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A long milling tool with a hollow shank is considered. A special chamber in the shank accommodates the compensation material. This design ensures that the tool is self-balancing. That reduces its vibrational amplitude and increases the productivity in high-speed machining.
The mechatronic system of the DUO-300 rolling mill is analyzed. The influence of the roller’s linear velocity on the distribution of frictional forces in the rolling region is studied. A nonlinear relation is found between the load and the roller speed. The conditions of self-oscillation in rolling are determined. Methods of damping the self-oscillation are considered.
The production of small complex components by electric-discharge milling is studied by experimental methods. Means of optimizing numerical-control software so as to obtain the required shaping precision are proposed. The proposed systems and equipment permit the development and implementation of designs unattainable by other means.
For many years, the structure of milling and drilling machines has remained basically the same: the spindle chuck is attached in cantilever fashion to the vertical column. In the present work, a new configuration is considered.
The temperature rise in the cutting zone during high-speed milling is considered. A method of calculating this temperature rise is proposed.
The influence of cutting (milling) on the surface roughness and undulation of AMg2 aluminum alloy with regular and ultrafine grain structure is considered. In the machining of materials with ultrafine grain structure, the surface quality is better than for materials with regular grain structure.
A control method is proposed for bulk milling on CNC machines. A method is described for determining the supply corresponding to specified machining accuracy.
Abstract—Analysis of drilling methods and drilling tools used in the oil and gas industry gives rise to a new dual-action drilling and milling tool, which ensures constant contact of the tool’s cutting edge with the face. That reduces the frictional forces in drilling and improves the tool’s wear resistance.
Random thickness variations in chemically milled aluminum alloy
Digital computer prototype for use in automatic control program for machining on a milling machine
Nonuniform stock removal, quenching rate, cold working, hardness, and aging factors affect on chemical milling characteristics of aluminum alloys
Manmade chemical and radioactive contamination of groundwater is one of damaging effects of the uranium mining and milling facilities. Groundwater contamination is of special importance for the area of Priargun Production Mining and Chemical Association, JSC 'PPMCA', because groundwater is the only source of drinking water. The paper describes natural conditions of the site, provides information on changes of near-surface area since the beginning of the company, illustrates the main trends of contaminators migration and assesses manmade impact on the quality and mode of near-surface and ground waters. The paper also provides the results of chemical and radioactive measurements in groundwater at various distances from the sources of manmade contamination to the drinking water supply areas. We show that development of deposits, mine water discharge, leakages from tailing dams and cinder storage facility changed general hydro-chemical balance of the area, contributed to new (overlaid) aureoles and flows of scattering paragenetic uranium elements, which are much smaller in comparison with natural ones. However, increasing flow of groundwater stream at the mouth of Sukhoi Urulyungui due to technological water infiltration, mixing of natural water with filtration streams from industrial reservoirs and sites, containing elevated (relative to natural background) levels of sulfate-, hydro-carbonate and carbonate- ions, led to the development and moving of the uranium contamination aureole from the undeveloped field 'Polevoye' to the water inlet area. The aureole front crossed the southern border of water inlet of drinking purpose. The qualitative composition of groundwater, especially in the southern part of water inlet, steadily changes for the worse. The current Russian intervention levels of gross alpha activity and of some natural radionuclides including {sup 222}Rn are in excess in drinking water; regulations for fluorine and manganese concentrations are also in excess. Possible ways to improve the situation are considered. (authors)
Increased purity in uranium ore concentrate not only raises the question as to whether Safeguards should be applied to the entirety of uranium conversion facilities, but also as to whether some degree of coverage should be moved back to uranium ore concentrate production at uranium mining and milling facilities. This paper looks at uranium ore concentrate production across the globe and explores the extent to which increased purity is evident and the underlying reasons. Potential issues this increase in purity raises for IAEA's strategy on the Starting Point of Safeguards are also discussed.
Radon (Rn) fluxes were measured at a disposal facility for uranium mill tailings after two decades of service. The facility was closed with an earthen cover vegetated with grasses. Measurements were made on the surface of the Rn barrier and directly on the surface of the tailings. Fluxes were measured using extra small (area = 0.018 m{sup 2}), small (0.071 m{sup 2}), medium (0.59 m{sup 2}), and large (2.32 m{sup 2}) flux chambers to evaluate the impact of measurement scale on Rn flux. Activated carbon (AC) passive collectors and electric radon detectors (RAD7) were used to measure Rn concentrations. Tests were conducted at various locations on each cover representing conditions that can lead to different levels of soil structural development and different water content. Rn fluxes at the surface of the Rn barrier were much lower than Rn fluxes measured at the surface of the tailings, indicating the barrier remained effective for Rn containment. Geometric mean Rn fluxes measured at the surface of the Rn barrier in each test pit were below the regulatory requirement (0.74 Bq/m{sup 2}- s). Rn concentrations measured using AC samplers in the flux chambers were 60% of concentrations measured using the RAD7, on average, and Rn fluxes computed with the AC data were 9% of those computed with the RAD7 data, on average. Size of the flux chamber had no systematic effect on Rn flux, indicating that 20 y of soil forming processes had not created a pore network causing scale-dependent Rn flux. Geometric mean Rn fluxes in the test pits were similar regardless of differences in surface conditions (vegetation, thickness of soil cover) known to influence soil forming processes and soil structure, but were lower in areas where surface conditions promoted higher water content in the Rn barrier. (authors)
exploitation activities took place at 61 sites. The great majority of these mining sites are located in central-east Portugal, including the Urgeirica mine that was the most important uranium deposit exploited in the country. The mining activities at this site generated 1.6 million m{sup 3} of radioactive wastes disposed in an open air area originating the largest radioactive tailings pile of the country. The environmental remediation of the Urgeirica site was one of the main priorities of the national plan for the rehabilitation of former uranium mining sites. Site remediation, that included the mine industrial area with several support infrastructures and a processing plant, was executed between 2006 and 2008 (1. phase) and between 2008 and 2014 (2. phase). Nevertheless, the environmental rehabilitation of the Portuguese uranium legacies sites is not yet concluded. One of the last largest mining complexes, the Quinta do Bispo open pit, is scheduled to be rehabilitated only in 2020. This work presents a study to evaluate the environmental impacts from the uranium mill tailings legacies before and after the remediation works, focusing on two different approaches: a deterministic methodology for dose assessment and a probabilistic methodology with the Monte Carlo method to estimate the incremental lifetime risk. Probabilistic distributions of the input parameters were used in the risk calculation approach. The methodology for dose and risk assessments may be applied to other sites that are still under intervention and the results may be used to prioritize the remediation stages. (authors)
The quality and specific energy consumption (SEC) of the biomass pellets produced depend upon pelleting process conditions. The present study includes understanding the effect of feedstock moisture in the range of 28–38% (wet basis [w.b.]) and preheating in the range of 30–110°C at two die speeds of 40 and 60 Hz on the physical properties and SEC. A flat die pellet mill fitted with a 6 mm die was used in the present study. The physical properties of pellets such as moisture content, unit, bulk and tapped density, durability, and expansion ratio and SEC of the pelleting process are measured. The results indicate that the pellets produced have durability values in the range of 87–98%, and unit bulk and tapped density in the range of 670–1100, 375–575, and 420–620 kg/m³. Increasing the feedstock moisture content from 33% to 38% (w.b) decreased the unit, bulk and tapped density by about 30–40%. Increasing feedstock moisture content increased the expansion ratio and decreased the density values. A higher feedstock moisture content of 38% (w.b.) and higher preheating temperature of 110°C resulted in lower density and a higher expansion ratio, which can be attributed to flash off of moisture as the material extrudes out of the die. The SEC was in the range of 75–275 kWh/ton. Higher feedstock moisture content of 38% (w.b.) and a lower die speed of 40 Hz increased the SEC, whereas lower to medium preheating temperature (30–70°C), medium feedstock moisture content of 33% (w.b.), and a higher die speed of 60 Hz minimized the SEC to <100 kWh/ton.
We perform microcanonical classical statistical lattice simulations of SU(N) Yang-Mills theory with eight scalars on a circle. Measuring the eigenvalue distribution of the spatial Wilson loop we find two distinct phases depending on the total energy and circle radius, which we tentatively interpret as corresponding to black hole and black string phases in a dual gravity picture. We proceed to study quenches by first preparing the system in one phase, rapidly changing the total energy, and monitoring the real-time system response. We observe that the system relaxes to the equilibrium phase corresponding to the new energy, in the process exhibiting characteristic damped oscillations. We interpret this as the topology change from black hole to black string configurations, with damped oscillations corresponding to quasi-normal mode ringing of the black hole/black string final state. This would suggest that α′ corrections alone can resolve the singularity associated with the topology change. We extract the real and imaginary part of the lowest-lying presumptive quasinormal mode as a function of energy and N.
We obtain a conservative Hamiltonian describing the interactions of two charged bodies in Yang-Mills through $\mathcal{O}$ (α 2 ) and to all orders in velocity. Our calculation extends a recently-introduced framework based on scattering amplitudes and effective field theory (EFT) to consider color-charged objects. These results are checked against the direct integration of the observables in the Kosower-Maybee-O’Connell (KMOC) formalism. At the order we consider we find that the linear and color impulses in a scattering event can be concisely described in terms of the eikonal phase, thus extending the domain of applicability of a formula originally proposed in the context of spinning particles.