Semi-physical mean-value NOx model for diesel engine control

A semi-physical model has been developed to predict nitrogen oxide (NO_x) emissions produced by diesel engines. This model is suitable for online NO_x estimation and for model-based engine control. It is derived from a zero-dimensional thermodynamic model which was simplified by only retaining main phenomena contributing to NO_x formation. The crank angle evolution of the burned gas temperature, which has a strong impact on NO_x formation rate, is described by a semi-empirical model whose key variable is the maximum burned gas temperature. This variable presents a good correlation with the molar fraction of NO_x at the end of combustion and can be expressed as a function of the intake burned gas ratio and the start of combustion. The maximum burned gas temperature sub-model is then coupled to an averaged NO_x formation kinetic model (based on the Zeldovich mechanism) to form a mean-value model for NO_x computation. This latter model was validated using data sets recorded in two diesel engines for steady-state operating conditions as well as for several driving cycles including parametric variations of the engine calibration.     

A reference model for team-enabled workflow management systems

Today's workflow systems assume that each work item is executed by a single worker. From the viewpoint of the system, a worker with the proper qualifications selects a work item, executes the associated work, and reports the result. There is usually no support for teams, i.e., groups of people collaborating by jointly executing work items (e.g., the program committee of a conference, the management team of a company, a working group, and the board of directors). In this paper, we propose the addition of a team concept to today's workflow management systems. Clearly, this involves a marriage of workflow and groupware technology. To shed light on the introduction of teams, we extend the traditional organizational meta model with teams and propose a team-enabled workflow reference model. For this reference model and to express constraints with respect to the distribution of work to teams, we use object constraint language (OCL).     

Optimal energy management for a diesel hybrid electric vehicle considering transient PM and quasi-static NOx emissions

In this paper, optimal energy management strategies are derived to balance fuel consumption, raw particulate matter (PM) emissions, and raw nitrogen oxide (NOx) emissions for a Diesel hybrid electric vehicle. Two methods for the derivation of these strategies are compared. One method is based on dynamic programming and steady-state engine maps only. The second method is based on dynamic programming, steady-state engine maps, and a validated transient PM emission model. As a result, only the second method allows for the generation of smooth engine set point trajectories to reduce transient PM emissions without compromising fuel consumption and NOx emissions.     

Development and experimental studies of a control-oriented SCR model for a two-catalyst urea-SCR system

This paper presents the development and experimental studies of a complete selective catalytic reduction (SCR) system control-oriented model of a two-catalyst SCR system with onboard NO_x and ammonia sensors. SCR catalysts have been popularly regarded as effective means for NO_x emission control in medium- and heavy-duty vehicles in recent years. However, control of urea dosing upstream of the SCR systems still remains a challenge in the field mainly due to the complicated SCR dynamics and limited/inaccurate feedback information. A control-oriented SCR model is thus indispensable for SCR control systems. A variety of experimental tests were examined using a Diesel engine-aftertreatment system consisting of a diesel oxidation catalyst (DOC)/diesel particulate filter (DPF), two-SCR catalysts (Fe-Zeolite type) in series, three NO_x sensors, and two NH₃ sensors. By utilizing multiple emission sensors and the two-catalyst SCR setup, the sensor properties and SCR system dynamics were studied. Grounded in the experimental investigations and the physical insights, a control-oriented model for a complete SCR system was developed and validated with experimental data.     

GenTrust: A genetic trust management model for peer-to-peer systems

In recent years, peer-to-peer systems have attracted significant interest by offering diverse and easily accessible sharing environments to users. However, this flexibility of P2P systems introduces security vulnerabilities. Peers often interact with unknown or unfamiliar peers and become vulnerable to a wide variety of attacks. Therefore, having a robust trust management model is critical for such open environments in order to exclude unreliable peers from the system. In this study, a new trust model for peer-to-peer networks called GenTrust is proposed. GenTrust has evolved by using genetic programming. In this model, a peer calculates the trustworthiness of another peer based on the features extracted from past interactions and the recommendations. Since the proposed model does not rely on any central authority or global trust values, it suits the decentralized nature of P2P networks. Moreover, the experimental results show that the model is very effective against various attackers, namely individual, collaborative, and pseudospoofing attackers. An analysis on features is also carried out in order to explore their effects on the results. This is the first study which investigates the use of genetic programming on trust management.     

Mass flow estimation with model bias correction for a turbocharged Diesel engine

A systematic design method for mass flow estimation with correction for model bias is proposed. Based on an augmented observable Mean Value Engine Model (MVEM) of a turbocharged Diesel engine, the online estimation of states with additional biases is performed to compute the mass flows for different places. A correction method is applied, that utilizes estimated biases which are in a least-square sense redistributed between the correction terms to the uncertain mass flow maps and then added to the estimated mass flows. An Extended Kalman Filter (EKF) is tested off-line on production car engine data where the combination of an intake manifold pressure sensor, exhaust manifold pressure sensor and turbocharger speed sensor is compared and discussed in different sensor fusions. It is shown that the correction method improves the uncorrected estimated air mass flow which is validated against the airflow data measured in the intake duct.     

Validation of an evaluation model for learning management systems

Abstract   This study aims to validate a model for evaluating learning management systems (LMS) used in e-learning fields. A survey of 163 e-learning experts, regarding 81 validation items developed through literature review, was used to ascertain the importance of the criteria. A concise list of explanatory constructs, including two principle factors, was extracted from the responses of 133 respondents by exploratory factor analysis. Factor I was labeled as 'instruction management, screen design, and technology' and factor II, 'interaction and evaluation'. Factors I and II consisted of four and three sub-factors, respectively. Confirmatory factor analysis, in turn, was carried out to assess the degree to which the plausibility of factor models was empirically confirmed. Overall fit measures (RMSEA, CFI, NNFI indexes) showed the model to be quite suitable for LMS evaluation. Reliability estimates using Cronbach's alpha indicated that the evaluation tool had good internal consistency. The overall results of the analyses suggest that this evaluation tool is highly instrumental for LMS.     

Comparison criteria for GDMO-based network management information models: A step towards the integration of management systems

The integration of Management Information Bases (MIBs) is one of the challenges of integrated network management. This is made more difficult by the existence of many different ways for structuring the MIB and defining managed objects. This paper addresses the issue of integrating GDMO-based MIBs created on the basis of different Management Information Models (MIMs). Three MIMs (NMF Library Release 1. 1, ITU-T M. 3100 and ETSI GOM) are analyzed with the help of a simple network configuration, and some MIM comparison criteria are proposed. The criteria can be used to assess the dificulty of integrating MIBs based on those models.     

基于KULI的发动机热管理瞬态模型的参数设置与仿真

以某重型柴油机为原型,利用KULI软件建立了发动机冷却系统模型,阐述了模型中发动机参数的设置原理,进行了瞬态工况下冷却液温度以及润滑油温度变化的仿真。结果说明：其仿真结果与实验数值吻合较好,模型精度可靠,模型中发动机的参数设置原理为发动机热管理瞬态模型的设置提供了一种方法,使用该方法可用来设置不同类型的发动机,为发动机热管理系统的仿真计算提供较为准确的放热边界条件,并进一步用来仿真完整的发动机热管理系统。     

An integrated trust and reputation model for open multi-agent systems

Trust and reputation are central to effective interactions in open multi-agent systems (MAS) in which agents, that are owned by a variety of stakeholders, continuously enter and leave the system. This openness means existing trust and reputation models cannot readily be used since their performance suffers when there are various (unforseen) changes in the environment. To this end, this paper presents FIRE, a trust and reputation model that integrates a number of information sources to produce a comprehensive assessment of an agent’s likely performance in open systems. Specifically, FIRE incorporates interaction trust, role-based trust, witness reputation, and certified reputation to provide trust metrics in most circumstances. FIRE is empirically evaluated and is shown to help agents gain better utility (by effectively selecting appropriate interaction partners) than our benchmarks in a variety of agent populations. It is also shown that FIRE is able to effectively respond to changes that occur in an agent’s environment.     

Coupling excavator hydraulic system and internal combustion engine models for the real-time simulation

Rising energy costs and emissions restrictions force manufacturers to exploit new techniques to reduce fuel consumption and pollutant production. Many solutions have been proposed for off-road vehicles, mainly based on reduction of hydraulic losses, better control strategies and introduction of hybrid architectures. In these applications the optimisation of the matching between hydraulic system and thermal engine is a major concern to improve system overall efficiency. The work presented in the paper is focused on the development of a method for the simulation of typical mobile machinery where hydraulic systems are powered by internal combustion engines; the proposed co-simulation approach can be useful in the development cycle of this machinery.     

Measures of success for lone-user management support systems

Abstract. Management support sytems (MSS) are systems that involve the use of information technologies to support management lone-user MSS are such systems used by managers acting alone, whether the systems have been developed for an individual's exclusive use or for more than one user. Information systems research has been hampered by the lack of widely agreed measures of success. There are two main reasons for this. First, there has been a lack of rigour in the presentation of research findings, particularly in the definition of the types of system that have been investigated. This is particularly the case with MSS. Second, there is often no direct way of determining the effect of an MSS on the goals of an organization in the midst of many other concurrent factors. A classification of lone-user MSS is first given. The many, often indirect, measures of success that have been suggested are then charted. These are then incorporated into a hierarchical framework of organizational goals and intra-MSS measures. Finally, appropriate measures of success to use with the two major classes of MSS are suggested.     

Dynamic adaptation of response-time models for QoS management in autonomic systems

In transactional systems, the objectives of quality of service regarding are often specified by Service Level Objectives (SLOs) that stipulate a response time to be achieved for a percentile of the transactions. Usually, there are different client classes with different SLOs. In this paper, we extend a technique that enforces the fulfilment of the SLOs using admission control. The admission control of new user sessions is based on a response-time model. The technique proposed in this paper dynamically adapts the model to changes in workload characteristics and system configuration, so that the system can work autonomically, without human intervention. The technique requires no knowledge about the internals of the system; thus, it is easy to use and can be applied to many systems. Its utility is demonstrated by a set of experiments on a system that implements the TPC-App benchmark. The experiments show that the model adaptation works correctly in very different situations that include large and small changes in response times, increasing and decreasing response times, and different patterns of workload injection. In all this scenarios, the technique updates the model progressively until it adjusts to the new situation and in intermediate situations the model never experiences abnormal behaviour that could lead to a failure in the admission control component.     

Towards an evaluation framework for knowledge management systems

In this paper we develop an evaluation framework for Knowledge Management Systems (KMS). The framework builds on the theoretical foundations underlying organizational Knowledge Management (KM) to identify key KM activities and the KMS capabilities required to support each activity. These capabilities are then used to form a benchmark for evaluating KMS. Organizations selecting KMS can use the framework to identify gaps and overlaps in the extent to which the capabilities provided and utilized by their current KMS portfolio meet the KM needs of the organization. Other applications of the framework are also discussed.

Information systems management and strategy formulation: the 'stages of growth' model revisited

Abstract. The original 'stages of growth' model, as applied to the field of Information Systems (Gibson & Nolan, 1974), may be viewed as seminal, given the influence it has had on both theory and practice (Nolan, 1984; Sullivan, 1985; Ward, et al., 1990). This is so, despite the model's lack of substantiation based on empirical evidence, the overly simplistic assumptions on which it is based, and the limited focus of the original concept (Benbasat, et al., 1984; King & Kraemer, 1984).
Since its first appearance, the model has been refined following many applications (Nolan, 1979, 1984). In addition, others have developed 'stages of growth' models of their own. For example, Somogyi & Galliers, (1987a, b)provide a model depicting the move from basic data processing systems to strategic information systems, tracing the early days of commercial applications of computing through to the present day (Ward et al. 1990). Earl (1983, 1986, 1988, 1989) proposes a stages-model for information systems planning, as does Bhabuta (1988), while Hirschheim, et al. (1988) have developed a more broadly focused model associated with the development of the information-systems management function.
As a result of a review of the above and of a case study research undertaken in Perth, Western Australia, a revised model was developed, which takes account of current thinking and past experience in the application of the various 'stages of growth' models (Sutherland & Galliers, 1989).
This paper sets out to review some of these models and proceeds to describe the process of developing, testing and applying the revised 'stages of growth' model. The model is more broadly focused than the original concept, incorporating strategic, organizational, human resource and management considerations. As a result, it is argued that this model has greater utility than its predecessors.     

Periodic input estimation for linear periodic systems: Automotive engine applications

In this paper, we consider periodic linear systems driven by T₀-periodic signals that we desire to reconstruct. The systems under consideration are of the form , y=C(t)x, x∈Rⁿ, w∈R^m, y∈R^p, (m?p?n) where A(t), A₀(t), and C(t) are T₀-periodic matrices. The period T₀ is known. The T₀-periodic input signal w(t) is unknown but is assumed to admit a finite dimensional Fourier decomposition. Our contribution is a technique to estimate w from the measurements y. In both full state measurement and partial state measurement cases, we propose an efficient observer for the coefficients of the Fourier decomposition of w(t). The proposed techniques are particularly attractive for automotive engine applications where sampling time is short. In this situation, standard estimation techniques based on Kalman filters are often discarded (because of their relative high computational burden). Relevance of our approach is supported by two practical cases of application. Detailed convergence analysis is also provided. Under standard observability conditions, we prove asymptotic convergence when the tuning parameters are chosen sufficiently small.