| 1. |
- Gholami, Omid, 1979-, et al.
(författare)
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Heuristic Algorithms to Maximize Revenue and the Number of Jobs Processed on Parallel Machines
- 2019
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Ingår i: Automation and remote control. - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0005-1179 .- 1608-3032. ; 80:2, s. 297-316
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Tidskriftsartikel (refereegranskat)abstract
- A set of jobs has to be processed on parallel machines. For each job, there are given a release time and a due date and the job must be processed no later than its due date. If the job will be completed no later than the given due date, a benefit will be earned. Otherwise, this job will be rejected and the benefit will be discarded. The criterion under consideration is to maximize the weighted sum of the benefits and the number of jobs processed in time. Some properties of the objective function are found which allow to construct a optimal schedule. We develop a simulated annealing algorithm, a tabu search algorithm, and a genetic algorithm for solving this problem. The developed algorithms were tested on moderate and large instances with up to 500 jobs and 50 machines. Some recommendations are given showing how to use the obtained results and developed algorithms in production planning.
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| 2. |
- Hedström, Anna Karin, et al.
(författare)
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Association Between Insomnia And Mortality Is Only Evident Among Long Sleepers
- 2019
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Ingår i: Nature and Science of Sleep. - 1179-1608. ; 11, s. 333-342
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous studies investigating the relationship between insomnia and mortality have been inconsistent. Purpose: We aimed to assess whether nocturnal insomnia symptoms and non-restorative sleep are associated with all-cause mortality and whether they modify the associations between short and long sleep duration and all-cause mortality. Patients and methods: The present report is based on a prospective cohort study of 39,139 participants with a mean follow-up time of 19.6 years. Cox proportional hazard models with attained age as timescale were used to estimate overall mortality hazard ratios (HRs) with 95% confidence intervals (CI) for different categories of sleep duration and insomnia symptoms. Results: Both difficulty initiating sleep and daytime sleepiness were independently associated with increased mortality among those with sleep duration of 9 hrs or more (HR 1.51, 95% CI 1.11-2.07 and HR 1.37, 95% CI 1.03-1.82). Mortality increased with increasing severity of difficulties initiating sleep (p for trend 0.04) and daytime sleepiness (p for trend 0.01) among the long sleepers. None of the insomnia symptoms were associated with mortality among those who reported sleep duration of 8 hrs or less. Conclusion: Long sleep in combination with difficulties initiating sleep and daytime sleepiness, possibly due to psychiatric or physical disorders, was thus associated with increased mortality, whereas long sleep without difficulties falling asleep or daytime sleepiness was not associated with mortality. Our study emphasizes the need to take nocturnal insomnia symptoms and daytime sleepiness into consideration when assessing the influence of sleep duration on mortality. Additional research is needed to elucidate the relationship between long sleep, insomnia and related psychiatric and physical disorders.
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| 3. |
- Krasheninnikov, Pavel V., et al.
(författare)
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Parameter Estimation for the Resulting Logical Channel Formed by Minimizing Channel Switching
- 2019
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Ingår i: Automation and remote control. - : Springer. - 0005-1179 .- 1608-3032. ; 80:2, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- We propose a method for calculating the parameters of the resulting discrete channel for secondary users in cognitive radio systems formed by the algorithm for minimizing channel switchings. The availability of channel slots is defined by a simple Markov chain. We obtain mathematical expressions for determining the transition probabilities of a graph reduced to two states for any number of primary channels.
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| 4. |
- Ljung, Lennart
(författare)
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On Convexification of System Identification Criteria
- 2019
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Ingår i: Automation and remote control. - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0005-1179 .- 1608-3032. ; 80:9, s. 1591-1606
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Tidskriftsartikel (refereegranskat)abstract
- System Identification is about estimating models of dynamical systems from measured input-output data. Its traditional foundation is basic statistical techniques, such as maximum likelihood estimation and asymptotic analysis of bias and variance and the like. Maximum likelihood estimation relies on minimization of criterion functions that typically are non-convex, and may cause numerical search problems and estimates trapped in local minima. Recent interest in identification algorithms has focused on techniques that are centered around convex formulations. This is partly the result of developments in semidefinite programming, machine learning and statistical learning theory. The development concerns issues of regular-ization for sparsity and for better tuned bias/variance trade-offs. It also involves the use of subspace methods as well as nuclear norms as proxies to rank constraints. A special approach is to look for difference-of-convex programming (DCP) formulations, in case a pure convex criterion is not found. Other techniques are based on Lagrangian relaxation and contraction theory. A quite different route to convexity is to use algebraic techniques to manipulate the model parameterizations. This article will illustrate all this recent development.
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| 5. |
- Miley-Åkerstedt, Anna, et al.
(författare)
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Criteria for self-reported quantitative sleep characteristics of individuals who sought medical help for disturbed sleep - a survey of a representative sample of the Swedish population
- 2018
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Ingår i: Nature and Science of Sleep. - 1179-1608. ; 10, s. 295-301
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Tidskriftsartikel (refereegranskat)abstract
- Background: The public often seeks rule-of-thumb criteria for good or poor sleep, with a particular emphasis on sleep duration, sleep latency, and the number of awakenings each night. However, very few criteria are available. Aim: The present study sought to identify such criteria. Methods: Whether or not a person has sought medical help for sleep problems was selected as an indicator of poor sleep. The group that was studied constituted a representative sample of the general Swedish population (N=1,128), with a response rate of 72.8%. Results: Logistic regression analysis, with an adjustment for age and gender, showed an increased OR for a weekday sleep duration of <= 6 hour, (OR >2, and for <5 hour: OR >6). For weekend sleep, the value was <= 6 hour (OR >2). For awakenings per night, the critical value was >= 2 (OR >2, and for awakenings: OR >9), and for a sleep latency the critical value was >= 30 minutes (OR >2, and for >= 45 minutes: OR >6). Adding difficulties falling asleep and early morning awakening (considered qualitative because of the reflected difficulty), led to the elimination of all the quantitative variables, except for the number of awakenings. The addition of negative effects on daytime functioning and sleep being a big problem resulted in the elimination of all the other predictors except age. Conclusion: It was concluded that weekday sleep <= 6 hour, >= 2 awakenings/night, and a sleep latency of >= 30 minutes, can function as criteria for poor sleep, but that qualitative sleep variables take over the role of quantitative ones, probably because they represent the integration of quantitative indicators of sleep.
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