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Shaft orbit is an important characteristic for vibration monitoring and diagnosing system of hydroelectric generating set. Because of the low accuracy and poor reliability of traditional methods in identifying the shaft orbit moving direction (MD), the purpose of this paper is to present a novel automatic identification method based on trigonometric function and polygon vector (TFPV).

First, some points on shaft orbit were selected with inter‐period acquisition method and joined together orderly to form a complex plane polygon. Second, by using the coordinate transformation and rotation theory, TFPV were applied comprehensively to judge the concavity or convexity of the polygon vertices. Finally, the shaft orbit MD is identified.

The simulation and experiment demonstrate that the method proposed can effectively identify the common shaft orbit MD.

In order to identity the shaft orbit MD effectively, a novel automatic identification method based on TFPV is proposed in this paper. The problem of identifying the shaft orbit MD is transformed into the problem about orientation of complex polygons, which are formed orderly by points on orbit shaft, and TFPV are applied comprehensively to judge the concavity or convexity of the polygon vertices.

Continuum manipulators are often used in complex and narrow space in recent years because of their flexibility and safety. Vision is considered to be one of the most direct methods to obtain its spatial shape. However, with the improvement of the cooperation requirements of multiple continuum manipulators and the increase of space limitation, it is impossible to obtain the complete spatial shape information of multiple continuum manipulators only by several cameras.

This paper proposes a fusion method using inertial navigation sensors and cameras to reconstruct the shape of continuum manipulators in the whole workspace. The camera is used to obtain the position information, and the inertial navigation sensor is used to obtain the attitude information. Based on the above two information, the shape of the continuum manipulator is reconstructed by fitting Bézier curve.

The experiment result of single continuum manipulator shows that the cubic Bézier curves is applicable to curve fitting of variable curvature, the maximum fitting error is about 2 mm. Meanwhile, the experiment result shows that this method is not affected by obstacles and can still reconstruct the shape of the continuum manipulators in 3-D space by detecting the position and attitude information of the end.

According to the authors’ knowledge, this is the first study on spatial shape reconstruction of multiple continuum manipulators and the first study to introduce inertial navigation sensors and cameras into the field of shape reconstruction of multiple continuum manipulators in narrow space. This method is suitable for shape reconstruction of manipulator with variable curvature continuum manipulator. When the vision of multiple continuum manipulators is blocked by obstacles, the spatial shape can still be reconstructed only by exposing the end point. The structure is simple, but it has certain accuracy within a certain range.

Binder jetting (BJ) process is an additive manufacturing (AM) process in which powder materials are selectively joined by binder materials. Products can be manufactured layer-by-layer directly from three-dimensional model data. The quality properties of the products fabricated by the BJ AM process are significantly affected by the process parameters. To improve the product quality, the optimal process parameters need to be identified and controlled. This research works with the 420 stainless steel powder material.

This study focuses on four key printing parameters and two end-product quality properties. Sixteen groups of orthogonal experiment designed by the Taguchi method are conducted, and then the results are converted to signal-to-noise ratios and analyzed by analysis of variance.

Five sets of optimal parameters are concluded and verified by four group confirmation tests. Finally, by taking the optimal parameters, the end-product quality properties are significantly improved.

These optimal parameters can be used as a guideline for selecting proper printing parameters in BJ to achieve the desired properties and help to improve the entire BJ process ability.

This paper aims to provide a comprehensive review of the state-of–the-art design methods for additive manufacturing (AM) technologies to improve functional performance.

In this survey, design methods for AM to improve functional performance are divided into two main groups. They are design methods for a specific objective and general design methods. Design methods in the first group primarily focus on the improvement of functional performance, while the second group also takes other important factors such as manufacturability and cost into consideration with a more general framework. Design methods in each groups are carefully reviewed with discussion and comparison.

The advantages and disadvantages of different design methods for AM are discussed in this paper. Some general issues of existing methods are summarized below: most existing design methods only focus on a single design scale with a single function; few product-level design methods are available for both products’ functionality and assembly; and some existing design methods are hard to implement for the lack of suitable computer-aided design software.

This study is a useful source for designers to select an appropriate design method to take full advantage of AM.

In this survey, a novel classification method is used to categorize existing design methods for AM. Based on this classification method, a comprehensive review is provided in this paper as an informative source for designers and researchers working in this field.

This paper aims to design an event-triggered adaptive prescribed performance controller for flexible manipulators, with the primary objectives of achieving output performance constraints and addressing communication resource limitations.

The authors propose a novel prescribed performance barrier Lyapunov function (PP-BLF) that considers both output and tracking performance constraints. The PP-BLF ensures that the system's output, transient behavior and steady-state performance, adhere to prescribed constraints. The boundary of the PP-BLF is established by an exponential function that decays over time. Notably, the PP-BLF can be applied seamlessly in unconstrained cases without necessitating controller redesign. Moreover, the controller design incorporates an event-triggered mechanism, effectively reducing the frequency of controller updates and optimizing the utilization of communication resources. Additionally, the authors employ adaptive techniques to estimate the system's unknown parameters and approximate unknown nonlinear functions using radial basis function neural networks (RBFNN). To address the challenge of “complexity explosion”, dynamic surface technology is employed.

Numerical simulations are conducted under five different cases to verify the effectiveness of the proposed controller. The results demonstrate that the controller successfully constrains the output tracking error within the prescribed performance boundary. Moreover, compared with the traditional time-triggered mechanism, the event-triggered mechanism significantly reduces the controller's update frequency, resolving the problem of limited communication resources.

The paper reduces the update frequency of control signals and improves resource utilization through an event-triggered mechanism in the form of relative thresholds. The authors recognize that the event-triggered mechanism may impact the output performance of the system. To address this challenge, the authors propose a prescribed performance Barrier Lyapunov Function (PP-BLF). The PP-BLF is designed to effectively constrain the output performance of the system, ensuring satisfactory control even when the control signal updates are reduced.

In this paper, the authors aim to study the optimal strategy of original equipment manufacturers (OEMs) considering both consumer segmentation and upward substitution of remanufactured products in the product life cycle.

In this paper, the authors develop two remanufacturing models: the OEM remanufacturing model and the authorized remanufacturing model. Then, the authors study the impact of both green consumers' scale and the product life cycle expressed as the market growth rate on the OEM's optimal decision-making. Therefore, the authors derive the optimal solutions of the two models by using game theory.

The authors find that in the case of low market growth rate, when there only exist ordinary consumers, if the substitutability of remanufactured products produced by the OEM is below one threshold or above another threshold, the OEM can obtain higher profit in the OEM remanufacturing model, and vice versa. If the substitutability of remanufactured products produced by the OEM is below a threshold when there are both ordinary and green consumers, the OEM prefers the authorized remanufacturing model; and vice versa. Moreover, in the case of high market growth rate, the OEM prefers the OEM remanufacturing model only when the substitution-level in OEM remanufacturing model is above a threshold.

The present study fills the gap in existing researches by simultaneously discussing product life cycle and green consumers' scale. The authors provide manufacturers with a new basis for remanufacturing decisions.

Servitization of products is becoming increasingly prevalent among manufacturing enterprises. Existing research has primarily focused on exploring whether the direct impact of servitization on manufacturer performance follows a linear or a curvilinear relationship. However, the understanding of the underlying mechanisms between servitization and manufacturer financial performance remains limited. This paper aims to examine the non-linear relationship between servitization and manufacturer performance as well as the mediating process and boundary condition associated with this relationship.

Drawing on resource-advantage theory, this paper proposes a theoretical model of the U-shaped relationship between servitization and the financial performance of equipment manufacturers. Panel data of 248 listed equipment manufacturers in China during the period of 2010–2020 are used to test each hypothesis through the ordinary least square method.

The empirical results indicate that servitization follows a U-shaped relationship with service business focus and the financial performance of equipment manufacturers. Service business focus mediates this U-shaped relationship between servitization and financial performance, and digital technology application moderates this relationship.

This paper pioneers the unraveling of the potential mechanism that can explain the curvilinear relationship between servitization of manufacturers and financial performance. This mechanism is the focus of the service business, which is theoretically delineated and empirically tested. Furthermore, digital technology application enables manufacturers to achieve service business focus more effectively in the process of servitization. Thus, this study addresses the call for research on digital servitization.

45 steel is a common material for the manufacture of various components such as shafts or gears. However, its poor surface properties often limit its applications. The purpose of this paper is to find a way to enhance the surface performance of 45 steel, which is expected to improve the wear resistance of 45 steel.

Double glow plasma surface metallurgy technique was used to prepare hafnium carbide (HfC) coatings on the surface of the 45 steel with two preparation process; one is to diffuse two elements together, while the other is to diffuse step by step. The scanning electronic microscopy and the X-ray diffraction were used to analyze the morphology and phase of the HfC coatings. And then the wear tests were carried out for this coating.

Coating diffused step by step shows better performance; it has a 15-µm alloyed layer which is uniform and dense and its hardness can reach up to 1326.5 Vickers-hardness (HV). While the coating fabricated by diffusing elements together owns a 10-µm alloyed layer and its hardness is 1204.1 HV. According to the wear test results, both coatings have a protective effect on the substrate and the coating prepared by step-by-step diffusion process has less wear volume, indicating that it possesses better friction reduction.

A new method which diffuses elements together was successfully used to prepare compound HfC coating, which can reduce the cost of coating preparation and improve the efficiency of coating preparation.

The purpose of this study is to propose a systematic model selection procedure for long-term load forecasting (LTLF) for ex-ante and ex-post cases considering uncertainty in exogenous predictors.

The different variants of regression models, namely, Polynomial Regression (PR), Generalised Additive Model (GAM), Quantile Polynomial Regression (QPR) and Quantile Spline Regression (QSR), incorporating uncertainty in exogenous predictors like population, Real Gross State Product (RGSP) and Real Per Capita Income (RPCI), temperature and indicators of breakpoints and calendar effects, are considered for LTLF. Initially, the Backward Feature Elimination procedure is used to identify the optimal set of predictors for LTLF. Then, the consistency in model accuracies is evaluated using point and probabilistic forecast error metrics for ex-ante and ex-post cases.

From this study, it is found PR model outperformed in ex-ante condition, while QPR model outperformed in ex-post condition. Further, QPR model performed consistently across validation and testing periods. Overall, QPR model excelled in capturing uncertainty in exogenous predictors, thereby reducing over-forecast error and risk of overinvestment.

These findings can help utilities to align model selection strategies with their risk tolerance.

To propose the systematic model selection procedure in this study, the consistent performance of PR, GAM, QPR and QSR models are evaluated using point forecast accuracy metrics Mean Absolute Percentage Error, Root Mean Squared Error and probabilistic forecast accuracy metric Pinball Score for ex-ante and ex-post cases considering uncertainty in the considered exogenous predictors such as RGSP, RPCI, population and temperature.

The authors investigate the extent to which differences in provincial union legislation have impacts on the union earnings premium.

Content analysis of provincial union regulations of 25 provinces is conducted to create two indices: one reflecting the degree of stringency of the local requirement that unions be established in a timely fashion and the other reflecting requirements for employers to negotiate wages with the union. The authors use individual level data from the China Family Panel Studies (CFPS) of 2010 to estimate the union earnings premium.

The authors find that unionised workers in China receive an earnings premium ranging from 6.4 to 9.6%, which is in range of other studies (but not all) for China that tend to find a (perhaps surprising) union wage premium in spite of the fact that unions tend to be “company unions” designed to foster stability and growth and to serve as a transmission belt for the wishes of the Party rather than bargaining for the benefit of their members. The authors also find that provincial requirements to establish unions in a timely fashion enhance the impact of unions on the earnings of their members, but provincial requirements to negotiate wages dampen the effect of unions on the earnings of their members. Reasons for these results are discussed.

Despite this lack of independence of the Chinese unions, research continuously finds that Chinese unions have effects that are surprisingly similar to those of unions in Western countries. This paper drills deeper into the underlying mechanisms to see if local union strategies, exemplified by provincial union legislation, can explain the unexpected union effects on compensation. To the authors’ knowledge, this is the first paper to do so. Moreover, the authors use individual-level data in contrast to most studies on China that use firm or provincial level aggregate data.