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The coupled, dynamic loads from vehicles travelling on a bridge can cause excessive vibration of the bridge and limit its service life. The coupled vehicle–bridge interaction (VBI) is strongly determined by the properties of the vehicle suspension, the vehicle speed, and the bridge flexibility. A bridge-friendly vehicle is designed to minimize the contact force between the tires and the bridge, enhancing the vehicle’s performance and protecting the bridge from damage by optimizing the vehicle suspension system. In this paper, we investigate the concept of bridge-friendly vehicle by optimally tuning the parameters of the vehicle suspension to mitigate the bridge vibration. The vehicle is modeled with an inerter–spring–damper (ISD) suspension. A time-frozen technique is applied to obtain the time-varying displacement transmissibility functions of the coupled system, and effects of the suspension inerter on the time–frequency characteristics of the transmissibility are discussed. The fixed-point principle is applied to derive the optimal values of the ISD, which are shown to depend only on a priori known structural parameters of the bridge and vehicle parameters. Numerical simulations of the coupled system responses are presented to demonstrate the effectiveness of the tuned ISD in mitigating the vibration of the vehicle and the bridge. Effects of considering the inerter in the suspension model in this tuning problem for bridge-friendliness are also discussed.

Many rheological properties of blood, along with transport properties of blood cells can be captured by means of modeling blood through its main constituents, red blood cells (RBCs) and plasma. In the current work, we present a fully resolved two-dimensional model for blood suspension flow, employing a discrete element model (DEM) for RBCs and coupling it to a lattice Boltzmann method (LBM) fluid solver using the immersed boundary method (IBM). We identify an efficient computationally reduced mesoscopic representation of cells and flow, still able to recover essential physics and physiological phenomena. Our model is found to agree quantitatively with experimental findings. The Fåhræus–Lindqvist effect and shear thinning is recovered, while the thickness of the cell-free layer (CFL) matches the observations. In addition, we investigate the tank-treading frequency of a single RBC in shear flow along with the transition from tumbling to tank-treading, also matching experimental data.

The electrorheological (ER) properties were studied with ternary suspensions containing solid and liquid dispersoids in silicone oil (DMS). The solid dispersoid used was polyether/montmorillonite nanocomposite particles in which polyether molecules were intercalated between the layers of montmorillonite. The liquid dispersoid was urethane-modified polyether prepared from 4,4′-diphenylmethane diisocyanate (MDI) and poly(propylene glycol) (PPG). The steady shear viscosity and dynamic viscoelasticity were measured with a rotating parallel disc rheometer equipped with ER measurement system. The binary and ternary mixtures of these solid and liquid dispersoids with DMS, i.e. composite particle/DMS suspension, polyether/DMS liquid blend, and ternary blend containing both dispersoids, showed an increase of viscosity in response to an electric field (positive ER effect). The ER effect of a ternary suspension containing the particles and polyether liquids was larger than those of binary suspension or blend with one of these dispersoids. The ER effect was found to be improved by combination of the solid and liquid dispersoids, although the recovery time of viscosity after removing the electric field became rather longer, which would be due to the partly irreversible macroscopic aggregation of the dispersoids.

This paper deals with the presentation of a kinetic model for a suspension of identical hard spheres. Considering that the collisions between particles are instantaneous, binary, inelastic and taking the diameter of the spheres into account, a Boltzmann equation for the dispersed phase is proposed. It allows one to obtain the conservation of mass and momentum as well as, for slightly inelastic collisions, an H-theorem which conveys the irreversibility of the evolution. The problem of the boundary conditions for the Boltzmann equation is then introduced. From an anisotropic law of rebound characterizing the inelastic and non-punctual impact of a particle to the wall, a parietal behavior for the first moments of the kinetic equation is deduced.

For an orientation preserving homeomorphism φ of the disk into itself, a suspension of a finite union of periodic orbits P of φ represents a link type in the 3-sphere S³. Let φ be a C¹ diffeomorphism, and p a hyperbolic fixed point of φ with a homoclinic point. If all the homoclinic points for p are transeverse, then for infinitely many n>0, φⁿ induces all link types, that is, for each link type L in S³, there exists a finite union of periodic orbits of φⁿ such that a suspension of of φⁿ represents L.

Let φ:D²→D² be an orientation preserving homeomorphism of the disk into itself, and Φ= {φ_t}_0≤t≤1 an isotopy with φ₀=id_D² and φ₁=φ. Then for a finite union of periodic orbits P of φ, the set is a link in D²×S¹. We say that φ induces all link types (for Φ) if there exists a homeomorphism h of D²×S¹ into a standardly embedded solid torus in the 3-sphere S³ such that any link L in S³ can be realized by a finite union of periodic orbits P_L of φ so that L and are equivalent. We will show that the Smale horseshoe and its second power do not induce all link types, but its third power does induce all link types.

This paper examines the dynamics of a nonlinear semi-active suspension system using a quarter-car model moving over rough road profiles. The bifurcation analysis of the nonlinear dynamical behavior of this system is performed. Codimension-two bifurcation and homoclinic orbits can be discovered in this system. When the external force of a road profile was added to this system as a parameter with a certain range of values, a strange attractor can be found using the numerical simulation. Finally, the Lyapunov exponent is adopted to identify the onset of chaotic motion and verify the bifurcation analysis.

Electrorheological (ER) properties of polyaniline (PAni), pumice and polyaniline/pumice composites (PAPC) were investigated. Polyaniline and PAni/pumice composite were prepared by oxidative polymerization. PAni/pumice particles-based ER suspensions were prepared in silicone oil (SO), and their ER behavior was investigated as a function of shear rate, electric field strength, concentration and temperature. Sedimentation stabilities of suspensions were determined. It has been found that ER activity of all the suspensions increases with increasing electric field strength, concentration and decreasing shear rate. It has shown that the suspensions have a typical shear thinning non-Newtonian viscoelastic behavior. Yield stress of composite suspensions increased linearly with increasing applied electric field strength and with concentrations of the particles. The effect of high temperature on ER activity of pumice/silicone oil systems was also investigated.

A general theory on charges relaxation process in particle-fluid systems is introduced in this article. The method to derive analytical solutions for the charge relaxation equation is illustrated, and some respects for this theory are discussed in detail.

A viscous incompressible fluid with a large number of small axially symmetric solid particles is considered. It is assumed that the particles are identically oriented and under the influence of the fluid they move translationally or rotate around symmetry axis but the direction of their symmetry axes does not change. The asymptotic behavior of small oscillations of the system is studied, when the diameters of particles and distances between the nearest particles are decreased. The equations, describing the homogenized model of the system, are derived. It is shown that the homogenized equations correspond to a non-standard hydrodynamics. Namely, the homogenized stress tensor linearly depends not only on the strain tensor but also on the rotation tensor.

The present work is concerned with the analysis of an axi-symmetric flow of blood through coaxial tubes where the outer tube has an axially symmetric mild stenosis and the inner tube has a balloon which is axi-symmetric in nature. The mild stenosis approximation is used to solve the present problem. The effect of the volume fraction density of the particles, the maximum height attained by the balloon, the radius of the inner tube, which keeps the balloon in position k, and the axial displacement of the balloon have been studied. Flow parameters such as the resistive impedance, the wall shear stress distribution in the stenotic region and its magnitude at the stenosis throat have been computed for different parameters. It is observed that the resistance to flow decreases with increasing values of the axial displacement of the balloon, while the resistance to flow increases with the volume fraction density of the particles, the radius of the inner tube, which keeps the balloon in position k, and the maximum height attained by the balloon. The wall shear stress distribution in the stenotic region possesses a character similar to the resistance to flow with respect to any parameter.

Inactivation of pathogens from environment and inhibition of biofilm formation on various surfaces are important for biosafety, biosecurity and public health. Carbon nanotubes (CNTs) possess antimicrobial effects in addition to their unique optical, electrical, mechanical and thermal properties. This review summarizes the antimicrobial effects of single walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) in suspensions and on CNT contained surfaces. To increase antimicrobial effects, CNT composites containing other antimicrobial reagents are introduced. Also described are the possible antimicrobial mechanisms of CNTs.

Diffuse reflectivity in the longer wavelength region after the absorption edge was studied on the LaTiO₂N nitrided. It was discussed in the viewpoint of particle sizes by use of ball milling and bead milling technique. The diffuse reflectivity after absorption edge of the LaTiO₂N powders got lower in accordance with the reduction of particle sizes. In case of LaTiO₂N aqueous suspension after the bead-milling treatment in which the primary particles were well dispersed, remarkable enhancement of the diffuse reflectivity was observed with decreasing the average particle sizes.

An efficient scheme was developed to analyze head-disk interfaces (HDIs) in hard disk drives. HDIs were studied by decoupling the nanometer scale variations of the air bearings and the micrometer scale changes of the suspensions. The nonlinear variations of the air bearing forces and moments were described with analytical expressions obtained from a surface fitting scheme. Combined with a 3 degree of freedom (DOF) suspension model whose parameters were estimated from a comprehensive finite element model, the historical behaviors of a subambient slider during an unloading process can be obtained in a very short computation period, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.

Introduction: Coronavirus disease 2019 (COVID-19) brought forth an unprecedented suspension of fertility treatment worldwide as part of a reallocation of hospital staff and resources to avoid a collapse in the healthcare system. As a nonessential service, postponement of fertility treatment due to the pandemic has impacted the mental health of infertile patients, which comprise $10\%-15\%$ of the Malaysian population.

Objective: To establish the patient’s perspective on how the COVID-19 pandemic has affected their fertility treatment and to ascertain their psychological status.

Methods: This was a cross-sectional study performed in a single academic center in Malaysia. This study was approved by the Universiti Malaya Medical Centre (UMMC) medical research ethics committee (MEC ID NO: 2021714-10376). Patients and partners who were planned for fertility treatment were approached and asked to answer an anonymous electronic survey between July 16, 2021 and December 17, 2021. All patients requiring fertility treatment were included.

Results: One hundred and sixty-five patients were included, and $66.1\%$ of patients did not agree with the Ministry of Health Malaysia’s recommendation to postpone fertility treatment; $97.6\%$ would want to continue with treatment; $75.8\%$ of patients are concerned about advancing age and $11.5\%$ are concerned about reducing ovarian reserve if their treatment was postponed or suspended. From univariate analysis, mild, moderate, severe, and extremely severe levels of psychological disorders were found in our patients. According to multivariate logistic regression, mild stress was significant among 20–30 years old with $p=0.001$ (OR $1.3^7$, $95\%$ CI $2.2^6-8.0^7$). Patients from this age group also suffer from a significant moderate level of stress with $p=0.001$ (OR $2.7^7$, $95\%$ CI $4.9^6-1.4^8$). Other variables, when analyzed using multivariate analysis, had no significant findings.

Conclusion: Stress related to COVID-19 and concerns about its effect on the fertility rate were found to be significant psychological distress among patients undergoing fertility treatment. Therefore, fertility centers should routinely monitor the mental health of patients and offer them psychological counseling.

An anode-supported micro tube SOFC was developed to increase the cell power density and thermal stability by decreasing diameter of tube. Also, the decreasing diameter of tube was possible the rapid start-up of the micro tube SOFC due to rapid heating at operating temperature. In this paper, we investigate the micro tube SOFC for the rapid start-up. The micro tube SOFC consisted of an extruded Ni/YSZ anode tube with an outside diameter and thickness of approximately 6mm and 2mm, respectively. The quick starting operation of a micro tube SOFC was demonstrated. The cell reached the operating temperature and started generating electricity. It took only 20 second to starting with butane as fuel. The propeller of quick starting demonstrator was operated during 45 minute. During the propeller turning, the output current of micro tube SOFC was on the average 0.4A at 0.2V. Also, we investigate the effect of nano YSZ for the improved performance of micro tube. The good stability of the aqueous nano YSZ suspension was investigated the effect of the pH on the anionic polymer. The surface charge of nano YSZ was reduced as the addition of polyacrylic acid at pH 7.5. This surface charge behavior was well correlated with the dispersion stability of suspension.

Model and simulation study is the starting point for engineering design and development, especially for developing vehicle control systems. This paper presents a methodology to develop models for application of smart struts for vehicle suspension control development. The modeling approach is based on decomposition of the testing data. Per the strut functions, the data is dissected according to both control and physical variables. Then the data sets are characterized to represent different aspects of the strut working behaviors. Next different mathematical equations can be built and optimized to best fit the corresponding data sets, respectively. In this way, the model optimization can be facilitated in comparison to a traditional approach to find out a global optimum set of model parameters for a complicated nonlinear model from a series of testing data. Finally, two struts are introduced as examples for this modeling study: magneto-rheological (MR) dampers and compressible fluid (CF) based struts. The model validation shows that this methodology can truly capture macro-behaviors of these struts.