A method to measure the spectral responsivity of a photometer using optical excitations with arbitrary spectral distributions

2021 ◽  
pp. 147715352110263
Author(s):  
Christophe Martinsons ◽  
Raed Hlayhel
Keyword(s):  
Inverse Problem ◽  
Probabilistic Approach ◽  
Bayes Theorem ◽  
Spectral Responsivity ◽  
Numerical Application ◽  
Spectral Distributions ◽  
Optical Excitations ◽  
Set Up ◽  
Uncertainty Level ◽  
Good Agreement

The spectral responsivity of a photometer is usually measured using very narrow optical excitations, provided by a monochromator or a tuneable laser. This article describes a technique to measure the spectral responsivity using an arbitrary number of optical excitations having any type of spectral distribution. The problem is formulated as an inverse problem which is solved using a probabilistic approach based on Bayes’ theorem. The method requires a prior knowledge of the spectral responsivity, which can be proportional to the standard photopic function, with an uncertainty level related to the spectral match index of the photometer. Using this method, the estimation can be performed from data provided by a simple experimental set-up. The numerical application provides a stable and unique solution to the inverse problem, along with the estimation uncertainties. Using a tuneable LED source, the method was applied to an illuminance measurement head, giving an estimation of its spectral responsivity from 380 to 780 nm with a step of 1 nm. The results were in good agreement with data obtained by a monochromator-based technique. Our measurement had larger uncertainties towards the red and blue limits of the spectrum as the light source provided very little light at these wavelengths.

scholarly journals Laboratory Measurements of Light Scattering by Dust Particles

1996 ◽  
Vol 150 ◽  
pp. 409-413
Author(s):  
Patrick P. Combet ◽  
Philippe L. Lamy
Keyword(s):  
Light Scattering ◽  
Laser Beam ◽  
Mie Theory ◽  
Spherical Particles ◽  
Dust Particles ◽  
Laboratory Measurements ◽  
Scattering Function ◽  
Hene Laser ◽  
Set Up ◽  
Good Agreement

AbstractWe have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.

The Reduction of Bias Error in Transfer Function Estimates Using FFT-Based Analyzers

1984 ◽  
Vol 106 (1) ◽  
pp. 29-35 ◽  
Author(s):  
P. Cawley
Keyword(s):  
Transfer Function ◽  
Random Excitation ◽  
Analogue Computer ◽  
Bias Error ◽  
Testing Time ◽  
Theoretical Predictions ◽  
Set Up ◽  
Modal Mass ◽  
Time Required ◽  
Good Agreement

The susceptibility to bias error of two methods for computing transfer (frequency response) functions from spectra produced by FFT-based analyzers using random excitation has been investigated. Results from tests with an FFT analyzer on a single degree-of-freedom system set up on an analogue computer show good agreement with the theoretical predictions. It has been shown that, around resonance, the bias error in the transfer function estimate H2 (Syy/Sxy*) is considerably less than that in the more commonly used estimate, H1 (Sxy/Sxx). The record length, and hence the testing time, required for a given accuracy is reduced by over 50 percent if the H2 calculation procedure is used. The analysis has also shown that if shaker excitation is used on lightly damped structures with low modal mass, it is important to minimize the mass of the force gage and the moving element of the shaker.

Simulating the behaviour of folded cartons during complex packing operations

2006 ◽  
Vol 220 (12) ◽  
pp. 1797-1811 ◽  
Author(s):  
D M Sirkett ◽  
B J Hicks ◽  
C Berry ◽  
G Mullineux ◽  
A J Medland
Keyword(s):  
End Users ◽  
Fundamental Issue ◽  
Trial And Error ◽  
Machine Material ◽  
Packaging Machine ◽  
Set Up ◽  
Fine Tune ◽  
Responsiveness To Change ◽  
Lower Production ◽  
Good Agreement

The folding carton is a widely used packaging solution. Recent European Union packaging legislation has forced carton manufacturers to use lighter-weight grades of carton board. This typically results in a reduction in board stiffness, which can lead to decreased process efficacy or even prevent successful processing. In order to overcome this, end-users lower production rates and fine-tune packaging machine settings for each pack and material. This trial-and-error approach is necessary because the rules relating machine set-up to pack design and material properties are not generally well known. The present study addresses this fundamental issue through the creation of a finite-element computer simulation of carton processing. Mechanical testing was performed to ascertain the key mechanical properties of the carton walls and creases. The carton model was validated against the experimental results and was then subjected to the machine-material interactions that take place during complex packaging operations. The overall approach was validated and the simulation showed good agreement with the physical system. The results of the simulation can be used to determine guidelines relating machine set-up criteria to carton properties. This will improve responsiveness to change and will ultimately allow end-users to process thinner lighter-weight materials more effectively.

Numerical Simulation of Compressive Residual Strength for Damaged Composite Laminates

2012 ◽  
Vol 525-526 ◽  
pp. 385-388
Author(s):  
Tian Jiao Qu ◽  
Xi Tao Zheng ◽  
Di Zhang
Keyword(s):  
Composite Laminates ◽  
Impact Test ◽  
Compressive Load ◽  
Low Velocity Impact ◽  
Fiber Breakage ◽  
Low Velocity ◽  
Appearance Time ◽  
Finite Element Software ◽  
Set Up ◽  
Good Agreement

After the low-velocity impact test of composite laminates of T800/BA9916, CAI test and compression test of laminates with a hole have been carried out. Two types of models were set up by the finite element software ABAQUS respectively. The FEA results were good agreement with the testing results. The investigation of models with a hole indicates that the appearance time of ultimate compressive load is earlier than that of fiber breakage expanding to boundary. Moreover, the diameter and the depth of blind hole significantly influence the ultimate compressive load.

scholarly journals Inter-comparison exercise utilizing x- and γ-ray spectrometry

2020 ◽  
Vol 27 ◽  
pp. 121
Author(s):  
Filothei K. Pappa ◽  
Christos Tsabaris ◽  
Dionisis Patiris ◽  
Georgios Eleftheriou ◽  
Effrossini G. Androulakaki ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Natural Radionuclides ◽  
Atomic Spectrometry ◽  
Gamma Ray Spectrometry ◽  
Metal Concentrations ◽  
Activity Concentrations ◽  
Great Divergence ◽  
Set Up ◽  
Comparison Exercise ◽  
Good Agreement

Radionuclides are characterized by their nuclear and chemical behavior. Additionally, the geochemical characteristics of radionuclides result in their accumulation in the sediments via sorption processes. In this work the radionuclide activity concentrations obtained by gamma-ray spectrometry (HPGe detector) were converted to metal concentrations as described in [1]. The results were compared with the measured metal concentrations obtained by atomic spectrometry (X-ray fluorescence system-XRF). The samples originate from the coastal environment of two Greek areas, characterized by elevated values of natural radionuclides (e.g. 226Ra) and metals. The preliminary study revealed a good agreement among the concentrations of potassium calculated via activity concentrations of 40K and those of XRF measurement, while a great divergence was observed for the thorium case. These differences can be attributed to the low statistics, as well as to the calibration set-up of Th XRF measurement.

Conformational Structure of Chloromethyldichlorophosphines

2002 ◽  
Vol 57 (6-7) ◽  
pp. 333-336
Author(s):  
Evgenii A. Romanenko ◽  
Alexander M. Nesterenko
Keyword(s):  
Experimental Data ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Basis Set ◽  
Conformational Structure ◽  
Gauche Conformation ◽  
Nuclear Quadrupole ◽  
Set Up ◽  
Good Agreement

IThe 35Cl nuclear quadrupole resonances (77 K) and ab initio calculations of trichloromethyldichlorophosphine () show that it exists in the chess conformation form. The barrier to internal rotation about the P-C bond in I at the RHF/6-31++ G(d,p) level equals to 38.1 kJ mol-1. In chloromethyldichlorophosphine (II) the extension of the basis set up to the RHF/6-311++G(df, pd) level does not improve the description of the most preferable gauche-conformation; only if electron correlation (at the MP2 level) is taken into account the results are in a good agreement with experimental data.

Dynamic analysis of planar elastic mechanisms using the dyad method

2003 ◽  
Vol 217 (1) ◽  
pp. 1-14 ◽  
Author(s):  
L Romdhane ◽  
H Dhuibi ◽  
H Bel Hadj Salah
Keyword(s):  
Class Ii ◽  
Graph Representation ◽  
Elastic Mechanism ◽  
Complete Automation ◽  
Newton Raphson ◽  
Set Up ◽  
Dyad Analysis ◽  
Planar Linkages ◽  
Raphson Method ◽  
Good Agreement

Based on graph representation of planar linkages, a new algorithm has been developed to identify the different dyads of a mechanism. A dyad, or class II group, is composed of two binary links connected by either a revolute (1) or a slider (0) pair, with provision for attachment of other links by lower pair connectors located at the end of each link. There are five types of dyad: D111, D101, D011, D001 and D010. The dyad analysis of a mechanism is predicated on the ability to construct the system from one or more of the five binary structure groups or class II groups. If the mechanism is complicated and several dyads are involved, the task of identifying these dyads, by inspection, can be difficult and time consuming for the user. This algorithm allows complete automation of this task. It is based on Dijkstra's algorithm for finding the shortest path in a graph. When compared with algorithmic methods, such as the Newton-Raphson method, the dyad method proved to be a very efficient one and requires as little as one-tenth of the time needed by the method using the Newton-Raphson algorithm. The second part of this work presents an extension of the dyad method to non-rigid or elastic mechanisms. Here also, this method is predicated on the ability to subdivide the elastic mechanism into elastic dyads. The solution for each type of elastic dyad is derived and can be applied to each dyad in the mechanism. Therefore, a solution of the complete elastic mechanism is possible when the mechanism is made of dyads only. This method makes a powerful and simple tool for analysing complex elastic mechanisms. Moreover, the complexity of the model does not increase as the mechanism becomes more complex. The D111 dyad is taken as an example to demonstrate this method. A finite element (FE) analysis was made for this type of dyad, and an experimental set-up was built to validate the analysis. The dyad-FE results were in good agreement with the experimental ones.

Experimental and numerical analysis of the roller-bench endurance test on a motorscooter

2009 ◽  
Vol 223 (5) ◽  
pp. 639-650
Author(s):  
F Frendo ◽  
W Rosellini
Keyword(s):  
Structural Components ◽  
Endurance Test ◽  
Ring Model ◽  
Rigid Frame ◽  
Vertical Accelerations ◽  
Set Up ◽  
Displacement Transducers ◽  
Two Wheeler ◽  
Multi Body ◽  
Good Agreement

This paper describes an activity aimed at analysing the loads occurring on a two-wheeler during one of the most widespread tests among two-wheeler companies. In this test, the vehicle with additional ballasts, is positioned on two rollers, having synchronized rotational speed, and is subjected to loads coming from obstacles positioned on the rollers' surface. In order to achieve an in-depth understanding of the loads produced by the test, a vehicle was provided with displacement transducers, accelerometers, and strain gauges. At the same time, two multi-body models of the test were set up, in which the motorscooter had a rigid frame or a flexible frame respectively. The dynamics of the tyre was reproduced by the rigid ring model, where the tyre interacts with the wheel rim by means of linear and rotational springs and dampers. The loads from the obstacles are evaluated on the basis of a series of experimental curves (envelope properties of the tyre) directly obtained with the tyres and obstacle employed for the tests. The comparison between experimental and numerical results regarding suspension strokes, wheel vertical accelerations, and vertical and longitudinal loads showed fairly good agreement; it is also shown how the model having the rigid frame overestimates the peaks in the vertical load. The availability of an accurate model for this kind of test in the early phase of the development process of new vehicles, allows the design of structural components to be optimized.

scholarly journals Light scattering at small angles by atmospheric irregular particles: modelling and laboratory measurements

2013 ◽  
Vol 6 (4) ◽  
pp. 7565-7591
Author(s):  
T. Lurton ◽  
J.-B. Renard ◽  
D. Vignelles ◽  
M. Jeannot ◽  
R. Akiki ◽  
...  
Keyword(s):  
Light Scattering ◽  
Small Angle ◽  
Dynamic Range ◽  
Roughness Parameter ◽  
Particle Sizes ◽  
Angular Aperture ◽  
Scattering Angle ◽  
Set Up ◽  
Theoretical Results ◽  
Good Agreement

Abstract. We investigated the behaviour of light scattering by particulates of various sizes (0.1 μm to 100 μm) at a small scattering angle. It was previously shown that for a small angle, the scattered intensities are weakly dependent upon the particulates' nature (Renard et al., 2010). Particles found in the atmosphere exhibit roughness that leads to large discrepancies with the classical Mie solution in terms of scattered intensities in the low angular set-up. This article focuses on building an effective theoretical tool to predict the behaviour of light scattering by real particulates at a small scattering angle. We expose both the classical Mie theory and an adaptation to the case of rough particulates with a fairly simple roughness parametrisation. An experimental device was built, corresponding to the angular set-up of interest (low scattering angle and therefore low angular aperture), and measurements are presented that confirm the theoretical results with a good agreement. It is found that the differences between the classical Mie solution and actual measurements, especially for large particulates, can be attributed to the roughness of particulates. It is also found that, in this low angular set-up, saturation of the scattered intensities occurs for relatively small values of the roughness parameter. This confirms the low variability in the scattered intensities for particulates of different kinds. A direct interest of this study is a broadening of the dynamic range of optical counters: using a small angle of aperture for measurements allows greater dynamics in terms of particle size, and thus enables a single device to observe a broad range of particle sizes whilst utilising the same electronics.

Derivation of Position-Probability Density for the Transient Nano-Tunnel Problem in SET

2010 ◽  
Author(s):  
Sheam-Chyun Lin ◽  
Hsien-Chang Shih ◽  
Fu-Sheng Chuang ◽  
Ming-Lun Tsai ◽  
Harki Apri Yanto ◽  
...  
Keyword(s):  
Probability Density ◽  
Error Function ◽  
Closed Form Solution ◽  
Form Solution ◽  
Single Electron ◽  
Mathematical Operation ◽  
Similarity Parameter ◽  
Set Up ◽  
Position Probability ◽  
Good Agreement

This theoretical investigation intends to study the nano-tunnel problem of the single electron transistor (SET), which is one of the most important components in the nano-electronics industry. With a combined effort of quantum mechanics and similarity parameter, the partial differential equation of transient position-probability density is attained and can be applied to predict the electron’s position inside the nano tunnel. Also, an appropriate set of the initial and the boundary conditions is set up in accordance to the actual electron behavior for solving this PDE of probability density function. Thereafter, a simple, closed-form solution for the probability density is obtained and expressed in terms of the error function for a new similarity variable η. Note that this analytic similarity solution is easy to perform the calculation and suitable for any further mathematical operation, such as the optimization applications. In addition, it is shown that these predications are reasonable and in good agreement to the physical meanings, which are evaluated from both microscopic and macroscopic viewpoints. In conclusions, this is an innovative approach by using the Schro¨dinger equation directly to solve the nano-tunnel problem. Moreover, with the aids of this analytic position-probability-density solution, it is illustrated that the free single electron in the SET’s tunnel can only appear at some specified regions, which are defined by a dimensionless parameter η within a range of 0 ≤ η ≤ 2. This result can be served as a valuable design reference for setting the practical manufacture requirement.

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