Optimization of multi-wavelength Photoplethysmographic for wearable heart rate acquisition

Photoplethysmographic is an optical measure technique for heart rate monitoring on the surface of the skin. PPG based wearable heart rate monitor has become popular in consumer targeted market. This thesis work is based on the PulseOn product development and the final implementation will be integrated into the PulseOn OHRM sensor product. Choice of the wavelength of PPG is a trade-off between power consumption and accuracy considering the activity type, skin color and skin perfusion. The subject of this thesis is implementing a channel selection algorithm, which is green and IR channel, on a commercially available PulseOn wrist band to optimize the power consumption and accuracy of the measurement. The channel selection algorithm is first implemented and evaluated in Matlab simulation and then implemented in C code. Performance of the channel selection algorithm on the device is evaluated considering various factors, including skin color, tightness of the wristband. The results show that channel selection algorithm can not only reduce the power consumption but also help to handle the measurement on different measurement conditions

Usage and control of solid-state lighting for plant growth

The work begins with an introductory part in which the basic aspects related to the photosynthetic radiation, the photobiology of plants and the technology of light-emitting diodes (LEDs) are overviewed. It is followed by a review of related research works that have been conducted during the last two decades, and by the main design issues of LED luminaires for plant growth. The following part of the work reports the experimental growth tests performed. The effects of the radiation emitted by spectrally tailored LED luminaires on plant growth have been investigated. A total of four growth tests using lettuce and radish cultivars were performed. Two basic approaches were used to investigate the effects and the future possibilities of the usage of solid-state lighting (SSL) in plant growth. The first approach evaluates the growth development of lettuce plants in real greenhouse conditions using LEDs as supplementary light sources to natural daylight. In the second approach the evaluation was carried out with a total absence of natural daylight by growing lettuce and radish plants in phytotron-chamber conditions. The effects of SSL treatments on the growth development and quality of crops were compared with reference lighting systems composed of conventional and well-established light-source technologies, such as fluorescent and high-pressure sodium lamps. During the process of the investigation, the need to coherently quantify and evaluate the spectral quality of the radiation in terms of its photosynthetic appetence arose. Different metrics are still been used indiscriminately to quantify radiation used by plants to perform photosynthesis. Therefore, the existing metrics are discussed and a new proposal for coherent systematization is presented. The proposed system is referred to phyllophotometric and it is developed using the average photosynthetic spectral quantum yield response curve of plants. The results of the growth tests showed that the usage of SSL in plant growth offers an unprecedented possibility to optimise the morphogenesis, the photosynthesis and the nutritional quality of crops. This can be done by controlling the quantity and the spectral composition of the radiation provided, areas where LED-based luminaires excel. These possibilities can contribute to respond to the increasing demand for high-quality horticultural products by the consumers and to the conservation of global natural environment and resources

Thermal management and design optimization for a high power LED work light

This thesis work deals with the optimization project of the heat sink and explains in details the design path of the thermal aspect of a long-life, high quality LED work light, as well as some general fundamentals of product design and manufacturing to consider. Although the path from an idea to the finished product is described mainly from the thermal aspect; the entire process of electronics development and casing mechanical design is not included in this thesis work. The study was done for Five Watts Oy, a company based in Finland designing, developing and manufacturing LED work light solutions for heavy duty equipment. The first prototypes of LED work light were made without proper cooling simulations and thus did not provide sufficient cooling of the LEDs; in a space with no external airflow the prototypes always reached overheat protection temperatures. A proper Computational Fluid Dynamics simulation was made to optimize the most crucial part of the cooling fins, the spacing. The results of the simulation were integrated into overall work light design; nowadays the product is on the market and functioning successfully

Evidence-based strategies for sustainable lighting design in grocery stores

Lighting is arguably the single most important element in retail design. Among retail environments, grocery stores are important for their potential contribution to sustainable community. More than a mundane place for running errands, the grocery store is increasingly a "third place" that sits at the nexus of healthy lifestyles and community gathering. This study explores the ways that lighting helps to enhance these larger goals and advances an approach to lighting design that considers not just the environmental, but also the economic and social impacts of lighting. This study developed two key resources for practitioners involved in the lighting design of grocery stores. The first resource is a sustainable lighting design process and the second product is evidence-based design guidelines for sustainable lighting design in grocery stores. The "sustainable lighting design process" is the result of combining major elements in lighting design with the 3-E framework for sustainability that encourages consideration of environment, economy, and equity. The second resource, and the major undertaking of this thesis, is a systematic review of existing scholarly literature that results in a comprehensive matrix of sustainable lighting guidelines for the grocery store environment. The matrix of guidelines additionally reveals how each guideline relates to the 3 major goals of sustainability. Hence, each study was examined for its contribution to ecological, social, and economic sustainability goals, and sustainability themes were mapped accordingly into the guidelines. The final guidelines can be selected to fit unique applications and contexts by store owners and retail designers. The use of the guidelines, even in part, can improve the sustainability of lighting solutions across numerous dimensions - from reducing the carbon footprint of the building to increasing sales to fostering positive social interactions among customers. These guidelines can also be used by scholars to find gaps in the research field by looking across the matrix and the mapping of sustainability themes. The hope is that future researchers will help to improve the matrix by continuing important research on sustainable lighting strategies