Multiple Lamps Research Articles

Improvement of temporal light artefact effects in commercial LED lamps

Temporal light modulation and its potential adverse visual effects on human observers, collectively known as temporal light artefacts (TLAs), have been limited by the European Union Ecodesign regulation. Limitations on two key TLA metrics, flicker and stroboscopic effect, were introduced in September 2021. This study analyses the impact of this regulation on commercial LED lamps by measuring multiple different consumer-grade LED E27 retrofit lamps by several manufacturers before and after the regulation. The lamps purchased after the Ecodesign regulation seem to favour a certain type of LED driver that provides the best TLA behaviour of all lamp types. The regulation, with respect to TLA, has resulted in the replacement of ill-behaving lamp types in the market by newer lamps with better TLA characteristics.

Optimal location design for multiple Far-UVC lamps to enhance indoor bioaerosol disinfection by CFD-based Bayesian optimization

In occupied indoor environments, 222 nm far-UVC is a secure and effective approach for controlling the spread of infectious bioaerosols. To enhance the disinfection effectiveness, it is crucial to carefully design the placement of far-UVC lamps, by considering the impact of airflow pattern, bioaerosol distribution, and irradiance exposure. Using CFD alone for designing the locations of multiple lamps presents challenges due to the high computational cost resulting from the high number of potential combinations. Therefore, this study combined CFD with the Bayesian optimization method to improve the computational efficiency, enabling customized design for complex scenarios. The proposed method was first validated with experimental data and the results from the grid search method. Next, the validated method was applied to design the placement of multiple far-UVC lamps in a railway compartment. In the studied railway compartment, just 1 h of optimization led to 1.05-fold–2.87-fold improvement in bioaerosol disinfection efficiency compared to random selection and uniform distribution. This optimization method for customized location design can maximize the utilization of far-UVC lamps, reducing equipment investment and energy consumption while ensuring effective disinfection.

A new airfield lighting system network architecture

Airport navigation lights are essential for safe night and adverse weatherflying. Airfield ground lighting (AGL) systems providevisual guidanceduring airport operations. These systems use multiple lamps connected inseries with constant current regulators (CCRs) to provide power. Promptdetection and location of failed lamps are critical to airport efficiency andcost savings. Local area network (LAN) communication facilitates lampmonitoring and control, improving system performance and reducingmaintenance costs. Effective transmission media are critical for systemreliability and efficiency. This article presents a new network architecturefor AGL systems that connects lamps and the control system using a newintelligent module; this architecture combines star and bus topologies in ahybrid intranet network. The obtained results show excellent networkingperformances by means oflatency and throughput. This architectureimproves operational efficiency and reduces maintenance for AGL systems.

Measuring the performance of conventional and emerging ultraviolet-C light sources for bacterial, fungal, and mycotoxin control

The performance of two conventional monochromatic ultraviolet-C (UV-C) low pressure mercury (LPM) sources (single and multiple lamps) was measured and compared with three emerging UV sources: a monochromatic KrCl* excimer lamp and UV-LEDs, and a polychromatic pulsed light (UV-C PL) lamp. Fluence-based kinetic parameters and electrical energy per order (EE0) of the UV sources was determined for the inactivation of E. coli bacteria, the reduction of deoxynivalenol (DON) mycotoxin, and F. graminearum spore growth to assess feasibility for various processing targets. The impact on E. coli photoreactivation and dark repair was also assessed. Each of the five UV sources excelled in certain applications while not being feasible for others. The UV-C PL lamp was the most effective for E. coli inactivation, requiring the lowest fluence of 1.4 mJ/cm2 for 5-log10 reduction. The KrCl* excimer lamp was the most effective for preventing subsequent photoreactivation. The UV-LEDs and LPM lamp were equally effective for reducing fungal spore growth requiring 77.0 and 90.1 mJ/cm2 to achieve 90% reduction, respectively. The KrCl* excimer and UV-C PL lamps were the most effective at reducing DON contamination requiring 1250 and 500 mJ/cm2 to achieve 90% reduction, respectively. The evaluation of EE0 showed that the conventional LPM source with multiple lamps had approximately 2–3-fold better electrical efficiency for the reduction of all three tested targets due to its high wall plug efficiency compared to the next best UV-C PL lamp. This indicates that energy efficiency of emerging UV sources needs to be improved in further development.

Design, fabrication, and evaluation of a large-area hybrid solar simulator for remote sensing applications.

Solar irradiance variations have a direct effect on the accuracy and repeatability of identifying spectral signatures in the remote sensing field experiments. Solar simulators have been deployed to allow for testing under controlled and reproducible laboratory conditions. However, it is difficult and expensive to make a large-area solar simulation with the appropriate spectral content and spatial uniformity of irradiance. In this study, a hybrid solar simulator has been designed and constructed to provide large-area illumination for remote sensing simulation applications. A design method based on the two-phase genetic algorithm is proposed to improve the performance of the spectral match and spatial uniformity, which no longer relies on the traditional trial-and-error technique. The first phase is used to determine the most appropriate configuration of different lamps in order to represent the solar spectrum. The second phase is to accommodate an optimal placement of the multiple sources to achieve irradiance uniformity. Both numerical simulations and experiments were performed to verify the performances. The results showed that the solar simulator provided a good spectral match and spatial irradiance for simulating the variations in direct normal irradiance at different solar zenith angles. In addition, the modular design makes it possible to adjust irradiance on the target area without altering the spectral distribution. This work demonstrates the development and measurement of a hybrid solar simulator with a realizable optimal configuration of multiple lamps, and offers the prospect of a scalable, large-area solar simulation.

An Appropriate Index to Assess the Global Cancellation Level of the Harmonic Currents Consumed by a Set of Single-Phase Uncontrolled Rectifiers and a Set of Fluorescent Lamps

An in-depth study of harmonic current reduction in European commercial buildings due to the harmonic cancellation effect when a set of single-phase uncontrolled rectifiers and a set of fluorescent lamps are connected at the same voltage level is essential, since both types of non-linear loads are very present in commercial and residential sectors. This paper provides an appropriate index to assess the global cancellation level of the harmonic currents for this study. The equivalent circuit per phase of the typical three-phase power system of European commercial installations is presented and simplified for the cancellation analysis of the harmonic currents consumed by a set of multiple identical single-phase uncontrolled rectifiers and a set of multiple identical fluorescent lamps connected at the same voltage level. The suitability and usefulness of the proposed index are shown by applying it to that analysis, which leads to some results of practical interest. This index can be generalized to any number of sets of multiple identical non-linear loads and can be applied in graphical and optimization studies that will allow a greater benefit from the harmonic cancellation effect to be obtained given the global nature of the index.

Application Research of Portable On-line Inspection System for Car Lights

In this article, a portable automotive lighting online detection system is designed, which can test various signals of car lamps online. It also can perform function and performance tests on multiple car lamps at the same time. The system has a compact structure in order to be easy to carry. It can be tested in the car light laboratory or be used for on-line testing of the production line. The system can automatically complete data collection and processing online. It can discriminate test results and print test reports easily. It has strong versatility and high measurement accuracy. This portable online detection system is convenient for detection and has good application value.

Assessment of Conducted Emission for Multiple Compact Fluorescent Lamps in Various Grid Topology

This paper presents the measurement of aggregated conducted emission in the frequency range of 9 kHz to 150 kHz produced by multiple compact fluorescent lamps (CFL) and how it equates to a multiple power converter system. Discrepancies in peak emission measurement results related to this application are illustrated to understand the underlying issue related to volatility of frequency components. Furthermore, this knowledge analyzes the relation of electromagnetic disturbances with respect to different topological network connections. The final presented results constitute theoretical description and statistical information about the characteristics of conducted emission measured in this multi-converter system.

Computational fluid dynamics modelling of quasi-collimated beam apparatus - a typical bench scale UV apparatus for water treatment.

Quasi-collimated beam apparatus (QCBA), a typical bench scale UV apparatus, is crucial for the biodosimetry determination of UV dose in target reactors. However, the key parameters for the QCBA construction are usually estimated via rule-of-thumb calculations. Computational fluid dynamics models are applied in this study to simulate the UV fluence rate (FR) distributions in QCBAs. QCBAs with either a cylindrical tube or successive apertures irradiate quasi parallel light into selected dishes. The simulated Petri factors (PF) in the target QCBAs with a single aperture were all >0.84, and increased with the extended distance (L1) from the UV lamp to the upper aperture. QCBAs with two successive apertures are recommended compared with those with three apertures or cylindrical tube. A trend of FR distribution from dispersed to concentrated is observed when L1 or the interval distance between each aperture increases in a dual-aperture QCBA. QCBAs with multiple lamps were favorable to increase the UV output power, while having a nearly negligible loss of parallelism. An actual QCBA was constructed, and the maximal and average FR and PF values in a 60-mm dish were 0.159 and 0.164 W/m2, and 0.967, respectively, in accordance with the simulated results.

Indoor MIMO VLC systems using optical orthogonal frequency division multiple access

This paper proposes an indoor multiuser visible light communication (VLC) system using multiple lamps with orthogonal frequency division multiple access (OFDMA) techniques. For the users located in different places, the diversities of their channels help to optimally allocate the subcarriers to the users for high-speed transmissions. Considering the peak radiation power limited light sources, the modulation index on each subcarrier is jointly optimized with the subcarriers assignment scheme. This paper proposes a genetic algorithm and a two-stage searching method to solve this joint optimization problem. Considering the computational complexity, a distributed optimization scheme together with the resource block methods are applied. From simulation results, the distributed optimization method significantly reduces the computational complexity and only sacrifices about a 30% data rate. This paper takes the illumination requirements into account. By changing the additive DC bias, the average optical power is adjusted; then, the throughput performances over different illumination levels are discussed. Due to the channel feedback error, the channel uncertainty is modeled and considered in this paper. Based on the simulation results, knowing the channel uncertainty can provide around 6 times higher bit rate than not knowing the uncertainty when the normalized variance of channel uncertainty is −3 dB.

A 130 kWe solar simulator with tunable ultra-high flux and characterization using direct multiple lamps mapping

The indoor solar simulator is an excellent supply device for high solar flux applications, but usually suffers from the low flux under a large light area and unadjustable light distribution. In this work, a 130 kWe indoor solar simulator with tunable ultra-high flux in a projection area of 200 mm diameter is designed and established. 13 of 10 kWe xenon short-arc lamps and reflectors are coupled to make the flux be concentrated to a spot. Besides, a direct measure system consisting of a Gardon gauge and a two-dimensional moving unit is proposed to map the flux distribution. The expanded uncertainty is 7.46% with a converge factor of 2, compared with the conventional indirect camera-based method with an error up to 50%. Up to 7 lamps are simultaneously measured. The Monte Carlo method is adopted to analyze flux distributions of individual lamps as well as the whole lamp group, which coincides well with the experimental data. When the input electric power is 11.12 kW, the electric-to-light conversion efficiency is 31.60% ± 2.36% on the focus plane. The peak flux reaches 11.267 ± 1.571 MW/m2 and a mean flux amounts to 1.054 ± 0.079 MW/m2 in a projection area of 200 mm diameter. Both the distribution and non-uniformity of irradiation flux are tunable. By reducing the power of the central lamp to the half and defocusing the target, the distribution non-uniformity of the light intensity can be remarkably reduced from 68.87% to 18.59% in a projection area of 60 mm diameter. The developed device will provide a reliable source for indoor experiments.

Indoor multiuser visible light communication systems using Hadamard-coded modulation.

Visible light communications (VLC) is a short-range optical wireless communication technology that uses light-emitting diodes (LEDs) as lighting devices and data transmitters. This paper describes a multiuser VLC system using Hadamard-coded modulation (HCM) for indoor data transmission. Considering the peak transmitted power limit of the LEDs, a DC-reduced HCM (DCR-HCM) is used to reduce the nonlinear clipping distortion. Since the Hadamard codewords have different bandwidth requirements for a given symbol rate, they can be assigned to users with varying hardware capabilities. Optimally assigning codewords to users is found to significantly improve the average throughput, up to twice higher than a random assignment for a typical scenario. When the number of active users is less than the size of the Hadamard matrix used, more than one codeword can be assigned per user, which further improves the throughput. This paper also examines a scenario where multiple lamps in an indoor space transmit the same data. Since the time of arrival for the received signals emitted from different lamps is different, the Hadamard codes received are no longer orthogonal, resulting in multiple access interference and inter-chip interference. The number of acceptable codewords is computed based on the specific interference experienced in different parts of the indoor space. The spatial distribution of the maximum throughput is also simulated, showing that the ratio of the maximum to the minimum data rate can be as high as 10 when considering the entire area of a typical indoor room.This article is part of the theme issue ‘Optical wireless communication’.

In Situ Measurement of Carbon Nanotube Growth Kinetics in a Rapid Thermal Chemical Vapor Deposition Reactor With Multizone Infrared Heating

Abstract Understanding and controlling the growth of vertically aligned carbon nanotube (VACNT) forests by chemical vapor deposition (CVD) is essential for unlocking their potential as candidate materials for next generation energy and mass transport devices. These advances in CNT manufacturing require developing in situ characterization techniques capable of interrogating how CNTs grow, interact, and self-assemble. Here we present a technique for real-time monitoring of VACNT forest height kinetics applied to a unique custom designed rapid thermal processing (RTP) reactor for CVD of VACNTs. While the integration of multiple infrared heating lamps enables creating designed spatiotemporal temperature profiles inside the reactor, they pose challenges for in situ measurements. Hence, our approach relies on contrast-adjusted videography and image processing, combined with calibration using 3D optical microscopy with large depth-of-field. Our work enables reliably measuring VACNT growth rates and catalytic lifetimes, which are not possible to measure using ex situ methods.

3-D Localization With Multiple LEDs Lamps in OFDM-VLC System

Visible light communication (VLC)-based localization is a potential candidate for a wide range of indoor localization applications. In this paper, we propose a VLC architecture based on orthogonal frequency division multiplexing (OFDM) with multiple functionalities integrated into the same system, i.e., the 3-D receiver location, the control of the room illumination intensity, as well as the data transmission capability. In this paper, we propose an original methodology for LED power discrimination applying spatial optical OFDM (SO-OFDM) structure for position estimation. The hybrid locator initially makes a first estimate using a weighted angle-of-arrival (WAoA)-based locator, which is then used as the starting point of the recursive estimator based on the strength of the received signal. Hence, the first stage is deployed to increase the convergence probability, reducing the root-mean-square error (RMSE) and the number of iterations of the second stage. Also, a performance versus computational complexity comparative analysis is carried out with the parameter variations of these estimators. The numerical results indicate a decade improvement in the RMSE for every two decades of decrement of power noise on the receiver photodiode. The best clipping factor is obtained through the analysis of locator accuracy and transmission capacity for each simulated system. Finally, the numerical results also demonstrate effectiveness, robustness, and efficiency of the proposed architecture.

Ritual Sites and Religious Rivalries in Late Roman North Africa by Shira Lander

[...]Lander uses the archaeological record to read against the grain of the literary one, thereby flouting scholarly conventions that prioritize textual evidence. [...]she identifies the rhetorical spatial strategies that Nicene Christians (Catholics) deployed to distance themselves from other sects, whom they variously cast as Donatists, Novatianists, and Jews. [...]given the popularity of graffiti in marketplaces and theaters in the Roman East, which constitute forms of religious competition, one wonders whether comparable attention to data from African civic spaces might enhance this regional study (Angelos Chaniotis, Memory, Commemoration and Identity in an Ancient City: The Case of Aphrodisias, Daedalus 145.2 [2016]: 88–100). Published excavation reports from the Naro synagogue (Hammam Lif) record discoveries of multiple lamps, suggesting some historical Christian presence (or potential displacement, or reuse?) at that site (Karen B. Stern, Inscribing Devotion and Death: Archaeological Evidence for Jewish Populations in North Africa [Leiden: Brill, 2007], 245–47).

Interface-Free Area-Scalable Self-Powered Electroluminescent System Driven by Triboelectric Generator.

Self-powered system that is interface-free is greatly desired for area-scalable application. Here we report a self-powered electroluminescent system that consists of a triboelectric generator (TEG) and a thin-film electroluminescent (TFEL) lamp. The TEG provides high-voltage alternating electric output, which fits in well with the needs of the TFEL lamp. Induced charges pumped onto the lamp by the TEG generate an electric field that is sufficient to excite luminescence without an electrical interface circuit. Through rational serial connection of multiple TFEL lamps, effective and area-scalable luminescence is realized. It is demonstrated that multiple types of TEGs are applicable to the self-powered system, indicating that the system can make use of diverse mechanical sources and thus has potentially broad applications in illumination, display, entertainment, indication, surveillance and many others.

Automatic Lighting System Using Multiple Robotic Lamps

An automatic lighting system using 3-DOF robotic lamps and a laser scanner is proposed in this paper. The 3-DOF robotic lamp, which is designed with a spherical parallel mechanism with a unique forward kinematic solution, has a tilting motion to track a person and zoom-in and zoom-out motions to control the light intensity. In order to minimize the dynamic load, three actuators are installed at the base frame, and a counterbalancing design is considered. The positions of people are detected by a laser scanner, and the Kalman filter and a data association algorithm are applied in order to track the positions of people accurately. Therefore, multiple robotic lamps can track and illuminate each person continuously. We demonstrate experimentally that three robotic lamps mounted on the ceiling illuminate three people independently and control the intensity of the light according to the distance between a person and the robotic lamp.

CFD simulation of a pilot scale slurry photocatalytic reactor and design of multiple-lamp reactors

The hydrodynamics behaviour and radiation transport occurring inside a pilot-scale slurry photocatalytic reactor (treating real shower water) with large diameter was investigated using computational fluid dynamics (CFD). The multiphase flow system was solved using a granular Eulerian model while the solution of the radiative transport equation (RTE) was solved using the finite volume based discrete ordinate model (DOM). Multiphase simulation showed recirculation zones caused by the high slurry inlet velocity. Due to the rapid attenuation of light occurring radially within the reactor, regions of varying reaction orders exist, i.e., half order reaction close to the lamp and first order reaction further from the lamp, as the incident radiation goes below a certain value. A rate equation relating pollutant degradation to the rate occurring in the half and first order reaction regions (in terms of local volumetric rate of energy absorption – LVREA) was proposed. Using a value of 225Wm−2 as the minimum incident light intensity at which half order reactions take place, a Pearson correlation of 0.88 between simulated and experimental data indicated that the proposed model satisfactorily described the experimental observations. Next, simulations performed with a system of multiple lamps (2 and 4 lamps) at different geometrical arrangements (i.e. with the lamps separated by the distance Xlamp) showed that within the range of catalyst concentration investigated, the maximum potential increases in reaction rate was 56% and 123% when using 2 and 4 lamps (at optimum lamp arrangement) respectively, as compared to using one lamp. The increase in reaction rate occurred due to the maximisation of incident radiation contours at which first order reactions take place. The optimum lamp separation was dependent on the catalyst concentration in the wastewater and decreased with increasing catalyst concentration.

Adjustable Multi-Light Wireless Remote Control System Designed LED Light

With the development of LED technology, the actual demand of the people for the smart home lighting, this paper designed a multiple lamps for indoor wireless remote control dimmable LED lighting systems. LED driver is using two levels of drive structure, and driver power supply adopts double-road current output, and the size of the output current of each constant current source is flexible to adjust by remote control. Wireless remote control part control multiple lamps by using 4 * 4 keyboard, which realizes intelligent management of LED interior lighting in the smart home.

Indoor location awareness based on received signal strength ratio and time division multiplexing using light-emitting diode light

We propose and demonstrate an indoor location awareness method for an autonomous robot vehicle using light-emitting diodes (LEDs). The location is estimated by measuring received signal strength ratio (RSSR), which is the relative ratio of optical powers detected between each LED and optical receiver. In this method, multiple LED lamps on the indoor ceiling are used, which can radiate light only during the individual time slot assigned to each of them. Using the RSSRs, circle or straight line equations are obtained and the crossing point among those equations determines the location of the object. In the experiment, four LED lamps are iden- tified by time-division multiplexing with room dimensions of 1.0 × 1.0 × 1.3 m 3 , and the results show that the mean of the location error is 3.24 cm in the entire floor area. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including