A new method of calculating crown projection area and its comparative accuracy with conventional calculations for asymmetric tree crowns

This paper introduces a new method of calculating crown projection area(CPA),the area of level ground covered by a vertical projection of a tree crown from measured crown radii through numerical interpolation and integration.This novel method and other four existing methods of calculating CPA were compared using detailed crown radius measurements from 30 tall trees of Eucalyptus pilularis variable in crown size,shape,and asymmetry.The four existing methods included the polygonal approach and three ways of calculating CPA as the area of a circle using the arithmetic,geometric and quadratic mean radius.Comparisons were made across a sequence of eight non-consecutive numbers(from 2 to 16)of measured crown radii for each tree over the range of crown asymmetry of the 30 trees through generalized linear models and multiple comparisons of means.The sequence covered the range of the number of crown radii measured for calculating the CPA of a tree in the literature.A crown asymmetry index within the unit interval was calculated for each tree to serve as a normative measure.With a slight overestimation of 2.2%on average and an overall mean error size of 7.9%across the numbers of crown radii that were compared,our new method was the least biased and most accurate.Calculating CPA as a circle using the quadratic mean crown radius was the second best,which had an average overestimation of 4.5%and overall mean error size of 8.8%.These two methods remained by and large unbiased as crown asymmetry increased,while the other three methods showed larger bias of underestimation.For the conventional method of using the arithmetic mean crown radius to calculate CPA as a circle,bias correction factors were developed as a function of crown asymmetry index to delineate the increasing magnitude of bias associated with greater degrees of crown asymmetry.This study reveals and demonstrates such relationships between the accuracy of CPA calculations and crown asymmetry and will help increase awareness among researchers and practitioners on the existence of bias in their CPA calculations and for the need to use an unbiased method in the future.Our new method is recommended for calculating CPA where at least four crown radius measurements per tree are available because that is the minimum number required for its use.

Differential modulation of crown allometry and stem growth at gap edges in five European tree species by drought conditions

Background In Central Europe,forests are increasingly affected by various disturbances,resulting in an increasing gap formation in the canopy.In order to support goal-oriented management,more knowledge is required about the acclimation of the crown and its effects on the basal area growth of trees at the edge of a gap.Methods This work compared trees'growth and crown structure at the edge of a transient gap,with a gap size of more than 80m^(2),with trees in the stand that were at least 30m away from the gap.A total of 249 European beeches(Fagus sylvatica L.),Norway spruces(Picea abies L.Karst),Scots pines(Pinus sylvestris L.),oaks(Quercus spp.;Quercus petraea(Matt.)Liebl.,Quercus robur L.),and silver firs(Abies alba Mill.)were examined on long-term experimental plots in southern Germany.Various crown measures were developed and calculated using high-resolution terrestrial laser scanning(TLiDAR)to capture the three-dimensional crown structures.Growth responses to edge conditions were measured based on tree rings.Using linear mixed models,we predict the basal area increment of edge trees relative to trees in the stand under wet and dry soil moisture conditions after the gap formation.Results We identified i)species-specific acclimation of the crown of edge trees after the gap formation,ii)under wet soil moisture conditions a growth increase of 25%–45%for beech,pine,and oak edge trees and growth losses of 5%–60%for spruce and fir and iii)coniferous tree species benefited from the edge position regarding their basal area increment under dry soil moisture conditions and deciduous tree species grew regardless of the soil moisture conditions at the edge of a gap.Conclusion Gaps have a species-specific effect on the habitus and growth of edge trees and can have both positive and negative impacts on silviculture.

Interfacial engineering through lead binding using crown ethers in perovskite solar cells

In the domain of perovskite solar cells(PSCs),the imperative to reconcile impressive photovoltaic performance with lead-related issue and environmental stability has driven innovative solutions.This study pioneers an approach that not only rectifies lead leakage but also places paramount importance on the attainment of rigorous interfacial passivation.Crown ethers,notably benzo-18-crown-6-ether(B18C6),were strategically integrated at the perovskite-hole transport material interface.Crown ethers exhibit a dual role:efficiently sequestering and immobilizing Pb^(2+)ions through host-guest complexation and simultaneously establishing a robust interfacial passivation layer.Selected crown ether candidates,guided by density functional theory(DFT)calculations,demonstrated proficiency in binding Pb2+ions and optimizing interfacial energetics.Photovoltaic devices incorporating these materials achieved exceptional power conversion efficiency(PCE),notably 21.7%for B18C6,underscoring their efficacy in lead binding and interfacial passivation.Analytical techniques,including time-of-flight secondary ion mass spectrometry(ToF-SIMS),ultraviolet photoelectron spectroscopy(UPS),time-resolved photoluminescence(TRPL),and transient absorption spectroscopy(TAS),unequivocally affirmed Pb^(2+)ion capture and suppression of non-radiative recombination.Notably,these PSCs maintained efficiency even after enduring 300 h of exposure to 85%relative humidity.This research underscores the transformative potential of crown ethers,simultaneously addressing lead binding and stringent interfacial passivation for sustainable PSCs poised to commercialize and advance renewable energy applications.

Comparison of Clinical Effects of Au-Pt Based and Ni-Cr Based Porcelain Crowns

Objective To compare the long-term clinical effects of two kinds of crowns and bridges made of porcelain fused to Au-Pt alloy and Ni-Cr alloy. Methods A total of 131 teeth (64 patients) were rehabilitated using porcelain-fused-to-metal crowns, among which 59 were rehabilitated with Au-Pt alloy metal ceramic crown and 72 with Ni-Cr alloy metal ceramic crown. The porcelain fracture, shade, marginal adaptation, gingival discoloration, and gingival status after finishing restoration and 36 months of follow-up were evaluated. Results After 36 months of restoration, porcelain fused to Au-Pt alloy crown showed better clinical effects than porcelain fused to Ni-Cr alloy crown in shade, marginal adaptation, gingival discoloration, as well as gingival status (all P<0.05). Conclusion The Au-Pt alloy ceramic crown is superior to Ni-Cr alloy ceramic crown in long-term clinical effects.

三次CVC、五次CVC及SmartCrown辊形控制特性对比研究

通过对三次连续变凸度(continuously variable crown,CVC)、五次CVC及SmartCrown三种辊形方程进行推导分析,得出了各自的板形控制特性,提出了各自的辊形设计方法。研究表明:三次CVC只具备二次凸度控制能力,控制特性简单;五次CVC可根据二次及四次凸度控制需要灵活设计,凸度比在窜辊过程中并非恒定;SmartCrown四次凸度控制能力受形状角影响,凸度比恒为负值。

An Evaluation of Crown Structure and Site Index to Determine Crown Closure in Eucalyptus urophylla × E. grandis Stands in Guangxi,China

Eucalyptus forests are grown in many parts of the world for their commercial value and use in construction projects. Density management becomes im- portant as a means to attain the management goals in these forests. Changes in canopy and tree crown structure were quantified for Eucalyptus urophylla x E. grandis forests at different ages to determine when canopy closure occurs and the onset of competition begins. Site index was developed for these forests to determine whether site quality affects the canopy structure. Site index had little effect in the forests sampled, with the forest canopy on the better sites becoming slightly more elongated. Based upon crown projection ratio and crown diameter： dbh （diameter at breast height） ratio, it appears that crown closure occurs by age 4 years in these forests. The age at which this occurs was also checked and verified with the evaluation of relative spacing, RS （the ratio of the mean distance between trees to the average dominant height of the stand）. The RS value displayed a rapid decline until age 4 years, and then became relatively flat through age 21 years. The rapid height growth during the first 3 years with no change in density accounted for this rapid decrease. By age 4 years, reductions in the number of trees due to mortality began to have more of an influence on this value, resulting in a more gradual de- cline. The implications for management are discussed.

一种基于五次CVC和SmartCrown复合辊型的板形控制方法

为改善轧机的板形调控能力,在分析连续变凸度CVC辊型和SmartCrown辊型特性的基础上,提出了一种基于五次CVC和SmartCrown的复合辊型的板形控制方法。将五次CVC和SmartCrown辊型在控制板形缺陷方面的特性相结合,采用分解与迭加的方法重新确定其二次和四次凸度及调控能力。通过设计实例和效果分析验证,表明该方法有效改善了五次CVC和AVC辊型因辊径差较大不利于板形控制的缺点。

Calix[4]Crowns类化合物在分离铯中的应用

Calix[4]Crowns类化合物作为超分子识别材料能够有效地分离铯,并能很好地应用在溶剂萃取、液膜萃取、色谱分离等领域。介绍了Calix[4]Crowns类化合物及其复合超分子材料对铯离子的识别和分离效果,为寻求对Cs(Ⅰ)有优异配合能力的Calix[4]Crowns类有机配体结构及相应的功能材料提供参考。

[｛Pt_4(en)_4(NHCO^tBu)_4｝｛Tl(18-crown-6)｝_2](PF_6)_6的合成与晶体结构(英文)

The compound [｛Pt4(en)4(NHCOtBu)4｝｛Tl(18-crown-6)｝2](PF6)6 has been synthesized by a simple one-potmulticomponent reaction. Its structure was determined by X-ray single crystal diffraction analysis. The cation ofthe compound consists of one linearly arranged [Pt4(en)4(NHCOtBu)4]4+ chain and two [Tl(18-crown-6)]+ ions located atthe two ends of the platinum chain. The complex crystallizes in a triclinic P1 with a=1.060 5(1), b=1.252 3(1), c=2.015(2) nm, α=107.430(2)°, β=91.032(2)°, γ=101.910(2)°, V=2.489 6(4) nm3, Z=2, R1=0.074 4, wR2(I>2σ(I))=0.2225, S=1.062. CCDC: 294083.

Research on Crown Grafting of Seedling Cashew Trees

Objective] The study was aimed to improve the yield and quality of cashew. [Method] Through the comparative analysis, the survival rate, new germi-nation and yield characteristics of the cutting stems with different heights by stem grafting and bark grafting. [Result] The best cutting stem height of cashew should be in 100-150 cm, when the number of new germinated shoots was 85.5-87.7. Stem grafting could significantly improve the survival rate of the shooting branch （92.7%）, growth condition of which was better than that of bark grafting, and it also had no clip cortex. The yield of stem grafting was significantly higher than that of bark grafting, and it could reach up to 18.1 kg/plant in 4 years. The branches from stem grafting had significantly better ability in resisting the wind damage than those from bark grafting. [Conclusion] The study provided references for the crown grafting of cashew planting in China.

Smart Crown轧辊轧制钨板过程有限元分析

针对传统轧制工艺轧制钨板过程中,轧辊易损坏、钨板轧废严重等现象,基于有限元分析软件,研究利用Smart Crown轧辊轴向移动轧制钨板,根据要求设计了一款Smart Crown轧辊。从辊形、应力、应变以及磨损方面,分析钨板轧制情况,发现同等轧制条件下,Smart Crown轧辊轴向移动轧制钨板的新工艺优于传统钨板轧制工艺。

Application of the Plate Crown Prediction

The program of the plate crown optimal prediction applied in the plate mill of Wuhan Iron and Steel(Group) Co. Ltd. is described. Optimal prediction is programmed in ALPHA 4000. The original profile, wear, expansion and deformation of work rolls are introduced into the program. The plate crown is controlled by the original profile of work rolls and the draft whose objective is the optimal plate crown. The run schedule is also optimized through the optimal prediction of the plate crown.

TOOTH CROWN DEFORMABLE DESIGN BASED ON DIRECT MANIPULATION OF FFD

A flexible and adaptable design method for the tooth crown is presented based on the direct manipulation of free-form deformation （FFD）. The correct shape of the tooth crown can be obtained by adding, modifying, and deleting constraint points or load points based on stretching and compressing operation. Finally, an example is given to illustrate the method to be efficient.

基于WindowsCE和CROWN集群技术的DTVSP模式

摘 要：基于嵌入式操作系统技术、多媒体数据文件切片方案及网络电视、数字电视标准等提出了基于WindowsCE与Linux集群的DTVSP架构模型，并针对DTVSP模式中客户端功能的实现进行探索，使网络功能、（未来）用户个性化功能与安全性都予以充分的体现；同时使分布式DTVSP的整体功能与事件的管理成为可能。

纤维桩联合不同冠部修复方式修复穿髓型非龋性颈部缺损牙体的力学分析

背景:使用纤维桩修复穿髓型非龋性颈部缺损可以改变牙齿的应力分布,显著降低患牙折裂风险,但关于纤维桩改善牙体抗折性的力学机制及穿髓型非龋性颈部缺损的最佳冠部修复方式尚有争论。目的:综述纤维桩修复穿髓型非龋性颈部缺损后的应力分布模式,在各种受力状态下的抗折能力与断裂模式,以及纤维桩联合不同冠部修复方式的最新研究进展。方法:应用计算机在PubMed和中国知网数据库中检索2008年9月至2023年9月发表的相关文献,英文检索词为“non-carious cervical lesions,endodontically treated teeth restoration,endodontically treated teeth stress distribution”,中文检索词为“非龋性颈部缺损,根管治疗后牙体修复,根管治疗后牙齿应力分布”,最终纳入56篇文献进行分析。结果与结论:穿髓型非龋性颈部缺损根管治疗后,应用纤维桩修复可部分改善牙齿颈部应力,同时不会增加牙根纵裂的风险;使应力分布更加均匀,提高牙齿的抗折性。使用纤维桩修复的非龋性颈部缺损牙齿若折断,其断裂模式显示出有利的、可恢复的或可修复的断裂模式。纤维桩联合瓷贴面或贴面式嵌体可能会成为修复穿髓型非龋性颈部缺损的一种较理想微创修复方法。

Smart Crown技术的研究与应用

介绍了Smart Crown板形控制技术的原理及技术特点,根据Smart Crown辊型曲线方程推导了轧辊等效凸度方程。生产实践证明,使用Smart Crown工作辊后,轧机板形控制能力显著提高,轧辊磨损均匀,工作周期显著延长。

Isolation and Preliminary Identification of Antibacterial Active Substances of Antagonistic Actinomycetes against Peach Crown Gall(Agrobacterium tumefaciens)

[ Objective ] The paper was to isolate and preliminarily identify the antibacterial active substances of antagonistic actinomyeete strain G19 obtained from the soil highly affected by peach crown gall （Agrobacterium tumefaciens）. [ Method] The antibacterial substances of antagonistic actinomycete strain G19 were ex- tracted using protein precipitation method, then isolated and purified using high performance liquid chromatography and medium-pressure preparative chromatogra- phy. Its molecular weight was determined by MALDI-TOFMS method, and the related functional groups were verified through chemical color reaction. [ Result] Seven peptide portions were produced from the antibacterial substances of antagonistic actinomycete strain G19 with the molecular weights of 900 - 1 300 Da after isolation and purification. It could be also inferred that it contained Cys, and carried with H2O and Na＋. Color reaction of functional groups verified that the sub- stance was polypeptide containing glycosyl. [ Conclusion] The result provided basis for the final definition of the structure of antibacterial substances in antagonistic actinomycete strain G19.

罐装饮料的别样风情——访CROWN Asia Pacific Holdings Ltd．总裁约瑟夫·萨拉兹先生

金属包装是中国包装工业的重要组成部分，其产值约占包装工业总产值的10％，其中铝质二片饮料罐在金属包装制品中占重要的地位。金属包装罐迄今已有70多年的历史。20世纪30年代初，美国就已经开始生产啤酒金属罐了，这种三片罐是用马口铁皮制作的，罐体上部呈圆锥状，最上面是冕状罐盖。

新一代CROWN 63节能型散货船

为了应对日益严格的排放标准和环保方面的要求,在严峻的经济环境和残酷的市场中保持竞争力。太平洋造船集团在全球性金融危机爆发之前,就展开了前瞻性的布局,加快了富有竞争力船型的自主研发设计进程。日前,由太平洋造船集团自主研发的CROWN63节能型散货船再传捷报,

Nonlinear mixed-effects height to crown base and crown length dynamic models using the branch mortality technique for a Korean larch( Larix olgensis ) plantations in northeast China

Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and shape.The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots,but crown dynamic models has seldom been constructed.Therefore,this study aimed to develop height to crown base(HCB)and crown length(CL)dynamic models using the branch mortality technique for a Korean larch plantation.The nonlinear mixed-eff ects model with random eff ects,variance functions and correlation structures,was used to build HCB and CL dynamic models.The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China.The results showed that HCB progressively increases as tree age,tree height growth(HT growth)and diameter at breast height growth(DBH growth).The CL was increased with tree age in 20 years ago,and subsequently stabilized.HT growth,DBH growth stand basal area(BAS)and crown competition factor(CCF)signifi cantly infl uenced HCB and CL.The HCB was positively correlated with BAS,HT growth and DBH growth,but negatively correlated with CCF.The CL was positively correlated with BAS and CCF,but negatively correlated with DBH growth.Model fi tting and validation confi rmed that the mixed-eff ects model considering the stand and tree level random eff ects was accurate and reliable for predicting the HCB and CL dynamics.However,the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation,and the fi tting precision of the models was reduced.Therefore,from the point of view of application,we should take care to avoid setting up over-complex models.The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.