M- S-H formation in MgO-SiO2slurries via wet milling for magnesia based castables

It is believed that the formation of hydration phase, MgO-SiO₂-H₂O (M-S-H), contributes to good workability and reliable comprehensive properties for magnesia based castables. In order to stimulate the formation of M-S-H in magnesia based castables and understand the minimum introduction of microslica amount, wet milling process was used to promote the dissolution of MgO and SiO₂ in this work. The slurry containing different content of microsilica with wet milling technology and the castables with/without wet milling slurry were prepared. The effects of microsilica content on the formation of hydration phases were analyzed by XRD, FT-IR and TG/DSC and the properties of magnesia based castables were evaluated by explosion resistance, CMOR, HMOR and so on. The results showed that the formation of M-S-H was accelerated because of the dissolution of Mg²⁺ and HSiO₃^? in wet milling process. Higher amount of M-S-H led to a tight bonding in the early stage, and a denser structure after firing at high temperature due to the limited formation of brucite and in-situ formation of evenly distributed forsterite phase. In addition, much higher HMOR were obtained when less microsilica was added, attributing to the suppressed formation of low-melting-point liquid. Therefore, 2–3 wt% microsilica addition was recommended in this process.     

Mixed Convection Heat Transfer from Tandem Square Cylinders in a Vertical Channel at Low Reynolds Numbers

The fluid flow and heat transfer characteristics around two isothermal square cylinders arranged in a tandem configuration with respect to the incoming flow within an insulated vertical channel at low Reynolds number range (1 ≤ Re ≤ 30) are estimated in this article. Spacing between the cylinders (S) is fixed at four widths of the cylinder dimension (d) and, the blockage parameter (B) is set to 0.25. The buoyancy-aided/opposed convection is examined for the Richardson number (Ri) ranges from ?1 to 1 with a fixed Prandtl number (Pr) of 0.7. The transient numerical simulation for this two-dimensional, incompressible, laminar flow and heat transfer problem is carried out by a finite volume code based on the PISO algorithm in a collocated grid system. The results suggest that the flow remains steady for the entire range of parameters chosen in this study. The representative streamlines, vorticity, and isotherm patterns are presented to interpret the flow and thermal transport visualization. Additionally, the time average drag coefficient (C _D ) as well as time and surface average Nusselt number (Nu) for the upstream and downstream cylinders are determined to elucidate the effects of Re and Ri on flow and heat transfer phenomena.     

Experimental Investigation of the Effect of Tube-to-Tube Porous Medium Interconnectors on the Thermohydraulics of Confined Tube Banks

This experimental study investigates the effect of tube-to-tube copper porous interconnectors on the thermohydraulic performance of an in-line and staggered confined tube bank. The porous medium, having a transverse thickness equal to that of the diameter of the tube (9 mm), connects longitudinally six successive tubes kept as in-line and staggered arrangements with a square pitch of 2.0. The tubes are subjected to a constant and uniform heat flux and are cooled by forced convection under laminar-transition flow range (200 < Reynolds number < 1500) using air with a Prandtl number of 0.71 as cooling fluid. Experimental data presented here establish that by introducing tube-to-tube porous medium interconnectors for the maximum Reynolds number tested here, a reduction in the pressure drop by 18% is observed in the in-line configuration while the heat transfer is enhanced by 100% in the staggered configuration, when compared to their respective configurations without the porous medium. Defining an overall energy gain as the ratio of the heat transfer enhancement due to the presence of the porous inserts to the pressure drop incurred, it is seen that fixing the porous inserts in the in-line configuration is advantageous.     

Food insecurity in urban poor households in Mumbai, India

India ranks 66th of 88 countries in the Global Hunger Index and has a quarter of the world??s hungry. Food security status of 377 million inhabitants of India??s urban areas, of which one-fourth live in extreme poverty, is poorly documented. The purpose of this study was to determine (a) the extent of food insecurity among households in urban slums, (b) to quantitatively assess their subjective experiences related to food insecurity and (c) to identify sub-groups among the urban poor that are vulnerable to food insecurity. A cross-sectional, interviewer-administered survey of adult female respondents from 283 households, selected using two-stage cluster sampling, was conducted in slums across three municipal wards in the city of Mumbai. Food insecurity, as measured by the Household Food Insecurity Access Scale (HFIAS), was found in a large number of households in the urban slums of Mumbai; 59.7?% (n?=?169) households were categorized as severely food-insecure, 16.6?% (n?=?47) as mildly to moderately food-insecure, and 23.7?% (n?=?67) as food-secure. Further analysis revealed that severe food insecurity was significantly associated with lower monthly household income and other socioeconomic status measures such as lower household monthly per capita income, lower rank in the standard of living index (SLI) and less monthly per capita expense on food items. Households where the woman was the primary income-earner and contributed the largest share to the monthly household income, and was older, less educated, with less media use or access were more likely to experience severe food insecurity. Although corrective steps at the household level such as livelihood security schemes and income generation programs are necessary, they will not be sufficient to eliminate this problem; state intervention is required in order to assure food security for the urban poor. The Government of India has drafted a Food Security Bill; but the criteria for determining which households are vulnerable and deserving are still being debated. The findings of this study highlight the urgency of corrective action and also provide pointers for the identification of vulnerable or priority sub-groups. Food security policies and programs have to be implemented immediately and effectively in order to ensure that subsidies and food items are allocated to the households of the vulnerable urban poor.     

Nitrites Derived From Foneiculum Vulgare (Fennel) Seeds Promotes Vascular Functions

Abstract: Recent evidence has demonstrated that nitrites play an important role in the cardiovascular system. Fennel (Foneiculum vulgare) seeds are often used as mouth fresheners after a meal in both the Indian sub‐continent and around the world. The present study aims to quantify the nitrite and nitrates in fennel seeds as well as elucidating the effect of fennel derived‐nitrites on vascular functions. Results from our study show that fennel seeds contain significantly higher amount of nitrites when compared to other commonly used post‐meal seeds. Furthermore our study confirmed the functional effects of fennel derived‐nitrites using in vitro and ex vivo models that describe the promotion of angiogenesis, cell migration, and vasorelaxation. We also showed that chewing fennel seeds enhanced nitrite content of saliva. Thus our study indicates the potential role of fennel derived‐nitrites on the vascular system. Practical Application: This study is focused on determining the effect of fennel‐derived nitrites on angiogenesis (the formation of new blood vessels from pre‐existing ones), cell migration, and vasorelaxation (dilation of blood vessels) thereby preserving cardiovascular health.     

Wavelet Bootstrap Multiple Linear Regression Based Hybrid Modeling for Daily River Discharge Forecasting

A new hybrid model, the wavelet–bootstrap–multiple linear regression (WBMLR) is proposed to explore the potential of wavelet analysis and bootstrap resampling techniques for daily discharge forecasting. The performance of the developed WBMLR model is also compared with five more models: multiple linear regression (MLR), artificial neural network (ANN), wavelet-based MLR (WMLR), wavelet-based ANN (WANN) and wavelet–bootstrap–ANN (WBANN) models. Seven years of discharge data from seven gauging stations in the middle reaches of Mahanadi river basin in India are applied in this study. Significant input vectors are decomposed into discrete wavelet components (DWCs) using discrete wavelet transformation (DWT) to generate wavelet sub time series that are used as inputs to the MLR and ANN models to develop the WMLR and WANN models, respectively. Effective wavelets are selected by considering several types of wavelets with different vanishing moments. WBMLR and WBANN models are developed as ensemble of different WMLR and WANN models, respectively, developed using different realizations of the training dataset generated using bootstrap resampling technique. The results show that the wavelet bootstrap hybrid models (i.e. WBMLR and WBANN) produce significantly better results than the traditional MLR and ANN models. Hybrid models based on MLR (WMLR, WBMLR) perform better than the ANN based hybrid models (WBANN, WANN). The WBMLR and WMLR models simulate the peak discharges better than the WBANN, WANN, MLR and ANN models, whereas the overall performance of WBMLR model is found to be more accurate and reliable than the remaining five models.     

Unimportance of geometric nonlinearity in analysis of flanged joints with metal-to-metal contact

Gasketless flanged joints with metal to metal contact offer some advantages over gasketed joints such as lower weight and better fatigue life. Design of such joints is often based on finite element analyses, and complicated by the fact that the area of contact between the flanges changes upon application of loads. Such analyses can be done using commercial software, which can incorporate geometrical nonlinearities as well as contact nonlinearities. Engineering intuition suggests that the role of geometrical nonlinearities might be small for such problems. However, many engineers continue to use the fully nonlinear analyses. Our aim in this paper is simply to put on record that significant savings in time can be obtained by “turning off” geometric nonlinearities in such analyses, with negligible loss of accuracy. To this end, a nonautomated implementation of the basic ideas is first demonstrated for a simple geometry; more automated analyses for a more general geometry follow.     

Lossy magnetic energy storage units for improvement in automatic generation control

Fast-acting energy storage devices can effectively damp electromechanical oscillations in a power system, because they provide storage capacity in addition to kinetic energy of the generator rotor, which can share the sudden changes in power requirement. Earlier studies showed the effectiveness of superconducting magnetic energy storage (SMES) for this purpose. The present paper analyses the characteristics of lossy magnetic energy storage (LMES) and shows the effectiveness of small-sized LMES units in improving power system transient response. Computer studies show that the optimal parameter settings of the power system are changed with the addition of an energy storage element.