Bond between deformed reinforcement and normal and high-strength concrete with and without fibers

This paper describes an experimental study that consisted of pullout tests of deformed reinforcing bars in NSC and HSC specimens, with and without hooked-end steel fibers. Two types of test setups were applied, direct and flexural tests, and three bar diameters were tested (8, 12 and 20 mm). The experimental setups were based on standard RILEM pullout (direct) and beam tests, with several modifications. The experimental program included study of the effects of concrete strength and inclusion of steel fibers on the bond strength, as well as the influence of bar geometry and concrete cover. Discussion of the results shows coupling of these effects and proposes an empirical expression that represents this coupling. The results from the current study are also compared with the design bond strengths specified in American and European standards as well as a known model.     

Reflection of plane seismic waves at the surface of double-porosity dual-permeability materials

The present work deals with the reflection of plane seismic waves at the stress-free plane surface of double-porosity dual-permeability material. The incidence of two main waves (i.e., P₁ and SV) is considered. As a result of the incident waves, four reflected (three longitudinal and one shear) waves are found in the medium. The expressions of reflection coefficients for a given incident wave are obtained as a non-singular system of linear equations. The energy shares of reflected waves are obtained in the form of an energy matrix. A numerical example is considered to calculate the partition of incident energy for fully closed as well as perfectly open pores. Effect of incident direction on the partition of the incident energy is analyzed with the change in wave frequency, wave-induced fluid-flow, pore-fluid viscosity and double-porosity structure. It has been confirmed from the numerical interpretation that during the reflection process, conservation of incident energy is obtained at each angle of incidence.     

Unique Requirements of Building Information Modeling for Cast-in-Place Reinforced Concrete

The building information modeling (BIM) tools that have matured for structural steel and precast concrete construction are not suitable for production modeling of cast-in-place (CIP) reinforced concrete structures. The main reason is that CIP structures are monolithic in nature, as opposed to the discrete objects that are typical of steel and precast. A consortium of 12 major contractors and design firms collaborated over a one-year period to formulate the functional requirements for development of a BIM tool for cast-in-place reinforced concrete. The functional requirements were derived from a process model used to scope and understand the processes surrounding reinforced concrete design and production. The functional requirements were finally expressed as a set of object schemas, defining relations, methods, and attributes needed. These are essential for software companies to incorporate in their BIM tools to provide for the unique needs of modeling CIP structures.     

The Anticancer Activity of Organotelluranes: Potential Role in Integrin Inactivation

Organic Te^IV compounds (organotelluranes) differing in their labile ligands exhibited anti‐integrin activities in vitro and anti‐metastatic properties in vivo. They underwent ligand substitution with l ‐cysteine, as a thiol model compound. Unlike inorganic Te^IV compounds, the organotelluranes did not form a stable complex with cysteine, but rather immediately oxidized it. The organotelluranes inhibited integrin functions, such as adhesion, migration, and metalloproteinase secretion mediation in B16F10 murine melanoma cells. In comparison, a reduced derivative with no labile ligand inhibited adhesion of B16F10 cells to a significantly lower extent, thus pointing to the importance of the labile ligands of the Te^IV atom. One of the organotelluranes inhibited circulating cancer cells in vivo, possibly by integrin inhibition. Our results extend the current knowledge on the reactivity and mechanism of organotelluranes with different labile ligands and highlight their clinical potential.     

Intergroup competition for public goods: Effects of unequal resources and relative group size.

Studied single-stage intergroup competition for public goods in small groups with total resources of equal size and binary contributions. In Experiment 1, the two competing groups were of equal size, but the individual resources (endowments) within each group differed from one member to another. The main finding was a negative relation between the endowment size and the likelihood of contribution. In Experiment 2, the ratio of public good to endowment was the same for all members of both groups, but sizes of the groups were unequal. We found no effect of group size per se on level of contribution. Theoretical and methodological implication of the findings are briefly discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fuzzy control of environmentally conscious refrigeration systems

This paper introduces the reader to the concepts of fuzzy sets and fuzzy logic and to their capabilities in the area of control systems. To understand the capabilities of fuzzy logic in real-time controller design, a controller for an environmentally conscious refrigeration system was designed and implemented. Initial results show that a fuzzy logic controller is easy to implement, does not need an exact system model, does not need precise and expensive hardware, and deals with human concepts in a fairly natural and obvious way. This would be, hopefully, a potential avenue for future production of intelligent manufactured products.     

Decomposing and Solving Timetabling Constraint Networks

The binary version of the school timetabling (STT) problem is a real‐world example of a constraint network that includes only constraints of inequality. A new and useful representation for this real‐world problem, the STT_Grid, leads to a generic decomposition technique. The paper presents proofs of necessary and sufficient conditions for the existence of a solution to decomposed STT_Grids. The decomposition procedure is of low enough complexity to be practical for large problems, such as a real‐world high school.
To test the decomposition approach, a typical high school was analyzed and used as a model for generating STT_Grids of various sizes. Experiments were conducted to test the difficulty of large STT networks and their solution by decomposition. The experimental results show that the decomposition procedure enables the solution of large STT_Grids (620 variables for a real school) in reasonable time. The constraint network of a typical STT_Grid is sparse and belongs to the class of easy problems. Still, due to the sizes of STTs, good constraint satisfaction problem search techniques (i.e., BackJumping and ForwardChecking) do not terminate in reasonable times for STT_Grids that are larger than 300 variables.