A New Approach to Mixed/Boundary Friction Prediction Using the Logistics Curve

There is a strong focus on improving the energy efficiency of machines. Over the last 20-30 years, one way to improve energy efficiency has been to reduce lubricant viscosity. This also has the effect of leading to thinner oil films between the machine’s moving surfaces and is likely to lead to increased mixed/boundary friction. Accurately predicting friction in the mixed/boundary friction regime is therefore becoming of great importance. The work reported here suggests that commonly used asperity friction models significantly underestimate friction in the mixed/boundary friction, and a new model, based on a logistic curve fit, gives a better estimate of mixed/boundary friction, provides good agreement with experimental friction data (from Mini Traction Machine experiments), and is much more straightforward for engineers and tribologists to apply for the estimation of mixed/boundary friction losses.

Investigation of defect levels in Bi12SiO20 single crystals by thermally stimulated current measurements

Bi12SiO20 (BSO) single crystal belongs to the sillenite semiconducting family known as defective compounds. The present paper investigates the defect centers in BSO grown by Czochralski method by means of thermally stimulated current (TSC) measurements performed in the 10-260 K range. The TSC glow curve obtained at heating rate of β = 0.1 K/s presented several peaks associated with intrinsic defect centers. The activation energies of defect centers were revealed as 0.09, 0.15, 0.18, 0.22, 0.34, 0.70 and 0.82 eV accomplishing the curve fit analyses method. The peak maximum temperatures and orders of kinetics of each deconvoluted peak were also determined as an outcome of fitting process. TSC experiments were expanded by making the measurements at various heating rates between 0.1 and 0.3 K/s to get information about the heating rate dependent peak parameters.

Design and implementation of an adaptive relay based on curve-fitting technique for micro-grid protection

The micro-grid should operate in a well controlled manner both during grid connected and islanded mode. Also, micro-grid equipped with conventional overcurrent relays has protection issues during faults due to the difference in fault currents when micro-grid operation changes from one mode to the other. This paper proposes suitable relaying scheme based on curve-fitting technique for micro-grids and performs well without using any extensive communication facility. A new algorithm is developed to create large number of fault data for fitting the curve. The fitness of curve is accessed by measuring the value of coefficient R-squared value (R 2). More number of polynomials is added to improve the value of R 2. Results show that the actual tripping time of the relay is very close to desired tripping time by introducing more number of polynomials. Efficiency of the proposed method is evaluated by comparing with conventional over current relay. The protection logic of the curve-fit relay has been implemented on a TMS32F28377S micro-controller based hardware. A laboratory based experimental setup has been established to test the operational performance of curve-fit relay for a five bus system.

The Elephant Problem—Determining Bulk Thermal Diffusivity

This study investigates a measurement method of thermal diffusivity for samples with arbitrary geometries and unknown material properties. The aim is to curve fit the thermal diffusivity with the use of a numerical simulation and transient temperature measurement inside the object of interest. This approach is designed to assess bulk material properties of an object that has a composite material structure such as underground soil. The method creates the boundary conditions necessary to apply analytical theory found in the literature. It was found that measurements best correlated with theory and simulation at positions between the center and surface of an object.

Radio-sensitivity of irradiated seed, plantlets, callus, and in vitro leaves from Indigofera zollingeriana Miq by gamma rays

Test of radio-sensitivity is important to use as a recognizable effect of radiation. The optimal doses usually create maximum variability. Radio-sensitivity of each part of plants of Indigofera zollingeriana Miq to gamma rays had no report yet. This research aimed to know radio-sensitivity, optimal doses, and growth of M1 generation from each material of I. zollingeriana irradiated with gamma rays. Seed, plantlets, callus, and in vitro leaves were tested for radio sensitivity by gamma rays. Doses level used of Gamma rays were: 0 until 500 Gy. The value of LD50 of each material was evaluated using Curve-fit Analysis. Growth parameters from each material were observed for six weeks after planting and analyzed using IBM SPSS 22. Research showed that the sensitivity of each doses level was different for each source of the material plant. The seed had radio-sensitivity of gamma rays at dose 183.988 Gy, plantlet at dose 253.677 Gy, callus could not calculate, and in vitro leaves at dose 242.241 Gy.

A.2 Clinical application of T1-w/T2-w ratio images for in vivo comparisons of myelin content in patients with trigeminal neuralgia

Background: Novel magnetic resonance (MR) imaging techniques prompted the emergence of T1-w/T2-w images or “myelin-sensitive maps (MMs)” to measure myelin in vivo. However, acquisition-related variations in MR intensities prevent meaningful quantitative comparisons between MMs. We propose an improved pipeline to standardize MMs that is applied to patients with classic trigeminal neuralgia (CTN) and trigeminal neuralgia secondary to multiple sclerosis (MSTN). Methods: 3T scanner was used to obtain T1-w and T2-w images for 17 CTN and 17 MSTN patients. Template images were obtained from ICBM152 database. MS plaques and normal-appearing white matter (NAWM) were labelled. A Gaussian curve-fit was applied to the histogram of the intensity distribution of each patient image, and transformed to match the Gaussian curve-fit of the template image. Results: MM intensities were decreased within MS plaques, compared to NAWM in MSTN patients (p<0.001) and its corresponding regions in CTN patients (p<0.001). Qualitatively, the standardized patient image and its histogram better resembled the ICBM152 template. Conclusions: MM analysis revealed reduced myelin content in MS plaques compared to corresponding regions in CTN patients and surrounding NAWM in MSTN patients. The standardized MM serves as a non-invasive, clinical tool for quantitative analyses of myelin content between different brain regions and different patients in vivo.

Start of the Green Season and Normalized Difference Vegetation Index in Alaska’s Arctic National Parks

Daily Normalized Difference Vegetation Index (NDVI) values from the MODIS Aqua and Terra satellites were compared with on-the-ground camera observations at five locations in northern Alaska. Over half of the spring rise in NDVI was due to the transition from the snow-covered landscape to the snow-free surface prior to the deciduous leaf-out. In the fall after the green season, NDVI fluctuated between an intermediate level representing senesced vegetation and lower values representing clouds and intermittent snow, and then dropped to constant low levels after establishment of the permanent winter snow cover. The NDVI value of snow-free surfaces after fall leaf senescence was estimated from multi-year data using a 90th percentile smoothing spline curve fit to a plot of daily NDVI values vs. ordinal date. This curve typically showed a flat region of intermediate NDVI values in the fall that represent cloud- and snow-free days with senesced vegetation. This “fall plateau” was readily identified in a large systematic sample of MODIS NDVI values across the study area, in typical tundra, shrub, and boreal forest environments. The NDVI level of the fall plateau can be extrapolated to the spring rising leg of the annual NDVI curve to approximate the true start of green season.

Mechanical Characterization of Porcine Skin Starting Material

Porcine skin has been used as a starting material in several released mesh medical devices. Although this controlled animal derived material is prevalent in tissue engineered medical devices, little is known about its mechanical properties. This study mechanically characterized Porcine Skin Starting Material (PSSM), provided by Midwest Research Swine. Uniaxial tensile tests were performed on samples cut from different regions (back and neck) and orientations (parallel and perpendicular to the spine) on the PSSM. The stress-stretch relationship was determined for each sample utilizing a load frame equipped with a Digital Image Correlation measurement system. The PSSM skin demonstrates the classic nonlinear and linear regions seen in other biologic tissues. A bilinear curve fit method was used to separate the nonlinear and linear regions of the tensile curve, and each region was analyzed with an Ogden and linear model respectively. The results show that the tensile curve is better described with this method as opposed to analyzing the full curve with one model. A comparison was made between samples cut from the different regions and orientations. There were significant differences between the failure measures and mechanical indices from the two regions, and on average the back behaved anisotropically and the neck isotropically. The PSSM mechanical properties from this study could serve as a preliminary guide for those exploring devices or processes in the tissue engineering field. The methods demonstrated in this study could also help characterize other biologic materials, and be used towards the development of tissue specific industrial standards.

The threshold effect of factors associated with spontaneous abortion in human-assisted reproductive technology

We explored the independent risk factors associated with cases of spontaneous abortion in infertile patients treated with human-assisted reproductive technology (ART) and established a smooth curve fit and perform a threshold effect analysis can provide guidance and a valuable reference for predicting the probability of spontaneous abortion. This was a retrospective cohort study of 16,097 patients successfully conceived with ART in Shangqiu First People's Hospital from June 2013 to December 2018. Overall, 2,378 (14.77%) had an abortion and 13,719 (85.23%) did not have an abortion. Multivariate logistic regression analysis showed that female age (OR 1.050; 95% CI 1.032–1.069; P < 0.001), male age (OR 1.100; 95% CI 1.086–1.115; P < 0.001), follicular-stimulating hormone (OR 1.049; 95% CI 1.022–1.076; P < 0.001), anti-Mullerian hormone (OR 0.893; 95% CI 0.862–0.925; P < 0.001) and the number of fetuses at pregnancy diagnosis were independent factors associated with spontaneous abortion. The threshold effect analysis found that when female age > 32 years (cut-off point) old, age and the risk of spontaneous abortion were positively correlated. When follicular-stimulating hormone > 6.1 IU/L (cut-off point), follicular-stimulating hormone was positively correlated with the occurrence of spontaneous abortion, When anti-Mullerian hormone ≤ 3.1 ng/mL (cut-off point), anti-Mullerian hormone was negatively correlated with the occurrence of spontaneous abortion and there was a linear positive correlation between antral Follicle Counting and live birth. In addition, the older the male age, the higher the incidence of abortion. The smooth curve fit and threshold effect analyses can provide a more detailed estimate of the probability of spontaneous abortion for pregnant couples.

EFEK IRADIASI SINAR GAMMA PADA TANAMAN KACANG PENUTUP TANAH (Mucuna bracteata L.)

Legume cover crop (Mucuna bracteata L.) is a creeper which is currently often used to increase soil fertility in plantation areas. This plant is a leguminous plant that can fix nitrogen nutrients in the soil. One of the M.bracteata plant breeding programs to increase diversity is mutation using gamma ray radiation. The research objective was to determine the level of radiosensitivity of legume cover crop using gamma ray irradiation. The research was conducted at PAIR BATAN using a Gamma Chamber 4000A irradiator and in agricultural experiment, Labuhanbatu University. The plant material used was M.bracteata seeds with irradiation doses of 0, 200, 250, 300, 350 and 400 Gy. This study uses a curve fit analysis program to calculate the LD50 value (Lethal dose 50). The results showed that the plant radiosensitivity by calculating the LD50 value of M.bracteata at the age of 2 Weeks After Planting) was 348.737 Gy. The higher the radiation dose given, the lower the percentage of growth. Key words: diversity; leguminous; lethal dosage; mutation; gamma rays