11 research outputs found
Simulation of soil moisture migration from a point source
A computer model simulating moisture migration in soil from a drip source considering root water extraction (RWE) was developed. The model was formulated using Continuous System Modeling Program (CSMP).A two-dimensional non-linear unsaturated transient flow equation was solved using the principle of mass conservation and Darcy's law on soils of dwarf-apple orchards located in southwestern Quebec. A finite axisymmetric cylinder with homogeneous, isotropic and non-swelling soil was considered for the simulations. No flow conditions across the boundaries of the cylinder were fixed. The initial soil moisture contents in the soil profile observed in the field were input for the simulations.The macroscopic approach was used to compute RWE as a function of (THETA), Z and t. The RWE was assumed to be equal to evapotranspiration (EP) which was estimated using temperatures and the solar radiation index of the location.The moisture contents in the soil profile observed at the termination of emitter discharge were in close agreement with the simulated values. The soil moisture distribution was found to depend on the amount of water remaining in the soil and soil moisture retention characteristics. It is independent of the rate of emitter discharge, the depth of root zone and method of application
Maintenance of periodicals collection: A statistical case study
101-105<span style="font-size:12.0pt;line-height:
115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="" lang="EN-US">Results
of a study carried out to ascertain the active life of periodicals in structural
engineering after taking into consideration the aging factor obsolescence factor,
half life, mean life and utility factor on the basis of citations in periodicals
are presented in this paper. The periodical. âJournal of the Structural
Division' of the American Society of Civil Engineers. New York, 1974 has been taken for the study.
The paper concludes that the periodicals in structural engineering lose their
utility value after 8 years (approx.) of their publication.</span
Lattice location of implanted transition metals in 3CâSiC
We have investigated the lattice location of implanted transition metal (TM) 56Mn, 59Fe and 65Ni ions in undoped single-crystalline cubic 3CâSiC by means of the emission channeling technique using radioactive isotopes produced at the CERN-ISOLDE facility. We find that in the room temperature as-implanted state, most Mn, Fe and Ni atoms occupy carbon-coordinated tetrahedral interstitial sites (TC). Smaller TM fractions were also found on Si substitutional (SSi) sites. The TM atoms partially disappear from ideal-TC positions during annealing at temperatures between 500 °C and 700 °C, which is accompanied by an increase in the TM fraction occupying both SSi sites and random sites. An explanation is given according to what is known about the annealing mechanisms of silicon vacancies in silicon carbide. The origin of the observed lattice sites and their changes with thermal annealing are discussed and compared to the case of Si, highlighting the feature that the interstitial migration of TMs in SiC is much slower than in Si
Emission Channeling with Short-Lived Isotopes (EC-SLI) at CERNâs ISOLDE facility
We give an overview on the historical development and current program for lattice location studies at CERNâs ISOLDE facility, where the EC-SLI (Emission Channeling with Short-Lived Isotopes) collaboration maintains several setups for this type of experiments. We illustrate that the three most decisive factors for the success of the technique are access to facilities producing radioactive isotopes, position-sensitive detectors for the emitted decay particles, and reliable simulation codes which allow for quantitative analysis