| 1. |
- Abend, Sven, et al.
(författare)
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Terrestrial very-long-baseline atom interferometry : Workshop summary
- 2024
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Ingår i: AVS Quantum Science. - : American Institute of Physics (AIP). - 2639-0213. ; 6:2
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Forskningsöversikt (refereegranskat)abstract
- This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more kilometer--scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions.
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| 2. |
- Wang, Mingsheng
(författare)
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Thermodynamic modelling of aqueous solutions and applications in some functional materials synthesis
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern advances in science and technology require thedevelopment of functional materials with improved performance.Such engineered materials often have a very complex compositionand specific microstructures. These factors impose a seriouschallenge for the synthesis and processing of advancedfunctional materials.With the developments in computational modelling techniquesand the available computer power, it is now possible to design,synthesise and fabricate advanced materials with fine tunedcharacteristics suitable for the required applications. Theavailable databases ofcondensed systems provide a powerfulmodelling tool for the design of materials with the desiredmicrostructure, phase, compositions and properties. Where as,the application of thermodynamic modelling of reactions insolution offers a rational approach for optimisation of thesynthesis route for advanced functional materials.Thus, the scope of this thesis covers several aspects ofmaterials chemistry. The first part deals with the criticalevaluation of thermodynamic data and modelling of condensedphase and aqueous solutions. The second part is an experimentalstudy on the synthesis and characterisation of some functionalmaterials.Several models for the correlation of the reaction constantsto ion-hydration and ion-interaction were reviewed and thespecific interaction theory(SIT) model was selected formodelling aquatic reactions. Thermodynamic evaluation ofCu(I,II)-OH--Cl--e-system has been performed. A series ofthermodynamic properties of stability constants log K°298, and enthalpy changes ΔH°298, at infinite dilution as well as the values ofΔfG°298, ΔfH°298, S°298for complex species were critically evaluated.The interaction coefficients of the SIT, Δε, for theconcentration dependence of log K and ΔH on the ionicmedia, were also obtained. A summary of the thermodynamicassessment of the Mn-O system is performed.In the second part, a brief review of the experimentaldetails of the synthesis, based on the modelling of aqueoussolution, is presented. Different functional materials havebeen prepared by the solution chemical method. This includesaluminium-based ceramic materials: Al13cluster based materials, Al2O3based intergranular TiN nanopowder composite, andMgAl2O4spinel and thermoelectric materials, CoSb3.Several techniques have been used for thecharacterisation of these materials.The synthesis of Al13cluster based sulphate or oxalate powders wasundertaken. It was found that the Al13sulphate powders formed 3 different crystalmorphologies. The pure tetrahedral-shaped crystals of Al13sulphate was obtained with cubic structure andthe unit cell parameter a= 17.9 Å. The Al13-oxalate precipitate had spherical particles withabout 200 nm in diameter and with a narrow particle sizedistribution. A study of the decomposition and phasetransformation of both precipitated salts showed that bothpowders were converted to α-Al2O3at 1000 °C. The synthesis technique ofalumina based intergranular TiN nanopowder composite have beeninvestigated. MgAl2O4spinel ceramic powder was prepared and pure spinelphase fine powder was obtained after calcination at 1000°C. The synthesis and fabrication technique ofthermoelectric materials CoSb3with the Skutterudite structure have beeninvestigated and pure Skutterudites structure and nano sizedCoSb3has been obtained.Keywords:thermodynamics, modelling, nano-structure,Keggin, Skutterudites, spinel Al13-cluster, α-Al2O3, MgAl2O4, CoSb3, thermoelectric, TiN composite, ceramic precursor,chemical synthesis, aqueous solution, coprecipitatation.
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| 3. |
- Xia, Yangyang, et al.
(författare)
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Prediction of bending strength of glass fiber reinforced methacrylate-based pipeline UV-CIPP rehabilitation materials based on machine learning
- 2023
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier. - 0886-7798 .- 1878-4364. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet cured-in-place-pipe (UV-CIPP) materials are commonly used in trenchless pipeline rehabilitation. Their bending strength is a crucial indicator to evaluate the curing quality. Studies show that this indicator is affected by multiple factors, including the curing time, UV lamp curing power, curing distance, and material thickness. Laboratory experiments have limitations in analyzing the effect of multiple factors on the bending strength of UV-CIPP materials and quantitatively predicting the optimum curing parameters. Aiming at resolving these shortcomings, resolve machine learning techniques were applied to predict the bending strength. In this regard, the surface curing reaction temperature monitoring data and three-point bending data of 30 groups of UV-CIPP material under the influence of different curing parameters were used as a dataset to predict the bending strength of UV-CIPP material. The results show that the influence degree of each factor on the bending strength of the UV-CIPP material, from high to low, is as follows: UV lamp power (−0.439), the temperature at the illuminated side (−0.392), curing time (−0.323), the temperature at the back side (−0.233), curing distance (0.143) and material thickness (−0.140). The best penalty parameter c (44.435) and width g (0.072) of the kernel function in the support vector machine (SVM) model were obtained using the genetic algorithm (GA) optimization, and the results were compared with the grey wolf optimizer (GWO) and particle swarm optimization (PSO). The performed analyses revealed that the developed GA-SVM model exhibits the best prediction results compared to other machine learning algorithms. The optimum bending strength of the UV-CIPP material used in this test is 294.77 MPa, which corresponds to the curing time, UV lamp power, curing distance, material thickness, light side temperature, and back side temperature of 7.59 min, 157.33 mW/cm2, 189.99 mm, 4.38 mm, 79.49 °C, and 76.59 °C, respectively.
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| 4. |
- Zhang, Zongyin, et al.
(författare)
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Processing of nanostructured WC-Co powder from precursor obtained by co-precipitation
- 1999
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Ingår i: Nanostructured materials. - 0965-9773 .- 1872-9150. ; 12:1-4, s. 163-166
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Tidskriftsartikel (refereegranskat)abstract
- The paper reports the processing of a homogenous cobalt tungstate salt synthesised by co-precipitation starting from ammonium paratungstate and cobalt hydroxide. Different processing parameters such as temperatures and times of reduction and carburization and the composition of the carburization gas were studied. Powders of W and Co were obtained after the reduction of the precursor at 600 'C, 650 'C and 700 'C. The specific surface area of W-Co powders increased with decreasing reduction temperature. The carburization was carried out at 700 'C for 3 hours in different CO/CO2 - mixtures. The extent of the reaction was found to depend on the CO/CO2 - ratio. A nanophase WC-Co powder agglomerated at the micrometer scale was obtained after carburization in a 90%CO/10%CO2 gas-mixture.
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