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

Pressure vessels are widely used in various aerospace and automotive applications. For some applications with limited space, spherical and ellipsoidal shapes are less attractive than toroids. Toroidal shapes can be defined as curved, endless hollow shapes that eliminate the need for end caps when used for pressure vessels. This study presents an analytical formulation using lamination parameters for the novel design of toroidal pressure vessels. The proposed design is based on stiffness tailoring by changing the fiber tow trajectories spatially through the structure to suppress the direct stress and strain gradients in the thickness direction, leading to reduced structural weight, defined as bend-free variable-angle-tow (VAT) toroidal pressure vessels. For a toroidal pressure vessel with a fixed geometry, the VAT distribution through the structure to suppress bending is obtained. Subsequently, the bending stresses and strain levels in the designed VAT toroidal pressure vessels are assessed numerically and compared with those of their isotropic and constant-stiffness composite counterparts. Results show that the designed VAT toroidal pressure vessel generates considerably lower degrees of bending than its corresponding isotropic and constant-stiffness composite counterparts. [ABSTRACT FROM AUTHOR]

Ethylene-tetra-fluoroethylene (ETFE) is a polymer employed in tension membrane structures with mechanical properties that strongly depend on time and temperature effects. A comprehensive understanding of the mutual influence of these variables and a unified viscoelastic constitutive model design can enable wider exploitation of ETFE in sustainable lightweight construction. This study presents a thermomechanical characterisation of ETFE foils through quasi-static tensile experiments spanning two orders of magnitude of strain rates, creep, relaxation, shear and dynamic cyclic tests in a wide range of temperatures suitable for building applications, from − 20 ∘ C to 60 ∘ C . The experimental results in different material orientations are used to identify the limits of the linear viscoelastic domain, define the direction-dependent creep compliance master curves and calibrate the parameters of a plane stress orthotropic linear viscoelastic model, employing the Boltzmann superposition and the time-temperature superposition principles. The model has been numerically implemented using a recursive integration algorithm and its code is provided open source. A validation on independently acquired data shows the accuracy of the constitutive model in predicting ETFE behaviour within the linear viscoelastic regime usually adopted during structural design, with excellent extrapolation capabilities outside the range of the calibration data. [ABSTRACT FROM AUTHOR]

Aspects of the technical verification of membrane structures Membrane structures represent a unique type of construction that significantly differs from conventional materials such as steel. The filigree, light and flexible membrane materials, which can only be subjected to tensile stress, lead to an organically appearing shape. In contrast to the design with established materials, the shapes of the membrane structures are not freely designable, but the result of a mechanical form‐finding process. These characteristics of membrane structures pose special challenges to all those involved in construction: from the client, the architect and structural engineer, to the fabricators, the construction workers, and especially the design review engineers. The current contribution focuses on aspects of the technical verification of membrane structures, which differ from constructions made of conventional materials. It provides an overview of the specifications of this construction method and their consideration in the verification and gives insight into the necessary structural documents for the verification. Due to the complexity and the specific requirements associated with the technical verification of membrane structures, examples will be used to provide clarity and understanding. [ABSTRACT FROM AUTHOR]

Assembly influences on the long‐term load‐bearing capacity of glass/PTFE fabrics Membrane structures are designed for a service life of between 20 and 25 years. In Germany, a combined ZiE/vBG is required for every membrane structure – whether small or large – which is based on strength and stiffness parameters that are determined on the new material depending on each individual batch. Hereby, strength‐reducing influences are certainly taken into account via reduction factors, but effects from assembly are not sufficiently covered. Glass/PTFE fabrics in particular are sensitive to installation influences such as handling during transport, handling and temperature during the laying of the fabric and weathering, so that long‐term damages in form of cracks in glass/PTFE membrane structures might occur, which (can) result in premature replacement of the entire covering. Investigations into the influence of weathering in combination with handling/installation‐related creases in glass/PTFE fabrics have shown that certain types of creases in glass/PTFE fabrics must be avoided, while others do not (necessarily) have a detrimental effect on the long‐term load‐bearing capacity of the fabric itself. This contribution provides an overview of the current state of knowledge on the influence of weathering and creases on the long‐term load‐bearing capacity of glass/PTFE fabrics as well as recommendations for the correct installation of such membrane structures in order to avoid long‐term damages. [ABSTRACT FROM AUTHOR]

Conserved through modernisation, membrane roofs refreshed Many membrane projects were realised in Europe in the 1990s. After more than 30 years of use in some cases, many of these structures are now due for roof renewal. The aim is to continue using them on a long‐term basis, restore their original attractive appearance and preserve their stability for many years to follow. The examples presented show different reasons for renovation, but also different approaches to their modernisation. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of the diverse approaches employed to study dynamic responses of gossamer membrane structures for space applications. The primary aim of the current review article is to explore the proposals/attempts made in the literature to understand the vibration, wrinkling, and shape control phenomena of these structures using analytical, experimental, and numerical approaches. This review delves into understanding the impact of various parameters/factors such as membrane thickness, aspect ratio, geometric and material properties, aspect ratio, types of load, load ratio, boundary conditions, air added mass, inflation pressure, type of actuators, and their placements etc. on the behavior of membrane structures. [ABSTRACT FROM AUTHOR]

As the number of small satellites in low-Earth orbit increases, the goal of shortening the deorbit period after the end of operation has been set. Along with this trend, a more effective deorbit system than used to date is required. This paper proposes a deorbit component that combines a method of obtaining plasma drag by interference between on-orbit plasma and an electromagnetic field generated by an electromagnetic coil in a small satellite, and a method of obtaining air drag using deployable membranes. The proposed component uses a deployable membrane structure with electromagnetic coils, and it is possible to mount multiple components on a small satellite. It is possible to obtain greater drag using multiple components. In this paper, the plasma drag is calculated using the two-dimensional Full-Particle-In-Cell method when multiple deorbit components are mounted, and the appropriate coil arrangement is clarified. Furthermore, the deorbit duration is calculated by the total drag of the plasma drag and the air drag, and the performance of the proposed deorbit component is evaluated. [ABSTRACT FROM AUTHOR]

Composite membranes with asymmetric traits have gained attention in liquid separation, featuring gradient chemical and physical attributes that align or oppose mass transfer direction. Chemically asymmetric configurations harness internal driving forces to heighten separation efficiency, rendering them an appealing option for heightened separation efficiency and fouling prevention. Concurrently, the internal hierarchical structure differences within composite membranes—such as fiber‐based structural adjustments and the gradient density of functional layers—yield the dual benefits of effective liquid repelling and heightened transport efficiency. Unlike conventional phase‐change methods, electrospinning technology possesses advantages in constructing and governing composite fibrous membrane materials with asymmetric chemistry and hierarchical structures, driven by its adaptable stacking methodologies. Notably, the inherent pore structure of electrospun nanofibrous membranes emerges as a proven solution for minimizing transport resistance. In recent times, interest has surged in electrospun nanofibrous membranes endowed with internal asymmetric properties. However, the spotlight has predominantly graced Janus membranes, spotlighting opposite wettability on different sides, leaving other facets of asymmetric membrane enhancement somewhat underexplored. This comprehensive work unveils recent strides in design, fabrication, facilitated transport mechanisms, and real‐world liquid separation applications, all under the aegis of electrospun nanofiber membranes, each endowed with distinct asymmetric properties. [ABSTRACT FROM AUTHOR]

This paper presents the development of membrane structures in China. It begins with a historical review of the early applications of membrane structures in the country, highlighting pivotal events and engineering endeavors that contributed to the development. Subsequently, recent advancements in the realm of membrane structures in China are succinctly summarized. The past decade has witnessed notable progress in the implementation of membrane structures, particularly within expansive stadiums and indoor sports arenas. Additionally, cases exemplifying the diverse applications of membrane structures in various projects are presented. Noteworthy among these are the incorporation of membrane structures in building facades, suspended ceilings for indoor spaces, and the utilization of ETFT membrane structures. Furthermore, applications of air-supported membrane structures are explored, especially in the areas of sports facilities and environmental protections. Technical standards and specifications that have played an important guiding role in the development of membrane structures in China are introduced in the last. Finally, 8 issues for the future research and development of membrane structures are pointed out in the conclusion part. It is expected that this paper can serve as a catalyst for further advancement and practical implementation of membrane structures in China. [ABSTRACT FROM AUTHOR]

Origami-based membrane structures have shown great potential to revolutionize the construction of deployable and lightweight space structures in the future. However, the efficient unfolding mechanism puts forward major challenges to the practical realization of space-deployable structures. Here, a smart grid-reinforced membrane origami (SGRMO) is presented. The unfolding action hinges upon the application of forces facilitated by shape memory polymer composites (SMPCs). Subsequent locking action ensues through the restoration of the initial rigidity, accomplished via cooling mechanisms. This novel structure achieves the required lightweight and functionality by employing the grid design concept and effectively reduces the decline in unfolding extent caused by irreversible plastic deformation at the crease. Its recovery properties, including unfolding angle, distance, and surface precision, are experimentally and analytically investigated under different conditions. The results indicate that the structure can be reliably unfolded into the predefined shapes. In the case of Miura-SGRMO, the optimal surface precision is attained when the angle-ψ registers at 30°. The results of this study are expected to serve as the design of ultra-large flexible solar arrays and deployable antenna structures. [ABSTRACT FROM AUTHOR]

This article presents a new binocular vision method for accurate deformation measurements of flexible membrane structures. Using enhanced marker points on the membrane, the method identifies areas for displacement measurements, filtering out unwanted image features with scale-invariant feature transform and threshold correlation. It integrates Canny edge recognition and quadratic weighted averaging for precise positioning of measurement points. By comparing reference images and utilizing the principle of minimum distance between matching points, the method achieves fast matching and determines the three-dimensional coordinates of marker points, enhancing measurement efficiency and robustness. This approach has been empirically tested on membrane structures, providing new insights. The results highlight that our novel algorithm can achieve high-precision measurements down to millimeters, and its accuracy increases with the actual displacement of the membrane structure. Notably, this groundbreaking measurement method remains unaffected by the form of the membrane surface, addressing a long-standing challenge in the field.

Origami-based membrane structures have shown great potential to revolutionize the construction of deployable and lightweight space structures in the future. However, the efficient unfolding mechanism puts forward major challenges to the practical realization of space-deployable structures. Here, a smart grid-reinforced membrane origami (SGRMO) is presented. The unfolding action hinges upon the application of forces facilitated by shape memory polymer composites (SMPCs). Subsequent locking action ensues through the restoration of the initial rigidity, accomplished via cooling mechanisms. This novel structure achieves the required lightweight and functionality by employing the grid design concept and effectively reduces the decline in unfolding extent caused by irreversible plastic deformation at the crease. Its recovery properties, including unfolding angle, distance, and surface precision, are experimentally and analytically investigated under different conditions. The results indicate that the structure can be reliably unfolded into the predefined shapes. In the case of Miura-SGRMO, the optimal surface precision is attained when the angle-ψ registers at 30°. The results of this study are expected to serve as the design of ultra-large flexible solar arrays and deployable antenna structures.

Soft-wing kites for airborne wind-energy harvesting function as flying tensile membrane structures, each of whose shape depends on the aerodynamic load distribution and vice versa. The strong two-way coupling between shape and loading poses a complex fluid-structure interaction problem. Since computational models for such problems do not yet meet the requirements of being accurate and at the same time fast, kite designers usually work on the basis of intuition and experience, combined with extensive iterative flight testing. This paper presents a fast aero-structural model of leading-edge inflatable kites for the design phase of airborne wind-energy systems. The fluid-structure interaction solver couples two fast and modular models: a particle system model to capture the deformation of the wing and bridle-line system and a 3D nonlinear vortex step method coupled with viscous 2D airfoil polars to describe the aerodynamics. The flow solver was validated with several wing geometries and proved to be accurate and computationally inexpensive for pre-stall angles of attack. The coupled aero-structural model was validated using experimental data, showing good agreement in the deformations and aerodynamic forces. Therefore, the speed and accuracy of this model make it an excellent foundation for a kite design tool. [ABSTRACT FROM AUTHOR]

As one of the most widely studied membrane systems, a spiking neural P system consists of three fundamental elements: initial spikes, evolution rules and connection between neurons. The automatic design of an arithmetic operation spiking neural P system (SN P system) in the literature usually considered the selection of the set of redundant rules under the condition of known initial spikes and connection between neurons. In this work, an automatic design method of arithmetic operation SN P systems including the encoding method and evolutionary strategy of arithmetic operation SN P systems is proposed to evolve an SN P system to achieve arithmetic operation. Experimental results show that the automatic design method of arithmetic operation SN P systems is feasible and effective for arithmetic operations. [ABSTRACT FROM AUTHOR]

Spinning membrane structures are of benefit to space applications because they can be deployed without such mass resources as booms. On the other hand, the lack of supporting structures can lead to undesirable deformations that are dominated by a complex partial differential equation. In this paper, an analytical description for transverse vibrations of spinning membranes is presented. It is shown that the eigenfunctions can be written using the Zernike polynomials; in the presented framework, however, a more practical representation that focuses on the physical characteristics of the vibrations is developed. Furthermore, response to external forces, or controls, is formulated by introducing an extended form of an impulse response function (IRF) that includes spatial information in addition to time information. The deformation under arbitrary forces can be calculated through a convolution integral with the extended IRF. Moreover, the Fourier transform of the IRF gives the frequency response function, which can be useful in designing a vibration control system. To verify the validity of the developed model, the analytical solution is compared to the numerical solution in the finite element analysis. Results demonstrate that both solutions agree in the modal analysis, frequency response analysis, and transient response analysis. [ABSTRACT FROM AUTHOR]

Design and execution of membrane structures according to prCEN/TS 19102 This paper reflects the progressive development of the first European design standard for membrane structures. It will be published in future as CEN/TS 19102 "Design of tensioned membrane structures". In addition to design rules, it will also contain interim execution rules based on the design concept. The current status of the planned regulations in these two areas is presented in this article. [ABSTRACT FROM AUTHOR]

Airborne wind energy systems using flexible membrane wings have the advantages of a low weight, small packing volume, high mobility and rapid deployability. This paper investigates the aero-structural deformation of a leading edge inflatable kite for airborne wind energy harvesting. In the first step, a triangular two-plate representation of the wing is introduced, leading to an analytical description of the wing geometry depending on the symmetric actuation state. In the second step, this geometric constraint-based model is refined to a multi-segment wing representation using a particle system approach. Each wing segment consists of four point masses kept at a constant distance along the tubular frame by linear spring-damper elements. An empirical correlation is used to model the billowing of the wing’s trailing edge. The linear spring-damper elements also the model line segments of the bridle line system, with each connecting two point masses. Three line segments can also be connected by a pulley model. The aerodynamic force acting on each wing segment is determined individually using the lift equation with a constant lift coefficient. The particle system model can predict the symmetric deformation of the wing in response to a symmetric actuation of the bridle lines used for depowering the kite (i.e., changing the pitch angle). The model also reproduces the typical twist deformation of the wing in response to an asymmetric line actuation used for steering the kite. The simulated wing geometries are compared with photogrammetric information taken by the onboard video camera of the kite control unit, focusing on the wing during flight. The results demonstrate that a particle system model can accurately predict the geometry of a soft wing at a low computational cost, making it an ideal structural building block for the next generation of soft wing kite models.

Acid-resistant nanofiltration (NF) membranes offer robustness in efficiently separating valuable resource and recycling waste acid in harsh acidic conditions. Yet, the existing ambiguity in understanding the structure-performance relationship of commercially available acid-resistant membranes leads to an unclear direction for designing innovative acid-resistant membranes and poses challenges in selecting suitable membranes for engineering applications. This work thoroughly examined the structural characteristics of commercially available membranes, assessed their effectiveness in removing heavy metals, and established a clear structure-performance relationship. Key findings include that superior permeability is attributed to the thinnest selective layer, higher separation precision is attributed to small pore size and narrow pore size distribution, exceptional acid stability should be owing to the sulfonamide structure, and medium-strength acid resistance of membranes is due to mixed sulfonamide-amide structures or extended carbon chain structures. Additionally, the work highlighted the contribution of dense and thick selective layers to membrane stability and the influence of surface characteristics on fouling removal. These insights provide valuable guidance for the structural design and selection of acid-resistant membranes in engineering applications, enhancing their effectiveness in diverse acidic environments. [Display omitted] • This work established the structure-performance relationship of three membranes. • Sulfonamide structure should be a direction for designing acid-resistant membrane. • Provided reference for selecting membranes in different acidic environments. [ABSTRACT FROM AUTHOR]

Soft-wing kites for airborne wind-energy harvesting function as flying tensile membrane structures, each of whose shape depends on the aerodynamic load distribution and vice versa. The strong two-way coupling between shape and loading poses a complex fluid-structure interaction problem. Since computational models for such problems do not yet meet the requirements of being accurate and at the same time fast, kite designers usually work on the basis of intuition and experience, combined with extensive iterative flight testing. This paper presents a fast aero-structural model of leading-edge inflatable kites for the design phase of airborne wind-energy systems. The fluid-structure interaction solver couples two fast and modular models: a particle system model to capture the deformation of the wing and bridle-line system and a 3D nonlinear vortex step method coupled with viscous 2D airfoil polars to describe the aerodynamics. The flow solver was validated with several wing geometries and proved to be accurate and computationally inexpensive for pre-stall angles of attack. The coupled aero-structural model was validated using experimental data, showing good agreement in the deformations and aerodynamic forces. Therefore, the speed and accuracy of this model make it an excellent foundation for a kite design tool.

There have been several advanced space missions using large gossamer space structures proposed recently, such as a spinning solar sail. However, only certain missions have been implemented, primarily because the on-orbit dynamic behavior of such structures cannot be precisely predicted through ground tests. To address this limitation, a scale law between a small- and a full-scale model of large membrane structures is proposed herein. In addition, small or reduced-order models for numerical simulations are proposed to reduce computation costs. However, the development of a small model, which has to be completely identical (geometrically) to the full-scale model, is challenging. Thus, a scale law between the small- and full-scale models of a large gossamer space structure, which is geometrically non-similar to the full-scale model, is also proposed. The scale law is also applied to the spin deployment motion of thin membrane and verified using numerical simulations. [ABSTRACT FROM AUTHOR]

Many satellites are currently in orbit around the Earth and will remain so for years, even though they have completed their intended missions owing to their long natural de-orbiting times. Many methods have been proposed to increase the de-orbiting speed of such satellites, of which one uses atmospheric drag sails. The micro-satellite ALE-1 is equipped with a drag sail that is deployed at a distance from the satellite through the use of a boom element to ensure continuous communication and solar charging. The drag sail is also capable of separating itself from the micro-satellite if necessary to decrease the de-orbiting speed. This paper discusses an in-orbit demonstration where the aforementioned boom element is extended, as well as the deployment of the aforementioned drag sail and compares the space and ground experiment results. [ABSTRACT FROM AUTHOR]

This contribution is focused on the design analysis of membrane structure and finding an optimal shape of such structure due to the surrounding possibilities with using numerical modeling. The membrane structure is designed for roofing of the experimental stand, which is in the campus of Faculty of Civil Engineering, VSB - Technical University of Ostrava and is currently not protected against unfavorable weather conditions. Design of membrane structures as temporary or permanent roofing has recently become very popular because of its shape variability, very low weight, and possibility of large spans. However, in addition to aesthetic requirements, structural and dispositional requirements are also necessary to consider on the same level during the design. The aim of this paper is to give an overview of the design of the temporary membrane structure starting from the architectural visualization and continuing to deal with structural and dispositional parts of the design using the RFEM software which has special add - on module for nonlinear analysis of membrane structures, RF Form - Finding. [ABSTRACT FROM AUTHOR]

El auge y desarrollo de las herramientas de diseño, edición y fabricación digital en la producción arquitectónica, ha permitido que arquitectos e ingenieros puedan materializar elementos con una gran complejidad programática y formal y con un comportamiento estructural eficiente. La aplicación a la producción arquitectónica de los principios que están presentes en las superficies mínimas con estructura cristalina es de interés para el diseño, edición y fabricación digital de nuevas soluciones arquitectónicas basadas en superficies continuas, complejas y eficientes con una alta capacidad de prefabricación. La investigación presenta como pueden obtenerse y fabricarse con métodos digitales avanzados de diseño y fabricación, como la impresión 3D aditiva, una gran variedad de nuevas topologías arquitectónicas modulares, que pueden conformar en ocasiones agrupaciones complejas y porosas Abstract The rise and development of design, editing and digital manufacturing tools in architectural production has allowed architects and engineers to materialize elements with great programmatic and formal complexity and efficient structural behavior. The application to architectural production of the principles that are present in the minimum surfaces with crystalline structure is of interest for the design, edition and digital fabrication of new architectural solutions based on continuous, complex and efficient surfaces with a high prefabrication capacity. The research presents how a wide variety of new modular architectural topologies can be obtained and manufactured with advanced digital design and manufacturing methods, such as additive 3D printing, which can sometimes form complex and porous clusters

Miura-ori is a rigid origami structure utilized in the packaging of deployable solar panels for use in space or in the folding of maps. It's pattern can largely reduce the membrane stress and improve the work efficiency. Inspired by origami structures, we numerically and experimentally studied a scalable solar sail structure. As an improvement of the existing membrane simulations, a variable Poisson's ratio model considering the wrinkling effect of the membrane was introduced. We focused on a quadrant shape and studied how its geometry parameters and initial imperfections affect the membrane mechanical behavior. We also designed and fabricated a pantographic mechanism as an origami membrane actuator. In addition, design protocols of deployment applied to a scalable gossamer structure were proposed. [ABSTRACT FROM AUTHOR]

Deployable structures facilitate the reduction of the stowed volume in CubeSat. In this investigation, an initially deflected panel called a “convex-panel” is proposed. The convex-panel generates a self-deployment force during deployment and has a higher bending stiffness after deployment with a reduced thickness. This results in a reduction in the stowed volume of the deployable flatpanel structures. To demonstrate the feasibility of the convex-panel, deployment experiments were conducted with conceptual models. Based on these experiments, higher self-deployment velocities were observed in the beginning and the last deployment stages, and complete deployment was achieved via appropriate arrangements of the convex-panels. These results demonstrated the feasibility of the convex-panel for the self-deployable structures used in CubeSat. [ABSTRACT FROM AUTHOR]

Biological membranes (short: biomembranes) are one of the most complex structures that allow life to exist. They play an important role not only as an effective structural barrier separating and protecting an internal environment from an external environment, but also provide an area of significant biological activities made possible with the help of various functional macromolecules, including phospholipids, cholesterol, proteins, and carbohydrates. In recent years, computer simulations have become popular (and complement laboratory experiments) to explore the intricate interplay between these molecules over spatial and time scales. This article provides information about the characteristics of biomembranes and reviews recent advances in computational studies as is described in the book on biomembrane simulations by Max L. Berkowitz.

Deployable membrane structures such as inflatable stratospheric balloons are known to be sensitive to the occurrence of local instabilities such as wrinkles. The wrinkling phenomenon affects the working performances of the membrane and the occurrence of this phenomenon has to be controlled numerically in order to predict the best means of deployment during the inflation of aerospace balloons. To improve their performances and reliability during flight, the balloons also need to be sized appropriately without the stress field being disturbed by the wrinkles. These instabilities originate numerically from the membrane elements which have a negligible bending stiffness. Several wrinkling models have been presented in the literature in order to solve this problem. However, in most of these models an elastic law and the Green deformation approach have been used for this purpose. The new model called the PS-DPS model presented here for correcting the effects of wrinkles on membrane structures was implemented in the in-house finite element software Herezh++. A projection technique based on a Newton–Raphson method is used to control the stress plane and the in-plane contraction. Using the Almansi strain formulation, this model also accounts for the changes in membrane thickness liable to occur during simulations. The problems due to numerical instabilities are overcome by determining the equilibrium with the so-called Dynamic Relaxation method using kinetic damping procedures. Unlike other membrane models of literature, the PS-DPS model can be used with materials showing complex mechanical behaviour of all kinds. Several benchmark problems are analysed with the present wrinkling model and compared with results available in the literature, focusing first on an elastic law and then on a non-linear hyperelastic law. Lastly, the inflation of a square cushion test and that of a Zero Pressure Balloon are simulated with this non-linear law. The results obtained indicate that the PS-DPS model is valid and accurate to take into account the wrinkles in flexible structures with all these linear and non-linear behaviours. [ABSTRACT FROM AUTHOR]

Thin glass offers a promising prospect for lightweight façades with reduced use of raw materials, also opening up entirely new perspectives for architectural expression with its excellent optical quality as well as its high flexibility. The realisation of projects featuring thin glass as a structural element is so far limited due to several challenges led by structural issues mainly induced by the product's low stiffness. This paper attempts to bypass this issue by exploring the possibilities of the structural application of thin glass as a membrane element using examples of all-glass projects from the past as well as researches conducted in the present. The use of thin glass as a compressive member is impractical since the risk of buckling poses a greater threat than stress exceedance. As an alternative, its application as a tensile member is proposed, supported by examples from academic and industrial researches. In this context, a new type of glass support is introduced, enabling a moment-free load transfer into the glass.

The CAD‐integrated parametric design process of membrane structures The design of membrane structures entails three strongly linked and often very interactive disciplines: formfinding, structural analysis and cutting pattern generation. Powerful numerical tools and environments are needed for the design of a viable membrane structure while consistently performing the necessary analyses. CAD‐integrated analysis allows for the performance of these highly non‐linear analyses within the CAD environment. This leads to an optimal geometry description for the analysis model, since it is modeled with smooth NURBS curves and surfaces. Furthermore, the links between analysis steps can be modeled ideally within the CAD framework that contains both pre‐ and postprocessing. A formfound geometry can e. g. directly be used for consecutive analyses. The basis for this is Isogeometric B‐Rep Analysis (IBRA), which will be explained briefly in this paper. In the isogeometric method, NURBS are used for the basis functions of Finite Element Method as well as the geometry description. The parametrization of geometric and mechanical properties enables the fully integrated performance of formfinding, structural analysis and patterning based on a common numerical model. The consideration of nearly infinite configurations of one model is thus provided with a minimum of effort. This article presents an overview of current methods and advantages of the parametric CAD‐integrated design cycle. The plugin Kiwi!3D for Rhino and Grasshopper is used for the demonstration and the mechanical basis of all design steps will be laid out. The textile roofs of the Cologne Tanzbrunnen serve as exemplary structures. [ABSTRACT FROM AUTHOR]

The stiffness of membrane structures widely used in modern buildings is provided by pre-tension, which means that any loss of pre-tension during service life may endanger structural safety and lead to engineering accidents. Therefore, the pre-tension of membrane structures needs to be estimated effectively and a corresponding estimation method is proposed in this study. Firstly, a theoretical model of a rectangular membrane structure is established using the constant deflection contour method (CDCM) to analytically derive a relationship between the pre-tension and the frequency. Then, the pre-tension is calculated using the frequency obtained experimentally by non-contact modal testing using a three-dimensional digital image correlation (3D-DIC) technique. Furthermore, the estimation method is validated by experimental study. The results show that the proposed method can provide a satisfactory assessment of the pre-tension in rectangular membrane structures and has significant potential to be utilised by industry. [ABSTRACT FROM AUTHOR]

The stability of the membrane's dynamic layer consisting of polystyrene (PS) microparticles is studied. To improve the stability, a nylon-PS membrane is subjected to thermal treatment at temperatures of 50 to 100°C for 10 min. The effect of heat treatment on the surface of the dynamic membrane is studied by scanning electron microscopy and wetting angle measurements. The stability of the dynamic layer is achieved by 10-min thermal treatment at 50°C, with the stability of the dynamic layer increasing by a factor of four. After a backflush with a solution of anionic surfactants, the membrane's weight does not decrease, while the weight of the initial nylon-PS membrane decreases by 0.84%. In addition, use of membranes with a thermally stabilized dynamic layer raises the degree of separation of a water–oil emulsion from 97 to 99%. [ABSTRACT FROM AUTHOR]

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

Introduction: The molecular pathogenesis of Alzheimer's disease (AD) is still not clear, and the relationship between gene expression profile for different brain regions has not been studied. Objective: Bioinformatic analysis at the genetic level has become the best way for the pathogenesis research of AD, which can analyze the abovementioned relationship. Methods: In this study, the datasets of AD were obtained from the Gene Expression Omnibus (GEO), and Qlucore Omics Explorer (QOE) software was used to screen differentially expressed genes of GSE36980 and GSE9770 and verify gene expression of GSE63060. The Gene Ontology (GO) function enrichment analysis of these selected genes was conducted by Database for Annotation, Visualization, and Integrated Discovery (DAVID), and then the gene/protein interaction network was established by STRING to find the related proteins. R language was used for drafting maps and plots. Results: There were 20 differentially expressed genes related to AD selected from GSE36980 (p = 6.2e−6, q = 2.9422e−4) and GSE9770 (p = 3.3e−4, q = 0.016606). Their expression levels of the AD group were lower than those in the control group and varied among different brain regions. Cellular morphogenesis and establishment or maintenance of cell polarity were enriched, and LRRTM1 and RASAL1 were identified by the integration network. Moreover, the analysis of GSE63060 verified the expression level of LRRTM1 and RASAL1 in Alzheimer's patients, which was much lower than that in normal people aged >65 years. Conclusions: The pathogenesis of AD at molecular levels may link to cell membrane structures and signal transduction; hence, a list of 20 genes, including LRRTM1 and RASAL1,potentially are important for the discovery of treatment target or molecular marker of AD. [ABSTRACT FROM AUTHOR]

• The Natural Force Density Method (NFDM) is an effective method for the shape-finding of membranes and funicular shell structures. • NFDM converts the generally nonlinear shape-fiding problem into a linear equilibrium problem, providing viable shapes on a single step, but without full control of the associated stress field. • NFDM allows the use of non-uniform meshes and imposition of more general stress fields, compared to other available methods. • A new quadrangular element is presented, providing further generalization of the NFDM, with improved performance, if compared to the original triangular element. The Natural Force Density Method (NFDM) is a convenient method for finding configurations of membranes and funicular shell structures, providing viable equilibrium geometries in a single linear equilibrium analysis. It is an extension of the Force Density Method (FDM), first proposed by Linkwitz in 1971, as convenient alternative for finding configurations of cable nets, which became ubiquitous in the field of membrane design, serving as basis of several successful computer programs. However, the equivalence between a network of force density elements and a continuous membrane is far from obvious, and it may become quite dubious which force densities should be prescribed, to achieve a desired configuration, comprising a geometric shape and an associate stress field. This is seldom remarked in papers about the method, and even less aware of that might be the general users the of programs based on it. The NFDM, first proposed by Pauletti in 2006, treats directly the continuous problem, overcoming the difficulties of FDM to deal with irregular meshes. Nevertheless, the NFDM was originally proposed considering the triangular membrane element introduced by Argyris in 1974, and thus required a fully triangular tessellation of a reference domain. In this paper we present a more concise deduction and systematic outline of the NFDM, as well as a simple extension of the method to quadrangular elements, allowing the use of more general mesh generators for the initial references meshes, and selection of a broader class of membrane or shell finite elements, afterwards. [ABSTRACT FROM AUTHOR]

Temporary pavilions play an important role as experimental fields for architects, designers, and engineers, in addition to providing exhibition spaces. Novel structural and formal solutions applied in pavilions also can give them an unusual appearance that attracts the eyesight of spectators. In this article, the authors explore the possibility of combining structural novelty, visual attractiveness, and low cost in the design and construction of a temporary pavilion. For that purpose, an innovative structural system and design approach was applied, i.e., a membrane structure was designed in Rhino and Grasshopper environments with the use of the Kiwi!3D IsoGeometric analysis tool. The designed pavilion, named Obverse/Reverse, was built in Opole, Poland, for the occasion of World Architecture Day in July 2019. The design and the construction were performed by the authors in cooperation with students belonging to the Humanization of Urban Environment organization from the Faculty of Architecture Wroclaw University of Science and Technology. The resultant pavilion proved the potential of obtaining a low-budget but visually attractive architectural solution with the adaption of parametrical design tools and some scientific background with innovative structural systems.

Migratory cells use distinct motility modes to navigate different microenvironments, but it is unclear whether these modes rely on the same core set of polarity components. To investigate this, we disrupted actin-related protein 2/3 (Arp2/3) and the WASP-family verprolin homologous protein (WAVE) complex, which assemble branched actin networks that are essential for neutrophil polarity and motility in standard adherent conditions. Surprisingly, confinement rescues polarity and movement of neutrophils lacking these components, revealing a processive bleb-based protrusion program that is mechanistically distinct from the branched actin-based protrusion program but shares some of the same core components and underlying molecular logic. We further find that the restriction of protrusion growth to one site does not always respond to membrane tension directly, as previously thought, but may rely on closely linked properties such as local membrane curvature. Our work reveals a hidden circuit for neutrophil polarity and indicates that cells have distinct molecular mechanisms for polarization that dominate in different microenvironments. [ABSTRACT FROM AUTHOR]

IKAROS, a solar sail spacecraft launched in 2010, demonstrated that thin-film solar cells can generate electricity. During this demonstration, it was found that the cells became curved, which destabilized the attitude of the spacecraft. Therefore, this study focused on a sputtering deposition technique that generates internal stress during the formation of thin films. The objective of this study was to control the curvature of a multilayer film by sputtering with a pattern. The effect of sputtering on the thin film was analyzed through experiments and simulations, and it was clarified that the cause of shape non-reproducibility is sputtering-induced stress. [ABSTRACT FROM AUTHOR]

Trial design: During electrical stimulation in the lower urinary tract for the purpose of current perception threshold and sensory evoked potential recording, we observed that bladder volume increased rapidly. The aim of this prospective randomised comparative proof-of-concept study was to quantify urine production per time during stimulation of the lower urinary tract using different stimulation frequencies. Methods: Ninety healthy subjects (18 to 36 years old) were included. Forty females and 50 males were randomly assigned to one of the following study groups: dome, trigone or proximal, membranous (males only) or distal urethra. Starting from 60mL prefilling, stimulation was performed at two separate visits with a 14 French custom-made catheter using randomly applied frequencies of 0.5Hz, 1.1Hz, 1.6Hz (each with 500 stimuli). After each stimulation cycle per frequency, urine production was assessed. Main outcome measures represented urine production during stimulation, daily life and their ratio. Results: Lower urinary tract electrical stimulation increased urine production per time compared to bladder diary baseline values. Linear mixed model showed that frequency (p<0.001), stimulation order (p = 0.003), intensity (p = 0.042), and gender (p = 0.047) had a significant influence on urine production. Location, visit and age had no significant influence. Conclusions: Urine production is increased during electrical stimulation with a bigger impact of higher frequencies. This might be relevant for methodological aspects in the assessment of lower urinary tract afferent function and for patients with impaired renal urine output. Inhibition of renal sympathetic nerve activity by vagal afferents may be the underlying mechanism. [ABSTRACT FROM AUTHOR]

The forces that arise from the actin cortex play a crucial role in determining the membrane deformation. These include protrusive forces due to actin polymerization, pulling forces due to transient attachment of actin filaments to the membrane, retrograde flow powered by contraction of actomyosin network, and adhesion to the extracellular matrix. Here we present a theoretical model for membrane deformation resulting from the feedback between the membrane shape and the forces acting on the membrane. We model the membrane as a series of beads connected by springs and determine the final steady-state shape of the membrane arising from the interplay between pushing/pulling forces of the actin network and the resisting membrane tension. We specifically investigate the effect of the gel dynamics on the spatio-temporal deformation of the membrane until a stable lamellipodium is formed. We show that the retrograde flow and the cross-linking velocity play an essential role in the final elongation of the membrane. Interestingly, in the simulations where motor-induced contractility is switched off, reduced retrograde flow results in an increase in the rate and amplitude of membrane protrusion. These simulations are consistent with experimental observations that report an enhancement in protrusion efficiency as myosin II molecular motors are inhibited. [ABSTRACT FROM AUTHOR]

We study the crucial role of membrane fluctuations in maintaining a narrow gap between a fluid membrane tube and an enclosed solid particle. Solvent flows can occur in this gap, hence giving rise to a finite particle mobility along the tube. While our study has relevance for how cells are able to transport large organelles or other cargo along connecting membrane tubes, known as tunneling nanotubes, our calculations are also framed so that they can be tested by a specific in vitro experiment: A tubular membrane tether can be pulled from a membrane reservoir, such as an aspirated Giant Unilamellar Vesicle (GUV), e.g. using a conjugated bead that binds to the membrane and is held in a laser trap. We compute the subsequent mobility of colloidal particles trapped in the tube, focusing on the case when the particle is large compared to the equilibrium tube radius. We predict that the particle mobility should scale as ∼ σ−2/3, with σ the membrane tension. [ABSTRACT FROM AUTHOR]