Development of multi-mode vibration damping device using mass spheres embedded in cuboid viscoelastic material allowing external shape change

The flow rate significantly influences the leukocyte depletion rate during prestorage in-line filtration of platelet concentrates

High strain fatigue of 20Cr/25Ni/Nb steel at 1025 K Part II: Total endurances

In this paper, the authors propose, investigate, and discuss a concept of novel type of deployable helium-filled aerostat as a low-cost mean of transport. Internal construction of the aerostat is based on ultra-light tensegrity structure equipped with prestressed tensioned elements of controllable lengths. Such tensegrity structure allows for adaptive morphing of the aerostat understood as simultaneous controllable modifications of aerostat volume and shape during the flight. The controlled volume changes enable influencing buoyancy force and obtaining desired vertical motion during the ascending and descending process. In turn, external shape changes allow for lowering the aerodynamic drag and energy usage needed to uphold stable horizontal position or maintain the desired flight path. Moreover, such internal structure allows for convenient storage, transportation and deployment of the aerostat construction on the ground or in required point at the atmosphere. The article presents an analysis of the exemplary operational mission of the aerostat. The authors introduce the mechanical model capturing interaction of the internal tensegrity structure and aerostat envelope based on the finite-element method, as well as dynamic model allowing for simulation of the aerostat’s vertical and horizontal motion influenced by buoyancy and drag forces. Both these models are used to positively verify the feasibility of the proposed concept of deployable tensegrity-based aerostat with adaptive morphing and its efficiency in realization of the assumed flight mission.

This paper reports a study that aims at the development of a design procedure for supporting headlamp design process as needed in the development of passenger cars. Headlamps can introduce an important styling attribute to a vehicle especially for passenger cars. The shape of headlamp has to be integral with the external shape changes, which necessitates frequent redesign of headlamps while making changes on the body by the stylist or designer. The exterior of headlamp lens/cover has to be visually continuous to the external profile which is an assemblage of three or more surfaces. This work proposes a design methodology for the design of headlamp lens enabling the generation of headlamp exterior surface from the input containing information about the associated external surfaces. In addition, surface interrogation with reflection lines and highlight lines for global evaluation has been carried out. A method to determine principal curvatures at any point on the surface for local evaluation of surface is also proposed.

The article presents the review of the main methods of restoration and repair of machine parts: mechanical and bench work, welding, surfacing, metal coating, chrome plating, nickel plating, steeling (iron plating), bonding, hardening the surface of parts and restoring their shape under pressure. The areas of application of each method, its advantages and disadvantages are noted. Welding and surfacing are used to restore more than half of all repaired car parts. With the help of welding, cracks and fractures on the frame and platform are repaired, patches, various overlays and reinforcing gussets are put, and the crankcases of the units are restored. Damaged or worn threads on stub axles and other parts are restored by welding, followed by cutting a new thread. The internal threads are restored in the same way. Restoration of parts by surfacing consists in surfacing the worn working surfaces in such a way that they can be processed to the nominal or repair dimensions. When repairing cars, automatic and semi-automatic surfacing and welding under a layer of flux or in a carbon dioxide environment are used. Damaged and worn parts can be repaired by pressure. This method is based on the use of the ductility of metals. The parts are restored to their nominal dimensions with the help of special devices, by moving a part of the metal from non-working areas of the part to its worn surfaces. When restoring parts by pressure, not only their external shape changes, but also the structure and mechanical properties of the metal. Plastics are used to restore worn parts when repairing metal-cutting machines. As an adhesive, plastics are widely used for bonding broken parts, as well as for obtaining a fixed connection of parts made of metallic and non-metallic materials. When repairing metal-cutting machines, the most widely used plastics are textolite, wood laminated plastics and fast-hardening plastic — styracryl.

An in-situ study of the dissolution of γ-zirconium hydride in zirconium

<div class="section abstract"><div class="htmlview paragraph">Aerodynamic analysis is a primary requirement in the development of electric scooters to predict the impact of air flow around the vehicle on critical performance parameters including the overall range, vehicle stability due to wind loads, air cooling of electric motor and battery. Any new design of vehicle requires an aerodynamic evaluation to estimate the variations in drag forces with speed. It is prohibitively expensive and time consuming to perform full-scale model wind tunnel tests on each variant of the vehicle configuration for wide range of driving scenarios. Physics-based 3D simulation is the preferred approach in the present context and the use of Computational Fluid Dynamics (CFD) for such cases has been well understood and established. Although only the external shape changes make a difference to external aerodynamics, sometimes even a small variation in shape could trigger unwanted flow behavior leading to large drag forces, or enhance the vehicle performance by reducing the drag, with less aggressive design changes. In the present work, we study aerodynamics of world’s first Compact Logistics Vehicle (CLV) – a purpose-built electric cargo scooter that can accommodate a rider and a pillion along with a significant amount of dedicated cargo space. We already established the methodology and best practice for a variant of the present vehicle which could accommodate only the rider and have implemented the same in the current study. A total of 15 different scenarios including three different vehicle and rider combinations across a range of velocities (6 m/s or 21.6 km/h, 8 m/s or 28.8 km/h, 11 m/s or 39.6 km/h, 16 m/s or 57.6 km/h and 22 m/s or 79.2 km/h), have been studied, by placing the vehicle in a virtual wind tunnel and simulating the velocity and pressure distribution, and most importantly total drag force for each scenario. The three cases comprise the stand-alone vehicle, vehicle with the rider, and vehicle including the rider and the passenger (pillion). The result of this study indicates only a slight variation in the drag due to the presence of a rider along with the passenger (pillion). We are able to capture the aerodynamic characteristics of the recirculation zones in all of these cases. In addition to the variations in the inlet velocities, we also studied the effect of the turbulence intensities (5%, 10%, and 20%) on the over-all drag coefficient.</div></div>

A large contribution to the aerodynamic drag of a vehicle arises from the failure to fully recover pressure in the wake region, especially on squareback configurations. A degree of base pressure recovery can be achieved through careful shape optimisation, but the freedom of an automotive aerodynamicist to implement significant shape changes is limited by a variety of additional factors such styling, ergonomics and loading capacity. Active flow control technologies present the potential to create flow field modifications without the need for external shape changes and have received much attention in previous years within the aeronautical industry and, more recently, within the automotive industry. In this work the influence of steady blowing applied at a variety of angles on the roof trailing edge of a simplified ¼ scale squareback style vehicle has been investigated. Hot-wire anemometry, force balance measurements, surface pressure measurements and PIV have been used to investigate the effects of the steady blowing on the vehicle wake structures and the resulting body forces. The energy consumption of the steady jet is calculated and is used to deduce an aerodynamic drag power change. Results show that overall gains can be achieved; however, the large mass flow rate required restricts the applicability of the technique to road vehicles. Means by which the mass flow rate requirements of the jet may be reduced are discussed and suggestions for further work put forward.

The role of platelets in hemostasis and thrombosis has been well established since Eberth's and Schimmelbusch's pioneering intravital microscopic experiments. A century ago the distinct features of the circulating "smooth disc" and the activated "spiny sphere" were described. Since then the underlying cell-biological processes transforming a harmless floating platelet into a sticky corpuscle, ready to release its stores of thrombogenic and atherogenic substances have been unveiled. However, its life-threatening capabilities have evolved from the necessity of preventing equally dangerous blood losses from a pressurized circulation system. As circulation depends on the liquid state of blood, the platelets and the molecules of the plasmatic coagulation system must circulate in an inactive state, to become activated at the site of "demand" to transform the liquid into a solid hemostatic plug. As in nucleated cells the plasma membrane, made up of a phospholipid bilayer with integrated glycoproteins, is the structure signalling environmental information to the platelet interior. Many of the receptors for stimulatory or inhibitory mediators elicit a cell-biological response via G-proteins and subsequent Ca2+ mobilization by IP3, or stimulation/inhibition of adenylate cyclase followed by changes in cytoplasmic levels of cyclic AMP. The supposed intracellular Ca2+ store of the platelets, the dense tubular system, also appears as the site of Ca2(+)-activated prostaglandin synthesis. Raised cytoplasmic Ca2+ levels promote the polymerization of G-actin to F-actin involved in the extension of pseudopodia in the course of "external shape change." Ca2(+)-activated myosin light-chain kinase phosphorylates myosin which becomes associated with F-actin, with the resulting acto-myosin complex providing the contractile force for "internal shape change," i.e., the centralization of organelles and for clot retraction later in hemostasis. More than by the three-dimensional actin cytoskeleton proper, the discoid shape typical of the nonstimulated platelet appears to be secured by a two-dimensional membrane skeleton of actin filaments anchored to membrane glycoproteins via actin-binding protein or spectrin and ankyrin. Although the microtubule coil has been confirmed as the main determinant of the mechanical stiffness of the platelet with biophysical techniques, its hitherto assumed role for the maintenance of the disc shape no longer appears tenable. The morphological phenomenon of the shape change comprises an alteration of membrane glycoproteins resulting in binding of "adhesive" molecules like fibrinogen.(ABSTRACT TRUNCATED AT 400 WORDS)

‡Algorithms for rapid generation of moderate-fidelity structural finite element models of air vehicle structures to allow more accurate weight estimation earlier in the vehicle design process have been developed. Application of these algorithms should help to rapidly assess and generate many structural layouts before the start of the preliminary design phase and reduce weight penalties imposed when actual structure weights exceed those estimated during conceptual design. By defining the structural topology in a fully parametric manner, the structure can be mapped to arbitrary vehicle configurations being considered during conceptual design optimization. Recent enhancements to this approach include the porting of the algorithms to a platform-independent software language Python, and modifications to specifically consider morphing aircraft-type configurations. Two sample cases which illustrate these recent developments are presented. I. Introduction HE application of multidisciplinary optimization to aero-structural design of flight vehicle structures has been a topic of considerable attention in recent years. Computational mesh generation has advanced considerably and has been used to allow parametric aerodynamic design of vehicle shapes to be considered in this optimization process. However, the structural layout design has not been typically treated with the same level of detail. In most cases, the structural layout is fixed and only a structural sizing optimization is performed. In the few instances where the layout is considered as a variable itself, the model chosen is usually overly simplistic, not representative of actual vehicle designs, and suspect from an accuracy perspective. Aircraft manufacturers have very accurate structural models of existing vehicles, but these models take literally months to generate and are not suitable for rapid consideration of candidate designs. Thus, there is a need for a methodology to create structural models of at least intermediate fidelity while incorporating the ability to generate these models automatically based on a parametric description of the structural layout. This will facilitate the application of these models to rapid generation and assessment of candidate external vehicle shapes. As a first step towards developing this automatic model generation capability, an abstraction of the aircraft structural elements and their layout was constructed so that models could be created quickly for a given structural layout regardless of changes in external shape. This abstraction was based on a thorough study of structural design trends in modern aircraft of various types 1 . Based on this abstraction, some initial algorithms to allow mapping of parametric structural topologies to arbitrary wing shapes were developed. These algorithms allow a structural designer to specify a layout in parametric terms, specifying locations in percentages of span and chord rather than actual dimensions. This specification is independent of the aircraft geometry so that upon making a change to the

This paper develops a mathematical model and a structured procedure to optimize the internal structure (relative sizes, spacings) and external shape (aspect ratios) of a unit PEM fuel cell so that net power is maximized. The optimization of flow geometry is conducted for the smallest (elemental) level of a fuel cell stack, i.e., the unit PEM fuel cell, which is modeled as a unidirectional flow system. The polarization curve, total and net power, and efficiency are obtained as functions of temperature, pressure, geometry and operating parameters. The optimization is subjected to fixed total volume. There are two levels of optimization: (i) the internal structure, which basically accounts for the relative thicknesses of two reaction and diffusion layers and the membrane space, and (ii) the external shape, which accounts for the external aspect ratios of a square section plate that contains all unit PEM fuel cell components. The available volume is distributed optimally through the system so that the net power is maximized. Temperature and pressure gradients play important roles, especially as the fuel and oxidant flow paths increase. Numerical results show that the optimized internal structure is “robust” with respect to changes in external shape. The optimized internal structure and external shape are results of the optimal balance between electrical power output and pumping power required to supply fuel and oxidant to the fuel cell through the gas channels. Directions for future improvements at the PEM fuel cell stack level in constructal geometric optimization are discussed.

Constructal flow structure for a PEM fuel cell

Effects of trunk deformation on trunk center of mass mechanical energy estimates in the moving horse, Equus caballus

External human-machine interfaces (eHMIs) are shown to support Automated Vehicles (AVs) in interacting with vulnerable road users such as pedestrians. Typically, eHMI concepts are light- or sound-based designs that communicate the AV’s intention with abstract visualizations, which are unfamiliar, not fully intuitive, and require learning. In the natural world, animals are shown to communicate their intention or disposition with a variety of visible reactions, using posture, gesture, or other means, which have implicit meaning by association with centuries of evolution. We explore the design space of biomimicry-inspired communication between AVs and pedestrians using external Shape-Changing (eSC) interfaces. We created six distinct concepts of eHMIs that employ external shape change and evaluated them in a focus group. Results show that zoomorphic, shape-changing-based eHMI concepts are promising in achieving intuitive communication about an AV’s intention in traffic. This may help in reducing the learning effort associated with abstract eHMIs, and ease the integration of AVs.

： In order to reduce the noise and oscillation, it is consider a matter in all aspects about the noise stem from accumulator and the character istic of transmission, Transformation of outside shape has change of noise occurrence at transmission process. Therefore, performed sound numerical analysis and conducted an experiment to examine the birthplace of accumulator's external shape change. In a sound numerical analysis, we can fond out transmission loss between inlet and o utlet's sound pressure. In an experiment, we can make out transmission loss by sound wave separation theory through drawing sound pressure inlet and outlet. Key words ：Accumulator(어큐뮬레이터), Deep drawing(디프드로잉), Polygon deep drawing(다각형 디프드로잉), Redrawing(재드로잉), Transmission loss(투과손실) †교신저자(부산대학교 기계공학부, E-mail:kimyho@pusan.ac.kr, Tel:051-510-2322) * 부산대학교 대학원 기계공학부 ** 부산대학교 대학원 기계공학부*** 엔알텍(주) 대표이사, 김해 기호설명 Z r : 방사임피던스(radiation impedance) p : 음압(sound pressure), Pa v : 매질의 속도(particle velocity), m/s