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The center of gravity of a vehicle (CG) is a critical parameter in influencing the quality of driveability and safety, such as for preventing rollover accidents. Therefore, it is important to identify a vehicle’s CG in practical situations. In particular, it is strongly desired to make it possible to measure the height of the CG of trucks and trailers freighted with various voluminous and heavy loads on business operation. The technology of Weigh-In-Motion (WIM) is being developed to identify the gross weight of trucks and trailers and detect overload. In this paper, the authors propose a method for the estimation of a vehicle’s CG, especially the height of CG, based on the WIM system. The basic theory is described at first, and the validity is shown by means of basic experiments using a light truck and a motorbike.

Static weight estimation of a vehicle in motion is challenging, especially when the vehicle is accelerating and decelerating. This paper presents a new estimation method for accelerating and decelerating vehicles. This method uses at least two miniature load measurement devices cascaded in traffic lane and consideration of transfer load between the front and rear wheels of a motorbike. Both individual axle load and the gross mass of the motorbike are estimated with accuracy under field conditions.

Accurately and reliably measuring the gross weight and static load of the axles of moving vehicles, especially trucks, is important for preventing road damage and improving traffic safety and monitoring efficiency. This type of vehicle weight measurement is called “weigh-in-motion” (WIM). The conventional purpose of WIM is solely the estimation of the vehicle gross weight. However, WIM is also valuable for estimating the static axle load and the height of the vehicle’s center of gravity, and possibly additional measurements. In this study, a method based on the averaging principle is proposed for signal processing in WIM systems. A preliminary experimental investigation, which involved two types of motorbikes and a light truck as test vehicles, and miniature plate-type measurement devices built by the authors, is presented. The gross weight and the static load of each axle of the vehicles, which traveled at various speeds up to approximately 40 km/h, are estimated with high accuracy.

This study aims to develop an actively deformable space antenna system for radio astronomy around 100GHz. In order to reduce the thermal deformation in active control mechanisms composed of multiple materials, a method to cancel the mismatch of the coefficients of thermal expansion (CTE) is proposed and tested. The CTE mismatch between piezoelements and Super Invar structures is cancelled by adding another metallic part. For effective CTE cancellation, this study clarifies the cause of thermal deformation induced by the preloading mechanisms for a piezoelectric stack actuator. In addition, it shows the effect of the dimension tolerance of the piezoelements is significant, but still manageable by the proposed CTE cancellation method. The effectiveness of proposed method is validated by the use of finite-element analysis, prototyping models, and thermal deformation measurement experiments.

This paper clarifies the mechanism of significantly improved compact storage of membrane space structures where plain-woven textiles are used as the base membrane. Membrane space structures can be multifunctional by attaching various thin-film devices onto their surface; however, the non-negligible thickness of the devices should be accommodated to achieve compact storage. In this study, small scale models made of membranes with dummy thin-film devices are stored to show two significant aspects. Firstly, that textile membranes can be stored more compactly and uniformly than polymer films, because of the movement of layers caused by the flexibility of the textile. Secondly, that the locations of the movement between membrane layers to absorb thickness effect differ depending on the fiber orientation of the textile. [ABSTRACT FROM AUTHOR]

For the foreseeable future, tall building structures will be built taller and more flexible, which means more vulnerable to excitations. As such, there is considerable interest in developing structural control methods to protect against harmful vibrations. However, challenges present themselves for conventional mass damper systems as these tend to primarily utilise lateral motion which becomes very limited as the height of structures increases. This article proposes a novel approach to reduce tall building’s long-period oscillations using mass damper motion in the much larger longitudinal direction. This motion induces Coriolis effect and if manoeuvred properly can be used to effectively reduce vibration of the primary structure. Numerical analysis was done using finite element method. The Shinjuku Mitsui Building was used as a benchmark for the primary structure, which was modelled as a vertical cantilever beam. The results showed the concept to be a viable approach for damping long-period vibrations of flexible structures. Enhancing this effect was also introduced and briefly discussed, using a multiple-degree-of-freedom damper and a constant positive velocity water-flow damper as examples. Further work continues for optimum design of the concept to make it a practical approach for tall buildings. Additionally, investigation into enhancing the damping effect is being done in more detail. This approach provides new possibilities for vibration control of any long-period structure. [ABSTRACT FROM AUTHOR]

This study clarifies the effect of thermal deformation in the reconfigurable space reflector system, through a series of experiments in thermostatic chamber using a prototype of reconfigurable space reflectors. This study then discusses possible countermeasures against precision degradation of such system due to the thermal deformation, exploiting a linkage model and a finite element method model. Though reconfigurable reflector systems have the mismatch in the coefficient of thermal expansion among their structural members, the effect of the mismatch may be minimized by using monometallic mechanism design, and a proper combination of several materials. [ABSTRACT FROM AUTHOR]

This study estimates the effect of creases, or plastic wrinkle lines, on the out-of-plane stiffness of solar sails. A method to simulate the crease effects using reduced-order finite-element (FE) models is proposed, and is applied to a practical solar sail architecture. A detailed crease shape is determined by a geometrically nonlinear FE analysis using a simple model first; the effect of creases is then replaced by beam elements. This method substantially reduces the computational effort required for the FE analysis of a solar sail model. The result suggests the significant impact of creases on membrane’s out-of-plane stiffness when the tension level in the membrane is small. [ABSTRACT FROM AUTHOR]

This paper proposes a method to store a large solar-sail membrane while ensuring repeatability of its stored configuration. Large membranes used as a solar sail should be stored compactly to save the launch volume; in addition, their stored configuration should be sufficiently predictable in order to guarantee reliable deployment in orbit. However, it is difficult to store a large membrane compactly because of the finite thickness of the membrane. This paper demonstrates the feasibility of the proposed “bulging roll-up” method experimentally using 10m-size membranes, and evaluates the repeatability of its stored configuration quantitatively. [ABSTRACT FROM AUTHOR]

Passive dynamic vibration absorbers (DVAs) are often used to suppress the excessive vibration of a large structure due to their simple construction and low maintenance cost compared to other vibration control techniques. A new type of passive DVA consists of two pendulums connected with spring and dashpot element is investigated. This research evaluated the performance of the DVA in reducing the vibration response of a two degree of freedom shear structure. A model for the two DOF vibration system with the absorber is developed. The nominal absorber parameters are calculated using a Genetic Algorithm(GA) procedure. A parametric study is performed to evaluate the effect of each absorber parameter on performance. The simulation results show that the optimum condition for the absorber frequencies and damping ratios is mainly affected by pendulum length, mass, and the damping coefficient of the pendulum's hinge joint. An experimental model validates the theoretical results. The simulation and experimental results show that the proposed technique is able be used as an effective alternative solution for reducing the vibration response of a multi degree of freedom vibration syst [ABSTRACT FROM AUTHOR]