Search results

In order to replace the conventional human maintenance of cable‐stayed bridges, a robot is designed and constructed for tasks such as cleaning, painting and rust‐detecting.

Adopting a modular approach, two kinds of climbing mechanisms, plus a painting mechanism and a rust‐detecting method are designed.

A robot that can climb and maintain the cables of cable‐stayed bridges has been designed and constructed. It has been proved by experiment that the robot can overcome many disadvantages of conventional human bridge‐maintenance, and drastically improve efficiency, cost, and safety.

The robot is of industrial size, but a new mechanism requiring less installing time will be designed for the future.

The robot has been applied to cables of the Nanpu Bridge and Xupu Bridge in Shanghai. More than 80 cable‐stayed bridges and six suspension bridges have been built or are being constructed across large rivers in China alone. This gives an enormous potential market.

The cable maintenance robot developed in this paper is the world's first special robot for the cables of cable‐stayed bridges.

This paper aims to propose a new method for combining global path planning with local path planning, to provide an efficient solution for unmanned surface vehicle (USV) path planning despite the changeable environment. Path planning is the key issue of USV navigation. A lot of research works were done on the global and local path planning. However, little attention was given to combining global path planning with local path planning.

A search of shortcut Dijkstra algorithm was used to control the USV in the global path planning. When the USV encounters unknown obstacles, it switches to our modified artificial potential field (APF) algorithm for local path planning. The combinatorial method improves the approach of USV path planning in complex environment.

The method in this paper offers a solution to the issue of path planning in changeable or unchangeable environment, and was confirmed by simulations and experiments. The USV follows the global path based on the search of shortcut Dijkstra algorithm. Both USV achieves obstacle avoidances in the local region based on the modified APF algorithm after obstacle detection. Both the simulation and experimental results demonstrate that the combinatorial path planning method is more efficient in the complex environment.

This paper proposes a new path planning method for USV in changeable environment. The proposed method is capable of efficient navigation in changeable and unchangeable environment.

The on‐line concentration and temperature measurement of solutions is of great interest as a means of quality production control in many industrial processes, such as in food service industry, pharmaceuticals industry, chemical industry and environmental engineering, especially for harmful solutions or solutions that cannot be reached by the operator. This paper seeks to address these issues.

A high resolution all‐fiber multi‐parameter sensor system has been studied theoretically and experimentally. The sensor system can be used for on‐line monitoring of concentration and temperature simultaneously and dynamically. A combined long period fiber grating (CLPG) is used as the sensor head based on its resonance wavelength shifts being almost linearly with concentration and temperature, and also based on that the two applied resonance peaks have different concentration‐wavelength coefficients and different temperature‐wavelength coefficients. Two wavelength‐matched fiber Bragg gratings (FBGs) are used to convert resonance peak wavelengths of the CLPG into corresponding intensities for interrogation.

When the concentration and the temperature all fluctuate dynamically during experiments, a concentration resolution of 0.03 g/L has been achieved in the range of 0∼200 g/L, and a temperature resolution of 0.02C has been realized in the range of −20∼60C.

On‐line monitoring of concentration and temperature for solutions is a means of quality production control in biological, chemical and other many industrial processes, such as in food service industry, pharmaceuticals industry, chemical industry, and also in environmental engineering, especially for harmful solutions or solutions that cannot be reached by the operator. Optical fiber sensors have numerous advantages over traditional sensors, such as immunity to electromagnetic interference, higher stability and sensitivity, more easiness of multiplex, being competent for application in harsh environments, “smart structures” and on‐site measurements. Long period optical fiber grating sensor is the most appropriate sensor for multi‐parameter monitoring in the fields mentioned above, which has all the advantages of optical fiber sensor. Besides, optical fiber grating sensors can be used for monitoring more accurately because its signal is coded by wavelength. The all‐fiber sensor system is suitable for remote monitoring of many solutions, such as the solutions of NaCl, glucose, alcohol, and hydrocarbon.

This study examines chronic illness, disability and social inequality within an exposure-vulnerabilities theoretical framework.

Using the National Survey of Drug Use and Health (NSDUH), a preeminent source of national behavioral health estimates of chronic medical illness, stress and disability, for selected sample years 2005–2014, we construct and analyze two foundational hypotheses underlying the exposure-vulnerabilities model: (1) greater exposure to stressors (i.e., chronic medical illness) among racial/ethnic minority populations yields higher levels of serious psychological distress, which in turn increases the likelihood of medical disability; (2) greater vulnerability among minority populations to stressors such as chronic medical illness exacerbates the impact of these conditions on mental health as well as the impact of mental health on medical disability.

Results of our analyses provided mixed support for the vulnerability (moderator) hypothesis, but not for the exposure (mediation) hypothesis. In the exposure models, while Blacks were more likely than Whites to have a long-term disability, the pathway to disability through chronic illness and serious psychological distress did not emerge. Rather, Whites were more likely than Blacks and Latinx to have a chronic illness and to have experienced severe psychological distress (both of which themselves were related to disability). In the vulnerability models, both Blacks and Latinx with chronic medical illness were more likely than Whites to experience serious psychological distress, although Whites with serious psychological distress were more likely than these groups to have a long-term disability.

Several possibilities for understanding the failure to uncover an exposure dynamic in the model turn on the potential intersectional effects of age and gender, as well as several other covariates that seem to confound the linkages in the model (e.g., issues of stigma, social support, education).

This study (1) extends the racial/ethnic disparities in exposure-vulnerability framework by including factors measuring chronic medical illness and disability which: (2) explicitly test exposure and vulnerability hypotheses in minority populations; (3) develop and test the causal linkages in the hypothesized processes, based on innovations in general structural equation models, and lastly; (4) use national population estimates of these conditions which are rarely, if ever, investigated in this kind of causal framework.

This study examines the effect of contextual perceived value activated by contextual marketing offers and information privacy concerns on consumer loyalty in mobile commerce.

The survey was conducted through 340 mobile users in Morocco and the collected data were analyzed using structural equation modeling.

This study's results show that contextual marketing and information privacy concerns are key determinants in improving customer loyalty in the m-commerce context. Perceived ubiquity has a positive impact on perceived trust, which also impacts consumer loyalty. Information privacy concerns also have a positive impact on customer satisfaction, yet it does not impact perceived trust, which is contrary to the results of other researchers. It can also be concluded that customer satisfaction and trust are important antecedents of consumer loyalty.

This research gives rise to some important managerial and strategic implications in order to integrate contextual marketing strategies, as well as theoretical implications that concern this field of study.

This research makes a significant contribution to knowledge by examining the role of contextual marketing and information privacy concerns in the m-commerce context. These results will be considered useful for marketers and for businesses in general who wish to integrate a marketing strategy that is based on a customer-centric approach. It also contributes to the related literature, as there are few studies focused on m-commerce and contextual marketing within the context of Morocco.

This paper aims to study the electrochemical corrosion performance of ultrafine-grained (UFG) Cu bulk in 0.5 M NaCl solution.

UFG Cu bulk were prepared by impacting at −196°C and following heat treatment. The electrochemical corrosion behaviors of coarse-grained (CG), impacted and subsequently annealed at 190°C Cu bulks were studied.

All the bulks displayed typical active-passive-transpassive behaviors (dual passive films without stable passive regions). The resistance to corrosion of impacted Cu bulk was notably superior to that of CG Cu bulk, and subsequently annealing further improved its corrosion resistance.

Except for mechanical properties, corrosion performance has been considered to be one of the most important aspects in bulk UFG metallic materials research for the prospective engineering applications.

Cryogenic impacting could effectively reduce grain size of CG Cu bulk to UFG scale and induce high density dislocation. Subsequent annealing resulted in a further decrease of grain size even to nanoscale, as well as nanometer twins. The grain refinement, high density dislocation and annealing twins effectively enhance the passivation capability, resulting in an increase in the corrosion resistance.

This paper aims to present an adaptive fuzzy sliding mode controller with nonlinear observer (AFSMCO) for the redundant robotic manipulator handling a varying payload to achieve a precise trajectory tracking in the task space. This approach could be applied to solve the problems caused by the dynamic effect of the varying payload to robotic system caused by model uncertainties.

First, a suitable observer using the recursive algorithm is presented for an accurate estimation of external disturbances caused by a variable payload. Second, the adaptive fuzzy logic is designed to approximate the parameters of the sliding mode controller combined with nonlinear observer (SMCO) to avoid chattering in real time. Moreover, Lyapunov theory is applied to guarantee the stability of the proposed closed-loop robotic system. Finally, the effectiveness of the proposed control approach and theoretical discussion are proved by simulation results on a seven-link robot and demonstrated by a humanoid robot platform.

The varying payload leads to large variations in the dynamics of the manipulator and the tracking error. To achieve high-precision position tracking, nonlinear observer was introduced to feed into the sliding mode control (SMC) which had improved the ability to resist the external disturbance. In addition, the chattering caused by the SMC was eliminated by recursively approximating the switching gain with the usage of adaptive fuzzy logic. Therefore, a distributed control strategy solves the problems of an SMC implementation in improving its tracking performance and eliminating the chattering of the system control.

The AFSMCO is proposed for the first time and used to control the redundant robotic manipulator that handles the varying payload. The proposed control algorithm possesses better robustness and higher precision for the trajectory tracking than classical SMC.

The purpose of this paper is to supplement and upgrade existing research on LPBF of NiTi alloys. Laser powder bed fusion (LPBF) is a promising method for fabricating nickel–titanium (Ni–Ti) alloys. It is well known that the energy density is mainly adjusted through the scanning speed and laser power. Nevertheless, there is lack in research on the effects of separately adjusting the scanning speed and laser power on the properties of the final Ni–Ti components. On the other hand, although Ni-rich Ni–Ti alloys [such as Ni54(at.%)Ti] have great potential in structural applications because of their high hardness and good shape stability, at present, there are few studies focusing on this grade of Ni–Ti alloy.

In this work, the energy density was adjusted by changing the laser power and scanning speed separately, and the corresponding process parameters were used to fabricate Ni54(at.%)Ti alloys. The formability (including the relative density, impurity content, etc.) and tensile properties of the LPBF Ni54(at.%)Ti alloys fabricated with different combinations of process parameters were analyzed.

The effects of increasing the laser power and reducing the scanning speed on the properties of the LPBF Ni54(at.%)Ti alloys and the property differences between components manufactured with different combinations of laser power and scanning speed under the same energy density were analyzed. The optimal process parameters were selected to fabricate the components that achieved the highest ultimate tensile strength of 537 MPa, a high relative density of 98.23%, a relatively low impurity content (0.073 Wt.% of carbon and 0.06 Wt.% of oxygen) and an ideal pseudoelasticity (95% recovery rate loaded at 300 MPa).

The effects of increasing the laser power and reducing the scanning speed on the properties of LPBF Ni54(at.%)Ti alloys were studied in this paper. This work is an upgrade and supplement to the existing research on fabricating Ni-rich Ni–Ti alloys by the LPBF method.

Mechatronics is a very important area of research in industrial applications. The purpose of this study is to find some of the most important components of the literature on this subject.

The analysis is based on the use of the database Compendex; it was searched in the broadest way for documents related to mechatronics. In addition, subject guides from libraries of universities with mechatronics programs were studied to find resources available in those areas.

The literature of mechatronics is extensive and multidisciplinary. Based on the results from Compendex, the following data were found: most productive authors, list of leading journals and conference proceedings, publishers and grant organizations, authors’ affiliations and other minor details. Based on the analysis of subject guides, the following types of resources were found: research databases, reference books and ebook collections.

Part of the analysis is based on a search performed in one technical database, Compendex; it was the database that generated the largest number of citations as compared to Inspec and the Web of Science. The results have a strong English language focus. It is possible that by using the results from multiple data bases, some additional sources could be obtained.

Mechatronics is a relatively new technological field comprising a number of scientific and engineering areas. The results obtained summarized a significant amount of bibliographic information.

The work is original; to the best of the authors’ knowledge, no other study has analyzed the literature on this subject.