Rolling of asymmetric disks on an inclined plane

In a recent papers, Turner and Turner (2010 {\em Am. J. Phys.} {\bf 78} 905-7) and Jensen (2011 {\em Eur. J. Phys.} {\bf 32} 389-397) analysed the motion of asymmetric rolling rigid bodies on a horizontal plane. These papers addressed the common misconception that the instantaneous point of contact of the rolling body with the plane can be used to evaluate the angular momentum $\mathbf L$ and the torque $\boldsymbol\tau$ in the equation of motion $d\mathbf L/dt = \boldsymbol\tau$. To obtain the correct equation of motion, the "phantom torque" or various rules that depend on the motion of the point about which $\mathbf L$ and $\boldsymbol\tau$ are evaluated were discussed. In this paper, I consider asymmetric disks rolling down an inclined plane and describe the most basic way of obtaining the correct equation of motion; that is, to choose the point about which $\mathbf L$ and $\boldsymbol\tau$ are evaluated that is stationary in an inertial frame

Recent Efforts Enabling Martian Rotorcraft Missions

The Mars Helicopter (MH), launching as a part of the Mars 2020 mission, will begin a new era of planetary exploration. Mars research has historically been conducted through landers, rovers, and satellites. As both government and private industries prepare for human exploration of the Martian surface within two decades, more in depth knowledge of what awaits on the surface is critical. Planetary aerial vehicles increase the range of terrain that can be examined, compared to traditional landers and rovers and have more near surface capability than orbiters. The Jet Propulsion Laboratory (JPL) and NASA Ames are currently exploring possibilities for a Mars Science Helicopter (MSH), a second-generation Mars rotorcraft with the capability of conducting science investigations independently of a lander or rover (although this type of vehicle could also be used assist rovers or landers in future missions). Preliminary designs of coaxial-helicopter and hexacopter configurations have targeted the minimum capability of lifting a payload in the range of two to three kilograms with an overall vehicle mass of approximately twenty kilograms. These MSH designs sizes are constrained by the aeroshell dimensions(currently focused on employing legacy Pathfinder or MSL aeroshells), rather than vehicle structural or aeroperformance limitations. Feasibility of the MSH configurations has been investigated considering packaging/deployment, rotor aerodynamics, and structural analysis studies. Initial findings suggest not only the overall feasibility of MSH configurations but also indicate that improvements up to 11.1 times increase in range or 1.3 times increase in hover time might be achievable, even with an additional science payload, compared to the current design of the MH

Sensitivity of the South Asian monsoon to elevated and non-elevated heating

Elevated heating by the Tibetan Plateau was long thought to drive the South Asian summer monsoon, but recent work showed this monsoon was largely unaffected by removal of the plateau in a climate model, provided the narrow orography of adjacent mountain ranges was preserved. There is debate about whether those mountain ranges generate a strong monsoon by insulating the thermal maximum from cold and dry extratropical air or by providing a source of elevated heating. Here we show that the strength of the monsoon in a climate model is more sensitive to changes in surface heat fluxes from non-elevated parts of India than it is to changes in heat fluxes from adjacent elevated terrain. This result is consistent with the hypothesis that orography creates a strong monsoon by serving as a thermal insulator, and suggests that monsoons respond most strongly to heat sources coincident with the thermal maximum.Engineering and Applied Science

How Does Uncertainty in Economic Policy React to Oil Price Shocks in Australia?

After the financial crisis and during the recession, the concept of economic policy uncertainty (EPU) received a significant amount of attention from researchers and policymakers. The variations in the uncertainties of such policies have been found to have a strong impact on certain economic factors, such as investments and inflation. Investors are most affected by this uncertainty, as they have no clear idea how their investment decisions will impact the economy. In light of this, the researcher has designed this study to explore and analyze the impact of oil price shocks (OPS) in Australia on EPU. Two categories of OPS have been taken into account: oil supply shocks (OSS) and oil shocks (OS) as a result of global demand (GD). The data collected in this study is a time series that covers a period of 28 years in total. Following the data collection, the researcher applied different techniques and tests—the most important of which was a Vector Auto Regression (VAR) model. The results of the current study, which were obtained through the application of a VAR model, indicate that the impact of OPS on EPU varies depending on the time period. In the short-term, the impact is positive; however, in the medium-term, the impact becomes negative and, in the long-term, this impact becomes positive and significant agai