bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneous Biocatalysts for the Final Stages of Deep Processing of Renewable Resources into Valuable Products
Authors: Kovalenko Galina , Perminova Larisa
Published: December 2020

Heterogeneous biocatalysis is a part of biotechnology and it has commercial potential for industrial implementation, in particular the final stages of deep processing of renewable raw materials. The commercially attractive heterogeneous biocatalysts are prepared by immobilizing practically valuable enzymatic active substances onto solid inorganic supports. Heterogeneous biocatalytic processes of the target conversion of substrate into valuable market product are carried out in periodic or continuous modes using traditional batch and packed-bed reactors, as well as novel types of vortex reactors in accordance with the principles of green chemistry. Heterogeneous biocatalysts for the final stages of deep processing of vegetable raw materials such as starch and oils are described here. One of the biocatalysts is glucoamylase immobilized by adsorption on mesoporous carbon support Sibunit™ type. This glucoamylase-active biocatalyst is used at the stage of starch saccharification, i.e., hydrolysis of dextrin to treacle and glucose syrups used in food and confectionary industries. The second of the biocatalysts is recombinant T. lanuginosus lipase immobilized on mesoporous silica KSK™ type and macroporous carbon aerogel. These lipase-active biocatalysts can effectively compete with traditional organic synthesis catalysts, and they are used in low-temperature processes carried out in unconventional anhydrous media such as interesterification of vegetable oils’ triglycerides with ethyl acetate for producing ethyl esters of fatty acids (biodiesel and vitamin F) and esterification of fatty acids with aliphatic alcohols for synthesis of various esters used as fragrances, flavorings, odors, emollients, and nonionic surfactants in perfume and cosmetics industries. The prepared heterogeneous biocatalysts due to their high enzymatic activity and operational stability are promising for practical implementation.
Designing River Diversion Constructed Wetland for Water Quality Improvement
Authors: Dauda Ahmed Sani , Kwaku Agodzo Sampson , Amaning Adjei Kwaku
Published: December 2020

Constructed wetlands are recognized as viable potential technology for reducing pollution load and improving quality of water and wastewater. The use of river diversion wetlands is gaining place for improving quality of river and stream water. However, the design criterion for this category of wetlands has not been fully established, and there is a need to optimize existing approach to enhance operational performance. This chapter presents a step-by-step approach for the design of a typical river diversion constructed wetland intended to remove some pollutants and improve river water quality. The approach focused mainly on water quality objective and outlined simple criteria, guidelines, and model equations for the design procedure of a new river diversion constructed wetland. The design of constructed wetlands is generally an iterative process based on empirical equations. Thus, this approach combines simple equations and procedure for estimating the amount of river water to be diverted for treatment so as to assist the designer in sizing the wetland system. The novel approach presented may be useful to wetland experts as some of the procedures presented are not popular in wetland studies. However, this may improve existing river diversion wetlands’ design and development.
Aerogels Utilization in Electrochemical Capacitors
Authors: Sudhakar Ranganatha
Published: December 2020

Supercapacitors are the integral part of electrochemical energy conversion and storage media. Energy storage mechanism is different in supercapacitors compared to batteries and results in exhibition of excellent power density. The supercapacitor performance is sensitive to material used as electrode, nature of electrolyte, etc. and the very significant is electrode surface nature. Based on the type of energy storage mechanism, supercapacitors are divided as electrochemical double-layer capacitors and pseudocapacitors. There is a practice to have both kind of these materials as electrode materials to achieve high electrochemical performance. Aerogels with inherent characteristics such as large pores, very high surface area, and superior mechanical stability make them superior candidates for electrode materials for high performance electrochemical supercapacitors. In this chapter, aerogels derived from different sources, their suitability and performance in view of electrochemical supercapacitors are discussed.
Defects Assessment in Subsea Pipelines by Risk Criteria
Authors: Lepikhin Anatoly , Leschenko Victor , Makhutov Nikolay
Published: December 2020

Subsea inter-field pipelines are an important element of offshore oil and gas infrastructure. Leakage or fracture of these pipelines is associated with the risk of large economic and environmental losses. One of the main sources of pipeline fracture is pipe defects. The presented section discusses the methodological aspects of assessing the hazard of defects of subsea inter-field pipelines by risk criteria of accidents. A conceptual approach of defects hazard assessing by risk criteria has been formulated, based on analysis the requirement of modern standards. The risk is defined as the probability of negative consequences, the scale of which is determined by the hazard class of pipeline accidents. The probability and scale of accidents are linked by a risk matrix. A method for a three-level assessment of the suitability of a pipeline for operation after in-line inspection has been developed. The method allows assessing the hazard of the most typical defects in subsea pipelines, such as metal loss, metal delamination, cracks and crack-like defects. The allowable defect sizes are determined for the given risk criteria using partial safety factors. The novelty of the methodology lies in the substantiation of safety factors according to risk criteria corresponding to a given class of damage and loss. A scheme for making decisions on the admissibility of defects by risk criteria has been developed. An example of hazard assessment of defects in subsea pipelines is presented.
The Novel Nanomaterials Based Biosensors and Their Applications
Authors: Gençdağ Şensoy Kübra , Muti Mihrican
Published: December 2020

Since the development of the first biosensor reported, biosensor has received considerable attention due to its high selectivity and sensitivity. Biosensors are highly pursued in order to meet the growing demands and challenges in a large number of analytic applications such as medical diagnosis, food safety control, environmental monitoring, or even military defense. Due to the unique physical, chemical, mechanical and electrical properties, nanomaterials have been widely investigated for their ability and used to fabricate sensors. High surface to volume ratio, good stability, excellent electrocatalytic properties of the nanomaterials plays an important role in the sensitive and selective detection of biomolecules. The synthesis of new nanomaterials with different properties is increasingly common in order to improve these counted properties of nanomaterials. This chapter gives an overview of the importance of the development of novel nanomaterials based biosensors technologies. The use of different funtionalized carbon nanomaterilas, metal oxide nanoparticles, metal nanoparticles, polymeric nanoparticles, quantum dots, graphene sheets and other novel nanomaterials in biosensor technology, and their innovations and advantages are discussed.
Entrepreneurial Momentum for Sustainable Growth
Authors: Katernyak Ihor , Loboda Viktoriya
Published: December 2020

Public and private sectors view entrepreneurship as a movement of active, creative people who exploit opportunities under uncertainty, create new products, jobs, contribute to economic development of region. Entrepreneurs with their ‘fresh’ vision and agility play an important role in creating the sustainable future for all by overcoming social and environmental challenges. Based on real cases, we illustrate the path travelled by entrepreneurs from identifying the problem and creating the platform for communication with stakeholders to building solution and scaleup. We demonstrate our ‘4A engine’ approach to maintain the momentum for startup consisting of 4 phases: Attention, Actualisation, Attraction, and Action. Even if the start is successful, statistics show that many startups fail between 18 and 24 months. Therefore, we ask startup founders about their practice and biggest surprise they came across, essential choices and important decisions they made. Readers who find this practice useful will reflect by writing a Letter from the Future.
Environmental Impacts of Heavy Metals and Their Bioremediation
Authors: Handan Dökmeci Ayşe
Published: December 2020

Fast consumption, increasing energy needs, unplanned urbanization, and unconscious discharge of industrial wastes cause pollution of air, soil, food and water resources. Among these pollutants, heavy metals and metalloids are not biodegradable and accumulate in compartments such as water, soil and plants, threatening human and environmental health. Monitoring studies show that heavy metals such as arsenic, lead, mercury, cadmium, nickel, zinc, copper, chromium and trace elements are in first place according to their availability in the environment. Preventive and remedial measures should be taken to reduce the effects of heavy metals. Legal regulations, monitoring studies, the use of soluble and non-toxic compounds in environmental compartments (air, water, soil and plants) in industrial processes, heavy metal-free pesticides, appropriate wastewater treatment plants and use of renewable energy sources instead of fossil fuels are among the priority measures to reduce concentrations of heavy metals in the environment. As a bioremediation approach, removing toxic wastes from the environment by using bioaccumulatory organisms such as plants or mussels maintains its importance among studies aimed at recovery. Studies have shown that integrated methods - especially the combination of suitable plants and microorganisms - are very effective in mitigating the effect of heavy metals in the environment.
San Jerónimo en la onomástica de la familia Martí de Torres-Aguilar y su proyección en el retablo cuatrocentista de San Martín, del Museo de Bellas Artes de Valencia
Authors: Rubio Vela Agustín
Published: December 2020

Resumen: El estudio de la onomástica familiar de los Martí de Torres-Aguilar, comitentes del retablo cuatrocentista de San Martín, santa Úrsula y san Antonio abad, obra señera del gótico valenciano, y el análisis iconográfico de sus tablas principales, obligan a poner en duda la identificación tradicional de san Antonio abad como el representado en ellas. Tanto la onomástica como la tradición iconográfica apuntan a que la figura en cuestión corresponde a san Jerónimo.Paraules clau: siglo XV, Valencia, San Jerónimo, Martí de Torres, AguilarAbstract: We have studied the family onomastics of the Martí de Torres-Aguilar,  who commissioned the 15th-century raredos St Martin, St Ursula and St Anthony Abbot, a prominent piece of the Valencian gothic. This study, and the iconographic analysis of its main panels, beg the question whether the represented saint can actually be St Anthony Abbot. Both the onomastics and the iconographic tradition suggest that this figure should be matched to St Jerome.Keywords: 15th century, Valencia, St Jerome, Martí de Torres, Aguilar
La lenta segregación de los conventos de Navarra de la dominicana Provincia de Aragón culminada en 1569
Authors: Esponera Cerdán Alfonso
Published: December 2020

Resumen: Desde su establecimiento en 1300, la dominicana Provincia de Aragón la fueron configurando los conventos de los Reinos de Aragón, Valencia, Navarra, Mallorca y el Principado de Cataluña con la Cerdaña y el Rosellón, Cerdeña y Sicilia. Si bien la conquista e incorporación del Reino de Navarra a Castilla fue en 1512, no ocurrió lo mismo con los conventos dominicanos navarros que después de diversos intentos de la Corona, sólo culminó su incorporación a la Provincia de España en 1569. Esta segregación ha sido un tema escasamente estudiado por los historiadores y es el que se analiza en este trabajo.    Palabras clave: dominicos,  Provincia de Aragón, Corona de Castilla, siglo XVAbstract: Since its establishment in 1300, the Dominican Province of Aragon was configured by the convents of the Kingdoms of Aragon, Valencia, Navarra, Mallorca and the Principality of Catalonia (with the Cerdanya and Roussillon), Sardinia and Sicily. Although the conquest and incorporation of the Kingdom of Navarre into Castile was in 1512 not happened the same with the Dominican convents of Navarre, that only after several attempts of the Crown culminated its incorporation into the Province of Spain in 1569. This segregation has been a topic rarely studied by historians and is the main topic of this paper.  .Keywords: dominicans,  Province of Aragon, Crown of Castile, 15th siecle
Els bandos de Valènsia o la paraula de sen Vicent Ferrer (1855): el primer milacre de Vicent Boix
Authors: Fuertes Zapata Juan Vicente
Published: December 2020

Resum: Un dels primers autors de milacres amb nom i cognoms coneguts, va ser el cronista de València, Vicent Boix i Ricarte (1813-1880). Aquella activitat seua va ser esporàdica, però és molt possible que el seu inici es puga situar el 1855, data del quart centenar de la canonització del sant. En aquella celebració, a més, Boix va ser l’encarregat d’elaborar el llibre commemoratiu i, d’aquell any és la publicació de la seua obreta Els bandos de Valènsia o la paraula de sen Vicent Ferrer, que analitzem en aquest article.Paraules clau: Vicent Boix, milacres, treatre valencià, segle XIXAbstract: One of the first authors of milacres with name and surname known, was the historian of Valencia, Vicent Boix i Ricarte (1813-1880). That activity was sporadic, but it is very possible that its beginning can be placed on 1855, date of the fourth centenary of the canonization of St. Vicente Ferrer. In that celebration, in addition, Boix was the one in charge to elaborate the commemorative book and of that year it is the publication of Els bandos de Valènsia o la paraula de sen Vicent Ferrer, that analyzes in this article.Keywords: Vicent Boix, milacres, valencian theatre, 19th. century
El cos de la dona maltractada sota l’escrutini mèdic: els casos de València i Lleida en la baixa edat mitjana
Authors: Ferragud Carmel , Roca Guillem
Published: December 2020

Resum: A partir dels rics fons en matèria judicial que es conserven als arxius de les ciutats de València i Lleida, hem desenvolupat una recerca sobre la intervenció dels practicants de la medicina com a guaridors i com a experts cridats en els tribunals per determinar la naturalesa i la gravetat de les lesions causades per diferents formes de violència exercida contra la dona: violació, maltractament domèstic, tortura, agressions comunes. Fem una aproximació a la legislació, i la contrastem amb la documentació, particularment els testimonis d’individus cridats als judicis. A més, analitzem el paper de l’expert, com és utilitzat pel jutge, les limitacions de la seua aportació i les controvèrsies que suscita. Això en un marc social on la dona pateix moltes agressions enfront de les quals es veu indefensa, que sovint no es denuncien i on sempre parteix amb desavantatge.Paraules clau: medicina forense, maltractament a dones, tribunals de justícia, edat mitjanaAbstract: Based on the rich judicial sources preserved in the archives from the cities of Valencia and Lleida, we have undertaken a study about the intervention of medical practitioners as healers and experts in the courts of law to determine the nature and gravity of the injuries caused by different means of violence against women: rape, domestic abuse, torture, common assault. We examine the legislation and we compare it with the documentation, namely the testimonies of people who were brought to trial. Yet, we thoroughly analyse the role of the experts, how the judges used the information received from them, the limits of their contribution and the controversy they used to arouse. These situations took place in a setting where women suffered lots of injuries to which they could not defend, and those were hardly ever reported. In brief, women were discriminated by the law.Keywords:  forensic medicine, violence against women, courts of law, Midlle Ages
Oltre il canone nazionale. Le voci che parlano in catalano
Authors: Cataldi Pietro
Published: December 2020

Riassunto: Nella nuova Europa della generazione, o delle generazioni, Erasmus, in questa Europa che vogliamo cosmopolita, ci aspetta il racconto di una letteratura meno parziale, meno sottomessa al principio egemonico degli stati-nazione, una letteratura che ci permetta di recuperare, soprattutto, le voci forti ed emozionanti di autori che il fiume del processo storico ha lasciato in un’ansa laterale, dove piccole comunità hanno potuto continuare a coltivarne e proteggerne la memoria, non senza il rischio di partecipare, con la loro cura identitaria, al processo di esclusione dal canone internazionale. Potremo, anche, guardare per la prima volta, o per la prima volta con adeguata consapevolezza e rispetto, verso letterature emarginate e minorizzate come quella, in lingua catalana. Sappiamo quali faticose vicende storiche ne abbiano segnato la marginalizzazione, fino alla persecuzione franchista, ma proporrei di abbandonare questo punto di vista –che rischia di bloccarci in un gesto di rivendicazione ancora subalterna– a favore di una prospettiva che, se davvero vorrà essere inclusiva e accogliente, dovrà assumersi la responsabilità di essere capace di collocarsi nel presente. Paraules clau: Letteratura catalana, studi del canone letterario, confini sovranazionali, ricezioneAbstract: In the new Europe of the generation, or generations, Erasmus, in this Europe that we want cosmopolitan, awaits us the story of a less partial literature, less subject to the hegemonic principle of nation-states, a literature that allows us to recover, above all, the strong and exciting voices of authors that the river of the historical process has left on one of its sides, where small communities have been able to continue to cultivate and protect their memory, not without the risk of participating, with their identity care, in the process of exclusion from the international canon. For the first time we also will be able to look with adequate awareness and respect at marginalized and minority literatures like the one in the Catalan language. We know what difficult historical events have marked its marginalization, up to the Franco persecution, but I would propose to abandon this point of view –which risks blocking us in a gesture of still subordinate claim- in favor of a perspective that, if it really wants to be inclusive and welcoming, will have to assume the responsibility of being able to place itself in the present. Keywords: Catalan literature, studies of the literary canon, supranational boundaries, reception
Ressenya a Glòria Sabaté Marín, Més enllà de la cort: els lectors potencials del «Curial e Güelfa», Alacant, Universitat d’Alacant, 2019
Authors: Soler Abel
Published: December 2020

Ressenya a Glòria Sabaté i Marín, Més enllà de la cort: els lectors potencials del «Curial e Güelfa», Alacant: Universitat d’Alacant, 2019, 226 pp.,-ISBN: 978-84-09-08273-5
Review to Glòria Sabaté i Marín, Més enllà de la cort: els lectors potencials del «Curial e Güelfa», Alacant: Universitat d’Alacant, 2019, 226 pp.,-ISBN: 978-84-09-08273-5
Early Jurassic (Sinemurian) gastropods from the Lusitanian Basin (west of Portugal)
Authors: Vitón Íñigo , Comas-Rengifo María José , Ricardo Paredes Ricardo
Published: December 2020

The Sinemurian gastropod specimens herein studied come from two sources: from museum collections and from samplings in field. The study of the Sinemurian gastropod specimens housed in the collections of the Museu Geológico (Laboratório Nacional de Energia e Geologia), Museu Nacional de História Natural e da Ciência (University of Lisbon), Museu da Ciência (University of Coimbra) and of the Museu de História Natural e da Ciência (University of Porto), has allowed the systematic and taxonomical update of this material. These specimens come mostly from Sinemurian outcrops in S. Pedro de Moel area and Coimbra region. The review of these collections permitted to recognise original material that was used to describe several characteristic species of the Lusitanian Basin, namely Scurriopsis (Scurriopsis) schmidti, Cryptaenia sp., Nerinella ficalhoi, and Boehmiola exilis. The most common species are endemic of the Lusitanian Basin, namely Pseudomelania costae Pictet & Campiche, 1862 and Oonia casta Böhm, 1901. Other species are known in Germany,Luxembourg and Austria basins.
Presencia de estructuras excepcionalmente preservadas en vías aéreas de Panochthus Burmeister (Xenarthra, Glyptodontidae) del Pleistoceno tardío de Argentina
Authors: Zamorano Martín
Published: December 2020

En esta contribución se presentan materiales excepcionalmente preservados correspondientes a las zonas laríngea y traqueal de las vías aéreas de gliptodóntidos (Xenarthra; Cingulata): dos de la zona laríngea, el cartílago tiroides (MPLK 0004) y el cartílago cricoides (MHM-P 87), y una de la zona traqueal, fragmentos de los anillos traqueales (MHM-P 87). Todos estos cartílagos están osificados y proceden del Pleistoceno tardío de Buenos Aires (Argentina). A su vez, se reconstruyen los músculos que involucran a los cartílagos mencionados. El material de estudio corresponde a dos especímenes, ambos previamente atribuidos a Panochthus sp. Panochthus Burmeister es uno de los Glyptodontidae más frecuentes y diversificados del Pleistoceno de América del Sur. El cartílago tiroides tiene una sección transversal en forma de U, en la porción anterior están las carillas para el hueso impar y en la posterior las carillas donde contacta el cricoide. Los 20 fragmentos de anillos traqueales principalmente varían entre 19 y 54 mm de largo y entre 6 y 8 mm de ancho. El cartílago cricoides tiene forma similar a la de un anillo traqueal, aunque es de mayor tamaño. La relación de tamaño entre los cartílagos estudiados verifica que las proporciones son las mismas que en otros xenartros. Las rugosidades en la lámina lateral del cartílago tiroides permiten concluir que la inserción del músculo cricotiroides es importante y el último cartílago se desplaza significativamente hacia el cráneo. Estudios como este generarán nuevos conocimientos sobre la paleobiología de la megafauna sudamericana.
First functional morphology comparison between two Miocene cricetid mandibles
Authors: Carro-Rodríguez Patricia María , López-Guerrero Paloma , Prieto Jérôme , Álvarez-Sierra María Ángeles , Peláez-Campomanes Pablo
Published: December 2020

Geometric morphometric allows characterizing complex morphologies in order to quantify the geometry of the structure and facilitate comparisons. It allows performing methods analysing differentiation pattern based on variance, such as the Principal Component Analysis (PCA). For that reason, it has been chosen as the method to analyse the mandibles of two extinct species of cricetids rodents: Cricetodon aff. aureus and Megacricetodon minor from the MN6, middle Miocene from Goldberg and Steinberg (Germany). We performed a digitisation of 18 landmarks that resumes the most relevant characteristics of these mandibles. We also performed a measure of the mechanical advantage and potential of the mandibles. In that way, we have been able to quantify notorious morphological differences on the angular and condylar processes and the lower masseter insertion and establish significant differences among the biomechanical behaviour of the mandibles. Later, we can relate the morphological and biomechanical information with speed and force biting.
Inferences of dietary preferences of Miocene squirrels (Xerinae, Sciuridae) from the Iberian Peninsula and Namibia using microwear analyses and enamel thickness
Authors: Menéndez Iris , Gómez Cano Ana R. , Blanco Fernando , Hernández Fernández Manuel , Álvarez-Sierra María A. , Oliver Adriana
Published: December 2020

In this work, we compared microwear features and enamel thickness from upper molars (M1 and M2) of extinct Xerinae squirrels from the Miocene of Namibia (Vulcanisciurus sp) and the Iberian Peninsula (Atlantoxerus nov. sp. and Heteroxerus rubricati). We also examined the microwear from young and adult specimens of one extant squirrel, Atlantoxerus getulus, to compare it with the extinct species. Both, the microwear features and enamel thickness showed that the Miocene African species presented a more abrasive diet than the Iberian ones.
Early Aptian corals from Peñascal (Bilbao, N Spain)
Authors: Löser Hannes , Mendicoa Jone , Fernández-Mendiola Pedro Ángel
Published: December 2020

From two horizons in the lower Aptian Peñascal limestone Formation south of Bilbao 22 coral species are reported. The corals belong to the scleractinian families Actinastraeidae, Eugyridae, Haplaraeidae, Latomeandridae, and Solenocoeniidae, and the octocorallian family Helioporidae. The stratigraphic distribution of the species lies between the Berriasian to Cenomanian, but most species have a distribution between the Barremian and Albian. The faunas show most palaeobiogeographical relationship to faunas from the Hauterivian to Albian of the European Boreal, the Western Atlantic and the Western Tethys.
Representações midiáticas da saúde
Authors: Sacramento Igor , Borges Wilson Couto
Published: December 2020

Para o campo de estudos sobre saúde, vem sendo cada vez mais importante refletir sobre o lugar que a mídia ocupa nas configurações de representações de saúde e doenças, bem como dos indivíduos saudáveis e doentes, dos corpos e das práticas corporais, dos modelos de prevenção e de promoção, dos processos de medicalização, dos fatores de risco e dos pânicos sanitários. As representações são parte de práticas sociais mais amplas que nos localizam, nos identificam, nos diferenciam, nos conectam e nos afastam. É nesse âmbito que os autores, com este livro, buscam estimular estudos sobre as representações midiáticas sobre processos de saúde e doença. A percepção dos autores, dessa forma, é a de que as representações midiáticas têm, sem dúvidas, efeitos profundos em todos as formas de organização da vida social, até mesmo na produção e reprodução de identidades, diferenças, afecções, moralidades, empatias, repulsas e pânicos. As consequências e o poder das representações são intensos, uma vez que elas se tornam campos de batalha para lutas pelo sentido nas sociedades, no interior das quais se disputa estabelecer o que é considerado aceitável, indizível, punível, normal, patológico, saudável, belo e assim por diante.
Adaptive compressive sensing toward low signal-to-noise ratio scene
Authors: Wen Fang-Qing  , Zhang Gong  , Tao Yu  , Liu Su  , Feng Jun-Jie  ,   College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;,   Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

As an alternative paradigm to the Shannon-Nyquist sampling theorem, compressive sensing enables sparse signals to be acquired by sub-Nyquist analog-to-digital converters thus may launch a revolution in signal collection, transmission and processing. In the practical compressive sensing applications, the sparse signal is always affected by noise and interference, and therefore the recovery performance reduces based on the conventional compressive sensing, especially in the low signal-to-noise scene, the sparse recovery is usually unavailable. In this paper, the influence of noise on recovery performance is analyzed, so as to provide the theoretical basis for the noise folding phenomenon in compressive sensing. From the analysis, we find that the expected noise gain in the random measure process is closely related to the row and column of the measurement matrix. However, only those columns corresponding to the support for the sparse signal contribute to the sparse vector. In the traditional Shannon-Nyquist sampling system, an antialiasing filter is applied before the sampling process, so as to filter the noise beyond the passband of interest. Inspired by the necessity of antialiasing filtering in bandpass signal sampling, we propose a selective measurement scheme, namely adapted compressive sensing, whose measurement matrix can be updated according to the noise information fed back by the processing center. The measurement matrix is specially designed, and the sensing matrix has directivity so that the signal noise can be suppressed. The measurement matrix senses only the spectrum of interest, where the sparse spectrum is most likely to lie. Moreover, we compare the recovery performance of the proposed adaptive scheme with those of the non-adaptive orthogonal matching pursuit algorithm, FOCal underdetermined system solver algorithm, and sarse Bayesian learning algorithm. Extensive numerical experiments show that the proposed scheme has a better improvement in the performance of the sparse signal recovery. From the viewpoint of implementation, the measurement noise should be taken into consideration in the system, and more efficient algorithms will be developed for source pre-estimation at lower signal-to-noise ratio.
Theoretical study of the microwave air breakdown at dielectric surface
Authors: Zhou Qian-Hong  , Dong Ye  , Dong Zhi-Wei  , Zhou Hai-Jing  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;,   Science and Technology on High Power Microwave Laboratory, Mianyang 621900, China
Published: December 2020

Microwave air breakdown at dielectric surface is investigated by numerically solving the fluid-based plasma equations coupled with the Maxwell equations. The plasma formation and microwave scattering and absorption by plasma are investigated by one-dimensional (1D) and two-dimensional (2D) models. In the 1D model, it is found that at the initial stage of microwave breakdown, the plasma develops in the whole plasma region. As time increases, the plasma in the upstream grows much faster than in the downstream. Although the electron density distributions for ne = 0 and j = 0 are different, the microwave reflection, absorption and transmission are almost the same. It is found that the electron number density in the upstream region for 20 mm is larger than for 5 mm. In the 2D model, it is found for TE10 mode that the plasmoid first grows in the middle of waveguide until its density becomes large enough to diffract the incident field, then the plasma region moves along the surface to both sides. The plasma region cannot reach the wall of waveguide, where the electric field is smaller than the breakdown threshold. After comparison between the computational and experimental results, it is found that the simulated absorbed power is larger than the measured one, and the transmitted power is smaller than than measured one. The reason is that the initial electron densities in 1D and 2D simulation are both assumed to cover the whole dielectric surface, but the plasma in experiment develops in a very small region.
Pressure-induced structural transition and thermodynamic properties of NbSi2 from first-principles calculations
Authors: Pu Chun-Ying  , Wang Li  , Lü Lin-Xia  , Yu Rong-Mei  , He Chao-Zheng  , Lu Zhi-Wen  , Zhou Da-Wei  ,   College of Physics and Electronic Engineering, Nanyang Nomal University, Nanyang 473061, China
Published: December 2020

Applying the particle swarm optimization algorithm to the crystal structure prediction, we first predict a novel high pressure phase of NbSi2 with Si tetrahedron embedded diamond structure of Nb. NbSi2 alloy undergoes a first-order phase transition from hexagonal phase to cubic phase at about 175 GPa with a volume collapse of 4.1%, indicating the first-order transition. New predicted NbSi2 phase is dynamically stable in the absence of any imaginary phonon frequency in the whole Brillouin zone of phonon spectrum. The calculations of total and partial density of states indicate that the NbSi2 is in hexagonal phase at 0 GPa and it is in cubic structure at 180 GPa, both of which exhibit metal behaviors, which is dominated by Nb atom. There exists obviously the p-d hybridization between Nb and Si, and more charges accumulate in Si tetrahedron. Based on the “stress-strain” method, elastic constants, bulk modulus, shear modulus, Young's modulus, and Debye temperature of NbSi2 in two phases under pressure are systematically investigated using first principles calculations combined with the quasi-harmonic Debye model. To evaluate the ductile and brittle characteristics of NbSi2 alloy, pressure dependence of G/B ratio is investigated. Furthermore, the values of hardness and percent anisotropy AB and AG and the universal anisotropic index AU (inset) for NbSi2 alloy in hexagonal and cubic structures are also calculated. Our results show that external pressure has different effects on the values of ductility and hardness and anisotropy of the two phases. External pressure can improve the ductility of hexagonal phase, while it has a negligible effect on that of cubic phase. The hardness values of two phases of NbSi2 are analyzed in detail by using the G/B ratio. As pressure increases, the elastic anisotropy of hexagonal phase increases rapidly, while that of cubic phase remains unchanged.
Theoretical and experimental investigations on wavefront distortion and thermal-stress induced birefringence in a laser diode pumped helium gas-cooled multislab Nd:glass laser amplifier
Authors: Huang Wen-Fa  , Li Xue-Chun  , Wang Jiang-Feng  , Lu Xing-Hua  , Zhang Yu-Qi  , Fan Wei  , Lin Zun-Qi  ,   National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

Thermal effect is still the most serious problem: it restricts the high power and high beam quality of solid laser to be further enhanced. The efficient thermal management is an important approach to suppress the thermal effect. In this paper, the thermal effect in a gas-cooled laser diode pumped multislab Nd:glass amplifier operating at a repetition rate is investigated in detail both theoretically and experimentally. The three-dimensional distributions of temperature, stress, strain, and birefringence are calculated by a finite element analysis. Based on these data, the thermally induced wavefront distortions and depolarization losses are determined with considering six slabs and one laser head. It is revealed that the theoretical data are in good agreement with the experimental results: the total wavefront distortion is 6.77 and a depolarization loss of more than 90% accumulates over six slabs when the heat deposition is 0.7 W/cm3.
Robust control for permanent magnet synchronous motors based on Hamiltonian function
Authors: Wu Zhong-Qiang  , Wu Chang-Han  , Zhao Li-Ru  , Jia Wen-Jing  ,   Key Lab of Industrial Computer Control Engineering of Hebei Province, College of Electric Engineering, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

Hamiltonian system theory is an important reflearch tool for nonlinear systems, and has been widely used in motor speed regulation and control during reflent years. Aiming at the chaotic phenomenon in permanent magnet synchronous motors, a design method of robust controller based on the Hamiltonian function is preflented for the chaotic systems. The dynamic model of permanent magnet synchronous motor is transformed into a model similar to the Lorenz chaotic equation, and the model is chaotic at certain parameters according to the Lyapunov exponent and the Lyapunov dimension calculated. Let the rotator speed of the motor track a set of values, an error equation is obtained accordingly. Because the error equation does not satisfy the standard form of Hamilton exactly, it can be transformed into the Hamiltonian system containing uncertain disturbance terms. While the uncertain disturbance terms as well as the load term are regarded as a total disturbance term to the system, a kind of robust controller is designed. The controller consists of two parts. One part is based on the method of interconnection and damping assignment, and can make the rotator speed track any value well; The other part is used as a disturbance compensator. Simulation result shows that the controller drives the permanent magnet synchronous motor out of the chaotic state rapidly and the rotator speed tracks the set of values well. It is proven that the controller is feasible and effective. The method mentioned in this paper extends the range of application of Hamiltonian function and has a certain advantage.
Study on transmission characteristics of dark solitons in inhomogeneous optical fibers
Authors: Pan Nan  , Huang Ping  , Huang Long-Gang  , Lei Ming  , Liu Wen-Jun  ,   State Key Laboratory of Information Photonics and Optical Communications, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The terms of gain(or absorption), dispersion, and nonlinearity in the nonlinear Schrödinger equation are usually variables, which can be used to study the propagation of optical pulses in inhomogeneous optical fibers. In this paper, with the aid of the Hirota method, the bilinear forms of the Schrödinger equation are derived. Based on the bilinear form, the analytic dark soliton solutions to the nonlinear Schrödinger equation are obtained. The properties of dark solitons are discussed. Stable dark solitons are observed in the normal dispersion regime. In addition, corresponding parameters for controlling the propagation of dark solitons are analyzed. Results of our reflearch show that the propagation route of solitons can be effectively controlled by the gain(or absorption), dispersion, and nonlinearity, which can improve the quality of signal transmission in optical communications. When the amplitude of the loss coefficient increases, the amplitude of the dark soliton increases suddenly during the transmission process.By means of changing the type of dispersion, the purpose of controlling the dark soliton phase and phase oscillation is achieved. The possibly applicable soliton control techniques, which are used to design dispersion and nonlinearity-managed systems, are proposed. The proposed techniques may find applications in soliton management communication links, like soliton control.In addition, two-soliton solution is obtained. With the dark two-soliton solution, the interaction between two solitons is discussed in the paper. The result may be of potential application in the ultralarge capacity transmission systems.
Effect of Al doping on the reliability of HfO2 as a trapping layer: First-principles study
Authors: Jiang Xian-Wei  , Dai Guang-Zhen  , Lu Shi-Bin  , Wang Jia-Yu  , Dai Yue-Hua  , Chen Jun-Ning  ,   Anhui Provincial Key Lab of Integrated Circuit Design, School of Electronics and Information Engineering, Anhui University, Hefei 230601, China;,   School of Electronics and Information Engineering, Hefei Normal University, Hefei 230061, China
Published: December 2020

In this work, the first-principles method based on materials studio(a soft ware) and the density functional theory is used to invesigate the properties of charge reflention and charge endurance in HfO2 as a trapping layer in charge trapping memory (CTM). Two supercell models are optimized for the monoclinic HfO2, separately. One contains a four-fold-coordinated O vacancy defect (VO4), and the other is a co-doped composite defect consisting of a VO4 and an Al atom. Interaction energies, formation energies, Bader charge, density of states and trapping energy are calculated for the two models. According to the calculated results of interaction energies and formation energies, it is found that the structure is the most stable and the defect is the most easily formed when the distance between the two kinds of defects is of 2.216 in the co-doped composite defect system. The trapping energy results show that the co-doped composite defect system can trap both electrons and holes. Moreover, the trapping ability of the co-doped composite defect is enhanced significantly as compared with the VO4 defect. Bader charge analysis shows that the co-doped composite defect system provides a more preflerable site for the charge reflention. Calculations of the density of states show that the co-doped composite defect system has a strong effect on the trapping energy of holes. Calculated energy changes after program/erase cycles show that the endurance is improved obviously in the co-doped composite defect system. In conclusion, the date reflention and endurance in the trapping layer of monoclinic HfO2 can be improved by doping of the substitutional impurity Al. This work may provide a theoretical guidance for performance improvement with respect to the date reflention and endurance of CTM.
Research progress of super-continuum terahertz source based on nano-structures and terahertz lab on-chip system
Authors: Zuo Jian  , Zhang Liang-Liang  , Gong Chen  , Zhang Cun-Lin  ,   Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

The terahertz applications of bio-materials and energetic materials are hindered by the low power-intensity of the terahertz output and the narrow band of terahertz emission. So the crucial part of the development of terahertz time-domain spectroscopy (TDS) systems is the new terahertz source with broadband frequency range and high power output. As to the free-space TDS system, the system is necessarily purged by dried nitrogen gas to remove the absorbed water vapor. In addition, the low detection sensitivity also exists because of the free-space interactions between the terahertz emission and the substances. To address these problems, terahertz lab on-chip system is proposed. The local field effect in the nano-structures of on-chip system can contribute to the detection of low concentration of the substance. The present paper is composed of two sections. Firstly, a new terahertz source based on the metal nano-film can produce an intense and broad-band terahertz-infrared emission, which is comprised of incoherent terahertz-infrared signals and coherent terahertz signals. This emission can cover more than 100 THz and has an output power of up to 10 mW. This optical phenomenon mainly arises from the incoherent thermal radiation effect. Secondly, the terahertz lab on-chip systems with different transmission lines and different substrates are clarified. There exists lower loss on the on-chip system with coplanar stripline structure and copolymer substrate. High sensitivity of biological detection in terahertz band of up to 2 THz can be achieved by using this system.
Atmospheric polarization pattern simulation for small solar elevation angles and the analysis of atmospheric effect
Authors: Hu Shuai  , Gao Tai-Chang  , Li Hao  , Cheng Tian-Ji  , Liu Lei  , Huang Wei  , Jiang Shi-Yang  ,   College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101 China
Published: December 2020

To simulate the atmospheric polarization pattern for small solar elevation angle, we develop a the vector radiative transfer model VSPART (vector pseudo-spherical radiative transfer model considering refraction), and use it to calculate the polarization state of downwelling diffuse light. In this model, the propagation trajectory, transmittance rate and polarization states of directly transmitted light are tracked by ray-tracing method for spherical refractive atmosphere. Based on the matrix algorithm, an improved method to solve the radiative transfer equation is proposed. Output of this model includes not only the Stokes vector and degree of polarization of diffuse light, but also the polarized irradiance. The precision of VSPART is validated against the benchmark results, literature results and SPDISORT, and excellent agreement is achieved. DOP (degree of polarization) and AOP (angle of polarization) are simulated for pure Rayleigh scattering atmosphere and atmosphere with aerosol, and the characteristics of their angular distributions are analyzed. In addition, the influences of atmospheric spherical geometry and refraction effect on the sky DOP are discussed as well. Simulation results show that for low solar elevation angle, with the increasing of wavelength, DOP increases gradually, and the Arago and Babinet neutral points move towards the horizon when Rayleigh scattering atmosphere is considered. Although the existence of aerosol does not change the basic distribution of DOP, it has a significant influence on AOP. With the increasing of aerosol optical depth, DOP decreases gradually, and the distribution of AOP changes dramatically. By comparing the sky distribution of DOP, it could also be concluded that the neutral points might arise from low order scattering. The area affected by atmospheric spherical geometry and atmospheric refraction effect mainly includes the area near horizontal directions, the area near the neutral points and the area perpendicular to the ground. For pure Rayleigh scattering atmosphere, the influence is reduced with the increasing of the wavelength of incident light, especially for the areas near the neutral points, where the influence gradually disappears as wavelength increases. For atmosphere with aerosol, with their optical depth increasing, the effects of atmospheric spherical geometry and atmospheric refraction are gradually enhanced.