Principle Of Expansion Research Articles

Characteristic parameters and radon exhalation rates of aerated concrete blocks

ObjectiveTo understand the characteristic parameters and radon exhalation rates of aerated concrete blocks. MethodsA total of 39 nationally inspected samples were measured. Their dry density was determined based on their mass and volumes, their porosities were measured on the principle of volumetric expansion, and their radium content was determined using a high-purity germanium (HPGe) detector for gamma-ray spectroscopy. Furthermore, their diffusion lengths were quantified by establishing a combined cumulative and diffusion chamber, and their radon exhalation rates were measured through closed-box testing using a continuous radon monitor. ResultsThe aerated concrete blocks exhibited dry densities ranging from 464 to 840 ​kg/m3 [average: (654.0 ​± ​82.5) kg/m3], open porosities from 67.1 ​% to 81.1 % [average: (74.3 ​± ​3.3) %, radium (226Ra) content from 12.3 to 136 Bq/kg [average: (63.0 ​± ​30.4) Bq/kg], diffusion lengths from 0.49 to 1.01 ​m [average: (0.70 ​± ​0.15) m], and radon exhalation rates from 0.6 to 22.8 Bq·m−2·h−1 [average: (7.3 ​± ​5.3) Bq·m−2·h−1]. ConclusionAerated concrete blocks exhibit significantly higher porosities, diffusion lengths, and radon exhalation rates than traditional concrete and clay bricks. These blocks might contribute to the high indoor radon concentration observed in modern buildings in China.

A novel coupled algorithm for Studying the performance characteristics of water ramjet in the flight of supercavitating vehicle

When a supercavitating vehicle performs a flight, the water ramjet of the vehicle exploits the water in the surrounding environment as an oxidiser and is inevitably affected by the vehicle motions. In this study, the characteristics of the performance change in a water ramjet were investigated when a supercavitating vehicle performs a flight to gain more insights into the design of underwater power systems. Given the principle of independent cross-section expansion of cavities, a longitudinal ventilated supercavity model was built to predict the development of a ventilated cavity and its interaction with the body. A thermal calculation model was developed based on the minimum free energy method to calculate the performance parameters of water ramjets. A novel coupling algorithm was proposed based on the aforementioned model to integrate the motion of a supercavitating vehicle with the operation of a water ramjet. The integration described above was achieved by linking the water intake and body motion and calculating the performance change characteristics of the water ramjet during the flight of the supercavitating vehicle. The operating characteristics of the water ramjet with changes in the designed water-fuel ratios were investigated to provide a basis for exploring the unperturbed flight of the vehicle, depth regulation, and underwater environmental changes. The thrust of the water ramjet is less affected by external factors, and its performance feedback tends to exacerbate external disturbances at a designed water-fuel ratio lower than the optimal water-fuel ratio. A water ramjet with a designed water-fuel ratio higher than the optimal water-fuel ratio has a rapid response time, adaptive thrust, and stable combustion chamber pressure. External disturbances slightly affected the thrust and combustion chamber pressure of the water ramjet when the designed water-fuel ratio was equal to the optimal water-fuel ratio. The results of this study provide technical support for optimising the design of water ramjet.

Analysis of numerical modeling of steady-state modes of methane–hydrogen mixture transportation through a compressor station to reduce CO2 emissions

This study presents a mathematical model to evaluate the performance of gas pipelines during hydrogen injection in a gas pipeline-compressor station. The developed model presents the calculation of methane–hydrogen mixture (CH4/H2) transportation through the compressor station, where the compensation of pressure drops in the mass and energy balance takes place. Simultaneously, in the operation of the centrifugal blower system of gas compressor stations, the emissions of CO2 are considered, considering the mixing of gas media and the compression of CH4/H2. This mathematical model is realized for the pipeline transportation of hydrogen, at which the principle of mixture expansion occurs. The aim is to solve the problem of CO2 emissions at compressor stations. The optimization procedure has been formulated using a system of nonlinear algebraic equalities. The research focuses on the adaptation of existing gas transportation systems to CH4/H2 transportation and the impact of environmental risks on the operation of compressor station equipment. In this case, it is possible to determine the quantitative amount of hydrogen that can be added to natural gas. By solving the problem of finding the inner point of sets using the system of nonlinear algebraic equalities, it is possible to obtain the control parameters for safety control of technological modes of CH4/H2 mixture transportation. The study findings reveal that the consumption of gas charger and hydrogen was 50.67 and 0.184 kg/s, respectively, and the estimated efficiency resulting from the modified turbine design was 75.1 percent. These results indicate that the equipment operates more efficiently when hydrogen is being transported. The numerical analytical results indicated in this study hold practical significance for design applications. It will assist in identifying and evaluating the restrictions that may develop during the technological, operational, and design stages of decision-making.

An innovative iterative approach to solving Volterra integral equations of second kind

Many scientists have shown great interest in exploring the realm of second-kind integral equations, offering many techniques for solving them, including exact, approximate, and numerical methods. This paper introduces the Hussein-Jassim method (HJ-method) for solving Volterra integral equations of the second kind (VIESKs). The foundation of this approach lies in the principle of Maclaurin expansion. The algorithm of the method was derived, and its convergence was analysed. Furthermore, the method was applied to various Volterra integral equations, encompassing linear, nonlinear, homogeneous, and nonhomogeneous cases. Ultimately, the proposed method successfully addressed these equations, with the approximate solutions converging toward the exact solution.

Приближенный синтез оптимальных детерминированных систем управления с неполной обратной связью на основе достаточных условий ε-оптимальности

<p>The problem of optimal control of deterministic dynamical systems in the absence of information about a part of the coordinates of the state vector is considered. Sufficient ε-optimality conditions based on the principle of expansion are formulated and proved. An algorithm is proposed for finding an a priori estimate of the proximity of the synthesized control law with incomplete feedback to the optimal one for a given set of initial states. The solution of the model example is given.</p>

Analysis of Principle and Applications of Series Expansion

Analysis of Principle and Applications of Series Expansion

Joining of EN AW 6060 Pipes by Plastic Forming

The article deals with an innovative, but not widely used type of joining of aluminum pipes through experiments. The joints are formed by plastic forming. The process is carried out in one step using the principle of pipe expansion, in order to bring the mating surfaces of the two pipes into a suitable position for the subsequent joining, which is created by means of plastic instability and simultaneous pressure flanging. Experimental tests were carried out with the tools designed to create most suitable joints. The length of the plastically formed pipe sections involved in the joint, the angle of the sharpened pipe ends, and the thickness of the formed joints were analyzed. One of the main goals of this study is to determine the proper joining parameters, such as tool distance or edge tapering for further investigations. As per the test results, it can be stated that the technology is suitable for joining aluminum tubes in a cost-effective way, and based on the promising strength results, further investigations will be conducted.

Asymptotic approximations for Generalized Apostol-Bernoulli, Apostol-Euler and Apostol-Genocchi Polynomials in terms of Hyperbolic Functions

Asymptotic approximation formulas for polynomials of the type Apostol-Bernoulli, Apostol-Euler and Apostol-Genocchi with integer order and real parameters are obtained via hyperbolic functions. The derivation of the formulas is done using the principle of saddle point and expansion of appropriate hyperbolic function about a saddle point.

Modeling the properties of multilayer heat-reflecting screens taking into account the uncertainty of structural parameters

The article is devoted to the study of parametric properties of multilayer heat-reflecting screens. Special attention is paid to the parameters of shielding and heat flow absorption. The study, its numerical and analytical techniques ensure that the fuzzy input situation is taken into account. The fuzziness is generated by the variance of both the values of geometric parameters and the actual values of structural elements. The proposed analytical and numerical research techniques are applicable in a wide range of productions of thermal protective products – for the energy industry, radio electronics, aerospace instrumentation, production of building structural elements. The theory of fuzzy sets is actively applied in terms of the heuristic principle of expansion. It is the basis for regular versions of the presented models. The underlying calculations are based on fuzzy numbers that represent exogenous parameters.

Dynamic Tensile Mechanical Properties of Outburst Coal Considering Bedding Effect and Evolution Characteristics of Strain Energy Density

The evolution of strain energy density of outburst-prone coal is of great significance for analyzing the characteristics of energy accumulation and release in coal and rock masses. The dynamic mechanical properties of coal samples were tested by using the split Hopkinson pressure bar (SHPB) technique. Dynamic tensile mechanical properties, layered effect and density evolution characteristics of strain energy for coal were studied. The dynamic failure and crack propagation process of the specimen were recorded with a high-speed camera. In addition, a digital image correlation (DIC) method was used to analyze the evolution characteristics of the strain field during the deformation process of the specimen. The distribution characteristics of the particle fragments were statistically analyzed. The results show that the bedding orientation of the coal has a significant effect on its deformation and damage features. The presence of weak planes, microcracks and laminae causes its shear damage zone to behave more complex. If the crack plane coincides with the high shear stress plane, the developed shear cracks extend along the weak laminae and the shear damage zones in BD specimens are not symmetrically distributed. When the laminated surface of the coal sample is at a certain angle with the impact loading direction, the damage mode is coupled with tensile and shear damage. The percentage mass distribution of particles and fines increases with increasing bedding orientation. The effect of water on the dynamic damage of coal samples is significant. Based on the principle of pressure expansion of wing-shaped cracks, the formula for calculating the dynamic strength of water-saturated coal samples under dynamic loading was derived.

Solving a puzzle of definition

ABSTRACT This paper concerns the question of which logical principles hold for real definitions. Recently, Samuel Elgin has presented five principles concerning real definitions that seem initially plausible. He has shown them to be jointly inconsistent. This gives rise to a puzzle that can only be solved by denying one of the principles. In this paper, I argue against Elgin's principle of expansion, which concerns substituting a definiens for its definiendum within the definiens of a further definition. I show that this principle fails for every irreflexive notion of definition and proposes a replacement that allows to restore consistency and solve the puzzle.

The Demarcation of Urban Development Boundary Based on the Maxent-CA Model: A Case Study of Wuxi in China

With the rapid development of urbanization, the demarcation of the urban development boundary (UDB) is of great practical significance to curb the disorderly spread of urban land, avoid losing control of urban development space, and build a barrier to green development space. In this paper, we propose a method to support the demarcation of the UDB by combining the Maxent model and the cellular automata (CA) model. This approach comprehensively considers the relationship between urban construction suitability, neighborhood effect, spatial constraint, and random interference based on a spatio-temporal dynamic simulation. This contributes to the analysis of the driving mechanism and distribution pattern of urban expansion. According to the principle of scale expansion and centralization, the simulation result is modified to demarcate the UDB. The following conclusions are drawn: the Maxent-CA model can intuitively reflect the driving mechanism and accurately simulate urban expansion in specific cities, which contributes to demarcating the UDB. Considering that this method fully embodies the principle of combining top-down and bottom-up approaches in the demarcation of UDB, we argue that the Maxent-CA model is of vital importance for the sustainable development of the living environment and is of great reference value for territorial spatial planning.

Humanitarian bullets and man-killers: Revisiting the history of arms regulation in the late nineteenth century

AbstractIn 1899, the delegates at the first Hague Peace Conference outlawed the use of expanding bullets in warfare. Also known as “dum-dum” bullets, their prohibition was largely the product of a media spectacle that evolved around their use in British colonial warfare, a spectacle that focused particularly on the ghastly nature of the wounds these bullets inflicted. This article revisits the “dum-dum” controversy of the 1890s as it played out in the Anglo-European public sphere. It argues, firstly, that there was nothing all that innovative about employing the principle of expansion in rifle ammunition. Secondly, it shows that controversies around bullets and their wounds had existed since the invention of industrially produced military rifles – and soft-lead ammunition – in the 1850s. In 1868, the St Petersburg Declaration outlawed the use of exploding projectiles for many of the same reasons for which expanding ammunition would also be banned in 1899. The article also shows that many of the ideas mobilized in the early 1890s to promote a new range of cordite-powered full-metal-jacket bullets because of the supposedly “clean” and “humanitarian” wounds that they inflicted offer an important context in which to read and explain the prohibition of “man-slaying” expanding ammunition. Above all, the article highlights how powerful racist thinking and imperial imperatives were to the framers of the laws of war at the turn of the twentieth century.

THE STORY OF SACRIFICE IN THE QUR’AN AND THE BIBLE: JULIA KRESTEVA’S INTERTEXTUAL APPROACH

This paper discusses the story of the sacrifice carried out by Prophet Ibrahim in the Qur’an. The story in question is narrated in the Qur’an and the Bible. The story of Abraham’s sacrifice is significant in finding the similarities and differences between the two. Therefore, the approach used in this research is intertextual, initiated by Julia Kristeva, who tries to compare the narrative or interpretation between the two. Using this approach, many differences were found. This study concludes that the sacrifice narrated in the Qur’an by the author is divided into three fragments, the initial fragment, namely the sacrifice commandment, has the principle of expansion and haplology; the fragment of the sacrificial process itself has the principle of haplogy, and the last fragment is the principle of expansion and modification.

지역기반 세계지역학습을 위한 AI기반 챗봇의 개발과 활용: 문화 다양성 이해를 중심으로

This study developed an AI chatbot for place-based microlearning in Haeundae to help learners build knowledge of global region and applied it to the class. The results of big data analysis techniques for identifying regions and topics for the place-based microlearning were Southeast Asian countries and cultural topics such as food, art, performances, and tourism etc. In regards to the results of the big data analysis, a total of 1,070 questions and answers were created as microcontents including texts, and photos, maps, and videos to serve the purpose of learning global regions. The results of the study indicated that learners could learn how closely the Haeundae area, where they live, is connected with many countries in Southeast Asia, in terms of food, clothing and shelter, which students are difficult to understand in traditional classroom environments. In addition, learners showed high level of understanding and satisfaction in the study because the classroom activities were self-directed, customized, individualized. Appying the principle of flexible space expansion to the classroom activity resulted in creative learning and overcoming the limitation of textbooks. The study showed that the learners were able to cultivate the qualities of global citizenship of living together in the complexity of global similarity and differences.

Nanogap Formation Using a Chromium Oxide Film and Its Application as a Palladium Hydrogen Switch.

Developing high response hydrogen sensors manufacturable in a large scale is desirable in hydrogen industry. In this study, a chromium oxidation-based nanogap formation process was developed to fabricate a hydrogen switch with suspended palladium and gold films having a tens of nanometer-sized gap. The nanogap was formed by using oxidized chromium as a self-alignment shadow mask. The hydrogen switch operates by the principle of volume expansion of palladium upon exposure to the hydrogen gas and the current reading by closing of a nanogap formed between suspended palladium and gold films. Further improvement of the sensor performance was achieved by optimizing the design parameters such as suspended film lengths and thicknesses. The fabricated palladium nanogap hydrogen sensor showed an ultrahigh sensitivity of ΔI/I0 > 108 with a fast response time (22 s) to 4% hydrogen. The complementary metal-oxide-semiconductor-compatible fabrication of the hydrogen switch is easily scalable with low manufacturing cost.

Analisa Unsur-unsur Tafsir Jalalain sebagai Teks Hipogram dalam Tafisr Al-Ibriz

This paper will try to examine al-Ibriz's interpretation and Jalalain's interpretation with an intertextual approach, but within the scope of the researcher, the researcher will only try to examine the Surah Maryam verses 1 to 15 with the formulation of the problem, first: What are the elements of Jalalain's interpretation contained in the interpretation al-Ibriz on the interpretation of the letter Maryam verses 1 to 15? Second: What are the principles used by K.H Bisyri Mustafa in processing Jalalain's interpretation as his hypogram text on the interpretation of Maryam verses 1 to 15? From the results of the analysis, the researchers found the elements of Jalalain's interpretation contained in al-Ibriz contained in verses 1,3,5,6,7,12, and 13. As for the principles used to process the hypogram, several principles were found, namely the principle of transformation , haplology, expansion and parallel.

Hyperfine structure S state of muonic helium atom

In this work the nonrelativistic ionization energies 3He2+μ−e− and 4He2+μ−e− of helium-muonic atoms are calculated for S states.The estimates are based on the variational principle of exponential expansion. Convergence of the numerical values of variational energies is studied by increasing a number of the basis functions N. That allows to claim that the obtained energy values have 30-33 significant digits for S states

Detection of Various Types of Metal Surface Defects Based on Image Processing

Machine vision is a promising technique to promote intelligent production. It strikes a balance between product quality and production efficiency. However, the existing metal surface defect detection algorithms are too general, and deviate from electrical production equipment in the level of response time to the target image. To address the two problems, this paper designs a detection algorithm for various types of metal surface defects based on image processing. Firstly, each metal surface image was preprocessed through average graying and nonlocal means filtering. Next, the principle of the composite model scale expansion was explained, and an improved EfficientNet was constructed to classify metal surface defects, which couples spatial attention mechanism. Finally, the backbone network of the single shot multi-box detector (SSD) network was improved, and used to fuse the features of the target image. The proposed model was proved effective through experiments.

Study on the Geo-Stress Loading and Excavation Unloading Devices of the Large-Scale Photoelastic Model Test for Deep-Buried Tunnels

At present, theoretical analysis, numerical simulation, and other methods cannot be used to properly solve the problems associated with the stability and bearing capacity of the surrounding rock and its supporting system, the interaction between the supporting structure and surrounding rock, and the sharing role of each supporting structure, all of which commonly occur in deep tunnels. The model test method represented by the photoelastic test is still an important approach to study this kind of problem. In view of the deficiency of the current loading system of the photoelastic model test, we developed a geo-stress loading system for the photoelastic model test, which can simulate the in situ geo-stress environment of unidirectional loading, bidirectional equal pressure, bidirectional unequal pressure, and tridirectional unequal pressure. The universal retaining force loading rod can realize the stability and effective compensation of loading, which is an original design. According to the principle of umbrella-shaped expansion and contraction mechanism, an excavation unloading device for the photoelastic model test is developed, which can realize the simulation of various degrees of displacement release in the excavation process of deep tunnels and other underground projects. The loading simulation test and excavation unloading simulation test show that the geo-stress loading system and excavation unloading device developed in this paper are flexible, exhibit good performance, and can fully achieve their respective test functions. The combination of two devices can compensate for the insufficiency of the current photoelastic model test and will promote the application of photoelastic model tests in underground engineering applications such as deep tunnel projects.