The Experts below are selected from a list of 67125 Experts worldwide ranked by ideXlab platform
Paulo Bartolo - One of the best experts on this subject based on the ideXlab platform.
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Optimization of a Patient-Specific External Fixation Device for Lower Limb Injuries
'MDPI AG', 2021Co-Authors: Mohammed S. Alqahtani, Abdulsalam Abdulaziz Al-tamimi, Mohamed H. Hassan, Fengyuan Liu, Paulo BartoloAbstract:The use of external fixation devices is considered a valuable approach for the treatment of bone fractures, providing proper alignment to fractured fragments and maintaining fracture stability during the healing process. The need for external fixation devices has increased due to an aging population and increased trauma incidents. The design and fabrication of external fixations are major challenges since the shape and size of the defect vary, as well as the geometry of the human limb. This requires fully personalized external fixators to improve its fit and functionality. This paper presents a methodology to design personalized lightweight external fixator devices for additive manufacturing. This methodology comprises data Acquisition, Computer tomography (CT) imaging analysis and processing, Computer Aided Design (CAD) modelling and two methods (imposed predefined patterns and topology optimization) to reduce the weight of the device. Finite element analysis with full factorial design of experiments were used to determine the optimal combination of designs (topology optimization and predefined patterns), materials (polylactic acid, acrylonitrile butadiene styrene, and polyamide) and thickness (3, 4, 5 and 6 mm) to maximize the strength and stiffness of the fixator, while minimizing its weight. The optimal parameters were found to correspond to an external fixator device optimized by topology optimization, made in polylactic acid with 4 mm thickness
Bartolo Paulo - One of the best experts on this subject based on the ideXlab platform.
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Optimization of a Patient-Specific External Fixation Device for Lower Limb Injuries
'MDPI AG', 2021Co-Authors: Alqahtani, Mohammed S., Al-tamimi, Abdulsalam Abdulaziz, Hassan, Mohamed H., Liu Fengyuan, Bartolo PauloAbstract:From MDPI via Jisc Publications RouterHistory: accepted 2021-08-02, pub-electronic 2021-08-10Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; Grant(s): EP/R01513/1Funder: King Saud University; Grant(s): RSP-2021/299The use of external fixation devices is considered a valuable approach for the treatment of bone fractures, providing proper alignment to fractured fragments and maintaining fracture stability during the healing process. The need for external fixation devices has increased due to an aging population and increased trauma incidents. The design and fabrication of external fixations are major challenges since the shape and size of the defect vary, as well as the geometry of the human limb. This requires fully personalized external fixators to improve its fit and functionality. This paper presents a methodology to design personalized lightweight external fixator devices for additive manufacturing. This methodology comprises data Acquisition, Computer tomography (CT) imaging analysis and processing, Computer Aided Design (CAD) modelling and two methods (imposed predefined patterns and topology optimization) to reduce the weight of the device. Finite element analysis with full factorial design of experiments were used to determine the optimal combination of designs (topology optimization and predefined patterns), materials (polylactic acid, acrylonitrile butadiene styrene, and polyamide) and thickness (3, 4, 5 and 6 mm) to maximize the strength and stiffness of the fixator, while minimizing its weight. The optimal parameters were found to correspond to an external fixator device optimized by topology optimization, made in polylactic acid with 4 mm thickness
G.a. Johansen - One of the best experts on this subject based on the ideXlab platform.
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a data Acquisition and control system for high speed gamma ray tomography
Measurement Science and Technology, 2008Co-Authors: Bjørn Tore Hjertaker, O A Almas, Rachid Maad, E. Schuster, G.a. JohansenAbstract:A data Acquisition and control system (DACS) for high-speed gamma-ray tomography based on the USB (Universal Serial Bus) and Ethernet communication protocols has been designed and implemented. The high-speed gamma-ray tomograph comprises five 500 mCi 241Am gamma-ray sources, each at a principal energy of 59.5 keV, which corresponds to five detector modules, each consisting of 17 CdZnTe detectors. The DACS design is based on Microchip's PIC18F4550 and PIC18F4620 microcontrollers, which facilitates an USB 2.0 interface protocol and an Ethernet (IEEE 802.3) interface protocol, respectively. By implementing the USB- and Ethernet-based DACS, a sufficiently high data Acquisition rate is obtained and no dedicated hardware installation is required for the data Acquisition Computer, assuming that it is already equipped with a standard USB and/or Ethernet port. The API (Application Programming Interface) for the DACS is founded on the National Instrument's LabVIEW® graphical development tool, which provides a simple and robust foundation for further application software developments for the tomograph. The data Acquisition interval, i.e. the integration time, of the high-speed gamma-ray tomograph is user selectable and is a function of the statistical measurement accuracy required for the specific application. The bandwidth of the DACS is 85 kBytes s−1 for the USB communication protocol and 28 kBytes s−1 for the Ethernet protocol. When using the iterative least square technique reconstruction algorithm with a 1 ms integration time, the USB-based DACS provides an online image update rate of 38 Hz, i.e. 38 frames per second, whereas 31 Hz for the Ethernet-based DACS. The off-line image update rate (storage to disk) for the USB-based DACS is 278 Hz using a 1 ms integration time. Initial characterization of the high-speed gamma-ray tomograph using the DACS on polypropylene phantoms is presented in the paper.
Frank Fischer - One of the best experts on this subject based on the ideXlab platform.
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facilitating argumentative knowledge construction with Computer supported collaboration scripts
Computer Supported Collaborative Learning, 2007Co-Authors: Karsten Stegmann, Armin Weinberger, Frank FischerAbstract:Online discussions provide opportunities for learners to engage in argumentative debate, but learners rarely formulate well-grounded arguments or benefit individually from participating in online discussions. Learners often do not explicitly warrant their arguments and fail to construct counterarguments (incomplete formal argumentation structure), which is hypothesized to impede individual knowledge Acquisition. Computer-supported scripts have been found to support learners during online discussions. Such scripts can support specific discourse activities, such as the construction of single arguments, by supporting learners in explicitly warranting their claims or in constructing specific argumentation sequences, e.g., argument-counterargument sequences, during online discussions. Partici- pation in argumentative discourse is seen to promote both knowledge on argumentation and domain-specific knowledge. However, there have been few empirical investigations regarding the extent to which Computer-supported collaboration scripts can foster the formal quality of argumentation and thereby facilitate the individual Acquisition of knowledge. One hundred and twenty (120) students of Educational Science participated in the study with a 2×2-factorial design (with vs. without script for the construction of single arguments and with vs. without script for the construction of argumentation sequences) and were randomly divided into groups of three. Results indicated that the collaboration scripts could improve the formal quality of single arguments and the formal quality of argumentation sequences in online discussions. Scripts also facilitated the Acquisition of knowledge on argumentation, without affecting the Acquisition of domain- specific knowledge.
Mohammed S. Alqahtani - One of the best experts on this subject based on the ideXlab platform.
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Optimization of a Patient-Specific External Fixation Device for Lower Limb Injuries
'MDPI AG', 2021Co-Authors: Mohammed S. Alqahtani, Abdulsalam Abdulaziz Al-tamimi, Mohamed H. Hassan, Fengyuan Liu, Paulo BartoloAbstract:The use of external fixation devices is considered a valuable approach for the treatment of bone fractures, providing proper alignment to fractured fragments and maintaining fracture stability during the healing process. The need for external fixation devices has increased due to an aging population and increased trauma incidents. The design and fabrication of external fixations are major challenges since the shape and size of the defect vary, as well as the geometry of the human limb. This requires fully personalized external fixators to improve its fit and functionality. This paper presents a methodology to design personalized lightweight external fixator devices for additive manufacturing. This methodology comprises data Acquisition, Computer tomography (CT) imaging analysis and processing, Computer Aided Design (CAD) modelling and two methods (imposed predefined patterns and topology optimization) to reduce the weight of the device. Finite element analysis with full factorial design of experiments were used to determine the optimal combination of designs (topology optimization and predefined patterns), materials (polylactic acid, acrylonitrile butadiene styrene, and polyamide) and thickness (3, 4, 5 and 6 mm) to maximize the strength and stiffness of the fixator, while minimizing its weight. The optimal parameters were found to correspond to an external fixator device optimized by topology optimization, made in polylactic acid with 4 mm thickness
