8 research outputs found
Neatsakymų vertinimas įmonių tyrimuose
No full textThere is not abstract.Šiame darbe buvo palyginti skirtingi atsakymo į apklausą tikimybių vertinimo būdai. Paprastasis persvėrimo, eksponentinis ir logistinės regresijos metodai buvo naudojami norint gauti sumų įverčius, kai į apklausą atsako ne visi į imtį išrinkti elementai. Atsakymų į apklausą lygiai panašūs į stebimus realiuose įmonių tyrimuose
Įvairiasluoksnių kvartero nuogulų šilumos perdavimo modelis ir šilumos laidumo parametrų vertinimas vertikaliais šilumos kolektoriais.
No full textThe growing need for low-energy or 'green' buildings and the commitments from the European Union are encouraging the use of renewable energy from 17% to 30% in 2030. The potential of shallow geothermal energy has not been studied by researchers because of no qualitative scientific in-situ thermal response test reference data sets. The qualitative borehole heat exchanger analysis could be performed while the hydrodynamic and thermal parameters of the rocks are determined by the laboratory experiments. The advanced particle swarm optimization algorithm is effectively applied to evaluate the thermal conductivity parameters of rocks. The heat transfer simulation was performed using different analytical g-functions. Stability conditions for the TRT experiment have been established to ensure the accuracy of the thermal parameter estimates. The uncertainty of parameters was performed to obtain the effects on stability and accuracy of thermal parameter estimates. The borehole heat transfer analysis was established for multi-layered Lithuanian Quaternary sediments, incorporating parameters of porosity, groundwater filtration and hydraulic gradient characteristic of the surrounding Visoriai area. An impact analysis was performed on the average temperature of the circulating fluid, changing the hydrodynamic parameters of the multilayer Quaternary sedimentscolumn. The thesis presents an expert analysis of TRT experimental equipment produced in Lithuania following confidentiality agreements
The Borehole Heat Transfer Model Performance Analysis in the Multilayer Quaternary Sediments and Evaluation of Thermal Parameters Using Vertical Borehole Exchangers.
No full textThe growing need for low-energy or 'green' buildings and the commitments from the European Union are encouraging the use of renewable energy from 17% to 30% in 2030. The potential of shallow geothermal energy has not been studied by researchers because of no qualitative scientific in-situ thermal response test reference data sets. The qualitative borehole heat exchanger analysis could be performed while the hydrodynamic and thermal parameters of the rocks are determined by the laboratory experiments. The advanced particle swarm optimization algorithm is effectively applied to evaluate the thermal conductivity parameters of rocks. The heat transfer simulation was performed using different analytical g-functions. Stability conditions for the TRT experiment have been established to ensure the accuracy of the thermal parameter estimates. The uncertainty of experiments parameters was performed to obtain the effects on the stability and accuracy of thermal parameter estimates. The borehole heat transfer analysis was established for multi-layered Lithuanian Quaternary sediments, incorporating parameters of porosity, groundwater filtration and hydraulic gradient characteristic of the surrounding Visoriai area. An impact analysis was performed on the average temperature of the circulating fluid, changing the hydrodynamic parameters of the multilayer quaternary sediment column. The thesis presents an expert analysis of TRT experimental equipment produced in Lithuania following confidentiality agreements
Vertikalių kolektorių šilumos modeliavimas radialinėmis bazinėmis funkcijomis: praktininis taikymas
No full textIn this work, the method of radial basis function (RBF) is used for the borehole heat exchanger transfers (BHET) problems. The RBF method is an efficient mesh free technique for the numerical solution of partial differential equations. The condition number of the system of linear equations (matrix A) is large it means that the ill-conditioning of matrix A makes the numerical solution unstable. Tikhonov regularization (TR) method are presented to solve such ill-conditioned systems. In this work, generalized cross-validation (GCV) method is carried out to determine the regularization parameter ksi for the TR method that minimizes the GCV function. The some practical results of numerical experiments are presented.
Šiame tyrime yra taikomas radialinių bazinių funkcijų metodas (RBF) vertikaliems kolektoriams, analizuojant šilumos perdavimo problematiką. RBF metodas yra ekonomiškas betinklis metodas sprendžiant diferencialines lygtis. Lygčių sistemos (matrica A) sąlyginis skaičius yra dažnai didelis, todėl matrica A metodas yra taikomas šiai problemai eliminuoti, gautas apibendrintu abipusio palyginimo metodu (GCV) gaunamas regularizacijos parametras ksi TR metodui, minimizuojant GCV funkciją. Rezultatuose pateiktos kelios rekomendacijos.
 
Indoor-Guided Navigation for People Who Are Blind: Crowdsourcing for Route Mapping and Assistance
No full textThis paper presents an approach to enhance electronic traveling aids (ETAs) for people who are blind and severely visually impaired (BSVI) using indoor orientation and guided navigation by employing social outsourcing of indoor route mapping and assistance processes. This type of approach is necessary because GPS does not work well, and infrastructural investments are absent or too costly to install for indoor navigation. Our approach proposes the prior outsourcing of vision-based recordings of indoor routes from an online network of seeing volunteers, who gather and constantly update a web cloud database of indoor routes using specialized sensory equipment and web services. Computational intelligence-based algorithms process sensory data and prepare them for BSVI usage. In this way, people who are BSVI can obtain ready-to-use access to the indoor routes database. This type of service has not previously been offered in such a setting. Specialized wearable sensory ETA equipment, depth cameras, smartphones, computer vision algorithms, tactile and audio interfaces, and computational intelligence algorithms are employed for that matter. The integration of semantic data of points of interest (such as stairs, doors, WC, entrances/exits) and evacuation schemes could make the proposed approach even more attractive to BVSI users. Presented approach crowdsources volunteers’ real-time online help for complex navigational situations using a mobile app, a live video stream from BSVI wearable cameras, and digitalized maps of buildings’ evacuation schemes
Occupancy Prediction Using Differential Evolution Online Sequential Extreme Learning Machine Model
No full textDespite increasing energy efficiency requirements, the full potential of energy efficiency is still unlocked; many buildings in the EU tend to consume more energy than predicted. Gathering data and developing models to predict occupants’ behaviour is seen as the next frontier in sustainable design. Measurements in the analysed open-space office showed accordingly 3.5 and 2.7 times lower occupancy compared to the ones given by DesignBuilder’s and EN 16798-1. This proves that proposed occupancy patterns are only suitable for typical open-space offices. The results of the previous studies and proposed occupancy prediction models have limited applications and limited accuracies. In this paper, the hybrid differential evolution online sequential extreme learning machine (DE-OSELM) model was applied for building occupants’ presence prediction in open-space office. The model was not previously applied in this area of research. It was found that prediction using experimentally gained indoor and outdoor parameters for the whole analysed period resulted in a correlation coefficient R2 = 0.72. The best correlation was found with indoor CO2 concentration—R2 = 0.71 for the analysed period. It was concluded that a 4 week measurement period was sufficient for the prediction of the building’s occupancy and that DE-OSELM is a fast and reliable model suitable for this purpose.This article belongs to the Section Sustainable EnergyThis research was funded by a grant (No. S-MIP-20-62) from the Research Council of Lithuania
Estimation of the vertical borehole thermal parameters based on the evolution algorithm using temperature response functions
No full textThe vertical borehole ground heat exchange performance is still the issue for the engineers installing vertical borehole ground plants using ground-coupled heat pumps. Besides geological and climate change challenges, they face the extraordinary heat transfer process between the circulating fluid and the ground surrounding the U-tube and interactions of vertical boreholes. This paper describes the technique to evaluate the grout, soil thermal parameters and borehole thermal resistance simultaneously using the particle swarm optimization algorithm. The reference thermal response data set from the sandbox laboratory was used for the analysis. A thermal response test (TRT) was made, including the different temperature response functions, for a few time scales. The estimates and errors of the grout, soil thermal conductivity and borehole resistivity were presented and compared with the results of the laboratory experiment and researchers. The target functions, in our case root mean square error values, were less than 0.034 for all analysis cases. The calculation algorithm was written using the Matlab 2016 program and could be easily expanded by increasing the number of target functions and evaluation algorithms. The presented TRT data analysis will increase the knowledge about the vertical borehole ground heat exchange design
Efficiency of Orthopaedic Brace with Laser on Knee Joint Function, Pain and Swelling
No full textBackground. The effectiveness of outpatient mobile laser intervention on specific treatment goals has not been fully explored. Thus, the aim of the study was to examine the effect of orthopaedic knee brace with laser on knee joint function, pain and swelling.Methods. Volunteers were divided into two experimental groups: chronic pain (n = 20, knee pain > 6 months) and acute pain (n = 20, knee pain < 1 week), and one control (n = 20, placebo) group. Subjects in all groups were immobilized in a knee brace for 4 weeks. In addition, the experimental groups underwent low-intensity laser therapy, whereas control group underwent pseudo-laser therapy, every second day for 10 min. The sequences of the tests were as follows: (a) clinical assessments and evaluation of knee extension and flexion amplitude, swelling, Lysholm subjective assessment questionnaire, VAS pain scale, (b) evaluation of balance using Kistler platform, (c) muscle peak torque and isometric torque variability assessment using isokinetic dynamometry. All tests were performed twice - before and after intervention.Results. Knee brace with laser is effective treatment for the reduction of pain, swelling, and recovering of daily functions (p < .05). Operation of the complex device is particularly effective in treating knee pain in the acute period (p < .05).Conclusions. Knee brace with laser therapy in the rehabilitation period ensures faster healing of patients compared to wearing only knee brace, particularly in acute pain, while muscle strength and proprioception remains depressed.Keywords: mobile laser therapy, range of motion, swelling, muscle strength, proprioception
