Three-sensor System Research Articles

«Электронный язык» на основе модифицированных полиариленфталидами электродов для распознавания модельных растворов триптофана

The effect of auxiliary substances in the composition of the dosage form (sucrose, lactose, talc and starch) on the voltammetric registration of tryptophan using two- and threesensor systems such as "electronic tongue" based on glassy carbon electrodes modified with polyarylenephthalides was studied. For the subsequent chemometric processing of the obtained data, the principal component analysis and soft independent modeling of class analogies were used. It has been shown that electrodes modified with various polyarylenephthalides have cross-sensitivity to four model solutions of tryptophan, each of which contains a certain auxiliary component. When the modified electrodes are used separately, the analyzed model solutions of tryptophan form clusters on the score plots of PCA that intersect with each other, which does not allow them to be reliably recognized. However, the combination of modified electrodes into two- and three-sensor systems due to cross-sensitivity makes it possible to obtain the PCA score plots, in which clusters of samples of model solutions of tryptophan intersect less or do not intersect at all, and, therefore, to recognize them with a high probability. In almost all cases of using two- and three-sensor systems, the classification sensitivity is 100%. When using modified electrodes separately, the specificity of the classification varies from 20 to 100%, when using two-sensor systems – from 50 to 100%. The specificity of the classification when using a three-sensor system is not less than 90%. The proposed sensor system, after additional studies, can be used to recognize medicines containing the same active substance, but different auxiliary components, and will also allow detecting the presence of impurities in medicines.

Can Trichromacy equal Tetrachromacy?

Although our distant ancestors once had the same visual sensor arrangement as extant birds and reptiles, colour vision in most mammals is very limited; essentially reduced to a single dimension of information produced by a pair of colour sensors, each with a fairly broad spectral response. Humans belong to a small subset of mammals that have re-developed some of the ability that was lost by their distant ancestors. They have done this by stretching the natural variation of the light absorbing pigments in one of the visual sensors, thereby adapting it toward a third colour sensor. It is generally assumed that due to the differences and limitations of this solution that colour perception in humans is fundamentally different to that of our distant relations; animals which have been able to continually extend and refine their colour vision over a period of more than two hundred million years. However, over that extended period of time the fundamentals of their colour vision have remained largely unchanged; a system of four visual sensors, each with a specific colour filter that systematically narrows the spectral response. In this paper we demonstrate that a three-sensor system with a broad spectral response (similar in spectral profile to that of the human colour sensors) can in certain conditions be equivalent to a four-sensor system (broadly similar to bird and reptile colour sensors). This suggests that human colour perception (sometimes referred to as a 'trichromatic' system) may be broadly equivalent to colour perception found in a variety of other animals such as birds or reptiles (whose colour vision is generally referred to as 'tetrachromatic'). The difference between a sensor system that uses four spectrally narrow colour sensors arranged into two opponent pairs and a three-sensor system is that the former relies on a simple difference measurement whereas the later requires the use of complex trigonometric functions - which are at least two orders of magnitude greater in computational complexity.

Locating fish bomb blasts in real-time using a networked acoustic system

Results are presented of a demonstration of real-time fish blast location in Sabah, Malaysia using a networked hydroacoustic array based on the ShotSpotter gunshot location system. A total of six acoustic sensors - some fixed and others mobile - were deployed at ranges from 1 to 9 km to detect signals from controlled test blasts. This allowed the blast locations to be determined to within 60 m accuracy, and for the calculated locations to be displayed on a map on designated internet-connected computers within 10 s. A smaller three-sensor system was then installed near Semporna in Eastern Sabah that determined the locations of uncontrolled blasts set off by local fishermen. The success of these demonstrations shows that existing technology can be used to protect reefs and permit more effective management of blast fishing activity through improved detection and enforcement measures and enhanced community engagement.

Multipoint Chemical Gas Sensing Using Frequency-Shifted Interferometry

We apply frequency-shifted interferometry to interrogate multiple gas sensors along a single fiber. This method uses a tunable continuous-wave laser and a slow detector, and allows spectral overlap of sensors. It can be used to quantify the concentrations of single or different gas species at multiple locations. A three-sensor system was used to demonstrate this capability, achieving a minimum detectable acetylene concentration of 230 ppm with a 3-cm gas cell, or equivalently, 6.9 ppmmiddot m. The design considerations in the implementation and the system parameters are also discussed.

Risk-based reconfiguration of safety monitoring system using dynamic Bayesian network

To prevent an abnormal event from leading to an accident, the role of its safety monitoring system is very important. The safety monitoring system detects symptoms of an abnormal event to mitigate its effect at its early stage. As the operation time passes by, the sensor reliability decreases, which implies that the decision criteria of the safety monitoring system should be modified depending on the sensor reliability as well as the system reliability. This paper presents a framework for the decision criteria (or diagnosis logic) of the safety monitoring system. The logic can be dynamically modified based on sensor output data monitored at regular intervals to minimize the expected loss caused by two types of safety monitoring system failure events: failed-dangerous (FD) and failed-safe (FS). The former corresponds to no response under an abnormal system condition, while the latter implies a spurious activation under a normal system condition. Dynamic Bayesian network theory can be applied to modeling the entire system behavior composed of the system and its safety monitoring system. Using the estimated state probabilities, the optimal decision criterion is given to obtain the optimal diagnosis logic. An illustrative example of a three-sensor system shows the merits and characteristics of the proposed method, where the reasonable interpretation of sensor data can be obtained.

An efficient algorithm for optimal linear estimation fusion in distributed multisensor systems

Under the assumption of independent observation noises across sensors, Bar-Shalom and Campo proposed a distributed fusion formula for two-sensor systems, whose main calculation is the inverse of submatrices of the error covariance of two local estimates instead of the inverse of the error covariance itself. However, the corresponding simple estimation fusion formula is absent in a general distributed multisensor system. In this paper, an efficient iterative algorithm for distributed multisensor estimation fusion without any restrictive assumption on the noise covariance (i.e., the assumption of independent observation noises across sensors and the two-sensor system, and the direct computation of the Moore-Penrose generalized inverse of the joint error covariance of local estimates are not necessary) is presented. At each iteration, only the inverse or generalized inverse of a matrix having the same dimension as the error covariance of a single-sensor estimate is required. In fact, the proposed algorithm is a generalization of Bar-Shalom and Campo's fusion formula and reduces the computational complexity significantly since the number of iterative steps is less than the number of sensors. An example of a three-sensor system shows how to implement the specific iterative steps and reduce the computational complexities

System of four distance sensors for high-accuracy measurement of topography

A novel sensor system consisting of four distance sensors is proposed for the scanning measurement of topography. The system achieves high accuracy and allows high lateral resolution. The configuration of the system can be chosen such that it guarantees perfect reconstruction of the topography in the presence of offset and pitch errors of the scan system provided the sensor measurements are error-free. Moreover, a favorable propagation of the random and systematic errors of the sensor measurements is achieved. The error influences are investigated and the sensor system is compared to a previously proposed three-sensor system by analyzing simulated data.

Variability in soil heat flux from a mesquite dune site

For many natural and agricultural landscapes, vegetation partially covers the ground surface, resulting in significant variations in soil heat flux between interspace areas and underneath vegetation. This is particularly apparent in arid and semiarid regions where vegetation cover is low and clustered or ‘clumped’ with large areas of exposed soil. Surface heterogeneity presents significant challenges to the use of standard micro-meteorological measurement techniques for estimating surface energy balance components. The objective of this study was to use an array of 20 soil heat flux plates and soil temperature sensors to characterize the spatial and temporal variability in soil heat flux as affected by vegetation and micro-topographic effects of mesquite dunes in the Jornada Experimental Range in southern New Mexico. Maximum differences in soil heat flux among sensors were nearly 300 W m −2. Maximum differences among individual sensors under similar cover conditions (i.e. no cover or interdune, partial or open canopy cover and full canopy cover) were significant, reaching values of 200–250 W m −2. The ‘area-average’ soil heat flux from the array was compared with an estimate using three sensors from a nearby micro-meteorological station. These sensors were positioned to obtain soil heat flux estimates representative of the three main cover conditions: namely, no cover or interdune, partial or open canopy cover, and full canopy cover. Comparisons between the array-average soil heat flux and the three-sensor system indicate that maximum differences on the order of 50 to nearly 100 W m −2 are obtained in the early morning and mid-afternoon periods, respectively. These discrepancies are caused by shading from the vegetation and micro-topography. The array-derived soil heat flux also produced a significantly higher temporal varying soil heat flux/net radiation ratio than what has been observed in other studies under more uniform cover conditions. Results from this study suggest that, to determine the number and location of sensors needed for estimating area-average soil heat flux in this type of landscape, one needs to account not only for the clustering of the vegetation cover but also micro-topography.

A Boolean algebra approach to multiple sensor voting fusion

A technique for integrating multiple-sensor data using a voting fusion process that combines the individual sensor outputs is described. An important attribute of the method is the automatic confirmation of the target by the fusion processor without the need to explicitly determine which sensors and what level of sensor participation are involved. A three-sensor system, with multiple confidence levels in each sensor, is discussed to illustrate the approach. Boolean algebra is used to derive closed-form expressions for the multiple sensor-system detection probability and false-alarm probability. Procedures for relating confidence levels to detection and false alarm probabilities are described through an example. The hardware implementation for the sensor system fusion algorithm is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Wind Velocity and Convergence Measurements at the Boulder Atmospheric Observatory Using Path-Averaged Optical Wind Sensors

Abstract In a cooperative field study of the planetary boundary layer, three optical wind sensors were placed around a 300 m meteorological tower in a 450 m equilateral triangle 3–4 m above the terrain. It was found that the convergence measured by the three-sensor system correlates well with in situ measurements of vertical wind by anemometers located on the tower at heights up to 300 m during the occurrence of thermal plumes. By analyzing the correlation between the optically measured convergence and the vertical wind measurements made on the tower, the inversion layer, if below the top of the tower, can usually be located in the early morning when thermal plumes are active. The space-averaged horizontal wind vectors measured by the optical system have good, though not perfect, agreement with the tower measurements at the lowest layer (10 m above the ground), and with the measurements of a nearby network of surface anemometers. A comparison of the optically measured convergence with the direction of the...