Preparation of a Nickel Layer with Bell-Mouthed Macropores via the Dual-Template Method

A relatively static and unique bubble template is successfully realized on a microporous substrate by controlling the surface tensions of the electrodeposit solution, and a nickel layer containing macropores is prepared using this bubble template. When the surface tension of the solution is 50.2 mN/m, the desired bubble template can be formed, there are fewer bubbles attached to other areas on the substrate, and a good nickel layer is obtained. In the analysis of the macropore formation process, it is found that the size of the bell-mouthed macropores can be tailored by changing the solution stirring speed or the current density to adjust the growth rate of the bubble template. The size change of a macropore is measured by the profile angle of the longitudinal macropore, section. As the solution stirring speed increases from 160 to 480 r/min, the angle range of the bell-mouthed macropores cross-sectional profile is increased from 21.0° to 44.3°. In addition, the angle range of the bell-mouthed macropore cross-sectional profile is increased from 39.3° to 46.3° with the current density increasing from 1 to 2.5 A/dm2. Different from the dynamic hydrogen bubble template, the bubble template implemented in this paper stays attached on the deposition and grows slowly, which is novel and interesting, and the nickel layer containing macropores prepared using this bubble template is applied in completely different fields.

Evaluasi Perencanaan Jembatan Kereta Api Rangka Baja Double Track Tipe Welded Through Truss Bentang 50 meter

ABSTRAKPenelitian ini menganalisis perencanaan struktur atas jembatan kereta api rangka baja double track tipe Welded Through Truss (WTT) dengan bentang jembatan 50 m melalui Gambar Standar Tipikal Jembatan yang ada di lapangan. Analisis dan pembebanan jembatan sesuai kriteria teknis yang mengacu pada Lampiran Peraturan Menteri Perhubungan No. 60 Tahun 2012 tentang Persyaratan Teknis Jalur Kereta Api. Hasilnya dievaluasi dalam nilai tegangan dan defleksi. Hasil analisis menunjukan bahwa terdapat beberapa batang diagonal yang menghasilkan angka rasio tegangan > 1, sehingga perlu dilakukan penambahan tebal profil penampang atau juga menambahkan stiffener pada elemen-elemen jembatan yang kritis. Namun demikian nilai lendutan aktual di tengah bentang sebesar 46,651 mm masih memenuhi syarat karena kurang dari lendutan ijin 50 mm.Kata kunci: jembatan kereta api, welded through truss, PM 60 Tahun 2012, rasio tegangan dan defleksi ABSTRACTThis study analyzed the performance design about the uper structure of typical railway bridge for the 50 m WTT (Welded Through Truss) steel frame railway bridge with double track. Planning criteria refer to Attachment to the Minister of Transportation Regulation No. 60 of 2012 for Technical Requirements for Railroad. The results are evaluated in terms of stress ratio and deflection. The analysis result show that the 50 m WTT (Welded Through Truss) steel frame railway bridge has several diagonal bars that produce a stress ratio > 1, so it is necessary to add the thickness of the cross sectional profile or also to add a stiffener to the bridge structure. However the actual deflection value in the middle of the span of 46.651 mm still meets the requirements because it is less than the allowable deflection of 50 mm.Keywords: railway bridge, welded through truss, PM 60 of 2012, stress ratio and deflection

Bonding widths of Deposited Polymer Strands in Additive Manufacturing

In this study, we explore the deformation of a polymer extrudate upon the deposition on a build platform, to determine the bonding widths between stacked strands in fused-filament fabrication. The considered polymer melt has an extremely high viscosity, which dominates in its deformation. Mainly considering the viscous effect, we derive analytical expressions of the flat width, compressed depth, bonding width and cross-sectional profile of the filament in four special cases, which have different combinations of extrusion speed, print speed and nozzle height. We further validate the derived relations, using our experimental results on acrylonitrile butadiene styrene (ABS), as well as existing experimental and numerical results on ABS and polylactic acid (PLA). Compared with existing theoretical and numerical results, our derived analytic relations are simple, which need less calculations. They can be used to quickly predict the geometries of the deposited strands, including the bonding widths.

A Numerical Swallowing-Capacity Analysis of a Vacant, Cylindrical, Bi-Directional Tidal Turbine Duct in Aligned & Yawed Flow Conditions

Introducing a duct along the perimeter of a rotor has been acknowledged to augment turbine performance. The outcome causation due to a bi-directional, cylindrical shroud, however, is uncertain. This study analyses the hydrodynamic swallowing capacity of a true-scale, vacant duct for tidal turbine applications in aligned and yawed inlet flow conditions by utilising three-dimensional unsteady computational fluid dynamics. The performance is investigated within free-stream magnitudes of 1 to 7 m.s−1, and a bearing angular range of 0° to 45° with the duct axis. In proportion to the free-stream magnitude, the normalised axial velocity through the duct increases as a result of a diminishment in pressure drag. Within yawed flow, the maximum capacity falls at a bearing of 23.2°, resulting in a performance increase of 4.13% above that at aligned flow conditions. The analysis concludes that the augmentation at yawed flow occurs due to the duct cross-sectional profile lift variation with angle-of-attack. Towards nominal yaw angle, the internal static pressure reduces, permitting a higher mass-flow rate. Beyond the nominal angle-of-attack, flow separation occurs within the duct, increasing pressure drag, thereby reducing the swallowing capacity.

Hydromechanics, Aerodynamics and Thermodynamics: Critical Numerical Analysis of Aerodynamics of BLE Turbine Blade

This contribution presents a numerical analysis based on the effects of aerodynamics of the bump-based humpback whale fins available on the turbine blade edge. In this research, performance comparisons have been made based on dual sequestered blades. One of the blades was sinusoidal in shaped with Bumped Lead Edge (BLE) and the other one with Upright Leading Edge (ULE). However, all the blades are based on a similar cross-sectional profile i.e. NACA-012. This research has been based on simulations of Reynold’s number i.e. 1.8.105 of Attack Angle (AA) i.e. from ‘0º - 30º’. At this angle, especially greater than 10º, the BLE has indicated an enhancement in about 3.5% to 9.0% lift and a reducing drag whereas the negligible variation in lifts and minor drag is displayed for AA less than 10º. The findings in this result for BLE have indicated a substantial achievement in aerodynamic features for particular AA.

Fault Analysis for Reliability Centered Maintenance (RCM) in Machining

This contribution presents a numerical analysis based on the effects of aerodynamics of the bump-based humpback whale fins available on the turbine blade edge. In this research, performance comparisons have been made based on dual sequestered blades. One of the blades was sinusoidal in shaped with Bumped Lead Edge (BLE) and the other one with Upright Leading Edge (ULE). However, all the blades are based on a similar cross-sectional profile i.e. NACA-012. This research has been based on simulations of Reynold’s number i.e. 1.8.105 of Attack Angle (AA) i.e. from ‘0º - 30º’. At this angle, especially greater than 10º, the BLE has indicated an enhancement in about 3.5% to 9.0% lift and a reducing drag whereas the negligible variation in lifts and minor drag is displayed for AA less than 10º. The findings in this result for BLE have indicated a substantial achievement in aerodynamic features for particular AA.

Assessment of the actual shape of the hot-rolled strip cross-section contour. Part 2. Profile Classifier

The geometric parameters describing the features of the crosssectional profile of a hot-rolled strips do not give a complete picture of the flatness acquired by the cold-rolled strips rolled from these strips. An additional analysis, the results of which are presented in Message 1, showed that there are four characteristic classes of cross-sectional profiles of hot rolled strips that have a significant effect on the shape of the strips during cold rolling, three of which negatively affect the flatness of the cold rolled strips. The cross-sectional profiles of hot-rolled strips with a concave middle part and / or marginal thickenings lead to the appearance of edge waviness, peak-like cross-sectional profiles cause central warping. Therefore, the actual task is to determine the factual shape of cross-sectional profile. 6th order polynomials were used to digitalize and parameterize hot-rolled profile. As a result, we developed analytic function of the transverse profile, which keeps important information about its near-edge areas and features in the middle part. To assign a specific crosssectional profile of a hot-rolled strip to one of four characteristic classes of cross-sections, mathematical software was developed, called a classifier, and implemented with the programming environment R. To classify the profiles of the hot-rolled cross-section according to characteristic classes, a linear discriminant method was used as a machine learning method analysis. The result is an adequate mathematical model for recognizing the shape of the cross-sectional profile. The study was carried out with the financial support of the Russian Foundation for Basic Research within the framework of scientific project No. 19-38-90257.