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INNO 2/2014 2014

STRUCTURE AND PROPERTIES OF FIR (ABIES BORISII – REGIS MATTF.) AND SPRUCE (PICEA EXCELSA LINK) AND THEIR INFLUENCE ON WOΟD IMPREGNABILITY

Автори: Elias Voulgaridis, Генка Блъскова, Costas Passialis

Резюме

Spruce and fir wood is important for Greek and Bulgarian forestry and wood industry. Durability of spruce and fir mature heartwood is low and both species are refractory to impregnation - spruce wood is poorly or not permeable, while fir wood is poorly to moderately permeable. The low permeability and the resistance of fir and spruce wood to impregnation are attributed to its specific anatomical – characteristics and properties. This work presents the structural characteristics and properties, summarises those anatomical characteristics which are related to impregnation processes and looks for new methods to improve fir and spruce wood permeability. Surface drilling of wood by laser beams might improve their permeability to preservatives and widen the uses of fir and spruce in exterior conditions.

Ключови думи: spruce, fir, wood structure, wood properties, permeability

EN Version

STUDY OF THE WOOD ACOUSTIC PROPERTIES OF THE USING A MODIFIED RESONANT METHOD

Автори: Николай Бърдаров

Резюме

Some of the unique properties of the wood are the acoustical. Together with its elastic properties they characterize this material to a great extent. Wood is unique with its characteristic of having high elasticity and damping of the low density.

This work examines the basic acoustic properties, as obtained by resonance method. Specimens of spruce wood, arranged in groups of varying density, are examined. The speed of sound, dynamic modulus of elasticity, acoustic constant and damping are set. Relations between the values of these properties in longitudinal and transverse oscillations are sought. The effect of density on the properties of the wood is established.

Ключови думи: wood, sound velocity, dynamic modulus of elasticity, acoustic constant

EN Version

A MODEL OF THE STATICALLY INDETERMINATE TENSION IN THE BLADE OF A HORIZONTAL BANDSAW

Автори: Стефан Стефанов, Валентин Атанасов

Резюме

An original model is proposed for determination of the statically indeterminate tension (internal tensile force) in the blade (saw band) of a horizontal bandsaw with a tensioning spring mechanism. The statically indeterminate problem is solved in a way missing in the bandsaw references but required by the Strength of Materials science: based on a deformation compatibility equation. In the case considered, in that equation the spring parameters are also involved. The model proposed is a generalization of a published previous model (Stefanov 2013) regarding a vertical bandsaw blade tension.

Ключови думи: bandsaw blade, horizontal bandsaw, spring mechanism, statically indeterminate tension

EN Version

APPLYING OF MS EXCEL 2010 FOR 2D COLOUR VISUALIZATION OF TEMPERATURE FIELDS IN LOGS DURING THEIR DEFROSTING PART 1. SEQUENCE OF PROCEDURES FOR THE CREATION OF 2D COLOUR DIAGRAMS USING MS EXCEL 2010

Автори: Ненчо Делйски, Иван Христов, Веселин Брезин, Ladislav Dzurenda, Радослав Милчев, Славчо Соколовски

Резюме

A methodology for the creation of colourful 2D diagrams using MS Excel 2010, illustrating the temperature distributions in the longitudinal sections of frozen logs during different moments of their defrosting, has been suggested in this paper. For the creation of the diagrams numerical results have been used, which represent the solutions to a non-linear mathematical model of the logs’ defrosting process. These numerical results are presented in files in the .txt format before their processing with the software of MS Excel 2010 aiming at the creation of the 2D colourful diagrams.

Ключови думи: 2D visualization, temperature fields, wood defrosting, oak logs, MS Excel 2010

EN Version

APPLYING OF MS EXCEL 2010 FOR 2D COLOUR VISUALIZATION OF TEMPERATURE FIELDS IN LOGS DURING THEIR DEFROSTING PART 2. 2D VISUALIZATIONS OF THE TEMPERATURE FIELDS IN OAK LOG IN DIFFERENT MOMENTS OF THEIR DEFROSTING

Автори: Ненчо Делйски, Иван Христов, Веселин Брезин, Ladislav Dzurenda, Радослав Милчев, Славчо Соколовски

Резюме

In the first and at the beginning of the second part of this work the methodology for creation of 2D colourful diagrams has been described as thematically-oriented sequence of the used procedures of MS Excel 2010. In this part of the work the methodology has been applied for the preparation of 2D colourful diagrams of temperature distribution in the longitudinal sections of a frozen oak log during its defrosting. The methodology can be used for the preparation of various 2D diagrams for the change of temperature, moisture, and other fields in the volume of different materials in the cases when the diagrams are created using extensive numerical results from models, adequately describing the studied processes.

Ключови думи: 2D visualization, temperature fields, wood defrosting, oak logs, MS Excel 2010

EN Version

CALCULATION OF OPERATIONAL STRESSES IN BLADES OF HORIZONTAL MOBILE BANDSAWS

Автори: Валентин Атанасов, Стефан Стефанов

Резюме

As a continuation of two accompanying papers of ours, in this paper calculation is done relating to operational stresses in blades of horizontal mobile bandsaws as a part of their operational characteristics. In the case of tensioning the blade by a spring mechanism, when the problem of the tensile forces and stresses is statically indeterminate, our solution (from the first accompanying paper) applies. This requires iterations which are programmed in an excel-file. In it, a number of formulas for stress calculation are programmed which are derived in our second accompanying paper. Several types of stress-components, and stress conditions, are involved. A series of additional computational results are obtained automatically with varying the input data in the excel-file. Stress oscillograms have been drawn, as well. They show that, under equal other conditions, the horizontal bandsaw blade is more threatened by fatigue than a vertical bandsaw blade.

Ключови думи: bandsaw blades, horizontal mobile bandsaws, operational tensile forces and stresses in saw bands, automation of stress calculations

EN Version

EXPLORING THE ENERGY PERFORMANCE OF WOOD CHIPS FROM SALIX VIMINALIS – KLON TORDIS

Автори: Константин Маринов, Живко Гочев, Martin Lieskovský, Michal Ferenčík

Резюме

The article presents the methodology and results of an experimental testing of the calorific value and ash content of wood chips, used as a fuel for heating and electricity plants. The wood chips was extracted from willows’ short rotation plantation of Salix Viminalis – klon Tordis. Studies were conducted in the “Department of Forest Harvesting, Logistic and Amelioration” of the Technical University in Zvolen, R of Slovakia. Wood chips produced from Salix Viminalis, klon Tordis indicates a high gross (20,597 MJ.kg-1) and net calorific value of dry mass (19,255 MJ.kg-1) under the specific production conditions. Naturally dried wood has a relative humidity Wr = 11,3 % and according to ISO 1928:2011 it has a clean net calorific value 16,907 MJ.kg-1. This gives grounds to assume that the wood produced from such an energy plantation will have high energy characteristics and will satisfy the market for energy chips.

Ключови думи: wood chips, willow, calorific value, ash contents

EN Version

THE ROLE OF SHAPE AND COLOUR IN CREATING THE VISUAL IDENTITY OF FURNITURE

Автори: Красимир Савчев

Резюме

The visual identity of a furniture piece allows it to stand out from others with similar function. It makes it easily recognizable and memorable, which largely enhances its aesthetic qualities. Color and shape are two of its key elements. 

The paper examines visual identity, its basic components and the relationship between them. The participation of color and shape in visual identity formation for easily memorable furniture pieces is analyzed.

Ключови думи: visual identity, color, shape, furniture

EN Version

TENSILE STRENGTH IN DIFFERENT DIRECTIONS OF LAMINATED PLYWOOD MADE FROM BEECH VENEERS

Автори: Violeta Jakimovska Popovska, Borche Iliev

Резюме

Тhe aim of the research presented in this paper is to study the tensile properties at different directions of experimental plywood.

For this research nine-layered plywood is made. The model is made from peeled beech veneers with thickness of 1,2; 1,5; 2,2 and 3,2 mm.

Pure water-soluble phenol-formaldehyde resin is used as plywood binder.

The tensile strength of the plywood panel is tested in five directions, i.e., parallel and perpendicular to the face grain, and at the angles of 22,5º; 45º and 67,5º to the face grain of the panel.

Coefficients of the equality of the tensile strength in different directions of the plywood model is calculated trough polar diagram made on the basis of the obtained data for the tensile strength at different angles to the face grain of plywood. The coefficient of mass quality is calculated too.

The research results showed that the experimental plywood model meet and exceed the defined values of tensile strength in accordance with the requirements of the standard for load-bearing plywood for use in construction.

Ключови думи: laminated plywood, beech veneers, tensile strength, coefficient of equality of tensile strength, coefficient of mass quality

EN Version

GROSS DOMESTIC PRODUCT AS A DEVELOPMENT FACTOR FOR THE MANUFACTURE OF WOOD AND WOOD PRODUCTS AND FURNITURE PRODUCTION IN THE REPUBLIC OF MACEDONIA

Автори: Mira Stankevik Shumanska

Резюме

Gross Domestic Product (GDP) is one of the most important macroeconomic indicators for the developed level and the economic growth and development dynamic of the each country. GDP in the Republic of Macedonia has increase tendency with average annual rate (AAR) from 7,4 % for the period 2006–2011. GDP per capita follow that trend with the AAR from 7,2 %. Parallel with the increase of the total GDP has grow and for the value added in the manufacturing with the AAR from 4,5 % and also in the furniture production with AAR from 1,7 % for the same period. The value added at manufacture of wood and wood products has negative trend with AAR from -7,7 %. The average annual value added of the manufactory of wood and wood products participates with 1, 5 % in the average annual value added of the total manufacturing, respectively with 0,2 % in the average annual GDP. The average annual value added at furniture production participates with 2,0 % in the average annual value added of the manufacturing and with 0,3 % in the average annual GDP for the analyzed period.

Ключови думи: Gross Domestic Product, Gross Domestic Product per capita, value added, manufacture of wood and wood products, furniture production

EN Version

COMPARATIVE ANALYSIS BETWEEN THE DESTRUCTIVE BENDING MOMENTS OF END AND T-SHAPE CORNER JOINTS OF DETAILS FROM SOLID CHESTNUT WOOD WITH TWO TYPES OF CROSS SECTION

Автори: Georgi Gruevski, Борислав Кючуков

Резюме

A comparative analysis has been done on the experimentally found destructive bending moments in the loading of bending of the most commonly used end and T – shape corner joints of details from solid chestnut wood with two types of cross section of the details – 50 x 25mm and 50 x 30mm.

It has been found, that the type of joints and the thickness of the joining details have a definite impact on their destructive bending moments.

With the increase of the thickness of the details from 25 to 30 mm (with 20 %), the destructive bending moments in the loading of bending of the end glued and dismountable corner joints increase respectively with around 28 % and with 33 %, and of the T – shape corner joints – with around 23 % and around 17 %.

It is recommended that the found out destructive bending moments in the loading of bending and the most commonly used end and T – shape corner joints of details from solid chestnut timber with cross section 50 x 25mm and 50 x 30 mm be taken into consideration in the choice of the type of joints in the sitting furniture construction.

Ключови думи: corner joints of details from solid chestnut wood; destructive bending moments in loading of bending; sitting furniture

EN Version

COMPARATIVE STUDY ON ULTIMATE TENSILE STRENGTH OF SOME T-SHAPE CORNER JOINTS OF STRUCTURAL ELEMENTS OF SOLID BEECH WOOD WITH CROSS SECTION OF 50 x 25 mm

Автори: Борислав Кючуков, Georgi Gruevski, Васил Живков

Резюме

In this work, the ultimate tensile strength of some T-shape corner joints of structural elements of solid beech wood with cross section 50 x 25 mm used in the construction of seating furniture is investigated. It has been found that with reference to the value of ultimate tensile strength, the glued T-shape corner joints are arranged in the following descending series: with stub mortise and tenon; with wedged mortise and tenon; with stub mortise and tenon and dowel, with dowels. With reference to the value of the ultimate tensile strength the dismountable end corner joints are arranged in the following descending series: with two connectors with screw and cross dowel; with two one-piece connectors “Confirmat”. It is recommended that the results from this research can be utilized when calculating the dimensions of seating furniture.

Ключови думи: corner joints for structural elements, ultimate tensile strength, solid beech wood

EN Version

STUDY ON BENDING STRENGTH OF END CORNER DETACHABLE JOINTS OF STRUCTURAL ELEMENTS MADE OF PLYWOOD

Автори: Ралица Симеонова

Резюме

The study presents the results from the research carried out on bending strength of end corner detachable joints of structural elements made of beech veneer plywood. The bending moment under compression bending test has been established. The highest bending strength was achieved with Universal connector and Confirmat 7 x 50 and 7 x 70 mm and the lowest bending strength is typical of joints with bolt and nut and two types of eccentric connectors. It has been established that joints made of beech veneer plywood have higher strength compared to the same type of joints made of beech solid wood.

It is recommended that the comparative data of bending strength are taken into consideration when choosing the type of joints in furniture constructions.

Ключови думи: furniture construction, plywood, joints, bending strength, bending moment

EN Version

METHODS FOR STIMULATING THE CREATIVE SEARCH

Автори: Десислава Ангелова

Резюме

The design methods that stimulate students’ creative process and contribute to the rapid generation of ideas have been studied in this article.

The aim of this report is to demonstrate the effectiveness of the methods and their application in the team student tasks.

The applied methods stimulate the creative thinking by eliminating the mental blocks. These methods are characterized by the prominent role of the visual thinking in the construction of associations. This makes them extremely important for the design process, since the designer should be able to visualize his ideas.

Ключови думи: design methods, education of design, team work, associations

EN Version

THE CONTINUING EDUCATION IN THE FOREST INDUSTRY –A PREREQUISITE FOR INNOVATION

Автори: Диана Иванова, Теодора Обретенова

Резюме

In terms of the enhanced process of globalization and in the context of establishing a knowledge- based economy, the need for lifelong learning and continuing education is growing. Changes in management, organization of work processes, market and customer requirements, mean constant training and qualification. The Continuing education is insensibly becoming a prerequisite for the increased innovation activity of firms. In this regard, it is very important to determine the right approach for research and identifying training needs. This paper aims to provide the theoretical and practical aspects of the problem "Continuing education in Forest Industry”.

Ключови думи: knowledge- based economy, lifelong learning, continuing education, innovation, forest industry, training needs

EN Version

GREEN GROWTH FINANCING

Автори: Natalia Khutorova, Valentin Shalaev

Резюме

This article describes the definition of green finance as the broad range of funding for environment-oriented technologies, projects, industries or businesses. There is the analyze of the state of green financemarket. The problems and prospects are identified. It was noted the increasing role of financial instruments in the transition to low-carbon and climate-resilient development.

The conclusion is:greening economic growth is the only way in which sustainable, inclusive development can be achieved. Many countries have seen the benefits of green growth, anddeveloping countries are taking a clear leadership role in various low carbon initiatives and are using domestic policy mechanisms.

Ключови думи: green growth financing, green finance, climate bonds, low carbon economy

EN Version