scholarly journals National Physical Laboratory Radiocarbon Measurements II

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 25-30 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
Daphne H. Pritchard
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Research Programme ◽  
National Physical Laboratory ◽  
Reference Standard ◽  
Best Value ◽  
Physical Laboratory ◽  
The Difference ◽  
Absolute Age

The following list comprises measurements made since those reported in NPL I and is complete to the end of November 1963.Ages are relative to a.d. 1950 and are calculated using a half-life of 5568 yr. The measurements have been corrected for fractionation and referred to 0.950 times the activity of the NBS oxalic acid as a contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances, viz. those of the standard and background measurements over a rolling twenty-week period, of the sample measurements from at least three independent fillings, of the δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty included. If the net sample activity is less than 4 times the standard error of the difference between the sample and background activities, a lower limit to the age is reported equivalent to a sample activity of 4 times the standard error of this difference.The description of each sample is based on information provided by the person submitting the sample to the Laboratory.The work reported forms part of the research programme of the Laboratory and is published by permission of the Director.

scholarly journals National Physical Laboratory Radiocarbon Measurements IV

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 340-347 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
Geraldine I. Hassall
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Count Rate ◽  
National Physical Laboratory ◽  
Background Count ◽  
Best Value ◽  
Sample Count ◽  
The Difference ◽  
Absolute Age

The following list comprises measurements made since those reported in NPL III and is complete to the end of November 1965.Ages are relative to A.D. 1950 and are calculated using a half-life of 5568 yr. The measurements, corrected for fractionation (quoted δC13 values are relative to the P.D.B. standard), are referred to 0.950 times the activity of the NBS oxalic acid as contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances as described in detail in NPL III. These variances are those of the standard and background measurements over a rolling twenty week period, of the sample δC14 and δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty then included. If the net sample count rate is less than 4 times the standard error of the difference between the sample and background count rates, a lower limit to the age is reported corresponding to a net sample count rate of 4 times the standard error of this difference.

Development of a High Temperature Interconnect Solution as an Alternative to High Lead or Gold Content Solders

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000196-000206
Author(s):  
Martin Wickham ◽  
Kate Clayton ◽  
Ana Robador ◽  
Chris Hunt ◽  
Robin Pittson ◽  
...  
Keyword(s):  
High Temperature ◽  
Electronic Materials ◽  
Research Programme ◽  
National Physical Laboratory ◽  
Electrical Performance ◽  
Processing Temperature ◽  
Gold Content ◽  
Physical Laboratory ◽  
Electronic Assemblies ◽  
High Lead

AbstractA collaborative research programme between project partners Microsemi, the National Physical Laboratory (NPL) and Gwent Electronic Materials (GEM), has successfully developed innovative materials specifically designed to offer an alternative for high Pb or Au content materials to increase the operating temperature of electronic assemblies. Currently, for electronic assemblies to operate at high temperature, they must use a high lead solder or a very expensive gold based solder to withstand these temperatures. The ELCOSINT project has developed an inexpensive lead-free alternative for joining high temperature electronics suitable for operating at temperatures above 250°C utilising standard surface mount assembly processes. This paper summarises the work undertaken by the authors to develop and better understand this new family of electrical interconnection materials. The project brought together a materials supplier (GEM – Gwent Electronic Materials), an end-user (MSL - Microsemi) and an technology research organisation (NPL – National Physical Laboratory) to jointly develop, test and implement in production, the solution based on silver-loaded silicone materials. This paper focuses on the testing and materials evaluation undertaken at NPL to determine the long term performance of these alternative materials including high temperature ageing up to 300°C, thermal cycling and damp heat testing. Details of the shear strength and electrical performance of interconnects between the substrates and components during the test regimes are given. The manufacturing process is outlined including details of the test vehicles utilised. The processing temperature for the conductive adhesive is 250°C which offers additional advantages in potential improvements in component and substrate reliability compared to soldered solutions which would typically be processed at temperatures above 300°C.

scholarly journals Reliable Change Formula Query: Temkin et al. reply

2000 ◽  
Vol 6 (3) ◽  
pp. 364-364 ◽  
Author(s):  
NANCY R. TEMKIN ◽  
ROBERT K. HEATON ◽  
IGOR GRANT ◽  
SUREYYA S. DIKMEN
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Direct Method ◽  
Single Point ◽  
Reliability Coefficient ◽  
Reliable Change Index ◽  
Square Root ◽  
Reliable Change ◽  
The Difference ◽  
The One

Hinton-Bayre (2000) raises a point that may occur to many readers who are familiar with the Reliable Change Index (RCI). In our previous paper comparing four models for detecting significant change in neuropsychological performance (Temkin et al., 1999), we used a formula for calculating Sdiff, the measure of variability for the test–retest difference, that differs from the one Hinton-Bayre has seen employed in other studies of the RCI. In fact, there are two ways of calculating Sdiff—a direct method and an approximate method. As stated by Jacobson and Truax (1991, p. 14), the direct method is to compute “the standard error of the difference between the two test scores” or equivalently [begin square root](s12 + s22 − 2s1s2rxx′)[end square root] where si is the standard deviation at time i and rxx′ is the test–retest correlation or reliability coefficient. Jacobson and Truax also provide a formula for the approximation of Sdiff when one does not have access to retest data on the population of interest, but does have a test–retest reliability coefficient and an estimate of the cross-sectional standard deviation, i.e., the standard deviation at a single point in time. This approximation assumes that the standard deviations at Time 1 and Time 2 are equal, which may be close to true in many cases. Since we had the longitudinal data to directly calculate the standard error of the difference between scores at Time 1 and Time 2, we used the direct method. Which method is preferable? When the needed data are available, it is the one we used.

scholarly journals The Effectiveness of Mix Impact Aerobic Gymnastics Exercises With SKJ 2000 On Improvement of Physical Freshness

2021 ◽  
Vol 12 (03) ◽  
pp. 39-44
Author(s):  
Anik Maryani ◽  
Fahmy Fachrezzy ◽  
Ramdan Pelana
Keyword(s):  
Standard Deviation ◽  
Physical Fitness ◽  
Aerobic Exercise ◽  
Standard Error ◽  
Exercise Group ◽  
Mean Value ◽  
Mean Difference ◽  
Final Test ◽  
The Mean ◽  
The Difference

This study aims to determine the effectiveness of the effect of aerobic mix impact and SKJ 2000 version (core exercise) to improve physical fitness in female students. The research was conducted at SMEA YASMA Sudirman Cijantung for 8 weeks with 24 meetings. The method used is an experimental method with a pre and post-test design. The sampling technique was random sampling from a total of 40 grade 1 students and 30 samples were taken. The data collection technique used was a physical fitness test using the Indonesian Physical Fitness Test (TKJI). Hypothesis testing uses the t-test at the significant level (α) 0.05. The results showed that the difference between the mean value of the initial test (x) and the final test (y) in the mixed impact aerobic exercise group was obtained = -6.47; the value of the standard deviation of the difference = 1,2; the standard error value of the mean difference = 0.32; and the value becomes = -20,2. The initial test (x) and the final test (y) in the 2000 version of the Physical Fitness exercise obtained the difference in the mean value is = -5; the value of the standard deviation of the difference = 1.1; the standard error value of the mean difference = 0.29; and the value becomes = -17.24. The final test of the mixed impact aerobic exercise group (x) and the final test of the aerobic exercise group (y) version 2000, obtained the mean value of the variable x = 19.33; variable value y = 17; the standard deviation value x = 1.48; standard deviation of the variable y = 2.31; standard error variable x = 0.4; standard error for the variable y = 0.62; standard error for the mean difference between x and variable = 0.74; Hypothesis test results obtained t observation = 3.15, at 28 degrees of freedom and a significant level (α) 0.05, the value of t table = 2.048 is obtained. The conclusion of the study is that the effect of mix impact aerobic exercise is more effective in improving physical fitness compared to those using the 2000 version of the fitness gymnastics version of aerobic exercise.

scholarly journals National Physical Laboratory Radiocarbon Measurements I

Radiocarbon ◽  
1963 ◽  
Vol 5 ◽  
pp. 34-38 ◽  
Author(s):  
W. J. Callow ◽  
M. J. Baker ◽  
D. H. Pritchard
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
National Physical Laboratory ◽  
Boric Oxide ◽  
Paraffin Wax ◽  
Absolute Pressure ◽  
Constant Density ◽  
Reference Standard ◽  
Physical Laboratory ◽  
Oak Tree

The dating equipment at the National Physical Laboratory was completed by the summer of 1960. A series of calibration and intercomparison measurements was undertaken however, using the NBS oxalic acid reference standard, a modern wood standard (1850 oak tree) and other material before starting routine measurements toward the end of 1961. All results have been obtained using a 4.5 L copper proportional counter filled with CO2 at a constant density corresponding to standard conditions of 22°C and an absolute pressure of 150 cm Hg. The counter is shielded by 8 in. of steel, 6 in. of paraffin wax containing boric oxide, 23 Geiger counters arranged as two independent groups and finally by 1 in. of mercury.

scholarly journals Institute of Geological Sciences Radiocarbon Dates II

Radiocarbon ◽  
1972 ◽  
Vol 14 (1) ◽  
pp. 140-144 ◽  
Author(s):  
E. Welin ◽  
L. Engstrand ◽  
S. Vaczy
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Half Life ◽  
Radiocarbon Dates ◽  
Geological Sciences

This date list was compiled by the Institute of Geological Sciences (U.K.) incorporating data supplied under contract by E. Welin, Radioactive Dating Laboratory, Stockholm. Unless otherwise stated, age figures are in C14 years before A.D. 1950. The half-life of C14 is taken as 5568 and the standard error is given as a standard deviation of 1σ. Correction for C13/C12 has not been made.

AN IMPROVED INTERFEROMETER FOR DETERMINING PARALLELISM ERRORS IN LONG END-GAUGES

1947 ◽  
Vol 25f (3) ◽  
pp. 242-259
Author(s):  
L. Graham Turnbull
Keyword(s):  
Mechanical Design ◽  
National Physical Laboratory ◽  
Physical Laboratory ◽  
Specialized Technique ◽  
End Gauges ◽  
The Difference

This paper describes an interferometer designed for the determination of the parallelism of the working faces of end-gauges up to 24 in. in length. An instrument for this purpose, but which required somewhat highly specialized technique in the course of its construction, had been previously designed by the National Physical Laboratory. Using optical principles the same as those of the British instrument, another of an entirely new mechanical design has been constructed by the National Research Laboratories, Ottawa. This new interferometer incorporates kinematic principles and a number of interesting features to permit easy adjustment and operation to the very fine limits necessary. By the addition of a sensitive level vial to this instrument, the difference in length of nominally equal end-gauges can be determined to an accuracy of 1 or 2 × 10−6 in.

scholarly journals Model for Predicting and Analyzing the %Fe Removed as Deleterious Element from Al-Si alloys During Fe Removal Processing with Mn

2016 ◽  
Vol 2 (6) ◽  
pp. 125
Author(s):  
F. A. Anene ◽  
N. E. Nwankwo
Keyword(s):  
Standard Deviation ◽  
Standard Error ◽  
Model Equation ◽  
Processing Parameters ◽  
Holding Time ◽  
Experimental Result ◽  
Close Proximity ◽  
Mn Content ◽  
The Difference ◽  
Cubic Function

Model equation for predicting and analysing %Fe removed from a eutectic Al-Si alloy during Fe removal processing with Mn under controlled conditions has been derived and validated. The model derived;%Fe removed = +1.30700 + 0.095882* Al-Si + %Mn - 0.068512* Al-Si + %Mn^2 + 9.77000E-003* Al-Si+%Mn^3 ,is found to predict the %Fe removed from Al-Si alloy as a cubic function of Mn content. With a standard deviation of 0.010. Analysed results obtained show that %Fe removal equation with Mn addition has been validly derived. The model " R-Squared" of 0.9814 is found to be in agreement with the "Adj R-Squared" of 0.9628; the difference being less than 0.2. The derived model equation gives a reasonable forecast of %Fe removed very close to the values obtained from the experiments. The close proximity of both model and experimental result values is attributed to the low standard error of the model coefficients. The processing parameters are process temperature, alloy contents and holding time.

scholarly journals Comparison of the Board of Trade ampere-standard balance with the Ayrton-Jones current-weigher; with an appendix on the electromotive forces of standard cells

1908 ◽  
Vol 80 (540) ◽  
pp. 383-389 ◽  
Keyword(s):  
Technical College ◽  
National Physical Laboratory ◽  
Current Strength ◽  
Physical Laboratory ◽  
The Difference ◽  
Set Up ◽  
High Degree ◽  
A Current ◽  
Fair Degree

When the Board of Trade ampere balance was set up and verified in 1894, the platinum weight (marked A) used with the instrument was adjusted so that a current which deposited silver from a 15-per-cent. solution of silver nitrate at the rate of 1·118 milligrammes per second produced, on reversal, a change of force equal to the weight of A. At that period such a current was believed to represent the ampere , viz., 1/10 of a C. G. S. unit, with a fair degree of accuracy. During the last few years a new current weigher, designed at the Central Technical College, has been constructed at the National Physical Laboratory with a precision previously not obtained in any instrument for the absolute determination of current strength, and by means of it the electrochemical equivalent of silver has been determined to a very high degree of accuracy. We therefore considered it of interest to determine the difference between the units of current as measured by the two balances, and at the same time ascertain how nearly the ampere, as measured by the Board of Trade balance, deposits silver at the rate of 1·118 milligrammes per second.

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