Affections of Turbine Nozzle Cross-Sectional Area to the Marine Diesel Engine Working

After a long period of use, some important technical parameters of the main marine diesel engines (MDE) gradually become worse, such as the turbine speed, intake pressure, exhaust temperature, engine power, and specific fuel oil consumption (SFOC). This paper studies the affections of the turbine nozzle cross-sectional area (AT) to MDE and presents a method of AT adjustment to improve the performances of MDE. A mathematical model of an engine was built based on the existent engine construction and the theory of the diesel engine working cycle and the simulation was programmed by Matlab/Simulink. This simulation model accuracy was evaluated through the comparison of simulation results and experimental data of the MDE. The accuracy testing results were acceptable (within 5%). The influences of AT on the engine working parameters and the finding optimization point were conducted by using the simulation program to study. The predicted optimization point of the nozzle was used to improve the engine’s performances on board. The integration of the simulation and experiment studies showed its effectiveness in the practical application of the marine diesel engine field

Applications of Werner Complexes as Chiral Solvating Agents and Catalysts in Enantioselective Synthesis

When NMR spectra of chiral racemic organic molecules containing a Lewis basic functional group are recorded in the presence of air and water stable salts of the cobalt(III) trication [Co((S,S)-NH2CHArCHArNH2)3]3+ ((S,S)-23+ for Ar = Ph), separate signals are usually observed for the enantiomers (28 diverse examples, >12 functional groups). Several chiral molecules can be simultaneously analyzed, and enantiotopic groups in prochiral molecules differentiated (16 examples). Particularly effective are the mixed bis(halide)/tetraarylborate salts Λ-(S,S)-23+ 2X–BArf– (X = Cl, I; BArf = B(3,5-C6H3(CF3)2)4), which are applied in CD2Cl2 or CDCl3 at 1-100 mol% (avg 34 and 14 mol%). Job plots establish 1:1 binding for Λ-(S,S)-23+ 2Cl–BArf– and 1-phenylethyl acetate or 1-phenyl¬ethanol, and ca. 1:2 binding with DMSO (CD2Cl2). Selected binding constants are determined, which range from 7.60-2.73 M–1 for the enantiomers of 1-phenylethanol to 28.1-22.6 M–1 for the enantiomers of 1-phenylethyl acetate. The NH moieties of the C2 faces of the trication are believed to hydrogen bond to the Lewis basic functional groups, as seen in the crystal structure of a hexakis(DMSO) solvate of -(S,S)-23+ 3I–. These salts rank with the most broadly applicable chirality sensing agents discovered to date. The chiral enantiopure cobalt(III) complex -(S,S)-23+ 2Cl–B(C6F5)4– is an effective catalyst, together with pyridine (10 mol% each), for enantioselective additions of substituted cyanoacetate esters NCCH(R)CO2R' to acetylenic esters R"CCCO2R"'. In the resulting adducts, which feature quaternary carbon stereocenters, NC(R'O2C)C¬(R)CR"C=CHCO2R"', C=C isomers in which the CO2R"' moiety is trans to the new carbon-carbon bond dominate (avg. ratio 98:2). These are obtained in 70-98% ee (avg. 86%; data for optimum R' and R"'), as determined by 1H NMR with the chiral solvating agent Λ-(S,S)-23+ 2I–BArf–. NMR experiments show that the cyanoacetate and acetylenic esters and pyridine can hydrogen bond to certain NH groups of the catalyst. Rates are zero order in the cyanoacetate and acetylenic esters as well as the catalyst, and implications are discussed. Exploratory studies were conducted with three additional reactions. First, the reaction of methyl 2-oxocyclopentanecarboxylate with N-fluorobenzenesulfonimide in the presence of Λ-(S,S)-23+ 2Cl–BArf– (10 mol%) gave the monofluorinated product methyl 1-fluoro-2-oxocyclopentanecarboxylate in >99% yield and 79% ee. Second, the Neber reaction of 3-((tosyloxy)imino)butanoate catalyzed by 10 mol% Λ-(S,S)-23+ 2Cl–BArf– in the presence of 2.0 equiv of Et3N gave 3-methyl-2H-azirine-2-carboxylate in >99% yield and 97% ee. Third, intramolecular hydride transfer and cyclization of dimethyl 2-(2-(dialkylamino)benzylidene)malonate gave tetrahydroquinoline products in 50% to >99% yields and 0-82% ee using 10 mol% of the catalyst Λ-[Co((S,S)-NH2CHArCHArNH2)3]3+ 2Cl–BArf– (Λ-(S,S)-3b3+ 2Cl–BArf– for Ar = 1-naphthyl) at 50-80 ℃. Extension of these promising results to other substrates will be studied and communicated in the future. When the complex Λ-(S,S)-23+ 3Cl– was treated with AgF, a new salt Λ-(S,S)-23+ 3F– was obtained in 98% yield. This could be used as the catalyst in the trifluoromethylation of aromatic aldehydes to give trimethylsilyl-1-aryl-2,2,2-trifluoroethanols in 20-70% isolated yields and 54-99% ee. Extension to other aldehydes gave low yields and ee values. The chloride anions in Λ-(S,S)-23+ 2Cl–BArf– was exchanged in situ with anions of the enantiomers of proline to generate the catalyst Λ-(S,S)-23+ 2(proline)–BArf–. The catalyst was used in the addition of acetone to trans-β-nitrostyrene to give the adduct 5-nitro-4-phenylpentan-2-one in 90% yield and 58% ee. Without the proline anions or the cation Λ-(S,S)-23+, lower ee values were obtained

Earthquake Response Analysis and Resistant Design of Moderately Ductile Reinforced Concrete Shear Walls Considering Higher Mode Effects

RÉSUMÉ Des études numériques récentes ont démontré que les exigences des codes actuels peuvent sousestimer les efforts de cisaillement sismique à la base et les sollicitations des forces de flexion sur toute la hauteur des murs de refend en béton armé. Cette situation peut conduire à des ruptures par cisaillement à la base et à la formation de rotules plastiques involontaires dans la partie supérieure des murs. Les sous-estimations des sollicitations sont attribuées à des imprécisions en considérant l'effet des modes supérieurs de vibration (HMEs - higher mode effect) lorsque les éléments structuraux réagissent dans le domaine non linéaire. Des chercheurs ont proposé des méthodes pour prendre en compte les HMEs. Cependant, la plupart des méthodes proposées étaient fondées sur des études numériques utilisant des logiciels d'analyse des structures par éléments finis simples avec des éléments de poutre avec rotules plastiques concentrées aux extrémités, ou des modèles d'éléments finis avec des hypothèses qui n'ont pas été validées à l'aide de l'expérimentation dynamique. En outre, la plupart de ces propositions ont été limitées aux murs de refend situés dans l'ouest de l'Amérique du nord avec des sollicitations sismiques essentiellement de basses fréquences d'environ 2 Hz par opposition aux secousses sismiques de 10 Hz dans l'est de l' Amérique du nord est (ENA). Par conséquent, une étude des HMEs utilisant des modèles constitutifs de murs de refend validés expérimentalement, en considérant des secousses sismiques de hautes fréquences typiques de l'ENA est nécessaire.----------ABSTRACT Recent numerical studies have demonstrated that current code requirements may underestimate the seismic shear at the base and the flexural strength demands along the height of reinforced concrete (RC) shear walls. These may lead to shear failure at base and unintended plastic hinge formation in the upper part of walls. The underestimations of the demands in codes are attributed to inaccuracies in considering higher mode effects (HMEs) when structural walls behave in the nonlinear range. Researchers have proposed methods to consider HMEs. However, most of the proposed methods were based on numerical studies using simple finite element structural analysis program with lumped plasticity beam elements or finite element models with assumptions that have not been validated by using experimental dynamic tests. In addition, most of these proposals were restricted to shear walls located in western North America (WNA) with low dominant frequency around 2 Hz as opposed to 10 Hz for eastern North America (ENA) earthquakes. Therefore, an investigation of HMEs using experimentally verified constitutive shear wall models considering high frequency ENA ground motions is necessary

The taxonomy, zoogeography and ecology of amphibians and reptiles of Hin Nam No National Protected Area (Laos) in comparison with data from Phong Nha – Ke Bang National Park (Vietnam).

In this thesis the mostly unknown herpetofauna in Hin Nam No National Protected Area Laos in the northern Truong Son Range was for the first time intensively investigated, and its diversity was compared to the bordering, and well-investigated Phong Nha - Ke Bang National Park in Vietnam. Twelve new vertebrate species were described comprising 11 geckonids (Cyrtodactylus bansocensis, C. calamei, C. hinnamnoensis, C. jaegeri, C. rufford, C. sommerladi, C. soudthichaki, Gekko boehmei, G. bonkowskii, G. sengchanthavongi, G. thakhekensis, Lycodon banksi and one colubrid snake (Lycodon banksi). Seven species were discovered for the first time in Laos including three frogs (Gracixalus quyeti, G. supercornutus, Rhacophorus maximus), two geckos (Cyrtodactylus cryptus, C. pseudoquadrivirgatus) and two snakes (Lycodon futsingensis, L. ruhstrati abditus). The main hypothesis that the Truong Son Range acted as a biogeographic barrier for the distribution of amphibians and reptiles could be confirmed at least for karst adapted gekkonids. Compared to other herpetofaunal groups the number of gekkonids in karst formations was particularly high (seven bent-toed geckos, four true geckos). By comparing the relative amounts of shared species in Hin Nam No and Phong Nha - Ke Bang, it is interesting to note that fewer reptile species (38%) than amphibian species (66%) were shared between both regions. This might indicate that the Truong Son Range acts as a stronger biogeographical barrier for reptiles than for amphibians. Two pairs of karst-adapted cryptic gecko species (i.e. species with distinct genetic differences, but a similar phenotype) occurred on both sides of the Truong Son Range. Only in one case these were sibling species (Crytodactylus sommerladi in Laos versus C. roesleri in Vietnam), but not in the other (C. hinnamnoensis in Laos versus C. phongnhakebangensis in Vietnam). On the Laotian side, nine gecko species (Cyrtodactylus bansocensis, C. calamei, C. darevskii, C. hinnamnoensis, C. khammouanensis, C. multiporus, C. sommerladi, G. boehmei, G. sengchanthavongi) currently have to be regarded as endemic to the Hin Nam No region. On the Vietnamese side, seven species including two bent-toed geckos (Cyrtodactylus phongnhakebangensis and C. roesleri), three skinks (Lygosoma boehmei, Sphenomorphus tetradactylus and Tropidophorus noggei), and two snakes (Hebius andreae and Boiga bourreti) are currently only known from Phong Nha - Ke Bang and adjacent regions. These high numbers of potential endemic species together with the cryptic species complex in Cyrtodactylus provide strong evidence that the karst formations in the northern Truong Son Range represent a hot spot of reptile diversity and of speciation in Crytodactylus in particular. Correct species identification is a fundamental requirement for conservation measures. The discovery of cryptic species complexes poses a challenge for alpha taxonomy and species conservation, because the true distribution ranges of the species are in fact much smaller than previously assumed. Species conservation in this area of Laos is facing a number of further problems. New and potentially endemic species were discovered in highly populated and disturbed areas. Conversion of the Ho Chi Minh Trail into a highway provided easy access for farmers and still continues to accelerate the destruction of remote forest areas. Southern Hin Nam No with its high diversity of endemic species was identified as the first priority area for conservation. Also Ban Soc, an area isolated from Hin Nam No, should be among the conservation priorities because this region houses a so far overlooked population of the critically endangered Siamese crocodile. Efforts to establish a legal conservation status for this habitat are in progress

Stability-Oriented Dynamics and Control of Complex Rigid-Flexible Mechanical Systems Using the Example of a Bucket-Wheel Excavator

Der Schwerpunkt dieser Arbeit liegt auf der Modellbildung und der Regelung von Schaufelradbaggerauslegern. Die Schaufelradbagger stellen eine besondere Art komplexer Maschinensysteme dar, die im Braunkohletagebau eingesetzt werden. Der Schaufelradausleger ist hierbei als dreidimensionaler elastischer Balken nach der EULER-BERNOULLI Balken-Hypothese modelliert. Durch den Erhalt von Termen höherer Ordnung in den nichtlinearen Relationen zwischen Verschiebung und Verzerrungen, sind Kopplungseffekte höherer Ordnung der gesamtheitlichen Verschiebung und der flexiblen Deformation mitberücksichtigt. Bei der Modellierung der geometrischen Nichtlinearität des dreidimensionalen elastischen Balkens wurde weiterhin die zusätzliche Elastizität von Hebekabeln miteinbezogen. Komplexere Bewegungen, speziell die geführte Bewegung in Kombination mit Grabkräften wurden aufgezeigt und diskutiert. Die Elastizität des Auslegers wurde in Bezug auf die Interaktion zwischen Schneidewerkzeug (Baggerschaufel) und Oberflächenmaterial berücksichtigt. Einflüsse von Kopplungen höherer Ordnung zwischen flexiblen Deformationen, Förderseilen und Grabgegenkräften auf das dynamische Verhalten des Schaufelradauslegers werden mithilfe intensiver Simulationsstudien dargestellt. Dynamische Phänomene, die sich aus den geometrischen und dynamischen Kopplungen höherer Ordnung ergeben, die der geführten Bewegung und den Grabgegenkräften ausgesetzt sind, wurden im Detail analysiert. Die destabilisierenden Einflüsse, die zu großen Deformationen des Systems führen, beruhen auf den oben genannten Kopplungen, werden in den Simulationsergebnissen gezeigt. Das entwickelte Model sowie die damit verbundene Abbildung des dynamischen Systems liefert somit eine gute Basis für weitere Untersuchungen der Systemstabilität in Zusammenhang mit den Grabgegenkräften. Das nichtlineare dynamische System des Schaufelradauslegers wird durch ein erweitertes lineares System mit Nichtlinearitäten eines passenden fiktiven Modells für die Ansteuerungsanalyse und Designzwecke approximiert. Ein PI-Beobachter wird basierend auf diesem erweiterten linearen System eingesetzt, der alle Zustände des Systems schätzen und das Zeitverhalten der Nichtlinearitten rekonstruiert. Von diesem Standpunkt aus ist die beobachtergestützte PI-Zustandsregelung in Kombination mit einer Störungs- Kompensationsregelung realisiert. Drei Störungs-Kompensationsregelungsansätze bestehen aus dem statischen Ansatz, dem Davison Ansatz und dem erweiterten Ansatz nach dem Davison wurden zur Kompensation der Nichtlinearitäten diskutiert. Anhand von Simulationsbeispielen wird die effiziente Unterdrückung von Vibrationen und der Systemstabilisierung des Schaufelradbaggers während des Grabprozesses gezeigt. Die Ergebnisse zeigen, dass der Davison Ansatz und der erweiterte Ansatz nach dem Davison die dynamische Verbesserung des Schwingungsverhaltens sowie Stabilisierung des Schaufelradbaggers gewähren können. Demnach kann die Produktivität und somit die Ertrag des Schaufelradbaggers erhöht werden.The focus of this thesis is the modeling and control of the boom of the Bucket-Wheel excavator, which represents a specific type of complex machine systems used in mining technology. Hereby the Bucket-Wheel boom is modeled as the three-dimensional flexible beam using the Euler-Bernoulli beam theory. Retaining higher-order terms in the nonlinear strain-displacement relationship, higher-order coupling effects between the overall motion and flexible deformations are considered in the modeling. Furthermore, the nonlinear modeling of the three-dimensional elastic boom is also considered with the additional elasticity of hoisting cables. More complex motions, especially the guided motion in combination with digging resistance forces, are mentioned and discussed. So far, the elasticity of the boom along with the interaction between the cutting head and the face material is taken into account. The effects of higher-order couplings between flexible deformations, hoisting cables, and digging resistance forces on dynamical responses of the Bucket-Wheel boom are illustrated by intensive simulation studies. Dynamic phenomena resulting from higher-order geometrical and dynamical couplings undergoing the guided motion and digging resistance forces are therefore analyzed in detail. The destabilizing effects leading to large deformations (may be critical) of the system due to the above mentioned couplings are shown in simulation results. Thus, the developed model as well as the related dynamic system representation gives a good base for the advanced study of the stability of the system in combination with the digging resistance forces. For control analysis and design purposes, the nonlinear dynamical system of the Bucket-Wheel boom is approximated by the extended linear system with nonlinearities modeled by a suitable fictitious model. Based on this extended linear system, a high-gain PI-Observer is applied to estimate all states of the system and to reconstruct the time behavior of the nonlinearities. From this point of view, a high-gain PI-Observer-based state feedback control is realized in combination with disturbance rejection control approaches. Three disturbance rejection control approaches including the static disturbance rejection control approach, Davison approach, and the extended approach of Davison are discussed for compensating nonlinearities. Simulation examples are included to illustrate the efficient suppression of vibrations as well as the stabilization of the system during the digging process of the Bucket-Wheel Excavator. The results show that the static disturbance rejection control approach cannot stabilize the system, while Davison approach and the extended approach of Davison can stabilize successfully the system with the suitable dynamic feedback terms. Consequently, application of these approaches can improve operating ranges of the Bucket-Wheel excavator. Therefore, an exploitation productivity of the Bucket-Wheel excavators can be increased

A new record of Cyrtodactylus soni Le, Nguyen, Le & Ziegler, 2016 (Reptilia: Squamata: Gekkonidae) from Hoa Binh province and threat assessment

A new population of the Son’s Bent–toed Gecko (Cyrtodactylus soni), an endemic species of Vietnam, is reported for the first time from Hoa Binh province based on three adult male specimens collected in June 2018 in a karst cave of Dong Tam commune, Lac Thuy district. The population of this species in Hoa Binh province is threatened by habitat loss through converting forest to agriculture and quarrying of limestone. Assessment of population status in the study area is urgently needed to provide baseline data for conservation measures.

Selection of Exercises to Improve the Effectiveness of Physical Education under the Project of Elective Sports Cockpitching for Female Students K2023 Hanoi Metropolitan University

The interview results have selected 36 exercises belonging to 5 exercise groups to improve the effectiveness of physical education according to the project for female Hanoi Metropolitan University students studying the optional sport of shuttlecock, including Group 1: Exercises to develop strength quickly has 7 exercises; Group 2: Strength development exercises have 6 exercises; Group 3: Exercises to develop endurance has 5 exercises; Group 4: Exercises to develop flexibility and coordination has 5 exercises; Group 5: Exercises with the bridge has 13 exercises with an agreement level of > 70% or more and an average score of > 3.41 - 4.20 points. &nbsp

A Multiple Choices Reading Comprehension Corpus for Vietnamese Language Education

Machine reading comprehension has been an interesting and challenging task in recent years, with the purpose of extracting useful information from texts. To attain the computer ability to understand the reading text and answer relevant information, we introduce ViMMRC 2.0 - an extension of the previous ViMMRC for the task of multiple-choice reading comprehension in Vietnamese Textbooks which contain the reading articles for students from Grade 1 to Grade 12. This dataset has 699 reading passages which are prose and poems, and 5,273 questions. The questions in the new dataset are not fixed with four options as in the previous version. Moreover, the difficulty of questions is increased, which challenges the models to find the correct choice. The computer must understand the whole context of the reading passage, the question, and the content of each choice to extract the right answers. Hence, we propose the multi-stage approach that combines the multi-step attention network (MAN) with the natural language inference (NLI) task to enhance the performance of the reading comprehension model. Then, we compare the proposed methodology with the baseline BERTology models on the new dataset and the ViMMRC 1.0. Our multi-stage models achieved 58.81% by Accuracy on the test set, which is 5.34% better than the highest BERTology models. From the results of the error analysis, we found the challenge of the reading comprehension models is understanding the implicit context in texts and linking them together in order to find the correct answers. Finally, we hope our new dataset will motivate further research in enhancing the language understanding ability of computers in the Vietnamese language

CAMELLIA SPHAMII (THEACEAE, SECT. PIQUETIA), A NEW TAXON OF YELLOW FLOWER FROM LANGBIANG BIOSPHERE RESERVE, VIETNAM

Camellia sphamii is described and illustrated as a new species of section Piquetia from Hamasin village, D’ran town, Don Duong district, Lam Dong province, Vietnam. C. sphamii is similar to C. proensis (Quach, Luong et al., 2021) but differs from it in several morphological features: mature leaves cordate at base, young leaves purple; pericarp 7–8 mm thick with dense hair on the outer surface, flower buds ovate, ferruginous; sepals 5, hemisphere, concave, finely hairy on the outer surface, sparsely hairy on the inside, petals 7, finely hairy on the outer surface, with translucent margin, concave; style 5, ½ basally united; capsule 5 locular. Information on its phenology, distribution, ecology, and conservation status is also provided

Evaluation of genetic diversity and DNA fingerprinting of 19 standard reference rice varieties using SSR markers

Molecular markers are advanced-tools for identifying new varieties at DNA levels. According to the International Union for the Protection of New Varieties ofPlants,  new breeded varieties need to be tested for the Distinctness, Uniformity and Stability (DUS), before being recognized as the new ones. Traditional DUS criteria based on 62 - 65 morphological and biochemical characteristics, which evaluated on comparison of new varieties with 19 standard reference varieties for traits of interest.  Study on the genotypic polymorphism of 19 standard reference rice varieties provides genotypic information of these varieties for the evaluation of new rice varieties based on genotyping analysis.  The reference marker set (30 markers) was used to evaluate the genetic diversity and DNA fingerprinting of 19 standard reference rice varieties. The results showed the similarity coefficient of 19 varieties varied from 0.04 to 0.548. At the genetic similarity coefficient of 0.1, the 19 rice varieties divided into two main groups. Group one included 3 varieties: DH1, DH5, DH13. Group 2 included the remaining 16 varieties. Inside group two, phylogenetic tree divided into two main branches at the genetic similarity coefficient of 0.3. Branch 1 includes 5 varieties including DH2, DH6, DH10, DH11 and DH7. The 11 remaining varieties were in the branch 2. The most closely varieties were DH6 and DH10 with the genetic similarity coefficient of 0.548. This study shows that, the standard reference varieties have high uniformity and high genotypic polymorphism, could used for testing new varieties based on genotyping by DNA fingerprinting combining with phenotype