Bent Path Research Articles

A novel polysulfone ultrafiltration membrane constructed with the sandwich-like structure SGO-ZnO for ultra-easy water transport and enhanced anti-fouling

Fouling formation on membrane surfaces limits membrane-based separation performance in industrial activities such as wastewater recycling and desalination. Designing and preparing emerging materials capable of improving the balance between permeability and rejection remains a great challenge. A sandwich-like composite with loose and flat interlayers was produced by combining rigid zinc oxide (ZnO) nanoparticles with easily stackable, folded sulfonated graphene (SGO) and subsequently non-solvent-induced phase separation (NIPs) was employed to produce novel PSF ultrafiltration (UF) membranes with varying amounts of nanofiller of SGO-ZnO. The successful anchoring of ZnO on SGO was confirmed by FTIR, XRD, Raman spectroscopy and TGA. The produced membranes have been investigated using contact angle (CA), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The incorporation of ZnO suppressed the stacking and wrinkling of SGO, which increased the vertical interlayer paths and lateral bending paths. As a result, water molecules could freely pass through the extended channels of SGO, and with only 0.2 wt% of nanoparticles doped, the pure water flux was increased f from 229.2 L m−2h−1 to 601 L m−2h−1. Negatively charged impurities were selectively repelled due to electrostatic interactions with −SO3H, which resulted in the removal of BSA remaining above 98 %. In addition, the separation performance of the humic acid (HA)-simulated water sample, a common contaminant, was investigated using the designed modified membranes. The greatest HA rejection (98.33 %) was shown by the UF membrane. All these findings suggest that the addition of sandwich-like SGO-ZnO successfully overcomes the “trade-off effect” between permeability and selectivity in PSF membranes.

48‐2: Research on Mechanical Simulation of Flexible AMOLED Module Bottom Frame

With the development of science and technology and consumers' pursuit of high screen ratio, the frame of terminal flagship products has become an important research direction. However, the thinner the bottom frame is, the higher probability of metal wire breakage in bending area. In this paper, we use finite element analysis to simulate the whole bending process of bottom frame, study the influence of bending path, indenter displacement, bending radius and buffer zone on metal wire, summarize the failure mechanism, which provides theoretical basis for fault analysis, stacking structure design and smaller radius design.

Nonlinear Terminal-Free MPC on Multitype Bend Tracking With Discontinuous Reference Paths for Autonomous Vehicles

In this paper, multitype bend tracking with discontinuous reference paths is researched by a nonlinear terminal-free model predictive control (MPC) with an artificial reference path for an autonomous vehicle. The MPC strategy without terminal penalty and terminal state constraints is proposed to deal with the discontinuous reference paths, which improves solvability on an optimization problem effectively. The artificial reference path is designed to realize replanning and smoothing for multitype bend paths. Both recursive feasibility and stability are discussed for the autonomous vehicle by a lower bound of prediction horizon and a controlled forward invariance set. Effectiveness of the nonlinear terminal-free MPC strategy is shown by experimental results on multitype bend path for the autonomous vehicle.

B0-VPG Representation of AT-free Outerplanar Graphs

A $k$-bend path is a non-self-intersecting polyline in the plane made of at most $k+1$ axis-parallel line segments. B$_{k}$-VPG is the class of graphs which can be represented as intersection graphs of $k$-bend paths in the same plane. In this paper, we show that all AT-free outerplanar graphs are B$_{0}$-VPG, i.e., intersection graphs of horizontal and vertical line segments in the plane. Our proofs are constructive and give a polynomial time B$_{0}$-VPG drawing algorithm for the class. In fact, we show the existence of a B$_{0}$-VPG representation for a superclass of AT-free graphs namely linear outerplanar graphs which we define as the class of subgraphs of biconnected outerpaths. Outerpaths are outerplanar graphs which admit a planar drawing whose weak dual is a path. Following a long line of improvements, Gonçalves, Isenmann, and Pennarun [SODA 2018] showed that all planar graphs are B$_{1}$-VPG. Since there are planar graphs which are not B$_{0}$-VPG, characterizing B$_{0}$-VPG graphs among planar graphs becomes interesting. Chaplick et al. [WG 2012] had shown that it is NP-complete to recognize B$_{k}$-VPG graphs within B$_{k+1}$-VPG. Hence recognizing B$_{0}$-VPG graphs within B$_{1}$-VPG is NP-complete in general, but the question is open when restricted to planar graphs. There are outerplanar graphs and AT-free planar graphs which are not B$_{0}$-VPG. This piqued our interest in AT-free outerplanar graphs.

Arbitrary temperature gradient in thermal-postbuckling behavior of polymer nanocomposites reinforced by boron nitride nanotubes

Polymer nanocomposites reinforced by boron nitride nanotubes (BNNTs) have great potential for use in a wide variety of thermal environments. A closed-form solution for nonlinear bending and thermal-postbuckling behavior of BNNT-reinforced nanocomposite beams under arbitrary temperature gradient in the thickness and length directions is presented for the first time. The uniform and functionally graded (FG) distributions of BNNTs through the thickness of macro-or micro-sized beams are considered. For constant temperature or constant heat flux conditions at two ends of the beam, thermal analysis is carried out to obtain temperature field ΔTx,z using the two-dimensional heat conduction equation and the assumption of arbitrary variation in the z direction. The governing equations of modified couple stress Timoshenko beam theory with von Kármán geometric nonlinearity are derived for BNNT-RC beams subjected to thermomechanical loads. Applying change of variable technique, the governing equations are exactly solved to develop closed-form expression for nonlinear transverse deflection. Finally, parametric study is performed to investigate the effects of length scale parameter, aspect ratio (L/h), distribution of BNNTs, and temperature gradient on the nonlinear bending and postbuckling equilibrium paths. It is shown that the thermal-buckling behavior of clamped and cantilever beams is completely different. Under thermomechanical loading, an initial snap-through buckling behavior is observed in the cantilever beam, while there exist both stable and unstable configurations in the static equilibrium path of clamped beam. Moreover, it is found that the assumption of parabolic variation of temperature through thickness is not compatible with real situations, since the temperature field is obtained as harmonic functions with very short wavelengths in the length direction.

Selective element domain interpolation technique for assumed rotations and shear strains in polygonal finite element thick/thin plate analysis

This paper proposes a novel selective element domain interpolation technique, named SI-ARS-Poly, to develop a high-performance spatially isotropic polygonal element for thick/thin plate analysis. In the SI-ARS-Poly approach, nodal assumed rotations on the element boundaries are directly computed at the mid-nodes of element edges by linearly approximating based on the first-order one-dimensional shape functions. Then, a selective interpolation scheme is applied to approximate the nodal assumed rotations and shear strains on element boundaries into the element domain using piecewise-linear-based first- and second-order shape functions. The proposed method passes spatially isotropic, zero-energy mode, and bending path tests, and exhibits a high performance with uniform and excellent convergent rates compared to existing methods.

Design of a Flexible Weight Sensor Using Optical Fibre Macrobending

A flexible weight sensor based on optical fibre macrobending loss, using 1550 nm wavelength light and small fibre bending path lengths is presented. An applied load depresses an impactor layer of cylindrical protrusions into a soft mat covered with optical fibre, causing the optical loss of the fibre to increase. An experimental study of two fibre types, two impactor materials, two impactor designs and a range of protrusion bend radii from 3 mm to 10 mm is shown. For weights greater than 2 kg, a linear response in optical loss (dB) is observed for an applied weight load in kg. The proportionality constant between loss and load, and thus the total amount of optical loss for up to 10 kg of weight load, can be tuned by changing the sensor physical parameters, shown here in ranges from 0.5 dB up to 25 dB.

Design of multi-stimuli responsive hybrid pneumatic – magnetic soft actuator with novel channel integration

Smart polymeric materials based soft actuators are flexible, lightweight, and can deliver a wide range of actuations. Thus, they are ideal for applications requiring delicate and unconventional motions, such as biomedical and soft robotics. This paper reports a novel multi-stimulus responsive soft actuator that combines the advantages of pneumatic and magnetic systems to achieve multi-plane actuation behavior with high blocking forces at low power input. This novel pneumatic – magnetic (HPM) soft actuator is designed through geometric, nanoparticle alignment, and mechanical criterions. By utilizing 3D printed wires and the compliant matrix, unique micro air channels were manufactured. These distinct internal tubular structures created localized and distinctive bending paths beyond the traditional circular trajectory. Addition of Fe3O4 nanoparticles under a magnetic field exhibited a decrease in stiffness of the elastomer matrix by 85%, increasing the blocking force by 3500%, and decreasing the air pressure input to achieve same degree of actuation. Furthermore, it was observed that the magnetic nanoparticles alignment within the samples enhanced the magnetic deflection and susceptibility. The HPM soft actuator demonstrated its practicability through a gripper system to lift objects greater than its initial width and 3.4 times its own mass. Multi-plane actuation was also demonstrated to complete a circuit and light up an LED. A 5 legged “star” shaped HPM soft actuator was also fabricated to exhibit the multi-stimuli response, reacting to both pneumatic and magnetic stimuli in both air and water environments. Using the advantage of the multi-plane pneumatic/magnetic actuation, such hybrid soft actuator has the capability to be utilized in biomimicking and unconventional applications where unique maneuverability is required.

Alpha (α) assumed rotations and shear strains for spatially isotropic polygonal Reissner-Mindlin plate elements (αARS-Poly)

This paper proposes simple and efficient alpha assumed rotations and shear strains for polygonal plate elements, named αARS-Poly. In the αARS approach, an alternative assumption of the tangent rotations along element boundaries is applied by using the approximation of the rotations in Timoshenko's beam theory. Then, the quadratic term of this assumed field is linearly scaled up by adding an artificial positive scaling factor α>0. Through examination of the relative errors in the energy (s-) norm regarding α in numerical experiences, the value α=0.5 can be chosen as a general-fixed value that possibly achieves the optimal relative errors of the s-norm. The value α=0.5 seems to be not only mesh-independent but also problem-independent. The αARS-Poly element using α=0.5 passes all critical tests (spatially isotropic, zero-energy mode, and bending path tests) for a finite plate element which ensures the element orientation-independent property, solution stability, and free shear-locking in the thin plate limit. The implementation of the αARS-Poly element is straightforward through a unified form of the stiffness matrix for all arbitrary convex-shaped polygonal meshes. Numerical results show that the proposed element achieves high reliable and optimal results with uniform and excellent convergent rates in the static and free vibration analyses.

Fiber Bragg Grating-Based Smart Garment for Monitoring Human Body Temperature.

Body temperature provides an insight into the physiological state of a person, and body temperature changes reflect much information about human health. In this study, a garment for monitoring human body temperature based on fiber Bragg grating (FBG) sensors is reported. The FBG sensor was encapsulated with a PMMA tube and calibrated in the thermostatic water bath. The results showed that FBG sensors had good vibration resistance, and the wavelength changed about 0–1 pm at a 0.5–80 Hz vibration frequency. The bending path of the optical fiber after integration with clothing is discussed. When the bending radius is equal to or greater than 20 mm, a lower bending loss can be achieved even under the bending and stretching of the human body. The FBG sensor, the optical fiber, and the garment were integrated together using hot melt glue by the electric iron and the hot press machine. Through experiments of monitoring human body temperature, the sensor can reach the human armpit temperature in about 10–15 min with the upper arm close to the torso. Because it is immune to electromagnetic interferences, the smart garment can be used in some special environments such as ultrasonography, magnetic resonance (MR), and aerospace.

P‐4.4: Path Planning Analysis of Pad Bending Process for the Full Screen OLED Panel

In the pad‐bending process of the full‐screen panel, the metal wire in the bending area is easily broken due to deformation, and the occurrence of the break is related to the bending path. This paper analyzes the influence of different bending paths on the peak stress of the metal wire, determines the method to explore the reasonable path based on mathematical theory, and provides guidance for the pad‐bending process design, which can be used to improve the yield of pad‐bending process of OLED panels.

Multidisciplinary optimization of the waveguide transmission line for ITER HFS reflectometry

The research is devoted to the application of parametric optimization methods to the design of the waveguide line of ITER High Field Side Reflectometry (HFSR) diagnostic system. This waveguide line in the Interspace and Port Cell zones, on the one hand, must provide enough flexibility of the structure to withstand interface mechanical loads, and on the other hand, must ensure low signal losses. In order to satisfy these two contradicting requirements, an optimization problem was formulated and solved. Two different parametric optimization algorithms were used in conjunction with MATLAB and ANSYS software to find a reasonable design of the HFSR waveguide. MATLAB was used to construct the bend path with the minimal signal losses, and ANSYS was used to calculate the mechanical response of the constructed waveguide to the applied loads.

Axial formation and cross-section distortion control for stretch bending based on batch simulations

Stretch bending is a widely used to form long parts with a definite cross-section shape. The forming path is an effective way to eliminate the defects such as springback, distortion when the material and the die shape are determined. In this study, the stretch bending path is represented by a curve function of bending angle and stretch length. To simplify the path optimization problem, the path is represented by 4 parameters, including a newly introduced parameter of total stretch. Based on the batch simulation results, it is found that the axial springback and cross section distortion are primarily controlled by total stretch, bending angle and pre-stretch proportion. When the total stretch is determined, the different distribution schemes for pre-stretch, bending stretch and post-stretch in total stretch have a similar effect on forming quality except the schemes with extremely large proportions of pre-stretch. In most cases, with the total stretch length in growth, the axial springback decreases dramatically at first and then stays constant while the section distortion continues to rise, indicating that the optimal forming path is around the elbow point in the relationship curve of total stretch and springback angle. The optimal path is verified by experiments. It is shown that for a workpiece with determined material and die shape, the optimal path to minimize axial rebound and section distortion simultaneously does exit and the study provide an effective way to obtain it.

An Effective Sharp Curve Lane Detector

Sharp bend path location is one of the difficulties of visual condition discernment innovation for self-governing driving. Right now, new hyperbola fitting based technique for bend path recognition is proposed. The strategy for the most part incorporates three sections: extraction, bunching, and hyperbola fitting of path highlight focuses. We analysed our technique with the Bezier bend fitting based, the least squares bend fitting based, the spline fitting based techniques, and a current hyperbola fitting based strategy. Examinations show that our strategy performs superior to these technique.

Design, material properties and performances of a smart hinge based on shape memory polymer composites

Shape memory polymer composites (SMPCs) are gradually applied to deployable space structures due to their special shape memory effect and excellent mechanical properties. The design, material properties and performances of a smart hinge based on SMPC were investigated in this paper. The micro-buckling problem of the inner sheet of the hinge was solved by designing the bending path. The mechanical properties of materials with different fiber layers were characterized. The performance investigations began with obtaining the optimal voltage, followed by the test of the recovery speed, heat distribution and digital image correlation (DIC) for the SMPC hinge. The recovery force and deployed stiffness of the hinges with the different fiber layers followed by the observation of the variation of the surface morphology were obtained. The results indicated that the 3-layer hinge performed better than the 2-layer and 4-layer hinges in terms of deployed stiffness and surface morphology. Additionally, the strain variation of the hinge sheets was obtained. Finally, the smart hinge was assembled into the solar array prototype and the ground deployment verification test was successfully carried out. The research results of the hinge are expected to have reference significance in deployable space structures.

Developing an adaptable pipe inspection robot using shape memory alloy actuators

To detect and repair the faults existing in pipes and narrow ducts in the industry, access to the inside of these pipes is often required. In this article, the conceptual design for a miniature robot for inspecting the inner walls of pipes is presented, such that the proposed robot can operate adaptably and freely in vertical, inclined, and bent paths. The robot utilizes a simple mechanism based on shape memory alloy actuators for adjusting the contact force between the robot and the inner wall of the pipe. Use of shape memory alloys as actuators for the adaptive part will result in a smaller and lighter robot, further increasing its mobility in narrower ducts. Modeling, simulation, and control of the proposed system is conducted and simulation results are validated by performing practical laboratory experiments on a built prototype.

Residual stresses and strains analysis in press-braking bending parts considering multi-step forming effect

Press-braking bending is a multi-step bending process and widely applied in the aerospace industry. Residual stresses and strains generated during the forming process play an important role in determining its forming parameters and bending path. This work aims to analyze the residual stresses and strains in press-braking bending parts using both the theoretical method and numerical method. First, the analytical model of residual stress and strain is established based on the elastic–plastic bending theory. Second, a fully finite element model of press-braking bending has been developed, and a procedure to simulate the multi-step bending process is presented by using the elastic–plastic large deformation finite element method. The simulation results are then compared with three-point bending experiments in terms of forming force and final shapes of the bent specimens, and excellent agreement is achieved. Finally, the results calculated from the analytical model are compared with the numerical results. The distributions of residual stresses and strains on the finished plate along the length and thickness direction, and particularly the multi-step forming effect on residual stresses and strains, are discussed. It is found that the residual stresses and strains decrease at the initial loading position along the thickness direction during the forming process of subsequent loading positions. With the same punch displacement, the residual stresses and strains at the initial loading position are less than those at the subsequent bending position.

Gas Sensor by Direct Growth and Functionalization of Metal Oxide/Metal Sulfide Core-Shell Nanowires on Flexible Substrates.

We have developed a novel fabrication method for flexible gas sensors for toxic gases based on sequential wet chemical reaction. In specific, zinc oxide (ZnO) nanowires were locally synthesized and directly integrated on a flexible polymer substrate using localized hydrothermal synthesis methods and their surfaces were selectively functionalized with palladium (Pd) nanoparticles using a liquid phase deposition process. Because the entire process is conducted at a low temperature in a mild precursor solution, it can be applied for flexible substrates. Furthermore, the surface of ZnO nanowires was sulfurized by hydrogen sulfide (H2S) gas to form zinc oxide/zinc sulfide (ZnO/ZnS) core-shell nanowires for stable sensing of H2S gas. The locally synthesized ZnO/ZnS core-shell nanowires enable an ultracompact-sized device, and Pd nanoparticles improve the sensing performance and reduce the operating temperature (200 °C). The device shows a high sensitivity [(Ggas - Gair)/Gair × 100% = 4491% to 10 ppm], fast response (response/recovery time <100 s) to hydrogen sulfide, and outstanding selectivity (>100 times) to other toxic gases (e.g., carbon monoxide, acetone, ethanol, and toluene). Moreover, vertically synthesized nanowires provide a long bending path, which reduces the mechanical stresses on the structure. The devices showed stable gas sensing performance under 9 mm positive radius of curvature and 5 mm negative radius of curvature. The mechanical robustness of the device was also verified by numerical simulations which showed dramatic decrease of maximum stress and strain to 4.2 and 5.0%, respectively.

Time series data intelligent clustering algorithm for landslide displacement prediction

The traditional time series data clustering for landslide displacement prediction is based on Euclidean distance measure. The time series data is clustered by distance calculation of two vectors. The correlation between components is not considered. The multiple components with single feature will interfere with the clustering results, and the accuracy of clustering results is greatly reduced. To address this problem, an intelligent clustering algorithm for time series data in landslide displacement prediction based on nonlinear dynamic time bending is proposed in this paper. By reconstructing the phase space of the landslide displacement time series, the phase space transposed matrix is obtained as the time series reconstruction matrix. After embedding dimension processing, the time series of landslide displacement is predicted by SVM data mining model. Dynamic time warping calculation is based on the correlation of time series sequence and the components. The local optimal solution is obtained by recursive search, and the whole curve path is obtained. Clustering calculation of time series data set is carried out by using hierarchical clustering algorithm according to bending path. The intelligent clustering results of time series data in landslide displacement prediction is obtained. Experimental results show that the proposed algorithm has better clustering effect and higher clustering accuracy.

Non-crossing Rectilinear Shortest Minimum Bend Paths in the Presence of Rectilinear Obstacles

The paper presents a new algorithm to determine the shortest, non-crossing, rectilinear paths in a twodimensional grid graph. The shortest paths are determined in a manner ensuring that they do not cross each other and bypass any obstacles present. Such shortest paths are applied in robotic chip design, suburban railway track layouts, routing traffic in wireless sensor networks, printed circuit board design routing, etc. When more than one equal length noncrossing path is present between the source and the destination, the proposed algorithm selects the path which has the least number of corners (bends) along the path. This feature makes the path more suitable for moving objects, such as unmanned vehicles. In the author’s scheme presented herein, the grid points are the vertices of the graph and the lines joining the grid points are the edges of the graph. The obstacles are represented by their boundary grid points. Once the graph is ready, an adjacency matrix is generated and the Floyd-Warshall all-pairs shortest path algorithm is used iteratively to identify the non-crossing shortest paths. To get the minimum number of bends in a path, we make a modification to the Floyd-Warshall algorithm, which is constitutes the main contribution of the author presented herein.