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Sökning: LAR1:cth > Högskolan i Borås

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  • Abtahi, Farhad, 1981-, et al. (författare)
  • Development and preliminary evaluation of an Android based heart rate variability biofeedback system
  • 2014
  • Konferensbidrag (refereegranskat)abstract
    • The reduced Heart Rate Variability (HRV) is believed to be associated with several diseases such as congestive heart failure, diabetes and chronic kidney diseases (CKD). In these cases, HRV biofeedback may be a potential intervention method to increase HRV which in turn is beneficial to these patients. In this work, a real-time Android biofeedback application based on a Bluetooth enabled ECG and thoracic electrical bioimpedance (respiration) measurement device has been developed. The system performance and usability have been evaluated in a brief study with eight healthy volunteers. The result demonstrates real-time performance of system and positive effects of biofeedback training session by increased HRV and reduced heart rate. Further development of the application and training protocol is ongoing to investigate duration of training session to find an optimum length and interval of biofeedback sessions to use in potential interventions.
  • Abtahi, Zhohreh, et al. (författare)
  • Ethanol production by Mucor indicus at high glucose and ethanol concentrations
  • 2010
  • Ingår i: Minerva Biotecnologica. - 1120-4826. ; 22:3-4, s. 83-89
  • Tidskriftsartikel (refereegranskat)abstract
    • Mucor indicus was cultivated under aerobic and anaerobic conditions to study its tolerance against high concentration of glucose up to 350 g/L and ethanol up to 120 g/L present in the medium. The fungus could grow well even in 350 g/L glucose and produce ethanol, but it was able to assimilate the entire glucose when its concentration was less than 200 g/L. On the other hand, M. indicus produced ethanol as the main product with yield and concentration up to 0.45 g/g and 73 g/L, respectively, while glycerol, its only major byproduct, was produced up to 24 g/L. However, the fungus was not so tolerant against exogenously added ethanol, and it could not grow with more than 40 g/L added ethanol to the culture. Under aerobic conditions, M. indicus displayed different morphology, switching from long filamentous to yeast-like growth forms by increasing initial glucose concentration. This implies that yeast-like growth can be induced by growing M. indicus at high glucose concentration. Under anaerobic conditions, only one yeast-like form was observed.
  • Adekunle, Kayode (författare)
  • Bio-based Composites from Soybean Oil Thermosets and Natural Fibers
  • 2011
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • In order to reduce over-dependency on fossil fuels and to create an environment that is free of non-degradable plastics, and most importantly to reduce greenhouse gas emission, bio-based products are being developed from renewable resources through intense research to substitute conventional petrochemical-based plastics with renewable alternatives and to replace synthetic fibers with natural fibers. Many authors have done quite a lot of work on synthesizing polymers from renewable origin. Polylactic acid (PLA) has been developed and characterized, and it was found that it has enormous potential and can serve as an alternative to conventional thermoplastics in many applications. Modification of the plant oil triglycerides has been discussed by many authors, and research is still going on in this area. The challenge is how to make these renewable polymers more competitive in the market, and if possible to make them 100% bio-based. There is also a major disadvantage to using a bio-based polymer from plant oils because of the high viscosity, which makes impregnation of fibers difficult. Although natural fibers are hydrophilic in nature, the problem of compatibility with the hydrophobic matrix must be solved; however, the viscosity of the bio-based resin from plant oils will complicate the situation even more. This is why many authors have reported blending of the renewable thermoset resin with styrene. In the process of solving one problem, i.e reducing the viscosity of the renewable thermoset resin by blending with reactive diluents such as styrene, another problem which we intended to solve at the initial stage is invariably being created by using a volatile organic solvent like styrene. The solution to this cycle of problems is to synthesize a thermoset resin from plant oils which will have lower viscosity, and at the same time have higher levels of functionality. This will increase the crosslinking density, and they can be cured at room temperature or relatively low temperature. In view of the above considerations, the work included in this thesis has provided a reasonable solution to the compounded problems highlighted above. Three types of bio-based thermoset resins were synthesized and characterized using NMR, DSC, TGA, and FT-IR, and their processability was studied. The three resins were subsequently reinforced with natural fibers (woven and non-woven), glass fibers, and Lyocell fiber and the resulting natural fiber composites were characterized by mechanical, dynamic mechanical, impact, and SEM analyses. These composites can be used extensively in the automotive industry, particularly for the interior components, and also in the construction and furniture industries. Methacrylated soybean oil (MSO), methacrylic anhydride-modified soybean oil (MMSO), and acetic anhydride-modified soybean oil (AMSO) were found to be suitable for manufacture of composites because of their lower viscosity. The MMSO and MSO resins were found to be promising materials because composites manufactured by using them as a matrix showed very good mechanical properties. The MMSO resin can completely wet a fiber without the addition of styrene. It has the highest number of methacrylates per triglyceride and high crosslink density.
  • Adekunle, K., et al. (författare)
  • Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil, for use in technical applications
  • 2012
  • Ingår i: Journal of Applied Polymer Science. - 0021-8995. ; 124:6, s. 4530-4541
  • Tidskriftsartikel (refereegranskat)abstract
    • Natural fiber composites are known to have lower mechanical properties than glass or carbon fiber reinforced composites. The hybrid natural fiber composites prepared in this study have relatively good mechanical properties. Different combinations of woven and non-woven flax fibers were used. The stacking sequence of the fibers was in different orientations, such as 0°, +45°, and 90°. The composites manufactured had good mechanical properties. A tensile strength of about 119 MPa and Young's modulus of about 14 GPa was achieved, with flexural strength and modulus of about 201 MPa and 24 GPa, respectively. For the purposes of comparison, composites were made with a combination of woven fabrics and glass fibers. One ply of a glass fiber mat was sandwiched in the mid-plane and this increased the tensile strength considerably to 168 MPa. Dynamic mechanical analysis was performed in order to determine the storage and loss modulus and the glass transition temperature of the composites. Microstructural analysis was done with scanning electron microscopy.
  • Allwood, Jens, et al. (författare)
  • Work on Spoken (Multimodal) Corpora in South Africa.
  • 2010
  • Ingår i: Calzolari, N, Choukri, K. Maegaard, B, Mariani, J., Odijk, J, Piperidis, S, Rosner, M. & Tapias, D. (Eds.) Proceedings of the Seventh conference on International Language Resources and Evaluation (LREC'10) Valetta, Malta May 19-21. European Language Resources Association (ELRA). http://www.lrec-conf.org/proceedings/lrec2010/index.html (ALLWOOD 10.438).. - 2-9517408-6-7 - 2951740867
  • Konferensbidrag (refereegranskat)abstract
    • This paper describes past, ongoing and planned work on the collection and transcription of spoken language samples for all the South African official languages and as part of this the training of researchers in corpus linguistic research skills. More specifically the work has involved (and still involves) establishing an international corpus linguistic network linked to a network hub at a UNISA website and the development of research tools, a corpus research guide and workbook for multimodal communication and spoken language corpus research. As an example of the work we are doing and hope to do more of in the future, we present a small pilot study of the influence of English and Afrikaans on the 100 most frequent words in spoken Xhosa as this is evidenced in the corpus of spoken interaction we have gathered so far. Other planned work, besides work on spoken language phenomena, involves comparison of spoken and written language and work on communicative body movements (gestures) and their relation to speech.
  • Anderson, Dan, et al. (författare)
  • Approximate solution of a Thomas-Fermi model equation for bulk self-gravitating stellar objects in two dimensions
  • 2017
  • Ingår i: European journal of physics. - Institute of Physics (IOP). - 0143-0807. ; 38, s. 1-8
  • Tidskriftsartikel (refereegranskat)abstract
    • Direct variational methods are used to find simple approximate solutions of the Thomas–Fermi equations describing the properties of self-gravitating radially symmetric stellar objects both in the non-relativistic and ultra-relativistic cases. The approximate solutions are compared and shown to be in good agreement with exact and numerically obtained solutions.
  • Anderson, D., et al. (författare)
  • Galerkin approach to approximate solutions of some nonlinear oscillator equations
  • 2010
  • Ingår i: American Journal of Physics. - 0002-9505. ; 78:9, s. 920-924
  • Tidskriftsartikel (refereegranskat)abstract
    • An analysis based on the Galerkin method is given of some nonlinear oscillator equations that have been analyzed by several other methods, including harmonic balance and direct variational methods. The present analysis is shown to provide simple yet accurate approximate solutions of these nonlinear equations and illustrates the usefulness and the power of the Galerkin method. (C) 2010 American Association of Physics Teachers.
  • Anderson, D, et al. (författare)
  • Introduction to direct variational and moment methods and an application to the Child-Langmuir law
  • 2015
  • Ingår i: European journal of physics. - 0143-0807. ; 2015:36
  • Tidskriftsartikel (refereegranskat)abstract
    • A short introduction is given of direct variational methods and its relation to Galerkin and moment methods, all flexible and powerful approaches for finding approximate solutions of difficult physical equations. A pedagogical application of moment methods is given to the physically and technically important Child–Langmuir law in electron physics. The analysis is shown to provide simple, yet accurate, approximate solutions of the two-dimensional problem (a problem which does not allow an exact analytical solution) and illustrates the usefulness and the power of moment methods.
  • Anderson, D., et al. (författare)
  • The least uncomfortable journey from A to B
  • 2016
  • Ingår i: American Journal of Physics. - 0002-9505. ; 84:9, s. 690-695
  • Tidskriftsartikel (refereegranskat)abstract
    • A short introduction is given about direct variational methods and their relation to Galerkin and moment methods, all flexible and powerful approaches for finding approximate solutions to difficult physicalequations. An application of these methods is given in the form of the variational problem of minimizing the discomfort experienced during different journeys, between two fixed horizontal points while keeping the travel time constant. The analysis is shown to provide simple, yet accurate, approximate solutions of the problem and illustrates the usefulness and the power of direct variational and moment methods. It also demonstrates the problem of a priori assessing the accuracy of the approximate solutions and illustrates that the variational solution does not necessarily provide a more accurate solution than that obtained by moment methods.
  • Anderson, D., et al. (författare)
  • The optimal journey from A to B
  • 2008
  • Ingår i: American Journal of Physics. - American Association of Physics Teachers. - 0002-9505. ; 76:9, s. 863-866
  • Tidskriftsartikel (refereegranskat)abstract
    • How fast can you comfortably travel between two points A and B? This question is formulated as a minimization problem of a functional where the discomfort is quantified in terms of the integral of the square of the acceleration between A and B. The problem is solved in terms of the corresponding Euler-Lagrange equation and approximately using a direct variational approach based on trial functions and Ritz optimization. The main purpose of the analysis is to introduce undergraduate students to variational calculus in an interesting and pedagogical way.
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