Mechanical Engineering - Research Publications
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ItemFeasibility and performance analysis of hybrid ground source heat pump systems in fourteen cities(PERGAMON-ELSEVIER SCIENCE LTD, 2021-11-01)Ground source heat pump systems (GSHP) for residential building heating, cooling, and hot water are highly energy efficient but capital intensive when sized for peak demands. The use of supplemental sources of energy with GSHP systems enables improved life-cycle economics through the reduction in the size and cost of the GSHP components. This paper investigates the life-cycle economics of hybrid solar-assisted ground source heat pump systems (SAGSHP) using simulations validated from field data. The economics and optimal sizing of SAGSHP systems for heating dominant climates in four locations in Australia and ten locations elsewhere are evaluated in order to explore the suitability and relative merits of SAGSHP systems in a range of heating dominant climates. In locations having high or moderate levels of solar irradiation, high electricity prices, and high or moderate gas prices, SAGSHP systems are shown to have the lowest life cycle cost amongst alternatives, with predicted savings of up to 30%.
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ItemImpact of Industry 4.0 adoption on workload demands in contact centers(WILEY, 2022-09)Abstract This paper examines the impact of Industry 4.0 (I4.0) technologies on employees workload in contact centers. For that, we adopted the NASA task load index questionnaire to assess the workload of 100 employees from different contact centers in India that have been adopting I4.0 technologies. The collected data is analyzed through multivariate techniques. This study is grounded on concepts from the multiple resource theory. Our findings indicate positive and negative effects of I4.0 on employees workload, conditioned on the adopted technologies (i.e., Internet‐of‐Things, cloud computing, big data, machine learning/artificial intelligence, remote monitoring, and wireless sensors) and workload dimensions considered (i.e., mental demand, physical demand, temporal demand, overall performance, effort, and frustration level). Identifying I4.0's impacts on employees workload allows planning of managerial efforts to mitigate potential issues while setting clear expectations related to the digital transformation of contact centers' processes and services.
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ItemVented Individual Patient (VIP) Hoods for the Control of Infectious Airborne Diseases in Healthcare Facilities.(Elsevier BV, 2022-08)By providing a means of separating the airborne emissions of patients from the air breathed by healthcare workers (HCWs), vented individual patient (VIP) hoods, a form of local exhaust ventilation (LEV), offer a new approach to reduce hospital-acquired infection (HAI). Results from recent studies have demonstrated that, for typical patient-emitted aerosols, VIP hoods provide protection at least equivalent to that of an N95 mask. Unlike a mask, hood performance can be easily monitored and HCWs can be alerted to failure by alarms. The appropriate use of these relatively simple devices could both reduce the reliance on personal protective equipment (PPE) for infection control and provide a low-cost and energy-efficient form of protection for hospitals and clinics. Although the development and deployment of VIP hoods has been accelerated by the coronavirus disease 2019 (COVID-19) pandemic, these devices are currently an immature technology. In this review, we describe the state of the art of VIP hoods and identify aspects in need of further development, both in terms of device design and the protocols associated with their use. The broader concept of individual patient hoods has the potential to be expanded beyond ventilation to the provision of clean conditions for individual patients and personalized control over other environmental factors such as temperature and humidity.
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ItemHealthy indoor air is our fundamental need: the time to act is now.(Wiley, 2022-12-12)
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ItemMETABOLIC COST AND MECHANICAL EFFICIENCY OF A NOVEL HANDLE-BASED DEVICE FOR WHEELCHAIR PROPULSION(FOUNDATION REHABILITATION INFORMATION, 2022-11)OBJECTIVE: To investigate differences in metabolic cost and gross mechanical efficiency of a novel handlebased wheelchair propulsion device and to compare its performance with conventional push-rim propulsion. DESIGN: Double-group comparative study between 2 different propulsion methods. PARTICIPANTS: Eight paraplegic individuals and 10 non-disabled persons. METHODS: Participants performed the same exercise using a push-rim device and the novel handle-based device on a wheelchair- based test rig. The exercise consisted of a combined submaximal and maximal test. Power output, oxygen uptake, ventilation, respiratory exchange ratio and heart rate were recorded continuously during the tests. Analysis of variance was performed to determine the effects of group, mode and on power output. RESULTS: Submaximal exercise resulted in a higher efficiency for the novel device and significant main effects of propulsion mode on all investigated parameters, except heart rate. On the respiratory exchange ratio, a significant interaction effect was found for both mode and group. The maximal exercise resulted in a higher peak power output and lower peak heart rate during propulsion using the handle-based device. A significant main effect on mode for mean peak power output, ventilation and heart rate was also observed. CONCLUSION: Wheelchair propulsion using the handle-based device resulted in lower physical responses and higher mechanical efficiency, suggesting that this novel design may be well suited for indoor use, thereby offering an attractive alternative to pushrim wheelchairs.
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ItemThe control and training of single motor units in isometric tasks are constrained by a common input signal(eLIFE SCIENCES PUBL LTD, 2022-06-07)Recent developments in neural interfaces enable the real-time and non-invasive tracking of motor neuron spiking activity. Such novel interfaces could provide a promising basis for human motor augmentation by extracting potentially high-dimensional control signals directly from the human nervous system. However, it is unclear how flexibly humans can control the activity of individual motor neurons to effectively increase the number of degrees of freedom available to coordinate multiple effectors simultaneously. Here, we provided human subjects (N = 7) with real-time feedback on the discharge patterns of pairs of motor units (MUs) innervating a single muscle (tibialis anterior) and encouraged them to independently control the MUs by tracking targets in a 2D space. Subjects learned control strategies to achieve the target-tracking task for various combinations of MUs. These strategies rarely corresponded to a volitional control of independent input signals to individual MUs during the onset of neural activity. Conversely, MU activation was consistent with a common input to the MU pair, while individual activation of the MUs in the pair was predominantly achieved by alterations in de-recruitment order that could be explained by history-dependent changes in motor neuron excitability. These results suggest that flexible MU recruitment based on independent synaptic inputs to single MUs is unlikely, although de-recruitment might reflect varying inputs or modulations in the neuron's intrinsic excitability.
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ItemPrinciples of human movement augmentation and the challenges in making it a reality(NATURE PORTFOLIO, 2022-03-15)Augmenting the body with artificial limbs controlled concurrently to one's natural limbs has long appeared in science fiction, but recent technological and neuroscientific advances have begun to make this possible. By allowing individuals to achieve otherwise impossible actions, movement augmentation could revolutionize medical and industrial applications and profoundly change the way humans interact with the environment. Here, we construct a movement augmentation taxonomy through what is augmented and how it is achieved. With this framework, we analyze augmentation that extends the number of degrees-of-freedom, discuss critical features of effective augmentation such as physiological control signals, sensory feedback and learning as well as application scenarios, and propose a vision for the field.
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ItemInteraction with a reactive partner improves learning in contrast to passive guidance(NATURE PORTFOLIO, 2022-09-22)Many tasks such as physical rehabilitation, vehicle co-piloting or surgical training, rely on physical assistance from a partner. While this assistance may be provided by a robotic interface, how to implement the necessary haptic support to help improve performance without impeding learning is unclear. In this paper, we study the influence of haptic interaction on the performance and learning of a shared tracking task. We compare in a tracking task the interaction with a human partner, the trajectory guidance traditionally used in training robots, and a robot partner yielding human-like interaction. While trajectory guidance resulted in the best performance during training, it dramatically reduced error variability and hindered learning. In contrast, the reactive human and robot partners did not impede the adaptation and allowed the subjects to learn without modifying their movement patterns. Moreover, interaction with a human partner was the only condition that demonstrated an improvement in retention and transfer learning compared to a subject training alone. These results reveal distinctly different learning behaviour in training with a human compared to trajectory guidance, and similar learning between the robotic partner and human partner. Therefore, for movement assistance and learning, algorithms that react to the user's motion and change their behaviour accordingly are better suited.