bluuebunny/crossref_metadata_2025 huggingface dataset:
New Tendency of Machine Tool Study Based on Virtual Machining Software Applied at University of Oradea
Authors: Bungău Constantin , Ganea Macedon , Pancu Rares
Published: August 2014

The present paper work shows the efforts of the research group from University of Oradea on the introduction into the educational program at all the levels (bachelor, master and PhD) of the newest method of the machine tool study. By these methods is need to understand the educational stages ( engineering for constructive parts, the machining on CNC milling centre up to 5 axes simultaneous, machining of very complexes parts, the programming of the CNC units, the using of the most advanced CAM software, the programming of the robots into the flexible manufacturing cell, etc.). On the other hand we include here the research activity about the improvement of the performances of the entire flexible cell from University of Oradea laboratory by increasing of the technological experiences. It is necessary to mention that the UO-01 flexible manufacturing cell, based on the horizontal milling centre TMA-AL 550, both were developed by own efforts (retrofitting) at University of Oradea in our faculty (Faculty of Management and Technological Engineering) having the contribution of our research group. The entire concept of these new methods is based on virtual simulation into the 3D space of the functioning in real time of all the components at every technological case. For these targets all the components were modeled at 1:1 ratio in 3D space, including the movements of their movable parts.
Simplified Calculation of the Eccentric Press Stiffness
Authors: Demeč Peter , Palaščáková Dominika
Published: August 2014

The article deals with the simplified calculation of the stiffness of the eccentric press frame. The described method applies to the solving of problem a mathematical identification of condition parameters in the press frame the transfer matrix method (TMM), which is in essence a matrix form of initial parameters method. This method is suitable for mechanical systems with continuously distributed mass in space while the cross-sections along the entire length of the system are not constant.
Implementation of Computer System for Support of Technological Preparation of Production for Technologies of Surface Processing
Authors: Svetlík Jozef , Baron Petr , Dobránsky Jozef , Kočiško Marek
Published: August 2014

This paper describes attributes of newly designed variant approach of computer support system of technological preparation of production. Knowledge system for automation of production of technological documentation was developed for technology of surface processing of metal. The paper describes the design of coding system for sorting mechanical parts into groups with similar mechanical parts, either by their shape, dimensions or used technology. Subsequently, it points out to attribute of the system – uploading and modification of sample technological documentation.
Characterization of the Positioning Accuracy and Precision of MEMS Die Servoing Using Model-Based Visual Tracking
Authors: Matúšek Ondřej , Hotař Vlastimil , Laurent Guillaume J. , Tamadazte Brahim , Clevy Cedric
Published: August 2014

This work deals with an automated micro-assembly of MEMS die holders using a 3D visual servoing approach. Visual positioning which was used is based on eye-to-hand tracking principle. The 3D poses of the MEMS are supplied in a real-time by a 3D (CAD) model-based tracking algorithm. Having executed the visual servoing the accuracy and repeatability of this method was examined. The micro-assembly process was performed and the accuracy calculated according to ISO 9283. The achieved accuracy was 0.345 μm and repeatability was 4.3 μm. The rotation accuracy was less than 0.13°.
The Structural of the Basic Module for Construction of Modular Machines
Authors: Turisová Renata , Svetlík Jozef
Published: August 2014

The current situation in the field of automation requires increasingly sophisticated flexible and adaptive solutions. Construction of modular machinery appears to be an effective tool to meet these requirements. Solution of design layout module with rotary motion linkage is designed for machines with unlimited rotary motion, based primarily on a modular concept. The main advantage of the proposed system is the possibility to compile from one module type the machines with different movement possibilities and degrees of freedom of movement for unrestricted use of the possibility of rotation of two adjacent modules, each associated rotary motion linkage.
Simple Image Processing Algorithms for Robot Navigation in Unknown Environment
Authors: Duchoň František , Králik Martin , Babinec Andrej , Hubinský Peter
Published: August 2014

This article deals with simple image processing algorithms which are used for navigation of the robot in unknown environment. In the beginning of the article image processing procedures used in these algorithms are defined. The transformation of coordinate system of camera to robot’s coordinate system is introduced. The main body of the article consists of the definition of L-K optical flow method used in proposed visual odometry system. Article also contains the parameter settings of the used methods. Emphasis in these algorithms has been placed on simplicity and speed, so that they can be carried out in real-time. Algorithms have been verified on several scenarios.
A Mobile Robot Path Tracking Method Based on Fuzzy Logic and Artificial Emotion
Authors: Li Shao Yong
Published: August 2014

Design a subsection fuzzy controller for autonomous mobile robots based on location sensors. First section the controller produced some fuzzy output and part of the output was used for setting up an emotion factor called E. In the second section, E has an effect on the controller, and the mobile robot can move more like a car being driven by human. As the fuzzy controller is down to subsections, each of the section has a simpler fuzzy rule table. The simulation experiment data showed that this kind of control method for path tracking could fit the path better with short response time and strong robustness. It was more flexible and effective on processing different corners during tracking compared to conventional fuzzy control method.
Multi-Legged Robot that Can be Assembled by Two-Wheeled Self-Balance Robots
Authors: Li Shuo Hui , Song Xiang
Published: August 2014

In this paper, a multi-legged robot that can be assembled by self-balance robots that have two multi-degree-of-freedom limbs with wheel installed on the end of each limb is proposed. This type of robot has a more efficient way to travel all kinds of territory: not like normal muti-legged robots which has to use legs to move on flat surface like a roads, this type of robot can move like vehicle using wheels on the end of its legs; and not like two wheels self-balance vehicles which cannot travel on rocky surface, this type of robot can use multi-degree-of-freedom limbs to walk on complex surface. And by separate to several single robots, this type of robot can move through some narrow territory. And by combined as a multi-legged robot, this type of robot can transport much heavier payload than a single self-balance robot.
On the Development of Precision Seeder Intelligent Monitoring System Controlled by Single-Chip Microcomputer
Authors: Yin Qing Yong
Published: August 2014

The development of precision seeder is still in an initial stage in China. Most seeders are mechanical and semi-precision sowing, and intelligent monitoring and controlling systems also have great shortage. This paper discusses intelligent seeding monitoring, fertilizer box and seed box margin monitoring, and bellows pressure monitoring. The main feature of this system is that it adopts modularity, sensor with high-sensitivity and wireless transmission technology for convenient maintenance, which greatly improves the reliability of the system, and provides a feasible scheme for the development of precision seeder.
Detecting Technology for External Anticorrosive Coating Defects of Buried Pipelines
Authors: He Xing Zheng
Published: August 2014

The external anticorrosive coating is the shelter for preventing buried steel pipelines from corrosive damage. Many pipelines face severe corrosive problems because of the performance decrease of the coating, especially during long-term services. This situation usually causes safety accidents. Periodic inspection to the coating is an important way to ensure running safety. Aimed at the detecting technology, the methods for locating the pipelines and the means of on-line defects detecting with no excavation for the coating were studied and introduced. The ways for direction detecting, depth measuring and location coordinates detecting were pointed out. The basic principles of data analysis were also outlined. The various influences coming from external environment factors to the detecting results were analyzed.
Finger Recognition and Tracking Algorithm Based on Single Optical Camera
Authors: Nan Rui , Yang Ming Li
Published: August 2014

A new synthesis method of fingertip detection based on single camera is proposed, which effectively reduces the amount of computation while not relying on hardware performance too much. It provides portability as well because single camera is easy to get in contemporary devices, such as mobile phone. The main idea is to use the curvature of fingertip as a feature to distinguish the tip-part of finger in tracing the motion of hand. The Camshift algorithm is used to track the whole hand to diminish the detective region. The skin-color extraction method is used as an auxiliary part to enhance the ability of discriminating hand from background, which also helps to weaken the interferences produced by brightness of hand surface. Finally a serial frames is used to examine the performance of the new method. With the tracking part and the fingertip recognition part being tested respectively, the result indicates the performance clearly.
Study about Recognition of Digital Meter Dial Reading Based on SVM
Authors: Tu Zhen Yuan , Ning Fang Hua , Yu Wu Jia
Published: August 2014

In practice, it is difficult for Support Vector Machine (SVM) to have a relatively high recognition rate as well as a quite fast recognition speed. In order to resolve this defect, in this paper we build a SVM classification model combining numerical characteristics. We use readings of rotary natural meters as the test temple, do positioning, preprocessing, feature points extracting, classifying and other series of operations to the numeric region of the dial. Then with the idea of cross-validation, we keep doing parameter optimation to SVM. At last, after making a comprehensive contrast of the effects which numerous performance factors make on the experimental outputs, we try to give our explanation of the outputs from different perspectives.
Analysis of Sequences Harmonics Measurement Impact Using Potential Transformers Grounded through Ferroresonance Eliminator
Authors: Chen Yi Huang , Li Yu Chao , Wu Jie , Liu Kai Pei
Published: August 2014

This paper has carried on the theoretical analysis and experimental research on the different impacts of positive, negative and zero sequence harmonic voltage measurement using three single-phase potential transformers with neutral point grounded through a ferroresonance eliminator. First, the influences of the different excitation characteristics among the three PTs and the non-linear excitation characteristics of a single-phase PT on different sequences harmonic voltage measurement are analyzed theoretically. Then the physical experiment platform has been designed, and the experiments of three-phase PTs on different sequences harmonic voltage measurement are carried on. The experiment results verified that the influences of three-phase PTs on different sequences harmonic measurement are not the same at this grounding mode.
Calculation of Self-Healing Contract Resistance of Metallized Film
Authors: Kong Zhong Hua , Wu Li Gang , Tong Chun Ya , Luo Zai Fei
Published: August 2014

Abstract. Self-healing is an interesting property of metallized capacitors. contract resistance is importance to self healing. In the paper contract resistance is calculated with different diameters of hole and different thickness of metal layer. The larger is radius of hole, the less is contract resistance. The thicker is metal layer, the less is contract resistance.
Research on the Image Enhancement Algorithm of Pointer Instrument under Inadequate Light
Authors: Zhang Lu , Zhang Jin Lin , Rui Ting , Wang Yue , Wang Yan Nan
Published: August 2014

For image processing, the recognition of pointer instrument’s reading by computer vision highly depends on brightness. An image enhancement algorithm based on homomorphic filtering and histogram equalization is proposed in order to reduce the impact of low-light conditions on images of pointer instrument. It combines the methods of spatial with frequency domain, which enhances the image contrast and highlights the image details as well. Compared with the traditional method, the experiments show that the proposed method can eliminate the effect of inadequate light and also perform well in enhancing the image quality.
SINS Alignment Using Velocity Matching and Simplified Cubature Kalman Filter
Authors: Ran Chang Yan , Cheng Xiang Hong , Wang Lei
Published: August 2014

This paper proposes a novel nonlinear alignment method for the strapdown inertial navigation system (SINS). The method uses the simplified cubature Kalman filter (CKF) and velocity matching. The system equations are the navigation equation, the Euler angle differential equations and the inertial sensor measurement error models. The system equations are nonlinear, whereas the measurement equations are linear. The CKF is simplified under the condition of the linear measurement equations. The time updating cycle and measurement updating cycle are different. Finally inertial measurement unit experimental data are used to do alignment. The results show that the proposed method can effectively obtain an accurate initial attitude within a short time, thus also be considered a new and simple addition to the kit of solutions for SINS alignment.
Research on Anti-Saturation Attack Model of Ship Formation for Anti-Ship Missile Targets
Authors: Zeng Jia You , Zhong Jian Lin , Xie Yu Peng , Fan Xiao Lei
Published: August 2014

Basing on spatial characteristic of ship formation, numerical characteristics of anti-ship missile (ASM) shooting stream and the dynamic combat process, cooperative models including detection, interception region and confrontation of ship formation to anti-ship missiles were built. The method to calculate numbers of ASM needed to form the saturation attack was deduced. Simulation results show that intensity of ASM is the main factor to influence anti-saturation ability of ship formation, and launching multiple air-defense missiles for each ASM in a salvo can improve anti-saturation ability of ship formation effectively.
Computer Aided Optimal Design and Dynamic Analysis of Piezoelectric Braille Display Cell
Authors: Yeh Fung Huei , Tsay Huoy Shyi , Yang Chung Chieh
Published: August 2014

In this paper, the optimum design and dynamic analysis of a new type of piezoelectric Braille display cell are studied by computer aided engineering software. At first, the design parameters of piezoelectric actuator are analyzed by finite element method to determine the position of fixed end and minimum voltage to actuate 0.7mm displacement and 15g output force. Then, the optimum design is performed according to the electric displacement 0.7mm, output force 15g, actuator length, position of fixed end and minimum voltage. Finally, Braille display cell is analyzed by dynamic simulation software. It shows that actuators take 0.0002 sec to upward achieve 0.7 mm displacement. The result of optimum design is reasonable in this paper which can be the reference for related research.
Dynamic Performance and Structural Optimization of Large-Scale Machine Table
Authors: Chen Zai Liang , Deng Luo Hong , Jing Cong
Published: August 2014

Designed new table for large floor boring and milling machine, used ANSYS to optimize the structure of the table as a whole. According to the contours of removable material the materials which can be removed, obtained the inner ribs layout of table and the sand holes location of rib plate. Dynamic optimization variables on basic ribs cell, studied the effect of steel lattice structure parameters influenced on the natural frequency of the lattices and the related parameter of lattices influenced on whole table, to get the ideal rib lattice structure after optimizing again. Optimized bench can reduce quality, increase rigidity and dynamic performance.
Experimental Study of Compliant Mechanism Considering Thermal Effect
Authors: Hou Wen Feng
Published: August 2014

In this paper, an ultra-precision positioning stage is introduced. The finite element method is used to establish the theoretical model, and the strain test system of experiment is established. The system includes the static strain test and the dynamic strain test. The test system contains the software and hardware system. The software system includes the static strain measurement software of DH3816, the programmable constant temperature and humidity chamber control software TEMI300, and the dynamic strain test system developed from NI Labview. The hardware system contains industrial personal computer (IPC), piezoelectric (PZT) actuator, static strain gauge of DH3816, strain amplifier of YE1817, NI USB-6009 multifunction data acquisition card, strain gauge, programmable temperature and humidity chamber, and precision positioning stage. The experimental test is carried out to examine the theoretical analysis considering thermal effect. Experimental results and analytical results indicate that whether the stresses increase or decrease linearly or nonlinearly depend on the function of the temperature to the time during the transient response same as the stresses increase or decrease linearly during the steady response under uniform temperature change. The dynamic responses of platform are affected by the temperature change, and it is essential to consider thermal effect when analyzing compliant mechanisms.
Research on Inverse System Decoupling of Three-Axis Flight Simulator Based on the High-Speed Rotation Missile
Authors: Yan Xin Ying , Mo Bo , Li Yang Hua
Published: August 2014

This paper researches on the kinematics and dynamics of coupling for three-axis flight Simulator based on the high-speed rotation missile. Firstly, to define station body coordinate and the positive direction of rotation according to three-axis flight Simulator based on the high-speed rotation missile, and then the mathematical coupling model is established. Secondly, multivariable nonlinear mathematical model can be decoupling, while substituting the parameters quality attribute analysis solved by ProE into the mathematical model. Lastly, the decoupled linear equations and the decoupling solutions based on inverse system method were given, and then to finish the simulation and to analysis the simulation results.
Modeling, Analysis and Synthesis of Hybrid System: A Review
Authors: Mahemuti Pazilat , Yang Lian , Luo Lai Long
Published: August 2014

This paper proposes a framework of modeling, analyzing, and controlling systems represented by interdependent physical laws, logic rules, and operating constraints, denoted as hybrid system. Based on the basic concept and characteristics of hybrid system, we classify the conventional models including hybrid automaton, hybrid Petri nets, mixed logic dynamics, et al. We introduce the method of stability analysis, and point out the main difficulties in optimization and control of hybrid systems. Finally, the further research directions are prospected.
PLC Based Bottling Process Control System
Authors: Zhu Jin Wen
Published: August 2014

As the use of automation increases in the manufacturing industry as well as other industrial environments, more programmable logic controllers (PLCs) are used in these areas to increase reliability and flexibility, reduce cost, and increase maintainability. In this proposed paper, a basic of PLC in automation environments is introduced and a bottle filling and packaging process control implemented by using Allen Bradly CompactLogix PLC is discussed.
Precise Control of High-Speed BLDCM Based on BP Neural Network
Authors: He Ying , Mo Bo , Li Yang Hua
Published: August 2014

Brushless DC Motor (BLDCM) is a strongly nonlinear systems, which means that we can’t get a satisfactory result by the traditional PID Controller. This paper presents an improved BP Neural Network algorithm with adaptive adjustment of learning rate and range adjustment of the output. At last, using MatLab/Simulink to verify the algorithm that it has better control precision and adaptability.
Research on Supervisory Control and Data Acquisition System Based on Stacker
Authors: Ji Jing , Cao Shao Zhong
Published: August 2014

This paper aims at the current field of industrial control of stacker networking and intelligence, presents a supervisory control and data acquisition system. In VC++.NET environment, transfer Mitsubishi MX component by Mitsubishi FX3U Ethernet module implements the computer and Mitsubishi FX3U series PLC communication, to reach the remote real-time data acquisition and supervisory control ,to provide a visual interface for the user.
Research on Triple-Loop Control of BLDCM Based on Fuzzy PID
Authors: Li Yang Hua , Mo Bo , He Ying , Zhang Wen Jing
Published: August 2014

The brushless DC motor (BLDCM) has many advantages. This paper first analyzes the work principle of BLDCM and the control methods of the fuzzy PID, then designs a triple-loop controller based on the fuzzy PID BLDCM, finally makes a comparison of the traditional PID method and this new method. The experiment result shows that the result of the PID controller based on the BLDCM is much better than the traditional PID controller, the BLDCM improves the performance both on the step response of the position and the sinusoidal steady state response.
Study on Direct Torque Control of Brushless Doubly-Fed Machine Based on Discete Space Vector Modulation
Authors: Yang Wen Jie
Published: August 2014

The paper introduces Working mode of brushless doubly-fed machine（BDFM） and mathematical model in the d-q coordinates for BDFM，a strategy of discrete space vector modulation in direct torque control for BDFM has been Proposed 。The paper uses Matlab / Simulink to model and simulate the system of the direct torque control for brush double-fed motor based on discrete Space Vector Modulation.Simulation results prove that the discrete space vector modulation technique can reduce the torque ripple of traditional direct torque control system for BDFM, and improve waveform of current and Flux of Control winding.
The Development and the Field Application of the On-Line Dry Ice Washing Vehicle System
Authors: Li Zhen Zhu , Jiang Feng , Zheng Jun Jie , Zou Jian Ming , Tu Chang Geng , He Xiao Xin , He Zi Zheng , Zhou Wen Jun
Published: August 2014

Abstract: In order to wash the polluted substation insulator quickly and safely, so as to improve the reliability of substation systems, an on-line dry ice washing system which would be applied in 220 kV voltage level was developed. Based on the results of the indoor simulation tests which provided the optimal washing parameters, the on-line dry ice system was developed. Moreover, a trial test was run in a 220 kV substation belonging to Hubei State Grid. The test results show that the vehicle system can meet the requirements of on-line washing tasks in 220 kV substation. Therefore, the washing system features advanced technology, excellent performance, and promotional value.
Research on Alarming Device for Warp Stop Motions of Computer Sewing Machines
Authors: Sun Dong , Ni Jun Fang , Wang Jia Shan , Feng Zhi Hua
Published: August 2014

Owing to spandex silks are very thin and transparent, it is very hard to spot the broken warp without alarm during sewing or weaving. Therefore, the key to solve the problem is to shutdown and alarm timely when warps break. The ways and principles of common warp stop are analyzed in this paper, a new type of warp stop motions is developed for textile purposes to avoid inconveniences and malfunctions of the traditional method. Alarming rate and stability can be improved effectively by the compact and lightweight design of drop stitches, controlling system with converting functions as well as the modified testing, protection, reset.
Study on Risk Assessment of Power Transformer Based on Life Cycle Quality Information
Authors: Bi Tian Shu , Chen Jin Meng
Published: August 2014

It has significant impact on the safe operation of the power grid for large scale power transformer. The technique is complex, and the manufacture process is long. The users always take the manufacturing supervision on spot as the quality control method. The quality is determined during the manufacturing process. The quality defects may cause serious safe problems. It has important significance to strengthen the risk assessment and prevention. The quality defects of power transformer are classified based on the fault tree analysis theory. The quality defects of power transformer from the manufacturing supervision of State Grid Corporation of China (SGCC) in 2012 are analyzed as examples. The manufacturing process has multiple layers and factors. The index system for comprehensive evaluation of transformer is put forward. A risk assessment model for power transformer based on fuzzy synthetic evaluation is built. The example shows that the method can estimate the risk effectively. It can provide feasible decision basis for the risk management and maintenance.
The Application of Air-Entraining Admixtures for the Development of Heat Insulating Moulded Refractory Concretes
Authors: Bednárek Jan , Šoukal František , Novotný Radoslav , Lang Karel
Published: August 2014

The thesis deals with the possibility of kaolin suspensions specific weight lowering using air-entraining agents. These agents are usually used as concrete admixtures. The goal of the thesis is to verify an alternative possibility of creating porous structure in kaolin suspensions in order to prepare heat insulating moulded refractory concretes without using lightweight fillers.
The effect of several air-entraining agents was compared, after that the dosage of agent and mixing conditions were optimized. The stabilization of prepared foams and practical application of selected agents were also part of the thesis.
Cyclic Weathering of Wood - Polymer Composite Modified by a Fly Ash Admixture
Authors: Benešová Anna , Vanerek Jan , Drochytka Rostislav , Havlíčková Kateřina
Published: August 2014

The aim of this paper was to evaluate the influence of cyclic weathering degradation on strength properties of wood-polymer composite modified by varying amount of fly ash filler admixture. Test specimens prepared according to EN ISO 527 were cyclic exposed to moist environment and action of frost and increased temperature. After termination of degradation process, relevant characteristics were evaluated to optimize the amount of fly ash admixture and describe its function in the structure of the composite.
Treatment of Timber by Nanofiber Fabric with Biocide Compound
Authors: Rácová Zuzana , Hrochová Petra , Ryparová Pavla
Published: August 2014

Dry rot fungus (Serpula lacrymans) is wood-decaying fungus. It grows frequently in our territory and it causes big damages on structures. Remediation of damaged structures is very difficult, sometimes impossible, therefore it is necessary to study preventive protection against dry rot fungus. PVA nanofibred fabrics with synthetic and natural biocidal additives were used for this experiment. Filter papers soaked in dopes with biocidal substances were other materials used for this experiment. Pieces of nanofiber fabrics and pieces of filter papers soaked in dopes were placed to Petri dishes with broth. Small cuts of dry rot fungus were placed around them. This experiment was performed in conditions, which promote the growth of dry rot fungus. Growth of dry rot fungus was studied.
Limestone Sludge in the Brick Body
Authors: Sokolař Radomír , Vodová Lucie , Šveda Mikuláš
Published: August 2014

Influence of limestone sludge (generated during the washing process of limestone crushed aggregates) with high content of CaO in the form of calcite on the properties of brick body made from non-calcareous sludge (from the washing process of quartz sand) as a basic plastic brick clay was determined. Presence of calcite very distinctly influenced the firing process and properties of fired body. Limestone sludge decreases firing shrinkage, bulk density and coefficient of thermal conductivity of the brick body after the firing in the range of 850 – 950 °C. Higher modulus of rupture and water absorption is typical for fired bodies with limestone sludge addition. Most of these improvement are caused by the formation of anorthite only in the bodies based on the limestone sludge.
Application of Metakaoline in Autoclaved Aerated Concrete Technology
Authors: Koutný Ondřej , Opravil Tomáš , Pořízka Jaromír
Published: August 2014

In these days, autoclaved aerated concrete research points to the utilization of alternative raw materials such as metakaoline. An effort is made to improve the mechanical and related heat-insulation properties of the products without significant change of present technology and price. This work studies the effect of metakaoline, as an alternative raw material to Portland cement, on final properties of autoclaved aerated concrete, especially the effect on the volume weight and compressive strength. Quantitative and qualitative mineralogical composition, especially the presence and the amount of Tobermorite and Xonotlite were observed by XRD and TG-DTA-EGA methods.
Impact Resistance of Steel Fibre Reinforced Thin-Walled Shell Structures
Authors: Rehacek Stanislav , Huňka Petr , Citek David , Šimúnek Ivo
Published: August 2014

Fibre-reinforced composite materials are becoming important in many areas of technological application. In addition to the static load, such structures may be stressed with short-term dynamic loads or even dynamic impact loads during their lifespan. Dynamic effects can be significant especially for thin-walled shell structures and barrier constructions. Impact loading of construction components produces a complex process, where both the characteristics of the design itself and the material parameters influence the resultant behavior. It is clear that reinforced concrete with fibers has a positive impact on increasing the resistance to impact loads. Results of impact load tests carried out on drop-weight test machine are presented in this paper. The results are supplemented by static modulus of elasticity.
Pore Structure Analysis of Portland Cement and Blended Portland Cements Cured under Hydrothermal Conditions
Authors: Ifka Tomáš , Palou Martin , Kuliffayova Marta , Boháč Martin , Frajkorová Františka , Bagel Lubomir
Published: August 2014

The pore structure of Portland cement pastes cured under different hydrothermal regimes was analyzed. Pore size distribution (PSD), hydraulic permeability coefficient (HK) and porosity (P) were found depending on temperature and steam pressure. With increasing hydrothermal characteristics, the pore structures degraded causing the depletion in compressive strength. Then, blast furnace slag (BFS) and silica fume (SF) were added to PC and cured under similar conditions. It was found that the pore structure was greatly improved. The effect of hydrothermal curing may be interpreted by the intensity and position of the peak, by the length and bimodal characteristic of PSD. The maximum concentration of pores of reference cement paste lies in the range 10 – 103 nm, and changes progressively to the size < 10 nm with increasing addition of BFS and SF. This behavior is attributed mainly to the presence of SF. Microstructure analysis shows hydrate products like needle CSH and CASH, which were stable under hydrothermal curing.
Monitoring of Reinforced Concrete Structure Corrosion by Using Impact-Echo Method
Authors: Šamárková Kristýna , Štefková Daniela , Chobola Zdeněk
Published: August 2014

This study deals with frequency inspection of response signal which was obtained from a reinforced concrete beam. Impact-Echo method was used for finding the dominant frequency which is the main criterion for condition assessment of reinforced concrete. The results of acoustic method were compared with measurements of electrical resistance of reinforcing steel by using the Thomson double bridge. The concrete beam with a steel rod diameter of 6 mm was tested. Tension pulse was produced in the centre of the concrete beam and detected in opposite position of the concrete beam.
Application Acoustic Emission Method and Impedance Spectroscopy for Monitoring Concrete During Hardening
Authors: Pazdera Lubos , Topolář Libor , Kořenská Marta , Smutny Jaroslav , Kusák Ivo , Lunak Miroslav
Published: August 2014

It is known that concrete is one of the most popular building materials nowadays. There are many traditional, mainly destructive methods for monitoring its properties during its lifetime. It is clear that its properties depend significantly on the composition of concrete mixture. Concrete lifetime depends mainly on curing during the first 7 days after making the mixture. The paper shows the possibilities of applying Acoustic Emission and Impedance Spectroscopy methods during the early age of concrete.
Properties of Materials from Activated Fly Ash from Fluidized Burning
Authors: Poláček Jaromír , Šulc Rostislav
Published: August 2014

This article deals with the basic properties of materials based on alkali-activated fly ash which contains a portion of fly ash produced during fluid burning. The primary task of our research was characterization of physical and chemical properties of each type of fly ash and fly ash mixture. The new materials composed of fly ash mixture and fly ash may have the similar mechanical and physical properties. The work focused on findingan appropriate technological procedure, the optimum composition of mixtures. Long-term stability was simulated by means of accelerated aging of these materials.
Experimental Testing of Layered UHPFRC Beams
Authors: Rydval Milan , Kolisko Jiří , Huňka Petr , Mandlík Tomáš
Published: August 2014

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) is fine-grained cement-based material characterized by high compressive strength (exceeding 150 MPa) and high modulus of rupture (over 15 MPa). The results of strengths depend on the size of the tested element, the loading rate and the boundary conditions during a testing. This type of material is used in a lot of countries (e.g. Germany, France, the USA, Japan, Austria, and the Netherlands) but it is not commonly used in the Czech Republic. The bridge over R10 road from Prague to Mlada Boleslav near Benatky nad Jizerou was the first structure where UHPFRC materials were used for lost shuttering slabs. Due to inhomogeneity of the steel fiber distribution the maximum attained force ranged between 9.6 kN and 25.7 kN for different lost shuttering slabs. The amount of steel fibers was very low at a tension zone at slabs with the lower load-bearing capacity. Steel fibers in these slabs were at the bottom of the formwork. The inhomogeneity of the steel fiber distribution was the foundation for producing of functionally layered beams with controlled inhomogeneity due to the mixtures with different fibers volumes. The results and behaviors of the layered beams and the homogeneous beams are presented in this paper.
Calcium Aluminate Cement and Porcelain
Authors: Sokolař Radomír , Vodová Lucie
Published: August 2014

Porcelain is a traditional ceramic material, which is manufactured for centuries from a mixture of kaolin - quartz - feldspar. Replacement of kaolin for calcium aluminate cement can be achieved primarily increases strength of fired body, reduces the coefficient of linear thermal expansion, increases the whiteness of the fired body and increases of sintering activity.
Influence of Storage Conditions on Quality of Fly Ashes
Authors: Kalousová Hana , Bartoníčková Eva , Opravil Tomáš
Published: August 2014

The presented paper deals with the issue of influence of storage conditions on the quality of conventional fly ashes which are produced by combustion of lignite. These ashes were stockpiled for long time. A borehole for sampling was made in the fly ash stock-pile. Total depth of the borehole was 20 m. Samples of fly ashes taken from every single meter were analyzed and next mechanical properties and the volume stability of materials containing these fly ashes were tested. The quality of fly ashes especially with respect to the possibility to use them as components of pastes, mortars and concretes as pozzolanic admixture or fine filler was evaluated.
Influence of Material Properties of Input Raw Materials on Microstructure of Aerated Concrete
Authors: Helanová Ester , Janovský Radek , Drochytka Rostislav
Published: August 2014

One of the basic conditions of production of high quality products from aerated concrete is selection of appropriate input raw materials. Their material properties have crucial influence on the whole process of production of the products from aerated concrete - from behavior of fresh mix of aerated concrete through setting to development of mineralogical phases during autoclaving. Properties of input materials, in particular their chemical composition has considerable impact on the final properties of the product made from aerated concrete. This paper summarizes current knowledge from the research of microstructure of fly ash aerated concrete depending on chemical composition of the raw materials in the mix.
The Effect of the Type of Reinforcement on the Mechanical Parameters of Concrete and on its Explosion Resistance
Authors: Drdlová Martina , Holešinský Radek , Řídký Radek , Křesťan Jan
Published: August 2014

The paper summarizes the up to now results of the development of special concrete intended for the explosion resistance applications, the emphasis is put also on minimal secondary fragments formation at the explosion. The fine-grained concrete matrix has been reinforced by various types of dispersed fibers (metallic, mineral and polymer) of different sizes and by their combination, while the same volume content of fibres has been kept. The concrete prism samples have been subjected to the determination of mechanical parameters (compressive and flexural strength, modulus of elasticity). The concrete test elements of the same sizes as commercial products have been made and their explosion resistance was tested. The material characteristics and explosion test data have been used for modeling the adequate wall thickness of the concrete element which should resist the explosion defined by type, size, weight and placement of the blast. In the next step the test elements has been reinforced by additional outer layer of non-metallic tissue and subjected to explosion tests.
The Environmental and Energy Potential of Incinerating Various Biomass Mixtures
Authors: Hroncová Emília , Ladomerský Juraj
Published: August 2014

In recent years, research has shown the advisability of seeking new types of biofuel. It has been shown that apart from one-component fuel, it is also advisable to use mixtures composed of basic raw materials. These mixtures may have a favourable effect upon the overall recovery of such fuels. This paper focuses upon options for the energy use of various mixtures of biomass waste. Biomass waste originates from primary agricultural production and countryside maintenance. This mainly consists of plant residues, i.e. straw and hay. Pellets were made using the given biomass. The pellets were prepared by mixing plant residues with spruce shavings as well as from pure materials, i.e. wheat straw, hay and sawdust. Individual types of biomass were mixed in various ratios: 50% wheat straw + 50% hay, 50% wheat straw + 50% sawdust, 50% hay + 50% sawdust, 33% wheat straw + 33% hay + 33% sawdust. The following basic parameters of the prepared samples were monitored: humidity, calorific value and ash content. These parameters influence the environmental as well as economic aspects of options for using these plant residues as fuel. It was discovered during the tests that the highest calorific value was achieved using a sample of biomass prepared by mixing 50% straw and 50% hay. The highest humidity was found in a sample of sawdust and the highest ash content in a sample prepared by mixing 50% straw and 50% hay.
Safety Aspects of the Renewable Sources of Materials and Energy – Biomass Processing
Authors: Balážiková Michaela , Tomašková Marianna
Published: August 2014

The anticipated increase in the demand for wooden biomass for the production of pellets requires focusing attention on the issue of safety and health protection at work as well as application of modern machinery to minimize the risk of injury or damage to health. Biomass gasification is a promising technology, which can contribute to develop future energy systems which are efficient, safe in design and operation as well as environmental friendly in order to increase the share of renewable energy for heating, electricity, transport fuels and higher applications. Biomass gasification is ready for commerce but today large-scale introduction is hampered by various reasons. Health and Safety issues are recognized as a major barrier in the deployment of this technology.
Activation Energy of Teak and Oak Wood Spontaneous Ignition
Authors: Martinka Jozef , Chrebet Tomáš
Published: August 2014

This article deals with evaluation of the spontaneous-ignition activation energy of the Teak wood (Tectona grandis L.f.) and the Oak wood (Quercus robur L.). Spontaneous-ignition activation energy was calculated from dependence of ignition time to inverse value of thermodynamic temperature. This dependence was measured in the hot-air (Setchkin) furnace according to ISO 871:2006 standard by modification of the test procedure. The modifications of test procedure lay in measurement of the time to ignition of sample loaded by various temperatures (at spontaneous ignition temperature and at temperatures above this value). The mass of investigated samples was (3 ± 0.05) g and its moisture contents was 0 wt %. The dimensions of sample was (20 x 20) mm, the third dimension was adjust to achieve required mass of sample. The activation energy of spontaneous-ignition for Teak wood was 78.23 kJ.mol-1 and for Oak wood was 59.24 kJ.mol-1. The spontaneous-ignition temperature for Teak wood was 460 °C and for Oak wood was 450 °C. Thus despite slight difference between spontaneous-ignition temperatures of investigated materials the difference between activation energy of spontaneous-ignition is significant.
Effects of Retardants on the Ignition of Wood Materials
Authors: Draxlerová Mária , Harangozó Jozef , Balog Karol
Published: August 2014

This scientific article deals with the impact of heat flow on the flammability of solids with the application of fire retardants, which can slow or limit the burning of solids. During the experiment spruce and beech samples were selected. The source of the heat flow was a radiation panel with a capacity of 15 kW. The time until the ignition of individual samples was monitored.
Evaluation of the Gross and Net Calorific Value of the Selected Wood Species
Authors: Orémusová Emília , Tereňová Ludmila , Réh Roman
Published: August 2014

The article deals with the important characteristics of the fuel energy parameters as the heat of combustion and ash contents of selected species of hardwoods and softwoods. In the research there were used the following wood of trees: pine, spruce, beech and maple, with calorific values ascertained separately for wood, bark, leaves and needles. Gross calorific value (another equivalent term is heat of combustion) was determined and calculated according to ISO 1928 “Heat of combustion of solid fuels”. Because the net calorific value of fuel significantly decreases with the moisture, the net calorific value of samples was determined not only in the absolutely dry state, but also at different percentage of moisture. The highest values of heat of combustion have been shown needles of pine wood (21.32 MJ.kg-1), bark of spruce wood (21.21 MJ.kg-1), leaves of beech wood (20.44 MJ.kg-1) and inner wood of spruce tree (20,54 MJ.kg-1). As other important energetic characteristic of wood a contents of ash have been measured and evaluated. Ash values from specimens of tested tree species were in the range from 0.78 up to 5 %. The average value of the residuum is 2.07 %. The lowest value was found for the field maple wood 0.78 % and the highest one for the bark of the same maple 5 %. The highest ash values were measured in most cases for needles and leaves; only for maple it was for the bark. On the other side, the lowest residuals were found for the wood itself.
Forest Fires Extinguishing Using Suitable Fire-Fighting Equipment
Authors: Monosi Mikuláš
Published: August 2014

The paper deals with the problem of forest fire occurrence in the Slovak Republic. It in more detail describes the number of fires in natural environment, analyses the problem of suitable fire equipment selection to fight the forest fires in meaning of the legislation standards. It also describes the optimization model to select the suitable fire equipment, based on the parameters of the natural environment and operational conditions of available fire equipment.
Ecological Energy Systems Suitable for Polymetallic Nodules Mining from the Seabed
Authors: Domaracká Lucia , Végsöová Oľga
Published: August 2014

The submitted article is dealing with very delicate problem, how to supply with energy the whole system for polymetallic nodules mining. The whole mining system requires almost 6 megawatts. The environmental impact should be enormous at every level of the seabed mining, so it has to be taken in consider choosing the best way how to supply the mining system with energy. The article deals with renewable energy and its possible utilization at the sea.
The Mass Loss Rate of a Candle during Burning
Authors: Kral Ján
Published: August 2014

The presented article deals with setting the effect of paraffin candles and thickness of their wick on the speed of candle weight loss. The paraffin candles with gauge of 1.8 to 6.8 cm and wick thickness of 1.5 to 3 mm were subjected to the test. The test procedure was based on setting the tested candles on a digital scales with resolution of 0,001 g in a digestor during time period of 20 minutes and the subsequent recording of the weight in time interval 5 s during 20 minutes. The obtained results show that the rate of burning candles increases with increasing the thickness and the diameter of the wick. Maximum rate of weight loss (0.1305 g/min) was achieved by the candle with diameter of 6.8 cm and thickness of 3 mm wick. Minimum rate of weight loss (0085 g / min) reached a candle with a diameter of 1.8 cm and a thickness of 1.5 mm wick.
Hearing Protection against Noise of Fire Trucks in Forest Fires
Authors: Mračková Eva
Published: August 2014

The Paper is focused on measuring of noise in fire tracks. The object is to find out whether it is exceeded the limit value of noise exposure at selected fire rescue trucks inside the cabin when the engine and siren are switched on, as well as outdoor environment. Measured results were evaluated according to applicable regulations and standards.