Autor: Chang, T.-K. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Optimal screw orientation for the fixation of cervical degenerative disc disease using nonlinear C3-T2 multi-level spinal models and neuro-genetic algorithms
Autorzy:: Chang, T.-K.
Hsu, C.-C.
Chen, K.-T.
Tematy:: stabilizacja
optymalizacja
kątownik
bioinżynieria
cervical plate
insertion angle
fixation stability
optimization; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/306375.pdf Link otwiera się w nowym oknie
Opis:: Purpose: Anterior cervical discectomy and fusion is a common surgical procedure performed to remove a degenerative or herniated disc in cervical spine. Unfortunately, clinical complications of anterior cervical plate (ACP) systems still occur, such as weak fixation stability and implant loosening. Previous researchers have attempted to ameliorate these complications by varying screw orientations, but the screw orientations are mainly determined according to the investigator’s experiences. Thus, the aim of this study was to discover the optimal screw orientations of ACP systems to achieve acceptable fixation stability using finite element simulations and engineering algorithms. Methods: Three-dimensional finite element models of C3-T2 multi-level segments with an ACP system were first developed to analyze the fixation stability using ANSYS Workbench 14.5. Then, artificial neural networks were applied to create one objective function, and the optimal screw orientations of an ACP system were discovered by genetic algorithms. Finally, the numerical models and the optimization study were validated using biomechanical tests. Results: The results showed that the optimal design of the ACP system had highest fixation stability compared with other ACP designs. The neuro-genetic algorithm has effectively reduced the time and effort required for discovering for the optimal screw orientations of an ACP system. Conclusions: The optimum screw orientation of the ACP system could be successfully discovered, and it revealed excellent fixation stability for the treatment of cervical degenerative disc disease. This study could directly provide the biomechanical rationale and surgical suggestion to orthopedic surgeons.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 2.

Tytuł:: Effect of Vacuum Hot-Press Process on The Sintered Characteristics and Mechanical Properties of A High-Density Cr-31.2 Mass% Ti Alloy
Autorzy:: Chang, S.-H.
Li, C.-L.
Huang, K.-T.
Yang, T.-H.
Tematy:: Cr-31.2 mass% Ti alloy
vacuum hot-press sintering
relative density
TRS
electrical conductivity; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/356911.pdf Link otwiera się w nowym oknie
Opis:: In this study, two different compositions of submicron-structured titanium (760 nm) and micron-structured chromium (4.66 μm) powders were mixed to fabricate Cr-31.2 mass% Ti alloys by vacuum hot-press sintering. The research imposed various hot-press sintering pressures (20, 35 and 50 MPa), while the sintering temperature maintained at 1250°C for 1h. The experimental results showed that the optimum parameters of the hot-press sintered Cr-31.2 mass% Ti alloys were 1250°C at 50 MPa for 1h. Also, the relative density reached 99.94%, the closed porosity decreased to 0.04% and the hardness and transverse rupture strength (TRS) values increased to 81.90 HRA and 448.53 MPa, respectively. Moreover, the electrical conductivity is enhanced to 1.58 × 10⁴ S·cm^-1 However, the grain growth generated during the high-temperature and high-pressure of the hot-press sintering process resulted in the grain coarsening phenomenon of the Cr-31.2 mass% Ti alloys after 1250°C hot-press sintering at 50 MPa for 1h. In addition, the Cr-31.2 mass% Ti alloys were fabricated with the submicron-structured titanium (760 nm) and chromium (588 nm) powders showed more effective compaction than the micron-structured titanium (760 nm) and chromium (4.66 μm) powders did. The closed porosity decreases to 0.02% and the hardness values increase to 83.23 HRA. However, the agglomeration phenomenon of the Cr phase and brittleness of the TiCr₂ Laves phases easily led to a slight decrease in TRS (400.54 MPa).
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 3.

Tytuł:: First search for axionlike particles in a storage ring using a polarized deuteron beam
Autorzy:: Chang, S. P.
Park, S.
Pretz, J.
Siddique, S.
Jeong, H.
Nikolaev, N. N.
Semertzidis, Y. K.
Pesce, A.
Bekman, I.
Kacharava, A.
Valdau, Y.
Kononov, A.
Laihem, K.
Grzonka, D.
Abusaif, F.
Lorentz, B.
Ciullo, G.
Magiera, Andrzej
Wüstner, P.
Mchedlishvili, D.
Grigoryev, K.
Shergelashvili, D.
Alberdi, B.
Poncza, V.
Canale, N.
Javakhishvili, O.
Hejny, V.
Rathmann, F.
Karanth, Swathi
Kamerdzhiev, V.
Ströher, H.
Beyß, M.
Böhme, C.
Hetzel, J.
Müller, F.
Breitkreutz, B.
Saleev, A.
Soltner, H.
Lomidze, N.
Andres, A.
Vitz, M.
Lehrach, A.
Dymov, S.
Prasuhn, D.
Slim, J.
von Byern, C.
Gebel, R.
Shmakova, V.
Tabidze, M.
Shurkhno, N.
Keshelashvili, I.
Aggarwal, Anjali
Lenisa, P.
Stassen, R.
Wirzba, A.
Fröhlich, N.-O.
Wagner, T.
Aksentev, A.
Barion, L.
Stephenson, E. J.
Nass, A.
Wrońska, Aleksandra
Tagliente, G.
Opis:: Based on the notion that the local dark-matter field of axions or axionlike particles (ALPs) in our Galaxy induces oscillating couplings to the spins of nucleons and nuclei (via the electric dipole moment of the latter and/or the paramagnetic axion-wind effect), we establish the feasibility of a new method to search for ALPs in storage rings. Based on previous work that allows us to maintain the in-plane polarization of a stored deuteron beam for a few hundred seconds, we perform a first proof-of-principle experiment at the Cooler Synchrotron (COSY) to scan momenta near 970MeV/c. This entails a scan of the spin-precession frequency. At resonance between the spin-precession frequency of deuterons and the ALP-induced electric dipole moment (EDM) oscillation frequency, there is an accumulation of the polarization component out of the ring plane. Since the axion frequency is unknown, the momentum of the beam and, consequently, the spin-precession frequency are ramped to search for a vertical polarization change that occurs when the resonance is crossed. At COSY, four beam bunches with different polarization directions are used to make sure that no resonance is missed because of the unknown relative phase between the polarization precession and the axion or ALP field. A frequency window of 1.5 kHz width around the spin-precession frequency of 121 kHz is scanned. We describe the experimental procedure and a test of the methodology with the help of a radio-frequency Wien filter located on the COSY ring. No ALP resonance is observed. As a consequence, an upper limit of the oscillating EDM component of the deuteron as well as its axion coupling constants are provided.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego