A generalized nonlinear three-dimensional Hoek‒Brown failure criterion

To understand the strengths of rocks under complex stress states,a generalized nonlinear threedimensional(3D)Hoek‒Brown failure(NGHB)criterion was proposed in this study.This criterion shares the same parameters with the generalized HB(GHB)criterion and inherits the parameter advantages of GHB.Two new parameters,b,and n,were introduced into the NGHB criterion that primarily controls the deviatoric plane shape of the NGHB criterion under triaxial tension and compression,respectively.The NGHB criterion can consider the influence of intermediate principal stress(IPS),where the deviatoric plane shape satisfies the smoothness requirements,while the HB criterion not.This criterion can degenerate into the two modified 3D HB criteria,the Priest criterion under triaxial compression condition and the HB criterion under triaxial compression and tension condition.This criterion was verified using true triaxial test data for different parameters,six types of rocks,and two kinds of in situ rock masses.For comparison,three existing 3D HB criteria were selected for performance comparison research.The result showed that the NGHB criterion gave better prediction performance than other criteria.The prediction errors of the strength of six types of rocks and two kinds of in situ rock masses were in the range of 2.0724%-3.5091%and 1.0144%-3.2321%,respectively.The proposed criterion lays a preliminary theoretical foundation for prediction of engineering rock mass strength under complex in situ stress conditions.

Nonlinear empirical failure criterion for rocks under triaxial compression

Based on existing triaxial compression experimental data,a new empirical failure criterion with wide applicability was proposed considering hydrostatic pressure,second stress invariance,and maximum shear stress.Four fitting evaluation indicators were used to verify the consistency of the new failure criterion,and the differences with the other 6 failure criteria were discussed.The characteristics of the new failure criteria in the principal stress space were finally analyzed.The results indicate that(1)the new failure criterion exhibits strong predictive ability for triaxial experiments and has good applicability for both intact and jointed rocks;(2)the influence of hydrostatic pressure on the failure surface exhibits a non-linear trend,and different hydrostatic pressure also exhibits different distribution patterns on the deviatoric stress plane,with a distribution characteristic pattern of hexagonal snowflake-regular hexagon.The maximum shear stress has a torsional effect on the new criterion,in the three-dimensional failure surface.The parameters a and b of the rock have an impact on the failure surface morphology of the new criterion function on the offset surface.

Estimating shear strength of high-level pillars supported with cemented backfilling using the HoekeBrown strength criterion

Deep metal mines are often mined using the high-level pillars with subsequent cementation backfilling(HLSCB)mining method.At the design stage,it is therefore important to have a reasonable method for determining the shear strength of the high-level pillars(i.e.cohesion and internal friction angle)when they are supported by cemented backfilling.In this study,a formula was derived for the upper limit of the confining pressure σ3max on a high-level pillar supported by cemented backfilling in a deep metal mine.A new method of estimating the shear strength of such pillars was then proposed based on the Hoek eBrown failure criterion.Our analysis indicates that the horizontal stress σhh acting on the cemented backfill pillar can be simplified by expressing it as a constant value.A reasonable and effective value for σ3max can then be determined.The value of s3max predicted using the proposed method is generally less than 3 MPa.Within this range,the shear strength of the high-level pillar is accurately calculated using the equivalent MohreCoulomb theory.The proposed method can effectively avoid the calculation of inaccurate shear strength values for the high-level pillars when the original HoekeBrown criterion is used in the presence of large confining pressures,i.e.the situation in which the cohesion value is too large and the friction angle is too small can effectively be avoided.The proposed method is applied to a deep metal mine in China that is being excavated using the HLSCB method.The shear strength parameters of the high-level pillars obtained using the proposed method were input in the numerical simulations.The numerical results show that the recommended level heights and sizes of the high-level pillars and rooms in the mine are rational.

Dosage Formula in Anesthesia for Manual Intrauterine Aspiration Post-Abortion in Resource-Limited Settings

Setting: Provincial General Reference Hospital of Bukavu, General Reference Hospital of Panzi, General Reference Hospital of Ciriri, General Reference Hospital of Nyatende and Biopharm Hospital Center. Objective: Contribute to the improvement of the anesthetic ECP of patients benefiting from MVA for incomplete abortion, Describe the methodology used for adoption of the dosage formula in Anesthesia for MVA, present the mathematical demonstration leading to the dosage formula in anesthesia for MVA. Materials and Methods: Our study was descriptive by mathematical demonstration of obtaining the equilibrium constant of the dosage formula of bipuvacaine 0.1% and Fentanyl 50 µg% adapted to the weight and specific size of patients treated anesthetically in MVA cases for incomplete abortion. We also carried out an operational research by first determining the interval where our equilibrium constant is included and secondly by means of the ends of the intervals found correlated to the ends of intervals of possible weights and sizes in the being normal human female of childbearing age to arrive at the real numerical value of the equilibrium constant of the BUKAVU Dosage Formula in the case of anesthesia for MVA during the management of incomplete abortions. Results: TWO-STAGE OPERATIONAL RESEARCH: • Determination of the interval where the equilibrium constant x = −0.95 x x by crossing the means between the extremes of volumes of anesthetic drugs giving a satisfactory sensory block without hemodynamic disturbance and the extremes of normal weight and height for women of childbearing age. We ended up with X = 0.37. Conclusion: At the end of our study which had the general objectives of contributing to the improvement of the anesthetic PEC of patients receiving MVA for incomplete abortion and specific objectives of describing the methodology used for adoption of the dosage formula in Anesthesia for MVA and present the mathematical demonstration which resulted in the dosage formula in nesthesia for MVA, it appears that the dosage formula of Bukavu, in case of intrathecal spinal analgesia of MVA for incomplete abortion provides precision on the specificity of the doses of bipuvacaine hypobarre 0.1% and Fentanyl 50 µg% reported to each patient according to her weight and height. Its application could therefore reduce morbidity and mortality and improve patient-practitioner comfort in the event of MVA for incomplete abortion following the dosage precision it provides.

Rockburst criterion and evaluation method for potential rockburst pit depth considering excavation damage effect

Excavation-induced disturbances in deep tunnels will lead to deterioration of rock properties and formation of excavation damaged zone(EDZ).This excavation damage effect may affect the potential rockburst pit depth.Taking two diversion tunnels of Jinping II hydropower station for example,the relationship between rockburst pit depth and excavation damage effect is first surveyed.The results indicate that the rockburst pit depth in tunnels with severe damage to rock masses is relatively large.Subsequently,the excavation-induced damage effect is characterized by disturbance factor D based on the Hoek-Brown criterion and wave velocity method.It is found that the EDZ could be further divided into a high-damage zone(HDZ)with D=1 and weak-damage zone(WDZ),and D decays from one to zero linearly.For this,a quantitative evaluation method for potential rockburst pit depth is established by presenting a three-element rockburst criterion considering rock strength,geostress and disturbance factor.The evaluation results obtained by this method match well with actual observations.In addition,the weakening of rock mass strength promotes the formation and expansion of potential rockburst pits.The potential rockburst pit depth is positively correlated with HDZ and WDZ depths,and the HDZ depth has a significant contribution to the potential rockburst pit depth.

Transient Stability Analysis of Converter-based Islanded Microgrids Based on Iterative Equal Area Criterion Considering Reactive Power Loop Dynamics and Varying Damping

With the rapid increase in the installed capacity of renewable energy in modern power systems,the stable operation of power systems with considerable power electronic equipment requires further investigation.In converter-based islanded mi-crogrid(CIM)systems equipped with grid-following(GFL)and grid-forming(GFM)voltage-source converters(VSCs),it is chal-lenging to maintain stability due to the mutual coupling effects between different VSCs and the loss of voltage and frequency sup-port from the power system.In previous studies,quantitative transient stability analysis was primarily used to assess the active power loop of GFM-VSCs.However,frequency and voltage dy-namics are found to be strongly coupled,which strongly affects the estimation result of stability boundary.In addition,the vary-ing damping terms have not been fully captured.To bridge these gaps,this paper investigates the transient stability of CIM consid-ering reactive power loop dynamics and varying damping.First,an accuracy-enhanced nonlinear model of the CIM is derived based on the effects of reactive power loop and post-disturbance frequency jump phenomena.Considering these effects will elimi-nates the risk of misjudgment.The reactive power loop dynamics make the model coefficients be no longer constant and thus vary with the power angle.To evaluate quantitatively the effects of re-active power loop and varying damping on the transient stability of CIM,an iterative criterion based on the equal area criterion theory is proposed.In addition,the effects of parameters on the stable boundary of power system are analyzed,and the dynamic interaction mechanisms are revealed.Simulation and experiment results verify the merits of the proposed method.

Prediction model establishment and validation for enteral nutrition aspiration during hospitalization in patients with acute pancreatitis

BACKGROUND Acute pancreatitis(AP)is a disease caused by abnormal activation of pancreatic enzymes and can lead to self-digestion of pancreatic tissues and dysfunction of other organs.Enteral nutrition plays a vital role in the treatment of AP because it can meet the nutritional needs of patients,promote the recovery of intestinal function,and maintain the barrier and immune functions of the intestine.However,the risk of aspiration during enteral nutrition is high;once aspiration occurs,it may cause serious complications,such as aspiration pneumonia,and suffocation,posing a threat to the patient’s life.This study aims to establish and validate a prediction model for enteral nutrition aspiration during hospitalization in patients with AP.AIM To establish and validate a predictive model for enteral nutrition aspiration during hospitalization in patients with AP.METHODS A retrospective review was conducted on 200 patients with AP admitted to Chengdu Shangjin Nanfu Hospital,West China Hospital of Sichuan University from January 2020 to February 2024.Clinical data were collected from the electronic medical record system.Patients were randomly divided into a validation group(n=40)and a modeling group(n=160)in a 1:4 ratio,matched with 200 patients from the same time period.The modeling group was further categorized into an aspiration group(n=25)and a non-aspiration group(n=175)based on the occurrence of enteral nutrition aspiration during hospitalization.Univariate and multivariate logistic regression analyses were performed to identify factors influencing enteral nutrition aspiration in patients with AP during hospitalization.A prediction model for enteral nutrition aspiration during hospitalization was constructed,and calibration curves were used for validation.Receiver operating characteristic curve analysis was conducted to evaluate the predictive value of the model.RESULTS There was no statistically significant difference in general data between the validation and modeling groups(P>0.05).The comparison of age,gender,body mass index,smoking history,hypertension history,and diabetes history showed no statistically significant difference between the two groups(P>0.05).However,patient position,consciousness status,nutritional risk,Acute Physiology and Chronic Health Evaluation(APACHE-II)score,and length of nasogastric tube placement showed statistically significant differences(P<0.05)between the two groups.Multivariate logistic regression analysis showed that patient position,consciousness status,nutritional risk,APACHE-II score,and length of nasogastric tube placement were independent factors influencing enteral nutrition aspiration in patients with AP during hospitalization(P<0.05).These factors were incorporated into the prediction model,which showed good consistency between the predicted and actual risks,as indicated by calibration curves with slopes close to 1 in the training and validation sets.Receiver operating characteristic analysis revealed an area under the curve(AUC)of 0.926(95%CI:0.8889-0.9675)in the training set.The optimal cutoff value is 0.73,with a sensitivity of 88.4 and specificity of 85.2.In the validation set,the AUC of the model for predicting enteral nutrition aspiration in patients with AP patients during hospitalization was 0.902,with a standard error of 0.040(95%CI:0.8284-0.9858),and the best cutoff value was 0.73,with a sensitivity of 91.9 and specificity of 81.8.CONCLUSION A prediction model for enteral nutrition aspiration during hospitalization in patients with AP was established and demonstrated high predictive value.Further clinical application of the model is warranted.

Enhanced Hoek-Brown(H-B)criterion for rocks exposed to chemical corrosion

Underground constructions often encounter water environments,where water–rock interaction can increase porosity,thereby weakening engineering rocks.Correspondingly,the failure criterion for chemically corroded rocks becomes essential in the stability analysis and design of such structures.This study enhances the applicability of the Hoek-Brown(H-B)criterion for engineering structures operating in chemically corrosive conditions by introducing a kinetic porosity-dependent instantaneous mi(KPIM).A multiscale experimental investigation,including nuclear magnetic resonance(NMR),X-ray diffraction(XRD),scanning electron microscopy(SEM),pH and ion chromatography analysis,and triaxial compression tests,is employed to quantify pore structural changes and their linkage with the strength responses of limestone under coupled chemical-mechanical(C-M)conditions.By employing ion chromatography and NMR analysis,along with incorporating the principles of free-face dissolution theory accounting for both congruent and incongruent dissolution,a kinetic chemical corrosion model is developed.This model aims to calculate the kinetic porosity alterations within rocks exposed to varying H+concentrations and durations.Subsequently,utilizing the generalized mixture rule(GMR),the kinetic porositydependent mi is formulated.Evaluation of the KPIM-enhanced H-B criterion using compression test data from 5 types of rocks demonstrated a high level of consistency between the criterion and the experimental results,with a coefficient of determination greater than 0.96,a mean absolute percentage error less than 4.84%,and a root-mean-square deviation less than 5.95 MPa.Finally,the physical significance of the porosity-dependent instantaneous mi is clarified:it serves as an indicator of a rock’s capacity to leverage the confining pressure effect.

Strength criterion for crystalline rocks considering grain size effect and tensile-compressive strength ratio

The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the strength.However,most strength criteria neglect the strength variations caused by different grain characteristics in rocks.Furthermore,the traditional linear criteria tend to overestimate tensile strength and exhibit apex singularity.To address these shortcomings,a piecewise strength criterion that considers the grain size effect has been proposed.A part of an ellipse was employed to construct the envelope of the tensive-shear region on the meridian plane,to accurately reproduce the low tensile-compressive strength ratio.Based on the analysis of experimental data,both linear and exponential modification functions that account for grain size effects were integrated into the proposed criterion.The corresponding finite element algorithm has been implemented.The accuracy and applicability of the proposed criterion were validated by comparing with the experimental data.

Maximum Correntropy Criterion-Based UKF for Loosely Coupling INS and UWB in Indoor Localization

Indoor positioning is a key technology in today’s intelligent environments,and it plays a crucial role in many application areas.This paper proposed an unscented Kalman filter(UKF)based on the maximum correntropy criterion(MCC)instead of the minimummean square error criterion(MMSE).This innovative approach is applied to the loose coupling of the Inertial Navigation System(INS)and Ultra-Wideband(UWB).By introducing the maximum correntropy criterion,the MCCUKF algorithm dynamically adjusts the covariance matrices of the system noise and the measurement noise,thus enhancing its adaptability to diverse environmental localization requirements.Particularly in the presence of non-Gaussian noise,especially heavy-tailed noise,the MCCUKF exhibits superior accuracy and robustness compared to the traditional UKF.The method initially generates an estimate of the predicted state and covariance matrix through the unscented transform(UT)and then recharacterizes the measurement information using a nonlinear regression method at the cost of theMCC.Subsequently,the state and covariance matrices of the filter are updated by employing the unscented transformation on the measurement equations.Moreover,to mitigate the influence of non-line-of-sight(NLOS)errors positioning accuracy,this paper proposes a k-medoid clustering algorithm based on bisection k-means(Bikmeans).This algorithm preprocesses the UWB distance measurements to yield a more precise position estimation.Simulation results demonstrate that MCCUKF is robust to the uncertainty of UWB and realizes stable integration of INS and UWB systems.

Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.

Fine-needle aspiration technique under endoscopic ultrasound guidance:A technical approach for RNA profiling of pancreatic neoplasms

BACKGROUND Early diagnosis of pancreatic ductal adenocarcinoma(PDAC)has been a longstanding challenge.The prognosis of patients with PDAC depends on the stage at diagnosis.It is necessary to identify biomarkers for the detection and differentiation of pancreatic tumors and optimize PDAC sample preparation procedures for DNA and RNA analysis.Most molecular studies are done using paraffin-embedded blocks;however,the integrity of DNA and RNA is often compromised in this format.Moreover,RNA isolated from human pancreatic tissue samples is generally of low quality,in part,because of the high concentration of endogenous pancreatic RNAse activity present.AIM To assess the potential of endoscopic ultrasound-guided fine-needle aspiration(EUS-FNA)to obtain specimens from pancreatic neoplasms for subsequent RNA molecular profiling,including next-generation sequencing(NGS).METHODS Thirty-four EUS-FNA samples were included in this study:PDAC(n=15),chronic pancreatitis(n=5),pancreatic cysts(n=14),mucinous cysts(mucinous cystic neoplasia/intraductal papillary mucinous neoplasia)n=7,serous cystic neoplasms n=5,and pseudocysts n=2.Cyst material consisted of cyst fluid and cyst wall samples obtained by through-the-needle biopsy(TTNB).Samples were stored at -80℃ until analysis.RNA purity(A260/230,A260/280 ratios),concentration,and integrity(RIN)were assessed.Real-time polymerase chain reaction was conducted on all samples,and small RNA libraries were prepared from solid mass samples.RESULTS RNA was successfully extracted from 29/34(85%)EUS-FNA samples:100% pancreatic adenocarcinoma samples,100% chronic pancreatitis samples,70% pancreatic fluid cyst samples,and 50%TTNB samples.The relative expression of GAPDH and HPRT were obtained for all successfully extracted RNA samples(n=29)including lowquality RNA specimens.Low concentration and nonoptimal RIN values(no less than 3)of RNA extracted from EUS-FNA samples did not prevent NGS library preparation.The suitability of cyst fluid samples for RNA profiling varied.The quality of RNA extracted from mucinous cyst fluid had a median RIN of 7.7(5.0-8.2),which was compatible with that from solid neoplasms[6.2(0-7.8)],whereas the quality of the RNA extracted from all fluids of serous cystic neoplasms and TTNB samples had a RIN of 0.CONCLUSION The results demonstrate the high potential of EUS-FNA material for RNA profiling of various pancreatic lesions,including low-quality RNA specimens.

Flexible bronchoscopy for foreign body aspiration in children:A single-centre experience

BACKGROUND The technological evolution of bronchoscopy has led to the widespread adoption of flexible techniques and their use for both diagnostic and therapeutic purposes.Currently,there is an active debate regarding the comparative efficacy and safety of rigid vs flexible bronchoscopy in the treatment of foreign body aspiration.AIM To evaluate our experience with tracheobronchial foreign body extraction using flexible bronchoscopy and provide a literature overview.METHODS This was a single-centre retrospective study.Twenty-four patients were enrolled between January 2017 and January 2023.Medical records of patients aged below 18 years who were admitted to authors’affiliated institution with a suspected diagnosis of foreign body aspiration were collected from hospital’s database to Microsoft Excel 2019.Data were analysed using MedCalc Statistical Software.RESULTS Patient ages varied from 9 months to 11 years.The median age was 23.5 months,95%confidence interval(CI)19.49-44.77.We observed age clustering in children with foreign body aspiration at our institution with three age subgroups:(1)0-25 months;(2)40-60 months;and(3)120-140 months.We expectancy of an organic tracheobronchial foreign body was significantly higher in 0-25 months subgroup than that in older ones when subgroups 40-60 and 120-140 months were combined together(odds ratio=10.0,95%CI:1.44-29.26,P=0.0197).Successful foreign body extraction was performed in all cases.Conversion to a rigid bronchoscope was not required in any of the cases.No major complications(massive bleeding,tracheobronchial tree perforation,or asphyxia)were observed.CONCLUSION Flexible bronchoscopy is an effective and safe method for tracheobronchial foreign body extraction in children.

Application Effect of Stratified Nursing Intervention for ICU Mechanically Ventilated Patients in the Context of Aspiration Risk Assessment

Objective:To explore the application effect of stratified nursing intervention based on the background of misinspiration risk assessment in mechanically ventilated patients in intensive care unit(ICU).Methods:100 cases of mechanically ventilated patients who were admitted to the ICU of our hospital from March 2022 to March 2023 were selected and divided into an observation group and a control group according to the random number table method,with 50 cases in each of the two groups.The control group was given routine care in ICU,and the observation group was given stratified nursing interventions based on the background of the risk of aspiration assessment on the basis of the control group,and both groups were cared for until they were transferred out of the ICU,and the mechanical ventilation time,ICU stay time,muscle strength score,complication rate,adherence,and satisfaction were observed and compared between the two groups.Results:The mechanical ventilation time and ICU stay time of the observation group were shorter than that of the control group after the intervention;the muscle strength score,compliance and satisfaction of the observation group were higher than that of the control group after the intervention;and the complication rate of the observation group was lower than that of the control group after the intervention,all of which were P<0.05.Conclusion:The application of stratified nursing intervention based on the background of misaspiration risk assessment in ICU mechanically ventilated patients can improve the patient's muscle strength,shorten the time of mechanical ventilation,promote the patient's recovery,reduce the occurrence of complications,and improve the patient's compliance and satisfaction.

A failure criterion for shale considering the anisotropy and hydration based on the shear slide failure model

A failure criterion fully considering the anisotropy and hydration of shale is essential for shale formation stability evaluation.Thus,a novel failure criterion for hydration shale is developed by using Jaeger’s shear failure criterion to describe the anisotropy and using the shear strength reduction caused by clay minerals hydration to evaluate the hydration.This failure criterion is defined with four parameters in Jaeger’s shear failure criterion(S_(1),S_(2),a andφ),three hydration parameters(k,ω_(sh)andσ_(s))and two material size parameters(d and l0).The physical meanings and determining procedures of these parameters are described.The accuracy and applicability of this failure criterion are examined using the published experimental data,showing a cohesive agreement between the predicted values and the testing results,R^(2)=0.916 and AAREP(average absolute relative error percentage)of 9.260%.The error(|D_(p)|)is then discussed considering the effects ofβ(angle between bedding plane versus axial loading),moisture content and confining pressure,presenting that|Dp|increases whenβis closer to 30°,and|D_(p)|decreases with decreasing moisture content and with increasing confining pressure.Moreover,|D_(p)|is demonstrated as being sensitive to S1and being steady with decrease in the data set whenβis 0°,30°,45°and 90°.

Two-dimensional face stability analysis in rock masses governed by the Hoek-Brown strength criterion with a new multi-horn mechanism

The face stability problem is a major concern for tunnels excavated in rock masses governed by the Hoek-Brown strength criterion.To provide an accurate prediction for the theoretical solution of the critical face pressure,this study adopts the piecewise linear method(PLM)to account for the nonlinearity of the strength envelope and proposes a new multi-horn rotational mechanism based on the Hoek-Brown strength criterion and the associative flow rule.The analytical solution of critical support pressure is derived from the energy-work balance equation in the framework of the plastic limit theorem;it is formulated as a multivariable nonlinear optimization problem relying on 2m dependent variables(m is the number of segments).Meanwhile,two classic linearized measures,the generalized tangential technique(GTT)and equivalent Mohr-Coulomb parameters method(EMM),are incorporated into the analysis for comparison.Surprisingly,the parametric study indicates a significant improvement in support pressure by up to 13%compared with the GTT,and as expected,the stability of the tunnel face is greatly influenced by the rock strength parameters.The stress distribution on the rupture surface is calculated to gain an intuitive understanding of the failure at the limit state.Although the limit analysis is incapable of calculating the true stress distribution in rock masses,a rough approximation of the stress vector on the rupture surface is permitted.In the end,sets of normalized face pressure are provided in the form of charts for a quick assessment of face stability in rock masses.

Successful treatment of a rare subcutaneous emphysema after a blow-out fracture surgery using needle aspiration:A case report

BACKGROUND Many cases of emphysema associated with blow-out fractures occur before surgery due to trauma.However,emphysema can occur even after surgery,and most of such cases are managed conservatively and allowed to resolve.Swelling in the periorbital area due to emphysema that occurs after surgery can make early recovery difficult.CASE SUMMARY Herein,we describe a case of postoperative subcutaneous emphysema that was treated using a simple needle aspiration method.A 48-year-old male patient visited the hospital with a blow-out fracture of the left medial orbital wall and nasal bone fracture.One day postoperatively,swelling and crepitus in the left periorbital area were observed,and follow-up computed tomography showed emphysema in the left periorbital subcutaneous area.Needle aspiration using an 18-gauge needle and syringe was used to relieve the emphysema.The symptoms of sudden swelling improved immediately,and no recurrence was observed.CONCLUSION We conclude that needle aspiration is a useful method that could help in relieving symptom,resolving discomfort,and enabling early return to daily life in patients with postoperative subcutaneous emphysema.

Numerical simulation study on shear resistance of anchorage joints considering tensile-shear fracture criterion of 2G-NPR bolt

2G-NPR bolt (the 2nd generation Negative Poisson’s Ratio bolt) is a new type of bolt with high strength, high toughness and no yield platform. It has signifcant efects on improving the shear strength of jointed rock mass and controlling the stability of surrounding rock. To achieve an accurate simulation of bolted joint shear tests, we have studied a numerical simulation method that takes into account the 2G-NPR bolt's tensile–shear fracture criterion. Firstly, the indoor experimental study on the tensile–shear mechanical properties of 2G-NPR bolt is carried out to explore its mechanical properties under diferent tensile–shear angles, and the fracture criterion of 2G-NPR bolt considering the tensile–shear angle is established. Then, a three-dimensional numerical simulation method considering the tensile–shear mechanical constitutive and fracture criterion of 2G-NPR bolt, the elastoplastic mechanical behavior of surrounding rock and the damage and deterioration of grouting body is proposed. The feasibility and accuracy of the method are verifed by comparing with the indoor shear test results of 2G-NPR bolt anchorage joints. Finally, based on the numerical simulation results, the deformation and stress of the bolt, the distribution of the plastic zone of the rock mass, the stress distribution and the damage of the grouting body are analyzed in detail. The research results can provide a good reference value for the practical engineering application and shear mechanical performance analysis of 2G-NPR bolt.

Correction of dynamic Brazilian disc tensile strength of rocks under preloading conditions considering the overload phenomenon and invoking the Griffith criterion

Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test is the suggested method by the International Society for Rock Mechanics and Rock Engineering(ISRM)for measuring both the static and dynamic tensile strengths of rock-like materials.However,due to the overload phenomenon and the complex preloading conditions,the dynamic tensile strengths of rocks measured by the BD tests tend to be overestimated.To address this issue,the dynamic BD tensile strength(BTS)of Fangshan marble(FM)under different preloading conditions were measured through a triaxial split Hopkinson pressure bar(SHPB).The fracture onset in BD specimen was captured through a strain gage around the disc center.The discrepancy between the traditional tensile strength(TTS,determined by the peak load P_(f) of the BD specimen)and the nominal tensile strength(NTS,obtained from the load P_(i) when the diametral fracture commences in the tested BD specimen)was applied to quantitatively evaluating the overload phenomenon.The Griffith criterion was used to rectify the calculation of the tensile stress at the disc center under triaxial stress states.The results demonstrate that the overload ratio(s)increases with the loading rate(σ)and decreases with the hydrostatic pressure(σ_(s)).The TTS corrected by the Griffith criterion is independent of theσ_(s)due to the overload phenomenon,while the NTS corrected by the Griffith criterion is sensitive to both the andσ.Therefore,it is essential to modify the tensile stress in dynamic confined BD tests using both the overload correction and the Griffith criterion rectification to obtain the accurate dynamic BTS of rocks.

Aspirations of Fisherfolk Communities on Their Children’s Education in Albay, Asid, and Ragay Gulfs of Bicol, Philippines

The study explores the yearnings of fisherfolks on their child’s education, hindrances, and factors that shape their desire as parents. Field observations and key informant interview among elder members of fisherfolk communities surrounding the Albay, Ragay, and Asid Gulfs of the Bicol Region was utilized. The study revealed that the majority of the fisherfolk parents do not want their children to continue fishing as their main source of livelihood because of potential risks, hardships, and cultural factors like collectivism, close family ties, and dependence on the elders. The parents’ aspirations were shaped by their persistence over various threats, fears, personal unfulfilled dreams, and career opportunities thru education. Most of the parents desired a college education and a safe and secure profession for their children. The study deduced that these challenges can be a contributory factor for the declining number of fisherfolks surrounding the gulfs. Influencing this sector is the factor motivating fishers in their aspirations for their children’s education. The study recommends introducing strategies for fisherfolks to develop a strong sense of hope and drive in realizing their aspirations and further research on the impact of culture, the role of women and children, and fisherfolks and their success stories.