Ammonia utilization and synthesis

Call number: LD2668 .R4 1968 E4

A GIS-based examination of residential dwelling figures in Newcastle Upon Tyne : comparison of the 1991 census and the local authority housing data

The study compares the total number of dwellings in Newcastle-upon-Tyne according to the 1991 Census and the local authority Housing Department. This is to assess whether the explanation of the differences at the local scale, can contribute to the understanding of Census underenumeration at the national scale. The significance of dwelling figures is established by reference to Census underenumeration, the Estimating with Confidence (EwC) project, housing need and government finance. The study also draws on literature about GIS in local government in order to highlight the need for the local analysis of dwelling figures for research and policy purposes, and to demonstrate the benefits of integrating Census and local authority data. The study describes the processes of data collection, integration and interpretation from both the Census and local authority sources. Total residential dwellings, occupied council stock and total vacant dwellings from both sources are compared and the differences are standardised. The standardised differences are then mapped (using z- scores) at the District scale and at Housing Area, Housing Neighbourhood, Ward and ED resolutions. Areas with large differences above or below the expected differences are highlighted and their characteristics are noted. The observed differences are then correlated with some of the characteristic of the areas in the form of dwelling structure, tenure, imputed residents and accommodation not used as main residence. These characteristics are then compared with those of areas with EwC non-response adjustment figures. The correlation analysis is carried out at two scales with the same resolution. This includes all the EDs in the City, then focuses on the EDs within Benwell and Scotswood Wards. This is to highlight the significant associations, specific to these Wards. Benwell and Scotswood are selected because of their patterns of vacancy differences, which are found to be in contrast to the city-wide pattern. The Census excess of vacancies in these Wards are also found to be greater than those in other Wards and greater (more than 1.4 standard deviations) than the city-wide expected average difference. The correlation analysis at the City scale finds that EDs with higher Census vacancy counts than the local authority data, share similar characteristics with EDs containing high EwC non-response adjustment figures. These are EDs with greater number of flats in residential buildings and local authority rented dwellings. In Benwell and Scotswood this pattern changes to greater number of flats in commercial buildings, converted flats and privately rented dwellings. The last stage of the study explains the differences in the selected variables using the individual property records (ED profiles). The study finds that at District (City) scale, the Census counts of total residential dwellings and occupied council stock are slightly higher than those from the local authority data. The Census vacancy figures however, are significantly less than local authority figures, mainly due to definitional differences and data collection methods used. The opposite pattern of higher Census vacancy figures is observed in Benwell and Scotswood. The reason for this is found to be due to vacant dwellings awaiting demolition, which were included in the 1991 Census vacancy figures but not in the local authority datasets. An example of how different definitions and data collection methods caused the observed differences. The study illustrates that the comparison of local authority and Census data can highlight areas with large differences (in vacant, occupied council stock or total residential dwelling counts) through data standardisation. The characteristics of these areas are found to be similar to those of areas reported as difficult to enumerate, in the national studies of Census underenumeration. The study also illustrates that these differences can be associated with Census non-response an..

Cubical rectangles and rectangular lattices

Cubical rectangles are being defined and explored here over the $n-$dimensional geometric cube $Q_n.$ They form a new class of geometric objects that includes all the edges and all the squares of the $n-$cube. We enumerate and characterize them here in order to construct new posets, transforming into special lattices that will be called rectangular lattices. We show that rectangular lattices are closely related to the class of cubical lattices, that is, the face lattice of the $n-$cube

The Effect of Si and Extrusion Process on the Microstructure and Tensile Properties of Mg-Mg2Si Composite

AbstractThis investigation has been carried out to study the influence of extrusion process on microstructure and tensile properties of Mg-Mg2Si composite with different amounts of Si (3, 5 and 7wt.%). Microstructural examination was carried out using optical microscopy (OM). The cast specimens were extruded at 350°C at different extrusion ratios (6:1, 12:1 and 18:1). The results showed that the specimens with lower Si contents, have higher ultimate tensile strength (UTS) and tensile elongation values. Moreover, there was a considerable improvement in tensile properties for the specimens extruded with the ratio of 12:1 and 18:1 in comparison to the specimens of 6:1. This can be attributed to the significant reduction in size of primary Mg2Si particles from more than 200μm to 20μm, 10μm and 5μm after extrusion with the ratio of 6:1, 12:1 and 18:1, respectively. The highest UTS values were found to be 265MPa for extruded with 1:18 ratio of Mg-3Si composite

Highly parallel multi-physics simulation of muscular activation and EMG

Simulation of skeletal muscle activation can help to interpret electromyographic measurements and infer the behavior of the muscle fibers. Existing models consider simplified geometries or a low number of muscle fibers to reduce the computation time. We demonstrate how to simulate a finely-resolved model of biceps brachii with a typical number of 270.000 fibers. We have used domain decomposition to run simulations on 27.000 cores of the supercomputer HazelHen at HLRS in Stuttgart, Germany. We present details on opendihu, our software framework. Its configurability, efficient data structures and modular software architecture target usability, performance and extensibility for future models. We present good parallel weak scaling of the simulations

Effect of Microstructural Refinement on Tensile Properties of AZ80 Magnesium Alloy via Ca Addition and Extrusion Process

AbstractThe microstructure and tensile properties of AZ80+X%Ca (X=0, 0.1, 0.5) magnesium alloy have investigated after applying extrusion process at 280°C and 340°C. Optical and scanning electron micrographs parallel to extrusion direction at 280°C showed dynamically recrystallized grains. There were also initial grains elongated in extrusion direction in the AZ80+X%Ca alloy. Finer microstructures were observed by increasing calcium content due to the formation of some precipitates during grain growth. EDS analysis determined the newly formed precipitates as Al2Ca. The grain size was reduced from 90μm to 9μm by extrusion process in the sample with 0.5% Ca. At higher extrusion temperature (340°C), similar microstructure was observed, except that the grain size was increased and there was no initial grains left in the structure anymore. From tensile testing, ultimate tensile strength (UTS) value was increased from 304MPa to 329MPa in extruded AZ80+0.5%Ca alloy at 280°C

A high-order fully coupled electro-fluid-dynamics solver for multiphase flow simulations

A high-order discontinuous Galerkin Finite Element solver is developed for solving electro-fluid-dynamics problems. The solver is employed to perform numerical simulations of deformation of a droplet suspended in another immiscible liquid by applying steady and oscillatory electric fields. The level set method is adopted to represent the common interface of the droplet and surrounding medium. Electrostatics equation with a jump in the dielectric property at the interface is solved to find the electric field distribution. The incompressible Navier-Stokes equations including the surface tension force are solved to find the flow field. The Electrostatics and Navier-Stokes equations are coupled through changes in the geometry because of the deformation of the droplet and the dielectrophoretic body force, which is present at the interface

Numerical simulation of deformation of a droplet in a stationary electric field using DG

Numerical simulation of deformation of a droplet in a stationary electric field is performed in the present research. The droplet is suspended in another immiscible fluid with the same density and viscosity but a different dielectric property (permittivity). By applying the electric field, the fluids are polarized that gives rise to mechanical forces and deformation. A two-way coupling occurs because of the forces exerted from the electric field on the droplet and the deformation of the droplet which changes the geometry for the electric field calculations. The droplet continues to deform until a force balance between the electric force, pressure and the surface tension is achieved and the droplet becomes a spheroid. An electromechanical approach is adopted to solve the above mentioned problem, which includes solving the governing equations of both the electric and fluid fields, computing the coupling forces and capturing the movement of the interface of the droplet and the surrounding fluid. A one-fluid approach is followed, which enables us to solve one set of the governing equations for both the droplet and the surrounding fluid. The interface is represented as the zero iso-value of a level set function and an advection equation is solved to find the movement of the interface. A diffuse interface model is used to regularize the jump in the fluid and electric properties. The governing equations of the electric and fluid fields and the level set advection equation are discretized using the Discontinuous Galerkin Finite Element method (DG) in the BoSSS code for solving conservation laws. The electric field is computed from the electric potential by considering the electrostatic equations. To find the electric potential, a Laplace equation is solved which has a jump in the permittivity at the interface. The Laplace equation is discretized using the interior penalty method (IP) which we modified for the case of high jumps in the permittivity. Assuming that the fluids are linear dielectric materials, the electric force is the dielectrophoretic force which is computed from the Kortweg-Helmholtz formula. This force is added as a body force to the incompressible Navier-Stokes equations, which are the governing equations for the fluid flow. Considering that there is no jump in the fluid properties, a single phase solver of the Navier-Stokes equations including the surface tension at the interface is developed. The surface tension force is added as a body force to the Navier-Stokes equations using the continuum surface force model (CSF). This model is known for producing a spurious velocity field. To decrease the spurious velocities, the surface tension term is calculated by using high degree polynomials for a precise calculation of the normal vector and curvature. To solve the incompressible Navier-Stokes equations using the DG method, a projection scheme with a consistent Neumann pressure boundary condition is employed and the same polynomial order for the velocity and pressure (equal-order method) is applied. Using the above-mentioned pressure boundary condition leads to an optimal convergence rate of k + 1 in the L2-norm for the pressure, which is not reported from other DG solvers. However, using the DG method, we have observed that discontinuities in the solutions at the cell boundaries can affect the solution accuracy and even cause a numerical instability. These accuracy and stability issues occur when the derivatives of the solution are computed. Therefore a flux-based method for calculation of the derivatives of the flow variables was adopted. As the results showed considerably improved accuracy and stability characteristics, we used the proposed method also in solving the above mentioned coupled problem