Detection of eye strain through blink rate and sclera area using raspberry-pi

In this paper, a unique approach is proposed to determine eye strain in children caused due to the prolonged exposure to LCD and PDP screens. Blink rate and area of eye sclera are the two efficient metrics relied upon to determine eye strain. Initially, blink rate is computed by monitoring state transitions from open to closed eyes. To segment the sclera region of the eye Otsu’s thresholding and colour tracking, were implemented. These approaches had limitations due to illumination and skin tone. To overcome this, Modified Otsu using Colour Tracking is proposed in this paper. The occurrence of eye strain is determined by comparing the values of the metrics derived in real time with a threshold. The proposed algorithm detects eye strain with an accuracy of 83%. After detection of fatigue an alert message is sent to caretakers.     

不同书面阅读时长下照明对视疲劳和大脑唤醒水平的影响

目的探究0~120 min阅读时间内,照度色温对视疲劳及大脑唤醒水平的影响。方法在0~120 min阅读时间内,通过采集和分析被试在不同照度、色温组合下的眼动数据及阅读速度数据,研究阅读时间内照度和色温对视疲劳及大脑唤醒水平的影响。结论 60 min内随着照度和色温的增加,瞳孔直径变异系数减小,眨眼频率增高,照度增加时阅读速度无明显变化,色温增加则阅读速度加快。在60,90,120 min时,瞳孔直径变异系数和阅读速度变化明显,30 min内各因变量变化不明显。0~120 min阅读时间内,照度、色温对平均注视持续时间影响不显著。     

Effect of packaging materials and storage conditions on bacterial growth,off‐odour,pH and colour in chicken breast fillets

A comparison was made of the effect of different packaging materials on bacterial growth, off‐odour, pH and colour of chicken breast fillets stored at 4°C. For one of the packaging materials, the effects of temperature (4°C and 8°C) and initial oxygen present (0%, 2% and 4%) on bacterial growth, off‐odour, pH and colour in chicken breast fillets were also evaluated. Chicken breast fillets stored in the packaging material with the highest oxygen transmission rate (OTR) measured at actual storage conditions had the highest bacterial growth and the highest degree of off‐odour. Chicken breast fillets stored in packaging material mainly consisting of expanded PET had similar bacterial growth and off‐odour as in the barrier display film (BDF) packages, despite a smaller headspace volume and lower initial concentration of CO₂. No differences in discoloration and pH of the chicken breast fillets, due to storage temperature and amount of initial oxygen present, were found when one of the packaging materials was studied. In the early phase of the storage period, Pseudomonas spp. constituted the majority of the total viable counts, while after about 12 days, lactic acid bacteria dominated. At the end of the storage period, both Pseudomonas spp. and Enterobacteriaceae were present in high numbers. Significant differences in counts of Brochothrix thermosphacta were only obtained with initial presence of oxygen. The storage temperature had greater impact on microbial growth and off‐odour than the initial presence of oxygen in the packages. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of gas mixing ratio on gas-phase composition and etch rate in an inductively coupled CF4/Ar plasma

In this work, we carried out investigations aimed at understanding the effect of gas mixing ratio on plasma parameters, gas phase composition and etch rate in CF₄/Ar inductively coupled plasma. For this purpose, a combination of experimental methods and modelling was used. Experiments showed that electron temperature and electron density are not very sensitive to variations of Ar content in CF₄/Ar plasma. From a zero-dimensional plasma model, the densities of both neutral and charged particles change monotonically. The analysis of surface kinetics based on an ion-assisted etching mechanism showed the possibility of non-monotonic etch rate behaviour due to a concurrence of chemical and physical etching pathways.     

Effect of cooling rate on microstructure,microsegregation and mechanical properties of cast Ni-based superalloy K417G

The effects of different solidification rates after pouring on the microstructures,microsegregation and mechanical properties of cast superalloy K417 G were investigated.Scheil-model was applied to calculate the temperature range of solidification.The casting mould with different casting runners was designed to obtain three different cooling rates.The microstructures were observed and the microsegregation was investigated.Also,high temperature tensile test was performed at 900?C and stress rupture test was performed at 950?C with the stress of 235 MPa.The results showed that the secondary dendrite arm spacing,microsegregation,the size and volume fraction of γ'phase and the size of γ/γ'eutectic increased with decreasing cooling rate,but the volume fraction of γ/γ' eutectic decreased.In the cooling rate range of 1.42?C s~(-1)–0.84?C s~(-1),the cast micro-porosities and carbides varied little,while the volume fraction and size of phase and γ/γ' eutectic played a decisive role on mechanical properties.The specimen with the slowest cooling rate of 0.84?C s~(-1) showed the best comprehensive mechanical properties.     

Influence of growth rate on the structural and morphological properties of TiN, ZrN and TiN/ZrN multilayers

The effect of the deposition rate on the structural and morphological properties of TiN and ZrN single layers and TiN/ZrN multilayers deposited by radiofrequency reactive magnetron sputtering has been studied. The total pressure was kept constant and the growth rate variation was obtained by small difference of nitrogen concentration in the fed gas. The decreasing deposition rate results in a structural change in the thin films from (111) orientation to (100) one. As consequence the surface morphology becomes smoother. Films roughness is strongly related with texture and it decreases with an increase in the (100) X-ray diffraction line intensity. In order to achieve a clear interpretation of our experimental results, the ratio between the N⁺ ions of the plasma and the atoms number reaching the substrate was considered. At high deposition rate with respect to the N⁺ concentration, the chemical potential of transition metal on (100) growth surface is higher than (111) one favouring the (111) orientation of the films. On the contrary, when the growth rate is low with respect to the nitrogen concentration, the chemical potential of transition metal on (111) growth surface is higher than the (100) one leading to a preferential growth in the (100) direction.     

Effect of stitching and weave architecture on the high strain rate compression response of affordable woven carbon/epoxy composites

In this study, experimental investigations on stitched and unstitched woven carbon/epoxy laminates under high strain rate compression loading are discussed. Stitched/unstitched laminates are fabricated with aerospace grade plain and satin weave fabrics with room temperature curing SC-15 epoxy resin using affordable vacuum assisted resin infusion molding process. The samples are subjected to high strain rate loading using modified compression split Hopkinson’s pressure bar at three different strain rates ranging from 320 to 1149 s⁻¹. Results are discussed in terms of unstitched/stitched configuration, fabric type and loading directions. Dynamic compression properties are compared with those of static loading. Failure mechanisms are characterized through optical and scanning microscopy.     

Effect of gas Mach number on the flow field of close-coupled gas atomization,particle size and cooling rate of as-atomized powder: Simulation and experiment

Gas velocity is a key parameter regulating the particle size and the cooling rate of the gas atomized powder applied in additive manufacturing, metal injection molding, thermal spraying, and soft magnetic composites. In this paper, on basis of the well-designed close-coupled nozzles with different gas Mach numbers at the outlet, the gas field structure was simulated by Computational Fluid Dynamics (CFD) software, and the process of cooling and solidification of Fe-6.5 wt% Si metal droplets was calculated by finite difference method. The results show that with the increase of Mach number, both the gas velocity downstream and the pressure at the base of melt delivery tube tip rise, whereas the mass flow rate of the melt decreases. The nozzles with high Mach number can produce finer powder with higher cooling rate. The median diameter of the powder prepared by the nozzle with Mach numbers of 1.0, 1.5, 2.0, and 2.5 is 44.9, 39.0, 32.5, and 29.1 μm, respectively, and the corresponding cooling rate of the metal droplet with a diameter of 80 μm is 2.85 × 10⁴, 2.98 × 10⁴, 3.32 × 10⁴, and 3.50 × 10⁴ K/s, respectively. This work provides new ideas and suggestions for the preparation of metal powder with small particle size at high cooling rate.     

Effect of incident nocturnal home hemodialysis versus incident continuous ambulatory peritoneal dialysis on employment rate,clinical, and laboratory outcomes: A 1‐year retrospective observation study

Introduction: While studies demonstrated favorable outcomes of nocturnal home hemodialysis (NHHD), direct comparison on employment rate, clinical and laboratory outcomes between the NHHD and continuous ambulatory peritoneal dialysis (CAPD) had not been previously performed. Methods: A 1‐year retrospective observation study was performed in 20 incidents alternate night NHHD and 81 incident CAPD patients of Chinese ethnicity, who were sex, diabetic status, and Charlson comorbidity index matched, but not age due to our center's age limit for NHHD enrollment. The primary outcome was the difference in employment rate at 1 year. Secondary outcomes included differences in clinical parameters (weight, blood pressure, number of antihypertensive medication, dosage of phosphate binders, and erythropoietin stimulating agent) and laboratory parameters (residual renal function, mineral metabolic markers, hemoglobin). Findings: NHHD subjects were 5 years younger than CAPD patients, and they had higher employment rate (80% vs. 33.3%, P < 0.01) at 1 year, with age‐adjusted odds ratio for employment was 6.10 (95% confidence interval 1.77–20.99, P = 0.04). They consumed less aluminum‐based phosphate binder (0 vs. 1800 mg, P < 0.01), but showed no significant disparities in other clinical parameters. Residual renal function in both groups declined comparably, nonetheless NHHD group had lower serum phosphate (1.37 vs. 1.71 mmol/L, P = 0.01) and calcium phosphate product (3.13 vs. 4.12 mmol²/L², P < 0.01), with similar hemoglobin levels. Discussion: NHHD appeared to offer higher employment rate, lower dosage of aluminum‐based phosphate binder and mineral metabolic markers at 1 year compared with CAPD in Hong Kong.     

Effect of dehydration rate on non-hydrolytic TiO2 thin film processing: Structure,optical and photocatalytic performance studies

The influence of complexing agent diethanolamine (DEA) on the rate of dehydration due to hydrolysis in titania thin films prepared by non-aqua sol–gel process was investigated. The formation of complex with titanium precursor controls the rate of hydrolysis over wide range of temperature. The rate of hydrolysis with respect to complex formation and firing temperate was studied by using thermogravimetry and differential thermal analysis (TG–DTA). The role of complexing agent in the crystallization of anatase and phase transformation to rutile was studied by X-ray diffraction (XRD). Effect of complexing agent on the optical transmittance in the visible range was monitored by ultraviolet–visible absorption spectroscopy. Photocatalytic performance of the titania films was measured using methylene blue (MB) as the model contaminant. Mechanical characteristics such as hardness and adhesion of the film were rated by using scratch tests as per ASTM standards.     

Effect of NH3 flow rate on growth, structure and luminescence of amorphous silicon nitride films by electron cyclotron resonance plasma

In this paper, hydrogenated amorphous silicon nitride (a-SiN_x:H) films have been deposited using an electron cyclotron resonance chemical vapor deposition system. The effect of NH₃ flow rate R on the deposition rate, structure and luminescence were studied using various techniques such as optical emission spectroscopy, Fourier Transform Infrared absorption (FTIR), X-ray photoelectron spectroscopy (XPS) and fluoro-spectroscopy, respectively. Optical emission behavior of SiH₄ + NH₃ plasma shows that atomic Si radical concentration determines the film deposition rate. Structural transition of a-SiN_x film from Si-rich one to near-stoichiometric/N-rich one with R was revealed by FTIR and the two phase separation of a-Si and a-Si₃N₄ was also convinced in Si-rich SiN_x films by XPS. Either photo- or electroluminescence for all the SiN_x films with R > 3 sccm shows a strong light emission in visible light wavelength range. As R < 6 sccm, recombination of electrons and holes in a-Si quantum dots is the main mechanism of photo/electroluminescence for Si-rich SiN_x films, however, for photoluminescence, gap states' luminescence is also in competition; as R > 6 sccm, light emission of the SiN_x film originates from defect states in its band gap.     

Comparison of creep crack growth rate in heat affected zone of welded joint for 9%Cr ferritic heat resistant steel based on C, dδ/dt, K and Q parameters

Creep crack growth behavior is very sensitive to the materials’ micro-structures such as the heat affected zone of a weld joint. This is a main issue to be clarified for 9%Cr ferritic heat resistant steel for their application in structural components. In this paper, high temperature creep crack growth tests were conducted on CT specimens with cracks in the heat affected zone of weld joints of W added 9%Cr ferritic heat resistant steel, ASME grade P92. The creep crack growth behavior in the heat affected zone of welded joint was investigated using the Q^∗ concept following which the algorithm of predicting the life of creep crack growth has been proposed. Furthermore, three-dimensional elastic-plastic creep FEM analyses were conducted and the effect of stress multiaxiality of welded joint on creep crack growth rate was discussed as compared with that of base metal.     

Impact of the Se evaporation rate on the microstructure and texture of Cu(In,Ga)Se2 thin films for solar cells

Coevaporated Cu(In,Ga)Se₂ layers on Mo-coated soda-lime glass substrates were produced by a three-stage process using various Se overpressure conditions during the three stages. Cross-sections of these samples were analyzed by electron backscatter diffraction (EBSD) in a scanning electron microscope in order to reveal the microstructures in the Cu(In,Ga)Se₂ layers. In addition, the preferential orientations of these Cu(In,Ga)Se₂ layers were studied by plan-view EBSD measurements. It was found that Cu(In,Ga)Se₂ exhibits a texture in 110 orientation for Se/(Cu + In + Ga) atomic flux ratios R which are sufficiently large (≥ 4). In one Cu(In,Ga)Se₂ layer produced with approximately R = 4, a large density of (near) Σ3 (twin) boundaries were detected which are oriented preferentially perpendicular to the substrate. By comparison of the local textures of neighboring grains and the theoretically possible changes in orientation by twinning, it is possible to retrace how the twinning occurred.