Asymptotic Stability of a Class of Non-linear Singularly Perturbed Systems²     

Joe Hong Chow 《Journal of The Franklin Institute》1978,305(5):275-281

Sufficient conditions are obtained to guarantee the asymptotic stability of a class of non-linear singularly perturbed systems. A procedure for constructing a Lyapunov function for such a class of systems is given, and a clearly defined domain of attraction of the equilibrium is obtained. A stabilizing feedback control for such systems is also proposed.  相似文献   

Lumbar spinal loads and muscle activity during a golf swing   总被引：1，自引：0，他引：1  

Lim YT  Chow JW  Chae WS 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(2):197-211

This study estimated the lumbar spinal loads at the L4-L5 level and evaluated electromyographic (EMG) activity of right and left rectus abdominis, external and internal obliques, erector spinae, and latissimus dorsi muscles during a golf swing. Four super VHS camcorders and two force plates were used to obtain three-dimensional (3D) kinematics and kinetics of golf swings performed by five male collegiate golfers. Average EMG levels for different phases of golf swing were determined. An EMG-assisted optimization model was applied to compute the contact forces acting on the L4-L5. The results revealed a mean peak compressive load of over six times the body weight (BW) during the downswing and mean peak anterior and medial shear loads approaching 1.6 and 0.6 BW during the follow-through phases. The peak compressive load estimated in this study was high, but less than the corresponding value (over 8 BW) reported by a previous study. Average EMG levels of different muscles were the highest in the acceleration and follow-through phases, suggesting a likely link between co-contractions of paraspinal muscles and lumbar spinal loads.  相似文献   

Reliability of laser Doppler,near-infrared spectroscopy and Doppler ultrasound for peripheral blood flow measurements during and after exercise in the heat     

Hui C. Choo  Kazunori Nosaka  Jeremiah J. Peiffer  Mohammed Ihsan  Chow C. Yeo  Chris R. Abbiss 《Journal of sports sciences》2017,35(17):1715-1723

This study examined the test-retest reliability of near-infrared spectroscopy (NIRS), laser Doppler flowmetry (LDF) and Doppler ultrasound to assess exercise-induced haemodynamics. Nine men completed two identical trials consisting of 25-min submaximal cycling at first ventilatory threshold followed by repeated 30-s bouts of high-intensity (90% of peak power) cycling in 32.8 ± 0.4°C and 32 ± 5% relative humidity (RH). NIRS (tissue oxygenation index [TOI] and total haemoglobin [tHb]) and LDF (perfusion units [PU]) signals were monitored continuously during exercise, and leg blood flow was assessed by Doppler ultrasound at baseline and after exercise. Cutaneous vascular conductance (CVC; PU/mean arterial pressure (MAP)) was expressed as the percentage change from baseline (%CVC_BL). Coefficients of variation (CVs) as indicators of absolute reliability were 18.7–28.4%, 20.2–33.1%, 42.5–59.8%, 7.8–12.4% and 22.2–30.3% for PU, CVC, %CVC_BL, TOI and tHb, respectively. CVs for these variables improved as exercise continued beyond 10 min. CVs for baseline and post-exercise leg blood flow were 17.8% and 10.5%, respectively. CVs for PU, tHb (r² = 0.062) and TOI (r² = 0.002) were not correlated (P > 0.05). Most variables demonstrated CVs lower than the expected changes (35%) induced by training or heat stress; however, minimum of 10 min exercise is recommended for more reliable measurements.  相似文献   

Health care: Its symptoms     

Marilyn Chow 《Early Childhood Education Journal》1975,2(5):3-7

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秦始皇兵马俑博物馆室内含硫颗粒物的SEM-EDX研究     

胡塔峰  曹军骥  李旭祥  董俊刚  沈振兴 《中国科学院大学学报》2007,24(5):564-570

本文对秦始皇兵马俑博物馆室内采集的长短期降尘、大气悬浮颗粒物和彩绘漆层进行了SEM-EDX研究,在大气悬浮颗粒、短期和长期降尘中,含硫颗粒的粒径分别为0.9～22.8μm、1.0～29.0μm和1.2～37.7μm,多为石膏与粘土或石英以内部混合的状态存在。降尘中的附着型絮状硫酸钙多于大气悬浮颗粒物中,显示降尘和大气中的二氧化硫发生了累进的化学反应。彩绘漆层表面的坑和裂隙附近观察到原位生长的硫酸钙晶体,显示漆层材料或降尘颗粒物与大气二氧化硫之间的酸化学反应,可能是彩绘漆层表面受侵蚀形成微小坑和裂隙的原因之一。  相似文献   

Sensory organisation and reactive balance control of amateur rugby players: A cross-sectional study     

Gary C. C. Chow  Joanne W. Y. Chung  Ada W. W. Ma  Duncan J. Macfarlane 《European Journal of Sport Science》2017,17(4):400-406

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Changes in organisation of instep kicking as a function of wearing compression and textured materials     

Hosni Hasan  Keith Davids  Jia Yi Chow  Graham Kerr 《European Journal of Sport Science》2017,17(3):294-302

This study investigated effects of wearing compression garments and textured insoles on modes of movement organisation emerging during performance of lower limb interceptive actions in association football. Participants were six skilled (age?=?15.67?±?0.74 years) and six less-skilled (age?=?15.17?±?1.1 years) football players. All participants performed 20 instep kicks with maximum velocity in four randomly organised insoles and socks conditions, (a) Smooth Socks with Smooth Insoles (SSSI); (b) Smooth Socks with Textured Insoles (SSTI); (c) Compression Socks with Smooth Insoles (CSSI); and (d), Compression Socks with Textured Insoles (CSTI). Results showed that, when wearing textured and compression materials (CSSI condition), less-skilled participants displayed significantly greater hip extension and flexion towards the ball contact phase, indicating larger ranges of motion in the kicking limb than in other conditions. Less-skilled participants also demonstrated greater variability in knee–ankle intralimb (angle–angle plots) coordination modes in the CSTI condition. Findings suggested that use of textured and compression materials increased attunement to somatosensory information from lower limb movement, to regulate performance of dynamic interceptive actions like kicking, especially in less-skilled individuals.  相似文献   

The state of evidence for social and emotional learning: A contemporary meta-analysis of universal school-based SEL interventions     

Christina Cipriano  Michael J. Strambler  Lauren H. Naples  Cheyeon Ha  Megan Kirk  Miranda Wood  Kaveri Sehgal  Almut K. Zieher  Abigail Eveleigh  Michael McCarthy  Melissa Funaro  Annett Ponnock  Jason C. Chow  Joseph Durlak 《Child development》2023,94(5):1181-1204

This article provides a systematic review and meta-analysis of the current evidence for universal school-based (USB) social and emotional learning (SEL) interventions for students in kindergarten through 12th grade available from 2008 through 2020. The sample includes 424 studies from 53 countries, reflecting 252 discrete USB SEL interventions, involving 575,361 students. Results endorsed that, compared to control conditions, students who participate in USB SEL interventions experienced significantly improved skills, attitudes, behaviors, school climate and safety, peer relationships, school functioning, and academic achievement. Significant heterogeneity in USB SEL content, intervention features, context, and implementation quality moderated student experiences and outcomes. Strengths and limitations of this evidence and implications for future USB SEL research, policy, and practice are discussed.  相似文献   

Educational technology and educational reform     

Clement Chow 《Educational technology research and development : ETR & D》1987,35(4):245-247

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The Influence of Stigma on College Students' Attitudes Toward Online Video Counseling and Face‐to‐Face Counseling     

Matthew D. Bird  Graig M. Chow  Gily Meir  Jaison Freeman 《Journal of College Counseling》2019,22(3):256-269

The difference in attitudes toward online video counseling and face‐to‐face counseling and the relationship between stigma and these attitudes were investigated among a sample of 588 college students. Attitudes toward face‐to‐face counseling are more favorable compared with those toward online video counseling. However, self‐stigma does not influence attitudes toward online video counseling to the same extent as face‐to‐face counseling. Services delivered through online video counseling may be beneficial for those experiencing higher levels of stigma.  相似文献