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We develop a method for the loading of ground by moving vehicles in large finite-difference time-domain simulations of seismic wave propagation. The objective is to realistically produce two distinct types of ground loading for either wheeled or tracked vehicles in our propagation models: lower frequency loading associated with suspension dynamics and higher frequency impulsive loading associated with tire treads or wheels rolling over individual track blocks. These loading characteristics are important because field measurements show that vehicle ground forcing in both frequency bands produces seismic surface waves that networked sensors can remotely process for security applications. The method utilizes a vehicle-dynamics model to calculate a response to vehicle acceleration and ground features such as bumps; calculates forces transmitted to the ground; distributes these forces to staggered points of a finite-difference model; and simulates seismic wave propagation away from the vehicle. We demonstrate the method using bounce-and-pitch models of wheeled and tracked vehicles. We show that by carefully preprocessing force inputs, we can accurately simulate wave propagation and seismic signatures in finite-difference analyses of vehicles moving continuously over terrain. Index Terms--Finite-difference time-domain (FDTD) methods, modeling, seismic inverse problems, seismic signal processing, seismic waves, vehicles.

A novel adaptive control law for the end-effector tracking problem of underwater vehicle-manipulator systems (UVMSs) is presented in this paper. By exploiting the serial-chain kinematic structure of the UVMS, the overall control problem is decomposed in a set of elementary control problems, each of them formulated with respect to a single rigid body in the system. The proposed approach results in a modular control scheme which simplifies application to UVMSs with a large number of links, reduces the required computational burden, and allows efficient implementation on distributed computing architectures. Furthermore, the occurrence of kinematic and representation singularities is overcome, respectively, by expressing the control law in body-fixed coordinates and representing the attitude via the unit quaternion. To show the effectiveness of the proposed control strategy, a simulation case study is developed for a vehicle in spatial motion carrying a six-degree-of-freedom manipulator. Index Terms--Adaptive control, control of redundant manipulators, underwater robotics, virtual decomposition control.

With reference to road transport information (RTI) applications, such as cooperative driving, short-range intervehicle communications in a highway environment are investigated in this paper. The research in this field indicates the suitability of the 60-64-GHz band. Due to the distributed nature of the intervehicle communication system, an R-ALOHA protocol is considered; multihop (MH) and single-hop (SH) strategies are compared. Network performance is assessed by considering the joint impact of random access, interference, thermal noise, propagation, and packet capture effect. Several figures of merit are analyzed and discussed: packet success probability (PSP), system stabilization time (SST), first success time (FST), and deadline failure probability (DFP). Network performance is evaluated either by an analytical approach or by a software tool able to simulate a one-lane highway scenario. Both steady-state and transition situations are considered. System performance in terms of PSP (in the presence of two-ray Rice fading, noise, and interference with antenna diversity and selection combining) is analytically evaluated to validate the simulation tool and to prove the suitability of an MH network strategy. The simulation approach allows the evaluation of the impact of protocol parameters on network performance, with reference to nonsteady-state situations. Index Terms - Highway, intervehicle, millimeter waves, multihop.

A two-dimensional optimization process, which simultaneously adjusts the spark timing and equivalence ratio of a lean-burn, natural gas, Hercules G1600 engine, has been demonstrated. First, the three-dimensional surface of thermal efficiency was mapped versus spark timing and equivalence ratio at a single speed and load combination. Then the ability of the control system to find and hold the combination of timing and equivalence ratio that gives the highest thermal efficiency was explored. N[O.sub.x], CO, and HC maps were also constructed from our experimental data to determine the tradeoffs between efficiency and emissions. The optimization process adds small synchronous disturbances to the spark timing and air flow while the fuel injected per cycle is held constant for four cycles. The engine speed response to these disturbances is used to determine the corrections for spark timing and equivalence ratio. The control process, in effect, uses the engine itself as the primary sensor. The control system can adapt to changes in fuel composition, operating conditions, engine wear, or other factors that may not be easily measured. Although this strategy was previously demonstrated in a Volkswagen 1.7 liter light duty engine (Franklin et al., 1994b), until now it has not been demonstrated in a heavy-duty engine. This paper covers the application of the approach to a Hercules G1600 engine.

The North American auto marketplace witnessed a major restructuring during the 1980s. This article examines UAW's and CAW's quite different and distinctive responses to these developments at two union plants: the UAW's and GM's joint operation of the Saturn plant and the CAW's adversarial shop floor labor-management relations at CAMI, a GM-Suzuki joint venture. Then the article focuses on the common challenges both unions have to overcome in organizing Hyundai, the South Korean automaker, and the six Japanese plants. The article closes by exploring the risks and opportunities both unions face from the North American Free Trade Agreement., During the decade of the eighties, ten East Asian automobile assembly plants were built across the industrial heartland of North America from Smyrna, Tennessee to Bromont, Quebec.(1) This experience, rooted [...]

With the slackening world economy, growth in Sweden is slowing and will be limited to a modest 1.6 percent this year. Growth in Swedish exports is being held back primarily [...]

Developing electronically controlled, cleaner engines for use in heavy off-highway machinery is being assisted by advances made in the automotive industry.