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With the high-intensity mining activities and the selection of interval mining methods, a large amount of high-rank coal resources are left in the underground space (isolated islands). However, due to the complicated mining geological conditions, the coal resources in the isolated islands have not been fully extracted. In this paper, the mechanism of water inrush from limestone aquifers under isolated island panels is discussed from theoretical mechanics analysis, numerical simulation, discriminant criterion, the variation law of surrounding rock stress and water pressure, and floor failure depth. Meanwhile, we take the coal mining of the isolated island shaft in the Zhuzhuang colliery, Huaibei mining area, as an application case and propose the key technique of limestone water disaster prevention and control. Eventually, the treatment effect is validated by the practical work. The study results indicate that (1) the depth of the floor failure zone is 27.51 m and that the risk owing to water inrush of the panel floor in the isolated islands exists. The isolated coal pillar is more affected by the formation stress in numerical simulation, and the distribution of small stress on both sides of the panel floor and large stress in the middle area formed compared to non-isolated islands. The maximum stress of the panel floor is greater than that of mining without isolated islands. (2) The special drilling structures, stepwise gradient pressurization, and segmented sequential downward grouting technique are proposed to ensure the grouting effect under goaf. (3) Finally, the limestone water disaster regional treatment and control for the isolated island shaft is carried out and validated. The water level of ground boreholes and the water yield of underground directional boreholes verified the treatment effect. The theoretical results and engineering application in this study have significant implications for coal mining on other isolated islands affected by panel floor water damage. [ABSTRACT FROM AUTHOR]

With the high-intensity mining activities and the selection of interval mining methods, a large amount of high-rank coal resources are left in the underground space (isolated islands). However, due to the complicated mining geological conditions, the coal resources in the isolated islands have not been fully extracted. In this paper, the mechanism of water inrush from limestone aquifers under isolated island panels is discussed from theoretical mechanics analysis, numerical simulation, discriminant criterion, the variation law of surrounding rock stress and water pressure, and floor failure depth. Meanwhile, we take the coal mining of the isolated island shaft in the Zhuzhuang colliery, Huaibei mining area, as an application case and propose the key technique of limestone water disaster prevention and control. Eventually, the treatment effect is validated by the practical work. The study results indicate that (1) the depth of the floor failure zone is 27.51 m and that the risk owing to water inrush of the panel floor in the isolated islands exists. The isolated coal pillar is more affected by the formation stress in numerical simulation, and the distribution of small stress on both sides of the panel floor and large stress in the middle area formed compared to non-isolated islands. The maximum stress of the panel floor is greater than that of mining without isolated islands. (2) The special drilling structures, stepwise gradient pressurization, and segmented sequential downward grouting technique are proposed to ensure the grouting effect under goaf. (3) Finally, the limestone water disaster regional treatment and control for the isolated island shaft is carried out and validated. The water level of ground boreholes and the water yield of underground directional boreholes verified the treatment effect. The theoretical results and engineering application in this study have significant implications for coal mining on other isolated islands affected by panel floor water damage.

The Hangzhou Bay Sea-Crossing Bridge for the Nantong-Suzhou-Jiaxing-Ningbo Railway will be the longest seacrossing high-speed railway bridge with the highest construction standards in the world after its completion. The construction conditions in this area are harsh, and the borehole depth is great, demanding higher verticality. In order to ensure the engineering quality, the "dynamic to static" coupling dual platform independently developed by CCCC Third Harbor Consultants Co.,Ltd. is adopted, and it can effectively reduce the impact of surge waves on the stability of the exploration platform and the deviation of the opening of boreholes. SH-G3 borehole trajectory detector is used to detect the verticality of the boreholes. By comparing the testing results of borehole verticality by different drilling techniques, the influencing factors on drilling verticality in offshore exploration are analyzed. The results showed that, regardless of the geological factors, when a drilling rig adopts integrated drilling technique such as medium-speed gear drilling, ø50 mm drilling rods and longer coring sampler, the drilling deflection may be greatly reduced and the borehole verticality may be much improved in offshore exploration, providing more accurate survey results for engineering construction projects. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the necessity and effectiveness of a preplanned technique for drilling during transcanal endoscopic ear surgery. Methods: Study design: Retrospective case series study from June 2011 to June 2015. Setting: Private tertiary care hospital. Patients: Eighty-five ears of 78 patients, age ranging from 9 to 57 years underwent transcanal endoscopic drilling for various types of pathology in their middle and external ear. Interventions: Application of a preplanned technique for transcanal drilling in endoscopic ear surgery that involved short timed drilling with use of intermittent irrigation and suction. Every events of the procedure were done one after another with the single hand of the surgeon. An attachment providing protecting sheath around rotating burr was used during each time of drilling. Main outcomes measure: Efficacy of such drilling technique in single handed endoscopic ear surgery. Presence of any postoperative thermal injury of facial nerve and any lacerated injury of skin of external ear. Results: This preplanned technique was found suitable for transcanal endoscopic drilling with the single hand of the surgeon. Postoperative facial nerve palsy or laceration of skin of external ear was not noted in any patient. Conclusion: After using the present technique, transcanal endoscopic drilling could be done easily and safely with single hand of the surgeon.

Securing energy means grasping the key link in the national development and security strategy. Under the goals of carbon peak and carbon neutrality, the overall tendency of energy development is to increase the proportion of natural gas while stabilizing oil consumption, and the global primary energy is entering the era of natural gas. Gas hydrate in deep seabed shallow strata and extremely cold permafrost regions has piqued the interest of researchers due to its abundant resources, widespread distribution, and high energy density. Although the drilling of hydrate wells is still fraught with unknowns and challenges due to the technological barriers between countries, complex on-site working conditions, and unique physical chemical properties, accumulation forms, and occurrence characteristics of gas hydrate, more than ten successful trial productions around the world have opened the door of hope for the development of this potentially new energy. The gas hydrate reservoir drilling technique is the frontier and hotspot of scientific and technological innovation and competitiveness around the globe today, reflecting the level of oil and gas technical advancement. At the national level, it possesses strategic and revolutionary features. Innovative drilling techniques, scientific well location layout, appropriate wellbore structure and well trajectory design, efficient drilling fluid, qualified drilling and completion equipment, and successful pressure-temperature preserved coring may all provide a strong guarantee for the successful completion of gas hydrate wells. This review comprehensively reviews the drilling techniques and engineering measures that can be used to develop gas hydrate. It focuses on the research advancement of important hydrate drilling technologies and the enlightening significance of these developments in the application of hydrate drilling. This work will deliver valuable experience as well as comprehensive scientific information for gas hydrate exploration and drilling.

Based on the example of goaf water drainage in the main transportation roadway of Hanzui Coal Mine, the formation of goaf water in the main transportation roadway is deeply analyzed. The conventional borehole B5 with the largest water inflow is selected as the target. It is suggested that the goaf water should be drained by a long directional borehole with long downward slope and upward elevation. The results show that the downward inclined and upward directional long borehole is suitable for long distance drainage of goaf water, and the drilling trajectory is designed as casing section, straight hole section, inclined section, stable inclined section, inclined section and stable inclined section, which can realize large angle oblique penetration through the old empty area. And avoiding the formation of drainage grooves, adopting directional drilling technology of clear water medium to ensure the straightness of casing section, stable directional drilling can be realized in 2 m to 7 m sand and mudstone interbedding below coal floor, and rotary drilling tool assembly is adopted. With the parameters of low drilling pressure and low torque, the smooth drilling in the old empty area can be realized, and finally the target area can be successfully drilled, and the good achievement of drilling 17 m in the old empty area and water inflow up to 134 m3/h after drilling can be realized. A total of 36 000 m3 of goaf water was released.

The side effects from the use of plant protection products and their potential effects on non-target arthropods (NTAs) such as honey bees, other insects within the vegetation layer and epigeic arthropods nowadays receive more attention. However, uncertainties about the factors driving the deposition of active substances (a.s.) into off-crop areas persist, in particular during sowing of treated seeds. Analysing a highly standardised 8-year field experiment, we assessed the importance of various factors potentially affecting dust drift and deposition of a.s., emitted during the sowing process of treated seeds and deposited on fields adjacent to the drilling field, i.e. on the ground, on flowers, and on nonflowering plant parts. Regarding a.s. deposition, the Heubach a.s. value has a predictive capability, which is independent from all other factors taken into account in this study, and can thus be considered as a scenario-independent measure of potential dust deposition. Petri dish samplers, an established standard method for measuring a.s. deposition, were representative of the results from the plant samplers for a given combination of drilling technique and adjacent crop type. Adjacent crop type is likely to impact on a.s. deposition. The present work will enable a more field-realistic exposure assessment for bees and other NTAs. [ABSTRACT FROM AUTHOR]

Copyright of Turkish Studies - Social Sciences is the property of Electronic Turkish Studies and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The relevance of the research is caused by the necessity of improving the engineering and technology of geological explorations and the energy and resource efficiency of drilling. The main aim of the research is to analyse and generalize research results obtained for the possible development and application of the resource-efficient drilling technology using the strain wave generator. The literature review of theoretical and experimental research was carried out in percussion drilling of small holes in medium-hard and harder rocks. To increase the penetration rate, the percussive mechanisms were designed. However, the increase of strain wave energy is reduced by the strength of the drilling tool. At constant hole diameter, the increased impact load should be transmitted over the drill string and their connections having the original size. These very elements of a drill string are the deterrents to implement a new technology. Methodology: theoretical analysis; a vast review of scientific literature on all problems of power pulse formation, strain wave transmission over the drill string, rock failure, appropriate modes of operation of percussion drilling, drilling optimization prior the engineering process, design techniques chosen for percussion drilling systems, work process modeling, energy parameter determination for drilling units, comparison of independent research results Findings. The paper introduces the modern ideas and achievements in the field of small hole percussion drilling. The authors have identified the causes of research results divergence. The expediency of carrying out the research to improve technological and engineering processes and drilling techniques was shown. The authors determined the main trends in researching drilling technology and engineering process and stated the recommendations for improving drilling effectiveness due to intensification of rock failure at well boring.

Heat generation during insertion of Kirschner wires (K‐wires) may lead to thermal osteonecrosis and can affect the construct fixation. Unidirectional and oscillatory drilling modes are options for K‐wire insertion, but understanding of the difference in heat generation between the two modes is lacking. The goal of this study was to compare the temperature rise during K‐wire insertion under these two modes and provide technical guidelines for K‐wire placement to minimize thermal injury. Ten orthopedic surgeons were instructed to drill holes on hydrated ex vivo bovine bones under two modes. The drilling trials were evaluated in terms of temperature, thrust force, torque, drilling time, and tool wear. The analysis of variance showed that the oscillatory mode generated significantly lowered peak bone temperature rise (13% lower mean value, p = 0.036) over significantly longer drilling time (46% higher mean time, p < 0.001) than the unidirectional mode. Drilling time had significant effect on peak bone temperature rise under both modes (p < 0.001) and impact of peak thrust force was significant under oscillatory mode (p < 0.001). These findings suggest that the drilling mode choice is a compromise between peak temperature and bone exposure time. Shortening the drilling time was the key under both modes to minimize temperature rise and thermal necrosis risk. To achieve faster drilling, technique analysis found that "shaky" and intermittent drilling with moderate thrust force are preferred techniques by small vibration of the drill about the K‐wire axis and slight lift‐up of the K‐wire once or twice during drilling. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1903–1909, 2019 [ABSTRACT FROM AUTHOR]

In this paper, we develop and put into practice an automatic optical inspection (AOI) system based on machine vision to check the holes on a printed circuit board (PCB). We incorporate the hardware and software. For the hardware part, we combine a PC, the three-axis positioning system, a lighting device, and charge-coupled device cameras. For the software part, we utilize image registration, image segmentation, drill numbering, drill contrast, and defect displays to achieve this system. Results indicated that an accuracy of 5 μm could be achieved in errors of the PCB holes allowing comparisons to be made. This is significant in inspecting the missing, the multi-hole, and the incorrect location of the holes. However, previous work only focuses on one or other feature of the holes. Our research is able to assess multiple features: missing holes, incorrectly located holes, and excessive holes. Equally, our results could be displayed as a bar chart and target plot. This has not been achieved before. These displays help users to analyze the causes of errors and immediately correct the problems. In addition, this AOI system is valuable for checking a large number of holes and finding out the defective ones on a PCB. Meanwhile, we apply a 0.1-mm image resolution, which is better than others used in industry. We set a detecting standard based on 2-mm diameter of circles to diagnose the quality of the holes within 10 s.

Due to the increasing depths of coal mines and the low permeability of some coal seams, conventional methods of gas drainage in underground mines are facing many problems. To improve gas extraction, a new technique using water jets to drill tree-type boreholes in coal seams is proposed. A self-propelled water-jet drilling nozzle was designed to drill these boreholes. The configuration of the self-propelled nozzle was optimized by conducting drilling experiments and self-propelling force measurements. Experimental results show that the optimal self-propelled nozzle has a forward orifice axial angle at 25°, a radial angle at 90°, a center distance of 1.5 mm, and backward pointing orifices with an axial angle of 25°. The self-propelling force generated by the jets of the nozzle with 30 MPa pump pressure can reach 29.8 N, enough to pull the hose and the nozzle forward without any external forces. The nozzle can drill at speeds up to 41.5 m/h with pump pressures at 30 MPa. The radial angles of the forward orifices improve the rock breaking performance of the nozzle and, with the correct angle, the rock breaking area of the orifices overlap to produce a connecting hole. The diameter of boreholes drilled by this nozzle can reach 35.2 mm. The nozzle design can be used as the basis for designing other self-propelled nozzles. The drilling experiments demonstrate the feasibility of using the tree-type drilling technique in underground mines.

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: There are different techniques for drilling the femoral tunnel in the anterior cruciate ligament reconstruction (ACLR), but their influence in the bone tunnel enlargement in unknown. The purpose of this study was to compare two different surgical techniques for evaluating femoral tunnel enlargement in ACLR. The hypothesis was that tunnel placement using the outside-in technique leads to less tunnel enlargement compared to the transtibial technique. Methods: Forty-four patients treated for ACLR between March 2013 and March 2014 were prospectively enrolled in this study. According to the surgical technique, subjects were assigned to Group A (Out-in) or Group B (Transtibial). All patients underwent CT examination in order to evaluate the femoral tunnel enlargement at four different levels. Moreover, all patients were evaluated with the Lachman test and pivot shift test, and the KT1000 arthrometer was used to measure the anterior laxity of the knee. A subjective evaluation was performed using the 2000 International Knee Documentation Committee Subjective Knee score, Lysholm knee score and Tegner activity scale. All patients were assessed after 24 months of follow-up. Results: At the final follow-up, there were statistically significant differences ( p < 0.05) in femoral tunnel enlargement between the two groups at all four femoral levels in favor of the out-in group. No statistical significant differences were found in the objective and subjective clinical outcomes between the two groups ( p > 0.05). Conclusions: In ACLR with a suspension system, the outside-in technique leads to less enlargement of the femoral tunnel lower than the transtibial technique. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an important geothermal resource, hot dry rock (HDR) reserves have been studied in many countries. HDR resources in China have huge capacity and have become one of the most important resources for the potential replacement of fossil fuels. However, HDR resources are difficult to develop and utilise. Technologies for use with HDR, such as high-temperature drilling, reservoir characterisation, reservoir fracturing, microseismic monitoring and high-temperature power stations, originate from the field of oil and drilling. Addressing how to take advantage of these developed technologies is a key factor in the development of HDR reserves. Based on the thermal crustal structure in China, HDR resources can be divided into four types: high radioactive heat production, sedimentary basin, modern volcano and the inner-plate active tectonic belt. The prospective regions of HDR resources are located in South Tibet, West Yunnan, the southeast coast of China, Bohai Rim, Songliao Basin and Guanzhong Basin. The related essential technologies are relatively mature, and the prospect of HDR power generation is promising. Therefore, analysing the formation mechanisms of HDR resources and promoting the transformation of technological achievements, large-scale development and the utilisation of HDR resources can be achieved in China. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rezultati dobiveni u postupcima makroskopske i niza paleoradioloških analiza lubanje pokojnika sa srednjovjekovnoga groblja Zvonimirovo (sjeverna Hrvatska) potvrdili su nazočnost, po svemu sudeći, jedinstvene infratentorijalne (mastoidne) trepanacije koja datira u 11. stoljeće (Boljunčić, Hat 2015; Boljunčić 2016b). Riječ je, nedvojbeno, o vrijednom koštanom i CT dokazu o sofisticiranoj, čak složenoj (terapeutski indiciranoj) ante mortem trepanaciji na mastoidu desne sljepoočne kosti, tehnikom bušenja (Boljunčić 2016b). Koliko je poznato, u europskoj bioarheologiji još uvijek nisu opisani slični slučajevi trepanacija na mastoidu, kao ni drugi slučajevi infratentorijalnih trepanacija, koji bi datirali u srednji vijek, i šire. Predmetna istraživanja načinjena su, između ostaloga, u okviru teme „Primjena računalne tomografije (CT) u analizi bioarheoloških uzoraka“ u sklopu „Strategije“ Instituta za arheologiju (Zagreb). Sljedeći je cilj istraživanja daljnja rekonstrukcija „identiteta“, odnosno prepoznatljivosti zajednice čiji su se pokojnici ukapali u sklopu predmetnoga groblja - u kontekstu mogućega razvoja kirurških tehnika i postupaka tadašnjega vremena. Pritom će glavnina istraživanja biti usmjerena poglavito na moguće produbljivanje spoznaje o detaljima tehnike predmetne trepanacije i zahvaćenim anatomskim strukturama, primjenom novih metoda na temelju baze podataka dobivene u obradi pomoću računalne tomografije. To može pridonijeti stvaranju složenije slike o prepoznatljivosti i posebnostima povijesne zajednice s područja Zvonimirova. [ABSTRACT FROM AUTHOR]

Interactions between cementitious materials and claystone are driven by chemical gradients in pore water and might lead to mineralogical modifications in both materials. In the context of a radioactive waste repository, this alteration might influence safety-relevant clay properties like swelling pressure, permeability, or specific retention. In this study, interfaces of Opalinus Clay, a potential host-rock in Switzerland, and three concrete formulations emplaced in the Cement-Clay Interaction (CI) Experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) were analysed after 2.2 years of interaction. Sampling techniques with interface stabilisation followed by inclined intersection drilling were developed. Element distribution maps of the concrete-clay interfaces show complex zonations like sulphur enrichment, zones depleted in Ca but enriched in Mg, strong Mg enrichment adjacent to the interface, or carbonation. Consistently, the carbonated zone shows a reduced porosity. Properties of the complex zonation strongly depend on cement properties like water content and pH (ordinary Portland cement vs. low-pH cement). An increased Ca or Mg content in the first 100 µm next to the interface is observed in Opalinus Clay. The cation occupancy of clay exchanger phases next to the ordinary Portland cement interface is depleted in Mg, but enriched in Na, whereas porosity shows no changes at all. The current data suggests migration of CO2/HCO3-,SO4² and Mg species from clay into cement. pH decrease in the cement next to the interface leads to instability of ettringite, and the sulphate liberated diffuses towards higher pH regions (away from the interface), where additional ettringite can form. [ABSTRACT FROM AUTHOR]

Background: High-grade acromioclavicular (AC) joint separations require surgical treatment, as conservative treatment may result in functional decline or persistent pain. Although many surgical techniques have been described in the literature, there is still no non-controversial gold standard procedure for AC joint dislocation. The different orientation of the two components of the coracoclavicular (CC) ligaments has been proven to account for different functions. However, the majority of the techniques reconstruct the CC ligaments with a single structure. The purposes of this study were to assess the feasibility of truly anatomic coracoclavicular ligament reconstruction (TACCR) and to determine the corresponding drilling parameter. Methods: We constructed virtual three-dimensional (3D) models of 105 shoulders from computed tomography (CT) scan data by using SuperImage software. For each model, the attachment sites and footprint dimensions of the conoid and trapezoid ligaments were defined and adjusted according to previously defined anatomic parameters and individual measurement results. Virtual drilling and 3D measurement were carried out in each model separately. Guided by the drilling parameter, we performed TACCR on 24 shoulders from 12 whole cadavers after transecting the AC and CC ligaments. Results: The collinear drilling technique was noted to breach the bone cortex of the clavicle and/or the coracoid process in 95 of 105 virtual models (90.5%). No cortical breach was observed using a non-collinear drilling technique. The anteversion angulation of the conoid–coracoid tunnel ranged from 10° to 15° (mean value 12.4°). The extraversion angulation of the conoid–coracoid tunnel varied from 5° to 10° (mean value 6.8°). The anteversion angulation of the trapezoid–coracoid tunnel ranged from 20° to 30° (mean value 25.2°). There were no failures when performing the non-collinear drilling technique on cadaver models. Conclusions: The collinear drilling technique is not technically feasible for TACCR. For this reason, we recommend the non-collinear drilling technique, which provides the ability to prepare bony tunnels without any risk of cortical breach. Clinical relevance: Based on this computer and cadaver model study, we have devised a novel drilling technique to restore the CC ligaments anatomically. [ABSTRACT FROM AUTHOR]

To improve the heavy oil recovery of Lukexin Oilfield and decrease the composite development cost by horizontal well, and to realize oilfield highly efficient and economical development, a multi-lateral horizontal well was deployed in Tuha field, Well Yuping- 8. During the drilling process of the well, some technical difficulties were encountered, such as poor drillability of the formation, pending horizontal section sidetracking, original hole reentry, etc. Based on the analysis on the above difficulties, some corresponding techniques were used, like power drilling tool optimization and horizontal section pending sidetrack technique, and some techniques were improved, like advance drilling method of lateral well and original hole reentry by lateral well hole. As a result, the drilling period was effectively shortened, and the drilling safety and rate were guaranteed. The smooth drilling of Well Yuping-8 supplies a novel method for enlarge area control of heavy oil formation by drilling multi-lateral horizontal wells and greatly increase oil rate and oil recovery. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose: The aim of this prospective randomized controlled clinical study was to assess the crestal bone loss and the implant stability in implants that were placed by the osteotome technique compared with the conventional drilling technique. Materials and Methods: Forty-six screw type Straumann SLA® oral implants (Straumann AG, Waldenburg, Switzerland) were inserted in the anterior segment of maxilla of 30 patients. The implant site was prepared randomly using either osteotome technique (test group) or the conventional drilling technique (control group). Radio frequency analysis (RFA) values at implant placement and after 3 months were recorded. The crestal bone loss was measured using digital subtraction radiography technique after 3, 6, and 12 months. Results: RFA demonstrated a statistically significant higher primary stability for implants in the osteotome group than that of the conventional group ( p = .026) at the time of implant insertion. However, there was no statistically significant difference between both groups 3 months after the surgery ( p = .06). At month 3, the osteotome group caused significantly more crestal bone loss than the conventional group ( p = .04). At months 6 and 12, both groups had comparable bone levels ( p = .29). Conclusion: Osteotome technique yielded higher primary stability than conventional drilling technique. However, this technique was not superior to conventional technique after 3 months. [ABSTRACT FROM AUTHOR]

The incremental hole-drilling method is frequently used for residual stress depth distribution analyses, due to its fast and economical experimental execution. Depending on the planned use of the component, the drilled hole that is made to measure the residual stress can often be repaired or ignored if it does not affect the intended use of the part. Nevertheless an important experimental issue and assumption is the introduction of an ideal cylindrical hole into the component without additional plastic deformation. Although high-speed drilling is well established the consequences of the resulting hole geometries compared to ideal assumptions are not well known. Therefore, a detailed comparison between different bits and drilling techniques was carried out and is discussed in this paper in order to detect the best experimental conditions and to find out reasons especially for the lack of accuracy of the hole-drilling method for the first increments close to the specimens surface. It comes out that the orbital drilling with common used six-blade bits results in the best compromise of an ideal cylindrical hole and centricity to the center of the strain gage rosette. In the case of conventional drilling the hole geometry differs from the ideal one if six-blade bits were used due to the influence of chamfers at the cutting edges and a non 180° plane end face and also in the case of a two-blade bit due to a non 180° plane end face and the tendency to more eccentric holes. Diamond bits cannot be recommended under all tested conditions due to their geometrical undefined shape. [ABSTRACT FROM AUTHOR]

To more effectively promote the application of hydraulic pulse cavitating jet drilling technology (HPCJDT), many application cases of the HPCJDT have been summarized and analyzed based on the introduce of the mechanism of improving the rate of penetration with the HPCJDT. Results indicate that Hydraulic Pulsating-cavitating Jet Generator has the characteristics of simple structure, convenient application, and strong reliability. It could be used with conventional BHA, mud motor, under balanced drilling string and Power V drilling tool. This tool has been applied from Cenozoic formation to Paleozoic formation, and is suitable for either soft or hard formation. The maximum experimental well depth is up to 6 162 m, and the range of borehole diameter is from 215 mm to 406 mm, using different type PDC drill bit or cone bit. The applying range of drilling parameters is wide without special requirement. Usually, the tool could work over 230 h. The HPCJDT has well adaptability to the present drilling equipments, technological parameters, etc., and the average ROP has been increased by 10.1 to 104.4 percent, it provides a safe and high efficient novel drilling technology for deep drilling. [ABSTRACT FROM AUTHOR]

Background: Piezosurgery is based on microvibrations generated by the piezoelectrical effect and has a selective bone-cutting ability with preservation of soft tissue. This study examined the applicability of Piezosurgery compared to rotating drills (RD) for internal auditory canal (IAC) opening in acoustic neuroma (AN) surgery. Materials and methods: Piezosurgery was used in eight patients for IAC drilling in AN surgery. After exposition of the IAC and tumor, the posterior wall of the IAC was drilled using Piezosurgery instead of RD. Piezosurgery was evaluated with respect to practicability, safety, preciseness of bone cutting, preservation of cranial nerves, influences on neurophysiological monitoring, and facial nerve and hearing outcome. Results: Piezosurgery was successfully used for selective bone cutting, while cranial nerves were structurally and functionally preserved, which could be measured by means of neuromonitoring. Piezosurgery guaranteed a safe and precise cut by removing bone layer by layer in a shaping way. Compared to RD, limited influence on neurophysiological monitoring attributable to Piezosurgery was noted, allowing for continuous neuromonitoring. No disadvantage due to microvibrations was noticed concerning hearing function. The angled tip showed better handling in right-sided than in left-sided tumors in the hands of a right-handed surgeon. The short, thick handpiece may be improved for more convenient handling. Conclusion: Piezosurgery is a safe tool for selective bone cutting for opening of the IAC with preservation of facial nerve and hearing function in AN surgery. Piezosurgery has the potential to replace RD for this indication because of its safe and precise bone-cutting properties. [ABSTRACT FROM AUTHOR]

Abstract: The extended-reach horizontally-intersected well used to extract coalbed methane (CBM)can increase reservoir contact area, extend the influence scope of drainage-pressure drop and the district of CBM desorption. Furthermore, the extended-reach horizontally-intersected well can enhance unit well output and create favorable conditions for future workover. With the support of Major Projects of National Science and Technology, the research on key technologies of extended-reach horizontally-intersected well is done through theoretical analysis and experiment, the concrete research content includes selection of target formation and design of casing program, choice of survey instruments, research on the bottom hole assembly design and technique of steering wellpath, research on drilling fluid and extended-reach horizontally-intersected technology. As engineering examples of popularization and application of extended-reach horizontally-intersected well, a “U” shape well group located in Sihe mine field of Qinshui Basin and a “V” shape cluster well group located in Dafosi coal mine of Binchang mining area have been constructed successfully by using the integrated technologies. [Copyright &y& Elsevier]

The goal of this study was to investigate if the preparation of implantation site affects bone formation inside tissue engineering scaffolds. For this purpose, two different drilling techniques were used to create a hole in distal femurs of rats before the insertion of a bone scaffold: a manually driven wood drill bit and an electrically driven metal drill bit. The size and the position of the hole were identical for the two cases. The bone volume, bone mineral density, and callus formation were assessed noninvasively using micro-CT tomography at several time points after implantation. The formation of bone and soft tissue inside scaffold were evaluated by histology. The bone structure around the holes made by the two techniques was compared ex vivo. The long-term study of bone formation showed that when a wood drill bit was used, the bone formation is accelerated by 3 weeks compared to when a metal drill bit was used. The ex vivo studies suggest that this result is due to the drilling methods differentially affecting the structure of the bone surrounding the generated defects. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:767-772, 2011 [ABSTRACT FROM AUTHOR]

This paper presents measurements performed using an integrated centre hole drilling–deep hole drilling technique on two components:a butt-welded plate and a rail. The results were compared with those available from other measurement techniques and with finite element (FE) simulations of the residual stresses. It was found that incremental centre hole drilling and deep hole drilling worked well as complementary techniques. Subsurface deep hole drilling measurements performed in the welded plate at two locations produced very similar results and evidence of good repeatability. The present experimental results were found to be in reasonable agreement with other measurements and FE predictions of residual stresses. [ABSTRACT FROM AUTHOR]

Background: This study assessed the feasibility of anatomical coracoclavicular (CC) ligaments reconstruction, using three-dimensional (3D) measurement and virtual drilling., Methods: One-hundred-and-five 3D shoulder models were constructed using SuperImage software, based on computed tomography (CT) scan data. For each model the attachment sites and footprint dimensions of the CC ligaments were defined and adjusted according to constant anatomical ratios and individual measurement results. Different drilling techniques and 3D measurements were carried out separately on each model., Results: The collinear drilling technique with one bundle was used to breach the clavicle and/or coracoid process bone cortex in 38 of 105 models (36.2%); the percentage with two bundles was 90.5% (95/105). No cortical breach was observed using the non-collinear drilling technique., Conclusions: The non-collinear drilling technique provides the capability to prepare bony tunnels without any risk of cortical breach., (Copyright © 2014 John Wiley & Sons, Ltd.)