18420 research outputs found
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GSM – Railway Network Basics
No full textApskatīta perspektīva dzelzceļu automātikas, telemehānikas un sakaru sistēma, kas bāzēta uz GSM-Railway standarta pamata.
Lekciju konspekts satur informāciju pēc sekojošām nodaļām:
1. GSM-Railway standarta apskats.
2. GSM-Railway tīkla projektēšanas pamati.
3. Radio viļņu izplatīšanās matemātiskie modeli.
Pielikumos ir paradīti signāla uztveršanas punktā jaudas atkarības no distances skaitlisku aprēķinu piemēri (MathCAD), atbilstoši dažādām radio viļņu izplatīšanās modeļiem
Daudzvalodu e-vietnes koncepcija operacionālo IT risku pētīšanai
No full textDotajā rakstā ir aprakstīta efektīvu pētījumu nodrošināšana operacionālo IT risku pārvaldības jomā specializētā pētnieciskā digitālā daudzvalodu vidē. Tiek pētītas mūsdienu IT izmantošanas tendences e-vietņu izstrādē, Web 2.0., sociālo tīklu, tīmekļa žurnālu, viki u.c. tehnoloģijas. Uz veikto pētījumu pamata tiek izstrādāta daudzvalodu e-vietnes koncepcija, kā arī piedāvāti šīs koncepcijas praktiskās realizācijas projektu risinājumi. Veiktais darbs ir turpinājums Latvijas monetāro un finanšu institūciju operacionālo IT risku pārvaldības pētījumam, bet tajā pašā laikā var tikt pielāgots citām pētnieciskajām nozarēm
Temporal Data Mining for Identifying Customer Behaviour Patterns
No full textThis paper addresses the application of Data Mining technologies in the task of price formation and adjustment for the existing manufacturing plant through studying customer behaviour. The problem of fine price adjustment is especially topical for medium-size and large manufacturing plants. The research is aimed at developing a technique providing a validated recommendation or decision evaluation in the task of price adjustment. The introduced concept of sales volume behaviour profile is based on customer behaviour analysis. A sys-tem to frame and process multidimensional time-series is proposed and imple-mented. A practical result of the study is a software tool enabling the manager to obtain the prediction of the changes in sales volumes for the target decision using their behaviour profiles
Lowering of EMI Noise in Boost Type PFC by the Use of Spread Spectrum
No full textThe implementation of spread spectrum technique within the boost type power factor corrector (PFC) for its EMI reduction is studied. The study involves the experimental measurements, SIMULINK simulations and the calculations of attenuation of harmonics of switching frequency spectrum. The results show that appreciable EMI attenuation can be achieved by the use of spread spectrum gained with sinusoidal frequency modulation. The modulating signal’s frequency and the deviation manifest themselves as the main factors that influence the degree of EMI attenuation. Some adverse affects of frequency modulation are also discussed. It has been proved, that the efficiency of PFC under study slightly decreases with the increase of frequency deviation. SIMULINK model of boost PFC was also designed. The fact that the simulation data and the experimental ones are almost identical proves that the model is relatively precise and could be used as the tool for analysis and for further investigation in order to examine other types of modulating signals and their effects. Ill. 4, bibl. 8 (in English; abstracts in English, Russian and Lithuanian)
Characterization of Material Properties by means of Small Specimens
No full textDaudzslāņaina materiāla īpašību novērtē, kas tiek armēts ar vienā virzienā oglekļa šķiedru un slogots dažādos veidos, tiek izvērtēta šajā publikācijā. Materiāla elastīgas īpašības tika iegūtas izmantojot divas dažādas metodes – tradicionālo statiska slogojuma pārbaudi, balstoties uz ASTM rekomendācijām, un vibrācijas pārbaudi ar identifikācijas procedūru. Abas šim metodes deva līdzīgus iegūtos rezultātu. Stiprības īpašības tika noteiktas tikai ar statiskam pārbaudēm
Control of Heating Processes in Transport Mechatronic System Using Sigmoidal Neural Network
No full textIn this article interest is concentrated on the climate parameters optimization in passengers’ interior of mechatronic systems (public electric transportation vehicles- train, tram or trolleybus). Idea is to use feed forward artificial neural
network to create an algorithm and coordination mechanism for heating system parameters control to save electrical energy,
and to increase the level of comfort for passengers. A special interest for investigations and further development is devoted
to intelligent HVAC system allowing more flexible control of the system’s compressor, fan and heater operation,
and, therefore, improvement of efficiency and energy saving. This paper provides the mathematical model and algorithm
for optimal control of the climate control system
Usage Algorithm of AI Methods in Control of Railway Passengers Coach Environment Parameters
No full textThe main idea of this paper is to use methods of AI (artificial intellect) to create an algorithm and coordination mechanism for climate parameters control in the railway passengers’ coach to save an electrical energy and keep a high comfort level in the object. The article presents mathematical problem using intelligent control of HVAC systems for climate parameters optimal control. The methods of the problem solving and the structure of problem solving algorithm are given in the article. The elaborated control system model can be used for sustaining a microclimate in the different facilities, buildings and public electric transport. There are main conclusions at the end of the article
Izglītības sistēmas globalizācija un komercializācija
No full textMūsdienās izglītības sistēma aizvien vairāk tiek ierauta komercializācijas un globalizācijas procesā. Šie procesi ir savstarpēji saistīti. Šobrīd augstskolās ir jaukta tipa finansējums: valsts finansētās mācību iestādes un privātā, tostarp aizvien pieaug to augstskolu skaits kuras finansē valsts, paši studenti un sponsori). Arī Latvijā pēc neatkarības atgūšanas reāli funkcionē šāda sistēma, kuras tiesiskie, finansiālie un citi aspekti nav līdz galam sakārtoti
Prefabricated and Cast-in-Place Thermo-blocks for External Walls
No full textCast in place thermo-blocks were elaborated and were analyzed. Mechanical and thermal properties were appreciated and numerically simulated