18420 research outputs found
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Latvijas kvarca smiltis stikla ražošanai
No full textLatvijas teritorijā relatīvi plaši izplatīta minerālā izejviela ir smiltis. Rakstā dots pārskats par Latvijas devona (Bāles atradne) un juras perioda (Skudru atradne) kvarca smilšu ķīmisko un granulometrisko sastāvu. Latvijas kvarca smiltis salīdzinātas ar Baltijas reģiona atradnēm un atzīmēta iespēja tās izmantot stikla ražošanai. Parādīta nepieciešamība Latvijas smilšu attīrīšanai – granulometriskai un ķīmiskai sastāva uzlabošanai. Aprakstītas galvenās kvarca smilšu bagātinašanas metodes un prasības bagātināšanas rūpnīcām
Kūdras sorbenti arsēna savienojumu adsorbcijai
No full textArsēna savienojumu adsorbcijai sintezēti ar dzelzi modificēti kūdras sorbenti, ar slāpekļa funkcionālajām grupām modificēti kūdras sorbenti un dzelzs humāts. Pētīta arsēna savienojumu adsorbcija uz purva kūdras un uz modificētiem kūdras sorbentiem. Augstākā adsorbcijas kapacitāte novērota, izmantojot ar dzelzi modificētus kūdras sorbentus. Uz ar dzelzi modificētiem sorbentiem adsorbcija pētīta atkarībā no šķīduma pH un temperatūras. Tiek uzskatīts, ka adsorbciju ietekmē modifikācijas metode un dzelzs saturs. Adsorbcija pie dažādām šķīduma pH vērtībām ir atkarīga no arsēna jonu formas šķīdumā. Šī pētījuma rezultāti var tikt izmantoti, lai izstrādātu jaunu kūdras sorbentu, ko varētu izmantot dzeramā ūdens attīrīšanai no arsēnu saturošiem savienojumiem
Siltumenerģijas patēriņa noteicēju un termoregulatoru izmantošanas iespējas dzīvojamo māju energoefektivitātes uzlabošanā Latvijā
No full textSabiedrība enerģiju izmanto trīs galvenajās nozarēs – siltumapgādei,
transportam un elektroapgādei. Latvija atrodas Eiropas ziemeļu daļā
un tās lielākais enerģijas patēriņa īpatsvars ir siltumenerģijas ražošana
– tas sastāda 63% no kopējā apjoma. Dzīvojamo māju siltumapgādei
izlieto apmēram 70% no siltumenerģijas ražošanas apjoma. Dzīvojamās mājas minimālo energoefektivitātes prasību nodrošināšanai no 2009.gada
dzīvokļu īpašnieki var piedalīties valsts programmā “Daudzdzīvokļu
māju siltumnoturības uzlabošanas pasākumi”. Viens no programmas
atbalstītākajām aktivitātēm ir apkures sistēmas nomaiņa vai pārbūve.
Dzīvokļu īpašniekiem ir jābūt iespējai pašiem regulēt siltuma patēriņu
dzīvojamās telpās
Improvement and Extension of ETRS 89 in Latvia and Lithuania Based on the NKG 2003 GPS Campaign
No full textLatvijas ģeodēziskā pamattīkla uzmērīšanas un aprēķināšanas darbu apraksts, kas ir bāze Latvijas koordinātu tīkla nultās klases punktiem. Punkti atbilst EUREF iedalījuma B klases punktiem, kas globāli nodrošina 1 cm precizitāti novērošanas laikā. Šie punkti ir ETRS 89 realizācija Latvijas teritorijā, to apstiprina EUREF 2006.gada rezolūcija Nr.1. (skat. EUREF mājas lapā http://www.euref.eu/
Nano-Cones Formed on a Surface of Semiconductors by Laser Radiation: Technology, Model and Properties
No full textThe new laser method for nanostructures formation on a surface of semiconductors Si, Ge, GaAs and SiGe, CdZnTe solid solutions is proposed. For the first time was shown the possibility of graded band gap structure formation in elementary semiconductors. Thermogradient effect has a main role in initial stage of nano-cones and graded band gap structure formation by laser radiation in semiconductors
Optical Properties of Nanocones Formed on a Surface of Semiconductors by Laser Radiation: Two Stage Model
No full textOn the basis of analysis of experimental results on elementary semiconductors such as, Si and Ge, and their SiGe and CdZnTe solid solution a two-stage mechanism of nanocones formation on the irradiated surface of semiconductors by Nd:YAG laser is proposed. Such properties are explained in the frame of Quantum confinement effect. The mechanism of nanocones’ formation on the irradiated surface of Si0.7Ge0.3 solid solutions is characterized by two stages – Laser Redistribution of Atoms (LRA) and Selective Laser Annealing (SLA). The first stage of nanocones’ growth - LRA is characterized by formation of top strained layer, enriched by Ge atoms in Si0.7Ge0.3 due to their drift to the irradiated surface in temperature gradient field induced by laser radiation. The main role in this process has Thermogradient effect. LRA is a nonlinear optical process: concentration of Ge atoms in the top layer of SiGe solid solution increase with number of laser pulses and at the same time absorption coefficient of the top layer increases. As a result, LRA stage gradually transits to SLA stage. The second stage of nanocones’ formation on the irradiated surface of semiconductor - SLA is selective laser absorption of the light by the top stained layer with further mechanical plastic deformation of the top layer due to relaxation of the mechanical compressive stress arising between these layers due to mismatch of their crystal lattices and heating up the top layer. SLA occurs due to higher absorption of the laser radiation by the top layer than the buried layer. A similar two-stages’ model can be used for nanocones’ formation by laser beam on ternary component solid solution Cd0.9Zn0.1Te. In the case of the elementary semiconductors, at the first stage of the process a thin top layer is formed by mechanical compressive stress due to separation of interstitials and vacancies in gradient temperature field on the irradiated surface of the semiconductors. At the second stage of the process nanocones are formed on the irradiated surface of the semiconductors due to plastic deformation of the top layer in the same way as in the previous case with semiconductor solid solutions. The model is confirmed by “blue shift” of photoluminescence spectrum, “red shift” of LO line in Raman back scattering spectrum of Ge crystal and non-monotonous dependence of Si crystal micro-hardness as function of the laser intensity
Improvement of Energy Efficiency by Using Proportional Pressure Control Mode at the Second Stage Pumping Stations in Public Water Supply
No full textThe goal of the research is estimation of the energy efficiency improvement potential when the proportional pressure control mode is used at the second stage pumping stations in public water supply systems. For this reason, a large number of energy cost analyses have been made for different centrifugal pumps and regression equations with coefficients of determination have been derived.
As the result, the savings’ potential of energy consumption has been defined, if proportional pressure is used instead of constant pressure. The decrease of water leakage has also been determined when the proportional pressure control mode is applied
Identification of Relations between BDI Logic and BDI Agents
No full textBDI (Beliefs, Desires, Intentions) is one of the most popular intelligent agent architectures which was inspired by multi-modal BDI logics. The main idea behind BDI is to implement system’s behaviour by specifying it as a set of mental objects. This allows designing systems at a high level of abstraction which come closer to a human-like thinking. Although this architecture has been rapidly developing for about 20 years, its relevance to BDI logic is still arguable. This paper describes the basics of modal logic and main inference algorithms. Main concepts of BDI agents are presented and their relationships with BDI logic are discussed. Finally advantages and disadvantages of implementing BDI interpreter as a theorem prover are discussed
Stress State and Strength of the Piezoceramics at Static Load
No full textThe strength of piezoelectric transducer sat static loading and vibrations was investigated. The theoretical model of strength for
piezoceramics stripe glued to structural element was developed. Using the concept of ‘weak chin’ and the results of stress state analysis of
three-layers structure with the cracks in one of layers. The general tendencies of effect of this structure parameters were defined. The effect
of mechanical loading of piezoceramics transducer to its stress state and destruction can be decreased by rational selection of its
geometrical parameters and thickness of coupling layer