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Analysis of a Cavitation for the ESS Target Model
No full textIn the present work some aspects of cavitation influence on the European Spallation Source (ESS) liquid metal target are investigated. The analysis is based on a calculation of the bubbles’ radius change for bubbles moving along a changing pressure field.
The shape of pressure field is obtained from numerical investigation of fluid flow in the ESS model. A simplified pressure model is used to find how a bubble’s radius depends on pressure and temperature. The main goal of this work is to determine conditions (such as bubble initial radius, temperature, pressure) leading to bubble’s growth or collapse. In all cases “stability” curves (curves dividing area of bubble growth from area of bubble collapse in dependence of some parameters) are constructed
Latvijas pilsētu sociālekonomiskās attīstības līmeņa un tempa novērtējums
No full textRaksta mērķis ir veikt Latvijas lielāko pilsētu sociālekonomiskās attīstības novērtējumu. Pēdējo 10 gadu attīstības tendences atspoguļotas attīstības līmeņa-tempa matricā, grafiski atainojot arī pilsētas lielumu pēc iedzīvotāju skaita. Novērtējums norāda uz būtiskām pilsētu un līdz ar to reģionālās attīstības atšķirībām, līderpozīcijās nostādot pilsētas 70 km rādiusā ap Rīgu, kā arī Valmieru, Dobeli, Cēsīm un Saldu. Veiktā analīze apliecina, ka attīstības līmeņa-tempa matrica ir praktiski izmantojams rīks pilsētu sociālekonomiskās attīstības novērtēšanai
On the Power of Topological kernel in Microarray-Based Detection of Cancer
No full textIn this paper we propose a new topological kernel for the microarray-based detection of cancer.
During many decades microarrays were a convenient approach in detecting and observing tumor-derived proteins and involved genes.
Despite of its biomedical success microarray-based diagnostics is still out of common sense in practical biomedicine due to the lack
of robust classification methods that would be capable of correct and insensitive to underlying distribution diagnosis
of unseen serum samples. This dismal property of microarray datasets comes from probabilistically infeasible difference between cancer
specific and healthy samples where only very small number of (anti)genes has prominent tumor-driven expression values. Kernel methods
such as SVM partially address this problem being a "state-of-art" general-purpose classification and regression toolbox. Nevertheless,
a purely performed normalization or preprocessing steps could easily bias encoded via SVM kernel similarity measures preventing from proper
generalization on unseen data. In this paper, the topological kernel effectively addresses the above mentioned issue by incorporating
indirect topological similarities between samples and taking into consideration ranking of every attribute
within each sample. The experimental evaluations were performed on different microarray datasets and verify that proposed kernel
improves performance on purely conditioned and even very small datasets resulting in statistically significant P-values.
Finally we demonstrate that proposed kernel works even better without applying cross-sample normalization and rescaling of input space
Sistēmdinamika vides inženierzinātņu studentiem
No full textLai izprastu jebkuras sistēmas uzvedību un būtu iespējams prognozēt izmaiņas tajā dažādu ārējo un iekšējo ietekmju dēļ, ieskaitot minēto efektu, pagājušajā gadsimtā radusies un pašlaik pilnveidojas sistēmdinamikas modelēšanas un analīzes teorija. Grāmata iekļauj sistēmdinamikas modelēšanas pamatu izklāstu un piemērus
Dwelling Buildings’ Energy Certification by Total Energy Consumption
No full textOne of the requirements of the Directive 2002/91/EC on the energy performance of buildings is introduction in the EU member countries of energy certification of buildings. It has to be implemented starting from 2006. In Latvia the energy certification scheme for dwelling buildings was developed in RTU in 2000 and successfully implemented in Ogre in 2002-2004. The existing buildings’ energy certification scheme takes into account only energy consumption of space heating and hot water supply. In order to comply with the requirements of the certification by total energy consumption the building energy certification scheme has to consider also gas and electricity consumption. The data on buildings total energy consumption were gathered for Ogre buildings in 2004/2005.The paper for the first time presents and analyses measured data on total building energy consumption in Latvia. The paper gives theoretical basis and methodology for incorporation of electricity and gas consumption in the standardized annual specific energy consumption used as criterion in the existing building energy certification scheme
Magnetic Field Control of Combustion Dynamics of the Swirling Flame Flow
No full textMagnetic field effect on combustion dynamics of the swirling flame flow is studied experimentally with the aim to obtain a cleaner and more effective combustion of a renewable fuel (wood pellets), providing a joint research of magnetic field effects on the swirling flame velocity field formation, processes of heat/mass transfer and combustion of volatiles at different stages of the wood fuel burnout
Teaching Applied Geo Physics at Rtu: the Basics for a Fast, Green, not Expensive Subground Investigation Method
No full textGeophysical methods are applied to determine a spatial model of the underground, to locate fault zones, to investigate the regional ground-water system, or to derive lithological parameters. In other words, applied geophysics provides the distribution of physical parameters of the subsurface by surveys at the earths' surface without destroying soil formations. In Latvia expert companies of on geophysics surveys are few.
Thus, it is important that environmental experts have knowledge in this, and that Latvia, as a country, has access to international expertise.
During study introduced hereto we compared the geophysics course in the Riga Technical University (RTU) with similar courses in seven European universities, gathering information through websites. We collected information about duration of the courses, learning objectives, topics, teaching methods, credit points etc. As a result, proposals, how to improve the course in RTU were elaborated
Latvijas nekustamā īpašuma tirgus ilgtspējīgas sociāli ekonomiskās attīstības modelis
No full textPētījumā tiek analizētas nekustamā īpašuma nodokļa izmaiņu īpatnības, no kā var secināt - šī nodokļa piemērošana arī būtiski ietekmēs gan nekustamā īpašuma tirgus attīstību, gan arī sekundāri tautsaimniecību kopumā
Biroja krēsla dizains un ergonomikas principi
No full textPirms uzsākt krēsla dizaina veidošanu, dizainerim ir jāņem vērā daudz un dažādi faktori, kas spēj krēslu padarīt ērtu un komfortablu jebkuram lietotājam. Ir skaidrs, ka grūti radīt produktu, kas būtu piemērots jebkuram cilvēka auguma tipam - gariem vai īsiem, slaidiem vai apaļākiem. Tieši tādēļ ir veikta izpēte par galvenajiem faktoriem, kas ietekmē krēsla ērtumu- sēdēšanas procesa dinamika, sēdekļa augstums, sēdekļa dziļums, sēdekļa atzveltne, roku balsti un virsmas apšuvums
Possibilities of Use of Game Theory in Real Estate Market
No full textThere hasn't been any serious scientific study of real estate price decision strategy with the application of game theory in Latvia. The purpose of this study is to explore and describe land and real estate pricing strategies using a game model. The case study proves that the methods of the game theory are effective in a real life situation and can be successfully applied to solving similar problems