bluuebunny/crossref_metadata_2025 huggingface dataset:
Solubility of Silicate from Sugar Cane Bagasse Ash in Alkaline Solution
Authors: Filho Primo Fernandes , Torres Sandro Marden , dos Anjos Romildo Henriques , Porto Andressa de Araújo Vieira , Barbosa Normando Perazzo
Published: July 2012

Sugar cane bagasse ash (SCBA) is a byproduct rich in silica, which it is present as of both crystalline and amorphous phases. This paper aims to evaluate the effect of grain size of residual SCBA particles on the solubility of silicate species in alkaline solutions that still needs examination. The influence of the amorphous character of the material was also investigated. Physical characterization was performed by the assessment of density and specific area of powder samples. Chemical and mineralogical characterizations were performed using different techniques including x-ray fluorescence, x-ray diffraction, infrared spectroscopy and scanning electron microscopy. The results indicate that the grinding process reduces the specific area of the particles of ash in a non linear fashion. The controlled burning of sugar cane bagasse increased the amorphous character of the ash. Nonetheless both factors affected the solubility of silicates, the degree of crystalinity appears to be the most important factor.
The State-of-the-Art Study on Long-Term Property of Recycled Aggregate Concrete
Authors: Xiao Jian Zhuang , Li Hong
Published: July 2012

This paper presents a review of the literature on long-term property of recycled aggregate concrete (RAC), which includes the long-term strength, shrinkage, creep, durability and fatigue behavior. Based on many investigations carried out at home and abroad, it can be apparently observed that there are many differences in long-term property between the normal concrete and the RAC. However the long-term property of RAC can be improved and guaranteed by selecting the recycled aggregates replacement percentage, optimizing the mix proportion design, appending fiber or to restrict the environmental conditions. This paper can be helpful to the comprehensive understanding and further research of recycled aggregate concrete.
Tests on Seismic Behaviors of Double Thin Skin Hybrid Walls Filled with Demolished Concrete Lumps
Authors: Wu Bo , Liu Chun Hui , Liu Qiong Xiang
Published: July 2012

Double thin skin hybrid walls filled with demolished concrete lumps (DCLs) are composed of two steel plate skin connected by rib plates, with the space between them filled with new concrete and demolished concrete lumps. In order to investigate the seismic behavior of double thin skin hybrid walls filled with DCLs, quasi-static tests of seven specimens were conducted. The parameters considered in the tests are: replacement ratio of DCLs, thickness of steel plate, axial load ratio, rib plate spacing and height-width ratio. Test results show that the seismic performances of double thin skin hybrid walls filled with DCLs are similar to the walls without DCLs, and the double thin skin hybrid walls filled with DCLs also exhibit acceptable ductility and energy dissipation ability.
Self-Compacting and Conventional Concrete with Mineral Waste: Fresh and Hardened State Properties
Authors: Bacarji Edgar , Marques V.C. , Toledo Filho Romildo Dias
Published: July 2012

Environmental preservation has been a theme debated in virtually every country in the world. Many measures are being taken to reduce the environmental impact due to unplanned development. Growing environmental restrictions to the exploitation of sand from riverbeds have resulted in a search for alternative materials to produce fine aggregates, particularly near to larger metropolitan areas. Artificial fine aggregates then appear as an attractive alternative to natural fine aggregates for concrete. This work is the final part of a study about the use of residues in concretes. Conventional Concrete (CC) and Self-compacting concrete (SCC) were developed replacing the natural sand by two types of mineral waste. Fresh state tests such as slump-flow, L-box, V-funnel test and column test were performed according to the Brazilian standards. The rheological characteristics (yield stress and plastic viscosity) of the SCC were determined using the BTRHEOM rheometer. At the hardened state, compressive strength was determined at 3, 14 and 28 days of age. Modulus of elasticity test was carried out at 28 days. Curves to mixture design were obtained to SCC and CC. For all mixtures and properties analyzed the good performance of the mineral waste used was proven. Finally and more important, it was demonstrated that it is possible to obtain structural self-compacting concrete, self-compacting concrete without structural purposes and conventional concrete by using mineral waste that works like fine aggregates and that on the other hand, without any destination, would cause serious environmental impacts.
Study for Utilization of Industrial Solid Waste, Generated by the Discharge of Casting Sand Agglomeration with Clay and of Blast Furnace Slag, in Concrete Composition
Authors: Mazariegos Pablos Javier , Sichieri Eduvaldo Paulo , de Andrade Zago Mário Sérgio
Published: July 2012

This research project accomplished a study on the technical feasibility of recycling industrial solid waste generated by the discharge of casting sand agglomeration with clay and blast furnace slag. For this, the plan proposed a methodology that initially establishes a process of solid waste encapsulation, by using solidification/stabilization technique on Portland cement matrices, in which the residuals act as small and large aggregates on the composition of concrete, and later it presents the possibility of using this concrete in the manufacture of concrete pieces (concrete blocks) for paving. The results obtained in this research achieved the objective set with great success, regarding the manufacturing of concrete pieces (blocks) for paving urban roads, whenever there is special vehicle traffic or demands capable of producing accentuated abrasion effects (surpassing the 50 MPa required by the regulation), which probes the technical practicability of using waste from sand casting agglomeration with clay and blast furnace slag used in this study, unlocking usage possibilities for construction.
Characterization Physics, Chemistry and Mineralogy of Waste from Kaolin and their Potential Pozzolanic to Alkali Activation
Authors: Ferreira Debora T.A. , Rocha Bruno Diniz , de Lira Elder Cunha , Gomes K.C. , Torres Sandro Marden , Barbosa Normando Perazzo
Published: July 2012

The University Federal of Paraíba has developed various researches to explore the potential for recycling of industrial waste of Paraíba. Among them, the potential of use in the waste generated by processing of kaolin, which is one of the activities of great economic importance to the State of Paraíba and municipalities producers, because it causes a great environmental impact due to lack of an established recycling process. The kaolin processing generates large amounts of waste, one of fractions, a sandy (called in this study of RGC) containing quartz, mica and calcite; and other clay (called in this study of RFC) containing higher amounts of kaolinite. This objective of study is the characterization physical, chemical and mineralogical of waste kaolin (RFC and RGC) in order to evaluate the potential use of these wastes in the alkaline activation using silicates sodium and potassium. The characterizations physics, chemistry and mineralogy were by XRF, XRD, Unit Mass, Specific Mass and Specific Area. With the objective of studying the potential of waste as a material pozzolanic, it was processing through grinding at 10.000, 20.000, 40.000, 60.000 and 80.000 rpm and with the purpose of evaluating the reactivity of materials, these wastes were calcined at 750°C/2h.The wastes RFC and RGC had different properties according to the processing. Thus, the waste RFChas the potential pozzolanic to use in alkaline activation.
Sanitary Ware Industry as an Aggregate to Produce Concrete and Mortar
Authors: Santos da Costa Juzélia , Martins Celso Aparecido , Baldo João Baptista
Published: July 2012

Chemical analysis of household waste from the sanitary ware industry is of fundamental importance in order to detect the presence of AAR (alkali-aggregate reaction), the same in field or laboratory. There are several test methods, these methods can detect pre-reactivity of aggregates compared to the sodium or potassium hydroxide present in hydrated cement paste. For the preparation of both the concrete and the mortar, from the recycled material, the aggregates were reduced until it had texture, close to the river sand and gravel. The analyses stayed in determining the potential of the alkali-aggregate reactivity. Thus the results of chemical and physical characterization of the material, indicated a willingness to be used as aggregate in mortar and concrete, due to the availability of waste, the good properties given and the gains in cost, beyond the environmental management, they promote the viability of the process of recycling of waste. 1
Structural Performance of Typical Beam-Column Joints in Yingxian Wood Pagoda - An Experimental Study
Authors: Chen Zhi Yong , Zhu En Chun , Pan Jing Long , Wu Guo Fang
Published: July 2012

Yingxian Wood Pagoda, built in 1056, is located in the town of Yingxian County, Shanxi Province, China. It is the oldest and highest standing ancient wood structure in China. The pagoda is octagon-shaped in plan, with a total height of 67.31m and a base diameter of 30.27m. It appears as a five-storeyed structure, but actually consists of nine storeys, with four shorter but stiffer storeys hidden between the five apparent storeys. Yingxian Wood Pagoda was built without any metal connectors like nail, screw, or bolt. Instead, Tenon-Mortise connections and Dou-Gong brackets were used to connect all posts and beams. Tenon-Mortise connections and Dou-Gong brackets have been playing a vital role for the pagoda to resist severe winds, earthquakes and some human-induced disasters for nearly a thousand years. To evaluate the safety of the pagoda, it is, therefore, useful to investigate the structural performance of the beam-column joints, most important for Yingxian Wood Pagoda to resist lateral load. In this study, two models of typical beam-column joints of the pagoda, MBCJ-I and MBCJ-II, were manufactured following a ratio of 3.4 to the prototype of the joints. Non-destructive cyclic loading test of the models under different vertical load and destructive cyclic test of the models under vertical load of 20kN were conducted. The hysteretic stiffness of MBCJ-I was lager than MBCJ-II, and increased linearly with vertical load N. The relationship between and N was obtained by regression of the test results using the least square method. The stiffness of model joint under vertical load was 70.6kN/mm. The failure modes, energy-dissipation performance, moment resistance and bending stiffness of both model joints were derived and discussed.
Variation of Tensile Strength Parallel to the Fiber of Bamboo Guadua Angustifolia Kunth in Function of Moisture Content
Authors: Gonzalez Mateo Gutierrez , Takeuchi Caori Patricia , Perozo Michel Córdoba
Published: July 2012

As other natural materials used in construction, Bamboo Guadua is affected by different factors that can modify its strength. One factor is the equilibrium moisture content, which is a physical property related to temperature and relative humidity of the area where the material is used. Several studies have shown that the material strength to different load requirements decreases as moisture content increases. Samples from three different regions of the Republic of Colombia (Coffee region, Valle del Cauca and Cundinamarca) were taken to study the variation of the tensile strength parallel to the fiber of bamboo Guadua Angustifolia Kunth in function of the moisture content. Ten culms were taken from each region and three sections from different parts of each culm (bottom, middle and top) were selected. At least seven samples of each section were extracted and tested (so the samples taken from the same piece of bamboo have similar characteristics). The natural moisture content of each sample was modified to determine the strength with different moisture content. The method to vary the moisture content used in the research guaranteed that each group of samples, with similar characteristics, had a moisture-controlled variation. Colombian Technical Standard NTC 5525 "Methods for testing the physical and mechanical properties of Guadua Angustifolia Kunth were followed to determine the tensile strength parallel to the fiber, as well as to determine the material moisture content. Tensile tests were performed after immersing the specimens in water for about 72 hours, when the material showed a pronounced variation in moisture content. Finding that tensile strength did not show an obvious decrease, the range of moisture content was reduced to less than 35%. In order to have all the information with samples with moisture content below of that percentage, the tests were carried out during a 3-hour range of time. Results showed that tensile strength of parallel fiber does not decrease as the moisture content of the material was increased in the moisture content range where the material is used as a structural element.
Sensor Network Design for Monitoring a Historic Swing Bridge
Authors: Monti Giorgio , Quaranta Giuseppe , Marano Giuseppe C.
Published: July 2012

Significant advances in the development and customization of various sophisticated technologies for structural monitoring have emerged during the last decade. Technologies for instrumentation, monitoring, load testing, non-destructive evaluation and/or characterization, three-dimensional finite element modeling and various types of analyses have now become available at a reasonable cost. Within this framework, the paper focuses the issues addressed in designing a sensors network for dynamic monitoring of a historic swing bridge in Taranto (Italy).
Carbon Footprint Analysis of Fibre Reinforced Polymer (FRP) Incorporated Pedestrian Bridges: A Case Study
Authors: Dai Jian Guo , Ueda Tamon
Published: July 2012

This paper presents a case study on the carbon footprint of a fibre reinforced polymer (FRP)-incorporated pedestrian bridge in comparison with a conventional prestressed concrete (PC) one. The CO2 emission is used as an index and calculated for both the material manufacturing and the construction processes. It is shown that using an FRP-incorporated pedestrian bridge to replace a conventional prestressed concrete (PC) bridge may reduce the CO2 emission by 18% and 70%, respectively, during the material manufacturing and construction periods, leading to a total reduction by about 26%. Such reduction is expected to be more significant if the life-cycle CO2 emission is accounted for, since the former type of bridge is free of corrosion and almost maintenance-free. Therefore, FRP-incorporated bridges may become a more competitive alternative to conventional reinforced concrete (RC) or PC ones with the increasing attention paid on the sustainability and environmental friendliness of construction industry by our society.
Inter-Story Capacity Spectrum for the Performance Based Seismic Design of Vertically Irregular RC Frame Structures II: Examples
Authors: Men Jin Jie , Shi Qing Xuan , Zhou Qi
Published: July 2012

The procedure to establish the inter-story capacity spectrum method is explained detailedly in partⅠ. In this part examples are presented to demonstrate the applicability and utility of the proposed method. It is shown that the vertically irregular RC frame structure can be directly designed with the methodology proposed in this work. It is also concluded that the new method can control the inter-story drift, the order and position of hinges of vertically irregular structures under different earthquake hazard level. Comparing to time history analysis method, it leans to cautious and is superior to direct displacement-based design (DDBD).
Design and Analysis of a Low Reflecting Concentrating Photovoltaic System
Authors: Wang Cheng Yao , Xu Yin , Zhang Yao Ming , Hua Yong Ming
Published: July 2012

In this paper, a concentrating photovoltaic (CPV) system with low ratio was successfully developed. In the design of CPV concentrator, a quasi-parabolic reflector was adopted. With the research of basic optical mechanisms, a mathematic model was built with the corresponding program. In addition, the width of light spot was analyzed with considering the symmetry of tracking errors and glass deformation in manufacture to identify reasonable values. The system was designed with a reflector of 10 flat mirrors, which has a geometrical concentration ratio of 8.18 and a flux concentration ratio of 5. The concentrating photovoltaic system was investigated experimentally under the various weather conditions. The output voltage profile and the output power of the flat PV system and the CPV system were presented to analyze the concentration ratio and the electric power. And the influence of soiling was also discussed. The results showed that the performance of tracking system was good in a clear day. Compared to the flat cell with the same system, the electric power was nearly increased by 4-5 times.
Study on Silo Pressure by Consider Storage Materials Density Changed along the Height
Authors: Yang Zhi Yong , Liu Shun Hu , Zhao Song , Hu Jun , Lu Zeng Chan
Published: July 2012

The difference existed between results of silos pressure calculation and the actual case, because the influence of density stratification was not taken into consideration. The aim of this paper was to obtain silo pressure calculating formula by consider of storage materials density stratified. To this end, we assume that the density was continuous changed along the height and differential equation of the storage materials pressure was established. By compared the results calculated from the equation with the results calculated from the code, it is found that the maximum pressure increased. The results showed density stratified is an import factor for silo pressure calculation and the equation obtained in this paper can provide references for the theory of silo pressure calculation.
Research on Numerical Simulation of Heliostat's Surface Wind Pressure
Authors: Wang Ying Ge , Li Zheng Nong
Published: July 2012

Heliostat is the major part of solar tower power station whose wind resistance is deemed significant in design. The CFD model of single heliostat under typical operating situation was founded by technology of numerical simulation based on standard k-ε model. This paper puts forward a mesh generation method applied to complex projects under different working conditions. The corresponding UDF program was framed & used to simulate proper wind field entry conditions. The wind pressure distributions variation rules at different wind direction & elevation angles got summarized. The drag coefficients, the lift coefficients, and the three-dimensional moment coefficients in wind power coordinate under different operating conditions were computed. The results agree well with experimental data though a little bigger error exists locally. Moreover, the flow field distribution hard to acquire in wind tunnel test was compensated to further explain origin of heliostats wind pressure distribution. The influencing factors and the variation rules discovered reveals that prediction by numerical simulation is practically satisfactory.
Study on Circular-Shaped Corrugated Steel Culvert Pipe for Highway Construction
Authors: Yue Feng , Zhao Jin Cheng , He Hao Ji , Wen Xue Jun
Published: July 2012

s. In this paper, we discuss the design and calculation methods of Circular-shaped Corrugated Steel Culvert Pipe (CCSCP) used in highway construction. With many advantages such as lightweight, environment friendly, cost-effective, rapid construction, etc., Corrugated Steel Culvert Pipe (CSCP) have been widely used in highway construction acting as the alternative of RC culvert in China in recent years. It will not crack under impact loads or vibrations due to the inherent strength of steel and the flexibility of the corrugated pipe section. The high ring compression of the pipe absorbs and transfers the load to the surrounding soil around the entire circumference. In this paper CCSCP is a kind of culvert which is fabricated to a circular shape by several pieces of corrugated steel plates jointed by high strength bolts. In this paper, a serial test is conducted on site in process of the fabricating of the CCSCP used in the construction of Shanghai North Outer Ring Line Highway in China. In addition, 3D FEM analysis is performed with the intent of contrasting with the result of the test. Some design methods are proposed in this paper, and they will be useful guidelines for safe design of CCSCP.
Analysis of Energy Consumption and Electricity Consumption Norm of Hotel Building in Changsha, China
Authors: Jiang Yun Sheng , Li Nian Ping , Wei Xiao Qing , Huang Qing
Published: July 2012

The purpose of this study is to discuss the use of energy in hotel building in Hunan province, P. R. China, and to explore the application of building energy conservation. 25 hotel buildings were selected and the investigations of energy consumption data was carried through in Changsha of Hunan province .The building comprehensive consumption of energy and electricity were got from the energy consumption computing method of public buildings. It can be got these indexes of unit energy consumption electricity consumption and so on through unit conversion. According to the current situation of building energy consumption and the related standings of Changsha, such buildings whose norm index range of energy and electricity can be obtained. Conclusion are as follows: It provide guiding significance for the energy-saving prediction which entire building and all of its system .This paper also provides some useful measures which about the applied promotion of related energy-saving technology in such buildings of the region.
Study on Mechanical Properties of Cavity Heat Insulation Walls Out-Of-Plane Loaded
Authors: Yang Chun Xia , Shen Ji Mei , Yang Wei Jun , Zhou Sai Jiang , Wu Ya Ying
Published: July 2012

The cavity heat insulation walls as a major form of multiple thermal insulation walls is the development of the energy-efficiency building materials. Attention is taken to describe the mechanics properties of cavity walls under out-of-plane load. In this paper, Mechanical model is developed for masonry walls out-of-plane loaded, and the analytical expressions about the internal force and deflection are abtained using the orthotropic theory. Limit deflection of interior walls under vertical and horizontal loads is calculated by mathematical software (MATLAB) and is simulated based on finite element analysis software (ANSYS) respectively. Finally, the results indicate that vertical loads and elastic modulus have great impact on the maximum deflection of masonry walls. Numerical computations show that the shell element of SHELL63 is well used in analysis of the internal force and deflection of masonry walls out-of-plane loaded.
Experimental Study on Compression Performance of Cavity Wall Filled with Insulation
Authors: Yang Chun Xia , Wu Ya Ying , Yang Wei Jun , Zheng Qi Sheng , Shen Ji Mei
Published: July 2012

The thickness or the type of insulating material of cavity wall can be changed in order to satisfy different requirement of thermal insulation properties, so it suits for the hot-summer and cold-winter zone. The static test of 16 pieces of cavity wall with different depth-thickness ratio and different eccentricity has been carried out in this paper, and the failure patterns of the cavity wall, the feature of out-of-plane deformation, the characteristic of vertical deformation and the impact of binding rebar have also been analyzed. As result shows that there is interaction between the interior piece and the external piece of wall under vertical loading which leads to the improvement of the compression capacity. With theoretical analysis, a formula of vertical compression capacity of cavity wall with insulation is proposed. The result calculated by the formula is coincided with the data obtained by the test.
24m Steel Roof Truss Static Test Research of Changchun FAW-Volkswagen Golf Shop
Authors: Yang Yan Min , Xie Xiao Juan
Published: July 2012

The steel roof truss rod is widely used in Chinese building industrue, because of the reasonable force, the design and simple construction, the good economic indicators, attractive appearance and many other advantages. Based on a pin 24m steel roof truss static test research and the results, which is based on the rigid and hinged to calculate, show that the steel roof truss which has the property that the web member axis intersection point and the chord member centroid are coincident, is in a good agreement according the calculation of rigid or hinge compared with the actual stress state.
Seismic Tests on Square Thin-Walled Steel Tubular Columns Filled with Demolished Concrete Lumps
Authors: Wu Bo , Zhao Xin Yu , Zhang Jin Suo , Liu Qiong Xiang
Published: July 2012

This paper presents a most recent experimental work for evaluating the seismic behaviors of square thin-walled steel tubular columns filled with demolished concrete lumps (DCLs). Fifteen specimens with 300 × 300 mm square section, including 10 columns filled with DCLs and 5 reference columns without DCLs, were tested under combined axial compression and lateral cyclic loading. The parameters considered in the tests are: replacement ratio of DCLs, thickness of steel tube, and axial load ratio. Research findings indicate that the seismic performances of square thin-walled steel tubular columns filled with DCLs are similar to the benchmark columns without DCLs, and the square thin-walled steel tubular columns filled with DCLs also exhibit acceptable ductilities and energy dissipation abilities.
A Review of Laser Doppler Vibrometry for Structural Health Monitoring Applications
Authors: Staszewski Wieslaw Jerzy , bin Jenal Ruztamreen , Klepka Andrzej , Szwedo Mariusz , Uhl Tadeusz
Published: July 2012

Non-contact optical/laser measuring techniques are very attractive in many engineering applications. The paper demonstrates examples related to structural health monitoring. Various methods based on strain, vibration and ultrasound measurements are presented together with relevant references. Applications examples utilise in-plane and out-of-plane measurements taken by 1-D and 3-D laser Doppler vibrometers.
Distributed System for Monitoring of the Large Scale Infrastructure Structures Based on Analysis of Changes of its Static and Dynamic Properties
Authors: Gałęzia Adam , Gontarz Szymon , Jasiński Marcin , Mączak Jędrzej , Radkowski Stanisław , Seńko Jarosław
Published: July 2012

The complexity and diversity of civil engineering structures impose requirements on the monitoring systems, which are difficult to be satisfied. In the paper the concept of the distributed diagnostic system capable of monitoring the technical state of critical elements of large infrastructure objects like steel trusses, supermarket buildings, exposition halls, bridges etc. is discussed. Adaptation of such systems is essential for online assessment of technical state of the infrastructure objects and could limit the possibility of catastrophic disasters with loss of people. As a source of information data from strain gauges, passive magnetic field sensors and acceleration sensors applied to the construction are considered. For the process of selection of sensors and diagnostic methods the mathematical model of the construction and the physical test stand were used.
Energy Management Systems for Energy Harvesting in Structural Health Monitoring Applications
Authors: Arnold M. , Featherston C.A. , Pearson Matthew R. , Lees J. , Kural Aleksander
Published: July 2012

Autonomous structural health monitoring systems with independent power sources and wireless sensor nodes are increasingly seen as the best solution for monitoring a diverse range of machines and structures including pumps, bridges and aircraft. Powering these systems using harvested energy from ambient sources provides an attractive alternative to the use of batteries which may be either inaccessible for routine maintenance or unsuitable (for example in aerospace applications). A number of techniques are currently being considered including harvesting energy from vibration and thermal gradients. Harvesting energy can however lead to a highly variable power supply in opposition to the requirements of a wireless sensor node which requires continuous standby power with an additional capacity for power peaks during transmission of data. A power management system with embedded energy storage is therefore necessary in order to match supply and demand. Due to the low levels of power harvested in a number of applications, an important factor in the design of such a system is its efficiency to ensure sufficient power reaches the sensor node. Based on the requirements for a simple power management system for thermoelectric power harvesting consisting of a rectifier, a DC/DC convertors and a battery, this paper first examines the possibilities in terms of basic components with a number of commercially available units tested and characterised. Potential designs for a management system incorporating these components are then discussed and a blueprint for an optimal system is suggested.
Rail Vehicle's Suspension Monitoring System - Analysis of Results Obtained in Tests of the Prototype
Authors: Melnik Rafał , Kostrzewski Mariusz
Published: July 2012

The active safety issue of rail vehicles is important for providing regular transportation services and minimizing the risk of accidents. One of the solutions to the problem of assuring high level of active safety is applying the condition monitoring of suspension system. Suspension, as a part of running gear, is crucial for providing proper running behavior stability. The increasing demands on improving safety of railway transport has led to development of prototype of rail vehicles' suspension monitoring system at Monitoring of Technical State of Construction and Evaluation of its Lifespan Project (MONIT). The idea of the system is qualitative assessment of suspension condition based on acceleration signals measured on bogie frames, wheels and body. The monitoring system prototype has been tested on passenger and freight cars in two states of suspension condition: nominal and damaged. Experimental tests have been performed on experimental track near Zmigrod in Poland. This paper presents analysis of the results obtained from the tests of the rail vehicles' suspension monitoring system prototype.
Some Recent Developments in Structural Health Monitoring
Authors: Barthorpe R.J. , Cross E.J. , Papatheou E. , Worden Keith
Published: July 2012

This paper is concerned with reporting some recent developments in Structural Health Monitoring (SHM) research conducted within the Dynamics Research Group at the University of Sheffield. The particular developments discussed are concerned with arguably the two main problems facing data-based approaches to SHM, namely: how to obtain data from damage states of a structure for supervised learning and how to remove environmental and operational effects from data when unsupervised learning (novelty detection) is indicated.
Structural Health Monitoring of Composite Scarf Repairs with Guided Waves
Authors: Pavlopoulou Sofia , Soutis Costas , Staszewski Wieslaw Jerzy
Published: July 2012

The interest in composite repair technologies has been recently increased following the wide applications of composite materials in aerospace industry. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance. Scarf repairs offer great advantages compared to external patch repairs since they provide higher stiffness by matching ply to ply the original structure and by reducing stress discontinuities in the repaired region. Ultrasonic guided waves have been extensively used for the health monitoring of complex structures due to their remarkable ability of defect recognition. The authors have previously investigated the extraction of the instantaneous characteristics of Lamb waves for the monitoring of an aluminium repaired structure, highlighting the potential use of such waves in the inspection of repaired structures [1]. In the current study, the behaviour of a scarf repair was monitored with guided ultrasonic waves excited by low profile, surface bonded piezoceramic transducers under longitudinal tensile loading. Appropriate damage indices were extracted and the results were correlated with images taken through a 3-Dimensional Digital Image Correlation (3-D DIC) technique. The correlation of the extracted features with the early stage damage is performed and conclusions about the recovered strength through the scarf repair are deduced. Finally the study compares results obtained from the on-line analysis and from off-line techniques such as ultrasonic C-scanning and X-ray radiography.
Vibrothermographic Testing of Structures
Authors: Szwedo Mariusz , Pieczonka Łukasz , Uhl Tadeusz
Published: July 2012

The paper investigates practical aspects of vibrothermographic testing of structures. Two application cases of vibrothermography are presented and discussed. The examples are weld test specimens and a military aircraft skin. Measurements have been performed with use of an in-house vibrothermographic testing system. In case of welded specimens a series of carbon steel test samples with different flaw types have been investigated. In case of aircraft testing, field measurements have been performed on a wing and fuselage sections in order to assess their structural integrity. The paper presents thermal image processing technique that allows to increase the quality and readability of the results coming from field measurements with poor ultrasonic excitation and with low thermal response from the structure. The paper is concluded with the discussion on applications of vibrothermographic testing in Structural Health Monitoring.
Artificial Neural Network Based Fault Diagnosis of IC Engines
Authors: Chen Jian , Randall Robert , Peeters Bart , Desmet Wim , Van der Auweraer Herman
Published: July 2012

Fault diagnosis is important to avoid unforeseen failures of IC engines, but normally requires an expert to interpret analysis results. Artificial Neural Networks are potential tools for the automated fault diagnosis of IC engines, as they can learn the patterns corresponding to various faults. Most engine faults can be classified into two categories: combustion faults and mechanical faults. Misfire is a typical combustion fault; piston slap and big end bearing knock are common mechanical faults. The automated diagnostic system proposed in this paper has three main stages, each stage including three neural networks. The first stage is the fault detection stage, where the neural networks detect whether there are faults in the engine and if so which kind. In the second stage, based on the detection results, the severity of the faults was identified. In the third stage, the neural networks localize which cylinder has a fault. The critical thing for a neural network is its input feature vector, and a previous study had indicated a number of features that should differentiate between the different faults and their location, based on advanced signal processing of the vibration signals measured for different normal and fault conditions. In this study, an advanced feature selection technology was employed to select the significant features as the inputs to networks. The input vectors were separated into two groups, one for training the network, and the other for its validation. Finally it has been demonstrated that the neural network based system can automatically differentiate and diagnose a number of engine faults, including location and severity.
Condition Monitoring System for Light Rail Vehicle and Track
Authors: Firlik Bartosz , Czechyra Bartosz , Chudzikiewicz Andrzej
Published: July 2012

Condition monitoring and fault detection systems are becoming increasingly important in rail vehicles maintenance and operation, ensuring safety and reliability improvement. Light rail systems are not the main target for this trend, because of low operational speed and lower safety factors. Nevertheless public transport operators begin to pay a closer attention to the technical state monitoring of vehicle and track, in order to reduce maintenance cost and increase safety and ride comfort for passengers, which is an important challenge for public transport competitiveness in XXI century. The paper describes the main concept of the innovative on-board condition monitoring system for light rail vehicle and track. Functional requirements, assumptions and procedures are described, as well as the on-board data acquisition unit with necessary transducers, which number, function and technical parameters were optimized during the research phase of the project. The prototype of the presented system is now being tested in normal operating conditions.
Damage Detection in Gearboxes Considering Intermittent Faults and Time-Varying Loads
Authors: Antoniadou Ifigeneia , Manson G. , Staszewski W.J. , Worden K.
Published: July 2012

The paper develops a simplified two-degree-of-freedom gear model that simulates vibration signals under operational conditions similar to those of wind turbine gearboxes. Nonlinear characteristics were included in the model in order to obtain more realistic results. The two types of faults examined in this study are common periodic gear tooth faults and intermittent gear tooth faults. The latter type of faults appears to be a novel idea in the condition monitoring field. Transient loads are also taken into consideration in this study since such loads are commonly observed in wind turbine systems, and make it even more difficult to detect damage. The analysis of the obtained signals is done using a relatively new method, the Empirical Mode Decomposition (EMD) that works well for nonstationary and nonlinear signals.
Development, Validation and Comparison of Higher Order Finite Element Approaches to Compute the Propagation of Lamb Waves Efficiently
Authors: Duczek Sascha , Willberg Christian , Schmicker David , Gabbert Ulrich
Published: July 2012

When considering structural health monitoring (SHM) applications efficient and powerful numerical methods are required to predict the behavior of ultrasonic guided waves and to design SHM systems. The existing commercial explicit finite element analysis tools based on standard linear displacement elements quickly reach their limits when applied to ultrasonic waves in thin plates, so called Lamb waves. It is known that the required temporal and spatial resolution causes enormous computational costs. One resort to overcome this problem is the application of special finite elements utilizing higher order polynomial shape functions (p> 2). The current paper is focused on the development of such higher order finite elements and the verification of their accuracy and performance. In the paper we compare and evaluate the capabilities of spectral finite elements,p-version finite elements and isogeometric finite elements. Their advantages and disadvantages with respect to ultrasonic wave propagation problems are discussed and their properties are demonstrated by solving a benchmark problem. Higher order finite elements with varying polynomial degrees in longitudinal and transversal direction (anisotropic ansatz space) are investigated and convergence studies are performed. The results of the convergence studies are summarized and a guideline to estimate the optimal discretization is prepared. If the required accuracy is known, the proposed guideline provides a helpful means to determine both the element size and the polynomial degree template for a given model.
Evaluation of Silicon Substrates Fabricated by Seeding Cast Technique
Authors: Tachibana Tomihisa , Sameshima Takashi , Kojima Takuto , Arafune Koji , Kakimoto Koichi , Miyamura Yoshiji , Harada Hirofumi , Sekiguchi Takashi , Ohshita Yoshio , Ogura Atsushi
Published: July 2012

We evaluated the properties of crystalline defects in silicon substrate, and clarified the origin of small-angle grain boundaries. In order to eliminate the effects of grain boundaries, the ingot was fabricated by unidirectional solidification technique with seed crystal. In single-crystalline region, Σ3 twin boundaries and SiC precipitates were observed near the seed crystal. No obvious relationship between twin boundaries and precipitates was observed. These defect decreased once and the precipitations appeared again. The density of precipitates increased through the crystal growth procedure. These precipitates were consisted of Si, C, and N. After the precipitation density increased, the small-angle grain boundaries appeared and some precipitates were observed at the boundaries. We considered the precipitations consisted of light element impurities such as C and N were one of the major origins of the small-angle grain boundary generation.
Combined EL and LBIC Study of the Electrical Activity of Defects in Solar Cells Based on Innovative Wafers Grown by Casting Methods
Authors: Moralejo Benito , Hortelano Vanesa , Martínez Oscar , Jiménez Juan , González Miguel Angel , Guerrero Ismael , Parra Vicente
Published: July 2012

In this paper we combine LBIC and EL measurements of commercially multi-crystalline silicon solar cells, in order to obtain detailed information about the electrical activity around defect areas. This integrated analysis is suitable for the study of different crystal defects at both micrometric and full wafer scale. In particular, the electrical activity of some defect areas is studied in detail by means of highly spatially-resolved LBIC maps, showing important differences in their behaviours. A discussion about the origin of these differences is presented.
Analysis of Lattice Distortion in Multicrystalline Silicon for Photovoltaic Cells by Synchrotron White X-Ray Microbeam Diffraction
Authors: Shimura Takayoshi , Matsumiya Takuya , Morimoto Naoki , Hosoi Takuji , Kajiwara Kentaro , Chen Jun , Sekiguchi Takashi , Watanabe Heiji
Published: July 2012

A synchrotron white x-ray microbeam diffraction method was employed to investigate lattice distortion in multicrystalline silicon for photovoltaic cells. The measurements were carried out by scanning the sample, and transmission Laue patterns were observed at each position on the sample. Intensity and position maps of the Laue spots showed the distribution of the crystalline quality of the grains and the bending of the lattice planes. Strain and bending distributions were extracted from an analysis of Laue spots at diagonal positions, and these were compared with those obtained by other techniques.
Spectroscopic Investigation of Silicon Polymorphs Formed by Indentation
Authors: Schade Martin , Leipner Hartmut S. , Fränzel Wolfgang
Published: July 2012

Silicon polymorphs have been prepared by means of scratching or indentation of Si(100) surfaces. Different indenter types have been used in order to validate the independence of silicon polymorph formation from indenter geometry. The formation of silicon polymorphs could be verified by registering the loading-displacement curves. Related to the maximum loads applied, only the formation of the meta-stable silicon phases SI-III, Si-IV and Si-XII has been observed, what has been verified by Raman spectroscopy. Four different ways of the preparation of electron transparent samples are presented and compared. Finally, a first electron energy loss spectrum of certain silicon polymorphs is shown.
DLTS Study of Pd-H Complexes in Si
Authors: Abe Sunao , Goura Ryuichi , Shimoe Koichi , Kamiura Yoichi , Yamashita Yoshifumi , Ishiyama Takeshi
Published: July 2012

We have observed five electron traps with energy levels at 0.16, 0.30, 0.40, 0.53 and 0.67 eV below the conduction band in Pd and H doped Si by DLTS technique. Successive annealing at 373 K and 473 K for 30 min respectively caused two levels at Ec-0.16 eV and Ec-0.67 eV to disappear and simultaneously a new level to emerge at Ec-0.19 eV. From such annealing behavior and the comparison of the energy levels observed in the present study with those in the literature, we assign them to various Pd and H related defects as follows, Pd-H2: Ec-0.16 eV and Ec-0.67 eV, Pd acceptor: Ec-0.19 eV, Pd-H3: Ec-0.30 eV, Pd-H1: Ec-0.40 eV.
Rapid Imaging of Carrier Density of Si Using Reflectance Measurement in the Terahertz Region
Authors: Hamano Akihide , Takatsu Yoshinobu , Ohno Seigo , Minamide Hiroaki , Ito Hiromasa , Usuki Yoshiyuki
Published: July 2012

Rapid imaging of the carrier density of n-type silicon (Si) was carried out at the rate of 2 s per point using a terahertz wave of 4.4 THz generated from a tunable terahertz source. Reflectance of 4.4 THz as a function of carrier density was calculated using a simple Drude model. The carrier densities obtained from the terahertz imaging were 1 × 1018 cm−3 and 3 × 1018 cm−3, respectively.
Effect of Si3N4 Coating on Strain and Fracture of Si Ingots
Authors: Jiptner Karolin , Harada Hirofumi , Miyamura Yoshiji , Fukuzawa Masayuki , Sekiguchi Takashi
Published: July 2012

This study is concerned with the effect of reduced Si3N4 coating during Si growth carried out by the directional solidification cast method. Three crystals were grown and compared in terms of cracking behavior and strain distribution. It was found, that the outer areas of the grown Si ingots exhibit much higher strain than the center pieces and this corresponds with the appearance of cracks in higher density in the outer edges of the crystals. It was also found that cracks mainly propagated in vertical direction and less in horizontal direction due to the temperature gradient during growth.
XRD Investigation of the Crystalline Quality of Sn Doped β-Ga2O3 Films Deposited by the RF Magnetron Sputtering Method
Authors: Kudou Jyun , Funasaki Suguru , Takahara Motoki , Tsunoda Isao , Takakura Kenichiro , Ohyama Hidenori , Nakashima Toshiyuki , Shibuya Mutsuo , Murakami Katsuya , Simoen Eddy , Claeys Cor
Published: July 2012

For the purpose of increasing the conductivity of β-Ga2O3 films, Sn doping in the β-Ga2O3 films has been explored using co-sputtering. Growth of β-Ga2O3 was confirmed by the XRD pattern for the undoped sample. However, it is shown that the Ga2O3 phase is transformed from the β to the γ phase by Sn doping, because of the increase of the phase transition temperature from the γ to the β phase. To improve the crystalline quality, additional annealing at 900°C for 60 min is performed to the Sn doped film. The XRD peaks corresponding with β-Ga2O3 could be confirmed after the additional annealing.
Frank Partial Dislocation in 4H-SiC Epitaxial Layer by MSE Method
Authors: Hamada Shinkichi , Yoshioka Hisashi , Kawami Hiroshi , Nakamura Nobuhiko , Setoguchi Yoshitaka , Matsunami Toru , Nishikawa Kimito , Isshiki Toshiyuki
Published: July 2012

We have been trying to improve a quality of crystal, using the metastable solvent epitaxy (MSE) method, one of the solution methods. In MSE, a Frank-type fault is formed by conversion of a threading screw dislocation (TSD) in the substrate. To study the status of the growth, we performed plane-viewed TEM observation. Analysis of Burgers vectors in the TEM image showed Frank PDs (Partial Dislocations) which do not include a components and Frank PDs which include a components. The total Burgers vectors of Frank-type fault including a components are represented as b=a/3+c, which indicates some TSDs in the substrate also include a components.
Separation of the Driving Force and Radiation-Enhanced Dislocation Glide in 4H-SiC
Authors: Maeda Koji , Hirano Rii , Sato Yuki , Tajima Michio
Published: July 2012

Anomalous expansion of stacking faults (SFs) induced in 4H-SiC under electronic excitations is driven by an electronic force and is achieved by enhanced glide of partial dislocations. An experimental attempt to separate the two physically different effects has been made by conducting photoluminescence (PL) mapping experiments which allowed simultaneous measurements of partial dislocation velocity and SF-originated PL intensity the latter of which is proposed to be related to the driving force for SF expansion through the density of free excitons planarly confined in the SF.