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Piezoresponse Force Microscopy (PFM) is capable of detecting strains in piezoelectric materials down to the picometer range. Driven by diverse application areas, numerous weaker electromechanical materials have emerged. The smaller signals associated with them have uncovered ubiquitous crosstalk challenges that limit the accuracy of measurements and that can even mask them entirely. Previously, using an interferometric displacement sensor (IDS), we demonstrated the existence of a special spot position immediately above the tip of the cantilever, where the signal due to body-electrostatic (BES) forces is nullified. Placing the IDS detection spot at this location allows sensitive and BES artifact-free electromechanical measurements. We denote this position as x I D S / L = 1 , where x I D S is the spot position along the cantilever and L is the distance between the base and tip. Recently, a similar approach has been proposed for BES nullification for the more commonly used optical beam deflection (OBD) technique, with a different null position at x O B D / L ≈ 0.6 . In the present study, a large number of automated, sub-resonance spot position dependent measurements were conducted on periodically poled lithium niobate. In this work, both IDS and OBD responses were measured simultaneously, allowing direct comparisons of the two approaches. In these extensive measurements, for the IDS, we routinely observed x I D S / L ≈ 1 . In contrast, the OBD null position ranged over a significant fraction of the cantilever length. Worryingly, the magnitudes of the amplitudes measured at the respective null positions were typically different, often by as much as 100%. Theoretically, we explain these results by invoking the presence of both BES and in-plane forces electromechanical forces acting on the tip using an Euler–Bernoulli cantilever beam model. Notably, the IDS measurements support the electromechanical response of lithium niobate predicted with a rigorous electro-elastic model of a sharp PFM tip in the strong indentation contact limit [ d e f f ≈ 12 pm / V , Kalinin et al., Phys. Rev. B 70, 184101 (2004)]. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW)-layered materials, such as graphite, exhibit unique mechanical properties owing to their structural and mechanical anisotropies. This study reports the development of a mechanical model that reproduces the characteristics of the nonlinear and reversible bending deformation of vdW-layered materials, while taking into account the microscopic mechanism of the discrete interlayer slips. The vdW-layered material was modeled as a stack of interacting discrete deformable layers (semi-discrete layer model), and the interlayer interaction was modeled using a cohesive zone model that reproduced the localized interlayer slip. Using the finite-element method, out-of-plane bending deformation analyses were performed on the cantilevers of the highly oriented pyrolytic graphite (HOPG) and MoTe2, and the validity of the model was verified by comparing it with the experimental results. The model accurately reproduced the loading and unloading behaviors in the experiments for the submicron HOPG cantilevers or the large nonlinear and reversible deformation with a hysteresis loop. Furthermore, the model reproduced well the characteristics of the bending experiments for the micro-MoTe2 cantilevers, or the intermittent decrease in stiffness during the loading process and deformation restoration during the unloading process. These results demonstrated that the designed semi-discrete layer model can be universally applied to reproduce the bending deformation characteristics of a variety of vdW-layered materials and can be employed to effectively elucidate the underlying deformation mechanisms. [ABSTRACT FROM AUTHOR]

Bridges are vital assets of transport infrastructure, systems, and communities. Damage characterization is critical in ensuring safety and planning adaptation measures. Nondestructive methods offer an efficient means towards assessing the condition of bridges, without causing harm or disruption to transport services, and these can deploy measurable evidence of bridge deterioration, e.g., deflections due to tendon loss. This paper presents an enhanced input-doubling technique and the Artificial Neural Network (ANN)-based cascade ensemble method for bridge damage state identification and is exclusively relying on small datasets, that are common in structural assessments. A new data augmentation scheme rooted in the principles of linearizing response surfaces is introduced, which significantly boosts the efficiency of intelligent data analysis when faced with limited volumes of data. Furthermore, improvements to a two-step ANN-based ensemble method, designed for solving the stated task, are presented. By adding the improved input-doubling methods as simple predictors in the first part of the cascade ensemble and optimizing it, we significantly boost accuracy (7%, 0.5%, and 8% based on R2 in predicting tendon losses for three critical zones that were defined across the deck of a real deteriorated prestressed balanced cantilever bridge). This improvement is strong evidence of the accuracy of the proposed method for the task at hand that is proven to be more accurate than other methods available in the international literature. [ABSTRACT FROM AUTHOR]

Context: Airborne pathogens, defined as microscopic organisms, pose significant health risks and can potentially cause a variety of diseases. Given their ability to spread through diverse transmission routes from infected hosts, there is a critical need for accurate monitoring of these pathogens. This study aims to develop a sensor by investigating the vibrational responses of cantilever and bridged boundary-conditioned single-layer graphene (SLG) sheets with microorganisms, specifically SARS-CoV-2, attached at various positions on the sheet. The dynamic analysis of SLG with different boundary conditions and lengths was conducted using the atomistic finite element method (AFEM). Simulations were performed to evaluate SLG's performance as a sensor for biological entities. Altering the sheet's length and the mass of the attached biological object revealed observable frequency differences. This sensor design shows promise for enhancing the detection capabilities of graphene-based technologies for viruses. Methods: Finite element method (FEM) analysis is employed to model the sensor's performance and optimize its design parameters. The simulation results highlight the sensor's potential for achieving high sensitivity and rapid detection of SARS-CoV-2. Bridged and cantilever boundary conditions are applied at the ends of the SLG structure by using ANSYS software. Simulations have been conducted to observe how SLG behaves when used as sensors. In armchair graphene, under both boundary conditions, an SLG (5, 5) structure with a length of 50 nm displayed the highest frequency when a SARS-CoV-2 molecule with a mass of 2.6594 × 10−18 g was attached. Conversely, the chiral SLG (17, 1) structure exhibited its lowest frequency at a length of 10 nm. This insight is crucial for grasping detection limits and how factors such as size and boundary conditions influence sensor efficacy. These biosensors hold immense promise in biological sciences and medical applications, revolutionizing patient care by enabling early detection and accurate pathogen identification in clinical settings. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The continuous improvement of bridge construction technology has resulted in an ongoing expansion of bridge spans, which has concomitantly increased the difficulty of controlling the alignment of long-span bridges during construction. In order to address the issue of the grey prediction model exhibiting a significant discrepancy in its alignment predictions for long-span continuous girder bridges, a pre-camber prediction method for bridges based on a combination of the grey model (GM) and BP neural network (GM-BP) is proposed. Firstly, the parameters are identified according to their influence on the pre-camber, and the appropriate parameters are selected as the original data to improve the efficiency of prediction. Subsequently, the original data are preliminarily fitted by the GM(1,1) model, and the predicted values are used as inputs for training the neural network. Finally, the new predicted values are output using the nonlinear fitting ability of the BP neural network. To assess the efficacy of the model, it is applied to the prediction of the pre-camber of the girder segments of a bridge under cantilever construction. The pre-camber prediction for 11#–13# girder sections was based on 10 sets of monitoring data from constructed girder sections. The results demonstrated that the average relative error of the GM-BP combined prediction model was 3.01%, which was 5.68% less than that of the GM(1,1) model, and the overall prediction exhibited a closer alignment with the original data. The GM-BP combined prediction model is an effective method for ensuring the alignment control of bridge construction and is able to achieve high accuracy and stability in its predictions in the case of limited and irregular data. [ABSTRACT FROM AUTHOR]

The timber lounge bridge with cantilever beams is a kind of bridge architectural heritage that is different from the simply supported timber beam bridge and timber arch lounge bridge in typology. It has important historical, artistic, and scientific values. For the preventive protection and repair of the timber lounge bridge with cantilever beams, this paper proposes a scientific and reliable quantitative evaluation method for its structural safety status, taking the typical timber lounge bridge with cantilever beams, Yongqing Bridge, as a case study. The evaluation consists of three stages: firstly, analyzing the typology of the timber lounge bridge with cantilever beams and recording the deterioration; secondly, establishing the evaluation system and grading criteria for the timber lounge bridge with cantilever beams; thirdly, using the finite element method to calculate the importance of the components and quantitative evaluating the structural safety status of the timber lounge bridge with cantilever beams by using the improved analytic hierarchical process (IAHP) and making the final decision. The results of this study can provide a scientific basis for quantitative evaluation of the structural safety status, preventive protection, and repair of the timber lounge bridge with cantilever beams. [ABSTRACT FROM AUTHOR]

Some arms of nanorobots display L-shaped structures. The transverse free bending vibration of an L-shaped cantilever nanobeam carrying a tip nanoparticle is investigated. Based on the nonlocal elasticity, the nonlocal parameter is introduced to capture the size effect of the mechanical behavior of the cantilever–mass system. The frequency equation is deduced analytically. Exact resonance frequencies of the L-shaped nanocantilever–mass system are numerically evaluated and compared with their corresponding values of the macro-scale L-shaped cantilever–mass system. The numerical results show that the nonlocal parameter declines the resonance frequencies. If removing the nonlocal parameter, our results reduce to the resonance frequencies of transverse bending vibration of L-shaped cantilevers with an attached tip mass. The effects of the nonlocal parameter, the ratio of the attached mass to the structure mass, the length ratio of two members of the L-shaped cantilever–mass system on the resonance frequencies are analyzed. [ABSTRACT FROM AUTHOR]

This paper highlights the development and validation of two innovative modular cantilever (MC) designs for railway overhead applications. Existing MCs are heavy, complex, and prone to failures. Addressing these shortcomings, the proposed designs leverage topology optimization and TRIZ principles to achieve significant improvements: weight reduction: Up to 28% lighter than existing MCs due to optimized material distribution. Enhanced robustness: Improved structural efficiency and strength, reducing failure risk. Simplified assembly and maintenance: fewer components and modular design facilitate easier handling and installation. Environmental resistance: increased durability against fatigue cracking, corrosion, and wear and tear. Numerical calculations and finite element analysis validate the performance of the new designs, confirming their ability to withstand dynamic loading conditions equivalent to traditional MCs. These lightweight, robust, and adaptable solutions offer tremendous potential for reducing costs, improving safety, and optimizing performance in railway overhead applications. [ABSTRACT FROM AUTHOR]

Copyright of Roads & Bridges / Drogi i Mosty is the property of Road & Bridge Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A satellite with two solar wings can be modeled using a pair of symmetric flexible cantilever beams connected to a central rigid body. Due to certain reasons, the symmetric flexible cantilever beams may be turned into asymmetric ones, which will inevitably influence the vibration properties of the structural system. By changing the structural sizes and adding local mass on one side of the two beams, a structural system with asymmetric mass distribution is obtained and its vibration characteristics are investigated. Hamilton's principle with the assumed mode method is employed to establish the equation of motion of the asymmetric structural system. The natural frequencies, mode shapes, frequency response curves and displacement time histories of the system are calculated, and they are compared with those of the structural system with a symmetric mass distribution. The correctness and feasibility of the present analytical method are verified by means of the finite element method (FEM) and a vibration experiment. The analytical results show that the mass asymmetry of the two beams leads to the mode localization phenomenon, and the coupling effect between the two beams and the central rigid body is enhanced. The larger the mass asymmetry is and the closer the position of the added local mass to the end of the cantilever beam is, the more obvious of the mode localization phenomenon is and the more obvious of the coupling effect between the two beams and the central rigid body is. The present investigation results are helpful for the dynamic analysis and design of spacecraft structures composed of flexible solar wings and a central rigid body. [ABSTRACT FROM AUTHOR]

Achieving full equilibrium for the horizontal component force of the backstay in cable-stayed arch bridges is challenging, and the stiffness of the buckle tower has a notable influence on the overall shape of the main arch structure. Increased stiffness in the buckle tower leads to reduced construction complexity. Therefore, this study proposed a method of enhancing the longitudinal thrust stiffness of the buckle tower using the joint effect of approach bridges. A sensitivity analysis was conducted on the approach bridge-composite buckle tower structure to determine the optimal combination method, resulting in the formulation of an analytical expression for the thrust stiffness of this structure. In this study, numerical analysis was performed to explore the composition mechanism of the thrust stiffness influenced by the pier-girder connection, and we discussed the applicability of the joint effect of approach bridges during the cantilever assembly process of arch ribs. The following conclusions were obtained: 1) prior to installing the main girder of the approach bridge, when the steel buckle tower and the junction pier have already been secured, the most effective approach is to form a "T" rigid structure by firmly connecting the main girder of the approach bridge with the composite buckle tower. This configuration provides self-weight deflection and pier-girder rotation restriction effects. 2) The study presents analytical formulas for the completely rigid pier-girder connection of the approach bridge-composite buckle tower structure, partially rigid pier-girder connection, and pre-deviation. Combined with the calculation program, this can guide structural design. 3) When a large downward elevation error of the arch ribs occurs in the middle and later stages, the cable force needed to install new arch segments becomes overly large. Therefore, the joint effect of approach bridges can be utilized to substitute for a portion of the cable force, effectively reducing potential elevation errors that might arise in subsequent arch ribs in the absence of this joint effect. [ABSTRACT FROM AUTHOR]

This study aimed first to compare the shear bond strength between zirconia samples luted to enamel with a 10-MDP- containing resin cement (Panavia F2.0, Kuraray, Japan) and those luted with a resin cement using a separated 10-MDP monomer-containing bottle (Panavia V5, Kuraray, Japan). The second objective was to evaluate the bond stability after 150 days of aging in water, between enamel and zirconia ceramic surface enhanced with a glass-ceramic coating. 80 specimens composed of ceramic cylinders and enamel disks were obtained, within eight experimental groups (n = 10). 60 zirconia cylinders (Katana STML zirconia, Kuraray, Japan) were assigned to 3 groups according to their surface treatment: milled/sintered surface (ZRCT), tribochemical silica-coating (Cojet™ Sand, 3 M ESPE, Seefeld, Germany) (ZRTC), and glass-ceramic coating (IPS e.max Zirpress) (ZRZP). 20 cylinders of lithium disilicate had a milled surface (IPS e.max CAD, Ivoclar-Vivadent, Schaan, Liechtenstein) (ECAD). The cylinders of each group were further divided into two subgroups according to the resin cement used: Panavia F2.0 (-PF) and Panavia V5 (-PV). All specimens were stored in distilled water for 150 days before shear bond strength (SBS) tests. The fracture mode was analyzed, and data were statistically computed (two-way ANOVA, post hoc Tukey test, p < 0.05, SPSS, IBM, v26). The ECAD-PF group recorded the highest SBS values (31.75 ± 2.2), and the ZRCT-PF group recorded the lowest values (5.59 ± 1.1). The two-way ANOVA test showed that ceramic surface treatment had a statistically significant effect on SBS (F (3,72) = 38.95, p < 0.001) while the type of ARC did not (F (1,72) = 2.40, p = 0.126). Tukey's post hoc test revealed no statistical difference between the ZRZP and the ZRTC or ECAD groups. Within the limitations of this study, the PV resin achieved similar shear bond strength results between tribocoated zirconia and enamel compared to the one for glass-ceramic and enamel. Furthermore, a long-term durable bond, similar to the glass-ceramic one, was achieved with the heat pressed ceramic coated specimens. Thus, this new surface treatment could be recommended for anterior cantilever bridges for its fracture resistance and bonding ability. [ABSTRACT FROM AUTHOR]

Propped cantilever truss is not a common bridge construction technique. The performance of such bridges under operational and extreme loading is not reported in the literature either. In this paper, failure mechanisms in a propped cantilever truss bridge are reported using field investigation. The field observations are supplemented by numerical analysis to identify the causes of failure. A a systematic account of damage mechanisms in bridge components is also reported. The failure of the Lamgadi Bridge over the Seti River in Nepal is used as a case study example. The loading and construction protocols are detailed, and numerical analysis results are juxtaposed with the field observations to explain the failure mechanisms. Field observations and numerical results show that lack in adequate design is the most likely cause of the bridge collapse. Numerical results also indicate that the roller support at the propped end, unlike the hinged pot bearing used in the as constructed bridge would have been a safer choice. The failure could have been easily prevented with proper numerical simulation of the bridge response during the design phase. [ABSTRACT FROM AUTHOR]

An approximate method for sizing continuity tendons in cast-in-place segmental cantilever box girders is presented in this technical note. Variables investigated are the length of the main span, the length of the continuity tendons, and the geometry of the box girder. Results indicate that secondary moments due to the prestressing of the continuity tendons decrease as the span length increases and as the length of continuity tendon decreases. For girders with a curved soffit, it was found that the type of variation of the girder depth (e.g., parabolic, cubic) has a small effect on the magnitude of the secondary moments. [ABSTRACT FROM AUTHOR]

This paper describes a study of deformation of an ideal elastoplastic adhesive layer of a sample in the form of an elastic double-cantilever beam. The integral values are determined for a number of adhesives with account for all diagonal stress tensor components in the layer. It is shown that the integral value is significantly affected by the plane problem type in the case where an elastic-plastic model of layer deformation is applied. As demonstrated in the study, compressive stresses may be present during normal fracture in the irreversible deformation region of the adhesive in a plane stressed state. [ABSTRACT FROM AUTHOR]

In the paper, the numerical solution to the linearized problem of a partially clamped, partially free rectangular plate is considered in order to model and simulate the unstable end behavior. Such a problem is modeled by a nonlinear plate evolution equation with stretching effects in the span-wise direction and wind-flow in the chord-wise direction. The motivation is to model a cantilever bridge in order to consider the long-time behavior of a nonlinear elastic structure forced by external/internal inputs. The non-conservative force acting upon the system and the resulting loss of dissipativity of the system are the major features. The dependence of the structure of stationary states on the values of the gas velocity will be analyzed. A numerical approximation with a Morley finite element is adapted to the plate with clamped-free edges, and corresponding numerical computations are provided. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to develop a comprehensive dynamic modeling and analysis method based on the absolute node coordinate method to predict the impact of the member flexibility on the dynamic performance of scissor deployable structure under the framework of flexible multi-body dynamics. In the process, three locking problems in the classical plane shear beam element are reviewed and discussed. Then a novel non-locking planar beam element is proposed to solve the element locking problem, and the dynamic model of the scissor deployable structure is established. Next, the cantilever beam, simply supported beam and flexible simple pendulum are respectively used to verify the correctness of the proposed non-locking beam element from the static and dynamic perspectives. Finally, the simulation and experiment results show that the proposed new non-locking element and normal matrix modeling method can effectively evaluate the dynamic performance of deployable structure and improve the computational efficiency. This study not only provides theoretical guidance for the dynamic behavior analysis and prediction of scissor deployable structure, but also offers reference for the layout and design of same type mechanisms. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper's main aim was to explain the process of characterising the structural over-strength factor (R), seismic behaviour factor (Q), and the effective elastic stiffness, Keff, of cantilever-reinforced concrete (RC) urban bridge columns with solid circular cross-sections for use in seismic design under the Serviceability Limit State (SLS). Similarly, mathematical models have been proposed to determine the average values of effective stiffness and seismic response modification factors suggested for cantilever-reinforced concrete bridge columns at SLS. This is because multiple design codes stipulate that cantilever RC bridge columns must meet the SLS requirements. Therefore, to comply, the lateral displacement ductility demand must not exceed unity after a moderate or small earthquake. While the behaviour of the materials remains in the elastic range, this performance criterion can be conservative. If the materials undergo small deformations, the slight damage can be quickly repaired to meet the SLS. [ABSTRACT FROM AUTHOR]

The paper presents the Structural Health Monitoring system installed on the posttensioned concrete road bridge over the Odra River in Poland. The bridge superstructure has a form of the 5‐span box girder with skewed supports, built using the cantilever method. During operation of the bridge (since 2010) many cracks arrived in the superstructure, mainly within the main bridge span with a length of 140 m. Therefore, as a part of a complex diagnostic process, the monitoring system were incorporated for assessment of the bridge performance and for observing further propagation of damage. The implemented monitoring system utilizes Fiber Bragg Grating (FBG) technique for measuring of strains, changes of cracks width and angular displacements of concrete box girder for various operating conditions of the structure including effects of regular road traffic, environmental influences and rheological phenomena. The paper presents applied testing and measuring procedures as well as results of the monitoring. Conclusions regarding effectiveness of the applied testing method in identification of the bridge condition are formulated and discussed. [ABSTRACT FROM AUTHOR]

Box girders with steel cantilevers underneath the deck are frequently used in the design of composite steel bridges. Hereby, the welded joints between the main girder and the transverse system have to endure fatigue loads. Current design specifications for this joint, e.g., a tapering in thickness of the top flanges at the same position of a transition radius, are complex to manufacture and provide a higher fatigue resistance than necessary. This article addresses the optimization of this structural detail, which is realized hundreds of times per structure. Several laboratory tests and numerical simulations were carried out regarding the load‐bearing behavior and the fatigue safety of the cantilevers as double‐T‐sections and as box girders. Additionally, 60 fatigue tests were conducted on small‐scale specimen to classify the resulting simplified design variants in detail categories of the nominal stress concept. As a result, two design recommendations are proposed for the joint at the intersecting top flanges. Moreover, the effect of an unplanned axial misalignment on the fatigue strength of the joint at the bottom flange is quantified. [ABSTRACT FROM AUTHOR]

To investigate the automatic monitoring technology of key construction nodes and structures of super-large bridges constructed with cantilever, the 0# block radar measurement and control, the settlement monitoring of construction sections and the mechanical response monitoring of whole bridge were carried out during the deformation and stress stages of the cantilever construction bridge section. The measurement and control data of stress and deformation in actual construction and simulation data were compared and analyzed, and the safety state of bridge section during construction was judged by the coincidence. By the mathematical statistics method, the accuracy of radar monitoring data was compared with that of traditional monitoring data. The research results show that radar monitoring can work around the clock and can analyze typical fluctuations in cloud images in combination with construction logs. The fitting value of millimeter-wave radar monitoring block 0# deformation data is 0.051 44, which is better than 0.006 32 of the traditional monitoring method and has stronger correlation with the numerical simulation curve. During the whole construction period, the monitoring data of the force and deformation of each segment of the whole bridge fluctuate around the theoretical values with small fluctuation range, and the continuous beam is always in safe state. [ABSTRACT FROM AUTHOR]

Based on the bending deformation theory of cantilever beam, the mathematical model of bending deformation of single valve slice under uniform load is proposed and deduced by using the microbeam element method (MEM). The accuracy and reliability of the mathematical model established by the MEM and the small deflection method (SDM) are verified through the finite element simulation comparison. The results show that the valve slice deformation mathematical model under uniform load established by using the deformation theory of the MEM is suitable not only for the small deflection deformation (SDD) but also for the large deflection deformation (LDD) of the valve slice, and can reflect the dynamic deformation characteristics of the valve slice more truly than the SDM, which provides a certain theoretical basis for the deformation study of single valve slice. At the same time, the mathematical model is used to simulate the deformation law of the valve slice when the thickness, inner radius and outer radius change. The conclusion provides technical support for the design and performance prediction of the shock absorber. [ABSTRACT FROM AUTHOR]

This article discusses the construction of a nodal bridge on Shanghai Rail Transit Line 10 above Line 6. Based on the analysis of the advantages and disadvantages of various construction methods, a new type of asymmetric loading cantilever assembly method with a bridge erecting machine is proposed. Firstly, the east half of the bridge is constructed to form a T-shaped structure, and then the bridge erecting machine uses the built T-shaped structure to provide a fulcrum to pass the holes and complete the construction of the west half of the bridge. The two parts are then closed. The method proposed in this paper can solve construction issues when working space under a bridge is limited, and the conventional balanced cantilever assembly method cannot be used for construction. [ABSTRACT FROM AUTHOR]

Introduction. Management of missing maxillary lateral incisors can be a challenging endeavour for dentists. Whether from agenesis or tooth loss, several treatment modalities are currently present to tackle this task to ensure satisfactory aesthetics. Most patients, especially younger patients are more likely to prefer fixed prosthodontic rehabilitation. Among these options is the computer-aided design and computer-aided manufacturing polymethyl methacrylate (CAD/CAM PMMA) cantilever bridge. Case Descriptions. These two clinical cases describe the management of missing lateral maxillary incisors in two Tunisian female patients with different etiologies, using CAD/CAM PMMA cantilever bridge. Conclusions. CAD/CAM technologies allow for a fairly quick and simple try-in thanks to their high accuracy as well as being predictable, minimally invasive, and affordable treatment options. This type of restoration can be put to use for mid- to long-term solutions to missing maxillary lateral incisors. However, its success depends mainly on patient selection regarding age, general health, occlusal context, and proper indication. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: All-ceramic cantilever bonded bridge has become a hot topic in the clinical aesthetic restoration of anterior teeth due to its advantages in treatment time, invasiveness, aesthetics and price. OBJECTIVE: To summarize the solutions to the clinical technical difficulties of all-porcelain cantilever bonded bridge and its advantages in the application of anterior teeth, and to introduce the clinical follow-up methods of the existing all-porcelain cantilever bonded bridge, in order to provide clinical and scientific guidance in the field of aesthetic repair of partial dentition defects of anterior teeth. METHODS: The articles published from 1955 to 2021 were retrieved by the first author on Web of Science, PubMed, CNKI, and Wanfang databases. The English search terms were “denture, partial, fixed, resin-bonded, resin bonded bridge, Maryland bridge, adhesive bridge, single-retainer, all-ceramic”. The Chinese search terms were “bonded bridge, Maryland bridge, adhesive bridge, all-ceramic, cantilever, single-retainer”. Totally 60 articles were summarized for review after screening. RESULTS AND CONCLUSION: (1) Effective surface pretreatment with zirconia ceramic material could prevent the occurrence of fracture. Designing the retention form of the box-shaped hole near the gap side and the nail hole at the bulge of the tongue is one of the current consensus of experts, which can effectively reduce the occurrence of bonded bridge shedding and improve the long-term retention effect. Under the condition of meeting the indications, the all-ceramic cantilever adhesive bridge has the advantages of low incidence of complications such as caries and periodontal disease, good aesthetic effect, and long retention time, and can be used as a permanent restoration. (2) For clinical studies, in addition to counting the basic success rate of retention rate, it is recommended to simultaneously use the oral health-related quality of life questionnaire, satisfaction questionnaire, and the American Public Health Association prosthesis evaluation criteria to comprehensively evaluate the repair effect. (3) It should be noted that different studies have defined the retention rate and success rate differently, which makes certain deviation for data statistics. Therefore, the actual clinical effect of all-ceramic cantilever bonded bridge is worthy of further investigation. [ABSTRACT FROM AUTHOR]

Knowing the extent of displacement experienced by railroad bridges when loaded is useful when evaluating the safety and serviceability of the bridge. However, measuring displacements under train crossing events is difficult. If simplified reference-free methods would be accurate and validated, owners would conduct objective performance assessment of their bridge inventories under trains. Researchers have developed new sensing technologies (reference-free) to overcome the limitations of reference point-based displacement sensors. Reference-free methods use accelerometers to estimate displacements, by decomposing the total displacement in two parts: a high-frequency dynamic displacement component, and a low-frequency pseudostatic displacement component. In the past, researchers have used the Euler-Bernoulli beam theory formula to estimate the pseudostatic displacement assuming railroad bridge piles and columns can be simplified as cantilever beams. However, according to railroad bridge managers, railroad bridges have a different degree of fixity for each pile of each bent. Displacements can be estimated assuming a similar degree of fixity for deep foundations, but inherent errors will affect the accuracy of displacement estimation. This paper solves this problem expanding the 1 degree of freedom (1DOF) solution to a new 2 degrees of freedom (2DOF), to collect displacements under trains and enable cost-effective condition-based information related to bridge safety. Researchers developed a simplified beam to demonstrate the total displacement estimation using 2DOF and further conducted experimental results in the laboratory. The authors assumed linearity on properties and connections and used real train crossing event data as input to evaluate the accuracy of the proposed 2DOF method. The estimated displacement of the 2DOF model is more accurate than that of the 1DOF model for ten train crossing events. With only one sensor added to the ground of the pile, this method provides owners with approximately 40% more accurate displacements. Future work includes the study of nonlinearities and parametric study of the effect of resonance in displacement estimation accuracy for practical field implementation. The main application of this research is the optimization of the number of sensors and the simplification of sensor location, for lateral displacement estimation. Infrastructure managers can install a minimum number of sensors in tall piers or structures and determine the transverse displacement. The main practical aspect of this work is that engineers can collect the rotation at the base of the pier by locating sensors in the base. Using both the rotation both at the bottom and the top of the pier, the total displacement at the top can be obtained. In the practical domain, timber railroad piers could demonstrate additional lateral displacement under train crossing events not associated with the rotation above ground. Engineers could observe or collect that lateral displacement and add it to the total estimated displacement to obtain the total transverse displacement. Based on the field observations of the main author of this paper the lateral separation between the timber pile at the base of the pier is small, however it can be a practical next step in further development of the proposed method for practical applications. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wooden cantilever covered bridges are known for their marvelous shapes and manufacturing technique. Many wooden cantilever covered bridges were constructed during Ming and Qing Dynasties in Anhua province, China, due to the "Tea-Horse Trade" policy. The excellent performance of wooden materials and exquisite building techniques have kept these wooden bridges well-preserved and worthy of investigation. This paper conducted a comprehensive review of wooden cantilever covered bridges in Anhua, especially for the eight bridges listed as historical and cultural heritage protected at the provincial or the national level. The discussions covered the historical background of the bridges, their locations and dimensions, and the details of their structures including the cantilever systems, corridors, and roofs. Moreover, the cultural background was introduced to better understand the meaning of the decorations carved on the bridges and the logic of location selections. [ABSTRACT FROM AUTHOR]

Deck caps of bridges—in Germany shortly known as "bridge caps"—are usually made of steel reinforced concrete to form the anchoring area for the guardrail of bridge deck edges on existing cantilever slabs. Combined with protective devices, the outside arranged deck caps provide safety against lateral breaking or crashes of vehicles. Due to their exposed position in the cross section of bridges and the particularly intensive stresses, the deck caps are considered as wear parts and have to be renewed several times during the service life of a bridge. The decisive factor here is the discrepancy between the frost resistance of the concrete and the crack width restriction. On the one hand, only very small cracks (<0.2 mm) can be accepted to prevent corrosion of the rebars under the strong exposure of these elements. To confine crack widths without applying an excessively high degree of reinforcement, a low concrete compressive strength is advantageous. On the other hand, a sufficient frost resistance requires a correspondingly high compressive strength. With carbon reinforcement, these contrary points could be defused and simultaneously the needed durability could be provided. Therefore, slightly modified deck cap concretes combined with a carbon reinforcement mesh were tested to examine the bond behavior with and without freeze–thaw attack. To prove the characteristics of this combined system, the crack formation and crack distribution were investigated experimentally. The test results were compared to calculated values from a mathematically tool to be able to develop different reinforcement concepts in future that can ensure an optimized crack formation and crack width for deck caps. [ABSTRACT FROM AUTHOR]

The bridge of Shanghai Metro Line 10 over Metro Line 6 is a U-shaped concrete single-box double-cell concrete box beam continuous bridge. A novel method is applied to construct the asymmetric cantilever prefabricated and assembled continuous bridge due to the limited construction space and the complex environment. Four mechanical state control methods are applied during the T-shape structure construction process: tensioning pre-stressed steel strand, jacking by the axial force servo system, adjusting the leg reaction force, and setting the auxiliary leg. Auxiliary measures such as the compressive column, side-span counterweight, and temporary pre-stressing are also taken into consideration. The finite element method simulations are performed to measure effects of the four control methods during the construction process. The front leg force of the bridge erection machine and the deflection of the bridge are then monitored. It was deduced that the simulated and measured values of the cantilever T-shape structure are controlled within the limit range during the construction process. [ABSTRACT FROM AUTHOR]

Existing Niagara‐type concrete cantilever bridges, which in Italy are called Gerber bridges, suffer from degradation due to reinforcement corrosion and a consequent reduced load‐bearing capacity. The assessment of these structures is therefore an important part of the procedures for analyzing the state of existing bridges and any interventions required for their retrofitting. In particular, safety against failure of the half‐joint must be evaluated with respect to the behavior of the entire bridge and its state of conservation, determining what the conditions are that lead to failure, in terms of loads, state of stress, and possibly cracking state. This evaluation has to be carried out considering the configuration of the bridge through local and global models, in the presence of the crossbeam between the main girders or the prestressing tendons that can modify the behavior of the Gerber saddle, compared to that expected for a simple dapped‐end beam. To do this, it is necessary to combine the in situ investigations with reliable analytical and numerical models, which can correctly interpret the structural behavior of the bridge, determining the critical aspects for safety. The approach followed in this study was to combine the strut‐and‐tie models with nonlinear finite element models that can provide reliable information to the engineer who deals with the assessment and subsequently the conception of rehabilitation, in combination with in situ investigations and material tests. This was carried out through two different case studies in which the shape of the Gerber saddle, the presence of the crossbeam, and the presence of prestressing characterize the behavior and highlight the degree of safety and that of structural robustness. The results of the analyses carried out show that the presence of prestressing and a careful design with the use of large amounts of reinforcement can lead in some cases to high safety factors and consequently to a good level of robustness. They also show that the structural behavior can vary significantly according to the level of reinforcement corrosion: this is an aspect that can only be correctly assessed with the use of different models with different degrees of refinement. Finally, a proposal for global structural rehabilitation is presented by closing saddles, changing the static scheme to the continuous beam, and supplying external prestressing to strengthen the deck. [ABSTRACT FROM AUTHOR]

When building large composite bridges with steel cantilevers as supports for partial‐depth precast deck‐elements, currently there are only recommendations available, which based on experiences with regard to the fatigue stressed connections of the cantilevers. In a research project currently being worked on for the Federal Ministry of Transport and Digital Infrastructure (BMVI) appropriate recommendations are developed based on experimental tests, accompanied by numerical analyses and structural monitoring. The article provides an insight into the ongoing research work at the Technical University of Berlin. [ABSTRACT FROM AUTHOR]

The Brazilian code NBR 7188 for highway bridge design prescribes a live load model consisting of a 3-axle vehicle plus a uniform load, which are both affected by an impact factor when considering dynamic effects. It does not play out actual traffic static effects and may be, in some cases, non-conservative. This work presents two load model configurations developed by gathering a real traffic database, traffic simulations, modeling of the dynamic interaction between vehicles and structure, and statistical extrapolations. Proposed load models comprise dynamic effects and were calibrated for two-lane single carriageway bridges with span lengths up to 40 m under free-flowing traffic. The target values of the effects were compared to those generated by the new proposed load models, as well as by the Brazilian design load model. Adequacy of the proposed models is demonstrated; results show that the effects generated by the Brazilian design load model are underestimated in many cases, particularly for negative moments in cantilevers. [ABSTRACT FROM AUTHOR]

A patented Durable Redundant Joint (DRJ) concept featuring multiple adhesive load-paths, via a novel composite preform insert, is being considered for joining composite sandwich panel segments. Applications are wide ranging from spacecraft bus structure to launch vehicle primary structure (i.e. interstage cylinders and payload fairings). Numerical and experimental investigations were performed to assess the DRJ's performance. A fracture-based approach was used to evaluate this design. Ply-level mechanical properties for the material systems were generated, and a double cantilever beam coupon was designed and tested to estimate the Mode I critical energy release rate for the interface between two different composite prepreg material systems. The DRJ was tested and compared to testing of the more conventional splice joint (CSJ) design. Polytetrafluoroethylene (PTFE) inserts were used at the free edges of the joints to simulate debonds between the doubler and facesheet laminates. The DRJ coupons reached 32% greater in-plane tensile failure load compared to the CSJ coupons. Furthermore, the predicted increased strength for the DRJ design compared to the CSJ design was in remarkably good agreement with test data. Using the insight gained from these studies, three design attributes were investigated relative to increasing damage tolerance characteristics of the DRJ: (1) Insert stiffness, (2) Relative length between the doubler and the insert, and (3) The use of tapers at the ends of doublers. [ABSTRACT FROM AUTHOR]

Creep significantly affects the long-term deflection of the prestressed concrete bridge structure. Some models often used in predicting creep on concrete, such as ACI, AASHTO, and CEB, do not consider the water-cement ratio in the formula. The water-cement ratio is one of a factor in the magnitude of creep. If the water-cement ratio is excessive, the creep will also be significant. B3 Model uses the water-cement ratio in predicting creep in prestressed concrete bridge structures and has provided good accuracy with measured deflection data. This study compares the B3 Model with Model CEB 2010 to predict the effect of creep on long-term deflection. The bridge structure is modeled using Midas Civil 22 v1.2 software in this paper. The envelope displacement of the bridge B3 Model is more significant than CEB 2010. The prediction deflection of the B3 Model in 100 years of service life of the bridge is -16.34 cm, while CEB 2010 is -11.90 cm. Creep affects total deflection by 84% to 88%. Creep affects the deflection significantly because, in the construction process, each box girder segment is stressed and loaded at concrete age of 3 days. At the age of 3 days, the elastic modulus of the concrete is still not reached, and the cement paste on the concrete is still in the hydration process. The results showed a significant difference between B3 Model and CEB 2010. B3 Model predicts that the long-term deflection of the bridge until the end of the bridge's service life is 44% to 49% greater than the CEB 2010 model. The prediction of total deflection until the end of the service life bridge does not exceed the deflection limitation due to dead load determined by the codes of SNI and CEB. [ABSTRACT FROM AUTHOR]

Unnoticed corrosion in underground reinforced concrete structural members – such as foundations, retaining walls, or piles – may severely threaten the integrity of structures. However, condition assessment of the ground-buried structural parts is challenging, because the areas of interest are hardly accessible for visual inspection or non-destructive testing. An example of particular practical relevance is reinforcement corrosion at the back-side of the lower end of cantilever retaining walls, near the construction joint between stem and heel of the base slab. The collapse of a cantilever retaining wall in Austria was a tragic reminder of the dangers of unnoticed corrosion. The drawback of current inspection methods is that they are laborious and costly, but still, only a tiny fraction of the structure can be inspected. Considering that the degree of corrosion can vary significantly along a structure, such local information includes a risk that corrosion elsewhere remains undetected. A novel inspection system is proposed here, combining the well-proven half-cell potential measurement technique with steered horizontal underground drilling technologies. With this approach, a tailor-made probe is brought in proximity to the concrete surface in the soil and electrochemical measurements are performed to characterize the corrosion condition. The main advantage is that virtually the entire length of the structure can be inspected, thus overcoming the limitations of highly local inspection. Moreover, the proposed technique includes a method to constantly monitor the functionality of the potential measuring probe, based on electrical resistance measurements. The feasibility of the approach was confirmed in laboratory experiments on a mortar block in soil. These findings were confirmed in a field experiment. The results suggest that local corroding zones of practice-relevant size can be detected for a distance between the reference electrode and the steel surface of at least 25 cm. On the basis of this work, underground corrosion inspection of cantilever retaining walls is considered feasible, and the development of similar technologies as the one proposed here may in the future considerably enhance condition assessment of structures buried in the ground. [ABSTRACT FROM AUTHOR]

In order to solve the problem of self-energy supply of vehicle-mounted micro-sensors, bridge detection and some other low-power electronic devices in their working state, a vortex-induced flutter composite nonlinear piezoelectric energy harvester (VFPEH) with symmetrical airfoils on both sides of a cylindrical bluff body is designed. The VFPEH consists of a cantilever beam, a cylindrical bluff body connected to the free end of the cantilever beam, and two airfoil components symmetrically fixed at both ends of the shaft, which enables coupling between vortex-induced vibration and flutter. The airfoil symmetrically arranged on both sides of the cylindrical bluff body induces the cantilever beam to produce bending and torsional composite vibrations at high wind velocities, realizing energy harvest in the two degrees of freedom motion direction, which can effectively improve the output power of the energy harvester. Based on a wind tunnel experimental platform, the effect of key parameters matching impedance and the diameter of the cylindrical bluff body on the output performance of the VFPEH is investigated, together with the output performance of the classical vortex-induced energy harvester (VEH), the flutter energy harvester (FEH) and the VFPEH. The experimental results show that for the VFPEH under a combination of vortex-induced vibrations and flutter vibrations has a better output performance than the VEH and the FEH when using the same size. The coupling of vortex-induced vibration and flutter can reduce the start-up wind velocity of the VFPEH and expand the wind velocity range of the high output power of the VFPEH. The VFPEH has a better output performance at the cylindrical bluff body diameter of 30 mm and a load resistance of 140 kΩ. When the wind velocity range is 2 m/s–15 m/s, the maximum output power of the VFPEH is 6.47 mW, which is 129.4 times and 24.9 times of the maximum output power of the VEH (0.05 mW) and FEH (0.26 mW), respectively. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Akiyama atomic force microscopy probes represent a unique means of combining several of the desirable properties of tuning fork and cantilever probe designs. As a hybridized mechanical resonator, the vibrational characteristics of Akiyama probes result from a complex coupling between the intrinsic vibrational eigenmodes of its constituent tuning fork and bridging cantilever components. Through a combination of finite element analysis modeling and experimental measurements of the thermal vibrations of Akiyama probes we identify a complex series of vibrational eigenmodes and measure their frequencies, quality factors, and spring constants. We then demonstrate the viability of Akiyama probes to perform bimodal multi-frequency force sensing by performing a multimodal measurement of a surface’s nanoscale photothermal response using photo-induced force microscopy imaging techniques. Further performing a parametric search over alternative Akiyama probe geometries, we propose two modified probe designs to enhance the capability of Akiyama probes to perform sensitive bimodal multifrequency force sensing measurements. [ABSTRACT FROM AUTHOR]

Aiming at the problems of seedling injury and planting leakage due to the lack of seeding clamping force detection and real-time control in vegetable transplanting, a force feedback gripper was developed based on the linear Hall element. The mechanical properties of the stem of pepper cavity seedlings were first analyzed to provide a basis for the design of the gripper. A linear Hall sensor, a magnet, an elastic actuator, and an Arduino Uno development board make up the grasping force detecting system. Upon picking up a seedling, the elastic actuator, which is connected to the magnet, bends like a cantilever beam. As a result of the micro-displacement created by the elastic actuator, the Hall sensor's voltage changes and can be used to determine the clamping force. Detection avoids direct contact between the sensor and the cavity seedlings, reducing the risk of sensor damage. Finite element method (FEM) simulations were used to determine the initial spacing between the magnet and Hall sensor and the effect of the elastic actuator. Control commands are sent to the servo based on the gripping force collected by the Arduino Uno board. Finally, the functions of accurate measurement, display, storage, and control of the clamping force of the cavity tray seedlings are realized, so that the damage rate of the cavity tray seedlings is reduced. In order to explore the influence of the elastic actuators on the clamping force detection system and the performance of the force feedback gripper, a calibration test of the clamping force detection system and a test of the indoor transplantation of pepper seedlings were carried out. Based on the calibration test, the clamping force detection system has a sensitivity of 0.0693 V/N, linearity of 3.21%, an average linear coefficient of determination of 0.986, and a range of 10 N, which fully meet the clamping force detection accuracy requirements during transplantation. Indoor tests showed that the force feedback gripper was stable and adaptable. This study can provide a reference for detecting and controlling clamping forces during transplantation. [ABSTRACT FROM AUTHOR]

Considering the low accuracy and low efficiency of the traditional calibration method for base strain sensitivity of accelerometers, a novel base strain sensitivity calibration system with steady harmonic excitation is proposed. The required cantilever beam for calibration is driven by an electromagnetic exciter to generate a base strain varying in a steady harmonic pattern. By applying a Wheatstone bridge circuit, the generated strain with low distortion can be measured. The measurement system with a compensation function can automatically calibrate the base strain sensitivity. The amplitude linearity and frequency response characteristics of the base strain sensitivity in two accelerometers are obtained experimentally, and the uncertainty in the results is 2% (k = 2). [ABSTRACT FROM AUTHOR]