65 research outputs found
Behaviour of Shallow Strip Foundation on Granular Soil Under Eccentrically Lnclined Load
Since the publication of Terzaghiâs theory on the ultimate bearing capacity of shallow foundations in 1943, results of numerous studiesâboth theoretical and experimentalâby
various investigators have been published. Most of the studies relate to the case of a vertical load applied centrally to the foundation. Meyerhof (1953) developed empirical procedures for estimating the ultimate bearing capacity of foundations subjected to eccentric and inclined loads. Based on the review of the existing literature on the bearing capacity of shallow foundations, it appears that limited attention has been paid to estimate the ultimate bearing capacity when the foundation is subjected to both eccentric and inclined load and the objective of present study stems from this paucity. Besides, only a few studies have been made to estimate the average settlement of embedded footings when subjected to eccentric load.In order to arrive at the objective and to quantify certain parameters, extensive laboratory model tests have been conducted to determine the ultimate bearing capacity of shallow strip foundation resting over sand bed and subjected to eccentric and inclined loads. The tests have been conducted on two types of sand i.e. dense sand and medium dense sand.
The load inclination has been varied from 00 to 200 whereas the eccentricity varies from 0 to 0.15B (B = width of footing). Depth of the footing is varied from 0 to B. Traditionally,in all analysis of such problems; the line of load application is towards the center line of the footing. However, in this thesis, it is investigated for the two possible ways of load application i.e. (i) towards and (ii) away from the center line of the footing.Based on the model test results, an empirical non-dimensional reduction factor has been developed for each mode of load application. This reduction factor will compute the ultimate bearing capacity of footing subjected to eccentric and inclined load by knowing the ultimate bearing capacity of footings under centric vertical load at the same depth of footing. Similarly, neural network models have been developed under each mode of load application and combined mode of load application to compute reduction factor as described above. Finally, the developed equations are compared with the existing theories.vi In addition to bearing capacity, the settlement of eccentrically loaded embedded footings is investigated. Based on some of those laboratory test results as discussed above, an empirical procedure has been developed to estimate the average settlement of the foundation subjected to an average allowable eccentric load per unit area, where the applied load is vertical
From jhum to broom: Agricultural land-use change and food security implications on the Meghalaya Plateau, India
Human population growth in the developing world drives land-use changes, impacting food security. In India, the dramatic change in demographic dynamics over the past century has reduced traditional agricultural land-use through increasing commercialization. Here, we analyze the magnitude and implications for the farming system by the introduction of cash-cropping, replacing the traditional slash and burn rotations (jhum), of the tribal people on the Meghalaya Plateau, northeast India, by means of agricultural census data and field surveys conducted in seven villages. Land-use change has brought major alterations in hill agricultural practices, enhanced cash-cropping, promoted mono-cropping, changed food consumption patterns, underpinned the emergence of a new food system, and exposed farmers and consumers to the precariousness of the market, all of which have both long- and short-term food security implications. We found dietary diversity to be higher under jhum compared to any of the cash-crop systems, and higher under traditional cash-cropping than under modern cash-cropping
Ultimate bearing capacity of shallow strip foundation under eccentrically inclined load - a critical assessment
An empirical non-dimensional reduction factor has been developed in this paper using 192 laboratory model test results of the previous studies made by authors for a strip foundation supported by sand and subjected to eccentrically inclined load for both types of loading, i.e. line of load application inclined towards the centre line of the foundation (partially compensated case) and away from the centre line of the foundation (reinforced case). The reduction factor is the ratio of the ultimate inclined load per unit area of the foundation subjected to an eccentrically inclined load (i.e. partially compensated or reinforced loading) to the ultimate bearing capacity of the same foundation subjected to a centric vertical load at the same embedment ratio, Df/B. The developed reduction factor has been compared with those based on the earlier bearing capacity studies in this area available in the literature. The comparison seems to be reasonably good
Standalone Instrumented Posterior Approach Used as Universal Approach for Tuberculosis Spondylodiscitis
Background: Surgical management of spinal tuberculosis (TB) has been classically the anterior, then combined, and of late increasingly by the posterior approach. The posterior approach has been successful in early disease. There has been a paradigm shift and inquisitive to explore this approach in the more advanced and even long-segment disease. Our study is a retrospective analysis by authors in variable disease pattern of TB Spine operated at an institute using a single posterior approach. Settings and Design: A retrospective case study series in a tertiary level hospital. Aims: The aim of this study is to evaluate the functional and radiological results of an all posterior instrumented approach used as a âuniversal approachâ in tubercular spondylodiscitis of variable presentation. Materials and Methods: The study is from January 2015 to May 2018. Twenty-four of 38 patients met the inclusion criterion with a male: female = 8:16, and mean age 44.26 years. The initial diagnosis of TB was based on clinic-radiologic basis. Their level of affection, number of vertebrae affected, and vertebral body collapse, the kyphosis (preoperative, predicted, postoperative, and final residual) and bony fusion were measured in the preoperative, postoperative, and final X rays. Functional scoring regarding visual analog scale and Frankel neurology grading was done at presentation and follow-up of patients. Histopathological data of all patients were collected and anti-tubercular therapy completed for a period of 1 year with 4 drugs (HRZE) for 2 months and 2 drugs (HR) for rest of period. Statistical Analysis Used: The descriptive data were analyzed by descriptive statistics, and other parameters were calculated using the appropriate statistical tests such as the Student paired t-test for erythrocyte sedimentation rate, visual analog scale score, and kyphosis. Results: The mean number of vertebrae involved was 3.29 ± 0.86 (2â6) with mean vertebral body destruction was 0.616. Preoperatively, the mean kyphosis angle was 22.42° ± 12.56° and was corrected postoperatively to 13.08° ± 11.34° with an average correction of 9.34° (41.66%). At the latest follow-up, there was mean loss of correction of 0.80° resulting in 13.88° of final correction. Bony fusion was achieved in 20 patients (83.33%) cases. Neurological recovery occurred in all patients (100%), and 92% could be ambulatory at 1 year follow-up. There was improvement of visual analog scale from 6.33 ± 1.05 preoperatively to 1.042 ± 0.75 at 3 months of postoperative period. Two patients had bed sore, two had urinary infection, and one had neurological worsening requiring re exploration and cage removal eventually recovering to Frankel E. Two patients died due to unrelated cause. Conclusions: The procedure in safe and has satisfactory results in variable group affection of Pottâs spine including early and late disease, multisegment involvement using pedicle screw fixation with/without cage support
From jhum to broom: Agricultural land-use change and food security implications on the Meghalaya Plateau, India
Analysis of the apparent nuclear modification in peripheral PbâPb collisions at 5.02 TeV
International audienceCharged-particle spectra at midrapidity are measured in PbâPb collisions at the centre-of-mass energy per nucleonânucleon pair sNN=5.02 TeV and presented in centrality classes ranging from most central (0â5%) to most peripheral (95â100%) collisions. Possible medium effects are quantified using the nuclear modification factor ( RAA ) by comparing the measured spectra with those from protonâproton collisions, scaled by the number of independent nucleonânucleon collisions obtained from a Glauber model. At large transverse momenta ( 8<pT<20GeV/c ), the average RAA is found to increase from about 0.15 in 0â5% central to a maximum value of about 0.8 in 75â85% peripheral collisions, beyond which it falls off strongly to below 0.2 for the most peripheral collisions. Furthermore, RAA initially exhibits a positive slope as a function of pT in the 8â20 GeV/c interval, while for collisions beyond the 80% class the slope is negative. To reduce uncertainties related to event selection and normalization, we also provide the ratio of RAA in adjacent centrality intervals. Our results in peripheral collisions are consistent with a PYTHIA-based model without nuclear modification, demonstrating that biases caused by the event selection and collision geometry can lead to the apparent suppression in peripheral collisions. This explains the unintuitive observation that RAA is below unity in peripheral PbâPb, but equal to unity in minimum-bias pâPb collisions despite similar charged-particle multiplicities
Anisotropic flow of identified particles in Pb-Pb collisions at TeV
The elliptic (v), triangular (v), and quadrangular (v) flow coefficients of Ï, K, , and the Ï-meson are measured in Pb-Pb collisions at TeV. Results obtained with the scalar product method are reported for the rapidity range |y| < 0.5 as a function of transverse momentum, p, at different collision centrality intervals between 0â70%, including ultra-central (0â1%) collisions for Ï, K, and . For p < 3 GeV/c, the flow coefficients exhibit a particle mass dependence. At intermediate transverse momenta (3 < p < 8â10 GeV/c), particles show an approximate grouping according to their type (i.e., mesons and baryons). The Ï-meson v, which tests both particle mass dependence and type scaling, follows v at low p and Ï v at intermediate p. The evolution of the shape of v(p) as a function of centrality and harmonic number n is studied for the various particle species. Flow coefficients of Ï, K, and for p < 3 GeV/c are compared to iEBE-VISHNU and MUSIC hydrodynamical calculations coupled to a hadronic cascade model (UrQMD). The iEBE-VISHNU calculations describe the results fairly well for p < 2.5 GeV/c, while MUSIC calculations reproduce the measurements for p < 1 GeV/c. A comparison to v coefficients measured in Pb-Pb collisions at TeV is also provided
Production of the Ï(770)0 meson in pp and PbâPb collisions at âsNN = 2.76 TeV
The production of the Ï(770)0 meson has been measured at mid-rapidity (|y|<0.5) in pp and centrality differential Pb-Pb collisions at sNNââââ = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The particles have been reconstructed in the Ï(770)âÏ+Ïâ decay channel in the transverse momentum (pT) range 0.5â11 GeV/c. A centrality dependent suppression of the ratio of the integrated yields 2Ï(770)0/(Ï++Ïâ) is observed. The ratio decreases by âŒ40% from pp to central Pb-Pb collisions. A study of the pT-differential 2Ï(770)0/(Ï++Ïâ) ratio reveals that the suppression occurs at low transverse momenta, pT<2 GeV/c. At higher momentum, particle ratios measured in heavy-ion and pp collisions are consistent. The observed suppression is very similar to that previously measured for the Kâ(892)0/K ratio and is consistent with EPOS3 predictions that may imply that rescattering in the hadronic phase is a dominant mechanism for the observed suppression
Measurement of the inclusive J/ polarization at forward rapidity in pp collisions at  TeV
We report on the measurement of the inclusive J/ polarization parameters in pp collisions at a center of mass energy  TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.23 pb . J/ resonances are reconstructed in their di-muon decay channel in the rapidity interval and over the transverse-momentum interval  . The three polarization parameters ( , , ) are measured as a function of both in the helicity and Collins-Soper reference frames. The measured J/ polarization parameters are found to be compatible with zero within uncertainties, contrary to expectations from all available predictions. The results are compared with the measurement in pp collisions at  TeV
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