Design and Experimental Verification of Pressurized Cylinders in Hydraulic Rubber Hose Pressure Washers

Hydraulic rubber hoses are subject to great hydraulic impact during the actual working process, which causes a great potential safety hazard. Therefore, it is necessary to carry out pressure tests on hose assemblies to ensure its quality, so providing a high pressure for the hydraulic hose has become the key technology of this problem. Aiming at solving the problem of detection of pressure resistance in hydraulic rubber hose cleaning machines, this paper analyzed the pressurization mechanism of the hydraulic pressurized cylinder and proposed a method of continuous pressurization. This paper also theoretically analyzed the pressure expansion of the rubber hose, and the conclusion is that for the maximum hose capacity (hose size is Φ25 mm × 6 m), the volume of water required to provide water in the hose from 10 MPa to 100 MPa is 0.59 L. The pressurized cylinder was designed and checked theoretically and analyzed by the finite element method. It is concluded that the maximum stress of the pressurized cylinder is concentrated at the bottom of the high-pressure chamber, and the outlet hole at the bottom of the cylinder barrel of the high-pressure chamber is the weakest part of the pressurized cylinder. The performance of the supercharging cylinder is verified by experiments, which proves the feasibility, rapidity and stability of the supercharging cylinder.

Implementing and Monitoring the Use of Artificial Canopy Bridges by Mammals and Birds in an Indonesian Agroforestry Environment

Deforestation is a major threat to biodiversity, particularly within tropical forest habitats. Some of the fastest diminishing tropical forest habitats in the world occur in Indonesia, where fragmentation is severely impacting biodiversity, including on the island of Java, which holds many endemic species. Extreme fragmentation on the western part of the island, especially due to small-scale agriculture, impacts animal movement and increases mortality risk for mainly arboreal taxa. To mitigate this risk in an agroforest environment in Garut District, West Java, we installed 10 canopy bridges and monitored them through camera trapping between 2017 and 2019. Five of the monitored bridges were made of waterlines and five of rubber hose. We recorded Javan palm civets using the waterline bridges 938 times, while Javan slow lorises used the waterlines 1079 times and the rubber bridges 358 times. At least 19 other species used the bridges for crossing or perching. Our results demonstrate that relatively simple and cost-effective materials can be used to mitigate the effects of habitat fragmentation. We also recommend the use of camera traps to monitor the effectiveness of these interventions.

Analytical modeling for offshore composite rubber hose with spiral stiffeners under internal pressure

Internal pressure is the most important functional load for the offshore composite rubber hose. In this paper, the stress and radial displacement of the hose under internal pressure are investigated. The hose dimensions are length of 10.7 m and nominal bore diameter of 500 mm. The composite structure is mainly composed of cord-rubber reinforcement layers and a spiral steel stiffener. To calculate the stress and deformation of the hose, the stiffener and composite cord-rubber layers are theoretically analyzed based on the Euler–Bernoulli beam theory and the Donnell shell theory, respectively. The stiffener distinguishes the hose from common filament wound un-stiffened composite pipes in regard to the stress distribution and radial deformation. It is found that the stiffener plays an important role in affecting the mechanical behavior of composite reinforcement. Influences of the cord-winding angle, the stiffener spacing, and the stiffener’s tensile stiffness on the axial, hoop and shear stresses, and the radial displacement are investigated. The analytical model shows a good agreement with the finite element model. It is supposed to be of significant reference for practical engineering.

Unveiling the trap-nesting bees and wasps’ fauna (Hymenoptera: Apocrita) and associated organisms of the Jardim Botânico do Rio de Janeiro, Brazil

Urban areas, as cities, are frequently overlooked as refuges for the native fauna. However, these places may support several species and house relevant biodiversity contributing to important ecosystemic functions. Wasps and bees (Hymenoptera: Apocrita) are important faunistic elements acting as predators/parasitoids and pollinators, respectively. Therefore, they must be surveyed and inventoried for conservation purposes, especially in cities located in the Atlantic Forest domain, a ravaged Brazilian biome. Accordingly, this study presents a species list of trap-nesting bees and wasps that occurs at the Jardim Botânico do Rio de Janeiro. The survey was conducted using the trap-nest method. Three types of trap-nests were offered totalizing 1,038 traps: rubber hose, bamboo cane and plastic straw. The plastic straw traps were the most effective followed by the bamboo cane ones at attracting nesting wasps and bees. Between April/2017 and February/2019, 12 foundress species built nests: Tetrapedia curvitarsis (Apidae) (33 nests), Hylaeus sp. (Colletidae) (6), Auplopus cf. rufipes (Pompilidae) (5), Trypoxylon sp. (Crabronidae) (4), Pachodynerus nasidens (Vespidae) (3), Auplopus cf. brasiliensis (Pompilidae), Megachile benigna and Megachile sp. (Megachilidae), Euglossa pleosticta, Euglossa sp., and Eufriesea sp. (Apidae) and Penepodium sp. (Sphecidae) all with one nest. Also, four natural enemies were recorded: Chaenotetrastichus neotropicalis (Eulophidae), Gasteruption brachychaetum (Gasterupteiidae), Caenochrysis crotonis (Chrysididae) and Amobia sp. (Diptera: Sarcophagidae). Most bee nests were restrained to the matrix forest and nearby areas, whereas wasps built their nests predominantly in open areas. Regarding seasonality, bees tended to nest in the summer and early autumn influenced by mean temperature, in contrast of wasps that nested in late autumn, winter and spring, influenced by pluviosity. Besides many rare species, which suggests environmental disturbance, the Jardim Botânico do Rio de Janeiro showed a fairly diverse fauna and shows how forest fragment in cities may harbour important representatives of the native fauna.

Study on theoretical model of burst pressure of fiber reinforced arc-shaped rubber hose with good balance performance

This paper focus on the optimum design of the arc-shaped rubber hose, so that the hose has a good balance performance and a higher burst pressure. Based on the thin shell theory without considering bending moments and shear force, the equilibrium equation was established to obtain the internal force of the arc-shaped hose under internal pressure, and the burst pressure of the arc-shaped rubber hose was obtained by using Tsai-Hill failure criterion. According to the mechanical model of burst pressure, the influence of structural parameters on the burst pressure and distribution of vulnerable positions of arc-shaped rubber hose was studied. Then, in order to determine the structural parameters of the hose satisfying the balance performance, the deformation of the arc-shaped rubber hose was divided into two stages, including braiding angle deflection and tensile deformation of fiber, and the mechanical model of balance performance of the arc-shaped rubber hose was established. Eventually, on the basis of satisfying the balance performance of the hose, the hose was optimized for higher burst pressure. The correctness of the theoretical model and the optimization results were verified by experiments.

Study on Mechanical Model of Balance and Stiffness Characteristics of Fiber Reinforced Bellows Type Rubber Hose

The mechanical model related to the balance and stiffness characteristics of the bellows type rubber hose under internal pressure was studied. Based on the thin shell theory without considering bending moments and shear force, the equilibrium equation of the bellows type hose was established to obtain the mechanical equilibrium angle under different mechanical environments. Considering the deformation characteristics of the rope structure and the mechanical equilibrium angle of the hose, the deformation of the bellows type rubber hose was divided into two stages, including winding angle deflection and tensile deformation of fiber. Then the constitutive model of anisotropic material was introduced, and the physical equation of the bellows type hose was established to obtain the mechanical model of the balance and stiffness characteristics. According to the mechanical model, the influence of initial fiber winding angle, fiber layer thickness, the radius at the two ends of the hose, the length of hose, the curvature radius and internal pressure of hose on the balance and stiffness characteristics of hose was studied. Eventually, the structure of the hose was designed based on the mechanical model, to optimize the balance and stiffness characteristics of hose. The balance and stiffness characteristics of the optimized hose were verified by experiments. The theoretical and experimental results indicated that, the mechanical model of the balance and stiffness characteristics of the hose can be the theoretical basis for the optimization of structural parameters.