Towards a contingent approach of customer involvement in defence projects: An exploratory study

This paper reports the main results of an exploratory, multiple case study investigating customer involvement practices in system development projects in the Israeli defence industry. The study proposes and examines a theoretical contingency model regarding the effect of customer involvement modes on project success, moderated by project characteristics. It focuses specifically on the working mode of customers' representatives along the continuum between external supervision to full participation in project activities.     

Using Modeling Tasks to Facilitate the Development of Percentages

This study analyzes the development of percentages knowledge by seventh graders given a sequence of activities starting with a realistic modeling task, in which students were expected to create a model that would facilitate the reinvention of percentages. In the first two activities, students constructed their own pricing model using fractions and then extended the model while experiencing reinvention and extension of their knowledge of percentages. In the last two activities, they coped with a realistic changing reference situation. A control group used a traditional instructional unit. A pretest and two posttests showed between-group differences.     

Harnessing “Click”‐Type Chemistry for the Preparation of Novel Electronic Materials

Sequence‐independent or “click”‐type chemistry is applied for the preparation of novel π‐conjugated oligomers. A variety of bi‐functional monomers for Wittig–Horner olefination are developed and applied in a sequential protection–deprotection process for the preparation of structurally similar π‐conjugated oligomers. Selected oligomers are incorporated as the organic semiconductors in light‐emitting diodes and a field‐effect transistor, demonstrating the potential of the approach.     

A bacteriophage reagent for Salmonella: molecular studies on Felix 01

Felix 01 (F01) is a bacteriophage originally isolated by Felix and Callow which lyses almost all Salmonella strains and has been widely used as a diagnostic test for this genus. Molecular information about this phage is entirely lacking. In the present study, the DNA of the phage was found to be a double-stranded linear molecule of about 80 kb. 11.5 kb has been sequenced and in this region A + T content is 60%. There are relatively few restriction endonuclease cleavage sites in the native genome and clones show this is due to their absence rather than modification. A restriction map of the genome has been constructed. The ends of the molecule cannot be ligated although they contain 5' phosphates. At least 60% of the genome must encode proteins. In the sequenced portion, many open reading frames exist and these are tightly packed together. These have been examined for homology to published proteins but only 1 to 17 shows similarity to known proteins. F01 is therefore the prototype of a new phage family. On the basis of restriction sites, codon usage and the distribution of nonsense codons in the unused reading frames, a strong case can be made for natural selection that reacts to mRNA structure and function.     

Multiconsistency and Robustness with Global Constraints

We propose a natural generalization of arc-consistency, which we call multiconsistency: a value v in the domain of a variable x is k-multiconsistent with respect to a constraint C if there are at least k solutions to C in which x is assigned the value v. We present algorithms that determine which variable-value pairs are k-multiconsistent with respect to several well known global constraints. In addition, we show that finding super solutions is sometimes strictly harder than finding arbitrary solutions for these constraints and suggest multiconsistency as an alternative way to search for robust solutions.Supported by the Danish Research Agency (grant # 272-05-0081).Basic Research in Computer Science, funded by the Danish National Research Foundation.     

Quantifying delineation errors in thin film resistors II: Evaluation of etching rates from resistance measurements

The evaluation of the etching rate in thin film resistor delineation processes is considered in this paper. The calculation of the absolute etching linewidth error from sample resistance measurements has been considered in a previous paper.The method is extended in this paper to allow a dynamic (time-dependent) characterization of the linewidth overetching.     

On the pH-Dependence of Greducing in the Radiation Chemistry of Aqueous Solutions

Alkaline N₂O-saturated solutions of 2-D-2-propanol and ferri-ferrocyanide mixtures were irradiated. The results indicate that G_red, which is the sum of G_eaq + G_H = 3.3, is pH-independent in the range 11 – 14. The results do not indicate that G_eaq and G_H are pH-dependent.     

Analysis of the impedance spectra of short conductive fiber-reinforced composites

The presence of small amounts of short conductive fibers in a composite of finite matrix conductivity results in the subdivision of the one matrix impedance arc into two separate low and high frequency arcs in the complex impedance plane. These features are attributable to a frequency-switchable interfacial impedance on the fiber surfaces, rendering them insulating at DC and low AC frequencies, but conducting at intermediate frequencies. A combination of physical simulations (single wires in tap water) and pixel-based computer modeling was employed to investigate the roles of fiber pull-out, debonding, and orientation on the impedance response of fiber-reinforced composites. The ratio of the low frequency arc size to the overall DC resistance (-parameter) is sensitive to pull-out and/or debonding, especially when a fiber just barely makes contact with the matrix. The -parameter is also quite sensitive to fiber orientation with respect to the direction of the applied field. Ramifications for the characterization of cement, ceramic, and polymer matrix composites are discussed.     

Confinement of Damaged and Nondamaged Structural Concrete with FRP and TRC Sleeves

The potential for using textiles impregnated with cement as a means for in situ strengthening and retrofit of structural concrete was explored and compared with the conventional epoxy method. Fabrics of different geometries, yarns, and modulus values were evaluated. Simulation of repair and strengthening was carried out by wrapping fabric impregnated with cement and epoxy around damaged and undamaged concrete cylinders. The cylinders with the impregnated sleeves were loaded in compression, and their performance was compared with that of the “virgin” (control) concrete. In addition, the mechanical properties of the cement composite layer were evaluated, as well as the stiffness of the fabrics themselves, and correlated with that of the repaired system. Efficient repair with the cement binder was accomplished with the high modulus fabric (Kevlar) in particular. However, even the lower modulus (polypropylene) could be effective in repairing and inducing some postpeak resistance (although to a smaller extent than with the Kevlar). Improved behavior was also obtained with the nondamaged concrete cylinder when it was strengthened with the cement–fabric jacket, mainly at composite strain values of up to 0.2–0.3%.