Good ergonomics and team diversity reduce absenteeism and errors in car manufacturing

Prior research suggests that ergonomics work design and mixed teams (in age and gender) may compensate declines in certain abilities of ageing employees. This study investigates simultaneous effects of both team level factors on absenteeism and performance (error rates) over one year in a sample of 56 car assembly teams (N = 623). Results show that age was related to prolonged absenteeism and more mistakes in work planning, but not to overall performance. In comparison, high-physical workload was strongly associated with longer absenteeism and increased error rates. Furthermore, controlling for physical workload, age diversity was related to shorter absenteeism, and the presence of females in the team was associated with shorter absenteeism and better performance. In summary, this study suggests that both ergonomics work design and mixed team composition may compensate age-related productivity risks in manufacturing by maintaining the work ability of older employees and improving job quality.     

Maple procedures for the coupling of angular momenta. An up-date of the Racah module

An up-date of the Racah module is presented, adopted to Maple 11 and 12, which supports both, algebraic manipulations of expressions from Racah's algebra as well as numerical computations of many functions and symbols from the theory of angular momentum. The functions that are known to the program include the Wigner rotation matrices and n-j symbols, Clebsch-Gordan and Gaunt coefficients, spherical harmonics of various kinds as well as several others.

Program summary

Program title:RacahCatalogue identifier: ADFV_v10_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADFV_v10_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 30 436No. of bytes in distributed program, including test data, etc.: 544 866Distribution format: tar.gzProgramming language: Maple 11 and 12Computer: All computers with a license for the computer algebra package Maple [1]Operating system: Suse Linux 10.2+ and Ubuntu 8.10Classification: 4.1, 5Catalogue identifier of previous version: ADFV_v9_0Journal reference of previous version: Comput. Phys. Comm. 174 (2006) 616Does the new version supersede the previous version?: YesNature of problem: The theories of angular momentum and spherical tensor operators, sometimes known also as Racah's algebra, provide a powerful calculus for studying spin networks and (quantum) many-particle systems. For an efficient use of these theories, however, one requires not only a reliable handling of a large number of algebraic transformations and rules but, more often than not, also a fast access to their standard quantities, such as the Wigner n-j symbols, Clebsch-Gordan coefficients, spherical harmonics of various kinds, the rotation matrices, and many others.Solution method: A set of Maple procedures has been developed and maintained during the last decade which supports both, algebraic manipulations as well as fast computations of the standard expressions and symbols from the theory of angular momentum [2,3]. These procedures are based on a sizeable set of group-theoretical (and often rather sophisticated) relations which has been discussed and proven in the literature; see the monograph by Varshalovich et al. [4] for a comprehensive compilation. In particular the algebraic manipulation of complex (Racah) expressions may result in considerable simplifications, thus reducing the ‘numerical costs’, and often help obtain further insight into the behaviour of physical systems.Reasons for new version: A revision of the Racah module became necessary for mainly three reasons: (i) Since the last extension of the Racah procedures [5], which was developed within the framework of Maple 8, several updates of Maple were distributed by the vendors (currently Maple 13) and required a number of adaptations to the source code; (ii) the increasing size and program structure of the Racah module made it advisible to separate the (procedures for the treatment of the) atomic shell model from the manipulation and computation of Racah expressions. Therefore, the computation of angular coefficients for different coupling schemes, (grand) coefficients of fractional parentage as well as the matrix elements (of various irreducible tensors from the shell model) is to be maintained from now on independently within the Jucys module; (iii) a number of bugs and inconsistencies have been reported to us and corrected in the present version.Summary of revisions: In more detail, the following changes have been made:

1.

Since recent versions of Maple now support the automatic type checking of all incoming arguments and the definition of user-defined types; we have adapted most of the code to take advantage of these features, and especially those commands that are accessible by the user.

2.

In the computation of the Wigner n-j symbols and Clebsch-Gordan coefficients, we now return a ‘0’ in all cases in which the triangular rules are not fulfilled, for example, if δ(a,b,c)=0 for or . This change in the program saves the user making these tests on the quantum numbers explicitly everytime (in the summation over more complex expressions) that such a symbol or coefficient is invoked. The program still terminates with an error message if the (half-integer and integer) angular momentum quantum numbers appear in an inproper combination.

3.

While a recursive generation of the Wigner 3-j and 6-j symbols [6] may reduce the costs of some computations (and has thus been utilized in the past), it also makes the program rather sophisticated, especially if an algebraic evaluation or computations with a high number of Digits need to be supported by the same generic commands. The following procedures are therefore no longer supported by the Racah module:Racah_compute_w3j_jrange(), Racah_compute_w3j_mrange(),Racah_compute_w3j_recursive(), Racah_compute_w6j_range(), andRacah_compute_w6j_recursive().On most PCs, a sequential computation of all requested symbols is carried out within the same time basically.

4.

Because the module Jucys has grown to a size of about 35,000 lines of code and data, it appears helpful and necessary to maintain it independently. The procedures from the Jucys modules were designed to facilitate the computation of matrix elements of the unit tensors, the coefficients of fractional parentage (of various types) as well as transformation matrices between different coupling schemes [7] and are, thus, independent of the Racah module (although they typically require that the Racah code is available). The Jucys module is no longer distributed together with the present code.

5.

Apart from the Wigner n-j symbols (see above), some minor bugs have been reported and corrected in Racah_expand() and Racah_set().

6.

To facilitate the test of the installation and as a first tutorial on the module, we now provide the Maple worksheet Racah-tests-2009-maple12.mw in the Racah2009 root directory. This worksheet contains the examples and test cases from the previous versions. For the test of the installation, it is recommended that a ‘copy’ of this worksheet is saved and compared to the results from the re-run. It can be used also as a helpful source to define new examples in interactive work with the Racah module.

The Racah module is distributed in a tar file ADFV_v10_0.tar.gz from which the RACAH2009 root directory is (re-)generated by the command tar -zxvf ADFV_v10_0.tar.gz. This directory contains the source code libraries (tested for Maple 11 and 12), a Read.me for the installation of the program, the worksheet Racah-tests-2009-maple12.mw as well as the document Racah-commands-2009.pdf. This .pdf document serves as a Short Reference Manual and provides the definition of all the data structures of the Racah program together with an alphabetic list of all user relevant (and exported) commands. Although emphasis was placed on preserving the compatibility of the program with earlier releases of Maple, this cannot always be guaranteed due to changes in the Maple syntax. The Racah2009 root also contains an example of a .mapleinit file that can be modified and incorporated into the user's home directory to make the Racah module accessible like any other module of Maple. As mentioned above, the worksheet Racah-tests-2009-maple12.mw, help test the installation and may serve as a first tutorial.Restrictions: The (Racah) program is based on the concept of Racah expressions [cf. Fig. 1 in Ref. [4]] which, in principle, may contain any number of Wigner n-j symbols (n?9), Clebsch-Gordan coefficients, spherical harmonics and/or rotation matrices. In practise, of course, the required time and the success of an evaluation procedure depends on the complexity of the expressions and on the storage available, sometimes also on Maple's internal garbage treatment. In some cases, it is advisable to attempt first a simplification of the magnetic quantum numbers for a given expression before the summation over further 6-j and 9-j symbols should be taken into account. For all other quantities (that are compiled in Ref. [8], Tables 1 and 2, and explained in more detail in the Short Reference Manual, Racah-commands-2009.pdf), we currently just facilitate fast numerical computations by exploiting, as far as possible, Maple's hardware floating-point model. The program also supports simplifications on the Wigner rotation matrices. In integrals over the rotation matrices, products of up to three Wigner D-functions or reduced matrices (with the same angular arguments) are recognized; for the integration over a solid angle, however, the domain of integration must be specified explicitly for the Euler angles α and γ in order to force Maple to generate a constant of integration. In the course of the evaluation of Racah expressions, it is, in practice, often difficult to check internally whether all substructures of an expression are defined properly. Therefore, the user must ensure that all angular momenta (if given explicitly) must finally evaluate to integer and half-integer values and that they satisfy proper coupling conditions.Unusual features: The Racah program is designed for interactive use and for providing a quick and algebraic evaluation of (complex) expressions from Racah's algebra. In the evaluation, it exploits a large set of sum rules which are known from Racah's algebra and which may include (multiple) summations over dummy indices; see Varshalovich et al. [5] for a more detailed account of the theory. One strength of the program is that it recognizes automatically the symmetries of the symbols and functions, and that it applies also (some of) the graphical rules due to Yutsis and coworkers [9]. As before, the result of the evaluation process will be provided as Racah expressions, if a further simplification could be achieved, and may hence be used for further derivations and calculations within the given framework. In dealing with recoupling coefficients, these coefficients can be entered simply as a string of angular momenta (variables), separated by commas, and very similar to how they appear in mathematical texts. This is a crucial advantage of the program, compared with previous developments, for which the angular momenta and coupling coefficients had often to be given in a very detailed format. A Short Reference Manual to all procedures of the Racah program is provided by this distribution; it also contains the worksheet Racah-tests-2009-maple12.mw that contains the examples from all previous versions and may help test the installation. This worksheet can serve as a first tutorial to the Racah procedures. In the past, the Racah program has been utilized extensively in a number of applications including angular and polarization studies of heavy ions [10], angular distributions and correlation functions following photon-induced excitation processes [11], entanglement studies [12], in application of point-group symmetries and several others.Running time: The worksheet supplied with the distribution takes about 1 minute to run.References:

[1] Maple is a registered trademark of Waterloo Maple Inc.

[2] S. Fritzsche, Comp. Phys. Commun. 103 (1997) 51.

[3] S. Fritzsche, S. Varga, D. Geschke, B. Fricke, Comp. Phys. Commun. 111 (1998) 167;

T. Ingho, S. Fritzsche, B. Fricke, Comp. Phys. Commun. 139 (2001) 297;

S. Fritzsche, T. Ingho, T. Bastug, M. Tomaselli, Comp. Phys. Commun. 139 (2001) 314.

[4] D.A. Varshalovich, A.N. Moskalev, V.K. Khersonskii, Quantum Theory of Angular Momentum, World Scientific, Singapore a.o., 1988.

[5] J. Pagaran, S. Fritzsche, G. Gaigalas, Comp. Phys. Commun. 174 (2006) 616.

[6] K. Schulten, R.G. Gordon, Comp. Phys. Commun. 11 (1976) 269.

[7] G. Gaigalas, S. Fritzsche, B. Fricke, Comp. Phys. Commun. 135 (2001) 219;

G. Gaigalas, S. Fritzsche, Comp. Phys. Commun. 149 (2002) 39;

G. Gaigalas, O. Scharf, S. Fritzsche, Comp. Phys. Commun. 166 (2005) 141.

[8] S. Fritzsche, T. Ingho, M. Tomaselli, Comp. Phys. Commun. 153 (2003) 424.

[9] A.P. Yutsis, I.B. Levinson, V.V. Vanagas, The Theory of Angular Momentum, Israel Program for Scientific Translation, Jerusalem, 1962.

[10] S. Fritzsche, P. Indelicato, T. Stöhlker, J. Phys. B 38 (2005) S707.

[11] M. Kitajima, M. Okamoto, M. Hoshino, et al., J. Phys. B 35 (2002) 3327;

N.M. Kabachnik, S. Fritzsche, A.N. Grum-Grzhimailo, et al., Phys. Reports 451 (2007) 155;

S. Fritzsche, A.N. Grum-Grzhimailo, E.V. Gryzlova, N.M. Kabachnik, J. Phys. B 41 (2008) 165601;

T. Radtke, et al., Phys. Rev. A 77 (2008) 022507.

[12] T. Radtke, S. Fritzsche, Comp. Phys. Commun. 175 (2006) 145.

     

The Ratip program for relativistic calculations of atomic transition,ionization and recombination properties

During the past decade, the Ratip program has been developed to calculate the electronic structure and properties of atoms and ions. This code, which is now organized as a suite of programs, provides a powerful platform today to generate and evaluate atomic data for open-shell atoms, including level energies and energy shifts, transition probabilities, Auger parameters as well as a variety of excitation, ionization and recombination amplitudes and cross sections. Although the Ratip program focus on properties with just one electron within the continuum, recent emphasis was placed also on second-order processes as well as on the combination of different types of transition amplitudes in order to explore more complex spectra. Here, I present and discuss the (design of the) Ratip program and make available a major part of the code for public use. Selected examples show a few of its possible applications, while reference is made to a much wider range of computations as supported by the program. The Ratip program has been developed as a scalar Fortran 90/95 code and provides a simple make feature which help port the code to different platforms and architectures.Program summaryProgram title: RatipCatalogue identifier: AEMA_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMA_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 256 562No. of bytes in distributed program, including test data, etc.: 4 975 979Distribution format: tar.gzProgramming language: ANSI standard Fortran 90/95 and subsequent developmentsComputer: PCs and workstationsOperating system: Suse, Debian and Ubuntu LinuxRAM: Memory requirements strongly depend on the size of the bound-state wave functions, the property considered as well as the special features selected during the computations.Word size: All real variables are parametrized by a selected kind parameter and, thus, can easily be adapted to any required precision as supported by the compiler. Presently, the kind parameter is set to double precision (two 32-bit words) in the module rabs_constant.Classification: 2.1, 2.9Subprograms used:     

5.

Where does model-driven engineering help? Experiences from three industrial cases     

Parastoo Mohagheghi  Wasif Gilani  Alin Stefanescu  Miguel A. Fernandez  Bjørn Nordmoen  Mathias Fritzsche 《Software and Systems Modeling》2013,12(3):619-639

There have been few experience reports from industry on how Model-Driven Engineering (MDE) is applied and what the benefits are. This paper summarizes the experiences of three large industrial participants in a European research project with the objective of developing techniques and tools for applying MDE on the development of large and complex software systems. The participants had varying degrees of previous experience with MDE. They found MDE to be particularly useful for providing abstractions of complex systems at multiple levels or from different viewpoints, for the development of domain-specific models that facilitate communication with non-technical experts, for the purposes of simulation and testing, and for the consumption of models for analysis, such as performance-related decision support and system design improvements. From the industrial perspective, a methodology is considered to be useful and cost-efficient if it is possible to reuse solutions in multiple projects or products. However, developing reusable solutions required extra effort and sometimes had a negative impact on the performance of tools. While the companies identified several benefits of MDE, merging different tools with one another in a seamless development environment required several transformations, which increased the required implementation effort and complexity. Additionally, user-friendliness of tools and the provision of features for managing models of complex systems were identified as crucial for a wider industrial adoption of MDE.     

6.

The Role of oxygen diffusion in photoinduced changes of the electronic and optical properties in amorphous indium oxide     

B. Claflin  H. Fritzsche 《Journal of Electronic Materials》1996,25(11):1772-1777

A stable increase by as much as 10⁸ in the conductivity of amorphous indium oxide to σ≥ 10³Ω^-1 cm₋₁ can be achieved by ultraviolet photoreduction. This treatment also increases the absorption coefficient, α(hυ), by up to a factor of 10₃ for hυ <1.5 eV due to free carrier absorption and causes a 0.1 eV shift of the absorption edge to the blue. These changes are controlled by the Fermi level, EF, which is presumably determined by doping due to oxygen vacancies. A diffusion constant D >3 x 10⁻¹² cm²/s for oxygen at 300K is determined from a constant flow experiment. Oxygen diffusion is verified by secondary ion mass spectrometry with ¹⁸O. The functions α(hυ) and σ(T) are simulated as E_F is varied using a simple density of states model appropriate for amorphous semiconductors. These simulations qualitatively agree with the experimental data if transitions from the conduction band tail to the conduction band are assumed to be forbidden.     

7.

Corrigendum to “In-situ neutron diffraction investigation of Mg2FeH6 dehydrogenation” [Int J Hydrogen Energy 42 (2017) 3087–3096]     

Julien Lang  Helmut Fritzsche  Alexandre Augusto Cesario Asselli  Jacques Huot 《International Journal of Hydrogen Energy》2017,42(18):13307

     

8.

Use of group theory for the analysis of vibrational spectra     

K. Rykhlinskaya  S. Fritzsche 《Computer Physics Communications》2004,162(2):124-142

     

9.

Speckle interferometry for spectral analysis of laser sources and multimode optical waveguides     

Freude  W. Fritzsche  C. Grau  G. Lu Shan-da 《Lightwave Technology, Journal of》1986,4(1):64-72

Speckle phenomena in optical waveguides known as modal noise are useful for measuring the spectral width of laser sources down to 1 MHz or the bandwidth of multimode fibers up to 1 THz. This measurement is based on a theory relating the frequency correlation function of a speckle pattern to the light source spectrum and to the power transfer function of general waveguides. We demonstrate the feasibility of the method by investigating laser lines with a width of 300 MHz and 5 GHz, and by studying the transmission characteristics of short fiber pieces with bandwidths up to 37 GHz.     

10.

Erratum: "Speckle interferometry for spectral analysis of laser sources and multimode optical waveguides"     

Freude  W. Fritzsche  C. Grau  G. Lu Shan-da 《Lightwave Technology, Journal of》1986,4(6):694-694

     

1 [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] 下一页 » 末  页»

Where does model-driven engineering help? Experiences from three industrial cases

There have been few experience reports from industry on how Model-Driven Engineering (MDE) is applied and what the benefits are. This paper summarizes the experiences of three large industrial participants in a European research project with the objective of developing techniques and tools for applying MDE on the development of large and complex software systems. The participants had varying degrees of previous experience with MDE. They found MDE to be particularly useful for providing abstractions of complex systems at multiple levels or from different viewpoints, for the development of domain-specific models that facilitate communication with non-technical experts, for the purposes of simulation and testing, and for the consumption of models for analysis, such as performance-related decision support and system design improvements. From the industrial perspective, a methodology is considered to be useful and cost-efficient if it is possible to reuse solutions in multiple projects or products. However, developing reusable solutions required extra effort and sometimes had a negative impact on the performance of tools. While the companies identified several benefits of MDE, merging different tools with one another in a seamless development environment required several transformations, which increased the required implementation effort and complexity. Additionally, user-friendliness of tools and the provision of features for managing models of complex systems were identified as crucial for a wider industrial adoption of MDE.     

The Role of oxygen diffusion in photoinduced changes of the electronic and optical properties in amorphous indium oxide

A stable increase by as much as 10⁸ in the conductivity of amorphous indium oxide to σ≥ 10³Ω^-1 cm₋₁ can be achieved by ultraviolet photoreduction. This treatment also increases the absorption coefficient, α(hυ), by up to a factor of 10₃ for hυ <1.5 eV due to free carrier absorption and causes a 0.1 eV shift of the absorption edge to the blue. These changes are controlled by the Fermi level, EF, which is presumably determined by doping due to oxygen vacancies. A diffusion constant D >3 x 10⁻¹² cm²/s for oxygen at 300K is determined from a constant flow experiment. Oxygen diffusion is verified by secondary ion mass spectrometry with ¹⁸O. The functions α(hυ) and σ(T) are simulated as E_F is varied using a simple density of states model appropriate for amorphous semiconductors. These simulations qualitatively agree with the experimental data if transitions from the conduction band tail to the conduction band are assumed to be forbidden.     

Speckle interferometry for spectral analysis of laser sources and multimode optical waveguides

Speckle phenomena in optical waveguides known as modal noise are useful for measuring the spectral width of laser sources down to 1 MHz or the bandwidth of multimode fibers up to 1 THz. This measurement is based on a theory relating the frequency correlation function of a speckle pattern to the light source spectrum and to the power transfer function of general waveguides. We demonstrate the feasibility of the method by investigating laser lines with a width of 300 MHz and 5 GHz, and by studying the transmission characteristics of short fiber pieces with bandwidths up to 37 GHz.