Grain size

Computer vision algorithms are natural candidates for high performance computing systems. Algorithms in computer vision are characterized by complex and repetitive operations on large amounts of data involving a variety of data interactions (e.g., point operations, neighborhood operations, global operations). In this paper, we describe the use of the custom computing approach to meet the computation and communication needs of computer vision algorithms. By customizing hardware architecture at the instruction level for every application, the optimal grain size needed for the problem at hand and the instruction granularity can be matched. A custom computing approach can also reuse the same hardware by reconfiguring at the software level for different levels of the computer vision application. We demonstrate the advantages of our approach using Splash 2-a Xilinx 4010-based custom computer.

The role of morphology in reading aloud was examined measuring naming latencies to pseudowords and words composed of morphemes (roots and derivational suffixes) and corresponding simple pseudowords and words. Three groups of Italian children of different ages and reading abilities, including dyslexic children, as well as one group of adult readers participated in the study. All four groups read faster

Silicon thin films grown near the boundary between the amorphous/microcrystalline growth offer superior properties for industrial applications. Series of silicon samples, in which crossing of this transition region was achieved by changing a single technological parameter (dilution of silane in hydrogen, deposition temperature, sample thickness) were used to test our model of transport, connecting the macroscopically observed transport properties and the crystallinity, hydrogen content, grain size and grain boundaries. Microscopic study by AFM led to the formulation of the geometrical model of growth of mixed phase Si. The demand for research of microcrystalline or polycrystalline silicon prepared at low substrate temperatures is stimulated by the use of cheap plastic substrates. In addition to a direct deposition an alternative technology, such as metal-induced crystallization supported by the electric field is discussed. Possible future application of thin silicon films, for example in a "nanolithography", is also shown. *

High-temperature creep tests were conducted on polycrystalline copper of commercial purity in order to investigate the inter-relationship between the extent and the rate of grain boundary sliding (GBS) and the development of internal cavitation. An image processing technique was used to provide quantitative information on the size and shape of the cavities formed over a range of stresses and at temperatures from 673 to 873 K. The results demonstrate that cavity development is inhomogeneous within any specimen, such that there is an increase in the level of cavitation in regions of higher local strain. It is shown by quantitative measurements that the total cavitated area increases at the faster sliding rates, but the number density of cavities decreases at the highest sliding rates because of cavity interlinkage. When interlinkage is taken into account, the results confirm that the overall level of cavitation is related to the occurrence of GBS.

We investigated the sediment-related distribution of both nematodes and macrofauna on the Belgian part of the North Sea (Southern Bight of the North Sea) in order to evaluate whether both faunal groups reflect similar patterns in community composition and diversity. Fine-grained sediments (median grain size <200 mm) were inhabited by nematode communities characterised by a low diversity and dominated by non-selective deposit-feeding nematodes. Nematode communities from coarser sediments were significantly different in terms of community composition and diversity. Moreover, all nematode feeding types were present in coarser sediments. These differences were explained by the contrasting biogeochemical processes prevailing in both sediment types, rather than granulometry and food availability per se. Macrofaunal distribution patterns were different from those of the nematode communities and seem to be related to water column processes (SPM loading, food availability, hydrodynamic stress) that promote the establishment of diverse communities in the coarser sediments but not in the finest sediments. This suggests that data on nematodes and macrofauna reveal different, complementary aspects of the factors structuring the benthic ecosystem that can be of importance in assessing the ecological status of the seafloor.

Field research was conducted on the effects of different mulching materials on the yield of Quantity protein maize which include polythene sheet, dry grasses and control. The different mulching materials were tested on nine (9) ridges each measuring 10m. The research was laid out in a completely randomized block design each treatment replicated three times. The parameters measured include weight of cobs, weight of 100grain, and total grain, there was no statistical difference in the weight cobs among all the treatments, similarly, there was also no statistical different in the weight of 100 grain. As far the weight of grain per 5m 2 there was a significant difference among the treatments with polythene sheet covered plots that have 0.25kg, however, the grass-mulched plots 0.16kg was statistically similar to the control plots 0.15kg. And finally for store weight observed per 5m 2 , polythene sheet covered plots were significantly higher than grass-mulched plots which are also significantly different to control plots with the values of 1.23kg, 1.21kg and 0.71kg respectively.

The salient characteristics of martensite formation kinetics in 9Cr-1W-0.23V-0.063Ta-0.09C-0.02N (wt.%) reduced activation steel have been investigated using differential scanning calorimetry and supplemented by microscopy characterisation. Accurate determination of the martensite start (M S) and finish (M f) temperatures as a function of cooling rate (1-99 K min À1) and holding time (1-120 min) in the c-austenite phase field have been made. The critical cooling rate to form nearly 100% martensite is found to be of the order of 5-6 K min À1. The measured latent heat for the martensite transformation is found to be in the range 62-75 J g À1. In the case of austenitisation at 1323 K, it is found that the grain size of the parent austenite exhibited significant growth and the observed M S temperature too exhibited a systematic increase with austenite grain size. However, for those samples that are solution treated at a slightly lower temperature of 1253 K, the M S is found to be initially insensitive to the increase in holding time for up to about 30 min. This trend is followed later on by the usual increasing character of M S for further rise in the holding periods, up to about 120 min. This unusual initial behaviour is also reflected by the corresponding variation in the hardness values of the quenched in martensite. Moreover, the growth of parent austenite grains has also been restricted during the initial phase of solution annealing at 1253 K. This is attributed to the presence of undissolved carbide particles, which exert a pinning influence on the movement of austenite grain boundaries. The observed athermal martensite formation kinetics is described well by the Koistinen-Marburger relation.

Positive correlations between plant height and grain yield have been reported for sorghum. The introduction of stay-green in sorghum, and the associated reduction in lodging, has opened the possibility to exploit this positive association. The aim of this study was to analyse the direct effects of the dwarfing gene dw3 (and therefore plant height) on shoot biomass, grain yield, and yield components in pairs of 3-dwarf genotypes and their isogenic 2-dwarf tall mutants. Isogenic pairs with different genetic backgrounds were grown in three field experiments under nutrient and water non-limiting conditions. Tall mutants were significantly taller and produced more shoot and stem biomass than their shorter counterparts. Generally, tall types yielded more grain than short types, but significant interactions between experiment, genetic background and stature affected the consistency of the results. dw3 only affected grain size and not grain number. Increased grain mass of tall types was associated with significantly greater stem mass per grain at anthesis and greater shoot biomass per grain accumulated between anthesis and maturity. The increased biomass of tall plants was therefore important for increased grain yield under optimum conditions. Potential implications of increased biomass production for drought adaptation are discussed.

Adaptive thin-film nanocomposite coatings comprised of crystalline ductile phases of gold and molybdenum disulfide, and brittle phases of diamond like carbon (DLC) and ytrria stabilized zirconia (YSZ) have been investigated by specialized microstructurally based finite-element techniques. One of the major objectives is to determine optimal crystalline and amorphous compositions and behavior related to wear and durability over a wide range of thermo-mechanical conditions. The interrelated effects of microstructural characteristics such as grain shapes and sizes, local material behavior due to interfacial stresses and strains, varying amorphous and crystalline compositions, and transfer film adhesion on coating behavior have been studied. The computational predictions, consistent with experimental observations, indicate specific interfacial regions between DLC and ductile metal inclusions are critical regions of stress and strain accumulation that can be precursors to material failure and wear. It is shown by varying the composition, resulting in tradeoffs between lubrication, toughness, and strength, the effects of these critical stresses and strains can be controlled for desired behavior. A mechanistic model to account for experimentally observed transfer film adhesion modes was also developed, and based on these results, it was shown that transfer film bonding has a significant impact on stress and wear behavior.

The exoskeleton of the lobster Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.

Despite the importance of litter on forest floor albedo and brightness, previous studies have not documented forest floor albedo or litter cover in any detail. Our objective was to describe the seasonal influence of litter on spectral albedos and nadir reflectances of a forest snowpack in a mixed-hardwood stand in the Sleepers River Research Watershed (SRRW) in Danville, Vermont (37°39′ N, 119°2′ W). Experimental measurements in a nearby open area at the Snow Research Station of the SRRW nearly duplicated the spectral trend observed in the forest. Spectral albedo and nadir reflectance measurements in the visible and near infrared (350–2500 nm) transitioned from a gently curved shape through the visible range (for finer-grained, lightly littered snow) to one having a peak in the red/near-infrared (near 760 nm) as the snowmelt season progressed (for coarser-grained, more heavily littered snow). The snowpack became optically thin as surface litter reached high percentages. A point-in-time digital photographic survey of the late-lying snowpacks of three forest stands and the open showed that median litter cover percentages in the coniferous, deciduous, mixed-forest, and an open area were 17·5, 6·1, 1·2, and 0·04 respectively. A Kruskal–Wallis ANOVA on ranks and pairwise comparisons using Dunn's test indicated that the litter covers of the three forest stands were significantly different with >95% confidence. The snowpack was relatively shallow (<1 m), as is typical for this area of Vermont. From a remote-sensing standpoint, and since shallow snow and increased grain size also lower the visible albedo, we can expect that snowpack litter will cause decreased albedo earlier in the snowmelt season, at deeper snow depths, and will tend to shift the maximum albedo peak to the red/NIR range as the melt season progresses. Published in 2001 by John Wiley & Sons, Ltd.

The work shows the effect of heat treatment T6 (solution and controlled precipitation of CuAl 2 ) on the microstructure of rheocast Al-4.5wt.% Cu alloy. Rheocast structures were obtained by partial melting to 40% liquid fraction from dendritic material with initial different grain sizes. Globular structures with grain sizes varying from 15 to 170 mm were produced and characterized for grain size, morphology, and Cu distribution and were mechanically tested, in both as-rheocast and T6 conditions. Results showed that increasing grain size results in a decrease in tensile and yield strengths, the latter according to a Hall -Petch type of relation. Elongation and constriction increase as grain diameter increases to a certain extent; for higher increase in grain diameter, these properties decrease. Concerning the effect of heat treatment in the structure, rheocast material requires more time for complete dissolution of the eutectic phase than cast structures, can keep higher Cu content in solution and prevents grain growth during holding. Greater improvement in mechanical properties is achieved by heat treatment in rheocast material.

A new idea of using a stiffer metallic compound Mg 2 Si to enhance the damping capacities of pure magnesium and its alloys is successfully attempted. The present paper focuses on the relation between damping capacities and the addition amount of Si. The results show that damping capacities increase with increasing amount of Si. Particular emphasis is placed on the increasing dislocation density around matrix-particulate interface and the refinement of grain size promoted by big growth restriction factor of Si.

Grain size analyses of three hilltop, primary eolian loess sequences in the Negev desert, southern Israel, show a bimodal grain-size distribution at 50-60 μm and 3-8 μm. Using analyses of mineralogy and OSL ages we demonstrate that the coarse mode is composed mostly of quartz grains and its relative magnitude increases regionally with time, suggesting an enhancement of a time-transgressive proximal dust source compared to a distal, Saharan fine-grain dust. The only proximal dust source for large amount of coarse silt quartz grains is the sands that advanced into Sinai and the Negev concurrently with the loess accretion during the late Pleistocene as a result of the exposure of the Mediterranean shelf. We therefore propose that the coarse silt quartz grains were formed through eolian abrasion within the margins of an advancing sand sea. This relationship between desert sand seas as a source for proximal coarse dust and desert margin loess deposits can be applicable to other worldwide deserts such as Northern Africa, China and Australia.

Solute transport rates within the uppermost 2 cm of a rippled continental shelf sand deposit, with a mean grain size of 400-500 mm and permeabilities of 2.0-2.4 Â 10 À11 m 2 , have been measured in situ by detecting the breakthrough of a pulse of iodide after its injection into the bottom water. These tracer experiments were conducted on the USA Middle Atlantic Bight shelf at a water depth of B13 m using a small tethered tripod that carried a close-up video camera, acoustic current meter, motorized 1.5 liter ''syringe'', and a microprofiling system for positioning and operating a solidstate voltammetric microelectrode. When triggered on shipboard, the syringe delivered a 0.21 M solution of potassium iodide and red dye through five nozzles positioned around and above the buried tip of the voltammetric sensor for 0.65-5 min. Bottom turbulence rapidly mixed and dispersed the tracer, which then was carried into the bed by interfacial water flows associated with ripple topography. The advective downward transport to the sensor tip was timed by a sequence of repetitive voltammetric scans. The distance-averaged vertical velocity, expressed as the depth of the sensor tip in the sand divided by the time to iodide breakthrough, was found to vary from 6 to 53 cm h À1 and generally to decrease with sediment depth. Because of episodic pumping and dispersion associated with the greatest 5% of wave heights and current speeds recorded, some concentration vs. time responses showed evidence of uneven solute migration. For reasons of mass balance, the advective flow field in the surface layers of permeable beds includes regions of water intrusion, horizontal pore-water flow and upwelling which also may explain some of the observed uneven migration. Pore-water advection was also evident in oxygen profiles measured before and after tracer injection with the voltammetric sensor. These profiles showed irregular distributions and oxygen penetration depths of 4-4.5 cm.

A fuzzy logic inference system was designed to predict the grain size of Inconel 718 alloy after upset forging. The system takes as input the original grain size, temperature, and reduction rate at forging and predicts the final grain size at room temperature. It is assumed that the ...

Measurement of seafloor microtopography is rapidly approaching the status as a standardized element of geoacoustic characterization of the sea floor. With the advent of underwater stereo cameras and, recently, multiple-megapixel digital cameras adapted for underwater use, more investigators are measuring seafloor roughness at high resolution for applications to high-frequency acoustic modeling. An assessment of the methodologies used to characterize seafloor roughness, the parameterizations of the characterization of seafloor roughness, and the predictability of seafloor roughness seems appropriate at this time. Use of the roughness power spectrum to characterize seafloor roughness has a wide applicability for acoustic modelers. Currently, the slope and intercept of the regression line through the roughness power spectrum are used to parameterize seafloor roughness for acoustic modeling. Recent availability of digital roughness height datasets allows computation of two-dimensional roughness power spectra at sub-cm resolution. Ideally, these 2-D spectra would make the estimation of 2-D roughness parameters from 1-D roughness parameters unnecessary. Although much seafloor microtopography has been characterized concomitantly with sediment grain size, empirical prediction of roughness from grain size remains problematic. The inherent problem in relating seafloor roughness parameters to grain size is that the sediment-water interface is dynamic. Although seafloor microtopography may be thought to evolve predictably through cycles driven by hydrodynamic and biological processes, the rates of these processes and the resultant bedforms are highly variable. Another aspect of seafloor roughness that needs to be addressed is the character of its power spectrum over several orders of magnitude of spatial dimensions.

In an attempt to explain an exceptionally strong magnetic anomaly near Stardalur, SW-Iceland, a 200 m deep hole was drilled into its centre and the core subjected to various mineralogical and geophysical measurements. In M~Sssbauer spectra of bulk samples from depths between 45 and 170 m the magnetic phase is predominant and consists of very pure magnetite. The area ratio for the components with hyperfine fields of 46 and 49 T is approximately 2. Comparison with spectra of selected basalt lavas showing similar magnetic properties indicates a distinctive difference. The strong remanent magnetism of the Stardalur samples can be explained by a combination of unusually high concentration in the rocks of pure magnetite, it's small grain size and a strong magnetic field appending its formation. It is suggested that both the composition of the magnetic phase and the strong magnetic field were brought about by hydrothermal alteration.

Embedded resistor circuits have been generated with the use of a Micropen system, Ag conductor paste (DuPont 6142D), a new experimental resistor ink from DuPont (E84005-140), and Low Temperature Co-fired Ceramic (LTCC) green tape (DuPont A951). Sample circuits were processed under varying peak temperature ranges (835°C–875°C) and peak soak times (10 min–720 min). Resistors were characterized by SEM, TEM, EDS, and high-temperature XRD. Results indicate that devitrification of resistor glass phase to Celcian, Hexacelcian, and a Zinc-silicate phase occurred in the firing ranges used (835–875°C) but kinetics of divitrification vary substantially over this temperature range. The resistor material appears structurally and chemically compatible with the LTCC. RuO2 grains do not significantly react with the devitrifying matrix material during processing. RuO2 grains coarsen significantly with extended time and temperature and the electrical properties appear to be strongly affected by the change in RuO2 grain size.

Preliminary investigations revealed that beryllides like Be 12 Ti may be much more suitable for neutron multipliers in future fusion power plants than pure beryllium. With suitable mechanical alloying and hot pressing methods, beryllium and beryllium-titanium tablets with grain sizes of 5 lm have been produced and analyzed by means of scanning electron microscopy (SEM), X-ray diffractometry, transmission electron microscopy (TEM) and plasma emission spectrometry. The fabricated tablets of Be-7.7 at.%Ti, corresponding to a chemical composition of the Be 12 Ti phase, have been arcmelted in an oxygen-free atmosphere. X-ray diffractometry, scanning and high resolution transmission electron microscopy measurements revealed that the vast majority of the ingots consist of nearly pure Be 12 Ti phase. Nineteen specimens have been fabricated from the ingots and shipped to HFR-Petten for the HIDOBE benchmark irradiation program that started in June 2005 with an aim to achieve 6000 appm He in Be and Be alloys at blanket relevant irradiation temperatures.

Exchange spring media are proposed for magnetic-recording systems consisting of a hard/soft bilayer. By varying the fraction of thickness for the hard and soft layer and by varying their saturation polarizations, the media properties can be optimized in order to achieve high thermal stability without increase of coercive field. In grains with identical size and coercivity, an optimized bilayer reaches an energy barrier exceeding those of optimized single-phase media by more than a factor of two. Thus, exchange spring media allow to reduce the grain diameter by more than a factor of 1 2. Additionally, the lower angular dependence of coercivity of exchange spring media improves the signal-to-noise ratio (SNR) by a factor of 2 5.

Detrital modes of modern Nile sands, together with estimates of sediment volumes trapped in Sudanese reservoirs, allow us to calculate sediment loads of major tributaries (Blue Nile, White Nile, Atbara) and erosion rates in the Nile catchment. A tridimensional array of high-resolution bulk-petrography and heavy-mineral data was obtained on both levee (suspended load) and bar (bedload) deposits, analysed separately for each grain-size subclass at 0.5Φ intervals. From available information on sediments stored in the Roseires, Khashm el Girba and Lake Nasser reservoirs between 1964 and 1990, the total Nile load is reassessed at 230 ± 20 10 6 t/a, an estimate two to four times higher than figures reported so far, on which previous estimates of sediment yields and erosion rates were based. Of such huge amount of detritus, 82 ± 10 10 6 t/a are contributed by River Atbara, which carries more volcanic rock fragments, brown augite and olivine from basaltic rocks, and 140 ± 20 10 6 t/a by the Blue Nile, which carries more K-feldspar and hornblende from amphibolite-facies basement rocks. The additional ≤10 7 t/a of almost purely quartzose sediments supplied by the rest of the Nile catchment, corresponding to insignificant average yields and erosion rates, represent the stable residue which survived extreme subequatorial weathering in southern Sudan swamps (White Nile, Bahr ez Zeraf, and Sobat sands) or fluvial and eolian recycling of ancient quartzarenites in hyperarid climates (Nubian sands). Sediment production is thus markedly focused on Ethiopian rift highlands, where rainfall is concentrated in a single July-August peak. High average yields and erosion rates (800 ± 150 t/km 2 a, 0.29 ± 0.05 mm/a) partly reflect anthropically-accelerated erosion caused by deforestation and intensive land use, and cannot be extrapolated far in the past. Erosion patterns may have changed repeatedly during Quaternary climatic oscillations, and possibly also in the longer term during the multistage rift-related events which, since impingement of the Afar plume and eruption of flood basalts in the Oligocene, caused elevated topography and monsoonal climate in Ethiopia.

The expansion in application of the selective laser melting (SLM) process for fabrication of new alloy materials continues. However, to date, there has been no investigation of the effect of this process on the final microstructure of 'melt sensitive' powder alloys such as mechanically alloyed oxide dispersion strengthened (ODS) FeCrAl. In this study commercial PM2000 powder, a ferritic ODS alloy strengthened by a fine dispersion of nano-scale yttria particles, was used in a layer based SLM rapid prototyping process to manufacture thin walls. Laser input power and scan speeds were varied between 10-50W and 0.1-0.3ms-1 , respectively. Electron channelling contrast images of the resulting microstructures revealed a columnar grain structure aligned perpendicular to the surface of the build substrate. Measurements of the diameter of yttria particles retained in the walls using transmission electron microscopy indicated that agglomeration and coarsening had taken place for samples processed at the slowest scan speed. By contrast ODS particles retained in a wall made at twice the slowest scan speed showed no evidence of agglomeration and appeared to have coarsened to a lesser extent, exhibiting a smaller mean diameter. This opens the possibility of using these alloys in novel applications processed using rapid prototyping technologies.

The mesoscale (time) control of annual storm-surge activity on quasi-annual saltmarsh (tidal marsh) deposition is studied from two estuarine saltmarshes on the high-energy NW coast of Ireland. Both saltmarshes exhibit a cliffed edge where maximum sedimentary variation is expressed in the form of lamination. Sections were logged and characterised by lithofacies based on grain-size determinations. Sections dated using Cs and

Polycrystalline ferrites with general formula Ni 1−x Zn x Fe 2 O 4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) were prepared by oxalate precipitation method. The samples were characterized by X-ray diffraction (XRD), IR and scanning electron microscope (SEM) techniques. All compositions show cubic Spinel structure. Lattice constant increases with increase in zinc content, obeying Vegard's law. The physical densities are about 98.14% of their X-ray density. Average crystallite size lies in the range 27.59-31.49 nm. Infrared studies show two absorption bands near about 400 cm −1 and 600 cm −1 for octahedral and tetrahedral sites, respectively. The resistivity of all the samples was studied. It is observed that the resistivity of nickel-zinc ferrites prepared by oxalate precipitation method is higher than that prepared by ceramic and citrate precursor method. It is attributed to greater homogeneity and smaller grain size. Activation energy in paramagnetic region is higher than that of ferrimagnetic region.

Titanium has been incorporated in CuInS 2 thin films and devices by diffusion of Ti from the substrate during the CuInS 2 co-evaporation growth process. The CuInS 2 crystal structure is unaffected but the grain size is reduced compared to Ti-free reference samples. X-ray photoelectron spectroscopy shows the presence of TiO 2 at the front of the absorber layer, which appears at the heterojunction interface of the completed CuInS 2 /TiO 2 /CdS/ZnO solar cells. Low temperature photoluminescence spectra show no additional transitions that could be assigned to Ti-based impurity defect levels. Ti-containing cells show conversion efficiencies higher than the Ti-free reference cells due to higher open-circuit voltage (efficiency 11%, V OC ¼ 731 mV). No reduction in short circuit current is detected, indicating that the titanium does not introduce additional bulk recombination. Temperature-dependent current-voltage measurements indicate a reduced interface recombination for cells containing Ti, which is attributed to the TiO 2 interlayer detected by X-ray photoelectron spectroscopy.

Single crystal plasticity based on a representative characteristic length is proposed and introduced into a homogenization approach based on finite element analyses, which are applied to characterization of distinctive yielding behaviors of polycrystalline metals, yield-point elongation, and grain size strengthening. The computational manner for an implicit stress update is derived with the framework of a standard multi-surface plasticity at finite strain, where the evolution of the characteristic lengths are numerically converted from the accumulated slips of all of slip systems by exploiting the mathematical feature of the characteristic length as the intermediate function of the plastic internal variables. Furthermore, a constitutive model for a single crystal reproduces the stress-strain curve divided into three parts. Using two-scale finite element analysis, the macroscopic stressstrain response with yield-point elongation under a situation of low dislocation density is reproduced. Finally, the grain size effect on the yield strength is analyzed with modeling of the grain boundary in the context of the proposed constitutive model and is discussed from both macroscopic and microscopic views.

New evidence is provided for the aeolian origin of the upper unit of the Boa Vista Formation, found in the eastern part of the Brazilian state of Roraima and in neighboring Guyana. This unit has two geomorphologicallyrsedimentologically distinct domains: a sandy and a silty realm.

The use of magnetic measurements in the detection of fire signals has been neglected since the work of , yet considerable developments have been made in the interpretation of magnetic measurements over the last 16 years. This paper presents a study of the fire history of Lago di Origlio in the southern Swiss Alps. The study utilises the technique of mineral magnetism alongside the stratigraphic pollen, spore and charcoal records. Correlation between the various proxy records indicates that a magnetic 'fire' record is present within the sediments for the last 4 ka. The magnetic fire record has a distinct mineralogical and magnetic grain size signature that can be recognised against the background sedimentary signal. The results suggest that magnetic measurements may be usefully employed in the reconstruction of fire history. Their application is rapid and non-destructive and the results may provide additional information in relation to the links between catchment fire events and the sedimentary record.

Grain growth in systems of anisotropic grain boundary energy and mobility is investigated by computer simulations in a two-dimensional textured polycrystalline system. The energy and mobility are allowed to depend on both grain boundary inclination and misorientation. Mobility anisotropy alone does not significantly change the growth kinetics or statistical distributions of misorientation, grain size and number of grain edges, even though grain shapes evolve in a self-dissimilar fashion where the aspect ratio of grains and inclination distribution of grain boundaries are time dependent. Energy anisotropy, however, causes significant deviation of grain growth kinetics, misorientation and edgedistributions from the ones observed in isotropic systems. Moreover, misorientation distribution is skewed towards low energy (special) boundaries. Size distributions are similar in all cases. Mobility anisotropy influences grain growth kinetics only when energy is also anisotropic. Variation of misorientation distribution with time plays the key role in determining the grain growth behavior. 

... J. Germán Rodríguez and Adolfo Uriarte ... View larger version (15K), Table 1. Pearson product moment correlations between cumulative percentiles, measured by laser diffractometry and by dry sieving on sandy marine sediments (n = 68). View larger version (27K), ...

The global move toward reducing the usage of lead in electronics manufacturing industry is driving the industry to switch from tin-lead alloys to pure tin (Sn) for its component plating process. This transition has resulted in a reliability concern due to the formation of conductive Sn whiskers, which can grow from the component after the plating process within a few hours to months, with their length ranging from 10 micrometers up to several millimeters. The conductive Sn whiskers may cause current leakage or short circuits, leading to catastrophic failure in the field. This paper presents the results of an experimental study on Sn whisker formation based on the effects of annealing for 1 h at 150°C and environmental test conditions from the joint electron devices engineering council standards. This paper consisted of one temperature cycling test and two isothermal storage tests. The characterization results obtained confirm that temperature cycling and isothermal storage favor the formation of whiskers on Sn-plated copper lead frames. The average maximum length of the whiskers increased with the number of temperature cycles and duration of isothermal storage. It is also shown that annealing for 1 h at 150°C of the samples is effective in reducing the average maximum length of whiskers. Growth mechanisms of the Sn whiskers due to the effects of annealing and without annealing are also discussed.

Recent chirp seismic reflection data combined with multibeam bathymetry, backscatter, and analysis of grab samples and short cores provide evidence of significant recent erosion on the outer New Jersey shelf. The timing of erosion is constrained by two factors: (1) truncation at the seafloor of what is interpreted to be the transgressive ravinement surface at the base of the surficial sand sheet, and (2) truncation of apparently moribund sand ridges along erosional swales oriented parallel to the primary direction of modern bottom flow and oblique to the strike of the sand ridges. These observations place the erosion in a marine setting, post-dating the passage of the shoreface ravinement and the evolution of sand ridges that form initially in the near shore environment. Also truncated by marine erosion are shallowly buried, fluvial channel systems, formed during the Last Glacial Maximum and filled during the transgression, and a regional reflector bRQ that is N~40 kyr. Depths of erosion range from a few meters to N 10 m. The seafloor within eroded areas is often marked by bribbonQ morphology, seen primarily in the backscatter data as areas of alternating high and low backscatter elongated in the direction of primary bottom flow. Ribbons are more occasionally observed in the bathymetry; where observed, crests exhibit low backscatter and troughs exhibit high backscatter. Sampling reveals that the high backscatter areas of the ribbons consist of a trimodal admixture of mud, sand and shell hash, with a bimodal distribution of abraded and unabraded sand grains and microfauna. The shell hash is interpreted to be an erosional lag, while the muds and unabraded grains are, in this non-depositional environment, evidence of recent erosion at the seafloor of previously undisturbed strata. The lower-backscatter areas of the ribbon morphology were found to be a wellsorted medium sand unit only a few 10's of cm thick overlying the shelly/muddy/sandy material. Concentrations of wellrounded gravels and cobbles were also found in eroded areas with very high backscatter, and at least one of these appears to be derived from the base of an eroded fluvial channel. Seafloor reworking over the transgressive evolution of the shelf appears to have switched from sand ridge evolution, which is documented to~40 m water depth, to more strictly erosional modification at greater water depths. We suggest that this change may be related to the reduction with water depth in the effectiveness of sediment resuspension by waves. Resuspension is a critical factor in the grain size sorting during transport by bottom currents 0025-3227/$ -see front matter D (J.A. Goff).

Strain induced grain refinement of an Al-1 wt.%Mg alloy processed by equal channel angular pressing (ECAP) at cryogenic temperature is investigated quantitatively. The results show that both mean grain and subgrain sizes are reduced gradually with increasing ECAP pass. ECAP at cryogenic temperature increases the rate of grain refinement by promoting the fraction of high angle grain boundaries (HAGBs) and misorientation at each pass. The fraction of HAGBs and the misorientation of Al-1 wt.% Mg alloy during ECAP at cryogenic temperature increase continuously as a function of equivalent strain. Both {110} and {111} twins at ultrafine-grained size are observed firstly in Al-Mg alloy during ECAP. The analysis of grain boundaries and misorientation gradients demonstrates the grain refinement mechanism of continuous dynamic recrystallization.

In this report we show that the amplitude of specularly diffracted light from a plane rough surface as a function of incident angle cosine is Fourier transform of the height distribution on the surface. Therefore, an even height distribution function, which is the case for many rough surfaces, can be obtained by measuring the specularly diffracted light intensities. Also, it is observed that for polychromatic illumination the spectrum of the specularly diffracted light is modified and the modification depends on roughness, incident angle, and wavelength. It is also shown that, for a fixed incident angle, the height distribution on the rough plane is Fourier transform of the spectral modifying function. Experimental studies on some surfaces of different roughnesses, prepared by grinding sheet-glasses by powders of different grain sizes, show that the corresponding height distributions are Gaussian and the rms heights obtained by the two approaches are quite consistent.

Experiments were performed to observe the deformation characteristics of oxygen-free high-conductivity (OFHC) copper at high strain rates (up to 40,000 s-1) and to relate differences in grain size with differences in deformation behavior. The rod impact and torsional Hopkinson bar test methods were used in these experiments. Results show that grain size reductions substantially reduce surface irregularities that develop during deformation. The effect of grain size on the yield stress and on the strain-hardening behavior of copper is small and is similar to the effect of grain size in copper at quasistatic strain rates. The observation that grain size has a substantial effect on surface irregularities may have important implications for applications in which stable deformation of thin sections is of concern.

Distribution and character of sedimentary facies in a 196.5-m core from Ocean Drilling Program (ODP) Site 893 in Santa Barbara Basin (southern California) reflect global and regional controls during the latest Quaternary. Stratigraphic trends in grain size, sediment composition, sedimentary fabric, and degree of bioturbation record changes in oceanic deep-water circulation, climate, sea level, basin geometry, sediment sources, and transport pathways through the last two glacial and interglacial episodes (-160 k.y.). The sedimentary sequence in Hole 893A is divided into six facies: four record varied levels of bottomwater oxygenation by the degree of bioturbation of primarily laminated olive-gray hemipelagic mud, whereas two reflect coarse-and fine-grained event deposition. Varved sediments typical of the Holocene Santa Barbara Basin compose only 21% of the entire latest Quaternary sequence. An ultra-high-resolution record (<lO-yr sample spacing) of bottom-water oxygenation, as shown by the preservation or destruction of annual varves, reveals cyclic variation over decadal to Milankovitch time scales and apparently reflects the changing age and ventilation of Pacific Intermediate Waters. Over the past-75 k.y., bioturbation and basin oxygenation correspond closely to glacial-interglacial oscillation, with warm intervals being oxygen-depleted and laminated and cold intervals being oxygenated and bioturbated. Preliminary results suggest a correlation between basin stratigraphy and deep-water circulation proxy records from elsewhere in the Pacific and Atlantic oceans, indicating that sediments of Santa Barbara Basin are a sensitive recorder of global and regional paleoceanographic and paleoclimatic change.

Oxidation rates of low sulphide (<0.5 wt.%) gneissic waste rock from the Clu lake U mine, northern Saskatchewan, Canada were determined using 3 independent methods: O 2 consumption rates in kinetic cells, SO 4 measurements of kinetic cell euent and humidity cell SO 4 release rates. The O 2 consumption measurements demonstrated that the oxidation of pyrite was strongly dependent on grain size and moderately dependent on water content, temperature and microbiology. Oxygen consumption rates were highest at water contents of 5±10 wt.% (12±25% saturation). Measured SO 4 release rates (3.1±91 mg SO 4 kg À1 wk À1 ) for the kinetic cells were comparable to rates calculated from the O 2 consumption values (6.9±70 mg SO 4 kg À1 wk À1 ). Sulphate release rates determined from humidity cells were generally higher than those obtained from the kinetic cells, ranging from 6 to 64 mg SO 4 kg À1 wk À1 for the coarsest and ®nest fraction, respectively. These dierences were attributed to sample heterogeneity. #

Fracture toughness of Al 2 O 3 platelet-reinforced hydroxyapatite (HAP) ceramics was investigated using the Vickers' indentation technique. The geometrical anisotropy of alumina platelets induces an anisotropic toughening. The ef®ciency of reinforcing mechanisms remains maximum for a crack propagating with an angular deviation inferior to 30 around the direction perpendicular to alumina disc faces. This is assumed to result from a crack de¯ection mechanism which induces a favorable contribution of mode II failure. A small effect of hydroxyapatite grain size becomes noticeable in the direction parallel to alumina disc faces. The toughening depends on the size and volume content of alumina platelets. Large size platelets provoke a spontaneous microcracking of the HAP matrix which is detrimental to the mechanical reliability, whereas small platelets lead to a strong toughening. The results relate to the intensity of thermoelastic residual stresses within the matrix around alumina inclusions.