| 1. |
- Aakjær, Mia, et al.
(författare)
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Surveillance of Antidepressant Safety (SADS) : Active Signal Detection of Serious Medical Events Following SSRI and SNRI Initiation Using Big Healthcare Data
- 2021
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Ingår i: Drug Safety. - : Springer. - 0114-5916 .- 1179-1942. ; 44, s. 1215-1230
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Tidskriftsartikel (refereegranskat)abstract
- Introduction The current process for generating evidence in pharmacovigilance has several limitations, which often lead to delays in the evaluation of drug-associated risks.Objectives In this study, we proposed and tested a near real-time epidemiological surveillance system using sequential, cumulative analyses focusing on the detection and preliminary risk quantification of potential safety signals following initiation of selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs).Methods We emulated an active surveillance system in an historical setting by conducting repeated annual cohort studies using nationwide Danish healthcare data (1996–2016). Outcomes were selected from the European Medicines Agency's Designated Medical Event list, summaries of product characteristics, and the literature. We followed patients for a maximum of 6 months from treatment initiation to the event of interest or censoring. We performed Cox regression analyses adjusted for standard sets of covariates. Potential safety signals were visualized using heat maps and cumulative hazard ratio (HR) plots over time.Results In the total study population, 969,667 new users were included and followed for 461,506 person-years. We detected potential safety signals with incidence rates as low as 0.9 per 10,000 person-years. Having eight different exposure drugs and 51 medical events, we identified 31 unique combinations of potential safety signals with a positive association to the event of interest in the exposed group. We proposed that these signals were designated for further evaluation once they appeared in a prospective setting. In total, 21 (67.7%) of these were not present in the current summaries of product characteristics.Conclusion The study demonstrated the feasibility of performing epidemiological surveillance using sequential, cumulative analyses. Larger populations are needed to evaluate rare events and infrequently used antidepressants.
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| 2. |
- Almimi, Ashraf A., et al.
(författare)
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Checking the adequacy of fit of models from split-plot designs
- 2009
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Ingår i: Journal of QualityTechnology. - : Informa UK Limited. - 0022-4065. ; 41:3, s. 272-284
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Tidskriftsartikel (refereegranskat)abstract
- One of the main features that distinguish split-plot experiments from other experiments is that they involve two types of experimental errors: the whole-plot (WP) error and the subplot (SP) error. Taking this into consideration is very important when computing measures of adequacy of fit for split-plot models. In this article, we propose the computation of two R2, R 2-adjusted, prediction error sums of squares (PRESS), and R 2 -prediction statistics to measure the adequacy of fit for the WP and the SP submodels in a split-plot design. This is complemented with the graphical analysis of the two types of errors to check for any violation of the underlying assumptions and the adequacy of fit of split-plot models. Using examples, we show how computing two measures of model adequacy of fit for each split-plot design model is appropriate and useful as they reveal whether the correct WP and SP effects have been included in the model and describe the predictive performance of each group of effects.
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| 3. |
- Almimi, Ashraf A., et al.
(författare)
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Follow-up designs to resolve confounding in split-plot experiments
- 2008
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Ingår i: Journal of QualityTechnology. - : Informa UK Limited. - 0022-4065. ; 40:2, s. 154-166
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Tidskriftsartikel (refereegranskat)abstract
- Split-plot designs are effective in industry due to time and/or cost constraints, restriction on randomization of the treatment combinations of the hard-to-change factors, and different sizes of experimental units. Some of the results of fractional factorial split-plot experiments can be ambiguous and a need may arise to conduct follow-up experiments to separate effects of potential interest by breaking their alias links with others. For completely randomized fractional factorial experiments, methods have been developed to construct follow-up experiments. In this article, we extend the foldover technique to break the alias chains of split-plot experiments. Because it is impractical or not economically possible to foldover the whole-plot factors, as their levels are often hard or expensive to change, the focus of this article is on folding over only one or more subplot factors in order to de-alias certain effects. Six rules are provided to develop foldovers for minimum aberration resolution III and resolution IV fractional factorial split-plot designs.
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| 4. |
- Andersen, Emil B., et al.
(författare)
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An easy to use GUI for simulating big data using Tennessee Eastman process
- 2022
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Ingår i: Quality and Reliability Engineering International. - : John Wiley & Sons. - 0748-8017 .- 1099-1638. ; 38:1, s. 264-282
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Tidskriftsartikel (refereegranskat)abstract
- Data-driven process monitoring and control techniques and their application to industrial chemical processes are gaining popularity due to the current focus on Industry 4.0, digitalization and the Internet of Things. However, for the development of such techniques, there are significant barriers that must be overcome in obtaining sufficiently large and reliable datasets. As a result, the use of real plant and process data in developing and testing data-driven process monitoring and control tools can be difficult without investing significant efforts in acquiring, treating, and interpreting the data. Therefore, researchers need a tool that effortlessly generates large amounts of realistic and reliable process data without the requirement for additional data treatment or interpretation. In this work, we propose a data generation platform based on the Tennessee Eastman Process simulation benchmark. A graphical user interface (GUI) developed in MATLAB Simulink is presented that enables users to generate massive amounts of data for testing applicability of big data concepts in the realm of process control for continuous time-dependent processes. An R-Shiny app that interacts with the data generation tool is also presented for illustration purposes. The app can visualize the results generated by the Tennessee Eastman Process and can carry out a standard fault detection and diagnosis studies based on PCA. The data generator GUI is available free of charge for research purposes at https://github.com/dtuprodana/TEP.
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| 5. |
- Andersen, Emil B., et al.
(författare)
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Big Data Generation for Time Dependent Processes : The Tennessee Eastman Process for Generating Large Quantities of Process Data
- 2020
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Ingår i: 30<sup>th</sup> European Symposium on Computer Aided Process Engineering. - : Elsevier. ; , s. 1309-1314
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Konferensbidrag (refereegranskat)abstract
- The concept of applying data-driven process monitoring and control techniques on industrial chemical processes is well established. With concepts such as Industry 4.0, Big Data and the Internet of Things receiving attention in industrial chemical production, there is a renewed focus on data-driven process monitoring and control in chemical production applications. However, there are significant barriers that must be overcome in obtaining sufficiently large and reliable plant and process data from industrial chemical processes for the development of data-driven process monitoring and control concepts, specifically in obtaining plant and process data that are required to develop and test data driven process monitoring and control tools without investing significant efforts in acquiring, treating and interpreting the data. In this manuscript a big data generation tool is presented that is based on the Tennessee Eastman Process (TEP) simulation benchmark, which has been specifically designed to generate massive amounts of process data without spending significant effort in setting up. The tool can be configured to carry out a large number of data generation runs both using a graphical user interface (GUI) and through a.CSV file. The output from the tool is a file containing process data for all runs as well as process faults (deviations) that have been activated. This tool enables users to generate massive amounts of data for testing applicability of big data concepts in the realm of process control for continuously operating time dependent processes. The tool is available for all researchers and other parties who are interested.
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| 6. |
- Bach Andersen, Peter, et al.
(författare)
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Added Value of Individual Flexibility Profiles of Electric Vehicle Users For Ancillary Services
- 2018
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Ingår i: 2018 IEEE International Conference on Communications, Control, and Computing Technologies for Smart Grids (SmartGridComm). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- Vehicle-Grid Integration (VGI) research may serve to limit the self-induced adverse effects of electric vehicles (EVs) in terms of additional grid loading, but also as to make the EV an active asset in supporting a stable, economic power system based on renewable energy. Any use of the vehicle for grid services requires an accurate understanding of the user's driving needs. This paper proposes the introduction of a user profile, describing the energy requirements for driving in terms of an energy deadline, target and minimum. To explore the use of such a profile, the paper analyses data from a Danish pilot project where the driving patterns of ten electric Nissan e-NV200 vans are investigated in terms of leave times and energy consumption. It is shown that the data can be fitted with a log-normal distribution that can be used to establish a per user profile which provides a certain statistical probability of fulfilling the driving needs while allowing an aggregator to optimize earnings. Initially, aggregators may apply similar driving assumptions across an entire fleet. Considering that the driving needs of individual EV owners are different, statistical representations of the individual behaviour may result in more flexibility, and thereby time, for providing grid services. The paper quantifies the value of such added flexibility based on the Danish market for frequency containment reserves.
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| 7. |
- Bekki, Jennifer M., et al.
(författare)
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Simulation-based cycle-time quantile estimation in manufacturing settings employing non-FIFO dispatching policies
- 2009
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Ingår i: Journal of Simulation. - : Informa UK Limited. - 1747-7778 .- 1747-7786. ; 3:2, s. 69-83
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Tidskriftsartikel (refereegranskat)abstract
- Previous work shows that a combination of the Cornish-Fisher Expansion (CFE) with discrete-event simulation produces accurate and precise estimates of cycle-time quantiles with very little data storage, provided all workstations in the model are operating under the first-in-first-out (FIFO) dispatching rule. The accuracy of the approach degrades, however, as non-FIFO dispatching policies are employed in at least one workstation. This paper proposes the use of a power transformation for use in combination with the CFE to combat these accuracy problems. The suggested approach is detailed, and three methods for selecting the λ parameter of the power transformation are given. The results of a thorough empirical evaluation of each of the three approaches are given, and the advantages and drawbacks of each approach are discussed. Results show that the combination of the CFE with a power transformation generates cycle-time quantile estimates with high accuracy even for non-FIFO systems.
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| 8. |
- Bisgaard, Søren, et al.
(författare)
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Checking process stability with the variogram
- 2005
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Ingår i: Quality Engineering. - 0898-2112 .- 1532-4222. ; 17:2, s. 323-327
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Tidskriftsartikel (refereegranskat)abstract
- Modern quality control methods are increasingly being used to monitor complex industrial processes. A key requirement for such methods is the derivation of long records. Once such records are obtained, the variogram becomes a simple and useful exploratory tool that can be used by quality professionals to investigate whether a process is stationary or not.
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| 9. |
- Bisgaard, Søren, et al.
(författare)
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Finding assignable causes
- 2000
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Ingår i: Quality Engineering. - : Informa UK Limited. - 0898-2112 .- 1532-4222. ; 12:4, s. 633-640
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Tidskriftsartikel (refereegranskat)
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| 10. |
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