bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Improved AHP Evaluation in Supporting the Right to Determine the Weight of Deep Foundation
Authors: Jiang Hong Yan , Yu Gang Gang
Published: April 2014

The traditional AHP in the judgment matrix is established by using 1-9 scale, this scale has transfer difference, consistency of judgment matrix and thinking is not equivalent shortcomings. The improved AHP scaling theory is used in deep foundation pit support index weight determination, the selection of foundation pit supporting is more comprehensive scientific reasonable accurate.
Study on Coal Seam Mining Face Floor Failure under Imbalance High Water Pressure
Authors: Song Chun Jie , Fan Cheng , Song Li
Published: April 2014

According to the seam floor aquifer inhomogeneity,in order to analysis the coal deformation and failure law in pressurized water ,this paper established mechanical model of nonuniform pressure and fluidstructure interaction models,using numerical simulation software FLAC3D analysis fluidstructure interaction water inrush regularity .Analyzing the extent of damage from the coal seam floor, the stress and displacement when working face promote different distances, this paper carried out the basic rules of mining face water inrush. This study shows that by monitoring the position of bottom water inrush occurs easily, analyzing the influence of pore pressure by the mining ,it can be accurately analysis the risk of water inrush and play an important role in guiding prevention and control of water inrush.
Testing and Numerical Simulation Research on Shear Band of Soil
Authors: Hou Shi Wei , Qu Jin Hong , Du Xiu Li
Published: April 2014

The triaxial equipment of GDS with digital image processing technique is used in drained test of sand. The result shows that the end restraint and initial defect have significant effect on mechanical properties of sand sample. End restraint and initial defect of sample both can cause inhomogeneous deformation, then form macroscopic shear band in soil testing and numerical simulation. Shape multiformity and formation mechanism of shear band in normal consolidated soil is analyzed based on Modified Cam-Clay Model under plane strain condition. The result shows that end restraint and initial defect can induce and control the formation and shape of shear band. The impaction of different boundaries and initial defect setting are analyzed.
The Application of Stepwise-Discriminant-Analysis Oriented FCM Method in Debris Flow Classification
Authors: Shangguan Yun Long , Wang Qing , Chen Jian Ping , He Long Xiang , Yan Ji Yu
Published: April 2014

In recent years, the increasing Debris flow has been drawing the geologists' attention for its massive destructive force. At present, the research on the debris flow are mainly based on comprehensive multi-factors evaluation or singlue factor qualitative anlalysis. However, all factors have the impact on the debris flow. At present, the research on the factors that foundamentally affecting the debris flow or its character is quite few. This paper use the method of stepwise discriminant analysis to minimize the correlation and repeatability between factors to ensure the selected factor can be fully represent the character of debris flow. In addition, classification is an important way to illustrate general picture of the debris flow. This paper classified the selected 6 key factors by method of FCM (Fussy C Means) to achieve the transition and evolution from general geological classification to the accurate quantitative analysis. The result of such classification will benefit the debris flow cognition and disaster prevention measures.
The Strength Calculation Method of Foundation Treated with Sand Well
Authors: Zhang Yu Cheng , Hu Hai Ying , Huang Zhong Ming
Published: April 2014

Due to the characteristics of the physical mechanical properties of soft ground, reasonable foundation treatments are usually necessary before it meets the need of foundation deformation and load requirements. How to choose a reasonable foundation treatment method which has obvious virtues of economical expenditure and shorter construction period is an urgent problem emerging in engineering construction in the Pearl River Delta. While drainage sand well is used widely in soft soil foundation treatment in the Pearl River Delta. In this paper, a simplified calculation method is proposed to calculate the strength of soft soil foundation treated by sand well after drainage consolidation.
The Study of Jinnan Loess Collapsible and Depth
Authors: Yuan Kang Feng , Zhao Jin Bin
Published: April 2014

At present, there are not enough research for the initial collapse pressure and collapsible coefficient of the loess in the country; There are tests for the Jinnan collapsible loess, to study the collapsible coefficient and the initial collapse pressure changes with the depth. The results showed that: When the vertical pressure is 200 kPa , the collapsible coefficient is the largest. The collapsible coefficient decreases with the depth increase. The initial collapse pressure increases with the depth increase.
Study on the Prevention Measures and Causes of Cracks in Arch Crests of Galleries in High Concrete Dams
Authors: Chen Pei Pei , Zhang Guo Xin
Published: April 2014

More and more high dams with huge reservoirs have been built in China in recent years. A lot of research work on the causes of cracking in galleries of low concrete dams has been carried out at present, while studies on that of high concrete dams are less with the lack of systematic cognition. Based on that, the research on high concrete dams is conducted in this paper, using the method of finite element simulation. It is proven that self-weight action has more influence on the stress of arch crests of galleries existing in high concrete dams, especially the galleries whose overlying concrete height is relatively high. And surface cracks tend to appear in arch crests of these galleries under gravity. In the end, measures for improvement of the stress of arch crest are put forward, of which the effect of enlarging reinforcement is relatively obvious.
Analysis of the Influence of Water Content on Shanxi Loess CBR and Rebound Module
Authors: Wu Xi Rong , Zhu Li Li
Published: April 2014

Selection of five typical loess in Shanxi Province, the paper adopt the indoor test methods to prepares the different compaction and different moisture content specimens which were used to test CBR value and rebound module, analyzes the impact of compactness and moisture content on the CBR value and resilient modulus and establishes the relationship of CBR and moisture content. The result shows that the level of moisture content has great impact on CBR value and rebound module. The CBR value is maximal under optimum moisture content and maximum degree of compaction condition. The times of compaction have little effect on the improvement of CBR with increasing water content. The relationship of the soaking CBR,resilient modulus and the moisture content shows a certain regularity.Key words: Loess filler;the CBR;resilient modulus;compactness;moisture content;relationship
Experimental Research of Matrix Suction of the Unsaturated Red Clay
Authors: Zhao Wen Feng , Li Long , Xiao Yu Hang
Published: April 2014

Matric suction has great impact on the strength of soil. Some physico-mechanical indexes, such as the water content, dry density of soil, have close relationship with the matric suction. The experiments were conducted in the laboratory to study the relationship between the matric suction, the water content and dry density of unsaturated red clay. The filter paper method was used to get the soil-water characteristic curve of the unsaturated red clay. The results show that: water content has great impact on matrix suction. The soil-water characteristic curve can be divided into three stages. In low water content area, matrix suction decreases rapidly with the increase of water content.Then, the rate of change slows down after the inflection point. Matrix suction increases obviously with the increase of dry density under the condition of low water content, but the impact disappears under high water content. So the matrix suction is affected by dry density and water content.
Ground Treatment and its Application in Shallow Subway Tunnel Crossing Urban River by Shield Tunneling Method
Authors: Zhou Xiao Jun
Published: April 2014

On the basis of the geological and environmental conditions of surrounding rock around a shallow subway tunnel used to cross a river in Chengdu subway line one, the ground treatment technique such as uplift piles, cast-in-place reinforced concrete slabs and site grouting have been summarized in the paper. The riverbed above shallow shield tunnel is reinforced with covering slabs and uplift piles; meanwhile, the surrounding rock is reinforced with cement and sodium silicate grout by high pressure grouting method conducted inside the tunnel. The practice of the scenario presented in the paper turns out to be a great success and shows that the treatment technique can be used to guide the design and construction of ground reinforcement for shallow tunnel used to cross urban rivers in subway lines by shield tunneling method under similar conditions.
Evaluation of Snow Load Using a Wind Tunnel on the Arched House
Authors: Paek Sun Young , You Jang Youl , You Ki Pyo , Kim Young Moon
Published: April 2014

A damage occurrence of single-span type greenhouse by heavy snowfall in Korea, M shape collapse where excessive snow load of the roof occurs frequently regardless of the area damaging all the roof rafters. Therefore, in this paper, the snowdrift pattern of the arched house by shape using snow wind tunnel simulation is necessary. Experimental results indicated that the snowfalls on the roof of the arched house occur variously depending on the shape and location. As a result of estimating the load standard by roof slope angle and the values of snow loads using wind tunnel experiment, roof slopes showed 30% in 0°-15°and 80% in 45°-70° respectively, which were significant percentages in the snowdrift experiment.
Study on Structural Design and Driving Process of Subway Station Passageway Crossing Urban Trunk Road by Tunneling Method
Authors: Zhou Xiao Jun
Published: April 2014

On the basis of unfavorable geology of a passageway in subway station to cross urban trunk road with heavy traffic flow in Chengdu city, the comparison of two different driving methods for the underground passageway with three arches and two pillars is carried out in the paper. The result shows that both center drift-pillar method and partial bench-cut method can be used to build the passageway in the subway station. But the latter is superior to the former in reducing construction cost, risk and timescale. While the former is more efficient in controlling ground subsidence. The tubular roof protection is also designed to reinforce the shear strength of soil above the crown of the passageway before excavating the poor surrounding soil. The inventive driving procedure of partial bench-cut method presented in the paper can be utilized to guide the rational design and economical construction of shallow passageway for subway station to cross urban trunk road in weak geological strata.
The Analysis of Stratum Settlement for a Large Diameter Slurry Shield Obliquely Under-Passing Embankment of the Yangtze River
Authors: Jiang Zhou Yun , Yu Jie
Published: April 2014

Displacement caused by tunnel excavation soil may cause the deformation of the buildings or structures nearby and even cause disaster. On the background of a large diameter slurry shield obliquely Under-passing embankment of The Yangtze River. First of all, three dimensional finite element method is used to make a dynamic analysis of the embankment settlement. And the result is compared with the measured values, the accuracy of the finite element method was verified. Then, the stratum settlement of embankment is analyzed under different cross Angle and depth of tunnel. Some useful conclusions are drawn, which can provide some useful reference for similar engineering of tunnel under-passing embankment.
Analysis of the Potential of Seismic Stability for the Southern Region of Tangshan Based on ArcGIS
Authors: Li Cheng Cheng , Yuan Xiao Ming
Published: April 2014

To assess the potential of seismic stability for the southern region of Tangshan city, five factors are considered, including fault zones, engineering geological condition, hydrogeology condition, dynamic coefficient and site category. In this paper, the process and digitalization and visualization technology of evaluation method for site seismic stability is proposed based on ArcGIS. The overlay method is automatic realized and the seismic stability potential diagram of Tangshan and its southern region is given, which overcomes the drawback that can't automatic classification of other GIS instruments, then time is greatly saved and the efficiency is improved.
Evaluation of the Fire Resistance of H-Section Made of High Strength Structural Steels with a Difference of Length
Authors: Kwon In Kyu
Published: April 2014

High-rise building is one of solution for lack of houses and offices in downtown. And high-rise buildings can be built by application of high strength materials such as structural steels and concrete. Particularly, high strength structural steels have much efficient properties in not only design phase but construction one. Therefore, the use of the high strength structural steels has been increased every year. However, the H-section made of the high strength structural steels can be designed and constructed with longer height than that was evaluated for fire resistance by fire test to satisfy the fire regulation. In this study, to suggest an exact fire performance at high temperature of H-section made of high strength structural steels, a fire engineering technique was used. The derived facts showed that SM 570 revealed better structural stability at high temperature and as longer length of H-section was used, the more fire protection materials requited.
Study on Resilience Model of High-Strength Concrete Frame Columns
Authors: Zhang Guo Jun , Lu Xi Lin , Liu Bo Quan
Published: April 2014

Based on the horizontaldisplacements and loads of column at top end deduced according to sectionalbalanceable conditions at yield of high-strength frame columns, the lateralmaximum loads of column at top end calculated according to the Chinese currentconcrete code and involved regressive formulas, the resilience model ofhigh-strength concrete frame columns were established. The main results show:the resilience models of high-strength concrete frame columns proposed in thispaper consider influenced multi-facts and conveniently applied to engineering.
The Improvement Ways to Equivalent Linearization Method Based on the Difference between Results of Two Programs in Moderate Weak Site
Authors: Yu Xiao Bo , Sun Rui , Meng Shang Jiu
Published: April 2014

Equivalent linearization method is widely used in seismic response analysis. For Chinese engineers and researchers, LSSRLI-1 and SHAKE2000 are good choices for seismic safety evaluation. There is large difference between the results of these two programs in moderate weak sites, which directs ways to improve them. The average spectrum ratio increases with response spectrum peak value of inputting wave moving from long period to short period. The shear strain obtained by the programs exceeds shear capacity, which is impractical. In the type III site, the weak foundation exacerbates the error. In the way to improvement, frequency components of inputting wave should be taken into account, and a further study on computation method of strain should be launched. For security purposes, seismic safety evaluation for major projects needs multiple method for reliability, especially constructions sensitive to shear strain.
The Stiffness Change and Dynamic Characteristics of the RC Frame Weak Layer under Strong Earthquakes
Authors: Jia Hao Hua , Wei De Min
Published: April 2014

In China Wenchuan earthquake, the main characteristic of reinforced concrete frame structure is the weak layer yielding or collapse. Through the analysis of the stiffness change of the reinforced concrete frame weak layer during the whole process form the elasticity, yielding till collapse, the dynamic characteristics of reinforced concrete frame weak layer in the yielding and collapse processes were discussed. The lateral stiffness of the frame weak layer includes two parts: the lateral stiffness and the equivalent negative stiffness of column under the load action. It is shown that when the value of former decrease to the latter, the weak layer is in a collapse critical status. The frame weaker experiences form steady periodic vibration to variable periodic vibration then aperiodic motion. Some obvious chaos characteristics exist in the aperiodic motion in the plastic stage. It deserves further study to avoid weak layer collapse caused by the chaos motion.
Nonlinear Seismic Responses Analysis of Jinwan Square No.9 Building
Authors: Qi Lin , Huang Zhao Wei , Hu Xue Ying
Published: April 2014

Nonlinear time history seismic analysis of Jinwan square No. 9 building under strong earthquake is made. Three dimension structural nonlinear analysis and performance estimate programme Perform-3D is used to establish the calculatrion model. FEMA beam, shear strength section are used to set up the frame beam element modal; Moment plastic hinge, shear plastic hinge and elastic beam section are used to set up the link beam element modal; FEAM column and shear strength section are used to set up the column element modal; fiber wall element is used to model the sheae wall. Performances of the structure under strong earthquake are analysed. Numerical calculation results indicate that the structure design satisfies the preestablished performance targets.
Analyzing of Alternative Raw Materials for Production of Cement-Bonded Particle Boards
Authors: Melichar Tomáš , Helanová Ester , Bydžovský Jiří
Published: April 2014

The paper presents the results of research aimed at modifying the composition of the cement-bonded particleboards. These materials can be used as a suitable finish surface treatment among others for renovations of not only older buildings. Specifically, a problem of analyzing of selected and actually produced alternative raw materials in connection with previous results and findings. The effect of pretreatment with suitable grinding equipment was tested. Furthermore, it was the use of thermal methods for the quantification of the constituents of the analyzed material. In terms of subsequent modification of the composition of cement-bonded particleboards outputs can be found the outputs stated in the article as essential and beneficial for continuing research. The presented results also provide details of earlier findings made in this area.
Non-Destructive Methods for the Localization of Woodworms via Acoustic Analysis
Authors: Fiala P. , Friedl M. , Šmíra Pavel , Nasswettrová Andrea
Published: April 2014

The problem of finding a suitable diagnostic procedure for the examination of structural elements has been closely analyzed in recent years. In this connection, the main material of interest is wood as a type of heterogeneous matter, and the diagnostic procedure is directed towards enabling prospective industrial application. A new diagnostic method based on X-ray imaging and acoustic electromagnetic waves has been proposed and tested. The X-ray technique utilizes the reduction of the imaging information into 2D planar projection; it allows us to represent clearly the rate of material damage through displaying the weighted damage rate.
Evolution of Reconstruction of Plecnik Footbridge at Prague Castle
Authors: Vacek Vítězslav , Kolisko Jiří , Hrabánek Milan
Published: April 2014

The sample of not sustainable way of reconstruction of small but important and significant structure of Plecnik ́s foot bridge located at Prague Castle area is discussed at this contribution. The structure was strongly impaired 10 years after complex reconstruction. This damage and degradation was caused mainly due to malfunctioning of new waterproofing and frozen water in the drainage system of the bridge deck.
Options of Assessment of Absorption Capacity of Noise Barrier
Authors: Vacek Vítězslav , Holub Jan
Published: April 2014

The contribution deals with the possibilities of measuring the sound absorption coefficient of concrete panels. On the example of the modified concrete shows one of the possible methods that could be used to check for changes in the case of acoustic properties of restoration of the damaged panels. The issue of evaluation of the sound absorption coefficient is quite complex and difficult in the interpretation of the results, primarily due to the impact of the size of the tested element and parasitic interference in the surrounding environment.
Use of Textile Reinforced Concrete – Especially for Facade Panels
Authors: Novotná Magdaléna , Kostelecká Michaela , Hodková Julie , Vokáč Miroslav
Published: April 2014

In recent years, textile reinforced concrete (TRC) is at the beginning of industrial production mainly in Germany and relates especially to facade panels and concrete footbridges. The subtle panels with a minimum thickness of coverage layer can be designed due to the textile reinforcement, which is resistant to corrosion. Furthermore, a long durability is expected in case of these structures. The textile reinforcement with the fine-grained ultra-high performance concrete (UHPC) enables to produce concrete elements with a minimum thickness. Therefore, the concrete element with up to 70 % lower weight compared to element with conventional reinforcement can be produced and significant environmental savings can be achieved (reducing the consumption of non-renewable raw materials, transport energy, reduced dead load acting on the supporting structure, etc.).
Effect of Artificial Lightweight Aggregate on Resistance of Polymer Cement Mortars to Extreme Temperatures
Authors: Keprdová Šárka , Melichar Tomáš , Černý Vit
Published: April 2014

This paper presents the results of research focused on the modification of composition of the polymer-cement mortars. The use of these materials is quite wide. The greatest use can be found in the production of reinforced concrete repair materials. Specifically, the article analyzes problems of lightweight aggregate effect on the resistance of polymer-cement mortars to extremely high temperatures. The link is particularly evident with the risk of fire. Attention was given to the two different types of aggregates - from primary raw materials (Liapor) and alternative sources of raw materials (fly ash aggloporite). The study was carried out by the laboratory analyzing the basic material characteristics of prepared samples which were exposed to temperatures up to 1200 ° C.
Introduction to Problems of Candle Combustion in Buildings
Authors: Souček Jiří
Published: April 2014

From the earliest times of human history are used portable light sources. First advanced devices were torches and candles, and then human population started using kerosene lamps and other more sophisticated portable light sources based on biology or electricity. Light source based on a chemical reaction has one common denominator and that is the release of fumes while fuel combustion. In these cases, it is the source of its own, which is referred to such bodies or substances in which structure is formed light. Nowadays, historically valuable buildings more often server different purpose than they were originally built. This change in use can lead to a significant influence on historical building and its life span. One of the many factors negatively affecting the life of monuments are fumes from candle combustion. Massive use of candles releases toxic substances into the environment, which in high concentrations can affect human health and can also damage due to chemical reactions historically valuable monuments
Non-Destructive Prospection of Ancient Steam Bathes Covered with Tadelakt — First Preliminary Comparison of Hammam Kasbah des Caids of Tamnougalt and Hammam Kasbah of Taourirt, Morocco
Authors: Wolff Britta , Diederichs Ulrich , Ait el Caid Hassan
Published: April 2014

Nowadays the use of authentically, natural building materials for the preservation of monuments ends, where moisture and steam arises: in climatically challenging rooms like baths, kitchens, saunas, SPAs
By reference to two of the oldest steam bathes of Morocco we can try a more scientific view on the problem by focussing this kind of ancient architecture, which presents us the capability to protect earth building units by compressed, hydrophobized lime plasters.
Reported are the preliminary results achieved with non-destructive prospection of the old steam bathes by use of a 3D laser scanner with integrated colour camera.
Parameters of Cement Bonded Particle Boards Modified with Stone Wool Fibre
Authors: Vacula Miroslav , Klvač Martin , Mildner Robert , Keprdová Šárka
Published: April 2014

The contribution deals with possibilities of using waste from the production of stone wool for modification of the existing composition of cement boards . Waste - the fibres from the production of stone wool - was used as an alternative to the standardly used wooden filler (chips, sawdust). The waste was tested in laboratory and then added to the mixture for the production of cement-bonded particleboards as a substitute for wood filler. The physical and mechanical properties of laboratory-made boards with a modified recipe were monitored.
Connection of New Steel Rods to Original Wrought Iron Tongs Using a Clamp Joint during a Renovation of Teplá Monastery
Authors: Pospíšil Martin
Published: April 2014

Connection of new steel rods to original iron tongs in historic buildings is largely carried out by screwing. This solution requires drilling holes into the original iron element. Another solution - special welding - is also irreversible intervention into the original historic material. Clamp joints as a non-invasive solution were used to connect new steel rods to iron tongs originated from the late 17th Century in Teplá Monastery, Czech Republic.
Degradation of Laminated Glass as Result of Increased Temperature
Authors: Bittner Tomáš , Tej Petr , Bouška Petr , Vokáč Miroslav
Published: April 2014

The degradation of laminated glass as a result of increased temperature has become one of the important problem of reconstructions and designs of new glass structures, for instance high-rise buildings that are exposed to the impacts of an intensive heating caused e. g. by sunshine. The temperatures during heating can reach very high values, commonly from 60 to 70 °C. The effect of heating was simulated using the thermal chamber where the glass panes with the size of 120 x 1100 mm were heated. The deformation course under the increase of temperature was continually monitored by a measuring unit. In total six types of foils joining particular layers of glass were examined. In this paper the experimentally gained results are compared with a numeric computer analysis and the particular kinds of interlayers are evaluated using the loss of shear interaction.
Shear Tests of Composite Slabs, Experimental and Numerical Investigation
Authors: Holomek Josef , Bajer Miroslav , Barnat Jan , Vild Martin
Published: April 2014

Composite slab is being used for horizontal structures. The sheeting can serve as a permanent formwork and no additional reinforcement can be required. The slabs are then fast and easy assemble construction which can be effectively used in reconstructions. One of the meanings to assure composite action of composite steel-concrete slabs is prepressed embossments. Its main disadvantage is that the design of a new type of sheeting requires expensive and time consuming large-scale laboratory testing which hamper its widespread commercial usage. Small-scale shear tests present a less expensive alternative to the large-scale tests but its results cannot be simply used for the design of the whole slab. The results from small-scale tests with different options are compared in this paper. Also a possibility of contribution of FE simulation results to the small-scale tests usage is investigated.
Numerical Investigation of a Masonry Column Reinforced by the Helical Reinforcement
Authors: Jašek Marek , Mynarzova Lucie , Hurta Jan , Brozovsky Jiri
Published: April 2014

In recent years numerous advanced materials technologies have appeared in the market or have been developed for use in construction. In civil engineering there are also numerous fields of application for these materials, which can be used for construction of new buildings as well as for reparation and improvement of older structures.
In many cases the helical reinforcement is used for the improvement and rehabilitation of masonry structures. This type of reinforcement offers several advantages. It requires only minimal changes of the existing masonry elements and it introduces no visual changes of the rehabilitated structure. In the paper a numerical analysis and an assessment are presented of such a helical reinforcement for the improvement of axially loaded masonry columns.
Utilization of Wood Modification for the Purpose of Moisture Volume Changes Reduction
Authors: Murínová Tereza , Daňková Jana , Mec Pavel
Published: April 2014

Application of timber structures in civil engineering is completely traditional technology. On the other hand, the materials with better durability characteristics are preferred in present construction. Increased or fluctuating moisture of wood is a significant limiting factor of its life. Wood modification, which results in water intake reduction and also serves to maintain the low equilibrium moisture, may significantly improve the properties of wood, reduces the caused volumetric changes and extends its durability. Utilization of partial or total wood mineralization is just one of the material modification possibilities. This method seems to be promising due to so far gathered results, namely the anti swelling efficiency was greater than 65% for tested wooden species.
Selected Non-Destructive Methods Suitable for Evaluation of Roofing Slate
Authors: Vavro Martin , Souček Kamil , Daněk Tomáš , Staš Lubomír
Published: April 2014

Roofing slate is a traditional natural material for roofing and other construction applications in various types of buildings. The paper deals with both traditional methods of mineralogical-petrographic analysis as well as completely new methods (X-ray CT) rendering fast and reliable determination of qualitative parameters and potential slate durability in building constructions. A mutual combination of the methods represents a rapid, effective and modern alternative to lengthy laboratory tests to determine physical-mechanical properties of newly used roofing, especially in historical buildings.
The Influence of Mineralogical Composition Changes of Sandstone Cement on Physical-Mechanical Properties
Authors: Kovářová Kateřina , Pala Zdenek
Published: April 2014

The aim of the contribution is to present the results of research focused on cement mineralogical composition changes and their influence on physical-mechanical properties of sandstones. Three types of Czech sandstones were tested during this experiment Hořice, Kocběře and Božanov. The sandstone samples were treated in the climatic chamber in order to simulate weathering processes that are typical for winter period in Prague. The influence of road salts was also taken into consideration. For the purposes of mineralogical changes determination the sandstone cement was separated and subsequently analyzed using X-Ray diffraction a DTA/TG analysis. The physical-mechanical properties such as e.g. uniaxial compressive strength, water absorption and open porosity were determined before and after the climatic treatment to enable evaluation of the influence of weathering processes.
Analysis of Suitability of Mortar Used for Reconstruction
Authors: Pernicová Radka , Dobiáš Daniel
Published: April 2014

Assessment of suitability of mortar intended for reconstruction based on their characteristics, namely basic, hygric and mechanical parameters, chemical analysis and frost resistance, is presented in this paper. Properties of the load bearing structure as well as natural factors were also taken into account in assessing the suitability of the used mortars. Comparative measurements with original historic plaster are done as well. On the basis of the experiments performed, it can be concluded that not only mortar properties but also environment conditions and technology of application as well as load bearing structure characteristics have a great importance to the service life of the repaired parts of historical buildings.
Load-Bearing Capacity Determination of Historic Masonry Structures
Authors: Witzany Jiří , Čejka Tomáš , Zigler Radek
Published: April 2014

The experimental, in-situ and laboratory research has manifested a relatively large variance of the physical and mechanical characteristics of historical masonry found e.g. within a masonry wall, a massive masonry pillar etc. Artical presents the evaluation of the experimentally determined physical and mechanical characteristics of masonry members and the binder obtained by sampling specimens and by non-destructive measurements relies on the application of appropriate probabilistic methods.
Analysis of Relations for Determination of Parameters of Various Types of Concrete Based on Ultrasonic Pulse Method Measurement
Authors: Brožovský Jiří , Bydžovský Jiří
Published: April 2014

It is often necessary to determine strength of concrete (Normal-weight, High-performance and Light-Weight) in the structure. To determine strength, ultrasonic pulse method is used. However, the basic condition of its effective use is existence of relations between velocity of ultrasonic pulse propagation and strength. These relations are elaborated for normal weight concrete in great extent. However, for other types of concrete, relations for determination of strength on the basis of ultrasonic pulse velocity are stated in technical literature and their practical applicability could be questioned. The paper gives analysis of such relations from the point of view of practical applicability for determination of parameters of concrete built in a structure.
Fabrication on Hydrophobicity of the Etched Aluminium Alloy Surfaces
Authors: Li Jing , Cao Guo Hua , Zhang Xin Ming , Xu Cheng Yu , Li Qiang
Published: April 2014

Hydrophobic surfaces with contact angles greater than 90° and roll-off angles below 10° for water have been developed, based on low energy surfaces and rough texture on the micro-and nanometer scales. In this study, we fabricated a hydrophobic surface on a aluminum alloy substrate using the method of chemical etching without being modified by organic liquids such as surfactant-based solutions, alcohols, or alkanes. The measurement showed that the as-prepared surfaces possessed roughness on the micrometer scales by laser scanning confocal microscopy. The etched aluminum alloy surfaces had a maximum water contact angle of 120o by using a water contact angle measurement. The forming course of the aluminum alloy etched surfaces with pores was analyzed. The wettability of the etched aluminum alloy surfaces is reinforced by means of controlling the surface rough texture on the micrometer scales.
Dressing Field Control of Band Gap Reflection in a Homogeneous Atomic Medium
Authors: Li Li , Li Yuan Yuan
Published: April 2014

Dressing field control of band gap reflection is investigated in an inverse Y-type four-level atomic system. It is shown that when the dressing field is blocked, a band gap reflection with a maximum bandwidth and nearly ~90% reflectivity can be achieved for the detuning of the coupling field . When a weak dressing field is applied to the system (the intensity is much less than that of the coupling field), a narrowing top flat with ~86% reflectivity of the band gap reflection is observed in comparison with that in the first case. We also show that the band gap reflection can be dramatically suppressed due to the collapse of the stop band when a strong dressing field (the intensity is comparable with or larger than that of the coupling field) is employed. This control of photonic band gap reflection can be used in the applications of all-optical reflection mirrors and band optical filters.
Micrographs and Optical Properties of Al-Doped ZnO Thin Films Deposited by Radio Frequency Magnetron Sputtering
Authors: Li Yuan Yuan , Chen Zhen , Li Shu Li , Li Xi Long , Chang Geng Rong , Yan Jun Feng , Xu Ke Wei
Published: April 2014

The micrographs and optical properties of Al-doped ZnO (AZO) films deposited by radio frequency (RF) magnetron sputtering are presented in this paper. The AZO films termed as films I, II and III were sputtered on glass substrates heating at 300C, 400C and 500C, respectively. The micrographs, crystal structures and optical properties of AZO thin films were analyzed by using scanning electronic microscopy (SEM) images, X-ray diffraction (XRD) pattern, optical transmission and reflection spectra ranging from 350 to 1000 nm. As the substrate temperature increases to 500C, the film III exhibits a better flatness surface and a larger grain size of ~25nm with a stronger c-axis orientation. The film II has a high transmittance of greater than 92% in the visible light region. We also show that the films II and III have significant red-shift band gap ~3.00 and ~3.13eV, respectively, in comparison with that of the film I (3.31eV). This might be due to the increasing doped Al atoms which do not activate due to segregation at the grain boundaries.
Synthesis and Luminescence Properties of Pomponlike CaMoO4:Eu3+ Red Phosphors by Hydrothermal Method
Authors: Wang Xiao Feng , Wang Xia , Peng Gui Hua , Liang Zhen Hua , Wu Jing Long
Published: April 2014

The pomponlike CaMoO4:Eu3+ red phosphors were synthesized via a ethylene glycol (EG)-mediated hydrothermal method in the presence of urea at 140 °C for 1 h. The structure, morphology and luminescent property were characterized and investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL). The results show that the Eu3+-doped CaMoO4 micropompons were well-crystallized and assembled by nanosheets. The products display a strong red emission under near ultraviolet (UV).
Kinetics and Thermodynamics of Nanostructured Mg-Based Hydrogen Storage Materials Synthesized from Metal Nanoparticles
Authors: Shao Huai Yu , Li Xing Guo
Published: April 2014

Mg, Ni, Co, Cu and Fe nanoparticles with a particle size of 30-300 nm were synthesized by hydrogen plasma metal reaction method. Nanostructured Mg-based hydrogen storage materials (Mg-H, Mg-Ni-H, Mg-Co-H, Mg-Cu-H and Mg-Fe-H systems) were synthesized from these metal nanoparticles. In this work, the kinetic and thermodynamic properties of these nanostructured hydrogen storage materials were studied. It was found that nanostructure could significantly enhance the hydrogen absorption kinetics but the thermodynamics (desorption enthalpy and entropy) does not change with downsizing in the size range of 50 to 300 nm.
Degradation of Polymer Solar Cells Based on P3HT:PCBM System
Authors: Yu Huang Zhong
Published: April 2014

The degradation of the performance of the polymer solar cell based on the blend structures system of poly (3-hexylthiophene) (P3HT) and [6,-phenyl C61-butyric acid methyl ester (PCBM) is investigated. This study uses UV-vis absorption spectra, photoluminescence (PL) spectra, charge-transport dark J-V curve chart to explicate the reason for the degradation of the performance of P3HT:PCBM photovoltaic cells. Solar cell performance is degraded primarily through loss in short-circuit current density (Jsc) and fill factor (FF), the reduction in the Jsc and FF of the device is most likely to be due to the formation of the charge transfer complex, deep traps and destruction of the-conjugated system in the degraded P3HT:PCBM device. The exposure to oxygen and photo-oxidation lead to the emergence of these factors of the device performance degradation.
Keywords: Degradation; Performance; Solar cells; P3HT: PCBM
Combustion Characteristics of Composite Solid Propellants Containing Different Coated Aluminum Nanopowders
Authors: Yao Er Gang , Zhao Feng Qi , Xu Si Yu , Hu Rong Zu , Xu Hui Xiang , Hao Hai Xia
Published: April 2014

Aluminum nanopowders coated with oleic acid (nmAl+OA), perfluorotetradecanoic acid (nmAl+PA) and nickel acetylacetonate (nmAl+NA) were prepared. The combustion characteristics of hydroxyl terminated polybutadiene (HTPB) composite solid propellants containing different coated aluminum nanpowders were investigated. The result shows that the burning rate of the propellant sample containing nmAl+NA is the highest at different pressure, the maximum burning rate is up to 26.13 mm·s-1at 15 MPa. The burning rates of propellant samples containing nmAl+OA and nmAl+PA are almost the same at different pressures, and higher than the propellant samples containing untreated aluminum nanopowders only at the pressure range of 10 ~ 15 MPa. The flame brightness of different propellants under different pressure is not the same. The flame brightness is increased with the pressure increasing. The flame center zone brightness of the propellant containing nmAl+PA and nmAl+NA is brighter under 4 MPa, and the brightness of nmAl+NA is the brightest. The surface coating of aluminum nanopowder has little effect on the combustion flame temperature of solid propellant. The burning surface temperature increases with the pressure increasing.
First-Principles Study on Electronic and Optical Properties in Pr-Doped Anatase TiO2
Authors: Chen Hao , Yao Lan Fang , Yang Song Lin , Wang Ya Qin , Liang Xing , Huang Yan
Published: April 2014

The crystal structures, band structures, density of states, charge density, overlap population and optical properties of pure anatase TiO2 and Pr-doped anatase TiO2 were studied by using the plane-wave pseudopotential method based on the first-principles. After Pr doping, the valence band and the conduction band moved down and became dense, energy gap became narrow and a impurity band which consists of Pr 4f states appeared. And the dipole moment got improved, which is good for the separate of the electron-hole pairs. These effectively overcome two huge shortcomings of TiO2. Besides, Pr-doped anatase TiO2 produced more carriers which have good transport properties and the absorption spectra of Pr-O bond appear in the region that the wavelength is longer. The calculation results of optical properties show that the absorption edge occured red shift, which means the photocatalytic activity of anatase TiO2 got remarkable improved during visible-light region. This conforms to the previous analysis. So the photocatalytic activity of anatase TiO2 got remarkable improved after Pr doping.
Basicity and Crystal Phase of Mesoporous K2O-MgO/ZrO2-La2O3 Catalyst
Authors: Su Yu , Dong Guo Jun , Wang Cheng Yuan , Gao Jin Sheng , Ma Dong Sheng , Sun Zhi Zhong , Wang Peng
Published: April 2014

A new solid base, mesoporous K2O-MgO/ZrO2-La2O3, was prepared by hydrothermal and immersion process using a cationic surfactant C16H33(CH3)3NBr (CTAB) as template．The samples were characterized by N2 adsorption-desorption, X-ray diffraction(XRD), Raman spectroscope and CO2 temperature programmed desorption(CO2-TPD). XRD and Raman spectra indicated that the catalyst calcined at 600°C and 700 °C remained surface and bulk tetragonal phase and good mesoporous characteristics when the content of K2O is less than 0.5. While the monoclinic phase is appeared on catalyst surface when the content of K2O is more than 0.5 calcined at 700 °C. CO2-TPD proves that there are two adsorption states at high temperature corresponding to super alkaline sites of K2O and undecomposed KNO3. The catalyst with 0.4 mol ratio of K2O to ZrO2 calcined at 700 °C showed higher activity in the synthesis of di-2-ethylhexyl carbonate (DEHC) from dimethyl carbonate (DMC) and 2-ethylhexanol (EHOH).
Adsorption Behavior of Methylene Blue with Quaternary Ammonium Modified Chitosan Microspheres Resin
Authors: Guo Xing Mei , Chen Yu Fei , Zhang Qiu Yun , Zeng Li Xuan , Luo Ji Wen
Published: April 2014

Chitosan (CTS) is the partly deacetylated product of Chitin. It contains hydrogen bond and ionic bond, which can form a cage-like molecular network structure and thus it has a strong adsorption. According to the presence of hydroxyl and amino groups of the chitosan, through chemical modification, introduces different groups in repeating units become possible. In this article, different component of the rectorite (REC) were used to intercalate the chitosan in order to have the quaternary ammonium modification. Through this process we could obtain three kinds of chitosan/rectorite modified products. Besides, their structures were observed by using the X-ray diffraction (XRD) and Fourier transform infrared (FT-IR). This paper also explained the examination of the adsorption effect of three kinds of chitosan/ rectorite modified products to the methylene blue under different conditions. Whats more, it also discussed the main factors of this effect. The results showed that the three adsorption behavior of adsorbents can be described by using the Freundlich isotherm model. In three kinds of chitosan/ rectorite modified products, 4:1 CTS/REC-ETA demonstrated the best adsorption. Followed was the 2:1 CTS/REC-ETA. And the 8:1 CTS/REC-ETA was the weakest.
Mechanical Analysis and Identification Markings of Nanoparticle Distribution in Narrow Friction Zones
Authors: Sun Yan , Jiang Shao Yong , Zhou Wei , Lu Xian Cai
Published: April 2014

Through scanning electron microscope (SEM) observation on kinetic friction and static friction deformation, our data show that granular nanoparticles (commonly 60-80nm with diameter, d) are widespreadly distributions in narrow friction zones. Furthermore, the identification markings, such as nature, experiment and fabric orientation etc., usefully deal with the mechanical analysis,and the granular nanoparticle distributions in narrow friction zones could be subdivided into three kinds, i.e. simple shear, pure shear and rotational shear pattern. Additionally, note that under stress action physico-chemical phase changes might be respectively caused by internal cohesion and dynamic differentiation in the narrow friction zones. These analyses deduce that some few complex idea fields, including structural stress, physics and chemistry field, with spatial and temporal evolution exist in the narrow friction zones, moreover, they viably regulate the nanoparticle distribution.
Research on Heat Transfer Characteristics of Nano-Porous Silica Aerogel Material and its Application on Mars Surface Mission
Authors: Li Cong Hang , Jiang Shi Chen , Yao Zheng Ping , Sheng Song , Jiang Xin Jian , Zhou Bin , Du Ai
Published: April 2014

Based on the nanoporous network structure features of silica aerogel, the gas-solid coupled heat transfer model of silica aerogel is analyzed, and the calculation formulas of the gas-solid coupled, the gas thermal conductivity and the heat radiation within the aerogel are derived. The thermal conductivity of pure silica aerogel is calculated according to the derived heat transfer model and is also experimentally measured. Moreover, measurements on the thermal conductivities of silica aerogel composites with different densities at ambient conditions are performed. And finally, a novel design of silica aerogel based integrated structure and thermal insulation used for withstanding the harsh thermal environment on the Martin surface is presented.