Top-down design of a picture archiving and communications system (PACS) by means of simulation

The development of picture archiving and communications systems (PACS) for medical applications can be regarded as a challenging field in medical informatics. Since 1982, several projects have been started into this direction worldwide. The Dutch IMAGIS (Image Information System) project, started in 1984, is one of them. Within this project, a top-down design strategy is chosen, with the following first steps: (1) A thorough information analysis for a Radiology Department, in which both qualitative and quantitative aspects are included. Such an analysis can be used to estimate the workload on a future PACS system. (2) The construction of a flexible performance prediction tool, based on discrete even simulation. Such a tool can be used to predict the performance of a certain computer system configuration under a certain workload. Based on the information analysis, and using the performance prediction tool, a PACS system is drafted for the thorax section of the Diagnostic Radiology Department of the Leiden University Hospital. In this first design attempt, the assumption was made that current working procedures concerning images will be maintained as much as possible.     

Ergonomics evaluation of picture archiving and communication system implementations in two X-ray departments

Two large X-ray departments in the County of Stockholm have changed from traditional analogue technology to digital imaging, including the implementation of Picture Archiving and Communication Systems (PACS). One of the departments was moved to a completely new purpose-built building and equipped with the latest technology, but for the other one the change merely meant rebuilding and adaptation of existing rooms on the premises. The objectives of the present study were to evaluate the ergonomics effects of the new technique in the two X-ray departments and to find out whether the implementation of digital imaging technique came up to expectations of improved ergonomics and work environment. Another purpose was to compare the outcomes for the two departments, in order to learn about the importance of the different implementation approaches. Questionnaires were sent out to the two departments both before the implementation of PACS and after the transition. The questionnaires covered several aspects of work conditions, such as working time, the physical and psychosocial environment, physical work load and musculoskeletal complaints, expectations from the digital technology, etc. The changeover went better than expected and even high expectations were fulfilled and surpassed. However, there were also some unexpected and distressing results; for example, a substantial increase in headaches and musculoskeletal symptoms as well as the use of pain killers among the radiologists of one of the X-ray departments.     

Forest fire modelling and simulation in the DELTA environment

Traditional simulation methodology supports only changes in models state variables. Some models are better expressed by a combination of both changes in state variables and changes in structure. Dynamic Structure Discrete Event Specification (DSDEVS) is a recently introduced modelling and simulation formalism that provides full support for representing models with time varying structure. The DELTA simulation environment is an implementation of the DSDEVS formalism and provides full support to Structural Simulation. We show the advantages of the Dynamic Structure Cellular Automata describing the model of forest fire spreading and its implementation in the DELTA environment.     

Standard clock simulation and ordinal optimization applied to admission control in integrated communication networks

In this paper we apply the ideas of ordinal optimization and the technique of Standard Clock (SC) simulation to the voice-call admission-control problem in integrated voice/data multihop radio networks. This is an important problem in networking that is not amenable to exact analysis by means of the usual network modeling techniques. We first describe the use of the SC approach on sequential machines, and quantify the speedup in simulation time that is achieved by its use in a number of queueing examples. We then develop an efficient simulation model for wireless integrated networks based on the use of the SC approach, which permits the parallel simulation of a large number of admission-control policies, thereby reducing computation time significantly. This model is an extension of the basic SC approach in that it incorporates fixed-length data packets, whereas SC simulation is normally limited to systems with exponentially distributed interevent times. Using this model, we demonstrate the effectiveness of ordinal-optimization techniques, which provide a remarkably good ranking of admission-control policies after relatively short simulation runs, thereby facilitating the rapid determination of good policies. Moreover, we demonstrate that the use of crude, inaccurate analytical and simulation models can provide highly accurate policy rankings that can be used in conjunction with ordinal-optimization methods, provided that they incorporate the key aspects of system operation.     

Stability of the backward differentiation formula (FIRM) applied to electrochemical digital simulation

The stability, in the von Neumann sense, of the backward differentiation formula (BDF) or FIRM algorithm for electrochemical digital simulation as a function of the number of time levels k, was studied. As with ordinary differential equations, for the single (partial differential) diffusion-reaction equation examined it was found that the method becomes unstable for k > 7 (i.e. order > 6). This result was confirmed by some example simulations.     

Modeling and analyzing a physician clinic environment using discrete-event (visual) simulation

This paper examines the design and development of a discrete-event (visual) simulation model of a physician clinic environment within a physician network. Biological & Popular Culture, Inc. (Biopop) sought to partner with healthcare professionals to provide high-quality, cost-effective medical care within a physician network setting. Towards this end, a discrete-event (visual) simulation model that captures both the operations of a family practice healthcare clinic and a centralized information center is presented. The research presented in this article focuses on the family practice healthcare clinic. This simulation model is built in an object-oriented, visual manner utilizing the visual simulation environment (VSE). Application of the object-oriented paradigm (OOP) allows simulation objects in the model to be easily reused. The simulation model provides a tool for risk-free evaluation of operating policies in the clinical environment. Results of a fractional factorial design to determine those input factors which significantly affect overall clinic effectiveness are reported.Scope and purposeWith increased pressures from governmental and insurance agencies, today's physician devotes less time to patient care and more time to administration. To alleviate this problem, Biological & Popular Culture, Inc. (Biopop) proposed the building of partnerships with healthcare professionals to provide high-quality, cost-effective medical care in a physician network setting. The proposed physician network is to be composed of clinics (i.e., outpatient medical facilities where patient care is delivered) located throughout the United States. Member clinics would benefit from centrally managed non-medical operations and business consultation from Biopop. Biopop's overall goal is to increase patient flow and customer satisfaction in the clinical environment.To assist Biopop in evaluating potential operating procedures, a discrete-event simulation model has been constructed. The model is built in an object-oriented, visual manner utilizing Orca Computer, Inc.'s visual simulation environment (VSE). The model examines both internal Biopop operations and external clinic operations. The research presented herein describes how the simulation model was designed and built, including the verification, validation, and testing procedures applied. Results of simulation experiments run on the clinical environment using the simulation model are also reported. The results of these computer runs suggest ways in which healthcare clinics can be redesigned, without sacrificing service levels or profitability of the facility.     

Development and evaluation of a compartmental picture archiving and communications system model for integration and visualization of multidisciplinary biomedical data to facilitate student learning in an integrative health clinic

Information technology (IT) has the potential to improve the clinical learning environment. The extent to which IT enhances or detracts from healthcare professionals’ role performance can be expected to affect both student learning and patient outcomes. This study evaluated nursing students’ satisfaction with a novel compartmental Picture Archiving and Communications System (PACS) for the automatic object-oriented integration and visualization of heterogeneous biomedical data. The compartmental PACS was specially designed to support client assessment and clinical education in the integrative health clinic of a university, which is run by a multidisciplinary service team. The sample was 63 nursing students, who were asked to complete a series of realistic tasks using the compartmental PACS. Upon completing the tasks, the Computer System Usability Questionnaire (CSUQ) was administered to assess their satisfaction with the system. Results from data analysis showed that nursing students who completed the evaluation had a satisfactory experience with the system. The Information Quality subscale mean was the highest mean of the CSUQ subscales. This is an important finding as the multidisciplinary data visualization feature of the system provides a technology-enhanced learning environment that can support nursing students’ efforts to both organize and represent knowledge. Through the compartmental PACS, students are assisted in connecting relevant knowledge via various representations of medical data for the clinical conditions under study.     

An approach for modelling a clearance revolute joint with a constantly updating wear profile in a multibody system: simulation and experiment

Multibody System Dynamics - An approach for modelling a clearance revolute joint with a constantly updating wear profile in a multibody system is proposed. Before the contact analysis, the...     

Characteristics and diffusion of a microcomputer geoprocessing system: The Urban Data Management Software (UDMS) package

This paper presents a microcomputer software package for spatial modeling and traces its diffusion throughout the world. We consider its diffusion as a study in infrastructure constrained diffusion. One of the major conclusions is that the spread of increasingly low-cost microcomputers provides a necessary, but insufficient, infrastructure for the development and diffusion of spatial modeling activities.     

Interactive fruit panel (IFP): a tangible serious game for children with special needs to learn an alternative communication system

Universal Access in the Information Society - After several months working with Mateo, a child with special needs, the therapist of the Early Childhood Treatment Center (ECTC) was astonished by how...     

First Arrival Seismic Tomography (FAST) vs. PStomo_eq applied to crooked line seismic data from the Siljan ring area

When seismic profiles deviate significantly from straight lines, the results from 2D traveltime inversion programs will be in error due to the inherent 3D component present in the data. Thus, it is necessary to use a program that can handle the 3D aspects of the acquisition geometry. This study compares the performance and results from two computer programs for 3D seismic tomography. These algorithms are the package for First Arrival Seismic Tomography (FAST) and a Local Earthquake tomography program, PStomo_eq. Although both codes invert for the velocity field using the conjugate gradient solver LSQR, the common smoothness constraint is handled differently. In addition, the programs do not incorporate the same options for user-specified constraints. These differences in implementation are clearly observed in the inverted velocity fields obtained in this study. Both FAST and PStomo_eq are applied to synthetic and real data sets with crooked line geometry. First arrival traveltimes from seismic data acquired in the Siljan ring impact area are used for the real data set test. The results show that FAST gives smoother models than PStomo_eq. On the real data set PStomo_eq showed a better correlation to the information at hand. Different criteria exist for what is desirable in a model; thus, the choice of which program to use will mostly depend on the particular goals of the study.     

Spectral estimates in Fourier spectroscopy applied to remote sensing of the atmosphere: a parametric autoregressive modelling approach

Abstract

A procedure to recover high resolution spectra without any intervening window from infrared Fourier spectrometer data is presented. The technique relies on the maximum entropy principle in information theory. A parametric autoregressive modelling approach is used. Numerical examples are carried using synthetic spectra computed by an high resolution radiative transfer code. The effect of additive noise is also analysed. The application of the technique to remote sensing of the atmosphere is discussed.     

Modeling and inference for troubleshooting with interventions applied to a heavy truck auxiliary braking system

Computer assisted troubleshooting with external interventions is considered. The work is motivated by the task of repairing an automotive vehicle at lowest possible expected cost. The main contribution is a decision theoretic troubleshooting system that is developed to handle external interventions. In particular, practical issues in modeling for troubleshooting are discussed, the troubleshooting system is described, and a method for the efficient probability computations is developed. The troubleshooting systems consists of two parts; a planner that relies on AO^? search and a diagnoser that utilizes Bayesian networks (BN). The work is based on a case study of an auxiliary braking system of a modern truck. Two main challenges in troubleshooting automotive vehicles are the need for disassembling the vehicle during troubleshooting to access parts to repair, and the difficulty to verify that the vehicle is fault free. These facts lead to that probabilities for faults and for future observations must be computed for a system that has been subject to external interventions that cause changes in the dependency structure. The probability computations are further complicated due to the mixture of instantaneous and non-instantaneous dependencies. To compute the probabilities, we develop a method based on an algorithm, updateBN, that updates a static BN to account for the external interventions.     

A recommender system applied to the indirect materials selection process (RS-IMSP) for producing automobile spare parts

In this work, the development of a recommender system that aims to facilitate the indirect materials selection task for the creation of spare parts is proposed. In the industrial sector there are spare parts manufacturing companies, where there is a high rotation of staff and this leads to loss of knowledge as new users do not know what indirect materials they should select in the warehouse to create certain parts. The proposed system aims to integrate an indirect materials recommender system to assist this warehouse task. The proposed system is based on the non-personalized approach and similar order circumstances, to perform the recommendation process. From the evaluation of the proposed system, we could conclude that the indirect materials selection process for producing auto parts was improved.