Bar Dimensions Research Articles

Removal enhancement of persistent basic fuchsin dye from wastewater using an eco-friendly, cost-effective Fenton process with sodium percarbonate and waste iron catalyst.

In this comprehensive investigation, we evaluate the efficacy of the Fenton process in degrading basic fuchsin (BF), a resistant dye. Our primary focus is on the utilization of readily available, environmentally benign, and cost-effective reagents for the degradation process. Furthermore, we delve into various operational parameters, including the quantity of sodium percarbonate (SPC), pH levels, and the dimensions of waste iron bars, to optimize the treatment efficiency. In the course of our research, we employed an initial SPC concentration of 0.5 mM, a pH level of 3, a waste iron bar measuring 3.5 cm in length and 0.4 cm in diameter, and a processing time of 10 min. Our findings reveal the successful elimination of the BF dye, even when subjected to treatment with diverse salts and surfactants under elevated temperatures and acidic conditions (pH below 3). This underscores the robustness of the Fenton process in purifying wastewater contaminated with dye compounds. The outcomes of our study not only demonstrate the efficiency of the Fenton process but highlight its adaptability to address dye contamination challenges across various industries. Critically, this research pioneers the application of waste iron bars as a source of iron in the Fenton reaction, introducing a novel, sustainable approach that enhances the environmental and economic viability of the process. This innovative use of recycled materials as catalysts represents a significant advancement in sustainable chemical engineering practices.

Scale Models to Verify the Effectiveness of the Methods to Reducing the Vertical Bending Vibration of the Railway Vehicles Carbody: Applications and Design Elements

The purpose of this paper is to present applications and design elements of scale models of the carbody of railway vehicles integrated in experimental laboratory systems to verify the effectiveness of the methods to reduce vertical bending vibration of the carbody. In the first part of the paper, some applications of such experimental systems are presented, which include different scale models of the railway vehicle carbody. In the second part of the paper, the structure and dimensioning elements of a new demonstrative experimental system, specially designed by the authors of the present paper for testing the functionality of an original method of reducing the vertical bending vibrations of the carbody of railway vehicles, are presented. This method is based on an innovative approach that involves the use of a passive system consisting of two bars rigidly mounted on the longitudinal beams of the carbody underframe, having the role of opposing the bending of the carbody. The main element of the demonstrative experimental system is the scale model of the vehicle carbody, reduced to a beam, on which the two bars, called anti-bending bars, are mounted. For the dimensioning of the experimental model of the carbody and the anti-bending bars, original methodologies are developed in which several conditions are involved. In the case of the dimensioning of the experimental model of the carbody, the conditions refer to the convenient adoption of the scaling factor of the dimensions of the real carbody from the perspective of the practical realization of the experimental model of the carbody, ensuring the buckling stability of the demonstrative experimental system, achieving natural frequency of the vertical bending of the real carbody and avoiding the interference of the bounce vibration with the vertical bending vibration of the demonstrative experimental model of the carbody. The dimensions of the anti-bending bars are established from the condition that the vertical bending frequency of the experimental model of the carbody is outside the range of sensitivity of the human body to vertical vibration. Additionally, the natural frequency of the vertical bending vibration of the anti-bending bars must be chosen to avoid interference with the vertical bending vibration of the experimental model of the carbody. The effectiveness of the anti-bending bars in reducing the vertical bending vibration of the experimental model of the carbody is investigated with the help of numerical simulation results developed based on an original theoretical model of the experimental model of the carbody with anti-bending bars.

ПОЛЯРИЗАЦІЙНО ТА ЧАСТОТНО СЕЛЕКТИВНІ ХАРАКТЕРИСТИКИ ХІРАЛЬНОЇ ПОВЕРХНІ, ЩО СКЛАДАЄТЬСЯ З ПЕРІОДИЧНО РОЗТАШОВАНИХ ДІЕЛЕКТРИЧНИХ КВАДРАТНИХ СПІРАЛЕЙ

Subject and Purpose. The present study is concerned with the linearly polarized electromagnetic wave transmission through a chiral metasurface composed of periodically assembled square dielectric helices. We expect that the metasurface of the kind has a wider range of functional capabilities to transform a polarized wave into a cross-polarized one when compared to a similar metasurface composed of metal helices. Methods and Methodology. To find the scattering coefficients of the considered structure, the well-established method of integral functionals is followed. A set of volume integral equations in the vectorial form is solved for the equivalent electric and magnetic polarization currents of the analyzed periodic layer. A distinctive feature of the method is that the internal electromagnetic fields of the structure are initially found, whence the fields scattered by this structure are sought. The equations are discretized in terms of integral functionals related to the polarization currents and through the use of the double Floquet–Fourier series expansion technique. Results. It has been found that the metasurface transmission coefficients depend critically on the number of bars making the square helical particle. In the case of an even bar number, the chiral metasurface exhibits the same transmission coefficients for co- polarized field components in the event that linearly x- and y-polarized waves are incident. For cross-polarized field components, the transmission coefficients differ and can reach peak values at different frequencies. Finally, transmission coefficients of these polarizers have been investigated versus dimensions of helice-making bars. Conclusion. A wide variety of transmission properties observed in the metasurfaces make them particularly attractive for use in polarization converting and separating devices. The metasurface can feature dichroic asymmetric transmission and be used as a dichroic filter with polarization transformation. It can be put to use in differential phase sections and, also, as an effective dichroic cross-polarization converter (twist polarizer)

Method for calculating local bearing capacity of concrete under bond stress from reinforcement in straight anchor section

A pull-out test is performed on 30 concrete specimens to determine the effect of bond stress on the local bearing capacity. The parameters include the dimensions of the headed bars, strength grade of the concrete, embedded length of the reinforcement, and diameter of the reinforcement. The dimensions of the headed bars are 50 mm × 50 mm × 20 mm and 60 mm × 60 mm × 20 mm, and the strength grades of concrete are C30, C40, and C50. The diameters of the reinforcement are 25 mm and 32 mm and its embedded length is divided into five types in the test. The local bearing capacities of 30 concrete specimens are obtained, and three failure modes are observed in specimens. The different modes of failure primarily depend on the combined action of the shell structure and wedge of the concrete. The pull-out test results indicate that the local bearing capacity of concrete under headed bars increases with an increase in the embedded length of reinforcement and the strength grade of concrete, with an almost linear relationship. In addition, the local bearing capacity decreases with an increase in the relative protective-layer thickness of the concrete specimens. Finally, a calculation method is proposed for the local bearing capacity of concrete under the action of bond stress from the reinforcement in a straight anchor section. The calculations considered the relative embedded length and the relative protective layer thickness of concrete as independent variables and the ratio of the local bearing capacity of concrete to the bearing capacity of concrete under the headed bars as a dependent variable. This calculation method provides a theoretical basis for standard revision and engineering applications.

Control of river discharge on large‐scale estuary morphology

AbstractEstuaries are dynamic landscapes with complex bar and channel patterns formed by interactions between tidal and fluvial currents. River discharge dampens the tidal wave, enhances the ebb flow, and supplies sediment to the estuary. However, it is largely unknown how river discharge influences overall estuary morphology. The objective of the current study is to quantify the control of river discharge on bar and channel dimensions and sediment transport throughout the estuary. To this end, a long‐term and large‐scale Delft3D‐2DH estuary model was designed with a suite of model runs undertaken where discharge systematically varied. Results show that tide‐dominated estuaries with significant river discharge can develop towards a dynamic equilibrium with a constant tidal prism through adjustment of channel dimensions to accommodate the supplied river discharge. It is essential to account for this morphodynamic adjustment when considering the transition from tide‐dominated estuaries to aggrading river‐dominated estuaries. After this transition, the estuary evolution depends on the discharge‐to‐width ratio. Tidal prism either decreases with higher river discharge as the tidal flow is dampened and the estuary aggrades, or increases when the estuary widens as it adjusts to the increase in total discharge. Additionally, results show that a higher river discharge increases the difference between the limit of flood‐dominant sediment transport and the limit of flow reversal, which has important implications for the preservation of the tidal signal in the stratigraphy. Estuary dimensions and channel patterns can be described as a function of river and tidal discharge. These findings indicate that the dynamic spatial component in numerical models is crucial in predicting trends in long‐term estuary morphology as well as in inverse predictions from stratigraphy.

Physico-magnetic properties and dynamics of magnetite (Fe3O4) nanoparticles (MNPs) under the effect of permanent magnetic fields in contaminated water treatment applications

In this work, a modelling and experimental study was performed to understand the dynamic behaviour of magnetite nano-particles (MNPs) released in a water flow when subjected to an external magnetic field. MNPs physical and magnetic properties and their tendency to form aggregates were also investigated. A mathematical model was developed and applied using MNPs characterization and 3-D field maps generated by OPERA software, considering different magnet bar dimensions and particle aggregate sizes. Model was run to assess the MNPs trajectories, and the capture efficiency of a 10-cm height permanent magnet bar placed on the upper wall of a bench-scale rectangular duct in which MNPs are injected.Shorter MNPs trajectories were observed in the flow regions farther from the duct walls (lateral or bottom walls) where the frictional forces are lower. It is relevant to notice that the MNPs attraction is possible also in regions where the magnetic field is weak due to the high magnetic susceptibility of the system. MNP aggregate size significantly influences the particle dynamics with the trajectories of the larger particles converging more rapidly towards the magnet leading to their capture. However, this does not affect the global removal (∼90%) for aggregate diameters higher than 1.2 µm, demonstrating the general effectiveness of the investigated magnetic capture system, which is only partially influenced by the aggregate size variation. The comparison of modelled and experimental results shows the goodness of the developed model. Along with magnetic and aggregation studies and generated 3-D magnetic field maps, it represents a valid tool for future studies towards the development of practical applications for the magnetic removal of MNPs loaded by water contaminants.

Development and experimental testing of the technology for producing deformed bars of D16(T) alloy from continuously cast billets of small diameter with low elongation ratios

The article describes the development and pilot-scale testing of the technology for producing bars of the D16(T) aluminum alloy by radial-shear rolling from continuously cast billets with a diameter of 72 mm in several passes. The actual dimensions of rolled bars were within the ±0.16 mm tolerance for all bar diameters, which significantly surpasses the GOST 21488-97 requirements. According to the results of tensile tests, the values of ultimate strength, conventional yield strength, relative elongation and relative reduction were determined. Ultimate strength and relative elongation requirements specified by regulatory documents for the D16(T) alloy were met with a total elongation ratio of more than 4.2. In terms of plastic properties, the obtained bars surpass the GOST requirements by 2.1–2.5 times in the entire range of elongation ratios investigated starting from 2.07. At the same time, there is an increase in the relative elongation by 5.7–6.8 times in comparison with the initial cast state. The microstructure and morphology analysis conducted for secondary phases showed that with a decrease in the bar diameter (with an increase in the total elongation ratio), the average particle size of the α(AlFeMnSi) phase insoluble in the aluminum matrix decreases, which is a consequence of deformation processes developed during rolling. Additional grinding of inclusions during deformation processing can significantly reduce the possible negative effect of the insoluble phase on the mechanical properties of resulting bars, in particular on the plasticity properties. The microstructure analysis showed that bars after rolling and heat treatment are free from cracks, looseness, delamination, and other defects and meet the requirements of GOST 21488-97.

Depth‐limiting resistant layers restrict dimensions and positions of estuarine channels and bars

AbstractEstuaries comprise channels vital for economic activity and bars as valuable habitats. They are increasingly under human‐induced pressures (e.g. sea‐level rise and dredging), resulting in morphological changes that affect navigability, flood safety and ecology. Antecedent geology may strongly steer how estuary channels will adapt to these pressures, but is surprisingly absent in most models. Here geological data and a unique bathymetry dataset covering 200 years from the Ems‐Dollard estuary (Netherlands/Germany) were used to demonstrate how local resistant layers force the position and dimensions of confluences and bars on the scale of an entire estuary. These layers limit channel depth and consequently cause widening, resulting in mid‐channel bar formation and increased channel curvature. This could lead to unexpected estuary widening and may cause land loss in densely populated areas. With increasing channel volume (as may happen again under future sea‐level rise), resistant layers in the estuary's substrate become more exposed, which enhances their effects. Many systems around the world contain shallow resistant layers that potentially constrain estuary channel dimensions and steer bank erosion. This highlights that resistant layer effects are important to consider as part of mixed depositional processes in coastal environments. It is therefore necessary to globally account for the effects of inherited resistant layers in the possible response of estuaries to sea‐level rise and increased tidal penetration.

Spontaneous Symmetry Breaking: The Case of Crazy Clock and Beyond

In this work, we describe the crazy-clock phenomenon involving the state I (low iodide and iodine concentration) to state II (high iodide and iodine concentration with new iodine phase) transition after a Briggs–Rauscher (BR) oscillatory process. While the BR crazy-clock phenomenon is known, this is the first time that crazy-clock behavior is linked and explained with the symmetry-breaking phenomenon, highlighting the entire process in a novel way. The presented phenomenon has been thoroughly investigated by running more than 60 experiments, and evaluated by using statistical cluster K-means analysis. The mixing rate, as well as the magnetic bar shape and dimensions, have a strong influence on the transition appearance. Although the transition for both mixing and no-mixing conditions are taking place completely randomly, by using statistical cluster analysis we obtain different numbers of clusters (showing the time-domains where the transition is more likely to occur). In the case of stirring, clusters are more compact and separated, revealed new hidden details regarding the chemical dynamics of nonlinear processes. The significance of the presented results is beyond oscillatory reaction kinetics since the described example belongs to the small class of chemical systems that shows intrinsic randomness in their response and it might be considered as a real example of a classical liquid random number generator.

Assessing Storm Response of Multiple Intertidal Bars Using an Open-Source Automatic Processing Toolbox

Intertidal bars are common features of sandy beaches in meso- and macro-tidal environments, yet their behaviour under storm impact and subsequent recovery remain poorly documented. Intensive surveys provide valuable information; however, it takes time to process the vast amount of data. This study presents the morphological response of a multibarred macro-tidal beach along the Belgian coast after a severe storm that happened on 8–12 February 2020, and to develop and apply an oPen-source Raster prOcessing Toolbox for invEstigation Coast intertidal bar displacemenT (PROTECT) in Python for automated bar extraction. This toolbox was applied to the digital surface models of pre- and post-storm airborne LiDAR surveys of a multibarred intertidal beach. The PROTECT toolbox is capable of detecting the position and elevation of intertidal bars accurately. The uncertainty in the elevation characteristics of the bars induces an error in the elevation dimension of 0.10 m. Using the toolbox, the results showed that the intertidal bars changed in term of variations in bar number, dimensions and shape across the storm event. Overall, the storm significantly eroded the dune and the upper-beach zone with a sand loss equivalent elevation decrease of −0.14 m. This was followed by a continuous and full recovery after 9 months under fair weather conditions. In contrast, the sand budget in the intertidal zone did not change over the entire monitoring period although the bars showed significant morphological change. Applying the PROTECT toolbox on high-resolution 3D topographic datasets allows to increase the temporal mapping resolution of intertidal bars from long-term (years) to short (storm events) time scales. Similar assessments at locations worldwide would allow the improvement of our knowledge on the morphodynamical role of multibarred beaches and to forecast their evolution, thus contributing to manage future storm response and the progressively accelerating sea level rise.

Síntesis mediante algoritmos genéticos de mecanismos articulados de seis barras rígidas para prótesis de rodilla

Using the method of genetic algorithms, the synthesis process of a Watt I type six-bar flat mechanism is developed and applied to the design of a polycentric knee prosthesis to guarantee stability in the extension and total flexion phase of the knee during the knee. gait cycle of a person. Six precision points of the trajectory of the instantaneous center of rotation of the coupling link were selected, with a population of one thousand individuals formed with the lengths of links and angles of movement of the mechanism. The fitness function was obtained with the Freudenstein equation applied to two four-bar mechanisms that make up the prosthesis and the design restrictions were: minimum and maximum bar dimensions, Grashof criterion, angular relationships for ternary elements, transmission angle and instantaneous inactive joints.

Morphodynamic modeling the impact of large-scale embankment on the large bar in a convergent estuary

Many alluvial estuaries worldwide include an inside bar system, a large sediment deposit deeply stretched into the estuary. A good example of such a system is the large sediment deposit in the Qiantang Estuary, China. Its length and height reach 130 km and 10 m, respectively. Bathymetrical comparison reveals that the large bar has moved seaward by around 15 km over the last decades, probably related to the large-scale coastal embankment project. This motivated a quantitative investigation of the impact of estuarine planform on the inside bar development. The bar morphology is reproduced by means of an idealized 1-D morphodynamic model. Model results suggest that the bar movement is related to a decreasing tidal prism, increasing flood dominance in the lower reach and enhanced ebb currents in the upper reach, in response to the embankment. The timescale of the morphological response is only several years. The rapid response is related to the strong tidal currents and large sediment fluxes within the estuary. Sensitivity experiments show that the location and dimensions of the bar are related to the convergence length of the estuary. A decrease of the convergence length causes seaward movement and shortening and lowering of the bar. The bar dimensions also depend on the ratio between river and tidal discharges. When the ratio increases, the bar apex moves seaward and the elevation decreases. The bar movement has significantly influenced the tidal bore in the Qiantang Estuary.

Contribution To The Reduction Of The Ship’s Switchboard By Applying Sensor Technology

The paper discusses the contribution to energy efficiency by reducing the dimensions of the main switchboard (medium voltage or High Voltage – used on ship). Reducing the dimensions of the switchboards can be achieved by reducing the dimensions of the bus bars, while fully satisfying the conditions with regard to thermal and mechanical stresses. The same can be achieved by modifying some other components, such as the application of new technology for measuring current and voltage, using current and voltage sensors that fall into the category of completely new technological solutions. By replacing conventional measuring transformers (IT), compact and efficient sensor technology significantly contributes to reducing the dimensions and mass of switchboards, which ultimately contributes to energy efficiency. Previous applications, the possibility of improving existing solutions, especially in applications in marine power systems, and new technological solutions that contribute to the efficiency of the marine power system using the Rogowski coil sensor and voltage divider voltage sensors are also considered.

The influence of river point bars on flood hydraulic using geometric model

Points bar formation has an important role to changing the hydraulic behavior during floods. In this study, topographic maps at 1:1000 scale for 40 km. given reach of river channel were used in HEC-GeoRAS and HEC-RAS softwares to simulate the geometric features and hydraulic behavior. The hydraulic behavior of Haraz river located in northern Iran, with 25 years of flood data was simulated in two scenarios of present channel conditions and without any point bar. Therefore, the effects of point bars were assessed on flood flow depth and zone, flow velocity and also water shear stress. The results indicated that the formation of point bars causes the flow resistance, its direction to the banks, accelerates erosion and increases the depth of flood. Also, point bars have increased the flood zone by reducing the flow capacity in a cross section of the river channel. Additionally, the increase in flow depth, flood zone, and water shear stress on the channel buffers were estimated 33.33, 95.57, and 66.67%, respectively. These changes are depending on the dimensions of point bars and the rate of flow reduction in a cross section of the channel given reach.

Bond behaviour of recycled aggregate concrete with basalt fibre-reinforced polymer bars

The combination of recycled aggregate concrete (RAC) and fibre-reinforced polymer (FRP) bars can effectively avoid corrosion. Bond performance is an important factor affecting the bearing capacity of RAC structures reinforced with FRP bars. In this study, the effects of the contact interface, concrete type, bar dimension, and surface shape of FRP bars on the bond performance of 39 pull-out specimens were investigated. The failure mode was analysed, and the evolution of damage at the interface between the concrete and basalt fibre-reinforced polymer (BFRP) bars was investigated. Moreover, the bond mechanism and the characteristics of the bond stress-slip curves were revealed. The effects of the design parameters on the bond strength, bond stiffness, residual bond strength, and slip were determined. A constitutive model was proposed to simulate the bond stress-slip relationship. Formulae to estimate the characteristic parameters were derived to develop the proposed model. The proposed model was shown to agree well with the experimental bond stress-slip curves. Finally, the development length of the BFRP bar-reinforced RAC structures was determined. The findings from this study could promote the application of BFRP bar-reinforced RAC structures and provide an experimental and theoretical basis for the design of their bond performance.

All-dielectric Metamaterial for Electromagnetically-induced Transparency in Optical Region

Metamaterial (MM) is emerging as a promising approach to manipulate electromagnetic waves, spanning from radio frequency to the optical region. In this paper, we employ an effect called electromagnetically-induced transparency (EIT) in all-dielectric MM structures to create a narrow transparent window in opaque broadband of the optical region (580-670 nm). Using dielectric materials instead of metals can mitigate the large non-radiative ohmic loss on the metal surface. The unit-cell of MM consists of Silicon (Si) bars on Silicon dioxide (SiO\(_{2}\)) substrate, in which two bars are directed horizontally and one bar is directed vertically. By changing the relative position and dimension of the Si bars, the EIT effect could be achieved. The optical properties of the proposed MM are investigated numerically using the finite difference method with commercial software Computer Simulation Technology (CST). Then, characteristic parameters of MM exhibiting EIT effect (EIT-MM), including Q-factor, group delay, are calculated to evaluate the applicability of EIT-MM to sensing and light confinement.

Use of an international experience of mechanical reinforcement bars splicing in Ukraine

The problematic of reinforcement bars splicing by overlap tying and by the way of welding is described, as well as alternative splicing by the mechanical compression couplers as a way of its solution. Lap splicing showed good results in structures with small nominal dimensions of steel bars, low rate yield strength and in buildings not higher than 15 floors. Welding is the more flexible method of steel bars splicing but its use brings to rising costs and complicity of construction work. The quality of welded splices depends on many factors mainly on the existing problems in welding process. The analysis of world construction practice shows a more reliable, technological and effective way of splicing reinforcement bars it means the use of connecting couplers i.e. mechanical rebar coupling. Successful international experience of applying mechanical steel bars splicing in USA, Japan, China, Kazakhstan, UAE, etc. is described. It must be noted that with the advance of the enactment of DBN V 2.6-98 and DSTU B V.2.6-156, standard acceptable methods of steel bars splicing in Ukraine are lap splicing, welded connections and mechanical splicing. General technical requirements of the connections of reinforcement were analyzed and systematized, as well as general advantages of mechanical splices were proved. Analysis of international and native regulations showed that in Ukraine it should be taken more strict requirements for mechanical splices. Methodology and test results of mechanical splices were covered. A number of regulation documents were developed as a result of large scale theoretical and experimental research of mechanical connections. The technology of coupling of reinforcement bars was applied at many construction projects as well as in seismic regions.

Use of an international experience of mechanical reinforcement bars splicing in Ukraine

The problematic of reinforcement bars splicing by overlap tying and by the way of welding is described, as well as alternative splicing by the mechanical compression couplers as a way of its solution. Lap splicing showed good results in structures with small nominal dimensions of steel bars, low rate yield strength and in buildings not higher than 15 floors. Welding is the more flexible method of steel bars splicing but its use brings to rising costs and complicity of construction work. The quality of welded splices depends on many factors mainly on the existing problems in welding process. The analysis of world construction practice shows a more reliable, technological and effective way of splicing reinforcement bars it means the use of connecting couplers i.e. mechanical rebar coupling. Successful international experience of applying mechanical steel bars splicing in USA, Japan, China, Kazakhstan, UAE, etc. is described. It must be noted that with the advance of the enactment of DBN V 2.6-98 and DSTU B V.2.6-156, standard acceptable methods of steel bars splicing in Ukraine are lap splicing, welded connections and mechanical splicing. General technical requirements of the connections of reinforcement were analyzed and systematized, as well as general advantages of mechanical splices were proved. Analysis of international and native regulations showed that in Ukraine it should be taken more strict requirements for mechanical splices. Methodology and test results of mechanical splices were covered. A number of regulation documents were developed as a result of large scale theoretical and experimental research of mechanical connections. The technology of coupling of reinforcement bars was applied at many construction projects as well as in seismic regions.

An Integrated Review of River Bars for Engineering, Management and Transdisciplinary Research

River training and river restoration often imply modifying the patterns and dimensions of bars, channels, and pools. Research since the 1980s has greatly advanced and matured our knowledge on the formation and behavior of river bars, thanks to field work, laboratory experiments, theoretical analyses, and numerical modelling by several research groups. However, this knowledge is not easily accessible to design engineers, river managers, and ecologists who need to apply it. This is mainly due to confusing differences in terminology as well as to difficult mathematical theories. Moreover, existing scientific publications generally focus on specific aspects, so an overall review of the findings and their applications is still lacking. In many cases, the knowledge achieved so far would allow minimizing hard engineering interventions and thus obtaining more natural rivers. We present an integrated review of the major findings of river bar studies. Our aim is to provide accessible state-of-the-art knowledge for nature-based bar management and successful river training and river restoration. To this end we review the results from analytical, numerical, experimental, and field studies, explain the background of bar theories, and discuss applications in river engineering and river restoration.

Monkey Bar Dimensions Associated with Pediatric Upper Extremity Fractures Show Deviations from United States Product Safety Commission Recommendations.

BackgroundMonkey bar injuries account for the majority of playground injuries, and 34% result in a fracture. Studies have shown that there has been no decline in the number of monkey bar injuries over several decades. Our goal was to focus on fractures of the upper extremity resulting from monkey bar injuries. Additionally, we set out to analyze the dimensions of the monkey bar apparatus on which the injury occurred and determine if they were compliant with those recommended by the United States (US) Product Safety Commission.MethodsA retrospective chart review of all upper extremity injuries seen in a large pediatric orthopedic practice in 2017 was conducted to find all monkey bar-related injuries. Data was collected including age at the time of injury, gender, and injury type. Families of the injured child were contacted to identify the exact location of the injury. On-site measurements were made of the monkey bar apparatus including height, the distance between grips, the circumference of the grip, and ground surface type.ResultsOf 1968 patients seen in 2017, there were 990 upper extremity injuries and 66 monkey bar injuries (98.5% fractures). The average age of those injured on monkey bars was 6.6 ± 1.9 years, 60.6% were males. The average height of the apparatus was 207.32 ± 16.59 cm (range: 176.53-254 cm), the average distance between grips was 35.30 ± 5.62 cm, and the average circumference of the grip was 9.83 ± 1.03 cm. All exceeded the recommended height for preschool children aged 4-5 years (152.4 cm), and 11 of the 30 (36.7%) exceeded this recommended height for school-age children (213.26 cm). For the distance between grips, 23 of the 30 (76.7%) exceeded the preschool recommendation (30.48 cm), and three of 30 (13.3%) monkey bars exceeded the recommendation for school age children (38.1 cm).ConclusionMonkey bar injuries continue to be a common source of upper extremity fractures among young children. There is a high rate of non-compliance with current recommended safety standards.