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.

Innovative Monitoring Techniques for Wadi Flash Flood by Using Image-Based Analysis

Flash floods in wadi systems are a very important environmental issue, and their monitoring is necessary for many applications, including water resource management, irrigation and flood control. However, monitoring networks are very rare and lack spatial distribution features. In this study, image-based techniques were used to quantify and monitor flash floods in wadi channels by using two different methods. In the first section, we employed photogrammetry processing technique to quantify post-peak flood discharges by using a drone survey to build a digital elevation model (DEM) with a high resolution and calibrated and validated the model with a field survey (levelling measurements). This technique used drone-collected images to construct a DEM for extracting a cross-sectional profile and elevation points to calculate the peak discharge using the slope-area method with the Manning equation. In the second section, we combined the previous technique with the large-scale particle image velocimetry (LSPIV) technique to measure flash flood discharge by installing a fixed camera on a road bridge crossing a wadi channel and using a digitally extracted cross section from the DEM in the analysis. The results of those techniques show a high efficiency that is equivalent to that of conventional methods.

Quasi-zero stiffness isolator based on bistable structures with variable cross-section

Simple and light-weighted quasi-zero stiffness (QZS) isolators can be designed based on nonlinear and negative stiffness generated by the snap-through effect of bistable structures. Traditionally, the snap-through force of the bistable structure is limited which makes the weight which can be isolated based on this mechanism very low. This paper investigates increasing loading capacity of this kind of isolator by using an optimized and varying sectional profile. Numerical models were derived for the bistable structures with variable sectional distributions. Optimized sections’ alignment of the bistable beam was derived based on the numerical model which was consequently validated by experimental results. Influences of the bistable beams with a variable section on nonlinear stiffness characteristics and performance of the isolator were at last investigated with the harmonic balance method.

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

On adequacy of parameters of strip cross-section profile. Part 1. Predictive interval

Increasing the level of automation of metallurgical units and the development of industrial information systems increases the number of p ters of production and technological processes available for analysis. The consequence is an increase in the complexity and duration of preliminary data preparation for subsequent mathematical and statistical analysis. It is therefore important to develop new and improve existing techniques for the automated process of primary data production. When developing methods of primary data preparation, it should be taken into account that accuracy and adequacy of results of subsequent mathematical analysis are determined by accuracy and adequacy of used initial data. The cross-sectional profile parameters of hot-rolled strips, such as wedge, convexity, thickness variation, displacement, wedge in near-rim zones, local thickenings and thinning of the strip are calculated parameters, i.e. secondary to actual strip thickness measurements over the length and width of hot-rolled strips. As technology is improved in cold rolling shops, the number of grade groups is increasing, for which technological modes of units and processing routes are selected. They are based on actual values of parameters of cross-section profile in order to further reduce the probability of formation of inappropriate products and increased metal consumption. The presented article provides an overview of conventional calculation methods for parameters of cross-section profile of hot-rolled strip and gives an assessment of accuracy and adequacy of application of the parameters averaged along strip length to the whole strip.

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.