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In the daily operation of liquefied petroleum gas service, gas providers visit customers and replace cylinders if the gas is about to run out. The plans should both prevent gas shortages and realize the minimum working time. Existing research has two limitations: the absence of a comprehensive system and the difficulty of solving large-scale problems. In the former limitation, existing research tackled the partial problems of making plans for cylinder replacement, such as planning delivery routes given gas consumption forecast or determining the customers for visiting without obtaining the route. It does not consistently achieve gas shortage prevention and short working hours even when combining individual optimal methods. In the latter limitation, most existing studies have difficulty solving the problem within a reasonable time if there are many customers. This is because they simultaneously determined the customers for visiting and route planning by preparing binary variables representing customer-to-customer travel. In this study, we construct a comprehensive and practical system from gas consumption forecast to determine delivery routes for cylinder replacement with large-scale customers. To address these challenges, our method takes two steps: determining which customers to visit within several days and a single-day route. Moreover, we mitigate gas shortages among customers with poor forecast performance by considering the uncertainty of the gas consumption forecast. A field test involving over 1000 customers in Japan confirmed that the system is operationally viable and capable of preventing gas shortages and realizing short working time.

Based on the classical grid theory and related regulations, a structure model of a fiber-wound composite gas cylinder was designed in this paper. Based on the design results, a finite element model of a fully wound composite cylinder of an aluminum alloy inner liner with a working pressure of 35 MPa was established based on the ABAQUS software, and its stress distribution under working pressure and minimum burst pressure was analyzed. According to engineering experience, the pressure tolerance of composite cylinders can be improved by proper autofrettage pressure before working pressure, so the influence of autofrettage pressure was analyzed in this paper. The optimum autofrettage pressure was selected by setting the autofrettage gradient, and damage analysis was carried out on the cylinder with nominal working pressure of 35 MPa based on the Hashin failure criterion. The results show the initial damage sequence: matrix stretching occurs before the fiber stretching, and the damage generally starts from the spiral-wound layer. The tensile damage first appears in the transition section between the head and the barrel body, and the damage of the spiral-wound layer develops from the inner layer of the wound layer to the outer layer, while the damage of the circumferentially wound layer develops from the outer layer to the inner layer.

Since COVID-19 was declared as a pandemic by World Health Organization in March 2020, 169,682,828 cases have been reported worldwide, with 151,416,570 recovered, and 3,526,647 deaths by May 28, 2021. Oxygen gas cylinders demand is booming globally due to its need for COVID-19’s for intensive care. Thus, it is critical for hospitals to know exactly the time of receiving oxygen gas cylinders since this will help in minimizing the fatality rate. In this regards, this paper proposes a Multilayer Perceptron Neural Network-based model to predict the delivery time of oxygen gas cylinders for a real-life logistics data from a company that delivers oxygen gas cylinders to all cities around Saudi Arabia. Besides, Multilayer Perceptron Neural Network is benchmarked to supported vector machine and multiple linear regression. Although all the considered models have the ability to provide accurate prediction results, the findings indicate that the proposed supported vector machine and Multilayer Perceptron Neural Network model provide better prediction results. The analysis was achieved through a methodology to identify factors with the highest impact and build a neural network model. The model was further optimized to identify the best order and select the best subset of input variables. The analysis showed that the neural network model can be used effectively to estimate the delivery time of oxygen gas cylinders. The model illustrated high accuracy of prediction by comparing the predicted values to the actual values.

For the \"thin walled and thick nozzle\" high-pressure gas cylinder liner cannot be molded as a whole this problem, this paper puts forward a new technology route. A composite process based on thickening of the end and neck-spinning was designed. Through the finite element simulation to analyze the neck-spinning of the gas cylinder liner, the distribution law of equivalent stress and strain in the neck area after different passes of forming was investigated; the axial distribution of the three-way strain in different thickness layers is further discussed, and the influence laws of different process parameters on the equivalent stress and strain are derived and analyzed; the process parameters are also optimized and the optimal set of process parameters based on equivalent stresses and thickening factor is derived. The spinning experiments successfully produced a \"thin walled and thick nozzle\" monolithic cylinder liner, and compared with the simulation results to verify the accuracy of the model.

Type IV gas cylinders are widely used in the field of vehicles due to their advantages such as light weight, cleanliness, and low cost. Ramie fiber/degradable epoxy resin composites (RFRDE) provide new ideas for the material selection of Type IV gas cylinders due to their advantages of low carbon emissions, low environmental pollution, and renewable resource utilization. However, the poor interfacial bonding strength and moisture resistance between polyethylene plastics and RFRDE have limited their application areas. This study tested the mechanical properties of ramie fibers at different heat treatment temperatures, and studied the thermal mechanical properties of RFRDE through differential scanning calorimeter and curing kinetics methods. At 180 °C, the tensile strength of fiber bundles decreased by 34% compared to untreated fibers. As the highest curing temperature decreases, the tensile strength of RFRDE increases but the curing degree decreases. At the highest curing temperature of 100 °C, the tensile strength of RFRDE is 296 MPa. The effect of the corona discharge and flexible adhesive on the surface modification of polyethylene was analyzed using scanning electron microscopy. These results provide guidance for the development of natural fiber/degradable epoxy resin composite materials.

An integral manufacturing process with hot drawing and cold flow forming was proposed for large-diameter seamless steel gas cylinders. The main purpose of this study was to find out the effects of the manufacturing process on the microstructure and mechanical properties of gas cylinders made of 34CrMo4 steel. Two preformed cylinders were produced by hot drawing. One cylinder was then further manufactured by cold flow forming. The experiments were carried out using three types of material sample, namely, base material (BM), hot drawing cylinder (HD), and cold flow-formed cylinder (CF). Tensile and impact tests were performed to examine the mechanical properties of the cylinders in longitudinal and transverse directions. Microstructure evolution was analyzed by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) to reveal the relation between the mechanical properties and the microstructure of the material. It is found that the mechanical properties of the 34CrMo4 steel gas cylinders were significantly improved after hot drawing and flow forming plus a designed heat treatment, compared with the base material. The observations of microstructure features such as grain size, subgrain boundaries, and residual strain support the increase in mechanical properties due to the proposed manufacturing process.

Refillable seamless steel gas cylinders are widely used to store and transport clean energy, such as compressed natural gas (CNG) and hydrogen. Conventional manufacturing processes have some disadvantages which bring potential hazard for the safety and reliability of cylinders. After reviewing the conventional manufacturing processes, a hot deep drawing process is recommended with solid steel billet stock. Based on this, an integral manufacturing process with cold flow forming process is proposed for large-diameter seamless steel gas cylinders to improve the performance of gas cylinders. Several cylinder properties including size error and fatigue lives are compared. The uniformity of wall thickness is further improved for gas cylinders by the integral process. The gas cylinders obtain fine surface finish, high tolerance of size, and commensurately enhanced fatigue lives. Meanwhile, the failure mode and effect analysis (FMEA) method is adopted to study the reliability of steel gas cylinders. The reliability of steel gas cylinder with cold flow forming process is compared with the conventional processes. The probabilities of most causes are ameliorated, except for the lamination that is usually resulted from wrong flow forming process parameters, e.g., high reduction rate and feed rate. As a whole, there is a marked drop in the risk priority number of the integral process. It is worth to further spread this in gas cylinder industry.

Seamless gas cylinders for diving exhibit excellent low-temperature impact performance, lightweight characteristics, and good corrosion resistance, making them widely applicable in underwater activities. However, during use, the peeling of paint or corrosion on the surface of these cylinders poses a significant threat to their safety. In this study, environmentally friendly arc ion plating technology was used to deposit TiBN, CrAlN, and nano-multilayer coatings of CrAlN/TiBN. The surface morphology, tribological properties, and corrosion resistance of these coatings were investigated. The results indicated that both CrAlN and CrAlN/TiBN coatings possess fewer droplets, pinholes, and pits, and the cross-section of the CrAlN/TiBN coating exhibits a denser structure. The preferred orientation for TiBN was identified as TiB2 (101), while that for CrAlN was Cr(Al)N (200), with the preferred orientation for CrAlN/TiBN being TiB2 (101). The friction measurements revealed that the lowest coefficient was observed in the CrAlN/TiBN coating (0.489), followed by CrAlN (0.491) and then TiBN (0.642). Electrochemical tests conducted in artificial seawater demonstrated that the self-corrosion potential was highest for the CrAlN/TiBN coating, followed by CrAlN and lastly TiBN. The developed TiBN-based nano-multilayer coatings hold substantial application value in protecting seamless gas cylinders used in diving.

Filament winding reinforcement is often applied to fulfill high-pressure resistance and is lightweight for gas cylinder productions. This article analyzes the winding pattern and the corresponding characteristics for filament winding cylinders based on the resulting thickness and strength such that the gas cylinders can be made as light as possible. In order to prevent the sliding between the filament material and the cylinder surface during the winding process, a range of winding angles that do not exceed the maximum static friction at every instant is adopted. The gas cylinder geometric structure formed by a complete round of winding using different winding angles is calculated to find the winding pattern that consumes the least composite filament. The winding pattern can also be determined before production to reduce the cost and time for customized products. By sequential contact points of the winding process, motion planning can be carried out for a four-axis filament winding machine.