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In this paper, computer‐aided design optimization approach for hydrostatic bearings is presented. The optimization problem is formulated in multicriteria strategy. The power loss and the temperature rise of oil are considered as performance measures for optimal hydrostatic bearing design. Optimization results indicate the effectiveness of the proposed combined approach which has advantages over the single criteria optimization. Sample results are presented to verify the proposed approach.

Water vapor trapped in the boundary layer between a person and the clothing creates discomfort and other unpleasant sensations. When that water vapor is prevented from leaving the clothing by external vapor barriers or impermeable layers, those psychophysical states are further exacerbated. One situation where that can be problematic is in office workplaces, and the seats that workers use for many hours every day. This study aims to evaluate the impact of different fabrics that are used for seat cover on water vapor retention.

The authors' method determines the behavior of contact surface humidity with a 50 kg sandbag on the seat to mimic the deformation of the seat materials due to the seated person's weight. Thus, the maximum increase in relative humidity (RH) after humidification of the seat surface (ΔRH-max), the time required to reach the maximum value of humidity (t-max) and the time constant (TC) after humidity starts to fall were derived.

Of the three different seat covers tested, the ΔRH-max of the wool were 7.3–8.8%, compared to 27.0–29.0% of the polyvinyl chloride (PVC), indicating more moisture absorption and transmission of the wool. The TC of the acrylic cover was 224–384 min compared to the 483–558 min of the PVC, which indicated a quick drying out feature of the acrylic.

The ΔRH-max, t-max and TC were all significantly correlated with the RH at the back thigh skin surface of the actual human participants.

Fretting wear takes place when two contacting solid surfaces are subjected to relatively small amplitude oscillatory motion in the order of a few microns. The purpose of this paper is the design and manufacture of a fretting wear test rig that can analyze fretting wear on journal bearings.

This study included the manufacturing and operating principles of the test rig. In the test rig, the shaft was fixed and vibrational motion was given to the bearing housing. Vibration motion the amplitude of which could be adjusted was used on the test rig. The vibration motion was applied to a two-piece journal bearing on a fixed shaft supported from both ends.

Vibration amplitude was provided by a micro vibration engine (motor) to be under 100 μm.

Also, scanning electron microscopy, energy dispersive X-ray and X-ray diffraction analyses of the samples were investigated.

Contemporary management and strategy mean optimization of ingredient factors such as human factors, systems, operations and equipment. With system approach in management and strategy, human risk factor as input has considerable potential to change results as airworthiness in aviation management. The managers of aviation business also optimize their functions to act safe while making contribution to development in triple of sustainability as economic development and its sustainability; social development and its sustainability; and environmental development and its sustainability. Corporate sustainability can be accomplished via supporting workforce which is the human risk factor. To support (empowerment) workforce, researchers should identify human risk or error factors which are important to this research. The purpose of this study is to suggest holistic framework for working environment system of aircraft maintenance technicians (AMTs) within two respects such as human performance (ergonomics) and corporate performance (sustainability). The secondary purpose of this system is to develop human risk taxonomy by determining the factors affecting both human and work by taking ergonomic aspects in aviation.

In this study, a taxonomy of human risk factors for AMTs is developed. These human factors divided into groups and subfactors are obtained from an extensive literature review and experts’ opinions in the field of human performance in aviation. Taxonomy developed will be useful to both sharing and using corporate sources in sustainable way.

Human risk factors can be considered or accepted as factors that cause human error. This may result in the optimum way to managing human risk factor via minimizing human-based error. Personality, hazardous attitudes, individual characteristics, physical/psychological condition of AMTs and corporate social responsibility factors are human-related risk variables in this study. The risks and error can be reduced by recognizing these factors and revealing their relation to ergonomic design.

The results of this study are intended to constitute a guide for managers to manage risk factors and to take corrective and preventive actions for their maintenance operations. It is believed that this study is highly important for the aviation sector in terms of raising awareness or providing awareness for similar practices. As taxonomy of the risk factors contributes to the managing human error, corrective actions related to these factors must be taken by managers.

Aircraft maintenance technician (AMT) is the most critical profession in the aircraft maintenance system. The tasks of a licensed AMT require expertise and involve repetitive physical tasks such as tightening or loosening aircraft parts, carrying or removing parts during long working hours under time pressure and day/night shifts. This study aims to attract attention to the difficult working conditions of AMTs and identify the body parts that are at risk of musculoskeletal disorder (MSD).

A questionnaire is developed by the authors to gather demographic information, use of hand tools, equipment, use of fall protection, manual material handling (lifting, pushing, pulling), load weight, environmental factors, and MSD discomfort level perceptions. The questionnaire is applied to 150 AMTs during six months period, and the obtained data are analyzed by sequential ordinal logistic regression (OLR) models.

The ORL results confirm that the use of equipment (lift platform, scissors lift), safety belt attached to the platform, manual material handling, environmental factors (humidity, vibration and illumination) and resting periods have a significant effect on MSD risks. On the contrary, age, experience level, use of small hand tools, temperature and noise are not identified as statistically significant.

The study is original for it considers the working conditions and perceived discomfort levels of AMTs. A questionnaire is introduced to assess the consequences of the use of tools, equipment, fall protection equipment, environmental conditions and work organization on various body parts (neck, shoulder, elbow, back, lower back, wrist-hand, hip, knee, and ankle-feet), and strain level is identified. The study contributes to the theoretical aircraft maintenance literature and managers in practice.

This research has the potential to contribute to the understanding of the sustainable ground handling operations framework. Ramp operations as the main system of ground handling include critical services for aircraft/airlines. The purpose of this study is to identify the risk factors in ramp operations for all related stakeholders’ awareness to enhance flight safety. Classifying risk factors, the four main performance fields under risk taxonomy is determined. Thus, managers may allocate resources effectively to handle related threats for corporate sustainability.

New taxonomy with human performance value indicators, which sources from the environment is developed. New developed taxonomy is entitled as “environmental value approach,” which represents environmental value-based approach. The developed new risk factors taxonomy is divided into groups such as ramp personnel, organizational, sustainability-based risk factors: triple view and ergonomics obtained from an extensive literature review and experts’ opinions in the field of human performance.

The findings of this research show that managers need a risk management-oriented approach to manage the human factor affecting performance and sustainability. The newly developed taxonomy offers not only identifying the sources of unsafe operational risk factors but also using as a decision-support tool to manage risks for achieving their sustainability goals. When managerial decisions are made according to risk taxonomy and managing these risks, then corporate performance and individual performance may improve.

The new taxonomy presents the performance-based management of the human factor with a holistic and systematic risk management-based approach. There is no risk taxonomy study designed considering ramp operations and sustainability-based human factor performance.

The purpose of this paper is to improve static/dynamic characteristics of active-controlled hydrostatic journal bearing by using fractional order control techniques and optimizing algorithms.

Active lubrication has ability to overcome the unpredictable harsh environmental conditions which often lead to failure of capillary controlled traditional hydrostatic journal bearing. The research develops a mathematical model for a servo feedback-controlled hydrostatic journal bearing and dynamics of model is analyzed with different control techniques. The fractional-order PID control system is tuned by using particle swarm optimization and Nelder mead optimization techniques with the help of using multi-objective performance criteria.

The results of the current research are compared with previously published theoretical and experimental results. The proposed servo-controlled active bearing system is studied under a number of different dynamic situations and constraints of variable spindle speed, external load, temperature changes (viscosity) and variable bearing clearance (oil film thickness). The simulation results show that the proposed system has better performance in terms of controllability, faster response, stability, high stiffness and strong resistance.

This paper develops an accurate mathematical model for servo-controlled hydrostatic bearing with fractional order controller. The results are in excellent agreement with previously published literature.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0272