The skeletal-extension rates of the three main framework-building corals from the mid-late Holocene show distinct responses, either under the same environmental conditions, or within the same species under different conditions. Diploria labyrinthiformis , the only species found in both open and inshore-water environments, shows higher extension rates in the inshore waters of Castle Harbour (4.18 ± 0.56 to 5.55 ± 1.16 mm/year), compared to open water conditions at North Rock (2.53 ± 0.33 to 3.49 ± 0.68 mm/year). Some of these inshore extension rates also exceed those of the same contemporary species elsewhere in Bermuda and the Western Atlantic. Conversely, the extension rates of Pseudodiploria strigosa (2.71 ± 0.91 to 3.76 ± 0.68 mm/year), and the Orbicella annularis group (1.64 ± 0.32 to 2.75 ± 0.86 mm/year), are generally within the range of their contemporary counterparts in Bermuda but lower than those found in the Western Atlantic. Possible reasons for coral extension rate differences between locations turbidity, water circulation, depositional energy, sediment-clearing abilities of corals, and temperature as well as relationship of coral extension growth to reef accretion are discussed. • Skeletal extension rates of 14 selected Holocene fossil Bermuda corals were analysed • Holocene inshore framework corals have higher extension than those in open water • Holocene corals of the Orbicella annularis group show the lowest extension rates • Environmental energy and sediment suspension likely governed extension rate variation • Skeletal extension rate responses support the concept of “suppressed reef accretion”

Background: Fingertip injuries, particularly unstable distal phalanx fractures and open mallet-type extensor tendon injuries, impose a significant socioeconomic burden, especially on working-age adults in precarious employment. While internal fixation is often required to preserve alignment and function, the gold standard—Kirschner wire (K-wire) fixation under fluoroscopic guidance—is frequently inaccessible in emergency settings or for patients with limited financial resources. Methods: We present two patients presenting to the emergency department with unstable distal phalanx injuries. In the absence of intraoperative fluoroscopy and orthopedic power drills, stabilization was achieved using standard sterile hypodermic needles (18–21 gauge) as intramedullary or transarticular fixation devices. Results: Successful immediate stabilization was achieved in both cases. The needle fixation technique effectively reduced fracture displacement and, in the tendon injury case, restored the continuity of the extensor mechanism. At the final follow-up, all patients demonstrated maintained alignment and clinical fracture union. Functional outcomes were favorable, with patients regaining a pain-free range of motion at the distal interphalangeal joint and returning to daily manual labor without significant delay. Conclusion: Hypodermic needle osteosynthesis is a safe, accessible, and highly cost-effective technique for damage-control fixation of selected fingertip injuries.

Polycrystalline diamond (PCD) compacts are extensively applied in downhole drilling tools owing to their exceptional hardness and wear resistance. However, their tribological performance is strongly influenced by the thermal and chemical characteristics of drilling fluids. In this study, the coupled effects of temperature (25-125 °C) and oil-water ratio on the tribological behavior of PCD were systematically investigated. The results indicate that under relatively high oil-water ratios (50:50, 80:20, and 100:0), both the friction coefficient and wear rate increase monotonically with temperature, which is associated with intensified interfacial thermal stress and suppressed formation of protective carbon-based transfer films. In contrast, at low oil-water ratios (0:100 and 20:80), the friction coefficient exhibits a non-monotonic dependence on temperature, decreasing initially and then increasing with a transition near 100 °C. This behavior is attributed to temperature-activated surface passivation through C-OH bond formation in water-rich environments, followed by the deterioration of passivation due to water evaporation at elevated temperatures. These findings provide insight into temperature-dependent lubrication regime transitions and tribo-chemical evolution of PCD in complex drilling fluid environments.

Summary When drilling in high-strength, abrasive rock formations, rotary percussion drilling technology has garnered widespread attention for its efficient rock-breaking capabilities. However, existing investigations into the compatibility of polycrystalline diamond compact (PDC) cutters with rugged rock formations are still insufficient. Accordingly, based on rock dynamics theory, a numerical model for rock cutting by single-, dual-, and triple-cutter combinations composed of conventional cutters and special-shaped cutters, under dynamic-static load coupling, was established. The influence of laws of cutter type, rake angle, and cutter spacing with reference to depth of penetration and rock fragmentation output was assessed; the variation laws of rock-breaking effects under combinations of different cutter types and numbers were analyzed, and the multicutter rock-breaking mechanism under percussion drilling conditions was revealed. Research outcomes indicate that the axe cutter outperforms the planar cutter remarkably in terms of rock-breaking efficiency—its average penetration depth reaches 6.81 mm, which is 49.48% higher than that of the planar cutter (3.44 mm), and the corresponding cutting area (216.87 mm2) is also 54.0% larger than that of the planar cutter (140.81 mm2); among different cutter shape combinations, compared with the single-cutter setup, the dual-cutter structure outperforms in rock-breaking efficiency, and the combined planar-axe cutter arrangement attains the optimal effect; concerning the rake angle adjustment of the multicutter system, the optimal rake angle range for the front cutter is 15–20°, and the rear cutter achieves the best secondary fragmentation effect when its rake angle is 10–15°; in terms of the spacing setting in the multicutter system, the lateral spacing exerts a minor influence on the penetration depth, but the cutting area increases significantly with the increase in lateral spacing (with a total increment of 50.83 mm2); the effect of longitudinal spacing on penetration depth is deemed insignificant, but due to the reduced overlap of cutting zones, the cutting area gradually decreases as the longitudinal spacing increases (from 211 mm2 to 179 mm2). The findings provide valuable guidance for optimizing cutter geometry, designing cutter arrangements on drill bits, and enhancing drilling efficiency in deep formations.

The wear performance of 55SiMoVA bearing steel under extreme service conditions in oil and gas screw drilling tools is critical to the reliability and operational lifetime of thrust ball bearings. In service, these bearings experience severe friction between the balls and raceways, leading to accelerated wear and even catastrophic failure. Conventional surface modification techniques, such as carburizing, nitriding, shot peening, or surface coatings, provide limited improvements in surface properties and often fail to sustain high-load, high-temperature, and complex lubrication environments. Laser shock peening (LSP) has emerged as an effective surface engineering technique capable of inducing deep compressive residual stresses and forming a hardened surface layer, thereby enhancing both mechanical and tribological performance. In this study, 55SiMoVA steel specimens were treated using LSP with systematically varied process parameters, including impact energies of 4 J, 5 J, and 6 J, and impact numbers of one and two. The effects of these parameters on surface microstructure and mechanical properties were evaluated through surface roughness measurement, microhardness profiling, and X-ray diffraction-based residual stress analysis. To assess tribological behavior, reciprocating linear ball-on-block wear tests were conducted under lubrication with oil-based drilling fluid, simulating realistic service conditions. The results demonstrate that LSP markedly alters the surface and near-surface characteristics of 55SiMoVA steel. The maximum microhardness increase reached 17%, compressive residual stress exceeded 823 MPa, and the hardened layer extended to a depth of 1.3 mm, with a gradual stress gradient from surface to substrate. Single-impact treatments showed limited improvements in friction stability, whereas double-impact treatments significantly stabilized the coefficient of friction and enhanced wear resistance. Among all parameter combinations, the 5 J × 2-impact treatment exhibited the most favorable performance, reducing wear volume by approximately 15% compared to untreated specimens. Microscopic analysis of worn surfaces revealed that untreated samples displayed severe plowing and material spalling, while optimally treated samples exhibited relatively uniform and shallow wear tracks, indicating improved surface integrity. Overall, the study confirms that appropriate selection of LSP parameters can effectively enhance the surface hardness, residual compressive stress, and hardened layer depth of 55SiMoVA bearing steel, thereby significantly improving its wear resistance under lubricated conditions. These findings not only provide a practical surface engineering strategy for extending the operational lifetime of thrust ball bearings in screw drilling tools subjected to extreme and complex conditions, but also contribute to a broader understanding of LSP-induced surface modifications for high-strength alloy steels. The insights gained from this work offer valuable guidance for optimizing LSP processing parameters to achieve superior tribological performance and mechanical reliability in demanding industrial applications.

CNC machines are used in production industries for batch production. In CNC machining, a minor issue can cause production downtime, reducing productivity and profit for the Industry. In CNC machines, drilling machine maintenance is crucial because of the complexity of the drill tools. Drill tools have complex shapes and geometries, making tool wear prediction particularly challenging. Tool wear in CNC drilling severely hinders performance and affects the dimensional accuracy and surface finish obtained. This paper presents a machine-learning-based approach to drill wear detection using the Hilbert–Huang Transform for feature extraction from airborne Acoustic Emission (AE) signal and the CatBoost algorithm for classification. For controlled drilling operations, AE signals from four wear-condition samples representing Healthy Tool (HT), Low Wear (LW), Medium Wear (MW), and Severe Wear (SW) were recorded. Wear levels of 0.3mm,0.6mm, and 0.9mm for the drill bits of 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, and 3.8 mm diameters were created using Electrochemical Machining in the Lab. Using AE sensors, the signals were collected and converted into the required format with the support of signal conditioning and a data acquisition system. LabVIEW software was used to display the signal, and it was then decomposed using the Hilbert-Huang Transform (HHT) to obtain the required Intrinsic Mode Functions (IMFs). Features needed for classification, such as magnitude, entropy, and instantaneous frequency, were selected in the time-frequency domain. These features were used as input to a classifier (CatBoost), which was trained and evaluated using 10-fold cross-validation. HHT-CatBoost achieved 99.1% accuracy, indicating a promising sign for the proposed algorithm in real-time maintenance for small- to medium-sized datasets.

Industrial heritage movable assets, particularly the traditional machining tools used in manufacturing processes, are facing an increasing risk of disappearing due to the continuous advances in technology. Innovations in industry have progressively displaced many of these manual tools, making them obsolete or irrelevant in current manufacturing processes, remaining only for artisanal work. In this context, manual vertical drilling presses, which have played a crucial role in manufacturing for decades, are being displaced by more advanced machining tools, which incorporate technologies such as Computer Numerical Control (CNC). This work focuses on the development of a manual vertical drill press digital model, in order to virtually recreate its operation and structure. The software used to develop the model was SolidWorks (version 2024). This model aims not only to preserve a historically significant machine but also to serve as an educational resource, illustrating drilling operations before modern technologies emerged. Reconstructing them in 3D enhances the study and understanding of their mechanics and utility, ensuring access to technical knowledge and preserving their legacy in a digitalized world.

Rock geotechnical properties can be reflected in drill signals while drill rod penetrates through rocks. The rate of penetration, rotary speed, torque, load, sound, vibration, etc., are different for various rock types, since they are influenced by rock properties. Therefore, a close analysis and derivations of these drill signals can provide valuable insights into rock geotechnical properties. The drill returned signals from the mechanical sensors; for example, torque and load are commonly interpreted to characterize the rock properties. There are still limitations to such sensors and interpretation methodologies that can confidently characterize rock properties. In this research, mechanical sensors were compared and complemented with seismic sensors, for example, accelerometers and geophones, to characterize rocks and interfaces. This paper presents experimental results conducted with synthetic rock samples using mechanical and seismic sensors with a field scale drilling machine. The results show that seismic sensors can identify voids or weak (fractured) interfaces clearly compared to mechanical sensors. Smaller gaps have smaller span of low frequency and vice versa. The sensors attached to the drill head were less sensitive than the sensors attached to the sample. Drill signals showed the capacity to effectively identify material interfaces and weak fractures up to 4 mm thick, with geophones providing clearer data than accelerometers. Neither sensor distinguished fractured zones from voids. Sensors mounted directly on the sample were more sensitive than those attached to the drill head, likely due to vibration-induced signal attenuation at the drill head.

An approach for quantifying the three-dimensional joint roughness coefficient of rock joints during rotary drilling

Abstract To address technical bottlenecks such as insufficient power, low rock-breaking efficiency, poor directional control accuracy, and inadequate experimental testing capabilities in the horizontal directional crossing of hard rock formations, this study investigates key technologies for high-efficiency rock-breaking equipment associated with high-torque drilling tools. The research achieves three significant technological breakthroughs: integrated structural design, the combination of measurement while drilling with guidance control, and the optimization of experimental testing systems. Consequently, the Type 340 high-torque drilling tool, the Type 172 integrated measurement and guidance system, and a complete machine experimental platform rated at 30 KN·m have been developed. Utilizing the NSGA-II algorithm for motor parameter optimization, this study integrates composite PDC bearings with high-pressure jet-assisted rock-breaking technology. An innovative nine-axis attitude measurement and unscented Kalman filter fusion algorithm is proposed, alongside forward testing and a combined loading method for the reducer. Experimental results and field applications demonstrate that the maximum output torque of the drill reaches 40 KN·m, making it suitable for hard rock formations exceeding 200 MPa, with a 50% increase in rock-breaking efficiency. The measurement delay is less than 5 seconds, and the guidance control accuracy is ± 0.1°. Furthermore, the experimental testing accuracy achieves ± 1.5%, with a dynamic testing range extending to 30 KN·m. This technological system effectively addresses core challenges in hard rock crossing and provides reliable technical support for long-distance, large-diameter hard rock crossing projects.

Abstract The power head is one of the core components of a reverse circulation drill, providing the necessary torque and rotation for the drill pipe and tools. The thermal network method is applied in this paper to establish steady-state thermal equilibrium equations for key positions of the power head, developing computational models for heat sources, thermal resistances, and convective heat transfer coefficients. The steady-state temperature distribution of the power head is obtained by solving nodal temperatures from the thermal equilibrium equations, with experimental validation performed on selected node temperatures. It is shown that gear tooth surfaces and bearing rings exhibit higher temperatures than other positions, with the driving gear’s tooth surface reaching peak temperatures. The steady-state thermal analysis is conducted in accordance with fundamental thermodynamic laws, and theoretical temperature values are found to be within acceptable error margins. The findings of this study lay a theoretical foundation for the thermo-mechanical coupling analysis of components within the reverse circulation drill power head.

Summary Drill cuttings are small rock fragments generated by the action of the drill bit during rotary drilling operations. The rock type (lithology) identification and quantification from drill cuttings provides critical information for underground characterization. The common practice of mudlogging—to identify the lithology from cuttings—is time-consuming and subjective. The previous efforts in automating lithology characterization from drill cuttings focused on analyzing cuttings optical images with convolutional neural networks (CNNs). The success is limited as many samples are not visually distinct. HyLogger-3 is an automated drill cuttings and core profiling system, providing both optical images and hyperspectral data of samples. In this study, a multimodal machine learning (ML) approach is developed to automate lithology prediction from cuttings. A CNN classification model is first trained for extracting the image features from 2D optical images of cutting samples in red, green, and blue (RGB) channels. Mineral information is derived from HyLogger hyperspectral data by comparing measured reflectance spectra with pure mineral reference spectra and applying spectral unmixing methods to quantify the abundance of individual minerals within each sample. The extracted image features are in the form of a 1D list of float numbers and can be concatenated with another 1D list of mineral information to further build a multimodal ML model. An XGBoost-based regression approach is used in the multimodal ML modeling, where the percentage of different lithology types (mudlogs) in cuttings samples can be directly used to train the ML model, and the trained model can produce mudlogs on HyLogger-3 data from randomly selected blind samples. The blind test results indicate that the multimodal ML model delivers a practical solution for automated mudlog generation in both pure and mixed lithology samples, matching interpretations of geologists with discrepancies of 10.16% in root mean square error (RMSE) and 4.84% in mean absolute error (MAE).

Abstract A clustered high-torque power drilling tool design is proposed to overcome technical challenges in large-diameter, long-distance horizontal directional crossing projects, such as insufficient torque, high risk of stuck pipe, and poor formation adaptability. The design integrates multiple screw-type drills into a cluster, utilizes a hydraulic torque converter for coordinated power transmission and overload protection, and enhances impact resistance by replacing traditional series bearings with cross cylindrical roller bearings. Motor parameter selection is optimized using MATLAB algorithms, while ANSYS and ABAQUS software analyze key component strength and modal optimization of the drill assembly. Three field engineering validations confirm that the optimized drill achieves torque output exceeding 50 kN·m, overload capacity of 400 t, and a service life exceeding 300 hours. Compared to traditional drills, the construction efficiency improves by over 1.5 times, leading to a 60% reduction in costs. The design effectively meets the requirements of crossing medium-hard to hard rock formations (uniaxial compressive strength 20 – 100 MPa), providing essential equipment support for non-excavation directional crossing projects.

This paper develops an approach to modelling, analysing, and controlling coupled torsional-axial vibrations and mud flow dynamics in rotary drilling systems. Our novel PDE-ODE-ODE formulation captures the complex interactions between drillstring dynamics and Managed Pressure Drilling (MPD), with established well-posedness and controlled stability properties. The control strategy combines backstepping techniques with Lyapunov theory to guarantee stability, while the d'Alembert transformation enables tractable displacement analysis through conversion to a neutral system. Numerical validation demonstrates the strategy's effectiveness in vibration mitigation and operational safety enhancement for drilling systems.

High Voltage Cable Channel Work (SKTT) 150 kV or Underground High Voltage Cable works can be carried out using the Horizontal Directional Drilling (HDD) machine, in accordance with the State Electricity Company Standard (SPLN) T4.003:2023, and is commonly applied in urban areas with high traffic density. This article analyzes the failure of the High Density Polyethylene (HDPE) pipe pulling process in the 150 kV SKTT work at the MRT Jakarta Phase 2A Project, CP 205. The failure occurred due to a time delay of approximately 4 hours between the borehole cleaning process and the pulling operation. This condition resulted in the failure of pulling HDPE PN10 pipes with diameters of 6 inches and 4 inches. Corrective actions were conducted by reaming the original borehole using the same parameters. The pulling operation was then performed immediately after the cleaning process was completed. The evaluation results indicate that eliminating any time delay between the cleaning and pulling processes can prevent borehole collapse and ensure the successful installation of HDPE pipes in 150 kV SKTT works.

Problems in the transmission box of the Drilling Machine 438-02-814-0925 type (0.75 HP, 230/400V, 1425 rpm, produced in 1988) are the degradation of mechanical components for the pulley, V-belt, and rolling bearing. The purpose of maintenance and repair planning is to obtain maintenance costs, maintenance schedules in the period 2026, and the ratio of maintenance costs to profits. The maintenance and repair planning method includes collecting previous maintenance data; application of the inspection-replace-repair-overhaul (IRRO) method; evaluation of the working conditions of components, especially on the pulley, V-belt, spindle pulley (driven pulley), and rolling bearing; prediction of component service life; prediction of repairman costs; prediction of supporting equipment that will be used in maintenance; prediction of spare part replacement time or reinstallation of components after repair; estimation of maintenance and repair costs in 2026; and calculation of the ratio of maintenance costs to profits. The results of maintenance and repair planning obtained maintenance costs in 2026 amounting to Rp 4,627,000 with an estimated Drilling Machine rental rate of Rp 75,000/hour which has the opportunity to be rented for 400 hours/year, and a maintenance cost to profit ratio of 15.42% which implies that the Drilling Machine still has the opportunity to generate profits and is suitable for use in the coming years.

Introduction To reduce severe drill string vibration and improve drilling efficiency in deep drilling, which are often accompanied by significant energy loss. Method The contra- rotation of the inner and outer drill bits was facilitated by planetary gear transmission, and the anti-torque fluctuation was reduced by the torque balance principle, thereby suppressing vibration. In this paper, the design of the gear, bearing, and seal structure of the contra-rotating drilling tool was completed; single rotation and contra-rotating drilling tools were prepared alongside artificial rock samples; a drilling test rig was constructed; and vibration signals of the drilling tools were collected at different rotation speeds. Result Time-domain and frequency-domain analyses revealed that the vibration acceleration amplitude of the contra-rotating drilling tool in the X, Y, and Z directions is significantly lower than that of the single rotation drilling tool. Furthermore, with increasing rotation speed, the vibration amplitude of the contra-rotating drilling tool remains stable or even decreases, whereas the vibration of the single rotation drilling tool increases significantly. Discussion A mechanistic analysis revealed that the contra-rotating drill bit requires less driving force to break rock, produces more shear failure zones, breaks rock more easily, and generates less vibration. This study provides an effective active control method for reducing drilling vibration and has good prospects for application in the field of engineering.

The advent of designing flexural systems was to provide accurate micro and nano displacement between the assembly members of the mechanism. Applications that used these mechanisms included linear compressors, optomechanical devices, Stirling engines, cryocoolers, microcheck valves, Flexure-based Electromagnetic Linear actuators, and so on. This paper focuses on the machine-tool fabrication of a novel flexural mechanism encased within the spindle head of the microdrilling head. The mechanism cushioned the micro drill and protected it from permanent damage when encountering undeclared resistance in the material matrix. Furthermore, this paper focuses solely on building a 3-axis drilling machine tool in a Product Lifecycle Management environment. The study follows a systematized approach for validating the machine tool design, starting with the hierarchical assembly of components using various kinematic chains. The next phase involves assigning the necessary motions to these components. The final stage utilizes a virtual controller and post-processor to simulate and control machine tool movements. Validation is then performed on the simulated workpiece to ensure design accuracy and functionality. The key findings of the studies indicate that the designed mechanism can move in and out and can also puncture micro-holes in metal. This is the mechanism’s capability, which is the novelty.

Abstract This work details a methodology for the design of small-scale wave energy converter (WEC) prototypes, consolidating design knowledge and techniques while contributing to the production of higher-quality, fundamental WEC research. The methodology is applied in the design, build, and deployment of two WEC architectures: heaving point absorbers (PAs) and oscillating surge WECs (OSWECs). Relevant design considerations are described in depth, including testing facility, fluid regime, model physics, mechanical design, and electrical design. The design process is validated through experimental results, and recommendations are made for improvements on small-scale WEC systems. Minimizing friction at the small-scale is a known challenge, but the implemented rack and pinion powertrains satisfied requirements. Additionally, electrical current measurement resolution becomes a limiting factor at the small-scale, prohibiting effective controls and electrical power generation. Almost all components were purchased off-the-shelf or machined using standard tools (bandsaw, drill press, hand tools), with a few CNC-milled, waterjet, and lasercut components. A table of generalized, universal requirements for small-scale WEC development is provided. This methodology serves as a guide for small-scale WEC design and testing, improving design techniques and datasets generated from experimentation.

The study aimed to examine a technology for machining holes with an automatic drilling machine during the assembly of a large hybrid structure (polymer composite material + metal) with the use of modular equipment. In order to analyze the process of hole machining in large structures during their assembly, a wing box model measuring 17,765x3050x438 mm was assembled to simulate a civil aircraft wing box – a test wing box. The used modular equipment provides a geometric position accuracy of 0.5 mm in hole machining. In order to machine holes using an automatic drilling machine, a hole machining map was created. This map details key hole parameters such as hole diameter, hole accuracy, hole center coordinates, and hole axis direction, as well as material layers. To align the automatic drilling machine with a large structure, the map of holes to be machined should be divided into areas (in the case of long parts, into subareas). It was found that the technology for machining holes with numerically controlled automatic drilling machines using a combination tool allows holes to be machined in large hybrid structures to their final diameter in one or two passes, ensuring a geometric position accuracy of 0.5 mm. The study of hole machining in large structures revealed that in order to achieve a geometric position accuracy of 0.5 mm in automatic hole machining, long parts should be divided into subsections of no longer than 1 m. The overall length of the reference zone for the automatic drilling machine was determined. The obtained results can be used to optimize hole machining in large structures in aviation, shipbuilding, and other industries.