The role of freezing-thaw cycling in rock samples topography evolution and rock cliff retreat

2021 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun ◽  
...  
Keyword(s):  
Freezing Point ◽  
Meteorological Data ◽  
Test Chamber ◽  
Monitoring Program ◽  
Dynamic Environment ◽  
Rock Properties ◽  
Rock Surface ◽  
Physical Weathering ◽  
Rock Samples

<p>Freezing-thaw weathering is recognized as one of the most significant factors in the fatigue of rock mass in areas where the temperature periodically fluctuates around the freezing point. <br>A one-year monthly SfM monitoring program from December 19, 2019, to January 7, 2021, was done to detect rockfall activity on a rockslide cliff composed of marl-sandstone at La Cornalle, Switzerland. More than one hundred rockfall events were detected during this period with the volumes varied from 0.005m<sup>3</sup> to 4.85m<sup>3</sup>. <br>We texture all the rockfalls on the 3D SfM model. It is shown that most of them are mainly located in three areas:  the top of the cliff, the foot of the cliff, and the medium-left part of the cliff. The common feature of these three parts is that the layers are more or less overhanging with dense fractures around them. At the same time, the meteorological data collected by a weather station on site is correlated with the rockfall events to figure out the relationship between each other. Actually, about 30% of total rockfall volume fell during winter on this site. The triggering factor of rockfall during winter is related to freezing-thaw cycling. This kind of weathering can be understood as an interplay between rock properties and its dynamic environment.<br>In order to make clear the role of freezing-thaw played on the rockfall generation, an on-site 24h monitoring measurement program that consists of two crack meters, one rock thermal sensor, and thermal camera monitoring is installed in January 2021. Those datasets will help to understand how the crack grows with the changing temperature. In addition, freezing-thaw cycling laboratory experiments for the rock samples taken from different areas of the cliff will be done with an environmental test chamber. The topography of the rock samples before and after the experiments will be acquired by a 3D handheld scanner. This work will benefit to reveal the rock surface evolution during the freezing-thaw cycling in a dynamic environment with varied humidity and number of cycles. <br>In conclusion, the combination of on-site measurements and laboratory freezing-thaw experiments will provide a good basis for a better understanding of the rockfall triggering mechanism led by physical weathering.</p>

scholarly journals Strategic Planning and Competitive Advantage of ICT Small and Medium Enterprises in Kenya

2013 ◽  
Vol 1 (1) ◽  
pp. 191 ◽  
Author(s):  
Zachary B. Awino
Keyword(s):  
Strategic Planning ◽  
Competitive Advantage ◽  
Small And Medium Enterprises ◽  
Critical Role ◽  
Dynamic Environment ◽  
Business Environment ◽  
Positive Influence ◽  
Balanced Score Card ◽  
Medium Enterprises

The Paper is the research findings on the role of strategic planning and competitive advantage of ICT Small and Medium Enterprises in Kenya. Literature suggests that the contemporary business environment in which organisations operate is increasingly becoming uncertain and unpredictable. Significant changes are mostly driven by technological changes, globalisation and trade liberalisation. As a result, like large enterprises, SMEs are facing new and unexpected challenges that threaten their competitiveness. While most countries acknowledge the critical role that SMEs contribute to their economies, both as an engine of growth and sustainable development, many questions still remain unanswered as to the determination of the critical challenges facing SMEs and how these challenges could be addressed to improve their competitiveness. These challenges have increased the need for empirical information which is essential for decision making in addressing issues that are likely to enhance SMEs survival and growth. It is noted that there has been no adequate research studies on the role of strategic planning and competitive advantage of SMEs. This study contributes to the need to address the research gaps and thus explored the role of strategic planning and competitive advange of SMEs in Kenya. The study population consisted of 238 ICT SMEs from Nairobi and its environs. A sample size of 146 firms constituting 61 per cent of the total population was selected through stratified sampling. The study aimed to collect data from 438 respondents from top, middle and lower management teams. Structured questionnaires with closed and open ended questions was used for data collection, 239 responses were received from 123 ICT firms a response rate of 55 per cent and 84.2 per cent respectively. Key characteristics of strategic planning including formality, environmental analysis processes both internal and external orientations, strategies adopted, and implementation and control were recorded. Data analysis was done using descriptive statistics, factor analysis, t-test, ANOVA, correlation, correlation matrixes and regression analysis. The key findings revealed that strategic planning has significant and positive influence in performance of SME’s. The test of hypothesis revealed that strategic planning has positive and significant influence on competitive advantage. The study demonstrated strategic planning as a learning tool and a strategic resource which is consistent with the underlying assumptions of resource based theory, systems theory, chaos theory and balanced score card model assumptions. It is envisaged that, this kind of research is likely to generate useful discussions on the role of strategic planning and performance, of SMEs. It is apparent that entrepreneurs of SMEs cannot ignore strategic planning as significant changes in competitive advantage is the result of change or effective application of strategic planning. Policy makers and academicians may need to address the capacity needs of SMEs and develop strategic planning model that address the challenges that SMEs encounter in a dynamic environment.

scholarly journals The Changing Role of Marketing in the Third Millennium

2017 ◽  
Vol 7 (1) ◽  
pp. 39
Author(s):  
Reshma Sreedharan ◽  
Rehin KR
Keyword(s):  
Competitive Advantage ◽  
Dynamic Environment ◽  
New Techniques ◽  
The Third ◽  
Third Millennium ◽  
Changing Role ◽  
New Millennium

<div><p><em>In the 21<sup>st</sup> century, any marketer has to face stiff competition due to the dynamic environment. Nowadays, marketers are offering more value to the customers so that they can gain a competitive advantage. The present customers are now digitally conscious and are opposing the traditional way of marketing. The marketers have to identify the new techniques which can be used to target the new millennium customers and earn sizeable profits. This paper focuses on the emerging marketing trends and its repercussions.<strong></strong></em></p></div>

scholarly journals Adverse Weather Evokes Nostalgia

2018 ◽  
Vol 44 (7) ◽  
pp. 984-995 ◽  
Author(s):  
Wijnand A. P. van Tilburg ◽  
Constantine Sedikides ◽  
Tim Wildschut
Keyword(s):  
Cognitive Load ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Psychological Benefits ◽  
Adverse Weather

Four studies examined the link between adverse weather and the palliative role of nostalgia. We proposed and tested that (a) adverse weather evokes nostalgia (Hypothesis 1); (b) adverse weather causes distress, which predicts elevated nostalgia (Hypothesis 2); (c) preventing nostalgia exacerbates weather-induced distress (Hypothesis 3); and (d) weather-evoked nostalgia confers psychological benefits (Hypothesis 4). In Study 1, participants listened to recordings of wind, thunder, rain, and neutral sounds. Adverse weather evoked nostalgia. In Study 2, participants kept a 10-day diary recording weather conditions, distress, and nostalgia. We also obtained meteorological data. Adverse weather perceptions were positively correlated with distress, which predicted higher nostalgia. Also, adverse natural weather was associated with corresponding weather perceptions, which predicted elevated nostalgia. (Results were mixed for rain.) In Study 3, preventing nostalgia (via cognitive load) increased weather-evoked distress. In Study 4, weather-evoked nostalgia was positively associated with psychological benefits. The findings pioneer the relevance of nostalgia as source of comfort in adverse weather.

EFFECT OF AIR VELOCITY ON INHALATION DOSES DUE TO RADON AND THORON PROGENY IN A TEST CHAMBER

2020 ◽  
Vol 189 (3) ◽  
pp. 401-405
Author(s):  
Rosaline Mishra ◽  
Rama Prajith ◽  
Rajeswari Pradhan Rout ◽  
Jalaluddin Sriamirullah ◽  
Balwinder Kaur Sapra
Keyword(s):  
Physical Properties ◽  
Environmental Conditions ◽  
Test Chamber ◽  
Air Velocity ◽  
Attachment Rate ◽  
Inhalation Dose ◽  
Decay Products ◽  
Calibration Chamber ◽  
Thoron Progeny

Abstract Inhalation doses due to radon and thoron are predominantly due to the inhalation of progeny of Radon and Thoron. The progeny/decay-products of radon and thoron are particulates unlike their parent gas and exhibit different physical properties like attachment to the aerosols and deposition on different surfaces. All these properties in turn depend on the environmental conditions such as air velocity, aerosol concentration, attachment rate, etc. The role of air velocity on deposition on surfaces decides the progeny particles left in the air for inhalation. Therefore, in the present work, we have studied the effect of air velocity on the inhalation dose due to radon and thoron progeny at the centre of a 0.5-m3 calibration chamber as well as on all surfaces. Hence, the studies were carried out at different air velocities, and inhalation doses were measured using deposition-based direct radon and thoron progeny sensors.

THE MODERATING ROLE OF CREATIVITY IN THE RELATION BETWEEN COLLABORATION AND PERFORMANCE

2019 ◽  
Vol 24 (06) ◽  
pp. 2050051
Author(s):  
SERJE SCHMIDT ◽  
DUSAN SCHREIBER ◽  
CRISTIANO MAX PEREIRA PINHEIRO ◽  
MARIA CRISTINA BOHNENBERGER
Keyword(s):  
Dynamic Environment ◽  
Structural Equations ◽  
Creative Industries ◽  
Performance Factors ◽  
The Face ◽  
And Performance ◽  
Collaborative Efforts ◽  
Moderating Role ◽  
Collaboration Strategies

Within the dynamic environment of the recent creative industries, collaboration performs a central role. The literature has consistently explored the interaction between creative professionals with three types of actors: (1) the clients or public; (2) co-workers and; (3) business agents. The relative importance of each actor in the face of creative activities, however, remains theoretically fragmented and empirically under-researched. Therefore, this study aims to address the following question: what is the role of creativity in the relation between the type of partner to which the collaborative efforts are directed and the performance factors? To answer that question, a quantitative study comparing university students in more creative-intensive and less creative-intensive occupations was performed. An exploratory structural equations modelling (SEM) was developed for that purpose. Performance factors of both groups seem to follow similar priorities. Their collaborative efforts, however, show different patterns, supporting the conclusion that creativity is indeed related to different collaboration strategies. Although collaboration with co-workers seems to be developed similarly between more creative and less creative professionals, that with clients and business agents showed different results.

scholarly journals Integrator’s Coordination on Technological Innovation Performance in China: The Dual Moderating Role of Environmental Dynamism

2019 ◽  
Vol 12 (1) ◽  
pp. 308
Author(s):  
Lina Mao ◽  
Jinghua Li ◽  
Changwei Guo
Keyword(s):  
Technological Innovation ◽  
Dynamic Environment ◽  
Innovation Performance ◽  
Strategic Development ◽  
Trade Friction ◽  
Product Systems ◽  
Complex Product Systems ◽  
The Relationship ◽  
Moderating Role

As the backbone of national strategic development, Complex Product Systems (CoPS) have made great achievements in China, the world’s largest demand market and second largest economy. However, their further development is challenged by the dynamic environment, including the ongoing Sino-US trade friction, for example. The aim of this research is to investigate the influence of the dynamic external environment on CoPS innovation. Based on contingency theory, this study identifies and investigates the moderating effects of technological and market dynamism on the relationship between the integrator’s coordination and its technological innovation performance. Using survey data from 209 CoPS integrator enterprises in China, the findings show that (1) the positive effect of an integrator’s coordination on technological innovation performance is strengthened by technological dynamism, while (2) weakened by market dynamism. In addition, (3) the technological dynamism acts as a higher-order moderating role in inhibiting the negative moderating effect of market dynamism on the main effect in general. Furthermore, (4) an unexpected but inspiring finding shows that the integrator’s coordination facilitates innovation most when both the technology and market dimensions are highly dynamic. This study may indicate that managerial recognition may have significant influence on enterprise’s behavior.

On Succession in A Saxicolous Lichen Community

1985 ◽  
Vol 17 (2) ◽  
pp. 167-172 ◽  
Author(s):  
M. E. J. Woolhouse ◽  
R. Harmsen ◽  
L. Fahrig
Keyword(s):  
Community Diversity ◽  
Rock Surface ◽  
Surface Erosion ◽  
Physical Weathering ◽  
Rock Face ◽  
Lichen Community ◽  
Competition For Space ◽  
Allogenic Processes ◽  
Opening Up ◽  
Lichen Flora

AbstractThe lichen flora was sampled at each of the five sites on a near-vertical gneiss rock face. The sites were ranked according to the degree ofweathering of the rock surface and were taken to represent different stages in a succession. The succession shows an increase in species richness and diversity over time, although the proportion of the rock face unoccupied by lichens increases at the oldest site. The succession will be driven by allogenic processes, physical weathering of the rock, facilitation, especially the effects of lichens on surface erosion, and by inhibition, through competition for space. At the oldest site mortality of lichen thalli becomes important, continually opening up new areas for recolonization and maintaining community diversity. The succession may be described by four phases: (1) colonization, (2) growth,(3) competition and (4) senescence.

The Mechanics of Rock Failure Due to Water Jet Impingement

1974 ◽  
Vol 14 (01) ◽  
pp. 10-18 ◽  
Author(s):  
S.E. Forman ◽  
G.A. Secor
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Pressure Distribution ◽  
Pore Pressure ◽  
Static Pressure ◽  
Jet Impingement ◽  
Water Jet ◽  
Rock Properties ◽  
Rock Surface ◽  
Pressure Loading

Abstract The initiation of fracture in a rock mass subjected to the impingement of a continuous water jet has been studied. The jet is assumed to place a quasistatic pressure loading on the surface of the rock, which is treated as a saturated, porous-elastic, isotropic, and homogeneous half-space. While this pressure loading is held constant, the impinging water flows through the rock according to Darcy's law and pressurizes the fluid in the pores. The pore pressure distribution couples with the stress field due to the surface loading to produce an effective stress field, which can start tensile fracturing directly under the load. At various time intervals after initial impingement, the effective-stress field is computed using finite element methods and the results, together with the Griffith criterion for tensile failure, produce the loci of the zones of fracture initiation. The behavior of these zones is displayed as a function of the two jet parameters - pressure and nozzle diameter - and the five rock properties: Young's modulus, Poisson's ratio, tensile strength, porosity and permeability, and time. To experimentally verify that pore pressure plays an important role in the mechanism of rock fracture due to jet impingement, thin sheets of copper (0.001 to 0.005 in.) were placed between a continuous jet (up to 20,000 psi) and the surface of a block of Indiana limestone. The purpose of the copper sheet was to allow the pressure of the jet to be transmitted to the rock, but to prevent water from entering the pore structure. Using pressure substantially greater than the threshold pressure of pressure substantially greater than the threshold pressure of limestone (3,500 psi) where penetration always occurred in the absence of the copper sheet, placement of the sheet was sufficient to prevent any visible damage from occurring to the rock surface, provided the jet did not penetrate the copper first. provided the jet did not penetrate the copper first Introduction The method by which a water jet penetrates and fractures a rock mass is highly complicated and poorly understood. This is mainly because the rock is subjected during the impact to several separate processes, each of which can cause failure. Failure can result from the effects of dynamic stress waves, static pressure loading and erosion. The degree of failure caused by each mechanism is, of course, dependent on the rock properties and jet parameters. parameters. In the first few microseconds of impingement, a subsonic jet pressure on the rock surface reaches the so-called "water hammer" pressure on the rock surface reaches the so-called "water hammer" pressure of pvv(c) and then drops to the nozzle stagnation pressure pressure of pvv(c) and then drops to the nozzle stagnation pressure of approximately 1/2 pv2. (p = fluid density, v = jet velocity, and v(c) = velocity of compression waves in the liquid.) During this initial period of impact, large-amplitude compressive waves are caused to emanate from the point of impingement. Upon reflection off a free surface, these waves become tensile and can cause spalling failures. This mode of failure is usually important with pulsed jet impingement. For continuous jets the spalling effects are small and will be neglected for this study. During the impingement process, the water of the jet flows into the accessible pore space of the rock mass. Since in a continuous jetting process the jet applies a quasi-static pressure loading to the rock surface, the water in the pores is pressurized while the surrounding rock mass is simultaneously stressed. The intent of this paper is to describe the role played by this static pressure loading coupled with the pore-pressure distribution, or pressure loading coupled with the pore-pressure distribution, or the "effective stress," in the first moments of penetration. In studying the process, we will take into account the influence of jet parameters and rock properties. In the course of the impingement process, the jet pressure loading is constantly being redistributed over the crater as it is formed. During this progressive removal of material, erosion is also contributing. The process of erosion is in itself highly complex, so no attempt will be made to characterize it here. EFFECTS OF STATIC PRESSURE DISTRIBUTION-ZERO PORE PRESSURE It has been shown by Leach and Walker that a water jet emanating from the nozzle depicted in Fig. 1 applies a quasi-scatic pressure loading to the surface upon which it is impinging. SPEJ P. 10

scholarly journals Noradrenergic and Cholinergic Modulation of Belief Updating

2018 ◽  
Vol 30 (12) ◽  
pp. 1803-1820 ◽  
Author(s):  
Marieke Jepma ◽  
Stephen B. R. E. Brown ◽  
Peter R. Murphy ◽  
Stephany C. Koelewijn ◽  
Boukje de Vries ◽  
...  
Keyword(s):  
Dynamic Environment ◽  
Theoretical Work ◽  
Learning Rate ◽  
Future Research ◽  
Belief Updating ◽  
Cholinergic Systems ◽  
Rate Study ◽  
P3 Component ◽  
The Impact

To make optimal predictions in a dynamic environment, the impact of new observations on existing beliefs—that is, the learning rate—should be guided by ongoing estimates of change and uncertainty. Theoretical work has proposed specific computational roles for various neuromodulatory systems in the control of learning rate, but empirical evidence is still sparse. The aim of the current research was to examine the role of the noradrenergic and cholinergic systems in learning rate regulation. First, we replicated our recent findings that the centroparietal P3 component of the EEG—an index of phasic catecholamine release in the cortex—predicts trial-to-trial variability in learning rate and mediates the effects of surprise and belief uncertainty on learning rate (Study 1, n = 17). Second, we found that pharmacological suppression of either norepinephrine or acetylcholine activity produced baseline-dependent effects on learning rate following nonobvious changes in an outcome-generating process (Study 1). Third, we identified two genes, coding for α2A receptor sensitivity ( ADRA2A) and norepinephrine reuptake ( NET), as promising targets for future research on the genetic basis of individual differences in learning rate (Study 2, n = 137). Our findings suggest a role for the noradrenergic and cholinergic systems in belief updating and underline the importance of studying interactions between different neuromodulatory systems.

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