Search

The potential of microbially induced carbonate precipitation (MICP) for soil bio-improvement has been widely studied as an alternative to the traditional cementation by Portland cement. While multiple-phase injection techniques are commonly used for MICP treatment, they impose complexities and require a high number of injections. One of the latest developments in biocementation research area is using one-phase-low-pH MICP method as a more effective and efficient alternative to the traditional two-phase method. However, the one-phase-low-pH method has its challenges. The main challenge is delaying the start of carbonate precipitation to produce a homogenous distribution of cementation in soil matrixes. This study has tried to expand the lag phase with magnesium substitution for 20% calcium cations and decrease the initial temperature of reagents. These actions prolonged the lag phase by about five times, improved the crystal structure of carbonate precipitation and enhanced the transportability of bacteria in a 1 m length sand column. A modified injection strategy for all-in-one solution was introduced, and its capabilities were investigated in long sand columns. This new injection strategy provided a more uniform urea conversion, carbonate precipitation, and strength. It also decreased the required bacteria by 75% and minimized the necessity of pH adjustment and the initial low temperature of reagents. [ABSTRACT FROM AUTHOR]

This article investigates the effectiveness of lottery incentive schemes for eliciting consumer valuations in large‐scale online experiments. We implement a fully incentivized condition within a geographically dispersed sample of consumers in which bids for a Criollo steak elicited by a Becker‐DeGroot‐Marschak mechanism are realized with certainty and the products are priority shipped in dry‐ice coolers. The fully incentivized condition is compared to between‐subject random incentivized schemes, in which only a fraction of subjects realize their choices. We tested two treatments with a 10% probability framed as a percentage or an absolute number of subjects, one treatment with a 1% probability, and a purely hypothetical reference condition. The results reveal that between‐subject random incentivized schemes with 10% and 1% payment probabilities are effective in eliciting valuations that are statistically indistinguishable from the fully incentivized scheme. In addition to finding insignificant statistical differences between 10% and 1% and the fully incentivized scheme, all incentivized conditions mitigate hypothetical bias, resulting in lower product valuations than the purely hypothetical condition. We contribute a novel methodological framework for conducting large‐scale experiments with geographically diverse and representative subjects, increasing the external validity and producing reliable valuations while significantly reducing financial and logistic constraints. [ABSTRACT FROM AUTHOR]

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents an experimental study of the seismic behavior of steel gravity frames with concrete on metal deck floor systems using multibay test specimens subjected to cyclic lateral loads. Fully bolted double-angle connections were used for the primary gravity connections under investigation. Key design variables and construction details under investigation include metal deck orientation, positioning of metal deck seams, and increased deck reinforcing ratios around the columns. Test specimens were simultaneously subjected to gravity loads and quasi-static displacement-controlled cyclic lateral loads. Results show that composite gravity connections exhibit substantial flexural stiffness, strength, and ductility, with some differences in response depending on connection design variables and construction details. Results from the system-level experiments using multibay test specimens demonstrate significant differences compared to previous subassembly tests, which indicates that the moment-resisting capacity of connections may potentially be underestimated in subassembly level tests. [ABSTRACT FROM AUTHOR]

The proliferation of web-connected devices has presentedsignificant opportunities and challenges to cognitive sci-ence — opportunities in that cognitive scientists can collectdata relevant to human cognition orders of magnitude fasterthan before, addressing questions that were otherwise impos-sible to address; and challenges in that cognitive scientistsrequire new infrastructure to collect these data and new meth-ods to analyze them once collected.This workshop brings together cognitive scientists who areat the forefront of these opportunities and challenges in scal-ing cognitive science, along with cognitive scientists whowould like to be, to engage in a day of interactive exchangeand development of ideas related to scaling cognitive science.The workshop is a full day. Each presentation addresses adifferent opportunity or challenge. One set of presentationshighlights opportunities. A second set highlights challengesof statistical analysis and data collection. In a break-out ses-sion, attendees address these opportunities and challengeshead on.

Local reinforcement corrosion damage reduces the load‐bearing capacity of reinforced concrete structures and, even more severely, their deformation capacity. This problem is of particular concern for cantilever retaining walls, whose loading is dominated by earth pressure and hence, depends on the wall deformations. With a limited deformation capacity at the ultimate limit state due to the locally corroded reinforcement, the earth pressure may not drop to its reduced value typically assumed in design, and simultaneously, the structural resistance may be severely impaired by the cross‐section loss. Load redistributions are impeded since retaining walls are statically determined vertically and typically segmented longitudinally. This increases the risk that affected structures collapse, exhibiting a brittle failure. The situation is aggravated by the fact that the wall deformations prior to failure are too small to be detected by conventional monitoring, as indicated by a previous study. To improve the basis for quantifying the related risks and the magnitude of prefailure deflections, this study investigates the load‐deformation behavior of cantilever retaining walls affected by local pitting corrosion, focusing on (i) the influence of the corrosion pit distribution among different reinforcing bars on the load‐bearing and deformation capacity and (ii) the interdependence of corrosion, reduced deformation capacity and deformation‐dependent loading. To this end, eight large‐scale experiments on retaining wall segments were conducted in the Large Universal Shell Element Tester (LUSET), simulating the lower part of a 4.65‐m‐tall cantilever retaining wall. Five specimens contained initial damage (pitting corrosion simulated by a spherical mill). In the remaining three specimens, artificial corrosion damage was induced during the experiments. For two of the latter specimens, the loading was adapted in real‐time control depending on their deformation to simulate the decreasing earth pressure. These are the first large‐scale hybrid tests in the field of corrosion research to our knowledge. The experiments confirmed that the ultimate load and the corresponding deformation strongly differ depending on the corrosion pit distribution, even among specimens with equal mean cross‐section loss. Furthermore, it was found that the deformation increase due to corrosion damage depends on the loading and, hence, on the compaction of the backfill. The observed deformation increase ranged between 0.8 and 1.4 mm per meter height at 40% cross‐section loss, with loose soil causing a larger deformation increase. The load transfer between the damaged and undamaged reinforcing bars was found to take place in the first two crack elements above the construction joint. Local bending moments occurred in the reinforcing bars in the vicinity of the corrosion pits due to the shift of the center of gravity of the bar at the pit. Fiber optic strain sensing allowed visualizing the bending moment decrease in the embedded part of the damaged bars as a consequence of a lateral bearing pressure. [ABSTRACT FROM AUTHOR]

This study investigates the behaviour and failure mechanisms of beam-to-column dowel connections in precast industrial halls under lateral loads. Two large-scale cyclic tests were performed to evaluate the assembly failure and its relationship with the dowel connection. The results demonstrated that the assembly failure coincided with the dowel connection failure, governed by dowel yielding and concrete spalling of the column fork. No significant damage was observed in the concrete elements outside the connection area. The dissipative failure mechanism of the column was not achieved, indicating that this dowel connection is not capable to transmit sufficient lateral load. The maximum capacity of the dowel connection was influenced by the concrete coverage of the dowel in relation to the side of the column fork. This research serves as a basis for further investigation and potential improvements in the design and performance of connections in precast concrete structures.

The scaling-effect of mixture explosion is an unresolved issue in explosion science. In this work, we carry out experimental measurements of explosion characteristics using hydrogen/methane/air (H 2 /CH 4 /air) mixtures in two tubes with lengths of 1.5 m and 60 m. The explosion overpressure of the mixtures increases exponentially with hydrogen mole fractions in the small tube, as expected. In contrast, explosion overpressure increases rapidly, causing detonation when hydrogen is added to the mixtures. Comparing measurements in both tubes, the explosion overpressure exhibits a clear scaling-effect dependence on the tube size. The scaling-effect cannot be explained by the aspect ratio (AR) of the tube. The analysis of the hotspot size, which is correlated with the ignition delay time of mixtures, is the critical factor governing the scaling-effect of explosion seen in a large tube. • A scaling-effect of explosion in H 2 /CH 4 /air mixtures exists in a 60 m tube. • Explosion overpressure increases rapidly when hydrogen is added. • The scaling-effect cannot be explained by the aspect ratio. • Ignition delay time plays an important role in the scaling-effect of explosion. • Scaling-effect of explosion is governed by the hotspot size. [ABSTRACT FROM AUTHOR]

This paper proposes a novel embedded column base (ECB) connection that defies the current paradigm in capacity-designed steel moment-resisting frames (MRFs) where column bases have been traditionally considered as nondissipative. In the proposed concept, a dissipative zone is introduced as part of the embedded portion of the steel column. This zone features a reduced cross section and is decoupled from the concrete footing with a debonding material layer. The surrounding concrete effectively restrains the embedded section against nonlinear geometric instabilities, thereby retaining simplicity in the design process. Large-scale experiments suggest that, contrary to its conventional counterpart, the proposed dissipative ECB connection exhibits a stable hysteretic response until large lateral drift demands (i.e., 7% rad). It is also demonstrated that the dissipative ECB connection is resilient to local buckling-induced axial shortening, such that it lowers the repairability needs of slender wide-flange steel columns after earthquakes. Column twisting is also minimized throughout the loading history. The results indicate that both the elastic stiffness and flexural yield strength of the proposed ECB connection can be analytically derived for potential use in engineering design. It is found that a simple nondegrading bilinear model suffices to describe the hysteretic response of the proposed ECBs for performance-based assessment of steel MRFs. [ABSTRACT FROM AUTHOR]

This study investigates the behaviour and failure mechanisms of beam-to-column dowel connections in precast industrial halls under lateral loads. Two large-scale cyclic tests were performed to evaluate the assembly failure and its relationship with the dowel connection. The results demonstrated that the assembly failure coincided with the dowel connection failure, governed by dowel yielding and concrete spalling of the column fork. No significant damage was observed in the concrete elements outside the connection area. The dissipative failure mechanism of the column was not achieved, indicating that this dowel connection is not capable to transmit sufficient lateral load. The maximum capacity of the dowel connection was influenced by the concrete coverage of the dowel in relation to the side of the column fork. This research serves as a basis for further investigation and potential improvements in the design and performance of connections in precast concrete structures. [ABSTRACT FROM AUTHOR]

Aim: Marine and freshwater ecosystems are increasingly threatened by human activities. For over a century, scientists have been testing many biological, chemical and physical questions to understand various ecosystems and their resilience to different stressors. While the majority of experiments were conducted at small‐scale laboratory settings, lately large mesocosm experiments have become more and more common. Yet, it still remains unclear how the scale (i.e. space) and ecological complexity (i.e. community versus limited number of species) of experiments affect the results and to what extent different experimental types are comparable. Innovation: Here, we conducted two types of experiments, run at different scale and ecological‐complexity levels (i.e. outdoor large‐scale community‐level mesocosm versus indoor small‐scale two‐species laboratory experiment), to assess the effects of marine heatwaves on two gammarid species. Main Conclusions: Our approach detected differences in abundance and relative population growth between the two experimental types for one out of the two tested species, but no difference in heatwave impacts on any of the species, independently of which experimental type was used. The larger space in the mesocosm, accompanied with inclusion of the community, benefited this species, demonstrating stronger performance in the mesocosm than in the laboratory experiment. Though, our study design cannot directly distinguish if scale or ecological complexity of the experiments, or both, caused the observed discrepancy in our findings. Furthermore, inconsistency in results among laboratory experiments complicates the extrapolations and generalization of the laboratory results. Yet, our findings indicate the importance of space, density‐dependent effects, biotic interactions and complexity of natural environments in buffering, or boosting, the direct effects of environmental stress on organisms. Therefore, we urge the use of large‐scale community‐level mesocosm experiments instead of small‐scale single‐species laboratory ones whenever possible, and emphasize a necessity of great caution when interpreting the results of laboratory experiments. [ABSTRACT FROM AUTHOR]

The Pressure Peaking Phenomena (PPP) is the effect of introducing a light gas into a vented volume of denser gas. This will result in a nonequilibrium pressure as the light gas pushes the dense gas out at the vent. Large scale experiments have been performed to produce relevant evidence. The results were used to validate an analytical model. Pressure and temperature were measured inside a constant volume, while the mass flow and vent area were varied. The analytical model was based on the conservation of mass and energy. The results showed that increasing the mass flow rate, the peak pressure increases and with increasing the ventilation area, the peak pressure decreases. Peak pressure was measured above 45 kPa. Longer combustion time resulted in higher temperatures, increasing an underpressure effect. The experimental results showed agreement with the analytical model results. The model predicts the pressures within reasonable limits of+/-2 kPa. The pressure peaking phenomena could be very relevant for hydrogen applications in enclosures with limited ventilation. This could include car garages, ship hull compartments as well as compressor shielding. This work shows that the effect can be modeled and results can be used in design to reduce the consequences. • Large scale experimental pressure peaking phenomena. • Constant volume with pressure and temperature measurements. • Peak pressure was measured above 45 kPa. • Model predicts the pressures within+/-2 kPa. • Increasing the m ˙ i n , H 2 - increase p p e a k , increasing A v e n t - decreases p p e a k . [ABSTRACT FROM AUTHOR]

The NHERI Lehigh Experimental Facility, as part of the NSF-funded Natural Hazards Engineering Research Infrastructure (NHERI) program, was established in 2016 as an open-access facility. This facility enables researchers to conduct state-of-art research on natural hazard mitigation in civil infrastructure systems, including high-performance numerical and physical testing to improve the resilience and sustainability of the civil infrastructure against natural hazards. The facility has the unique ability to conduct real-time multi-directional hybrid simulation (RTHS) on large-scale structural systems using 3D non-linear numerical models combined with large-scale physical models of structural and non-structural components. The Lehigh Experimental Facility possesses testbeds that include a lateral load-resisting system characterization testbed, a non-structural component multi-directional dynamic loading simulator, full-scale and reduced-scale damper testbeds, a tsunami and storm surge debris impact force testbed, and a soil-foundation structure interaction testbed. This paper describes the infrastructure and capabilities of the NHERI Lehigh Experimental Facility. Developments by the facility in advancing large-scale RTHS are detailed. Examples of research projects performed by users of the facility are then provided, including large-scale RTHS of steel frame buildings with magneto-rheological (MR) dampers and non-linear viscous dampers subject to strong earthquake ground motions; 3D multi-hazard large-scale RTHS of tall steel buildings subject to multi-directional wind and earthquake ground motions; characterization of a novel semi-active friction device based on band brake technology; and testing of cross-laminated timber self-centering coupled wall-floor diaphragm-gravity systems involving multi-directional loading.

The aim of this study was to validate a model for predicting overpressure arising from accidental hydrogen releases in areas with limited ventilation. Experiments were performed in a large-scale setup that included a steel-reinforced container of volume 14.9 m3 and variable ventilation areas and mass flow rates. The pressure peaking phenomenon, characterized as transient overpressure with a characteristic peak in a vented enclosure, was observed during all the experiments. The model description presented the relationship between the ventilation area, mass flow rate, enclosure volume, and discharge coefficient. The experimental results were compared with two prediction models representing a perfect mix and the real mix. The perfect mix assumed that all the released hydrogen was well stirred inside the enclosure during the releases. The real mix prediction s used the hydrogen concentration and temperature data measured during experiments. The prediction results with both perfect mix and real mix showed possible hazards during unignited hydrogen releases. • Hydrogen releases inside an enclosure confirme PPP. • Description of large-scale experimental setup and instrumentation. • Overpressures as a consequences of vent size configuration and mass flow rates. • The model for the unignited hydrogen releases is validated against 10 experiments. • Two models using either real mix and perfect mix are investigated. [ABSTRACT FROM AUTHOR]

Web shell is a malicious script file that can harm web servers. Web shell is often used by intruders to perform a series of malicious operations on website servers, such as privilege escalation and sensitive information leakage. Existing web shell detection methods have some shortcomings, such as viewing a single network traffic behavior, using simple signature comparisons, and adopting easily bypassed regex matches. In view of the above deficiencies, a web shell detection method based on multiview feature fusion is proposed based on the PHP language web shell. Firstly, lexical features, syntactic features, and abstract features that can effectively represent the internal meaning of web shells from multiple levels are integrated and extracted. Secondly, the Fisher score is utilized to rank and filter the most representative features, according to the importance of each feature. Finally, an optimized support vector machine (SVM) is used to establish a model that can effectively distinguish between web shell and normal script. In large-scale experiments, the final classification accuracy of the model on 1056 web shells and 1056 benign web scripts reached 92.18%. The results also surpassed well-known web shell detection tools such as VirusTotal, ClamAV, LOKI, and CloudWalker, as well as the state-of-the-art web shell detectionmethods. [ABSTRACT FROM AUTHOR]

Knowledge of the first principles defining fire behaviour in large enclosures remains limited despite their common use in modern tall buildings. The evolution of a fire in large enclosures can be defined by the relationship between the flame front and burnout velocities (V S / V BO). This relationship can be classified into three distinct fire spread modes being Mode 1 (V S / V BO → ∞), Mode 2 (V S / V BO > 1), and Mode 3 (V S / V BO ≈ 1). The mechanisms governing flame spread and burnout are investigated using four full-scale enclosure fire experiments with high porosity wood cribs with similar enclosure geometries. Flame and burnout front positions and velocities are estimated using video data. Velocities are affected by the heat feedback from the enclosure and smoke layer to the fuel. The spread velocity shows two regimes, a minimum external heat flux above which there is surface spread (q ˙ s , min ″) and a heat flux that defines the onset of very rapid flame spread (q ˙ rs , crit ″). A phenomenological model is developed to help identify the underlying mechanisms controlling the transition between the different spread modes. Both the model and data show that for wood cribs, the dependence of the burnout front velocity to the external radiation is weak, whereas the dependence of the flame spread velocity to the external and flame heat flux is strong. A transition from Mode 3 (V S / V BO ≈ 1) to Mode 2 (V S / V BO > 1) occurs with increasing external heat fluxes above q ˙ s , min ″. The transition to Mode 1 (V S / V BO → ∞) is further defined once q ˙ rs , crit ″ is attained due to a sudden increase in the flame heat flux by changing the ventilation condition, or by significant increases in the external heat flux from the enclosure. [ABSTRACT FROM AUTHOR]

This paper presents a series of experiments on the effectiveness of existing mechanical ventilation systems during accidental hydrogen releases in confined spaces, such as underground garages. The purpose was to find the mass flow rate limit, hence the TPRD diameter limit, that will not require a change in the ventilation system. The experiments were performed in a 40 ft ISO container in Norway, and hydrogen gas was used in all experiments. The forced ventilation system was installed with a standard 315 mm diameter outlet. The ventilation parameters during the investigation were British Standard with 10 ACH and British Standard with 6 ACH. The hydrogen releases were obtained through 0.5 mm and 1 mm nozzles from different hydrogen reservoir pressures. Both types of mass flow, constant and blowdown, were included in the experimental matrix. The analysis of the hydrogen concentration of the created hydrogen cloud in the container shows the influence of the forced ventilation on hydrogen releases, together with TPRD diameter and reservoir pressure. The generated experimental data will be used to validate a CFD model in the next step.

It is expected that the IEEE 802.15.4e-TSCH designed for wireless industrial sensor networks will be used in IoT systems. This standard relies on techniques such as channel hopping and bandwidth reservation to ensure both energy savings and reliable transmissions. Since many applications may require low end-to-end delay (e.g., alarms), we propose here a distributed algorithm to schedule the transmissions while upper bounding the end-to-end source-sink delay. Our strategy constructs stratums, regrouping all the nodes with the same depth in the DODAG Destination Oriented Directed Acyclic Graph constructed by RPL. Then, different time-frequency blocks(bands) are assigned deterministically to each stratum. By appropriately tuning the size of each block and chronologically organizing them, we are able to guarantee any packet is delivered along the path length to the border router before the end of the slotframe. We also provide self-healing mechanism to detect and alleviate local collisions. Experiments on a large-scale testbed prove the relevance of this approach to reduce the end-to-end delay while minimizing the number of collisions, prejudicial to the reliability in multihop networks. [ABSTRACT FROM AUTHOR]

Abstract This paper describes the design, construction principles and operations of the distillation and stripping pilot plants tested at the Daya Bay Neutrino Laboratory, with the perspective to adapt these processes, system cleanliness and leak-tightness standards to the final full scale plants to be used for the purification of the liquid scintillator of the JUNO neutrino detector. The main goal of these plants is to remove radio impurities from the liquid scintillator while increasing its optical attenuation length. Purification of liquid scintillator will be performed with a system combining alumina oxide, distillation, water extraction and steam (or N 2 gas) stripping. Such a combined system will aim at obtaining a total attenuation length greater than 20 m @430 nm, and a bulk radiopurity for 238U and 232Th in the 10−15 ÷ 10−17 g/g range. The pilot plants commissioning and operation have also provided valuable information on the degree of reliability of their main components, which will be particularly useful for the design of the final full scale purification equipment for the JUNO liquid scintillator. This paper describes two of the five pilot plants since the Alumina Column, fluorescent material mixing and the Water Extraction plants are being developed by the Chinese part of the collaboration. [ABSTRACT FROM AUTHOR]

Web shell is a malicious script file that can harm web servers. Web shell is often used by intruders to perform a series of malicious operations on website servers, such as privilege escalation and sensitive information leakage. Existing web shell detection methods have some shortcomings, such as viewing a single network traffic behavior, using simple signature comparisons, and adopting easily bypassed regex matches. In view of the above deficiencies, a web shell detection method based on multiview feature fusion is proposed based on the PHP language web shell. Firstly, lexical features, syntactic features, and abstract features that can effectively represent the internal meaning of web shells from multiple levels are integrated and extracted. Secondly, the Fisher score is utilized to rank and filter the most representative features, according to the importance of each feature. Finally, an optimized support vector machine (SVM) is used to establish a model that can effectively distinguish between web shell and normal script. In large-scale experiments, the final classification accuracy of the model on 1056 web shells and 1056 benign web scripts reached 92.18%. The results also surpassed well-known web shell detection tools such as VirusTotal, ClamAV, LOKI, and CloudWalker, as well as the state-of-the-art web shell detectionmethods.

The accident at Japan's Fukushima Daiichi nuclear power plant in March 2011, caused by an earthquake and a subsequent tsunami, resulted in a failure of the power systems that are needed to cool the reactors at the plant. The accident progression in the absence of heat removal systems caused Units 1-3 to undergo fuel melting. Containment pressurization and hydrogen explosions ultimately resulted in the escape of radioactivity from reactor containments into the atmosphere and ocean. Problems in containment venting operation, leakage from primary containment boundary to the reactor building, improper functioning of standby gas treatment system (SGTS), unmitigated hydrogen accumulation in the reactor building were identified as some of the reasons those added-up in the severity of the accident. The Fukushima accident not only initiated worldwide demand for installation of adequate control and mitigation measures to minimize the potential source term to the environment but also advocated assessment of the existing mitigation systems performance behavior under a wide range of postulated accident scenarios. The uncertainty in estimating the released fraction of the radionuclides due to the Fukushima accident also underlined the need for comprehensive understanding of fission product behavior as a function of the thermal hydraulic conditions and the type of gaseous, aqueous, and solid materials available for interaction, e.g., gas components, decontamination paint, aerosols, and water pools. In the light of the Fukushima accident, additional experimental needs identified for hydrogen and fission product issues need to be investigated in an integrated and optimized way. Additionally, as more and more passive safety systems, such as passive autocatalytic recombiners and filtered containment venting systems are being retrofitted in current reactors and also planned for future reactors, identified hydrogen and fission product issues will need to be coupled with the operation of passive safety systems in phenomena oriented and coupled effects experiments. In the present paper, potential hydrogen and fission product issues raised by the Fukushima accident are discussed. The discussion focuses on hydrogen and fission product behavior inside nuclear power plant containments under severe accident conditions. The relevant experimental investigations conducted in the technical scale containment THAI (thermal hydraulics, hydrogen, aerosols, and iodine) test facility (9.2 m high, 3.2 m in diameter, and 60 m3 volume) are discussed in the light of the Fukushima accident.

The evolution of different initial beach profiles towards the same final beach configuration is investigated based on large-scale experimental data. The same wave condition was performed three times, each time starting from a different initial profile morphology. The three different initial profiles are an intermediate energy profile with an offshore bar and a small swash berm, a plane profile and a low energy profile with a large berm. The three cases evolve towards the same final (equilibrium) profile determined by the same wave condition. This implies that the same wave condition generates different sediment transport patterns. Largest beach changes and differences in hydrodynamics occur in the beginning of the experimental cases, highlighting the coupling between morphology and hydrodynamics for beach evolution towards the same profile. The coupling between morphology and hydrodynamics that leads to the same final beach profile is associated with differences in sediment transport in the surf and swash zone, and is explained by the presence of bar and berm features. A large breaker bar and concave profile promote wave energy dissipation and reduce the magnitudes of the mean near-bed flow velocity close to the shoreline limiting shoreline erosion. In contrast, a beach profile with reflective features, such as a large berm and a small or no bar, increases negative velocity magnitudes at the berm toe promoting shoreline retreat. The findings are summarised in a conceptual model that describes how the beach changes towards equilibrium from two different initial morphologies.

This paper presents the results of two large-scale tests performed to clarify the conditions for the detonation of propane-air compositions in model surface clouds in the absence and in the presence of confining rigid walls. Model clouds with dimensions of 15 × 6 × 4.2 and 15 × 6 × 2 m were confined by plastic tents. A mixture of the starting reagents in the cloud was ignited by hot detonation products propagating along a perforated ø0.82 × 23 m tube passing through the space of the tent. Hot detonation products were injected from the tube through holes of 20 and 40 mm diameters. Detonation of the propane-air mixture in the tube was initiated by explosion of an explosive charge placed at the tube end. Detonation occurred in the propane-air cloud bounded on one side by a rigid vertical wall, and no detonation was observed in the cloud with similar injection of hot products without a rigid wall. It is concluded that the divergence or convergence of the flows of hot detonation products plays a key role in the process, being responsible for the presence or absence of detonation, respectively, in the mixing region. [ABSTRACT FROM AUTHOR]

The performance of segmental pipelines under large ground deformation is strongly influenced by the axial pullout and compressive load capacity of their joints, as well as by the limits on joint rotation during permanent and transient ground deformation. Although ductile iron (DI) pipelines with push-on joints are commonly used in water distribution systems, experimental data and numerical simulation related to their performance under large ground movements are lacking. This paper reports on a series of specially designed four-point bending experiments and finite-element (FE) simulations to characterize 150-mm (6-in.) diameter DI push-on joints. The results were used to develop a relationship between rotation and metal binding as a function of axial pullout, as well as to determine the magnitudes of rotation and moment that initiate joint leakage. FE simulations were performed to investigate the deformation associated with joint leakage. Uniaxial tension and one-dimensional compression tests were performed on the elastomeric gasket and fitted with hyperelastic strain energy approximations to characterize behavior under extreme loading. Numerical models demonstrate joint leakage to be independent of load path, and that a unique pressure boundary predicts leakage for many combinations of deformation. [ABSTRACT FROM AUTHOR]

Structural engineers are engaged in the development, design, construction and maintenance of new generation smart structures that are capable of withstanding multiple catastrophic events such as earthquakes, fire and tsunamis. Accordingly, the prediction of structural performance from initial linear-elastic behaviour to collapse is essential to assess the effectiveness of new design methods and the implementation of new retrofitting strategies. Although there has been much advancement in numerical methods, experimental observations remain critical for better understanding and predicting a structure’s response. The Multi-Axis Substructure Testing (MAST) system has been developed to expand the capabilities of experimental testing for three-dimensional simulation of extreme loads on critical components of large and complex structural systems. The MAST system uses eight high-capacity hydraulic actuators and a sophisticated 6-DOF mixed-mode control system that enables simultaneous application of multi-directional continuously varying states of deformation or load to structural components. An overview of the MAST facility and its components, the actuator assemblies and the details of 6-DOF control system are presented in this paper. Three experiments including quasi-static cyclic, local and distributed hybrid simulation tests were conducted on a seismically excited concrete structure to validate the performance of the MAST system in mixed-mode control by imposing simultaneously the axial load in force control and lateral deformations in displacement control. [ABSTRACT FROM AUTHOR]

Electrocoagulation (EC) treatment of 100 mg/L synthetic wastewater (SWW) containing humic acids was optimized (achieving 90% COD Mn and 80% DOC removal efficiencies), after which real peat bog drainage waters (PBDWs) from three northern Finnish peat bogs were also treated. High pollutant removal efficiencies were achieved: P tot , TS, and color could be removed completely, while N tot , COD Mn , and DOC/TOC removal efficiencies were in the range of 33–41%, 75–90%, and 62–75%, respectively. Al and Fe performed similarly as the anode material. Large scale experiments (1 m 3 ) using cold (T = 10–11 °C) PBDWs were also conducted successfully, with optimal treatment times of 60–120 min (applying current densities of 60–75 A/m 2 ). Residual values of Al and Fe (complete removal) were lower than their initial values in the EC-treated PBDWs. Electricity consumption and operational costs in optimum conditions were found to be low and similar for all the waters studied: 0.94 kWh/m 3 and 0.15 €/m 3 for SWW and 0.35–0.70 kWh/m 3 and 0.06–0.12 €/m 3 for the PBDWs (large-scale). Thus, e.g. solar cells could be considered as a power source for this EC application. In conclusion, EC treatment of PBDW containing humic substances was shown to be feasible. [ABSTRACT FROM AUTHOR]

This article examines gender differences in an experimental trust game. Recent studies have shown that men trust more and that women are more reciprocal in laboratory experiments. Participants in these studies, however, are typically university students who may not be representative of the entire population. In this study, we use data from a large-scale experiment with heterogeneous subjects who are representative of the German population. We find that men exhibit not only more trusting behaviour, but also more reciprocating behaviour than women. Moreover, our results are indicative of age-dependent gender differences. For men, we find an inverse U-shaped relationship between age, on the one hand, and both trust and reciprocity, on the other; however, we do not find age effects for women. [ABSTRACT FROM PUBLISHER]

Data are used from three relatively large-scale experimental soil-foundation-superstructure interaction (SFSI) systems to develop reduced-order computational models for response prediction and change-detection relevant to structural health monitoring and computational mechanics. The three systems under consideration consist of identical superstructures with: (i) fixed base; (ii) box foundation; and (iii) pile foundation. The three SFSI systems were developed and experimentally tested at Tongji University. In the first part of the study, a computational time-marching prediction framework is proposed by incorporating trained neural network(s) within an ordinary differential equation solver and dynamically predicting the response (i.e., displacement and velocity) of the SFSI systems to various earthquake excitations. Two approaches are investigated: global approach and subsystem approach. Both approaches are tested and validated with linear and nonlinear systems, and their respective pros and cons are discussed. In the second part of the study, the trained neural networks from the global approach are further used for change-detection in the SFSI systems. The detected changes in the systems are then quantified through a measure of a normalized error index. Challenges related to the physical interpretation of the quantified changes in the SFSI systems are addressed and discussed. It is shown that the general procedures adopted in this paper provide a robust nonlinear model that is reliable for computational studies, as well as furnishing a robust tool for detecting and quantifying inherent change in the system. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Landslide dams form when landslide materials reach rivers causing complete or partial blockage. It is known that overtopping water flows and seepage flows are two crucial processes that induce dam failure. In several instances, the landslide dams collapse is caused by the coupled influence of seepage flows and overtopping water. This study aims to evaluate the contribution of seepage flows to the overtopping failure of landslide dams in terms of dam stability, breach duration, and flow discharge. We conducted two field experiment tests to simulate landslide dam failure modes: overtopping failure and overtopping-seepage coupling. Results show that the internal erosion due to seepage induces the loss of fine particles, resulting in a fourfold increase in dam deformation relative to when seepage is minimal. In the case overtopping and seepage failure, the outburst duration is shortened by two-thirds, but the peak outburst discharge is increased by nearly two times compared with the pure overtopping failure. Sediments accumulate at the downstream channel for overtopping failure, but erosion is observed before accumulation when the "overtopping and seepage" failure occurs. Fine grain sizes are limited to the downstream bed for both failure modes, which indicates the equal mobility of sediments involved in the outburst flood from a landslide dam breach. • Seepage flow leads to the loss of fine particles and irreversible dam deformation. • The "overtopping and seepage" failure mode significantly influence the outburst duration and discharge. • The outburst flood of landslide dams inhibit grain size fining at the downstream bed. • The extent of seepage erosion determines the failure models. [ABSTRACT FROM AUTHOR]

SUMMARY The self-centering rocking steel frame is a seismic force resisting system in which a gap is allowed to form between a concentrically braced steel frame and the foundation. Downward vertical force applied to the rocking frame by post-tensioning acts to close the uplifting gap and thus produces a restoring force. A key feature of the system is replaceable energy-dissipating devices that act as structural fuses by producing high initial system stiffness and then yielding to dissipate energy from the input loading and protect the remaining portions of the structure from damage. In this research, a series of large-scale hybrid simulation tests were performed to investigate the seismic performance of the self-centering rocking steel frame and in particular, the ability of the controlled rocking system to self-center the entire building. The hybrid simulation experiments were conducted in conjunction with computational modules, one that simulated the destabilizing P-Δ effect and another module that simulated the hysteretic behavior of the rest of the building including simple composite steel/concrete shear beam-to-column connections and partition walls. These tests complement a series of quasi-static cyclic and dynamic shake table tests that have been conducted on this system in prior work. The hybrid simulation tests validated the expected seismic performance as the system was subjected to ground motions in excess of the maximum considered earthquake, produced virtually no residual drift after every ground motion, did not produce inelasticity in the steel frame or post-tensioning, and concentrated the inelasticity in fuse elements that were easily replaced. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Maar–diatreme eruptions are hazardous to people and infrastructure, and are also linked to the formation of the kimberlitic variety of diatremes, which is important economically. Processes occurring in the subsurface diatreme and their relation to surface eruptions are not yet well understood. We conducted field-scale experiments using analog materials to shed more light on these processes, especially the formation of the proto-diatreme during the first explosions of a maar eruption. Specifically, a series of buried explosions in a prepared, layered substrate (pad) produced craters, extra-crater deposits and sub-crater deposits analogous to volcanic maar craters, tephra rings and incipient diatremes. Post-explosion substrate excavation revealed that single large explosions produce sub-crater deposits extending nearly to the crater-rim crest. The same energy divided into three blasts, either co-located or at different depths with the same epicenter, produced narrower and sometimes deeper sub-crater deposits even though the final sizes of the craters were similar to that produced by the single large blast. The sub-crater deposits have an upper zone with domains from different substrate depths, and an underlying zone distinguished primarily by being more loosely packed than the original substrate. Videos show surface motion extending beyond the post-shot crater rim, and largely vertical ejection and fallback of material into the footprint of these deposits, especially for the explosions that occurred below optimal depth of burial. We infer that much of the loosely packed material was disassembled, vertically transported to different heights during the explosions, then fell back without significant relative lateral movement of grains. However, subvertical fallback did produce apparent cross-cutting structures in shallow sub-crater deposits. One explosion ejected material from the deepest substrate horizon, but it was redeposited only within the crater and is unrepresented in the ejecta rim. Implications of the experiments for maar–diatreme volcanoes, including some kimberlite pipes, are as follows: (1) vertical focusing of deep explosions in the diatreme explains the deficit of deep wallrock lithics observed at maar volcanoes; (2) direct vertical fallback is possibly an important process forming diatreme deposits, especially during the earliest stages; and (3) even in our limited simulation the number and scaled depth of explosions clearly affect proto-diatreme size and structure. [Copyright &y& Elsevier]

Abstract: The eruptive columns of explosive volcanism are fed by a gas–particle conduit flow, which characteristics determine the eruptive regime and are important for assessing the hazard of active volcanoes. In this paper, by means of the combined use of large-scale experiments and numerical modeling, a study on some parameters of the gas–particle conduit flow of explosive eruptions is carried out. A 1D two-phase non-homogeneous Eulerian–Eulerian model has been developed for checking the influence of some crucial quantities: interphase drag, particle–wall friction and particle shape factor. Hundreds of different parameters combinations are tested and used for the simulation of controlled experimental runs. The parameter combination that best fits the whole set of experiments, including both column collapses and convective plumes, results into an average error of about 10%. A further analysis has been carried out to determine the sensitivity of solutions to model parameters. The choice of the interphase drag does not influence dramatically the solution, except for highly concentrated flows. The particle shape factor severely affects gas and particle velocities. The influence of various particle–wall friction laws, which were originally obtained in pneumatic engineering, is thoroughly investigated, as the suitability of these laws has never been proved in volcanology. A detailed parametric analysis allowed the re-calibration of two of these laws, which are now specifically tailored for the case of highly concentrated conduit flows that feed collapsing columns, and dilute flows that feed convective plumes. [Copyright &y& Elsevier]