Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and power cone programming

In the present study, the stability of a vertical rock escarpment is determined by considering the influence of undercut. Lower bound finite element limit analysis in association with Power Cone Programming (PCP) is applied to incorporate the failure of rock mass with the help of the Generalized Hoek-Brown yield criterion. The change in stability due to the presence of undercut is expressed in terms of a non-dimensional stability number (σ_ci/γH). The variations of the magnitude of σ_ci/γH are presented as design charts by considering the different magnitudes of undercut offset (H/v_u and w_u/v_u) from the vertical edge and different magnitudes of Hoek-Brown rock mass strength parameters (Geological Strength Index (GSI), rock parameter (m_i,), Disturbance factor (D)). The obtained results indicate that undercut can cause a severe stability problem in rock mass having poor strength. With the help of regression analysis of the computed results, a simplified design equation is proposed for obtaining σ_ci/γH. By performing sensitivity analysis for an undisturbed vertical rock escarpment, we have found that the undercut height ratio (H/v_u) is the most sensitive parameter followed by GSI, undercut shape ratio (w_u/v_u), and m_i. The developed design equation as well as design charts can be useful for practicing engineers to determine the stability of the vertical rock escarpment in the presence of undercut. Failure patterns are also presented to understand type of failure and extent of plastic state during collapse.     

Electrical and dielectric properties of TiO2 and Fe2O3 doped fly ash

Electrical properties of ceramic materials has become an area of increasing interest in research because these materials possess a great potential for solid-state devices. Conducting polymer composites have attracted considerable interest in recent years because of their numerous applications in a variety of electric and electronic devices. It has been observed that these materials possess a very high relative dielectric constant and high electrical properties at room temperature. Such a high dielectric constant is one of the important parameters in capacitor fabrication and a high electrical conductivity can be used for ionic batteries and electrochemical sensors.     

Annealing characteristics of hot carrier induced damage in n-channel MOSFETs

The recovery process of hot carrier induced degraded device parameters in n-channel MOSFETs has been analysed by both isothermal and isochronal annealing. A wide distribution of activation energies of hot carrier induced damage, with a peak at around 0·9eV is observed. It can be seen that isochronal annealing has advantages over isothermal annealing in recovering the degraded device characteristics in comparatively less time. Bias annealing of the device reveals that initially the annealing of trapped oxide charges increases the interface state density, after reaching the peak value interface states anneal as a logarithmic function of time. The energy distribution of hot carrier induced interface states is similar to radiation induced interface states after a few hours of annealing at room temperature.     

REACTIVE POWER COMPENSATION FOR INDUSTRIAL CONSUMERS: A NEW APPROACH

ABSTRACT

In this paper an attempt is made to obtain optimum reactive power compensation of industrial consumers by minimizing an objective function which is based on power loss saving, energy saving, maximum KVA demand saving and capacitor capacity requiements. It is also shown that how utilities as well as industrial consumers will be benefitted due to reactive power compensation.     

Improvement of Plasma Performance with Lithium Wall Conditioning in Aditya Tokamak

Lithiumization of the vacuum vessel wall of the Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done to understand its effect on plasma performance. After the Li-coating, an increment of ～100 eV in plasma electron temperature has been observed in most of the discharges compared to discharges without Li coating, and the shot reproducibility is considerably improved. Detailed studies of impurity behaviour and hydrogen recycling are made in the Li coated discharges by observing spectral lines of hydrogen, carbon, and oxygen in the visible region using optical fiber, an interference filter, and PMT based systems. A large reduction in O I signal (up to ～ 40% to 50%) and a 20% to 30% decrease of H α signal indicate significant reduction of wall recycling. Furthermore, VUV emissions from O V and Fe XV monitored by a grazing incidence monochromator also show the reduction. Lower Fe XV emission indicates the declined impurity penetration to the core plasma in the Li coated discharges. Significant increase of the particle and energy confinement times and the reduction of Z eff of the plasma certainly indicate the improved plasma parameters in the Aditya tokamak after lithium wall conditioning.     

添加Al-TiB中间合金对铝合金组织、磨损和压缩变形行为的影响(英文)

在7178铝合金中添加不同比例的Al-10%TiB中间合金,考察TiB对铝合金的晶粒细化、磨损和压缩变形行为的影响。组织观察表明,TiB颗粒起着晶粒细化剂的作用,导致生成球状枝晶。当Al-TiB中间合金的添加量超过20%时,合金的耐磨性和强度随着中间合金添加量的增加而降低,即使其枝晶组织变得更细而接近于球状组织。     

Synthesis and characterization of lanthanide-doped sodium holmium fluoride nanoparticles for potential application in photothermal therapy

Upconversion nanoparticles (UC NPs) in combination with plasmonic materials have great potential for cancer photothermal therapy. Recently, sodium holmium fluoride (NaHoF₄) is being investigated for luminescence and magnetic resonance imaging (MRI) contrast agent. Here, we present successful synthesis of excellent quality doped NaHoF₄ NPs for possible UC luminescence application and coated for possible photothermal therapy application. Synthesized NaHoF₄ nanocrystals were doped with Yb/Er and coated with gold, gold/silica, silver and polypyrrole (PPy). XRD, XPS and TEM were used to determine structure and morphology of the NPs. Strong UC photoluminescence (PL) emission spectra were obtained from the NPs when excited by near-infrared (NIR) light at 980 nm. Cell viability and toxicity of the NPs were characterized using pancreatic and ovarian cancer cells with results showing that gold/silica coating produced least toxicity followed by gold coating.     

OCSO-CA: opposition based competitive swarm optimizer in energy efficient IoT clustering

With the advent of modern technologies,IoT has become an alluring field of research.Since IoT connects everything to the network and transmits big data frequently,it can face issues regarding a large amount of energy loss.In this respect,this paper mainly focuses on reducing the energy loss problem and designing an energy-efficient data transfer scenario between IoT devices and clouds.Consequently,a layered architectural framework for IoT-cloud transmission has been proposed that endorses the improvement in energy efficiency,network lifetime and latency.Furthermore,an Opposition based Competitive Swarm Optimizer oriented clustering approach named OCSO-CA has been proposed to get the optimal set of clusters in the IoT device network.The proposed strategy will help in managing intra-cluster and inter-cluster data communications in an energy-efficient way.Also,a comparative analysis of the proposed approach with the state-of-the-art optimization algorithms for clustering has been performed.