Experimental and Sensitivity Analysis of DMASP Cantilever Vibration Behavior Based on MCS Theory in the Moist Environment

A Micro-cantilever (MC) and a probe are two main components of the atomic force microscope (AFM). The dimensions of these components are in micro scales while their oscillation amplitude is on a nanometer scale. The present study intended to not only increase the accuracy of the simulation with regard to geometric discontinuities based on the Timoshenko Beam Model using the modified couple stress (MCS) theory but also increase the accuracy of the prediction of a system behavior by considering the effect hysteresis effect into the system vibration equations based on Bouc-Wen Model. Due to the lack of the experimental results for this kind of MCs, this paper is focused on the both experiment and simulation results by utilizing the DMASP micro cantilever. The vibration equations have been discretized based on the differential quadrature (DQ) model and solved using the Newmark algorithm and Laplace transforms in the free and forced vibration modes of AFM piezoelectric MC. The roughness of the surfaces affects the MC vibration behavior in the air medium. Therefore, surface roughness affecting van der Waals force has been considered in the air medium. Furthermore, the simulation results were compared with experimental results by performing experimental tests in the air medium with different moisture content. The experimental tests performed in the free vibration mode included frequency and time response and the forced mode sample surface topography and its effect on the MC vibration amplitude during the sample surface topography in different vibration modes. Moreover, the speed of equation solving was accelerated by performing sensitivity analysis based on the EFAST method as well as investigating the coupling effect of geometric and enforcement parameters on the amplitude and frequency of the MC and eliminating less effective parameters. The comparison of experimental results with theoretical results is indicative of the accuracy of MCS theory in the simulation

Sensitivity Analysis of Coulomb and HK Friction Models in 2D AFM-Based Nano-Manipulation: Sobol Method

Abstract: Nanotechnolog

NANO MANIPULATION WITH RECTANGULAR CANTILEVER OF ATOMIC FORCE MICROSCOPE (AFM) IN A VIRTUAL REALITY ENVIRONMENT

One of the problems of working with AFM in nano environment is lack of simultaneous image feedback. For solving this problem, a virtual reality environment (VR) is designed. For this purpose, a nano manipulation environment is implemented and then, through examining and analyzing the forces existing between probe tips and nanoparticle, the process of nanoparticle driving is added to this environment. In the first step of nano manipulation operations, the dimensions of the base plan as well as the exact place of nanoparticles on that plan needs to be defined so that the user can identify the place of the origin and nanoparticles' destination. The second step in simulation is driving the nanoparticle. In this process, the AFM probe tip starts moving toward nanoparticle with a constant speed of V and after touching it and applying F resultant force from probe tip side on nano particles and increasing up to critical value (F ), it overcomes contract and frictional forces existing between the particle and base plane. In this moment, the probe tip starts moving along with nanoparticle and as a result the nanoparticle is transferred to the pre-determined place by the user. Thus the user may observe the manipulation process

Incorporation of Natural Lithium-Ion Trappers into Graphene Oxide Nanosheets

© 2020 Wiley-VCH GmbH Lithium consumption is estimated to face a considerable rise in the next decade; thus, finding new reproducible lithium resources such as brine deposits and seawater has become a fast-growing research topic. However, Li+ extraction from these resources is challenging due to its low concentration and presence of other monovalent cations exhibiting identical chemical properties. Here, it is discovered that tannic acid (TA) inside graphene oxide (GO) nanochannel acts as natural ion trapper, which possesses lithiophilic elements. The lithium-rich feed is achieved by using the potential-driven TA-GO membrane by excluding lithium ions from other monovalent cations. The results showed that the ion trapping capability of inexpensive TA-GO membrane is Li+ > Na+ > K+ with Li trapping energy of −593 KJ mol−1, respectively, where its trapping efficiency goes into a top rank among their expensive synthetic counterparts. Evaluating the combined effect of three key parameters, including barrier energy, hydration energy, and binding energy illustrates that required energy to transport Li-ion through the membrane is higher than that for other monovalent. This proof-of-concept work opens up an avenue of research for designing a new class of ion-selective membranes, based on the incorporation of naturally low cost available lithiophilic guest molecules into 2D membranes

Reformism, Economic Liberalisation and Popular Mobilisation in Iran

Whereas in other MENA countries the impact of neo-liberal policies has been the subject of intense debate, there are at present few voices that directly analyse or critique its social and political consequences in Iran. This article seeks to address this lacuna by analysing the dynamics of reformism, economic liberalisation and popular mobilisation in Iran. It charts the country’s move from a post-revolutionary populism to a liberalised yet increasingly exclusivist model of politics and compares this to trajectories of economic liberalisation in Egypt. Two distinct outcomes of economic reform are analysed in the first part of the article: Socio-economic exclusion; and the contraction of political rights. In the second half, I investigate the ways successive post-war governments in Iran have packaged neo-liberal reforms, and how their re-imagining of the role of the state has led to differing levels of popular resistance. Finally I argue that under the present administration, political elites increasingly are oriented toward strengthening the state and seeking to limit opposition to their policies. However, the absence of neo-liberal hegemony in Iran means that growing mobilization on socio-economic issues is challenging these policies. The Right in Iranian politics is utilizing this mobilisation to present a populist challenge to the reformists in power

A review of friction models in interacting joints for durability design.

This paper presents a comprehensive review of friction modelling to provide an understanding of design for durability within interacting systems. Friction is a complex phenomenon and occurs at the interface of two components in relative motion. Over the last several decades, the effects of friction and its modelling techniques have been of significant interests in terms of industrial applications. There is however a need to develop a unified mathematical model for friction to inform design for durability within the context of varying operational conditions. Classical dynamic mechanisms model for the design of control systems has not incorporated friction phenomena due to non-linearity behaviour. Therefore, the tribological performance concurrently with the joint dynamics of a manipulator joint applied in hazardous environments needs to be fully analysed. Previously the dynamics and impact models used in mechanical joints with clearance have also been examined. The inclusion of reliability and durability during the design phase is very important for manipulators which are deployed in harsh environmental and operational conditions. The revolute joint is susceptible to failures such as in heavy manipulators these revolute joints can be represented by lubricated conformal sliding surfaces. The presence of pollutants such as debris and corrosive constituents has the potential to alter the contacting surfaces, would in turn affect the performance of revolute joints, and puts both reliability and durability of the systems at greater risks of failure. Key literature is identified and a review on the latest developments of the science of friction modelling is presented here. This review is based on a large volume of knowledge. Gaps in the relevant field have been identified to capitalise on for future developments. Therefore, this review will bring significant benefits to researchers, academics and industrial professionals