Investigation of Automotive LiDAR Vision in Rain from Material and Optical Perspectives.

With the emergence of autonomous functions in road vehicles, there has been increased use of Advanced Driver Assistance Systems comprising various sensors to perform automated tasks. Light Detection and Ranging (LiDAR) is one of the most important types of optical sensor, detecting the positions of obstacles by representing them as clusters of points in three-dimensional space. LiDAR performance degrades significantly when a vehicle is driving in the rain as raindrops adhere to the outer surface of the sensor assembly. Performance degradation behaviors include missing points and reduced reflectivity of the points. It was found that the extent of degradation is highly dependent on the interface material properties. This subsequently affects the shapes of the adherent droplets, causing different perturbations to the optical rays. A fundamental investigation is performed on the protective polycarbonate cover of a LiDAR assembly coated with four classes of material-hydrophilic, almost-hydrophobic, hydrophobic, and superhydrophobic. Water droplets are controllably dispensed onto the cover to quantify the signal alteration due to the different droplets of various sizes and shapes. To further understand the effects of droplet motion on LiDAR signals, sliding droplet conditions are simulated using numerical analysis. The results are validated with physical optical tests, using a 905 nm laser source and receiver to mimic the LiDAR detection mechanism. Comprehensive explanations of LiDAR performance degradation in rain are presented from both material and optical perspectives. These can aid component selection and the development of signal-enhancing strategies for the integration of LiDARs into vehicle designs to minimize the impact of rain.

Economic and environmental impact assessments of a newly designed energy system for marine applications.

Marine transportation via the world's oceans is a critical way to convey goods and fuels between continents that cannot be performed cost-effectively by any other means. However, big ships heavily rely on fossil fuels, aggravating global carbon emissions. A key resolution to this dilemma is to employ clean fuels to reduce carbon emissions. This research paper introduces a new hybrid compound marine engine comprising a gas turbine, a solid oxide fuel cell, and a steam Rankine cycle. Three types of analyses, such as exergy, exergoeconomic, and exergoenvironmental analyses, are conducted on this proposed engine. It is found that the engine can produce a power of 15.5 MW, which is more than 48% compared to the traditional marine engine power, and the engine performance has up to 61% energy efficiency and 43% exergy efficiency. However, the exergetic efficiency of this engine based on fuel and product principal is 60%, which is more than 17% compared to its exergy efficiency. This engine has a 218 $/h Levelized cost rate and 139 mPt/h environmental rate. Finally, the average overall specific product exergy cost and environment are obtained to be 59 $/GJ and 20 mPt/MJ. By comparing five fuel blends, methane and hydrogen are the most economical and have the least impact on the environment; the second option is ethanol blend.

A comparative life cycle assessment of a cascade heat pump and a natural gas furnace for residential heating purposes.

A cascade heat pump is proposed as an environmentally friendly alternative to natural gas heating systems used for space heating in the residential sector. A comparative life cycle assessment of a natural gas furnace and a cascade heat pump was conducted to show the reductions in environmental impacts, such as global warming potential, energy used, and cost savings. The analysis used environmental data from 2020 for Toronto, Ontario, Engineering Equation Solver, and Sustainable Minds. The results of this comparative assessment demonstrate that implementing a cascade heat pump for heating purposes reduces the global warming potential by 85.4% when compared to a typical natural gas furnace. Moreover, the negative impacts on human health are reduced in every category. Specifically, the factors that can cause harm to human respiratory systems are decreased by almost 10 times when using the cascade heat pump as an alternative heating system. This is important since such systems are used in high density residential areas where the impact on human health can be far greater. Lastly, it is found that the highest CO2 -equivalent emissions are released during the usage life cycle stage in both heating systems at 18 883 kg of CO2 -equivalent, and 104 CO2 -equivalent for the furnace and heat pump, respectively. The cascade heat pump releases approximately 1% of carbon emissions than the emissions released by currently used heating systems, which are natural gas furnaces. Integr Environ Assess Manag 2022;18:572-580. © 2021 SETAC.

Analysis of ebike dynamics and cyclists' anxiety levels and interactions with road vehicles that influence safety.

The significance of commuting with ebikes as an integral part of the urban mobility of the future can no longer be ignored. The real and perceived hazards of cycling in urban areas and sharing roads with other motorized vehicles have been identified as a major barrier to wider adoption of ebikes. The objective of this study is to investigate parameters that affect the anxiety level of cyclists, which influences their safety and interaction with other road users. An ebike was instrumented with a variety of sensors and equipment to monitor the speed, balance of bike, type, and proximity of vehicles overtaking cyclists, as well as the events on the road. Thirty-two participants rode the instrumented ebike for 12 km on urban roads in Oshawa, ON, Canada. Participants wore a heart rate sensor attached to their chest and a helmet equipped with a peripheral detection task setup to measure stress and mental workload. This naturalistic study showed that most participants had concerns about the threats and risks of crashes when sharing the road with other vehicles. The data showed that the significant difference in acceleration between ebikes and conventional bikes does not change the perception of safety for cyclists. Additionally, the outcomes indicate that mental workload and average heart rate increase at lower speeds when passing a queue of vehicles in traffic or at intersections. Across all participants, the balance of the bike did not change significantly. Also, neither the heart rate nor mental workload showed a significant effect on the balance of the bike. This study suggests that dense traffic in the afternoon and the demands of riding a bike in complex traffic conditions result in a higher mental workload even though cyclists slowed down their speeds. Furthermore, the majority reported perceived risks of cycling on a shared road with other vehicles regardless of the demographic differences. The findings from this study can be used as a framework for the development of active safety features for ebikes.

Assessment of effectiveness of optimum physical distancing phenomena for COVID-19.

Currently, COVID-19 is a global pandemic that scientists and engineers around the world are aiming to understand further through rigorous testing and observation. This paper aims to provide safe distance recommendations among individuals and minimize the spread of COVID-19, as well as examine the efficacy of face coverings as a tool to slow the spread of respiratory droplets. These studies are conducted using computational fluid dynamics analyses, where the infected person breathes, coughs, and sneezes at various distances and environmental wind conditions and while wearing a face-covering (mask or face shield). In cases where there were no wind conditions, the breathing and coughing simulations display 1-2 m physical distancing to be effective. However, when sneezing was introduced, the physical distancing recommendation of 2 m was deemed not effective; instead, a distance of 2.8 m and greater was found to be more effective in reducing the exposure to respiratory droplets. The evaluation of environmental wind conditions necessitated an increase in physical distancing measures in all cases. The case where breathing was measured with a gentle breeze resulted in a physical distancing recommendation of 1.1 m, while coughing caused a change from the previous recommendation of 2 m to a distance of 4.5 m or greater. Sneezing in the presence of a gentle breeze was deemed to be the most impactful, with a recommendation for physical distancing of 5.8 m or more. It was determined that face coverings can potentially provide protection to an uninfected person in static air conditions. However, the uninfected person's protection can be compromised even in gentle wind conditions.