| 1. |
- Ali, Sharafat, Associate Professor, 1976-, et al.
(författare)
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- 2024
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Ingår i: Progress in Solid State Chemistry. - : Elsevier. - 0079-6786 .- 1873-1643. ; 74
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Forskningsöversikt (refereegranskat)abstract
- The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 degrees C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (alpha). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
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| 2. |
- Heinonen, M., et al.
(författare)
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Investigation of the Equivalence of National Dew-Point Temperature Realizations in the -50 C to + 20 C Range
- 2012
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 33:8-9, s. 1422-1437
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Tidskriftsartikel (refereegranskat)abstract
- In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4 years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from -50 C to +20 C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008 C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025 C at -50 C and 0.010 C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field.
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| 3. |
- Häggström, Caroline, et al.
(författare)
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Catalytic methanol synthesis via black liquor gasification
- 2012
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 94:1
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Tidskriftsartikel (refereegranskat)abstract
- Biofuel production from gasified black liquor is an interesting route to decrease green house gas emissions. The only pressurised black liquor gasifier currently in pilot operation is located in Sweden. In this work, synthesis gas was taken online directly from this gasifier, purified from hydrocarbons and sulphur compounds and for the first time catalytically converted to methanol in a bench scale equipment. Methanol was successfully synthesised during 45 h in total and the space time yield of methanol produced at 25 bar pressure was 0.16-0.19 g methanol/(g catalyst h). The spent catalyst exposed to gas from the gasifier was slightly enriched in calcium and sodium at the inlet of the reactor and in boron and nickel at the outlet of the reactor. Calcium, sodium and boron likely stem from black liquor whereas nickel probably originates from the stainless steel in the equipment. A slight deactivation, reduced surface area and mesoporosity of the catalyst exposed to gas from the gasifier were observed but it was not possible to reveal the origin of the deactivation. In addition to water, the produced methanol contained traces of hydrocarbons up to C 4, ethanol and dimethyl ether. © 2011 Elsevier B.V. All rights reserved.
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| 4. |
- Javadi, Hossein, et al.
(författare)
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Laboratory and numerical study on innovative grouting materials applicable to borehole heat exchangers (BHE) and borehole thermal energy storage (BTES) systems
- 2022
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Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 194, s. 788-804
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a laboratory-scale prototype of a borehole field has been designed and built to assess various innovative grouting products in a fully controlled environment. Three novel grout formulations are developed and evaluated: enhanced grout, a mixture of enhanced grout and microencapsulated phase change material, and a mixture of enhanced grout and shape stabilized phase change material. The objective is to evaluate the enhancement in their thermal properties (i.e., thermal conductivity and thermal energy storage capacity) compared to those using a commercial reference grout. Besides, three-dimensional numerical modeling is performed to provide a better understanding of the heat transfer and phase transition inside and outside the grout columns and to study the capability of the developed grouts to be used in a borehole heat exchanger or as borehole thermal energy storage system. To the best of the authors' knowledge, there have been just a few numerical studies on using phase change materials inside borehole heat exchangers to assess thermal energy storage applications. The experimental and numerical results showed much higher efficiency of the grout developed with a high thermal conductivity than the reference grout in terms of heat transfer in both the grout column and the surrounding sand. Furthermore, the results indicated the noticeable influence of the microencapsulated phase change material's presence in the grout formulation in terms of heat absorption/storage during the phase transition (from solid to liquid). However, it is concluded that reengineering shape stabilized phase change material should be conducted to make it more appropriate for thermal energy storage applications.
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| 5. |
- Karlsson, M., et al.
(författare)
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Wafer-scale epitaxial graphene on SiC for sensing applications
- 2015
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - The International Society for Optics and Photonics. - 9781628418903
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Konferensbidrag (refereegranskat)abstract
- The epitaxial graphene-on-silicon carbide (SiC-G) has advantages of high quality and large area coverage owing to a natural interface between graphene and SiC substrate with dimension up to 100 mm. It enables cost effective and reliable solutions for bridging the graphene-based sensors/devices from lab to industrial applications and commercialization. In this work, the structural, optical and electrical properties of wafer-scale graphene grown on 2'™'™ 4H semi-insulating (SI) SiC utilizing sublimation process were systemically investigated with focus on evaluation of the graphene'™s uniformity across the wafer. As proof of concept, two types of glucose sensors based on SiC-G/Nafion/Glucose-oxidase (GOx) and SiC-G/Nafion/Chitosan/GOx were fabricated and their electrochemical properties were characterized by cyclic voltammetry (CV) measurements. In addition, a few similar glucose sensors based on graphene by chemical synthesis using modified Hummer'™s method were also fabricated for comparison.
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| 6. |
- Khalifa, Shaden Ali M., et al.
(författare)
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Guidance of spiral ganglion neurons over 3 mm using protein patterned surfaces in Co-culture
- 2014
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Ingår i: Tissue Engineering and Regenerative Medicine. - : Kluwer Academic Publishers. - 1738-2696 .- 2212-5469. ; 11:3, s. 187-194
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Tidskriftsartikel (refereegranskat)abstract
- Despite considerable advances in neural prosthetics there are still few clinical devices capable of effectively compensating for the loss of a physiological function. By far the most successful to date are cochlear implants, which can restore the auditory function in patients with severe sensorineural impairment. These implants have electrode arrays that directly stimulate the remaining neurons and several strategies are applied to encourage neurons to interact intimately with the electrodes. Integration of the residual neurons into the circuits can be aided by appropriate micro-patterning on the electrodes' surfaces to guide the regenerating neurons. Here we describe experiments revealing key features of the interface between auditory cell cultures and surface patterning. In the presented study linear regenerative outgrowth of spiral ganglion axons occurred over distances of several hundred micrometers in the presence of extracellular protein cues placed precisely on surfaces by micro-contact printing. The protein pattern guided the outgrowth of spiral ganglion neurons along interconnected networks of non-neuronal cells. High-precision alignment of axons with no branching or deviation was influenced by, but not dependent upon, the presence of non-glial cells. The findings show that micro-patterning provides a versatile, robust system that can not only guide the outgrowth of individual neurons but also regulate the orientation of diverse cell types in culture. © 2014 The Korean Tissue Engineering and Regenerative Medicine Society and Springer Science+Business Media Dordrecht.
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| 7. |
- Khalifa, Shaden Ali M., et al.
(författare)
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Neuronal polarity mediated by micro-scale protein patterns and schwann cells in vitro
- 2013
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Ingår i: Tissue Engineering and Regenerative Medicine. - : Kluwer Academic Publishers. - 1738-2696 .- 2212-5469. ; 10:5, s. 266-272
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Tidskriftsartikel (refereegranskat)abstract
- Implantable electrical devices have been in use over decades to restore vital functions. Among the wellknown devices are pace makers for regulating heart rate, neurostimulators for treating neurological disorders, and cochlear implants for rescuing the hearing organ. The cochlear implant is used for patients with severe neuro-sensory hearing loss. The implant consists of an electrode that provides electrical stimuli to the spiral ganglion neurons in the cochlea, thus eliciting impulses in the pathways that normally convey auditory information from the hearing organ to the brainstem. However, disorganization of the residual spiral ganglion collaterals within and around the same frequency region of the electrode can lead to non-specific signaling and thereafter inability to discriminate the sounds. A situation that can limit considerably the maximum recovery of the auditory function after cochlear implantation. Thus, strategies that promote functional mimicry in close vicinity of the electrode are considered as potential solutions. The strict bipolarity of sensory neurons is a unique micro anatomical peculiarity of the inner ear innervations and may constitute a new option to improve sound perception within localized frequency range. In this paper, we show that minimal guidance cues provided via a simple printing technique using patterns soaked with proteins are enough to modify profoundly the polarity of regenerating spiral ganglion neurons. Regenerating spiral ganglion neurons preferentially acquired uni- or bi-polar morphology with limited branching on alternating lines structured surfaces. The neuronal processes grow in a direction parallel to the lines for distances that exceeds 2 mm.
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| 8. |
- Lu, Zhonghai, et al.
(författare)
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Wearable pressure sensing for lower limb amputees
- 2022
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Ingår i: BioCAS 2022 - IEEE Biomedical Circuits and Systems Conference. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665469173 ; , s. 105-109, s. 105-109
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Konferensbidrag (refereegranskat)abstract
- Pressure sensing in prosthetic sockets is valuable as it provides quantified data to assist prosthetists in designing comfortable sockets for amputees. We present a wearable pressure sensing system for lower limb amputees. The full system consists of three essential elements from sensing scheme (wearable sensors, sensor calibration and deployment), electronic measurement system (embedded hardware and software), to time-series database and visualization. The full system has been successfully applied in clinical trials to effectively collect pressure data in real-time.
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| 9. |
- Nikoui, T. S., et al.
(författare)
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Container-Based Load Balancing and Monitoring Approach in Fog Computing System
- 2022
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Ingår i: MELECON 2022 - IEEE Mediterranean Electrotechnical Conference, Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665442800 ; , s. 1159-1164
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Konferensbidrag (refereegranskat)abstract
- The Internet of Things has become a fast-growing area and has attracted considerable attention from the research communities. To provide satisfactory performance and efficiency in smart applications, it is inevitable to apply proper and efficient load balancing mechanisms. This paper presents a container-based load balancing and monitoring approach in fog-cloud environments. The presented architecture is composed of application services, message queuing system and online monitoring tools to address fault-detection, reliability, higher efficiency and scalability that are essential requirements of smart applications. In addition, an implementation of the proposed approach by using well-known technologies is presented, and the system is evaluated. Results indicate that using this model satisfies the requirements and can be considered as a practical solution to fog computing applications.
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| 10. |
- Skagestad, R., et al.
(författare)
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CO2stCap - Cutting Cost of CO2 Capture in Process Industry
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 114, s. 6303-6315
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Konferensbidrag (refereegranskat)abstract
- This paper is a presentation of the CO2stCap project to be undertaken in the four year project period (2015 - 2019). The project focuses on partial CO2 capture in process industry and how this can be applied to reduce cost. By performing techno-economic analyses, the optimal capture rate, including optimal design, application and configuration for different industry sources can be obtained. Cost estimation methods are used as a basis to identify and verify potentials for cost reduction when applying different options for implementation of partial CO2 capture. CO2stCap. Industries studied in this project are pulp & paper, steel, cement and metallurgical production of silicon for solar cells.
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