Статті в журналах з теми "High energy impact compaction"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: High energy impact compaction.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "High energy impact compaction".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Jiang, Chunlin, Yanhui Ge, Baoqun Wang, Luchen Zhang, and Youbo Liu. "Impact of the High-Energy Dynamic Compaction by Multiple Compactors on the Surrounding Environment." Advances in Civil Engineering 2021 (November 29, 2021): 1–19. http://dx.doi.org/10.1155/2021/6643064.
Повний текст джерелаАнотація:
Dynamic compaction machine (DCM) is a widely adopted ground reinforcement technology. However, dynamic compaction energy has a very significant impact on the surrounding environment. At present, the research on the impact of dynamic compaction mainly focuses on the effect of the tamping behavior of a single compactor in the working state, whereas the research on the impact of multiple compactors working jointly is rare. To study the impact of the dynamic compaction energy of multiple compactors working jointly on the surrounding environment, the dynamic response model for multiple compactors working in the same field was established based on the explicit dynamic analysis module in ABAQUS. The validity of the model was verified by comparison with the measured data. Based on this, the impact of the dynamic compaction energy of multiple compactors with different working conditions in terms of the arrangement, spacing, and working time interval was analyzed. The results showed that the arrangement and spacing of the compactors had a remarkable influence on the distribution of the dynamic compaction energy in the surrounding environment. Under the condition of multiple compactors working with a time interval of less than 10 s, the impact of the superimposed dynamic compaction energy due to the interaction of multiple compactors had to be considered.
2
Tomasi, Roberto, Adriano A. Rabelo, Adriana S. A. Chinelatto, Laudo Reis, and Walter J. Botta Fo. "Characterization of high-energy milled alumina powders." Cerâmica 44, no. 289 (October 1998): 166–70. http://dx.doi.org/10.1590/s0366-69131998000500003.
Повний текст джерелаАнотація:
The utilization of reactive high-energy milling has been reported for the synthesis of ceramic powders namely, metal oxides, carbides, borides, nitrides or mixtures of ceramics or ceramic and metal compounds. In this work, high-energy milling was used for reduction of alumina powders to nanometric particle size. The ceramic characteristics of the powders were analyzed in terms of the behavior during deagglomeration, compaction curves, sintering and microstructure characterization. It was observed that the high energy milling has strong effect in producing agglomeration of the nanosized powders. This effect is explained by the high-energy impact of the balls, which may fracture particles or just cause the particles compacting. In this case, strong agglomerates are produced. As the powder surface area increases, stronger agglomerates are produced.
3
Chen, Jin, Zhi Yu Xiao, Chao Jie Li, San Cai Deng, Tung Wai Leo Ngai, and Yuan Yuan Li. "High Velocity Compaction of 316L Stainless Powder." Applied Mechanics and Materials 44-47 (December 2010): 2993–97. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2993.
Повний текст джерелаАнотація:
High velocity compaction technology was used to press 316L stainless powders. Effects of impact times on stress wave, green density and ejection force were analyzed. It was found that under the same total impact energy, the first loading time and the actuation duration of the second impact in double impact process were longer when compared with single impact process, while the first delay time was shorter. Furthermore, the green density of compacts prepared by double impact was greater than that prepared by single impact, but no obvious variation in maximum ejection force can be observed between single impact and double impact process.
4
You, Dongdong, Dehui Liu, Hangjian Guan, Qingyun Huang, Zhiyu Xiao, and Chao Yang. "A Control Method of High Impact Energy and Cosimulation in Powder High-Velocity Compaction." Advances in Materials Science and Engineering 2018 (July 29, 2018): 1–11. http://dx.doi.org/10.1155/2018/9141928.
Повний текст джерелаАнотація:
To enhance the impact energy of powder high-velocity compaction (HVC) and thus improve the green density and mechanical properties of the resulting compacts, a mechanical energy storage method using combination disc springs is proposed. The high impact energy is achieved by modifying existing equipment, and the hydraulic control system is developed to implement the automatic control of the energy produced from the disc springs. An interdisciplinary cosimulation platform is established using the ADAMS, AMESim, and LabVIEW software packages to perform the interactive control of the simulation process and the real-time feedback of the simulation results. A mechanical-hydraulic cosimulation of the energy control virtual prototype of the testing machine is conducted using this platform. The influence of the impact energy on the green density is studied according to the HVC experimental results of the iron-based powders, and then, the green compact with the higher relative density is produced. The experimental results indicate that the energy enhancement method using the combination disc springs is reasonable and that the hydraulic control scheme is reliable.
5
Xu, Chao, Zhong-qing Chen, Jun-shi Li, and Yuan-yuan Xiao. "Compaction of Subgrade by High-Energy Impact Rollers on an Airport Runway." Journal of Performance of Constructed Facilities 28, no. 5 (October 2014): 04014021. http://dx.doi.org/10.1061/(asce)cf.1943-5509.0000469.
Повний текст джерела
6
Bonicelli, Alessandra, Maurizio Crispino, Filippo Giustozzi, and Melanie Shink. "Laboratory Analysis for Investigating the Impact of Compaction on the Properties of Pervious Concrete Mixtures for Road Pavements." Advanced Materials Research 723 (August 2013): 409–19. http://dx.doi.org/10.4028/www.scientific.net/amr.723.409.
Повний текст джерелаАнотація:
Pervious concrete is a relatively new material, standards and rigorous specifications for construction and placement are therefore still missing. One the one hand, the main characteristic to achieve is a high permeability to allow meteoric water percolate in the pavement and evaporate from the subgrade. On the other hand, developing pavement cementitious mixtures able to retain high void contents and reach significant mechanical performance entails an in-depth analysis of materials and construction practices. Pervious concrete can indeed be placed using a standard paver as for asphalt mixtures but the compaction stage is usually demanded to the contractor practices: light steel hand-rollers or standard drum rollers are both used without an in-depth knowledge of compaction properties of the cementitious mixture. The present paper aims at investigating the influence of compaction methods on the mechanical performance and void contents of pervious concrete mixtures. Several compaction procedures were tested modifying the compaction energy and the mixture characteristics while preserving high permeability. The main objective was to simulate and identify the effect of commonly adopted in situ compaction techniques - i.e.: tamper compaction as provided by the paver, steel hand-roller compaction, or standard drum roller compaction. Results showed how the compaction energy, water/cement ratios, and the percentage of cement affect the Indirect Tensile Strength and void contents of the mixtures. Further investigations were also conducted in order to comprehensively evaluate how the variation in the percentage of cement and water/cement ratio influenced the stiffness of the material.
7
Jayawickrama, Priyantha W., Aruna L. Amarasiri, and Pedro E. Regino. "Use of Dynamic Cone Penetrometer to Control Compaction of Granular Fill." Transportation Research Record: Journal of the Transportation Research Board 1736, no. 1 (January 2000): 71–80. http://dx.doi.org/10.3141/1736-10.
Повний текст джерелаАнотація:
Granular material is commonly used as backfill and embedment material for buried structures, including thermoplastic pipe. Proper compaction of this material is crucial to the successful performance of the pipe. However, the commonly used Proctor density approach cannot be used for the field compaction control of these materials because it does not provide a well-defined moisture-density relationship. An alternative method used by the authors for compaction control of such materials is described. This method involves a device known as the dynamic cone penetrometer (DCP). Findings are presented from a series of DCP tests conducted on a range of granular backfill materials that belong to ASTM D 2321 Classes I and II. These materials were compacted using ( a) an impact rammer and ( b) a vibratory plate compactor. The level of compaction energy was varied by changing the number of passes. The data obtained from these tests are presented in the form of DCP blow count profiles, which are then used as the basis for comparison between different materials, compaction equipment, and levels of compaction energy. A series of full-scale load tests conducted on high-density polyethylene (HDPE) pipe installations is also described. An overview is provided of how the DCP data may be combined with load-deflection data from full-scale load tests to establish guidelines for compaction control of pipe backfill.
8
Sano, Yukio. "Multiple Shock Compaction of Simple Type Powders by Punch Impact." Journal of Energy Resources Technology 114, no. 2 (June 1, 1992): 117–38. http://dx.doi.org/10.1115/1.2905931.
Повний текст джерелаАнотація:
Recently, we have elucidated some mechanical behaviors of powders during the compaction. The elucidation involves the constitutive relations of a powder medium under the multishock compaction, the qualitative behavior such as the similarities of the compaction processes, the die wall friction effect, and the uniformity of the final density distribution of the compact with a high density, and the quantitative behavior analyzed by the pseudo-viscosity method and the shock fitting. This review describes this behavior systematically.
9
Page-Dumroese, Deborah S., Martin Jurgensen, and Thomas Terry. "Maintaining Soil Productivity during Forest or Biomass-to-Energy Thinning Harvests in the Western United States." Western Journal of Applied Forestry 25, no. 1 (January 1, 2010): 5–11. http://dx.doi.org/10.1093/wjaf/25.1.5.
Повний текст джерелаАнотація:
Abstract Forest biomass thinnings, to promote forest health or for energy production, can potentially impact the soil resource by altering soil physical, chemical, and/or biological properties. The extent and degree of impacts within a harvest unit or across a watershed will subsequently determine if site or soil productivity is affected. Although the impacts of stand removal on soil properties in the western United States have been documented, much less is known on periodic removals of biomass by thinnings or other partial cutting practices. However, basic recommendations and findings derived from stand-removal studies are also applicable to guide biomass thinnings for forest health, fuel reduction, or energy production. These are summarized as follows: (1) thinning operations are less likely to cause significant soil compaction than a stand-removal harvest, (2) risk-rating systems that evaluate soil susceptibility to compaction or nutrient losses from organic or mineral topsoil removal can help guide management practices, (3) using designated or existing harvesting traffic lanes and leaving some thinning residue in high traffic areas can reduce soil compactionon a stand basis, and (4) coarse-textured low fertility soils have greater risk of nutrient limitations resulting from whole-tree thinning removals than finer textured soils with higher fertility levels.
10
Cotton, Matthew, and John Maw. "High Strain Rate Compaction of Porous Materials – Experiments and Modelling." EPJ Web of Conferences 183 (2018): 02016. http://dx.doi.org/10.1051/epjconf/201818302016.
Повний текст джерелаАнотація:
Porosity can be found in many forms in common materials, either naturally occurring such as wood, or introduced by a manufacturing process. Applications for such materials include impact protection and energy absorption, which require a good understanding of their response to rapid loading. In order to increase confidence in simulations of porous materials under different loading conditions it is important to validate models with experimental data. To support this requirement experiments have been conducted to investigate the compaction behaviour of porous copper samples in the high strain rate regime. Gas gun plate impact trials with impact velocities in the range 100-300 m/s were used to achieve the conditions of interest. Simulations of the experiments were conducted with a focus on accurately modelling the material response in the region prior to complete compaction. This work will report on the experimental technique and the modelling approach employed to achieve good agreement with the data.
11
Sadek, Younes, Tayeb Rikioui, Toufik Abdoun, and Abdellah Dadi. "Influence of Compaction Energy on Cement Stabilized Soil for Road Construction." Civil Engineering Journal 8, no. 3 (March 1, 2022): 580–94. http://dx.doi.org/10.28991/cej-2022-08-03-012.
Повний текст джерелаАнотація:
Compactness is an important feature to ensure subgrade stability where temperature and water infiltration exist in semi-arid areas. Chemical soil stabilization can improve soil properties. This research studies the impact of compaction energy on stabilized subgrade soil and how to improve its geotechnical characteristics in the experimental tests on both unstabilized and stabilized soil samples by adding ordinary Portland cement and sulfate-resistant cement, in percentages by the soil's weight, in order of identification and classification, to the strength properties tests: compaction at multiple energies, CBR, and UCS. A test protocol was followed to assess the relationship between cement soil treatment, mechanical characteristics, and compaction parameters at different energy levels. Findings show that the higher UCS values were recorded with an increase in compaction energy. The MDD of cement stabilized soil increases as compaction energy increases, whereas the OMC decreases, the UCS improves, and the CBR increases. These improvements have a positive influence on the performance of soil used as a subgrade. The combination of cement stabilization and a high compaction level for subgrades using weak soil can improve strength parameters throughout any phase of earthwork construction design that leads to strengthening subgrades, reducing the thickness, and, as a result, low construction cost. Doi: 10.28991/CEJ-2022-08-03-012 Full Text: PDF
12
Nurek, Tomasz, Arkadiusz Gendek, Kamil Roman, and Magdalena Dąbrowska. "The Impact of Fractional Composition on the Mechanical Properties of Agglomerated Logging Residues." Sustainability 12, no. 15 (July 29, 2020): 6120. http://dx.doi.org/10.3390/su12156120.
Повний текст джерелаАнотація:
Fractional composition, as well as the temperature of the agglomeration process, affect the quality and mechanical properties of briquettes. In this research, shredded forest logging residues were investigated. Compaction tests were carried out for several specially prepared mixtures made of shares of fractions with different particle sizes. The moisture content, density of briquettes, specific work of compaction, mechanical durability, and biomass susceptibility to compaction were analyzed. Studies have confirmed the significant impact of the fractional composition of compacted biomass on its susceptibility to process parameters and the quality of the final product. Statistical analysis confirmed that the density of the briquette, its durability, the specific work of compaction, and the susceptibility of the tested biomass to compaction strongly depend on the particle size of the compacted biomass. An increase in temperature to 73 °C increased specific work by 40% and contributed to the high quality of briquettes in the range from 0.768 to 1.14 g·cm−3.
13
Lian, Xiaoyong, Jun Li, Housheng Jia, and Peng Ding. "The Anti-Impact Characteristics of Cables under Impact Load." Energies 16, no. 2 (January 5, 2023): 633. http://dx.doi.org/10.3390/en16020633.
Повний текст джерелаАнотація:
The cable plays a vital role in roadway support. As the last barrier to prevent roof collapse and impact disaster accidents, it is of great significance to study stress characteristics of cables under impact dynamic load to guide the rock burst roadway support. With high-strength cables of Ф21.6 and Ф21.8 mm and low-resistance high-extension cables of Ф21.5 mm as examples, this paper studied the instantaneous mechanical state and energy dissipation characteristics of different types of cables under impact loads by using impact testing machines and high-frequency data acquisition system. The results show that the impact process can strengthen the strength of the cable. The strength and elongation of anchor cables are a pair of characteristic indexes with an inverse relationship. Simply increasing one index cannot improve the overall impact resistance of the cable. To quantitatively characterize the impact resistance and energy absorption effect of cables, the impact resistance index k was introduced. The smaller the index, the better the energy absorption effect of cables. In the process of dynamic load impact of high-strength cable, about 43.7% of the total energy is dissipated disordered in the form of mechanical energy. The dynamic load impact process of low-resistance and high-extension cables is similar to the viscoelastic impact. In the collision compaction stage, the force of the cable is basically constant. Most of the impact energy is absorbed or transformed by the cable, about 17.7% of which is mostly dissipated in the form of mechanical energy. The disordered dissipated mechanical energy is less, so the impact resistance and energy absorption effect of this cable are better. The cable plays an important role in the process of bearing the dynamic load of surrounding rock. The anti-impact performance index of cables should be considered in dynamic load impact roadway support design.
14
Gonthier, Keith A., and Venugopal Jogi. "Multiscale Shock Heating Analysis of a Granular Explosive." Journal of Applied Mechanics 72, no. 4 (February 8, 2005): 538–52. http://dx.doi.org/10.1115/1.1934666.
Повний текст джерелаАнотація:
A multiscale model is formulated and used to characterize the duration and amplitude of temperature peaks (i.e., hot spots) at intergranular contact surfaces generated by shock compaction of the granular high explosive HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). The model tracks the evolution of both bulk variables and localized temperature subject to a consistent thermal energy localization strategy that accounts for inelastic and compressive heating, phase change, and thermal conduction at the grain scale (grain size ∼50μm). Steady subsonic compaction waves having a dispersed two-wave structure are predicted for mild impact of dense HMX (porosity ∼19%), and steady supersonic compaction waves having a discontinuous solid shock followed by a thin compaction zone are predicted for stronger impact. Short duration hot spots having peak temperatures in excess of 900K are predicted near intergranular contact surfaces for impact speeds as low as 100m∕s; these hot spots are sufficient to induce sustained combustion as determined by a two-phase thermal explosion theory. Thermal conduction and phase change significantly affect hot-spot formation for low impact speeds (∼100m∕s), whereas bulk inelastic heating dominates the thermal response at higher speeds resulting in longer duration hot spots. Compressive grain heating is shown to be largely inconsequential for the range of impact speeds considered in this work (100⩽up⩽1000m∕s). Predictions for the variation in inelastic strain, pressure, and porosity through the compaction zone are also shown to qualitatively agree with the results of detailed mesoscale simulations.
15
Shtertser, Alexandr, Boris Zlobin, Victor Kiselev, Sergei Shemelin, Arina Ukhina, and Dina Dudina. "Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder and Properties of the Compacts." Materials 15, no. 19 (September 27, 2022): 6706. http://dx.doi.org/10.3390/ma15196706.
Повний текст джерелаАнотація:
Experiments on Cyclic Impact Compaction (CIC) of UHMWPE powder GUR 4120 were carried out on a laboratory hydro-pneumatic impact device. This device provides impact energies of up to 1 kJ with a frequency of impacts of 9 s−1 and enables producing dense and robust compacts in the form of disks with a diameter of up to 60 mm and a height of up to 24 mm. The optimal parameters of the CIC were determined, which are the preheating temperature of the powder, the impact energy and the number of impacts. The strength, Brinell hardness and elongation of the resulting compacts with a diameter of 40 mm and a height of 15 mm were 37.5 MPa, 49.0 MPa and 470%, respectively. The possibility of activating UHMWPE powder by explosive loading was studied. It was found that the explosive pretreatment reduces the mechanical properties of the resultant compacts. The CIC method is suitable for the manufacture of UHMWPE-based composites with nano-additives, as evidenced by the successful production of compacts containing nanoscale detonation carbon as an additive. The results of the present study show that the CIC method is promising for the industrial production of small-sized UHMWPE parts.
16
Li, He, Yuanbo Li, Minyu Wei, and Yi Shen. "Preparation Method of Lunar Soil Simulant and Experimental Verification of the Performance of an Impact Penetrator for Lunar Soil Exploration." Machines 10, no. 7 (July 21, 2022): 593. http://dx.doi.org/10.3390/machines10070593.
Повний текст джерелаАнотація:
The exploration and investigation of lunar soil can provide necessary information for human beings to understand the Moon’s geological evolution history and solar activity, and is also of great significance for human beings to search for new energy sources. The impact penetrator can dive to a certain depth below the lunar surface, depending on soil compaction effect, and obtain lunar soil detection data by using the onboard sensors. The penetrator has the advantages of small size, light weight, low power consumption and long-term detection ability. In order to verify the diving performance of the developed impact penetrator, a great deal of lunar soil simulant, with physical and mechanical properties similar to a real lunar soil sample, was prepared, which lay the foundation for experimental research. Experiments on the influences of mass–stiffness parameters and dynamic parameters were conducted to obtain reasonable parameter-matching effects and driving parameters. The penetrating experiments in lunar soil simulant, with different relative compaction parameters, indicated that the penetrator could penetrate the simulated lunar soil with high relative compaction, and the penetration depth could reach to 545 mm after 894 shocks in lunar soil, with a relative compaction of 85%. This study on the impact penetrator can provide a feasible approach for in-situ exploration of lunar soil.
17
Li, Xi, Jing Li, Xinyan Ma, Jidong Teng, and Sheng Zhang. "Numerical Study of the Dynamic Compaction Process considering the Phenomenon of Particle Breakage." Advances in Civil Engineering 2018 (December 23, 2018): 1–10. http://dx.doi.org/10.1155/2018/1838370.
Повний текст джерелаАнотація:
Dynamic compaction (DC) is commonly used to strengthen the coarse grained soil foundation, where particle breakage of coarse soils is unavoidable under high-energy impacts. In this paper, a novel method of modeling DC progress was developed, which can realize particle breakage by impact stress. A particle failure criterion of critical stress is first employed. The “population balance” between particles before and after crushing is guaranteed by the overlapping method. The performance of the DC model is successfully validated against literature data. A series of DC tests were then carried out. The effect of particle breakage on key parameters of DC including crater depth and impact stress was discussed. Besides, it is observed that the relationship between breakage amount and tamping times can be expressed by a logarithmic curve. The present method will contribute to a better understanding of DC and benefit further research on the macro-micro mechanism of DC.
18
Xue, Yongming, Bing Dai, Ying Chen, Lei Zhang, Guicheng He, and Zhijun Zhang. "Experimental Study on the Mechanical Properties and Damage Evolution of Hollow Cylindrical Granite Specimens Subjected to Cyclic Coupled Static-Dynamic Loads." Geofluids 2020 (September 22, 2020): 1–14. http://dx.doi.org/10.1155/2020/8881936.
Повний текст джерелаАнотація:
To study the characteristics of roadway surrounding rock damage caused by frequent disturbances under different static stress conditions, cyclic impact tests on granite with vertical holes under different axial prestress conditions were performed by a modified split Hopkinson pressure bar test, and the damage of the specimens was recorded with a high-speed camera process. The test results show that under the same air pressure cyclic impact, the rock specimens mainly undergo the compaction-fatigue-failure transition. As the axial prestress increases, the compaction-fatigue phase gradually weakens, and the dynamic compressive strength decreases. When the axial prestress is 42% of the UCS and 62% of the UCS, the rock specimen shows a certain “strengthening” effect during the initial cyclic impact stage. During the failure of the rock specimens, the axial prestressing effect limited the initiation of some transverse cracks, and a mixed tensile-shear failure mode appeared. The rock specimens with an axial prestress of 62% of the UCS showed energy release during cyclic impact. To some extent, the probability of “rock bursts” has been induced. Based on the one-dimensional stress wave theory, the damage variables of wave impedance during the cyclic impact loading of the rock with vertical holes are defined. It is found that when the rock specimen is in the stage of compaction and fatigue damage, the damage is small, and the damage is even reduced.
19
Abdul Rahman, Abdul Samad, N. Sidek, Juhaizad Ahmad, N. Hamzah, and M. I. F. Rosli. "Comparative Study in Method of Compaction by Consolidated Drained and Direct Shear Test." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 78, no. 2 (December 10, 2020): 143–52. http://dx.doi.org/10.37934/arfmts.78.2.143152.
Повний текст джерелаАнотація:
Soil compaction has been a common practice in the construction of highways, embankments, earth dams and other related structures where the condition of the soil is high in void ratio and therefore having a very low in bearing capacity. Therefore, the soil needs to be compacted in order to minimize the void ratio and in the same time would results in having a very high bearing capacity to sustain load. Nevertheless, only a few researches have been done to investigate the method of compaction using different energy on the behavior of shear strength by consolidated drained and direct shear test. In this research, the effect of different compaction in energy of 25 number of blows compared to 40 number of blows on the stress-strain behaviour of drained triaxial test has been done and findings of the data are to be compared with direct shear test. Results reveal that there is an increase in soil unit weight by using different energy in compaction with an increase of 5% from 1790 kg/m3 to 1880 kg/m3 for 25 and 40 number of blows respectively. However, the stress-strain behaviour of the specimens shows differently when compared between consolidated drained triaxial and direct shear test. The shear strength for direct shear-stress is at higher value compared to drained triaxial test. For drained triaxial test, results reveal that the effective friction angles are increase only about 1% from 37° to 38°. This is due to the soil particles rearranging itself with the different applied pressures thus eliminating the effects of different energy on the shear strength of the specimens. However, for direct shear test, the shear strength increases drastically from 29° to 32°. The increase of the shear strength is more likely influence by the soil particle arrangement due to the impact of the energy of the no of blows to the desired specimen.
20
Tarpey, R. A., M. F. Jurgensen, B. J. Palik, and R. K. Kolka. "The long-term effects of silvicultural thinning and partial cutting on soil compaction in red pine (Pinus resinosa Ait.) and northern hardwood stands in the northern Great Lakes Region of the United States." Canadian Journal of Soil Science 88, no. 5 (November 1, 2008): 849–57. http://dx.doi.org/10.4141/cjss08001.
Повний текст джерелаАнотація:
Periodic silvicultural thinnings (23.0, 27.6, 32.1 m2 ha-1 residual basal area) in a red pine stand growing on a sandy soil in north-central Minnesota over a 57-yr period increased soil compaction as the intensity of the thinning treatment increased. Of the three different methods used to measure soil compaction (bulk density, penetration resistance, and saturated hydraulic conductivity), saturated hydraulic conductivity was the most sensitive, decreasing by 60% in the 23.0 m2 ha-1 basal area thinning treatment, as compared with the uncut control. Soil bulk density measurements were more variable, but generally increased with increased thinning intensity. Few differences in soil penetration resistance were found among the three thinning treatments. In contrast, no evidence of soil compaction was detected in a northern hardwoods stand growing on a rocky loam soil in north-central Wisconsin that had three thinning treatments (13.8, 17.2, 20.6 m2 ha-1 residual basal area), a two- stage shelterwood harvest, and a 20-cm-diameter limit cut over a 50-yr period. With the increased demand for forest products, fuel reduction operations in high fire-risk stands, and biomass removal for energy production, more information is needed on the impact of multiple stand entries on soil compaction, and if compaction occurs, whether it will affect long-term soil productivity. Key words: Soil physical properties, bulk density, soil penetration resistance, hydraulic conductivity
21
Umer, R., H. Alhussein, J. Zhou, and WJ Cantwell. "The mechanical properties of 3D woven composites." Journal of Composite Materials 51, no. 12 (November 30, 2016): 1703–16. http://dx.doi.org/10.1177/0021998316681187.
Повний текст джерелаАнотація:
In this work, three types of 3D woven fabric (orthogonal, angle interlock, and layer-to-layer) were used to study the effect of weaving architecture on processing and mechanical properties. In order to characterize the fabrics for liquid composite molding processes, the compaction and permeability characteristics of the reinforcements were measured as function of fiber volume fraction. High compaction pressures were required to achieve a target fiber volume fraction of 0.65, due to presence of through-thickness binder yarns that restricts fiber nesting. In-plane permeability experiments were completed and flow front patterns were obtained to understand the anisotropy in the laminates. The resin transfer molding process was then used to manufacture panels that were then tested under quasi-static flexure and low-velocity impact conditions. It was found that the flexural strength and modulus were higher along the weft direction, where high in-plane permeability of the reinforcement was observed, due to fiber alignment. Impact tests on composite plates based on the three types of fabric indicated that the orthogonal system offered a slightly higher perforation resistance and lower levels of damage at any given energy.
22
Shaheb, Md Rayhan, Ramarao Venkatesh, and Scott A. Shearer. "A Review on the Effect of Soil Compaction and its Management for Sustainable Crop Production." Journal of Biosystems Engineering 46, no. 4 (November 24, 2021): 417–39. http://dx.doi.org/10.1007/s42853-021-00117-7.
Повний текст джерелаАнотація:
Abstract Purpose Sustainable crop production could contribute to feed and fuel for the ever-increasing global population. The use of heavy agricultural machinery has improved the efficiency of farming operations and increased global food production since the 1950s. But their negative impact on soil includes changing soil structure resulting in deteriorating soil productivity and environmental quality is being noticed for several decades. The purpose of this review is to summarize and help to better understand the effect of heavy machinery, tire inflation pressure, and field traffic on soil properties and crop development, yield, and economics of different farming systems published in the last 20 years. Methods Search engines such as Google Scholar, Scopus, Science Direct, Springer Link, Wiley Online, Taylor & Francis Online, Academia, and Research Gate platforms were used to collect and review the articles. This review includes indexed journals, conference and symposium proceedings, reports, academic presentations, and thesis/dissertations. Results Soil compaction increases bulk density and soil strength and reduces soil porosity and soil hydraulic properties. Stunted plant root growth due to compaction of soil affects crop growth and development, and yield. Soil compaction resulting from heavy machinery traffic caused a significant crop yield reduction of as much as 50% or even more, depending upon the magnitude and the severity of compaction of the soil. Conclusions High gross weight vehicles/machinery traffic damages soil structure and soil environment that are critical for sustainable crop production. The use of heavy machinery such as subsoiling for removing soil compaction results in more fuel use, increased use of energy, cost, and sometimes risks of re-compaction, further deteriorating soil conditions and causing additional adverse environmental consequences. The economics of different farming systems affected by soil compaction, potential soil compaction management strategies, and future research needs have also been discussed.
23
Halimi, Behrouz, Hamidreza Saba, Saeid Jafari MehrAbadi, and Saeid Saeidi Jam. "Laboratory study and measurement of stiffness and compaction of unsaturated clay soil by using the innovative rebound hammer." Nexo Revista Científica 34, no. 02 (June 7, 2021): 710–32. http://dx.doi.org/10.5377/nexo.v34i02.11557.
Повний текст джерелаАнотація:
Defining soil behavioral parameters, which eventually results in predicting every short-term and long-term soil behavior, has continually been one of the interests of soil mechanics and has been of exceptional value. To this end, in this study, a novel method has been reviewed to determine the compressive behavior of fine-grained soils in the laboratory and the field, without sampling by the patented electronic device. In the lab, homogeneous materials of the intended soil underwent the compaction test, mechanical and physical tests, direct shear test, and impacts of the innovative rebound hammer in the horizontal and vertical directions in the test-box. The impact shear waves produce resistance and voltage output by force and dislocation sensors with high-sensitivity proportional to the pressure based on the soil surface stiffness. The obtained voltages are then converted to digital by an analog-to-digital converter and a microcontroller. Next, a number is shown on display by the "CodeVision" program. Then, by solving a quasi-dynamic equation (Viscoelastic spring-damper model) by MATLAB software and with the aid of laboratory-field results and correlation equations, a fitting connection between all effective mechanical soil parameters has been estimated to an acceptable extent. The effective mechanical parameters of the soil include the compaction percentage, specific gravity, and frequency of the system in the damped and non-damped states, the energy imposed on the soil, and the plastic stage strain in the range of less than 15% humidity. The results determine that increased hammering numbers are directly related to increased soil compaction and stiffness. In more detail, the reading of hammer numbers less than 2 corresponds to compaction of less than 75%, while the reading of hammer numbers greater than 3 in the vertical and 2.94 in the horizontal directions on clay surfaces designates compaction of 90%.
24
Wang, Li, Ruizhao Yang, Zhipeng Sun, Lingda Wang, Jialiang Guo, and Ming Chen. "Overpressure: Origin, Prediction, and Its Impact in the Xihu Sag, Eastern China Sea." Energies 15, no. 7 (March 30, 2022): 2519. http://dx.doi.org/10.3390/en15072519.
Повний текст джерелаАнотація:
The complex relationship between deep overpressure, abnormal porosity, and hydrocarbon generation in the Pinghu Formation is interesting and challenging for hydrocarbon exploration and development in the East China Sea Shelf Basin. It shows three-stage pore pressure evolution based on the characteristics of logs in the west slope of the Xihu Sag. Disequilibrium compaction was identified as the dominant overpressure mechanism in stage II (1.0 < PC < 1.6). The fluid expansion was identified as the predominant mechanism of overpressure generation in stage III (PC > 1.6), and tectonic compression occurs in Well B. Pore pressure was predicated by the Fillippone method based on the combination of raw velocity spectra and high-resolution velocity parameters obtained by seismic inversion. The overpressure at the bottom of the Pinghu Formation is mainly distributed in the F2 and F3 fault blocks. The deep gas reservoir of the Pinghu Formation is controlled by both lithology and pressure. The overpressure distribution area is consistent with the center of hydrocarbon generation. The overpressure distribution illustrated that overpressure was positively correlated with the porosity and permeability of the reservoir. The first porosity and permeability inversion zone of the Pinghu Formation formed because the overpressure caused by under-compaction offsets the pressure of some overlying strata and slows down diagenesis. Due to a large amount of hydrocarbon generation in source rocks, the acidic fluid with high temperature promoted the development of secondary pores, resulting in the second pore permeability inversion zone of the Pinghu Formation. The index of porosity preserving (IPP) is proposed here to quantitatively describe the relationship between overpressure and porosity. The index of porosity preserving in the second stage is 1.16%/10 MPa, and in the third stage is 1.75%/10 MPa. The results can be used to guide the exploration of the deep-basin gas reservoir of the Xihu Sag in the Eastern China Sea Basin.
25
Rominiyi, Azeez Lawan, Mxolisi Brendon Shongwe, Enoch Nifise Ogunmuyiwa, Samson Olaitan Jeje, Smith Salifu, Olanrewaju Seun Adesina, and Peter Apata Olubambi. "Dry Sliding Wear and High-Velocity Impact Behaviour of Spark Plasma Sintered Ti-Ni Binary Alloys." International Journal of Engineering Research in Africa 57 (November 9, 2021): 1–18. http://dx.doi.org/10.4028/www.scientific.net/jera.57.1.
Повний текст джерелаАнотація:
This work investigated the dry sliding wear behaviour of spark plasma sintered (SPSed) Ti-Ni binary alloys produced at varying nickel content with alloy steel ball as the counterface material, at room temperature under varied applied normal loads. Finite element modeling was used to investigate the high-velocity impact response of the sintered alloys due to the dimensional constraint associated with SPSed samples. Microstructural analysis results revealed the presence of intermetallic phases of Ti-Ni with increasing nickel content. The best wear resistance ranging from 0.25 x 10-3 mm3/Nm to 0.22 x 10-3 mm3/Nm across all applied loads was obtained in Ti-6Ni alloy. This was attributed to the compaction of the protective triboxide and carbide layers on the surface of the sample. Oxidative and wear by adhesion were observed at low applied normal load while at high loads the prevalent wear mechanism was abrasive with reduced influence of oxidative and adhesive wear. Finite element analysis results also showed that Ti-6Ni alloy possessed the optimum combination of absorbed energy and ductility to reduce the possibility of brittle failure under impact loading. Keywords: Ti-Ni binary alloys; Spark plasma sintering; Dry sliding wear; High-velocity impact; Finite element analysis.
26
de Sales Pereira Mendonça, Claudiney, Vander Alkmin dos Santos Ribeiro, Mateus Morais Junqueira, Daniela Sachs, Leonardo Albergaria Oliveira, Mírian de Lourdes Noronha Motta Melo, and Gilbert Silva. "Recycling Chips of Stainless Steel by High Energy Ball Milling." Materials Science Forum 930 (September 2018): 454–59. http://dx.doi.org/10.4028/www.scientific.net/msf.930.454.
Повний текст джерелаАнотація:
Stainless steel components produced by powder metallurgy constitute an important and growing segment of the industry. The high energy ball milling process can be an alternative for the recycling of the stainless steel chips. A major advantage of stainless steel is its ability to be recyclable. The reuse of recyclable materials has as main objectives to minimize the environmental impacts and to rationalize the use of the energy chains. This work aims at the production of stainless steel, starting from machining chips pure, and with the addition of vanadium carbides by high energy planetary milling with ball to powder weight ratio 20:1, and mill speed of 350 rpm milled in argon atmosphere for 50h. The compaction of stainless steel samples with vanadium carbide was made in a cylindrical matrix at a pressure of 700 Mpa. The sintering process was performed in a vacuum atmosphere furnace at a temperature of 1200 ° C for 1h. Through the milling process with the addition of carbide it was possible to produce stainless steel powder with a mean particle size of 49 μm. By X-ray diffraction was observed the appearance of the ferritic, austenitic phase and the martensitic phase induced by deformation phase that remained even after the sintering. The density of the sintered material is around 77% of the melt, and the obtained porosity was low.
27
Mousa, Elsayed, Mania Kazemi, Mikael Larsson, Gert Karlsson, and Erik Persson. "Potential for Developing Biocarbon Briquettes for Foundry Industry." Applied Sciences 9, no. 24 (December 4, 2019): 5288. http://dx.doi.org/10.3390/app9245288.
Повний текст джерелаАнотація:
The foundry industry is currently facing challenges to reduce the environmental impacts from application of fossil fuels. Replacing foundry coke with alternative renewable carbon sources can lead to significant decrease in fossil fuel consumption and fossil CO2 emission. The low bulk density, low energy density, low mechanical strength and the high reactivity of biocarbon materials are the main factors limiting their efficient implementation in a cupola furnace. The current study aimed at designing, optimizing and developing briquettes containing biocarbon, namely, biocarbon briquettes for an efficient use in cupola furnace. Laboratory hydraulic press with compaction pressure of about 160 MPa and stainless-steel moulds (Ø = 40 mm and 70 mm) were used for compaction. The density, heating value, energy density, mechanical strength and reactivity of biocarbon briquettes were measured and evaluated. The compressive strength and splitting tensile strength of biocarbon briquettes were measured by a compression device. The reactivity of biocarbon briquettes was measured under controlled conditions of temperature and gas atmosphere using the thermogravimetric analysis technique (TGA). Different types of binders were tested for the compaction of commercial charcoal fines with/without contribution of coke breeze. The effect of charcoal ratio, particle size, binder type, binder ratio, moisture content and compaction pressure on the quality of the biocarbon briquettes was investigated. Molasses with hydrated lime and cement were superior in enhancing the biocarbon briquettes strength and energy density among other tested binders and additives. The briquettes’ strength decreased as the biocarbon content increased. The optimum recipes consisted of 62% charcoal fines, 20% molasses, 10% hydrated lime and 8% cement. Cement is necessary to develop the tensile strength and hot mechanical strength of the briquettes. The charcoal with high ash content showed higher strength of briquettes but lower heating value compared to that with low ash content. Dispersion of silica suspension on charcoal particles during the mixing process was able to reduce the reactivity of biochar in the developed biocarbon briquettes. The biocarbon briquettes density and strength were increased by increasing the compaction pressure. Commercial powder hydrated lime was more effective in enhancing the briquettes’ strength compared to slaked burnt lime. Upscaling of biocarbon briquettes (Ø = 70 mm) and testing of hot mechanical strength under load indicated development of cracks which significantly reduced the strength of briquettes. Further development of biocarbon briquettes is needed to fulfil the requirements of a cupola furnace.
28
Zanotti, C., G. Riva, P. Giuliani, G. Daminelli, and A. Reggiori. "Shock Compression of Powders by Two-Stage Gasdynamic Gun." Advances in Science and Technology 45 (October 2006): 917–22. http://dx.doi.org/10.4028/www.scientific.net/ast.45.917.
Повний текст джерелаАнотація:
Powder consolidation using a shock compression apparatus is a potential method for the processing of bulk materials. Two-stage gasdynamic guns take advantage of light gases properties to accelerate projectiles to hypervelocity. The prototype developed at the CNR-IENI labs was modified in order to densify powders in very short times (1-100 μs). Powder compaction can be achieved either by the generation of a pressure pulse (10-30 104 bar) or by direct impact on the powder sample of a high speed projectile (0.5 - 2 Km/s). A numerical code, to simulate the gasdynamic gun behavior, has been written and, depending on the densification method (pressure pulse or impact) can be used to calculate the pressure and temperature histories in the densification stage or the pellet velocity, momentum and kinetic energy just before the impact. Preliminary experimental tests indicate the capability of this apparatus to densify different kind of precompacted powders.
29
Saleh, Afrah Hassan. "Depositional Environment and Diagenesis processes impact on the carbonate rock quality: a case study, southeastern of Iraq." Iraqi Journal of Science 60, no. 5 (May 26, 2019): 1104–14. http://dx.doi.org/10.24996/ijs.2019.60.5.19.
Повний текст джерелаАнотація:
Deposition environment and diagenesis processes are very important factors which affect and control the reservoir properties. The carbonate Mishrif Formation has been selected as a carbonate reservoir in selected wells from southeastern Iraq to understand the influence of the Deposition environment and diagenesis processes on the carbonate reservoir. A core examination of thin sections, shows that Mishrif Formation comprises of six depositional environments, these are: deep marine, lagoon, rudist biostrome, back shoal, and shallow open marine. These environments have effect by many diagenetic processes, including dolomitization, dissolution, micritization, cementation, recrystallization and Stylolite, some of these processes have improved the reservoir properties of the Mishrif reservoir, these are: dissolution, dolomitization and the stylolization. The others diagenetic processes have negative influence on the Petrophysical properties, such as cementation, compaction, and recrystallization processes, which damage the porosity and decrease the pore size. The reservoir properties are controlled by deposition environment, where lagoon environment is mostly compact with low porosity, shoal environment reflects a high energy and grain-supported environment and has good reservoir potential, deep-marine environments consist of mudstone to wackestone, which represents low energy level with low porosity and represents the non-reservoir environment.
30
Fleming, Paul, Charlie Watts, Jon Gunn, and Steph Forrester. "Hardness Safety Testing of Artificial Turf." Proceedings 49, no. 1 (June 15, 2020): 130. http://dx.doi.org/10.3390/proceedings2020049130.
Повний текст джерелаАнотація:
This paper compares four sport surface hardness impact test devices, for use on artificial turf (AT) surfaces to control safety. Sports governing bodies require sport surfaces to be assessed with the “Advanced Artificial Athlete” (AAA) mechanical test. The AAA data presented here demonstrate that this high energy test causes compaction of the particulate rubber infill during testing, such that the derived “field test value” is less relevant to the initial state of the surface and arguably also to player comfort. This paper reports on alternative impact test methods and their correlation to the AAA, including a novel comparison to the more portable Fieldtester. The potential use of a lightweight 0.5 kg Clegg Hammer for assessing the change in state of the infill and monitoring the effectiveness of field maintenance is also reported. These results expand our understanding of factors influencing surface hardness and safety, with useful implications for practitioners.
31
Diener, Alexander, Julian Kristoffer Mayer, Yue Zhang, and Arno Kwade. "Analysing the Effects of High-Intensive Dry Mixing on the Calendering Process and Cell Performance of NMC622 Based Cathodes." ECS Meeting Abstracts MA2022-01, no. 2 (July 7, 2022): 300. http://dx.doi.org/10.1149/ma2022-012300mtgabs.
Повний текст джерелаАнотація:
A reliable design of production processes for the manufacturing of lithium-ion battery electrodes requires a deep understanding of the interdependency of processes, the resulting electrode microstructure and the influence on the cell performance indicators, like energy density, cycle life and aging. In the present study, the focus lays on the calendering process during which the electrode coating is compacted with the aim of adjusting uniform electrode properties such as mechanical, electrical and electrochemical behavior. Compaction of the electrode coating affects the pore structure and therefore has a crucial influence on the electrical and electrochemical behavior of the cell. Consequently, process and machine parameters have to be adapted in order to generate electrode structures optimized for a desired application. To meet this target, an in-depth understanding of how the calendering process affects the electrode structure beyond the simple reduction of porosity and further how the calendering process itself is affected by the preceding process steps like dry or wet mixing is mandatory. Thus, the focus of the presented work is to investigate the interdependency between the dry mixing process step and the subsequent calendering process by correlating powder properties adjusted via the dry mixing with the machine behavior during the calendering as well as the resulting coating density. The impact of the calendering process on the electrode microstructure and its correlation with electrode properties by developing process-product-property functions, regarding the above mentioned criteria, is an additional focus of the presented study. Therefore, powder mixtures of NMC622 with carbon black were created under varying the dry mixing intensity and thus adjusting the carbon black agglomerate size. The created powder mixtures were comprehensively characterized, e.g. particle size distribution and powder conductivity, and then used to build up electrodes which afterwards were compacted to different coating densities. The correlation between the powder properties and the calendering behavior shows a higher compaction resistance with decreasing carbon black agglomerate size. Whereas reducing the carbon black agglomerate size leads to lower electrical resistivity and therefore strongly impacts the C-rate capability.
32
Zhao, Hairui, Yao Shi, Guang Pan, and Qiaogao Huang. "Study on Impact Load and Head Cap Load Reduction Performance of Vehicle Entering Water at High Speed." Journal of Marine Science and Engineering 10, no. 12 (December 5, 2022): 1905. http://dx.doi.org/10.3390/jmse10121905.
Повний текст джерелаАнотація:
Aiming at the problem of high-speed entry of vehicles with a diameter of 200 mm, a numerical model of high-speed entry of vehicles is established based on the arbitrary Lagrange–Euler (ALE) algorithm, and the numerical simulation of high-speed entry of flat-nosed and round-nosed vehicles is carried out. On this basis, the experimental research on the entry of vehicle with buffer caps is carried out. The following conclusions are obtained through simulation. The peak value of the axial load of the vehicle raises with the increase of the inlet velocity and angle, while the stable value only raises with the increase of the inlet velocity. The impact load on the round-nosed vehicle is obviously smaller than that on the flat-nosed vehicle when the water entry angle is greater than 80°. The peak value of axial load can be reduced by 22% when entering water vertically at 100 m/s. The following conclusions are obtained through experiments. The buffer head cap has a significant load reduction effect. It shows compaction, cracks and breakage under the impact of water. These processes can absorb part of the impact energy, reduce the peak value of axial load and increase the pulse width. The load reduction rate grows from 4.7% to 18.5% when the length of the buffer head cap is increased from 200 mm to 300 mm while the water inlet speed is the same. The damage level of the head cap increases sharply, and the load reduction rate raises when the water entry speed is increased while the length of the buffer head cap is the same.
33
Planes, María Belén, Emmanuel N. Millán, Herbert M. Urbassek, and Eduardo M. Bringa. "Collisions between micro-sized aggregates: role of porosity, mass ratio, and impact velocity." Monthly Notices of the Royal Astronomical Society 503, no. 2 (March 5, 2021): 1717–33. http://dx.doi.org/10.1093/mnras/stab610.
Повний текст джерелаАнотація:
ABSTRACT Dust aggregate collisions usually occur between mass-asymmetric collision partners. Granular-mechanics simulations are used to study the influence of filling factor, φ, and impact velocity in collisions of spherical granular aggregates with different values of their mass ratio, but the same filling factor. Three possible outcomes are observed: (i) sticking, which might include penetration of the smaller aggregate into the larger aggregate; (ii) fragmentation of the largest aggregate into two large fragments, particularly due to the so-called piston effect for low filling factors; and (iii) total destruction of the aggregates. Most of the impact energy is spent by friction, with some fraction leading to compaction of the porous material. The erosion efficiency varies significantly with impact velocity, mass ratio, and porosity, but the accretion efficiency does not show such strong variations. For highly asymmetric collisions with high impact velocities (≃100 m s−1), grain accretion (growth) can occur for a ‘window’ in the filling factor (0.20 < φ < 0.35). This window becomes wider as the impact velocity decreases. As the mass ratio of the aggregates decreases, the impact velocities that enable growth can also decrease. The mass distribution of the fragments follows a power-law distribution that is almost independent of the mass ratio, filling factor, and velocity.
34
Grigorev, Igor, Olga Kunickaya, Albert Burgonutdinov, Evgeniy Tikhonov, Valentin Makuev, Sergey Egipko, Edward Hertz, and Maksim Zorin. "Modeling the effect of wheeled tractors and skidded timber bunches on forest soil compaction." Journal of Applied Engineering Science 19, no. 2 (2021): 439–47. http://dx.doi.org/10.5937/jaes0-28528.
Повний текст джерелаАнотація:
An increasing demand for forest products incites a large number of log transportation operations, which may lead to negative consequences for the soil and the ecosystem as a whole. This paper is focused on establishing a mathematical model to estimate the soil deformation and compaction processes under tires of wheeled forest machines and individual components of the skidding system such as forwarder, limbs, butts, and tops of tree-lengths in high latitudes, permafrost soil and forests. The method applied is based on simulating the impact processes of elastic tires and the skidding system on the soil through a mathematical device for the measurement of the compaction parameters for different types of soil and the size of the shelterbelt. The effectiveness of the proposed models was evaluated according to experimental results. The influence of the rheological (elastic, viscous, and plastic) properties of soil were studied. The elasticity of tires and the running speed of forest machines can help to control the performance of forest machines. This can be done by reducing the pressure exerted on the soil and increasing the number of skidder passes 1.5-2-fold. Comparative analysis showed that the calculated data differ from the experimental ones by no more than 10%. The obtained results and the developed model will allow for a qualitative and quantitative assessment of technological impact on the soil during the projecting maps for logging operations.
35
ZHAO, GUIPING, SANG-KYO LEE, and CHONGDU CHO. "EFFECT OF COMPRESSIVE RESIDUAL STRESS INDUCED DURING FABRICATING PROCESS IN THE CORE OF CLAMPED SANDWICH PLATE UNDER SHOCK LOADING." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1195–200. http://dx.doi.org/10.1142/s0217979208046530.
Повний текст джерелаАнотація:
Sandwich panels can be manufactured in many ways like lamination press, closed mold fabrication, and vacuum bag compaction. During manufacturing, the core and the sheets are attached under certain applied pressure and temperature, associated with a deformation and stress remaining in the sandwich core. This study presents an evaluation of the compressive residual stress effect of the core which occurs during the localized shock loading at the mid-span of a clamped sandwich plate. We simulate such a square lattice core sandwich plate by commercial finite element code, ABAQUS/Explicit. We apply uniform distributed loading on upper face sheet and temperature difference occurred during the manufacturing process is taken here before the impact simulation step. These loadings induce certain amount of residual stresses in core structure of sandwich panel. The computational result from non-residual stress case is verified by comparing with the results of published experimental data on similar investigation. In addition, the effect of existing residual stress at core is analyzed. We also compare the dynamic responses of two clamped sandwich plates with and without pre-stressed core. And impact resistance of sandwich panel is explained in the view of energy capacity. Results show that the shock loading behavior of sandwich panel depends on its manufacturing process and panels with compressive residual stresses have less deformation and high impact energy absorption characteristics.
36
van Damme, Myron. "A process-based method for predicting lateral erosion rates." Natural Hazards 107, no. 1 (February 12, 2021): 375–94. http://dx.doi.org/10.1007/s11069-021-04587-y.
Повний текст джерелаАнотація:
AbstractAn accurate means of predicting erosion rates is essential to improve the predictive capability of breach models. During breach growth, erosion rates are often determined with empirical equations. The predictive capability of empirical equations is governed by the range for which they have been validated and the accuracy with which empirical coefficients can be established. Most empirical equations thereby do not account for the impact of material texture, moisture content, and compaction energy on the erosion rates. The method presented in this paper acknowledges the impact of these parameters by accounting for the process of dilation during erosion. The paper shows how, given high surface shear stresses, the erosion rate can be quantified by applying the principles of soil mechanics. Key is thereby to identify that stress balance situation for which the dilatency induced inflow gives a maximum averaged shear resistance. The effectiveness of the model in predicting erosion rates is indicated by means of three validation test cases. A sensitivity analysis of the method is also provided to show that the predictions lie within the range of inaccuracy of the input parameters.
37
Zumr, David, Danilo Vítor Mützenberg, Martin Neumann, Jakub Jeřábek, Tomáš Laburda, Petr Kavka, Lisbeth Lolk Johannsen, et al. "Experimental Setup for Splash Erosion Monitoring—Study of Silty Loam Splash Characteristics." Sustainability 12, no. 1 (December 24, 2019): 157. http://dx.doi.org/10.3390/su12010157.
Повний текст джерелаАнотація:
An experimental laboratory setup was developed and evaluated in order to investigate detachment of soil particles by raindrop splash impact. The soil under investigation was a silty loam Cambisol, which is typical for agricultural fields in Central Europe. The setup consisted of a rainfall simulator and soil samples packed into splash cups (a plastic cylinder with a surface area of 78.5 cm2) positioned in the center of sediment collectors with an outer diameter of 45 cm. A laboratory rainfall simulator was used to simulate rainfall with a prescribed intensity and kinetic energy. Photographs of the soil’s surface before and after the experiments were taken to create digital models of relief and to calculate changes in surface roughness and the rate of soil compaction. The corresponding amount of splashed soil ranged between 10 and 1500 g m−2 h−1. We observed a linear relationship between the rainfall kinetic energy and the amount of the detached soil particles. The threshold kinetic energy necessary to initiate the detachment process was 354 J m−2 h−1. No significant relationship between rainfall kinetic energy and splashed sediment particle-size distribution was observed. The splash erosion process exhibited high variability within each repetition, suggesting a sensitivity of the process to the actual soil surface microtopography.
38
Wang, Jian, Lu Zhou, Jin Liu, Erting Li, and Benzhong Xian. "Genesis of diagenetic zeolites and their impact on reservoir formation in the Middle Permian Lower-Wuerhe Formation of the Mahu Sag, Junggar Basin, Northwest China." Energy Exploration & Exploitation 38, no. 6 (July 13, 2020): 2541–57. http://dx.doi.org/10.1177/0144598720937476.
Повний текст джерелаАнотація:
Zeolites are important diagenetic minerals in petroleum reservoirs and have complex impacts on reservoir quality. To highlight this critical and challenging issue, we conduct a case study in the Middle Permian Lower-Wuerhe Formation in the Mahu Sag, Junggar Basin, China. Formation mechanism of zeolites and their impacts on the reservoir quality. Our results show that there are five types of zeolite minerals (i.e. laumontite, heulandite, analcime, stilbite, and clinoptilolite) in the Lower-Wuerhe Formation reservoir, with laumontite and heulandite being the main types. Petrographic and geochemical data suggested that laumontites developed in the Lower-Wuerhe Formation were mainly precipitated from pore water, whereas heulandites were formed associated with alteration of volcanic materials. In addition, the distribution of different type of zeolite minerals is generally controlled by sedimentary facies. The heulandite–laumontite zone developed mainly in the front of fan-delta plain, and the laumontite zone developed mainly in fan-delta front. The distal part of fan-delta front is dominated by albite. The zeolite mineral assemblages are generally controlled by geochemical composition of volcanic lithic fragments. The high content of intermediate-basic volcanic lithic fragments in the eastern Mahu Slope sediments is responsible for authigenic minerals such as heulandite, chlorite, and laumontite. However, the content of intermediate-basic volcanic lithic fragments in the western Mahu Slope sediments is low which results in the cement in this region is dominated by laumontite and mixed-layer illite/smectite. In general, conglomerates deposited in fan-delta front are favorable for the formation of early laumontite and late dissolution of laumontite due to resistance to compaction by coarse fraction and accumulation of acidic fluids in structural highs, which resulted in the formation of a high-quality reservoir. Our results have general implications for hydrocarbon exploration of the zeolite-bearing conglomerate reservoirs in non-marine petroliferous basins.
39
Wu, Wangqing, Changsheng He, Yuanbao Qiang, Huajian Peng, and Mingyong Zhou. "Polymer–Metal Interfacial Friction Characteristics under Ultrasonic Plasticizing Conditions: A United-Atom Molecular Dynamics Study." International Journal of Molecular Sciences 23, no. 5 (March 4, 2022): 2829. http://dx.doi.org/10.3390/ijms23052829.
Повний текст джерелаАнотація:
Understanding the properties of polymer–metal interfacial friction is critical for accurate prototype design and process control in polymer-based advanced manufacturing. The transient polymer–metal interfacial friction characteristics are investigated using united-atom molecular dynamics in this study, which is under the boundary conditions of single sliding friction (SSF) and reciprocating sliding friction (RSF). It reflects the polymer–metal interaction under the conditions of initial compaction and ultrasonic vibration, so that the heat generation mechanism of ultrasonic plasticization microinjection molding (UPMIM) is explored. The contact mechanics, polymer segment rearrangement, and frictional energy transfer features of polymer–metal interface friction are investigated. The results reveal that, in both SSF and RSF modes, the sliding rate has a considerable impact on the dynamic response of the interfacial friction force, where the amplitude has a response time of about 0.6 ns to the friction. The high frequency movement of the polymer segment caused by dynamic interfacial friction may result in the formation of a new coupled interface. Frictional energy transfer is mainly characterized by dihedral and kinetic energy transitions in polymer chains. Our findings also show that the ultrasonic amplitude has a greater impact on polymer–metal interfacial friction heating than the frequency, as much as it does under ultrasonic plasticizing circumstances on the homogeneous polymer–polymer interface. Even if there are differences in thermophysical properties at the heterointerface, transient heating will still cause heat accumulation at the interface with a temperature difference of around 35 K.
40
Joshi, Shailendra, Gaurav Gupta, Mohit Sharma, Amit Telang, and Taru Mahra. "Synthesis and Characterization of Stainless Steel Foam Via Powder Metallurgy Taking Acicular Urea As Space Holder." Material Science Research India 12, no. 1 (June 24, 2015): 43–49. http://dx.doi.org/10.13005/msri/120108.
Повний текст джерелаАнотація:
Stainless steel foams are produced via powder metallurgy process taking acicular urea as space holder contributing porosity with 40-70 volume %. The resulting changes in microstructure of compact after each operation comprising cold compaction, pre-heating and sintering are discussed along with causes with the help of SEM micrograph. The processed foam samples using 40 % urea by volume are quite regular and acicular in shape but with increase in porosity regularity starts diminishing. It is observed that the foam samples with 40 % porosity doesn’t show any plateau stress as in aluminum foams but those with 50 % porosity (approximately 80 MPa maximum plateau stress) and 60 % porosity (approx.45MPa) shows plateau region in true stress-strain diagram during compression test due before final densification process. It is observed that with increasing porosity plateau stress decreases, since lesser force is required to densify the foam. Therefore the stainless steel foams with low porosity can be used in light weight high strength applications e.g. structures whereas with high porosity have impact energy absorbing applications e.g. damping elements in buildings or vehicles, etc.
41
Gudkov, Viktor, Pavel Sokol, Aleksandr Bozhko, Tatyana Novikova, and Siarhei Rabko. "BIAXIAL ARTICULATED TIMBER VEHICLES IN THE CONDITIONS OF A FELLING: ASSESSMENT OF APPLICABILITY." Forestry Engineering Journal 12, no. 4 (January 1, 2023): 88–95. http://dx.doi.org/10.34220/issn.2222-7962/2022.4/6.
Повний текст джерелаАнотація:
The study can provide decision-making support to loggers and participants in forest relations who are obliged to carry out reforestation activities to assess the factors that change the effectiveness of forestry and logging operations. The balance of production and environmental effects from the use of forest transport machines in the development of forestry is an important step in effective quality management of forest landscape restoration. The degree of compaction of the forest soil from the impact of propellers directly affects both the fuel consumption of the power plant of the forest transport machine and the ability of forest seeds of the main breed to germinate. The primary transportation of trees and their parts (whips, balances, assortments, waste residues and other waste of logging production) occupies an increasing volume in the energy balance of the timber transport machine. It is necessary to solve complex problems of choosing energy-efficient and maneuverable biaxial articulated timber transport vehicles in comparison with machines with a continuous frame for performing transport work in the conditions of a cutting area. In order to maximize the requirements for the efficient operation of machines in difficult cutting conditions, it is necessary to ensure, along with high operational properties (traction, cross-country ability, maneuverability, smooth running), a high level of technical and economic indicators. The assessment of the applicability of existing structures of forest transport vehicles was carried out by statistical methods of Ward and intergroup relations according to the criteria of soil compaction, patency, maneuvering, power circulation, traction losses, balance of weight distribution and purpose. When planning future research, it is necessary to answer a number of questions: which criterion should be used as a universal one for unambiguous selection of the type of forest transport vehicle? Is it possible to estimate the geomorphology of the future cutting area in advance with the use of unmanned aircraft systems and predict the effective trajectories of movement of articulated timber vehicles?
42
Shi, Jian, Yanbo Lin, Aibin Zhao, Xinxing Wang, Kaisheng An, Xiangyun Zhong, Kelai Hu, Yushuang Zhu, and Linyu Liu. "Diagenetic features and porosity dense evolution of Chang 8 tight sandstone reservoir in Hujianshan area, Ordos Basin." Journal of Petroleum Exploration and Production Technology 11, no. 3 (February 17, 2021): 1037–51. http://dx.doi.org/10.1007/s13202-021-01092-7.
Повний текст джерелаАнотація:
AbstractDiagenesis is the main reason for tight reservoir lithology, complex pore-throat structure, strong heterogeneity, and variable occurrence and distribution characteristics of fluid in the pore-throat, which directly restricts the Chang 8 oil layer group in the Ordos Basin. Exploration and development. Based on the analysis of a large number of cores and thin slices, through the application of scanning electron microscopy, high-pressure mercury intrusion and other experimental testing methods, the diagenesis characteristics of the Chang 8 tight reservoir in the Hujianshan area of the Ordos Basin and the mechanism and process of tight porosity evolution are analyzed in depth. The relationship between different diagenetic facies belts, pore structures and their impact on reservoir quality is further explored. The results show that the Chang 8 reservoir in the Hujianshan area is in the mid-diagenetic stage A, which mainly experienced compaction-pressure dissolution, cementation, dissolution and other diagenesis. The compaction caused the loss of a large number of primary pores in the sandstone, which is the most important factor for the densification of the Chang 8 reservoir in the study area, followed by cementation of carbonate and clay minerals. The chlorite clay film formed in the early diagenesis retained the primary particles. The inter-pores maintain good reservoir physical properties, and are affected by the acidic diagenetic environment. The unstable feldspar minerals dissolve. The dissolution pores produced effectively improve the connectivity and permeability of the pores. The compaction reduces the porosity on average by 19.37% and the loss rate reaches 51.86%. The cementation reduces the porosity on average by 11.97% and the loss rate reaches 32.66%. The dissolution increases the porosity by 3.26% on average. In the process of pore evolution, the compaction of the early diagenetic stage A and the authigenic clay minerals and carbonate cementation in the middle diagenetic stage are the main reasons for the substantial decrease in porosity. The early diagenetic stage B is due to its short duration. Less porosity is lost. The secondary pores generated in the early diagenetic stage A are basically filled with microcrystalline calcite, while the organic acid dissolution in the middle diagenetic stage is limited. According to different diagenetic minerals and pore evolution characteristics, combined with logging response characteristics, the whole area is divided into four diagenetic facies. Among them, the residual chlorite-membrane intergranular-pore facies and the feldspar dissolution facies of chlorite film are the most favorable diagenetic facies. The findings of this study can help for better understanding of the diagenetic characteristics and quantitative evolution of pores, reveal the diagenetic-pore evolution rules of Chang 8 sandstone reservoirs in the study area, and provide a basis for reservoir evaluation and prediction in the study area.
43
Mittal, Abhinav, Chandra S. Rai, and Carl H. Sondergeld. "Proppant-Conductivity Testing Under Simulated Reservoir Conditions: Impact of Crushing, Embedment, and Diagenesis on Long-Term Production in Shales." SPE Journal 23, no. 04 (June 18, 2018): 1304–15. http://dx.doi.org/10.2118/191124-pa.
Повний текст джерелаАнотація:
Summary Hydraulic fractures act as conduits connecting a wellbore to nanodarcy-permeability unconventional reservoirs. Proppants are responsible for enhancing the fracture conductivity, and they help in maintaining high production rates. This study is focused on the measurement of long-term conductivity of proppant packs at simulated reservoir-temperature and pressure conditions. Various conductivity-impairment mechanisms such as proppant crushing, fines migration, embedment, and diagenesis are investigated. Testing was performed with a conductivity cell that allows simultaneous measurement of fracture compaction and permeability. The proppant-pack performance during compression between metal and shale platens was compared. The proppant-filled fracture (concentration of 0.75–3 lbm/ft2) is subjected to axial load (5,000 psi) to simulate closure stress. Brine (3% NaCl + 0.5% KCl) is flowed through the pack at a constant rate (3 cm3/min) at 250°F during an extended duration of time (10–60 days). In this study, Ottawa sand proppant was used between platen facies fabricated from Vaca Muerta and Eagle Ford shales. Testing between metal platens indicated that the reduction in permeability with 20/40-mesh Ottawa sand (≈30% during 12 days) was less than that of 60/100-mesh Ottawa sand, which suffered a 99% reduction in only 4 days. Measurements with 20/40-mesh Ottawa sand between shale platens were conducted at 1.5 lbm/ft2. During a duration of 10 days, the Eagle Ford platens proppant pack exhibits a greater reduction in permeability, in comparison with Vaca Muerta platens. The normalized compaction for Eagle Ford shale platens is 20% more than Vaca Muerta platens because of greater proppant embedment. Particle-size analysis and scanning-electron-microscopy (SEM) images verify proppant crushing, fines migration, and embedment as dominant damage mechanisms. These factors are observed to depend on the testing of shales. The results suggest a substantial degradation of permeability during the initial 5 days of testing, after which the permeability appears to stabilize. Crushed proppant and dislodged shale-surface particles contribute to the fines generated; a greater concentration of fines is observed downstream. In a separate study between Vaca Muerta platens, under similar closure stress and temperature conditions at 2-lbm/ft2 proppant concentration, the permeability reduced by almost three orders of magnitude during a duration of 60 days. It was also observed that growth of diagenetic smectite is accelerated by making the fluid more basic (pH of 10).
44
Tuncev, Denis, Vitaliy Har'kov, and Maksim Kuznecov. "PROCESSING SUNFLOWER HUSK INTO HIGH STRENGTH COAL BRIQUETTES." Vestnik of Kazan State Agrarian University 14, no. 4 (April 12, 2020): 86–90. http://dx.doi.org/10.12737/2073-0462-2020-86-90.
Повний текст джерелаАнотація:
An urgent problem of the modern agro-industrial complex is the low efficiency of the use of secondary raw materials. On the basis of Rosstat data, in 2018 almost 13 million tons of sunflower seeds were collected in the country, which led to the accumulation of up to 1.8-3.2 million tons of husk, which is the ballast component of the technology for producing sunflower oil. Oil refineries continuously bear the costs of storage, safety, and the removal and disposal of such waste in landfills. Sunflower husk has a high calorific value, so thermochemical processing methods allow for the integrated processing of unclaimed raw materials of plant origin with moderate capital costs in energy and various chemical products. An experimental laboratory setup for conductive pyrolysis of plant materials has been developed to produce high-strength coal briquettes. The advantages of conductive heat feed pyrolysis reactors are simplicity of design and ease of maintenance. The results of a pilot study of the conductive pyrolysis process of sunflower husk showed that the obtained coal briquettes have a low ash content (6.2%), their maximum yield (29%) was achieved at a pressing pressure of 25 kg/cm2, and the maximum density of the samples was 1139 kg/cm3 (pressing pressure 153 kg/cm2). It was found that an increase in pressing pressure from 20 to 150 kg/cm2leads to an increase in the density of coal briquettes by 16%, and the maximum value of compression pressure is 566 kg/cm2. Also, at a compaction pressure of more than 50 kg/cm2, the impact resistance index during discharge reaches 100%. The developed technology provides a large mass yield of coal briquettes with high quality characteristics, which indicates the promise of utilizing sunflower husk by conductive pyrolysis in the fuel feed for the metallurgical industry.
45
Xu, Dong, Mingshi Gao, Yichao Zhao, Yongliang He, and Xin Yu. "Study on the Mechanical Properties of Coal Weakenedby Acidic and Alkaline Solutions." Advances in Civil Engineering 2020 (October 10, 2020): 1–15. http://dx.doi.org/10.1155/2020/8886380.
Повний текст джерелаАнотація:
A novel method for fracturing coal is presented in this paper. A chemical solution is injected into coal under high pressure, whereby the coal is fractured and subsequently weakened by chemical erosion over time to produce an anti-impact soft structure. In this study, the mechanical properties of coal under chemical erosion were investigated, and the fracturing design parameters were optimized. The uniaxial compression test and the split Hopkinson pressure bar (SHPB) test were used to determine the dynamic and static mechanical properties of coal after 20 days of immersion in different chemical solutions. After chemical solution erosion, the dynamic and static compressive strengths and elastic modulus of the coal decreased according to an exponential power law in the damage variable. The chemical treatment increased the duration of the pore compaction stage and decreased that of the elastic deformation stage, while decreasing the brittleness and increasing the ductility of coal. The acoustic emission (AE) curve of the immersed coal samples consisted of four stages corresponding to those of the stress-strain curve: pore compaction-closure, a slowly rising linear elastic regime, steady-state prepeak crack propagation, and unsteady crack propagation at the peak strain. The increase in the damage variable of the coal sample from chemical erosion led to a lower dissipated energy, a higher fractal dimension, and a more fragmented coal sample. The effect of the investigated chemical solutions on weakening the coal mechanical properties decreased in the following order: alkaline solution > acidic solution > NaCl solution > distilled water. The experimental results provide a reference for weakening fractured coal seams.
46
Liu, K., and J. Zhao. "Progressive Damage Behaviours of Triaxially Confined Rocks under Multiple Dynamic Loads." Rock Mechanics and Rock Engineering 54, no. 6 (May 5, 2021): 3327–58. http://dx.doi.org/10.1007/s00603-021-02408-z.
Повний текст джерелаАнотація:
AbstractInvestigation of rock progressive damage under static confinement and strain rates facilitates the generation mechanism of natural fault damage zones. A triaxial Hopkinson bar apparatus is used to perform dynamic triaxial compression tests to examine the damage and degradation process of rocks subjected to multiple impacts. Dynamic mechanical properties are determined under a static triaxial pre-stress of (30, 20, 10) MPa and multiple dynamic loadings, with the repetitive impact velocity of 27 m/s and strain rates from 50 to 150/s. The acoustic characteristics are identified by ultrasonic measurement to qualify the damage values. The micro-crack parameters, including crack area and volumes are detected using synchrotron X-ray micro-computed tomography (μCT) to characterize the progressive damage. In addition, the microcrack orientation, density and fractal dimension are analysed from thin section. Experimental results show that dynamic stress-strain curves can be divided to elastic, nonlinear deformation and unloading phases. Dynamic peak stress, Young’s modulus and ultrasonic wave velocity decrease with increasing impact times. The high frequency of ultrasonic wave is filtered by the induced microcracks. The progressive damage and evolution of fracture networks are associated highly with microcrack initiation, propagation, branching and coalescence. Shear bands are commonly generated in granite, and tensile cracks are dominant in marble, while sandstone is mainly failed by compaction and deformation band. The absorbed energy of rock increases nonlinearly with increasing crack surface and volume. Besides, microcracks propagate primarily along the maximum principal stress; the density and fractal dimension exhibit an anisotropic distribution controlled by true triaxial confinement and dynamic impacts.
47
Agrizzi, Carlos Paulino, Elaine Aparecida Santos Carvalho, Mônica Castoldi Borlini Gadioli, Gabriela Nunes Sales Barreto, Afonso R. G. de Azevedo, Sérgio Neves Monteiro, and Carlos Maurício Fontes Vieira. "Comparison between Synthetic and Biodegradable Polymer Matrices on the Development of Quartzite Waste-Based Artificial Stone." Sustainability 14, no. 11 (May 24, 2022): 6388. http://dx.doi.org/10.3390/su14116388.
Повний текст джерелаАнотація:
The development of artificial stone from the agglutination of polymeric resin using industrial wastes can be a viable alternative from a technical, economic, and sustainable point of view. The main objective of the present work was to evaluate the physical, mechanical, and structural properties of artificial stones based on quartzite waste added into a synthetic, epoxy, or biodegradable polyurethane polymer matrix. Artificial stone plates were produced through the vacuum vibration and compression method, using 85 wt% of quartzite waste. The material was manufactured under the following conditions: 3 MPa compaction pressure and 90 and 80 °C curing temperature. The samples were characterized to evaluate physical and mechanical parameters and microstructure properties. As a result, the artificial stone plates developed obtained ≤0.16% water absorption, ≤0.38% porosity, and 26.96 and 10.7 MPa flexural strength (epoxy and polyurethane resin, respectively). A wear test established both artificial quartzite stone with epoxy resin (AS-EP) and vegetable polyurethane resin (AS-PU) high traffic materials. Hard body impact resistance classified AS-EP as a low height material and AS-PU as a very high height material. The petrographic slides analysis revealed that AS-EP has the best load distribution. We concluded the feasibility of manufacturing artificial stone, which would minimize the environmental impacts that would be caused by this waste disposal. We concluded that the production of artificial rock shows the potential and that it also helps to reduce environmental impacts.
48
Loch, RJ, and JL Foley. "Measurement of aggregate breakdown under rain - Comparison with tests of water stability and relationships with field measurements of infiltration." Soil Research 32, no. 4 (1994): 701. http://dx.doi.org/10.1071/sr9940701.
Повний текст джерелаАнотація:
This paper reports comparisons between aggregate breakdown on wetting by rainfall with breakdown measured by a range of alternative methods. It also reports correlations between measured breakdown and steady infiltration rates of simulated rain of high and low energy, and hydraulic conductivities of surface seal layers formed under high energy rain. A wide range of soils in eastern Australia were studied. Highly significant correlations were found between measurements of aggregate breakdown to < 125 �m caused by rainfall wetting and both steady infiltration rates and hydraulic conductivities. Significant, but poorer correlations were found between steady infiltration rates and breakdown resulting from immersion wetting. Deletion of swelling soils from the data set greatly improved correlations between steady infiltration rates of high energy rain and breakdown measured by both immersion and tension wetting, showing that these methods of wetting ace particularly inappropriate for swelling soils. No correlation was found between infiltration rates and measured clay dispersion. Different relationships between the proportion of particles (%) < 125 �m at the soil surface (P125) and steady infiltration rates of low and high energy rain indicated that compaction of the soil surface layer, rather than increased aggregate breakdown, is a major cause of surface sealing by raindrop impacts. Measurements of fall cone penetration confirmed that drop impacts had compacted the surface layer. Suctions across the surface seal were related to P125 in that layer, and the relationship obtained was used in calculating hydraulic conductivities. The results confirm that measurement of aggregate breakdown under rainfall wetting produces results of much greater relevance to soil behaviour under field conditions than do tests based on immersion and tension wetting.
49
Escarabajal-Henarejos, David, Dolores Parras-Burgos, Laura Ávila-Dávila, Francisco Javier Cánovas-Rodríguez, and José Miguel Molina-Martínez. "Study of the Influence of Temperature on Boron Concentration Estimation in Desalinated Seawater for Agricultural Irrigation." Water 13, no. 3 (January 28, 2021): 322. http://dx.doi.org/10.3390/w13030322.
Повний текст джерелаАнотація:
After several decades, the incorporation of desalinated seawater into agricultural areas with scarce water resources has become one of the main water supply strategies. Compared to the several currently available desalination techniques, reverse osmosis (RO) is now the reference technology because it lowers energy uses and production costs. Nevertheless, its main limiting factor lies in the membranes used for this system not efficiently retaining boron, which is a problem because the concentration of this element in seawater is high. For 3 years, the present work analysed the impact of seawater temperature on the kinetic parameters of boron rejection in an RO system to establish their annual behaviour and the existing correlation between both parameters. A comparison was made using the values simulated in the projection software provided by the manufacturer of the membranes. The obtained results indicated a high correlation, and the R2 correlation coefficients came very close to the unity. Nonetheless, this correlation lowered with time due to typical membrane ageing and compaction because of the system’s continuous operation. Under the tested working conditions and by applying analysed temperature intervals, it was impossible to reach the 0.3 mg·L−1 boron concentration value that ensures lack of crop toxicity. Thus, incorporating other boron reduction techniques is necessary.
50
Panteleenko, F. I., V. A. Okovity, O. G. Devоino, V. M. Astashinsky, and F. Switala. "Multi-Layers Composite Plasma Coatings Based on Oxide Ceramics and M-Croll." Science & Technique 21, no. 2 (April 6, 2022): 93–98. http://dx.doi.org/10.21122/2227-1031-2022-21-2-93-98.
Повний текст джерелаАнотація:
The paper considers the influence of the parameters of the plasma spraying process on the technological characteristics of multilayer coatings based on nickel-chromium, nickel-chromium-aluminum-yttrium materials, oxide ceramics, intended for operation at high temperature and additional dynamic loads. The design of plasma coatings during their application (with subsequent high-energy processing) under such conditions requires a comprehensive solution – both the use of high-quality powder ingredients and the optimization of technological parameters. The plasma process of applying powder materials has been improved to obtain the maximum values of their utilization factors. The technological characteristics that affect the properties of plasma coatings are optimized, namely: the flow rates of the plasma-forming and materials-transporting gases, the flow rate of supplied powder materials, the current and voltage of the electric arc of the plasma torch, the distance from the plasma torch nozzle exit to the substrate. The paper presents the results of studies of the structure of coatings, performed using scanning electron microscopy. Their analysis has made it possible to form general regularities obtained by the action of radiation of compression plasma flows on coatings formed by air plasma. The considered structures are created using the processes of melting, compaction and high-speed cooling of plasma coatings. The main optimization indicators are the maximum local compaction and spillage of the obtained compositions with the absence of defects and destruction from the impact of compression plasma flows. The main effect during the action of radiation of a compression plasma flow on previously formed coatings is thermal. It contributes heating of the near-surface layer. When the coating is exposed to radiation of compression plasma flows, a remelted layer of oxides with a thickness of about 12–15 µm is created, smoothing the relief of the formed surface and creating a network of cracks on the surface, diverging into the depth of the coating. The liquid-phase processes occurring in the molten phase of the near-surface layers after exposure to compression plasma radiation change the structure of the layers and contribute to the modification of their mechanical properties. By smoothing the surface, increasing the density of the surface crystallized layer and minimizing macro-defects – pores or macrocracks – the mechanical characteristics of the coatings increase.