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1
Polanen, Tim van. « Snak, Claas and Bastiaan’s Struggle for Freedom ». BMGN - Low Countries Historical Review 136, no 1 (30 mars 2021) : 33–58. http://dx.doi.org/10.18352/bmgn-lchr.10746.
Texte intégralRésumé :
In the Dutch Republic slavery was not permitted on its soil in Western Europe. Enslaved people obtained their freedom by setting foot on Dutch soil. In 1776, the scope of this free soil principle was limited by a statute of the States General. From this moment onwards only slaves who remained in the Republic for longer than six months would automatically become free. In the literature, it was hitherto assumed that with the establishment of this statute the first debates about the scope of the free soil principle were initiated. This article demonstrates that this assumption is false. Previously, two court cases from 1735 and 1736, between two enslaved men from Curaçao and their masters, had already given rise to discussion. During these court cases, lawyers and judges elaborately debated the boundaries of the free soil principle. Did every enslaved person automatically obtain their freedom, or was, for instance, the permission of the master required to travel to the Dutch Republic? The two court cases give insight into what contemporaries thought about the free soil principle, thus shedding new light on the States General’s statute of 1776.
2
Ahn, Seongnoh, Gun Park, Hyungchul Yoon, Jae-Hyeok Han et Jongwon Jung. « Evaluation of Soil–Structure Interaction in Structure Models via Shaking Table Test ». Sustainability 13, no 9 (29 avril 2021) : 4995. http://dx.doi.org/10.3390/su13094995.
Texte intégralRésumé :
Modeling the soil–structure interaction (SSI) in seismic design involves the use of soil response curves for single-degree-of-freedom (SDOF) structures; however, real structures have multiple degrees of freedom (MDOF). In this study, shaking-table-derived p-y curves for SDOF and MDOF superstructures were compared using numerical analysis. It was found that an MDOF structure experienced less displacement than an SDOF structure of the same weight, but the effect of increasing the DOF decreased at greater pile depths. Numerical analysis results estimated using the natural periods and mass participation rates of the structures were similar to those of shaking table tests. Abbreviations: finite element: FE; frequency response function: FRF; multiple degrees of freedom: MDOF; single degree of freedom: SDOF; soil–structure interaction: SSI.
3
Min, Kyung-Kuk. « Why John Rawls’Theory of Liberty Neglected Economic Freedom ». Korea Public Choice Association 2, no 1 (30 mars 2023) : 33–55. http://dx.doi.org/10.55795/jpc.2023.2.1.033.
Texte intégralRésumé :
Even those who value political and civil liberties tend to ignore, or at least downplay, economic liberties. Among the modern philosophers who represent such a trend, the representative figure is John Rawls. He neglected the freedom to own the means of production and the freedom to contract as essential freedoms of a market society, on the grounds that they could not be conditions for developing and exercising “moral capacities”. In the just world he envisioned, extensive economic freedom is not allowed.
The purpose of this article is to show, firstly, that severe restrictions on economic freedom endanger civil and political liberties as an institutional condition for the development of a sense of justice, on the ground that economic freedom is the bulwark of all freedoms, and especially that it is the soil of democracy. Secondly, a market society is by no means a society in which people act out of narrow-minded selfishness. People depend on each other to live. Equal freedom is what makes human interdependence possible. Only those who maintain the beneficial bonds of interdependence can succeed in the marketplace. Productive interdependence, facilitated by voluntary associations independent of politics, such as family, public life, moral, religious and business associations, is the source of innovation and entrepreneurship.
When Rawls deliberately excluded economic rights from his basic rights list, the intellectual basis toward counter-free society were well settled, through which liberal-leftist redistribution became possible virtually with no limit.
4
Sudarsono, Untung, et G. Hasibuan. « Engineering Geological Characteristics of the Residual Soil, Lower Quaternary Sediments in Kertajati Region, Majalengka, West Java ». Indonesian Journal on Geoscience 6, no 3 (28 septembre 2011) : 177–89. http://dx.doi.org/10.17014/ijog.6.3.177-189.
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DOI: 10.17014/ijog.v6i3.125Only few engineering geological researches on residual soil have been conducted in Indonesia, whereas many infrastructure projects take place on undulating area and mountainous area which are composed of residual soils. The paper discusses residual soil characteristics of the Lower Quaternary sediment (Qos) in Kertajati area, Majalengka. The methodology of the research consists of engineering geological mapping, in situ test using 2.5 ton penetrometer, sampling and laboratory test for index properties, Atterberg limits, grain size analysis, and strength tests. Field test analysis data show that the thickness of residual soil resting on the basement rock in the study area varies from 2.40 - 14.20 m. Upwards, it comprises sands, silts, and clays, respectively. Laboratory analysis data indicate that the residual soil is dominated by fine-grained fraction, composed of high plastic clay (CH). Relationship among engineering geological parameters was analysed using linear regression and tested using statistic method t-test to find real correlation among variables within 95 - 90% significance level.. Based on the test, there are real positive correlation with 19 degree of freedom and 5% and 10% level of significance are found in between plasticity indexes (IP) and liquid limits (LL), between plasticity indexes (IP) and clay contents (C), between specific gravities (G ) and clay contents (C). The real negative correlation with nine degree of freedom and 5% and 10% level of significance occurs in between cohesion (c) dengan friction angle (φ). Corelation between degree of saturation (G ) and clay contents (C) with 19 degree of freedom is found in 10% level of significance.
5
Gracheva, R. G. « Genetic and substantive soil classifications and their applicability in geobotanical research ». Plant Biology and Horticulture : theory, innovation, no 149 (10 décembre 2019) : 55–64. http://dx.doi.org/10.36305/0201-7997-2019-149-55-64.
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The first soil classifications dividing soils according to their individual properties and reflecting the resource value of soils were, in fact, substantive classifications. The appearance of soil science that studies soils as special natural bodies changing in space according to natural laws has led to the emergence of genetic soil classifications. The most detailed multilevel Classification of soils of the USSR (1977) is ecological genetic classification based on the relationship between soils and soil formation conditions, where the type of vegetation cover is the top hierarchy level. With the development of soil science, inconsistencies between the genetic classification and the growing volume of knowledge, difficulties in its formalization, and contradictions with the zonal approach have appeared. A paradigm of substantive classification has emerged based on modern measurable morphological and analytical indicators of soils. It is most fully implemented in the World reference base for soil resources (WRB); a compromise option is the substantive- genetic Soil Classification of Russia (2004). In these classifications, for the first time soils with strong human influence (Antrosols and Technosols) are included at a high classification level. The tasks of substantive classifications are the certainty of soil identification; however, discrete classification cells with tight boundaries do not correspond to the continual nature of soils. When using WRB 2014, geobotanical studies receive a certain “freedom” from soils, at the same time, the rigid framework of the parameters of soil properties makes it possible to more accurately identify soil-depended condition of the vegetation cover.
6
Wang, Feng, Xin Le Li et Ting Hua Yi. « Energy Response Spectra of Single-Mass Bi-Degrees of Freedom Systems for Hard Soil Site ». Advanced Materials Research 594-597 (novembre 2012) : 1620–23. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1620.
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The traditional energy response spectra depend on the single-directional earthquake excitations and two dimensional dynamic analyses, in which the imbalance and coupled characteristics of multi-dimensional responses of structures are not considered. So, the energy spectra of constant ductility facotors are developed by considering the single-mass bi-degrees of freedom systems subjected to perpendicular bi-directional earthquake motions. The restoring force rule of single-mass bi-degrees of freedom systems is assumed as two dimensional yield-surface plasticity function. The relative energy spectra for input energy, hysteretic energy, kinetic energy and damping energy are presented and analyzed based on 34 pair earthquake motion records of hard soil site. Analytic results show that the energy spectra for hard soil site have their own characteristics, and the spectral forms and values are affected strongly by vibration period, ductility factor and period ratio of single-mass bi-degrees of freedom systems.
7
Ganjavi, Behnoud, Hong Hao et Iman Hajirasouliha. « Influence of Higher Modes on Strength and Ductility Demands of Soil–Structure Systems ». Journal of Earthquake and Tsunami 10, no 04 (octobre 2016) : 1650006. http://dx.doi.org/10.1142/s1793431116500068.
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Due to the inherent complexity, the common approach in analyzing nonlinear response of structures with soil–structure interaction (SSI) in current seismic provisions is based on equivalent Single Degree-of-Freedom systems (E-SDOF). This paper aims to study the influence of higher modes on the seismic response of SSI systems by performing intensive parametric analyses on more than 6400 linear and non-linear Multi Degree-of-Freedom (MDOF) and E-SDOF systems subjected to 21 earthquake records. An established soil-shallow foundation-structure model with equivalent linear soil behavior and nonlinear superstructure has been utilized using the concept of cone models. The lateral strength and ductility demands of MDOF soil–structure systems with different number of stories, structure-to-soil stiffness ratio, aspect ratio and level of inelasticity are compared to those of E-SDOF systems. The results indicate that using the common E-SDOF soil–structure systems for estimating the strength and ductility demands of medium and slender MDOF structures can lead to very un-conservative results when SSI effect is significant. This implies the significance of higher mode effects for soil–structure systems in comparison with fixed-based structures, which is more pronounced for the cases of elastic and low level of inelasticity.
8
B R Shilpa, Dr G Narayana, Dr B K Narendra. « The Behaviour of Building Frames on Raft Foundation using Dynamic Analysis ». Tuijin Jishu/Journal of Propulsion Technology 44, no 6 (20 janvier 2024) : 4008–17. http://dx.doi.org/10.52783/tjjpt.v44.i6.4362.
Texte intégralRésumé :
When designing building frames for seismic reasons, the effect of soil flexibility is typically disregarded, and the design is executed using the outcomes of dynamic analysis with a fixed base condition. Because the overall lateral stiffness of the structure decreases as a result of soil flexibility, the lateral natural period lengthens. The building frames situated on the Raft foundation may experience a significant change in seismic response due to this extension of the lateral natural period (T). Therefore, it is imperative to consider the soil's flexibility, also known as soil structure interaction, when doing analysis on the foundation's supporting layer.
This paper examines how asymmetric building frames with raft footings behave dynamically when subjected to seismic forces that involve soil-structure interaction. The analysis is performed with SAP 2000*V21 FEM software. The structure is idealized as a three-dimensional space frame, with slabs modeled as a thin shell with four noded plate elements and six degrees of freedom at each node, and beams and columns modeled as two noded line elements. The soil is represented as equivalent springs with one (Winkler) and six (Modified Winkler) degrees of freedom; the stiffness of these springs varies depending on the type of soil and is determined by its dynamic shear modulus and poissons ratio. The Modified Winkler and Winkler raft foundations are modeled as thin shells with four noded plate elements, each with six degrees of freedom, and are criticized so that the element aspect ratios are equal to one.
To assess the impact of soil structure interaction on building frames, the response is compared for a range of building frames with and without consideration of soil flexibility in terms of fundamental Natural Period, Seismic Base Shear, and Max. Lateral Displacement. The parametric study for Zone V takes into account the influence of various parameters, including the number of bays, stories, span lengths, and soil types (i.e., soft, medium, and stiff).
It is discovered that the fundamental lateral natural period and seismic base shear of the system are significantly altered by the influence of soil flexibility on building frames. As soil stiffness decreases, the lateral natural period and seismic base shear increase as a result of soil flexibility. Additionally, it has been noted that as the number of bays increases, so do the building's base shear and lateral period. As the number of bays and stories increases, so does the maximum lateral displacement.
9
Jiang, Kai Yu, Jing Cao, Lei Peng et Ming Ming Chen. « The Deformation Character of Retaining Wall under Horizontal Earthquake ». Applied Mechanics and Materials 152-154 (janvier 2012) : 1443–47. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1443.
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The soil pressure can be influenced by the deformation of retaining wall because of the interaction of wall and soil. The dynamic soil pressure and plastic bottom displacement induced by earthquake action will subsequently result the deformation of the wall. The dynamic soil pressure will vary with the wall deformation and, on the other hand, change the deformation of the wall. The wall under lateral earthquake is assumed to be a single freedom system, thus only one deformation mode is considered in this paper. Based on this assumption, the differential equation of wall-soil dynamic interaction system is proposed.
10
Wang, Zan Zhi, et Lin Yan Jiang. « Free-Field Surface Ground Motion Properties of Stratified Soils ». Advanced Materials Research 243-249 (mai 2011) : 3893–98. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3893.
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In earthquake engineering, the conventional wave motion analyses usually took the subsoil as only one layered soil, and treated the subsoil by using a single freedom system model. Moreover, these methods were often adopted in time domain. In fact, the subsoil are usually stratified due to its forming in different ages, so there exist multiple interfaces which leads to multiple repeated tracings of reflecting and refracting waves in time domain analysis. To avoid the difficulties, a frequency domain analysis method is carried out for linear soil system in this paper, which allows combining all the upward waves and downward waves to a single upward wave and a single downward wave, respectively, and therefore raises great efficiency. The stochastic response analysis of the displacement of layered soils is then performed. The result indicates that, there exists the essential difference in power spectral density (PSD) between stratified soils and single-layer soil, the former has multiple peak values, while the later has only one peak value, and stratified soils have strong filtering effect in high frequency ranges, which can be considered as a low-pass filter.
11
Du, DS, SG Wang, WQ Liu, S. Shi, CP Lee et Jun Xu. « Modal property of base-isolated high-rise structure considering soil–structure interaction effect ». Advances in Mechanical Engineering 10, no 12 (décembre 2018) : 168781401880380. http://dx.doi.org/10.1177/1687814018803808.
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A simplified methodology is rigorously studied in this article to analyze the modal properties of base-isolated high-rise structures with dynamic soil–structure interaction being considered. The proposed methodology is developed based on a more reasonable 2-degree-of-freedom model and the existing simplified methodology which is only applicable for non-isolated structures. The base-isolated structure model with 2 degrees of freedom is supported by swaying and rocking springs and by the corresponding dashpots. Rigorous mathematical derivation is performed, and closed-form formulas of natural periods, modes, and modal damping ratios are derived. Furthermore, the overall accuracy of the proposed methodology was checked against the results of the rigorously derived complex eigenvalue approach proposed by Constantinou and Kneifati. A parametric study is also conducted on the soil–structure interaction effects of base-isolated structures, which indicates that tall and slender structures with stiff isolation systems are more affected by soil–structure interaction effects in comparison to flexible superstructures. The proposed method provides a feasible way to evaluate the soil–structure interaction effects of base-isolated structures efficiently during the schematic design phase.
12
Moustafa, Kamal A. F., et M. El-Gebeily. « Free Vibration Characteristics of Structures With Nonlinear Underlying Soil ». Journal of Vibration and Acoustics 113, no 1 (1 janvier 1991) : 95–99. http://dx.doi.org/10.1115/1.2930161.
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Free vibration of structures is investigated by using a multidegree of freedom nonlinear model that allows for nonlinear behavior of the soil underlying the structure. The considered nonlinearity is due to the dependence of the soil shear modulus on vibration levels. The soil-structure interaction is modelled as nonlinear complex stiffness. The analysis is carried out by using mathematical perturbation theory. Modifications in the natural frequencies and existence of harmonics are demonstrated. The results are applied to an application example of massive deep water gravity structure.
13
Chen, Cheng-Hsing, et Shuh-Hua Yang. « Use of Simple Model to Predict the Forced Vibration Responses of Hualien Model Structure ». Journal of Mechanics 15, no 3 (septembre 1999) : 117–26. http://dx.doi.org/10.1017/s172771910000040x.
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AbstractThis paper uses a simple model, the lumped single-degree-of-freedom system on rigid mat foundation, to investigate the effects of soil-structure interaction on the dynamic response of a soil-structure system. Based on that, the key parameters affecting the natural frequency of a soil-structure system can be easily identified and be used to assess the effects of soil-structure interaction. Accordingly, it was used to simulate the dynamic response of the forced vibration tests conducted at Hualien, Taiwan. Results obtained show that the simple model can predict the field responses very satisfactorily.
14
Sule, Ibrahim. « From Freedom of Expression to Freedom of Speech – the Guarantees under the Nigerian Constitution and the Real Challenges ». American Journal of Law 4, no 1 (2 octobre 2022) : 50–57. http://dx.doi.org/10.47672/ajl.1207.
Texte intégralRésumé :
Right to freedom of expression is one of the globally recognized fundamental rights guaranteed and protected in many international human rights conventions, charters and other international and regional treaties and instruments. In Nigeria, the right has always been given recognision and specifically provided for in all the Nigeria’s constitutions, including the colonial and pre-independence. Even under the constitutional arrangements under the military governments, the said right is given recognition. Under the 1999 Constitution of Federal republic of Nigeria, the said right has also been prescribed for as one of the rights guaranteed for all Nigerians and anybody on the Nigerian soil. Nevertheless, it is one thing to recognize a right and it is completely another to practically implement the guarantees provided for. The Nigerian constitution is said to have given the said right with one hand and takes it away with another hand. This article critically analyses the right to freedom of expression under the Nigerian Constitution 1999 to discover whether or not the constitution as is being alleged, is really speaking from two sides of its mouth.
15
Ren, Jun, Koichi Morita et Ji Shun Pan. « Structure Observation & ; Identification Considering Soil-Structure Interaction of Story Stiffness and Damping Ratio of 8-Story Steel Encased Reinforce Concrete Structure by Microtremor ». Applied Mechanics and Materials 166-169 (mai 2012) : 1399–403. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1399.
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In this article, the authors identify the one built in 1998, eight-story structure of steel reinforced concrete body dynamic parameters, and discussed the soil - structure interaction on the identification results.In this study, an 8 degrees of freedom analytical model and the impact analysis model of soil-structure interaction to be established; through the analysis of microseismic observations, using non-parametric (transfer function and Random Decrement method) and parameter techniques (off-line system identification method, ARX :Auto-Regression with eXtra input) to identify the structure of the natural frequency, damping ratio and the story stiffness. Finally, in considering the soil-structure interaction cases, structural parameters were identification and compared the results to confirm the impact of soil-structure interaction.
16
Stephenson, W. R. « Observation of a directed resonance in soil driven by transverse rock motion ». Bulletin of the New Zealand Society for Earthquake Engineering 22, no 2 (30 juin 1989) : 81–89. http://dx.doi.org/10.5459/bnzsee.22.2.81-89.
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One component of horizontal ground acceleration recorded on flexible soil during the 1968 November 1 Cook strait earthquake is shown to be well modelled as a single degree of freedom oscillator excited by the recorded component of transverse acceleration in nearby bed rock.
This is shown to be consistent with the cellular resonant mode hypothesis of seismic response of flexible soil.
The mechanical oscillator is identified as a layer of fine-grained, post-glacial alluvium of approximately 20 m thickness.
17
S, Janani. « In Bharathi's Dream Vision, Women's Liberation and Soil Liberation ». International Research Journal of Tamil 4, S-11 (9 septembre 2022) : 57–63. http://dx.doi.org/10.34256/irjt224s117.
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An unparalleled poet of the 20th century, Bharathi was not only a progressive thinker but also a foreteller of future events. The former President of India, Abdul Kalam, said about dreams, "Dream! That dream is not the dream you see in your sleep. It's an ideal dream that keeps you awake." It is no exaggeration to say that Bharti dreamt of such an ideal many years before Kalam. Yes, India will be liberated anyway; we shall have breathed and swayed the air of liberation! Bharathi, who already knew that we have achieved blissful freedom by singing and dancing, it was Bharathi who sang the liberation anthem even before freedom. The most essential of his dreams are women's emancipation, unequal society, widow marriage, no child marriage, Tamil development, etc. Bharthi, who is very concerned about the welfare of women, says that women should get an education on par with men. Educating a girl only uplifts her. It will also uplift the community in which she belongs. Through that, our country becomes a superpower. Only then will the Indian flag fly in the world. Bharthi eagerly waits the day he will see Even though Bharthi's life had disappeared from this earth, he left the seeds of his dream deeply imprinted in our hearts. They started sprouting today. In today's time, we are travelling towards a higher level where men and women are equal. Many love marriages are taking place to bridge the caste differences. Widow Remarriages are encouraged. The government has passed several laws to prevent child marriage. Today's youth are working tirelessly to transform India into a superpower. It is certain that Bharathi's dream will soon come true through this.
18
Sakharov, Volodymyr O. « Dynamic Reductions for the Nonlinear Soil-Foundation-Structure System Interactions ». Civil and Environmental Engineering Reports 28, no 1 (1 mars 2018) : 146–58. http://dx.doi.org/10.2478/ceer-2018-0012.
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Abstract The article presents new dynamic superelements for DOF (degrees of freedom) reduction. Proposed spectral superelements (SES) are based on the method of normal coordinates. The developed superelements with basis nodes (SEB) for the inhomogeneous systems are also shown. Proposed superelements ensure to obtain the diagonal matrix of masses which allow to use the efficiency of explicit method. The results of nonlinear analysis using proposed reduction method for the group of high-rise building are presented. The calculations were performed by explicit method with the help of Automated System of Scientific Research (ASSR) “VESNA-DYN”.
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Rong, Yao, Yang Sun, LiQing Zhu et Xiao Xiao. « Analysis of the Three-Dimensional Dynamic Problems by Using a New Numerical Method ». Advances in Civil Engineering 2021 (4 mai 2021) : 1–12. http://dx.doi.org/10.1155/2021/5555575.
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The problems of the consolidation of saturated soil under dynamic loading are very complex. At present, numerical methods are widely used in the research. However, some traditional methods, such as the finite element method, involve more degrees of freedom, resulting in low computational efficiency. In this paper, the scaled boundary element method (SBFEM) is used to analyze the displacement and pore pressure response of saturated soil due to consolidation under dynamic load. The partial differential equations of linear problems are transformed into ordinary differential equations and solved along the radial direction. The coefficients in the equations are determined by approximate finite elements on the circumference. As a semianalytical method, the application of scaled boundary element method in soil-structure interaction is extended. Dealing with complex structures and structural nonlinearity, it can simulate two-phase saturated soil-structure dynamic interaction in infinite and finite domain, which has an important engineering practical value. Through the research, some conclusions are obtained. The dimension of the analytical problem can be reduced by one dimension if only the boundary surface is discretized. The SBFEM can automatically satisfy the radiation conditions at infinite distances. The 3D scaled boundary finite element equation for dynamic consolidation of saturated soils is not only accurate in finite element sense but also convenient in mathematical processing.
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Kodanda Rama Rao, P., S. R. K. Reddy, AHL Swaroop et K. Nagarjuna. « Seismic behavior of existing elevated water tanks resting on different type of foundations ». IOP Conference Series : Earth and Environmental Science 982, no 1 (1 mars 2022) : 012082. http://dx.doi.org/10.1088/1755-1315/982/1/012082.
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Abstract It has been well recognized that heavy structures built on soft soils, experience significant impact on seismic response, because of considerable foundation movements and hence, the effect of Soil-Structure-Interaction (SSI) can be a major factor while analyzing important structures like; nuclear power plants, elevated water tanks, chimneys, etc. against seismic forces. In general, elevated water tanks that were constructed on different type of soils in seismic regions, prior to the revision of seismic codes, must be checked on behavior and safety of such structures against earthquake loads as per present codes. In this paper, two similar elevated R.C. circular water tanks, each of 4.0 lakh liters capacity supported by two types of foundations; one with circular ring raft below the columns of tank resting on sandy soils, and the other with circular ring raft supported by piles embedded in black cotton soils, are chosen for carrying out seismic analysis. In the analysis, the water tank is idealized as a system with three degrees of freedom, treating the staging of tank as one spring attached to the mass of the water tank and the soil is treated with two springs; one in horizontal and the other in rocking mode, both attached to the soil mass and the response parameters like; time periods, base shears and displacements are worked out against earthquake loads. Results indicate that, irrespective of type of foundation, the soil play important role on seismic response of elevated water tanks by virtue of their configuration with top heavy mass and slender staging; particularly displacements are found high when they rest on loose soils. According to the new guidelines provided in the revised IS 1893 (Part-1) 2016 code, SSI effect should be considered in seismic analysis when the structure rests on loose or soft soils.
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Fernandez-Davila, Victor I., et Arnold R. Mendo. « Damping modification factors for the design of seismic isolation systems in Peru ». Earthquake Spectra 36, no 4 (22 juin 2020) : 2058–85. http://dx.doi.org/10.1177/8755293020926189.
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This study proposed a simple nonlinear equation to estimate damping modification factors (DMFs) to modify the elastic response spectral values for damping ratios between 10% and 50%. The DMFs are computed from the displacement, acceleration, and velocity response spectral of single-degree-of-freedom (SDOF) systems of 198 earthquake acceleration time histories from 40 earthquakes events of Peruvian database, grouped into three types of soil: hard soil, intermediate soil, and soft soil. For each soil group, 11 scaled records were selected according to the ASCE 7-16 standard to match the design spectrum of the Peruvian technical standard for seismically isolated structures E.031. Simplified approximate nonlinear period-dependent expressions were provided to compute DMFs from the Peruvian strong-motion database and were compared with DMFs available in the literature and national seismic design codes. The study showed discrepancies with the regulations worldwide.
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Kapoor, Rajni, et Nimai Das. « A Pragmatic Study for Enhancing Agricultural Efficiency through Labor Freedom ». Asian Journal of Agriculture and Rural Development 11, no 4 (25 octobre 2021) : 279–90. http://dx.doi.org/10.18488/journal.ajard.2021.114.279.290.
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The study aims to explore labor freedom in the agricultural sector for enhancing the efficiency of farming through policy change towards assigning property rights, rental contracts, and better wage-employment options to rural workers. Labor freedom emphasizes land reform and development policy for improving the economic status and capabilities of rural workers. The paper assessed the labor freedom index, weighted through agricultural property rights, labor wage contracts, and rural development policy. Data envelopment analysis is used to assess farm-level efficiency under the framework of Tobit regression for different size-based farm categories. Farm-level information was collected through a primary survey of 336 rural households of an advanced agricultural state in India. The study found a positive association between farm size and intensity of labor freedom, although the extent of freedom differs among farms. Size-specific variation was also observed for allocative efficiency such that marginal and medium-sized farms are more efficient than smaller ones. Tobit regression indicated labor freedom to be positively and significantly related to the efficiency of marginal, small and overall farms with enhancing efficiency of 25, 17 and nearly 20%, respectively; however, estimates of labor freedom insignificantly increased the efficiency of mediums farms, by 4.8%. This result suggests that labor freedom positive and significantly affects the efficiency of farms in general, and marginal and small farms in particular. Of course, the elasticity estimate of enhancing efficiency through labor freedom for medium farmers is found at a lower level.
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Padilla, Francisco, et Pierre Gélinas. « Un modèle pour l'infiltration dans les sols gelés tenant compte de la qualité de l'eau ». Canadian Journal of Civil Engineering 15, no 2 (1 avril 1988) : 263–71. http://dx.doi.org/10.1139/l88-034.
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The infiltration of water in frozen soils is solved using finite element methods for the numerical solution of water flow, heat, and solute transport in one dimension. These equations are coupled for the solution of Stefan's problem for different conditions of ice in soils. The degrees of freedom of this problem are soil temperature, water pressure, and solute concentration. A model is proposed to simulate the presence and formation of ice lenses in unsaturated and saturated soils. Early results are very promising when compared to analytical solutions.Two extreme cases are considered in applications: very wet and very dry soils. Frost heave and other parameters seem to have been properly simulated. The present model considers special phenomena related to colloidal soils; nevertheless, a comparison with field data is required. Key words: frozen soils, frost heave, unsaturated zone, heat transport, mass transport, Stefan problem, finite elements, phase change.
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Gerkus, Hande, Ying Lai, Asitha Senanayake, Robert B. Gilbert, Yunhan Huang, Joseph R. Giampa et Aaron S. Bradshaw. « Measuring Six-Degree-of-Freedom Movements of Buried Objects in Soil Using a Magnetometer ». Geotechnical Testing Journal 42, no 6 (5 décembre 2018) : 20170328. http://dx.doi.org/10.1520/gtj20170328.
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Boulkhiout, Radhwane, et Salah Messast. « Calculating the Dynamic Impedances of Foundations and their Effect on the Seismic Response of Structures : Analytical and Numerical Study ». Civil and Environmental Engineering Reports 31, no 2 (1 juin 2021) : 178–217. http://dx.doi.org/10.2478/ceer-2021-0026.
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Abstract This study evaluates the movement of a frame built on soft soil under seismic excitation taking into account soil-structure interaction. First, the study was evaluated using the finite element method, then, by using a substructure method which modelled the soil using springs and dampers in a linear and nonlinear study. Rheological models were determined using impedance functions, calculated using a numerical program CONAN. These dynamic impedances are shown in the displacement vector of a three-degrees-of-freedom frame, which was calculated on the basis of lateral forces distributed over the structure height using the equivalent static method. In this regard, two different calculation norms were chosen; RPA2003 and UBC97. Finally, a parametric study was carried out, based on the effects of soil densification and the foundation geometry on the response of the RC frame.
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Rahman, S. M. Tahmidur. « Nonlinear Dynamic Analysis of Lumped Soil Mass Model against Seismic Loading ». Saudi Journal of Civil Engineering 7, no 08 (3 septembre 2023) : 158–77. http://dx.doi.org/10.36348/sjce.2023.v07i08.001.
Texte intégralRésumé :
Soil yielding mechanisms and seismic load responses are the key areas of study. The true behavior of soil is revealed by nonlinear analysis. A clump of dirt is used for the analysis. In this study, the Finite Element Model (FEM) forms the basis for the mathematical formulas. Soil analysis in the case of a lumped mass takes into account the soil's one DOF, two DOF, and multi DOF degrees of freedom. In order to determine soil characteristics for MDOF, a soil bore log must be employed. In the instance of MDOF, the soil is composed of 12 distinct layers. SAP 2000 is used to conduct a nonlinear time-history analysis for this research. The hysteresis loops of nonlinear elastic, completely flexible soil undergo permanent deformation. Therefore, it is possible to get insight into the behavior of soil mass during an earthquake by studying lumped soil mass. The soil's nonlinear behavior is investigated using a variety of linear completely plastic hysteretic loops. Soil characteristics are shown to be crucial in this regard. Inadequate soil stiffness may result in persistent deformation, which in turn can lead structures to lean out of alignment. It is also noted that near the soil's surface, amplification is greatest.
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Mkandawire, Elina. « Evaluation of Traditional and Modernized Pest Control Methods Used by Smallholder Farmers in Malawi ». Current Agriculture Research Journal 5, no 1 (10 juin 2017) : 06–12. http://dx.doi.org/10.12944/carj.5.1.02.
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In order to compare the environmental performance of the existing pest control methods used by Malawian smallholder farmers a study was conducted to assess the environmental performance of two pest control methods used in cultivation of tomatoes (traditional pest control method vs. modernized pest control method). The study was conducted in two gardens, a farm using traditional pest control methods (Tikondwe Freedom Gardens) and another farm using modernized pest control techniques (Mgwirizano Farm Produce Club). The soil and tomato samples were analyzed, by liquid chromatography–mass spectrometry (LC–MS) with electrospray ionization (ESI) in positive mode. The results revealed the presence of pesticide residues at various concentration levels both in the soil and tomato samples. The concentrations of pesticide residues regarding the Mgwirizano Farm Produce Club Gardens were; for tomatoes, Dimethoate (1.2 - 3 ppm), L-Cyhalothrin, (0.2-3 ppm) Cypermethrin (< 0.03 ppm) Mancozeb (2-4 ppm) Chlorothalonil (0.02- 3ppm) while for soil samples, Dimethoate (<0.01 ppm), L-Cyhalothrin (<0.01ppm), Cypermethrin (<0.01ppm), Mancozeb (0.3- 1ppm) and Chlorothalonil (0.02- 2ppm). For comparison purposes tomato and soil samples collected from the field that uses traditional pest control methods (Tikondwe freedom farm) were also analyzed for pesticides residues and had the following outcome, the tomatoes had Dimethoate (< 0.01 ppm), L-Cyhalothrin, (0.01 ppm) Cypermethrin (< 0.01 ppm) Mancozeb (<0.01ppm) Chlorothalonil (<0.01 ppm) while the soil samples had concentrations of Dimethoate (0.03 ppm), L-Cyhalothrin (<0.01ppm), Cypermethrin (0.02ppm), Mancozeb (0.01ppm) and Chlorothalonil (0.01ppm). Furthermore, the study collected more information on health effects of pest management methodologies through Interviews with farmers, farm workers and health practitioners in rural areas where horticultural crops such as tomatoes are mostly cultivated using farm inputs, particularly pesticides.
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Murray, Hannah-Rose. « “The Black People’s Side of the Story” : The Historical and Transatlantic Roots of the Movement for Black Lives ». African American Review 56, no 1 (mars 2023) : 9–26. http://dx.doi.org/10.1353/afa.2023.a903595.
Texte intégralRésumé :
Abstract: Black freedom fighters have always been at the forefront pushing the United States to accept the ideals it was founded on and were—are—unrelenting in their groundbreaking campaigns for abolition, equality, and social justice. In this article, I argue that to add nuance and a greater understanding to the philosophies developed by such freedom fighters, it is necessary to evaluate the transatlantic connections between the United States and Britain. Complicating and expanding their calls for antiracism and anti-oppression, Black activists have gained an alternative international perspective on British soil. Beginning with a discussion of the Movement for Black Lives in the US and its links with the UK, I analyze the movement’s historical and transatlantic roots.
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Sameti, Amir Rezaei, et Mohammad Ali Ghannad. « Equivalent Linear Model for Existing Soil-Structure Systems ». International Journal of Structural Stability and Dynamics 16, no 02 (25 février 2016) : 1450099. http://dx.doi.org/10.1142/s0219455414500990.
Texte intégralRésumé :
The concept of equivalent linearization is extended for the soil-structure systems, in which the strength ratio (defined as the ratio of the yielding strength to the elastic strength demand) is known rather than the ductility ratio. The nonlinear soil-structure system is replaced by a linear single-degree-of-freedom (SDOF) system, which can capture the response of the actual system with sufficient accuracy. The dynamic characteristics of the equivalent linear SDOF system are determined through a statistical approach. The super-structure is modeled by an inelastic SDOF system with bilinear behavior, and the homogeneous half space beneath the structure by a discrete model, following the Cone Model. To cover a wide range of soil-structure systems, a comprehensive parametric study is conducted using a set of nondimensional parameters for the soil-structure system. The accuracy of the equivalent linear parameters is then assessed. The results confirm that the proposed equivalent linear model can capture the simultaneous effects of soil-structure interaction (SSI) and nonlinearity in the super-structure concerning the maximum inelastic response of the soil-structure system.
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Beaman, Lori G. « Battles Over Symbols : The “Religion” of the Minority Versus the “Culture” of the Majority ». Journal of Law and Religion 28, no 1 (janvier 2013) : 67–104. http://dx.doi.org/10.1017/s0748081400000242.
Texte intégralRésumé :
Moreover, with the benefit of hindsight, it is easy to identify in the constant central core of Christian faith, despite the inquisition, despite anti-Semitism and despite the crusades, the principles of human dignity, tolerance and freedom, including religious freedom, and therefore, in the last analysis, the foundations of the secular State.A European court should not be called upon to bankrupt centuries of European tradition. No court, certainly not this Court, should rob the Italians of part of their cultural personality.In March, 2011, after five years of working its way through various levels of national and European courts, the Grand Chamber of the European Court of Human Rights decided that a crucifix hanging at the front of a classroom did not violate the right to religious freedom under Article 34 of the Convention for the Protection of Human Rights and Fundamental Freedoms. Specifically, Ms. Soile Lautsi had complained that the presence of the crucifix violated her and her children's right to religious freedom and that its presence amounted to an enforced religious regime. The Grand Chamber, reversing the lower Chamber's decision, held that while admittedly a religious symbol, the crucifix also represented the cultural heritage of Italians.
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Fang, Liang, et Qi Fang Wang. « Frequency Domain Analysis of Multi-Degree of Freedom in Series Model SSI Effect with Translation and Rotation Input ». Advanced Materials Research 1065-1069 (décembre 2014) : 1457–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1457.
Texte intégralRésumé :
Based on the multi-degree of freedom in series model, structural displacement amplitude formula is derived in the frequency domain under the translation-rotation input situation, this formula indicates that the soil - structure interaction (SSI) could be considered as adding a correction term M˜ to the mass matrix of the structure with the hypothesis of Rigid foundation. This corrected mass matrix is actually a complex matrix, which related to the input frequency and damping. Equivalent translation-rotation input is coupled with two translation input components U* and Θ*. Besides, we uses case analysis to explain the characteristics of soil - structure interaction (SSI) in frequency domain by the end of this paper.
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Dong, Qiguang, Jichang Han, Na Lei, Jing He, Zenghui Sun, Yufei Xiong et Ya’nan Li. « Temporal and spatial variation of soil moisture of small watershed in gully catchment of the Loess Plateau of China ». E3S Web of Conferences 118 (2019) : 01009. http://dx.doi.org/10.1051/e3sconf/201911801009.
Texte intégralRésumé :
The temporal and spatial variation characteristics of soil moisture in typical slope and gully of Jiulongquangou small watershed were studied in the hilly and gully region of the Loess Plateau of China. The variation of soil moisture in the 0-30 cm layer on the surface of the hilly and gully region of the Loess Plateau is greater than the variation of soil moisture in each layer between 40 and 100 cm. In the study area, the model parameters such as coefficient of variation (Cv), nugget (C0), sill (C0+C), spatial degrees of freedom(C0/(C+C0)) and variable change can be used to quantitative analysis the spatial varying law. On the slope surface, the average soil water content and the coefficient of variation are negatively correlated, and can be approximated by an exponential function, while the two are positively correlated in the gully.
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Rahman, S. M. Tahmidur. « Seismic Analysis of the Soil Behavior and Titling of the Building ». Scholars Journal of Engineering and Technology 11, no 10 (10 octobre 2023) : 239–60. http://dx.doi.org/10.36347/sjet.2023.v11i10.002.
Texte intégralRésumé :
The mechanism of this yielding and its behavior under seismic loading of soil are the primary focus of this investigation. Nonlinear analysis is taken into account to see the real behavior of soil. In order to analyze soil, we employ both its solid mass and its lumped mass. In this study, the Finite Element Model (FEM) forms the basis for the mathematical formulas. Soil analysis in the case of a lumped mass takes into account the soil's one DOF, two DOF, and multi DOF degrees of freedom. In order to determine soil characteristics for MDOF, a soil bore log must be employed. In the instance of MDOF, the soil is composed of 12 distinct layers. SAP 2000 is used to do linear and nonlinear analysis of time series for this research. According to the findings, solid and lumped soil mass displacements are almost identical. Therefore, it is possible to get insight into the behavior of soil mass during an earthquake by studying lumped soil mass. The soil's nonlinear behavior is investigated using a variety of linear completely plastic hysteretic loops. Soil characteristics are shown to be crucial in this regard. Inadequate soil stiffness may result in persistent deformation, which in turn can lead structures to lean out of alignment. It is also noted that near the soil's surface, amplification is greatest.
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Han, Zejun, Mi Zhou, Xiaowen Zhou et Linqing Yang. « Dynamic Response of 3D Surface/Embedded Rigid Foundations of Arbitrary Shapes on Multi-Layered Soils in Time Domain ». International Journal of Structural Stability and Dynamics 19, no 09 (28 août 2019) : 1950106. http://dx.doi.org/10.1142/s0219455419501062.
Texte intégralRésumé :
Significant differences between the predicted and measured dynamic response of 3D rigid foundations on multi-layered soils in the time domain were identified due to the existence of uncertainties, which makes the issue a complicated one. In this study, a numerical method was developed to determine the dynamic responses of 3D rigid surfaces and embedded foundations of arbitrary shapes that are bonded to a multi-layered soil in the time domain. First, the dynamic stiffness matrices of the rigid foundations in the frequency domain are calculated via integral domain transformation. Secondly, a dynamic stiffness equation for rigid foundations in the time domain is established via the mixed variables formulation, which is based on the discrete dynamic stiffness matrices in the frequency domain. The proposed method can be applied to the treatment of systems with multiple degrees of freedom without losing the true information that concerns the coupling characteristics. Numerical examples are presented to demonstrate the accuracy of the proposed method for predicting the horizontal, vertical, rocking, and torsional vibrations. Further, a parametric study was carried out to provide insight into the dynamic behavior of the soil–foundation interaction (SFI) while considering soil nonhomogeneity. The results indicate that the elastic modulus of the soil has a significant impact on the dynamic responses of the rigid foundation. Finally, a numerical example of a rigid foundation resting on a six-layered, semi-infinite soil demonstrates that the proposed method can be used to deal with multi-layered media in the time domain in a relatively easy way.
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SAKAI, Kimitoshi, et Yoshitaka MURONO. « EQUIVALENT SINGLE DEGREE OF FREEDOM METHOD FOR SOIL DYNAMIC ANALYSIS OF THE MULTI-LAYERED GROUND ». Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & ; Earthquake Engineering (SE/EE)) 71, no 3 (2015) : 341–51. http://dx.doi.org/10.2208/jscejseee.71.341.
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KIMURA, Yukinobu, Kenji KAWANO et Makoto KURIWAKI. « Seismic performance evaluation on multi-degrees-of-freedom structure system with dynamic soil-structure interaction ». Journal of JAEE 3, no 1 (2003) : 37–46. http://dx.doi.org/10.5610/jaee.3.37.
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Patchamatla, J. Rama Raju, et P. K. Emani. « Time Domain Implementation of Consistent Boundaries for Continuum Two-Dimensional Wave Propagation Problems Using ABAQUS User-Defined Elements ». International Journal of Mathematical, Engineering and Management Sciences 7, no 2 (14 mars 2022) : 196–210. http://dx.doi.org/10.33889/ijmems.2022.7.2.013.
Texte intégralRésumé :
The present paper details the finite element implementation procedure for applying consistent boundaries for two-dimensional continuum soil-structure interaction systems. Consistent boundary conditions are ensured by applying rigorously calculated interaction forces at the truncated soil-structure interface. These calculations involve the evaluation of convolution integral on acceleration unit-impulse response functions for all boundary degrees of freedom for all time steps. The interactive or run-time evaluation of the interaction forces based on the past response history, is successfully carried out using user-defined element formulation in ABAQUS. This precise implementation of this boundary element procedure is demonstrated through benchmark problems and demonstrated through typical stress-wave propagation problems.
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Karinski, Yuri S., Avraham N. Dancygier et Aaron Chacha. « Evaluation of the contact pressure and response of a buried structure with a flat roof ». Canadian Journal of Civil Engineering 43, no 9 (septembre 2016) : 830–43. http://dx.doi.org/10.1139/cjce-2016-0040.
Texte intégralRésumé :
The paper presents a model to analyze the response of a buried structure to surface loading, which is based on a discrete-continuous concept, taking into consideration a possible variation of the soil arching coefficient with depth. The structure and the soil are represented by equivalent two degree of freedom and one-dimensional column system. The shear soil resistance is represented by a vertical friction traction that depends on the relative displacement between the column and the free field. At the bottom, the system is supported by a semi-infinite medium. An analytical solution for the mid-roof deflection and average contact pressure has been derived and verified against published experimental results. Examination of the effects of the soil parameters on the mid-roof deflection demonstrates their different weights in the analysis. The present model may be used for future solutions of corresponding dynamic problems, for which the variation of the arching coefficient with depth is especially important.
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Sung, Yu-Chi, et Chieh-Cheng Chen. « Z-Transferred Discrete-Time Infinite Impulse Response Filter as Foundation–Soil Impedance Function for SDOF Dynamic Structural Response Considering Soil–Structure Interaction ». Earthquake Spectra 35, no 2 (mai 2019) : 1003–22. http://dx.doi.org/10.1193/110117eqs225ep.
Texte intégralRésumé :
This paper proposed a novel dynamic structural analysis of a single-degree-of-freedom system considering soil–structure interaction (SSI). The z-transferred discrete-time infinite impulse response filter serving as a foundation–soil impedance function to get a transfer function between the ground displacement and foundation shear was proposed first. The corresponding time history of the foundation shear caused by a specific input of ground displacement can be determined through the filter obtained, and the succeeding structural responses are then able to be found by the base force propagating function. Case studies comparing the structural dynamic response with and without SSI were carried out. Without consideration of SSI, there was an overestimation of structural displacement for the structure with a shorter period, but in contrast to that, an underestimation for the structure with a longer period was concluded based on the results obtained.
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Li, S., Q. Quan, De Wei Tang, S. Jiang, X. Hou et Z. Deng. « Research on a Rotary-Percussive Coring Drill for Lunar Exploration ». Applied Mechanics and Materials 233 (novembre 2012) : 297–302. http://dx.doi.org/10.4028/www.scientific.net/amm.233.297.
Texte intégralRésumé :
China is launching the Chang'e project to send automated machine for acquiring the lunar soil and returning to the earth. Thus, we are trying to develop a kind of effective mechanism for the exploration mission of lunar soil coring. This paper presents a rotary-percussive coring drill which is a novel scheme for the deep surface soil acquirement. Two degrees of freedom are included in the proposed drill mechanism. Specifically-designed drill unit including auger and drill bit is employed to finish the coring of the simulant of lunar regolith. We have proposed a novel coring concept named soft-bag coring. Since there is no relative motion between the soft-bag and the cut soil core, the soft-bag method may keep the original stratification of lunar soil. A test-bed has been developed to conduct experimental tests under different drilling parameters and circumstances. The related drilling parameters such as rotary speed, penetration ratio, and percussive frequency are adjusted to adapt to different situations in the experiments. The experimental results indicate that the specifically considered drill mechanism with soft-bag inside can get high coring ratio and excellent stratification of the soil.
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Amiri, Amir Mohammad, Ali Ghanbari et Mahdi Derakhshandi. « An Analytical Model for Estimating the Vibration Frequency of Structures Located on the Pile Group in the Case of Floating Piles and End-bearing Pile ». Civil Engineering Journal 4, no 2 (6 mars 2018) : 450. http://dx.doi.org/10.28991/cej-0309105.
Texte intégralRésumé :
Exact estimation of vibration fundamental period of structures plays a vital role in their designing procedure. The proposition of a relatively exact expression which considers the effects of a pile group on the fundamental period of the structures was of less interest to previous researchers. This study aims to propose an analytical model and expression so as to estimate the free vibration period of the structures located on a pile group. To reach the objectives of this study, several numerical analyses has been carried out using the method of equivalent spring which takes into account the effects of soil-pile-structure interaction on the fundamental period of the structures. In the next step of the study the effects of a pile group on the fundamental period of the structures have been analyzed analytically. In this analytical study two cases have been considered for the piles which are end-bearing and floating piles. In the case of floating piles a five degrees-of-freedom analytical model and its corresponding expression have been proposed considering the soil-pile-structure system. The numerical modelling has been performed using the direct method due to the neglect of the soil in analytical expression and the results have been compared with those of the proposed analytical expression. The soil mass participation coefficient (λ) has been obtained using the discrepancy between the results of the two different methods to modify the analytical expression. In the case of end-bearing piles an analytical model with three degrees-of-freedom and its corresponding expressions has been proposed. Then the soil has been neglected and a new analytical expression has been proposed using the mass participation coefficients adopted from other researches to calculate the fundamental period of the structures. The comparison between the results of the proposed expression and those of case and numerical studies confirms that the proposed expressions benefit from a relative accuracy and can be used as an initial criterion in designing procedure.
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Sharonov, I. A., V. I. Kurdyumov, Yu M. Isaev et V. V. Kurushin. « TO THE ISSUE OF SPECIFICATION OF THE IMPACT FORCE OF UNBALANCED TILLAGE ROLLER ON THE SOIL ». Vestnik of Ulyanovsk state agricultural academy 212 (25 décembre 2021) : 13–18. http://dx.doi.org/10.18286/1816-4501-2021-4-13-18.
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Intensification of the process of soil compaction and structuring during sowing is possible on the basis of development of a new unbalanced tillage roller (UTR) equipped with disbalances rotating around the axis of a hollow cylinder. The rotation of disbalances leads to a change of the roller kinematic parameters and the nature of its impact on the soil. Having accepted the developed device as a material system with several degrees of freedom, we applied the Lagrange equation of the second kind to determine the kinematic parameters of the system, on the basis of which we obtained a system of second-order differential equations of the motion of the UTR in relation to generalized coordinates. The derived dependences made it possible to establish the kinematics peculiarities of the UTR at various masses of the hollow cylinder and disbalances. It was found that the impact of the UTR forms combined deformations of compression, shear and extension in the tilled soil environment, providing better fulfillment of agricultural requirements for rolling. It was revealed that the impact force of the UTR with rotating disbalances on the tilled soil environment has a periodic character of change, reaching a maximum of 1488 N with a mass of disbalances of 3 kg, their distance from the axis of the hollow cylinder by 0.25 m, the speed of the forward movement of the UTR of 3 m / s and disbalance rotation frequency 2 times higher than the hollow cylinder rotation frequency. The presence of this force intensifies the destruction process of soil clods and creates a structured and appropriately compacted soil layer in the area of seed placement. By changing the mass of UTR disbalances, their rotation frequency, relative position and position in relation to the hollow cylinder, it is possible to achieve exact compliance with agricultural requirements for rolling of various types of soils.
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Joel, Manasseh, et Joseph E. Edeh. « Soil Modification and Stabilization Potential of Calcium Carbide Waste ». Advanced Materials Research 824 (septembre 2013) : 29–36. http://dx.doi.org/10.4028/www.scientific.net/amr.824.29.
Texte intégralRésumé :
Laterite was treated with calcium carbide waste and lime as the control, to ascertain its modification and stabilization potential, in incremental order of 2% up to 10 %. Atterbergs limits test, compaction test, California bearing ratio (CBR) and unconfined compressive strength (UCS) test was performed on laterite treated with both additives. The use of χ2test to compare results of tests, showed that there is no significant difference between the modification potential of both additive as reflected in χ2values of 1.293, 0.995 and 0.650 obtained from the comparison of liquid limit, plastic limit and plasticity index test results. However difference was observed with CBR and 7 day UCS test results as χ2values of 13.75 and 11.64 respectively were higher than the standard value of 9.49 obtained from statistical Table at 4 degree of freedom and 5 % level of significance. Based on result of tests, calcium carbide waste is recommended for use in soil modification and stabilization, as usage will provide an effective way of disposing calcium carbide waste.
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Bell, Simon, Catharine Ward Thompson et Penny Travlou. « Contested views of freedom and control : Children, teenagers and urban fringe woodlands in Central Scotland ». Urban Forestry & ; Urban Greening 2, no 2 (janvier 2003) : 87–100. http://dx.doi.org/10.1078/1618-8667-00026.
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Henderson, B. L., et E. N. Bui. « An improved calibration curve between soil pH measured in waterand CaCl2 ». Soil Research 40, no 8 (2002) : 1399. http://dx.doi.org/10.1071/sr01098.
Texte intégralRésumé :
A new pH water to pH CaCl2 calibration curve was derived from data pooled from 2 National Land and Water Resources Audit projects. A total of 70465 observations with both pH in water and pH in CaCl2 were available for statistical analysis. An additive model for pH in CaCl2 was fitted from a smooth function of pH in water created by a smoothing spline with 6 degrees of freedom. This model appeared stable outside the range of the data and performed well (R2 = 96.2, s = 0.24). The additive model for conversion of pHw to pHCa is sigmoidal over the range of pH 2.5 to 10.5 and is similar in shape to earlier models. Using this new model, a look-up table for converting pHw to pHCa was created.
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Zhang, Jingfeng, Xiaozhen Li, Yuan Jing et Wanshui Han. « Bridge Structure Dynamic Analysis under Vessel Impact Loading considering Soil-Pile Interaction and Linear Soil Stiffness Approximation ». Advances in Civil Engineering 2019 (17 mars 2019) : 1–11. http://dx.doi.org/10.1155/2019/5173132.
Texte intégralRésumé :
The appropriate modeling of the soil-pile interaction (SPI) is critical to get the reasonable dynamic responses of bridge structure under impact loading. Of various SPI modeling approaches, utilizing p-y and t-z curves is a common method to represent the nonlinear lateral resistance and skin friction of pile-surrounding soil. This paper accomplished SPI modeling for the bridge pylon impact analysis with compression-only nonlinear springs and linear dashpots. The kinematic interaction and pile group effect were incorporated into the SPI. A variety of pylon impact analyses were conducted under energy-variation impact loads. The structure dynamic responses were compared and discussed considering the influences of pile group effect, soil damping, and axial t-z spring. An approximate approach was proposed to derive the linearized stiffness of soil for the purpose of engineering calculation. It was concluded from the extensive simulations that the impact load generated from higher initial energy induced more significant structural responses and larger soil inelastic deformation than smaller initial energy. The piles in the leading row possessed larger bending moments, whereas they exhibited smaller pile deformation than the responses of trailing row piles. Soil damping applied in SPI played positive roles on the reduction of structural responses. Replacing the t-z spring by fixing the degree-of-freedom (DOF) in the vertical direction was capable to yield satisfactory results of structural responses. The proposed linear soil stiffness was demonstrated to be applicable in the SPI modeling of structure impact analysis.
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Azira, Mohamed, et Lakhdar Guenfaf. « Empirical multi-degree-of-freedom-generalized minimum variance control for buildings during earthquakes ». Journal of Low Frequency Noise, Vibration and Active Control 37, no 1 (mars 2018) : 3–30. http://dx.doi.org/10.1177/1461348418760878.
Texte intégralRésumé :
Structural control of a multi-degree-of-freedom building under earthquake excitation is investigated in this paper. The ARMAX model calculation is developed for a linear representation of multi-degree-of-freedom structure. A control approach based on the generalized minimum variance algorithm is developed and presented. This approach is an empirical method to control the story unit regardless of the coupling with other stories. Kanai-Tajimi and Clough–Penzien models are used to generate the seismic excitations. Those models are calculated using the specific soil parameters. In order to test the control strategy performances under real strong earthquakes, the structure has been subjected to EL Cento earthquake. RST controller form shows the stability conditions and the optimality of the control strategy. Simulation tests using a 3DOF structure are performed and show the effectiveness of the control method using of the empirical method.
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Khoshnoudian, Faramarz, Ehsan Ahmadi, Mahdi Kiani et Mohammad Hadikhan Tehrani. « Dynamic Instability of Soil-SDOF Structure Systems under Far-Fault Earthquakes ». Earthquake Spectra 31, no 4 (novembre 2015) : 2419–41. http://dx.doi.org/10.1193/062613eqs170m.
Texte intégralRésumé :
A parametric study is devoted to investigating the dynamic instability of soil-structure systems under far-fault earthquakes. The superstructure and soil are simulated as a bilinear single-degree-of-freedom (SDOF) oscillator and based on the cone model concept, respectively. The results show that soil flexibility makes the system dynamically more unstable and that as the non-dimensional frequency increases, the collapse strength-reduction factor highly decreases. Moreover, increasing the aspect ratio leads to a lower collapse strength-reduction factor. However, its effect is found to be negligible. The effects of vibration period and post-yield slope on the collapse strength-reduction factor are the same as on the fixed-base condition. Additionally, comparison of collapse strength-reduction factors resulting from exact time history analyses with those proposed in FEMA 440 for the fixed-base condition shows a great underestimation with errors larger than 20% at approximately all cases and 60% at extreme cases. Finally, a formulation is calibrated using nonlinear regression analysis in order to estimate collapse strength-reduction factors of soil-structure systems.
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Xu, Shuo, Yinan Gu, Jing Sun et Dawei Tu. « Unique and accurate soil parameter identification for air-cushioned robotic vehicles ». Robotica 35, no 3 (14 septembre 2015) : 613–35. http://dx.doi.org/10.1017/s0263574715000739.
Texte intégralRésumé :
SUMMARYOn-line identification of soil parameters is a pre-condition of operating performance optimization and control for unmanned ground vehicles (UGV). Inverse calculation from measured vehicular operating parameters is a prevalent methodology. However, it inherently suffers from a multiple-solution problem caused by the coupling of soil parameters in terramechanics equations and an accuracy problem caused by the influences of state noise and measurement noise. These problems in tractive-force-related soil parameters identification were addressed here for air-cushioned vehicles (ACV) by taking advantage of their additional degree of control freedom in vertical force. To be specific, a g-function algorithm was proposed to solve the multiple-solution problem from reproductive tractive force equations; de-noising techniques consisting of mean-effect strategies, sampling points selection and sample rearrangement were employed to solve the accuracy problem. A series of experiments were conducted to evaluate these techniques at different noise levels and in different soil conditions. They got satisfactory results in terms of data utilization ratio, identification accuracy and performance stability. The contribution of the paper lies in inventing a novel algorithm for unique and accurate identification of tractive-force-related soil parameters without making any simplification to the original terramechanics equation and with robustness to variations of noise level and soil condition.
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Huynh, Van Quan, Xuan Huy Nguyen et Trung Kien Nguyen. « A Macro-element for Modeling the Non-linear Interaction of Soil-shallow Foundation under Seismic Loading ». Civil Engineering Journal 6, no 4 (1 avril 2020) : 714–23. http://dx.doi.org/10.28991/cej-2020-03091503.
Texte intégralRésumé :
This paper presents a macro-element for simulating the seismic behavior of the soil- shallow foundation interaction. The overall behavior in the soil and at the interface is replaced by a macro-element located at the base of the superstructure. The element reproduces the irreversible elastoplastic soil behavior (material non-linearity) and the foundation uplift (geometric non-linearity) at the soil- foundation interface. This new macro-element model with three degrees-of-freedom describes the force-displacement behavior of the footing center. The single element is restrained by the system of equivalent springs and dashpots. The footing is considered as a rigid body. It is solved by a suitable Newmark time integration scheme and implemented in Matlab to simulate the nonlinear behavior of soil-shallow foundation interaction under seismic loading. A reduce scaled soil-foundation system has been tested on a shaking table at the University of Transport and Communications, Hanoi, Vietnam. Five series of earthquake motions were used with maximum acceleration increased from 0.5 to 2.5 . The comparison of numerical results obtained from the simulation and experimentations shows the satisfactory agreement of the model. The proposed macro-element can be used to predict the seismic behavior of a wider variety of configurations.