The paper describes results obtained in the development of adaptive fuzzy-neural navigation subsystem for mobile legged robot. In order to keep the motion sufficiently smooth, free of sharp turnings and transversal sw...The paper describes results obtained in the development of adaptive fuzzy-neural navigation subsystem for mobile legged robot. In order to keep the motion sufficiently smooth, free of sharp turnings and transversal swings when moving between closely located obstacles, fuzzy rules are updated on-line. To this end, the fuzzy rules are expressed through a layered feed-forward neural network and parameters are updated on line in two steps--the rough and fine updating. That is followed by the description of the learning fault diagnosis using binary neural network based on the Carpenter and Grossbergs＇ adaptive resonance theory.展开更多
Diabetic Retinopathy(DR)is an eye disease that mainly affects people with diabetes.People affected by DR start losing their vision from an early stage even though the symptoms are identified only at the later stage.On...Diabetic Retinopathy(DR)is an eye disease that mainly affects people with diabetes.People affected by DR start losing their vision from an early stage even though the symptoms are identified only at the later stage.Once the vision is lost,it cannot be regained but can be prevented from causing any further damage.Early diagnosis of DR is required for preventing vision loss,for which a trained ophthalmologist is required.The clinical practice is time-consuming and is not much successful in identifying DR at early stages.Hence,Computer-Aided Diagnosis(CAD)system is a suitable alternative for screening and grading of DR for a larger population.This paper addresses the different stages in CAD system and the challenges in identifying and grading of DR by analyzing various recently evolved techniques.The performance metrics used to evaluate the Computer-Aided Diagnosis system for clinical practice is also discussed.展开更多
Emerging memristive devices offer enormous advantages for applications such as non-volatile memories and inmemory computing(IMC),but there is a rising interest in using memristive technologies for security application...Emerging memristive devices offer enormous advantages for applications such as non-volatile memories and inmemory computing(IMC),but there is a rising interest in using memristive technologies for security applications in the era of internet of things(IoT).In this review article,for achieving secure hardware systems in IoT,lowpower design techniques based on emerging memristive technology for hardware security primitives/systems are presented.By reviewing the state-of-the-art in three highlighted memristive application areas,i.e.memristive non-volatile memory,memristive reconfigurable logic computing and memristive artificial intelligent computing,their application-level impacts on the novel implementations of secret key generation,crypto functions and machine learning attacks are explored,respectively.For the low-power security applications in IoT,it is essential to understand how to best realize cryptographic circuitry using memristive circuitries,and to assess the implications of memristive crypto implementations on security and to develop novel computing paradigms that will enhance their security.This review article aims to help researchers to explore security solutions,to analyze new possible threats and to develop corresponding protections for the secure hardware systems based on low-cost memristive circuit designs.展开更多
The paper presents the measurement campaign of wind energy potential undertaken in Republic of Macedonia on four sites from the middle of 2006. The wind data analysis has been performed for one site, following with th...The paper presents the measurement campaign of wind energy potential undertaken in Republic of Macedonia on four sites from the middle of 2006. The wind data analysis has been performed for one site, following with the assessment of energy production of simulated wind park with six wind turbine generators.展开更多
Mossbauer spectroscopy was established as an analytical method 50 years ago and it is still of current interest in many disciplines as mineralogy, environmental science, archeology and biology. Areas of research where...Mossbauer spectroscopy was established as an analytical method 50 years ago and it is still of current interest in many disciplines as mineralogy, environmental science, archeology and biology. Areas of research where Mossbauer spectroscopy is contributing are metals and alloys, magnetic materials, chemical compounds and oxidation states, nanoparticles and many others. Different types of amorphous and nanocrystalline materials （e.g. finemet, nanoperm and hitperm） can be analyzed under different external influence like neutron irradiation or external magnetic field. Mineralogical samples as potassium white micas in sheared basement cover rocks from the Central Western Carpathians and meteorites can be also effectively investigated using MOssbauer spectroscopy. Phase analysis of meteorites can be helpful in their classification and moreover, particular magnetic and non-magnetic components can be analyzed in details. At present, the Mossbauer spectroscopy is also used to analyze environmental materials like zeolites, volcanic tephra and compounds containing ferrate （Fe6＋）.展开更多
The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data...The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data payload, from the sensor nodes to the base station or the cluster head according to the Time Division Multiple Access (TDMA) scheduling. Placing the short packets into appropriate slots and subslots in the TDMA frames transfers the information about the measured values and node identity. This paper presents the proof of concept of the proposed DTS protocol and provides verification of the energy savings using the QualNet®communication simulation platform (QualNet) and the SunTM Small Programmable Object Technology (Sun SPOT) testbed platform (for single hop and multi hop scenarios). The simulations and the testbed measurements confirm that the DTS protocol can provide energy savings up to 30% when compared with the IEEE 802.15.4 standard in unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) mode at 2.4 GHz frequency band.展开更多
This paper addresses to the problem of designing, modeling and practical realization of robust model predictive control for finite and infinite prediction horizon which ensures a parameter dependent quadratic stabilit...This paper addresses to the problem of designing, modeling and practical realization of robust model predictive control for finite and infinite prediction horizon which ensures a parameter dependent quadratic stability and guaranteed cost for linear polytopic uncertain systems. The model predictive controller design procedure based on BMI and LMI is reduced to off-line output feedback gain calculation. A numerical examples and an application to a real process is given to illustrate the effectiveness of the proposed method.展开更多
This paper describes a reactive navigation proposed for a differentially driven robot. The aim of the reactive navigation is to prescribe behavior to the robot based on actual sensor values that is collision-free. Ana...This paper describes a reactive navigation proposed for a differentially driven robot. The aim of the reactive navigation is to prescribe behavior to the robot based on actual sensor values that is collision-free. Analysis of reactive navigation methods shows that there is no reliable reactive collision-free method. However, method VFH＋ is suboptimal reactive navigation method for static environment. Original method was proposed for ultrasonic rangefinders. Nowadays, much more sophisticated sensors are available. That is why our modification is proposed for a laser rangefinder attached to indoor mobile robot. Results are presented as simulation in Matlab and also as experiments with real robot. Based on these experiments, it can be claimed that VFH＋ is very effective reactive navigation method for various sensors and environments and it can be modified for different requirements on robot behavior.展开更多
Since the amount of decentralised power generation is increasing, it is important to develop an energy management system for low-voltage grids. This paper presents a method to operate such a management system. The sys...Since the amount of decentralised power generation is increasing, it is important to develop an energy management system for low-voltage grids. This paper presents a method to operate such a management system. The system is designed for managing a group of smart houses which can consume or supply electrical energy. The aims are to reduce the transmission losses and to stay within the permitted limits of both the voltage drop and the utilisation of lines and transformers. The reduction of the losses is implemented in the LOMA （loss-optimising-management-algorithm）. This algorithm tries to find the power flow situation where minimal losses occur. The results of LOMA, the current power situation （in the low- and medium-voltage system） and the maximum power situation （based on grid parameters） are summarised in an individual incentive signal for every smart home, The simulations show the feasibility of such an energy management and a significant loss reduction.展开更多
Amorphous and nanocrystalline (Fe1–xNix)81Nb7B12 (x = 0, 0.25, 0.5, 0.75) alloys were measured by M?ssbauer spectrometry in the weak external magnetic field of 0.5 T. From structural analyses, ferromagnetic bcc-FeNi ...Amorphous and nanocrystalline (Fe1–xNix)81Nb7B12 (x = 0, 0.25, 0.5, 0.75) alloys were measured by M?ssbauer spectrometry in the weak external magnetic field of 0.5 T. From structural analyses, ferromagnetic bcc-FeNi and fcc-FeNi and paramagnetic (Fe-Ni)23B6 phases were identified in the annealed samples. It was shown that in the external magnetic field the intensities of the 2nd and the 5th lines (A23 parameter) are the most sensitive M?ssbauer parameters. Rather small changes were observed in the values of internal magnetic field. Our results showed that the amorphous precursor is more sensitive to the influence of external magnetic field than the nanocrystalline alloy. All spectra of amorphous precursor showed the increase of A23 parameter and decrease of internal magnetic field values of about 1 T (±0.5 T) under influence of external magnetic field. In the case of nanocrystalline samples the tendency for the values of internal magnetic field is similar but the effect is not so pronounced. The measurements confirmed that even weak external magnetic field affected orientation of the net magnetic moments. Our results indicate that effect of the external magnetic field is stronger in the case of amorphous samples due to their disordered structure.展开更多
Graphene’s unparalleled strength,chemical stability,ultimate surface-to-volume ratio and excellent electronic properties make it an ideal candidate as a material for membranes in micro-and nanoelectromechanical syste...Graphene’s unparalleled strength,chemical stability,ultimate surface-to-volume ratio and excellent electronic properties make it an ideal candidate as a material for membranes in micro-and nanoelectromechanical systems(MEMS and NEMS).However,the integration of graphene into MEMS or NEMS devices and suspended structures such as proof masses on graphene membranes raises several technological challenges,including collapse and rupture of the graphene.We have developed a robust route for realizing membranes made of double-layer CVD graphene and suspending large silicon proof masses on membranes with high yields.We have demonstrated the manufacture of square graphene membranes with side lengths from 7µm to 110µm,and suspended proof masses consisting of solid silicon cubes that are from 5µm×5µm×16.4µm to 100µm×100µm×16.4µm in size.Our approach is compatible with wafer-scale MEMS and semiconductor manufacturing technologies,and the manufacturing yields of the graphene membranes with suspended proof masses were>90%,with>70%of the graphene membranes having>90%graphene area without visible defects.The measured resonance frequencies of the realized structures ranged from tens to hundreds of kHz,with quality factors ranging from 63 to 148.The graphene membranes with suspended proof masses were extremely robust,and were able to withstand indentation forces from an atomic force microscope(AFM)tip of up to~7000nN.The proposed approach for the reliable and large-scale manufacture of graphene membranes with suspended proof masses will enable the development and study of innovative NEMS devices with new functionalities and improved performances.展开更多
Cost effective patterning based on scanning probe nanolithography(SPL)has the potential for electronic and optical nano-device manufacturing and other nanotechnological applications.One of the fundamental advantages o...Cost effective patterning based on scanning probe nanolithography(SPL)has the potential for electronic and optical nano-device manufacturing and other nanotechnological applications.One of the fundamental advantages of SPL is its capability for patterning and imaging employing the same probe.This is achieved with self-sensing and self-actuating cantilevers,also known as‘active'cantilevers.Here we used active cantilevers to demonstrate a novel path towards single digit nanoscale patterning by employing a low energy(<100 eV)electron exposure to thin films of molecular resist.By tuning the electron energies to the lithographically relevant chemical resist transformations,the interaction volumes can be highly localized.This method allows for greater control over spatially confined lithography and enhances sensitivity.We found that at low electron energies,the exposure in ambient conditions required approximately 10 electrons per single calixarene molecule to induce a crosslinking event.The sensitivity was 80-times greater than a classical electron beam exposure at 30 keV.By operating the electro-exposure process in ambient conditions a novel lithographic reaction scheme based on a direct ablation of resist material(positive tone)is presented.展开更多
Tungsten ditelluride(WTe_(2))is a layered transition metal dichalcogenide(TMD)that has attracted increasing research inter-est in recent years.WTe_(2) has demonstrated large non-saturating magnetoresistance,potential ...Tungsten ditelluride(WTe_(2))is a layered transition metal dichalcogenide(TMD)that has attracted increasing research inter-est in recent years.WTe_(2) has demonstrated large non-saturating magnetoresistance,potential for spintronic applications and promise as a type-II Weyl semimetal.The majority of works on WTe_(2) have relied on mechanically exfoliated flakes from chemical vapour transport(CVT)-grown crystals for their investigations.While producing high-quality samples,this method is hindered by several disadvantages including long synthesis time,high-temperature annealing and an inherent lack of scalability.In this work,a synthesis method is demonstrated that allows the production of large-area polycrystalline films of WTe_(2).This is achieved by the reaction of pre-deposited films of W and Te at a relatively low temperature of 550℃.Sputter X-ray photoelectron spectroscopy reveals the rapid but self-limiting nature of the oxidation of these WTe_(2) films in ambient conditions.The WTe_(2) films are composed of areas of micrometre-sized nanobelts that can be isolated and offer potential as an alternative to CVT-grown samples.These nanobelts are highly crystalline with low defect densities indicated by transmission electron microscopy and show promising initial electrical results.展开更多
In this paper we describe a hybrid system approach for high consumption industrial furnace control. The problem is observed in systematic way starting from the need for modeling this system as hybrid. For description ...In this paper we describe a hybrid system approach for high consumption industrial furnace control. The problem is observed in systematic way starting from the need for modeling this system as hybrid. For description of this behavior we use the Hybrid System Description Language. After that, we design an optimal controller for the furnace and we simulate and compare the controller with other relevant predictive controllers. We have shown that using the hybrid approach for control of industrial furnaces leads to significant improvement of the control system performances.展开更多
A novel image reversible data-hiding scheme based on primitive and varying radix numerical model is presented in this article.Using varying radix,variable sum of data may be embedded in various pixels of images.This s...A novel image reversible data-hiding scheme based on primitive and varying radix numerical model is presented in this article.Using varying radix,variable sum of data may be embedded in various pixels of images.This scheme is made adaptive using the correlation of the neighboring pixels.Messages are embedded as blocks of non-uniform length in the high-frequency regions of the rhombus mean interpolated image.A higher amount of data is embedded in the high-frequency regions and lesser data in the low-frequency regions of the image.The size of the embedded data depends on the statistics of the pixel distribution in the cover image.One of the major issues in reversible data embedding,the location map,is minimized because of the interpolation process.This technique,which is actually LSB matching,embeds only the residuals of modulo radix into the LSBs of each pixel.No attacks on this RDH technique will be able to decode the hidden content in the marked image.The proposed scheme delivers a prominent visual quality despite high embedding capacity.Experimental tests carried out on over 100 natural image data sets and medical images show an improvement in results compared to the existing schemes.Since the algorithm is based on the variable radix number system,it is more resistant to most of the steganographic attacks.The results were compared with a higher embedding capacity of up to 1.5 bpp reversible schemes for parameters like Peak Signal-to-Noise Ratio(PSNR),Embedding Capacity(EC)and Structural Similarity Index Metric(SSIM).展开更多
The documents contain a large amount of valuable knowledge on various subjects and, more recently, documents on the Internet are available from various sources. Therefore, automatic, rapid and accurate classification ...The documents contain a large amount of valuable knowledge on various subjects and, more recently, documents on the Internet are available from various sources. Therefore, automatic, rapid and accurate classification of these documents with less human interaction has become necessary. In this paper, we introduce a new algorithm called the highest repetition of words in a text document (HRWiTD) to classify the automatic Arabic text. The corpus is divided into a train set and a test set to be applied to proposed classification technique. The train set is analyzed for learning and the learning data is stored in the Learning Dataset file. The category that contains the highest repetition for each word is assigned as a category for the word in Learning Dataset file. This file includes non-duplicate words with the value of higher repetition and categories and they get from all texts in the train set. For each text in the test set, the category of words is assigned to a specific category by using Learning Dataset file. The category that contains the largest number of words is assigned as the predicted category of the text. To evaluate the classification accuracy of the HRWiTD algorithm, the confusion matrix method is used. The HRWiTD algorithm has been applied to convergent samples from six categories of Arabic news at SPA (Saudi Press Agency). As a result, the accuracy of the HRWiTD algorithm is 86.84%. In addition, we used the same corpus with the most popular machine learning algorithms which are C5.0, KNN, SVM, NB and C4.5, and their results of classification accuracy are 52.86%, 52.38%, 51.90%, 51.90% and 30%, respectively. Thus, the HRWiTD algorithm gives better classification accuracy compared to the most popular machine learning algorithms on the selected domain.展开更多
Detection of liquid mixture of different volume ratio is very important in industrial purposes. The paper reports a sensing mechanism of binary liquid mixture for different volume fraction, based on the measurement of...Detection of liquid mixture of different volume ratio is very important in industrial purposes. The paper reports a sensing mechanism of binary liquid mixture for different volume fraction, based on the measurement of refractive index of the mixture. Here, a highly sensitive liquid filled core Photonic Crystal Fiber structure has been proposed to detect liquid mixture solution. Numerical investigation of the proposed structure is carried out by employing full vectorial Finite Element Method (FEM).展开更多
文摘The paper describes results obtained in the development of adaptive fuzzy-neural navigation subsystem for mobile legged robot. In order to keep the motion sufficiently smooth, free of sharp turnings and transversal swings when moving between closely located obstacles, fuzzy rules are updated on-line. To this end, the fuzzy rules are expressed through a layered feed-forward neural network and parameters are updated on line in two steps--the rough and fine updating. That is followed by the description of the learning fault diagnosis using binary neural network based on the Carpenter and Grossbergs＇ adaptive resonance theory.
文摘Diabetic Retinopathy(DR)is an eye disease that mainly affects people with diabetes.People affected by DR start losing their vision from an early stage even though the symptoms are identified only at the later stage.Once the vision is lost,it cannot be regained but can be prevented from causing any further damage.Early diagnosis of DR is required for preventing vision loss,for which a trained ophthalmologist is required.The clinical practice is time-consuming and is not much successful in identifying DR at early stages.Hence,Computer-Aided Diagnosis(CAD)system is a suitable alternative for screening and grading of DR for a larger population.This paper addresses the different stages in CAD system and the challenges in identifying and grading of DR by analyzing various recently evolved techniques.The performance metrics used to evaluate the Computer-Aided Diagnosis system for clinical practice is also discussed.
基金supported by the DFG(German Research Foundation)Priority Program Nano Security,Project MemCrypto(Projektnummer 439827659/funding id DU 1896/2–1,PO 1220/15–1)the funding by the Fraunhofer Internal Programs under Grant No.Attract 600768。
文摘Emerging memristive devices offer enormous advantages for applications such as non-volatile memories and inmemory computing(IMC),but there is a rising interest in using memristive technologies for security applications in the era of internet of things(IoT).In this review article,for achieving secure hardware systems in IoT,lowpower design techniques based on emerging memristive technology for hardware security primitives/systems are presented.By reviewing the state-of-the-art in three highlighted memristive application areas,i.e.memristive non-volatile memory,memristive reconfigurable logic computing and memristive artificial intelligent computing,their application-level impacts on the novel implementations of secret key generation,crypto functions and machine learning attacks are explored,respectively.For the low-power security applications in IoT,it is essential to understand how to best realize cryptographic circuitry using memristive circuitries,and to assess the implications of memristive crypto implementations on security and to develop novel computing paradigms that will enhance their security.This review article aims to help researchers to explore security solutions,to analyze new possible threats and to develop corresponding protections for the secure hardware systems based on low-cost memristive circuit designs.
文摘The paper presents the measurement campaign of wind energy potential undertaken in Republic of Macedonia on four sites from the middle of 2006. The wind data analysis has been performed for one site, following with the assessment of energy production of simulated wind park with six wind turbine generators.
文摘Mossbauer spectroscopy was established as an analytical method 50 years ago and it is still of current interest in many disciplines as mineralogy, environmental science, archeology and biology. Areas of research where Mossbauer spectroscopy is contributing are metals and alloys, magnetic materials, chemical compounds and oxidation states, nanoparticles and many others. Different types of amorphous and nanocrystalline materials （e.g. finemet, nanoperm and hitperm） can be analyzed under different external influence like neutron irradiation or external magnetic field. Mineralogical samples as potassium white micas in sheared basement cover rocks from the Central Western Carpathians and meteorites can be also effectively investigated using MOssbauer spectroscopy. Phase analysis of meteorites can be helpful in their classification and moreover, particular magnetic and non-magnetic components can be analyzed in details. At present, the Mossbauer spectroscopy is also used to analyze environmental materials like zeolites, volcanic tephra and compounds containing ferrate （Fe6＋）.
文摘The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data payload, from the sensor nodes to the base station or the cluster head according to the Time Division Multiple Access (TDMA) scheduling. Placing the short packets into appropriate slots and subslots in the TDMA frames transfers the information about the measured values and node identity. This paper presents the proof of concept of the proposed DTS protocol and provides verification of the energy savings using the QualNet®communication simulation platform (QualNet) and the SunTM Small Programmable Object Technology (Sun SPOT) testbed platform (for single hop and multi hop scenarios). The simulations and the testbed measurements confirm that the DTS protocol can provide energy savings up to 30% when compared with the IEEE 802.15.4 standard in unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) mode at 2.4 GHz frequency band.
文摘This paper addresses to the problem of designing, modeling and practical realization of robust model predictive control for finite and infinite prediction horizon which ensures a parameter dependent quadratic stability and guaranteed cost for linear polytopic uncertain systems. The model predictive controller design procedure based on BMI and LMI is reduced to off-line output feedback gain calculation. A numerical examples and an application to a real process is given to illustrate the effectiveness of the proposed method.
文摘This paper describes a reactive navigation proposed for a differentially driven robot. The aim of the reactive navigation is to prescribe behavior to the robot based on actual sensor values that is collision-free. Analysis of reactive navigation methods shows that there is no reliable reactive collision-free method. However, method VFH＋ is suboptimal reactive navigation method for static environment. Original method was proposed for ultrasonic rangefinders. Nowadays, much more sophisticated sensors are available. That is why our modification is proposed for a laser rangefinder attached to indoor mobile robot. Results are presented as simulation in Matlab and also as experiments with real robot. Based on these experiments, it can be claimed that VFH＋ is very effective reactive navigation method for various sensors and environments and it can be modified for different requirements on robot behavior.
文摘Since the amount of decentralised power generation is increasing, it is important to develop an energy management system for low-voltage grids. This paper presents a method to operate such a management system. The system is designed for managing a group of smart houses which can consume or supply electrical energy. The aims are to reduce the transmission losses and to stay within the permitted limits of both the voltage drop and the utilisation of lines and transformers. The reduction of the losses is implemented in the LOMA （loss-optimising-management-algorithm）. This algorithm tries to find the power flow situation where minimal losses occur. The results of LOMA, the current power situation （in the low- and medium-voltage system） and the maximum power situation （based on grid parameters） are summarised in an individual incentive signal for every smart home, The simulations show the feasibility of such an energy management and a significant loss reduction.
文摘Amorphous and nanocrystalline (Fe1–xNix)81Nb7B12 (x = 0, 0.25, 0.5, 0.75) alloys were measured by M?ssbauer spectrometry in the weak external magnetic field of 0.5 T. From structural analyses, ferromagnetic bcc-FeNi and fcc-FeNi and paramagnetic (Fe-Ni)23B6 phases were identified in the annealed samples. It was shown that in the external magnetic field the intensities of the 2nd and the 5th lines (A23 parameter) are the most sensitive M?ssbauer parameters. Rather small changes were observed in the values of internal magnetic field. Our results showed that the amorphous precursor is more sensitive to the influence of external magnetic field than the nanocrystalline alloy. All spectra of amorphous precursor showed the increase of A23 parameter and decrease of internal magnetic field values of about 1 T (±0.5 T) under influence of external magnetic field. In the case of nanocrystalline samples the tendency for the values of internal magnetic field is similar but the effect is not so pronounced. The measurements confirmed that even weak external magnetic field affected orientation of the net magnetic moments. Our results indicate that effect of the external magnetic field is stronger in the case of amorphous samples due to their disordered structure.
基金We acknowledge support through a scholarship from China Scholarship Council,the Starting Grants M&M’s(277879)and InteGraDe(307311)as well as Graphene Flagship(785219)from the European Research Council,the Swedish Research Council(GEMS,2015-05112)+2 种基金the German Federal Ministry for Education and Research(NanoGraM,BMBF,03XP0006C)the German Research Foundation(DFG,LE 2440/1-2)the German Federal Ministry for Education and Research(BMBF:NanoGraM,03XP0006 and GIMMIK,03XP0210)。
文摘Graphene’s unparalleled strength,chemical stability,ultimate surface-to-volume ratio and excellent electronic properties make it an ideal candidate as a material for membranes in micro-and nanoelectromechanical systems(MEMS and NEMS).However,the integration of graphene into MEMS or NEMS devices and suspended structures such as proof masses on graphene membranes raises several technological challenges,including collapse and rupture of the graphene.We have developed a robust route for realizing membranes made of double-layer CVD graphene and suspending large silicon proof masses on membranes with high yields.We have demonstrated the manufacture of square graphene membranes with side lengths from 7µm to 110µm,and suspended proof masses consisting of solid silicon cubes that are from 5µm×5µm×16.4µm to 100µm×100µm×16.4µm in size.Our approach is compatible with wafer-scale MEMS and semiconductor manufacturing technologies,and the manufacturing yields of the graphene membranes with suspended proof masses were>90%,with>70%of the graphene membranes having>90%graphene area without visible defects.The measured resonance frequencies of the realized structures ranged from tens to hundreds of kHz,with quality factors ranging from 63 to 148.The graphene membranes with suspended proof masses were extremely robust,and were able to withstand indentation forces from an atomic force microscope(AFM)tip of up to~7000nN.The proposed approach for the reliable and large-scale manufacture of graphene membranes with suspended proof masses will enable the development and study of innovative NEMS devices with new functionalities and improved performances.
文摘Cost effective patterning based on scanning probe nanolithography(SPL)has the potential for electronic and optical nano-device manufacturing and other nanotechnological applications.One of the fundamental advantages of SPL is its capability for patterning and imaging employing the same probe.This is achieved with self-sensing and self-actuating cantilevers,also known as‘active'cantilevers.Here we used active cantilevers to demonstrate a novel path towards single digit nanoscale patterning by employing a low energy(<100 eV)electron exposure to thin films of molecular resist.By tuning the electron energies to the lithographically relevant chemical resist transformations,the interaction volumes can be highly localized.This method allows for greater control over spatially confined lithography and enhances sensitivity.We found that at low electron energies,the exposure in ambient conditions required approximately 10 electrons per single calixarene molecule to induce a crosslinking event.The sensitivity was 80-times greater than a classical electron beam exposure at 30 keV.By operating the electro-exposure process in ambient conditions a novel lithographic reaction scheme based on a direct ablation of resist material(positive tone)is presented.
基金This work was financially supported by Science Foundation Ireland(SFI,grant numbers:15/SIRG/3329,12/RC/2278_P2,PI_15/IA/3131)the Irish Research Council(Project 204486,Award 13653)+2 种基金Science Foundation Ireland and the Royal Society Fellowship(URF/RI/191637)The SEM and(S)TEM imaging for this project was carried out at the Advanced Microscopy Laboratory(AML),Trinity College Dublin,Ireland.The AML is an SFI supported imaging and analysis centre,part of the CRANN Institute and affiliated to the AMBER centre.G.S.D and T S-L acknowledge the European Commission under the project Graphene Flagship(Grant No.881603)the German Ministry of Education and Research(BMBF)under ACDC(Grant No.13N15100).
文摘Tungsten ditelluride(WTe_(2))is a layered transition metal dichalcogenide(TMD)that has attracted increasing research inter-est in recent years.WTe_(2) has demonstrated large non-saturating magnetoresistance,potential for spintronic applications and promise as a type-II Weyl semimetal.The majority of works on WTe_(2) have relied on mechanically exfoliated flakes from chemical vapour transport(CVT)-grown crystals for their investigations.While producing high-quality samples,this method is hindered by several disadvantages including long synthesis time,high-temperature annealing and an inherent lack of scalability.In this work,a synthesis method is demonstrated that allows the production of large-area polycrystalline films of WTe_(2).This is achieved by the reaction of pre-deposited films of W and Te at a relatively low temperature of 550℃.Sputter X-ray photoelectron spectroscopy reveals the rapid but self-limiting nature of the oxidation of these WTe_(2) films in ambient conditions.The WTe_(2) films are composed of areas of micrometre-sized nanobelts that can be isolated and offer potential as an alternative to CVT-grown samples.These nanobelts are highly crystalline with low defect densities indicated by transmission electron microscopy and show promising initial electrical results.
文摘In this paper we describe a hybrid system approach for high consumption industrial furnace control. The problem is observed in systematic way starting from the need for modeling this system as hybrid. For description of this behavior we use the Hybrid System Description Language. After that, we design an optimal controller for the furnace and we simulate and compare the controller with other relevant predictive controllers. We have shown that using the hybrid approach for control of industrial furnaces leads to significant improvement of the control system performances.
文摘A novel image reversible data-hiding scheme based on primitive and varying radix numerical model is presented in this article.Using varying radix,variable sum of data may be embedded in various pixels of images.This scheme is made adaptive using the correlation of the neighboring pixels.Messages are embedded as blocks of non-uniform length in the high-frequency regions of the rhombus mean interpolated image.A higher amount of data is embedded in the high-frequency regions and lesser data in the low-frequency regions of the image.The size of the embedded data depends on the statistics of the pixel distribution in the cover image.One of the major issues in reversible data embedding,the location map,is minimized because of the interpolation process.This technique,which is actually LSB matching,embeds only the residuals of modulo radix into the LSBs of each pixel.No attacks on this RDH technique will be able to decode the hidden content in the marked image.The proposed scheme delivers a prominent visual quality despite high embedding capacity.Experimental tests carried out on over 100 natural image data sets and medical images show an improvement in results compared to the existing schemes.Since the algorithm is based on the variable radix number system,it is more resistant to most of the steganographic attacks.The results were compared with a higher embedding capacity of up to 1.5 bpp reversible schemes for parameters like Peak Signal-to-Noise Ratio(PSNR),Embedding Capacity(EC)and Structural Similarity Index Metric(SSIM).
文摘The documents contain a large amount of valuable knowledge on various subjects and, more recently, documents on the Internet are available from various sources. Therefore, automatic, rapid and accurate classification of these documents with less human interaction has become necessary. In this paper, we introduce a new algorithm called the highest repetition of words in a text document (HRWiTD) to classify the automatic Arabic text. The corpus is divided into a train set and a test set to be applied to proposed classification technique. The train set is analyzed for learning and the learning data is stored in the Learning Dataset file. The category that contains the highest repetition for each word is assigned as a category for the word in Learning Dataset file. This file includes non-duplicate words with the value of higher repetition and categories and they get from all texts in the train set. For each text in the test set, the category of words is assigned to a specific category by using Learning Dataset file. The category that contains the largest number of words is assigned as the predicted category of the text. To evaluate the classification accuracy of the HRWiTD algorithm, the confusion matrix method is used. The HRWiTD algorithm has been applied to convergent samples from six categories of Arabic news at SPA (Saudi Press Agency). As a result, the accuracy of the HRWiTD algorithm is 86.84%. In addition, we used the same corpus with the most popular machine learning algorithms which are C5.0, KNN, SVM, NB and C4.5, and their results of classification accuracy are 52.86%, 52.38%, 51.90%, 51.90% and 30%, respectively. Thus, the HRWiTD algorithm gives better classification accuracy compared to the most popular machine learning algorithms on the selected domain.
文摘Detection of liquid mixture of different volume ratio is very important in industrial purposes. The paper reports a sensing mechanism of binary liquid mixture for different volume fraction, based on the measurement of refractive index of the mixture. Here, a highly sensitive liquid filled core Photonic Crystal Fiber structure has been proposed to detect liquid mixture solution. Numerical investigation of the proposed structure is carried out by employing full vectorial Finite Element Method (FEM).
