Drilling Frequency Research Articles

ALARMING AND WARNING MODEL FOR IMPROVING THE EFFECTIVENESS OF SEQUENTIAL EVACUATION FROM HIGH-RISE BUILDINGS

The article presents the results of research conducted during trial evacuations from high-risebuildings. Based on the surveys, areas were identified where the evacuation process requiressupport and an alarm model was proposed to shorten the total evacuation time.Two series of trial evacuations from buildings were carried out, involving 1,333 respondents.The survey was carried out in 28- and 24-storey office buildings, where companies with differentbusiness profiles, e.g. consulting, accounting, media and others, were based. The questionnaireincluded 16 questions and was distributed in printed form to each participant of the evacuationattempt, and the completed questionnaire was collected shortly after returning to the office. Thequestions posed in the survey concerned, among others, the comprehensibility of the alarmmessage, concerns and other feelings during evacuation, the influence of other people at thestart of evacuation, knowledge of people who might need help, knowledge of people responsiblefor evacuation, estimated time devoted to preparation for evacuation, description of additionalactivities performed, preferences for choosing the evacuation method between stairs and elevator,general opinion on the need to carry out exercises, demographic data, etc.Interviewees confirmed that those taking part in the exercise may have doubts about the need tostart an evacuation. Intensifying the frequency of evacuation drills increases employees’ reluctanceto participate in them. It was confirmed that the alerting process is a phenomenon of socialinteraction, and to ensure correct alerting it is necessary to use the direct influence of peopleresponsible for the evacuation on other employees to communicate messages in as much detail aspossible. People who were not familiar with the building were characterized by a higher level ofnegative feelings about the evacuation process and a longer reaction time to the alarm.The use of a voice alarm system in a building guarantees high intelligibility of messages. A modelof evacuation messages was proposed to reduce doubts as to the need of starting an evacuation, dedicated to individual areas of the building, enabling shortening of the total evacuation time. Themodel is clear in its description of the threat and takes into account various possibilities of locatingpeople in relation to this threat.

Emergency preparedness in the central sterile supply department: a multicenter cross-sectional survey

ObjectiveTo investigate the current situation of emergency preparation and emergency drill in the CSSD, and analyze its influence on the nurses’ emergency attitude and ability.MethodsThis study employed a multicenter stratified sampling method, conducted from January to June 2023 using the online survey, participants completed the general data, emergency preparedness and drill questionnaire, public health emergency response questionnaire and emergency capacity scale. An independent samples t test or Kruskal-Wallis test was used to analyse differences in nurses’ emergency capacity and attitudes.ResultsThe data from 15 provinces 55 hospitals in China. Overall, 77.58% of participants’ institutions set up emergency management teams, 85.45% have an emergency plan and revise it regularly. 92.12% store emergency supplies. All survey staff participated in the emergency drill, which predominantly consisted of individual drills (51.52%), with 90.30% being real combat drills, 49.09% of participants engaging in drills every quarter, and 91.52% of the drill’s participants exceeding 50%. The respondents’ emergency attitude score was (29.346 ± 6.029), their emergency ability score was (63.594 ± 10.413), and those with rescue experience showed a more positive attitude (Z = -2.316, P = 0.021). Different titles, education levels, rescue experience and the frequency of emergency drill affected the emergency rescue ability of the respondents (P < 0.05).ConclusionsMost medical institutions establish emergency management systems and plans, yet the content lacks geographical specificity.The duration and participation of emergency drills are high, but the effectiveness of the drills needs to be further improved, and the response capacity and attitudes of CSSD nurses are low. It is recommended that agencies develop comprehensive and targeted contingency plans to strengthen the inspection and evaluation of team strength, equipment and safeguards against the contingency plans, so as to ensure that the measures mandated by the contingency plans can be implemented promptly after the emergency response is initiated.

An optimization model for monthly time-step drilling schedule under planned field production

The field production profile over the yearly horizon is planned for a balance between economy, security, and sustainability of energy. An optimal drilling schedule is required to achieve the planned production profile with minimized drilling frequency and summation. In this study, we treat each possible production process of each well as a dependent time series and the basic unit. Then we ensemble all of them into a tensor. Based on formulated tensor calculation and Lasso regularization, a linear mathematical optimization model for well drilling schedule was developed. The model is aimed at minimizing production profile error while optimizing drilling frequency and summation. Although the model proposed in this work requires more memory consumption to be solved using a computer, it is assured as a linear model and could be numerically globally solved in a stable and efficient way using gradient descent, avoiding complex nonlinear programming problems. Main input data and parameters involved in the model are analyzed in detail to understand the effects of different production parameters on the drilling schedule and production profile. The proposed model in this work can evaluate the manual drilling schedule and automatically generate an optimized drilling schedule for the gas field, significantly reducing development plan formulation time.

Predatory drilling on molluscan assemblages along the Patagonian shelf (southern Argentina)

Abstract Both present-day and fossil molluscan assemblages offer an opportunity for a better understanding of the structure and organization of both modern and past benthic communities. In this framework, drill holes are used widely to explore predator–prey interactions. This research focuses on predation marks, especially drill holes, recorded on modern molluscan assemblages in a Patagonian sector of the Argentinean continental shelf. Shelled molluscs (n = 2179) were recovered from 27 to 135 m depths covering a long latitudinal extent (between 39° and 54°S). For each station, taxonomic position, ecological composition and relative abundance of taxa were determined, and then drilling frequency (DF) was calculated to infer drilling intensity. The collected molluscs belong to 37 families, with Veneridae being the most abundant in terms of the number of specimens (n = 419). Specimens with drill holes (n = 226) belong to 21 families (with at least 33 different species). Most of them are suspension feeders (85.8%) and the remaining percentage comprised other trophic types. Naticids and muricids, as main potential predators, together account for 19.6% of the gastropods present in the molluscan assemblages. DF across all the stations was moderate (9.9%) but varied between low (0–2.4%) and high (28.9%). These results do not show a trend linked to latitude or depth, and the great variability of DF between stations suggests that other local ecological or environmental conditions would influence drilling predation at a small spatio-scale.

Enhancing the benefit of slide steering drilling systems in horizontal wells of unconventional reservoirs

The slide steering drilling system consisting of a bent positive displacement motor (PDM) and measurement while drilling (MWD) system is widely used to continuously implement all wellpath control operations by alternately applying the slide and compound drilling modes. Due to the large friction force on the drilling string during slide drilling in the horizontal section, there is a significant adverse impact on both the drilling speed and horizontal extension ability. To efficiently and economically drill long horizontal sections, it is essential to increase the compound drilling proportion and decrease the alternative times of the two drilling modes. According to the features of wavy or tortuous horizontal sections and wellpath calculation models, a prediction and control method for the compound drilling proportion of horizontal sections is first established, and subsequently, its influencing factors and laws are analyzed and verified using an example. Theoretical research and drilling practice have shown that the compound drilling proportion of the horizontal section depends on the build-up rate of slide drilling and the inclination and azimuth change rates of compound drilling and is independent of the target area parameters and wellpath fluctuation ratio. In order to increase the compound drilling proportion and reduce the slide drilling frequency in the horizontal section, it is necessary to increase the build-up rate of slide drilling properly and reduce the inclination and azimuth change rates of compound drilling to the greatest extent. This paper is helpful to enhance the benefit of slide steering drilling systems in horizontal wells of unconventional reservoirs.

Hospital Disaster Preparedness: A Comprehensive Evaluation Using the Hospital Safety Index

Mass-casualty incidents and disaster scenarios pose significant challenges for medical facilities, necessitating robust preparedness measures. This study aimed to evaluate the preparedness of a specific medical facility in Poland, using the hospital safety index (HSI). A comprehensive analysis of structural, functional, and organizational factors was conducted, assessing facility infrastructure, technical facilities, safety standards, work organization, cooperation with external facilities, human resource management, crisis planning, and communication strategies. The facility exhibited strengths in infrastructural requirements and inter-facility cooperation. Areas of improvement included adherence to safety procedures, crisis communication, and the frequency of evacuation drills. Furthermore, recommendations were provided for enhancing nurse reserves, adopting lean management, promoting a safety culture, and refining business continuity plans. The findings should be interpreted with caution, due to the single-facility focus, potential HSI protocol subjectivity, and the possible Hawthorne effect. This study underscores the importance of continuous research and improvement in crisis management strategies and disaster-victim care, emphasizing the pivotal role of the HSI as an evaluative tool.

THE ROLE OF DRILLING PREDATION IN ISOLATED, NUTRIENT-POOR ECOSYSTEMS: FIRST INSIGHTS FROM RAPA NUI, POLYNESIA

Abstract As a biotic interaction, drilling predation is affected by the evolutionary histories of the predator and prey, as well as the environment. A unique location with distinctive evolutionary histories and environmental conditions is the remote island of Rapa Nui. For mollusks, an evolutionary history in relative isolation has led to high rates of endemism (35–40%), in an area that has some of the most nutrient-poor waters of the global ocean. Here, we use death assemblages collected in Rapa Nui to answer two main questions: (1) How does a pervasive interaction like drilling predation play out in an isolated, oligotrophic marine system? and (2) What role do the environment (exposed vs. sheltered sites) and species traits (feeding, mobility, life habit) play in ‘protecting' the prey? We predicted that predation would be low relative to other tropical and subtropical islands given the oligotrophic conditions and found that the average drilling frequency (DF) was 5.67% (n = 6122). We observed no significant differences in DF between feeding guilds, mobility types, or life habits. Sheltered sites dominated by the infaunal bivalve Ctena bella had higher predation. In terms of passive defenses for C. bella, larger body size was not an effective defense against drilling predators. We show that drilling predation in Rapa Nui is lower than in high-latitude regions, and it is dependent on how sheltered or exposed sites are. Historically and currently, Rapa Nui has been subject to multiple anthropogenic stressors, including over-extraction and tourism, making efforts to understand its endemic species and their interactions fundamental.

Environmental correlates of molluscan predator–prey body size in the northern Gulf of Mexico

AbstractThe Mississippi River watershed drains 40% of the continental United States, and the tremendous primary productivity in the adjacent north-central Gulf of Mexico has created one of the most extensive dead zones on Earth. In contrast, smaller watersheds deliver fewer nutrients to the northeastern gulf, and consequently, productivity is limited and hypoxia is uncommon. How has variation in primary productivity, oxygen availability, and sea-surface temperature affected coastal food webs? Here, we investigate environmental controls on the size of molluscan predators and prey in the northern Gulf of Mexico using Holocene death assemblages. Linear mixed models indicate that bivalve size and the frequency of drilling predation are affected by dissolved oxygen concentrations; drilling frequency declines with declining oxygen, whereas bivalve size increases. In contrast, sea-surface temperature is positively associated with the size of molluscan predators and prey. Net primary productivity contributes relatively little to predator or prey size, and predator-to-prey size ratios do not vary consistently with environmental conditions across the northern gulf. Larger bivalves in areas of oxygen limitation may be due to decreased predation pressure and, consequently, greater prey longevity. The larger size of bivalves and predatory gastropods in warmer waters may reflect enhanced growth under these conditions, provided dissolved oxygen concentrations exceed a minimum threshold. Holocene death assemblages can be used to test long-standing hypotheses regarding environmental controls on predator−prey body-size distributions through geologic time and provide baselines for assessing the ongoing effects of anthropogenic eutrophication and warming on coastal food webs.

Elements that associate with participants’ psychological discomfort during simplified fire drills

Fire drills may reinforce the survival skills of participants on the one hand, and on the other hand, they might bring a certain amount of psychological discomfort. To identify elements associated with the psychological discomfort, a designed questionnaire was distributed to postgraduate students who had experienced fire drills in Islington (London) and 1640 valid responses were obtained. With the help of regression analysis, this research found that participants' awareness of precaution, individual initiative of participation, the personal judgement of simplified fire drills (SFDs), participation of SFDs, evaluation of SFDs' function in practical applications, and satisfaction with SFDs' performance are positively associated with participants' psychological discomfort, while the procedural arrangement of SFDs, time interval of joining in the last SFD, and the frequency of simplified fire drills experienced are negatively associated with participants' psychological discomfort. Moreover, personal awareness of precaution, individual initiative of participation, individual satisfaction with SFDs' performance, the time interval of joining in the last SFD, procedural arrangement of SFDs, and the frequency of simplified fire drills experienced could explain 30.02% of the variance in participants' psychological discomfort.

Concordant Spatial Gradients in Predation Intensity and Productivity Archived in Surficial Mollusk Shell Accumulations in Seagrass Meadows Along the Gulf Coast of Florida

Seagrass meadows are highly structured habitats of great socioeconomic value but are declining globally due to human impacts. The northern Gulf Coast of Florida contains one of the largest relatively unaltered seagrass habitats (~3,000 km2), making it a model system for acquiring baselines to better manage and monitor seagrass meadows. This project investigated spatial gradients in ecological and taphonomic attributes of surficial seagrass-associated benthic mollusk death assemblages. An updated analysis of water parameters (based on project COAST data) indicated that total dissolved phosphorous (TDP) and chlorophyll-a (CHL-a) concentrations increased steadily northward. To analyze the historical ecology of local seagrass meadows, mollusk assemblages were bulk sampled at 12 stations across multiple estuaries along the gradient. Radiocarbon dating of valves (n = 90) from several estuaries indicated that the assemblages represented a multi-millennial accumulation with a median shell age of 1760 AD. Focusing on two abundant bivalves found within all estuaries, Transennella spp and Crassostrea virginica, the study evaluated spatial trends in body size, traces of predation, and post-mortem shell alterations. The results, primarily focused on Transennella spp., indicated that ecological and taphonomic characteristics varied notably, both among and within estuaries. Relative abundance, body size, and taphonomic attributes did not appear to correlate significantly with productivity or drilling frequency. However, drilling frequency correlated significantly with TDP and CHL-a, suggesting that predator-prey interactions may co-vary tightly with productivity. These results suggest that spatial gradients in predation can be archived by drilling frequencies in death assemblages. Moreover, the consistency between the long-term record of predation and modern gradient conditions suggests that long-term spatial dynamics of predator-prey interactions may be hydrologically controlled.

Factors on vibrational harm during hammer drilling – Influences of lateral force, feed force, hammer drill and drill bit type

When using hammer drills, the user is exposed to vibrations which can cause damage to the body. Those vibrations can be affected by external factors such as feed forces, which can increase the degree of damage to the user. However, currently there is a lack of knowledge as to whether the lateral forces applied by the user also have an influence on the technical system and whether these influences depend on the system. For this reason, a study with 1152 test runs was carried out on a test rig to investigate the relationship between the feed force and the lateral force as a function of the hammer drill setup on the vibrations at the hammer drill housing and main handle. The experiment showed that the feed (p = < .001, up to r = 0.57) and lateral (p = < .001, up to r = 0.77) forces had an influence on the vibrations of the hammer drill. However, these depended strongly on the technical system and hence cannot be generalized. Furthermore, it was proven that the impact frequency of the hammer drill was reduced by increasing both the feed force (p = < .001, r = 0.55) and the lateral force (p = < .001, r = 0.23). The findings can not only be used by engineers and scientists to further develop vibration standards, but also to design more ergonomic hammer drills. Hence, the vibration decoupling of hammer drills should be redesigned so that lateral forces do not lead to an increase in vibrations that are harmful to the user.

Theoretical study on fatigue damage of sonic standing wave resonant drill-string

To achieve high-speed and undisturbed core drilling, the standing wave vibration of the drill string in a sonic drill is excited by a high-frequency inertial vibrator; the resulting high alternating stress cycle in the drill string can easily cause fatigue damage. In order to minimize the fatigue failure of drill-string at the stage of its design, it is necessary to assess the fatigue damage caused by alternating stress to guide engineering practice. In this paper, based on one-dimensional wave theory, we analyse the standing wave vibration in a drill-string excited by a sonic vibrator, and theoretically prove that the dynamic resonant stress of a drill-string is the key factor influencing the fatigue damage. By using the Palmgren–Miner fatigue damage rule, we establish a theoretical formula for the cumulative fatigue damage of a variable-length standing wave vibration drill string and reveal the fatigue damage mechanism of the variable-length resonant drill string. Furthermore, the effects of sonic drill systems and process parameters on the damage are quantified. It was found that by an appropriate choice of a drill-pipe length, the fatigue damage can be reduced whilst the axial stress concentration factor (aSCF) kσ on threaded connections can significantly increase it. At the fundamental frequency of the resonant sonic drilling, the maximum fatigue damage point, xf, is located approximately la/2 above the drill bit, not exceeding the theoretical sonic standing wave starting length, la, and unrelated to the hole depth. This study promotes the theoretical understanding and exploration of variable-length standing wave oscillators.

Robot-Assisted Versus Conventional Freehand Fluoroscopy-Guided Percutaneous Screw Fixation in Femoral Neck Fractures: A Systematic Review and Meta-analysis.

Robotic-assisted navigation for percutaneous femoral neck fracture fixation is a new technology that has shown enhanced intraoperative and postoperative outcomes compared to the conventional freehand fluoroscopy-guided technique. The authors aim to compare robot-assisted femoral neck fracture fixation to conventional freehand fluoroscopy-guided repair. Electronic databases were searched, identifying all observational studies comparing outcomes of both groups. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis were conducted. The primary outcomes included operative duration (minutes), intraoperative bleeding (mL), fluoroscopy exposure, and frequency of intraoperative drilling. The secondary outcomes included Harris scores, healing rate and time, screw accuracy, and postoperative complications. Seven observational studies were identified, enrolling 506 patients. There was a significant difference between the robot-assisted and conventional groups in terms of intraoperative blood loss (mean difference (MD) = -18.83, p ≤ 0.05), fluoroscopy exposure (MD = -1.81, p ≤ 0.05), and intraoperative drilling frequency (MD = -7.35, p < 0.05). There was no significant difference in operative duration between the groups (MD = -0.21, p = 0.66). Most secondary outcomes were improved in the robot-assisted group. Overall, robot-assisted fixation was superior in terms of safety and efficacy.

Scale dependence of drilling predation in the Holocene of the northern Adriatic Sea across benthic habitats and nutrient regimes

AbstractPredation has strongly shaped past and modern marine ecosystems, but the scale dependency of patterns in drilling predation, the most widely used proxy for predator–prey interactions in the fossil record, is a matter of debate. To assess the effects of spatial and taxonomic scale on temporal trends in the drilling frequencies (DFs), we analyzed Holocene molluscan assemblages of different benthic habitats and nutrient regimes from the northern Adriatic shelf in a sequence-stratigraphic context. Although it has been postulated that low predation pressures facilitated the development of high-biomass epifaunal communities in the eastern, relatively oligotrophic portion of the northern Adriatic shelf, DFs reaching up to 30%–40% in the studied assemblage show that drilling predation levels are comparable to those typical of late Cenozoic ecosystems. DFs tend to increase from the transgressive systems tract (TST) into the highstand systems tract (HST) at the local scale, reflecting an increase in water depth by 20–40 m and a shift from infralittoral to circalittoral habitats over the past 10,000 years. As transgressive deposits are thicker at shallower locations and highstand deposits are thicker at deeper locations, a regional increase in DFs from TST to HST is evident only when these differences are accounted for. The increase in DF toward the HST can be recognized at the level of total assemblages, classes, and few abundant and widespread families, but it disappears at the level of genera and species because of their specific environmental requirements, leading to uneven or patchy distribution in space and time.

Robot-assisted versus conventional percutaneous sacroiliac screw fixation for posterior pelvic ring injuries: a systematic review and meta-analysis.

Robot-assisted pelvic screw fixation is a new technology with promising benefits on intraoperative outcomes for patients with posterior pelvic ring injuries. We aim to compare robot-assisted pelvic screw fixation to the traditional fluoroscopy-assisted technique with regards to intraoperative and postoperative outcomes. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used along with a search of electronic information to identify all studies comparing the outcomes of robot-assisted versus conventional screw fixation in patients with posterior pelvic ring injuries. Primary outcomes included operative duration(minutes), intraoperative bleeding(mL), fluoroscopy exposure and intraoperative drillingfrequency. Secondary outcome measures included Majeed score, healing time (minutes) and rate (%), postoperative complications, screw positioning, incision length (cm) and guide wire insertion times (minutes). The random effects model was used for analysis. Four observational studies including a total of 294 patients were identified. There was a significant difference between robot-assisted and conventional groups in terms of operative duration (MD = -24.66, p < 0.05), intraoperative bleeding (MD = -10.37, P < 0.05), fluoroscopy exposure (MD = -2.15, P < 0.05) and intraoperative drilling frequency (MD = -2.42, P = < 0.05). For secondary outcomes, no significant difference was seen in Majeed score, healing time and rate and postoperative complications. The robot-assisted group had better screw positioning, smaller incision length, and shorter anaesthesia and guide wire insertion times. Robot-assisted fixation has superior intraoperative outcomes compared to conventional fixation. Further studies are needed to look at postoperative outcomes as there is no significant difference in postoperative prognosis between the techniques.

Middle Miocene serial killers: Drilled gastropods from the south-western margin of the Central Paratethys, Croatia

This paper focuses on traces of drilling predation in the middle Miocene gastropod assemblage of the Zaprešić Brijeg locality, Croatia, which provides further insight into the palaeoecology of the south-western margin of the Pannonian Basin System during the Badenian. The analyzed gastropod shells were collected in the first half of the 20th century, and are housed in the Croatian Natural History Museum (CNHM) in Zagreb. The CNHM Zaprešić Brijeg collections contain 11063 gastropod shells, of which 1024 have been identified as drilled (9.3% of the sample), with 633 successfully drilled, 113 unsuccessfully drilled, and 278 multiply drilled shells. The most represented families are Potamididae, Nassariidae, Clavatulidae, Turritellidae, Cerithiidae, Muricidae and Naticidae. The gastropod families Naticidae and Muricidae are recognized as the probable predators based on the shape of the drill holes. Middle Miocene (Badenian) gastropods drilling frequency at Zaprešić Brijeg is 5.72%, which is lower than the recorded Badenian gastropods drilling frequency in the Central Paratethys, while the overall gastropod prey effectiveness from the studied locality (15.15%) is higher than the average of the neighbouring Badenian localities in the Central Paratethys. Among the most represented gastropods at this locality, the highest drilling frequency occurs in the infaunal suspension feeders Turritellidae (14.45%), which mostly show traces of the naticid drilling.

Predator–prey interactions among Pliocene molluscs from the Tjörnes Peninsula, Iceland; across the trans‐Arctic invasion

The fossil record provides a long-term perspective to better understand the impacts of species invasions in their environmental contexts. Temporal analyses of predator–prey interactions from the Tjörnes deposits, Iceland, track naticid gastropod drilling predation across the trans-Arctic invasion (TAI: ~3.5 Ma). These deposits represent three zones subdivided into 25 marine fossil-bearing beds that correspond with the stages of invasion: Tapes (1–5) and Mactra (6–12) zones are pre-invasion, whereas the Serripes zone (13–25) represents the invasion. Bivalve and naticid gastropod specimens were analysed from the Bárðarson (1925) samples at the Icelandic Institute of Natural History, which consisted of pre-invasion and invasion samples; we also bulk-sampled the Serripes zone. Height and length of specimens were measured to assess size changes, and the occurrence of complete and incomplete drill holes and drill hole diameter were recorded for whole bivalves and naticids. Drilling frequency (DF) and prey effectiveness (PE, the incidence of failed drilling) were calculated to track predator–prey interactions. Genus-level diversity increased through the Tjörnes deposits, in part related to a shift from intertidal to sublittoral environments. DF increased and PE decreased significantly between the pre-invasion and Serripes zones. However, DF decreased from the early to the late Serripes zone, which could signify stabilization of the Tjörnes community. An increase in competition among predators through the invasion is supported by an increase in abundance of naticids relative to bivalves, especially invasive species, a switch to smaller-sized bivalve prey, a decrease in naticid mean size and an increase in confamilial predation.

Using Logistic Regression to Identify Leading Factors to Prepare for an Earthquake Emergency during Daytime and Nighttime: The Case of Mass Earthquake Drills

Historical data have demonstrated that earthquakes can happen any time of the day and night. Drills may help communities to better prepare for such emergencies. A cross-sectional survey was conducted from 4 October to 20 November 2017, in Mexico City. The sample size was 2400. The addressed research questions were “what factors predict the likelihood that respondents would report that they agree on conducting mass evacuation drills: (a) any time of the day and (b) any time at night?” The logistic regression technique was employed to identify the factors leading to the outcome. In relation to (a), five variables were significantly associated with the outcome, i.e., age, frequency of drills, warning time, knowledge on what to do, and “perception vulnerability city”. Regarding (b), five variables were also significantly associated with the outcome variable, i.e., age, level of education, frequency of drills, negative emotions, and fear of house/building collapsing. More generally, several drills should be conducted any time of the day and night; further, 50% of them should be announced and 50% unannounced. Furthermore, the time of earthquake drills should be randomly selected. In this way, we may just match the spatial–temporal dimension of an earthquake emergency. It is hoped that the findings will lead to better preparedness of the residents of the capital city during an earthquake occurrence.

Research on energy absorption effect of double damping system of high-power hydraulic rock drill

ABSTRACT The high-power hydraulic rock drill is the key to the development of modern hydraulic drill rig. With the increase of power and frequency of new type rock drill, the rebound of drill tool will be obvious during drilling, which will seriously affect the structural safety and operation efficiency. For this phenomenon, it is necessary to research the characteristics of double damping system to absorb the rebound energy of drill tool. A new model of incident stress wave is revised on the basis of rectangular wave. By combining the reflected stress wave with the model of damping system, the pressure fluctuation of damping system is analysed. Based on the theory of stress wave transmission, the rebound model of drill tool is established, and the transmission law of incident wave and reflection wave in drilling process is analysed. The stress wave experiment was designed and the incident wave shape was obtained by testing. Based on the experimental results, the incident wave in the rebound model is corrected by Fourier transform principle. The accumulator model and the double damping internal structure model are established. The two parameters that can independently change the energy absorption effect of the double damping system are summarised.

Effectiveness of small size against drilling predation: Insights from lower Miocene faunal assemblage of Quilon Limestone, India

The nature of drilling predation, although well documented for molluscan fossils, is understudied for micromolluscs (<5 mm). Studying predation in micromolluscs is especially critical in evaluating the adaptive significance of small size against predation and assessing the evolutionary implication of predator-prey size relationship (PPSR). This study documents a drilling predation event in microbivalves from the lower Miocene (Burdigalian) fossil assemblage of Quilon Limestone from Kerala, India. Our sample of over 2000 valves represents nine families with an average drilling frequency (DF) of 0.06 and an incomplete drilling frequency (IDF) of 0.26. The characteristic drillhole morphology and occurrence of five genera of modern drilling gastropods (Naticid: Natica, Tanea and Polinices; Muricid: Triplex and Dermomurex) from the same locality reveal the predator identity. Predation in the studied assemblage is found to be highly selective in terms of prey taxa, size, mobility and site selection. Six out of nine families show predatory drilling indicating taxon selectivity. Poor correlation between DF and abundance further supports this view. Failed attacks are strongly correlated with morphological features such as surface ornamentation (Lucinidae) and presence of conchiolin layers (Corbulidae). Drilling occurs primarily on medium size class; prey outside this size range show lower rates of attack. This indicates the existence of a “negative size refugia” for extremely small prey along with the classical size refugia existing for large prey. Mobility is found to be an effective defense against drilling predation.Microbenthos of the Quilon Limestone shows a lower predation intensity in comparison to the Miocene macrobenthos worldwide including coeval formations of the Kutch Basin. The interaction in the microbenthos is more strongly size-dependent in contrast to the Kutch fauna. Reduced predation intensity in the microfauna and the existence of “negative size refugia” support the claim of micromorphy acting as a defense mechanism and highlights the role of size-dependent predation in marine benthos.