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A nominal 520 kW (thermal) air-conditioning system based on the seasonal storage of cold water in an aquifer has cooled a University of Alabama building since 1983. During cold weather, ambient, 18° C water is pumped from warm supply wells, chilled to about 6° C in a cooling tower, and reinjected into separate cold storage wells. In warm weather, water is withdrawn from the cold wells and pumped through building heat exchangers for air conditioning. Presented here are results of 6 years of study [sponsored by the U.S. Department of Energy through Pacific Northwest Laboratory] of the first successful U.S. application of this technology. This system yields high energy efficiency, with measured annual average COP of about 5 (SEER = 17 Btu/Wh), and energy recovery efficiency ranging from 40 to 85%, shifts utility loads from summer to winter, and no chlorofluorocarbon (CFC) release.

After about a decade of considerable investments in polymer electrolyte fuel cell (PEMFC) and in solid oxide fuel cell (SOFC) technology, both are being actively considered for vehicle applications. The two vehicle applications being most actively considered for fuel cells are propulsion (mainly for PEMFC) and auxiliary power (for both PEMFC and SOFC). For all transportation applications, fuel cells promise the benefits of clean and quiet operation, potentially low maintenance and high efficiency, and ultimately greater utility to drivers and passengers. Initial system and vehicle prototypes have started to demonstrate some of these benefits, but much technology development is still needed before commercialization can occur. Not surprisingly then, there are serious hurdles to be overcome if fuel cells are to become true competitors for internal combustion engines (ICEs) in automotive applications.

Storage stability of different diesel fuels containing cat-cracked stocks was examined using various aging conditions. The degradation of fuel during storage was monitored through insoluble formation but also through reaction of nitrogen compounds known to be involved in the fuel degradation process. The influence of aging in injector fouling tendency was also investigated on an IDI engine on test bench. Various stabilizer additives (tertiary amines, dispersant…) were tested. Best results were obtained with dispersants which prevent sediment agglomeration making them able to cross the filter mesh. Additives limit indole evolution without inhibiting completely sediment formation, proving that other reactions take place. We showed that fuel oxidability is not modified by additives. None of the tested formulations is effective on fuel darkening. After aging, surfactants remain effective on injector fouling. Another way of improving the storage stability of Diesel fuel is hydrotreatment.

Longer warranties, improved performance and higher operating efficiency demanded by end-users are placing more rigorous service requirements on all engine components. Seals are particularly vulnerable due to their organic nature. This paper reviews a series of fluoroelastomers to determine their long-term serviceability when in contact with conventional high-temperature engine lubricants and coolants. A typical application might be seals used for engine cylinder sleeves.

The objective of this study was to assess the long-term capability and impact of a rapid, in-situ impedance measurement technique known as Harmonic Compensated Synchronous Detection. This technique consists of a sum-of-sines excitation signal that includes a targeted selection of frequencies and only requires one period of the lowest frequency. For a given frequency range of 0.1 Hz to approximately 2 kHz, the measurement duration would only be ten seconds. The battery response is captured and synchronously detected for impedance spectra measurements. This technique was compared to laboratory-based performance degradation measurements using commercially available lithium-ion cells. The cells were aged for 150,000 cycles at accelerated rates using temperatures of 40 and 50°C. Every 30,000 cycles, cycle-life testing was interrupted to gauge degradation at the reference temperature of 30°C.

Four GL-5 gear lubricants, one containing a dispersed solid borate additive, two sulfur-phosphorus (S-P), and a S-P synthetic, were evaluated in the axles and transmissions of 26 new Class 8 trucks in a 250,000-mile field test. Significantly lower axle break-in wear (factory to first oil change) was found for the borate lubricant versus a S-P factory-fill oil. The four test oils showed statistically significant differences in axle wear as shown by iron wear plots and analysis of end-of-test parts: the borate and synthetic oils were equal while the other two oils gave higher wear. All oils gave acceptable seal performance. The borate lubricant showed the best thermal stability as judged by parts cleanliness.

An effective development strategy is needed to implement short development times for mechatronic systems, which themselves are becoming increasingly more complex. Besides the ever-increasing use of advanced computer-based development tools, special attention must be paid to the validation of the functional behavior of the prototype during all phases of the development process. Using the example of systems for powertrain automation, this paper depicts the resulting advantages arising from the long-time observation of time-based values of open- and closed-loop controlled systems. The method of long-time observation introduced here is based on the acquisition and analysis of information in all phases of the development process. Where numerous vehicles are already in the hands of selected customers during fleet tests, these late phases in particular are covered thoroughly. It should be noted that newly developed systems are normally unobserved or only subjectively evaluated by the driver.

Different realizations of adaptive cruise control systems (ACC) have been tested. Firstly, only throttle access has been realized. In addition to this, the second realization utilizes access to the automatic transmission ECU. Finally, the third realization includes access to the brakes. Essentially, the first two versions are characterized by different states (e.g. acceleration, hold speed, deceleration), while the third version is based on continuous longitudinal vehicle control, e.g. using fuzzy methods [1]. Practical results showed high system stability for all three ACC versions. Advantages and disadvantages of each realization have been worked out based on simulated and measured results. Measurements showed that the first two solutions are sufficient to handle many traffic situations. However, in comparison with these versions, the third realization turned out to be the most powerful one.

Cutting out of the lane in the process of following a car is a natural driving scene that often happens, and it is also a typical scene faced by self-driving cars. In this scenario, the driver may either change lanes after the car in front or continue in the original lane. Based on the natural driving data, the longitudinal driver response behavior of the scene cut out of the car in front is analyzed. For the driver's longitudinal response behavior, firstly, the acceleration behavior domain related to TV1 (Target Vehicle I) was divided by support vector machine method, and then the acceleration time was represented by the transverse body overlap rate of the Vehicle and the Vehicle in front at the initial acceleration time, and the acceleration response process was represented by the average acceleration and the maximum acceleration. The influencing factors were analyzed by single factor analysis of variance and Pearson correlation test.

The purpose of this paper is to present specifications for rubber tired vehicles operating on a cooperative highway. These specifications will allow control systems to be designed which could meet the requirement of a new generation of automobiles and trucks operating on roadways which can carry more vehicles/hr. These vehicles are to be electronically guided and controlled. The problem is divided into two aspects: 1. lateral control and 2. longitudinal control. Lateral control will be done by a sensor system that can “see” the road ahead and steer the vehicle toward the road and will be presented in another paper. Longitudinal control will be the subject of this paper. It involves keeping a series of dissimilar vehicles properly spaced while operating at high speeds. Safe spacing must be kept as vehicles enter and exit the vehicle stream, and as disturbances occur such as hills and winds.

Earlier research1 suggests there may be positive offset in the longitudinal G sensor in Toyota Corolla Gen 02 EDR’s. This research tests if a similar offset is present in Toyota Gen 04 EDR’s in the 2007 Yaris. A series of low speed forward and rearward collisions into a stationary vehicle were conducted. In addition to the installed vehicle ACM, additional identical “ride along” ACM’s were installed back to back, one front facing and one rear facing. The vehicle was also instrumented with a video VBOX to record speed at impact, and with the high precision “IST” accelerometer reference instrumentation. ACM’s facing toward the crash under-reported the negative longitudinal Delta V. After the initial impact was over, these forward facing ACM’s had a positive slope and at the end of the 200 ms recording were reporting a positive net Delta V, indicating a G sensor bias. The ACM’s facing away from the crash over reported the positive longitudinal Delta V.

Although it is intuitively and qualitatively known that a treaded tire has a larger drawbar pull than a smooth tire, little is known quantitatively about all the interfacial forces and the origins of these forces of a treaded tire traversing a snow cover. There have been relatively few studies regarding the quantitative effects of tread pattern on tire-snow interaction due to the complexity of the tread pattern, the enormous amount of computational resources needed for high-fidelity numerical simulations, and the difficulty of measuring all the interfacial forces between a tire that is much harder than snow. The purpose of this paper is to understand the effects of a simplified tread pattern of a two-dimensional rigid tire on the interfacial forces between a tire and low-density snow. The parameters to vary included the wheel load, as well as a full-range of longitudinal slip.

Driven by the necessity to reduce costs and improve products quality the automotive industry replaced the design method known as "trial and error" by those grounded on mathematical and physical theory. In this context, a longitudinal performance test was made by BAJA SAE UFMG team, in order to acquire vehicular performance data that will be used to validate computer models. The methodology consists of sensors and data acquisition system research, validation, fixation and installation in the vehicle, test and process of acquired data. From these steps, correlated data were acquired from magnitudes such as angular velocity in transmission shafts, global longitudinal acceleration and velocity, travel of break and throttle pedals and pressure inside of master cylinder. These results developed the knowledge about vehicular dynamic allowing the improvement of futures prototypes.

An integrated automatic driving system consists of perception, planning and control. As one of the key components of an autonomous driving system, the longitudinal planning module guides the vehicle to accelerate or decelerate automatically on the roads. A complete longitudinal planning module is supposed to consider the flexibility to various scenarios and multi-objective optimization including safety, comfort and efficiency. However, most of the current longitudinal planning methods can not meet all the requirements above. In order to satisfy the demands mentioned above, a new Potential Field (PF) based longitudinal planning method is presented in this paper. Firstly, a PF model is constructed to depict the potential risk of surrounding traffic entities, including obstacles and roads. The shape of each potential field is closely related to the property of the corresponding traffic entity.

The use of electric motors to independently control the torque of two or four wheels of a vehicle has the potential to significantly improve safety and handling. One virtue of electric motors is that their output torque can be accurately estimated. Using this known output torque, longitudinal tire force and coefficient of friction can be estimated via a controller output observer. This observer works by constructing a model of wheel dynamics, with longitudinal tire force as an unknown input quantity. A known wheel torque is input to the physical and modeled system and the resulting measured and predicted wheel speeds are compared. The error between the measured and predicted wheel speed is driven towards zero by a robust feedback controller. This controller modulates an estimate of longitudinal tire force used as an input by the wheel dynamics model. The resulting estimate of longitudinal tire force quickly converges towards the actual value with minimal computational expense.

Multi-body simulations are very powerful tools in the modeling of dynamic mechanical systems. This study uses the multi-body simulation program ADAMS to analyze a light vehicle suspension. The paper introduces ADAMS modeling concepts and then applies them in a case study examining the effects of additional longitudinal compliance on the ride and handling behavior of a 1/4 car suspension model. The results were a marginal increase in the lateral stiffness of the vehicle, approximately the same ride performance, and an increase in the compliance steering angle.

System identification is an important aspect in model-based control design which is proven to be a cost-effective and time saving approach to improve the performance of hybrid electric vehicles (HEVs). This study focuses on modeling and parameter estimation of the longitudinal vehicle dynamics for Toyota Prius Plug-in Hybrid (PHEV) with power-split architecture. This model is needed to develop and evaluate various controllers, such as energy management system, adaptive cruise control, traction and driveline oscillation control. Particular emphasis is given to the driveline oscillations caused due to low damping present in PHEVs by incorporating flexibility in the half shaft and time lag in the tire model.

All-wheel Drive (AWD) is a mature technology and most automobile manufacturers offer this feature on their vehicles. Improved traction, enhanced vehicle stability, and better handling are some of the key characteristics of AWD vehicles which are achieved by distributing the appropriate level of torque to the front and rear axles. Accurately capturing the torque split between the two axles is essential for sizing of driveline components like gears, bearings, and shafts. Traditionally, the torque split is considered to be either 50-50%, or solely proportional to the static weight distribution between the two axles. Design decisions are made based on historical test data. In this paper a longitudinal vehicle dynamics model for AWD systems is proposed to understand the influence of various key factors such as dynamic weight transfer, compliance of driveline components, and changing tire radius on the torque split.

Today, an increasing emphasis is being placed on vehicle transient operation improvement to accomplish better drivability and lower emission and fuel consumption. In this regard, dynamic simulatory model of powertrain-vehicle is a stepping-stone on the path to achieve this goal. In this study, a complete powertrain-vehicle model has been developed to predict vehicle performance and fuel consumption, with careful attention given to the engine dynamics (dynamic of air and fuel flows into the intake manifold, and crankshaft transient response). The model has been experimentally identified and validated for “Paykan 1600i”. Since there is a good agreement between vehicle test and simulation results, the model proposed in this study can be used in design and performance evaluation of vehicle powertrain system.

This paper describes a methodology to estimate longitudinal velocity of a 4-wheel-drive electric vehicle, in which wheel driven torque can be independently controlled by electric motor. Without non-driven wheels it would be difficult to estimate the vehicle longitudinal velocity precisely, especially when all of four wheels have large slip ratio. Therefore, an estimation methodology based on fuzzy logic is put forward, which uses four wheel speed and longitudinal acceleration as input signals. However, this method works not very well when two or more wheels have large slip ratio. In order to improve estimation effect, a state variable filter is designed to calculate wheel acceleration signals, which are used as additional signals to the fuzzy logic observer. Furthermore, the possibility of using four wheel driving torque signals to improve the estimation precision is also discussed.