Self-Preservation of Turbulence Statistics in the Wall-Wake Flow of a Bed-Mounted Horizontal Pipe

This research article analyzed the self-preserving behaviour of wall-wake region of a circular pipe mounted horizontally over a flat rigid sand bed in a shallow flow in terms of mean velocity, RSS, and turbulence intensities. The study aims to investigate self-preservation using appropriate length and velocity scales.in addition to that wall-normal distributions of the third-order correlations along the streamwise direction in the wake region are analyzed. An ADV probe was used to record the three-dimensional instantaneous velocities for four different hydraulic and physical conditions corresponding to four cylinder Reynolds numbers. The results revealed that the streamwise velocity deficits, RSS deficits, and turbulence intensities deficits distributions displayed good collapse on a narrow band when they were non-dimensionalized by their respective maximum deficits. The wall-normal distance was non-dimensionalized by the half velocity profile width for velocity distributions, while the half RSS profile width was used in the case of the RSS deficits and turbulence intensities deficits distributions. The results indicate the self-preserving nature of streamwise velocity, RSS, and turbulence intensities in the wall-wake region of the pipe. The third-order correlations distributions indicate that sweep is the dominant bursting event in the near-bed zone. At the same time, ejection is the dominant bursting event in the region above the cylinder height.

Effect of Illumination on Human Drone Interaction Tasks: An Exploratory Study

With recent changes by the Federal Aviation Administration (FAA) opening the possibility of more areas for drones to be used, such as delivery, there will be increasingly more intera ctions between humans and drones soon. Although current human drone interaction (HDI) investigate what factors are necessary for safe interactions, very few has focused on drone illumination. Therefore, in this study, we explored how illumination affects users’ perception of the drone through a distance perception task. Data analysis did not indicate any significant effects in the normal distance estimation task for illumination or distance conditions. However, most participants underestimated the distance in the normal distance estimation task and indicated that the LED drone was closer when it wa s illuminated during the relative distance estimation task, even though the drones were equidistant. In future studies, factors such as the weather conditions, lighting patterns, and height of the drone will be explored.

Imaging the rupture zone of the 1912 Ganos earthquake using fault zone head waves from a local seismic network

<p>The Ganos Fault (GF) is the westernmost onshore segment of the North Anatolian Fault Zone (NAFZ) and was last activated in the Mw7.4 Ganos/Mürefte earthquake in 1912. The GF is a first order linear and a right lateral strike-slip fault with a locking depth of 8-17 km. A 40-station seismic array has been deployed between 2017 and 2020 along the GF to study the fault zone characteristics at depth. Fault Zone Head Waves (FZHW) are an important diagnostic signal to detect velocity contrast across fault and thus identify them as interfaces. A fault consisting of a sharp material contrast between different lithologies is expected to generate FZHW. They spend a large portion of their propagation paths refracting along the bimaterial interface. The head waves propagate with the velocity and motion polarity of the faster block, and are radiated from the fault to the slower velocity block where they are characterized by an emergent waveform with opposite motion polarity to that of the direct body waves. The FZHW are the first arriving phases at locations on the slower block with normal distance to the fault less than a critical distance. The high station coverage across the fault will allow us to observe micro-earthquake activity and FZHW close to the seismically active region of the GF throughout the entire seismogenic depth down to approximately 20 km thereby enhancing the resolution of seismological observations in that area. Preliminary results from MONGAN array allow to identify FZHWs at several stations in waveforms originating from events in the western Marmara Sea. We focus on the interpretation of a distinct first phase (FZHW) contained in the waveform coda that is well separated from the direct P wave. FZHWs are visible in many waveforms and have a specific time delay before the direct P wave arrivals at each station. Based on a polarization analysis of records at MONGAN stations, this first phase is interpreted as a FZHW at an interface near the study area. Its particle motion is consistent with FZHW and the direct P wave produced by the bimaterial interface. This is an indication of a bimaterial interface along the GF where the northern block is faster than the southern block.</p>

Simulation Machining of Hardened Gear Shaping and Finite Element Analysis

Existing simulation processing methods are difficult to obtain the tooth surface that is close to the actual processing. This paper proposes a high-precision simulation processing method for hard tooth surface gearing. Through the establishment of a high-precision cutter and tooth blank geometric model, analysis of the kinematics principle and meshing relationship between the cutter and tooth blank, combined with the functions of rotation, translation and Boolean operation in the 3D software, the high-precision shaping simulation processing of hardened gears is realized. By measuring the normal distance between the standard involute and the gear tooth profile, the tooth surface error analysis is completed. The simulation model is reconstructed, and the models are analyzed by finite element method (FEM) respectively, and the effectiveness of the method in this paper is verified by comparing the analysis results.

Principle and Method for Machining Face Gear with Developable Ruled Surface

The tooth surface of a face gear is recognized as un-developable ruled surface in tradition, which result in the problem that face gear generation using simple cutter with high efficiency and accuracy puzzled people for a long time. Applying the traditional shaping method for face gear generation in derivation of the tooth surface position vector, a space straight line equation was established by using this vector, to illustrate that the tooth surface of the traditional face gear could be considered as developable ruled surface constituted by space lines family, the position vectors of the developable ruled surface were established respectively based on involute, rack and considering the spatial position relationship in meshing. Elaboration and proposition of the principle and method that were used to generate the face gear with the developable ruled surface by straight edged cutter in line contact, and representation of the generated surface model. Furthermore the developable ruled surface was compared to the traditional surface, the normal difference between the two kinds of surfaces is on micro-scale. Numerical examples shows that the normal distance is no more than 1/70 of modulus, the developable ruled surface to which was performed simple longitudinal crowning is able to mesh with the involute surface of the pinion correctly, and demonstrates acceptable geometric meshing performance.

Solution Behavior in the Vicinity of Characteristic Envelopes for the Double Slip and Rotation Model

The boundary conditions significantly affect solution behavior near rough interfaces. This paper presents general asymptotic analysis of solutions for the rigid plastic double slip and rotation model in the vicinity of an envelope of characteristics under plane strain and axially symmetric conditions. This model is used in the mechanics of granular materials. The analysis has important implications for solving boundary value problems because the envelope of characteristics is a natural boundary of the analytic solution. Moreover, an envelope of characteristics often coincides with frictional interfaces. In this case, the regime of sticking is not possible independently of the friction law chosen. It is shown that the solution is singular in the vicinity of envelopes. In particular, the profile of the velocity component tangential to the envelope is described by the sum of the constant and square root functions of the normal distance to the envelope in its vicinity. As a result, some components of the strain rate tensor approach infinity. This finding might help to develop an efficient numerical method for solving boundary value problems and provide the basis for the interpretation of some experimental results.

Crystal structure and Hirshfeld surface analysis of 1,2,4-triazolium hydrogen oxalate

The asymmetric unit of the title 1:1 salt 1,2,4-triazolium hydrogen oxalate, C2H4N3 +·C2HO4 − (I), comprises one 1,2,4-triazolium cation and one hydrogen oxalate anion. In the crystal, the hydrogen oxalate anions are linked by O—H...O hydrogen bonds into chains running parallel to [100]. In turn, the anionic chains are linked through the 1,2,4-triazolium cations by charge-assisted +N—H...O− hydrogen bonds into sheets aligned parallel to (01\overline{1}). The sheets are further stacked through π–π interactions between the 1,2,4-triazolium rings [centroid-to-centroid distance = 3.642 (3) Å, normal distance = 3.225 (3) Å, slippage 1.691 Å], resulting in the formation of a three-dimensional supramolecular network. Hirshfeld surface analysis of the title salt suggests that the most significant contributions to the crystal packing are by H...O/O...H and H...N/N...H contacts involving the hydrogen bonds.

APLIKASI AUGMENTED REALITY (AR) SEBAGAI MEDIA EDUKASI PENGENALAN BENTUK DAN BAGIAN PESAWAT BERBASIS ANDROID

- Augmented Reality is a merger between two worlds, namely the virtual world to the real world, in other words, we can display objects in the virtual world into the real world. Augmented Reality has many opportunities to continue to be developed in any field. The Augmented Reality method also has the advantage of an interactive side because the makers to display certain videos that are directed to the webcam. Making an interactive learning media application using augmented reality technology will be applied to Android-based smartphones and is designed as a learning medium for cadets and prospective cadets of ATKP Medan to the general public. In this application, there are 3D objects in the shape of the plane and its parts created using the 3Dsmax and Blender applications, with Unity as the game engine and Vuforia as the library. The way to use it is by pointing the smartphone camera at the markers that have been provided. Then on the smartphone screen, an object will appear 3D aircraft and the inside. The making of this application will help increase the understanding and participation of the general public as well as the Medan ATKP cadets in learning to recognize the shapes and parts of the aircraft. The results of testing the introduction of an aircraft application can run on a variety of Android mobile devices. The normal distance that can be detected by the camera is 6cm to 4m with a marker size of 20 x 22cm. The slope that can be detected normally between 20 ͦ - 90 ͦ. Based on the percentage of markers that are blocked can run between 0-87%. Based on the results of the questionnaire, the material contained in the aircraft form and part recognition application using Android-based Augmented Reality is suitable for introducing aircraft shapes and parts to field ATKP cadets to the general public. There are still many shortcomings that can be developed, such as increasing 3D plane objects and making better animations, so that applications are more interesting, interactive, and easy to understand.Keywords - Augmented Reality, Android, Unity, Vuforia, 3D, Blender Abstract - Augmented Reality merupakan penggabungan antara dua dunia, yaitu dunia maya ke dunia nyata, dalam kata lain benda dalam dunia maya dapat kita tampilkan ke dunia nyata. Augmented Reality memiliki banyak peluang untuk terus dikembangkan dalam bidang apapun. Metode Augmented Reality juga memiliki kelebihan dari sisi interaktif karena pembuat untuk menampilkan video tertentu yang diarahkan ke webcam. Pembuatan aplikasi media pembelajaran interaktif menggunakan teknologi augmented reality ini akan diterapkan pada smartphone berbasis Android dan didesain sebagai media pembelajaran bagi taruna maupun calon taruna ATKP Medan hingga masyarakat umum. Di dalam aplikasi ini terdapat objek 3D bentuk pesawat dan bagian-bagiannya yang dibuat dengan menggunakan aplikasi 3Dsmax dan Blender, dengan Unity sebagai game engine dan Vuforia sebagai library. Cara penggunaanya adalah dengan mengarahkan kamera smartphone pada marker atau penanda yang telah tersedia. Kemudian dilayar smartphone akan muncul objek 3D Pesawat serta bagian sisi dalamnya. Pembuatan aplikasi ini akan membantu meningkatkan pemahaman dan partisipasi masyarakat umum maupun taruna ATKP Medan dalam belajar mengenal bentuk dan bagian dalam pesawat. Hasil dari pengujian aplikasi Pengenalan pesawat terbang dapat berjalan pada berbagai perangkat mobile Android. Jarak normal yang dapat terdeteksi oleh kamera adalah 6cm sampai 4m dengan ukuran marker 20 x 22cm. Kemiringan yang dapat terdeteksi dengan normal antara 20 ͦ - 90 ͦ. Berdasarkan prosentase marker yang terhalang dapat berjalan antara 0-87%. Berdasarkan hasil kuesioner materi yang terdapat pada aplikasi pengenalan bentuk dan bagian pesawat menggunakan Augmented Reality berbasis android ini cocok untuk mengenalkan bentuk dan bagian pesawat kepada taruna ATKP medan hingga masyarakat umum. Masih banyak kekurangan yang dapat dikembangkan, misalnya memperbanyak objek 3D pesawat dan membuat animasi yang lebih baik, agar aplikasi lebih menarik, interaktif, dan mudah dipahami. Kata kunci - Augmented Reality, Android, Unity, Vuforia, 3D, Blender

Higher Dimensional Data Access and Management with Improved Distance Metric Access for Higher Dimensional Non-Linear Data

Distance metrics for different kinds of data we daily use is the common approach for indentifying the insights of information and identifying the noisy and resolving the information with different scenarios and rules. The methodology imposed here is different in kinds of rules and the information we provide to the knowledge machine is the most important and considerable thing in designing and implementing distance metrics. The contradictory data is mixed information which the dataset includes is having the irrelevant information with the relevant information and identifying the novel thing from the information gathered. The information and the data gathered will be in the form of different formats of data and the most frequent thing we use is to make the clusters. In this article machine learning applications and the different data mining distance metric algorithms will be discussed and the information passed to the machine will be the ultimate and the dataset making is the quite challenging. In machine learning implementation the path of identifying the concept behind the everything to be predicted. The prediction works when the data is accurate and the information we get from the different repositories. All the data captured is not genuine and the combination of different such kind repositories make the contradicting data. The usage the additional distance metrics to manipulate and calculate the relation between the variables or the features we are considering. The machine learning is the finite mechanism which can help the researchers to identify the relationships between the variables or there is chance to find the inner relations among this kind of contradictory information. Contradictory data can help to identify the inner relations which can’t be identified with normal distance metrics and here used a little advanced and succeeded in reaching the optimal result.

Validation of a Model for Estimating the Strength of a Vortex Created from the Bound Circulation of a Vortex Generator

A hypothesis was tested and validated for predicting the vortex strength induced by a vortex generator in wall-bounded flow by combining the knowledge of the Vortex Generator (VG) geometry and the approaching boundary layer velocity distribution. In this paper, the spanwise distribution of bound circulation on a vortex generator was computed by integrating the pressure force along the VG height, calculated using Computational Fluid Dynamics (CFD). It was then assumed that all this bound circulation was shed into a wake to fulfill Helmholtz’s theorem which then curls up into one primary tip vortex. To validate this, the trailed circulation estimated from the distribution of the bound circulation was compared to the one in the wake behind the vortex generator, determined directly from the wake velocities at some downstream distance. In practical situations, the pressure distribution on a vane is unknown and consequently other estimates of the spanwise force distribution on a VG must instead be applied, such as using 2D airfoil data corresponding to the VG geometry at each wall-normal distance. Such models have previously been proposed and used as an engineering tool to aid preliminary VG design. Therefore, it is not the purpose of this paper to refine such engineering models, but rather to validate their assumptions, such as applying a lifting line model on a VG that has a very low aspect ratio and is placed in a wall boundary layer. Herein, high Reynolds number boundary layer measurements of VG-induced flow were used to validate the Reynolds-Averaged Navier–Stokes (RANS) model circulation results, which were used for further illustration and validation of the hypothesis.