| 1. |
- Ahmad, Aftab, et al.
(author)
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A model-based and simulation driven design approach for haptic devices
- 2013
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In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference--2013. - : ASME Press. - 9780791855867 ; , s. V02BT02A014-
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Conference paper (peer-reviewed)abstract
- The output from a design process of high precision and reliable haptic devices for surgical training like bones and teeth is a complex design. The complexity is largely due to the multi-criteria and conflicting character of the functional requirements. These requirements include high stiffness, large workspace, high manipulability, small inertia, low friction, and high transparency. The requirements are a basis for generating design concepts. The concept evaluation relies to a large extent on a systematic usage of kinematic, dynamic, stiffness, and friction models. The design process can benefit from a model-based and simulation driven approach, where one starts from an abstract top-level model that is extended via stepwise refinements and design space exploration into a complete realization of the system. Such an approach is presented and evaluated through a test case where a haptic device, based on a Stewart platform, has been designed and realized. It can be concluded, based on simulation and experimental results that the performance of this optimally designed haptic device satisfies the stated user requirements. This indicates that the methodology can support the development of an optimal haptic device. However, more test cases are needed to further verify the presented methodology.
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| 2. |
- Ahmad, A, et al.
(author)
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Demystifying speckle field interference microscopy
- 2022
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In: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1, s. 10869-
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Journal article (peer-reviewed)abstract
- Dynamic speckle illumination (DSI) has recently attracted strong attention in the field of biomedical imaging as it pushes the limits of interference microscopy (IM) in terms of phase sensitivity, and spatial and temporal resolution compared to conventional light source illumination. To date, despite conspicuous advantages, it has not been extensively implemented in the field of phase imaging due to inadequate understanding of interference fringe formation, which is challenging to obtain in dynamic speckle illumination interference microscopy (DSI-IM). The present article provides the basic understanding of DSI through both simulation and experiments that is essential to build interference microscopy systems such as quantitative phase microscopy, digital holographic microscopy and optical coherence tomography. Using the developed understanding of DSI, we demonstrated its capabilities which enables the use of non-identical objective lenses in both arms of the interferometer and opens the flexibility to use user-defined microscope objective lens for scalable field of view and resolution phase imaging. It is contrary to the present understanding which forces us to use identical objective lenses in conventional IM system and limits the applicability of the system for fixed objective lens. In addition, it is also demonstrated that the interference fringes are not washed out over a large range of optical path difference (OPD) between the object and the reference arm providing competitive edge over low temporal coherence light source based IM system. The theory and explanation developed here would enable wider penetration of DSI-IM for applications in biology and material sciences.
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| 3. |
- Ahmad, Ashfaq, et al.
(author)
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Design, Fabrication, and Measurements of Extended L-Shaped Multiband Antenna for Wireless Applications
- 2018
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In: Applied Computational Electromagnetics Society Journal. - : Applied Computational Electromagnetics Society (ACES). - 1054-4887. ; 33:4, s. 388-393
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Journal article (peer-reviewed)abstract
- This article expounds a multi-band compact shaped antenna, which is based on CPW ground plane. FR-4 with a thickness of 1.6 mm is used as a substrate for the proposed antenna. The proposed antenna is capable of operating at 1.56 GHz for (Global Positioning System), 2.45 GHz (Wireless Local Area Network) and 4.49 GHz (Aeronautical Mobile Telemetry (AMT) fixed services). The efficiency at 1.56, 2.45, and 4.49 GHz is 79.7, 76.9 and 76.7%, respectively. The VSWR of the presented antenna is less than 1.5 at all the desired resonance modes, which confirms its good impedance matching. The performance of the proposed antenna is evaluated in terms of VSWR, return loss, radiation pattern and efficiency. CST (R) MWS (R) software is used for simulations. In order to validate the simulation results, a prototype of the designed antenna is fabricated and a good agreement is found between the simulated and measured results.
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| 4. |
- Ahmad, Amais, et al.
(author)
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IMI – Oral biopharmaceutics tools project – Evaluation of bottom-up PBPK prediction success part 4 : Prediction accuracy and software comparisons with improved data and modelling strategies
- 2020
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In: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 156, s. 50-63
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Journal article (peer-reviewed)abstract
- Oral drug absorption is a complex process depending on many factors, including the physicochemical properties of the drug, formulation characteristics and their interplay with gastrointestinal physiology and biology. Physiological-based pharmacokinetic (PBPK) models integrate all available information on gastro-intestinal system with drug and formulation data to predict oral drug absorption. The latter together with in vitro-in vivo extrapolation and other preclinical data on drug disposition can be used to predict plasma concentration-time profiles in silico. Despite recent successes of PBPK in many areas of drug development, an improvement in their utility for evaluating oral absorption is much needed. Current status of predictive performance, within the confinement of commonly available in vitro data on drugs and formulations alongside systems information, were tested using 3 PBPK software packages (GI-Sim (ver.4.1), Simcyp® Simulator (ver.15.0.86.0), and GastroPlusTM (ver.9.0.00xx)). This was part of the Innovative Medicines Initiative (IMI) Oral Biopharmaceutics Tools (OrBiTo) project.Fifty eight active pharmaceutical ingredients (APIs) were qualified from the OrBiTo database to be part of the investigation based on a priori set criteria on availability of minimum necessary information to allow modelling exercise. The set entailed over 200 human clinical studies with over 700 study arms. These were simulated using input parameters which had been harmonised by a panel of experts across different software packages prior to conduct of any simulation. Overall prediction performance and software packages comparison were evaluated based on performance indicators (Fold error (FE), Average fold error (AFE) and absolute average fold error (AAFE)) of pharmacokinetic (PK) parameters.On average, PK parameters (Area Under the Concentration-time curve (AUC0-tlast), Maximal concentration (Cmax), half-life (t1/2)) were predicted with AFE values between 1.11 and 1.97. Variability in FEs of these PK parameters was relatively high with AAFE values ranging from 2.08 to 2.74. Around half of the simulations were within the 2-fold error for AUC0-tlast and around 90% of the simulations were within 10-fold error for AUC0-tlast. Oral bioavailability (Foral) predictions, which were limited to 19 APIs having intravenous (i.v.) human data, showed AFE and AAFE of values 1.37 and 1.75 respectively. Across different APIs, AFE of AUC0-tlast predictions were between 0.22 and 22.76 with 70% of the APIs showing an AFE > 1. When compared across different formulations and routes of administration, AUC0-tlast for oral controlled release and i.v. administration were better predicted than that for oral immediate release formulations. Average predictive performance did not clearly differ between software packages but some APIs showed a high level of variability in predictive performance across different software packages. This variability could be related to several factors such as compound specific properties, the quality and availability of information, and errors in scaling from in vitro and preclinical in vivo data to human in vivo behaviour which will be explored further. Results were compared with previous similar exercise when the input data selection was carried by the modeller rather than a panel of experts on each in vitro test. Overall, average predictive performance was increased as reflected in smaller AAFE value of 2.8 as compared to AAFE value of 3.8 in case of previous exercise.
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| 5. |
- Ahmad, Awais, 1981-, et al.
(author)
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On the Importance of Tailor-made Speech Relearning Software for Stroke Rehabilitation
- 2020
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In: Proceedings of the 6th International Conference on Information and Communication Technologies for Ageing Well and e-Health - Volume 1: ICT4AWE. - : SciTePress. - 9789897584206 ; , s. 176-179
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Conference paper (peer-reviewed)abstract
- Post stroke rehabilitation is a global issue with increasing challenges today when the percentage of older adults is increasing. There is a need for new solutions to better assist stroke survivors' normally long way back to a good and independent life. The various post stroke impairments can be divided into the categories of cognitive, motoric and speech impairment, and the three also have their interrelations. This position paper has a focus on rehabilitation of stroke survivors' speech impairments, and the use of technology-enhanced systems to assist the speech relearning. The current reuse of language learning software for primary school students is doubtful, and should better be replaced by tailor-made and adaptable tools that fit the target group. Finally, the recommendation is a long-term strategy where some initial costs should fund the design, development and evaluation of new digital tools for speech relearning. This should be conducted in a collaboration between researchers, speech therapists, stroke patients. The approach should be iterative and user-centred, with both speech therapists and stroke patients as the end-users.
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| 6. |
- Bälter, Olle, 1962-, et al.
(author)
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Walking with Seminars
- 2019
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In: KTH SoTL 2019. - Stockholm : KTH Royal Institute of Technology.
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Conference paper (peer-reviewed)abstract
- Background and purposeLow levels of physical activity and sedentary behaviour are a growing health problem globally and physical inactivity is associated with increased risk of numerous ailments, cardiovascular disease and mortality. To counteract this, the Walking seminar was invented at KTH in 2015. It is a small step towards a less sedentary lifestyle for students and teachers. Several teachers have already adopted walking seminars, but since it can be perceived as unorthodox, at least before you have tried it yourself, we offer this workshop to give hand-on experience on how to conduct a walking seminar.Work done/work in progressWe started by transforming an on-campus course into a blended course to make sure all participants had accessed the information that would be discussed during the seminar. These walking seminars were evaluated among 131 students and nine teachers leading the walking seminars (Bälter et al. 2018). The responses to the student survey and teacher interviews indicate that discussions, sense of well-being and the general quality of the seminar improved, regardless of how physically active participants were the rest of the time.Results/observations/lessons learnedStudents might be sceptical towards a walking seminar, before they have tried it. However, if introduced a day with pleasant conditions, very few are willing to go back to sitting indoors. There is some time lost for the organisation (putting on clothes, dropping of bags, opening doors), but since the discussions outdoors are way more intense than the indoor discussions, this more than makes up for the lost time. The methodology for walking seminars has evolved since its beginning and at this workshop you will get a feel for state-of-the-art when it comes to promoting and arranging a walking seminar.
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| 7. |
- Bälter, Olle, et al.
(author)
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What causes problems with email?
- 1995
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In: Proceedings of Information Technology Interfaces. ; , s. 179-186
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Conference paper (peer-reviewed)
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| 8. |
- Bälter, Olle, et al.
(author)
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Wizard-of-Oz Test of ARTUR - a Computer-Based Speech Training System with Articulation Correction
- 2005
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In: proceedings of ASSETS 2005. - 1595931597 ; , s. 36-43
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Conference paper (peer-reviewed)abstract
- This study has been performed in order to test the human-machine interface of a computer-based speech training aid named ARTUR with the main feature that it can give suggestions on how to improve articulation. Two user groups were involved: three children aged 9-14 with extensive experience of speech training, and three children aged 6. All children had general language disorders. The study indicates that the present interface is usable without prior training or instructions, even for the younger children, although it needs some improvement to fit illiterate children. The granularity of the mesh that classifies mispronunciations was satisfactory, but can be developed further.
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| 9. |
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| 10. |
- Cains, Mariana, et al.
(author)
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Environmental Management Cycles for Chemicals and Climate Change, EMC4: A new conceptual framework contextualizing climate and chemical risk assessment and management
- 2024
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In: Integrated environmental assessment and management. - 1551-3777 .- 1551-3793. ; 20:2, s. 433-453
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Journal article (peer-reviewed)abstract
- The Environmental Management Cycle for Chemicals and Climate Change (EMC4)is a suggestedconceptualframework for integrating climate change aspects into chemical risk management. The interaction of climate change and chemical risk brings together complex systems that are imperfectly understood by science. Making management decisions in this context is therefore difficult and often exacerbated by a lack of data. The consequences of poor decision making can be significant for both environmental and human health. This paper reflects on the ways in which existing chemical management systems consider climatechange and proposes theEMC4conceptual framework that isa tool for decision makersoperating at different spatial scales. Also presented are keyquestions raised by the tool to help the decision maker identify chemical risks from climate change, management options and, importantly, the different types of actors that are instrumental in managing that risk.Case studies showing decision making at different spatial scalesare also presentedhighlighting the conceptual framework’s applicability to multiple scales.The United Nations Environment Programme’s development of an intergovernmental Science Policy Panelon Chemicals and Wastehas presented an opportunity to promote and generate research highlighting the impacts of chemicals and climate changeinterlinkages.
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