Distributed Robust UAVs Formation Control Based on Semidefinite Programming

The formation control of unmanned aerial vehicle(UAV)swarms is of significant importance in various fields such as transportation,emergency management,and environmental monitoring.However,the complex dynamics,nonlinearity,uncertainty,and interaction among agents make it a challenging problem.In this paper,we propose a distributed robust control strategy that uses only local information of UAVs to improve the stability and robustness of the formation system in uncertain environments.We establish a nominal control strategy based on position relations and a semi-definite programming model to obtain control gains.Additionally,we propose a robust control strategy under the rotation setΩto address the noise and disturbance in the system,ensuring that even when the rotation angles of the UAVs change,they still form a stable formation.Finally,we extend the proposed strategy to a quadrotor UAV system with high-order kinematic models and conduct simulation experiments to validate its effectiveness in resisting uncertain disturbances and achieving formation control.

Quantitative and Comprehensive Prediction of Shale Oil Sweet Spots in Qingshankou Formation, Songliao Basin

The mud shale of Qingshankou Formation in Songliao Basin is the main rock source and contains rich shale oil resources. The successful development of shale oil depends on evaluating and optimizing the “sweet spots”. To accurately identify and optimize the favorable sweet spots of shale oil in Qingshankou Formation, Songliao Basin, the original logging data were preprocessed in this paper. Then the thin mud shale interlayer of Qingshankou Formation was identified effectively by using the processed logging data. Based on the artificial neural network method, the mineral content of mud shale in Qingshankou Formation was predicted. The lithofacies were identified according to the mineral and TOC content. Finally, a three-dimensional (3-D) model of total organic carbon (TOC), vitrinite reflectance (Ro), mineral content, and rock of Qingshankou Formation in Songliao Basin was established to evaluate and predict the favorable sweet spots of shale oil in the study area. The results show that there are a lot of calcareous and siliceous thin interlayers in Qingshankou Formation, and TOC content is generally between 2% and 3%. Ro is the highest in Gulong sag, followed by Sanzhao sag. The lithofacies mainly consists of felsic shale and mixed shale, mainly in the first member of Qingshankou Formation. Comprehensive analysis shows that shale oil development potential is enormous in the eastern part of Sanzhao Sag and the northern part of Gulong Sag.

Investigation into Spatter Particles and Their Effect on the Formation Quality During Selective Laser Melting Processes

During the selective laser melting process,a high-energy laser beam acts on the powder,a molten pool is rapidly generated and the characteristic parameters are constantly changing.Among them,temperature is one of the important parameters in the forming process.Due to the generation of splash particles,there will be defects in the microstructure,which will seriously affect the formation quality of the prepared parts.Therefore,it is necessary to study the relationships between the splash behavior,molten pool characteristics and product quality.The finite element simulation of the transient temperature field was performed by ANSYS software.Time-series images at different frame rates were obtained with a high-speed camera,and the dynamic process of splashing was observed.Using IN718 alloy powder,the influence of the laser energy density on the light intensity of the molten pool was studied.The appearance of splash particles and the deviation of the powder chemical elements caused by the splash were analyzed.The results show that the transient temperature field with drastic change is easy to cause spatter,which is consistent with the experimental results.There are large differences in the splash at different shooting frame rates.Increasing the frame rate can allow the observation of details such as the shape,size and number of splash particles,which is beneficial for studying the process of splash formation.At the moment when the splash occurs,the light intensity of the molten pool always first increases and then decreases,depending on the energy input.The higher the energy input is,the more intense the light intensity of the molten pool and the higher the peak interval distribution.Compared with fresh powder,the contents of Al and Ti in powder reused 5 times were reduced by 0.15%and 0.02%,respectively.The increases of these two elements in the splash were 16.18%and 29.62%,respectively,and the content of Nb even exceeded the standard range.When the energy density decreased from 229.17 J/mm3 to 130.95 J/mm3,the relative density of the part increased from 91.82%to 99.83%.This shows that reducing the energy input can reduce the splash to suppress the generation of defects,along with the weakening of the overall light intensity of the molten pool.These results can provide a basis for feature extraction of the molten pool,which is of great significance for real-time monitoring and online control in manufacturing processes and ensuring product quality.

Innovative Design and Additive Manufacturing of Regenerative Cooling Thermal Protection System Based on the Triply Periodic Minimal Surface Porous Structure

The new regenerative cooling thermal protection system exhibits the multifunctional characteristics of load-carrying and heat exchange cooling,which are fundamental for the lightweight design and thermal protection of hypersonic vehicles.Triply periodic minimal surface(TPMS)is especially suitable for the structural design of the internal cavity of regenerative cooling structures owing to its excellent structural characteristics.In this study,test pieces were manufactured using Ti6Al4V lightweight material.We designed three types of porous test pieces,and the interior was filled with a TPMS lattice(Gyroid,Primitive,I-WP)with a porosity of 30%.All porous test pieces were manufactured via selective laser melting technology.A combination of experiments and finite element simulations were performed to study the selection of the internal cavity structure of the regenerative cooling thermal protection system.Hence,the relationship between the geometry and mechanical properties of a unit cell is established,and the deformation mechanism of the porous unit cell is clarified.Among the three types of porous test pieces,the weight of the test piece filled with the Gyroid unit cell was reduced by 8.21%,the average tensile strength was reduced by 17.7%compared to the solid test piece,while the average tensile strength of the Primitive and I-WP porous test pieces were decreased by 30.5%and 33.3%,respectively.Compared with the other two types of unit cells,Gyroid exhibited better mechanical conductivity characteristics.Its deformation process was characterised by stretching,shearing,and twisting,while the Primitive and I-WP unit cells underwent tensile deformation and tensile and shear deformation,respectively.The finite element predictions in the study agree well with the experimental results.The results can provide a basis for the design of regenerative cooling thermal protection system.

Integrative metabolomics and transcriptomics analyses reveal pivotal regulatory mechanisms of 1-methylcyclopropene in maintaining postharvest storage quality of‘Fuji’apples

In this study,integrative metabolomics and transcriptomics analyses were conducted to investigate the effects of 1-methylcyclopropene(1-MCP)on apple fruit quality during long-term cold storage.The results showed that 1-MCP(1μL/L)treatment could maintain fruits apparent quality(i.e.external color and firmness),inhibit the increase of rot rate and soluble solids content/titratable acidity ratio,decrease ethylene release,and respiratory intensity during cold storage,and extend shelf life.Moreover,1-MCP had long-term effects on the accumulation of many qualities related to metabolite and gene expression in fruits.1-MCP affected genes related to metabolism at the early stage of storage,specifically those of the glycolysis and tricarboxylic acid cycle pathways.Genes related to the degradation of sucrose,starch,and cellulose were inhibited,and some starch and cellulose synthesis genes were up-regulated by 1-MCP.Apart from ethylene synthesis and signal transduction being inhibited by 1-MCP,several enzymes(pectinesterase,pectate lyase,polygalacturonase)were involved in pectin degradation,and degradation products of the cell wall(i.e.D-galacturonic acid and D-glucuronic acid)were also strongly inhibited,further maintaining fruit firmness.Cysteine,as precursor glutathione(GSH)related to plant resistance,up-regulated the synthase gene.However,the expression of genes related to cyanoalanine syn-thase and amino acid utilization pathways was suppressed by 1-MCP Collectively,1-MCP could maintain the postharvest quality of apple fruits.

Interactive effects of warming and eutrophication on zooplankton could reverse the stoichiometric mismatch with phytoplankton

The core ecosystem functioning(e.g.trophic transfer efficiency)is at risk of being disrupted by the growing mismatch between nutrient content of primary producers and nutrient demand of grazing consumers.Ecological stoichiometry provides a conceptual framework that explains this trophic interaction using C,N and P elemental composition across trophic levels.In light of ongoing climate change and eutrophication,previous studies have raised concerns regarding the growing stoichiometric mismatch between phytoplankton and zooplankton,given the stoichiometric plasticity of phytoplankton.However,there is currently little conclusive evidence on the stoichiometric mismatch from a dual perspective of phytoplankton and zooplankton.To address this,we conducted a mesocosm experiment to investigate the separate and combined effects of climate warming(a constant increase of t3.5C plus heat waves)and eutrophication(nutrient addition)on stoichiometric mismatch between phytoplankton and zooplankton by examining stoichiometric changes in both communities.We observed a growing trend in stoichiometric mismatches when warming or nutrient addition acted individually,which was mediated by the increase in nutrient demand(N,P elements)of zooplankton growth.However,when these stressors acted jointly,the mismatches were reversed.This could be because climate warming and eutrophication combined would lead to changes in species composition,which accordingly reshaped the stoichiometric composition at the community level.These results illustrate the need of stoichiometric mismatches for understanding the implication of global change on trophic interactions and ecosystem functioning,requiring consideration not only of cross-trophic levels but also of compositional changes within communities.

丙酮丁醇梭菌半胱氨酸合成途径中铁氧还蛋白和胱硫醚-γ-裂解酶基因功能

【目的】探究丙酮丁醇梭菌半胱氨酸合成代谢途径上铁氧还蛋白和胱硫醚-γ-裂解酶基因的功能。【方法】使用ClosTron系统对半胱氨酸合成途径上的铁氧还蛋白基因(fer)和胱硫醚-γ-裂解酶基因(mccB)进行失活,得到突变株;在不同硫源的培养基中进行分批发酵,分析突变株的生长特点;通过pH控制,使用限磷的连续发酵方法将丙酮丁醇梭菌维持在产酸期和产溶剂期,分析野生型菌株和突变株在连续发酵中的生长情况。【结果】成功构建Δfer和ΔmccB突变株。在分批发酵中,敲除fer基因的突变株无法利用硫酸盐作为硫源,但添加亚硫酸盐或半胱氨酸可以使其恢复生长;在以半胱氨酸为唯一硫源进行分批发酵时,其终浓度1 mmol/L时不会影响野生型与Δfer突变株的生长,但高于1 mmol/L时生长均会受到抑制。在连续发酵中,Δfer突变株不能在产溶剂阶段生长,添加过量的半胱氨酸也不能恢复生长;敲除mccB基因的突变株仍能在添加甲硫氨酸的培养基中生长,但最大OD仅为野生型的57%;相较于野生型,ΔmccB突变株在产酸期和产溶剂期的生长均受到抑制。【结论】fer基因为半胱氨酸合成途径中硫酸盐还原为亚硫酸盐的关键基因,其控制合成的半胱氨酸不能完全由外源的半胱氨酸替代,敲除后对生长的抑制主要表现在连续发酵中的产溶剂阶段。mccB基因参与调控甲硫氨酸转化为半胱氨酸的过程,其敲除会影响甲硫氨酸到半胱氨酸的转化,但不会阻断该生物反应过程。

嗜热厌氧菌Caldicellulosiruptor sp. F32中降解β-1,3-1,4葡聚糖水解酶的协同性分析及糖基化对F32EG5热稳定性影响

【目的】通过研究来自极端嗜热厌氧菌Caldicellulosiruptor sp.F32中3个可降解β-1,3-1,4葡聚糖(β-葡聚糖)的糖苷水解酶,解析其在降解β-葡聚糖过程中协同作用,以及异源表达的糖基化修饰对β-葡聚糖酶F32EG5热稳定性的影响,为该系列水解酶的应用提供考据。【方法】通过大肠杆菌异源表达β-葡聚糖酶F32EG5和Lam16A-GH,以及β-葡萄糖苷酶BlgA,利用DNS、TLC等方法检测其在β-葡聚糖降解过程中的协同性及底物耐受能力。随后,利用毕赤酵母对F32EG5进行异源表达,以及对糖基化修饰的p-F32EG5进行酶学对比。【结果】β-葡聚糖酶F32EG5和Lam16A-GH单独作用于底物时,水解产物不同。但混合使用时,低聚合度寡糖的比例增加。β-葡萄糖苷酶BlgA分别与F32EG5和Lam16A-GH复配时,均展示出良好的协同效应和底物耐受能力。此外,利用毕赤酵母异源表达的p-F32EG5,没有明显改变其最适pH和最适温度,但在超高温下(80–90°C)的热稳定性和催化效率相对于未被糖基化的F32EG5提高2倍以上。【结论】葡萄糖糖苷水解酶BlgA分别与β-葡聚糖酶F32EG5、Lam16A-GH复配,在水解β-葡聚糖过程中表现出良好的协同性和底物耐受能力,同时毕赤酵母异源表达的糖基化修饰能提高在超高温环境下的热稳定性能,有利于酶制剂生产造粒过程中的酶活保留,从而使F32EG5具备应用化潜力。

Heterogeneously integrated,superconducting silicon-photonic platform for measurementdevice-independent quantum key distribution

Integrated photonics provides a route to both miniaturization of quantum key distribution(QKD)devices and enhancing their performance.A key element for achieving discrete-variable QKD is a singlephoton detector.It is highly desirable to integrate detectors onto a photonic chip to enable the realization of practical and scalable quantum networks.We realize a heterogeneously integrated,superconducting silicon-photonic chip.Harnessing the unique high-speed feature of our optical waveguide-integrated superconducting detector,we perform the first optimal Bell-state measurement(BSM)of time-bin encoded qubits generated from two independent lasers.The optimal BSM enables an increased key rate of measurement-device-independent QKD(MDI-QKD),which is immune to all attacks against the detection system and hence provides the basis for a QKD network with untrusted relays.Together with the timemultiplexed technique,we have enhanced the sifted key rate by almost one order of magnitude.With a 125-MHz clock rate,we obtain a secure key rate of 6.166 kbps over 24.0 dB loss,which is comparable to the state-of-the-art MDI-QKD experimental results with a GHz clock rate.Combined with integrated QKD transmitters,a scalable,chip-based,and cost-effective QKD network should become realizable in the near future.

Reinforcement of the two-stage leaching of laterite ores using surfactants

A two-stage leaching process,namely,highpressure acid leaching-atmospheric acid leaching,was used to treat laterite ores under mild conditions.The leaching ratio of Ni was low because of adsorption and incomplete leaching.In this work,surfactants were used as additives to boost the leaching ratio of Ni.The effect of surfactant type(cationic,anionic,and nonionic surfactants)on the leaching ratio of Ni was investigated.Leaching results showed that stearyl trimethyl ammonium chloride(STAC)apparently increased the leaching ratios of valuable metals.The variation in the physicochemical properties of the lixiviant and the residue improved the leaching ratio of Ni in the presence of STAC.Kinetics analysis indicated that the leaching process was controlled by chemical reaction.

High-quality quantum process tomography of time-bin qubit’s transmission over a metropolitan fiber network and its application

We employ quantum state and process tomography with time-bin qubits to benchmark a city-wide metropolitan quantum communication system.Over this network,we implement real-time feedback control systems for stabilizing the phase of the time-bin qubits and obtain a 99.3%quantum process fidelity to the ideal channel,indicating the high quality of the whole quantum communication system.This allows us to implement a field trial of high-performance quantum key distribution using coherent one way protocol with an average quantum bit error rate and visibility of 0.25%and 99.2%during 12 h over 61 km.Our results pave the way for the high-performance quantum network with metropolitan fibers.

Effects of nitric oxide treatment on flavour compounds and antioxidant enzyme activities of button mushroom (Agaricus bisporus) during storage

Button mushroom(Agaricus bisporus)is sold well for its unique flavour and nutritional benefits.However,the mushroom flavour deteriorates quickly during storage because of its delicate structure and high moisture.In this study,the effects of nitric oxide(NO)application on flavour compounds and antioxidant enzyme activities of stored button mushrooms were investigated.The button mushrooms were immersed in the NO donor sodium nitroprusside(15μmol/L)for 3 min and then stored under the condition of 4℃,90%relative humidity for 12 days.Results showed that the treated mushrooms have reduced weight loss rate,uniform white colour,and higher firmness during storage.Compared to the control,the ketones,alcohols,esters,and aldehydes in the NO-treated button mushroom increased sharply at 3 days of storage and then showed a continuing decline trend,except ester compounds which reached the peak value at 6 days of storage.In addition,NO treatment increased the total phenolics and catalase activity and inhibited the polyphenol oxidase activity in the stored button mushroom.These results indicated that NO treatment is an alternative storage technology to enhance antioxidant capacity and maintain flavour and consumer acceptance of stored button mushroom.

Boosting photocatalytic activity through tuning electron spin states and external magnetic fields

Photocatalysis is considered as one of the most promising technologies to generate renewable energy and degrade environmental pollutants.Tremendous efforts have been made to improve photocatalytic efficiency.Among these,tuning spin polarization and introducing an external magnetic field are considered two promising strategies to boost photocatalytic performance.Herein this review highlights the recent breakthroughs through manipulating spin states and applying external magnetic fields for enhancing photocatalytic reactions.The relevant characterization techniques and fundamental mechanisms are summarized.Spin polarization states of photocatalysts have received considerable attention due to their unique roles,including inhibiting the recombination of photoexcited carriers owing to spin orientation constraint,enhancing the reaction product selectivity,and reducing the reaction barriers via optimizing the absorption energy and binding strength.As for the effects of external magnetic field on photocatalytic performance,we mainly discuss the separation enhancement of photoinduced carriers under static and time-varying magnetic fields and the magneto-hydrodynamic effect of charged particles.Lastly,the negative magnetoresistance effect is discussed due to the synergistic effects of the electron spin state and an external magnetic field.These discussions in this review may provide new insights into designing new semiconductors for boosting photocatalytic performance in internal and external magnetic fields.

lncRNAX-inactive-specific transcript is a potential biomarker related to changes in CD4+T cell levels in systemic lupus erythematosus

Background:Systemic lupus erythematosus(SLE)is a particularly heterogeneous autoimmune disease.This study was intended to clarify the correlations between X-inactive-specific transcript(XIST)expression and SLE clinical features and the contribution of XIST to SLE pathogenesis at the transcriptome level.Methods:XIST expression in 79 SLE patients,14 rheumatoid arthritis patients,and 23 healthy controls was determined by quantitative polymerase chain reaction.The Benjamini and Hochberg adjusted method and multivariate linear regression were applied to correct p-values and adjust confounding factors,respectively.Bioinformatic methods were used to explore the function and regulatory mechanism of XIST.Results:XIST was significantly elevated in peripheral blood mononuclear cells and CD4^(+)T cells from SLE patients compared with the levels in healthy controls and had potential diagnostic value for SLE.Notably,XIST expression was positively correlated with the SLE disease activity index and significantly reduced after effective treatment.Moreover,SLE patients with high XIST expression tended to have elevated levels of CD4^(+)T cells,but reduced levels of NK cells.Bioinformatic analyses suggested that XIST may regulate OLFM4 and CEACAM8 expression by acting as a spongy body for miR-20a,miR-92a,miR-106a,and miR-449a.Furthermore,CEACAM8 was significantly upregulated in CD4^(+)T cells from SLE patients and significantly positively correlated with XIST expression.Conclusions:lncRNA XIST,a potential diagnostic and therapeutic biomarker for SLE,is involved in the change of immune cell balance in the peripheral blood of SLE patients.Mechanistically,XIST may regulate the miR-17-92-CEACAM8 axis to achieve this in CD4^(+)T cells.

Co-delivery of enzymes and photosensitizers via metal-phenolic network capsules for enhanced photodynamic therapy

The intrinsic hypoxic tumor microenvironment and limited accumulation of photosensitizers(PSs) result in unsatisfied efficiency of photodynamic therapy(PDT).To enhance the PDT efficiency against solid tumors,a functional oxygen self-supplying and PS-delivering nanosystem is fabricated via the combination of catalase(CAT),chlorin e6(Ce6) and metal-phenolic network(MPN) capsule.It is demonstrated that the CAT encapsulated in the capsules(named CCM capsules) could catalyze the degradation of hydrogen peroxide(H;O;) to produce molecular oxygen(O;),which could be converted into cytotoxicity reactive oxygen species(ROS) by surface-loaded Ce6 under 660 nm laser irradiation,leading to synergistic anticancer effects in vitro and in vivo.Therefore,the application of CCM capsule could be a promising strategy to improve PDT effectiveness.

Freshwater snail and shrimp differentially affect water turbidity and benthic primary producers

Benthic macroinvertebrates play key roles in shallow aquatic ecosystems and can contribute substantially to aquatic food webs.However,how macroinvertebrates with different behaviors(for example,pertaining to locomotion,foraging and burrowing)impact water quality and primary producers has not been fully explored.Here,we performed two consecutive microcosm experiments to test the effects of(1)macroinvertebrates with different behaviors(a low mobility scraper aquatic snail Bellamya aeruginosa and a high mobility shredder freshwater shrimp Macrobrachium nipponense)and(2)different shrimp biomasses on water clarity and the composition of benthic primary producers.The results showed that presence of snails significantly increased the biomass of filamentous green algae and decreased the biomass of periphyton.In contrast,presence of shrimp significantly decreased the biomass of filamentous green algae and increased the biomass of periphyton,and these effects were biomass dependent.Filamentous green algae disappeared when shrimp biomass reached 9.8 g m^(-2).No interactive effects of snail and shrimp presence were found.This could be attributed to different food preferences by the two consumers,with snails preferring periphyton(mainly diatoms)and shrimp preferring filamentous green algae.The presence of snails decreased water turbidity,while shrimp increased water turbidity,which showed a hump-shaped response to shrimp biomass with a peak at 24.2 g m^(-2).These results are likely because the snail is a low mobility grazer and can filter suspended particles,while the shrimp is a high mobility shredder with burrows,which can strongly disturb sediment.The decrease in water disturbance at high shrimp biomass might be due to food limitation,thus reducing burrowing and foraging activities.Neither snail nor shrimp affected the biomass of H.verticillata,while the biomass of V.spinulosa increased with shrimp biomass.The reason for this could be that shrimp increased nutrient availability and decreased the growth of filamentous green algae that compete with macrophytes.Our study demonstrated that different macroinvertebrates have complementary functions in benthic habitats;thus,maintaining macroinvertebrate diversity is important for shallow aquatic ecosystems.Furthermore,the freshwater shrimp M.nipponense could be a potential consumer to control filamentous green algal blooms in its native range,but their biomass should be taken into consideration.