Modeling and Simulation on the Underwater Trajectory of Non-Powered Vehicle Discharged from the Broadside

In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater,the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching,the non-powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process,and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.

Study on Air-Purifying Performance of Semi-Flexible Asphalt Samples Coated with Titanium Dioxide Using Different Methods

Titanium dioxide(TiO_(2))was recently employed to apply onto road surfaces to degrade the harmful compounds from vehicle emissions.However,it remains a challenging task to find a highly compatible pavement type for TiO_(2)application to achieve durable and efficient air-purifying performance.This study proposed to coat TiO_(2)particles onto semi-flexible pavement surface and tried to investigate an optimum coating method.Three coating methods,including direct mixing TiO_(2)(MT)with asphalt mixture,spraying dry TiO_(2)(ST)coating and watersolution-based TiO_(2)(WT)coating on semi-flexible pavement surface.To achieve this objective,semi-flexible samples were prepared to evaluate and compare the performances of three coating methods by employing resistance to wearing,NO removal efficiency tests and residual texture depth tests.It was found that the ST method not only provided better NO degrading efficiency but also improved the resistance to wearing than the other two methods.

Multi-Attribute Group Decision-Making Method under Spherical Fuzzy Bipolar Soft Expert Framework with Its Application

Spherical fuzzy soft expert set(SFSES)theory blends the perks of spherical fuzzy sets and group decision-making into a unified approach.It allows solutions to highly complicated uncertainties and ambiguities under the unbiased supervision and group decision-making of multiple experts.However,SFSES theory has some deficiencies such as the inability to interpret and portray the bipolarity of decision-parameters.This work highlights and overcomes these limitations by introducing the novel spherical fuzzy bipolar soft expert sets(SFBSESs)as a powerful hybridization of spherical fuzzy set theory with bipolar soft expert sets(BSESs).Followed by the development of certain set-theoretic operations and properties of the proposed model,important problems,including the selection of non-powered dam(NPD)sites for hydropower conversion are discussed and solved under the proposed approach.These problems mainly focus on the need for an efficient tool capable of considering the bipolarity of parameters,complicated ambiguities,and multiple opinions.Supporting the new approach by a detailed comparative analysis,it is concluded that the proposed model is more comprehensive and reliable for multi-attribute group decisionmaking(MAGDM)than the previous tools,particularly considering the bipolarity of parameters under SFSES environment.

Protective performance test and safety risk evaluation of a powered air-purifying suit

The positive pressure biological protective suit is the highest degree of personal protective equipment, and its performance directly impacts the health and safety of the wearer. Protection factor is the most critical measure of the performance of a positive pressure bio-protective suit. This study establishes a dynamic detection system for the positive pressure bio-protective suit, to evaluate its safety risks, and explores methods to reduce these risks. A manikin was used to perform human actions, such as raising the arms, sitting, and walking, that were simulated at different levels. Integrity breaches of different shapes and sizes were made to different parts of the suit for evaluation. The aerosol concentration and the pressure of the suit were detected. Positive-pressure suits provide exceptionally good protection even in accident scenarios and provide a greater flexibility and more ergonomic benefits. However, sufficiently large (>3 cm) breaches caused a negative-pressure and an inward airflow during vigorous activities. The location of the breach site on the suit also had a significant effect on bio-aerosol leakage. Studies have shown that effective methods to avoid the risk of damage include increasing the air supply flow and performing gentle movements while wearing the suit. The dynamic detection method and the results obtained in this study are a significant advance to predict and avoid the risks associated with powered air-purifying suits.