Wangping Wu, Xiang Wang, Qun Wang, Jianwen Liu, Yi Zhang, Tongshu Hua and Peng Jiang
The purpose of this paper is to maraging 18Ni-300 steel fabricate by powder bed based selective laser melting (SLM) process. Microstructure and mechanical properties of the…
Abstract
Purpose
The purpose of this paper is to maraging 18Ni-300 steel fabricate by powder bed based selective laser melting (SLM) process. Microstructure and mechanical properties of the maraging steel part before and after heat treatment at a slow cooling rate were investigated.
Design/methodology/approach
The microstructure of the printed part was observed by optical microscopy and scanning electron microscopy. The phases were determined by X-ray diffraction. The surface roughness of the part was recorded by a profilometer. The tensile properties and microhardness of the parts before and after heat treatment were characterized by an electronic universal tensile testing machine and a Vickers hardness tester, respectively.
Findings
Maraging 18Ni-300 steel part comprised of the martensitic phase and a small fraction of austenite phase. After heat treatment, the volume fraction of austenite slightly increased. The surface roughness of the part was about 96 µm. The printed part was dense, but irregular pores were present. The yield strength, ultimate tensile strength (UTS), elongation and Young’s modulus of as-fabricated parts were 554.7 MPa, 1173.1 MPa, 10.9% and 128.9 GPa, respectively. The yield strength, UTS, elongation and Young’s modulus of as-treated parts were 2065 MPa, 2225 MPa, 4.2% and 142.5 GPa, respectively. The microhardness values of surface and cross-section of the as-fabricated part were 407.1 HV and 443.0 HV, respectively. After short-time heat treatment, the microhardness values of the surface and cross-section of the part were 542.7 HV and 567.3 HV, respectively. After long-time heat treatment, the microhardness values of the surface and cross-section of the part were 524.4 HV and 454.8 HV, respectively. The microhardness and tensile strength increased significantly with decreasing elongation due to the changes in phases and microstructure of the parts after heat treatment.
Originality/value
This work studied the effect of heat treatment at 550°C combined with a subsequent slow cooling rate on microstructure and mechanical properties of maraging 18Ni-300 steel obtained by the powder bed based SLM process.
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Mingming Guo, Hua Zhang, Chuncheng Feng, Manlu Liu and Jianwen Huo
This paper aims to present a method to improve the sensitive and low probabilities of false alarm of a manipulator in a human–robot interaction environment, which can improve the…
Abstract
Purpose
This paper aims to present a method to improve the sensitive and low probabilities of false alarm of a manipulator in a human–robot interaction environment, which can improve the performance of the system owing to non-linear uncertainty in the model of the robot controller.
Design/methodology/approach
A novel collision detection method based on adaptive residual estimation is proposed, promoting the detection accuracy of the collision of the manipulator during operation. First, a general momentum residual estimator is designed to incorporate the non-linear factors of the manipulator (e.g. joint friction, speed and acceleration) into the residual-related uncertainty of the model. Second, model parameters are estimated through gradient correction. The residual filter is used to determine the dynamic threshold, resulting in higher detection accuracy. Finally, the performance of the residual estimation scheme is evaluated by comparing the dynamic threshold with residual in real-time experiments where a single Universal Robot 5 robot end–effector collides with the obstacle.
Findings
Experimental results demonstrate that the collision detection system can improve sensitivity and lead to low probabilities of false alarm of non-linear uncertainty in the model.
Practical implications
The method proposed in this article can be applied to industry and human–robot interaction area.
Originality/value
An adaptive collision detection method is proposed in this paper to address non-linear uncertainties of the model in industrial application.
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Manlu Liu, Rui Lin, Maotao Yang, Anaid V. Nazarova and Jianwen Huo
The characteristics of spherical robots, such as under-drive, non-holonomic constraints and strong coupling, make it difficult to establish its motion control model accurately. To…
Abstract
Purpose
The characteristics of spherical robots, such as under-drive, non-holonomic constraints and strong coupling, make it difficult to establish its motion control model accurately. To improve the anti-interference performance of spherical robots in practical engineering, this paper proposes a spherical robot motion controller based on auto-disturbance rejection control (ADRC) with parameter tuning.
Design/methodology/approach
This paper considers the influences of the spherical shell, internal frame and pendulum on the movement of the spherical robot during the rotation to establish the multi-body dynamics model of the XK-I spherical robot. Due to the serious coupling problem of the dynamic model, the motion control state equation is constructed using linearization and decoupling. The XK-I spherical robot PSO-ADRC motion controller with parameter tuning function is designed by combining the state equation with the particle swarm optimization (PSO) algorithm. Finally, experiments are performed to evaluate the feasibility of PSO-ADRC in an actual case compared to ADRC, PSO-PID and PID.
Findings
By analyzing the required time to reach the expected value, the control stability and the fluctuation range of the standard deviation after reaching the expected value, the superiority of PSO-ADRC to ADRC, PSO-PID and PID is demonstrated in terms of the speed and anti-interference ability.
Practical implications
The proposed method can be applied to the robot control field.
Originality/value
A parameter-tuning method for auto-disturbance-rejection motion control of the spherical robot is proposed. According to the experimental results, the anti-interference ability of the spherical robot moving on uneven ground is improved. Therefore, it provides a foundation for the autonomous environmental monitoring of the spherical robot equipped with sensors.
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Suja Chaulagain, Jianwen Li and Abraham Pizam
Resident satisfaction is a catalyst for continuing care retirement communities (CCRCs) to enhance their competitiveness in the expanding senior living market. CCRC attributes play…
Abstract
Purpose
Resident satisfaction is a catalyst for continuing care retirement communities (CCRCs) to enhance their competitiveness in the expanding senior living market. CCRC attributes play an imperative role in resident satisfaction when older adults reside in these communities. The purpose of this study was to identify the attributes that affect CCRC resident satisfaction and quantify their relative levels of importance. In addition, the impact of resident satisfaction on word of mouth (WOM) and satisfaction with life was examined.
Design/methodology/approach
The proposed hypotheses were tested by performing structural equation modeling on the data collected from 332 CCRC residents throughout the USA.
Findings
The study results revealed that all 10 of the CCRC attributes identified in this study significantly influenced resident satisfaction. Sociopsychological factors had the strongest influence on resident satisfaction, followed by cost and value, medical services, availability of activities, food and beverage services, design, rooms, management and staff, location, and spiritual environment. The study results further indicated that resident satisfaction had a positive impact on WOM and satisfaction with life.
Practical implications
This study provides significant practical implications for CCRC owners and operators to help them better identify the types of CCRC attributes and their relative levels of importance for resident satisfaction.
Originality/value
This study is one of the first comprehensive studies to identify CCRC attributes associated with resident satisfaction and examine the impact of resident satisfaction on satisfaction with life within the senior living field.
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Wujiu Pan, Heng Ma, Jian Li, Qilong Wu, Junyi Wang, Jianwen Bao, Lele Sun and Peng Gao
Aero-engine casings commonly use composite cylindrical shell structures with excellent properties such as corrosion resistance and fatigue resistance. Still, their vibration…
Abstract
Purpose
Aero-engine casings commonly use composite cylindrical shell structures with excellent properties such as corrosion resistance and fatigue resistance. Still, their vibration behavior is relatively complex and may cause fatigue vibration damage, so it is essential to analyze the vibration characteristics of composite cylindrical shells. The purpose of this paper is to analyze the vibration characteristics of multilayer composite cylindrical shells subjected to external pressures and having different interlayer thickness ratios and provide some theoretical basis for the fatigue damage prediction of cylindrical shell casing to ensure the safety and stability of the engine during flight.
Design/methodology/approach
Firstly, the vibration differential equation with external pressure is established based on Soedel theory considering nonlinear effects, while four symmetric boundary conditions are chosen to constrain the cylindrical shell. Then the Rayleigh–Ritz method, which is more efficient and accurate in calculating large structural systems, is applied to solve the problem, and the theoretical model of three-layer cylindrical shell under external pressure is established. The accuracy of the model is verified by comparing the data with the specialized literature. Subsequently, the effects of different external pressures and different thickness-to-diameter ratios, different length-to-diameter ratios and different interlayer thickness percentages on the natural frequency of multilayer composite cylindrical shells were investigated by control variable analysis.
Findings
The conclusions obtained show that the external pressure increases the natural frequency of the cylindrical shell and that the frequency characteristics of the cylindrical shell vary for different boundary conditions. The effect of length-to-diameter ratio, thickness-to-diameter ratio and the percentage of the thickness of the intermediate layer on the natural frequency of the cylindrical shell are significantly increased under external pressure. Because the presence of external pressure increases the frequency of the cylindrical shell by about 70%, it has almost no effect on the frequency at the minimum number of circumferential waves, and the effect on the frequency at the maximum number of circumferential waves is reduced to about 50%. The frequencies in the SL-SL boundary condition are all in perfect agreement with the S-S boundary condition under the influence of different influencing factors.
Originality/value
In this paper, the effect of external pressure and the natural properties of the cylindrical shell under external pressure on the cylindrical shell’s frequency is considered, emphasizing the effect of different layer thickness ratios on the frequency. This paper aims to summarize the changing law between the natural frequency of the cylindrical shell itself and different design parameters during the flight pressure process. Reliable theoretical predictions are provided for analyzing the vibrational behavior of shells subjected to external pressures in aerospace, as well as a database for the practical production of cylindrical shells.
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Rui Lin, Qiguan Wang, Xin Yang and Jianwen Huo
In complex environments, a spherical robot has great application value. When the pendulum spherical robot is stopped or disturbed, there will be a periodic oscillation. This…
Abstract
Purpose
In complex environments, a spherical robot has great application value. When the pendulum spherical robot is stopped or disturbed, there will be a periodic oscillation. This situation will seriously affect the stability of the spherical robot. Therefore, this paper aims to propose a control method based on backstepping and disturbance observers for oscillation suppression.
Design/methodology/approach
This paper analyzes the mechanism of oscillation. The oscillation model of the spherical robot is constructed and the relationship between the oscillation and the internal structure of the sphere is analyzed. Based on the oscillation model, the authors design the oscillation suppression control of the spherical robot using the backstepping method. At the same time, a disturbance observer is added to suppress the disturbance.
Findings
It is found that the control system based on backstepping and disturbance observer is simple and efficient for nonlinear models. Compared with the PID controller commonly used in engineering, this control method has a better control effect.
Practical implications
The proposed method can provide a reliable and effective stability scheme for spherical robots. The problem of instability in real motion is solved.
Originality/value
In this paper, the oscillation model of a spherical robot is innovatively constructed. Second, a new backstepping control method combined with a disturbance observer for the spherical robot is proposed to suppress the oscillation.
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YunYing (Susan) Zhong, Timothy Bottorff, Jianwen Li, Ladda Thiamwong and Susanny J. Beltran
This study aims to examine the conceptual and empirical operations of hospitality at its intersections with health care, which includes medical and senior care.
Abstract
Purpose
This study aims to examine the conceptual and empirical operations of hospitality at its intersections with health care, which includes medical and senior care.
Design/methodology/approach
This study conducts a systematic review of literature on hospitality in health care published in hospitality, tourism and leisure journals spanning from 1990 to 2023. A total of 50 studies meeting the inclusion criteria are reviewed, providing insights into how hospitality is conceptualized, its practical implementation and the proposed outcomes in health-care settings.
Findings
Hospitality in health care is conceptualized by hospitality scholars in three main ways: as service functions, as a service exchange and as an organizational culture. There is a significant overlap between the notion of hospitality and the concept of person-centered care in gerontology and health-care literature. Also, hospitality contributes positively to patient/resident experiences, organizational performance and societal impacts.
Research limitations/implications
The study is limited by its focus solely on the theoretical and practical aspects of hospitality in health care within hospitality, tourism and leisure journals, excluding relevant literature from gerontological and health-care journals.
Originality/value
Interdisciplinary research requires scholars from different disciplines to develop a common language and understanding of key concepts. This study presents the conceptual and practical domains of hospitality and its relevancy to health-care research and offers future directions to strengthen the interdisciplinary research between hospitality, health care and gerontology.
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Xiaolong Zhou, Pinghao Wang, Sixian Chan, Kai Fang and Jianwen Fang
Visual object tracking plays a significant role in intelligent robot systems. This study aims to focus on unlocking the tracking performance potential of the deep network and…
Abstract
Purpose
Visual object tracking plays a significant role in intelligent robot systems. This study aims to focus on unlocking the tracking performance potential of the deep network and presenting a dynamic template update strategy for the Siamese trackers.
Design/methodology/approach
This paper presents a novel and efficient Siamese architecture for visual object tracking which introduces densely connected convolutional layers and a dynamic template update strategy into Siamese tracker.
Findings
The most advanced performance can be achieved by introducing densely connected convolutional neural networks that have not yet been applied to the tracking task into SiamRPN. By using the proposed architecture, the experimental results demonstrate that the performance of the proposed tracker is 5.8% (area under curve), 5.4% expected average overlap (EAO) and 3.5% (EAO) higher than the baseline on the OTB100, VOT2016 and VOT2018 data sets and achieves an excellent EAO score of 0.292 on the VOT2019 data set.
Originality/value
This study explores a deeper backbone network with each convolutional network layer densely connected. In response to tracking errors caused by templates that are not updated, this study proposes a dynamic template update strategy.
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Wuzhu Yan, Zhufeng Yue and Jianwen Feng
The present work aims to reveal the effect of deposition paths on transient temperature, transient stress, residual stress and residual warping in the electron beam freeform…
Abstract
Purpose
The present work aims to reveal the effect of deposition paths on transient temperature, transient stress, residual stress and residual warping in the electron beam freeform fabrication (EBF) process.
Design/methodology/approach
Six typical deposition paths were involved in the finite element (FE) simulations of EBF process by implementing a specially written program.
Findings
The results showed that the deposition path had a remarkable influence on heat transfer and transient temperature distribution in the scanning process, resulting in different residual stress and residual warping after cooling to room temperature. The largest and smallest temperature gradients were obtained from the zigzag and alternate-line paths, respectively. Meanwhile, the temperature gradient decreased with the increase of deposited layers. The optimum deposition path, namely, the alternate-line pattern, was determined with respect to the residual stress and residual warping.
Originality/value
Although some researcher revealed the importance of deposition path through FE analysis and experimental observation, their studies were usually confined within one type of deposition pattern. A complete investigation of typical deposition paths and comparison among them are still lacking in literature. To address the aforementioned gap, the present work started by extensive FE simulations of EBF process involving six representative deposition paths, namely, the alternate-line, zigzag, raster, inside-out spiral, outside-in spiral and Hilbert. For each deposition path, the transient temperature field, residual stress and residual deformation were obtained to optimize the deposition path.
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Fabio Santagata, Jianwen Sun, Elina Iervolino, Hongyu Yu, Fei Wang, Guoqi Zhang, P.M. Sarro and Guoyi Zhang
The purpose of this paper is to demonstrate a novel 3D system-in-package (SiP) approach. This new packaging approach is based on stacked silicon submount technology. As…
Abstract
Purpose
The purpose of this paper is to demonstrate a novel 3D system-in-package (SiP) approach. This new packaging approach is based on stacked silicon submount technology. As demonstrators, a smart lighting module and a sensor systems were successfully developed by using the fabrication and assembly process described in this paper.
Design/methodology/approach
The stacked module consists of multiple layers of silicon submounts which can be designed and fabricated in parallel. The 3D stacking design offers higher silicon efficiency and miniaturized package form factor. This platform consists of silicon submount design and fabrication, module packaging, system assembling and testing and analyzing.
Findings
In this paper, a smart light emitting diode system and sensor system will be described based on stacked silicon submount and 3D SiP technology. The integrated smart lighting module meets the optical requirements of general lighting applications. The developed SiP design is also implemented into the miniaturization of particular matter sensors and gas sensor detection system.
Originality/value
SiP has great potential of integrating multiple components into a single compact package, which has potential implementation in intelligent applications.