Exclusive Operation Strategy for the Supervisory Control of Series Hybrid Electric Vehicles

Supervisory control systems (SCSs) are used to manage the powertrain of hybrid electric vehicles (HEV). This paper presents a novel SCS called Exclusive operation strategy (XOS) that applies simple rules based on the idea that batteries are efficient at lower loads while engines and generators are efficient at higher loads. The XOS is developed based on insights gained from three conventional SCSs for series HEVs: Thermostat control strategy (TCS), Power follower control strategy (PFCS) and Global equivalent consumption minimization strategy (GECMS). Also, recent technological developments have been considered to make the XOS more suited to modern HEVs than conventional SCSs. The resulting control decisions are shown to emulate the operation of approximate global optimal solutions and thus achieve significant improvement in fuel economy as compared to TCS and PFCS. In addition, the generally linear relationship between required power and engine power for the XOS provides auditory cues to the driver that are comparable to conventional vehicles, thus reducing barriers to adopting HEVs. The simplicity and effectiveness of the XOS makes it a practical SCS

Dynamic modeling platform for series hybrid electric vehicles

This paper introduces a simulation model that can be used to develop and test designs and control systems for hybrid electric vehicles (HEVs). The work involves a novel simulating platform, developed in Simulink, where each component of a series HEV is developed using a first-principles approach in a modular fashion, validated by available experimental data and then integrated to form a coupled nonlinear dynamic model. The vehicle model is capable to act as a platform for the design of supervisory control systems (SCSs) that optimize the energy flow in the powertrain. Simulations with two distinct SCSs and two driving cycles are used to analyze the vehicle performance under varying driving and operating conditions. The results demonstrate the applicability of the model for realistic prediction of both vehicle behavior and component energy losses, design optimization and control system design

Mode properties of annular gain lasers

The properties of a new class of laser resonators are investigated theoretically and experimentally. In these lasers the radiation propagates longitudinally in an annular amplifying medium, and useful low loss modes can be obtained even when the axial region is obscured. Alignment characteristics and far field patterns are discussed, and experiments have been conducted using coaxial double-discharge CO₂ devices

Air Breakdown in a Radial-Mode Focusing Element

A new radial focusing device is described that condenses an incident laser beam to an extremely intense and uniformly illuminated focal spot. The focal region is useful for many applications. When used with a 10.6-µm CO₂ TEA laser source, a disk-shaped air-breakdown spark results, and the properties of this spark have been investigated

Discrimination and visualization of ELM types based on a probabilistic description of inter-ELM waiting times

Discrimination and visualization of different observed classes of edge-localized plasma instabilities (ELMs), using advanced data analysis techniques has been considered. An automated ELM type classifier which effectively incorporates measurement uncertainties is developed herein and applied to the discrimination of type I and type III ELMs in a set of carbon-wall JET plasmas. The approach involves constructing probability density functions (PDFs) for inter-ELM waiting times and global plasma parameters and then utilizing an effective similarity measure for comparing distributions: the Rao geodesic distance (GD). It is demonstrated that complete probability distributions of plasma parameters contain significantly more information than the measurement values alone, enabling effective discrimination of ELM type

The additive effect of a stem galling moth and a competitive plant on parthenium weed under CO2 enrichment

Parthenium weed (Parthenium hysterophorus) is a highly invasive plant that has invaded many parts of world including Australia. The present study reports on the effects of rising [CO2] on the performance of one of its biological control agents, stem-galling moth (Epiblema strenuana) when combined with a competitive plant, buffel grass (Cenchrus cilliaris). The study was carried out under controlled environment facilities during 2010–11. P. hysterophorus when grown under elevated [CO2] of 550 µmol mol−1, produced a greater biomass (27%), attained greater stature (31%), produced more branches (45%) and seeds plant−1 (20%), than those grown at ambient [CO2] of 380 µmol mol−1. Buffel grass reduced the biomass and seed production of P. hysterophorus plants by 33% and 22% under ambient [CO2] and by 19% and 17% under elevated [CO2], respectively. The combined effect of buffel grass and E. strenuana reduced dry biomass and seed production by 42% and 72% under ambient [CO2] and 29% and 37% elevated [CO2], respectively. Although the suppressive effect was different between ambient and elevated [CO2], the effect is likely to be retained. Stem gall formation by E. strenuana significantly enhanced the lateral branch production in plants grown under both [CO2]. Epiblema strenuana did not reduce the seed production of P. hysterophorus under the elevated [CO2] nevertheless, our earlier study had confirmed that many of the seeds produced under such conditions are not filled. This study has highlighted that the additive suppressive effect of E. strenuana and buffel grass on P. hysterophorus growth would be retained under future atmospheric CO2 enrichment

The additive effect of a stem galling moth and a competitive plant on parthenium weed under CO2 enrichment

Parthenium weed (Parthenium hysterophorus) is a highly invasive plant that has invaded many parts of world including Australia. The present study reports on the effects of rising [CO2] on the performance of one of its biological control agents, stem-galling moth (Epiblema strenuana) when combined with a competitive plant, buffel grass (Cenchrus cilliaris). The study was carried out under controlled environment facilities during 2010–11. P. hysterophorus when grown under elevated [CO2] of 550 µmol mol−1, produced a greater biomass (27%), attained greater stature (31%), produced more branches (45%) and seeds plant−1 (20%), than those grown at ambient [CO2] of 380 µmol mol−1. Buffel grass reduced the biomass and seed production of P. hysterophorus plants by 33% and 22% under ambient [CO2] and by 19% and 17% under elevated [CO2], respectively. The combined effect of buffel grass and E. strenuana reduced dry biomass and seed production by 42% and 72% under ambient [CO2] and 29% and 37% elevated [CO2], respectively. Although the suppressive effect was different between ambient and elevated [CO2], the effect is likely to be retained. Stem gall formation by E. strenuana significantly enhanced the lateral branch production in plants grown under both [CO2]. Epiblema strenuana did not reduce the seed production of P. hysterophorus under the elevated [CO2] nevertheless, our earlier study had confirmed that many of the seeds produced under such conditions are not filled. This study has highlighted that the additive suppressive effect of E. strenuana and buffel grass on P. hysterophorus growth would be retained under future atmospheric CO2 enrichment

Workshop on Engineering Turbulence Modeling

Discussed here is the future direction of various levels of engineering turbulence modeling related to computational fluid dynamics (CFD) computations for propulsion. For each level of computation, there are a few turbulence models which represent the state-of-the-art for that level. However, it is important to know their capabilities as well as their deficiencies in order to help engineers select and implement the appropriate models in their real world engineering calculations. This will also help turbulence modelers perceive the future directions for improving turbulence models. The focus is on one-point closure models (i.e., from algebraic models to higher order moment closure schemes and partial differential equation methods) which can be applied to CFD computations. However, other schemes helpful in developing one-point closure models, are also discussed

Real-time control strategy to maximize hybrid electric vehicle powertrain efficiency

The proposed supervisory control system (SCS) uses a control map to maximize the powertrain efficiency of a hybrid electric vehicle (HEV) in real-time. The paper presents the methodology and structure of the control, including a novel, comprehensive and unified expression for the overall powertrain efficiency that considers the engine-generator set and the battery in depth as well as the power electronics. A control map is then produced with instructions for the optimal power share between the engine branch and battery branch of the vehicle such that the powertrain efficiency is maximized. This map is computed off-line and can thereafter be operated in real-time at very low computational cost. A charge sustaining factor is also developed and introduced to ensure the SCS operates the vehicle within desired SOC bounds. This SCS is then tested and benchmarked against two conventional control strategies in a high-fidelity vehicle model, representing a series HEV. Extensive simulation results are presented for repeated cycles of a diverse range of standard driving cycles, showing significant improvements in fuel economy (up to 20%) and less aggressive use of the battery