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A system has been devised for the fast assembly of pegs in holes using a guiding frame which has four degress of freedom and which is separated from the insertion actuator.

This review discusses various means of locomotion developed in a number of countries and concludes with the description of a mobile robot developed at the Technical University of Torino in Italy.

A pneumatic‐fluidic system has been designed and built, with the purpose to recognize the side orientation of pieces.

Aerostatic porous bearings are important for guide rails and spindles. It is well-known that flow restrictors made of porous materials offer major advantages over conventional restrictors in such bearings, including design and manufacturing, load-carrying capacity, stiffness, damping and dynamic stability. Thus, this work numerically investigates the effect of the arc on a new combined annular-thrust aerostatic porous bearing.

The static characteristics of an annular-thrust aerostatic porous bearing were studied using a fast finite element scheme. The pressure distribution, radial load and thrust load were analyzed as functions of the arc, permeability and eccentricity.

The results reveal that the radial load achieves maximal values at an optimal arc value between 200 and 300, and the thrust load increases monotonically with increasing arc.

This work developed a new combined annular-thrust aerostatic porous bearing to investigate the effect of arc on the annular-thrust aerostatic porous bearings to increase the load-carrying capacity.

The purpose of this paper is to present a novel numerical approach to analyze the static performance of aerostatic thrust bearings by adopting a general finite element method calculation program.

The characteristics of a gas film are described by the Reynolds equation and the pressure distribution is solved using the finite element method. A root iterative method is proposed to meet the requirement of the mass-conservation law because multiple pocketed orifice-type restrictors are treated as a series of special boundary conditions.

The static performance of a rotary table using aerostatic thrust bearings, including load carrying capacity and stiffness, can be predicted by the method; moreover, it can be further confirmed through experiments on the designed rotary table.

The method combining the finite element and root iterative methods is highly accurate and has a low time-cost for analyzing aerostatic thrust bearings with multiple pocketed orifice-type restrictors.

Surgical gowns should be designed and produced using special techniques to provide barrier properties against potential risks during surgery and healthcare procedures. Ultrasonic welding is one of these methods used to produce surgical gowns with determined barrier properties. The purpose of this paper is to analyse bond strength and permeability properties of ultrasonically welded nonwoven fabrics and compare them with traditional sewing techniques.

In this study, ultrasonic welding of nonwovens was performed to demonstrate its use as an assembly method. Performance requirements in the design of surgical gowns were determined. Fabric strengths and bond strengths of ultrasonic-welded and traditionally sewn fabrics were analysed. The performance properties, i.e., bond strength, air and water resistance of the fabrics and the joints obtained by ultrasonic and classical sewing methods were studied.

As a result, it was found that ultrasonic welding technique is a suitable method for joining layers in surgical gown production bringing the advantages of high water resistance together with acceptable bond strength.

The current study focuses on the use of ultrasonic welding of nonwovens used for disposable protective surgical gowns. Ultrasound welding technique was presented as an alternative to classic assembly methods and ultrasonic welding technology was applied to different fabric combinations simulating different layers in different joining sections of a surgical gown.

The purpose of this paper is to describe a methodology for characterization of the robot environment to help solve such problem as designing an optimal agricultural robot for a specific agricultural task.

Defining and characterizing a task is a crucial step in the optimization of a task-specific robot. It is especially difficult in the agricultural domain because of the complexity and unstructured nature of the environment. In this research, trees are modeled from orchards and are used as the robot working environment, the geometrical features of an agricultural task are investigated and a method for designing an optimal agricultural robot is developed. Using this method, a simplified characteristic environment, representing the actual environment, is developed and used.

Case studies showing that the optimal robot, which is designed based on the characteristic environment, is similar to the optimal robot, which is designed based on the actual environment (less than 4 per cent error), is presented, while the optimization run time is significantly shorter (up to 22 times) when using the characteristic environment.

This paper proposes a new concept for solving the robot task-based optimization by the analysis of the task environment and characterizing it by a simpler artificial task environment. The methodology decreases the time of the optimal robot design, allowing to take into account more details in an acceptable time.

The misalignment is generally inevitable in the process of machining and assembly of rotor systems with gas foil bearings, but the exploration on this phenomenon is relatively less. Therefore, the purpose of this paper is to carry out the thermo-elastohydrodynamic analysis of the foil bearing with misalignment, especially the inhomogeneous foil bearing.

The rotor is allowed to misalign in two non-rotating directions. Then the static and dynamic performance of the inhomogeneous foil bearing is studied. The thermal-elastohydrodynamic analysis is realized by combining the Reynolds equation, foil deformation equation and energy equation. The small perturbation method is used to calculate the dynamic coefficients, then the critical whirl ratio is obtained.

The gas pressure, film thickness and temperature distribution distort when the misalignment appears. The rotor misalignment can improve the loading capacity but rise the gas temperature at the same time. Furthermore, the rotor misalignment can affect the critical whirl ratio which demonstrates that it is necessary to analyze the misalignment before the rotordynamic design.

The value of this paper is the exploration of the thermo-elastohydrodynamic performance of the inhomogeneous foil bearing with misalignment, the analysis procedure and the corresponding results are valuable for the design of turbo system with gas foil bearings.

The normal operation of a rotor system is generally vulnerable to misalignment between gas foil bearing (GFB) and rotor. However, most theoretical and experimental researches about the characteristics of GFBs have ignored this phenomenon. Therefore, the main purpose of this paper is to evaluate the static and dynamic performance of GFBs considering misalignment.

The shaft is allowed to misalign in two directions. Then the variations of bearing load, friction force, restoring moment, stiffness and damping coefficients are thoroughly explored. The hydrodynamic pressure on the gas film is modeled with compressible Reynolds equation, and the deformation of the flexible bearing is calculated with finite element method. Small perturbation method is used to obtain the displacement and moment dynamic coefficients.

The film thickness and pressure distribution distort when misalignments appear. The inclination of GFBs can enhance the restoring moment to withstand the imposed misalignment. Furthermore, the simulation phenomenon demonstrates the misalignment around load direction should be avoided as much as possible, while a small value misalignment around another direction is allowed.

The value of this paper is the exploration of the influence of misalignments on the static and dynamic performance of the Generation II journal GFB.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0418/

Oil-free heat pumps that use the system refrigerant gases as lubricants are preferred for thermal management in future space applications. This study aims to numerically and experimentally investigate the static performance of externally pressurized thrust bearings lubricated with refrigerant gases.

The refrigerant gases R22, R410A and CO₂ were chosen as the research objects, while N₂ was used for comparison. Computational fluid dynamics was used to solve the full 3 D Navier–Stokes equations to determine the load capacity, static stiffness and static pressure distribution in the bearing film. The numerical results were experimentally verified.

The results showed that the refrigerant-gas-lubricated thrust bearings had a lower load capacity than the N2-lubricated bearings, but they presented a higher static stiffness when the bearing clearance was less than 9 µm. Compared with the N2-lubricated bearings, the optimal static stiffness of the R22- and CO2-lubricated bearings increased by more than 46% and more than 21%, respectively. The numerical and experimental results indicate that a small bearing clearance would be preferable when designing externally pressurized gas thrust bearings lubricated with the working medium of heat pump systems for space applications.

The findings of this study can serve as a basis for the further investigation of refrigerant gases as lubricants in heat pump systems, as well as for the future design of such gas bearings in heat pump systems for space applications.