摘要：
Depletion of fossil fuel resources at a high speed and increasing demand for energy supply for various purposes in today's life integrated with industry has led to collective contemplation for the optimal and maximum utilization of fossil fuels through the implementation of multigeneration systems. In the presented study, a multigeneration system for cooling, power, freshwater, and Hydrogen production is proposed and investigated from exergy, energy, and economic viewpoints through a specific scenario. A case study is performed, revealing that the system can deliver a net output power of 16,251.8 kW, a cooling load of 15,905.0 kW, produce freshwater at a rate of 3.891 kg/s, and generate hydrogen at 0.284 kg/h. The energy and exergy efficiencies of the system are 60.48 % and 32.55 %, respectively. An economic analysis shows a payback period of 0.474 years. A parametric evaluation is performed to perceive the system operation in various conditions. Subsequently, a multi-objective optimization using the MOPSO-LINMAP method is conducted to identify the optimal operating conditions for the system. The optimization results are compared with the case study findings, demonstrating further improvements in performance metrics. The optimized system achieves a slightly higher energy efficiency of 61.62 % and a lower payback period of 0.40 years, underscoring the benefits of the optimization process. This study highlights the potential of the proposed system to efficiently and economically meet the demands for power, hydrogen, cooling, and freshwater in various applications.
期刊：
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing,2024年913:147089 ISSN：0921-5093
通讯作者：
Bin Jiang
作者机构：
[Zhao, Jun; Wu, Shiqin; Yuan, Yueyang] School of Mechanical and Electrical Engineering, Hunan City University, Yiyang, 413002, China;[Xu, Jun] Guangdong Provincial Key Laboratory of Metal Toughening and Application, Institute of New Materials, Guangdong Academy of Sciences, Guangzhou, 510650, China;[Jiang, Bin] National Engineering Research Center for Magnesium Alloys, College of Materials Science and Engineering, Chongqing University, Chongqing, 400044, China;[Chai, Yanfu] School of Mechanical and Electrical Engineering, Shaoxing University, Shaoxing, 312000, China;[Wang, Qinghang] School of Mechanical Engineering, Yangzhou University, Yangzhou, 225127, China
通讯机构：
[Bin Jiang] N;National Engineering Research Center for Magnesium Alloys, College of Materials Science and Engineering, Chongqing University, Chongqing, 400044, China
摘要：
Effects of Sn, Mn, and their combined additions on microstructural characteristic and tensile properties of extruded Mg-1Gd (G1) alloy are explored. Compared to the sole Sn or Mn addition, an excellent grain refining is happened with the Sn and Mn combined addition. The average grain size of G1, Mg-1Gd-0.8Sn (GS10), Mg-1Gd-0.7Mn (GM10) and Mg-1Gd-0.8Sn-0.7Mn (GSM100) alloys is ∼21.3, 10.1, ∼12.8 and ∼6.8 μm, respectively. The sole Mn addition enhances the strength and ductility of G1 alloy. The forming the fine α-Mn particles and grain refining are attributed to the improved properties of GM10 alloy. The sole Sn addition increases the yield strength of G1 alloy along extrusion direction (ED), but it decreases along transverse direction (TD), The inhomogeneous distribution of coarse GdMgSn particles and formation of TD-split texture should play an important role. The combined effects of Sn and Mn additions guarantee high strength-ductility synergy of GSM100 alloy. The GSM100 alloy exhibits the ultimate strength, yield strength and ductility of ∼276, ∼158 MPa and 24.7 % along ED, and ∼253, ∼157 MPa and 17.5 % along TD, respectively. The jointly effect of the fine grains, a lot of fine GdMgSn and α-Mn particles, the texture weakening and Sn solute atom contributes to the enhancement of properties of GSM100 alloy.
摘要：
Our aim with this paper is to model and investigate the vibration and damping of a new hybrid composite shell. The considered composite cylindrical shell includes an FGM anisogrid lattice shell perfectly filled with viscoelastic foams. The modeling of the lattice part composed of spiral and hoop ribs is accomplished according to a global continuous standard based on orthotropic deep shells. The distribution pattern of the metal and ceramic constituents along the lattice ribs is specified by a power law. The homogenizations between ceramic and metal phases within the ribs, as well as between the FGM lattice structure and foam, are governed by the rule of mixtures. Based on the transferred Kelvin-Voigt viscoelastic scheme, the dynamic moduli of the foam portion are acquired. Because viscoelastic foam is a soft material, the higher-order shear deformation shell theory is used to estimate the system's displacement components. After emanating the dynamic equations by Hamilton's principle, the Chebyshev collocation-based semi-numerical method is implemented to detect the system's frequencies and loss factors. The comprehensive results show the role of each composite characteristic in the vibration and damping behavior of the defined structure.
摘要：
The role of a shock generator in the fuel distribution of a scramjet engine is highly significant. In this article, the usage of the erected 3-lobe nozzle in the existence of a shock generator for fuel injection inside a supersonic combustion chamber is fully studied. A three-dimensional model of the extruded 3-lobe nozzle with two altitudes of 4 mm and 2 mm is produced to disclose the importance of the produced vortex upstream/downstream by the usage of the extruded injector. Comprehensive computational analysis is done to investigate the mixing efficiency and fuel diffusion of the proposed jet configuration. Impacts of the coaxial inward air jet on the hydrogen dispersion of the annual extruded 3-lobe injector are also revealed in the present research. The results of the flow structure indicate that the produced vortex upstream of the erected nozzle improves the fuel dispersion behind the hydrogen jet. Our findings show that the effects of injector height are more considerable than the use of an inner air jet for advance of the fuel mixing within the combustor of a scramjet engine.
作者机构：
[Chen, Changqing; Chen, Chang] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Peoples R China.;[Xia, Yunqing; Chen, Changqing; Chen, Chang] Xiangtan Motor Co Ltd, Xiangtan 411201, Peoples R China.;[Tang, Weihua] Hunan Elect Power Design Inst Co LTD, China Energy Engn Grp, Changsha 410007, Peoples R China.
通讯机构：
[Chen, CQ ] H;Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Peoples R China.;Xiangtan Motor Co Ltd, Xiangtan 411201, Peoples R China.
摘要：
In order to solve the problem of frequency modulation power deviation caused by the randomness and fluctuation of wind power outputs, a method of auxiliary wind power frequency modulation capacity allocation based on the data decomposition of a "flywheel + lithium battery" hybrid-energy storage system was proposed. Firstly, the frequency modulation power deviation caused by the uncertainty of wind power is decomposed by the successive variational mode decomposition (SVMD) method, and the mode function is segmented and reconstructed by high and low frequencies. Secondly, a mathematical model is established to maximize the economic benefit of energy storage considering the frequency modulation mileage, and quantum particle swarm optimization is used to solve the target model considering the charging and discharging power of energy storage and the charging state constraints to obtain the optimal hybrid-energy storage configuration. Finally, the simulation results show that, in the step disturbance, the Delta fmax of the hybrid-energy storage mode is reduced by 37.9% and 15.3%, respectively, compared with single-energy storage. Under continuous disturbance conditions, compared with the single-energy storage mode, the Delta fp_v is reduced by 52.73%, 43.72%, 60.71%, and 47.62%, respectively. The frequency fluctuation range is obviously reduced, and the frequency stability is greatly improved.
摘要：
Microstructures and mechanical properties of the extruded Mg-1Nd-1Mn-xZn (NMZ11x, x = 0, 1 and 2 wt.%) alloys were explored. The NMZ110 alloy exhibits a partial dynamically recrystallized (DRXed) microstructure containing fine DRXed grains and coarse unDRXed grains. 1 wt.% Zn addition leads to more uneven distribution microstructure and then becomes uniform microstructure after 2 wt.% Zn addition. This phenomenon is attributed to the altered Mg12Nd particle size and distribution. The volume fractions of Mg12Nd particles were raised with the increase of Zn addition and the distribution of coarse Mg12Nd particles becomes uneven firstly and then evolves uniform. In addition, the texture was continuously strengthened with increasing Zn addition (the basal panel of most grains tilting 40 +/- 5 degrees along the extrusion direction, ED, changed to the basal panel of most grains paralleling to ED, typical strong basal texture). The change of texture characteristics was mainly affinitive with the decreasing concentration of Nd solute in matrix influenced by increasing Mg12Nd particles. The tensile test showed that Zn addition gradually enhanced the tensile strengths of extruded NMZ11x alloy bars, obtaining the highest yield strength of 212 MPa and ultimate tensile strength of 267 MPa (NMZ112). The increasement of strengths was mainly ascribed to Zn solution strengthening, Mg12Nd particle strengthening and texture strengthening. Besides, adding Zn element can reduce the elongation of the NMZ11x alloy bars. This decrease was mainly associated with increasing coarse Mg12Nd particles and the strong basal texture.
摘要：
Traditional grinding, which is predominantly performed with a negative rake angle (NRA), can be transformed into grinding with a positive rake angle (PRA) by employing femtosecond pulsed laser technology to modify the apex angle of the grains to be less than 90 degrees. This innovative approach aims to reduce grinding forces and grinding temperatures while improving the surface quality of typical hard-to-machine materials. To assess the performance of PRA single grain grinding and to investigate the underlying mechanisms, the finite element simulation software ABAQUS 6.14 was employed to model the grinding of Ti6Al4V titanium alloy with a single diamond abrasive grain. The dependence of grinding force and temperature in single grain grinding with a PRA or an NRA under different grinding parameters was studied and compared. PRA and NRA single diamond grain grinding experiments on Ti6Al4V alloy were carried out, with grinding forces measured using a dynamometer and compared with the simulation results. The grinding surface morphology and surface roughness were observed and measured, and a comparison was made between PRA and NRA grinding. The results indicated that in single diamond grain grinding, transforming to a PRA significantly enhances grinding performance, as evidenced by reduced grinding forces, lower temperatures, improved surface morphology, and decreased surface roughness. These findings suggest that PRA single diamond grain grinding offers substantial benefits for the precision machining of hard-to-machine materials, marking a step forward in optimizing surface finishes.
通讯机构：
[Cai, ZH ] H;Hunan City Univ, Coll Mech & Elect Engn, Yiyang 413000, Peoples R China.;Hunan Univ, Coll Elect & Informat Engn, Changsha 410082, Peoples R China.
关键词：
Frequency regulation;SOC segmented feedback inertia control (SSFIC);Maximum frequency differential inertia control (MFDIC);Exponential inertia droop control (EIDC);DC voltage compensation control (DVCC)
摘要：
When DC-side energy storage batteries participate in frequency regulation, inconsistent inertia requirements exist for frequency deterioration and recovery stages. In addition, the frequency regulation power can lead to the DC overvoltage of the DFIG. To address these issues, this paper proposes a voltage suppression strategy (VSS) during multi-stage frequency regulation with the DC-side energy storage batteries. In the frequency deterioration stage, a SOC segmented feedback inertia control (SSFIC) is developed to reduce the frequency change rate. In the frequency recovery stage, to mitigate transient maximum frequency deviation, a maximum frequency differential inertia control (MFDIC) is constructed by incorporating the transient maximum frequency deviation into inertia control coefficient. In the frequency regulation stage, to decrease the steady state frequency deviation and avoid the secondary frequency drop, an exponential inertia droop control (EIDC) is created by considering the droop coefficient as an exponential function of the frequency change rate. To suppress the DC voltage fluctuation, a DC voltage compensation control (DVCC) is presented to transform the active power of SSFIC, MFDIC and EIDC to the d-axis current compensation increment of GSC. Extensive simulation results have proved that the proposed strategy can successfully enhance the frequency regulation and voltage suppression ability.
通讯机构：
[Cai, ZH ] H;Hunan City Univ, Coll Mech & Elect Engn, Yiyang 413000, Peoples R China.;Hunan Univ, Coll Elect & Informat Engn, Changsha 410082, Peoples R China.
关键词：
High voltage ride-through (HVRT);Doubly fed induction generator (DFIG);Differentiate flatness control (DFC);Time-based virtual resistance control (TBVRC);Coefficient backpropagation droop control;(CBDC)
摘要：
With the rapid development of the wind power penetration, the suppression of wind turbine overcurrent becomes a significant challenge for high-voltage ride-through. A nonlinear hybrid flatness control (NHFC) strategy is proposed to reduce overcurrent, shorten overcurrent duration time and provide reactive power support. The control strategy consists of the following three parts: 1) a differentiate flatness control (DFC) strategy is designed for improving the duration time of the overcurrent. 2) a time-based virtual resistance control (TBVRC) strategy, where the resistance is varied with the fault voltage occurrence time, is employed to regulate and suppress the stator and rotor overcurrent. 3) a coefficient backpropagation droop control (CBDC) strategy, obtained by optimum droop coefficient calculation, is developed to provide outstanding reactive power injection for voltage support. Simulation results indicate that the proposed control strategy can effectively suppress overcurrent with less duration time while providing effective reactive power support.
摘要：
Assessing mechanical properties of the respiratory system (Cst) during mechanical ventilation necessitates an end-inspiration flow of zero, which requires an end-inspiratory occlusion maneuver. This lung model study aimed to observe the effect of airflow obstruction on the accuracy of respiratory mechanical properties during pressure-controlled ventilation (PCV) by analyzing dynamic signals. A Hamilton C3 ventilator was attached to a lung simulator that mimics lung mechanics in healthy, acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD) models. PCV and volume-controlled ventilation (VCV) were applied with tidal volume (VT) values of 5.0, 7.0, and 10.0 ml/kg. Performance characteristics and respiratory mechanics were assessed and were calibrated by virtual extrapolation using expiratory time constant (RCexp). During PCV ventilation, drive pressure (DP) was significantly increased in the ARDS model. Peak inspiratory flow (PIF) and peak expiratory flow (PEF) gradually declined with increasing severity of airflow obstruction, while DP, end-inspiration flow (EIF), and inspiratory cycling ratio (EIF/PIF%) increased. Similar estimated values of Crs and airway resistance (Raw) during PCV and VCV ventilation were obtained in healthy adult and mild obstructive models, and the calculated errors did not exceed 5%. An underestimation of Crs and an overestimation of Raw were observed in the severe obstruction model. Using the modified dynamic signal analysis approach, respiratory system properties (Crs and Raw) could be accurately estimated in patients with non-severe airflow obstruction in the PCV mode.
作者：
Chen, Y. J.;Tang, J. X.;Pang, Z.;Yuan, C.;Yue, T. M.
期刊：
Journal of Manufacturing Processes,2024年112:263-272 ISSN：1526-6125
通讯作者：
Chen, Y
作者机构：
[Chen, Y. J.; Chen, Y; Tang, J. X.; Pang, Z.] Dongguan Univ Technol, Dept Mech Engn, Dongguan 523808, Peoples R China.;[Yuan, C.] Hunan City Univ, Coll Mech & Elect Engn, Yiyang 413000, Peoples R China.;[Yue, T. M.] Hong Kong Polytech Univ, Dept Ind & Syst Engn, Adv Mfg Technol Res Ctr, Hong Kong, Peoples R China.
通讯机构：
[Chen, Y ] D;Dongguan Univ Technol, Dept Mech Engn, Dongguan 523808, Peoples R China.
摘要：
Femtosecond laser machining offers high precision and minimal thermal impact, making it a promising technique for processing hard and brittle materials like single-crystal diamonds (SCDs). In this study, the femtosecond laser machining process for SCD material was systematically optimized to improve both machining efficiency and quality. Initial single-factor experiments were conducted to explore the effects of key process parameters—laser power, scanning speed, and number of scans—on machining performance. Subsequently, response surface methodology (RSM)-based experiments designed using the Box–Behnken method were employed to comprehensively refine the process. A regression model was developed to analyze the data, and the interaction effects of the parameters were thoroughly evaluated. The validated model identified an optimal set of parameters, resulting in a significant improvement in machining performance. This research provides a comprehensive framework for optimizing femtosecond laser machining processes, offering valuable insights critical for the production of advanced lightweight components in industries such as aerospace, optical instruments, and high-performance electronics.
摘要：
<jats:title>Abstract</jats:title><jats:sec>
<jats:title>Background</jats:title>
<jats:p>Respiratory mechanics monitoring provides useful information for guiding mechanical ventilation, but many measuring methods are inappropriate for awake patients. This study aimed to evaluate the accuracy of dynamic mechanics estimation using expiratory time constant (RC<jats:sub>exp</jats:sub>) calculation during noninvasivepressure support ventilation (PSV) with air leak in different lung models.</jats:p>
</jats:sec><jats:sec>
<jats:title>Methods</jats:title>
<jats:p>A Respironics V60 ventilator was connected to an active breathing simulator for modeling five profiles: normal adult, restrictive, mildly and severely obstructive, and mixed obstructive/restrictive. Inspiratory pressure support was adjusted to maintain tidal volumes (V<jats:sub>T</jats:sub>), achieving 5.0, 7.0, and 10.0ml/kg body weight. PEEP was set at 5 cmH<jats:sub>2</jats:sub>O, and the back-up rate was 10bpm. Measurements were conducted at system leaks of 25–28L/min. RC<jats:sub>exp</jats:sub> was estimated from the ratio at 75% exhaled V<jats:sub>T</jats:sub> and flow rate, which was then used to determine respiratory system compliance (C<jats:sub>rs</jats:sub>) and airway resistance (R<jats:sub>aw</jats:sub>).</jats:p>
</jats:sec><jats:sec>
<jats:title>Results</jats:title>
<jats:p>In non-obstructive conditions (R<jats:sub>aw</jats:sub> ≤ 10 cmH<jats:sub>2</jats:sub>O/L/s), the C<jats:sub>rs</jats:sub> was overestimated in the PSV mode. Peak inspiratory and expiratory flow and V<jats:sub>T</jats:sub> increased with PS levels, as calculated C<jats:sub>rs</jats:sub> decreased. In passive breathing, the difference of C<jats:sub>rs</jats:sub> between different V<jats:sub>T</jats:sub> was no significant. Underestimations of inspiratory resistance and expiratory resistance were observed at V<jats:sub>T</jats:sub> of 5.0ml/kg. The difference was minimal at V<jats:sub>T</jats:sub> of 7.0ml/kg. During non-invasive PSV, the estimation of airway resistance with the RC<jats:sub>exp</jats:sub> method was accurately at V<jats:sub>T</jats:sub> of 7.0ml/kg.</jats:p>
</jats:sec><jats:sec>
<jats:title>Conclusions</jats:title>
<jats:p>The difference between the calculated C<jats:sub>rs</jats:sub> and the preset value was influenced by the volume, status and inspiratory effort in spontaneously breathing.</jats:p>
</jats:sec>
