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Deep geothermal drilling is a necessary technological stage to produce renewable energy by "enhanced geothermal systems" everywhere. However, the high cost and complexity of deep drilling through hard rock formations is a major barrier to its commercialization. One approach to reach affordability and reduce the cost of deep drilling is to use millimeter-wave (mmw) gyrotron radiation to melt or vaporize rocks. In this paper, the results of an experimental study of mmw radiation absorption by hard rocks are presented. Electromagnetic attenuation and reflection were measured in W-band at frequencies from 75 to 110 GHz in eight rock samples from six different geological formations originated in Israel. The results show that the mmw radiation absorption in hard rocks ranges from 90 to 99% per centimeter. The absorption varies slightly with rock type and is relatively independent of frequency but has reached higher values at the upper W band for all samples. The study suggests that high-power mmw radiation is a promising technology for deep geothermal drilling. The results of this experiment, attenuation, and reflection of W-band radiation in hard rocks provide valuable information for the design and optimization of mmw-based drilling systems, and will support the design and optimization of gyrotron based hard rock drilling equipment for geothermal applications. [ABSTRACT FROM AUTHOR]

Titanium and its alloy are materials that attract great interest due to mechanical properties, such as density, mechanical strength, and others. Titanium has been demonstrated as an excellent material to be used as a biomaterial. The field of biomaterials, mainly in prostheses, has continuously increased due to the high demand for people with injuries due to accidents or ageing. However, manufacturing these materials requires great care due to the difficulties on the surface to produce good osseointegration. Among the several machining processes, drilling is the most popular process in the manufacturing sector. Nevertheless, the drilling has serious challenges, mainly for the titanium and its alloys. The present work developed experimental and numerical tests of deep drilling in the Ti-6Al-4 V ELI titanium alloy, analysing the cutting forces, geometric tolerance, and temperature. The finite element method using a 3D numeric model was applied to predict the outcomes, and experimental tests were carried out with solid carbide helical drills to confirm the results. The results indicated that using high feed could be a great alternative in drilling Ti-6Al-4 V ELI. This technique can improve productivity and attend to the demands in the biomaterials area within certain tolerance classes. [ABSTRACT FROM AUTHOR]

In this study, the spatial variability of nitrogen (N) balances and potential nitrate leaching were determined in heterogeneous arable fields in southern Germany using digital methods (tractor-mounted multispectral sensor, satellite data, vegetation indices and models) and measurements of nitrate stocks in deeper zones (1−2.5 m soil depth) with deep drilling. The aim of this study was to achieve precise localisation of N losses at high spatial resolution (sub field level; 10 × 10 m grid). The spatial variability of plant parameters within uniformly fertilised fields (crop yield, N uptake) was determined for the calculation of the N balances. The spatial variability of soil properties (e.g. soil organic carbon content, soil total nitrogen content) were determined to identify the causes of high or low N surpluses and nitrate leaching in sub-fields. N surplus determined using different digital methods and measured nitrate stocks showed similar spatial patterns. Site-specific N balancing identified zones with high N loss potential (N surplus up to 86 kg ha−1). Deep drilling showed zones with high nitrate loss (nitrate N up to 94 kg ha−1). N surplus and nitrate loss correlated with r = 0.49. This relationship could be impacted by many other soil and management factors. Soil properties showed considerable spatial variation within the fields. Soil organic carbon (SOC) and soil total nitrogen (TN) content were closely correlated in all fields (up to r = 0.96) and were most closely positively correlated with crop yield and N uptake (up to r = 0.74) and negatively correlated with N surplus (up to r = − 0.73). The sensor data and satellite data (crop yield, N uptake, N surplus) showed similar distribution patterns. Based on these results, digital technologies are suitable for the calculation of site-specific N surplus and estimation of nitrate leaching risk. Satellite or sensor based site-specific and yield-oriented fertilization is one approach to reduce N surplus on sub fields with low yield potential and high nitrate leaching risk. [ABSTRACT FROM AUTHOR]

The machining of a deep hole by a gun drill is considered, both theoretically and experimentally. The cutting zone is divided notionally into 20 annular layers, for each of which the cutting parameters are calculated by successive approximation. A formula permits estimation of the cutter's wear facet, taking account of the energy consumed, the tool parameters, and the machining time. [ABSTRACT FROM AUTHOR]

A technology of producing hollow railroad axles by screw piercing and radial forging is developed. The design of hollow axles and the production technology are described. The sequence of piercing and forging operations is presented. Trial rough axles were produced. Their mechanical properties are tested, and the test results are compared to the requirements to solid axles. [ABSTRACT FROM AUTHOR]

An oil-based drilling fluid should be stable and tolerant to high temperatures for use in deep drilling. An invert emulsion of water in oil is a good choice as an oil-based drilling fluid which is a mixture of a solid phase and two immiscible liquid phases stabilized by a polymeric surfactant. In deep drilling, due to high temperatures, the polymeric surfactant degrades and a phase separation occurs. Here, octadecyltrimethoxysilane-modified silica nanoparticles were used to form a stable invert emulsion of water in oil for the drilling fluid model which resulted in a milky fluid with the formation of 60 µm water droplets. In addition, rheological study showed that using hydrophobic silica nanoparticles resulted in a stable water in oil invert emulsion with desired properties for a drilling fluid that can be modified by adjusting the nanoparticle nature and content. Aging experiments at 120 °C indicated that they also have good stability at high temperatures for challenging drilling operations. [ABSTRACT FROM AUTHOR]

Examples are presented to illustrate the high-speed drilling of small-diameter holes (up to 10 mm) by core flat drills: holes (diameter 7 mm) in a discharge valve; and the drilling two-part holes consisting of a cylindrical section (diameter 3.8 mm) and conical section (base diameter 10 mm) in a metal housing. [ABSTRACT FROM AUTHOR]

The demand for superhigh-precision austenitic fuel rods for fast-reactor piles increases every year. Accordingly, means of reducing the product cost without loss of quality-in particular, resistance to radiative swelling-are required. Optimization of the production process calls for the introduction of helical broaching and radial forging instead of deep drilling, with the necessary auxiliary processes. [ABSTRACT FROM AUTHOR]

A soft computing system used to optimize deep drilling operations under high-speed conditions in the manufacture of steel components is presented. The input data includes cutting parameters and axial cutting force obtained from the power consumption of the feed motor of the milling centres. Two different coolant strategies are tested: traditional working fluid and Minimum Quantity Lubrication (MQL). The model is constructed in three phases. First, a new strategy is proposed to evaluate and complete the set of available measurements. The primary objective of this phase is to decide whether further drilling experiments are required to develop an accurate roughness prediction model. An important aspect of the proposed strategy is the imputation of missing data, which is used to fully exploit both complete and incomplete measurements. The proposed imputation algorithm is based on a genetic algorithm and aims to improve prediction accuracy. In the second phase, a bag of multilayer perceptrons is used to model the impact of deep drilling settings on borehole roughness. Finally, this model is supplied with the borehole dimensions, coolant option and expected axial force to develop a 3D surface showing the expected borehole roughness as a function of drilling process settings. This plot is the necessary output of the model for its use under real workshop conditions. The proposed system is capable of approximating the optimal model used to control deep drilling tasks on steel components for industrial use. [ABSTRACT FROM AUTHOR]

A predictive model is presented to optimize deep drilling operations under high speed conditions for the manufacture of steel components such as moulds and dies. The input data include cutting parameters and axial cutting forces measured by sensors on the milling centres where the tests are performed. The novelty of the paper lies in the use of Bayesian Networks that consider the cooling system as an input variable for the optimization of roughness quality in deep drilling operations. Two different coolant strategies are tested: traditional working fluid and MQL (Minimum Quantity Lubrication). The model is based on a machine learning classification method known as Bayesian networks. Various measures used to assess the model demonstrate its suitability to control this type of industrial task. Its ease of interpretation is a further advantage in comparison with other artificial intelligence tools, which makes it a user-friendly application for machine operators. [ABSTRACT FROM AUTHOR]

Corrosion fatigue (CF), hydrogen induced cracking (HIC) and sulfide stress cracking (SSC), or environmentally assisted cracking (EAC) have been identified as the most challenging causes of catastrophic brittle fracture of drill pipes during drilling operations of deep oil and natural gas wells. Although corrosion rates can be low and tensile stresses during service can be below the material yield stress, a simultaneous action between the stress and corrosive environment can cause a sudden brittle failure of a drill component. Overall, EAC failure consists of two stages: incubation and propagation. Defects, such as pits, second-phase inclusions, etc., serve as preferential sites for the EAC failure during the incubation stage. Deep oil and gas well environments are rich in chlorides and dissolved hydrogen sulfide, which are extremely detrimental to steels used in drilling operations. This article discusses catastrophic brittle fracture mechanisms due to EAC of drill pipe materials, and the corrosion challenges that need to be overcome for drilling ultra-deep oil and natural gas wells. [ABSTRACT FROM AUTHOR]

Several missions for planetary exploration, including comets and asteroids, are ongoing or planned by the European Space Agencies: Rosetta, Venus Express, Bepi Colombo, Dawn, Aurora and all Mars Programme (in its past and next missions) are good examples. The satisfaction of the scientific request for the mentioned programmes calls for the development of new instruments and facilities devoted to investigate the body (planet, asteroid or comet) both remotely and by in situ measurements. The paper is an overview of some instruments for remote sensing and in situ planetary exploration already developed or under study by Galileo Avionica Space & Electro-Optics B.U. (in the following shortened as Galileo Avionica) for both the Italian Space Agency (ASI) and for the European Space Agency (ESA). Main technologies and specifications are outlined; for more detailed information please refer to Galileo Avionica’s web-site at: . [ABSTRACT FROM AUTHOR]

Parameter identification of the mathematical model of spiral-drill wear in deep drilling is considered. Wear is simulated by piecewise-linear approximation of the growth of drag torque in drilling. The diagnostic index selected is the constant component of the drag torque after the onset of drilling. The significance of the diagnostic index in determining the wear is demonstrated. [ABSTRACT FROM AUTHOR]

The mechanical properties and failure mode of rock subjected to high temperature and high pressure are significantly different from those of normal temperature and pressure. Research of rock's failure criterion under HTHP has important guiding significance for deep drilling and fracturing security. Considering the high temperature and pressure geological environment in deep tight sandstone reservoirs in Qaidam Basin, triaxial tests of rock obtained from deep sandstone reservoir under five groups of different temperatures (20 °C, 80 °C, 120 °C, 140 °C, 160 °C) are performed by RTR-1500 electro-hydraulic and servo-controlled Rock Triaxial Testing System. The results from the tests show that, in the experimental temperature range, the cohesion and internal friction coefficient of the rock decreases with the increase of temperature, the relationship between cohesion and temperature is cubic polynomial, and the internal friction coefficient is also cubic nonlinearly correlated with temperature; along with the increase of temperature, the compressive strength of rock under the same confining pressure gradually decreases, and the compressive strength of rock in different confining pressures tends to be the same. Based on the analysis of data from triaxial tests under different temperatures and the principle of Mohr-Coulomb criterion, the specific expression of the failure criterion for tight sandstone under the coupling effects of temperature and pressure is formulated. This criterion can truly reflect the change rules of sandstone strength with temperature and pressure and can also be used to predict the failure strength under different temperatures and pressures conveniently and easily. [ABSTRACT FROM AUTHOR]