hysteretic response. This response displays a significant dependence on mechanical loading. In this paper, a modeling technique is introduced for reproducing hysteresis curves at different loads. The classic Preisach model is used, although the approach can be used to include load d...
19 CitationsSource
#1Alex ShumH-Index: 3
Hysteresis is exhibited by many physical systems. Smart materials such as piezoelectrics, magnetostrictives and shape memory alloys possess useful properties, especially in the field of micropositioning, but the control of these systems is difficult due to the presence of hysteresis. An accurate model is required to predict the behaviour of these systems so that they can be controlled. Several hysteresis models including the backlash, elastic-plastic and Preisach operators are discussed in detai...
1 Citations