INVESTIGATION OF LED-BASED COMPACT TRANSFER STANDARD SOURCE FOR LUMINANCE MEASUREMENT

Abstract Autocollimators are versatile devices for angle metrology used in a wide range of applications in engineering and manufacturing. A modern electronic autocollimator generally features two measuring axes and can thus fully determine the surface normal of an optical surface relative to it in space. Until recently, however, the calibration capabilities of the national metrology institutes were limited to plane angles. Although it was possible to calibrate both measuring axes independently of each other, it was not feasible to determine their crosstalk if angular deflections were present in both axes simultaneously. To expand autocollimator calibrations from plane angles to spatial angles, PTB and VTT MIKES have created dedicated calibration devices which are based on different measurement principles and accomplish the task of measurand traceability in different ways. Comparing calibrations of a transfer standard makes it possible to detect systematic measurement errors of the two devices and to evaluate the validity of their uncertainty budgets. The importance of measurand traceability via calibration for a broad spectrum of autocollimator applications is one of the motivating factors behind the creation of both devices and for this comparison of the calibration capabilities of the two national metrology institutes. The latter is the focus of the work presented here.

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Field evaluation of water or citrate soluble phosphorus in modified phosphate rocks for soybean

Scientia Agricola ◽

10.1590/s0103-90162001000100025 ◽

2001 ◽

Vol 58 (1) ◽

pp. 165-170 ◽

Cited By ~ 2

Author(s):

Luís Ignácio Prochnow ◽

José Francisco da Cunha ◽

Ariel Francisco Candiotti Ventimiglia

Keyword(s):

Field Evaluation ◽

Water Soluble ◽

Ammonium Citrate ◽

Low Grade ◽

Triple Superphosphate ◽

Single Superphosphate ◽

Standard Source ◽

Extractable P ◽

P Fertilizers ◽

P Sources

Ten P fertilizers were collected (commercial fertilizers) or synthesized (experimental sources) in order to obtain single superphosphates varying in water and citrate solubility. A standard source of P was also produced by crystallization of the water-soluble fraction of a triple superphosphate. Eleven P sources were band applied to a medium textured Xanthic Hapludox, in Bahia, Brazil (low content of resin-extractable P) at a rate of 80 kg ha-1 of NAC + H2O (neutral ammonium citrate plus water) soluble P2O5, with soybean as the crop which was grown to maturity. A check plot (control) was included in the study. Three of the P sources [single superphosphate produced from Araxa phosphate rock (PR), low-grade single superphosphate produced from Lagamar PR and the standard source of P] were also applied at rates to provide 40 and 120 kg ha-1 of NAC + H2O soluble P2O5. Yield of soybean was evaluated by analysis of variance with mean comparison performed utilizing LSD lines, considering the P sources applied at a rate of 80 kg ha-1 of P2O5 + control. Regression procedures were used to study the relation between yield of soybean and rates of P2O5. The fertilizers tested performed equally well as a source of P for soybean. The level of water-soluble P did not influence fertilizer performance.

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standard source

Computer Science and Communications Dictionary ◽

10.1007/1-4020-0613-6_18082 ◽

2000 ◽

pp. 1651-1651

Author(s):

Martin H. Weik

Keyword(s):

Standard Source

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