Variation Of Light Intensity Research Articles

Design and Analysis of Micro-Opto-Mechanical System Cantilever Integrated with Photonics Waveguide for Pressure Sensing Applications

In this work, the pressure sensing approach based on the Micro-Opto-Mechanical System (MOMS) cantilever integrated with waveguide structure has been explored. The MOMS based photonic sensors are drawing attention because of their high sensing capabilities. In the design of MOMS based cantilever pressure sensor, mainly two different waveguide structures, Rib and Slot waveguides have been considered. The deviation in light intensity at the output of the waveguide structure is mainly used to analyze the amount of exerted pressure at the free-end of cantilever. Using the different waveguide parameters such as, effective mode area, light intensity variations, etc., the performance comparison between Rib and Slot waveguides have been done. The relationship between the normalized light intensity at the waveguide output corresponding to the applied pressure has been established from the relationship between the deflection versus pressure and normalized intensity versus deflection. It has been anticipated that the performance of pressure sensor using Slot waveguide is significantly better than the Rib waveguide for some application.

Data Rate Enhancement in Optical Camera Communications Using an Artificial Neural Network Equaliser

In optical camera communication (OCC) systems leverage on the use of commercial off-the-shelf image sensors to perceive the spatial and temporal variation of light intensity to enable data transmission. However, the transmission data rate is mainly limited by the exposure time and the frame rate of the camera. In addition, the camera's sampling will introduce intersymbol interference (ISI), which will degrade the system performance. In this paper, an artificial neural network (ANN)-based equaliser with the adaptive algorithm is employed for the first time in the field of OCC to mitigate ISI and therefore increase the data rate. Unlike other communication systems, training of the ANN network in OCC is done only once in a lifetime for a range of different exposure time and the network can be stored with a look-up table. The proposed system is theoretically investigated and experimentally evaluated. The results record the highest bit rate for OCC using a single LED source and the Manchester line code (MLC) non-return to zero (NRZ) encoded signal. It also demonstrates 2 to 9 times improved bandwidth depending on the exposure times where the system's bit error rate is below the forward error correction limit.

Effect of Intensity of Light and Size of the Touch Screen on Data Entry Through Mobile Phones by Different Age Group People: An Ergonomic Perspective

The performances of the operators are affected by industrial lighting over the wide range of working stations to accomplish the task. This research investigated the performance of the subjects on different smartphones under the influence of varying light intensities. Fourteen participants (7 older adults and 7 younger adults) were chosen to enter the data on smartphones of display sizes 5.8 inches and 6.2 inches. The German script was taken to type on the mobile at light intensities of 200lx, 400lx, and 600 lx. The data entry lasted for ten minutes and the number of words types was statistically analyzed. Younger adults and an older one, both the users entered more words on the iPhone X (size of 5.8”) than on Samsung Galaxy S9+(size of 6.2”). The average number of words entered increases from 78 to 88.71 as the light intensity increases from 200 lx to 600 lx on iPhone X by younger adults while on Samsung Galaxy S9+ the average number increases from 78.14 to 81. Similarly, the average number of words entered by the older adult increases from 70.14 to 75.14 on smaller mobiles and 68 to 70.71 on larger mobiles. The outcomes from the SPSS illustrated the effects of ages, mobile sizes, and light intensity found to be statistically significant. Simultaneously the interaction of age with light intensity and size of mobiles with light intensity as well as the interactions amongst all the three parameters are found to be significant.

Determination of Fill Factor and Efficiency in Solar Cell Type (99 × 69) mm2 with Arduino Uno R3 Based Drive assisted by Logger Pro 3.14.1

Abstrak- The study about fill factor and efficiency solar cell have been done with an automatic drive machine that rotates the surface of the solar cell following the movement of the light source from 0° up to 90° compared without automatic drive. The test results are then implemented to determine the fill factor and efficiency in variations in light intensity. In this study, polycrystalline solar cell type (99 × 69) mm2, the Philips 100W/220V light bulb at a distance of 18 cm and the driving machine is controlled through an Arduino Uno R3 microcontroller. Data acquisition of current and voltage is carried out with the help of DCP-BTA current and VP-BTA voltage probes that are connected to the mini labquest transducer and displayed to a computer through loggerpro software. The result show that it has been successfully designed an automatic driver of a solar panel (99 × 69) mm2 with an Arduino Uno R3 microcontroller and a logger pro software as data acquisition software. The using solar cell automatically driven can improve the accuracy and precision of current and voltage readings so the fill factor might be increased up to 10% while the efficiency of solar cells does not change. Variations in light intensity can increase the fill factor and efficiency of solar cells. Fill factor and efficiency have an exponentially relationship to light intensity.

Non Contact Heart Rate Monitoring using Facial Video

Heart rate (HR) is a direct measure of heart’s function. Conventional measurement based on contact-based measurement may cause discomfort to patients, especially in the case of long-term monitoring. This paper proposes a non-contact method of measuring heart rate using facial video of the patient. The variation of light intensity from the skin from each heart beat is used to estimate HR. A standard RGB camera is used to record the video. The Region of Interest (ROI) is obtained using face detection and tracking algorithms. A mean is taken across the frame yielding three values per frame. The Photo Plethysmo Graphy(PPG) signal is isolated using Independent Component Analysis (ICA). The signals are further filtered to reduce out of band noise and improve accuracy. The Fast Fourier Transform (FFT) is used to convert the signal to frequency domain and the peak is identified, whose frequency will correspond to the HR. This method of measuring HR has several advantages over conventional methods. HR measurement during exercise, prisons where contact-based methods cannot be employed, and long-term HR measurement in hospitals are some applications where the proposed method will be highly advantageous. The method also reduces the amount of hardware needed for HR measurement; HR can be measured even using smartphones.

An intensity-modulated and large bandwidth magnetic field sensor based on a tapered fiber Bragg grating

An intensity-modulated and large bandwidth magnetic field fiber sensor with tapered fiber Bragg grating (TFBG) had been proposed and demonstrated by experiments. Fiber Bragg grating (FBG) was created into a tapered fiber to form TFBG, which not only had powerful evanescent field but also possessed large bandwidth for the fiber refractive index decreased along the tapered region. The TFBG inserted into a 0.3 mm diameter glass tube which was filled with the magnetic-fluid (MF), and then this structure was packaged to form an integration magnetic-field fiber sensor. The refractive index of the MF will changed under varied magnetic-field, so the reflection spectral of the sensor should have a corresponding changed with the magnetic-field changed due to the tunable refractive index of MF. We designed the experiments and tested the sensor. The experimental results show that a nonlinear curve is between light intensity variation and changed MF intensity variation, the uniformity fitting degrees are 0.999 and 0.996 among the magnetic field increased and declined and the maximum sensitivity is −0.1933 dB/Oe and −0.1533 dB/Oe, respectively. Moreover, we find magnetic hysteresis has no obvious affection on the magnetic vectors (0 and 180 deg). This proposed magnetic-field sensor has the benefits of no direction disturbance, large bandwidth, high sensitivity, and integration.

Cones Support Alignment to an Inconsistent World by Suppressing Mouse Circadian Responses to the Blue Colors Associated with Twilight.

SummaryIn humans, short-wavelength light evokes larger circadian responses than longer wavelengths [1, 2, 3]. This reflects the fact that melanopsin, a key contributor to circadian assessments of light intensity, most efficiently captures photons around 480 nm [4, 5, 6, 7, 8] and gives rise to the popular view that “blue” light exerts the strongest effects on the clock. However, in the natural world, there is often no direct correlation between perceived color (as reported by the cone-based visual system) and melanopsin excitation. Accordingly, although the mammalian clock does receive cone-based chromatic signals [9], the influence of color on circadian responses to light remains unclear. Here, we define the nature and functional significance of chromatic influences on the mouse circadian system. Using polychromatic lighting and mice with altered cone spectral sensitivity (Opn1mwR), we generate conditions that differ in color (i.e., ratio of L- to S-cone opsin activation) while providing identical melanopsin and rod activation. When biased toward S-opsin activation (appearing “blue”), these stimuli reliably produce weaker circadian behavioral responses than those favoring L-opsin (“yellow”). This influence of color (which is absent in animals lacking cone phototransduction; Cnga3−/−) aligns with natural changes in spectral composition over twilight, where decreasing solar angle is accompanied by a strong blue shift [9, 10, 11]. Accordingly, we find that naturalistic color changes support circadian alignment when environmental conditions render diurnal variations in light intensity weak/ambiguous sources of timing information. Our data thus establish how color contributes to circadian entrainment in mammals and provide important new insight to inform the design of lighting environments that benefit health.

Combustion Properties of Impregnated and Heat-Treated Wood Material

The use of heat-treated wood material and eco-friendly impregnation chemicals are steadily increasing in the woodworking industry over the last decades. In this study, the effects of applications of impregnation and heat treatment on combustion properties of Hornbeam (Carpinus betulus L.) wood were investigated. The test specimens were impregnated with Imersol-aqua (Ia) and Timbercare-aqua (Ta) impregnation material according to ASTM D 1413-76 standards. Impregnated specimens were subjected to heat treatment at 150, 170 and 190 °C for 2 h. The temperature of flame source combustion, the temperature of without flame source combustion and varying light intensities (Lux) depending on the smoke production in these combustion stages were determined according to ASTM E 160-50. According to the test results, the highest combustion temperature of flame source combustion was determined in unimpregnated and heat-treated samples at 190 °C, while the highest combustion temperature of without flame source combustion was determined in impregnated with Ta and heat-treated samples at 170 °C. The highest light density in flame source combustion phase was determined in unimpregnated and heat-treated samples at 190°C, while in without flame source combustion was in unimpregnated and heat-treated samples at 170°C. As a result, as the heat treatment temperature increase, the combustion temperature increased and the smoke density decreased. In addition to impregnation materials increased the smoke density while reduced the combustion temperatures of test specimens.

Naive Bayesian classifier for hydrophobicity classification of overhead polymeric insulators using binary image features with ambient light compensation

Dispersion nature of water droplets over the insulator surface is used for hydrophobicity classification. Stochastic nature of water dispersions makes naive Bayesian classifier a preferable choice, which has been investigated in this work. About 12 features describing the characteristics of water droplets are extracted from the binary image using binary large objects analysis. Ambient light intensity is a significant factor that affects the binary image quality. As these insulators are installed in the outside environment, variations in ambient light intensity are inevitable. An adaptive threshold technique is proposed to compensate for ambient light variations. Six classes of various ambient light intensities have been considered in this study, and the proposed adaptive threshold technique can produce quality binary image consistently. Features extracted from the binary image are ordered according to their principal components (PCs) using PC analysis. Improvement in classification accuracy with the accumulation of ordered features is analysed. Results illustrate the use of the first eight features provides a reliable classification accuracy of 97.6% for test image samples. In comparison to the other existing classifiers, the proposed classifier illustrates optimal performance in terms of classification accuracy and computational time.

Photovoltaic and capacitance measurements of solar cells comprise of Al-doped CdS (QD) and hierarchical flower-like TiO2 nanostructured electrode

This work focuses on the performance of Al-doped CdS quantum dot (QD)/TiO2 solar cells. The devices were analyzed through current-voltage and capacitance-voltage measurements. It was observed from the analysis of absorption spectra that TiO2 nanowires improve the absorption of light of Al doped CdS QDs both in visible and near infrared (NIR) range. Current-voltage characteristics curve of Al doped CdS/TiO2 at different illuminations show that decrease in illumination (from 100 to 5 mW/cm2), affects the voltage and current correspondingly. Power-voltage curve at various intensities of light indicates that power of the solar cell increases with the increase of the bias voltage and reaches its maximum value at each value of light illumination intensity. The peak value of power at maximum illumination is 35 µW at 0.20 V and with decreasing illumination the peak value decreases. Capacitance-voltage measurements reveal that by increasing the bias voltage from −2.0 V to 0 V, the capacitance voltage indicates the rising trend. However, at 5 kHz and 10 kHz frequencies, it was observed that a marginal increase of capacitance was noticed with exceeding bias voltage. The results revealed that subsequent addition of the TiO2 nanowires significantly improved the output performance of QDSSC.

Net heterotrophy and carbonate dissolution in two subtropical seagrass meadows

Abstract. The net ecosystem productivity (NEP) of two seagrass meadows within one of the largest seagrass ecosystems in the world, Florida Bay, was assessed using direct measurements over consecutive diel cycles during a short study in the fall of 2018. We report significant differences between NEP determined by dissolved inorganic carbon (NEPDIC) and by dissolved oxygen (NEPDO), likely driven by differences in air–water gas exchange and contrasting responses to variations in light intensity. We also acknowledge the impact of advective exchange on metabolic calculations of NEP and net ecosystem calcification (NEC) using the “open-water” approach and attempt to quantify this effect. In this first direct determination of NEPDIC in seagrass, we found that both seagrass ecosystems were net heterotrophic, on average, despite large differences in seagrass net above-ground primary productivity. NEC was also negative, indicating that both sites were net dissolving carbonate minerals. We suggest that a combination of carbonate dissolution and respiration in sediments exceeded seagrass primary production and calcification, supporting our negative NEP and NEC measurements. However, given the limited spatial (two sites) and temporal (8 d) extent of this study, our results may not be representative of Florida Bay as a whole and may be season-specific. The results of this study highlight the need for better temporal resolution, accurate carbonate chemistry accounting, and an improved understanding of physical mixing processes in future seagrass metabolism studies.

Gap Junction Coupling Shapes the Encoding of Light in the Developing Retina.

Detection of ambient illumination in the developing retina prior to maturation of conventional photoreceptors is mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) and is critical for driving several physiological processes, including light aversion, pupillary light reflexes, and photoentrainment of circadian rhythms. The strategies by which ipRGCs encode variations in ambient light intensity at these early ages are not known. Using unsupervised clustering of two-photon calcium responses followed by inspection of anatomical features, we found that the population activity of the neonatal retina could be modeled as six functional groups that were composed of mixtures of ipRGC subtypes and non-ipRGC cell types. By combining imaging, whole-cell recording, pharmacology, and anatomical techniques, we found that functional mixing of cell types is mediated in part by gap junction coupling. Together, these data show that both cell-autonomous intrinsic light responses and gap junction coupling among ipRGCs contribute to the proper encoding of light intensity in the developing retina.

The current and voltage curves simulation solar module using IV tracer networks

Simulation is done to see that the output parameter value of a solar module. Output produced a solar module as measured manually does not provide information that solar modules working at optimal power. Information on the performance of a solar module can be done with a piece of equipment called IV Tracer. IV Tracer work to collect data by varying the value of the working voltage of solar modules ranging from short circuit to open relations. IV Tracer circuits using MOSFETs IRF540 with snubber circuits produce 52 samples of data for 506 mS. The shape of the characteristic curve of current and voltage (IV) produced in accordance with the datasheet PSIM with the fill factor of 0.71.IV Tracer circuit can generate output parameters according to the theory of power changes to variations in temperature values of 0.05% and variations in light intensity of 0.14%. IV Tracer circuit with MOSFET switching system and may dampen stepping snubber circuit voltage of -0.2 V in accordance with the solar module to be tested.

Hand Vein Recognition Algorithm Based on NMF with Sparsity and Clustering Property Constraints in Feature Mapping Space

Most of the existed vein features are lack of robustness to light intensity variation, and some algorithms rely on the specified vein data sets, which leads to the limitation of real applications. To solve the problems, we propose a novel vein recognition algorithm based on Nonnegative matrix factorization (NMF) with double regularization terms. The innovations of our algorithm are mainly reflected in the following two aspects: in order to improve feature robustness, a novel feature mapping function is designed to map the initial Histogram of oriented gradient (HOG) feature to a new space; to enhance the recognition performance, an effective NMF model is presented, which not only reduces feature dimension, but also optimizes the feature sparsity and clustering property simultaneously. Experiments show that the proposed algorithm can achieve satisfactory results in terms of False rejection rate (FRR) and False acceptance rate (FAR), which indicates that our algorithm is valuable for other classification problems.

Sistem Arus-Votan yang Murah dengan Rintangan Terkawal-Elektronik di bawah Lampu Xenon Arka untuk Pengukuran Kecekapan Sel Suria

Crystalline silicon solar cell efficiency is required in order to accurately determine its performance and evaluate the fabrication process. Extensive automation has led to development of expensive instrumentation. In this study, simple, inexpensive method for measuring solar cell efficiency is reported. A controllable direct current (dc) illumination intensity method based on low power xenon arc lamps was designed and constructed. Low resistance electrical contacts were formed with conventional front surface probes and back surface Au-plated metal plate with vacuum attachment. In order to measure current-voltage (I-V) response, variable resistance approach was chosen. Commercially available, low cost electronic loads power supply is used to precisely vary resistance while measuring cell voltage and current. The resistance is controllably varied from a short circuit to an open circuit position on the I-V curve while measuring cell voltage and current. Plotting current as a function of voltage generates the characteristic solar cell I-V response. Solar cell efficiency measurements were recorded and plotted using LabVIEW program. The light intensity was varied by increasing number of high intensity discharge (HID) 50 W from 1 to four in order to vary respective illumination intensities from 330 to 1200 W/m2 range. The variation in light intensity was aimed at investigation of the electronic loads power supply at low and high currents. This I-V tester has been applied to different types of solar cell to validate its performance. Solar cells measured as part of this study included commercial silicon solar cell and laboratory solar cells with phosphorus oxytrichloride (POCl3) and phosphoric acid (H3PO4) emitter formation. This I-V measurement system for commercial cell exhibited an efficiency of 15.83% and efficiency of 16.2% and 13.3% for solar cells with POCl3 and H3PO emitters.

Low drift nuclear spin gyroscope with probe light intensity error suppression**Project supported by the National Key Research and Development Program of China (Grant Nos. 2016YFB0501600 and 2017YFB0503100) and the National Natural Science Foundation of China (Grant Nos. 61773043, 61673041, and 61721091).

A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxation-free (SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. However, the fluctuation of probe light intensity is one of the main technical error sources that limits the bias stability of the gyroscope. Here we propose a novel method to suppress the bias error induced by probe light intensity fluctuations. This method is based on the inherent magnetic field response characteristics of the gyroscope. By the application of a bias magnetic field, the gyroscope can be tuned to a working point where the output signal is insensitive to probe light intensity variation, referred to herein as ‘zero point’, thus the bias error induced by intensity fluctuations can be completely suppressed. The superiority of the method was verified on a K–Rb–21Ne co-magnetometer, and a bias stability of approximately 0.01 °/h was obtained. In addition, the method proposed here can remove the requirement of the closed-loop control of probe light intensity, thereby facilitating miniaturization of the gyroscope volume and improvement of reliability.

Photochemical and biochemical responses of heliconia (Heliconia stricta ‘Iris’) to different light intensities in a humid coastal environment

A field experiment was conducted to evaluate the performance of heliconia (Heliconia stricta ‘Iris’) grown under four levels of photosynthetically active radiation (PAR) in a randomized block design. Photochemical and biochemical parameters were recorded to assess the physiological and biochemical changes in heliconia that accompany varying light intensities. The plants grown under the lowest PAR (30 to 35% of open condition) showed enhanced growth with a higher biomass accumulation, plant height, suckering habit, emergence of flowering shoots, inflorescence yield, and light use efficiency. The leaves exposed to high PAR (open condition) recorded reduction in chlorophyll content (60.8%), chlorophyll index (43.9%), and Fv/Fm (21.4%) compared to values for the leaves exposed to the lowest PAR (30 to 35%). Plant soluble sugars were reduced with the increasing PAR, whereas reducing sugar content was high under fully irradiated conditions but showed a decreasing trend with a reduction in PAR. Total phenolic content and malondialdehyde were lower at 30 to 35% PAR with a reduction in magnitude of 58.4% and 34.8%, respectively, compared to the open condition. Similarly, super oxide dismutase, peroxidase, and polyphenol oxidase activities in the leaf decreased 36.2%, 28.7%, and 23.3%, respectively, from the highest PAR (or open condition) in this range. Improved photochemical and biochemical activities of plants grown under lower light intensities resulted in production of quality inflorescences. Hence, Heliconia stricta ‘Iris’ can be recommended as an intercrop on coconut plantations where the light intensity is low (30 to 35%) for improving the livelihood of farmers.

Optogenetically-Induced Population Discharge Threshold as a Sensitive Measure of Network Excitability.

Network excitability is governed by synaptic efficacy, intrinsic excitability, and the circuitry in which these factors are expressed. The complex interplay between these factors determines how circuits function and, at the extreme, their susceptibility to seizure. We have developed a sensitive, quantitative estimate of network excitability in freely behaving mice using a novel optogenetic intensity-response procedure. Synchronous activation of deep sublayer CA1 pyramidal cells produces abnormal network-wide epileptiform population discharges (PDs) that are nearly indistinguishable from spontaneously-occurring interictal spikes (IISs). By systematically varying light intensity, and therefore the magnitude of the optogenetically-mediated current, we generated intensity-response curves using the probability of PD as the dependent variable. Manipulations known to increase excitability, such as sub-convulsive doses (20 mg/kg) of the chemoconvulsant pentylenetetrazol (PTZ), produced a leftward shift in the curve compared to baseline. The anti-epileptic drug levetiracetam (LEV; 40 mk/kg), in combination with PTZ, produced a rightward shift. Optogenetically-induced PD threshold (oPDT) baselines were stable over time, suggesting the metric is appropriate for within-subject experimental designs with multiple pharmacological manipulations.

Charge Carrier Dynamics in Electron-Transport-Layer-Free Perovskite Solar Cells

Better understanding of the carrier dynamics process in electron-transport-layer (ETL)-free perovskite solar cells (PSCs) enables further exploration of the perovskite potential and corresponding device structure design. Herein, an ETL-free perovskite/transparent conductive film SnO2:F(FTO) contact with different perovskite thicknesses illuminated by varied light intensities were investigated by scanning probe microscopy technology. Strong charge transfer occurs at the perovskite/FTO contact, evidenced by the variations of both the surface contact potential and local current value. Mott–Schottky analysis based on capacitance–voltage measurements suggests that the interface property of the perovskite/FTO contact is similar to that of the perovskite/TiO2/FTO structure, making it ideal for fabricating ETL-free PSCs. The cross-sectional surface potential drop was found to be mainly located at the CH3NH3PbI3/FTO heterojunction, suggesting a single diode junction in the ETL-free PSCs. Furthermore, a single-side abrupt p–n++ junction model is employed to illustrate the energy level alignment at the perovskite/FTO contact. This study will be helpful for understanding the carrier dynamics process and thus achieving high device efficiency in the ETL-free PSCs.

Ecophysiology of Chloromonas hindakii sp. nov. (Chlorophyceae), Causing Orange Snow Blooms at Different Light Conditions

Slowly melting snowfields in mountain and polar regions are habitats of snow algae. Orange blooms were sampled in three European mountain ranges. The cysts within the blooms morphologically resembled those of Chloromonas nivalis (Chlorophyceae). Molecular and morphological traits of field and cultured material showed that they represent a new species, Chloromonas hindakii sp. nov. The performance of photosystem II was evaluated by fluorometry. For the first time for a snow alga, cyst stages collected in a wide altitudinal gradient and the laboratory strain were compared. The results showed that cysts were well adapted to medium and high irradiance. Cysts from high light conditions became photoinhibited at three times higher irradiances (600 µmol photons m−2 s−1) than those from low light conditions, or likewise compared to cultured flagellates. Therefore, the physiologic light preferences reflected the conditions in the original habitat. A high content of polyunsaturated fatty acids (about 60% of total lipids) and the accumulation of the carotenoid astaxanthin was observed. They are regarded as adaptations to cope with extreme environmental conditions of snow that include low temperatures, freeze-thaw cycles, and variable light intensity. The intraspecific ability of adaptation of the photosynthetic apparatus to different irradiance regimes seems to be advantageous for thriving in different snow habitats.