Cross direction control

Cross directional control uses measured CD profiles to adjust actuators which are spaced across the machine width. The goal of CD controls is to ensure even quality in the CD. The challenges of CD control are  

Actuators at the headbox are used to control the CD basis weight profile. Two principles are widely used  

The advantage of dilution actuators is, that the headbox nozzle is not changed mechanically. Local changes in the headbox nozzle result in a nonuniform jet 

The uneven jet velocity also has negative side effects on other paper properties Hfce the fiber orientation profile. 

The dryness of the sheet entering the drying section should be as uniform as possible or the profile should have a certain shape. Deviations in CD dryness profiles before the dryer section result e. g. in uneven shrinkage, curl, overdried edges, edge cracks, paper web breaks or poor moisture profile at the reel. 

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AP Featherstone and RD Braatz. Model-based cross-directional control. Tappi J., 83(3) 203-207, 1999. 

While it is the manager s responsibility to direct, control, and maintain his or her part of the organization, it is the leader who expands, crosses boundaries, innovates, and brings about changes in how the organization operates. Since these are. . . states of mind, anyone, including formal managers, can choose to adopt a creative perspective at any time. 

Consider the net mass flow through the cylindrical differential element illustrated in Fig. 3.6. The following analysis makes no explicit reference to the scalar product of the flux vector and the outward normal, j ndA. Rather, it is based on a more direct observation of how mass diffuses into and out of the control volume. It is presumed that the spatial components of j are resolved into spatial components that are normal to the control-volume faces, jk,z, jk,r, and jk,e Further it is presumed that a positive value for a spatial component of jk means that the corresponding flux is in the direction of the positive coordinate. The components of the diffusive mass flux are presumed to be continuous and differentiable throughout the fluid. Therefore the flux components can be expanded in a first-order Taylor series to express the local variations in the flux. The net mass of species k that crosses the control surfaces diffusively is given by the incoming minus the outgoing mass transport. Consider, for example, transport in the radial direction ... 

Clearly, the heat flux is a vector whose direction is defined by the temperature gradient. The net heat dQ/dt (W or J/s) that crosses a control surface into the volume by thermal conduction is given by... 

The adenosine receptor-mediated modulation of synaptic transmission exceeds the direct control of neurotransmitter release, and the concept of adenosine as a modulator of modulators has been developed (Sebastiao and Ribeiro 2000), highlighting the potential of adenosine to fine-tune synaptic activity. Fine-tuning of transmitter release by adenosine may be exerted by (1) triggering responses to other modulators, (2) regulating the rate of desensitization of other receptors, (3) forming heterooligomers with other receptor types and/or (4) cross-talk of intracellular pathways they activate. 

In addition to the steric issues in chemoselectivity, which are intrinsic to the reaction of a given set of substrates, solvent and sensitizer effects are of importance for a direct control on selectivity because they can be controlled. The reaction of 8a and 13c catalyzed by sensitizer 6 shows an overall increase in cross-product formation with increasing solvent polarity. Entries 4 and 5 in Table 4.1 demonstrate that use of 3a reduces the formation of cross-products in polar solvents. This difference can be rationalized by the fact that after ET by 6, a strongly complexed ion pair is formed, whereas in the case of 3a, the sensitizer is neutral and can dissociate more easily from the radical cation formed. 

As briefly described above, the objective of the Sheet Forming Control Problem (SFCP) is to control the sheet thickness at 15 different points as uniformly as possible around different targets (yo). Thus, there are 15 controlled variables (CV s), which correspond to the thicknesses in the cross-direction, with the same relative weight (w). Moreover, this process has 9 manipulated variables (MV s) and 3 disturbance variables (DV s). The steady-state gain model, the sets within which the input and output variables are constrained and the relative weights of the output variables are given in the following equations ... 

The hydrodynamic transistors shown in Table 2 can be classified in two types distinguished by the function of the gel actuator. The actuator of type B acts as servo drive actuating the valve seat. The actuator of type B is directly placed within the flow channel. Therefore, the stimulant, which is typically a component of the process medium, directly controls the sensor-actuator element. The hydrogel swells or shrinks by absorption or release of the process medium and regulates the channel cross-section. Figure 1 shows two examples of such hydrodynamic transistors. 

Yu YL, Nakano M, Maeda T, Kondo M, Ikeda T. 2005. Precisely direction controllable bending of cross linked liquid crystalline pol5mer films by hght. Mol Cryst Liq Cryst 436 1235 1244. 

The machine direction of the loom is called the warp, and the cross-direction is the fill (also called woof or weft). The number of yams can be varied in both warp and fill to control the weight, thickness, appearance, and strength of the fabric. When each fill yam is laced alternately over and then under the warp, the type of fabric (called the weave) is known as plain weave. 

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