Progress in strain monitoring of tapestries

This paper reports interdisciplinary research between conservators and engineers designed to enhance the long-term conservation of tapestries (tapestry-weave hangings) on longterm display. The aim is to monitor, measure and document the strain experienced by different areas of a tapestry while it is hanging on display. Initial research has established that damage can be identified in the early stages of its inception, i.e., before it is visible to the naked eye. The paper also reports initial results of strain data visualisation that allows curators and conservators to examine how strain develops, thereby facilitating predictions about the changes in the form or condition of the tapestry. Strain data visualisation also allows the strain process to be recorded, thereby facilitating the effective documentation of display methods and conservation interventions. The paper reports the use of point measurements (using silica optical fibre sensors) and full-field monitoring (using 3-D photogrammetry with digital image correlation (DIC))

Long term condition monitoring of tapestries using image correlation

Digital Image Correlation (DIC) is used to extract non-contact full-field three-dimensional displacement and in-plane strains from an historic tapestries. A DIC-based approach is devised that allows the effect of RH variations on a tapestry to be quantified. A historical tapestry has been monitored in a closely controlled environment and in the natural environment. The results revealed that very small variations in RH can have significant effects on strain. An automated long term monitoring approach has been devised to allow strain data to be extracted in real time from tapestries in remote locations. The results show that DIC provides better understanding of the effect of RH fluctuations on strain which will ultimately lead to more insight into the degradation process of historical tapestries. The paper demonstrates the potential for using DIC as a condition monitoring tool

Strain monitoring of tapestries: results of a three-year research project

The outcomes of an interdisciplinary research project between conservators and engineers investigating the strain experienced by different areas of a tapestry are described. Two techniques were used: full-field monitoring using digital image correlation (DIC) and point measurements using optical fibre sensors. Results showed that it is possible to quantify the global strain across a discrete area of a tapestry using DIC; optical fibre and other sensors were used to validate the DIC. Strain maps created by the DIC depict areas of high and low strain and can be overlaid on images of the tapestry, creating a useful visual tool for conservators, custodians and the general public. DIC identifies areas of high strain not obvious to the naked eye. The equipment can be used in situ in a historic house. In addition the work demonstrated the close relationship between relative humidity and strain

Amyloid β oligomers constrict human capillaries in Alzheimer's disease via signaling to pericytes

Cerebral blood flow is reduced early in Alzheimer’s disease (AD). Because most of the vascular resistance within the brain is in capillaries, this could reflect dysfunction of contractile pericytes on capillary walls. Here we used live and rapidly-fixed biopsied human tissue to establish disease-relevance, and rodent experiments to define mechanism. We found that, in humans with cognitive decline, amyloid β (Aβ) constricts brain capillaries at pericyte locations. This was caused by Aβ generating reactive oxygen species, which evoked the release of endothelin-1 (ET) that activated pericyte ETA receptors. Capillary, but not arteriole, constriction also occurred in vivo in a mouse model of AD. Thus, inhibiting the capillary constriction caused by Aβ could potentially reduce energy lack and neurodegeneration in AD

Application of digital image correlation to deformation measurements in textiles

Digital image correlation (DIC) has proven to be an efficient technique for non-contact full-field strain measurement. Nevertheless, there have been no previous examples of using this technique to analyse strain in flexible textile fabrics. In this paper, a novel approach is developed based on DIC to monitor strain in textiles. The purpose of this paper is to demonstrate that DIC can be used to obtain full field strain maps from textile. The challenge is to use the weave of textile as the device for correlation. This can allow the technique to be applied to monitor strain in valuable textiles, such as historic tapestries

Application of digital image correlation to deformation measurements in textiles

Digital image correlation (DIC) has proven to be an efficient technique for non-contact full-field strain measurement. Nevertheless, there have been no previous examples of using this technique to analyse strain in flexible textile fabrics. In this paper, a novel approach is developed based on DIC to monitor strain in textiles. The purpose of this paper is to demonstrate that DIC can be used to obtain full field strain maps from textile. The challenge is to use the weave of textile as the device for correlation. This can allow the technique to be applied to monitor strain in valuable textiles, such as historic tapestries

Application of digital image correlation to deformation measurements in textiles

Digital image correlation (DIC) has proven to be an efficient technique for non-contact full-field strain measurement. Nevertheless, there have been no previous examples of using this technique to analyse strain in flexible textile fabrics. In this paper, a novel approach is developed based on DIC to monitor strain in textiles. The purpose of this paper is to demonstrate that DIC can be used to obtain full field strain maps from textile. The challenge is to use the weave of textile as the device for correlation. This can allow the technique to be applied to monitor strain in valuable textiles, such as historic tapestries

Long term condition monitoring of tapestries using image correlation

Digital Image Correlation (DIC) is used to extract non-contact full-field three-dimensional displacement and in-plane strains from an historic tapestries. A DIC-based approach is devised that allows the effect of RH variations on a tapestry to be quantified. A historical tapestry has been monitored in a closely controlled environment and in the natural environment. The results revealed that very small variations in RH can have significant effects on strain. An automated long term monitoring approach has been devised to allow strain data to be extracted in real time from tapestries in remote locations. The results show that DIC provides better understanding of the effect of RH fluctuations on strain which will ultimately lead to more insight into the degradation process of historical tapestries. The paper demonstrates the potential for using DIC as a condition monitoring too