Rollover Problem Research Articles

The Y2K problem and professional responsibility: a retrospective analysis

The Y2K problem was the single most expensive and baffling challenge to society and corporate management the world has faced in many decades. Notwithstanding dire predictions, fear of the malfunctioning of power systems, water supply systems, telecommunications systems, air traffic control systems, etc. did not materialize. The smooth transition to the new millennium led some people to claim that Y2K was a hoax in order to line the pockets of executives of computer and management consulting firms. In an effort to explain the Y2K-related disruptions, and how potential disasters were averted, this paper addresses the overall impact of Y2K, including the leap-year rollover problem, the hazards of Y2K, as well as the massive costs spent on preventing potential failures. In addition, seven causal factors of the Y2K problem are analyzed. Finally, three categories of lessons learned from Y2K are discussed: the management of information technology, the social responsibility of computer professionals, and a global threat warrants global cooperation.

A Worst-Case Evaluation Method for Dynamic Systems

A worst-case evaluation method is presented in this paper. The objective of this method is to identify worst-case disturbances so that the performance of dynamic systems under extreme conditions can be evaluated. Depending on the dynamics and information structure of the system, the worst-case evaluation problems are classified into four cases. Classical optimal control and game theories are used to construct algorithms to obtain linear solutions analytically. Numerical schemes to solve nonlinear worst-case problems are also presented. Two case study examples are then presented—a truck rollover problem and a vehicle stability controller evaluation problem. In both cases, a combined analytical-numerical method is used. The nonlinear plant is first linearized. The analytical solution of the linearized plant is then used as the initial guess for the numerical scheme. The final worst-case disturbance is then obtained iteratively from the numerical scheme. It was found that the proposed worst-case evaluation method is able to produce much larger unwanted plant motions (roll/side slip in the two case studies) compared with traditional evaluation maneuvers.

Tractor stability indicator

Tractor overturns are a major cause of death in farm operations. The oversturns are the result of interactions between the tractor operator, the tractor and the environment. Numerous variables involved in tractor overturn have been identified. Previous stability analyses have resulted in attempts to design devices to warn or prevent tractor rollover but to date nothing has proved successful. A newer approach to the rollover problem is to develop instrumentation that will give the operator instantaneous cues concerning the tractor's stability as it is operated. The device is perceived as a learning instrument which will increase both cognitive and motor skills.

Correction for background absorption and stray radiation in a.c. modulated Zeeman atomic absorption spectrometry

Analytical results are presented obtained with Zeeman atomic absorption (ZAA) using a modified sine wave magnetic field. The measurement at zero field strength is lengthened to 0.5 ms for a 50 Hz magnetic field of 10 kG. The a.c. Zeeman system is extended with an additional intensity measurement performed at an intermediate field strength. The three field Zeeman system (3FZAA) permits simultaneous correction for background absorption and stray radiation at the expense of halved analytical sensitivity. The background correction capabilities of ZAA and 3FZAA are the same. However, the 3FZAA signals show increased noise in comparison to ZAA. In the three field system the roll-over problem, inherent in existing Zeeman systems, is shifted to higher concentration and to higher absorbance. The height and the position of the maximum in ZAA and 3FZAA analytical curves do not depend on the amount of background absorption. A method for the extension of analytical curves in AA is presented. Utilizing an a.c. modulated magnetic field any sensitivity between zero and ordinary AA sensitivity can be obtained.