scholarly journals Investigation findings of acceleration of rigid floating containers

Author(s):  
Г.В. Кудрявцев ◽  
С.В. Посыпанов

Экономическую доступность значительной части лесных ресурсов в основных лесных регионах страны можно обеспечить только при использовании густой речной сети, состоящей преимущественно из средних и малых рек. Значительную роль при этом могут сыграть судовые перевозки. Баржи, обычно используемые для перевозки лесоматериалов по внутренним водным путям, из- за больших размеров не применимы на малых, а при снижении уровней и на средних реках. На указанных реках предлагается использовать баржевые составы, размеры которых можно варьировать в соответствии с конкретными путевыми условиями посредством изменения количества контейнеров или баржевых модулей (БМ), устанавливаемых в баржевой состав. Для выполнения инженерных расчетов, связанных с перемещением БМ и баржевых составов, нужны сведения о сопротивлении воды их движению. Целью настоящей работы является получение информации, необходимой для определения параметров движения БМ в процессе его разгона. Метод исследования – экспериментально- теоретический. В ходе теоретических исследований выявлены факторы, влияющие на процесс разгона БМ в воде и определяющие величину интервального коэффициента фиктивного увеличения его массы (КФУМ). Проведены экспериментальные исследования на моделях по плану второго порядка. По их результатам получена регрессионная модель для интервального КФУМ БМ при его разгоне. Вычислив с ее помощью величину означенного коэффициента, можно, воспользовавшись известными формулами, определить параметры движения БМ при его разгоне. В результате анализа модели установили, что в рассмотренных случаях интервальный КФУМ Ф линейно возрастает с увеличением числа Фруда. Интенсивность указанного возрастания становится больше при увеличении осадки БМ, то есть при уменьшении его относительной ширины. С увеличением относительной длины БМ коэффициент Ф уменьшается. Уменьшается он и с увеличением степени завершенности процесса разгона. Степень и характер влияния определяющих факторов на результат существенно зависят от их взаимодействия. Достоверно оценить указанное влияние в каждом конкретном случае можно лишь выполнив расчеты, соответствующие определенному сочетанию факторов. Economic accessibility of a significant part of forest resources in the main forest regions of the country can be provided only by using a dense network of rivers, consisting mainly of medium and small rivers. Shipments can play significant role in this. Typically, the barges are used for the transport of timber along inland waterways, because of their large size are not applicable at the small rivers and at medium sized rivers during periods of low water level. On these rivers proposed to use barge train, which dimensions are determined by the given river conditions. Their dimensions are determined by the number of containers or barge module (BM) installed in the barge train. Engineering valuations of a BM and barge train are based on information concerning water resistance to motion of a body. The goal of the work: derivation of information for determining the parameters motion during acceleration of the BM. The method of investigation: experimental-theoretical. In the course of theoretical studies determination the factors that influence the process of acceleration of a BM in water and determine the value interval coefficient of imaginary mass increment (CIMI). Experimental studies were carried out on model according to the quadric plan. The regression model of the interval coefficient of imaginary mass increment (CIMI) of a BM during its acceleration were worked out. Cognition of the coefficient allows to determine the parameters motion of a BM in the mentioned conditions. As a result of the analysis of the model, it was established that the interval coefficient of imaginary mass increment (CIMI) Ф linearly increases with increasing Froude number Fr. The intensity of this increase becomes larger with increasing draught of BM, that is, with a decrease in its relative width. The increase of relative length of the BM causes decrease of the coefficient Φ. It also decreases with increasing degree of completeness process of acceleration. The influence degree and pattern of the determining factors depend significantly on their interaction. To estimate this influence it is possible to perform calculations corresponding to a certain combination of factors.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shenghan Gao ◽  
Thibault Broux ◽  
Susumu Fujii ◽  
Cédric Tassel ◽  
Kentaro Yamamoto ◽  
...  

AbstractMost solid-state materials are composed of p-block anions, only in recent years the introduction of hydride anions (1s2) in oxides (e.g., SrVO2H, BaTi(O,H)3) has allowed the discovery of various interesting properties. Here we exploit the large polarizability of hydride anions (H–) together with chalcogenide (Ch2–) anions to construct a family of antiperovskites with soft anionic sublattices. The M3HCh antiperovskites (M = Li, Na) adopt the ideal cubic structure except orthorhombic Na3HS, despite the large variation in sizes of M and Ch. This unconventional robustness of cubic phase mainly originates from the large size-flexibility of the H– anion. Theoretical and experimental studies reveal low migration barriers for Li+/Na+ transport and high ionic conductivity, possibly promoted by a soft phonon mode associated with the rotational motion of HM6 octahedra in their cubic forms. Aliovalent substitution to create vacancies has further enhanced ionic conductivities of this series of antiperovskites, resulting in Na2.9H(Se0.9I0.1) achieving a high conductivity of ~1 × 10–4 S/cm (100 °C).


2020 ◽  
Vol 28 (1) ◽  
pp. 104-120
Author(s):  
Tibor Pecsics ◽  
Miklós Laczi ◽  
Gergely Nagy ◽  
Tamás Kondor ◽  
Tibor Csörgő

AbstractParrots (Psittaciformes) are a unique and diverse avian group and vary tremendously in size, shape, and colour. Mainly distributed throughout the tropics and subtropics, most species of parrots are largely or exclusively arboreal with several exceptions. The species also differ in diet and habitat, which led to different musculoskeletal adaptations of the skull. However, parrots have conspicuous generalized external features; in this recent study, we tried to increase our knowledge of the cranial shape and foraging habits. A geometric morphometric approach was used to analyse two-dimensional cranial landmarks. We used principal component (PC) analyses on measurements that may be related to diet. The PCs described the relative height of the cranium, the relative length and curvature of the beak, differences in the orientation and curvature of the lacrimal bone and the upper margin of orbits, variation in the size and position of the palatine bone and the relative width of the cranium, and variation in the relative size of the neurocranium compared to the viscerocranium. The dietary categories overlap in the morphospace but the analysis in lateral and ventral view resulted in significant differences.


2010 ◽  
Vol 97-101 ◽  
pp. 4247-4250 ◽  
Author(s):  
Wan Li Liu ◽  
Zhan Kui Wang

Laser tracker system (LTS) is an advanced 3D coordinates measuring system for large size. It can measure large 3D coordinates with advantages of broad range, high speed and high accuracy. However, when the size of having been measured large-scale part (such as airplane and shipbuilding) is larger than the LTS measuring range, it can not measure all of the required features of components in one location, which profoundly affect the LTS measuring scope and accuracy. In order to solve measuring problem for large-scale parts, a new method of frog-jumping is proposed based on the principle of using LTS to measure more than three frog-jumping spheres under the new and old coordinate system. The corresponding mathematical model of frog-jumping is established. Intensive experimental studies have been made to check validity of proposed method; the results show that using this technology the measurement of large-scale parts all features is realized effectively under the required accuracy constraints.


2015 ◽  
Vol 93 (9) ◽  
pp. 687-700 ◽  
Author(s):  
Jeremy A. Goldbogen ◽  
Robert E. Shadwick ◽  
Margo A. Lillie ◽  
Marina A. Piscitelli ◽  
Jean Potvin ◽  
...  

Whales are important model systems for understanding the physiological and ecological consequences of extreme body size. However, whales are also some of the most difficult animals to study because their large size precludes experimental studies under controlled conditions. Here we review a wide range of morphological studies that enable greater inference of physiological processes. In particular, we focus on baleen whales that exhibit extensive diving and foraging adaptations. Using morphological data, we (i) explore the biomechanics and sensory physiology of lunge-feeding rorqual whales (Balaenopteridae), (ii) determine the effects of scale and diving pressures on the circulatory physiology of fin whales (Balaenoptera physalus (L., 1758)), and (iii) better understand the adaptations of the cetacean respiratory system that facilitate a fully aquatic life history. These studies underscore the value of understanding functional morphology in animals that cannot be studied using traditional laboratory techniques.


Author(s):  
L. Shustik ◽  
◽  
N. Nilova ◽  
T. Gaidai ◽  
S. Stepchenko ◽  
...  

The purpose of the research is to investigate the quality of spring-finger harrow surface tillage to provoke the germination of carrion depending on the angle of the fingers. Research methods: theoretical – analysis of information resources and research results of spring harrows; laboratory-field – economic tests of the machine with planning of experiment, fixing of agrotechnical indicators; instrumental measurements; mathematical and statistical – processing of the obtained indicators and expert evaluation. Results. Experimental field studies of the quality of surface tillage with a spring-finger harrow were carried out in order to provoke the emergence of winter rapeseed. It was found that the harrow loosens and mulches the top layer of soil well, creating optimal conditions for the germination of weeds and weed seeds. The importance of the agrotechnical measure of field litter management and prospects for the use of spring-finger harrows in the system of soil-protective agriculture is analytically substantiated. Conclusions. The physical parameters obtained as a result of researches of a spring-finger harrow testify that at speed about 20 km / h with increase of an angle of inclination of spring fingers depth of their course increases in 1,6 times from 7,2 cm to 11,3 cm that corresponds to agricultural requirements to spring harrows (4-12 cm). The quality of soil crushing in terms of agronomically valuable aggregates up to 0-25 mm in size increases with satisfactory to excellent values with increasing angle of inclination of the fingers. The results of experimental studies show that the heavy spring-finger harrow Degelman Strawmaster SM 7000-50, in the presence of freshly cut rapeseed stubble of large size and clumps of chaff, provides satisfactory tillage, promoting the germination of rapeseed seeds and improving phytosanitary conditions for future field operations.


2012 ◽  
Vol 7 (3) ◽  
pp. 84-95
Author(s):  
Mikhail Khodakov ◽  
Aleksandr Zarvin ◽  
Valeriy Kaljada ◽  
Nikolay Korobeishchikov

We describe a new experimental facility LEMPUS-2, which provides experimental research in supersonic flows of gases and gas mixtures in the oil-free vacuum. Model experiments in a flow of pure argon in order to verify and test the diagnostic equipment of set-up were performed. Experimental studies of the formation of cluster beams of methane and argon-methane mixtures have been performed to determine the optimal conditions for the formation of intense molecular beams of methane clusters. We obtain an intense molecular beam of methane clusters. It was found that in a supersonic jet of large size pure methane clusters are not diagnosed by the mass spectrum of oligomeric fragments, whereas in mixtures of argon with small admixtures of methane is recorded in the mass spectrum, apparently as oligomers of methane and mixed clusters of argon-methane . It was confirmed that the clustering of methane starts at lower pressures of inhibition than argon and lead to further delay of cluster formation in argon. It is shown that for high intensity methane clusters fluxes should be used specially selected gas mixtures


2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Shaojuan Su ◽  
Tianlin Wang ◽  
Chunbo Zhen ◽  
Fan Zhang

The ultimate strength of the pressure-resistant shells is degraded due to corrosion pit on the surface of the shells. The underwater glider is prone to pit corrosion damage after working in the water for a long time. This study is aimed at development of an assessing formula for ultimate strength of pressure-resistant shells with pit damage. Firstly, a parameterized geometry model of the pit is determined under the assumption that the pits are elliptical. Secondly, a finite element numerical simulation model is established and the numerical simulation results are analyzed to find that the effect of pit damage on the pressure-resistant shell is obvious. Thirdly, the influences of some parameters (relative length, relative width, and relative depth) of pit on the ultimate strength are studied. The regular curve of the influence of geometric parameters on ultimate strength is drawn. Lastly, the ultimate strength assessment formula of pressure-resistant shells was obtained from the data by nonlinear FEM based on the regression function of multiple nonlinear regression analysis by nonlinear regression analysis function regress which can provide the foundation to assess the ultimate strength of damaged pressure-resistant shells.


Author(s):  
Gillian Wright ◽  
Stephen Fallows

Consumer demands for food are determined by a wide variety of factors including: taste acceptability, whether the product is easily available, perceptions of quality and the price. Over time demands change as the determining factors (above) alter. Milk is a perishable food which is purchased daily and therefore is particularly susceptible to changes in demand. Furthermore, because of the large size of the milk industry in Britain, any relatively small percentage change in consumer demand can result in substantial alterations to the volume consumed.


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