A RHEOMETER FOR MEASURING THE PROPERTIES OF GRANULAR MATERIALS

ABSTRACT

A great many technological applications such as pneumatic handling of grains and minerals, drying of particles, gasification of solid fuels, require an understanding of the properties of granular solids. Material parameters which can describe the common phenomena exhibited by these granular materials, such as dilatancy, cohesion, adhesion, frictional resistance, etc. need to be incorporated in the model and methods devised for measuring and quantifying them. Reliable experiments are required to measure the properties of these materials. However, this branch of rheology has not been as well studied as the rheology of fluids due to the difficulties inherent to grannular materials in that they exhibit both solid-like and fluid-like properties. Here, we discuss the development of an instrument which can evaluate the material properties of grannular solids. Experimental investigations verify the commonly exhibited phenomena by these materials and estimate the various forces which are generated due to the flow of these materials, thereby enabling their characterization.     

A revised methodology for the determination of bulk material cohesion and adhesion

The determination of the wall liner properties and more importantly the flow properties of a bulk material is critical for the design of any bulk materials handling system. The design of such materials handling systems will be most effective when handling bulk materials at the physical properties they were designed to handle. Due to the fast-paced nature of expansion in the mining industry and demand of mineral resources, it is quite common for materials handling systems to handle bulk materials that were not intended for the system. Wet and Sticky Materials (WSM) within the materials handling stream can cause significant downtime, due to events such as blockages of bins, hoppers and transfer chutes, remains left in train wagons and dump trucks as well as conveyor belt carry back (Roberts, 2005; Connelly, 2011 [2]).WSM are problematic within the materials handling stream due to the inter-particle and boundary cohesion and adhesion forces. The current measurement techniques for WSM have limitations and new methods must be considered. The development of new testers that can measure the wall adhesion and inter-particle adhesion of a bulk material can give a quantitative value for the adhesion present in a bulk material sample. The following paper will present a revised methodology for the estimation of the adhesion of bulk materials determined from the extrapolation of the Instantaneous Yield Locus (IYL). The predicted adhesion values from this methodology will be compared to experimental measurements using an inter-particle adhesion tester.     

Carbon nanomaterials based on plant biopolymers as radionuclides sorbent

Abstract

The technogenic human activities associated with the operation of nuclear power facilities lead to the contamination of natural water bodies and soils with radioactive substances, including heavy radionuclides, such as uranium and thorium. Purification of natural water bodies is a pressing environmental issue. A study of the adsorption capacity for heavy U²³⁸ and Th²³² radionuclides by the samples of new carbon nanomaterials was conducted. Nanocarbon materials was synthesized based on vegetal polymers, such as technical lignin, starch and from lignocellulosic material—the bark. It was established that the investigated samples have different sorption indices in relation to radionuclides, which is determined by their chemical composition, as well as by the surface-capillary properties of carbonized materials. It is shown that the content of mobile and fixed forms of radionuclides on the investigated sorbents are significantly different. High sorption capacity of the carbonated lignin sample with respect to uranium are shown. A sample of nanocarbon materials synthesized based on the lignocellulosic complex of the bark exhibits high sorption properties in relation to thorium. The possibility of using the carbonic nanomaterial as the sorbents of radionuclides is shown.     

A novel method to measure the porosity of porous materials

ABSTRACT

Porosity is the single most important feature of porous materials. On the basis of the research work, a new method to measure the porosity of porous materials is proposed in this paper. This method is a system of equations composed of six formulas, so it is called model equation method. It is not only applicable to space holder technique but also applicable to metal prepared by pure powder metallurgy. Compared with mass volume method and immersion medium method, our new method is more simple and efficient. More importantly, it can be used as a standard measure. This study provides a fundamental basis for the measurement of porosity in porous materials.     

Performance characteristics of an apparatus based on the curve-fitting method for measuring thermal properties at cryogenic temperatures

This paper describes the performance characteristics of a new test apparatus and the measured results using the apparatus. It has been developed on the basis of Harmathy's curve-fitting method to measure, in a short time, the physical properties of the nonmetallic materials for a cryogenic storage tank. The apparatus has been used to measure the heat capacity, thermal conductivity, and thermal diffusivity of the materials at the same time in the temperature range of approximately ?180°C to +50°C.With this apparatus the thermal conductivity can be measured over a wide range of approximately 0.01 kcal m^?1 h^?1°C^?1 to 10 kcal m^?1 h^?1°C^?1 in the range of ?180°C to +50°C. The materials investigated were structural materials such as concrete, wood, frozen soil, and autoclaved lightweight concrete (ALC) and such insulation materials as calcium silicate, phenolic foam, and polyurethane foam.     

Benefit of Modern Arc Management in MF Dual Magnetron Sputtering Power Supplies

For modern large area coatings reactive dual magnetron sputtering (DMS) is a widespread technology. Economic constraints and advanced technology calls for increasing process flexibility regarding target utilization as well as the use of new materials. This in turn raises demands to the arc handling capabilities of the power supplies. On the one hand, a stable process at high arcing rates demands short arc blanking times and fast recovery to full output power. On the other hand, some materials tend to the formation of so‐called “hard” arcs, with hot cathode spots. In this case, longer treatment times are needed. The benefit of modern arc handling capabilities is demonstrated for reactive SiO₂ deposition from heavily used targets. For other demanding materials with low melting point, favourable operating modes are investigated.     

Analysis of Preparation of Dextran Hydrogel Membranes as a Wound Dressing

Abstract

Several variables which could affect the polymerization and physico-chemical properties of dextran hydrogel were investigated. The dextran hydrogels were prepared at multiple level of each variable. Water uptake capacity and handling characteristics were employed to evaluate the hydrogels. The effect of each variable on the polymerization of dextran is discussed and an optimum formulation of dextran hydrogel is presented.     

Modelling precipitation sequences in powerplant steels Part 2 – Application of kinetic theory

Abstract

New kinetic theory capable of dealing with the simultaneous precipitation of several phases has been applied to a variety of creep resistant power plant steels. It has been demonstrated that the model has the ability to predict the vast differences in precipitation kinetics reported in the published literature for power plant steels. New experimental results on precipitation in a 9Cr 1Mo type steel are reported and shown to be consistent with theoretical predictions.     

Certainty preference and the Arrow-Pratt measure

Abstract. In Schmidt (1998) a new axiomatic model of decision making under risk has been developed, which can accommodate the certainty effect and is, apart from this property, equivalent to expected utility in all other choice problems. A central feature of this model, termed expected utility with certainty preference, is to allow for a measurement of the certainty effect analogously to the measurement of risk aversion by the Arrow-Pratt measure. The purpose of the present paper is to provide a complete characterization of certainty preference. Therefore, among other things, all standard concepts in the theory of risk aversion are defined and analyzed in the framework of certainty preference. This investigation reveals that the measurement of the certainty effect has the same theoretical capabilities as the measurement of risk aversion by the Arrow-Pratt measure. Additionally, expected utility with certainty preference is compared with the existing literature on non-expected utility models.     

Systemic principals of research of functional states of the gas-man operator while working in the desert

This work describes functional state of the gas-man operator while working in the desert. Under the functional state, one understands the state of the operator that is changing during the work shifts. The most important characteristics of the operator's functional state are work capacity and fatigue. These are two sides of the same coin. The more the fatigue is, the less is the work capacity. In spite of the broad interest to these phenomena, ther is still not a precise and reliable way to measure them. The present article focuses on some aspects of this important issue from the activity theory point of view.     

Modelling of dealumination of aluminium silicate molecular sieves

Abstract

A simplified treatment of the dealumination of aluminium silicate (zeolite like) molecular sieves has been developed that considers both the diffusion of aluminium atoms and the formation and migration of vacancy sites. The instantaneous concentration of aluminium atoms as a function of time and location has been derived according to Fick's second law. Critical parameters affecting the dealumination process are discussed. The calculated results agree with the ratios of silicon to aluminium reported in the literature from infrared and ²⁷Al NMR spectroscopy studies on the commercial aluminium silicate molecular sieves materials Mordenite and ZSM-5, following exposure to air and water vapour.     

Cation exchange applications of synthetic tobermorite for the immobilization and solidification of cesium and strontium in cement matrix

Immobilization and solidification of hazardous cations like Cs¹³⁷ and Sr⁹⁰ are required while handling the radioactive waste of nuclear power plants. Efforts are on to find a fail proof method of safe disposal of nuclear wastes. In this context, various materials like borosilicate glass, zeolites, cements and synthetic rocks have been tried by several workers. This communication deals with the synthesis, characterization, cesium uptake capacity and leaching behaviour of synthetic alumina-substituted calcium silicate hydroxy hydrate, which are close to that obtained for the natural mineral,11 Å tobermorite. The synthetic mineral show cation selectivity for Cs⁺ in presence of500–1000 times concentrated solutions of Na⁺, K⁺, Mg⁺, Ca²⁺, Ba²⁺ and Sr²⁺. Although the ordinary portland cement (OPC) which is often used in waste management operations alone holds negligible amounts of Cs⁺ and Sr²⁺, the addition of alumina-substituted tobermorite to OPC enhances the retention power of cement matrix by drastically lowering the leach rate of cations     

On the Power Handling Properties of High Temperature Superconducting Microwave Contiguous Duplexer

The power handling properties of a high temperature superconducting (HTS) microwave contiguous duplexer are measured in this letter. The HTS contiguous duplexer was fabricated using YBa₂Cu₃O₇ (YBCO) thin films on a 0.5-mm-thick LaA1O₃ substrate, operation frequencies of which are centered at 3.25 GHz and 3.75 GHz with 500-MHz-wide channels. The tested frequency response of power handling property of the HTS contiguous duplexer shows that there is a decreased power handling property on the crossover region; however, this microwave nonlinearity does not affect the engineering application of HTS contiguous duplexers and multiplexers.     

Intergroup Conflict Management Framework for Hong Kong's Manufacturing Industry

Abstract

An examination of 28 project leaders' and managers' opinions on conflict and conflict management practice in Hong Kong found that intergroup conflict is the most commonly experienced type of conflict, as more Hong Kong–based companies adopt a matrix or pseudo-matrix organizational structure. Although nearly 80% of the interviewees were not familiar with modern conflict management theory and practice as presented in contemporary literature, they tended to use what classic scholars in conflict management would call the “confrontation” mode in handling task-oriented conflict, and the “withdrawal” or “forcing” mode in handling emotion-oriented conflict. Short product development cycle time was found to have a very significant influence on the conflict management practices of contemporary project managers and project support personnel working in Hong Kong's manufacturing industry. We propose a conflict management framework based on our findings, and we discuss the concept of “cognitive-affective conflict.”     

Analytical estimates of the characteristics of surface plasmon resonance fibre-optic sensors

Abstract

In surface plasmon resonance (SPR) fibre-optic sensors, the optical power transmittance is important in determining behaviour. In this paper numerical calculations are used to estimate the optical power transmittance of SPR fibre-optic sensors. These analytical estimations can be applied in SPR fibre-optic sensors both with a transducing layer and without a transducing layer. The results of these numerical calculations agree well with previously published experimental results. This work will aid in the design of SPR fibre-optic sensors in terms of geometrical structure, materials and dynamic range as well as allowing the prediction of performance and of limitations of the design.     

Quick high-temperature hydrothermal synthesis of mesoporous materials with 3D cubic structure for the adsorption of lysozyme

Abstract

Three-dimensional cage-like mesoporous FDU-12 materials with large tuneable pore sizes ranging from 9.9 to 15.6 nm were prepared by varying the synthesis temperature from 100 to 200 °C for the aging time of just 2 h using a tri-block copolymer F-127(EO₁₀₆PO₇₀EO₁₀₆) as the surfactant and 1,3,5-trimethyl benzene as the swelling agent in an acidic condition. The mesoporous structure and textural features of FDU-12-HX (where H denotes the hydrothermal method and X denotes the synthesis temperature) samples were elucidated and probed using x-ray diffraction, N₂ adsorption, ²⁹Si magic angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy. It has been demonstrated that the aging time can be significantly reduced from 72 to 2 h without affecting the structural order of the FDU-12 materials with a simple adjustment of the synthesis temperature from 100 to 200 °C. Among the materials prepared, the samples prepared at 200 °C had the highest pore volume and the largest pore diameter. Lysozyme adsorption experiments were conducted over FDU-12 samples prepared at different temperatures in order to understand their biomolecule adsorption capacity, where the FDU-12-HX samples displayed high adsorption performance of 29 μmol g^?1 in spite of shortening the actual synthesis time from 72 to 2 h. Further, the influence of surface area, pore volume and pore diameter on the adsorption capacity of FDU-12-HX samples has been investigated and results are discussed in correlation with the textural parameters of the FDU-12-HX and other mesoporous adsorbents including SBA-15, MCM-41, KIT-5, KIT-6 and CMK-3.     

A reality check and tutorial on electrochemical characterization of battery cell materials: How to choose the appropriate cell setup

The ever-increasing demand for electrical energy storage technologies triggered by the demands for consumer electronics, stationary energy storage systems and especially the rapidly growing market of electro mobility boosts the need for cost-effective, highly efficient and highly performant rechargeable battery systems. After the successful implementation of lithium ion batteries (LIBs) in consumer electronics and electric vehicles, there is still a need for further improvements in terms of energy and power densities, safety, cost and lifetime. In the last decades, a large battery research community has evolved, developing all kinds of new battery materials, e.g., positive and negative electrode active materials for different cell chemistries, electrolytes, related auxiliary (inactive) materials and their constituents.Different battery cell setups, including so-called “half-cell”, “symmetrical-cell” and “full-cell” setups as well as two-electrode or three-electrode configurations, are described in the literature to be used in the laboratory for the electrochemical characterization of battery components like electrode materials and electrolytes. Typically, all cell setups display certain limitations or issues concerning their application for the parameter determination of battery materials. In this review article, we highlight the advantages but also the limitations of different cell setups, with special focus on two- and three-electrode configurations with or without the help of “auxiliary” excess capacity Li metal electrodes. We point out possible mistakes and/or misinterpretations and give the reader recommendations, i.e., a guide for the right choice of the cell setup/configuration appropriate for the intended aim of the electrochemical investigation.     

Development and application of a methodology for the measurement of corrosion and erosion damage in laboratory,burner rig and plant environments

Abstract

Fuel gases derived from solid fuels such as coal, biomass and waste and their mixes have the potential to cause both erosion and corrosion damage to components in gas turbines and diesel engines. To allow the statistically valid assessment of materials performance in short term plant runs, burner rig tests and laboratory simulated environments a methodology has been developed to collect compatible quantitative data on materials degradation. Accurate measurement techniques based on pre-exposure contact metrology and post-exposure optical microscopy/image analysis have been developed. These take into account both the low level of damage required for practical systems and the localised nature of hot corrosion damage. The data produced have been used to derive and test quantitative models for the prediction of the performance of candidate materials in such power systems. For these models to be used with confidence, similar damage morphologies must be produced in both the real and simulated conditions, as well as similar damage rates.     

Development of peening technique using recirculating shot accelerated by water jet

Abstract

The present paper demonstrates the development of a peening technique using recirculating shot accelerated by a water jet that can be used as a risk free treatment in power and chemical plants. Although it is important to increase the reliability of structural materials used in large scale structures, such as power and chemical plants, it is hazardous to treat these structures by general shot peening (SP) techniques because of the risk of sparks and dust explosions. In the present study, an SP technique using a water jet to accelerate shot has been developed, and the conditions under which it is used have been optimised in terms of nozzle geometry, standoff distance and amount of shot. In order to demonstrate the effect of SP, austenitic stainless steel Japan Industries Standards SUS316L was peened and evaluated in terms of its residual stress, fatigue strength and resistance to stress corrosion cracking.