scholarly journals Over-volted breakdown and recovery of short nitrogen spark gaps

2010 ◽  
Vol 28 (3) ◽  
pp. 443-450 ◽  
Author(s):  
Xinjing Cai ◽  
Xiaobin Zou ◽  
Xinxin Wang ◽  
Liming Wang ◽  
Zhicheng Guan ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Breakdown Voltage ◽  
Gaussian Distribution ◽  
Recovery Time ◽  
Time Dependent ◽  
Experimental Conditions ◽  
Pulse Technique ◽  
Residual Nitrogen ◽  
Spark Gap ◽  
Gap Spacing

AbstractThe characteristic of the over-volted breakdown and the gaseous recovery in short nitrogen gaps was experimentally studied. It was found that the breakdown voltage of the gap changes from shot to shot even with the same experimental conditions and obeys Gaussian distribution. The over-volted factor is reduced with an increasing pressure. With a 2.7-mm gap the over-volted factors are 4.53 for 0.1 MPa pressure and 1.74 for 0.4 MPa. The over-volted breakdown voltage depends individually on the gap spacing d and the gas pressure p, rather than on the product of pd. An empirical formula of the breakdown voltage as a function of p and d was derived. The time-dependent recovery of the breakdown voltage, RVb, was obtained using a two-pulse technique. The second breakdown voltage also obeys Gaussian distribution, but it is normally with a smaller standard deviation especially when the interpulse spacing of Δt is relatively short. As a whole, RVb rises with the increase of Δt. However, an intermediate plateau is always observed and it starts when the second breakdown voltage is a little bit higher than the static breakdown voltage of the gap. The first rising edge of the RVb curve corresponds to the recovery of the electro-neutrality and the density. The intermediate plateau and the following rising edge take the spark gap much longer time to recover. The processes governing these two latter phases are as yet not fully clear. It is attributed to the delayed recombination of the residual nitrogen atoms on the cathode to produce the initial electrons for the second breakdown. An increase in pressure has resulted in an upward shift of the intermediate plateau and a shortening in the recovery time of the gaps. The second spark generally does not follow the path of the first spark.

Evidence for time-dependent autonomic cardiac reinnervation in children subsequent to transplantation of the heart

1996 ◽  
Vol 6 (1) ◽  
pp. 12-19
Author(s):  
Joachim Kreuder ◽  
Heinrich Netz ◽  
Thomas Paul ◽  
Andreas Müller ◽  
Jürgen Bauer ◽  
...  
Keyword(s):  
Heart Rate ◽  
Standard Deviation ◽  
Time Domain ◽  
Recovery Time ◽  
Cardiac Transplantation ◽  
Sinus Node ◽  
Time Dependent ◽  
Rr Intervals ◽  
The Mean ◽  
Frequency Power

AbstractAutonomic denervation has been assumed to persist after orthotopic heart transplantation. Analyzing spontaneous and induced variations of heart rate, the status of autonomic cardiac innervation was investigated in six children 19–37 months after cardiac transplantation. The age at the time of transplantation varied from three weeks to 15.4 years. Heart rate variability was assessed on 24-hour Holter recordings by calculating time-domain indices (standard deviation of all RR intervals; standard deviation of the mean RR intervals from successive five-minute periods; mean of the standard deviations of RR intervals from successive five-minute periods; proportion of adjacent RR intervals > 50 msec different; square root of mean square successive differences in RR intervals) and frequency-domain variables (low frequency power, high frequency power and total spectrum power). Sinus node recovery time, sinoatrial conduction time and post-pacing cycle lengths were examined at different rates of endocardial atrial pacing. After the first year subsequent to transplantation, standard deviation of the mean RR intervals reached the normal range in four patients, whereas the other time-domain variables became normal in two patients. Both patients displayed normal or near-normal power spectrums of heart rate with normal day-to-night variations. For the remaining patients, spectrums of heart rate failed to show the main frequency peaks. Only the patient with normal variability in heart rate exhibited a decrease in corrected sinus node recovery time at higher stimulation rates, shortening of the first recovery cycle below the pre-pacing level, and a rapid decline of the accelerated post-pacing heart rate as described in innervated hearts. These results suggest the evolution of time-dependent efferent autonomic reinnervation after cardiac transplantation in children.

Determination of alcohols in mixtures by 19F NMR spectroscopy using hexefluoroacetone reagent

1982 ◽  
Vol 47 (7) ◽  
pp. 1973-1978 ◽  
Author(s):  
Jiří Karhan ◽  
Zbyněk Ksandr ◽  
Jiřina Vlková ◽  
Věra Špatná
Keyword(s):  
Standard Deviation ◽  
Nmr Spectroscopy ◽  
Standard Method ◽  
Internal Standard ◽  
Internal Standard Method ◽  
Concentration Region ◽  
Experimental Conditions ◽  
Curve Method ◽  
Sample Preparation Procedure

The determination of alcohols by 19F NMR spectroscopy making use of their reaction with hexafluoroacetone giving rise to hemiacetals was studied on butanols. The calibration curve method and the internal standard method were used and the results were mutually compared. The effects of some experimental conditions, viz. the sample preparation procedure, concentration, spectrometer setting, and electronic integration, were investigated; the conditions, particularly the concentrations, proved to have a statistically significant effect on the results of determination. For the internal standard method, the standard deviation was 0.061 in the concentration region 0.032-0.74 mol l-1. The method was applied to a determination of alcohols in the distillation residue from an oxo synthesis.

scholarly journals A kinetic method for the determination of phenol

2002 ◽  
Vol 67 (10) ◽  
pp. 661-667 ◽  
Author(s):  
Snezana Mitic ◽  
Valentina Zivanovic
Keyword(s):  
Standard Deviation ◽  
River Water ◽  
Reaction Rate ◽  
Kinetic Method ◽  
Potassium Periodate ◽  
Experimental Conditions ◽  
Inhibiting Effect ◽  
Relative Standard ◽  
Kinetic Expression

Akinetic method for the determination of phenol is proposed. The method is based on the inhibiting effect of phenol on the Mn(II) catalysis of the oxidation of malachite green with potassium periodate. The reaction rate was followed spectrophotometrically at 615 nm. Kinetic expression for the reaction in the presence and absence of phenol are postulated. The optimal experimental conditions for the determination of phenol were established and phenol was determined in concentrations from 30.0 to 188.0 ng/cm3 with a relative standard deviation of 5.5%. The lower detecton limit is 7.8 ng/cm3. The effects of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. The method was applied for the determination of phenol in tap and river water.

A model for the effect of bias for cholesterol on the population at risk.

1988 ◽  
Vol 34 (11) ◽  
pp. 2256-2259 ◽  
Author(s):  
M H Kroll ◽  
M Ruddel ◽  
R J Elin
Keyword(s):  
At Risk ◽  
Standard Deviation ◽  
Reference Values ◽  
Gaussian Distribution ◽  
Population Distribution ◽  
Reference Value ◽  
Mean Value ◽  
The Body ◽  
Methodological Bias ◽  
The Mean

Abstract The location of the Reference Value for an analyte within the population distribution affects the magnitude of error due to methodological bias. Using the gaussian distribution, we evaluated the effects of systematic and proportional biases of the method (positive and negative), mean value, and standard deviation on the magnitude of error. We chose four Reference Values for cholesterol as a model. For a population with a mean of 2.0 and SD of 0.36 g of cholesterol per liter, a 3% positive proportional bias causes sixfold more error at the 50th percentile than at the 97.5th. In general, the error for a given bias (proportional or systematic) is greater for a Reference Value within the body than at the tails of the distribution. Further, the magnitude of the error varies as a function of the mean and standard deviation of the population.

scholarly journals Metrology of a Focusing Capillary Using Optical Ptychography

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6462
Author(s):  
Xiaojing Huang ◽  
Evgeny Nazaretski ◽  
Weihe Xu ◽  
Dean Hidas ◽  
Mark Cordier ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Laser Beam ◽  
Gaussian Distribution ◽  
Capillary Surface ◽  
Functional Surfaces ◽  
Phase Profile ◽  
Reflective Optics ◽  
Focusing Property ◽  
Focused Beam ◽  
Quantitative Tool

The focusing property of an ellipsoidal monocapillary has been characterized using the ptychography method with a 405 nm laser beam. The recovered wavefront gives a 12.5×10.4μm2 focus. The reconstructed phase profile of the focused beam can be used to estimate the height error of the capillary surface. The obtained height error shows a Gaussian distribution with a standard deviation of 1.3 μm. This approach can be used as a quantitative tool for evaluating the inner functional surfaces of reflective optics, complementary to conventional metrology methods.

Comparative DFT study for molecular geometries and spectra of methyl pheophorbides-a: test of M06-2X and two other functionals

2010 ◽  
Vol 14 (07) ◽  
pp. 592-604 ◽  
Author(s):  
Do Sung Huh ◽  
Sang Joon Choe
Keyword(s):  
Density Functional Theory ◽  
Standard Deviation ◽  
Density Functional ◽  
Visible Spectrum ◽  
Mean Value ◽  
Time Dependent ◽  
Dft Methods ◽  
Functional Theory ◽  
Td Dft ◽  
The Mean

The recent interest in the application of density functional theory (DFT) has prompted us to test several functions in molecular geometries of methyl pheophorbides-a (MPa), an important starting material in photodynamic therapy (PDT). In this study, we report on tests for three popular DFT methods: M06-2X, B3LYP, and LSDA. Based on the standard deviation and the mean value, and by using the difference between optimized calculated value and experimental value in geometries, we drew the following conclusions: M06-2X/6-311+G(d,p) attained the smallest standard deviation of difference among the tested DFT methods in terms of bond length, whereas the standard deviation of bond angle in LSDA/6-311+G(d,p) was the smallest. In terms of absolute value, the mean value of LSDA/6-311+G(d,p) calculation was larger than that of M06-2X/6-311+G(d,p). We found that M06-2X/6-311+G(d,p) gave the best performance for MPa in the molecular geometries. The UV-visible spectrum was calculated with time-dependent density-functional theory (TD-DFT). Time-dependent M06-2X/6-311+G(d,p) gave the best performance for MPa in CH2Cl2 solution. In general, TD-DFT calculations in CH2Cl2 solution were more red-shifted compared with those in the solid state.

scholarly journals Comparative Performance of Catalytic Fenton Oxidation with Zero-Valent Iron (Fe(0)) in Comparison with Ferrous Sulphate for the Removal of Micropollutants

2019 ◽  
Vol 9 (11) ◽  
pp. 2181
Author(s):  
Anuradha Goswami ◽  
Jia-Qian Jiang
Keyword(s):  
Standard Deviation ◽  
Signal To Noise Ratio ◽  
Ferrous Sulphate ◽  
Fenton Oxidation ◽  
Zero Valent Iron ◽  
Fenton Process ◽  
Signal To Noise ◽  
Experimental Conditions ◽  
Comparative Performance ◽  
Sludge Production

This research aims to depict the comparative performance of micropollutants’ removal by FeSO4- and zero-valent iron (Fe(0))-catalytic Fenton oxidation and to explore the possibilities of minimising the sludge production from the process. The emerging micropollutants used for the study were gabapentin, sulfamethoxazole, diuron, terbutryn and terbuthylazine. The Taguchi method, which evaluates the signal-to-noise ratio instead of the standard deviation, was used to develop robust experimental conditions. Though both FeSO4- and Fe(0)-catalytic Fenton oxidation were able to completely degrade the stated micropollutants, the Fe(0)-catalytic Fenton process delivered better removal of dissolved organic carbon (DOC; 70%) than FeSO4 catalytic Fenton oxidation (45%). Fe(0)-catalytic Fenton oxidation facilitated heterogeneous treatment functions, which eliminated toxicity from contaminated solution and there was no recognisable sludge production.

scholarly journals Computations of Unsteady Multistage Compressor Flows in a Workstation Environment

1991 ◽  
Author(s):  
Karen L. Gundy-Burlet
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Standard Deviation ◽  
Unsteady Flow ◽  
Computing Time ◽  
Floating Point ◽  
Computational Fluid Dynamics Cfd ◽  
Multistage Compressor ◽  
Gap Spacing

High-end graphics workstations are becoming a necessary tool in the Computational Fluid Dynamics (CFD) environment. In addition to their graphics capabilities, the latest generation of workstations have powerful floating point operation capabilities. As workstations become common, they could provide valuable computing time for applications, such as turbomachinery flow calculations. This paper discusses the issues involved in implementing an unsteady, viscous multistage turbomachinery code (STAGE-2) on workstations. The workstation version of STAGE-2 has then been used to study the effects of axial-gap spacing on the time-averaged and unsteady flow within a 2 1/2-stage compressor. Results include force polar plots, time-averaged pressure contours, standard deviation of pressure contours, time-averaged surface pressures and pressure amplitudes.

scholarly journals Detection of the Strains Induced in Murine Tibias by Ex Vivo Uniaxial Loading with Different Sensors

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5109
Author(s):  
Emanuele Rizzuto ◽  
Barbara Peruzzi ◽  
Mariagrazia Giudice ◽  
Enrica Urciuoli ◽  
Erika Pittella ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ex Vivo ◽  
Mean Value ◽  
Uniaxial Loading ◽  
Image Correlation ◽  
Strain Gauges ◽  
Experimental Conditions ◽  
The Mean

In this paper, the characterization of the main techniques and transducers employed to measure local and global strains induced by uniaxial loading of murine tibiae is presented. Micro strain gauges and digital image correlation (DIC) were tested to measure local strains, while a moving coil motor-based length transducer was employed to measure relative global shortening. Local strain is the crucial parameter to be measured when dealing with bone cell mechanotransduction, so we characterized these techniques in the experimental conditions known to activate cell mechanosensing in vivo. The experimental tests were performed using tibia samples excised from twenty-two C57BL/6 mice. To evaluate measurement repeatability we computed the standard deviation of ten repetitive compressions to the mean value. This value was lower than 3% for micro strain gauges, and in the range of 7%–10% for DIC and the length transducer. The coefficient of variation, i.e., the standard deviation to the mean value, was about 35% for strain gauges and the length transducer, and about 40% for DIC. These results provided a comprehensive characterization of three methodologies for local and global bone strain measurement, suggesting a possible field of application on the basis of their advantages and limitations.

A Study on Gadolinium Sensitized Chemiluminescence System

2012 ◽  
Vol 535-537 ◽  
pp. 1337-1340 ◽  
Author(s):  
Chi Yang ◽  
Nai Lin Ren
Keyword(s):  
Standard Deviation ◽  
Detection Limit ◽  
Linear Relationship ◽  
Relative Standard Deviation ◽  
Optimum Conditions ◽  
Chemiluminescence Intensity ◽  
Experimental Conditions ◽  
Relative Standard

A new chemiluminescence system was built by using gadolinium as sensitizer, and the analysis capabilities of this system was tested as below. The method is based on chemluminescence of Ce (IV)-SO32- sensitized by Gd3+-OFLX. The effects of some critical experimental conditions were discussed and the optimum conditions for chemluminescence emission were investigated. The linear relationship between the relative chemiluminescence intensity and the concentration of OFLX is in the range of 2×10-9 g/mL～5×10-7 g/mL with a detection limit of 1.0×10-9g/mL .The relative standard deviation is 2.8% (n=11) for a level of 5.0×10-7 g/mL. The method has been applied to the analysis of OFLX in tablets with satisfactory results.

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