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A Low-Power 10-bit 72 MS/s Continuous Successive-Approximation Analog-to-Digital Converter
No full textThis paper proposess a Low-Power 10-bit 72 MS/s Successive Approximation Analog-to-Digital Converter (SAR ADC), implemented using TSMC 40 nm CMOS technology. The proposed design possesses an innovative dynamic adjustment SAR logic circuit to reduce the conversion power consumption and shorten the conversion time such that smapling rate is up to 72 MS/s. Additionally, a novel high-density and low noise unit capacitor structure is utilized to replace traditional MOM and MIM capacitors. This new capacitor architecture with extremely low unit capacitance could further reduce the power consumption during capacitor switching period. According to the simulation results, the proposed architecture achieves a 10-bit resolution, with a maximum DNL of 0.817 LSB and a maximum INL of 0.895 LSB. The SNDR is simulated to be 58.904 dB and 53.39 dB with the input frequenct at 7.19 MHz and 35.84 MHz, respectively.National Science and Techonology CouncilTSRI (Taiwan Semiconductor Research Institute) of NARL (National Applied Research Laboratories)Taip / YesMOST 109-2221-E-110-079-MOST 111- 2221-E-110-016-NSTC 113-2923-E-110-00
Gravitacijos duomenų suderinimas Rytinėje Baltijos jūroje
No full textMarine gravity datasets covering areas of state scale typically consist of data surveyed over multiple campaigns.
These campaigns often take place many years apart and are of varying resolution and accuracy. Ship-borne
campaigns are much more expensive and time-consuming than the ones on land; because of this, there is added value
in validating and possibly correcting older data sets. Throughout the recent BalMarGrav marine gravity project, dense,
high-quality gravity data covered most of the Latvian exclusive economic zone. The new data have been compared to
campaigns, both as a means of new data validation and to check for possible biases among older data sets. This research
aims to further the effort, provide more exhaustive coverage of old marine gravity points, test automated gravity point
digitisation, and perform inter-campaign comparisons, using new, filtered and more precise data. Data recovered during
this research covers the previous data gaps between sets used in previous research. Using a more complete data coverage
can improve new campaign data set validation and provide insights on inter-campaign biases within older data.
The recovered data cover shallow coastal areas, where gravity mapping was not done over the BalMarGrav project.
Thus, by applying correctional values, geoid errors can be minimised in the problematic transition zone between terrestrial
and marine data. Survey reports containing 20th-century marine gravity point data were digitised using optical
character recognition. Gravity point values were transferred to the sea surface and transformed to modern reference
frames. Modern and historic marine gravity data were filtered for gross errors and bias tracks. Data set robustness was
checked using leave-one-out cross-validation. After processing, a comparison was made between old and new data.
Results present re-processed and filtered marine gravity datasets, and their comparison statistics. Comparison statistics
before and after filtering reveal the data’s increased accuracy and precision. Mean comparison values reveal intercampaign
biases and provide correction values, which can increase data accuracy for use as input in future research
and surface modelling.Jūrų gravitacijos duomenų rinkinius, apimančius
valstybinio masto teritorijas, paprastai sudaro kelių kampanijų
metu surinkti duomenys. Šios kampanijos nevyksta dažnai, o
jų raiška ir tikslumas skiriasi. Taip yra dėl to, kad jūrinių kampanijų
vykdymas yra daug brangesnis ir užtrunka ilgiau nei
sausumos; todėl senesnių duomenų patvirtinimas ir korekcija
turi pridėtinę vertę. 2023 m. vykdant jūrinės gravitacijos projektą
„BalMarGrav“, buvo ištirta Latvijos išskirtinės ekonominės
zonos dalis ir surinkti aukštos kokybės, tankūs gravitacijos
duomenys. Jie buvo lyginami su ankstesnėmis kampanijomis
siekiant tiek patvirtinti naujuosius matavimus, tiek įvertinti
senesnių rinkinių paklaidas. Nauji duomenys padengė anksčiau
neapimtus regionus, ypač pakrančių zonoje, kur trūko
tikslių matavimų. Tai leido sumažinti geoido modelio paklaidas
probleminėje pereinamojoje zonoje tarp sausumos ir jūros
duomenų. Tyrimų ataskaitos, kuriose pateikiami XX a. jūrų
gravitacijos taškų duomenys, buvo suskaitmenintos naudojant
optinį simbolių atpažinimą, jų vertės buvo perkeltos į dabartinius
ataskaitos rėmus, o rinkinio patikimumas patikrintas
taikant Leave-one-out Cross Validation metodą. Palyginus senus
ir naujus duomenis nustatytos paklaidas tarp kampanijų,
o atliktos korekcijos pagerino geoido modeliavimo tikslumą
seklioje zonoje, kurioje tradiciškai trūksta aukštos kokybės
duomenų.Taip / Ye
Current trends and future perspectives of the Lithuanian national geodetic vertical network
No full textStraipsnyje nagrinėjamas Lietuvos valstybinis geodezinis vertikalusis tinklas, jo svarba bei atitikimas šiuolaikiniams
poreikiams. Siekiant užtikrinti tinklo duomenų tikslumą ir patikimumą aptariami dabartiniai techniniai
reikalavimai, kuriuos tinklas turi atitikti. Remiantis 5-ojo poligono pakartotiniais matavimais, įvertinta Lietuvos pirmosios
klasės vertikaliojo tinklo dabartinė būklė ir raidos tendencijos. Apžvelgiama tinklo raidos istorija, esama būklė,
pokyčiai, apribojimai ir problemos, su kuriomis susiduriama. Galiausiai, aptariamos valstybinių vertikaliųjų tinklų
ateities perspektyvos, galimos tendencijos, grėsmės ir siūlomi problemų sprendimai. Straipsnis baigiamas išvadomis ir
pasiūlymais, kaip užtikrinti tinklo patikimumą ir ilgaamžiškumą ateityje.The article discusses the condition of the Lithuanian
National Geodetic Vertical Network. It reviews the history
of the vertical network’s establishment and contemporary
needs. The article examines the technical regulation GKTR
2.12.01:2001, which outlines the requirements to ensure network
quality. The analysis uses data from the first geodetic
network’s establishment between 1998 and 2008 and data
from the 2023 renewal of the vertical network’s 5th polygon to
assess and determine the condition of existing geodetic marks.
The study showed that the installation of geodetic marks is becoming
increasingly challenging. Also, the research revealed
that the number of destroyed geodetic marks has decreased.
More attention should be given to the technical protection of
geodetic marks and updating legal regulations to ensure the
longevity of geodetic networks.Boleslovas KrikštaponisTaip / Ye
Biblioteka informuoja, 2025 Nr. 33 (730)
No full textNaujai į Web of Science ir Scopus įtrauktų Vilnius Gedimino technikos darbuotojų publikacijų sąrašai ir kitos bibliotekos aktualijos.33 (730)202
Investigation of operating modes of a variable circuit volume heat pump in a mechanical ventilation system
No full textDisertacijoje, taikant analitinius, eksperimentinius tyrimus ir skaitinį modeliavimą, tiriamas šilumos siurblio, integruoto į mechaninio vėdinimo sistemą, termodinaminis veikimo ciklas ir jo parametrų valdymas. Siekiama ištirti, kaip, keičiant šilumos siurblio kontūro tūrį, galima pagerinti sistemos efektyvumą, esant kintančioms lauko oro sąlygoms. Pagrindinis disertacijos tikslas – sukurti valdymo priemonę, leidžiančią padidinti šilumos siurblio sezoninio veikimo efektyvumą pastato vėdinimo sistemoje.
Disertacijoje sprendžiami keli pagrindiniai uždaviniai: parengiamas analitinis termodinaminis modelis ir atliekama parametrinė analizė; sukonstruojamas eksperimentinis stendas ir atliekami skirtingų veikimo režimų tyrimai; sukuriama šilumos siurblio kontūro tūrio keitimo priemonė ir vertinamas jos poveikis sistemos parametrams bei sezoniniam efektyvumui.
Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir du priedai.
Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojami darbo tikslas ir uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pateikiamos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei apibūdinama disertacijos struktūra.
Pirmajame skyriuje pateikiama literatūros apžvalga, kuri apima šilumos siurblių taikymą vėdinimo sistemose, jų valdymo principus ir technologinius sprendimus. Remiantis apžvalga, identifikuojamos tyrimų kryptys, tikslinami disertacijos uždaviniai.
Antrajame skyriuje pateikta taikyta tyrimų metodika, eksperimentinio stendo sudarymas, atliktų bandymų eiga. Taip pat pateikiamas šilumos siurblio skaitinio modelio veikimo algoritmas ir sezoninio efektyvumo vertinimo principai.
Trečiajame skyriuje pateikti analitinių, eksperimentinių ir skaitinio modeliavimo tyrimų rezultatai. Vertinamas kontūro tūrio keitimo poveikis šilumos siurblio veikimui ir efektyvumui skirtingomis eksploatavimo sąlygomis, taip pat pateiktas palyginamasis šilumos siurblio veikimo skirtingo klimato Europos regionuose tyrimas.
Disertacijos tema paskelbtos devynios mokslinės publikacijos, iš kurių dvi – recenzuojamuose mokslo žurnaluose, turinčiuose cituojamumo rodiklį Web of Science duomenų bazėse. Disertacijos rezultatai pristatyti keturiose tarptautinėse mokslinėse konferencijose Lietuvoje ir užsienyje.The dissertation investigates the thermodynamic operating cycle and parameter control of a heat pump integrated into a mechanical ventilation system through analytical, experimental research, and numerical modelling. The research explores how variations in the heat pump circuit volume influence system efficiency under changing outdoor air conditions. The primary aim is to develop a control method to enhance the seasonal operating efficiency of a heat pump integrated into a building ventilation system.
The dissertation addresses several key objectives: developing an analytical thermodynamic model and performing parametric analysis; designing and constructing an experimental test bench, followed by experimental investigations under various operating conditions; creating a mechanism for adjusting the heat pump circuit volume and evaluating its impact on system parameters and seasonal efficiency.
The dissertation consists of an introduction, three chapters, general conclusions, references, the author’s publications on the topic, and two appendices.
The introduction discusses the research problem and relevance, describes the object of investigation, formulates the aim and specific objectives, outlines the methodology, highlights the scientific novelty and practical significance, and presents defendable statements. It concludes with an overview of the author’s publications and conference presentations related to the topic, and a description of the dissertation structure.
The First Chapter provides a literature review on heat pump applications in ventilation systems, their control principles, and technological solutions. It identifies key research directions and refines objectives.
The Second Chapter describes the research methodology, the design of the experimental setup, and the procedure for conducting the tests. Additionally, the chapter outlines the operating algorithm of the numerical heat pump model and seasonal efficiency evaluation principles.
The Third Chapter presents the results of analytical, experimental, and numerical modelling studies. It evaluates the impact of circuit volume adjustment on the performance and efficiency of the heat pump under varying operating conditions and provides a comparative analysis of heat pump operation in European regions with different climates.
Nine scientific publications related to the dissertation have been published, including two in peer-reviewed journals indexed in Web of Science with citation indices. The results have been presented at four international scientific conferences in Lithuania and abroad
Advanced Deep Learning Approaches for Automated Diagnosis of Cardiac Arrhythmia in Multi-lead ECG Signals
No full textAtrial fibrillation (AF) is a widespread and life-threatening heart arrhythmia disorder that affects over a million persons worldwide, predominantly older adults. The exact detection of AF is important, but the complication of ECG signals leads to conventional methods based on manual interpretation. To address this challenge, in this paper a new deep learning method has been proposed that used an Bidirectional Long Short-Term Memory (BLSTM) block with the deep Convolutional Neural Network (CNN). The processed data is analyzed through a four-layer deep learning model, consisting an BLSTM block of two and two layers that are fully connected. In this project, the first step is an analysis process involves wavelet transform for ECG signal preprocessing, that removed the noise and enhanced the signal clarity. Peak extraction and segmentation preformed. Two datasets signal, one for RR interval (dataset A) and one for sequence of heartbeats in terms of waves P-QRS-T, then after the fully connected layer it detects if the signal is AF or not an AF. The model performs remarkably, DenseNet-169 + BLSTM remains the best-performing model, achieving the highest accuracy (98.75%) while maintaining a good balance between precision, sensitivity, and specificity. To the best of understanding, when compared to many other methods, the suggested technique produces great result states of filters and algorithm, this provides an advance technique for the detection of AF. These values confirm the dependability and high efficiency of proposed AF detection about current AF detection methodologies.Taip / Ye
PET Neuroimaging Enhancements for Improved Mild Cognitive Impairment Detection
No full textMild Cognitive Impairment (MCI) is a neurode-generative condition characterized by cognitive decline that may progress to Alzheimer’s disease. Modern neuroimaging techniques, particularly Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET), serve as essential diagnostic tools by providing detailed structural and metabolic information of the brain tissue. Fluorodeoxyglucose PET (FDG-PET) has emerged as one of the most sensitive early indicators of MCI due to its ability to quantify glucose metabolism in specific regions of the brain. Patients with MCI exhibit characteristic patterns of reduced metabolic activity in distinct brain regions, which can be detected through automated analysis.Recent advances in Artificial Intelligence (AI) and Deep Learning (DL) have revolutionized medical image analysis through their superior pattern recognition capabilities. State-of-the-art (SOTA) image classification methods, including Convolutional Neural Networks (CNN) and Vision Transformers (ViT), demonstrate remarkable precision in distinguishing MCI patients from Cognitively Normal (CN) individuals. This study presents a novel methodology that uses FDG-PET as the primary diagnostic modality, incorporating histogram equalization technique, noise reduction and advanced augmentation pipeline. When combined with SOTA image classifiers, our approach achieves a 7% improvement in diagnostic accuracy over the baseline, highlighting how neuroimaging enhancement techniques can improve the already robust diagnostic capabilities of DL image classifiers.Taip / Ye
Biblioteka informuoja, 2025 Nr. 11 (708)
No full textNaujai į Web of Science ir Scopus įtrauktų Vilnius Gedimino technikos darbuotojų publikacijų sąrašai ir kitos bibliotekos aktualijos.11 (708)202
HYPHA-4.0: biostruktūrų meninio tyrimo katalogas
No full textHifas – hypha (gr. ὑφή, hyphē) - „tinklas“ - išsišakojusi, susiraizgiusi ir tankiai susipynusi gijelė. Daugybė plonyčių hifų sudaro grybieną - micelį.
Architektūros plotmėje nedaug nagrinėta grybienos materija yra labai išplitusi gamtoje ir užima svarbią vietą ekosistemoje.
Meninio tyrimo tikslas – praplėsti architektūrinę raišką.
Tyrimu norima pažvelgti į netikėtą ir mažai pažintą grybų kuriamą erdvinį pasaulį, kuris gali praplėsti vaizduotės bei kūrybiškumo ribas.Lietuvos Kultūros Taryb
Implementing Holacracy principles for increased efficiency in non-governmental organizations in Latvia
No full textThe aim of this paper is to evaluate organizations that operate according to Holacracy principles, their potential
benefits and challenges of its implementation, particularly in non-governmental organizations (NGOs). This paper
offers a novel perspective on modernizing NGO management practices with Holacracy approach. NGOs are usually
complex and dynamic in structure, therefore their “hard to manage” platform is an excellent to analyze contemporary
management opportunities. The results of the paper indicate that the ability to adapt to modern changing conditions is
a significant advantage for NGO organizations and a good example for other organizations, structured meetings could
be mentioned as one of the key benefits. The research will address all key questions and provide conclusions and recommendations
that can support NGOs in implementing Holacracy.Taip / Ye