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Chemical Foaming of Carbon Fiber-Polylactic Acid (CF-PLA) Porous Structures and Their Feasibility as EMI Shields in the X-Band

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IEEE ACCESS 2024年 12卷 78110-78121页

作者： Marrocco, Valeria Surace, Rossella Calo, Giovanna Brandonisio, Elisabetta Marasco, Ilaria Filograno, Francesca Fassi, Irene Natl Res Council Italy CNR Inst Intelligent Ind Technol & Syst Adv Mfg STIIMA I-70124 Bari Italy Politecn Bari Dept Elect & Informat Engn I-70125 Bari Italy Natl Res Council Italy CNR Inst Intelligent Ind Technol & Syst Adv Mfg STIIMA I-20133 Milan Italy

The massive increase in telecommunications infrastructure and devices has recently exacerbated the necessity of developing advanced electromagnetic interference (EMI) shielding solutions. Porous structures based on conductive polymer composites (CPCs) are currently promoted as feasible options for this task. In this scenario, the chemical foaming process shows suitability for easily fabricating CPC foams with closed cells and variable porosity. Nonetheless, the process and the products have not yet been fully explored in the literature for EMI shielding purposes. Hence, this work proposes the fabrication of foams made of polylactic acid with 10wf% carbon fiber (CF-PLA) via chemical foaming. After the process assessment, the morphological and dielectric characterizations of the samples were discussed in the function of the process parameters. The results show that chemical blowing agent (CBA) weight fraction % and temperature were key in obtaining target structural and dielectric requirements enabling EMI shielding. Numerical analyses on CF-PLA foams, modeled according to morphological outcomes, were performed via the integral finite difference time domain (IFDTD) method. The obtained Scattering Parameters and shielding effectiveness (SE), between 0.5 and 12 GHz, highlighted that when foam relative density and air pore density are simultaneously high, the shielding is mainly accomplished through absorption (SER =20 dB) while reflection is minimized (SEA =2 dB). Scattering Parameters and SE were also measured in the X-band showing good agreement with the numerical findings;indeed, CF-PLA foams with higher relative density and air cell density exhibited a reduction of SER (3dB) and a SEA with maxima up to 30dB.

关键词： Electromagnetic interference Chemicals programmable logic arrays Polymers Carbon dioxide Morphology Substrates Electromagnetic fields Absorption Chemical foaming process EMI-shielding carbon fiber polylactic acid foam morphology relative permittivity electromagnetic field absorption shielding effectiveness

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Property Satisfiability Analysis for Product Lines of Modelling Languages

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 2022年第2期48卷 397-416页

作者： Guerra, Esther de Lara, Juan Chechik, Marsha Salay, Rick Univ Autonoma Madrid Modelling & Software Engn Res Grp Madrid 28049 Spain Univ Autonoma Madrid Madrid 28049 Spain Univ Toronto Toronto ON M5S Canada

Software engineering uses models throughout most phases of the development process. Models are defined using modelling languages. To make these languages applicable to a wider set of scenarios and customizable to specific needs, researchers have proposed using product lines to specify modelling language variants. However, there is currently a lack of efficient techniques for ensuring correctness with respect to properties of the models accepted by a set of language variants. This may prevent detecting problematic combinations of language variants that produce undesired effects at the model level. To attack this problem, we first present a classification of instantiability properties for language product lines. Then, we propose a novel approach to lifting the satisfiability checking of model properties of individual language variants, to the product line level. Finally, we report on an implementation of our proposal in the Merlin tool, and demonstrate the efficiency gains of our lifted analysis method compared to an enumerative analysis of each individual language variant.

关键词： Unified modeling language Analytical models Petri nets Syntactics Tools programmable logic arrays Software engineering Model-driven engineering software language engineering product lines meta-modelling OCL model finding

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GRAPH-BASED OUTPUT PHASE ASSIGNMENT FOR PLA MINIMIZATION

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IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS 1995年第5期14卷 613-622页

作者： XU, YB ABDELBARR, M MCCROSKY, C Department of Computational Science University of Saskatchewan Saskatoon Canada

A graph-based approach to finding near-optimal output phase assignments for PLA minimization is presented. A distinctive feature of the approach is that it exploits the necessary and sufficient conditions to reduce the number of product terms needed for PLA implementation and permits the use of existing graph algorithms to solve the PLA output phase optimization problem. The work is based on the transformation of a PLA into a graph whose vertices are the set of conditions required to reduce each product term of the PLA, and whose edges represent the relations between these conditions. Cliques (completely connected subgraphs) in the graph correspond to the output phase assignments required to reduce the product terms represented by the vertices in the cliques. The optimal PLA output phase assignment problem is then formulated as the well-studied problem in graph theory: finding maximum cliques in graphs. Using an existing algorithm for locating cliques in graphs, a modified greedy algorithm is proposed to compute output phase assignments for logic functions in polynomial time. Experimental results using a number of benchmark functions show that the graph-based approach can achieve optimal or near-optimal output phase assignment for PLA minimization and can lead to PLA's with fewer product terms than achieved using existing approaches.

关键词： programmable logic arrays logic functions Greedy algorithms Decoding Sufficient conditions Graph theory Polynomials Minimization methods Circuits

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DFT EXPERT - DESIGNING TESTABLE VLSI CIRCUITS

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IEEE DESIGN & TEST OF COMPUTERS 1989年第5期6卷 8-19页

作者： BHAWMIK, S PALCHAUDHURI, P INDIAN INST TECHNOL DEPT COMP SCIKHARAGPUR 721302W BENGALINDIA

A set of expert-system modules for designing easily testable VLSI circuits called DFT Expert is described. DFT Expert operates at the register-transfer level of circuit description, classifying circuit components into data transporters (DTs) and data processors (DPs). It identifies DPs and DTs, selects a test method, configures global design for test (DFT), and generates test schedules. DFT Expert's ability to test a practical circuit is demonstrated.

关键词： Circuit testing Design for testability Very large scale integration System testing Automatic testing Expert systems logic testing programmable logic arrays Registers Research and development

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A 76-MHZ BICMOS programmable logic SEQUENCER

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 1989年第5期24卷 1287-1294页

作者： SUNG, C SASAKI, PT LEUNG, R CHU, YM LE, KM CONNER, GW LANE, RH DEJONG, JL CLINE, R SIGNET CORP PLD DESIGN GRPSUNNYVALECA 94088 SIGNET CORP DEPT BIPOLAR BICMOS ADV TECHNOL DEVSUNNYVALECA 94088 SIGNET CORP ADV TECHNOL DEV GRPSUNNYVALECA 94088

A BiCMOS programmable logic sequencer with a maximum operating frequency of 76 MHz at a power dissipation of 370 mW has been developed. The device is organized as 16 inputs, 48 product terms, and eight registered outputs. The excellent speed power performance and TTL/CMOS compatibility were realized by an optimized circuit design coupled with an advanced BiCMOS process. The process features 13-GHz bipolar transistors, 1- mu m CMOS, TiW fuses, poly resistors, three-layer metal, and single-layer polycide. Bipolar devices are used in areas that utilize their strengths such as high current drivers, small-signal sensing, and precise current sources. CMOS is used in other areas to conserve layout size and power.< >

关键词： BiCMOS integrated circuits programmable logic arrays programmable logic devices CMOS logic circuits logic devices CMOS process Frequency Power dissipation Design optimization Circuit synthesis

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Development, characterization, and modeling of environmentally friendly open-cell acoustic foams

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POLYMER ENGINEERING AND SCIENCE 2013年第9期53卷 1979-1989页

作者： Mosanenzadeh, Shahrzad Ghaffari Naguib, Hani E. Park, Chul B. Atalla, Noureddine Univ Toronto Dept Mech & Ind Engn Toronto ON Canada Univ Sherbrooke Grp Acoust Vibrat Sherbrooke PQ J1K 2R1 Canada

This study shows the development of new polymeric open-cell foams from polypropylene (PP) and polylactide (PLA) resins with a focus on sound absorption properties and modeling of these foams. The objective is to develop new environmentally friendly foams to replace the existing non-recyclable Polyurethane foams are currently used for sound insulation in industry. Through this research, open-cell foams of about 90% porosity were fabricated from PP and PLA. These resins were selected since PP is a recyclable thermoplastic polymer, and PLA is a bio-based thermoplastic polymer made from renewable resources. Polyurethane (PU) foam which is currently used for sound absorption and noise control in industry was compared to the fabricated PP and PLA foams. As the first attempt to fabricate environmentally friendly acoustic foams, the resulting foam structures show improved properties as compared to the existing materials. The average absorption of PP and PLA foams fabricated is in the range of 0.42-0.55 which is comparable or even higher than the average absorption of PU foam. To better understand the effect of structural and material properties on sound absorption and further improve the acoustic performance of bio-based foams, an analytical model based on Johnson-Champoux-Allard model was used to numerically simulate the acoustic performance of foams under study. POLYM. ENG. SCI., 2013. (c) 2013 Society of Plastics Engineers

关键词： Modeling Acoustics programmable logic arrays thermoplastic polymer polyurethane foam Acoustic wave absorption Foam Cells acoustic insulation open-cell foam Foam Dosage Form Polypropylenes Foam ACOUSTIC PERFORMANCE FOAM STRUCTURE Plutonium

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Reductive Dechlorination of Hexachlorobutadiene by a Pd/Fe Microparticle Suspension in Dissolved LaCtic Acid Polymers: Degradation Mechanism and Kinetics

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2017年第42期56卷 12092-12100页

作者： Rodrigues, Romain Betelu, Stephanie Colombano, Stefan Masselot, Guillaume Tzedakis, Theodore Ignatiadis, Ioannis BRGM French Geol Survey 3 Ave Claude Guillemin F-45060 Orleans 2 France ADEME French Environm & Energy Management Agcy 20 Ave Gresille F-49000 Angers 1 France LGC Chem Engn Lab 118 Route Narbonne F-31062 Toulouse 9 France

Reductive dechlorination of hexachlorobutadiene (HCBD) was performed by a suspension of scattered spots of palladium nanoparticles deposited on iron microparticles (nPd/mu ZVI) in a mixture of dissolved lactic acid polymers and oligomers (referred to as PLA). The effects of nPd/mu ZVI loading, temperature, HCBD initial concentration, and PLA content were investigated as to define the best conditions for the dechlorination. HCBD dechlorination by nPd/mu ZVI occurred in a two-step process: first, HCBD adsorbed onto the nPd surface, which resulted in a rapid initial disappearance of pollutant in solution, and, second, it degraded chemically by atomic hydrogen H*, which resulted from the dissociative adsorption of H-2 on nPd. HCBD remained adsorbed on the surface until its complete degradation in nonchlorinated product, in agreement with the formation of an ordered activated complex on the nPd/mu ZVI surface as suggested by the negative entropy of activation calculated from the Eyring equation. Hence, a minimum amount of nPd/mu ZVI was required to enable simultaneously HCBD adsorption and H-2 production. In these cases, pseudo-first order rate equations were suitable to model HCBD disappearance kinetics. The increase in PLA content resulted in enhancing initial pH decrease such as to maintain acidic conditions and thus high reactivity over a longer period of time. It also resulted in enhancing the contact between HCBD and nPd/mu ZVI, which was characterized by a more important initial adsorption. As a consequence, deviations from pseudo-first order kinetics were observed and a more representative model with a two-phase decay was proposed.

关键词： dechlorination rate equations Reducing Agents hexachlorobutadiene Kinetics lactic acid programmable logic arrays Suspended load

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ON THE HORIZON - FAST CHIPS QUICKLY

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IEEE SPECTRUM 1984年第3期21卷 28-34页

作者： WALLICH, P IEEE Spectrum New York NY USA

A discussion is presented of obstacles on the path toward more sophisticated silicon compilers. An examination is also made of the gap between the ultimate compilers and those now coming into use and the uncertainty over exactly what a silicon compiler is, how compilers work, the various architectural options, and the use of the expert-system approach to design.

关键词： Silicon compiler Humans Layout Silicon Algorithm design and analysis Computer architecture programmable logic arrays

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Mechanical behavior, structure, and reinforcement processes of TEMPO-oxidized cellulose reinforced poly(lactic) acid

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POLYMER COMPOSITES 2013年第2期34卷 173-179页

作者： Bulota, Mindaugas Vesterinen, Arja-Helena Hughes, Mark Seppala, Jukka Aalto Univ Dept Forest Prod Technol Sch Chem Technol FI-00076 Aalto Finland Aalto Univ Sch Chem Technol Dept Biotechnol & Chem Technol FI-00076 Aalto Finland

Poly(lactic) acid (PLA) was reinforced with acetylated TEMPO-oxidized fibrillated cellulose (TOFC) prepared from birch pulp. Composite films were studied using dynamic mechanical thermal analysis, differential scanning calorimetry (DSC), as well as static mechanical testing. The storage modulus as well as tensile strength of PLA was improved on the addition of 30 wt% of TOFC by approximately 50% and 40%, respectively. Thermal stability as well as strength properties in moist environments (up to 90% relative humidity) was significantly improved at 15, 20, 25, and 30 wt% of TOFC. DSC showed that crystallization from solution took place during preparation of the composite films and was much greater than melt crystallization. POLYM. COMPOS., 2012. (C) 2013 Society of Plastics Engineers

关键词： Cellulose programmable logic arrays Crystallization Differential scanning calorimetry Tensile Strength Storage modulus Composite films Trailer on flat car poly(lactic acid) WELLS Mechanical properties Relative Humidity

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Melt Rheological Investigation of Polylactide-Nanographite Platelets Biopolymer Composites

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POLYMER ENGINEERING AND SCIENCE 2014年第1期54卷 175-188页

作者： Narimissa, Esmaeil Gupta, Rahul K. Kao, Nhol Choi, Hyoung J. Jollands, Margaret Bhattacharya, Sati N. RMIT Univ RMPC Sch Civil Environm & Chem Engn Melbourne Vic 3000 Australia Inha Univ Dept Polymer Sci & Engn Inchon 402751 South Korea

This study is an analytical investigation of processability of biopolymer-carbon based nanofiller composites primarily through rheological investigation of samples. The composites were fabricated via dry mixing and melt-blending of biodegradable polylactide (PLA) and nanographite platelets (NGP) in a Brabender twin screw extruder. A range of different nanofiller contents (1, 3, 5, 7, and 10 wt %) were studied for NGP containing composites. The morphology was studied with X-ray diffraction and transmission electron microscopy techniques and showed poor dispersion, with agglomerates, tactoids, and exfoliated layers present. Mechanical properties showed an optimum at 3 wt % filler. Results showed that the composites exhibited higher elastic and viscous moduli than neat PLA. The rheological percolation threshold predicted by changes in slope () as well as liquid-solid transition theory of samples was found around 3 wt % through the change from liquid-like behavior to pseudo-solid-like behavior at terminal region during dynamic oscillatory measurements. NGP nanofillers were found to enhance the viscoelastic and mechanical properties of PLA at low concentrations;however, an efficient dispersion of nanofillers within polymer by melt intercalation method of mixing was not achieved. POLYM. ENG. SCI., 54:175-188, 2014. (c) 2013 Society of Plastics Engineers

关键词： Composites programmable logic arrays NORTH GALACTIC POLE dry mixing Blood Platelets Transmission electron microscopy NANOFILLER Biopolymers Mechanical properties

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