3164 research outputs found
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機械学習を用いた積雪粒子画像の自動判定法
Get PDFThis study proposes the automatic determination method of snow particle images using machine learning. A visual method
using a gauge and loupe is generally used to determine snow type, however, this requires skill and is prone to an error. To
resolve this issue, we focused on machine learning, built and evaluated a snow particle image determination model and
then developed a smartphone application for practical application of the technology. Although there were issues with
determining layers showing multiple types of snow quality, good determination results were obtained for snow type with
characteristic shapes, such as new snow and depth hoar.journal articl
ICE JAM EXPERIMENT AND SIMULATION AROUND BRIDGE PIERS
Get PDFThis study aimed to clarify the phenomenon of ice jams generated around bridge piers. The onedimensional ice jams calculation model was proposed. This model is composed of water flow, ice flow and ice jams. In order to check the accuracy of this model, we conducted an ice jam experiment. The section of this experiment waterway is compound cross-section. The time series phenomenon of ice jams generated around bridge piers was able to be investigated in the experiment. This calculation model was able to simulate water level variation by ice jams. In order to improve calculation accuracy, we understood that it was important to consider the influence of ice jams on water flow appropriately in this model.journal articl
Geometric Modeling and 3D Printing Using Recursively Generated Point Cloud
Get PDFAbstract: Previous studies have reported that a recursive process called the point cloud creation
algorithm (PCA) that generates a point cloud is useful for reverse engineering a planner shape.
This study elucidates the characteristics of the parameters used in the recursive process as well as its
ability in geometric modeling and 3D printing of 3D shapes. In the recursive process, three constants
(center point, initial distance, and initial angle) and two variables (instantaneous distance
and instantaneous rotational angle) are employed. The shape-modeling characteristics of the constants
and variables are elucidated using some commonly used shapes (straight-line, circle, ellipses, spiral,
astroid, S-shape, and leaf-shape). In addition, the shape-modeling capability of the recursive
process as a whole is quantified using two parameters called the radius of curvature and aesthetic
value. Moreover, an illustrative example that shows the ecacy of the recursive process in virtual
and physical prototyping of a relatively complex 3D object is presented. The results show that reverse
engineering performed by the recursive-process-created point cloud is free from computational
complexity compared to reverse engineering performed by the 3D-scanner-created point cloud.
As such, the outcomes of this study enrich the field of reverse engineering.journal articl
Quality Improvement of a Gear Transmission by Means of Genetic Algorithm
Get PDFThe article deals with the issue of quality improvement of a gear transmission by optimizing its geometry with the use of genetic algorithms. The optimization method is focused on increasing productivity and efficiency of the pump and reducing its pulsation. The best results are tested on mathematical model and automatically modelled in 3D be means of PTC Creo Software. The developed solution proved to be an effective tool in the search for better results, which greatly improved parameters of pump especially reduced flow pulsation.journal articl
ICE JAM FLOOD EXPERIMENT USING REAL ICE AROUND BRIDGE PIERS
Get PDF橋脚部におけるアイスジャム現象の解明を目的に，低水路と高水敷を設けた複断面水路を用いた実験を実施した．実験に用いた氷模型は，ポリプロピレンおよび実氷を用いた．本実験結果から以下のことが分かった．(1) アイスジャムにより氷模型の速度は減少し氷模型枚数は増加する．(2) アイスジャムにより氷模型は橋脚を迂回して高水敷へと流れて下流の低水路へと流下する．(3) アイスジャム発生後に，上流で氾濫が始まり，その後下流へと氾濫が始まる．(4) 氾濫速度は，流量が大きいほど速い．上流では氾濫速度はゼロに近づき，氾濫範囲は一定値となる．(5) アイスジャム発生地点の上流では水位が上昇し，直下流では水位が下降する．アイスジャム決壊後の直下流では水位が急激に上昇する．This study aimed to clarify the phenomenon of ice jams generated around bridge piers. We conducted an ice jam experiment. The section of this experiment waterway is compound cross-section. Polypropylene and actual ice were used for the ice model in this experiment. The study clarified the following. (1) By ice jams, the speed of the ice model decreases and the number increases. (2) The ice model was detoured at bridge piers and flowed on the high-water channel. And it was flowing into the low-water channel in the downstream. (3) After ice jam occurrence, Flooding begins from the upstream site. Later, Flooding flowed to the downstream site. (4) The flooding speed is fast when discharge is large. As time passes, the flooding area becomes the constant value. (5) In the ice jams site, the upstream water level went up, the downstream water level descended. The downstream water level has been increased suddenly after ice jams breaking.journal articl
Physicochemical Study on the Strength Development Characteristics of Cold Weather Concrete Using a Nitrite–Nitrate Based Accelerator
Get PDFThere has recently been an increased use of anti-freezing agents that are primarily composed of salt- and alkali-free calcium nitrite (Ca(NO2)2) and calcium nitrate (Ca(NO3)2) to promote the hydration reaction of concrete in cold weather concreting. Nitrite–nitrate based accelerators accelerate the hydration of C3A and C3S in cement more quickly when their quantities are increased, thereby boosting the concrete’s early strength and effectively preventing early frost damage. However, the connection between the hydrate formation behavior and the strength development characteristic over time has yet to be clearly identified. Therefore, in this study, a wide range of physicochemical reviews were carried out to clarify the relationship between the hydrate formation behavior and the strength development characteristics, both at an early age and at later ages, which results from the addition of nitrite–nitrate based accelerators to concrete in varying amounts. These accelerators also act as anti-freezing agents. The results show that an increased quantity of nitrite–nitrate based accelerators caused an increase in the early strength of the concrete. This was due to the formation of nitrite and nitrate hydrates in large amounts, in addition to ettringite containing SO42, which is generated during the hydration reaction of normal Portland cement at an early age. On the other hand, at later ages, there was a rise in nitrite and nitrate hydrates with needle crystal structures exhibiting brittle fracture behavior. A decrease in C–S–H gel and Ca(OH)2 hydrates, deemed to have caused a decline in strength on Day 3 and thereafter, was also observed.journal articl
Effect of crystallographic structure on self-preservation of methane-ethane mixed gas hydrate
Get PDFガスハイドレートの分解過程では，包接されるガスによっては本来不安定な条件下でも残存することが知られており，この効果は自己保存効果と呼ばれている．本研究は，比較的データの少ない混合ガスハイドレートの自己保存効果をラマン分光測定で検証した実験である．ガス混合比によって結晶構造の変化するメタン・エタン混合系で実験を行ない，自己保存効果の有無とガス組成および結晶構造との関係について考察した．journal articl