Rapid tooling application for the evaluation of a greensand casting defect

Abstract: The ability to produce production quality tooling, directly from CAD data, through additive manufacturing (AM) processes has obvious advantages with regards to the reduced lead time and labour costs. This, together with the ability to simulate the metal casting process, opens new doors for researchers in the field of metal casting. This paper reviews the suitability of tooling produced in PA 2200 polyamide material, for use in a research environment, where the failure of greensand, a mixture of silica sand, bentonite (clay) and water, is to be replicated as it would occur in an industrial setting

Toward a Framework for Levels of Robot Autonomy in Human-Robot Interaction

Autonomy is a critical construct related to human-robot interaction (HRI) and varies widely across robot platforms. Levels of robot autonomy (LORA), ranging from teleoperation to fully autonomous systems, influence the way in which humans and robots interact with one another. Thus, there is a need to understand HRI by identifying variables that influence—and are influenced by—robot autonomy. Our overarching goal is to develop a framework for LORA in HRI. To reach this goal, our framework draws links between HRI and human-automation interaction, a field with a long history of studying and understanding human-related variables. The construct of autonomy is reviewed and redefined within the context of HRI. Additionally, this framework proposes a process for determining a robot’s autonomy level by categorizing autonomy along a 10-point taxonomy. The framework is intended to be treated as a guideline for determining autonomy, categorizing the LORA along a qualitative taxonomy and considering HRI variables (e.g., acceptance, situation awareness, reliability) that may be influenced by the LOR

Perfection of materials technology for producing improved Gunn-effect devices

Chemical vapor deposition system for improved Gunn effect devices using arsenic chloride 3 metho

Direct neutron capture of 48Ca at kT = 52 keV

The neutron capture cross section of 48Ca was measured relative to the known gold cross section at kT = 52 keV using the fast cyclic activation technique. The experiment was performed at the Van-de-Graaff accelerator, Universitaet Tuebingen. The new experimental result is in good agreement with a calculation using the direct capture model. The 1/v behaviour of the capture cross section at thermonuclear energies is confirmed, and the adopted reaction rate which is based on several previous experimental investigations remains unchanged.Comment: 9 pages (uses Revtex), 2 postscript figures, accepted for publication as Brief Report in Phys. Rev.

Yield response of corn in a Planosol soil to subsurface drainage with variable tile spacings

The Edina soil series of southeastern Iowa and northern Missouri are soils of relatively flat topography and poor internal drainage. The need for research data on the feasibility of drainage (both surface and subsurface) on the Edina soils was recognized at the time experiments were begun on the Southern Iowa Experimental Farm, Davis County, Iowa. The yield response of corn to surface drainage by bedding was summarized and reported by Beer et al.3 in 1961. Since initiation of the subsurface drainage experiment in 1949, data on crop-yield response to tile drainage have been collected. The purpose of this bulletin is to present the results of this study as related to the effects of tile drainage on crop yields, with the emphasis on corn, during the period of record. The nature of tile discharge during the growing seasons from 1951 to 1963 also is presented

Response of corn yields in a Planosol soil to surface drainage, cropping system and variable fertilizer treatments

The Edina soil series of southeastern Iowa and northern Missouri are areas of relatively flat topography and poor internal drainage. For these areas, where the topography and soils permit, surface drainage is the most practical method of removing excess water from the land. One method of surface drainage that has been used on the Edina soils is bedding, in which the field is divided into narrow-width plow lands with the deadfurrows running parallel to the prevailing land slope. Little is known about the relative returns from investment in a bedding system in comparison with other surface or subsurface drainage methods. Bedding requires that some topsoil be moved to obtain the desired grade for drainage. The effect on crop yields of topsoil removal and movement in land-forming operations such as bedding, however, is not quantitatively understood. It is the general purpose of this bulletin to present and analyze 6 years of corn-yield data involving drainage (bedded versus level), cropping and fertilizer variables from a study on the Southern Iowa Experimental Farm near Bloomfield

Interrelationships of plant population, soil moisture and soil fertility in determining corn yields on Colo clay loam at Ames, Iowa

This investigation included a 6-year study of the effects of irrigation, stand and fertility treatments on com yields on a clay loam soil near Ames, Iowa. The data obtained from 1956 to 1961 indicated that variations in yields were caused by all three variables. Significant yield differences caused by irrigation treatments were greatest in 1956, 1959 and 1960. The highest mean irrigated yields averaged over stand and fertility treatments usually correlated best with the irrigation treatment where the soil moisture was maintained at or above 60 percent of the available moisture content (AMC). The greatest yield response to irrigation occurred in 1956, primarily because of the very dry conditions throughout the entire growing season. In 1956, each inch of water increased yield by 2.7 bushels per acre up to the 60-percent AMC level. Beyond this point, maintaining soil moisture at 90 percent or greater of field capacity reduced yield per increment of added water. There was not a significant response to irrigation in 1957, 1958 and 1961, primarily because of ample soil moisture storage and good rainfall distribution at critical periods during the growing season

The changing patterns of group politics in Britain

Two interpretations of ways in which group politics in Britain have presented challenges to democracy are reviewed: neo-corporatism or pluralistic stagnation and the rise of single issue interest groups. The disappearance of the first paradigm created a political space for the second to emerge. A three-phase model of group activity is developed: a phase centred around production interests, followed by the development of broadly based 'other regarding' groups, succeeded by fragmented, inner directed groups focusing on particular interests. Explanations of the decay of corporatism are reviewed. Single issue group activity has increased as party membership has declined and is facilitated by changes in traditional media and the development of the internet. Such groups can overload the policy-making process and frustrate depoliticisation. Debates about the constitution and governance have largely ignored these issues and there is need for a debate

Measurement of neutron capture on 48^{48}Ca at thermal and thermonuclear energies

At the Karlsruhe pulsed 3.75\,MV Van de Graaff accelerator the thermonuclear $^{48}$Ca(n,$\gamma$)$^{49}$Ca(8.72\,min) cross section was measured by the fast cyclic activation technique via the 3084.5\,keV $\gamma$-ray line of the $^{49}$Ca-decay. Samples of CaCO$_3$ enriched in $^{48}$Ca by 77.87\,\% were irradiated between two gold foils which served as capture standards. The capture cross-section was measured at the neutron energies 25, 151, 176, and 218\,keV, respectively. Additionally, the thermal capture cross-section was measured at the reactor BR1 in Mol, Belgium, via the prompt and decay $\gamma$-ray lines using the same target material. The $^{48}$Ca(n,$\gamma$)$^{49}$Ca cross-section in the thermonuclear and thermal energy range has been calculated using the direct-capture model combined with folding potentials. The potential strengths are adjusted to the scattering length and the binding energies of the final states in $^{49}$Ca. The small coherent elastic cross section of $^{48}$Ca+n is explained through the nuclear Ramsauer effect. Spectroscopic factors of $^{49}$Ca have been extracted from the thermal capture cross-section with better accuracy than from a recent (d,p) experiment. Within the uncertainties both results are in agreement. The non-resonant thermal and thermonuclear experimental data for this reaction can be reproduced using the direct-capture model. A possible interference with a resonant contribution is discussed. The neutron spectroscopic factors of $^{49}$Ca determined from shell-model calculations are compared with the values extracted from the experimental cross sections for $^{48}$Ca(d,p)$^{49}$Ca and $^{48}$Ca(n,$\gamma$)$^{49}$Ca.Comment: 15 pages (uses Revtex), 7 postscript figures (uses psfig), accepted for publication in PRC, uuencoded tex-files and postscript-files also available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Ca.u

Dynamic reliability analysis using the extended support vector regression (X-SVR)

© 2019 Elsevier Ltd For engineering applications, the dynamic system responses can be significantly affected by uncertainties in the system parameters including material and geometric properties as well as by uncertainties in the excitations. The reliability of dynamic systems is widely evaluated based on the first-passage theory. To improve the computational efficiency, surrogate models are widely used to approximate the relationship between the system inputs and outputs. In this paper, a new machine learning based metamodel, namely the extended support vector regression (X-SVR), is proposed for the reliability analysis of dynamic systems via utilizing the first-passage theory. Furthermore, the capability of X-SVR is enhanced by a new kernel function developed from the vectorized Gegenbauer polynomial, especially for solving complex engineering problems. Through the proposed approach, the relationship between the extremum of the dynamic responses and the input uncertain parameters is approximated by training the X-SVR model such that the probability of failure can be efficiently predicted without using other computational tools for numerical analysis, such as the finite element analysis (FEM). The feasibility and performance of the proposed surrogate model in dynamic reliability analysis is investigated by comparing it with the conventional ε-insensitive support vector regression (ε-SVR) with Gaussian kernel and Monte Carlo simulation (MSC). Four numerical examples are adopted to evidently demonstrate the practicability and efficiency of the proposed X-SVR method