Factors influencing the changing patterns of field windbreaks in southwestern Kansas

Call number: LD2668 .T4 GEOG 1988 D54Master of ArtsGeograph

Lead-Free Perovskite-Inspired Absorbers for Indoor Photovoltaics

With the exponential rise in the market value and number of devices part of the Internet of Things (IoT), the demand for indoor photovoltaics (IPV) to power autonomous devices is predicted to rapidly increase. Lead-free perov skite-inspired materials (PIMs) have recently attracted significant attention in photovoltaics research, due to the similarity of their electronic structure to high-performance lead-halide perovskites, but without the same toxicity limitations. However, the capability of PIMs for indoor light harvesting has not yet been considered. Herein, two exemplar PIMs, BiOI and CsSbClxI-x are examined. It is shown that while their bandgaps are too wide for single-junction solar cells, they are close to the optimum for indoor light harvesting. As a result, while BiOI and CsSbClxI-x devices are only circa %-ecient under -sun illumination, their eciencies increase to –% under indoor illumination. These eciencies are within the range of reported values for hydrogenated amorphous silicon, i.e., the industry standard for IPV. It is demonstrated that such performance levels are already sucient for millimeter-scale PIM devices to power thin-film-transistor circuits. Intensity-dependent and optical loss analyses show that future improvements in eciency are possible. Furthermore, calculations of the optically limited eciency of these and other low-toxicity PIMs reveal their considerable potential for IPV, thus encouraging future eorts for their exploration for powering IoT devic

An evaluation of the lighting environment in the public space of shopping centres

Interior lighting quality influences people's visual comfort and satisfaction with a space. Based on a field study about the effects of lighting environments on occupancies in eight shopping malls with three different latitudes and a wide range of size from 30,000 to 210,000 m2 all over China, this study investigates the differences in subjective evaluations, the correlations between the lighting environments of public spaces and people's evaluations, and the regressions of scene mean luminance. A questionnaire survey and HDR-image techniques have been used to gather subjective feedback and collect physical lighting data. The results show that the subjective evaluations among different groups (gender, age, education background, and duration of stay in the shopping malls) are similar. The existence of daylighting plays an important role in subjective satisfaction, but not crucial enough to their brightness perception. The mean luminance values of these scenes are closely correlated to the diversity of the subjective evaluations. For shopping centres, the optimal Lmean value is 1000 cd/m2 for a mixed daylighting and artificial lighting environment, and 75 cd/m2 as the recommended Lmean value for an artificial lighting environment

Power analysis, sample size, and assessment of statistical assumptions—improving the evidential value of lighting research

The reporting of accurate and appropriate conclusions is an essential aspect of scientific research, and failure in this endeavor can threaten the progress of cumulative knowledge. This is highlighted by the current reproducibility crisis, and this crisis disproportionately affects fields that use behavioral research methods, as in much lighting research. A sample of general and topic-specific lighting research papers was reviewed for information about sample sizes and statistical reporting. This highlighted that lighting research is generally underpowered and, given median sample sizes, is unlikely to be able to reveal small effects. Lighting research most commonly uses parametric statistical tests, but assessment of test assumptions is rarely carried out. This risks the inappropriate use of statistical tests, potentially leading to type I and type II errors. Lighting research papers also rarely report measures of effect size, and this can hamper cumulative science and power analyses required to determine appropriate sample sizes for future research studies. Addressing the issues raised in this article related to sample sizes, statistical test assumptions, and reporting of effect sizes can improve the evidential value of lighting research