Search

In this work, we propose a variation of Miura origami which, different from the existing out-of-plane bending Miura origami, has an in-plane bent configuration due to its graded crease pattern. By combining with the one-way shape memory alloy spring, we show that the proposed graded Miura origami can serve as a smart actuator and can be applied to drive crawling robots or grippers. First, we constructed a physical model of the graded Miura origami, from which a curvature-programmable geometric equation is proposed. Then, in addition to providing a mechanical model that can capture the mechanical behavior of the initial force–displacement relationship of the curved beam, we show that the proposed curved origami has a different mechanical behavior compared to the corresponding simple flexible arch, specifically if realized by silicon rubbers. By arranging anisotropic friction to the feet, the origami robot can crawl with an omega-elongation/compression motion like an inchworm. With a closed-loop current source control system using a high-frequency pulse width modulation-based topology, where the strain state of the arched origami is detected by a demodulator-free fiber Bragg grating sensor, the average speed of the origami crawling robot can reach 2.72 mm/s. In addition, by arranging three graded Miura origami, a gripper capable of lifting a weight of 518.5 g can be formed, where the carried load is over 4.5 times its own weight. [ABSTRACT FROM AUTHOR]

This paper presents an arch structure called the circular box arch with sinusoidal corrugated webs (CBASCW). This study investigates the out-of-plane elastic buckling behavior and elastoplastic stability capacity of the arch through a combined approach of theoretical derivation and finite element simulation. The section stiffness of the arch, including flexural stiffness, shear stiffness, and torsional stiffness, is achieved through theoretical derivation. Additionally, the elastic buckling load in both pure compression and pure bending states is derived. A simplified model is also introduced, which can conveniently simulate the internal force and deformation of the arch. The elastoplastic instability mechanism and failure mode are studied under various loading conditions, including uniform radial load, end bending moment, vertical load uniformly distributed in full-span, and vertical load uniformly distributed in half-span. Furthermore, the stability curves of the arch under conditions of pure compression and pure bending are graphed by incorporating stability coefficient and regularized slenderness ratio. According to the simulation results obtained from the simplified model and the analysis of stability curves, a design formula for stability capacity is proposed. [ABSTRACT FROM AUTHOR]

The curved beam finite element approach based on the potential energy formulation is widely recognized as a versatile tool for lateral torsional buckling analysis of arches. However, there exist a variety of potentials, which were developed with distinct assumptions. The diversity of energy-based curved beam theories introduces confusions in practical applications. This paper aims to examine various potential energy formulations as to whether or not they obey the rigid body rule which is a prerequisite for valid second-order analysis. The induced moments at the ends of curved beam element that have been neglected from and/or the distributed moments that should be removed from available potentials are identified to help them become rigid body qualified. Based on the revised potential functional, a curved beam finite element formulation has been developed to effectively predict yet with less effort the out-of-plane critical load for circular and parabolic arches subject to various loading and constraint conditions. The results of numerical examples demonstrate that a potential energy formulation eligible for describing the out-of-plane behavior of curved beam is required to be rigid body qualified by fulfilling two aspects: (i) the neglected end moments that are imperative for satisfying the rigid body rule must be considered unless the virtual work done by them vanishes, and (ii) undesirable distributed moments that may be induced when undergoing the rigid body motion should be removed by considering all essential potential components. [ABSTRACT FROM AUTHOR]

In the study, a combined numerical simulation and on‐site monitoring method was used to analyze the asymmetric development characteristics of overlying rock fractures in a goaf under the condition of a goaf side entry formed by roof cutting and to explore the gas accumulation area in the goaf, achieving precise gas extraction from the goaf. The results demonstrates that a double‐balanced arch structure is formed under the condition of a goaf side entry formed by roof cutting, achieving safe retention of the roadway and showing the significance of the pressure relief effect of roof cutting. The collapse movement of the overlying rock on the roof‐cutting side is relatively advanced. The heights of the collapse zone on the roof‐cutting side and the uncut roof side are 28 and 24 m, respectively, and the development heights of the fracture zone are 37 and 42 m, respectively. The fault line on the roof‐cutting side gradually shifts toward the direction of the goaf, and the surface settlement and fracture development are relatively small. There is a clear asymmetric structure in terms of time effect, fault line, fracture zone height, and surface settlement compared to the uncut roof side. The gas is distributed throughout the entire goaf in the roof‐cutting and tunneling mode, and a high‐concentration gas accumulation area is formed near the open–off cut and working face on the high side of the fracture zone. Based on an actual situation, a method of drilling high and low positions in a fracture zone is proposed for extraction. Combined with on‐site monitoring, the goaf was no longer filled with gas during extraction, and the proportion of low‐concentration gas space considerably increased. [ABSTRACT FROM AUTHOR]

The Partially Concrete Filled Steel Tube (PCFST) structure has gradually been applied to bridges as the main load carrying components in recent years, owing to the advantages of light weight and high stability. The failure mechanism and load carrying capacity of PCFST structure highly depends on the concrete filling ratio. For this purpose, the failure mechanism and parametric analysis of a single arched PCFST cable stayed bridge tower are investigated by using both refined solid element simulation and quasi-static experiment. The results shows that the PCFST arched tower experiences asymmetrical instability failure subjected to quarter span symmetrical loading, and the plastic hinges appears firstly at the tower arch closely above the tower columns, and then the bottom of the tower columns, forming a rotating mechanism leading to the instability failure. Filling concrete or not will result in two opposite deforming propagations of the plastic hinges, and when the concrete filling length exceeds the length of plastic hinge, the initial rigidity and ultimate load carrying capacity of the PCFST structure will sharply increase. Finally, according to the results of the extended parametric analysis based on the real size simulation, an improved initial stress reduction coefficient of PCFST structure is then suggested. [ABSTRACT FROM AUTHOR]

After excavation of tunnels in interbedded surrounding rock, accidents such as rock peeling and arch crown collapse are prone to happen. In response to this issue, we first established an analysis model for the excavation of the interbedded surrounding rock tunnel through theoretical analysis, proposed corresponding failure criteria, and analyzed the reasons for the easy failure of the interbedded tunnel support structure based on the concept of principal stress difference. We also created interfaces in FLAC3D (version 6.0) software to restore the actual interbedded interface, verifying the effectiveness of principal stress difference in analyzing the deformation characteristics of the tunnel. Then, the instability forms of the interbedded surrounding rock tunnel were divided into two types, and effective support methods for the corresponding instability forms were proposed. Finally, based on the analysis results of the study, support was provided for the collapsed tunnel on site. A grouting large pipe shed was put to innovative use to support the tunnel arch waist, stabilizing the surrounding rock that is prone to shear slip and fracture at the upper part of the arch waist. The results indicate that the surrounding rock control effect is good. This study has a good reference value for on-site rapid construction and support design, and is of great significance for the instability prevention and control of interbedded surrounding rock tunnels. [ABSTRACT FROM AUTHOR]

In response to the issues of vibrations affecting the construction safety, speed, and accuracy of suspended structures due to dynamic disturbances during lifting, environmental disturbances, and improper operator actions, this paper investigates the application of the Active Rotary Inertia Driver (ARID) system for double-rope suspended structures, namely analyzes, and applies control to the vibration response of double-rope suspended structures under external excitations. Taking the double-rope suspended structure as an example, a dynamic analytical model of the double-rope suspended structure is established based on D’Alembert’s principle. Through shake table tests, the dynamic response characteristics and vibration control effects of the double-rope suspended structure under various external excitations are studied, and the influence of the twisting radius of the suspended structure on the control effect is analyzed. The experimental results show that the ARID control system achieves significant control effects on the swing and torsional vibrations of the suspended structure, which validates the accuracy of the theoretical model for the ARID control system and demonstrates its feasibility for practical applications. [ABSTRACT FROM AUTHOR]

The fast progress in electronic devices demands superior anti‐reflective performance of electromagnetic interference shielding materials. However, high‐performance shielding strategies are mainly dependent on reflection effects and this inevitably results in a trade‐off between shielding and anti‐reflective properties during structural designs. Herein, this work proposes a novel gradual heterogeneity design to fundamentally overcome the contradiction. The different steric hindrances in MXene nanosheets and aramid nanoclusters endow the competitively assembled laminal aerogel films with a unique Janus architecture. This Janus structure presents continuous gradient asymmetries and abundant cavities that enable prolonged energy attenuation paths and minimized reflection. Comparing to isotropic counterparts, the gradient design performances a 2174% reduction in reflection coefficient (0.0039) and a 53% increase in shielding efficiency (60.49 dB) in the terahertz band, both of which significantly outperform most state‐of‐the‐art anti‐reflective shielding structures. Moreover, the Janus architecture comprising interconnected arch‐shaped substructures provides the aerogel films with anisotropic EMI and thermal management capabilities, coupled with robust structural and performance stability. This work provides a conceptually novel platform for developing asymmetric architecture for advanced shielding materials. [ABSTRACT FROM AUTHOR]

Due to the complexity of construction sequence and the extended duration required to construct super large section tunnels, the selection of excavation method critically influences the stability of the surrounding rock and support structures. In this work, the Xiaoyuan Tunnel project in Jiangxi Province serves as the research background for employing ABAQUS software to simulate the variations in displacement and stress within the rock and support structures under three different excavation methods. The simulated results are subsequently compared and verified against monitoring data. The findings indicate that the three-benching seven-step method releases more stress (maximum principal stress value reaches 0.621 MPa) from the surrounding rock and support structures than the other methods, resulting in stress concentrations. Therefore, it is of vital significance to complete the initial support in time and seal the tunnel opening quickly. The maximum principal stress values caused by three excavation methods all appear at the arch foot position, highlighting the need for prompt reinforcement of stability support there. Compared to the CRD method and the three-benching seven-step method, the tunnel vault's settlement value caused by the double-side drift method is reduced by 14% and 19%, respectively. Furthermore, the largest disturbance of the surrounding rock occurs under the CRD method, while the double-side drift method minimizes such disturbances, making it the preferred choice for the construction of super large section tunnels. These insights are invaluable for guiding the selection and optimization of construction methods for such tunnels. [ABSTRACT FROM AUTHOR]

A three-lobed helical pipe was installed downstream of the bend of a vertical-horizontal pneumatic pipeline. The swirl characteristics under different helical pipe structures were investigated. Results show that: (a) the maximum velocity region rotates quasiperiodically, and the smaller the pitch, the faster the rotation; (b) the 3D morphological changes of the axial velocity distribution in downstream sections are similar: from an arch to a pit and finally to a uniform flat top. The tangential velocity appears as a Rankine vortex near the wall; (c) the swirl decays rapidly along the downstream. The initial swirl intensity, proportional to the helical pipe length, increases first and then decreases with decreasing pitch, whereas the structural parameters have minimal effect on the swirl decay rate; (d) the helical tube remarkably increases the system energy consumption, and the total pressure drop is inversely proportional to the pitch and proportional to the length. [ABSTRACT FROM AUTHOR]

SATB2‐associated syndrome (SAS, glass syndrome, OMIM#612313) is a neurodevelopmental autosomal dominant disorder with frequent craniofacial abnormalities including palatal and dental anomalies. To assess the role of Satb2 in craniofacial development, we analyzed mutant mice at different stages of development. Here, we show that Satb2 is broadly expressed in early embryonic mouse development including the mesenchyme of the second and third arches. Satb2−/− mutant mice exhibit microglossia, a shortened lower jaw, smaller trigeminal ganglia, and larger thyroids. We correlate these findings with the detailed clinical phenotype of four individuals with SAS and remarkable craniofacial phenotypes with one requiring mandibular distraction in childhood. We conclude that the mouse and patient data presented support less well‐described phenotypic aspects of SAS including mandibular morphology and thyroid anatomical/functional issues. [ABSTRACT FROM AUTHOR]

This work focuses on the bending examination of three-dimensional (3D) functionally graded carbon nanotube (CNT) reinforced composite (FG-CNTRC) cylindrical shell exposed to internal pressure. The composite cylindrical shell is assumed to be reinforced in the longitudinal axis. Mechanical properties of the constituents are applied based on the modified rule of the mixture. Distribution of CNTs across the shell thickness is assumed to be uniform and three types of functionally gradients. The governing equations are developed using the Principle of Virtual Displacements (PVDs) based on Carrera's Unified Formulation (CUF) and then differential quadrature method (DQM) is used to solve the governing equations for different combinations of simply supported and clamped boundary conditions. The comparison studies between the obtained results and those available in the literature demonstrate the accuracy and computational efficiency of the present formulation and method. The roles of different factors including the volume fraction of CNTs ( V CN * ), boundary conditions, distributions of CNTs, length-to-radius ratios ( L / r), and mechanical loads, are investigated in the outcomes. The results illustrate that the non-dimensional maximum deflections of functionally graded (FD) distributions are higher than the uniform distributions for different boundary conditions. [ABSTRACT FROM AUTHOR]

The structural elements of buildings have recently required the development of efficient design solutions due to increased dynamic and thermal loads. The main solution for improving the efficiency of such elements involves creating lightweight non-uniform beam and arch structures from alloyed steel, which has better mechanical characteristics. The most promising approach is the use of welded beams and arches with perforated partitions and composite beams, which are often used together, for instance, as structural elements of cylindrical shells. The development of an effective cross-sectional shape for perforated beams and crane girders is considered, taking into account the strength, local stability, resistance to flat bending, and fatigue deformation. It has been shown that the effective form for perforated beams is a box-shaped structure made of perforated shvellers. Calculations for selecting a rational design from the assortment of hot-rolled shveller profiles have demonstrated that a significant reduction in the weight of the structure can be achieved by using the proposed cross-sectional shape. An evaluation of the fatigue strength of composite metal crane girders operating in harsh conditions has shown the effectiveness of using hot-rolled I-beams as their upper flange, as well as the necessity of using hot-rolled I-beams to ensure strength in their lower part. When choosing the rational parameters of an arch design, multiple recalculations of its bending with respect to technological cutouts in the thickness are necessary; hence, simplified calculation schemes are commonly used. Some authors simplify this process by replacing an arch with a cutout with a solid arch reduced in height by the cutout radius. We have shown that this model does not accurately describe the actual distribution of forces and displacements, leading to inadequate results. We have developed a simplified methodology for the preliminary calculation of a circular arch with a cutout, which includes correction coefficients calculated by us. A calculation of the flat stress–strain state of an elastic circular metal arch with a central semicircular cutout under various ratios of design parameters and uniform external pressure was conducted. A dependence of the stress concentration coefficient at the cutout's apex on the ratio of the cutout radius and arch thickness was obtained. These results can be generalized for reinforced non-uniform shells and for the fuzzy application of external influences. [ABSTRACT FROM AUTHOR]

This technical note presents the optimal shape of an arch carrying a central point load to two pinned supports for maximum in-plane bifurcation buckling load. The arch shapes considered are triangular, parabolic, circular, catenary, and ogival. It is assumed that the arches are elastic and inextensible and their flexural rigidity is uniform throughout the arch length. The Hencky bar-chain model was used for elastic buckling analysis. It is found that the optimal arch shape depends on the arch apex height to length (h/L) ratio. The optimal arch shape changes from circular to catenary to parabolic and finally to triangular from h/L=0.1 to 1. This shows that the funicular triangular arch shape for the central point load is not the optimal arch shape against in-plane buckling when h/L is less than 0.528. For maximum buckling load, one may use either the circular, catenary, or parabolic arch with h/L approximately equal to 0.3. [ABSTRACT FROM AUTHOR]

The arching effect, which relates to load transfer and stress redistribution, is relevant in various aspects of the engineering field. However, understanding of the development and degeneration mechanisms of the arching effect in mesoscale remains limited. This paper presents discrete-element modelling (DEM) simulations of the 2D trapdoor test to investigate the arching effect in 2D granular materials with different porosity. Complex network theory is adopted for the analysis of mesoscale mechanisms of the development and degeneration of the arching effect. The results show that the variation of arching ratio with trapdoor displacement can be attributed to the evolution of arched force chains and particle contact force in a specific zone (where the vertical displacement of particles is larger than 0.1δ but <0.9δ). In this zone, the normal contact force between particles increases rapidly and robust force chains with large normal contact force are generated during the development process of the arching effect. This evolution of normal contact force and force chains becomes more obvious as the sample porosity decreases. During the degeneration process of the arching effect, the robust force chains in this zone are degenerated gradually, leading to the decrease of normal particle contact force at the microscale and the increase of arching ratio at the macroscale. [ABSTRACT FROM AUTHOR]

A stress–seepage–damage coupling model considering the long-term creep of a deep rock mass was established to study the mechanism of evolution of stability of the surrounding rock during reconstruction and excavation of abandoned deep water-rich roadways in a mine. The research shows that the maximum compressive stress in a circular cavern is significantly lower than that in a horseshoe-shaped cavern. Stress is distributed more uniformly in the circular cavern, and appropriately enlarging the size of the reconstructed excavation site can improve the stability of the surrounding rock. As the creep duration for abandoned roadways increases from 1 to 9 years, the growth rates for vault settlement and horizontal clearance convergence remain constant and the roadway undergoes steady-state creep. With increasing burial depth of the abandoned roadway (200–400 m), a pressure arch is gradually formed in the roadway roof in the reconstruction and mining process. The surrounding rock forms a 'self-bearing structure' with arch mechanical characteristics and a load transfer mechanism to maintain its own stability, and the overall bearing capacity of the surrounding rock is greatly improved. However, once the burial depth exceeds 400 m, the effect of the pressure arch begins to diminish with further increases in burial depth. Furthermore, porewater pressure significantly weakens the surrounding rocks. [ABSTRACT FROM AUTHOR]

The study presents an integration of cob with robotic processes. By challenging conventional monolithic earth-building methods, the study proposes the use of spatial nonplanar formations that are robotically fabricated, presenting an alternative geometric language for earth construction. The research methodology is derived from existing factors within the robotic lab, encompassing both constant and variable parameters. Through an experimental approach, the variables are systematically manipulated while observing the outcomes to identify patterns and relationships. Incremental refinements to the research conditions result in an optimal equilibrium state within the defined lab parameters. An empirical investigation approach serves as the foundation for controlling the printing process; wherein an iterative adjustment of the robot extrusion parameters is based on the behaviour of the deposited material. The outcome is several robotically printed cob nonplanar prototypes. Depending on their geometric formations and complexity, the printing process combined three variations: continuous, intervals, and modular. The latter enabled the production of a cob arch, serving as proof of feasibility for the creation of modular cob structures through a segmented assembly process. The study contributes to expanding the possibilities of cob construction by leveraging robotic technologies and paving the way for innovative applications of cob in contemporary architecture practices. [ABSTRACT FROM AUTHOR]

The steel rib and the lattice girder are two typical steel arch frames used in the primary lining of the New Austrian Tunnelling Method (NATM) highway tunnel. In the process of tunnel construction, it is necessary to choose the support method according to the mechanical properties, durability, construction difficulty, and economic benefits. In order to analyze the mechanical characteristics of steel arch frames, a loading and measurement test system for steel arch was designed, and destructive tests were carried out on a three-bar lattice girder, four-bar lattice girder, and I-beam steel rib. The steel utilization coefficient was introduced to compare the mechanical properties of the different types of steel frames. The results show that the I-beam steel rib has the largest steel utilization coefficient, but it is not well combined with concrete. Among the lattice girders, the three-bar W-shaped lattice girder uses the least amount of steel under the same load, which reduces the construction cost and is worth applying and popularizing. Additionally, the steel utilization coefficient of different types of lattice girders can be optimized through the ratio of steel bar diameters. It is proved that the steel utilization coefficient can provide a reference for the evaluation and selection of steel frames for the primary lining of highway tunnel engineering. [ABSTRACT FROM AUTHOR]

The emerging upward shield method (USM) for constructing vertical shafts has been used in various projects, including the Midosuji utility tunnel in Japan. A scaled-down model testing system, featuring a geometric similarity ratio of 1:30, was developed specifically for studying the USM. This system incorporates sand inflow control, propulsion control, data acquisition, and water level control. It facilitates detailed observation and recording of parameters such as vertical displacement of surface soil layers, support force at the excavation face, and earth pressure within the model box. Consequently, it enables investigation into the excavation face instability process, modes, and the formation and evolution of the soil arch zone above the excavation face during upward shield tunneling. Additionally, through the application of particle image velocimetry (PIV) technology and GeoPIV-RG software v1.1, quantitative analysis of soil displacement fields during excavation face instability is conducted, capturing microscopic displacements and deformations of soil planes. This approach more accurately elucidates the accuracy of understanding the dynamic response of soil. Pre-test research using the model testing system explores the variation patterns of excavation face load displacement, vertical earth pressure within the failure zone, surface displacement, and internal soil displacement during the instability process. Analysis reveals that excavation face load variation typically progresses through three stages: rapid growth, slow growth, and descent. Moreover, vertical earth pressure shifts upward in tandem with excavation face displacement, while overall surface displacement initially shows slight settlement followed by accelerated uplift. [ABSTRACT FROM AUTHOR]

The ground motion in the near-fault region of an earthquake is characterized by exceptional energy levels, powerful velocity impulses, substantial spatial variability, and notable permanent displacement. These unique attributes can dramatically escalate structural damage. Steel truss arch bridges, being critical components of transportation networks, are particularly vulnerable to these phenomena due to their extensive stiffness spans. Such factors are difficult to accurately simulate. In this study, real near-fault ground motions that incorporate spatial variability effects and pulse effects are used to excite the long-span arch bridge, thereby striving to realistically reproduce the structural damage sustained by the bridge under the simultaneous influence of near-fault spatial variability and pulse effects. This study adopts an arch bridge with a span closely approximating the spacing between stations (200 m) of the SMART seismic array as a case study. The near-fault ground motions, characterized by spatial variability and captured by the array, are selected as seismic samples, while the far-field ground motions recorded by the same array serve as a comparative reference. The seismic excitations are then input into the bridge case study, following the spatial correspondence of the stations, using a large-scale finite element program to obtain the structural response. Upon analyzing the seismic response of crucial positions on the bridge, it became evident that the arch foot of the bridge is more susceptible to the spatial variability in near-fault ground motion, whereas the vault experiences a greater impact from the high-energy velocity pulse. Specifically, under nonuniform seismic conditions, the internal force at the base of the bridge arch increased significantly, averaging a rise of 18.69% compared to uniform excitation conditions. Conversely, the displacement and internal force response at the top of the arch exhibited more modest increases of 6.48% and 10.33%, respectively. Under nonuniform excitation, the vault's response to near-fault earthquakes increased by an average of 20.35% com-pared to far-field earthquakes, while the arch foot's response rose by 11.55%. In contrast, under uniform excitation, the vault's response to near-fault earthquakes was notably higher, increasing by 25.04%, while the arch foot's response showed a minor increase of only 2.28%. The study has revealed significant differences in the sensitivity of different parts of long-span arch bridges to near-fault earthquake characteristics. This finding is of great importance for understanding the behavior of long-span arch bridges under complex earthquake conditions. Specifically, the arch foot of the bridge is more sensitive to the spatial variability of near-fault ground motions, while the arch crown is more significantly affected by high-energy velocity pulses, providing new insights for bridge seismic design. Furthermore, the differences in response between the arch crown and arch foot under different earthquake excitations also reveal the complexity and diversity of bridge structural responses. [ABSTRACT FROM AUTHOR]

Pre-existing concealed goafs underneath open-pit slopes (PCO-goafs) pose a serious threat to the stability of open-pit slopes (OP-slopes), which is a common problem worldwide. In this paper, the variable weight-target approaching method, equilibrium beam theory, Pratt's arch theory, and numerical simulation are used to analyze the management solutions and stability of five PCO-goaf groups in the Nannihu molybdenum mine located in Luoyang City, Henan Province, China. The five PCO-goaf groups, numbered 1#, 2#, 3#, 4#, and 5#, are divided into four hazard classes, ranging from extremely poor to good stability. The stability of 1#, 2#, and 4# is poor and must be managed by filling, and the design strength of backfill is 1.2 MPa; caving is used to treat 3# and 5#, and the safe thickness of the overlying roof is calculated to be 10.5–41 m. After treatment, the safety coefficient of the slope is greater than 1.2, indicating that the slope is stable. This study provides insight and guidance for the safe operation of open-pit mines threatened by the existence of PCO-goafs. [ABSTRACT FROM AUTHOR]

Characterized by long spans, low aspect ratios, and intricate construction sequences, super-large cross-section tunnels present substantial construction risks. Therefore, the selection of the optimal excavation method and construction sequence is crucial for ensuring the safety of tunnel construction and minimizing project costs. This paper takes a super large transverse-section highway tunnel as a case study, employing field monitoring data combined with ABAQUS software to analyze the stress and deformation of surrounding rock and support structures under different excavation methods. The findings reveal that the deformation of surrounding rock and support structures excavated by the Double-Side Drift Method is smaller than those caused by the three-benching seven-step method and the CRD excavation method. Nevertheless, the significant stresses of surrounding rock and support structures are released by the Double-Side Drift Method, leading to potential stress concentrations. Thus, it is necessary to ensure the rapid completion of early support and quick sealing of the tunnel. Furthermore, the sixth process achieves smaller deformation (including arch displacement and surface settlement) of the tunnel, a shorter construction period, and lower economic costs when compared to other construction processes. Consequently, it can obviously be concluded that both the Double-Side Drift Method and the sixth construction process stand out as the most appropriate choices for excavating super large cross-section tunnels. The insights obtained from this study provide theoretical guidance for the design and construction of similar tunnel projects. [ABSTRACT FROM AUTHOR]

This document provides an overview of the advancements in energy harvesting technologies and their integration into the Internet of Things (IoT) and wireless sensor networks. It includes 31 papers covering various energy harvesting devices, optimization techniques, and potential applications. The research aims to improve the efficiency and sustainability of wireless sensor networks while minimizing energy consumption. The articles explore different methods of energy harvesting, such as solar, thermal, vibrational, and radio frequency energy, and discuss their application in various fields, including wearable devices, solar energy harvesting, and IoT-enabled smart meters. Overall, this collection offers a comprehensive overview of the current research and advancements in energy harvesting for sensor networks. [Extracted from the article]

To investigate the effects of long-term prestress loss on concrete box girders strengthened with external prestressing, a large-span box girder, in service for over 20 years and strengthened with external prestressing, was monitored for four months. Prestress loss in the longitudinal, vertical, and transverse directions of the box girder was calculated according to Chinese code requirements. Magnetic flux rope force transducers were used to monitor the prestress loss in the external prestressing cables. Fiber Bragg Grating (FBG) sensors were used to monitor deflection changes at the mid-span of the bridge. Finally, the effect of prestress loss in the longitudinal, vertical, and transverse tendons on mid-span deflection was investigated through simulations using ABAQUS software. The results show that instantaneous prestress loss accounts for most of the total loss compared to long-term loss, and that longitudinal prestress loss has the most significant effect on mid-span deflection. The impact of longitudinal prestress loss on deflection before and after strengthening was also compared. The downward deflection and up-ward arch caused by longitudinal tendon prestress loss were reduced after strengthening, con-firming the effectiveness of the external prestressing method. [ABSTRACT FROM AUTHOR]

The adoption of three-dimensional (3D) imaging technologies in orthognathic surgery led to the development of virtual surgical planning and printing of patient-specific orthognathic surgical splints (OSSs). The accuracy and precision of 3D printed OSSs are considered important; however, there is limited data in the literature regarding whether the type of resin materials may influence these measures. A virtual OSS was created using a set of typodont models and printed in Biomed Clear, Dental LT V2, and Surgical Guide resins (Formlabs, Somerville, MA, USA), using a stereolithography printer. The upper intercanine width, intermolar width, and arch length were analysed. Differences between the reference dimensions of the virtual splint and the corresponding mean measurements of the 3D-printed splints were mostly considered clinically acceptable. The greatest variation was observed in the arch length for all 3 materials, which relates to the Z-axis of the printer; only 33.3–66.7% of OSSs were within the tolerance limit of ±0.1 mm quoted by the manufacturer. The Surgical Guide group demonstrated the highest degree of accuracy and precision overall. Further research would help to assess the 3D accuracy and precision, explore the variation found between different resin materials used, and confirm the findings of this research. [ABSTRACT FROM AUTHOR]

This paper presents an innovative strategy to address the issues of clogging and cluster-related challenges in microchannels within microfluidic devices. Leveraging three-dimensional (3D) microbubble streaming as a dynamic solution, our approach involves the controlled activation of microbubbles near channel constrictions, inducing microstreaming with distinctive features. This microstreaming, characterized by a high non-uniform 3D gradient and significant shear stress, effectively inhibits arch formation at constrictions and disintegrates particle clusters, demonstrating real-time prevention of clogging incidents and blockages. This study includes experimental validation of the anti-clogging technique, a detailed examination of microstreaming phenomena, and their effects on clogging and clustering issues. It also incorporates statistical analyses performed in various scenarios to verify the method's effectiveness and adaptability. Moreover, a versatile control system has been designed that operates in event-triggered, continuous, or periodic modes, which suits different lab-on-a-chip applications and improves the overall functionality of microfluidic systems. [ABSTRACT FROM AUTHOR]

Catastrophe theory was used to establish a safety assessment model to reduce the reliance on subjective judgments in evaluation of timber-framed heritage buildings. This study was conducted in three phases. Initially, a comprehensive evaluation index system was established from the perspective of foundation. It consisted of eight aspects and 25 safety evaluation indicators using superstructure load-bearing elements, maintenance structures, and their interconnections in timber-framed heritage buildings. The 25 safety evaluation indicators included foundation, base, stone piers, columns, beams, lintels (beams, pads, and other bending components), bracket sets, arches, maintenance walls, beam-brace connections, and roof structures. The bottom-level indicators in the index system were dimensionless. The second phase employed typical catastrophe models (cusp, swallowtail, and butterfly) for normalization, resulting in calculated catastrophe scales and evaluation levels. The case study of the Buddha Hall of Zhihua Temple, Beijing, was applied in the final phase. It was found that the catastrophe scales method solved the subjectivity issues in determining weights. Additionally, the calculations were found to be concise and reliable, providing accurate results. The model can be used as a theoretical reference for the future safety assessment of timber-framed heritage buildings. [ABSTRACT FROM AUTHOR]

Arch and serpentine structures are two fundamental structural forms with significant applications in various fields. When subjected to compressive loading at both ends, these structures undergo flexural-torsional post-buckling, resulting in complex deformation modes that are challenging to describe using basic functions (e.g., trigonometric functions and polynomial functions), posing significant challenges in finding analytical solutions. In this study, we propose a novel approach to address this issue. By representing the lateral displacement with a trigonometric series expansion and utilizing the equilibrium equation, the angular displacement is expressed in terms of special functions known as Mathieu functions. Furthermore, the energy method is employed to obtain analytical solutions for the flexural-torsional post-buckling deformation components. The theoretical findings are validated through experiments and finite element analysis. Based on the theoretical results, explicit analytical expressions for the maximum principal strain and the bending-torsion ratio of the structures are derived, offering valuable insights for the design of arch and serpentine structures in practical applications. [ABSTRACT FROM AUTHOR]

The elastic solutions of isotropic complex noncircular deep or shallow tunnels are obtained by the complex variable theory in this paper. In the solution procedure, the mapping function in the form of power series is adopted and Cauchy integral formulas are widely applied to simplify the calculation. The unified solutions expressions for the mapping function with any number of series terms (namely the solving accuracy) are presented. When the terms number of the mapping function is determined, the solutions are accurate for the tunnels considering the influence of local rock gravity, as they are derived by analysis without any approximation and numerical method. Compared to previous analytical method that maps tunnels and surface boundary to rings, the surface boundary conditions of this method are not fully satisfied but the coefficients of the mapping function used are easier to solve, requiring fewer series, and the solution process is simpler and faster. Therefore, it is more suitable for deep and shallow rock tunnels that are not near the surface. Semi-circle arch, three-centered arch, horseshoe shape, asymmetric trapezoid and 'C' shape tunnels are analyzed as examples, and the validity of the results is verified by comparing the analytical solution obtained with the FEM numerical solution calculated in ANSYS software. Highlights: Elastic analytical algorithm for shallow rock tunnels with complex shapes is proposed. Solutions proposed are valid for the mapping function in power series form with any number of terms. The impact of tunnel asymmetry is considered in this study. High-accuracy solutions for tunnels with complex shapes are obtained by controlling the number of mapping function terms [ABSTRACT FROM AUTHOR]

This study aims to analyze the in-plane free vibrations of arches comprising the laterally symmetric functionally graded materials. Emphasis is placed on the circular arch whose material properties vary laterally symmetrically about the centroidal axis by a power-law function. The differential equations governing the mode shape of the arch were derived under the boundary conditions and were numerically solved to calculate the natural frequencies using the Runge–Kutta and Regula–Falsi methods. Calculation results of this study for natural frequencies compare well with those of the finite element method. The effects of various arch parameters on natural frequencies are highlighted and discussed in detail. [ABSTRACT FROM AUTHOR]

Existing studies have evidenced that mobile-assisted vocabulary learning, which allows students to create artefacts and engage in productive skills, can help them in vocabulary learning. However, there remains little research and validated approaches for designing seamless vocabulary learning experiences for young learners. In this paper, a seamless vocabulary learning system was specifically designed for young learners. The study involved three classes of primary 2 students to investigate the learning effectiveness of seamless vocabulary learning, with a focus on analyzing student-generated artefacts. The results validated the effectiveness of seamless vocabulary learning for young learners, emphasizing the importance of strengthening the connection between home-based learning and classroom-based learning. The study also indicated the pivotal role of providing students with opportunities to improve their artefacts constantly across different learning contexts. [ABSTRACT FROM AUTHOR]

Under seismic loading, corroded reinforced concrete (RC) columns are prone to brittle shear failure, which poses a significant threat to existing structures. However, due to the mechanical defects and insufficient parameters included in the equations available in codes, the literature exhibits a lack of precision in predicting the shear strength of such columns. In this paper, a shear strength equation for the RC column was established based on the truss-arch model theory. On this basis, the effect of corrosion on key parameters such as the cross-sectional area of rebar, yield strength, compressive strength of concrete, and displacement ductility was fully considered to establish the shear strength equation of corroded RC columns. To assess the accuracy and applicability of the proposed equation, a database consisting of 215 specimen parameters was compiled. Comparative analyses were conducted with existing equations from the literature. The results indicate that the mean values and coefficient of variation for the ratio of calculated values to the tested values of the equation were 1.098 and 0.601, respectively, which proves the equation's high computational accuracy and low dispersion. Consequently, the proposed equation offers a more effective calculation method for predicting and assessing the shear strength of corroded RC columns. This method holds significant potential for enhancing the resilience of structures in seismic-prone regions. [ABSTRACT FROM AUTHOR]

This article investigates the out-of-plane buckling of functionally graded porous I-shaped circular arches with graphene platelets reinforcements in a uniform temperature field. The accurate expressions of the prebuckling internal forces owing to thermal expansion are derived. The theoretical out-of-plane buckling temperature difference is obtained by the Ritz technique and is verified by finite element results. Notably, with the asymmetrical distribution of pores along the height of the section, the monosymmetry parameter is considered in the out-of-plane buckling energy equation. The effects of graphene platelets weight fraction, porosity coefficient, and porosity distribution patterns on buckling temperature difference are analyzed in detailed. [ABSTRACT FROM AUTHOR]

Strengthening planning for the Chemnitz Viaduct from the perspective of the checking engineer The Chemnitz Viaduct was built for four‐track traffic with a length of 275 m between 1901 and 1909. After 120 years of use, it had to be technically repaired and strengthed for the use for another 80 years. The bridge consists of four parallel superstructures, each spans over two arches and ten beam bridges. For future double‐track traffic, the two inner superstructures were equipped with tracks for rail traffic, and the two outer superstructures were used for side and emergency sidewalks as well as for technical equipment. For this purpose, the inner beam bridges were replaced and designed as a steel composite structure. The substructures and other superstructures were largely preserved in accordance with the requirements of monument protection and renovated or replaced in small parts as necessary. Particular attention was paid to preserving the large number of historical steel bearings. The structural implementation of this complex project under "rolling wheels" required special measures for ongoing railway traffic. In this article, after an overview of the historical building and its assessment, the work in the advisory board is discussed and the handling of various measures for technical repairs and strengthenings, taking into account the monument protection in conjunction with the additional necessary permits and approvals. [ABSTRACT FROM AUTHOR]

Background: Digital image correlation (DIC) has been widely used for motion tracking and estimation, however, the process is often sensitive to the initial guess, especially under large translations and rotations. Objective: To provide novel and effective solutions for the DIC in measuring large translations and rotations. Methods: A ring-projection-based two-scale approach is proposed. In the integer-pixel scale, a novel ring projection scheme, including amplitude and phase correlations of the rings, is developed to quickly get the integer-pixel initial estimation of the translations and rotation. In the sub-pixel scale, the gradient-based inverse compositional Gauss-Newton (IC-GN) algorithm, which is free from repeat computation of Hessian matrix, is adopted to efficiently get the optimal motion parameters. Results: The numerical example show that the absolute error is no more than 0.05 pixel for measured large translations and no more than 0.05 ∘ for measured large rotations. While test experiments on a rotated blade and a flexible arch demonstrate the effectiveness, accuracy and applicability of the proposed approach in measuring the rotating motion, flexible large deformation and vibrational modal parameters of structures. Conclusions: The ability and effectiveness of the proposed approach for large translations and rotations measurement have been verified. Since large deformations and rotations are frequently encountered in rotating and flexible structures, the proposed approach is believed to constitute a feasible and powerful tool for static and dynamic deformation measurement of these structures. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the stability of rocky slopes largely formed of sandstone and claystone clastics along Highway 80-2 in Mosul City, northern Iraq. Seven separate stations along the route were covered by the investigation, and each station included two to five study locations. Field studies were used to identify both man-made and natural slope failures caused by building a residential complex. The identification of these slopes' sliding surfaces was done using a user-friendly, contemporary method, with the potential for future advancements in measuring safety parameters. According to the analysis, the sliding potential is raised, especially during rainy seasons, by geotechnically weak rocks. Examples of these rocks include sandstone and claystone. The most important assumption underlying the suggested approach is a circle-shaped arch that is centered at the point where a vertical line from the slope's toe intersects the upper slope level. The sliding base is represented by the diagonal line inside the effective range of the slope, which relies on the angle of internal friction and is equal to the horizontal distance twice the vertical height of the slope. The angle of internal friction for most clastic slope materials was determined to be 27°. The slope inclination was used to determine the shape and sequence of sliding surfaces. As a result of the study's findings, it can be concluded that the suggested model accurately predicts the slides seen in the study area. [ABSTRACT FROM AUTHOR]

The h-type pile (hTP pile) is a complex anti-slip pile system, which connects the front pile and the back pile through beams. When it is used in engineering, there is a complex soil arch effect between the soil and the hTP piles, which makes the complex anti-slip mechanism. In this paper, the discrete element method is used to establish the hTP pile models, analyze the displacement and stress distribution law of the soil body and investigate the spatial distribution and variation patterns of soil arches, this can provide a basis for the design of hTP. The results indicate that the soil arch structure formed under the displacement between hTPs can be divided into four stages: initial stage, development stage, overlapping stage and stable stage. The development speed of the soil arch between the rear piles is slower than that of the soil arch between the former piles. As the depth of the soil increases, the arch line of the soil arch gets closer to the rear pile. The soil arch of the stress between hTPs can be divided into initial stage, development stage and stable stage. The time step corresponding to the stable stage of the stress in the horizontal direction is equal to the sum of the horizontal displacement generated by the overlapping stage and the stabilization stage. The stress of the soil slope gradually decreases and extends from the surface to the bottom layer of the slope. Soil arches appear on the rear side of both the front and rear piles at different anti-slip pile spacings, and they all tend to overlap. The increase in pile spacing does not have a significant effect on the ratio of soil arch height and soil arch span, and the evolution of soil arch is similar between hTP at different pile spacings. All above can provide reference for the application and design of hTPs. [ABSTRACT FROM AUTHOR]

To achieve sustainable desalination and water purification, solar interface evaporation technology is an effective means due to its high energy efficiency. Reasonable photothermal conversion materials and surface design are crucial for the interfacial solar evaporation process. How to design water transport routes and thermal insulating layers simultaneously is one of the major challenges to solar interface evaporation technology today. Herein, this work reports an arch-shaped wood evaporator (pine@carbon black (CB)-metal-organic framework-801 (MOF-801)-36%) for efficient, fast and continuous interfacial solar evaporation, which is composed of an arch-shaped wood substrate, MOF-801, and CB as a light absorption layer. The arch-shaped structure has a double-sided evaporation effect, which has a synergistic effect on augmenting solar evaporation efficiency. In addition, the in-situ growth of MOF-801 in pretreated wood microchannels renders the wood evaporator a significant function of reducing the equivalent enthalpy of evaporation due to the reduction of the hydrogen bonding density of water molecules as they pass through the wood channels. The best evaporation rate of the arch-shaped wood evaporator can reach 2.535 kg·m−2·h−1, and the efficiency reaches 93.7% under the irradiation of 1 sun illumination. Notably, it could be used for desalination and wastewater treatment to collect fresh water that meets drinking requirements set by the World Health Organization (WHO). This integrated evaporator provides an efficient way for commercial portable photothermal conversion and new ideas for advanced solar-driven water treatment technology. [ABSTRACT FROM AUTHOR]

Background: Os naviculare in general alters the functional and anatomical balances of the longitudinal plantar arch. A substantial number of the posterior tibialistendon fibersinsert on the accessory ossicle instead of its insertion on tarsal and metatarsal bones resulting in unbalanced stress forces on the tendon. The presence of an accessory navicular type II or type III is a risk factorfor PTT tendinopathy and possible PTT tear. Methodology: In this single subject case study, the participant reported with the pre-diagnosed Os naviculare. On examination at initial presentation, the navicular tuberosity of the affected foot was prominent as compared tothe contralateral limb. The site was tender on palpation. Ankle range of motion was within normal ranges except ankle dorsiflexion was slightly compromised. Mild pain on active and resisted was noted. Functional tests like star excursion balance test, single leg standing could not be performed due to pain. Pre and post protocol assessment was graded and measured on Cumberland ankle instability tool. The tenderness was recorded using numeric pain rating scale. Star excursion balance test was performed one on 8 th day and post protocol. MWM was performed at distal tibiofibular joint on 6 days every week for 3 weeks alongside the conventional regime exercises and ultrasound was applied post treatment session. Result: Result of this study suggested that addition of MWM of distal tibiofibular joint in theconservative exercise protocol was effective in the reduction of pain, dysfunction and improveddynamic control. Conclusion: The results of this study suggests that the addition of MWM of distal tibiofibular joint alongside conservative management shows appreciable effect in improving dysfunction, dynamic stability and reducing pain in individual with congenital Os naviculare. [ABSTRACT FROM AUTHOR]

For a 300 MWe anthracite- and arch-fired boiler with biased-swirling-secondary-air (BSSA) technology, the distribution law of gas/solid two-phase velocity in the furnace is obtained with the help of a 1:10 cold modeling experiment bench, and the combustion and NOx formation characteristics in the furnace are revealed by numerical calculation. The results show that, with the increase of over-fire air rate, the reflux velocity in the reflux zone under the arch decreases continuously, and when the main air flow from the furnace arch reaches the staged air region from the vent air region, the position of particle flow in the primary air turn upward is advanced, and the utilization rate of the space in the lower furnace will decrease continuously. In the regions of vent air and staged air, when the over-fire air rate increases from 15% to 25%, the maximum vertical velocity decreases by approximately 2 times, and the downward depth of air flow from the furnace arch decreases significantly. When the over-fire air rate is increased from 10% to 25%, the thermal resistance between the primary air of the burner and the high-temperature flue gas in the furnace center increases, the ignition of the primary pulverized coal air flow is advanced, the flue gas temperature in the center of the lower furnace is decreased. As a result, with the increase of over-fire air rate, the combustible content of fly ash increases continuously. Especially, when the over-fire air rate increases from 20% to 25%, the combustible content of fly ash increases significantly. With the increase of the over-fire air rate, the high CO concentration region in the primary combustion zone expands, the reducing atmosphere is strengthened, the formation of NOx is effectively restrained, and the NOx emission concentration at the furnace outlet continues to decreases. In particular, when the over-fire air rate increases from 15% to 20%, the NOx emission concentration decreases greatly. After the swirling secondary air of the arch-fired boiler is biased, the setting of over-fire air rate is recommended to be 20%, and the NOx emission concentration and combustible content of fly ash are 694 mg/m3(O2 = 6%) and 7.32%, respectively. Compared with a traditional swirling arch-fired boiler, the combustible content of fly ash and NOx emission concentration are reduced by 46.8% and 34.1%, respectively. [ABSTRACT FROM AUTHOR]

Efficient monitoring and recognition of movement are crucial in enhancing athletic performance. Traditional methods have limitations in terms of high site requirements and power consumption, making them unsuitable for long-term tracking and monitoring. A potential solution to low-power monitoring of body area networks is triboelectric sensors. However, the current analysis method for badminton triboelectric sensing data is relatively simple, while flexible, triboelectric sensors based on 3D printing face issues such as discomfort when joints are bent or twisted in a large range. In light of this, a flexible arch-shaped triboelectric sensor based on 3D printing (FA-Sensor) is proposed. By combining neural network algorithms with the signal acquisition module and the master computer, an intelligent multi-sensor node system for badminton monitoring is established. The FA-Sensor exhibits high sensitivity to bending and twisting motions due to its elastic TPE shell and arched shape design. It minimizes interference with human motion during bending (10°–150°) or twisting (20°–100°) over a wide range. The peak output voltage of the FA-Sensor demonstrates a clear functional relationship with the bending angle, exhibiting piecewise sensitivities of 7.98 and 29.28 mV/°, respectively. For seven different parts of the human body, it can be quickly customized to different sizes, with stable and repeatable response outputs. In application, the badminton sports monitoring system enables real-time feedback and recognition of four typical technical movements, achieving a recognition accuracy rate of 97.2%. The system enables athletes to analyze and enhance badminton technology while also exhibiting promising potential for application in other intelligent sports domains. [ABSTRACT FROM AUTHOR]

The accurate installation of long-span arch bridges' arch ribs remains a challenge due to the complex calculations required for cable forces and arch rib displacements, as well as the significant influence of environmental and construction loads. In this study, we propose a practical approach to alignment and error feedback control for long-span arch bridges. Cable forces were optimized using multiple control objectives based on influence matrix principles. The impact of temperature on the next segment to be installed was analyzed using the metastatic GM(1, 1) model and fitting results. Several tunable parameters were employed to account for parameter errors and environmental interference. These parameters were adjusted based on the deviations between practical and theoretical alignments for different arch rib segments, achieving a model output of an offset-free-tracking arch rib structure. This technology was applied to monitor the construction of the Tian'e Longtan Grand Bridge. Compared to conventional alignment control approaches, the proposed method achieved excellent arch ring alignment after the closure of the high-accuracy arch rib and cable release, as well as effective control of cable force uniformity and tower deviation. Field measurement data indicate that the closing deviation of the arch ring is only 3 mm. This study provides a valuable reference for the construction control of long-span arch bridges. [ABSTRACT FROM AUTHOR]

Aluminum alloy frame is a novel structure system developed in recent years. In this article, the load-bearing performance of the beam-beam joint of the aluminum alloy frame is studied through numerical analysis and experiment and a safety monitoring method is developed. The impacts of the arch angle and bolt diameter on the beam-beam joint mechanical characteristics are explored through experiments under vertical load. When the diameter of the bolt was increased, the load-bearing performance of such joint displayed a pattern of first increasing and then decreasing. As the arch angle increased, the load-bearing performance on the joint gradually improved. Based on the experiments, numerical analysis models varying in arch angle were established, and the impacts of arch angles on the stiffness during the yield stage, ultimate load, and elastic stiffness of the aluminum alloy portal frame (AAPF) beam-beam joints were further explored through numerical simulation of the structure under vertical and horizontal loads. When the arching angle was increased, the elastic stiffness and yield stiffness of the beam-beam joint under vertical load showed a pattern of first increasing and then decreasing. When the arching angle was increased, the elastic stiffness and yield stiffness of the beam-beam joint under horizontal load significantly decreased. Based on the mechanical properties, a safety monitoring method for AAPF beam-beam joints based on displacement monitoring and frequency monitoring is proposed. [ABSTRACT FROM AUTHOR]

The primary aim of this research was to delimitate the final pit in an open pit mine using the 1×5 and 1×9 arch methods of the pseudoflow maximum flow algorithm. To achieve this, Exploratory Data Analysis (EDA), economic, and geomechanical parameters were utilized. Various final pit scenarios were generated by varying the revenue factor. The analysis was conducted using Python 3.11 (Jupyter Notebook) and SGeMS V.3.0 software. The block model comprised 480,000 blocks, each measuring 10×10×10 meters, with a copper grade range from 0 to 1.41%. Specific parameters were employed, including a slope angle of 45°, a base copper price of 3.90 US\$/lb, and smelting, extraction, and crushing-grinding costs of 0.40 US\$/lb, 2.30, and 11.00 US\$/ton, respectively. Twenty final pits were generated for each method, based on a revenue factor from 0.10 to 2.00. The results indicated that both methods are effective for final pit delineation, with the 1×5 method achieving an NPV of 17,855 MUS\$ and a REM of 0.27, and the 1×9 method attaining an NPV of 18,456 MUS$ and a REM of 0.35. It was concluded that the 1×9 arch method is preferable as it yields a higher NPV. This study underscores the importance of methodological selection in the planning of open-pit mines, demonstrating that despite a higher REM, the 1×9 method significantly enhances the NPV, implying substantial economic benefits for the industry. [ABSTRACT FROM AUTHOR]