Synchronous steady state response of an overhung rotor with squeeze film damping

An analytical method is developed for treatment of a typical system in which the outrigger bearing of an overhung rotor is provided with a squeeze film damper supported in a flexible casing. The rotor and stator of multiple degrees-of-freedom are handled with convenience by a “polar receptance matrix” method. A characteristic equation is derived which governs rotor-stator interaction either with dry contact or through a squeeze film damper. For the nonlinear squeeze film action solutions based on “mobility” information of a dynamically loaded journal bearing are obtained facilitating a general approach. A computer programme is written in Fortran for steady state response of the system in terms of whirl, position and force vectors, trial runs of which indicate complex behaviour of a squeeze film damped system.     

Oscillatory flow in a stratified medium past an infinite porous plate with constant suction

An approximate solution to oscillatory flow past a porous horizontal plate was carried out under the following conditions

• (i) Constant suction
• (ii) Stratification of the medium due to change in density, viscosity and thermal conductivity
• (iii) Free-stream oscillation about a nonzero constant mean.

Solutions have been derived for the transient velocity, the transient temperature, the amplitude and the phase of skin friction and the amplitude and phase of the first and second harmonics of the rate of heat transfer. These are shown on the graphs. The effects of the suction parameter S, the stratification parameter λ, the frequency λ and the Eckert number E are discussed.     

Streamflow Modeling in a Highly Managed Mountainous Glacier Watershed Using SWAT: The Upper Rhone River Watershed Case in Switzerland

Streamflow simulation is often challenging in mountainous watersheds because of irregular topography and complex hydrological processes. Rates of change in precipitation and temperature with respect to elevation often limit the ability to reproduce stream runoff by hydrological models. Anthropogenic influence, such as water transfers in high altitude hydropower reservoirs increases the difficulty in modeling since the natural flow regime is altered by long term storage of water in the reservoirs. The Soil and Water Assessment Tool (SWAT) was used for simulating streamflow in the upper Rhone watershed located in the south western part of Switzerland. The catchment area covers 5220 km², where most of the land cover is dominated by forest and 14 % is glacier. Streamflow calibration was done at daily time steps for the period of 2001–2005, and validated for 2006–2010. Two different approaches were used for simulating snow and glacier melt process, namely the temperature index approach with and without elevation bands. The hydropower network was implemented based on the intake points that form part of the inter-reservoir network. Subbasins were grouped into two major categories with glaciers and without glaciers for simulating snow and glacier melt processes. Model performance was evaluated both visually and statistically where a good relation between observed and simulated discharge was found. Our study suggests that a proper configuration of the network leads to better model performance despite the complexity that arises for water transaction. Implementing elevation bands generates better results than without elevation bands. Results show that considering all the complexity arising from natural variability and anthropogenic influences, SWAT performs well in simulating runoff in the upper Rhone watershed. Findings from this study can be applicable for high elevation snow and glacier dominated catchments with similar hydro-physiographic constraints.     

Fake news detection system based on modified bi-directional long short term memory

Multimedia Tools and Applications - The use of social media has increased tremendously during the past few decades and is considered one of the major sources of news. Social media don’t have...     

Synthetic Base Stock Based on Guerbet Alcohols

Guerbet (β branched) alcohols of varying chain length of even carbon numbers were synthesized by using single linear fatty alcohols ranging from 1-octanol to 1-dodecanol. All Guerbet alcohols having fewer than 28 carbon atoms and are liquid at 0 °C due to β branching. Synthetic base oils were prepared by reacting commonly available unsaturated fatty acids and dicarboxylic acids with Guerbet alcohols using p-toluenesulfonic acid as a catalyst. These base oils were characterized by physical and tribological properties like viscosity, viscosity index, pour point, flash point, wear scar, weld load, coefficient of friction etc. and compared with commercially available 150 and 500 N base oils.     

卷取温度对Q960热轧薄钢板组织与性能的影响

研究了中低温卷取温度对Q960热轧薄板钢显微组织和力学性能的影响。结果表明,随着卷取温度从562℃降至359℃,Q960热轧板的显微组织由粒状贝氏体+少量的珠光体转变为下贝氏体;渗碳体含量明显增加而MC相略有下降。低温或超低温卷取可以减轻或消除Q960热轧板的带状组织。采用非再结晶轧制和约350℃低温卷取可以使Q960热轧卷板获得1000 MPa以上的非比例延伸强度,同时冲击性能良好。     

Bioactive Constituents Present in Garcinia Indica Choisy and its Potential Food Applications: A Review

Kokum (Garcinia indica Choisy), a tropical fruit, is a potential source of anthocyanin, which has a great potential as a natural colorant. The major acid present in it is hydroxy citric acid, which is used as an antiobesity ingredient in pharmaceutical industries. The fruit also contains garcinol, a polyisoprenylated benzophenone derivative, which is an antioxidant and has a chelating activity. It is used in making health beverages or squash and jellies like products. The review highlights the bioactive constituents present in kokum fruit and also discusses the extraction, purification and concentration of anthocyanins from kokum and its applications in foods.     

Numerical Study of Frequency and Deflection Responses of Natural Fiber (Luffa) Reinforced Polymer Composite and Experimental Validation

ABSTRACT

The natural fiber (Luffa cylindrica fiber) reinforced epoxy composite has been fabricated and their structural responses (frequency and deflection) have been computed experimentally and numerically first time using the corresponding experimental elastic properties. The numerical responses are obtained with the help of an in-house MATLAB code developed based on the higher order finite element (FE) model. The completeness of the model has been examined by comparing the current FE solutions (frequency and the central deflection) with the reference as well as in-house experimental data. The effect of fiber volume fractions on the elastic properties is verified for four different weight percentage of treated Luffa fiber (0%, 3.2%, 6.4%, and 9.6%). Finally, the inclusive behavior of the current higher order FE model and the corresponding influence of the significant design parameter of Luffa fiber-reinforced composite structure have been debated by solving different numerical examples.     

Catalytic HTL-derived biochar and sol-gel synthesized (Mn,Ti)-oxides for asymmetric supercapacitors

In this study, hydrothermal liquefaction (HTL)-derived biochar is investigated as electrode material with sol-gel-derived (Mn, Ti)-oxide electrode for asymmetric supercapacitor. To generate biochar, pinewood flour was used as an example biomass feedstock for HTL, which was carried out at 300°C and 1500 psi for 1 hour in the absence and presence of the Ni-nitrate (Ni[NO₃]₂.6H₂O) catalyst. After HTL, different products were analyzed by TOC analyzer, HPLC, and GCMS, and mass yield/carbon balance was determined. Solid residue recovered after HTL or catalytic HTL (CHTL) was thermally treated at 400°C for 2 hours to obtain biochar, which was characterized using BET surface area analyzer and SEM/EDX, and utilized as one of the electrodes. To fabricate asymmetric supercapacitor (ASC), (Mn,Ti)-oxide electrode material was synthesized using sol-gel technique with Mn:Ti precursor ratio of 30:70 wt%. As-synthesized gels were aged, dried, and calcined with a 2-step heating process (step-1: heating to 500°C and cooling to 50°C, and step-2: heating to 1000°C with soak time of 2 hours and cooling to 50°C), which were characterized by powdered X-ray diffraction and BET analysis. Asymmetric supercapacitors were fabricated with HTL/CHTL derived biochar/(Mn,Ti)-oxide electrodes and KOH electrolyte, and tested with cyclic voltammetry to determine specific capacitance. ASC fabricated with CHTL-derived biochar electrode showed a higher specific capacitance of 187 F/g.