scholarly journals Optimization of Aggregates Supply for Concrete Plants

2018 ◽  
Vol 64 (3) ◽  
pp. 99-110 ◽  
Author(s):  
A.K. Nicał

AbstractOver the recent years, there is a growing interest in concrete prefabrication. Many of the currently operating concrete plants have implemented systems that increase the quality of manufactured products, have expanded highly automated production lines and have clearly reduced wastes and energy consumption. However, one of the problems often encountered in the construction industry is the inefficient organization of logistics processes. Proper shipments planning of aggregates consisting of the selection of their appropriate quantity and the aggregate stock, corresponding to the needs of concrete plants should contribute to lowering costs. Therefore, it is necessary to carry out the optimization, the aim of which is to minimize costs, as well as to maximize the fulfillment of the degree of expected needs of concrete plants. This paper presents a model that allows purchase strategy optimization of aggregates with different grain size fraction. For research purposes, three separate aggregate stocks and five different concrete plants are considered.

2007 ◽  
Vol 24-25 ◽  
pp. 229-232
Author(s):  
S.L. Ma ◽  
Wei Li ◽  
Cong Rong Zhu ◽  
J. Zhang ◽  
H.C. Ye

Tungsten carbide which is a hard and brittle material was ground by cast-iron bonded diamond wheel with ELID (Electrolytic In-Process Dressing) technique, for the purpose of getting high efficiency, super-precision machining. Three kinds of cast-iron bonded diamond wheels with different grain size were adopted to get different grinding efficiency and surface quality of workpieces. The grinding properties of cast-iron bonded grinding wheels with different grain size and the ground surface quality of tungsten carbide are discussed in this paper. The experiment results indicate that, under the same feeding amount, the grinding efficiency of the wheel with bigger grain size is higher, and it could make the dimension accuracy of the workpiece controllable, but the wheel with smaller grain size could get better ground surface quality. The two grinding phases are decided by the ratio between the size of abrasive grain and the thickness of the oxide layer on the grinding wheel.


2021 ◽  
Vol 1199 (1) ◽  
pp. 012061
Author(s):  
M Macko ◽  
D Łączny ◽  
J Lewandowski

Abstract This paper presents the results of research on the process of grinding dried corn stalks to use them as polylactide filler. Shredding was carried out on a laboratory shredder with the use of a design variant based on discs with cylindrical holes. By selecting the design variant, the appropriate grinding speed and the material pressure on the shredder discs, the most favourable parameters in terms of the quality of the shredded product and low energy consumption were selected. The research was conducted to reduce the energy demand during the shredding process and to obtain the shredded material suitable for further processing steps.


2019 ◽  
pp. 62-65
Author(s):  
K.N. Tishaninov ◽  
A.V. Anashkin

Зерноочистительные агрегаты зачастую используют поточные технологические линии для послеуборочной очистки зерна, от качества работы которых зависит стоимость конечного продукта и рентабельность всего цикла производства зерна. Разделение потока зерна на две технологические линии происходит с использованием тройника зернопровода, что приводит к перегруженности одной линии и недогруженности другой. Зерноочистительные машины работают за рамками рекомендуемых нагрузок, что приводит к низкому качеству очистки и высокому уровню потерь зерна. Для качественной настройки зерноочистительных машин в составе технологии послеуборочной очистки зерна необходимы устройства для разделения потоков зерна. В ФГБНУ ВНИИТиН разработаны несколько классов авторегулируемых устройств (делителей): с грузовоспринимающей системой, с щелевыми отверстиями и т.д. Нами рассматривается одно из таких устройств делитель потока зерна с горизонтальным размещением щелевых отверстий. Теоретически обоснована взаимосвязь погрешности деления в зависимости от асимметричности подачи зерна в стабилизирующей ёмкости, высоты насыпи, ширины отводящих каналов. Показана кривая распределения погрешности разделения в зависимости от отклонений подачи зерна по ширине и длине ёмкости. На основе теоретического анализа сформулированы рекомендации по технологической настройке и выбору оптимальных конструктивных параметров каскадного делителя.Grain cleaning units often use flow lines for postharvesting cleaning of grain, the quality of work which depends on the cost of the final product and the profitability of the entire cycle of grain production. The separation of the grain flow into two production lines occurs using the tee of the grain pipe which leads to congestion of one line and underloading of the other. Grain cleaning machines operate beyond the recommended loads which lead to poor cleaning quality and high levels of grain loss. For highquality setting of grain cleaning machines as part of the technology of postharvesting cleaning of grain, devices for the separation of grain flows are needed. Several classes of automaticallycontrolled devices (dividers): with a loadperceived system, with slotted openings, etc. are developed in FSBSI AllRussian Scientific Research Institute for the Use of Machinery and Oil Products in Agriculture. One of these devices a grain flow divider with horizontal placement of slotted openings is considered by us. Theoretically, the relationship between the error of division depending on the asymmetry of the grain supply in a stabilizing tank, the height of the embankment, the width of the discharge channels. The distribution curve of separation error is shown depending on the deviations of the grain feed across the width and length of the tank. Based on the theoretical analysis recommendations for technological adjustment and selection of optimal part specifications of a cascade divider are formulated.


Author(s):  
X. Shu ◽  
L. Yang ◽  
B. Wang ◽  
S. Mei

n the traditional twisting process of industrial yarns, the yarn bobbins are transported manually, and long-term labor causes great physical damage to the operators. Therefore, the demand for automated production is very urgent.The conveying process of finished yarns after doffing is an essential part of the design of automated production lines. This article analyzes and designs the finished yarn conveying link, determines the structural design of the mechanism by studying the realization of the fixing device, completes the selection of key components and parameter analysis, and analyze the movement path of the conveyor belt and the force of the finished yarn clamping process.The finished yarn conveying system is mainly composed of two parts. The first half is the conveyor belt in the middle of the machine, and the second half is the fixing device at the rear of the car.


Ergodesign ◽  
2021 ◽  
Vol 0 (3) ◽  
pp. 177-187
Author(s):  
Leonid Chervyakov ◽  
Islam Aleksandrov ◽  
Natalia Bychkova

Aim of the work. The main aim of the analysis is to search for approaches to building an exhaustive epistemological model of the production process as a set of connections to be disclosed and implemented in the automated production, which is a complex anthropotechnical cyberphysical system. Research methods. Digitalization of production inherently involves the solution of three major tasks: digitalizing communications, forming digital models of various objects, developing digital “tools” for decision support. Solving these tasks requires understanding of the deep essence and laws of such a complex system as a production process. This allows looking at the production process as a single interconnected structure (system) of its elements, where ignoring them often leads to a significant decrease in the quality of the design and technological decisions taken and, as a consequence, unjustified costs of various types of resources or non-fulfilment of the set requirements for the manufactured products (item). The interdependence of the objects of the production process allows speaking about the production process connections. Research results and novelty. To ensure the quality of the design and technological decisions taken during the production process digitalization, the former is represented as a system of links that have an “elementary” level of generalization in form and the maximum level of generalization in content. This allows representing the production process as a meaningful set of transition functions to be implemented. Findings. For the purposes of analyzing and building digital production, as a most complex anthropotechnical cyber-physical system, it is advisable to represent the production process in the form of a system of connections, while it should be considered that: 1. The manufactured product in the general case is a combination of three types of relations: dimensional, substantial and economic. 2. To ensure the item connections, a production process must be implemented, which in the general case represents a system of five types of connections: dimensional, informational, temporary, substantial and economic ones. 3. The interdependence of the links between the item and the production process is revealed through the transition functions, which are heterogeneous and indefinite. In addition, when creating a production process and automating it, designers have to face two major challenges: the choice of relations and their organization. Both are fraught with great engineering difficulties. 4. Representing the production process and the finished product in the category of connections is an important epistemological aspect of modelling and understanding the process itself, which allows highlighting and concentrating efforts on its important and essential aspects. At the early stages of design all this already helps to reduce possible errors arising from an incomplete and / or inappropriate representation of the nature and features of this process and, as a consequence, is a certain guarantee of achieving the gradual goal while reducing the necessary costs.


2021 ◽  
Vol 887 ◽  
pp. 516-520
Author(s):  
A.L. Popov ◽  
V.V. Strokova ◽  
A.E. Mestnikov

The modern construction industry is more and more inclined to use composite binders instead of traditional binders. Composite binder is characterized by increased efficiency and environmental friendliness, improved performance characteristics at a reduced cost and energy consumption. Based on this, studies are needed to determine the possibility of using quartz-feldspar sand as a component of composite binders.


2020 ◽  
Author(s):  
Zhongyuan Wang ◽  
Yongqiu Wu

<p>Desert (sandland) margin is the transition region from inner aeolian landforms  to other landforms outside, while it remains as an ambiguous conception in previous researches. Accurately delineating its boundary line and realizing the characteristics of the particle size distribution of surface aeolian sands in margin area can help us understand the formation of modern boundary of desert (sandland). In this research, the criteria of identification of the boundary were proposed and the boundary line was extracted quantitative. Then systematic analyses of grain size of aeolian sand in margin were conducted. Together with the morphologic type, activity and the geomorphological location of collected dunes, the factors controlled the particle-size distributions had also been analyzed. The results reveal the following: (1) There is notable difference in grain size characteristics of aeolian sand between inside and outside of Mu Us sandland. The outside samples are finer than inside. Additionally, the aeolian sand covering on loess is always more poorly sorted and with different grain size fraction composition. (2) The controlling factors on particle size distribution are different in different downwind margins. In southwest margin, the grain size characteristics of aeolian sand are influenced by time and degree of stabilization of sampled dune and locally topographic relief; From the estuary of Lu River to Yuxi River, sediment transport by wind is affected by topographic obstacles including both valley and loess gully. Meanwhile, the small dunefields in Loess Plateau outside of Mu Us sandland may originate from a local alluvial source; In northeast downwind margin, the grain size characteristics of aeolian sand covering on loess are determined by regional gully erosion after its deposition.</p>


2018 ◽  
Vol 40 ◽  
pp. 02009
Author(s):  
Dieter Rickenmann ◽  
Nicolas Steeb ◽  
Alexandre Badoux

Direct bedload samples were taken with a large metal basket at the steep Erlenbach stream in Switzerland. These measurements were compared with the signal of the Swiss impact plate geophone system to derive information about bedload transport. The so-called amplitude histogram (AH) method was developed in an earlier study to estimate the bedload flux for different grain-size classes at the Erlenbach. A new analysis of a larger set of measurements was made here to improve the performance of the AH method. The approach relies on an identification of the transported grain sizes through their dependency on the signal amplitude. As a new element we introduce here the impulse rate, which is found to affect the number of impulses recorded for each amplitude class. As compared to the original method, the new version of the AH method shows a slightly improved performance for total calculated bedload mass, and results in a clearly better agreement between calculated and measured characteristic grain sizes.


2015 ◽  
Vol 229 (9) ◽  
Author(s):  
Dawid Murawski ◽  
Sebastian Roß ◽  
Harald Behrens

AbstractA new cell was developed to study the behavior of powders during axial compaction at temperatures up to 950 K and pressures up to 1 GPa. Electrical conductivity of the sample is measured by impedance spectroscopy. Change of sample volume can be simultaneously monitored using linear variable differential transducers. Flushing with gases allows pre-conditioning of material surfaces before compaction. The cell was tested with two different grain size fractions (60–150 μm and 200–250 μm) of lithium trisilicate glass in the brittle deformation range (315 K) and in the partially plastic deformation range (ca. 660 K). The DC conductivity increases linearly with pressure up to 750 MPa at about 660 K. Lower conductivity for the smaller grain size fraction under these conditions is attributed to higher shares of pores between the grains, acting as resistors.


2016 ◽  
Vol 879 ◽  
pp. 1865-1869 ◽  
Author(s):  
Markus Stütz ◽  
Diogo Oliveira ◽  
Matthias Rüttinger ◽  
Nikolaus Reheis ◽  
Heinrich Kestler ◽  
...  

In the scope of this work, 2 mm thick TZM sheet metal is butt welded by electron beam welding (EBW) without filler material and a systematic investigation of the most relevant welding parameters to improve the weld quality is conducted. With the aid of design of experiment (DoE), it is shown that with careful selection of the welding parameters it is possible to considerably reduce the size of the fusion zone and the heat affected zone and the grain size of both. Furthermore, the influence of the parameters on the quality of the weld and the characterizing values ultimate tensile strength and hardness of fusion zone is presented. It is concluded, which parameters influence the quality of the weld and suppress pores and cracks.


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