Nanoobject mass measurement using the node displacement of the second mode of the nanomechanical resonator

This work suggests a new approach to weighting the nanoscale objects placed at the tip of cantilever vibrating inside the camera of scanning electron microscope. In contrast to traditional approach to mass determination, we suggest tracing the shift of the node of the second vibration mode as an alternative to frequency shift measurement. We demonstrate the applicability of our approach to carbon nanowhisker cantilevers grown on tungsten needles by focused electron beam induced deposition. We compare experimentally the performance of the suggested approach with the traditional frequency shift-based method.

Unmanned Vehicles’ Placement Optimisation for Internet of Things and Internet of Unmanned Vehicles

Currently, the use of unmanned vehicles, such as drones, boats and ships, in monitoring tasks where human presence is difficult or even impossible raises several issues. Continuous efforts to improve the autonomy of such vehicles have not solved all aspects of this issue. In an Internet of Unmanned Vehicles (IoUV) environment, the idea of replacing the static wireless infrastructure and reusing the mobile monitoring nodes in different conditions would converge to a dynamic solution to assure data collection in areas where there is no infrastructure that ensures Internet access. The current paper fills a significant gap, proposing an algorithm that optimises the positions of unmanned vehicles such that an ad hoc network is deployed to serve specific wireless sensor networks that have no other Internet connectivity (hilly/mountainous areas, Danube Delta) and must be connected to an Internet of Things (IoT) ecosystem. The algorithm determines the optimum positions of UV nodes that decrease the path losses below the link budget threshold with minimum UV node displacement compared to their initial coordinates. The algorithm was tested in a rural scenario and 3rd Generation Partnership Project (3GPP), free space and two-ray propagation models. The paper proposes another type of network, a Flying and Surface Ad Hoc Network (FSANET), a concept which implies collaboration and coexistence between unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs) and several use cases that motivate the need for such a network.

Dynamic Response Analyses of Plastic Greenhouse Structure considering Fluctuating Wind Load

Wind load is one of the main factors of plastic greenhouse collapse. To solve the dynamic response problem of greenhouses under wind load and determine the dangerous section of a skeleton structure, the investigated lump method is presented for the dynamic response analysis of a plastic greenhouse, considering pulsating wind on the basis of Timoshenko beam theory. First, the investigated lump is designed according to the Timoshenko beam microbody concept. On the basis of Timoshenko beam theory, the governing equations of the skeleton structure of the greenhouse are derived, and the realization process of the algorithm is also provided. Second, the accuracy and effectiveness of the proposed numerical method are verified by an example in which the bending wave of a variable cross section beam with free ends propagates. Finally, the dynamic response of the steel skeletons of plastic greenhouses is analyzed under the effect of the simulation wind speed, and the spatial distribution of the maximum node displacement and the section maximum stress of the steel skeleton are obtained. Computational results show that the displacement peak is near the top of the plastic greenhouse. The most dangerous section of the top chord in the steel skeleton is near the leeward bottom, which has a maximum stress of 219.4 MPa, and the most dangerous section of the bottom chord is near the 1 m height on the leeward side of the plastic greenhouse, which has a maximum stress of 248.5 MPa. Bending stress is the main factor of the rapid increase of stress at the bottom of the skeleton. The maximum node displacement and cross-sectional stress caused by fluctuating wind loads are higher than those caused by average wind loads. The fluctuating wind load should be considered in the wind-induced response analyses of plastic greenhouses.

IWSHM 2019: Perturbation-based Bayesian damage identification using responses at vibration nodes

One important topic for structural health monitoring is to achieve accurate damage detection with a small number of noisy sensors and without the requirement of a high-fidelity finite element model. This article adopts the Bayesian probabilistic approach combined with a perturbation model using responses at a few vibration nodes for damage monitoring. First, the node displacement, or the response at vibration node, is adopted in this study for real-time damage assessment with a relatively small number of sensors. Then, the construction method of the node displacement response curves based on the perturbation model is proposed to replace the expensive finite element model. After that, a Bayesian framework integrated the node displacement measurement and the response curves are adopted to acquire the probability distribution of the damage parameter. In this article, the accuracy of the node displacement–based Bayesian framework with the perturbation method is evaluated. The proposed method is applied to a supporting structure of a sailplane under different noise levels.

A Statistical Method for Area Coverage Estimation and Loss Probability Analysis on Mobile Sensor Networks

Sensor networks are formed by fixed or mobile sensor nodes and their functions are to capture the events that occur within a certain area and then relay to a central node. Normally, sensor nodes are not able to transmit or receive information over long distances due to the need to use less energy and thus extend their useful life. Therefore, the number of sensor nodes in a given area directly influences the coverage of this area and the ability of information to be relayed by several sensors to the central node. If there are many missed messages, the application will have its performance compromised. In this paper, we use a statistical method based on Monte Carlo approach to estimate the probability of message loss and area coverage. The position and proper motion of the sensors are randomly chosen and from that we estimate how many nodes can communicate with the central node directly or through another sensor working as relay. The free variables in our analysis are node density, node displacement velocity, and sensor quantity. The results obtained are compared analytically with simple cases in order to validate the results obtained by the simulations performed.

Experimental Study on Bearing Capacity of Reinforced Steel Tubular Scaffold under Uniform Loads

Five groups of tests were designed to analyze the influence of node types (fastener connection and mortise-and-tenon joint) and reinforcement modes of top horizontal cross rods (weak truss and stiffening truss) on the bearing capacity of the steel tubular scaffold under vertical uniform loads. Loading phenomenon, bearing capacity, failure mode, displacement at key positions, and strain development characteristics during tests were analyzed. The following conclusions were drawn: (1) The fastener scaffold reinforced by a top truss showed the highest bearing capacity and high material utilization. (2) The fastener scaffold reinforced by a top weak truss increased the bearing capacity and caused coordinated deformation of the top horizontal force rods. (3) The node displacement of the mortise-and-tenon scaffold was smaller than that of the fastener joint, whereas its bearing capacity was higher. (4) Vertical diagonal bracing can slightly increase the bearing capacity of the mortise-and-tenon scaffold but can also constrain the deformation of the vertical rods and change the failure mode.

Application of Seismic Resisting Systems for Building Construction in Malaysia

Over the centuries, there has been a lot of earthquakes occur due to sudden changes in the surface of the earth. This phenomenon has caused property destruction, a large number of deaths and damage to buildings. This situation has become a concern by experts, especially engineers around the world since the damage of the building caused huge losses as well as contributing to the loss of life due to burial and so forth. Therefore, this study is conducted to compare the changes of node displacement that occur in each designed buildings caused by the seismic load applied and to determine the best design system that has the smallest amount of node displacement changes during the quake. In this study, three types of model that consist of base frame, shear wall and braced frame are designed using STAAD Pro Software to obtain their displacement reading. Important data such as seismic parameters and load cases which is Zone factor: 0.24, Response reduction factor: 5, Importance factor: 1.5, Structure type: Concrete, Damping: 0.05, Foundation soil type: Medium, Dead load intensity at all floor levels: 6kN/m2 , Live load for roof: 1.5kN/m2 and Live load for other floors: 3kN/m2 are inserted. The strength of resistance toward seismic load between the three models can be evaluated through the displacement occurs in the nodes in every model.

Numerical modeling of space umbrella-type mesh reflector

This paper describes numerical modeling of space umbrella-type mesh reflector. The modeling includes two stages. The first stage embraces the calculation of the shape of cable elements for reflector frontal (rear) nets by the nonlinear force density method. The second stage involves the design of the reflector finite-element model based on the calculated nets. After this, the node displacement and prestress boundary conditions are imposed to determine a node displacement field.