We present a novel formulation, based on the latest advancement in polynomial system solving via linear algebra, for identifying limit cycles in general n-dimensional autonomous nonlinear polynomial systems. The condi...We present a novel formulation, based on the latest advancement in polynomial system solving via linear algebra, for identifying limit cycles in general n-dimensional autonomous nonlinear polynomial systems. The condition for the existence of an algebraic limit cycle is first set up and cast into a Macaulay matrix format whereby polynomials are regarded as coefficient vectors of monomials. This results in a system of polynomial equations whose roots are solved through the null space of another Macaulay matrix. This two-level Macaulay matrix approach relies solely on linear algebra and eigenvalue computation with robust numerical implementation. Furthermore, a state immersion technique further enlarges the scope to cover also non-polynomial (including exponential and logarithmic) limit cycles. Application examples are given to demonstrate the efficacy of the proposed framework.展开更多
Facial imaging is a term used to describe methods that use facial images to assist or facili-tate human identification. This pertains to two craniofacial identification procedures that use skulls and faces—facial app...Facial imaging is a term used to describe methods that use facial images to assist or facili-tate human identification. This pertains to two craniofacial identification procedures that use skulls and faces—facial approximation and photographic superimposition—as well as face-only methods for age progression/regression, the construction of facial graphics from eye-witness memory (including composites and artistic sketches), facial depiction, face mapping and newly emerging methods of molecular photofitting. Given the breadth of these facial imaging techniques, it is not surprising that a broad array of subject-matter experts partici-pate in and/or contribute to the formulation and implementation of these methods (includ-ing forensic odontologists, forensic artists, police officers, electrical engineers, anatomists, geneticists, medical image specialists, psychologists, computer graphic programmers and software developers). As they are concerned with the physical characteristics of humans, each of these facial imaging areas also falls in the domain of physical anthropology, although not all of them have been traditionally regarded as such. This too offers useful opportunities to adapt established methods in one domain to others more traditionally held to be disciplines within physical anthropology (e.g. facial approximation, craniofacial super-imposition and face photo-comparison). It is important to note that most facial imaging methods are not currently used for identification but serve to assist authorities in narrowing or directing investigations such that other, more potent, methods of identification can be used (e.g. DNA). Few, if any, facial imaging approaches can be considered honed end-stage scientific methods, with major opportunities for physical anthropologists to make meaningful contributions. Some facial imaging methods have considerably stronger scientific underpin-nings than others (e.g. facial approximation versus face mapping), some currently lie entirely within the artistic sphere (facial depiction), and yet others are so aspirational that realistic capacity to obtain their aims has strongly been questioned despite highly advanced tech-nical approaches (molecular photofitting). All this makes for a broad-ranging, dynamic and energetic field that is in a constant state of flux. This manuscript provides a theoretical snap-shot of the purposes of these methods, the state of science as it pertains to them, and their latest research developments.展开更多
In this paper, we propose a new lightweight block cipher named RECTANGLE. The main idea of the design of RECTANGLE is to allow lightweight and fast implementations using bit-slice techniques. RECTANGLE uses an SP-netw...In this paper, we propose a new lightweight block cipher named RECTANGLE. The main idea of the design of RECTANGLE is to allow lightweight and fast implementations using bit-slice techniques. RECTANGLE uses an SP-network. The substitution layer consists of 16 4 × 4 S-boxes in parallel. The permutation layer is composed of 3 rotations. As shown in this paper, RECTANGLE offers great performance in both hardware and software environment, which provides enough flexibility for different application scenario. The following are3 main advantages of RECTANGLE. First, RECTANGLE is extremely hardware-friendly. For the 80-bit key version, a one-cycle-per-round parallel implementation only needs 1600 gates for a throughput of 246 Kbits/s at100 k Hz clock and an energy efficiency of 3.0 p J/bit. Second, RECTANGLE achieves a very competitive software speed among the existing lightweight block ciphers due to its bit-slice style. Using 128-bit SSE instructions,a bit-slice implementation of RECTANGLE reaches an average encryption speed of about 3.9 cycles/byte for messages around 3000 bytes. Last but not least, we propose new design criteria for the RECTANGLE S-box.Due to our careful selection of the S-box and the asymmetric design of the permutation layer, RECTANGLE achieves a very good security-performance tradeoff. Our extensive and deep security analysis shows that the highest number of rounds that we can attack, is 18(out of 25).展开更多
Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color render...Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narrowband QDs.However,the red QDs in these studies were cadmium-based,which is a restricted element in the EU and certain other countries.The use of InP-based QDs,the most promising Cd-free alternative,is often presented as an inferior solution because of the broader linewidth of these QDs.However,while narrow emission lines are the key to display applications that require a large color gamut,the spectral efficiency penalty of this broader emission is limited for lighting applications.Here,we report efficient,high-CRI white LEDs with an on-chip color converter coating based on red InP/ZnSe QDs and traditional green/yellow powder phosphors.Using InP/ZnSe QDs with a quantum yield of nearly 80% and a full width at half-maximum of 45 nm,we demonstrate high spectral efficiency for white LEDs with very high CRI values.One of the best experimental results in terms of both luminous efficacy and color rendering performance is a white LED with an efficacy of 132 lm/W,and color rendering indices of R_(a)≈90,R9 ≈50 for CCT ≈4000 K.These experimental results are critically compared with theoretical benchmark values for white LEDs with on-chip downconversion from both phosphors and red Cd-based QDs.The various loss mechanisms in the investigated white LEDs are quantified with an accurate simulation model,and the main impediments to an even higher efficacy are identified as the blue LED wall-plug Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narrowband QDs.However,the red QDs in these studies were cadmium-based,which is a restricted element in the EU and certain other countries.The use of In P-based QDs,the most promising Cd-free alternative,is often presented as an inferior solution because of the broader linewidth of these QDs.However,while narrow emission lines are the key to display applications that require a large color gamut,the spectral efficiency penalty of this broader emission is limited for lighting applications.Here,we report efficient,high-CRI white LEDs with an on-chip color converter coating based on red In P/Zn Se QDs and traditional green/yellow powder phosphors.Using In P/Zn Se QDs with a quantum yield of nearly 80% and a full width at half-maximum of 45 nm,we demonstrate high spectral efficiency for white LEDs with very high CRI values.One of the best experimental results in terms of both luminous efficacy and color rendering performance is a white LED with an efficacy of 132 lm/W,and color rendering indices of Ra≈ 90,R9 ≈ 50 for CCT ≈ 4000 K.These experimental results are critically compared with theoretical benchmark values for white LEDs with on-chip downconversion from both phosphors and red Cd-based QDs.The various loss mechanisms in the investigated white LEDs are quantified with an accurate simulation model,and the main impediments to an even higher efficacy are identified as the blue LED wall-plug efficiency and light recycling in the LED package.展开更多
The emergence of space-time modulated metasurface(STMM)as a novel platform for signal modulation holds significant promise for wireless secure communication,particularly within modern information technologies such as ...The emergence of space-time modulated metasurface(STMM)as a novel platform for signal modulation holds significant promise for wireless secure communication,particularly within modern information technologies such as Internet of things and the 5th generation and beyond.While previous secure communication methods based on STMM have primarily focused on ensuring information security within both the time and frequency domains,in this study,we introduce a novel code domain modulation scheme in STMM to facilitate wireless secure communications,which is difficult to be detected in both time and frequency domains.The core concept involves synthesizing a smart modulation waveform by using a new code domain so that both secure information transmission and mitigation of jamming are realized.To achieve this,we build a Q-dimensional signal space that has a minimum overlap with the jamming signal space and where orthogonal or quasi-orthogonal basis functions are used for information transmission.Furthermore,this methodology can be readily extended to other abstract signal domains.To exemplify this approach,we implement an STMM and utilize it to transmit the logos of our universities accurately,while eavesdroppers are unable to acquire any useful information through direct identification from the constellation diagrams.This showcases the effectiveness of the proposed secure communication system.展开更多
Multicomponent alloys show intricate microstructure evolution,providing materials engineers with a nearly inexhaustible variety of solutions to enhance material properties.Multicomponent microstructure evolution simul...Multicomponent alloys show intricate microstructure evolution,providing materials engineers with a nearly inexhaustible variety of solutions to enhance material properties.Multicomponent microstructure evolution simulations are indispensable to exploit these opportunities.These simulations,however,require the handling of high-dimensional and prohibitively large data sets of thermodynamic quantities,of which the size grows exponentially with the number of elements in the alloy,making it virtually impossible to handle the effects of four or more elements.In this paper,we introduce the use of tensor completion for highdimensional data sets in materials science as a general and elegant solution to this problem.We show that we can obtain an accurate representation of the composition dependence of high-dimensional thermodynamic quantities,and that the decomposed tensor representation can be evaluated very efficiently in microstructure simulations.This realization enables true multicomponent thermodynamic and microstructure modeling for alloy design.展开更多
文摘We present a novel formulation, based on the latest advancement in polynomial system solving via linear algebra, for identifying limit cycles in general n-dimensional autonomous nonlinear polynomial systems. The condition for the existence of an algebraic limit cycle is first set up and cast into a Macaulay matrix format whereby polynomials are regarded as coefficient vectors of monomials. This results in a system of polynomial equations whose roots are solved through the null space of another Macaulay matrix. This two-level Macaulay matrix approach relies solely on linear algebra and eigenvalue computation with robust numerical implementation. Furthermore, a state immersion technique further enlarges the scope to cover also non-polynomial (including exponential and logarithmic) limit cycles. Application examples are given to demonstrate the efficacy of the proposed framework.
文摘Facial imaging is a term used to describe methods that use facial images to assist or facili-tate human identification. This pertains to two craniofacial identification procedures that use skulls and faces—facial approximation and photographic superimposition—as well as face-only methods for age progression/regression, the construction of facial graphics from eye-witness memory (including composites and artistic sketches), facial depiction, face mapping and newly emerging methods of molecular photofitting. Given the breadth of these facial imaging techniques, it is not surprising that a broad array of subject-matter experts partici-pate in and/or contribute to the formulation and implementation of these methods (includ-ing forensic odontologists, forensic artists, police officers, electrical engineers, anatomists, geneticists, medical image specialists, psychologists, computer graphic programmers and software developers). As they are concerned with the physical characteristics of humans, each of these facial imaging areas also falls in the domain of physical anthropology, although not all of them have been traditionally regarded as such. This too offers useful opportunities to adapt established methods in one domain to others more traditionally held to be disciplines within physical anthropology (e.g. facial approximation, craniofacial super-imposition and face photo-comparison). It is important to note that most facial imaging methods are not currently used for identification but serve to assist authorities in narrowing or directing investigations such that other, more potent, methods of identification can be used (e.g. DNA). Few, if any, facial imaging approaches can be considered honed end-stage scientific methods, with major opportunities for physical anthropologists to make meaningful contributions. Some facial imaging methods have considerably stronger scientific underpin-nings than others (e.g. facial approximation versus face mapping), some currently lie entirely within the artistic sphere (facial depiction), and yet others are so aspirational that realistic capacity to obtain their aims has strongly been questioned despite highly advanced tech-nical approaches (molecular photofitting). All this makes for a broad-ranging, dynamic and energetic field that is in a constant state of flux. This manuscript provides a theoretical snap-shot of the purposes of these methods, the state of science as it pertains to them, and their latest research developments.
基金supported by National Natural Science Foundation of China(Grant No.61379138)Research Fund KU Leuven(OT/13/071)+1 种基金"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No.XDA06010701)National High-tech R&D Program of China(863 Program)(Grant No.2013AA014002)
文摘In this paper, we propose a new lightweight block cipher named RECTANGLE. The main idea of the design of RECTANGLE is to allow lightweight and fast implementations using bit-slice techniques. RECTANGLE uses an SP-network. The substitution layer consists of 16 4 × 4 S-boxes in parallel. The permutation layer is composed of 3 rotations. As shown in this paper, RECTANGLE offers great performance in both hardware and software environment, which provides enough flexibility for different application scenario. The following are3 main advantages of RECTANGLE. First, RECTANGLE is extremely hardware-friendly. For the 80-bit key version, a one-cycle-per-round parallel implementation only needs 1600 gates for a throughput of 246 Kbits/s at100 k Hz clock and an energy efficiency of 3.0 p J/bit. Second, RECTANGLE achieves a very competitive software speed among the existing lightweight block ciphers due to its bit-slice style. Using 128-bit SSE instructions,a bit-slice implementation of RECTANGLE reaches an average encryption speed of about 3.9 cycles/byte for messages around 3000 bytes. Last but not least, we propose new design criteria for the RECTANGLE S-box.Due to our careful selection of the S-box and the asymmetric design of the permutation layer, RECTANGLE achieves a very good security-performance tradeoff. Our extensive and deep security analysis shows that the highest number of rounds that we can attack, is 18(out of 25).
文摘Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narrowband QDs.However,the red QDs in these studies were cadmium-based,which is a restricted element in the EU and certain other countries.The use of InP-based QDs,the most promising Cd-free alternative,is often presented as an inferior solution because of the broader linewidth of these QDs.However,while narrow emission lines are the key to display applications that require a large color gamut,the spectral efficiency penalty of this broader emission is limited for lighting applications.Here,we report efficient,high-CRI white LEDs with an on-chip color converter coating based on red InP/ZnSe QDs and traditional green/yellow powder phosphors.Using InP/ZnSe QDs with a quantum yield of nearly 80% and a full width at half-maximum of 45 nm,we demonstrate high spectral efficiency for white LEDs with very high CRI values.One of the best experimental results in terms of both luminous efficacy and color rendering performance is a white LED with an efficacy of 132 lm/W,and color rendering indices of R_(a)≈90,R9 ≈50 for CCT ≈4000 K.These experimental results are critically compared with theoretical benchmark values for white LEDs with on-chip downconversion from both phosphors and red Cd-based QDs.The various loss mechanisms in the investigated white LEDs are quantified with an accurate simulation model,and the main impediments to an even higher efficacy are identified as the blue LED wall-plug Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narrowband QDs.However,the red QDs in these studies were cadmium-based,which is a restricted element in the EU and certain other countries.The use of In P-based QDs,the most promising Cd-free alternative,is often presented as an inferior solution because of the broader linewidth of these QDs.However,while narrow emission lines are the key to display applications that require a large color gamut,the spectral efficiency penalty of this broader emission is limited for lighting applications.Here,we report efficient,high-CRI white LEDs with an on-chip color converter coating based on red In P/Zn Se QDs and traditional green/yellow powder phosphors.Using In P/Zn Se QDs with a quantum yield of nearly 80% and a full width at half-maximum of 45 nm,we demonstrate high spectral efficiency for white LEDs with very high CRI values.One of the best experimental results in terms of both luminous efficacy and color rendering performance is a white LED with an efficacy of 132 lm/W,and color rendering indices of Ra≈ 90,R9 ≈ 50 for CCT ≈ 4000 K.These experimental results are critically compared with theoretical benchmark values for white LEDs with on-chip downconversion from both phosphors and red Cd-based QDs.The various loss mechanisms in the investigated white LEDs are quantified with an accurate simulation model,and the main impediments to an even higher efficacy are identified as the blue LED wall-plug efficiency and light recycling in the LED package.
基金National Natural Science Foundation of China(Grant Nos.62222108 and 32261133623)China Scholarship Council(Grant No.202306840004).
文摘The emergence of space-time modulated metasurface(STMM)as a novel platform for signal modulation holds significant promise for wireless secure communication,particularly within modern information technologies such as Internet of things and the 5th generation and beyond.While previous secure communication methods based on STMM have primarily focused on ensuring information security within both the time and frequency domains,in this study,we introduce a novel code domain modulation scheme in STMM to facilitate wireless secure communications,which is difficult to be detected in both time and frequency domains.The core concept involves synthesizing a smart modulation waveform by using a new code domain so that both secure information transmission and mitigation of jamming are realized.To achieve this,we build a Q-dimensional signal space that has a minimum overlap with the jamming signal space and where orthogonal or quasi-orthogonal basis functions are used for information transmission.Furthermore,this methodology can be readily extended to other abstract signal domains.To exemplify this approach,we implement an STMM and utilize it to transmit the logos of our universities accurately,while eavesdroppers are unable to acquire any useful information through direct identification from the constellation diagrams.This showcases the effectiveness of the proposed secure communication system.
基金This work is supported by:(1)European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(INTERDIFFUSION,grant agreement no 714754)(2)Fonds de la Recherche Scientifique-FNRS and the Fonds Wetenschappelijk Onderzoek-Vlaanderen under EOS Project no 30468160(SeLMA)+1 种基金(3)European Research Council under the European Union’s Seventh Framework Programme(FP7/2007-2013)/ERC Advanced Grant:BIOTENSORS(no.339804)(4)KU Leuven Internal Funds(C16/15/059).(5)KU Leuven Internal Funds(PDM/18/146).
文摘Multicomponent alloys show intricate microstructure evolution,providing materials engineers with a nearly inexhaustible variety of solutions to enhance material properties.Multicomponent microstructure evolution simulations are indispensable to exploit these opportunities.These simulations,however,require the handling of high-dimensional and prohibitively large data sets of thermodynamic quantities,of which the size grows exponentially with the number of elements in the alloy,making it virtually impossible to handle the effects of four or more elements.In this paper,we introduce the use of tensor completion for highdimensional data sets in materials science as a general and elegant solution to this problem.We show that we can obtain an accurate representation of the composition dependence of high-dimensional thermodynamic quantities,and that the decomposed tensor representation can be evaluated very efficiently in microstructure simulations.This realization enables true multicomponent thermodynamic and microstructure modeling for alloy design.
