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Conventional electric heaters mostly use U-shaped electric heating tubes and the hollow tube electric heaters are new type ones that rely on the heat transfer tubes as heating elements. However, in the original design, the fluid flows through the annular gaps between the shell wall and the supporting plates, the chambers between supporting plates are generally stagnant zones. The purpose of study is to overcome these deficiencies.

A modified approach is proposed in which the heating tubes are surrounded by holes on the supporting plates, thus the stagnant flow zone can be eliminated and the heating surfaces of both inside and outside the tube can be fully used. Numerical simulations were carried out on four schemes of hollow tube electric heaters, i.e. plate blocked, countercurrent, parallel and split. The results show that the two schemes of parallel and split can reduce the temperature difference between the two sides of the fixed tube plate, and thus reduce thermal stress and prolong the service life.

The split scheme of electric heater has the highest comprehensive index, moderate heat transfer coefficient and minimum pressure drop on the shell side. Its average heat transfer coefficient and comprehensive index are, respectively, 15.7% and 52.9% higher and its average pressure drop and tube wall temperature are, respectively, 57.6% and 19 K lower than those of the original plate blocked scheme, thus it can be recommended as the best scheme of the hollow tube electric heaters.

Based on the original design of hollow tube electric heater with plate blocked scheme, three plate perforated schemes were proposed and investigated. The thermal and flow features of the four schemes were compared in terms of heat transfer coefficient, pressure drop and comprehensive index h_o·Δp_o^−1/3. The split scheme can reduce the temperature difference between two sides of the fixed tube plate with reduced thermal stress. It has moderate tube wall temperature and heat transfer coefficient, the smallest shell side pressure drop and the highest comprehensive index h_o·Δp_o^−1/3, and it can be recommended as the optimal scheme.

This paper aims to present a new friction-stir-weld robot for large-scale complex surface structures, which has high stiffness and good flexibility.

The robot system is designed according to manufacturability of large aluminum products in aeronautic and astronautic area. The kinematic model of the robot is established, and a welding trajectory planning method is also developed and verified by experiments.

Experimental results show that the robot system can meet the requirements of friction stir welding (FSW) for large-scale complex surface structures.

Compared with other heavy robotic arm and machine tool welding devices, this robot has better working quality and capability, which can greatly improve the manufacturability for large-scale complex surface structures.

The friction-stir-weld robot system is a novel solution for welding large-scale complex surface structures. Its major advantages are the high stiffness, good flexibility and high precision of the robot body, which can meet the requirements of FSW. Besides, a welding trajectory planning method based on iterative closest point (ICP) algorithm is used for welding trajectory.

China’s property industry in the past few years has made great progress and it is now vital to improve its management processes. Explains the traditional system of management for urban residential districts (urban living quarters) in China and the professional management pattern now becoming popular in the southern part of China. Comparing these two different management patterns, claims that the professional management pattern will sooner or later be adopted and accepted for all urban residential districts throughout China.

The purpose of the paper is to predict the residual life of liquid-storage tank to ensure safety and long-term service life of the structure.

The paper carried out the stress analysis of the wall plate and bottom plate of the liquid-storage tank, and the influence of circumferential stress on the tank is considered. On the other hand, considering the influence of the tank wall surface on the tank life, based on the Paris law, the surface processing coefficient and surface roughness coefficient are introduced to improve the Paris law.

The effectiveness of the improved model is verified by comparing with theoretical and experimental data, which provide a new method for the prediction of the remaining service life of the tank. Combined with the fatigue crack data in the test report and the calculated circumferential stress, the residual life of the storage tank is predicted.

The improved model provides a new method for the prediction of the remaining service life of the tank.

This study aims to verify the influence of chief executive officer (CEO) cognitive trust and governmental support on marketing innovation. Additionally, it evaluated the influence of CEO cognitive trust on the marketing innovation of small, medium and micro enterprises (SMMEs).

The authors empirically assessed the impact of CEO cognitive trust on SMME marketing innovation. Furthermore, the authors examined the mediating effect of governmental support on this relationship. The authors then studied a sample of 1,770 SMMEs in China by applying partial least squares structural equation modeling.

The authors found that CEO cognitive trust was negatively associated with marketing innovation. Moreover, governmental support has a competitive mediating effect on this relationship. Thus, while governmental support is urgently needed to enhance the marketing innovation of SMMEs, CEO cognitive trust negatively impacts this relationship.

This study empirically establishes the importance of CEO cognitive trust and governmental support as antecedents in SMME marketing innovation. This contributes to the knowledge base of the management field, adding to important streams in the wider business literature, such as marketing studies, leadership management, strategic management and innovation. While the model is parsimonious, the relationships it highlights are robust and can be generalized to other contexts.

Managers must not only have high levels of trust and authority but must also embody these characteristics rationally. Simultaneously, managers must actively establish a trusting relationship with the government, thereby improving their company’s ability to integrate government policy information while also actively seeking governmental support. These measures are helpful in enhancing the marketing innovation capabilities of SMMEs.

SMMEs occupy an important position in all countries’ economies and their vitality directly determines the strength of the economy. Formulating reasonable marketing strategies will help enhance market competitiveness and promote the rapid development of SMMEs.

The literature on marketing innovation has paid little attention to CEO cognitive trust, while CEOs’ cognitive characteristics are an increasingly relevant antecedent in SMME marketing innovation. This study analyzed CEO cognitive trust as a possible antecedent of marketing innovation activities in SMMEs, with this influence path being evaluated. This study extends the current knowledge in this field by considering the effects of CEO cognitive trust on marketing innovation.

As current university students may access information for their study anytime, anywhere with ubiquitous mobile technologies, this research re-examines the roles of study space in students' learning and campus life.

A survey was conducted to collect students' opinions and habits regarding the usage of different study spaces. Results in three different academic majors (science and engineering, arts and business) of a comprehensive international university were compared.

The authors’ findings showed a more diversified space usage among students, with the library café increasingly important in students' learning and life while learning commons remain important. However, there were only minor differences among these three study majors towards the learning and entertaining spaces, as these students generally apply inquiry-based learning.

While some researches have investigated students' usage of university and library learning spaces, few studies have focused on the study space issue in Hong Kong or other metropolises in the East under the current mobile learning environment. This study's insights could help libraries and universities improve the management of their physical spaces to meet student needs.

When processing 11Cr-3Co-3W martensitic heat-resistant steel, the traditional pouring cooling method often appears large cutting force, high cutting temperature, serious tool wear and poor surface quality. This paper aims to use new cooling methods for processing this problem.

Different performance indicators such as cutting force, tool wear and surface quality were measured and analysed under different continuous milling times. The relationship between liquid nitrogen flow and cutting force and surface roughness was analysed and measured.

The results show that with the increase of liquid nitrogen flow, the cutting force decreases, especially the Fx component, which decreases by 10%. When the liquid nitrogen flow reaches 8 L/min, the effect of increasing the liquid nitrogen flow on reducing the cutting force becomes smaller. The cutting force reduced by up to 15%, and the tool life increased up to 20% using liquid nitrogen cryogenic cooling than in cutting liquids cooling. When minimal quantities of lubricant (MQL) was added, the cutting force was reduced by 23%, and the tool life increased by 25%. When the cutting speed increases from 100 m/min to 250 m/min, the cutting force with cutting liquid cooling does not change significantly while the cutting force with liquid nitrogen cooling decreases with the cutting speed increasing. It shows that liquid nitrogen cooling is more suitable for high-speed machining. After the cutting length reaches 66 m, the surface roughness of the workpiece using liquid nitrogen cooling method larger than that of the cutting liquid cooling method. When MQL is added into liquid nitrogen, the lubrication performance is improved, and the surface roughness of the workpiece is reduced about 8%.

Many studies had focused on the improvement of tool life and surface quality by different cooling methods, or on the injection process and chip mechanism. However, there are few relevant studies on the variation of cooling and lubrication properties with the change of cutting length in liquid nitrogen cryogenic processing. In this research, different performance indicators such as cutting force, tool wear and surface quality were measured and analysed under different continuous milling times. The relationship between liquid nitrogen flow and cutting force and surface roughness was analysed and measured.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0053/

This paper aims to introduce an aircraft engine inspection robot (AEIR) which can go in the internal of the aircraft engine without collision and detect damage for engine blades.

To obtain the position and pose information of the blades inside the engine, a novel tactile sensor based on electrical impedance tomography (EIT) is developed, which could provide location and direction information when it contacts with an unknown object. In addition, to navigate the continuum robot, a control method is proposed to control the continuum robot, which can control the continuum robot to move along the pre-planned path and reduce the deviation from the planned path.

Experiment results show that the average error of contact location measurement of the tactile sensor is 0.8 mm. The average error relative to the size (diameter of 18 mm) of the sensor is 4.4%. The continuum robot can successfully reach the target position through a gap of 30 mm and realize the spatial positioning of blades. The validity of the AEIR for engine internal blade detection is verified.

The aero-engine inspection robot developed in this paper can replace human to detect engine blades and complete different detection tasks with different kinds of sensors.

In the past few decades, the content-based image retrieval (CBIR), which focuses on the exploration of image feature extraction methods, has been widely investigated. The term of feature extraction is used in two cases: application-based feature expression and mathematical approaches for dimensionality reduction. Feature expression is a technique of describing the image color, texture and shape information with feature descriptors; thus, obtaining effective image features expression is the key to extracting high-level semantic information. However, most of the previous studies regarding image feature extraction and expression methods in the CBIR have not performed systematic research. This paper aims to introduce the basic image low-level feature expression techniques for color, texture and shape features that have been developed in recent years.

First, this review outlines the development process and expounds the principle of various image feature extraction methods, such as color, texture and shape feature expression. Second, some of the most commonly used image low-level expression algorithms are implemented, and the benefits and drawbacks are summarized. Third, the effectiveness of the global and local features in image retrieval, including some classical models and their illustrations provided by part of our experiment, are analyzed. Fourth, the sparse representation and similarity measurement methods are introduced, and the retrieval performance of statistical methods is evaluated and compared.

The core of this survey is to review the state of the image low-level expression methods and study the pros and cons of each method, their applicable occasions and certain implementation measures. This review notes that image peculiarities of single-feature descriptions may lead to unsatisfactory image retrieval capabilities, which have significant singularity and considerable limitations and challenges in the CBIR.

A comprehensive review of the latest developments in image retrieval using low-level feature expression techniques is provided in this paper. This review not only introduces the major approaches for image low-level feature expression but also supplies a pertinent reference for those engaging in research regarding image feature extraction.