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Fatigue Failure Analysis for Bolt-Nut Connections having Slight Pitch Differences using Experimental and Finite Element Methods
Get PDFIn this paper, fatigue failure is considered, for bolt-nut connections, when a slight pitch difference is introduced between the bolt and the nut. To improve the fatigue life, three types of pitch difference are produced on the specimens and the experimental results are compared and discussed in terms of FEM analysis. Considering the standard bolt-nut
connection of α=0 μm, the bolt fracture does not happen at the No. 1 thread by introducing a slight pitch difference of α=5 μm and α=15 μm, as observed from the experiments. Furthermore, it is found that the fatigue life can be extended by introducing suitable pitch differences. The effect of bolt-nut fitted clearance, on the fatigue failure is also investigated
A Selective G-Quadruplex DNA-Stabilizing Ligand Based on a Cyclic Naphthalene Diimide Derivative
Get PDFA cyclic naphthalene diimide (cyclic NDI, 1), carrying a benzene moiety as linker chain, was synthesized and its interaction with G-quadruplex DNAs of a-core and a-coreTT as a human telomeric DNA, c-kit and c-myc as DNA sequence at promoter region, or thrombin-binding aptamer (TBA) studied based on UV-VIS and circular dichroism (CD) spectroscopic techniques, thermal melting temperature measurement, and FRET-melting assay. The circular dichroism spectra showed that 1 induced the formation of different types of G-quadruplex DNA structure. Compound 1 bound to these G-quadruplexes with affinities in the range of 106–107 M−1 order and a 2:1 stoichiometry. Compound 1 showed 270-fold higher selectivity for a-core than dsDNA with a preferable a-core binding than a-coreTT, c-kit, c-myc and TBA in the presence of K+, which is supported by thermal melting studies. The FRET-melting assay also showed that 1 bound preferentially to human telomeric DNA. Compound 1 showed potent inhibition against telomerase activity with an IC50 value of 0.9 μM and preferable binding to G-quadruplexes DNA than our previously published cyclic NDI derivative 3 carrying a benzene moiety as longer linker chain
鋼製軸と焼嵌接合された加熱炉用セラミックローラーにおける接合部の強度と軸の抜け外れに関する研究
No full text九州工業大学博士学位論文 学位記番号:工博甲第393号 学位授与年月日:平成27年9月25日1. Introduction || 2. Ceramic/Steel Joint Selection for the Ceramic Roller Used under Room
Temperature and High Temperature || 3. Proposal for New Hearth Roller Consisting of Ceramic Sleeve and Steel Shaft Used in the Heat Treat Furnace || 4. Failure Analysis for Coming out of the Shaft from Shrink-fitted Ceramic Sleeve || 6. Summar
ビデオからの移動物体の検出に関する研究
Get PDF九州工業大学博士学位論文 学位記番号:工博甲第381号 学位授与年月日:平成27年3月25日1 Introduction||2 Moving Object Detection Based on the Update of a Background Model||3 Moving Object Detection Employing a Moving Camera||4 Performance of the Method||5 Conclusion||In recent years, the video surveillance system for security and a driving safety system on the car have been growing rapidly. The video surveillance system has grown from a manual system to a fully autonomous system, whereas a driving safety system has evolved from a parking safety system to a collision avoidance system. The system requires a good ability to detect a moving object so as to be a reliable system.
The problem that must be addressed in the detection of moving objects on a video is a dynamic background. In this thesis, we proposed a moving object detection method using sequential inference of the background to overcome the problem of the dynamic background. The sequential inference of the background uses a series of previous image frames to create a model of the background image for the current frame. After a background model is obtained, then the background subtraction can be done.
The proposed method is applied to the video captured using a static camera and a moving camera. The detection of moving objects in a video captured by a moving camera is not as easy as the case using a static camera. Correspondence of pixels in the current image frame with the pixels of the previous image frame must be known in advance. The background model is formed using a bilinear interpolation of the previous image frame. The judgment of a pixel as the background or the foreground is done by subtracting the model of the background image from the current frame.
An important stage in this method is updating normal distribution of the pixels on a background model. A background model is formed based on the value of the normal distribution which is updated with each frame of a video. The originality of this thesis is to propose novel ways of updating the normal distribution to obtain an effective background model.
Experiments are performed on several videos. The results show that the proposed method can detect and extract moving objects that appear in a video scene successfully under various situations of the background. The effectiveness of the proposed method is recognized by recall, precision and F measure
マクロセルを用いた鉄筋コンクリートに対する防食技術の評価
No full text九州工業大学博士学位論文 学位記番号:工博甲第386号 学位授与年月日:平成27年3月25日Chapter 1 Introduction||Chapter 2 Literature Review on Nitrite-based Corrosion Inhibitors||Chapter 3 Effect of Nitrite Ions on Steel Corrosion in Simulated Concrete Pore Solution||Chapter 4 Effect of Anodic and Cathodic Chloride Contents on themacrocell Corrosion and Polarization Behavior of Reinforcing Steel||Chapter 5 Effect of Nitrite ions on the Macrocell Corrosion and Polarization Behavior of Reinforcing Steel||Chapter 6 Effect of Steel Initial Surface Conditions on the Macrocell Corrosion and Polarization Behavior of Reinforcing Steel||Chapter 7 Effect of Water-Cement Ratio on the Macrocell Corrosion and Polarization Behavior of Reinforcing Steel||Chapter 8 Effect of Moisture Contents on the Macrocell Corrosion and Polarization Behavior of Reinforcing Steel||Chapter 9 Conclusions and RecommendationsIn reinforcing concrete structures, the corrosion prevention technique is usually evaluated by the use of microcell corrosion theory in which cathode and anode are coexisted, and is rarely evaluated based on macrocell corrosion theory in which cathode and anode are separated. In maceocell corrosion state, the macrocell potential difference and the macrocell polarization slopes and ratios of cathode and anode are the important parameters to control the magnitude ofmacrocell current. So based on macrocell corrosion theory, studying these parameters can lead us a deeper understanding of the mechanism of corrosion prevention techniques to inhibit corrosion.
In this study, the corrosion prevention technique is mainly focused on the nitrite-based corrosion inhibitor. The effect of nitrite on steel corrosion has been evaluated by the use of both microcell corrosion theory and macrocell corrosion theory. Some factors influencing themacrocell corrosion also has been investigated.
This dissertation is composed of nine chapters. In Chapter 1 the research backgrounds, purposes, significance and contents were introduced. In Chapter 2, the influence of nitrite on the properties of fresh and hardened concrete was introduced, the inhibition mechanism of nitrite ions was explained, and the inhibiting efficiency of nitrite on the corrosion of steel embedded in simulated pore solution and concrete was discussed and summarized.
In view of the existing problems in Chapter 2 and based on the microcell corrosion theory, then in Chapter 3, the influence of nitrite concentration on the corrosion of steel immersed in three simulated pH environments containing chloride ions or sulfate ions was investigated by comparing and analyzing the change of half-cell potential, the change of threshold level of Cl- or SO42-, the change of threshold level of NO2-/Cl- or NO2-/SO42- mole ratio. The corrosivity of chloride ions against sulfate ions also had been discussed in three different pH environments containing various nitrite concentrations. The results indicated that the presence of nitrite could effectively inhibit the corrosion of steel. Chloride threshold level and sulfate threshold level were not only increased with increasing of nitrite concentration but also affected by pH. Highly alkaline environment played an important role in assisting nitrite to inhibit corrosion. For chloride-induced corrosion, using NO2-/Cl- mole ratio as the parameter to guarantee the inhibition effect was suitable in highly alkaline environment, but not appropriate in weakly alkaline and neutral environments. Chloride-induced corrosion was more prone to initiate than sulfate-induced corrosion in highly alkaline environment.
Based on the macrocell corrosion theory, in Chapter 4, the effect of anodic and cathodic chloride contents on the macrocell corrosion and polarization behavior of reinforcing steel embedded in cement mortars were investigated by comparing the magnitude of macrocell current and analyzing the macrocell polarization ratios and slopes of anodic and cathodic steels. The results indicated that the higher cathodic chloride content could accelerate the cathodic reaction of cathode and make the controlling mode of macrocell corrosion changed from cathodic control to mixed control or anodic control. The higher anodic chloride content could accelerate the anodic reaction of anode and make the macrocell corrosion more controlled by cathode. So in the real reinforcing concrete structures, due to the existence of large cathode and small anode, the acceleration of macrocell corrosion caused by higher anodic chloride content could be confirmed.
After understanding the effect of anodic and cathodic chloride contents on the macrocell corrosion behaviors of cathode and anode, in Chapter 5, based on macrocell theory, the inhibiting effect of nitrite on steel corrosion was evaluated. In this chapter, nitrite solutions with various concentrations were filled into the holes of mortar around anodic steel. The change of macrocell potential difference and current, the change of macrocell polarization ratios and slopes of cathode and anode were compared and analyzed. The effect of nitrite ions on the relationship between macrocell current density and microcell current density were also investigated. The results indicated that nitrite was more effective in inhibiting the macrocell corrosion than the microcell corrosion. The presence of adequate nitrite on the surface of anodic steel could effectively inhibit the anodic reaction of anode and was prone to make the macrocell corrosion less controlled by cathode.
Then in the following Chapter 6, Chapter 7, and Chapter 8, factors influencing the macrocell corrosion and polarization behavior of steels were investigated by comparing the magnitude of macrocell current and analyzing the macrocell polarization ratios and slopes of anodic and cathodic steels. These factors were related to the steel initial surface conditions, water-cement ratios and moisture contents of mortar. The results also indicated that the initial polished surface had a higher corrosion resistance to inhibit the macrocell current than the scaled surface that formed in the production process. The lower water-cement ratio could decrease the macrocell potential difference and increase the macro-cell polarization resistance of both cathode and anode, both of which resulted in the decrease of macrocell current. The moisture contents of cathode played an important role in weakening the macrocell corrosion. The increase of moisture contents of cathode limited the transport of oxygen, decreased the oxygen concentration of cathode and thus greatly weakened the cathodic reaction of cathode, which not only resulted in the increase of macro-cell polarization ratio of cathode but also inhibited the macro-cell current.
Finally, in Chapter 9, the main conclusions of this study was summarized, the limitations of this research was pointed out and the direction of further studies was suggested
産業用電力線通信システムに関する研究
No full text九州工業大学博士学位論文 学位記番号:情工博甲第305号 学位授与年月日:平成27年6月30日第1章 序論||第2章 既存システムの課題||第3章 産業用電力線通信システムの提案||第4章 同期通信による雑音影響の低減方法||第5章 LLR による雑音影響の低減方法||第6章 結
三角形数え上げに基づくグラフ分割手法によるコミュニティ抽出
No full text九州工業大学博士学位論文 学位記番号:情工博甲第296号 学位授与年月日:平成27年3月25日1 Introduction||2 Community Extraction from Graphs||3 Quasi-k-truss Decomposition for Bipartite Graphs||4 Experiments and Evaluations||5 Conclusion and Future WorkA community in a graph is a group of nodes holding similar characteristics or sharing common properties within the graph. It is also referred to as a cluster or a module of graphs.
A graph is considered to have the community structure if its nodes can be clustered into several subsets of nodes within a certain degree or density. The community structure is, therefore, one of the most relevant characteristics of graphs. The community structure has attracted tremendous interest in recent years for its various scientific applications. The community structure represents real world network systems, and models many kinds of real world relations, such as biological networks, web pages and social networks. Furthermore, the community structure can be used for analyzing the hierarchical organizations of real world network systems, and for understanding the structure of complicated network systems.
Various efficient and effective techniques have been proposed and developed for identifying communities in graphs.
Among various community extraction and graph analysis techniques, graph decomposition techniques play a vital role in identifying communities in graphs. The graph decomposition is to divide a graph into a set of dense subgraphs interpreted as communities so that the communities in the graph can be identified and extracted. Then, it is feasible and available to focus on smaller but more crucial areas of the graph when the input graph becomes exceedingly massive. As a definition of dense subgraph, the k-truss formed by triangles is one of the simplest cohesive subgraphs since triangle is the smallest non-trivial clique. By the definition, every edge of the dense subgraph to be decomposed is contained in at least (k .2)-triangle. The task of k-truss decomposition is to find all trusses in a graph.
The cohesive subgraphs in a graph can be extracted hierarchically based on the k-truss decomposition method. A triangle (or 3-clique), consists of three fully connected nodes. It is the densest substructure in a graph. Therefore, the k-truss keeps a good trade-off between computational efficiency and clique approximation. However, the k-truss is not available for bipartite graphs because no triangle occurs in bipartite graphs. The k-truss decomposition method is not applicable to bipartite graphs.
In this research, by adding additional edges to a bipartite graph, we extend the notion of k-truss to bipartite graphs, name it the quasi-k-truss, so that the communities as cohesive subgraphs can be extracted from a bipartite graph. Then, the original bipartite graph G is transformed to another graph G′. When a k-truss T is computed from G, the quasi-k-truss is the subgraph whose edges are included in both T and G′, that is, the graph obtained by removing all additional edges from T. Every edge in the quasi-k-truss is contained in at least (k?2)-triangle while a bipartite graph contains no triangles inside. In order to extract triangles virtually in a given bipartite graph, we introduce the auxiliary edges. Alternative to the originally existed edges, the auxiliary edges do not originally exist in bipartite graphs. An auxiliary edge is generated between any two nodes in the same node set if these two nodes share at least one common neighbor node in the other node set. The set of auxiliary edges is generated among all nodes with the same characteristics in a given bipartite graph. The set of auxiliary edges is generated for forming triangles in a given bipartite graph. According to the notion of quasi-k-truss of bipartite graphs, the quasi-k-truss decomposition algorithm is developed for decomposing a bipartite graph, and extracting communities represented by dense subgraphs from a bipartite graph. In the proposed algorithm, initially, a set of auxiliary edges is generated to form triangles in a given bipartite graph. Then, to extract communities from a bipartite graph, the number of triangles containing an edge of the bipartite graph is counted. Communities can be extracted hierarchically from a bipartite graph based on an iterated procedure. In order to improve the computational efficiency, some data structures have been applied to the implementation of the proposed algorithm. Finally, experiments for real world datasets have been conducted to verify the effectiveness and efficiency of the proposed method compared with baseline methods
A Study on the Possibility of Scribbling of Tagging and Sticker - A Case Study in a Station District in Kitakyushu City -
Get PDFキサンテン金属化合物の合成と特性評価、およびエポキシ樹脂潜在性触媒への応用
No full text九州工業大学博士学位論文 学位記番号:生工博甲第246号 学位授与年月日:平成27年9月25日1. Introduction||2. Chapter 2. Experimental methods||3. Zinc xanthates with varying alkyl chains on curing||4. Effect of Alkyl-metal xanthates with varying metals on curing of epoxy resin||5. Investigation with gallium (III) xanthate and standard catalyst||6. General ConclusionCured epoxy resins have emerged as one of the most demanding industrial materials due to their properties such as high stiffness, adhesive nature and environmental stability. Their versatile nature makes it valuable with tremendous application potential ranging from sports goods to aerospace industry.
Cured epoxy is a product of processed epoxy oligomer or polymer into a three dimension network generated by employing curing catalysts. The conventional curing catalysts however suffer from serious drawback of premature curing even undesired at ambient conditions limiting its pot-life. Therefore utilization of latent catalyst for thermoset applications is highly desired to extend the working life of a formulated mixture by passivating the activity of the catalyst until triggered by the external stimulus. The impetus for using latent catalysts is to impart the ability for developing the fully formulated resin systems with long storage life that can be applied directly by the end user. This, in turn, helps guaranteed consistency and improve process efficiency. To attain this, core shell encapsulation or matrix encapsulation are being currently used but they suffer from the problems like diffusion through the thermoset after release and sluggish release kinetics respectively.
We have found that metal sulfides exhibit the curing of epoxy resin composite like conventionally used acid and base catalysts. Normally such catalyst start reacting immediately having limitation on the pot-life. Since metal sulfides are generally insoluble in the solvent and by homogeneously mixing with the ingredients of the epoxy resin composite their latent catalytic property cannot be effectively utilized. Metal xanthates are well known soluble precursors for the metal sulfides whose solubility can be controlled by judicious modification of alkyl chain. Just upon heating to the threshold temperature, they generate the metal sulfide in the system releasing only the gaseous bi-products.
This dynamic latent capability of metal xanthates to form catalytically active metal sulfides was put to use in this current study. This thesis explores and demonstrates the investigation of metal xanthates as potential latent thermal catalysts for curing of epoxy resins