Unlike more general structures, a tunnel is a space that has district particularities such as the need for lighting even in the daytime. It is necessary to install appropriate lighting equipment, especially efficient lighting equipment, in tunnels. Light distribution of luminaire is a factor that affects the equipment scale. However, the relationship between light distribution and energy consumption has not yet been clarified. Against this backdrop, we propose a light distribution design method for highly efficient tunnel lighting that reduces energy consumption and a tunnel lighting design method that optimizes the features while fulfilling lighting performance requirements based on the relationship between the light distribution of tunnel lighting and the illumination characteristics for tunnel luminance (symmetrical lighting method) used as existing tunnel luminance. We evaluated the effects of luminance on the light distribution by simulations in an actual tunnel and confirmed the effectiveness of the energy saving.
The optimum specifications of an LED operation circuit based on a Cockcroft-Walton circuit were investigated. It was found that the four-times-circuit with an LED operating voltage set to about 50 % of the non-load output voltage is preferable, since the number of elements in the circuit and the capacitance of each capacitor could be minimized. Then, the cost of the LED operation circuit could be minimized by using a four-times-circuit. The input power factor is maximum when the LED operating voltage was set to about 80 % of the non-load output voltage, and the maximum value of the input power factor increases with increasing step-up voltage of the circuit. It was also found that the eight-times-circuit could satisfy the harmonics regulation regarding the input current of electronic equipment by adjusting the LED operation voltage and capacitance ratio.
Exterior illumination in populated areas is part of the basic infrastructure used to secure relief from darkness and to ensure safety for social and economic activity at night. However, it can also be a source of light pollution. In wet rice cultivation, light pollution due to exterior illumination results in delayed flowering (heading), which in turn leads to a reduced yield and to a low-inspection grade at the harvest stage. Therefore, the relationship between a delayed heading period and the light intensity or irradiation period needs to be studied. This study attempts to models the rice growth process in light pollution to propose lighting and cultivation management that will ensure pedestrian safety as much as possible while utilizing countermeasures against light pollution at effective and appropriate times.