bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementación de un sistema para evaluar la cobertura de la red sigfox en el interior de edificaciones
Authors: Egas Acosta Carlos , Revelo Vizcaino Eduardo
Published: November 2022

Las redes inalámbricas de área amplia de bajo consumo energético son una tecnología clave para el desarrollo del Internet de las Cosas (IoT por sus siglas en inglés). Como todo sistema de comunicaciones inalámbricas, requiere que durante el diseño se inspeccione el lugar donde se desplegará la red para determinar las ubicaciones donde la señal es débil. Sigfox es una red con acceso inalámbrico que brinda el servicio de conectividad para Internet de las Cosas. Cuando los nodos sensores están ubicados dentro de edificios, el nivel de la señal recibida puede variar, debido a obstrucciones internas e interferencias, por lo que es necesario disponer de sistemas que tomen en cuenta las características técnicas de la red Sigfox, para medir los niveles de intensidad de la señal e identificar las ubicaciones donde no existe señal. El sistema obtiene información de los niveles de señal con el fin de identificar las ubicaciones en las cuales los nodos no tienen conectividad con la red y encontrar soluciones a este problema antes de implementar la red. La implementación del sistema utiliza nodos Sipy programados con Pymark y la nube de Sigfox, mientras que el desarrollo de la aplicación utiliza API y APIREST en el entorno de desarrollo de Visual Studio.
A STUDY ON ALPHA POWER LOMAX DISTRIBUTION
Authors: Bakoban Rana A. , Faraj Eman A. , Alsulami Najwa S.
Published: November 2022

In this paper, we refer to the new distribution an alpha power Lomax distribution. Various properties of the proposed distribution are obtained including mode, quantiles, entropies, and order statistics are obtained. Parameters of the proposed distribution are estimated using maximum likelihood, ordinary least squares and weighted least squares. Simulation study is conducted to compare between estimators.
Psychological Impact of Vision Loss
Authors: Boagey Heather , K. Jolly Jasleen , E. Ferrey Anne
Published: November 2022

A diagnosis of conditions leading to vision loss can be devastating and often impacts mental health. Understanding this allows us to consider what provisions might help those who are impacted. We undertook 18 semi-structured interviews with patients diagnosed with eye disease leading to vision loss to explore its psychological impact. Participants also completed the Beck Depression Inventory (BDI), providing a snapshot of their depression and anxiety levels at the time of interview. NVivo-12 software (QSR International Ltd, Burlington, Massachusetts, USA) was used to inductively analyse and code data to identify themes related to the psychological impact. Participants had a mean BDI score of 9.6, and thematic analysis generated five key themes and associated subthemes. Coming to terms with the diagnosis included discussion of subthemes of “denial” and moving towards “acceptance”. Effects on mental health included depression/low mood, anxiety, and stress-related worsening of vision. Loss included various losses following initial loss of vision. Effects on identity included facing a curtailed life, worry that visual impairment might define a person’s identity, and feelings of frustration with their own loss of function and with others’ reactions to their disability. The future included thoughts about long-term consequences, both negative and positive (e.g., maximizing experiences given the vision one has left). Although such a diagnosis will nearly always have a psychological impact and require work to move toward acceptance, support could mitigate impact on mental health, such as practical support (e.g., advice on low vision aids), and psychological support.
Pengembangan E-Modul Pada Materi Penjumlahan dan Pengurangan Pecahan Kelas V SD Negeri 27 Ampenan
Authors: Qolbuani Lulu' , Tahir Muhammad , Rosyidah Awal Nur Kholifatur
Published: November 2022

Pelaksanaan proses pembelajaran materi penjumlahan dan pengurangan pecahan bahan ajar kontekstual jarang digunakan karena materi didalamnya bersifat terbatas. Kompetensi siswa pada materi penjumlahan dan pengurangan pecahan masih kurang. Penelitian ini bertujuan untuk mendeskripsikan langkah-langkah pengembangan berdasarkan model ADDIE (Analysis, Design, Development, Implementation, Evaluation) dan mengetahui kelayakan e-modul materi penjumlahan dan pengurangan pecahan kelas V ditinjau dari aspek kevalidan dan kepraktisan. Subjeknya yaitu siswa dan guru kelas V SD Negeri 27 Ampenan. Teknik pengumpulan data yang digunakan yakni wawancara, angket, dan dokumentasi. Teknik analisis data yang digunakan yakni deskriptif dan kuantitatif. Hasil penilaian validator ahli materi menunjukkan bahwa materi dalam e-modul termasuk kualifikasi “baik” dan keterangan “layak/valid” dengan persentase skor 73,3%. Sementara hasil validasi dari ahli media menunjukkan bahwa e-modul termasuk kualifikasi “sangat baik” atau “sangat layak/sangat valid” dengan persentase skor 85%. Hasil penilaian pada uji coba kelompok kecil (6 siswa) dan uji coba kelompok besar (12 siswa) berturut-turut sebesar 77,3% dan 80,6% yang menunjukkan e-modul termasuk kategori “praktis”. Hasil penilaian guru menunjukkan e-modul termasuk kategori “sangat praktis” dengan persentase skor 90%. Berdasarkan hasil penelitian, e-modul pada materi penjumlahan dan pengurangan pecahan dapat dikatakan layak untuk digunakan ditinjau dari aspek kevalidan dan kepraktisan.
Nilai Pendidikan dalam Naskah Terjemahan Bo Sangaji Kai dan Pengamalannya oleh Masyarakat Bima
Authors: Yearham Nur Sakinah , Aswandikari Aswandikari , Qodri M. Syahrul
Published: November 2022

Penelitian deskriptif kualitatif ini bertujuan untuk mendeskripsikan, 1) nilai-nilai pendidikan yang terkandung dalam naskah terjemahan Bo Sangaji Kai, dan 2) pengamalan masyarakat Bima terhadap nilai pendidikan dalam naskah terjemahan Bo Sangaji Kai oleh masyarakat Bima. Subjek penelitian ini adalah kutipan-kutipan yang terdapat dalam naskah terjemahan Bo Sangaji Kai yaitu buku yang berjudul Bo Sangaji Kai Catatan Kerajaan Bima. Objek penelitian ini adalah nilai-nilai pendidikan yang terkandung dalam naskah terjemahan Bo Sangaji Kai. Metode yang digunakan untuk pengumpulan data adalah studi pustaka dan wawancara. Hasil penelitian ini menunjukkan bahwa; 1) di dalam naskah Bo Sangaji Kai terdapat nilai-nilai pendidikan yang mencakup pendidikan religius dan pendidikan sosial; 2) masyarakat Bima pada masa kesultanan umumnya mengamalkan aturan-aturan yang terkandung dalam Bo Sangaji Kai. Namun setelah masa kesultanan berakhir, masyarakat Bima tidak lagi menjadikan Bo Sangaji Kai sebagai aturan yang mengatur kehidupan, dengan demikian Bo Sangaji Kai tidak lagi diamalkan atau diterapkan dalam kehidupan sehari-hari.
A TRANSFORMAÇÃO DO EMPREENDEDORISMO DIANTE A CRISE GLOBAL CAUSADA PELO CORONAVÍRUS (COVID 19)
Authors: Santos Isabela Mendes , Silva Raiane dos Santos , Santos Geovanna Vitória Pereira , Pereira Magno Lucas Souza , Santos Vívia Pereira de Moraes
Published: November 2022

O empreendedorismo por sua vez, remete-se nas oportunidades de investir em novos negócios,
nessa abordagem, faz-se necessário compreender melhor o que a covid-19 nos proporcionou
além de tantas dificuldades e desafios, a crise que causou uma pandemia mundial desencadeou
múltiplas visões sobre o empreendedorismo, sobre viver o novo normal para que as empresas
não saíssem do mercado. Este artigo tem como objetivo geral analisar o impacto da pandemia
no empreendedorismo, e de forma específica i) apontar os desafios que o país passou no período
pandêmico, ii) avaliar as ações e estratégias utilizadas pelos empreendedores, e iii) aferir o
crescimento e as novas tendências do empreendedorismo no Brasil. Visto isso, torna-se cada
vez mais necessário que as organizações estejam acompanhando as evoluções e o que tem de
novo no mercado, diante de ações e estratégias, para que assim estejam cada vez mais
preparadas para futuras crises, principalmente no âmbito de restrições de recursos. Desse modo,
o artigo contribui significativamente para os estudos sobre empreendedorismo e inovação em
um ambiente instável como aquele causado pela pandemia do coronavírus.
APLICAÇÃO DE UM MODELO DE NEGÓCIO NO COMÉRCIO VAREJISTA ALIMENTÍCIO NA CIDADE DE PENEDO
Authors: Santos Matheus Silva , Fé Vitória Salgueiro da , Gomes Izabel Pinheiro de Oliveira , Silva Letícia dos Santos , Santos Vívia Pereira de Moraes
Published: November 2022

O atual cenário de mercado para as empresas é de extrema competitividade entre elas. No ramo
das empresas varejistas alimentícias é notório essa situação. Por isso, é necessário que o
empreendedor tente buscar estratégias assertivas para o empreendimento e entender
completamente todos os setores da organização, tanto em seu ambiente interno quanto externo.
O marketing bem trabalhado pode ser um benefício positivo para organização a fim de
conseguir se sobressair diante de outras empresas e alavancar as vendas. Em vista disso,
apontam-se situações para que empreendedor consiga se encaixar diante das constantes
mudanças que ocorrem no mercado atual. Para isso, é necessário a realização de um modelo de
negócio Canvas. O empreendedor terá todas as informações necessárias para conseguir aplicar
suas estratégias no quadro do Canvas, visto que será proposto esta sugestão aos empreendedores
do ramo varejista alimentício na cidade de Penedo-AL. A metodologia utilizada é de uma
abordagem descritiva na tipologia qualitativa. Portanto, o presente artigo poderá auxiliar esta
classe de comerciantes a fomentar o desenvolvimento dos seus empreendimentos.
NAÇÃO E NACIONALIZAÇÃO NA FRONTEIRA
Authors: Sausen João Vitor
Published: November 2022

Adaptada a partir de sua Dissertação de Mestrado, defendida em 2022 na Universidade Federal de Santa Maria (UFSM), orientada pela Profª. Drª. Maria Medianeira Padoin e coorientada pela Profª. Drª. Sonia Rosa Tedeschi (UNL, Argentina), a obra de João Vitor Sausen aborda, de forma comparada, as políticas de integração das populações de teuto-brasileiros estabelecidas em Puerto Rico (Argentina) e Porto Novo (Brasil) entre 1919 e 1945. Esta perspectiva está voltada a um período de reflexões nacionalistas em ambos os países, que lançam um olhar sobre aqueles grupos “desnacionalizados” ou não integrados presentes em seus territórios. À luz do expansionismo da Alemanha Nazista, bem da Segunda Guerra Mundial na Bacia Platina, a questão adquire contornos ainda mais tensos. Desta forma, a perspectiva comparada e a análise de um conjunto documental variado, elucidam uma profunda trama de inserção dos Estados-Nação nas localidades abordadas, bem como as contínuas conexões presentes neste espaço fronteiriço, que geram circulações, desconfianças mútuas e processos de migrações forçadas.
O DISCURSO SOBRE A MORTE NO ARQUIVO
Authors: Pedrazzi Fernanda Kieling
Published: November 2022

Este livro procura compreender o discurso sobre a morte encontrado nos arquivos institucionais visitados para reunir fontes de pesquisa. A questão teórica gira em torno do discurso sobre . São consideradas como base da análise as teorias e noções da área de Linguística, Letras e Artes , área básica Linguística , trabalhando com a Análise de Discurso de Linha Francesa. A área de Ciências Sociais Aplicadas , área básica Ciência da Informação , também é vislumbrada ao trabalhar com as ideias de arquivologia e informação. A partir do conhecimento desses campos disciplinares distintos: Análise de Discurso e Arquivologia, é feito um gesto de leitura e análise na materialidade selecionada. Para tanto, foi realizado um enquadramento privilegiando Santa Maria, RS, e tendo 1896 como ano referência das mortes. São feitos levantamentos de: 1) atestados de óbito produzidos/recebidos pela Intendência Municipal e mantidos no acervo do Fundo Intendência do Arquivo Histórico Municipal de Santa Maria; 2) registros de óbito realizados na Catedral e guardados no Arquivo da Arquidiocese; e 3) registros feitos nos livros do Cartório. Foi feita uma comparação entre os três conjuntos, chegando ao nome de 197 diferentes pessoas. Buscou-se reconhecer aqueles falecidos comuns aos três conjuntos, formando, assim, o corpus empírico da pesquisa (com 12 mortos e suas comunicações). A pesquisa foi complementada por notícias de jornal local e por um inventário post-mortem do Arquivo Público do Estado do Rio Grande do Sul. Foram realizados recortes do campo discursivo de referência baseado em cinco domínios de discurso sobre a morte: o discurso médico, o religioso, o jurídico, o jornalístico e o de privacidade, proposto como uma nova categoria. Neles foram recortadas as sequências discursivas onde se observou o discurso sobre a morte. A movência dos sentidos das palavras no funcionamento da linguagem e a relação entre historicidade e discurso são presenças constantes.
Math is beautifully intimidating: Analyzing the conflict between teacher affective disposition and observed positioning-by-others
Authors: Lynch-Arroyo Ruby L. , Tchoshanov Mourat , Medina-Jerez William
Published: November 2022

Teacher productive disposition is considered as one of the key strands of mathematical proficiency. Teacher disposition and positioning (disposition in action) toward mathematics influence student learning. However, teachers’ productive disposition does not always translate into productive positioning in the mathematics classroom, and vice versa. In this study, we selected teacher dis/position as the unit of analysis to explore the phenomenon of two middle school mathematics teachers’ self-reported affective disposition and observed positioning-by-others. Grounded in positioning theory the relationship between teacher disposition and positioning-by-others was examined utilizing a cross-case analysis. Results of the study indicate that dispositional characteristics such as attitude, self-concept, and nature of mathematics were significantly different between the cases. The study findings also suggest that interconnectedness between teacher core disposition and positional situatedness could potentially contribute to understanding and addressing the complexity of teaching and learning in the mathematics classroom.
Crise e transformação do conceito de autoridade na Igreja e na sociedade de hoje
Authors: Gründel Johannes
Published: November 2022

Não há quem possa negar, hoje em dia — ao menos na Europa e na América do Norte — que o conceito de autoridade está passando por uma grave crise, e isto em princípio: tanto na Igreja como na Sociedade em geral. Está havendo uma transformação gradativa do conceito de autoridade, de obediência, de crítica, e uma nova maneira de interpretá-lo. Principalmente no campus universitário se manifesta semelhante processo evolutivo, em formas bem crassas, às vezes, e pondo à mostra inequívocas tendências revolucionárias...
Tamaño muestral para la estimación de una proporción.: Si dudas, mejor al medio.
Authors: Manuel Molina
Published: November 2022

El tamaño muestral necesario para estimar una proporción poblacional depende del nivel de confianza y precisión deseados, además del valor de la proporción en la población.
Anestesia para esofagectomía en un paciente con vía aérea difícil (VAD).
Authors: Sofía Adonina Nicolás Aller  , Natalia Riego del Castillo  , Fernando Díez Burón  , Santiago Fernández Manovel
Published: November 2022

La cirugía oncológica esofágica es siempre un reto para el anestesiólogo debido a la agresividad de las técnicas quirúrgicas empleadas según la localización del tumor y la experiencia del equipo quirúrgico. El abordaje transtorácico o técnica de Ivor-Lewis es una cirugía en dos campos: laparotomía para la gastroplastia y toracotomía derecha con ventilación unipulmonar (VUP) para la disección, resección tumoral y anastomosis. El paciente presentaba distorsión de la vía aérea debido a cirugía orofaríngea y radioterapia (RT) previas, además de neoadyuvancia para el tumor esofágico. Por ello se decidió una intubación orotraqueal despierto, con fibrobroncoscopio (FOB), utilizando un tubo endotraqueal estándar (TET). A través de él, se introdujo un bloqueador bronquial independiente (BB) hacia el bronquio pulmonar derecho. La intervención se realizó sin incidencias y se logró la exclusión pulmonar adecuadamente.
Renal and electrolyte profiles of Wistar albino rats fed with Irvingia wombolu kernel powder and its oil extract
Authors: Abubakar Alhassan  , Sunday  Salifu Arogba
Published: November 2022

Irvingia gabonensis Kernel powder and the oil extracts with and without testa (±testa)were mixed with commercial animal feed (50:50)and fed to groups of animals. Animals in groups A and B were fed with the powder at an equivalent concentration of 67mg/kg body weight while those in groups C and D were fed with the equivalent4ml of the oil extract in the mixture. Animals in group E, the control, were fed on the commercial feed only. All the animals were fed in an aluminum cage for 21 days and sacrificed the following day. Blood from the jugular vein was collected in universal bottles and used for determination of creatinine, urea, sodium, potassium and bicarbonate. It was observed that all the treated groups and the control showed no significant difference (P≥0.05) in their Nak concentrations. There were significant differences(p≤ 0.05) in the K+ concentrations between groups A,B, E and groups C, D respectively .Significant statistical differences(P≤0.05) were also observed in the creatinine concentrations of all the treated groups with the exception of group C. There were higher urea concentrations in groups C and D than A, B and E(P≤0.05).Bicarbonate showed the least concentration in group E with relatively higher concentrations in groups C and D(P≤0.05)
Occurrence of ABO and Rh D blood groups in Sudanese population attending blood bank, Gezira state, Wad Madani, Sudan, 2021
Authors: Asad Adam Abbas  , Soad Fadal Allah Ali
Published: November 2022

Objective: To detect the frequency of ABO and Rh D blood groups among Sudanese blood donors attending the Gezira center for Trauma and Orthopedic Blood Bank in Wad Madani. Material and Methods: One thousand male blood donors were enrolled in the study, ABO typing and Rh D were performed using the classical slide method. Results: The study revealed that frequency percentage of ABO blood phenotypes in the total samples were as follows: O (51%), A (30%), B (14%) and AB (5%), The Majority (97.4%) of the subjects were Rh (D) positive and only 2.6% were Rh negative. Conclusion: The frequency of ABO blood groups among the Sudanese was similar some extend with world ABO distribution with predominance of Rh D positive.
Impact of militancy on education and economic security in Niger delta region of Nigeria
Authors: JEREMIAH Samuel Okon  , ZAMANI Andrew  , NWOTA Ogbonnaya  , OMOREGIE Bright
Published: November 2022

The extensive militarization of the Niger Delta region further elicited a long drawn militancy postures from the restive youth, and the impact of the opposing postures of both State armed actors and non-state armed actors, could be seen aggravating both education security and economic security of the region. It was against this background that this engages relative deprivation theory to investigate the impact of militancy on human security in Niger Delta. The study looked at economic security and education as constructs of human security. This study adopts exploratory research design; using content analysis of publicly available archive documents. The study relies on secondary data. The research is conducted by examining literature concerning militancy and human security in Nigeria. The literature was obtained through searches in publicly available material. Literature from non-serial publications, official reports, and conferences has been included particularly if they have been cited by other references in term of economic security and education security. The study revealed that militancy has negative effects on economic security and education security in Nigeria. Based on these findings, the study concludes that provision of employment opportunities and protection of schools with accessibility to education will go a long way to ensure human security particularly in the Niger Delta region. The study recommends that Federal, State and Local Government evolve adequate protections for education, as that is a conduit of learning tolerance, balance socialisation and civility as against violent narratives from militancy while efforts should be focused on provision of jobs and economic activities to counter the negative narratives of apparent poor governance, used as recruitment bait for the youths into mainstream of militancy in the region.
Role of peptidomimetics for new drug discovery
Authors: Sai priya K  , Raju Darla  , Poojitha Gone
Published: November 2022

The art of transforming peptides into drug leads is still a powerful and fertile field in medicinal chemistry and drug discovery. Peptidomimetics can respond to peptide limitations by displaying higher metabolic stability, good bioavailability and increasing receptor affinity and selectivity. Various synthetic approaches and strategies have been developed over the years in order to modulate the conformational flexibility and the peptide nature of peptide mimetic compounds. This review aims to outline useful tools towards peptide mimetic design, spanning from local modifications, global restrictions and the use of secondary structure mimetics. Key learning points: Advantages of peptidomimetics over peptides, definition and classification of peptide mimetics, synthetic strategies and molecules for local modifications, secondary structure mimetics, global restrictions and Applications of peptide mimetics in drug discovery. Selected best examples of each approach are presented to document the relevance of peptidomimetics in new drug discovery.
Influence of rigid and flexible matrices on ultimate strength and fracture mechanisms of polymer composite materials upon impact and static loading conditions
Authors:   Baikov Institute of Metallurgy and Materials Science of RAS, Krylov I. K. , Korneeva N. V. ,   Semenov Federal Research Center of Chemical Physics Russian Academy of Sciences, Kudinov V. V. ,   Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences
Published: November 2022

An universal method “Break upon Impact and Static” (RUS) has been developed for the experimental determination of the ultimate strength properties of polymer composite materials based on multifilament nanocrystalline ultra-high molecular weight polyethylene (UHMWPE) fibers, which differs in the method of fixing the sample in a testing machine.The method is carried out using a uniform BIS-sample with an intermediate matrix at the ends and equipment for its attachment to the platforms of testing machines. The sample is a round composite rod composed of the fibers and matrices under investigation, which is held in the tooling by an additional matrix that fixtures it under various loading rates. The RUS method was used to study the properties and mechanisms of destruction upon impact and in a static situation of anisotropic polymer and hybrid composite materials (PCM and HCM) based on flexible and rigid matrices reinforced with hybrid fibers of carbon, aramid, and UHMWPE-fibers activated by non-equilibrium low-temperature plasma. The breaking loads under low-velocity impact and static bending conditions, relative deformation, specific absorbed-in-fracture energy, work of adhesion, shear strength, and other properties are determined. It was found out that the plasticity of the matrix and the hybrid fiber composition affect the properties and fracture mode of PCM and HCM. For the destruction of HCM with a flexible matrix upon impact, a load twice as large as for composites with a rigid matrix is required. HCMs have the highest strength, in which at all stages of loading up to failure, joint deformation of the matrix and the reinforcing fiber occurs. The mechanism of deformation and destruction of anisotropic HCM upon impact is stepwise, while the nature of the deformation curve is zigzag. In statics, the deformation proceeds smoothly. By changing the ratio of carbon and UHMWPE-fibers during hybridization, it is possible to control the properties of HCM and improve its specific properties. The combination of carbon and UHMWPE-fibers in a hybrid fiber for reinforcing a flexible matrix makes it possible to create a material with a delayed fracture. It has been established that for HCM based on a flexible matrix reinforced with a hybrid fiber combining 20 % carbon and 80 % UHMWPE fiber, the fracture load increases by factor 2, the specific fracture work by 42 %, relative deformation by 68 %.
УПРАВЛЕНИЕ ЭКОНОМИЧЕСКОЙ ДИНАМИКОЙ РЕГИОНОВ: ТРАЕКТОРИИ ВЗАИМОДЕЙСТВИЯ
Authors:   Институт проблем управления им. В.А. Трапезникова РАН, ПЕТУХОВ Н. А. , ИВАНОВ Е. Ю. , РОСЛЯКОВА Н. А. , ШВЕЦ И. Ю.
Published: November 2022

Монография посвящена обсуждению вопросов управления экономической динамикой регионов, в том числе межрегионального взаимодействия – интеграции, дифференциации, взаимного влияния, формирования и реализации конкурентных преимуществ. Особое внимание уделяется развитию регионов Российской Федерации, ключевым факторам и показателям управления этим развитием. Для преподавателей, научных сотрудников, специалистов в области региональной экономики, экономической политики, управления развитием социально-экономических систем, аспирантов и студентов старших курсов экономических и инженерно-экономических специальностей.
DEFLAGRATION-TO-DETONATION TRANSITION IN STOICHIOMETRIC BINARY HYDROCARBON (METHANE, PROPANE, ETHYLENE) HYDROGENBLENDS IN AIR
Authors:   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, SHAMSHIN I. O. , KAZACHENKO M. V. , FROLOV S. M. , BASEVICH V. YA. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences
Published: November 2022

Systematic experimental studies of de§agration-to-detonation transition (DDT) in binary hydrocarbon (methane, propane, ethylene) hydrogen air mixtures of stoichiometric composition with hydrogen volume fraction xH2 varied from 0 to 1 are conducted at normal pressure and temperature conditions in a pulse-detonation tube of three geometrical con¦gurations: C1, C2, and C3 (Fig. 1). Contrary to expectations based on the well-known high reactivity of hydrogen, the measured dependences of the DDT run-up distance LDDT and time τDDT on xH2 are shown to be highly nonlinear [1 3]. Thus, in methane hydrogen air mixtures, with an increase in xH2 , the DDT run-up distance changes nonmonotonically: in the range 0.25 < xH2 < 0.65, the dependences LDDT(xH2 ) can have local maxima, i. e., the detonability of such fuel air mixtures deteriorates with the addition of hydrogen (Fig. 2a). In propane hydrogen airmixtures, the measured dependences of the DDT run-up distance appear to be nonlinear and nonmonotonic (in some cases): mixture detonability increases sharply only at relatively large hydrogen content (at xH2 > 0.7) (Fig. 2b). Finally, in ethylene hydrogen air mixtures, hydrogen addition to ethylene at 0 ≤ xH2 ≤ 0.7 results in no variation of mixture detonability in terms of DDT run-up distance (Fig. 2c). However, hydrogen addition to ethylene at xH2 > 0.7 results in a drastic increase of mixture detonability. Since various modi¦cations of tube design do not affect the character of the dependences, these e¨ects are attributed to the physicochemical properties of the mixtures. In general, based on the similarity of the experimental results for methane hydrogen air, propane hydrogen air, and ethylene hydrogen air mixtures obtained using the same experimental facilities and conditions, one can conclude that such unexpected dependences are caused by chemical and physical properties of hydrogen, namely, its temperature and pressure dependent reactivity in terms of the laminar §ame velocity, selfignition delay, etc., as well as its low molecular mass.
ОПРЕДЕЛЕНИЕ ВРЕМЕН ИНДУКЦИИ И РЕАКЦИИ СМЕСЕЙ ВОДОРОДА С ВОЗДУХОМ ПРИ ВЫСОКИХ ТЕМПЕРАТУРАХ
Authors:   Институт тепло- и массообмена им. А. В. Лыкова Национальной академии наук Беларуси, БАРАНЫШИН Е. А. , ПЕНЯЗЬКОВ О. Г. ,   Институт тепло- и массообмена им. А. В. Лыкова Национальной академии наук Беларуси, СЕВРУК К. Л. ,   Институт тепло- и массообмена им. А. В. Лыкова Национальной академии наук Беларуси
Published: November 2022

Моделирование процессов горения в проточной части воздушно-реактивных двигателей при больших числах Маха полета требует знания кинетических особенностей поведения топлив при очень высоких температурах торможения потока. В этих условиях время индукции топливно-воздушной смеси становится сравнимым с временем ее реакции. Точное экспериментальное определение этих кинетических параметров позволяет проводить адекватные оценки габаритных параметров проточной части двигательной установки при выборе той или иной топливной смеси.
О ВЫБОРЕ ОПТИМАЛЬНЫХ ТИПОВ КАМЕР СГОРАНИЯ ПРИ ИНИЦИИРОВАНИИ ГАЗОВОЙ ДЕТОНАЦИИ
Authors:   Институт гидродинамики им. М. А. Лаврентьева Сибирского отделения Российской академии наук, ВОРОНИН Д. В.
Published: November 2022

Проведено численное моделирование непрерывной газовой детонации в камере сгорания на основе уравнений Навье–Стокса с учетом турбулентности и диффузии веществ. Выполнен сравнительный анализ эффективности детонационного сгорания топлива в зависимости от геометрических параметров камер. Рассмотрены три возможных типа камеры (см. рисунок). Горючее и окислитель подавались в камеры раздельно через форсунки $S_1$ под определенным углом к поверхности камеры. Детонационный процесс во многом определялся интенсивностью турбулентного перемешивания реагентов (водород и кислород). Поверхность $S_2$ — область выхода продуктов детонации в атмосферу. Как показывают расчеты, для камеры первого типа характерно образование локальных зон с повышенными значениями термодинамических параметров, что может приводить к самопроизвольному {воспламенению} топлива и неоптимальному режиму работы двигателя. Здесь подача газа осуществляется сверху, а выход — направо. У стенки канала в пограничных слоях образуется область с повышенными значениями температуры (около 2000 K), что превышает температуру самовоспламенения смеси (1200 K). Для камеры второго типа характерно возникновение застойных зон у поверхности $S_1$ и выход значительной части непрореагировавшего топлива в атмосферу. Давление газа в камере у поверхностей входа $S_{11}$ и $S_{12}$ достигает значений 12 атм, что превышает давление газа в ресиверах (10 атм). Это приводит к запиранию потока и временному прекращению поступления водорода и кислорода в проточную камеру. Если поверхность $S_2$ расположена достаточно близко к поверхностям входа (менее 20 мм) и волна разрежения быстро уменьшит значения давления и температуры реагирующего газа, то наступает срыв детонации, что нарушает оптимальное функционирование камеры. Наиболее оптимальной выглядит камера 3-го типа, имеющая наиболее простую форму и позволяющая регулировать процесс перемешивания, меняя угол наклона струй топлива и окислителя по отношению к поверхности.
НОВЫЕ РЕЗУЛЬТАТЫ ИССЛЕДОВАНИЙ РАСПРОСТРАНЕНИЯ ДЕТОНАЦИИ В ВЯЗКОМ ТУРБУЛЕНТНОМ ТЕЧЕНИИ В КАНАЛЕ
Authors:   Центральный аэрогидродинамический институт имени профессора Н. Е. Жуковского (ЦАГИ), САБЕЛЬНИКОВ В. А.
Published: November 2022

Большинство исследований детонации посвящено распространению детонационных волн в каналах с покоящейся горючей {смесью} или в открытом пространстве. В экспериментах Белле и Деэ [1] было рассмотрено распространение детонационной волны против сверхзвукового потока в канале квадратного сечения с пограничными слоями. При помощи высокоскоростной шлиренвидеосъемки было обнаружено, что рост давления в детонационной волне вызывает отрыв пограничных слоев с образованием маховской ударно-волновой структуры. Авторы наблюдали распространение самоподдерживающейся детонации. Удивительный результат эксперимента — вывод о том, что скорость последней превосходила скорость классической детонации Чепмена–Жуге.
О НЕКОТОРЫХ ДИНАМИЧЕСКИХ ЯВЛЕНИЯХ ПРИ РАСПРОСТРАНЕНИИ ГАЗОВОЙ ДЕТОНАЦИИ В СРЕДЕ С ПЕРИОДИЧЕСКОЙ НЕОДНОРОДНОСТЬЮ
Authors:   Сколковский институт науки и технологий, ГОЛДИН А. Ю. , КАСИМОВ А. Р. ,   Сколковский институт науки и технологий,   Институт компьютерных наук и математического моделирования, Сеченовский университет
Published: November 2022

Мы рассматриваем динамику одномерной волны детонации в газовой смеси с периодически меняющимися в пространстве свойствами. Это могут быть неоднородности температуры или концентрации топлива или неоднородности, связанные со свойствами канала, в котором распространяется волна. Хорошо известно, что одномерная детонация может распространяться со скоростью, зависящей от времени периодически или хаотически. Возникает вопрос о влиянии периодической неоднородности в горючей смеси на такую нестационарную динамику детонации. Этот вопрос исследовался ранее как в рамках модельного уравнения Бюргерса [1, 2] так и на основе уравнений Эйлера [3, 4]. В этих работах были обнаружены явления резонансного усиления колебаний скорости детонации и захвата частот. Последнее означает, что нерегулярные колебания скорости детонации при распространении в однородной среде могут быть стабилизированы в том смысле, что они становятся более регулярными, если волна бежит по периодически неоднородной среде. Стабилизация зависит от амплитуды и длины волны неоднородности. В данной работе продолжено исследование этих явлений в рамках уравнений Эйлера для идеального газа, реагирующего согласно модели Аррениуса. Обнаружено, что процесс захвата частот приводит к возникновению языков Арнольда и захвату мод разного порядка [5]. Рассчитанные для этого процесса числа вращений в зависимости от волнового числа периодичности в исходной смеси имеют вид дьявольской лестницы подобно тому, что наблюдается на практике и в некоторых более простых динамических системах [6, 7]. С той же целью выяснения влияния внешних периодических воздействий на нестационарную детонацию мы также исследовали одномерную детонацию в канале с неоднородной шероховатостью и двумерную детонацию в канале с учетом потерь импульса и тепла. В одномерной задаче с потерями динамика взаимодействия во многом подобна той, что имеет место при распространении детонации в неоднородной смеси. В двумерном случае возникают некоторые новые явления, связанные с особенностями ячеистой структуры.
TESTING OF SPECIAL EQUIPMENT FOR VIDEO RECORDING OF DETONATION WAVES
Authors:   Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences, SAMSONOV A. N. , TSARKOVA A. V. ,   Novosibirsk State University, BYKOVSKII F. A. ,   Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences
Published: November 2022

A device developed for optical registration of detonation processes is described. Some ways of improving the quality of data that were registered during the experiment and some ways of reducing resources and time of data processing are investigated and described. Software and hardware methods are considered. The methods which are suitable for the device specially designed for recording detonation waves are described. The developed device is shown to be capable of registering detonation processes. Moreover, it has a longer readout line length than most of standard high-speed cameras. Device reliability is based on its low power assumption.
REALIZATION OF CONTINIOUSLY ROTATING DETONATION FOR SYNGAS AIR MIXTURES
Authors:   M. A. Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Science, TROTSYUK A. V.
Published: November 2022

Numerical simulation of continuously rotating detonations of stoichiometric two-fuel mixture with air has been carried out for the cylindrical annular detonation chamber (DC) of the rocket-type engine. The syngas (1−α)CO+αH2, a binary mixture of hydrogen H2 and carbon monoxide CO, is considered as a fuel. The global §ow structure in the DC and the detailed structure of the transverse detonation wave front in the continuous rotating regime have been studied. Integral characteristics of the detonation process ¡ the distribution of average values of static and total pressure along the length of the DC and the value of speci¦c impulse at the DC exit ¡ have been obtained. The regions of existence of stable continuous rotating detonation regime in coordinates ¤stagnation pressure pm stagnation temperature Tm¥ in injection manifold (receiver) have been determined. The minimal values of the DC length and radius for stable rotating detonation for some regions at the pm Tm plane have been found.
CRITICAL CONDITIONS OF DROPLET PUFFING AND MICROEXPLOSION MODES
Authors:   National Research Tomsk Polytechnic University, ANTONOV D. V. , STRIZHAK P. A. ,   National Research Tomsk Polytechnic University
Published: November 2022

Microexplosion e¨ects in composite droplets make it possible to improve integral characteristics of secondary atomization processes in the combustion chamber, to increase completeness of fuel combustion, to reduce ignition time delay, and to diminish anthropogenic emissions [1]. The purpose of this work is experimental and theoretical research of critical conditions of pu©ng and microexplosion modes. The experimental research of microexplosion e¨ects in composite droplets was carried out by varying the temperature of the gaseous medium (473 1523 K) and atmospheric pressure [2]. The in§uence of the gaseous medium temperature and solid particles and gas bubbles concentrations on the time delay of droplets fragmentation were investigated. The droplet heating, evaporation, and breakup characteristics were recorded using a Phantom Miro high-speed slow-motion video camera with a frame rate of 2000 fps at 512 × 768-pixel resolution. The experimental video fragments were processed in the Phantom Camera Control software to analyze the initial droplet size before they enter the heating zone and to estimate the distance between them. The systematic errors in the measurement of these parameters did not exceed 0.025 and 0.05 mm, respectively. The problem of modeling pu©ng/microexplosion of composite water/fuel droplets was examined with using model for pu©ng/ microexplosions [3]. The most recent model [3] is based on the analytical solution to the one-dimensional heat transfer equation in a composite droplet assuming that a spherical water subdroplet is placed exactly in the center of a spherical fuel droplet. The analytical solution to this equation with the Robin boundary condition at the droplet surface was obtained, implemented into the numerical code, and used at each time step of the calculations. The e¨ects of thermal swelling and evaporation, using the Abramzon and Sirignano model, are considered. The developed mathematical apparatus can be helpful in developing high-temperature gas vapor drop technologies associated with ignition and combustion of liquid and slurry fuels.
SIMULATION OF INTERACTION OF HOMOGENEOUS HYDROGEN AIR DETONATION WITH POROUS FILTERS
Authors:   S. A. Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences, TROPIN D. A. , VYSHEGORODCEV K. A. ,   S. A. Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences
Published: November 2022

Explosions of combustible industrial gases and gas suspensions are one of the main causes of technological disasters. An example of the catastrophe is the explosion in the city of Kaohsiung, Taiwan, related with propylene leak in 2014. The explosion occurred during the transportation of propylene from the port to a chemical plant through a pipeline laid in underground utilities. One of the ways to prevent the catastrophic consequences of such incidents is to use inert components, for example, solid inert particles, porous ¦lters, or inert gas plugs to suppress detonation. In the present study, physical and mathematical modeling of the interaction of two-dimensional cellular detonation wave in hydrogen air mixture with inert porous ¦lters is performed. The model is based on the system of Euler equations describing the interaction of gas and ¦lters including the laws of mass, momentum, and energy conservation for each of the phases and components closed by equations of state, momentum exchange (drag forces), and heat transfer between gas and porous ¦lter. Hydrogen combustion is described by a reduced chemical kinetics. It was assumed that the porous ¦lter is a continuous medium in the form of a grid of stationary cylinders.
SIMULATION OF INTERACTION OF HETEROGENEOUS DETONATION WITH POROUS INSERT
Authors:   S. A. Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences, LAVRUK S. A. , TROPIN D. A.
Published: November 2022

Investigation of the process of a detonation wave (DW) interaction with various obstacles is a fundamental problem. This problem is relevant from the point of view of reducing the destructive e¨ects of heterogeneous explosions in technological disasters and in the studies of the process of de§agration-to-detonation transition and in detonation engines development. In this study, the authors tried to model the heterogeneous detonation of stoichiometric mixture of aluminum particles in oxygen with semi-in¦nite porous insert as a grid of stationary cylinders. The model is based on the system of Euler Euler equations for describing the interaction of continua including the laws of mass, momentum, and energy conservation for each of the phases and components closed by equations of state, momentum exchange (drag forces), and heat transfer between gas, particles, and porous body. Aluminum combustion is described as a reduced reaction initiated after the critical temperature is reached assuming incomplete particle burning. It was assumed that the porous zone is a continuous medium in the form of a grid of stationary cylinders. During the numerical simulation, some §ow regimes were obtained similar to those that were previously obtained in the study of the interaction of detonation waves with inert particles as well as with water sprays. There are regimes with a reduced DW velocity and regime with detonation failure with separation of shock wave and reaction front. Figure compares the results of one- (1D) and two-dimensional (2D) simulations of the propagation regimes of heterogeneous detonation of 1-micrometer aluminum particles in oxygen in a porous zone with a 200-micrometer cylinders. It can be seen that the results are quite similar to each other.
О МЕХАНИЗМЕ АЭРОАКУСТИЧЕСКОЕО ИНИЦИИРОВАНИЯ ПУЛВСИРУЮЩЕЕО КВАЗИДЕТОНАЦИОННОЕО ЕОРЕНИЯ В ЭЖЕКТОРНОМ ПУЛВСИРУЮЩЕМ ВОЗДУШНО-РЕАКТИВНОМ ДВИЕАТЕЛЕ
Authors:   ООО НПФ «Ротор», МИГАЛИН К. В. , СИДЕНКО А. К. ,   Тольяттинский государственный университет
Published: November 2022

Сегодня известны два метода поддержания пульсирующего горения в пульсирующем воздушно-реактивном двигателе (ПуВРД): (1) акустический, он реализуется в условиях акустического резонанса газохода; (2) релаксационный, базируется на основе использования различного рода механических устройств пульсирующей подачи топлива или воздуха. К настоящему времени известно только о нескольких разработках детонационных двигателей, реализующих второй способ поддержания пульсирующего горения. Одна из них, прошедшая стадию бросковых испытаний, описана в [1]. Эти двигатели реализуют продольную детонацию в газоходе и требуют его большой длины. Авторами найден третий метод поддержания пульсирующего горения в бесклапанном ПуВРД, при котором возможен переход к редкому виду детонационного или квазидетонационного горения — сферической детонации. Такой метод поддержания пульсирующего горения возможен в двигателях, имеющих специфическую внутреннюю аэродинамику течения, формируемую специальной конструкцией газохода. Приведены результаты аэроакустических исследований газоходов малоизвестного типа двигателей — эжекторных двухконтурных ПуВРД (ЭДПуВРД). Показано, что конфигурация газохода с двойным изломом приводит к сложной вихревой структуре внутреннего течения, которая подвержена влиянию акустических колебаний [2]. Подбором частоты акустического резонанса газохода производится настройка на частоту собственных колебаний внутренних вихревых течений, чем достигается появление прецессии вихревого течения. Циклический выброс из нее продуктов сгорания, являясь мощным источником воспламенения, в свою очередь провоцирует переход к детонационному горению. В случае работы в режиме дефлаграционного горения с применением бензина А-76 или керосина РТ двигатели рассматриваемого типоразмера демонстрируют устойчивую работу в диапазоне скоростей до М = 1,5 и выше, развивая тягу 170–220 кГс. Удельная тяга по топливу при этом достигает 1500 с при весе двигателя 22–24 кг. Основные преимуществами ЭДПуВРД — простота конструкции и невысокая стоимость, что на фоне масштабного вырождения турбинных датчиков расхода турбореактивных двигателей в классе двигателей малых тяг расширяет нишу его возможного применения.
GASIFICATION OF GASEOUS, LIQUID, AND SOLID WASTES WITH DETONATION-BORN ULTRASUPERHEATED STEAM
Authors:   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, FROLOV S. M. , SMETANYUK V. A. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, SADYKOV I. A. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, SILANTIEV A. S. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, SHAMSHIN I. O. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, AKSENOV V. S. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, AVDEEV K. A. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, FROLOV F. S. ,   N. N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences
Published: November 2022

The pulsed detonation gun technology for gasi¦cation of organic waste with ultrasuperheated steam [1, 2] has been demonstrated experimentally for the ¦rst time. The organic waste converter consisted of a pulsed detonation gun and water-cooled spherical §ow reactor (Fig. 1). Experiments on methane conversion as well as on the gasification of liquid (waste machine oil) and solid (sawdust) waste by the high-temperature gaseous detonation products of methane oxygen mixture were performed. The pulsed detonation gun was operated at a relatively low frequency of f = 1 Hz which provided a timeaveraged mean temperature of detonation products in a spherical §ow reactor at a level of 1200 K at a time-averaged absolute pressure in the reactor slightly higher than P = 1 atm. The novel technology was shown to provide complete (100%) conversion of methane into syngas containing H2 and CO with a ratio of H2/CO ≈ 1.25 2. Gasi¦cation of liquid and solid wastes led to the production of syngas containing reactive components H2, CO, and CH4 in the total amounts of 80 and 65 %(vol.) dry basis (d. b.), respectively. The corresponding H2/CO ratios in the product syngas were 0.8 and 0.5. Overall, experiments on methane conversion as well as liquid and solid waste gasi¦cation showed that under the same conditions at f = 1 Hz and P = 1 atm, the composition of syngas in terms of H2 and CO almost did not depend on the type of feedstock (Fig. 2).