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The impact of Cl on alkali-induced high-temperature corrosion of stainless steels/FeCrAl alloys after breakaway oxidation was investigated in a simulated biomass- and waste-fired boiler environment at 600 °C. For this investigation, three alloys were exposed to low Cl load environment (H2O+KCl) and to high Cl load (H2O+KCl+HCl). Post-exposure analysis showed that the stainless steel SVM12 experiences fast oxidation and forms thick double-layered Fe-rich oxide scales. The corrosion attack is further accelerated with addition of HCl for this material with the effect being more pronounced in the inward-growing scale. The FeCrAl and FeCrNi alloys exhibit slower oxidation kinetics after the breakaway corrosion compared to SVM12 in the H2O+KCl exposure. Furthermore, in contrast with SVM12, the addition of HCl did not accelerate the corrosion attack on these alloys. It is argued that the properties of the secondary oxide layer formed after breakaway corrosion are important in the continued corrosion resistance against chlorine-induced corrosion attack. Especially, the Cr content in the inner scales is suggested to be important in corrosion mitigation. [ABSTRACT FROM AUTHOR]

This paper presents finite-element simulations to reinterpret a series of full-model and particle image velocimetry (PIV) (half model) centrifuge tests to study the uplift of skirted foundations. The focus is on the influence of uplift rate on the uplift capacity and the mechanism of breakaway (i.e., the phenomenon of sudden loss of uplift resistance). A backbone curve, quantifying the uplift rate-capacity relationship, is established for uplift based on the numerical and experimental results. The dimensionless velocities V=6 and 130 are found to be the boundaries for drained, partially drained, and undrained conditions. The breakaway is found related to ambient water infiltration. In the numerical modeling, the remaining length of the skirt inside soil is used as an indicator for breakaway, i.e., breakaway happens when this length is smaller than a critical value. This hypothesis is demonstrated to be effective by comparing the numerical modeling with the experimental results. [ABSTRACT FROM AUTHOR]

This paper presents the detailed formulation of a coupled hydro‐mechanical structure‐soil interface and demonstrates its application in simulating uplifting problems. This interface features real‐time prediction of the pore pressure generation and structure‐soil separation, and thus rate dependency and 'breakaway' can be modeled without user intervention. Constitutive relations of this interface were derived by considering the coupling between soil skeleton and fluid along the interface. A complete finite element formulation and numerical implementation of the interface is provided based on an eight‐node element. The performance of this interface is demonstrated by simulating lifting a surface footing at varying rates (spanning across undrained, partially drained and drained conditions), compared with existing theoretical solutions, numerical results and experimental data. The good agreement achieved indicates that this interface is capable of modelling uplift at varying rates, which is an extremely challenging topic in offshore engineering. Sensitivity studies were conducted to investigate the parameters affecting uplifting behaviour. A unified backbone curve was established correspondingly, which is shown to be different from existing studies in compression, due to the difference in the mechanism between the two cases. [ABSTRACT FROM AUTHOR]

Zircaloy-4 isothermal oxidation tests were conducted at 1000 °C under an oxygen atmosphere with flow rates varying from 20 to 200 mL/min. In this research, a breakaway time delay phenomenon was discovered. The temperature of the atmosphere near the cladding was measured in order to estimate the oxidation rate and identify the condition of the phenomenon. A sharp escalation in the cladding temperature was observed in the early stage of oxidation as the flow rate increased. In addition, macroscopic and microscopic observations were performed to identify the effects of initial temperature escalation. The results showed that the thickness of the dense columnar oxide increased in the oxide scale when the initial peak temperature exceeded 1050 °C. Based on these observations, it can be assumed that temperature escalation in the early stage can influence the thickness of dense oxides, and this in turn affects the oxidation behaviors, especially the breakaway time. [ABSTRACT FROM AUTHOR]

This paper examines the oxidation behavior of thin specimens of cast NiCoCrAlY alloys at 1150 ∘ C through successive stages, from Al 2 O 3 growth to complete alloy conversion to oxide. Five alloy compositions were used, with varying fractions and compositions of γ and β . The time evolution of the alloy composition during Al 2 O 3 growth was simulated using the DICTRA module of Thermo-Calc and calculated analytically in the approximation of flat profiles. Simulated and experimental profiles were found to be in good agreement, indicating that the phase equilibrium and mass balance were correctly reproduced in the simulations. Local variations of alloy composition were observed in thinner specimens and found to be comparable with the variations expected from the uncertainty on the initial specimen thickness. The variations observed in the time-to- Al 2 O 3 failure were greater than expected on this basis, suggesting that additional sources of variability were in effect. Alumina failure was followed by the growth of a Cr 2 O 3 layer at the alloy–scale interface. Similarly, Cr consumption eventually led to Cr 2 O 3 failure, and Ni- and Co-containing spinel oxide formed, converting the Cr 2 O 3 at the alloy–scale interface and the Al 2 O 3 at the scale–gas interface. The remaining NiCo alloy was then converted to (Ni,Co)O. This sequence occurred without abrupt increase in the mass gain, due to the continued presence of the remnant Al 2 O 3 layer, and to the small amount of metal left to oxidize when the (Ni,Co)O eventually broke through the scale. The evolution of the scale composition throughout the oxidation stages is discussed based on an analysis of the thermodynamic conditions at the alloy–scale interface. [ABSTRACT FROM AUTHOR]

The oxidation behavior of a nickel-based superalloy was investigated from 650 to 1,000 °C for up to 1,000 h in air. Samples with thicknesses ranging from 20 to 500 µm were used to document the evolutions of microstructure and oxide scale. Oxidation products and subsurface evolution of the metal microstructure were characterized by XRD and EDS analyses. Local breakaway was observed after 600 h at 800 °C and after 100 h at 900 °C due to the full consumption of Cr from the alloy. Room temperature tensile tests were performed on aged and pre-oxidized specimens with thicknesses ranging from 20 µm to 500 µm, at 800 °C. The results were compared to tensile tests performed on the as-received metallurgical state. Both size effects due to sample thickness reduction and to sample thickness/pre-oxidation width ratio were examined onto the mechanical behavior. Interestingly, the formation of TCP phases, the oxide layer and the subsequent Cr-depleted subsurface region from either aging or oxidation treatments impairs the mechanical integrity. Bulk and subsurface regions are impacted, especially for tens-of-micrometer thin samples. [ABSTRACT FROM AUTHOR]

The world governing body for cycling proscribed the use of two-way radio communication in road cycling races, with the ban set to become fully effective in 2012. The ban was instituted because radio use was perceived to have altered the cycling competitions by making outcomes more predictable and of less interest to sport’s consumers. This empirical analysis of the policy rationale considers the uncertainty of outcome hypothesis (UOH) as it applies to professional cycling races and creates a novel measure, the likelihood of breakaway success (LBS). The LBS is analyzed in 1436 bicycle races between 1985–2010 to examine potential changes in outcomes associated with the use of two-way radio technology by competitors and team directors. The data suggests that radio technology has had a significant association with event outcome types. The relevance of the findings to intraorganizational communication, management, and hierarchies of sports teams are also discussed. [ABSTRACT FROM AUTHOR]

Zircaloy-4 isothermal oxidation tests were conducted at 1000 °C under an oxygen atmosphere with flow rates varying from 20 to 200 mL/min. In this research, a breakaway time delay phenomenon was discovered. The temperature of the atmosphere near the cladding was measured in order to estimate the oxidation rate and identify the condition of the phenomenon. A sharp escalation in the cladding temperature was observed in the early stage of oxidation as the flow rate increased. In addition, macroscopic and microscopic observations were performed to identify the effects of initial temperature escalation. The results showed that the thickness of the dense columnar oxide increased in the oxide scale when the initial peak temperature exceeded 1050 °C. Based on these observations, it can be assumed that temperature escalation in the early stage can influence the thickness of dense oxides, and this in turn affects the oxidation behaviors, especially the breakaway time.

The rating of perceived exertion (RPE) normally grows as a scalar function of relative competitive distance, suggesting that it may translate between the brain and body relative to managing fatigue during time-trial exercise. In nonstandard pacing situations, a reciprocal relationship between RPE and power output (PO) would be predicted. Purpose: To determine whether PO would decrease when RPE was forced above the normal growth curve during a cycle time trial. Methods: Well-trained cyclists performed randomly ordered 10-km cycle time trials. In CONTROL they rode at their own best pace throughout. In BURST, they made a 1-km "burst" at the 4-km mark and then finished as rapidly as possible. Results: CONTROL was significantly (P < .05) faster than BURST (16:36 vs 17:00 min). During CONTROL, responses between 4 and 5 km were PO, 240 W; RPE, 5-6; and blood lactate [HLa], 8-9 mmol/L. During BURST PO increased to 282 W, then fell to 220 W after the burst and remained below CONTROL until the end spurt (9 km). RPE increased to 9 during the burst but returned to the normal RPE growth pattern by 6 km; [HLa] increased to -13 mmol/L after the burst and remained elevated throughout the remainder of the trial. Conclusions: The reciprocal behavior of RPE and PO after BURST supports the hypothesis that RPE translates between the brain and the body during heavy exercise. However, the continuing reduction of PO after the burst, even after RPE returned to its normal growth pattern, suggests that PO is regulated in a more complex manner than reflected solely by RPE. [ABSTRACT FROM AUTHOR]

The steam oxidation behavior of Zr-based Zircaloy-4 fuel cladding was studied at 1273 K with two different surface roughness levels. Steam was introduced either at room temperature (RT) or at 1273 K. Weight gain kinetics were evaluated by post-test weight measurement, and the reaction products and alloy microstructure were evaluated using optical microscopy. Hydrogen pick-up was measured by the gas extraction technique. Specimen surface roughness did not affect the oxidation kinetics or the hydrogen absorption. The time to breakaway oxidation was suppressed when steam was introduced at RT, and the oxide was more adherent, suggesting superior mechanical properties. When steam was introduced at 1273 K, an undulated oxide–metal interface formed earlier and a higher amount of hydrogen was absorbed by cladding before the kinetic transition. The alloy grain grew into larger size in the condition when steam was injected at 1273 K compared to the condition when steam was injected at RT, which may affect the observed behavior. After the oxide breakaway, the rate of hydrogen absorption accelerated substantially independent of the temperature of steam injection. [ABSTRACT FROM AUTHOR]

Effective implementation of the static friction of sliding isolators in object-oriented software for structural design has not yet been achieved, and use of the dynamic friction only for design is common practice. A modeling strategy to account for the contribution of static friction under unidirectional ground motion histories has been developed and used to assess its effects on the response of a building isolated with curved surface sliders. Under low-to-moderate intensity earthquakes, disregarding static friction can lead to unpredictable response of the isolation system and result in a non-conservative evaluation of accelerations and forces transferred to the superstructure. [ABSTRACT FROM AUTHOR]

• TG steam oxidation (600–1200 °C) done on Zr-2.5Nb and microstructure characterized. • Different microstructural features observed for tests in 600–900 °C and 900–1200 °C. • Breakaway oxidation and high hydrogen pick up observed at 1000 °C. • Discontinuity in the slope of parabolic rate constants with temperature seen at 900 °C. • Activation energy higher for tetragonal rich oxide than monoclinic rich oxide. Zr-2.5Nb pressure tube material was subjected to isothermal steam exposures in the range 600–1200 °C for different durations to predict its oxidation behavior during hypothetical accident scenarios. The oxidation exponent obtained from power law fitting of the thermogravimetry (TG) curves deviated from parabolic regime. Nevertheless, oxidation kinetics was described by determining the parabolic rate constants (K p) in two temperature ranges: K p = 0.029 exp(-111075/RT) (kg/m2)2/ sec for 600–900 °C whereas K p = 77652.6 exp(-254824/RT) (kg/m2)2/ sec for 900–1200 °C. In the tested durations, only the 1000 °C sample has shown breakaway transition, after approximately 105 min and has absorbed the highest amount of hydrogen amongst all samples. The trend in hydrogen pickup fraction (HPUF) was verified by two complementary hydrogen determination methods. Clear differences were identified in the α-Zr(O) layer formed on the samples below and above 900 °C. In the α + β range of 600–900 °C, α-Zr(O) consisted of tiny β precipitates. At and above 900 °C in the fully β range, columnar α-Zr(O) grains were observed. [ABSTRACT FROM AUTHOR]

Seven types of breakaway snares were evaluated for breaking strength and variability using a universal testing machine. Maximum tension before breakage for individual snares ranged from 142 to 486 pounds. Sheet metal locks which ripped out, and S-hooks which straightened, provided the least variable results. Coyotes (Canis latrans), mule deer (Odocoileus hemionus), domestic calves, and lambs were tested to determine the tension loads they applied to snares. Differences in tension toads among coyotes and nontarget species should allow for the development of snares that will consistently hold coyotes and release most larger nontarget animals.

Luminaire poles are commonly installed along highways to provide proper illumination in critical areas. When placing light poles in close proximity to guardrail, the poles may affect the guardrail's ability to safely contain and redirect vehicles. The interaction between a deflected guardrail system and a closely-positioned light pole may create unwanted stiffening or hinging of the barrier system around the pole. The pole may also present a snag hazard to impacting vehicles and induce vehicle instabilities. In this study, the barrier clearance distance, i.e. the lateral offset away from a breakaway light pole was investigated and evaluated. The minimum safe lateral offset away from the pole with respect to the Midwest Guardrail System (MGS) was determined to be 508 mm (20 in.) through crash testing and computer simulation with non-linear finite-element analysis. Two full-scale crash tests were conducted according to the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) impact safety criteria. In test no. ILT-1, a 2268-kg (5000-lb) pickup truck impacted the combination MGS with light pole system laterally offset 508 mm (20 in.) from back of posts at a speed of 100.7 km/h (62.6 mph) and an angle of 25.0°. In test no. ILT-1, the pickup truck was captured and safely redirected while impacting the light pole and disengaging the pole away from the base. In test no. ILT-2, a 1098-kg (2420-lb) small car impacted the combination MGS with light pole system laterally offset 508 mm (20 in.) from back of posts at a speed of 100.9 km/h (62.7 mph) and an angle of 25.6°. In test no. ILT-2, the car was safely contained and redirected while minimally contacting the light pole. The MGS with a lateral pole offset of 508 mm (20 in.) away from back of posts to front face of pole provided an acceptable safety performance to MASH TL-3 when critically impacted by a pickup truck and a small car. Thus, a minimum offset of 508 mm (20 in.) between the back of the MGS post and front face of the breakaway pole was sufficient to assure a safe performance of the MGS during vehicle impacts without undesired interaction with the pole. Accordingly, guidance for the safe pole placement behind the MGS was provided. [ABSTRACT FROM AUTHOR]

An external ultrathin α-Al2O3 scale grown on the Ni-base alloy 602 CA during air oxidation at 800 °C was characterized by means of high-resolution TEM/EDX and electron diffraction. Alloy samples pre-oxidized at 800 °C were subsequently exposed at 1100, 1150 and 1200 °C for up to 100 h. Whereas the external alumina remained stable at 1100 °C, with the increasing exposure temperature, the pre-grown alumina scale tended to break down resulting in an external chromia scale accompanied by internal alumina precipitation. The transition from external to internal Al oxidation was investigated using SEM/EDX/EBSD. The critical Al depletion at the scale-alloy interface during the post-exposure at 1100-1200 °C was modeled using the CALPHAD-based thermodynamic-kinetic approach. [ABSTRACT FROM AUTHOR]

The growth kinetics of the columnar oxide and α-Zr(O) layers on Zry-4 under mixed steam-air conditions at temperatures of 1273 and 1473 K were investigated in this study by means of post-test metallographic measurements. The hydrogen uptake was also determined by the hot extraction method. The kinetics of the columnar oxide layer obeyed a parabolic law for all air fractions at both temperatures. The parabolic oxidation rate constant of the columnar oxide increased with increasing air fraction, whereas the parabolic oxidation rate constant of α-Zr(O) layer seemed to be independent of the air fraction. At 1273 K, the kinetics was assessed until the separation of the columnar oxide from α-Zr(O). The columnar oxide lost its protectiveness after the separation. As a consequence of the separation, nitrides along with the porous oxide formed underneath the columnar oxide in higher extent. Nitrogen in the atmosphere was found to influence the origin of the separation and the formation of nitrides and the porous oxide considerably. Mixed steam-air conditions enhanced hydrogen absorption substantially. [ABSTRACT FROM AUTHOR]

Fundamental insights into the mechanism of breakaway oxidation in Fe9Cr1Mo steel are deduced, through advanced characterisation and modelling. Degradation at 600 °C/∼42 bar CO 2 for ∼20,000 h is emphasised: conditions relevant to components such as the finned superheater tubes used for advanced gas-cooled nuclear reactors. It is shown that such conditions are sufficient to cause carbon saturation of the metallic substrate, as confirmed by direct observation of extensive carbide precipitation but also numerical analysis of the carbon transport. Thus the observation of graphite precipitation close to the scale/metal interface is rationalised. Nonetheless, the activity of carbon at the scale/metal interface does not reach unity – with respect to graphite – at time zero. A modelling method is proposed which accounts for this kinetic retardation of the attack; this can be used to interpolate across the regimes within which breakaway oxidation is prevalent. It is a plausible model for extrapolation to the lower temperatures relevant to service conditions and is suitable for lifetime estimation – so-called ‘remnant life analysis’ – of such safety-critical components when prone to this form of attack. [ABSTRACT FROM AUTHOR]

The paper focuses on the phenomenon of breakaway occurring in high-temperature oxidation of zirconium. The oxidation kinetics were determined by thermogravimetric analysis of samples oxidized at 500 °C under synthetic air. The time associated with breakaway was identified and compared to results of an oxidation test coupled with an acoustic emission monitoring. Breakaway corresponded to the appearance of the first cracks in the zirconia scale and which generated an acoustic activity. A significant evolution of bursts energy and an increase in the number of hits allowed to class signals into three populations corresponding to the different steps of the oxidation kinetics. Postmortem observations for qualification of crack networks confirmed crack initiation at the oxide/metal interface at breakaway. A time offset was measured between first cracks occurring and their global effect on oxidation kinetics. [ABSTRACT FROM AUTHOR]

Water vapour and/or steam are well known to accelerate breakaway oxidation of chromia-forming alloys. Some authors have proposed that hydrogen promotes internal oxidation of chromium, resulting in breakaway oxidation. We tested this hypothesis by directly measuring oxygen permeability after oxidation in high p O 2 atmospheres containing water vapour. Palladium with 1 wt% chromium alloy was oxidized in dry and wet Ar-1%O 2 at 850 °C. The internal oxidation in all cases obeyed parabolic kinetics. The oxygen permeability deduced from Wagner's diffusion model showed small differences in the internal oxidation of the Pd-1Cr alloy in these gases. We conclude that hydrogen has no influence on oxygen permeability in chromium-containing alloys. [ABSTRACT FROM AUTHOR]

Exposure of high-temperature alloys to a low-P O2 oxidizing-sulfidizing environment above about 550 °C is often characterized by an initial period of protective oxidation followed by more rapid corrosion. This paper will provide a brief overview of alloy corrosion in oxidizing-sulfidizing atmospheres, with specific consideration given to the thermodynamic and kinetic aspects of the process, resulting modes of degradation, and alloy selection. The concept of a "critical microstructure" in the subsurface of the alloy as a prerequisite to initiating protective scale breakdown will also be discussed. The paper will conclude with a specific example of alloy development for the filtration of hot oxidizing-sulfidizing gases.

The PSI air oxidation model has been successfully implemented in the lump parameter code MELCOR. The PSI air oxidation model treats oxygen as an active species and nitrogen as a catalyst that accelerates the oxidation kinetics. The essential feature of the model is the transition from parabolic to linear kinetics. The implementation has been assessed against the previous post-test analyses for the air ingress experiment QUENCH-16 performed with a local version of RELAP5/SCDAPSim3.5. This version contains the PSI air oxidation model. The pre-oxidation and air phase were consistent when similar modelling options were used and all code versions were in fair agreement with the experimental data, showing consistency in the implementation of the model. The PSI air oxidation model will be used in the future for analysis of spent fuel pool uncovery sequences where steam/air mixture is the prototypical environment. [ABSTRACT FROM AUTHOR]

Scales grown on chromia forming alloys in CO2 are less protective than those developed during exposure to oxygen or air. Reaction with CO2 leads to faster chromia scale growth, the more rapid onset of breakaway and internal carburisation of the alloy. Conventional and laser Raman microscopy studies of Fe-Cr alloys show that local fluctuations in scale thickness are associated with varying degrees of chromium depletion. Local conversion of Cr2O3 to spinel leads to rapid outward iron diffusion and nucleation of Fe-rich oxide nodules. A TEM investigation reveals that reaction in CO2 produces finer grained Cr2O3, inward scale growth and more rapid scaling, as well as internal carburisation. Appropriate silicon additions to the alloys lead to the formation of a thin, glassy silica layer beneath the chromia, greatly slowed chromia thickening rates and the prevention of carburisation. Atom probe tomography is used to locate carbon within the chromia. [ABSTRACT FROM AUTHOR]

Scales grown on chromia forming alloys in CO2 are less protective than those developed during exposure to oxygen or air. Reaction with CO2 leads to faster chromia scale growth, the more rapid onset of breakaway and internal carburisation of the alloy. Conventional and laser Raman microscopy studies of Fe-Cr alloys show that local fluctuations in scale thickness are associated with varying degrees of chromium depletion. Local conversion of Cr2O3 to spinel leads to rapid outward iron diffusion and nucleation of Fe-rich oxide nodules. A TEM investigation reveals that reaction in CO2 produces finer grained Cr2O3, inward scale growth and more rapid scaling, as well as internal carburisation. Appropriate silicon additions to the alloys lead to the formation of a thin, glassy silica layer beneath the chromia, greatly slowed chromia thickening rates and the prevention of carburisation. Atom probe tomography is used to locate carbon within the chromia. [ABSTRACT FROM AUTHOR]

In this study, the frictional behavior of selected commercially available unfilled polymers, namely, polyether ether ketone, polytetrafluoroethylene, polyethylene terephthalate, and ultra-high molecular weight polyethylene against an Inconel shaft was investigated using a journal bearing test configuration in water-lubricated sliding contact. Dynamic friction curves were obtained for various shaft roughness values and polymer combinations. The results showed a significant influence of shaft surface roughness on running-in and steady state friction in water-lubricated conditions. Contact angle measurements revealed a significant increase in wettability of Inconel counterfaces. The X-ray photoelectron spectroscopy (XPS) analysis of the surfaces suggests formation of a reaction layer on worn Inconel surfaces when sliding against the polymers. The influences of counter surface roughness and load on frictional response of polymers were studied through intermittent tests by obtaining dynamic and breakaway friction maps for different polymer materials, shaft roughness values, and pressure combinations. In general, a trend of decreasing friction was obtained with increasing contact pressure; however, the materials’ frictional responses to variations in counter surface roughness were different. These results indicate that although a reduced counter surface roughness may be beneficial for dynamic friction of polymers in all lubrication regimes, it can adversely affect the materials’ breakaway friction response. [ABSTRACT FROM PUBLISHER]

Abstract: Using combined Raman spectroscopy, atomic force microscopy and optical microscopy, this paper suggests that breakaway oxidation of Zircaloy is caused by the change of circumferential stress sign from compressive to tensile, which triggers catastrophic cracks to propagate from the oxide free surface toward the oxide–metal interface. The stress sign changes at a critical oxide thickness, which depends on the circumferential stress at the interface. This biaxial interfacial stress is promoted by a lattice expansion stress that accompanies the tetragonal to monoclinic crystal phase transition. In contrast with current research in the literature, this allotropic transformation is suggested to be beneficial, not detrimental, because it contributes to retard the thresholds for the change of circumferential stress sign, and thus breakaway oxidation. The tetragonal phase was revealed to localize at the interface and adopt the shape of prismatic isosceles triangles detected at early stages of oxidation. These growth morphologies are consistent with a cationic oxidation mechanism. Upon phase transition, the monoclinic variant quickly dominates the oxide scale above the interfacial regions and forces the overall oxidation to proceed by an anionic diffusion mechanism. The results of Raman spectroscopy compared well with those of atomic force microscopy. [Copyright &y& Elsevier]

Abstract: A recently developed air oxidation model has been implemented in the code version SCDAPSim3.5 and used to analyse the air ingress experiments QUENCH-10 and QUENCH-16 as part of the model assessment. The experiments comprised pre-oxidation in steam, a period of air ingress, and reflood. The analysis focused on the thermal response and possible breakaway during the oxygen consumption. Of particular interest were the effect of the oxygen concentration on the kinetics and the effect of oxygen starvation on the oxidation excursion during the subsequent reflood. The large excursion observed in QUENCH-16 during reflood was not reproduced by the model; the possible causes were explored and indicated the need of further improvement in the model. [Copyright &y& Elsevier]

Abstract: A new model, primarily aimed at air oxidation has been recently developed at PSI, assessed against separate effects tests data and implemented into a developmental version of RELAP5/SCDAPSIM. Oxygen is treated as an active species and nitrogen as a catalyst that promotes breakaway, so that the essential feature of the model is the transition from parabolic to breakaway oxidation. As part of the second stage of the model assessment, analysis is performed of the air ingress bundle experiment PARAMETER-SF4 which comprised pre-oxidation in steam, a period of air ingress, and reflood. The analysis focuses on the thermal response and possible breakaway during, the oxygen consumption. Of particular interest is the effect of oxygen starvation on the oxidation excursion during the subsequent reflood. [Copyright &y& Elsevier]

Abstract: A tethered aerostat may break away due to the cable damage caused by abrasion or strong wind. In order to avoid losing the aerostat, the discharge valve will open automatically when the aerostat escapes into the air. It is necessary to know its breakaway characteristics because it is different from those of the launch process. This work develops the dynamic and thermal models for tethered aerostat breakaway characteristics with the finite difference method. Based on the developed models, a computer program in FORTRAN is developed. Then, the program is used to simulate tethered aerostat breakaway characteristics, including ascent and descent behaviors, flight altitude, flight duration, and the influence of the discharge valve characteristics, ascent velocity and hull volume on the hull overpressure. The simulation results are helpful for better understanding tethered aerostat breakaway characteristics and for developing tethered aerostat breakaway control strategies and systems. [Copyright &y& Elsevier]

Four elements of the long-enigmatic Heart Mountain detachment are the focus of this synthesis of new and earlier work. First, the geometry of the detachment system is more completely defined by our interpretation that the nearby South Fork thrust was the contractional toe of the Heart Mountain detachment during its early movement. Second, emplacement of the allochthon included phases with both catastrophic and slow rates of movement, driven by gravitational instability of active volcanoes above a dipping, pre-volcanic substrate. Third, initiation of displacement resulted from reduction of basal friction by elevated fluid pressure along the basal detachment, presumably beneath a critically stressed Coulomb wedge. Fourth, maintenance of low basal friction, to allow displacements of the allochthon in excess of 30 kilometers, was aided by endogenic formation of a gas suspension along the basal detachment. Thus, a unique combination of conditions and processes led to formation of the world's largest-known subaerial, detached extensional system. It represents a worst-case scenario for the magnitude of destruction resulting from sector collapse of an active subaerial volcano. [ABSTRACT FROM AUTHOR]

Background: Violence to mental health staff is a major problem in the UK. Breakaway training may improve knowledge, attitudes, and stress. It is unknown if breakaway training is effective in clinical environments.Aim: To audit the effectiveness of breakaway training in a sample of clinically-based mental health nurses in a medium secure forensic mental health unit.Method: Audit using a cross-sectional design with an opportunistic sample of 47 clinically-based mental health nursing staff in a forensic medium secure unit. Participants had previously been trained in breakaway techniques. They were approached by the audit team on the ward and randomly selected one of five possible life-threatening assaults that they then had to break away from. Measures were blind ratings by breakaway trainers of the participant's correct use of technique and time. Where participants were unable to break away after 10 seconds the scenario was stopped. Descriptive analysis of the sample and inter-rater agreement of breakaway trainers' ratings were conducted.Results: None of the sample had used a breakaway technique in the preceding 12 months; 40% (19/47) were unable to break away from a life-threatening assault within a 10-second period; 60% did not employ the correct breakaway technique.Conclusion: The effectiveness of breakaway training is questionable given that 40% of the sample were unable to break away from a life-threatening hold in time. Further replication is required. [ABSTRACT FROM AUTHOR]