5,008 research outputs found

    La política nacional pakistaní para los refugiados

    Get PDF
    Como preparación de cara a 2014 y al impacto de la “transición” en Afganistán, la nueva Política Nacional para los Refugiados pakistaní trata de abordar las incertidumbres y las realidades a las que se enfrentan los refugiados afganos en Pakistán

    Higher Dimensional Inhomogeneous Perfect Fluid Collapse in \emph{f(R)} Gravity

    Full text link
    This paper is about the n+2n+2-dimensional gravitational contraction of inhomogeneous fluid without heat flux in the framework of f(R)f(R) metric theory of gravity. Matching conditions for two regions of a star has been derived by using the Darmois junction conditions. For the analytic solution of equations of motion in modified f(R)f(R) theory of gravity, we have taken scalar curvature as constant. Hence final result of gravitational collapse in this frame work is the existence of black hole and cosmological horizons, both of these form earlier than singularity. It has been shown that constant curvature term f(R0)f(R_{0}) (R0R_0 is constant scalar curvature) slows down the collapsing process.Comment: 17 Pages, to appear in European Physical Journal

    Effect of Foliar and Soil Application of Plant Nutrients from Different Fertilizer Sources on Growth of Peach [Prunus persica (L.) Batsch] Saplings

    Get PDF
    A field experiment on growth of peach saplings as influenced by plant nutrients from different fertilizer sources and application methods, was conducted at Agriculture Research Institute, Mingora, Pakistan during 2014-15. The field was prepared before November and local peach seeds were sown with 2 ft row to row distance in 5 ft long rows. T-budding with “Springcrest” scion was done in June 2015. The experiment was laid out in RCBD split-plot arrangement with three replications. The main-plot treatments consisted of 1) control, 2) soil application of N-P (100 : 80 kg P2O5 : K2O ha-1), 3) foliar application of N-P-K (17-17-17 N-P2O5-K2O @ 20 g L-1), 4) foliar application of N-P-K-S (20-8-14-10 N-P2O5-K2O-S @ 20 g L-1), and 5) foliar application of urea (20 g urea L-1), and sub-plot treatments were, 1) control,  2) soil application of urea fertilizer (120 kg N ha-1), and 3) soil application of Ammonium Sulphate fertilizer (120 kg N ha-1). Soil fertilizers were broadcasted on 3rd August 2015 and foliar were applied with small hand pump. The data were recorded from 4th August to 2nd December, 2015 at 15 days interval. Analysis of data revealed that the effect of fertilizer treatments on plant height and stem diameter of peach saplings was significant. Maximum plant height (151.67 cm) and stem diameter (15.98 mm) were gained by plants receiving fertilizer treatment of urea foliar (2%) and ammonium sulphate as a soil application. It was concluded from this study that fertilizer treatments of urea foliar (2%) and ammonium sulphate as a soil application increased plant height and stem diameter of peach saplings and hence are recommended for peach saplings of first year growth. Keywords: foliar fertilizer, peach growth, peach nutrition, peach saplings, Prunus persica, foliar applicatio

    Topological Sensitivity Based Far-Field Detection of Elastic Inclusions

    Full text link
    The aim of this article is to present and rigorously analyze topological sensitivity based algorithms for detection of diametrically small inclusions in an isotropic homogeneous elastic formation using single and multiple measurements of the far-field scattering amplitudes. A L2L^2-cost functional is considered and a location indicator is constructed from its topological derivative. The performance of the indicator is analyzed in terms of the topological sensitivity for location detection and stability with respect to measurement and medium noises. It is established that the location indicator does not guarantee inclusion detection and achieves only a low resolution when there is mode-conversion in an elastic formation. Accordingly, a weighted location indicator is designed to tackle the mode-conversion phenomenon. It is substantiated that the weighted function renders the location of an inclusion stably with resolution as per Rayleigh criterion.Comment: 31 pages, 1 figur

    Production, functionalization and application of carbon materials.

    Get PDF
    The work of this thesis was structured into 2 main activities: (1) to devise a surface functionalization technique for commercial carbon fibres (CFs) based on lignin precursor developed under the European Union FP7 Project “Functionalized Innovative Carbon Fibres Developed from Novel Precursors with Cost Efficiency and Tailored Properties” (FIBRALSPEC), grant agreement No. 604248. (2) To perform the exploration of low cost carbon fillers for application to polymer composites. 1st chapter presents a general introduction of the different carbon materials and their applications. 2nd chapter is concerned with the existing commercial carbon fibre manufacturing techniques and precursors. A small portion on the surface modification techniques is also added in this chapter. The 3rd chapter deals with the production techniques and limitations of Carbon nano tubes as a filler for the application to composites. A brief introduction on biochar materials has been added as well. The 4th chapter deals with functionalization study of commercial carbon fibres and lignin based carbon fibres. Commercial carbon fibres T700 were purchased from Toray, Japan to study the surface modification through low pressure oxygen plasma at Polito. Treatment parameters in an oxygen environment such as holding time (1~10 minutes), plasma power (100~200 W), flow rate (250 Standard Cubic Centimeters) and plasma chamber pressure (53 Pa) were set. Morphology of the carbon fibres before and after plasma treatment was studied through Field Emission Scanning Electron Microscopy (FESEM). Chemical nature of the functional groups formed on the carbon fibres surface after the treatment was studied through Fourier Transform Infrared (FTIR) spectroscopy and atomic percent was quantified through X-Ray Photoelectron Spectroscopy (XPS). Raman spectroscopy was carried out to study the structural changes in the carbon fibres. Wettability test was carried out to study the interaction of the surface functional groups with epoxy matrix. Tensile strength of the CFs was determined after the plasma treatment to ensure optimum mechanical performances of the treated fibres in the subsequent composites. In order to ensure the effectiveness of the plasma treatment the same samples were studied after six months of storage in ambient conditions. On the basis of the obtained results from the activities above, optimum plasma treatment parameters such as treatment time, plasma power, oxygen flow rate, plasma chamber pressure were singled out and applied on the lignin based carbon fibres. The lignin based CFs were plasma treated for 5 minutes at 100 W and 200W at a flow rate of 250 SCCM and 53 Pa plasma chamber pressure. Surface morphology was studied through FESEM. Plasma treated fibres showed canals and pits on the surface. The fibre started to damage at a plasma power of 200W. Also the oxygen pickup reduced at this treatment power as depicted by the XPS analysis. The 200 W, 5 minutes treatment was identified as an upper limit for the treatment parameter. The treated fibres were shredded finely and dispersed in epoxy resin using an overhead mixer to produce composites. Mechanical and tribological analysis was carried out and compared with the neat epoxy and untreated CFs composites. The plasma treated carbon fibre composites outperformed their counterparts. Based on the observations we recommended low pressure oxygen plasma treatment for the surface modification of the lignin based carbon fibres intended for commercial use. To further support our recommendations we produced carbon fibers from waste cotton clothes in Polito and applied the same treatment to them. The temperature profile for the thermal treatment was deduced from thermogravimetric analysis of cotton fibres in argon environment. XPS and FTIR analysis was carried out to ensure the absence of any impurity in the cotton fabrics. Carbonization process was carried out in a Carbolite furnace (TZF12/65/550) at the temperatures of 400o C, 600o C and 800o C for one hour in nitrogen environment at a ramp rate of 15o C/minute. The sample prepared at 800o C was selected to study the plasma treatment due to its more ordered structure and high carbon content as depicted by the Raman and XPS analysis respectively. The carbon fibres were treated with oxygen plasma at 100 W and 200 W for 5 minutes. Surface morphology and structure of the treated CFs were studied via FESEM and Raman spectroscopy. Surface of the treated fibres showed pits and canals confirming the action of the plasma elements while a degradation of the ID/IG ratio in the Raman spectra evidenced the effects of the plasma elements on the structure of the CFs. The functional groups on the surface of the plasma treated CFs were studied through X-Ray Photoelectron Spectroscopy and Fourier Transform Infrared spectroscopy. Chemical groups like alcohols, carboxyl and carbonyl were found on the surface of the treated CFs. BET analysis showed that surface area of the fibers increased after treatment. The plasma treated CFs retained higher amount of the epoxy resin in the wettability test. The plasma treated fibres were applied in composites. Epoxy based composites were fabricated with the pristine and treated CFs in 1% and 3% by weight. Mechanical and tribological analysis was carried out on all composites. The composites of the plasma treated fibres showed superior mechanical and tribological properties when compared to their untreated CFs counterparts. Morphology of the mechanical and tribological specimen were studied with FESEM to investigate the interaction of the filler with the matrix. Above results supported our earlier argument and low pressure oxygen plasma was recommended as a suitable treatment for the modification of the carbon fibres. The 2nd part of the thesis emphasizes the application of cheap precursor based carbon materials for the tailoring of composites properties. In recent years, low-cost carbons derived from recycled materials have gained a lot of attention for their potentials as filler in composites and in other applications. The electrical, frictional and mechanical properties of polymer composites can be tailored using different percentages of these fillers. In the Carbon lab at Polito we synthesized carbon nano materials (CNMs) from waste polyethylene bags in two different morphologies namely carbon nano beads (CNBs) (P1) and a mix of carbon nano tubes (CNTs) and carbon nano beads (P2) using chemical vapour deposition (CVD) technique by varying the carrier gas pressure. Morphology of the CNMs were studied through FESEM and their purity through Thermogravimetric Analysis (TGA) and Raman spectroscopy. Epoxy based composites were fabricated using these CNMs as filler in 1% and 3 % by weight. Mechanical properties and tribological properties were compared with the epoxy composites of commercial Multi Walled Carbon Nano Tubes (MWCNT). It is observed that the in house generated CNMs composites show overall better mechanical and tribology properties compared to the neat epoxy and the commercial MWCNTs based composites. Morphology of the composites was analysed through FESEM to study the interaction of the filler with the matrix that lead to improved performances. A model on the fracture behaviour was proposed on basis of FESEM analysis. Chapter 6 is concerned with this activity. In chapter 7, the maple based biochar has been explored as a cheap alternative filler to enhance the polymer properties. In this regard, the mechanical, tribological and electrical behavior of composites with two types of biochar based on maple wood namely biochar and biochar HT were investigated and compared with those of a composite containing multiwall carbon nanotubes. HT is heat treated at 900o C in nitrogen at 1 hour. Superior mechanical properties (ultimate tensile strength, Young modulus and tensile toughness) were noticed at low biochar concentrations 2~4 wt. %). Biochar based composites showed equivalent tribology properties to the composites fabricated with MWCNTs. Furthermore, dielectric properties in the microwave range comparable to low carbon nanotubes loadings can be achieved by employing larger but manageable amounts of biochar (20 wt. %) rending the production of composites for structural and functional application cost-effective. Conclusive remarks and future plans are compiled in chapter 8

    In-vitro anticoccidial potential of Saccharum officinarum extract against Eimeria oocysts

    Get PDF
    Present study was conducted to evaluate the effect of aqueous methanolic extract from Saccharum officinarum on the sporulation and morphology of oocysts of four Eimeria species (Eimeria tenella, E. necatrix, E. mitis, E. brunetti) of poultry. Sporulation inhibition bioassay was used to evaluate the activity of Saccharum officinarum extract (SOE) on the sporulation of coccidian oocysts. In this assay, unsporulated oocysts were exposed to six concentrations of S. officinarum in 10% dimethyl sulfoxide solution (w/v; 10, 5, 2.5, 1.25, 0.625 and 0.31%) while DMSO and potassium dichromate solution (K2Cr2O7) served as control groups. The Petri dishes were partially covered to allow the passage of oxygen and incubated at 25-29° C for 48 h, providing 60-80% humidity. The sporulation of the oocyst was confirmed by examining sporocysts under inverted microscope at 40x. Results showed anticoccidial activity of SOE against all Eimeria species as proved by its ability to inhibit the sporulation of the oocysts under laboratory conditions. Inhibition of sporulation was observed in dose dependent manner. S. officinarum extract at higher dose also damaged the normal morphology and shape of oocysts of Eimeria species

    M-ATTEMPT: A New Energy-Efficient Routing Protocol for Wireless Body Area Sensor Networks

    Get PDF
    In this paper, we propose a new routing protocol for heterogeneous Wireless Body Area Sensor Networks (WBASNs); Mobility-supporting Adaptive Threshold-based Thermal-aware Energy-efficientMulti-hop ProTocol (M-ATTEMPT). A prototype is defined for employing heterogeneous sensors on human body. Direct communication is used for real-time traffic (critical data) or on-demand data while Multi-hop communication is used for normal data delivery. One of the prime challenges in WBASNs is sensing of the heat generated by the implanted sensor nodes. The proposed routing algorithm is thermal-aware which senses the link Hot-spot and routes the data away from these links. Continuous mobility of human body causes disconnection between previous established links. So, mobility support and energy-management is introduced to overcome the problem. Linear Programming (LP) model for maximum information extraction and minimum energy consumption is presented in this study. MATLAB simulations of proposed routing algorithm are performed for lifetime and successful packet delivery in comparison with Multi-hop communication. The results show that the proposed routing algorithm has less energy consumption and more reliable as compared to Multi-hop communication.Comment: arXiv admin note: substantial text overlap with arXiv:1208.609

    Intelligent Transportation System for Smart-Cities using Fuzzy Logic

    Get PDF
    According to United Nations population statistics 2017, the world population is 7.6 billion and is growing rapidily alomost 11 billion by end of 21 century with a 70% chance of continued growth, this rapid increasing population have created low standards of living in cities. Smart Cities are facing pressures associated with due innovations and globalization to improve their citizens life. Computational intelligence is the study of adaptive mechanism to facilitate intelligent behavior in changing and complex environments. Traffic congestion and monitoring has become one of the critical issues in big cities. The adaptive mechanism of computational intelligence in changing the behavior of complex environments of smart city is very effective. The developing framework and services for smart-city requires sound infrastructure, latest current technology adoption. A framework model with the integration of cloud-data, social network (SN) services that is collecting stream data with smart sensors in the context of smart cities is proposed. The adaptive mechanism of computational intelligence in changing thebehavior of complex environments of smart city is very effective. A radical framework that enables the analysis of big-data sets stemming from Social Networking (SN) sites. Smart cities understanding is a broad concept only city transportation sector is focused in this article. Fuzzy logic modeling techniques are used in many fields i.e. medical, engineering. business and computing related problems. To solve various traffic management issues in cities a detailed analysis of fuzzy logic system is proposed. This paper presents an analysis of the results achieved using Fuzzy Logic System (FLS) for smart cities. The results are verified using MATLAB Simulation
    corecore