16 research outputs found
Evaluation of pulse transit time for different sensing methodologies of arterial waveforms.
We perform a novel comparative analysis between optically and mechanically derived pulse transit time (PTT), which is a universally employed technique for cuffless blood pressure (BP) estimation. Two inline photoplethysmogram (PPG) sensors were placed at the distal and proximal phalanxes of the index finger, and two finger ballistocardiogram (BPP) sensors were wrapped on top of the PPG sensors fixture around the phalanxes of the index finger. The stacking of the BPP sensor over the PPG sensor provided vertical spatial alignment for same location acquisition of the blood flow waveform through the radial artery. The analysis of variance (ANOVA) between PTT derived from the PPG and BPP sensors resulted in a statistically significant difference at p < 0.05. The PTT derived from the BPP sensors showed higher values (17.8 milliseconds on average) than the PTT derived from the PPG sensors. Higher accuracy PTT values will improve the estimation of cuffless BP and thus has the potential to revolutionize the technology
Isothermal Fatigue and Creep-Fatigue Interaction Behavior of Nickel-Base Directionally Solidified Superalloy
The creep-fatigue interaction in directionally solidified nickel-base superalloy was analyzed with the modified Chaboche-based unified viscoplasticity constitutive model. The model features the anisotropic material behavior, hardening/ softening, and stress relaxation. Simple low-cyclic fatigue and specified hold time experiments were conducted on a directionally solidified superalloy (DZ125) at temperatures over 760Β°C. The material parameters were optimized considering its tensile, cyclic and creep behavior with the LevenbergβMarquardt optimization procedure. The model was constructed in FORTRAN and integrated in FEA software UMAT/ABAQUS. The results show that experimental and simulated hysteresis loop size/shape, peak stresses, stress relaxation, and related areas are closely matched. The modified constitutive model was found to be instrumental for revealing the fatigue and creep-fatigue interaction behavior of such materials and can be used for practical applications.ΠΠ·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΠ΅ ΠΏΠΎΠ»Π·ΡΡΠ΅ΡΡΠΈ ΠΈ ΡΡΡΠ°Π»ΠΎΡΡΠΈ Π² ΡΡΠΏΠ΅ΡΡΠΏΠ»Π°Π²Π΅ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ Π½ΠΈΠΊΠ΅Π»Ρ, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠ³ΠΎ Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½Π½ΠΎΠΉ ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΠ·Π°ΡΠΈΠ΅ΠΉ, ΠΏΡΠΎΠ°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°Π½ΠΎ Ρ ΠΏΠΎΠΌΠΎΡΡΡ ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΡΠ½ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡΠ΅ΠΉ ΠΌΠΎΠ΄Π΅Π»ΠΈ Π²ΡΠ·ΠΊΠΎΠΏΠ»Π°ΡΡΠΈΡΠ½ΠΎΡΡΠΈ Π¨Π°Π±ΠΎΡΠ°. ΠΠΎΠ΄Π΅Π»Ρ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΠ΅Ρ Π°Π½ΠΈΠ·ΠΎΡΡΠΎΠΏΠ½ΠΎΠ΅ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΠ΅ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°, ΡΠΏΡΠΎΡΠ½Π΅Π½ΠΈΠ΅/ΡΠ°Π·ΡΠΏΡΠΎΡΠ½Π΅Π½ΠΈΠ΅ ΠΈ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΡ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ. ΠΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΡ ΠΏΠΎ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΌΠ°Π»ΠΎΡΠΈΠΊΠ»ΠΎΠ²ΠΎΠΉ ΡΡΡΠ°Π»ΠΎΡΡΠΈ ΠΈ Π²ΡΠ΅ΠΌΠ΅Π½ΠΈ ΠΏΡΠ΅Π±ΡΠ²Π°Π½ΠΈΡ Π²ΡΠΏΠΎΠ»Π½Π΅Π½Ρ Π½Π° ΡΡΠΏΠ΅ΡΡΠΏΠ»Π°Π²Π΅ (DZ125) ΠΏΡΠΈ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ°Ρ
Π²ΡΡΠ΅ 760Β°Π‘. ΠΠ°ΡΠ°ΠΌΠ΅ΡΡΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° ΠΎΠΏΡΠΈΠΌΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Ρ Ρ ΡΡΠ΅ΡΠΎΠΌ Π΅Π³ΠΎ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΠΏΡΠΈ ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΠΈ, ΡΠΈΠΊΠ»ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π½Π°Π³ΡΡΠ·ΠΊΠ΅ ΠΈ ΠΏΠΎΠ»Π·ΡΡΠ΅ΡΡΠΈ ΠΏΡΠΈ ΠΏΠΎΠΌΠΎΡΠΈ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ ΠΠ΅Π²Π΅Π½Π±Π΅ΡΠ³Π°βΠΠ°ΡΠΊΠ²Π°ΡΠ΄ΡΠ°. ΠΠΎΠ΄Π΅Π»Ρ ΠΏΠΎΡΡΡΠΎΠ΅Π½Π° Π½Π° ΡΠ·ΡΠΊΠ΅ Π€ΠΠ Π’Π ΠΠ ΠΈ ΠΈΠ½ΡΠ΅Π³ΡΠΈΡΠΎΠ²Π°Π½Π° Π² ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ FEΠ UMAT/ABAQUS. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΡΠ΅ ΠΈ ΠΌΠΎΠ΄Π΅Π»ΡΠ½ΡΠ΅ ΡΠ°Π·ΠΌΠ΅ΡΡ/ ΡΠΎΡΠΌΠ° ΠΏΠ΅ΡΠ»ΠΈ Π³ΠΈΡΡΠ΅ΡΠ΅Π·ΠΈΡΠ°, ΠΏΠΈΠΊΠΎΠ²ΡΠ΅ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΡ, ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΡ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ ΠΈ ΠΈΡ
ΠΎΠ±Π»Π°ΡΡΡ Π½Π°Ρ
ΠΎΠ΄ΡΡΡΡ Π² ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΠΈΠΈ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΠΌΠΎΠ΄ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΡΡ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡΡΡ ΠΌΠΎΠ΄Π΅Π»Ρ ΡΠ΅Π»Π΅ΡΠΎΠΎΠ±ΡΠ°Π·Π½ΠΎ ΠΏΡΠΈΠΌΠ΅Π½ΡΡΡ ΠΏΡΠΈ Π°Π½Π°Π»ΠΈΠ·Π΅ ΡΡΡΠ°Π»ΠΎΡΡΠΈ ΠΈ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΏΠΎΠ»Π·ΡΡΠ΅ΡΡΠΈ ΠΈ ΡΡΡΠ°Π»ΠΎΡΡΠΈ ΠΏΠΎΠ΄ΠΎΠ±Π½ΡΡ
ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ², ΠΎΠ½Π° ΠΌΠΎΠΆΠ΅Ρ ΡΠ°ΠΊΠΆΠ΅ Π½Π°ΠΉΡΠΈ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅