A cased well model consists of a coaxial tank and casing,which houses coaxially installed transmitting and receiving coils.The transmitting coil is excited by the current produced by the transmitting circuit,and trans...A cased well model consists of a coaxial tank and casing,which houses coaxially installed transmitting and receiving coils.The transmitting coil is excited by the current produced by the transmitting circuit,and transient electromagnetic responses occur in the casing,including direct coupling and casing responses.As the range between the transmitting and receiving coils increases,direct coupling responses decay rapidly,are less than the casing response at 0.3 m,and disappear at 0.7 m.By contrast,a casing response increases rapidly and then declines slowly after reaching a peak and changes little within a specifi c range.The peak decreases slowly with range.The continuous addition of water to the tank causes slight changes in transient electromagnetic responses,so the diff erence which are subtracted from the response without water is used.Moreover,the diff erences at the time of rapid increase in response and the time of rapid decrease in response are large,forming a peak and a trough.Given that the conductivity of water in a full tank changes after the addition of salt,the diff erence in the peak is linear with the increase in the conductivity of water.This result provides an experimental basis for the design of a transient electromagnetic logging instrument that measures the conductivity of formation in cased well.展开更多
In order to achieve the optimized design of a cased telescoped ammunition(CTA) interior ballistic design,a genetic algorithm was introduced into the optimal design of CTA interior ballistics with coupling the CTA inte...In order to achieve the optimized design of a cased telescoped ammunition(CTA) interior ballistic design,a genetic algorithm was introduced into the optimal design of CTA interior ballistics with coupling the CTA interior ballistic model. Aiming at the interior ballistic characteristics of a CTA gun, the goal of CTA interior ballistic design is to obtain a projectile velocity as large as possible. The optimal design of CTA interior ballistic is carried out using a genetic algorithm by setting peak pressure, changing the chamber volume and gun powder charge density. A numerical simulation of interior ballistics based on a 35 mm CTA firing experimental scheme was conducted and then the genetic algorithm was used for numerical optimization. The projectile muzzle velocity of the optimized scheme is increased from 1168 m/s for the initial experimental scheme to 1182 m/s. Then four optimization schemes were obtained with several independent optimization processes. The schemes were compared with each other and the difference between these schemes is small. The peak pressure and muzzle velocity of these schemes are almost the same. The result shows that the genetic algorithm is effective in the optimal design of the CTA interior ballistics. This work will be lay the foundation for further CTA interior ballistic design.展开更多
Transducers that are widely applied in cement bond evaluation tools, such as cement bond logs and variable density logs, cannot radiate acoustic energy directionally because of the characteristics of monopole sources....Transducers that are widely applied in cement bond evaluation tools, such as cement bond logs and variable density logs, cannot radiate acoustic energy directionally because of the characteristics of monopole sources. A phased arc array transmitter, which is a novel transducer that differs from monopole and dipole transducers, is presented in this study. To simulate the acoustic field generated by a phased arc array in a fluid-filled cased borehole with different channelings, a 3D finite-difference time-domain method is adopted. The acoustic field generated by a traditional monopole source is also simulated and compared with the field generated by the phased arc array transmitter. Numerical simulation results show that the phased arc array radiates energy directionally in a narrow angular range in the borehole, thereby compressing the acoustic energy into a narrow range in the casing pipe, the cement, and the formation. We present the analyses of first-arrival waveforms and the amplitudes of casing waves at different azimuthal angles for the two different sources. The results indicate that employing a directional source facilitates azimuthal identification and analysis of possible channeling behind the casing pipe.展开更多
The prediction of the fragment velocity distribution of a cylindrical cased charge with end caps is one of the key issues to assess the damage efficiency of the warhead. However, limited work has been conducted to pre...The prediction of the fragment velocity distribution of a cylindrical cased charge with end caps is one of the key issues to assess the damage efficiency of the warhead. However, limited work has been conducted to predict the fragment velocity distributions along the axis of cylindrical cased charges with end caps. This paper presents a study of the velocity distribution of fragments caused by the explosion of a cylindrical cased charge with end caps. The fragment velocity distribution and the end cap velocity were determined by an X-ray radiography method, and the axial fragment distribution was determined by witness plates. It was found that the velocities of fragments, especially near the edge, were increased when the end caps were added, and the position of maximum velocity is closer to the non-detonation end. The fragment velocities were increased, and the fragment projection range was decreased with the increase of the thickness of the end cap. A formula for fragment velocity distributions of a cylindrical cased charge with end caps, which is based on Huang’s formula, was proposed by the theoretical analysis and data fitting and validated experimentally. The results indicate that the proposed formula is accurate in predicting the fragment velocity distribution along the axis of a cylindrical cased charge with end caps detonated at one end.展开更多
Crossed-dipole acoustic logging technology is mainly used to measure shear wave and determine the anisotropy or fractures of formation in the fi eld of acoustic logging.Based on the propagation characteristics of dipo...Crossed-dipole acoustic logging technology is mainly used to measure shear wave and determine the anisotropy or fractures of formation in the fi eld of acoustic logging.Based on the propagation characteristics of dipole flexural waves in cased holes,and the wavefi eld of fundamental flexural mode at three bonding conditions:good cement bonding,poorly bonded interface I,and poorly bonded interface II.The dispersion curves of flexural waves are calculated,and the eff ects of cement parameters(elastic parameters and geometric dimensions)on dispersion curves are investigated.The RAI method is used to calculate the dipole full waveforms in a cased hole with conventional or ultralight cement surrounded by a soft formation.Then,the weighted spectral semblance is used to conduct the dispersion analysis of the full waves.The numerical results show that the cutoff frequency of flexural waves exceeds the frequency band of the current dipole logging tools in the well-bonded cased hole with conventional cement in soft formations.However,when ultralight cement is used,the cutoff frequency shifts toward low values,and the ultralight cement bonding is conducive to measuring flexural waves in soft formations.When interface I is poorly bonded,the cutoff frequency shifts toward low values,and the change is evident in soft formations.The cutoff frequency in the case of ultralight cement bonding is more evident than that of conventional cement bonding.If only interface II is poorly bonded,regardless of the cement used,the cutoff frequencies are all below 2 kHz.The dipole full-wave analysis of diff erent bonding conditions further illustrates that the dispersion characteristics of flexural waves are sensitive to the cement bonding quality of cased holes.展开更多
Munitions contain casings that consume explosive energy.The blast load(e.g.,peak overpressure and maximum impulse)intensity generated by ammunition explosion will be lower than that generated by a bare charge with equ...Munitions contain casings that consume explosive energy.The blast load(e.g.,peak overpressure and maximum impulse)intensity generated by ammunition explosion will be lower than that generated by a bare charge with equal mass.To evaluate the blast load of a cased charge under different conditions,the equivalent bare mass needs to be calculated.However,the accuracy of existing correlations strongly depends on the empirical determination of relevant controlling parameters and lacks theoretical clarification.In this paper,new correlations are proposed based on a more rigorous theoretical derivation,considering both the mechanical behaviors of the casing’s material and the change of the polytropic exponent during the expansion process of the explosion products.The controlling parameters are attributed to the rupture radius ratio and the polytropic exponent of detonation products expansion to casing rupture state.The reasonability is validated by both comprehensive numerical simulations with dynamic mechanical constitutive model and theoretical derivations.The results calculated by the new correlation show better agreement with the experimental results than those calculated by previous correlations,and the results difference is explained in more consistency with the thermos-physical properties of the charge and mechanical behaviors of casing material.Furthermore,the correlation of the cased-to-bare impulse ratio is also theoretically improved,providing a more accurate theoretical basis for both the equivalent bare mass and impulse evaluation for a cased charge.展开更多
The study of the thin bed responses and correction methods in cased hole density logging can provide a theoretical basis for research to improve data processing methods. By using the Monte Carlo program MCNP, the chan...The study of the thin bed responses and correction methods in cased hole density logging can provide a theoretical basis for research to improve data processing methods. By using the Monte Carlo program MCNP, the change of detector count from thin beds with the vertical depth was calculated at different casing thicknesses. The calculation showed that with the low density thin bed moving upward, detector count first increased to a maximum then decreased. The responses of a thin bed with a high density were opposite to those of a thin bed with a low density. The change curve was symmetrical, and the maximums or minimums appeared at the midpoint between the detector and source. Besides, detector count increased with increasing thin bed thickness. At a specific thin bed thickness, further increase of thin bed thickness resulted in a slow increase of detector count then the count rate leveled off. In actual logging, the influence of adjacent formations on density log measurements can be ignored. Finally, based on numerical simulation correction methods for the dual influence of casing and thin beds are discussed.展开更多
Starting friction would be induced and preserved somewhere along the seabed route of cased insulated flowlines（CIF） when the pipe carries service loads.The axial pipe-soil interaction can be divided into three pipe ...Starting friction would be induced and preserved somewhere along the seabed route of cased insulated flowlines（CIF） when the pipe carries service loads.The axial pipe-soil interaction can be divided into three pipe sections：the sliding section,the fixed section and the starting friction section.Although limited to a relatively small length of the pipe,the pipe coats of the starting friction section would suffer much higher shear force caused by thermal expansion than those of the sliding section or the fixed section.Based on the axial equilibrium equation of this kind of insulated pipeline,we developed a method for checking the shear force on CIF coats and their interfaces.The typical example shows that starting friction effect should be taken into account when checking the lap shear strength of heatshrinkable sleeves on CIF field joints.展开更多
Cement bond quality evaluations are essential for assessing zonal isolation between formation strata,providing crucial information for ensuring environmental and ecological safety in oil and gas exploitation,geotherma...Cement bond quality evaluations are essential for assessing zonal isolation between formation strata,providing crucial information for ensuring environmental and ecological safety in oil and gas exploitation,geothermal energy injection and geological carbon dioxide sequestration.In the past decade,the ultrasonic pulse-echo and pitch-catch logging techniques have emerged as effective and non-destructive methods for quantitatively eval-uating bond quality at both the casing-cement and cement-formation interfaces.This review presents a comprehensive overview of recent advancements in cement bond quality assessment based on ultrasonic mea-surements.Key developments include automatic waveform quality assessment,inversion techniques for mud and cement impedance,tool trajectory corrections,separation of flexural and extensional mode waves,machine learning-based extraction and enhancement of TIE waveforms,and imaging of the cement-formation interface using the reverse time migration approach.The review thoroughly explores the methodological principles and applications of these techniques,supported by synthetic datasets,full-scale physical well experiments,and field well data.Considering the recent progress in machine learning and the growing availability of advanced computational resources,we highlight the most significant achievements and ongoing challenges in data pro-cessing,while discussing the potential advancements these techniques could offer in the near future.展开更多
The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the disper...The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the dispersion features, excitation spectra and contributions of modes excited in the cased boreholes with different cementing types are studied. The phase velocity dispersion studies of leaky modes show that high-order modes form "plateau" regions with one approximate velocity denoted by v separated by their cutoff frequencies, in which the phase velocity changes little with a considerable frequency range, while the group velocity keeps a relatively constant high value. Usually, the operation frequency range of a specific cementing evaluation acoustic logging tool is covered by such a "plateau" region. Mode excitation and contribution analyses show that the first arrivals in the cased boreholes for the poorly bonded conditions are the contributions from leaky modes, where the traveling velocity of the first arrivals processed by slowness time coherence(STC) method is equal to the approximated velocity v. Analyses on generation of leaky modes in the cased boreholes supplement the understanding of the generation mechanism of the first arrivals.展开更多
Laboratory cased-hole acoustic logging simulations are developed with the linear phased-array transmitter in scaled cased well models for evaluating the feasibility of extracting formation acoustic parameters through ...Laboratory cased-hole acoustic logging simulations are developed with the linear phased-array transmitter in scaled cased well models for evaluating the feasibility of extracting formation acoustic parameters through casing.The full waveforms are measured with different cement bonding models.By analyzing the measured wavetrains and the time-slowness correlation graphs,it is showed that when the generation conditions of the refracted compressional wave and the refracted shear wave are reached successively by regulating the direction of acoustic beam radiated from the linear phased-array transmitter,steered angle of the main radiation lobe with both good bonding interfaces.The refracted compressional wave and the refracted shear wave can be stimulated obviously and the casing wave can be suppressed effectively,even when the casing and cement（or the cement and formation） is not bonded.Based on these observations, it is worthwhile to apply the linear phased-array transmitter to determine formation velocities,particularly in poorly bonded cased well.The works establish the experimental and theoretical foundation for new generation cased-hole acoustic logging tool development.展开更多
Based on the wave equations in cylindrically layered structures and boundary conditions, the frequency equation for axisymmetric guided waves and the expression for sound fields in a cased borehole excited by a monop...Based on the wave equations in cylindrically layered structures and boundary conditions, the frequency equation for axisymmetric guided waves and the expression for sound fields in a cased borehole excited by a monopole or multipole source have been derived. The synthetic full waveforms excited by the monopole and dipole source are simulated using a real axis integration and FFT method. According to the axisymmetric guided wave modes, the synthetic full waveforms and the effects of the interface conditions on the sound field in a cased borehole have been analyzed and studied respectively. Numerical results indicate that it may be difficult to distinguish well bonded, poorly bonded or unbonded intermediate layer between the steel pipe and formation if only using a monopole source or dipole source. To properly estimate the case boundary conditions, a combination of monopole source logging with dipole source logging is suggested.展开更多
介绍了高温蠕变工况下运行的压力容器可能出现的失效模式,结合工程设计现状,指出了我国当前压力容器标准体系在确定高温蠕变工况许用压应力时存在的技术瓶颈,在此基础之上引出ASME Code Case 3029,对其适用范围、发展历程、产生背景及...介绍了高温蠕变工况下运行的压力容器可能出现的失效模式,结合工程设计现状,指出了我国当前压力容器标准体系在确定高温蠕变工况许用压应力时存在的技术瓶颈,在此基础之上引出ASME Code Case 3029,对其适用范围、发展历程、产生背景及工程意义进行了简单的介绍,以某工程设计项目中的实际结构为例,介绍了该方法的使用过程及注意事项,并结合压力容器工程设计领域的实际需求,对我国标准体系下一步的制定或修订方向提出了展望。展开更多
Test case prioritization and ranking play a crucial role in software testing by improving fault detection efficiency and ensuring software reliability.While prioritization selects the most relevant test cases for opti...Test case prioritization and ranking play a crucial role in software testing by improving fault detection efficiency and ensuring software reliability.While prioritization selects the most relevant test cases for optimal coverage,ranking further refines their execution order to detect critical faults earlier.This study investigates machine learning techniques to enhance both prioritization and ranking,contributing to more effective and efficient testing processes.We first employ advanced feature engineering alongside ensemble models,including Gradient Boosted,Support Vector Machines,Random Forests,and Naive Bayes classifiers to optimize test case prioritization,achieving an accuracy score of 0.98847 and significantly improving the Average Percentage of Fault Detection(APFD).Subsequently,we introduce a deep Q-learning framework combined with a Genetic Algorithm(GA)to refine test case ranking within priority levels.This approach achieves a rank accuracy of 0.9172,demonstrating robust performance despite the increasing computational demands of specialized variation operators.Our findings highlight the effectiveness of stacked ensemble learning and reinforcement learning in optimizing test case prioritization and ranking.This integrated approach improves testing efficiency,reduces late-stage defects,and improves overall software stability.The study provides valuable information for AI-driven testing frameworks,paving the way for more intelligent and adaptive software quality assurance methodologies.展开更多
AIM:To report and analyze cases of sterile intraocular inflammation(IOI)following intravitreal faricimab injections in patients treated for neovascular age-related macular degeneration(nAMD)and diabetic macular edema(...AIM:To report and analyze cases of sterile intraocular inflammation(IOI)following intravitreal faricimab injections in patients treated for neovascular age-related macular degeneration(nAMD)and diabetic macular edema(DME).METHODS:This double-center case series included nine eyes of six patients who developed uveitis after faricimab therapy.Comprehensive clinical evaluation was performed,including slit-lamp examination,intraocular pressure(IOP)measurement,fluorescein and indocyanine green angiography(ICGA),and laboratory tests.Inflammatory responses were treated with topical or systemic corticosteroids,and patients were monitored for visual acuity and inflammatory activity.RESULTS:The incidence of IOI was 0.8%per patient(Innsbruck)and 0.23%(Czechia),with inflammation typically occurring between the third and sixth injection(mean interval:10d post-injection).Inflammator y presentations ranged from anterior uveitis to posterior segment involvement.One notable case demonstrated novel choroidal hypofluorescent lesions on angiography,suggesting deeper ocular involvement.The mean patient age was 76y;five of six affected patients were female.All cases responded to local and systemic corticosteroids,with full recovery of initial visual acuity.CONCLUSION:Sterile IOI after faricimab appears to be a rare but relevant adverse event.Although the incidence falls within expected ranges for anti-vascular endothelial growth factor(anti-VEGF)agents,the observed choroidal involvement represents a potentially new safety signal.Prompt diagnosis and corticosteroid therapy are effective in all cases.Our findings support the need for vigilant post-marketing surveillance and further studies to better understand the underlying mechanisms and risk factors of faricimab-associated inflammation.展开更多
BACKGROUND Congenital hypothyroidism(CH)is a common condition in both preterm and term infants characterized by either thyroid gland absence or hypofunctionality.The clinical association of refractory lactic acidosis ...BACKGROUND Congenital hypothyroidism(CH)is a common condition in both preterm and term infants characterized by either thyroid gland absence or hypofunctionality.The clinical association of refractory lactic acidosis and heart failure has rarely been observed in cases of pediatric patients with CH pathology.Here,we explored the etiological relationship between CH,heart failure,and refractory lactic acidosis to reflect the importance of thyroid function screening in neonates with heart disease.CASE SUMMARY A 33-day-old extremely premature female infant presented with tachypnea,respiratory distress,recurrent infections,and abdominal distension postnatal.On admission to our facility,she had cardiomegaly,hepatomegaly,and lactic acidosis(revealed on blood gas analysis),with lactate progressively rising to 25 mmol/L.Chest radiographs showed pulmonary congestion,while echocardiography revealed cardiac enlargement,left ventricular wall thickening,and pericardial effusion.Initial management aimed at correcting acidosis and treating heart failure proved ineffective.After reassessment,thyroid function tests showed significantly decreased triiodothyronine,free triiodothyronine,thyroxine,and free thyroxine levels,with a significantly increased thyroidstimulating hormone level,confirming a CH diagnosis.Levothyroxine was administered,resulting in rapid correction of lactic acidosis and gradual improvement of thyroid function and systemic symptoms,culminating in full recovery and discharge.We also reviewed the relevant literature on thyroid and cardiac dysfunctions in order to explore their deeper association.CONCLUSION This case links CH-induced heart failure with refractory lactic acidosis,urging prompt thyroid screening in affected neonates to reduce mortality.展开更多
Background:Urologic cancers typically metastasize to common organs,while spread to sites such as the heart,hand,cranial bones,penis,or tonsil is exceedingly rare.The clinical relevance and prognostic impact of these u...Background:Urologic cancers typically metastasize to common organs,while spread to sites such as the heart,hand,cranial bones,penis,or tonsil is exceedingly rare.The clinical relevance and prognostic impact of these unusual metastases remain unclear.This case series highlights six exceptional cases,providing unique insights to support awareness and management.Case Description:We retrospectively analyzed six cases of patients diagnosed with urologic cancers who developed metastases at uncommon sites.Each case was evaluated based on clinical presentation,imaging findings,histopathological confirmation,treatment course,and outcomes.Relevant literature was reviewed to contextualize findings.Among the six cases,metastatic involvement was identified in atypical locations including the right atrium(testicular cancer),hand(bladder cancer),perineum and penis(sarcomatoid bladder cancer),cranial bones(prostate cancer),penis(rectal cancer),and tonsillar region(renal pelvis rhabdomyosarcoma).Timely imaging and histopathological confirmation guided personalized treatment strategies,primarily involving surgical interventions.Despite aggressive treatments,the prognosis remained poor in most cases,reflecting the aggressive nature of these metastases.Conclusion:Rare metastases from urologic malignancies,although uncommon,have significant implications on patient management.Early detection through advanced imaging and aggressive multimodal interventions are pivotal for improving outcomes.Awareness of such atypical metastatic patterns is essential for clinicians managing urologic cancers.展开更多
BACKGROUND Edwardsiella tarda(E.tarda)belongs to the family Enterobacteriaceae and is generally seen to cause infections mainly in fish,but is also capable of infecting humans.Extraintestinal infections occur in patie...BACKGROUND Edwardsiella tarda(E.tarda)belongs to the family Enterobacteriaceae and is generally seen to cause infections mainly in fish,but is also capable of infecting humans.Extraintestinal infections occur in patients with certain risk factors,including immunocompromised status.We recently diagnosed a case of spontaneous bacterial peritonitis(SBP)due to E.tarda in an immuno-compromised dialysis patient.CASE SUMMARY Patient was a 55-year-old male,with a history of diabetic nephropathy being treated with hemodialysis three times a week.He was referred to our hospital due to an increased volume of ascites,and blood examination revealed increased inflammatory reaction.At our emergency department,he developed fever,disturbance of consciousness,abdominal distension,and abdomen-wide pain.In addition,a dialysis shunt was confirmed in his right forearm,and the shunt site showed no signs of inflammation.No wounds were confirmed on or in his body.A blood examination revealed increased values of white blood cells,C-reactive protein,and creatinine.Plain chest and abdominal computed tomography scanning revealed increased ascites volume.Abdominal paracentesis was performed and a Gram stain revealed Gramnegative bacillus.These findings prompted diagnosis of SBP.The patient was admitted and treated with cefmetazole,causing fever resolution and symptom improvements.Later,E.tarda was identified in ascites culture.The patient improved with decreased inflammatory response and was discharged on the 12th day of hospitalization.The antibiotic was terminated after 14 days of treatment.SBP in this case may have developed from chronic renal failure and diabetes mellitus.CONCLUSION We report the first known case of SBP due to E.tarda in an immuno-compromised dialysis patient.展开更多
Aconitines are a group of highly bioactive and toxic compounds found in aconitum species.[1]It is clinically used to treat rheumatism,rheumatoid arthritis,osteoarthritis,and cancer.[2]In folk medicine,aconitine is oft...Aconitines are a group of highly bioactive and toxic compounds found in aconitum species.[1]It is clinically used to treat rheumatism,rheumatoid arthritis,osteoarthritis,and cancer.[2]In folk medicine,aconitine is often soaked in white wine to make medicinal wine,which is used to treat rheumatism,joint pain,and other diseases.[3]Improper use of aconitine can cause adverse effects in the nervous system and digestive system,as well as cardiovascular dysfunction,especially arrhythmia.[4]Because of its high toxicity when it is improperly handled,aconitine has attracted widespread attention.展开更多
基金supported by the National Natural Science Foundation of China (grant nos. 42074137)。
文摘A cased well model consists of a coaxial tank and casing,which houses coaxially installed transmitting and receiving coils.The transmitting coil is excited by the current produced by the transmitting circuit,and transient electromagnetic responses occur in the casing,including direct coupling and casing responses.As the range between the transmitting and receiving coils increases,direct coupling responses decay rapidly,are less than the casing response at 0.3 m,and disappear at 0.7 m.By contrast,a casing response increases rapidly and then declines slowly after reaching a peak and changes little within a specifi c range.The peak decreases slowly with range.The continuous addition of water to the tank causes slight changes in transient electromagnetic responses,so the diff erence which are subtracted from the response without water is used.Moreover,the diff erences at the time of rapid increase in response and the time of rapid decrease in response are large,forming a peak and a trough.Given that the conductivity of water in a full tank changes after the addition of salt,the diff erence in the peak is linear with the increase in the conductivity of water.This result provides an experimental basis for the design of a transient electromagnetic logging instrument that measures the conductivity of formation in cased well.
文摘In order to achieve the optimized design of a cased telescoped ammunition(CTA) interior ballistic design,a genetic algorithm was introduced into the optimal design of CTA interior ballistics with coupling the CTA interior ballistic model. Aiming at the interior ballistic characteristics of a CTA gun, the goal of CTA interior ballistic design is to obtain a projectile velocity as large as possible. The optimal design of CTA interior ballistic is carried out using a genetic algorithm by setting peak pressure, changing the chamber volume and gun powder charge density. A numerical simulation of interior ballistics based on a 35 mm CTA firing experimental scheme was conducted and then the genetic algorithm was used for numerical optimization. The projectile muzzle velocity of the optimized scheme is increased from 1168 m/s for the initial experimental scheme to 1182 m/s. Then four optimization schemes were obtained with several independent optimization processes. The schemes were compared with each other and the difference between these schemes is small. The peak pressure and muzzle velocity of these schemes are almost the same. The result shows that the genetic algorithm is effective in the optimal design of the CTA interior ballistics. This work will be lay the foundation for further CTA interior ballistic design.
基金supported by the National Natural ScienceFoundation of China (Grant Nos. 11204380, 11374371, 11134011 and 61102102)National Science and Technology Major Project (Grant No. 2011ZX05020-009)PetroChina Innovation Foundation (2013D-5006-0304)
文摘Transducers that are widely applied in cement bond evaluation tools, such as cement bond logs and variable density logs, cannot radiate acoustic energy directionally because of the characteristics of monopole sources. A phased arc array transmitter, which is a novel transducer that differs from monopole and dipole transducers, is presented in this study. To simulate the acoustic field generated by a phased arc array in a fluid-filled cased borehole with different channelings, a 3D finite-difference time-domain method is adopted. The acoustic field generated by a traditional monopole source is also simulated and compared with the field generated by the phased arc array transmitter. Numerical simulation results show that the phased arc array radiates energy directionally in a narrow angular range in the borehole, thereby compressing the acoustic energy into a narrow range in the casing pipe, the cement, and the formation. We present the analyses of first-arrival waveforms and the amplitudes of casing waves at different azimuthal angles for the two different sources. The results indicate that employing a directional source facilitates azimuthal identification and analysis of possible channeling behind the casing pipe.
基金financial support from the exploratory project of State Key Laboratory of Explosion Science and Technology, China (No. QNKT19-09)。
文摘The prediction of the fragment velocity distribution of a cylindrical cased charge with end caps is one of the key issues to assess the damage efficiency of the warhead. However, limited work has been conducted to predict the fragment velocity distributions along the axis of cylindrical cased charges with end caps. This paper presents a study of the velocity distribution of fragments caused by the explosion of a cylindrical cased charge with end caps. The fragment velocity distribution and the end cap velocity were determined by an X-ray radiography method, and the axial fragment distribution was determined by witness plates. It was found that the velocities of fragments, especially near the edge, were increased when the end caps were added, and the position of maximum velocity is closer to the non-detonation end. The fragment velocities were increased, and the fragment projection range was decreased with the increase of the thickness of the end cap. A formula for fragment velocity distributions of a cylindrical cased charge with end caps, which is based on Huang’s formula, was proposed by the theoretical analysis and data fitting and validated experimentally. The results indicate that the proposed formula is accurate in predicting the fragment velocity distribution along the axis of a cylindrical cased charge with end caps detonated at one end.
基金supported by the National Natural Science Foundation of China(Grants 41474098 and 42074139).
文摘Crossed-dipole acoustic logging technology is mainly used to measure shear wave and determine the anisotropy or fractures of formation in the fi eld of acoustic logging.Based on the propagation characteristics of dipole flexural waves in cased holes,and the wavefi eld of fundamental flexural mode at three bonding conditions:good cement bonding,poorly bonded interface I,and poorly bonded interface II.The dispersion curves of flexural waves are calculated,and the eff ects of cement parameters(elastic parameters and geometric dimensions)on dispersion curves are investigated.The RAI method is used to calculate the dipole full waveforms in a cased hole with conventional or ultralight cement surrounded by a soft formation.Then,the weighted spectral semblance is used to conduct the dispersion analysis of the full waves.The numerical results show that the cutoff frequency of flexural waves exceeds the frequency band of the current dipole logging tools in the well-bonded cased hole with conventional cement in soft formations.However,when ultralight cement is used,the cutoff frequency shifts toward low values,and the ultralight cement bonding is conducive to measuring flexural waves in soft formations.When interface I is poorly bonded,the cutoff frequency shifts toward low values,and the change is evident in soft formations.The cutoff frequency in the case of ultralight cement bonding is more evident than that of conventional cement bonding.If only interface II is poorly bonded,regardless of the cement used,the cutoff frequencies are all below 2 kHz.The dipole full-wave analysis of diff erent bonding conditions further illustrates that the dispersion characteristics of flexural waves are sensitive to the cement bonding quality of cased holes.
文摘Munitions contain casings that consume explosive energy.The blast load(e.g.,peak overpressure and maximum impulse)intensity generated by ammunition explosion will be lower than that generated by a bare charge with equal mass.To evaluate the blast load of a cased charge under different conditions,the equivalent bare mass needs to be calculated.However,the accuracy of existing correlations strongly depends on the empirical determination of relevant controlling parameters and lacks theoretical clarification.In this paper,new correlations are proposed based on a more rigorous theoretical derivation,considering both the mechanical behaviors of the casing’s material and the change of the polytropic exponent during the expansion process of the explosion products.The controlling parameters are attributed to the rupture radius ratio and the polytropic exponent of detonation products expansion to casing rupture state.The reasonability is validated by both comprehensive numerical simulations with dynamic mechanical constitutive model and theoretical derivations.The results calculated by the new correlation show better agreement with the experimental results than those calculated by previous correlations,and the results difference is explained in more consistency with the thermos-physical properties of the charge and mechanical behaviors of casing material.Furthermore,the correlation of the cased-to-bare impulse ratio is also theoretically improved,providing a more accurate theoretical basis for both the equivalent bare mass and impulse evaluation for a cased charge.
文摘The study of the thin bed responses and correction methods in cased hole density logging can provide a theoretical basis for research to improve data processing methods. By using the Monte Carlo program MCNP, the change of detector count from thin beds with the vertical depth was calculated at different casing thicknesses. The calculation showed that with the low density thin bed moving upward, detector count first increased to a maximum then decreased. The responses of a thin bed with a high density were opposite to those of a thin bed with a low density. The change curve was symmetrical, and the maximums or minimums appeared at the midpoint between the detector and source. Besides, detector count increased with increasing thin bed thickness. At a specific thin bed thickness, further increase of thin bed thickness resulted in a slow increase of detector count then the count rate leveled off. In actual logging, the influence of adjacent formations on density log measurements can be ignored. Finally, based on numerical simulation correction methods for the dual influence of casing and thin beds are discussed.
文摘Starting friction would be induced and preserved somewhere along the seabed route of cased insulated flowlines（CIF） when the pipe carries service loads.The axial pipe-soil interaction can be divided into three pipe sections：the sliding section,the fixed section and the starting friction section.Although limited to a relatively small length of the pipe,the pipe coats of the starting friction section would suffer much higher shear force caused by thermal expansion than those of the sliding section or the fixed section.Based on the axial equilibrium equation of this kind of insulated pipeline,we developed a method for checking the shear force on CIF coats and their interfaces.The typical example shows that starting friction effect should be taken into account when checking the lap shear strength of heatshrinkable sleeves on CIF field joints.
基金supported by a National Natural Science Foundation of China(Grant numbers 42474167,41974150,42174158,W2522002)Natural Science Basic Research Program of Shaanxi(2023-JC-YB-220)the Shenzhen Science and Technology Program(grant numbers JCYJ20230807120007015 and RCJC20231211085916003).
文摘Cement bond quality evaluations are essential for assessing zonal isolation between formation strata,providing crucial information for ensuring environmental and ecological safety in oil and gas exploitation,geothermal energy injection and geological carbon dioxide sequestration.In the past decade,the ultrasonic pulse-echo and pitch-catch logging techniques have emerged as effective and non-destructive methods for quantitatively eval-uating bond quality at both the casing-cement and cement-formation interfaces.This review presents a comprehensive overview of recent advancements in cement bond quality assessment based on ultrasonic mea-surements.Key developments include automatic waveform quality assessment,inversion techniques for mud and cement impedance,tool trajectory corrections,separation of flexural and extensional mode waves,machine learning-based extraction and enhancement of TIE waveforms,and imaging of the cement-formation interface using the reverse time migration approach.The review thoroughly explores the methodological principles and applications of these techniques,supported by synthetic datasets,full-scale physical well experiments,and field well data.Considering the recent progress in machine learning and the growing availability of advanced computational resources,we highlight the most significant achievements and ongoing challenges in data pro-cessing,while discussing the potential advancements these techniques could offer in the near future.
基金the National Natural Science Foundation of China(Grant Nos.11134011 and 41274134)
文摘The generation mechanism of the first arrivals in the cased boreholes for the poorly bonded conditions is investigated. Based on the analyses of the Riemann surface structure of the characteristic function, the dispersion features, excitation spectra and contributions of modes excited in the cased boreholes with different cementing types are studied. The phase velocity dispersion studies of leaky modes show that high-order modes form "plateau" regions with one approximate velocity denoted by v separated by their cutoff frequencies, in which the phase velocity changes little with a considerable frequency range, while the group velocity keeps a relatively constant high value. Usually, the operation frequency range of a specific cementing evaluation acoustic logging tool is covered by such a "plateau" region. Mode excitation and contribution analyses show that the first arrivals in the cased boreholes for the poorly bonded conditions are the contributions from leaky modes, where the traveling velocity of the first arrivals processed by slowness time coherence(STC) method is equal to the approximated velocity v. Analyses on generation of leaky modes in the cased boreholes supplement the understanding of the generation mechanism of the first arrivals.
基金supported by the National Natural Science Foundation of China(40804020)Natural Science Foundation of Shandong(ZR2011DQ020)
文摘Laboratory cased-hole acoustic logging simulations are developed with the linear phased-array transmitter in scaled cased well models for evaluating the feasibility of extracting formation acoustic parameters through casing.The full waveforms are measured with different cement bonding models.By analyzing the measured wavetrains and the time-slowness correlation graphs,it is showed that when the generation conditions of the refracted compressional wave and the refracted shear wave are reached successively by regulating the direction of acoustic beam radiated from the linear phased-array transmitter,steered angle of the main radiation lobe with both good bonding interfaces.The refracted compressional wave and the refracted shear wave can be stimulated obviously and the casing wave can be suppressed effectively,even when the casing and cement（or the cement and formation） is not bonded.Based on these observations, it is worthwhile to apply the linear phased-array transmitter to determine formation velocities,particularly in poorly bonded cased well.The works establish the experimental and theoretical foundation for new generation cased-hole acoustic logging tool development.
基金The project is supported by the National Natural Science Foundation of China and Natural ScienceFoundation of Jiangsu Province
文摘Based on the wave equations in cylindrically layered structures and boundary conditions, the frequency equation for axisymmetric guided waves and the expression for sound fields in a cased borehole excited by a monopole or multipole source have been derived. The synthetic full waveforms excited by the monopole and dipole source are simulated using a real axis integration and FFT method. According to the axisymmetric guided wave modes, the synthetic full waveforms and the effects of the interface conditions on the sound field in a cased borehole have been analyzed and studied respectively. Numerical results indicate that it may be difficult to distinguish well bonded, poorly bonded or unbonded intermediate layer between the steel pipe and formation if only using a monopole source or dipole source. To properly estimate the case boundary conditions, a combination of monopole source logging with dipole source logging is suggested.
文摘介绍了高温蠕变工况下运行的压力容器可能出现的失效模式,结合工程设计现状,指出了我国当前压力容器标准体系在确定高温蠕变工况许用压应力时存在的技术瓶颈,在此基础之上引出ASME Code Case 3029,对其适用范围、发展历程、产生背景及工程意义进行了简单的介绍,以某工程设计项目中的实际结构为例,介绍了该方法的使用过程及注意事项,并结合压力容器工程设计领域的实际需求,对我国标准体系下一步的制定或修订方向提出了展望。
文摘Test case prioritization and ranking play a crucial role in software testing by improving fault detection efficiency and ensuring software reliability.While prioritization selects the most relevant test cases for optimal coverage,ranking further refines their execution order to detect critical faults earlier.This study investigates machine learning techniques to enhance both prioritization and ranking,contributing to more effective and efficient testing processes.We first employ advanced feature engineering alongside ensemble models,including Gradient Boosted,Support Vector Machines,Random Forests,and Naive Bayes classifiers to optimize test case prioritization,achieving an accuracy score of 0.98847 and significantly improving the Average Percentage of Fault Detection(APFD).Subsequently,we introduce a deep Q-learning framework combined with a Genetic Algorithm(GA)to refine test case ranking within priority levels.This approach achieves a rank accuracy of 0.9172,demonstrating robust performance despite the increasing computational demands of specialized variation operators.Our findings highlight the effectiveness of stacked ensemble learning and reinforcement learning in optimizing test case prioritization and ranking.This integrated approach improves testing efficiency,reduces late-stage defects,and improves overall software stability.The study provides valuable information for AI-driven testing frameworks,paving the way for more intelligent and adaptive software quality assurance methodologies.
文摘AIM:To report and analyze cases of sterile intraocular inflammation(IOI)following intravitreal faricimab injections in patients treated for neovascular age-related macular degeneration(nAMD)and diabetic macular edema(DME).METHODS:This double-center case series included nine eyes of six patients who developed uveitis after faricimab therapy.Comprehensive clinical evaluation was performed,including slit-lamp examination,intraocular pressure(IOP)measurement,fluorescein and indocyanine green angiography(ICGA),and laboratory tests.Inflammatory responses were treated with topical or systemic corticosteroids,and patients were monitored for visual acuity and inflammatory activity.RESULTS:The incidence of IOI was 0.8%per patient(Innsbruck)and 0.23%(Czechia),with inflammation typically occurring between the third and sixth injection(mean interval:10d post-injection).Inflammator y presentations ranged from anterior uveitis to posterior segment involvement.One notable case demonstrated novel choroidal hypofluorescent lesions on angiography,suggesting deeper ocular involvement.The mean patient age was 76y;five of six affected patients were female.All cases responded to local and systemic corticosteroids,with full recovery of initial visual acuity.CONCLUSION:Sterile IOI after faricimab appears to be a rare but relevant adverse event.Although the incidence falls within expected ranges for anti-vascular endothelial growth factor(anti-VEGF)agents,the observed choroidal involvement represents a potentially new safety signal.Prompt diagnosis and corticosteroid therapy are effective in all cases.Our findings support the need for vigilant post-marketing surveillance and further studies to better understand the underlying mechanisms and risk factors of faricimab-associated inflammation.
文摘BACKGROUND Congenital hypothyroidism(CH)is a common condition in both preterm and term infants characterized by either thyroid gland absence or hypofunctionality.The clinical association of refractory lactic acidosis and heart failure has rarely been observed in cases of pediatric patients with CH pathology.Here,we explored the etiological relationship between CH,heart failure,and refractory lactic acidosis to reflect the importance of thyroid function screening in neonates with heart disease.CASE SUMMARY A 33-day-old extremely premature female infant presented with tachypnea,respiratory distress,recurrent infections,and abdominal distension postnatal.On admission to our facility,she had cardiomegaly,hepatomegaly,and lactic acidosis(revealed on blood gas analysis),with lactate progressively rising to 25 mmol/L.Chest radiographs showed pulmonary congestion,while echocardiography revealed cardiac enlargement,left ventricular wall thickening,and pericardial effusion.Initial management aimed at correcting acidosis and treating heart failure proved ineffective.After reassessment,thyroid function tests showed significantly decreased triiodothyronine,free triiodothyronine,thyroxine,and free thyroxine levels,with a significantly increased thyroidstimulating hormone level,confirming a CH diagnosis.Levothyroxine was administered,resulting in rapid correction of lactic acidosis and gradual improvement of thyroid function and systemic symptoms,culminating in full recovery and discharge.We also reviewed the relevant literature on thyroid and cardiac dysfunctions in order to explore their deeper association.CONCLUSION This case links CH-induced heart failure with refractory lactic acidosis,urging prompt thyroid screening in affected neonates to reduce mortality.
文摘Background:Urologic cancers typically metastasize to common organs,while spread to sites such as the heart,hand,cranial bones,penis,or tonsil is exceedingly rare.The clinical relevance and prognostic impact of these unusual metastases remain unclear.This case series highlights six exceptional cases,providing unique insights to support awareness and management.Case Description:We retrospectively analyzed six cases of patients diagnosed with urologic cancers who developed metastases at uncommon sites.Each case was evaluated based on clinical presentation,imaging findings,histopathological confirmation,treatment course,and outcomes.Relevant literature was reviewed to contextualize findings.Among the six cases,metastatic involvement was identified in atypical locations including the right atrium(testicular cancer),hand(bladder cancer),perineum and penis(sarcomatoid bladder cancer),cranial bones(prostate cancer),penis(rectal cancer),and tonsillar region(renal pelvis rhabdomyosarcoma).Timely imaging and histopathological confirmation guided personalized treatment strategies,primarily involving surgical interventions.Despite aggressive treatments,the prognosis remained poor in most cases,reflecting the aggressive nature of these metastases.Conclusion:Rare metastases from urologic malignancies,although uncommon,have significant implications on patient management.Early detection through advanced imaging and aggressive multimodal interventions are pivotal for improving outcomes.Awareness of such atypical metastatic patterns is essential for clinicians managing urologic cancers.
文摘BACKGROUND Edwardsiella tarda(E.tarda)belongs to the family Enterobacteriaceae and is generally seen to cause infections mainly in fish,but is also capable of infecting humans.Extraintestinal infections occur in patients with certain risk factors,including immunocompromised status.We recently diagnosed a case of spontaneous bacterial peritonitis(SBP)due to E.tarda in an immuno-compromised dialysis patient.CASE SUMMARY Patient was a 55-year-old male,with a history of diabetic nephropathy being treated with hemodialysis three times a week.He was referred to our hospital due to an increased volume of ascites,and blood examination revealed increased inflammatory reaction.At our emergency department,he developed fever,disturbance of consciousness,abdominal distension,and abdomen-wide pain.In addition,a dialysis shunt was confirmed in his right forearm,and the shunt site showed no signs of inflammation.No wounds were confirmed on or in his body.A blood examination revealed increased values of white blood cells,C-reactive protein,and creatinine.Plain chest and abdominal computed tomography scanning revealed increased ascites volume.Abdominal paracentesis was performed and a Gram stain revealed Gramnegative bacillus.These findings prompted diagnosis of SBP.The patient was admitted and treated with cefmetazole,causing fever resolution and symptom improvements.Later,E.tarda was identified in ascites culture.The patient improved with decreased inflammatory response and was discharged on the 12th day of hospitalization.The antibiotic was terminated after 14 days of treatment.SBP in this case may have developed from chronic renal failure and diabetes mellitus.CONCLUSION We report the first known case of SBP due to E.tarda in an immuno-compromised dialysis patient.
基金supported by grants from the National Natural Science Foundation of China(82360387)the Key Laboratory of Emergency Medicine of Yunnan Province(202449CE340015).
文摘Aconitines are a group of highly bioactive and toxic compounds found in aconitum species.[1]It is clinically used to treat rheumatism,rheumatoid arthritis,osteoarthritis,and cancer.[2]In folk medicine,aconitine is often soaked in white wine to make medicinal wine,which is used to treat rheumatism,joint pain,and other diseases.[3]Improper use of aconitine can cause adverse effects in the nervous system and digestive system,as well as cardiovascular dysfunction,especially arrhythmia.[4]Because of its high toxicity when it is improperly handled,aconitine has attracted widespread attention.
