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1
Tempone, Pamela, Martin Landrø, and Erling Fjær. "4D gravity response of compacting reservoirs: Analytical approach." GEOPHYSICS 77, no. 3 (May 1, 2012): G45—G54. http://dx.doi.org/10.1190/geo2010-0361.1.
Повний текст джерелаАнотація:
Time-lapse gravity is a technique sensitive to subsurface change in mass and in mass distribution. We attempted to devise a method to predict gravity effects caused by redistribution of subsurface mass induced by reservoir compaction. First, displacements and strains due to compaction were modeled using a geomechanical model. Then, 4D gravity effects were derived from the displacements and the volumetric strains computed in and around the reservoir. A sensitivity study was carried out for geomechanical parameters, such as Poisson’s ratio, as well as for geometrical parameters, such as reservoir radius and depth. Finally, changes in gravity due to compaction were compared to changes induced by reservoir fluid substitution. Given a rigid basement close below a strongly compacting reservoir, our modeling case showed that the deformation itself could give gravity changes comparable to changes caused by reservoir fluid density changes, which are the changes traditionally targeted by gravity monitoring. For a homogeneous subsurface, the compaction gave negligible gravity changes for our modeling case.
2
Kurniawan, Eko, Nelvia Nelvia, and Wawan Wawan. "Phisycal And Chemical Properties And Nutrient Content (N, P, K, Mg, B, Cu And Zn ) In Oil Palm Leaf In Various Of Age After Compacting." JURNAL AGRONOMI TANAMAN TROPIKA (JUATIKA) 2, no. 2 (July 4, 2020): 86–100. http://dx.doi.org/10.36378/juatika.v2i2.508.
Повний текст джерелаАнотація:
Planting of oil palm in peatland has been limited by soil physical, chemical properties, and hydrology, that`s way needed improvement on those matters to increase the productivity of peat and oil palm in peat soil by compacting. The purpose of this compacting is to improve the soil's physical, chemical properties, and soil moisture. A sampling of soil, water, and leaf were done in consecutive block 5,4,3,2,1,0 year after compacting and of planting done 4 years 10 months, 3 years 9 months, 2 years 9 months, 1 year 10 months, 11 months and 2 months, control used in this trial are origin condition (forest). Increasing bulk density was found at compacting block with 30 cm depth from the surface with the lower in 2 years after compacting at 0.09 g/cm3 and highest 4 years after compacting 0.4 g/cm3. In-depth of 60 cm from surface was found no increasing the bulk density 3 years after compacting 0.0 g/cm3 and the highest on 5 years after compacting 0.3 g/cm3 compared to forest. Decreasing on permeability in-depth 30 cm at 4 years after compacting 7.47 cm/jam and close to forest permeability 51.11 cm/hour is 2 years 43.6 cm/hour. As represent rise capillary consistently water content ≥ 80% achieved at depth 20 cm of surfaces on all block. Compaction doesn't regard pH, C organic, basa's saturation, capacity exchange cation. On depth 30 cm P-total lower on s without compaction at 599.6 ppm and above 871.6 ppm on 5 yr than forest 585 ppm. P available most low 58.1 ppm happens on 4 yr afters is compacted and p available forest 53.9 ppm. Nutrient content B, Cu and Zn at soil not influenced by compaction. Fosfor (P) in water increases with added years after compaction lower at 39.1 mg/L in the block without compaction compare of forest that 40.8 mg/L. Leaf nutrient rate on compacted block on optimum until excess where N (2. 69 – 3.15 %) , P (0. 170 – 0.209 %) , K( 0. 952 – 1.11%) , Mg ( 0. 377 – 0.497%) , except on block without compacting K (0. 830 %) and Mg (0. 190%) at deficiency and 0 years afters compaction Mg leaf on level deficiency 0. 230%. Nutrient content of B, Cu and Zn at various level and not influenced by compacting.
3
Cabot, Louis, and Jean-Pierre Le Bihan. "Quelques propriétés d'une argile sur la « ligne optimale de compactage »." Canadian Geotechnical Journal 30, no. 6 (December 1, 1993): 1033–40. http://dx.doi.org/10.1139/t93-100.
Повний текст джерелаАнотація:
This paper deals with the evolution of the texture of the clay during compaction and with the importance of maintaining a close correlation between the degree of compaction and the water content to obtain a sealed fill with a homogeneous texture. The results of laboratory tests show the orderly evolution of some physical and mechanical properties of the compacted clay along this optimal correlation of compaction. Finally, the results of the control tests on the clay of the core of Kompienga dam compacted according to these specifications are presented. Key words : compacted clay, texture, macroporosity, optimal line of compaction, evolution of properties, specifications of compaction.
4
Wang, Fuyu, Weichen Pang, Yuan Fang, Yingjun Jiang, Leilei Han, and Yanling Li. "Comparative Research on Mechanical Properties and Void Distribution of Cement Stabilized Macadam Based on Static Pressure and Vibration Compaction." Applied Sciences 10, no. 24 (December 10, 2020): 8830. http://dx.doi.org/10.3390/app10248830.
Повний текст джерелаАнотація:
Cement stabilized macadam semi-rigid base materials are widely used in road construction in China. However, a traditional static molding method and heavy compaction method cannot guide the design and engineering application of cement stabilized macadam mixture because it often appears that the compaction degree exceeds 100% in the practical engineering. In view of this, this paper carried out the research of an indoor vibration compaction method of cement stabilized macadam mixture, and compared the mechanical properties and void distribution characteristics of two kinds of compositions of mixtures under the vibration compaction method as well as static pressure molding and heavy compaction method and on-site sample after 7 days curing period, which was combined with the physical engineering project of Yu-Song Expressway in Jilin Province, China. The research results show that the maximum dry density of mixture under vibration compaction is larger and the best moisture content is smaller, which has a heavy incomparable advantage on the simulation of on-site compaction. And the compressive strength and splitting strength indexes of vibration compacted specimens are close to those of an on-site sample, which are all larger than static pressure specimen. Moreover, the void distribution characteristics of vibration compacted specimens is much closer to those of the on-site sample and more universal, while static pressure specimens lack in uniformity. In addition, different results caused by the two gradation are compared. All of the above research results can verify that the vibration compaction method has more reliability and accuracy to simulate the actual properties of base material. This study provides a reference for the application of vibration compaction method in road engineering design.
5
Hawley, Robert L., and Edwin D. Waddington. "In situ measurements of firn compaction profiles using borehole optical stratigraphy." Journal of Glaciology 57, no. 202 (2011): 289–94. http://dx.doi.org/10.3189/002214311796405889.
Повний текст джерелаАнотація:
AbstractWe have developed a technique in which we use a borehole video camera and post-processing software to make a record of the optical brightness as a function of depth in polar firn. We call this method borehole optical stratigraphy. To measure firn compaction, we note the positions of optical features on the borehole wall detected by an initial ‘baseline’ log. We track the displacements of these features in subsequent logs. The result provides a measurement of the relative vertical motion and thus compaction of the firn over the survey period. We have successfully used this system at Summit, Greenland, to measure the depth distribution of firn column shortening experienced in a borehole over three 1 year periods. The uppermost 30 m of the firn at Summit is compacting as predicted by a simple steady-state model, implying that the firn density profile at Summit is at or close to steady state over the past ∼70 years.
6
Khong, Anthony, and Roy Parker. "mRNP architecture in translating and stress conditions reveals an ordered pathway of mRNP compaction." Journal of Cell Biology 217, no. 12 (October 15, 2018): 4124–40. http://dx.doi.org/10.1083/jcb.201806183.
Повний текст джерелаАнотація:
Stress granules (SGs) are transient membraneless organelles of nontranslating mRNA–protein complexes (mRNPs) that form during stress. In this study, we used multiple single-molecule FISH probes for particular mRNAs to examine their SG recruitment and spatial organization. Ribosome runoff is required for SG entry, as long open reading frame (ORF) mRNAs are delayed in SG accumulation, indicating that the SG transcriptome changes over time. Moreover, mRNAs are ∼20× compacted from an expected linear length when translating and compact ∼2-fold further in a stepwise manner beginning at the 5′ end during ribosome runoff. Surprisingly, the 5′ and 3′ ends of the examined mRNAs were separated when translating, but in nontranslating conditions the ends of long ORF mRNAs become close, suggesting that the closed-loop model of mRNPs preferentially forms on nontranslating mRNAs. Compaction of ribosome-free mRNAs is ATP independent, consistent with compaction occurring through RNA structure formation. These results suggest that translation inhibition triggers an mRNP reorganization that brings ends closer, which has implications for the regulation of mRNA stability and translation by 3′ UTR elements and the poly(A) tail.
7
Czech, Krzysztof R., and Wojciech Gosk. "Impact of the Operation of a Tri-band Hydraulic Compactor on the Technical Condition of a Residential Building." Applied Sciences 9, no. 2 (January 18, 2019): 336. http://dx.doi.org/10.3390/app9020336.
Повний текст джерелаАнотація:
The study investigates the surface vibrations generated by a new generation, tri-band hydraulic compactor type V8 from Maschinentechnik Schrode AG (MTS), and a reversible plate compactor type DPU 6055 from Wacker Neuson in close proximity to a low-rise residential building. Compaction works were carried out in three stages, at distances: 15 m, 10 m, and 5 m from the building, and at three depths: 0.4 m, 1.2 m, and 1.8–2.0 m. The research was conducted at one measurement point, located on the outer foundation wall of the building, and at three measurement points located on the ground at distances of 1.25–7.5 m from the building. The study analyses the distribution of peak component particle accelerations at the ground, and peak component particle velocities at the foundation wall of the building as a function of the distance of compactors from the building and the depth of compaction works, as well as the mode of work of hydraulic compactor type V8 from MTS. The study contains the comparison of the permissible vibration levels that are recommended by selected European standards (DIN, BS, VSS, and PL) and an approximate assessment of the impact of vibrations on the technical condition of the residential building.
8
Han, P., X. Z. An, Y. X. Zhang, and Z. S. Zou. "FEM modeling on the compaction of Fe and Al composite powders." Journal of Mining and Metallurgy, Section B: Metallurgy 51, no. 2 (2015): 163–71. http://dx.doi.org/10.2298/jmmb150210020h.
Повний текст джерелаАнотація:
The compaction process of Fe and Al composite powders subjected to single action die compaction was numerically modeled by FEM method. The relationship between the overall relative density and compaction pressure of the compacts with various Al contents was firstly identified, and the influences of Al content on the local relative density, stress, and their distributions were studied. Then the compaction pressure effects on the above properties with fixed Al content were discussed. Furthermore, detailed flow behaviors of the composite powders during compaction and the relationship between the compaction pressure and the ejection force/spring back of the compact were analyzed. The results show that: (1) With each compaction pressure, higher relative density can be realized with the increase of Al content and the relative density distribution tends to be uniform; (2) When the Al content is fixed, higher compaction pressure can lead to composite compact with higher relative density, and the equivalent Von Mises stress in the central part of the compact increases gradually; (3) Convective flow occurs at the top and bottom parts of the compact close to the die wall, each indicates a different flow behavior; (4) The larger the compaction pressure for each case, the higher the residual elasticity, and the larger the ejection force needed.
9
Smith, James Edward, and Edward Millard Smith-Rowland. "Proposed Model for Shale Compaction Kinetics." Geosciences 11, no. 3 (March 15, 2021): 137. http://dx.doi.org/10.3390/geosciences11030137.
Повний текст джерелаАнотація:
Shales are the most abundant class of sedimentary rocks, distinguished by being very fine-grained, clayey, and compressible. Their physical and chemical properties are important in widely different enterprises such as civil engineering, ceramics, and petroleum exploration. One characteristic, which is studied here, is a systematic reduction of porosity with depth of burial. This is due increases in grain-to-grain stress and temperature. Vertical stress in sediments is given by the overburden less the pore fluid pressure, σ, divided by the fraction of the horizontal area which is the supporting matrix, (1−φ), where φ is the porosity. It is proposed that the fractional reduction of this ratio, Λ, with time is given by the product of φ4m/3, (1−φ)4n/3, and one or more Arrhenius functions Aexp(−E/RT) with m and n close to 1. This proposal is tested for shale sections in six wells from around the world for which porosity-depth data are available. Good agreement is obtained above 30–40 °C and fractional porosities less than 0.5. Single activation energies for each well are obtained in the range 15–33 kJ/mole, close to the approximate pressure solution of quartz, 24 kJ/mol. Values of m and n are in the range 1 to 0.8, indicating nearly fractal water-wet pore-to-matrix interfaces at pressure solution locations. Results are independent of over- or under-pressure of pore water. This model attempts to explain shale compaction quantitatively. For the petoleum industry, given porosity-depth data for uneroded sections and accurate activation energy, E, paleo-geothermal-gradient can be inferred and from that organic maturity, indicating better drilling prospects.
10
Jiao, Ming Hua, Long Sun, Man Gu, De Guang Wang, and Yu Cheng Wu. "Mesoscopic Simulation on the Compression Deformation Process of Powder Particles." Advanced Materials Research 753-755 (August 2013): 896–901. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.896.
Повний текст джерелаАнотація:
The compression deformation processes of powder particles were investigated by the way of mesoscopic simulation based on finite element method of discrete body. The strain process of the particles in typical position, the deformation difference of the particles in different positions and the strain status of particles were investigated under various compacting pressure. The results show that the deformation process of the compressed powder particles consisted of three stages, which were the initial stage of small deformation, the major stage of the sharply changes of strain and the ultimate stage of strain tending to stable state. The interface friction has a significant influence on the deformation and pressed density of particles close to die wall. The density can not be increased with the increase of compacting pressure of compaction infinitely.
11
Wu, Chuan Yu, A. C. Bentham, and A. Mills. "Analysis of Failure Mechanisms during Powder Compaction." Materials Science Forum 534-536 (January 2007): 237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.237.
Повний текст джерелаАнотація:
Powder compaction is a well-established process for manufacturing a wide range of products, including engineering components and pharmaceutical tablets. During powder compaction, the compacts (green bodies or tablets) produced need to sustain their integrity during the process and possess certain strength. Any defects are hence not tolerable during the production. Therefore, understanding failure mechanisms during powder compaction is of practical significance. In this paper, the mechanisms for one typical failure, capping, during the compaction of pharmaceutical powders were explored. Both experimental and numerical investigations were performed. For the experimental study, an instrumented hydraulic press (a compaction simulator) with an instrumented die has been used, which enable the material properties to be extracted for real pharmaceutical powders. Close attentions have been paid to the occurrence of capping during the compaction. An X-ray Computed Microtomography system has also used to examine the internal failure patterns of the tablets produced. Finite element (FE) methods have also been used to analyse the powder compaction. The experimental and numerical studies have shown that the shear bands developed at the early stage of unloading appear to be responsible for the occurrence of capping. It has also been found that the capping patterns depend on the compact shape.
12
Huang, Bao Tao, Xin Yuan, Jie Zhou, and Ding Liu. "Numerical Simulation of Vibration Compacting Process on Hydrous Embankment by Discrete Element Method." Advanced Materials Research 594-597 (November 2012): 506–11. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.506.
Повний текст джерелаАнотація:
In this article, the discrete element method is used to investigate the coarse particle material close-grained space structure evolutionary process submitted to a vibrating compressive load. 2-D generation algorithm about irregular particle generation and particle contact interface generation was adopted. Irregular particles were randomly generated in the designated categories with this algorithm. The microcosmic material parameters are endowed to irregular particle and pore space. The microcosmic material parameters are also endowed to water. The irregular micro-particles close-grained process was been analyzed under vibrating compressive. The numerical simulation results demonstrate that the coarse-grained soil Irregular particles compacting effect of the simulation results with the actual theoretic situation in the basic line. The Irregular particles were whirligig and movement, location of the rearrangement as a whole to show the close-grained process. The use of discrete element method can be clearly informed that the simulation of the embankment particles in the body vibration. This research offers a new idea and continent method for compaction dense of hydrous embankment.
13
Santiago, Ordóñez Salazar, Eduardo Aguirre Maldonado, and Cristian Balcázar Arciniega. "Preparation of a Rice Husk Composite and Effects of Cold Pressing on the Flexural Strength Properties." Materials Science Forum 1023 (March 2021): 69–74. http://dx.doi.org/10.4028/www.scientific.net/msf.1023.69.
Повний текст джерелаАнотація:
The study of composites made from residual organic materials and polymeric resins, has a great projection due to the use of new raw materials and the good physical, mechanical and aesthetic characteristics these materials present in the construction industry. The manufacturing processes of these composites include the necessary pressure application to generate an efficiently compact material, where matrix and reinforcement bonding are efficient. This study defines how the compaction force influences the flexural strength of composites made from polyester resin as polymer matrix, and rice husk as reinforcement material. This is achieved by testing different series of specimens, made by applying different compaction forces in a cold process, to analyse the relationship between compaction and flexural strength. Specimens are made varying only the compaction force, from 2, 5, 8, 11, 14, and 17 tons. The results show that, when the compaction force increases, the flexural strength in the composites also increases, however, there is a pressure range where the flexural strength values are very close, conditioning the use of pressure in relation to the decrease in the specimen section.
14
Zhang, Bao, Idris K. Mohammed, Yi Wang, and Daniel S. Balint. "On the use of HCP and FCC RVE structures in the simulation of powder compaction." Journal of Strain Analysis for Engineering Design 53, no. 5 (May 10, 2018): 338–52. http://dx.doi.org/10.1177/0309324718774188.
Повний текст джерелаАнотація:
Use of hexagonal close packed and face centered cubic structures to simulate powder compaction reveals that plastic deformation is effective in reducing porosity until a relative density of 0.96, beyond which a drastic rise in pressure is required. The compaction process can be divided into three phases demarcated by relative densities of 0.8 and 0.92, characterized, respectively, by local yielding around the initial contact point, coalescence of locally yielded zones and full plastic flow to reduce pores. The macroscopic yield behaviour of the powder assembly in the present work agrees reasonably with analytical and numerical models such as the Storåkers-Fleck-McMeeking model and multi-particle finite element model. It is found that for rate-dependent powder materials, the compaction process is noticeably rate dependent from a relative density of 0.85. Although a regular packing of powders is unrealistic, the understanding gained from a regular packing model provides insight into the role that plastic deformation plays during powder compaction.
15
Hettema, M. H. H., P. M. T. M. Schutjens, B. J. M. Verboom, and H. J. Gussinklo. "Production-Induced Compaction of a Sandstone Reservoir: The Strong Influence of Stress Path." SPE Reservoir Evaluation & Engineering 3, no. 04 (August 1, 2000): 342–47. http://dx.doi.org/10.2118/65410-pa.
Повний текст джерелаАнотація:
Summary The decrease of pore pressure during hydrocarbon production (depletion) leads to compaction of the reservoir, which in turn changes the stresses acting on the reservoir. The prediction of reservoir compaction and its consequences is usually based on laboratory experiments performed under uniaxial strain conditions, i.e., allowing no lateral strain during depletion. Field data of the Groningen gas field (The Netherlands) indicate that the stress development of the field deviates significantly from the stress path under uniaxial strain conditions. Laboratory experiments show that the applied stress path has a strong influence on the depletion-induced compaction behavior. We discuss the consequences of these results for the field compaction behavior by considering the responsible deformation mechanisms active in reservoir and experiment. The new Groningen field data, in combination with our experimental results, provide an explanation for the difference between the prediction of compaction and subsidence based on uniaxial experiments and the measurement of compaction and subsidence in the Groningen field. With the use of the new stress path, the predicted and measured compaction and subsidence are in agreement. Introduction The prediction of the amount of depletion-induced reservoir compaction and its adverse consequences (such as subsidence, casing deformation, and seismicity) requires three types of input parameters: The mechanical behavior of the reservoir rock and the rock surrounding the reservoir, the reservoir stress path induced by the depletion, and the dimension and depth of reservoir and overburden formations. Also, a model is required to upscale the laboratory experiments to predict reservoir compaction and the associated surface or seabed subsidence during and after depletion. The first two types of input parameters (mechanical behavior and stress path) are actually linked: The depletion leads to compaction and deformation of the reservoir, which in turn changes the total stresses acting on the reservoir. It is the combination of pore pressure change and total stress change, which alters (and generally increases) the effective normal and shear stresses acting on the load-bearing grain framework. This results in elastic (recoverable) and inelastic (permanent) deformation which, in turn, has a time-independent component, usually referred to as plasticity, and a time-dependent component, referred to as creep. The bulk rock compaction is the result of the various micro mechanisms activated by the depletion, and their dependence on stress path and stress rate (typically, a few MPa per year), stress level (<100 MPa), and temperature (<200°C) and possibly also pore fluid composition.1–3 Ideally, the laboratory experiments are performed along the same stress path that the reservoir undergoes during depletion. However, the reservoir stress path is not known before depletion starts, and analytical or numerical models for the stress development in depleting reservoirs are very sensitive to the input parameters mentioned earlier. To make things worse, field data describing depletion-induced changes in total stress are very scarce, so only a few case studies are available to guide the design of laboratory experiments. In most studies it is assumed that the reservoir compacts uniaxially; that is, there is only vertical compaction and no horizontal deformation. During uniaxial compaction of sandstone with 10 to 30% porosity, the ratio of change in total horizontal stress per change in pore pressure is typically in the range 0.7 to 0.9.3 For the Groningen gas reservoir (The Netherlands) a similar strategy was followed, and a large amount of uniaxial compaction experiments were performed, partly published.3 The tested rock types ranged from low-porosity (5 to 10%) conglomerates to highly porous (25 to 30%) coarse sandstone. However, the compaction and subsidence prediction based on these uniaxial strain experiments is larger than the measured compaction and subsidence in the Groningen field, and the reason for this is still unknown. This paper describes the important role of stress path in compaction prediction and offers a new explanation for the difference in predicted and measured compaction and subsidence in the Groningen field. We start with an analysis of the changes of the total stresses during reservoir compaction, using basic rock mechanics theory. Then, new field stress data are presented and analyzed to estimate the production-induced stress path of the Groningen gas field. Next, the results of triaxial compaction experiments on Groningen core samples are shown, indicating a strong influence of stress path on compaction. Finally, we discuss the experimental results and the consequences of the stress path to the compaction behavior by considering the underlying compaction mechanisms. Although we discuss only field data and core measurements from the Groningen gas field, we think that our conclusions can be generalized, and may be of value to other studies aimed at the prediction of depletion-induced reservoir compaction. Reservoir Stress Changes During Production Prior to production, the Earth's stress field determines the state of stress in the reservoir. Production causes a decrease of the fluid and/or gas pressure in the pores. These pressure changes also result in changes in the total vertical and horizontal stresses acting on the reservoir. Strong evidence for this comes from the occurrence of seismic events inside and close to compacting reservoirs.4,5 Geertsma6 developed a theory of the subsidence and stress changes associated with reservoir compaction, based on linear poroelastic rock behavior. Regarding the total vertical stress, the depletion-induced stress changes at the axis just above a disk-shaped compacting reservoir can be written as6 Δ σ V = h Δ p r ( 1 − 2 ν 2 − 2 ν ) f ( d r ) . ( 1 )
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Zhu, Caihui, Xiaosong Zhou, and Songhe Wang. "Foundation Treatment Assessment and Postconstruction Settlement Prediction of a Loess High Fill Embankment: A Case Study." Shock and Vibration 2020 (November 12, 2020): 1–22. http://dx.doi.org/10.1155/2020/8864690.
Повний текст джерелаАнотація:
The design of high fill embankments (HFEs) on the loess plateau requires proper foundation treatment methods and reasonable prediction of postconstruction settlement (PCS). In situ tests were carried out on a test section of the collapsible loess foundation of a high fill airport to assess the reinforcement effects of common treatment methods. Based on in situ monitored data, the spatial-temporal variations of the PCS of the HFE were investigated, with a simple empirical formula proposed for PCS prediction. The PCS increases linearly with the fill thickness, and the PCS rate varies exponentially with the fill rate. Two engineering recommendations were made to reduce differential PCS and water damage for the test site. The first is to combine the reinforcement methods to reduce PCS of the HFE, i.e., dynamic compaction for loess foundation with lower water content and gravel piles with stabilizers for that with higher water content. The second is to employ the dynamic compaction (DC), percussive compaction (PC), and vibration compaction (VC) to strengthen the fill to reach an average compaction degree above 0.93 and a water content close to the optimal.
17
Zhang, T. W., Y. J. Cui, F. Lamas-Lopez, N. Calon, and S. Costa D’Aguiar. "Compacted soil behaviour through changes of density, suction, and stiffness of soils with remoulding water content." Canadian Geotechnical Journal 55, no. 2 (February 2018): 182–90. http://dx.doi.org/10.1139/cgj-2016-0628.
Повний текст джерелаАнотація:
To better understand the overall hydromechanical behaviour of interlayer soil, the compaction behaviour of one of the two components — the portion of fines (<4 mm) that is sensitive to water content changes — was investigated. The standard Proctor compaction curves were first determined for the soils. Then, the maximum shear modulus, Gmax, and suction were measured on samples statically compacted at an identical dry density, but different remoulding water contents. The changes in Gmax reveal the existence of a characteristic water content corresponding to the maximum Gmax. The results also show that this characteristic water content increases with the soil plasticity, being similar to the variation trend of optimum water content with soil plasticity. A bimodal pattern was observed from the plot of total suction ψ versus the slope of water content w–log(ψ) curve. The suction corresponding to the maximum Gmax is close to the lowest point between the two peaks in the ψ–dw/dlog(ψ) curve. A reasonable explanation was attempted for the correspondence between the “optimum water content” defined by the maximum value of Gmax and the corresponding suction. The difference between the static and dynamic compactions was also explained in terms of suction values.
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Porozova, S. E., V. B. Kul’met’eva, T. Yu Pozdeeva, and V. O. Shokov. "Role of nanopowder agglomerates in forming the structure and properties of ceramic materials." Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya, no. 4 (December 15, 2020): 4–13. http://dx.doi.org/10.17073/1997-308x-2020-4-4-13.
Повний текст джерелаАнотація:
A comparative analysis of agglomerates obtained by spray drying and granulation methods and consolidated materials based on them was carried out. The paper provides the results obtained when studying zirconia nanopowders granulated in water medium with an agar agar additive obtained by chemical precipitation with zirconia partially stabilized by yttrium oxide (2.5 mol.%), and TZ-3Y-E powder manufactured by Tosoh Corp. (Japan) that was prepared by spray drying. Agglomerates as well as microsections and fractures of samples were studied by scanning electron, optical, atomic force microscopy, and Raman spectroscopy. The crack resistance coefficient (K1с) of samples was determined by indenting the polished surface of microsections with a Vickers pyramid. The specific surface of the powders measured by nitrogen thermal desorption during granulation remains unchanged indicating a significant open porosity of agglomerates obtained. With increasing compacting pressure under conditions of semi-dry compaction with an aqueous solution of PVA as a binder, agglomerates and even aggregates of granulated powders are destroyed, K1с increases with increasing compaction pressure and the accompanying material microstructure grinding. Powders agglomerated using spray drying break up much less intensively, K1с does not change with increasing pressure. The studies conducted allow us to agree with the authors pointing to the fractal nature of agglomerates obtained from chemically precipitated nanopowders without the use of spray drying. The use of granulated nanopowders in semi-dry compaction with the application of high pressures makes it possible to destroy not only agglomerates, but also aggregates, and to obtain nanostructured ceramics with grain sizes close to the size of initial particles.
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Kuzovkina, Yulia A., Michael Knee, and Martin F. Quigley. "Effects of Soil Compaction and Flooding on the Growth of 12 Willow (Salix L.) Species." Journal of Environmental Horticulture 22, no. 3 (September 1, 2004): 155–60. http://dx.doi.org/10.24266/0738-2898-22.3.155.
Повний текст джерелаАнотація:
Abstract Responses to soil compaction and flooding by 12 Salix species were studied in small mesocosms in a greenhouse over a period of 8 weeks. Two independent experiments were conducted: response of rooted cuttings to soil compaction and response of the same species to three weeks of flooding. Soil atmosphere was analyzed in all treatments. Regardless of level of compaction, oxygen levels were stable and close to atmospheric proportions. However, concentration of carbon dioxide gradually increased in compacted treatments and was the highest in the most compacted soil. Concentration of ethylene remained more or less stable in the compaction treatments. In the flooding treatments a significant decrease of oxygen concentration (9.1%), and significant increases of carbon dioxide (2.15%) and ethylene (1.57μl/liter) took place. All species except S. amygdaloides produced equal or higher biomass in compacted soil compared to a control. Flooding had little effect on the growth of above or below ground parts for most species. Anaerobic conditions triggered a wide range of morphological adaptations: lenticel hypertrophy, formation of adventitious roots (including roots with enhanced aerenchyma), roots growing along the water surface, and roots exhibiting negative gravitropism. Our principal finding was that neither soil compaction nor flooding caused significant reduction in growth of willows.
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Cheng, Zhiqiang, De Zhang, Shengjia Xie, Pawel Andrzej Polaczyk, and Tao Wang. "SmartRock-Based Research on Gyratory Locking Point for Stone Mastic Asphalt Mixture." Buildings 12, no. 2 (January 20, 2022): 97. http://dx.doi.org/10.3390/buildings12020097.
Повний текст джерелаАнотація:
For gyratory compaction, the concept of the locking point was initially developed to identify the compactability of asphalt mixes and to alleviate potential aggregate crushing in the mold. Most previous studies on the locking point were based on specimens’ height change. Recent studies have indicated that the gyratory locking point of cold mix asphalt mixtures could be determined by the rotation angle range indicator using SmartRock. However, height or rotation angle change ultimately reflects a change in volume. Additionally, there is no clear physical and mechanical connection between the volume change and the gyratory locking point. In this paper, a stone mastic asphalt mixture (SMA 13) was selected for gyratory compaction applying various compaction temperatures. The compaction data were recorded by a SmartRock embedded in different positions. Collected data included stress, rotation angle, and acceleration. The major findings are as follows: (1) the specimen’s locking point could be determined based on a representative stress value when the SmartRock was embedded in the specimen’s center, and the results are close to the traditional evaluation results (LP3 or LP2-2-3); (2) the representative rotation angle value reached a plateau earlier than the representative stress value; (3) the representative acceleration value is not suitable for characterizing the interlocking process during gyratory compaction.
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Singh, Ranjodh, and Harvinder Singh. "Shear Strength Models for Steel Fibre Reinforced Concrete Beams: Current Scenario." Civil Engineering Journal 7, no. 2 (February 1, 2021): 399–406. http://dx.doi.org/10.28991/cej-2021-03091661.
Повний текст джерелаАнотація:
This review paper presents a comprehensive comparative analysis of various studies conducted on the shear strength of Self-compacting Concrete (SCC) and Normally Vibrated Concrete (NVC) in order to determine the sustainability and affordability of SCC as a construction material. Compaction is the main factor in concrete production. NVC needs compaction and vibration to remove the entrapped air which is both expensive and time-consuming. But SCC has flow ability and passing ability. Although SCC takes a greater amount of paste content, thereby raising the cost of building material, yet the use of such waste material as fly ash, silica, etc. comes in handy as paste content. Thus, the advantages offered by SCC in terms of increased strength as well as cost reduction makes it a highly desirable construction material. The review has selected the works of some eminent scholars on concrete and has analyzed them through individual as well as comparative perspective. A close analysis has helped filter out relevant works for the current study. This process of selection has proved helpful to include most standard works available in the review. Major findings have been enlisted at the end and ways to improve concrete behaviour have been suggested. Doi: 10.28991/cej-2021-03091661 Full Text: PDF
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Bernat-Maso, E., L. Gil, M. J. Lis, and E. Teneva. "Soil biostabilisation and interaction with compaction processes for earthen engineering structures production." Materiales de Construcción 71, no. 343 (August 17, 2021): e256. http://dx.doi.org/10.3989/mc.2021.00221.
Повний текст джерелаАнотація:
Interaction between microbially induced calcium carbonate precipitation (MICP) and compaction procedures to stabilise raw soil materials has been studied with the aim of producing earthen engineering structures. Initial tests to optimise MICP in aqueous medium and in selected soils were performed. MICP and compaction were finally applied to assess medium-size elements. The main result was that sandy soils should be compacted before irrigation treatment to close the existing voids and prevent bacterial sweeping, whereas clayey soils should be compacted after irrigation treatment to avoid the plugging effect. MICP improved small sand soil compressive strength by up to 32% over the value reached by compaction alone. However, MICP had no positive effect on coarse soils and soils with an optimum particle size distribution: MICP treatment was not able to fill large connected voids in the first case and it caused little void generation due to bacteria sporulation in the second.
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Galambošová, Jana, Miroslav Macák, Vladimír Rataj, Marek Barát, and Paula Misiewicz. "Determining Trafficked Areas Using Soil Electrical Conductivity – A Pilot Study." Acta Technologica Agriculturae 23, no. 1 (March 1, 2020): 1–6. http://dx.doi.org/10.2478/ata-2020-0001.
Повний текст джерелаАнотація:
AbstractIncrease in machinery size and its random traffic at fields cause soil compaction resulting in damage of soil structure and degradation of soil functions. Nowadays, rapid methods to detect soil compaction at fields are of high interest, especially proximal sensing methods such as electrical conductivity measurements. The aim of this work was to investigate whether electromagnetic induction (EMI) could be used to determine trafficked areas in silty clay soil. Results of randomized block experiment showed a high significant difference (p <0.01) in EMI data measured between compacted and non-compacted areas. EMI readings from compacted areas were, on average, 11% (shallow range) and 9% (deep range) higher than non-compacted areas, respectively. This difference was determined in both shallow and deep measuring ranges, indicating that the difference in soil compaction was detected in both topsoil and subsoil. Furthermore, the data was found to have a significant spatial variability, suggesting that, in order to detect the increase in EMI (which shows the increase in soil compaction), data within close surrounding area should be included in the analyses. Correlation coefficient of EMI and penetration resistance (average moisture content 32.5% and 30.8% for topsoil and subsoil) was found to be 0.66.
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Lee, Jong Keuk, Soon Jik Hong, Min Ku Lee, and Chang Kyu Rhee. "Fabrication of High-Density Nanostructured Alumina by the Combined Processes of Magnetic Pulsed Compaction (MPC) and Spark Plasma Sintering (SPS)." Solid State Phenomena 118 (December 2006): 597–602. http://dx.doi.org/10.4028/www.scientific.net/ssp.118.597.
Повний текст джерелаАнотація:
In this study the nanostructured α-Al2O3 ceramics has been fabricated by the combined application of magnetic pulsed compaction (MPC) and spark plasma sintering (SPS), and their density and hardness properties were investigated. The α-Al2O3 prepared by the combined processes showed an increase of 8.4 % in density, approaching a value close to the theoretical density, a enhancement by 210∼400 Hv in hardness, compared to those for the ones by the MPC or static compaction method followed by a sintering treatment. Its grain size was almost equivalent to or slightly higher than the size of the starting Al2O3 powder, suggesting that the grain growth was remarkably reduced during the MPC and SPS processes.
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Eppanapelli, Lavan, Fredrik Forsberg, Johan Casselgren, and Henrik Lycksam. "3D Analysis of Deformation and Porosity of Dry Natural Snow during Compaction." Materials 12, no. 6 (March 13, 2019): 850. http://dx.doi.org/10.3390/ma12060850.
Повний текст джерелаАнотація:
The present study focuses on three-dimensional (3D) microstructure analysis of dry natural snow during compaction. An X-ray computed microtomography (micro-CT) system was used to record a total of 1601 projections of a snow volume. Experiments were performed in-situ at four load states as 0 MPa, 0.3 MPa, 0.6 MPa and 0.8 MPa, to investigate the effect of compaction on structural features of snow grains. The micro-CT system produces high resolution images (4.3 μm voxel) in 6 h of scanning time. The micro-CT images of the investigated snow volume illustrate that grain shapes are mostly dominated by needles, capped columns and dendrites. It was found that a significant number of grains appeared to have a deep hollow core irrespective of the grain shape. Digital volume correlation (DVC) was applied to investigate displacement and strain fields in the snow volume due to the compaction. Results from the DVC analysis show that grains close to the moving punch experience most of the displacement. The reconstructed snow volume is segmented into several cylinders via horizontal cross-sectioning, to evaluate the vertical heterogeneity of porosity distribution of the snow volume. It was observed that the porosity (for the whole volume) in principle decreases as the level of compaction increases. A distinct vertical heterogeneity is observed in porosity distribution in response to compaction. The observations from this initial study may be useful to understand the snow microstructure under applied stress.
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Śnieg, Kinga, and Dariusz Błażejczak. "Prediction of Pre-Compression Stress of Soil with Uniaxial Test." Agricultural Engineering 23, no. 1 (March 1, 2019): 95–103. http://dx.doi.org/10.1515/agriceng-2019-0009.
Повний текст джерелаАнотація:
AbstractThe paper presents a concept of determination of pre-compression stress. It assumes that the stress value is close to the unit pressure value which is indispensable to increase the initial degree of soil compaction. Thus, an attempt was made to develop an empirical model for predicting the value of stress at which the initial compaction of a soil sample increases by a determined value. Samples with the so-called intact structure (NS) and soil material in the form of loose mass were collected from subsoil, and they were used to form model samples. Both types of samples were uniaxially compressed. For the study, data on moisture and dry bulk density of model samples were used, as well as determined ratios (conversion factors) that present relations between the results of compaction of model samples and samples with the intact structure. It was reported that the pressure necessary for the increase of the initial compaction of the model samples with the value of +0.05 or +0.10 g∙cm−3 were higher than the formation pressure respectively by 1.03-1.11 and 1.42-1.93 times. It was proved that for determination of the pre-compression stress of the NS samples models of linear regression for prediction the pressure needed to increase the initial compaction of the model sample by the value of +0.05 g∙cm−3, combined with a coefficient calculated for the present state of the soil properties, can be applied.
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Silva, Jeisa Cruz da, Nelci Olszevski, Janielle Souza Pereira, and Edson Pereira da Silva. "INFLUENCE OF SOIL COMPACTION LEVELS ON COWPEA PRODUCTION." REVISTA ENGENHARIA NA AGRICULTURA - REVENG 28 (January 28, 2020): 1–10. http://dx.doi.org/10.13083/reveng.v28i.920.
Повний текст джерелаАнотація:
Cowpea, a short-cycle legume with large production in the North and Northeast regions, has its productive potential limited by edaphic characteristics and degradation processes of soil physical quality, such as compaction. This process may interfere with plant development and productivity by restricting root system growth, aeration, water and nutrient availability. The objective of this work was to analyze the interference of different levels of compaction in the soil physical characteristics, root growth, development of the aerial part and productivity of cowpea. The experiment was conducted in a greenhouse following a completely randomized design with a control (control) and four levels of soil compaction, with four replications. Each experimental unit was composed of PVC tubes composed of a 0.05-m layer of gravel, cotton fabric and a 0.04-m layer of soil. The different levels of compaction were obtained using a proctor socket and a wooden base. Based on the value of penetration resistance (PR) of 1.00 MPa, soil reached the macroporosity considered as critical theresohold for soil aeration. Results indicate that the higher the PR of the soil, the lower the development of the root system and the aerial part. The productive aspects of cowpea presented better results in plants grown in soils with a level of resistance to penetration close to 0.8 MPa.
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Vásquez-Varela, L. R., and C. Mendoza. "Implications of physical and chemical changes in volcanic ash soils related to road construction." Journal of Physics: Conference Series 2118, no. 1 (November 1, 2021): 012012. http://dx.doi.org/10.1088/1742-6596/2118/1/012012.
Повний текст джерелаАнотація:
Abstract Soils derived from weathered pyroclastic material in a humid tropical environment, known as volcanic ash soils, cover a low portion of the Earth’s surface. However, its unique characteristics, such as high porosity, low unit weight, high water content, and susceptibility to change in properties by drying and remolding, justify its study due to the impact of these characteristics in the construction of embankments and road subgrades, particularly on the compaction characteristics. The urban settlements located in the tropical zone, close to areas of volcanic activity, develop their road infrastructure on this type of soil. Under laboratory conditions, these soils’ chemical and physical changes, particularly on the particle arrangement or fabric, create a gap between their expected and actual behavior at the construction site. This article presents some problems in road construction related to these unique features and how to deal with them on the construction site, applying conventional classification and compaction tests in the lab and construction site. The particularities of the soils in these conditions are explained using unconventional tests to assess the microscopic effects of compaction on the soil fabric.
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STALHAM, M. A., E. J. ALLEN, A. B. ROSENFELD, and F. X. HERRY. "Effects of soil compaction in potato (Solanum tuberosum) crops." Journal of Agricultural Science 145, no. 4 (February 22, 2007): 295–312. http://dx.doi.org/10.1017/s0021859607006867.
Повний текст джерелаАнотація:
SUMMARYSince many soils used for growing potatoes in the UK are likely to be close to their plastic limit for cultivation during early spring, there exists the potential for soil compaction to occur during planting which will restrict root penetration. A series of experiments showed that soil compaction delayed emergence, reduced rate of leaf appearance and ground cover expansion, shortened canopy cover duration and restricted light interception, which combined to reduce tuber yield. Rooting density and maximum depth of rooting were reduced, particularly where compaction was shallow. In some soils, irrigation helped alleviate some of the effects of compaction but in others it exacerbated their severity. Using a cone penetrometer, relationships between rate of root penetration and soil resistance (Ω) were established from a number of experiments and replicated blocks in commercial fields and an overall relationship of the form y=16·3–4·08Ω mm/day was produced. Root penetration rates of c. 20 mm/day were measured in the intensively-cultivated ridge zone but growth rates were halved at a Ω of 1·5 MPa. A survey of 602 commercial fields showed that two thirds of fields had Ωs ⩾3 MPa (where root growth rates would be <2 mm/day) within the top 0·55 m of the soil profile. Thus, rooting depth is likely to be considerably shallower than desirable and lead to inefficiency of water and nutrient utilization. The use of powered cultivators to separate stones and clods from beds or ridges and produce a fine seedbed is now almost universally adopted in the UK. However, the system is both time and energy inefficient and increases the risk of creating soil compaction, particularly at shallow depths. All cultivation equipment has been shown to cause compaction and it is suggested that the consequences of the shortening of the growing season from delaying planting by a few days to allow the soil to dry are far less than the yield and quality losses caused by compaction.
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Salmi, Kristin, Hjalmar Staf, and Per-Lennart Larsson. "On the Relation Between Pressing Energy and Green Strength at Compaction of Hard Metal Powders." Journal of Materials Engineering and Performance 30, no. 4 (March 9, 2021): 2545–51. http://dx.doi.org/10.1007/s11665-021-05588-5.
Повний текст джерелаАнотація:
AbstractThe relation between pressing energy and green strength is examined experimentally and numerically using a commercially available design of experiment (DOE) software, at compaction of five hard metal powder materials. This is of substantial practical importance, in particular at pressing of complicated geometries when high values on the green strength is necessary. The compaction energy is here experimentally determined at uniaxial compaction of a cylindrical die, filled with powder material, by measuring punch force and compression. The corresponding measurements of the resulting green strength are performed using standard three-point bend (3PB) testing. The statistical analysis of the results shows that the relation between the two properties, pressing energy and green strength, is very close to a linear fit with the coefficient of determination R2 taking on the value 0.92. This suggests that the pressing energy is an important quantity for reaching a target value on the green strength and the linear relation is certainly convenient in particular when compaction of similar materials is at issue. In parallel with the experimental work finite element calculations are performed in order to evaluate the effect from friction between the powder and the die wall, and it was found that this feature has a limited effect on the pressing energy when similar materials are at issue and is not detrimental for the usefulness of the present correlation approach.
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Cui, Chun-yu, Shu-jian Wang, Wei Cui, and Xiao Zheng. "Bearing Behavior of the Fly Ash Deposits on Expressway." Advances in Civil Engineering 2019 (July 25, 2019): 1–11. http://dx.doi.org/10.1155/2019/8450401.
Повний текст джерелаАнотація:
The reinforcement treatment for embankment using the fly ash deposits as the filling material for roadbed was clarified in this paper. Studies have shown that fly ash can be used as the filling material for embankment, but the subgrade bearing capacity from the original fly ash deposits cannot meet the requirements for operating. Fly ash has a good condition to run the dynamic consolidation for meeting the requirements of embankment compaction. The modulus of resilience and the California bearing ratio (CBR) of fly ash is close to that of general filling material for embankment. Fly ash also has the engineering properties of high void ratio and low cohesion. The maximum level of compaction of the fly ash deposits can be 93% and the bear capacity can be about twice over before after the treatment.
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Lee, Jong Keuk, Sung Jei Hong, Min Ku Lee, Jung G. Lee, Chang Kyu Rhee, S. J. Jeong, J. S. Park, and J. S. Park. "Fabrication of High Density Y2O3 Ceramics by Magnetic Pulsed Compaction." Solid State Phenomena 119 (January 2007): 175–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.119.175.
Повний текст джерелаАнотація:
Highly dense Y2O3 ceramics have been fabricated by a magnetic pulsed compaction (MPC) which is capable of reaching a sufficiently high pressure (~1GPa) in a very short duration (a few microseconds), and a subsequent pressureless sintering at 1600°C. The Y2O3 green bodies with a relative density of about 68% were achieved by the application of the MPC process due to the effect of an enhanced rearrangement and a high speed movement of the particles, without the help of ceramic binder. Those compacts showed densities greater than 95%, which is very close to the theoretical density, after the subsequent pressureless sintering process at 1600 oC. The shrinkage rates of the diameter for the samples compacted by the MPC process were markedly reduced, when compared to those for the ones by the conventional compaction (CC) process.
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Mahajan, S., and G. C. Berry. "Up Close: Materials Research at Carnegie Mellon." MRS Bulletin 12, no. 1 (February 1987): 27–28. http://dx.doi.org/10.1557/s088376940006872x.
Повний текст джерелаАнотація:
Materials research is a long-standing tradition at Carnegie Mellon. Since its inception as Carnegie Technical Schools in 1906, the metallurgy program has flourished on the campus. Evolving from a single department involved in metals research formed in 1906, leading-edge, interdisciplinary materials research has grown considerably, with materials-related research now carried out in many departments. These include Chemical Engineering, Chemistry, Civil Engineering, Electrical and Computer Engineering (ECE), Mathematics, Mechanical Engineering, Physics, and Mellon Institute (an affiliate of the University), and, of course, Metallurgical Engineering and Materials Science (MEMS). It is beyond the scope of this article to cover every aspect of materials-related research at Carnegie Mellon. Consequently, we have decided to concentrate on materials and topics of particular interest to MRS members.The current research pertaining to materials at Carnegie Mellon can be broadly classified by material type into three categories: metals and alloys, polymers, and electronic and magnetic materials.The major thrust on research in metals and alloys is in MEMS. In addition, there are a number of complementary efforts in Chemical Engineering and Mechanical Engineering. For example, Prof. Sides of Chemical Engineering is evaluating electrolytic extraction of aluminum from its ores, while Professors Prinz, Sinclair, Steif, Swedlow, and Wright of Mechanical Engineering are examining the macroscopic flow behavior of metals and alloys and its relevance in manufacturing engineering. Prof. Prinz is also interested in vibratory compaction of metal powders, both from experimental and modeling points of view.
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Agarwal, Shashi K. "Lifestyles and their Close Relationship with Gastrointestinal Diseases (Part I: Diet)." East African Scholars Journal of Medical Sciences 5, no. 2 (February 18, 2022): 49–57. http://dx.doi.org/10.36349/easms.2022.v05i02.005.
Повний текст джерелаАнотація:
The gastrointestinal tract (GI) is a continuous hollow twisting tube from the mouth to the anus. Its hollow organs include the mouth, esophagus, stomach, small intestine, large intestine, and anus. The liver, pancreas, and gallbladder (solid organs) are also considered part of the GI tract. The principal functions of the GI tract are digestion, absorption, excretion, and protection. Digestion and absorption occur primarily in the stomach and small intestine. Desiccation and compaction of waste occur in the large intestine. The waste products are then stored in the sigmoid colon and rectum before their elimination. The GI tract is influenced by several lifestyles, including the amount and the composition of the diet. The macronutrients and micronutrients in the diet, if prudent, are important for maintaining good GI health. However, unhealthy choices may cause or influence the development of GI pathology (such as esophageal reflux, peptic ulcer, inflammatory bowel disease, dietary intolerance, or even GI cancers). The lifestyle GI connection is reviewed in this two-part manuscript.
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Lebedev, Mikhail S., Marina I. Kozhukhova, and Evgeniy A. Yakovlev. "The Effect of Composition and Fineness of Mineral Fillers on Structure of Asphalt Binder." Materials Science Forum 1017 (January 2021): 81–90. http://dx.doi.org/10.4028/www.scientific.net/msf.1017.81.
Повний текст джерелаАнотація:
Ultra-fine filler or mineral powder is the main mineral component responsible for structure formation in the bitumen-mineral system, therefore mineral and chemical composition, chemical reactivity, surface area, fineness, particle shape, porosity and density are the crucial parameters for structure formation of the composite. This work studied the effect of fineness and chemical and mineral composition of fillers on the structure of asphalt binder. It was demonstrated that an increase in surface area boosts porosity, and void content of the filler, but reduces the porous size. For carbonate fillers such as limestone and chalk with high fineness it was investigated that compaction applied to asphalt binder specimens showed very low water saturation. This can be explained by the film effect of water impermeable bitumen in the matrix and by small porous size with mostly close pores. An increase in surface area of silicate fillers improves the compaction of structure but cannot reach the same level of compaction degree demonstrated by the specimens with carbonate fillers. SEM analysis of microstructural characteristics for the asphalt binder showed that the incorporation of fine-fractioned chalk filler resulted in the formation of asphalt binder with high density and micro-and nanoporous matrix.
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Minde, Mona Wetrhus, and Aksel Hiorth. "Compaction and Fluid—Rock Interaction in Chalk Insight from Modelling and Data at Pore-, Core-, and Field-Scale." Geosciences 10, no. 1 (December 21, 2019): 6. http://dx.doi.org/10.3390/geosciences10010006.
Повний текст джерелаАнотація:
Water weakening is a phenomenon that is observed in high porosity chalk formations. The rock interacts with ions in injected water and additional deformation occurs. This important effect needs to be taken into account when modelling the water flooding of these reservoirs. The models used on field scale are simple and only model the effect as a change in water saturation. In this paper, we argue that the water weakening effect can to a large extend be understood as a combination of changes in water activity, surface charge and chemical dissolution. We apply the de Waal model to analyse compaction experiments, and to extract the additional deformation induced by the chemical interaction between the injected water and the rock. The chemical changes are studied on a field scale using potential flow models. On a field scale, we show that the dissolution/precipitation mechanisms studied in the lab will propagate at a much lower speed and mainly affect compaction near the well region and close to the temperature front. Changes in surface charge travel much faster in the reservoir and might be an important contributor to the observed water weakening effect. We also discuss how mineralogical variations impacts compaction.
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Lebedev, Mikhail S., Marina I. Kozhukhova, and Evgeniy A. Yakovlev. "The Effect of Composition and Fineness of Mineral Fillers on Structure of Asphalt Binder." Materials Science Forum 1017 (January 2021): 81–90. http://dx.doi.org/10.4028/www.scientific.net/msf.1017.81.
Повний текст джерелаАнотація:
Ultra-fine filler or mineral powder is the main mineral component responsible for structure formation in the bitumen-mineral system, therefore mineral and chemical composition, chemical reactivity, surface area, fineness, particle shape, porosity and density are the crucial parameters for structure formation of the composite. This work studied the effect of fineness and chemical and mineral composition of fillers on the structure of asphalt binder. It was demonstrated that an increase in surface area boosts porosity, and void content of the filler, but reduces the porous size. For carbonate fillers such as limestone and chalk with high fineness it was investigated that compaction applied to asphalt binder specimens showed very low water saturation. This can be explained by the film effect of water impermeable bitumen in the matrix and by small porous size with mostly close pores. An increase in surface area of silicate fillers improves the compaction of structure but cannot reach the same level of compaction degree demonstrated by the specimens with carbonate fillers. SEM analysis of microstructural characteristics for the asphalt binder showed that the incorporation of fine-fractioned chalk filler resulted in the formation of asphalt binder with high density and micro-and nanoporous matrix.
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Effendi, Mahmud Kori, Novi Rahmayanti, and Ilman Fathurahman. "Parametric Study of Self Compacting Concrete Beams Using Finite Element Nonlinear Analysis." MEDIA KOMUNIKASI TEKNIK SIPIL 27, no. 2 (December 30, 2021): 213–20. http://dx.doi.org/10.14710/mkts.v27i2.36507.
Повний текст джерелаАнотація:
Self-compacting concrete has self-flowing, viscous and compact properties that minimize mechanical compaction. This concrete is suitable for solving the concrete pouring in the narrow and congested reinforcement. Beams made of both self-compacting concrete and normal high-strength concrete are analyzed by MSC Marc / Mentat software. Steel is modeled by being embedded in concrete. The failure criterion of Linear Mohr-Coulomb is used for concrete and Von Mises for reinforcing steel, respectively. Concrete and the plate support are modelled by 3D solid elements. For the steel, the truss element is used. The contact analysis is implemented between beam and both steel plate and steel supports. The load-deflection curve for both concrete are almost the same as the results of the experimental curve. The results of the contact analysis also showed that there were contact and separation in the contact area. The shear retention factor value close to one meaning will restrain greater loads. The results of the study on the reinforcement ratio also showed a reduction of 70% and an increase of 70% when using minimum and maximum reinforcement, respectively. The larger concrete cover also reduces the load that the beams can restrain.
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Vogeler, Iris, Rogerio Cichota, Siva Sivakumaran, Markus Deurer, and Ian McIvor. "Soil assessment of apple orchards under conventional and organic management." Soil Research 44, no. 8 (2006): 745. http://dx.doi.org/10.1071/sr06096.
Повний текст джерелаАнотація:
To determine the effect of wheel traffic and two different management practices on soil compaction and its consequences on physical and chemical soil properties, we measured penetration resistance, water infiltration, bulk density, macroporosity, chemical mobility, air permeability, and soil strength in a conventional orchard (integrated fruit-production program) with bare (sprayed with herbicides) rows and an organic apple orchard with grassed rows. Resistance measurements were taken both within the tree row and the wheel track, down to a depth of 0.35 to 0.40 m. The results indicate that compaction is greater in the wheel tracks under both management methods. Compaction in the wheel track was higher under organic than conventional management. Organic management resulted in a higher macroporosity in both the row and the wheel-track than conventional management. The ‘close-to-saturation’ infiltration rate was significantly greater within the row of the organic orchard (0.06 m/h) compared with the row of the conventional orchard (0.02 m/h), and compared with the wheel tracks (0.01 m/h). The precompression stress value in the top 100 mm, a measure of the soil strength, was low on all sites. The chemical mobilities were 57 and 50% in the organic orchard, and 86 and 93% in the conventional orchard, respectively, for wheel track and row. Apart from the compaction in the wheel track of the organic orchard, physical and chemical soil characteristics were in a better condition compared with the conventional orchard.
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ELIAS, ANDRÉIA REGINA DIAS, LUIZ FERNANDO DE ROS, and ANA MARIA PIMENTEL MIZUSAKI. "Padrões Diagenéticos em Arenitos de Sistemas de Sabkha Costeiros-Eólicos: Um Estudo Comparativo dos Reservatórios Juruá da Área de Urucu, Bacia do Solimões, AM." Pesquisas em Geociências 31, no. 1 (June 30, 2004): 51. http://dx.doi.org/10.22456/1807-9806.19567.
Повний текст джерелаАнотація:
Coastal-eolian sabkha sandstones from different ages and basins show similar diagenetic patterns, which understanding is important for their evaluation as geochemical systems and as hydrocarbon reservoirs. The Carboniferous sandstones of the Juruá Formation (Solimões Basin) are one of the most important gas reservoirs of Brazil. The sandstones and interbedded mudrocks, evaporites and dolostones were deposited within a coastal sabkha environment with pervasive eolian reworking, under increasing marine influence, and hot and dry climate. Four stacked drying/wetting upward cycles were identified, with sabkha facies in the base overlain by eolian deposits, followed again by sabkha deposits, commonly eroded by the next cycle. Eolian dune and sandsheet sandstones are the best reservoirs. The diagenetic evolution and the relationships among diagenesis, depositional facies and stratigraphic unit boundaries show similarities with other coastal-eolian sabkha sandstones. The eodiagenesis is characterized by mechanical compaction, hematite and infiltrated clay coatings, framboidal pyrite, microcrystalline and blocky dolomite. Mesodiagenesis comprises chemical compaction, K-feldspar and quartz overgrowths, poikilotopic anhydrite, feldspar dissolution and albitization, illite and chlorite authigenesis, and late quartz, Fedolomite/ ankerite, calcite and siderite. Localized telogenetic effects include oxidation of ferroan constituents and kaolinite precipitation. Blocky dolomite and quartz cementation, and chemical compaction through intergranular and stylolitic pressure dissolution are more abundant in the non-eolian sandstones. Microcrystalline pore-filling and pore-lining dolomite, and patchy, poikilotopic, post-compactional anhydrite cementation, mostly close to the contacts with interbedded evaporites, are more abundant in the eolian sandstones. These diagenetic patterns are similar to those of the Rotliegend Group in northern Germany and in the North Sea, of the Norphlet and Tensleep Formations in USA, of the Muschelkalk Formation in Spain, and of the Monte Alegre Formation from the Amazonas Basin, northern Brazil. The similarities among the diagenetic histories of these coastal-eolian sabkha sandstones are ascribed to their similar patterns of stratigraphic organization (intercalated evaporite and carbonate beds) and of composition and circulation of pore fluids.
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Bjørlykke, K. "Clay mineral diagenesis in sedimentary basins — a key to the prediction of rock properties. Examples from the North Sea Basin." Clay Minerals 33, no. 1 (March 1998): 15–34. http://dx.doi.org/10.1180/000985598545390.
Повний текст джерелаАнотація:
AbstractDissolution of feldspar and mica and precipitation of kaolinite require a through flow of meteoric water to remove cations such as Na+ and K+ and silica. Compaction driven pore-water flow is in most cases too slow to be significant in terms of transport of solids. The very low solubility of A1 suggests that precipitation of new authigenic clay minerals requires unstable Al-bearing precursor minerals. Chlorite may form diagenetically from smectite and from kaolinite when a source of Fe and Mg is present. In the North Sea Basin, the main phase of illite precipitation reducing the quality of Jurassic reservoirs occurs at depths close to 4 km (130-140°C) but the amount of illite depends on the presence of both kaolinite and K-feldspar. Clay mineral reactions in shales and sandstones are very important factors determining mechanical and chemical compaction and are thus critical for realistic basin modelling.
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Sharma, Purva, Yash Jobanputra, Robert Chait, and Waqas Ghumman. "Acute-onset heart failure secondary to biventricular non-compaction cardiomyopathy and atrial septal defect in a woman presenting in the seventh decade." BMJ Case Reports 15, no. 2 (February 2022): e246385. http://dx.doi.org/10.1136/bcr-2021-246385.
Повний текст джерелаАнотація:
We present a case of a previously asymptomatic 63-year-old woman who presented with worsening dyspnoea for 3 weeks. Initial transthoracic and later transoesophageal echocardiography confirmed biventricular non-compaction cardiomyopathy and a large secundum atrial septal defect (ASD) measuring 1.4 cm. Additionally, there was a haemodynamically significant left to right shunt causing acute decompensated systolic heart failure. She eventually underwent closure of the septal defect using a AMPLATZER Septal Occluder device. Decision to close the defect was made as the left to right shunt was causing severe pulmonary hypertension and acute heart failure. Since most heart failure treatments involve lowering of the LV afterload there was consideration that this could cause right to left shunting and could cause an Eisenmenger physiology. Hence the AMPLATZER Septal Occluder device was placed to eliminate the shunt through the ASD. The ASD combined with the non-compaction posed significant treatment challenge in this case.
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Mallick, Rajib B., Shane Buchanan, E. Ray Brown, and Mike Huner. "Evaluation of Superpave Gyratory Compaction of Hot Mix Asphalt." Transportation Research Record: Journal of the Transportation Research Board 1638, no. 1 (January 1998): 111–19. http://dx.doi.org/10.3141/1638-13.
Повний текст джерелаАнотація:
The effect of restricted zone on volumetric properties of mixes consisting of all crushed, and all crushed and partially uncrushed, materials was evaluated. For a given aggregate blend, gradations below or above the restricted zone provided higher voids in mineral aggregate (VMA) than mixes through the restricted zone. Mixes with crushed aggregate provided higher VMA than mixes with partially crushed aggregate. It is recommended that further work be conducted to evaluate the effect of different types and shapes of aggregates on the volumetric properties of specimens compacted with the Superpave gyratory compactor. According to the current Superpave mix design system, the bulk specific gravity of a compacted specimen at any gyration is back calculated from the bulk specific gravity determined at Nmaximum and a correction factor determined at Nmaximum. This procedure assumes that the correction factor is constant at all gyrations. A part of this study was carried out to compare the correction factors obtained at different gyration levels during compaction of hot mix asphalt and to evaluate the change in correction factor with gyration levels. Specimens were compacted at different gyration levels, and the bulk specific gravity of each was determined at each gyration level. Bulk specific gravities at each of the gyration levels were also obtained by back calculation from bulk specific gravity at Nmaximum. The correction factor was found to decrease and become close to constant at higher gyration levels. At lower gyrations, densities were found to be greater than those obtained by back calculation. It is recommended that mixes be compacted to Ndesign for determination of design asphalt content.
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Klaus, Angela V., and W. Steven Ward. "Investigation Of Dna Organization In Spermatozoa Using High Resolution Scanning Electron Microscopy." Microscopy and Microanalysis 5, S2 (August 1999): 1282–83. http://dx.doi.org/10.1017/s1431927600019735.
Повний текст джерелаАнотація:
The average somatic nucleus is only 10 microns in diameter, yet contains 2 meters of DNA coiled within its volume. This compaction must be accomplished in such a way so that the DNA remains accessible to the machinery of transcription, replication and repair. Sperm nuclei also have compacted DNA; however, structurally and functionally the arrangement of DNA in sperm is vastly different from that of somatic DNA. Somatic DNA is initially compacted by coiling around histone octamers, while sperm DNA is bound to elongate, highly basic proteins called protamines. Protamines bind the major groove of the double helix and allow adjacent DNA strands to come in close contact by neutralizing the negative charge of the sugar-phosphate backbone. Figure 1 illustrates the two most widely accepted models of DNA compaction in both somatic and sperm nuclei.The arrangement of DNA within sperm nuclei is difficult to study because it is so highly compressed.
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Rodrigues, Daniel, Gilberto Vicente Concílio, Jose Adilson de Castro, and Marcos Flavio de Campos. "Effect of Compaction Pressure on the Hysteresis Loop of NdFeB Bonded Magnets." Materials Science Forum 899 (July 2017): 576–80. http://dx.doi.org/10.4028/www.scientific.net/msf.899.576.
Повний текст джерелаАнотація:
Compression moulded NdFeB bonded magnets can advantageously replace the sintered version in applications that require specific shape and size. The maximum densities that can be obtained for ready-to-press commercial raw materials are close to 6.0 g/cm3. For large pieces, uniaxially pressed, densities should be limited to values as 5.0 g/cm3 due to the friction during compression. This paper investigate the effects of final density (ranging from 5.0 to 6.0 g/cm3) on the magnetic of compression moulded magnets. A ready-to-press Magnequench MQPB+ was used as raw material. Small cylindrical samples were produced by press and cure. Results are presented and discussed considering aspects related to relative densities. The magnetic properties are dependent of density, and coercivity decreases with deformation during compaction.
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MacFerrin, Michael J., C. Max Stevens, Baptiste Vandecrux, Edwin D. Waddington, and Waleed Abdalati. "The Greenland Firn Compaction Verification and Reconnaissance (FirnCover) dataset, 2013–2019." Earth System Science Data 14, no. 2 (March 1, 2022): 955–71. http://dx.doi.org/10.5194/essd-14-955-2022.
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Abstract. Assessing changes in the density of snow and firn is vital to convert volume changes into mass changes on glaciers and ice sheets. Firn models simulate this process but typically rely upon steady-state assumptions and geographically and temporally limited sets of field measurements for validation. Given rapid changes recently observed in Greenland's surface mass balance, a contemporary dataset measuring firn compaction in a range of climate zones across the Greenland ice sheet's accumulation zone is needed. To fill this need, the Firn Compaction Verification and Reconnaissance (FirnCover) dataset comprises daily measurements from 48 strainmeters installed in boreholes at eight sites on the Greenland ice sheet between 2013 and 2019. The dataset also includes daily records of 2 m air temperature, snow height, and firn temperature from each station. The majority of the FirnCover stations were installed in close proximity to automated weather stations that measure a wider suite of meteorological measurements, allowing the user access to auxiliary datasets for model validation studies using FirnCover data. The dataset can be found here: https://doi.org/10.18739/A25X25D7M (MacFerrin et al., 2021).
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Rudenko, N. E., E. V. Kulaev, V. N. Rudenko, and A. V. Seminskij. "Multifunctional coulter of a tilled seeding-machine." Traktory i sel hozmashiny 85, no. 4 (August 15, 2018): 26–30. http://dx.doi.org/10.17816/0321-4443-66378.
Повний текст джерелаАнотація:
Coulters are installed for cutting sowing grooves on the seeding-machines. The most common are disk, keeled, razor-shaped, rocker coulters. The disadvantage of disc and razor-shaped coulters is the formation of the unsealed bottom of the sowing groove, which contradicts the agrotechnical requirements. According to the recommendations, pre-sowing soil cultivation should be conducted no later than a day before sowing. However, it is practically impossible to sustain this over the whole area. Weeds appear at the period between the presowing treatment and sowing. According to the known data of Russian and foreign scientists, if, for example, weeds are not removed in tomato crops in the first 10 days, yields are reduced to 50 %. Therefore, the coulter must be equipped with a weed plow. The seed bud must penetrate as soon as possible into the lower layers of the soil and provide seed buds with water and nutrition. This task is solved by slicing when sowing the underseed gap. The field germination is ensured by close contact of the seed with the soil. Now this is achieved by installing a rolling compactor behind the coulters. However, surface compaction of the soil makes it difficult for seedlings to leave the day surface. In addition, moisture is pulled up and the weed seeds located in the upper layer, where the soil temperature is higher, grow quickly. We do not need a soil compactor, but an action directly on the seeds, ensuring their close contact with the soil. A multifunctional coulter, that has a share with 80 mm-wide shank, which is able to make seed drill of 25 mm width, a spring bar slitter for slicing underseed slit and a 3 mm diameter rod seal to ensure seed contact with the soil, was developed. Descending from the column dry soil covers groove with a thin 15...20 mm layer.
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Xu, Tianyue, Ruxin Zhang, Yang Wang, Xinming Jiang, Weizhi Feng, and Jingli Wang. "Simulation and Analysis of the Working Process of Soil Covering and Compacting of Precision Seeding Units Based on the Coupling Model of DEM with MBD." Processes 10, no. 6 (June 1, 2022): 1103. http://dx.doi.org/10.3390/pr10061103.
Повний текст джерелаАнотація:
In precision seeding, the final displacements of the seeds are determined as a working result of the profiling mechanism, opener, seed-metering device, covering apparatus and compacting machine. For a better understanding of the disturbance of seed displacement during soil covering and compaction in the actual working process, experiments and simulations have been performed. In this paper, a type of soybean seeding monomer was taken as the research object, and a soil bin test of soil covering and compacting was executed. The experimental results showed that the traction velocity and the open angle of the covering discs had a significant influence on the changes in the horizontal and vertical displacements of seeds during the soil covering processing. With an increasing traction velocity, the vertical displacements of seeds increased after soil covering; in contrast, the horizontal displacements decreased. When the covering apparatus had a larger open angle it had a smaller disturbance influence on the soil. Therefore, with an increase in the opening angle, the changes in the vertical and horizontal displacements of seeds showed a decreasing trend. Inversely, in the process of compacting, the forward velocity had little effect on the three-dimensional displacement change in the seeds after compacting. The analysis model of the precision seeding unit was established based on the coupling model of the DEM (discrete element method) with MBDs (multi-body dynamics). The process of soil covering and compacting was simulated and analyzed. The comparison between the experimental results and the simulated results showed that the trend was similar, and the two results were close. Thus, the feasibility and applicability of the coupling method were verified. It also provided a new method for the design and optimization of covering and compacting components of a precise seeding monomer.
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Cai, Jiannan, Qingyi Gao, Hyonho Chun, Hubo Cai, and Tommy Nantung. "Spatial Autocorrelation in Soil Compaction and Its Impact on Earthwork Acceptance Testing." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 1 (January 2019): 332–42. http://dx.doi.org/10.1177/0361198118822279.
Повний текст джерелаАнотація:
The compaction quality of soil embankments is critical to the long-term performance of the pavements placed on them. In current quality assurance (QA) practice, state highway agencies (SHAs) rely on in-situ testing at a small number of point locations to decide whether to accept or reject the product, assuming that the samples taken at random locations are independent of each other. This assumption, however, is invalid because soil properties are spatially autocorrelated – the properties at nearby locations are correlated to each other. Consequently, if the sampling locations are close to each other, the effective number of samples is reduced, which in turn increases the risk of incorrect accept/reject decisions. This study addressed this spatial autocorrelation issue in soil acceptance testing. Soil data from the U.S Highway 31 project, collected by intelligent compaction (IC) in the format of compaction meter value (CMV), were used to prove the existence of spatial autocorrelation using the semivariogram and Moran’s I analysis. The impact of spatial autocorrelation on soil acceptance testing was assessed by comparing the testing power under two scenarios (with and without spatial autocorrelation). The results suggest that the existence of spatial autocorrelation decreases the testing power, resulting in a greater risk to the SHA. Based on these findings, this study proposed two spatial indices to mitigate the negative impact of spatial autocorrelation by controlling the spatial pattern of random samples. A web tool was also developed as an implementation to augment the random sampling process in field QA practice by incorporating the spatial pattern of samples.
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Shawn Smith, Steven, and Ilya Tsvankin. "Modeling and analysis of compaction-induced traveltime shifts for multicomponent seismic data." GEOPHYSICS 77, no. 6 (November 1, 2012): T221—T237. http://dx.doi.org/10.1190/geo2011-0332.1.
Повний текст джерелаАнотація:
Modeling of time shifts associated with time-lapse (4D) seismic surveys is helpful in evaluating reservoir depressurization and inverting for subsurface stress. Using coupled geomechanical and full-waveform seismic modeling, we study the influence of compaction-induced stress and strain around a simplified reservoir on compressional (P), shear (S), and mode-converted (PS) waves. We estimate compaction-induced time shifts and analyze their dependence on reflector depth and pressure drop inside the reservoir. Time shifts between synthetic baseline and monitor surveys are obtained by processing techniques that are potentially applicable to field data. Although P-wave time-shift lags for reflectors in the overburden are indicative of induced anisotropy, they are two to three times smaller than S-wave time-shift leads for reflectors beneath the reservoir. We also investigate the contributions of the deviatoric and volumetric stains to the time shifts for all three modes. Time shifts for S- and PS-waves are strongly influenced by elevated volumetric and deviatoric strains inside the reservoir. Almost constant S-wave time shifts for a range of offsets and source locations indicate that the contribution of stress-induced velocity anisotropy to shear-wave signatures is weak because the symmetry is close to elliptical. Our modeling also shows that mild tilt of a rectangular reservoir, or its replacement with an elliptically shaped reservoir of the same aspect ratio, has little influence on time shifts. Potentially, the developed methodology can be applied to estimate compaction-induced stress fields using simple compartmentalized reservoir models.