Luminous Intensity Distribution Curves Research Articles

The Impact of Vertical Densification on Public Lighting in Informal Settlements: Using Virtual Environments as an Evaluation Tool for Policy Making

There are a variety of reasons to support the premise that public lighting is beneficial to urban communities. At the same time, a key challenge for the provision of public lighting in informal settlements is their constant physical transformation. The aim of this paper is to evaluate the application of virtual environments (VEs) in lighting planning and policy making. Despite the fact that VEs offer the opportunity to explore an environment by freely navigating through it, including environments that change over time, this feature is rarely taken into account in decision-making processes. A VE-based analysis tool for informal settlement lighting is presented using a case-study street in the informal settlement of Caracolí in Bogotá as its basis. A household survey, spatial measurements, participants’ observations, and luminous intensity distribution curves constituted the main data set for the VE scenarios. Time-related data on the incremental construction of Caracolí’s informal dwellings was collected by the household survey and that data was then projected into past, present, and future night-time scenarios. The lighting quality of these different scenarios was systematically evaluated via lighting calculation software, revealing a variety of shortcomings caused by the current lighting approach. Based on these findings, an alternative lighting approach was developed and re-examined using lighting calculations. Finally, custom game-engine technology and GPU computing were deployed, which allowed for real-time visualisation of the different lighting scenarios and their lighting quality. This setup therefore enables fast iterative feedback loops for current and future lighting policy scenarios and the resulting lighting design. In the first instance, a VE can illustrate well how current lighting policy results in a significant delay of lighting provision in the early stage of a settlement as well as highlighting the mismatch between lighting technology and the built environment during the vertical densification phases. Second, the VE is able to showcase alternative lighting technologies and policy approaches as well as the resulting lighting effects, enabling a visual comparison of different policy scenarios over several decades. In conclusion it will be argued that the dynamic VE technology appears to be a promising decision-making tool for illustrating potential planning and design shortcomings to policy stakeholders in a manner understandable to the layman.

Far-field studies on Eu[formula omitted]-doped lithium aluminoborate glass for LED lighting

The luminous intensity distribution from luminescent glass disks is investigated. For this, the disks are placed on top of an ultraviolet and a blue LED and the emission from the optically-activated glass is recorded in the far field. The luminous intensity distribution of the LED light and the Eu3+ luminescence is considered separately by filtering the LED excitation, the same applies to the measured total luminous flux. Angle-dependent spectra are also measured and the changes in color coordinates are examined versus the viewing angle. The experimental results of the luminous intensity distribution curves are compared with ray-tracing simulations.

Miniature ureteroscope distal tip designs for potential use in thulium fiber laser lithotripsy.

Thulium fiber laser lithotripsy using smaller optical fibers may enable development of miniature ureteroscopes. Two ureteroscope distal tip prototypes were built and characterized. The first design was 4.5-French (Fr) [1.5-mm outer diameter (OD)], five channel tip, housing 200-μm inner diameter (ID) dedicated central channel for insertion of 100-μm core fibers and four surrounding channels, each with 1.5Fr (510-μm ID) for instrumentation, irrigation, imaging, and illumination, respectively. The second design was 6.0-Fr (2.0-mm OD), three-dimensional printed tip with larger, hemispherical common working channel and separate detection port integrated with ring lighting. Standard instruments, including optical fibers, guidewires, and stone baskets, were inserted through working channels to demonstrate feasibility. Gravitational and manual pump-assisted saline irrigation rates were measured. Luminous intensity distribution curves (LIDCs) were modeled for both ring and conventional lighting designs. Imaging was conducted using 3000, 6000, and 10,000pixel, miniature, flexible endoscopes with 0.4-, 0.6-, and 0.9-mm OD, to differentiate between urinary stones and ureter wall, for potential clinical application. The multichannel ureteroscope tip with 1.5-Fr working channel yielded a gravitational saline flow rate of 3.9 ± 0.2 mL / min compared to 31.3 ± 0.6 mL / min for standard (3.6Fr) ureteroscope channel. Manual, pump-assisted irrigation increased flow rate to 32.5 ± 3.0 mL / min. The 6000pixel, 0.6-mm OD, flexible endoscope provided a balance of clear differentiation between stones and ureter wall and sufficiently small OD. A ring lighting configuration provided more uniform illumination than conventional cross-lighting geometry as demonstrated by LIDCs. With further development, these miniature ureteroscope tip designs may be integrated into a fully functional ureteroscope to permit ureteral access with minimal trauma and improved patient safety and comfort.

Features measurement of luminous flux by goniometer

The work covers results of study of influence of goniometer configurations and the environment in which spatial distribution of luminous flux of LED devices measure on the measurement accuracy of the optical characteristics. The article presents methods and means of improving the measurement accuracy of luminous flux. Was performed the analysis of influence of different types of luminous intensity distribution curve (uniform, сosine, spot) of LED devices on the measurement accuracy of luminous flux.

Characteristic matrix operation for finding global solution of one-time ray-tracing optimization method.

The one-time ray-tracing optimization method is a fast way to design LED illumination systems [Opt. Express22, 5357 (2014)10.1364/OE.22.005357]. The method optimizes the performance of LED illumination systems by modifying the LEDs' luminous intensity distribution curve (LIDC) with a freeform lens, instead of modifying the illumination system structure. In finding the LEDs' LIDC for optimizing the illumination system's performance, the LEDs' LIDC found by means of a general gradient descent method can be trapped in a local solution. This study develops a matrix operation method to directly find the global solution of the LEDs' LIDC for the optimization of the illumination system's performance for any initial design of an illumination system structure. As compared with the gradient descent method, using the proposed characteristic matrix operation method to find the best LEDs' LIDC reduces the cost in time by several orders of magnitude. The proposed characteristic matrix operation method ensures that the one-time ray-tracing optimization method is an efficient and reliable method for designing LED illumination systems.

Design and Analysis of an Underwater White LED Fish-Attracting Lamp and its Light Propagation

Light emitting diodes (LED) are a new source for replacing traditional light sources including under water illumination. As traditional underwater light sources operate under a radiative transfer model, the luminous intensity is dispersed evenly at each emission angle, with the scattering factors included in the attenuation coefficient. By contrast, LED light sources are characterized by being highly directional, causing underwater luminous energy to vary with different emission angles. Thus, the traditional theory of underwater optical transfer becomes inapplicable when an underwater LED lighting module is designed. Therefore, to construct an underwater transfer model for LED light sources, this study employed the average cosine of the underwater light field, the method for light scattering probability, the LED luminous intensity distribution curve (LIDC) and axial luminous intensity. Afterwards, an underwater LED fish-attracting lamp was designed. Experimental results showed that, compared with the simulation values, the luminous intensity of the underwater LED lighting module at all emission angles had a percentage error of less than 10%.

A Basic Study on the Prediction of Luminous Intensity Distribution Curves of the Light Source Using the Floor Illuminance Distribution in a Room

We have already published several papers describing application of an approximate calculation method for calculating interreflection in a room with fixtures. As a result, it is clarified that the illuminance ratio (illuminance ratio =the floor illuminance in a room with fixtures / the floor illuminance in a room where fixtures do not exist) distribution on the floor does not depend to the luminous intensity distribution curves of the light source. The method is presented for predicting the floor illuminance in a room (we called this the real space) with fixtures and a non-uniform diffuse light source from the floor illuminance in a room (we called this the virtual space) with no fixtures. In the previous paper, we presented that the luminous intensity distribution curves of light source of the narrow angle type and wide angle type can be represented as a polynomial expression with the components of cosine to the kth power and angle ακ of maximum luminous intensity. This paper proposed a method for predicting luminous intensity distribution curves of the light source when desired floor illuminance distributions is given. (we called this the inverse problem) This inverse problem of lighting design is useful for designing practical rooms, and ito procedures are as follows. First, the floor illuminance distribution of real space is replaced with floor illuminance distribution of virtual pace. Next, the relationship between position of the floor and floor illuminance distribution in a virtual room is expressed by the sixth equation. Finally, the relationship between the coefficient of the sixth polynomical with degree κ and the angle ακ of maximum luminous intensity of the light source is discussed. As a result, it is clarified that the luminous intensity distribution curves of the light source could be predicted from the coefficient of the equation, which has relation to floor illuminance distribution.

Luminous intensity distribution curves: Classification proposals

A method for classification luminous intensity distribution curves with fixed tolerance zones for luminous intensity values is developed. The method defines the luminous intensity distribution not ...

Computer Aided Design Method to Predict the Luminous Intencity Distribution of Reflector Part 2

In the previous paper, the author described the computer-aided design method to predict the luminous intensity distribution curves of simple reflectors.In this paper, CAD method on revolved parabolic reflectors with a high intensity discharge lamp is described in the development of the theory in Part 1.Quantities of the direct light and reflected light on the surfaces of the reflector are computed at various vertical angles, then two computed values are summed up to decide the luminous intensity.Most efforts are directed towards formulation of a computer program to calculate the intensity from reflected light component.The light emitteing surface of the lamp is dievided into many parts, light rays from each part are traced exactly in accordance with the reflection in properties of the reflector's finish.Then, shape of the reflector is designed such that as littl reflected light as possible may fall on to the lamp.In the application of this CAD method, sufficient results are obtained practically from many experimental measurements.Thus, new high efficiency reflectors have been developed by this method.