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In cases where it is not practical to assume that the web growth is linear across the paper, a nonlinear web growth profile can be created to capture the actual displacements from the base separation.
This web growth profile example uses the same displacement measurements as in Table 1: Displacements from the yellow separation across a grid. It uses plate tower 1 for the black separation, plate tower 2 for the cyan separation, and plate tower 3 for the magenta separation. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE profile SYSTEM "WebGrowthProfile.dtd"> <profile> <measurePosition x = "1" y = "1" unit = "mm"/> <measureShift x = "1" y = "1" unit = "mm"/> <plate tower="1" side="U"> <xshift x= "-886.8" dx= "-1.38" /> <xshift x= "584.0" dx= ".82" /> <xshift x= "252.0" dx= ".36" /> <xshift x= "-12.7" dx= ".10" /> <xshift x= "12.7" dx= ".13" /> <xshift x= "315.5" dx= ".64" /> <xshift x= "584.0" dx= ".95" /> <xshift x= "886.8" dx= "1.40" /> </plate> <plate tower="2" side="U"> <xshift x= "-886.8" dx= "-1.04" /> <xshift x= "584.0" dx= ".66" /> <xshift x= "252.0" dx= ".36" /> <xshift x= "-12.7" dx= ".10" /> <xshift x= "12.7" dx= ".10" /> <xshift x= "315.5" dx= ".30" /> <xshift x= "584.0" dx= ".46" /> <xshift x= "886.8" dx= ".78" /> </plate> <plate tower="3" side="U"> <xshift x= "886.8" dx= ".52" /> <xshift x= "584.0" dx= ".30" /> <xshift x= "252.0" dx= ".08" /> <xshift x= "-12.7" dx= ".10" /> <xshift x= "12.7" dx= ".08" /> <xshift x= "315.5" dx= ".12" /> <xshift x= "584.0" dx= ".23" /> <xshift x= "886.8" dx= ".40" /> </plate> </profile> Note that the xshift element has two attributes: x, which is the horizontal distance across the web; and dx, which is the displacement from the base separation. The profile also specifies how the measurements are spaced along the plate with the measurePosition element, and the measureShift element specifies the units used for the displacement measurements themselves.
In this example, measurements are made across the drum (on the x axis), and around the drum (on the y axis). Across the drum, measurements are made every 8 inches and displacements are measured in 1-millimeter increments: < measurePosition x = "8" unit = "inch" /> <measureShift x = "1" unit = "mm" /> The x origin (the across-the-drum measurement) is at the centre of the plate, and so the left-hand x coordinates are negative, and the right-hand coordinates are positive. If the plate is 44" wide, and the first measurement is 2" in from the left edge, this left-most x coordinate will be (44/2 - 2) / 8 = -2.5. Because the measurements are spaced by measurePosition, they will have the x coordinates -2.5, -1.5, -0.5, 0.5, 1.5, and 2.5. The displacement, dx, is simply the measured difference between a feature position in the base separation and the "current" separation. The y origin (the around-the-drum measurement) is at the plate's leading edge, and so the y coordinates start from 0 and are always positive, but otherwise, the concept is the same as the across–the-drum measurements. The yshift element has two attributes, y and dy, which specify the y offset and the displacement in the y direction respectively. An example web growth profile with nonlinear web growth in both the x and y directions is shown below: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE profile SYSTEM "WebGrowthProfile.dtd"> <profile> <measurePosition x = "8" y = "2" unit = "inch" /> <measureShift x = "1" y = "1" unit = "mm" /> <plate tower="1" side="U"> <xshift x= "-2.5" dx= "-1.584" /> <xshift x= "1.5" dx= ".720" /> <xshift x= "-.5" dx= "-1.544" /> <xshift x= ".5" dx= ".288" /> <xshift x= "1.5" dx= "1.288" /> <xshift x= "2.5" dx= "1.578" /> <yshift y= ".5" dy= "-3.288" /> <yshift y= "1.5" dy= "0" /> <yshift y= "2.5" dy= "-2.578" /> <yshift y= "3.5" dy= "-4" /> <yshift y= "4.5" dy= "-2" /> <yshift y= "5.5" dy= "0" /> <yshift y= "6.5" dy= "-2" /> <yshift y= "7.5" dy= "0" /> </plate> </profile> |
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Lorsqu'il n'est pas réaliste de supposer un étirement linéaire de la bande à travers le papier, un profil d'étirement de la bande non linéaire peut être créé pour capturer le déplacement réel par rapport à la sélection de base.
Cet exemple de profil d'étirement de la bande utilise les mêmes mesures de déplacement que dans le tableau 1 : déplacements par rapport à la sélection jaune sur une grille. Il utilise le modèle tour 1 pour la sélection noire, le modèle tour 2 pour la sélection cyan et le modèle tour 3 pour la sélection magenta. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE profile SYSTEM "WebGrowthProfile.dtd"> <profile> <measurePosition x = "1" y = "1" unit = "mm"/> <measureShift x = "1" y = "1" unit = "mm"/> <plate tower="1" side="U"> <xshift x= "-886.8" dx= "-1.38" /> <xshift x= "584.0" dx= ".82" /> <xshift x= "252.0" dx= ".36" /> <xshift x= "-12.7" dx= ".10" /> <xshift x= "12.7" dx= ".13" /> <xshift x= "315.5" dx= ".64" /> <xshift x= "584.0" dx= ".95" /> <xshift x= "886.8" dx= "1.40" /> </plate> <plate tower="2" side="U"> <xshift x= "-886.8" dx= "-1.04" /> <xshift x= "584.0" dx= ".66" /> <xshift x= "252.0" dx= ".36" /> <xshift x= "-12.7" dx= ".10" /> <xshift x= "12.7" dx= ".10" /> <xshift x= "315.5" dx= ".30" /> <xshift x= "584.0" dx= ".46" /> <xshift x= "886.8" dx= ".78" /> </plate> <plate tower="3" side="U"> <xshift x= "886.8" dx= ".52" /> <xshift x= "584.0" dx= ".30" /> <xshift x= "252.0" dx= ".08" /> <xshift x= "-12.7" dx= ".10" /> <xshift x= "12.7" dx= ".08" /> <xshift x= "315.5" dx= ".12" /> <xshift x= "584.0" dx= ".23" /> <xshift x= "886.8" dx= ".40" /> </plate> </profile> Remarquez que l'élément xshift comporte deux attributs : x, qui mesure la distance horizontale à travers la bande et dx, qui représente le déplacement par rapport à la sélection de base. Ce profil spécifie également l'espacement des mesures le long de la plaque avec l'élément measurePosition, tandis que l'élément measureShift détermine les unités utilisées pour les mesures de déplacement proprement dites.
Dans cet exemple, les mesures sont réalisées à travers le tambour (sur l'axe x) et autour du tambour (sur l'axe y). À travers le tambour, les mesures sont réalisées tous les 8 pouces (203 mm) et le déplacement est mesuré par incréments de 1 mm : < measurePosition x = "8" unit = "inch" /> <measureShift x = "1" unit = "mm" /> L'origine x (mesure à travers le tambour) étant au centre de la plaque, les coordonnées x de gauche sont négatives et les coordonnées de droite positives. Si la plaque mesure 44 pouces (112 mm) de large et que la première mesure est de 2 pouces (50 mm) à compter du bord gauche, la coordonnée x la plus à gauche sera (44/2 - 2) / 8 = -2,5. Les mesures étant espacées par l'élément measurePosition, les coordonnées x sont les suivantes -2,5, -1,5, -0,5, 0,5, 1,5 et 2,5. Le décalage, dx, correspond simplement à la différence mesurée entre un emplacement particulier de la sélection de base et la sélection "actuelle". L'origine y (mesure autour du tambour) étant sur le bord avant de la plaque, les coordonnées y commencent à 0 et sont systématiquement positives ; mis à part ce point, le concept est identique à celui utilisé pour les mesures à travers le tambour. L'élément yshift comporte deux attributs, y et dy, qui spécifient respectivement le décalage y et le déplacement en direction y. Un exemple de profil d'étirement de la bande non linéaire en directions x et y est illustré ci-dessous : <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE profile SYSTEM "WebGrowthProfile.dtd"> <profile> <measurePosition x = "8" y = "2" unit = "inch" /> <measureShift x = "1" y = "1" unit = "mm" /> <plate tower="1" side="U"> <xshift x= "-2.5" dx= "-1.584" /> <xshift x= "1.5" dx= ".720" /> <xshift x= "-.5" dx= "-1.544" /> <xshift x= ".5" dx= ".288" /> <xshift x= "1.5" dx= "1.288" /> <xshift x= "2.5" dx= "1.578" /> <yshift y= ".5" dy= "-3.288" /> <yshift y= "1.5" dy= "0" /> <yshift y= "2.5" dy= "-2.578" /> <yshift y= "3.5" dy= "-4" /> <yshift y= "4.5" dy= "-2" /> <yshift y= "5.5" dy= "0" /> <yshift y= "6.5" dy= "-2" /> <yshift y= "7.5" dy= "0" /> </plate> </profile> |