Papers by Keyword: Packing

Abstract: The disadvantage of high-strength multicomponent concretes is the high absolute and specific consumption of the binder per unit of strength. The object of research is multicomponent cement systems. The subject is the composition of multicomponent cement systems in order to significantly increase the concentration of the solid phase per unit volume, as well as strength and durability. The creation of a dense, highly filled solid phase in the form of heterogeneous mineral modifiers of a homogeneous dispersed structure ensures the production of high strength concretes with a low binder content. Theoretical and practical studies have shown that there are only three levels of dispersion of mineral modifiers, functionally related to the spatial and geometric parameters of the clinker component and its own pozzolanic activity, providing strength and other construction and technical properties of multicomponent cement systems at the maximum level. The properties and structure of concrete were studied using two fractions of fine aggregate, granite-gabro crushed stone fr. 5-10 mm, Portland cement class CEM I 42.5N, finely dispersed blast-furnace granular slag, microsilica, highly dispersed fraction of cement, superplasticizer Glenium 430 and high-valence hardening accelerator. Research methods: the shape and size of dispersed particles of the components were determined by a laser analyzer, the mobility of the concrete mixture in accordance with GOST 10181–2014, the strength of concrete in accordance with GOST 10180–2012. The structure of the cement stone was studied using scanning microscopy, thermographic and X-ray phase analysis methods. The strength of concrete with an optimized disperse composition, a superplasticizer and a high-valence hardening accelerator at the age of 28 days after hardening under normal conditions was 128; 137; 163 MPa, with the consumption of multicomponent cement, respectively 650, 700, 750 kg / m³.

Abstract: Tessellation methods are a relatively new approach for modeling the structure of a material. In this paper, such structures are interpreted as sphere packing models, where molecules and atoms represent spheres of equal or different size. Based on the review of the literature, it is shown that the tessellation approach is a powerful method for modeling and simulating such structures with desirable metric and topological properties. Two basic tessellation methods are considered more in detail: the Delaunay tessellation and the Voronoi diagram in Laguerre geometry, as well as some of their generalizations. The principal concepts of both tessellation methods are briefly explained for a better understanding of the application details. It is noted that packing models created by tessellation methods are not based on the use of the gravity camp effect, which is a difference to numerical and mathematic programming modeling approaches. Therefore, tessellation methods permit the development of structures without taking into account the gravitation, what is important for modeling the structure on the microscopic and nano levels, where the influence of the gravitation is studied insufficiently. A review of the related literature is given, focusing on the details of the tessellation method and the particle size distribution.

Abstract: This paper summarize idealized theoretical studies of bicomponent particle packing parameters, affecting the phase and pore structure of obtained materials. Such a kind of analysis can be used both in theoretical consideration of material engineering problems and in chemical industry. The effects of key variables on the relationship between packing fraction and particle size were re-examined for general application. Potential applications of these results include synthesis of nanopaterials, adsorbents, catalyst carriers and packing for chromatographic columns. Directions for future research are suggested.

Abstract: The actual NP-completed orthogonal bin packing problem is considered in the article. In practice a solution of a large number of different practical problems, including problems in logistics and scheduling comes down to the bin packing problem. A decision of an any packing problem is represented as a placement string which contains a sequence of objects selected to pack. The article proposes a new multilevel linked data structure that improves the effectiveness of decoding of the placement string and as a consequence, increases the speed of packing generation. The new data structure is applicable for all multidimensional orthogonal bin packing problems.

Abstract: The actual in industry strip packing problem which is NP-hard in strong sense is considered in paper. To the strip packing problem comes down solution of a large number of different practical problems, including problems in logistics, scheduling and planning. The new heuristics intended to pack a given set of rectangular two-dimensional objects in order to minimize of the total length of the filled part of container with an infinity length and fixed width are offered. The proposed multimethod genetic algorithm is investigated on well-known standard benchmarks of two-dimensional strip packing problems.

Abstract: Three different structural types of closed cooling tower (CCT) and two cooling water flow directions were considered. The experimental study were done on the cooling performance of influences of inlet air dry and wet bulb temperature, cooling water flow rate and inlet temperature, air flow rate and spray density. The experimental results show that the cooling performance of CCT with packing is obviously better than non-packing cooling tower in 7%~18.4%. And the cooling performance of CCT with packing on top and coil underneath is slightly better than CCT with coil on top and packing underneath in 4.9%. In the same conditions the cooling performance of CCT with packing under cooling water cocurrent-flow is better than that cooling water countercurrent-flow in 3.2%~9.6%. Therefore, the closed cooling tower structure with the cooling water path in bottom and out top, and with packing on top and coil underneath is recommended.

Abstract: The port section intersecting lines of circular-pipes are complicated space curves in multi-pipe intersecting structures, which makes it is difficult to treat circular-pipes for packing pipe precisely by traditional algorithm. A new decoding algorithm is proposed by dividing and translating points of intersecting lines in pipes’ port sections and calculating the least surrounding boxes of them. Encoding and decoding method and evaluation mode of fitness function are given. And responding packing module based on this decoding algorithm is developed in AutoCAD. It demonstrates that using the decoding algorithm can improve the utilization rate of materials and make programming efficient and easy.

Abstract: Beginning during the decade of 1920, the Brazilian highway system became the main way of transportation in the country, fomenting the search for asphaltic mix with better mechanical properties and resistance to the weather variations. The asphaltic mix is formed by minerals aggregates and binder (PAC Petroleum Asphaltic Cement). The aggregates are responsible for supporting the traffic weight and stability. The PAC is responsible for the attachment between the constituent particles and impermeable state. In this work it was investigated the formulation of asphaltic mix starting from the packing equations of the particles: Andreasen, Alfred and Alfred Inverted. It was produced bodies of proof varying the proportions of the aggregates and fillers, keeping constant the PAC (5% in weight) and the results were compared to an industrial standard formulation. The values obtained are in accordance with the DNIT norms, indicating that the equations of packing can be applied to the formulation of asphaltic masses.

Abstract: The multidimensional NP-hard orthogonal bin packing problem is considered in the article. Usually the problem is solved using heuristic algorithms of discrete optimization which optimize a selection sequence of objects to be packed in containers. The quality and speed of getting the resulting packing for a given sequence of placing objects is determined by the used packing representation model. In the article presented a new packing representation model for constructing the orthogonal packing. The proposed model of potential containers describes all residual free spaces of containers in packing. The developed model is investigated on well-known standard benchmarks of three-dimensional orthogonal bin packing problem. The model can be used in development of applied software for the optimal allocation of orthogonal resources.

Abstract: China have the biggest biogas yield in the world, but biogas quality is low and the utilizations of biogas are monotonous now, the shorting of appropriate upgrading technologies is impeding the developing and high quality using of biogas. With analog biogas as raw material, this study investigated biogas upgrading by water scrubbing with adsorption materials used for scrubber picking. Three sorts of packing-plastic hollow sphere, clay ring and zeolite pellet were chosen for the test and the experiments were operated under various pressures (0.65MPa、0.5MPa and 0.3MPa). The results showed that the adsorption packing could improve biogas upgrading effect, the removal rate of CO2 were better when use zeolite pellet( which have better adsorption) as packing compared with conventional plastic hollow sphere, and the results of clay ring(which have little adsorption) experiments were between the above two.