Shape Of Opening Research Articles

A comparative study on water entry and water walking events of elastic spheres

This paper presents a comparative study on water entry and water walking events of elastic spheres using a fluid–structure interaction method. The sphere displacements, cavity formations, and hydrodynamic characteristics during the water entry and water walking events are investigated. When the impact angle decreases, an obliquely impacting elastic sphere on the water surface can undergo a transition from water entry events to water walking events. Based on the morphological classification of the cavity opening, the shapes of cavity openings formed by elastic spheres can be roughly predicted from material properties and impact conditions. Furthermore, the water walking event is characterized by three typical stages: impact below the surface, walking across the surface, and skipping from the surface. Each stage is analyzed in terms of sphere displacements and hydrodynamic characteristics. The results also show that the vertical hydrodynamic forces acting on elastic spheres are not always smaller than those acting on rigid spheres at all impact angles. The critical impact angle that results in an equivalent vertical hydrodynamic force acting on both elastic and rigid spheres can be predicted from the material properties and impact conditions of the elastic sphere.

Karakter pintu masuk sarang kelulut (Apidae: Meliponinae) di Kawasan Konservasi Resort Belaban Taman Nasional Bukit Baka Bukit Raya Kalimantan Barat

Informasi karakter pintu masuk sarang kelulut (Hymenoptera: Apidae: Meliponinae) sebagai penciri identifikasi spesies kelulut belum pernah dilakukan lebih mendalam. Tujuan penelitian ini adalah untuk mengetahui karakter penciri morfologi pintu masuk sarang yang membedakan antar spesies kelulut yang ditemukan di kawasan konservasi Resort Belaban, Taman Nasional Bukit Baka Bukit Raya. Penelitian dilakukan pada tanggal 16–26 Maret 2022. Metode yang digunakan dalam penelitian ini adalah metode jelajah dengan mengikuti arah jalur interpretasi Resort Belaban. Analisis data dilakukan dengan software PAST 4.03. Berdasarkan sampling dan identifikasi spesies, ditemukan 32 pintu masuk sarang dari 7 spesies kelulut, yaitu Homotrigona fimbriata (Smith), Pariotrigona pendleburyi (Schwarz), Tetragonilla collina (Smith), Tetragonula iridipennis Smith, T. melanocephala (Gribodo), T. melina (Gribodo), dan Tetrigona apicalis (Smith). Hasil PCA menunjukkan bahwa karakter morfometrik dan meristik paling menonjol dalam PC 1 (eigenvalue = 4,89; % variance = 44,51%) yang dapat digunakan sebagai penciri masing-masing pintu masuk sarang kelulut adalah luas bukaan rongga pintu masuk (0,66), variasi warna (0,78), paparan sinar matahari (0,85), dan variasi bentuk corong pintu masuk (0,57). Penelitian ini menunjukkan terdapat variasi karakter meristik dan morfometrik dari pintu masuk sarang kelulut. Meski demikian, identifikasi suatu spesies kelulut berdasarkan karakter pintu masuk sarang belum dapat digunakan secara valid sehingga hanya sebagai perkiraan sementara.

Natural frequencies of RC concrete slab with opening

Vibration analysis of plates with openings represents an important issue in civil, aerospace, and mechanical engineering applications. It has been familiar that the opening or cut-out may be considered as a defect in most cases, which generally leads to a decrease in the stiffness of the member, according to the opening’s size, shape as well as location. Hence, it affects the dynamic properties, for instance, the natural frequencies and the mode shapes. In this work, numerical modal analysis of fixed ends supported RC concrete slabs with three different aspect ratios as well as two different central square and circular openings has been investigated. The study is based on evaluating the natural frequency of these cases, as a global parameter. A simulation process for the modal analysis using ANSYS software is done to compare the results. The natural frequencies of RC concrete slab with openings have been evaluated and compared with each other as well as with the intact slab, as control ones. The results showed that both two shapes of central openings have an impact on the natural frequencies of the slab depending on sizes and aspect ratios.

Experimental and Numerical Investigation of the Buckling Behavior and Strength of Combined Opening Plate Girders in Passenger Ships

High-stiffener-web combined opening girders used on passenger ships are prone to plastic hinge failures around the opening area and overall instability under combined and vertical loads, exhibiting complex buckling behaviors. In response to such situations, a series of numerical simulations and experiments on combined opening girders were conducted, considering several affecting factors such as opening shapes, initial crack defects, strengthening measures and stiffener web dimensions. On the basis of the verification of the reliability of the numerical method, the load-bearing characteristics of the combined open plate girders were investigated. It is concluded that the lumbar round opening can lead to localized plastic hinge failure phenomena, complicating the buckling behavior. In contrast, the inclusion of stiffeners can significantly improve the load-bearing capacity after the point at which instability occurs in the original specimen. In addition, detailed relationships between deformation trends and external loads are illustrated, which can be used as a reference for the optimal design of combined opening plate girders in actual ship structures.

Experimental Study of Pre-Cast Reinforced Concrete Deep Beams (Hallow Core section) Retrofitting with Carbon Fiber Reinforced Polymer (CFRP)

Experimental programs based test results has been used as a means to find out the response of individual elements of structure. In the present study involves investigated behavior of five reinforced concrete deep beams of dimension (length 1200 x height 300 x width150mm) under two points concentrated load with shear span to depth ratio of (1.52), four of these beams with hallow core andretrofit with carbon fiber reinforced polymer CFRP (with single or double or sides Strips). Two shapes of hallow are investigated (circle and square section) to evaluated the response of beams in case experimental behavior. Test on simply supported beam was performed in the laboratory & loaddeflection, strain of concrete data and crack pattern of those five reinforced concrete beams was recorded. Parametric studies are also conducted in this study includes the effect of hallow opening (shapes and materials), and CFRP ratio (single, double strips and side horizontal stirrups). Comparisons of test results from experimental data are based on load capacity, deflection, crack pattern and strain of concrete for all beams. From this comparison it was found that hallow effect on strength capacity i.e. decrease by about (13%) and increased in deflection and strain by about (18%, 24%) respectively compared with solid section. Also find that CFRP give more enhancements in loading capacity by about(33 to 66%) and decreased deflection for same applied load by about (26%). Test results that show when sides of beams retrofit with CFRP strip against horizontal shear increased strength by about by (20%). Finally the using double CFRP strips for hallow section gives equivalent or more than strength capacity of solid section.

The structure of thin boron nanowires predicted using evolutionary computations

This work describes the implementation of a genetic algorithm-based strategy combined with first-principles computations for identifying the structure of the most stable boron 1D crystals. We focus our attention on the structure of ultrathin 1D boron crystals given the lack of previous experimental and theoretical work on this topic. Our methodology yields low-energy structures for further optimizations at the DFT level with tighter convergence criteria. The simulations involved 1D crystals with up to 8 atoms per unit cell. We have identified four main groups of structures: flat nanowires (monatomic-height stripes) with triangular or triangular and “square” motifs, stripes with larger holes, nanowires with an open tubular shape, and regular nanowires. The diameter-dependent structural changes are discussed.

DYNAMICS OF VIBRATION GRINDING WITH REGARD TO THE INFLUENCE OF SORTING MATERIAL ON ITS WORKING PARAMETERS

The general calculation model of the screen system was determined - the material is based on the study of the interaction processes between the sieve and the crushed stone that was on the screen. The selected model of vibration movement of loose material made it possible to determine the qual-itative and quantitative characteristics of the dynamic impact on the working body. The sorting process is presented as some orderly process of movement of a large number of different particles in a layer on a sieve. The main provisions for the calculation of the main parameters of the screen are formulated, which ensure the specified modes of the process of sorting the material and obtaining the appropriate fractional composi-tion of crushed stone. The prerequisite for choosing the calculation scheme "screen-sieving material" is the determination of the vibrational movement of a material particle along a vibrating hard surface inclined to the horizon at an angle that carries out rectilinear oscillations at an angle to the plane of the screen. At the same time, weight, friction force and normal reaction act on the particle. The proposed model made it possible to determine the speed of transportation in the case when the screening screen performs a circular motion, which is the addition of two independent oscillations with different amplitudes and frequencies. The sorting process is significantly affected by the probability of grains passing through the holes of the sieve. This prob-ability depends on the size of passing particles, the dynamic parameters of screen vibrations, the design of the sieve, the shape of the sieve openings, the coefficient of the live section (the ratio of the area of the openings in the light to the total area of the sieve. The average speed of passage of particles through the sieve is determined by the frequency of contact of particles with the surface and the ratio of particle sizes and the hole. The frequency of particle contact with the sieve is affected by the amplitude and frequency of vibrations of the sieve surface. The probability of a particle passing through the sieve hole during one collision can be estimated based on the calculation charts.

Dynamic mechanical properties and failure behaviors of brittle rock materials with a tunnel-shaped opening subjected to impact loads

Since the surrounding rocks of underground tunnels are frequently suffered from the dynamic disturbance of mechanical percussion drilling and explosive blasting, it is significantly meaningful to investigate the mechanical properties and failure behaviors of rock material with a tunnel-shaped opening under dynamic loads. In this work, seven groups of prismatic samples, including the intact samples and the samples with a circular opening of three kinds of diameters, a square opening, a horseshoe-shaped opening and a D-shaped opening, were prepared for dynamic compressive loading. The results show that the prismatic specimens satisfy the stress uniformity condition in impact tests using SHPB testing system with a bar diameter of 50 mm. The weakening effects of the existed openings on the dynamic compressive strength, elastic modulus and peak strain of rocks are closely associated with the size and shape of opening and the loading direction. Based on the energy parameters of the samples, the dissipated energy density of each group of samples can be solved. The failure degree of the samples characterized by dissipated energy density and fractal dimension are in good agreement. Besides, the failure mode of the intact specimen belongs to splitting tensile failure, while that of the pre-holed specimens can be classified as shear-dominated failure due to the coalescence of the openings and the shear cracks occurring along the diagonals of the specimens. The test results provide some insights into the mechanical behavior of rock materials under dynamic loads and lay an important theoretical foundation for support design and rock disaster prevention of underground tunnel.

Effect of openings on simply supported reinforced concrete skew slabs using finite element method

Abstract Reinforced concrete skew slabs are commonly used in bridges due to space constraints in motorways and in congested urban areas. Such slabs also often need to contain openings for architectural requirements or services, and this study seeks to determine the effect of these openings on the strength of the skew slabs. The finite element method was used to analyze 13 cases of slabs with skew angles of 45°. The first and second cases were used to validate the results with experimental work. Other cases studied the effect of the position and shape of openings on the strength of the skew slabs under both one-point and four-point loading conditions. The study also showed that the worst location for the opening was near the obtuse corners since this is where most of the load is transferred. With respect to the shape of openings, three different shapes with the same area were used: skew, circle, and square shapes. It was found that the effect of the opening shape depends on how many steel reinforcements are removed, as well as the appearance of negative cracking brought on as a result of the opening. Overall, the square shape introduces the smallest reduction in the skew slab strength compared with a slab with no opening. Accordingly, the study recommends that the strength of skew slabs can best be maintained if square openings are employed near the acute corners, alongside negative steel reinforcement to avoid cracking.

Shear strength design of cold-formed steel channel sections with web openings

Cold-formed steel (CFS) members are increasingly used as the main loading-bearing elements in modern construction practice, due to the advantages such as high strength-to-weight ratio, and ease of transportation and assembly. Often, web openings are cut out of CFS elements to allow for services, plumbing, heating and electrical systems, which may result in considerable reductions in their shear strength. This study aims to investigate the behaviour and design of CFS channel members with web openings under shear loads. To this end, detailed Finite Element (FE) models of CFS back-to-back channel members were developed featuring material non-linearity and geometric imperfections, and validated against the results of experimental tests. The validated FE models were then employed to carry out a comprehensive parametric study to investigate the effects of opening size and shape (square and circular web openings), as well as cross-sectional web slenderness on the strength, stiffness, failure mechanism, and ductility of CFS elements under shear forces. The results demonstrated that the shear strength of the CFS members can be significantly affected, up to 88 % and 30 %, by the size of openings and web slenderness, respectively. It was also found that while the ductility ratio of the CFS elements can be improved by increasing the opening size, elements with lower web slenderness showed less ductile behaviour. Based on the results of the parametric study, a practical design equation was developed for the shear strength of CFS members with web openings, and the predictions were compared with those determined by the AISI and other existing methods. Finally, a reliability analysis was performed within the framework of the European design standard.

A Review Paper on Finite Element Analysis on Lateral Torsional Buckling Behavior of I Beam with Web Opening Using ETABS Software

Abstract: The lateral-torsional buckling behavior of I-beams with web openings has been a topic of interest among structural engineers for many years. The presence of a web opening in the beam can significantly affect its strength and stiffness, making it more prone to buckling failure. Therefore, understanding the buckling behavior of I-beams with web openings is crucial for the design of steel structures. Finite Element Analysis (FEA) has become a widely used tool for investigating the behavior of structures under different loading conditions. In this study, FEA was used to analyze the lateral-torsional buckling behavior of I-beams with web openings. The software used for the analysis was ETABS, which is a widely used software for analyzing and designing buildings and other structures. The objective of the study was to investigate the effects of different web opening shapes, sizes, and locations on the buckling strength of the beam. The FEA simulations were validated using experimental data available in the literature. The study analyzed different types of web openings, such as circular, rectangular, and elliptical shapes, and various sizes and locations of the web opening along the beam span. The results of the study showed that the presence of a web opening significantly reduced the strength and stiffness of the I-beam, making it more susceptible to buckling failure. The location of the web opening had a more significant effect on the buckling behavior than its size and shape. The results of the FEA simulations were found to be in good agreement with the experimental data available in the literature, which validates the accuracy of the ETABS software in predicting the buckling behavior of I-beams with web openings

Resistance to Earhead Caterpillars in Finger Millet

Field experiment was conducted at the Zonal Agricultural Research Station, Vishweshwaraiah Canal Farm, Mandya during kharif 2018 and 2019, to assess the mechanism of resistance like earhead shape and colour of finger millet genotypes against earhead caterpillars viz., Cryptoblabes angustipennella (Hampson), Somena scintillans (Walker), Helicoverpa armigera (Hubner), Spodoptera frugiperda (J E Smith), Archips micaceana (Walker), Nola analis (Wileman and West), Cydia sp., Pyrausta phoenicealis (Walker), Corcyra cephalonica (Stainton) and Stathmopoda sp. Among the 230 genotypes screened against earhead caterpillars, droopy/lax and open earhead shape genotypes were completely free from the larval incidence. On the other hand, a large number of genotypes with purplish earheads showed a lower larval incidence (2.02 larvae/ earhead), indicating their higher level of resistance.

Nanomaterials Based on Collaboration with Multiple Partners: Zn3Nb2O8 Doped with Eu3+ and/or Amino Substituted Porphyrin Incorporated in Silica Matrices for the Discoloration of Methyl Red.

Designing appropriate materials destined for the removal of dyes from waste waters represents a great challenge for achieving a sustainable society. Three partnerships were set up to obtain novel adsorbents with tailored optoelectronic properties using silica matrices, Zn3Nb2O8 oxide doped with Eu3+, and a symmetrical amino-substituted porphyrin. The pseudo-binary oxide with the formula Zn3Nb2O8 was obtained by the solid-state method. The doping of Zn3Nb2O8 with Eu3+ ions was intended in order to amplify the optical properties of the mixed oxide that are highly influenced by the coordination environment of Eu3+ ions, as confirmed by density functional theory (DFT) calculations. The first proposed silica material, based solely on tetraethyl orthosilicate (TEOS) with high specific surface areas of 518-726 m2/g, offered better performance as an adsorbent than the second one, which also contained 3-aminopropyltrimethoxysilane (APTMOS). The contribution of amino-substituted porphyrin incorporated into silica matrices resides both in providing anchoring groups for the methyl red dye and in increasing the optical properties of the whole nanomaterial. Two different types of methyl red adsorption mechanisms can be reported: one based on surface absorbance and one based on the dye entering the pores of the adsorbents due to their open groove shape network.

A comparative account of the embryonic lineage and gonad development in two species of Rhabditidae (Nematoda)

ABSTRACT Nematodes serve as excellent models for developmental studies, with a good number of favourable properties. The family Rhabditidae is a paraphyletic group of bacterivorous nematodes showing diversity in the structure of gonads, mode of reproduction, cleavage pattern, etc. In the present paper, two species of Rhabditidae, namely Mesorhabditis paucipapillata Paetzold, 1955 and Cephaloboides anisospiculus Tahseen et al., 2017, with monodelphic and didelphic types of gonads, respectively, were selected for a comparative analysis of the embryonic patterns and trends in gonad development. The cleavage patterns of the early cell lineages were observed to vary considerably with the division of EMS after three consecutive divisions in the AB line in C. anisospiculus. The patterns of gonad development differed, with the number of branches being the key factor in determining the shape and orientation of the primordium; in contrast, vulva formation largely depended on the position and shape of the vulval opening.

THE EFFECT OF PUBLIC FACADE CHARACTERISTICS ON CHANGING PEDESTRIAN BEHAVIORS

The facades that define the public open space shape the pedestrian behavior by affecting the visual perception of the pedestrians. In the literature on facade and human interaction, there are pioneering studies in the perspective of environmental perception, but there is a lack and method limitation on the effect of the facade on pedestrian behavior. For this reason, the research aims to evaluate pedestrian behaviors in two areas that are variable in terms of facades, together with video analysis and heat maps. Areas of similar typology in Istanbul’s Kadıköy district are compared because of the temporary exterior decoration of the historical candy store in case 1 during the New Year’s Eve. According to the research findings, there is a significant difference between the quantity of pedestrians exhibiting stagnant and flowing behaviors and the distribution of these pedestrians in the space. In addition, the subcategories of fluid and static behavior in evening and day conditions also reveal interpretable results regarding the front. The results of the research reveal that the facade features of the public space significantly affect the pedestrian behavior, and therefore this issue should also gain importance in the future of public space design.

A Study of the Anatomy of the Eustachian Tube for Its Surgical Approach in Otorhinolaryngology

The eustachian tube (ET) is a connection between the nasopharynx and the middle ear behind the inferior nasal concha. It plays an important role in regulating air pressure across the tympanic membrane for proper transmission of sound. The pharyngeal opening of the tube is an important landmark for endoscopic evaluation in patients suffering from chronic otitis media and is also an important anatomical landmark for the transnasal approach to the infratemporal fossa. Hence, the study was done to locate the position of the pharyngeal opening of the ET in relation to various important anatomical landmarks. Hundred (50 right and 50 left sides) adult (60-80 years) formalin-fixed sagittal sections of head and neck specimens were taken for the study, which was obtained during the undergraduate teaching program. The shape, size, and position of the pharyngeal opening of the ET were noted. The distance between the pharyngeal opening of the ET and various anatomical landmarks was measured with the help of the digital Vernier caliper. The mean and standard deviation of all the parameters were calculated and tabulated. In the present study, a slit-like shape was the most common shape of the pharyngeal opening, present in 62 out of 100 specimens. The difference between the anteroposterior length and vertical height of the two sides showed a statistically significant difference. The present study will help to locate the position of the pharyngeal opening of the ET during otorhinolaryngological evaluation for performing various surgeries in the middle ear.

Analytically Design and Tested the Flat Slab with Drop and Without Drop under Punching Shear Strength Considerations

Abstract: Two types of flat slab are tested one having drop and another having no drop. Shape of openings-(circular, rectangular and square) having sizes of openings (500mm dia, 400mm x 500mm, 445mm x 445mm) respectively. Dimension of slab panel is (6000mmx 6000mm x 220mm) and the drop having size (3000mmx 3000mm). size of column – (500mmx 500mm). The provision of location of openings is at center of the slab panel. Software CSI Safe16 is used to analytically design and check the result. End result is based on punching shear value, deflection, Maximum shear force and maximum bending moment.

Intelligent evaluation of impact damage for subsea protective facilities with asymmetric openings

In this paper, the influence of the structural parameters of subsea protective devices with asymmetric openings is studied through intelligent damage assessments. Moreover, three back propagation (BP) neural networks, the Levenberg‒Marquardt (LM) algorithm, Bayesian regularization (BR) algorithm and scaled conjugate gradient (SCG) algorithm, are selected to evaluate the damage to subsea protective facilities. Finite element models of subsea protective facilities without openings, square subsea protective facilities with openings and circular subsea protective facilities with openings are established, and finite element analysis is carried out to establish the database training algorithm. The accuracy of the database is ensured through testing to verify the finite element method. The influence of the opening, opening shape and structural damage on the damage assessment is analysed to find the most suitable intelligent damage assessment algorithm for subsea protective facilities with asymmetric openings. The results show that the opening will increase the error of damage identification, and the square opening will increase the maximum error. Meanwhile, structural damage will increase the damage evaluation error of subsea protective facilities with asymmetric openings but will reduce the damage stress evaluation error of subsea protective facilities without openings. In addition, the identification error of the BR neural network algorithm for each working condition, which is suitable for intelligent damage identification of subsea protective facilities, is very low.

Influence of the Shape and Proportions of Window Openings and the Presence of External Window Wall Structures on the Luminous and Insolation Environment in the Premises

The article deals with issues related to ensuring the required parameters of the luminous environment in the premises of civil buildings with a lateral system of daylighting in them while simultaneously ensuring the necessary duration of insolation in these premises. It is noted that in modern architectural and construction practice, these requirements can be met, in particular, through the use of various shapes and proportions of window openings, as well as through the use of window wall structures of various types. On the basis of the conducted research, it was concluded that this approach is promising, since it fully meets modern requirements for the creation of energy-efficient buildings based on passive (natural) methods that ensure a normal microclimate of the internal environment in the premises solely due to specific architectural and structural design techniques.

Additive manufacturing for plastic extrusion die tooling: A numerical investigation

Additive Manufacturing (AM) has become commonplace to iterate concepts and realize products in different industries. The maturation of AM has made it a viable alternative to Subtractive Manufacturing (SM) processes, nevertheless there remain several unexplored opportunities. One of these is profile plastic extrusion tooling, which is typically produced at low volumes, can be complex in geometry, and could benefit from AM’s bottom-up process. Such manufacturing options raise the question of how one can evaluate whether AM should be considered as opposed to SM. The objective of this work is to establish a technology assessment method to evaluate which extrusion profile cases warrant consideration for AM. Results from Computational Fluid Dynamics (CFD) simulations of polymer flow through the flow channel are related to several applied parameters used by the extrusion industry. This provides a means to evaluate a tool’s design virtually before implementing in production. The technology assessment is performed on a U-Channel case, which is a common open profile shape with several product variations in industry. Results from this work indicate that there is no advantage of pursuing AM over an SM informed design for the specific U-Channel case used in this study. In addition, streamlining features alone do not necessarily lead to clear improvements, highlighting the need for technology assessment tools and methods to evaluate whether AM or SM should be implemented. This work lays the foundation for evaluating which extrusion profile cases warrant consideration for an AM process.