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This paper aims to establish a method to optimize reflow profiles and achieve high reliability of solder joints on the basis of the heating factor, Q_η, a measure of the reflow profile related to reliability of reflow processed products.

The focus of the paper is on how to realize the optimal range of Q_η, since there is no need to pay particular attention to the shape of a reflow profile when performing a heating factor‐based optimization. The coldest point on the printed circuit board assembly (PCA), which experiences the minimum heating factor (Q_η^min) during the reflow process, was used to set the lower limit of the optimal range (Q_η^L). If Q_η^min approaches Q_η^L and the temperature difference across the PCA is minimized, then the solder joints on the PCA will all experience heating factors within the optimal range, ensuring high quality reflow soldering. Establishing an initial reflow profile may be performed using profiling software. The resultant oven recipe may then be used as the reference recipe by which to apply the heating factor‐based optimization. A combinatorial parameter, H_t, is defined to represent the temperature settings of all the top heating zones within the heating section of the reflow oven. The relative difference between H_t and each top heating zone temperature setting is derived from the reference recipe, and H_t is then adjusted to achieve Q_η^L for Q_η^min. This is achieved by using a least squares estimation method to build a regression model for Q_η^min versus H_t.

Experiments and regression analysis have demonstrated that Q_η^min varied linearly with H_t, with α denoting its slope. With a measured Q_η^min in response to the reference setup after the first run of a PCA, H_t should be increased by ((Q_η^L−Q_η^min)/α) to attain Q_η^L in the second run. Thereby, a suitable reflow process recipe can be obtained with only two reflow runs where Q_η^min is close to Q_η^L.

The optimal range of heating factor for lead‐free solder pastes is currently unknown, and the method to establish the required oven recipe for achieving a required reflow profile requires further exploration.

Provides a methodology for reducing the risk of process‐related reliability issues in lead‐free soldering.

Q_η^L can be fairly quickly achieved for Q_η^min with the approach established in this paper, facilitating the formation of solder joints with high reliability during the reflow soldering process.

This paper aims to offer a convenient method to develop an oven recipe for a specific soldering profile in a reflow process. The method is devised to quickly achieve proper profile shape and heating factor Q_η, a measure of success for high reliability of the solder joints reflowed.

An in‐depth analysis of the heating mechanism and some experiments of the reflow soldering process are performed to research on how to realize a specific shape reflow profile were conducted.

Heating mechanism analysis and experiments demonstrate that the combinatorial parameters based method is feasible to do thermal profiling.

The mapping function among a particular configured PCBA, an oven used, a target reflow profile and an optimal range of the heating factor should be further established for fast and reliable production of reflow soldering.

Provides a methodology for designing an oven recipe for reflow soldering production.

An oven recipe can be quickly attained with the approach established in this paper, facilitating the formation of solder joints with high reliability during the reflow soldering process.

The purpose of this paper is to design a current transformer model based on the principle of B-dot. It can reflect the change of transmission line current and meet the requirement of automation and intelligence for current measurement in power system.

In this paper, a new type of current transformer is designed on the principle of B-dot, which has the structure of the inverse series of planar air core coils and the form of printed circuit board (PCB). With this structure, the current transformers can induce magnetic field quite well. The finite element simulation for the current transformer with n layers structure is conducted in the Maxwell, which help to optimize the design of the current transformer.

By setting up the experimental platform, the experiment of the current transformer is carried out. The results of the test show that the measurement accuracy can satisfy the requirement of measurement. Besides, the new current transformer has good transient characteristics and can meet the needs of the development of smart grid.

The new type of current transformer is based on the principle of B-dot, which is designed with a new type of non-contact PCB hollow coil current transformer. It has no iron core, no ferromagnetic effect and the phenomenon of ferromagnetic resonance. It has great progress in its insulation performance, volume and bandwidth response. In addition, the planar hollow coil of the inverse series structure can make the structure more accurate.

The cable inspection robot is essential in maintaining bridge cables. The purpose of this paper is to summarize the maintenance methods of bridge cables. It summarizes the advantages and disadvantages of the critical structures of the external overall frame, intermediate adhesion device, attachment mechanism and driving method of the cable inspection robot. Finally, it discusses the challenges the cable inspection robot faces and the direction of future research.

This paper summarizes the research progress of the cable inspection robot and details the advantages and disadvantages of critical structures such as the external frame, intermediate adhesion device, attachment mechanism, driving method and safe return device of the robot. Finally, it points out the future direction of cable inspection robots, including lightweight design, hybrid design, multi-robot cooperative work, multi-technology integration and intelligent cable inspection digital twin model.

The cables are the main load-bearing components of a bridge, and their safety is crucial. However, subjected to varying loads and environmental influences over a long period, cables are prone to damage, threatening the bridge’s stability. Cable inspection robots can comprehensively detect and repair cable damage, significantly improving efficiency and safety.

This paper provides a comprehensive review of the current research on cable inspection robots, enabling readers to have a comprehensive and systematic understanding of the critical structures and key technologies of cable inspection robots and providing scientific references for researchers working on cable inspection robots.

Scholars mainly propose and establish theoretical models of cumulative fatigue damage for their research fields. This review aims to select the applicable model from many fatigue damage models according to the actual situation. However, relatively few models can be generally accepted and widely used.

This review introduces the development of cumulative damage theory. Then, several typical models are selected from linear and nonlinear cumulative damage models to perform data analyses and obtain the fatigue life for the metal.

Considering the energy law and strength degradation, the nonlinear fatigue cumulative damage model can better reflect the fatigue damage under constant and multi-stage variable amplitude loading. In the following research, the complex uncertainty of the model in the fatigue damage process can be considered, as well as the combination of advanced machine learning techniques to reduce the prediction error.

This review compares the advantages and disadvantages of various mainstream cumulative damage research methods. It provides a reference for further research into the theories of cumulative fatigue damage.