Recent Efforts and Experiments in the Construction of Aviation Engines

It became evident during World War I that ever-increasing demands were being placed on the mean power of aircraft engines as a result of the increased on board equipment and the demands of aerial combat. The need was for increased climbing efficiency and climbing speed. The response to these demands has been in terms of lightweight construction and the adaptation of the aircraft engine to the requirements of its use. Discussed here are specific efforts to increase flying efficiency, such as reduction of the number of revolutions of the propeller from 1400 to about 900 r.p.m. through the use of a reduction gear, increasing piston velocity, locating two crankshafts in one gear box, and using the two-cycle stroke. Also discussed are improvements in the transformation of fuel energy into engine power, the raising of compression ratios, the use of super-compression with carburetors constructed for high altitudes, the use of turbo-compressors, rotary engines, and the use of variable pitch propellers

Preliminary calculation of cylinder dimensions for aircraft engines

It is extremely important in building aircraft engines to determine the requisite cylinder dimensions as accurately as possible, in order that the weight required for a given power shall not be excessive. This report presents a calculation method that depends on the air requirement of the fuel

Grade Inflation, Social Background, and Labour Market Matching

A model is presented where workers of differing abilities and from different social backgrounds are assigned to jobs based on grades received at school. It is examined how this matching is affected if good grades are granted to some low ability students. Such grade inflation is shown to reduce the aggregate wage of the lower class workers because employers use social origin as a signal for productivity if grades are less than fully informative. Moreover, the high-ability students from the higher class may benefit from grade inflation since this shields them from the competition on the part of able students from the lower classes. --education,grading,standards,assignment,social mobility,grading,standards,assignment,social mobility

Political Uncertainty and Policy Innovation

Conventional wisdom has it that outside sources of information enhance the capability of political institutions to separate selfish from benevolent incumbents. This paper investigates, in the presence of innovative public policies whose outcomes are uncertain, the role of outside information and shows that it is more involved than typically thought. While it is true that enhanced information helps in separating politicians, it also creates an externality that reduces the incentives to experiment with innovative public policies.Policy uncertainty; Political uncertainty; Fiscal federalism;Policy innovation; Experimentation.

POLICY INNOVATION IN FEDERAL SYSTEMS

Conventional wisdom has it that policy innovation is better promoted in a federal rather than in a unitary system. Recent research, however, has provided theoretical evidence to the contrary: a multi-jurisdictional system is characterized---due to the existence of a horizontal information externality---by under-provision of policy innovation. This paper presents a simple model that introduces political competition for federal office. Under such competition political actors use the innovative policies in order to signal ability to the electorate. In the equilibrium analyzed policy innovation occurs more frequently than in a unitary system. It is thus shown that, once electoral motives are accounted for, the conventional wisdom is validated.Fiscal federalism; policy innovation; policy experimentation.

Technical Report: Distribution Temporal Logic: Combining Correctness with Quality of Estimation

We present a new temporal logic called Distribution Temporal Logic (DTL) defined over predicates of belief states and hidden states of partially observable systems. DTL can express properties involving uncertainty and likelihood that cannot be described by existing logics. A co-safe formulation of DTL is defined and algorithmic procedures are given for monitoring executions of a partially observable Markov decision process with respect to such formulae. A simulation case study of a rescue robotics application outlines our approach.Comment: More expanded version of "Distribution Temporal Logic: Combining Correctness with Quality of Estimation" to appear in IEEE CDC 201