Deformation

Large-scale periodic undulations within the oceanic and continental lithospheres revealed by a number of observations, are often treated as compressive instabilities, i.e. lithospheric buckling or folding. These undulations are normally associated with intensive faulting, which raises questions on the role of faulting in the folding process, and even on the possibility of folding in highly faulted media. In this study, we demonstrate that folding can "survive" faulting and that both processes may develop concurrently, so that faulting may serve as a mechanism of folding in the brittle domain. We support this hypothesis by direct numerical modeling. The results are compared with the data on three most prominent and well-known cases of the oceanic and continental folding-like deformation ("Indian Ocean" type, "Western Gobi (central Asia)" type and "Central Australian" type). We demonstrate that under reasonable tectonic stresses, folds can develop from faults cutting through the brittle parts of the lithosphere. The predicted wavelengths and nite growth rates are in agreement with the observations. We also show that within a continental lithosphere with thermotectonic age greater than 400 My, either a bi-harmonic mode (two superimposed wavelengths, crustal and mantle one) or a coupled mode (mono-layer deformation) of inelastic folding can develop, depending on the strength and thickness of the lower crust.

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.

A novel split beam model is introduced to account for the local effects at the crack tip of bi-material interface by modeling a bi-layer composite beam as two separate shear deformable beams bonded perfectly along their interface. In comparisons with analytical two-dimensional continuum solutions and finite element analysis, better agreements are achieved for the present model, which is capable of capturing the local deformation at the crack tip in contrast to the conventional composite beam theory. New solutions of two important issues of cracked beams, i.e., local buckling and interface fracture, are then presented based on the proposed split bi-layer shear deformable beam model. Local buckling load of a delaminated beam considering the root rotation at the delamination tip is first obtained. By considering the root rotation at the crack tip, the buckling load is lower than the existing solution neglecting the local deformation at the delamination tip. New expressions of energy release rate and stress intensity factor considering the transverse shear effect are obtained by the solution of local deformation based on the novel split beam model, of which several new terms associated with the transverse shear force are present, and they represent an improved solution compared to the one from the classical beam model. Two specimens are analyzed with the present model, and the corresponding refined fracture parameters are provided, which are in better agreement with finite element analysis compared to the available classical solutions.

This study presents a survey of deformation characteristics of the installed high-density polyethylene ͑HDPE͒ pipelines. Video and laser inspections are carried out on over 15,000 ft ͑4,572 m͒ of buried HDPE pipelines installed across the nation. Different types of deformation failure modes observed in the buried HDPE pipelines are identified in this paper. The results show that the majority of buried HDPE pipelines have deformations in excess of the commonly acceptable limits along multiple locations within each pipeline.

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In this paper, we present a 3-D localization method for a magnetically actuated soft capsule endoscope (MASCE). The proposed localization scheme consists of three steps. First, MASCE is oriented to be coaxially aligned with an external permanent magnet (EPM). Second, MASCE is axially contracted by the enhanced magnetic attraction of the approaching EPM. Third, MASCE recovers its initial shape by the retracting EPM as the magnetic attraction weakens. The combination of the estimated direction in the coaxial alignment step and the estimated distance in the shape deformation (recovery) step provides the position of MASCE in 3-D. It is experimentally shown that the proposed localization method could provide 2.0-3.7 mm of distance error in 3-D. This study also introduces two new applications of the proposed localization method. First, based on the trace of contact points between the MASCE and the surface of the stomach, the 3-D geometrical model of a synthetic stomach was reconstructed. Next, the relative tissue compliance at each local contact point in the stomach was characterized by measuring the local tissue deformation at each point due to the preloading force. Finally, the characterized relative tissue compliance parameter was mapped onto the geometrical model of the stomach toward future use in disease diagnosis.

Plain film imaging remains important for the diagnosis and surveillance of scoliosis, as well as for the detection of complications after surgery. Advances in CT and MR imaging have greatly improved the ability to detect or confirming nonidiopathic causes of scoliosis, including abnormalities within the spinal canal. Three-dimensional thinking has become more important in evaluating and understanding scoliosis.

Three full-scale tests with the imperfect ditch method are described. The imperfect ditch method involves installing a compressible inclusion above rigid culverts to reduce the vertical earth pressure. Superlight expanded polystyrene blocks are used as the compressible material. In the first test, the instrumented culvert was a 1.95-m diameter concrete pipe beneath a 14-m-high rockfill embankment. In the second test, a 1.71-m diameter concrete pipe was used beneath a 15-m-high rock fill, and in the third, the culvert is a cast-in-place concrete box culvert with a 2.0-m width beneath 11 m of silty clay. The culverts were built between 1988 and 1989, and the instrumentation measured earth pressure, deformation, and temperature. The full-scale measurements show considerable reduction in the vertical earth pressure: that on top of the pipes in the granular fill was reduced to less than 30 percent of the overburden and that on the box culvert beneath the clay fill was reduced to less tha...

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Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerogra...

Outcome study to determine the internal consistency, and validity of adapted Turkish version of Scoliosis Research Society-22 (SRS-22) Instrument. To evaluate the validity and reliability of adapted Turkish Version of SRS-22 questionnaire. The SRS-22 questionnaire is a widely accepted questionnaire to assess the health-related quality of life for scoliotic patients in the United States. However, its adaptation in languages other than the source language is necessary for its multinational use. Translation/retranslation of the English version of the SRS-22 was done, and all steps for cross-cultural adaptation process were performed properly by an expert committee. Later, SRS-22 questionnaires and previously validated Short Form-36 (SF-36) outcome instruments were mailed to 82 patients who had been surgically treated for idiopathic scoliosis. All patients had a minimum of 2 years follow-up. Fifty-four patients (66%) responded to the first set of questionnaires. Forty-seven of the first...

The objective of this review article is to provide a concise discussion of atomistic modeling efforts aimed at understanding the nanoscale behavior and the role of grain boundaries in plasticity of metallic polycrystalline materials. Atomistic simulations of grain boundary behavior during plastic deformation have focused mainly on three distinct configurations: (i) bicrystal models, (ii) columnar nanocrystalline models, and (iii) 3D nanocrystalline models. Bicrystal models facilitate the isolation of specific mechanisms that occur at the grain boundary during plastic deformation, whereas columnar and 3D nanocrystalline models allow for an evaluation of triple junctions and complex stress states characteristic of polycrystalline microstructures. Ultimately, both sets of calculations have merits and are necessary to determine the role of grain boundary structure on material properties. Future directions in grain boundary modeling are discussed, including studies focused on the role of...

A number of lode-gold occurrences are hosted by hydrothermally altered greenstones along the southern boundary of the Palaeoproterozoic Central Lapland Greenstone Belt. The hydrothermally altered and mineralised zones are related to a major thrust and shear zone system that extends much across northern Finland. Spatial correlation between mineralized zones, brittle structural features and chemical alteration was explored and identified from high-resolution aeromagnetic data, in combination with airborne electromagnetic and gamma-ray spectrometric data and coupled with petrophysical and palaeomagnetic studies. The most prominent magnetic, ductile signatures formed during the Svecofennian Orogeny (1900-1800 Ma), resulting in elastic, curved, continuous magnetic patterns. These elastic anomaly patterns were disturbed by tectonic stress from S-SW, resulting in parallel, regularly oriented fracture families and thrust faults normal to the main stress direction. According to aeromagnetic, palaeomagnetic and structural evidence, the thrust zone was active during the latest stage of the orogenic event, but was also reactivated at a later date. Airborne gamma-ray data reveals zones of potassic alteration in the ultramafic rock units in the vicinity of cross-sections of these two fault sets. Chemical and mineralogical changes during alteration and metamorphism strongly affected the mafic and ultramafic host rocks throughout the deformation zone. The strong potassium enrichment and coinciding destruction of magnetic minerals resulted in enhanced potassium concentration and reduction of magnetic anomaly amplitudes. Palaeomagnetic results indicate that the remanent magnetization for the altered ultramafic rocks along the thrust zone is of chemical origin (CRM) and was acquired at 1880-1840 Ma, which is presumed also to be the age of the chemical alteration related to gold mineralization.

Nuts of four hazelnut varieties and five new selections used for table consumption were compressed at the moisture content of 6% wet basis to measure shell resistance to breakage. Rupture force, rupture energy and nut specific deformation were measured under three compression loading positions. Physical parameters of nuts were also evaluated to relate them to the data obtained by compression test measurements. Rupture force and nut specific deformation are the most discriminant parameters that can be used to describe the behaviour under compression, while rupture energy values show fewer differences among the considered varieties. The values of force required to break nut shell ranged from 322.2 to 769.3 N. The lowest values of force were generally obtained along the y-axis, the transverse axis containing the major dimension at right angles to the longitudinal axis. Nut specific deformation ranged from 3.35 to 11.76%. Correlations between physical and texture parameters showed that values of force, energy and deformation were dependent on different parameters that varied in the three considered axis. The most used varieties, Ennis and Barcelona, showed high mean values of force rupture to break shell and low deformability, while Tonda Giffoni and Tonda Bianca were easy to break. Among the new selections, L35 and B6, with mean values of force rupture less than 428 N and values of nut specific deformation higher than 8%, were suitable for table consumption.

Background: We have conducted a prospective study to investigate the relationship between cervical spine alignment and clinical outcome in 102 patients undergoing anterior contralateral microdiskectomy without interbody graft or cage. Methods: Preoperative and postoperative lateral cervical radiographs were obtained, and curvature of the surgically treated spinal segments and the overall curvature of the cervical spine were evaluated in all patients. Clinical outcomes were assessed using the NDI and SF-36. Results: There was no significant change in the mean overall cervical curvature (C2-C7) angles postoperatively in late follow-up findings ( P = .72). It represented a statistically significant mean loss of 2.738 of segmental lordosis ( P b .0001). The NDI scores decreased significantly in both early and late follow-up evaluations, and the SF-36 scores demonstrated significant improvement in late follow-up results in our series. Analysis of clinical outcome showed no statistical differences between patients with segmental lordosis or kyphosis. Conclusion: Despite the kyphosis seen at the treated levels, the overall alignment between C2 and C7 did not change significantly, indicating that the untreated segments of the cervical spine were compensating for focal kyphosis. D

Sulfonamide antibiotics are persistent pollutants of aquatic bodies, known to induce high levels of bacterial resistance. We investigated the adsorption of sulfadiazine, sulfamethazine, and sulfachloropyridazine sulfonamides into a highly dealuminated faujasite zeolite (Y) with cage window sizes comparable to sulfonamide dimensions. At maximal solubility the antibiotics were almost completely (>90%) and quickly (t < 1 min) removed from the water by zeolite. The maximal amount of sulfonamides adsorbed was 18-26% DW of dry zeolite weight, as evidenced by thermogravimetric analyses and accounted for about one antibiotic molecule per zeolitic cage. The presence of this organic inside the cage was revealed by unit cell parameter variations and structural deformations obtained by X-ray structure analyses carried out using the Rietveld method on exhausted zeolite. The most evident deformation effects were the lowering of the Fd-3m real symmetry in the parent zeolite to Fd-3 and the remarkable deformations which occurred in the 12-membered ring cage window after sulfadiazine or sulfachloropyridazine adsorption. After sulfamethazine adsorption, zeolite deformation caused a lowering in symmetry up to the monoclinic P2/m space group. The effective and irreversible adsorption of sulfonamides into organophylic Y zeolite makes this cheap and environmentally friendly material a suitable candidate for removing sulfonamides from water.

Fast, realistic physically based deformable models are required for real time Virtual Reality applications such as surgical simulators. The main focus of this paper is to introduce a new deformable model called NDM that is fast enough to allow interactive frame rates and plausible deformation. The NDM is integrated in an interactive Cataract Eye Surgery Simulator (CESS), which is used to model the deformation of eye tissues when it is manipulated with surgical instrument. The deformation is modelled as the transmission of the force from the manipulated vertex to its adjacent neighbors and from those neighbors to their neighbors and so on, also the deformation can be simulated locally or globally. The NDM is tested on virtual objects those modeled as a surface mesh. The model is implemented in C programming language and uses GLUT and GLUI for the graphical user interface, OpenGL for visualization, and runs on a single personal computer. The simulation results obtained from the proposed NDM shows that the later outperform the traditional mass spring model in term of computational time. Keywords—Deformation, Soft tissue modelling, surgery simulation.

: This research aims to develop, analyze, and evaluate a new type of structural element that will enhance the crashworthiness of naval vehicles by providing outstanding energy absorption with minimal weight. The structural element is an array of concentric fiber reinforced composite tubes with extension-twist coupling and ultra-high Poisson&#39;s ratio. The tubes are configured to crush or shear internal foam as a means of absorbing energy. This interim report includes technical progress, plans, publications, and various administrative matters. In the current period, work has focused on evaluating the mechanisms of energy absorption in composite tubular structures and the development of analytical models for predicting the deformation and damage in these tubular structures. A significant effort was dedicated towards developing the manufacturing and testing technology for tubes having extension-twist coupling. This effort culminated in the successful demonstration, for the first time...

The lower part of the Carboniferous Shannon Basin of Western Ireland contains a deep-water succession which exceeds 1200 m in thickness that comprises five lithologically different units deposited within a confined, relatively narrow basin: (i) a calciclastic debris-flow and turbidite unit formed by resedimentation from nearby carbonate platforms, (ii) a siliciclastic black shale succession with former source potential which onlaps basin margins (Clare Shales), (iii) a sandstone-dominated turbidite formation, controlled by ponded accommodation and deposited axially in the basin (Ross Formation), (iv) a mudstone-rich turbidite-bearing succession, which onlaps basin margins (lower Gull Island Formation), and (v) a mudstone-dominated prograding slope succession (upper Gull Island Formation and lower Tullig Cyclothem), which grades transitionally upwards into deltaic deposits. The top unit records progradation at a time when basin differential subsidence had diminished significantly and local basin topography did not control deposition. The two upper mudstone-dominated units are different in terms of both sandstone content and their genetic significance within the overall basin-fill, and their potential relevance as reservoir analogues. The lower part of the Gull Island Formation contains three principal facies associations: (a) shallow turbidite channels and sheets representing channel margin and levee deposits, (b) mud-rich slumps, and (c) less than 1 m thick, rare, hemipelagic shales. More than 75% is deformed by soft-sediment deformation, but only to a smaller degree affecting sandstone units. The turbidites record transport to the ENE, along the axis of the basin, while the slumps were derived from an unstable northern slope and transported transversely into the basin towards the southeast. The distribution of turbidite sandstone and slumps is inversely proportional. Sandstones decrease in importance away from the basin axis as slumps increase in number and thickness. The lower part of the Gull Island Formation is interpreted to record progressive fill of a deep basin controlled by local, healed slope accommodation with onlap/sidelap of the basin margins. The instability resulted from a combination of fault-controlled differential subsidence between basin margin and basin axis, and high rates of sedimentation. The upper part of the Gull Island Formation is entirely dominated by mudstones, which grade upwards into siltstones. It contains rare, up to 15 m thick, isolated channels filled by turbidites, showing transport towards the east. The upper part records easterly progradation of a deepwater slope genetically tied to overlying deltaic deposits, and controlled by regional accommodation. The contrasts between the lower and upper parts of the Gull Island Formation show that onlapping/sidelapping turbidite successions have reservoir potential near basin axes, but that prograding deep-water slopes are less likely to have reservoir potential of significance. A suggested regional downlap surface between the two parts is a significant break and marker in terms of reservoir potential.

This work presents results for the three-dimensional displacement field at Tenerife Island calculated from campaign GPS and ascending and descending ENVISAT DInSAR interferograms. The goal of this work is to provide an example of the flexibility of the technique by fusing together new varieties of geodetic data, and to observe surface deformations and study precursors of potential activity in volcanic regions. Interferometric processing of ENVISAT data was performed with GAMMA software. All possible combinations were used to create interferograms and then stacking was used to increase signal-to-noise ratio. Decorrelated areas were widely observed, particularly for interferograms with large perpendicular baseline and large time span. Tropospheric signal was also observed which significantly complicated the interpretation. Subsidence signal was observed in the NW part of the island and around Mount Teide and agreed in some regions with campaign GPS data. It is expected that the technique will provide better results when more high quality DInSAR and GPS data is available.

This paper is concerned with the mechanics of interfacial fracture that are active in two common testing configurations of solder joint reliability. Utilizing eutectic Pb-Sn/Cu as a reference system and assuming the presence of a predefined crack size in the intermetallic compound (IMC) layer, stress intensity factors (K I and K II) at the crack are numerically calculated for the two given configurations. The analysis of the tensile test configuration reveals that the fracture occurs by the crack-opening mode (K I mode), as anticipated, but that it is greatly assisted by the viscoplasticity of the solder. With nonuniform viscoplastic deformation across the joint, K I is found to increase much more rapidly than it would without the solder, decreasing the critical crack size to the micron scale. The same mechanism is also responsible for the development of a K II comparable to K I at the crack tip, that is, |K I /K II | $ 1. It is also found that the predominant fracture mode in the bump shear configuration is crack opening, not crack shearing. This is an unexpected result, but numerical analyses as well as experimental observations provide consistent indications that fracture occurs by crack opening. During shear testing, bump rotation due to nonzero rotational moment in the test configuration is found to be responsible for the change in the fracture mode because the rotation makes K I become dominant over K II. With rotational moment being affected by the geometry of the bump, it is further found that the fracture behavior may vary with bump size or shape.

Several laterally offset and aggradational sinuous submarine channels are contained within a 54 km long segment of the Benin-major Canyon. Axial channel deposits produce high amplitude reflections on three-dimensional (3-D) seismic profiles. Some seismic reflections have U-or V-shaped cross-sectional motifs that were correlated with confidence along linear to meandering paths for distances up to 70 km. They are referred to here as channel-forms (CFs), and are believed to be the axial parts of submarine channels preserved during overall channel floor aggradation. A total of 15 separate CFs were mapped allowing thalweg-gradients, dimensions, and morphology to be studied spatially and through time, providing insight into how submarine canyons fill. Their planform geometry evolved predominantly in a stepwise fashion through alternating periods of cut-and-fill, but more gradual channel migrations are also observed. The largest offsets in successive channel floor position occur after periods of significant vertical CF fill ('thalweg plugging'-with deposits commonly consisting of lower amplitude, transparent to chaotic seismic reflections). The passage of erosive flows after such periods of fill caused abrupt shifts in channel position, particularly at meander bends, with increased potential for the formation of pseudo meander loop cut-offs. Significant spatial differences in the stacking architecture of CFs are attributed to local slope deformation and perhaps also to a recent channel avulsion just west of the study area. Abrupt channel straightening in the western study area coincides with a period of increased valley-gradient associated with amplification of an underlying anticlinal fold. The youngest CFs in this area show limited aggradation and are characterized by repeated episodes of headward erosion causing knickpoint migration as the recent channel floor tried, unsuccessfully, to establish a smooth graded depth profile. This is in stark contrast to the time-equivalent predominantly aggradational CFs in the eastern study area that show a progressive increase in sinuosity through time. r

The biomechanics of skin and underlying tissues plays a fundamental role in the human sense of touch. It governs the mechanics of contact between the skin and an object, the transmission of the mechanical signals through the skin, and their transduction into neural signals by the mechanoreceptors. To better understand the mechanics of touch, it is necessary to establish quantitative relationships between the loads imposed on the skin by an object, the state of stresses/strains at mechanoreceptor locations, and the resulting neural response. Towards this goal, 3-D finite-element models of human and monkey fingertips with realistic external geometries were developed. By computing fingertip model deformations under line loads, it was shown that a multi-layered model was necessary to match previously obtained in vivo data on skin surface displacements. An optimal ratio of elastic moduli of the layers was determined through numerical experiments whose results were matched with empirical ...

One of the largest long-runout landslides in the modern history of the Czech Republic originated on the southern slopes of the Girová Mountain (Outer Western Carpathians) at the end of extreme rainfalls in May 2010. The structurally predisposed Girová Mountain rockslide occurred very quickly within fault-weakened, deeply-weathered flysch bedrock. Its main phase, during which a wedge-like block collapsed in the upper part of slope, lasted for a few hours. The overloaded slope collapsed and its motion lasted for the following 3 days. The May 2010 Girová Mountain rockslide is an excellent case of a recurrent long-runout landslide nested within a deep-seated gravitational slope deformation with a long history of Late Quaternary mass movements. The chronology of slope failures within the studied slope was reconstructed by means of radiocarbon dating and dendrogeomorphological analysis. At least one Holocene long-runout landslide (7.4 cal ka BP) and several smaller failures (~1.5 and~0.6 cal ka BP) preceded this recent catastrophic failure. Dendrogeomorphological analysis showed that the failure had been preceded by at least 80-year-long creep movement that accelerated over the years due to extreme rainfall events. Despite the fact that extreme precipitation of May 2010 represented the last incremental change before catastrophic collapse of the slope, its main reason was gradual weakening of rock massif and concentrated creeping (with some accelerated phases) in the upper part of the slope deformation.

Progress in the Finnish breeding programme for rainbow trout was assessed by estimating genetic trends in growth, maturity age and skeletal deformations and by calculating rates of inbreeding and additive genetic relationships. The analysis included two pedigreed populations with three generations and over 117,000 individuals recorded for skeletal deformations, growth and age at maturity. Because the breeding station is located in fresh water but sea is the main production environment, each family was split into subgroups to be tested for performance either in fresh or sea water. Estimation of breeding values across the generations showed that multitrait selection has produced an average of 7% genetic gain per generation in fresh and sea water growth of market-sized fish. In the population with high frequency of early maturing males, phenotypic culling of early maturing males has prevented an increase in the frequency of early maturing fish. In the other population, the frequency of early maturing females has increased, the genetic change being unfavourable. Weak favourable or no correlated genetic changes were observed in the frequency of deformations in response to selection for the production traits. Rate of inbreeding has remained low, the maximum value being 0.7% per generation. Because mating of close relatives has been avoided, an increase in coefficient of additive genetic relationships describes the risk of the programme more realistically than rate of inbreeding. The average increase in relationship was 0.7% per generation, a value below the suggested precaution level.

Steel-fiber-reinforced polymer (FRP) composite bars (SFCBs) are a novel reinforcement for concrete structures. Because of the FRP's linear elastic characteristic and high ultimate strength, they can achieve a stable postyield stiffness even after the inner steel bar has yielded, which subsequently enables a performance-based seismic design to easily be implemented. In this study, lateral cyclic loading tests of concrete columns reinforced either by SFCBs or by ordinary steel bars were conducted with axial compression ratios of 0.12. The main variable parameters were the FRP type (basalt or carbon FRP) and the steel/FRP ratio of the SFCBs. The test results showed the following:

In a thin and large area PZT-ceramics piezoresonator (PR) with relatively low resonance impedance, caused by high-frequency resonance and high PR capacitance, the effect of electrode resistivity and parasitic resistive and inductive elements in the measurement fixture results in significant distortion of the measured thickness-mode (longitudinal TL, shear TS) resonance response-resonance frequency shifts and characteristics deformation. This distortion may not allow the precise measurement of the PR characteristic frequencies, quality factor, and electromechanical coupling coefficient so essential to a complete PR and material characterization. A theoretical description of the &quot;energy-trap&quot; phenomena in a thickness-vibrating PR with resistive electrodes is presented. To interpret electrical measurements, the electromechanical model, including for completeness both the PR with resistive electrodes (as a system with distributed parameters) and the measurement fixture, is dev...

Among the vulcanized elastomers, the chloroprene rubber (DuPont Neoprene®-generic name) possesses a good performance, being one of the most used in the current days. However, this kind of polymer causes a serious environmental problem if it is not reprocessed or recycled. A worldwide method that has been used and that is an important tool in the rubber devulcanization is microwave irradiation at high temperature Elastomer waste may be devulcanized without depolymerization and allows a new vulcanization into a product having physical properties essentially equivalent to the original vulcanized. In this work, the chloroprene samples were irradiated in microwave generator equipment with 2,450MHz (frequency) and 1,000W to 3,000W (power). The properties of samples (according to ASTM standards) were analyzed before and after irradiation. The degraded material after irradiation will be tested for re-use.

Long Valley Caldera is an active volcanic region in east central California. Surface deformation on the resurgent dome within the caldera was an order of magnitude higher for the ®ve-month period September 1997 through January 1998 compared to the previous three-year average. However, the location of the immediate (shallow) source of deformation remained essentially constant, 5±7 km beneath the dome, near the top of a region of probable magma accumulation de®ned by seismic data. Similarly, although the rate of seismic moment release increased dramatically, earthquake locations remained similar to earlier periods. The rate of deformation increased exponentially between April±May 1997 and late November 1997 with a time constant of ,55±65 days, after which it decreased exponentially with about the same time constant. We develop a model consistent with these observations and also consistent with independent constraints on sub-surface rheology from thermal, geochemical and laboratory data. Deformation at sites on the resurgent dome most sensitive to the shallow deformation source are well ®t by a model with a single pressure source at 6 km depth which experienced a pressure pulse that began in late 1996, peaked in November 1997, close to the time of major seismic moment release, and essentially ended in mid-1999. The pressure source in our model is surrounded by a 1 km thick ªshellº of Maxwell viscoelastic material (shell viscosity 10 16 Pa s) within an elastic half space, and has peak values that are much lower than corresponding purely elastic half space models. The shell viscosity is characteristic of a weak, deformable solid, e.g. quartz-bearing country rock surrounding the magma chamber at temperatures in the range 500±6008C, i.e. above the brittle±ductile transition, and/or largely crystallized rhyolite near its solidus temperature of ,6708C, material that probably exists near the top of the zoned magma chamber at Long Valley. q (T.H. Dixon). Fig. 4. Seismicity at Long Valley for November 1997. Inset shows all events in map view projected onto a west-east cross section. Note well-de®ned linear trend, which may indicate location of a dike or fault near the south moat.

Disturbances of the cerebrospinal fluid (CSF) flow in the brain can lead to hydrocephalus, a condition affecting thousands of people annually in the US. Considerable controversy exists about fluid and pressure dynamics, and about how the brain responds to changes in flow patterns and compression in hydrocephalus. This paper presents a new model based on the first principles of fluid mechanics. This model of fluid-structure interactions predicts flows and pressures throughout the brain's ventricular pathways consistent with both animal intracranial pressure (ICP) measurements and human CINE phase-contrast magnetic resonance imaging data. The computations provide approximations of the tissue deformations of the brain parenchyma. The model also quantifies the pulsatile CSF motion including flow reversal in the aqueduct as well as the changes in ICPs due to brain tissue compression. It does not require the existence of large transmural pressure differences as the force for ventricular expansion. Finally, the new model gives an explanation of communicating hydrocephalus and the phenomenon of asymmetric hydrocephalus.

In evaluation of genu varum-genu valgum, tibiofemoral (TF) angle and intercondylar (IC) or intermalleolar (IM) distance are commonly measured. In this study, we determined mean values and normal limits for TF angle and IC/ IM distance in 590 normal Turkish children (287 girls and 303 boys) aged from 3 to 17 years using clinical methods. We noted a significantly higher degree of valgus angle than that in previous reports. The maximal mean valgus angle was 9.6 degrees at 7 years for boys and 9.8 degrees at 6 years for girls. These differences were considered racial differences between Turkish children and those of other races. Turkish children, aged between 3 and 17 years, exhibited Յ11 degrees physiologic valgus. A measurable varus angle or a valgus higher than 11 degrees during this period should be considered abnormal.

Background: The definition of normal values of left ventricular global longitudinal strain (GLS), global circumferential strain, and global radial strain is of critical importance to the clinical application of this modality. The investigators performed a meta-analysis of normal ranges and sought to identify factors that contribute to reported variations.

The present work was concerned with the effect of sensitization and deformation on the corrosion behavior of 304LN and 316LN austenitic stainless steel before and after hot rolling. Specimens were subjected to mechanical deformation and heat treated at 650 o C for 5hrs, 6.5 hrs and 8 hrs. Detailed micro-structural analysis using optical metallurgical microscope and hardness testing by Vicker's hardness tester were carried out to investigate the hardness of the specimens. X-ray Diffraction (XRD) was used to explain the phenomena qualitatively. The electrochemical technique such as the potentiodynamic cyclic polarization measurement was performed to investigate and analyze pitting and protection corrosion resistance properties and also double loop electrochemical potentio-kinetic reactivation measurement technique was also performed for detecting degree of sensitization.

The U.S. military requires the ability to rapidly deploy troops, equipment, and materials anywhere in the world. Recent operations have brought attention to the need to utilize austere, unsurfaced, and sometimes sub-standard airfields within a theater of interest. These airfields may require additional taxiways and aprons. One option for the rapid construction of such is airfield matting systems. The focus of the work for this thesis was commercially available airfield matting systems to support large military transport aircraft, such as the C-17. Several test sections with differing strength soils were built with chosen mats tested in an elimination method, using a load cart that simulates contingency loading of one main gear of the C-17. Matting systems were evaluated based on logistical and assembly requirements, and deformation and damage sustained during traffic. A modeling effort was performed to investigate the potential of a simple model to predict the response of these matting systems under full-scale testing.

In conventional thermal spraying, the spray particles are partially or fully molten when they deposit on the substrate. Cold spraying, in contrast, uses less thermal and more kinetic energy. In this process, solid particles impact on the substrate at high velocities and form excellent coatings. Due to comparatively low temperatures and typically inert process gases, cold spraying is particularly suitable for heat and oxidation sensitive materials. In recent years, modeling and computational methods have been widely used to study this relatively new spraying process, particularly to describe impact conditions of particles, to improve nozzle design, and to provide a better understanding of the thermo-mechanical processes that lead to particle bonding and deposition. This paper summarizes the state of the art in these theoretical studies, alongside a comprehensive description of the process. The paper also discusses the prediction of coating properties in the light of modeling combined with experimental investigations.

Compared with simply supported beams, continuous steel-concrete composite beams have many advantages such as higher span/depth ratio, less deflection, and higher fundamental frequency of vibration due to its higher stiffness. However, in negative bending regions near interior supports, tension in concrete is unfavorable and a complicated issue, which deserves a special study. In this paper, a mechanics model based on elastic theory was established to investigate the stiffness of composite beams in negative bending regions by considering slips at the steel beam-concrete slab interface and concrete-reinforcement interface. In order to validate this approach, a test of three composite beams with profiled sheeting under negative bending was conducted. Meanwhile, a three-dimensional nonlinear finite element (FE) analysis was conducted to investigate the general behavior of the tested specimens. In addition, a comparative analysis between results derived from the analytical model, laboratory test, and FE analysis was performed. The results show that slip always exists for composite beams under negative bending even with complete shear connection (full composite action) between the steel and concrete components. The slip effect results in an additional curvature of beam bending and reduces the section stiffness by 10-20% compared with that of a beam without any slip in serviceability condition. This reduction should be considered in designing process especially for cantilever beams. Formulae under other loading cases and boundary conditions were also proposed. The results can serve as a basis for further study on stiffness of continuous steel-concrete composite beams and can directly be used for the deflection calculation of cantilever beams.

Three-dimensional seismic mapping of interpretative sub-surface time slice sections, incorporating age data and detailed structural observations places constraints on the structural architecture and stratigraphic evolution of the Icotea pull-apart basin in the central Maracaibo basin, Venezuela. All four fault-bounded sides of the Icotea basin, its ,3-km-thick Eocene basin fill of clastic sediments and faults pre-dating the opening of the basin can be mapped in three dimensions. The development of the Icotea basin provides an excellent observational basis for understanding the structural history of three sets of regionally extensive faults and testing two models for the formation of pull-apart basins in general. Three main fault trends produced at different periods in the formation of the Cretaceous-Recent Maracaibo basin are mapped using 3D seismic data in the central part of the basin: (1) N-NE-striking normal faults, including the Icotea fault; these faults formed originally during Late Jurassic-Early Cretaceous rifting and reactivated as left-lateral strike-slip faults during late Paleocene-Eocene convergent deformation between the Caribbean and South American plates; (2) NW striking faults formed by late Paleocene-Eocene overthrusting of the Caribbean plate and downward flexure of the South American plate to create a major foreland basin depocenter; and (3) NE-striking normal faults, of pre-Cretaceous age, were reactivated during late Paleocene-Eocene plate convergence. Three-dimensional architecture of the Icotea basin interpreted from five time slices through the basin and its flank areas supports the simple pull-apart model for the Eocene opening of the Icotea basin. The amount of extension across the suite of normal faults ranges between 0.8 and 2.25 km. This range of offset is consistent with some previous estimates of minor left-lateral displacement along the Icotea fault but is inconsistent with either low-angle or high-angle thrusting during Eocene time, as inferred from previous interpretations of widely spaced two-dimensional seismic lines. The normal faults that formed the pull-apart basin reactivated pre-existing faults due to plate flexure.

Half warm mix asphalt recycling (HWMR) is a promising new technique for reclaimed asphalt pavement (RAP) recycling under development in Portugal. The technique is based in mix recycling RAP at low temperatures, between 70ºC and 100ºC. An attempt to apply this technique was made for the first time at EN 244 road, in the stretch between Ponte de Sôr and close to Gavião. The project was initially conceived by " Direcção de Estradas de Portalegre ". The solution was found to be most appropriated for the rehabilitation of the existing asphalt pavement, both from the economical and environmental points of view. Although initially the mixing temperature was supposed to be between 70ºC and 100ºC, higher mixing temperatures were adopted later, during plant production, therefore Warm Mix Recycling (WMR) was used instead of HWMR.. This paper presents the preliminary results of a research project concerning design and performance of WMR / HWMR, using the mix asphalt recycling technique applied at EN244 road as a case study. The aim of this preliminary research work is to recommend design parameters for half warm mix asphalt recycling,. Tests were preformed using laboratory compacted specimens and specimens extracted directly from the pavement in order to establish a mix design criteria (Marshall Stability, Immersion-compression test and Stiffness) and mix performance (Resistance to fatigue with four-point bending test on prismatic shaped specimens and Permanent deformation with Wheel Tracking).

A great amount of work has been done over the past few years to understand the structure–properties relationship in polypropylene/glass fiber composites. This is because of the very fast-growing rate of polypropylene applications in the automotive and other industries. This work focused on the role of glass fibers and fiber–matrix adhesion on deformation mechanism. Composites with different fiber content, with and without adhesion promoter, were fabricated. Tensile tests and microscopy techniques were conducted. Based on the results, a physical model has been proposed that illustrates the initiation and growth of the damage under static loading condition. According to this work, the introduction of glass fibers shifts the deformation mechanism from shear yielding to crazing. Although crazes propagate in a different manner in composites containing standard and treated fibers, no influence of interfacial adhesion was observed on craze thickening phenomenon. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2171–2176, 2003

This Finite element method is one of the most advanced calculating methods for approximation of accurate solutions to engineering problems. Optimization of grab's quay cranes is necessary because most port operators use this type of equipment for loading and unloading bulk cargo. Initial research methods applied in this study are based on observations and surveys conducted on Bocşa 16 t -32 m mobile quay cranes of MinMetal S.A. Constanta port operator. Modeling and analysis for grab's structure optimization was made with FEMAP and NX

A long-term retrospective review of a long oblique distal osteotomy of the fifth metatarsal for correction of a tailor's bunion deformity is presented. The technique, results, and follow-up of this procedure are described. The long oblique distal osteotomy was performed on 25 feet on 16 patients. Follow-up ranged from 11 to 110 months with an average of 64.4 months. The average preoperative intermetatarsal 4-5 angle and lateral deviation angle improved from 10.88°and 4.24°, respectively, to 5.52°and Ϫ4.24°p ostoperatively, respectively. A modified scoring scale for lesser metatarsal procedures was used, showing an average postoperative score of 94 out of 100 possible points. Subjectively, 96% (24 of 25) of feet that underwent surgery were rated as excellent or good. Complications included one patient with paresthesias, one soft-tissue infection, and 2 patients had irritation from screws. The authors conclude that the long oblique distal osteotomy is a viable alternative in the correction of tailor's bunion deformity.