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CSEE Journal of Power and Energy Systems 2024年第1期10卷 162-174页

作者： Yu Zeng Yinliang Xu Xinwei Shen Hongbin Sun tsinghua-Berkeley Shenzhen Institute.tsinghua Shenzhen international Graduate School Tsinghua UniversityShenzhen 518055China department of Electrical Engineering Tsinghua UniversityBeijing 100084China

While price schedules can help improve the economic efficiency of renewable energy-powered microgrids,timeof-use(TOU)pricing has been identified as an effective way for microgrid development,which is presently limited by its high costs.In this study,we propose an evolutionary game theoretic model to explore optimal TOU pricing for development of renewable energy-powered microgrids by applying a multi-agent system,that comprises a government agent,local utility company agent,and different types of consumer agents.In the proposed model,we design objective functions for the company and the consumers and obtain a Nash equilibrium using backward induction.Two pricing strategies,namely,the TOU seasonal pricing and TOU monthly pricing,are evaluated and compared with traditional fixed pricing.The numerical results demonstrate that TOU schedules have significant potential for development of renewable energy-powered microgrids and are recommended for an electric company to replace traditional fixed pricing.Additionally,TOU monthly pricing is more suitable than TOU seasonal pricing for microgrid development.

关键词： Game theory microgrid multi-agent system renewable energy time-of-use pricing

Density-based ship detection in SAR images:Extension to a self-similarity perspective

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Chinese Journal of Aeronautics 2024年第3期37卷 168-180页

作者： Xueqian WANG Gang LI Zhizhuo JIANG Yu LIU You HE department of Electronic Engineering Tsinghua UniversityBeijing 100084China Shenzhen international Graduate School Tsinghua UniversityShenzhen 518055China

Nonlocal self-similarity is an important property of Synthetic Aperture Radar(SAR)images to characterize the repetitiveness of features embodied by SAR images within nonlocal areas and has been used for enhancement of SAR images.Existing SAR ship detectors often independently handle small sub-images cropped from a large marine SAR image and do not exploit the nonlocal self-similarity therein.In this paper,we propose a new ship detector from the perspective of nonlocal self-similarity in SAR images to improve the ship detection performance,basically including three stages:prescreening,intra-cue calculation,and inter-cue calculation.In the prescreening stage,we design a new Histogram-based Density(HD)feature to rapidly select candidate sub-images potentially containing ship targets from a large SAR image.In the intra-cue calculation stage,target cues within a single candidate sub-image are extracted.In the inter-cue calculation stage,thanks to the nonlocal self-similarity among different candidate sub-images in terms of density features,we innovatively extract a weighted superpixel-HD map to obtain accumulated intracues across all the candidate sub-images.Finally,for each candidate sub-image,we fuse its inter-cue and intra-cue to obtain final detection results.Experimental results based on real SAR images show that our newly proposed method provides a better target-to-clutter contrast and ship detection performance than those of other state-of-the-art detection approaches.

关键词： Ship detection Synthetic aperture radar(SAR) Density Self-similarity Histogram

High-resolution portable lens-free on-chip microscopy with RGB LED via pinhole array

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Chinese Optics Letters 2024年第2期22卷 96-100页

作者：王钦骅马建设曹良才苏萍 tsinghua Shenzhen international Graduate School Tsinghua UniversityShenzhen 518055China department of Precision Instrument Tsinghua UniversityBeijing 100084China

Lens-free on-chip microscopy with RGB LEDs(LFOCM-RGB)provides a portable,cost-effective,and high-throughput imaging tool for resource-limited environments.However,the weak coherence of LEDs limits the high-resolution imaging,and the luminous surfaces of the LED chips on the RGB LED do not overlap,making the coherence-enhanced executions tend to undermine the portable and cost-effective implementation.Here,we propose a specially designed pinhole array to enhance coherence in a portable and cost-effective implementation.It modulates the three-color beams from the RGB LED separately so that the three-color beams effectively overlap on the sample plane while reducing the effective light-emitting area for better spatial coherence.The separate modulation of the spatial coherence allows the temporal coherence to be modulated separately by single spectral filters rather than by expensive triple spectral filters.Based on the pinhole array,the LFOCM-RGB simply and effectively realizes the high-resolution imaging in a portable and cost-effective implementation,offering much flexibility for various applications in resource-limited environments.

关键词： lens-free on-chip microscopy LED phase retrieval pinhole array

Lift system optimization for hover-capable flapping wing micro air vehicle

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Frontiers of Mechanical Engineering 2024年第3期19卷 61-75页

作者： Shengjie XIAO Yongqi SHI Zemin WANG Zhe NI Yuhang ZHENG Huichao DENG Xilun DING department of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Shenzhen international Graduate School Tsinghua UniversityShenzhen 518055China

A key challenge is using bionic mechanisms to enhance aerodynamic performance of hover-capable flapping wing micro air vehicle(FWMAV).This paper presented a new lift system with high lift and aerodynamic efficiency,which use a hummingbird as a bionic object.This new lift system is able to effectively utilize the high lift mechanism of hummingbirds,and this study innovatively utilizes elastic energy storage elements and installs them at the wing root to help improve aerodynamic performance.A flapping angle of 154°is achieved through the optimization of the flapping mechanism parameters.An optimized wing shape and parameters are obtained through experimental studies on the wings.Consequently,the max net lift generated is 17.6%of the flapping wing vehicle’s weight.Moreover,energy is stored and released periodically during the flapping cycle,by imitating the musculoskeletal system at the wing roots of hummingbirds,thereby improving the energy utilization rate of the FWMAV and reducing power consumption by 4.5%under the same lift.Moreover,strength verification and modal analyses are conducted on the flapping mechanism,and the weight of the flapping mechanism is reduced through the analysis and testing of different materials.The results show that the lift system can generate a stable lift of 31.98 g with a wingspan of 175 mm,while the lift system weighs only 10.5 g,providing aerodynamic conditions suitable for high maneuverability flight of FWMAVs.

关键词： lift optimization flapping wing elastic energy hovering flapping mechanism

Intensifying electrified flow-through water treatment technologies via local environment modification

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 17-25页

作者： Zheng-Yang Huo Xiaoxiong Wang Xia Huang Menachem Elimelech School of Environment and Natural Resources Institute of Ecological CivilizationRenmin University of ChinaBeijing 100872China Institute for Ocean Engineering Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Center of Double Helix Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China department of Chemical and Environmental Engineering Yale UniversityNew HavenCT 06520-8286USA

Removing high-risk and persistent contaminants from water is challenging,because they typically exist at low concentrations in complex water matrices.Electrified flow-through technologies are viable to overcome the limitations induced by mass transport for efficient contaminant removal.Modifying the local environment of the flow-through electrodes offers opportunities to further improve the reaction kinetics and selectivity for achieving near-complete removal of these contaminants from water.Here,we present state-of-the-art local environment modification approaches that can be incorporated into electrified flow-through technologies to intensify water treatment.We first show methods of nanospace incorporation,local geometry adjustment,and microporous structure optimization that can induce spatial confinement,enhanced local electric field,and microperiodic vortex,respectively,for local environment modification.We then discuss why local environment modification can complement the flow-through electrodes for improving the reaction rate and selectivity.Finally,we outline appropriate scenarios of intensifying electrified flow-through technologies through local environment modification for fit-for-purpose water treatment applications.

关键词： Point-of-use water treatment Electrified membrane Advection-enhanced mass transport Water decontamination and disinfection Emerging contaminants

Mesenteric adipose tissue B lymphocytes promote intestinal injury in severe acute pancreatitis by mediating enteric pyroptosis

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Hepatobiliary & Pancreatic Diseases international 2024年第3期23卷 300-309页

作者： Qing Huang Jia-Wen Liu Hai-Bin Dong Zheng-Jie Wei Jin-Zhe Liu Yu-Tang Ren Xuan Jiang Bo Jiang department of Gastroenterology Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing 102218China

Background:Visceral adipose tissue(VAT)has been linked to the severe acute pancreatitis(SAP)prognosis,although the underlying mechanism remains unclear.It has been reported that pyroptosis worsens SAP.The present study aimed to verify whether mesenteric adipose tissue(MAT,a component of VAT)can cause secondary intestinal injury through the pyroptotic pathway.Methods:Thirty-six male Sprague Dawley(SD)rats were divided into six different groups.Twelve rats were randomly divided into the SAP and control groups.We monitored the changes of MAT and B lymphocytes infiltration in MAT of SAP rats.Twelve SAP rats were injected with MAT B lymphocytes or phosphate buffer solution(PBS).The remaining twelve SAP rats were first injected with MAT B lymphocytes,and then with MCC950(NLRP3 inhibitor)or PBS.We collected blood and tissue samples from pancreas,gut and MAT for analysis.Results:Compared to the control rats,the SAP group showed inflammation in MAT,including higher expression of tumor necrosis factor(TNF-α)and interleukin-6(IL-6),lower expression of IL-10,and histological changes.Flow cytometry analysis revealed B lymphocytes infiltration in MAT but not T lymphocytes and macrophages.The SAP rats also exhibited intestinal injury,characterized by lower expression of zonula occludens-1(ZO-1)and occludin,higher levels of lipopolysaccharide and diamine oxidase,and pathological changes.The expression of NLRP3 and n-GSDMD,which are responsible for pyroptosis,was increased in the intestine of SAP rats.The injection of MAT B lymphocytes into SAP rats exacerbated the inflammation in MAT.The upregulation of pyroptosis reduced tight junction in the intestine,which contributed to the SAP progression,including higher inflammatory indicators and worse histological changes.The administration of MCC950 to SAP+MAT B rats downregulated pyroptosis,which subsequently improved the intestinal barrier and ameliorated inflammatory response of SAP.Conclusions:In SAP,MAT B lymphocytes aggravated local inflammation,and promoted the injury to the int

关键词： Acute pancreatitis Mesenteric adipose tissue B lymphocyte Intestinal barrier Pyroptosis

Control of fine particulate nitrate during severe winter haze in“2+26”cities

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Journal of Environmental Sciences 2024年第2期136卷 261-269页

作者： Chuang Qin Xiao Fu Tao Wang Jian Gao Jiaqi Wang Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China department of Civil and Environmental Engineering Hong Kong Polytechnic UniversityHong Kong 99907China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 10084China

The“2+26”cities,suffering the most severe winter haze pollution,have been the key region for air quality improvement in China.Increasing prominent nitrate pollution is one of the most challenging environmental issues in this region,necessitating development of an effective control strategy.Herein,we use observations,and state-of-the-art model simulations with scenario analysis and process analysis to quantify the effectiveness of the future SO_(2)-NO_(X)-VOC-NH_(3) emission control on nitrate pollution mitigation in“2+26”cities.Focusing on a serious winter haze episode,we find that limited NO_(X)emission reduction alone in the short-term period is a less effective choice than VOC or NH_3emission reduction alone to decrease nitrate concentrations,due to the accelerated NO_(X)-HNO_(3)conversion by atmospheric oxidants and the enhanced HNO_(3)to NO_(3)^(-)partition by ammonia,although deep NO_(X)emission reduction is essential in the long-term period.The synergistic NH_(3) and VOC emission control is strongly recommended,which can counteract the adverse effects of nonlinear photochemistry and aerosol chemical feedback to decrease nitrate more.Such extra benefits will be reduced if the synergistic NH_(3) and VOC reduction is delayed,and thus reducing emission of multiple precursors is urgently required for the effective control of increasingly severe winter nitrate pollution in“2+26”cities.

关键词： Nitrate Winter haze pollution Emission reduction “2+26”cities

Analysis of factors impacting postoperative pain and quality of life in patients with mixed hemorrhoids:A retrospective study

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World Journal of Gastrointestinal Surgery 2024年第3期16卷 731-739页

作者： Xiao-Wen Sun Jing-Yi Xu Chang-Zhen Zhu Si-Jia Li Lu-Jia Jin Zhi-Dong Zhu department of Gastrointestinal Surgery Tsinghua University Affiliated Beijing Tsinghua Changgeng HospitalBeijing 102218China Surgical department Tsinghua University Affiliated Beijing Tsinghua Changgeng HospitalBeijing 102218China

BACKGROUND Hemorrhoids are among the most common and frequently encountered chronic anorectal diseases in anorectal surgery.They are venous clusters formed by con-gestion,expansion,and flexion of the venous plexus in the lower part of the rec-tum.Mixed hemorrhoids bleed easily and recurrently,and this can result in severe anemia.Hence,they may have a negative effect on the health of the patient and surgical treatment is required.Milligan-Morgan hemorrhoidectomy has been widely used since 1937 for the treatment of grade III and IV hemorrhoids.How-ever,most patients experience different degrees of postoperative pain that may cause anxiety.with mixed hemorrhoids post-surgery.METHODS The clinical data of patients with mixed hemorrhoids who underwent Milligan-Morgan hemorrhoidectomy were collected retrospectively.The basic character-istics of the enrolled patients with mixed hemorrhoids were recorded,and based on the Goligher clinical grading system,the hemorrhoids were classified as grades III or IV.The endpoint of this study was the disappearance of pain in all patients.Quantitative data were presented as mean±SD,such as age,pain score,and QoL score.Student’s t-test was used to compare the groups.RESULTS A total of 164 patients were enrolled.The distribution of the visual analog scale pain scores of all patients at 3,7,14 and 28 d after surgery showed that post-surgery pain was significantly reduced with the passage of time.Fourteen days after the operation,the pain had completely disappeared in some patients.Twenty-eight days after the surgery,none of the patients experienced any pain.Comparing the World Health Or-ganization Quality of Life-BREF self-reporting questionnaire scores of patients between 14 and 28 d after surgery,we observed that the quality-of-life scores of the patients post-surgery had significantly improved.There were six items that were compared at 14-and 28-d post-surgery.The mean QoL score 28 d after surgery(4.79±0.46)was higher than that at 14 d post-surgery(3.79±0.57).The mean health condition

关键词： Hemorrhoids Mixed hemorrhoids Milligan organ hemorrhoidectomy Postoperative pain Quality of life Anesthesia mode

Base editor-mediated large-scale screening of functional mutations in bacteria for industrial phenotypes

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Science China(Life Sciences) 2024年第5期67卷 1051-1060页

作者： Yaomeng Yuan Xihao Liao Shuang Li Xin-Hui Xing Chong Zhang MOE Key Laboratory for Industrial Biocatalysis Institute of Biochemical EngineeringDepartment of Chemical EngineeringTsinghua UniversityBeijing 100084China Institute of Biopharmaceutical and Health Engineering Tsinghua Shenzhen International Graduate SchoolShenzhen 518055China Institute of Biomedical Health Technology and Engineering Shenzhen Bay LaboratoryShenzhen 440300China Center for Synthetic and Systems Biology Tsinghua UniversityBeijing 100084China

Base editing,the targeted introduction of point mutations into cellular DNA,holds promise for improving genome-scale functional genome screening to single-nucleotide resolution.Current efforts in prokaryotes,however,remain confined to loss-of-function screens using the premature stop codons-mediated gene inactivation library,which falls far short of fully releasing the potential of base editors.Here,we developed a base editor-mediated functional single nucleotide variant screening pipeline in Escherichia coli.We constructed a library with 31,123 sgRNAs targeting 462 stress response-related genes in E.coli,and screened for adaptive mutations under isobutanol and furfural selective conditions.Guided by the screening results,we successfully identified several known and novel functional mutations.Our pipeline might be expanded to the optimization of other phenotypes or the strain engineering in other microorganisms.

关键词： base editor high-throughput large-scale screening Escherichia coli functional mutation

Elliptical vibration chiseling:a novel process for texturing ultra-high-aspect-ratio microstructures on the metallic surface

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international Journal of Extreme Manufacturing 2024年第2期6卷 449-467页

作者： Zhiwei Li Jianfu Zhang Zhongpeng Zheng Pingfa Feng Dingwen Yu Jianjian Wang State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084People’s Republic of China Beijing Key Laboratory of Precision/Ultra-precision Manufacturing Equipments and Control Department of Mechanical EngineeringTsinghua UniversityBeijing 100084People’s Republic of China Division of Advanced Manufacturing Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055People’s Republic of China

High-aspect-ratio metallic surface microstructures are increasingly demanded in breakthrough applications,such as high-performance heat transfer enhancement and surface plasmon devices.However,the fast and cost-effective fabrication of high-aspect-ratio microstructures on metallic surfaces remains challenging for existing techniques.This study proposes a novel cutting-based process,namely elliptical vibration chiseling(EV-chiseling),for the high-efficiency texturing of surface microstructures with an ultrahigh aspect ratio.Unlike conventional cutting,EV-chiseling superimposes a microscale EV on a backward-moving tool.The tool chisels into the material in each vibration cycle to generate an upright chip with a high aspect ratio through material deformation.Thanks to the tool’s backward movement,the chip is left on the material surface to form a microstructure rather than falling off.Since one microstructure is generated in one vibration cycle,the process can be highly efficient using ultrafast(>1 kHz)tool vibration.A finite element analysis model is established to explore the process mechanics of EV-chiseling.Next,a mechanistic model of the microstructured surface generation is developed to describe the microstructures’aspect ratio dependency on the process parameters.Then,surface texturing tests are performed on copper to verify the efficacy of EV-chiseling.Uniformed micro ribs with a spacing of 1–10μm and an aspect ratio of 2–5 have been successfully textured on copper.Compared with the conventional EV-cutting that uses a forward-moving tool,EV-chiseling can improve the aspect ratio of textured microstructure by up to 40 times.The experimental results also verify the accuracy of the developed surface generation model of microstructures.Finally,the effects of elliptical trajectory,depth of cut,tool shape,and tool edge radius on the surface generation of micro ribs have been discussed.

关键词： metallic microstructure high aspect ratio backward-moving cutting vibration cutting chiseling material deformation