Precision and accuracy of sampling methods in thinned Pinus taeda L. stands

Different sampling methods can be used in forest surveys. It is important to know the precision and accuracy of these sampling methods, and which one is the most appropriate in specific conditions of the forest population. The aim of this study was to compare estimates of a forest inventory performed by different sampling methods with forest census results. The sampling methods evaluated were the fixed-area method and the variable-area methods of Bitterlich, Prodan, and Strand. The data were obtained in a 15-year-old thinned stand of Pinus taeda L., located in the municipality of Teixeira Soares, southern Brazil, with a total area of 12.80 ha. Initially, the forest census was carried out, and subsequently, the sample units for each sampling method were distributed in the stand, with a common starting point. The variables used to compare the sample results with the census means were quadratic diameter, number of trees, basal area, and volume, per hectare. Precision and accuracy were evaluated by sampling error and whether the confidence intervals covered the population means, respectively. The fixed-area and Bitterlich methods stood out in precision for all variables analysed. The fixed-area, Bitterlich and Strand methods with proportion to height provided more accurate estimates. The Prodan method provided inaccurate and imprecise estimates for the variables under analysis, except for the quadratic diameter.

VOLUMETRIC MODELING OF Pinus taeda L. FROM ORBITAL IMAGES

This work aimed to investigate the potential of image-derived indices derived from Sentinel-2/MSI images in the volumetric modeling of a stand of Pinus taeda L. located in Bom Retiro, State of Santa Catarina. For this purpose, field data derived from a forest inventory were used, by the fixed area method and simple random sampling with an allocation of 18 circular plots of 400 m². The remotely located data comprised an orbital image from the Sentinel-2/MSI sensor. From this image, 14 average vegetation indices per plot were calculated. These indices were correlated with the volume by plot (m³ 0.04 ha-1) derived from the inventory. The indices with the best correlation for volume by plot (m³ 0.04 ha-1) were the Generalized Difference Vegetation Index (GDVI) and Adjusted Soil Vegetation Index (SAVI) with 0.39 and 0.36, respectively. The best regression model completed using these VIs estimated the volume by plot with R² controls of 0.9402 and Syx of 1.44%. The use of spectral indices generated from Sentinel-2/MSI sensor data enabled the volumetric estimate of the Pinus taeda L. stand, not revealing differences between the volume accumulated by forest inventory and by orbital images. However, it is worth pointing out that new tests be carried out on other forest species and with medium to high spatial resolution sensors.

Load capacity of the board grillage with two stringers under ice loading

Снизить повреждаемость бортовых перекрытий при ледовых нагрузках можно за счет совершенствования расчетных зависимостей по оценке их несущей способности. Далеко не всегда такие зависимости, приводимые в справочных изданиях, дают верные рекомендации из-за не вполне ясного характера распределения нагрузок в сложных статически неопределимых системах. В справочнике по СМК приводится расчетная зависимость, позволяющая определить несущую способность регулярного перекрытия с двумя стрингерами при действиии локально распределенной нагрузки в пределах прямоугольника. Цель данной работы заключалась в оценке несущей способности реального бортового перекрытия ледокола типа Wind с помощью МКЭ при параметрах ледовой нагрузки, определяемой рекомендациями Морского Регистра РФ, и последующем сравнении полученных результатов с расчетами по теоретической зависимости, приведенной в справочнике. Полученные данные показали, что зависимость в справочнике для оценки несущей способности перекрытия дает удовлетворительно согласующиеся с МКЭ результаты после соответствующего уменьшения числового коэффициента в ней. При анализе несущей способности перекрытия варьировались шпация, толщина обшивки, высота стенок стрингеров и площадь приложения нагрузки. Установлено, что текучесть наблюдается в опорных сечениях шпангоутов и посредине их пролета, а из-за большой ширины присоединенного пояска обшивка у контура перекрытия практически никогда не течет. Полученные МКЭ результаты показали наличие обратно пропорциональной зависимости между предельной нагрузкой и шпацией при фиксированной площади нагружения. Отмечено, что увеличение толщины обшивки несущественно влияет на величину предельной нагрузки при остальных неизменных параметрах перекрытия. Выполненные расчеты позволяют кроме предельной нагрузки оценить также и величины прогибов при упругопластическом деформировании перекрытий, которые затруднительно подсчитать аналитически. To low damage of the board grillages under ice loading is possible by improving analytical relations on estimation of their load capacity. Not always such relations, bringing in manuals, give true recommendations because of complex character of the loads distribution in static indeterminate systems. Im manual on ship structural mechanics is giving analytical relation for determination of load capacity of regular grillage with two stringers under action of localy distributed load in rectangular area. Purpose of this study is to estimate load capacity of real board grillage of icebreaker of type Wind with help of FEM under parameters of ice load recommended in Maritime Register of RF, and following comparison of obtained results with calculation on analytical relation, given in manual. Obtained results show that relation in manual for estimation of load capacity of grillage give satisfactory results corresponding to FEM only after corresponding reducing of numerical coefficient in it. Under analysis of load capacity of grillage, it was changing frame space, thickness of plating, depth of stringers and area of application of load. It was estimated that most loaded zones of frames are their sections near supports and in the mid-span. Because of big width of associated plate the plating near contour of grillage is never yielding practically. Results obtained by FEM show existence of inversely proportional relation between the limit load and space framing under fixed area of loading. It was noticed that increasing of the plating thickness influent not essentially on value of the limit load under all other parameters of grillage unchangeable. Performed calculations allow to estimate limit load and value of deflections under elasto-plastic deformation of grillage, which is difficult to calculate analytically,

Generating stochastic trajectories with global dynamical constraints

We propose a method to exactly generate Brownian paths x c (t) that are constrained to return to the origin at some future time t f , with a given fixed area A f = ∫ 0 t f d t x c ( t ) under their trajectory. We derive an exact effective Langevin equation with an effective force that accounts for the constraint. In addition, we develop the corresponding approach for discrete-time random walks, with arbitrary jump distributions including Lévy flights, for which we obtain an effective jump distribution that encodes the constraint. Finally, we generalise our method to other types of dynamical constraints such as a fixed occupation time on the positive axis T f = ∫ 0 t f d t Θ x c ( t ) or a fixed generalised quadratic area A f = ∫ 0 t f d t x c 2 ( t ) .

Differentiation of Dust Holding Capacity of Poplar Crowns

One of the key parameters of comfort and compliance with sanitary standards for cities is dustiness of atmosphere. Plantings of representatives of the poplar genus (Populus L.) become a reliable means of optimizing this parameter. We have studied the effectiveness of using different types of poplars in urban plantings, taking into account the differentiation of crown sections by the ability to deposit dust on the surface of the leaf apparatus. The object of research is 8 species from different sections of the poplar genus, typically found in urban plantings of the Nizhny Novgorod region. We considered the influence of three independently of one another factors on the dispersion of dust holding capacity: species-specificity of poplars (8 gradations); lighting conditions of crown due to its orientation relative to the cardinal directions (4 gradations); height characteristics of the crown tier location (3 gradations). Dust was washed off from 100 leaves of each poplar species with their fixed area. The highest amount of dust in the flushes was observed for silver poplar (257.60±5.05 mg), and the lowest – for black poplar (117.69±3.65 mg) and Pópulus nígra var. itálica (105.69±2.90 mg). Oneway ANOVA confirmed the significance of differences between the species for all parameters of dust holding capacity. Three-way ANOVA showed the influence of leaf surface locations in different parts of the crown on the efficiency of dust deposition by representatives of different species. Species appeared to be the most important in the distribution of dust deposited on the leaf surface of shoots in different parts of the crown; the share of its influence was 37.65±0.51 %. The effect of crown lighting conditions was also well measurable; its share was equal to 20.45±0.28 %. The influence of the crown tier height was noticeably less; its share reached 7.19±0.21 %. The listed factors are little related to each other, and their interaction generated a negligible effect: 6.67±4.54 %, Fh2 = 1.47, significance is reliable at 5 % level (F05 = 1.41) and unreliable at 1 % level (F01 = 1.61). For citation: Besschetnova N.N., Besschetnov P.V. Differentiation of Dust Holding Capacity of Poplar Crowns. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 48–64. DOI: 10.37482/0536-1036-2021-5-48-64

The Markov gap for geometric reflected entropy

The reflected entropy SR(A : B) of a density matrix ρAB is a bipartite correlation measure lower-bounded by the quantum mutual information I(A : B). In holographic states satisfying the quantum extremal surface formula, where the reflected entropy is related to the area of the entanglement wedge cross-section, there is often an order-N2 gap between SR and I. We provide an information-theoretic interpretation of this gap by observing that SR− I is related to the fidelity of a particular Markov recovery problem that is impossible in any state whose entanglement wedge cross-section has a nonempty boundary; for this reason, we call the quantity SR− I the Markov gap. We then prove that for time-symmetric states in pure AdS3 gravity, the Markov gap is universally lower bounded by log(2)ℓAdS/2GN times the number of endpoints of the cross-section. We provide evidence that this lower bound continues to hold in the presence of bulk matter, and comment on how it might generalize above three bulk dimensions. Finally, we explore the Markov recovery problem controlling SR− I using fixed area states. This analysis involves deriving a formula for the quantum fidelity — in fact, for all the sandwiched Rényi relative entropies — between fixed area states with one versus two fixed areas, which may be of independent interest. We discuss, throughout the paper, connections to the general theory of multipartite entanglement in holography.

The two-sphere partition function in two-dimensional quantum gravity at fixed area

We discuss two-dimensional quantum gravity coupled to conformal matter and fixed area in a semiclassical large and negative matter central charge limit. In this setup the gravity theory — otherwise highly fluctuating — admits a round two-sphere saddle. We discuss the two-sphere partition function up to two-loop order from the path integral perspective. This amounts to studying Feynman diagrams incorporating the fixed area constraint on the round two-sphere. In particular we find that all ultraviolet divergences cancel to this order. We compare our results with the two-sphere partition function obtained from the DOZZ formula.

Area-perimeter duality in polygon spaces

Two natural foliations, guided by area and perimeter, of the configurations spaces of planar polygons are considered and the topology of their leaves is investigated in some detail. In particular, the homology groups and the homotopy type of leaves are determined. The homology groups of the spaces of polygons with fixed area and perimeter are also determined. Besides, we extend the classical isoperimetric duality to all critical points. In conclusion a few general remarks on dual extremal problems in polygon spaces and beyond are given.

Power Maximization and Turbulence Intensity Management through Axial Induction-Based Optimization and Efficient Static Turbine Deployment

Layout optimization is capable of increasing turbine density and reducing wake effects in wind plants. However, such optimized layouts do not guarantee fixed T-2-T distances in any direction and would be disadvantageous if reduction in computational costs due to turbine set-point updates is also a priority. Regular turbine layouts are considered basic because turbine coordinates can be determined intuitively without the application of any optimization algorithms. However, such layouts can be used to intentionally create directions of large T-2-T distances, hence, achieve the gains of standard/non-optimized operations in these directions, while also having close T-2-T distances in other directions from which the gains of optimized operations can be enjoyed. In this study, a regular hexagonal turbine layout is used to deploy turbines within a fixed area dimension, and a turbulence intensity-constrained axial induction-based plant-wide optimization is carried out using particle swarm, artificial bee colony, and differential evolution optimization techniques. Optimized plant power for three close turbine deployments (4D, 5D, and 6D) are compared to a non-optimized 7D deployment using three mean wind inflows. Results suggest that a plant power increase of up to 37% is possible with a 4D deployment, with this increment decreasing as deployment distance increases and as mean wind inflow increases.

Improved Unequal-Clustering and Routing Protocol

We propose improved unequal-clustering and routing protocol (IUCR) protocol to solve both of these problems jointly. IUCR provide fixed area clustering derived from transmission range of network nodes. This clustering also develops strong network backbone that provides fail-over-proof routing. Efficient routing path is achieved by finding minimal hop-count with availability of alternate routing path.