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| 2. |
- Abdullah, Twana, 1977-
(författare)
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Groundwater Vulnerability Assessment to pollution in Different Soil and Rock Materials
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The augmentation of human population regularly corresponds with change in the land cover, including expansion of urban areas, which imposes increasing the available amount of domestic and drinking water. The study area, Halabja-Saidsadiq Basin, is situated in the Northeast of Iraq and is one of the major groundwater sources of the region. As the surface water sources are not enough in the studied area, it has become necessary to use groundwater at an increasing rate. Usually, a huge amount of groundwater is plentiful in the alluvial deposits or rock outcrops where the urban areas are frequently situated. Such areas face a huge risk of pollution of groundwater due to producing different sources of a contaminant from human's activity. Keeping these aspects in view, groundwater vulnerability studies have been carried out in the current studied basin. The main objective of this work is to investigate the environmental impacts on groundwater quality and recognize the groundwater vulnerability in the area so that the groundwater can be protected from probable contaminations.In the current study, DRASTIC model has been applied since it is one of the most proper useful methods available for the assessment of the groundwater vulnerability. This model has been modified in different ways to achieve the obvious vulnerability condition in the area; likewise, different further methods have been applied for comparison purposes such as: weight modified VLDA and standard COP models. In addition, the applied models were validated by comparing its findings against the estimated groundwater ages and the observed water characteristic qualities within the region in two successive seasons.According to the spatial distribution of irrigation water quality index, groundwater at the studied basin classified into three group for both dry and wet seasons, namely, Sever Restriction (SR), High Restriction (HR) and Moderate Restriction (MR). The coverage area of all three classes are (1.4%, 52.4% and46.2%) for dry season and (0.7%, 83.3% and16%) for wet seasons, respectively. While, refer to the water quality index for drinking purpose, groundwater in this basin reveals a permissible to excellent groundwater quality of the dry season and a good to excellent groundwater quality of the wet season. The high level of a good groundwater quality in the wet season compared to the dry season might be expected to the groundwater recharge during the winter and spring periods, which lead to dilution of chemical component, in contrast high irrigation and agricultural activities and groundwater discharge in the dry season leads to increase the concentration of chemical component.Field and official data were collected to review several environmental impacts and were used to map standard DRASTIC vulnerability model for the study basin. Based on this model, the study area was classified into four zones of vulnerability indexes, comprises a very low, low, moderate and high vulnerability index with a coverage area of (34%, 13%, 48% and 5%) respectively.In the first modification step, the rate and weight value of each parameter in DRASTIC model is modified. Nitrate concentration from 39 groundwater samples was used for modifying the recommended standard rating value based on the Wilcoxon rank-sum nonparametric statistical test and then sensitivity analysis was used to modifying recommended standard weighting value of each parameter. To calibrate the modified rate, the Pearson's correlation coefficient was applied to estimate the relation between DRASTIC values and nitrate concentrations in groundwater samples. For the first modified model, the correlation coefficient was 72% that was significantly higher than 43% achieved for the standard model. The modified model classified the area into five vulnerability classes, including (very low, low, moderate, high and very high) with covered area of (7%, 35%, 19%, 35% and 4%), respectively.The second modification of DRASTIC model was based on land use and land cover for the studied area. The land use and land cover (LULC) map prepared using ERDAS IMAGINE software from two different scenes of Landsat Thematic Mapper (TM). The LULC map indicates that only five classes of LULC can be identified: these are: barren land, agricultural land, vegetation land, urban area and wet land or water body. The modified DRASTIC based on LULC map classified the area into five classes with different coverage area of each class: very low (1.17%), low (36.82%), moderate (17.57%), high (43.42%) and very high (1.02%).The third modified method of the current study is the modification of DRASTIC model based on Lineament feature of the study basin. A lineament map is extracted from Enhanced Thematic Mapper plus (ETM+) satellite imagery using different techniques in remote sensing and GIS. The lineament density map demonstrates that only six classes of lineament density can be identified ranged from (0-2.4). The third modified DRASTIC model classified the area into four vulnerability categories: very low (28.75%), low (14.31%), moderate (46.91%) and high (10.03%).The fourth effort to modify standard DRASTIC model is the application of Analytical Hierarchical Process (AHP) to assess the weight value of each parameter. The modified DRASTIC vulnerability index values based on AHP method ranged between (65.82–224.1) with five vulnerability classes comprises (very low to very high).Weight modified VLDA and standard COP models were also applied to map vulnerability system in the study basin. The vulnerability outcome based on weight modified VLDA model revealed that a total of four ranges of vulnerability indexes had been distinguished ranging from low to very high with vulnerability indexes (2.133-9.16). Subsequently, based on the standard COP model, the area is also divided into four vulnerability classes ranging from very low to high with index value ranged from (0.79) to (6.2).All applied models in the study basin were compared to each other and validated to clarify the validity of the theoretical sympathetic of current hydrogeological conditions and to show the accuracy of the modeled vulnerability system. Two methods were applied for the validation of the result, in the first approach; nitrate concentration analysis has been selected; the nitrate differences between two following seasons (dry and wet) were analyzed from (39) water wells. In the second approach, groundwater vulnerability was assessed based on estimated groundwater age from range of tritium (3H) value in the groundwater samples from different groundwater aquifers in the studied area. The results of both validation methods verify the sensibility of the gradation and distribution of vulnerability levels acquired using the modified DRASTIC model based on (rate and weight modification, weight modification based on AHP process and effect of LULC on DRASTIC model) and also applying weight modified of VLDA model.
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| 3. |
- Acampora, Giovanni, et al.
(författare)
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Preface
- 2020
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Ingår i: Computational Intelligence for Semantic Knowledge Management. - : Springer Nature. ; , s. vii-x
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Acharya, Sarthak, et al.
(författare)
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An Additive Production approach for Microvias and Multilayered polymer substrate patterning of 2.5μm feature sizes
- 2020
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Ingår i: IEEE 70th Electronic Components and Technology Conference. - : IEEE. ; , s. 1304-1308
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Consumer electronics market is escalating towards the miniaturization and the use of HDI-PCBs is dominating. Thus, the production technologies are adapting the Semi-Additive process (SAP) or modified-SAP (mSAP) methods over conventional subtractive print-and-etch methods. Most of the Smartphone manufacturers are using Substrate-like PCB (SLP) with mSAP techniques to scale down the Lines and Spaces (L&S) on PCBs equivalent to ICs. However, those processes still involve subtractive patterning in the intermediate stages of fabrication. In this paper, a fully additive multi-layer patterning process using an electroless copper plating has been investigated. This patterning process is based on modifying a polymer surface by activating a seed layer of grafting polymer chains on it using optimized UV-Laser parameters. This surface modification enables a strong bonding of Copper (Cu) onto the modified surface by Cu-plating. Using a micrometer via laser ablation and subsequent sub-micrometer laser lithography a 2.5D surface pattern has been achieved with the proposed technique.So far, using the proposed additive production process the feature sizes of 2.5 μm L&S and via of diameter 10 μm have been achieved.The via ablation and pattering were done by using 266nm and 375nm laser sources respectively.The substrates used are standard FR4 material and a layer of polyurethane of thickness 35μm coated on top of it. Analysis of the process parameters and their optimization has been done by factorial design method using Design Expert 12.0 software to show their contribution and significance in the production process.
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| 5. |
- Allinson, James, et al.
(författare)
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Collating data from major European population studies - The CADSET (Chronic airway disease early stratification) clinical research collaboration
- 2020
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 56:suppl 64
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: European population cohorts continue to expand our understanding of chronic airways disease and inter-study collaboration may help address the inevitable limitations of study size, duration, era and geography. Towards this aim, CADSET has collated data from ten major general population European cohorts: Asklepios; Copenhagen City Heart Study; Copenhagen General Population Study; ECRHS; HUNT; LEAD; Lifelines, OLIN, Rotterdam Study and WSAS. We included males and females aged 20 to 95 years with baseline demographic and spirometry data.Results: Data from 262,829 individuals (44% male) from multiple European countries provided good coverage across all adult ages (Fig.1A). Recruitment occurred in every year from 1976 through 2020. 23% were current-smokers and 42% were never-smokers, a pattern varying with advancing age (Fig.1B). The prevalence of airflow limitation varied according to whether lower limit of normal (LLN) or <0.70 thresholds were applied, increasing with age if the latter was used (Fig.1C).Interpretation: These results fit with previous reports, however the size, geographical reach and span of recruitment provided by this collaboration provides a unique opportunity to explore chronic airways disease development. Together, we are now pursuing research questions previously beyond the scope of individual cohort studies.
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| 6. |
- Allwood, Carl-Alexander, et al.
(författare)
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Lärande på bondgård : Rapport om det lärande som kan ske när barn besöker ett lantbruk
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Studien beskriver och diskuterar det lärande som kan ske då elever besöker ett lantbruk. Despecifika frågeställningarna löd: (1) Vilka avsikter för barns lärande finns det med besök till en lantgård? (2) Hur kan lärandet som sker på en lantgård beskrivas? För att besvara frågeställningarna genomfördes en fallstudie på en mindre lantgård som i hög grad var anpassad för att kunna ta emot barngrupper och studiebesök. Totalt analyserades sex intervjuer, ett fokusgruppsamtal, två heldagsobservationer och två anknytande enkäter som besvarades av 18 barn innan och efter deras besök till lantbruket. Resultatet visar att de avsikter som de vuxna aktörerna uttryckte kan beskrivas som att de ville göra barnen medvetna om norrbottnisk matproduktion; utveckla en positiv känsla för hållbar konsumtion; att de menade att lantbrukskunskap var en demokratisk rättighet; samt att utveckla kunskaper som anknöt till skolans läroplan. Det lärande som skedde kunde beskrivas som att barnen utvecklade: Praktiska kunskaper i lantbrukspraktiken; sakkunskaper i lantbrukspraktiken; samt emotionella kompetenser. I diskussionen överväger vi på vilket sätt studiebesök till lantbruk kan komplettera skolans undervisning. Lantbruket erbjuder en autentisk miljö där praktisk kunskap, sakkunskap och emotionella kompetenser, vilka alla har starkt stöd i skolans läroplan, kan utvecklas. Vår studie pekar också på att ett studiebesök till ett lantbruk fungerar väl för att konkretisera och synliggöra värdegrunden och läroplanens övergripande miljöperspektiv.
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| 7. |
- Almqvist, Andreas, et al.
(författare)
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Modelling Flows in Lubrication
- 2020. - 1
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Ingår i: Modeling and Simulation of Tribological Problems in Technology. - Cham : Springer. ; , s. 229-278
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter introduces the reader to lubrication theory and describes the governing equations, models and methods that can be used to simulate various types of lubricated systems. It starts with an introduction to the tribological contact and to the different lubrication regimes. The basis for the classical lubrication theory is then given and thereafter follows a presentation of how to obtain the Reynolds equation by means of scaling and asymptotic analysis of the Navier–Stokes equations. After having obtained the Reynolds equation, a quite elaborate presentation of cavitation algorithms is given. It includes discretisation and presents the analytical solution for a pocket bearing as a benchmark model problem. Then, the concept of homogenisation of surface roughness is introduced. This starts from the simplest iso-viscous and incompressible case, expands to include compressibility with a constant bulk modulus constitutive relation and then also addresses the case of ideal gases. Thereafter, the relation between homogenised coefficients and the Patir and Cheng flow factors is described and finally it is shown how to incorporate the effect of mixed lubrication into the model.
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| 8. |
- Almqvist, Linnéa, et al.
(författare)
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Clinical outcome of adult onset asthma in a 15 year follow-up
- 2020
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 56:Suppl 64
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Adult onset asthma is poorly studied and there are few long-term clinical follow-up studies.Aim: To study clinical characteristics of adult onset asthma in a 15-year follow-up.Method: Within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, a cohort of n=309 subjects with adult onset asthma (aged 20-60 years) was recruited during 1995-99. The cohort was followed up in 2012-14 (n=205). Structured interviews and clinical examinations including spirometry were performed at both recruitment and follow-up. Skin prick tests were performed at recruitment and blood samples for cell counts and IgE at the follow-up. Asthma control was classified according to GINA 2006.Results: At follow-up n=182 (89%) still had asthma, while n=23 (11%) were in remission. Among individuals with persistent asthma, mean pre-bronchodilator FEV1 percent of predicted was 89.0 at follow-up, similar as recruitment 88.3. At recruitment 16.5% were smokers, and of these, 86.7% had quit smoking at follow-up. At follow-up, 39% had blood neutrophils ≥4.0x109/L, 23% had blood eosinophils ≥0.3x109/L, and 28% had specific IgE>0.35 IU/ml to any airborne allergen. Any respiratory symptoms were reported by 90% and 31% used medium or high dose inhaled corticosteroids (ICS), 20% low dose ICS whereas 20% had no treatment. 55% had controlled asthma, 32% partly controlled and 13% uncontrolled asthma.Conclusion: In this 15-year follow-up of adult onset asthma, the majority had persistent asthma. Smoking and high proportion using ICS may contribute to the stable lung function. Still, it should be noted that merely around every other had well controlled asthma.
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| 9. |
- Alonso, Pedro, 1986-
(författare)
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Faster and More Resource-Efficient Intent Classification
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intent classification is known to be a complex problem in Natural Language Processing (NLP) research. This problem represents one of the stepping stones to obtain machines that can understand our language. Several different models recently appeared to tackle the problem. The solution has become reachable with deep learning models. However, they have not achieved the goal yet.Nevertheless, the energy and computational resources of these modern models (especially deep learning ones) are very high. The utilization of energy and computational resources should be kept at a minimum to deploy them on resource-constrained devices efficiently.Furthermore, these resource savings will help to minimize the environmental impact of NLP.This thesis considers two main questions.First, which deep learning model is optimal for intent classification?Which model can more accurately infer a written piece of text (here inference equals to hate-speech) in a short text environment. Second, can we make intent classification models to be simpler and more resource-efficient than deep learning?.Concerning the first question, the work here shows that intent classification in written language is still a complex problem for modern models.However, deep learning has shown successful results in every area it has been applied.The work here shows the optimal model that was used in short texts.The second question shows that we can achieve results similar to the deep learning models by more straightforward solutions.To show that, when combining classical machine learning models, pre-processing techniques, and a hyperdimensional computing approach.This thesis presents a research done for a more resource-efficient machine learning approach to intent classification. It does this by first showing a high baseline using tweets filled with hate-speech and one of the best deep learning models available now (RoBERTa, as an example). Next, by showing the steps taken to arrive at the final model with hyperdimensional computing, which minimizes the required resources.This model can help make intent classification faster and more resource-efficient by trading a few performance points to achieve such resource-saving.Here, a hyperdimensional computing model is proposed. The model is inspired by hyperdimensional computing and its called ``hyperembed,'' which shows the capabilities of the hyperdimensional computing paradigm.When considering resource-efficiency, the models proposed were tested on intent classification on short texts, tweets (for hate-speech where intents are to offend or not to), and questions posed to Chatbots.In summary, the work proposed here covers two aspects. First, the deep learning models have an advantage in performance when there are sufficient data. They, however, tend to fail when the amount of available data is not sufficient. In contrast to the deep learning models, the proposed models work well even on small datasets.Second, the deep learning models require substantial resources to train and run them while the models proposed here aim at trading off the computational resources spend to obtaining and running the model against the classification performance of the model.
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| 10. |
- Alvi, Sajid Ali
(författare)
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Refractory High Entropy Alloys and Films for High Temperature Applications
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-entropy alloy (HEA) is a multi-component alloy constituting five or more principal elements in equi- or near equi-atomic percentages. The high configurational entropy in a HEA composition, in contrast to conventional alloys, leads to the stabilisation of the alloying elements in stable solid solutions of face-centred-cubic (FCC), body-centred-cubic (BCC) and/or amorphous structures. The characteristic properties of HEAs are mainly governed by lattice distortion, sluggish diffusion and entropy- and cocktail-effects. Refractory high-entropy alloys (RHEAs), consisting of refractory elements, are considered as a paradigm shift in developing materials for high temperature applications.The current PhD project investigates four different aspects of RHEAs. First, it involves developing CuMoTaWV RHEA by spark plasma sintering (SPS) and utilising the cocktail effect of HEAs for high temperature tribological application. The use of the cocktail effect, defined as selecting favourable compositions for particular applications, is utilised for RHEA compositions in order to yield adaptive tribological behaviour at changing temperatures or environments. The sintered CuMoTaWV showed formation of BCC solid solution and a composite microstructure. The high temperature tribological investigations showed an adaptive behaviour at different temperatures. At lower temperatures Cu lowered the wear rate through formation of CuO, and at higher temperatures V enhanced the tribological resistance through formation of lubricating V2O5 phases.The second aspect involves studying the effect of lattice distortion on mechanical properties of magnetron sputtered thin film after adding Cu to the refractory elements of Mo, Ta, W and V. A target of CuMoTaWV was developed through partial sintering and used to deposit thin film on different substrates. The deposited film showed formation of BCC solid solution, which was verified through DFT calculations. The lattice distortion in CuMoTaWV film showed high hardness and nano-pillar compressive strength. Furthermore, the tribological properties were enhanced at temperatures up to 400oC due to the addition of Cu.The third aspect involves studying the effect of configurational entropy on the formation and high temperature stability of refractory high-entropy thin film metallic glass and its nitrides, by increasing the number of principal elements. A partially sintered target of TiVZrNbMoHfTaW was used to deposit thin films of metallic glass and nitrides through magnetron sputtering. The metallic glass thin films and its nitrides were found to have high hardness of 7.3 GPa and 19–43 GPa, respectively. Furthermore, the metallic glass thin films showed a high nano-pillar compressive strength of up to 3 GPa, almost twice as high as conventional metallic glass films. The phase stability of metallic glass and its nitride thin films were found to be stable at temperatures up to 750oC and 950oC, respectively. The exceptionally superior mechanical properties and high temperature stability has been attributed to the presence of high configurational entropy. The last part of this PhD thesis consists of studying high-entropy-based W-rich alloys for high temperature applications. A W-based alloy of composition W0.5(TaTiVCr)0.5 was consolidated using SPS. The resulting alloy revealed a BCC solid solution structure. The microstructure of W-rich alloys consist of a combination of W-rich, high-entropy and TiC phases. The BCC solid solution structure in W-rich alloys was found to be stable with exceptionally high compressional strength up to 1,400oC. A high compressive yield strength of 1136 ± 40 MPa, 830 ± 60 MPa and 425 ± 15 MPa was found at test temperatures of 1,000oC, 1,200oC and 1,400oC, respectively. The resulting high strength has been related to the formation of high-entropy phases, which in return induces sluggish diffusion at higher temperatures. The high temperature tribology at 400oC showed an average COF and low wear rate of 0.5 and 1.37 x 10-5 mm3/Nm, respectively. The high temperature wear resistance at 400oC was enhanced due to the presence of HEA and TiC phases. The studies carried out in this thesis suggest the possibility of utilising the full potential of the cocktail effect, lattice distortion and configurational entropy in designing new high-entropy compositions for applications requiring adaptive tribological behaviour, superior mechanical properties and high temperature phase stability.
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