A new perspective for discrete-time models of a continuous-timesystem

Various discrete-time models of a continuous-time system are given an interpretation in terms of the system structures and the hold device. This concept provides a novel perspective of various discrete-time models and a simple way to understand the relationships which exist among those models, but which are not easily visualized without the proposed interpretation. This interpretation of discrete-time models also allows the creation of new types of models. Tables of discrete-time models, including the newly developed ones, are provided     

A uniform approach for access control and business models with explicit rule realization

Access control is an important part of security in software, such as business applications, since it determines the access of users to objects and operations and the constraints of this access. Business and access control models are expressed using different representations. In addition, access control rules are not generally defined explicitly from access control models. Even though the business model and access control model are two separate modeling abstractions, they are inter-connected as access control is part of any business model. Therefore, the first goal is to add access control models to business models using the same fundamental building blocks. The second goal is to use these models and define general access control rules explicitly from these models so that the connection between models and their realizations are also present. This paper describes a new common representation for business models and classes of access control models based on the Resource–Event–Agent (REA) modeling approach to business models. In addition, the connection between models and their represented rules is clearly defined. We present a uniform approach to business and access control models. First, access control primitives are mapped onto REA-based access control patterns. Then, REA-based access control patterns are combined to define access control models. Based on these models, general access control rules are expressed in Extended Backus–Naur Form.     

Studies in the theory of algebraic models of programs with procedures

Algebraic models of programs with procedures extend algebraic models of programs that are free of procedures (simple models of programs). A specific feature of both types of models is that they are built for some formalization of software programs. Models of programs are intended for studying functional equivalence of formalized programs and constructing wide sets of equivalent transformations of programs. Two basic problems in the theory of algebraic models of programs are the equivalence problem and the problem of building complete systems of equivalent transformations. An increasing interest in models of programs with procedures is due to the abundance of results obtained for simple models of programs. The most suitable model of programs with procedures is a gateway model. A remarkable feature of these models is that every such model is induced by some simple model of programs. This paper gives a survey of the latest results obtained for gateway models of programs.     

Designing business capability-aware configurable process models

Process Aware Information Systems manage processes within organisations on the basis of business process models. These models can be created either from scratch or by reusing exiting reference process models.Particular types of reference models are configurable process models that are created by merging multiple models into a single one that can be customized to the needs of the business experts. Using those models presents two main challenges: their creation and their configuration.In this paper, we focus on the first challenge and propose a novel algorithm for merging process models into a configurable process model. The difference in our work is the pre-annotated process models with their business capabilities that report on what actions each process element achieves. Our algorithm generates configurable models that are also annotated with their capabilities that can be used to face the second challenge of these models: the configuration phase.We tested our algorithm using real-world process models to evaluate the required creation time and resulting compression rate after merging the input models. The results show that the models can be created in few milliseconds and achieving a compression rate of 50%. We further carried out interviews with domain experts to assess the usefulness and the level of maturity of this work. The results show the importance of the automation of process merging using a tool support that we proposed. However, further adaptation efforts are required to integrate this work in the working environments of the interviewed experts.     

Variations of the matrix models

The matrix models of [6] are parallel sequential generative models generating two dimensional rectangular arrays. Here we change the definition of matrix models a-little and define extended matrix models which generate arrays not necessarily rectangular. The effect of placing a control on these models is studied. The corresponding automata are defined by combining a finite number of FSA which can be live or dead, active or idle, with a FSA, PDA, LBA or TM. Several other variations of the matrix models are also introduced and Shown to generate interesting classes of pictures with suitable control.     

信息检索的概率模型

The study of mathematical models on information retrieval is an important area in the Information Retrieval community. Because of the uncertainty characteristic of IR,the probability model based on statistical probability is apromising model from recent to future. Those models can be classified into classical models and probability network models. Several famous models are introduced and their shortcomings are pointed out in this paper. We also clarifythe relationship of these models and introduce a new models based on statistical language model curtly.     

Dual models for possibilistic regression analysis

Upper and lower regression models (dual possibilistic models) are proposed for data analysis with crisp inputs and interval or fuzzy outputs. Based on the given data, the dual possibilistic models can be derived from upper and lower directions, respectively, where the inclusion relationship between these two models holds. Thus, the inherent uncertainty existing in the given phenomenon can be approximated by the dual models. As a core part of possibilistic regression, firstly possibilistic regression for crisp inputs and interval outputs is considered where the basic dual linear models based on linear programming, dual nonlinear models based on linear programming and dual nonlinear models based on quadratic programming are systematically addressed, and similarities between dual possibilistic regression models and rough sets are analyzed in depth. Then, as a natural extension, dual possibilistic regression models for crisp inputs and fuzzy outputs are addressed.     

Studying just-in-time defect prediction using cross-project models

Unlike traditional defect prediction models that identify defect-prone modules, Just-In-Time (JIT) defect prediction models identify defect-inducing changes. As such, JIT defect models can provide earlier feedback for developers, while design decisions are still fresh in their minds. Unfortunately, similar to traditional defect models, JIT models require a large amount of training data, which is not available when projects are in initial development phases. To address this limitation in traditional defect prediction, prior work has proposed cross-project models, i.e., models learned from other projects with sufficient history. However, cross-project models have not yet been explored in the context of JIT prediction. Therefore, in this study, we empirically evaluate the performance of JIT models in a cross-project context. Through an empirical study on 11 open source projects, we find that while JIT models rarely perform well in a cross-project context, their performance tends to improve when using approaches that: (1) select models trained using other projects that are similar to the testing project, (2) combine the data of several other projects to produce a larger pool of training data, and (3) combine the models of several other projects to produce an ensemble model. Our findings empirically confirm that JIT models learned using other projects are a viable solution for projects with limited historical data. However, JIT models tend to perform best in a cross-project context when the data used to learn them are carefully selected.     

On a class of algebraic models of programs of practical interest

Algebraic program models are designed for the study of the semantic properties of programs on models—program schemas. The design concepts of these models are presented, and a class of models is considered that approximate real sequential programs. Algorithms are constructed that recognize the equivalence of program schemas in models of a given class with practically acceptable complexity. The validity of these algorithms for constructing equivalent transformations (ETs) of program schemas is established.     

Anatomical and dynamic volume spline model applied to facial soft tissue

Biomechanical modeling of soft tissue is a complex problem for achieving realistic surgical simulations, surgical planning, and scientific analysis. In the literature, three categories of biomechanical models: spline based models, spring models, and finite element models (FEMs) are mainly used for dealing with this problem. Among these, spline based models offer relatively fast and realistic soft tissue simulations by utilizing both the spring and FEMs. In this paper, a new dynamic volume spline model for human face skin is proposed and the performance of our model is discussed by estimating the results of facial surgery of three different patients. Face models of the patients are obtained from 3D CT/MR scans by segmenting the skull, muscle, and skin layers. In these face models, the skull and the muscle layers are considered as the rigid boundary for the skin layer and the skin layer is modeled by our dynamic volume spline. The control points of the dynamic volume spline are localized masses with viscoelastic material properties (stiffness, damping, and mass). These parameters are computed from the skin material properties that were published in the literature. Once the face models are generated, facial surgery plannings are simulated. Infact, the pre‐surgery face models are modified according to the surgical plans and the estimated post‐surgery face models are compared with the actual post‐surgery face models. Moreover, in order to discuss the performance of our dynamic volume spline model, the same analyses are performed on the post‐surgery estimations of a conventional tool. Copyright © 2011 John Wiley & Sons, Ltd.     

Exact maximum likelihood estimation for non-stationary periodic time series models

Time series models with parameter values that depend on the seasonal index are commonly referred to as periodic models. Periodic formulations for two classes of time series models are considered: seasonal autoregressive integrated moving average and unobserved components models. Convenient state space representations of the periodic models are proposed to facilitate model identification, specification and exact maximum likelihood estimation of the periodic parameters. These formulations do not require a priori (seasonal) differencing of the time series. The time-varying state space representation is an attractive alternative to the time-invariant vector representation of periodic models which typically leads to a high dimensional state vector in monthly periodic time series models. A key development is our method for computing the variance-covariance matrix of the initial set of observations which is required for exact maximum likelihood estimation. The two classes of periodic models are illustrated for a monthly postwar US unemployment time series.     

Nature-inspired optimal tuning of input membership functions of Takagi-Sugeno-Kang fuzzy models for Anti-lock Braking Systems

This paper suggests a synergy of fuzzy logic and nature-inspired optimization in terms of the nature-inspired optimal tuning of the input membership functions of a class of Takagi-Sugeno-Kang (TSK) fuzzy models dedicated to Anti-lock Braking Systems (ABSs). A set of TSK fuzzy models is proposed by a novel fuzzy modeling approach for ABSs. The fuzzy modeling approach starts with the derivation of a set of local state-space models of the nonlinear ABS process by the linearization of the first-principle process model at ten operating points. The TSK fuzzy model structure and the initial TSK fuzzy models are obtained by the modal equivalence principle in terms of placing the local state-space models in the rule consequents of the TSK fuzzy models. An operating point selection algorithm to guide modeling is proposed, formulated on the basis of ranking the operating points according to their importance factors, and inserted in the third step of the fuzzy modeling approach. The optimization problems are defined such that to minimize the objective functions expressed as the average of squared modeling errors over the time horizon, and the variables of these functions are a part of the parameters of the input membership functions. Two representative nature-inspired algorithms, namely a Simulated Annealing (SA) algorithm and a Particle Swarm Optimization (PSO) algorithm, are implemented to solve the optimization problems and to obtain optimal TSK fuzzy models. The validation and the comparison of SA and PSO and of the new TSK fuzzy models are carried out for an ABS laboratory equipment. The real-time experimental results highlight that the optimized TSK fuzzy models are simple and consistent with both training data and validation data and that these models outperform the initial TSK fuzzy models.     

虚拟游戏场景中的模型研究

游戏游戏建筑模型是虚拟虚拟游戏模型中的基本对象,已有的对游戏建筑的表示局限于某一层次级别,比如块模型、带屋顶的模型、结构模型和室内模型.引入了连续层次级别这一概念来对地理信息系统中的建筑进行表示和建模,而连续层次级别方法统一了虚拟三维游戏模型中不同类型的建筑的表示.     

Linear, Branching Time and Joint Closure Semantics for Temporal Logic

Temporal logic can be used to describe processes: their behaviour ischaracterized by a set of temporal models axiomatized by a temporaltheory. Two types of models are most often used for this purpose: linearand branching time models. In this paper a third approach, based onsocalled joint closure models, is studied using models which incorporateall possible behaviour in one model. Relations between this approach andthe other two are studied. In order to define constructions needed torelate branching time models, appropriate algebraic notions are defined(in a category theoretical manner) and exploited. In particular, thenotion of joint closure is used to construct one model subsuming a setof models. Using this universal algebraic construction we show that aset of linear models can be merged to a unique branching time model.Logical properties of the described algebraic constructions are studied.The proposed approach has been successfully aplied to obtain anappropriate semantics for non-monotonic reasoning processes based ondefault logic. References are discussed that show the details of theseapplications.     

自然语言处理中的模型

本文简单介绍了自然语言处理发展的现状,讨论了自然语言处理模型,将其分为三大类：分析模型、统计模型及混合模型。具体介绍了分析模型原理及存在的问题,重点讨论了各种统计模型的特点及局限性,最后简单介绍了混合模型,并指出目前自然语言处理技术中存在的问题。     

A review of models for low impact urban stormwater drainage

Low-impact development urban stormwater drainage systems (LID) are an increasingly popular method to reduce the adverse hydrologic and water quality effects of urbanisation. In this review, ten existing stormwater models are compared in relation to attributes relevant to modelling LID. The models are all based on conventional methods for runoff generation and routing, but half of the models add a groundwater/baseflow component and several include infiltration from LID devices. The models also use conventional methods for contaminant generation and treatment such as buildup-washoff conceptual models and first order decay processes, although some models add treatment mechanisms specific to particular types of LID device. Several models are capable of modelling distributed on-site devices with a fine temporal resolution and continuous simulation, yet the need for such temporal and spatial detail needs to be established. There is a trend towards incorporation of more types of LID into stormwater models, and some recent models incorporate a wide range of LID devices or measures. Despite this progress, there are many areas for further model development, many of which relate to stormwater models in general, including: broadening the range of contaminants; improving the representation of contaminant transport in streams and within treatment devices; treating baseflow components and runoff from pervious surfaces more thoroughly; linkage to habitat and toxicity models; linkage to automated calibration and prediction uncertainty models; investigating up-scaling for representation of on-site devices at a catchment level; and catchment scale testing of model predictions.     

On the use of software design models in software development practice: An empirical investigation

Research into software design models in general, and into the UML in particular, focuses on answering the question how design models are used, completely ignoring the question if they are used. There is an assumption in the literature that the UML is the de facto standard, and that use of design models has had a profound and substantial effect on how software is designed by virtue of models giving the ability to do model-checking, code generation, or automated test generation. However for this assumption to be true, there has to be significant use of design models in practice by developers.This paper presents the results of a survey summarizing the answers of 3785 developers answering the simple question on the extent to which design models are used before coding. We relate their use of models with (i) total years of programming experience, (ii) open or closed development, (iii) educational level, (iv) programming language used, and (v) development type.The answer to our question was that design models are not used very extensively in industry, and where they are used, the use is informal and without tool support, and the notation is often not UML. The use of models decreased with an increase in experience and increased with higher level of qualification. Overall we found that models are used primarily as a communication and collaboration mechanism where there is a need to solve problems and/or get a joint understanding of the overall design in a group. We also conclude that models are seldom updated after initially created and are usually drawn on a whiteboard or on paper.     

Knowledge Engineering for Rough Sets Based Decision‐Making Models

In this paper, a review of decision‐making models based on the rough set theory is presented. The use of these techniques allows for the presence of uncertainty in computer models that are developed for decision making, and to formulate the decision‐making models using the experiences of previous decisions made. Since the formulation of these models differs from the classical approach of decision‐making models, in this paper, the models are analyzed and a method is proposed for its implementation.