Photoelectric Type Research Articles

High Sensitivity Prototype Kit with IoT System for Fire Detection in a Peatland Swamp Forest Area

Smoke sensor of the photoelectric type is often used in indoor fire detection system. It is very sensitive to fire smoke and will trigger a fire alarm quickly when the presence of smoke is detected.By making a small innovation, this sensor can be implemented outdoors by means of IoT as used in the forest fire early detection system. However, the typical use of the sensor without any modification causes the sensitivity of the system to be very low such as failing to identify the actual presence of smoke. To increase the sensitivity of systems that use this type of sensor, the developed system is equipped withan automatic reclosing operation that is able to distinguish real smoke or not. The system has been designed to trigger cloud servers only after detecting smoke for ten seconds or beyond. System equipped with automatic reclosing operation show better response by not triggering cloud servers when detecting temporary smoke from car, motorcycle or nearby factory. When comparing the system before and after using this operation is, it was found that the system no longer sends smoke notification message to the user via Telegram channel when this temporary smoke is detected

랙크식 물류창고 조기 화재감지를 위한 다중센서 복합형 화재감지기의 화재감지 성능에 관한 실험연구

This paper presents combined fire detector based on the multi-sensor for early stage fire detection of rack-type warehouse. The combined fire detector suggested in this paper consist of temperature sensor of thermistor, smoke sensor of photo-electric type and CO sensor of electrochemistry type. In order to verify fire detection performance of combined fire detector suggested in this paper fire experiment is conducted in real-scale rack structure. And response characteristics combined fire detector compare with conventional heat detector and smoke detector. The results show that combined fire detector in this paper is able to detect fire very quickly.

A Study on Response Characteristics of Photoelectric Type Smoke Detector Chamber Due to Dust Color

A Study on Response Characteristics of Photoelectric Type Smoke Detector Chamber Due to Dust Color

아날로그 광전식 연기감지기 비화재보 개선에 대한 연구

아날로그 광전식 연기감지기 비화재보 개선에 대한 연구

An All-Sky Photometer

DURING the period of the International Quiet Sun Year, better opportunities may be found for the examination of airglow in the middle latitudes at a time when little or no auroral contamination is expected. With the view of measuring the intensities of the night airglow radiations emitted from the whole dome of the sky, a simple photoelectric type of photometer has been designed and built, in the Upper Atmosphere Research Section of the National Research Council, Ottawa, Canada.

Tests and Adaptation of the Foxboro Dew-Point Recorder for Weather Observatory Use *

The new Foxboro dew-point recorder, “Dewcel,” which was built for air-conditioning control, has been adapted to meteorological use at Blue Hill Observatory and tested over a 21-month period. These tests indicate that a rugged recorder, having an accuracy within ± 3F° of that of an Assmann ventilated psychrometer in the natural wind (usually unstable conditions) is now available for station use. The moisture-sensitive element consists of two parallel electrical conductors with an A.C. potential of 25 volts between them, wound about a tube covered with wicking containing an excess of lithium chloride crystals. Dew point is indicated by the temperature of the cell as equilibrium between the ambient vapor pressure and lithium-chloride vapor pressure is maintained, rather than by the Diamond-Hinman principle of recording electrical resistance to maintain vapor-pressure equilibrium. A satisfactory shield for the sensitive element against wind, rain, snow and fog has been devised after considerable experiment. Other than re-doping the cell with a lithium-chloride solution every 90–100 days no servicing is required. Dry and wet thermocouple tests revealed rapid fluctuations of the dew point whenever the air is unstable; therefore, the lag of the instrument, 2 to 4 minutes to make 98% of the change to a sudden new value, is advantageous when dew points for synoptic purposes are required. Of the three general types of dew-point recorders the Foxboro Dewcel appears to be best for routine synoptic weather reports. The simpler mechanical type of thermal element and hair hygrometer linked has the disadvantages of several linkages and those inherent in the hair hygrometer. It is not readily adaptable to indicating or recording at a distance. Instruments maintaining a thermal element in a wetted condition fail during prolonged periods of freezing. The direct reading photoelectric type dew-point recorder operates over a wider range and with greater sensitivity although there is always an uncertainty between 15° and 32°F whether the dew or frost point is being measured. The photoelectric type requires special care and frequent attention during operation.

Recommendations Concerning the use of Portable Photometers: Recommendations concerning the Use of Portable Photometers, Particularly for Street Lighting Measurements

The following notes, drawn up by the Technical Committee of the Society, are intended to afford guidance in the use of portable photometric instruments. Attention may be drawn to the existing British Standard Specifications dealing with their construction and accuracy, No. 230, 1935 (Visual Type) and No. 667, 1936 (Photoelectric Type).

A DICHROMATIC PROJECTION MICROPHOTOMETER

A new type of microphotometer is described which combines the advantages of the projection type described by Hesthal and Harrison with those of the original photoelectric type of Koch. The plate being measured is traversed by a beam of blue light supplied from a small lamp of constant intensity, which is used to make the desired density determinations. At the same time it is viewed by means of a beam of orange light furnished by a projection lamp run on the commercial a.c. This arrangement eliminates errors sometimes present in projection type microphotometers due to light scattered from the optical system (Schwarzschild-Villiger Effect). Additional advantages claimed for the instrument are: high resolving power, due to the ease of correcting lenses for only two colors; great flexibility and stability of adjustment, due to the absence of microscope lenses and microscopic slits; high reserve sensitivity; high electrical stability, due to the fact that all light sources, photoc-ells, tubes, and batteries are running at from one-tenth to one-half normal capacity; ease of handling, due to the long, open, and linear scale and the use of a rugged galvanometer. It is possible to construct the instrument so that no battery furnishing more than six volts is needed. It can be used for automatic recording, but is particularly useful for direct reading work where specific lines are to be selected from a complex spectrum. The instrument is quite simple and inexpensive to construct.

PRELIMINARY NOTE ON THE APPLICATION OF THREE-ELEMENT VACUUM TUBES TO STELLAR PHOTOMETRY

The great sensitivity of three-element vacuum tubes as detectors and amplifiers of minute quantities of electrical energy has raised the question as to the possibility of using them to extend the sensitivity and accuracy of stellar photometers of the photoelectric type. A number of investigators have attempted to, use them in this way but so far as the writer is aware the results were very unsatisfactory when the light intensities were low enough to be of the order of star-light. The difficulty was due partly to the fact that until recently there was no satisfactory theory of the operation of vacuum tubes and in consequence most of the attempts to use them were without a firm engineering basis and resulted in great inefficiency of method. Furthermore, the older types of vacuum tubes were very imperfect and gave rise to unstable, erratic, and unreliable behavior. At present the theory of vacuum tubes has been worked out in great detail especially in their relation to radio and line communication, and with but slight changes can be applied to practically any electrical system. The modern vacuum tubes are manufactured with a high degree of precision, stability, and sensitivity. The present note is an attempt to present some of the simpler principles of vacuum tube in operation in connection with stellar photometry, as well as a few methods in which they may be used. The least amount of power taken in the most efficient form that can be accurately measured wtih a vacuum tube amplifier system is of the order of 1015 watts or IO8 ergs/sec. It is there-