No description available.

<p>This licentiate thesis comprises two complementary studiesdealing with the sheet-fed offset printing of paper. The firststudy addresses the further development of a practical methodto acoustically monitor and analyse the film splitting ofoffset inks. This method was tested on laboratory printingequipment, specifically monitoring the continuous ink splittingin the nip of an IGT ink distribution unit and the short-timeink splitting in the inked print disc-paper nip of the printingunit of an ISIT instrument. The study verified that the inksplitting component of the acoustic signal contributes to thehigher frequency range (10-20 kHz) of the audible spectrum, andcan thus be separated from the lower frequency machine noise.Furthermore, the film splitting component is sensitive tochanges in the ink and printing conditions, thus enabling itsuse in probing the fundamental mechanisms occurring during inktransfer and also suggesting its applicability fornon-intrusive monitoring of industrial printing presses. Anincrease in film thickness during ink distribution correspondsto an increased acoustic power, with the exception of very lowink amounts, which give reduced acoustic emission due to alubricating effect. The effect of the presence of fountainsolution was simulated by adding emulsion-forming, butnon-evaporative, ethylene glycol. This produces an increase inacoustic power at low amounts, due to resistance to glycol dropdeformation, followed by a decrease at higher amounts owing toexcess glycol lining the rolls. During test printing on paper,increasing ink amounts also display an increased acousticresponse.</p><p>The second study further developed a theoretical model toexplain and predict the evolution of ink tack in terms of inksetting directly after offset printing on coated paper. Asmeasured by the ISIT, the tack of the printed ink rises duringshorter time periods, attains a maximum, and then falls atlonger times. The proposed model described how the ink tack,characterised by the impulse during disc pull-off, dependsdynamically on the viscoelastic properties of the ink, thecontact with paper and disc, and the flow geometry. The inksetting was modelled as a diffusion-limited transport of theoil vehicle through the ink film and into the pores of thecoated paper. The coupling of the tack and setting models,compared to the ISIT experimental measurements, then provided adiffusion coeffcient for ink setting during the tack riseperiod. This coeffcient decreases with time, and increasinglyrapidly with decreasing ink amounts due to theconcentration-dependent diffusion. For an accurate descriptionthe elasticity and adhesion effects also have to be considered,at least for explaining the tack fall period.</p>

Thesis (M.S.)--Rochester Institute of Technology, 1989. / Includes bibliographical references.

This licentiate thesis comprises two complementary studiesdealing with the sheet-fed offset printing of paper. The firststudy addresses the further development of a practical methodto acoustically monitor and analyse the film splitting ofoffset inks. This method was tested on laboratory printingequipment, specifically monitoring the continuous ink splittingin the nip of an IGT ink distribution unit and the short-timeink splitting in the inked print disc-paper nip of the printingunit of an ISIT instrument. The study verified that the inksplitting component of the acoustic signal contributes to thehigher frequency range (10-20 kHz) of the audible spectrum, andcan thus be separated from the lower frequency machine noise.Furthermore, the film splitting component is sensitive tochanges in the ink and printing conditions, thus enabling itsuse in probing the fundamental mechanisms occurring during inktransfer and also suggesting its applicability fornon-intrusive monitoring of industrial printing presses. Anincrease in film thickness during ink distribution correspondsto an increased acoustic power, with the exception of very lowink amounts, which give reduced acoustic emission due to alubricating effect. The effect of the presence of fountainsolution was simulated by adding emulsion-forming, butnon-evaporative, ethylene glycol. This produces an increase inacoustic power at low amounts, due to resistance to glycol dropdeformation, followed by a decrease at higher amounts owing toexcess glycol lining the rolls. During test printing on paper,increasing ink amounts also display an increased acousticresponse. The second study further developed a theoretical model toexplain and predict the evolution of ink tack in terms of inksetting directly after offset printing on coated paper. Asmeasured by the ISIT, the tack of the printed ink rises duringshorter time periods, attains a maximum, and then falls atlonger times. The proposed model described how the ink tack,characterised by the impulse during disc pull-off, dependsdynamically on the viscoelastic properties of the ink, thecontact with paper and disc, and the flow geometry. The inksetting was modelled as a diffusion-limited transport of theoil vehicle through the ink film and into the pores of thecoated paper. The coupling of the tack and setting models,compared to the ISIT experimental measurements, then provided adiffusion coeffcient for ink setting during the tack riseperiod. This coeffcient decreases with time, and increasinglyrapidly with decreasing ink amounts due to theconcentration-dependent diffusion. For an accurate descriptionthe elasticity and adhesion effects also have to be considered,at least for explaining the tack fall period.

Analzying questioned documents in a nondestructive nature has been an issue for the forensic science community. Using nondestructive techniques such as video spectral comparator does not give reliable information due to the variations in gray or color levels that are distinguished differently by analysts. Destructive techniques such as chromatography give dependable, qualitative and quantitative, information but involves altering the evidentiary value of these questioned documents. The paradox of document examination becomes a problem when document evidence is involved, especially when trying to preserve its evidentiary value and critical data is needed. Thus, a nondestructive technique has been developed to solve the loopholes in document examinations. Direct analyte-probed nanoextraction (DAPNe) is a nanomanipulation technique that extracts ink directly off the document for further examination. A watermark is left, at most, post-extraction. DAPNe utilizes a tip emitter, pre-filled with a solvent, which is controlled in x-, y-, and z-coordinates via joystick controller and aspirates/extracts using a pressure injector. The versatility of this technique lies within the solvent chemistry and its capability to be coupled to various types of instrumentation. The extraction solvent can be altered to target specific components in the ink. For example, a chelator may be added to target metal ions found in ancient inks or methanol may be added to target certain organic resins and binding agents found in modern inks. In this study, DAPNe has been coupled to nanospray ionization mass spectrometry, fluorescence microscopy, Raman spectroscopy, matrix-assisted laser desorption ionization mass spectrometry, and laser ablation to solve questioned document concerns in the area of falsified or forged documents, redacted documents, and aging studies.

No description available.

黃綺琪. / "2013年9月". / "2013 nian 9 yue". / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in Chinese and English. / Huang Qiqi.

No description available.

No description available.

Thesis (M.S.)--Rochester Institute of Technology, 1991. / Includes bibliographical references (leaves 132-134).