Hydraulic feedback

Nuclear power reactors inherently have some highly nonlinear characteristics, which means that whatever objective function (there are several possibilities) and constraints are used to define and quantify acceptable LPs, some of these system variables will inevitably be nonlinear functions of the problem s control (decision) variables. Examples of such nonlinearities include the effects of local thermal and hydraulic feedback and the time dependence that results from radiation exposure (an accumulated history effect). Particularly with respect to the latter, the computational expense associated with analyzing a single LP solution can be substantial. When considered within the context of of tens of thousands of solutions, as is often required for the use of modem optimization routines, the CPU run time cost becomes prohibitively expensive. 

Cyclic loads were applied to the specimens using a hydraulic feedback load system which could be either load-, stroke-, or strain-controlled. Sinusoidal and linear-ramp waveforms were generally used. Fatigue frequencies were varied from 0.1 to 15 Hz. Unless otherwise stated, mechanical property data were obtained at a fatigue frequency of 10 Hz. 

Due to the constraints in the neutronic calculation models used for the core design, the fuel assemblies are axially divided into a number of fuel elements, and within each fuel element, the fuel assembly is homogenized. For the purposes of evaluating the thermal-hydraulic feedback to the neutronic calculations and evaluating the basic thermal-hydraulic characteristics of the core, detailed calculations involving the modeling of each fuel rod are not necessary. There are three fundamental thermal-hydraulic parameters required for the core design calculations ... 

Since the coolant flow velocity and hence core pressure drop decrease, the time delay is longer and flow feedback is larger, destabilizing the reactor (hydraulic feedback). 

The net effect on the stabihty depends on the balance between the above two effects. In the present analysis, the neutronic feedback effect is found to be dominant over the hydraulic feedback effect. Here, the core power and flow rate are kept constant and the decay ratios are calculated with various feedwater temperatures. The decay ratio is found to decrease when the core inlet temperature decreases as shown in Fig. 5.61. 

Fig. 4.42 Hydraulic servomechanism with walking beam feedback linkage.

The use of hydraulic systems for the setting, operation and control of machine tools has increased significantly. Hydraulic mechanisms being inter-linked with electronic controls and/or feedback control systems. In machine tools, hydraulic systems have the advantage of providing stepless and vibration-less transfer of power. They are particularly suitable for the linear movement of tables and slideways, to which a hydraulic piston may be directly coupled. 

The pump consists of dual reciprocating pistons which are hydraulically controlled. Oil is distributed by the system to the two pistons which are 180° out of phase (as with the Altex and Waters systems). A fixed volume of hydraulic fluid is delivered to the control system for every revolution of a special gear pump. The latter is controlled by a motor having a constant speed and a tachometer feedback circuit. Other compensating circuits... 

To use the true stress or strain, it is necessary to measure the cross section or the length of the sample continuously and to have a closed-loop feedback on a (hydraulic) setup. Therefore, most of the time, only cyclic loads or displacements are applied onto the sample. 

The design, optimization, and control of the EMR for the decolorization of Orange II require the implementation of a control system. Two control systems were developed (a) a feedforward system based on the knowledge of kinetics and reactor hydraulics and (b) a feedback system based on the concentration of DO into the reactor, which was observed to be a main variable that provides extensive information about the development of the process. 

NEM of equation (2) for perturbations in the coupling coefficients of the nonlinear NEM strategy [7]. For the treatment of local thermal and hydraulic and fission product feedbacks, an additional second order accurate, nonlinear correction is applied in the evaluation of equation (3). This correction is obtained by direct substitution of the uncorrected power density response of equation (3) into analytical sensitivities for the change in cross-section with locd power [14]. 

Oil applications are based on pressure atomization technology even if small power application solutions are available based on oil evaporation by heat. Electronic control of the fuel/air ratio previews an actuator to move a butterfly for controlling the air flow and an actuator to move the oil pressure regulator. For gas, two actuators control two butterflies, one for gas and one for air, even if fhe gas pneumatic valves (whose working principle is based on a pneumatic feedback) are widely used. More advanced burners control air flow changing the fan speed, reducing the pressure drop in the hydraulic pipes and valves. Despite this, a butterfly valve is often necessary to control startup operation, especially for high power applications. 

The main processes involved in the geotechnical and geo-environmental engineering may be classified as thermal (T), hydraulic (H), mechanical (M), and chemical (C ). In a geo-engineering system these processes are related to each other through interaction. The properties and parameters in one process may be affected by the others. Mutual feedbacks of the influences then lead to a combined process of development, the so called coupled processes. However, in a geo-engineering system not all the processes involved may be equally important in controlling the total system behavior. In many cases the particularity of the studied problems has to be taken into account. 

The plugs have caused no problems during initial 2 or 3 years of operation. On the basis of the feedback from BN350 and taking into account the experience gained at the BN600 reactor from the monitoring of the protective liquid and hydraulic seal eutectic the former was decided to be periodically replaced and cleaned to remove mechanical impurities. 

LMRs with oxide-fueled core Models modified and newly developed mto the code so far mclude models for reactivity feedback effects and pool thermal-hydraulics In order to venfy the logic of the models developed, and to assess the effectiveness of the inherent safety features based upon the negative reactivity feedbacks m achieving the safety design objectives of passive safety, a preliminary analysis of UTOP and ULOF/LOHS performance has been attempted... 

In path-driven machines the drive system defines the path of the ram, while the forces are defined by the feedback from the forming process. Typical realization of such machines is the mechanically driven presses. Force-driven machines define by their drive system the force at every position of the ram, while the path is defined by the feedback from the forming process. Typical realizations of such machines are hydraulic presses, where the pressure and the cross section of the piston define the press force. Both machines suffer from energetic limitations of their drive system, which influences accelerations and thus speed. If only the energy for the process is defined by the machine, the machine is classified as energy-driven press machine. Typical realizations are hammers and flywheel spindle presses. 

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