Panel Length Research Articles

Influence of mining depth and panel length in longwall underground coal mining on the distribution of principal stresses along the barrier pillars

Abstract The production increase in longwall underground coal mining is in line with the dimension changes of the mining panel that subsequently affect changes in stress distribution and disrupts roadway stability. This paper studies the effect of panel dimensions on stress distribution around the roadway using the finite element method to model the panel conditions numerically, drawing height and shape of the goaf from empirical data. In this study, the length of the panels made varied between 500 and 1500 meters and the depth of the panels varied between 200 and 1000 meters from the surface. Based on the modelling results, stress changes due to differences in panel size occurred at the depth of 800 and 1000 meters, the longer the panel, the greater the stress that occurs. The further from the surface, the greater the pressure on the barrier pillar, at a depth of 200 meters the main pressure is 3.4 times the vertical pressure at the end of the excavation, while at a depth of 1000 meters the pressure increases to 5 times the vertical pressure.

Energy-Saving Potential of Building-Integrated Photovoltaic Technology Applied to a Library in Changsha, China

With the increasing number of public buildings worldwide, their energy consumption has garnered significant attention. This study aims to promote building energy efficiency and emission reduction by exploring the application of Building-Integrated Photovoltaic technology in library retrofitting. Using a library in Changsha City as a case study, we conducted an energy consumption analysis of the building’s envelope and identified the window section as the highest energy consumer. We proposed a novel improvement scheme—the sun-shading photovoltaic panel (which shades the sun while generating electricity). Additionally, we utilized the roof space for the installation of conventional photovoltaic panels. Simultaneously, the primary objective of this paper was to derive a renovation strategy for public buildings in regions characterized by high summer temperatures and low winter temperatures based on the renovation case of this library. This paper comprehensively investigates the length and angle of sun-shading photovoltaic panels facing different directions, as well as the azimuth angle, tilt angle, and installation spacing of the conventional photovoltaic panels on the roof. Two retrofitting schemes were proposed. Through simulation and comparison, the second scheme was found to reduce the annual electricity consumption by 1,233,354 kWh, achieving a 35.4% decrease compared to the original building. Using the Changsha library as a template for public buildings, this study provided a retrofitting approach with Building-Integrated Photovoltaic technology via DesignBuilder, which could be extended to other geographic locations. The results demonstrated the significant energy-saving effects of the proposed retrofitting scheme.

RESEARCH OF THE DESTRUCTION CONDITIONS OF GLAZING OF ENCLOSING STRUCTURES UNDER THE CONDITIONS OF THERMAL INFLUENCE OF FIRE

The article presents the main results of mathematical modelling of the destruction of glazing of enclosing building structures with translucent elements under fire conditions. The authors analyse literature data on calculating the fire resistance of enclosing building structures with glazing. The results show that improving methods for predicting the fire resistance of glazing is relevant. Mathematical models for the numerical study of the behaviour of glazing under the thermal influence of the standard fire temperature regime are substantiated. Mathematical models of the heat transfer process involve using a non-stationary differential equation of heat conduction with boundary conditions of the third kind, accounting for the convective and radiant heat exchange between the air in the room with the fire and the glazing. As a criterion for the destruction of glazing under the influence of fire, the authors establish the temperature resistance parameter, which is determined based on the mechanical characteristics of the glass. The article highlights the relevant data on the study of temperature indicators and the mechanism of glazing failure, using mathematical modelling with well-founded mathematical models. It obtains the results of the thermal calculation by applying the finite difference method for solving the non-stationary differential equation of thermal conductivity. The methodology for determining the time of glazing failure under the influence of the standard temperature regime of a fire using the calculation parameters obtained based on well-founded mathematical models is substantiated. An analysis of the adequacy of the obtained calculation data was carried out by comparing them with the results of experimental studies using statistical criteria. As a result of the analysis, the authors confirmed the validity of the calculation data. A complete factorial experiment was conducted based on well-founded mathematical models, which revealed the regularities of the dependence of the parameters of thermomechanical processes in single-layer glass on its structural characteristics. The revealed regularities have the form of linear regression dependences of the destruction time on the thickness of the glazing and the maximum length of the glass panel without bars. Using the regularities of the dependence of the parameters of thermomechanical processes in single-layer glazing on its structural characteristics, the authors constructed reference tables for evaluating the fire resistance of enclosing structures with glazing. The research obtained new scientific data on the study of the behaviour of glazing of enclosing building structures under the thermal influence of fire through mathematical modelling, which is the basis for improving the methods of calculating the fire resistance of enclosing structures with translucent elements. Keywords: enclosing building structures, glazing, fire resistance limit, calculation method, glass heat resistance.

Fluid–Structure Interactions between Oblique Shock Trains and Thin-Walled Structures in Isolators

Understanding aeroelastic issues related to isolators is pivotal for the structural design and flow control of scramjets. However, research on fluid–structure interactions (FSIs) between thin-walled structures and the isolator flow remains limited. This study delves into the FSIs between thin-walled panels and the isolator flow, as characterized by an oblique shock train, by quantitatively analyzing 11 flow parameters assessing the structural response, separation zones, shock structures, flow symmetry, and performance. The results reveal that an FSI triggers panel flutter under oblique shock train conditions, with the panel shapes exhibiting a combination of first- and second-mode responses, peaking at 0.75 of the panel length. Compared to rigid wall conditions, isolators with a flexible panel at the bottom wall experience downstream movement of the separation zones and shock structures, reduced flow symmetry, and minor changes in performance. Transient fluctuations occur due to the panel flutter. Two flexible panels at the top and bottom walls have a comparatively lesser influence on the averaged parameters but exhibit more violent transient fluctuations. Furthermore, the FSI effects under oblique shock train conditions are contrasted with those under normal shock train conditions. The flutter response under normal shock train conditions is more pronounced, with a larger amplitude and higher frequency, driven by the heightened participation of the first-mode response. The effects of FSIs under normal shock train conditions on the averaged parameters are the opposite (with a larger influence) to those under oblique shock train conditions, with significantly more drastic transient fluctuations. Overall, this study sheds light on the complex and substantial influence of FSIs on the isolator flow, emphasizing the necessity of considering FSIs in future isolator design and development endeavors.

Ultimate strength of welded aluminium stiffened panels under combined biaxial and lateral loads: A numerical investigation

The number and size of aluminium non-monohull ships have been steadily increasing over time. This raises growing concerns regarding their structural strength, especially considering the adverse effects of the heat-affected-zone (HAZ) on welding connections in aluminium structures. This paper investigates the ultimate strength of welded aluminium stiffened panels under combined biaxial compressive loads and lateral pressure through the application of numerical simulations. Altogether 360 cases are simulated with varied panel lengths, welding patterns and load combinations. The results are presented and discussed with respect to force end-shortening curves, failure modes and ultimate strength. Influences of the combined loads and HAZ effects are summarized. The numerical results are compared to two commonly used design methods in the marine industry, the International Association of Classification Societies (IACS) rule and the Panel Ultimate Limit States (PULS) approach. Their applicability to welded aluminium stiffened panels is discussed, and modifications are suggested with respect to the transverse loads, lateral pressure, and HAZ effects.

A Study on the Effects of Welding Deformation According to Weld Sequence in Overlay-Welded Structures

In this study, thermal elasto-plastic finite element analysis was conducted to derive the optimal welding sequence to minimize overlay welding deformation on the water wall panels of an SRF (solid refuse fuel) boiler. The water wall panels of an SRF boiler are exposed to high temperatures and corrosive environments, making overlay welding essential. However, because the length of the water wall panels and tubes exceeds 7 m, significant deformation occurs after overlay welding. Additionally, due to the large size of the water wall panels, full-size thermal elasto-plastic analysis requires huge computational costs. Therefore, in this study, the effects of welding sequence on overlay welding deformation were first investigated for a reduced model to derive the optimal welding sequence. Subsequently, an analysis model for the full-size pipe panels was established to compare and analyze the conventional welding sequence with the optimal welding sequence, thereby verifying the validity of the study. According to the welding sequence derived from the reduced model, welding deformation in the full-size model was significantly reduced compared to the conventional sequence. This reduction in deformation was discussed by analyzing the deformation behavior of the structure at each stage of the overlay welding process.

Numerical parametric study of cross-laminated timber diaphragms under in-plane loading

Cross-Laminated Timber (CLT) is a mass timber product that has gained recognition as a viable structural product for tall and large structures. While CLT provides several advantages, such as being eco-friendly, lightweight, and improving thermal insulation compared to other primary structural materials, its application in the horizontal diaphragms, specifically for floors and roofs, has not been thoroughly investigated. This paper presents the development of a detailed finite element (FE) model capable of simulating the response of CLT diaphragms under in-plane loading. The accuracy of the developed models was evaluated through comparison with available experimental data. Additionally, a comprehensive parametric study was conducted to examine the influence of various factors, including connection stiffness, boundary condition, panel installation pattern, and panel thickness, on the in-plane deflection of the CLT diaphragm. The research indicates that panel-to-panel connections play a more critical role in determining the stiffness of CLT structures than panel-to-beam connections. Furthermore, it was demonstrated that the deflection of CLT panels was influenced by different parameters depending on the orientation of the applied load. When the load is applied perpendicular to the panel length, panel thickness influences the diaphragm deformation. Conversely, when the load is applied parallel to the panel length, the panel-to-panel connection stiffness has a more significant effect on the deformation of the diaphragm. Findings also revealed that staggered CLT panel layouts provided more load distribution and higher capacity compared to non-staggered layouts when the load was applied perpendicular to the panel length.

Effect of Screen-Panel Tensile Length and Material Characteristics on Screening Performance of Flip-Flow Vibrating Screens for Dry-Screening Fine, Low-Grade Bituminous Coal

Flip-flow vibrating screens (FFVSs) effectively tackle the challenges posed by the dry deep-screening of wet, fine, low-grade bituminous coal, thereby facilitating advancements in the thermal coal preparation process. The tensile lengths of the screen panels not only influence the service lives of the screen panels but also play a pivotal role in determining the screening performance of the FFVSs. To investigate the effect of the screen-panel tensile length on the screening performance of an FFVS, this study constructs a dual-mass flip-flow screening test rig. The experimental results reveal that when the fine-particle content and the external water content in the feed of low-grade bituminous coal are 55% and 16%, respectively, the most favorable tensile length of the screen panels is 2 mm. With a fine-particle content of 55% in the feed of low-grade bituminous coal and an increase in the external water content from 4% to 20%, the screening efficiency of the FFVS initially decreases and then increases. Notably, low-grade bituminous coal with 16% external water content poses the most challenging screening conditions. Furthermore, when the external water content of the low-grade bituminous coal is 16% and the fine-particle content in the feed increases from 25% to 55%, the screening efficiency of the FFVS gradually improves.

Fishes of the Alitash National Park: Taxonomic Accounts with Identification Keys of Fish in Floodplain Rivers of Abbay and Tekeze Basins, Ethiopia

Ethiopia has considerable freshwater potential. Currently, the recognized fish diversity in the country’s freshwater ecosystem is more than 200. Despite the presence of such high fish diversity with considerable economic returns, ichthyofaunal studies on Ethiopian rivers are scarce. Thus, this study aimed to identify and compare ichthyofaunal diversity and distribution in floodplain rivers of the Abbay and Tekeze Basins, Ethiopia. Fish were collected using gillnets, cast nets, hooks, electrofishing, and mosquito nets and identified to the species level. Gillnets had stretched mesh sizes of 4–14 cm with a panel length of 25–75 m and a width of 1.5–2 m per mesh size. They were set in the afternoon (5:00 p.m.) and lifted the following morning (7:30 a.m.). Immediately after capture, fish were preliminary identified in the field and tagged with proper information (e.g., sampling locality and date of collection). Similar fishing efforts were applied at all sampling sites for two dry and two wet months over a period of two years (2018-2019). In the present study, both alpha and beta diversity indices were also examined. Identification keys and an annotated checklist of species were generated for easy naming of the entire fish species in the basins. In the ichthyological collection, 43 fish species with 11 new records from the Ayima, Gelegu, and Shinfa Rivers were identified. The first two rivers in the Abbay Basin were the richest in species and number of individuals. Gelegu River had the highest abundance as well. Generally, this study was conducted in areas where no fish biodiversity studies have been undertaken, and the results obtained from this study could be important for fish biodiversity conservation.

Measurement of noncooperative spacecraft components using multistatic spaceborne radar and optical images

Attitude and size estimation of spacecraft components is one of the main contents of space target awareness. In this paper, a radar-camera joint observation scheme applicable to multiple spaceborne platforms is developed to measure the orientation and length of the spacecraft solar panels, which benefits from the observation diversity jointly provided by radars and cameras. Firstly, an automatic keypoint detection network is trained to extract the endpoints of the solar panels in the radar and optical images with high accuracy. Then, the projected lengths of the solar panels calculated from the extracted endpoints along with the observation equations of the radars and cameras are jointly used to obtain the orientation and actual length of the solar panels by an optimization approach. Simulated experiments are conducted to demonstrate the performance of the proposed measuring methods, which achieves length estimation errors within 0.2 m and orientation estimation errors within 1°. The proposed method can be extended to the measurement of main body and other spacecraft components having regular features.

Multi-objective optimization for snap-through response of spherical shell panels

Composite spherical shell panels are commonly used for the lightweight design of thin-walled structures in the structure, architecture, aerospace engineering. Depending on the shell panel length, thickness, curvature, and stacking sequence, the load-deflection response under lateral load can be either a completely stable equilibrium path or an unstable snap-through path. In this work, the response of simply supported cross-ply composite spherical shell panels subjected to lateral static loads is studied and optimized. The spherical shell exhibiting snap-through response is optimized to (a) maximize the load required to initiate snap-through and (b) minimize the unstable region. Meanwhile, the spherical shell exhibiting continuous response is optimized to (a) maximize the softening-hardening load and (b) minimize the shell weight. The decision variables for both constraint multi-objective optimization (CMOO) problems include layup sequence, thickness, and the radius of curvature to side length ratio. The nonlinear governing equations are derived based on Kirchhoff–Love hypotheses for thin shells and Hamilton's principle. A novel semi-analytical method is presented based on Bernstein polynomials combined with a fast iterative approach to compute the objective features of the responses. Benefiting from the high efficiency and robustness of the proposed approach, the CMOO problems are solved by the metaheuristic Multi-Objective Artificial Hummingbird Algorithm (MOAHA). Composite spherical shell panels with various geometry and lamination configurations are considered to validate the performance of the proposed method. The optimization of geometric parameters (shell curvature and thickness) in addition to the staking sequence provide a high degree of tailoring of the shell performance to meet various objectives. These parameters are taken as design variables that must be optimized to achieve some objectives and satisfy arbitrary nonlinear constraints.

Establishment and applicability verification of hysteretic model of shear wall bottom corner dampers

In this study, the experimental results of a shear wall bottom corner damper (SWBCD) were investigated. It was found that the effects of the corrugated shear panel thickness, corrugated shear panel length, and flange plate thickness on the seismic performance from large to small. The failure process of the specimens was summarized; it was found that the high stiffness at the bend contributed to failure of cross-cracks in each long corrugated band of the corrugated shear panel in all specimens due to the geometric shape constraints of the corrugated shear panel. According to the calculation method for the skeleton curve parameters and the hysteretic rules of the SWBCD, a multilinear hysteretic model of the SWBCD was established. Using a corrugated steel plate-reinforced concrete composite shear wall with bottom corner dampers (RSPCW) as the application background, based on the layer shell model, a reasonable equivalent simulation method for an embedded corrugated steel plate based on the tension strip model was proposed. The hysteretic model of the SWBCD was modified according to the deformation requirements of the bottom corner damper. The twoNodeLink element representing the SWBCD was placed in the height range under the boundary element at both ends of the RSPCW. The ability of the hysteretic model to accurately reflect the nonlinear analysis of the SWBCD was verified.

The Capstone Design of Solar Farm for Alternative Energy

The capstone design integrates advanced technologies to optimize energy capture, storage, and transmission, addressing key challenges in traditional solar farm configurations. The study delves into the conceptualization, engineering, and performance evaluation of the proposed solar farm, emphasizing its potential for enhanced efficiency and sustainability. Additionally, the article discusses the environmental impact and economic viability of the free space solar farm, highlighting its role in advancing the transition to a more sustainable and resilient energy infrastructure. The results of this design use polycrystal type solar panels with a panel length of 1995mm and a width of 990mm which will be installed on empty land that has been provided with a land area of 80m x 40m, 50 rows of solar panels are obtained and the total energy produced before being converted into KWP with a total of 50 rows of panels is obtained 325 WP and multiplied by the total existing panels, namely 36 solar panels, the result is 11,700 WP, then converted to KWP and the result is 585 KWP for 1 day. The findings contribute valuable insights to the field of renewable energy engineering, offering a comprehensive understanding of the practical application of free space for solar energy generation.

A 2-dimensional guillotine cutting stock problem with variable-sized stock for the honeycomb cardboard industry

This paper introduces novel mathematical optimisation models for the 2-Dimensional guillotine Cutting Stock Problem with Variable-Sized Stock that appears in a Spanish company in the honeycomb cardboard industry. This problem mainly differs from the classical cutting stock problems in the stock, which is considered variable-sized, i.e. we have to decide the panel dimensions, width, and length. This approach is helpful in industries where the stock is produced simultaneously with the cutting process. The stock is then cut into smaller rectangular pieces that must meet the customers' requirements, such as the type of item, dimensions, demands, and technical specifications. Furthermore, in the problem tackled in this paper, the cuts are guillotine, performed side to side. The proposed mathematical models are validated using real data from the company, obtaining results that drastically reduce the produced material and leftovers, reducing operation times and economic costs.

Experimental and analytical evaluation of the tension capacity of edgewise connected glued-in rods in mass ply panels

The length of mass timber wall panels is a limiting factor in designing taller buildings. Splice designs are needed to maintain panel transportability while transferring shear and moment forces from higher floors to the foundation under lateral loading. One such splice design utilizes structural adhesive to glue threaded steel rods into the ends of wall panels being connected. This paper reports tests of the tension capacity of glued-in rods embedded in Mass Ply Panels (MPP). Twenty glued-in rods were tested under monotonic and cyclic protocols. Embedment depths ranged between 304.8 mm (12 in.) and 812.8 mm (32 in.). Load and displacement were measured during tests to report values per ISO 6891 and an international code council acceptance criteria document. Elastic stiffness, peak capacity, design capacity, and a predictive capacity equation were determined. Results showed a similar stiffness for all embedment depths and a negligible difference between peak capacities from monotonic and cyclic testing. While the data reported is only directly applicable for analysis of the specific MPP and epoxy combination used in the test program, the methodology herein can be utilized for future testing of timber-adhesive glued-in rods.

Structural Behavior of Water Flow Glazing: Stress and Elastic Deformation Considering Hydrostatic Pressure

The fluid inside a Water Flow Glazing (WFG) panel creates a linear pressure distribution along the vertical dimension. Tension stress can cause problems with the sealant; compression stress can cause deflections in the glass panel. Increasing the glass thickness until the deflection is below the required limit implies more weight and cost of the glazing. Another solution is to limit glass deflection by inserting pillars or stripes into the cavity between two glass panes. The novelty of this article was to test a High-Order Finite Difference Method for linear and non-linear models to evaluate the effect of hydrostatic pressure produced by the fluid chamber on WFG panels. The methodology was tested on two case studies to assess the tension and deflection of the glass panes to guarantee the structural stability of WFG. The main conclusion drawn was that a linear plate model was sufficient to dimension the width, length, and thickness of the WFG panel. Furthermore, the mathematical model provided criteria to keep the glass tension below 45 MPa for tempered glass and the maximum deflection as the minimum between 1‰ of the glass height and 10% of the water chamber thickness. Introducing pillars or stripes solved hydrostatic pressure problems when the panel’s height was above 1.5 m.

Control of acoustic scattering of trailing edge flow by distributed compliance

In this paper, an approach for the reduction of trailing edge noise due to flow scattering from a semi-infinite splitter plate is proposed. It utilizes the fluid–structure interactions of well-designed multiple compliant elastic panels to suppress the flow instabilities within the boundary layers over the splitter plate to reduce overall trailing edge noise scattering. The approach is studied numerically using high-fidelity direct aeroacoustic simulation at low Reynolds numbers based on a panel length of 5×104. The noise reduction efficacy of the approach is analyzed by studying two different cases, and their underlying physical mechanisms are explored. First, the boundary layer over one side of the plate is subjected to a weak monochromatic acoustic excitation to produce laminar instabilities. Second, the boundary layer is subjected to a weak broadband excitation within the boundary layer. For each case, the panel system is uniquely designed with thorough consideration of the flow characteristics of the boundary layer instabilities of the problem. Comprehensive aeroacoustic analyses reveal that a significant sound power level reduction of 4.2 and 7.4 dB can be achieved by designed configurations for both kinds of excitation without any drag penalty. Nonlinear fluid–structure interactions of carefully designed elastic panels result in a weak correlation between the near-field flow instabilities and far-field noise. The flow-induced panel structural resonance is proven to effectively absorb the energy of boundary layer instabilities and their scattering at the trailing edge. Key characteristics for the design of compliance systems under different flow conditions are discerned and discussed.

Proposal of a microchannel receiver for Fresnel technology to supply solar heat for industrial processes

This work is focused on the linear Fresnel technology to supply solar heat for industrial processes, proposing a new microchannel receiver design for pressurised gases. This design consists of two absorber panels converging at the focal line of the Fresnel system; each of these panels consists of a compact core fin structure attached to both front and back plates. The fluid flows through the receiver along its length in several passes, so that the compactness is constant and greater than in the previous pass. This arrangement improves heat transfer and, therefore, the cooling of the more thermally stressed areas of the panel, without over penalising the pressure drop.A thermal resistance model has been formulated to quantify the fluid heating along the panel length and the thermal gradient along the panel thickness. This model has been used to perform a thermo-exergy optimisation based on several characteristic parameters: the aperture half-angle of the cavity shaped by the two converging panels; and the channels dimensions in each pass of the panel. For each of these parameters, a maximum exergy efficiency has been obtained accounting for the receiver heat losses, the fluid pressure drop and the optical performance of the primary mirror field.

Understanding Peanuts and Schulzian Symmetry: Panel Detection, Caption Detection, and Gag Panels in 17,897 Comic Strips Through Distant Viewing.

In this article, we applied distant viewing to a corpus of 17,897 comic strips from Charles Schulz’s Peanuts as a primary case study. Distant viewing uses computational techniques to study large-scale visual media, and draws upon interdisciplinary areas including visual media studies, cultural studies, data science, and semiotics. We focus on comic strips, particularly Peanuts, due to their widespread readership, historical and cultural cache, and complexity as a medium built on the interplay between text, image, and meaning. First, we discuss previous work done at the intersections of comics studies and computer vision. Next, we establish the processes for applying computer vision to comic strips. After that, we provide several examples, including: panel detection (variations in panel length over a cartoonist’s career); caption detection (identification and location of captions in panels); and comics paratext (computer vision analyses/exclusions of copyright text, signatures, dates, etc.). Combined studies of panel detection, caption detection, and comics paratext reveals new insights into the success, longevity, and influence of one of the world’s most famous newspaper comic strips. Ultimately, computer vision reveals a subtle stability and symmetry to Schulz’s artistry that played an understudied but significant role in the comic strip’s popularity.

Correlation of supersonic wind tunnel measurements with a nonlinear aeroelastic theoretical/computational model of a thin plate

Supersonic wind tunnel test data is compared with a nonlinear aeroelastic computational model, considering a freestream flow with Mach nearly 2, coupled cavity, and no-shock impingement. The measurements include Limit Cycle Oscillations (LCO) for the given set of flow and structural parameters. The effect of a static pressure differential, temperature differential, and the type of LCO is also studied: periodic or chaotic. A fully coupled aero-thermal–acoustic–elastic analysis was carried out, where the strong dependency of the dynamic instability upon the in-plane boundary stiffness was discovered. Associated with aerodynamic and acoustic formulations, the nonlinearities from the structure are found to be the strongest factor determining the occurrence and character of LCO. At the same time, the cavity effect was found to be negligible for this experimental configuration. Additionally, a comparison analysis was performed on the aerodynamic model for this flow condition between the Linear Piston Theory and the Full Potential Aerodynamics. The calculation of the critical flutter boundary was also performed in terms of the static pressure differential between the cavity pressure and the panel surface pressure, presenting regions where the panel is in static deformation due to the pressure differential versus LCO response. The comparison with the analytical model showed good agreement with the measured data, achieving a similar panel displacement at three-quarters of the panel length as well as the expected behavior of periodicity or chaos for specific values of temperature and static pressure differential.