Arbitrary Bending Research Articles

Nickel-Iron Interfacial Alloy Nanoparticles Encapsulated By Pyridinic-N Enriched CNT on Carbon Fiber Cloth for Bifunctional Oxygen Catalysts and Biaxially Flexible Zinc-Air Batteries

Low-price, high-performance, and long-term stability electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly significant in the application of rechargeable zinc air batteries. In this study, we report a highly reversible bifunctional electrocatalyst for flexible Zn air batteries featuring pyridinic-N exclusively enriched carbon-nanotube-encased nickel-iron (NiFe) interfacial alloy nanoparticles derived from an LDH template on knitted carbon fiber cloth. NiFe nanoparticles are catalytically released from the NiFe-MOF to form CNT tentacles when pyrolyzed in an inert atmosphere. XPS and XAS studies revealed the dominating presence of pyridinic-N, which reduces electron localization around NiFe centers and improves the interaction with oxygenated species. As a result, the NiFe-N-CNT-KCC catalysts exhibited a low operating overpotential (η10) of 173 mV for the OER and a half-wave potential (E1/2) of 0.87 V for the ORR, superior to benchmark electrocatalysts. As an air cathode for zinc-air batteries, the NiFe-N-CNT-KCC-based battery showed excellent electrochemical performance, with an open circuit voltage (OCV) of 1.55 V, high power density (153 mW cm-2), excellent specific capacity of 793.2 mA h g-1, and long-term stability. Most impressively, the solid-state flexible zinc-air battery with the NiFe-N-CNT-KCC cathode showed admirable rate performance and exceptional mechanical stability under arbitrary bending and twisting conditions, holding great potential in practical implementation in next-generation high-power and high-energy-density batteries, even with the potential for wearable applications.

Mangosteen husk-derived porous carbon for quasi solid-state supercapacitor with advanced performances

Exploiting advanced electrode materials and electrolytes are two fundamental approaches to enhance the electrochemical performances of supercapacitor. Herein, mangosteen husk-derived porous carbon (MHPC) and KOH gel-electrolyte are prepared and applied in quasi solid-state supercapacitor. In coin-type supercapacitor employing 6 M KOH gel-electrolyte, the MHPC electrode exhibits a high specific capacitance of 285 F g−1 at a current density of 0.2 A g−1, coupled with exceptional cyclability, retaining 88.9 % of its initial capacity after 10,000 cycles. Additionally, the elaborated MHPC electrode and 6 M KOH gel-electrolyte enabled the flexible device in maintaining superior capacitive properties under arbitrary bending angles. Our findings present an avenue in the development of cost-effective and highly safe energy storage devices.

Virtual Fresnel drag in spatiotemporal transformation medium.

A moving dielectric medium can modify the propagation of light by adding an extra velocity in the direction of the medium's motion, a phenomenon commonly referred to as Fresnel drag. However, moving dielectric slabs typically result in boundary reflections and cannot drag light when their refractive index approaches unity. In this study, we use a more intuitive geometrical method to explore the drag effect within the conceptual framework of a virtual moving geometry-a space with impedance matched to the air, thereby precluding the occurrence of boundary reflections. Subsequently, we demonstrate that the virtual moving geometry can be realized by a stationary bianisotropic spatiotemporal transformation medium utilizing transformation optics. This medium incorporates both spatial and temporal degrees of freedom, providing it with enhanced flexibility and functionality for the manipulation of electromagnetic waves, such as arbitrary reflectionless bending (achieving a virtual Fresnel drag effect), nonreciprocal transmission, and the induction of a virtual Doppler effect. Ultimately, we apply the spatiotemporal transformation medium to design a nonreciprocal reflectionless field shifter and a nonreciprocal invisibility cloak. The introduction of a virtual moving geometry to design the spatiotemporal transformation medium can serve as theoretical support for the rapidly evolving field of time-varying metamaterials.

Visually encoding orthogonal planar graph drawings as graph mazes: An eye tracking study

There are various styles to visually represent relational data in the form of node-link diagrams. In particular, for planar graphs we can find orthogonal node-link diagrams consisting of links bending only at ninety degrees a successful and prominent variant. One of the benefits of such drawings is the tracking of longer paths through a network with the eyes due to their limited number of link orientations, changes, and variations, but on the negative side the links can have arbitrary bending shapes. In this article we developed a novel way to visualize such orthogonal planar drawings by making use of mazes that look more natural to the human eye due to the street-like visual metaphor that many people are familiar with. Tracking paths is one of the major tasks in such graph visualizations, similar to orthogonal node-link diagrams, however, we argue that mazes are a more natural way to find paths. To get insights in the visual scanning behavior when reading graph mazes we conducted a comparative eye tracking study with 26 male versus female participants of different experience levels while also alternating between orthogonal node-link drawings and graph mazes as well as different graph size levels. The major result of this comparative study is that the participants can track paths in both representation styles, including a geodesic path tendency in their visual search behavior, but typically have a longer fixation duration at branching nodes and locations in the mazes that lead to opposite directions to the geodesic path tendency, maybe the viewers had to start a reorientation phase in their visual scanning behavior. We also found out that the size, that is the number of graph vertices has an impact on the visual scanning behavior for both orthogonal node-link diagrams as well as street-like maze representations, but for the mazes we found this impact to be less strong (in terms of the eye movement data metrics fixation durations and saccade lengths) compared to the node-link diagrams. To conclude the article, we discuss limitations and scalability issues of our approach. Moreover, we give an outlook and future work for possible extensions.

Strength design of built-up radially battened columns subject to axial compression and arbitrary directional bending moment

Built-up radially battened columns (RBCs), comprising several identical circular steel tubes interconnected by multiple radial-shaped battens, represent an innovative column design that combines aesthetic appeal with exceptional load-bearing capacity. This makes them well-suited for architectural applications in large public buildings such as stations and airports. The axial compressive strength design methods for the built-up RBC have been extensively explored in the authors' prior studies. However, in real-world engineering applications, built-up RBCs may experience simultaneous axial compression and varying directional bending moments, particularly when considering potential eccentric compression or wind and earthquake loads in public buildings. Currently, strength design methods for this loading condition are still lacking. To address this deficiency, this paper primarily delves into the failure mechanism and strength design methods for built-up RBCs experiencing combined axial compression and arbitrary directional bending moments. Initially, the sectional strength of the built-up RBC is investigated by using a shell finite element model (FEM) for the built-up RBC. It is revealed that the compression-bending sectional strength of the built-up RBC exhibits significant differences with varying bending directions and tube numbers. Moreover, in some bending directions, the M-N sectional strength curve of the built-up RBC exhibits convexity. By integrating theoretically derived equations grounded in the principles of materials mechanics with FEM numerical calculations, concise and practical design equations are proposed for accurately predicting the sectional strength of the built-up RBC under combined axial compression and arbitrary directional bending moments. Subsequently, The buckling strength of the built-up RBC is studied using the FEM, considering initial geometrical imperfections consistent with first-order flexural buckling and accounting for geometric nonlinearity. It is noted that the bending direction of the built-up RBC may deviate during loading. Besides, the M-N buckling strength curve of the built-up RBC is not as convex as its M-N sectional strength curve. Based on calculations from numerous examples, practical design equations for predicting the buckling strength for the built-up RBC under axial compression and any directional bending moments are introduced. The key findings of this paper contribute to the compression-bending strength design of RBCs, enriching RBC design theory and promoting the widespread application of built-up RBCs in actual engineering projects.

Laser Printing of Large‐Area Conformal 3D photonic Circuits in Glass

AbstractPhotonic integrated circuits (PICs) are iterating on electronic ones to enable higher‐speed parallel computing while meeting the growing demands for energy efficiency in big‐data processing. However, manufacturing multi‐layered and 3D PICs remains challenging based on conventional planar lithography. Here, a rapid prototyping technique is delineated to configure large‐area and 3D PIC in glass based on laser‐direct written optical waveguides by employing femtosecond cylindrically polarized vortex laser beams. The vortex laser beam is mathematically rotationally invariant and capable of conformally transforming waveguide cross‐sections at arbitrary bending angles of 0–90° and across a large depth change. Based on this approach, a one‐layer 12‐core waveguide circuit with a variable cross‐section (diameter 5–11.5 µm) while maintaining a high mode ellipticity >0.974, as well as a more complex three‐layer 36‐core connector in which the waveguide dives continuously from 50 µm to 550 µm with a small loss difference of <0.1 dB is demonstrated. This work offers a pathway for 3D imprinting of large‐area photonic circuits in glass and other transparent materials, which has potential applications in high‐efficiency photonic computing, multidimensional quantum networks, and 3D optics topology.

Experimental and numerical investigation on out-of-plane ultimate strength of high-strength steel arches

This study presents an experimental investigation on the out-of-plane ultimate strength of high-strength-steel (HSS) I-section arches, which has not been reported previously. Fourteen I-section HSS arches having different yield strengths, cross-sectional dimensions, slendernesses, and rise to span ratios were tested under three-point symmetrical vertical loading. The corresponding out-of-plane deformation modes and strengths are identified. Subsequently, in order to predict the out-of-plane capacities of HSS arches, a finite element analyses is carried out, which takes into consideration residual stresses and initial geometrical imperfections. This analysis demonstrates a strong alignment with the experimental results, confirming the accuracy of finite element model and experimental results. Furthermore, the study comprehensively analyzes the influence of yield strength of steel, rise-span ratio, and slenderness on the ultimate bearing capacity of HSS arches. Through a parametric analysis, design formulas for the out-of-plane bearing capacity of HSS arches subjected to arbitrary compression forces combined with arbitrary bending moments are formulated. It is found that the out-of-plane ultimate strength of HSS arches is significantly influenced by the yield strength of the steel. Compared to a low strength steel (LSS) arch, the out-of-plane ultimate bearing capacity of the HSS arch increases with an increase in yield strength in the plastic stage, and the ultimate lateral displacement of the HSS arch decreases with an increase in yield steel strength due to the lower ductility of HSS. In addition, after reaching the out-of-plane ultimate bearing load of arch, the load-displacement curve of the HSS arch drops faster than the LSS arch. It is also found that the proposed design formulas can effectively predict the out-of-plane bearing capacity of HSS arches.

Automatic extraction of non-bifurcated lunar lineaments from Lunar Reconnaissance Orbiter (LRO) monochromatic images based on a Markov chain method

ABSTRACT Lineaments play a critical role in the study of lunar geological evolution. However, lineaments still need to be extracted manually which constrains lunar research. To fill this gap, a Markov chain-based methodology is introduced for automatically extracting vector-based non-bifurcated lineaments from images. The extracted lineaments are formed by successive nodes and line segments, where nodes denote pixel positions and line segments represented connecting lines between nodes. A modified U-net with residual shortcut connections and dilated convolutions is proposed based on the elongated shapes of lineaments to evaluate the probability of nodes belonging to lineaments. Four connection shape features are proposed to describe the connection shapes of nodes and a Gaussian Mixture Model is used to evaluate the probability of line segments belonging to the lineaments based on the proposed features. In the final stage, the lineament probabilities of both nodes and line segments to extract lineaments are considered in the Markov chain. Our method has experimented on a dataset containing 220 samples and 10-fold cross-validation was used to evaluate the performance. Both qualitative and quantitative results indicated that our method can effectively extract non-bifurcated lunar lineaments with arbitrary bending. The method sheds useful light on automatic lineament extraction.

Analytical frequency-domain solution for Euler-Bernoulli frames with semi-rigid connections

This paper presents a novel method for analyzing the dynamic response of plane Euler-Bernoulli frames with semi-rigid connections subjected to arbitrary external loads and bending moments. The proposed solution methodology is the Green’s Functions Stiffness Method (GFSM) in the frequency domain. The GFSM is a mesh reduction method closely related with the Finite Element Method (FEM) sharing with it key components such as shape functions, fixed end forces, and stiffness matrices. By capitalizing on the strengths of both FEM and Green’s Functions, the GFSM facilitates the derivation of closed-form solutions for structural analysis. The formulation is initially established in the frequency domain and is later transformed into the time domain using the fast Fourier transform algorithm. To illustrate the applicability of the method, an example involving a one-bay, one-storey plane frame with semi-rigid connections is presented.

Convenient self-assembled PDADMAC/PSS/Au@Ag NRs filter paper for swift SERS evaluate of non-systemic pesticides on fruit and vegetable surfaces.

The goal of food safety supervision is to directly identify the pesticide residues on the surface of fruits and vegetables. This study proposed to develop a facile, non-destructive, and sensitive method based on surface-enhanced Raman scattering (SERS) to detect non-systemic pesticides on the surface of fruits and vegetables. The composite material was prepared by loading CTAB guided Au@Ag NRs with positive charge onto filter paper which was modified with PDADMAC(+) and PSS(-) using electrostatic adsorption. Au@Ag NRs with bimetallic synergies were effectively adsorbed in the fiber grid to generate 3D SERS hotspots within a few microns of depth. The results showed that the 3D composite flexible substrate had a high SERS activity, great repeatability, and sensitivity when the method was utilized to detect 4-MBA, methyl-parathion, thiram and chlorpyrifos. Three kinds of non-systemic pesticides on the peel could be detected directly and quickly owing to the arbitrary bending of the substrate, demonstrating the efficiency of the SERS "paste-reading" method. The acquired findings demonstrated that PDADMAC/PSS/Au@Ag NRs composite filter paper had the potential to provide rapid feedback for in-situ analysis of pesticide residues on the surface of fruit and vegetable.

Closed-form solution for non-uniform Euler–Bernoulli beams and frames

Non-uniform elements, such as non-prismatic and those made from composite materials, are commonly used in structures. This is because the variation in their internal forces makes uniform elements less effective to withstand the external loads. This paper presents the formulation of the Green’s Functions Stiffness Method (GFSM) for the static analysis of non-uniform Euler–Bernoulli frames subjected to arbitrary external loads and bending moments. The GFSM is a mesh reduction method that combines the strengths of the Stiffness Method (SM) and the Finite Element Method (FEM) with those of Green’s functions, resulting in an analytic method for obtaining closed-form solutions of reticular structures. As a particular case, the GFSM is closely related to the Transcendental Finite Element Method (TFEM), which allows to obtain closed-form solutions from an implementation of the latter by only making changes at the post-processing stage. Two examples are provided with the analysis of a beam and a plane frame. Additionally, two appendices are included with the particularization of the GFSM for some specific non-uniform elements, and general stepped elements.

Closed-form solution of Timoshenko frames using the Green’s Function Stiffness Method

This paper presents the formulation of the Green’s Function Stiffness Method (GFSM) for the static analysis of Timoshenko frames subjected to arbitrary external loads and bending moments. The GFSM is a novel analytic method that provides closed-form solutions of structures by combining the strengths of the Stiffness Method (SM) (exact relation between forces and displacements at the element ends) and Green’s functions (GF) (analytical closed-form structural response to any arbitrary external load). The GFSM is based on the classical idea of decomposing the solution of differential equations into homogeneous and particular (fixed) solutions, with the latter computed through superposition integrals using Green’s functions of fixed elements as kernels. Its principal aim is the computation of the displacements fields, while the internal forces are calculated directly from their derivatives. The GFSM is directly related to the SM and the Finite Element Method (FEM), making its numerical implementation easily performed from either of them. Additionally, the basic ideas behind the GFSM can be easily extended to other physical fields. An example is presented to show the advantages of the proposed method.

Synergistic Bimetallic CoCu-Codecorated Carbon Nanosheet Arrays as Integrated Bifunctional Cathodes for High-Performance Rechargeable/Flexible Zinc-Air Batteries.

The unremitting exploration of well-architectured and high-efficiency oxygen electrocatalysts is promising to speed up the surface-mediated oxygen reduction/evolution reaction (ORR/OER) kinetics of rechargeable zinc-air batteries (ZABs). Herein, bimetallic CoCu-codecorated carbon nanosheet arrays (CoCu/N-CNS) are proposed as self-supported bifunctional oxygen catalysts. The integrated catalysts are in situ constructed via a simple sacrificial-templated strategy, imparting CoCu/N-CNS with 3D interconnected conductive pathways, abundant mesopores for electrolyte penetration and ion diffusion, as well as Cu-synergized Co-Nx /O reactive sites for improved catalytic activities. By incorporating a moderate amount of Cu into CoCu/N-CNS, the bifunctional activities can be further increased due to synergistic oxygen electrocatalysis. Consequently, the optimized CoCu/N-CNS realizes a low overall overpotential of 0.64V for OER and ORR and leads to high-performance liquid ZABs with high gravimetric energy (879.7Wh kg-1 ), high peak power density (104.3mW cm-2 ), and remarkable cyclic stability upon 400h/1000 cycles at 10mA cm-2 . More impressively, all-solid-state flexible ZABs assembled with the CoCu/N-CNS cathode exhibit superior rate performance and exceptional mechanical flexibility under arbitrary bending conditions. This CoCu/N-CNS monolith holds significant potential in advancing cation-modulated multimetallic electrocatalysts and multifunctional nanocatalysts.

Bending Resistance Covalent Organic Framework Superlattice: “Nano-Hourglass”-Induced Charge Accumulation for Flexible In-Plane Micro-Supercapacitors

HighlightsCovalent organic framework (COF) superlattices were assembled by free-standing COF nanofilms based on the van der Waals force for the first time.Geometry-induced “nano-hourglass” steric configuration in COF superlattice can provide rapid charge transfer/accumulation at heterojunction interface for in-Plane Micro-supercapacitors.The prepared MSC exhibited a high energy density of 63.2 mWh cm−3 even after high-angle and repeat arbitrary bending from 0 to 180°.

Closed-form solution of Timoshenko frames with semi-rigid connections

The response of steel frame structures is highly influenced by the degree of rotational stiffness of the connections between beams and columns, which are characterized by nonlinear moment–rotation (M−θr) curves. Design codes such as the ANSI/AISC 360-16 and the Eurocode 3 specify that the effect of the joints rotational stiffness should be included in the linear and/or nonlinear structural models used in the steel design process. To model the effect of the degree of rigidity between structural elements, it is a common practice to use zero-length semi-rigid connections. This paper presents the static formulation of the Green’s Functions Stiffness Method (GFSM) for prismatic Timoshenko frames with zero-length elastic semi-rigid connections subjected to arbitrary external loads and bending moments. The GFSM is a novel analytical method based on the classical Stiffness Method (SM), and the Green’s Functions (GFs), for the computation of closed-form solutions of the response of structures. This method is formulated from the decomposition of the structural response into two complementary parts: a homogeneous response (related to the stiffness matrix and the shape functions) and a particular or fixed response (associated with the load vector and the fixed displacement field), the latter computed using GFs of fixed elements. An example of a one-bay one-storey two-dimensional frame is presented.

Enhancement of mechanical property and formability of CFRP core sandwich sheets by additive manufacturing process-induced material and structural anisotropies

The additive manufacturing (AM) of fiber reinforced plastics has gained much interests in the design of lightweight structures with superior mechanical performance. Strong anisotropy can be induced during the extrusion process owing to the preferentially orientated fiber reinforced plastics with high aspect ratio. To make better use of AM-induced material anisotropy, an integrated material-structure-performance design strategy for AM-produced carbon fiber reinforced plastic (CFRP) structures was proposed, in which the microscopic material and mesoscopic structural anisotropies were integrated to achieve enhanced macroscopic mechanical performance of CFRP core structures and sandwich sheets. The effects of AM process parameters including the layer thickness and build orientation on microscopic material anisotropy of the AM produced CFRP were firstly investigated and the strong relationship between material anisotropy and AM process parameters was confirmed by extensive mechanical tests and microscopic observations. A new core structure possessing the arbitrary bending anisotropy was proposed and the relationship between structural anisotropy ratio and bending stiffness was clarified. In addition, the mechanical properties of core structures were tested and superior mechanical performance can be achieved by tailoring the combination of material and structural anisotropies. The effects of structural anisotropies on mechanical properties and face buckling behaviors of sandwich sheets were investigated and found that face buckling is the dominant failure behavior. The new finding that the integration of microscopic material anisotropy and mesoscopic structural anisotropy induced by AM could enhance the mechanical property and formability of CFRP core sandwich sheets is of great significance in the design of lightweight structures. • An integrated material-structure-performance design strategy for additive manufacturing (AM) produced fiber reinforced plastic structures • The effects of AM process parameters including layer thickness and build orientation on microscopic material anisotropy of CFRP are clarified • Structure that can achieve an arbitrary bending anisotropy is proposed • The relationship between structural anisotropy ratio and bending stiffness is investigated • Better mechanical performance can be achieved by the integration of material and structural anisotropies

A Ring-Shaped Curved Deformable Self-Powered Vibration Sensor Applied in Drilling Conditions

Because of their low flexibility, traditional vibration sensors cannot perform arbitrary bending adjustments when facing curved surfaces and other complex working conditions during the drilling process; therefore, this research proposes a ring-shaped vibration sensor (RSV−TENG) that can deform freely in the bending direction, and which can be used in working conditions where the inner bending angle of the drill pipe changes greatly. Test results show that the vibration frequency measurement range is from 4 Hz to 16 Hz, with a measurement error less than 4%, the vibration amplitude measurement range is less than 20 mm, with a measurement error less than 5%, the output voltage and current signal are 120 V and 60 nA, respectively, when three RSV−TENGs are connected in parallel, and the maximum output power is 6 × 10−7 W when the external resistance is 106 Ω. Compared with traditional downhole sensors, this sensor has self-powered and self-sensing functions, eliminating the shortcomings of battery and cable power supply; in addition, this sensor can be installed in the drill pipe space with different curvature radii, so it is more suited to complex and changeable downhole working conditions.

Bending of optical solitonic beams modeled by coupled KMN equation

The dynamics of (2 + 1) dimensional optical solitonic beams modeled by coupled Kundu Mukherjee Naskar (KMN) equation are discussed by deriving one bright and one dark soliton solution. The arbitrary bending of solitonic beams of this coupled system has been described by exact curved soliton solutions having an arbitrary function. Such exact analytical results on the bending of solitonic pulse in a bimodal optical fiber system may pave new research directions in this field.

Biofilm based hygroelectric generator: Research on flexibility and self-healing characteristics

<p indent="0mm">As an emerging energy technology, hygroelectric generators can use the energy of environmental moisture to generate electricity. They have attracted considerable attention from researchers in the field of green energy. We prepared a biofilm-based hygroelectric generator on an ITO-conductive glass substrate based on the whole-cell <italic>Geobacter sulfurreducens</italic> (<italic>Gs</italic>) in the early stage (<italic>b</italic>-HEG), which exhibits excellent power-generation performance. However, the monotonous, rigid structure severely limits its application under complex working conditions. In this study, a <italic>b</italic>-HEG with a fast self-healing function and high flexibility was successfully prepared based on the <italic>Gs</italic> film and flexible substrate PET–ITO. The generator <sc>(1 cm²)</sc> can generate <sc>0.65 V</sc> of open-circuit voltage, 6.4 μA of short circuit current, <sc>1.087 μW/cm²</sc> of output power density, and continuously generate power for <sc>&gt;48 h</sc> without attenuation.<italic> </italic>The <italic>b</italic>-HEG has the characteristics of arbitrary folding and bending and rapid self-healing. It can recover 100% of its flexibility and power-generation capacity within <sc>1.5 min</sc> after the loss of power-generation function by cutting off the biofilm. Additionally, it can be self-healed in multiple cycles to avoid the failure of the device due to deformation or fracture damage in the future working process. Further, it can realize the sustainable power-generation function of the device in a complex working environment. At the same time, the generator has a simple manufacturing process, low cost, zero pollution, and zero carbon emissions, which is of great significance for the development of global carbon neutrality and green energy technologies.

Statistical life prediction of a unidirectional carbon fiber/polypropylene laminates under creep bending load

Our developed accelerated testing methodology (ATM) based on matrix resin viscoelasticity for the long-term life prediction of carbon fiber reinforced plastics (CFRP) was applied to assess the statistical prediction of long-term creep failure time of a carbon fiber/polypropylene unidirectional (CF/PP) laminates under creep bending load. Results show that the statistical long-term creep failure times under an arbitrary constant bending load and temperature for the CF/PP laminates can be easily predicted from the statistical static strengths of the CF/PP laminates measured at several temperatures and the viscoelasticity of matrix PP.