Two-particle correlations in azimuthal angle and pseudorapidity in inelastic p + p interactions at the CERN Super Proton Synchrotron

Results on two-particle ΔηΔϕ correlations in inelastic p + p interactions at 20, 31, 40, 80, and 158 GeV/c are presented. The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The data show structures which can be attributed mainly to effects of resonance decays, momentum conservation, and quantum statistics. The results are compared with the Epos and UrQMD models.ISSN:1434-6044ISSN:1434-605

Increase of Accuracy of Definition of Temperature by Sensors of Fire Alarms in Real Conditions of Fire on Objects

The theoretical analysis of the generalised circuit of the thermal sensor has shown that it is a converter of information of the resistive sensitive element into the corresponding voltage, which is carried out by the bridge measuring circuit. The dynamic model of the generalised circuit of the thermal sensor of fire alarm is presented in the form of the differential equations in the state space for the thermoresistive sensitive element in the form of a thin plate is developed on the basis of the generalised circuit of the thermal sensor. The private model of the thermal sensor of the first approximation in the state space is received for values Bi≤1. The given model allows researching the dynamic accuracy of the thermal sensor in various conditions of the fire alarm use taking into account the casual ambient temperature indignations. The influence of parameters of the bridge circuit and also of the sensitive element of the thermal sensor on dynamic accuracy in various conditions is investigated on the basis of this model. The analysis of dependence of the value of the second initial moment of an error on the considered characteristic parameters of the thermal sensor in dynamic conditions in the presence of casual temperature indignations of various intensity has shown that there are minimum values of the second initial moment of an error. Generally the minimum values of the second initial moment of an error depend on the characteristic parameters of the thermal sensor, current time and temperature conditions in the environment, characterised by the fire centre. There are possibilities of maintenance of invariance in time of the second initial moment of an error. The dependences of the optimum value of the characteristic parameter B1,1opt of the thermal sensor on speed of temperature increase caused by the fire centre, and also the intensity of masking casual temperature indignations on the object are received for this case.The received results allow to predict the expected accuracy for existing thermal sensors in various conditions of use, and also to develop optimum thermal sensors of single fire alarms for the guaranteed detection of low-power fire for real objects' protection

Development of a Method to Improve the Performance Speed of Maximal Fire Detectors

We conducted a theoretical analysis of the known method for improving performance speed of a maximal thermal fire detector under the action of temperature perturbation in the environment during fire in the interval of defining the temperature. It is demonstrated that the main shortcoming of this method is that the improvement in performance of a fire detector under complicated conditions is achieved by reducing the time constant of a detector. This leads to the growth in fluctuations of the output signal, reduces accuracy in determining the temperature and increases the number of false triggering in such detectors.Theoretical substantiation of the proposed method to improve performance speed of MTFD is based on the dynamic correction of output signal from a thermal sensor in fire detector by the inertial-forced link with a transfer function whose inertial part's time constant is changed by time in the interval of temperature measurement. We proposed a rule for changing the time constant.A comparative analysis of the known and the proposed methods revealed that the new method provides for an increase in performance speed of a fire detector without increasing the fluctuations in the output signal. Increasing the speed of action relative to the mathematical expectation and dispersion of fluctuations in the output signal is achieved at different moments of time, which are much less than the time of actuation of the maximal thermal detector – 20 s. The method proposed allows us to increase performance speed of a fire detector relative to the mathematical expectation of the output signal larger than by 5 times, and relative to the dispersion of fluctuations in the output signal – by 1.5 times.The method we devised is recommended to improve the performance speed of maximal thermal fire detectors under complicated conditions for operation, specific to industrial enterprises of metallurgy and petrochemical sector, for the purpose of their efficient fire protection

Investigation Into Acid­basic Equilibrium on the Surface of Oxides with Various Chemical Nature

The acid-base equilibrium on the surface of CaO, MgO, FeO, Al2O3, Fe2O3, SiO2, TiO2 oxides was studied. As a result of the study, the main provisions have been formulated which made it possible to propose models of surface active centers and schemes of their acid-base equilibrium. The acid-base and energy equilibrium parameters of the active centers in the deprotonation reactions were calculated. Regularities of changes in the acid-base and energy parameters of the active centers were determined depending on the nature of the central element of the crystal lattice, the number of OH-groups and the number of hydration. Acidity of all considered types of active centers depends to a large extent on the nature of the central element, namely its charge and coordination number. It was found that with increase in the coordination number of the central elements with the same charge, pKa of anhydrous centers and the value of their Gibbs free energy in deprotonation reactions increase. Acidity of isolated anhydrous centers increases in a direct proportion as the number of OH groups increases. The obtained regularity preserves for the surfaces of all oxides considered. It was shown for all oxides that when the amount of adsorbed water molecules increases, acidity of the active centers of all types increases and this dependence is identical to the growth of acidity with an increase in the number of OH groups. This indicates identity of the nature of acidity growth with an increase in thickness of hydroxyl and hydration surface layers. The obtained results will ensure prediction of oxide filler behavior in compositions and adjustment of operating properties of composite material

Examining the Learning Fire Detectors Under Real Conditions of Application

Theoretical analysis revealed that in order to create learning fire detectors, capable of adjusting to unknown conditions of application, it is expedient to consider the criterion of equality of probabilities of false detection and skipping a fire as a criterion of guaranteed fire detection. By using such detection criterion, it is possible to provide guaranteed fire detection under conditions of the absence of a priori information about statistics of the recorded data. The algorithms and structural circuits of the learning fire detectors were developed for the case of discrete and continuous data recording by sensors. Their distinguishing feature is the possibility of application under indeterminate conditions when there is no a priori information about the type of distribution laws of the recorded data, as well as their capability to adapt to previously unknown and changing application conditions and to provide guaranteed fire detection in this case. It was shown that the main limitation in the implementation of such algorithms is the need to use additional instructions from a trainer about the existence or the absence of a fire on the object. To overcome this limitation, it is proposed to apply the hypothesis about sufficient rarity of events related to a fire on the protected sites. This made it possible to use the registered information about the absence of fire as the instructions from a trainer. In this case, the resulting modified algorithm and the structural circuit of the proposed fire detector that matches it do not require instructions from a trainer and, in this sense, a detector becomes a self-learning fire detector.Results of examining the fire detectors, performed based on the example of real dynamics of the mean temperature of medium when alcohol is ignited and burned, demonstrated their high efficiency. In comparison with fire detectors that comply with the requirements of standard EN 54-5:2003, the examined self-learning fire detectors possess an essential gain in time (exceeding 170 times) of the guaranteed fire detection on the site under uncertain conditions. The ability of self-learning fire detectors to adapt to previously unknown conditions allows their application under non-stationary conditions in order to detect complex fires

Research Into Dynamics of Setting the Threshold and a Probability of Ignition Detection by Self­adjusting Fire Detectors

A general analysis of self-adjustment algorithm of fire detectors for early guaranteed ignition detection was carried out. It was shown that step magnitude in the algorithm of self-adjustment of fire detectors can be a fixed or a selected variable, depending on the level of registered actual data about the factor of ignition of combustible material. Specific features of fire detectors, self-adjusting by ignition, relate to a non-linear nature of the algorithm and conditions for providing guaranteed ignition detection. In this case, for effective self-adjustment of fire detectors, it is expedient to set the initial threshold value by registered actual data in the absence of ignition and to regulate the adaptation step size in a special way. It was shown that the fact of an increase in self-adjusted threshold relative to its original value can be a sign of ignition detection. For probabilistic assessment of the fact of ignition detection, it was proposed to use exponential smoothing of characteristic function, which allows generation of dynamic assessment of probability of ignition detection.A study of dynamics of self-adjusting threshold and probability of ignition detection indicate capability of self-adjusting fire detectors to provide early guaranteed detection of different sources of ignition of flammable materials under conditions unknown in advanc