Performance study of large-area glass resistive plate chambers with different spacer configurations

Optimization of spacer and gas distribution inside the glass resistive plate chamber (RPC) is reported. Simulation studies demonstrate improvements on the gas flow velocity homogeneity and lower vorticity inside the gas chamber. The optimized spacer configuration (76 spacers) decreases the number of spacers by 24% compared to the original design (100 spacers), thus helps significantly reduce the non-active or low-efficiency area caused by spacers while maintaining similar deformation uniformity of the electrodes. Large area glass RPCs with 1×1 m^2 size using two types of spacer configurations are constructed and tested with cosmic muons events. The muon detection efficiencies for RPCs are greater than 95%.

DEM-FDM Coupled Numerical Study on the Reinforcement of Biaxial and Triaxial Geogrid Using Pullout Test

The key to modeling the interlocking of geogrid-reinforced ballast is considering both the continuous deformation characteristics of the geogrid and the discontinuity of the ballast particles. For this purpose, pullout tests using biaxial and triaxial geogrids were simulated using the coupled discrete element method (DEM) and finite difference method (FDM). In this coupled model, two real-shaped geogrid models with square and triangular apertures were established using the solid element in FLAC3D. Meanwhile, simplified shaped clumps were used to represent the ballast using PFC3D. The calibration test simulation showed that the accurately formed geogrid model can reproduce the deformation and strength characteristics of a geogrid. The pullout simulation results show that the DEM-FDM method can well predict the relationship between pullout force and displacement, which is more accurate than the DEM method. For ballast particles of 40 mm in size, both the experiment and simulation results showed that the triaxial geogrid of 75 mm is better than the 65-mm biaxial geogrid . In addition, the DEM-FDM method can study the interaction mechanism between the particles and the geogrid from a microscopic view, and also reveal the similar deformation behavior of the geogrid in the pullout process. Therefore, the DEM-FDM coupled method can not only investigate the interlocking mechanism between the ballast and particles but can also provide a great method for evaluating the performance of different types of geogrids.

Scale dependency of segmentation along the strike of normal faults.

<p>The present study provides insights on the segmented nature of normal faults as a function of scale, and attempts to identify whether segmentation is scale invariant, scale dependent or hierarchical. This is a topic of critical importance for studies of fault development and in modelling exercises where one needs to extrapolate observations at one scale to other scales. </p><p>Results are based on data observed in the Blue Lias in Somerset (UK), in Fumanya mine (Spain) and in a 3D seismic reflection survey in the Bonaparte Basin (Australia). Fault segmentation is investigated quantitatively based on previously established methodologies and we focus on neutral relay zones observed between fault segments along the strike of the normal faults.</p><p>We found that there are quantitative indications that the shape of the relay zones, the breaching of the relays and the degree of segmentation are all scale independent in Kilve and Fumanya. We propose that this is related to the low variability across scales in the geological parameters controlling segmentation, due to the relative homogeneity of the rock medium across the studied scales, the lack of influence of pre-existing faults or fractures, and the similar deformation histories for all studied faults. By contrast, faults show scale dependency in the Bonaparte Basin where large faults are under the influence of an oblique reactivation of pre-existing faults. Independently of the area, segmentation observed continuously through scale stresses the need to take into account resolution of observation in discussing fault development.</p>

Experimental investigation on the tensile properties of weakly cemented sandstone in China Shendong Mining Area

To investigate the tensile properties of weakly cemented rock samples at Shendong Mining Area. Four common weakly cemented rocks are subjected to Brazilian Splitting Test, and both the acoustic emission signals and deformation field are monitored simultaneously. Thus, deformation and acoustic emission features were analyzed in different rock samples. Moreover, the relationship between the evolution of localization belt and acoustic emission features was identified. The results show that the samples displayed similar deformation features and that the evolution of R value is also basically consistent.

Unconventional Deformation Behaviours of Nanoscaled High-Entropy Alloys

The bulk high-entropy alloys (HEAs) exhibit similar deformation behaviours as traditional metals. These bulk behaviours are likely an averaging of the behaviours exhibited at the nanoscale. Herein, in situ atomic-scale observation of deformation behaviours in nanoscaled CoCrCuFeNi face-centred cubic (FCC) HEA was performed. The deformation behaviours of this nanoscaled FCC HEA (i.e., nanodisturbances and phase transformations) were distinct from those of nanoscaled traditional FCC metals and corresponding bulk HEA. First-principles calculations revealed an obvious fluctuation of the stacking fault energy and stability difference at the atomic scale in the HEA. The stability difference was highlighted only in the nanoscaled HEA and induced unconventional deformation behaviours. Our work suggests that the nanoscaled HEA may provide more chances to discover the long-expected essential distinction between the HEAs and traditional metals.

Shortening the Long Creep Strength Evaluation Period with the Assistant of Stress Relaxation Behavior

P92 heat-resistant steel was used to demonstrate that creep rupture life evaluation period could be shorted by the assistant of the creep data from short-period stress relaxation test without reducing the prediction precision. Research showed that the minimum creep rate and the relaxation creep rate were exchangeable, and the stress exponent and the apparent activation energy analysis of the constant strain creep and the constant stress creep showed a similar deformation mechanism at the condition of T and . The creep rupture life predicted through the combination of these two kinds of creep data was closer to the real creep data than that evaluated by the traditional method based on the time to rupture only, and the precision of the evaluated creep strength increased at last 14.5 %.

Deformation of nickel-titanium closed coil springs: an in vitro study

ABSTRACT Objective: The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs. Methods: A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically. The values were compared by analysis of variance and Tukey's post-hoc test. Results: Springs manufactured by Morelli had the same amount of deformation when they were activated up to 700% of Y activation; springs by Orthometric had the same amount of deformation up to 600-700% of Y; springs by Ormco had the same amount of deformation up to 700-800% of Y; and finally, the majority of springs by GAC had similar deformation up to 800%-1000% of activation. All springs tested could be activated up to 700% without rupture. Conclusions: Most subgroups were similarly deformed up to 700% of activation, without rupture of springs. Subgroups 4B, 4C, 4D and 4E showed the same amount of deformation up to 1000% of activation without any rupture at all.

The Solution to the Safety Factor of Vertical Shaft Enclosure with One-Side Elevation Angle Based on FLAC3D

The enclosure structure of the vertical shaft of subway engineering is generally vertical, and perpendicular to the plane. Due to the effects of the geological condition, the construction condition and the supporting method, the shaft reflects similar deformation characteristics to the enclosure structure of foundation pit. Generally, the enclosure structure deformation can be decomposed into three types, namely the forward rotation, reverse rotation and deflection. When the vertical shaft enclosure structure produces a forward rotation with a lesser degree, it can still be used for positive angle slope processing, which enables us to calculate the safety factor of one side with positive angle enclosure structure in the same way with the slope of foundation pit. Taking the shield-receiving shaft of Dalian Jiaotong university station, Dalian metro No.2, Section 201 as an example, it is the geological conditions and supporting structure that contribute to build the enclosure structure with one-side elevation angle. Based on the above method and taking the geological, construction and supporting conditions into account, FLAC3D is used to build the model, and carry out the solution on safety factor of the enclosure structure with positive angle. The results indicate that under the existing conditions, the enclosure structure safety factor for our example is more than 1.

DEFORMATION AND WEAK DECAY OF Λ HYPERNUCLEI

We use the self-consistent mean-field theory to discuss the ground state and decay properties of Λ hypernuclei. We first discuss the deformation of Λ hypernuclei using the relativistic mean-field (RMF) approach. We show that, although most of the hypernuclei have a similar deformation parameter to the core nucleus, the shape of 28 Si is drastically altered, from oblately deformed to spherical, if a Λ particle is added to this nucleus. We then discuss the pionic weak decay of neutron-rich Λ hypernuclei using the Skyrme Hartree-Fock + BCS method. We show that, for a given isotope chain, the decay rate increases as a function of mass number, due to the strong neutron-proton interaction.

Deformation Characteristics in AlphaType Brass Worked by Torsion

In present work, bar samples of pure copper and Cu-Zn alpha single phase alloys setting 20mm in diameter and 150mm in length processed by torsion in the rotation speed to 1rpm every 60° twist angles. Then, deformed samples were researched microstructure and their characteristics. Microstructures of non-deformation samples were isometric, however, deformed samples streaky. Elements of bar drawn 10×10mm mesh were developed parallelogram. It was trend angle of between stretchable direction in microstructures and torsion axis increased more torsion angles. It was coincident with between the angle and deformed direction of microstructures. Shear strain was calculated by twist angle by theoretical formula. Their value corresponded rough with measurement from mesh variation. Pure copper and Cu-Zn alpha phase alloys were similar deformation microstructure, but fracture twist angle in copper was more than Cu-Zn alloys, and it was trend fracture angle had decreased as concentration of Zn increased. This trend was difference of fracture elongation obtained in tensile test.