Matching Items (12)
Description
Determining the characteristics of an object during a grasping task requires a combination of mechanoreceptors in the muscles and fingertips. The width of a person's finger aperture during the grasp may affect the accuracy of how that person determines hardness, as well. These experiments aim to investigate how an individual perceives hardness amongst a gradient of varying hardness levels. The trend in the responses is assumed to follow a general psychometric function. This will provide information about subjects' abilities to differentiate between two largely different objects, and their tendencies towards guess-chances upon the presentation of two similar objects. After obtaining this data, it is then important to additionally test varying finger apertures in an object-grasping task. This will allow an insight into the effect of aperture on the obtained psychometric function, thus ultimately providing information about tactile and haptic feedback for further application in neuroprosthetic devices. Three separate experiments were performed in order to test the effect of finger aperture on object hardness differentiation. The first experiment tested a one-finger pressing motion among a hardness gradient of ballistic gelatin cubes. Subjects were asked to compare the hardness of one cube to another, which produced the S-curve that accurately portrayed the psychometric function. The second experiment utilized the Phantom haptic device in a similar setup, using the precision grip grasping motion, instead. This showed a more linear curve; the percentage reported harder increased as the hardness of the second presented cube increased, which was attributed to both the experimental setup limitations and the scale of the general hardness gradient. The third experiment then progressed to test the effect of three finger apertures in the same experimental setup. By providing three separate testing scenarios in the precision grip task, the experiment demonstrated that the level of finger aperture has no significant effect on an individual's ability to perceive hardness.
ContributorsMaestas, Gabrielle Elise (Author) / Helms Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2015-05
Description
Currently, assistive robots and prosthesis have a difficult time giving and receiving objects to and from humans. While many attempts have been made to program handover scenarios into robotic control algorithms, the algorithms are typically lacking in at least one important feature: intuitiveness, safety, and efficiency. By performing a study to better understand human-to-human handovers, we observe trends that could inspire controllers for object handovers with robots. Ten pairs of human subjects handed over a cellular phone-shaped, instrumented object using a key pinch while 3D force and motion tracking data were recorded. It was observed that during handovers, humans apply a compressive force on the object and employ linear grip force to load force ratios when two agents are grasping an object (referred to as the "mutual grasp period"). Results also suggested that object velocity during the mutual grasp period is driven by the receiver, while the duration of the mutual grasp period is driven by the preference of the slowest agent involved in the handover. Ultimately, these findings will inspire the development of robotic handover controllers to advance seamless physical interactions between humans and robots.
ContributorsChang, Eric (Author) / Helms Tillery, Stephen (Thesis director) / Santos, Veronica (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
Description
Central to current conceptions concerning the function of the nervous system is the consideration of how it manages to maintain precise control for repetitive tasks such as reaching, given the extensive observable mechanical degrees of freedom. Especially in the upper extremities, there are an infinite number of orientations (degrees of freedom) that can produce the same ultimate outcome. Consider, for example, a man in a seated position pointing to an object on a table with his index finger: even if we vastly simplify the mechanics involved in that action by considering three principle joints - the shoulder, elbow, and wrist - there are an infinite number of upper arm orientations that would result in the same position of the man's index finger in three-dimensional space. It has been hypothesized that the central nervous system is capable of simplifying reaching tasks by organizing the DOFs; this suggests that repetitive, simple tasks such as reaching can be planned, that the variability in repetitive tasks is minimized, and that the central nervous system is capable of increasing stability by instantaneously resisting perturbations. Previous literature indicates that variability is decreased and stability increased in trained upper extremity movement. In this study, mechanical discrepancies between violinists of varying levels of experience were identified. It was hypothesized that variability in the positional error (deviation from an expected line of motion) and velocity of the bow, as well as the produced variability in resultant elbow angles, would decrease with increasing proficiency, and that training would have no observable effect on average peak bow velocity. Data acquisition was accomplished by constructing LED triads and implementing a PhaseSpace 3D Motion Capture system. While the positional variance and peak velocity magnitude of the bow appeared unaffected by training (p >> 0.05), more advanced players demonstrated significantly higher variability in bow velocity (p << 0.001). As such, it can be concluded that repetitive training does manifest in changes in variability; however, further investigation is required to reveal the nature of these changes.
ContributorsCulibrk, Robert (Author) / Helms Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The purpose of this experiment is to study whether there is a difference in applied finger force between violinists of different skill proficiencies. It has been hypothesized that more experienced violinists will apply less force during play in their thumb and index fingers. It was found that there was significant difference in the peak forces applied by the index finger, thumb, and grip (p < 0.05) in all groups except beginner and intermediate violinists in peak thumb force. Significant differences were also found in the continuous force applied by the index finger and grip as well as the standard deviation of the continuous force applied by the thumb (p < 0.05). Additionally, there were no significant differences in the correlation between continuous applied index finger and thumb forces or latency in index and thumb force between different levels or proficiencies (p > 0.05). Due to these results, the hypothesis could not be fully accepted signifying that further testing must be performed.
ContributorsNguyen, Andre (Author) / Helms Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Lack of proprioceptive feedback is one cause for the high upper-limb prosthesis abandonment rate. The lack of environmental interaction normalcy from unreliable proprioception creates dissatisfaction among prosthesis users. The purpose of this experiment is to investigate the effects of square breathing on learning to navigate without reliable proprioception. Square breathing is thought to influence the vagus nerve which is linked to increased learning rates. In this experiment, participants were instructed to reach toward targets in a semi-immersive virtual reality environment. Directional error, peak velocity, and peak acceleration of the reaching hand were investigated before and after participants underwent square breathing training. As the results of<br/>this experiment are inconclusive, further investigation needs to be done with larger sample sizes and examining unperturbed data to fully understand the effects of square breathing on learning new motor strategies in unreliable proprioceptive conditions.
ContributorsBonar, Sonja Marie (Author) / Helms Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / VanGuilder, Paul (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description在目前中国资本市场中，风险资本偏好于科创企业，而科创企业的重要创新产出——专利，是衡量其创新程度的重要指标。本文以上市公司和非上市公司样本为研究标的，分别探讨其专利数量、质量对股权融资的影响效应。从理论意义来看，目前关于专利与企业价值关系的研究，大多集中在上市公司。此外，对上市公司的研究层面及内容，大多关注一个维度，专利要素内容相对单一。另外，既有研究对专利与企业绩效之间关系研究较多，对于专利与融资估值之间关系的关注较少。为此，本文从非上市科创企业入手，从专利的数量、质量两个维度对其股权融资进行整体分析、研究。从实践意义来看，本文通过收集非上市公司、科创板上市公司的专利、财务等数据，进行分析，得出专利数量、质量与融资估值之间的关系，从而对预备在科创板上市的公司提供可借鉴的内容。
基于此，本文以综合质性研究和定量实证研究两种研究方法，对专利数量、质量与创新型企业的融资估值关系进行了分析。本文以3家非上市公司和3家上市公司为研究标的，取得初步结论后，以非上市公司和上市公司数据为样本，进行对比分析，得出主要研究结论如下：
1、无论是上市公司还是非上市公司，专利数量与融资估值之间存在着显著的倒U型关系。
2、无论是上市公司还是非上市公司，专利质量与融资估值之间存在着显著的正相关关系。
3、将上市公司与非上市公司进行对比，在专利数量与融资估值的关系方面，上市公司的专利数量的临界值比非上市公司更高，且在跨过临界值之后，专利数量的增减对于非上市公司融资估值的影响会比上市公司的影响更大。
4、从企业IPO前的专利情况与企业IPO后第一年的融资估值之间的关系来看，企业IPO前的专利数量与专利质量与融资估值之间都存在显著的正相关的关系。说明对于科技创新能力较强的企业来说，在企业IPO前的积累阶段，企业的专利数量越多，专利质量越高，对于企业的融资估值的促进作用越显著。
ContributorsWang, Hua (Author) / Shao, Benjamin (Thesis advisor) / Chang, Eric (Thesis advisor) / Zhu, Kevin (Committee member) / Arizona State University (Publisher)
Created2022
Description
Following a study conducted in 1991 supporting that kinesthetic information affects visual processing information when moving an arm in extrapersonal space, this research aims to suggest utilizing virtual-reality (VR) technology will lead to more accurate and faster data acquisition (Helms Tillery, et al.) [1]. The previous methods for conducting such research used ultrasonic systems of ultrasound emitters and microphones to track distance from the speed of sound. This method made the experimentation process long and spatial data difficult to synthesize. The purpose of this paper is to show the progress I have made in the efforts to capture spatial data using VR technology to enhance the previous research that has been done in the field of neuroscience. The experimental setup was completed using the Oculus Quest 2 VR headset and included hand controllers. The experiment simulation was created using Unity game engine to build a 3D VR world which can be used interactively with the Oculus. The result of this simulation allows the user to interact with a ball in the VR environment without seeing the body of the user. The VR simulation is able to be used in combination with real-time motion capture cameras to capture live spatial data of the user during trials, though spatial data from the VR environment has not been able to be collected.
ContributorsSyed, Anisa (Author) / Helms-Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2022-05
Description通过引入国有资本提升融资能力、克服制度约束是民营企业提升创新水平的重要举措，在现有研究聚焦于民营企业创新数量的基础上，本文引入了代表不同创新程度和创新类型的利用式创新和探索式创新，分析民营企业引入国有资本将如何影响其两种不同的创新行为，以及公司治理、关键人力资本激励以及市场环境等影响企业成长的关键因素在其中发挥了何种调节效果。本文收集了2008至2019年中国A股上市企业的数据，利用多期DID双重差分模型进行假设验证，得出以下结论：其一，民营企业引入国有资本将提升其利用式创新，但降低了探索式创新。其二，高管团队异质性、环境不确定性能够有效缓解国有资本对探索式创新的不利影响，提升企业探索式创新水平，并且不会降低企业的利用式创新。股权激励在提升探索式创新的同时，会降低企业利用式创新。其三，国有资本引入与市场化发展水平具有替代作用，导致市场化发展水平较高地区的企业在引入国有资本后，更倾向于利用政治关联和资源优势获利，而同时降低企业利用式创新和探索式创新。其四，国有资本引入后的控制权变化能显著提升企业的利用式创新，但对探索式创新没有显著影响。
本文揭示了民营企业引入国有资本对其双元创新的影响，以及探索了国有资本引入背景下，企业提升探索式创新的关键因素，丰富了民营企业创新能力、混合所有制改革以及正式制度与非正式制度交互等相关的内容，为相应实践提供一定启示。
ContributorsChen, Feng (Author) / Pei, Ker-Wei (Thesis advisor) / Jiang, Zhan (Thesis advisor) / Chang, Eric (Committee member) / Arizona State University (Publisher)
Created2023
Description
Previously accomplished research examined sensory integration between upper limb proprioception and tactile sensation. The active proprioceptive-tactile relationship points towards an opportunity to examine neuromodulation effects on sensory integration with respect to proprioceptive error magnitude and direction. Efforts to improve focus and attention during upper limb proprioceptive tasks results in a decrease of proprioceptive error magnitudes and greater endpoint accuracy. Increased focus and attention can also be correlated to neurophysiological activity in the Locus Coeruleus (LC) during a variety of mental tasks. Through non-invasive trigeminal nerve stimulation, it may be possible to affect the activity of the LC and induce improvements in arousal and attention that would assist in proprioceptive estimation. The trigeminal nerve projects to the LC through the mesencephalic nucleus of the trigeminal complex, providing a pathway similar to the effects seen from vagus nerve stimulation. In this experiment, the effect of trigeminal nerve stimulation (TNS) on proprioceptive ability is evaluated by the proprioceptive estimation error magnitude and direction, while LC activation via autonomic pathways is indirectly measured using pupil diameter, pupil recovery time, and pupil velocity. TNS decreases proprioceptive error magnitude in 59% of subjects, while having no measurable impact on proprioceptive strategy. Autonomic nervous system changes were observed in 88% of subjects, with mostly parasympathetic activation and a mixed sympathetic effect.
ContributorsOrthlieb, Gerrit Chi Luk (Author) / Helms-Tillery, Stephen (Thesis advisor) / Tanner, Justin (Committee member) / Buneo, Christopher (Committee member) / Arizona State University (Publisher)
Created2019
Description中国基金行业经过20多年的发展，基金产品数量和管理资产规模稳步大幅增长。但是在行业快速发展的同时，大多数投资者并没有赚到钱或者盈利体验不好：根据中国证券投资基金业协会2016年公布的数据，自投资基金开始运作以来，盈利的投资者占比为30.9％，而亏损的投资者达到45.3％，特别是权益类基金，普遍存在着基金产品长期业绩不错，但多数个人投资者投资回报不佳，导致权益类基金的规模近十多年持续不断萎缩。
本文根据市场有效性理论与行为金融学、交易反馈策略等理论，结合某大型基金公司过去16年累积的权益类基金投资者的日度交易数据，对投资者投资基金的交易行为特别是持有时间与投资回报的相关关系进行统计分析，验证投资期限与投资回报之间的相关关系。同时，研究投资者在不同交易结构下的申赎行为对投资回报的影响；以及投资者选择不同特征的基金产品对投资回报的影响和投资者持有基金期间的市场波动率对于投资回报的影响。
本文在实证研究的部分将通过数据分析验证理论模型，具体揭示不同因素（持有基金产品时间、申购赎回周期、基金经理换手率、大盘波动率、Jensen指数、基金资产规模、基金经理管理经验、基金经理更换频率等）与投资回报的相关关系。在此基础上，结合相关理论和实践背景，分析在不同情形下，基金投资者可以采取什么样的交易策略、应该重点关注基金产品的哪些指标，来调整自身的投资行为，提升投资回报；或者基金管理人可以通过哪些方式来帮助投资者采取正确的投资行为。
本文研究的意义在于利用大量个人投资者的日度交易数据，去探讨其交易行为与策略对投资回报的影响，剖析基金投资者难以赚钱的实际原因，从不同维度分析出现这种状况的多方面影响因素，从微观层面实现对基金投资者交易行为与基金投资回报研究这一课题在学术研究层次上的有效补充。并以此为依据，对基金管理公司、个人投资者、基金销售机构和监管层提出具有实践意义的建议，期望通过这些建议或措施逐渐改善基金投资者的投资回报。
本文根据市场有效性理论与行为金融学、交易反馈策略等理论，结合某大型基金公司过去16年累积的权益类基金投资者的日度交易数据，对投资者投资基金的交易行为特别是持有时间与投资回报的相关关系进行统计分析，验证投资期限与投资回报之间的相关关系。同时，研究投资者在不同交易结构下的申赎行为对投资回报的影响；以及投资者选择不同特征的基金产品对投资回报的影响和投资者持有基金期间的市场波动率对于投资回报的影响。
本文在实证研究的部分将通过数据分析验证理论模型，具体揭示不同因素（持有基金产品时间、申购赎回周期、基金经理换手率、大盘波动率、Jensen指数、基金资产规模、基金经理管理经验、基金经理更换频率等）与投资回报的相关关系。在此基础上，结合相关理论和实践背景，分析在不同情形下，基金投资者可以采取什么样的交易策略、应该重点关注基金产品的哪些指标，来调整自身的投资行为，提升投资回报；或者基金管理人可以通过哪些方式来帮助投资者采取正确的投资行为。
本文研究的意义在于利用大量个人投资者的日度交易数据，去探讨其交易行为与策略对投资回报的影响，剖析基金投资者难以赚钱的实际原因，从不同维度分析出现这种状况的多方面影响因素，从微观层面实现对基金投资者交易行为与基金投资回报研究这一课题在学术研究层次上的有效补充。并以此为依据，对基金管理公司、个人投资者、基金销售机构和监管层提出具有实践意义的建议，期望通过这些建议或措施逐渐改善基金投资者的投资回报。
ContributorsSu, Bo (Author) / Pei, Ker-Wei (Thesis advisor) / Yan, Hong (Thesis advisor) / Chang, Eric (Committee member) / Arizona State University (Publisher)
Created2020