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Phytic acid-lignin combination: A simple and efficient route for enhancing thermal and flame retardant properties of polylactide

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EUROPEAN POLYMER JOURNAL 2017年 94卷 270-285页

作者： Costes, Lucie Laoutid, Fouad Brohez, Sylvain Delvosalle, Christian Dubois, Philippe Univ Mons UMONS Mat Nova Res Ctr Lab Polymer & Composite Mat Pl Parc 23 B-7000 Mons Belgium Univ Mons UMONS Fac Polytech Serv Genie Procedes Chim Pl Parc 23 B-7000 Mons Belgium

Lignin and phytic acid combinations were used as a simple route for developing bio-based flame retardant systems in PLA. The composites were prepared by melt blending and their mechanical, thermal and fire properties have been explored. Combining these two additives has been shown to present an interesting way of limiting the negative effect of each of them and for improving the properties of the resulting materials. On the first hand, the presence of phytic acid enables better dispersion of lignin particles into the matrix, limiting PLA thermal degradation induced by lignin. On the second hand, lignin enables important reduction of the composite hygroscopy induced by the presence of phytic acid. Moreover, combining lignin and phytic acid leads to significant reduction up to 44% of peak of heat release rate (pHRR) during cone calorimeter test as well as obtaining V-2 classification in UL-94 test. Some positive effects of the binary combinations on the composites mechanical properties have also been evidenced (increase of the elongation at break from 3.1% to 12.6% for one formulation).

关键词： programmable logic arrays Fire Retardants Polylactides Routes Lignin

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Physical-Layer Authentication Based on Hierarchical Variational Autoencoder for Industrial Internet of Things

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IEEE INTERNET OF THINGS JOURNAL 2023年第3期10卷 2528-2544页

作者： Meng, Rui Xu, Xiaodong Wang, Bizhu Sun, Hao Xia, Shida Han, Shujun Zhang, Ping Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China Peng Cheng Lab Dept Broadband Commun Shenzhen 518066 Peoples R China Peng Cheng Lab Dept Knowledge Network Shenzhen 518066 Peoples R China Univ Cambridge Dept Appl Math & Theoret Phys Cambridge CB2 1TN England Beijing Univ Posts & Telecommun Natl Engn Lab Mobile Network Technol Beijing 100876 Peoples R China China Acad Informat & Commun Technol Technol & Stand Res Inst Beijing 100191 Peoples R China

Recently, physical-layer authentication (PLA) has attracted much attention since it takes advantage of the channel randomness nature of transmission media to achieve communication confidentiality and authentication. In the complex environment, such as the Industrial Internet of Things (IIoT), machine learning (ML) is widely employed with PLA to extract and analyze complex channel characteristics for identity authentication. However, most PLA schemes for IIoT require attackers' prior channel information, leading to severe performance degradation when the source of the received signals is unknown in the training stage. Thus, a channel impulse response (CIR)-based PLA scheme named "hierarchical variational autoencoder (HVAE) " for IIoT is proposed in this article, aiming at achieving high authentication performance without knowing attackers' prior channel information even when trained on a few data in the complex environment. HVAE consists of an autoencoder (AE) module for CIR characteristics extraction and a variational AE (VAE) module for improving the representation ability of the CIR characteristic and outputting the authentication results. Besides, a new objective function is constructed in which both the single-peak and the double-peak Gaussian distributions are taken into consideration in the VAE module. Moreover, the simulations are conducted under the static and mobile IIoT scenario, which verify the superiority of the proposed HVAE over three comparison PLA schemes even with a few training data.

关键词： programmable logic arrays Authentication Industrial Internet of Things Wireless communication Communication system security Servers Neural networks Autoencoder (AE) Industrial Internet of Things (IIoT) physical-layer authentication (PLA) unsupervised learning (UL)

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Bessel Beam Generation Using Dielectric Planar Lenses at Millimeter Frequencies

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IEEE ACCESS 2020年 8卷 216185-216196页

作者： Vaquero, Alvaro F. Rodriguez Pino, Marcos Arrebola, Manuel Matos, Sergio A. Costa, Jorge R. Fernandes, Carlos A. Univ Oviedo Dept Elect Engn Grp Signal Theory & Commun Gijon 33202 Spain Univ Lisbon Inst Super Tecn Inst Telecomunicacoes P-1049001 Lisbon Portugal Inst Univ Lisboa ISCTE IUL Dept Ciencias & Tecnol Informacao P-1649026 Lisbon Portugal

In this work a dielectric planar lens is proposed to generate a Bessel beam. The lens works at Ka-band and produces a non-diffraction range within the Fresnel region of the antenna. The methodology to design the aperture antenna at millimetre or microwave frequencies is presented. It is applied to a dielectric planar lens made up of cells that shapes the radiated near-field by adjusting the unit cell response. An approach based on a second order polynomial is proposed to consider the angular dependence of the phase-shift response of the cell in the designing process. In order to implement the lens physically, two novel cells, based on rectangular and hexagonal prisms, are proposed, and their performance is compared. The cells ensure the index dielectric media variation using airgaps to control the overall density of the material. After fully characterizing the cells, a design is carried out for the two proposed type of cells. The requirement for the Bessel beam is a depth-of-field of 650 mm at 28 GHz. After evaluating the design in a full-wave simulation, both prototypes were manufactured using a 3-D printing technique. Finally, the prototypes were measured in a planar acquisition range to evaluate the performances of the Bessel beam. Both lenses show a good agreement between simulations and measurements, obtaining promising results in the Bessel beam generation by index-graded dielectric lenses at Ka-band.

关键词： Lenses Indexes Finite element analysis Dielectric constant programmable logic arrays Media Diffraction Dielectric lenses Bessel beams near-field focusing

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Distributed Physical Layer Authentication: Overview and Opportunities

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IEEE COMMUNICATIONS MAGAZINE 2024年第1期62卷 134-140页

作者： Zhang, Tianhui Huo, Yan Ma, Liran Guo, Ela Beijing Jiaotong Univ Beijing Peoples R China Texas Christian Univ Ft Worth TX USA

Distributed physical layer authentication (DPLA) is a novel authentication framework, which not only exploits the collaborative computing of multiple devices to enhance overall efficiency, but also alleviates the degradation of processing performance caused by resource-constrained terminals. It is considered a promising architecture for solving access security issues in future communications. Considering DPLA's potential, in this article, we review existing DPLA schemes to provide a comprehensive summary of the strategies and technical approaches adopted during each implementation stage. Our simulation results show that the voting-assisted DPLA scheme has better authentication performance than the centralized PLA. In addition, we also present some open research issues on DPLA, addressing new opportunities ahead and potential research directions.

关键词： Authentication programmable logic arrays Physical layer Peer-to-peer computing Collaboration Training Wireless sensor networks Distributed management

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EASILY TESTABLE PLA-BASED FINITE STATE MACHINES

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IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS 1990年第6期9卷 604-611页

作者： DEVADAS, S MA, HKT Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA

An outline is presented of a synthesis procedure that, beginning from a state transition graph (STG) description of a sequential machine, produces an optimized easily testable programmable logic array (PLA) based logic implementation. Previous approaches to synthesizing easily testable sequential machines have concentrated on the stuck-at-fault model; for PLAs, an extended fault model called the crosspoint fault model has been used. The authors propose a procedure of constrained state assignment and logic optimization which guarantees testability for all combinationally irredundant crosspoint faults in a PLA-based finite-state machine. No direct access to the flip-flops is required. The test sequences to detect these faults can be obtained using combinational test generation techniques alone. This procedure thus represents an alternative to a scan design methodology. Results are presented which show that the area/performance penalties in return for easy testability are small.< >

关键词： Automata Circuit testing Circuit faults logic testing programmable logic arrays Sequential analysis Sequential circuits Circuit synthesis programmable logic devices logic design

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Confidentiality-Preserving Edge-Based Wireless Communications for Contact Tracing Systems

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2022年第11期40卷 3152-3171页

作者： Xie, Ning Wang, Wenya Chen, Yicong Zhang, Peichang Huang, Lei Shenzhen Univ Coll Elect & Informat Engn Guangdong Key Lab Intelligent Informat Proc Shenzhen 518060 Peoples R China Shenzhen Univ Coll Elect & Informat Engn Guangdong Engn Res Ctr Posit Sensing & Detect Shenzhen 518060 Peoples R China

This paper addresses two issues of a contact-tracing system with edge-based wireless communication techniques: to locate close contacts and to provide confidentiality-preserving communications. In this paper, we propose the Confidentiality-Preserving Contact-Tracing (CPCT) system with multiple wireless edge-based nodes. The CPCT system consists of three stages: registration, authentication, and confidentiality-preserving communication stages. We propose two Physical-Layer Authentication (PLA) schemes for the authentication stage of the CPCT system: the Coordinate-based Location PLA (CLP) scheme using the estimated coordinates and the Time-of-Arrival (ToA) based Location PLA (TLP) scheme using the estimated ToAs. We propose a distributed encryption scheme for the confidentiality-preserving communication stage of the CPCT system named the Distributed Channel Impulse Response (CIR)-based Encryption (DCE) scheme. We provide the theoretical analysis of the proposed schemes and derive their closed-form expressions. We implement the proposed schemes and conduct extensive performance comparisons through simulations. We observe that the theoretical results perfectly match the corresponding simulation results. Moreover, the proposed PLA schemes provide higher authentication performance than the prior PLA scheme, while the proposed encryption scheme provides higher confidentiality performance than the prior encryption scheme.

关键词： programmable logic arrays Wireless communication Authentication Encryption Monitoring Communication system security Wireless fidelity Physical layer authentication time of arrival contact tracing authentication performance confidentiality

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Enhanced Film Blowing of Polylactide by Incorporating Branched Chains and Stereocomplex Crystals

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INTERNATIONAL POLYMER PROCESSING 2015年第4期30卷 500-510页

作者： Nouri, S. Lafleur, P. G. Dubois, C. Ecole Polytech Dept Chem Engn CREPEC Montreal PQ H3C 3A7 Canada

Chain architecture is an influential parameter in melt processing of polymeric material. In this study effect of different chain structures on polylactide (PLA) film blowing process and on the final film properties was investigated. Blends of linear PLA with three branched poly(L-lactide)s with 4-arms star shaped, comb like and hyper branched structures were prepared by twin screw extruder. In another series of blending, poly(D-lactide) of these branched structures were used to obtain stereocomplex crystal. Operating window of blends were determined in a series of film blowing process experiments with different blow up and take up ratio and results were compared to linear PLA as a reference. Moreover, different characterization techniques were applied to determine the properties of produced films. It was found that addition of branched architecture and presence of stereocomplex in a linear PLA matrix result in a greater operating window for film blowing and improve mechanical and crystallization properties of blown films.

关键词： MELT PROCESSING series (mathematics) programmable logic arrays FILM PROPERTY Blends Polylactides Plastics-Blow molding branches polymeric materials

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OPTIMIZATION OF ONE-BIT FULL ADDERS EMBEDDED IN REGULAR STRUCTURES

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND SIGNAL PROCESSING 1986年第5期34卷 1289-1300页

作者： IWANO, K STEIGLITZ, K Department of Computer Science Princeton University Princeton NJ USA

We study the problem of optimizing the transistor sizes in the one-bit nMOS full adder either isolated or embedded in a regular array. A local optimization method that we call the critical-path optimization method is developed. In this method, two parameters at a time are changed along the critical path until a locally optimal choice of transistor sizes is found. The critical-path optimization method uses the Berkeley VLSI tools and the hierarchical layout language ALLENDE developed at Princeton. First, we optimize the isolated one-bit full adder implemented in three ways: as a PLA, data selector, and with random logic. The details of the critical-path optimization method and power-time tradeoff curves are illustrated here. Second, we optimize the one-bit full adder embedded in a simple array multiplier. The entire 3 × 3, 4 × 4, 8 × 8, and 10 × 10 multipliers are optimized and their local optima are compared. Because the optimization of the entire circuit becomes less practical when the circuit becomes larger, we develop a method that makes use of circuit regularity. We prove that some small array of one-bit full adders, called the canonical configuration, has the same local optima as the n × n multiplier for large n, with the criterion of minimizing the delay time T. Hence, we can greatly reduce the computation load by optimizing this canonical configuration instead of optimizing the entire circuit. Experimental results confirm the effectiveness of this approach.

关键词： Adders Optimization methods Circuits MOS devices Very large scale integration programmable logic arrays Delay effects Digital signal processing chips Throughput Finite impulse response filter

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Mechanical Properties, Morphologies and Thermal Decomposition Kinetics of Poly(lactic acid) Toughened by Waste Rubber Powder

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INTERNATIONAL POLYMER PROCESSING 2015年第4期30卷 467-475页

作者： Yang, J. -N. Nie, S. -B. Ding, G. -X. Wang, Z. -F. Gao, J. -S. Zhu, J. -B. Anhui Univ Sci & Technol Sch Mat Sci & Engn Huainan 232001 Peoples R China Anhui Univ Sci & Technol Sch Min & Safety Engn Huainan 232001 Peoples R China

To improve the impact resistance and reduce the product cost, poly(lactic acid) (PLA) blends containing varying mass fraction of waste rubber powder (WRP) were fabricated via melt compounding. The effects of WRP contents on the mechanical properties, morphologies and thermal stabilities of PLA/WRP blends were investigated. Mechanical tests showed that WRP could increase the ductilities of PLA, leading to the significant improvements in the impact toughness and elongation at break. In contrast, the tensile strength was just heightened slightly, while elastic modulus declined gradually. Scanning electron microscopy observations indicated that well bonded interfacial morphologies were formed between PLA and WRP. From the results of thermo gravimetric analysis, WRP decreased the onset and peak decomposition temperatures of PLA phase and increased the char contents of samples significantly. Average activation energies of samples were increased first and then decreased with increasing WRP. Finally, theoretical lifetimes of PLA/WRP blends were also estimated.

关键词： poly(lactic acid) Thermal decomposition kinetics SRGAP3 gene impact resistance Mechanical properties Elongation at break programmable logic arrays Decomposition kinetics rubber waste Mechanical testing IMPACT TOUGHNESS

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HEURISTIC MINIMIZATION OF MULTIPLE-VALUED RELATIONS

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IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS 1993年第10期12卷 1458-1472页

作者： WATANABE, Y BRAYTON, RK Department of Electrical Engineering and Computer Science University of California Berkeley CA USA

A multiple-valued relation is a relation between inputs and outputs in which the input variables can assume more than two discrete values. Multiple-valued relations arise quite naturally in many contexts. Using characteristic functions to represent relations, we can handle the problem of minimizing multiple-valued relations as a generalization of the conventional minimization problem of regular logic functions. Our approach is based on a state-of-the-art paradigm for the two level minimization of functions. We clarify some special properties of relations, in contrast to functions, which must be carefully considered in realizing a high quality procedure for solving the minimization problem. An efficient heuristic method to find an optimal sum-of-products representation for a multiple-valued relation is proposed and implemented in the program GYOCRO. It uses multiple-valued decision diagrams (MDD's) to represent the characteristic functions for the relations. Experimental results are presented and compared with previous exact and heuristic Boolean relation minimizers to demonstrate the effectiveness of the proposed method.

关键词： programmable logic arrays Input variables Minimization logic functions Boolean functions logic design Automata Cost function

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