| 131. |
- Abayazid, Fady, et al.
(författare)
-
A New Assessment of Bicycle Helmets: The Brain Injury Mitigation Effects of New Technologies in Oblique Impacts
- 2021
-
Ingår i: Annals of Biomedical Engineering. - : Springer Science and Business Media LLC. - 1573-9686 .- 0090-6964. ; 49:10, s. 2716-2733
-
Tidskriftsartikel (refereegranskat)abstract
- New helmet technologies have been developed to improve the mitigation of traumatic brain injury (TBI) in bicycle accidents. However, their effectiveness under oblique impacts, which produce more strains in the brain in comparison with vertical impacts adopted by helmet standards, is still unclear. Here we used a new method to assess the brain injury prevention effects of 27 bicycle helmets in oblique impacts, including helmets fitted with a friction-reducing layer (MIPS), a shearing pad (SPIN), a wavy cellular liner (WaveCel), an airbag helmet (Hövding) and a number of conventional helmets. We tested whether helmets fitted with the new technologies can provide better brain protection than conventional helmets. Each helmeted headform was dropped onto a 45° inclined anvil at 6.3 m/s at three locations, with each impact location producing a dominant head rotation about one anatomical axes of the head. A detailed computational model of TBI was used to determine strain distribution across the brain and in key anatomical regions, the corpus callosum and sulci. Our results show that, in comparison with conventional helmets, the majority of helmets incorporating new technologies significantly reduced peak rotational acceleration and velocity and maximal strain in corpus callosum and sulci. Only one helmet with MIPS significantly increased strain in the corpus collosum. The helmets fitted with MIPS and WaveCel were more effective in reducing strain in impacts producing sagittal rotations and a helmet fitted with SPIN in coronal rotations. The airbag helmet was effective in reducing brain strain in all impacts, however, peak rotational velocity and brain strain heavily depended on the analysis time. These results suggest that incorporating different impact locations in future oblique impact test methods and designing helmet technologies for the mitigation of head rotation in different planes are key to reducing brain injuries in bicycle accidents.
|
|
| 132. |
- Abbas, Amr A., et al.
(författare)
-
Fast and Accurate Non-linear Model for Synchronous Machines Including Core Losses
- 2024
-
Ingår i: IEEE Transactions on Energy Conversion. - 1558-0059 .- 0885-8969. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a fast and accurate state-space model for synchronous machines taking into consideration the machine geometry, material non-linearities and core losses. The model is first constructed by storing the solutions of multiple static finite element (FE) simulations into lookup-tables (LUTs) to express the stator flux linkages as functions of the state variables, i.e., the winding currents and the rotor position. Different approaches are discussed to include the core loss into the model. A novel approach is presented for constructing a pre-computed LUT for the core loss as a function of the state variables and their time derivatives so that the loss can be directly interpolated when time-stepping the state-space model. The Simulink implementation of the proposed core-loss model shows a good match with time-stepping FE results with a 120-fold speedup in computation. In addition, comparison against calorimetric loss measurements for a 150-kVA machine operating under both sinusoidal and pulse-width modulated voltage supplies is presented to validate the model accuracy.
|
|
| 133. |
|
|
| 134. |
- Abbas, Aamer, 1973, et al.
(författare)
-
Characterization and mapping of carotenoids in the algae Dunaliella and Phaeodactylum using Raman and target orthogonal partial least squares
- 2011
-
Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 107:1, s. 174-177
-
Tidskriftsartikel (refereegranskat)abstract
- A method was developed for the characterisation of carotenoid pigments in algal species using Raman spectroscopy in combination with multivariate hyperspectral analysis. Target orthogonal partial least squares (T-OPLS) operates by designating one known reference spectrum as the target. The target spectrum is put as the single y column in an OPLS regression model where the X matrix consists of the unfolded image spectra as variables in its columns. The spectral shape of the OPLS first orthogonal target score enabled us to verify the peak positions of the standard, and detect new peaks, not present in the reference standard. It was shown that the mixture of carotenoids present in the algae did not fully match the reference spectrum, however, the method provided enough information to make an analysis possible also in this case. The image results were constructed from the OPLS loading vectors that were showing a correlation map for the reference spectrum from the predictive loadings and maps of the occurrence of deviations from the orthogonal loadings.
|
|
| 135. |
- Abbas, Aamer, 1973, et al.
(författare)
-
Chemical images of marine bio-active compounds by surface enhanced Raman spectroscopy and transposed orthogonal partial least squares (T-OPLS)
- 2012
-
Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 737, s. 37-44
-
Tidskriftsartikel (refereegranskat)abstract
- Surface enhanced Raman spectroscopy combined with transposed Orthogonal Partial Least Squares (T-OPLS) was shown to produce chemical images of the natural antibacterial surface-active compound 1,1,3,3-tetrabromo-2-heptanone (TBH) on Bonnemaisonia hamifera. The use of gold colloids function-alised with the internal standard 4-mercapto-benzonitrile (MBN) made it possible to create images of the relative concentration of TBH over the surfaces. A gradient of TBH could be mapped over and in the close vicinity of the B. hamifera algal vesicles at the attomol/pixel level. T-OPLS produced a measure of the spectral correlation for each pixel of the hyperspectral images whilst not including spectral variation that was linearly independent of the target spectrum. In this paper we show the possibility to retrieve specific spectral information with a low magnitude in a complex matrix.
|
|
| 136. |
|
|
| 137. |
- Abbas, Abdul-Karim, 1959, et al.
(författare)
-
Bicarbonate-sensitive cysteine induced elevation of extracellular aspartate and glutamate in rat hippocampus in vitro
- 1997
-
Ingår i: Neurochemistry International. - 0197-0186. ; 30:3, s. 253-259
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of different concentrations of cysteine (0.125, 0.25, 0.5 and 1 mM) on the net efflux of endogenous amino acids was studied by the incubation of rat hippocampal slices. Addition of cysteine (1 mM) in bicarbonate containing low K+ medium (5 min) selectively increased the basal net efflux of glutamate and aspartate by 370% and 396%, respectively. High K+ media (50 mM) containing cysteine (1 mM) evoked the net efflux of glutamate and aspartate by 1 454% and 1 019%, respectively. The corresponding effects in control slices without cysteine were 669% and 404%, respectively. No changes were observed on the concentrations of GABA, glutamine and taurine. The cysteine oxidation products, cysteine sulfinate (0.5 μM) and cystine (0.25 mM) were without effects. The effect of cysteine (0.5 mM) was dramatically reduced in media with no added bicarbonate/CO2. Thus, cysteine in a bicarbonate-sensitive manner selectively increases the extracellular concentration of excitotoxic amino acids in adult rat brain in vitro, possibly by interfering with the carrier-mediated glutamate uptake/ release
|
|
| 138. |
- Abbas, Nada, et al.
(författare)
-
Information Needs of Gravel Road Stakeholders
- 2022
-
Ingår i: Infrastructures. - : MDPI. - 2412-3811. ; 7:12
-
Tidskriftsartikel (refereegranskat)abstract
- Within any ecosystem, information sharing is essential. In this paper, the Swedish gravel road ecosystem is studied, where information plays a crucial role for the effective management of operations and maintenance. However, efficient information sharing is not enabled due to the lack of appropriate information systems. For addressing this issue, this paper intends to elicit information needs of gravel road stakeholders to support the design of a cloud-based information system. The main purpose is to explore the information needs of stakeholders within the Swedish gravel road ecosystem. Data were collected through in-depth semi-structured interviews with 11 participants representing key stakeholders in the ecosystem. Template analysis was used for analyzing the interview results. The major findings were a set of information needs covering road identification and condition, weather conditions, accessibility and traffic, maintenance policy, and sensor data. The results form a comprehensive information model for the further development of a cloud-based gravel road management system that would contribute to increased traffic safety and comfort, lower maintenance and management costs, and better decision-making abilities.
|
|
| 139. |
|
|
| 140. |
|
|
