Opening Size Research Articles

Experimental Investigation of Hydraulic Characteristics for Open Channel Gates

As irrigation districts rapidly advance in terms of informatization, research on intelligent water quantity control technologies for open channels has gained increasing importance. This study aims to investigate the flow capacity and hydraulic characteristics of gates in open channels, focusing on the flow measurement and the hydraulic behavior around water-measuring structures. Although automated control in irrigation systems has achieved significant development, research on the flow characteristics near gates remains limited. To address this gap, an integrated approach combining indoor physical model experiments with theoretical analysis was used. This study explored the water surface profile, cross-sectional flow velocity distribution, vertical velocity distribution, and turbulent kinetic energy under various gate opening conditions and flow rates. The findings reveal that the water surface exhibits a sharp rise upstream of the gate, followed by a steep decline and stabilization downstream, influenced by the gate’s water-blocking effect. The flow velocities near the gate opening differ significantly in direction and magnitude from those in other cross-sections, affecting both longitudinal and vertical velocities. The turbulent kinetic energy is concentrated near the gate opening, and the turbulent kinetic energy is primarily concentrated near the sidewalls and the channel bottom; the gate’s opening size plays a crucial role in its diffusion and distribution. Linear regression analysis was utilized to fit the gate flow coefficient formula, and a comparative analysis of the measurement accuracy was conducted. The relative error between the calculated flow values and the actual measured values is within ±5%, which meets the precision requirements specified in the water measurement standards for irrigation canal systems in the irrigation district. This study pioneers an integrated approach for investigating the hydraulic characteristics of gates in open channels, merging physical model experiments with theoretical analysis. It provides novel insights into how gate openings affect water surface profiles, flow velocity distributions, and turbulent kinetic energy. This research also underscores the role of gate discharge in turbulent kinetic energy distribution, offering technical insights to enhance flow measurement accuracy and prevent sediment deposition, thereby optimizing gate applications for efficient water management. Overall, this study significantly advances the understanding of open channel flow dynamics and holds substantial significance for the refinement of water quantity control techniques in irrigation districts.

Parameter Analysis of Resilient Precast Concrete Beam–Column Joints

Conventional precast structures often face the challenge of post-earthquake repair, especially at beam–column joints. A new type of precast concrete beam–column joint with a replaceable energy dissipation device consisting of cross-shaped and H-shaped steel was proposed in this paper, which was characterized by the use of replaceable energy-dissipating devices to improve the seismic capacity. Based on the previous test results of the group, this paper used ABAQUS to investigate how factors like the thickness of the H-shaped steel webs and the size and number of openings affected the seismic performance of precast concrete beam–column joints with replaceable energy dissipation devices. The results showed that (1) an increase in the H-shaped steel’s thickness in the REDDC could improve the load-carrying capacity of the node, but the energy dissipation capacity was weakened, and (2) the length and width of the H-shaped steel openings had almost no effect on the ultimate load-carrying capacity within a certain range, but increasing the size of the openings could improve the energy dissipation capacity and reduce the ultimate load-carrying capacity at the same time. Compared with the length of the openings, the width of the openings had a more significant impact on the energy dissipation capacity. (3) The peak load-carrying capacity decreased with an increase in the number of openings in the H-shaped steel.

Long -term multimodal exercise intervention for patients with frontotemporal lobar degeneration: Feasibility and preliminary outcomes

Introduction: After Alzheimer's disease, frontotemporal lobar degeneration (FTLD) is the second most common form of early-onset dementia. Despite the heavy burden of care for FTLD, pharmacological and non-pharmacological treatments with sufficient efficacy remain scarce. This study aimed to evaluate the feasibility of a multimodal exercise program for FTLD and to examine preliminary changes in the clinical outcomes of the program in FTLD. Methods: This single-arm preliminary study was conducted from July 2017 to July 2018 and recruited four male patients with FTLD aged 60–78 years. Patients exercised under the supervision of an exercise instructor once every 2 weeks for 48 weeks. The multimodal exercise program comprised cognitive training, moderate-intensity continuous training, strength training, balance training, and flexibility and relaxation training. Feasibility was measured using dropout and attendance rates. Cognitive, psychological, physical, and behavioral function tests were conducted before and after the intervention. Results: All patients completed the intervention (100%) and attended well (93.6%). Positive changes in scores in the Stroop Color Word Test (cognitive; 5 out of 6 items), Mood Check List-short form 2 (psychological), movement subscales of the Stereotypy Rating Inventory (behavioral), and timed up-and-go (TUG, physical) assessments demonstrated a medium-to-high effect size (open effect size: 0.52–0.97). While there were improvements in some domains, such as recovery self-efficacy and exercise efficacy, the MMSE-J scores showed an overall slight decline, especially in the SD case where a marked decrease was observed. Additionally, three physical function items showed no effect, except for a positive outcome in the TUG test. Functional near-infrared spectroscopy (fNIRS) revealed increased activation in the frontal lobe, indicated by elevated oxygenated hemoglobin levels before and after the exercise intervention. This pattern of activation suggests that the intervention may have stimulated neural activity in the frontal lobe, potentially enhancing cognitive and behavioral functions, including executive function and attention. Conclusion: The long-term multimodal exercise intervention may be feasible and positively change the cognitive, psychological, physical, and behavioral functions in older adults with FTLD. Although the intervention led to improvements in certain areas, there were also declines observed in various functions, which may not necessarily be due to the intervention itself but rather reflect the natural progression of the disease.

Experimental and numerical investigations on the impact of openings on the stiffness of CLT shear walls

Cross-laminated timber (CLT) exhibits high in-plane strength and stiffness, positioning it as a viable material for shear walls in seismic regions. However, the influence of openings on the in-plane stiffness of CLT shear walls remains inadequately studied. In this study, 43 CLT shear walls with different opening sizes were tested under in-plane loading. The stiffness reduction was less than 29% for openings 800×800mm (53% of panel width), but exceeded 60% for openings 1200×1200mm (80% of panel width). When assessed with identical opening sizes, 139mm and 175mm thick CLT shear walls displayed consistent stiffness reductions. Panels with an aspect ratio of 3:1 exhibited a more pronounced drop than 2:1 aspect ratio panels. A validated 3D finite element model was used to investigate the influence of panel layup and opening shape and location on the in-plane stiffness reduction. For a distance between the opening and panel edge exceeding 300mm, the shape and location of openings exerted negligible effects. Finally, the Dujič’s model was shown to be a suitable predictor to evaluate the in-plane stiffness reduction of CLT shear walls with openings.

Analysis of the Characteristics of Mesh with Complex Knitting Patterns for Spaceborne Reflector Antennas

Metallic mesh with complex woven structures is commonly used as the surface in large aperture spaceborne reflector antennas. To study the electrical properties of mesh surfaces characterized by intricate patterns, this paper presents a method for building models to analyze complex meshes. High Frequency Structure Simulator and Computer Simulation Technology (CST) simulation of the reflection coefficients, with Astrakhan’s formulation as a reference, confirm that applying the wire-grid model in CST using the tetrahedral mesh type provides sufficiently accurate results. Furthermore, the rectangular periodic wire-grid model is simulated in CST, and its results are compared with those of Astrakhan’s formulation. Correlations between reflection characteristics and influence factors, including mesh opening size, wire diameter, nature of wire contact, and wave incident angle, are investigated. To exemplify the applicability of the wire-grid model to complex mesh with irregular pattern shapes, the reflection coefficients of a warp-knitted gold-coated molybdenum mesh woven by multi-wires are measured and compared to the simulated results from the wire-grid model. The results prove that the method proposed in this paper is suitable for modeling metal mesh with complex weave patterns.

Numerical parameters study on seismic performance of short replaceable link with perforated web: Bearing capacity and overstrength

This study builds on experimental research of replaceable links with perforated web by using finite element software to develop a finite element model (FEM) of the link. The model’s reliability and accuracy were confirmed by comparing its results with experimental data. The simulation results closely match the experimental hysteresis curves, demonstrating the model's accuracy. Additionally, the simulations effectively replicated the observed failure modes, confirming the model's reliability and practical relevance. Building on this, 22 different finite element models were developed to investigate the impact of various parameters on link performance, including the shape and size of web openings, the number of openings, flange weakening depth, and link length ratio. The analysis revealed that links with circular or elliptical web openings have higher overstrength coefficients than other shapes. Additionally, as the link length ratio and flange weakening depth decrease, the overstrength coefficient tends to increase. These findings offer valuable theoretical insights and reference data for designing and optimizing replaceable link with perforated web.

Welding process stability in narrow-gap oscillating laser-MIG hybrid welding of titanium alloys with various oscillating patterns

Revealing the mechanism of laser oscillating patterns on the laser-MIG hybrid welding process stability was of great significance for improving weld formation and controlling porosity defect of titanium alloys. Convex welds were formed with poor surface formation using linear, 8-shaped and infinity oscillating laser. A circular oscillating laser with more uniform energy distribution favored the formation of concave weld. Weld porosity decreased by approximately 60 % when compared to laser with linear oscillating pattern. A keyhole with the maximum opening size was formed and fluctuated slightly. More laser-induced plasma (LIP) was ejected from the keyhole, which favored the enhancement of electric channel. Particle exchange between the arc and LIP was enhanced. Additionally, the arc burnt stably. The wire melting was accelerated to form smaller droplets, and the droplet transfer frequency increased by about 9.2 % compared with that via linear oscillating laser. Furthermore, the droplet impact force decreased by about 27.3 %. The liquid ridge (LR), formed by the droplet impact, was cushioned by the circular flow of molten metal. The droplet disturbance impact on keyhole wall was suppressed. Besides, when laser oscillated with circle pattern, the liquid metal was sufficiently diffused to rear part of molten pool, thereby suppressing convex welds.

Flexural performance of a novel bolted inter-module connection affected by corner fitting openings

Modular Steel Buildings (MSBs) are innovative structures composed of prefabricated components. The inter-module connections (IMCs) are crucial for convenient on-site assembly and overall structural integrity. Numerous IMCs exhibit openings in corner fittings to provide construction space, which reduces the strength and stiffness. The effect of these openings on flexural performance, however, remains unquantified. This study, therefore, examines the impact of opening size on the flexural performance of corner fittings, using a novel bolted IMC as an example. Flexural performance was assessed using horizontal monotonic loading tests on three specimens, with variables including box length and opening size. The failure modes, load-displacement curves, rotational stiffness, and strain responses were obtained. Subsequently, a detailed finite element (FE) model, validated against experimental data, enabled a parametric analysis on bolt sizes, end plate thickness, and opening width. Parametric analysis indicates that increasing the end plate thickness from 14 mm to 20 mm raises ultimate load-bearing capacity by 85.51 % and stiffness by 82.95 %. Theoretical formulas based on yield line theory and the component method were derived to evaluate yield load-bearing capacity and initial rotational stiffness of IMCs, considering the effect of opening size. Comparsion of these formulas with experimental and FE model resuts demonstrated good accuracy, with deviations of 9.96 % for initial rotational stiffness and 12.13 % for yield load capacity, respectively. Finally, the working mechanism by which openings influence the flexural performance of IMCs is further discussed and clarified.

Study of Behavior of EC Discharges during PMMA Machining by ECDM Process

Poly (methyl methacrylate)-PMMA material is an essential and useful material for the majority of microfluidic devices. The superior properties of PMMA, namely, optical transparency, biocompatibility and chemical inertness make the PMMA a worthy candidate for microfluidic devices. Micro-holes are one of the significant micro-features used in microfluidic devices fabricated in PMMA material. The various techniques of PMMA machining includes laser machining, hot embossing, injection molding, and mechanical cutting. Nevertheless, the usage of such processes is limited due to limitations such as higher cost, processing difficulties and machining quality. In recent times, the electrochemical discharge machining (ECDM) process has emerged as a efficient process for machining electrically non-conductive material such as glass, alumina etc. The present work is an attempt to perform micromachining in PMMA using the ECDM process. The primary mechanism of material removal in ECDM process consists of exhaustive and elevated temperature heating of the PMMA material due to the electrochemical (EC) discharges occurring at tool electrode tip in the EC region that leads to melting as well as vaporization of the material. Furthermore, the increment in the local machining region temperature enhances the rate of chemical etching which produces the smoother sidewalls of the microfeatures. The work material-PMMA, stainless steel tool electrode is kept in the close vicinity of each other in an electrochemical cell which also includes aqueous KOH electrolyte with counter ring electrode. The micro-hole quality factors such as size, depth, circularity etc. depend on the heat energy produced by EC discharges. Hence, the behavior of EC discharges greatly affects the machining process and micro-hole quality and it’s study is critical in order to achieve the micro-holes of appropriate quality for different microfluidic applications. The heat energy(q) generated, and EC discharges behavior depends majorly on the applied voltage (Va) and mean EC discharge current (Id). EC discharge behavior was evaluated by analyzing the Id values, the discharge frequency (f) with the help of current-time graphs which show the current peak stabilities and uniformities. Moreover, the stable and unstable EC discharge zones were also identified using the electrolysis current, discharge current and Va values recorded during the actual machining. The Va values up to 26 V indicated the instability region of EC discharges. The current peaks recorded for 26 V indicated the non-uniformity resulting in the micro-holes with inferior quality (higher size, lower depth, less circularity). The Va values greater than 28 V showed a higher stability as well as uniformity of EC discharges. Based on the outcome of the experimental results, superior quality micro-holes of varied sizes have been fabricated and characterized. The appropriate quality micro-holes of average opening size of ~181±5 µm with average depth of ~142± µm were achieved at the optimal range of Va i.e. 28 V to 30 V. Figure 1

Numerical simulations of the effects of KC number and entrapped water on the subsea cover hydrodynamic characteristics

ABSTRACT The entrapped water in subsea structures with openings significantly influences hydrodynamic forces and structural stability. This study utilises Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with the k − ω Shear Stress Transport (SST) turbulence model to investigate oscillatory flows around a subsea cover under varying conditions, including different levels of entrapped water (obtained by different opening dimensions) and KC numbers. Numerical simulations are validated through experimental data from oscillatory flows over a subsea cover on a plate. The study examines lift and in-line force coefficients to assess the impact of opening dimensions and KC numbers on hydrodynamic forces. Findings show that opening size primarily affects the lift coefficient due to changes in the behaviour of entrapped water. The influence of entrapped water decreases as both the KC number and opening size increase. A 30% opening yields the smallest lift-to-in-line ratio ( C Lrms / C Drms ) and reduced C Lrms and C Lstd values. Additionally, the flow fields around the cover are also discussed. Smaller openings reduce the amplitude of velocity, vorticity, and pressure inside the cover. Openings mitigate vortex formation and shedding caused by jets between the structure and the wall. The results also reveal a phase shift in lift coefficients for different opening sizes. These findings provide critical insights for the hydrodynamic behaviour and design of similar subsea structures.

Optically Transparent Complex-Amplitude Metasurface for Full-Space Manipulation of Frequency-Multiplexed Holographic Imaging.

Restricted by the physical properties of materials, most traditional metasurfaces (MSs) cannot achieve transparent stealth in the visible spectrum. Although some metasurfaces for holography have been designed, there is no standard method for evaluating the advancement of wavefront manipulation under different design algorithms. Here, a complex-amplitude metasurface with optical transparency (OT) and full-space manipulation is presented in the millimeterwave band. Through frequency multiplexing, two holographic images "HOLO" and "GRAM" with high quality are designed, achieving the signal-to-noise ratios of 14.6 and 14.4 dB, respectively. The 64 × 64 bilayered metasurface consists of glass and poly(ethylene terephthalate) (PET) substrates and three metallic mesh layers. By change of the opening size and oriented angle of split rings, phase and amplitude modulations are independently realized. Besides, a new method is provided to assess the superiority of the metasurface holography system for near-field energy regulation. The prototype was fabricated using micro-nano-technology and tested. Two holographic images were experimentally demonstrated and show good agreement with theoretical calculations and simulated results. With the advantages of OT and full-space complex-amplitude customization, the proposed metasurface holograms for frequency-multiplexed may find prospective application aspects in target perception, multichannel data storage and encryption, and many other related fields.

LATERAL STIFFNESS EVALUATION OF RESIDENTIAL ISO CONTAINER MODULE: FULL-SCALED EXPERIMENTAL AND NUMERICAL STUDIES

International Organisation for Standardisation (ISO) containers, designed to protect contents against extreme conditions, are often repurposed as temporary shelters during disasters, conflict, or urbanization. However, modifying these containers for housing greatly affects their structural integrity. Several studies have numerically and experimentally investigated the structural strength of container structures. However, there was limited information on the lateral stiffness of a residential ISO container subjected to lateral load. A piece of valuable information when the container is applied to a multi-story structure. This study proposed to conduct physical tests on two full-scaled residential ISO container structures to evaluate their lateral stiffness. Considering the actual condition of a residential container, both samples were fabricated with different sizes of openings. The finite element models of the samples were developed and analysed employing Abaqus for comparison with other studies and the experimental results. The application for lateral stiffness of ISO containers subjected to wind load was discussed based on the current design standard. The outcome of the study widened the scope of the structural behaviour of an ISO container towards the lateral stiffness of a residential container structure.

Experimental study and finite element analysis on the shear performance of steel-bamboo composite cellular beam

To study the influence of opening ratio on the shear performance of steel-bamboo composite cellular beams (SBCC), taking the opening size as the basic parameter, experimental research was carried out on five test beams. The failure modes and deformation characteristics of the specimens were observed, and the influence and law of the change of hole size on the shear performance of steel-bamboo composite cellular beams were analyzed. Through nonlinear finite element simulation calculation, multi-parameter analysis was carried out on the composite cellular beams, and the contribution of flanges to the shear performance of cellular composite beams was studied. The results show that the integrity of steel-bamboo composite cellular beams is good. The failure is mainly manifested as the fracture of bamboo web at the beam hole area, the buckling of section steel and the debonding and separation of steel-bamboo interface. The opening ratio has a great influence on the shear performance of steel-bamboo composite cellular beams. The thickness of bamboo flange cannot be ignored for the shear contribution of cellular beams. The shear capacity of cellular beams is shared by flanges and webs. The larger the opening ratio, the greater the shear contribution of flanges to composite cellular beams.

Exploring Perceptions and Preventive Practices Related to COVID-19 Among General Public: A Cross Sectional Analytical Study from Pakistan

Objective: This research was done to assess the level of public awareness, perceptions and practices using a survey questionnaire of COVID-19 in Pakistan. Study Design: Cross-sectional analytical study. Place and Duration of Study: Study was carried out from the Nov 2021 to Apr 2022 through online survey in Pakistan Methodology: The sample size calculated with open epi sample size calculator was 345. Convenient sampling technique was used. Individuals who consented and between 15 and 80 years of age were included. The questionnaire included Sociodemographic information and questions on respondents' perceptions and preventive practices regarding COVID-19,including particular inquiries about widespread misconceptions. Results: Mean age of the participants was 31±13 years. Proportions of males 159(46%) and females 186(54%) were almost equal, Majority 124(36%) were of age group 21-30 years. Half 172(50%) were graduates and 163(47%) came to knew about COVID-19 from social media Significant association between gender and source of information (p=.008) knowledge of specific cure p=0.040, maintaining social distancing p=0.002), wearing masks in public p=0.003, sanitize personal items (p=0.034)Significant association was found between age categories and source of information p<0.05 , received COVID-19 vaccine p=0.021, avoid overcrowding to prevent infection p<0.05Significant association was found between education and knowledge of specific cure p=0.001, wearing mask in public p=0.02, following government restrictions p=0.015 Conclusion: Better knowledge influences attitudes and behaviors in favor of COVID-19 prevention measures. Enhancing public knowledge, positive attitudes, appropriate behaviors, and risk perception during epidemics are necessary for disease control.

Evaluation of Pore-Former Size and Volume Fraction on Tape Cast Porous 430 Stainless Steel Substrates for Plasma Spraying.

Porous 430L stainless steel disks made by tape casting with various pore-former sizes and volume fractions were evaluated as substrates for solid oxide cell (SOC) fabrication by plasma spraying. This work reports the substrate properties relevant to the SOC operation of disks made by using extra fine metal powder with dense sintering to minimize the fine porosity between particles. In contrast, the coarse porosity is introduced by the pore former. We found that the 60 μm pore former at a 45 vol% fraction has the best application fit; it gives an adequate gas permeability of 3.11 × 10-13 m2 and an average open pore size of 45.90 μm. Compared to a commercial substrate with a similar porosity perimeter/steel area ratio, the porosity and gas permeability are 1.6 and 3 times higher, respectively. The detected maximum surface pore is 49 μm, allowing gas-tight electrolytes fabricated by plasma spray deposition.

Behavior of Concrete Beam Encasing Castellated Steel Section with Different Opening Size

This research aims to investigate the behavior of castellated steel sections with varying hole sizes enclosed in a concrete beam. Should two different opening size types (depth 140mm and depth 280mm) be used? When we use two types of shear connectors with full and partial interaction, stud connections integrate the steel and concrete parts. This research demonstrates We examined five simply-supported composite beams under two-point loading conditions. We constructed four examples using castellated steel beams and produced one specimen using standard steel beams as a control. We examine the maximum load support capacity. Examined are the specimens of composite beams' deformations. Among the many characteristics assessed are the castellated beam size of the aperture and the whole and partial composite interactions. According to test results, the sample had a 140mm hexagonal hole. The sample experienced an increase in final load percentages of approximately 11.11%. Compared to the sample featuring a 280mm hexagonal opening size, the mid-deflection and horizontal displacement showed a significant increase. The figures indicate a final load of approximately 18.82% and 16.7%, respectively. Full interaction also revealed a higher ultimate load for the sample with the same aperture. When the sample was fitted with a 140mm hexagonal hole, the percentages increased by approximately 6%. Additionally, the percentage of deflection at midspan and the percentage of horizontal displacement decreased by approximately 16.7% and 26.8%, respectively, compared to the sample with a hexagonal opening size of 280 mm.

Numerical analysis of fixed-end hollow rectangular beam under uniformly distributed load

The purpose of using opening in the reinforced concrete (RC) rectangular beam is the reduction of self-weight, cost, displacement, and strain. Therefore, this research performs linear elastic finite element analysis by using ETABS for fixed-ended RC hollow and solid rectangular beams under uniformly distributed loadings with variable beam lengths, compressive strengths, and opening sizes.The solid and hollow beams are considered to be a 2-nodded line element for the numerical analysis. The maximum range of validation result in case of hollow beam is found to be (3.9 to 7.9) %, which may indicate good accuracy of numerical analysis. The 50 × 50 mm opening size is suitable for 300 × 300 mm RC rectangular beam because of showing the positive normalized deflection of (0–1.45) % and lower strain rates (i.e. 0.13 % and 0.17 %) to compare the solid beam. This research may help professional engineers to use suitable opening size for design and construction works. Although, there is a scope to enhance this research in future by performing nonlinear analysis.

Effect of natural ventilation on aerosol transmission and infection risk in a minibus

High passenger density, prolonged exposure, and close interpersonal distance create a high infection risk (IR) in minibuses. While improving natural ventilation induced by turbulent airflows is essential for controlling IR in minibuses, comprehensive studies on its effectiveness are lacking. To address this, we conducted computational fluid dynamics simulations studies coupling indoor–outdoor turbulent airflows to examine the impact of window opening locations, window opening sizes, and initial droplet diameters (dp) on the ventilation airflow and dispersion of pathogen-laden droplets. Results show that the surrounding turbulent flow patterns create higher surface pressure at bus rear than bus front, which is a key factor influencing bus ventilation. When all windows are closed, ventilation is primarily provided by skylights at bus rooftops. Ventilation through only two skylights resulted in an air change rate per hour (ACH) of 17.55 h−1, leading to high IR of passengers. In contrast, fully opening front and rear windows increases ACH by 27.28-fold to 478.79 h−1, significantly reducing IR by 1–2 orders of magnitude compared to skylight ventilation. Expanding window opening sizes can effectively enhance ventilation when both front and rear windows open (attributed to the pumping effect), while is ineffective when only front windows open. To reduce IR in minibuses, we recommend opening multiple windows at the bus front and rear. Even if the total opening area of the front and rear windows is only two-thirds of that of the front window, its ACH is 2.8 times more than only opening front windows.

A Influência da Abertura de Janelas na Eficiência Energética de Edifícios de Escritórios

The construction sector is responsible for a significant portion of energy consumption and greenhouse gas emissions. Therefore, it is crucial to develop initiatives that identify and reduce energy consumption in buildings from the planning stage, contributing to the sustainability of these constructions. In this context, this study aims to examine the influence of window opening size in a model of an office building located in Passo Fundo, RS, in Bioclimatic Zone 2 (ZB2). To this end, six computer simulations were performed using Energy Plus software in a model of an office building, considering windows occupying 25%, 50% and 100% of the building's façade size. Tests were also performed using single and double glazing. The results revealed that the larger the window opening, the greater the energy consumption to maintain thermal comfort in the environment, representing an increase of 11.36% in consumption for the case with 100% window opening compared to the case with 25% opening. Thus, the size of the window opening has a significant impact on the energy consumption of the office building model analyzed.

Measuring pore sizes of nonwoven geotextiles by X-ray CT images: a comparative evaluation

This paper focuses on evaluating the pore sizes of four nonwoven geotextile specimens with different pore size distribution techniques. The paper introduces a bubble analysis technique to find the two-dimensional (2D) pore size distribution of geotextile specimens. A new method is also introduced to determine the three-dimensional (3D) constriction sizes of nonwoven geotextiles from X-ray CT images. The digital image concept and image processing methods for the 2D image analysis and 3D constriction size measurement of geotextile specimens are explained. Finally, the paper compares the 3D constriction sizes with those measured from 2D image analysis, mercury intrusion porosimetry, manufacturer-reported opening size values based on the wet sieving method, and pore sizes calculated from theoretical equations. The results show that the largest pore opening sizes measured from the 3D constriction size method are in good agreement with the theoretical equations. The values measured from the wet sieving method were found to be the smallest, indicating the limitations of the wet sieving method to determine the largest pore opening size of nonwoven geotextiles. As it is the constriction size which must control filtration behaviour, the 3D constriction size method is recommended for assessing the reference porometry.