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In the architecture of an Unmanned Aerial Vehicle (UAV), a crucial component responsible for the propulsion system is the electric motor. Over the years, different types of electric motors, including Brushless Direct Current (BLDC), have supported the UAV’s propulsion system in diverse configurations. However, in the context of flux flow, the Radial Flux Permanent Magnet Motor (RFPMM) has been given more priority than the Axial Flux Permanent Magnet Motor (AFPMM) due to its sustainability in design and construction. Nevertheless, the AFPMM boasts higher speed, power density, lower weight, and greater efficiency than the RFPMM, because of its shorter flux path and the absence of end-turn winding. Therefore, this paper focuses on conducting a suitability analysis of an AFPMM as a shaft-connected propeller-mounted motor, with the intention of replacing the RFPMM in UAV applications.

This research employs a comprehensive methodology to explore hypersonic boundary layers' stability and transition dynamics, focusing specifically on the influence of sharp and blunt leading edges. The Stanford University Unstructured (SU2) Computational Fluid Dynamics (CFD) solver is utilized to compute the mean flow over a flat plate, establishing a foundational basis for subsequent stability analysis. The extracted boundary layer profiles undergo validation against existing literature, ensuring accuracy and reliability. Further analysis is conducted using a Python code to generate input files for the Linear Stability Solver. The Linear Stability Solver analysis constitutes a crucial phase wherein the research delves into the eigenvalue spectra, identifying dominant modes and closely scrutinizing the role of the modes in the transition process within the hypersonic boundary layers.

For spacecraft whose missions are considered low risk, it is typical for units to be subjected to unit-level thermal cycle and thermal vacuum testing. In recent years, however, the desire to reduce program costs and shorten development schedules has the aerospace testing community questioning the value of thermal vacuum testing all units. There may be instances where unit-level thermal vacuum testing is unnecessary if it can be shown that the unit’s design and performance is insensitive to the vacuum environment and that failures associated with the vacuum environment can be detected in other unit-level testing. The prescription of conditions under which unit thermal vacuum testing may be exempted should focus on establishing proven heritage, demonstrating design robustness through analysis and development testing, and reducing incurred risk. A general list of considerations by which vacuum-sensitivity may be assessed is provided herein.

Heavy duty valvetrains have evolved over the last 20 years with the integration of engine braking into the valvetrain. Jacobs Vehicle Systems have developed the High Power Density (HPD) engine brake that increases retarding powe, especially at low engine speed. The system works by converting the engine from a 4 stroke during positive power into a 2 stroke for retarding power. This more than doubles the retarding power at cruise engine speeds reducing the need to downshift in order to control the vehicle, compensates for reduction in natural vehicle retarding due to aerodynamic and friction enhancements, and enables the same vehicle retarding power with a smaller displacement engine as engine downsizing becomes prevalent. This paper describes lessons learnt during a recent vehicle demonstration project undertaken by Jacobs including performance, durability, integration with the engine powertrain, controls development, calibration, management of air system and transient operation.

The Daimler Detroit AssuranceⓇ 4.0 collision mitigation system is able to assist a driver in various aspects of safely operating their vehicle. One capability is the Active Brake Assist (ABA), which uses the Video Radar Decision Unit (VRDU) to communicate with the front bumper-mounted radar to provide information about potential hazards to the driver. The VRDU may warn the driver of potential hazards and apply partial or full braking, depending on the data being gathered and analyzed. The VRDU also records event data when an ABA event occurs. This data may be extracted from the VRDU using Detroit DiagnosticLink software. This paper presents an overview of the VRDU functionality and examines aspects of VRDU data such as the range and resolution of data elements, the synchronicity or timing of the recorded data, and application of the data for use in the analysis of crashes.

There have been many studies regarding the stability of vehicles following a sudden air loss event in a tire. Previous works have included literature reviews, full-scale vehicle testing, and computer modeling analyses. Some works have validated physics-based computer vehicle simulation models for passenger vehicles and other works have validated models for heavy commercial vehicles. This work describes a study wherein a validated vehicle dynamics computer model has been applied to extrapolate results to higher event speeds that are consistent with travel speeds on contemporary North American highways. This work applies previously validated vehicle dynamics models to study the stability of a five-axle commercial tractor-semitrailer vehicle following a sudden air loss event for a steer axle tire. Further, the work endeavors to understand the analytical tire model for tires that experience a sudden air loss.

The transition towards electrification in commercial vehicles has received more attention in recent years. This paper details the conversion of a production Medium-Duty class-5 commercial truck, originally equipped with a gasoline engine and 10-speed automatic transmission, into a battery electric vehicle (BEV). The conversion process involved the removal of the internal combustion engine, transmission, and differential unit, followed by the integration of an ePropulsion system, including a newly developed dual-motor beam axle that propels the rear wheels. Other systems added include an 800V/99 kWh battery pack, advanced silicon carbide (SiC) inverters, an upgraded thermal management system, and a DC fast charging system. A key part of the work was the development of the propulsion system controls, which prioritized drivability, NVH suppression, and energy optimization.

In order to resolve global atmospheric environmental issues, latest diesel engines for industrial machinery are required to reduce the emission of harmful gases such as carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx), and particulate matter (PM). For this reason, it is essential to mount exhaust gas after treatment devices such as diesel particulate filter (DPF) and diesel oxidation catalyst (DOC) on diesel engine. Engines mounted DPF must carry out DPF regeneration that burns and removes PM. Generator engine has characteristic of being operated for a long time under light load condition with low exhaust temperature which is difficult for DPF regeneration. In addition, generating white smoke and inlet face clogging of DOC are caused by accumulated soot containing HC at the DOC when operating engine continuously under light load condition.

This paper reports on seventy additional tests conducted using a mechanical device described by Bonugli et al. [4]. The method utilized quasi-static loading of bumper systems and other vehicle components to measure their force-deflection properties. Corridors on the force-deflection plots, for various vehicle combinations, were determined in order to define the system stiffness of the combined vehicle components. Loading path and peak force measurements can then be used to evaluate the impact severity for low speed collisions in terms of delta-v and acceleration. The additional tests refine the stiffness corridors, previously published, which cover a wide range of vehicle types and impact configurations. The compression phase of a low speed collision can be modeled as a spring that is defined by the force-deflection corridors. This is followed by a linear rebound phase based on published restitution values [1,5].

Lifting axles are auxiliary axles that provide increased load carrying capacity in heavy commercial vehicles. Lift axle gives better fuel efficiency as well as it reduces the operational costs by means of increasing the loading carrying capacity. These axles are raised when the vehicle is in unloaded condition, thus increasing the traction on remaining wheels and reducing the tire wear which in turn lower down the maintenance cost of the vehicle. Lifting height and force requires to lift the whole mechanism and are two main considerable factors to design the lifting axle mechanism. Although in India currently, the use of lift mechanism of single tire with continuous axle is more common. But in the case of pusher axle, continuous axle is unable to lift more after certain height because of the draft angle of the propeller shaft, and single tire axle which has less load carrying capacity up to 6T (Tons).

Battery electric vehicles are quickly gaining momentum to improve vehicle fuel efficiency and emission reduction. However, they must be designed to provide adequate range on a single charge combined with good acceleration performance, top speed, gradeability, and fast charging times. The paper presents a model for sizing the power train of an electric vehicle, including the power electronic converter, electric motor, and battery pack. A major assumption is that an optimal wheel slip rate can be achieved by modern vehicles using slip control systems. MATLAB/Simulink was used to model the vehicle powertrain. Simulations were conducted based on different speed and acceleration profiles. The purpose of the study focused on the motor and power electronics sizing requirements to achieve optimal range and performance.

This paper presents an optimal control co-design framework of a parallel electric-hydraulic hybrid powertrain specifically tailored for heavy-duty vehicles. A pure electric powertrain, comprising a rechargeable lithium-ion battery, a highly efficient electric motor, and a single or double-speed gearbox, has garnered significant attention in the automotive sector due to the increasing demand for clean and efficient mobility. However, the state-of-the-art has demonstrated limited capabilities and has struggled to meet the design requirements of heavy-duty vehicles with high power demands, such as a class 8 semi-trailer truck. This is especially evident in terms of a driving range on one battery charge, battery charging time, and load-carrying capacity. These challenges primarily stem from the low power density of lithium-ion batteries and the low energy conversion efficiency of electric motors at low speeds.

In recent decades, research based innovative system-on-chip (SoC) design has been a very important issue, due to the emerging trends and application challenges. The SoCs encompass digital, analog and mixed-signal hardware and software components and even sensors and actuators. Modelling and simulation constitute a powerful method for designing and evaluating complex systems and processes for many analysts and project managers as they engage in state of-the-art research and development. Modelling and simulations not only help them with the algorithm or concept realization and design feasibility, but it also allows experimentation, optimization, interpretation of results and validation of model.

Lunar tubes, natural underground structures on the Moon formed by ancient volcanic activity, offer natural protection from extreme temperatures, radiation, and micro-meteorite impacts, making them prime candidates for future lunar bases. However, the exploration of lunar tubes requires a high degree of mobility. Given the Moon's gravity, which is approximately six times weaker than Earth's, efficient navigation across rugged terrains within these lava tubes is achievable through jumping. In this work, we present the design of subsystems for a miniature hexapod rover weighing 1 kg, which can walk, jump, and stow. The walking system consists of two subsystems: one for in-plane walking, employing four single-degree-of-freedom (DOF) legs utilizing the KLANN walking mechanism, and another for directional adjustments before jumping. The latter employs a novel three-DOF mechanism employing a cable pulley mechanism to optimize space utilization.

The finite element method is one of the most robust tools in structural analysis. Typically, the input parameters in a finite element model are assumed to be deterministic. However, in practice, almost all material and geometrical properties, including the load, possess randomness. The consideration of the probabilistic nature of these quantities is essential to effectively designing a system that is robust against the uncertainties arising due to the variation in the input parameters, the significance of which has been documented by NASA in “Probabilistic Risk Assessment Procedures Guide for NASA Managers and Practitioners”, 2011. Among the various techniques applicable for stochastic analysis, the perturbation method, which is based on a sound mathematical foundation derived from Taylor’s series expansion, is widely acknowledged for its much higher efficiency compared to the well-known Monte-Carlo method.

In recent years, the burgeoning applications of hydrogen fuel cells have ignited a growing trend in their integration within the transportation sector, with a particular focus on their potential use in multi-rotor drones. The heightened mass-based energy density of fuel cells positions them as promising alternatives to current lithium battery-powered drones, especially as the demand for extended flight durations increases. This article undertakes a comprehensive exploration, comparing the performance of lithium batteries against air-cooled fuel cells, specifically within the context of multi-rotor drones with a 3.5kW power requirement. The study reveals that, for the specified power demand, air-cooled fuel cells outperform lithium batteries, establishing them as a more efficient solution.

The transportation sector still depends on conventional engines in many countries as the alternative technologies are not mature enough to reduce carbon footprints in society. The four-stroke diesel engines, primarily used for heavy-duty applications, need either high intake boosting or a large bore to produce higher torque and power output. There is an alternative where a four-stroke engine operated in two-stroke mode with the help of a fully flexible variable valve actuation (VVA) system can achieve similar power density without raising the intake boosting or engine size. A fully flexible VVA is required to control the valve events (lift, timing, and durations) independently so that the four-stroke events can be completed in one cycle. In this study, 1D-3D CFD coupled simulations were performed to develop a gas exchange process for better air entrapment in the cylinder and evacuate the exhaust products simultaneously.

Replacement of chromium containing materials and processes is the focus of extensive research and development activity due to increasingly stringent environmental regulations stemming from hexavalent chromium toxicity concerns. This, in turn, has increased the cost of hardware manufacture. This paper describes the efforts of Boeing Commercial Airplanes in developing a more environmentally suitable alternative process to chromic acid anodizing. Several alternative processes were evaluated prior to selection of a boric-sulfuric acid anodize (BSAA) process. Results of screening tests (including corrosion resistance, paint adhesion, abrasion resistance and fatigue life) and subsequent BSAA process optimization are included.