The effect of borax pentahydrate addition to urea formaldehyde on the mechanical characteristics and free formaldehyde content of plywood

In this study, the effects of borax pentahydrate addition to urea formaldehyde (UF) on the bonding characteristics and free formaldehyde content have been studied. Experiments related to the bending strength, withdrawal shear strength and free formaldehyde content have been conducted on the three-layered beech and poplar plywood which are prepared by the addition of borax pentahydrate into their adhesive mixtures in certain amounts. Addition of borax pentahydrate into the adhesive mixture did not statistically affect the bending strength and withdrawal shear strength of the plywood but did reduce the free formaldehyde content.     

Mechanical Properties and Corrosion Behavior of As-Cast Mg-Zn-Zr-(La) Magnesium Alloys

The effects of La content on the mechanical properties and corrosion behavior of as-cast Mg-Zn-Zr (ZK) magnesium alloys were investigated. The results showed that La addition to ZK60 alloy resulted in a considerable grain refinement and an increase in the volume fraction of second phases by formation of Mg-Zn-La ternary phase. The tensile tests were performed at both room and elevated temperatures. At room temperature, the yield and tensile strengths and elongation-to-fracture significantly increased with 0.2 wt.% La addition, then deteriorated slightly with increasing La additions above 0.2 wt.%. At 200 °C, the yield and tensile strengths continually improved and elongation-to-fracture decreased with increasing La content due to the presence of thermally stable Mg-Zn-La phase. Immersion and electrochemical corrosion tests revealed that the formation of Mg-Zn-La phases led to a higher amount of cathodic sites and preferential corrosion propagation, and thus a decrease in the corrosion resistance of ZK60 alloys.     

Erbium(III)‐doped polyurethaneureas: Novel broadband ultraviolet‐to‐visible converters

Novel, polymeric UV‐to‐visible converters were prepared by doping elastomeric poly(ether‐urethaneurea) copolymers with 5–25% by weight of ErCl₃ 6H₂O, corresponding to Er³⁺ concentrations of 2.19 to 10.86% by weight. When excited in the UV at 355 nm, the doped films generated a very broad, continuous visible luminescence between 400 and 750 nm. Preparation and spectroscopic characterization of the samples are discussed in detail. The color coordinates, color temperature, color rendering index of the samples, and the degree of overlap of their emission bands with the spectral response of the eye were determined. The color rendering index of samples is in the 57–70 range. The sample containing 2.19% by weight of Er³⁺ was found to give the color coordinates closest to the white‐source region and the highest color rendering index. The color temperatures of the samples were in the 5093–5540 K range. Overlap between the emission bands and the spectral response of the eye improved with increasing erbium concentration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A team-oriented design methodology for mixed model assembly systems

Team-oriented approaches are widely being used in modern real life assembly systems, as are other modern systems. In this paper, first the literature of single and mixed model assembly line balancing, which plays an important role for the design of assembly systems, is reviewed. The associated literature matrixes reveal that team-oriented approaches do not have an intensive research area. Second, a team-oriented mathematical programming model for creating assembly teams (physical stations) in mixed model assembly lines is devised. Owing to the fact that this model is NP hard, a scheduling based heuristic algorithm is developed. The mixed model assembly line design methodology, which includes a team-oriented algorithm as a step, is proposed. Both model sequencing and worker transfer systems are included in the methodology. The algorithms for each step of the methodology are also coded by using MATLAB and MS Excel is used as the user interface. Furthermore, the presented methodology was applied in a chosen segment of a real life mixed model tractor assembly system.     

A randomized prospective trial comparing 45 and 90-ml oral sodium phosphate with X-Prep in the preparation of patients for colonoscopy

Incontinentia pigmenti is an uncommon genodermatosis that occurs in female infants. The characteristic dental defects are partial anodontia and the presence of some peg-shaped teeth. This report describes a patient with incontinentia pigmenti who exhibited multiple missing teeth in both arches. The patient had malpositioned teeth and decreased occlusal vertical dimension associated with the missing teeth. Orthodontic treatment was required for prosthetic purposes. The dental anomalies of incontinentia pigmenti and the treatment procedure are presented.     

SoSyM significantly reduces its backlog

Software and Systems Modeling -     

Using heuristic algorithms for capacity leasing and task allocation issues in telecommunication networks under fuzzy quality of service constraints

Nowadays, every firm uses telecommunication networks in different amounts and ways in order to complete their daily operations. In this article, we investigate an optimisation problem that a firm faces when acquiring network capacity from a market in which there exist several network providers offering different pricing and quality of service (QoS) schemes. The QoS level guaranteed by network providers and the minimum quality level of service, which is needed for accomplishing the operations are denoted as fuzzy numbers in order to handle the non-deterministic nature of the telecommunication network environment. Interestingly, the mathematical formulation of the aforementioned problem leads to the special case of a well-known two-dimensional bin packing problem, which is famous for its computational complexity. We propose two different heuristic solution procedures that have the capability of solving the resulting nonlinear mixed integer programming model with fuzzy constraints. In conclusion, the efficiency of each algorithm is tested in several test instances to demonstrate the applicability of the methodology.     

Static and dynamic bifurcations associated with a double-zero eigenvalue

This paper is concerned with the static and dynamic bifurcation phenomena exhibited by a nonlinear autonomous system in the vicinity of a double-zero eigenvalue. It is demonstrated analytically that such a coincident critical point is often located on the intersection of the divergence and flutter boundaries of the system. The analysis is performed via a new 'unification technique' which is based on an intrinsic perturbation procedure. The new approach is capable of yielding information about stability of solutions as well as incipient and secondary bifurcations. Indeed, the stability properties of the system and secondary Hopf bifurcations are discussed conveniently, and explicit results concerning post-critical solutions are presented. An illustrative example is analysed.