Search results

The purpose of this paper is to design a climbing robot connected by a connecting rod mechanism to achieve multi-functional tasks such as obstacles crossing and climbing of power transmission towers.

A connecting rod type gripper has been designed to achieve stable grasping of angle steel. Before grasping, use coordination between structures to achieve stable docking and grasping. By using the alternating movements of two claws and the middle climbing mechanism, the climbing and obstacle crossing of the angle steel were achieved.

Through a simple linkage mechanism, a climbing robot has been designed, greatly reducing the overall mass of the robot. It can also carry a load of 1 kg, and the climbing mechanism can perform stable climbing. The maximum step distance of the climbing robot is 543 mm, which can achieve the crossing of angle steel obstacles.

A transmission tower climbing mechanism was proposed by analyzing the working environment. Through the locking ability of the screw nut, stable clamping of the angle steel is achieved, and a pitch mechanism is designed to adjust the posture of the hand claw.

High power rotating machinery requires large diameter bearings that can perform under extreme conditions. Vibrations and critical speeds of rotor supported by tilting pad journal bearing (TPJBs) exceeding their design limits may cause unit failure. This paper aims to investigate the experimental technique for large diameter bearings.

To obtain the experimental support for rotor-bearing system design, an experiment focusing on vibration monitoring is given. The sensors arrangement, monitoring system and critical speed identification method are provided.

By using test bench in factory unit, a large amount of vibrations data of different working situations is obtained. In addition, a method named non-excitation identification for critical speed is proposed. The critical speed of rotor identified through vibration data is given. The theoretical calculation results are also presented.

The basis for rotor-bearing system design can be obtained through comparisons between the experimental results and the theoretical calculation data.

This paper aims to automatically plan sequence for complex assembly products and improve assembly efficiency.

An assembly sequence planning system for workpieces (ASPW) based on deep reinforcement learning is proposed in this paper. However, there exist enormous challenges for using DRL to this problem due to the sparse reward and the lack of training environment. In this paper, a novel ASPW-DQN algorithm is proposed and a training platform is built to overcome these challenges.

The system can get a good decision-making result and a generalized model suitable for other assembly problems. The experiments conducted in Gazebo show good results and great potential of this approach.

The proposed ASPW-DQN unites the curriculum learning and parameter transfer, which can avoid the explosive growth of assembly relations and improve system efficiency. It is combined with realistic physics simulation engine Gazebo to provide required training environment. Additionally with the effect of deep neural networks, the result can be easily applied to other similar tasks.

The paper seeks to investigate the laser engineered net shaping (LENS) of metal thick‐wall parts from Ni‐based alloy powders.

The composition of Ni‐based alloy powders was determined from phase diagram, which was 84Ni14.4Cu1.6Sn. The powders were prepared by gas atomization. Deoxygenation and screen separation were applied to the powders to improve the sintering ability and narrow the particle size distribution before shaping. Thick‐wall metal parts were built by LENS under different conditions. The microstructures, surface morphologies of the prepared parts were characterized.

The gas atomized powders were almost uniformly spherical after sieving. Most of oxygen contained in the alloy powders could be removed in H₂ atmosphere for heating at 550°C for 2 h. These nickel‐based alloy powders with 150‐200 mesh size were suitable for powder feed system. And these powders were shaped successfully by LENS. Thick‐wall parts with thickness ranged from 20 to 25 mm were fabricated. The thickness of each layer was between 400 and 600 μm by scanning electron microscope. Metallographs revealed that dendritic structures with different characteristics were grown on XY‐, YZ‐ and XZ‐section.

The present experiments were limited by the atmosphere control during the LENS process. The oxide at the interface between two neighbor layers could decrease the mechanical properties if without good inert gas protection, such as a protective atmosphere chamber.

This paper describes a refined experimental program that is needed to resolve the remaining technical issues in LENS of thick‐wall parts. The nickel‐based alloy powders suitable for the LENS process were studied and prepared. After pretreatment, the self‐made powders have good shaping ability. Microstructure features were first discussed with the variation of the face orientation. The dendrite arm distance obtained by this experiment is between 8 and 20 μm, well conforming to the theory. The thick‐wall parts with dense structures were fabricated successfully to widen the field of application of LENS.

This paper aims to present the theoretical and experimental investigation of the temperature of high speed and heavy haul tilting pad journal bearing.

The bearing is 152.15 mm in diameter with three slenderness ratios (L/D) and three clearance ratios. The equations that govern the flow and energy transport are solved by the finite difference method, and the experimental tests are conducted in a test rig of high speed and heavy haul tilting pad journal bearing. The shaft speed ranges from 3,000 to 16,500 r/min (the highest linear-velocity equals 131.4 m/s), and the three static loads are 10, 20 and 30 KN.

The comparisons between numerical results and experimental results show better correlations. It is shown in the theoretical and experimental results that the temperature increases with static load and shaft speed and decreases with clearance ratio and L/D.

The theoretical models presented in this paper can be used to predict the temperature of tilting pad journal bearing when the shaft’s linear velocity is up to 130 m/s.

This study aims to examine the impact of logistics and merchant certification information on consumer behaviour in hybrid retail platforms. Furthermore, it explores the moderating role of online shopping experience on the certification effect.

The authors utilize transaction-level data from over 2.5 million consumers involving 30,000 stock keeping units (SKUs) on JD.com in March 2018. They analyse the impact of different types of certification information on consumer behaviour using ordinary linear regression and linear probability models.

The findings reveal that, compared with information without certification, (1) single logistics certification information can enhance consumers' search depth and purchase intention; (2) dual logistics and merchant certification information also has a positive impact on consumer behaviour; and (3) single certification information is more effective for inexperienced consumers, while dual certification is more effective for experienced consumers.

Theoretically, this study contributes to the literature on certification information in hybrid retail platforms and broadens information communication methods for online shopping. Our discovery is meaningful for managers in locating customers and allocating resources. In addition, we encourage online retailers to utilize certification information to engage consumer.

Hand, foot and mouth disease (HFMD) is a common infectious disease in infants and children. HFMD has caused millions of cases and a large epidemic worldwide. A number of studies have shown that the incidence of HFMD is closely related to various factors such as meteorological factors, environmental air pollution factors and socio-economic factors. However, there are few studies that systematically consider the impact of various factors on the incidence of HFMD. The paper aims to discuss these issues.

This study used grey correlation analysis and principal component analysis (PCA) method to systematically analyse the impact of meteorological factors, health resource factors, socio-economic factors and environmental air pollution factors on the incidence of HFMD in Shenzhen.

The incidence of HFMD in Shenzhen was affected by multiple factors. Grey correlation analysis found eight influencing factors which are as follows: volume of industrial waste gas emission; the days of air quality equal to or above grade; the volume of industrial nitrogen oxide emission; precipitation; the mean air temperature; the gross domestic product; the expenditure for medical and health care; and the gross domestic product per capita. PCA found that the gross domestic product, the volume of industrial soot emission, the relative humidity, and the days of air quality equal to or above grade have a higher load value.

This study is the one of the first studies that apply the grey correlation analysis to analyse the influencing factors of HFMD in the English literature, which to some extent fills up the blank in this field.

The purpose of this paper is to solve the azimuth sensitivity of a high-resolution range profile (HRRP), which is one of the biggest obstacles faced by a radar automatic target recognition (RATR) system.

Aimed at addressing the shortcomings of the equal angular-sector segmentation based on the scatterer model, an adaptive angular-sector segmentation is proposed on the basis of grey incidence analysis (GIA).

The main conclusions reached are as follows. First, the adaptive angular-sector segmentation in terms of GIA is suitable for RATR based on the HRRP; and, second, the adaptive angular-sector segmentation based on the type-B degree of grey incidence model is better than the Deng-Si degree of grey incidence model and the degree of grey slope incidence model.

The outcome obtained in this paper can be selected for the RATR application.

This paper has been built on the basis of previous research achievements, and a new RATR method of adaptive angular-sector segmentation is presented based on the GIA.

In this study, a novel glutathione (GSH) surface molecular imprinting polymer (SMIP) was successfully prepared by using macroporous adsorption resins (MAR) as substrate, which could separate and purify GSH efficiently.

SMIP was synthesized by chloromethylated modified MAR (LX1180-Cl) as the substrate, N, N’-methylenebisacrylamide (NMBA) as a crosslinker, GSH as a template, acrylamide (AM) and N-vinylpyrrolidone (NVP) as functional monomers. The morphology and structure of the polymer were characterized by scanning electron microscope and Fourier transforms infrared spectroscopy.

The maximum adsorption capacity toward GSH was 39.0 mg/g and the separation decree had relation to L-cysteine (L-cys) was 4.2. The optimal operation conditions were studied in detail and the got as follows: the molar ratios of NMBA, AM, GSH and NVP, were 7.0, 0.8 and 0.5. The optimal time and temperature were 14 h and 40°C, respectively. The Langmuir and pseudo-first-order model were fitting these adsorption characteristics well.

GSH has a diversity of medicinal and bioactive functions, so the purpose of this study representing a method in separate and purify technology of GSH, which provided a way for the development of medicine.

This contribution provided a novel way to separate GSH from L-cys. Under the optimal conditions, the maximum adsorption capacity toward GSH was 39.0 mg/g and the separation decree had relation to L-cys was 4.2.

There is explosive gas in many disaster environments. The conventional search and rescue robots are not allowed to work in these environments, since they may cause explosion. The purpose of this paper is to describe the design and development of the serpentine omnitread robot HITSR‐I for working in these areas.

HITSR‐I consists of four segments, and each segment is equipped with crawlers in the four directions. It can be operated even under the situation of sideslip without any recovering actions. There are pressed CO₂ containers and the pressurized control system inside the robot, and the shells of the robot are a fully sealed up structure. They can maintain the inside pressure higher than the outside. The robot can release the communication relay node to extend the communicating area, so it can search a large area even amid rubble.

HITSR‐I was developed with the capability of climbing over 400 mm high obstacles. The maximum travel distance was 315 m. The pressurized system could enable the robot to work in Zones 1 and 2.

Design and development of a serpentine robot which can work in hazardous areas containing explosive gas. It can travel for a long distance in ruins by releasing the communication relay nodes.