Analogue to Digital and Digital to Analogue Converters (ADCs and DACs): A Review Update

This is a review paper updated from that presented for CAS 2004. Essentially, since then, commercial components have continued to extend their performance boundaries but the basic building blocks and the techniques for choosing the best device and implementing it in a design have not changed. Analogue to digital and digital to analogue converters are crucial components in the continued drive to replace analogue circuitry with more controllable and less costly digital processing. This paper discusses the technologies available to perform in the likely measurement and control applications that arise within accelerators. It covers much of the terminology and 'specmanship' together with an application-oriented analysis of the realisable performance of the various types. Finally, some hints and warnings on system integration problems are given.Comment: 15 pages, contribution to the 2014 CAS - CERN Accelerator School: Power Converters, Baden, Switzerland, 7-14 May 201

Self-, other-, and joint monitoring using forward models

In the psychology of language, most accounts of self-monitoring assume that it is based on comprehension. Here we outline and develop the alternative account proposed by Pickering and Garrod (2013), in which speakers construct forward models of their upcoming utterances and compare them with the utterance as they produce them. We propose that speakers compute inverse models derived from the discrepancy (error) between the utterance and the predicted utterance and use that to modify their production command or (occasionally) begin anew. We then propose that comprehenders monitor other people’s speech by simulating their utterances using covert imitation and forward models, and then comparing those forward models with what they hear. They use the discrepancy to compute inverse models and modify their representation of the speaker’s production command, or realize that their representation is incorrect and may develop a new production command. We then discuss monitoring in dialogue, paying attention to sequential contributions, concurrent feedback, and the relationship between monitoring and alignment

Curing kinetics and effects of fibre surface treatment and curing parameters on the interfacial and tensile properties of hemp/epoxy composites

The curing kinetics of neat epoxy (NE) and hemp fibre/epoxy composites was studied and assessed using two dynamic models (the Kissinger and Flynn-Wall-Ozawa Models) and an isothermal model (the Autocatalytic Model) which was generally supported by the experimental data obtained from dynamic and isothermal differential scanning calorimetry (DSC) scans. The activation energies for the curing of composites exhibited lower values compared to curing of NE which is believed to be due to higher nucleophilic activity of the amine groups of the curing agent in the presence of fibres. The highest tensile strength, σ was obtained with composites produced with an epoxy to curing agent ratio of 1:1 and the highest Young's modulus, E was obtained with an epoxy to curing agent ratio of 1:1.2. Alkali treated hemp fibre/epoxy (ATFE) composites were found to have higher σ and E values compared to those for untreated hemp fibre/epoxy (UTFE) composites which was consistent with the trend for interfacial shear strength (IFSS) values. Composites σ and E were found to be higher for a processing temperature of 70°C than for 25°C for both UTFE and ATFE composites, but were found to decrease as the curing temperature was increased further to 120°C

ADCs to DACs (analog-to-digital and digital-to-analog converters)

ADCs and DACs are crucial components in the relentless drive to replace analog circuitry with more controllable and less costly digital processing. This paper reviews the technologies available for measurement and control as applied to accelerators. It covers much of the terminology and ‘specmanship’ together with an application-oriented analysis of the performance to be expected of the various types. Finally, some guidance on system integration problems is given

Influence of accelerated ageing on the physico-mechanical properties of alkali-treated industrial hemp fibre reinforced poly(lactic acid) (PLA) composites

30 wt% aligned untreated long hemp fibre/PLA (AUL) and aligned alkali treated long hemp fibre/PLA (AAL) composites were produced by film stacking and subjected to accelerated ageing. Accelerated ageing was carried out using UV irradiation and water spray at 50 °C for four different time intervals (250, 500, 750 and 1000 h). After accelerated ageing, tensile strength (TS), flexural strength, Young's modulus (YM), flexural modulus and mode I fracture toughness (KIc) were found to decrease and impact strength (IS) was found to increase for both AUL and AAL composites. AUL composites had greatest overall reduction in mechanical properties than that for AAL composites upon exposure to accelerated ageing environment. FTIR analysis and crystallinity contents of the accelerated aged composites support the results of the deterioration of mechanical properties upon exposure to accelerated ageing environment

An analysis of selected Indiana coals by the particle count method

Indiana Geological Survey Report of Progress 6The bituminous coals of Indiana show a characteristic bright and dull banding which is due to alternating bands of five distinct physical constituents, namely, vitrain, clarain, durain, fusain, and mineral matter. A petrographic analysis of Indiana Coals V, VI, and VII was made to determine whether any appreciable variation in the content of these ingredients occurred. The “particle count method” was used in analyzing the coals. In order to establish a standard for comparing Coals V, VI, and VII, an index number was determined for each sample by dividing the combined clarain-durain content by the vitrain content. These index numbers are the most reliable and satisfactory basis for the comparison of coals, and they maybe used to some extent in coal correlation. Because vitrain has the most desirable combustion properties, a coal that has a high vitrain content may be more desirable commercially. Coals VI and VII were found to have a distinctly higher vitrain content than Coal V. Localities of high-vitrain content within the various coal beds in Indiana are outlined in this report. Suggestions for further use of the particle count method in coal analysis are made.Indiana Department of Conservatio

Moving Forward not Back: The Rule of Law & Equitable Growth Save Democracy

This dissertation focuses on the relevant factors that influence people’s perceived levels of democracy in their country. Using World Values Survey Wave 6 (2010-2014) I demonstrate that an interactive-effect between individuals’ confidence in the courts and their beliefs about the possibility of equitable economic growth account for the greatest effect on their perceived levels of democracy

Quantitative Evaluation Of Myocardial Fibrosis Using Polarization-video Microscopy

Fibrosis is an essential feature of tissue repair and is characterized by the deposition of collagen. Fibrosis in the myocardium is prevalent among patients with heart disease and can significantly impair cardiac function. The evaluation and treatment of myocardial scarring is however limited by a lack of quantitative and practical methods for studying fibrosis. My thesis was that both the amount and the relative maturity of fibrotic collagen could be quantified directly from histologic sections by taking advantage of the birefringent properties of collagen and assessing these with computer-based image analysis. A system, using polarized light microscopy and video microscopy, was therefore developed.;To quantify fibrosis, the high brightness intensity of collagen stained with picrosirius red was exploited. Using color filtering and image processing, a digital video image of myocardium was generated in which only collagen was visible. The collagen was quantified as the area-fraction of visible pixels. This video approach was compared to that of hydroxyproline analysis using samples from 14 autopsy hearts. A strong correlation (r = 0.98) between the two techniques was demonstrated. Also, in 22 endomyocardial biopsy specimens, the collagen content determined by the video technique was shown to correlate well with the collagen content determined by stereology (r = 0.95).;To quantify the relative maturity of fibrosis, the increasing birefringence of maturing fibrotic collagen was utilized. The median grey-level of all pixels depicting collagen served as the index of collagen brightness and reflected fiber birefringence. I measured the brightness of collagen in the scar that formed after superficial injury to the rat gracilis muscle. In this model, the diffuse arrangement of the collagen fibers was similar to that in interstitial myocardial fibrosis. Collagen brightness increased progressively over a 63-day period. I also measured brightness in the scar that formed after myocardial infarction in dogs and found that collagen brightness in 6-week infarcts was greater than that in 3-week infarcts (p {dollar}\u3c{dollar} 0.01).;The clinical utility of the system was confirmed by two studies in which fibrosis in the human transplanted heart was studied. In the first study, I examined the relationship between the length of time the heart was not perfused during transport from donor to recipient (graft ischemic time), and the amount of fibrosis present one week after transplantation. Collagen content was measured in endomyocardial biopsy samples from 36 transplant recipients and found to be linearly related to graft ischemic time (r = 0.60). In the second study, I examined the relationship between allograft rejection and the amount and activity of fibrosis in five transplant patients. Serial biopsy samples, taken over a period of up to 1.5 years after transplantation, were evaluated. The collagen content of samples taken one year after surgery did not correlate with the frequency or severity of rejection. However, the activity of fibrosis was greatest in the early weeks ({dollar}\u3c{dollar}12) after transplantation which was time when most of the rejection episodes had occurred.;In conclusion, both the content and the activity of myocardial fibrosis can be quantified using the polarization-video microscopy technique