Shape Of Opening Research Articles

Energy dissipation in hydraulic jumps using triple screen layers

In the present study, series of laboratory experiments were conducted to investigate the effectiveness of perforated screens as energy dissipators in mixed triple wall mode in the case of small hydraulic structures. The shapes of openings for each layer of screens were either circular, square or triangular. Every layer of the screen had a porosity of 45% per unit depth of the screen. The experiments were conducted to dissipate the energy for supercritical flows of Froude number F1 ranging from 3.2 to 19.3. The screens were placed vertically with the first screen 1.5 m from the sluice gate and consecutive screen at a gap of 25 mm. The experiments showed that the energy of the supercritical flows can be dissipated effectively by using perforated screens. The difference in energy dissipation between the upstream and downstream of the screen was more significant than the energy dissipation caused by classical hydraulic jumps. Comparing the results of the present study with the previous researchers it is found that the energy loss in case of present study more than the previous researchers. The relative energy loss in the present study was found to be varying from 74 to 94%. The value of the Froude number downstream of the screen, F2, was varying from 1.1 to 1.81, with an average value of 1.35. Tailwater deficit parameter, D, if found to be varying from 0.66 to 0.90.

Study on anti-progressive collapse performance of cellular steel frames with different web opening shapes

In this paper, cellular beam-column joints with different opening shapes were taken as the object of study to investigate the resistance to progressive collapse of weakened beam-column joints through a combination of experiments and numerical simulations. Opening shapes include circular, rectangular and hexagonal. The development laws of failure mode, vertical force–deformation response, internal force development and resistance mechanism of the specimens were analyzed, and based on the validated finite element model, the effects of weakening parameters of openings with different opening shapes on the performance of the beam-column joints against progressive collapse were studied. The results demonstrate that the load carrying capacity and deformation capacity of cellular joints with different opening shapes have different degrees of improvement compared with the foundation joints, and exhibit the largest deformation in the first opening area near the column flange, where the ductile failure at the weakened section occurs in the hexagonal cellular opening, and the catenary effect can be fully developed, showing the best performance under the designed opening size, rectangular is the second and circular the worst. In addition, the failure mode and load carrying capacity of the specimens can be effectively improved by changing the opening weakening parameters. Increasing the opening diameter (parameter a) and opening edge distance (parameter c) within a reasonable range can effectively improve the vertical resistance and deformability of the specimens, and the effect of opening spacing (parameter b) on the structural load response is negligible. In the design of collapse resistance of cellular beam-column joints, it is recommended to increase the values of parameters a and c appropriately and to reduce the value of parameter b appropriately under the premise of ensuring the structural load carrying capacity, which is more conducive to the catenary action.

PEMBAYANGAN MATAHARI DAN PERHITUNGAN PEMBUKAAN DINDING DENGAN SOFTWARE AMETHYST SHADOW-FX

The buildings design in the tropics climate, shading on the walls is needed to prevent the entry of sunlight into the building. Shading is needed by determining the length of the sun shading and the placement of the height of the window, according to the orientation of the designed building. The purpose of this research is to determine the design of the building against the effort to block the entry of sunlight into the building with the simulation of Amethyst Shadow-FX software. The research method used is Ex Post Facto, where the independent variables are given treatment, namely variations in the shape and size of the wall opening and the orientation of the building. The results of this study are guidelines for designing building facades in the tropics and orientations that can produce thermal comfort in buildings because temperature increases can be avoided.

Genetic Analysis of Mutagenesis That Induces the Photoperiod Insensitivity of Wild Cotton Gossypium hirsutum Subsp. purpurascens.

Cotton genus Gossypium L., especially its wild species, is rich in genetic diversity. However, this valuable genetic resource is barely used in cotton breeding programs. In part, due to photoperiod sensitivities, the genetic diversity of Gossypium remains largely untapped. Herein, we present a genetic analysis of morphological, cytological, and genomic changes from radiation-mediated mutagenesis that induced plant photoperiod insensitivity in the wild cotton of Gossypium hirsutum. Several morphological and agronomical traits were found to be highly inheritable using the progeny between the wild-type G. hirsutum subsp. purpurascens (El-Salvador) and its mutant line (Kupaysin). An analysis of pollen mother cells (PMCs) revealed quadrivalents that had an open ring shape and an adjoining type of divergence of chromosomes from translocation complexes. Using 336 SSR markers and 157 F2 progenies that were grown with parental genotypes and F1 hybrids in long day and short night conditions, five quantitative trait loci (QTLs) associated with cotton flowering were located on chromosomes At-05, At-11, and Dt-07. Nineteen candidate genes related to the flowering traits were suggested through molecular and in silico analysis. The DNA markers associated with the candidate genes, upon future functional analysis, would provide useful tools in marker-assisted selection (MAS) in cotton breeding programs for early flowering and maturity.

Analytical Study of the Behavior of Steel Beam-Columns with Different Shapes of Web Opening at Different Location

Analytical Study of the Behavior of Steel Beam-Columns with Different Shapes of Web Opening at Different Location

Comparative Analysis of Curved Beam with different Types of Holes in Middle Section by use of Ansys Software

Reinforced concrete beam with transverse web opening is a facility that allows the services such as telephone lines air conditioning and ventilating ducts, to pass through the structure. Because of the change in the beam section the corners of the opening are subjected to large concentration of stress, possibly producing oblique cracks in the beam. The region nearby the openings are measured as the weaker part of the beam. Therefore, a decline in bearing capability and also a change in the load transport mechanism is experienced. This thesis investigates the analytical study on the influence of various opening shapes with constant area on shear behavior of RC beams without extra shear reinforcement around the opening. In this thesis nonlinear analysis using ANSYS 18.1 is used to analyze the beam. The RC beam with opening is a method that permits the services to move towards the construction. Due to rapid changes in the beams crosssection, the edges of the opening stimulate crosswise cracks and can be subjected to high stress concentrations. The reliability and constancy of the beam will then be considered compromised, and the regions nearby the opening is the weakest element of the beam. Therefore, a decline in the bearing capability and also a change in the load transport mechanism is experienced. If safety actions are not in use, preventable accidents are likely to ensue.

Voice rehabilitation after laryngectomy: problems, complications and ways of their elimination

Voice rehabilitation after laryngectomy: problems, complications and ways of their elimination

Dimension Analysis of Bending Perforated Beams with the Evolutionary Topological Optimization Method

The aim of this study is to determine the optimal shape and clearance of the web openings in order to both increase the carrying capacity and decrease the weight of classic perforated beams by using evolutionary topological optimization technique. The effects of the optimal shape and web openings has been obtained by the application of the evolutionary topological optimization through finite elements method, and then the obtained optimal beam has been compared with widely used perforated beams in the market by using stress and displacement analysis. The designed beam was seemed to have more advantages then the widely used ones in industry with a less weight and higher carrying capacity. With the topology optimization, the usual classic perforated beams’ geometry has been changed and stiffness was improved.

Intermediate-severity disturbance impacts in a mixedwood forest: A multi-scale analysis

Mixed Quercus-Pinus stands are increasingly desired by forest managers to achieve a range of objectives, including biodiversity enhancement and resilience to global change. To create and perpetuate desired mixed Quercus-Pinus stand composition and structure, quantitative information on natural disturbance impacts on stand development and succession is necessary. Wind is the most common natural canopy disturbance in eastern North America, and impacts vary in severity and spatiotemporal scales. Intermediate-severity disturbance (ISD; events that occur along a classification gradient between frequent gap-scale and infrequent, stand-replacing events) is hypothesized to be an important driver of mixed Quercus-Pinus creation and maintenance. Our overarching goal was to quantify patterns of intermediate-severity wind disturbance in a mixed Quercus-Pinus echinata Mill. forest on the Cumberland Plateau in Tennessee, USA. Specifically, our objectives were to: 1) quantify post-disturbance species composition, stand structure, and residual tree spatial patterns, 2) infer individual-tree, neighborhood, and site-specific impacts on tree mortality, and 3) describe frequency, size, shape, and spatial distribution of ISD-created canopy openings. We inventoried plots in Pinus echinata-dominated, disturbance-impacted portions of the forest. To infer individual-tree and spatially-explicit neighborhood characteristics that influenced survival probability, we applied a random forest classification algorithm. To document changes in tree spatial distribution before and after disturbance, we used spatial point pattern analysis. To characterize forest-scale disturbance patterns, we classified canopy gaps from high-resolution orthoimagery. The most important predictors of survival were basal area, taxonomic group, and distance to nearest neighbor. Pre-disturbance trees and residuals were spatially randomly distributed. Most detected openings were 50–150 m2, and the opening size-frequency distribution exhibited a reverse J-shape. Openings were spatially clustered within the forest at distances < 200 m and complex in shape. We provide quantitative recommendations on the frequency, size, shape, and spatial distribution of silvicultural entries patterned after natural disturbance. To emulate natural disturbance patterns, we recommend patch seedtree harvests with reserves or patch clearcuts with reserves, and these harvest-created openings should be concentrated (i.e., clustered) in portions of the stand in which P. echinata is most dominant and/or most competitive. Site preparation with prescribed fire, herbicide, and/or mechanical thinning may also be necessary to prepare the seedbed and reduce hardwood competition to favor Pinus establishment in openings.

RANS CFD modeling of the flow around a thin windbreak fence with various porosities: Validation using wind tunnel measurements

In computational fluid dynamics (CFD) simulations of airflow in built environments, the porous-jump model is commonly used to represent extremely thin porous windbreak fences, which have much smaller sizes than the neighborhood computational cells. However, owing to the limited quantitative validation studies that include turbulence characteristics, no clear guidelines exist on modeling such thin porous fences in CFD simulations. In this study, pressure loss coefficients of porous materials with various porosity values and opening shapes were determined using a small wind tunnel while the velocity and turbulence statistics behind the fences were measured in an atmospheric boundary layer wind tunnel. Two separate CFD models based on the Reynolds-averaged Navier–Stokes equation and porous-jump models were used to mimic the airflow in each wind tunnel and then they were validated using the experimental results. The results showed that the pressure loss was accurately predicted by CFD simulations. For wire-mesh fences, a good agreement was obtained between experimental and numerical results for the mean streamwise velocity and turbulent kinetic energy (TKE), whereas the velocity deficit and TKE were overestimated and underestimated, respectively, for the non-wire-mesh fences. This study can be used to improve the performance of thin porous windbreak fences.

Buckling Analysis of a Thin-Walled Structure Using Finite Element Method and Design of Experiments

In structural engineering, thin-walled structures play an important role in the design of the lightweight structural model. It carries different loading conditions when it exists in any model, and it is designed with thin plates or thin shells. Penetrating thin-walled structures with different kinds of holes can decrease their weight and facilitate repair and maintenance operations, such as those carried out for the wing of an airplane. In such applications, cutouts are often employed as part of the design of composite plates. Therefore, this paper attempted to design and analyse the thin-walled composite structure with a C-cross-section shape. To model and analyse the structures, a finite element method was utilized using the ABAQUS commercial tool, and the results of critical buckling load for different laminate types were obtained. Composite materials and structures have different parameters that can vary the results of analysis; therefore, to optimize the current mode a design of experiments method is used via MINITAB 20 and Design-Expert 13 tools. The selected parameters for this work were the opening ratio, spacing ratio, and shape of the hole for the output response as a critical buckling load was carried out. Based on the current results of simulation and optimization, it was found that the parameters of composite materials and structures will impact the output response, and the current study investigated the optimum parameters for the best possible outcome of the structural analysis.

Numerical investigation on strengthening steel beams with web openings using GFRP

This study presents the first investigation into the use of glass fiber reinforced polymer GFRP to strengthen steel beams with web openings. Based on previous research about the strengthening of steel beams with web perforation using carbon fiber reinforced polymer (CFRP) conducted by one of the contributing authors of this paper, it was decided to investigate the ability of pultruded glass fiber reinforced polymer, which is less expensive than CFRP materials, to strengthen single rectangular web openings of steel beams. The previous published experimental test was used to validate the proposed numerical model developed with the finite element software ABAQUS, capable of acquiring important phenomena such as debonding between FRP and steel material. The validated simulation was then used to operate a parametric study involving four proposed GFRP strengthening techniques and three distinct pultruded GFRP product thicknesses to reinforce the same steel beam used in the earlier experimental test, having a single rectangular opening shape in two separate positions along the span. From these numerical models, an adequate GFRP strengthening arrangement was found and the possibility of using low-modulus FRP materials rather than the more expensive high-modulus FRP materials for strengthening steel beams with web penetration was confirmed.

Prediction of the castellated beams deflections

Introduction. Existence of openings in webs of beams reduce their shear rigidity and increase deflections compare with beams of the same dimensions with solid web. Investigation of the castellated beam’s deflections is important, because one of main demands to beams of engineering structures is guarantee of necessary rigidity, i.е. restriction of ratio deflection to length. In the work it was studied deflections of castellated beams with diamond shape, hexagonal, sinusoidal and circular openings, widely used in structural industry.&#x0D; &#x0D; Materials and methods. Effect of openings on transverse deflections of the castellated steel beams was studied analytically with theory of composite bars, with the finite element method and experimentally on four meters’ double consoled beams under loading with concentrated forces applied at consoles.&#x0D; &#x0D; Results. Universal analytical relation was obtained which allow reliably evaluate deflections of simply supported beams with various shape of openings under different kind of loading. Analysis of results of calculation of beams by FEM using program complex ANSYS demonstrates satisfactory correspondence to experimental data and to analytical relations.&#x0D; &#x0D; Conclusions. Obtained with the theory of composite bars analytical dependences for deflections of simply supported beams are applicable for beams with various type of perforation and different kind of loading.

Effect of opening shape, size and location on the punching shear behaviour of RC flat slabs

The current study aims to investigate the effect of opening size, location and shape on the punching shear behaviour of Reinforced Concrete (RC) flat slabs. Ten two-way slabs with a span of 1600 mm and a thickness of 120 mm were tested under a static load applied on a central stub column. The test program was divided into three groups with openings and a control slab without opening. Group I was designed to study the effect of opening size, thus, three slabs with three different opening sizes were tested. The openings dimensions were 200 × 200, 300 × 300 and 400 × 400 mm2. These openings were created beside the column. On the other hand, in group II, three slabs with the same opening size of 300 × 300 mm2 were tested, when the openings were at different locations. The distances between the opening edge and the column face were 100, 200 and 300 mm. To study the effect of opening shape, the slabs of group III having circular openings were tested. The openings’ diameters were 250, 350 and 450 mm, these values were configured to equalize the areas of the square openings of group I. The test results indicated that the slabs’ capacities and stiffness notably decreased with increasing the opening size. However, the percentage of the decrease could be reduced by increasing the distance between the column and the opening and/or using a circular opening. The ultimate experimental punching shear capacities of slabs with openings were compared with those obtained by the equations of ECP-203, ACI-318 and EC2 codes. Based on this comparison, ECP-203 and ACI-318 showed higher factors of safety than EC2.

Study on the output performance of the proton exchange membrane fuel cells using print circuit board

This paper presents a proton exchange membrane fuel cell (PEMFC) using anode and cathode printed circuit boards (PCBs) to load the membrane electrode assembly (MEA). A three-dimensional CFD-electrochemical model of the PCB-based PEMFC is developed and used to calculate the internal species, charge, and water distribution. The effects of the shape of the inlet opening, the opening ratio and the relative humidity of the air on the output performance of the PEMFC are investigated. To validate the simulation model, the output performance of the PEMFC is tested under the same operating conditions. The results show that circular and rounded rectangular openings show better PEMFC output performance than U-shaped openings, and the output performance of PEMFC is improved as the opening ratio of the inlet openings and the relative humidity of air increase. The results will provide specific reference values for the design of PCB-based planar PEMFC stacks.

Hydrogen detonation onset behind two obstructions with unequal blockage ratio and opening geometry

Experiments on detonation onset behind two solid obstructions with uneven blockage ratio (BR) and opening shape were carried out in premixed, stoichiometric, hydrogen-oxygen mixtures at 20 kPa. Three geometric features of the second obstruction (OB2) were investigated: the opening shape, BR, and minimum opening vertical dimension (d/λ). Obstructions with blockage ratio increase across the obstacle pair (40%–80% and 40%–60%) presented shorter detonation onset time than obstacle pairs with unvaried BR (40%–40%). Modifications in the second obstacle geometry for pairs with 40%–40% and 40%–80% blockage had minimal effect on DDT time and obstacle-induced shock strength. Conversely, obstacle pairs with 40%–60% blockage experienced significant variation depending on the geometry employed. Critical conditions of detonation initiation immediately behind the second obstacle were found to correlate with BR and effective opening dimension (deff/λ); For OB2 with 60% and 80% BR, DDT limits correlate well with the upper and lower limits constrained by D−deff2λ≥1 and deffλ≥1, respectively. The Taguchi analysis showed that the second obstacle blockage is the factor that most influenced early detonation onset, both the shape and opening dimension had minor effects. This finding confirms the importance of BR pattern for overpressure estimation during gaseous explosions.

Shear behaviour of ultra-high performance concrete beams with openings

An experimental investigation of the shear behaviour of Ultra-high performance concrete (UHPC) beams with web openings was conducted. Eight UHPC beams were experimentally cast and subjected to a four-point bending test. One beam, which was considered the control specimen, had no web openings, whereas the seven other beams contained openings. The studied parameters were steel fibre content, opening position, opening shape and reinforcement schemes around the web openings. Shear behaviour was evaluated on the basis of cracking patterns, load-deflection behaviour, ductility, initial stiffness, toughness and strain. Experimental results showed that increasing the volume fraction of steel fibres enhanced the shear strength, stiffness, toughness, ductility and strain in steel reinforcements. The presence of web openings in the shear region led to a decrease in the shear strength by 33.7%. The ultimate load of UHPC beams with openings has been evidently improved using reinforcement around the openings. An analytical verification was proposed to evaluate the experimental test results of UHPC beam by using design codes, different prediction equations and the empirical equation proposed herein. The proposed empirical equation showed an excellent agreement with available experimental data.

Clinical effect and analysis of exercise treatment for temporomandibular joint osteoarthritis

Objective: To explore the clinical efficacy of (stomatognathic system functional exercise(SSFE) in the treatment of temporomandibular joint osteoarthritis (TMJOA), and to provide reference for the clinical treatment of TMJOA. Methods: Choose between January 2020 and June 2020 in the Affiliated Hospital of Qingdao University of Temporomandibular Disorder (TMD) Clinics, pain in the temporomandibular joint (TMJ), limited openings for complained of symptoms of TMD patients, diagnosed by clinical examination and cone beam CT (CBCT) examination of TMJOA patients 60 patients (64 joints), including 20 males and 45 females, the age was (42.6±2.5) years (33-47 years old). The patients were randomly divided into the experimental group (30 cases, 34 joints) and the control group (30 cases, 30 joints) according to the odd and even numbers of their treatment numbers. The experimental group was treated with SSFE method. The control group was treated with maxillary full dentition occlusal splint. Visual analogue score (VAS), natural mouth opening and maximal mouth opening (MMO) of each patient in each group were recorded at initial diagnosis, 2 weeks, 3 and 6 months after treatment, and CBCT imaging was compared for the changes of condylar bone at initial diagnosis, 3 and 6 months after treatment. Results: VAS values of the experimental groups were (2.90±1.42), (0.90±0.37), (0.87±0.23) at 2 weeks, 3 and 6 months after treatment, respectively. The VAS values of the control group were (4.57±1.94), (4.17±2.09), (3.73±2.21), respectively. The VAS score of the experimental group was significantly lower than that of the control group (F=42.93, P<0.001). Before SSFE treatment, all the patients in the experimental group had different degrees of restricted opening and characteristic abnormal opening and closing pattern. Two weeks after SSFE treatment, the opening degree of the patients was (37.69±2.4)mm, the opening shape "↓" and the closing shape "↑" were normal. At 3 and 6 months after treatment, the oral opening was (38.98±1.08) mm and (39.73±1.76) mm, respectively. The opening degree of control group was (36.85±2.33) mm 2 weeks after treatment, and the characteristic abnormal opening and closing pattern still existed. The opening degree of control group was (37.82±1.85) mm and (37.40±1.75) mm 3 and 6 months after treatment, respectively. The characteristic abnormal opening and closing pattern (stuffy, awkward, deliberate, unnatural) did not improve significantly. The openness of the experimental group was significantly higher than that of the control group (F=25.20, P<0.001). In the experimental group, 82.4% (28/34) had benign remodeling of condylar bone 6 months after treatment, and 17.6% (6/34) had no change of condylar bone. There was no significant change in condylar bone in control group. CBCT scores of the experimental group were (2.43±1.74) and (1.70±1.26) at 3 and 6 months after treatment, respectively. CBCT scores of the control group at 3 and 6 months after treatment were (4.23±1.50) and (4.10±1.37), they were significantly lower in the experimental group than in the control group (F=27.20, P<0.001). Conclusions: Full dentition occlusal splint can alleviate the pain in the joint area of TMJOA patients, but can not improve the characteristic abnormal mandibular movement, and the condyle bone repair is not obvious. SSFE can effectively relieve the symptoms and signs of TMJOA patients, especially improve the abnormal characteristic mandibular movement, and promote the normal reconstruction and repair of condylar bone.

КОНЕЧНОЭЛЕМЕНТНЫЙ АНАЛИЗ ОБЩЕЙ УСТО ЙЧИВОСТИ БАЛОК СО СПЛОШНОЙ И ПЕРФОРИРОВАННОЙ СТЕНКОЙ

Influence of perforation on the lateral-torsional buckling of I-beams with plane and castellated web in elastic stage of loading was considered with help of the finite element method, which allow to analyze critical loads of castellated beams and beams with plane web. Calculations were performed for simply supported beams under uniformly distributed load and concentrated forces, applied symmetrically at different distances from supports. Numerical calculations were carried out with help of program complex ANSYS on specially elaborated program. For castellated beams under constant relative depth of openings there were varied such parameters as shape and step of openings. Performed comparison of results with existing in literature analytical calculations of beams with plane web allow to confirm accuracy of existing formulas.

Mechanism of stress distribution and failure around two different shapes of openings within fractured rock-like materials

Mechanism of stress distribution and failure around two different shapes of openings within fractured rock-like materials