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Study of Flow and Heat Transfer in an Ejector-Driven Swirl Anti-Icing Chamber

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Fluid Dynamics & Materials Processing 2024年第5期20卷 989-1014页

作者： Yi tu Yuan Wu Yu Zeng Hunan University of Arts and Sciences Hunan Key Laboratory of Distributed Electric Propulsion Vehicle Control TechnologyChangde415000China Liaoning Provincial Key Laboratory of Aircraft Ice Protection AVIC Aerodynamics Research InstituteShenyang110034China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic *** Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent *** study employs a validated Computational Fluid Dynamics(CFD)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing ***,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the *** research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI ***,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy *** nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI ***θfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.

关键词： Swirl anti-icing heat transfer exergy efficiency hot and cold spot aircraft engine

A Novel Defender-Attacker-Defender Model for Resilient Distributed Generator Planning with Network Reconfiguration and Demand Response

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Energy Engineering 2024年第5期121卷 1223-1243页

作者： wenlu Ji Teng tu Nan Ma Nanjing Power Supply Company State Grid Jiangsu Electric Power Co.Ltd.Nanjing210019China

To improve the resilience of a distribution system against extreme weather,a fuel-based distributed generator(DG)allocation model is proposed in this *** this model,the DGs are placed at the planning *** an extreme event occurs,the controllable generators form temporary microgrids(MGs)to restore the load ***,a demand response program(DRP)mitigates the imbalance between the power supply and demand during extreme *** cope with the fault uncertainty,a robust optimization(RO)method is applied to reduce the long-term investment and short-term operation *** optimization is formulated as a tri-level defenderattacker-defender(DAD)*** the first level,decision-makers work out the DG allocation scheme;at the second level,the attacker finds the optimal attack strategy with maximum damage;and at the third level,restoration measures,namely distribution network reconfiguration(DNR)and demand response are *** problem is solved by the nested column and constraint generation(NC&CG)method and the model is validated using an IEEE 33-node *** studies validate the effectiveness and superiority of the proposed model according to the enhanced resilience and reduced cost.

关键词： Distribution system resilience defender-attacker-defender distributed generator demand response microgrids formation

In situ photocatalytically enhanced thermogalvanic cells for electricity and hydrogen production

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Chinese Journal of Structural Chemistry 2024年第1期43卷 1-2页

作者： Tianhao Li wenguang tu Zhigang Zou School of Science and Engineering The Chinese University of Hong KongShenzhenGuangdong518172PR China

Converting low-grade thermal energy into electricity through ther-mogalvanic cells offers a promising approach to addressing environ-mental challenges[1].However,thermogalvanic cells face obstacles,due to limited thermopower,connected to differences in solvent-dependent entropy(ΔS)among redox anions and varying concentration ratios(ΔC)between hot and cold sides[2,3].A typical strategy to enhance the thermopower involves the improvement ofΔS of the redox ***-fortunately,ΔC tends to approach zero spontaneously due to the ther-modynamic instability and redox ion ***,the challenge is to maintain significantΔC for both redox ions and unravel the intricate modulation mechanisms[4].

关键词： redox maintain entropy

Selective control of secondary alcohols upgrading using Ir-catalyzed cross-coupling strategy

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Science China Chemistry 2024年第3期67卷 914-921页

作者： Siqi Yang Zeye Lu Jiale Ji Qingshu Zheng Tao tu Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Department of ChemistryFudan UniversityShanghai 200438China Frontiers Science Center for Transformative Molecules School of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

The selective coupling of alcohols is a fascinating yet challenging approach for upgrading alcohols. Herein, we accomplished the controlled production of β-disubstituted ketones or upgraded secondary alcohols via the Ir-catalyzed cross-coupling of secondary alcohols in excellent yields with broad substrate scopes. This selective control was achieved by using an in-situ generated monoNHC-Ir or a tris-NHC-Ir complex as the catalysts, respectively. Mechanistic studies revealed that the delicate balance between dehydrogenation and hydrogenation abilities of these bifunctional catalysts is crucial for achieving different selectivity. The tris-NHC-Ir complex effectively facilitated dehydrogenation of alcohols and hydrogenation of intermediates, leading to the desired upgraded secondary alcohols. Conversely, the high dehydrogenation ability of the mono-NHC-Ir complex promoted the conversion of formed secondary alcohols back to ketones.

关键词： cross-coupling hydrogen-borrowing NHC-Ir complexes selectivity control upgrading of alcohols

Valorization of carbon dioxide with alcohols

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Chinese Chemical Letters 2024年第7期35卷 54-58页

作者： Daheng wen weiwei Fang Yongmei Liu Tao tu Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Department of ChemistryFudan UniversityShanghai 200438China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Utilizing CO_(2)for the production of bulky and valuable chemicals presents an attractive solution to address environmental and fossil energy *** the various approaches,direct carboxylation of alcohols with CO_(2)stands out as an eco-friendly process capable of efficiently producing carboxylic acids in a sustainable ***,the high dissociation energy of the C–O bond poses a significant challenge in this *** the past few decades,several strategies have been developed to activate alcohols and establish efficient catalytic systems for carboxylation with CO_(2).Nevertheless,the sporadic nature of reported approaches makes it difficult to determine the most effective *** perspective aims to provide an overview of the current state-of-the-art catalytic protocols for carboxylating alcohols with CO_(2),encompassing esterification,halogenation,and photocatalysis,while considering their respective advantages and *** aim to discern the most promising avenues for future development in this *** insights presented in this perspective will contribute to the advancement of efficient and sustainable carboxylation methods using CO_(2),leading to the production of valuable chemicals in future.

关键词： Carboxylation Carbon dioxide Alcohol Carboxylic acid Transition metal catalysis

Machine learning-driven optimization of plasma-catalytic dry reforming of methane

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Journal of Energy Chemistry 2024年第9期96卷 153-163页

作者： Yuxiang Cai Danhua Mei Yanzhen Chen Annemie Bogaerts Xin tu Department of Electrical Engineering and Electronics University of LiverpoolLiverpool L693GJUK Research Group PLASMANT Department of ChemistryUniversity of AntwerpUniversiteitsplein 1BE-2610 Wilrijk-AntwerpBelgium College of Electrical Engineering and Control Science Nanjing Tech UniversityNanjing 211816JiangsuChina

This study investigates the dry reformation of methane(DRM)over Ni/Al_(2)O_(3)catalysts in a dielectric barrier discharge(DBD)non-thermal plasma reactor.A novel hybrid machine learning(ML)model is developed to optimize the plasma-catalytic DRM reaction with limited experimental *** address the non-linear and complex nature of the plasma-catalytic DRM process,the hybrid ML model integrates three well-established algorithms:regression trees,support vector regression,and artificial neural networks.A genetic algorithm(GA)is then used to optimize the hyperparameters of each algorithm within the hybrid ML *** ML model achieved excellent agreement with the experimental data,demonstrating its efficacy in accurately predicting and optimizing the DRM *** model was subsequently used to investigate the impact of various operating parameters on the plasma-catalytic DRM *** found that the optimal discharge power(20 W),CO_(2)/CH_(4)molar ratio(1.5),and Ni loading(7.8 wt%)resulted in the maximum energy yield at a total flow rate of∼51 mL/***,we investigated the relative significance of each operating parameter on the performance of the plasma-catalytic DRM *** results show that the total flow rate had the greatest influence on the conversion,with a significance exceeding 35%for each output,while the Ni loading had the least impact on the overall reaction *** hybrid model demonstrates a remarkable ability to extract valuable insights from limited datasets,enabling the development and optimization of more efficient and selective plasma-catalytic chemical processes.

关键词： Plasma catalysis Machine learning Process optimization Dry reforming of methane Syngas production

Non-cooperative Game Based Optimal Dispatch Model for Integrated Energy Systems

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1195-1207页

作者： Jiandong Duan Qian Sun Chen Wu Yao Yang Siyu tu School of Electrical Engineering Xi’an University of TechnologyXi’an710056China IEEE CSEE

In order to improve the efficiency of energy utilization,the integrated energy system(IES)has *** IES typically acts as a whole system during operations,the subsystems are separated,and the interests of each system are *** this paper,considering the relationship between the various energy systems,non-cooperative game theory is used to establish the optimal dispatch *** proposed model mainly relies on the relationship between the cooperation and competition among various subsystems to obtain the maximum benefit they can ***,the basic definition is combined with the particle swarm optimization algorithm to solve the *** results show that the optimization strategy proposed in this paper can operate safely and reliably,and effectively distribute the benefits of each energy system.

关键词： Integrated energy system multi-energy complimentarily non-cooperative game theory

SWG: an architecture for sparse weight gradient computation

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Science China(Information Sciences) 2024年第2期67卷 302-321页

作者： weiwei WU Fengbin tu Xiangyu LI Shaojun weI Shouyi YIN School of Integrated Circuits Tsinghua University Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology

On-device training for deep neural networks(DNN) has become a trend due to various user preferences and scenarios. The DNN training process consists of three phases, feedforward(FF), backpropagation(BP), and weight gradient(WG) update. WG takes about one-third of the computation in the whole training process. Current training accelerators usually ignore the special computation property of WG and process it in a way similar to FF/BP. Besides, the extensive data sparsity existing in WG, which brings opportunities to save computation, is not well explored. Nevertheless, exploiting the optimization opportunities would meet three underutilization problems, which are caused by(1) the mismatch between WG data dimensions and hardware parallelism,(2) the full sparsity, i.e., the sparsity of feature map(Fmap),error map(Emap), and gradient, and(3) the workload imbalance resulting from irregular sparsity. In this paper, we propose a specific architecture for sparse weight gradient(SWG) computation. The architecture is designed based on hierarchical unrolling and sparsity-aware(HUSA) dataflow to exploit the optimization opportunities of the special computation property and full data sparsity. In HUSA dataflow, the data dimensions are unrolled hierarchically on the hardware architecture. A valid-data trace(VDT) mechanism is embedded in the dataflow to avoid the underutilization caused by the two-sided input sparsity. The gradient is unrolled in PE to alleviate the underutilization induced by output sparsity while maintaining the data reuse opportunities. Besides, we design an intra-and inter-column balancer(IIBLC) to dynamically tackle the workload imbalance problem resulting from the irregular sparsity. Experimental results show that with HUSA dataflow exploiting the full sparsity, SWG achieves a speedup of 12.23× over state-of-the-art gradient computation architecture, Train Ware. SWG helps to improve the energy efficiency of the state-of-the-art training accelerator LNPU from

关键词： CNN training gradient computation sparsity architecture

China stroke surveillance report 2021

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Military Medical Research 2024年第3期11卷 374-399页

作者： wen-Jun tu Long-De Wang 无 Department of Neurosurgery Beijing Tiantan HospitalCapital Medical UniversityBeijing 100070China School of Public Health Peking UniversityBeijing 100191China Special Writing Group of China Stroke Surveillance Report

Since 2015,stroke has become the leading cause of death and disability in China,posing a significant threat to the health of its citizens as a major chronic non-communicable *** to the China Stroke High-risk Population Screening and Intervention Program,an estimated 17.8 million[95%confidence interval(CI)17.6–18.0million]adults in China had experienced a stroke in 2020,with 3.4 million(95%CI 3.3–3.5 million)experiencing their first-ever stroke and another 2.3 million(95%CI 2.2–2.4 million)dying as a ***,approximately 12.5%(95%CI 12.4%–12.5%)of stroke survivors were left disabled,as defined by a modified Rankin Scale score greater than 1,equating to 2.2 million(95%CI 2.1–2.2 million)stroke-related disabilities in *** the population ages and the prevalence of risk factors like diabetes,hypertension,and hyperlipidemia continues to rise and remains poorly controlled,the burden of stroke in China is also increasing.A large national epidemiological survey initiated by the China Hypertension League in 2017 showed that the prevalence of hypertension was 24.7%;the awareness,treatment,and control rates in hypertensive patients were:60.1%,42.5%,and 25.4%,respectively.A nationally representative sample of the Chinese mainland population showed that the weighted prevalence of total diabetes diagnosed by the American Diabetes Association criteria was 12.8%,suggesting there are 120 million adults with diabetes in China,and the awareness,treatment,and control rates in diabetic patients were:43.3%,49.0%,and 49.4%,***“Sixth National Health Service Statistical Survey Report in 2018”showed that the proportion of the obese population in China was 37.4%,an increase of 7.2 points from *** from 1599 hospitals in the Hospital Quality Monitoring System and Bigdata Observatory Platform for Stroke of China(BOSC)showed that a total of 3,418,432 stroke cases[mean age±standard error(SE)was(65.700±0.006)years,and 59.1%were male]were admitted dur

关键词： Stroke Epidemiological characteristics Treatment Prognosis China