BACKGROUND Helicobacter pylori(H.pylori),a globally prevalent pathogen,is exhibiting increasing rates of antimicrobial resistance.However,clinical implementation of pre-treatment susceptibility testing remains limited...BACKGROUND Helicobacter pylori(H.pylori),a globally prevalent pathogen,is exhibiting increasing rates of antimicrobial resistance.However,clinical implementation of pre-treatment susceptibility testing remains limited due to the organism’s fastidious growth requirements and prolonged culture time.AIM To propose a novel detection method utilizing antibiotic-supplemented media to inhibit susceptible strains,while resistant isolates were identified through urease-mediated hydrolysis of urea,inducing a phenol red color change for visual confirmation.METHODS Colombia agar was supplemented with urea,phenol red,and nickel chloride,and the final pH was adjusted to 7.35.Antibiotic-selective media were prepared by incorporating amoxicillin(0.5μg/mL),clarithromycin(2μg/mL),metronidazole(8μg/mL),or levofloxacin(2μg/mL)into separate batches.Gastric antral biopsies were homogenized and inoculated at 1.0×105 CFU onto the media,and then incubated under microaerobic conditions at 37°C for 28-36 hours.Resistance was determined based on a color change from yellow to pink,and the results were validated via broth microdilution according to Clinical and Laboratory Standards Institute guidelines.RESULTS After 28-36 hours of incubation,the drug-resistant H.pylori isolates induced a light red color change in the medium.Conversely,susceptible strains(H.pylori 26695 and G27)produced no visible color change.Compared with the conventional 11-day protocol,the novel method significantly reduced detection time.Among 201 clinical isolates,182 were successfully evaluated using the new method,resulting in a 90.5%detection rate.This was consistent with the 95.5%agreement rate observed when compared with microdilution-based susceptibility testing.The success rate of the novel approach was significantly higher than that of the comparative method(P<0.01).The accuracy of the new method was comparable to that of the dilution method.CONCLUSION The novel detection method can rapidly detect H.pylori drug resistance within 28-36 hours.With its operational simplicity and high diagnostic performance,it holds strong potential for clinical application in the management of H.pylori antimicrobial resistance.展开更多
In the research, changes of apple chemistry, and molecule, under stresses, are n terms of morphology, physiology, bio- illustrated and research and identifica- tion methods of apple resistance are explored involving ...In the research, changes of apple chemistry, and molecule, under stresses, are n terms of morphology, physiology, bio- illustrated and research and identifica- tion methods of apple resistance are explored involving drought-resistance, flood-re- sistance, salt-stress resistance, cold-hardiness and heat-resistance. In addition prospects of apple resistance research are proposed, as well.展开更多
H pylori is etiologically associated with gastritis, gas-tric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of ...H pylori is etiologically associated with gastritis, gas-tric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of related diseases with the use of more accurate diagnostic molecular tests. Indeed some of the tests cannot give the evidence of current infection; H pylori can be detected by noninvasive and invasive methods, the latter requiring an endoscopy. Eradication failure is a big problem in H pylori infection. Recently, clarithromycin resistance in H pylori strains is increasing and eradicati-on therapy of this bacterium is becoming more difficult. Molecular methods have frequently been applied besides phenotypic methods for susceptibility testing to detect clarithromycin resistance due to mutations in the 2143 and 2144 positions of 23S rRNA gene. Fluorescence in situ hybridization (FISH) method on paraffin embedded tissue is a rapid, accurate and cost-effective method for the detection of H pylori infection and to determine clarithromycin resistance within three hours according to the gold standards as a non-culture method. This method can also be applied to fresh biopsy samples and the isolated colonies from a culture of H pylori, detecting both the culturable bacillary forms and the coccoid forms of H pylori, besides the paraffin embedded tissue secti-ons. This technique is helpful for determining the bac-terial density and the results of treatment where clarith-romycin has been widely used in populations to increase the efficacy of the treatment and to clarify the treatment failure in vitro.展开更多
The hull form optimization concerns one of the most important applications of wave-making resistance theories.In recent years,scholars can determine the hull form by using the optimization method based on the computat...The hull form optimization concerns one of the most important applications of wave-making resistance theories.In recent years,scholars can determine the hull form by using the optimization method based on the computational fluid dynamics(CFD)and other mathematical techniques.In this paper,the hull form optimization method based on the Rankine source method and nonlinear programming(NLP)is discussed;in the optimization process,a hull form modification function is introduced to represent an improved hull surface and to generate a new smooth hull surface by changing its frame lines and bow stem profiles under the prescribed design constraints. Numerical example is given for a practical container hull form.Finally,shape optimization of bow bulls is shown for non-protruding and protruding bow bulls.This study presents a simplified and practical design method to the select frame lines of bow bulls.展开更多
The high boron alloy surfacing layer was easily cracked due to its insufficient toughness by using hybrid powder/ wire overlaying method. In order to explore the cracked mechanism, the microstructures and the wear res...The high boron alloy surfacing layer was easily cracked due to its insufficient toughness by using hybrid powder/ wire overlaying method. In order to explore the cracked mechanism, the microstructures and the wear resistance of the samples with different boron contents were studied. Further, phases analysis, microhardness, macrohardness and wear test were also carried out. The boron content depended microstructures were observed. The precipitation of the Fe2B, Fe3 （ C, B）, Fe23 （C, B）6 were increased with the increase of boron content. It was found that the wear resistance was independent of the macrohardness as the macrohardness increased firstly and then remained steady at -62 HRC. However, the wear resistance was depended on the boron contents, and which increased with the increase of the boron contents. The abrasive loss mechanism changed from plastic deformation removal to fracture removal.展开更多
In this paper, a panel method based on three dimensional potential flow theory is used to study the problem of wave added resistance. The time-domain motion response of Wigely III ship in head waves is calculated by A...In this paper, a panel method based on three dimensional potential flow theory is used to study the problem of wave added resistance. The time-domain motion response of Wigely III ship in head waves is calculated by AQWA, and then the wave added resistance of ship is obtained by near-field pressure integration method. By comparing the calculated results with the experimental data in literature, it is shown that the variation trend and peak value are in good agreement, and the accuracy and efficiency meet the research requirements. Based on the above mentioned method, the wave added resistance of a deep-V hybrid monohull in head waves is studied. The motions and wave added resistances of the deep-V hybrid monohull and the deep-V original ship advancing in head waves with various forward speed and wave frequencies are calculated and analyzed. The results show that the longitudinal motion response of the deep-V hybrid monohull is effectively suppressed and the wave added resistance is obviously reduced, the new type of ship has good engineering application prospects. The present method provides an approach of satisfactory accuracy and efficiency to predict wave added resistance of ships voyaging in waves.展开更多
Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some dis...Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some disadvantages and the evaluated results are only simple figures and always rely on the subjective experience of the operator. A new electrochemical method for evaluating the RCD of coatings, that is, the potentiostatic evaluation method （PEM）, was developed and studied. During potentiostatic anodic polarization testing, the changes of stable polarization current of specimens before and after cathodic disbonding （CD） were measured, and the degree of cathodic disbondment of the coating was quantitatively evaluated, among which the equivalent cathodic disbonded distance AD was suggested as a parameter for evaluating the RCD. A series of testing parameters of the PEM were determined in these experiments.展开更多
Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equ...Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equivalent circuits. Therefore, the current interruption method is explored to measure the value of RΩ in direct methanol fuel cells (DMFC) at different temperatures and current densities. It is found that RΩ decreases as temperature increase, and decreases initially and then increases as current density increases. These results are consistent with those measured by the EIS technique. In most cases, the ohmic resistances with current interruption (R iR ) are larger than those with EIS (R EIS ), but the difference is small, in the range from –0.848% to 5.337%. The errors of R iR at high current densities are less than those of R EIS . Our results show that the R iR data are reliable and easy to obtain in the measurement of ohmic resistance in DMFC.展开更多
The reliability of post grouting pile axial resistance was studied by proposing a design method for its probabilistic limit state,which is represented by the partial coefficients of load,end,and side resistance.The hy...The reliability of post grouting pile axial resistance was studied by proposing a design method for its probabilistic limit state,which is represented by the partial coefficients of load,end,and side resistance.The hyperbolic,modified hyperbolic,and polynomial models were employed to predict the ultimate bearing capacity of test piles that were not loaded to damage in field tests.The results were used for the calculation and calibration of the reliability index.The reliability of the probabilistic limit state design method was verified by an engineering case.The results show that the prediction results obtained from the modified hyperbolic model are closest to those obtained through the static load test.The proposed corresponding values of total,side,and end resistance partial coefficients are 1.84,1.66,and 2.73 when the dead and live load partial coefficients are taken as 1.1 and 1.4,respectively.Meanwhile,the corresponding partial coefficients of total,side,and end resistance are 1.70,1.56,and 2.34 when the dead and live load partial coefficients are taken as 1.2 and 1.4,respectively.展开更多
The cracking behavior of lightweight aggregate concrete(LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship betw...The cracking behavior of lightweight aggregate concrete(LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete(NWAC). A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt(t) and the evaluation index Acr(t) were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr(t) is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr(t) is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.展开更多
This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of con...This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of conventional diagnostic method. Typical GIS conductor poles are chosen. Based on FEA and lab tests, the effect of different forms of current and contact condition, relationship between the temperature of contact and the loop resistance is researched. In full- scale testing under realistic operating conditions on the new 220 kV GIS using prototype instrumentation a very good sensitivity in an early stage was obtained.展开更多
This study proposes a deep learning-based approach for shaft resistance evaluation of cast-in-site piles on reclaimed ground,independent of theoretical hypotheses and engineering experience.A series of field tests was...This study proposes a deep learning-based approach for shaft resistance evaluation of cast-in-site piles on reclaimed ground,independent of theoretical hypotheses and engineering experience.A series of field tests was first performed to investigate the characteristics of the shaft resistance of cast-in-site piles on reclaimed ground.Then,an intelligent approach based on the long short term memory deep-learning technique was proposed to calculate the shaft resistance of the cast-in-site pile.The proposed method allows accurate estimation of the shaft resistance of cast-in-site piles,not only under the ultimate load but also under the working load.Comparisons with empirical methods confirmed the effectiveness of the proposed method for the shaft resistance estimation of cast-in-site piles on reclaimed ground in offshore areas.展开更多
When the ship is sailing at sea,wave added resistance has great influence on the rapidity and economy of the ship.With the increasing pressure of energy and environmental protection,IMO has proposed the EEDI formula o...When the ship is sailing at sea,wave added resistance has great influence on the rapidity and economy of the ship.With the increasing pressure of energy and environmental protection,IMO has proposed the EEDI formula of the newly built ships,which restricts the energy consumption standard of civil ships more strictly.Therefore,a panel method based on three dimensional potential flow theory is proposed to study the problem of wave added resistance in this paper.Firstly,the method solves the motion responses of the ship in the time domain,and then calculates the wave added resistance of the ship by near-field pressure integration method.The wave added resistance of S175 container ship in head and oblique waves are calculated and compared with the experimental data,and the accuracy of the proposed method are verified.At last,the influence of Froude number and wave direction angle on wave added resistance is studied.The proposed method provides an approach of satisfactory accuracy and efficiency for the development of high-performance new ship forms,optimization of ship hull lines,comprehensive performance evaluation of ships and practical navigation guidance.展开更多
Heating the oil shale by current underground to accomplish in-situ transformation process, is a viable direction. The electrical properties of oil shale under different temperatures, especially the resistance, become ...Heating the oil shale by current underground to accomplish in-situ transformation process, is a viable direction. The electrical properties of oil shale under different temperatures, especially the resistance, become important. Charging oil shale underground to heat oil shale till kerogen's decomposition temperature, then crude oil and other gases can be generated. The resistance of the oil shale samples was measured by Direct Current (DC) quadripole method to find out the variation rules of resistance value. In the experiments, oil shale presented its semiconductor property. When heated till 350℃-450℃, its resistance changed greatly, optional for heating and cracking. The porosity, oil content, media and composition affected the resistance largely.展开更多
[Objectives]To identify the drought resistance of main wheat varieties in Shandong Province and screen suitable cultivars for dryland cultivation.[Methods]Employing eight varieties including Jimai 60 as test materials...[Objectives]To identify the drought resistance of main wheat varieties in Shandong Province and screen suitable cultivars for dryland cultivation.[Methods]Employing eight varieties including Jimai 60 as test materials,this study simulated drought stress using 20%PEG-6000 and measured changes in germination-stage indicators.A comprehensive evaluation was conducted using the membership function method,incorporating relative coleoptile length,relative germ length,relative radicle length,relative germination rate,relative germination potential,and stress germination index.[Results]Drought stress not only reduced wheat seed germination rate but also inhibited the growth of the germ,coleoptile,and radicle.The D values of the eight varieties were ranked as follows:Jimai 60>Linmai 9>Yannong 999>Shannong 30>Shannong 28>Luyuan 502>Yannong 1212>Jimai 22.Based on D values,the eight dominant wheat varieties were classified into three categories:highly drought-resistant varieties(Linmai 9 and Jimai 60),moderately drought-resistant varieties(Yannong 999 and Shannong 30),and sensitive varieties(the others).Linmai 9 and Jimai 60 are recommended as suitable wheat varieties for dryland cultivation in Shandong Province.[Conclusions]Drought stress induced by 20%PEG-6000 reduced germination rate,germination potential,and germination index of wheat varieties while inhibiting the growth of coleoptiles and radicles.These indicators can provide a preliminary assessment of drought resistance in wheat cultivars.However,since filter paper was selected as the growth medium,root length measurement errors were introduced during root washing,leading to variations in final experimental results.Futuer studies could attempt using sterilized sand as an alternative growth medium.展开更多
Mgo-Cao refractories are widely used in the iron and steel metalurgy industry due to their advantages of purifying molten steel,high refractoriness,good thermal shock resistance,and excellent corrosion resistance to b...Mgo-Cao refractories are widely used in the iron and steel metalurgy industry due to their advantages of purifying molten steel,high refractoriness,good thermal shock resistance,and excellent corrosion resistance to basic slags.However,hydration occurs during the manufacturing,storage,and transportation of refractories,which severely limits their application.Mgo-CaO clinker is the main raw material for Mgo-Cao refractories,and its hydration resistance determines the development of the latter case.Herein,the Mgo-Cao clinker was modified using myristic acid as the modifying agent by the liquid-phase deposition method.The effects of the particle size of the raw materials,concentration of myristic acid,treatment temperature and time on the phase composition and hydration resistance of the modified Mgo-Cao clinkers were investigated in detail.The results show that the samples with an agent concentration of 0.25 mol L^(-1) and treated at 25℃ for 1 h exhibit the optimal hydration resistance properties,namely a low hydration mass gain rate(0.23%)and a large water contact angle(152.9).展开更多
A parallel finite element scheme for 3D resistivity method forward modeling is introduced in this article.The domain decomposition algorithm,along with a message passing interface,is used to implement parallelism.The ...A parallel finite element scheme for 3D resistivity method forward modeling is introduced in this article.The domain decomposition algorithm,along with a message passing interface,is used to implement parallelism.The computational domain is divided into subdomains,and mesh partitioning is combined with load balancing.Unstructured meshes and local mesh refinement strategies are used to realize high precision for complex topography models.Furthermore,an improved linear solver for multi-electrode resistivity method modeling is adopted.Recycling preconditioned conjugate gradient,which is a linear solver,is based on the similarity of linear systems between point sources.The multiple right-hand-side linear systems corresponding to different point source positions are constructed,and the accelerated convergence is obtained through recycling subspace using the linear solver.The computational accuracy and efficiency of the forward scheme for complex topography models are verified using the numerical test results.展开更多
Ground anchor drilling is a promising technology for investigating the mechanical properties and environmental variability of lunar regolith in low-gravity environments,with minimal demands for reactive cutting.This s...Ground anchor drilling is a promising technology for investigating the mechanical properties and environmental variability of lunar regolith in low-gravity environments,with minimal demands for reactive cutting.This study explores the interaction behavior during ground anchor drilling of lunar regolith by employing a coupled approach that integrates the Material Point Method(MPM)and the ContinuouseDiscontinuous Element Method(CDEM),considering the interactions among numerous particles and blocks.The numerical parameters are calibrated based on experimental penetration resistance data of lunar regolith simulant.The numerical approach effectively captures key mechanical properties of the simulant,such as particle flow and scattering patterns,anchor penetration effects,and disturbance-related ultimate bearing characteristics.Additionally,this study examines the influence of inter-particle friction and compactness on penetration resistance.By combining the Golden Section Search Method(GSSM)with ground anchor drilling simulations,an inverse analysis model for penetration resistance is developed,allowing for the determination of mechanical parameters of the lunar regolith simulant.The feasibility of this parameter inversion method is verified,providing valuable insights for engineering applications in lunar exploration and construction.展开更多
Panel methods for the calculation of wavemaking resistance result in a linear equation system for the unknown singularities.The coefficient matrix is full but not well conditioned.In this paper an incomplete LU decomp...Panel methods for the calculation of wavemaking resistance result in a linear equation system for the unknown singularities.The coefficient matrix is full but not well conditioned.In this paper an incomplete LU decomposition (ILU) method and a combined multigrid ILU method are used to solve the linear system.Systematic computations using the ILU method have shown that the CPU time can be reduced to 30% to 40% of that using an incomplete Gaussian elimination method. In the proposed multigrid ILU method an averaged restriction and a piecewise constant prolongation are used.The construction of the coefficient matrix at coarse levels is based on geometrical considerations.It turns out that the condition of the relative consistency is fulfilled.Comparison computations have shown that nearly the same results were obtained.However,due to additional CPU time needed for the execution of the matrix vector products in the restriction and the prolongation proceses of the multigrid method,a further reduction of the total CPU time could not be reailized.展开更多
In the leakage detection of reservoir dam bodies,traditional geophysical methods can only achieve one-time detection.Meanwhile,due to the non-uniqueness of geophysicalin version,how to improve the fidelity of geophysi...In the leakage detection of reservoir dam bodies,traditional geophysical methods can only achieve one-time detection.Meanwhile,due to the non-uniqueness of geophysicalin version,how to improve the fidelity of geophysical detection inversion profiles has become a key challenge in the industry.This study aims to construct a long-term real-time monitoring system using the time-lapse resistivity method,reveal the spatiotemporal evolution law of dam leakage,and provide technical support for accurate treatment.By integrating the Internet of Things(IoT),5G technology,and AI technology,real-time data acquisition,real-time transmission,and automatic inversionare realized.Through dynamic imaging analysis of the electrical anomaly characteristics of the leakage area and comparison between corresponding rainfall events,the leakage range and resistivity changes,the reliability and efficiency of dam leakagedete ction are significantly improved.This achieves long-termdynamic monitoring of dam leakage and provides a new perspective for the safe operation and maintenance of reservoirs.展开更多
基金Supported by the Guangxi Science and Technology Major Projects,No.AA23073012the National Natural Science Foundation of China,No.32360035 and No.32060018。
文摘BACKGROUND Helicobacter pylori(H.pylori),a globally prevalent pathogen,is exhibiting increasing rates of antimicrobial resistance.However,clinical implementation of pre-treatment susceptibility testing remains limited due to the organism’s fastidious growth requirements and prolonged culture time.AIM To propose a novel detection method utilizing antibiotic-supplemented media to inhibit susceptible strains,while resistant isolates were identified through urease-mediated hydrolysis of urea,inducing a phenol red color change for visual confirmation.METHODS Colombia agar was supplemented with urea,phenol red,and nickel chloride,and the final pH was adjusted to 7.35.Antibiotic-selective media were prepared by incorporating amoxicillin(0.5μg/mL),clarithromycin(2μg/mL),metronidazole(8μg/mL),or levofloxacin(2μg/mL)into separate batches.Gastric antral biopsies were homogenized and inoculated at 1.0×105 CFU onto the media,and then incubated under microaerobic conditions at 37°C for 28-36 hours.Resistance was determined based on a color change from yellow to pink,and the results were validated via broth microdilution according to Clinical and Laboratory Standards Institute guidelines.RESULTS After 28-36 hours of incubation,the drug-resistant H.pylori isolates induced a light red color change in the medium.Conversely,susceptible strains(H.pylori 26695 and G27)produced no visible color change.Compared with the conventional 11-day protocol,the novel method significantly reduced detection time.Among 201 clinical isolates,182 were successfully evaluated using the new method,resulting in a 90.5%detection rate.This was consistent with the 95.5%agreement rate observed when compared with microdilution-based susceptibility testing.The success rate of the novel approach was significantly higher than that of the comparative method(P<0.01).The accuracy of the new method was comparable to that of the dilution method.CONCLUSION The novel detection method can rapidly detect H.pylori drug resistance within 28-36 hours.With its operational simplicity and high diagnostic performance,it holds strong potential for clinical application in the management of H.pylori antimicrobial resistance.
基金Supported by Shandong Provincial Natural Science Foundation in China(ZR2011CM034)~~
文摘In the research, changes of apple chemistry, and molecule, under stresses, are n terms of morphology, physiology, bio- illustrated and research and identifica- tion methods of apple resistance are explored involving drought-resistance, flood-re- sistance, salt-stress resistance, cold-hardiness and heat-resistance. In addition prospects of apple resistance research are proposed, as well.
文摘H pylori is etiologically associated with gastritis, gas-tric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of related diseases with the use of more accurate diagnostic molecular tests. Indeed some of the tests cannot give the evidence of current infection; H pylori can be detected by noninvasive and invasive methods, the latter requiring an endoscopy. Eradication failure is a big problem in H pylori infection. Recently, clarithromycin resistance in H pylori strains is increasing and eradicati-on therapy of this bacterium is becoming more difficult. Molecular methods have frequently been applied besides phenotypic methods for susceptibility testing to detect clarithromycin resistance due to mutations in the 2143 and 2144 positions of 23S rRNA gene. Fluorescence in situ hybridization (FISH) method on paraffin embedded tissue is a rapid, accurate and cost-effective method for the detection of H pylori infection and to determine clarithromycin resistance within three hours according to the gold standards as a non-culture method. This method can also be applied to fresh biopsy samples and the isolated colonies from a culture of H pylori, detecting both the culturable bacillary forms and the coccoid forms of H pylori, besides the paraffin embedded tissue secti-ons. This technique is helpful for determining the bac-terial density and the results of treatment where clarith-romycin has been widely used in populations to increase the efficacy of the treatment and to clarify the treatment failure in vitro.
基金the National Natural Science Foundation of China(No.51009087)
文摘The hull form optimization concerns one of the most important applications of wave-making resistance theories.In recent years,scholars can determine the hull form by using the optimization method based on the computational fluid dynamics(CFD)and other mathematical techniques.In this paper,the hull form optimization method based on the Rankine source method and nonlinear programming(NLP)is discussed;in the optimization process,a hull form modification function is introduced to represent an improved hull surface and to generate a new smooth hull surface by changing its frame lines and bow stem profiles under the prescribed design constraints. Numerical example is given for a practical container hull form.Finally,shape optimization of bow bulls is shown for non-protruding and protruding bow bulls.This study presents a simplified and practical design method to the select frame lines of bow bulls.
基金supported by the Heilongjiang Province Natural Science Foundation(No.ZD201008)Jiamusi University Scientific Research Project(22Zb201518)State Key Laboratory of Advanced Welding Production Technology Project(AWJ-M13-04)
文摘The high boron alloy surfacing layer was easily cracked due to its insufficient toughness by using hybrid powder/ wire overlaying method. In order to explore the cracked mechanism, the microstructures and the wear resistance of the samples with different boron contents were studied. Further, phases analysis, microhardness, macrohardness and wear test were also carried out. The boron content depended microstructures were observed. The precipitation of the Fe2B, Fe3 （ C, B）, Fe23 （C, B）6 were increased with the increase of boron content. It was found that the wear resistance was independent of the macrohardness as the macrohardness increased firstly and then remained steady at -62 HRC. However, the wear resistance was depended on the boron contents, and which increased with the increase of the boron contents. The abrasive loss mechanism changed from plastic deformation removal to fracture removal.
基金financial support from the National Natural Science Foundation of China (Nos.51709246, U1806229, 51809244, and 51609220)the Fundamental Research Funds for the Central Universities (No.201713031)。
文摘In this paper, a panel method based on three dimensional potential flow theory is used to study the problem of wave added resistance. The time-domain motion response of Wigely III ship in head waves is calculated by AQWA, and then the wave added resistance of ship is obtained by near-field pressure integration method. By comparing the calculated results with the experimental data in literature, it is shown that the variation trend and peak value are in good agreement, and the accuracy and efficiency meet the research requirements. Based on the above mentioned method, the wave added resistance of a deep-V hybrid monohull in head waves is studied. The motions and wave added resistances of the deep-V hybrid monohull and the deep-V original ship advancing in head waves with various forward speed and wave frequencies are calculated and analyzed. The results show that the longitudinal motion response of the deep-V hybrid monohull is effectively suppressed and the wave added resistance is obviously reduced, the new type of ship has good engineering application prospects. The present method provides an approach of satisfactory accuracy and efficiency to predict wave added resistance of ships voyaging in waves.
基金This work is financially supported by the National Natural Science Foundation of China (No.2992021).
文摘Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some disadvantages and the evaluated results are only simple figures and always rely on the subjective experience of the operator. A new electrochemical method for evaluating the RCD of coatings, that is, the potentiostatic evaluation method （PEM）, was developed and studied. During potentiostatic anodic polarization testing, the changes of stable polarization current of specimens before and after cathodic disbonding （CD） were measured, and the degree of cathodic disbondment of the coating was quantitatively evaluated, among which the equivalent cathodic disbonded distance AD was suggested as a parameter for evaluating the RCD. A series of testing parameters of the PEM were determined in these experiments.
基金Supported by the National High Technology Research and Development Program of China （2007AA05Z150） the National Natural Science Foundation of China （50911140287 50973055）
文摘Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equivalent circuits. Therefore, the current interruption method is explored to measure the value of RΩ in direct methanol fuel cells (DMFC) at different temperatures and current densities. It is found that RΩ decreases as temperature increase, and decreases initially and then increases as current density increases. These results are consistent with those measured by the EIS technique. In most cases, the ohmic resistances with current interruption (R iR ) are larger than those with EIS (R EIS ), but the difference is small, in the range from –0.848% to 5.337%. The errors of R iR at high current densities are less than those of R EIS . Our results show that the R iR data are reliable and easy to obtain in the measurement of ohmic resistance in DMFC.
基金The National Natural Science Foundation of China(No.51878160,52008100,52078128).
文摘The reliability of post grouting pile axial resistance was studied by proposing a design method for its probabilistic limit state,which is represented by the partial coefficients of load,end,and side resistance.The hyperbolic,modified hyperbolic,and polynomial models were employed to predict the ultimate bearing capacity of test piles that were not loaded to damage in field tests.The results were used for the calculation and calibration of the reliability index.The reliability of the probabilistic limit state design method was verified by an engineering case.The results show that the prediction results obtained from the modified hyperbolic model are closest to those obtained through the static load test.The proposed corresponding values of total,side,and end resistance partial coefficients are 1.84,1.66,and 2.73 when the dead and live load partial coefficients are taken as 1.1 and 1.4,respectively.Meanwhile,the corresponding partial coefficients of total,side,and end resistance are 1.70,1.56,and 2.34 when the dead and live load partial coefficients are taken as 1.2 and 1.4,respectively.
基金Project(51078090)supported by the National Natural Science Foundation of China
文摘The cracking behavior of lightweight aggregate concrete(LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete(NWAC). A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt(t) and the evaluation index Acr(t) were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr(t) is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr(t) is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.
文摘This paper studies the method for measuring the loop resistance of GIS conductor pole based on the super capacitor producing impulse current up to several thousand amperes. This method overcomes the limitations of conventional diagnostic method. Typical GIS conductor poles are chosen. Based on FEA and lab tests, the effect of different forms of current and contact condition, relationship between the temperature of contact and the loop resistance is researched. In full- scale testing under realistic operating conditions on the new 220 kV GIS using prototype instrumentation a very good sensitivity in an early stage was obtained.
基金the Research Funding of Shantou University for New Faculty Member(No.NTF19024-2019)the National Nature Science Foundation of China(No.41372283)。
文摘This study proposes a deep learning-based approach for shaft resistance evaluation of cast-in-site piles on reclaimed ground,independent of theoretical hypotheses and engineering experience.A series of field tests was first performed to investigate the characteristics of the shaft resistance of cast-in-site piles on reclaimed ground.Then,an intelligent approach based on the long short term memory deep-learning technique was proposed to calculate the shaft resistance of the cast-in-site pile.The proposed method allows accurate estimation of the shaft resistance of cast-in-site piles,not only under the ultimate load but also under the working load.Comparisons with empirical methods confirmed the effectiveness of the proposed method for the shaft resistance estimation of cast-in-site piles on reclaimed ground in offshore areas.
基金the National Natural Science Foundation of China(Nos.51709246,52171280,51609220,U1806229)。
文摘When the ship is sailing at sea,wave added resistance has great influence on the rapidity and economy of the ship.With the increasing pressure of energy and environmental protection,IMO has proposed the EEDI formula of the newly built ships,which restricts the energy consumption standard of civil ships more strictly.Therefore,a panel method based on three dimensional potential flow theory is proposed to study the problem of wave added resistance in this paper.Firstly,the method solves the motion responses of the ship in the time domain,and then calculates the wave added resistance of the ship by near-field pressure integration method.The wave added resistance of S175 container ship in head and oblique waves are calculated and compared with the experimental data,and the accuracy of the proposed method are verified.At last,the influence of Froude number and wave direction angle on wave added resistance is studied.The proposed method provides an approach of satisfactory accuracy and efficiency for the development of high-performance new ship forms,optimization of ship hull lines,comprehensive performance evaluation of ships and practical navigation guidance.
文摘Heating the oil shale by current underground to accomplish in-situ transformation process, is a viable direction. The electrical properties of oil shale under different temperatures, especially the resistance, become important. Charging oil shale underground to heat oil shale till kerogen's decomposition temperature, then crude oil and other gases can be generated. The resistance of the oil shale samples was measured by Direct Current (DC) quadripole method to find out the variation rules of resistance value. In the experiments, oil shale presented its semiconductor property. When heated till 350℃-450℃, its resistance changed greatly, optional for heating and cracking. The porosity, oil content, media and composition affected the resistance largely.
基金Supported by National Wheat Industry Technology System"Linyi Integrated Experimental Station"(CARS-03-66)Shandong Provincial Modern Agricultural Industry Technology System"Linyi Integrated Experimental Station"(SDATT-01-18).
文摘[Objectives]To identify the drought resistance of main wheat varieties in Shandong Province and screen suitable cultivars for dryland cultivation.[Methods]Employing eight varieties including Jimai 60 as test materials,this study simulated drought stress using 20%PEG-6000 and measured changes in germination-stage indicators.A comprehensive evaluation was conducted using the membership function method,incorporating relative coleoptile length,relative germ length,relative radicle length,relative germination rate,relative germination potential,and stress germination index.[Results]Drought stress not only reduced wheat seed germination rate but also inhibited the growth of the germ,coleoptile,and radicle.The D values of the eight varieties were ranked as follows:Jimai 60>Linmai 9>Yannong 999>Shannong 30>Shannong 28>Luyuan 502>Yannong 1212>Jimai 22.Based on D values,the eight dominant wheat varieties were classified into three categories:highly drought-resistant varieties(Linmai 9 and Jimai 60),moderately drought-resistant varieties(Yannong 999 and Shannong 30),and sensitive varieties(the others).Linmai 9 and Jimai 60 are recommended as suitable wheat varieties for dryland cultivation in Shandong Province.[Conclusions]Drought stress induced by 20%PEG-6000 reduced germination rate,germination potential,and germination index of wheat varieties while inhibiting the growth of coleoptiles and radicles.These indicators can provide a preliminary assessment of drought resistance in wheat cultivars.However,since filter paper was selected as the growth medium,root length measurement errors were introduced during root washing,leading to variations in final experimental results.Futuer studies could attempt using sterilized sand as an alternative growth medium.
基金National Natural Science Foundation of China(Grants 52202025 and U23A20559)Natural Science Foundation of Hubei Province(Grant 2022CFB629)+1 种基金"The 14^(th)Five-Year Plan"Hubei Provincial Advantaged Characteristic Disciplines(Groups)Project of Wuhan University of Science and Technology(2023A0307).
文摘Mgo-Cao refractories are widely used in the iron and steel metalurgy industry due to their advantages of purifying molten steel,high refractoriness,good thermal shock resistance,and excellent corrosion resistance to basic slags.However,hydration occurs during the manufacturing,storage,and transportation of refractories,which severely limits their application.Mgo-CaO clinker is the main raw material for Mgo-Cao refractories,and its hydration resistance determines the development of the latter case.Herein,the Mgo-Cao clinker was modified using myristic acid as the modifying agent by the liquid-phase deposition method.The effects of the particle size of the raw materials,concentration of myristic acid,treatment temperature and time on the phase composition and hydration resistance of the modified Mgo-Cao clinkers were investigated in detail.The results show that the samples with an agent concentration of 0.25 mol L^(-1) and treated at 25℃ for 1 h exhibit the optimal hydration resistance properties,namely a low hydration mass gain rate(0.23%)and a large water contact angle(152.9).
基金supported by the National Natural Science Foundation of China(No:42274182)Guangxi Natural Science Foundation(No:2020 GXNSFAA297079)。
文摘A parallel finite element scheme for 3D resistivity method forward modeling is introduced in this article.The domain decomposition algorithm,along with a message passing interface,is used to implement parallelism.The computational domain is divided into subdomains,and mesh partitioning is combined with load balancing.Unstructured meshes and local mesh refinement strategies are used to realize high precision for complex topography models.Furthermore,an improved linear solver for multi-electrode resistivity method modeling is adopted.Recycling preconditioned conjugate gradient,which is a linear solver,is based on the similarity of linear systems between point sources.The multiple right-hand-side linear systems corresponding to different point source positions are constructed,and the accelerated convergence is obtained through recycling subspace using the linear solver.The computational accuracy and efficiency of the forward scheme for complex topography models are verified using the numerical test results.
基金financial support from the National Natural Science Foundation of China(Grant Nos.52178324,12102059,and 12472207).
文摘Ground anchor drilling is a promising technology for investigating the mechanical properties and environmental variability of lunar regolith in low-gravity environments,with minimal demands for reactive cutting.This study explores the interaction behavior during ground anchor drilling of lunar regolith by employing a coupled approach that integrates the Material Point Method(MPM)and the ContinuouseDiscontinuous Element Method(CDEM),considering the interactions among numerous particles and blocks.The numerical parameters are calibrated based on experimental penetration resistance data of lunar regolith simulant.The numerical approach effectively captures key mechanical properties of the simulant,such as particle flow and scattering patterns,anchor penetration effects,and disturbance-related ultimate bearing characteristics.Additionally,this study examines the influence of inter-particle friction and compactness on penetration resistance.By combining the Golden Section Search Method(GSSM)with ground anchor drilling simulations,an inverse analysis model for penetration resistance is developed,allowing for the determination of mechanical parameters of the lunar regolith simulant.The feasibility of this parameter inversion method is verified,providing valuable insights for engineering applications in lunar exploration and construction.
文摘Panel methods for the calculation of wavemaking resistance result in a linear equation system for the unknown singularities.The coefficient matrix is full but not well conditioned.In this paper an incomplete LU decomposition (ILU) method and a combined multigrid ILU method are used to solve the linear system.Systematic computations using the ILU method have shown that the CPU time can be reduced to 30% to 40% of that using an incomplete Gaussian elimination method. In the proposed multigrid ILU method an averaged restriction and a piecewise constant prolongation are used.The construction of the coefficient matrix at coarse levels is based on geometrical considerations.It turns out that the condition of the relative consistency is fulfilled.Comparison computations have shown that nearly the same results were obtained.However,due to additional CPU time needed for the execution of the matrix vector products in the restriction and the prolongation proceses of the multigrid method,a further reduction of the total CPU time could not be reailized.
文摘In the leakage detection of reservoir dam bodies,traditional geophysical methods can only achieve one-time detection.Meanwhile,due to the non-uniqueness of geophysicalin version,how to improve the fidelity of geophysical detection inversion profiles has become a key challenge in the industry.This study aims to construct a long-term real-time monitoring system using the time-lapse resistivity method,reveal the spatiotemporal evolution law of dam leakage,and provide technical support for accurate treatment.By integrating the Internet of Things(IoT),5G technology,and AI technology,real-time data acquisition,real-time transmission,and automatic inversionare realized.Through dynamic imaging analysis of the electrical anomaly characteristics of the leakage area and comparison between corresponding rainfall events,the leakage range and resistivity changes,the reliability and efficiency of dam leakagedete ction are significantly improved.This achieves long-termdynamic monitoring of dam leakage and provides a new perspective for the safe operation and maintenance of reservoirs.
