Fluid injection device for high-pressure systems

Screw activated device, consisting of a compressor, shielded replaceable ampules, a multiple-element rubber gland, and a specially constructed fluid line fitting, injects measured amounts of fluids into a pressurized system. It is sturdy and easily manipulated

Pedestrian demand modelling of large cities: an applied example from London

This paper introduces a methodology for the development of city wide pedestrian demand models and shows its application to London. The approach used for modelling is Multiple Regression Analysis of independent variables against the dependent variable of observed pedestrian flows. The test samples were from manual observation studies of average total pedestrian flow per hour on 237 sample sites. The model will provide predicted flow values for all 7,526 street segments in the 25 square kilometres of Central London. It has been independently validated by Transport for London and is being tested against further observation data. The longer term aim is to extend the model to the entire greater London area and to incorporate additional policy levers for use as a transport planning and evaluation tool

A Life-Cycle Overlapping-Generations Model of the Small Open Economy

In this paper we construct an overlapping generations model for the small open economy incorporating a realistic description of the mortality process. With agedependent mortality, the typical life-cycle pattern of consumption and saving results from the maximizing behaviour of individual households. Our ?Blanchard-Yaari-Modigliani?model is used to analytically study a number of typical shocks affecting the small open economy, namely a balanced-budget public spending shock, a temporary Ricardian tax cut, and an interest rate shock. The demographic details matter a lot?both the impulse-response functions and the welfare profiles (associated with the different shocks) are critically affected by them. These demographic details furthermore do not wash out in the aggregate. The model is flexible and can be applied to a wide variety of theoretical and policy issues.

An airborne remote sensing system for urban air quality

Several NASA sponsored remote sensors and possible airborne platforms were evaluated. Outputs of dispersion models for SO2 and CO pollution in the Washington, D.C. area were used with ground station data to establish the expected performance and limitations of the remote sensors. Aircraft/sensor support requirements are discussed. A method of optimum flight plan determination was made. Cost trade offs were performed. Conclusions about the implementation of various instrument packages as parts of a comprehensive air quality monitoring system in Washington are presented

Intergenerational Risk Sharing, Pensions and Endogenous Labor Supply in General Equilibrium

In the context of a two-tier pension system, with a pay-as-you-go first tier and a fully funded second tier, we demonstrate that a system with a defined wage-indexed second tier performs strictly better than one with a defined contribution or defined real benefit second tier. The former completely separates systematic redistribution (confined to the first tier) from intergenerational risk sharing (the role of the second tier). This way labor supply is undistorted.funded pensions, risk sharing, overlapping generations, endogenous labour supply

Integral assessment of urban conglomeration versus centre-periphery maglev rail systems under market imperfections

New transport infrastructure has a myriad of short and long run effects. The effects on population and economic activity are most difficult to estimate. This paper introduces three different models to estimate the impacts of new infrastructure on labour supply and demand, and carefully explains how the interaction between the models and their outcomes should be handled. A commuter location model is developed to estimate the impact of enabling longer commuting ranges within the same commuting time on housing migration. A spatial general equilibrium model (RAEM) is developed to estimate the impacts of increased spatial competition on firms and spatial production choices. The commuter location model is then used again to estimate the residential choices of the subsequent labour migration. Finally, an interregional commuter expenditure multiplier matrix is constructed to estimate the employment effects of both housing and labour migration. The methodology developed is applied to four Transrapid (magnetic levitation rail) proposals, each following a different route within the Netherlands. The empirical outcomes show remarkable patterns of effects and differences in effects, which were not expected beforehand but be explained quite well. Thus important new insights into the spatial pattern of indirect effects of new infrastructure in general are provided.

Integral cost-benefit analysis of Maglev technology under market imperfections

The aim of this article is to assess a proposed new mode of guided high speed ground transportation, the magnetic levitation rail system (Maglev), and to compare the results of a partial cost-benefit analysis with those of an integral CBA. We deal with an urbanconglomeration as well as a core-periphery Maglev project and also try to explain why the older German Maglev proposal to connect two large, but distant cities (Hamburg and Berlin) was rejected. The empirical outcomes of our study provide policy information on the interregional redistribution of working population and labor demand and whether these projects are worthwhile in terms of national welfare. They also show that the additional economic benefits due to market imperfections vary from –1% to +38% of the direct transport benefits, depending on the type of regions connected and the general condition of the economy. Hence, a uniform ‘additional to direct benefit’ ratio does not exist.

Calculating photonic Green's functions using a non-orthogonal finite difference time domain method

In this paper we shall propose a simple scheme for calculating Green's functions for photons propagating in complex structured dielectrics or other photonic systems. The method is based on an extension of the finite difference time domain (FDTD) method, originally proposed by Yee, also known as the Order-N method, which has recently become a popular way of calculating photonic band structures. We give a new, transparent derivation of the Order-N method which, in turn, enables us to give a simple yet rigorous derivation of the criterion for numerical stability as well as statements of charge and energy conservation which are exact even on the discrete lattice. We implement this using a general, non-orthogonal co-ordinate system without incurring the computational overheads normally associated with non-orthogonal FDTD. We present results for local densities of states calculated using this method for a number of systems. Firstly, we consider a simple one dimensional dielectric multilayer, identifying the suppression in the state density caused by the photonic band gap and then observing the effect of introducing a defect layer into the periodic structure. Secondly, we tackle a more realistic example by treating a defect in a crystal of dielectric spheres on a diamond lattice. This could have application to the design of super-efficient laser devices utilising defects in photonic crystals as laser cavities.Comment: RevTex file. 10 pages with 8 postscript figures. Submitted to Phys Rev

LM cathode thruster system Quarterly progress report, 4 Oct. 1969 - 4 Jan. 1970

Optimization testing of thermally integrated liquid mercury cathode thruster syste