Yeung Lam - Academia.edu (original) (raw)

Papers by Yeung Lam

Research paper thumbnail of Use of a digital camera to estimate heterogeneous temperatures and heat flux in a forest understory soil

Background/Question/Methods Soil temperature drives microbial activity, plant germination, rootin... more Background/Question/Methods Soil temperature drives microbial activity, plant germination, rooting, and CO2 fluxes. Soil energy balance is also used in calculations of eddy flux measurements. Because soil surface temperatures can be spatial heterogeneous due to uneven heating from partial shading by an overstory, calculating soil energy balances over large areas and predicting sub-surface temperatures in a forested environment is difficult. Using the analytical models for homogeneously conductive material introduces errors when trying to accurately predict sub-surface temperatures from those at the surface. However, complex patterns of soil surface and sub-surface temperatures due to partial shading by an overstory can be modeled using after the decomposition of the signals into a series of simpler sine waves of different frequencies. Simultaneously, the use of a digital camera to detect areas of solar radiation, coupled with measurements of air temperature, can be used to predict s...

Research paper thumbnail of A wireless biomedical instrument for evidence-based tissue wound characterization

Wireless Health 2010 on - WH '10, 2010

Patients' skin integrity has long been an issue of concern in nursing homes and ... more Patients' skin integrity has long been an issue of concern in nursing homes and hospitals. Overall incidence of pressure ulcers for hospitalized patients is as high as 50%. The estimated cost of treating pressure ulcers ranges from 5,000to5,000 to 5,000to40,000 for each ulcer, depending on severity. A smart compact capacitive sensing wireless handheld system is presented which measures Sub-Epidermal Moisture (SEM) as a mean to detect and monitor early symptoms of ulcer development. The system was successfully verified in trials with 30 volunteers and is currently deployed for clinical trials in four nursing homes.

Research paper thumbnail of Wearable sensor for continuously vigilant spatial and depth-resolved perfusion imaging

Proceedings of the conference on Wireless Health - WH '12, 2012

ABSTRACT Direct characterization of blood perfusion in tissue is critical to a broad spectrum of ... more ABSTRACT Direct characterization of blood perfusion in tissue is critical to a broad spectrum of applications in assessing circulatory disorders, wound conditions and ensuring outcomes of treatment. The rapid evolution of these conditions and their great risk for subjects require a continuously vigilant monitoring technology. This paper presents a wireless health platform providing the first wearable blood perfusion imager. This system, the Perfusion Oxygenation Monitor (POM), introduces sensing diversity by combining array methods and multispectral methods, as well as sensor and emitter distribution and operation scheduling. The principles of photoplethysmographic (PPG) sensing exploited by new methods will enable care providers to actively monitor blood perfusion at multiple anatomical sites for characterization and tracking of perfusion critical to tissue health, wound status and healing, formation of pressure ulcers, and circulation conditions. The POM system is described here along with its experimental validation. Experimental validation has been provided by a direct probing method based on physiological thermoregulatory response that induces perfusion change and is directly measured by POM. The demonstration of the POM system will also be supplemented by an analysis of the end to end system including sensor information processing, feature detection, Wireless Health data transport, and archive structure.

Research paper thumbnail of Human assisted robotic team campaigns for aquatic monitoring

Journal of Field Robotics, 2007

Large-scale environmental sensing, e.g., understanding microbial processes in an aquatic ecosyste... more Large-scale environmental sensing, e.g., understanding microbial processes in an aquatic ecosystem, requires coordination across a multidisciplinary team of experts working closely with eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. a robotic sensing and sampling system. We describe a human-robot team that conducted an aquatic sampling campaign in Lake Fulmor, San Jacinto Mountains Reserve, California during three consecutive site visits (May 9-11, June 19-22, and August 28-31, 2006). The goal of the campaign was to study the behavior of phytoplankton in the lake and their relationship to the underlying physical, chemical, and biological parameters. Phytoplankton form the largest source of oxygen and the foundation of the food web in most aquatic ecosystems. The reported campaign consisted of three system deployments spanning four months. The robotic system consisted of two subsystems-NAMOS (networked aquatic microbial observing systems) comprised of a robotic boat and static buoys, and NIMS-RD (rapidly deployable networked infomechanical systems) comprised of an infrastructure-supported tethered robotic system capable of high-resolution sampling in a two-dimensional cross section (vertical plane) of the lake. The multidisciplinary human team consisted of 25 investigators from robotics, computer science, engineering, biology, and statistics.We describe the lake profiling campaign requirements, the robotic systems assisted by a human team to perform high fidelity sampling, and the sensing devices used during the campaign to observe several environmental parameters. We discuss measures taken to ensure system robustness and quality of the collected data. Finally, we present an analysis of the data collected by iteratively adapting our experiment design to the observations in the sampled environment. We conclude with the plans for future deployments.

Research paper thumbnail of Fine-Scale Patterns of Soil and Plant Surface Temperatures in an Alpine Fellfield Habitat, White Mountains, California

Arctic, Antarctic, and Alpine Research, 2012

Research paper thumbnail of Forest understory soil temperatures and heat flux calculated using a Fourier model and scaled using a digital camera

Agricultural and Forest Meteorology, 2010

2010. Forest understory soil temperatures and heat flux calculated using a Fourier model and scal... more 2010. Forest understory soil temperatures and heat flux calculated using a Fourier model and scaled using a digital camera. Agricultural and Forest Meteorology 150: 640-649. Published Web Location: http://dx.

Research paper thumbnail of A wireless biomedical handheld instrument for evidence-based detection of pressure ulcers

Proceedings of the 2nd Conference on Wireless Health - WH '11, 2011

Pressure Ulcer (PU) incidence leads to considerable risk, in particular for the frail elderly, an... more Pressure Ulcer (PU) incidence leads to considerable risk, in particular for the frail elderly, and a large national healthcare treatment cost. Evidence-based methods for assuring the health and safety of patients are urgently needed. Recent clinical trials have demonstrated that sub-epidermal moisture (SEM) present in tissue may be measured by interrogation of tissue dielectric properties and are associated with the

Research paper thumbnail of Use of a digital camera to estimate heterogeneous temperatures and heat flux in a forest understory soil

Background/Question/Methods Soil temperature drives microbial activity, plant germination, rootin... more Background/Question/Methods Soil temperature drives microbial activity, plant germination, rooting, and CO2 fluxes. Soil energy balance is also used in calculations of eddy flux measurements. Because soil surface temperatures can be spatial heterogeneous due to uneven heating from partial shading by an overstory, calculating soil energy balances over large areas and predicting sub-surface temperatures in a forested environment is difficult. Using the analytical models for homogeneously conductive material introduces errors when trying to accurately predict sub-surface temperatures from those at the surface. However, complex patterns of soil surface and sub-surface temperatures due to partial shading by an overstory can be modeled using after the decomposition of the signals into a series of simpler sine waves of different frequencies. Simultaneously, the use of a digital camera to detect areas of solar radiation, coupled with measurements of air temperature, can be used to predict s...

Research paper thumbnail of A wireless biomedical instrument for evidence-based tissue wound characterization

Wireless Health 2010 on - WH '10, 2010

Patients' skin integrity has long been an issue of concern in nursing homes and ... more Patients' skin integrity has long been an issue of concern in nursing homes and hospitals. Overall incidence of pressure ulcers for hospitalized patients is as high as 50%. The estimated cost of treating pressure ulcers ranges from 5,000to5,000 to 5,000to40,000 for each ulcer, depending on severity. A smart compact capacitive sensing wireless handheld system is presented which measures Sub-Epidermal Moisture (SEM) as a mean to detect and monitor early symptoms of ulcer development. The system was successfully verified in trials with 30 volunteers and is currently deployed for clinical trials in four nursing homes.

Research paper thumbnail of Wearable sensor for continuously vigilant spatial and depth-resolved perfusion imaging

Proceedings of the conference on Wireless Health - WH '12, 2012

ABSTRACT Direct characterization of blood perfusion in tissue is critical to a broad spectrum of ... more ABSTRACT Direct characterization of blood perfusion in tissue is critical to a broad spectrum of applications in assessing circulatory disorders, wound conditions and ensuring outcomes of treatment. The rapid evolution of these conditions and their great risk for subjects require a continuously vigilant monitoring technology. This paper presents a wireless health platform providing the first wearable blood perfusion imager. This system, the Perfusion Oxygenation Monitor (POM), introduces sensing diversity by combining array methods and multispectral methods, as well as sensor and emitter distribution and operation scheduling. The principles of photoplethysmographic (PPG) sensing exploited by new methods will enable care providers to actively monitor blood perfusion at multiple anatomical sites for characterization and tracking of perfusion critical to tissue health, wound status and healing, formation of pressure ulcers, and circulation conditions. The POM system is described here along with its experimental validation. Experimental validation has been provided by a direct probing method based on physiological thermoregulatory response that induces perfusion change and is directly measured by POM. The demonstration of the POM system will also be supplemented by an analysis of the end to end system including sensor information processing, feature detection, Wireless Health data transport, and archive structure.

Research paper thumbnail of Human assisted robotic team campaigns for aquatic monitoring

Journal of Field Robotics, 2007

Large-scale environmental sensing, e.g., understanding microbial processes in an aquatic ecosyste... more Large-scale environmental sensing, e.g., understanding microbial processes in an aquatic ecosystem, requires coordination across a multidisciplinary team of experts working closely with eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. a robotic sensing and sampling system. We describe a human-robot team that conducted an aquatic sampling campaign in Lake Fulmor, San Jacinto Mountains Reserve, California during three consecutive site visits (May 9-11, June 19-22, and August 28-31, 2006). The goal of the campaign was to study the behavior of phytoplankton in the lake and their relationship to the underlying physical, chemical, and biological parameters. Phytoplankton form the largest source of oxygen and the foundation of the food web in most aquatic ecosystems. The reported campaign consisted of three system deployments spanning four months. The robotic system consisted of two subsystems-NAMOS (networked aquatic microbial observing systems) comprised of a robotic boat and static buoys, and NIMS-RD (rapidly deployable networked infomechanical systems) comprised of an infrastructure-supported tethered robotic system capable of high-resolution sampling in a two-dimensional cross section (vertical plane) of the lake. The multidisciplinary human team consisted of 25 investigators from robotics, computer science, engineering, biology, and statistics.We describe the lake profiling campaign requirements, the robotic systems assisted by a human team to perform high fidelity sampling, and the sensing devices used during the campaign to observe several environmental parameters. We discuss measures taken to ensure system robustness and quality of the collected data. Finally, we present an analysis of the data collected by iteratively adapting our experiment design to the observations in the sampled environment. We conclude with the plans for future deployments.

Research paper thumbnail of Fine-Scale Patterns of Soil and Plant Surface Temperatures in an Alpine Fellfield Habitat, White Mountains, California

Arctic, Antarctic, and Alpine Research, 2012

Research paper thumbnail of Forest understory soil temperatures and heat flux calculated using a Fourier model and scaled using a digital camera

Agricultural and Forest Meteorology, 2010

2010. Forest understory soil temperatures and heat flux calculated using a Fourier model and scal... more 2010. Forest understory soil temperatures and heat flux calculated using a Fourier model and scaled using a digital camera. Agricultural and Forest Meteorology 150: 640-649. Published Web Location: http://dx.

Research paper thumbnail of A wireless biomedical handheld instrument for evidence-based detection of pressure ulcers

Proceedings of the 2nd Conference on Wireless Health - WH '11, 2011

Pressure Ulcer (PU) incidence leads to considerable risk, in particular for the frail elderly, an... more Pressure Ulcer (PU) incidence leads to considerable risk, in particular for the frail elderly, and a large national healthcare treatment cost. Evidence-based methods for assuring the health and safety of patients are urgently needed. Recent clinical trials have demonstrated that sub-epidermal moisture (SEM) present in tissue may be measured by interrogation of tissue dielectric properties and are associated with the