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Process and Importance of Setting a Sustainable Development as a Strategic Target for Technical Universities
No full textUniversities educate society and have a major influence on the economy by setting the trends for future development. To ensure rapid and well-considered development of technology, environment and economy in the long run, Universities must have strategy with clearly defined goals. And if Universities really care for cleaner and healthier environment - one of these goals must be sustainable development.
This paper answers the following questions – what is concept of sustainable development, what role does Universities have in promoting the concept and how to incorporate the concept within strategy of the University and afterwards measure it
Investigation of Structure and Physical Properties of Prpyanylidene Fragment Containing Molecular Glasses with Trityloxyrthyl and Tert-Butyl Groups
No full textLow Temperature Properties of Rejuvenated 100% Reclaimed Asphalt Pavement Mixtures
No full textNine differently originated softening agents were tested with 100% RAP mixtures to evaluate their effect on penetration at two temperatures and low temperature embrittlement. Penetration Index (PI) was evaluated as an indicator for rejuvenation effectiveness and to predict the cracking potential. Low temperature mixture performance was tested at -10°C through determination of indirect tensile strength and creep compliance. The mixture test results confirmed the PI results and showed that the use of four from the tested rejuvenators reduced the binder consistency to the necessary level and reduced the susceptibility of the recycled mixture to low temperature embrittlement
Supply Air Parameters Interaction on Thermal Performance of IEAC
No full textIn an indirect evaporative air cooling (IEAC) installation air
is cooled by means of adiabatic humidification process. By
passing over an air/air heat exchanger this air cools the supply
or mixed (supply and extracted) air. A clear interaction can be
observed between the relative humidity and temperature of the
supply air and the thermal comfort implemented in the
building. To be able to predict the performances of this
technique well, a good knowledge of the supply air relative
humidity and temperature are thus important. Paper presents
the results of measurements carried out in summers of 2008,
2009 and 2010 in a simulated nonresidential building in 3
cities of Latvia: Riga, Liepaja and Gulbene which make
indirect evaporative cooling usable. An evaluation of the
indoor summer comfort is made and the interaction between
the thermal performance and outdoor air parameters (humidity
and temperature) are investigated.
Work actuality is based on the Latvian Cabinet of Ministers
regulation No. 534 Regulations Regarding Latvian Building
Code LBN 231-03 "Residential and public buildings heating
and ventilation" 118th paragraph, “If the air handling
equipment for air cooling assess whether the compression
cycle cooling techniques can’t be replaced by a direct or
indirect adiabatic cooling techniques to minimize the impact
on the environment.” Topic view and updating gives more
understandable operating positive and negative aspects, which
in turn give engineers new viewpoint to the evaporative
cooling as the primary cooling type of General Regulation
Optimization of Solar Thermal System's Pipelines Insulation
No full textThe paper presents the results of research work on the effective use of solar collectors which was realized in the solar energy testing polygon at the Institute of Physical Energetics.
A certain proportion of the energy generated by solar thermal system is spent as the heat losses in pipelines between the solar energy absorbing device and the heat-accumulation tank.
Insulation of solar thermal system’s pipelines is necessary for both outdoor and indoor pipes. Outdoor heat pipes insulation reduces systems heat losses outside, while, indoor heat pipe insulation reduces value of unnecessary energy distribution inside in the summer period.
The dependence of pipelines heat losses from the pipelines insulation type has been determined with the PolySun simulation program. The most popular heat pipes insulation materials in Baltic region were examined and compared. The results of comparison were summarized in graphic form taking in account the thermal conductivity coefficient and the prices. The amount of absorbing energy values and heat losses have been calculated and presented in the graphical form. As a result the method for determination of the most effective insulation types for solar thermal system’s pipelines has been developed.
Valsts parāda struktūras un valsts kredītreitinga analīze
No full textKredītreitings ir plaši izmantots līdzeklis, lai novērtētu, tajā skaitā valsts finanšu stabilitāti. Raksta mērķis ir novērtēt iespēju izmantot kredītreitingus valsts finanšu neatkarības no ārzemju kreditoriem izvērtēšanai. Lai novērtētu, cik nozīmīga ir vidējo ārējā parāda īpatsvars, tika izmantots Studenta t – tests vidējām vērtībām un Fišera F-tests standartnovirzēm. Nelielas determinācijas koeficienta vērtības, kas atbilst lielam punktu novirzēm no regresijas līnijas, liecina par ārēja parāda daļas ietekmi kredītu reitingu neliela mērā. Tādējādi, var izdarīt secinājumu, ka reitings nevar pats par sevi tikt izmantots, ka viens no parametriem, kas nosaka valsts finanšu drošību no valsts parāda vadības viedokļa
The Effect of the Flows of Information on Residential Electricity Consumption: Feasibility Study of Smart Metering Pilot in Latvia
No full textThe aim of this research is to describe options and solutions for the effective communication and cooperation engaging stakeholder in the smart metering pilot in Latvia (i.e. electricity consumers, electricity suppliers, smart meter suppliers and scientific research institutions) using a variety information resources (such as detailed electricity bills, e-mails, mobile applications, web portal, informative workshops, open days, e-journals, information sheets, brochures, discussion clubs, videos, etc.). This communication in terms of each stakeholder can be defined as the system through which qualitative information is created and provided in accessible formats, communications forms, are disseminated to the public and preserved for future use. In this research emphasis is being placed on Web-based stakeholder communication.
This pilot is the first attempt to promote broader household involvement in energy efficiency measures using smart technologies aimed at encouraging consumers to reduce energy consumption. Provision of information is the „keyword” of this pilot to strive for a very high added value – to develop the concept of innovative and creative awareness-raising smart systems use aiming at raising electricity end-user awareness of energy efficiency and green thinking. This is what we want to contribute in this Project. Furthermore, it will contribute to higher scientific, social and economical added value.
Latvia is currently on the initial stage of smart metering implementation in households. In this context, related bahavioural studies will contribute to the development of appropriate energy efficiency measures in households that are highly important for Latvia. It can serve as a further contribution to policy makers for determining a legal framework for smart metering implementation in Latvia in the next few years
Kūdras izmantošana siltumizolācijas materiālu ražošanā. Aktivētās kūdras saistvielas iegūšana un tās izmantošana kūdras-kokskaidu siltumizolācijas kompozītos
No full textPar aktuālu problēmu mūsdienās ir kļuvusi energoefektivitātes nodrošināšana ēkām un būvēm. Latvijas siltumizolācijas būvmateriālu tirgus mūsdienās lielākoties ir pārstāvēts ar ārzemēs ražotiem siltumizolācijas materiāliem un to izejvielām. Pētījuma gaitā tika apskatīt vietējie resursi un izejvielas, kas var tikt izmantoti siltumizolācijas materiālu ražošanā.
Latvijas dabas bagātība ar lielu potenciālu siltumizolācijas būvmateriālu ražošanā ir kūdra, šī resursa aptuvenie apjomi valstī ir 1.7 miljardi tonnu, aizņemot apmēram 10% no valsts teritorijas. Latvijā plaši attīstīta ir kokapstrādes rūpniecība, kuras blakusprodukts – kokskaidas tika izmantots pētījuma gaitā kā pildviela kūdras-kokskaidu siltumizolācijas kompozītmateriālā.
Šī darba mērķis ir praktiski iegūt aktivētās kūdras masu ar saistvielas īpašībām un radīt ekoloģiski tīru siltumizolācijas materiālu ar 100% vietējo izejvielu izmantošanu.
Ar kūdras aktivāciju pirmkārt saprot dažādu kūdras sastāvdaļu izteiktāku darbību dažādos procesos, esošo raksturīgu īpašību paaugstināšanos un jaunu īpašību atklāšanu. Pastāv vairāki kūdras aktivācijas veidi, tostarp: mehāniskā, termiskā, ķīmiskā un kombinētā. Pētījuma ietvaros tika izmantota kūdras mehāniski-termiskā aktivācija ūdens vidē ložu planetārajās dzirnavās. Dažādu materiālu īpašības ir tiešā veidā saistītas ar to sastāvdaļu un izejvielu īpašībām. Izejvielu kvalitātes paaugstināšana ļauj ne tikai uzlabot izstrādājumu kvalitāti, bet arī lietderīgāk izmantot dabas resursus. Risinot cilvēces globālās problēmas, katra atsevišķa resursa lietderīgāka izmantošana kļūst arvien aktuālāka.
Kūdras aktivācijas režīmu novērtēšanai tika izgatavoti un pārbaudīti spiedē kūdras-kokskaidu kompozītmateriāla paraugi. Iegūtā aktivētā kūdras masas daļiņu izmēru un homogenitātes izmaiņas atkarībā no aktivācijas laika tika vizuāli novērtētas izmantojot elektrisko mikroskopu.
Pētījuma gaitā tika praktiski iegūti dažāda tipa siltumizolācijas materiāli un aktivētās kūdras masa ar saistvielas īpašībām, kas var tikt plaši izmantota arī citu materiālu radīšanā.
Iegūtās vielas un materiāli:
-Aktivētās kūdras masa ar saistvielas īpašībām, var tikt izmantota būvmateriālos kā saistviela, kā arī laku, krāsu un pārklājumu sastāvdaļa;
-Kūdras granulas, var tikt izmantotas kā beramā siltumizolācija (siltumvadītspējas koef. 0.07 W/(mK)) un vieglo betonu ražošanā;
-Kūdras-kokskaidu siltumizolācijas plātnes (siltumvadītspējas koef. 0.05 W/(mK));
-Kūdras-kokskaidu kompozītmateriāls ar stiprību spiedē līdz 1.75 MPa pie 10% deformācijām, kas var tikt izmantots ka konstruktīvai materiāls.
Darba gaitā iegūtie materiāli ir ekoloģiski tīri un pilnība pārstrādājami, kas atbilst ekoloģiskās būvniecības pamatprincipiem. Visas izmantotās izejvielas ir vietējas un plaši izplatītas, kas materiāla ražošanas gadījumā sekmēs valsts ekonomikas attīstību.
Problems of Synthesis of Underwater Robots
No full textThe first part of this study was investigations the optimization task by using optimal control theory. The high speed task for energy harvesting from fluid flow is solved for two types of control action limits. One limit type is the boundary value of interacting surface, the second type – transition switching velocity from one surface level to other. It is shown that optimal area control law has one or two limits. In the second part of study problem of correct explanation of interactions between flow and surface is discussed
