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Enhanced air-coupled impact echo technique by phase analysis of signals from multiple sensors

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 297-310页

作者： Najjiya Almallah nenad Gucunski New Jersey Department of Transportation New Jersey 08625USA Department of Civil&Environmental Engineering Rutgers University-New BrunswickNJ 08854USA

This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from *** proposed technique takes advantage of the fact that the IE compression wave is not a propagating wave,but it is the 1st order symmetrical(S1)mode Lamb wave at zero group velocity(S1-ZGV).Therefore,it searches the phase spectra of the data collected by multiple sensors to locate the frequency corresponding to the lowest phase *** a result,the technique reduces the effect of propagating waves,including the direct acoustic wave and ambient *** is named the Constant Phase IE(CPIE).The performance of the CPIE is experimentally compared with the regular amplitude spectrum-based IE technique and two other multisensor IE *** CPIE shows a performance advantage,especially in a noisy environment.

关键词： nondestructive testing(NDT) nondestructive evaluation(NDE) bridge inspection bridge evaluation impact echo bridge delamination concrete bridge deck air-coupled sensing MEMS

Numerical algorithm for rigid body position estimation using the quaternion approach

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Acta Mechanica Sinica 2018年第2期34卷 400-408页

作者： Miodrag Zigic nenad Grahovac Department of Mechanics Faculty of Technical SciencesUniversity of Novi Sad

This paper deals with rigid body attitude estimation on the basis of the data obtained from an inertial measurement unit mounted on the body. The aim of this work is to present the numerical algorithm, which can be easily applied to the wide class of problems concerning rigid body positioning, arising in aerospace and marine engineering, or in increasingly popular robotic systems and unmanned aerial vehicles. Following the considerations of kinematics of rigid bodies, the relations between accelerations of different points of the body are given. A rotation matrix is formed using the quaternion approach to avoid singularities. We present numerical procedures for determination of the absolute accelerations of the center of mass and of an arbitrary point of the body expressed in the inertial reference frame, as well as its attitude. An application of the algorithm to the example of a heavy symmetrical gyroscope is presented, where input data for the numerical procedure are obtained from the solution of differential equations of motion, instead of using sensor measurements.

关键词： Rigid body Kinematics Inertial measurement unit Euler parameters Quaternion

Estimation of Stability Constants of Copper（Ⅱ） Complexes with a-Amino Acids Using Connectivity Index 3xV, Common Model for the Binary and Ternary Complexes

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Chinese Journal of Chemistry 2011年第9期29卷 1800-1804页

作者： Milicevic, Ante Raos, nenad Institute for Medical Research and Occupational Health Ksaverska c. 2 P. O. Box 291 HR-I O001 Zagreb Croatia

Models for estimation of the first （K1）, second （K2）, and overall stability constant （β2） of copper（II） chelates with naturally occurring amino acids, based on the valence connectivity index of the 3rd order （3Xr）, were improved by introduction of a square term and a new graph representation for mono-complexes （MLCor）. The models gave SE = 0.07, 0.05--0.07 and 0.05--0.08 for lg Ki, lg K2 and lg ,62 constants, respectively; models that encompass both bi- nary and ternary bis-complexes included indicator variable. We also validated our models on the test set which in- cluded two mono-, two binary and two ternary Cu（II） chelates with a-aminobutanoic acid and a-aminopentanoic acid, not included into the calibration. The absolute differences between experimental and predicted stability con- stants were in the range of 0.01--0.16.

关键词： copper(Ⅱ) chelate regression models topological indices computational chemistry molecular model-ing

Novel green technology for wastewater treatment: Geo-material/geopolymer applications for heavy metal removal from aquatic media

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International Journal of Sediment Research 2023年第1期38卷 33-48页

作者： nenad Grba Andre Baldermann Martin Dietzel Department of Chemistry Biochemistry and Environmental Protection Faculty of Sciences University of Novi Sad Institute of Applied Geosciences and NAWI Graz Geocenter Graz University of Technology

The aim of this paper is to show the concise chemico-physical adsorbent performance of water purification systems utilizing geo-(e.g., allophane, clinoptilolite, and smectite) and bio-polymer materials(e.g.,chitosan or cellulose nanocomposite materials) and to propose an optimal ground-water remediation technique. The performance of geo-materials is evaluated based on the individual sorption and immobilization capacities for various priority substances and pollutants(e.g., lead, zinc, cadmium, copper,arsenic, and others), their availability, and cost-efficient use. A systematic assessment of the sorption potential of geo-materials in comparison to other available sorbents used for the removal of harmful aqueous metal ions is made through a literature review. This paper introduces novel sustainable technologies based on natural and tailored silicate-polymerized substances(geo-materials and geopolymers),and highlights their applicability in the treatment of water and solid matter contaminated by heavy metal ions. The advantages of geo-materials and geopolymers over other commercially available sorbents used for heavy metal ion removal from solution are presented through a literature review. Benefits and current challenges of geo-materials and geopolymers applications in water processing technologies and in environmental remediation are discussed, with recognition of their performance, individual sorption and immobilization capacities, availability, and cost-efficient use. The applications described here comprise:(i) the removal of heavy metal ions from contaminated water using in-situ remediation strategies;(ii) heavy metal ion immobilization through co-precipitation with silicate binders in underground stabilization and waste solidification scenarios; and(iii) a proposal for a new geo-material/geopolymer-based solidification and stabilization technology for efficient, sustainable, and simultaneous treatment of soil/sediment and groundwater at environmental hotspots.

关键词： Geo-materials Heavy metal ions Environmental protection Water treatment Clay minerals Sustainability

Weighted Sum of Gray Gases Model Optimization for Numerical Investigations of Processes inside Pulverized Coal-Fired Furnaces

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Journal of Thermal Science 2017年第6期26卷 552-559页

作者： nenad Crnomarkovic Srdjan Belosevic Ivan Tomanovic Aleksandar Milicevic University of Belgrade Vinea Institute of Nuclear Sciences P. O. Box 522 11001 Belgrade Serbia

The effects of the number of significant figures （NSF） in the interpolation polynomial coefficients （IPCs） of the weighted sum of gray gases model （WSGM） on results of numerical investigations and WSGM optimization were investigated. The investigation was conducted using numerical simulations of the processes inside a pulverized coal-fired furnace. The radiative properties of the gas phase were determined using the simple gray gas model （SG）, two-term WSGM （W2）, and three-term WSGM （W3）. Ten sets of the IPCs with the same NSF were formcd for every weighting coefficient in both W2 and W3. The average and maximal relative difference values of the flame temperatures, wall temperatures, and wall heat fluxes were determined. The investigation showed that the results of numerical investigations were affected by the NSF unless it exceeded certain value. The increase in the NSF did not necessarily lead to WSGM optimization. The combination of the NSF （CNSF） was the necessary requirement for WSGM optimization.

关键词： Furnace Numerical simulation Significant figure Weighted sum of gray gases model Optimization

High-fidelity model to predict heat transfer enhancement for liquid film boiling on uniform micro-structured wicking surfaces

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National Science Review 2024年第6期11卷 93-95页

作者： Vishwanath Ganesan Mohammad Jalal Inanlu nenad Miljkovic Department of Mechanical Science and Engineering University of Illinois Urbana-Champaign Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign Materials Research Laboratory University of Illinois Urbana-Champaign International Institute for Carbon Neutral Energy Research (WPI-I2CNER) Kyushu University Institute for Sustainability Energy and Environment (iSEE)University of Illinois Urbana-Champaign

The field of thermal management in highpower electronic devices is a critical area of study, focusing on the efficient dissipation of heat to prevent device overheating and failure [1]. A key aspect of this field is understanding the dynamics of thin liquid film boiling, both on uniform and non-uniform micro-structured wicking surfaces, which can significantly enhance the heat transfer effectiveness[2].

关键词： structured predict micro liquid model boiling enhancement film heat high-fidelity

Geochemistry of Sediments from the Lopare Basin(Bosnia and Herzegovina):Implications for Paleoclimate,Paleosalinity,Paleoredox and Provenance

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1591-1618页

作者： AleksandraŠAJNOVIĆ nenad GRBA Franz NEUBAUER Milica KAŠANIN-GRUBIN Ksenija STOJANOVIĆ nenad PETKOVIĆ Branimir JOVANČIĆEVIĆ University of Belgrade Center of ChemistryICTMStudentski trg 12-1611000 BelgradeSerbia University of Novi Sad Faculty of SciencesDepartment of ChemistryBiochemistry and Environmental ProtectionTrg Dositeja Obradovica 321000 Novi SadSerbia Paris Lodron University of Salzburg Department of Geography and GeologyHellbrunnerstrasse 345020 SalzburgAustria University of Belgrade Faculty of ChemistryStudentski trg 12-1611000 BelgradeSerbia Rio Tinto–Rio Sava Exploration Takovska 4511000 BelgradeSerbia

A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin,Bosnia and Herzegovina.A total of 46 samples collected from two boreholes,Pot 1(depth of 193 m)and Pot 3(depth of 344 m),showed that element abundances like boron(B),lithium(Li),strontium(Sr),uranium(U),chromium(Cr),nickel(Ni),magnesium(Mg),sodium(Na)and calcium(Ca)are much higher than average than in the upper continental crust(UCC).Chemical composition indicates at least two sources:(i)Mesozoic ophiolites occurring in the north of the investigated area,and(ii)dacito-andesitic pyroclastics(Mesozoic to Cenozoic).Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake,which formed during a warm climatic period,probably during the Miocene Climatic Optimum.A brief episode of humid climate conditions resulted in the basin fillingup and deposition of felsic sediments enriched in thorium(Th).Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter(OM).The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical ***,the molecular distribution of n-alkanes as reliable climatic andδ-MTTC as paleosalinity indicators do not support this conclusion.

关键词： geochemistry provenance analysis paleoenvironmental conditions salinity/hypersalinity biomarker Lopare Basin Bosnia and Herzegovina

Target acquisition performance in the presence of JPEG image compression

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Defence Technology（防务技术） 2024年第3期33卷 30-41页

作者： Boban Bondzulic nenad Stojanovic Vladimir Lukin Sergey A.Stankevich Dimitrije Bujakovic Sergii Kryvenko University of Defence in Belgrade Military AcademyVeljka Lukica Kurjaka 3311000 BelgradeSerbia National Aerospace University Department of Information-Communication TechnologiesChkalova 1761070 KharkivUkraine National Academy of Sciences of Ukraine Scientific Centre for Aerospace Research of the EarthOles Honchar 55-b01054 KyivUkraine

This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the *** new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction *** is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is *** future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition *** values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.

关键词： JPEG compression Target acquisition performance Image quality assessment Just noticeable difference Probability of target detection Target mean searching time

Enhanced Osteogenesis of Nanosized Cobalt-substituted Hydroxyapatite

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Journal of Bionic Engineering 2015年第4期12卷 604-612页

作者： nenad Ignjatovic Zorica Aj dukovic Jelena Rajkovic Stevo Najman Dragan Mihailovic Dragan Uskokovic Centre for Fine Particles Processing and Nanotechnologies Institute of Technical Sciences of the Serbian Academy of Science and Arts Knez Mihailova 35/4 11000 Belgrade Serbia University of Nis Faculty of Medicine Department of Prosthodontics Clinic of Stomatology Nis Serbia University of Nis Department of Biology and Ecology Faculty of Science and Mathematics Nis Serbia University of Nis Faculty of Medicine Institute of Pathology Nis Serbia

Hydroxyapatite （HAp） is an extensively studied material with known biocompatible and osteoconductive properties in bone tissue reconstruction. The improvement of the osteogenetic potential of HAp has been tested through modification of its structure, by replacing Ca2＋ ions with Co2＋ ions. In our study, we comparatively analyze the osteogenetic potential of the syn- thesized HAp and Co2＋-substituted HAp （HAp/Co） designed on the nano-scale with the aim of specifically stimulating osteo- genesis in vivo. We present a quantitative study of the microscopic organization and structure of the newly formed tissue in a bone defect after 12 weeks and 24 weeks. A quantitative analysis of the calcium, magnesium and phosphorus content in the defect and its close environment was used to determine the deposition of minerals after bone reconstruction. The defect recon- structed with HAp/Co nanoparticles （Co2＋ content 12 wt%） was filled with a new tissue matrix composed of dense collagen fibers containing centers of mineralization after 24 weeks. The mineral deposition rate was also higher when the defect was reconstructed with HAp/Co than when it was filled with pttre HAp. A histological analysis confirmed that the alveolar bone, in which osteoporosis-induced defects were repaired using HAp/Co nanoparticles, was recuperated.

关键词： advanced osteogenesis cobalt-substituted hydroxyapatite nanoparticles histomorphometry