GRChombo : Numerical Relativity with Adaptive Mesh Refinement

In this work, we introduce GRChombo: a new numerical relativity code which incorporates full adaptive mesh refinement (AMR) using block structured Berger-Rigoutsos grid generation. The code supports non-trivial "many-boxes-in-many-boxes" mesh hierarchies and massive parallelism through the Message Passing Interface (MPI). GRChombo evolves the Einstein equation using the standard BSSN formalism, with an option to turn on CCZ4 constraint damping if required. The AMR capability permits the study of a range of new physics which has previously been computationally infeasible in a full 3+1 setting, whilst also significantly simplifying the process of setting up the mesh for these problems. We show that GRChombo can stably and accurately evolve standard spacetimes such as binary black hole mergers and scalar collapses into black holes, demonstrate the performance characteristics of our code, and discuss various physics problems which stand to benefit from the AMR technique.Comment: 48 pages, 24 figure

Passive CO₂ removal in urban soils:evidence from brownfield sites

Management of urban brownfield land can contribute to significant removal of atmospheric CO2 through the development of soil carbonate minerals. However, the potential magnitude and stability of this carbon sink is poorly quantified as previous studies address a limited range of conditions and short durations. Furthermore, the suitability of carbonate-sequestering soils for construction has not been investigated. To address these issues we measured total inorganic carbon, permeability and ground strength in the top 20 cm of soil at 20 brownfield sites in northern England, between 2015 and 2017. Across all sites accumulation occurred at a rate of 1–16 t C ha−1 yr−1, as calcite (CaCO3), corresponding to removal of approximately 4–59 t CO2 ha−1 yr−1, with the highest rate in the first 15 years after demolition. C and O stable isotope analysis of calcite confirms the atmospheric origin of the measured inorganic carbon. Statistical modelling found that pH and the content of fine materials (combined silt and clay content) were the best predictors of the total inorganic carbon content of the samples. Measurement of permeability shows that sites with carbonated soils possess a similar risk of run-off or flooding to sandy soils. Soil strength, measured as in-situ bearing capacity, increased with carbonation. These results demonstrate that the management of urban brownfield land to retain fine material derived from concrete crushing on site following demolition will promote calcite precipitation in soils, and so offers an additional CO2 removal mechanism, with no detrimental effect on drainage and possible improvements in strength. Given the large area of brownfield land that is available for development, the contribution of this process to CO2 removal by urban soils needs to be recognised in CO2 mitigation policies

Dynamic Response of an Actual Hammer Foundation

During the operation of Hammers and other shock producing machines, strong dynamic effects are generated which depend on the interaction between the different elements of the system. A simple two-degree of freedom system comprising of mass and spring, may offer reasonable result. Better result may be obtained by Wave Equation approach. This paper compares these two numerical schemes with the observed behavior of one Belt-drop stamping hammer

Pregnancy in dialysis patients: a case series

Fertility is markedly reduced in patients with chronic renal failure. For women with pre-existing renal disease, pregnancy is associated with an increased rate of fetal complications and a considerable risk of renal disease progression. Due to substantial improvements in antenatal and neonatal care, fetal outcome has improved considerably in the last two decade

Damage and Remedial Measures for Buildings on Hill Slopes

The paper deals with details of geotechnical investigations carried out for evaluating the reasons of damage to the buildings resting on hill slopes in northern region of India and also to evaluate the soil parameters for designing retaining walls and other remedial measures for preventing further damage to structures. Three causes of failure were identified namely (i) instability of slopes, (ii) improper design of retaining walls and (iii) differential settlement of structures. Shear strength parameters of the soil mass required for the analysis of slope stability and stability of retaining wall sections have been chosen based on three methods of investigations viz. large scale direct in-situ shear tests, plate load tests and the back analysis method. The stability analysis of various sections of slopes have been carried out and measures for strengthening of slopes have been suggested