摘要：
Dew-point indirect evaporative cooling (DPIEC) technology is designed and applied as a low carbon-emission and high energy-efficient air conditioning (AC) solution without employing non-environmentally friendly refrigerant and mechanical compressor for cooling in building sector. A more realistic three-dimensional (3-D) model of the DPIEC that better captures the fundamental thermodynamic of its operation is proposed. It considers the variability of air thermal properties and is employed to investigate the DPIEC's performance for three possible arrangements. The 3-D model is classified as configurations 1, 2 and 3 based on the relative flow direction between primary/secondary air and spray water. Experimental results indicate that the model can well evaluate the thermodynamic performance. Additionally, the influence of crucial factors on the performance is parametrically studied by employing three performance indexes. Comparison reveals that configuration 1 can achieve the highest effectiveness and cooling capacity. Results also show that the secondary-to-primary air ratio should be confined to around 0.3 to achieve maximum cooling capacity, and the optimal channel gap should be limited to the range from 3 to 4 mm. Comparatively, the relative flow direction between the spray water and the primary/secondary air has a greater effect on the thermodynamic performance than the spray water inlet velocity.
摘要：
The modulation mechanism of iron (Fe) and manganese (Mn) in transition-metal elements on the interface bonding and mechanical properties of bronze (Cu3Sn)-based/diamond composites is investigated through first-principles calculations. Transition-elements-doping scenarios are investigated employing six-layer slab models. It is revealed that the doping of Fe or Mn can make the Cu3Sn/diamond interface more stable, which effectively improves the wettability of the Cu3Sn/diamond interface based on the calculation results and analysis of interface energy, differential charge density model, and density of states. However, co-doping with both Fe and Mn weakens the wettability of the Cu3Sn/diamond interface. Finally, wettability tests and microstructure characterizations demonstrate that the doping of Fe and Mn represents an effective approach to controlling the interface bonding performance of bronze/diamond composites. Fe- and Mn-doping effects on the interface binding and mechanical properties of Cu3Sn/diamond composites are studied using first-principles calculations. Analysis of interface energy, charge density models, and density of states reveals that individual Fe or Mn doping improves Cu3Sn//diamond interface wettability. Conversely, co-doping weakens Cu3Sn/diamond interface wettability. Wettability tests and microscopic characterization validate these findings.image (c) 2023 WILEY-VCH GmbH
摘要：
Exploring the single relationship between the inversion degree of spinel and its catalytic performance is a great challenge, but has important significance for further structural design and application. A series of CoMn inverse spinels were prepared and the general formula (Co-1-x(2+) Co-x(3+)) (tet) (Mn-1(3+) Co-x(2+) Co-1-x(3+))(oct)O-4 was deduced through X-ray diffraction refinement to find a decreased inversion degree x as calcination temperature rose. Catalytic oxidation of toluene showed that higher inversion degree (S-300 with x approximate to 0.95) can reach larger conversion rate (90 % at about 250 degrees C for 400 ppm toluene) with greater reaction stability (140 h). Density Functional Theory (DFT) calculations on density of states indicated its metallic nature, and found that the strength of O-p and Transition metal-d orbitals at Fermi energy is positively correlated to the inversion degree, meaning stronger electron migration ability. Along with the adsorption calculation analysis that lattice oxygen species are proved to work dominantly (S-300 with lowest adsorption energy but highest performance), this work uncovered a theoretical insight into inverse spinel oxide, to provide the possibility of elevated oxidation ability through structural control.
摘要：
The anisotropic behavior of as-extruded 7003 aluminum alloy under quasi-static compression and high-speed impact was studied using samples with axes parallel to extrusion direction (ED) (0 degrees sample), at an angle of 45 degrees to ED (45 degrees sample), and perpendicular to ED (90 degrees sample). The experimental results show that the yield stress of the 0 degrees sample is the highest, while the 45 degrees sample is the lowest. Compared with other samples, the 90 degrees sample is more sensitive to the applied strain rate, which experiences a rapid failure after reaching peak stress under high-speed impact. Under quasi-static compression and high-speed impact, the 0 degrees sample exhibits nearly uniform deformation, while the 45 degrees and 90 degrees samples exhibit anisotropy behavior. Due to the occurrence of adiabatic shear, the plastic deformation anisotropy in 45 degrees and 90 degrees samples under high-speed impact is more significant compared to quasi-static compression. For the 45 degrees and 90 degrees samples, the r values, which characterize plastic deformation anisotropy, decrease from 0.77 to 0.82 under quasi-static compression to 0.46 and 0.40 under high-speed impact. In addition, adiabatic shear bands are observed in all deformed samples under highspeed impact, while only the 90 degrees sample fractures. Due to the significant difference in Schmidt factors along ED and transverse direction (TD), plastic deformation of the 90 degrees sample under high-speed impact is mainly concentrated in TD, while the deformation in ED is very small. The extremely uneven deformation leads to earlier nucleation and faster development of ASBs in TD, causing the 90 degrees sample to fracture under high-speed impact.
摘要：
Thus far, the available works on sequencing flexibility in shop floor scheduling only consider the sequencing flexibility with serial operation constraint. However, the sequencing flexibility with discrete and hybrid operation constraints are also widely existed in the actual production and have significant impact on production efficiency. Therefore, this work proposes a distributed flexible job shop scheduling problem considering integrated sequencing flexibility (DFJSPS), in which the serial, discrete and hybrid operation constraints are considered simultaneously. A mixed integer linear programming model is proposed to solve the DFJSPS by using the CPLEX solver. Then, an efficient memetic algorithm (EMA) is designed with the objectives of minimizing makespan and total energy consumption. In the EMA, a five-layer coding method and an efficient initialization method are presented to obtain high quality initial solutions; and an efficient local search operator is designed to help the algorithm to improve its convergence speed. Comprehensive experiments show that the EMA outperforms other three well-known algorithms in most of the instances, demonstrating the superior performance of EMA for solving DFJSPS in terms of both computational efficiency and solution quality. In summary, the research fills the research gap on integrated sequencing flexibility in the field of shop floor scheduling; on the other hand, it can help production managers to obtain the efficient scheduling schemas in the decision-making systems about various types of sequencing flexibility.
通讯机构：
[Ma, YL ] C;Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Peoples R China.
关键词：
Joint denoising;Improved quaternion singular value decomposition;Fault diagnosis;Gear
摘要：
Singular value decomposition (SVD) has drawn increasing attention in recent years as an effective signal noise reduction method. However, it is inapplicable to multivariate signals with abundant fault information. Existing quaternion singular value decomposition (QSVD) can decompose multivariate signals simultaneously, but the methods based on QSVD dependent on the embedding dimension and reconstructed components order seriously, and they are not suitable to noisy signals. To solve the problem, a novel joint denoising method improved quaternion singular value decomposition (IQSVD) is proposed, which can determine two parameters adaptively. Firstly, to select the embedding dimension, the improved power spectral density (IPSD) is proposed with considering frequency features and time -domine traits together. And then the periodic intensity (PI) is used to determine the reconstructed components by searching the component composing the most abundant periodic part. Finally, combined with envelope spectrum analysis, the gear fault is diagnosed. The results of the gear simulated and experimental multivariate signals verify the effectiveness of proposed method.
摘要：
The hydrogen addition to liquid methane gas (LMG) engines based on the rational control strategy is considered to be a promising approach to improve the performance of LMG engines. However, the current studies are limited to a few operating points. To comprehensively develop a control strategy of hydrogen addition for high compression ratio LMG engines, the effects of hydrogen addition on the emissions, combustion, and performance of an LMG engine are experimentally investigated under all operating conditions in this study. Furthermore, to achieve the optimal performance of the hydrogen-LMG engine with the optimal hydrogen blending, the coupled simulation model of MATLAB/Simulink and GT-Power is established based on the test bench, and the multiple operating parameters of the calibrated numerical model are optimized by using genetic algorithm. The results show that the maximum increases in the brake thermal efficiency with increasing hydrogen energy share (HES) are 1.6, 0.9 and 0.6 percentage points under low, medium and high loads, respectively. Correspondingly, the maximum reduction in EBSFC under low, medium and high loads is 6.5 %, 2.2 % and 1.4 %, respectively. The ignition delay is reduced and the combustion is promoted with the increase in HES. As a result, the cylinder pressure and HRR rise faster and reach a higher peak earlier. In addition, the 50 % combustion location is advanced and the 10-90 % combustion duration is shortened. In terms of emissions, the increasing HES promotes the NOx emissions and reduces the HC emissions. Especially at medium and high loads, the NOx emissions rise sharply with increasing HES. It is desirable that HES should not exceed 15 %, 4 % and 2 % at low, medium and high loads, respectively. In addition, by co-optimizing the intake valve opening timing, exhaust valve opening timing and the spark angle, the BSFC of the hydrogen-LMG engine with the optimal HES under 1200 rpm and BMEP of 6 bar is still improved by 2.2 %. This study provides new insights to further explore the energy-saving potential of hydrogen-LMG engines.
作者机构：
[Zhou, Feng; Zhou, F; Yu, Juan; Zeng, Wen] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Peoples R China.;[Fu, Jianqin; Zhou, Feng; Liu, Jingping] Hunan Univ, State Key Lab Adv Design & Mfg Vehicle Body, Changsha 410082, Peoples R China.;[Yuan, Kainan] China Machinery Int Engn Design & Res Inst Co Ltd, Changsha 410000, Hunan, Peoples R China.
通讯机构：
[Zhou, F ] C;Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Peoples R China.
关键词：
Deep neural networks;Hyperparameter optimization;NO X prediction;Transient cycle;Diesel engine;Population based training
摘要：
Due to the rising environmental concerns, particularly air quality, the emission regulations for non -road mobile machinery are becoming increasingly strict. Real-time emission prediction from diesel engines is significant for emission control and regional pollution estimation. This study aims to develop a machine learning model and optimize its hyperparameters by using a hyperparameter optimization method to NOX emission. Firstly, we collected NOX emission data from test under the non -road transient test cycle (NRTC) and built a significant dataset to choose a best model. Then, the model was trained by dataset and the hyperparameters were automatically optimized by combining Bayesian and Population based training. The accuracy of the optimized was indicated by an R2 value of 0.9784 with the 8 input features. The relative error in the cycle level was 1.3%. Lastly, the quality of NOX emissions during the cycle and the effect of each parameter on NOX emissions were analyzed. The results show that the model is able to predict the real-time concentration changes of NOX more accurately. It can provide a reference for the research and development of emission control technology for nonroad mobile machinery.
摘要：
In this paper, the combustion, heat-work conversion process and emission characteristic at high compression ratio for the spark ignition engine fuelled with E20 (20 % ethanol, 80 % gasoline) fuel were investigated under ultra-lean burn conditions. Specifically, the direct injection (DI) mode combined with port fuel injection (PFI) mode strategy was used in the experiments. In addition, the dual injection strategies were comprehensively investigated by using different fuel injection masses and injection timing. The results indicated that using optimal injection timing and reasonable injection masses can improve heat-work conversion efficiency and combustion efficiency, combustion stability in the test engine. Furthermore, under the lean combustion model, using earlier injection timing could not only inhibit the soot production, but also decrease the nitrogen oxides formation. Compared to the equivalence ratio at 0.82 and DI injection timing at 120 degrees CA bTDC, soot and NOX emissions were respectively reduced by 14.93 %-26.6 % and 39.84 %-73.56 % under the equivalence ratio at 0.685 and DI injection timing at 180 degrees CA bTDC. This study provides an optimization direction for the application of ethanolgasoline blends in the internal combustion engine (ICE) engines for high efficiency and clean combustion.
摘要：
The passive pre-chamber exhibits great potential for practical applications in the internal combustion engine due to its simple structure. However, it faces difficulties in scavenging process, making optimization of pre-chamber structure particularly important. In this study, the effects of pre-chamber ignition systems with different structures and original spark ignition were conducted on a high compression ratio direct-injection SI engine to investigate the combustion, performance, and emission characteristics. The results show that the increase in prechamber volume weakens the in-cylinder combustion process and engine performance, while increasing the prechamber orifice diameter can enhance the combustion stability at medium to high loads, but will weaken the engine performance at low load. Compared to spark ignition, pre-chamber ignition results in an earlier 50% combustion position, a shorter combustion duration and lower COVIMEP, with these effects becoming stronger as load increases. At high load, the pre-chamber ignition (PC1) advances the 50% combustion position by 5.6 degrees CA and shortens the combustion duration by 16.7%. In addition, the indicated thermal efficiency of the pre-chamber ignition achieves an increase of 0.84% at the optimal point and 2.5% at high load. Overall, using the smaller orifice diameter and volume in the pre-chamber can improve in-cylinder combustion process and increase thermal efficiency across the load range. For emission analysis, the pre-chamber ignition leads to an increase in NOx and HC emissions due to the influence of in-cylinder combustion temperature and quenching effect, while the CO emissions are similar to spark ignition.
期刊：
Science of The Total Environment,2024年913:169708 ISSN：0048-9697
通讯作者：
Duan, XB
作者机构：
[Zhou, Feng; Yu, Juan; Wu, Chenghao] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Peoples R China.;[Fu, Jianqin; Zhou, Feng; Liu, Jingping; Duan, Xiongbo] Hunan Univ, Coll Mech & Vehicle Engn, Changsha 410082, Peoples R China.;[Duan, XB; Duan, Xiongbo] Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.
通讯机构：
[Duan, XB ] C;Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.
关键词：
Cold start;Combustion;Low carbon fuel;Methanol engine;Regulated and unregulated emissions;Renewable fuel
摘要：
In the context of global carbon neutrality, the internal combustion engines aim to further reduce the carbon emission and improve the fuel economy for the transportation sector. Methanol is treated as a renewable, reliability, and applicability energy, which also shows some superior physicochemical properties compared to the traditional fossil fuels. However, some challenges such as cold start issue, low fuel economy, high unregulated emissions need to address before the methanol widely applies in the engines. This article comprehensively reviews the physicochemical properties and production processes of the methanol, the cold start issue of the methanol engine, and emission and combustion characteristics of the methanol engine for evaluating its potential effect of emission reduction and energy saving in the transportation sector. In addition, different optimization strategies and advanced technologies are proposed and comprehensively discussed in this paper for addressing the issues of the cold start, combustion and emissions of the methanol engines in the real application. Finally, the conclusions and prospects of the methanol engine are presented for promoting its application in the transportation sector and further reducing the carbon emission in the near future, thereby achieving the carbon peak and carbon neutrality in the China.
期刊：
Chemical Engineering Journal,2024年485:149913 ISSN：1385-8947
通讯作者：
Fangjian Ning<&wdkj&>Hailong Peng
作者机构：
[Rui Sheng; Yue Liu; Taimei Cai; Rong Wang; Hailong Peng] School of Chemistry and Chemical Engineering, Nanchang University, Nanchang 330031, China;[Gan Yang; Tao Wen] School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha, Hunan 410004, China;[Fangjian Ning] China Food Flavor and Nutrition Health Innovation Center, Beijing Technology and Business University, Beijing 100048, China
通讯机构：
[Fangjian Ning] C;[Hailong Peng] S;China Food Flavor and Nutrition Health Innovation Center, Beijing Technology and Business University, Beijing 100048, China<&wdkj&>School of Chemistry and Chemical Engineering, Nanchang University, Nanchang 330031, China
摘要：
Point–of–care testing (POCT) plays vital role in clinic field, especially in resource–limited areas. The nanozyme–based colorimetric platform is the potential strategy for POCT. Therefore, a high–entropy allay nanozyme (HEAzyme) was prepared via formaldehyde–assisted metal–ligand crosslinking method using multi–metal (FeCuAgCeGd) species. The obtained FeCuAgCeGd–HEAzyme showed coordination nanoparticles with ultrafine size (average size was approximately 5 nm). The peroxidase–like (POD–like) activity of FeCuAgCeGd–HEAzyme was verified through density functional theory (DFT) calculations, demonstrating the capability of FeCuAgCeGd–HEAzyme to catalyze H2O2 and generate hydroxyl radicals (•OH). These radicals can oxidize colorless 3,3′,5,5′–tetramethylbenzidine (TMB) to blue oxTMB. Dopamine (DA) scavenges •OH, resulting in an “on–off” effect for TMB oxidation. Subsequently, an FeCuAgCeGd–HEAzyme colorimetric sensor was developed for DA detection, which features a low detection limit of 0.77 µM and a linear range of 5.0–70.0 µM. The sensor demonstrated a recovery ratio in spiked serum samples ranging from 97.7 % to 104.3 % with high stability and favorable selectivity. Furthermore, an FeCuAgCeGd–HEAzyme POCT platform was designed for on–site detection of DA, achieving a reliable linear detection range (5.0–70.0 µM) and a low detection limit (5.69 µM). This platform offers a facile and efficient strategy for rapid, visual, and on–site DA detection in clinical settings with advantages of cost–effectiveness and ease of operation.
摘要：
The cutting vibration generated by cutting forces is critical to the accuracy and efficiency of face-hobbed hypoid gears. However, few relevant works are currently on cutting dynamics modeling for the face-hobbing process due to its complex spatial relationships. This study developed an efficient cutting dynamics model considering comprehensive characteristics of the non-generated face-hobbed hypoid gear machining process. A concise and efficient analytical solution to cutting dynamics modeling for face-hobbing of hypoid gears is obtained by using a vectorization method to characterize chip regenerating mechanisms. The machine tool vibration caused by cutting forces is predicted and validated according to an industrial case study. The proposed cutting dynamic model is 36.11% more efficient than the semi-analytical dynamic model derived from other cutting force prediction methods, and its accuracy is also improved with an error of less than 15%. Furthermore, the proposed vectorization solution to face-hobbing cutting dynamics modeling will be a practicable and effective method for analyzing the chatter in the machining of complex surfaces.
摘要：
Previous studies on production scheduling predominantly focus on developing optimal production plans in the context of deterministic customer requirements, achieving certain optimization goals related to the manufacturer. However, little research has been conducted on scheduling customized spare parts manufacturing on the supply side and equipment operation strategy on the demand side simultaneously. In real-world engineering projects, an efficient collaborative scheduling solution not only helps the manufacturer develop optimal production plans for critical spare parts, but also guides equipment users to achieve maximum output. Therefore, this paper studies a collaborative scheduling problem that both considers energy-saving spare parts manufacturing in a flexible job shop and equipment operation strategy of distributed users. To solve this problem effectively, a self-adaptive two-stage memetic algorithm (STMA) is proposed to minizine total energy consumption of the manufacturer and maximize total operation utility of equipment simultaneously. In detail, four heuristic rules are designed to generate a high-quality initial population. In the first stage, the crossover and mutation are utilized for global exploration, and a self-adaptive local search operator is presented to enhance the local development ability of the STMA. In the second stage, several energy-saving and utility-improving strategies are proposed to further optimize the Pareto front solutions generated in the previous period. Extensive experiments are conducted, and the numerical results indicate that STMA is the most promising compared to other well-known algorithms.
期刊：
Separation and Purification Technology,2024年334:126093 ISSN：1383-5866
通讯作者：
Ma, XC;Li, LQ;Su, RK
作者机构：
[Ma, Xiancheng; Xu, Wenjun] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Li, Liqing; Li, LQ; Zeng, Zheng; Guo, Yang] Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Su, Rongkui; Wang, Hanqing; Su, RK] Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Zhou, Yihui] Aerosp Kaitian Environm Technol Co Ltd, Changsha 410100, Hunan, Peoples R China.
通讯机构：
[Li, LQ ; Su, RK ; Ma, XC ] C;Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China.;Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410083, Hunan, Peoples R China.
关键词：
Porous carbon;Acetone and methanol adsorption;Azeotrope separation;Pore structure;Nitrogen and oxygen groups
摘要：
The adsorption and separation of methanol and acetone are crucial for environmental protection and recycling. However, the separation of methanol and acetone azeotropes using carbon-based materials remains challenging, and the underlying mechanism is still unclear. Here, we propose the synthesis of porous carbon (NaOCs) using benzimidazole as a precursor and NaOH as an activator. With the increase of the proportion of NaOH and benzimidazole, the activation reaction was intensified, leading to the formation of numerous mesopores. NaOCs exhibit a maximum specific surface area (SBET) of 3084 m2/g, and has extremely high adsorption capacity of methanol (56.9 mmol/g at 13 kPa) and acetone (34.6 mmol/g at 18 kPa) at 25 degrees C. The results of experiments and molecular simulations indicate that the saturation adsorption capacity of methanol and acetone is determined by micropores and narrow mesopores at 25 degrees C, whereas the adsorption capacity at relatively low pressure is primary determined by ultramicropores and oxygen group. Furthermore, for methanol-acetone azeotropes separation, the acetone/methanol selectivity at low pressure depends on carbon surface polarity and ultramicropore, while methanol/acetone selectivity at high pressure depends on micropores of 1-2 nm. Our findings provide insights into the design and further development of adsorbents for VOCs adsorption and azeotrope separation applications.
摘要：
Order cancellation, due to such as customer plan adjustments or market changes, usually occurs in the real production environment of distributed flexible job shop scheduling problem (DFJSP). However, thus far, all exiting researches about DFJSP have not consider order cancellation, which normally leads to resource waste and makes the original scheme infeasible. Hence, in this work, we propose a DFJSP considering order cancellation (DFJSPC) for the first time; and design a reformative memetic algorithm (RMA) to solve the DFJSPC aiming at optimizing the makespan and total energy consumption. In the RMA, a five-layer encoding operator and a new load balancing initialization method are designed to improve the quality of the initial population. Some effective crossover, mutation and local search operators are designed, which can fully expand the solution space of the algorithm and improve its convergence speed. A total of 60 DFJSPC benchmark instances are constructed, and some comparative experiments are carried out among the proposed RMA and three well-known algorithms, namely NNIA, NSGA-II and NSGA-III. The final experimental results verified the outstanding performance of the RMA. This research will provide a theoretical basis for the order cancellation problem in distributed production settings, and help manufacturers to properly handle canceled orders to reduce resource waste and reschedule the infeasible schemes causing from order cancellation.
