Drawing bridges by computer

The graphical technique presented in this paper allows the user to draw almost any type of bridge. Bridges are created as graphical variables and can be easily manipulated. Different kinds of bridges are classified and specified according to the characteristics of the road, the piers, the superstructure and the parapets. Several examples are presented. The terminology used stems from the use of Pascal.     

Improved synthesis of oxymethylene-linked poly(oxyethylene)

Polyethylene glycol 400 was reacted with CH₂Cl₂ in the presence of KOH to form oxymethylene-linked chains. The method gave a high yield of colourless high-molecular-weight elastomer. The ionic conductivity of a mixture of the polymer with LiCF₃SO₃ ([O]/[Li] = 25) was about 5 × 10^?5S cm^?1 at 25°C.     

Contribution a l'etude des proprietes magnetiques du dichlorure de vanadium VCl2

The magnetic properties of VCl₂ have been interpreted on the basis of a G.S. Rushbrooke et P.J. Wood model for Heisenberg bidimensional interactions. The calculation of the exchange integral leads to a value of $\text{J}\text{k}{}_{\mathrm{b}}$ close to ? 22,5 K. The strong antiferromagnetic intraplanar V – V interactions seem to result from direct t_2g - t_2g coupling.     

Techniques de mesure des coefficients d'heterodiffusion dans le plutonium. Application a la diffusion du cobalt dans le plutonium ϵ(cc)

The diffusion of ⁶⁰Co in bec ? plutonium has been studied by the sectioning method, and the following results have been obtained: D = 1.4 × 10^?3 exp (?9900/RT) cm²/sec over the temperature range 484–621°C. Cobalt diffuses rapidly in ? Pu. Since the diffusion coefficient does not change across the phase transition ? Pu (fcc) → ? (bcc), the diffusion mechanism must be dissociative in the two phases.     

Die elektrische Leitfähigkeit metallkeramischer Werkstoffe der Systeme ZrO2-Mo und Al2O3-Fe zwischen 20 und 1700°C

Berechnung der elektrischen Leitfähigkeit metallkeramischer Werkstoffe. Erklärung der sprunghaften Leitfähigkeitsänderung mit einem Polyedermodell. Messung der elektrischen Leitfähigkeit an gesinterten Metallkeramiken aus elektronenleitendem Zirkonoxid und Molybdän, stabilisiertem, ionenleitendem Zirkonoxid und Molybdän sowie aus Aluminiumoxid und Eisen. Einfluß der Ausgangskorngröße der oxidischen Komponente auf die elektrische Leitfähigkeit.     

To be nano or not to be nano?

Nanomaterials, nanostructures, nanostructured materials, nanoimprint, nanobiotechnology, nanophysics, nanochemistry, radical nanotechnology, nanosciences, nanooptics, nanoelectronics, nanorobotics, nanosoldiers, nanomedecine, nanoeconomy, nanobusiness, nanolawyer, nanoethics to name a few of the nanos. We need a clear definition of all these burgeoning fields for the sake of the grant attribution, for the sake of research program definition, and to avoid everyone being lost in so many nanos.     

ADF95: Tool for automatic differentiation of a FORTRAN code designed for large numbers of independent variables

ADF95 is a tool to automatically calculate numerical first derivatives for any mathematical expression as a function of user defined independent variables. Accuracy of derivatives is achieved within machine precision. ADF95 may be applied to any FORTRAN 77/90/95 conforming code and requires minimal changes by the user. It provides a new derived data type that holds the value and derivatives and applies forward differencing by overloading all FORTRAN operators and intrinsic functions. An efficient indexing technique leads to a reduced memory usage and a substantially increased performance gain over other available tools with operator overloading. This gain is especially pronounced for sparse systems with large number of independent variables. A wide class of numerical simulations, e.g., those employing implicit solvers, can profit from ADF95.

Program summary

Title of program:ADF95Catalogue identifier: ADVIProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVIProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandComputer for which the program is designed: all platforms with a FORTRAN 95 compilerProgramming language used:FORTRAN 95No. of lines in distributed program, including test data, etc.: 3103No. of bytes in distributed program, including test data, etc.: 9862Distribution format: tar.gzNature of problem: In many areas in the computational sciences first order partial derivatives for large and complex sets of equations are needed with machine precision accuracy. For example, any implicit or semi-implicit solver requires the computation of the Jacobian matrix, which contains the first derivatives with respect to the independent variables. ADF95 is a software module to facilitate the automatic computation of the first partial derivatives of any arbitrarily complex mathematical FORTRAN expression. The program exploits the sparsity inherited by many set of equations thereby enabling faster computations compared to alternate differentiation toolsSolution method: A class is constructed which applies the chain rule of differentiation to any FORTRAN expression, to compute the first derivatives by forward differencing. An efficient indexing technique leads to a reduced memory usage and a substantially increased performance gain when sparsity can be exploited. From a users point of view, only minimal changes to his/her original code are needed in order to compute the first derivatives of any expression in the codeRestrictions: Processor and memory hardware may restrict both the possible number of independent variables and the computation timeUnusual features:ADF95 can operate on user code that makes use of the array features introduced in FORTRAN 90. A convenient extraction subroutine for the Jacobian matrix is also providedRunning time: In many realistic cases, the evaluation of the first order derivatives of a mathematical expression is only six times slower compared to the evaluation of analytically derived and hard-coded expressions. The actual factor depends on the underlying set of equations for which derivatives are to be calculated, the number of independent variables, the sparsity and on the FORTRAN 95 compiler