3,880 research outputs found
Chiral Magnetic Effect in the Anisotropic Quark-Gluon Plasma
An anisotropic thermal plasma phase of a strongly coupled gauge theory can be
holographically modelled by an anisotropic AdS black hole. The temperature and
anisotropy parameter of the AdS black hole background of interest [1] is
specified by the location of the horizon and the value of the Dilaton field at
the horizon. Interestingly, for the first time, we obtain two functions for the
values of the horizon and Dilaton field in terms of the temperature and
anisotropy parameter. Then by introducing a number of spinning probe D7-branes
in the anisotropic background, we compute the value of the chiral magnetic
effect (CME). We observe that in the isotropic and anisotropic plasma the value
of the CME is equal for the massless quarks. However, at fixed temperature,
raising the anisotropy in the system will increase the value of the CME for the
massive quarks.Comment: 22 pages, 8 figure
Phosphate removal from aqueous solutions using polyaniline/ Ni0.5Zn0.5Fe2O4 magnetic nanocomposite
Background: Phosphorus is an indispensable element for the growth of animals and plants. There are
several environmental problems related to phosphate; therefore, the technical and economic methods
of removing phosphate are of great importance. This study evaluated the efficiency of polyaniline/
Ni0.5Zn0.5Fe2O4 magnetic nanocomposite in removing phosphate from aqueous environments.
Methods: The adsorbent was characterized by several methods, including X-ray diffraction (XRD),
scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Fourier transform
infrared (FT-IR) spectroscopy. Then, the potential of the adsorbentto adsorb phosphate was investigated.
The effects of the parameters of contact time (5-60 minutes), pH (3-9), adsorbent dosage (0.05-0.6 g),
and initial phosphate concentration (2-100 mg/L) on the phosphate removal yield were studied. All
phosphate ion concentrations were measured using the ammonium molybdate spectrophotometric
method.
Results: The results showed that a time of 30 minutes, pH of 5, and adsorbent dose of 0.4 g were the
optimum conditions for phosphate removal through adsorption. Increasing the initial concentration of
phosphate from 2 to 100 mg/L decreased the removal efficiency from 90.3% to 32%. The experimental
data was fitted well with the Freundlich isotherm model (R2 = 0.997).
Conclusion: Polyaniline/Ni0.5Zn0.5Fe2O4 magnetic nanocomposite removes phosphate from aqueous
solutions with a simple and environmentally benign procedure. The maximum adsorption capacity
based on Langmuir isotherm (R2 = 0.931) is 85.4 mg/g. This magnetic nanocomposite is applicable in
managing water resource pollution caused by phosphate ions
Pengaruh Panjang Serat terhadap Nilai Koefisien Absorpsi Suara dan Sifat Mekanik Komposit Serat Ampas Tebu dengan Matriks Gipsum
Penelitian ini dilakukan untuk membuat material komposit gipsum berpenguat serat alam untuk bahan penyerap suara. Permasalahan yang dikaji adalah untuk mengetahui hubungan panjang serat pada komposit ampas tebu bermatrik gipsum terhadap nilai koefisien absorpsi suara (α), kekuatan tekan, dan kekuatan lenturnya. Panjang serat yang digunakan adalah 10mm, 30mm, dan 50mm dengan fraksi volum 30% serat : 70% gipsum. Tujuannya untuk mendapatkan hubungan nilai koefisien absorpsi suara, kuat lentur, dan kuat tekan dengan panjang serat yang diberikan serta aplikasinya dalam material bahan penyerap suara yang memenuhi standar ISO 11654. Metode pembuatan spesimen komposit yang digunakan adalah hand lay up. Metode pengujian berdasarkan standart ASTM E1050 untuk pengujian koefisien absorpsi suara, ASTM D790 untuk pengujian kuat lentur, dan ASTM D695 untuk pengujian kuat tekan. Dari hasil pengujian didapatkan nilai koefisien absorpsi suara memenuhi standar ISO 11654 dengan nilai koefisien α lebih besar dari 0,15. Nilai kuat lentur terbaik ialah pada panjang serat 30mm sebesar 1,952 MPa. Nilai kuat tekan terbaik ialah pada panjang serat 50mm sebesar 2,005 MP
Quadrotor UAV indoor localization using embedded stereo camera
Localization of Small-Size Unmanned Air Vehicles (UAVs) such as the Quadrotors in Global Positioning System (GPS)-denied environment such as indoors has been done using various techniques. Most of the experiment indoors that requires localization of UAVs, used cameras or ultrasonic sensors installed indoor or applied indoor environment modification such as patching (Infra Red) IR and visual markers. While these systems have high accuracy for the UAV localization, they are expensive and have less practicality in real situations. In this paper a system consisting of a stereo camera embedded on a quadrotor UAV (QUAV) for indoor localization was proposed. The optical flow data from the stereo camera then are fused with attitude and acceleration data from our sensors to get better estimation of the quadrotor location. The quadrotor altitude is estimated using Scale Invariant Feature Transform (SIFT) Feature Stereo Matching in addition to the one computed using optical flow. To avoid latency due to computational time, image processing and the quadrotor control are processed threads and core allocation. The performance of our QUAV altitude estimation is better compared to single-camera embedded QUAVs due to the stereo camera triangulation, where it leads to better estimation of the x-y position using optical flow when fused together
Guest editorial : In Journal of networks, v.7 n.3
Networking of computing devices has been going through rapid evolution and thus continuing to be an ever expanding area of importance in recent years. New technologies, protocols, services and usage patterns have contributed to the major research interests in this area of computer science. The current special issue is an effort to bring forward some of these interesting developments that are being pursued by researchers at present in different parts of the globe. Our objective is to provide the readership with some insight into the latest innovations in computer networking through this. This Special Issue presents selected papers from the thirteenth conference of the series (ICCIT 2010) held during December 23-25, 2010 at the Ahsanullah University of Science and Technology. The first ICCIT was held in Dhaka, Bangladesh, in 1998. Since then the conference has grown to be one of the largest computer and IT related research conferences in the South Asian region, with participation of academics and researchers from many countries around the world. Starting in 2008 the proceedings of ICCIT are included in IEEExplore. In 2010, a total of 410 full papers were submitted to the conference of which 136 were accepted after reviews conducted by an international program committee comprising 81 members from 16 countries. This was tantamount to an acceptance rate of 33%. From these 136 papers, 14 highly ranked manuscripts were invited for this Special Issue. The authors were advised to enhance their papers significantly and submit them to undergo review for suitability of inclusion into this publication. Of those, eight papers survived the review process and have been selected for inclusion in this Special Issue. The authors of these papers represent academic and/or research institutions from Australia, Bangladesh, Japan, Korea and USA. These papers address issues concerning different domains of networks namely, optical fiber communication, wireless and interconnection networks, issues related to networking hardware and software and network mobility. The paper titled “Virtualization in Wireless Sensor Network: Challenges and Opportunities” argues in favor of bringing in different heterogeneous sensors under a common virtual framework so that the issues like flexibility, diversity, management and security can be handled practically. The authors Md. Motaharul Islam and Eui-Num Huh propose an architecture for sensor virtualization. They also present the current status and the challenges and opportunities for further research on the topic. The manuscript “Effect of Polarization Mode Dispersion on the BER Performance of Optical CDMA” deals with impact of polarization mode dispersion on the bit error rate performance of direct sequence optical code division multiple access. The authors, Md. Jahedul Islam and Md. Rafiqul Islam present an analytical approach toward determining the impact of different performance parameters. The authors show that the bit error rate performance improves significantly by the third order polarization mode dispersion than its first or second order counterparts. The authors Md. Shohrab Hossain, Mohammed Atiquzzaman and William Ivancic of the paper “Cost and Efficiency Analysis of NEMO Protocol Entities” present an analytical model for estimating the cost incurred by major mobility entities of a NEMO. The authors define a new metric for cost calculation in the process. Both the newly developed metric and the analytical model are likely to be useful to network engineers in estimating the resource requirement at the key entities while designing such a network. The article titled “A Highly Flexible LDPC Decoder using Hierarchical Quasi-Cyclic Matrix with Layered Permutation” deals with Low Density Parity Check decoders. The authors, Vikram Arkalgud Chandrasetty and Syed Mahfuzul Aziz propose a novel multi-level structured hierarchical matrix approach for generating codes of different lengths flexibly depending upon the requirement of the application. The manuscript “Analysis of Performance Limitations in Fiber Bragg Grating Based Optical Add-Drop Multiplexer due to Crosstalk” has been contributed by M. Mahiuddin and M. S. Islam. The paper proposes a new method of handling crosstalk with a fiber Bragg grating based optical add drop multiplexer (OADM). The authors show with an analytical model that different parameters improve using their proposed OADM. The paper “High Performance Hierarchical Torus Network Under Adverse Traffic Patterns” addresses issues related to hierarchical torus network (HTN) under adverse traffic patterns. The authors, M.M. Hafizur Rahman, Yukinori Sato, and Yasushi Inoguchi observe that dynamic communication performance of an HTN under adverse traffic conditions has not yet been addressed. The authors evaluate the performance of HTN for comparison with some other relevant networks. It is interesting to see that HTN outperforms these counterparts in terms of throughput and data transfer under adverse traffic. The manuscript titled “Dynamic Communication Performance Enhancement in Hierarchical Torus Network by Selection Algorithm” has been contributed by M.M. Hafizur Rahman, Yukinori Sato, and Yasushi Inoguchi. The authors introduce three simple adapting routing algorithms for efficient use of physical links and virtual channels in hierarchical torus network. The authors show that their approaches yield better performance for such networks. The final title “An Optimization Technique for Improved VoIP Performance over Wireless LAN” has been contributed by five authors, namely, Tamal Chakraborty, Atri Mukhopadhyay, Suman Bhunia, Iti Saha Misra and Salil K. Sanyal. The authors propose an optimization technique for configuring the parameters of the access points. In addition, they come up with an optimization mechanism in order to tune the threshold of active queue management system appropriately. Put together, the mechanisms improve the VoIP performance significantly under congestion. Finally, the Guest Editors would like to express their sincere gratitude to the 15 reviewers besides the guest editors themselves (Khalid M. Awan, Mukaddim Pathan, Ben Townsend, Morshed Chowdhury, Iftekhar Ahmad, Gour Karmakar, Shivali Goel, Hairulnizam Mahdin, Abdullah A Yusuf, Kashif Sattar, A.K.M. Azad, F. Rahman, Bahman Javadi, Abdelrahman Desoky, Lenin Mehedy) from several countries (Australia, Bangladesh, Japan, Pakistan, UK and USA) who have given immensely to this process. They have responded to the Guest Editors in the shortest possible time and dedicated their valuable time to ensure that the Special Issue contains high-quality papers with significant novelty and contributions
Big data architecture evolution : 2014 and beyond
This paper aims at developing the Big Data Architecture, and its relation with Analytics, Cloud Services as well as Business Intelligence. The chief aim from all mentioned is to enable the Enterprise Architecture and the Vision of an Organizational target to utilize all the data they are ingesting and regressing data for their short-term or long-terms analytical needs, while making sure that they are addressing during the design phase of such data architecture for both directly and indirectly related stakeholder. Since all stakeholders have their relative interests to utilize the transformed data-sets. This paper also identifies most of the Big Data Architecture, threat analysis within a Big Data System and Big Data Analytic Roadmaps, in terms of smaller components by conducting a gap-analysis that has significant importance as Baseline Big Data Architecture, targeting the end resultant Architectures, once the distillation process of main Big Data Architecture is completed by the Data architects
Growth, Nitrogen Uptake and Carbon Isotope Discrimination in Barley Genotypes Grown under Saline Conditions
The effect of different salinity levels of irrigation water (ECw range 1-12 dS/m) on dry matter yield, nitrogen uptake, fertilizer nitrogen use efficiency (%NUE), stomatal conductance and carbon isotope discrimination (Δ13C‰) in three barley genotypes originating from different geographic areas (Arabi.Abiad, Syria; Pk-30-136, Pakistan and WI-2291, Australia) was investigated in a pot experiment. An increase in salinity resulted in a decrease in Δ13C in all the genotypes. Increasing salinity reduced leaf stomatal conductance which was less pronounced in WI-2291 comparing to other genotypes. At high salinity level, the reduction in Δ13C corresponded to a considerable decrease in the ratio (Ci/Ca) of intercellular (Ci) and atmospheric (Ca) partial pressures of CO2 in all the genotypes indicating that such a decrease was mainly due to the stomatal closure. Moreover, since the reduction in dry matter yield in all the genotypes grown at 12 dS/m did not exceed 50% in comparison with their controls, the photosynthetic apparatus of all studied genotypes seemed to be quit tolerant to salinity. At the moderate salinity level (8 dS/m), the enhancement of leaf dry matter yield in the WI2291 genotype might have been due to positive nutritional effects of the salt as indicated by a significant increase in nitrogen uptake and NUE. Thus, the lower Ci/Ca ratio could result mainly from higher rates of photosynthetic capacity rather than stomatal closure. On the other hand, relationships between dry matter yield or NUE and Δ13C seemed to be depending on plant genotype, plant organ and salinity level. Based on growth, nutritional and Δ13C data, selection of barley genotypes for saline environments was affected by salinity level. Therefore, such a selection must be achieved for each salinity level under which the plants have been grown
Guest editorial : In Journal of networks, v.6 n.1
In recent years, networking of computing devices has been going through rapid evolution and thus continuing to be an ever expanding area of importance. Different technologies, protocols, services and usage patterns have contributed to the major research interests in this area of computer science. The current special issue is an effort to bring forward some of these interesting developments that are being pursued by researchers at present in different parts of the globe. Our objective is to provide the readership with some insight into the latest innovations in computer networking through this
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