China has embarked on an extensive and sustained endeavor to harness its coal resources for a substantial period.However,the depletion of coal reserves in mining regions has necessitated the closure or abandonment of ...China has embarked on an extensive and sustained endeavor to harness its coal resources for a substantial period.However,the depletion of coal reserves in mining regions has necessitated the closure or abandonment of numerous mines,resulting in a marked increase in the number of such facilities.Parallel to this,China is vigorously advancing the development of a novel energy power system,aimed at transitioning the power sector from a high-carbon,fossil fuel-dependent paradigm to a low-carbon,clean energy footing.展开更多
We report a high-average-power acousto-optic(AO)Q-switched intracavity frequency-doubled red laser based on a high-efficiency light-emitting-diode(LED)pumped two-rod Nd,Ce:YAG laser module.Under quasi-continuous wave ...We report a high-average-power acousto-optic(AO)Q-switched intracavity frequency-doubled red laser based on a high-efficiency light-emitting-diode(LED)pumped two-rod Nd,Ce:YAG laser module.Under quasi-continuous wave operation conditions,a maximum output power of 1319.08 nm wavelength was achieved at 11.26 W at a repetition rate of 100 Hz.展开更多
We show that the nonlinear stage of the dual-wavelength pumped modulation instability(MI)in nonlinear Schrödinger equation(NLSE)can be effectively analyzed by mode truncation methods.The resulting complicated het...We show that the nonlinear stage of the dual-wavelength pumped modulation instability(MI)in nonlinear Schrödinger equation(NLSE)can be effectively analyzed by mode truncation methods.The resulting complicated heteroclinic structure of instability unveils all possible dynamic trajectories of nonlinear waves.Significantly,the latticed-Fermi-Pasta-Ulam recurrences on the modulated-wave background in NLSE are also investigated and their dynamic trajectories run along the Hamiltonian contours of the heteroclinic structure.It is demonstrated that there has much richer dynamic behavior,in contrast to the nonlinear waves reported before.This novel nonlinear wave promises to inject new vitality into the study of MI.展开更多
During the construction and operation of the abandoned mine pumped storage power station,the underground space surrounding rock body faces the complex stress environment under the action of mining disturbance,frequent...During the construction and operation of the abandoned mine pumped storage power station,the underground space surrounding rock body faces the complex stress environment under the action of mining disturbance,frequent pumping,water storage and other dynamic disturbances.The stability of the abandoned mine surrounding rock body is the basis for guaranteeing the safety and effectiveness of water storage in the underground space of the abandoned mine.By considering the two main factors of different stress levels and disturbance amplitudes,the mechanical properties,damage characteristics and acoustic emission characteristics of the abandoned mine perimeter rock body under dynamic disturbance were investigated using a creep-disturbed dynamic impact loading system.The experimental results show that:1)The stress level is considered to be the major contributing factor of the failure of muddy sandstone,followed by the amplitude of the disturbances;2)The time required for the destruction of muddy sandstone decreases with the increase of amplitude.When the stress level is 80%,the sandstone specimens have a decreasing number of cycles as the disturbance amplitude increases.The disturbance amplitude is sequentially increased from 4 MPa to 5,6,7,and 8 MPa,the number of cycles required for specimen destruction decreases significantly by 96.71%,99.13%,99.60%,and 99.93%,respectively;3)Disturbance amplitude and stress level have a significant effect on muddy sandstone damage and damage occurs only after a certain threshold is reached.With the increase of stress level and disturbance amplitude,the macroscopic damage of muddy sandstone is mainly conical,with obvious flake spalling and poor damage integrity;4)According to the time-dependent changes in AE energy and ringing counts,the acoustic emission activity during the failure process could be divided into three phases,namely,weakening period,smooth period,and surge period,corresponding to the compaction phase,elastic rise phase and post-peak damage phase.The research results are of reference significance for the damage evolution analysis of muddy sandstone under dynamic disturbance and the safety and stability of abandoned mine perimeter rock body.展开更多
Within the framework of achieving carbon neutrality,various industries are confronted with fresh challenges.The ongoing process of downsizing coal industry operations has evolved into a new phase,with the burgeoning p...Within the framework of achieving carbon neutrality,various industries are confronted with fresh challenges.The ongoing process of downsizing coal industry operations has evolved into a new phase,with the burgeoning proliferation of abandoned mines posing a persistent issue.Addressing the challenges and opportunities presented by these abandoned mines,this paper advocates for a scientific approach centered on the advancement of pumped storage energy alongside gas-oil complementary energy.Leveraging abandoned mine tunnels to establish pumped storage power stations holds significant ecological and economic importance for repurposing these sites.This initiative not only serves as an effective means to restore the ecological balance in mining regions but also provides an environmentally friendly approach to repurposing abandoned mine tunnels,offering a blueprint for economically viable pumped storage power stations.This article delineates five crucial scientific considerations and outlines seven primary models for the utilization of abandoned mine sites,delineating a novel,comprehensive pathway for energy and power development that emphasizes multi-energy complementarity and synergistic optimization within abandoned mines.展开更多
Every year in China,a significant number of mines are closed or abandoned.The pumped hydroelectric storage(PHS)and geothermal utilization are vital means to efficiently repurpose resources in abandoned mine.In this wo...Every year in China,a significant number of mines are closed or abandoned.The pumped hydroelectric storage(PHS)and geothermal utilization are vital means to efficiently repurpose resources in abandoned mine.In this work,the development potentials of the PHS and geothermal utilization systems were evaluated.Considering the geological conditions and meteorological data available of Jiahe abandoned mine,a simple evaluation model for PHS and geothermal utilization was established.The average efficiency of the PHS system exceeds 70%and the regulatable energy of a unit volume is over 1.53 kW·h/m^(3).The PHS system achieves optimal performance when the wind/solar power ratio reaches 0.6 and 0.3 in daily and year scale,respectively.In the geothermal utilization system,the outlet temperature and heat production are significantly affected by the injection flow rate.The heat production performance is more stable at lower rate flow,and the proportion of heat production is higher in the initial stage at greater flow rate.As the operating time increases,the proportion of heat production gradually decreases.The cyclic heat storage status has obvious advantages in heat generation and cooling.Furthermore,the energy-saving and emission reduction benefits of PHS and geothermal utilization systems were calculated.展开更多
Based on global initiatives such as the clean energy transition and the development of renewable energy,the pumped storage power station has become a new and significant way of energy storage and regulation,and its co...Based on global initiatives such as the clean energy transition and the development of renewable energy,the pumped storage power station has become a new and significant way of energy storage and regulation,and its construction environment is more complex than that of a traditional reservoir.In particular,the stability of the rock strata in the underground reservoirs is affected by the seepage pressure and rock stress,which presents some challenges in achieving engineering safety and stability.Using the advantages of the numerical simulation method in dealing deal with nonlinear problems in engineering stability,in this study,the stability of the underground reservoir of the Shidangshan(SDS)pumped storage power station was numerically calculated and quantitatively analyzed based on fluid-structure coupling theory,providing an important reference for the safe operation and management of the underground reservoir.First,using the COMSOL software,a suitablemechanicalmodel was created in accordance with the geological structure and project characteristics of the underground reservoir.Next,the characteristics of the stress field,displacement field,and seepage field after excavation of the underground reservoir were simulated in light of the seepage effect of groundwater on the nearby rock of the underground reservoir.Finally,based on the construction specifications and Molar-Coulomb criterion,a thorough evaluation of the stability of the underground reservoir was performed through simulation of the filling and discharge conditions and anti-seepage strengthening measures.The findings demonstrate that the numerical simulation results have a certain level of reliability and are in accordance with the stress measured in the project area.The underground reservoir excavation resulted in a maximum displacement value of the rock mass around the caverns of 3.56 mm in a typical section,and the safety coefficient of the parts,as determined using the Molar-Coulomb criterion,was higher than 1,indicating that the project as a whole is in a stable state.展开更多
High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO_(4) laser with a MgO-doped periodically-poled LiNbO_(3)(MgO:PPLN)crystal at room temperature.An average pow...High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO_(4) laser with a MgO-doped periodically-poled LiNbO_(3)(MgO:PPLN)crystal at room temperature.An average power of 2.4 W at 0.53μm is obtained under the pump 15 W at 808 nm,corresponding to an overall optical-to-optical conversion efficiency of 16%.The M^(2) factor of the green beam is 3.90 and 1.34 for the horizontal and vertical direction,respectively.In addition,the power fluctuation is measured to be about±5%.展开更多
Using a plane–plane resonator composed of silicon carbide mirrors,we achieve for the first time multi-pass amplification of a 46.9 nm laser pumped by capillary discharge.In terms of the temporal characteristics,for a...Using a plane–plane resonator composed of silicon carbide mirrors,we achieve for the first time multi-pass amplification of a 46.9 nm laser pumped by capillary discharge.In terms of the temporal characteristics,for an initial argon pressure of 17 Pa,triple-pass amplification of the laser is obtained at a delay time between the pre-pulse and the main pulse currents of 40s,and quadruple-pass amplification is obtained at a delay time of 50s.The experimental results show that the gain duration of the plasma column is more than 6 ns.In terms of spatial characteristics,the spot of the output laser has a reduced full width at half maximum divergence compared with that from a laser without a resonator.展开更多
The conversion-efficiency for second-harmonic(SH)in optical fibers is significantly limited by extremely weak second-order nonlinearity of fused silica,and pulse pump lasers with high peak power are widely employed.He...The conversion-efficiency for second-harmonic(SH)in optical fibers is significantly limited by extremely weak second-order nonlinearity of fused silica,and pulse pump lasers with high peak power are widely employed.Here,we propose a simple strategy to efficiently realize the broadband and continuous wave(CW)pumped SH,by transferring a crystalline GaSe coating onto a microfiber with phase-matching diameter.In the experiment,high efficiency up to 0.08%W-1mm-1 is reached for a C-band pump laser.The high enough efficiency not only guarantees SH at a single frequency pumped by a CW laser,but also multi-frequencies mixing supported by three CW light sources.Moreover,broadband SH spectrum is also achieved under the pump of a superluminescent light-emitting diode source with a 79.3 nm bandwidth.The proposed scheme provides a beneficial method to the enhancement of various nonlinear parameter processes,development of quasi-monochromatic or broadband CW light sources at new wavelength regions.展开更多
Inflammatory bowel disease(IBD)is believed to be caused by various factors,including abnormalities in disease susceptibility genes,environmental factors,immune factors,and intestinal bacteria.Proton pump inhibitors(PP...Inflammatory bowel disease(IBD)is believed to be caused by various factors,including abnormalities in disease susceptibility genes,environmental factors,immune factors,and intestinal bacteria.Proton pump inhibitors(PPIs)are the primary drugs used to treat acid-related diseases.They are also commonly prescribed to patients with IBD.Recent studies have suggested a potential association between the use of certain medications,such as PPIs,and the occurrence and progression of IBD.In this review,we summarize the potential impact of PPIs on IBD and analyze the underlying mechanisms.Our findings may provide insights for conducting further investigations into the effects of PPIs on IBD and serve as an important reminder for physicians to exercise caution when prescribing PPIs to patients with IBD.展开更多
As an emerging technology to convert environmental high-entropy energy into electrical energy,triboelectric nanogenerator(TENG)has great demands for further enhancing the service lifetime and output performance in pra...As an emerging technology to convert environmental high-entropy energy into electrical energy,triboelectric nanogenerator(TENG)has great demands for further enhancing the service lifetime and output performance in practical applications.Here,an ultra-robust and high-performance rotational triboelectric nanogenerator(R-TENG)by bearing charge pumping is proposed.The R-TENG composes of a pumping TENG(P-TENG),an output TENG(O-TENG),a voltage-multiplying circuit(VMC),and a buffer capacitor.The P-TENG is designed with freestanding mode based on a rolling ball bearing,which can also act as the rotating mechanical energy harvester.The output low charge from the P-TENG is accumulated and pumped to the non-contact O-TENG,which can simultaneously realize ultralow mechanical wear and high output performance.The matched instantaneous power of R-TENG is increased by 32 times under 300 r/min.Furthermore,the transferring charge of R-TENG can remain 95%during 15 days(6.4×10^(6)cycles)continuous operation.This work presents a realizable method to further enhance the durability of TENG,which would facilitate the practical applications of high-performance TENG in harvesting distributed ambient micro mechanical energy.展开更多
In this paper,an NMOS output-capacitorless low-dropout regulator(OCL-LDO)featuring dual-loop regulation has been proposed,achieving fast transient response with low power consumption.An event-driven charge pump(CP)loo...In this paper,an NMOS output-capacitorless low-dropout regulator(OCL-LDO)featuring dual-loop regulation has been proposed,achieving fast transient response with low power consumption.An event-driven charge pump(CP)loop with the dynamic strength control(DSC),is proposed in this paper,which overcomes trade-offs inherent in conventional structures.The presented design addresses and resolves the large signal stability issue,which has been previously overlooked in the event-driven charge pump structure.This breakthrough allows for the full exploitation of the charge-pump structure's poten-tial,particularly in enhancing transient recovery.Moreover,a dynamic error amplifier is utilized to attain precise regulation of the steady-state output voltage,leading to favorable static characteristics.A prototype chip has been fabricated in 65 nm CMOS technology.The measurement results show that the proposed OCL-LDO achieves a 410 nA low quiescent current(IQ)and can recover within 30 ns under 200 mA/10 ns loading change.展开更多
Dynamically tunable laser sources are highly promising for realizing visionary concepts of integrated photonic circuits and other applications. In this paper, a Ga N-based laser with an integrated PN junction heater o...Dynamically tunable laser sources are highly promising for realizing visionary concepts of integrated photonic circuits and other applications. In this paper, a Ga N-based laser with an integrated PN junction heater on Si is fabricated.The photoluminescence properties of the Ga N beam cavity are controlled by temperature, and the Joule heater provides electrically driven regulation of temperature. These two features of the cavity make it possible to realize convenient tuning of the lasing properties. The multi-functional Ga N beam cavity achieves optically pumped lasing with a single mode near 362.4 nm with a high Q-factor of 1394. The temperature of this device increases by 0–5℃ under the Joule heating effect. Then, electrical control of the lasing mode is demonstrated. The lasing resonant peak shows a continuous redshift of about 0.5 nm and the device also exhibits dynamic switching of its lasing mode. The lasing modulation can be ascribed to temperature-induced reduction of the bandgap. Our work may be of benefit for external optical modulation in future chip-based optoelectronic devices.展开更多
The integration of solar and wind energy into the electrical grid has received global research attention due to their unpredictable characteristics.Because wind energy varies across all timescales of utility activity,...The integration of solar and wind energy into the electrical grid has received global research attention due to their unpredictable characteristics.Because wind energy varies across all timescales of utility activity,renewable energy generation should be supplemented and enhanced,from real-time,minute-to-minute variations to annual alterations influencing long-termstrategy.Wind energy generation does not only fluctuate but is also challenging to accurately forecast the timeframes of significance to electricity decision makers;day-ahead and long-term making plans of framework sufficiency such as meeting the network peak load annually.A utility that integrates wind and solar energy into its electricity mix would understand how to adapt to uncertainty and variability in operations while sustaining grid stability.Due to hydropower’s adaptability,a system using hydropower as one of its generating resources could be precisely adapted to absorb the variability of wind and solar energy.The objective of this research study is to create a hybrid system comprising hydro-wind and solar(Hybrid-HWS)integration for power balancing in an isolated electrical network in Klipkop village,Pretoria region,South Africa.The desirability of designing and building goaf storage tank in regard to capability,the fullness of line throughoutwater pumping,dispensing,storage tank spillage,and pressure difference throughout liquid flow within the storage tanks were preliminary assessed using geotechnical and weather forecasting data from a distinctive area of Klipkop town in Pretoria,South Africa.Different facility hours premised on daylight accessibility are scheduled to balance maximum load at early and late hours.However,in the scenario of electrical power,time shift requiring storage for extended periods of time,such as in terms of hours,Hybrid-HWS has been found to have a crucial role.The results of simulations showed a coordinated process design for Hybrid-HWS Energy Storage(ES)to determine everyday strategic planning in reducing the variability of the system resulting from wind-solar-pumped hydro ES output inadequacies and satisfy daily load demands.It could be recommended that by considering the adaptability characteristics,extremely rapidly,ramping,peaking support and maximum stabilizing aid of the system could be archived with pump-hydro into the energy mix which can provide specific guidelines for energy policymakers.展开更多
This contribution presents a novel wear dependent virtual flow rate sensor for single stage single lobe progressing cavity pumps. We study the wear-induced material loss of the pump components and the impact of this m...This contribution presents a novel wear dependent virtual flow rate sensor for single stage single lobe progressing cavity pumps. We study the wear-induced material loss of the pump components and the impact of this material loss on the volumetric efficiency. The results are combined with an established backflow model to implement a backflow calculation procedure that is adaptive to wear. We use a laboratory test setup with a highly abrasive fluid and operate a pump from new to worn condition to validate our approach. The obtained measurement data show that the presented virtual sensor is capable of calculating the flow rate of a pump being subject to wear during its regular operation.展开更多
In order to obtain the transient characteristics of a low-speed centrifugal pump during the start-up and shutdown stages,dedicated experimental tests were conducted with eight different valve opening conditions.The Pe...In order to obtain the transient characteristics of a low-speed centrifugal pump during the start-up and shutdown stages,dedicated experimental tests were conducted with eight different valve opening conditions.The Pearson correlation coefficient was used to reveal the linear correlation between variables.According to the results,the stable rotational speed decreases with increasing valve opening(rotational speed decreases from approximately 1472 to 1453 r/min),while the stable shaft power exhibits an increasing trend(shaft power increases from approximately 0.242 to 0.390 kW).The stable time and zeroing time of each parameter during start-up and shutdown processes vary,with the flow zeroing time significantly increasing with the relative flow,reaching up to 10.468 s,while the shaft power zeroing time is roughly between 1.219 and 1.375 s.The results demonstrate that with increasing valve opening,the stable and zeroing time of flow significantly increase(|r|greater than 0.95),while the stable and zeroing time of rotational speed,power,and head display a smaller sensitivity on the valve opening(|r|less than 0.6).展开更多
The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generationand transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structur...The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generationand transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structures, the two ferromagneticlayers demonstrate in-phase and out-of-phase states, corresponding to acoustic and optical precession modes. Withinthis context, our study explores the spin pumping effect in Py/Ru/Py synthetic antiferromagnetic structures across differentmodes. The heightened magnetic damping resulting from the spin pumping effect in the in-phase state initially decreaseswith increasing Py thickness before stabilizing. Conversely, in the out-of-phase state, the amplified damping exceeds thatof the in-phase state, suggesting a greater spin relaxation within this configuration, which demonstrates sensitivity to alterationsin static exchange interactions. These findings contribute to advancing the application of synthetic antiferromagneticstructures in magnonic devices.展开更多
Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow pulsation.It is one of the main hazards that affect the regular operation of ...Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow pulsation.It is one of the main hazards that affect the regular operation of the pump.Research on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,etc.However,there are few cavitation studies on external herringbone gear pumps.In addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow field.Therefore,it is urgent to study the cavitation characteristics of external herringbone gear pumps.Compared with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is easier.The simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing area.Cavitation can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be achieved.For example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.展开更多
BACKGROUND Gastro-esophageal reflux disease(GERD)may affect the upper digestive tract;up to 20%of population in Western nations are affected by GERD.Antacids,histamine H2-receptor antagonists,and Proton Pump Inhibitor...BACKGROUND Gastro-esophageal reflux disease(GERD)may affect the upper digestive tract;up to 20%of population in Western nations are affected by GERD.Antacids,histamine H2-receptor antagonists,and Proton Pump Inhibitors(PPIs)are considered the referring medications for GERD.Nevertheless,PPIs must be managed carefully because their use,especially chronic,could be linked with some adverse effects.An effective and safe alternative pharmacological tool for GERD is needed.After the identification of potentially new medications to flank PPIs,it is mandatory to revise and improve good clinical practices even through a consensus process.AIM To optimize diagnosis and treatment guidelines for GERD through a consensus based on Delphi method.METHODS The availability of clinical studies describing the action of the multicomponent/multitarget medication Nux vomica-Heel,subject of the consensus,is the basic prerequisite for the consensus itself.A modified Delphi process was used to reach a consensus among a panel of Italian GERD specialists on the overlapping approach PPIs/Nux vomica-Heel as a new intervention model for the management of GERD.The Voting Consensus group was composed of 49 Italian Medical Doctors with different specializations:Gastroenterology,otolaryngology,geriatrics,and general medicine.A scientific committee analyzed the literature,determined areas that required investigation(in agreement with the multiple-choice questionnaire results),and identified two topics of interest:(1)GERD disease;and(2)GERD treatment.Statements for each of these topics were then formulated and validated.The Delphi process involved two rounds of questioning submitted to the panel experts using an online platform.RESULTS According to their routinary GERD practice and current clinical evidence,the panel members provided feedback to each questionnaire statement.The experts evaluated 15 statements and reached consensus on all 15.The statements regarding the GERD disease showed high levels of agreement,with consensus ranging from 70%to 92%.The statements regarding the GERD treatment also showed very high levels of agreement,with consensus ranging from 90%to 100%.This Delphi process was able to reach consensus among physicians in relevant aspects of GERD management,such as the adoption of a new approach to treat patients with GERD based on the overlapping between PPIs and Nux vomica-Heel.The consensus was unanimous among the physicians with different specializations,underlying the uniqueness of the agreement reached to identify in the overlapping approach between PPIs and Nux vomica-Heel a new intervention model for GERD management.The results support that an effective approach to deprescribe PPIs through a progressive decalage timetable(reducing PPIs administration to as-needed use),should be considered.CONCLUSION Nux vomica-Heel appears to be a valid opportunity for GERD treatment to favor the deprescription of PPIs and to maintain low disease activity together with the symptomatology remission.展开更多
文摘China has embarked on an extensive and sustained endeavor to harness its coal resources for a substantial period.However,the depletion of coal reserves in mining regions has necessitated the closure or abandonment of numerous mines,resulting in a marked increase in the number of such facilities.Parallel to this,China is vigorously advancing the development of a novel energy power system,aimed at transitioning the power sector from a high-carbon,fossil fuel-dependent paradigm to a low-carbon,clean energy footing.
基金Nanjing University of Posts and Telecommunications Foundation(Grant Nos.JUH219002 and JUH219007)Key Laboratory of Functional Crystals and Laser Technology,TIPC,CAS Foundation(Grant No.FCLT 202201)。
文摘We report a high-average-power acousto-optic(AO)Q-switched intracavity frequency-doubled red laser based on a high-efficiency light-emitting-diode(LED)pumped two-rod Nd,Ce:YAG laser module.Under quasi-continuous wave operation conditions,a maximum output power of 1319.08 nm wavelength was achieved at 11.26 W at a repetition rate of 100 Hz.
基金Project supported by the National Natural Science Foundation of China(NSFC)(Grant No.12004309)the Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.22JSQ036)the Scientific Research Program funded by Shaanxi Provincial Education Department(Grant No.20JK0947).
文摘We show that the nonlinear stage of the dual-wavelength pumped modulation instability(MI)in nonlinear Schrödinger equation(NLSE)can be effectively analyzed by mode truncation methods.The resulting complicated heteroclinic structure of instability unveils all possible dynamic trajectories of nonlinear waves.Significantly,the latticed-Fermi-Pasta-Ulam recurrences on the modulated-wave background in NLSE are also investigated and their dynamic trajectories run along the Hamiltonian contours of the heteroclinic structure.It is demonstrated that there has much richer dynamic behavior,in contrast to the nonlinear waves reported before.This novel nonlinear wave promises to inject new vitality into the study of MI.
基金Project(52204101)supported by the National Natural Science Foundation of ChinaProject(ZR2022QE137)supported by the Natural Science Foundation of Shandong Province,ChinaProject(SKLGDUEK2023)supported by the Open Project of State Key Laboratory for Geomechanics and Deep Underground Engineering in China University of Mining&Technology,Beijing,China。
文摘During the construction and operation of the abandoned mine pumped storage power station,the underground space surrounding rock body faces the complex stress environment under the action of mining disturbance,frequent pumping,water storage and other dynamic disturbances.The stability of the abandoned mine surrounding rock body is the basis for guaranteeing the safety and effectiveness of water storage in the underground space of the abandoned mine.By considering the two main factors of different stress levels and disturbance amplitudes,the mechanical properties,damage characteristics and acoustic emission characteristics of the abandoned mine perimeter rock body under dynamic disturbance were investigated using a creep-disturbed dynamic impact loading system.The experimental results show that:1)The stress level is considered to be the major contributing factor of the failure of muddy sandstone,followed by the amplitude of the disturbances;2)The time required for the destruction of muddy sandstone decreases with the increase of amplitude.When the stress level is 80%,the sandstone specimens have a decreasing number of cycles as the disturbance amplitude increases.The disturbance amplitude is sequentially increased from 4 MPa to 5,6,7,and 8 MPa,the number of cycles required for specimen destruction decreases significantly by 96.71%,99.13%,99.60%,and 99.93%,respectively;3)Disturbance amplitude and stress level have a significant effect on muddy sandstone damage and damage occurs only after a certain threshold is reached.With the increase of stress level and disturbance amplitude,the macroscopic damage of muddy sandstone is mainly conical,with obvious flake spalling and poor damage integrity;4)According to the time-dependent changes in AE energy and ringing counts,the acoustic emission activity during the failure process could be divided into three phases,namely,weakening period,smooth period,and surge period,corresponding to the compaction phase,elastic rise phase and post-peak damage phase.The research results are of reference significance for the damage evolution analysis of muddy sandstone under dynamic disturbance and the safety and stability of abandoned mine perimeter rock body.
基金Project(202208340045)supported by the China Scholarship Council FundProject(U21A20110)supported by the Regional Innovation and Development Joint Fund of National Natural Science Foundation of China+1 种基金Project(EUCMR202201)supported by the Open Project Program of Anhui Engineering Research Center of Exploitation and Utilization of Closed/abandoned Mine Resources,ChinaProject(2023cxcyzx063)supported by the Anhui Province New Era Talent Education Project,China。
文摘Within the framework of achieving carbon neutrality,various industries are confronted with fresh challenges.The ongoing process of downsizing coal industry operations has evolved into a new phase,with the burgeoning proliferation of abandoned mines posing a persistent issue.Addressing the challenges and opportunities presented by these abandoned mines,this paper advocates for a scientific approach centered on the advancement of pumped storage energy alongside gas-oil complementary energy.Leveraging abandoned mine tunnels to establish pumped storage power stations holds significant ecological and economic importance for repurposing these sites.This initiative not only serves as an effective means to restore the ecological balance in mining regions but also provides an environmentally friendly approach to repurposing abandoned mine tunnels,offering a blueprint for economically viable pumped storage power stations.This article delineates five crucial scientific considerations and outlines seven primary models for the utilization of abandoned mine sites,delineating a novel,comprehensive pathway for energy and power development that emphasizes multi-energy complementarity and synergistic optimization within abandoned mines.
基金Project(8212033)supported by the Natural Science Foundation of Beijing,ChinaProject(BBJ2023051)supported by the Fundamental Research Funds of China University of Mining and Technology-BeijingProject(SKLGDUEK202221)supported by the Innovation Fund Research Project,China。
文摘Every year in China,a significant number of mines are closed or abandoned.The pumped hydroelectric storage(PHS)and geothermal utilization are vital means to efficiently repurpose resources in abandoned mine.In this work,the development potentials of the PHS and geothermal utilization systems were evaluated.Considering the geological conditions and meteorological data available of Jiahe abandoned mine,a simple evaluation model for PHS and geothermal utilization was established.The average efficiency of the PHS system exceeds 70%and the regulatable energy of a unit volume is over 1.53 kW·h/m^(3).The PHS system achieves optimal performance when the wind/solar power ratio reaches 0.6 and 0.3 in daily and year scale,respectively.In the geothermal utilization system,the outlet temperature and heat production are significantly affected by the injection flow rate.The heat production performance is more stable at lower rate flow,and the proportion of heat production is higher in the initial stage at greater flow rate.As the operating time increases,the proportion of heat production gradually decreases.The cyclic heat storage status has obvious advantages in heat generation and cooling.Furthermore,the energy-saving and emission reduction benefits of PHS and geothermal utilization systems were calculated.
基金funded by the BeijingNatural Science Foundation of China(8222003)National Natural Science Foundation of China(41807180).
文摘Based on global initiatives such as the clean energy transition and the development of renewable energy,the pumped storage power station has become a new and significant way of energy storage and regulation,and its construction environment is more complex than that of a traditional reservoir.In particular,the stability of the rock strata in the underground reservoirs is affected by the seepage pressure and rock stress,which presents some challenges in achieving engineering safety and stability.Using the advantages of the numerical simulation method in dealing deal with nonlinear problems in engineering stability,in this study,the stability of the underground reservoir of the Shidangshan(SDS)pumped storage power station was numerically calculated and quantitatively analyzed based on fluid-structure coupling theory,providing an important reference for the safe operation and management of the underground reservoir.First,using the COMSOL software,a suitablemechanicalmodel was created in accordance with the geological structure and project characteristics of the underground reservoir.Next,the characteristics of the stress field,displacement field,and seepage field after excavation of the underground reservoir were simulated in light of the seepage effect of groundwater on the nearby rock of the underground reservoir.Finally,based on the construction specifications and Molar-Coulomb criterion,a thorough evaluation of the stability of the underground reservoir was performed through simulation of the filling and discharge conditions and anti-seepage strengthening measures.The findings demonstrate that the numerical simulation results have a certain level of reliability and are in accordance with the stress measured in the project area.The underground reservoir excavation resulted in a maximum displacement value of the rock mass around the caverns of 3.56 mm in a typical section,and the safety coefficient of the parts,as determined using the Molar-Coulomb criterion,was higher than 1,indicating that the project as a whole is in a stable state.
基金Supported by the Jiangsu Science Foundation(BK2011545)the Chinese State Key Program for Basic Research(Nos 2010CB630703 and 2011CBA00205)+1 种基金the National Natural Science Foundation of China(No 11021403)the PAPD.
文摘High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO_(4) laser with a MgO-doped periodically-poled LiNbO_(3)(MgO:PPLN)crystal at room temperature.An average power of 2.4 W at 0.53μm is obtained under the pump 15 W at 808 nm,corresponding to an overall optical-to-optical conversion efficiency of 16%.The M^(2) factor of the green beam is 3.90 and 1.34 for the horizontal and vertical direction,respectively.In addition,the power fluctuation is measured to be about±5%.
基金funded by the National Natural Science Foundation of China(Grant Nos.61875045 and 62005066).
文摘Using a plane–plane resonator composed of silicon carbide mirrors,we achieve for the first time multi-pass amplification of a 46.9 nm laser pumped by capillary discharge.In terms of the temporal characteristics,for an initial argon pressure of 17 Pa,triple-pass amplification of the laser is obtained at a delay time between the pre-pulse and the main pulse currents of 40s,and quadruple-pass amplification is obtained at a delay time of 50s.The experimental results show that the gain duration of the plasma column is more than 6 ns.In terms of spatial characteristics,the spot of the output laser has a reduced full width at half maximum divergence compared with that from a laser without a resonator.
基金supports from National Natural Science Foundation of China(No.61975166,11634010)Key Research and Development Program(No.2017YFA0303800).
文摘The conversion-efficiency for second-harmonic(SH)in optical fibers is significantly limited by extremely weak second-order nonlinearity of fused silica,and pulse pump lasers with high peak power are widely employed.Here,we propose a simple strategy to efficiently realize the broadband and continuous wave(CW)pumped SH,by transferring a crystalline GaSe coating onto a microfiber with phase-matching diameter.In the experiment,high efficiency up to 0.08%W-1mm-1 is reached for a C-band pump laser.The high enough efficiency not only guarantees SH at a single frequency pumped by a CW laser,but also multi-frequencies mixing supported by three CW light sources.Moreover,broadband SH spectrum is also achieved under the pump of a superluminescent light-emitting diode source with a 79.3 nm bandwidth.The proposed scheme provides a beneficial method to the enhancement of various nonlinear parameter processes,development of quasi-monochromatic or broadband CW light sources at new wavelength regions.
文摘Inflammatory bowel disease(IBD)is believed to be caused by various factors,including abnormalities in disease susceptibility genes,environmental factors,immune factors,and intestinal bacteria.Proton pump inhibitors(PPIs)are the primary drugs used to treat acid-related diseases.They are also commonly prescribed to patients with IBD.Recent studies have suggested a potential association between the use of certain medications,such as PPIs,and the occurrence and progression of IBD.In this review,we summarize the potential impact of PPIs on IBD and analyze the underlying mechanisms.Our findings may provide insights for conducting further investigations into the effects of PPIs on IBD and serve as an important reminder for physicians to exercise caution when prescribing PPIs to patients with IBD.
基金supported by the National Natural Science Foundation of China(Nos.51922023,61874011)Fundamental Research Funds for the Central Universities(E1EG6804)
文摘As an emerging technology to convert environmental high-entropy energy into electrical energy,triboelectric nanogenerator(TENG)has great demands for further enhancing the service lifetime and output performance in practical applications.Here,an ultra-robust and high-performance rotational triboelectric nanogenerator(R-TENG)by bearing charge pumping is proposed.The R-TENG composes of a pumping TENG(P-TENG),an output TENG(O-TENG),a voltage-multiplying circuit(VMC),and a buffer capacitor.The P-TENG is designed with freestanding mode based on a rolling ball bearing,which can also act as the rotating mechanical energy harvester.The output low charge from the P-TENG is accumulated and pumped to the non-contact O-TENG,which can simultaneously realize ultralow mechanical wear and high output performance.The matched instantaneous power of R-TENG is increased by 32 times under 300 r/min.Furthermore,the transferring charge of R-TENG can remain 95%during 15 days(6.4×10^(6)cycles)continuous operation.This work presents a realizable method to further enhance the durability of TENG,which would facilitate the practical applications of high-performance TENG in harvesting distributed ambient micro mechanical energy.
基金supported by the National Natural Science Foundation of China under Grant 62274189the Natural Science Foundation of Guangdong Province,China,under Grant 2022A1515011054the Key Area R&D Program of Guangdong Province under Grant 2022B0701180001.
文摘In this paper,an NMOS output-capacitorless low-dropout regulator(OCL-LDO)featuring dual-loop regulation has been proposed,achieving fast transient response with low power consumption.An event-driven charge pump(CP)loop with the dynamic strength control(DSC),is proposed in this paper,which overcomes trade-offs inherent in conventional structures.The presented design addresses and resolves the large signal stability issue,which has been previously overlooked in the event-driven charge pump structure.This breakthrough allows for the full exploitation of the charge-pump structure's poten-tial,particularly in enhancing transient recovery.Moreover,a dynamic error amplifier is utilized to attain precise regulation of the steady-state output voltage,leading to favorable static characteristics.A prototype chip has been fabricated in 65 nm CMOS technology.The measurement results show that the proposed OCL-LDO achieves a 410 nA low quiescent current(IQ)and can recover within 30 ns under 200 mA/10 ns loading change.
基金the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20210593)the Foundation of Jiangsu Provincial Double Innovation Doctor Program (Grant No. 30644)+2 种基金the National Natural Science Foundation of China (Grant No. 62204127)State Key Laboratory of Luminescence and Applications (Grant No. SKLA 202104)open research fund of Key Lab of Broadband Wireless Communication and Sensor Network Technology (Nanjing University of Posts and Telecommunications, Ministry of Education)。
文摘Dynamically tunable laser sources are highly promising for realizing visionary concepts of integrated photonic circuits and other applications. In this paper, a Ga N-based laser with an integrated PN junction heater on Si is fabricated.The photoluminescence properties of the Ga N beam cavity are controlled by temperature, and the Joule heater provides electrically driven regulation of temperature. These two features of the cavity make it possible to realize convenient tuning of the lasing properties. The multi-functional Ga N beam cavity achieves optically pumped lasing with a single mode near 362.4 nm with a high Q-factor of 1394. The temperature of this device increases by 0–5℃ under the Joule heating effect. Then, electrical control of the lasing mode is demonstrated. The lasing resonant peak shows a continuous redshift of about 0.5 nm and the device also exhibits dynamic switching of its lasing mode. The lasing modulation can be ascribed to temperature-induced reduction of the bandgap. Our work may be of benefit for external optical modulation in future chip-based optoelectronic devices.
基金This study was supported by the DUT Scholarship Scheme Masters:2022(RFA Smart Grid)Funding.
文摘The integration of solar and wind energy into the electrical grid has received global research attention due to their unpredictable characteristics.Because wind energy varies across all timescales of utility activity,renewable energy generation should be supplemented and enhanced,from real-time,minute-to-minute variations to annual alterations influencing long-termstrategy.Wind energy generation does not only fluctuate but is also challenging to accurately forecast the timeframes of significance to electricity decision makers;day-ahead and long-term making plans of framework sufficiency such as meeting the network peak load annually.A utility that integrates wind and solar energy into its electricity mix would understand how to adapt to uncertainty and variability in operations while sustaining grid stability.Due to hydropower’s adaptability,a system using hydropower as one of its generating resources could be precisely adapted to absorb the variability of wind and solar energy.The objective of this research study is to create a hybrid system comprising hydro-wind and solar(Hybrid-HWS)integration for power balancing in an isolated electrical network in Klipkop village,Pretoria region,South Africa.The desirability of designing and building goaf storage tank in regard to capability,the fullness of line throughoutwater pumping,dispensing,storage tank spillage,and pressure difference throughout liquid flow within the storage tanks were preliminary assessed using geotechnical and weather forecasting data from a distinctive area of Klipkop town in Pretoria,South Africa.Different facility hours premised on daylight accessibility are scheduled to balance maximum load at early and late hours.However,in the scenario of electrical power,time shift requiring storage for extended periods of time,such as in terms of hours,Hybrid-HWS has been found to have a crucial role.The results of simulations showed a coordinated process design for Hybrid-HWS Energy Storage(ES)to determine everyday strategic planning in reducing the variability of the system resulting from wind-solar-pumped hydro ES output inadequacies and satisfy daily load demands.It could be recommended that by considering the adaptability characteristics,extremely rapidly,ramping,peaking support and maximum stabilizing aid of the system could be archived with pump-hydro into the energy mix which can provide specific guidelines for energy policymakers.
基金Funding by Ministerium für Wirtschaft,Innovation,Digitalisierung und Energie des Landes Nordrhein-Westfalen。
文摘This contribution presents a novel wear dependent virtual flow rate sensor for single stage single lobe progressing cavity pumps. We study the wear-induced material loss of the pump components and the impact of this material loss on the volumetric efficiency. The results are combined with an established backflow model to implement a backflow calculation procedure that is adaptive to wear. We use a laboratory test setup with a highly abrasive fluid and operate a pump from new to worn condition to validate our approach. The obtained measurement data show that the presented virtual sensor is capable of calculating the flow rate of a pump being subject to wear during its regular operation.
基金supported by Science and Technology Project of Quzhou(Grant Nos.2023K256,2023NC08)Zhejiang Provincial Natural Science Foundation of China(Grant No.LZY21E050001)Hunan Province Key Field R&D Plan Project(Grant No.2022GK2068).
文摘In order to obtain the transient characteristics of a low-speed centrifugal pump during the start-up and shutdown stages,dedicated experimental tests were conducted with eight different valve opening conditions.The Pearson correlation coefficient was used to reveal the linear correlation between variables.According to the results,the stable rotational speed decreases with increasing valve opening(rotational speed decreases from approximately 1472 to 1453 r/min),while the stable shaft power exhibits an increasing trend(shaft power increases from approximately 0.242 to 0.390 kW).The stable time and zeroing time of each parameter during start-up and shutdown processes vary,with the flow zeroing time significantly increasing with the relative flow,reaching up to 10.468 s,while the shaft power zeroing time is roughly between 1.219 and 1.375 s.The results demonstrate that with increasing valve opening,the stable and zeroing time of flow significantly increase(|r|greater than 0.95),while the stable and zeroing time of rotational speed,power,and head display a smaller sensitivity on the valve opening(|r|less than 0.6).
基金National Key Research and De-velopment Program of China(Grant No.2023YFA1406603)the National Natural Science Foundation of China(Grant Nos.52071079,12274071,12374112,and T2394473)Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2023ZB491).
文摘The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generationand transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structures, the two ferromagneticlayers demonstrate in-phase and out-of-phase states, corresponding to acoustic and optical precession modes. Withinthis context, our study explores the spin pumping effect in Py/Ru/Py synthetic antiferromagnetic structures across differentmodes. The heightened magnetic damping resulting from the spin pumping effect in the in-phase state initially decreaseswith increasing Py thickness before stabilizing. Conversely, in the out-of-phase state, the amplified damping exceeds thatof the in-phase state, suggesting a greater spin relaxation within this configuration, which demonstrates sensitivity to alterationsin static exchange interactions. These findings contribute to advancing the application of synthetic antiferromagneticstructures in magnonic devices.
基金supported by a Grant(2024-MOIS35-005)of Policy-linked Technology Development Program on Natural Disaster Prevention and Mitigation funded by Ministry of Interior and Safety(MOIS,Korea).
文摘Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow pulsation.It is one of the main hazards that affect the regular operation of the pump.Research on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,etc.However,there are few cavitation studies on external herringbone gear pumps.In addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow field.Therefore,it is urgent to study the cavitation characteristics of external herringbone gear pumps.Compared with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is easier.The simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing area.Cavitation can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be achieved.For example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.
文摘BACKGROUND Gastro-esophageal reflux disease(GERD)may affect the upper digestive tract;up to 20%of population in Western nations are affected by GERD.Antacids,histamine H2-receptor antagonists,and Proton Pump Inhibitors(PPIs)are considered the referring medications for GERD.Nevertheless,PPIs must be managed carefully because their use,especially chronic,could be linked with some adverse effects.An effective and safe alternative pharmacological tool for GERD is needed.After the identification of potentially new medications to flank PPIs,it is mandatory to revise and improve good clinical practices even through a consensus process.AIM To optimize diagnosis and treatment guidelines for GERD through a consensus based on Delphi method.METHODS The availability of clinical studies describing the action of the multicomponent/multitarget medication Nux vomica-Heel,subject of the consensus,is the basic prerequisite for the consensus itself.A modified Delphi process was used to reach a consensus among a panel of Italian GERD specialists on the overlapping approach PPIs/Nux vomica-Heel as a new intervention model for the management of GERD.The Voting Consensus group was composed of 49 Italian Medical Doctors with different specializations:Gastroenterology,otolaryngology,geriatrics,and general medicine.A scientific committee analyzed the literature,determined areas that required investigation(in agreement with the multiple-choice questionnaire results),and identified two topics of interest:(1)GERD disease;and(2)GERD treatment.Statements for each of these topics were then formulated and validated.The Delphi process involved two rounds of questioning submitted to the panel experts using an online platform.RESULTS According to their routinary GERD practice and current clinical evidence,the panel members provided feedback to each questionnaire statement.The experts evaluated 15 statements and reached consensus on all 15.The statements regarding the GERD disease showed high levels of agreement,with consensus ranging from 70%to 92%.The statements regarding the GERD treatment also showed very high levels of agreement,with consensus ranging from 90%to 100%.This Delphi process was able to reach consensus among physicians in relevant aspects of GERD management,such as the adoption of a new approach to treat patients with GERD based on the overlapping between PPIs and Nux vomica-Heel.The consensus was unanimous among the physicians with different specializations,underlying the uniqueness of the agreement reached to identify in the overlapping approach between PPIs and Nux vomica-Heel a new intervention model for GERD management.The results support that an effective approach to deprescribe PPIs through a progressive decalage timetable(reducing PPIs administration to as-needed use),should be considered.CONCLUSION Nux vomica-Heel appears to be a valid opportunity for GERD treatment to favor the deprescription of PPIs and to maintain low disease activity together with the symptomatology remission.
