Effect of some additions on the microstructure and mechanical,fatigue, and friction properties of sintered lead bronze

Conclusions In an investigation into the effect of Zn, Ni, As, P, Fe, Sn, and Sb on the properties of sintered lead bronze with 30% Pb it was established that all the additions except iron and phosphorus increase in varying degrees the strength, hardness, and resistance to fatigue stresses of the material. All the additions adversely affect its coefficient of friction.Individual elements affect the properties mentioned above by changing both the structure of the bronze and the dihedral angles between its copper and lead constituents. With tin and antimony additions, dihedral angles of more than 60° are recorded; as a result, the resistance to fatigue stresses and strength of the bronze increase, but its coefficient of friction also rises.With structures characterized by dihedral angles smaller than 60°, no significant changes in properties are observed compared with the alloy without an addition; in fact, properties may actually be lowered. On the basis of the results obtained, it may be recommended that, taking into account the required load-carrying capacity and bearing life, tin or antimony should be added to lead bronze in amounts necessary for improving the friction properties of parts.Translated from Poroshkovaya Metallurgiya, No. 7 (103), pp. 98–104, July, 1971.     

Characterization of T-measures

As a natural generalization of a measure space, Butnariu and Klement introduced T-tribes of fuzzy sets with T-measures. They made the first steps towards a characterization of monotonic real-valued T-measures for a Frank triangular norm T. Later on, Mesiar and the authors of this paper found independently two generalizations, one for vector-valued T-measures with respect to Frank t-norms (in particular for nonmonotonic ones) [3], the other for monotonic real-valued T-measures with respect to general strict t-norms [15]. Here we present a common generalization – a characterization of nonmonotonic T-measures with respect to an arbitrary strict t-norm. Moreover, we prove this for vector-valued T-measures. Using this characterization, we generalize Ljapunov Theorem to this context.The authors gratefully acknowledge the support of Ministero dell'Universit'91a e della Ricerca Scientifica e Tecnologica (Italy), grant 201/02/1540 of the Grant Agency of the Czech Republic, and the Czech Ministry of Education under Research Programme MSM 212300013 Decision Making and Control in Manufacturing.     

Selection of Optimal Stopping Time for Nonlinear Diffusion Filtering

We develop a novel time-selection strategy for iterative image restoration techniques: the stopping time is chosen so that the correlation of signal and noise in the filtered image is minimized. The new method is applicable to any images where the noise to be removed is uncorrelated with the signal, under the assumptions that the filter used is suitable for the given type of data, and that neither the additive noise nor the filtering procedure alter the average gray value; no other knowledge (e.g. the noise variance, training data etc.) is needed.We analyse the theoretical properties of the method, then test the performance of our time estimation procedure experimentally, and demonstrate that it yields near-optimal results for a wide range of noise levels and for various filtering methods.     

Reversible Lectin Binding to Glycan-Functionalized Graphene

The monolayer character of two-dimensional materials predestines them for application as active layers of sensors. However, their inherent high sensitivity is always accompanied by a low selectivity. Chemical functionalization of two-dimensional materials has emerged as a promising way to overcome the selectivity issues. Here, we demonstrate efficient graphene functionalization with carbohydrate ligands—chitooligomers, which bind proteins of the lectin family with high selectivity. Successful grafting of a chitooligomer library was thoroughly characterized, and glycan binding to wheat germ agglutinin was studied by a series of methods. The results demonstrate that the protein quaternary structure remains intact after binding to the functionalized graphene, and that the lectin can be liberated from the surface by the addition of a binding competitor. The chemoenzymatic assay with a horseradish peroxidase conjugate also confirmed the intact catalytic properties of the enzyme. The present approach thus paves the way towards graphene-based sensors for carbohydrate–lectin binding.     

Alpha-cyano-beta-hydroxy-beta-methyl-N-[4-(trifluoromethoxy)phenyl] propenamide: an inhibitor of the epidermal growth factor receptor tyrosine kinase with potent cytotoxic activity against breast cancer cells

Epidermal growth factor receptor (EGF-R) tyrosine kinase is known to be overexpressed in several malignancies and is an important target for anticancer drug design. We constructed a homology model to represent the structure of EGF-R and propose that this model can be used to design potent inhibitors of EGF-R. We used our EGF-R model and a docking procedure to rationally design compounds predicted to bind favorably to EGF-R. This approach led to the successful design of a leflunomide metabolite analogue, which was found to have an IC50 value of 1.7 microM in EGF-R inhibition assays and killed >99% of human breast cancer cells in vitro by triggering apoptosis. The reported studies may provide the basis for the development of a new class of potent and clinically useful anti-breast cancer agents.     

Wear performance and cost effectiveness––a criterion for the selection of grinding media for wet milling in mineral processing operations

Experiments to evaluate the milling performance, hence the relative cost effectiveness index of selected grinding media were conducted in a laboratory scale ball mill. The five types of grinding mill balls studied were eutectoid steel, low alloy steel, medium chromium cast iron, cast semi-steel and unalloyed white cast iron. The results obtained show that the heat-treated medium chromium cast iron ball possess a superior combination microstructure, wear resistance, and despite its high price per tonne, cost effectiveness.     

How to make constrained fuzzy arithmetic efficient

 In the standard fuzzy arithmetic, the vagueness of fuzzy quantities always increases. G. J. Klir [2, 3] suggests an alternative – the constrained fuzzy arithmetic – which reduces this effect. On the other hand, it significantly increases the complexity of computations in comparison to the classical calculus of fuzzy quantities. So far, little attention was paid to the problems of implementation of the constrained fuzzy arithmetic, especially to its computational efficiency. We point out the related problems and outline the ways of their solution. We suggest to decompose the whole expression, classify all its subexpressions with respect to their individual computational complexity and precompute the corresponding subresults according to this classification.     

A Dilatometry Study of the Austenitization and Cooling Behavior of Ductile Iron Meant for the Production of Austempered Ductile Iron (ADI)

An understanding of the kinetics of transformation during austenitization, cooling, and austempering of ductile iron is critical to achieving the desired microstructures and ultimately mechanical properties in austempered ductile iron (ADI). To this end, dilatometry experiments have been carried out to study the austenitization and cooling behavior of an unalloyed ductile iron. When a typical austenitization temperature of 900°C is used, unlike in steels, there is an initial expansion of the specimen, which levels off as the soaking time is increased. This occurs despite the fact that the temperature remains constant. This phenomenon, hitherto unreported, highlights the subtle differences between the austenitization of ductile irons and steels. The initial expansion is attributed to the increase in austenite lattice parameter, arising from the diffusion of carbon from the graphite nodules. The levelling off signals the saturation of austenite with carbon and can therefore be used as an indicator of the appropriate austenitization time. Studies of the cooling behavior of unalloyed ductile iron have also shown that the dilatometer can be used as a tool for determining the minimum cooling rates, which guarantee the formation of ausferrite during austempering. When ductile iron is appropriately heat-treated based on results from dilatometry studies, the mechanical properties obtained are typically superior and consistent.     

Fuzzy controllers with conditionally firing rules

Mamdani (1975) controller was successfully used in many applications. One of its interpretations is that it uses a fuzzy relation as an approximation of the desirable input-output correspondence. We analyze mathematical properties of Mamdani controller and notice that it has lower computational complexity when compared to the residuum-based controller. However, we show that in standard situations, both these fuzzy controllers do not represent the rule base properly in the sense of finding a solution to the related system of fuzzy relational equations. First, we consider the premises and consequents as typical inputs and outputs, and we want their correspondence to be kept. Next, we require that each normal input produces an output that bears nontrivial information. These two conditions appear to be almost contradictory to the previous controllers. We suggest a generalization of Mamdani controller which allows us to satisfy these requirements. The theory and experiments suggest that it performs better without any change of rule base and without a substantial increase of complexity     

Existence of states on quantum structures

Orthomodular lattices occurred as generalized event structures in the models of probability for quantum mechanics. Here we contribute to the question of existence of states (=probability measures) on orthomodular lattices. We prove that known techniques do not allow to find examples with less than 19 blocks (=maximal Boolean subalgebras). This bound is achieved by the example by Mayet [R. Mayet, Personal communication, 1993]. Although we do not finally exclude the existence of other techniques breaking this bound, existence of smaller examples is highly unexpected.