Simulation of Fretting Wear in Halfplane Geometries: Part 1—The Solution for Long Term Wear

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
D. A. Hills ◽  
A. Sackfield ◽  
R. J. H. Paynter
Keyword(s):  
Pressure Distribution ◽  
Oscillatory Shear ◽  
Fretting Wear ◽  
Hertzian Contact ◽  
Final Configuration ◽  
State Of Stress ◽  
Long Time

The final configuration of a cylindrical Hertzian contact, subject to oscillatory shear and undergoing wear, is studied. It is assumed that wear has proceeded for a long time, so that the final, modified contact is wholly adhered. It is shown that the extent of the final contact corresponds to that of the initial adhered region and the pressure distribution, and state of stress at the new contact edge are all derived, so that the environment in which cracks nucleate is well described.

Enhancing the power generation of Rhodopseudomonas palustris-based MFC

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1261-1268
Author(s):  
Shu Otani ◽  
Dang-Trang Nguyen ◽  
Kozo Taguchi
Keyword(s):  
Activated Carbon ◽  
Rhodopseudomonas Palustris ◽  
Ozone Treatment ◽  
Maximum Power Density ◽  
On Demand ◽  
Long Time ◽  
Dry Conditions ◽  
Carbon Sheet ◽  
Uv Ozone

In this study, a portable and disposable paper-based microbial fuel cell (MFC) was fabricated. The MFC was powered by Rhodopseudomonas palustris bacteria (R. palustris). An activated carbon sheet-based anode pre-loaded organic matter (starch) and R. palustris was used. By using starch in the anode, R. palustris-loaded on the anode could be preserved for a long time in dry conditions. The MFC could generate electricity on-demand activated by adding water to the anode. The activated carbon sheet anode was treated by UV-ozone treatment to remove impurities and to improve its hydrophilicity before being loaded with R. palustris. The developed MFC could generate the maximum power density of 0.9 μW/cm2 and could be preserved for long-term usage with little performance degradation (10% after four weeks).

Charlemagne’s Health in ‘Old Age’: Did It Affect Carolingian Military Strategy?

Mediaevistik ◽  
2020 ◽  
Vol 32 (1) ◽  
pp. 11-53
Author(s):  
Bernard S. Bachrach
Keyword(s):  
Old Age ◽  
The Political ◽  
Military Strategy ◽  
The West ◽  
Long Time

During the first thirty-three years of his reign as king of the Franks, i.e., prior to his coronation as emperor on Christmas day 800, Charlemagne, scholars generally agree, pursued a successful long-term offensive and expansionist strategy. This strategy was aimed at conquering large swaths of erstwhile imperial territory in the west and bringing under Carolingian rule a wide variety of peoples, who either themselves or their regional predecessors previously had not been subject to Frankish regnum.1 For a very long time, scholars took the position that Charlemagne continued to pursue this expansionist strategy throughout the imperial years, i.e., from his coronation on Christmas Day 800 until his final illness in later January 814. For example, Louis Halphen observed: “comme empereur, Charles poursuit, sans plus, l’oeuvre entamée avant l’an 800.”2 F. L. Ganshof, who also wrote several studies treating Charlemagne’s army, was in lock step with Halphen and observed: “As emperor, Charlemagne pursued the political and military course he had been following before 25 December 800.”3

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

The Many Faces of Socioeconomic Change

2017 ◽  
Author(s):  
John Toye
Keyword(s):  
Socioeconomic Development ◽  
Adam Smith ◽  
First Century ◽  
Social Progress ◽  
Long Time ◽  
The Face ◽  
Scientific Expertise ◽  
The Many ◽  
Century Development

This book provides a survey of different ways in which economic sociocultural and political aspects of human progress have been studied since the time of Adam Smith. Inevitably, over such a long time span, it has been necessary to concentrate on highlighting the most significant contributions, rather than attempting an exhaustive treatment. The aim has been to bring into focus an outline of the main long-term changes in the way that socioeconomic development has been envisaged. The argument presented is that the idea of socioeconomic development emerged with the creation of grand evolutionary sequences of social progress that were the products of Enlightenment and mid-Victorian thinkers. By the middle of the twentieth century, when interest in the accelerating development gave the topic a new impetus, its scope narrowed to a set of economically based strategies. After 1960, however, faith in such strategies began to wane, in the face of indifferent results and general faltering of confidence in economists’ boasts of scientific expertise. In the twenty-first century, development research is being pursued using a research method that generates disconnected results. As a result, it seems unlikely that any grand narrative will be created in the future and that neo-liberalism will be the last of this particular kind of socioeconomic theory.

scholarly journals Acceptance of a Symptom-Based Approach for COVID-19 rtRT-PCR Testing to Conserve Resources in a Lower Middle-Income Setting

2021 ◽  
Vol 12 ◽  
pp. 215013272098771
Author(s):  
S. M. Rashed Ul Islam ◽  
Tahmina Akther ◽  
Md. Abdullah Omar Nasif ◽  
Sharmin Sultana ◽  
Saif Ullah Munshi
Keyword(s):  
Primary Method ◽  
Chain Reaction ◽  
Middle Income ◽  
Clinical Recovery ◽  
Clinical Presentations ◽  
Long Time ◽  
Nasopharyngeal Secretion ◽  
Polymerase Chain ◽  
Set Up

SARS-CoV-2 initially emerged in Wuhan, China in late 2019. It has since been recognized as a pandemic and has led to great social and economic disruption globally. The Reverse Transcriptase Real-Time Polymerase Chain Reaction (rtRT-PCR) has become the primary method for COVID-19 testing worldwide. The method requires a specialized laboratory set up. Long-term persistence of SARS-CoV-2 RNA in nasopharyngeal secretion after full clinical recovery of the patient is regularly observed nowadays. This forces the patients to spend a longer period in isolation and test repeatedly to obtain evidence of viral clearance. Repeated COVID-19 testing in asymptomatic or mildly symptomatic cases often leads to extra workload for laboratories that are already struggling with a high specimen turnover. Here, we present 5 purposively selected cases with different patterns of clinical presentations in which nasopharyngeal shedding of SARS-CoV-2 RNA was observed in patients for a long time. From these case studies, we emphasized the adoption of a symptom-based approach for discontinuing transmission-based precautions over a test-based strategy to reduce the time spent by asymptomatic and mildly symptomatic COVID-19 patients in isolation. A symptom-based approach will also help reduce laboratory burden for COVID-19 testing as well as conserve valuable resources and supplies utilized for rtRT-PCR testing in an emerging lower-middle-income setting. Most importantly, it will also make room for critically ill COVID-19 patients to visit or avail COVID-19 testing at their convenience.

Mean Sea Level as a Reference for Geodetic Leveling

1974 ◽  
Vol 28 (5) ◽  
pp. 524-530 ◽  
Author(s):  
G. W. Lennon
Keyword(s):  
Sea Level ◽  
World Ocean ◽  
Equipotential Surface ◽  
Scientific Discipline ◽  
Mean Sea Level ◽  
Sea Levels ◽  
Coastal Sea ◽  
Long Time ◽  
Marine System

The use of mean sea level as a surface of reference that might provide an independent control for geodetic leveling has been a long term goal arising from the classical analogy between the geoid as an equipotential surface and the surface assumed by a hypothetical undisturbed world ocean. The problems associated with this aim are now known to be vast, and are associated with the dynamics of the marine system, notably its response to meteorological forces, to variations in density and to the effects of basic circulation patterns. In consequence the mean sea level surface varies rapidly in both time and space. This identifies in fact a distinctive scientific discipline, coastal geodesy, in which contributions are required by both geodesists and oceanographers. It has come to be recognized that the coastal zone is a hazardous environment for all observational techniques concerned. On the one hand, the difficulties of measurement of coastal sea levels have only recently been understood; on the other hand, precise leveling procedures are now known to be influenced by the attraction of marine tides and by crustal deformation of tidal loading. Much of the data available for study are therefore inadequate and, moreover, it should be noted that long-time series are required. It is now possible to lay plans for both geodetic and oceanographic procedures to remedy these deficiencies in the long-term interests of the study.

Heads-up 3D eye surgery: Safety outcomes and technological review after 2 years of day-to-day use

2021 ◽  
pp. 112067212110128
Author(s):  
Claudia Del Turco ◽  
Giuseppe D’Amico Ricci ◽  
Marco Dal Vecchio ◽  
Caterina Bogetto ◽  
Edoardo Panico ◽  
...  
Keyword(s):  
Cataract Surgery ◽  
Case Series ◽  
Depth Of Field ◽  
Procedural Complication ◽  
Long Time ◽  
Procedural Complications ◽  
Resolution Imaging ◽  
Visualization Systems ◽  
3D Surgery

Background: 3D heads-up visualization systems are aimed to improve the surgical experience by providing high-resolution imaging. Objective of our study is to analyze, over a long-time span, the grade of satisfaction and safety of day-to-day 3D surgery compared to standard surgery and to investigate the technical distinctiveness between the heads-up systems currently in use. Methods: In this retrospective observational case series. we reviewed all surgical records of our ophthalmology-dedicated operatory rooms since the arrival of 3D heads-up viewing system, in November 2017. In particular, we compared the procedural complications of 3D-equipped operatory room (3DR) with the standard microscope operatory room (2DR). Moreover, a satisfaction questionnaire was administered to those surgeons shifting on both rooms to test their preferences on seven specific parameters (comfort, visibility, image quality, depth perception, simplicity of use, maneuverability and teaching potential). Results: 5483 eye surgeries were considered. 2777 (50.6%) were performed in 3DR and 2706 (49.3%) in 2DR. Procedural complication rate was comparable in 3DR and 2DR, also when considering different subtypes of surgery. Twelve surgeons (100% of our surgery team) participated in our satisfaction survey, expressing highest satisfaction score for 3D when applied in retina surgery. For cataract surgery, 3D scored best in all the parameters except for facility in use and depth of field perception. Conclusion: Long-term day-to-day use of 3D heads-up visualization systems showed its safety and its outstanding teaching potential in all ophthalmic surgical subtypes, with higher surgeons confidence for retina and cataract surgery.

The Study on Preventing Users Electic Larceny

2014 ◽  
Vol 602-605 ◽  
pp. 2939-2942
Author(s):  
Ying Ying Yang ◽  
Yi Shan ◽  
Zhi Tong Liu ◽  
Jian Feng Li ◽  
Jing Jin ◽  
...  
Keyword(s):  
Electric Power ◽  
Power Supply ◽  
Economic Loss ◽  
The Road ◽  
Energy Meter ◽  
Power Means ◽  
Long Time

For a long time,users electic larceny has been a headache topic of the electric power department.The users long-term electic larceny has brought great economic loss to the power supply department.In recent years,the stealing power means are emerging in an endless stream,and they have been broght mant difficulties to prevent electic larceny.But the road is high one feet evil spirite is high one a unit of lengh, according to the study on electic energy meter,we will understand the electic larceny means at the sours.Therefore, further study of stealing power means is also our current priority,only the better anti-stealing electic power means, can be completely blocked leak.

Dynamics of Interstitial Fluid Pressure in Extracellular Matrix Hydrogels in Microfluidic Devices

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Joe Tien ◽  
Le Li ◽  
Ozgur Ozsun ◽  
Kamil L. Ekinci
Keyword(s):  
Extracellular Matrix ◽  
Pressure Distribution ◽  
Interstitial Fluid ◽  
Scaling Laws ◽  
Fluid Pressure ◽  
Interstitial Fluid Pressure ◽  
External Loading ◽  
Interstitial Pressure ◽  
Time Resolved ◽  
Long Time

In order to understand how interstitial fluid pressure and flow affect cell behavior, many studies use microfluidic approaches to apply externally controlled pressures to the boundary of a cell-containing gel. It is generally assumed that the resulting interstitial pressure distribution quickly reaches a steady-state, but this assumption has not been rigorously tested. Here, we demonstrate experimentally and computationally that the interstitial fluid pressure within an extracellular matrix gel in a microfluidic device can, in some cases, react with a long time delay to external loading. Remarkably, the source of this delay is the slight (∼100 nm in the cases examined here) distension of the walls of the device under pressure. Finite-element models show that the dynamics of interstitial pressure can be described as an instantaneous jump, followed by axial and transverse diffusion, until the steady pressure distribution is reached. The dynamics follow scaling laws that enable estimation of a gel's poroelastic constants from time-resolved measurements of interstitial fluid pressure.

Integrity Assessment of a Free-Fall Lifeboat Launched From a FPSO

2015 ◽  
Author(s):  
Guomin Ji ◽  
Nabila Berchiche ◽  
Sébastien Fouques ◽  
Thomas Sauder ◽  
Svein-Arne Reinholdtsen
Keyword(s):  
Finite Element ◽  
Pressure Distribution ◽  
Structural Integrity ◽  
Dynamic Effect ◽  
Sensitivity Study ◽  
Computational Time ◽  
Load Factor ◽  
Time Varying ◽  
Integrity Assessment

The paper addresses the structural integrity assessment of lifeboat launched from floating production, storage and offloading (FPSO) vessels. The study is based on long-term drop lifeboat simulations accounting for more than 50 years of hindcast data of metocean conditions and corresponding FPSO motions. Selection of the load cases and strength analyses with high computational time is a challenge. The load cases analyzed are those corresponding to the 99th percentile of long term distribution of indicators for large slamming loads (CARXZ) or large submergence (Imaxsub). For six selected cases, the time-varying pressure distribution on the lifeboat hull during and after water impact is calculated by CFD simulations using StarCCM+. The finite element model (FEM) of the composite structure of the lifeboat is modelled by ABAQUS. Quasi-static finite element (FE) analyses are performed for the selected load cases. The structural integrity is assessed by the maximum stress and Tsai-Wu failure measure. In the present study, the load and resistance factors are combined and applied to the response. A sensitivity study is performed to investigate the non-linear load/response effects when the load factor is applied to the load. In addition, dynamic analysis is performed with the time-varying pressure distribution for selected case and the dynamic effect is investigated.

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