Ripples and Grains Segregation on Unpaved Road

Ripples or corrugations are common phenomena observed in unpaved roads in less developed countries or regions. They cause several damages in vehicles leading to increased maintenance and product costs. In this paper, we present a computational study about the so-called washboard roads. Also, we study grain segregation on unpaved roads. Our simulations have been performed by the Discrete Element Method (DEM). In our model, the grains are regarded as soft disks. The grains are subjected to a gravitational field and both translational and rotational movements are allowed. The results show that wheels' of different sizes, weights and moving with different velocities can change corrugations amplitude and wavelength. Our results also show that some wavelength values are related to specific wheels' speed intervals. Segregation has been studied in roads formed by three distinct grain diameters distribution. We observed that the phenomenon is more evident for higher grain size dispersion

Tilstanden i sjøområdene ved Grimstad før start av biologisk renseanlegg på Groos

I 1995 ble Groosefjorden undersøkt for å dokumentere tilstanden før igangsetting av nytt biologisk renseanlegg. Det ble også gjort undersøkelser i andre kystområder i Grimstad kommune for å vurdere tilstanden. Undersøkelsene omfattet vannkjemiske målinger (oksygen, næringssalter, temperatur og saltholdighet), bløtbunnprøver, hardbunnundersøkelser (strandsone og dykk) samt undersøkelse av fiskeforekomster. Undersøkelsene viste at bunnområdene i Groosefjorden var tydelig påvirket av det kommunale utslippet på Groos. Bunnvannet hadde lave oksygenkonsentrasjoner og nær utslippet var bløtbunnsfaunaen dominert av arter som opptrer ved tung organisk belastning, men det var ingen større endringer i tilstanden siden forrige undersøkelse på 1980-tallet. Ved dykking ble det i tillegg registrert hydrogensulfid i sedimentene ved utslippspunktet. I overflatelaget ble det kun funnet svake effekter av utslippet. I Homborsund var det ingen større effekter av utslippet, men resultatene tyder på at området er sårbart for økning i tilførslene

Pulling adsorbed polymers from surfaces with the AFM: stick versus slip, peeling versus gliding

We consider the response of an adsorbed polymer that is pulled by an AFM within a simple geometric framework. We separately consider the cases of i) fixed polymer-surface contact point, ii) sticky case where the polymer is peeled off from the substrate, and iii) slippery case where the polymer glides over the surface. The resultant behavior depends on the value of the surface friction coefficient and the adsorption strength. Our resultant force profiles in principle allow to extract both from non-equilibrium force-spectroscopic data.Comment: 6 pages, 3 figures; accepted for publication in Europhys. Lett., http://www.edpsciences.org/journal/index.cfm?edpsname=ep

Аналіз чинників впливу на процеси функціонування керівної системи підприємств

Мета статті зводиться до вирішення завдання аналізу чинників впливу на керівну систему як регулятор діяльності підприємства та за допомогою використання метода теоретичного аналізу, синтезу та узагальнення розробки їх загальної класифікації.Цель статьи сводится к решению задания анализа факторов влияния на руководящую систему как регулятор деятельности предприятия и с помощью использования метода теоретического анализа, синтеза и обобщения разработки их общей классификации

The Status and Determining Factors to Develop Students Self-Regulated Behavior in Learning among Fourth Generation Universities in Ethiopia

The main objective of the present study was to assess the status and determining factors to develop student self-regulated behavior in learning among fourth generation universities in Ethiopia. To achieve this objective, both quantitative and qualitative data were collected from primary and secondary source of data. The study employed random and purposive sampling techniques to select 270 instructors, 4 department heads and 6 well-experienced teachers. Data from the quantitative survey were analyzed using mean, standard deviation, t-test, analysis of variance and multiple regressions. Qualitative data was analyzed through thematic narration. The study found that the mean score of teacher’s practice of self-regulated behavior in learning was 2.72 and standard deviation 4.379. The independent samples t-test and One-way ANOVA indicated that, there was statistically significant mean difference in gender and educational statues of teachers’ in practice of self-regulated strategies. Women and teachers who had higher educational status performed better than other instructors. Multiple regression analysis indicated teachers’ negative attitude toward their profession and lack of commitment was significant factor for low development of self-regulated behavior in learning in fourth generation Universities in Ethiopia. However, pedagogical knowledge, teaching experience, age and educational was non- significant at P<0.05 level of significance

Overvåking av sjøområdet utenfor Elkem Aluminium, Lista. PAH og metaller i strandsnegl, 1999-2001

Årsliste 2002Rapporten omfatter undersøkelser av metaller og PAH (polysykliske aromatiske hydrokarboner) i strandsnegl (Littorina littorea) i sjøresipienten til Elkem Aluminium ANS Lista. Nærområdet til bedriftens utslipp (st. 1 Ytre Tjuvholmen) var ubetydelig til lite forurenset (tilstandsklasse I) mht. konsentrasjoner av arsen, bly, kadmium, kobber og kvikksølv i strandsnegl og moderat forurenset (tilstandsklasse II) mht. krom. Nærområdet til bedriftens utslipp (st. 1 Ytre Tjuvholmen og st. 2 Haugestrand) var fremdeles meget sterkt forurenset (tilstands-klasse V) mht. PAH. Konsentrasjonene av PAH i strandsneglen varierer signifikant med årstiden med 5-10x høyere konsentrasjoner om høsten (oktober -november) enn om sommeren (juni-august). Stasjon 3 Havik (3 km unna) var moderat til markert forurenset. Stasjon 4 Litlerauna (referansestasjon 10 km unna) var ubetydelig-lite forurenset dvs. at strandsneglene inneholdt konsentrasjoner under grenseverdien satt for antatt høyt naturlig bakgrunnsnivå.Elkem Aluminium ANS List

Escape from a metastable well under a time-ramped force

Thermally activated escape of an over-damped particle from a metastable well under the action of a time-ramped force is studied. We express the mean first passage time (MFPT) as the solution to a partial differential equation, which we solve numerically for a model case. We discuss two approximations of the MFPT, one of which works remarkably well over a wide range of loading rates, while the second is easy to calculate and can provide a valuable first estimate.Comment: 9 pages, including 2 figure

A 2000-year annual record of snow accumulation rates for Law Dome, East Antarctica

Accurate high-resolution records of snow accumulation rates in Antarctica are crucial for estimating ice sheet mass balance and subsequent sea level change. Snowfall rates at Law Dome, East Antarctica, have been linked with regional atmospheric circulation to the mid-latitudes as well as regional Antarctic snowfall. Here, we extend the length of the Law Dome accumulation record from 750 years to 2035 years, using recent annual layer dating that extends to 22 BCE. Accumulation rates were calculated as the ratio of measured to modelled layer thicknesses, multiplied by the long-term mean accumulation rate. The modelled layer thicknesses were based on a power-law vertical strain rate profile fitted to observed annual layer thickness. The periods 380–442, 727–783 and 1970–2009 CE have above-average snow accumulation rates, while 663–704, 933–975 and 1429–1468 CE were below average, and decadal-scale snow accumulation anomalies were found to be relatively common (74 events in the 2035-year record). The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica, demonstrating that the Law Dome record captures larger-scale variability across a large region of East Antarctica well beyond the immediate vicinity of the Law Dome summit. Spectral analysis reveals periodicities in the snow accumulation record which may be related to El Niño–Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO) frequencies