Search results for "ta113"
showing 10 items of 530 documents
Ensemble strategies in Compact Differential Evolution
2011
Differential Evolution is a population based stochastic algorithm with less number of parameters to tune. However, the performance of DE is sensitive to the mutation and crossover strategies and their associated parameters. To obtain optimal performance, DE requires time consuming trial and error parameter tuning. To overcome the computationally expensive parameter tuning different adaptive/self-adaptive techniques have been proposed. Recently the idea of ensemble strategies in DE has been proposed and favorably compared with some of the state-of-the-art self-adaptive techniques. Compact Differential Evolution (cDE) is modified version of DE algorithm which can be effectively used to solve …
Reduced Order Models for Pricing American Options under Stochastic Volatility and Jump-diffusion Models
2016
American options can be priced by solving linear complementary problems (LCPs) with parabolic partial(-integro) differential operators under stochastic volatility and jump-diffusion models like Heston, Merton, and Bates models. These operators are discretized using finite difference methods leading to a so-called full order model (FOM). Here reduced order models (ROMs) are derived employing proper orthogonal decomposition (POD) and non negative matrix factorization (NNMF) in order to make pricing much faster within a given model parameter variation range. The numerical experiments demonstrate orders of magnitude faster pricing with ROMs. peerReviewed
Iterative Methods for Pricing American Options under the Bates Model
2013
We consider the numerical pricing of American options under the Bates model which adds log-normally distributed jumps for the asset value to the Heston stochastic volatility model. A linear complementarity problem (LCP) is formulated where partial derivatives are discretized using finite differences and the integral resulting from the jumps is evaluated using simple quadrature. A rapidly converging fixed point iteration is described for the LCP, where each iterate requires the solution of an LCP. These are easily solved using a projected algebraic multigrid (PAMG) method. The numerical experiments demonstrate the efficiency of the proposed approach. Furthermore, they show that the PAMG meth…
Super-fit and population size reduction in compact Differential Evolution
2011
Although Differential Evolution is an efficient and versatile optimizer, it has a wide margin of improvement. During the latest years much effort of computer scientists studying Differential Evolution has been oriented towards the improvement of the algorithmic paradigm by adding and modifying components. In particular, two modifications lead to important improvements to the original algorithmic performance. The first is the super-fit mechanism, that is the injection at the beginning of the optimization process of a solution previously improved by another algorithm. The second is the progressive reduction of the population size during the evolution of the population. Recently, the algorithm…
Synchronous R-NSGA-II: An Extended Preference-Based Evolutionary Algorithm for Multi-Objective Optimization
2015
Classical evolutionary multi-objective optimization algorithms aim at finding an approx- imation of the entire set of Pareto optimal solutions. By considering the preferences of a decision maker within evolutionary multi-objective optimization algorithms, it is possible to focus the search only on those parts of the Pareto front that satisfy his/her preferences. In this paper, an extended preference-based evolutionary algorithm has been proposed for solving multi-objective optimiza- tion problems. Here, concepts from an interactive synchronous NIMBUS method are borrowed and combined with the R-NSGA-II algorithm. The proposed synchronous R-NSGA-II algorithm uses preference information provid…
A New Augmented Lagrangian Approach for $L^1$-mean Curvature Image Denoising
2015
Variational methods are commonly used to solve noise removal problems. In this paper, we present an augmented Lagrangian-based approach that uses a discrete form of the L1-norm of the mean curvature of the graph of the image as a regularizer, discretization being achieved via a finite element method. When a particular alternating direction method of multipliers is applied to the solution of the resulting saddle-point problem, this solution reduces to an iterative sequential solution of four subproblems. These subproblems are solved using Newton’s method, the conjugate gradient method, and a partial solution variant of the cyclic reduction method. The approach considered here differs from ex…
Quality Management in Service Desk : How Does Service Desk Managers Define and Measure Quality
2018
Many public and private sector organisations are depending on IT services provided by external service providers. The quality of the service affects the customer satisfaction and consequently the customer behaviour. The concept of quality has many meanings in the literature. In this paper, we study how service desk managers perceive the concept of quality and how to manage it in an organisation which has adopted ITIL. Our findings indicate that the quality is seen only in terms of how the agreed service levels are achieved. This view excludes the quality of the processes used to deliver IT services. Quality measurements are reflecting the perception of the concept of quality. peerReviewed
Issues with a course that emphasizes self-direction
2013
In this paper, we examine a master's level course that emphasizes self-direction on the part of students. The course is run by weekly group assignments and requires independent work such that only one mandatory classroom session is arranged each week. Our specific research interests are how students responded to the setting of this kind and whether they demonstrated self-direction during the course. We surveyed the students' view of the course, their group work experience, and their study habits, and analyzed the resultant survey data for themes. The results suggest that while the pass rate was considerably high and the course was regarded as well-organized by the students, there were sever…
High school students' perspective to university CS1
2013
This paper presents a qualitative study of a school-university collaborative project where a game-themed CS1 course was offered as-is to high school students. Our specific interest was to explore the students' experiences with the university level course. Our analyses indicate that immediate and regular support was highly important for student performance, as support of this kind could mitigate issues related to students' orientation towards the high workload of the course. Students who showed academic interest were likely to pass, whereas students lacking self-direction or work efficiency were likely to drop out. Both passed and drop-outs found the course to be a good learning experience. …
Activity Theory as a Lens to Identify Challenges in Surgical Skills Training at Hospital Work Environment
2015
In this paper the concepts from activity theory (AT) are applied for identifying the challenges and contradictions emerging in surgical residentâs curriculum based training at hospital. AT is utilised as a lens to identify contradictions that cause disturbances, problems, ruptures, breakdowns, and clashes which emerge while surgical skills training is implemented in a new way at hospital. We especially aim at finding solutions for contradictions which emerge while the new and old working culture are confronted and the workers are required to balance themselves between the patient care demands and workplace learning requirements. We are using the conceptual theoretical approach to describe…