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Two parallel HEV control concepts: ‘thermostat’ and ‘power split’ are compared in this paper. To achieve a substantial improvement in fuel economy, the ‘thermostat’ or ‘on/off’ control technique intended to improve the fuel efficiency of a series HEV has been adopted and designed for parallel HEV. Among different ‘power split’ concepts developed for parallel hybrids only the ‘electrically assist’ algorithm is considered in this paper. These two control concepts are compared for three parallel HEV architectures: pre-transmission, post-transmission and continuous variable transmission hybrids. The comparison study also includes the effect of hybridization factor-the ratio of the electric power to the total propulsion power. The matrices of comparison are level of performance, energy consumption and exhaust emissions. The SAE J1711 partial charge test procedure is followed.

Future electronics and photonics systems, weapons systems, and environmental control systems in aircraft will require advanced thermal management technology to control the temperature of critical components. Two-phase Thermal Management Systems (TMS) are attractive because they are compact, lightweight, and efficient. However, maintaining stable and reliable cooling in a two-phase flow system presents unique design challenges, particularly for systems with parallel evaporators during thermal transients. Furthermore, preventing ingress of liquid into a vapor compressor during variable-gravity operation is critical for long-term reliability and life. To enable stable and reliable cooling, a highly stable two-phase system is being developed that can effectively suppress flow instability in a system with parallel evaporators. Flow stability is achieved by ensuring that only single-phase liquid enters the evaporators.

OBD (On Board Diagnosis) has been applied to detect malfunctions in powertrains. OBD requirements have been extended to detect various failures for ensuring the vehicle emission control system being normal. That causes further costs for additional sensors and software works. Two layers diagnosis system is proposed for a passenger car gearbox system to detect changes from normal behavior. Conventional physical constraints based diagnosis is placed on the base layer. Model based diagnosis and specific symptom finding diagnosis are built on the second layer. Conventional physical constraints based diagnosis is direct and effective way to detect the failure of system if the detected signals exceed their normal ranges. However under the case of system failure with related signals still remain in normal ranges, the conventional detection measures can not work normally. Under this case, Model based diagnosis is proposed to enhance the functionality of diagnosis system.

Force and moment measurements, and surface flow patterns have been obtained for a one-fifth scale model of a single-engine general aviation aircraft utilizing a 15% thick natural laminar flow wing section. The data is for typical pre- and post-stall angles of attack, aircraft yaw attitudes, surface roughness and Reynolds number conditions. Results from a separate study of the wing alone are also given for comparison. This comparison shows that the fuselage/tail assembly acts as a lifting body. The aerodynamic characteristics show marked deterioration with increasing surface roughness. In addition, the studies indicate that the transition on the wing is characterized by laminar short bubble separation. The aerodynamic characteristics are somewhat unaffected by the presence of mini-tufts. The flow visualization photographs clearly show the transition and separation regions, and document the effects of variations in angle of attack and yaw on wing body interference.

The last quarter century has seen CO2 emissions increase at a steadily increasing rate. In the U.S.A. alone from 1970 to 1992 the CO2 emissions have increased from 5.5 billion metric tons of carbon dioxide to 6.6 bmt. The transportation industry contributes currently (1991 figures) 24.7% of the total emissions from the United States. Transportation utilization has grown faster, however, but more efficient vehicles allow for more travel without increasing the CO2 proportionally. The advancements made in the 1980s have reduced emissions by 21 million tons of CO2 per year on average. Electric Vehicles have been a proposed method of reducing the CO2 emissions due to transportation. Electric vehicles produce no emissions while driving, making them ideal candidates for heavily polluted and concentrated areas such as urban locations. However, it is debatable if electric vehicles are feasible on the global scale of CO2 reduction.

The increasing number of gasoline direct injection (GDI) vehicles on the roads has drawn attention to their particulate matter (PM) emissions, which are greater both in number and mass than port fuel injected (PFI) spark ignition (SI) engines [1]. Regulations have been proposed and implemented to reduce exposure to PM, which has been shown to have negative impacts on both human health and the environment [2, 3]. Currently, the gasoline particulate filter (GPF) is the proposed method of reducing the amount of PM from vehicle exhaust, but modifications to improve the filtration efficiency (FE) and reduce the pressure drop across the filter are yet needed for implementation of this solution in on-road vehicles. This work evaluates the impacts of wall thickness and cell density on filtration efficiency and backpressure using a benchtop filtration system.

Finding a replacement for fossil fuels is critical for the future of automotive transportation. The compression ignition (CI) engine is an important aspect of everyday life by means of transportation and shipping of materials. Biodiesel is a viable augmentation for conventional diesel fuel in compression ignition engines. Biodiesel-fuelled diesel engines produce less particulate matter (PM) relative to conventional diesel and biodiesel has the ability to be a carbon dioxide (CO₂) neutral fuel, which may come under government regulation as a greenhouse gas. Although biodiesel is a viable diesel replacement and has certain emissions benefits, it typically also has a known characteristic of higher oxides of nitrogen (NOx) emissions relative to petroleum diesel. Advanced modes of combustion such as low temperature combustion (LTC) have attained much attention due to ever-increasing emission standards, and could also help reduce NOx in biodiesel.

In the wake of global focus shifting towards the health and conservation of the planet, greater importance is placed upon the hazardous emissions of our fossil fuels, as well as their finite supply. These two areas remain intense topics of research in order to reduce greenhouse gas emissions and increase the fuel efficiency of vehicles, a sector which is a major contributor to society's global CO₂ emissions and consumer of fossil-fuel resources. A particular solution to this problem is the diesel engine, with its inherently fuel-lean combustion, which gives rise to low CO₂ production and higher efficiencies than other potential powertrain solutions. Diesel engines, however, typically exhibit higher nitrogen oxides (NOx) and soot engine-out emissions than their gasoline counterparts. NOx is an ingredient to ground-level ozone production and smoke is a possible carcinogen, both of which are facing stricter emissions regulations.

Tradeoff studies are a common part of engineering practice. Designers conduct tradeoff studies in order to improve their understanding of how various design considerations relate to one another and to make decisions. Generally a tradeoff study involves a systematic multi-criteria evaluation of various alternatives for a particular system or subsystem. After evaluating these alternatives, designers eliminate those that perform poorly under the given criteria and explore more carefully those that remain. One limitation of current practice is that designers cannot combine the results of preexisting tradeoff studies under uncertainty. For deterministic problems, designers can use the Pareto dominance criterion to eliminate inferior designs. Prior work also exists on composing tradeoff studies performed under certainty using an extension of this criterion, called parameterized Pareto dominance.

This paper addresses the fundamental issues faced in the aircraft electrical system architectures. Furthermore, a brief description of the conventional and advanced aircraft power system architectures, their disadvantages, opportunities for improvement, future electric loads, role of power electronics, and present trends in aircraft power system research will be given. Finally, this paper concludes with a brief outline of the projected advancements in the future.

Conventional spark plugs ignite a fuel-air mixture via an electric-to-plasma energy transfer; the effectiveness of which can be described by an electric-to-plasma energy efficiency. Although conventional spark plug electric-to-plasma efficiencies have historically been viewed as adequate, it might be wondered how an increase in such an efficiency might translate (if at all) to improvements in the flame initiation period and eventual engine performance of a spark-ignition engine. A modification can be made to the spark plug that places a peaking capacitor in the path of the electrical current; upon coil energizing, the stored energy in the peaking capacitor substantially increases the energy delivered by the spark. A previous study has observed an improvement in the electric-to-plasma energy efficiency to around 50%, whereas the same study observed conventional spark plug electric-to-plasma energy efficiency to remain around 1%.

As emission standards become more stringent, many studies have been carried out to understand and reduce the emissions from diesel combustion engines, among which nitric oxide (NO) emissions and soot are known to have the trade-off relation during combustion processes. One aspect of this trade-off is manifested by the role radiation heat transfer plays on post-flame gas temperature, thus affecting NO formation. For example, a decrease in in-cylinder soot decreases radiation heat transfer causing an increase in post-flame gas temperature and partially contributing to the corresponding soot-NO relationship with an increase in NO formation. This topic has re-emerged with the increased use of biodiesel; a potential explanation for the so-called "biodiesel NOx penalty" is biodiesel's inherently reduced in-cylinder soot.

Gasoline Direct Injection (GDI) is known to produce lower concentrations of smaller particulate matter (PM) compared to diesel combustion [1]. The lower concentration results in the absence of soot-cake formation on the filter channel wall and therefore filtration behavior deviates from the expected diesel particulate filter (DPF) performance. Therefore, studies of cake-less filtration regimes for smaller sized particulates is of interest for GDI PM mitigation. This work investigates the filtration efficiency of laboratory-generated particulates, representative of GDI-sized PM, in uncoated, commercial DPF cordierite substrates of varying porosities. Size-dependent particulate concentrations were measured using a Scanning Mobility Particle Sizer (SMPS), both upstream and downstream of the filters. By comparing these measured concentrations, the particle size-dependent filtration efficiency of filter samples was calculated.

The purpose of this paper is to present an assessment of the negative impedance instability concept of the constant power loads in the More Electric Aircraft (MEA) power systems. We address the fundamental problems faced in the stability studies of these multi-converter power electronic systems. An approach to the design of sliding-mode controllers for PWM DC/DC converters with constant power loads is presented. Because of the negative impedance destabilizing characteristics of constant power loads, conventional linear control methods have stability limitations around the operating points. However, the proposed controllers improve large-signal stability and dynamic responses. The proposed controllers are simulated and their responses under different operations are discussed. Finally, we verify the stability of the controllers using the second theorem of Lyapunov.

Biodiesel remains an alternative fuel of interest for use in diesel engines. A common characteristic of biodiesel, relative to petroleum diesel, is a lowered heating value (or energy content of the fuel). A lower heating value of the fuel would, presuming all other parameters are equal, result in decreased engine torque. Since engine torque is often user-demanded, the lower heating value of the fuel generally translates into increased brake specific fuel consumption. Several literature report this characteristic of biodiesel. In spite of the wealth of fuel consumption characteristic data available for biodiesel, it is not clear how other engine performance parameters may change with the use of biodiesel. Characterizing these parameters becomes complicated when considering the interactions of the various engine systems, such as a variable geometry turbocharger with exhaust gas recirculation.

This paper presents calculations of engine flows by using the Partially-Averaged Navier Stokes (PANS) method (Girimaji [1]; [2]). The PANS is a scale-resolving turbulence computational approach designed to resolve large scale fluctuations and model the remainder with appropriate closures. Depending upon the prescribed cut-off length (filter width) the method adjusts seamlessly from the Reynolds-Averaged Navier-Stokes (RANS) to the Direct Numerical Solution (DNS) of the Navier-Stokes equations. The PANS method was successfully used for many applications but mainly on static geometries, e.g. Basara et al. [3]; [4]. This is due to the calculation of the cut-off control parameter which requires that the resolved kinetic energy is known and this is usually obtained by suitably averaging of the resolved field. Such averaging process is expensive and impractical for engines as it would require averaging per cycles.

Low temperature combustion (LTC) modes for reciprocating engines have been demonstrated with relatively high thermal efficiencies. These new combustion modes involve various combinations of stratification, lean mixtures, high levels of exhaust gas recirculation (EGR), multiple injections, variable valve timings, two fuels, and other such features. LTC engines may be attractive in combination with low heat rejection (LHR) engine concepts. The current work is aimed at evaluating the thermodynamic advantages of such a LTC-LHR engine. A thermodynamic cycle simulation was used to evaluate the effect of cylinder wall temperature on the engine performance, emissions and second law characteristics. An automotive engine at 2000 rpm with a bmep of 900 kPa was considered. Both a conventional and a LTC design were compared. The LTC engine realized small gains in efficiency whereas the conventional engine did not realize any significant gains as the cylinder wall temperature was increased.

This paper discusses different computer vision techniques investigated by the authors for identifying Emergency Vehicles (EV). Two independent EV identification frameworks were investigated: (1) A one-stage framework where an object detection algorithm is trained on a custom dataset to detect EVs, (2) A two-stage framework where an object classification algorithm is implemented in series with an object detection pipeline to classify vehicles into EVs and non-EVs. A comparative study is conducted for different multi-spectral feature vectors of the image, against several classification models implemented in framework 2. Additionally, a user-defined feature vector is defined and its performance is compared against the other feature vectors. Classification outputs from each of the frameworks are compared to the ground truth, and results are quantitatively listed to conclude upon the ideal decision rule.