Performance supported by competencies is very important for every organization.Employees play the key role in the achieving of the performance.Organizations are aware of the importance of improving competencies of its...Performance supported by competencies is very important for every organization.Employees play the key role in the achieving of the performance.Organizations are aware of the importance of improving competencies of its employees.They develop them by organizing training courses.Modern trends in human resources management progressively press for more and more complex assessment of employees based on the networking performance model with the competency model.Nor is it otherwise in the field of higher education.Universities evolve pressure to increase especially the scientific performance.Therefore it is necessary to develop the teacher’s competences.The goal of this article is to create a competency model of the teacher at the department by using multi-criteria decision making method—analytic hierarchy process(AHP)—to determine the weight of individual competencies represented in this model.The competency model can play an important role in evaluating the work of employees and significantly contribute to the objectification of rewarding system and human resources management at the department.展开更多
Computer vision(CV)was developed for computers and other systems to act or make recommendations based on visual inputs,such as digital photos,movies,and other media.Deep learning(DL)methods are more successful than ot...Computer vision(CV)was developed for computers and other systems to act or make recommendations based on visual inputs,such as digital photos,movies,and other media.Deep learning(DL)methods are more successful than other traditional machine learning(ML)methods inCV.DL techniques can produce state-of-the-art results for difficult CV problems like picture categorization,object detection,and face recognition.In this review,a structured discussion on the history,methods,and applications of DL methods to CV problems is presented.The sector-wise presentation of applications in this papermay be particularly useful for researchers in niche fields who have limited or introductory knowledge of DL methods and CV.This review will provide readers with context and examples of how these techniques can be applied to specific areas.A curated list of popular datasets and a brief description of them are also included for the benefit of readers.展开更多
Initiatives to minimise battery use,address sustainability,and reduce regular maintenance have driven the challenge to use alternative power sources to supply energy to devices deployed in Internet of Things(IoT)netwo...Initiatives to minimise battery use,address sustainability,and reduce regular maintenance have driven the challenge to use alternative power sources to supply energy to devices deployed in Internet of Things(IoT)networks.As a key pillar of fifth generation(5G)and beyond 5G networks,IoT is estimated to reach 42 billion devices by the year 2025.Thermoelectric generators(TEGs)are solid state energy harvesters which reliably and renewably convert thermal energy into electrical energy.These devices are able to recover lost thermal energy,produce energy in extreme environments,generate electric power in remote areas,and power micro‐sensors.Applying the state of the art,the authorspresent a comprehensive review of machine learning(ML)approaches applied in combination with TEG‐powered IoT devices to manage and predict available energy.The application areas of TEG‐driven IoT devices that exploit as a heat source the temperature differences found in the environment,biological structures,machines,and other technologies are summarised.Based on detailed research of the state of the art in TEG‐powered devices,the authors investigated the research challenges,applied algorithms and application areas of this technology.The aims of the research were to devise new energy prediction and energy management systems based on ML methods,create supervised algorithms which better estimate incoming energy,and develop unsupervised and semi‐supervised ap-proaches which provide adaptive and dynamic operation.The review results indicate that TEGs are a suitable energy harvesting technology for low‐power applications through their scalability,usability in ubiquitous temperature difference scenarios,and long oper-ating lifetime.However,TEGs also have low energy efficiency(around 10%)and require a relatively constant heat source.展开更多
To improve the pozzolanic reactivity,waste glass(WG)needs to be micronized to fine particles so as to expedite the leaching of active constituent.The key feature of this work is to examine the effect of wet-grinded WG...To improve the pozzolanic reactivity,waste glass(WG)needs to be micronized to fine particles so as to expedite the leaching of active constituent.The key feature of this work is to examine the effect of wet-grinded WG on the mechanical and structural properties of cement based materials.The experimental results show that wet-grinding can improve the ions leaching behavior of WGP and decrease the stability of silicon oxide bond.The pozzolanic reactivity of WGP was dramatically enhanced after wet-grinding,as high as 144.1%at 1 d and 110.9%at 28 d when the mean grain size of WGP reached 0.90μm.The ground WGP can promote the transformation of capillary pores to gel pores to improve the compactness of microstructure regardless of the reaction time.展开更多
With the ever growth of Internet users,video applications,and massive data traffic across the network,there is a higher need for reliable bandwidth-efficient multimedia communication.Versatile Video Coding(VVC/H.266)i...With the ever growth of Internet users,video applications,and massive data traffic across the network,there is a higher need for reliable bandwidth-efficient multimedia communication.Versatile Video Coding(VVC/H.266)is finalized in September 2020 providing significantly greater compression efficiency compared to Highest Efficient Video Coding(HEVC)while providing versatile effective use for Ultra-High Definition(HD)videos.This article analyzes the quality performance of convolutional codes,turbo codes and self-concatenated convolutional(SCC)codes based on performance metrics for reliable future video communication.The advent of turbo codes was a significant achievement ever in the era of wireless communication approaching nearly the Shannon limit.Turbo codes are operated by the deployment of an interleaver between two Recursive Systematic Convolutional(RSC)encoders in a parallel fashion.Constituent RSC encoders may be operating on the same or different architectures and code rates.The proposed work utilizes the latest source compression standards H.266 and H.265 encoded standards and Sphere Packing modulation aided differential Space Time Spreading(SP-DSTS)for video transmission in order to provide bandwidth-efficient wireless video communication.Moreover,simulation results show that turbo codes defeat convolutional codes with an averaged E_(b)/N_(0) gain of 1.5 dB while convolutional codes outperformcompared to SCC codes with an E_(b)/N_(0) gain of 3.5 dBatBit ErrorRate(BER)of 10−4.The Peak Signal to Noise Ratio(PSNR)results of convolutional codes with the latest source coding standard of H.266 is plotted against convolutional codes with H.265 and it was concluded H.266 outperform with about 6 dB PSNR gain at E_(b)/N_(0) value of 4.5 dB.展开更多
On the basis of the solution of the space-time characteristic system by the method of geometric optics using symbolic calculations,analytical and numerical simulation of the propagation of the ordinary and extraordina...On the basis of the solution of the space-time characteristic system by the method of geometric optics using symbolic calculations,analytical and numerical simulation of the propagation of the ordinary and extraordinary radio waves in the conducting equatorial ionospheric plasma was made considering the anisotropy of plasma irregularities and non-stationary nature of propagation medium.Broadening of the spectrum and the displacement of its maximum contain velocity of a turbulent plasma flow and parameters characterizing anisotropic plasmonic structures.Statistical moments of both radio waves do not depend on the absorption sign and are valid for both active and absorptive random media.Temporal pulsations and conductivity of a turbulent ionospheric plasma have an influence on the evaluation of the spectrum-varying propagation distances travelling by these waves.The new double-humped effect in the temporal spectrum has been revealed for the ordinary wave varying anisotropy coefficient and dip angle of stretched plasmonic structures.From a theoretical point of view,the algorithms developed in this work allow effective modelling of the propagation of both radio signals in the equatorial conductive ionospheric plasma,considering the external magnetic field,inhomogeneities of electron density in-homogeneities,as well as non-stationary.展开更多
As a new type of green energy, lithium-ion battery(LIB) has been widely used in various electric portable devices because of its high-voltage, large specific capacity, long cycle life and environmental friendliness [1...As a new type of green energy, lithium-ion battery(LIB) has been widely used in various electric portable devices because of its high-voltage, large specific capacity, long cycle life and environmental friendliness [1,2]. However, today’s anode materials of commercial LIBs cannot meet the further development requirements of smart devices and electric car due to the limitations of the electrode capacity(e.g. 372 mAh g-1 for graphite).展开更多
Lithium metal batteries(LMBs)of an ultrahigh theoretical energy density have attracted lots of attentions for a wide range of practical applications.However,there are still numerous challenges in LMBs system,such as p...Lithium metal batteries(LMBs)of an ultrahigh theoretical energy density have attracted lots of attentions for a wide range of practical applications.However,there are still numerous challenges in LMBs system,such as poor cycling performance,complicated interfacial reactions,low Coulombic efficiency,and uncontrollable lithium dendrites.Understanding Li^+ions’nucleation mechanism is essential to tackle the uncontrolled growth of lithium dendrites.However,the nucleation behavior of Li+ions is interfered by the structural complexities of existing substrates during the reduplicative plating/stripping process and the rational mechanism of uniform nucleation of Li^+ions has not been clearly understood from the theoretical point of view.In our work,first-principles theoretical calculations are carried out to investigate the Li^+ions nucleation performance on metal-doped Cu surfaces(MDCSs)and the key descriptors that determines the properties of various MDCSs are systematically summarized.It is found that the introduction of heterogeneous doping Ag and Zn atoms will induce a gradient adsorption energy on MDCSs,and such gradient deposition sites can reduce the diffusion barriers and accelerate the diffusion rates of Li+ions dynamically.By maneuvering the Li+ions nucleation on MDCSs,a dendrite-free lithium metal anode can be achieved without the use of porous matrixes and complex synthesis process,which can be attributed to suppress the uncontrollable lithium dendrites for realizing the high-efficiency LMBs.展开更多
Aqueous colloidal dispersions containing Znx Cd1‐x S quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide,in the presence of a cetyltrimethylamm...Aqueous colloidal dispersions containing Znx Cd1‐x S quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide,in the presence of a cetyltrimethylammonium bromide stabilizer.Ultraviolet‐visible absorption spectroscopy was used to determine the transition energies of the QDs,which in turn were used to calculate their sizes,which depended on their composition.The QD size decreased with increasing Zn content.The photocatalytic activity of the Znx Cd1‐x S QDs was studied by the decomposition of methylene blue under ultraviolet irradiation,at a maximum intensity at 365 nm (3.4 e V).Three different photo‐catalytic activity regions were observed,which depended on the Zn content.The quantum levels of the QDs could be excited by incident irradiation,and influenced the resulting photocatalytic activity.Maximum photocatalytic activity was achieved at x = 0.6,where the QD transition energy was equal to the irradiation photon energy.The photocatalytic efficiency of the QDs depended on their surface area and arrangement of quantum levels,because of the quantum size effect.展开更多
Detecting COVID-19 cases as early as possible became a critical issue that must be addressed to avoid the pandemic’s additional spread and early provide the appropriate treatment to the affected patients.This study a...Detecting COVID-19 cases as early as possible became a critical issue that must be addressed to avoid the pandemic’s additional spread and early provide the appropriate treatment to the affected patients.This study aimed to develop a COVID-19 diagnosis and prediction(AIMDP)model that could identify patients with COVID-19 and distinguish it from other viral pneumonia signs detected in chest computed tomography(CT)scans.The proposed system uses convolutional neural networks(CNNs)as a deep learning technology to process hundreds of CT chest scan images and speeds up COVID-19 case prediction to facilitate its containment.We employed the whale optimization algorithm(WOA)to select the most relevant patient signs.A set of experiments validated AIMDP performance.It demonstrated the superiority of AIMDP in terms of the area under the curve-receiver operating characteristic(AUC-ROC)curve,positive predictive value(PPV),negative predictive rate(NPR)and negative predictive value(NPV).AIMDP was applied to a dataset of hundreds of real data and CT images,and it was found to achieve 96%AUC for diagnosing COVID-19 and 98%for overall accuracy.The results showed the promising performance of AIMDP for diagnosing COVID-19 when compared to other recent diagnosing and predicting models.展开更多
This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards.This composite material is made of gypsum a...This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards.This composite material is made of gypsum and reinforcing natural fibers.The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum.From this composite material,high-strength plasterboards could then be produced,which meet the higher demands of users than conventional gypsum plasterboards.For their production,natural waste materials would be used efficiently.As part of the development of new building materials,it is necessary to specify essential characteristics for their later use in civil engineering.Crushed wheat straw and three gypsum classes with strengths G2(2 MPa)—gypsum Class I.,G5(5 MPa)—gypsum Class II.and G16(16 MPa)—gypsum Class III.were used to create the test samples.Samples were made with different ratios of the two ingredients,with the percentages of straw being 0%,2.5%,and 5%for each gypsum grade.The first part of the article describes how the increasing proportion of straw affects the composite’s mechanical properties(flexural strength and compressive strength).The second part of the article focuses on the change of thermal properties(thermal conductivity and specific heat capacity).The last part of the article mentions the verification of the fire properties(single-flame source fire test and gross heat of combustion)of this composite material.The research has shown that the increasing proportion of straw reinforcement caused a deterioration in the flexural strength(up to 56.49%in the 3.series of gypsum Class II.)and compressive strength(up to 80.27%in the 3.series of gypsum Class III.)and an improvement in the specific heat capacity and thermal conductivity(up to 31.40%in the 3.series).This composite material is thus not suitable for the production of high-strength plasterboards,but its reduced mechanical properties do not prevent its use for interior plasters.Based on the performed fire tests,it can be said that this composite material can be classified as a non-flammable material of reaction to fire Classes A1 or A2.From an ecological point of view,it is advantageous to use a composite material with a higher straw content.展开更多
In this paper, the system performance of a decode-and-forward(DF) full-duplex(FD) adaptive relaying network over the Rician fading environment is proposed, analyzed and demonstrated. In the first stage, the system is ...In this paper, the system performance of a decode-and-forward(DF) full-duplex(FD) adaptive relaying network over the Rician fading environment is proposed, analyzed and demonstrated. In the first stage, the system is presented with the energy harvesting and information transmission processes. After that, the analytical expressions of the achievable throughput, the outage probability, and symbol error ratio(SER) were proposed, analyzed and demonstrated. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions in the influence of the key system parameters. The results show that the analytical and simulated results match for all possible parameter values.展开更多
The paper describes an analysis of thermo-mechanical (TM) processes appearing during the Aspo Pillar Stability Experiment (APSE). This analysis is based on finite elements with elasticity, plasticity and dam- age ...The paper describes an analysis of thermo-mechanical (TM) processes appearing during the Aspo Pillar Stability Experiment (APSE). This analysis is based on finite elements with elasticity, plasticity and dam- age mechanics models of rock behaviour and some least squares calibration techniques. The main aim is to examine the capability of continuous mechanics models to predict brittle damage behaviour of gran- ite rocks. The performed simulations use an in-house finite element software GEM and self-developed experimental continuum damage MATLAB code. The main contributions are twofold. First, it is an inverse analysis, which is used for (1) verification of an initial stress measurement by back analysis of conver- gence measurement during construction of the access tunnel and (2) identification of heat transfer rock mass properties by an inverse method based on the known heat sources and temperature measurements. Second, three different hierarchically built models are used to estimate the pillar damage zones, i.e. elas- tic model with Drucker-Prager strength criterion, elasto-plastic model with the same yield limit and a combination of elasto-plasticity with continuum damage mechanics. The damage mechanics model is also used to simulate uniaxial and triaxial compressive strength tests on the ,Aspo granite.展开更多
This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaskanear Banska Bystrica in Slovakia.The aim of the study is to demonstrate the impossibility ...This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaskanear Banska Bystrica in Slovakia.The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material.Its maximum thickness is 3 m.Another specificific condition of the study area is its location in the built-up area,due to which the applicability of geophysical methods was limited.The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill,which complicates the identification of cave spaces.The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.展开更多
Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive fie...Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive field and expected energy density product of a magnet made from a novel magnetic material composition.Iron(Fe)-rich magnetic phases suitable for permanent magnets can be found by means of adaptive genetic algorithms.The intrinsic properties computed by ab initio simulations are used as input for micromagnetic simulations of the hysteresis properties of permanent magnets with a realistic structure.Using machine learning techniques,the magnet’s structure can be optimized so that the upper limits for coercivity and energy density product for a given phase can be estimated.Structure property relations of synthetic permanent magnets were computed for several candidate hard magnetic phases.The following pairs(coercive field(T),energy density product(kJ·m^-3))were obtained for iron-tin-antimony(Fe3Sn0.75Sb0.25):(0.49,290),L10-ordered iron-nickel(L10 FeNi):(1,400),cobalt-iron-tantalum(CoFe6Ta):(0.87,425),and manganese-aluminum(MnAl):(0.53,80).展开更多
AIM:To assess the role of orthoptics in referring patients with orbital floor blowout fracture(OFBF)for conservative or surgical treatment and based on the results,to propose a scoring system for such decision making....AIM:To assess the role of orthoptics in referring patients with orbital floor blowout fracture(OFBF)for conservative or surgical treatment and based on the results,to propose a scoring system for such decision making.METHODS:A retrospective analysis of 69 patients with OFBF was performed(35 treated conservatively,34 surgically).The role of orthoptics in referring to surgery or conservative treatment was retrospectively evaluated,the factors with the highest significance for decision making were identified,and a scoring system proposed using Logistic regression.RESULTS:According to defined criteria,the treatment was unsuccessful in 2(6%)surgically treated and only in one(3%)conservatively treated patient.The proposed scoring system includes the defect size and several values resulting from the orthoptic examination,the elevation of the eyebulb measured on Lancaster screen being the most significant.CONCLUSION:The study demonstrates the benefits of orthoptic examination when making decisions on conservative or surgical treatment and for diagnosing ocular motility disorder(with or without binocular diplopia)in OFBF patients.The proposed scoring system could,following verification in a prospective study,become a valuable adjunctive tool.展开更多
The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content(from 47.4 percent up to 82 percent),to com...The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content(from 47.4 percent up to 82 percent),to compare and to analyze the potential use of the recycled fibers for building application,such as plastering mortar.Changes in the chemical composition,cellulose crystallinity and degree of polymerization of the fibers were found.The recycled fibers of lower quality showed heterogeneity in the fiber sizes(width and length),and they had greater surface roughness in comparison to high purity wood pulp samples.The high purity fibers(cellulose content>80.0 percent)had greater crystallinity and more homogeneous and smooth surfaces than the recycled fibers.The presence of calcite and kaolinite in all of the recycled cellulosic fibers samples was confirmed,whereas only one wood pulp sample contained calcite.The influence of the chemical composition was reflected in the fiber density values.Changes in the chemical composition and cellulose structure of the fibers affected the specific surface area,porosity and thermo physical properties of the fibers.More favorable values of thermal conductivity were reached for the recycled fibers than for the wood pulp samples.Testing the suitability of the recycled fibers with inorganic impurities originating from the paper-making processes for their use as fillers in plastering mortars(0.5 wt.%fiber content of the total weight of the filler and binder)confirmed their application by achieving a compressive strength value of 28 day-cured fiber-cement mortar required by the standard as well as by measured more favorable value of capillary water absorption coefficient.展开更多
Among various anode candidates for potassium-ion batteries,carbonaceous materials have attracted significant attention due to their overwhelming advantages including cost-effectiveness and environmental benignity.Howe...Among various anode candidates for potassium-ion batteries,carbonaceous materials have attracted significant attention due to their overwhelming advantages including cost-effectiveness and environmental benignity.However,the inferior specific capacity and the sluggish reaction kinetics hinder the further development in this realm.Herein,we report biomass templated synthesis of boron/oxygen heteroatom co-doped carbon particles(BO-CPs)via direct plasma-enhanced chemical vapor deposition.With the combined advantages of abundant active sites,large accessible surface area,and functional groups,BO-CP anode exhibits high reversible specific capacity(426.5 mAh g^(-1)at 0.1 A g^(-1))and excellent rate performance(166.5 mAh g^(-1)at 5 A g^(-1)).The K-ion storage mechanism is probed by operando Raman spectroscopy,ex situ X-ray photoelectron spectroscopy/electrochemical impedance spectroscopy,galvanostatic intermittent titration technique measurements,and theoretical simulations.The synergistic effect of boron and oxygen co-doping greatly facilitates the performance of carbon-based anode,wherein boron dopant improves the conductivity of carbon framework and the oxygen dopant affords ample active sites and thus harvests additional specific capacity.This work is anticipated to propel the development of high-performance anode materials for emerging energy storage devices.展开更多
The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes, especially including appropriate land-use planning. However, t...The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes, especially including appropriate land-use planning. However, the relationship between relevant geological information and the geological environment is vital for foundation engineering purposes, especially where demanding structures are involved. This information is most conveniently structured when accumulated information concerning engineering-geological zones is utilized. This necessarily includes knowledge of rock workability and also of the pre-Quaternary bedrock, and these characteristics were then related to the current built-up area and future development according to the land-use plans in a case study are from the Petrvald Region (Czech Republic). The geological environment of area has been severely influenced by anthropogenic effects of deep black coal mining. Results of this research showed that future development should be founded on spoil banks, dumps, and settling basins. According to the land-use plan, this zone occupies 44.9% of the area of interest, and its materials predominantly emanate from mining in the Ostrava-Karvina Coal District. For future foundation structures planned there, it is imperative to consult detailed engineering-geological study. However, attention to and reliance on this necessity is not reflected in the existing land-use plan.展开更多
基金supported within Operational Programme Education for Competitiveness—Project No.CZ.1.07/2.3.00/20.0296.
文摘Performance supported by competencies is very important for every organization.Employees play the key role in the achieving of the performance.Organizations are aware of the importance of improving competencies of its employees.They develop them by organizing training courses.Modern trends in human resources management progressively press for more and more complex assessment of employees based on the networking performance model with the competency model.Nor is it otherwise in the field of higher education.Universities evolve pressure to increase especially the scientific performance.Therefore it is necessary to develop the teacher’s competences.The goal of this article is to create a competency model of the teacher at the department by using multi-criteria decision making method—analytic hierarchy process(AHP)—to determine the weight of individual competencies represented in this model.The competency model can play an important role in evaluating the work of employees and significantly contribute to the objectification of rewarding system and human resources management at the department.
基金supported by the Project SP2023/074 Application of Machine and Process Control Advanced Methods supported by the Ministry of Education,Youth and Sports,Czech Republic.
文摘Computer vision(CV)was developed for computers and other systems to act or make recommendations based on visual inputs,such as digital photos,movies,and other media.Deep learning(DL)methods are more successful than other traditional machine learning(ML)methods inCV.DL techniques can produce state-of-the-art results for difficult CV problems like picture categorization,object detection,and face recognition.In this review,a structured discussion on the history,methods,and applications of DL methods to CV problems is presented.The sector-wise presentation of applications in this papermay be particularly useful for researchers in niche fields who have limited or introductory knowledge of DL methods and CV.This review will provide readers with context and examples of how these techniques can be applied to specific areas.A curated list of popular datasets and a brief description of them are also included for the benefit of readers.
基金supported by the project SP2023/009“Development of algorithms and systems for control,mea-surement and safety applications IX”of the Student Grant System,VSB‐TU Ostrava.This work was also supproted by the project FW03010194“Development of a System for Monitoring and Evaluation of Selected Risk Factors of Physical Workload in the Context of Industry 4.0″of the Technology Agency of the Czech Republicfunding from the European Union's Horizon 2020 research and innovation programme under grant agreement No.856670.This research received no external funding.
文摘Initiatives to minimise battery use,address sustainability,and reduce regular maintenance have driven the challenge to use alternative power sources to supply energy to devices deployed in Internet of Things(IoT)networks.As a key pillar of fifth generation(5G)and beyond 5G networks,IoT is estimated to reach 42 billion devices by the year 2025.Thermoelectric generators(TEGs)are solid state energy harvesters which reliably and renewably convert thermal energy into electrical energy.These devices are able to recover lost thermal energy,produce energy in extreme environments,generate electric power in remote areas,and power micro‐sensors.Applying the state of the art,the authorspresent a comprehensive review of machine learning(ML)approaches applied in combination with TEG‐powered IoT devices to manage and predict available energy.The application areas of TEG‐driven IoT devices that exploit as a heat source the temperature differences found in the environment,biological structures,machines,and other technologies are summarised.Based on detailed research of the state of the art in TEG‐powered devices,the authors investigated the research challenges,applied algorithms and application areas of this technology.The aims of the research were to devise new energy prediction and energy management systems based on ML methods,create supervised algorithms which better estimate incoming energy,and develop unsupervised and semi‐supervised ap-proaches which provide adaptive and dynamic operation.The review results indicate that TEGs are a suitable energy harvesting technology for low‐power applications through their scalability,usability in ubiquitous temperature difference scenarios,and long oper-ating lifetime.However,TEGs also have low energy efficiency(around 10%)and require a relatively constant heat source.
基金Funded by the National Natural Science Foundation of China(No.52008158)the National Key Research and Development Program of China(No.2019YFC1907104)。
文摘To improve the pozzolanic reactivity,waste glass(WG)needs to be micronized to fine particles so as to expedite the leaching of active constituent.The key feature of this work is to examine the effect of wet-grinded WG on the mechanical and structural properties of cement based materials.The experimental results show that wet-grinding can improve the ions leaching behavior of WGP and decrease the stability of silicon oxide bond.The pozzolanic reactivity of WGP was dramatically enhanced after wet-grinding,as high as 144.1%at 1 d and 110.9%at 28 d when the mean grain size of WGP reached 0.90μm.The ground WGP can promote the transformation of capillary pores to gel pores to improve the compactness of microstructure regardless of the reaction time.
基金supported by the Ministry of Education of the Czech Republic(Project No.SP2022/18 and No.SP2022/5)by the European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project,project number CZ.02.1.01/0.0/0.0/16019/0000867 within the Operational Programme Research,Development,and Education.
文摘With the ever growth of Internet users,video applications,and massive data traffic across the network,there is a higher need for reliable bandwidth-efficient multimedia communication.Versatile Video Coding(VVC/H.266)is finalized in September 2020 providing significantly greater compression efficiency compared to Highest Efficient Video Coding(HEVC)while providing versatile effective use for Ultra-High Definition(HD)videos.This article analyzes the quality performance of convolutional codes,turbo codes and self-concatenated convolutional(SCC)codes based on performance metrics for reliable future video communication.The advent of turbo codes was a significant achievement ever in the era of wireless communication approaching nearly the Shannon limit.Turbo codes are operated by the deployment of an interleaver between two Recursive Systematic Convolutional(RSC)encoders in a parallel fashion.Constituent RSC encoders may be operating on the same or different architectures and code rates.The proposed work utilizes the latest source compression standards H.266 and H.265 encoded standards and Sphere Packing modulation aided differential Space Time Spreading(SP-DSTS)for video transmission in order to provide bandwidth-efficient wireless video communication.Moreover,simulation results show that turbo codes defeat convolutional codes with an averaged E_(b)/N_(0) gain of 1.5 dB while convolutional codes outperformcompared to SCC codes with an E_(b)/N_(0) gain of 3.5 dBatBit ErrorRate(BER)of 10−4.The Peak Signal to Noise Ratio(PSNR)results of convolutional codes with the latest source coding standard of H.266 is plotted against convolutional codes with H.265 and it was concluded H.266 outperform with about 6 dB PSNR gain at E_(b)/N_(0) value of 4.5 dB.
基金supported by Shota Rustaveli National Science Foundation of Georgia(SRNSFG),grant NFR-21-316“Investigation of the statistical characteristics of scattered electromagnetic waves in the terrestrial atmosphere and application”.
文摘On the basis of the solution of the space-time characteristic system by the method of geometric optics using symbolic calculations,analytical and numerical simulation of the propagation of the ordinary and extraordinary radio waves in the conducting equatorial ionospheric plasma was made considering the anisotropy of plasma irregularities and non-stationary nature of propagation medium.Broadening of the spectrum and the displacement of its maximum contain velocity of a turbulent plasma flow and parameters characterizing anisotropic plasmonic structures.Statistical moments of both radio waves do not depend on the absorption sign and are valid for both active and absorptive random media.Temporal pulsations and conductivity of a turbulent ionospheric plasma have an influence on the evaluation of the spectrum-varying propagation distances travelling by these waves.The new double-humped effect in the temporal spectrum has been revealed for the ordinary wave varying anisotropy coefficient and dip angle of stretched plasmonic structures.From a theoretical point of view,the algorithms developed in this work allow effective modelling of the propagation of both radio signals in the equatorial conductive ionospheric plasma,considering the external magnetic field,inhomogeneities of electron density in-homogeneities,as well as non-stationary.
基金supported by National Key Research and Development Program of China (No.2017YFB0702100)the National Natural Science Foundation of China (No.11404017)+4 种基金Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Human Resources and Social Security of China, Beijing Natural Science Foundation (No.20192029)supported by the European Regional Development Fund in the IT4Innovations National Supercomputing Center-Path to Exascale project, No.CZ.02.1.01/ 0.0/0.0/16_013/0001791 within the Operational Programme Research, Development and Education by the Ministry of Education, Youth, and Sport of the Czech Republicgrant No.17-27790S of the Czech Science FoundationsMobility grant No.8J18DE004 of the Ministry of Education, Youngth and Sports of the Czech RepublicSGS No.SP2019/110。
文摘As a new type of green energy, lithium-ion battery(LIB) has been widely used in various electric portable devices because of its high-voltage, large specific capacity, long cycle life and environmental friendliness [1,2]. However, today’s anode materials of commercial LIBs cannot meet the further development requirements of smart devices and electric car due to the limitations of the electrode capacity(e.g. 372 mAh g-1 for graphite).
基金supported by the National Key Research and Development Program of China(No.2017YFB0702100)the National Natural Science Foundation of China(11404017)+2 种基金the Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Human Resources and Social Security of Chinasupport by the European Regional Development Fund in the IT4Innovations national supercomputing center-Path to Exascale project,No.CZ.02.1.01/0.0/0.0/16_013/0001791 within the Operational Programme Research,Development and Educationby the Ministry of Education by the Ministry of Education,Youth,and Sport of the Czech Republic and grant No.17-27790S of the Czech Science Foundations
文摘Lithium metal batteries(LMBs)of an ultrahigh theoretical energy density have attracted lots of attentions for a wide range of practical applications.However,there are still numerous challenges in LMBs system,such as poor cycling performance,complicated interfacial reactions,low Coulombic efficiency,and uncontrollable lithium dendrites.Understanding Li^+ions’nucleation mechanism is essential to tackle the uncontrolled growth of lithium dendrites.However,the nucleation behavior of Li+ions is interfered by the structural complexities of existing substrates during the reduplicative plating/stripping process and the rational mechanism of uniform nucleation of Li^+ions has not been clearly understood from the theoretical point of view.In our work,first-principles theoretical calculations are carried out to investigate the Li^+ions nucleation performance on metal-doped Cu surfaces(MDCSs)and the key descriptors that determines the properties of various MDCSs are systematically summarized.It is found that the introduction of heterogeneous doping Ag and Zn atoms will induce a gradient adsorption energy on MDCSs,and such gradient deposition sites can reduce the diffusion barriers and accelerate the diffusion rates of Li+ions dynamically.By maneuvering the Li+ions nucleation on MDCSs,a dendrite-free lithium metal anode can be achieved without the use of porous matrixes and complex synthesis process,which can be attributed to suppress the uncontrollable lithium dendrites for realizing the high-efficiency LMBs.
基金supported by the Czech Science Foundation(P107/11/1918)by the Ministry of Education,Youth and Sports of the Czech Republic in the“National Feasibility Program I”,project LO1208“TEWEP”by VSB‐Technical University of Ostrava(SP 2014/55)
文摘Aqueous colloidal dispersions containing Znx Cd1‐x S quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide,in the presence of a cetyltrimethylammonium bromide stabilizer.Ultraviolet‐visible absorption spectroscopy was used to determine the transition energies of the QDs,which in turn were used to calculate their sizes,which depended on their composition.The QD size decreased with increasing Zn content.The photocatalytic activity of the Znx Cd1‐x S QDs was studied by the decomposition of methylene blue under ultraviolet irradiation,at a maximum intensity at 365 nm (3.4 e V).Three different photo‐catalytic activity regions were observed,which depended on the Zn content.The quantum levels of the QDs could be excited by incident irradiation,and influenced the resulting photocatalytic activity.Maximum photocatalytic activity was achieved at x = 0.6,where the QD transition energy was equal to the irradiation photon energy.The photocatalytic efficiency of the QDs depended on their surface area and arrangement of quantum levels,because of the quantum size effect.
文摘Detecting COVID-19 cases as early as possible became a critical issue that must be addressed to avoid the pandemic’s additional spread and early provide the appropriate treatment to the affected patients.This study aimed to develop a COVID-19 diagnosis and prediction(AIMDP)model that could identify patients with COVID-19 and distinguish it from other viral pneumonia signs detected in chest computed tomography(CT)scans.The proposed system uses convolutional neural networks(CNNs)as a deep learning technology to process hundreds of CT chest scan images and speeds up COVID-19 case prediction to facilitate its containment.We employed the whale optimization algorithm(WOA)to select the most relevant patient signs.A set of experiments validated AIMDP performance.It demonstrated the superiority of AIMDP in terms of the area under the curve-receiver operating characteristic(AUC-ROC)curve,positive predictive value(PPV),negative predictive rate(NPR)and negative predictive value(NPV).AIMDP was applied to a dataset of hundreds of real data and CT images,and it was found to achieve 96%AUC for diagnosing COVID-19 and 98%for overall accuracy.The results showed the promising performance of AIMDP for diagnosing COVID-19 when compared to other recent diagnosing and predicting models.
基金This article was financed from the budget of the Student Grant Competition VSB-TUO(Registration No.SGS SP2020/135)This article has been elaborated in the framework of scholarship of the City of Ostrava(RRC/2806/2019)+1 种基金in the framework of the grant programme“Support for Science and Research in the Moravia-Silesia Region 2018”(RRC/10/2018)financed from the budget of the Moravian-Silesian Region.
文摘This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards.This composite material is made of gypsum and reinforcing natural fibers.The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum.From this composite material,high-strength plasterboards could then be produced,which meet the higher demands of users than conventional gypsum plasterboards.For their production,natural waste materials would be used efficiently.As part of the development of new building materials,it is necessary to specify essential characteristics for their later use in civil engineering.Crushed wheat straw and three gypsum classes with strengths G2(2 MPa)—gypsum Class I.,G5(5 MPa)—gypsum Class II.and G16(16 MPa)—gypsum Class III.were used to create the test samples.Samples were made with different ratios of the two ingredients,with the percentages of straw being 0%,2.5%,and 5%for each gypsum grade.The first part of the article describes how the increasing proportion of straw affects the composite’s mechanical properties(flexural strength and compressive strength).The second part of the article focuses on the change of thermal properties(thermal conductivity and specific heat capacity).The last part of the article mentions the verification of the fire properties(single-flame source fire test and gross heat of combustion)of this composite material.The research has shown that the increasing proportion of straw reinforcement caused a deterioration in the flexural strength(up to 56.49%in the 3.series of gypsum Class II.)and compressive strength(up to 80.27%in the 3.series of gypsum Class III.)and an improvement in the specific heat capacity and thermal conductivity(up to 31.40%in the 3.series).This composite material is thus not suitable for the production of high-strength plasterboards,but its reduced mechanical properties do not prevent its use for interior plasters.Based on the performed fire tests,it can be said that this composite material can be classified as a non-flammable material of reaction to fire Classes A1 or A2.From an ecological point of view,it is advantageous to use a composite material with a higher straw content.
文摘In this paper, the system performance of a decode-and-forward(DF) full-duplex(FD) adaptive relaying network over the Rician fading environment is proposed, analyzed and demonstrated. In the first stage, the system is presented with the energy harvesting and information transmission processes. After that, the analytical expressions of the achievable throughput, the outage probability, and symbol error ratio(SER) were proposed, analyzed and demonstrated. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions in the influence of the key system parameters. The results show that the analytical and simulated results match for all possible parameter values.
基金the context of the international DECOVALEX Project (DEmonstration of COupled models and their VALidation against EXperiments)financed by Radioactive Waste Repository Authority (RAWRA),through Technical University of Liberec (TUL), Czech RepublicSKB through its sp Pillar Stability Experiment project
文摘The paper describes an analysis of thermo-mechanical (TM) processes appearing during the Aspo Pillar Stability Experiment (APSE). This analysis is based on finite elements with elasticity, plasticity and dam- age mechanics models of rock behaviour and some least squares calibration techniques. The main aim is to examine the capability of continuous mechanics models to predict brittle damage behaviour of gran- ite rocks. The performed simulations use an in-house finite element software GEM and self-developed experimental continuum damage MATLAB code. The main contributions are twofold. First, it is an inverse analysis, which is used for (1) verification of an initial stress measurement by back analysis of conver- gence measurement during construction of the access tunnel and (2) identification of heat transfer rock mass properties by an inverse method based on the known heat sources and temperature measurements. Second, three different hierarchically built models are used to estimate the pillar damage zones, i.e. elas- tic model with Drucker-Prager strength criterion, elasto-plastic model with the same yield limit and a combination of elasto-plasticity with continuum damage mechanics. The damage mechanics model is also used to simulate uniaxial and triaxial compressive strength tests on the ,Aspo granite.
基金the support of the project(SP2017/22)which is the base of this articlepartially supported by the Slovak Research and Development Agency under contract No.APVV-0129-12the Scientific Grant Agency of the Ministry of Education,Science,Research and Sport of the Slovak Republic and the Slovak Academy of Sciences(VEGA)within the project No.1/0559/17 and APVV 1/0462/16。
文摘This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaskanear Banska Bystrica in Slovakia.The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material.Its maximum thickness is 3 m.Another specificific condition of the study area is its location in the built-up area,due to which the applicability of geophysical methods was limited.The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill,which complicates the identification of cave spaces.The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.
基金This work was supported by the EU H2020 project NOVAMAG(686056)and the Austrian Science Fund FWF(I3288-N36).Sergiu Arapan and Pablo Nieves acknowledge the European Regional Development Fund in the IT4Innovations National Supercomputing Center—path to exascale project(CZ 02.1.01/0.0/0.0/16-013/0001791)within the Operational Programme Research,Development and Education,and IT4Innovations computational resources allocated within projects OPEN-11-33,OPEN-14-23,and OPEN-17-14.
文摘Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive field and expected energy density product of a magnet made from a novel magnetic material composition.Iron(Fe)-rich magnetic phases suitable for permanent magnets can be found by means of adaptive genetic algorithms.The intrinsic properties computed by ab initio simulations are used as input for micromagnetic simulations of the hysteresis properties of permanent magnets with a realistic structure.Using machine learning techniques,the magnet’s structure can be optimized so that the upper limits for coercivity and energy density product for a given phase can be estimated.Structure property relations of synthetic permanent magnets were computed for several candidate hard magnetic phases.The following pairs(coercive field(T),energy density product(kJ·m^-3))were obtained for iron-tin-antimony(Fe3Sn0.75Sb0.25):(0.49,290),L10-ordered iron-nickel(L10 FeNi):(1,400),cobalt-iron-tantalum(CoFe6Ta):(0.87,425),and manganese-aluminum(MnAl):(0.53,80).
基金the Ministry of Health,Czech Republic Conceptual Development of Research Organization(FNOs/2017).
文摘AIM:To assess the role of orthoptics in referring patients with orbital floor blowout fracture(OFBF)for conservative or surgical treatment and based on the results,to propose a scoring system for such decision making.METHODS:A retrospective analysis of 69 patients with OFBF was performed(35 treated conservatively,34 surgically).The role of orthoptics in referring to surgery or conservative treatment was retrospectively evaluated,the factors with the highest significance for decision making were identified,and a scoring system proposed using Logistic regression.RESULTS:According to defined criteria,the treatment was unsuccessful in 2(6%)surgically treated and only in one(3%)conservatively treated patient.The proposed scoring system includes the defect size and several values resulting from the orthoptic examination,the elevation of the eyebulb measured on Lancaster screen being the most significant.CONCLUSION:The study demonstrates the benefits of orthoptic examination when making decisions on conservative or surgical treatment and for diagnosing ocular motility disorder(with or without binocular diplopia)in OFBF patients.The proposed scoring system could,following verification in a prospective study,become a valuable adjunctive tool.
基金by the Slovak Scientific Grant Agency VEGA[Grant Nos.1/0277/15 and 1/0222/19]the Project Institute of Clean Technologies for Mining and Utilization of Raw Materials for Energy Use[Grant No.LO1406].
文摘The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content(from 47.4 percent up to 82 percent),to compare and to analyze the potential use of the recycled fibers for building application,such as plastering mortar.Changes in the chemical composition,cellulose crystallinity and degree of polymerization of the fibers were found.The recycled fibers of lower quality showed heterogeneity in the fiber sizes(width and length),and they had greater surface roughness in comparison to high purity wood pulp samples.The high purity fibers(cellulose content>80.0 percent)had greater crystallinity and more homogeneous and smooth surfaces than the recycled fibers.The presence of calcite and kaolinite in all of the recycled cellulosic fibers samples was confirmed,whereas only one wood pulp sample contained calcite.The influence of the chemical composition was reflected in the fiber density values.Changes in the chemical composition and cellulose structure of the fibers affected the specific surface area,porosity and thermo physical properties of the fibers.More favorable values of thermal conductivity were reached for the recycled fibers than for the wood pulp samples.Testing the suitability of the recycled fibers with inorganic impurities originating from the paper-making processes for their use as fillers in plastering mortars(0.5 wt.%fiber content of the total weight of the filler and binder)confirmed their application by achieving a compressive strength value of 28 day-cured fiber-cement mortar required by the standard as well as by measured more favorable value of capillary water absorption coefficient.
基金financially supported by the National Natural Science Foundation of China(51702225,51672181,52071225)the National Key R&D Program of China(2019YFA0708201)+3 种基金the China Post-doctoral Foundation(7131705619)the Czech Republic from ERDF“Institute of Environmental Technology-Excel ent Research”(No.CZ.02.1.01/0.0/0.0/16_019/0000853)the Sino-German Research Institute for support(project:GZ 1400)the support from Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies,Suzhou,China。
文摘Among various anode candidates for potassium-ion batteries,carbonaceous materials have attracted significant attention due to their overwhelming advantages including cost-effectiveness and environmental benignity.However,the inferior specific capacity and the sluggish reaction kinetics hinder the further development in this realm.Herein,we report biomass templated synthesis of boron/oxygen heteroatom co-doped carbon particles(BO-CPs)via direct plasma-enhanced chemical vapor deposition.With the combined advantages of abundant active sites,large accessible surface area,and functional groups,BO-CP anode exhibits high reversible specific capacity(426.5 mAh g^(-1)at 0.1 A g^(-1))and excellent rate performance(166.5 mAh g^(-1)at 5 A g^(-1)).The K-ion storage mechanism is probed by operando Raman spectroscopy,ex situ X-ray photoelectron spectroscopy/electrochemical impedance spectroscopy,galvanostatic intermittent titration technique measurements,and theoretical simulations.The synergistic effect of boron and oxygen co-doping greatly facilitates the performance of carbon-based anode,wherein boron dopant improves the conductivity of carbon framework and the oxygen dopant affords ample active sites and thus harvests additional specific capacity.This work is anticipated to propel the development of high-performance anode materials for emerging energy storage devices.
基金Czech Science Foundation for their support of project(GACR-105/09/1631)
文摘The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes, especially including appropriate land-use planning. However, the relationship between relevant geological information and the geological environment is vital for foundation engineering purposes, especially where demanding structures are involved. This information is most conveniently structured when accumulated information concerning engineering-geological zones is utilized. This necessarily includes knowledge of rock workability and also of the pre-Quaternary bedrock, and these characteristics were then related to the current built-up area and future development according to the land-use plans in a case study are from the Petrvald Region (Czech Republic). The geological environment of area has been severely influenced by anthropogenic effects of deep black coal mining. Results of this research showed that future development should be founded on spoil banks, dumps, and settling basins. According to the land-use plan, this zone occupies 44.9% of the area of interest, and its materials predominantly emanate from mining in the Ostrava-Karvina Coal District. For future foundation structures planned there, it is imperative to consult detailed engineering-geological study. However, attention to and reliance on this necessity is not reflected in the existing land-use plan.