Constant net-time headway as key mechanism behind pedestrian flow dynamics

We show that keeping a constant lower limit on the net-time headway is the key mechanism behind the dynamics of pedestrian streams. There is a large variety in flow and speed as functions of density for empirical data of pedestrian streams, obtained from studies in different countries. The net-time headway however, stays approximately constant over all these different data sets. By using this fact, we demonstrate how the underlying dynamics of pedestrian crowds, naturally follows from local interactions. This means that there is no need to come up with an arbitrary fit function (with arbitrary fit parameters) as has traditionally been done. Further, by using not only the average density values, but the variance as well, we show how the recently reported stop-and-go waves [Helbing et al., Physical Review E, 75, 046109] emerge when local density variations take values exceeding a certain maximum global (average) density, which makes pedestrians stop.Comment: 7 pages, 7 figure

A precision sidereal telescope drive based on a solar time crystal clock

A requirement arose for a sidereal drive for a small microwave radiometer on an equatorial mount, the equipment to run unattended to a precision of about 2 minutes in hour angle over a 7-day period. The installation already included a solar-time crystal clock based on a IO MHz oscillator (type HCD 25), which through decade scalers could easily be arranged to operate a standard 50 Hz synchronous motor which would drive the mounting at one revolution per solar day. However, no suitable gearing was available to generate the required sidereal rate

Minnesota Agripower Project, Task IV research report

Economic analysis is being conducted by the Department of Applied Economics in support of Minnesota Alfalfa Producer`s development of alfalfa as a dedicated biomass feedstock for energy production. University Researchers have assisted in the development and implementation of inventory control systems and procedures. This report lists the tasks for which researchers are currently finalizing economic analysis. The tasks encompass three main areas: (1) optimization of feedstock transportation system, (2) analysis of market potential for new alfalfa products, and (3) total systems analysis

Generalized Centrifugal Force Model for Pedestrian Dynamics

A spatially continuous force-based model for simulating pedestrian dynamics is introduced which includes an elliptical volume exclusion of pedestrians. We discuss the phenomena of oscillations and overlapping which occur for certain choices of the forces. The main intention of this work is the quantitative description of pedestrian movement in several geometries. Measurements of the fundamental diagram in narrow and wide corridors are performed. The results of the proposed model show good agreement with empirical data obtained in controlled experiments.Comment: 10 pages, 14 figures, accepted for publication as a Regular Article in Physical Review E. This version contains minor change

Exploring the Effect of Crowd Management Measures on Passengers’ Behaviour at Metro Stations

To reduce problems of interaction at the platform train interface (PTI) platform edge doors (PEDs) and markings on the platform are used as door positions indicators. The common methods to study the effect of these measures are based on average values of density using Fruin’s Level of Service (LOS), however identification cannot be made of which part of the PTI is more congested. To solve this problem, a new method is proposed. The method included a conceptual model in which the PTI was discretised into 40 cm square cells to identify which part of the platform is more congested. Passengers’ behaviour was recorded considering two situations before the train arrives: i) passengers waiting in front of the doors; ii) passengers waiting beside the doors. Observation was done at existing stations at Metro de Santiago and London Underground. Results show that PEDs changed the behaviour of passengers as they were located beside the doors rather than in front of them. In addition, when markings were used on the platform, then this behaviour was reinforced. Therefore, it is recommended to use this method to better design the PTI rather than the LOS which is used to design the whole platform. Further research is needed to study the effect of PEDs on passengers with reduced mobility

The Fundamental Diagram of Pedestrian Movement Revisited

The empirical relation between density and velocity of pedestrian movement is not completely analyzed, particularly with regard to the `microscopic' causes which determine the relation at medium and high densities. The simplest system for the investigation of this dependency is the normal movement of pedestrians along a line (single-file movement). This article presents experimental results for this system under laboratory conditions and discusses the following observations: The data show a linear relation between the velocity and the inverse of the density, which can be regarded as the required length of one pedestrian to move. Furthermore we compare the results for the single-file movement with literature data for the movement in a plane. This comparison shows an unexpected conformance between the fundamental diagrams, indicating that lateral interference has negligible influence on the velocity-density relation at the density domain $1 m^{-2}<\rho<5 m^{-2}$. In addition we test a procedure for automatic recording of pedestrian flow characteristics. We present preliminary results on measurement range and accuracy of this method.Comment: 13 pages, 9 figure

An Upper Limit to Microwave Pulse Emission at the Onset of a Supernova

This paper reports an upper limit at 10 GHz of 4 x 10^(43) erg in a 40 MHz bandwidth for the microwave pulse emission at the onset of an optically observed supernova

A Search for Isolated Microwave Pulses from the Perseus Cluster of Galaxies

The paper describes a search for prompt microwave emissions from supernovae in the central region of the Perseus cluster of galaxies, using a coincidence technique involving five tracking radiometers located at widely spaced sites. No coincidences were found between January and December, 1973, and no supernovae were reported during this period from the optical surveys, in that region of sky

Transportation research needs and issues for Chinese agriculture

Interprovincial circulation of grain and wholesale markets in China / Wu Shuo -- Inter-state/province grain transportation in the U.S. and China / Tenpao Lee, Robert J. Hauser, Stanley R. Thompson, and Barbara J. Hrutka -- Methodology and data systems for study of transportation / Won W. Koo and Jerry Fruin -- An application of a spatial equilibrium model to analyze the impact on China's trade of a policy change / Shwu-Eng H. Webb, Catherine K. Halbrendt, Rajaram Gana, and Francis Tuan -- Possible Joint Chinese and U.S. grain transportation and distribution research opportunities / Roland R. Robinson and Donald W. Larson -- Transportation research needs and issues for Chinese agriculture: discussion of session presentations / Dale G. Anderso