Block Shape Research Articles

Performance Evaluation of Feature Matching Techniques for Detecting Reinforced Soil Retaining Wall Displacement

Image registration technology is widely applied in various matching methods. In this study, we aim to evaluate the feature matching performance and to find an optimal technique for detecting three types of behaviors—facing displacement, settlement, and combined displacement—in reinforced soil retaining walls (RSWs). For a single block with an artificial target and a multiblock structure with artificial and natural targets, five popular detectors and descriptors—KAZE, SURF, MinEigen, ORB, and BRISK—were used to evaluate the resolution performance. For comparison, the repeatability, matching score, and inlier matching features were analyzed based on the number of extracted and matched features. The axial registration error (ARE) was used to verify the accuracy of the methods by comparing the position between the estimated and real features. The results showed that the KAZE method was the best detector and descriptor for RSWs (block shape target), with the highest probability of successfully matching features. In the multiblock experiment, the block used as a natural target showed similar matching performance to that of the block with an artificial target attached. Therefore, the behaviors of RSW blocks can be analyzed using the KAZE method without installing an artificial target.

Analysis of the regularities of basalt open-pit fissility for energy efficiency of ore preparation

Purpose. To identify dependence of specific rock mass fissility upon the bench height of basalt open pits based upon the analysis of basalt open-pit bench fissility. Methods. Fractural tectonics of basalt open pits was studied experimentally. In addition to the specific fissility, the studies determined both shape and quantity of natural blocks within each bench meter; their geometry in terms of fissure frequency; and nature of changes in the fissure number as well as geometry of the blocks depending upon a bench height. Graphical analysis of the obtained results has helped determine the typical dependencies of fissure number upon the changes in the open-pit bench height. Findings. It has been defined that the specific fissility of basalt benches is distributed irregularly in terms of an open-pit bench height. Field studies, involved three basalt open pits, have made it possible to identify that the 3rd degree polynomial is the most adequate approximation of the specific fissility dependence upon the bench height. Originality. For the first time, the experiments have helped define that rock mass joints a share downward from the smaller to the larger ones following a parabolic law (according to a cubic expression). The obtained regularities help identify the percentage of shares of three sizes for each bench height meter. Practical implications. Estimate of share percentage will make it possible to schedule rationally the drilling and blasting operations while selecting energy efficient parameters of production facilities for further basalt processing.

Three-axial shape distributions of pebbles, cobbles and boulders smaller than a few meters on asteroid Ryugu

Over a broad size range, the shapes of impact fragments from catastrophic disruptions are distributed around the mean axial ratio 2: √2: 1, irrespective of experimental conditions and target materials. Although most blocks on asteroids are likely to be impact fragments, there is not enough quantitative data for reliable statistics on their three-axial lengths and/or ratios because it is difficult to precisely estimate the heights of the blocks. In this study, we evaluate the heights of blocks on asteroid Ryugu by measuring their shadows. The three-axial ratios of ~4100 small blocks with diameters from 5.0 cm to 7.6 m in Ryugu's equatorial region are investigated using eight close-up images of narrower localities taken at altitudes below 500 m, i.e. at <5.4 cm/pixel resolution, obtained immediately before the second touch-down of the Hayabusa2 spacecraft. The purpose of this study is to investigate the block shape distribution, which is important for understanding the geological history of asteroid Ryugu. Specifically, the shape distribution is compared to laboratory impact fragments. Our observations indicate that the shape distributions of blocks smaller than 1 m on Ryugu are consistent with laboratory impact fragment shape distributions, implying that the dominant shape-determining process for blocks on Ryugu was impact fragmentation. Blocks several meters in size in the equatorial region seem to be slightly flatter than the rest, suggesting that some blocks are partly buried in a bed of regolith. In conclusion, the shape distributions of blocks from several-cm to several-m in the equatorial region of asteroid Ryugu suggest that these are mainly fragments originating from the catastrophic disruption of their parent body and/or from a later impact.

Self-assembly of colloidal cube superstructures with critical Casimir attractions

The structure of self-assembled materials is determined by the shape and interactions of the building blocks. Here, we investigate the self-assembly of colloidal ‘superballs’, i.e. cubes with rounded corners, by temperature-tunable critical Casimir forces to obtain insight into the coupling of a cubic shape and short range attractions. The critical Casimir force is a completely reversible and controllable attraction that arises in a near-critical solvent mixture. Using confocal microscopy and particle tracking, we follow the self-assembly dynamics and structural transition in a quasi-2D system. At low attraction, we observe the formation of small clusters with square symmetry. When the attraction is increased, a transition to a rhombic Λ1-lattice is observed. We explain our findings by the change in contact area at faces and corners of the building blocks combined with the increase in attraction strength and range of the critical Casimir force. Our results show that the coupling between the rounded cubic shape and short-range attraction plays a crucial role for the superstructures that form and provide new insights for the active assembly control of micro and nanocubes.

Feasibility experiments of seismic concrete block walls without joint mortar

The authors developed two types of block systems consisting only of main block and key block without joint mortar in consideration of seismic performance and workability. Two types of block systems have different key block shapes: One is the peanuts shape and the other is the dumbbell shape. In this study, the proposed two types of block walls as well as a typical block wall were experimentally investigated to evaluate the seismic performance. In the tests, full-scale, single-story specimens were tested under static cyclic in-plane loading, and failure patterns and cracks were carefully observed. In this paper, the loading bearing capacity, energy dissipation capacity and reuse ratio of block walls are discussed in detail. As a result, the deformability, energy absorption capacity and reuse ratio of the proposed block systems were considerably higher than those of typical block system.

Numerical investigation of railway subgrade stiffening: Critical speed and free-field vibrations

For a train speed close to the speed of elastic waves in the soil, often referred to as “critical speed”, largely elevated vibration responses occur. This can be a practical problem for soft soil sites, where the phenomenon may cause excessive vibrations in the track and also at distances far from the track. To ensure the running safety of the train, the long-term quality of the track and to reduce the vibrations in the surroundings, such effects must be avoided. An effective counter-measure is to increase the stiffness of the soil underneath the track, thereby increasing the critical velocity.In this paper, a 2.5D finite element model is used for studying the critical velocity phenomenon and its mitigation through soil stiffening, for a ballasted track on a layered half-space with very soft soil. Soil improvement under the track, in the shape of a solid block or as various number of panels, with varying depth and stiffness is considered. The effect of the soil improvement is evaluated both in terms of the maximum rail and free-field displacements. It is shown that a shallow soil stiffening increases the critical velocity and reduces the rail and free-field response for load speeds near the shear wave velocity of the soft top soil layer. It is also demonstrated that a deep soil stiffening, by use of panels along the track direction, increases the critical velocity further, and may also be efficient in reducing the response for load speeds near the shear wave speed of the underlying half-space.

Discrete Element Bonded-Block Models for Detailed Analysis of Masonry

A detailed modelling approach to represent masonry at the meso-scale is proposed, based on the discrete element method, considering the nonlinear behavior of the joints and the units. The fracture of units is represented by the bonded-block concept, in which a random network of potential cracks is created, allowing the progressive development of failure mechanisms. For simplicity, only the 2D case is presented, but the extension to 3D is straightforward. A key component of the proposed model is a framework for a joint or interface constitutive model, including the post-peak softening range, taking into account the experimental fracture energies. In this model, the softening curves in tension or shear are defined by piecewise linear segments, calibrated to reproduce the most common masonry constitutive models. The essential issues involved in the application of bonded-block models to masonry are examined, namely the block shape, either Voronoi polygons or triangles; size; deformability; and the influence of the main constitutive parameters. Uniaxial compression tests are analyzed in detail. The simulation of a well-known experiment of a brick panel under shear shows the good performance of the proposed approach. The investigation results demonstrate the model’s capabilities and provide guidelines for its application.

Promotional catalytic activity and reaction mechanism of Ag-modified Ce0.6Zr0.4O2 catalyst for catalytic oxidation of ammonia

Ce1-xZrxO2 composite oxides (molar, x = 0-1.0, interval of 0.2) were prepared by a cetyltrimethylammonium bromide-assisted precipitation method. The enhancement of silver-species modification and catalytic mechanism of adsorption-transformation-desorption process were investigated over the Ag-impregnated catalysts for low-temperature selective catalytic oxidation of ammonia (NH3-SCO). The optimal 5 wt.% Ag/Ce0.6Zr0.4O2 catalyst presented good NH3-SCO performance with >90% NH3 conversion at temperature (T) ≥ 250°C and 89% N2 selectivity. Despite the irregular block shape and underdeveloped specific surface area (∼60 m2/g), the naked and Ag-modified Ce0.6Zr0.4O2 solid solution still obtained highly dispersed distribution of surface elements analyzed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) (mapping), N2 adsorption-desorption test and X-ray diffraction (XRD). H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) results indicated that Ag-modification enhanced the mobility and activation of oxygen-species leading to a promotion on CeO2 reducibility and synergistic Ag0/Ag+ and Ce4+/Ce3+ redox cycles. Besides, Ag+/Ag2O clusters could facilitate the formation of surface oxygen vacancies that was beneficial to the adsorption and activation of ammonia. NH3-temperature programmed desorption (NH3-TPD) showed more adsorption-desorption capacity to ammonia were provided by physical, weak- and medium-strong acid sites. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments revealed the activation of ammonia might be the control step of NH3-SCO procedure, during which NH3 dehydrogenation derived from NHx-species and also internal selective catalytic reduction (i-SCR) reactions were proposed.

Radiographic assessment of deproteinized bovine bone mineral (DBBM) and collagen-stabilized DBBM for transalveolar sinus floor elevation: A 2-year retrospective cohort study.

Theoretically, collagen-stabilized deproteinized bovine bone mineral (DBBM-C) has better operability compared with DBBM. DBBM-C avoids dispersing during the transalveolar sinus floor elevation (TSFE) because of its block shape. To evaluate radiological changes of using DBBM-C in TSFE. Patients who received TSFE using DBBM (Bio-Oss®) or DBBM-C (Bio-Oss® collagen) with simultaneous implantation were recruited. Graft bone height apically (aGH), endo-sinus bone gain (ESBG), and crest bone level (CBL) were assessed through panoramic radiograph and cone beam computed tomography (CBCT). A total of 138 patients (138 implants) were retrospectively enrolled. After 2 years of implantation, the incidence of postoperative complications was 4.2% (95% CI: 0.9%-11.7%) and 4.5% (95% CI: 0.9%-12.7%) for DBBM and DBBM-C groups, respectively. Measured in panoramic radiograph, ΔaGH of DBBM-C (1.8 mm, SD: 1.4, 95% CI: 1.2-2.4, P=0.044) group was significantly higher than that of DBBM (1.2 mm, SD: 1.4, 95% CI: 0.7-1.7) after 24 months. No significant differences for ΔCBL were noted during the entire observation period. Measured through CBCT, ESBG was 5.0 (SD: 1.8, 95% CI: 4.1-5.8) mm in DBBM group and 4.6 (SD: 1.6, 95% CI: 3.9-5.3) mm in DBBM-C group 24 months after implantation. The aGH value of DBBM-C group was significantly higher compared with DBBM in CBCT (OR=1.4, 95% CI: 1.1-1.9, P=0.020). DBBM-C could achieve similar bone generation as DBBM in TSFE. Both materials could maintain aGH, ESBG, and CBL relatively stable 2 years after implantation.

The Effect of Bismuth on Technological and Material Characteristics of Low-Alloyed Automotive Steels with a Good Machinability

The aim of this work is to compare the technological and material properties of CMnCr steels without bismuth, with 0.08 wt. % Bi and 0.12 wt. % Bi. Experimental heats showed that the most advantageous alloying of Bi into the heat was in the ladle, with an efficiency of about 20%. The optimal temperature range for forming steel was found to be 1160–1050 °C. With increasing Bi content, the formability of steels and plastic properties decreased, while the yield stress and tensile strength increased. Manganese sulfides, aluminum oxides, or oxysulfides, which were segregated both individually and in clusters, were found in the matrix of all tested steels. In steels with Bi, the Bi particles segregate the separately in the form of globules, either as envelopes of elongated MnS or Al2O3 particles segregated in rows. Sulfur dot-shaped segregations in the steel with 0.12 wt. % of Bi and the steel without Bi were essentially uniform over the whole area. For the steel with 0.08 wt. % of Bi, both dot-like and ray-ordered sulfur segregations were observed. The microstructure of all tested steels was ferritic–pearlitic with islands of bainite. Towards the center of the forged bars, variable shape and size of bainite blocks were observed. Machinability tests evaluated by the extend of tool wear showed that the most advantageous was CMnCr steel alloyed with 0.08 wt. % Bi.

Building Classification Algorithm Based on Improved Hough Transform and Geographic Information System

Although determining the type of building can be useful for 3D reconstruction, image retrieval, and other applications, it is often difficult to do so automatically. A building classification algorithm using a geographic information system (GIS) is proposed in this paper. The typical adjustment of building polygon, local convex-concave simplification of large-area polygon contour, and local exaggeration of competing polygon groups merging in small-area polygon is the main topics of this paper. The preliminary outline area is obtained by analyzing the corner characteristics of two basic types of buildings in urban buildings using a large-scale morphological screen. The classification statistics of all kinds of corners are carried out using the improved Hough transform and the proposed line segment and corner optimization algorithm, and the automatic classification of flat-roofed and nonflat-roofed buildings photographed by digital cameras is realized. The experimental results show that the algorithm simplifies the polygons in a reasonable way while maintaining the block shape. Furthermore, the optimization algorithm proposed in this paper effectively eliminates the influence of false contours, allowing for high-accuracy building type judgment.

Assessment of Waterfront Office Redevelopment Plan on Optimal Building Arrangements with Rooftop Photovoltaics: A Case Study for Shinagawa, Tokyo

Designing waterfront redevelopment generally focuses on attractiveness, leisure, and beauty, resulting in various types of building and block shapes with limited considerations on environmental aspects. However, increasing climate change impacts necessitate these buildings to be sustainable, resilient, and zero CO2 emissions. By producing five scenarios (plus existing buildings) with constant floor areas, we investigated how buildings and district forms with building integrated photovoltaics (BIPV) affect energy consumption and production, self-sufficiency, CO2 emission, and energy costs in the context of waterfront redevelopment in Tokyo. From estimated hourly electricity demands of the buildings, techno-economic analyses were conducted for rooftop PV systems for 2018 and 2030 with declining costs of rooftop PV systems. We found that environmental building designs with rooftop PV system are increasingly economical in Tokyo with CO2 emission reduction of 2–9% that depends on rooftop sizes. Payback periods drop from 14 years in 2018 to 6 years in 2030. Toward net-zero CO2 emissions by 2050, immediate actions are necessary to install rooftop PVs on existing and new buildings with energy efficiency improvements by construction industry and building owners. To facilitate such actions, national and local governments need to adopt appropriate policies.

Protein Needles Designed to Self-Assemble through Needle Tip Engineering.

The dynamic process of formation of protein assemblies is essential to form highly ordered structures in biological systems. Advances in structural and synthetic biology have led to the construction of artificial protein assemblies. However, development of design strategies exploiting the anisotropic shape of building blocks of protein assemblies has not yet been achieved. Here, the 2D assembly pattern of protein needles (PNs) is controlled by regulating their tip-to-tip interactions. The PN is an anisotropic needle-shaped protein composed of β-helix, foldon, and His-tag. Three different types of tip-modified PNs are designed by deleting the His-tag and foldon to change the protein-protein interactions. Observing their assembly by high-speed atomic force microscopy (HS-AFM) reveals that PN, His-tag deleted PN, and His-tag and foldon deleted PN form triangular lattices, the monomeric state with nematic order, and fiber assemblies, respectively, on a mica surface. Their assembly dynamics are observed by HS-AFM and analyzed by the theoretical models. Monte Carlo (MC) simulations indicate that the mica-PN interactions and the flexible and multipoint His-tag interactions cooperatively guide the formation of the triangular lattice. This work is expected to provide a new strategy for constructing supramolecular protein architectures by controlling directional interactions of anisotropic shaped proteins.

Research on the Influence of the Shape of an Object on Its Fluid Resistance

In the chapter on Fluids in Edexcel Physics, it is mentioned that different shapes have different effects on fluid resistance. In this study, the effect of the shape of the object on the fluid resistance is studied. Experimental methods are mainly used. In the experiment, by studying the movement speeds of different shapes of iron blocks in water, the different fluid resistances of different shapes of iron blocks were inferred, and the influence of different shapes on fluid resistance was further speculated. In the course of the experiment, different shapes of iron blocks were used, and weights and measuring cylinders were also used. The amount of resistance received is determined by measuring the length of time it takes for different iron blocks to move at a constant distance in water under constant tensile force. The final conclusion is that the more square the object moves in the fluid, the greater the fluid resistance is. The more sleek streamlined an object is, the less fluid resistance it is subjected to as it moves through the fluid.

Novel Pervious Concrete Paver Blocks for Sustainable Pavements

Abstract Pervious concrete pavements (PCPs) are known for their interconnected pores that provide environmental benefits. The high latent capacity, infiltration rate, and skid resistant riding surface highlight the benefits of pervious concrete as pavement material. PCPs are one of the best storm water management practices, but its implementation is still scarce. In this study, novel pervious concrete paver blocks were manufactured as per factory-based procedure and were tested for their properties. The experimental matrix included the shape of paver block, gradation (G1 and G2), water-to-cement ratio (w/c) and cement-to-aggregate (c/a) ratio as variables. The G2 gradation depicted higher density (1,900–2,450 kg/m3) than G1 (1,700–2,350 kg/m3) for the same mix composition. The w/c and c/a should be limited to 0.30 and 0.25, respectively, to avoid drain down of cement paste to the bottom of blocks due to their reduced thickness, which may otherwise render the blocks impervious. The infiltration rate varied over a range of 0.49 to 1.60 mm/s, depicted a lower variation as a function of shape, but significant variation was observed with respect to c/a and w/c. The compressive strength of the paver blocks varied as a function of shape and c/a ratio, where a strength of at least 15 MPa was achieved. The clogging study indicated there was an initial sudden reduction in the infiltration rate followed by a reduced rate of reduction, leading to a terminal infiltration rate (10–15 % of initial infiltration rate). Overall, the study aimed at providing an alternative approach to implement PCP in the form of interlocking blocks, which can be easily constructed with minimum machinery support.

How New Kids on the Block Shape Competition on the Battleground - Reversing Value Creation Strategies of Industrial Internet-of-Things Platforms

How New Kids on the Block Shape Competition on the Battleground - Reversing Value Creation Strategies of Industrial Internet-of-Things Platforms

Impact of lung block shape on cardiac dose for total body irradiation.

Evaluating cardiac dose during total body irradiation (TBI) is of increasing interest. A three-dimensional beam model for TBI was commissioned and lung shielding was simulated in a treatment planning system with the cardiac silhouette partially blocked and unblocked. When blocked, the median heart dose decreased by 6% (IQR=6%) and the median cardiac V12Gy decreased by 27% (IQR=17%). The median left anterior descending artery dose decreased 20% (IQR=12%) for blocked cases. Because using partial heart shielding may result in considerable changes in dose to cardiac structures, TBI protocols should explicitly consider lung block design parameters and their potential effects.

Lateral Impact Response of Elliptical Hollow and Partially Concrete-Filled Cold-Formed Steel Columns Under Static Axial Compression Load

In recent years, the use of partially concrete-filled steel tubular (PCFST) columns has been considered due to their cost-effectiveness and reduction of structural weight in bridge piers and building columns. One of the critical discussions about these columns is their impact resistance. In this article, the dynamic response of hollow and PCFST columns with elliptical cross-section under simultaneous loading of static axial compressive load and lateral impact load is presented using finite element modeling in ABAQUS software (FEA). To ensure the accuracy of the numerical modeling, the analysis results are compared with the results of previous works. The effects of different parameters such as impact velocity, the height of the impact location, the impact direction, the impact block mass, the size and shape of the impact block are investigated in this paper. The results of the numerical analysis showed that the partially filled specimens had better performance than the hollow specimens. The changes in impact direction and impact block mass parameters have a significant effect on the failure of the columns, especially when they are under high impact velocity. Changing the impact velocity significantly affects the impact resistance of specimens. However, the size and shape of the impact block did not have a significant effect on the displacement of the column against the impact loading.

A Stochastic Rockfall Model Related to Random Ground Roughness Based on Three-Dimensional Discontinuous Deformation Analysis

The use of feasible 3-D numerical methods has become essential for addressing problems related to rockfall hazard. Although several models with various degrees of complexity are available, certain trajectories and impact dynamics related to some model inputs could fall in the rockfall observations area but are rarely calibrated against reflecting its range, especially the lateral deviations. A major difficulty exists in the lack of simulating the apparent randomness during the impact-rebound process leading to both ground roughness and block irregularities. The model presented here is based on three-dimensional discontinuous deformation analysis (3-D DDA). Despite similarities to previous simulations using 3-D DDA, the model presented here incorporates several novel concepts: (1) ground roughness is represented as a random change of slope angle by height perturbation at a grid point in DEM terrain; (2) block irregularities are modelled directly using polyhedron data; (3) a scaled velocity restitution relationship is introduced to consider incident velocity and its angle. Lateral deviations of rebound velocity, both direction and value, at impact are similarly accounted for by perturbing the ground orientation laterally, thus inducing scatter of run-out directions. With these features, the model is capable to describe the stochastic rockfall dynamics. In this study, 3-D DDA was then conducted to investigate the dynamic behavior of the rockfall and examine the role of sphericity of the rock block travelling on bench slopes with different ground roughness levels. Parametric analyses were carried out in terms of cumulative distribution function (CDF) to investigate for spatial distribution (both runout distance and lateral displacement), velocity and jumping height. The effects of block shape and ground roughness revealed by these factors were discussed. It suggests that ground roughness amplifies the randomness and plays important roles on the dynamic behavior of the system; irregularity from block sphericity will further amplify the randomness especially when the size of the rock is relatively small compared to the roughness level. Both irregularities should be taken into consideration in simulating rockfall problems. Further calibration of the new model against a range of field datasets is essential.

A systematic framework for the 3D finite-discrete modelling of binary mixtures considering irregular block shapes and cohesive block-matrix interfaces

A systematic three-dimensional finite-discrete approach that considers realistic irregular blocks and cohesive block-matrix interfaces is proposed to simulate a binary mixture of geomaterials. First, the photogrammetry-based technique is employed to acquire realistic irregular block shapes, which are subsequently represented by spherical harmonics (SH). Next, the realistic binary mixture models are reproduced by random allocation of the SH-based irregular blocks into the sample domain. The cohesive zone model is employed to capture traction-separation responses of the block-matrix interface and to simulate progressive failure of the binary mixture. A hybrid model for the finite-discrete simulation of binary mixtures is established by inserting cohesive elements into the mesh model of binary mixtures. A series of basic mechanical tests are performed to calibrate modelling parameters and validate reliability of the proposed method. The proposed model shows great potential for addressing heterogeneous binary mixtures of geomaterials that maintain the characteristics of both continuity and discontinuity.