Bottom Block Research Articles

Влияние расстояния между выпускными выработками на потери руды от смерзания при выпуске

The paper considers the results of experimental studies of changes in the ore losses caused by congealing in the stoping zone during the drawing process in conditions of subzero temperatures in underground mining of eore deposits in the cryolithic zone, depending on the distance between the draw holes. Three series of experiments were performed using trench-shaped test benches with various distances betwen the draw holes. The distances between the access crosscuts were assumed to be 180, 200 and 220 mm, which is equal to 9, 10 and 11 m in actual conditions according to the adopted geometric scale of modeling. The results of modeling the bottom drawing in conditions of subzero temperatures, similar to the conditions of the underground ore mining in the cryolithic zone, showed that changes in the distance between the draw holes with the trench-shaped design of the bottom block have a significant impact on the extraction rates. When the distance between the draw holes is increased from 9 m to 11 m, the ore loss due to congealing during the draw phase rises from 24% to 42%. Experimental studies have shown that the increased distance between the draw holes in conditions of subzero temperatures in the bottom area leads to increased ore losses caused by congealing in the stoping area.

Explosive weld joint characteristics of Copper-Tantalum via simulation

This report aims to examine the effects of impact velocity, impact depth, and impact orientation on the Cu–Ta weld joint of the explosive welding process via MD simulation. The findings indicate that the residual shear stress in the welded block mostly increases as the impact velocity rises. The bottom Ta block is more severely distorted than the higher Cu block due to the impact direction. During the tensile test, three stress zones can be identified including the low-stress Cu block, the high-stress Ta block, and the medium-stress weld joint in the middle of the samples. The weld joint position is lower than the median line of the welded block. The Cu–Ta welded block with 500 m/s impact velocities had the highest ultimate tensile strength (UTS) value of 6.49 GPa. With increasing impact depth, the atomic strain level, residual shear stress, and weld joint dimensions all noticeably increase. The Cu–Ta welded block with an impact depth of 7.5 Å has the greatest UTS values, measuring 11.65 GPa, because of its well-crystal structure. Changing the impact orientation does not result in a dramatic change in atomic strain. Orientation (001) vs (001) has the highest strain and stress rates. With an impact orientation of (110) vs. (111), the Cu–Ta welded block gets the highest UTS value of 8.03 GPa compared to other orientations.

New type of coatings combining invisibility and high power laser protection function

With the rapid development of laser technology, the protection of high-energy lasers has received increasingly widespread attention. The current laser protection methods only have single function, and do not consider the detection technology. Based on this, this article proposes a bilayer coating system that combines invisibility and high energy laser protection performance. For surface layer, four types of carbon materials were used as fillers and two types of resins were used as base materials. For the bottom layer, both YSZ block and YSZ plasma sprayed coating were used. The results show that the carbon material in surface layer react with oxygen rapidly under laser irradiation conditions, achieving the rapid transition from invisible state to laser protection state. This bilayer coating has simple process and low cost, leading to great application value. Meanwhile, this method also provides inspiration for the design and preparation of other multifunctional coatings.

New mapping for determination of left atrial posterior wall isolation for non-paroxysmal atrial fibrillation

Abstract Background Recent studies have reported that the efficacy of posterior wall isolation(PWI) created by cryoballoon for non-paroxysmal atrial fibrillation. However, there are no clear criteria for determining whether or not to perform PWI, and it is left to the discretion of the operator. Then we evaluated the necessity of additional PWI by measuring non-passively activated ratios(%NP), the ratio of the form of rotors and multiple wavelets, using ExTRa mapping and verified its usefulness. Methods and Results 44 patients with non-paroxysmal atrial fibrillation who underwent cryoballoon ablation(CBA) were divided into two groups according to whether using ExTRa mapping(ExTRa group; 21 patients) or not(no-ExTRa group; 23 patients), and the long-term results were compared. In ExTRa group, ExTRa mapping was performed before PVI, after PVI, and after roof block(LA-RB) creation using cryoballoon. After creating LA-RB, if more than 50% of %NP remained in the left atrium, PWI was performed by creating a bottom block(LA-BB) using cryoballoon. After a median follow-up period of 12months(2 to 34 months), arrhythmia-free survival rate was higher in the ExTRa group than in the no-ExTRa group(95.2% vs 69.6%, p<0.05%). Conclusion Evaluation of %NP using ExTRa mapping is extremely useful in determining the additional PWI for non-paroxysmal atrial fibrillation.Voltage mapping & ExTRa mapping

Mechanical performances of shield tunnel segments under asymmetric unloading induced by pit excavation

To explore the stress and deformation responses, as well as the failure characteristics of the shield tunnel segment of Hangzhou Metro under the influences of pit excavation and other surrounding projects, a self-developed “shield tunnel segment hydraulic loading system” was used to carry out full-scale loading tests on the three-ring staggered assembled segments. The structural performances and failure process of the tunnel segment under step-by-step asymmetric unloading were studied. A safety index was proposed to describe the bearing capacity of the segment. Next, a finite element model (FEM) was established to analyze the bearing capacity of segment using the test results. Finally, the effect of reinforcement with a steel plate on the deformation and bearing capacity of the segment was analyzed. The results showed that under asymmetric unloading, the peak value and amplitude of the bending moment on the near unloading side converged with a greater value than those on the far side. The concrete internal force exhibited a directional transformation at different load stages. Cracks first appeared at the 180° inner arc surface of the bottom standard block and then expanded to both sides, while the rate of crack propagation of the outer arc surface was relatively lower. The bearing capacity of the segments can be evaluated by the combination of the factors, e.g. the residual bearing capacity coefficient, moment transfer coefficient, and characterization coefficient. The segments approaching failure can facilitate the increase in the residual bearing capacity coefficient by more than 50%. This can provide guidance for the service assessment of metro tunnel operations.

Solving heat conduction problems in the start-up stage of direct chill casting processes via a temperature-enthalpy mixed formulation based on the improved element-free Galerkin method

A novel approach to solve the transient heat conduction problem with moving boundary and solid↔liquid phase change involved in the start-up stage of direct chill casting (DCC) processes is introduced in this work, which is based on the improved element-free Galerkin (IEFG) method. The procedure is developed under a temperature-enthalpy mixed formulation of the internal energy balance, but the construction of improved moving least squares (IMLS) is required only to approximate temperature. The reliability and suitability of this approach have been first proven in a 1-D alloy solidification benchmark problem with exact solution, and subsequently used to solve a more complex three-dimensional applied thermal problem concerning the start-up stage of the DCC process of an aluminium alloy slab. The domain growth conditioned by the bottom block (moving boundary) is modelled moving down the nodes used to represent the problem domain at each time step, and adding a new nodes plane at the domain upper boundary. Outcomes have revealed the usefulness of this technique to overcome the difficulties concerning solid↔liquid phase change marked non-linearities and moving boundaries involved in the transient analysis of DCC heat transfer problems, allowing the achievement of accurate and stable results in a remarkably simple manner.

RSU-Net: U-net based on residual and self-attention mechanism in the segmentation of cardiac magnetic resonance images

BackgroundAutomated segmentation techniques for cardiac magnetic resonance imaging (MRI) are beneficial for evaluating cardiac functional parameters in clinical diagnosis. However, due to the characteristics of unclear image boundaries and anisotropic resolution anisotropy produced by cardiac magnetic resonance imaging technology, most of the existing methods still have the problems of intra-class uncertainty and inter-class uncertainty. However, due to the irregularity of the anatomical shape of the heart and the inhomogeneity of tissue density, the boundaries of its anatomical structures become uncertain and discontinuous. Therefore, fast and accurate segmentation of cardiac tissue remains a challenging problem in medical image processing. MethodologyWe collected cardiac MRI data from 195 patients as training set and 35patients from different medical centers as external validation set. Our research proposed a U-net network architecture with residual connections and a self-attentive mechanism (Residual Self-Attention U-net, RSU-Net). The network relies on the classic U-net network, adopts the U-shaped symmetric architecture of the encoding and decoding mode, improves the convolution module in the network, introduces skip connections, and improves the network's capacity for feature extraction. Then for solving locality defects of ordinary convolutional networks. To achieve a global receptive field, a self-attention mechanism is introduced at the bottom of the model. The loss function employs a combination of Cross Entropy Loss and Dice Loss to jointly guide network training, resulting in more stable network training. ResultsIn our study, we employ the Hausdorff distance (HD) and the Dice similarity coefficient (DSC) as metrics for assessing segmentation outcomes. Comparsion was made with the segmentation frameworks of other papers, and the comparison results prove that our RSU-Net network performs better and can make accurate segmentation of the heart. New ideas for scientific research. ConclusionOur proposed RSU-Net network combines the advantages of residual connections and self-attention. This paper uses the residual links to facilitate the training of the network. In this paper, a self-attention mechanism is introduced, and a bottom self-attention block (BSA Block) is used to aggregate global information. Self-attention aggregates global information, and has achieved good segmentation results on the cardiac segmentation dataset. It facilitates the diagnosis of cardiovascular patients in the future.

Double Plane Direct Shear Apparatus for Determination of Adhesion Factor in Clays

Abstract A modified direct shear assembly with two parallel shear planes was designed to enable the simultaneous and independent measurement of cohesive and adhesive resistance; it is named the “double-plane direct shear device.” The three-block specimen box of the device has top and middle blocks filled with soil specimen and the bottom block is made of solid steel. The middle box is laterally displaced while restraining the top and bottom box, leading to concurrent shearing along two parallel shear planes. Results from quick undrained testing of kaolinite at five different consistency indexes (Ic) and three different vertical stresses (σv) are presented. The stress–deformation curves show greater mobilization of adhesive stress than cohesive stress at low deformations at all Ic and σv. The deformation required for the complete mobilization of cohesive and adhesive stresses and their variation with Ic and σv is discussed. A parameter crossover deformation (dco) is defined to identify the region where adhesive stress is greater than cohesive stress, which would be useful in applications where soil stickiness is of concern. The results show that the presence of partial drainage increases the dco, which results in an increased deformation range over which adhesive stress is greater than cohesive stress, thereby increasing the stickiness susceptibility. Furthermore, results show that the adhesion factor (α, defined as the ratio of adhesion to undrained cohesion) always stayed below unity under undrained conditions, whereas under partial drainage conditions, values of α greater than unity were obtained. The study concludes that for the application where soil stickiness is of concern, the determination of α and its usage to analyze stickiness susceptibility should be performed under simulation of appropriate drainage boundary conditions.

Ablation Index Guided Left Atrial Posterior Wall Isolation

Ablation index (AI)-guided linear ablation is reported to be feasible.We assessed the feasibility of AI-guided left atrial (LA) posterior wall isolations (PWIs) using different target AI values.Seventy-one persistent atrial fibrillation patients who underwent AI-guided PWIs following pulmonary vein isolation were included. LA linear lesions were created with strict contiguity (inter-lesion distance < 4 mm) and different predetermined AI target values (Group-1: 430, Group-2: 450). The data was analyzed retrospectively.The total radiofrequency application time of the roof and bottom-line ablation was a median of 2.8 (2.0, 3.8) and 3.6 (2.8, 4.3) minutes. The first-pass PWI success rate (26/35 [74.3%] versus 16/36 [44.4%], P = 0.011) and a first-pass roof line block (28/35 [80.0%] versus 21/36 [58.3%], P = 0.048) were significantly higher in Group-2 than Group-1, but that for the first-pass bottom line block was similar between Group-1 and Group-2 (29/36 [80.6%] versus 29/35 [82.9%], P = 0.80). Successful PWIs were achieved by additional applications in all. The significant parameter associated with a successful first-pass LA roof line block was a greater RF power, and that for the LA bottom were a higher radiofrequency power and shorter inter-lesion distance. Conduction gaps were mostly located at the middle of both lines. Among 22 roof line gaps, 12 were closed on the line whereas 10 (45.4%) required ablation inside the posterior wall for PWIs. On the contrary, all 11 gaps on bottom lines were closed on the line.Successful first-pass PWIs were obtained in 74% of patients using a target AI value of 450 and strict criteria for the lesion contiguity.

Construction of Garden Landscape Design System Based on Multimodal Intelligent Computing and Deep Neural Network.

The problem of module discrimination and identification in the field of landscape design is the focus of researchers. Based on multimodal intelligent computing, this paper constructs a landscape design system based on deep neural network. The article first uses a deep neural network to train multimodal garden landscape images, and then performs pooling and convolution operations on garden landscape images on the multimodal training model of convergence speed on the edge and solve the problem of low model accuracy. In the simulation process, the neural network module of MATLAB software is used to extract the spatiotemporal features of the dynamic garden landscape image from the three directions of the bottom block of the garden to achieve feature complementarity. This method only uses 15% of the features of the original feature set. The complexity of the recognition system also reduces the recognition error rate. The experimental results show that by adopting the design of feature series fusion, maximum value fusion, and multiplicative fusion in the score layer, the feature series fusion achieves a high accuracy rate under the multiplicative fusion of the three modalities, reaching 77.1%, and the test error is within 0.118, which effectively improves the multimodal characteristics of the integrated landscape and makes the modeling results more accurate.

Concrete-to-concrete shear friction behavior under cyclic loading: experimental investigation.

This study investigated the concrete-to-concrete friction behavior under dynamic cyclic loading at different loading rates, vertical loads, and surface roughness. The present work answers essential questions about the dynamic behavior of concrete-to-concrete friction since most of the available literature deals with static or quasi-static loading conditions. To this end, an experimental program was devised by casting 96 concrete blocks. A total of 48 dynamic push–pull tests were performed on each pair of blocks (mobile top block and fixed bottom block). Test variables included three types of surface roughness, four different loading rates, and two normal stresses. Performance measures included the static and dynamic friction forces coefficients of static and kinetic friction in addition to effective stiffness and effective damping. Moreover, the test results showed that the static and kinetic friction coefficients, effective stiffness, and effective damping decrease with increasing loading rates. Moreover, increasing the normal stress increases the friction force, thus increasing the effective stiffness and reducing the effective damping surface for all surface roughness types. The effects of test variables on the hysteresis behavior were also investigated.

Evaluation of Dibenzocyclooctyne and Bicyclononyne Click Reaction on Azido‐Functionalized Antifouling Polymer Brushes via Microspotting

AbstractStrain‐promoted alkyne‐azide cycloaddition (SPAAC) has become an indispensable tool in bioorthogonal conjugation and surface immobilization. While numerous studies have focused on enhancing the reactivity of cyclooctynes, a facile method to evaluate the binding efficiency for cyclooctyne‐azide‐based immobilization without any sophisticated facilities is still missing. In the present work, different derivatives of dibenzocyclooctyne/bicyclononyne (DBCO/BCN) linked to either a fluorophore or a biotin‐moiety are patterned on ultra‐low fouling polymer brushes, which can avoid unspecific protein contamination without any prior blocking steps. The polymer brushes are composed of an antifouling bottom block and azide‐terminated top block. The assessment of binding efficiency is conducted on ordered arrays spotted by microchannel cantilever spotting (μCS) with a normal fluorescent microscope. Both cyclooctynes demonstrate reliable binding performance with azide‐bearing diblock polymer brushes via μCS, but DBCO shows a higher surface density of molecular immobilization according to the protein binding assays. This work provides a reference for choosing appropriate cyclooctyne to couple with azides and can be useful for the design of biosensors or bio‐platforms for analyte detection, cell capture, and other biological applications.

Oriented immobilization of Pep19-2.5 on antifouling brushes suppresses the development of Staphylococcus aureus biofilms

Bacterial colonization of indwelling medical devices poses a danger to the patient and is a tremendous economic burden that costs billions of dollars to the healthcare system. Thus, it is essential to develop an effective mechanism that prevents the attachment of bacteria to the surface in combination with bactericidal strategies to kill them in direct contact. In this work, we combine the repellent/antifouling properties of polymer brushes with the antimicrobial activity of the synthetic peptide Pep19-2.5 and test its efficacy to inhibit Staphylococcus aureus biofilm formation. To tackle this, we utilized hierarchical polymer brushes, where the bottom block provides an effective barrier against adhesion while the top block provides functional groups for the immobilization of active molecules. Further, these polymer brushes were decorated with dibenzocyclooctine (DBCO)-functionalized Pep19-2.5 using strain-promoted alkyne-azide cycloaddition (SPAAC). This click chemistry proceeds very fast and does not require any catalyst, which is crucial for biomedical applications. The obtained coating was not only able to decrease the number of freely planktonic bacteria in the surrounding media (by 52.5%) but also inhibit the development of S. aureus biofilm by reducing the number of total, viable, and viable but non-culturable (VBNC) cells (up to 58%, 66%, and 70% respectively) and reduce the biovolume and thickness. Conversely, this coating does not exert any cytotoxic effect on Normal Human Dermal Fibroblasts (NHDF) cells. Thus, the combination of hierarchical polymer brushes with Pep19-2.5 is a promising approach to fight medical biofilms without affecting surrounding tissues.

P9. A distraction-based bench top protocol for the evaluation of growing rod concepatients

P9. A distraction-based bench top protocol for the evaluation of growing rod concepatients

Experimental study on the velocity-dependent frictional resistance of a rough rock fracture exposed to normal load vibrations

Changes in shear velocity can strengthen or weaken the frictional resistance of joints/faults in natural systems, but the mechanism remains unclear. We investigated the shear behavior of a rough basalt fracture in well-controlled, repeatable shear tests under constant and dynamic normal load conditions at different shear velocities. Normal load vibrations, simulating a dynamic normal load, were applied to the upper block of a fractured basalt sample. Simultaneously, a shear load was applied to the bottom block, providing a constant shear velocity. The peak shear strength increased with increasing shear velocity under constant normal load conditions. The peak shear strength decreased at a lower shear velocity under normal load vibrations. When the shear velocity exceeded the critical value, vc, the peak shear strength increased. The apparent coefficient of friction reduced under normal load vibrations. The reduction in the dynamic coefficient of friction increased with increasing shear velocity. We identified a phase shift between the peak normal load and peak shear load with peak shear load delay (D1) and a phase shift between peak normal load and the peak coefficient of friction with the peak coefficient of friction delay (D2). D1 and D2 were dependent on the quasi-static coefficient of friction and shear velocity, and both decreased with increasing shear velocity. D1 decreased with the increasing quasi-static coefficient of friction, while D2 was almost constant with changes in the quasi-static coefficient of friction. A new shear strength criterion was proposed for a rough joint under a constant shear velocity and normal load vibrations.

Stress analysis bottom plate block B-03 on patrol ship construction using finite element methods

On the process of constructing ships with the block system has a tendency to dealing time production process for assembly. The waiting time makes the construction of the bottom plate to receive the burden during the waiting time so that the deformation often occurs due to excess stress received. The purpose of this study to know the stress value of the bottom construction of a block due to the static load on the ship building process. The method used is the Finite Element method is a form of the approximation method commonly used to solve an equation numerically in a stress analysis. The variables used in this study are the different types of meshing, the number of focuses on stop block. Based on the results start of the construction stress analysis Plate Bottom block B-03 on the construction of patrol ship. Obtained the highest stress value in the use of 4 stop block so, it is advisable to increase the number of stop blocks in order to reduce the results of excessive deformation.

Dimensions of Thermal Inequity: Neighborhood Social Demographics and Urban Heat in the Southwestern U.S.

Exposure to heat is a growing public health concern as climate change accelerates worldwide. Different socioeconomic and racial groups often face unequal exposure to heat as well as increased heat-related sickness, mortality, and energy costs. We provide new insight into thermal inequities by analyzing 20 Southwestern U.S. metropolitan regions at the census block group scale for three temperature scenarios (average summer heat, extreme summer heat, and average summer nighttime heat). We first compared average temperatures for top and bottom decile block groups according to demographic variables. Then we used spatial regression models to investigate the extent to which exposure to heat (measured by land surface temperature) varies according to income and race. Large thermal inequities exist within all the regions studied. On average, the poorest 10% of neighborhoods in an urban region were 2.2 °C (4 °F) hotter than the wealthiest 10% on both extreme heat days and average summer days. The difference was as high as 3.3–3.7 °C (6–7 °F) in California metro areas such as Palm Springs and the Inland Empire. A similar pattern held for Latinx neighborhoods. Temperature disparities at night were much smaller (usually ~1 °F). Disparities for Black neighborhoods were also lower, perhaps because Black populations are small in most of these cities. California urban regions show stronger thermal disparities than those in other Southwestern states, perhaps because inexpensive water has led to more extensive vegetation in affluent neighborhoods. Our findings provide new details about urban thermal inequities and reinforce the need for programs to reduce the disproportionate heat experienced by disadvantaged communities.

Mitigation of hunchbacked gravity quay wall displacement due to dynamic loading using shaking table tests

Five reduced-scale shaking table tests have been performed to investigate the deformation behavior of a block type quay wall under strong earthquakes. The quay wall was resting on a high relative density inclined seabed. The underlying seabed inclination and bottom block slopes have been considered as two parameters for mitigating the wall displacement. The experimental results indicated that the dominant mode of the wall failure under strong base acceleration was the sliding of the wall. Increasing the bottom block inclination (from 0 to 10°) significantly decreased the lateral displacement and the backfill settlements, which can increase the safety of port facilities. Since the high bottom inclination can cause the wall to overturn, a 7-degree angle was selected as the optimal degree for the presented wall model. Furthermore, it was observed that, making the bottom block inclined, without the seabed being inclined, did not effectively reduce the wall displacement.

A Gap Waveguide-Based Compact Rectangular Waveguide to a Packaged Microstrip Inline Transition

In this paper two different simple to design and easy to manufacturing transitions from a microstrip to rectangular waveguide based on ridge and groove gap waveguides are studied. The first one is based on a combination of a groove and ridge gap waveguide. In this case, the microstrip substrate occupies the whole bottom metallic housing block, namely, the transition and the gap between the bed of nails and the lid; therefore, it does not require any substrate shaping. Nevertheless, the transition needs to replace groove waveguide by ridge gap waveguide sections to avoid higher-order mode excitation. In the second approach, based on only a groove gap waveguide, the substrate is shaped to be only in the microstrip section, that is, outside the bed of nails area. This leads to a simplification of the design procedure. Prototypes of both transitions have been characterized, showing good agreement with the simulations taking into account the manufacturing tolerances. Performance comparable to the state-of-the-art in this frequency band has been achieved.

Highly non-linear solitary wave imaging method for detecting cylindrical defects in the metal plate of an adhesive composite metal structure

In this paper, a non-destructive testing (NDT) method based on highly non-linear solitary waves (HNSWs) was employed to detect defects in the metal plate of an adhesive composite metal structure. Firstly, HNSWs were generated by applying impulses to a one-dimensional granular chain of steel spheres. Proof-of-concept finite element (FE) simulations were then performed using Abaqus software to investigate the reflection behaviour of HNSWs at the interface of the chain and the two-layer material with defects. The time-of-flight (TOF) of primary reflected solitary waves (PSWs) was confirmed as a good indicator for defect localisation and sizing. A HNSW generator and detector device was used in the experiment and HNSW B-scan and C-scan inspections of adhesive composite steel specimens were achieved. The TOF imaging results accurately indicated the locations of cylindrical defects in the bottom steel block. The linear correlation between the peak value of the pulsed TOF profile and the defect diameter was determined. The contours of TOF with different values were introduced to reconstruct the shape of the circular defective region. Through selecting the correct threshold of TOF, the relative error of the area surrounded by the contour compared to the actual area of the five investigated defects could be less than 6.5%.