Search Results

The study emphasizes transitioning school buses from diesel to electric to mitigate their environmental impact, addressing challenges like limited driving range through predictive models. This research introduces a comprehensive control-oriented model for estimating auxiliary loads in electric school buses. It begins by developing a transient thermal model capturing cabin behavior, divided into passenger and driver zones. Integrated with a control-oriented HVAC model, it estimates heating and cooling loads for desired cabin temperatures under various conditions. Real-world operational data from school bus specifications enhance the model’s practicality. The models are calibrated using experimental cabin-HVAC data, resulting in a remarkable overall Root Mean Square Error (RMSE) of 2.35°C and 1.88°C between experimental and simulated cabin temperatures.

Global automobile manufacturers are increasingly adopting vehicle architecture development systems in the early stages of product development. This strategic move is aimed at rationalizing their product portfolios based on similar specifications and functions, with the overarching goal of simplifying design complexities and enabling the creation of scalable vehicles. Nevertheless, ensuring consistent performance in this dynamic context poses formidable challenges due to the wide range of design possibilities and potential variations at each development stage. This paper introduces an efficient reliability analysis process designed to identify and mitigate the distribution of Ride and Handling (R&H) performance. We employ a range of reliability analysis techniques, including Latin Hypercube Sampling and the enhanced Dimension Reduction (eDR) method, utilizing various types of models such as surrogate models and multi-body dynamics models.

The ball joint with cross groove offers both angular and plunging motion. When transmitting the same torque, the cross groove ball joint is lighter than other plunging Constant Velocity Joints (CVJs). It is crucial for the design of the joint and enhancing the contact fatigue life of the raceway to accurately estimate component loads of the ball joints with cross groove. In this study, the transmission efficiency of the joint and the peak value of contact force between ball and the track are used as evaluation indexes for characterizing dynamic performance of the joint. A multibody dynamic model of the joint is established to calculate its dynamic performance. In the model, the contact properties and friction characteristics of the internal structures were modeled, and a nonlinear equivalent spring and damping model was adopted for estimating the contact force. The transmission efficiency loss of the cross groove joint was measured and compared with the calculated values.

The problem of keeping the stable starting performance of diesel engine under high altitude and low temperature conditions has been done a lot of research in the field of diesel engine, but there is a lack of research on extreme conditions such as above 2000 meters above sea level and below 0°C. Aiming at solving the cold start problem of diesel engine in extreme environment, a set of chamber system of cold start environment diesel engine was constructed to simulate environment of 3000m altitude and -20°C. A series of experimental research was conducted on cold start efficiency optimization strategy of a certain type of diesel engine at 3000m altitude and -20°C. In parallel, a diesel engine model was constructed through Chemkin to explore the influence of the three parameters of compression ratio, stroke length, and fuel injection advance angle on the first cold start cycle of diesel engine at 4000m altitude and -20°C.

Currently, the rapid expansion of the global road transport industry and the imperative to reduce carbon emissions are propelling the advancement of electrified highways (EH). In order to conduct a comprehensive economic analysis of EH, it is crucial to develop a detailed /8.and comprehensive economic model that takes into account various transportation modes and factors that influence the economy. However, the existing economic models for EH lack comprehensiveness in terms of considering different transportation modes and economic factors. This study aims to fill this gap by designing an economic model for an EH-based Online DC-driven system (ODS) for long distance heavy-duty transport vehicle incorporating multi-factor sensitivities. Firstly, the performance parameters of the key components of the system are calculated using vehicle dynamics equations which involves selecting and matching the relevant components and determining the fundamental cost of vehicle transformation.

The influence of a split-injection strategy on energy-assisted compression-ignition (EACI) combustion of low-cetane number sustainable aviation fuels was investigated in a single-cylinder direct-injection compression-ignition engine using a ceramic ignition assistant (IA). Two low-cetane number fuels were studied: a low-cetane number alcohol-to-jet (ATJ) sustainable aviation fuel (SAF) with a derived cetane number (DCN) of 17.4 and a binary blend of ATJ with F24 (Jet-A fuel with military additives, DCN 45.8) with a blend DCN of 25.9 (25 vol.% F24, 75 vol.% ATJ). A pilot injection mass sweep (3.5-7.0 mg) with constant total injection mass and an injection dwell sweep (1.5-3.0 ms) with fixed main injection timing was performed. Increasing pilot injection mass was found to reduce cycle-to-cycle combustion phasing variability by promoting a shorter and more repeatable combustion event for the main injection with a shorter ignition delay.

The tire cornering stiffness plays a vital role in the functionality of vehicle dynamics control systems, particularly when it comes to stability and path tracking controllers. This parameter relies on various external variables such as the tire/ambient temperature, tire wear condition, the road surface state, etc. Ensuring a reliable estimation of the cornering stiffness value is crucial for control systems. This ensures that these systems can accurately compute actuator requests in a wide range of driving conditions. In this paper, a novel estimation method is introduced that relies solely on standard vehicle sensor data, including data such as steering wheel angles, longitudinal acceleration, lateral acceleration, yaw rate, and vehicle speed, among others. Initially, the vehicle's handling characteristics are deduced by estimating the understeer gradient.

Emission regulations are becoming more stringent, as global temperature continues to rise due to the increasing greenhouse gases in the atmosphere. Battery electric vehicles (BEV), which have zero tailpipe emissions, are expected to become widespread to solve this problem. As the powertrain of BEV is more efficient than conventional powered vehicles, the proportion of energy loss during driving due to aerodynamic drag becomes greater. Therefore, reducing aerodynamic drag for improved energy efficiency is important to extend the pure electric range. At Honda, Computational Fluid Dynamics (CFD) and wind tunnel testing are used to optimize vehicle shape and reduce aerodynamic drag. Highly accurate CFD is essential to efficiently guide the development process towards reducing aerodynamic drag. Specifically, the prediction accuracy for the exterior shape, underfloor devices, tires, and wheels must meet development requirements.

Additive manufacturing is currently being investigated for the production of components aiming for near net shape. The presence of chopped glass fibers with PA6 increases the melt viscosity and also changes the coefficients of thermal expansion and increase the heat resistance. The great dimensional stability obtained with the fusion of the PA6 with the fiber results in an extremely durable material even in adverse environments for many other materials used in 3D printing. PA6 is a material oriented for users who need to make structural parts and exposed to high mechanical stresses. The impact, test tensile, and flexural results for as-built PA6 with various infill patterns, including grid, triangle, trihexagon, and cubic, are tested.

The flight area of drones and other unmanned aerial vehicles (UAVs) had been highly restricted but has been relaxing, including flights beyond the scope of sight. Deregulation without aircraft-reliability improvement increases the risk of accidents. However, demanding high reliability for all aircraft leads to an increase in the price of the aircraft. Therefore, if airspace restrictions are relaxed for more reliable aircraft, the cost of higher reliability and its benefits can be balanced. This will improve efficiency and optimize cost-effectiveness. The purpose of this proposal is to balance the cost of aircraft-reliability improvement (which allows flight to continue in the event of a failure) and its advantages. Specifically, the author proposes rules that apply more relaxed airspace restrictions to UAVs with higher FCLs (Flight Continuity Possibility Levels) and stricter airspace restrictions to those with lower FCLs.

An escalating demand for improved heat dissipation from electronic components is driven by the imperative need to eliminate the accumulated heat that gradually builds up over time. In this study, a 3-D simulation was carried out to analyze the heat distribution performance of a heat sink based on PCM/NePCM. The heat sink was subjected to varying heat fluxes ranging from 3-7 kW/m2, and its performance was evaluated over time. The findings of the computational research indicate that using PCM assists in maintaining the heat sink base's temperature within lower bounds, and leads to uniform melting within the heat sink. Further, inclusion of Alumina nano particles integration in PCM enhanced the performance of heat sink. The percentage reduction in charging time of NePCM without fins (φ = 1%, 2.5% and 5%) in comparison to the Pure-PCM (φ = 0%) is 6%, 11% and 51% respectively at 6 kW/m2 input.

Although there have been significant advancements in vision-based localization techniques over recent years, there are still problems that need to be addressed. One of these problems is localization in dynamically illuminated environments, like one might find when a small unmanned aerial system (sUAS) equipped with a lighting payload attempts to autonomously navigate inside a dark, damaged structure. When visual odometry (VO) methods are implemented in a dynamically illuminated environment, the accuracy of the state estimation degrades because the shadows are improperly identified as features and these shadow-features move in a different manner than static objects in the environment. As a result, sUAS pose estimates often accumulate errors without bound. This work will examine the merits and demerits inherent in conventional or prevailing sUAS self-localization techniques in dark environments.

Optical motion capture (OMC) is a relatively new experimental tool used in many branches of science and engineering. Despite OMC’s widespread use, literature and practical procedures on the quantification of error and uncertainty in OMC systems for rigid bodies are currently underdeveloped. However, in most studies involving error and uncertainty quantification, the OMC volumes are relatively small (maximum length of 2m in any dimension) and involve expensive experimental apparatuses. Therefore, a cost-effective procedure to quantify the positional errors and uncertainties present in a large volume OMC system is presented. The procedure utilizes the kinematics of a wooden block traveling through air to predict errors and uncertainties in the OMC system by only collecting trajectory data.

Airworthiness Directives (ADs) serve as a medium through which commercial and military regulators improve the system’s performance by responding to the failure of the airplanes. The Federal Aviation Administration (FAA) and United States Air Force (USAF) provide ADs that detail overall cost on operators. The dataset derived from the Boeing 767 (B767) and its military derivatives, USAF’s KC-46A gives ideas into sensor solutions and maintenance approaches that may reduce these costs. Given the ADs significant costs for Boeing 767 operations, an analytical failure framework that determines the failure modes and failure mechanisms is introduced. For example, a huge portion of severe impairment (e.g., cracking, corrosion, and chafing) constitutes 27% of failure mechanisms in these systems. To reduce future B767 ADs for commercial and military operators, sensor solution and maintenance strategies using performance metric and genetic algorithm are assessed.

The number of Unmanned Aircraft Systems (UAS) has been growing over the past few years and will continue to grow at a faster pace in the near future. UAS faces many challenges in certification, airspace management, operations, supply chain, and maintenance. Blockchain, defined as a distributed ledger technology for the enterprise that features immutability, traceability, automation, data privacy, and security, can help address some of these challenges. However, blockchain also has certain drawbacks and, additionally, it is still not fully mature. Hence it is essential to study how blockchain can help UAS. This Aerospace Information Report (AIR) presents the current opportunities, challenges of UAS operating at or below 400 ft Above Ground Level (AGL) altitude for commercial use and how blockchain can help meet these challenges. It also provides requirements for developing a blockchain solution for UAS along with the need for the standardization of blockchain enabled processes.

The aerospace industry is noticing significant shift towards More Electric Aircraft (MEA). The advancement of electrical technology the systems are being transformed towards electric compared to the conventional pneumatic or hydraulic systems. This has led to an increased demand in electrical power from 150 Kilo Watts in the conventional airplane to 1 Mega Watts in More Electric Aircraft. More electric systems, call for increased electrical wiring harness to connect various systems in the aircraft. These harnesses consist of power and data cables. Wireless communication technology is being matured for data communication, leading to reduction of wire harness for data. As of now, the length of wires in large commercial aircraft is over 100miles and it may not be surprising if the electrification of aircraft drive this too much longer.

The safety of commercial aviation industry has come under extensive scrutiny and how the system safety process is applied. One specific system safety regulation concerns how unsafe system operating conditions are meeting regulatory requirements. Minimal regulatory guidance was available on this topic and an industry committee (American Society for Testing of Materials) decided to provide a consensus standard with input from a cross-section of airplane manufacturers, suppliers, and regulatory authorities on what is meant by an unsafe system operating condition and how compliance can be shown to the regulation(s). The committee determined that an unsafe system operating condition is when a failure condition severity increases (to hazardous or catastrophic) due to crewmember(s) inaction. For example, if a hazard has occurred it is possible the severity can increase to an unacceptable level as the crewmember(s) are not aware of the hazard.

Previously given Paper 09ATC-0232 delivered at the SAE Aerotech conference in Seattle in 2009 reports on the E6000 machine installing slug rivets with the EMR. Paper 2015-01-2491given at the SAE conference in Seattle in 2015 reports on index head rivets being installed with screw driven squeeze process. This paper reports on the screw driven squeeze process installing unheaded slug rivet which is a more complex process. We also report on improvements to the fixture automation.

Large diameter, tightly toleranced fastener patterns are commonplace in aerospace structures. Satisfactory generation of these holes is often challenging and can be further complicated by difficult or obstructed access. Bespoke tooling and drill jigs are typically used in conjunction with power feed units leading to a manual, inflexible, and expensive manufacturing process. For 777X flap production, Boeing and Electroimpact collaborated to create a novel, automated solution to generate the fastener holes for the main carrier fitting attachment pattern. Existing robotic automation used for skin to substructure assembly was modified to utilize extended length (up to 635mm), bearing-supported drill bar sub-assemblies. These Long Assembly Drills (LADs) had to be easily attached and detached by one operator, interface with the existing spindle(s), supply cutting lubricant, extract swarf on demand, and include a means for automatically locating datum features.

Large-scale aerostructures are commonly constructed using multiple layers of stacked material which are fastened together using mechanical methods. Ensuring the interface gaps between these materials are kept within engineering tolerances is of utmost importance to the structural integrity of the aircraft over its service life. Manual, right angle feeler gauges are the traditional method for measurement of interface gaps, but this method is tedious and mechanic dependent. A portable hand tool utilizing low-coherence interferometry has been developed to address these issues. The tool uses a right-angle probe tip which is inserted into a previously drilled hole and driven through the depth of the material. A line scan of data is collected and analyzed for the presence of interface gaps. To measure the consistency of the gap around the circumference of the hole, the tool is rotated by the operator and additional scans are collected.