Academic literature on the topic 'Semi-enclosed core'
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Journal articles on the topic "Semi-enclosed core"
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Δημητράκος, Α. Σ., Κ. Βουβαλίδης, Γ. Συρίδης, and Κ. Αλμπανάκης. "Παλαιοπεριβαλλοντική εξέλιξη της λιμνοθάλασσας του Κίτρους Πιερίας, ΒΔ Θερμαϊκός Κόλπος." Bulletin of the Geological Society of Greece 44 (February 1, 2017): 90. http://dx.doi.org/10.12681/bgsg.11439.
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This paper deals with the palaeoenvironmental evolution of the Kitros Pierias Lagoon, located at the west coastline of the Thermaikos Gulf, during the upper Holocene. In addition, the palaeoenvi-ronmental units distinguished in the study area were correlated with the Holocene sea level rise in Thermaikos Gulf. The study is based on the sedimentological and stratigraphical analysis of a core 9.5 m long. Sedimentological and palaeontological analysis was carried out in all selected core sam-ples. The determination of the lithophases and biophases allowed the estimation of the stratigraphy-cal units, the interpretation of the geomorphological evolution and the characterization of the palaeo-environmental conditions. According to the results, we can conclude that the area under investigation was a transitional lagoonal environment, semi-enclosed at its initial stage progressively transformed to an isolated sallow basin. The formation of the semi-enclosed lagoon has been commenced after the conclusion of the rapid phase of sea level rise i.e. 6,000 BP years. Finally, the gradual isolation of the lagoon is attributed to low rate of the sea level rise e.g. over the past 4,000 years..
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Pan, Rui, Robert Shanks, and Yong Liu. "The Effect of Humping Semi-Enclosed Cage Structure on Polymer Chains Characteristics of TSI-POSS/PU Hybrid Composites." Applied Mechanics and Materials 751 (April 2015): 30–34. http://dx.doi.org/10.4028/www.scientific.net/amm.751.30.
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Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with the humping semi-enclosed cage structure, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4’-methylenebis (phenyl isocyanate) (MDI) and glycerol propoxylate to prepare TSI-POSS/PU hybrid composites, respectively. The polymer chain characteristics of these composites were investigated by wide angle X-ray scattering (WAXS) and molecular dynamics simulation approach. The results indicate that with TSI-POSS concentration increasing up to 22 wt% in hybrid composites, due to the humping semi-enclosed cage structure, distinct crystallite clusters are formed which lead to the micro-phase separation in composites. Meanwhile, the mobility of TSI-POSS cores and backbones in PU composites has been evaluated by the mean square displacement, which confirms that as the concentration of TSI-POSS increasing, the mobility of polymer chains are restricted apparently. Furthermore, it also indicates that the incorporation of TSI-POSS is as the rigid core in hybrid composites.
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Rositasari, R., and T. Purbonegoro. "A Retrospective Study of Semi-Enclosed Bays Based on Short Core Samples in Surabaya and Bali, Indonesia." IOP Conference Series: Earth and Environmental Science 789, no. 1 (June 1, 2021): 012017. http://dx.doi.org/10.1088/1755-1315/789/1/012017.
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Genov, Ivan. "Comment on “Holocene sedimentation in the southwestern Black Sea: Interplay between riverine supply, coastal eddies of the Rim Current, surface and internal waves, and saline underflow through the Strait of Bosphorus” by O. Ankindinova, A. E. Aksu, R. N. Hiscott [Marine Geology, 420 (2020) 106092]." Review of the Bulgarian Geological Society 81, no. 2 (2020): 77–88. http://dx.doi.org/10.52215/rev.bgs.2020.81.2.6.
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Ankindinova et al. (2020) describe a series of hydrological events that have led to sedimentation and stratigraphic variations in the gradual sinking of the Black Sea shelf during the Holocene. A key aspect of the study is the attempt to provide a reliable stratigraphic basis for proving of a transgression in the basin throughout the Holocene. However, the conclusions of this approach run counter to the stratigraphic rules: redeposition and significant hiatus in the transgressive phase change of depth of sediment core location (M05-03P) – principle of superposition; merging of transgressive and regressive deposits into a common stratigraphic unit (contradicts the sequential stratigraphy). For this reason, the stability of the conclusion of Ankindinova et al. (2020) for the totally transgressive Holocene development of the Black Sea is doubtful. In addition, the study is based on the interpretation that the increase in the 87Sr /86Sr ratio is solely dependent on ocean water inflow, which is not always correct for enclosed and semi-enclosed basins.
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Petropoulos, A., A. Androni, T. Ntamkarelou, and Ch Anagnostou. "Carbonate and organic carbon content in the recent sediments of Elefsis bay as indicators for the paleoenviromental evolution of the system." Bulletin of the Geological Society of Greece 47, no. 3 (December 21, 2016): 1562. http://dx.doi.org/10.12681/bgsg.10995.
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During the Holocene period Elefsis bay acted as a semi-enclosed system obstructing water circulation. In some areas, sampling has revealed the problems of anoxia that prevails in the bay, which has been worse during the summer months. Analyses undertaken in a core from the bay of Elefsis showed notable changes in carbonate and organic material, which prove the paleo-environmental evolution of the bay. Such changes of carbonate are due to the different deposition of calcium carbonate from biogenic source (probably and from inorganic source). The variation of organic carbon is still a factor of limited water circulation in the bay.
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Troelstra, Simon, Cees Laban, Maarten Prins, Kay Beets, Maarten van Diepen, Lucien Grooteman, Bas Hageman, Leonie Portanger, Sylvain Rumping, and Archana Sadhoeram. "Holocene development of the Marker Wadden area, Lake IJssel (the former Zuider Zee), The Netherlands." Baltica 31, no. 1 (June 15, 2018): 24–34. http://dx.doi.org/10.5200/baltica.2018.31.03.
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Detailed analysis of a core taken within the framework of the Marker Wadden project reveals the sedimentary history of the central part of the Netherlands following the Holocene sea level rise. Grain size and thermogravimetric analyses coupled with micropalaeontological and stable oxygen isotope data provide a solid framework for a detailed reconstruction of the landscape during this time interval. The Pleistocene landscape of fluviatile and aeolian deposits was succeeded by periods of marsh growth, brackish semi-enclosed lakes and tidal flats until a permanent connection with the North Sea was established. Palynological data suggest human activities in the immediate surroundings of the research area.
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Dionne*, Jean-Claude, and Simon Laliberté**. "Horizontal Cylindrical Structures in an Unconsolidated Quaternary Deposit at Saint-Joachim, Near Québec City (Canada)." Géographie physique et Quaternaire 59, no. 1 (October 30, 2006): 75–80. http://dx.doi.org/10.7202/013738ar.
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Abstract Two series of six horizontal cylindrical structures (pipes) were discovered recently in a Late Pleistocene (11‑10 ka BP) emerged delta deposit about 40 km NE of Québec City, Canada. The pipes occur at a depth of 19 m in a slightly oxydized layer of fine sand which is interlayered with two strata of compact blue silty clay, respectively 35 and 45 cm in thickness. The maximum length of the pipes is not known, but the remaining exhumed pipes measure 34 to 59 cm. Their diameter ranges from 6.5 to 14.5 cm. The pipe core generally consists of clean and loose medium to coarse sand whereas the outer ring, made of oxydized fine sand, is semi-consolidated. Pipes are the result of water flow in a permeable sand layer enclosed between two non-permeable layers; water enclosed in a shallow basin created by local collapsing was under hydraulic pressure and forced to drain out on the delta front. These water escape features are possibly the first known site of horizontal cylindrical structures observed in unconsolidated Quaternary sediments.
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Wang, Bin, Huaiyan Lei, Fanfan Huang, Yuan Kong, Fulong Pan, Weidong Cheng, Yong Chen, and Limei Guo. "Effect of Sea-Level Change on Deep-Sea Sedimentary Records in the Northeastern South China Sea over the past 42 kyr." Geofluids 2020 (October 19, 2020): 1–17. http://dx.doi.org/10.1155/2020/8814545.
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We integrated multiple geochemical analysis of a 13.75 m-long core 973-4 recovered from the northeastern South China Sea (SCS) to detect the response of deep-sea sediment archives to sea-level change spanning the last 42 kyr. The age-depth model based on AMS 14C dating, together with the sediment grain size, shows an occurrence of turbidity current at around 14 kyr, which was associated with submarine landslides caused by gas hydrate dissociation. A dominantly terrigenous sediment input was supplied from southwestern Taiwan rivers. By synthesizing environment-sensitive indexes, four distinct stages of paleoenvironmental evolutions were recognized throughout the studied interval. Well-oxygenated condition occurred during the stage I (42.4-31.8 kyr) with low sea-level stand below -80 m, accompanied by flat terrigenous input. The largest amounts of terrigenous sediment input occurred during the late phase of stage II (31.8-20.4 kyr) with the lowest sea-level stand below -120 m because of a short distance from paleo-Taiwan river estuaries to the core location. An occurrence of Ca-enriched turbidity current disturbed the original sediments during the stage III (20.4-13.9 kyr). The stepwise elevated sea-level stand resulted in an enclosed (semi-enclosed) system and contributed to a relatively low-oxygen environment in deep ocean during the stage IV (13.9 kyr—present). Temporal variations of TOC and CaCO3 display contrary pattern synchronously, indicating a decoupled relationship between organic carbon burial and carbonate productivity. Our results highlight that these sedimentary records as reflected in the paleoenvironmental changes in the northeastern SCS were mainly driven by sea-level fluctuations and later, since the mid-Holocene, the strengthening East Asian summer monsoon (EASM) overwhelmed the stable sea level in dominating the environmental changes.
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Sirigu, Antonello Sergej, Federico Gallizio, Giuseppe Giorgi, Mauro Bonfanti, Giovanni Bracco, and Giuliana Mattiazzo. "Numerical and Experimental Identification of the Aerodynamic Power Losses of the ISWEC." Journal of Marine Science and Engineering 8, no. 1 (January 16, 2020): 49. http://dx.doi.org/10.3390/jmse8010049.
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The wave energy sector is experiencing lively years of conceptual innovation and technological advances. Among the great variety of candidates, only a few are going to be able to reach maturity and, eventually, industrial feasibility and competitiveness. The essential requisite for success is the continuous innovation in response to the incremental experience gained during the design and prototyping stages. In particular, the ability to generate detailed mathematical models, representative of every phenomenon involved in the system, is crucial for informing the design and control stages, allowing to maximize productivity while minimizing costs, and inspiring technological breakthrough and innovation. This papers considers the case of the ISWEC (Inertial Sea Wave Energy Converter), where a technological leap is tightly linked with the modelling of aerodynamic losses around its spinning flywheel, the core of the energy conversion chain. Two mathematical models of increasing complexity are considered, one semi-empiric and one based on computational fluid dynamics, which are successfully validated against experimental data. Such models are used to quantify the benefits of a technological innovation consisting of enclosing the flywheel in a sealed container, allowing pressure regulation to reduce aerodynamic friction. Compared to the free configuration, power losses with the enclosed configuration are about half already at atmospheric pressure, and about one third at half the atmospheric pressure.
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Sollai, Martina, Ellen C. Hopmans, Nicole J. Bale, Anchelique Mets, Lisa Warden, Matthias Moros, and Jaap S. Sinninghe Damsté. "The Holocene sedimentary record of cyanobacterial glycolipids in the Baltic Sea: an evaluation of their application as tracers of past nitrogen fixation." Biogeosciences 14, no. 24 (December 22, 2017): 5789–804. http://dx.doi.org/10.5194/bg-14-5789-2017.
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Abstract. Heterocyst glycolipids (HGs) are lipids exclusively produced by heterocystous dinitrogen-fixing cyanobacteria. The Baltic Sea is an ideal environment to study the distribution of HGs and test their potential as biomarkers because of its recurring summer phytoplankton blooms, dominated by a few heterocystous cyanobacterial species of the genera Nodularia and Aphanizomenon. A multi-core and a gravity core from the Gotland Basin were analyzed to determine the abundance and distribution of a suite of selected HGs at a high resolution to investigate the changes in past cyanobacterial communities during the Holocene. The HG distribution of the sediments deposited during the Modern Warm Period (MoWP) was compared with those of cultivated heterocystous cyanobacteria, including those isolated from Baltic Sea waters, revealing high similarity. However, the abundance of HGs dropped substantially with depth, and this may be caused by either a decrease in the occurrence of the cyanobacterial blooms or diagenesis, resulting in partial destruction of the HGs. The record also shows that the HG distribution has remained stable since the Baltic turned into a brackish semi-enclosed basin ∼ 7200 cal. yr BP. This suggests that the heterocystous cyanobacterial species composition remained relatively stable as well. During the earlier freshwater phase of the Baltic (i.e., the Ancylus Lake and Yoldia Sea phases), the distribution of the HGs varied much more than in the subsequent brackish phase, and the absolute abundance of HGs was much lower than during the brackish phase. This suggests that the cyanobacterial community adjusted to the different environmental conditions in the basin. Our results confirm the potential of HGs as a specific biomarker of heterocystous cyanobacteria in paleo-environmental studies.
Dissertations / Theses on the topic "Semi-enclosed core"
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Безкоровайный, Владимир Сергеевич. "Повышение помехоустойчивости феррозондовых дефектоскопов к магнитным полям помех." Thesis, Восточноукраинский национальный университет им. В. Даля, 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/18964.
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Диссертация на соискание ученой степени кандидата технических наук по специальности 05.11.13 – Приборы и методы контроля и определение состава веществ. – Национальный технический университет "Харьковский политехнический институт", Харьков, 2015.
В диссертационной работе решается проблема повышения помехоустойчивости феррозондовых дефектоскопов к магнитным полям помех, вызванных конечными размерами контролируемых деталей, их ступенчатыми и галтельными переходами, магнитной неоднородностью ферромагнитного материала. Анализ существующих методов подавления помехи, вызванной сторонним магнитным полем, показал, что основным способом устранения помехи в настоящее время является включение обмоток феррозондов по градиентометрической схеме. Однако этот метод не свободен от недостатков, так его эффективность низка при высоком уровне градиента поля помехи и коэффициент преобразования феррозонда в большей степени зависит от геометрических параметров магнитной системы и расположения полуэлементов феррозонда относительно дефекта. Не свободен от недостатков метод экранирования феррозонда, так как экран значительно увеличивает размеры преобразователя, что затрудняет его использование на ступенчатой поверхности детали. Обзор методов и способов подавления помехи показал, что наиболее эффективным является метод, основанный на использовании двух феррозондов, один из которых является измерительным, а второй – компенсационным. При этом необходимо, чтобы измерительный феррозонд имел достаточную чувствительность, как к магнитному полю дефекта, так и к полю помехи, а компенсационный феррозонд имел высокую чувствительность только к полю помехи и практически не реагировал на поле дефекта. Для теоретического обоснования эффективности предлагаемого метода была разработана математическая модель поля вектора намагниченности, как в области всей детали, так и в локальной области расположения дефекта. Напряженность магнитного поля в сердечниках феррозонда, индуцированного намагниченностью детали и дефекта, рассчитывается путем применения модифицированной теоремы о взаимности К. М. Поливанова. Сердечники измерительного и компенсационного феррозонда являлись полузамкнутыми U-образной формы. Компенсационный феррозонд имеет перемычку непосредственно над дефектом и шунтирует его магнитное поле. Предложен метод расчета магнитного поля помехи индуцированного намагниченной деталью, основанный на решении интегрального уравнения с использованием линейной аппроксимации функции намагничивания, что сокращает порядок системы алгебраических уравнений. Предложен метод расчета коэффициента передачи мостовой электрической схемы феррозонда, при которой уменьшается вдвое число обмоток и создается возможность получения увеличенного его коэффициента передачи за счет явления параметрического резонанса, упрощается балансировка обмоток феррозонда.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.11.13 – Devices and methods of testing and materials structure determination. – National technical university "Kharkiv Politechnical Institute", Kharkiv, 2015. In the thesis the problem of improving the noise immunity of fluxgate flaw detector to interference’s magnetic fields caused by the finite size of controlled items, their step and fillet connections, the magnetic inhomogeneity of ferromagnetic material has been solved. The method of calculating the magnetic field interference induced by the magnetized part, based on the solution of the integral equation using a linear approximation of the function of the magnetization, which reduces the order of the system of algebraic equations has been proposed. As a transmitter error-correcting ferroprobe flaw is proposed to use a block of the magnetic system consisting of two identical ferroprobes with a U-shaped core. The results of numerical and field experiments have shown that the magnetic flux in the core flux gate with a U-shaped core, with a jumper directly above a defect is 8-12 times smaller than the flow of measurement (main) ferroprobe.
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Безкоровайний, Володимир Сергійович. "Підвищення перешкодостійкості ферозондових дефектоскопів до магнітних полів перешкод." Thesis, Друкарня "Фінвей", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/18960.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.13 – Прилади і методи контролю та визначення складу речовин. – Національний технічний університет "Харківський політехнічний інститут" Харків, 2015.
У дисертаційній роботі вирішується проблема підвищення перешкодостійкості ферозондових дефектоскопів до магнітних полів перешкод, викликаних кінцевими розмірами контрольованих деталей, їх ступінчастими ї галтельними переходами, магнітною неоднорідністю феромагнітного матеріалу. Запропоновано метод розрахунку магнітного поля перешкоди, індукованого намагніченою деталлю, заснований на вирішенні інтегрального рівняння з використанням лінійної апроксимації функції намагнічування, що скорочує порядок системи алгебраїчних рівнянь. У якості вимірювального перетворювача перешкодостійкого ферозондового дефектоскопа пропонується використовувати блок магнітної системи, що складається з двох ідентичних ферозондів з U-подібними осердям. Результати численних і натурних експериментів показали, що магнітний потік в осерді ферозонду з U-подібним осердям, з перемичкою, розташованою безпосередньо над дефектом, в 8-12 разів менше потоку вимірювального (основного) ферозонду.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.11.13 – Devices and methods of testing and materials structure determination. – National technical university "Kharkiv Politechnical Institute", Kharkiv, 2015. In the thesis the problem of improving the noise immunity of fluxgate flaw detector to interference’s magnetic fields caused by the finite size of controlled items, their step and fillet connections, the magnetic inhomogeneity of ferromagnetic material has been solved. The method of calculating the magnetic field interference induced by the magnetized part, based on the solution of the integral equation using a linear approximation of the function of the magnetization, which reduces the order of the system of algebraic equations has been proposed. As a transmitter error-correcting ferroprobe flaw is proposed to use a block of the magnetic system consisting of two identical ferroprobes with a U-shaped core. The results of numerical and field experiments have shown that the magnetic flux in the core flux gate with a U-shaped core, with a jumper directly above a defect is 8-12 times smaller than the flow of measurement (main) ferroprobe.
Book chapters on the topic "Semi-enclosed core"
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Chuong, Nguyen Tien, and Doan Xuan Quy. "On the Thin-Walled Theory’s Application to Calculate the Semi-enclosed Core Structure of High-Rise Buildings." In Lecture Notes in Mechanical Engineering, 866–74. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3239-6_67.
Full textConference papers on the topic "Semi-enclosed core"
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Shukla, Shyam N., and Jagadish Kshirsagar. "Numerical Simulation of Tip Clearance Flow in Semi-Open Impeller Pump." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37355.
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Semi-Open impellers are commonly used for handling fluids with abrasive particles. These impellers have back shroud and the blades do not have support from front shroud. The designer proposes standard clearance to allow free rotation of impellers in stationary casing. Design clearances are difficult to maintain during manufacturing as it calls for special manufacturing process. It is well established in experiments that both head and efficiency decrease with increase in tip clearance and are quite sensitive to rather small change in clearance. It was planned to carry out numerical experiments with such geometry and bring out effect of varying tip clearance on overall performance of pumps with semi-open impellers. In CFD analysis mostly pumps are analyzed with enclosed impeller as rotating component with stationery casing. The meshing of the tip clearance area was a matter of concern. This is overcome using commercial code CFX-Bladegen and CFX-Turbogrid software and good quality mesh of the impeller was prepared. The paper describes the numerical simulation of tip clearance in semi-open impeller pump. The flow pattern showing clearance vortices associated with tip clearance are brought out. Then effect of clearance on the overall performance of pump is established by varying tip clearance.
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Ikoma, Tomoki, Koichi Masuda, Hisaaki Maeda, and Chang-Kyu Rheem. "Hydroelastic Behavior of Air-Supported Flexible Floating Structures." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28090.
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A pontoon type very large floating structure has elastic deformations in ocean waves. The deformation is larger than that of a semi-submergible type one. Thus, a pontoon type one will be installed to tranquil shallow water field enclosed by breakwaters. Moreover, a semi-submergible one will be applicable to development at offshore field. The authors has developed a pontoon type VLFS with an OWC (oscillating water column) type wave energy absorption system. This can be install to offshore field being deep water relatively. Such VLFS can reduce not only the elastic deformation but also the wave drifting forces. However, it is very difficult to reduce the wave drifting forces effectively because an effect of the reduction depends on the wave energy absorption. Therefore, the authors propose an air supported type VLFS. This idea has been already proposed. However, it wasn’t handled a flexible structure. Such an air-supported structure makes to transmit many waves. Therefore, the wave drifting forces may not increase. In addition, the elastic deformation may decrease because pressure distribution due to the incident waves becomes constant at the bottom of the structure, i.e. the pressure is constant in a same air chamber. We develop the program code for the analysis of the hydrodynamic forces on the VLFS with the air cushion. The potential flow theory is applied and the pressure distribution method is used to the analysis of the wave pressures. The zero-draft is assumed in this method. The pressure and volume change of the air cushion are linearized. In this paper, basic characteristics of the elastic deformations of the air-supported flexible floating structures are investigated. We confirm the effectiveness, and discuss behaviors of the water waves in air chamber areas.