Alarm rate

As the nuniber of motor scooters and motorcycles in Asia has grown at an alarming rate, policies to... 

At PicArsn (Ref 19), the fast neutron activation approach for detection of expls in suitcases was extended to the activation of both nitrogen and oxygen using two 7-ray detector stations in sequence. After 14 MeV neutron irradiation, the baggage is first monitored for 6.1 MeV 7-rays from the l60(n,p),6N reaction (7.5 sec half-life), followed by measurement of the 10 min 13N. Because expls are also rich in oxygen and have characteristic ratios of N/O, it was felt that this approach would increase the probability of detection with a corresponding decrease in the false alarm rate... 

When it comes to laboratory storage, it is safe to say that the space required is at least twice what a planner would estimate. Samples, reagents, and spare equipment will pile up at an alarming rate. To this should be added the fact that some items will have to be stored under controlled conditions and that valuable items will need to be kept in locked storage. Flammables, even in moderate amounts, need special storage. Since regulations vary from one area to another, this matter should be discussed with local fire department officials. 

A staggering number of papers are published each year in the literature on various candidate chemical/biological detection systems. Researchers and manufacturers make diverse claims of detection limits, sensitivity, false-alarm rates, and robustness for these systems. The committee believes that in many cases, researchers emphasize the strengths of their particular detection systems while minimizing or ignoring their flaws. This practice makes it virtually impossible to evaluate the likely performance of a detection system in real-world air transportation environments. 

For the detection of slow-acting biological agents (which may not produce symptoms for several days), the system response time would depend on the frequency of sampling and analysis. The frequency of sampling and analysis would be determined by factors such as the cost of the assay, the frequency with which critical reagents need to be replaced, the robustness of the detector, and so on. The minimum response time would be determined by the time required to collect a sample, prepare it for analysis, conduct the assay, and report the results. In the event of an alarm from a detector with a significant false-alarm rate, additional time would be required to determine its validity and to decide on an appropriate response. 

As a formal vehicle for communication, the serial journal appeared about 300 years ago in Britain and France [33]. Since that time the number of scientists, the number of research papers, and the number of scientific and professional journals have increased at a dramatic and, for many years, an alarming rate. It is estimated that by 1880 between 4500 and 5000 biomedical journals were being published [34]. The... 

In addition to sensitivity, an important feature for any biochemical sensor is selectivity, i.e., the ability to response to a specific chemical or agent. In additional to the obvious significance (reducing the false alarm rate, etc.), this ability is... 

Diabetes is a global epidemic affecting more than 240 million people worldwide. The incidence of this disease is growing at an alarming rate, with 380 million cases predicted by 2025. Each year over 3.8 million people die from complications of diabetes, including heart disease, stroke and kidney failure. The vast majority... 

To achieve early and reliable warnings of leakages, the sensitivity of detectors should be at the highest level commensurate with the level of false alarm rates. 

Inevitably, some of the explanations here have been over-simplified because physical chemistry is growing at an alarming rate, and additional sophistications in theory and experiment have yet to be devised. But a more profound reason for caution is in ourselves it is all too easy, as scientists, to say Now I understand when in fact we mean that all the facts before us can be answered by the theory. Nevertheless, if the facts were to alter slightly - perhaps we look at another kind of nut - the theory, as far as we presently understand it, would need to change ever so slightly. Our understanding can never be complete. 

Using the field model described in section 1, detection probabilities are to be computed for each grid point to find the breach probability. The optimal decision rule that maximizes the detection probability subject to a maximum allowable false alarm rate a is given by the Neyman-Pearson formulation [20]. Two hypotheses that represent the presence and absence of a target are set up. The Neyman-Pearson (NP) detector computes the likelihood ratio of the respective probability density functions, and compares it against a threshold which is designed such that a specified false alarm constraint is satisfied. 

The breach probability P is quite sensitive to the false alarm rate a. As shown in Fig. 3b, as a increases, the SWSN allows more false alarms, and consequently, the NP detection probability and the detection probability pv of the targets at grid point v both increase in a. Consequently, the breach probability decreases. 

The model and results developed herein give clues that link false alarms to energy efficiency. Enforcing a low false alarm rate to avoid unnecessary response costs implies either a larger data-set (L) and hence a greater battery consumption, or a denser sensor network, which increases the deployment cost. Similar qualitative and/or quantitative inferences about the relationships between various other parameters can also be made. 

The general objective of all radar detection procedures is to get a constant false alarm rate (CFAR) due to the fact that the test cell almost always contains clutter and noise and only in a very few cases contains radar target echo signals. The statistical model and general detection procedure, in which the detector is fixed only with regard to the noise and clutter statistic and independently to the target statistic, has been developed by Neyman and Pearson. 

If CAGO-CFAR is applied in such typical clutter situations the false alarm rate is reduced at the clutter edges but the detection rate is simultaneously reduced slightly, see Figure 13. 

This method separates the window cells into a leading and a lagging part. Before the mean values of these parts are averaged, they are weighted by the factors a and (3. Optimum values for a and /3 are calculated in accordance with the level of interference of present targets, so that a constant false alarm rate and a high detection probability can be guaranteed. 

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