Search results

Target tracking systems are generally computationally intensive and require expensive and power‐hungry visual sensors. On the other hand, the existing target tracking control approaches fail to track the target swiftly and accurately when the mobile robot moves in the diversified manoeuvre modes. The purpose of this paper is to propose a novel target tracking control method with a low cost embedded vision system to achieve high accuracy and speediness of target tracking control, regardless of the type of manoeuvre modes.

The pan/tilt angle differences are transformed from the tracking error between the image centre and the coordinates of the target centroid returned by the CMUcam3; the corresponding pan/tilt angle variation rates are calculated based on the manoeuvre control. All of them are fed to the controller. Then the controller generates appropriate control signals to fit the changing speed of target centroid and compensate for the tracking error. The experiments are designed in a way that the CMUcam3 keeps the target centre coincident with the image centre when the mobile robot moves in the diversified manoeuvre modes.

In spite of the type of manoeuvre modes, the controller responds to the tracking error instantly and actuates the pan/tilt with suitable position and speed commands, and the target centroid remains in the bounding box during the entire movement.

The proposed target tracking control takes the correlation between the robot manoeuvre modes and the target tracking control into account, and particularly suits for the target tracking tasks in planetary exploration, surveillance and military applications.

The impact strength of solder joint under high strain rate was evaluated by board level test method. However, the impact shear test of single solder bump was more convenient and economical than the board level test method. With the miniaturization of solder joints, solder joints were more prone to failure under thermal shock and more attention has been paid to the impact reliability of solder joint. But Pb-free solder joints may be paid too much attention and Sn-Pb solder joints may be ignored.

In this study, thermal shock test between −55°C and 125°C was conducted on Sn-37Pb solder bumps in the BGA package to investigate microstructural evolution and growth mechanism of interfacial intermetallic compounds (IMCs) layer. The effects of thermal shock and ball diameter on the mechanical property and fracture behavior of Sn-37Pb solder bumps were discussed.

With the increase of ball size, the same change tendency of shear strength with thermal shock cycles. The shear strength of the solder bumps was the highest after reflow; with the increase of the number of thermal shocks, the shear strength of the solder bumps was decreased. But at the time of 2,000 cycles, the shear strength was increased to the initial strength. Minimum shear strength almost took place at 1,500 cycles in all solder bumps. The differences between maximum shear strength and minimum shear strength were 9.11 MPa and 16.83 MPa, 17.07 MPa and 15.59 MPa in φ0.3 mm and φ0.4 mm, φ0.5 mm and φ0.6 mm, respectively, differences were increased with increasing of ball size. With similar reflow profile, the thickness of IMC decreased as the diameter of the ball increased. The thickness of IMC was 2.42 µm and 2.17 µm, 1.63 µm and 1.77 µm with increasing of the ball size, respectively.

Pb-free solder was gradually used to replace traditional Sn-Pb solder and has been widely used in industry. Nevertheless, some products inevitably used a mixture of Sn-Pb and Pb-free solder to make the transition from Sn-Pb to Pb-free solder. Therefore, it was very important to understand the reliability of Sn-Pb solder joint and more further research works were also needed.

An increasing number of users join and become immersed in WeChat official accounts, but many users quit using these services as well. Nevertheless, most of the previous studies mainly focussed on the usage behavior. The purpose of this paper is to fill the gap by examining factors affecting users’ unfollow intentions for WeChat subscriptions in a Chinese context.

Structural equation modeling is used in our study. A field survey with 260 WeChat users is conducted to test the research model and hypotheses.

The results show the following interesting key findings: first, the effect of actual cost on users’ unfollow intentions is larger than the effect of opportunity cost; second, users’ unfollow intentions will decrease with the increase of users’ perceptions of information usefulness; third, the results of the control variables showed that only landing frequency has a negative effect on users’ unfollow intentions; and fourth, users’ demographic differences are also examined in regard to how they may affect users’ unfollow intentions.

First, this paper studies factors influencing users’ unfollow intentions for WeChat subscriptions from a social exchange theory perspective; the authors considered both extraneous factors and users’ internal perception factors potentially affecting users’ unfollow intentions, which has rarely been researched. Furthermore, the authors examined significant differences among users’ demographic characteristics in affecting users’ unfollow intentions. The results of the study provide a more comprehensive understanding of the influencing factors of users’ unfollow intentions.

The purpose of this paper is to examine the issue of the influential factors of buyer satisfaction and loyalty toward online auction web sites and online auction sellers. Customers' loyalty toward the online auction web site and seller is also explored.

An internet survey is conducted on 221 buyers of online auction.

Loyalty intention toward an online auction seller positively affects a buyer's loyalty intention toward the online auction web site, whereas his/her loyalty intention toward the online auction web site negatively affects his/her loyalty intention toward the online auction seller.

The first is in its cross‐sectional design. Second, this paper examines the antecedents of the online auction web site and the online auction seller in a single country. The findings may have limited generalizability to other countries.

The results of this paper provide less positive news for online auction sellers. Sellers on an online auction web site should be careful in making online auction web site change decisions. Although a seller can secure buyer loyalty intention by providing strong e‐service quality, overall satisfaction and the specific asset investment (SAI), buyers still may not be enthusiastic about moving with the seller to another auction web site.

This paper contributes to comparing the pulling force of the web sites and the sellers, and explains that SAI can affect the buyers through web sites and sellers. There are three parties involved in the model.

This study aims to examine the relationships among open innovation, organizational ambidexterity and firm performance. One important aspect of open innovation is that it enables a firm to develop its organizational ambidexterity capability and become more efficient in using this capability to improve its performance.

The authors introduce a moderated mediation theoretical framework to reveal the bridging role of organizational ambidexterity in the effect of open innovation on firm performance. The theoretical model is empirically validated using survey data from 215 high-tech firms.

The authors find that open innovation plays a moderating role in the relationship between organizational ambidexterity and firm performance. Furthermore, organizational ambidexterity plays a significant mediating role in the relationship between open innovation and firm performance, and open innovation has a nonlinear, inverse U-shaped moderation effect on the relationship between organizational ambidexterity and firm performance.

This is one of the first studies to undertake a moderated mediation analysis by highlighting the mediating role of organizational ambidexterity and the moderating role of open innovation in influencing firm performance. The authors make a theoretical contribution to the field of open innovation and organizational behavior, and the authors provide concrete and feasible decision-making suggestions to decision makers adopting open innovation.

The empirical results can help high-tech firm managers ascertain the organizational ambidexterity practices that can be employed and determine the level of open innovation to enhance firm performance.

This research provides new insights into whether and how firms can grasp the benefits of organizational ambidexterity to undertake open innovation activities. The findings not only contribute to advancing the mediating effect of organizational ambidexterity but also verify the inverse U-shaped moderation of open innovation in the relationship between organizational ambidexterity and firm performance.

The purpose of this paper is to compare the sensing characteristics of uniform fiber Bragg grating (FBG) and tilted fiber Bragg grating (TFBG) by presenting a detailed research review. Temperature, axial strain, bending, vibration and refractive index measurands of FBG and TFBG sensor are presented and some significant differences are found.

Theoretical analysis and practical application in engineering are investigated and compared from other authors' research papers and self analysis. Spectra behavior of both FBG and TFBG are discussed.

There are found to be significant differences in temperature, axial strain, bending, vibration and refractive index sensing characteristics of FBG and TFBG.

The paper's analysis is comprehensive and clear and provides readers with the sensing characteristics of FBG and TFBG in detail.