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Active Control of Beams and Plates Using Spatially Distributed Transducers
Hubbard, Jr.,James E. 대한기계학회 1993 Korea - U. S. Vibration Engineering Seminar Vol.1 No.1
The application of distributed transducers to the active vibration control of beams and plates is investigated for general boundary conditions and non-uniform spatial distributions. An energy based analysis of distributed transducer design issues related to observation and control is presented. The analysis exploits mode symmetry and boundary integral representations of key parameters to choose appropriate spatial weightings for distributed sensors and actuators. The energy based approach also offers the possibility of formulating control laws without the necessity of modeling the plant in terms of its component vibrational modes. Experimental examples and results are presented.
A New Method for Estimating High-Frequency Radar Error Using Data from Central San Francisco Bay
Maxwell Hubbard,Donald Barrick,Newell Garfield,Jim Pettigrew,Carter Ohlmann,Matthew Gough 한국해양과학기술원 2013 Ocean science journal Vol.48 No.1
This study offers a new method for estimating High- Frequency (HF) radar surface current velocity error in data comparisons with other types of instrumentation. A new method is needed in order to remove the zero-mean random spatial and temporal fluctuations present in surface-current measurements from all sensors. Conventional methods for calculating radar error when comparing with another instrument have included their root mean square differences and scatter plots that provide correlation coefficient and slope/intercept of the regression line. It seems that a meaningful estimate of radar error should attempt to remove both sensors' zero mean random fluctuations, inasmuch as possible. We offer and compare a method that does this. The method was tested on data collected in the Central San Francisco Bay, where GPS surface-drifter deployments were conducted within the coverage of four 42 MHz radars over six days in October of 2008. Drifters were continuously deployed in these areas over the sampling days, providing 525 usable drifter measurements. Drifter and radar measurements were averaged into thirty-minute time bins. The three-day long-term averages from the sampling areas were then subtracted from the thirtyminute averages to remove biases associated with comparisons done with short, disjoint time-sample periods. These were then used to develop methods that give radar error or bias after the random fluctuations have been removed. Results for error estimates in this study are commensurate with others where random fluctuations have been filtered, suggesting they are valid. The estimated error for the radars in the SF Bay is low, ranging from -7.57 cm/s to 0.59 cm/s.
Original Article : Plyometrics and vibration: no clear winner on efficacy
( R Jeremy Hubbard ),( Jerrold S Petrofsky ),( Everett Lohman ),( Berk Lee ),( Donna Thorpe ) 물리치료재활과학회 2014 Physical therapy rehabilitation science Vol.3 No.2
Objective: Whole body vibration (WBV) and plyometrics are common training techniques which increase strength, blood flow, and lower body force and power. The effects these techniques have on sedentary population is unknown. It is our aim to assess the effectiveness of WBV and plyometrics on sedentary population. Design: Experimental study. Methods: Twenty-seven sedentary subjects were assigned to either the control group, jumping only group, or jumping with vibration group. Jump height (myotest or vertec), velocity, force, blood lactates, and rating of perceived exertion (RPE). Subjects were measured on the initial, seventh, and eighteenth visits. Control group attended measurements only. Jumping only and jumping with vibration groups performed jumping from a vibrating platform to a surface 7 1/2 inches higher for 3 bouts of 20 seconds. Each subject in jumping only and jumping with vibration groups attended three times per week for six weeks. Vibration was set at 40 Hz and 2-4 mm of displacement. Results: There was no significant change among groups in force, velocity, vertec height, and myotest height. However there was a significant increase in vertec height from initial to final measure (p<0.05) for jumping with vibration group. RPE was significantly higher between control group and jumping with vibration group after intervention (p<0.05). Conclusions: WBV with vibration increased jump height. Jumping with vibration group experienced increased exertion than for controls. WBV with plyometrics had no effect on force, velocity, blood lactates, or calculated jump height. Further studies controlling for initial measure of blood lactates and using an external focus may be necessary to elicit velocity, force and jump height changes.
Communication Qualities, Quantity, and Satisfaction in Newly Developing Relationships
Amy S. Ebesu Hubbard,Krystyna S. Aune,Hye Eun Lee 한국소통학회 2018 한국소통학보 Vol.17 No.4
이 연구는 새로 시작되는 관계의 시작에서부터 안정화된 단계에 소통을 종적으로 조사하였다. 65명의 연구 참여자는 각자의 파트너 와 새로 시작되는 인간 관계를 형성하여 소통의 변화를 초창기부터 8차례에 걸쳐 만남 후 소통에 대하여 설문에 응답하였다. 가설은 소 통의 양, 질과 만족도 사이의 정적인 관계를 예상하였고, 모든 가설 은 지지되었다. 추가적인 연구문제에서는 소통의 양과 질은 만족도 에 영향을 미치는 요소임을 밝혔다. 본 연구 결과는 대인관계 발전 이론에서 주장해온 초창기 대인 관계에서의 소통의 중요성이 관계 발전의 중요한 요소라는 기본 명세를 실증적으로 조사하여 그 근거 를 제시하였다. This study longitudinally examined perceptions of communication in newly developing relationships. This is the first investigation to directly focus on each interaction in the beginning stages of relationships and the communication changes that occur in that process. Individuals completed surveys with a new acquaintance for their initial eight interactions. Hypotheses predicted positive associations between perceptions of communication qualities, quantity, and satisfaction. All hypotheses were supported. Research questions examined perceived communication qualities and quantity as predictors of satisfaction. The results provided strong support for the fundamental proposition in theories of relational development about communication changes as relationships evolve as well as new insights into which aspects of communication may be especially crucial during the early development of relationships.