HOW TO CHOOSE THE BEST WOOD FOR DECKING AND CLADDING?
Miha Humar, Boštjan Lesar, Davor Kržišnik
The importance of wood in the building sector is increasing. Predominantly wooden facades and cladding are exposed to a variety of degradation factors. To prevent wood decay, we need to select the appropriate wood species, protection or modification method.
In order to assess the durability of different wood species, a model house was constructed in Ljubljana in October 2013. The structure was clad with a waterproof and vapor-open membrane. The wooden facade has a protective and esthetic
function. It consists of 22 different materials used for this and similar applications in this region. The façade elements are arranged horizontally and screwed to the vertically arranged wooden elements treated with Cu-ethanolamine. In
addition to untreated wood (spruce, larch, beech, English oak, sweet chestnut, pine sapwood and heartwood, linden, ash), the materials were given four different treatments: Copper ethanolamine impregnation (Silvanolin®), montan wax impregnation
(Silvacera®), acrylic surface coating (Silvanol® Lazura B) and thermal modification (Silvapro® Wood). The cross-section of the façade elements is 2.5 × 5.0 cm. The terrace boards in front of the house were made of the same materials. Wood
moisture sensors from Scanntronik (Germany) were installed in the respective model objects. They were placed at 120 positions and connected to the Gigamodul, which allowed measurements of the wood MC between 6% and 60%. The decay and moisture
content of decking boards and cladding elements were regularly monitored. In addition, the positive effect of thermal modifications and water repellent treatments on the outdoor behavior of the materials studied was revealed, as well as
the synergistic effects between moisture performance and fungal durability. During the first year of exposure, there was no decay to the decking boards of the model house in Ljubljana. In the second year, the first signs of decay developed
in the sapwood of spruce, beech and pine. After seven years of exposure, there was no decay on the cladding, while the decking boards were severely affected. This shows how important the construction details are. Spruce wood was completely
degraded, followed by beech and Scots pine sapwood. At least minor decay occurred in all of the wood species except thermally modified wood, which was also treated with copper-based wood preservatives or wax. In general, thermally modified
wood performed better than naturally durable species (oak, sweet chestnut). The results indicate that the best durability is found in wood species with good water exclusion efficiency and natural durability.
TOWARDS ERGONOMIC WORKING - MACHINE LEARNING ALGORITHMS AND MUSCULOSKELETAL MODELLING
Franz Suess, Maximilian Melzner, Sebastian Dendorfer
Ergonomic workplaces lead to fewer work-related musculoskeletal disorders and thus also reduce sick days. Evens so there are guidelines such as those from the National Institute for Occupational Safety and Health who provide values during occupational activities it still remains a major challenge to quantify the individual biomechanical loading in real world scenarios. In addition to physical stress, psychological stress causes an increased prevalence of muscle tension and back pain and thus interacts with biomechanical loading. Under laboratory conditions, the biomechanical loads due to physically demanding activities can be determined using musculoskeletal models. Similarly, the change in muscle activity due to psychological stress can be recorded. However, a direct application to real working conditions is difficult and hardly possible. In this study we used a novel approach for a possible implementation by utilizing a combination of experimental data and machine learning models to investigate the general feasibility of these algorithms to predict and incorporate a subject-specific stress-induced MA response. 41 subjects performed trunk flexion/extension cycles with and without exposure to cognitive stress lasting 120 seconds. A dynamometer set and recorded the motion, moment, and angle. EMG sensors recorded six main lower back muscles. This provides in total 28297 data points to train a gradient boost tree (GBT) and deep neural network (DNN). GBT and TNN models are able to predict the activation pattern dependent on the input parameter but with a different precision level. Despite a number of limitations in this study, the results clearly demonstrate that the combined musculoskeletal and mental load can be considered in ergonomic analyses and that the demonstrated methodology could serve as a basis for novel ergonomic workplace designs by applying the technology directly to workers in, for example, wearable-based setups.
ENERGY EFFICIENT EMBEDDED SYSTEMS AND THEIR APPLICATION IN WIRELESS SENSOR NETWORKS
Embedded systems are specialised electronic systems that perform limited number of fixed operations and are used in many application areas. Such systems are based on using microprocessors for their implementation. Embedded systems are usually part of other systems where they are embedded into some embedding systems. They have to be efficient in electrical energy consumption, size of program code, time of operation, weight and cost. Embedded systems are inexpensive and are used in almost every electronic product or other electronic systems. Many embedded systems are mobile systems supplied by batteries and the available electrical energy must be used efficiently as much as possible. One of application areas where embedded systems are used and where minimal consumption of energy is required are battery powered wireless sensor networks. The methods for reduction of energy consumption and for power management in embedded systems are considered and described in the paper. The accent is given on design and application of energy efficient embedded systems in wireless sensor networks and on possibilities to reduce energy consumption in such systems. The methods for energy harvesting, that are very attractive and very useful in wireless sensor networks applications, are also considered and described. One practically implemented battery supplied wireless sensor network for application for environmental data acquisition and monitoring in agriculture is described in the paper.
ALTERNATIVE CONCEPT IN STRUCTURAL ANALYSIS EDUCATION - AXISVM® X6 FEM SOFTWARE -
This paper is a short review on the preferable concept in Structural Analysis education by use of FEM software. It is recognized that good "educational purpose" FEM software includes a pre-processor with intuitive graphically aided user interface that enable simple and efficient geometrical modeling of structural topology, as well as fast and easy training. Also, this category of software should have powerful solver-processor with sophisticated numerical modeling possibilities and post-processor with various types of analysis results presentation.
Hungarian software company "InterCAD" developed FEM software AxsVM® which fulfils above mentioned and much more performances in professional and scientific area. Therefore AxisVM® is embedded in curriculum of subject "FEM Modeling in Structural Analysis" on Department of Civil Engineering and Geodesy - Faculty of Technical Sciences, University in Novi Sad, Serbia.
RECENT TRENDS AND DEVELOPMENT OF PROTECTIVECLOTHING, FOOTWEAR AND EQUIPMENT FOR FIREFIGHTERS
Anica Hursa Šajatović
In extreme working conditions, such as firefighters exposed to high temperatures, a flash fire, fog, water and dust, as protection protective clothing, footwear and equipment are used. All type of clothing, footwear and equipment are functionally designed, taking into account the safety and protection of users, as well as comfort, compatibility with all parts of the protective equipment, simple use and maintenance. Paper describes recent trends and new development of protective clothing, footwear and equipment as well as smart and intelligent protective clothing which applying innovation and integrating new technologies in textiles. Innovation and new technologies applied in textiles will give great opportunities in the future for developing and applying protective clothing and footwear for various uses, including protective personal equipment for firefighters.