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This paper aims to investigate the modification of surface of a copper alloy by friction stir surface processing (FSSP).

The metallographic condition of the surface modification was observed using microscopy. Electrochemical corrosion tests were carried out on the modified surface and the corroded surface was observed by scanning electron microscopy (SEM).

The test results showed that FSSP resulted in refinement of the surface grains of the copper alloy. The degree of refinement was increased with rotation speed and increased in the descending distance of the stirring tool. The corrosion resistance of the modified surface was superior to the base metal except for the surface generated by a rotation speed of 800 rpm and a descending distance 0.1 mm. For the surface modification of the rotation speed of 800 rpm, its corrosion resistance was lower than for the other two rotation speeds. When the rotation speed is specified, the corrosion resistance is improved with increased descending distance. When the descending distance is specified, the corrosion resistance is improved with the rotation speed.

In this study, it was confirmed that the corrosion resistance of the surface modification was best at the rotation speed 1200 rpm and descending distance 0.2 mm.

This paper aims to present a broad review of near-a titanium alloys for high-temperature applications.

Following a brief introduction of titanium (Ti) alloys, this paper considers the near-α group of Ti alloys, which are the most popular high-temperature Ti alloys developed for a high-temperature application, particularly in compressor disc and blades in aero-engines. The paper is relied on literature within the past decade to discuss phase stability and microstructural effect of alloying elements, plastic deformation and reinforcements used in the development of these alloys.

The near-a Ti alloys show high potential for high-temperature applications, and many researchers have explored the incorporation of TiC, TiB SiC, Y₂O₃, La₂O₃ and Al₂O₃ reinforcements for improved mechanical properties. Rolling, extrusion, forging and some severe plastic deformation (SPD) techniques, as well as heat treatment methods, have also been explored extensively. There is, however, a paucity of information on SiC, Y₂O₃ and carbon nanotube reinforcements and their combinations for improved mechanical properties. Information on some SPD techniques such as cyclic extrusion compression, multiaxial compression/forging and repeated corrugation and straightening for this class of alloys is also limited.

This paper provides a topical, technical insight into developments in near-a Ti alloys using literature from within the past decade. It also outlines the future developments of this class of Ti alloys.

The purpose of this study is to designed a robot odometry based on three dimensional (3D) laser point cloud data, inertial measurement unit (IMU) data and real-time kinematic (RTK) data in underground spatial features and gravity fluctuations environment. This method improves the mapping accuracy in two types of underground space: multi-layer space and large-scale scenarios.

An IMU–Laser–RTK fusion mapping algorithm based on Iterative Kalman Filter was proposed, and the observation equation and Jacobian matrix were derived. Aiming at the problem of inaccurate gravity estimation, the optimization of gravity is transformed into the optimization of SO(3), which avoids the problem of gravity over-parameterization.

Compared with the optimization method, the computational cost is reduced. Without relying on the wheel speed odometer, the robot synchronization localization and 3D environment modeling for multi-layer space are realized. The performance of the proposed algorithm is tested and compared in two types of underground space, and the robustness and accuracy in multi-layer space and large-scale scenarios are verified. The results show that the root mean square error of the proposed algorithm is 0.061 m, which achieves higher accuracy than other algorithms.

Based on the problem of large loop and low feature scale, this algorithm can better complete the map loop and self-positioning, and its root mean square error is more than double compared with other methods. The method proposed in this paper can better complete the autonomous positioning of the robot in the underground space with hierarchical feature degradation, and at the same time, an accurate 3D map can be constructed for subsequent research.

The purpose of this paper is to improve the behaviors coordination mechanism, to maintain the system's long time‐scale and stable competitive capability, when the agents in the system focus on cooperating with each other.

Effort level for every agent, whose dynamics can be described as a stochastic partial differential equation, and the incentive of effort as the control of the corresponding agent, are introduced to describe agents' behavior abstracted. The cooperative stochastic differential game model is constructed: first, the optimal resolve trajectory mapping with profit maximization of the system are obtained, then the transitory imputation coupled with effort initial state of the system by introducing dynamic Shapley value imputation method. Based on the results obtained, the profit distribution strategies and the equilibration incentive compensation mechanism are given, due to the evolution law of the payoff and the state variable.

It is concluded that: the transitory compensation to agent for efforts and incentive, which can be changed with the system state at current and in history and in future changed, would guarantee the realization of the Shapley value imputation throughout the game horizon.

In this paper, the interactivity between agents in the system is considered first. The dynamical Shapley imputation mechanism and the transitory compensatory mechanism are provided to make the imputation more stable and feasible.

This study highlights the impact of mental accounts on a user's decision-making regarding payment schemes and aims to determine the pricing strategy for the first-enjoy-after-pay service offered by the two-sided media platforms.

This study establishes a game-theoretic model and utilizes backward induction to derive the equilibrium price by maximizing the monopolist's profit.

The findings indicate that the conditions for a two-sided media platform to offer the first-enjoy-after-pay service depend on the trade-off between pleasure attenuation and pain buffering and the effect of time discounts. Moreover, the authors found that the time discount is a critical factor in determining pricing strategies under various payment schemes offered by the platform.

This work adopts a uniform pricing strategy for users who opt for either immediate or post-payment schemes. Nevertheless, it is important to note that this approach has limitations in terms of offering discriminatory pricing for those who choose both payment schemes.

This analytical work provides valuable insights for two-sided media platforms to optimize their payment scheme strategies and pricing considering the influence of a user's mental account.

In a two-sided media platform, the authors provide applicable conditions for the platform to offer first-enjoy-after-pay service considering the effect of mental accounts. Further, the authors show the optimal pricing strategy under different payment schemes provided by the platform.

The purpose of this paper is to use systemic thinking to explain and predict the cost of logistics outsourcing, and to devise policies to minimize the cost of risk.

A method of system dynamics is adopted to capture the dynamic interaction of logistics outsourcing systems and to analyze the impact of some factors in the system on policy decisions over a long‐term horizon.

This paper illustrates the internal mechanism of the logistics outsourcing cost of risk systems by virtue of system dynamic principles, to develop a system dynamics model, and to give a quite detailed description of how the model could work.

The results of the simulation analysis provide useful information for logistics outsourcing risk managers.

This paper contributes to the discussion on the use of system dynamics for studying logistics outsourcing cost of risk.

Public hospitals in China usually rely on revenues from medical services and medications to compensate for major costs given their nonprofit nature. The lack of government subsidies and unreasonable prices of medical services have led to high medical costs and unbalanced reimbursement system for public hospitals. There is a critical need of research on improvement of reimbursement system that will create positive effect on China’s health-care system. This paper aims to focus on four dimensions of stakeholders (government, patients, medical insurance agencies and social organization) and six major expenditures to explore reimbursement scheme for public hospitals in China with the purpose of relieving unbalanced income and expenditure of hospitals, avoiding medication markups and reducing medical expenses from patients.

In this paper, the authors study reimbursement scheme for public hospitals from the perspective of four dimensions of stakeholders and how stakeholders reimburse six major expenditures of hospitals. A total of 128 effective samples were collected from financial data of 32 public hospitals through 2009-2012. This paper analyzes the econometric models of the selected revenue and expenditure. This paper analyzes the econometric models of the selected revenue and expenditure using linear regression. The linear relationship between each cost and different types of incomes (i.e. reimbursements from government, patients, insurance agencies and social organization) is analyzed before and after cancelling the medication markups.

Results from empirical research verify that government reimbursement is insufficient, and using medication markups to compensate for medical service costs has become a serious problem for China’s public hospitals. To avoid the medication markups and improve the reimbursement scheme, government should reimburse labor cost, fixed assets cost and research cost; patients and medical insurance agencies should reimburse the costs of medical service, medication and administration/operations; and social organization should supplement the fixed assets cost.

In this study, the authors defined and classified stakeholders of reimbursement scheme for public hospitals in China, which help understand the roles and effects that different stakeholders can play in compensation. Along with the proposed reimbursement scheme framework, this study will help make effective implementation of new health-care reform program in China.

The purpose of this study is to solve the problem of an unknown initial position in a multi-robot raster map fusion. The method includes two-dimensional (2D) raster maps and three-dimensional (3D) point cloud maps.

A fusion method using multiple algorithms was proposed. For 2D raster maps, this method uses accelerated robust feature detection to extract feature points of multi-raster maps, and then feature points are matched using a two-step algorithm of minimum Euclidean distance and adjacent feature relation. Finally, the random sample consensus algorithm was used for redundant feature fusion. On the basis of 2D raster map fusion, the method of coordinate alignment is used for 3D point cloud map fusion.

To verify the effectiveness of the algorithm, the segmentation mapping method (2D raster map) and the actual robot mapping method (2D raster map and 3D point cloud map) were used for experimental verification. The experiments demonstrated the stability and reliability of the proposed algorithm.

This algorithm uses a new visual method with coordinate alignment to process the raster map, which can effectively solve the problem of the demand for the initial relative position of robots in traditional methods and be more adaptable to the fusion of 3D maps. In addition, the original data of the map can come from different types of robots, which greatly improves the universality of the algorithm.

This study aims to present a novel hydrostatic squeeze film-metal mesh journal bearing (HS-MMJB), which uses both hydrostatic squeeze film damper (HSFD) and metal mesh damper (MMD), to suppress the vibration of rotor-bearing systems.

The lubrication equations were introduced to calculate the dynamic characteristics of HS-MMJB, and the response analyses of rotor systems were carried out. Experiments were conducted to study the vibration reduction of a rotor system with HS-MMJB. In addition, experiments for different oil supply pressures in the HS-MMJB were conducted.

The theoretical and experimental results show that the HS-MMJB exhibits excellent damping and vibration attenuation characteristics. Moreover, the stability of the rotor system can be improved by controlling the oil supply pressure.

There is a dearth of research on vibration characteristics of rotor system support by journal bearing combining HSFD and MMD. Moreover, the active oil pressure control is implemented to improve the stability of rotor system.