The amalgamation of artificial intelligence(AI)with various areas has been in the picture for the past few years.AI has enhanced the functioning of several services,such as accomplishing better budgets,automating mult...The amalgamation of artificial intelligence(AI)with various areas has been in the picture for the past few years.AI has enhanced the functioning of several services,such as accomplishing better budgets,automating multiple tasks,and data-driven decision-making.Conducting hassle-free polling has been one of them.However,at the onset of the coronavirus in 2020,almost all worldly affairs occurred online,and many sectors switched to digital mode.This allows attackers to find security loopholes in digital systems and exploit them for their lucrative business.This paper proposes a three-layered deep learning(DL)-based authentication framework to develop a secure online polling system.It provides a novel way to overcome security breaches during the face identity(ID)recognition and verification process for online polling systems.This verification is done by training a pixel-2-pixel Pix2pix generative adversarial network(GAN)for face image reconstruction to remove facial objects present(if any).Furthermore,image-to-image matching is done by implementing the Siamese network and comparing the result of various metrics executed on feature embeddings to obtain the outcome,thus checking the electorate credentials.展开更多
In order to achieve a lower consumed energy, the performance of a new type of rotating volumetric pump with two profiled rotors (variant I) which is compared with a centrifugal pump (variant II) is presented. The...In order to achieve a lower consumed energy, the performance of a new type of rotating volumetric pump with two profiled rotors (variant I) which is compared with a centrifugal pump (variant II) is presented. The analysis regarding the same flow rate of transported liquid and the same pressure increases points out the conduct of the system at the variation of the key operating parameters. The actual driving power of the rotating volumetric pump is higher stating that is more advantageous in operation. The effective efficiency of the system is improved due to the original constructive solution.展开更多
The overgrowth of weeds growing along with the primary crop in the fields reduces crop production.Conventional solutions like hand weeding are labor-intensive,costly,and time-consuming;farmers have used herbicides.The...The overgrowth of weeds growing along with the primary crop in the fields reduces crop production.Conventional solutions like hand weeding are labor-intensive,costly,and time-consuming;farmers have used herbicides.The application of herbicide is effective but causes environmental and health concerns.Hence,Precision Agriculture(PA)suggests the variable spraying of herbicides so that herbicide chemicals do not affect the primary plants.Motivated by the gap above,we proposed a Deep Learning(DL)based model for detecting Eggplant(Brinjal)weed in this paper.The key objective of this study is to detect plant and non-plant(weed)parts from crop images.With the help of object detection,the precise location of weeds from images can be achieved.The dataset is collected manually from a private farm in Gandhinagar,Gujarat,India.The combined approach of classification and object detection is applied in the proposed model.The Convolutional Neural Network(CNN)model is used to classify weed and non-weed images;further DL models are applied for object detection.We have compared DL models based on accuracy,memory usage,and Intersection over Union(IoU).ResNet-18,YOLOv3,CenterNet,and Faster RCNN are used in the proposed work.CenterNet outperforms all other models in terms of accuracy,i.e.,88%.Compared to other models,YOLOv3 is the least memory-intensive,utilizing 4.78 GB to evaluate the data.展开更多
The rapid degradation of magnesium(Mg)-based implants in physiological environment limits its clinical applications, and alloying treatment is an effective way to regulate the degradation rate of Mg-based materials. I...The rapid degradation of magnesium(Mg)-based implants in physiological environment limits its clinical applications, and alloying treatment is an effective way to regulate the degradation rate of Mg-based materials. In the present study, three Mg alloys, including Mg-0.8Ca(denoted as ZQ), Mg-0.8Ca-5Zn-1.5Ag(denoted as ZQ71) and Mg-0.8Ca-5Zn-2.5Ag(denoted as ZQ63), were fabricated by alloying with calcium(Ca), zinc(Zn) and silver(Ag). The results obtained from electrochemical corrosion tests and in vitro degradation evaluation demonstrated that the three Mg alloys exhibited distinct corrosion resistance, and ZQ71 exhibited the lowest degradation rate in vitro among them. After addition of Zn and Ag, the antibacterial potential of Mg alloys was also enhanced. The in vitro cell experiments showed that all the three Mg alloys had good biocompatibility. After implantation in a rat femoral defect, ZQ71 showed significantly higher osteogenic activity and bone substitution rate than ZQ63 and ZQ, due to its higher corrosion resistance as well as the stimulatory effects of the released metallic ions. In addition, the average daily degradation rate of each Mg alloy in vivo was significantly higher than that in vitro, as could be due to the implantation site located in the highly vascularized trabecular region. Importantly, the correlations between the in vitro and in vivo degradation parameters of the Mg alloys were systematically analyzed to find out the potential predictors of the in vivo degradation performance of the materials. The current work not only evaluated the clinical potential of the three biodegradable Mg alloys as bone grafts but also provided a feasible approach for predicting the in vivo degradation behavior of biodegradable materials.展开更多
Based on the Second Law of Thermodynamics, the entropy generation is studied for laminar forced convection flow of different nanoparticles(Al_2 O_3, CuO and SiO_2) mixed with water through a hexagon microchannel heat ...Based on the Second Law of Thermodynamics, the entropy generation is studied for laminar forced convection flow of different nanoparticles(Al_2 O_3, CuO and SiO_2) mixed with water through a hexagon microchannel heat sink(HMCHS). The effects of different heat fluxes and Reynolds numbers on the entropy generation for different nanofluids, volume fractions and nanoparticles diameter are investigated. The heat flux is in the range of 125 to 500 kW·m^(-2) and the Reynolds numbers vary between 200 and 1500. The thermal, frictional and total entropy generations are calculated by integrating the volumetric rate components over the entire HMCHS. The results clearly show that the rise in the heat flux leads to an increase in the thermal entropy generation for nanofluids and pure water but they don't have any influence on the frictional entropy generation. Moreover, when the Reynolds number increases, the frictional entropy generation increases while the thermal entropy generation decreases. The results revealed that at low heat fluxes and high Reynolds numbers, pure water gives the lowest entropy generation, while at high heat flux the nanofluid has to be used in order to lower the overall irreversibility.展开更多
Modeling and simulation of photovoltaic (PV) systems represents an essential task for the integration of PV panels in current power applications. At the present time, there are sizing tools of photovoltaic systems ava...Modeling and simulation of photovoltaic (PV) systems represents an essential task for the integration of PV panels in current power applications. At the present time, there are sizing tools of photovoltaic systems available on the market, taking into account the proposed energy consumption, site localization and system cost. An advanced specialized program (PVSyst) was considered. The sizing and simulations of two PV important applications were developed using PV modules based on three different technologies: monocrystalline and polycrystalline silicon, as well as CIS. Our results showed how different types of solar cell technologies influenced the final power output and performances for a PV LED lighting, as well as for a PV water pumping system, in terms of overall yield, efficiency and system availability.展开更多
PLLA-magnesium composites have been widely investigated as potential biodegradable materials for bone implants.Lower/higher corrosion resistance of the crystalized/amorphous magnesium alloys allows tailoring of biodeg...PLLA-magnesium composites have been widely investigated as potential biodegradable materials for bone implants.Lower/higher corrosion resistance of the crystalized/amorphous magnesium alloys allows tailoring of biodegradability rate.In this work,the amorphous Mg_(65)Zn_(30)Ca_(5)was investigated versus traditional crystalized Mg_(65)Zn_(30)Ca_(5),and a PLLA-Mg_(65)Zn_(30)Ca_(5)composite has been successfully fabricated using hot injection process.Furthermore,the high corrosion resistance of the amorphous Mg_(65)Zn_(30)Ca_(5)prevented the high alkalization and deterioration of mechanical strength.In addition,the high Zn content intended to improve the glass forming ability,also enhances the anti-bacterial property of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite.The remarkable performance of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite shows its promising application in bone repair and tissue regeneration.展开更多
Starting with Faraday’s law of electromagnetic induction in 1831,electric(electromagnetic)machines have been developed ever since as“assembles”of electric and magnetic coupled circuits that convert mechanical to el...Starting with Faraday’s law of electromagnetic induction in 1831,electric(electromagnetic)machines have been developed ever since as“assembles”of electric and magnetic coupled circuits that convert mechanical to electrical energy(in generators)and vice versa(in motors),via magnetic energy storage.Generators and motors are reversible.The Maxwell four equations(laws)later in 19th Century have prompted the rapid development of all basic(DC.brush and travelling field AC machines by 1900.Then by 1930 AC(alternating current)power(energy)systems evolved by connecting in parallel electric synchronous generators(with voltage boost and buck electric transformers for efficient AC power transmission lines)of rather constant frequency and voltage,driven by turbines(prime movers)that harness fossil(coal,gas or nuclear fuels),thermal or hydro energy.The last 50 years have witnessed a dramatic extension of generators power/unit,renewable energy generators and of variable speed AC motor drives in applications with variable output such as ventilators,pumps compressors,conveyors,orr-mills,electric transport(mobility),industrial automation,robotics,home appliances and info-gadgets.This formidable development,required by the need of more but cleaner energy,was mainly driven by power electronics,better materials,better modeling,design methodologies and digital control.This humble inaugural overview attempts to combine a brief history of electrical generators and motors with recent progress and trends in their design and control,for representative applications.展开更多
Currently, there are various reels on the market regarding the type of mechanism, which achieves the winding and unwinding of the line. The designers have the purpose of obtaining a linear transmission function, by me...Currently, there are various reels on the market regarding the type of mechanism, which achieves the winding and unwinding of the line. The designers have the purpose of obtaining a linear transmission function, by means of a simple and small-sized mechanism. However, the present solutions are not satisfactory because of large deviations from linearity of the transmission function and complexity of mechanical schema. A novel solution for the reel spool mechanism is proposed. Its kinematic schema and synthesis method are described. The kinematic schema of the chosen mechanism is based on a noncircular gear in series with a scotch-yoke mechanism. The yoke is driven by a stud fixed on the driving noncircular gear. The drawbacks of other models regarding the effects occurring at the ends of the spool are eliminated through achieving an appropriate transmission function of the spool. The linear function approximation with curved end-arches appropriately computed to ensure mathematical continuity is very good. The experimental results on the mechanism model validate the theoretical approach. The developed mechanism solution is recorded under a reel spool mechanism patent.展开更多
This paper presents a model of automatic negotiation agents in an open environment. Agents are motivated by the gain they may obtain while fulfilling their goals, but their behaviour can change during negotiation acco...This paper presents a model of automatic negotiation agents in an open environment. Agents are motivated by the gain they may obtain while fulfilling their goals, but their behaviour can change during negotiation according to previous interactions with other agents in the system. Changing behaviour may refer to either the use of different negotiation strategies or to concessions made for other agents, with which they have successfully negotiated in the past. To this aim, an agent develops a set of partners’ profiles during negotiation: the preference profile, the cooperation profile, and the group negotiation profile. The first two profiles characterize individuals, while in a group negotiation profile, several agent profiles are clustered according to commonly discovered features. Different approaches to the development of these profiles are presented.展开更多
Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform...Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform the processing and analysis of geomagnetic parameters through different spectral,statistical and correlation methods.All these parameters are included in the geomagnetic database on server.The web interface for the database meets the different needs of handling the data collected,raw or processed.The server-side programming language used for design is php.This allow us to select different periods for which access to stored data,required for different search filters and different parameters or data from different time periods can be compared.For a more in-depth analysis of the stored data,through JavaScript programming language graphs for different parameters can be drawn.Access to the web interface can be done with or without authentication,depending on the need to ensure the security of certain data collected,stored and processed.The applications are scalable for different devices that will access it:mobile,tablets,laptops or desktops.展开更多
The purpose of this study was to analyze the associated spectrum of geomagnetic field,frequencies intensity and the time of occurrence.We calculated the variation of the correlation coefficients,with mobile windows of...The purpose of this study was to analyze the associated spectrum of geomagnetic field,frequencies intensity and the time of occurrence.We calculated the variation of the correlation coefficients,with mobile windows of various sizes,for the recorded magnetic components at different latitudes and latitudes.The observatories we included in our study are USA(Surlari),HON(Honolulu),SBA(Scott Base),KAK(Kakioka),THY(Tihany),UPS(Uppsala),WNG(Wingst)and Yellowknife(YKC).We used the data of these observatories from International Real-time Magnetic Observatory Network(INTERMAGNET)for the geomagnetic storm from October 28-31,2003.We have used for this purpose a series of filtering algorithms,spectral analysis and wavelet with different mother functions at different levels.In the paper,we show the Fourier and wavelet analysis of geomagnetic data recorded at different observatories regarding geomagnetic storms.Fourier analysis hightlights predominant frequencies of magnetic field components.Wavelet analysis provides information about the frequency ranges of magnetic fields,which contain long time intervals for medium frequency information and short time intervals for highlight frequencies,details of the analyzed signals.Also,the wavelet analysis allows us to decompose geomagnetic signals in different waves.The analyses presented are significant for the studies of the geomagnetic storm.The data for the next days after the storm showed a mitigation of the perturbations and a transition to quiet days of the geomagnetic field.展开更多
Electropolymerization and characterization of poly(3,4-ethylene dioxythiophene) (PEDOT) doped with functionalized single-walled carbon nanotubes (SWANTs) polyaminobenzene sulfonic acid (PABS) and different dopants wer...Electropolymerization and characterization of poly(3,4-ethylene dioxythiophene) (PEDOT) doped with functionalized single-walled carbon nanotubes (SWANTs) polyaminobenzene sulfonic acid (PABS) and different dopants were studied. It was fabricated by a simple oxidative electropolymerization method. The nanocomposite coatings have been prepared by using electrochemical methods from aqueous solutions, such that the components were deposited onto platinum electrode substrate. The morphology of composite films was analyzed by scanning electron microscopy (SEM). The electrochemical and physical properties of the resulting composites were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FT-IR) techniques in 0.1 M LiClO4 aqueous solutions. The value of specific electrochemical capacitance of the composite films is considerably higher than that of the pure polymers films. The improved properties of the electrodes were obtained by using these composite films. The dopant substances used were sodium dodecyl sulfate (SDS) and 1,2-Dihydroxy- benzene-3,5-disulfonic acid disodium salt hydrate (tiron).展开更多
The electrical properties of magnetic sensing devices fabricated from anisotropic materials are not easily extracted. Here we present a method for determining the resistance matrix for an anisotropic device with multi...The electrical properties of magnetic sensing devices fabricated from anisotropic materials are not easily extracted. Here we present a method for determining the resistance matrix for an anisotropic device with multiple electrical contacts placed in a perpendicular magnetic field. By using the methods developed by Van der Pauw and Wasscher, the analysis for the anisotropic system is reduced to the equivalent problem for an isotropic sample, which can then be solved using methods developed previously. As a result, the method works in the case of structures with an arbitrary number of asymmetric extended contacts at large magnetic field strength. In addition to the extraction of nonisotropic resistivities, the resistance matrix can be used to analyze the Hall effect for anisotropic plates.展开更多
Maxwell-Vlasov PDEs system describes the dynamics of plasma consisting of charged particles with long-range inter-action. Their solutions can be written using some Stokes potentials. Section 1 presents the experimenta...Maxwell-Vlasov PDEs system describes the dynamics of plasma consisting of charged particles with long-range inter-action. Their solutions can be written using some Stokes potentials. Section 1 presents the experimental devices which can produce a magnetic trap. Magnetic geometric dynamic provides mathematical tools for describing the magnetic flow (see [1-7]). Stokes representation for the solutions of PDEs as Maxwell PDEs or Maxwell-Vlasov PDEs are used analyzing electromagnetic energy in magnetic traps. Section 2 studies Maxwell-Vlasov PDEs system. Stokes represen-tation of its solutions, using Maximum Principle for a multitime optimal control problem, is obtained. Section 3 dis-cusses a method for changing a given ODEs system into a geodesic motion under a gyroscopic field of forces (geomet-ric dynamics). Section 4 proposes a modified form for Maxwell-Vlasov PDEs, by replacing the classical gyroscopic force with the one appearing in geometric dynamics. Stokes representation for the solutions of modified Max-well-Vlasov PDEs is also obtained.展开更多
基金funded by the Researchers Supporting Project Number(RSP2023R 102)King Saud University,Riyadh,Saudi Arabia.
文摘The amalgamation of artificial intelligence(AI)with various areas has been in the picture for the past few years.AI has enhanced the functioning of several services,such as accomplishing better budgets,automating multiple tasks,and data-driven decision-making.Conducting hassle-free polling has been one of them.However,at the onset of the coronavirus in 2020,almost all worldly affairs occurred online,and many sectors switched to digital mode.This allows attackers to find security loopholes in digital systems and exploit them for their lucrative business.This paper proposes a three-layered deep learning(DL)-based authentication framework to develop a secure online polling system.It provides a novel way to overcome security breaches during the face identity(ID)recognition and verification process for online polling systems.This verification is done by training a pixel-2-pixel Pix2pix generative adversarial network(GAN)for face image reconstruction to remove facial objects present(if any).Furthermore,image-to-image matching is done by implementing the Siamese network and comparing the result of various metrics executed on feature embeddings to obtain the outcome,thus checking the electorate credentials.
文摘In order to achieve a lower consumed energy, the performance of a new type of rotating volumetric pump with two profiled rotors (variant I) which is compared with a centrifugal pump (variant II) is presented. The analysis regarding the same flow rate of transported liquid and the same pressure increases points out the conduct of the system at the variation of the key operating parameters. The actual driving power of the rotating volumetric pump is higher stating that is more advantageous in operation. The effective efficiency of the system is improved due to the original constructive solution.
基金funded by the Researchers Supporting Project Number(RSP2023R 509),King Saud University,Riyadh,Saudi Arabia.
文摘The overgrowth of weeds growing along with the primary crop in the fields reduces crop production.Conventional solutions like hand weeding are labor-intensive,costly,and time-consuming;farmers have used herbicides.The application of herbicide is effective but causes environmental and health concerns.Hence,Precision Agriculture(PA)suggests the variable spraying of herbicides so that herbicide chemicals do not affect the primary plants.Motivated by the gap above,we proposed a Deep Learning(DL)based model for detecting Eggplant(Brinjal)weed in this paper.The key objective of this study is to detect plant and non-plant(weed)parts from crop images.With the help of object detection,the precise location of weeds from images can be achieved.The dataset is collected manually from a private farm in Gandhinagar,Gujarat,India.The combined approach of classification and object detection is applied in the proposed model.The Convolutional Neural Network(CNN)model is used to classify weed and non-weed images;further DL models are applied for object detection.We have compared DL models based on accuracy,memory usage,and Intersection over Union(IoU).ResNet-18,YOLOv3,CenterNet,and Faster RCNN are used in the proposed work.CenterNet outperforms all other models in terms of accuracy,i.e.,88%.Compared to other models,YOLOv3 is the least memory-intensive,utilizing 4.78 GB to evaluate the data.
基金financially supported by InterGovernmental S&T Cooperation Project Between China and Romania (2018LMNY003)Sichuan Science and Technology Innovation Team of China (2019JDTD0008)the Fundamental Research Funds for the Central Universities (2021SCU12071)。
文摘The rapid degradation of magnesium(Mg)-based implants in physiological environment limits its clinical applications, and alloying treatment is an effective way to regulate the degradation rate of Mg-based materials. In the present study, three Mg alloys, including Mg-0.8Ca(denoted as ZQ), Mg-0.8Ca-5Zn-1.5Ag(denoted as ZQ71) and Mg-0.8Ca-5Zn-2.5Ag(denoted as ZQ63), were fabricated by alloying with calcium(Ca), zinc(Zn) and silver(Ag). The results obtained from electrochemical corrosion tests and in vitro degradation evaluation demonstrated that the three Mg alloys exhibited distinct corrosion resistance, and ZQ71 exhibited the lowest degradation rate in vitro among them. After addition of Zn and Ag, the antibacterial potential of Mg alloys was also enhanced. The in vitro cell experiments showed that all the three Mg alloys had good biocompatibility. After implantation in a rat femoral defect, ZQ71 showed significantly higher osteogenic activity and bone substitution rate than ZQ63 and ZQ, due to its higher corrosion resistance as well as the stimulatory effects of the released metallic ions. In addition, the average daily degradation rate of each Mg alloy in vivo was significantly higher than that in vitro, as could be due to the implantation site located in the highly vascularized trabecular region. Importantly, the correlations between the in vitro and in vivo degradation parameters of the Mg alloys were systematically analyzed to find out the potential predictors of the in vivo degradation performance of the materials. The current work not only evaluated the clinical potential of the three biodegradable Mg alloys as bone grafts but also provided a feasible approach for predicting the in vivo degradation behavior of biodegradable materials.
基金the Politehnica University of Bucharest in Romania for supporting this project financially
文摘Based on the Second Law of Thermodynamics, the entropy generation is studied for laminar forced convection flow of different nanoparticles(Al_2 O_3, CuO and SiO_2) mixed with water through a hexagon microchannel heat sink(HMCHS). The effects of different heat fluxes and Reynolds numbers on the entropy generation for different nanofluids, volume fractions and nanoparticles diameter are investigated. The heat flux is in the range of 125 to 500 kW·m^(-2) and the Reynolds numbers vary between 200 and 1500. The thermal, frictional and total entropy generations are calculated by integrating the volumetric rate components over the entire HMCHS. The results clearly show that the rise in the heat flux leads to an increase in the thermal entropy generation for nanofluids and pure water but they don't have any influence on the frictional entropy generation. Moreover, when the Reynolds number increases, the frictional entropy generation increases while the thermal entropy generation decreases. The results revealed that at low heat fluxes and high Reynolds numbers, pure water gives the lowest entropy generation, while at high heat flux the nanofluid has to be used in order to lower the overall irreversibility.
文摘Modeling and simulation of photovoltaic (PV) systems represents an essential task for the integration of PV panels in current power applications. At the present time, there are sizing tools of photovoltaic systems available on the market, taking into account the proposed energy consumption, site localization and system cost. An advanced specialized program (PVSyst) was considered. The sizing and simulations of two PV important applications were developed using PV modules based on three different technologies: monocrystalline and polycrystalline silicon, as well as CIS. Our results showed how different types of solar cell technologies influenced the final power output and performances for a PV LED lighting, as well as for a PV water pumping system, in terms of overall yield, efficiency and system availability.
基金supported by National Natural Science Foundation of China(Grant No.51471120)
文摘PLLA-magnesium composites have been widely investigated as potential biodegradable materials for bone implants.Lower/higher corrosion resistance of the crystalized/amorphous magnesium alloys allows tailoring of biodegradability rate.In this work,the amorphous Mg_(65)Zn_(30)Ca_(5)was investigated versus traditional crystalized Mg_(65)Zn_(30)Ca_(5),and a PLLA-Mg_(65)Zn_(30)Ca_(5)composite has been successfully fabricated using hot injection process.Furthermore,the high corrosion resistance of the amorphous Mg_(65)Zn_(30)Ca_(5)prevented the high alkalization and deterioration of mechanical strength.In addition,the high Zn content intended to improve the glass forming ability,also enhances the anti-bacterial property of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite.The remarkable performance of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite shows its promising application in bone repair and tissue regeneration.
文摘Starting with Faraday’s law of electromagnetic induction in 1831,electric(electromagnetic)machines have been developed ever since as“assembles”of electric and magnetic coupled circuits that convert mechanical to electrical energy(in generators)and vice versa(in motors),via magnetic energy storage.Generators and motors are reversible.The Maxwell four equations(laws)later in 19th Century have prompted the rapid development of all basic(DC.brush and travelling field AC machines by 1900.Then by 1930 AC(alternating current)power(energy)systems evolved by connecting in parallel electric synchronous generators(with voltage boost and buck electric transformers for efficient AC power transmission lines)of rather constant frequency and voltage,driven by turbines(prime movers)that harness fossil(coal,gas or nuclear fuels),thermal or hydro energy.The last 50 years have witnessed a dramatic extension of generators power/unit,renewable energy generators and of variable speed AC motor drives in applications with variable output such as ventilators,pumps compressors,conveyors,orr-mills,electric transport(mobility),industrial automation,robotics,home appliances and info-gadgets.This formidable development,required by the need of more but cleaner energy,was mainly driven by power electronics,better materials,better modeling,design methodologies and digital control.This humble inaugural overview attempts to combine a brief history of electrical generators and motors with recent progress and trends in their design and control,for representative applications.
基金Supported by an industrial commission developed at TU Dresden and think MOTION project,under the Information and Communication Technologies Policy Support ProgrammeArea:CIP-ICT-PSP.2009.2.3–Digital Libraries:European Digital Library Digitizing Content for Europeana(01.06.2010–31.05.2013)
文摘Currently, there are various reels on the market regarding the type of mechanism, which achieves the winding and unwinding of the line. The designers have the purpose of obtaining a linear transmission function, by means of a simple and small-sized mechanism. However, the present solutions are not satisfactory because of large deviations from linearity of the transmission function and complexity of mechanical schema. A novel solution for the reel spool mechanism is proposed. Its kinematic schema and synthesis method are described. The kinematic schema of the chosen mechanism is based on a noncircular gear in series with a scotch-yoke mechanism. The yoke is driven by a stud fixed on the driving noncircular gear. The drawbacks of other models regarding the effects occurring at the ends of the spool are eliminated through achieving an appropriate transmission function of the spool. The linear function approximation with curved end-arches appropriately computed to ensure mathematical continuity is very good. The experimental results on the mechanism model validate the theoretical approach. The developed mechanism solution is recorded under a reel spool mechanism patent.
文摘This paper presents a model of automatic negotiation agents in an open environment. Agents are motivated by the gain they may obtain while fulfilling their goals, but their behaviour can change during negotiation according to previous interactions with other agents in the system. Changing behaviour may refer to either the use of different negotiation strategies or to concessions made for other agents, with which they have successfully negotiated in the past. To this aim, an agent develops a set of partners’ profiles during negotiation: the preference profile, the cooperation profile, and the group negotiation profile. The first two profiles characterize individuals, while in a group negotiation profile, several agent profiles are clustered according to commonly discovered features. Different approaches to the development of these profiles are presented.
基金the Romanian Ministry of Education and Research for financing the projects:“The realization of 3D geological/geophysical models for the characterization of some areas of economic and scientific interest in Romania”,with Contract No.49N/2019“Institutional capacities and services for research,monitoring and forecasting of risks in extra-atmospheric space”,acronym SAFESPACE,Contract No.16PCCDI/2018,within PNCDIII.
文摘Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform the processing and analysis of geomagnetic parameters through different spectral,statistical and correlation methods.All these parameters are included in the geomagnetic database on server.The web interface for the database meets the different needs of handling the data collected,raw or processed.The server-side programming language used for design is php.This allow us to select different periods for which access to stored data,required for different search filters and different parameters or data from different time periods can be compared.For a more in-depth analysis of the stored data,through JavaScript programming language graphs for different parameters can be drawn.Access to the web interface can be done with or without authentication,depending on the need to ensure the security of certain data collected,stored and processed.The applications are scalable for different devices that will access it:mobile,tablets,laptops or desktops.
文摘The purpose of this study was to analyze the associated spectrum of geomagnetic field,frequencies intensity and the time of occurrence.We calculated the variation of the correlation coefficients,with mobile windows of various sizes,for the recorded magnetic components at different latitudes and latitudes.The observatories we included in our study are USA(Surlari),HON(Honolulu),SBA(Scott Base),KAK(Kakioka),THY(Tihany),UPS(Uppsala),WNG(Wingst)and Yellowknife(YKC).We used the data of these observatories from International Real-time Magnetic Observatory Network(INTERMAGNET)for the geomagnetic storm from October 28-31,2003.We have used for this purpose a series of filtering algorithms,spectral analysis and wavelet with different mother functions at different levels.In the paper,we show the Fourier and wavelet analysis of geomagnetic data recorded at different observatories regarding geomagnetic storms.Fourier analysis hightlights predominant frequencies of magnetic field components.Wavelet analysis provides information about the frequency ranges of magnetic fields,which contain long time intervals for medium frequency information and short time intervals for highlight frequencies,details of the analyzed signals.Also,the wavelet analysis allows us to decompose geomagnetic signals in different waves.The analyses presented are significant for the studies of the geomagnetic storm.The data for the next days after the storm showed a mitigation of the perturbations and a transition to quiet days of the geomagnetic field.
文摘Electropolymerization and characterization of poly(3,4-ethylene dioxythiophene) (PEDOT) doped with functionalized single-walled carbon nanotubes (SWANTs) polyaminobenzene sulfonic acid (PABS) and different dopants were studied. It was fabricated by a simple oxidative electropolymerization method. The nanocomposite coatings have been prepared by using electrochemical methods from aqueous solutions, such that the components were deposited onto platinum electrode substrate. The morphology of composite films was analyzed by scanning electron microscopy (SEM). The electrochemical and physical properties of the resulting composites were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FT-IR) techniques in 0.1 M LiClO4 aqueous solutions. The value of specific electrochemical capacitance of the composite films is considerably higher than that of the pure polymers films. The improved properties of the electrodes were obtained by using these composite films. The dopant substances used were sodium dodecyl sulfate (SDS) and 1,2-Dihydroxy- benzene-3,5-disulfonic acid disodium salt hydrate (tiron).
文摘The electrical properties of magnetic sensing devices fabricated from anisotropic materials are not easily extracted. Here we present a method for determining the resistance matrix for an anisotropic device with multiple electrical contacts placed in a perpendicular magnetic field. By using the methods developed by Van der Pauw and Wasscher, the analysis for the anisotropic system is reduced to the equivalent problem for an isotropic sample, which can then be solved using methods developed previously. As a result, the method works in the case of structures with an arbitrary number of asymmetric extended contacts at large magnetic field strength. In addition to the extraction of nonisotropic resistivities, the resistance matrix can be used to analyze the Hall effect for anisotropic plates.
文摘Maxwell-Vlasov PDEs system describes the dynamics of plasma consisting of charged particles with long-range inter-action. Their solutions can be written using some Stokes potentials. Section 1 presents the experimental devices which can produce a magnetic trap. Magnetic geometric dynamic provides mathematical tools for describing the magnetic flow (see [1-7]). Stokes representation for the solutions of PDEs as Maxwell PDEs or Maxwell-Vlasov PDEs are used analyzing electromagnetic energy in magnetic traps. Section 2 studies Maxwell-Vlasov PDEs system. Stokes represen-tation of its solutions, using Maximum Principle for a multitime optimal control problem, is obtained. Section 3 dis-cusses a method for changing a given ODEs system into a geodesic motion under a gyroscopic field of forces (geomet-ric dynamics). Section 4 proposes a modified form for Maxwell-Vlasov PDEs, by replacing the classical gyroscopic force with the one appearing in geometric dynamics. Stokes representation for the solutions of modified Max-well-Vlasov PDEs is also obtained.