A dynamic thermal-hydraulic mathematical model of the evaporator dynamics of a once - through sub critical steam generator was derived and presented. This model allows the investigation of evaporator dynamics including its transient... more
A dynamic thermal-hydraulic mathematical model of the evaporator dynamics of a once - through sub critical steam generator was derived and presented. This model allows the investigation of evaporator dynamics including its transient responses. The evaporator was considered as part of a three-section (economizer, evaporator and super-heater) model with time varying phase boundaries and was described by a set of linearized discrete - difference equations which, with some other algebraic equations, constituted a closed system of equations possible for exact computer solution. This model was derived using the fundamental equations of mass, energy and momentum balance. For the first time, a discrete differential approach was applied in order to investigate such complex, two phase processes. Namely, this approach allows one to escape from the model of this process usually described by a set of partial differential equations and enables one, using this method, to simulate evaporator dynami...
The goal of this work is to examine how second-language learners acquire grammatical knowledge. To measure this knowledge, our research examines how native speakers of English choose between constructions that have similar meanings, but... more
The goal of this work is to examine how second-language learners acquire grammatical knowledge. To measure this knowledge, our research examines how native speakers of English choose between constructions that have similar meanings, but occur in different discourse contexts. An example is the dative alternation (give someone the book vs. give the book to someone). The distribution of these two constructions is explained by a four-factor model that describes the patterns or rules that underlie native-speaker usage. We hypothesized that training examples could be selected to instantiate these four factors in a way that would lead to improved learning of the dative alternation. In addition, we predicted that explicit instruction of the four grammar principles would further enhance learning. Two studies were conducted. Results showed rapid learning and good retention across a week-long delay. Examples that were labeled as “easy” or prototypical by the grammar model were learned faster t...
The purpose of this study is to examine the effects of a model-based introductory physics curriculum on conceptual learning in a Physics First (PF) Initiative. This is the first comparative study in physics education that applies the... more
The purpose of this study is to examine the effects of a model-based introductory physics curriculum on conceptual learning in a Physics First (PF) Initiative. This is the first comparative study in physics education that applies the Rasch modeling approach to examine the effects of a model-based curriculum program combined with PF in the United States. Five teachers and 301 students (in grades 9 through 12) in two mid-Atlantic high schools participated in the study. The students’ conceptual learning was measured by the Force Concept Inventory (FCI). It was found that the ninth-graders enrolled in the model-based program in a PF initiative achieved substantially greater conceptual understanding of the physics content than those 11th-/12th-graders enrolled in the conventional non-modeling, non-PF program (Honors strand). For the 11th-/12th-graders enrolled in the non-PF, non-honors strands, the modeling classes also outperformed the conventional non-modeling classes. The instructional activity reports by students indicated that the model-based approach was generally implemented in modeling classrooms. A closer examination of the field notes and the classroom observation profiles revealed that the greatest inconsistencies in model-based teaching practices observed were related to classroom interactions or discourse. Implications and recommendations for future studies are also discussed.
Collaborative filtering (CF) is popular algorithm for recommender systems. Therefore items which are recommended to users are determined by surveying their communities. CF has good perspective because it can cast off limitation of... more
Collaborative filtering (CF) is popular algorithm for recommender systems. Therefore items which are recommended to users are determined by surveying their communities. CF has good perspective because it can cast off limitation of recommendation by discovering more potential items hidden under communities. Such items are likely to be suitable to users and they should be recommended to users. There are two main approaches for CF: memory-based and model-based. Memory-based algorithm loads entire database into system memory and make prediction for recommendation based on such in-line memory database. It is simple but encounters the problem of huge data. Model-based algorithm tries to compress huge database into a model and performs recommendation task by applying reference mechanism into this model. Model-based CF can response user's request instantly. This paper surveys common techniques for implementing model-based algorithms. We also give a new idea for model-based approach so as to gain high accuracy and solve the problem of sparse matrix by applying evidence-based inference techniques.
The author presents a synthetic overview of recent efforts related to the small area estimation methods applied to the Polish Labor Force Survey (PLFS). The review concerns methodology and results obtained by Central Statistical Office... more
The author presents a synthetic overview of recent efforts related to the small area estimation methods applied to the Polish Labor Force Survey (PLFS). The review concerns methodology and results obtained by Central Statistical Office connected with PLFS and National Census and some results obtained by the author of this paper. In the paper author discusses various methods of estimation together with evaluation of quality of such estimation. In particular the relationship between quality of Bayes estimates type and quality of a priori estimates and also type of applied method of estimation is presented.
UML has become the standard language for modelling in different areas and domains, but it is widely recognized that it lacks support for User Interface Design (UID). On the other hand, ConcurTaskTree (CTT) is one of the most widely used... more
UML has become the standard language for modelling in different areas and domains, but it is widely recognized that it lacks support for User Interface Design (UID). On the other hand, ConcurTaskTree (CTT) is one of the most widely used notations for task and dialogue modelling. An important achievement is the proposed notation and semantics for CTT by extending the UML metamodel, proving that task modelling in user interface design can be accomplished by a UML compliant notation. For the interface structure design was proposed that UML’s CTT could be complemented with Canonical Abstract Prototypes (CAP) leading to a model-based user interface design method co-specified by the presentation (CAP) and behaviour (UML’s CTT) perspectives. In this paper we propose another step in this UID method by defining a specific model compliant with the OMG recommended Model Driven Architecture (MDA), which will be the intermediary between the design model and an implementation of the user interface. This proposal will align the UID method with the MDA recommendation making it possible to automatically generate interface prototypes from conceptual models.
For collaborative applications to be usable, their user interfaces should facilitate the process of sharing information within a group while carrying out common tasks. Currently, the design based on models is one of the most used... more
For collaborative applications to be usable, their user interfaces should facilitate the process of sharing information within a group while carrying out common tasks. Currently, the design based on models is one of the most used techniques that seeks to assure high usability. In user interface design, models can describe and help to analyze abstract interface elements and relationships among them, as well as to guide the implementation using physical components. An approach for designing user interfaces using models at different abstraction levels is presented in this chapter. We also introduce a platform that provides a set of replicated components as a toolkit that facilitates the creation process of groupware user interfaces. In order to apply the proposal, we consider a case study based on a help system for risk operations in financial institutions. Specifically, the proposal aims at guiding the whole development process of user interfaces for collaborative applications.
In Time Correlated Single Photon Counting (TCSPC) the maximum signal throughput is limited by the occurrence of classical pile-up and dead-time effects: At a given photon rate characteristic distortions become visible in the TCSPC... more
In Time Correlated Single Photon Counting (TCSPC) the maximum signal throughput is limited by the occurrence of classical pile-up and dead-time effects: At a given photon rate characteristic distortions become visible in the TCSPC histogram. How to describe these distortions in mathematical terms is well known1,2. While the approach of correcting these distortions directly by operations on the raw data has drawbacks, e.g. with respect to calculation effort as well as numerical stability, it is comparably straightforward to include corrections in the models describing the data. We demonstrate the applicability of a model based approach on decay data which are heavily distorted by dead-time and pile-up effects.
Growing trade volumes and increased security, health and financial control regulations require customs administrations to change their working practices worldwide. An existing dilemma however, is that governments would like on the one... more
Growing trade volumes and increased security, health and financial control regulations require customs administrations to change their working practices worldwide. An existing dilemma however, is that governments would like on the one hand to reduce the administrative burden for businesses and on the other hand to increase security and control. The traditional single side power-posing by customs administrations to trade parties is not appropriate any more. The European Union is now realizing the potential benefits of establishing Customs-and-Business partnerships. To achieve such collaboration, current customs procedures need to be redesigned, and ICT is a key enabler for the redesign. In this paper we present a model-based approach using two levels of abstraction – value and process levels – to support domain experts in investigating how customs procedures can be redesigned while coping with business and administrative challenges. Especially, we focus on a methodological applicatio...
Integrated Safety Systems (ISS), making use of synergy effects from safety-relevant applications distributed across different domains, are currently one of the developing trends in the automotive industry. Such systems require a... more
Integrated Safety Systems (ISS), making use of synergy effects from safety-relevant applications distributed across different domains, are currently one of the developing trends in the automotive industry. Such systems require a dependable fault tolerant in-vehicle electronic architecture. The EASIS consortium, composed of OEMs, sup- pliers and tool producers, is pursuing this goal. In order to meet the high dependability requirements of modern Integrated Safety Systems, the conventional approach is to make use of redundancy in hardware and software. However, to manage redundancy, basic fault tolerance software services are required. With the increasing integration density of functionalities on one ECU, basic software services to monitor and maintain separation of application compo- nents running in parallel as well as to ensure fault containment of corrupted applica- tion components are also required. This paper, as a result of collaboration within the EASIS consortium, describes a...
The aim of this article is to propose a didactical approach to establish appropriate relations between different kinds of chemical knowledge and explanations at the macro and the submicro level. Incorrectly moving between these two levels... more
The aim of this article is to propose a didactical approach to establish appropriate relations between different kinds of chemical knowledge and explanations at the macro and the submicro level. Incorrectly moving between these two levels is regarded as the cause of many misconceptions in school chemistry, and several theoretical frameworks have been proposed to remedy those misconceptions. Our literature review of chemistry education shows that a focus of attention for the macro-submicro interplay problem is put in the relations between observations and inferences; we examine such relations with the aid of ideas from the philosophy of science and the specific philosophy of chemistry. We propose a model-based approach that recognises the continuum between empirical and theoretical, descriptive and explanatory in chemical concepts. Finally, we provide an "exemplary activity" on the topic of gases based on this approach, and we evaluate its suitability in terms of some well-established ideas in didactics of science/chemistry.
