Microsegregation in nodular cast iron and its effect on mechanical properties

A review of the literature pertaining to the mechanical properties, solidification and segregation effects in nodular cast iron has been made. A series of investigations concerning the influence of microsegregation on mechanical properties of :pearlitic, ferritic and austenitic nodular cast iron have then been reported. The influence of section size on the tensile and impact properties of cornmercial purity and refined ferritic nodular cast iron has been studied. It has been shown. that an increase in section caused a decrease in impact transition temperature of the commercial purity material without greatly affecting the impact transition temperature of the purer material. This effect has been related to increased amounts of segregation effects such as cell boundary carbides in heavier sections of the commercial purity material. Microsegregation studies on the materials used in this thesis have been carried out using an electron probe microanalyser. This technique has shown that concentrations of chromium and manganese and depletions of nickel and silicon occurred at eutectic cell boundaries in nodular cast iron and were often associated with brittle carbides in these areas. These effects have been shown to be more prevalent in heavier sections. The nature of segregation during the solidification of nodular cast iron has been studied by quenching samples of nodular iron during the solidification process. Micro-analysis of such samples has shown that segregation of manganese and chromium occurs by a gradual build-up of these elements at the solid/liquid interface. The microstructures of the quenched specimens revealed carbide filaments connecting graphite nodules and areas of quenched liquid. These filaments have been used as evidence for a revised hypothesis for the solidification of nodular cast iron by a liquid diffusion mechanism. A similar series of experiments has been carried out on two high nickel austenitic irons containing 0.5 per cent manganese and 4 per cent manganese respectively. In both these materials a decrease in elongation was experienced with increasing section. This effect was more drastic in the 4 per cent manganese material which also contained much greater amounts of cell boundary carbide in heavy sections. Micro-analysis of samples of the 4 per cent manganese material quenched during solidification revealed that manganese concentrated in the liquid and that nickel concentrated in the solid during solidification. No segregation of silicon occurred in this material. Carbide filaments appeared in the microstructures of these specimens. A discussion of all the above effects in terms of current concepts is included.

Symbolic use of export information:a multidimensional conceptualisation, its' effect on performance and key antecedents

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Ash control methods to limit biomass inorganic content and its effect on fast pyrolysis bio-oil stability

This research investigates specific ash control methods to limit inorganic content within biomass prior to fast pyrolysis and effect of specific ash components on fast pyrolysis processing, mass balance yields and bio-oil quality and stability. Inorganic content in miscanthus was naturally reduced over the winter period from June (7.36 wt. %) to February (2.80 wt. %) due to a combination of senescence and natural leaching from rain water. September harvest produced similar mass balance yields, bio-oil quality and stability compared to February harvest (conventional harvest), but nitrogen content in above ground crop was to high (208 kg ha.-1) to maintain sustainable crop production. Deionised water, 1.00% HCl and 0.10% Triton X-100 washes were used to reduce inorganic content of miscanthus. Miscanthus washed with 0.10% Triton X-100 resulted in the highest total liquid yield (76.21 wt. %) and lowest char and reaction water yields (9.77 wt. % and 8.25 wt. % respectively). Concentrations of Triton X-100 were varied to study further effects on mass balance yields and bio-oil stability. All concentrations of Triton X-100 increased total liquid yield and decreased char and reaction water yields compared to untreated miscanthus. In terms of bio-oil stability 1.00% Triton X-100 produced the most stable bio-oil with lowest viscosity index (2.43) and lowest water content index (1.01). Beech wood was impregnated with potassium and phosphorus resulting in lower liquid yields and increased char and gas yields due to their catalytic effect on fast pyrolysis product distribution. Increased potassium and phosphorus concentrations produced less stable bio-oils with viscosity and water content indexes increasing. Fast pyrolysis processing of phosphorus impregnated beech wood was problematic as the reactor bed material agglomerated into large clumps due to char formation within the reactor, affecting fluidisation and heat transfer.

Formant-frequency variation and its effects on across-formant grouping in speech perception

How speech is separated perceptually from other speech remains poorly understood. In a series of experiments, perceptual organisation was probed by presenting three-formant (F1+F2+F3) analogues of target sentences dichotically, together with a competitor for F2 (F2C), or for F2+F3, which listeners must reject to optimise recognition. To control for energetic masking, the competitor was always presented in the opposite ear to the corresponding target formant(s). Sine-wave speech was used initially, and different versions of F2C were derived from F2 using separate manipulations of its amplitude and frequency contours. F2Cs with time-varying frequency contours were highly effective competitors, whatever their amplitude characteristics, whereas constant-frequency F2Cs were ineffective. Subsequent studies used synthetic-formant speech to explore the effects of manipulating the rate and depth of formant-frequency change in the competitor. Competitor efficacy was not tuned to the rate of formant-frequency variation in the target sentences; rather, the reduction in intelligibility increased with competitor rate relative to the rate for the target sentences. Therefore, differences in speech rate may not be a useful cue for separating the speech of concurrent talkers. Effects of competitors whose depth of formant-frequency variation was scaled by a range of factors were explored using competitors derived either by inverting the frequency contour of F2 about its geometric mean (plausibly speech-like pattern) or by using a regular and arbitrary frequency contour (triangle wave, not plausibly speech-like) matched to the average rate and depth of variation for the inverted F2C. Competitor efficacy depended on the overall depth of frequency variation, not depth relative to that for the other formants. Furthermore, the triangle-wave competitors were as effective as their more speech-like counterparts. Overall, the results suggest that formant-frequency variation is critical for the across-frequency grouping of formants but that this grouping does not depend on speech-specific constraints. © Springer Science+Business Media New York 2013.

Effects of ball-milling on PLGA polymer and its implication on lansoprazole-loaded nanoparticles

PLGA is a biodegradable polymer utilised widely in pharmaceutical research for the encapsulation of a wide range of drugs as nano particulate systems. This study investigates the impact of rotary ball milling on the physical properties of PLGA and its influence on nanoparticle formation prepared using the solvent displacement technique. By applying mechanical stress to the polymer and altering its physical appearance and molecular weight, the loading of lansoprazole within the nanoparticles was increased to 96%, with a reduction in particle size. The results indicate that rotary ball milling significantly reduces particle size, increases lansoprazole loading and improves the release profile for lansoprazole loaded PLGA nanoparticles.

Reactor design and its impact on performance and products

This chapter discusses engineering design and performance of various types of biomass transformation reactors. These reactors vary in their operating principle depending on the processing capacity and the nature of the desired end product, that is, gas, chemicals or liquid bio-oil. Mass balance around a thermal conversion reactor is usually carried out to identify the degree of conversion and obtain the amount of the various components in the product. The energy balance around the reactors is essential for determining the optimum reactor temperature and the amount of heat required to complete the overall reactions. Experimental and pilot-plant testing is essential for proper reactor design. However, it is common practice to use correlation and valid parameter values in determining the realistic reactor dimensions and configurations. Despite the recent progress in thermochemical conversion technology, reactor performance and scale up potential are the subjects of continuing research.

High stability multiplexed fibre interferometer and its application on absolute displacement measurement and on-line surface metrology

We propose a self-reference multiplexed fibre interferometer (MFI) by using a tunable laser and fibre Bragg grating (FBG). The optical measurement system multiplexes two Michelson fibre interferometers with shared optical path in the main part of optical system. One fibre optic interferometer is used as a reference interferometer to monitor and control the high accuracy of the measurement system under environmental perturbations. The other is used as a measurement interferometer to obtain information from the target. An active phase tracking homodyne (APTH) technique is applied for signal processing to achieve high resolution. MFI can be utilised for high precision absolute displacement measurement with different combination of wavelengths from the tuneable laser. By means of Wavelength-Division-Multiplexing (WDM) technique, MFI is also capable of realising on-line surface measurement, in which traditional stylus scanning is replaced by spatial light-wave scanning so as to greatly improve the measurement speed and robustness. © 2004 Optical Society of America.

Keyboard warriors in cyberfights:conflict in online communities of consumption and its effects on community resources

Conflicts are very common in Online Consumption Communities (OCC) and numerous expressions have developed to describe them. Prior research indicates contradictory effects on community resources, namely social capital and culture. One stream finds that online conflict dissolves social capital and community culture (cf. De Valck 2007) while another stream finds it enhances them (cf. Ewing, Wagstaff, and Power 2013). Therefore, the effect of OCC conflict on community resources is unclear. In this paper, we (1) investigate conflict in OCC to develop a typology, and (2) delineate how each type of OCC conflict impacts community resources. This research contributes to our understanding of OCC conflicts and to the literature on value formation in OCC.

Implementation of a machine tool performance measurement and diagnostic system and its impact on parts verification

Five axis machine tools are increasing and becoming more popular as customers demand more complex machined parts. In high value manufacturing, the importance of machine tools in producing high accuracy products is essential. High accuracy manufacturing requires producing parts in a repeatable manner and precision in compliance to the defined design specifications. The performance of the machine tools is often affected by geometrical errors due to a variety of causes including incorrect tool offsets, errors in the centres of rotation and thermal growth. As a consequence, it can be difficult to produce highly accurate parts consistently. It is, therefore, essential to ensure that machine tools are verified in terms of their geometric and positioning accuracy. When machine tools are verified in terms of their accuracy, the resulting numerical values of positional accuracy and process capability can be used to define design for verification rules and algorithms so that machined parts can be easily produced without scrap and little or no after process measurement. In this paper the benefits of machine tool verification are listed and a case study is used to demonstrate the implementation of robust machine tool performance measurement and diagnostics using a ballbar system.

The Methodology of the Subsistence Minimum Calculation for Developing Countries and its Computation on the Georgian Example

This article shows the social importance of subsistence minimum in Georgia. The methodology of its calculation is also shown. We propose ways of improving the calculation of subsistence minimum in Georgia and how to extend it for other developing countries. The weights of food and non-food expenditures in the subsistence minimum baskets are essential in these calculations. Daily consumption value of the minimum food basket has been calculated too. The average consumer expenditures on food supply and the other expenditures to the share are considered in dynamics. Our methodology of the subsistence minimum calculation is applied for the case of Georgia. However, it can be used for similar purposes based on data from other developing countries, where social stability is achieved, and social inequalities are to be actualized. ACM Computing Classification System (1998): H.5.3, J.1, J.4, G.3.

A dual definition for the factor content of trade and its effect on factor rewards in US manufacturing sector

We introduce a dual definition of the Factor Content of Trade (FCT) using the concept of the Equivalent Autarky Equilibrium. Estimating a symmetric normalized quadratic revenue function for the U.S. manufacturing sector between 1965 and 1991, we find that the FCT for capital is positive, while the FCT for skilled and unskilled labor is negative, suggesting that the Leontief Paradox is not present. Then the growth rate of the factor rewards is decomposed to the FCT, endowments, and technological change effects. We find that technological change is the most important determinant in explaining wage inequality between skilled and unskilled labor.

Brand personality complementatity:its effects on evaluations of extremely incongruent extensions

Prior research on brand extension has provided little evidence on enhancing the evaluation of extremely incongruent extension. Adopting the theoretical framework of schema congruity theory, the author posits that evaluations can be improved if brand personality impressions of both parent brand and extension are complementary. The author coins this as the brand personality complementarity (BPC) principle. Prior to examining BPC effect, cultural-specific brand personality scale was developed to identify universal and indigenous brand personality dimensions. The reason is BPC requires a reliable and valid brand personality scale in order to detect its effect. Following successful identification of the cultural-specific brand personality scale, a total of three experimental studies were done to investigate BPC effect. Specifically, one experimental study identified complementary levels amongst brand personality dimensions, whereas two experimental studies investigated the moderating effect of BPC. Findings from the scale development study reveal that Malaysian brand personality (MBP) scale is a second higher-order factor reflected by first higher-order factors of sophistication, youth, competence, and sincerity. Most importantly, findings from the experimental studies revealed; 1) different BPC levels amongst all possible pairs of MBP dimensions, 2) significant interaction effect of brand extension congruity x BPC, and 3) significant mediation effect of complementarity resolution. Specific findings indicated that when iv text-based stimuli were used to form brand personality impression, even low BPC level improves the evaluations of extremely incongruent extension. However, when visualbased stimuli were used, low BPC level worsen the extension evaluation compared those of the control condition (i.e. without brand personality impression). Implications for both academician and practitioner are discussed.

A magyar minimálbér-szabályozás és hatása a foglalkoztatásra, különösen 2000-től napjainkig (Minimum-wage regulation in Hungary and its impact on employment, with particular respect to the 2000’s)

Noha az 1990-es évek első felében felbomlott az akadémiai közgazdászok sok évtizeden át örök érvényűnek hitt közmegegyezése a minimálbér szükségképpen negatív foglalkoztatási hatásáról, a túlságosan magas minimálbért minden közgazdász foglalkoztatáscsökkentő hatásúnak jósolja. Tanulmányunkban a magyar minimálbér-szabályozást e hatás szempontjából vizsgáljuk és értékeljük. / === / Although the long-held view of an unambiguously negative employment effect of a binding minimum wage was challenged by empirical findings in the early 1990’s, it is unanimously predicted that if the minimum wage is set too high it will bring about adverse employment effects. Accordingly, our study starts from an evaluation of the magnitude of the Hungarian minimum wage, i.e., of how it relates to minimum wage rates elsewhere, and of how it has developed through time. Next we inspect the main features that characterize the Hungarian system of minimum wage regulation. Theoretical views on the potential employment effect of minimum wage regulation are then surveyed and contrasted to empirical findings. The study concludes by policy recommendations. To sum up the main strand of arguments, we try to demonstrate that even though Hungary’s minimum wage, if assessed by its ratio to average and/or median full-time earnings, does not appear particularly high by international standards, it might rightly be regarded as unreasonably high in light of Hungary’s excessively low relative rate of employment among the least schooled. This diagnose should become particularly evident once one takes into account that, in sharp contrast to established rules elsewhere, a significantly higher wage floor is in effect for those with lower secondary schooling. Abolition of this legally guaranteed premium over the minimum wage as well as more moderation in minimum wage adjustments are thus highly recommended.