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    Wyświetlanie 1-19 z 19
    Tytuł:
    Geotechnical risk classification for underground mines
    Klasyfikacja poziomu zagrożenia geotechnicznego w kopalniach podziemnych
    Autorzy:
    Mishra, R. K.
    Rinne, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/963984.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    underground mining
    geotechnical risk
    risk ranking
    geotechnical hazard potential
    risk assessment
    górnictwo podziemne
    zagrożenia geotechniczne
    ranking poziomu zagrożenia
    ocena potencjalnego ryzyka wystąpienia zagrożeń geotechnicznych
    Opis:
    Underground mining activities are prone to major hazards largely owing to geotechnical reasons. Mining combined with the confined working space and uncertain geotechnical data leads to hazards having the potential of catastrophic consequences. These incidents have the potential of causing multiple fatalities and large financial damages. Use of formal risk assessment in the past has demonstrated an important role in the prediction and prevention of accidents in risk prone industries such as petroleum, nuclear and aviation. This paper proposes a classification system for underground mining operations based on their geotechnical risk levels. The classification is done based on the type of mining method employed and the rock mass in which it is carried out. Mining methods have been classified in groups which offer similar geotechnical risk. The rock mass classification has been proposed based on bulk rock mass properties which are collected as part of the routine mine planning. This classification has been subdivided for various stages of mine planning to suit the extent of available data. Alpha-numeric coding has been proposed to identify a mining operation based on the competency of rock and risk of geotechnical failures. This alpha numeric coding has been further extended to identify mining activity under "Geotechnical Hazard Potential (GHP)". GHP has been proposed to be used as a preliminary tool of risk assessment and risk ranking for a mining activity. The aim of such classification is to be used as a guideline for the justification of a formal geotechnical risk assessment.
    Górnictwo podziemne pociąga za sobą różnorakie zagrożenia spowodowane przez uwarunkowania geotechniczne. Urabianie złoża w połączeniu z pracą w zamkniętej przestrzeni oraz z niepewnymi danymi geotechnicznymi powodować może zagrożenia, które w konsekwencji prowadzić mogą do wypadków, a te potencjalnie powodować mogą skutki śmiertelne dla osób oraz poważne straty finansowe. Wykorzystanie przepisowych metod oceny ryzyka w przeszłości wykazało ich istotną rolę w przewidywaniu i zapobieganiu wypadkom i zagrożeniom w dziedzinach najbardziej na nie narażonych, a więc w przemyśle naftowym, jądrowym oraz w lotnictwie. W niniejszej pracy zaproponowano system klasyfikacji operacji w górnictwie podziemnym w oparciu o poziom zagrożenia geotechnicznego. Klasyfikacji dokonano uwzględniając zastosowaną metodę urabiania oraz rodzaj urabianego górotworu. Przedstawiono kategorie metod urabiania o podobnym poziomie zagrożenia geotechnicznego. Zaproponowano klasyfikację górotworu na podstawie właściwości wytrzymałościowych określanych rutynowo na etapie planowania kopalni. Klasyfikacja ta podzielona jest na kilka pod-etapów odpowiadającym etapom planowania kopalni, tak by uwzględnić zakres dostępnych na każdym etapie danych. Zastosowano kodowanie alfanumeryczne dla wskazania metody urabiania w oparciu o dane o zwięzłości skały i ryzyko zagrożenia geotechnicznego. Kodowanie alfanumeryczne zostało następnie rozszerzone dla identyfikacji operacji górniczych w ramach kategorii „Poziom zagrożenia geotechnicznego”. Wskaźnik ten wykorzystywany jest jako wstępne narzędzie oceny ryzyka wystąpienia zagrożenia oraz klasyfikacji poziomu zagrożenia związanego z działalnością górniczą. Celem takiej klasyfikacji jest jej wykorzystanie jako wytycznych i uzasadnienia dla stosowania formalnych metod oceny ryzyka geotechnicznego.
    Źródło:
    Archives of Mining Sciences; 2015, 60, 1; 51-61
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cancer therapeutics strategy using nano-carrier mediated natural drugs
    Autorzy:
    Shaw, S.
    Singh, P.
    Mishra, R.
    Singh, R.
    Nayak, R.
    Bose, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2201053.pdf
    Data publikacji:
    2022
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    breast cancer
    porous silicon nanocarrier
    quercetin
    nucleolin
    targeted therapy
    rak piersi
    krzem porowaty
    nanonośniki
    kwercetyna
    terapia celowana
    Opis:
    Purpose Nucleolin is a multifactorial protein, having a significant role in chromatin remodelling, mRNA stability, ribosome biogenesis, stemness, angiogenesis, etc., thus, it is potential therapeutic target in cancer. The purpose of this paper is to study porous silicon (pSi) nanocarrier-based natural drug delivery system targeting dysregulated nucleolin expression for cancer therapeutics. Design/methodology/approach Quercetin was loaded in pre-synthesized and characterized pSi nanoparticles, and release kinetics was studied. The study compared the inhibitory concentration (IC50) of quercetin, synthetic drug doxorubicin, and quercetin-loaded pSi nanoparticles. Further, mRNA expression of a target gene, nucleolin, was tested with a quercetin treated breast cancer cell line (MCF-7). Findings Quercetin-loaded pSi nanoparticles followed first-order release kinetics. IC50 was determined at concentrations of 312 nM, 160 µM, and 50 µM against doxorubicin, quercetin, and quercetin-loaded pSi nanoparticles, respectively. The results further indicated 16-fold downregulation of nucleolin mRNA expression after 48h of quercetin treatment of exponentially growing MCF-7 cells. Research limitations/implications Whether pSi nanoparticle loaded quercetin can significantly downregulate nucleolin protein expression and its impact on apoptosis, cell proliferation, and angiogenic pathways need further investigation. Practical implications The practical application of the proposed nanocarrier-based drug delivery system potentially lays out a path for developing targeted therapy against nucleolin-dysregulated cancer using natural products to minimize the side effects of conventional chemotherapeutic drugs. Originality/value Inhibition of nucleolin and nucleolin regulated pathways using natural compounds and its targeted delivery with nanocarrier is not yet done.
    Źródło:
    Journal of Achievements in Materials and Manufacturing Engineering; 2022, 114, 1; 32--41
    1734-8412
    Pojawia się w:
    Journal of Achievements in Materials and Manufacturing Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new cyclotriveratrylene derivative as turn-off fluorescent probe with quinoline appended arm for the selective and sensitive determination of Cu2+ ions
    Autorzy:
    Fernandes, Patrick F.
    Mishra, Divya R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030477.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    8-quniolinesulfonyl chloride
    Fluorescence studies
    Sensors
    copper ions
    cyclotriveratrylene
    Opis:
    A novel supramolecular fluorescent molecular probe constructed on cyclotriveratrylene based derivative allied to 8-quinolinesulfonyl chloride (8QSC) was synthesized and used for the detection of copper ions among the various cations. Using 1H-NMR, 13C-NMR, and ESI-MS techniques the compound was successfully characterised. Furthermore the complexation behaviour of 8QSC-CTV with different cations were studied. A shift in the absorption spectra showed the detection of copper ion with the ligand 8QSC-CTV which concludes the strong binding interaction between the ligand and the cation. Furthermore the metal ion showed quenching in the emission spectra. The quantum yield of the metal complex was also studied. The stern volmer analysis concluded that the mechanism of fluorescence quenching is either purely dynamic or purely static.
    Źródło:
    World Scientific News; 2020, 144; 103-113
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanofluid motion past a shrinking sheet in porous media under the impact of radiation and heat source/sink
    Autorzy:
    Sharma, R. P.
    Jha, A. K.
    Gaur, P. K.
    Mishra, S. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/264665.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    magnetohydrodynamika
    promieniowanie cieplne
    wytwarzanie ciepła
    MHD
    nanofluid
    shrinking surface
    thermal radiation
    heat generation
    porous medium
    Opis:
    An investigation has been carried out for the MHD 3-dimensional flow of nanofluid over a shrinking sweet saturating a porous media in the presence of thermal radiation and heat generation. Convective boundary conditions for the flow phenomena are used in the present analysis. The governing equations are reduced to ODEs employing suitable similarity transformations. The solutions of formulated differential equations have been attained mathematically by fourth order R-K technique along with the shooting method. The impact of the governing constraints on momentum, heat, and local Nusselt number, are explored. It is noticed that the momentum and heat decrease with raise in the porosity variable, temperature reduces with an enhance in the thermal radiation variable, and temperature enhances with an enhance in the heat source/sink parameter.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 183-199
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Two-Parameter Lindley Distribution
    Autorzy:
    Shanker, R.
    Mishra, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/465861.pdf
    Data publikacji:
    2013
    Wydawca:
    Główny Urząd Statystyczny
    Tematy:
    Lindley distribution
    moments
    failure rate function
    mean residual life function
    stochastic ordering
    estimation of parameters
    goodness of fit
    Opis:
    A two-parameter Lindley distribution, of which the Lindley distribution (LD) is a particular case, has been introduced. Its moments, failure rate function, mean residual life function and stochastic orderings have been discussed. The maximum likelihood method and the method of moments have been discussed for estimating its parameters. The distribution has been fitted to some data-sets to test its goodness of fit.
    Źródło:
    Statistics in Transition new series; 2013, 14, 1; 45-56
    1234-7655
    Pojawia się w:
    Statistics in Transition new series
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Drag on a permeable sphere placed in a micropolar fluid with non-zero boundary condition for microrotations
    Autorzy:
    Mishra, V.
    Gupta, B. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/122361.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    drag force
    modified Bessel’s function
    micropolar fluid
    permeable sphere
    stream function
    siła tarcia
    funkcja Bessela
    Opis:
    This paper concerns an analytical study of an infinite expanse of uniform flow of steady axisymmetric creeping flow of an incompressible micropolar fluid around the permeable sphere assuming a nonhomogeneous boundary condition for microrotation vector. It is assumed that microrotation vector is proportional to the rotation rate of velocity vector. The stream function solutions for the flow fields are obtained in the terms of modified Bessel’s functions and Gegenbauer functions. Continuity of normal velocity, no-slip condition, non-zero microrotation vector on the sphere, uniform velocity at infinity are the different boundary conditions used to determine the flow fields explicitly. The microrotation component, pressure field, bounds of permeability parameter and drag force experienced by the permeable sphere are calculated. Dependence of the drag force on different fluid parameters is presented graphically and discussed. It is found that drag force decreases with increasing spin parameter. Several cases of interest are deduced from the present analysis.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2016, 15, 3; 97-109
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Agricultural commodities: An integrated approach to assess the volatility spillover and dynamic connectedness
    Autorzy:
    Mishra, Arunendra
    Kumar, R Prasanth
    Powiązania:
    https://bibliotekanauki.pl/articles/1891375.pdf
    Data publikacji:
    2021-12-17
    Wydawca:
    Uniwersytet Ekonomiczny w Poznaniu
    Tematy:
    dynamic connectedness
    TVPVAR
    price volatility
    volatility spillover
    ag ricultural commodities
    network diagrams
    Opis:
    In this article the dynamic connectedness between the five agricultural commodities is examined by implementing the Diebold and Yılmaz (VAR based) and Time Varying Parameter Vector Autoregressions (TVP-VAR) measures for understanding the time-varying variance-covariance mechanism using daily data for the period of 2005 to 2019. The findings reveal that at an overall level all the commodity prices are less susceptible to significant volatility shocks from other commodities specifically before the introduction of the pan-India electronic trading portal (eNAM). Cotton prices do not show any variation due to spillover from others for the entire study period. The volatility spillover is visible post eNAM period particularly for the commodity stock prices. Whereas at an overall level the total directional connectedness has gone down in the post eNAM era. The network analysis suggests that the commodity stock prices show a stronger association as compared to market prices. Generally commodity prices show volatility connectedness but with respect to their own market which means strong spillover is missing among both the markets.
    Źródło:
    Economics and Business Review; 2021, 7, 4; 28-53
    2392-1641
    Pojawia się w:
    Economics and Business Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Rising Demand for Rain Water Harvesting System in the World: A Case Study of Joda Town, India
    Autorzy:
    Krishna, R. S.
    Mishra, Jyotirmoy
    Ighalo, Joshua O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1031604.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Groundwater
    Harvesting
    Joda
    Rainwater
    Water Resources Management
    Opis:
    Worldwide, annual water demand has been increased for different uses. This can be attributed to population expansion and the accompanying need to satisfy their water needs for domestic, agricultural, and industrial purposes. The situation has been becoming worst due to vulnerable and inefficient water supply systems. Rainwater harvesting (RWH) has been proved to be a sustainable option in solving the on-ground water shortage to a great extent. India has been facing the wrath of a water crisis for about a decade or two. The potential of RWH in India is more due to its geographical location and landscape. This paper aims at studying the impact of adopting RWH techniques as an artificial recharge option to evaluate groundwater table in the Joda town of India by analyzing the difference in water levels of the township throughout the past decade (2009-19). The study revealed the increase in the underground water level of the study area and established that RWH systems are crucial in arid regions to a large extent.
    Źródło:
    World Scientific News; 2020, 146; 47-59
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mathematical modeling of magneto pulsatile blood flow through a porous medium with a heat source
    Autorzy:
    Sharma, B. K.
    Sharma, M.
    Gaur, R. K.
    Mishra, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/266184.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    heat source
    blood flow
    porous medium
    MHD
    źródło ciepła
    przepływ krwi
    materiały porowate
    magnetohydrodynamika
    Opis:
    In the present study a mathematical model for the hydro-magnetic non-Newtonian blood flow in the non-Darcy porous medium with a heat source and Joule effect is proposed. A uniform magnetic field acta perpendicular to the porous surface. The governing non-linear partial differential equations have been solved numerically by applying the explicit finite difference Method (FDM). The effects of various parameters such as the Reynolds number, hydro-magnetic parameter, Forchheimer parameter, Darcian parameter, Prandtl number, Eckert number, heat source parameter, Schmidt number on the velocity, temperature and concentration have been examined with the help of graphs. The present study finds its applications in surgical operations, industrial material processing and various heat transfer operations.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2015, 20, 2; 385-396
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An overview of current research trends on graphene and it’s applications
    Autorzy:
    Krishna, R. S.
    Mishra, Jyotirmoy
    Das, Shaswat Kumar
    Mustakim, Syed Mohammed
    Powiązania:
    https://bibliotekanauki.pl/articles/1068613.pdf
    Data publikacji:
    2019
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Concrete
    Doping
    Electrical
    Graphene
    Material
    Mechanical
    Properties
    Sustainability
    Opis:
    Graphene is no doubt called a wonder-material due to its outstanding superlative traits. It has its application near about in every field. Its properties are extraordinary and different from any day-to-day material. Albeit bearing such qualities, its structure is rather simple than most individuals cerebrate of. It has a thickness of an atom. It is a two-dimensional carbon arranged in a honeycomb crystal structure. It could transmute the way we view, in numerous fields of science. Its applications can be an asset to a greener environment for which Graphene engineered cement/concrete composites have an immense potential in the present times when sustainable construction materials are the need of the hour. Graphene can act as a good adsorbent for pollutant abstraction due to its high surface area. Either alone or in coalescence with different materials, it very well may be used for the debasement or deliberation of a sizably voluminous assortment of contaminants through a few strategies. Incipient heights can be achieved as the list of operations for graphene is virtually illimitable. Utilization of graphene in the coming years will give inundating difference to current technologies. This paper fixates on the applications and developments of Graphene in fields like Electronics, Batteries, Filtration, Medicine, Construction, and Composites.
    Źródło:
    World Scientific News; 2019, 132; 206-219
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Antidiabetic and antiplatelet aggregation study of various methanol fractions of Nymphaea stellata Willd. leaves
    Studium działania przeciwcukrzycowego i antyagregacyjnego różnych frakcji wyciągu metanolowego z liści Nymphaea stellata Willd
    Autorzy:
    Raja, M.M.
    Mishra, S.H.
    Tamboli, R.S.
    Agilandeswari, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/950585.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Włókien Naturalnych i Roślin Zielarskich
    Tematy:
    stz-nad
    ptp1b inhibition
    adp induced
    co-tlc
    histopathology
    Opis:
    Introduction: Nymphaea stellata Willd. (Nymphaeaceae) is traditionally used for the treatment of diabetes. Alcohol extract of N. stellata leaves has been reported for hypoglycaemic activity. Objective: The aim of this study was to further investigate the different methanol fractions of N. stellata leaves for anti-diabetic activity and anti-platelet aggregation activity. Methods: Methanol extract was fractioned in to unsaponified petroleum ether fraction of methanol extract (UPFME), chloroform fraction of methanol extract (CFME) and residual fraction of methanol extract (RFME). All fractions were evaluated for in vivo anti-diabetic activity (STZ-NAD-induced rat model), in vitro anti-diabetic activity (PTP1B inhibition study) and anti-platelet aggregation activity. Results: UPFME showed significant changes in all studied parameters, compared to the diabetic control. UPFME also showed an IC50 value of 19.30±1.1 mg/ml and 13.11±0.7 μg/ml in PTP1B inhibition study and anti-platelet aggregation study, respectively. Conclusion: The study indicates that UPFME of N. stellata leaves exhibit anti-diabetic and anti-platelet aggregation activity.
    Wstęp: Nymphaea stellata Willd. (Nymphaceae) jest tradycyjnie stosowana w leczeniu cukrzycy. Istnieją doniesienia o działaniu hipoglikemicznym wyciągu alkoholowego z liści tej rośliny. Cel: Celem pracy były dalsze badania właściwości przeciwcukrzycowych i antyagregacyjnych różnych frakcji metanolowego wyciągu z liści N. stellata. Metodyka: Ekstrakt metanolowy frakcjonowano na niezmydloną frakcję otrzymaną za pomocą eteru naftowego (UMFME), frakcję otrzymaną za pomocą chloroformu (CFME) oraz pozostałość ekstraktu metanolowego (RFME). Wszystkie frakcję były badane w kierunku działania przeciwcukrzycowego in vivo (w modelu szczurzym cukrzycy wywołanej przy pomocy STZ-NAD), w kierunku aktywności przeciwcukrzycowej w badaniach in vitro (badania hamowania PTP1B) oraz w celu określenia aktywności antyagregacyjnej. Wyniki: Stosowanie frakcji UMFME powodowało znaczące zmiany we wszystkich badanych parametrach zwierząt doświadczalnych (w porównaniu do grupy kontrolnej z wywołaną cukrzycą). Wartość IC50 dla frakcji UMFME wynosiła 19,30±1,1 μg/ml w badaniu hamowania PTP1B oraz 13,11±0,7 μg/ml w badaniu działania antyagregacyjnego. Wnioski: Otrzymane wyniki badań wskazują, że frakcja UMFME z liści N. stellata wykazuje aktywność przeciwcukrzycową i antyagregacyjną.
    Źródło:
    Herba Polonica; 2017, 63, 3
    0018-0599
    Pojawia się w:
    Herba Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies on FOX-7 Based Melt Cast High Explosive Formulations
    Autorzy:
    Mishra, V. S.
    Vadali, S. R.
    Garg, R. K.
    Joshi, V. S.
    Wasnik, R. D.
    Asthana, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/358915.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    melt cast
    FOX-7
    LOVEX
    shock sensitivity
    VOD
    impulse
    IMs
    Opis:
    The key driving force in modern explosive research is the development of low vulnerable high explosive (LOVEX) compositions for future applications in insensitive munitions (IMs). The increasing demand for LOVEX has led to exhaustive studies on low vulnerable explosives as a replacement for conventional cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) in 2,4,6-trinitrotoluene (TNT) melt cast high explosive formulations. In the present study, 1,1-diamino-2,2dinitroethene (FOX-7) has been evaluated as a possible RDX replacement in TNT based, non-aluminized as well as aluminized, melt cast formulation. FOX-7 based melt cast formulations were characterized for their sensitivity to mechanical/shock stimuli, velocity of detonation (VOD), blast parameters and thermal decomposition behavior. These characteristics are compared with the corresponding RDX based compositions as reference standard. The studies show that with little sacrifice on performance parameters, FOX-7 based, non-aluminized and aluminized, melt cast formulations are found to be less vulnerable, compared with the corresponding RDX based formulations.
    Źródło:
    Central European Journal of Energetic Materials; 2013, 10, 4; 569-580
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fabrication and Characterization of Al6061-Nano Al2O3 Composites by Ultrasonic Assisted Stir Casting followed by Heat Treatment and Hot Forging
    Autorzy:
    Purohit, Rajesh
    Qureshi, M.M.U.
    Kumar, Ashish
    Mishra, Abhishek
    Rana, R.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/28099519.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    Al6061 alloy
    Al6061-Al2O3 nanocomposites
    XRD analysis
    FESEM
    mechanical properties
    automotive gears
    Opis:
    The present work comprises the development of Al6061/nano Al2O3 composites with 0 to 4 weight percent in steps of 0.5 wt. % of nano alumina particles by using ultrasonic assisted stir casting. Casted samples were subjected to heat treatment and hot forging. Further forged and heat-treated gear blanks of nano Al2O3 (0 to 3.0 weight %) reinforced nanocomposites were machined to make spur gears for the wear test. The results have shown that nano Al2O3 reinforcement in the Al6061 matrix with heat treatment and forging improves the hardness and compressive strength up to 3.5 wt. %, after that, it starts decreasing because of the agglomeration of nano alumina particles. SEM results reveal grain refinement of the pure alloy after reinforcement. Removal of porosity and voids observed after forging operation. Wear resistance increasing with incorporation of Al2O3 nanoparticles in base alloy, reinforcement wt. %, precipitation hardening and hot forging also improves wear resistance and mechanical properties. These composites have widespread applications in gear, brake discs, crankshaft, clutch plates, pistons, and other components of automobiles and aircraft structures.
    Źródło:
    Archives of Metallurgy and Materials; 2023, 68, 2; 791--798
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Tungsten on Aluminized Melt Cast High Explosive Formulations
    Autorzy:
    Mishra, V. S.
    Bhagat. A., L.
    Vadali, S. R.
    Singh, V. K.
    Wasnik, R. D.
    Asthana, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/358355.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    tungsten
    MOUT
    low intensity conflict
    peak over pressure
    impulse
    Opis:
    Aluminized 2,4,6-trinitrotoluene (TNT) based, melt-cast, high explosive compositions are widely used in warheads. These compositions offer a blast effect over a larger period due to the secondary combustion of aluminum. During recent times tungsten based explosives have been reported for lethality at close range to avoid collateral damage in low intensity conflicts (LIC) and find application in shaped charges to enhance their penetration capability. This paper reports findings on tungsten-based, melt-cast, explosive formulations. The compositions were prepared by substituting aluminum with tungsten in the reference aluminized, high explosive formulation. The compositions were characterized for their sensitivity to mechanical/shock stimuli, velocity of detonation (VOD) and blast performance. The study reveals that the impact sensitivity remains comparable on incorporating 10% tungsten at the cost of aluminum whereas an increase in tungsten content to 20% leads to an increase in impact sensitivity. However friction sensitivity and shock sensitivity remained more or less unchanged. The velocity of detonation (VOD) of tungsten-loaded, aluminized formulations is found to be comparable to the standard aluminized formulation. The peak over pressure of tungsten-based formulations is lower than the reference, aluminized composition at close range but is almost unchanged at long range. The impulse of tungsten-based formulations is also lower than the reference, aluminized composition. The reduction in impulse at close range is substantial on replacing 10% aluminum with inert tungsten.
    Źródło:
    Central European Journal of Energetic Materials; 2012, 9, 2; 147-154
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies on NTO-, FOX-7- and DNAN-based Melt Cast Formulations
    Autorzy:
    Mishra, V. S.
    Vadali, S. R.
    Bhagat, A. L.
    Garg, R. K.
    Kugaonkar, V. M.
    Raman, S.
    Sinha, R. K.
    Asthana, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/358500.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    melt cast
    DNAN
    TNT
    FOX-7
    NTO
    RDX/TNT
    VOD
    sensitivity
    Opis:
    In the present paper, 2,4-dinitroanisole (DNAN) has been evaluated as a melt cast explosive in comparison to the widely used 2,4,6-trinitrotoluene (TNT). The detonation failure diameter of a bare DNAN charge is greater than 100 mm and about 44 mm with 1.5 mm steel confinement. Comparative studies of two sets of formulations were carried out. The first set comprised formulations containing 60% of NTO, FOX-7, HMX or RDX and 40% of DNAN or TNT. The second set comprised formulations containing 30% of NTO, FOX-7, TATB or RDX and 70% of DNAN or TNT. The studies were mainly concentrated on characterization of the formulations, which included determination of the sensitivity parameters and the velocity of detonation (VOD). The study confirmed that DNAN and DNAN-based formulations are relatively insensitive compared to TNT and the analogous TNT-based formulations respectively. The rate of the detonation reaction of DNAN is enhanced in the presence of the high energy ingredients RDX, HMX, FOX-7 and NTO to varying degrees. The VODs of the FOX-7/TNT and RDX/TNT formulations match closely with the proportions of FOX-7 and RDX under study. The VOD and shock sensitivity of the FOX-7/DNAN formulations decrease rapidly compared to the RDX/DNAN formulations, with increases in the proportion of FOX-7 or RDX. The combinations of NTO with TNT, and NTO with DNAN, are more shock insensitive than TNT or DNAN alone. NTO-based compositions are more insensitive than FOX-7-based compositions.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 2; 403-417
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Leaching of Al-Based Polygrain Quasicrystalline and Related Crystalline Surfaces
    Autorzy:
    Yadav, T.
    Mishra, S.
    Pandey, S.
    Singh, D.
    Lowe, M.
    Tamura, R.
    Mukhopadhyay, N.
    Srivastava, O.
    McGrath, R.
    Sharma, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1373698.pdf
    Data publikacji:
    2014-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.44.Br
    81.16.Hc
    61.66.Dk
    68.37.Hk
    Opis:
    In the present investigation, we have studied leaching on polygrain Al-based quasicrystalline $(i-Al_{63}Cu_{25}Fe_{12})$ as well as crystalline (B2 phase; $Al_{55}Cu_{30}Fe_{15})$ alloy surfaces using a 10 mole NaOH solution. The surface was leached at varying times from 30 min to 8 h and subsequently characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. Leaching of the samples for 30 min generated a homogeneous layer. However further leaching for 1-8 h yielded nano-size particles on the surface. Spherical microstructure has been observed on the Al-Cu-Fe crystalline surface whereas on the quasicrystalline surface a petal-like microstructure appeared. The implications of the evolution of different microstructures in the context of structure, stability and activity are discussed. The results are compared with the microstructure of leached polygrained samples containing a mixture of different surface orientations.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 2; 629-632
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An extension of line spring model for vibration analysis of thin isotropic plate containing multiple part-through cracks: an analytical approach
    Autorzy:
    Jain, N. K.
    Gupta, A.
    Salhotra, R.
    Rawani, A. M.
    Soni, S.
    Mishra, A.
    Joshi, P. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/128046.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    multiple cracks
    Line Spring Model
    vibration
    partial crack
    pęknięcie wielokrotne
    sprężyna liniowa
    drgania
    pęknięcie częściowe
    Opis:
    In the present study, the effect of multiple part-through cracks on the vibration characteristics of thin isotropic rectangular plate is presented. The proposed analytical model is developed using Kirchhoff’s classical plate theory and the crack terms are formulated using the simplified Line Spring Model (LSM). The application of Berger's formulation helps to transform the derived governing equation in the form of well known Duffing equation with cubic nonlinearities and then the solution for final governing equation is obtained using Galerkin's method for two different boundary conditions. The fundamental frequency of the plate as affected by the number of cracks, cracks length, cracks orientation, and plate aspect ratio for different boundary condition is presented. It is found that the results obtained for natural frequencies are maximally affected by number of cracks, crack length and orientations.
    Źródło:
    Vibrations in Physical Systems; 2018, 29; 1-25
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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