Search results for "Mod"
showing 10 items of 39605 documents
A new approach for estimating a nonlinear growth component in multilevel modeling
2011
This study presents a new approach to estimation of a nonlinear growth curve component with fixed and random effects in multilevel modeling. This approach can be used to estimate change in longitudinal data, such as day-of-the-week fluctuation. The motivation of the new approach is to avoid spurious estimates in a random coefficient regression model due to the synchronized periodical effect (e.g., day-of-the-week fluctuation) appearing both in independent and dependent variables. First, the new approach is introduced. Second, a Monte Carlo simulation study is carried out to examine the functioning of the proposed new approach in the case of small sample sizes. Third, the use of the approac…
Depressive symptoms during adolescence: Do learning difficulties matter?
2011
To examine whether learning difficulties play a role in depressive symptoms, 658 Finnish adolescents were asked to complete scales for depression three times during the transition to post-comprehensive education. They also reported on their learning difficulties and feelings of inadequacy as a student. The results showed that learning difficulties prospectively predicted depressive symptoms. Moreover, the impact of learning difficulties was mediated via inadequacy as a student: learning difficulties predicted feelings of inadequacy as a student which, in turn, contributed to greater increases in depressive symptoms. Finally, gender moderated the association between learning difficulties an…
Surrogate-assisted evolutionary multiobjective shape optimization of an air intake ventilation system
2017
We tackle three different challenges in solving a real-world industrial problem: formulating the optimization problem, connecting different simulation tools and dealing with computationally expensive objective functions. The problem to be optimized is an air intake ventilation system of a tractor and consists of three computationally expensive objective functions. We describe the modeling of the system and its numerical evaluation with a commercial software. To obtain solutions in few function evaluations, a recently proposed surrogate-assisted evolutionary algorithm K-RVEA is applied. The diameters of four different outlets of the ventilation system are considered as decision variables. Fr…
Seeking Technical Debt in Critical Software Development Projects : An Exploratory Field Study
2016
In recent years, the metaphor of technical debt has received considerable attention, especially from the agile community. Still, despite the fact that agile practices are increasingly used in critical domains, to the best of our knowledge, there are no studies investigating the occurrence of technical debt in critical software development projects. The results of an exploratory field study conducted across several projects reveal that a variety of business and environmental factors cause the occurrence of technical debt in critical domains. Using Grounded Theory method, these factors are categorized as ambiguity of requirement, diversity of projects, inadequate knowledge management, and res…
Supporting Agile Development by Facilitating Natural User Interaction with Executable Formal Specifications
2011
Agile development benefits from fast feedback from various stakeholders. If implemented in a suitable way, formal methods can enhance the agile development process. With an executable formal specification, it is possible to analyse and simulate the behaviour of the target system before it is being built. However, for the users' and developers' natural participation in the development process, it is necessary to use a real end-user interface and bind it to the execution environment being used in the simulations and animations. This requires, though, that the execution model used to simulate the specification is appropriately changed to facilitate the use of these user interfaces. The authors…
Developing cloud business models: A case study on cloud gaming
2011
Cloud computing offers new ways for firms to operate in the global market so that even small firms can compete in markets traditionally dominated by multinational corporations. A case study considers how, over ten years, a small firm developed a successful business model to compete in computer gaming. peerReviewed
Software-as-a-Service Revenue Models
2013
This paper give an overview of the three main revenue models, focusing on the advantages and disadvantages for SaaS providers and their customers. Also identify the most effective revenue model for particular situations.
A Repository for Multirelational Dynamic Networks
2012
Nowadays, WWW contains a number of social media sites, which are growing rapidly. One of the main features of social media sites is to allow to its users creation and modification of contents of the site utilizing the offered WWW interfaces. Such contents are referred to as user generated contents and their type varies from site to site. Social media sites can be modeled as constantly evolving multirelational directed graphs. In this paper we discuss persistent data structures for such graphs, and present and analyze queries performed against the structures. We also estimate the space requirements of the proposed data structures, and compare them with the naive "store each complete snapshot…
E-NAUTILUS: A decision support system for complex multiobjective optimization problems based on the NAUTILUS method
2015
Interactive multiobjective optimization methods cannot necessarily be easily used when (industrial) multiobjective optimization problems are involved. There are at least two important factors to be considered with any interactive method: computationally expensive functions and aspects of human behavior. In this paper, we propose a method based on the existing NAUTILUS method and call it the Enhanced NAUTILUS (E-NAUTILUS) method. This method borrows the motivation of NAUTILUS along with the human aspects related to avoiding trading-off and anchoring bias and extends its applicability for computationally expensive multiobjective optimization problems. In the E-NAUTILUS method, a set of Pareto…
Collaborative EA Information Elicitation Method : The IEM for Business Architecture
2015
This study contributes to the enterprise architecture (EA) methodologies by suggesting a method for eliciting architecture requirements: gathering both the current architecture information, and the development needs and requirements for the business architecture (BA) dimension in EA planning. Most of all EA dimensions, the developing of the BA requires collaboration with various non-IT stakeholders. It presents thus challenges to the IT department, or the consultancy involved in EA related efforts. The contribution of the various stakeholder groups as informants is, however, crucial to well founded EA design decisions. The suggested method takes related IS development fields as starting poi…