A New Challenge: Testing the Video Course

This paper offers some preliminary thoughts on the testing ofvideo courses, including a review of the literature and an examinationof the research on the subject. The unique characteristics ofvideo courses suggest that different language learning outcomes maybe expected, which means that creating appropriate tests is thereforea new challenge for language teachers. The paper lists subtesttypes, and gives an example of a test used by the authors. Based onthis experience, a number of guidelines are offered regarding thecreation of appropriate tests, and a direction for future research inthe area is suggested

Open to Ideas: Information flows from Dairy Directions to Dairy Farmers

The ‘openness’ of farming systems that is the focus of this paper is ‘open to information’, in particular the way that new information from the farming systems research project, Dairy Directions, flows from research outputs to dairy farmers. Dairy Directions is a multidisciplinary research activity centred on a steering group of interested parties, mostly farmers, scientists and economists, but also drawing on extension agents, natural resource managers, water service providers, community service providers and public policy participants. The core general research question of Dairy Directions is ‘What options do farmers running different dairy farming systems have to achieve their goals in an uncertain future?’ The goals analysed by the project are predominantly economic and financial – maintaining or increasing profit and cash flow, growing wealth, managing risk, preparing for succession and balancing the dairy work-life balance. Their uncertain future encompasses variability in prices, as well as the natural environment and the policy setting.Farm Management,

A law of the iterated logarithm for Grenander's estimator

In this note we prove the following law of the iterated logarithm for the Grenander estimator of a monotone decreasing density: If $f(t_0) > 0$, $f'(t_0) < 0$, and $f'$ is continuous in a neighborhood of $t_0$, then \begin{eqnarray*} \limsup_{n\rightarrow \infty} \left ( \frac{n}{2\log \log n} \right )^{1/3} ( \widehat{f}_n (t_0 ) - f(t_0) ) = \left| f(t_0) f'(t_0)/2 \right|^{1/3} 2M \end{eqnarray*} almost surely where $M \equiv \sup_{g \in {\cal G}} T_g = (3/4)^{1/3}$ and T_g \equiv \mbox{argmax}_u \{ g(u) - u^2 \} ; here ${\cal G}$ is the two-sided Strassen limit set on $R$. The proof relies on laws of the iterated logarithm for local empirical processes, Groeneboom's switching relation, and properties of Strassen's limit set analogous to distributional properties of Brownian motion.Comment: 11 pages, 3 figure

A Comparison of Inlet Valve Operating Strategies in a Single-Cylinder Spark-Ignition Engine

This experimental work was concerned with comparison of inlet valve actuation strategies in a thermodynamic single cylinder spark ignition research engine equipped with a mechanical fully variable valvetrain on both the inlet and exhaust. The research involved study of the effects of the valvetrain on combustion, fuel economy and emissions when used to achieve variable valve timing alone and when applied together with early inlet valve closing for so-called unthrottled operation. The effects of such early inlet valve closure were examined using either fully variable events or by simulating two-stage cam profile switching. While fully variable operation enabled the maximum fuel savings over the widest operating map, it was apparent that two-stage switching mechanisms can provide an attractive compromise in terms of cost versus CO 2 benefit on engines of moderate to large capacity. However, from speed-load maps obtained in the current study it would appear that a wide range of inlet valve durations would be necessary to obtain fuel savings sufficient to warrant a system any more sophisticated than current variable valve timing mechanisms in future aggressively downsized gasoline engines. © IMechE, 2009

Feedback Synthesis for Controllable Underactuated Systems using Sequential Second Order Actions

This paper derives nonlinear feedback control synthesis for general control affine systems using second-order actions---the needle variations of optimal control---as the basis for choosing each control response to the current state. A second result of the paper is that the method provably exploits the nonlinear controllability of a system by virtue of an explicit dependence of the second-order needle variation on the Lie bracket between vector fields. As a result, each control decision necessarily decreases the objective when the system is nonlinearly controllable using first-order Lie brackets. Simulation results using a differential drive cart, an underactuated kinematic vehicle in three dimensions, and an underactuated dynamic model of an underwater vehicle demonstrate that the method finds control solutions when the first-order analysis is singular. Moreover, the simulated examples demonstrate superior convergence when compared to synthesis based on first-order needle variations. Lastly, the underactuated dynamic underwater vehicle model demonstrates the convergence even in the presence of a velocity field.Comment: 9 page

An experimental investigation of the aerodynamics of a NACA 64A010 airfoil-flap combination with and without flap oscillations. Part 1: Steady-state characteristics

A NACA 64A010 airfoil with a sealed-gap 1/4-chord flap was tested between splitter plates in the NASA Ames 11- by 11-Foot Transonic Wind Tunnel at Mach numbers from 0.50 to 0.85, and Reynolds numbers based on chord from 3 to 13 million. Although the main purpose of the test was to obtain unsteady pressure data with the flap oscillating, no unsteady data are presented in this paper. The steady-state data are presented and compared with other test data to provide a basis for evaluating the results. Pressure data at two span stations are used to deduce early boundary-layer transitions at the midspan at higher Mach numbers, angles of attack, and flap angles. The effects of flap angle on pressures, normal force, pitching moment, and hinge moment are also presented in the report. Mach number errors caused by the splitter-plate configuration and the angle of attack are evaluated using pressure measurements near the floor and ceiling of the wind tunnel