Algorithm for real-time colour mixing of a five-channel LED system while optimising spectral quality parameters

Multichannel LED luminaires with more than three channels offer the advantage to vary the spectrum and keeping the chromaticity steady. However, the optimisation calculations of various quality metrics are a challenge for real-time implementation, especially for the limited resources of a luminaire’s microcontroller. Here, we present a method in which a five-channel system is simulated with a quickly solvable 3-channel system by defining virtual channels, each consisting of two LED channels. An analysis of the influence of the parameterisation of the virtual valences on various quality metrics is presented. It shows how these parameters must be set at the time of the mixing calculation, in order to optimise the desired quality aspect. The mixing calculation can thus be carried out in real-time without high hardware requirements and is suitable for further developments, for example, to compensate for colour drift of the LEDs through sensor feedback.

A Spectral Spectacle

After Amsterdam’s late medieval Catholic monasteries were surrendered to the Protestant government in 1578, four of these properties were converted into an orphanage, mental asylum, and gender-specific reformatories respectively before the turn of the century. Portals with Dutch Mannerist expressions were installed at the principal entrances as a publicly visible feature of modernisation for the repurposed complexes. This essay is a study of these architectural objects and their socio-political value for the city’s philanthropic campaign that affirmed middle-class power. It argues that the portals, completed with narrative relief panels and didactic inscriptions, were a means for Amsterdam’s authorities to redefine the spectacle of social marginality. Once a concrete sight of panhandlers and vagrants occupying the urban landscape, to the general population underclass visibility became an abstract image of civic discipline. Such an image enabled sequestered and disappeared lives to reappear, with a spectral quality integral to Foucault’s analysis of modern society’s compulsion to stow away indigent bodies. Considering the seventeenth-century Dutch moral geography of moderating wealth through philanthropy, such a ‘spectral spectacle’ paralleled the Baroque theatricality of Counter-Reformation Rome as a spatial experience that advanced a more secular mode of devotion to the community.

ORYX-MRSI: A Fully-Automated Open-Source Software for Three-Dimensional Proton Magnetic Resonance Spectroscopic Imaging Data Analysis

Proton magnetic resonance spectroscopic imaging (1H-MRSI) provides noninvasive evaluation of brain metabolism. However, there are some limitations of 1H-MRSI preventing its wider use in the clinics, including the spectral quality issues, partial volume effect and chemical shift artifact. Additionally, it is necessary to create metabolite maps for analyzing spectral data along with other MRI modalities. In this study, a MATLAB-based open-source data analysis software for 3D 1H-MRSI, called Oryx-MRSI, which includes modules for visualization of raw 1H-MRSI data and LCModel outputs, chemical shift correction, tissue fraction calculation, metabolite map production, and registration onto standard MNI152 brain atlas while providing automatic spectral quality control, is presented. Oryx-MRSI implements region of interest analysis at brain parcellations defined on MNI152 brain atlas. All generated metabolite maps are stored in NIfTI format. Oryx-MRSI is publicly available at https://github.com/sevimcengiz/Oryx-MRSI along with six example datasets.

Calibration Technique for Suppressing Residual Etalon Artifacts in Slit-Averaged Raman Spectroscopy

Back-illuminated charged-coupled device (BI-CCD) arrays increase quantum efficiency but also amplify etaloning, a multiplicative, wavelength-dependent fixed-pattern effect. When spectral data from hundreds of BI-CCD rows are combined, the averaged spectrum will generally appear etalon-free. This can mask substantial etaloning at the row level, even if the BI-CCD has been treated to suppress the effect. This paper compares two methods of etalon correction, one with simple averaging and one with row-by-row calibration using a fluorescence standard. Two BI-CCD arrays, both roughened by the supplier to reduce etaloning, were used to acquire Raman spectra of murine bone specimens. For one array, etaloning was the dominant source of noise under the exposure conditions chosen, even for the averaged spectrum across all rows; near-infrared-excited Raman peaks were noticeably affected. In this case, row-by-row calibration improved the spectral quality of the average spectrum. The other CCD’s performance was shot-noise limited and therefore received no benefit from the extra calibration. The different results highlight the importance of checking for and correcting row-level fixed pattern when measuring weak Raman signals in the presence of a large fluorescence background.

Spectral quality as an eliciting agent in the production of phenolic compounds in the callus of Hyptis marrubioides Epling

Hyptis marrubioides Epling is a species of the Brazilian cerrado traditionally used to treat gastrointestinal and cutaneous infections, pain, and cramps. The use of visible and ultraviolet C (UVC) radiation is a promising strategy to optimize the production of the bioactive metabolites. Therefore, the effect of the spectral quality of light on the production of metabolites was evaluated in H. marrubioides callus. The callus was inoculated on MS medium with 50% of the salt concentration containing 2 mg L-1 naphthaleneacetic acid (NAA) and 1 mg L-1 benzylaminopurine (BAP). The callus cultures were exposed for 20 days to the spectral qualities of white light, blue, red, and blue + red as well as to darkness. In addition, the callus cultivated under white light were exposed to UVC on the 21st day for 0, 30, 60, 120, and 240 seconds. The exposure of H. marrubioides callus to blue light negatively affects the synthesis of phenolic compounds. Red light stimulates the synthesis of caffeic acid and luteolin. Darkness was the best condition among those studied because it was associated with the increased accumulation of caffeic acid, chlorogenic acid, rosmarinic acid, and luteolin. The exposure of H. marrubioides callus cultivated under white light to UVC radiation promoted an increase in the synthesis of chlorogenic acid, ferulic acid, rosmarinic acid, and luteolin.

Layering contrasting photoselective filters improves the simulation of foliar shade

Background Neutral density shade cloth is commonly used for simulating foliar shade, in which it reduces light intensity without altering spectral quality. However, foliar shade also alters spectral quality, reducing the ratio of red to far-red (R:FR) light and altering the ratio of blue to green (B:G) light. Unlike shade cloth, photoselective filters can alter spectral quality, but the filters used have not simulated foliar shade well. We examined the spectral quality of sunlight under color temperature blue (CTB), plus green (PG), and neutral density (ND) filters from LEE Filters, Rosco e-colour+, and Rosco Cinegel brands either alone or layered, hypothesizing that the contrasting qualities of the different filters would improve simulations. As a proof-of-concept, we collected spectral data under foliar shade to compare to data collected under photoselective filters. Results Under foliar shade reductions in the R:FR ratio ranged from 0.11–0.54 (~ 1.18 in full sun), while reductions in the B:G ratio (~ 0.87 in full sun) were as low as 0.53 (deep shade), or were as high as 1.11 (moderate shade). Neutral density filters led to near-neutral reductions in photosynthetically active radiation and reduced the R:FR ratio similar to foliar shade. Color temperature blue filters simulated the increased B:G ratio observed under moderate foliar shade; however, these filters did not reduce the R:FR ratio low enough. On their own, PG filters did not simulate any type of foliar shade. Different brands of the same filter type also had disparate effects on spectral quality. Layered CTB and ND filters improved the accuracy of moderate foliar shade simulations, and layering CTB, PG, and ND filters led to accurate simulations of deep foliar shade. Conclusions Layering photoselective filters with contrasting effects on the spectral quality of sunlight results in more accurate simulations of foliar shade compared to when these filters are used separately. Layered filters can re-create the spectral motifs of moderate and foliar shade, and could be used to simulate shade scenarios found in different cropping systems. Photoselective filters offer numerous advantages over neutral density shade cloth, and could be a direct replacement for researchers using neutral density shade cloth in their experiments.

Harmonics control of three phase voltage source inverter with random carriers and modified reference

The Harmonics control of any inverters can be decided by the PWM incorporated for the switches. In recent years the carrier and reference modification based research is going on the inverter field. This paper suggests that the alteration of carriers and references of the three phase voltage source inverter enhance the ability to decrease the harmonic content.This enhanced realization deals with the carrier and reference modification arrangement for three phase voltage source inverter through amalgamating the boosted reference and random triangular carrier. The boosted reference is the addition of sine reference with injection of 1/3rd of reference amplitude (3fs) in the middle portion of the reference wave. i.e., [Formula: see text] to [Formula: see text] and [Formula: see text] to [Formula: see text] . The proposed PWM scheme use two carriers, one is Triangle wave and another one is inverted Triangle wave. The process of selecting the winning carrier among the two triangle carriers is purely based on the LFSR technique. The spectral quality of the induction motor drives has improved by the random carriers. The simulation and experimental values are proving the validity of the PWM method. The PWMs are generated by using parallel processing enabled FPGA processor.