Experimental crack propagation and failure analysis of the first stage compressor blade subjected to vibration

This paper presents results of experimental vibration tests of the helicopter turbo-engine compressor blades. The blades used in investigation were retired from maintenance under technical inspection of engine. Investigations were conducted for selected undamaged blades, without existence of preliminary cracks or corrosion pits. The blades during experiment were entered into transverse vibration. The crack propagation process was conducted in resonance condition. During the fatigue test, the growth of crack was monitored. In the second part of work, a nonlinear finite element method was utilized to determine the stress state of the blade during vibration. In this analysis a first mode of transverse vibration were considered. High maximum principal stress zone was found at the region of blade where the crack occurred.     

Analytical Problems in the Investigation of Unsaturated Acids Conversion II: Determination of Position Isomers,Conjugated Unsaturated Bonds and Composition of Fatty Acids

The paper discusses the methods of determination of the position of unsaturated bonds in a chain of acids, the determination of the sum of conjugated unsaturated bonds and the composition of the fatty acids. The position of unsaturated bonds in acids of modified oils may be determined most quickly by the method of pyrrolidide derivatives and determinations by the GLCMS method. The content of conjugated bonds had been determined by standardized method of UV spectrometry, and the composition of the fatty acids had been determined by gas chromatography.     

Comparison of volatiles emitted by male caribbean and mexican fruit flies

Volatiles emitted byAnastrepha suspensa andAnastrepha ludens males were trapped and compared by GC-MS. Both species emitted previously reported nine-carbon alcohols, (Z)-3-nonenol and (Z,Z)-3,6-nonadienol, and epimeric lactones, anastrephin and epianastrephin. A third isomeric lactone, the macrolide suspensolide, which was previously known only fromA. suspensa is reported here for the first time in the volatiles ofA. ludens. We also report that both species released different proportions of the same three sesquiterpene hydrocarbons:-farnesene,-bisabolene, and-trans-bergamotene. The-bisabolene was isolated in sufficient quantity fromA. suspensa volatiles to establish its absolute configuration as the (R)-(+)-enantiomer. Some plausible biosynthetic relationships of farnesol to the isoprenoid lactones and sesquiterpenes identified in this study are discussed. Finally, we report thatA. suspensa produces the monoterpene (Z)--ocimene whileA. ludens volatiles contained limonene.     

Framework for the integrated video quality assessment

Through years of development Content Networks (CN) have become more sophisticated and more technically diverse. Modern CN are designed to be more adaptive to communication environment, devices and user requirements. However, one open issue is the still fluctuating quality of service provision. As a result user experience can be negatively affected. In order to maintain a satisfactory level of user experience it is crucial to develop a feasible solution to measure the extent to which video services meet users?? expectation. Assessing video quality with respect to users?? subjective opinions is a complex task. In this paper we address challenges of this task and design an integrated framework using a number of comprehensive functional modules. Our framework integrates objective quality assessment models of Artifacts Measurement (AM) and Quality of Delivery (QoD) approaches. Only the fittest models are activated by the framework considering requirements of individual evaluation tasks. We also introduce our recent work of realising key functional modules of the framework. Joint subjective experiments between two institutes have also been carried out for the purpose of model implementation and evaluation. Results from experiments verify the concept of an integrated framework and show the effectiveness of its key modules in estimating the quality level of video services.     

Natural Micas Intercalated with Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Modified with Transition Metals as Catalysts of the Selective Oxidation of Ammonia to Nitrogen

Natural cationic layered clays—vermiculite and phlogopite—pretreated with acids were intercalated with alumina pillars. In next step, transition metals were deposited on the surface of pillared interlayer clays (PILC) by a liquid ion exchange method. The catalyst samples were characterized with respect to: composition (EPMA), structure (XRD), texture (BET), surface acidity (NH₃-TPD) and coordination of deposited transition metals (UV–vis-DRS). The modified clays were tested in the role of catalyst for the selective oxidation of ammonia to nitrogen. In a series of the studied samples the best catalytic performance presented alumina pillared vermiculite modified with copper.     

Triple-functional riboflavin-based molecule for efficient atom transfer radical polymerization in miniemulsion media

Triple-functional riboflavin-based macromolecule was synthesized providing an efficient activator regeneration by electron transfer atom transfer radical polymerization of butyl acrylate in a miniemulsion media in a fully oxygen tolerant environment. For the first time, the riboflavin-inspired supramolecular structure fulfilled three primarily roles, acting simultaneously as (a) an initiator due to incorporation of bromine molecules in a ribitol tail by esterification reaction of riboflavin with α-bromoisobutyryl bromide; (b) a reducing agent caused by the preservation of redox functionality of isoalloxazine ring in this structure; (c) and enables polymerization in air conditions. Electrochemical characterization of the riboflavin-based molecule was conducted by a series of cyclic voltammetry measurements, determining an activation rate constant (k_a = [1.34 ± 0.58] × 10³ M⁻¹ s⁻¹) reflecting a reduction of the copper(II) catalytic complex in the presence of the multifunctional initiator. Proposed reaction system allowed to maintain control during polymerization proved by linear kinetics and a clear shift in molecular weights, resulting in the preparation of polymer brushes with narrow molecular weight distribution (M_w/M_n = 1.39) with high initiation efficiency (ƒ_i = 72%).     

Theoretical and practical aspects of tube sinking by a rotary die

This paper is concerned with a method of analyzing the process of tube sinking by a rotary die, modifying the method of finite elements. The components of the state of strain tensor have been determined for the conventional tube sinking process as well as a rotary die. It has been proved that the adoption of a rotary die does not essentially change the scheme of the state of strain, but that it does, however, reduce the drawing force. The results of theoretical analysis have been compared with those of experimental tests effected by means of a special device ensuring die rotation.     

Compendium About Multicomponent Interdiffusion in Two Dimensions

Interdiffusion between dissimilar solids can change the properties of joined materials. Although much work has been done to study experimentally and theoretically interdiffusion in one-dimensional (1-D) diffusion couples, studying interdiffusion in two-dimensional (2-D) or three-dimensional (3-D) solids remains a challenge. In this article, we report an experiment and develop a model to study interdiffusion in a multicomponent system of 2-D geometry. The results (concentration maps and profiles) are compared with data obtained by modeling and numerical simulations. It is assumed that the system satisfies Vegard’s rule and diffusion coefficients are composition dependent. To model the multidimensional diffusion with a drift, we take benefit of the concept of the drift potential. A nonlinear parabolic-elliptic system of strongly coupled differential equations is formulated and the implicit difference method, preserving Vegard’s rule, is applied in the simulations.

     

Pillared smectite modified with carbon and manganese as catalyst for SCR of NOx with NH3. Part II. Temperature‐programmed studies

Temperature‐programmed desorption (TPD) and surface reaction (TPSR), and additionally FTIR spectroscopy of adsorbed NO molecules were used to characterise surface sites on pillared smectites modified with carbon and manganese. Much higher adsorption of NH₃ than NO was found, but acidic pre‐treatment increased NO sorption to comparable values as well as catalytic performance in SCR of NO_x. In this case formation of strongly bound NO₃ ⁻ species was recognised, which reacted with NH₃ at a temperature 200 °C higher than weaker adsorbed NO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Selective catalytic reduction of NO with ammonia over porous clay heterostructures modified with copper and iron species

Porous clay heterostructures (PCH), obtained on the basis of synthetic saponite, were modified with copper and iron ions by an ion-exchange method and tested as catalysts for the selective reduction of NO with ammonia (NH₃-SCR). Transition metal ions were introduced into H⁺ and NH₄⁺ forms of PCH. The catalysts were characterized with respect to their texture (BET), composition (EPMA), coordination of transition metals (UV–vis-DRS) and surface acidity (FT-IR, NH₃-TPD). The PCH-based catalysts have been found to be active, selective and stable in the NH₃-SCR process. The Cu-containing catalysts effectively operated at temperatures significantly lower than the Fe-modified samples. The catalyst obtained by exchanging copper ions in the ammonium form of PCH was considerably more active compared to the sample obtained from H⁺-PCH.