Suspension Wires Research Articles

Case Report: Management of pediatric Le Fort and mandibular fracture with a modified cap splint

Pediatric facial fractures are rare and make up 5–15% of all facial fractures. The low incidence of facial fractures among children is due to physiological and environmental factors such as greater resilience of the pediatric skeleton, higher bone to tooth ratio, direct parental supervision and limited outdoor activity.1 In children of 5–10 years of age nasal fractures are by far the most frequent (58.6%), followed by mandibular fractures (21.5%). Orbital (9.5%), frontal (5.1%), and midfacial (3.8%) fractures are next in frequency2. Le Fort fractures are very rare in children, and there is a paucity of literature presenting their frequency and characteristics. In the mandible condylar fracture is the most common (38.9%) followed by angle (20.6%), parasymphysis (18.3%), body (15.3%) and symphysis (5.3%).3 Facial fractures are more common in boys, though this varies greatly from 1.1:1 to 8.5:1.4 The majority of facial fractures in children result from falls (7.8–48%) and sports-related injuries (4.4–42%).5 In primary or mixed dentition, the placement of internal fixation hardware is challenging due to the risk of injuring unerupted permanent tooth follicles. The use of resorbable plates and screws offer a potential solution to the growing pediatric facial bone as the standard titanium fixation systems carry the risk of translocation, growth restriction, and dental injury. Dental splinting or suspension wires can also be used in place of direct plating. Fortunately, mild malocclusion at this age has the potential to be improved through bony remodeling, the eruption of permanent dentition, compensation of the mastication mechanism, and posttraumatic orthodontia.6 Accordingly, the goal of treatment is to restore the underlying bony architecture to its preinjury position in a stable fashion with minimal residual functional and esthetic impairment.

Development of Structural Design Method for Twisted Wires Suspension

Copper alloy suspension wires are used in the optical pickups and image stabilization mechanisms of mobile cameras. The durability of suspension wires used in mobile cameras is greatly affected by the increase in the weight of the lens assembly as makers improve the image quality of the camera. Therefore, the durability of the wire needs improvement. In this study, the stress reduction effect of twisted suspension wires was investigated using finite element method (FEM) analysis. In addition, a practical equation was obtained to facilitate the structural design. From this study, the following conclusions were obtained. In contrast to the conventional single-wire structure, the twisted wire structure enables a significant reduction in the stress generated while maintaining the stiffness. A simple formula that approximates the results of many FEM analyses was developed to enable rapid product design.

Typhoon-Induced Failure Process and Collapse Mechanism of Super-Large Cooling Tower Based on WRF-CFD-LS/DYNA Nesting Technology

There have been several cases of large cooling towers being damaged by wind in history. A typhoon has the characteristics of a strong wind field energy and large shear wind speed. This paper simulates the entire collapse process of large hyperbolic cooling towers by the action of typhoons and refines the typhoon-induced failure mechanism for cooling towers. Firstly, based on WRF-CFD wind field downscaling technology, a fine simulation of the near-ground multiscale wind field produced by China’s strongest typhoon “Typhoon Rammasun” is performed to extract effective three-dimensional (3D) typhoon load input parameters. Then, by loading the obtained 3D wind load on the finite element model, a pseudo-dynamic analysis of the world’s tallest cooling tower “Luan Cooling Tower” is performed based on LS-DYNA explicit dynamic analysis, and the typhoon-induced collapse process is simulated. Finally, the stress distribution and distortions of the tower and the response time history of key units are compared and analyzed to determine the collapse mechanism. The process of collapse begins with large deformation of the windward surface of the tower throat, which shows folds in the range of 62° on both sides. Eventually, collapse occurs due to uncoordinated deformation. The collapse mechanism can be divided into a bending arch mechanism and a suspension wire mechanism.

Effects of spacing on flaming and smoldering firebrands in wildland–urban interface fires

Firebrand (ember) attack has been shown to be one of the key mechanisms of wildfire spread into wildland–urban interface communities. After the firebrands land on a substrate material, the ignition propensity of the material depends on not only the attributes (e.g. shape, size, and numbers) but also the distribution of the firebrands. To help characterize this process, this study aims to investigate the effects of gap spacing on the burning behaviors of a group of wooden samples. Experiments are conducted using nine wooden cubes, 19 mm on each side. These samples are arranged in a 3 × 3 square pattern on suspension wires and are ignited by hot coils from the bottom surface. The gap spacing (s) between the samples varies in each test (ranging from 0 to 30 mm). After ignition, the samples are left to burn to completion. The burning process is recorded using video cameras. Sample mass loss and temperatures are monitored during the flaming and smoldering processes. The results show that the flame height and the sample mass loss rate have non-monotonic dependencies on the gap spacing. When the gap spacing reduces, the flame height and the mass loss rate first increase due to enhanced heat input from the adjacent flames to each sample. When s ≤ 10 mm, flames from individual samples are observed to merge into a single large fire. As s further decreases, the air entrainment at the flame bottom decreases and the flame lift-off distance at the flame center increases, resulting in an increased flame height, decreased flame heat feedback to the solid samples, and a decreased mass loss rate. The decreased mass loss rate eventually leads to a decrease in the flame height as well. The gaseous flame height is correlated to the solid burning rate. The correlation generally follows previous empirical equations for continuous fire sources. For the smoldering combustion, compared to a single burning sample, the smoldering temperature and duration significantly increase due to the thermal interactions between adjacent burning samples. To help interpret the results of the burning experiments, thermogravimetric analysis is also performed in air and nitrogen, resulting in heating rates ranging from 10 to 100 K/min.

A pendulum with a broken cylindrical symmetry: normal modes and beats

A pendulum, which has the cylindrical symmetry around its suspension wire, has two degenerate normal modes. We break this symmetry by putting a small magnet in the pendulum body and by running the pendulum in the presence of an inhomogeneous magnetic field. The force due to the magnetic field gradient modifies the equilibrium position and the spatial derivatives of this force define the normal modes of the pendulum with two different oscillation frequencies. We describe this system theoretically and we test these results by a series of experiments. This system provides a classical analogue of the degenerate perturbation theory in quantum mechanics.

Research on-orbit temperature variation stability of the positioning accuracy of maintenance interface

The space telescope is running, which is influenced by the rapid temperature difference. The paper analyzes the stability of the space environment of the on-orbit maintenance interface. The influence of temperature changes on the positioning of the interface mechanism is studied. Based on the 3-2-1 kinematic positioning principle, a mathematical model is established, and the mathematical expression of the on-orbit positioning accuracy of the back-end module between the temperature change and the interface layout point is deduced, and the variation quantity and the displacement variation of the angle of the center point are derived. The results show that when the line of AB points coincides with the positioning axis of B point, the rotation angle of the back-end module in the plane composed of A, B, C three points is the smallest. Through the relationship between the four independent variables λ, μ, η, t and the change of the central point ∆E, it is concluded that when A, B, C three-point layout is obtained, to make the back-end module have the highest stability, the order of variable design should be η, t, λ and μ. The suspension wire system was used to build a ground microgravity simulation test rig. The gravity unloading and thermal stress tests were carried out by the balancing mass method. The thermal stress test results prove that the interface can realize kinematics positioning and complete the on-orbit thermal stress release.

On-chip torsion balances with femtonewton force resolution at room temperature enabled by carbon nanotube and graphene.

The torsion balance, consisting of a rigid balance beam suspended by a fine thread, is an ancient scientific instrument, yet it is still a very sensitive force sensor to date. As the force sensitivity is proportional to the lengths of the beam and thread, but inversely proportional to the fourth power of the diameter of the thread, nanomaterials should be ideal building blocks for torsion balances. Here, we report a torsional balance array on a chip with the highest sensitivity level enabled by using a carbon nanotube as the thread and a monolayer graphene coated with Al nanofilms as the beam and mirror. It is demonstrated that the femtonewton force exerted by a weak laser can be easily measured. The balances on the chip should serve as an ideal platform for investigating fundamental interactions up to zeptonewton in accuracy in the near future.

An alternative approach for measuring yield stress and its application in Carbopol microgel

An innovative experimental apparatus for the direct measurement of yield stress was conceived and realized. It is based on a torsion pendulum equipped with a magnetic dipole and a rotating cylinder immersed in the material to be investigated. The pendulum equilibrium state depends on the mechanical torque applied due to an external magnetic induction field, elastic reaction of the suspension wire, and shear yield stress. Experimental results are reported showing that the behavior of the pendulum rotation angle, in different equilibrium conditions, provides evidence of the yield stress presence and enables its evaluation by equilibrium equations. The dependence on time of the equilibrium approach was also studied, contributing to shed light on the relaxation effect in the transition from a fluid-like to solid-like behavior, as well as on the eventual thixotropic effects in non-Newtonian fluids. The validity of the proposed technique and related experimental apparatus was tested in aqueous Carbopol solutions, with different weight percentages. The linear procedure, combined with the effectiveness and reliability of the proposed experimental method, candidates it to be used for the study of peculiar behaviors of other yield stress complex fluid such as blood, crude waxy oils, ice slurries, and coating layer used in the food industry and also for fault sliding in geodynamics.

Practical test mass and suspension configuration for a cryogenic kilohertz gravitational wave detector

Designs for future gravitational wave detection facilities feature silicon test masses at cryogenic temperatures to reduce thermal noise and thermally induced aberrations. Designers call for operation at 123 K or close to 18 K to exploit the vanishing thermal expansion of crystalline silicon. The amount of absorbed heat that can be radiatively removed from the test masses is limited at these temperatures, forcing complex cooling scenarios to be considered, including conduction through suspension wires. This is particularly relevant for the kilohertz class of detectors that aim for extremely high circulating power, i.e., roughly a factor 20 more than the world record at the time of writing, to reduce quantum noise. We explore the impact of raising the test mass temperature and show that a dedicated kilohertz-band cryogenic instrument can do so without significant sensitivity penalty, thereby boosting the radiative cooling rate and allowing higher power operation with simpler suspensions. We also explore the implications of operating cryogenic broadband detectors at elevated temperatures. The work presented here was instrumental in the development of the Neutron Star Extreme Matter Observatory kilohertz-band gravitational wave detector design concept.

Diamagnetic levitation of a milligram-scale silica using permanent magnets for the use in a macroscopic quantum measurement

Verification of macroscopic quantum mechanics requires that the position measurement accuracy of mirrors of various mass scales reach the Standard Quantum Limit (SQL) derived from Heisenberg's uncertainty principle. At mg-scale, thermal noise of the suspension wire of the mirror is an issue to reach the SQL. We propose to use a magnetic levitation system consisting of permanent magnets and yokes, noting the fact that a silica mirror is diamagnetic, and have succeeded in the experimental verification to levitate a 0.1-1 mg silica mass. This is the first demonstration of the levitation system with this mass scale and this magnetic susceptibility scale using permanent magnets as far as we know. We also estimated major noise sources for a 0.1 mg silica mirror and found the noise level to be lower than the SQL at 400 Hz-18 kHz. In conclusion, the levitation system of a mg-scale mirror for the use in a macroscopic quantum measurement was realized.

Sustaining an obturator prosthesis with zygomatic suspension wires in a case of subtotal maxillectomy and insuffient ridge supported retention: A case report

Purpose: For making denture in maxillectomy cases is very difficult and challenging to get the retention tomake the denture stable in its position during functioning. This case report describes a clinical condition inwhich patient was treated with a maxillary obturator with zygomatic suspension wiring due to insufficientretention in the palate.
 Materials and Methods: A 63-year-old patient had gone to a subtotal maxillectomybecause following myofibroblastic sarcoma andwas issued with bilateral circum-zygomatic wiring hooksimmediately after surgery. The patient had less than a third of their alveolar ridge remaining and did notprovide sufficient retention on its own. The wires were used for the retention because natural retentioncould not get due to inadequate maxillary ridge. While the denture was being fabricated, a temporaryfeeding plate was provisioned to the patient. Counter hooks were implemented on the definitive upperdenture, posterior to molars, to attach to the zygomatic suspension hook. Final upper denture was furtherreinforced with denture adhesive on it. A lower denture was also fabricated for the said case followingconventional protocols of jaw relation determination.
 Results: The obturator provided with adequate sealand leak proof phonetics. The zygomatic wiring coupled with denture adhesive were sufficient to provideadequate retention.
 Conclusion: Zygomatic suspension wires coupled with counter hooked obturatorprosthesis provide rehabilitation of patients with palatal defects with inadequate maxillary arch forretention.However long-term repeated use of such wires might expose the patient to secondary infectionsand should be kept in consideration
 Clinical Significance: Circum-zygomatic suspension wiring providesufficient retention to sustain the upper obturator prosthesis in place. However, the retention was stillinadequate, so denture adhesives were used to make it more stable.
 Bangladesh Journal of Medical Science Vol.19(3) 2020 p.582-585

Subchronic administration of Parastar insecticide induced behavioral changes and impaired motor coordination in male Wistar rats

Parastar is an insecticide formulation of lambda-cyhalothrin and imidacloprid largely used for crop protection in North West Region of Cameroon. In the present study, we evaluated the behavioral activities and motor function of Wistar male rats after subchronic treatment with the pesticide formulation. To this end, three groups of adult rats were administered Parastar at doses 1.25, 2.49 and 6.23 mg/kg, respectively, for 35 days. A control group was included and received distilled water. At the end of the treatment, the animals were submitted to behavioral and functional tests (open field test, elevated plus maze test, light-dark box test, forced swimming test, tail suspension test, beam-walking test, grid suspension test and wire hang test) for estimation of anxiety, exploration, depression and motor coordination. Results revealed that Parastar, at the higher doses tested, 2.49 and 6.23 mg/kg, induced anxiogenic-like pattern behavior in rats in all behavioral assays including open field test (total distance moved, total lines crossed, frequency and total time in center square were all reduced), elevated plus maze (decreased total time spent in open arms and the number of entries in open arms of the elevated plus maze), and light-dark box (the dark box duration increased, while light box duration time and frequency of transition between dark and light box decreased). Treatment with 2.49 and 6.23 mg/kg Parastar increased the immobility time of animals in both forced swimming test and tail suspension test. The insecticide induced decrease in the distance traveled, foot slip and number of turns of animals in the beam walking test. Parastar also decreased the animal suspension time in both grid suspension grip-strength test and the wire hang test. Taken altogether, these results suggest that subchronic administration of Parastar at the doses of 2.49 and 6.23 mg/kg induced anxiety-like and depressive-like behavior as well as impaired motor coordination and muscle strength in male rats.

Developing the NIS solid density hydrostatic weighing system up to 20 kg

This paper presents a developed design and construction to improve the performance and increasing the density measuring capability of the previous Hydrostatic Weighing Apparatus (HWA-NIS) at the National Institute of Standards (NIS) up to 20 kg. The previous (HWA-NIS) has been constructed up to 10 kg on 2014. The 2-Positions mass handler in the previous (HWA) was developed with 4-Positions pentagon shape to be able to make handling for individual masses in a group at once, when transferring the traceability from the primary standard “the Silicon Sphere” to the standard masses in the density scale weighing process. The weighing pan in the previous (HWA) was developed with four suspension wires with a diameter of 0.3 mm each, leads to reduce the surface tension affect on the measurement uncertainty by factor four times. The density of the standard masses in the range from 2 kg up to 20 kg were measured with an improved expanded uncertainty from 0.150 kg/m3to 0.078 kg/m3respectively due to reducing the effect of surface tension via the developed design of the weighing pan.

СОВЕРШЕНСТВОВАНИЕ МЕТОДОВ ИСПЫТАНИЙ КОНСОЛЕЙ КОНТАКТНОЙ СЕТИ

Catenary cantilevers are key devices that maintain the spatial position of catenary suspension wires. They determine the catenary parameters and indicators, increase of the calculation accuracy of which requires the consideration for maximum number of factors that affect the work of cantilevers in conditions of operation. The paper includes the overview of methods for testing catenary cantilevers and considers methods and devices for studying friction in cantilever connection joints, including those that consider environment temperature. As a result, the authors propose an improved method of calculation of catenary suspension parameters that is developed on the basis of experimental research results, the use of which will increase the accuracy of adjustment of wires and ropes.

EXPERIMENTAL RESEARCH OF HYSTERESIS EFFECT OF WIRE AND ITS INFLUENCE ON WIRE-DRIVEN PARALLEL SUSPENSION MECHANISM

Due to the advantages of structural simplicity, large workspace and low inertia, wire-driven parallel suspension mechanism is widely used. An experimental study is carried out on the hysteresis effect of a suspension wire. Firstly, the mathematical model of hysteresis curve in a Wire-driven Parallel Robot (WDPR) is analyzed and the corresponding parameters of the model are identified through experimental data. Secondly, the influencing factors of hysteresis phenomenon are discussed through hysteresis experiments under different conditions. Then the influence of hysteresis effect on pose and aerodynamic parameter calculation of the model is analyzed. Finally, the magnitude of the influence is analyzed based on the parameters of a WDPR prototype. The results exhibit the influence of hysteresis effect on both the pose and aerodynamic parameter calculation through wire tensions, and the material of wire is also one of the factors that cannot be ignored in relation to the hysteresis. Furthermore, the influence of hysteresis effect, dominantly determined by the level of preload, can be ignored when the preload increases to a certain extent.

Automated Inspection of Railway Tunnels’ Power Line Using LiDAR Point Clouds

Transport networks need periodic inspections to increase their safety and improve their management. In the last few years, LiDAR (light detection and ranging) technology has become a tool for helping to create a precise database of almost any type of infrastructure. Mobile laser scanning (MLS) systems use a laser beam to collect dense three dimensional (3D) point clouds, which include geometric and radiometric data of the environment in which they are placed. In the context of this paper, a methodology for automatically inspecting the clearance gauge and the deflection of the aerial contact line in railway tunnels is presented. The main objective is to compare results and verify their compliance with the Spanish norm. The 3D data are provided by a LYNX Mobile Mapper System (MMS). First, the area is surveyed and then the obtained (3D) point cloud is classified into contact wire, suspension wire, and remaining points. Finally, the inspection of the railway’s power line is performed. The validation of the proposed methodology has been carried out in three different tunnel point clouds, obtaining both qualitative and quantitative results for points’ classification, together with the results of the measures performed.

Surgical versus conservative interventions for treating acromioclavicular dislocation of the shoulder in adults

Surgical versus conservative interventions for treating acromioclavicular dislocation of the shoulder in adults

An experimental study of the puffing and evaporation characteristics of acetone–butanol–ethanol (ABE) and diesel blend droplets

Puffing and evaporation characteristics of acetone–butanol–ethanol (ABE) and diesel blend droplet under different ABE contents and ambient temperatures were investigated experimentally by using droplet suspension method. Both thermocouple wire and quartz fiber wire were adopted in this experiment to realize the measurement of droplet temperature, and minimize the effect of suspension wire. The experimental results show that, adding ABE component in diesel results in the droplet puffing, and increasing of ambient temperature promotes droplet puffing. With the increasing of ABE content, the onset point of puffing decreases first and then increases, and the average expansion speed and the frequency of puffing increase first and then decrease. Thus, an optimal volume blend ratio exists for puffing, which is found to be around 40%–50% ABE content. The occurrence of puffing decreases the duration of transient heating phase, and promotes the evaporation in the fluctuation evaporation phase. Thus, the overall evaporation duration decreases first and then increases with the ABE content increasing due to the effect of puffing at higher ambient temperature.

Theoretical and experimental evaluation of electromagnetic induction from power line upon multi-points grounded conductors

Electromagnetic induction between power lines and telecommunication cables may cause physical injury of service personnel, and malfunction or quality degradation of telecommunication services. Therefore, the influence of electromagnetic induction on telecommunication cables has been studied since early 1900’s. However, due to a complicated configuration and multi-point connection to the ground, there were few studies on induction phenomenon to a suspension wires that support overhead telecommunication cable. In this paper, we have studied on induction phenomena upon multiple point grounded conductors, theoretically and experimentally. As a result, we confirmed that calculated and measured results are in good agreement with ideal conditions.

КОНТРОЛЬ НАГРЕВА ПРОВОДОВ КОНТАКТНОЙ ПОДВЕСКИ

КОНТРОЛЬ НАГРЕВА ПРОВОДОВ КОНТАКТНОЙ ПОДВЕСКИ