Studi Numerik Perbandingan Kinerja dan Medan Aliran Turbin Vortex Gravitasi dengan Tipe Sudu Lengkung Backward dan Forward

<p><em>The interaction of turbine blades with vortex flow in micro-hydro power plants based on gravity vortex is still not clearly clarified, therefore numerical simulation is a tool to produce flow visualization that helps analyze the performance of experimental results. This study aims to compare the performance of a gravity vortex flow power generator using a conical basin with a </em><em>inclined</em><em> backward and </em><em>inclined </em><em>forward blade design using a numerical simulation approach. The simulation begins by validating the results of torque performance and visualizing the flow of experimental research conducted by previous researchers, then the simulation settings are used to compare the performance of the </em><em>inclined</em><em> backward and </em><em>inclined </em><em>forward blade turbine designs with variations in turbine rotation speed of 80, 120, 160 and 180 rpm. The simulation results show that the curved backward blade performance is better than the forward curved blade which is supported by visualizing the free surface flow and static pressure contours on the blade surface.</em><em></em></p>

Description of Basilaphelenchus pedrami n. sp. (Tylenchomorpha: Aphelenchoididae) isolated from Kyoto, Japan

Summary An undescribed Basilaphelenchus species was isolated from the dead and decaying wood of an unidentified broad-leaved tree in Kyoto, Japan. The species was cultured on a lawn of Botrytis cinerea after many attempts and kept as a laboratory strain. The nematode is characterised by the position of its secretory-excretory pore, which differs between males (anterior to median bulb) and females (overlapping or posterior to median bulb), the tail morphology of males (conical with very short mucron) and females (smoothly tapering conical with various shapes at terminus) and male spicule morphology, with spicules possessing a smoothly curved blade (calomus-lamina complex) and a shallow capitulum depression. In addition, the new species is differentiated from other members of the genus by the molecular sequences of its ribosomal RNA region. Phylogenetically, the new species is close to two Iranian species, B. brevicaudatus and B. gorganensis, but can be distinguished from them based upon its separated phylogenetic status. The genus contains five species that were described from Chile and Iran. Thus, the isolation of a species from this genus in Kyoto, Japan, represents the first record of the genus from East Asia. The new species is described and illustrated herein as B. pedrami n. sp.

Morphological Analysis of the Bone Serrated Points from Early Neolithic Complexes of Shamanka 2 Burial Ground

An analysis of the bone serrated points from the burial complexes of Shamanka 2 burial ground is presented. The origin of the collection makes it “ritual”, which may explain the large number of undamaged items. Several spikes have been broken intentionally at the time of their interment. Supposedly, several points have been specifically made for interment. In accordance with the morphological analysis, we have identified two groups of serrated spikes: (I) detachable tools and (II) non-detachable tools. Differences in structural elements of the stopper-line determine 7 types of harpoons (95 items), and variations in base structure define 2 types of points of leisters, javelins, spears etc. (6 items), while 15 fragments of blade were excluded from the analysis. Harpoons of the Type I-1 and Type I-2 are divided into 9 varieties, in accordance with structural elements of the blade. Harpoons of the Type I-3 are divided into 2 subtypes due to differences in structural elements of the shaft. Harpoons of the I-4 – I-7 types are represented by only 1 item for each type and are considered to be individual tools. Group I (harpoons) consist mostly of tools with an orifice for line lashing (89 items). Harpoons that feature stopper-line structural elements without through hole are represented here by only 6 items. II-2 type points with a unilaterally beveled base represent most non-detachable barbed tools – 5 items. II-1 type points with a wedgelike base (in a profile) consist of only 1 item. The designated types and varieties of Shamanka II cemetery barbed spikes correlate with items from different synchronous and asynchronous sites of both bordering and substantially remote regions. Serrated points are found mainly in male burials but absent in children's burials. Chronologically, 111 barbed spikes relate to the Phase 1 of the Shamanka 2 cemetery functioning. Five more spikes were recorded in 3 burials of the Phase 2. Barbed spikes of the chronological Phase 2 are represented with 4 items of the I-1.4 variety from burials No. 108-1 and 64-2, as well as 1 item of the I-2-1 variety from a grave No. 49. The last artifact probably represents an ideal model of two-row harpoons with symmetrically situated barbs and a sword-like spike. Harpoons with a curved blade (Type I-1.4) were registered only in burials of the chronological Phase 2. The barbed spikes of the I-1 and I-2 types, which feature a stopper-line with through holes and lateral projections, correlate with a definition of harpoons of the Kitoi type.

The Effects of Curved Blade Turbine on the Hydrodynamic Structure of a Stirred Tank

This work is aimed at studying the hydrodynamic structure in a cylindrical stirred vessel equipped with an eight-curved blade turbine. Flow fields were measured by two-dimensional particle image velocimetry (PIV) to evaluate the effect of the curved blade turbine. Velocity field, axial and radial velocity distribution, root mean square (rms) of the velocity fluctuations, vorticity, and turbulent kinetic energy were presented. Therefore, two recirculation loops were formed close to the free surface and in the bottom of the tank. Moreover, the highest value area of the vorticity is localized in the upper region of the tank which follows the same direction of the first circulation loop. The turbulent kinetic energy is maximum at the blade tip following the trailing vortices.

THEORETICAL STUDY OF THE MATERIAL GRINDING PROCESS IN THE WORKING CHAMBER OF A DISK MILL

This article analyzes the movement of material particles in the central and peripheral parts of the working chamber of a disk mill. A diagram of a disk mill and a diagram of the movement of particles in its working chamber are presented. The cutting elements are blades in the shape of a parabola located on the disks having an inclined surface. An expression is found for determining the time when a particle is located inside the grinding chamber of a mill. It is determined that this time depends on the geometric (x1; y1; x2; y2; ) and technological (ω) parameters. The dependence of the time spent on the change in the angle of deviation of the surface of the curved blade from the radial direction is shown in figure 3. As a result of theoretical research, an analytical expression is obtained that allows to determine the particle size at the output of the grinding chamber. According to the found expression, the final particle size at the output of the grinding chamber depends on such parameters as d0, σ, ω, and . As a result, the dependence (figure 4) of the ratio of the initial particle size to the final one ( 0 ) on the time change is constructed. According to the obtained graphs, as the angle increases, the particle time in the grinding chamber decreases, in result of which the final size of the particle at the output increases.