Detector activity

FIRE SIMULATOR predicts the effects of fire growth in a 1-room, 2-vent compartment with sprinkler and detector. It predicts temperature and smoke properties (Oj/CO/COj concentrations and optical densities), heat transfer through room walls and ceilings, sprinkler/heat and smoke detector activation time, heating history of sprinkler/heat detector links, smoke detector response, sprinkler activation, ceiling jet temperature and velocity history (at specified radius from the flre i, sprinkler suppression rate of fire, time to flashover, post-flashover burning rates and duration, doors and windows which open and close, forced ventilation, post-flashover ventilation-limited combustion, lower flammability limit, smoke emissivity, and generation rates of CO/CO, pro iri i post-flashover. 

Air-sampling detector Actively and continuously samples the air from a protected space and is able to sense the pre-combustion stages of incipient fire. 

Tests conducted with the propellant build-up configuration in the ignition end of the conveyor resulted in more erratic and aggressive burning reactions than observed in Stage one tests. Approximately 60 pounds of MISP was used for each test. For these tests, aluminum rupture discs 0.0008-inch thick were used on each pressure relief vent. One IR detector activating the sprinkler system was located in No. 1 (see Figure 4) position. 

As a general rule the mobile phase should not be detector-active, i.e. it should not have a property which is used for detection (exception indirect detection, see Section 6.9). Otherwise it is very possible that unwanted baseline effects and extra peaks will show up in the chromatogram. However, this recommendation cannot be followed in the case of bulk-property detectors such as the refractive index detector. 

If the peak becomes smaller with every blind injection there is a high probability of sample carry over. Measures as explained above under Sample Carry Over . If the peak appears with more or less constant size it may be an injection peak (system peak). Measures can be difficult or impossible. The mobile phase must not be detector-active, i.e. the UV cutoff wavelength must be taken into consideration. Perhaps the peak disappears when a mobile phase from another batch or another manufacturer is used, especially in low UV and with acetonitrile or trifluoroacetic acid. Injected air can produce a peak. ... 

Consider a thermopile infrared detector having an active surface area A and initially at the ambient temperature Tea (Fig. 3P-5). The active sensing element (or, active junction, equivalently) of the detector consists of two very tbmlayers (Si+52 10 5 cm) of bismuth and tellurium formed by vacuum deposition onto a film of Mylar. The upper surface is suddenly subjected to a heat flux of q" [W/m2]. The heat transferred from the detector to a sink at a temperature rsittk via a connection may be approximated as Q = Qo(T — T ) [W], where Qq is a known quantity and T is the temperature of the detector active junction-... 

For a lumped detector active junction (bismuth and tellurium layers of thickness 5-1 and 82, respectively, and surface area. 4), neglecting the conductive loss to the Mylar as well as the convective and radiative losses to the ambient, determine (a) the steady temperature, (b) the unsteady temperature, and (c) the time constant of the thermopile. 

If barriers of extinguishing agents are used, the agent is injected within a few milliseconds into the flame front. The injection is triggered by a flame detector. In case of doors the flame detector activates their closing function. The effectiveness of the measures must be demonstrated experimentally. 

This is actually the increase of the dark current due to illumination and is a dc value (valid for/= 0 Hz). Here rj denotes the quantum efficiency of the detector, < ) is the incident photon flux density, A is the detector active area. The factor T denotes the photoelectric gain or photogain (the ratio between the number of electrons flowing through the electric circuit and the number of absorbed photons). The fundamental equation of photoconductivity is also valid without changes for the short circuit current of a photovoltaic detector (photodiode operating in photo-conductive mode). In that mode of operation T = 1 in most of the cases. 

In the case when the surface of the detector receiving the incident optical flux is not equal to the detector active area, i.e., when some kind of concentrator is used to collect radiation from a larger area and direct it to the active area, a factor of optical concentration [8] may be formally introduced into the expression for the specific detectivity. This factor is equal to the square root of the ratio between the optical and active ( electrical ) detector area. 

We denote as optical or equilibrium methods all various procedures that increase the number of photons of the useful signal within the detector active area. This means that they improve the performance of photonic MWIR or LWIR detectors without causing a nonequilibrium between charge carriers and the semiconductor crystal lattice. 

Since the properties of metamaterials and metamaterial-containing structores can be engineered almost at wiU, an obvious question that occurs is if it is possible to use them as superior impedance matching structures. The problem reduces to the use of metamaterials as impedance matching stmctores between the surrounding medium and the material of the detector-active region. 

The cadmium molar fraction of the photodetector was x = 0.165, which is the optimum for the operation at 300 K. The detector-active area was assumed to be 1 mm X 1 mm, one of the standard dimensions for uncooled HgCdTe photoconductors for the detection of CO2 laser radiation. The bias voltage was 1.5 V, and the detector resistance 50 Q.. 

The whole concept of extraction photodiodes poses a practical problem, since the requirement exists that the active region thickness must be smaller than the diffusion length. Such a requirement poses design restrictions regarding the absorption path and the total detector active area. One of the approaches utilized to solve the above problem was not to use a single detector but rather a densely packed matrix of separate elements with lateral contacts on a joint substrate and with a joint exclusion junction (Fig. 3.28a) [376]. 

DETACT-QS, (US) Evans, D. D. Stroup, D. W. Calculates thermal detector activation time under unconfined ceilings, arbitrary fire [26]... 

E (dis/sec count/sec), is known at a time t after irradiation, the detector activity becomes... 

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