Thin-walled circular tubes have been widely used in space lattice structures and other industrial areas. Steel tubes are prone to corrosion during their service life, significantly reducing their ...loading capacity and threatening the structural safety. This work aimed to investigate the residual moment capacity of corroded circular steel tubes (CSTs) subjected to compression force. The second-order effect of steel tubes was studied based on CSTs with outer diameter D = 100 mm. The effects of corrosion thickness, diameter of corrosion pit, and material strength on the residual moment capacity of CSTs were also investigated. The analytical formula with a second-order polynomial form was proposed for predicting the residual moment capacity of CSTs. The values of tc/t were assumed to be 0.1, 0.3, 0.5, and 0.7, and the values of F/Fu were set to 0, 0.5, and 0.7 to reveal the influence of corroded thickness with different axial compression ratios. The applicability of the proposed formula for CST with yield strength equal to 235, 345, and 460 MPa was also confirmed. According to the findings, the proposed analytical formula can accurately predict the residual moment capacity of CSTs with random pitting corrosion.
•The moment capacity of corroded steel tube is closely related to the Tc and χ.•Moment capacity will be overestimated if pitting corrosion is simplified as uniform corrosion.•The accurate analytical method to predict the moment capacity is proposed.•The proposed method can also be adopted for pitting corrosion with random depth.
The porous lattice structures (PLSs) have the advantages of excellent mechanical properties and light weight. Inspired by the structural shape of lotus root, this work proposes four lotus root-shaped ...bio-inspired PLSs (BPSs), which are triangular BPS (TBPS), quadrangular BPS (QBPS), pentagonal BPS (PBPS) and hexagonal BPS (HBPS). The axial compression properties of these BPSs are investigated. All of these four structures have uniform structural stiffness and excellent energy absorption properties. They exhibit stable deformation modes of X-shape and single-headed axe. In addition, the effects of geometric parameters and cell arrangements on the compression performance of these BPSs are investigated. The BPSs with different geometric parameters show various deformation modes such as single-headed axe, double-headed axe, sun and turtle shapes. The BPSs with different cell arrangements exhibit rich deformation modes such as crescent, dart, X and V shapes. Their cells show the deformation modes of axial crushing and bending, and the axial crushing deformation mode is more conducive to obtaining stable compression performance. Furthermore, the sample of QBPS is manufactured through 3D printing, and the compression experiment is performed to verify the simulation model. These results show that the BPSs are excellent energy-absorbing structures that have wide application prospects.
•Inspired by lotus root, four bio-inspired PLSs are proposed.•These BPSs have excellent EA properties and novel deformation modes.•The BPSs with different cell arrangements exhibit very rich deformation modes.•The compression experiment is performed to verify the simulation model.
The output performance of the current origami inspired Triboelectric Nanogenerator (TENGs) are limited by the simple origami pattern used as the TENGs base. Here, we propose a kind of origami ...tessellation (OT) base to enhance the electric output performance of TENG and facilitate its application in road pavement for energy harvesting. The OT base provides multi layers facets to install tribo-pairs and can be driven by very small stimulation owing to the resilience of the structure. It can be operated effectively under either traction or compression depending on the initial configuration of the OT base. Besides, the foldability of the OT base makes easily the developed devices to be fitted thin gap in the road pavement. A series of mechanical tests are carried out to study the output performance of a quadrangular prism shape OT-TENG based on the Arc pattern under different boundary conditions and frequencies. To guarantee the motion synchronicity of the OT base, a strip-shape OT-TENG based on the Miura pattern is designed to obviously increase the output performance as the number of the tribo-pairs increases. Then, the tracking board test shows the potential application of the OT-TENGs for pavement vibration energy harvesting. By constructing a two-dimensional network of the OT-TENGs in pavement, the devices will provide a feasible green energy to meet the energy need of the intelligent transportation systems in the future. The outcomes of this work offer a novel OT-TENG design with great potential to dramatically enhance the output performance of TENGs devices in more general shape space and more flexible environment for vibration energy harvesting.
A sketch of the developed Miura pattern OT-TENGs in application of pavement vibration energy harvesting: (a) Perspective of the device arrangement in the pavement; (b) Illustration of the energy harvesting unit; (c) Illustration of the OT-TENG device; (d) Illustration of the Miura pattern OT base; (e) Illustration of the tribo-pair installed in the OT base. Display omitted
•Origami tessellation (OT) based TENGs are proposed to greatly enhance the electric output.•OT bases provide multi shapes and multi layers facets to install tribo-pairs.•OT-TENGS can be operated effectively under either traction or compression.•OT-TENGS have great potential application for pavement vibration energy harvesting.
Background: The objective of this study was to determine interfragmentary compression forces based on screw length and geometry for simulated proximal scaphoid fractures. Methods: Sixty-four foam ...model simulated fractures were stabilized with screws of various length (10 mm, 18 mm, 20 mm, or 24 mm) and geometry (central threadless or fully threaded) across a proximal fracture. Interfragmentary compression was measured at the simulated fracture site upon fixation. An independent sample t test and 1-way analysis of variance were performed to assess differences in interfragmentary compression. Results: Fixation utilizing a 10-mm screw generated significantly less interfragmentary compression than fixation utilizing a 20-mm or 24-mm screw. When accounting for both screw length and geometry, an 18-mm central threadless screw generated greater interfragmentary compression than a 20-mm and 24-mm fully threaded screw; there was no significant difference in compression between an 18-mm and 24-mm central threadless screw. Conclusions: The design of headless compression screws allows for maximal interfragmentary compression at the screw midpoint; we questioned whether a short screw centered on the fracture site resulted in superior compression to a longer, noncentered screw. Our data suggest that centering a small screw (10 mm) along a proximal fracture generates significantly less interfragmentary compression than a longer, noncentered screw. Our results demonstrate that balance between maximizing screw length and centering the screw on the fracture is vital toward maximizing interfragmentary compression for the fixation of proximal third scaphoid fractures.
This study aimed todetermine the effect of physiotherapists’ physical burden caused by different bedheights during manual therapy. Thirty-three male physiotherapists performedtasks simulating lumbar ...massage and passive hip abduction range-of-motionexercise (ROM) on the beds with low height (LH) and adjusted height (AH), witheach task performed three times. The anterior inclination angle of thephysiotherapist’s trunk was measured, the surface electromyograms of theerector spinae and trapezius muscles were recorded, and perceived stress wasassessed. The indexes obtained were statistically compared for different bedheights. Additionally, the lumbar disc compression force and flexion torquewere estimated. The lumbar burden caused by the excessive bending and thebiomechanical burden and perceived stress were stronger at LH than AH. In ROM tasks using the right hand, the muscleactivity was lower at the left lumbar region at LH than at AH. At LH, the anteriorinclination angle increased and the lumbar muscle activity declined as the numberof tasks increased. The burden on the shoulders was not significantly differentby bed heights. Our results showed that, when physiotherapists perform manualtherapy, it is necessary to adjust the bed height to reduce physicalburden and ensure higher quality of service.
•Particles invade the sealing interface are difficult to avoid downhole.•Particles invasion has been investigated from theory and tests.•Displacement Model in particles invasion was discussed and ...validated.•Particles sizes and compression rates affected particles invasion.•Particles sizes control at the sealing interface was attempted.
Particles invasion into sealing interface is difficult to avoid in downhole conditions, which directly induces the failure of FKM O-ring dynamic seals. To enhance the performance of hard/soft dynamic seals in particles environment, the work on particles invasion has been initiated. A displacement model for particles invasion was developed and tested. In-situ observations were used to investigate particles invasion process under different particles sizes and assembly compression forces. Theory and tests showed matching results that particles sizes and compression forces had significant effects on particles invasion. In addition, a particles sizes control strategy based on the model was tested. This work has clarified the invasion behavior of particles and provided recommendations for the elastomer dynamic seals assembly in particles environment.
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In in-process quality monitoring for Continuous Manufacturing (CM) and Critical Quality Attributes (CQA) assessment for Real-time Release (RTR) testing, ultrasonic characterization is ...a critical technology for its direct, non-invasive, rapid, and cost-effective nature. In quality evaluation with ultrasound, relating a pharmaceutical tablet’s ultrasonic response to its defect state and quality parameters is essential. However, ultrasonic CQA characterization requires a robust mathematical model, which cannot be obtained with traditional first principles-based modeling approaches. Machine Learning (ML) using experimental data is emerging as a critical analytical tool for overcoming such modeling challenges. In this work, a novel Deep Neural Network-based ML-driven Non-Destructive Evaluation (ML-NDE) modeling framework is developed, and its effectiveness for extracting and predicting three CQAs, namely defect states, compression force levels, and amounts of disintegrant, is demonstrated. Using a robotic tablet handling experimental rig, each attribute’s distinct waveform dataset was acquired and utilized for training, validating, and testing the respective ML models. This study details an advanced algorithmic quality assessment framework for pharmaceutical CM in which automated RTR testing is expected to be critical in developing cost-effective in-process real-time monitoring systems. The presented ML-NDE approach has demonstrated its effectiveness through evaluations with separate (unused) test datasets.
The compression behavior of hydrophilic chitosan has been investigated as a function of molecular weight (MW), ranging from 8 to 100kDa. Powder packing, plasticity, elasticity, brittle-fracture ...nature were evaluated using force displacement curves and Heckel/Kawakita analysis upon compression of different MW chitosan powders. The compacts produced were subjected to ejection work determination and tensile strengths analysis, the later using Leuenberger equation. Molecular modeling was used to correlate the MW-binding energy dependence on the physical strength of the chitosan compacts. The high work of compression of the low MW (≤30kDa) chitosans is accounted for their brittle nature upon compression. At high compression forces (>3kN), the low MW chitosan compacts exhibited slightly lower tensile strength due to their increasing extents of elastic recovery and ejection work. Lower particle size of chitosan enhances lower fragmentation, packing, and frictional tendency that can be related to an increase in plastic deformation and compacts tensile strength. In molecular modeling, the calculated higher binding energies of the high MW chitosan (88kDa) than that of the low MW chitosan (8kDa) may further explain its rigid, complex nature when compared to low MW chitosan. Upon compression, increasing MW of chitosan is manifested as higher energies for densification which in turn determines the extent of helical packing from intermingled molecular to open structure as the MW is decreased. Such changes in structural configuration are suggested to contribute to the transfer from plastic to brittle-fracture nature with high packing extent of chitosan upon compression when the MW is reduced. The foregoing may justify the slow diclofenac Na drug release upon dissolution testing when low MW chitosan is used in tablet preparation.
Chemical structure of d-glucosamine (A), high MW (B) and low MW (C) chitosans. Display omitted
•Tensile strength of chitosan compacts is associated with chitosan molecular weight.•Low chitosan compacts tensile strength is attributed to high elastic recovery.•High MW chitosan has a more stable structure than the low MW chitosan.•High MW chitosan provides immediate release properties in solid form preparations.•Low MW chitosan provides sustained release properties
•Mammography is an essential examination in the early discovering of breast cancer.•Active involvement of the patient in the procedure can improve the imaging protocol outcome.•Self-compression ...significantly influenced the increase of compression force by 21.7 %.•The increase of compression force leads to a decrease of breast thickness by 5%.•Both stated facts lead to a decrease of mean glandular dose by 6.3 %.
The purpose of the study was to investigate whether the use of self-compression in craniocaudal (CC) projection has an effect on compression force, breast thickness, radiation dose and image quality compared to the standard mammographic procedure.
The study was conducted on 200 female patients that were referred for mammographic imaging. Patients were randomly divided into two equal groups. In the first group, self-compression was performed on the right breast and in the second group on the left breast. The data about compression force (N), breast thickness (mm), and mean glandular dose (MGD; mGy) were collected. In addition, the differences in the mentioned variables according to the side of self-compression were compared. All mammographic images were evaluated by two experienced radiologists according to the criteria established by the European Commission.
The use of self-compression resulted in a significant increase in compression force by 21.7 % (19.8 N) and a significant reduction of breast thickness by 5% (2.43 mm) and MGD by 6.3 % (0.09 mGy), respectively. There were no statistically significant differences based on the self-compression side, and no differences were observed in image quality assessment.
This study demonstrates that the imaging protocol in mammography of the CC projection can be adopted by the use of self-compression in order to achieve better results.
The formation mechanism between {101‾2} twins (TWs) and prismatic slip (PR) in the Zircaloy-4 alloy was investigated by the situ study of Transmission Kikuchi Diffraction (TKD) as well as ...transmission electron microscope (TEM) methods. Our results reveal that the PR and TWs were easily formed on the (101‾0) plane, due to the high Schmid factor values of PR (0.46) and TWs (0.5) were caused by the compression force (CF) – F(30, 90). Moreover, the relationship between CF and driving force (DF) of PR was got as DF = CFcos30°.
•The formation mechanism between PR and TWs on (101‾0) plane was studied.•The PR and {101‾2} twins (TWs) were situ observed in TEM and TKD, respectively.•The relationship between CF and driving force (DF) of PR was got as DF = CFcos30°.•The Schmid theory and experiment was verified by each other in the first time.
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