To test simulation models of pedestrian flows, we have performed experiments for corridors, bottleneck areas, and intersections. Our evaluations of video recordings show that the geometric boundary conditions are not only relevant for the capacity of the elements of pedestrian facilities, they also influence the time gap distribution of pedestrians, indicating the existence of self-organization phenomena. After calibration of suitable models, these findings can be used to improve design elements of pedestrian facilities and egress routes. It turns out that "obstacles" can stabilize flow patterns and make them more fluid. Moreover, intersecting flows can be optimized, utilizing the phenomenon of "stripe formation." We also suggest increasing diameters of egress routes in stadia, theaters, and lecture halls to avoid long waiting times for people in the back, and shock waves due to impatience in cases of emergency evacuation. Moreover, zigzag-shaped geometries and columns can reduce the pressure in panicking crowds. The proposed design solutions are expected to increase the efficiency and safety of train stations, airport terminals, stadia, theaters, public buildings, and mass events in the future. As application examples we mention the evacuation of passenger ships and the simulation of pilgrim streams on the Jamarat bridge. Adaptive escape guidance systems, optimal way systems, and simulations of urban pedestrian flows are addressed as well.

https://pubsonline.informs.org/doi/pdf/10.1287/trsc.1040.0108

Self-Organized Pedestrian Crowd Dynamics: Experiments, Simulations, and Design Solutions

Thermal cameras are passive sensors that capture the infrared radiation emitted by all objects with a temperature above absolute zero. This type of camera was originally developed as a surveillance and night vision tool for the military, but recently the price has dropped, significantly opening up a broader field of applications. Deploying this type of sensor in vision systems eliminates the illumination problems of normal greyscale and RGB cameras. This survey provides an overview of the current applications of thermal cameras. Applications include animals, agriculture, buildings, gas detection, industrial, and military applications, as well as detection, tracking, and recognition of humans. Moreover, this survey describes the nature of thermal radiation and the technology of thermal cameras.

/pdf/thermal-cameras-and-applications-a-survey-4wd1xvg4uy.pdf

Thermal cameras and applications: a survey

A portable ultrasound imaging system includes a scan head coupled by a cable to a portable battery-powered data processor and display unit. The scan head enclosure houses an array of ultrasonic transducers and the circuitry associated therewith, including pulse synchronizer circuitry used in the transmit mode for transmission of ultrasonic pulses and beam forming circuitry used in the receive mode to dynamically focus reflected ultrasonic signals returning from the region of interest being imaged.

Portable ultrasound imaging system

This thesis describes the developement of a new type of simulation tool for the assessment of designs of public transport facilities (stations, airports) and other public spaces with intensive pedestrian flows. Since the available space for such facilities is increasingly under pressure, the space efficiency and walking comfort is becoming more and more important. The developed simulation tool provides designers and decision-makers with all kinds of quantitative information about the expected quality of pedestrian (traffic) flows such as travel times, waiting times, queue building, preferred routes, visits to shops and counters, etc. This information is very useful in comparing multiple designs as well as to optimise a specific design. The simulation model also is meant to improve schedules of public transport services at interchange nodes by minimising passenger transfer times. To that end, special attention is paid to the modelling of boarding and alighting processes. New insights about walking have been gained by performing unique large-scale laboratory experiments in which large groups of subjects were assigned various walking tasks, such as high volume crossing flows and walking through bottlenecks until flow breaks down. Specific walking and route choice models are developed using observations of passengers on platforms (such as in Delft) and route choice through the station (such as in Delft and Breda). The tool has proven its value in the analysis of new designs of the future Rotterdam Central Station and performance tests of the new Breskens-Vlissingen ferry terminals.

/pdf/modelling-passenger-flows-in-public-transport-facilities-3enw2n7w9b.pdf

Modelling passenger flows in public transport facilities

This paper discusses the development of a 64-element 35-MHz composite ultrasonic array. This array was designed primarily for ocular imaging applications, and features 2-2 composite elements mechanically diced out of a fine-grain high-density Navy Type VI ceramic. Array elements were spaced at a 50-micron pitch, interconnected via a custom flexible circuit and matched to the 50-ohm system electronics via a 75-ohm transmission line coaxial cable. Elevation focusing was achieved using a cylindrically shaped epoxy lens. One functional 64-element array was fabricated and tested. Bandwidths averaging 55%, 23-dB insertion loss, and crosstalk less than -24 dB were measured. An image of a tungsten wire target phantom was acquired using a synthetic aperture reconstruction algorithm. The results from this imaging test demonstrate resolution exceeding 50 /spl mu/m axially and 100 /spl mu/m laterally.

Development of a 35-MHz piezo-composite ultrasound array for medical imaging

Much progress has been made towards integrating the electronic circuitry associated with either linear or phased ultrasonic array scanning into the hand-held case of the transducer. The number of wires required to connect the transducer back to the display system has been dramatically reduced and the path length between transducer elements and the driver circuits kept to a few millimetres. To achieve this new construction, polymer transducer arrays have been fabricated and the pulse-control circuitry has been integrated onto custom-designed silicon chips.

An integrated multi-element array transducer for ultrasound imaging

The objective of this paper is to carry out a detailed analysis of the most popular connected components labeling (CCL) algorithms for binary images. This study investigates their usability for processing streaming data and suitability for implementation using Field-Programmable Gate Array (FPGA) devices. The first part of this paper presents the state of the art on CCL algorithms. Both capability for real-time video processing as well as memory requirements are taken into consideration. The second part of the paper describes an efficient implementation of the single pass labeling algorithm using a Virtex-II Pro FPGA. It is verified on the development board with an infrared camera module as a real-time video source. The system is capable of processing video stream with 640 x 480 pixels per frame at a speed of 30 fps limited by the bandwidth of the video source.

Comparative study on connected component labeling algorithms for embedded video processing systems.

Harmonic errors associated with the use of choppers in optical experiments

We present an approach that is intended for simple gesture control using a relatively inexpensive pyroelectric array detector. The detector is manufactured using standard wafer processing techniques. It consists of a 16 element passive infrared sensor array that responds to changing infrared signals, such as are generated by a hand moving at a distance of some tens of centimetres in front of the array. There is quite a large variation in the responsivity of the pixels within the array, but despite that it is relatively easy to use differential signals from the array or to apply a simplified version of an image processing algorithm to track movement in front of the detector. We have developed a prototype system that can recognise hand movements in different directions in front of the detector. This has allowed us to develop a demonstrator system that can be used to control, for instance, a PowerPoint presentation by gesture.

Recognition of Simple Gestures Using a PIR Sensor Array

Piezoelectric polymer materials are of interest for high frequency transducer array applications primarily because the array geometry can be achieved using photolithography. The UMIST research team have fabricated up to 64-element polymer transducer arrays. They have adopted a unique approach whereby the pulse control electronics can be mounted in close physical proximity with the transducer array. In order to accomplish this both transmit and receive circuitry has been integrated onto in-house custom designed silicon chip sets. A notable achievement is the design of a monolithic 16-channel programmable pulse generator chip fabricated in 1.5 mm CMOS technology. By employing novel design techniques time delays with 1 ns time resolution and a dynamic range of 219 have been achieved. A description of the system is provided and preliminary results of beam plotting measurements are given

Alistair Armitage

Papers

An integrated multi-element array transducer for ultrasound imaging

Comparative study on connected component labeling algorithms for embedded video processing systems.

Harmonic errors associated with the use of choppers in optical experiments

Recognition of Simple Gestures Using a PIR Sensor Array

Integrated ultrasound transducers