In order to improve fruit yield, girdling technology is widely used in fruit production. However, in the practice of Hui jujube planting in Southern Xinjiang, it was found that the jujube fruit quality declined and the health problems and death rate of jujube trees increased after jujube trees have been girdled continuously for many years, which seriously affected the economic benefits of jujube planting. So, this study was carried out to explore the specific influence law of continuously jujube-tree girdling for many years on the main nutrients (soluble solid, protein, total acid, vitamin C, total sugar, fat and so on), physical quality attributes (single-fruit weight, hardness and geometric-mean diameter) of jujube fruit and tree health. Through the detection of the nutrients of jujube fruit, it was found that the long-term girdling of jujube trees significantly reduced the main nutrients of jujube fruit. The total sugar and reducing sugar content of jujube-fruit samples from the trees without girdling were 134.23% and 109.62% of the corresponding indexes of jujube-fruit samples from girdled ones, respectively; furthermore, the sugar–acid ratio of jujube samples from the girdled trees was 149.95, while the sugar–acid ratio of fruit from non-girdled trees reached 183.78. Moreover, the protein content of fruit from non-girdled trees was 5.91% higher than that of fruit from girdled ones. In addition, the single-fruit weight, hardness and geometric-average diameter of jujube from non-girdled jujube trees were 20.25%, 13.31% and 20.21% higher than those of jujube from girdled ones, respectively. Moreover, microstructural analysis of the callus and the newly formed phloem showed that the adverse effects of girdling on the phloem function were persistent and permanent. It was also found that jujube-tree girdling can also cause damage, to a certain extent, to the xylem around the girdling wound. The above research results further explained the internal cause of jujube-tree death caused by long-term continuously jujube-tree girdling. The results of this study can provide some scientific basis for the effective application of fruit-tree-girdling technology in fruit production.

The old drip irrigation belts in Xinjiang cotton fields are prone to damage and have low recovering efficiency when being mechanically recovered, as well as poor mechanical performance and short service life of the old materials used in the production of various new products. Therefore, experiments were carried out from the macroscopic mechanical properties and microscopic chemical composition changes of the old drip irrigation belt to explore how the changes in its mechanical and chemical properties affect the recovery and recycling of the old drip irrigation belt. Mechanical properties of the old drip irrigation belts were tested by statics and dynamics test methods. The experiment results of indicators about mechanical properties showed that the tensile strength, elongation at break, natural rebound rate, impact strength and other mechanical parameters of the old drip irrigation belt samples were significantly lower than the corresponding values of the new ones. Which will affect the tensile capacity of the drip irrigation belt when it is recovered in the field. Furthermore, X-ray energy spectrum and infrared spectrum methods were used to analyse the chemical composition changes of the old drip irrigation belt. The determination results of X-ray energy spectrum showed that the oxygen content of the new drip irrigation belt samples was 1.73%, while that of old drip irrigation belt samples reached 12.15% ~ 15.27%. Then, the infrared spectrum experiment results showed that there were significantly more carbon groups in the old drip irrigation belt samples than that in the new ones. In addition, the correlation between the mechanical properties and oxidation degree of drip irrigation belt samples was analyzed, results showed that there was a significant negative correlation between them. This study results can provide basic data and theoretical guidance for the research and development of drip irrigation belt recovery equipment in Xinjiang cotton field, the research of rapid detection method of drip irrigation belt aging, the manufacture of anti-aging drip irrigation belt and the cyclic utilization of old materials.

Girdling is an important means of improving the yield and quality of jujube trees, but this measure can easily cause injury, or even death, to jujube trees. A technology for increasing yield and improving quality, based on local thermal damage of jujube bark, is proposed to address a series of issues in current jujube-tree-girdling technology. First, we measured the thermophysical parameters of jujube bark and established a heat-transfer model for jujube bark. Then, in order to investigate the impact of local thermal damage on jujube-tree yield and fruit quality, local heating experiments were conducted on jujube-tree bark, using the heat-transfer model. The experimental results indicated that heating the jujube bark at a certain temperature for an appropriate time can effectively improve the yield and quality of jujube fruit. Compared with traditional girdling techniques, this method has less impact on the health of jujube trees and does not form permanent wounds on them. The research results provide new ideas for exploring sustainable yield-increase methods for fruit trees.

Jujube girdling is an important method to improve the yield and quality of jujube fruit. However, girdling usually causes the tearing of jujube bark, resulting in the slow healing and even death of jujube trees. These problems directly affect the economic benefits of jujube planting. In this paper, in order to reveal the tearing mechanism of jujube bark caused by girdling, and provide the basic mechanical parameters of jujube bark for the research and development of automatic girdling equipment, the structure and mechanical characteristics of jujube bark were studied through theory and experimental methods. The results of microscopic observation showed that jujube bark is a biological composite material mainly composed of the phloem, periderm and epidermis. Furthermore, a mathematical model-based analysis of the growth stress of jujube bark showed that growth stress can be regarded as a biaxial stress state, which can promote the longitudinal tearing of jujube bark during girdling. The tensile test results of jujube bark showed that jujube bark belongs to the category of anisotropic and biologic material. Its longitudinal and transverse mechanical characteristics are significantly different. The maximum longitudinal tensile load was in the range of 105.9~293 N, the longitudinal tensile strength was 16.3 MPa and the elastic modulus was 255.6 MPa. The average transverse tensile load was only 27.9% of the longitudinal tensile load. The transverse tensile strength was 3.5 Mpa and its elastic modulus was 724.14 MPa. The transverse cutting test of jujube bark showed that the average cutting force was 118.2 N and the cutting strength was 9.8 MPa. The results of this study showed that both the growth stress and the anisotropic natural polymer of jujube bark have adverse effects on girdling. Subsequently, issues relating to the selection of appropriate girdling tools and the matters needing attention in the process of the girdling operation were proposed, so as to guide the correct application of girdling technology. In addition, some suggestions on the research and development of girdling tools in the future are put forward.

National Undergraduate Engineering Training Integration Ability Competition is essential in Chinese engineering colleges. Among these items, the carbon-free car competition is popular among college students because of its flexible track, challenging design tasks, and fair judging criteria. In this study, to design a reasonable carbon-free car structure according to the track given by the competition, a reverse analysis method was proposed for the double 8-shaped carbon-free car trajectory based on the space cam mechanism. First, the carbon-free car’s structure was designed, and its stress state was analyzed, with the results indicating that the driving force should be reduced as much as possible under the premise of satisfying the starting requirements to increase the travel distance of the carbon-free car with no slipping. Then, the function between the car track and the front wheel swing angle was established, and the displacement law of the push rod of the cam mechanism was calculated through the swing angle of the front wheel. Finally, the cam profile was got based on the operating law of the push rod. Research has shown that compared with the traditional forward design, this method was more accurate with strong feasibility and operability, which provided good technical support for designing the subsequent carbon-free car competition.

Drip irrigation technology is widely used in agricultural production in the Xinjiang region. However, there are still a series of problems in the mechanized recovery of field drip irrigation belts, such as easy breakage of drip irrigation belts, low recovery efficiency, and excessive doping of recycled drip irrigation belts. This study focused on the problems of mechanized recovery of drip irrigation belts in Xinjiang and designed a new type of drip irrigation belt recovery machine. The key mechanisms of the new drip irrigation belt recovery machine were designed and theoretically analyzed, and their basic parameters were determined. Then, the superiority of the new drip irrigation belt recovery machine’s operational performance was verified through experiments. The experimental results showed that the new drip irrigation belt recovery machine is superior to existing machines in terms of the drip irrigation belt recovery rate and operational efficiency. In addition, the drip irrigation belts recovered by the newly designed machine have low impurity content. During the recovery process, the new machine requires less labor input than that of the existing machine.