Support Columns Research Articles

Influence of bottom supporting columns and cooling rate on the surface shape characteristics of sapphire substrates

The manufacturing process of sapphire substrates involves several key steps, including epitaxy, annealing, cutting, and processing. Among these, epitaxy and annealing are particularly crucial. The temperature variances along both the longitudinal and transverse axes within the furnace during the crystallization process play a significant role in determining the crystallization rate and internal structure of sapphire crystals. Furthermore, annealing sapphire serves to alleviate internal stress, enhance crystal structure, optimize physical properties, improve optoelectronic characteristics, enhance surface quality, and increase overall yield. This step is paramount in enhancing the performance and application value of sapphire materials. In order to investigate and optimize the effects of different thermal conductivities of support columns at the base and various annealing procedures on the surface characteristics of sapphire substrates, thereby improving product quality, this study conducted research by utilizing support columns made of different materials and carefully controlling the cooling rate parameters for sapphire. The findings revealed that using graphite as the base support column for the crystal furnace can reduce both the longitudinal and transverse temperature gradients within the furnace, consequently promoting crystal growth and enhancing the quality of sapphire ingots. Additionally, sapphire chips annealed using the rapid one-step annealing program exhibited the highest average warpage and bending rate variation, reaching 2.0 μm, and the average dislocation density was half that of conventionally produced chips, at 108.89 pits/cm2.

Thermal performance analysis of supporting column ultra-thin vapor chamber with graded microgroove

To analyze the thermal behavior of a graded microgroove ultra-thin vapor chamber with supporting column, a three-dimensional steady-state numerical model coupled with graded capillary force network, which involves hydraulic and heat transfer on hydraulic and heat transfer performance on ultra-thin vapor chamber with different supporting column sizes. This model considers the influence of supporting column with varying diameters and intervals on liquid flow and temperature distribution, as well as the effects of a graded capillary force network on heat transfer limit of ultra-thin vapor chamber. The numerical results show that the additional heat transfer provided by the central support column causes an outward shift in the saturation temperature of vapor, creating a new liquid reflux path at the condensation surface. The accuracy of the model is verified by the preparation of ultra-thin vapor chamber with a graded microgroove a graded microgroove. Compared with the experimental results on conventional microgrooves, graded microgrooves can improve the heat transfer limit by 29.3%. According to the theoretical analysis model, the graded capillary force network can effectively resist incremental increases in vapor pressure drop, enhancing the efficiency of gas–liquid circulation of ultra-thin vapor chamber.

Analysis of the load‐bearing characteristics of hydraulic supports for top‐coal caving under the impact of coal and gangue

AbstractTo study the effect of different sizes and speeds of coal gangue falling on hydraulic supports for top‐coal caving discharge hydraulic support on the bearing characteristics of the hydraulic support, the ADAMS hydraulic support rigid‐flexible coupling analysis model was established. HyperMesh is used to flexibly process the hydraulic support, and the column and jack are equivalently replaced by spring damping system. By applying step loads of different sizes and speeds to simulate the impact force generated when the coal gangue falls on different positions of the cover beam, the dynamic response characteristics of the column, balance jack and other articulation points are obtained. Analyses show that: when the impact load is closer to the roof beam, the articulation point of the roof beam‐cover beam and the balancing jack are easy to be damaged. When the same impact load is applied to the cover beam, the faster the load is applied, the hydraulic support column and balancing jack may not be able to absorb and disperse the pressure effectively in time, resulting in the articulation points being subjected to a larger impact force, which is easy to cause damage or destruction. When different sizes and speeds of impact loads are applied to the cover beam, the latter has a greater impact on the dynamic response of the front and rear connecting rod articulation points and the cover beam‐roof beam articulation point than the former, and the hydraulic bracket will be more prone to vibration, deformation, and stress concentration, thus affecting the stability and safety of the bracket. The article is of guiding significance for designing and optimizing the structure and parameters of the hydraulic support, and improving the support performance and stability of the hydraulic support in the comprehensive release working face.

Structural visualization analysis applied to the preservation of architectural heritage: the case of stilted houses in southwest Hubei, China

Wooden buildings represent a unique aspect of China’s architectural heritage. However, over time, these buildings have suffered varying degrees of structural damage, particularly those located in China’s mountainous regions. Frequent natural disasters and inconvenient transportation further exacerbate the vulnerability of these structures. This study focuses on the typical wooden stilt houses found in the Wuling Mountain area of southwest Hubei. The different forms of columns and beams, as well as the overall structural symmetry of the stilt houses, were classified into five common structural types. Precise digital models were established via real photos and collected dimensional data, and these five models were evaluated for static, buckling, utilization, and ultimate limit states. The results indicate that: (1) overall symmetrical structures perform better than asymmetrical ones; (2) structures where all columns are grounded and act as support columns exhibit the best overall mechanical performance; and (3) transverse-tie beams(chuanfang) primarily serve a connecting role rather than a load-bearing role, thus an excess of transverse-tie beams(chuanfang) can reduce the stability of the building structure. Based on the analysis results, targeted protective measures and recommendations were proposed and verified through structural evaluations. These initiatives provide new methods and insights for the protection of architectural heritage.

Automated design of bone-preserving, insertable, and shape-matching patient-specific acetabular components.

Effective treatment of large acetabular defects remains among the most challenging aspects of revision total hip arthroplasty (THA), due to the deficiency of healthy bone stock and degradation of the support columns. Generic uncemented components, which are favored in primary THA, are often unsuitable in revision cases, where the bone-implant contact may be insufficient for fixation, without significant reaming of the limited residual bone. This study presents a computational design strategy for automatically generating patient-specific implants that simultaneously maximize the bone-implant contact area, and minimize bone reaming while ensuring insertability. These components can be manufactured using the same additive manufacturing methods as porous components and may reduce cost and operating-time, compared to existing patient-specific systems. This study compares the performance of implants generated via the proposed method to optimally fitted hemispherical implants, in terms of the achievable bone-implant contact surface, and the volume of reamed bone. Computer-simulated results based on the reconstruction of a set of 15 severe pelvic defects (Paprosky 2A-3B) suggest that the patient-specific components increase bone-implant contact by 63% (median: 63%; SD: 44%; 95% CI: 52.3%-74.0%; RMSD: 42%), and reduce the volume of reamed bone stock by 97% (median: 98%; SD: 4%; 95% CI: 95.9%-97.4%; RMSD: 3.7%).

Research on Attitude Analysis of Hydraulic Support Based on Column Length

The existing hydraulic support attitude monitoring and control methods integrate multiple sensing technologies, but it is difficult to apply and promote due to unclear monitoring mechanisms, complicated types, and a large number of sensors. Aiming at the problem of attitude monitoring and control of hydraulic support, firstly, the kinematics mathematical model of hydraulic support is established by the key marker point method and the two-dimensional bar system model, and the forward and inverse solution algorithm of hydraulic support attitude based on the double-drive length of front and rear columns is proposed. Secondly, the rigid body dynamics simulation model of hydraulic support is constructed to verify the theoretical analytical model and prove the correctness of the algorithm. The rigid body simulation model can be used as the attitude monitoring system of hydraulic support. Thirdly, considering the influence of material elastic deformation, a rigid-flexible coupling dynamic simulation model of hydraulic support is established to explore the influence of elastic deformation of components on the attitude of hydraulic support and its causes. On this basis, the rigid-flexible coupling dynamic simulation model of the hydraulic support with clearance is established by replacing the revolute pair in the simulation model with the solid axis pin connection unit. The influence of the axis pin connection clearance on the attitude of the hydraulic support and its causes are explored, and the actual attitude and change characteristics of the hydraulic support under simulated real conditions are obtained. Finally, considering the force compression of the hydraulic cylinder of the column, the rigid-flexible and machine-liquid coupling dynamic simulation model of the hydraulic support with clearance is constructed.

Theoretical prediction of soft-forming micro-hemispherical shells from fused silica substrates in reclining mold

A reclining mold can support the soft forming of fused silica substrates into micro-hemispherical shells with the same height, which makes the processing of micro-hemispherical shells attractive. Currently, it is difficult to determine the optimal process parameters for machining micro-hemispherical shells, and several iterations of experiments are required. This process wastes large amounts of substrate material, experimental consumables, and machining time, and increases the cost of the experiments. In this paper, we report a reflow process for soft-forming micro-hemispherical shells from fused silica substrates supported by a reclining mold. The shapes of the shells formed from the fused silica substrates in reclining and non-reclining molds were analysed by building a two-dimensional model. Moreover, we predicted the effects of varying the process parameters on the shell-forming time and geometrical parameters, as well as the stresses and deformations of the shells after cooling. The effect of the eccentricity of the central support column of the mold on the symmetry of micro-hemispherical shells was also investigated, and the influence of the mold and substrate heating inhomogeneity on micro-hemispherical shell formation was analysed. Additionally, the heat uniformity of the substrate in the rotating state was examined. Finally, we investigated the temperature field and thickness distribution during the shell-forming process through 3D modelling to verify the 2D modelling results. Analysing and predicting the parameters helps to reduce the number of trial-and-error processes in experiments, and we expect this work to provide a theoretical parametric basis for micro-hemispherical shell machining.

Study on the corrosion performance of supersonic atmospheric plasma sprayed Cr3C2-NiCr coatings

PurposeDue to the harsh underground environment in coal mining, the surface of hydraulic support columns corrodes severely, resulting in significant economic losses. Therefore, a highly corrosion-resistant coatings is needed to extend the service life of the columns.Design/methodology/approachThis study aims to compare the corrosion resistance of ST-Cr3C2-NiCr (sealed treatment Cr3C2-NiCr) coatings with industrially applied chromium plating. The corrosion failure mechanism of the coatings was investigated.FindingsThe results demonstrated that the ST-Cr3C2-NiCr coatings exhibited excellent corrosion resistance. After sealing treatment, the corrosion potential of Cr3C2-NiCr coatings was −0.215 V, and the corrosion current density of Cr3C2-NiCr coatings was lower than that of the plated parts.Practical implicationsST-Cr3C2-NiCr coatings prepared by supersonic atmospheric plasma spraying could provide excellent corrosion resistance in the coal industry.Originality/valueThe low porosity and the presence of the NiCr phase were crucial factors contributing to the preferable corrosion resistance exhibited by the ST-Cr3C2-NiCr coatings. The corrosive process of the coatings involved layer-by-layer delamination of surface oxide film, sub-surface pitting, formation and degradation of sub-surface passive film, as well as severe block-like delamination.

Experimental Investigation on Ultra-Thin Vapor Chamber with Composite Wick for Electronics Thermal Management.

Ultra-thin vapor chambers (UTVCs) are widely used to cool high-power electronics due to their excellent thermal conductivity. In this study, a UTVC of 82 mm × 58 mm × 0.39 mm with composite wick was prepared. The composite wick is composed of two layers of copper mesh and multiple spiral-woven meshes (SWMs), and the composite wick was applied in UTVC to improve liquid replenishment performance and temperature uniformity. Furthermore, the thermal performance of UTVCs with different support column diameters, filling ratios (FRs), and SWM structures was experimentally studied. The results found that the equivalent thermal conductivity (ETC) decreases as the diameter of the support column increases; the UTVC with 0.5 mm support column diameter has the highest ETC, at 3473 W/(m·K). Then, the effect of FR on the heat transfer performance of UTVCs with SWM numbers of 0, 1, 2, and 3 (0 SWMs, 1 SWM, 2 SWMs, 3 SWMs) is consistent, the 30% FR UTVC with 3 SWMs having the highest ETC, at 3837 W/(m·K). Finally, the increased number of SWMs can significantly improve the ultimate power of the UTVCs, the UTVC with 3 SWMs having the highest ultimate power, at 26 W. The above experimental studies indicate that the designed and manufactured UTVCs have great potential advantages in thermal dissipation for electronics.

Elevational Earth-Sheltered Buildings with Horizontal Overhang Photovoltaic-Integrated Panels—New Energy-Plus Building Concept in the Territory of Serbia

The global scientific community is intensively promoting energy-plus buildings. Following the leading world trends, this paper presents a new energy-plus building concept—elevational earth-sheltered buildings with three different types of horizontal overhang photovoltaic-integrated panels: wooden support columns covered with clay tiles, steel pipes as support columns covered with sheet steel, and concrete support columns with concrete coverage. In this instance, the specific multi-numerical case study building model for the city of Kragujevac (located in central Serbia with favorable climatic conditions) was performed over 7 months (from 1 October to 30 April), taking into account the soil temperature, the effects of solar shading, the performance of the heating system—a ground source heat pump—and the characteristics of the artificial and automatic lighting control system. The simulation results show that the optimal depth of a horizontal overhang (energy-plus status) depends on the occupant’s habits, in addition to meteorological conditions. The presented methodology can be used for any other location, both in Europe and the world.

Experimental and numerical study on the energy absorption performance of aluminum foam-filled multi-cell square tubes

When rockbursts occur, the unloading rate of the relief valve of the hydraulic support is less than the loading rate of the impact load, which leads to a continuous increase in the hydraulic column pressure or even failure. To improve the service life of hydraulic support structures under impact loading, an aluminum foam-filled multi-cell square tube is designed and investigated as an energy absorption component to prevent support column failure. In this study, the energy absorption performance of the multi-cell square tube during buckling deformation is investigated via simulation and quasi-static compression tests considering the cross-sectional shape and aluminum foam filling rate. The equivalent crushing load of the tube is calculated by analyzing the impact of the basic deformation unit. The results show that the corner-to-corner (C2C) multi-cell square tube exhibits the best energy absorption performance among six kinds of cross sections. In addition, the interaction between aluminum foam and a multi-cell square tube can improve the performance of the multi-cell square tube. Furthermore, after the C2C component is installed in the support column, the load on the column is significantly reduced, and most of the impact energy is absorbed. These results are expected to improve the performance of hydraulic supports and can be used to prevent rockbursts, which is highly important for practical engineering.

Numerical study on hydrodynamic characteristics of deep sea microfluidic eel energy capture device

Ocean current energy is a stable, reliable, and highly predictable renewable energy source. The effective development of ocean current energy conversion technology is beneficial in addressing the issue of power shortage. However, the majority of current velocities worldwide are below 1.5 m/s, limiting the feasibility of using conventional current energy capture devices. This paper presents a vortex induced vibration based deep sea microfluidic eel energy capture device (VIV-EEL) designed to efficiently harness energy in low-speed current environments. The system employs Computational Fluid Dynamics (CFD) to develop a series of computational models that couple underwater multibody fluid-solid interactions. These models are subsequently validated through experiments. The study analyzed the flow field of VIV-EEL under different working conditions and discussed the impact of several dimensional parameters of the elastically supported cylinders, structural parameters of raft plates, and flow velocity on the hydrodynamic performance. The results demonstrate that the energy capture efficiency of VIV-EEL is enhanced by the vorticity vibration effect. It is evident that there exists an optimal radius size for the elastic support column to achieve the most favorable resonance effect in the flow field of VIV-EEL. The energy capture characteristics of the raft plate show a linear relationship with its structural parameters, enabling quantitative design according to the requirements of the power take-off system (PTO). Moreover, VIV-EEL exhibits a lower start-up flow velocity compared to traditional current energy capture devices, enabling it to initiate and capture energy at a flow rate of 0.3 m/s. This innovative solution offers technical support for efficient low-speed current energy capture.

Behavior of Metal Frame of Ribbed-ring Dome with Decrease in Number of Supporting Columns

Investigation of the stress state of the metal frame of a ribbed-ring dome, when the number of supporting columns under it is gradually reduced. With that, the same distances or steps between the columns are maintained along the entire contour of the support ring. The main elements of the dome frame and columns are made of steel I-beams. Frames, the domes of which are supported by a different number of cyclically symmetrical columns, were considered as subjects of research. All the domes are characterized by the same geometric structure and size, the same cross sections of the same type of frame elements and are exposed to the same loads. The research was carried out on computer models by calculating the combined effect of the load from the weight of load-bearing and enclosing structures and an asymmetric snow load. The models with a reduced number of columns are obtained by regularly removing them from the original computer model. During the analysis, the stresses in the elements of the frames of all models were determined, which were compared with each other. Deformation graphs and comparative diagrams of the stress state relationships of the frame elements of the original and transformed models are obtained. An assessment of the change in the stress state of the ribbed-ring dome frame with a decrease in the number of columns is given. Significant changes in the stress state of the support ring were noted.

Prediction Method for High-Speed Laser Cladding Coating Quality Based on Random Forest and AdaBoost Regression Analysis.

The initial melting quality of a high-speed laser cladding layer has an important impact on its post-treatment and practical application. In this study, based on the repair of hydraulic support columns of coal mining machines, the influence of high-speed laser cladding process parameters on the quality of Fe-Cr-Ni alloy coatings was investigated to realize the accurate prediction of coating quality. The Taguchi orthogonal method was used to design the L25(56) test. The prediction models of the relationship between the cladding process and the coating quality were established using the Random Forest (RF) and AdaBoost (Adaptive Boosting, AB) algorithms, respectively. Then, the prediction accuracy of the two models was compared, and the process parameter features were screened for importance evaluation. The results show that the AB prediction model is more accurate than the RF prediction model and more sensitive to abnormal data. The importance evaluation based on the AdaBoost model shows that the scanning speed has a great influence on the height and surface roughness of the coating. On the other hand, the overlap rate is the most important factor in controlling the dilution ratio and near-surface grain size of high-speed laser melting coatings. In addition, the micro-hardness of the coating and the thermal effect of the substrate can be effectively enhanced by adjusting the laser power and scanning speed. Finally, it was verified that the AB prediction model could accurately estimate the quality indexes of the coating with a prediction error less than 6%. The results show that it is feasible to predict the quality of high-speed laser cladding with the AB algorithm. It provides a basis for the adjustment of process parameters in the subsequent quality control process of cladding.

Experimental study on ultra-thin silicon-based VC for chip-level heat dissipation

The trend towards miniaturization and integration of integrated circuits has led to the emergence of local hotspots with high heat flux and high temperature frequently. Integrating vapor chamber (VC) directly on the surface of semiconductor electronic devices, can effectively address the problem of overheating on the chip surface, and is therefore considered as a promising thermal management solution. However, the challenge of reducing the size of the VC while improving its heat transfer performance cannot be ignored. To address this, a silicon-based VC with thickness of 0.6 mm is designed and fabricated in this study. Structural optimization is carried out, including the design of three types of wicks using square micropillar arrays and two types of support columns including solid and porous and an experimental system is built to study the influence of these structures on the heat transfer performance of VC. The results indicate that the VC can still function normally under the highest heat flux of 123.6 W/cm2, resulting in lowest thermal resistance of 1.54 °C/W. For wicks, the thermal resistance of VC with characteristic size of 10 μm is reduced compared with that of 20 μm. The introduction of gradient wick, that is, using small-size (10 μm) micropillar arrays in heating area and big-size (20 μm) micropillar arrays in non-heating area, can effectively reduce the thermal resistance of VC. Moreover, the solid support columns are found being advantageous in reducing the thermal resistance of VC, while porous support columns improve the surface temperature uniformity of VC. This work provides a feasible path to optimize silicon-based VC.

Influence of the Elastic-Plastic Dynamic Artificial Boundary on the Progressive Collapse Performance of Truss Structures

The traditional fixed boundary could not transmit the elastic-plastic stress waves in the progressive collapse analysis of the truss structures, leading to discrepancies in understanding the true response of structures. To solve the critical problem, a new dynamic artificial boundary is proposed and integrated into the truss structure to transmit elastic-plastic stress waves. The new dynamic artificial boundary is established through the integration of the elastic-plastic constitutive model into the governing equation of the stress wave. This boundary is subsequently implemented within the ABAQUS finite element software for the purpose of conducting progressive collapse analysis of the truss structures. The progressive collapse simulation of the truss structures involves a comparative analysis between the new dynamic artificial boundary and the traditional fixed boundary. Numerical analysis demonstrates that the dynamic artificial boundary led to varied initial failure and collapse compared to the fixed boundary. The failure typically occurs at the mid-span under the dynamic boundary. In contrast, additional failures occur near the support columns under the fixed boundary due to stress wave reflections. The dynamic artificial boundary more closely reflects the physical reality and provides a new method for the progressive collapse analysis of the truss structures in practical applications.

Ultrahigh-sensitivity fiber-tip microcavity ultrasonic sensor based on optomechanical effect

An ultrahigh-sensitivity fiber-tip cavity ultrasonic sensor based on optomechanical effect fabricated by Two-photon Polymerization (TPP) Technology is presented. The microcavity is based on all-polymer material with the structure of three support columns and two micro-discs, and one micro-disc with one round hole. Experiment results show that the sensor has an ultrahigh sensitivity which is 889 times as big as that of the commercial acoustic sensor. It has a good frequency response within the frequency range of 52.19 KHz-384.6 KHz. The sensor exhibits the inherent advantages of small size, compact structure, easy of fabrication, high sensitivity and wide band acoustic response, and is expected to have application in ultrasonic sensing and imaging.

Structural integrity analysis of the pre-stressed concrete dome of the Belgrade fair hall 1

Belgrade fair hall 1 is well known for its dome, which is still the world largest self-supported construction made of pre-stressed concrete, with its diameter of 106 m. In this paper the Finite Element Method (FEM) was performed to analyze different loading and supporting conditions. At the same time, crack growth in a support column was simulated by the extended FEM (XFEM). Results of numerical calculations indicate ingenious design of such a complex structure which was based on “hand” calculation decades ago, without computers. In addition to classical engineering and more advanced numerical calculations, risk based analysis was performed taking into account artificially introduced crack and Failure Analysis Diagram, obtained using stress intensity factor and net stress, as well as fracture toughness and critical stress. This analysis, made for the first time for Belgrade fair hall 1, proved that its structural integrity is jeopardized only when a crack reaches half the thickness of a steel bar.

Design and Application of New Support and Power System of Residential Building Machine

In recent years, with the transformation and upgrading of national development and the acceleration of urbanization, the construction mode of high energy consumption, high pollution and high labor intensity in the construction industry can no longer meet the development needs. The State Council and the Ministry of Housing and Urban-Rural Development have successfully issued policies and initiatives to improve industrialization and intelligent construction. In 2021, the Ministry of Housing and Urban-Rural Development issued a building height limit order, and it has become a trend that aerial building machines have begun to diversify into ordinary high-rise residences. The "14th Five-Year Plan" construction industry development plan issued by the Ministry of Housing and Urban-Rural Development proposed accelerating the coordinated development of intelligent construction and new building industrialization and promoting digital design, intelligent production and intelligent construction. In response to the national policy guidance and leading the development of the industry, solve the inherent problems in the construction industry, learn from the application concept of super high-rise heavy-duty construction equipment integration, create a "factory-like" construction environment for ordinary high-rise through lightweight, standardization and intelligent and other innovative technologies, and explore a construction integration platform suitable for high-rise residences, called "high-rise building industrialization construction lightweight construction operation integration platform" (referred to as "building machine"). Based on the first generation of building construction machines, continuous improvement and replacement, the supporting power system has dramatically improved in support capacity and lightweight. The effective combination of a support column, hydraulic cylinder, and pump station has been realized, which is more convenient and faster, and the construction is more efficient.

Physical and mechanical properties of foamed concrete, a literature review

Foamed concrete is distinguished from regular concrete's lightweight, high strength-to-weight ratio, and exceptional rheological and thermally insulating qualities. Foamed concrete offers reduced manufacturing and shipping costs than conventional concrete and can be used for structural components. Reduced energy consumption and self-weight of the superstructure are achieved by using foamed concrete. This article provides a comprehensive look into the mechanical, functional, and physical characteristics of foam concrete and the materials and processes involved in their production. This quantitative literature review had two main goals: (1) to pinpoint research gaps and (2) to give readers a comprehensive grasp of the many ways in which certain cell types might be put to use. Since it is both lightweight and durable, foamed concrete is a great material. Foamed concrete is employed because it reduces the foundation and support columns' load, saving energy, time, and money. As a possible structural material, it offers savings in producing and transporting construction components over traditional concrete. This paper describes the qualities, building procedures, and materials that go into making foamed concrete. This critical review aims to introduce readers to foamed concrete and its potential uses in the modern building sector. Foamed concrete's strength and density can be affected by a number of factors, including the mix proportions used, the foam agent quality and quantity, and the manufacturing technique. Fly ash, silica fumes, plastiziers can be used to increase its compressive strength.