Development of welding techniques and filler metals for high strength aluminum alloys second quarterly report, 1 oct. - 31 dec. 1964

Welding techniques and filler metals for high strength aluminum alloys evaluated by bulge test progra

A Test of Congressional Voting on Immigration Restrictions

Immigration policy is supplied endogenously through a political process that weighs the impacts of immigration on factor owners, together with other interests, in determining policy outcomes. The relative significance of constituent interests and legislator ideology in shaping policy is tested by identifying the correlates of congressional voting on immigration legislation. Conservative lawmakers are found to generally support stricter immigration controls. Legislators representing border states and urban areas favor looser restrictions, possibly reflecting the political influence of recent immigrants. There is evidence that immigration reform is a normal good and that substitutability between native and immigrant labor promotes tighter immigration restrictions

Profitable chemical-free cowpea storage technology for smallholder farmers in Africa: opportunities and challenges

Cowpea is the most economically and nutritionally important indigenous African grain legume, grown by millions of resource-poor farmers. It is a key cash crop in areas too dry to grow cotton or other export crops. Most of the over 3 million t of cowpea grain produced annually in West and Central Africa is grown on small farms. Storage is often identified as the key challenge for small scale cowpea growers. Many farmers sell cowpea grain at low harvest time prices rather than risk losses by bruchids during storage. Some traditional methods are effective for small quantities (e.g., 10 kg), but are difficult to scale up. Some effective storage chemicals are available, but they are regularly misused by farmers and merchants. The Purdue Improved Cowpea Storage (PICS) Project is addressing these problems through promotion of hermetic storage in triple layer sacks which have an outer layer of woven polypropylene and two liners of 80 μ high-density polyethylene. Village demonstrations with more than 45, 000 PICS sacks have shown the technology to be effective. Good quality affordable sacks have been produced by manufacturers in Nigeria, Burkina Faso and Mali. Over the past three years more than one million sacks have been produced and sold. Despite the success with the outreach activities and the farmer adoption, the challenge remains to develop sustainable sack distribution networks. Issues identified include reluctance of wholesalers to order sacks due to risk associated with a new product, inability of wholesalers to develop effective distribution networks due to difficulties with enforcing contracts, and limited access to capital. The PICS project is exploring new ways to address some of these issues, including using non-traditional distribution systems for PICS sacks such as agro-dealers networks, and adapting distribution systems that have worked for cell phones and other products. Keywords: Cowpea, Bruchids, Hermetic storage, Supply chain, West and Central Afric

Employment prospects for agricultural graduates in Guinea Conakry

nemployment of graduates is a challenging problem in Africa, and it is aggravated by many factors such as population growth, mismatch between curriculum and employer needs, and lack of evidence-based policy making. In this context, the objectives of the present study are twofold. First, the aim is to identify key characteristics influencing labor market participation of graduates from agricultural higher education in Guinea. Second, the aim is to identify agricultural labor market needs in terms of skills and profiles desired by employers. Telephone surveys were administered to recent graduates from the main agricultural higher education institutions. The major findings from the analysis suggest that about one third of Guinean agricultural university graduates in the 2008-2013 period were employed in the formal sector in 2013-2014. Employment rates are lower for the technical schools. In terms of job creation prospects, key employers expect a doubling of hiring for positions requiring technical school or university training. Most of the projected growth is expected in the private sector. The results indicate that male graduates have a 7% higher probability of being employed as compared to female graduates in the aggregate analysis

A cloned linguistic decision tree controller for real-time path planning in hostile environments

AbstractThe idea of a Cloned Controller to approximate optimised control algorithms in a real-time environment is introduced. A Cloned Controller is demonstrated using Linguistic Decision Trees (LDTs) to clone a Model Predictive Controller (MPC) based on Mixed Integer Linear Programming (MILP) for Unmanned Aerial Vehicle (UAV) path planning through a hostile environment. Modifications to the LDT algorithm are proposed to account for attributes with circular domains, such as bearings, and discontinuous output functions. The cloned controller is shown to produce near optimal paths whilst significantly reducing the decision period. Further investigation shows that the cloned controller generalises to the multi-obstacle case although this can lead to situations far outside of the training dataset and consequently result in decisions with a high level of uncertainty. A modification to the algorithm to improve the performance in regions of high uncertainty is proposed and shown to further enhance generalisation. The resulting controller combines the high performance of MPC–MILP with the rapid response of an LDT while providing a degree of transparency/interpretability of the decision making

Systematic Experimental Evaluation of Aeroelastic Characteristics of a Highly Flexible Wing Demonstrator

This paper presents a comprehensive experimental analysis of the evolutionary modal characteristics of a highly flexible wing that exhibits bending–torsion coupling-driven instability. By implementing operational modal analysis on responses triggered by a combination of an external pulse-like stimulation and turbulence within the flow, this paper presents the airspeed-driven variations of the modal frequencies, damping ratios, and the underlying modal coupling behavior, leading to instability. This analysis is extended to varying the wing root pitch angles through which the effects of geometrical nonlinearity are exercised. Their effects are particularly noted on the hump feature of the airspeed-driven damping ratio locus of the mode responsible for instability. The decreasing critical damping ratio is shown to result in amplified turbulence-driven responses, which pose significant challenges to identification procedures by masking the visibility of other modes. Furthermore, through a novel technique used to analyze the modal coupling, the relative phase and magnitude properties of the coupled bending–torsion composition of the critical mode before and at flutter onset are evidenced experimentally. It is demonstrated that these relative participation measures provide a strong indication of the response content of the limit cycle oscillations that emerge after the flutter speed

Application of bifurcation methods for the prediction of low-speed aircraft ground performance

The design of aircraft for ground maneuvers is an essential part in satisfying the demanding requirements of the aircraft operators. Extensive analysis is done to ensure that a new civil aircraft type will adhere to these requirements, for which the nonlinear nature of the problem generally adds to the complexity of such calculations. Small perturbations in velocity, steering angle, or brake application may lead to significant differences in the final turn widths that can be achieved. Here, the U-turn maneuver is analyzed in detail, with a comparison between the two ways in which this maneuver is conducted. A comparison is also made between existing turn-width prediction methods that consist mainly of geometric methods and simulations and a proposed new method that uses dynamical systems theory. Some assumptions are made with regard to the transient behavior, for which it is shown that these assumptions are conservative when an upper bound is chosen for the transient distance. Furthermore, we demonstrate that the results from the dynamical systems analysis are sufficiently close to the results from simulations to be used as a valuable design tool. Overall, dynamical systems methods provide an order-of-magnitude increase in analysis speed and capability for the prediction of turn widths on the ground when compared with simulations. Nomenclature co = oleo damping coefficient, N s2 =m2 cz = tire vertical damping coefficient Fco = damping force in oleo due to the orifice,

Pushing Moral Buttons: The Interaction Between Personal Force and Intention in Moral Judgment

In some cases people judge it morally acceptable to sacrifice one person’s life in order to save several other lives, while in other similar cases they make the opposite judgment. Researchers have identified two general factors that may explain this phenomenon at the stimulus level: (1) the agent’s intention (i.e. whether the harmful event is intended as a means or merely foreseen as a side-effect) and (2) whether the agent harms the victim in a manner that is relatively “direct” or “personal”. Here we integrate these two classes of findings. Two experiments examine a novel personalness/directness factor that we call personal force, present when the force that directly impacts the victim is generated by the agent’s muscles (e.g., in pushing). Experiments 1a and b demonstrate the influence of personal force on moral judgment, distinguishing it from physical contact and spatial proximity. Experiments 2a and b demonstrate an interaction between personal force and intention, whereby the effect of personal force depends entirely on intention. These studies also introduce a method for controlling for people’s real-world expectations in decisions involving potentially unrealistic hypothetical dilemmas.Psycholog