In this study, the vibrations of multiple stepped beams with cubic nonlinearities are considered. A three-to-one internal resonance case is investigated for the system. A general approximate solution to the problem is...In this study, the vibrations of multiple stepped beams with cubic nonlinearities are considered. A three-to-one internal resonance case is investigated for the system. A general approximate solution to the problem is found using the method of multiple scales （a perturbation technique）. The modulation equations of the amplitudes and the phases are derived for two modes. These equations are utilized to determine steady state solutions and their stabilities. It is assumed that the external forcing frequency is close to the lower frequency. For the numeric part of the study, the three-to-one ratio in natural frequencies is investigated. These values are observed to be between the first and second natural frequencies in the cases of the clamped-clamped and clamped-pinned supports, and between the second and third natural frequencies in the case of the pinned-pinned support. Finally, a numeric algorithm is used to solve the three-to-one internal resonance. The first mode is externally excited for the clamped-clamped and clamped-pinned supports, and the second mode is externally excited for the pinned-pinned support. Then, the amplitudes of the first and second modes are investigated when the first mode is externally excited. The amplitudes of the second and third modes are investigated when the second mode is externally excited. The force-response, damping-response, and .frequency- response curves are plotted for the internal resonance modes of vibrations. The stability analysis is carried out for these plots.展开更多
A grating lobes suppression method for chirp-subpulse stepped frequency（CSSF） signals is proposed, which is applied to deformation monitoring using the ground based synthetic aperture radar（GB-SAR） system. This me...A grating lobes suppression method for chirp-subpulse stepped frequency（CSSF） signals is proposed, which is applied to deformation monitoring using the ground based synthetic aperture radar（GB-SAR） system. This method is based on accurate estimation and correction of the phase and amplitude error along two dimensions（range and azimuth）, i.e., the error estimation inside the subpulse（in-subpulse error） and across the stepped frequency subpulses（cross-subpulse error） of transmitted CSSF signals. Validated both with simulated data and experimental data recorded in the deformation monitoring campaign, it can be seen that the method as well as the relative conclusions can be fully and effectively applied to most of the stepped frequency systems.展开更多
In this study, the influence of geometrical parameters on the curve veering phenomenon in a tor-sional system with stepped shaft is investigated. Three approximate solutions including finite el-ement, Rayleigh-Ritz an...In this study, the influence of geometrical parameters on the curve veering phenomenon in a tor-sional system with stepped shaft is investigated. Three approximate solutions including finite el-ement, Rayleigh-Ritz and discretization methods, along with an exact solution are employed to obtain the natural frequencies of the structure. The study reveals that, under specific circumstances, the results obtained by approximate methods are very close to the exact solution. The curve veering behavior is manifested irrespective of the method employed. It is concluded that for the structure studied the curve veering behavior is not because of the approximate techniques used to compute the natural frequencies, and is an inherent behavior of the structure.展开更多
Against the backdrop of China’s“dual-carbon”target,clean energy generation currently accounts for about 3.8 trillion kilowatt-hours,or 39.7 percent of total power generation,establishing a reasonable market trading...Against the backdrop of China’s“dual-carbon”target,clean energy generation currently accounts for about 3.8 trillion kilowatt-hours,or 39.7 percent of total power generation,establishing a reasonable market trading mechanism while enhancing the low-carbon economic benefits of the integrated energy system(IES)and optimizing the interests of various entities within the distribution system has become a significant challenge.Consequently,this paper proposes an optimization strategy for a low-carbon economy within a multi-agent IES that considers carbon capture systems(CCS)and power-to-gas(P2G).In this framework,the integrated energy system operator(IESO)acts as the primary leader,while energy suppliers(ES),energy storage operators(ESO),and load aggregators(LA)follow.At the level of low-carbon technology,a coupling model of P2G and CCS is developed,leading to the establishment of an IES that incorporates energy conversion and storage equipment.Economically,effective control of system carbon emissions in market trading is progressively established.Lastly,the trading decision model of the system is integrated within a master-slave game framework,utilizing an improved differential evolution algorithm in conjunction with the distributed equilibrium method of quadratic programming for solution.The calculation example demonstrates that the strategy safeguards the benefits for both parties in the game and achieves energy savings and carbon reduction for the system.展开更多
In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefo...In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.展开更多
This paper introduces the experience and practice in constructing the practical teaching system for the course“Electric Machine and Drive.”In response to the current status of cultivating innovative practical abilit...This paper introduces the experience and practice in constructing the practical teaching system for the course“Electric Machine and Drive.”In response to the current status of cultivating innovative practical abilities among electrical engineering majors,based on the independently developed virtual simulation experimental teaching platform for Electric Machine and Drive,a stepped practical teaching process consisting of“classroom teaching-experimental teaching-comprehensive training-scientific inquiry”has been elaborately designed.A hierarchical practical teaching model for the second classroom has also been established.With teaching objectives as the optimization index,the teaching content,methods and means have been optimized;the teaching process has been organized and implemented in the form of team collaboration,thus constructing a comprehensive,stepped,hierarchical,and closed-loop innovative practical teaching system.This achievement provides references and assistance for the practical teaching of the same or similar majors in other colleges and universities.展开更多
BACKGROUND Owing to age-related physiological declines,elderly patients undergoing radical gastrectomy(RG)often experience physical and psychological challenges.Hence,appropriate nursing strategies need to be identifi...BACKGROUND Owing to age-related physiological declines,elderly patients undergoing radical gastrectomy(RG)often experience physical and psychological challenges.Hence,appropriate nursing strategies need to be identified for optimizing patient outcomes.AIM To evaluate the effects of the Neuman Systems Model-guided stepped care intervention(NGSC)model on postoperative physical and psychological recovery in elderly patients with gastric cancer who underwent RG.METHODS In total,80 elderly patients(≥65 years old)who underwent RG at the Shanxi Fenyang Hospital between January 2023 and June 2024 were included and randomly divided as follows:Control group(n=40,those receiving conventional stepped care intervention);observation group(n=40,those receiving NGSC).Postoperative recovery indices,anxiety/depression scores(Self-Rating Anxiety Scale/Self-Rating Depression Scale),quality of life(36-item short form health survey),and adverse event rates were compared between the groups.RESULTS Compared with the control group,the observation group presented significantly shorter recovery times for first bowel sounds,ambulation,flatus,oral intake,catheter removal,and hospitalization(all P<0.05).Notably,in the observation group,Self-Rating Anxiety Scale/Self-Rating Depression Scale scores and the adverse event rate were significantly lower(all P<0.05),whereas 36-item short form health survey scores were higher(P<0.05),compared with those in the control group.CONCLUSION Overall,the findings of this study show that the proposed NGSC model accelerates postoperative recovery,alleviates psychological distress,improves quality of life,and reduces complications in elderly patients with gastric cancer who underwent RG,presenting potential for clinical application.展开更多
To address the issues of unclear carbon responsibility attribution,insufficient renewable energy absorption,and simplistic carbon trading mechanisms in integrated energy systems,this paper proposes an electricheat-hyd...To address the issues of unclear carbon responsibility attribution,insufficient renewable energy absorption,and simplistic carbon trading mechanisms in integrated energy systems,this paper proposes an electricheat-hydrogen integrated energy system(EHH-IES)optimal scheduling model considering carbon emission stream(CES)and wind-solar accommodation.First,the CES theory is introduced to quantify the carbon emission intensity of each energy conversion device and transmission branch by defining carbon emission rate,branch carbon intensity,and node carbon potential,realizing accurate tracking of carbon flow in the process of multi-energy coupling.Second,a stepped carbon pricing mechanism is established to dynamically adjust carbon trading costs based on the deviation between actual carbon emissions and initial quotas,strengthening the emission reduction incentive.Finally,a lowcarbon economic dispatch model is constructed with the objectives of minimizing operation cost,carbon trading cost,wind-solar curtailment penalty cost,and energy loss.Simulation results show that compared with the traditional economic dispatch scheme 3,the proposed schemel reduces carbon emissions by 53.97%and wind-solar curtailment by 68.89%with a 16.10%increase in total cost.This verifies that the model can effectively improve clean energy utilization and reduce carbon emissions,achieving low-carbon economic operation of EHH-IES,with CES theory ensuring precise carbon flow tracking across multi-energy links.展开更多
In the background of the low-carbon transformation of the energy structure,the problem of operational uncertainty caused by the high proportion of renewable energy sources and diverse loads in the integrated energy sy...In the background of the low-carbon transformation of the energy structure,the problem of operational uncertainty caused by the high proportion of renewable energy sources and diverse loads in the integrated energy systems(IES)is becoming increasingly obvious.In this case,to promote the low-carbon operation of IES and renewable energy consumption,and to improve the IES anti-interference ability,this paper proposes an IES scheduling strategy that considers CCS-P2G and concentrating solar power(CSP)station.Firstly,CSP station,gas hydrogen doping mode and variable hydrogen doping ratio mode are applied to IES,and combined with CCS-P2G coupling model,the IES low-carbon economic dispatch model is established.Secondly,the stepped carbon trading mechanism is applied,and the sensitivity analysis of IES carbon trading is carried out.Finally,an IES optimal scheduling strategy based on fuzzy opportunity constraints and an IES risk assessment strategy based on CVaR theory are established.The simulation shows that the gas-hydrogen doping model proposed in this paper reduces the operating cost and carbon emission of IES by 1.32%and 7.17%,and improves the carbon benefit by 5.73%;variable hydrogen doping ratio model reduces the operating cost and carbon emission of IES by 3.75%and 1.70%,respectively;CSP stations reduce 19.64%and 38.52%of the operating costs of IES and 1.03%and 1.80%of the carbon emissions of IES respectively compared to equal-capacity photovoltaic and wind turbines;the baseline price of carbon trading of IES and its rate of change jointly affect the carbon emissions of IES;evaluating the anti-interference capability of IES through trapezoidal fuzzy number and weighting coefficients,enabling IES to guarantee operation at the lowest cost.展开更多
Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtai...Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtain the HRR profile of a target. For moving targets which are of great importance in practical radar usage, autofocusing,i.e. phase correction, is a necessary and critical step of the synthetic HRR processing. The purpose of autofocusing is to remove the radial motion effect of the target from radar echoes, and only reserve the stepped frequency effect which is the basis of synthetic HRR capability. We investigate two autofocusing approaches for synthetic HRR radars using stepped frequency waveform in this paper. The first is motion fitting method. This method depends on a certain parametric model, and is computationally expensive. Then we propose the iterative dominant scatterer method. It is robust, non parametric and simple in computation in comparison with the motion fitting method. Experimental results based on data acquired by using a metallised scale model B 52 in a microwave anechoic chamber reveal the validity and effectiveness of the method.展开更多
An integrated system for assembly planning and design (INSAPS) is presented in which product data can be exchanged between assembly planning and assembly design on the basis of standard for exchange of product data mo...An integrated system for assembly planning and design (INSAPS) is presented in which product data can be exchanged between assembly planning and assembly design on the basis of standard for exchange of product data model (STEP). The system consists of CAD system, product modeling system, assembly planning system. The product model is organized according to the STEP, uses mostly the entities of IR (integrated resources) and partly self defined entities which is necessary for assembly planning. A simple method of assembly sequence generation is presented which is suitable for complex assembly planning. The generated assembly sequences are evaluated considering the optimization of total assembly time. The results of assembly planning are feedback to the stage of assembly design to improve design.展开更多
Aim To analyze dynamic failure of aerospace strutures subjected lateral impulsive loading. Methods Structures were modeled as rigid-perfectly plastic free-free stepped beams. Basic equations of motion un set up f...Aim To analyze dynamic failure of aerospace strutures subjected lateral impulsive loading. Methods Structures were modeled as rigid-perfectly plastic free-free stepped beams. Basic equations of motion un set up for analysis. Results Final pat deformation and rigid motion solutions were determined for a uniform impulsive loading. The critical rupture conditions for a space shuttle and a missile were obtained. Conclusion Failure is possible for aerospace structures under a uniform impulsive loading, but it is mere difficult in space.展开更多
The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of...The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of the oil film in the journal bearing and straightforward elasticity theory are considered in the analysis.Based on the structure stiffness equivalent characteristic,a simple stepped shaft can reflect the entire complex structure model.The existing lubrication model,which does not consider this angle component,is not very precise for journal bearings.Film pressure,misalignment angle,velocity field,oil leakage,and temperature field were calculated and compared in the journal bearing analysis.The results indicate that bearing performances are greatly affected by misalignment caused by the asymmetric structure.A simple stepped shaft can effectively represent a misaligned journal bearing in a rotor-bearing system.展开更多
During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped...During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbu- lence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to pro- totypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels al- though little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein.展开更多
In the present paper,the hydrodynamic performance of stepped planing craft is investigated by computational fluid dynamics(CFD)analysis.For this purpose,the hydrodynamic resistances of without step,one-step,and two-st...In the present paper,the hydrodynamic performance of stepped planing craft is investigated by computational fluid dynamics(CFD)analysis.For this purpose,the hydrodynamic resistances of without step,one-step,and two-step hulls of Cougar planing craft are evaluated under different distances of the second step and LCG from aft,weight loadings,and Froude numbers(Fr).Our CFD results are appropriately validated against our conducted experimental test in National Iranians Marine Laboratory(NIMALA),Tehran,Iran.Then,the hydrodynamic resistance of intended planing crafts under various geometrical and physical conditions is predicted using artificial neural networks(ANNs).CFD analysis shows two different trends in the growth rate of resistance to weight ratio.So that,using steps for planing craft increases the resistance to weight ratio at lower Fr and decreases it at higher Fr.Additionally,by the increase of the distance between two steps,the resistance to weight ratio is decreased and the porpoising phenomenon is delayed.Furthermore,we obtained the maximum mean square error of ANNs output in the prediction of resistance to weight ratio equal to 0.0027.Finally,the predictive equation is suggested for the resistance to weight ratio of stepped planing craft according to weights and bias of designed ANNs.展开更多
The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM(Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finit...The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM(Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finite element code DEFORM 3D.According to the effective plastic strain,the mean stress and the mean plastic strain distribution of the radial forging,the forging penetration efficiency(FPE) was studied throughout each operation.The results show that the effective plastic strain in the center of the forging is always greater than zero for the desirable larger axial drawing velocity.The mean stress in the center of the workpiece is proposed to describe hydrostatic pressure in this paper.There is compressive strain layer beneath the surface of the workpiece to be found,while there is tensile strain core in the center of the workpiece.These results could be a valuable reference for designing the similar forging operations.展开更多
A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yus...A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.展开更多
The theory of compressed sensing （CS） provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target refle...The theory of compressed sensing （CS） provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target reflectivity, two imaging methods based on CS, termed the CS-based 2D joint imaging algorithm and the CS-based 2D decoupled imaging algorithm, are proposed. These methods incorporate the coherent mixing operation into the sparse dictionary, and take random measurements in both range and azimuth directions to get high resolution radar images, thus can remarkably reduce the data rate and simplify the hardware design of the radar system while maintaining imaging quality. Ex- periments from both simulated data and measured data in the anechoic chamber show that the proposed imaging methods can get more focused images than the traditional fast Fourier trans- form method. Wherein the joint algorithm has stronger robustness and can provide clearer inverse synthetic aperture radar images, while the decoupled algorithm is computationally more efficient but has slightly degraded imaging quality, which can be improved by increasing measurements or using a robuster recovery algorithm nevertheless.展开更多
Model tests and numerical analyses of stepped reinforced retaining wall were performed to investigate the effects of rheology of backfill and creep of geogrids on the long-term performance of the structure.The geogrid...Model tests and numerical analyses of stepped reinforced retaining wall were performed to investigate the effects of rheology of backfill and creep of geogrids on the long-term performance of the structure.The geogrid tensions,soil pressures,wall deformations and foundation pressure were measured during model construction and loading.A visco-elasto-plastic model and an empirical nonlinear visco-elastic model were utilized to simulate the stresses and deformations of geogrid-reinforced earth-retaining wall under long-term loads.By comparing test data with numerical results,it is shown that the foundation pressure distribution is nonlinear,and the lateral constraint of geogrids for backfill can cause a redistribution of foundation pressure.The curve of soil pressure is outside convex at each step initially,and it is close to the distribution for the case of vertical wall subsequently.The variation trend of geogrid tensions at different heights is obtained.Moreover,the failure mechanism and development mode of potential slip surface in retaining wall are proposed.展开更多
Stability assessment of slopes has historically been performed assuming soils to be homogeneous in two-dimensional(2D) cases. In real cases, soils are usually inhomogeneous, and each slope collapse indicates a three-d...Stability assessment of slopes has historically been performed assuming soils to be homogeneous in two-dimensional(2D) cases. In real cases, soils are usually inhomogeneous, and each slope collapse indicates a three-dimensional(3D) nature. Based on a 3D rotational failure mechanism, this work develops an approach to account for the impact of the vertical strength inhomogeneity on the 3D stability of stepped slopes. Seismic actions are taken into account by introducing the concept of a horizontal seismic coefficient. An upper-bound expression for stability factors is derived in the light of the kinematic approach, and the most critical solution is obtained from an optimization programming. In comparison with the previously published solutions, the validity of the proposed method is shown. A sensitivity analysis is carried out to discuss parametric effects on the stability of 3D stepped inhomogeneous slopes.展开更多
基金supported by the Scientific and Technical Research Council of Turkey (TUBITAK) under project No. 104M427
文摘In this study, the vibrations of multiple stepped beams with cubic nonlinearities are considered. A three-to-one internal resonance case is investigated for the system. A general approximate solution to the problem is found using the method of multiple scales （a perturbation technique）. The modulation equations of the amplitudes and the phases are derived for two modes. These equations are utilized to determine steady state solutions and their stabilities. It is assumed that the external forcing frequency is close to the lower frequency. For the numeric part of the study, the three-to-one ratio in natural frequencies is investigated. These values are observed to be between the first and second natural frequencies in the cases of the clamped-clamped and clamped-pinned supports, and between the second and third natural frequencies in the case of the pinned-pinned support. Finally, a numeric algorithm is used to solve the three-to-one internal resonance. The first mode is externally excited for the clamped-clamped and clamped-pinned supports, and the second mode is externally excited for the pinned-pinned support. Then, the amplitudes of the first and second modes are investigated when the first mode is externally excited. The amplitudes of the second and third modes are investigated when the second mode is externally excited. The force-response, damping-response, and .frequency- response curves are plotted for the internal resonance modes of vibrations. The stability analysis is carried out for these plots.
基金supported by the National Natural Science Foundation of China(6112010600461225005)
文摘A grating lobes suppression method for chirp-subpulse stepped frequency（CSSF） signals is proposed, which is applied to deformation monitoring using the ground based synthetic aperture radar（GB-SAR） system. This method is based on accurate estimation and correction of the phase and amplitude error along two dimensions（range and azimuth）, i.e., the error estimation inside the subpulse（in-subpulse error） and across the stepped frequency subpulses（cross-subpulse error） of transmitted CSSF signals. Validated both with simulated data and experimental data recorded in the deformation monitoring campaign, it can be seen that the method as well as the relative conclusions can be fully and effectively applied to most of the stepped frequency systems.
文摘In this study, the influence of geometrical parameters on the curve veering phenomenon in a tor-sional system with stepped shaft is investigated. Three approximate solutions including finite el-ement, Rayleigh-Ritz and discretization methods, along with an exact solution are employed to obtain the natural frequencies of the structure. The study reveals that, under specific circumstances, the results obtained by approximate methods are very close to the exact solution. The curve veering behavior is manifested irrespective of the method employed. It is concluded that for the structure studied the curve veering behavior is not because of the approximate techniques used to compute the natural frequencies, and is an inherent behavior of the structure.
基金supported by the National Natural Science Foundation of China(No.52077137).
文摘Against the backdrop of China’s“dual-carbon”target,clean energy generation currently accounts for about 3.8 trillion kilowatt-hours,or 39.7 percent of total power generation,establishing a reasonable market trading mechanism while enhancing the low-carbon economic benefits of the integrated energy system(IES)and optimizing the interests of various entities within the distribution system has become a significant challenge.Consequently,this paper proposes an optimization strategy for a low-carbon economy within a multi-agent IES that considers carbon capture systems(CCS)and power-to-gas(P2G).In this framework,the integrated energy system operator(IESO)acts as the primary leader,while energy suppliers(ES),energy storage operators(ESO),and load aggregators(LA)follow.At the level of low-carbon technology,a coupling model of P2G and CCS is developed,leading to the establishment of an IES that incorporates energy conversion and storage equipment.Economically,effective control of system carbon emissions in market trading is progressively established.Lastly,the trading decision model of the system is integrated within a master-slave game framework,utilizing an improved differential evolution algorithm in conjunction with the distributed equilibrium method of quadratic programming for solution.The calculation example demonstrates that the strategy safeguards the benefits for both parties in the game and achieves energy savings and carbon reduction for the system.
基金Projects(52208369,52309138,52108320)supported by the National Natural Science Foundation of ChinaProjects(2023NSFSC0284,2025ZNSFSC0409)supported by the Sichuan Science and Technology Program,ChinaProject(U22468214)supported by the Joint Fund Project for Railway Basic Research by the National Natural Science Foundation of China and China State Railway Group Co.,Ltd.
文摘In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.
基金Project of the 14th Five-Year Plan for Educational Science in Liaoning Province(JG24DB234)Project of Graduate Education and Teaching Reform Research in Liaoning Province(LNYJG2023115)。
文摘This paper introduces the experience and practice in constructing the practical teaching system for the course“Electric Machine and Drive.”In response to the current status of cultivating innovative practical abilities among electrical engineering majors,based on the independently developed virtual simulation experimental teaching platform for Electric Machine and Drive,a stepped practical teaching process consisting of“classroom teaching-experimental teaching-comprehensive training-scientific inquiry”has been elaborately designed.A hierarchical practical teaching model for the second classroom has also been established.With teaching objectives as the optimization index,the teaching content,methods and means have been optimized;the teaching process has been organized and implemented in the form of team collaboration,thus constructing a comprehensive,stepped,hierarchical,and closed-loop innovative practical teaching system.This achievement provides references and assistance for the practical teaching of the same or similar majors in other colleges and universities.
文摘BACKGROUND Owing to age-related physiological declines,elderly patients undergoing radical gastrectomy(RG)often experience physical and psychological challenges.Hence,appropriate nursing strategies need to be identified for optimizing patient outcomes.AIM To evaluate the effects of the Neuman Systems Model-guided stepped care intervention(NGSC)model on postoperative physical and psychological recovery in elderly patients with gastric cancer who underwent RG.METHODS In total,80 elderly patients(≥65 years old)who underwent RG at the Shanxi Fenyang Hospital between January 2023 and June 2024 were included and randomly divided as follows:Control group(n=40,those receiving conventional stepped care intervention);observation group(n=40,those receiving NGSC).Postoperative recovery indices,anxiety/depression scores(Self-Rating Anxiety Scale/Self-Rating Depression Scale),quality of life(36-item short form health survey),and adverse event rates were compared between the groups.RESULTS Compared with the control group,the observation group presented significantly shorter recovery times for first bowel sounds,ambulation,flatus,oral intake,catheter removal,and hospitalization(all P<0.05).Notably,in the observation group,Self-Rating Anxiety Scale/Self-Rating Depression Scale scores and the adverse event rate were significantly lower(all P<0.05),whereas 36-item short form health survey scores were higher(P<0.05),compared with those in the control group.CONCLUSION Overall,the findings of this study show that the proposed NGSC model accelerates postoperative recovery,alleviates psychological distress,improves quality of life,and reduces complications in elderly patients with gastric cancer who underwent RG,presenting potential for clinical application.
文摘To address the issues of unclear carbon responsibility attribution,insufficient renewable energy absorption,and simplistic carbon trading mechanisms in integrated energy systems,this paper proposes an electricheat-hydrogen integrated energy system(EHH-IES)optimal scheduling model considering carbon emission stream(CES)and wind-solar accommodation.First,the CES theory is introduced to quantify the carbon emission intensity of each energy conversion device and transmission branch by defining carbon emission rate,branch carbon intensity,and node carbon potential,realizing accurate tracking of carbon flow in the process of multi-energy coupling.Second,a stepped carbon pricing mechanism is established to dynamically adjust carbon trading costs based on the deviation between actual carbon emissions and initial quotas,strengthening the emission reduction incentive.Finally,a lowcarbon economic dispatch model is constructed with the objectives of minimizing operation cost,carbon trading cost,wind-solar curtailment penalty cost,and energy loss.Simulation results show that compared with the traditional economic dispatch scheme 3,the proposed schemel reduces carbon emissions by 53.97%and wind-solar curtailment by 68.89%with a 16.10%increase in total cost.This verifies that the model can effectively improve clean energy utilization and reduce carbon emissions,achieving low-carbon economic operation of EHH-IES,with CES theory ensuring precise carbon flow tracking across multi-energy links.
基金State Grid Gansu Electric Power Company Science and Technology Program(Grant No.W24FZ2730008)National Natural Science Foundation of China(Grant No.51767017).
文摘In the background of the low-carbon transformation of the energy structure,the problem of operational uncertainty caused by the high proportion of renewable energy sources and diverse loads in the integrated energy systems(IES)is becoming increasingly obvious.In this case,to promote the low-carbon operation of IES and renewable energy consumption,and to improve the IES anti-interference ability,this paper proposes an IES scheduling strategy that considers CCS-P2G and concentrating solar power(CSP)station.Firstly,CSP station,gas hydrogen doping mode and variable hydrogen doping ratio mode are applied to IES,and combined with CCS-P2G coupling model,the IES low-carbon economic dispatch model is established.Secondly,the stepped carbon trading mechanism is applied,and the sensitivity analysis of IES carbon trading is carried out.Finally,an IES optimal scheduling strategy based on fuzzy opportunity constraints and an IES risk assessment strategy based on CVaR theory are established.The simulation shows that the gas-hydrogen doping model proposed in this paper reduces the operating cost and carbon emission of IES by 1.32%and 7.17%,and improves the carbon benefit by 5.73%;variable hydrogen doping ratio model reduces the operating cost and carbon emission of IES by 3.75%and 1.70%,respectively;CSP stations reduce 19.64%and 38.52%of the operating costs of IES and 1.03%and 1.80%of the carbon emissions of IES respectively compared to equal-capacity photovoltaic and wind turbines;the baseline price of carbon trading of IES and its rate of change jointly affect the carbon emissions of IES;evaluating the anti-interference capability of IES through trapezoidal fuzzy number and weighting coefficients,enabling IES to guarantee operation at the lowest cost.
文摘Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtain the HRR profile of a target. For moving targets which are of great importance in practical radar usage, autofocusing,i.e. phase correction, is a necessary and critical step of the synthetic HRR processing. The purpose of autofocusing is to remove the radial motion effect of the target from radar echoes, and only reserve the stepped frequency effect which is the basis of synthetic HRR capability. We investigate two autofocusing approaches for synthetic HRR radars using stepped frequency waveform in this paper. The first is motion fitting method. This method depends on a certain parametric model, and is computationally expensive. Then we propose the iterative dominant scatterer method. It is robust, non parametric and simple in computation in comparison with the motion fitting method. Experimental results based on data acquired by using a metallised scale model B 52 in a microwave anechoic chamber reveal the validity and effectiveness of the method.
文摘An integrated system for assembly planning and design (INSAPS) is presented in which product data can be exchanged between assembly planning and assembly design on the basis of standard for exchange of product data model (STEP). The system consists of CAD system, product modeling system, assembly planning system. The product model is organized according to the STEP, uses mostly the entities of IR (integrated resources) and partly self defined entities which is necessary for assembly planning. A simple method of assembly sequence generation is presented which is suitable for complex assembly planning. The generated assembly sequences are evaluated considering the optimization of total assembly time. The results of assembly planning are feedback to the stage of assembly design to improve design.
文摘Aim To analyze dynamic failure of aerospace strutures subjected lateral impulsive loading. Methods Structures were modeled as rigid-perfectly plastic free-free stepped beams. Basic equations of motion un set up for analysis. Results Final pat deformation and rigid motion solutions were determined for a uniform impulsive loading. The critical rupture conditions for a space shuttle and a missile were obtained. Conclusion Failure is possible for aerospace structures under a uniform impulsive loading, but it is mere difficult in space.
基金Project supported by the National Natural Science Foundation of China (No. 60879002)the Tianjin Support Plan of China(No. 10ZCKFGX03800)
文摘The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of the oil film in the journal bearing and straightforward elasticity theory are considered in the analysis.Based on the structure stiffness equivalent characteristic,a simple stepped shaft can reflect the entire complex structure model.The existing lubrication model,which does not consider this angle component,is not very precise for journal bearings.Film pressure,misalignment angle,velocity field,oil leakage,and temperature field were calculated and compared in the journal bearing analysis.The results indicate that bearing performances are greatly affected by misalignment caused by the asymmetric structure.A simple stepped shaft can effectively represent a misaligned journal bearing in a rotor-bearing system.
基金Project supported by the National Council for Science and Tech-nology of Mexico (CONACYT)
文摘During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbu- lence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to pro- totypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels al- though little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein.
文摘In the present paper,the hydrodynamic performance of stepped planing craft is investigated by computational fluid dynamics(CFD)analysis.For this purpose,the hydrodynamic resistances of without step,one-step,and two-step hulls of Cougar planing craft are evaluated under different distances of the second step and LCG from aft,weight loadings,and Froude numbers(Fr).Our CFD results are appropriately validated against our conducted experimental test in National Iranians Marine Laboratory(NIMALA),Tehran,Iran.Then,the hydrodynamic resistance of intended planing crafts under various geometrical and physical conditions is predicted using artificial neural networks(ANNs).CFD analysis shows two different trends in the growth rate of resistance to weight ratio.So that,using steps for planing craft increases the resistance to weight ratio at lower Fr and decreases it at higher Fr.Additionally,by the increase of the distance between two steps,the resistance to weight ratio is decreased and the porpoising phenomenon is delayed.Furthermore,we obtained the maximum mean square error of ANNs output in the prediction of resistance to weight ratio equal to 0.0027.Finally,the predictive equation is suggested for the resistance to weight ratio of stepped planing craft according to weights and bias of designed ANNs.
文摘The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM(Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finite element code DEFORM 3D.According to the effective plastic strain,the mean stress and the mean plastic strain distribution of the radial forging,the forging penetration efficiency(FPE) was studied throughout each operation.The results show that the effective plastic strain in the center of the forging is always greater than zero for the desirable larger axial drawing velocity.The mean stress in the center of the workpiece is proposed to describe hydrostatic pressure in this paper.There is compressive strain layer beneath the surface of the workpiece to be found,while there is tensile strain core in the center of the workpiece.These results could be a valuable reference for designing the similar forging operations.
基金Special Fund for Earthquake Research under Grant No.201208013National key Technology R&D Program under Grant No.2012BAK15B05Basic Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2010A04
文摘A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.
基金supported by the Prominent Youth Fund of the National Natural Science Foundation of China (61025006)
文摘The theory of compressed sensing （CS） provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target reflectivity, two imaging methods based on CS, termed the CS-based 2D joint imaging algorithm and the CS-based 2D decoupled imaging algorithm, are proposed. These methods incorporate the coherent mixing operation into the sparse dictionary, and take random measurements in both range and azimuth directions to get high resolution radar images, thus can remarkably reduce the data rate and simplify the hardware design of the radar system while maintaining imaging quality. Ex- periments from both simulated data and measured data in the anechoic chamber show that the proposed imaging methods can get more focused images than the traditional fast Fourier trans- form method. Wherein the joint algorithm has stronger robustness and can provide clearer inverse synthetic aperture radar images, while the decoupled algorithm is computationally more efficient but has slightly degraded imaging quality, which can be improved by increasing measurements or using a robuster recovery algorithm nevertheless.
基金Supported by National Natural Science Foundation of China (No. 50678032 and No. 90715042)Key Project of Ministry of Education of China (No. 210176)
文摘Model tests and numerical analyses of stepped reinforced retaining wall were performed to investigate the effects of rheology of backfill and creep of geogrids on the long-term performance of the structure.The geogrid tensions,soil pressures,wall deformations and foundation pressure were measured during model construction and loading.A visco-elasto-plastic model and an empirical nonlinear visco-elastic model were utilized to simulate the stresses and deformations of geogrid-reinforced earth-retaining wall under long-term loads.By comparing test data with numerical results,it is shown that the foundation pressure distribution is nonlinear,and the lateral constraint of geogrids for backfill can cause a redistribution of foundation pressure.The curve of soil pressure is outside convex at each step initially,and it is close to the distribution for the case of vertical wall subsequently.The variation trend of geogrid tensions at different heights is obtained.Moreover,the failure mechanism and development mode of potential slip surface in retaining wall are proposed.
基金Project(51378510)supported by the National Natural Science Foundation of China
文摘Stability assessment of slopes has historically been performed assuming soils to be homogeneous in two-dimensional(2D) cases. In real cases, soils are usually inhomogeneous, and each slope collapse indicates a three-dimensional(3D) nature. Based on a 3D rotational failure mechanism, this work develops an approach to account for the impact of the vertical strength inhomogeneity on the 3D stability of stepped slopes. Seismic actions are taken into account by introducing the concept of a horizontal seismic coefficient. An upper-bound expression for stability factors is derived in the light of the kinematic approach, and the most critical solution is obtained from an optimization programming. In comparison with the previously published solutions, the validity of the proposed method is shown. A sensitivity analysis is carried out to discuss parametric effects on the stability of 3D stepped inhomogeneous slopes.
