Role Of Pits Research Articles

‘Sae lofty and wide’

Archaeological investigations undertaken by Headland Archaeology (UK) Ltd as part of the Clyde Wind Farm and Clyde Wind Farm Extension construction project produced a body of evidence that tells the story of human occupation and settlement in the Upper Clyde Valley. The investigations conducted between 2007 and 2015 included evaluations, site excavations, and the monitoring of groundworks across four distinct landscapes: Clyde Valley North (Woodend), Camps Valley, Midlock Valley, and Clyde Valley South (Newton Plantation). The results of this work, together with those from specialist studies and scientific analyses, have allowed for a range of key research questions to be addressed. These include an exploration of prehistoric upland activities, the role of pits and special places, and the development of settlement patterns and structures. Evidence for mobile Mesolithic and Neolithic communities was identified across the landscape with indications of the repeated visitation of specific locations. The role of pits in the creation of special places was particularly evident across Camps and Midlock Valleys. In the 2nd millennium bc, the hillsides were transformed by the creation of platform settlements. Enclosed settlements and hillforts appeared along the banks of the Clyde Valley in the 1st millennium bc marking a distinct shift in the role of landscape in expressing status and identity. In addition to prehistoric remains, limited evidence of early historic metalworking and medieval rural settlement was uncovered. Across all landscapes and periods, the themes of transition and transformation came to the fore, painting an increasingly dynamic picture of life in the Upper Clyde Valley. The scale and complexity of the archaeological works also allowed for a review of current methodologies, including the role of an Archaeological Clerk of Works, with implications for future strategies.

The Limited Role of Pit Formed by Microjet in Evolution of Cavitation Erosion in the Incubation Period

AbstractStepwise cavitation erosion is used to study pits formed by microjets. The aim is to determine the role of the pit in the development of cavitation erosion damage, including geometrical features of the pitted area and pit counting. The study also identified the dominant feature in the development of cavitation damage. We used a vibratory cavitation apparatus to perform cavitation erosion damage on a stainless steel, SUS 304, in tap water with scanning electron microscopy (SEM) at 5-min intervals from t = 0 min to t = 45 min. We then analyzed and characterized the pits formed by impacting the surface with a microjet. These results showed that individual pits and clusters of pits are characterized by a black spot surrounded by plastic deformation, and both are irregular in shape. This suggests that the microjet is hitting the wear surface in an oblique direction. Over the course of the test time, neither the shape nor the size of the microjet pits and their clusters change; pit diameters approximately 2 μm or less. The area of pits and their clusters does not exceed 1% of the worn surface. All these features demonstrate that the pit and its clusters do not impact the evolution of cavitation damage. Our results also indicated that slip bands were caused by a shock wave. Slip bands are large (>10 μm) and account for about 30% of the wear surface. This confirms that slip bands are predominantly responsible for the development of cavitation; the predominant cavitation mechanism is fatigue due to multiple shock waves.

PERSONAL INCOME TAX: EXPERIENCE OF FOREIGN COUNTRIES

Introduction. In the current conditions of the integration movement of Ukraine to the European Union and the reform of the institutions of state power, the issue of studying foreign experience of the system of taxation of individuals' incomes is actualized. The application of effective practices of other states will contribute to increasing the fiscal role of the personal income tax in Ukraine, reducing social inequality and increasing the welfare of the population. Purpose. The purpose of the article is to find out the features, trends and problems of the functioning of the personal income tax in foreign countries. Results. The article deals with the foreign experience of functioning of the system of personal income taxation. The role and role of PIT in the EU and OECD countries is shown. The proportional and progressive approach to taxation of this tax is considered, their key advantages and disadvantages are determined. An analogy has been made between the European states, the OECD member states and Ukraine. The objective necessity of establishing a non-taxable minimum or partial exemption of citizens' incomes from taxes in the context of support of low-income categories of the population and ensuring social justice is substantiated. Conclusions. It is concluded that in developed countries, the progressive system of taxation of the PIT along with the minimum non-taxable minimum is an effective tool for generating budget revenues and solving social inequalities in society. Instead, third-world states can not use this mechanism in a qualitative way due to significant tax compliance problems. They apply a proportional taxation system for PIT that minimizes tax evasion and international competitiveness.

Comparative Evaluation of the Marginal Sealing Ability of Fuji VII® and Concise® as Pit and Fissure Sealants

The anatomical pits and fissures of the teeth have long been recognized as susceptible areas for the initiation of dental caries. The extreme vulnerability to decay of these pits and fissures on the occlusal surfaces has prompted dental scientists to seek methods of caries prevention. Motivated by the role of pit and fissure sealants in caries prevention, the aim of this study was to compare the efficacy of Fuji VII glass ionomer sealant and Concise resin-based sealant. An in vitro study was undertaken using forty premolars extracted for orthodontic reasons. The teeth were divided into two groups and sealants were applied. One was an experimental group using Fuji VII as a pit and fissure sealant and the other a control group using Concise. The teeth were kept in gentian violet dye for 24 hours, the sectioned samples were observed for the extent of dye penetration, and scores were based on established scoring criteria. The comparison of the performance of the two groups showed a statistically significant difference. The Concise resin-based sealant performed better in terms of sealing ability than did the Fuji VII glass ionomer sealant.

Ion‐mediated increase in the hydraulic conductivity of Laurel stems: role of pits and consequences for the impact of cavitation on water transport

Changes in hydraulic conductivity (K(h)) were measured in stems of Laurus nobilis L. during perfusion with KCl, NaCl or sucrose solutions. Ionic solutes induced marked increase of K(h) with respect to deionized water but sucrose had no effect. The kinetics of KCl-induced K(h) increase was measured together with changes in [K(+)] of the perfused solution. K(h) increases were paralleled by increases in the [K(+)](out)/[K(+)](in) ratio. Samples of different lengths or with increasing percentage loss of conductivity (PLC) due to xylem cavitation were tested, with the aim of increasing radial flow through intervessel pits. KCl solutions enhanced the K(h) of 12-cm-long samples with a concentration-dependent effect up to 100 mm KCl. DeltaK(h) increased from 3 to 30% in 1.5- and 12-cm-long samples, respectively and remained constant for longer samples. Increasing PLC induced an exponential increase in DeltaK(h). PLC measured with KCl solutions was significantly less than that measured with deionized water, suggesting that measurements of PLC can be affected by the composition of the perfused solution. Experiments support the hypothesis that the 'ionic effect' is mediated by physico-chemical changes of pectins of the pit membranes and raise the possibility that plants might alter the ionic composition of the xylem sap to alleviate the hydraulic impact of cavitation.

Influence of pitting on the fatigue life of a turbine blade steel

ABSTRACTThe role of pits as stress raisers and their influence on fatigue life has been investigated for a 12Cr turbine blade material. A particular feature of this work was the establishment of an electrochemical procedure for generating pits with ‘controlled’ pit depth and low density.Pits grown under laboratory conditions were partially spherical in shape and simulated, in general appearance, those observed in service. In terms of the threshold stress intensity factor, the results supported the concept of pits acting as effective cracks of the same depth, provided that a short crack model based on an effective crack length is used.

Corrosion fatigue mechanisms of an 8090 AlLiCu alloy

The corrosion fatigue behaviour of a commercial 8090 AlLi alloy has been analysed in a 3.5% NaCl solution at pH 6. At applied low plastic strain amplitudes, the effect of strain rate ϵ dot is shown to be very significant on the fatigue lives and on the crack initiation modes. This effect is related to the different corrosion processes which can take place at free corrosion potential. The analysis of the crack initiation modes by scanning electron microscopy as a function of ϵ dot allows us to emphasize the role of pitting on the corrosion fatigue behaviour of the 8090 alloy. Complementary tests are performed to separate the role of pitting from the role of other electrochemical processes. According to the value of the strain rate, four different corrosion fatigue mechanisms are proposed. The role of pitting is shown to be very different according to the strain rate range. Finally an interaction between stress corrosion and corrosion fatigue is observed at very low strain rates and related to the crack initiation process.