Bar Frame Research Articles

Impact of Inclination of Girders and Columns on the Effort and Stability of Flat Bar Frames.

The article describes a specific method of using innovative transverse systems of flat bar frames as structures forcing elastic shape transformations of nominally flat folded sheets into the forms of ruled shell roof coverings. An innovative method for parametric shaping these forms and arrangement of frames constituting structural systems of sheds with folded thin-walled roof coverings, taking account of the specificity of designing elastically transformed roof sheeting, was proposed. The proposed method for defining the loads of the considered frames supporting lower shelves of the folds of transformed roof sheeting, as loads distributed uniformly along the length of the upper chord of a roof frame girder, is also an innovative approach. The above unconventional premises result in the innovative topic of the research presented in terms of checking the impact of changing the shape of subsequent flat frames (intended for the construction of sheds roofed with the transformed sheeting) on the geometric and mechanical properties of the members of these frames. For the defined loads and the proposed parameterization of the frame forms, an innovative set of conditions was developed to optimize their performance, and then a theoretical analysis of the observed dependencies was carried out. This analysis was performed in an unconventional, novel way using section modules of the cross-sections of all members. The performed computer simulations confirmed the significance of changes in the inclination of girders and columns on the geometric and mechanical properties of the members. The obtained results are the basis and justification for simulations and tests in the scope of further modification of the form, loads, work, and methods of using various configurations of flat frames in constructions.

DESIGN DEVELOPMENT AND PERFORMANCE EVALUATION OF SOLAR POWERED SPRAYER WITH WATER LEVEL INDICATOR

Currently in Bangladesh farmers use hand operated sprayer or motorized sprayer in agricultural fields. Generally in the agricultural field, traditional or conventional techniques like shoulder mounted spraying system have been used because it is cheaper, easy to use and less costly. Continuous use of traditional energy resources will have high risk of rising in price and energy depletion. Now-a-days there is a great need for ‘’conservation of energy’’ and application of renewable energy. This paper presents the design, development and evaluation of a solar powered spraying system. The specific objectives of this research is to design and fabricate the solar powered sprayer by considering parameters like desired spraying rate, low weight, low cost, faster coverage of area and high field efficiency. A two-nozzle sprayer was fabricated with MS bar frame and 4-wheel trolley with water level indicator which runs on power source as a DC battery (12 volt, 8.2 Ah) via solar panel and runs by a DC motor (12 volt, 2A). The entire unit is portable and is operated by one labor. The design mainly eliminates the shoulder mounting sprayer setup which causes back pain, uses of fossil power which is non-renewable and hazardous and extensive use of manpower. The machine was compared to conventional sprayer and found more efficient. Pump efficiency almost 83.33% found for single nozzle and 93.33% for double nozzle and the sprayer is 58% time saving than manual sprayer. The operating cost of the machine was 802 Tk ha-1 . Also found capital recovery factor, capital consumption and annual cost of the solar operated sprayer were 0.26, Tk 1520 and Tk 41665, respectively.

Design of reinforced concrete truss systems in earthquake-resistant high-rise buildings

This study aims to find out how to plan the Reinforced Concrete Bar Frame Structure which includes the structure of columns and beams and their reinforcement to meet the design concept of capacity, namely strong columns and weak beams. In this study, it will be planned on the Nusa Putra Islamic Boarding School building which amounts to 3 floors using the Special Moment Resistant Frame System (SRPMK) in accordance with SNI-2847-2013 and SNI-1726-2012. The earthquake load used is Spectrum Response Analysis by taking into account three different types of soil conditions namely hard, medium and soft soils. Moment Resistant Frame System is a spatial frame system in which structural components and their joints resist forces acting through bending, sliding and axial action. The quality of the concrete material used is 25 MPa and the reinforcing steel material used 400 MPa threaded iron while the beam dimensions are 300 mm x 400 mm and the column is 500 mm x 500 mm. The results obtained on the beam structure in hard soil conditions Mu = -85.5012 kN (support for) 4D19; Mu = 42.7506 kN (pedestal under) used 3D16; and Mu = 30,2581 kN (in the middle span) used 3D16; on medium soil Mu = 92.0741 kN (support for) 4D19; Mu = 46.03705 kN (lower pedestal) used 3D16; and Mu = 59.4276 kN (center span) used 3D16 + 1D13; on soft soil Mu = -107,842 kN (upper support) 5D19 was used; Mu = 53,921 kN (pedestal under) used 4D16; and Mu = 63.4546 kN (center span) used 4D16; Axial force occurs in the main column due to the combination of the three types of soil is not too significantly different, on hard soil = 337,949 kN, medium soil = 339,785 kN, soft soil = 342,954 kN, so column reinforcement in all three uses 12D22

Orbital Ingredients for Cooking X-structures in Edge-on Galaxies

Abstract X-structures are often observed in galaxies hosting the so-called B/PS (boxy/peanuts) bulges and are visible from the edge-on view. They are the most notable features of B/PS bulges and appear as four rays protruding from the disk of the host galaxy and distinguishable against the B/PS bulge background. In some works, their origin is thought to be connected with the so-called banana-shaped orbits with a vertical resonance 2:1. A star in such an orbit performs two oscillations in the vertical direction per one revolution in the bar frame. Several recent studies that analyzed ensembles of orbits arising in different N-body models do not confirm the dominance of the resonant 2:1 orbits in X-structures. In our work, we analyze two N-body models and show how the X-structure in our models is gradually assembled from the center to the periphery from orbits with less than 2:1 frequency ratio. The most number of such orbits is enclosed in a “farfalle”-shape (Italian pasta) form and turns out to be non-periodic. We conclude that the X-structure is akin to the envelope curve of regions of high density caused by the crossing or folding of different types of orbits at their highest points, and does not have a “backbone” similar to that of the in-plane bar. Comparing the orbital structure of two different numerical models, we show that the dominance of one or another family of orbits with a certain ratio of the vertical oscillations frequency to the in-plane frequency depends on the parameters of the underlying galaxy and ultimately determines the morphology of the X-structure and the opening angle of its rays.

AlterG Anti-Gravity Treadmill Accuracy of Unloading Is Affected by Support Frame Height.

de Heer, HD, Kaufman, A, Repka, CP, Rojas, K, Charley, B, and Bounds, R. AlterG Anti-Gravity Treadmill accuracy of unloading is affected by support frame height. J Strength Cond Res 35(10): 2910-2914, 2021-The AlterG Anti-Gravity Treadmill uses air pressure to provide partial body-weight support (BWS), lowering impact forces and metabolic demand of walking and running. Users wear specialized shorts that zip onto a bag supported by a metal bar frame covering the treadmill. The frame is placed at hip height in positions numbered 1-9, adjusted up or down based on preference. Machine accuracy in providing BWS is important to achieve desired training effects, but it is unknown whether frame placement impacts accuracy. Twenty subjects (10 men/women) were weighed in 10% increments from 0 to 60% BWS with the frame at hip height (iliac crest), the "neutral" position, and reweighed with the frame placed up to 3 numbers above or below hip height. Although the machine displayed the same proportion BWS, placing the frame higher than the neutral position resulted in significantly more support, whereas placing the frame lower led to less support. At 10% BWS, placing the frame 3 positions higher resulted in 3% more support compared with the neutral position (13.1% BWS, p < 0.001) and 3 positions lower in 4.7% less support (5.3% BWS, p < 0.001). Deviances were greater with more BWS. At 60% BWS, 3 positions higher than neutral resulted in 71.2% BWS (11.2% more than expected, p < 0.001) and 3 below 48.1% BWS (12.9% below expected, p < 0.001), total 24.1% difference. These findings suggest that the position of the support frame significantly impacts the AlterG accuracy in providing BWS, with placement higher than hip height resulting in more support than displayed by the machine and lower placement resulting in less support.

Numerical Study of the Force Transfer Mechanism and Seismic Behavior of Masonry Infilled RC Frames with Windows Opening

Masonry infilled walls are widely used in reinforced concrete (RC) frams worldwide. However, infilled RC frame building failure is a common mode in destructive earthquakes. Further researcher is needed to bring insightful understandings into the behaviors of these structures. Therefore, this study investigates seismic parameters, ultimate tensile damage, and force transfer mechanisms in a reinforced concrete structure under in-plan load. For this purpose, the definitions and the relevant literature were reviewed. Then, an analytical software supporting an infill model was selected and described altogether with a particular modeling approach. Calibrating software results with those presented by Abdulhafez et al. (2014), the researchers designed a series of planer one-story one-bay reinforced concrete frames upon ACI 318M-14 Building Code. The seismic behavior of infilled frames were also studied using finite element method. Force transfer mechanisms in infilled frame with opening, which is one of the important items, was investigated in this study. Comparing the analysis outcomes with the bar frame, it was indicated that the ultimate load, stiffness, and toughness of the full in-filled frame were increased while the ductility was decreased. It was also revealed that the presence of opening in infilled frame decreased the ultimate load, stiffness and toughness corresponding full infilled frame. In addition, the increasing of opening size increased the reduction of the ultimate load, stiffness and toughness.

Numerical investigations of shape of the reflecting surface made of knitted mesh fabric being pulled on the curvilinear frame

This paper presents the surface shaping numerical investigations results of truss space constructions mesh reflectors, such as antennas and calibration and adjustment satellites. Shape-generating structure of mentioned constructions adds up to set of triangular facets, made in the form of spatio-curvilinear bar frames, bearing reflecting knitted mesh fabric pulled on it. This work proposes the algorithm of calculation of step-by-step reflecting mesh pulling on the bearing frame’s bars process, using finite elements method. Numerical execution of the developed algorithm involves for resolving the linear elasticity theory first-type boundary value problem, which implies integration of elastic body equilibrium equations without taking into account mass forces when kinematic boundary conditions are given. Analyzing when having done numerical calculations, it's possible to determine what grade obtained shapes of reflecting surfaces are precise with, and to find possible for developing variants of the antenna structure, which would allow to obtain the reflector surface shape with required accuracy by using flexible cables as a part of shape-generating structure. Comparing results of numerical investigations with experimental data received using full-scaled model of spherical calibration and adjustment satellite shows satisfactory qualitative and quantitative matching of both results.

Omnidirectional Malleable Ring Retractor: New Approach to Retraction During Carotid Endarterectomy

To resolve problems with retraction instruments in order to obtain shallow and flat operative field in procedures such as carotid endarterectomy, we developed a new malleable tin alloy omnidirectional retraction supporting (ORS) ring. The new ORS ring has an ellipse-shaped (major axis: 275 mm; minor axis: 192 mm) bar frame (4 mm× 6 mm). The bar has 22 equidistant outward protrusions (length, 12 mm; diameter, 2.5 mm). The frame is made of tin alloy with approximately 1% silver, which provides sufficient malleability to fit different cervical surgical approaches. Rubber bands ending with hooks are attached around the protrusions. The new ORS ring can be placed closer to the skin surface, and skin incision edges are horizontally retracted by the hooks attached in the desired direction. The hooks are repositioned in a stepwise fashion at deeper layers of the surgical wound following dissection for carotid artery exposure. The tin alloy ORS ring was used in 30 carotid endarterectomies. As this ring could be closely positioned in all cases, the real depth of the operative fields (with all instruments in place) was reduced by the omnidirectional horizontal retraction without interference with surgical manipulations. Working on the distal internal carotid artery, such as putting a tacking suture in place and arteriotomy closure, could be easily performed. The newly developed malleable tin alloy ORS ring can be a valuable instrument for the easy performance of surgery for cervical carotid lesions. Considering its advantages, it is better than conventional retractors and existing stainless steel ORS rings.

Development of tractor operated bund former-cum-packer for increasing resource productivity

In mechanized farm, bund is prepared by a bund former either operated by tractor or animals for irrigation purposes and also to demarcate the fields. Tractor operated bund formers are normally either disc -or mould board or forming board type. If bund is formed with the help of traditional bund former, however, shaping and packing of bunds is done manually using spade and feet. This activity is time consuming and labour intensive. To overcome the drudgery involve in these operations, a tractor operated bund former-cum-packer was designed and developed. An attempt is made for enabling the combined operations of bund forming and packing in single pass that can save fuel, time and other resources further. The bund former-cum-packer consisted of commercially available disc type bund former, rectangular tool bar frame, and packing unit (concentric cylindrical roller, drive shaft, conical discs, compressive shanks etc). The bund formed by bund former-cum-packer was field tested and found neither water seepage nor breakage of bund during flood irrigation. The field capacity with the equipment was 1.4 ha/h at tractor speed of 2.93 km/h in 2nd low gear. The bund former-cum-packer can reduce about 96% dependency on labour requirement for packing the bund. Overall use of the equipment is having potential to increase the resource productivity by 38 %.

Hercules and Wolf 630 stellar streams and galactic bar kinematics

We have identified the four most significant features in the UV velocity distribution of solar neighborhood stars: H1, H2 in the Hercules stream and W1, W2 in the Wolf 630 stream. We have formulated the problem of determining several characteristics of the central Galactic bar independently from each of the identified features by assuming that the Hercules and Wolf 630 streams are of a bar-induced dynamical nature. The problem has been solved by constructing 2:1 resonant orbits in the rotating bar frame for each star in these streams. Analysis of the resonant orbits found has shown that the bar pattern speed is 45-55 km/s/kpc, while the bar angle lies within the range 40-60 degrees. The results obtained are consistent with the view that the Hercules and Wolf 630 streams could be formed by a long-term influence of the Galactic bar leading to a characteristic bimodal splitting of the UV velocity plane.

A UNIFIED FRAMEWORK FOR THE ORBITAL STRUCTURE OF BARS AND TRIAXIAL ELLIPSOIDS

ABSTRACT We examine a large random sample of orbits in two self-consistent simulations of N-body bars. Orbits in these bars are classified both visually and with a new automated orbit classification method based on frequency analysis. The well-known prograde x1 orbit family originates from the same parent orbit as the box orbits in stationary and rotating triaxial ellipsoids. However, only a small fraction of bar orbits (∼4%) have predominately prograde motion like their periodic parent orbit. Most bar orbits arising from the x1 orbit have little net angular momentum in the bar frame, making them equivalent to box orbits in rotating triaxial potentials. In these simulations a small fraction of bar orbits (∼7%) are long-axis tubes that behave exactly like those in triaxial ellipsoids: they are tipped about the intermediate axis owing to the Coriolis force, with the sense of tipping determined by the sign of their angular momentum about the long axis. No orbits parented by prograde periodic x2 orbits are found in the pure bar model, but a tiny population (∼2%) of short-axis tube orbits parented by retrograde x4 orbits are found. When a central point mass representing a supermassive black hole (SMBH) is grown adiabatically at the center of the bar, those orbits that lie in the immediate vicinity of the SMBH are transformed into precessing Keplerian orbits that belong to the same major families (short-axis tubes, long-axis tubes and boxes) occupying the bar at larger radii. During the growth of an SMBH, the inflow of mass and outward transport of angular momentum transform some x1 and long-axis tube orbits into prograde short-axis tubes. This study has important implications for future attempts to constrain the masses of SMBHs in barred galaxies using orbit-based methods like the Schwarzschild orbit superposition scheme and for understanding the observed features in barred galaxies.

A vertical resonance heating model for X- or peanut-shaped galactic bulges

We explore a second order Hamiltonian vertical resonance model for X-shaped or peanut-shaped galactic bulges. The X-shape is caused by the 2:1 vertical Lindblad resonance with the bar, with two vertical oscillation periods per orbital period in the bar frame. We examine N-body simulations and find that due to the bar slowing down and disk thickening during bar buckling, the resonance and associated peanut-shape moves outward. The peanut-shape is consistent with the location of the vertical resonance, independent of whether the bar buckled or not. We estimate the resonance width from the potential m=4 Fourier component and find that the resonance is narrow, affecting orbits over a narrow range in the angular momentum distribution, dL/L ~ 0.05. As the resonance moves outward, stars originally in the mid plane are forced out of the mid plane into orbits just within the resonance separatrix. The height of the separatrix orbits, estimated from the Hamiltonian model, is approximately consistent with the peanut-shape height. The X-shape is comprised of stars in the vicinity of the resonance separatrix. The velocity distributions from the simulations illustrate that low inclination orbits are depleted within resonance. Within resonance, the vertical velocity distribution is broad, consistent with resonant heating caused by the passage of the resonance through the disk. In the Milky Way bulge we relate the azimuthally averaged mid-plane mass density near the vertical resonance to the rotation curve and bar pattern speed. At an estimated vertical resonance galactocentric radius of ~1.3 kpc, we confirm a mid-plane density of ~5x10^8 Msol/kpc^3, consistent with recently estimated mass distributions. We find that the rotation curve, bar pattern speed, 2:1 vertical resonance location, X-shape tips, and mid-plane mass density, are all self-consistent in the Milky Way galaxy bulge.

Nonlinear postbuckling analysis of frames with varying cross-section columns

A nonlinear static analysis is performed on an imperfect elastically supported two bar frame, which is subjected to a concentrated vertical load eccentrically at its joint. The column has a variable cross-section whereas the girder has a uniform cross-section. The variation ratio of the column cross- section is extensively investigated in combination with other geometric parameters (ratios of lengths and moments of inertia between column and girder) as well as loading parameters (loading eccentricity). Following a simplified procedure where the horizontal stiffness of the frame is modeled by a spring at the joint of the frame, it has been found that the developed axial force in the girder can be neglected (insignificant deviation of the exact results). Nonlinear finite element analysis is performed to verify the analytical results.

Application Research of Ground Penetrating Radar Detection on the Metal Structure in Tunnel Lining

As a nondestructive testing technology, GPR has been become one of the most important tools in quality inspection of tunnel lining at present. It is widely applied to tunnel disease detection, such as the holes, cracks, voids between tunnel lining and surrounding rock, and it is also used to determine the steel arch distribution and lining thickness of tunnel. Through the application of GPR in a highway tunnel lining detection, response characteristics of reinforced bar and steel arch frame are analyzed on radar maps under different frequencies of radar. Through identifying abnormal reflection in radar maps and interpreting its reason, the number and arrangement of reinforced bar and steel arch frame can be obtained. Comparing with the tunnel design, good results are obtained.

Dimensional Measurement by Projection of Locally Adapted Patterns

High‐strength structure components can be obtained by using an advantageously designed geometry. Examples are bar frame structures or organically shaped parts. Such components are challenging to manufacture due to their complex shape. This motivates the design of a new system for the 100% quality control of the geometric properties of such structures. Firstly, different measurement approaches and their usability for the measurement of high‐strength structure components are discussed. Then an optimized solution is suggested. A pattern projection method is introduced where the patterns adapt locally to the measured surface. This technique takes care of the special properties of high‐strength structure components within the production process. The paper presents a method how to obtain a measuring speed that can cope with a high production frequency without breaking the flow of the parts. Furthermore, measuring can take place in an industrial environment because it is relatively tolerant to movements of a component being measured. Therefore, the measuring procedure is divided into two steps. Within the adaptation‐step the luminescence and the resolution of the projected pattern is adapted to the object to be measured. The actual picture is taken and calculated in a second step in order to be robust to vibrations. The result of this measuring procedure is an optimized point cloud of several million points. The paper concludes with a description of the data processing procedures necessary in order to evaluate the correctness of the measured structure.

A study on ranked bidirectional evolutionary structural optimization (R-BESO) method for fully stressed structure design based on displacement sensitivity

Evolutionary Structural Optimization(ESO) method is well known as one of several topology optimization methods and has been applied to a lot of optimization problems. While ESO method evolves the given model into an optimum by subtracting several elements, in AESO method elements are added in a previous step of the evolutionary procedure. And in BESO(Bidirectional ESO) method, some elements are either generated or eliminated from a previous model of evolutionary procedure. In this paper, Ranked Bidirectional Evolutionary Structural Optimization(R-BESO) method is introduced as one of the topology optimization methods using an evolutionary algorithm and is applied to several optimization problems. The method can get optimum topologies of the structures throughout fewer iterations comparing with previous several methods based on ESO. R-BESO method is similar to BESO method except that elements are generated near a candidate element according to the rank calculated by sensitivity analyses. The displacement sensitivity analysis was adopted by the nodal displacements of a candidate element in order to determine a rank on the free edges for two dimensional model or the free surfaces for three dimensional model. In this paper, R-BESO method is proposed as another useful design tool like the previous ESO and BESO method for the two bar frame problem, the Michell type structure problem and the three dimension short cantilever beam problem, which had been used to verify reasonability of ESO method family. For the three dimensions short cantilever beam problem an optimized topology could be obtained with much fewer iterations with respect to the results of other ESO methods.

Reduction of air inflows in condensers of 200-MW power units

Results of updating the reducer between the LPC and the condenser involving removal of lens compensators and stiffening of the bar and rib frames are presented. Air inflows into the vacuum system through cracks in welded joints of flexible elements with total welded length of 240 m are lowered considerably by replacing them by stiff sheet structures. Computations of the thermal and stress-strain states of the system are performed.

Displaced fracture through the anterior atlantal synchondrosis

In the acute setting, accurate radiological interpretation of paediatric cervical spine trauma can be difficult due to a combination of normal variants and presence of multiple synchondroses. We present a rare case of a fracture through the anterior atlantal synchondrosis in a paediatric spine. A five-year-old boy, who fell backwards onto the top of his head while swinging across on a monkey bar frame, presented with neck pain, cervical muscle spasm and decreased right lateral rotation and extension of his neck. Computed tomography showed a displaced diastatic fracture through right anterior atlantal synchondrosis. There are only 12 cases of paediatric C1 fractures reported in the world literature. The importance of considering this diagnosis in the appropriate clinical setting, and the normal variants in the paediatric atlas that can cause diagnostic dilemma to the interpreting radiologist, are discussed in this case report.

A numerical code for lay-out optimization of skeletal structures with sequential linear programming

This paper discusses a new Sequential Linear Programming (SLP) algorithm denoted as LESLP (Linearization Error Sequential Linear Programming). The new algorithm implements an advanced strategy to choose the move limits which are defined by limiting the difference between the original nonlinear problem and its linearized counterpart. Besides, LESLP includes a trust region model to increase the design freedom and to improve the overall efficiency of the optimization process. LESLP is tested in five lay-out optimization problems of skeletal structures (i.e. bar trusses and frames) where the objective is to minimize the weight of the structure. It is obviously intended that the objective function does not require structural analysis. The new algorithm is compared to other SLP based techniques and globally convergent optimization methods like Sequential Quadratic Programming (SQP). Results indicate that LESLP is competitive with recently published algorithms and commercial softwares. Also, the new algorithm is robust with respect to starting designs.

Order and chaos in the local disc stellar kinematics induced by the Galactic bar

The Galactic bar causes a characteristic splitting of the disc phase space into regular and chaotic orbit regions which is shown to play an important role in shaping the stellar velocity distribution in the Solar neighbourhood. A detailed orbital analysis within an analytical 2D rotating barred potential reveals that this splitting is mainly dictated by the value of the Hamiltonian H and the bar induced resonances. In the velocity plane at fixed space position, the contours of constant H are circles centred on the local solid rotation velocity of the bar frame and of radius increasing with H . For reasonable bar strengths, the contour corresponding to the effective potential at the Lagrangian points marks the average transition from regular to chaotic motion, with the majority of orbits being chaotic at . On top of this, the resonances generate an alternation of regular and chaotic orbit arcs opened towards lower angular momentum and asymmetric in u for space positions away from the principal axes of the bar. Test particle simulations of exponential discs in the same potential and a more realistic high-resolution 3D N -body simulation reveal how the decoupled evolution of the distribution function in the two kind of regions and the process of chaotic mixing lead to overdensities in the chaotic part of the disc velocity distributions outside corotation. In particular, for realistic space positions of the Sun near or slightly beyond the outer Lindblad resonance and if u is defined positive towards the anti-centre, the eccentric quasi-periodic orbits trapped around the stable orbits -i.e. the bar-aligned closed orbits which asymptotically become circular at larger distances -produce a broad regular arc in velocity space extending within the zone, whereas the corresponding region appears as an overdensity of chaotic orbits forced to avoid that arc. This chaotic overdensity provides an original interpretation, distinct from the anti-bar elongated quasi-periodic orbit interpretation proposed by Dehnen ([CITE]), for the prominent stream of high asymmetric drift and predominantly outward moving stars clearly emerging from the Hipparcos data. However, the most appropriate interpretation for this stream remains uncertain. The effects of spiral arms and of molecular clouds are also briefly discussed within this context.