Cooling towers are used as a final heat sink which cools the reactor auxiliary systems and transfers the heat energy to the atmosphere. The reliability endowed upon the cooling tower operation in a nuclear power plant is considerably high when compared to other power plants since the proper functioning of auxiliary systems is crucial for the decay heat removal from the core. Hence, appropriate chemistry control is mandatory in the operation of cooling towers for corrosion control, scale prevention, and control of biological growth. The operating data and water chemistry parameters like conductivity, turbidity, free residual chlorine, pH, cycles of concentration, chlorides, hardness, and alkalinity are analyzed for a typical nuclear power plant. The effect of the individual water quality parameter is correlated by the Pearson matrix to find its influence on the system water chemistry parameter. It is observed that the build-up of chloride ions in the cooling water is the major contributing factor for the cooling tower feed and bleed operations. The aspect of reducing the feed and bleed operation is analyzed, and suitable modifications are suggested to reduce water consumption.

Single-phase thyristor full converter and semi been made in the present paper and all the possible modes of converter fed dc drives with phase angle control scheme have operation and the sub-cases therein have been identified and been analysed under all possible modes of operation of continuous the corresponding expressions for the various performance and discontinuous armature current conduction. For each case, factors derived for both thyristor full converter and semi expressions for the various performance quantities have been v presented comprehensively. All the cases have been simulated converter. using power system block set tool box in MATLAB and the III. MODES OF OPERATION simulation results are found to be same as those obtained from the derived expressions. Results obtained on a 220 V, 5 hp separatelyIn the analysis of these converters, we have duty interval(s) excited dc motor operating under all modes of operation, were in which the ac source is connected to the load through a set of also in agreement with simulated / calculated values. thyristors. Depending on the armature circuit inductance, armature current and speed setting there may be a zero current I. NOMENCLATURE interval also. In addition, in the semi converter there could be a free-wheeling interval in which load current flows only E motor back emf, V through the devices and the source current is zero. Based on io : instantaneous armature current ( load current ), A these, the various modes identified are classified in Table 1. is : instantaneous ac supply current, A fundamental component of rms ac supply current, A I : rms ac supply current, A In any mode of operation, considering one-half cycle i.e., Kb back emf constant, volts/rad/sec starting from the instant of firing of one set of devices to the La motor armature circuit inductance, H instant of firing of the other set of devices, the input and output Ra motor armature circuit resistance, Q voltage and current equations of the converter circuits are: Vm maximum value of the ac supply voltage, V VS : instantaneous ac supply voltage, V Duty interval (is = io) vO : instantaneous converter dc output voltage, V VO = vs = Vm Sin o)t (1) V0 average converter dc output voltage, V Raio +La(dio/dt)+E Vs (2) Z motor impedance, Q oc : firing angle, deg Free-wheeling interval (is = 0): P : extinction angle, deg vO= 0 (3) O instant at which the instantaneous supply voltage is Ra io + La (dio / dt) + E = 0 (4) equal to the motor back emf, deg X : angle at which conduction starts, deg Zero current interval (is = = 0) 0) :rotor speed in rad/sec vO = E (5)

Web applications are the most universal way to make services and data accessible on the Internet. With the increase in the use of these applications, there has also been an increase in the amount and complexity of vulnerabilities and attacks. These attacks target directly the back-end database systems of the web application to achieve information. In this paper, a Dual Safeguard Intrusion Detection and Prevention System was proposed to models the user network behaviors and create normality models of isolated user sessions across both frontend and back-end of the application. To accomplish this, a Lightweight virtualization technique is used to allocate each user's web session to a dedicated container, providing an isolated virtual computing environment. An Intrusion Detection Model for web applications based on Hidden Markov Model was also proposed.

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