The Experts below are selected from a list of 38658 Experts worldwide ranked by ideXlab platform
Graham J W King - One of the best experts on this subject based on the ideXlab platform.
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the flat spot of the proximal ulna a useful anatomic landmark in total elbow arthroplasty
Journal of Shoulder and Elbow Surgery, 2004Co-Authors: Naven Duggal, Cynthia E Dunning, James A Johnson, Graham J W KingAbstract:Abstract The relationship between the flat subcutaneous dorsal surface (flat spot) of the ulna and the anatomic flexion axis of the elbow was investigated in 68 cadaveric ulnae. The flat spot and the guiding ridge of the greater sigmoid notch were digitized with an electromagnetic Tracking Device. The area of the flat spot, as well as its angle with the plane of the greater sigmoid notch, was calculated. The size of the flat spot was variable but was found to be nearly perpendicular to the plane of the greater sigmoid notch (mean, 89.8° ± 6.5°). This indicates that the subcutaneous dorsal surface of the proximal ulna is a useful landmark to assist the surgeon intraoperatively to orient the ulnar component axially in total elbow arthroplasty.
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accuracy of an electromagnetic Tracking Device a study of the optimal operating range and metal interference
Journal of Biomechanics, 1996Co-Authors: Andrew D Milne, James A Johnson, David G Chess, Graham J W KingAbstract:Abstract The positional and rotational accuracy of a direct-current magnetic Tracking Device commonly used in biomechanical investigations was evaluated. The effect of different metals was also studied to determine the possibility of interference induced by experimental test fixtures or orthopaedic implants within the working field. Positional and rotational data were evaluated for accuracy and resolution by comparing the Device output to known motions as derived from a calibrated grid board or materials testing machine. The effect of different metals was evaluated by placing cylindrical metal samples at set locations throughout the working field and comparing the Device readings before and after introducing each metal sample. Positional testing revealed an optimal operational range with the transmitter and receiver separation between 22.5 and 64.0 cm. Within this range the mean positional error was found to be 1.8% of the step size, and resolution was determined to be 0.25 mm. The mean rotational error over a 1–20° range was found to be 1.6% of the rotational increment, with a rotational resolution of 0.1°. Of the metal alloys tested only mild steel produced significant interference, which was maximum when the sample was placed adjacent to the receiver. At this location the mild steel induced a positional difference of 5.26 cm and an angular difference of 9.75°. The Device was found to be insensitive to commonly used orthopaedic alloys. In this study, the electromagnetic Tracking Device was found to have positional and rotational errors of less than 2%, when utilized within its optimal operating range. This accuracy combined with its insensitivity to orthopaedic alloys should make it suitable for a variety of musculoskeletal research investigations.
A Sharifi - One of the best experts on this subject based on the ideXlab platform.
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a review of principle and sun Tracking methods for maximizing solar systems output
Renewable & Sustainable Energy Reviews, 2009Co-Authors: Hossein Mousazadeh, Alireza Keyhani, A Javadi, Hossein Mobli, Karen Abrinia, A SharifiAbstract:Finding energy sources to satisfy the world's growing demand is one of society's foremost challenges for the next half-century. The challenge in converting sunlight to electricity via photovoltaic solar cells is dramatically reducing $/watt of delivered solar electricity. In this context the sun trackers are such Devices for efficiency improvement. The diurnal and seasonal movement of earth affects the radiation intensity on the solar systems. Sun-trackers move the solar systems to compensate for these motions, keeping the best orientation relative to the sun. Although using sun-tracker is not essential, its use can boost the collected energy 10-100% in different periods of time and geographical conditions. However, it is not recommended to use Tracking system for small solar panels because of high energy losses in the driving systems. It is found that the power consumption by Tracking Device is 2-3% of the increased energy. In this paper different types of sun-Tracking systems are reviewed and their cons and pros are discussed. The most efficient and popular sun-Tracking Device was found to be in the form of polar-axis and azimuth/elevation types.
Oma Adra - One of the best experts on this subject based on the ideXlab platform.
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sun Tracking system for productivity enhancement of solar still
Desalination, 2008Co-Authors: Salah Abdallah, Oma AdraAbstract:A sun Tracking system was deployed for enhancing the solar still productivity. A computerized sun Tracking Device was used for rotating the solar still with the movement of the sun. A comparison between fixed and sun tracked solar stills showed that the use of sun Tracking increased the productivity for around 22%, due to the increase of overall efficiency by 2%. It can be concluded that the sun Tracking is more effective than fixed system and it is capable of enhancing the productivity.
Bernard F Morrey - One of the best experts on this subject based on the ideXlab platform.
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kinematics of semi constrained total elbow arthroplasty
Journal of Bone and Joint Surgery-british Volume, 1992Co-Authors: Shawn W Odriscoll, S Korinek, Bernard F MorreyAbstract:We used 11 cadaver elbows and a three-dimensional electromagnetic Tracking Device to record elbow movements before and after implantation of a 'loose-hinged' elbow prosthesis (modified Coonrad). During simulated active motion there was a maximum of 2.7 degrees (+/- 1.5 degrees) varus/valgus laxity in the cadaver joints. This increased slightly after total elbow arthroplasty to 3.8 degrees (+/- 1.4 degrees). These values are lower than those recorded for the cadaver joints and for the prostheses at the limits of their varus/valgus displacements, indicating that both behave as 'semi-constrained' joints under physiological conditions. They suggest that the muscles absorb some of the forces and moments that in a constrained prosthesis would be transferred to the prosthesis-bone interface.
Chuanqi Yan - One of the best experts on this subject based on the ideXlab platform.
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investigation of the rutting performance of various modified asphalt mixtures using the hamburg wheel Tracking Device test and multiple stress creep recovery test
Construction and Building Materials, 2019Co-Authors: Weidong Huang, Husam Sadek, Feipeng Xiao, Chuanqi YanAbstract:Abstract Asphalt modification technology is diversifying and developing complexity to overcome early permanent deformation and ensure satisfactory performance for asphalt concrete pavements. The Hamburg Wheel Tracking Device (HWTD) test has been reported to be successful in assessing asphalt mixtures’ rutting performance. This study includes a comprehensive investigation of the effects of different additives at various contents upon the HWTD testing results of asphalt mixtures. According to the degree of their improvement of the rutting performance in the HWTD test, additives were classified into three categories: (1) the first grade including linear styrene–butadiene–styrene (SBS), branched SBS and Gilsonite; (2) the second grade including high-density polyethylene, and polyphosphoric acid; and (3) the third grade including crumb rubber. Additionally, it was found that higher dosages of modifiers do not necessarily result in the improvement of Hamburg performance, and an optimal content exists for most additives. After the extensive mix testing, the dynamic shear rheometer (DSR) testing results were correlated to the HWTD test results in two categories: polymer modified asphalt and non-polymer modified asphalt. It was found that the compliance value Jnr3.2 from the Multiple Stress Creep Recovery (MSCR) test did not underestimate the rutting resistance of polymer modified asphalt compared to non-polymer modified asphalt as the current rutting factor G*/sin δ did. Jnr3.2 was more reliable than G*/sin δ in characterizing the anti-rutting performance of asphalt mixtures no matter they were polymer modified or non-polymer modified. However, different criteria for Jnr3.2 should be adopted for the polymer modified asphalt and non-polymer modified asphalt respectively.
