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The Development of an Integrated Geosimulation Environment for Public Transit Analysis and Planning
No full textThis paper describes an integrated software environment for multi-modal public transit simulation based on the principles of geosimulation that integrates the capabilities of multi-agent systems, GIS and interactive visualization. The goal of the presented research is to explore possibilities of population in one of Latvia’s planning regions, called Vidzeme, to access state/municipal and other services by using public transport. In order to achieve the defined goal, an integrated simulation environment for public transit analysis and planning is developed
Characteristics of Illite Clay and Iits Use for High - and Low Temperature Ceramics
No full textTwo ways for practical use of illite clays were
studied: chemical treatment and non-conventional application to
promote sintering and formation of mullite –ZrO2 ceramics
It is shown that treatment of the illite Quaternary clay by
KOH leads to forming of the weakly connected illite structure.
That results in significant decrease of sintering temperature of
the obtained ceramic materials. Use of Devonian clay as additive
8 wt.% for mullite – ZrO2 ceramics leads to growth of its density
and considerable increase of the compressive strength by
maintenance of ZrO2 in tetragonal crystalline form
Minerālo piedevu un izejvielu dispersitātes ietekme uz kordierīta keramikas īpašībām
No full textDarbā apskatītas kordierīta keramikas
iegūšanas iespējas, aizstājot daļu nepieciešamo sintētisko izejvielu
ar māliem un dažādiem Latvijas dolomītiem. Iegūtie izejvielu
pulveri tika malti divos režīmos, pēc malšanas noteikts efektīvais
daļiņu diametrs. Šī darba rezultāti parādīja, ka mālu
pievienošana konkrēta sastāva paraugiem uzlabo to spiedes
izturību. LTIK un SEM attēlu analīze norāda uz malšanas laika
palielināšanas pozitīvo ietekmi, samazinot iegūstamo keramisko
paraugu porainību un uzlabojot graudu sablīvēšanos
Latvijas karbonātiežu izmantošanas iespējas kaļķu saistvielu ražošanai
No full textDarbā aprakstīti kaļķu saistvielu klasifikācijas
principi, saistvielu iedalījums un reglamentētās īpašības atbilstoši
saistošajiem standartiem. Raksturoti kaļķu saistvielu ražošanai
Latvijā pieejamie nogulumiežu derīgo izrakteņu resursi.
Izvērtējot eksperimentālās izpētes datus, savstarpēji salīdzināta
romāncementa iegūšanas iespējas no dolomītmerģeļa un
mākslīgā dolomīta-mālu izejvielu maisījuma. Secināts, ka no
dolomīta-mālu maisījuma iespējams iegūt līdzvērtīgu saistvielu
ar priekšrocībām nemainīga sastāva nodrošināšanai
Sulphur Containing Derivatives of Humic Substances and Their Use for Remediation of Contaminated Environments
No full textDerivatives of humic substances containing sulpho-,
and thiol groups were synthesized and their properties were
analyzed for their elemental composition; functional group
content changes in spectral characteristics. The derivatives of
humic substances showed significant differences in the number
and in the ability to interact with the metal ions, which were
reflected in their complexation properties towards metal ions.
FTIR spectra gave evidence of the presence of metal ions,
strongly bound and protected in inner sphere complexes. The
obtained derivatives of humic substances can be used for
remediation of environments contaminated with heavy metal
ions
Comparative Study on Bacteria Colonization onto Ceramic Beads Originated from Two Devonian Clay Deposits in Latvia
No full textCeramic carriers for immobilization of
microorganisms are widely used in wastewater treatment, air
biofiltration technologies, etc. The aim of this study was to
compare seven different types of ceramic beads fabricated from
two types of Devonian clay, in terms of their appropriateness for
bacteria cell attachment and further use for soil/air cleaning
technologies. The effect of different ceramic beads on the
microbial growth and biofilm formation was studied for pure
culture Pseudomonas putida MSCL 650 and for bacteria
consortium MDK.EKO-7. The highest CFU number recovered
from the bead surfaces after 72h cultivation, was in the sets No. 4,
6, and 7, corresponding to one Liepa red and two Planci clay
samples, respectively. Besides, a fluoresceine diacetate (FDA)
hydrolysis activity of the attached bacteria served as a criterion
of biofilm formation. Statistically significant differences of FDA
hydrolysis were shown for both, ceramic beads with biomass and
without it. Among ceramic beads without biomass, half-spheres
of Liepa red clay beads and Planci clay beads significantly
differed from other tested samples. These data could point to the
notable differences between physical-chemical properties of these
beads, which stimulated abiotic FDA hydrolysis. Among ceramic
beads with biomass, FDA hydrolysis activity on the half-sphere
beads was significantly (p<0.05) higher than that on the surface
of the whole sphere beads fabricated from Liepa red clay. SEM
micrographs of the bead surface showed uneven distribution of
bacteria on the surface. The craters (pores) of ceramic bead seem
to be the most appropriate sites for bacteria attachment.
Experiments on dehydration of the attached P. putida at 22 °C
showed a decrease of cell viability down to zero in 16 days. It was
concluded that Liepa red clay and Planci clay are appropriate for
carrier fabrication. The quality of ceramic carrier is dependent
on the technological process of ceramic production, bead
composition and conditions for biofilm formation
Trend of Air Pollution during Electric Arc Welding and Oxyacetylene Cutting
No full textThe present work comprises the unpublished results
from the investigation of the air pollution caused by the electric
arc welding and oxyacetylene cutting. These results have been
obtained in the process of creating of the database, which
contains information on the pollutants resulting from
technological operations. In the present research the gained
experience has been used. In the experiments the technological
conditions and circumstances for carbon oxide, carbon dioxide,
acrolein, nitric oxide and dust supply have been changed. During
this research has bin made confrontation of other researcher’s
results
Pilsētu un reģionu attīstības mijiedarbības sociāli ekonomiskie aspekti: zinātniski lietišķā monogrāfija
No full textZinātniski lietišķās monogrāfijas ietvaros pētījuma autori izvērtējuši jautājumus, kas saistīti ar nozīmīgākajiem valsts nozīmes pilsētu un lauku teritoriju mijiedarbības sociālajiem, ekonomiskajiem aspektiem, izstrādājuši rādītāju sistēmu pilsētu un lauku teritoriju mijiedarbības uzraudzībai un izvērtēšanai, kā arī sagatavojuši priekšlikumus pilsētu un lauku attīstības optimizācijai ilgtspējīgas attīstības kontekstā
Methods and Software Tools Used to Designate Geometry for Regional Hydrogeological Model of Latvia
No full textIn 2012, the hydrogeological model (HM) LAMO of
Latvia has been developed by scientists of Riga Technical
University (RTU). LAMO comprises an active groundwater zone
that provides drinking water. 3D-body of LAMO is
approximated by the 951×601×25 size finite difference grid. Its
plane approximation step is 500 metres and HM accounts for 25
geological layers.
The commercial software Groundwater Vistas (GV) is used to
run LAMO. The GV system contains tools used worldwide for
hydrogeological modeling.
The most time consuming and troublesome part of developing
a HM is to designate its geometry that is represented by
thicknesses of geological layers composing the HM body. For
LAMO, most of these layers are outcropping. They are not
continuous and, for this reason, they are not present everywhere
in the area of the HM. After emerging at the surface, such layers
have zero thickness.
Thicknesses of the layers are not used by GV as initial data.
A modeller must prepare the set of z-maps that presents elevation
surfaces of the layers. The GV system uses z−maps for obtaining
thicknesses of the layers.
To prepare z-maps for primary geological layers, three steps
of data interpolation were performed:
1. selecting and checking borehole data that describe
stratigraphy of the geological environment; the EXCEL
system was applied, to carry out this step;
2. by using the graphical system SURFER, the preliminarily
set of z-maps was prepared;
3. the final version of z-maps was obtained by the Geological
Data Interpolation (GDI) system.
It was rather difficult to create z-maps for the Quaternary
layers, because borehole information describing their geometry
was waste and contradictory. For this reason, mainly pointwise
data and a few lines were applied as sources for obtaining z-maps
of the Quaternary System