Beam Cross Research Articles

A physical restraint device to facilitate rehabilitation in critically ill patients

Physical restraints are widely used in hospitalized and critically ill patients, especially in intensive care unit (ICU), to prevent adverse events such as the accidental removal of various monitoring leads, therapeutic tubes, and self-injury or injury to others due to delirium and irritation. The existing restraint measures directly bind the upper limbs of the patients to the hospital bed, which often brings psychological harm to the patients and leads to disuse muscular atrophy. Early rehabilitation therapy can help improve the prognosis of patients,but it is difficult to be widely used in ICU due to being heavily dependent on nursing and rehabilitation physicians. A novel restraint device to facilitate rehabilitation training for critically ill patients was designed by the medical staff from the department of critical care medicine of Beijing Tiantan Hospital, Capital Medical University and obtained the National Utility Model Patent of China (ZL 2020 2 2492749.6). The device is mainly composed of a cross beam and a locking device whose two ends are connected by a rocker arm, an upper limb stopper and an upper body stopper. The upper limb and body restraint provide restrictions on the movement of the head, the upper limb, and the upper body. The angle limiter prevents the patient from pulling out the treatment tube by himself, and at the same time retains the ability to grasp the crossbar and rotate it, and the sliding block further increases the activity space, to meet the exercise of the patient's upper limb muscle strength. Carrying out physical rehabilitation training as early as possible during ICU treatment can relieve the patient's resistance to passive restraint, reduce the incidence of disuse muscle atrophy, eliminate the potential hidden dangers of medical disputes, and ultimately improve the prognosis of patients.

Experimental and numerical analysis of wrinkles influence on damage mechanisms and strength of L-Shape cross-ply composite beams

In this work, experimental and finite element (FE) analysis of L-shape cross-ply fiber-reinforced composite beams are carried out to investigate the effect of out-of-plane wrinkles on the interlaminar strength and competing damage mechanisms. L-shape laminates are fabricated with manufacturing and geometrical variabilities, cured in a temperature and pressure-controlled autoclave process, and mechanically tested under four-point-bending tests. An in-situ high-fidelity FE models are constructed based on in-plane micrograph images of beam cross sections. Explicit FE failure simulations are performed to study the effect of wrinkles and to differentiate among different failure modes. Simulation results show a reasonable agreement with the test data in terms of delamination onsets, matrix cracking and through thick strength. Combined delamination, matrix cracking and kinking pattern is significant in the specimens with visible out-of-plane wrinkle. While, in the specimen with no noticeable wrinkle, a major single delamination is observable leading to final failure. The competing damage mechanisms is highly dependent on the assumed fracture properties and in-situ-condition of finite element model, regardless of good agreement between simulated global mechanical response and test data.

Structural Performance and Engineering Application of a Long Lasting Weathering Steel Composite Bridge with Tubular Flanges

A study of the structural performance and engineering application of a long lasting composite bridge with tubular steel flanges was carried out. The flexural, shear and torsional resistance of high-performance composite girders with tubular flanges were analysed comparatively based on tests and finite element simulation. Based on the research and design rules achieved above, the first two typical composite girder bridges with rectangular tubular flanges using high-performance weathering steel have been constructed in China. The structural performances were compared of a composite girder bridge with tubular flanges and a composite girder bridge adopting traditional I-shaped steel girders. A long-term performance evaluation was conducted for a weathering steel composite bridge with tubular flanges, which included an in situ inspection and rating assessment of the patina and life cycle cost evaluation of the whole bridge. Learned from the application experience and evaluation results, weathering steel composite girder bridges with tubular flanges revealed superior long lasting structural performance including improved torsional stiffness and resistance, fewer web stiffeners and cross beams, fast construction, and easy and less maintenance during the in-service stage.

Strengthening of Fire Damaged, Light Weight, High Strength Reinforced Concrete Beam Using SIFCON Jacket

This study aims to extrapolate the behavior of lightweight (LECA) high strength concrete beams subjected to high temperatures. the LECA aggregate was utilized as coarse fraction in the reference mixture. a post development process in terms of jacketing the fire damaged beams with SIFCON materials layer was also investigated. In addition to the reference samples, various parameters of concrete beams and conditioning were conducted, namely, fire duration exposure, concrete cover, and SIFCON layer thickness. In details, two concrete cover thickness, half and one-hour fire duration exposure, and two SIFCON layer thicknesses were the main parameters in this study. the thermal gradient through the beam cross section was captured through installing thermocouples sensors embedded inside at various location. The physical and chemical properties were tested for all used materials in this study. Overall, fourteen concrete beam samples were tested for all the three phases (normal or reference, fire damaged samples, and post enhancement with SIFCON jacket). the level of comparison for the tested samples was focused on several parameters are; maximum shear load capacity and corresponded displacement, ductility index, cracking load, initial and secant stiffness, and energy absorption. The experimental test results under the scope of this research have shown significant improvement for the strengthened beams were observed compared with the damaged samples. Moreover, the results have cleared that the strengthened beams, in term of the mentioned indices were recovered as and comparable to the undamaged (reference beam), except the absorption energy. Where further studies and efforts have to be paid to overcome such issue.

Dynamic stress analysis of a metro bogie due to wheel out-of-roundness based on multibody dynamics algorithm

In metro vehicle systems, the dynamic stress and vibration of the bogie frame have a significant impact on the safety and reliability of vehicles. This study presents a fracture failure analysis of the bogie frame for the metro vehicle. The analysis consists of a bogie frame dynamic stress test, a wheel out-of-roundness (OOR) measurement and a vibration transmissibility test of the vehicle which is also used for operational modal analysis of the bogie frame. The field test result shows that the bending of cross beam combined with torsion of side beams(49.5 Hz) which are aroused by the wheel OOR mainly contribute to the fatigue failure of the bogie frame. To investigate the effect of wheel OOR on the fatigue failure of the bogie frame, the multibody system (MBS) model of the metro vehicle was developed. The MBS model accounts for the flexibility of the bogie frame and the nonlinearity of wheel-rail contact. Furthermore, the modal stress recovery method was adopted to study the dynamic responses of the bogie frame. The measured wheel OOR data is used to validate the efficiency of the model and investigate the characteristics of dynamic stress in time histories as well as frequency spectra. Moreover, the dynamic stress of fracture site in the bogie frame with consideration of ideal polygonal wear in radial deviation including different orders and variable amplitudes was investigated. The phase shift of wheel OOR between different wheels proves to be influential in the bogie frame vibration and thus the characteristics of dynamic stress change accordingly. The recommended limit values of wheel OOR amplitude are shown based on numerical results.

Computing Natural Frequencies and Mode Shapes of an Axially Moving Nonuniform Beam

Abstract The partial differential equation of motion of an axially moving beam with spatially varying geometric, mass, and material properties has been derived. Using the theory of linear time-varying systems and numerical optimization, a general algorithm has been developed to compute complex eigenvalues/natural frequencies, mode shapes, and the critical speed for stability. Numerical results from the new method are presented for beams with spatially varying rectangular cross sections with sinusoidal variation in thickness and sine-squared variation in width. They are also compared to those from the Galerkin method. It has been found that critical speed of the beam can be significantly reduced by nonuniformity in a beam's cross section.

Spin–Orbit Coupling within Tightly Focused Circularly Polarized Spatiotemporal Vortex Wavepacket

Spin–orbital coupling and interaction as intrinsic light field characteristics have been extensively studied. Previous studies involve the spin angular momentum (SAM) carried by circular polarization and orbital angular momentum (OAM) associated with a spiral phase wavefront within the beam cross section, where both the SAM and OAM are in parallel with the propagation direction. In this work, we numerically study a new type of spin–orbital coupling between the longitudinal SAM and the transverse OAM carried by a spatiotemporal optical vortex (STOV) wavepacket under tight focusing condition. Intricate spatiotemporal phase singularity structures are formed when a circularly polarized STOV wavepacket is tightly focused by a high numerical aperture objective lens. For the transversely polarized components, phase singularity orientation can be significantly tilted away from the transverse direction toward the optical axis due to the coupling between longitudinal SAM and transverse OAM. The connection between the amount of rotation and the pulse width of the wavepacket is revealed. More interestingly, spatiotemporal phase singularity structure with a continuous evolution from longitudinal to transverse orientation through the wavepacket is observed for the longitudinally polarized component. These exotic spin–orbit coupling phenomena are expected to render new effects and functions when they are exploited in light–matter interactions.

A MEMS Fiber-Optic Fabry-Perot Vibration Sensor for High-Temperature Applications

An extrinsic high-temperature fiber-optic Fabry-Perot vibration sensor based on MEMS technology is described and experimentally demonstrated. The sensitive unit consists of four cross beams with a central seismic mass batch-fabricated on a silicon wafer. The sensing head is fabricated by MEMS technology including dry etching, anodic bonding and dicing processing. And the optical fiber is intergrated in the sensing head by laser fusing. According to our calculation, the sensor has a resonance frequency of 10.008kHz. Experimental results indicated that the sensitivity of the sensor from 2g to 22g, with the frequency of 200Hz, was 2.48 nm/g at 20°C and can work stably at 400°C. The nonlinearity of the sensor was evaluated from 20°C to 400°C and the max nonlinear error was 1.88% at 300°C. In addition, the temperature drift and temperature crossed sensitivity of the sensor agreed well with the theoretical analysis. We believe this proposed MEMS vibration sensor has a wide engineering high-temperature application prospect.

Cracks in single-layer and multi-layer concrete beams

In the study of cracking of concrete beams, cracks are formed and devel-oped depending on many different parameters: size of beam cross section, reinforced concrete material, effective load, calculation method, testing methods, etc. however, single-layer and multi-layer concrete beams, there are additional parameters that affect the formation and development of cracks with the participation of steel fibers in concrete and changes in content of steel fibers in concrete. With normal concrete beams that need to be repaired due to damage during use, the steel fiber concrete layer is poured over or be-low the normal concrete layer, forming laminated beam structure. Multi-layer beam structure has been studied in various forms of static and dynamic problems. However, in this study, the authors considered the formation and development of cracks, the load began to be cracked, the load began to be damaged and the order of the cracks appearing in single-layer and multi-layer steel fiber concrete beams both in testing method and ANSYS numeri-cal simulation method, in which, considering the nonlinearity of materials with a size of 0.15×0.2×2.2m single layer beam and a size of 0.15×0.3×2.2m double layers beam, in the case of steel fiber concrete layer is below the normal concrete layer.

Advanced scanning electron microscopy techniques for structural characterization of zeolites

Chemical etching after Ar ion beam cross sectioning enables the formation of zeolite internal nano structures to be observed directly using a newly developed highly sensitive scanning electron microscope.

Vibration Characteristics Analysis and Structure Optimization of Catenary Portal Structure on Four-Wire Bridge

The portal structure is the support equipment in the catenary, which bears the load of contact suspension and support equipment. In practical work, with the change of external forces, the support equipment bears complex and changeable loads, so it has higher requirements for its reliability and safety. In order to study the dynamic characteristics of catenary portal structure on continuous beam of four-way bridge, taking the catenary portal structure on Dshaping four-way bridge as the research object, the portal structure simulation model of bridge-network integration was established in Midas Civil. The maximum point of deformation and stress was determined by finite element analysis of catenary hard span equipment, and the frequency and mode of natural vibration of hard span were obtained by modal analysis. Secondly, through the field dynamic stress acquisition test, combined with the results of finite element analysis, the fault location is determined, and the vibration characteristics are analyzed. Finally, based on the results of modal analysis and vibration analysis, the method that the vibration of portal structure beam is affected by structural stiffness and vibration frequency amplitude is proposed. The torsional vibration of the portal structure beam was suppressed by increasing the stiffness of the beam and reducing the vibration conduction between the trolley and the beam, and the hard cross beam was optimized by strengthening the hanging column and the connecting beam and adding diagonal support between the pillar and the portal structure beam. By comparing the values of shear, bending moment, displacement and dynamic stress on the hard span before and after optimization, the amplitude peak after structural optimization is reduced by about 25%, and the application of oblique support and reinforcement of the beam can significantly improve the portal structure vibration.

The accessory to ace Face bow records in clinical practice - Laser Levels assisted Face bow Records

An accurate determination, recording and transfer of jaw relation records from patients to the articulator is essential for appropriate dental restoration function, facial appearance and maintenance of patient’s oral health.1 An unsatisfactory and inaccurate record of maxilla-mandibular relationship will eventually lead to failure of the restoration or prosthesis. Facebow plays an integral part of this maxilla-mandibular relationship transfer from the patient mouth to that of the articulator. The use of facebows is emphasized in prosthodontic textbooks and is widely taught in dental schools, but is still perceived as a complex procedure by most students.2 This article attempts to discuss the utilization of a cross beam laser level as a simple accessory to simplify face bow use and to obtain a repeatable and reliable patient head position while recording jaw relations using face bows. The laser cross beam also serves the purpose of improving the accuracy and speed of making face bow records.

Behaviour and detailing of coupling beams with high-strength materials

High-strength steel (HSS) has the potential to reduce reinforcement congestion and construction difficulties for coupling beams. This paper aims to investigate coupling beams using HSS diagonal bars and HSS transverse reinforcement. Four coupling beam specimens with a clear span-to-depth ratio of 2.0 were built with varying concrete materials and confinement details and tested under quasi-static reversed-cyclic shear loading. Despite using the maximum transverse reinforcement spacing that is allowed in ACI 318–19, all coupling beam specimens exhibited satisfactory seismic performance in terms of adequate deformation capacity and stable hysteretic response. Favorable performance, characterized by a greater damage control ability, larger shear strength, and deformation capacity, was achieved in specimens using high-strength concrete, especially fiber-reinforced high-strength concrete. The coupling beam specimen with confinement provided for the entire beam cross section outperformed the specimen with confinement provided for the individual diagonals. The state-of-practice design methods for coupling beams are evaluated with experimental results.

Surface imaging of breast implants using modern high-frequency ultrasound technology in comparison to high-end sonography with power analyses for B-scan optimization1.

This study aims to evaluate optimized breast implant surface-structure analysis by comparing high-end ultrasound technology with a new high frequency technique. This comparative study used new breast implants with different surfaces in an in vitro setting. Nine idle silicon or polyurethane (PU) breast implants were examined by two investigators in an experimental in vitro study using two high-end ultrasound devices with multi-frequency transducers (6-15 MHz, 9-16 MHz, 12.5-33 MHz).The ultrasound B-Mode was optimized using tissue harmonic imaging (THI), speckle reduction imaging (SRI, level 0-5), cross beam (high, medium, low) and photopic.Using a standardized ultrasound protocol, the implants were examined in the middle (point of highest projection) and lateral, by two independent examiners.Image evaluation was performed on anonymized digital images in the PACS. The aim was to achieve an artifact-free recording of the surface structure, the surface coating, the total image structures and, as far as possible, an artifact-free internal representation of the implants.For independent surface evaluation a score was used (0 = undetectability of surface structures, rich in artifacts, 5 = best possible, artifact free image quality). The quality of ultrasound imaging of breast implant surfaces after the optimization of B-Scan differed significantly comparing high-end ultrasound technology with modern high-frequency ultrasound technology (p < 0,05).The following setting has been found to be the best setting with the highest image quality:B-Mode, SRI value 3, Crossbeam high level with color coded imaging for B- mode. In the total examined frequency range of 6-33 MHz, the highest image quality was found in the average frequency range of 12.5-33 MHz at both measured points. For both devices, device 1 (high-end) and device 2 (high frequency) ultrasound, the image quality was in the12.5-33 MHz frequency range with an average image quality of 3.236. It was significantly higher, than in the lower frequency ranges and the same frequency range with THI. (p < 0,05). The image quality of the high-end sonography device was superior to the conventional high-frequency ultrasound device in all frequency ranges. High-end ultrasound imaging technology was superior in the quality of implant surface evaluation in comparison to high-frequency ultrasound sonography. The gained knowledge can serve as a basis for further multicenter clinical application and studies with the aim to develop an objective, precise tool to evaluate the implant and the surrounding tissue with ultrasound.

One-sided shear retrofit of reinforced concrete beams in existing high-rise buildings

This paper presents the evaluation of one-sided shear retrofit schemes for reinforced concrete (RC) coupling beams in existing buildings. Three full-scale beam Specimens CB1, CB2 and CB3 are planned for cyclic tests. Specimen CB1 represents a RC coupling beam in existing 24-story RC buildings, completed in Taiwan, 2017. Specimens CB2 and CB3 are retrofitted by added stirrups in the increased beam cross section and a bolted a steel plate from only one side of the RC beam, respectively. Test results showed that the shear strengths of the two retrofitted specimens exceeded the force of the RC coupling beam expected at the maximum considered earthquake (MCE) level. Specimen CB1 exhibited flexural-shear failure during the cycle of 5% drift. Specimens CB2 and CB3 exhibited shear failure during the cycle of 4% drift, and then concrete crushing associated with longitudinal bar buckling in the plastic hinge region. The peak shear forces of the added stirrups in Specimen CB2 and of the added steel plate in Specimen CB3 were 34 and 22% of the total shear forces, respectively, at large drifts. The added stirrups in the increased beam cross section provided larger shear force than the bolted steel plate. Both schemes were used to retrofit RC beams in the existing high-rise buildings in New Taipei City.

An electromechanically coupled beam model for dielectric elastomer actuators

In this work, the Cosserat formulation of geometrically exact beam dynamics is extended by adding the electric potential as an additional degree of freedom to account for the electromechanical coupling in the dielectric elastomer actuators. To be able to generate complex beam deformations via dielectric actuator, a linear distribution of electric potential on the beam cross section is proposed. Based on this electric potential, the electric field and the strain-like electrical variable are defined for the beam, where the strain-like electrical variable is work-conjugated to the electric displacement. The electromechanically coupled strain energy for the beam is derived consistently from continuum electromechanics, which leads to the direct application of the material models in the continuum to the beam model. The electromechanically coupled problem in beam dynamics is first spatially semidiscretized by 1D finite elements and then solved via variational time integration. By applying different electrical boundary conditions, different deformations of the beam are obtained in the numerical examples, including contraction, shear, bending and torsion. The damping effect induced by the viscosity as well as the total energy of the beam are evaluated. The deformations of the electromechanically coupled beam model are compared with the results of the 3D finite element model, where a good agreement of the deformations in the beam model and that in the 3D finite element model is observed. However, less degrees of freedom are required to resolve the complex deformations in the beam model.

Use of accelerometers to assess and describe trailer motion and its impact on carcass bruising in market cows transported under North American conditions.

Increased trailer motion, coupled with large accelerations and decelerations, has been associated with decreased carcass quality and increased stress indicators in cattle, sheep, and hogs. However, motion of livestock trailers has not been measured in North-American cattle semi-trailers over long distances (> 1000 km). The objectives of this study were to develop a practical method of measuring transport trailer accelerations, to describe the range of accelerations cattle are exposed to under North American conditions, and to conduct a preliminary analysis of trailer accelerations for each compartment and its effect on carcass bruising. The root mean square (RMS) of acceleration was measured at a sampling rate of 200 Hz in 3 orthogonal axes; x (vertical), y (front-to-rear), and z (lateral; side-to-side) by clamping an accelerometer to the cross beam below each of the five compartments of 8 trailers transporting a total of 330 animals (674 ± 33.3 kg BW) from an assembly yard to a processing facility. Journeys took place on separate days and ranged in duration from 13 to 15.7 h. The number and severity of bruises per carcass were determined prior to trimming for n = 290 carcasses and the number of bruises per carcass ranged between 0.38 and 12.75, whereas the bruising score per carcass ranged between 0.38 and 14.88. Mean number of bruises and severity of bruises (bruising scores were assigned according to size using a three-point scale: 1) ≤ 6.5 cm, 2) 6.5 to 12 cm, and 3) ≥ 12 cm and bruising severity was determined by applying the weighted score to each bruise according to bruise area) per carcass was 4.52 ± 2.43 (n) and 5.31 ± 2.84, respectively. Accelerations in commercial transport vehicles were found to range between 0.33 and 1.90 m/s2, whereas the mean RMS of acceleration for all trailers (n = 31 accelerometers) was 1.01 ± 0.32 m/s2, 0.72 ± 0.31 m/s2, and 0.97 ± 0.30 m/s2 for the x, y, and z axes, respectively. Horizontal acceleration was greatest in the nose, back, and doghouse compartments (P = 0.05), whereas lateral acceleration was greatest in the nose and back compartments (P = 0.08). Although the nose, back, and doghouse compartments had the highest RMS values for the lateral and horizontal axes, there were no significant relationships between bruising and acceleration. Replication of this research is required to further understand the relationships between trailer motion, carcass bruising, and overall animal welfare in cattle transported long distances.

Full-aperture chirped-pulse grating compression with a non-uniform beam

A novel chirped-pulse compression scheme is proposed to pursue higher pulse peak power of chirped-pulse amplifiers based on state-of-the-art gratings. It is characterized by the spectral non-uniformity of the beam cross section as well as by the uniform size of the beam projections on the four compression gratings. The spatial distribution of spectra is well designed so that the beam can remain generally collimated in the compressor and the gratings can be employed with a full work area. The maximum possible output pulse energy can therefore be increased within the damage threshold limit. A detailed design is developed for a scheduled 50-PW optical parametric chirped-pulse amplifier. Results of the numerical simulation on the focused output show that the spot size and pulse duration in the focal plane are close to those of conventional grating compression. Further, it is a promising method for upgrading existing chirped-pulse amplifiers.

Research On Dynamic Stability Of Vibrating Disk Worktable

This paper studies the influence of the material quality in the vibrating plate and the relative height difference of the leaf springs on the stability of the worktable, i n order to obtain the disturbance law; firstly, the control variable method is adopted an d the Ansys workbench software is used to determine the quality of different materials on the worktable under static force. Secondly, the deformation of the beam and the cr ossbeam was compared by a simulation test. The results showed that the heavier the m aterial, the greater the deformation of the upper beam and the smaller the deformation of the crossbeam. Finally, the harmonic response method was used to study the effect of the height difference of the leaf spring on the deformation of the beam and the cro ssbeam of the worktable. The results show that the greater the height difference, the s maller the impact on the stability of the workbench.

Behavior of RC Wide Beams under Eccentric Loading

Wide beams are one of the widely used structural elements in RC buildings due to the many special features that characterize them. The main objective of this research is to investigate the behavior of wide shallow beams under the effect of eccentric loading acting along their cross sections. To achieve that, an experimental program that consisted of seven wide beams was conducted. All beams were loaded using two concentrated loads at their middle third where the main parameters considered were: the magnitude of the load eccentricity, the longitudinal spacing between shear reinforcement, and the arrangement of the longitudinal reinforcement. Following that, a finite element analysis was performed where the analytical model used was first verified using the data from the experimental program. The results from both the experimental and analytical programs were in good agreement. Then, the finite element analysis was extended through a parametric study where other variables were studies such as the compressive strength of concrete, the transverse spacing between stirrups and the longitudinal reinforcement ratio. The results showed that the value of the load eccentricity, spacing between shear reinforcement, the arrangement of the main reinforcement along the beam cross section, and the compressive strength of concrete significantly affected the torsional resistance of shallow wide beams. Conclusions and recommendations are presented which can be useful for future researchers. Doi: 10.28991/cej-2021-03091766 Full Text: PDF