Positron Study of Origin of Thermoelastic MartensiteStabilization for a Cu-Zn-Al Alloy

A series of Cu-23Zn-10Al (at pct) alloy specimens subjected to different heat-treatment processes have been studied by means of Doppler broadening technique of positron annihilation combined with mechanical test. Results show that the mechanism of quenched-in vacancies, instead of the other suggested ones, plays a dominant role in thermoelastic martensite stabilization of Cubased shape memory alloy. Knowing the character of the movement of quenched-in vacancies and eliminating them as rapidly as possible are the basis for further optimizing heat-treatment process to obtain desired shape memory performance     

Selected variants of a Memetic Algorithm for JSP – a comparative study

The article aims to address a research gap concerning the adequate configuration of a Memetic Algorithm adapted to solve the Job-Shop Scheduling Problem. The goal was accomplished by means of conducting a comparative study of 16 variants of a Memetic Algorithm, characterised with different places of hybridisation and local search methods applied. The study involved the solution of eleven instances of JSP and the comparison of the results with the results achieved with an Evolutionary Algorithm lacking the mechanism of hybridisation and selected local search methods. The utilitarian significance of the problem also involved the use of assessment measures intended for both practical applications and research purposes.     

Choice of a γ-emission source for phase analysis of a material by nuclear γ-resonance

Consideration is given to the influence of nonresonance attenuation of resonance -quanta by the lattice of a -emission source, on the shape of a monoline in the Mössbauer spectrum. It is shown that this effect leads to increased error in the phase analysis of a material in nuclear -resonance spectroscopy. Criteria are determined for the suitability of a -emission source for use in the phase analysis of materials by this method. The actuality of the problem is shown for the most widely used Mossbauer isotopes.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 55–57, June, 1994.     

Vapor-phase synthesis of a solid precursor for α-alumina through a catalytic decomposition of aluminum triisopropoxide

A new solid precursor, hydrous aluminum oxide, for α-alumina nanoparticles was prepared by thermal decomposition of aluminum triisopropoxide (ATI) vapor in a 500 mL batch reactor at 170-250 °C with HCl as catalyst. The conversion of ATI increased with increasing temperature and catalyst content; it was nearly complete at 250 °C with the catalyst at 10 mol% of the ATI. The obtained precursor particles were amorphous, spherical and loosely agglomerated. The primary particle size is in the range 50-150 nm. The ignition loss of the precursor was 24%, considerably lower than 35% of Al(OH)₃, the popular precursor for alumina particles. Upon calcination of the precursor at 1200 °C in the air with a heating rate of 10 °C/min and a holding time of 2 h, the phase was completely transformed into α. The spherical particles composing the precursor turned worm-like by the calcination probably due to sintering between neighboring particles. The surface area equivalent diameter of the resulting α-alumina was 75 nm.     

Construction of algorithm for calculation of the flow rate of a gas–liquid mixture in a horizontal pipeline for the microprocessor of an information measurement system

Features of an algorithm for calculation of the flow rate of the liquid phase of a gas–liquid mixture with the use of a variable pressure-drop flow meter with constricting devices are considered. Corresponding dependences for use in calculating the concentration of liquid in a mixture and a correction factor based on the readings of the flow meter for use in determining the flow rate of a single-phase flow are obtained.     

Arrhenius plot for a reaction catalyzed by a single molecule of β-galactosidase

The activity of a single enzyme molecule of Escherichia coli β-galactosidase was measured using a capillary electrophoresis continuous flow assay. As the enzyme molecule traversed the capillary the incubation temperature was increased from 27 to 37 °C, providing a continuous record of the change in rate with temperature. This data was used to develop a single enzyme molecule Arrhenius plot, from which the activation energy of the reaction was determined to be 31 kJ mol(-1).     

The Development of a Knowledgeable Monitoring System for Weapon Equipment

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The potential of knitting for engineering composites—a review

Current literature on knitted composites tends to address the aspects of manufacture and characterisation separately. This paper aims to bring together these two sets of literature to provide the reader with a comprehensive understanding of the subject of knitted composites. Consequently, this paper contains a detailed outline of the current state of knitting technology for manufacturing advanced composite reinforcements. Selected mechanical properties of knitted composites, and some of the predictive models available for determining them are also reviewed. To conclude, a number of current and potential applications of knitting for engineering composites are highlighted. With a comprehensive review of the subject, it is believed that textile engineers would be able to better understand the requirements of advanced composites for knitting, and, by the same token, composites engineers can have a better appreciation of the capability and limitations of knitting for composite reinforcement. This should lead to more efficient usage and expanded application of knitted composites.     

Dynamic Optimal Design for the Reliability of a Mechanical System

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An Analysis Method for Capability Reliability of a Thermal System

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Investigations of paper aging—a search for archive paper

The change of mechanical (folding endurance index, breaking stress, breaking length, breaking index, tear index ), optical (brightness), chemical (cold extract pH, alkali reserve) and physical (water absorbency by surface, smoothness) characteristics of 5 paper samples were measured during the accelerated aging at 105 ± 2°C, and the measured exponential dependencies were described and fitted by the formal first-order kinetics. The statistic parameters of such fitting calculations evidenced good agreement of the experimental and calculated data. The relative decrease of each paper property corresponding to 48 days of accelerated aging was evaluated in order to compare the durability of paper samples. The best aging resistance was obtained for paper MAESTRO® Classic (SCP Ruomberok, Slovak Republic) and this paper material may be recommended for archival applications.     

An Exploration of a New Running Mode of Equipment Management for Institutions of Higher Learning

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Woolrock—a material for technical use consisting of keratin

This article debates the production of mouldings made of keratin. It is demonstrated that the properties of keratin allow for being processed with heat and pressure to manufacture tough mouldings without chemical preprocessing of the used wool. This material thus has a high potential as a bioplastic, because it potentially can be used with conventional plastic manufacturing techniques. Additionally, it might also serve as an adhesive in various applications. The biobased material might become a sustainable source for mouldings.

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Design of a scheduling system for flexible manufacturing cells†

The objective of this paper is to describe an effective scheduling system for flexible manufacturing cells (FMC). Based on FMC characteristics, cell scheduling can be categorized for a dynamic, modified flow shop working in a real-time environment. A heuristic static cell scheduling methodology for minimizing mean flowtime is first proposed. This is then modified to allow dynamic cell scheduling to reflect the real-world situation of continuous job introduction to the cell. Computational results show that the proposed algorithms yield optimal or near optimal job sequences in a very short period of time, thus satisfying a real-time need of rapid computation.     

Implementation of design of experiments approach for the micronization of a drug with a high brittle–ductile transition particle diameter

Objective: To optimize air-jet milling conditions of ibuprofen (IBU) using design of experiment (DoE) method, and to test the generalizability of the optimized conditions for the processing of another non-steroidal anti-inflammatory drug (NSAID).

Methods: Bulk IBU was micronized using an Aljet mill according to a circumscribed central composite (CCC) design with grinding and pushing nozzle pressures (GrindP, PushP) varying from 20 to 110?psi. Output variables included yield and particle diameters at the 50th and 90th percentile (D₅₀, D₉₀). Following data analysis, the optimized conditions were identified and tested to produce IBU particles with a minimum size and an acceptable yield. Finally, indomethacin (IND) was milled using the optimized conditions as well as the control.

Results: CCC design included eight successful runs for milling IBU from the ten total runs due to powder “blowback” from the feed hopper. DoE analysis allowed the optimization of the GrindP and PushP at 75 and 65?psi. In subsequent validation experiments using the optimized conditions, the experimental D₅₀ and D₉₀ values (1.9 and 3.6?μm) corresponded closely with the DoE modeling predicted values. Additionally, the optimized conditions were superior over the control conditions for the micronization of IND where smaller D₅₀ and D₉₀ values (1.2 and 2.7?μm vs. 1.8 and 4.4?μm) were produced.

Conclusion: The optimization of a single-step air-jet milling of IBU using the DoE approach elucidated the optimal milling conditions, which were used to micronize IND using the optimized milling conditions.     

Development of a New Welding Material for Arc Welding of As-cast Ferritic Ductile Iron

Using the nickel welding wire, the effect of alloying elements on the chilling tendency of partial fusion zone (PFZ) of arc-welded ferritic ductile iron and the mechanical properties of weld metal have been systematically studied. On this basis a new nickel electrode for arc welding of ferritic ductile iron (QT400-17) is developed for the first time. The mechanical properties of its weld metal can match those of ferritic ductile iron. The width of carbide layer (WCL) in PFZ is significantly decreased, the welded joint has excellent machinability and the weid metal has high hot cracking resistance     

β-Cyclodextrin-induced fluorescence enhancement of a thermal-responsive azobenzene modified polydiacetylene vesicles for a temperature sensor

We devised a novel PDA-based model with linear temperature dependence of fluorescence intensity in a wide temperature range, which could be applied as an accurate temperature sensor in chemical or bio-environment due to the biocompatibility of polydiacetylene (PDA) vesicles. The fluorescence intensity was remarkably enhanced after the adding of β-cyclodextrin (β-CD), and the fluorescent signal remained linear proportional to the temperature in the range from 25 °C to 80 °C. Further, photo-controlled inclusion and exclusion reaction of the azobenzene-containing PDA vesicles with β-CD had been used to act as driving force to induce the change of fluorescence intensity for the composite vesicles. Fluorescence spectroscopy and fluorescence microscopy were used to characterize the fluorescence properties of system. Two-dimensional NMR was used to characterize the interaction between cyclodextrin and azobenzene functional groups. Our work provided a novel system that combines photo-chemistry and host–guest chemistry for a photo-stimulus-responsive vesicle and should be valuable in application in PDA-based temperature sensor.     

A Theoretical Study of the Pressure for Liquid Metal Infiltration of a Fiber Preform

A theoretical model has been established for calculating the infiltration pressure of metal melt into the preform of ceramic fibers according to the basic principle of hydromechanics. There are three forces acting on the infiltration process in the model, i.e. viscous friction, capillary force, and gravity The effects of the volume fraction of fibers (Vf) and infiltrating depth on the infiltration pressure are discussed. The results show that the infiltration pressure increases with the increase of fiber volume fraction and infiltration depth. There is a linear relationship between infiltration pressure and infiltiation depth. The effect of gravity on the infiltration pressure can be ignored     

A Method for Determining the Reliability Index of a Materiel Subsystem

This paper presents a method for determining the reliability index of a subsystem in the mate-riel demonstration phase-AHP Failure Rate Method.It fully considers the various factors which influ-ence a subsystem reliability index and solves a difficult problem that puzzles the demonstration person-nel.     

Development of a reduced-order model for large-scale Eulerian–Lagrangian simulations

Multiphase flows with solid particles are commonly encountered in various industries. The CFD–DEM method is extensively used to simulate their dynamical behavior. However, the application of the CFD–DEM method to simulate industrial-scale powder processes unavoidably leads to huge computational costs. With the aim of overcoming this issue, we propose a nonintrusive reduced-order model for Eulerian–Lagrangian simulations (ROM-EL) to efficiently reproduce gas–solid flow in fluidized beds. In the model, a Lanczos based proper orthogonal decomposition (LPOD) is newly employed to efficiently generate a set of POD bases. After the numerical snapshots are projected onto the reduced space spanned by the POD bases, a series of multidimensional functions of POD coefficients are constructed using a surrogate interpolation method. To demonstrate the effectiveness of this model, validation studies are performed based on the simulations of a fluidized bed. The macroscopic properties, such as the particle distribution, bed height, pressure drop, and distribution of bubble size, are shown to agree well in the CFD–DEM model and ROM-EL. Further, our proposed ROM-EL reduces the computational cost by several orders of magnitude compared with the CFD–DEM simulation. Accordingly, the ROM-EL could significantly contribute to the progress of modeling and simulation for industrial granular flows.