最新刊期
卷 58 ， 期 5 ， 2024
- 摘要：The innovation breakthrough in energy storage technology has become a crucial driver for transformative and disruptive changes in the global energy landscape. It is an important measure to achieve the strategic goals of “carbon peak and carbon neutrality”. In this regard, the research team on “Advanced Physical Energy Storage Technology” at Xi'an Jiaotong University has creatively proposed a new type of combined pumped-hydro and compressed air energy storage system. This technology applies air and water as the intermediate working mediums and conducts air turbine and hydraulic machinery as the power output equipment to achieve high-efficiency isothermal compression and expansion of the energy storage medium. Compared to traditional compressed air energy storage technology, the novel combined pumped-hydro and compressed air energy storage system features fast response, high efficiency, low investment cost, and so forth. Throughout the course of more than ten years of research and development, the team has completed the research on the performance and time-domain characteristics of key equipment and energy storage systems, achieved a significant breakthrough in key generic technologies of fluid machinery, and finished the development and application of life cycle assessment software for compressed air energy storage system, providing solid theoretical and data support for the large-scale promotion and application of gas-liquid hybrid compressed air energy storage technology.关键词：compressed air energy storage;near-isothermal compression;combined pumped-hydro and compressed air energy storage system;efficient operation785|27|0更新时间：2025-07-28
- 摘要：Ensuring a continuous supply of gas resources is a crucial requirement for China's energy security. However, the steady production of gas wells is often hindered by the issue of liquid loading. To maintain a consistent gas production, it is important to implement effective drainage and gas recovery technologies. In China, 60% of the gas wells undergo liquid loading, resulting in production declining by more than 23% per year, and the worse part is that the number of liquid loading wells annually increases by 5%. The conventional method of drainage gas recovery is only appropriate for shallow vertical wells with minimal gas outflow and brings about a low drainage efficiency since the multiphase flow characteristics of gas wells are not well understood. Therefore, this paper will highlight the current research conducted by our team on the theory of enhanced liquid carrying in multiphase flow and the key technologies of drainage gas recovery in gas wells. We proposed the theory of enhanced liquid carrying, which revolves around the regulation of gas-liquid flow structure. It overcomes the constraint of the traditional critical liquid carrying theory, which is only applicable to annular-mist flow. We developed a set of key technologies for efficient and cost-effective drainage gas recovery that is suitable for various liquid loading states in gas wells under different liquid loading conditions, including oil-resistant and salinity-resistant foam drainage, complex wellbore velocity string drainage, supersonic nozzle atomization drainage, plunger relay lift drainage, and more. The theoretical and technical achievements have been applied to 11 gas fields and 12 000 gas wells, accounting for more than 30% of all the liquid-loading gas wells in China.关键词：multiphase flow;enhanced liquid carrying;drainage and gas recovery;gas production;energy security196|50|0更新时间：2025-07-28
- 摘要：The research conducted focused on the development of strengthening mechanism and manufacturing technique for copper-based materials with high-strength and high conductivity. These new mechanisms were proposed, namely the “strengthening second phase” to enhance the strength of the dispersion-strengthening phase, “super-saturated solid solution” to increase the concentration of the dispersion-strengthening phase in the matrix, and “flexible coating in copper grain boundaries” to improve the high temperature strength of these materials. These findings provide a theoretical foundation for the composition and microstructure design of high-strength and high-conductivity copper alloys. Over 20 relevant research papers on this topic were published in reputable journals. Furthermore, a continuous fabrication technique was developed for the scale green manufacture of high-strength and high-conductivity copper materials. This manufacturing process is characterized by its simplicity, with short duration, and the resulting copper materials exhibiting a fully compact structure, with no segregation in microstructure, and high performance uniformity. The implementation of this project was assessed to be worth 15 million RMB, and a new company was established with an investment structure consisting of 3 million RMB cash payment to Xi'an Jiaotong University and a 12 million RMB investment owned by the inventor. A mixed ownership enterprise was formed in collaboration with Shaanxi Coal Group, and the first production line of 1 000 tons has already been completed. The result products have been utilized by a number of national leading enterprises. Additionally, plans are underway to construct a 10 000 ton production line in the near future. These achievements have great significance implications for the advancement of key materials in various fields such as national high-speed rail, chips, and engines.关键词：high strength and high conductivity copper;strengthen mechanism;green manufacture;technical transfer185|18|0更新时间：2025-07-28
- 摘要：To tackle the challenge of convolutional neural network and its integration methods with denoising preprocessing methods struggling to effectively extract useful signal features amidst high noise environments and low-quality data, a deep convolutional neural network model based on the Geronimo-Hardin-Massopust multiwavelet decomposition(GHMMD-DCNN)is proposed. The model's concept revolves around deeply integrating the multiwavelet packet decomposition with the convolutional neural network. In other words, this involves the creation of multiple first-level multiwavelet decomposition layers to extract the low-frequency and high-frequency signal components, and these layers are lined alternately with the convolutional layer. This approach enables the model to extract and learn the useful time-frequency information of the signal on a multiscale basis. The signal decomposition and the feature learning are executed alternately, and robust feature extraction is realized even under strong noise conditions. Tests are carried out using aerospace high-speed bearing vibration data under different working conditions. The results show that the proposed model is able to reach stable convergence quickly and the recognition accuracy surpasses 99.9%. The proposed method showcases superior fault recognition accuracy and stability in the presence of significant noise interference compared to contrast methods, which demonstrates its excellent anti-noise ability. In the test of fewer training samples, the proposed method achieves an impressive average diagnosis accuracy of 91.19% with only 60 training samples per class. This represents a 13.19% enhancement over alternative methods, verifying the GHMMD-DCNN's exceptional low-sample generalization ability.关键词：multiwavelet decomposition;convolutional neural network;deep learning;bearing fault diagnosis236|11|0更新时间：2025-07-28
- 摘要：To address issues such as poor flexibility, low efficiency, and safety concerns in dynamic path planning in the crowded pedestrian environments, an adaptive dynamic window method based on social constraints(social_DWA)in the social interaction space is proposed, and it is used to solve local path planning problems of service robots. Firstly, the asymmetric Gaussian formula is employed to model interaction spaces of single pedestrian and groups. Secondly, based on the original dynamic window method, the dynamic pedestrian azimuth constraint is implemented to steer clear of dynamic pedestrians. Enhancements are made to the distance evaluation function to classify and ascertain the safety distances from pedestrians, pedestrian groups, and general obstacles. Finally, an adaptive adjustment strategy of speed weight is proposed to optimize the movement speed of service robots while passing through social interaction areas with varying densities. To verify the effectiveness of the algorithm, the path planning simulation experiments of the social_DWA algorithm, the traditional DWA algorithm, and the FIDWA algorithm are carried out in two simulated social scenarios featuring different complexities. The results show that the motion time consumed by the social_DWA algorithm is reduced by 1.53 and 0.43 s compared with the traditional DWA algorithms and FIDWA algorithms in scenario 1, and 26.3 and 2.86 s lower than the traditional DWA algorithms and FIDWA algorithms in scenario 2, respectively.Compared with the traditional DWA algorithm and FIDWA algorithm, the social_DWA algorithm maintains an effective pedestrian safety distance and ensures more rational running trajectories. The validation confirms the social_DWA algorithm's superiority in pedestrian avoidance and environmental adaptability.关键词：service robots;path planning;dynamic windows approach;self-adaptation;humanization104|6|0更新时间：2025-07-28
- 摘要：The 3D point cloud classification and segmentation networks ignore the redundant information in the fusion features, lack the ability to amplify the proportion of effective features, and cannot fully explore the expressiveness of features. Based on the CurveNet network, this paper proposes a method that can filter and enrich the fusion features, and the recognition and segmentation effect of point cloud reaches a relatively advanced level. Firstly, a feature selection subnetwork with filtering ability for fusion features is proposed, which combines TopK operator and a scoring mechanism to select fusion features containing valid information and adaptively assign weight to the selected features. Secondly, two new branches are added to the aggregation curve feature module, so as to learn the curve internal point distance features and the curve line distance features, respectively, and extract the internal correlation of each branch through the quick channel affinity attention mechanism, which enhances the information description ability of the network features. The experimental results show that the accuracy of the classification task on the ModelNet40 dataset reaches 93.8%, and the average intersection over union of the segmentation task on the ShapeNet Part dataset reaches 86.4%. Compared with the benchmark network, the classification effect and segmentation effect are improved, which proves the effectiveness of the proposed algorithm.关键词：3D point cloud;fusion feature screening;curve feature;attentive mechanism;classification and segmentation114|19|0更新时间：2025-07-28
- 摘要：A sliding mode anti-disturbance control method is proposed to solve the problem of chattering during volume switching in the application of sliding mode control in the pressure pulse testing system. The pressure pulse testing system is reduced and simplified by applying singular perturbation theory, facilitating the design and application of the controller. Based on the reduced-order model of the system, an extended state observer is constructed to estimate unknown disturbances such as uncertain parameters in the system and volume switching of the workpiece. The estimated disturbance values are then used as feedforward signals to compensate the sliding mode controller, thereby reducing the upper bound of disturbance uncertainty, thus achieving the goal of reducing the switching gain to mitigate chattering. The stability of the proposed control method is derived and demonstrated through the selection of an appropriate Lyapunov function. Simulation analysis is conducted using a joint simulation platform built with AMESim and Matlab/Simulink, and experimental verification is performed using the pressure pulse testing platform. The research results indicate that in terms of overall tracking performance, traditional sliding mode control has improved by 21.10% compared to PID, while the proposed control method has improved by 30.86% compared to PID. The proposed control method can effectively estimate and compensate for unknown disturbances, achieve smaller switching gains while maintaining control accuracy. During the volume switching of workpiece, it effectively reduces sliding mode chattering, enhancing the system's anti-disturbance capability.关键词：pressure pulse testing system;sliding mode control;unknown disturbances;singular perturbation;extended state observer111|23|0更新时间：2025-07-28
- 摘要：In view of the lack of adaptability and accuracy of traditional machine learning in the field of gesture recognition of surface electromyography(sEMG), as well as the poor performance of new users on existing models due to individual physiological and behavioral differences, an algorithm using convolutional neural network model to effectively overcome the difference in the distribution of EMG data is proposed to improve the performance of gesture recognition. A novel approach combining variational mode decomposition(VMD)of sEMG signal and convolutional neural network is proposed to enhance the performance of gesture recognition in the subject. In addition, domain adaptation and model fine-tuning techniques of transfer learning are used to increase the accuracy of gesture recognition of intra-subject sEMG. The proposed algorithm is evaluated and validated on four evaluation groups of the benchmark dataset DB1 with 3, 4, 5 and 12 classifications. In the four sets of evaluation, the average accuracies of inter-subject are 99.28%, 99.30%, 98.39% and 93.40% respectively, and the average accuracies of intra-subject are 94.05%, 92.60%, 88.38% and 70.03% respectively. Through the experimental results and own data validation, it is proved that the proposed algorithm has a good effect on the gesture recognition of sEMG signals, which is more conducive to the realization of human-computer interaction and provides a feasible solution for the development of universal sEMG equipment.关键词：domain adaptation;convolutional neural network;gesture recognition;variational mode decomposition;surface electromyography90|30|0更新时间：2025-07-28
- 摘要：In order to design the secondary air system of gas turbine accurately, the flow and heat transfer in the tenon joint gap of gas turbine rotor blade and disk are studied. The flow resistance and heat transfer characteristics of the S shaped tenon joint gap between blade and disk in gas turbine are investigated experimentally, and detailed flow field is studied numerically. Firstly, the flow resistance and Nusselt number of the gap are measured by pressure scanning valve and thermochromic liquid crystal, respectively. Then the turbulence model used in numerical calculation is validated by the experimental results, and the grid independence is verified. At last, the effects of flow and structure parameters on tenon joint gap flow and heat transfer are analyzed, in which, five different Reynolds numbers, five different relative heights of the gap and five different widths of the gap are conducted. The results show that the average Nusselt number on the left wall is consistently around 10% higher than that on the right side. As the Reynolds number increases, the flow resistance coefficient and heat transfer intensity of the assembly gap increase gradually. When the Reynolds number increases from 15 000 to 35 000, the average flow resistance coefficient and the average Nusselt number on both sides increases by 300% and 110% respectively. With the increase of the relative height of the assembly gap, the flow resistance coefficient and the wall average Nusselt number decrease gradually. Increasing the gap width leads to a 30.7% average flow resistance coefficient increase within the test range, with the average Nusselt number on both sides increasing by 95.5% and 94.9% respectively.关键词：mortise and tenon assembly gap;flow characteristic;heat transfer characteristics172|7|0更新时间：2025-07-28
- 摘要：To investigate the effects of blowing ratio and land extensions on the film cooling performance of a gas turbine blade trailing edge cutback, the delayed-detached eddy simulation(DDES)is utilized to compute the discharge coefficient, transient flow structures, and film cooling effectiveness of a trailing edge cutback model, and the experimental data is adopted to validate the reliability of DDES for the discharge coefficient and film cooling effectiveness predictions. As a result, the study determined the optimum blowing ratio for ensuring the film cooling effect at the trailing edge cutback. The findings show that the discharge coefficient rises in correspondence with an increase in the blowing ratio. However, once the blowing ratio surpasses 0.65, its impact on the discharge coefficient diminishes significantly. For the blowing ratio ranging from 0.20 to 0.65, the film cooling effectiveness at the trailing edge cutback improves with an increase in the blowing ratio. As the blowing ratio increases from 0.80 to 1.25, interactions between the coolant and hot mainstream are intensified, resulting in a slight reduction in the cooling effect. The existence of land extensions amplifies the blockage of cooling slot and inhibits the development of coolant vortices in the trailing edge cutback region, leading to premature twisting, distortion, and fragmentation of the transverse vortex system. Compared to the trailing edge cutback without land extensions, the discharge coefficient for the configuration with land extensions decreases by about 5% while the film cooling effectiveness increases by about 10.8%. The vortex shedding downstream the cooling slot and interactions between coolant and hot mainstream are the main reasons affecting the cooling effect at the trailing edge cutback. Considering both coolant consumption and film cooling effectiveness, the optimal blowing ratio for the trailing edge cutback without land extensions is identified as 0.65. Contrastingly, for the trailing edge cutback with land extensions, the preferred blowing ratio stands at 0.5.关键词：aero-engine;trailing edge cutback;land extension;film cooling;discharge coefficient;delayed-detached eddy simulation94|19|0更新时间：2025-07-28
- 摘要：As an important component of the secondary air system in gas turbines, rim seal can effectively prevent the gas ingestion. However, the excessive cooling air significantly affects the aerodynamic performance of turbine stage due to the coolant egress and mixing with the mainstream through rim seal. The flow characteristics of rim seal and aerodynamic performance of turbine stage was numerically investigated using three-dimensional unsteady Reynolds averaged Navier-Stokes(URANS)and shear stress transfer(SST)k-ω turbulence model. The numerical sealing effectiveness of rim seal is consistent with the experimental data. The accuracy of the employed numerical method is validated. The flow characteristics of the rim seal and aerodynamic performance of turbine stage is studied at three different coolant flow rates. The flow pattern in the stator-rotor cavity, gas ingestion and coolant egress characteristics are analyzed. The obtained results show that the inner cavity of the rim seal is completely sealed at three coolant flow rates. A lower coolant flow rate for the last stage can achieve a higher sealing effectiveness of rim seal. The average sealing effectiveness of the outer cavity rotor disk is 4.4% higher than that of the stator disk at the lowest coolant flow rate. For the last stage of turbine, externally-induced ingress caused by the uneven distribution of mainstream circumferential pressure is dominant and the pressure field near the leading edge of blades has a greater impact on gas ingestion than the pressure field at the wake of vanes. For every 1.0% increase in coolant mass flow ratio, the total-to-total efficiency of the turbine stage decreases by around 1.0%. The impact of cooling air outflow from the rim seal on the aerodynamic performance of downstream blades is greater. The flow direction of the egress lags behind the mainstream in the tangential direction, causing the mixed airflow to strike the leading edge of the suction surface of blades at a negative angle of attack, and increasing the pressure on the leading edge of the suction surface. This research can provide a reference for studying the flow characteristics of rim seal and its impact on the aerodynamic performance of turbine stage.关键词：gas turbine;rim seal;gas ingestion;aerodynamic performance98|25|0更新时间：2025-07-28
- 摘要：To break through the limitations of ammonia combustion in engines and promote efficient and rapid combustion of ammonia, a method for igniting ammonia fuel using a hydrogen jet flame is proposed. By supplying hydrogen to the active pre-combustion chamber and premixing ammonia/hydrogen fuel in the inlet tract, stable and efficient combustion of ammonia in a large bore marine engine is achieved. The effects of inlet gas temperature, hydrogen addition ratio and main combustion chamber equivalent ratio on the ignition characteristics of the ammonia-hydrogen fuel are investigated based on numerical simulation methods and improved Otomo ammonia/hydrogen mechanism. Results show that jet flames can develop the thermodynamic environment and high active heat jets required for combustion in the main combustion chamber. At an equivalence ratio of 0.4 and no hydrogen addition, thin combustion of ammonia-fueled engines can be achieved at an inlet temperature of 450 K. Jet ignition has a more significant effect on flame development at lower hydrogen addition ratios; increasing the hydrogen addition ratio to 10.0% advances the combustion phase by 18°, but there is an increased risk of detonation; at an inlet temperature of 320 K and a hydrogen addition ratio of 2.5%, the main combustion chamber can ignite normally at a minimum equivalence ratio of 0.45, but there is a slight increase in indicated thermal efficiency as combustion approaches the theoretical air-fuel ratio. The combustion mode of active pre-combustion chamber hydrogen jet ignition shows promising potential for achieving efficient and fast combustion in ammonia engines.关键词：ammonia/hydrogen fuel;marine engine;pre-chamber;jet ignition;combustion characteristics97|93|0更新时间：2025-07-28
- 摘要：To reveal the distribution of soot particle deposition in a multi-blade centrifugal fan and mitigate such deposition, numerical simulations are conducted to investigate the trajectories and deposition characteristics of soot particles within a multi-blade centrifugal fan. The study utilizes the Fluent discrete phase model to describe particle motion, while employing the critical velocity model and the user-defined functions(UDF)to model the particle deposition on walls. In addition, the study examines the particle diameter on deposition distribution. Findings indicate that soot particles mainly deposit on the blade pressure surface, with notable accumulation near the trailing edge close to the outlet. When the complete machine is involved, the flow field within the fan becomes more turbulent due to unstable inflow conditions, thereby leading to escalating deposition levels. It is found that particles with larger diameters exhibit a higher tendency to deposit on blade surfaces owing to the dominant inertial forces. In light of deposition distributions and their causal factors, an optimization strategy is proposed to reduce the deposition on blade surfaces by cutting blades and consequently reducing the outlet installation angle. In terms of the modified blades, flow separation near the impeller outlet decreases, leading to decreased vorticity around the trailing edge of blades. Comparing the original and modified blades, numerical simulation results show a 30.75% decrease in deposition rate, while experimental outcomes demonstrate a 30.66% reduction. The close agreement underscores the effectiveness of the proposed method in mitigating the deposition of soot particles.关键词：multi-blade centrifugal fan;deposition;discrete phase model;soot particles9|23|0更新时间：2025-07-28
- 摘要：In order to explore the kinetic mechanism of hydrogen(H2)production in supercritical water, this study uses reactive molecular dynamics method to systematically compare the effects of simulation time and molecular number of methane(CH4)on the concentration-time evolution of key species and reaction channels, and to quantitatively analyze the multi-parameters influence on the pathways of CH4 consumption and H2 generation. Results indicate that CH4 can be converted into H2 and CO, together with trace number of carbon-based intermediates in supercritical water. Reaction H2O+—H〖FY〗—OH+H2 dominates the generation of H2, during which the relative number of —OH radicals and —H atoms significantly influences the output of H2. Under the conditions investigated in this study, reduction in both temperature and pressure shows limited effect on the dominant reaction pathways during CH4 consumption but presents a promotion on H2 net production. Decrease in CH4 mass concentration increases first and then decreases H2 net production, suggesting an optimal concentration of CH4 for the thermal chemistry conversion in supercritical water. The research results can provide a reference for improving the efficiency of hydrogen production of volatile components in supercritical water.关键词：molecular dynamics;supercritical water;methane;hydrogen production mechanism118|5|0更新时间：2025-07-28
- 摘要：To study how to improve the operational stability of a rocket sled on orbit under hypersonic conditions without using additional stabilizing devices, an optimization design of the aerodynamic characteristics of a hypersonic rocket sled is carried out based on numerical analysis methods, and the aerodynamic characteristics of the optimized sled are studied under different operating conditions through wind tunnel tests. Firstly, a numerical analysis method for the aerodynamic characteristics of rocket sleds based on SST turbulence model and N-S control equation is developed, and the accuracy of the calculation method is verified through the classical double ellipsoid model. Then, based on the numerical analysis method of aerodynamic characteristics, the aerodynamic shape design of the sled body is conducted, and elevation angle, lateral deviation angle of the rectifier board, and position of the front and rear slipper are optimized. Finally, the aerodynamic characteristics of the optimized sled body under different operating conditions are studied through wind tunnel tests, and the effects of Mach number, Reynolds number, and track and ground effects are analyzed. The accuracy of the numerical analysis method for hypersonic aerodynamic characteristics of rocket sleds is about 86.94%, which can be used to simulate the aerodynamic characteristics of rocket sleds in hypersonic flow fields. At Ma=5, the optimized model reduces aerodynamic drag by 23.57% and aerodynamic lift by 38.49% compared to the pre-optimized model. As the Mach number increases, the drag coefficient of the sled body shows a decreasing trend, for example, when the Mach number increases from 4 to 6, the drag coefficient of the sled body decreases by 19.98%. The lift coefficient and pitch moment coefficient of the sled body both increase with the increase of Reynolds number. At Ma=5, when the Reynolds number changes from 1.80×107 to 3.60×107, the drag coefficient and pitch moment coefficient of the sled increase by 8.95% and 13.09% respectively. The track and ground will lead to a simultaneous increase in the resistance coefficient, lift coefficient, and pitch moment coefficient of the sled body, with the pitch moment coefficient changing the most significantly. The average increment of pitch moment coefficient in the three comparative experiments is about 992%. The research can provide data support for the design of hypersonic rocket sleds and has certain engineering application value.46|30|0更新时间：2025-07-28
- 摘要：It is difficult to balance the high heat absorption efficiency and high outlet temperature in the particle solar receiver, and the thermal radiation absorption performance of particles determines its thermal efficiency and the upper limit of temperature rise. Therefore, based on the Monte-Carlo method, a radiative transfer model of stationary particle groups under external parallel radiation projection is established to investigate the effects of the geometry structure of particle groups, particle sizes, particle radiative properties, irradiation conditions and other factors on the transmission of thermal radiation. The results show that the particle groups' absorption duration is independent of the particle size and geometry structure, but is in direct proportion to the volume fraction, and shortens with the increase of the external radiation intensity or the absorptivity on the particle surface. For a certain particle group, the equilibrium temperature depends mainly on external radiation intensity, and the overall absorption rate relies mainly on the absorptivity of particle surface. For a given geometry structure of the particle group, both are positively correlated with the particle size, and have similar variation behavior as the volume fraction increases. In different geometry structures, increasing the volume fraction of particles enhances the external radiation absorption while increasing the escape of self-generated radiation. Among the existing structures, the overall absorptivity under the tessellated staggered structure and the sector structure have peaks with the increase of volume fraction. Of these, the sector structure requires the smallest particle concentration to reach the highest equilibrium temperature and efficiency. According to the calculation results, an empirical correlation formula for the overall absorptivity of the particle population is proposed, whose relative error subject to the definition formula calculation value is less than 15%. The results of this paper can provide a reference for the computation of radiation transfer of moving particle populations, as well as the design and regulation of particle solar receivers.关键词：thermal radiation;particle radiative property;geometry structure;absorption duration;absorptivity;equilibrium temperature61|23|0更新时间：2025-07-28
- 摘要：With rapid advancements in air conditioners and increasing international copper prices, the heat exchangers used in the refrigeration and air conditioning industry frequently face technical challenges that hinder performance degradation as efforts focus on compact size and cost efficiency. In response, a study is conducted on a dual-mode room air conditioner with a finned-tube outdoor heat exchanger. The outer diameter of the heat exchange tubes is reduced from 7 mm to 5 mm alongside the circuit optimization. The goal is to achieve the performance of the Φ5 mm heat exchanger at the level of the initial prototype and effectively reduce the cost of the heat exchanger. Firstly, the performance test of the original prototype is carried out across five standard operating conditions. Subsequently, CoilDesigner is utilized to assess the impact of tube diameter reduction on the heat exchanger's performance. Simulation results indicate a minor improvement in the heat transfer capacity of the Φ5 mm heat exchanger without any circuit alterations. However, the refrigerant pressure drop increases by 4—7 times. Furthermore, five targeted circuit schemes are designed to examine the impact of factors such as the number of circuits and confluence locations of circuits on the heat transfer and pressure drop characteristics of the heat exchanger. The study summarizes an optimization approach for the circuit of small-diameter finned-tube heat exchangers. Three optimization schemes are developed for the Φ5 mm outdoor heat exchanger. After simulating and evaluating the feasibility of these three schemes, prototypes are generated for performance testing. The experimental results reveal that scheme(3)performs on par with the original heat exchanger while concurrently reducing material costs by 34.6%.关键词：room air conditioner;finned-tube heat exchanger;small tube diameter;circuitry optimization82|25|0更新时间：2025-07-28
- 摘要：In response to the low system efficiency and heat source utilization in geothermal power generation technology, the thermal characteristics of a single-screw expander used in a total-flow cycle power generation system as an alternative to the traditional steam turbine are analyzed. Based on the mass and energy conservation equations and wet-steam virial equation of state, a thermodynamic model is formulated for the total-flow expansion involving liquid flash and vapor-liquid equilibrium. The influence of inlet temperature and dryness on the state of vapor-liquid two-phase working medium and the thermal characteristics of the expander is examined. The results show that elevating the inlet temperature from 140 ℃ to 170 ℃ enhances the mass, pressure, and temperature of the wet steam working medium, and the output power of the single-screw expander rises from 210 kW to about 260 kW, with the isentropic efficiency becoming optimal at 77% at the inlet temperature of 160 ℃. Improving the inlet steam dryness diminishes the quality of the working medium of the wet steam entering the working chamber, causing a subsequent reduction in medium pressure and temperature after the expansion. However, this significantly boosts expander performance parameters, including output power and isentropic efficiency. With an inlet steam dryness of 0.3, the output power of the single screw expander exceeds 500 kW, and the isentropic efficiency reaches 76.5%. The study outcomes provide reference for the analysis and improvement of thermal characteristics of a two-phase single-screw expander used for geothermal energy total-flow power generation, as well as the optimization of total-flow power generation technology.关键词：geothermal energy;two-phase wet steam;single-screw expander;thermal characteristics52|6|0更新时间：2025-07-28
- 摘要：To achieve the vision of “carbon neutrality” and promote the integration of highway transportation systems and new energy resources, the highway service areas is taken as the research object. Considering four types of load demands, including electricity, cooling, heating, and gas, a comprehensive energy system is developed for highway service areas, incorporating wind and solar power generation methods and power-to-gas equipment. On this basis, a comprehensive energy system optimization scheduling model for highway service areas is established, and the daily forecast of wind and solar power and the daily consumption of multi-energy load are taken as input, and the output of each equipment and the allocation of energy purchased are used as output, taking the lowest total cost as the objective function, considering constraints such as energy balance, equipment safety, and operating status. A genetic sequence quadratic programming fusion optimization algorithm is designed for the scheduling of comprehensive energy systems in highway service areas, and verified using a typical summer day in a service area as an example. The results show that the scheduling system can effectively accommodate renewable energy resources, coordinate the proportion of external electricity purchases and gas purchases, and ultimately reduce costs. The scheduling results obtained using the proposed fusion algorithm outperform those of traditional genetic algorithms and traditional sequential quadratic programming algorithms, with cost reductions of 11.52% and 0.70% respectively. The solving time is only 6.7% of that of traditional genetic algorithms, with improved independence compared to traditional sequential quadratic programming algorithms.关键词：highway service area;new energy resources;genetic algorithm-sequential quadratic programming algorithm;optimize scheduling;power-to-gas98|6|0更新时间：2025-07-28
- 摘要：To enhance the usability and interpretability of risk prediction system, a traffic risk prediction framework based on just-in-time learning(JITL)improved via self-organizing mapping(SOM)is proposed. Firstly, SOM is applied for clustering the data samples and interpreting the clustering features. Then, a sample selection algorithm based on clustering results is used to construct a similar sample set for the data to be tested, and the support vector machine(SVM), which is the base learner, is invoked online to model and output the risk prediction results. Lastly, the model performance is tested using a traffic flow-crash dataset to evaluate interpretability and accuracy. The results show that the area under receiver operating characteristic curve of the SVM model using the SOM-JITL strategy reaches 0.720, which is 17.5% higher than that of the traditional SVM model without the strategy. The SOM-JITL requires less parameter adjustment, and has better usability. In addition, the clustering results of the SOM-JITL accurately identify high-risk scenarios, such as traffic congestion, which is consistent with realistic scenarios and has interpretability. In summary, the SOM-JITL can effectively enhance the performance of the base learner, and endow the model with balance among accuracy, interpretability and usability, facilitating the cost-effective and large-scale deployment of risk prediction systems.关键词：machine learning;risk prediction;usability;interpretability;just-in-time learning;self-organized map71|6|0更新时间：2025-07-28
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0