Shallow Edge Research Articles

Effect of arbitrary bi‐material combination and bending loading conditions on stress intensity factors of an edge interface crack

PurposeThe purpose of this paper is to compute the stress intensity factors (SIFs) of single edge interface crack for arbitrary material combinations and various relative crack lengths, and compare with those for the bonded plates subjected to tensile loading conditions. It aims to discuss the results of the shallow edge interface crack on the basis of the singular stress near the free‐edge corner without the crack.Design/methodology/approachIn this study, the SIFs of interface crack in dissimilar bonded plates subjected to bending loading conditions are analyzed by the finite element method and a post‐processing technique. The use of post‐processing technique of extrapolation reduces the computational cost and improves the accuracy of the obtained result.FindingsThe empirical expressions are proposed for evaluating the SIFs of arbitrary material combinations.Originality/valueEmpirical functions can be used to obtain the SIFs for arbitrary material combinations for the bending loading conditions easily. It is very convenient for engineering application.

Incorporating spatial variation of nitrification and denitrification rates into whole‐lake nitrogen dynamics

Despite dramatic increases in nitrogen (N) loading to fresh waters and growing scientific attention on the changing N cycle, measurements of nitrification and denitrification rates in lakes are lacking. In particular, we know little about how these processes vary spatially within a lake, and how this potential spatial variation contributes to a lake's N dynamics. We measured sediment nitrification and denitrification rates at 40 sites in Gull Lake, Michigan (USA), and found that the shallow edge sediments (<2 m deep) of the lake were hot spots of N transformation. Nitrification rates were comparable in sediments at all depths, while sediment denitrification rates were highest in the shallow edge habitat, and lowest in the profundal sediments (<2 m and >10 m deep, respectively). We scaled‐up our sediment transformation rates across the lake to illustrate spatial variability in nitrification and denitrification. For whole‐lake nitrification, the contribution of shallow edge, littoral, and profundal sediments followed in proportion to lake surface area of each habitat. In contrast, the contribution of each of these areas to whole‐lake denitrification was not proportional to their respective surface areas, and instead was equal across the 3 habitat types, with each area contributing roughly 30% of the total N loss via denitrification. Spatially representative characterization of nitrification and denitrification in lentic ecosystems requires incorporation of the spatial variation in these transformations with a particular focus on littoral sediments, and this is often overlooked in studies of lentic N cycling. Furthermore, anthropogenic changes to lake shorelines that influence N cycling in littoral sediments may have a disproportionate effect on whole‐lake ecosystem function.

Analysis of the specific features of propagation of tsunamis in the shelf zone of the basin

A 3D model of nonlinear long waves is applied to the numerical analysis of the propagation of tsunami waves from a rectangular zone of generation in a basin with continental slope and shelf zone. The waves are generated by unidirectional displacements of a bounded area of the bottom of the basin for a finite period of time. It is shown that the efficiency of wave generation depends on the location, horizontal sizes, and duration of deformations of the bottom. The run-up of waves onto the vertical coastal boundary is maximum for short-term shifts of the bottom, for large zones of generation, and seismic sources located on the continental slope. The reflection of waves from the coast leads to the formation of two waves entrapped by the shelf and propagating along the coast in the opposite directions from the zone of the initial wave impact. A partial entrapping of waves by the shelf is observed. This phenomenon manifests itself in the form of multiple reflections of the waves from the coast and the shallow edge of the continental slope and is absent in the case of generation of waves in the deep-water part of the basin.

Feeding preferences of herbivores in a relatively pristine subtropical seagrass ecosystem

Understanding forage choice of herbivores is important for predicting the potential impacts of changes in their abundance. Such studies, however, are rare in ecosystems with intact populations of both megagrazers (sirenians, sea turtles) and fish grazers. We used feeding assays and nutrient analyses of seagrasses to determine whether forage choice of grazers in Shark Bay, Australia, are influenced by the quality of seagrasses. We found significant interspecific variation in removal rates of seagrasses across three habitats (shallow seagrass bank interior, shallow seagrass bank edge, deep), but we did not detect variation in gazing intensity among habitats. In general, grazers were more likely to consume fast-growing species with lower carbon : nitrogen (C : N) and carbon : phosphorus (C : P) ratios, than the slower-growing species that are dominant in the bay. Grazer choices were not, however, correlated with nutrient content within the tropical seagrasses. Slow-growing temperate seagrasses that experienced lower herbivory provide greater habitat value as a refuge for fishes and may facilitate fish grazing on tropical species. Further studies are needed, however, to more fully resolve the factors influencing grazer foraging preferences and the possibility that grazers mediate indirect interactions among seagrass species.

Effect of sputtering power on the properties of Cd 1 − x Zn xTe films deposited by radio frequency magnetron sputtering

Cd 1 − x Zn xTe films were prepared by radio frequency (r.f.) magnetron sputtering from Cd 0.9Zn 0.1Te slices target with different sputtering power (60–120 W). The effects of sputtering power on the properties of Cd 1 − x Zn xTe films were studied using X-ray diffraction (XRD), energy dispersive X-ray (EDX), atomic force microscopy (AFM), ultraviolet spectrophotometer and Hall effect measurements. The composition of the deposited films was determined by EDX. The Cd content was found always to be higher than the Te content, regardless of sputtering power. This behavior may be explained by the preferential sputtering of cadmium atoms in the target. XRD studies suggest that ZnTe secondary phases were coexisted in Cd 1 − x Zn xTe films. The origin of the secondary phase is ascribed to the lowest sticking coefficient of Zn atom. AFM micrographs show that the grain size increases with the sputtering power. The optical transmission data indicate that shallow absorption edge occurs in the range of 750–850 nm, and the sputtering power does not have a clear effect on the optical absorption coefficient. In Hall Effect measurements, the sheet resistivities of the deposited films are 1.988 × 10 8, 8.134 × 10 7, 8.088 × 10 7 and 3.069 × 10 7 Ω/sq, respectively, which increase with the increasing of sputtering power.

Measuring Lifting Forces in Rock Climbing: Effect of Hold Size and Fingertip Structure

This study investigates the hypothesis that shallow edge lifting force in high-level rock climbers is more strongly related to fingertip soft tissue anatomy than to absolute strength or strength to body mass ratio. Fifteen experienced climbers performed repeated maximal single hand lifting exercises on rectangular sandstone edges of depth 2.8, 4.3, 5.8, 7.3, and 12.5 mm while standing on a force measurement platform. Fingertip soft tissue dimensions were assessed by ultrasound imaging. Shallow edge (2.8 and 4.3 mm) lifting force, in newtons or body mass normalized, was uncorrelated with deep edge (12.5 mm) lifting force (r < .1). There was a positive correlation (r = .65, p < .05) between lifting force in newtons at 2.8 mm edge depth and tip of bone to tip of finger pulp measurement (r < .37 at other edge depths). The results confirm the common perception that maximum lifting force on a deep edge ("strength") does not predict maximum force production on very shallow edges. It is suggested that increased fingertip pulp dimension or plasticity may enable increased deformation of the fingertip, increasing the skin to rock contact area on very shallow edges, and thus increase the limit of force production. The study also confirmed previous assumptions of left/right force symmetry in climbers.

Effects of deposition temperatures on structure and physical properties of Cd 1−xZn xTe films prepared by RF magnetron sputtering

Cd 1− x Zn x Te films were deposited by RF magnetron sputtering from Cd 0.9Zn 0.1Te crystals target at different substrate temperatures (100–400 °C). The effects of the deposition temperature on structure and physical properties of Cd 1− x Zn x Te films have been studied using X-ray diffraction (XRD), step profilometer, atomic force microscopy (AFM), ultraviolet spectrophotometer and Hall effect measurements. X-ray studies suggest that the deposited films were polycrystalline with preferential (1 1 1) orientation. AFM micrographs show that the grain size was changed from 50 to 250 nm with the increase of deposition temperatures, the increased grain size may result from kinetic factors during sputtering growth. The optical transmission data indicate that shallow absorption edge occurs in the range of 744–835 nm and that the optical absorption coefficient is varied with the increase of deposition temperatures. In Hall Effect measurements, the sheet resistivities of the deposited films are 3.2×10 8, 3.0×10 8, 1.9×10 8 and 1.1×10 8 Ohm/sq, which were decreased with the increase of substrate temperatures. Analysis of the resistivity of films depended on the substrate temperatures is discussed.

Simulations of Strong Ground Motion and 3D Amplification Effect in the Taipei Basin by Using a Composite Grid Finite-Difference Method

We perform full elastic wave-field simulations within the Taipei basin by using a three-dimensional (3D) discontinuous finite-difference method. The 3D Taipei basin model is determined from a seismic reflection study. Two major subsurfaces, the Songshan formation (surface soil layer) and the basin basement, are constituted in the model. A parallel-based composite grid technique, a containing scalene grid and a discontinuous grid, is developed in this study to deal with the possible numerical prob- lem of thin depth and low velocity of the Songshan formation. Taking advantage of the composite grid, the resolution of the subsurface structure can be reached to 20 m, and a higher frequency (up to 3 Hz) of the synthetic waveform can be achieved. In our strong ground motion simulations, we assume a constant velocity in each subsurface. Three different types of models are considered in the study: the Songshan formation with a basement structure model, a basin basement model, and a layered half-space model. Results indicate that only the model with both the Songshan formation and the basement structure can produce the apparent basin amplification effects. First, the surface wave generated after the primary S wave is trapped at the shallow part of the basin. Then, when the wave propagates through the deepest part of the basin, most of the energy is reflected from the boundary and focused back into the basin. In addi- tion, part of the seismic wavefront turns and follows the shallow basin edge resulting in further amplification. Our study indicates that the complex Taipei basin geometry and fairly low velocity of the Songshan formation dominate the amplification and wave propagation behavior that result in extraordinary strong shaking patterns in the Taipei metropolitan region.

Stressed state of a half plane with shallow edge crack under Hertzian loading (a survey)

We present a survey of works dealing with the stress intensity factors (SIF) for shallow edge cracks formed in elastic half planes subjected to the action of Hertzian loads moving along the boundaries of the planes. The numerical data on the SIF obtained by the method of singular integral equations are compared with the results of the other authors. The best agreement is observed with the results obtained by Keer and Bower by using the dislocation approach. The agreement with the results obtained by the finite-element method is satisfactory.

The Pond

155 The Pond Jonatha Ceely After the husband retired from the investment firm in the city and the wife from the suburban medical practice where she was the claims manager, the couple established a new habit of walking for an hour every morning. Life would be healthier for them now, they agreed. He no longer rushed to board the train that trundled commuters through grimy yards, past storage sheds, along weed-grown rights of way. She no longer hurried, tense behind the wheel, to claim a convenient parking place near the sprawling, red brick buildings of the medical center. Leisure was theirs now and time to enjoy the world of nature; they had earned it. Almost every day, after a quiet breakfast, they walked to the conservation area just down the road from their suburban house. They crossed the small parking area and followed a trail that looped through the woods, around a pond, up over a low rise between meadows, and back again to the road and the beginning. They congratulated themselves that now, after years of work, of fitting home repairs and trimming the forsythia and mowing the lawn around the demands of their jobs, their choice of a semi-rural location was paying off. They would enjoy the changing seasons, the wayside flowers, the wild life, at last. Over the years they had contributed money to the town’s conservation effort. Walking, listening to the birds, chatting, bidding the occasional passerby good morning, they reaped the reward for their generosity. The well-maintained paths, the dredged pond that reflected the sky, the mowed meadow were all theirs to enjoy now. Beside the pond the town had placed a granite bench. During the first three years of their retirement, the couple walked briskly past the bench, savoring the odors of wet grass and mud from the margin of the pond in March or noting the thickening ice in December. The water sparkled blue in the sunshine, the reeds grew green and ripened into brown cattails, a red-winged blackbird flashed its colors to them. 156 Ecotone: reimagining place In the fourth spring of their retirement, they still walked; they were determined to keep life normal, but now they stepped aside to let more vigorous walkers pass them and paused at the bench by the pond so the wife could rest. Although she tired quickly, she was making a good comeback, they assured each other. The scars from the surgery were healing. By the end of April she had gained a little weight. They did not remind each other as they sat side by side on the granite slab of the bench, their jackets shielding their thin haunches from the chilly stone, that in two weeks, when she was a little stronger, she would return to the city hospital for chemotherapy treatments. All May and into June they walked, no matter what the weather. The treatments were not as debilitating as they had feared. Exercise would help her recovery; there were studies to prove it. She was determined to go out. Certainly, they believed, years of life in the suburbs, almost the country really, and their comfortable circumstances equipped them well to face nature. Their mudroom was well stocked with boots and coats and hats for all seasons. On a June morning, husband and wife, clad in light rain gear, sat on the bench as a fine drizzle puckered the surface of the pond. Young vegetation gleamed chartreuse and darker green, sunlight slanted pale gold through mist among the trees on the other side of the water. The couple sat silent. A bird somewhere to the right spilled an abrupt cadence of notes and then stopped as suddenly as it began. The reeds growing from the muck along the edge of the pond rustled. “Oh look,” the wife breathed. A female mallard trailed by six ducklings paddled along the shallow edge of the pond. Puffs of yellow, they drifted on the water like pollen. They rode their mother’s wake, gobbling at the fragments of green scum her passage scattered. “How adorable,” she said, and when the couple rose from the bench and walked on, she seemed to have...

Why Corals Recruit Successfully in Top-Shell Snail Aquaculture Structures?

In 1996 and 1997, concrete box structures were installed in a shallow reef edge at Miyako Island, Okinawa (24°55'45"N 125°15'55"E) for rearing the commercially important top shell snail Trochus niloticus. Corals quickly attached on the quartz sandcoated fiberglass reinforced plastic latticed substrata on the bottom of the box. Within few years after severe damage of corals following extensive bleaching in 1998, however, the lattice was covered by Acropora-dominated coral colonies. In November 2005, coral coverage in four boxes was 50 to 90%. There were 25 species and the average size of the coral colonies was around 50 cm.The accidental and rapid recruitment of corals on these aquaculture structures seems to have created an ideal environment for coral recruitment and growth. This finding provides a unique opportunity to gain insight into critical mechanisms of coral recruitment that may be used to improve coral reef restoration. The present paper deals with the aquaculture structures, environment, species diversity of corals, and possible factors that may have contributed to coral recruitment and growth.

Temperature-Dependence of Off-State Drain Leakage in X-Ray Irradiated 130 nm CMOS Devices

The off-state drain current leakage characteristics of 130 nm CMOS technology are investigated using x-ray irradiation and operating temperature as variables. Radiation-induced interface traps in the gate oxide to gate-drain overlap region strongly enhance the off-state leakage as a function of gate bias. Due to the thin gate oxide in these 130 nm devices, we find that drain-edge direct tunneling is more plausible than conventional gate-induced-drain-leakage in explaining the observed increase in drain leakage. Radiation-induced traps in the shallow trench isolation oxide create parasitic channels in the p-well and produce another source of off-state drain leakage with increasing total dose. The drain current increase from both the gate overlap region and the shallow trench edge are enhanced with increasing total dose and suppressed by cooling

On the geometrical dependence of low-frequency noise in SiGe HBTs

We present an investigation of the dependence of low-frequency noise on device geometry in advanced npn silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs). The devices examined in this work have fixed emitter width (WE=0.4μm), but varying emitter length (0.5μm⩽LE⩽20.0μm), and thus the ratio of the emitter perimeter (PE) to the emitter area (AE) varies widely, making it ideal for examining geometrical effects. The SPICE noise parameter AF extracted from these devices decreases with increasing LE. Furthermore, the low-frequency noise measured on SiGe HBTs with significantly different PE/AE ratios suggests a possibility that the fundamental noise source for the diffusion base current may be located at the emitter periphery. Transistors with different distances between the emitter edge and the shallow trench edge (XEC), and shallow trench edge to deep trench edge (XTC), are also investigated. The SiGe HBTs with a smaller value of XEC have higher low-frequency noise, but no significant difference is found in devices with varying XTC. Explanations of the observed noise behavior are suggested.

A semi-infinite chamfered contact solution and its application to almost complete contacts

The solution for a semi-infinite rigid block having a flat face but with a small, shallow edge chamfer, and pressed onto an incompressible half-plane, is considered. The surface traction distribution and internal state of stress under both normal and a monotonically increasing shearing force are found, and the characteristics of the solution explored. As an example it is employed to find the edge-solution for a finite square-ended but chamfered punch in contact with a half-plane.

Validation of a randomization procedure to assess animal habitat preferences: microhabitat use of tiger sharks in a seagrass ecosystem

1. Tiger sharks Galeocerdo cuvier are important predators in a variety of nearshore communities, including the seagrass ecosystem of Shark Bay, Western Australia. Because tiger sharks are known to influence spatial distributions of multiple prey species, it is important to understand how they use habitats at a variety of spatial scales. We used a combination of catch rates and acoustic tracking to determine tiger shark microhabitat use in Shark Bay. 2. Comparing habitat-use data from tracking against the null hypothesis of no habitat preference is hindered in Shark Bay, as elsewhere, by the difficulty of defining expected habitat use given random movement. We used randomization procedures to generate expected habitat use in the absence of habitat preference and expected habitat use differences among groups (e.g. males and females). We tested the performance of these protocols using simulated data sets with known habitat preferences. 3. The technique correctly classified sets of simulated tracks as displaying a preference or not and was a conservative test for differences in habitat preferences between subgroups of tracks (e.g. males vs. females). 4. Sharks preferred shallow habitats over deep ones, and preferred shallow edge microhabitats over shallow interior ones. The use of shallow edges likely increases encounter rates with potential prey and may have profound consequences for the dynamics of Shark Bay's seagrass ecosystem through indirect effects transmitted by grazers that are common prey of tiger sharks. 5. Females showed a greater tendency to use shallow edge microhabitats than did males; this pattern was not detected by traditional analysis techniques. 6. The randomization procedures presented here are applicable to many field studies that use tracking by allowing researchers both to determine overall habitat preferences and to identify differences in habitat use between groups within their sample.

High resolution 3-D velocity structure in the source region of the 2000 Western Tottori Earthquake in southwestern Honshu, Japan using very dense aftershock observations

Abstract We carried out high density aftershock observations a week after the 2000 Western Tottori Earthquake for 40 days. We deployed 72 seismic stations in and around the aftershock area. The average spacing of the stations in the aftershock area was 4–5 km. We determined accurate hypocenters and focal mechanisms for ∼1,000 aftershocks and obtained a high resolution 3-D velocity structure in the source region. High P and S wave velocity anomalies (&gt; 4%) near the southeasternmost aftershock area at 2 km depth correlated with Jurassic to Late Cretaceous plutonic and high pressure metamorphic rocks. The depth distribution of the P and S wave velocities along the mainshock fault showed that high velocity anomalies were located at the shallow southeastern edge and the deeper central part of the aftershock area. The ratio between P and S wave velocities in the high velocity anomalies was a little higher (∼1.75) than the average value (∼1.70) in the upper crust. These results indicate that the high velocity anomalies could correspond to the plutonic or metamorphic rocks. The distributions of the high velocity anomalies and large slips of the mainshock were complementary. These suggest that the high velocity anomalies could be stronger than the surrounding materials and might behave as barriers to the mainshock rupture.

A Shallow and Deep Trench Isolation Process Module for RF BiCMOS

A shallow and deep trench isolation process module for high performance rf bipolar complementary metal-oxide-semiconductor (BiCMOS) is presented in detail. The shallow trench is etched prior to the deep trench, allowing the deep trench to be placed self-aligned to the shallow trench edge. By planarizing the polycrystalline silicon deep trench filling using chemical mechanical polishing (CMP) before etchback, the recess into deep trenches is decreased and polysilicon spacer formation at the active area edges is avoided. The poly CMP is stopped before all polysilicon in the active area is removed, to avoid polysilicon dishing and erosion of oxide on top of nitride on active area. Important issues arising during process development are discussed. Two different slurries were evaluated, which resulted in two different nonuniformities of polysilicon thickness. Nonuniformity transfers partially down to a range of recesses into the deep trenches, but the recesses were much smaller compared to the etchback only. High-density chemical vapor deposition was used for shallow trench filling and a direct shallow trench isolation-CMP process was developed. The feasibility of the process module was demonstrated using a 0.25 μm, 200 mm bipolar double-poly rf process with optional SiGe epi base. Electrical results from completed transistors are presented to verify the function of the module. © 2004 The Electrochemical Society. All rights reserved.

Ultimate and service behavior of ferrocement roof slab panels

The aim of this research paper is to study the ultimate and service behavior of ferrocement roof slab panels. The test results of six simply supported roof slab panels are presented. The parameters of study include: the effect of the percentage of wire mesh reinforcement by volume and the structural shape of the panels on the ultimate flexural strength, first crack load, crack spacing and load-deformation behavior. The results indicate that the use of monolithic shallow edge ferrocement beams with the panels considerably improves the service and ultimate behavior of the panels, irrespective of the number of steel layers used.

Structure of deep-sea pelagic fish assemblages in relation to the Mid-Atlantic Ridge (45°–50°N)

Pelagic fishes from depths of 250 to 3200 m from 45°N to 50°N were sampled during a mid-Atlantic cruise in 1982. These clustered into 6 assemblages, which were related to the Mid-Atlantic Ridge, the continental shelf edge and oceanic habitats. Spatial distribution of clusters coincided with SST and surface chlorophyll patterns. Cluster distribution further coincided with published mid-depth hydrography indicating that hydrographic recirculation features were an important determinant of community structure. Over the ridge, Melamphaidae, Serrivomeridae, Stomiidae and Centrolophidae increased in abundance. Horizontally, the myctophid Benthosema glaciale indicated the transition from temperate-subtropical to temperate-subarctic waters. The gadid Micromesistius poutassou and the alepocephalid Xenodermichthys copei were characteristic species for the shallow shelf edge assemblage. Vertically, extended depth ranges were stated for assemblages above MAR and the southern leg, as indicated for the species Gonostoma bathyphilum, and Schedophilus medusophagus. This was further tested for the saccopharyngid Saccopharynx ampullaceus. The increase of gelatinous plankton feeders over the ridge, in particular for S. medusophagus, is discussed with respect to a probable increase of gelatinous plankton abundance in the area considered. An error model was developed to address the contamination problem with respect to non-closing devices.

Impact of the interaction between nitrogen implant and NO anneal on narrow-width transistors

This study reports a new behavior in narrow-width transistors resulting from the interaction of oxides grown with nitrogen implant with the nitridation associated with growing other oxides. Nitric oxide (NO) annealing of 28-/spl Aring/ oxides grown on nitrogen-implanted silicon results in the decrease of NMOS threshold voltage and in the increase (absolute value) of PMOS threshold with decreasing width. This effect arises from the positive charge from NO anneal interacting with the parasitic transistor associated with the shallow trench isolation edge recess. The parasitic impact becomes more pronounced for narrower widths due to higher effect of recess on total transistor width.