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Metodiskie norādījumi saplākšņa paneļu projektēšanai (LVS EN 1995-1-1)
No full textRTU Būvniecības specialitāšu studentiem, studiju procesā izstrādājot uz koka konstrukciju projektēšanu orientētus praktiskus darbus, studiju darbus un inženierprojektus, nereti rodas nepieciešamība detalizēti izprojektēt saplākšņa paneļus. Sastādītajos metodiskajos norādījumos apkopota detalizēta informācija par šādu savienojumu projektēšanu, un tā var sekmēt praktisko darbu izpildīšanas gaitu mācību priekšmetā „Būvkonstrukcijas”, ka arī studiju darbu un projektu kvalitātes paaugstināšanu
The Relationship between Increase of Effort and Attack Speed in Taekwon-do ITF
No full textITF Taekwon-do is a combat sport involving large number of kicks; it requires rapid and forceful kicking (Saulite 2010). One of the main tasks of the training process is to develop kicking speed both in attack and counterattack, where an athlete should react adequately and execute a purposeful element as fast as possible to overtake his opponent (Saulite 2009).
Often an essential element of the training program is a control over athlete's progress in training process. Thus in the weightlifting training (weightlifting is still the most popular way of strength training) progress can be easily controlled by following the increase of weight in a certain number of repetitions of a task. Additional laboratory tests can provide useful information about an athlete’s progress, for instance, whether there is the maximal strength increase at the certain speed or at the certain point of the movement amplitude (Knipse 2008).
Isometric exercise is a form of resistance training in which an athlete uses the muscles of the body to exert a force either against an immovable object or to hold the muscle in a fixed position for a set duration of time. In this type of exercise, the muscle is contracted but does not change length during the exertion of force. Additionally the joint most closely associated with the effort remains static throughout the exercise (Zhou 1996).
Maximal force values can be found in literature sources for eccentric, isotonic and isometric modes (Linnamo 2006, Maietta Latessa 2007). However, there is a lack of data about relationship between muscles' contractile abilities in isometric and dynamic modes.
Kicks are executed in a very short time – 0.2-0.4 s depending on qualification of an athlete (Saulite 2009). Muscle's ability to exert maximal effort also lasts about 0.2-0.4 s. The question to study is how much an effort increase speed influences kicking speed and time for maximal hip flexion and total kick execution time. In the present research relationship between effort increase in hip flexion and kicking speed and time were studied
Lielformāta tirdzniecības objektu izvietošanas teritoriju telpiskās plānošanas vīzija
No full textRakstam ir gan analītisks, gan informatīvs raksturs. Autores atklāj teritorijas jēdziena nozīmi un svarīgumu nekustamā īpašuma objektu plānošanā. Tā ir aktuāla tēma Latvijā sakarā ar straujām izmaiņām nekustamā īpašuma tirgus attīstībā, kā arī vietējiem uzņēmējiem ir jauns un interesants pētījuma objekts, lai paaugstinātu sava biznesa konkurētspēju un precīzāk noteiktu tā izvietojuma vietu. Rakstā ir piedāvātas nekustamā īpašuma objekta stratēģiskā izvietojuma izvēles teorētiskās vadlīnijas un tendences. Pamatojoties uz oficiālajiem statistikas un analītikas datiem, veiktās izpētes rezultāti atspoguļo lielformāta tirdzniecības centru tirgus piesātinājuma līmeni Latvijā un Rīgā no 2007. līdz 2015.gadam salīdzinājumā ar citām Eiropas valstīm. Saskaņā ar Rīgas iedalījumu un lielo tirdzniecības centru iekšējās informācijas datu analīzes darba rezultātiem, Rīgas lielformāta mazumtirdzniecības tirgus sasniedzis brieduma stadiju. Autores pētījuma gaitā secina, ka pašreizējā lielformāta tirdzniecības centru tirgus konkurencei saasinoties, Latvija kopumā ir attīstības stadijā. Vienlaicīgi Rīgas aglomerācija turpina augt un pašvaldības plāno projekta attīstību, kas tālbraucējiem nodrošinātu speciālas stāvvietas izveidi Rīgas nomalē, piedāvājot sabiedriskā transporta reisus virzienā uz centru. Tādējādi attīstot jauktu nekustamā īpašuma objektu izmantošanas projektus. Nākošais lielformāta tirdzniecības centru dzīves cikla solis ir to paplašināšanās, ja teritorija to atļauj, parādoties tirdzniecības parkiem, kas nozīmētu efektīvāku mārketinga darbību telpiskajā plānošanā, piesaistot pircējus no attālākajiem reģioniem un pastiprinot lojalitāti esošajā apkalpošanas tirdzniecības zonā. Iepriekšminēto pasākumu attīstība un turpmāko pētījumu rezultātā noskaidrotie priekšlikumi varētu sekmēt ekonomikas vienmērīgu attīstību visā Latvijā
First Passive House in Latvia: A Real Example
No full textIn 2009 the first building designed according to the passive house concept was built in Latvia.
The main question studied in the paper is conversion of ‘conventional’ (in terms of energy efficiency) building design to passive house standards without loosing the originally planned proportions and aesthetic, functional qualities of the building, and differences of construction process of a building that will comply with passive house standard requirements. Energy saving potential of the Passive House concept compare to building designed according the Latvian legislation is presented. First Blower door test results are oresented
Estimation of the Power and Energy Requirements for Trackside Energy Storage Systems
No full textA trackside energy storage system installed at a DC tram-trolleybus substation is considered from the
standpoint of its ability to capture the braking energy of electric vehicles. The dependence of energy
savings on the power capability and energy capacity of such a system is studied. For this purpose a
method of stochastic modeling is applied. It uses diagrams of experimentally recorded power of
vehicles running within the feeding zone of the substation. The method is verified by applying
probabilistic approach that uses the power probability density functions obtained from the same power
diagrams. The modeling was performed for one substation feeding tram line in the Riga city. Results
of this work allow finding the optimum between energy storage system parameters and recovered
braking energy at given conditions. The proposed method can be applied for energy storage system
sizing not only for current situation, but also for future taking into account growth of transport fleet
and changes in transport organization
Study of Control Strategies for Energy Storage System on Board of Urban Electric Vehicles
No full textThe paper studies various onboard energy storage control strategies for urban electric vehicles. The strategies are theoretically compared in the energy consumption from substation considering losses in the overhead contact line and energy storage system. The study has been made based on the measured speed and power diagrams for one tram route of Riga
Case Study of Non Uniform Temperature Distribution for Industrial Underfloor Heating and Warm Air Heating
No full textAlthough in recent years underfloor heating is common heating system in many European countries for residential buildings, it’s not the same situation in industrial or public premises such as warehouses, exhibition halls, factories, shops. There are several theoretical advantages to use heating system with pipes embedded in concrete floor such as uniform temperature profile, low air speeds, sufficient operative temperature could be achieved with relatively low air temperature thanks to radiant heating and by using existing thermal energy, e. g. from production processes, can additionally decrease energy expenses to almost zero in the best. Low temperature in heating mode and minimum temperature difference between supply and return allows to increase coeficient of perfomance (COP) of heat pump or efficiency of a gas condensation boiler. All of above mentioned advantages lead to more energy efficient heating system, despite that lot of premises instead of utilizing water based industrial underfloor system still uses hot air heating systems with water-air heat exchangers. Case study has been made in existing exhibition hall with installed underfloor heating system seven years ago, vertical temperature differences has been measured, air temperature is kept at about 18C in heating season and ceiling high varies from 8m to 12m. The same measurements been made in warehouse equipped with warm air heaters with water-air heat exchangers. Heat loss due to non uniform temperature distribution was calculated for both cases. Also attention has been given to calculate operative temperature (air and mean radiant temperature) for underfloor heating system and warm air system. Operative temperature can be significantly influenced when using radiant heating, because of higher floor temperature that means that air temperature can be kept at lower level to achieve the same comfort level like using warm air system which leads to more energy efficient heating system comparing to air heating system
Determination of the Necesity of Protection against Lightning and Overvoltage and its Choice
No full textIn this paper a description of the existing situation regarding lightning protection, overvoltage protection, and other protection measures against the dangerous influence of lightning for structures and the service lines that are connected to those structures is given. In this paper two possibilities, how to improve the existing situation, are proposed – by implementation of a special table for a quick choice of the class of lightning protection system and determination of the need for surge protective devices and/or by using intervals of values instead of fixed values of parameters in the calculations, that are necessary for risk assessment
New Method for Derivatization and GC-Analysis of Polar and Non-Volatile Products
No full textNew reagent was developed for GC-silylatio
3-Aminomethyl Allose as a Platform for the Synthesis of N-Heterocyclic Sugar Derivatives
No full textA valuable sugar platform was developed