检索结果-南通市图书馆

Variable retention forestry in European boreal forests in Russia

Ecological Processes 2019年第1期8卷 424-434页

作者： Ekaterina Shorohova Sergey Sinkevich aleksandr kryshen Ilkka Vanha-Majamaa Forest Research Institute of the Karelian Research Centre of the Russian Academy of Sciences Pushkinskaya str.11Petrozavodsk 185910Russia Saint-Petersburg State Forest Technical University Institutsky str.5Saint Petersburg 194021Russia Natural Resources Institute Finland(Luke)Latokartanonkaari 9FI-00790 HelsinkiFinland

We explored whether,and to what extent,variable retention(VR)forestry has been applied in European boreal forests in northwestern *** survey revealed VR since *** 1910 and the 1960s,the statistics showing how much was retained are largely ***,for example,in the 1950s,on a large scale in the Republic of Karelia,up to 200-ha-sized harvesting areas,18–33%,were retention patches with a mean growing stock of 30–40m3 ha−*** the fellings defined as“incomplete clear fellings,”which were the most common final felling type at that time,11–40%of the growing stock was *** the 1960s and the early 1990s,with more efficient harvesting and skidding techniques,conventional clear fellings with a much lower amount of retention were *** about the regeneration of harvested areas gradually led to smaller(maximum 50 ha)harvesting areas and the increase of silvicultural *** now,to ensure natural regeneration,patches of understory and 20–25 seed trees(i.e.,ca.15–25m3)per ha have been left permanently in harvesting ***-scale retention for protecting ecosystem functions and biodiversity was legislated in 1978 by preserving key biotopes up to 1000 ha in *** 2001,promoted by forest certification,the key biotopes,such as paludified forest patches,buffers around water bodies,and habitats of red-listed species,have also been retained in harvesting areas,together with a dispersed retention of different *** estimates of the amount of key biotopes are largely ***,estimates of 1–13%in harvesting areas and 23%in whole managed landscapes have been *** applied during the last century has emulated natural disturbances and created diverse uneven-aged forest structures with high amounts of diverse coarse woody *** conclude that an analysis of past and current retention practices is essential for estimating the global role of Russian *** decisions on the general direction

关键词： Biological legacies Nature conservation Biodiversity Clear felling Key biotopes Coarse woody debris,Silviculture Dispersed and aggregated retention

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Correction to: Variable retention forestry in European boreal forests in Russia

引用

Ecological Processes 2019年第1期8卷 484-484页

Correction to:Ecol Process https://***/10.1186/s13717-019-0183-7 In the original publication of this article(Shorohova et al.,2019),the figure captions of Figs.2,3 and 4 are *** should be changed to:‘Fig.2 The share of different forest management categories in different regions of NW Russia(Regional 2017,2018).Red lines denote the borders between the *** lines denote the borders between vegetation zones(Bonh et al.2000,2003).NB northern boreal zone,MB middle boreal zone,SB southern boreal zone,HB hemiboreal zone.

关键词： states. retention forest

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Predicting impact strength of perforated targets using artificial neural networks trained on FEM-generated datasets

引用

Defence Technology（防务技术） 2024年第2期32卷 32-44页

作者： Nikita Kazarinov aleksandr Khvorov Saint Petersburg State University Saint Petersburg 199034Russia Higher School of Economics Saint Petersburg 190121Russia

The paper considers application of artificial neural networks(ANNs)for fast numerical evaluation of a residual impactor velocity for a family of perforated PMMA(Polymethylmethacrylate)*** ANN models were trained using sets of numerical results on impact of PMMA plates obtained via dynamic FEM coupled with incubation time fracture *** developed approach makes it possible to evaluate the impact strength of a particular target configuration without complicated FEM calculations which require considerable computational ***,it is shown that the ANN models are able to predict results for the configurations which cannot be processed using the developed FEM routine due to numerical instabilities and errors:the trained neural network uses information from successful computations to obtain results for the problematic cases.A simple static problem of a perforated plate deformation is discussed prior to the impact problem and preferable ANN architectures are presented for both *** insight into the perforation pattern optimization using a genetic algorithm coupled with the ANN is also made and optimized perforation patterns which theoretically enhance the target impact strength are constructed.

关键词： Machine learning Impact Dynamic fracture FEM Mesh distortion Optimization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Changes in the growth of Scots pine(Pinus sylvestris L.)stands in an urban environment in European Russia since 1862

引用

Journal of Forestry Research 2023年第5期34卷 1279-1287页

作者： aleksandr V.Lebedev Department of Agricultural Meliorations Forestry and Land OrganizationRussian State Agrarian University-Moscow Timiryazev Agricultural AcademyTimiryazevskaya49MoscowRussia 127434

A century and a half ago,in the European part of Russia(Moscow),forest scientists established the first long-term observations of forests,many of which are under observation to the present *** the twentieth century,climate changes and,due to industrial development,forest areas were under air *** on observations from 157 sites,this study shows that the growth and density of Scots pine(Pinus sylvestris L.)have decreased by the end of the twentieth *** environment has changed,and the growth and development of plantations has *** yields(-34%stand volume)and their life expectancy(on average 50 years)have *** changes are critical for forestry and for the management of forests in urban *** to the decline in growth,ecosystem functions by urban forests has *** order to increase the sustainability of urban forests and the provision of ecosystem services,it is preferable to create multi-species stands with a complex structure.

关键词： Forest stand Scots pine Stand growth Urbanized environment Human footprint

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Oscillations of an Inviscid Encapsulated Drop

引用

Fluid Dynamics & Materials Processing 2020年第4期16卷 761-771页

作者： aleksandr Shiryaev Ishlinsky Institute for Problems in Mechanics of the Russian Academy of Sciences Moscow119526Russia

The problem relating to the small-amplitude free capillary oscillations of an encapsulated spherical drop is solved theoretically in the framework of asymptotic *** are supposed to be inviscid and *** formulas derived are presented for different parameters of the inner and outer liquids,including densities,thickness of the outer liquid layer,and the surface and interfacial tension *** frequencies of oscillation of the encapsulated drop are studied in relation to several“modes”which can effectively be determined in experiments by photo and video *** results are presented in terms of oscillation frequencies reported as a function of the mode number,the spherical layer thickness and the relation between the(surface and interfacial)tension *** is revealed that the influence of the liquids’parameters(and related variations)on the drop oscillation changes dramatically depending on whether oscillations are“in-phase”or“out-of-phase”.Frequencies for“in-phase”type oscillations can be correlated with linear functions of the shell thickness and the relative values of interfacial tension coefficient whereas the analogous dependencies for the“out-of-phase”type oscillation are essentially non-linear.

关键词： Encapsulated drop oscillation frequencies inviscid fluid

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Crystal structure and thermal expansion of perovskites containing uranium(VI) and rare-earth elements

引用

Journal of Rare Earths 2009年第1期27卷 4-11页

作者： aleksandr Knyazev Anna Ershova Nikolai Chernorukov Nizhny Novgorod State University

By the method of high-temperature reactions in solid phase, compounds with the general formula MⅡ（AⅢ2/3U1/3）O3（MⅡ=Sr, AⅢ=Sc, In;MⅡ=Ba, AⅢ=Sc, In, Y, Nd-Lu） were *** structures（space groups Fm 3 m and Pnma） were refined by the Rietveld method and morphotropic transition in Ba（Ln2/3U1/3）O3 on the border of Gd-Tb was *** means of high-temperature X-ray diffraction, phase transitions were studied and thermal expansion coefficients were determined.

关键词： perovskite uranium X-ray diffraction Rietveld structure thermal expansion rare earths

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Photochemical degradation of nonylphenol in aqueous solution: The impact of pH and hydroxyl radical promoters

引用

Journal of Environmental Sciences 2013年第7期25卷 1326-1330页

作者： aleksandr Dulov Niina Dulova Marina Trapido Department of Chemical Engineering Tallinn University of Technology

The degradation of nonylphenol （NP） in aqueous solution with UV, H202/UV, and Fenton/photo-Fenton processes was studied. The efficacy of direct and hydrogen peroxide photolysis proved to be dependent on the pH value. The addition of H202 to UV treatment improved NP degradation. The application of UV photolysis and the H202/UV system at pH 7 resulted in low pseudo first-order rate constants at 104 sec1 . In the experiments at elevated pH values the pseudo-first order rate constants increased to 103 sec1 . The efficacy of the Fenton process was lower in comparison with UV and hydrogen peroxide photolysis. The addition of UV irradiation to the H202/Fe2＋ system substantially improved NP degradation efficacy. In terms of performance, the photo-Fenton process was similar to the H202/UV process. The most favourable process for complete nonylphenol degradation considering both operational cost and treatment efficacy was H202/UV at pH 11 and 250 μmol/L H202 .

关键词： AOPs endocrine disrupting compound photo-Fenton process photolysis UVC radiation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Utilization of Extrinsic Fabry-Perot Interferometers with Spectral Interferometric Interrogation for Microdisplacement Measurement

引用

Journal of Electronic Science and Technology 2020年第1期18卷 59-75页

作者： Leonid Liokumovich aleksandr Markvart Nikolai Ushakov Higher School of Applied Physics and Space Technologies Peter the Great St.Petersburg Polytechnic UniversitySt.Petersburg 195251

The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers(EFPIs). The analysis of attainable microdisplacement resolution is performed and the analytical equations describing the dependence of resolution on parameters of the interrogation setup are derived. The efficiency of the proposed signal processing approaches and the validity of analytical derivations are supported by experiments. The proposed approaches allow the interrogation of up to four multiplexed sensors with attained resolution between 30 pm and 80 pm, up to three times improvement of microdisplacement resolution of a single sensor by means of using the reference interferometer and noisecompensating approach, and ability to register signals with frequencies up to 1 kHz in the case of 1 Hz spectrum acquisition rate. The proposed approaches can be used for various applications, including biomedical, industrial inspection, and others, amongst the microdisplacement measurement.

关键词： Absolute measurement dynamic measurement Fabry-Perot interferometer least-squares methods optical fiber sensors resolution analysis resolution enhancement sensor multiplexing spectral interferometry

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental Study of Liquid Metal Flow for the Development of a Contact-Less Control Technique

引用

Fluid Dynamics & Materials Processing 2024年第7期20卷 1553-1564页

作者： aleksandr Poluyanov Ilya Kolesnichenko Laboratory of Technological Hydrodynamics Institute of Continuous Media Mechanics of the Ural Branch of Russian Academy of Science(ICMM UB RAS)Perm614018Russia

The article presents an experimental study on the flow of an eutectic gallium alloy in a cylindrical cell,which is placed in an alternating magnetic *** magnetic field is generated by a coil connected to an alternating current *** coil is located at a fixed height in such a way that its plane is perpendicular to the gravity vector,which in turn is parallel to the axis of the *** position of the cylinder can vary in height with respect to the *** forced flow of the considered electrically conductive liquid is generated due to the action of the localized electromagnetic *** is assumed that under the action of the alternating magnetic field,the liquid is heated uniformly,and the resulting heat is quickly absorbed by the forced flow,so that liquid free convection can be *** experiment is carried out using an ultrasonic Doppler *** transducer is installed in the axially located cylinder sluice and the other transducer is placed in the near-wall *** to the results,a velocity profile,corresponding to a two-tori flow pattern can be hardly obtained in the low frequency range of the power ***,this is possible in the high frequency *** average velocity profiles depend essentially on the location of the coil relative to the *** spectral analysis of velocity signals shows that the amplitude of the velocity pulsations is comparable to the average value of the flow *** experimental results and their verification through comparison with numerical calculations are intended to support the development of new methods for reducing the intensity of vortex flows during the electromagnetic separation of impurities through an electromagnetic induction mechanism(able to produce an electromotive force that displaces particles).

关键词： Ultrasonic doppler velocimeter electrically conductive medium azimuthal pinch experiment in liquid metal magnetohydrodynamics

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Coronary revascularization in the elderly with stable angina

引用

Journal of Geriatric Cardiology 2015年第5期12卷 555-568页

作者： Kirill Lenarovich Kozlov aleksandr Andreevich Bogachev Laboratory of Age-Related Clinical Pathology Department of Clinical Gerontology and Geriatrics St. Petersburg Institute of Bioregulation and Gerontology Northwestern Branch Russian Academy of Medical Sciences Saint-Petersburg Russia Department of Cardiovascular Medicine Kirov Military Medical Academy Saint-Petersburg Russia

A proportion of elderly with coronary artery disease is rapidly growing. They have more severe coronary artery disease, therefore, derive more benefit fi＇om revascularization and have a greater need for it. The elderly is a heterogeneous group, but compared to the younger cohort, the choice of the optimal revascularization method is much more complicated among them. In recent decades, results has improved dramatically both in surgery and percutaneous coronary intervention （PCI）, even in very old persons. Despite the lack of evidence in elderly, it is obvious, that coronary artery bypass surgery （CABG） has a more pronounced effect on long-term survival in price of more strokes, while PCI is certainly less invasive. Age itself is not a criterion for the selection of treatment strategy, but the elderly are often more interested in quality of life and personal independence instead of longevity. This article discusses the factors that influence the choice of the revascularization method in the elderly with stable angina and presents a complex algorithm for making an individual risk-benefit profile. As a consequence the features of CABG and PCI in elderly patients are exposed. Emphasis is centered on the frailty and non-medical factors, including psychosocial, as essential components in making the decision of what strategy to choose. Good communication with the patients and giving them unbiased information is encouraged.

关键词： Angina Cardiopulmonary bypass Coronary artery disease Stents The elderly

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：