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Building air leaks (both through exterior and interior surfaces) can have a significant impact on energy consumption, indoor air quality, fire safety, and moisture accumulation affecting structural durability. Blower door testing has been used to measure leaks in buildings, but commonly used testing methods do not directly measure interior leaks. In this paper, new testing methods (guarded interior test and zonal multipoint pressure testing method) are presented that directly measure these interior leaks, utilizing common blower door equipment for both single and multi-point testing. These new methods are compared to conventional methods in terms of the information provided, limitations and time/effort needed. In addition, building leak measurement results are analyzed to reveal (a) coupling between power law model values (exponent and coefficient) for an ensemble of buildings, (b) the error in using single point testing when estimating low pressure leakage, and (c) how building power law models vary from low to high pressure ranges. [ABSTRACT FROM AUTHOR]

Inflatable membrane structures are the state-of-the-art fast evolving space structures owing to its inherent advantages such as lightweight, higher packaging efficiency along with ease of deployment. The membrane reflectors need to be actuated by adequate tension forces to get the required surface accuracy. The design of tensioning device has certain challenges, such as mass penalty, low packaging efficiency and power source dependency. The present study demonstrates the novel design methodology for the tensioning system for the inflatable paraboloid membrane reflector antenna using the wave springs. The loading analysis of the inflatable paraboloid reflector is carried out for adequate inflation pressure and tension forces maintaining the surface error within the tolerance limit. The numerical results of the loading analysis are compared and found to be consistent with the experimental findings. The relation between the displacement of tensioning spring and the dimensions of supporting inflatable torus is established. The results show that wave springs can successfully transfer the required tension forces to the reflector with required surface accuracy. The findings of this research provide insights for simple, lightweight, packaging efficient and cost-effective design solution to the tensioning system for inflatable paraboloid reflector antenna. [ABSTRACT FROM AUTHOR]

Buildair S.A. has designed, manufactured and built an inflatable hangar (called hangar H75) for the aeronautical industry at Jeddah Airport, Kingdom of Saudi Arabia. H75 is the largest air-cell inflated structure ever built in the world, finally erected in July 2019. The structural analysis and design of the main body of the hangar has involved complex structural concepts due to the specificity of the structural elements employed, like membranes and straps that lead to a highly nonlinear mechanical problem, or the treatment of wind over the structure without a defined standard for inflatable structures. In this article, the structural concept and specificities of the structure are presented, as well as the design procedure for H75 based on numerical analysis, to fulfil the design requirements in terms of stress and deformation of the main body. [ABSTRACT FROM AUTHOR]

The sauropod genus Mamenchisaurus, from the Late Jurassic–Early Cretaceous of East Asia, has a convoluted taxonomic history. Although included in the first cladistic analysis of sauropods, only recently has the monophyly of Mamenchisaurus, and the anatomical diversity of the many penecontemporaneous East Asian eusauropods, been evaluated critically. Here, we re-describe the holotype and only specimen of M. sinocanadorum. Although the original diagnosis is no longer adequate, we identify several autapomorphies that support the validity of this species, including an elongate external mandibular fenestra and distinctive pneumatic structures on the cervical centra. We incorporate new data into a phylogenetic character matrix that also includes Bellusaurus and Daanosaurus, both of which are known only from juvenile material and are often hypothesized to be neosauropods (or close relatives thereof). We recover all species of Mamenchisaurus as part of a radiation of predominantly Middle–Late Jurassic East Asian eusauropods, but the genus is non-monophyletic, underscoring the need for further systematic revision of mamenchisaurid taxonomy. Analyses that score ontogenetically variable characters ambiguously recover Bellusaurus and Daanosaurus as juvenile mamenchisaurids, a hypothesis supported by several features that are unique to mamenchisaurids or exhibit little homoplasy, including anteriorly bifurcate cervical ribs. Finally, computed-tomography reveals extensive vertebral pneumaticity in M. sinocanadorum that is comparable to that of the largest sauropods, and updated scaling analyses imply a neck over 14 m long, rivalling estimates for other exceptionally long-necked sauropods. Previous work has suggested that the elongated cervical ribs of particularly long-necked sauropods such as M. sinocanadorum stabilized the neck by limiting its mobility. Given that extent of pneumaticity responds dynamically to a bone's habitual loading, we propose that long cervical ribs – and other structural modifications that limited flexibility – promoted the evolution of increasingly long necks by producing a more predictable biomechanical milieu amenable to increased pneumatization. [ABSTRACT FROM AUTHOR]

Shunosaurus is a small eusauropod from China. It is characterised by solid cervical and dorsal vertebral centra without complicated pneumatic structures, platycoelous or amphicoelous middle and posterior vertebrae and a lack of pubic foramen in adult individuals. Although many Shunosaurus individuals have been discovered, the ontogenetic characteristics of its long bones and bone tissues are not very clear and the existing description of the postcranial skeleton is relatively rudimentary. The new well-preserved and the smallest Shunosaurus specimen discovered in Yunyang, Chongqing, China, provides good material for solving these problems. The radial distal breadth is more than twice the minimum midshaft breadth, and the fibular distal end is twice as wide as the midshaft, while these ratios are all smaller in adult specimens. The lateral trochanter is undeveloped. This individual does show a pubic foramen. The degree of vascularisation of the bone tissue in the juvenile bone tissue is higher for adults. There are no arrested growth lines and peripheral rest lines in the compact bone, indicating that body size still increases slowly after maturity. The discovery of this new material expands the distribution range of Shunosaurus in China. [ABSTRACT FROM AUTHOR]

Like all structural elements, inflatable beams can be subjected to combined loads. This may be the case for inflatable masts or inflatable columns supporting floors. This study addresses inflatable beams subjected to combinations of compression and bending. Whereas the mechanics of inflatable beams subjected only to transverse loading is now well established, the study of inflatable beams subjected to combined loads has still received few investigation. Furthermore, whereas the effects of individual loads are superimposed when beams are made of conventional materials such as steel, the problem is more complex for inflatable beams since compressive forces counteract the effects of internal pressure and reduce the stiffness. This study presents new analytical formulas for inflatable beams subjected to bending and compressive loads. Buckling load and wrinkling limit load are also proposed, taking into account the internal pressure. [ABSTRACT FROM AUTHOR]

Inflatable structures are part of the family of tensioned textile membrane structures. The operating principle is common for all these type of structures: the stiffness of the structure relies on the tensioning of the membrane, which is generally provided by a mechanical device in the case of tensile structures, and by setting the pressure in the case of pneumatic structures. These structures are the subject of a European standardisation process to harmonise the methods of calculation and design. We propose here a first reliability study on a two parallel inflatable beams structure which can be used as a footbridge. The serviceability limit states (SLS) and ultimate limit state (ULS) are defined. The reliability analysis is conducted with the First Order Reliability method, providing reliability indices as well as sensitivity factors. [ABSTRACT FROM AUTHOR]

Fossil-rich deposits from the Middle and Late Jurassic of China have yielded a diverse array of sauropod dinosaurs, including numerous species referred to Mamenchisaurus and Omeisaurus. Despite an abundance of fossils and a proliferation of taxa, the anatomy of Middle–Late Jurassic Chinese sauropods remains poorly documented. Here, we comprehensively redescribe and illustrate Klamelisaurus gobiensis from the Middle–Late Jurassic Shishugou Formation of northwest China. Phylogenetic analyses conducted under parsimony and time-calibrated Bayesian optimality criteria consistently recover Klamelisaurus as a member of a predominantly Chinese radiation of exceptionally long-necked eusauropods that includes Mamenchisaurus spp., Chuanjiesaurus, Qijianglong and Wamweracaudia. In most analyses, this lineage also includes Euhelopus, reviving a 'traditional' Euhelopodidae and calling into question the macronarian affinities of Euhelopus. Klamelisaurus shares several features with Euhelopus that are unique to a subset of East Asian taxa or rare among sauropods, including a convex ventral margin of the prezygodiapophyseal lamina in middle–posterior cervical vertebrae, a ventrally bifurcated postzygodiapophyseal lamina in posterior cervical vertebrae, and development of a rugose projection extending anteriorly from the epipophysis into the spinodiapophyseal fossa in most cervical vertebrae. Anatomical comparisons of the cervical vertebrae of Klamelisaurus to several other sauropodomorphs and insights from myological studies of extant archosaurs strongly suggest that this latter structure, often considered part of an epipophyseal-prezygapophyseal lamina, is an epaxial muscle scar that is distinct from pneumatic structures of the lateral surface of the neural spine. The phylogenetic and comparative anatomical data presented here provide a foundation for future revision of the taxonomy and systematics of sauropods from the Junggar and Sichuan basins. [ABSTRACT FROM AUTHOR]

In 1970, the Museum of Contemporary Crafts in New York City hosted the exhibition Haus-Rucker-Co LIVE!, a mid-career retrospective of the Viennese architectural collective. Most historians have studied the range of design works created by the trio—and featured in the exhibition—alongside contemporaneous architects' concerns with sci-fi fantasy; temporary, inflatable structures; and countercultural liberation. While not ignoring the emancipatory potential of these works, this essay focuses primarily on the set of performative actions Haus-Rucker-Co staged within the museum during the run of the exhibition, including: their decision to live within the museum galleries, the hosting of weekly meals in the exhibition space, and the ritual devouring of a scale model of the museum made out of cake. Taken together, these acts foreground a sense of sociality and community that counters the museum's standard emphasis on individualized aesthetic absorption. [ABSTRACT FROM AUTHOR]

American architect Victor Lundy designed an inflatable pavilion to house the traveling Atoms for Peace exhibition in 1960. This pavilion constituted a literal atmosphere because the difference between its internal and external air pressure functioned as the structural element. The pavilion also produced an experiential atmosphere that, like the exhibition within, used technological progress to suggest a better world to come. In this paper, I recover the little-known history of Lundy's pavilion to expand its atmospheric dimensions to include not only the literal and experiential but also the sociopolitical. Such an expansion reveals the ideological pressures that shaped the pavilion and, more generally, the changing meanings of inflatable architecture during the postwar period. [ABSTRACT FROM AUTHOR]

Many soft actuators have been studied for use in robots that come into contact with humans, including communication, entertainment, and medical/health care robots. One reason for this is that soft robots are expected to exhibit intrinsic safety in case an accident occurs. This paper proposes a plastic-film pneumatic actuator with a pleated structure that do not undergo the elastic deformation typical of rubber materials. By utilizing thin plastic films, the mass of an actuator can be significantly reduced, even if the actuators are the same size as a human arm. If the mass of the actuator is reduced, the kinetic energy when contacts with humans mechanically can be reduced considerably without reducing the working speed. More specifically, we propose a pleated structure made of plastic to achieve structural deformation generated from a two-dimensional pleated film. The pleated structure easily generates various bending motions. In this paper, a design method for determining the shape parameters of the pleated actuator structure using approximate models with considering measurement results of generating force is presented. We evaluated the adequacy of our approach in experiments using sample actuators. Furthermore, we show the constraints required to determine the necessary parameters. Thus, this paper provides an easy method for designing a lightweight and flexible plastic-film actuator. [ABSTRACT FROM AUTHOR]

The deployable structures based on shape memory polymer composites (SMPCs) have been developed for its unique properties, such as high reliability, low-cost, lightweight, and self-deployment without complex mechanical devices compared with traditional deployable structures. In order to increase the inflatable structure system's robustness and light the weight of it, a cubic deployable support structure based on SMPC is designed and analyzed preliminarily. The cubic deployable support structure based on SMPC consists of four dependent spatial cages, each spatial cage is composed of 12 three-longeron SMPC truss booms and end connections. The shape recovery of arc-shaped deployable laminates drive the three-longeron SMPC truss booms to unfold, thus realize the expansion of the deployable support structure. The concept and operation of the cubic deployable support structure are described in detail. A series of experiments are performed on the three-longeron deployable laminates unit and the simplified cubic deployable support structure to investigate the shape recovery behavior in the deployment process. Results indicate that the cubic deployable support structure has a high deployment-tgostowage volume ratio and can achieve self-deployment, package, and deploy without complex mechanical devices. [ABSTRACT FROM AUTHOR]

Autonomous systems with periodic solutions are frequently encountered in applications. In this paper, the Melnikov function and the theory of Poincare mapping were obtained for the existence of 2 π-periodic solution of the sandwich plate system in 1:2 internal resonances. Moreover, some groups of phase diagrams under different conditions were obtained. This paper reveals the flutter and pneumatic elastic properties of the sandwich plate, and it is expected that the results in this paper could provide the theoretical basis for the design of the composite materials. [ABSTRACT FROM AUTHOR]

Inflated booms are under increasing application in various membrane spacecraft structures. A specific emphasis is often placed on determining static characteristics of inflated beams in bending. There is a lack of knowledge in dynamic conditions, especially for simple and accurate solutions for wrinkled inflated beams. This article deals with the theoretical evaluation on the natural frequencies of wrinkled inflated beams. Three factors, including the inflated pressure, the wrinkles, and the aspect ratio, are introduced into the vibration equation of the beam to predict the first-order natural frequency of the wrinkled inflated beams. The predictions on the first-order natural frequency agree well with the vibration simulations. The parametric studies on the vibration characteristics of the wrinkled inflated beam are performed in the end. Results reveal that the wrinkles decrease the first-order natural frequency of the inflated beam greatly. The first-order frequency of the wrinkled inflated beam is sensitive to the aspect ratio. The results and conclusions are good references to the design and the wrinkling control of the inflated booms. [ABSTRACT FROM AUTHOR]

Experimental methods have been employed to acquire shear properties, examine buckling, and postbuckling response, and to characterize out-of-plane deformations of thin orthotropic polyurethane-coated nylon fabric designated for use in the finite element analysis of an inflatable structure. A custom-designed bi-axial pre-tension frame, a picture-fame rig, and a photogrammetry system were used to apply pre-tension, collect the angular and linear displacements, and to capture the buckling and wrinkle-forming mechanisms in the coupons during the shear test. The series of monotonic picture-frame tests provided with an average critical shear stress of 0.16 MPa that was required to buckle the coupons for a small range of the pre-tension force. While an average pre-buckling shear modulus (28.5 MPa) was obtained, only 2.25% of a relative difference between the average post-buckling apparent shear modulus (13.07 MPa) and the average shear modulus obtained from the 45° bias-extension test for the same material (13.36 MPa) was registered. The influence of the pre-tension not only on the initial buckling resistance and the transition point to the fully developed diagonal tension folds but also on a reduced resistance to the material damage during cyclic testing was investigated. A series of cyclic picture-frame tests gave the continuous load/unload response with appreciable hysteresis characteristics of the in-plane stress–strain with an average 10% of material degradation. When compared with the envelope of material resistance in the monotonic tests, during cycling loading, the coupons lost on average 13.9% more of its initial stress-carrying capability. The photogrammetry results allowed for the three-dimensional reconstruction of the coupon’s surface and the development of the deformation relationships between the effective force exerted on the coupons, the shear angle, and the geometric deformation variables for the wrinkles formed in the diagonal tension fold. The geometric deformation parameters, such as frequency of wrinkle formation, widths of the base and the tip, depths, the deformation angle, and the distances between the centerlines of the wrinkles occurring in the test coupon, were acquired with photogrametry and analyzed numerically with custom-written Matlab®code. [ABSTRACT FROM PUBLISHER]

Experimental procedures have been developed to obtain the mechanical stiffness and strength properties of an orthotropic polyurethane-coated nylon fabric for use in a finite element analysis of an inflatable, deployable structure. A method that utilizes a specialized material test fixture and photogrammetry to collect the linear and angular displacement data has been employed. Different material holding methods were compared with the objective of producing strength values not influenced by gripping and that allow for use of machine displacement to estimate longitudinal strains during cyclic testing. A series of tension and bias tension tests provided material properties such as Young’s modulus in both warp and fill directions, Poisson’s ratios in plane and through the thickness, and shear modulus. Results obtained from the photogrammetry method show good correlation to machine readings using a pinched gripping method. Additionally, cyclic tests gave the continuous load–unload response and the hysteresis characteristics of the stress–strain in plane and indicated the degree of material degradation. The shear stress–shear strain behavior and shear modulus values are acquired using bias tension tests on 45° skewed specimens. [ABSTRACT FROM PUBLISHER]

The article discusses on the Metriorhynchids, which is the only clade of extinct aquatic crocodyliforms. It states that they have elongated snouts, homodont dentition, paddle-like forelimbs, and hypocercal tail. It mentions that according to anatomical studies of extant crocodilians, the antorbital opening has been related to pneumatization of the archosaur skull, being the osteological correlate of the development of a conspicuous paranasal chamber connected with the fenestra. It states that there is absence of feature like preorbital opening and fossa of metriorhynchids in basal thalattosuchians is the adaptations of these forms. It states that the fenestra in basal thalattosuchians must have included anatomical changes in the excretory and pneumatic structures in the rostrum.

This paper presents two numerical modeling approaches to analyze the wrinkles in the space membrane structures. The nonlinear buckling method based on our wrinkle analytical technique incorporating ANSYS thin shell element is used to simulate the wrinkle characteristics in the plane membrane. The explicit time integration method incorporating the AIRBAGS model in LSDYNA code is used to predict the dynamic wrinkle characteristics and the stress state of inflatable membrane structures. Numerical approaches presented in this paper are applied in two numerical studies. One is the wrinkle analysis of the square plane membrane subjected to symmetric corner tension, and the other is the analysis of the square inflatable membrane airbag under the action of the internal variable inflatable pressure. The detailed wrinkling information, such as wrinkle wavelength, wrinkle amplitude, wrinkle region and the stress state of the wrinkled membrane structures, can be accurately obtained by using the approaches presented in this paper. Comparisons were made with experimental results for the wrinkle shape and distribution. The numerical predictions agreed well with the experimental results. The wrinkling results from the numerical computation can be used to support the studies on the nonlinear behaviors of the space membrane structures. [ABSTRACT FROM AUTHOR]

Nanofibrious composite poly(lactide-co-glycolide) (PLGA) and chitosan/poly(vinyl alcohol) (PVA) membranes were prepared by simultaneously electrospinning PLGA and chitosan/PVA from two different syringes. The in vitro degradation of PLGA and cross-linked composite membranes was examined for up to 10 weeks in phosphate-buffered saline (PBS, pH 7.4) at 37°C. The pH of PBS, the weight average molecular weight of PLGA, fiber morphology and mechanical properties, including tensile strength, Young's modulus and elongation-at-break, were measured as a function of degradation time. The fibrous composite membranes were further investigated as a promising scaffold for human embryo skin fibroblasts (hESFs) culture. The cell adhesion and morphology of hESFs seeded on each electrospun membrane was observed using scanning electron microscope and inverted phase contrast microscopy after Wright–Giemsa staining. The introduction of chitosan/PVA component changed the hydrophilic/hydrophobic balance and, thus, influenced degradation behavior and mechanical properties of the composite membranes during degradation. The cells could not only favorably attach and grow well on the composite membranes, but were also able to migrate and infiltrate the membranes. Therefore, the results suggest that the composite membranes can positively mimic the structure of natural extracellular matrices and have the potential for application as three-dimensional tissue-engineering scaffolds. [ABSTRACT FROM AUTHOR]

An air nozzle having a axial angle of 50° and inner diameter of 2.2 mm was placed below the front roller nip in a ring frame, at various distances. Simulation of the airflow pattern inside the nozzle provides some useful insight into the actual mechanism of hairiness reduction. A CFD (computational fluid dynamics) model has been developed to simulate the airflow pattern inside the nozzle using Fluent 6.1 software, to solve the three-dimensional flow field. To create a swirling effect, four air holes of 0.4 mm diameter are made tangential to the inner walls of the nozzle. Airflow directions viz., against and along the direction of yarn movement are studied by changing the nozzle position, and the best results are obtained for the former case. Thirty tex Z-twisted ring spun yarns were produced with and without nozzle and tested for hairiness, tensile, and evenness properties. The total number of hairs equal to or exceeding 3 mm (i.e., the S3 values) for yarn spun with nozzle (NozzleRing yarn) is nearly 36-58% less than that of ring spun yarns (without placing nozzle), while both the yarn types show little difference in evenness and tensile properties. Hairs are wrapped along the direction of twist in the NozzleRing yarns, It is observed that air pressure, distance of the nozzle from the nip of the front roller, and direction of airflow affects the hairiness. An air pressure of 0.5 kgf/cm² (gauge) is found sufficient to reduce S3 values. Finally, based on the airflow simulation inside the nozzle, a mechanism of hairiness reduction has been proposed. [ABSTRACT FROM AUTHOR]

This experimental work shows how, by means of simple tensile tests, one can estimate low-stress behavior of woven fabrics. [ABSTRACT FROM AUTHOR]

Thread interaction at the warp and weft crossing points of a tensioned fabric is an important aspect of the mechanical properties of the fabric. In this paper, a new approach to measuring changes in thread interaction at the crossing points due to fabric structure and yarn irregularity is discussed. This has been achieved by analyzing thread-pullout behavior from a plain-woven cotton fabric by using an autospectral-density function. It is demonstrated that the nature of the stick-slip motion of the dynamic frictional force of a pulled-out thread is periodic and depends on the fabric construction (warp and weft spacing). The thread-pullout test was also used (on the warp threads only) to investigate the effect of weft-yarn irregularity on the thread-pullout characteristics. It was observed that there is high correlation between warp-pullout force (static and dynamic), the intensity of thread interaction at the crossing points, the strength of fabric in the warp direction, and the weft-yarn irregularity. This new method is important for a quantitative study of the intensity-generating mechanism of thread interactions within the fabric. [ABSTRACT FROM AUTHOR]

The preceding parts of this series detailed a theoretical analysis to predict fabric tensile behaviour, the measurement and mathematical representations of the fibre-orientation angle and curl factor, which are the two principal parameters involved in the treatment, and a complete list of variables essential for computations and procedures to determine their values. This paper presents a comparison of the predicted stress-strain curves, constructed from the computer calculations, and the experimental ones for the nine commercial fabrics studied. After the individual remarks concerning the outcome for each fabric, possible reasons for the discrepancies encountered between the theoretical and experimental curves and the validity of some assumptions made in the analysis are discussed. [ABSTRACT FROM AUTHOR]