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Inflow and outflow permeability tests in a very soft clay under low stresses
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作者 J.W.S.Vargas F.A.B.Danziger +1 位作者 F.R.Lopes T.Lunne 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3270-3283,共14页
In situ inflow and outflow permeability tests with the BAT probe at SarapuíII soft clay test site are presented.A description of the BAT permeability test is provided,discussing its advantages and shortcomings,es... In situ inflow and outflow permeability tests with the BAT probe at SarapuíII soft clay test site are presented.A description of the BAT permeability test is provided,discussing its advantages and shortcomings,especially in the case of very soft clays under low stresses.Pore pressures were monitored during probe installation and were found to be slightly lower than piezocone u2 pore pressures,consistent with the position of the filter.The role of filter tip saturation was investigated after the usual saturation procedure provided an unsatisfactory pore pressure response during probe installation.Results show that the vacuum saturation procedure provides adequate response during installation and increases the reliability of the coefficient of permeability determination in early measurements.Both inflow and outflow tests yielded similar results,indicating that careful execution of the test can lead to good test repeatability regardless of the loading condition.Various sequences of alternated inflow and outflow tests have yielded similar results,indicating that soil reconsolidation and filter clogging were negligible in the tests performed.Data are presented concerning the relationship between index parameters and the in situ coefficient of permeability for SarapuíII clay,which plot outside the range of existing databases. 展开更多
关键词 Permeability test Soft clay BAT probe Inflow and outflow tests
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Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints
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作者 Guiyun Gao Chenghu Wang Ke Gao 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第5期1637-1648,共12页
The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor determination.However,the stress tensor determinati... The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor determination.However,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable results.In this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests required.Different shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo method.Thereafter,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress constraints.The inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress tensor.Two stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)method.The results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress gradient.The inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints employed.The M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole. 展开更多
关键词 Stress tensor Hydraulic tests on pre-existing fractures Mean stress Stress constraint Hydraulic fracturing
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Small-scale fire tests in the underwater tunnel section model with new sidewall smoke extraction
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作者 Shunyu Yue Ruifeng Miao +2 位作者 Huihang Cheng Maohua Zhong Xiujun Yang 《Deep Underground Science and Engineering》 2024年第2期247-254,共8页
The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the t... The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels. 展开更多
关键词 sidewall smoke extraction system small‐scale fire tests smoke control
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Scoring and Consequential Validity Evidence of Computer-and Paper-Based Writing Tests in Times of Change
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作者 María GUAPACHA-CHAMORRO Orlando CHAVES-VARÓN 《Chinese Journal of Applied Linguistics》 2024年第3期450-480,525,共32页
Little is known about how the assessment modality,i.e.,computer-based(CB)and paper-based(PB)tests,affects language teachers’scorings,perceptions,and preferences and,therefore,the validity and fairness of classroom wr... Little is known about how the assessment modality,i.e.,computer-based(CB)and paper-based(PB)tests,affects language teachers’scorings,perceptions,and preferences and,therefore,the validity and fairness of classroom writing assessments.The present mixed-methods study used Shaw and Weir’s(2007)sociocognitive writing test validation framework to examine the scoring and consequential validity evidence of CB and PB writing tests in EFL classroom assessment in higher education.Original handwritten and word-processed texts of 38 EFL university students were transcribed to their opposite format and assessed by three language lecturers(N=456 texts,152 per teacher)to examine the scoring validity of CB and PB tests.The teachers’perceptions of text quality and preferences for assessment modality accounted for the consequential validity evidence of both tests.Findings revealed that the assessment modality impacted teachers’scorings,perceptions,and preferences.The teachers awarded higher scores to original and transcribed handwritten texts,particularly text organization and language use.The teachers’perceptions of text quality differed from their ratings,and physical,psychological,and experiential characteristics influenced their preferences for assessment modality.The results have implications for the validity and fairness of CB and PB writing tests and teachers’assessment practices. 展开更多
关键词 scoring validity consequential validity CB and PB writing tests classroom assessment
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Entangled relationship:Chinese parents’involvement in young learners’English tests
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作者 GUO JIA CHENG LIYING 《语言测试与评价》 2024年第1期1-20,112,共21页
Young learners’English(YLE)tests have become increasingly prevalent among and important to Chinese English learners and their parents.In China,parents are actively involved in their children’s education and test-tak... Young learners’English(YLE)tests have become increasingly prevalent among and important to Chinese English learners and their parents.In China,parents are actively involved in their children’s education and test-taking decisions,and their participation has given rise to a series of social impacts.Although parent involvement has received increasing public and academic attention in newspaper and scholarly articles,there exists no thorough analysis of current research on parents’roles in young learners’test-taking.To address this gap,we systemically analyzed Chinese newspaper articles and academic articles between 2011 and 2021 to elicit Chinese parents’roles in YLE test-taking.Our thematic analysis of the literature identifies the ways in which parents influence their children’s test-taking experiences,and how the tests affect this influence.Specifically,our results elicit 1)parents’engagement in YLE testing;2)parents’understanding of the intended uses of YLE tests;3)parents’perception and consequences of their involvement in YLE testing;and 4)parents’backgrounds.This analysis reveals the popularity of YLE tests among young learners and their parents in China and public concern over test-related issues.It also broadens our understanding of YLE testing impact and suggests future potential research directions. 展开更多
关键词 young learners’English(YLE)tests in China parents’roles test impact
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Real-world utility of serological tests in patients with suspected scrub typhus in the Republic of Korea:A single-center,retrospective,observational study
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作者 Seulki Kim A Reum Kim +2 位作者 Seungjin Lim Su Jin Lee Moonsuk Bae 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2024年第6期273-280,I0004,I0005,共10页
Objective:Serological tests are widely used for scrub typhus diagnosis;however,their limitations are evident.This study aims to assess their practical value in clinical settings.Methods:We analyzed the data of adult p... Objective:Serological tests are widely used for scrub typhus diagnosis;however,their limitations are evident.This study aims to assess their practical value in clinical settings.Methods:We analyzed the data of adult patients with suspected scrub typhus who visited a tertiary care hospital in the Republic of Korea from September to December from 2019 to 2021.The included patients had an acute fever and at least one of the following ten secondary findings:myalgia,skin rash,eschar,headache,thrombocytopenia,increased liver enzyme levels,lymphadenopathy,hepatomegaly,splenomegaly,and pleural effusion.The diagnoses were grouped as scrub typhus or other diseases by two infectious disease physicians.Results:Among 136 patients who met the eligibility criteria,109 had scrub typhus and 27 had different diseases.Single and paired total antibodies using immunofluorescence assay(IFA),and total antibodies using immunochromatography-based rapid diagnostic testing(ICT)were measured in 98%,22%,and 75%of all patients,respectively.Confirmation using paired samples for scrub typhus was established at a median of 11[interquartile range(IQR)10-16]days following the first visit.Among the 82 admitted patients,the median admission time was 9(IQR 7-13)days.According to IFA,58(55%)patients with scrub typhus had total immunoglobulin titers≥1:320,while 23(85%)patients with other disease had titers<1:320.Positive ICT results were observed in 64(74%)patients with scrub typhus and 10(67%)patients with other diseases showed negative ICT results.Conclusions:Serological testing for scrub typhus is currently insufficient for decision-making in clinical practice. 展开更多
关键词 Scrub typhus Serological test Immunofluorescence assay IMMUNOCHROMATOGRAPHY Rapid detecting test
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Research on aiming methods for small sample size shooting tests of two-dimensional trajectory correction fuse
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作者 Chen Liang Qiang Shen +4 位作者 Zilong Deng Hongyun Li Wenyang Pu Lingyun Tian Ziyang Lin 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第3期506-517,共12页
The longitudinal dispersion of the projectile in shooting tests of two-dimensional trajectory corrections fused with fixed canards is extremely large that it sometimes exceeds the correction ability of the correction ... The longitudinal dispersion of the projectile in shooting tests of two-dimensional trajectory corrections fused with fixed canards is extremely large that it sometimes exceeds the correction ability of the correction fuse actuator.The impact point easily deviates from the target,and thus the correction result cannot be readily evaluated.However,the cost of shooting tests is considerably high to conduct many tests for data collection.To address this issue,this study proposes an aiming method for shooting tests based on small sample size.The proposed method uses the Bootstrap method to expand the test data;repeatedly iterates and corrects the position of the simulated theoretical impact points through an improved compatibility test method;and dynamically adjusts the weight of the prior distribution of simulation results based on Kullback-Leibler divergence,which to some extent avoids the real data being"submerged"by the simulation data and achieves the fusion Bayesian estimation of the dispersion center.The experimental results show that when the simulation accuracy is sufficiently high,the proposed method yields a smaller mean-square deviation in estimating the dispersion center and higher shooting accuracy than those of the three comparison methods,which is more conducive to reflecting the effect of the control algorithm and facilitating test personnel to iterate their proposed structures and algorithms.;in addition,this study provides a knowledge base for further comprehensive studies in the future. 展开更多
关键词 Two-dimensional trajectory correction fuse Small sample size test Compatibility test KL divergence Fusion bayesian estimation
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Resistance of full-scale beams against close-in explosions.Numerical modeling and field tests
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作者 A.Prado A.Alañón +5 位作者 R.Castedo A.P.Santos L.M.López M.Chiquito M.Bermejo C.Oggeri 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第10期35-47,共13页
This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading. Field test data has been used to compare ... This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading. Field test data has been used to compare model results for each case. The numerical modelling has been, carried out using the suitable code LS-DYNA. This code integrates blast load routine(CONWEP) for the explosive description and four different material models for the concrete including: Karagozian & Case Concrete, Winfrith, Continuous Surface Cap Model and Riedel-Hiermaier-Thoma models, with concrete meshing based on 10, 15, and 20 mm. Six full-scale beams were tested: four of them used for the initial calibration of the numerical model and two more tests at lower scaled distances. For calibration, field data obtained employing pressure and accelerometers transducers were compared with the results derived from the numerical simulation. Damage surfaces and the shape of rupture in the beams have been used as references for comparison. Influence of the meshing on accelerations has been put in evidence and for some models the shape and size of the damage in the beams produced maximum differences around 15%. In all cases, the variations between material and mesh models are shown and discussed. 展开更多
关键词 Blast test Numerical simulation LS-DYNA Concrete model Mesh effect Full-scale beams
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Dynamic response of mountain tunnel,bridge,and embankment along the Sichuan-Tibet transportation corridor to active fault based on model tests
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作者 HUANG Beixiu QIAO Sijia +2 位作者 CHEN Xulei LI Lihui QI Shengwen 《Journal of Mountain Science》 SCIE CSCD 2024年第1期182-199,共18页
The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes.While extensive studies have individually explored the effect of active faults and strong earthquakes on dif... The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes.While extensive studies have individually explored the effect of active faults and strong earthquakes on different engineering structures,their combined effect remains unclear.This research employed multiple physical model tests to investigate the dynamic response of various engineering structures,including tunnels,bridges,and embankments,under the simultaneous influence of cumulative earthquakes and stick-slip misalignment of an active fault.The prototype selected for this study was the Kanding No.2 tunnel,which crosses the Yunongxi fault zone within the Sichuan-Tibet transportation corridor.The results demonstrated that the tunnel,bridge,and embankment exhibited amplification in response to the input seismic wave,with the amplification effect gradually decreasing as the input peak ground acceleration(PGA)increased.The PGAs of different engineering structures were weakened by the fault rupture zone.Nevertheless,the misalignment of the active fault may decrease the overall stiffness of the engineering structure,leading to more severe damage,with a small contribution from seismic vibration.Additionally,the seismic vibration effect might be enlarged with the height of the engineering structure,and the tunnel is supposed to have a smaller PGA and lower dynamic earth pressure compared to bridges and embankments in strong earthquake zones crossing active faults.The findings contribute valuable insights for evaluating the dynamic response of various engineering structures crossing an active fault and provide an experimental reference for secure engineering design in the challenging conditions of the Sichuan-Tibet transportation corridor. 展开更多
关键词 Dynamic response Engineering structure Sichuan-Tibet transportation corridor Active fault EARTHQUAKE Model test
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Optimal Design of High-Speed Partial Flow Pumps using Orthogonal Tests and Numerical Simulations
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作者 Jiaqiong Wang Tao Yang +2 位作者 Chen Hu Yu Zhang Ling Zhou 《Fluid Dynamics & Materials Processing》 EI 2024年第6期1203-1218,共16页
To investigate the influence of structural parameters on the performances and internal flow characteristics of partial flow pumps at a low specific speed of 10000 rpm,special attention was paid to the first and second... To investigate the influence of structural parameters on the performances and internal flow characteristics of partial flow pumps at a low specific speed of 10000 rpm,special attention was paid to the first and second stage impeller guide vanes.Moreover,the impeller blade outlet width,impeller inlet diameter,blade inclination angle,and number of blades were considered for orthogonal tests.Accordingly,nine groups of design solutions were formed,and then used as a basis for the execution of numerical simulations(CFD)aimed at obtaining the efficiency values and heads for each design solution group.The influence of impeller geometric parameters on the efficiency and head was explored,and the“weight”of each factor was obtained via a range analysis.Optimal structural parameters were finally chosen on the basis of the numerical simulation results,and the performances of the optimized model were verified accordingly(yet by means of CFD).Evidence is provided that the increase in the efficiency and head of the optimized model was 12.11%and 23.5 m,respectively,compared with those of the original model. 展开更多
关键词 HIGH-SPEED partial flow pump orthogonal test optimal design numerical calculation
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Evaluation of the effects of EPS composite soil replacement on the dynamic performance of caisson structure using shaking table tests
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作者 Gao Hongmei Ji Zhanpeng +3 位作者 Zhang Xinlei Zhang Shushan Wang Zhihua Shen Guangming 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第4期829-843,共15页
The seismic performance of a caisson structure under two types of models with a saturated sandy foundation(CSS)and an expanded polystyrene(EPS)composite soil foundation(CES)are studied using shaking table tests.The ma... The seismic performance of a caisson structure under two types of models with a saturated sandy foundation(CSS)and an expanded polystyrene(EPS)composite soil foundation(CES)are studied using shaking table tests.The macro phenomena of the two different foundation models are described and analyzed.The effects of the replacement of EPS composite soil on seismic-induced liquefaction of backfill and the dynamic performance of a caisson structure are evaluated in detail.The results show that the excess pore water pressure generation in the CES is significantly slower than that in the CSS during the shaking.The dynamic earth pressure acting on the caisson has a triangular shape.The response of horizontal acceleration,displacement,settlement,and rotation angle of the caisson in the CES is smaller than that in the CSS,which means the caisson in the CES has a better seismic performance.Furthermore,the out-of-phase phenomenon between dynamic earth thrust and inertial force in the CES is more obvious than that in the CSS,which is beneficial to reduce the lateral force and improve the stability of the caisson structure. 展开更多
关键词 EPS composite soil foundation Caisson-type quay wall shaking table test phase difference rotation angle
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Novel Method for Evaluating the Aging of Aviation Turbine Engine Oils via High-Temperature Bearing Deposit Tests
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作者 Hao Lichun Yang He +3 位作者 Song Haiqing Zhou Yunfan He Jingjian Liang Yuxiang 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2024年第1期67-77,共11页
Aviation turbine engine oils require excellent thermal-oxidative stability because of their high-temperature environments.High-temperature bearing deposit testing is a mandatory method for measuring the thermal-oxidat... Aviation turbine engine oils require excellent thermal-oxidative stability because of their high-temperature environments.High-temperature bearing deposit testing is a mandatory method for measuring the thermal-oxidative performance of aviation lubricant oils,and the relevant apparatus was improved in the present study.Two different commercial aviation turbine engine oils were tested,one with standard performance(known as the SL oil)and the other with high thermal stability,and their thermal-oxidative stability characteristics were evaluated.After 100 h of high-temperature bearing testing,the SL oil was analyzed by using various analytical techniques to investigate its thermal-oxidative process in the bearing test,with its thermal-oxidative degradation mechanism also being discussed.The results indicate that the developed high-temperature bearing apparatus easily meets the test requirements of method 3410.1 in standard FED-STD-791D.The viscosity and total acid number(TAN)of the SL oil increased with the bearing test time,and various deposits were produced in the bearing test,with the micro-particles of the carbon deposits being sphere-like,rod-like,and sheet-like in appearance.The antioxidant additives in the oil were consumed very rapidly in the first 30 h of the bearing test,with N-phenyl-1-naphthylamine being consumed faster than dioctyldiphenylamine.Overall,the oil thermal-oxidative process involves very complex physical and chemical mechanisms. 展开更多
关键词 aviation turbine engine oil high-temperature bearing deposit test thermal-oxidative degradation antioxidant additives
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Significance of oxidative stress and antioxidant capacity tests as biomarkers of premature ovarian insufficiency: A case control study
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作者 Kaoru Kakinuma Toshiyuki Kakinuma 《World Journal of Clinical Cases》 SCIE 2024年第3期479-487,共9页
BACKGROUND Premature ovarian insufficiency(POI)is a condition that causes secondary amenorrhea owing to ovarian hypofunction at an early stage.Early follicular depletion results in intractable infertility,thereby cons... BACKGROUND Premature ovarian insufficiency(POI)is a condition that causes secondary amenorrhea owing to ovarian hypofunction at an early stage.Early follicular depletion results in intractable infertility,thereby considerably reducing the quality of life of females.Given the continuum in weakened ovarian function,progressing from incipient ovarian failure(IOF)to transitional ovarian failure and further to POI,it is necessary to develop biomarkers for predicting POI.The oxidative stress states in IOF and POI were comprehensively evaluated via oxidative stress[diacron-reactive oxygen metabolites(d-ROMs)]test and anti-oxidant capacity[biological antioxidant potential(BAP)].METHODS Females presenting with secondary amenorrhea over 4 mo and a follicle stimulating hormone level of>40 mIU/mL were categorized into the POI group.Females presenting with a normal menstrual cycle and a follicle stimulating hormone level of>10.2 mIU/mL were categorized into the IOF group.Healthy females without ovarian hypofunction were categorized into the control group.Among females aged<40 years who visited our hospital from January 2021 to June 2022,we recruited 11 patients into both POI and IOF groups.For the potential antioxidant capacity,the relative oxidative stress index(BAP/d-ROMs×100)was calculated,and the oxidative stress defense system was comprehensively evaluated.RESULTS d-ROMs were significantly higher in the POI and IOF groups than in the control group,(478.2±58.7 U.CARR,434.5±60.6 U.CARR,and 341.1±35.1 U.CARR,respectively)(U.CARR is equivalent to 0.08 mg/dL of hydrogen peroxide).However,no significant difference was found between the POI and IOF groups.Regarding BAP,no significant difference was found between the control,IOF,and POI groups(2078.5±157.4μmol/L,2116.2±240.2μmol/L,and 2029.0±186.4μmol/L,respectively).The oxidative stress index was significantly higher in the POI and IOF groups than in the control group(23.7±3.3,20.7±3.6,and 16.5±2.1,respectively).However,no significant difference was found between the POI and IOF groups.CONCLUSION High levels of oxidative stress suggest that evaluating the oxidative stress state may be a useful indicator for the early detection of POI. 展开更多
关键词 Premature ovarian insufficiency Oxidative stress Diacron-reactive oxygen metabolites test Biological antioxidant potential INFERTILITY BIOMARKER
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Retrospective analysis of discordant results between histology and other clinical diagnostic tests on helicobacter pylori infection
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作者 Xiaohua Qi Kevin Kuan +3 位作者 Tony El Jabbour Yungtai Lo Qiang Liu Yanan Fang 《World Journal of Gastrointestinal Endoscopy》 2024年第2期64-71,共8页
BACKGROUND A reliable test is essential for diagnosing Helicobacter pylori(H.pylori)infection,and crucial for managing H.pylori-related diseases.Serving as an excellent method for detecting H.pylori infection,histolog... BACKGROUND A reliable test is essential for diagnosing Helicobacter pylori(H.pylori)infection,and crucial for managing H.pylori-related diseases.Serving as an excellent method for detecting H.pylori infection,histologic examination is a test that clinicians heavily rely on,especially when complemented with immunohistochemistry(IHC).Additionally,other diagnostic tests for H.pylori,such as the rapid urease test(CLO test)and stool antigen test(SA),are also highly sensitive and specific.Typically,the results of histology and other tests align with each other.However,on rare occasions,discrepancy between histopathology and other H.pylori diagnostic tests occurs.AIM To investigate the discordance between histology and other H.pylori tests,the underlying causes,and the impact on clinical management.METHODS Pathology reports of gastric biopsies were retrieved spanning August 2013 and July 2018.Reports were included in the study only if there were other H.pylori tests within seven days of the biopsy.These additional tests include CLO test,SA,and H.pylori culture.Concordance between histopathology and other tests was determined based on the consistency of results.In instances where histology results were negative while other tests were positive,the slides were retrieved for re-assessment,and the clinical chart was reviewed.RESULTS Of 1396 pathology reports were identified,each accompanied by one additional H.pylori test.The concordance rates in detecting H.pylori infection between biopsy and other tests did not exhibit significant differences based on the number of biopsy fragments.117 discrepant cases were identified.Only 20 cases(9 with CLO test and 11 with SA)had negative biopsy but positive results in other tests.Four cases initially stained with Warthin-Starry turned out to be positive for H.pylori with subsequent IHC staining.Among the remaining 16 true discrepant cases,10 patients were on proton pump inhibitors before the biopsy and/or other tests.Most patients underwent treatment,except for two who were untreated,and two patients who were lost to follow-up.CONCLUSION There are rare discrepant cases with negative biopsy but positive in SA or CLO test.Various factors may contribute to this inconsistency.Most patients in such cases had undergone treatment. 展开更多
关键词 Helicobacter pylori DISCORDANCE Gastric biopsy HISTOLOGY Rapid urease test Stool antigen test Helicobacter pylori culture
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Assessing cutter-rock interaction during TBM tunnelling in granite:Large-scale standing rotary cutting tests and 3D DEM simulations
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作者 Xin Huang Miaoyuan Tang +4 位作者 Shuaifeng Wang Yixin Zhai Qianwei Zhuang Chi Zhang Qinghua Lei 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3595-3615,共21页
The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standi... The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standing rotary cutting tests on granite in conjunction with high-fidelity numerical simulations based on a particle-type discrete element method(DEM)to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses.The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters.More specifically,the normal and rolling forces exhibit a positive correlation with penetration but are slightly influenced by the cutting radius.In contrast,the side force decreases as the cutting radius increases.Additionally,the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases.The cutter's relative effectiveness in rock breaking is significantly impacted by the penetration but shows little dependency on the cutting radius.Consequently,an optimal penetration is identified,leading to a low boreability index and specific energy.A combined Hertz-Weibull function is developed to fit the cutter-rock contact stress distribution obtained in DEM simulations,whereby an improved CSM(Colorado School of Mines)model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model.The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/simulations.The findings from this work that advance our understanding of TBM cutter performance have important implications for improving the efficiency and reliability of TBM tunnelling in granite. 展开更多
关键词 Large-scale standing rotary cutting test Discrete element method(DEM)simulation Cutter-rock interaction Improved CSM(Colorado School of Mines) model Cutting force
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A thermal stress loading technique for large-sized hot dry rock mechanical tests
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作者 Huiling Ci Bing Bai +2 位作者 Hongwu Lei Yan Zou Jianfeng Liu 《Deep Underground Science and Engineering》 2024年第3期326-337,共12页
Testing of large-sized specimens is becoming increasingly important in deep underground rock mechanics and engineering.In traditional mechanical loading,stresses on large-sized specimens are achieved by large host fra... Testing of large-sized specimens is becoming increasingly important in deep underground rock mechanics and engineering.In traditional mechanical loading,stresses on large-sized specimens are achieved by large host frames and hydraulic pumps,which could lead to great investment.Low-cost testing machines clearly always have great appeal.In this study,a new approach is proposed using thermal expansion stress to load rock specimens,which may be particularly suitable for tests of deep hot dry rock with high temperatures.This is a different technical route from traditional mechanical loading through hydraulic pressure.For the rock mechanics test system of hot dry rock that already has an investment in heating systems,this technology may reduce the cost of the loading subsystem by fully utilizing the temperature changes.This paper presents the basic principle and a typical design of this technical solution.Preliminary feasibility analysis is then conducted based on numerical simulations.Although some technical details still need to be resolved,the feasibility of this loading approach has been preliminarily confirmed. 展开更多
关键词 deep rock engineering high-temperature and high-stress conditions hot dry rock large-sized model test thermal stress loading
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Behavior of transporting pipeline sections without and with hydrogen exposure based on full-scale tests
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作者 Nóra Nagy János Lukács 《China Welding》 CAS 2024年第3期14-24,共11页
Pipeline transport of hydrogen is one of today’s economic and environmental challenges.In order to find safe and reliable application of both existing gas and build new pipelines,it is essential to carry out tests on... Pipeline transport of hydrogen is one of today’s economic and environmental challenges.In order to find safe and reliable application of both existing gas and build new pipelines,it is essential to carry out tests on full-scale pipeline section,including the potentially more dangerous places than the main pipe,the girth welds.For the investigations,pipeline sections of P355NH steel with girth welds were prepared and exposed to pure hydrogen at twice the maximum allowable operating pressure for 41 days.Subsequently,full-scale burst tests were carried out and specimens were cut and prepared from the typical locations of the failed pipeline sections for mechanical,and macro-and microstructural investigations.The results obtained were evaluated and compared with data from previous full-scale tests on pipeline sections without hydrogen exposure.The results showed differences in the behavior of pipeline sections loaded in different ways,with different characteristics of the materials and the welded joints,both in the cases without hydrogen exposure and in the cases exposed to hydrogen. 展开更多
关键词 gas transporting pipeline full-scale pipeline test complex loading condition hydrogen exposure safety factor
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Comparison of Type I Error Rates of Siegel-Tukey and Savage Tests among Non-Parametric Tests
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作者 Sahib Ramazanov Hakan Çora 《Open Journal of Applied Sciences》 2024年第9期2393-2410,共18页
This study aimed to examine the performance of the Siegel-Tukey and Savage tests on data sets with heterogeneous variances. The analysis, considering Normal, Platykurtic, and Skewed distributions and a standard deviat... This study aimed to examine the performance of the Siegel-Tukey and Savage tests on data sets with heterogeneous variances. The analysis, considering Normal, Platykurtic, and Skewed distributions and a standard deviation ratio of 1, was conducted for both small and large sample sizes. For small sample sizes, two main categories were established: equal and different sample sizes. Analyses were performed using Monte Carlo simulations with 20,000 repetitions for each scenario, and the simulations were evaluated using SAS software. For small sample sizes, the I. type error rate of the Siegel-Tukey test generally ranged from 0.045 to 0.055, while the I. type error rate of the Savage test was observed to range from 0.016 to 0.041. Similar trends were observed for Platykurtic and Skewed distributions. In scenarios with different sample sizes, the Savage test generally exhibited lower I. type error rates. For large sample sizes, two main categories were established: equal and different sample sizes. For large sample sizes, the I. type error rate of the Siegel-Tukey test ranged from 0.047 to 0.052, while the I. type error rate of the Savage test ranged from 0.043 to 0.051. In cases of equal sample sizes, both tests generally had lower error rates, with the Savage test providing more consistent results for large sample sizes. In conclusion, it was determined that the Savage test provides lower I. type error rates for small sample sizes and that both tests have similar error rates for large sample sizes. These findings suggest that the Savage test could be a more reliable option when analyzing variance differences. 展开更多
关键词 Non-Parametric Test Siegel-Tukey Test Savage Test Monte Carlo Simulation Type I Error
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Study on Key Biological Indicators of Diabetes Based on Statistical Tests
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作者 Shuaibin Yang 《Journal of Clinical and Nursing Research》 2024年第7期267-273,共7页
Normality testing is a fundamental hypothesis test in the statistical analysis of key biological indicators of diabetes.If this assumption is violated,it may cause the test results to deviate from the true value,leadi... Normality testing is a fundamental hypothesis test in the statistical analysis of key biological indicators of diabetes.If this assumption is violated,it may cause the test results to deviate from the true value,leading to incorrect inferences and conclusions,and ultimately affecting the validity and accuracy of statistical inferences.Considering this,the study designs a unified analysis scheme for different data types based on parametric statistical test methods and non-parametric test methods.The data were grouped according to sample type and divided into discrete data and continuous data.To account for differences among subgroups,the conventional chi-squared test was used for discrete data.The normal distribution is the basis of many statistical methods;if the data does not follow a normal distribution,many statistical methods will fail or produce incorrect results.Therefore,before data analysis and modeling,the data were divided into normal and non-normal groups through normality testing.For normally distributed data,parametric statistical methods were used to judge the differences between groups.For non-normal data,non-parametric tests were employed to improve the accuracy of the analysis.Statistically significant indicators were retained according to the significance index P-value of the statistical test or corresponding statistics.These indicators were then combined with relevant medical background to further explore the etiology leading to the occurrence or transformation of diabetes status. 展开更多
关键词 Diabetes diagnosis Statistical test Nonparametric statistics Normality test
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Characterization of the key aroma compounds in four varieties of pomegranate juice by gas chromatography-mass spectrometry(GC-MS),gas chromatography-olfactometry(GC-O),odor activity value(OAV),aroma recombination,and omission tests 被引量:5
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作者 Cong Lu Yuyu Zhang +2 位作者 Ping Zhan Peng Wang Honglei Tian 《Food Science and Human Wellness》 SCIE CSCD 2023年第1期151-160,共10页
P omegranate(Punica granatum L.)has attracted considerable attention in world markets due to its valuable nutrients and highly appreciated sensory properties.The aroma profiles of 4 varieties of pomegranate juice,incl... P omegranate(Punica granatum L.)has attracted considerable attention in world markets due to its valuable nutrients and highly appreciated sensory properties.The aroma profiles of 4 varieties of pomegranate juice,including Dahongtian(DP),Jingpitian(JP),Luyudan(LP),and Tianhonngdan(TP),were investigated via gas chromatography-mass spectrometry(GC-MS)and gas chromatography-olfactometry(GC-O)analyses.A total of 43 volatile compounds were identified by using GC-MS.Among these compounds,16 were considered as potential aroma-active compounds as detected by GC-O.These compounds belonged to the classes of terpinenes,alcohols,and aldehydes.Eleven volatile compounds were defined as the main contributors to the overall aroma of pomegranate juice due to their high odor activity values(OAVs≥1).Aroma recombination and omission tests confirmed thatβ-myrcene,1-hexanol,and(Z)-3-hexen-1-ol were the key aroma compounds,and limonene,1-octen-3-ol,linalool,and hexanal were important aroma-active compounds in DP samples. 展开更多
关键词 Pomegranate juice Aroma-active compounds GC-MS GC-O Odor active value(OAV) Omission tests
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