| 61. |
- Özel, Faith, et al.
(författare)
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Prenatal exposure to phthalates and gender-specific play behavior at seven years of age in the SELMA study
- 2023
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- Background: A growing body of evidence shows that prenatal exposure to phthalates affects child development. Since many phthalates have been shown to alter endocrine signaling, they may influence reproductive development, neurodevelopment, and child behavior. Indeed, a few studies reported associations between prenatal phthalate exposure and gender-specific play behavior. However, evidence for this relationship is limited, and previous findings are based on single phthalates, while human exposure entails mixtures of chemicals. Objective: We aimed to investigate the associations between prenatal exposure to single phthalates, as well as a phthalate mixture, and gender-specific play behavior. Methods: A total of 715 mother–child pairs from the Swedish Environmental Longitudinal, Mother and Child, Asthma and Allergy (SELMA) study were included. In the median week 10 of pregnancy, phthalate metabolites were measured in urine. Gender-specific play behavior was measured with Preschool Activities Inventory at the age of seven years. Linear and weighted quantile sum regressions were used; data was stratified by sex. Models were adjusted for child and maternal age, maternal education, parental attitudes toward play behavior, and urinary creatinine concentration. Results: For boys, single compound analyses revealed negative associations of prenatal exposure to di-isononyl phthalate (DINP) concentrations with masculine (β = −1.44; 95% CI = −2.72, −0.16) and composite (β = −1.43; 95% CI = −2.72, −0.13) scores. Suggestive associations were also observed with a mixture approach identifying DINP as the main contributor of the association of decreased masculine play. Among girls, higher urinary concentrations of 2,4-methyl-7-oxyooctyl-oxycarbonyl-cyclohexane carboxylic acid (MOiNCH) was associated with decreased feminine (β = −1.59; 95% CI = −2.62, −0.57) and masculine scores (β = −1.22; 95% CI = −2.14, −0.29), whereas the mixture analyses did not yield conclusive results for girls. Conclusion: Our findings suggest associations of prenatal exposure to DINP with decreased masculine play behavior in boys while the results for girls were not fully conclusive.
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| 62. |
- Özkahraman, Özer, 1992-, et al.
(författare)
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Data-Driven Damage Detection and Control Adaptation for an Autonomous Underwater Vehicle
- 2022
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Ingår i: 61st IEEE Conference on Decision and Control (CDC), 2022.
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Konferensbidrag (refereegranskat)abstract
- Underwater robotic exploration missions typically involve traveling long distances without any human contact.The robots that go on such missions risk getting damaged by the unknown environment, accruing great costs and missed opportunities.Thus it is important for the robot to be able to accommodate unknown changes to its dynamics as much as possible and attempt to finish the given mission, or at the very least move itself to a retrievable position.In this paper, we show how we can detect physical changes to the robot reliably (79\% on real robot data) and then incorporate these changes through adapting the model to the data followed by automated control redesign. We adopt a piecewise-affine (PWA) modelling of the dynamics that is well suited for low data regime learning of the dynamics and provides a structure for computationally efficient control synthesis.We demonstrate the effectiveness of the proposed method on a combination of real robot data and simulated scenarios.
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| 63. |
- Özkılıç, Yasin Onuralp, et al.
(författare)
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Optimum usage of waste marble powder to reduce use of cement toward eco-friendly concrete
- 2023
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 25, s. 4799-4819
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Tidskriftsartikel (refereegranskat)abstract
- In this study, waste marble powder (WMP) was used to replace cement of concrete in specific amounts. To accomplish this aim, WMP was replaced at 10%, 20%, 30%, and 40% of the cement weight, and a reference concrete sample without WMP (REF) was created to compare the compressive strength, splitting tensile strength, and flexural strength. The replacement of WMP at 10%, 20%, 30%, and 40% of the cement weight resulted in 5.7%, 21.7%, 38.1%, and 43.6% decreases in the compressive strength compared with REF. Furthermore, the splitting tensile strength results commonly followed the same trend as the compressive strength. However, WMP at 10%, 20%, 30%, and 40% led to 5.3%, 8.6%, 19.4%, and 26.7% decreases in the flexural strength compared with REF. In addition, three different calculations, ranging from simple to complex, were proposed to compute mechanical resistances of concrete with WMP. These proposed calculations for practical applications were validated using values from the literature and the implications obtained from the current research. While the simple calculations were based on the strength of REF and the WMP percentages, the complex calculations were dependent on the design of the concrete mixture, age of the samples, and the WMP percentages. For the complex calculations, the ANN approach was used with the help of the coefficient of determination (R2) for the K-fold cross validation method. All the proposed methods provided high accurate estimation to predict the properties of concrete with WMP. Based on the studies, utilizing 10% WMP as the replacement of cement is recommended to obtain the optimum benefits considering both mechanical and environmental aspects. Moreover, scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses were then conducted to observe the interaction of WMP in concrete. According to the SEM analyses, some pores were detected and the interfacial transition zone was observed in the reaction zone. On the other hand, based on the EDX analyses, the presence of WMP in concrete was manifested by the presence of high levels of calcium.
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| 64. |
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| 65. |
- Özlü, Neslihan, 1980-, et al.
(författare)
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Better safe than sorry: An empirical investigation of the role of purchaser experience
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The lead times of suppliers vary considerably, causing manufacturers to suffer from low service levels and also to accumulate material and product inventories. Although various inventory control and production planning models have been studied in the operations management literature, there is scant research on the behavioral aspects of purchasing decisions beyond the ordering quantity. Drawing on transaction-level purchasing data from a large European manufacturer, we investigate the purchasers' ordering behavior under variable lead times. We examine the learning of the purchasers from their experiences with the suppliers, in terms of both how many encounters they had with the suppliers and how the experiences went. We apply two-part regression models with fixed effects to estimate the effects of purchaser experience and past supplier performance. Our analysis reveals insights into the purchasers' learning process, indicating that they rely on their prior encounters with suppliers and change their ordering behavior as they gain experience. We show that the decision to add positive safety time is driven mainly by supplier performance. With experience, purchasers become more eager to use safety time as a buffering strategy, while simultaneously learning not to overreact to past supplier performance. Furthermore, purchasers give higher weights to the normalized lateness/tardiness of their most recent encounters than to earlier ones. Our results highlight the importance of understanding the behavioral aspects that impact purchasing operations, due to which employees might have objectives that are misaligned with the company goals. This finding also points to a need for further automation of ordering tasks as well as the incorporation of behavioral factors to decision support systems.
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| 66. |
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| 67. |
- Överstam, Henrik
(författare)
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Evaluation of the improvement of rolling analysis by means of modern technology
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Modern wire rod rolling is characterised by high rolling speed and requirements on well-defined mechanical properties as well as close tolerances. Traditional methods for analyses of this kind of processes, such as the slip line field theory and the upper bound analysis, have proven not to be sufficient. Different methods for rolling analysis have been evaluated. Several FE approaches were compared to classical methods such as the upper bound and the slip line theory and the results was validated by practical experiments. The finite element method has proven to be a powerful tool in order understand the metal working process, it also gives the possibility to study phenomena not yet clarified.
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| 68. |
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| 69. |
- Överstam, Henrik
(författare)
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The influence of bearing geometry on the residual stress state in cold drawn wire, analysed by the FEM
- 2006
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 171:3, s. 446-450
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Tidskriftsartikel (refereegranskat)abstract
- Finite element simulations have been performed in order to study the influence of bearing geometry on the residual stress-state in cold drawn wires. Experiments in full industrial scale have been performed in order to verify the FEM results. The residual stresses were measured with X-ray diffraction in both the axial and tangential direction. The material used was a high carbon steel for roller bearings, 100Cr6. It was found that the geometry of the bearing has a large influence of the residual stress-state. When the bearing is somewhat tapered, a gap in the beginning of the bearing is formed. This "double contact" reduces the axial and tangential residual stress to minimum or even to a compressive state. A cylindrical bearing gave no contact in the bearing at all due to elastic deformation. This resulted in a large axial and tangential residual stress. It was shown that even a small divergence from the desired bearing geometry due to the grinding of the die could affect the residual stress immensely.
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| 70. |
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Övervakning av fladdermöss i Skåne: rapport för 2000
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fladdermössen har inventerats från bil med hjälp av ultraljudsmottagare. Jämfört med 1997 års inventering förreligger inga i täthetsindexet för nordisk fladdermus. Den största tätheten fanns i begyggt område och den lagsta i barrskogsdominerade område, i likhet det tidigare undersökningar.
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