协同光电及热效应实现铜光阴极上等离激元催化高效硝酸根还原反应

近年来,电催化硝酸根还原反应(NO_(3)RR)已经成为水处理和合成氨领域的研究热点.相比于传统的电催化剂,等离激元辅助的电催化反应通过将太阳能和电化学偏压同时施加到金属纳米结构上,在实现高效太阳能到化学能转化领域展现出了巨大潜力.然而,目前有关等离激元辅助NO_(3)RR的文献报道较少,已有的研究主要集中于利用金(Au)纳米结构的等离激元效应辅助增强NO_(3)RR.但Au对NO_(3)RR的本征电催化活性很差,这导致在等离激元辅助NO_(3)RR领域,氨的产率和法拉第效率难以令人满意.此外,对于等离激元辅助NO_(3)RR的机理研究不深入,例如如何区分等离激元产生的光电效应和光热效应对NO_(3)RR的影响,以及等离激元激发的金属纳米结构是如何影响NO_(3)RR过程等问题都尚未解决.因此,有必要采取有效的策略来深入探究等离激元辅助NO_(3)RR的内在机制,从而进一步提高其催化性能.铜(Cu)作为一种高效的硝酸根还原电催化剂,同时是一种典型的具有等离激元效应的金属材料.然而,目前关于利用Cu的等离激元效应辅助增强NO_(3)RR的报道很少.本文报道了利用Cu纳米线(CuNWs)的等离激元效应辅助增强NO_(3)RR性能.在等离激元激发条件下,CuNWs展现出较好的NO_(3)RR催化性能.在协同的光电和热效应的作用下,与暗态常温条件相比,催化性能提升了近2倍.经过400次循环伏安测试,CuNWs光阴极的电流密度仅下降到初始值的88%,而在黑暗条件下,CuNWs光阴极催化NO_(3)RR的电流密度则下降了43%.这表明光照同时显著提升了CuNWs催化NO_(3)RR的稳定性.产物分析结果表明,在-0.2到-0.4 V(相对于可逆氢电极)的宽电势范围内,CuNWs光阴极实现了接近100%的氨法拉第效率,并取得了较高的氨产率,超过了之前大多数报道的等离激元辅助Au催化剂的NO_(3)RR性能.通过活化能实验、微分电流实验以及升温实验,区分了等离激元激发产生的光电效应以及光热效应对NO_(3)RR的影响.通过原位拉曼光谱、在线差分电化学质谱以及原位电化学红外光谱技术,确定了CuNWs光阴极NO_(3)RR过程中的活性相及反应中间体.密度泛函理论计算结果表明,氨的脱附是NO_(3)RR的决速步.光生电子可以通过电子跃迁激发脱附机制促进氨的脱附从而抑制了氨在Cu表面的累积,弱化了氨对CuNWs光阴极的毒化作用.同时,光热效应也显著提升了NO_(3)RR的反应速率.因此,等离激元激发产生的光电和光热效应协同促进了NO_(3)RR性能,提高了CuNWs光阴极的活性与稳定性.将该策略拓展到其它Cu纳米材料上,同样展现出较好的等离激元促进效果.综上,本文提出了利用Cu的等离激元效应辅助增强电催化NO_(3)RR性能的策略,并验证了该策略在其它Cu纳米材料上的适用性.深入的机理研究揭示了同时耦合太阳能、电能以及热能对进一步提升NO_(3)RR性能的巨大潜力.

Heteroatoms doped iron oxide-based catalyst prepared from zinc slag for efficient selective catalytic reduction of NO_(x) with NH_(3)

Excessive emissions of nitrogen oxides from flue gas have imposed various detrimental impacts on environment,and the development of deNO_(x) catalysts with low-cost and high performance is an urgent requirement.Iron oxide-based material has been explored for promising deNO_(x) catalysts.However,the unsatisfactory low-temperature activity limits their practical applications.In this study,a series of excellent low-temperature denitrification catalysts(Ha-FeO_(x)/yZS)were prepared by acid treatment of zinc slag,and the mass ratios of Fe to impure ions was regulated by adjusting the acid concentrations.Ha-FeO_(x)/yZS showed high denitrification performance(>90%)in the range of 180–300℃,and the optimal NO conversion and N2 selectivity were higher than 95%at 250℃.Among them,the Ha-FeO_(x)/2ZS synthesized with 2 mol/L HNO3 exhibited the widest temperature window(175–350℃).The excellent denitrification performance of Ha-FeO_(x)/yZS was mainly attributed to the strong interaction between Fe and impurity ions to inhibit the growth of crystals,making Ha-FeO_(x)/yZS with amorphous structure,nice fine particles,large specific surface area,more surface acid sites and high chemisorbed oxygen.The in-situ DRIFT experiments confirmed that the SCR reaction on the Ha-FeO_(x)/yZS followed both Langmuir-Hinshelwood(L-H)mechanism and Eley-Rideal(E-R)mechanism.The present work proposed a high value-added method for the preparation of cost-effective catalysts from zinc slag,which showed a promising application prospect in NO_(x) removal by selective catalytic reduction with ammonia.

Sodium butyrate alleviates fructose-induced non-alcoholic fatty liver disease by remodeling gut microbiota to promoteγ-amino butyric acid production

Sodium butyrate(NaB)can regulate lipid metabolism and inhibit hepatic steatosis.This study aimed to investigate whether NaB can alleviate fructose-induced hepat ic steatosis via remodeling the gut microbiota and evaluate the anti-fatty liver mechanisms.The results showed that NaB and NaB-remodeled gut microbiota significantly alleviated fructose-induced hepatic steatosis and increased plasma uric acid and fructose levels.Furthermore,both NaB and NaB-remodeled gut microbiota increased the abundance of Lactobacillus and altered the levels of plasma amino acids(upregulating gamma-amino butyric acid(GABA)and downregulating L-glutamic acid and L-arginine)in fructose-exposed mice.The correlation analysis showed that GABA levels positively correlated with Lactobacillus abundance,and increased GABA levels might promote the reduction of the hepatic triglyceride content.Further studies confirmed that GABA significantly reduced lipid deposition in mouse hepatocytes induced via fructose pretreatment in vitro.These findings suggested that NaB could ameliorate fructose-induced hepatic steatosis by regulating gut microbiota.

Efficacy of hepatic arterial infusion chemotherapy and its combination strategies for advanced hepatocellular carcinoma:A network meta-analysis

BACKGROUND With the rapid progress of systematic therapy for hepatocellular carcinoma(HCC),therapeutic strategies combining hepatic arterial infusion chemotherapy(HAIC)with systematic therapy arised increasing concentrations.However,there have been no systematic review comparing HAIC and its combination strategies in the first-line treatment for advanced HCC.AIM To investigate the efficacy and safety of HAIC and its combination therapies for advanced HCC.METHODS A network meta-analysis was performed by including 9 randomized controlled trails and 35 cohort studies to carry out our study.The outcomes of interest comprised overall survival(OS),progression-free survival(PFS),tumor response and adverse events.Hazard ratios(HR)and odds ratios(OR)with a 95% confidence interval(CI)were calculated and agents were ranked based on their ranking probability.RESULTS HAIC outperformed Sorafenib(HR=0.55,95%CI:0.42-0.72;HR=0.51,95%CI:0.33-0.78;OR=2.86,95%CI:1.37-5.98;OR=5.45,95%CI:3.57-8.30;OR=7.15,95%CI:4.06-12.58;OR=2.89,95%CI:1.99-4.19;OR=0.48,95%CI:0.25-0.92,respectively)and transarterial chemoembolization(TACE)(HR=0.50,95%CI:0.33-0.75;HR=0.62,95%CI:0.39-0.98;OR=3.08,95%CI:1.36-6.98;OR=2.07,95%CI:1.54-2.80;OR=3.16,95%CI:1.71-5.85;OR=2.67,95%CI:1.59-4.50;OR=0.16,95%CI:0.05-0.54,respectively)in terms of efficacy and safety.HAIC+lenvatinib+ablation,HAIC+ablation,HAIC+anti-programmed cell death 1(PD-1),and HAIC+radiotherapy had the higher likelihood of providing better OS and PFS outcomes compared to HAIC alone.HAIC+TACE+S-1,HAIC+lenvatinib,HAIC+PD-1,HAIC+TACE,and HAIC+sorafenib had the higher likelihood of providing better partial response and objective response rate outcomes compared to HAIC.HAIC+PD-1,HAIC+TACE+S-1 and HAIC+TACE had the higher likelihood of providing better complete response and disease control rate outcomes compared to HAIC alone.CONCLUSION HAIC proved more effective and safer than sorafenib and TACE.Furthermore,combined with other interventions,HAIC showed improved efficacy over HAIC monotherapy according to the treatment ranking analysis.

Rheo-NMR: A versatile hyphenated technique for capturing molecular dynamics and structure under flow

The general development of Rheo-NMR during the last four decades as well as selective hyphenated apparatuses is presented.Based on different magnet types,the current review is divided into two categories,namely low-field and high-field NMR,while the timedomain NMR is normally applied in the former case and the frequency-domain NMR is adopted in the latter one.Depending on different rheometer cells,it can be further divided into tensile and shear mode Rheo-NMR.The combination of various rheometer cells and NMR facility guarantees our acquisition of molecular level structure and dynamics information under flow conditions,which is crucial for our understanding of the molecular origin of complex fluids.A personal perspective is also presented at last to highlight possible development in this direction.

改进EEMD算法在高压并联电抗器声信号去噪中的应用

高压并联电抗器运行过程中产生的声信号是准确判定电抗器运行状态的重要依据,在对电抗器声信号现场采集时易受到多种外界噪声的干扰,测量仪器无法有效进行预处理,导致对电抗器运行状态的评估发生误判。提出了一种基于多传感器融合及最小下限频率截止的改进集合经验模态分解(ensemble empirical mode decomposition,EEMD)高压并联电抗器声信号去噪方法。首先,利用一致性数据融合算法对各声纹传感器进行关联和甄别,剔除失效传感器,确定有效传感器组。其次,选取有效传感器组中的最小下限频率作为固有模态函数(intrinsicmode function, IMF)的筛选截止条件并进行集合经验模态分解。然后利用相关系数法提取有效的IMF分量。最后对有效IMF分量叠加重构,得到去噪声信号。模拟实验和实测结果表明,该方法具有较好的去噪效果。通过与传统经验模态分解法(empirical mode decomposition, EMD)、标准EEMD去噪技术的比较,验证了该方法在实际应用过程中的有效性和实用性。

Artificial neural network-based one-equation model for simulation of laminar-turbulent transitional flow

A mapping function between the Reynolds-averaged Navier-Stokes mean flow variables and transition intermittency factor is constructed by fully connected artificial neural network(ANN),which replaces the governing equation of the intermittency factor in transition-predictive Spalart-Allmaras(SA)-γmodel.By taking SA-γmodel as the benchmark,the present ANN model is trained at two airfoils with various angles of attack,Mach numbers and Reynolds numbers,and tested with unseen airfoils in different flow states.The a posteriori tests manifest that the mean pressure coefficient,skin friction coefficient,size of laminar separation bubble,mean streamwise velocity,Reynolds shear stress and lift/drag/moment coefficient from the present two-way coupling ANN model almost coincide with those from the benchmark SA-γmodel.Furthermore,the ANN model proves to exhibit a higher calculation efficiency and better convergence quality than traditional SA-γmodel.

Deep Reinforcement Learning for IRS-Assisted UAV Covert Communications

Covert communications can hide the existence of a transmission from the transmitter to receiver.This paper considers an intelligent reflecting surface(IRS)assisted unmanned aerial vehicle(UAV)covert communication system.It was inspired by the high-dimensional data processing and decisionmaking capabilities of the deep reinforcement learning(DRL)algorithm.In order to improve the covert communication performance,an UAV 3D trajectory and IRS phase optimization algorithm based on double deep Q network(TAP-DDQN)is proposed.The simulations show that TAP-DDQN can significantly improve the covert performance of the IRS-assisted UAV covert communication system,compared with benchmark solutions.

外界热辐射条件下油品燃烧特性模拟实验研究

针对油品在外界热辐射条件下的释热及燃烧速率特性表现研究需要,搭建了小尺度油品燃烧特性实验台架,研究了0#柴油和航空煤油在不同外界辐射强度下的释热速率和燃烧速率特性,拟合出了释热及燃烧速率关于外界辐射强度的关系式,结合有效燃烧热特性参数,比较了两种油品在相同外界辐射条件下燃烧效率的差异,为油料储运工程实际油品安全管控提供了有效建议。

Distribution and conservation of near threatened plants in China

Plants classified as Near Threatened(NT) are at high risk of becoming threatened because of anthropogenic interference and climate change.Especially in conservation efforts,such species have however long been overlooked.Here,we obtained 98,419 precise occurrence points for 2442 NT plants in China,and used species richness,species complementarity,and weighted endemism that consider all,endemic and narrow-ranged species in order to identify the diversity hotspots of NT plants.Then we evaluated the conservation effectiveness of current nature reserves for them.Our results indicate that the diversity hotspots of NT plants were mainly confined to southwestern and southern China,and only 35.87% of hotspots and 71.5% of species were protected by nature reserves.Numerous hotspots in southwestern China(e.g.,Sichuan,Yunnan,Guangxi,and Hainan) were identified as conservation gaps.Given that NT plants include large proportions of endemic and narrow-ranged species,they represent an important value in conservation priority.So,more conservation efforts in the future should be tilted towards NT plants.Additionally,when comparing with the recently updated NT list,there are already 87 species raised to threatened categories,while 328 species were lowered to least concern,56 species were now categorized as data deficient,and 119 species considered as uncertain due to changes of scientific names.It is essential to carry out a continuous assessment of species’ threatened categories to realize targeting conservation.

Restraining migration and dissolution of transition-metal-ions via functionalized separator for Li-rich Mn-based cathode with high-energy-density

Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and capacity fade due to continual migration and dissolution of transition metal ions(TMs) during cycling process.Herein,a novel strategy is proposed to inhibit the TMs migration of LRMs through a modified separator by means of functionalized carbon coating layer,which depends on the chemical constraint of the abundant functional groups in the modified super P.In addition,it has been found that the dissolution of TMs can be restrained based on the Le Chatelier's principle.Moreover,the modified separator owns good wettability toward the electrolyte.As a result,the LRMs cathode with the modified separator delivers a high discharge capacity of 329.93 mA h g-1 at 0.1 C,and achieves good cyclic performance,the enhanced reaction kinetics and low voltage decay.Therefore,this work provides a new idea to promote the comprehensive electrochemical performances of Li-ion batteries with LRMs cathode through a strategy of separator modification.

Magic wavelengths for 6s_(1/2)→5d_(3/2,5/2)transitions of Yb~+ions

The wave functions,energy levels and matrix elements of Yb+ions are calculated using the relativistic configuration interaction plus core polarization(RCICP)method.The static and dynamic electric dipole polarizabilities of the ground state and low-lying excited states are determined.Then,the magic wavelengths of the magnetic sublevel 6s_(1/2,m=1/2)→5d_(3/2,m=±3/2,±1/2)and 6s_(1/2,m=1/2)→5_(d5/2,m=±5/2,±3/2,±1/2)transitions in the linearly,right-handed,and left-handed polarized light are further determined.The dependence of the magic wavelengths upon the angle between the direction of magnetic field and the direction of laser polarization is analyzed.

Genetic dissection of yield-related traits in response to drought stress in common bean

Drought stress severely impairs common bean production.For facilitating drought-resistance breeding in common bean,molecular markers were identified in a genome-wide level marker–trait association study.A panel of 210 common bean accessions showed large variation in 11 agronomic traits at the adult stage(plant height,pod number per plant,seed number per pod,seed number per plant,seed yield per plant,pod length,harvest index,pod harvest index,days to maturity,hundred-seed weight,and seed yield)under two water conditions.The coefficient of variation ranged from 6.21% for pod harvest index to51.00% for seed number per plant under well-watered conditions,and from 4.05% for days to maturity to 40.72% for seed number per plant under drought stress.In a genome-wide association study,119quantitative-trait loci were associated with drought resistance,including 41 adjacent to known loci.Among these loci,12 were found to be associated with at least two traits.Three major loci were identified at Pv01 and Pv02.A set of candidate genes were found that encode MYBs,AREBs,WKRYs,and protein kinases.These results reveal promising alleles that control drought resistance,shedding light on the genetic basis of drought resistance and accelerating future efforts for drought resistance improvement in common bean.

A telomere-to-telomere reference genome provides genetic insight into the pentacyclic triterpenoid biosynthesis in Chaenomeles speciosa

Chaenomeles speciosa(2n=34),a medicinal and edible plant in the Rosaceae,is commonly used in traditional Chinese medicine.To date,the lack of genomic sequence and genetic studies has impeded efforts to improve its medicinal value.Herein,we report the use of an integrative approach involving PacBio HiFi(third-generation)sequencing and Hi-C scaffolding to assemble a high-quality telomere-to-telomere genome of C.speciosa.The genome comprised 650.4 Mb with a contig N50 of 35.5 Mb.Of these,632.3 Mb were anchored to 17 pseudo-chromosomes,in which 12,4,and 1 pseudo-chromosomes were represented by a single contig,two contigs,and four contigs,respectively.Eleven pseudo-chromosomes had telomere repeats at both ends,and four had telomere repeats at a single end.Repetitive sequences accounted for 49.5%of the genome,while a total of 45515 protein-coding genes have been annotated.The genome size of C.speciosa was relatively similar to that of Malus domestica.Expanded or contracted gene families were identified and investigated for their association with different plant metabolisms or biological processes.In particular,functional annotation characterized gene families that were associated with the biosynthetic pathway of oleanolic and ursolic acids,two abundant pentacyclic triterpenoids in the fruits of C.speciosa.Taken together,this telomere-to-telomere and chromosome-level genome of C.speciosa not only provides a valuable resource to enhance understanding of the biosynthesis of medicinal compounds in tissues,but also promotes understanding of the evolution of the Rosaceae.

抵钉座经肛置入法腹部无切口手术与腹腔镜直肠前切除术的对比研究

目的:探讨抵钉座经肛置入法腹部无切口手术(natural orifice specimen extraction surgery,NOSES)与腹腔镜直肠前切除术(laparoscopic anterior rectectomy,LAR)的临床效果比较。方法:回顾性分析2019年1月至2020年1月在菏泽市立医院接受治疗的60例中低位直肠癌患者的临床资料,其中NOSES组(n=30)作为观察组行抵钉座经肛置入法肛门外翻切除标本腹部无切口手术,对照组(n=30)行LAR,对比分析两组术中和术后各临床相关指标。术后随访6~12个月,观察肿瘤复发情况。结果:两组患者手术均顺利完成,无中转开腹病例,两组术中出血量、术中淋巴结清扫数目、术后并发症发生率、肿瘤复发率等差异无统计学意义(P>0.05);NOSES组手术时间、术后疼痛评分、首次下床活动时间、肛门排气时间、首次进食时间、住院时间均优于对照组,差异有统计学意义(P<0.05)。结论:NOSES治疗中低位直肠癌安全可行、效果满意。相比传统腹腔镜手术具有手术时间短、术后疼痛轻、下床活动早、肛门排气早、进食时间早、住院时间短、腹部无切口疤痕、快速康复等优点,而术后并发症及肿瘤复发率无明显增加,值得临床上推广应用。

腹腔镜下胃癌D2根治术联合射频消融应用于胃癌肝转移的临床疗效

目的探讨腹腔镜下胃癌D2根治术联合射频消融肝转移瘤应用于胃癌肝转移的临床疗效。方法选取该院2017年1月-2020年1月收治的可切除胃癌肝转移需行胃癌D2根治术联合射频消融的患者62例,随机分为对照组和观察组,每组各31例。对照组采用开腹胃癌D2根治术联合射频消融治疗,观察组采用腹腔镜下胃癌D2根治术联合射频消融治疗。比较两组患者手术指标、血清肿瘤标志物指标、免疫相关指标和并发症情况。结果对照组术中出血量多于观察组,肠功能恢复时间、住院时间明显长于观察组(P<0.05),手术时间短于观察组(P<0.05);术后两组患者血清甲胎蛋白(AFP)、癌胚抗原(CEA)水平降低(P<0.05),观察组血清AFP、CEA水平均低于对照组(P<0.05);术后两组患者CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+)水平均较术前降低(P<0.05),观察组CD4^(+)、CD4^(+)/CD8^(+)水平明显高于对照组(P<0.05);观察组并发症发生率12.90%低于对照组41.94%(P<0.05)。结论腹腔镜下胃癌D2根治术联合射频消融治疗胃癌肝转移有利于患者术后康复,可明显改善血清肿瘤标志物水平及机体免疫功能,降低围术期并发症发生率。

双眼单焦点与多焦点人工晶状体混搭植入术后视觉质量评估

目的:比较主视眼植入单焦点人工晶状体(SIOL)、对侧非主视眼植入多焦点人工晶状体(MIOL)和双眼均植入SIOL的临床疗效。方法:选取2019-01/2021-01于成都爱尔眼科医院行白内障超声乳化联合IOL植入术的年龄相关性白内障患者60例120眼,主视眼均已植入SIOL,根据对侧非主视眼植入IOL的类型分为三组,其中A组患者18例36眼非主视眼植入MIOL(SBL-3);B组患者19例38眼非主视眼植入MIOL(SN6AD1);对照组23例46眼双眼均植入SIOL。术后3mo,评估并比较三组患者双眼视力及视觉质量。结果:术后3mo,三组患者双眼裸眼和矫正远视力、裸眼中视力及矫正近视力均无差异(P>0.05),A组和B组患者双眼裸眼近视力和矫正中视力均显著优于对照组(P<0.05)。Catquest 9SF-CN量表评分显示,A组和B组患者(11.11±1.323、11.89±1.883分)视觉质量均优于对照组(14.65±1.722分,均P<0.05)。A组、B组和对照组患者脱镜率分别为88.9%、84.2%、39.1%,A组患者脱镜率显著高于对照组(P<0.0167)。结论:白内障患者主视眼植入SIOL、对侧非主视眼植入MIOL(SBL-3/SN6AD1)可获得较双眼均植入SIOL更优的全程视力,术后不良视觉症状少,脱镜率及满意度高。

双通道技术评价两种衍射型多焦点人工晶状体视网膜成像质量

目的:研究两种非球面衍射型多焦点人工晶状体(IOL)视网膜成像质量。方法:回顾性队列研究。选取2017-10/2019-10诊断为单纯性白内障,行超声乳化吸除联合IOL植入155例155眼为研究对象,植入非球面衍射双焦点IOL 54例54眼、非球面衍射三焦点IOL 54例54眼、单焦点IOL 47例47眼做对照组。随访术后6mo,双通道视觉质量分析系统测量散射指数(OSI)、调制传递函数截止频率(MTF cut off)、斯特列尔比值(SR)、100%、20%、9%模拟对比度视力(OV);记录术后裸眼远距离(5m)、中距离(80cm)、近距离(40cm)视力及矫正远视力、矫正远视力基础上的中距离视力和近距离视力;利用VF-14量表进行评分。结果:双焦组和三焦组MTF cut off均低于单焦组(P=0.007、0.043),双焦和三焦组无差异(P=0.445)。三组OSI值无差异(F=1.143,P=0.322),三组SR值无差异(F=3.045,P=0.051)。双焦组和三焦组模拟对比度视力无差异(OV 100%:P=0.974;OV 20%:P=0.713;OV 9%:P=0.947),而双焦和三焦组均低于单焦点组(OV 100%:双焦vs单焦P=0.001;三焦vs单焦P=0.012;OV 20%:双焦vs单焦P=0.002;三焦vs单焦P=0.043;OV 9%:双焦vs单焦P=0.011;三焦vs单焦P=0.029)。三组术后裸眼远视力及矫正远视力均无差异(P=0.054、0.180)。双焦组与单焦组裸眼中视力有差异(P=0.010),三焦组与单焦组、双焦组均有差异(P<0.01)。双焦组和三焦组裸眼近视力无差异(P=0.428),双焦组和三焦组与单焦组均有差异(P<0.01)。三组患者远视力矫正基础上中视力有差异(H=67.176,P<0.01),双焦组与单焦组有差异(P<0.01),三焦组与单焦组和双焦组均有差异(P<0.01)。三组远视力矫正基础上近视力均有差异(H=91.292,P<0.01),双焦组和三焦组无差异(P=0.519),双焦组和三焦组与单焦组均有差异(P<0.01)。三组VF-14表评分有差异(H=71.342,P<0.01),双焦组和三焦组评分无差异(P=0.055),双焦组和三焦组与单焦组均有差异(P<0.01)。结论:双通道视觉系统评估三焦点、双焦点衍射型人工晶状体视网膜成像质量无差别;三焦点较双焦点人工晶状体,可提供更佳的中距离视力。

融合前车轨迹预测的改进人工势场轨迹规划研究

人工势场算法在移动场景中的避撞路径规划很少考虑其与前车未来轨迹的时序耦合影响,基本将每个规划周期内的前车视为静态,通过不同规划周期滚动更新的方式进行准动态路径规划,导致规划路径不够合理、一致性差。本文针对性提出通过时序耦合关联,将前车预测轨迹融入智能汽车路径规划过程。首先构建了改进人工势场算法的引力场及斥力场模型,提出在每个规划周期内,将前车位置在斥力场中根据其预测值进行动态更新;而后提出了基于驾驶意图聚类识别及离散优化结合的前车轨迹长时间预测算法,以及基于运动学模型聚类识别与无迹卡尔曼滤波算法结合的前车轨迹短时间预测算法,再经S函数进行加权融合完成前车轨迹的最终预测。高速驶出及邻车切入等场景下的仿真分析表明,相比于传统的人工势场算法,所提出的改进人工势场动态轨迹规划算法能获得更加合理和一致性更优的规划结果。

改性木质素的制备及对聚丙烯阻燃和抗氧化性能的影响

以棉杆木质素(LG)为原料制备了尿素基改性棉杆木质素(UM-LG)、酯化木质素(EL)、间苯二胺基改性棉杆木质素(ML)3种改性棉杆木质素,并作为聚合物改性剂,添加到聚丙烯(PP)中,研究了不同改性木质素对PP阻燃和抗氧化性能的影响。结果表明,3种改性木质素对PP的阻燃和抗氧化性能都有所提升。PP中添加15%UM-LG后,与纯PP试样相比较,氧化诱导时间延长了52.9%;在200℃、螺杆转速30 r/min、回流10 min下剪切扭矩提高了50.58%。当PP中添加15%ML后,氧指数达到24.9%;从扫描电镜图中可以发现,3种改性木质素的添加使得PP在燃烧过程中形成了炭层,进一步说明,改性木质素增强了PP的阻燃性能;力学性能测试表明,由于改性木质素的添加,PP的力学性能受到一定程度的影响。