Randomized trial of polychromatic blue-enriched light for circadian phase shifting, melatonin suppression, and alerting responses.

Wavelength comparisons have indicated that circadian phase-shifting and enhancement of subjective and EEG-correlates of alertness have a higher sensitivity to short wavelength visible light. The aim of the current study was to test whether polychromatic light enriched in the blue portion of the spectrum (17,000 K) has increased efficacy for melatonin suppression, circadian phase-shifting, and alertness as compared to an equal photon density exposure to a standard white polychromatic light (4000 K). Twenty healthy participants were studied in a time-free environment for 7 days. The protocol included two baseline days followed by a 26-h constant routine (CR1) to assess initial circadian phase. Following CR1, participants were exposed to a full-field fluorescent light (1 × 10 14 photons/cm 2 /s, 4000 K or 17,000 K, n = 10/condition) for 6.5 h during the biological night. Following an 8 h recovery sleep, a second 30-h CR was performed. Melatonin suppression was assessed from the difference during the light exposure and the corresponding clock time 24 h earlier during CR1. Phase-shifts were calculated from the clock time difference in dim light melatonin onset time (DLMO) between CR1 and CR2. Blue-enriched light caused significantly greater suppression of melatonin than standard light ((mean ± SD) 70.9 ± 19.6% and 42.8 ± 29.1%, respectively, p \u3c 0.05). There was no significant difference in the magnitude of phase delay shifts. Blue-enriched light significantly improved subjective alertness (p \u3c 0.05) but no differences were found for objective alertness. These data contribute to the optimization of the short wavelength-enriched spectra and intensities needed for circadian, neuroendocrine and neurobehavioral regulation

Development of a CAN Based Electric Vehicle Control System

Abstract The Intelligent Systems and Automation Lab (ISAL) at the University of Kansas has been working on developing new electric vehicle drivetrain and battery technology using an electric bus as a development platform. In its preexisting state the bus featured an unreliable control system to manage load control and drive enable functions. As a result this thesis presents the design of a Controller Area Network (CAN) based control system to be used as a replacement for the existing system. The use of this new system will allow for easy expansion, higher efficiency and greater reliability in further developing the ISAL electric bus concept vehicle. Controller Area Network protocol allows the system to easily implement smart features allowing multiple modules to work together as well as reduce the overall wiring complexity of the control system. CAN networks utilize a single twisted pair cable and differential transmission to reliably transmit data to all modules featured in the control system. Additionally, because CAN is a common network protocol used in automotive electronics it will be easy to interface with other existing automotive electronics. This thesis shows the development of six different CAN modules as well as a proposed implementation for the complete system. Developed modules include an Interior Lighting Module, Headlights and Accessories Load Module, Accelerator Pedal Sensor Module, Battery Voltage Sensor Module, Input Module, and Speed Sensor and Display Module. Modules serve the purpose of reading sensors, controlling electric loads and displaying pertinent information to the driver. A prototype of this system featuring one of each module has been created for display and test purposes and is fully functional

Commercialisation of precision agriculture technologies in the macadamia industry

A prototype vision-based yield monitor has been developed for the macadamia industry. The system estimates yield for individual trees by detecting nuts and their harvested location. The technology was developed by the National Centre for Engineering in Agriculture, University of Southern Queensland for the purpose of reducing labour and costs in varietal assessment trials where yield for individual trees are required to be measured to indicate tree performance. The project was commissioned by Horticulture Australia Limited

A high resolution full-field range imaging system for robotic devices

There has been considerable effort by many researchers to develop a high resolution full-field range imaging system. Traditionally these systems rely on a homodyne technique that modulates the illumination source and shutter speed at some high frequency. These systems tend to suffer from the need to be calibrated to account for changing ambient light conditions and generally cannot provide better than single centimeter range resolution, and even then over a range of only a few meters. We present a system, tested to proof-of-concept stage that is being developed for use on a range of mobile robots. The system has the potential for real-time, sub millimeter range resolution, with minimal power and space requirements

LUMINANCE DESIGN A SIMULATION USING COLOUR TELEVISION

A successful lighting design usually results from the skill of the designer in applying professional experience. However, successful designs have been achieved using numerical prediction. It is probable that a blend of both these elements will give the optimum result. Whatever the design approach, the end product will be judged, at least in part, on its aesthetic merits. The first chapter of this thesis introduces the possibility of using a digital computer in conjunction with a colour television monitor to calculate and display the luminance distribution in a lighted room; a system which may offer advantages both for the experienced designer and the student of lighting design. The display system is described briefly, along with some possible shortcomings. An account is given of the methods used for inter-reflection calculation. These inter-reflection calculations are then developed to include colour and techniques of photometric and colorimetric measurement with reference to the television display. A complete description of the display system hardware is also given. This display system as initially designed uses chromaticity as the criterion for colour reproduction. The shortcomings of this approach are discussed. Techniques for perceived colour measurement are described and the results presented for the colour perceived from some simple display images. The possibility of perceived colour prediction is examined and measured colours are compared with those predicted by a non-linear model. Finally, the applications of the display are discussed, both in an educational and design context. Some possible developments and improvements are also outlined

Optimization of the light dynamics in the Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR)

The research objective was the optimization of light dynamics in a Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR). A deterministic model of HISTAR productivity that was responsive to manipulations of photosynthetic photon flux fluence rate (PPFFR) was developed, calibrated, and applied. A series of experiments was conducted to define the mathematical equations that best describe three relationships. The first relationship was between the elevation (E) of the light source and the culture surface PPFFR (Io). The second relationship was between the biomass concentration (X) in the experimental unit and the average PPFFR in the reactor (Ia). The final relationship was between average PPFFR and the net specific growth rate (U). Parameters for these three relationships varied for light sources having different spectra. The light source specific parameters investigated were the light attenuation coefficient (kaw), maximum specific growth rate (μmax) and optimum average PPFFR (Iopt). These parameters were estimated experimentally (using Selenastrum capricornutum as the surrogate microalgal species) for metal halide, high-pressure-sodium (HPS), fluorescent, and Son Agro® lights. Using the experimentally estimated parameters for metal halide and the three experimentally defined relationships, a HISTAR productivity model was developed using the Stella® modeling platform and calibrated using actual HISTAR data. Biorhythms were discovered in the residuals during a calibration attempt. These harmonics were modeled and incorporated into the productivity model before completing calibration. The HISTAR productivity model was then used to simulate the effects of light source type, system dilution rate (Ds), number of CFSTRs, wattage, lamp elevations, and culture depth on daily productivity in HISTAR. It was concluded from simulation studies that using HPS lamps, a Ds of 0.641 d-1, changing lamp elevations to 25.4 cm, and changing culture depth in the last four CFSTRs of HISTAR would be cost beneficial. The production lighting cost (LC, based on $0.10 killowatthour-1) may be reduced from$48 (kg dry wt)-1 to $36 (kg dry wt)-1. Decreasing the number of CFSTRs in HISTAR or increasing lamp wattage was not predicted to be cost effective. The outcome of this type of research for other species adapted to different habitats would probably differ

A framework for predicting the non-visual effects of daylight - part I: photobiology-based model

This paper investigates the formulation of a modelling framework for the nonvisual effects of daylight, such as entrainment of the circadian system and maintenance of alertness. The body of empirical data from photobiology studies is now sufficient to start developing preliminary non-visual lighting evaluation methods for lighting design. Eventually, these non-visual effects have the potential to become a relevant quantity to consider when assessing the overall daylighting performance of a space. This paper describes the assumptions and general approach that were developed to propose a modeling framework for occupant exposure to non-visual effects of light, and presents a novel means of visualising the ‘circadian potential’ of a point in space. The proposed approach uses current outcomes of photobiology research to define – at this point static – threshold values for illumination in terms of spectrum, intensity and timing of light at the human eye. These values are then translated into goals for lighting simulation, based on vertical illuminance at the eye, that – ultimately – could become goals for building design. A new climate-based simulation model has been developed to apply these concepts to a residential environment. This will be described in Part 2 of this paper