bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of Ultrasonic-Assisted Extraction of Flavonoid Compounds and Antioxidants from Alfalfa Using Response Surface Method
Authors: Jing Chang-Liang , Dong Xiao-Fang , Tong Jian-Ming
Published: August 2015

Ultrasonic-assisted extraction (UAE) was used to extract flavonoid-enriched antioxidants from alfalfa aerial part. Response surface methodology (RSM), based on a four-factor, five-level central composite design (CCD), was employed to obtain the optimal extraction parameters, in which the flavonoid content was maximum and the antioxidant activity of the extracts was strongest. Radical scavenging capacity of the extracts, which represents the amounts of antioxidants in alfalfa, was determined by using 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) methods. The results showed good fit with the proposed models for the total flavonoid extraction (R2 = 0.9849), for the antioxidant extraction assayed by ABTS method (R2 = 0.9764), and by DPPH method (R2 = 0.9806). Optimized extraction conditions for total flavonoids was a ratio of liquid to solid of 57.16 mL/g, 62.33 °C, 57.08 min, and 52.14% ethanol. The optimal extraction parameters of extracts for the highest antioxidant activity by DPPH method was a ratio of liquid to solid 60.3 mL/g, 54.56 °C, 45.59 min, and 46.67% ethanol, and by ABTS assay was a ratio of liquid to solid 47.29 mL/g, 63.73 °C, 51.62 min, and 60% ethanol concentration. Our work offers optimal extraction conditions for total flavonoids and antioxidants from alfalfa.
Tracking Ecosystem Water Use Efficiency of Cropland by Exclusive Use of MODIS EVI Data
Authors: Tang Xuguang , Li Hengpeng , Griffis Tim , Xu Xibao , Ding Zhi , Liu Guihua
Published: August 2015

One of the most important linkages that couple terrestrial carbon and water cycles is ecosystem water use efficiency (WUE), which is relevant to the reasonable utilization of water resources and farming practices. Eddy covariance techniques provide an opportunity to monitor the variability in WUE and can be integrated with Moderate Resolution Imaging Spectroradiometer (MODIS) observations. Scaling up in situ observations from flux tower sites to large areas remains challenging and few studies have been reported on direct estimation of WUE from remotely-sensed data. This study examined the main environmental factors driving the variability in WUE of corn/soybean croplands, and revealed the prominent role of solar radiation and temperature. Time-series of MODIS-derived enhanced vegetation indices (EVI), which are proxies for the plant responses to environmental controls, were also strongly correlated with ecosystem WUE, thereby implying great potential for remote quantification. Further, both performance of the indirect MODIS-derived WUE from gross primary productivity (GPP) and evapotranspiration (ET), and the direct estimates by exclusive use of MODIS EVI data were evaluated using tower-based measurements. The results showed that ecosystem WUE were overpredicted at the beginning and ending of crop-growth periods and severely underestimated during the peak periods by the indirect estimates from MODIS products, which was mainly attributed to the error source from MODIS GPP. However, a simple empirical model that is solely based on MODIS EVI data performed rather well to capture the seasonal variations in WUE, especially for the growing periods of croplands. Independent validation at different sites indicates the method has potential for broad application.
Head Pose Estimation on Top of Haar-Like Face Detection: A Study Using the Kinect Sensor
Authors: Saeed Anwar , Al-Hamadi Ayoub , Ghoneim Ahmed
Published: August 2015

Head pose estimation is a crucial initial task for human face analysis, which is employed in several computer vision systems, such as: facial expression recognition, head gesture recognition, yawn detection, etc. In this work, we propose a frame-based approach to estimate the head pose on top of the Viola and Jones (VJ) Haar-like face detector. Several appearance and depth-based feature types are employed for the pose estimation, where comparisons between them in terms of accuracy and speed are presented. It is clearly shown through this work that using the depth data, we improve the accuracy of the head pose estimation. Additionally, we can spot positive detections, faces in profile views detected by the frontal model, that are wrongly cropped due to background disturbances. We introduce a new depth-based feature descriptor that provides competitive estimation results with a lower computation time. Evaluation on a benchmark Kinect database shows that the histogram of oriented gradients and the developed depth-based features are more distinctive for the head pose estimation, where they compare favorably to the current state-of-the-art approaches. Using a concatenation of the aforementioned feature types, we achieved a head pose estimation with average errors not exceeding 5:1; 4:6; 4:2 for pitch, yaw and roll angles, respectively.
Virological Failure in Two Patients with HIV-1 RNA Viral Loads >1,000,000 copies/ml Initiated on Elvitegravir/Cobicistat/Emtricitabine/Tenofovir Disoproxil Fumarate
Authors: Adams Jessica L , Byrne Dana , Pepe Rosalie , Gray Anastasia , Baxter John D
Published: August 2015

Very high baseline HIV-1 RNA viral loads require potent and robust antiretroviral regimens to achieve virological suppression. The coformulated single tablet regimen of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/COBI/FTC/TDF) is recommended by the US Department of Health and Human Services for the treatment of HIV-1 in treatment-naive adults and adolescents regardless of baseline CD4+ T-cell count and viral load. We report two cases of HIV-infected, treatment-naive patients, with baseline HIV-1 RNA viral loads >1,000,000 copies/ml who were initiated on the single tablet regimen EVG/COBI/FTC/TDF, but failed to attain viral load suppression and developed resistance to the components of EVG/ COBI/FTC/TDF.
Distributed Dynamic Resource Allocation for OFDMA-Based Cognitive Small Cell Networks Using a Regret-Matching Game Approach
Authors: Lai Wei-Sheng , Chang Tsung-Hui , Lee Ta-Sung
Published: August 2015

Game theoretical approaches have been used to develop distributed resource allocation technologies for cognitive heterogeneous networks. In this chapter, we present a novel distributed resource allocation strategy for cognitive small cell networks based on orthogonal frequency-division multiple access. In particular, we consider a heterogeneous network consisting of macrocell networks overlaid with cognitive small cells that opportunistically access the available spectrum. We focus on a regret-matching game approach, aiming at maximizing the total throughput of the small cell network subject to cross-tier interference and quality of service (QoS) constraints. The regret-matching game approach exploits a regret procedure to learn the optimal resource allocation strategy from the regrets of the actions of cognitive users. Furthermore, the regret-matching game approach is extended to the joint resource allocation and user admission control problem. Numerical results are presented to demonstrate the effectiveness of the proposed regre-matching approaches.
Game Theoretic Approaches for Wireless Cooperative Content-Sharing
Authors: Militano Leonardo , Iera Antonio , Scarcello Francesco , Molinaro Antonella , Araniti Giuseppe
Published: August 2015

This chapter provides an overview of game theoretic solutions in a wireless application of particular interest for multimedia and social interactions in modern telecommunication systems. In particular, coalitional games, bargaining solutions and fairness and stability issues will be investigated within wireless cooperative content-sharing. According to this paradigm, users download portions of data of common interest over long-range cellular links while exchanging the downloaded portions over short-range radio links. Expected benefits, which are natural incentives to cooperation, may be in terms of content price, energy consumption, and transfer delay reduction. Significant research activity has been conducted to design strategies that simultaneously exploit the multiple radio interfaces of modern wireless devices and maximize the gain. A valid solution for the cooperative content-sharing application should be based on fairness in the utility distribution among the involved nodes which can be eased by exploiting the game theoretic approaches presented in this chapter.
Game Theoretic Analysis for Cooperative Video Transmission over Heterogeneous Devices
Authors: Ji Wen , Chen Bo-Wei , Chen Yiqiang , Kang Shaojie , Zhang Shuili
Published: August 2015

This chapter presents a mechanism for cooperative video transmission based on game theory for heterogeneous devices during broadcasting. Broadcasting is a multipoint delivery of transmission that sends data from a source to multiple destinations. The terminal is involved in cooperative transmission when the station broadcasts video data. To enhance performance, the heterogeneity and forwarding capabilities should be considered. This work studies power control and allocation in a collaborative transmission based on game theory, which provides an effective strategy when network resources are limited. First, a novel power-allocation model of the base station (BS) based on noncooperative game theory and bidding is presented in this study. Additionally, we also propose a utility function of Signal-to-Noise Ratios (SNRs) along with Signal-to-Interference Ratio (SIRs). Subsequently, based on such noncooperative game theory with a utility function, the model of the power distribution of terminals in cooperative transmission can be built. Experiments on the System-in-the-Loop (SITL) mode in OPNETs have proven the correctness of the designed model and superiority, verifying the effectiveness of the proposed power-control idea.
Multiband Antenna for Modern Wireless Communication
Authors: Elamin Nassrin , Rahman Tharek
Published: August 2015

Wireless technology lately became subjected to the rapid enormous changes in frequency allocation, policies and procedures of operations, and techniques in order to enhance the performance of the wireless system as whole. A lot of wired applications are converted into wireless, for example wired LAN is turned into a wireless, which due to the huge sophisticated researches. Currently due to the advanced of the integrated technology, engineers are able to fit many diversified applications working at different frequencies in one wireless device. Consequently an increased demand for multiple antennas covering different wireless communication bands on the same platform increased extremely.
Reconfigurable Antennas for Cognitive Radio
Authors: Nguyen Trong Duc , Duroc Yvan , Vuong Tan-Phu
Published: August 2015

With the development of the cognitive radio, that is a system (transceiver) aware of its own operational capabilities and needs which aims at a more efficient use of radio resources (e.g., more universal solution for the co-existence of multiple radio standards, but also limitation of electromagnetic radiations), the antennas with reconfiguration capabilities will become unavoidable. This chapter describes the different types of existing reconfigurable antennas and related approaches allowing the reconfiguration. The presentation relies on many examples from the literature and an example of designing a complete system of reconfigurable antenna frequency is finally detailed.
Recent Trends for Interference Mitigation in Multi-Antenna Wireless Systems
Authors: Abu-Ella Omar Ali , Elmusrati Mohammed Salem
Published: August 2015

In this chapter we discuss the general techniques of multi-antenna systems. Then, we delve to describe four recent trends in interference mitigation technologies that will change the design of the future 4G and beyond (5G) of mobile and wireless communication systems. Particularly, we consider the coordinated multi-point MIMO systems, smart terminal devices techniques, millimeter-wave communications and massive MIMO systems. We discuss the fundamental concepts of those new approaches, along with their advantages, and the challenges facing such technologies. Even though the references list of this chapter is not anticipated to be exhaustive, the cited articles and also the references therein should be good sources of further reading to start with.
Security and Privacy in Next Generation Networks and Services
Authors: Kotzanikolaou Panayiotis
Published: August 2015

The deployment of Next Generation networks such as wireless broadband networks and wireless ad hoc networks, has lead to the proliferation of new mobile, pervasive and ubiquitous services, such as online social networks, location based services or cloud computing services. These new network paradigms and services raise serious privacy concerns. This chapter reviews security and privacy issues in Next Generation (NG) networking. Intitially, a general categorization of various popular NG networks and services is presented. Then, the security and privacy threats identified for each category are examined, along with a brief review of the related security requirements and mitigation strategies described in the recent literature.
Firefox OS Ecosystem
Authors: Janczukowicz Ewa , Bouabdallah Ahmed , Braud Arnaud , Tuffin Stéphane , Bonnin Jean-Marie
Published: August 2015

Firefox OS is an operating system for mobile devices. It is developed by Mozilla and is based on web technologies. Developed applications are therefore not tied to a given type of hardware. Mozilla works on standardisation of Web APIs, so that the device hardware could be accessed more easily. It also introduced its sign-in system for the Web and furthermore, it wants to redefine the way payments work for mobile applications. Firefox OS is not directly competing with Android and iOS, although it has some common target markets with Android. It could be an opportunity to weaken the iOS and Android duopoly. For now it targets users that don't have smartphones yet and is mostly used on low-end devices. The biggest challenge of Firefox OS is to assure a stable position in the mobile OS ecosystem and to get a large volume of users. Mozilla has an ambition to improve the web and make the web the platform. However developing the Firefox OS and ensuring its important place on the market is difficult because of technological and business limits that will be discussed in this chapter.
Mobile-Fixed Integration for Next-Generation Mobile Network
Authors: Cortés-Polo David , González-Sánchez Jose-Luis , Rodríguez-Pérez Francisco J. , Carmona-Murillo Javier
Published: August 2015

In recent years, the growth the in number of heterogeneous interconnected systems, as well as the emergence of new requirements in applications and services are progressively changing the original simplicity and transparency of the Internet architecture. When this architecture was designed, the main goal was to interconnect stationary host. Therefore, the appearance of mobile communications has made necessary to adapt traditional protocols in order to accommodate mobile users. This implies a new interaction between the mobile network and the fixed access network. This chapter describes the main IP mobility protocols and presents a novel classification, which relates the integration of the mobility protocol with the access network. The chapter also presents analytical models to evaluate the registration updates cost and the packet loss rate of the classified protocols.
Mobility in Healthcare
Authors: Gürsel Güney
Published: August 2015

Mobility is the blossoming technology of our era. Mobile devices, especially smart phones, tablets, phablets are becoming common, and they are being a part of us as we carry all the time with us. Business discovered the easy-to-reach-customer facility of mobility and companies focus on this area. Scientific research focused on this area as well. Using the facilities provided with all the time with us mobile devices, especially healthcare can gain tremendous advances and have already done in some applications. Remote healthcare, decreased costs, advanced healthcare access, prioritizing the patients, can be given as examples to the advances that have been gained. As the mobile healthcare applications becoming common, there exists a danger of abuse and misuse. The need for regulations has emerged. The purpose of this study is to give basic information and vision about the usage of mobility in medical domain to ease healthcare and make it more effective. The mobile technologies used in the healthcare information systems, together with the challenges, problems and regulations, is explained.
Advances in QoS/E Characterization and Prediction for Next Generation Mobile Communication Systems
Authors: Pitas Charalampos N. , Fertis Apostolos G. , Charilas Dimitris E. , Panagopoulos Athanasios D.
Published: August 2015

The scope of this work is to present a holistic approach in quality of service (QoS) and quality of experience (QoE) characterization and prediction in modern mobile communication networks. Analytically, multi radio access technologies have been deployed in order to deliver mobile services to quality demanded consumers. Quality of Experience (QoE) parameters describe the End-to-End (E2E) quality as experienced by the mobile users. These parameters are difficult to be measured and quantified. System Quality of Service (SQoS) parameters are metrics that are closely related to the network status, and defined from the viewpoint of the service provider rather than the service user. Moreover, E2E Service Quality of Service (ESQoS) parameters describe the QoS of the services and they are obtained directly from the QoE parameters by mapping them into parameters more relevant to network operators, service providers and mobile users. A useful technique for mobile network planning and optimization is to build reliable quality estimation models for mobile voice and video telephony service.
A Review of Automated Methodologies for the Detection of Epileptic Episodes Using Long-Term EEG Signals
Authors: Tsiouris Kostas M. , Tzallas Alexandros T. , Markoula Sofia , Koutsouris Dimitris , Konitsiotis Spiros , Fotiadis Dimitrios I.
Published: August 2015

Epilepsy is a chronic neurological condition caused by abnormal electrical activity of the human brain that affects up to 1% of the global population. Since seizures may occur at any time, long-term EEG recordings are more suitable to record ictal activity. To assist the inspection process various automated seizure detection methodologies have been reported demonstrating high performance. In this chapter the majority of such long-term EEG signal processing techniques and methods, used in the seizure detection domain, are presented. Emphasis is particularly given on providing a complete overview of the wide variety of methodologies from the last few years, which were evaluated using two well-known public EEG databases consisting of long-term scalp and intracranial EEG recordings. The purpose of this chapter is to provide an evaluation of the methods' performance under a common reference dataset to assess their suitability for implantable or ambulatory seizure detection devices.
Contemporary Heart Failure Treatment Based on Improved Knowledge and Personalized Care of Comorbidities
Authors: Giokas Kostas , Tsirmpas Charalampos , Anastasiou Athanasios , Iliopoulou Dimitra , Costarides Vassilia , Koutsouris Dimitris
Published: August 2015

Chronic diseases are the leading cause of mortality and morbidity. A significant contribution to the burden of chronic diseases is the concurrence of co-morbidities. Heart failure (HF) is a complex, chronic medical condition frequently associated with co-morbidities. The current care approach for HF patients with co-morbidities is neither capable to deliver personalised care nor to halt the on-going increase of its socio-economic burden. Our approach aims to improve the complete care process for HF patients and related co-morbidities to improve outcome and quality of life. This will be achieved by the proposed standardised yet personalised patient-oriented ICT system that supports evidence-based clinical decision making as well as interaction and communication between all stakeholders with focus on the patients and their relatives to improve self-management. We propose that such a system should be build upon a novel European-wide data standard for clinical input and outcome and that it should facilitate decision making and outcome tracking by new collective intelligence algorithms.
Trends and New Advances on Wearable and Mobile Technologies for Parkinson's Disease Monitoring and Assessment of Motor Symptoms
Authors: Cancela Jorge , Pastorino Matteo , Waldmeyer Maria Teresa Arredondo
Published: August 2015

The aim of this work is to analyze the trends and new advances carried out in the last decades in the field of Parkinson's disease monitoring and management and more specifically regarding wearable and mobile technologies. The challenges of such technologies is to monitor, to assess and to manage the full range of PD symptoms through monitoring and testing routines while not hampering the patient's daily activities, identifying the correlation between the different dimensions affecting the severity of symptoms and the evolution of the disease and enabling the clinician to manage more efficiently the patient by providing timely indications on the effectiveness of the therapy and suggestions on therapy changes.
Integrated System for Continuous Monitoring of COPD
Authors: Giokas Kostas , Iliopoulou Dimitra , Makris Ioannis , Koutsouris Dimitris
Published: August 2015

Chronic Obstructive Pulmonary Disease (COPD) is a progressive pulmonary disease characterized by reduction in airflow and is not fully reversible. COPD is the major cause of mortality and increased levels of disability, particularly in the elderly. Symptoms vary among individuals and include breathlessness, dyspnea, abnormal sputum and chronic cough. Exposure to tobacco smoke is by far the most important risk factor in the development of COPD and is associated with high levels of morbidity and mortality. In this chapter the authors will present a system for the integrated care of COPD focusing on prevention and intervention.
Computational Intelligence Paradigms
Authors: El-Alfy El-Sayed M. , Awad Wasan
Published: August 2015

The evolution of communication networks and information systems, to support wireless access, cloud and grid computing, and big data, provides great business opportunities. However, it also generates a new trend of sophisticated network threats and offers several challenges in securing information and systems confidentiality, integrity and availability. The traditional techniques used by security experts are mostly static and lack the much needed characteristics of adaptation and self-organization, computational efficiency and error resilience to deal with evolving attacks. The inherent characteristics of computational intelligence (CI) paradigms provide a promising alternative that has gained popularity resulting in significant applications in information security. There is a plethora of CI paradigms commonly used in this domain including artificial neural networks, evolutionary computing, fuzzy systems, and swarm intelligence. This chapter provides an overview of the widely-recognized CI paradigms and shades the light on some of their potential applications in information security.
Automated Design of Stream Ciphers Using GADS
Authors: Awad Wasan , Al Hiddi Amal M.
Published: August 2015

The main objective of this chapter is to propose a new effective algorithm to design stream cipher systems automatically using simulated annealing algorithm and genetic programming with a different method for representing the genetic programming population individuals. Usually the individual programs represented as LISP expressions; in the proposed method the programs are represented as strings of integers representing the individual program syntactic rule numbers. Genetic programming with this representation method is called genetic algorithm for developing software (GADS). The performance of the proposed algorithm will be studied by applying different genetic methods and parameters. Furthermore, it will be compared with other representation methods such as LISP expression.
Development of an Indigenous Impedance Tube
Authors: Tan Wei Hong , Ahmad Rosmaini , Zunaidi Nur Hafizah , Daud Ruslizam , Cheng E.M.
Published: August 2015

Fabrication of an impedance tube for measuring sound absorption coefficient is presented in this paper. Transfer-function method is chosen for the sound absorption analysis. The impedance tube is designed and fabricated in accordance with ISO 10534-2. The tube is made from brass with diameter of 114.3 mm and length of 1.42 m. It is designed for the frequency range 60 Hz to 1800Hz. Three microphone positions are installed to achieve the frequency range with a single tube. The theoretical background of transfer-function method between two microphones is discussed. Initially, impedance tube is characterized by the measurement without testing material in the tube. Micro-perforated panel (MPP) with 50 mm and 100 mm of cavity depth are used for measurement. The sound absorption coefficient measurement of the MPP is compared with theory and good agreement is achieved. Various problems related to design and construction is addressed and the optimal configuration is presented.
Nonlinear Dynamic Analysis of Cantilever Beam Using POD Based Reduced Order Model
Authors: Atul Shankar Kulkarni , Pandey Manoj
Published: August 2015

In this paper, a reduced order model is obtained for nonlinear dynamic analysis of a cantilever beam. Nonlinearity in the system is basically due to large deformation. A reduced order model is an efficient method to formulate low order dynamical model which can be obtained from data obtained from numerical technique such as finite element method (FEM). Nonlinear dynamical models are complex with large number of degrees of freedom and hence, are computationally intensive. With formulation of reduced order models (i.e. Macromodels) number of degrees of freedom are reduced to fewer degrees of freedom by using projection based method like Galerkin’s projection, so as to make system computationally faster and cost effective. These macromodels are obtained by extracting global basis functions from fully meshed model runs. Macromodels are generated using technique called proper orthogonal decomposition (POD) which gives good linear fit for the nonlinear systems. Using POD based macromodel, response of system can be computed using fewer modes instead of considering all modes of system. Macromodel is generated to obtain the response of cantilever beam with large deformation and hence, simulation time is reduced by factor of 90 approximately with error of order of 10-4. Further, method of POD based reduced order model is aplied to beam with different loading conditions to check the robustness of the macromodel. POD based macromodel response gives good agreement with FEA model response for a cantilever beam.
The Effect of Mesh Size And Frictional Force on Simulation of Aluminium Honeycomb Under Quasi-Static Loading
Authors: Pokaad Alif Zulfakar , Said Md Radzai
Published: August 2015

This paper focuses on the works to model the aluminium honeycomb with the effect of meshing size that implemented into a shell body of the honeycomb and frictional force that introduced into an interaction between the honeycomb and rigid plates. The model is performed by using ABAQUS 6.12 in the explicit environment. The honeycomb with 0.0127 m cell size is modelled and three types of mesh size which are 3 mm, 1 mm and 0.8 mm are analysed based on buckling mode and load-displacement characteristics. No friction coefficient is applied during simulation. From this simulation, 1 mm meshing size is the optimize value where the load-compression pattern graph is almost similar like the experimental result compared with others meshing size. But the buckling mode is slightly different compared with the experimental result where the bottom part of honeycomb made the contract or negative expand behaviour. In order to avoid this behaviour, the friction coefficient is introduced between the honeycomb surface and rigid plates surface. Two values of friction coefficient are tested which are 0.1 and 0.3. The findings is the frictional coefficient 0.3 and meshing size 1 mm are optimized values that can avoid the contract behaviour and the result of buckling mode is similar with the experimental result.
Study of PWHT of EN-WB 36 Welded Material for High Pressure Application in Power Plants
Authors: Sarwar Muhammad , Mohd Amin Abd Majid
Published: August 2015

The heat-resistant, copper-alloyed ferritic steel 15NiCuMoNb5 (EN-WB36, material number 1.6368) has been widely used in European nuclear and conventional power plants for decades for feed water system. This widespread application is due to the toughness and strength, caused by the precipitation of copper, that are exhibited even at elevated temperatures which other fine-grained structural steels have at room temperature. The common problem faced on the construction sites is the embrittlement due to Cu-rich precipitates and the high hardness in welded joints that affect the weld quality and the premature joint failure can occur in service. Weld hardness has close relationship with the strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. The aim of this study is to see the impact of the impact of post weld heat treatment (PWHT) on the welded joints of WB 36 and find the optimal PWHT conditions that will produce the required hardness to overcome the problem of embrittlement in the welded material. Samples of different thicknesses were welded, keeping all the parameters same, PWHT carried out with induction heating equipment, joints were radiographed for any defect, macro-etched to confirm complete fusion and joint free from crack, and the hardness values were measured in base metals, heat affected zones and weld metal. It was found out that the embrittlement of WB-36, due to Cu-rich precipitates and high hardness, in welded joints can be brought into the lower and safer limits by applying PWHT at 570 °C for 1 hour min. This, for sure, will reduce the risk of premature joint failure and will have, comparatively, safer weld joint.
Synthesis of LiCoxMn2-xO4 by Low Temperature Solid-State Reaction for Cathode Material
Authors: Purwaningsih Dyah , Roto Roto , Narsito Narsito , Sutrisno Hari
Published: August 2015

LiCoxMn2-xO4 can serve as one of the main candidates for cathode materials for lithium batteries since they are abundant, low cost and environmentally friendly. This study aims to study the synthesis of LiCoxMn2-xO4 by low temperature solid-state reaction and its microstructure determination. Attention is paid more to the mole ratio of Co/Mn in LiCoxMn2-xO4. The compound was characterized by XRD, SEM-EDX, and BET while the analysis of LiCoxMn2-xO4 microstructure was carried out by Direct Method using winPLOTR package program and Diamond using XRD data. The series of LiCoxMn2-xO4 have well–developed cubic crystal structure with Fd3m phase, and the increase in the dopant does not change its structure. The lattice parameters and cell volumes of LiCoxMn2-xO4 tend to decrease with the increase in x values
Texture Analysis of the Hot Rolling Austenitic Cr-Ni Steel Using Neutron Diffraction Method
Authors: Priyanto Tri Hardi , Effendi Nurdin , Parikin Parikin
Published: August 2015

Synthesis of austenite stainless steel using extracted minerals from Indonesian mines has been carried out. It is namely A2 steel. The main raw material of making non standard steel A2 is granular scrap iron, nickel, iron-chromium, iron-manganese, and iron-silicon. It is obtained from non standards. A component of A2 steel consists of 15,42%Cr, 25,01%Ni, 0,32%Mn, 0,96%Si and 0,34%C with impurities of 0,039%V and 0,051%Cu. Characterization using neutron diffraction technique shows the first four Bragg peaks of (111), (200), (220) and (311). A machining process was performed to make a plat from ingot. After the machining process, intensities and FWHM of the first two Bragg peaks of (111) and (200) are quite the same. But the intensity of the peaks (220) and (311) changes. It is calculated that for (220)peak the decreasing intensity about 51.6% and increasing FWHM about 0.14%, whereas for (311) peak the intensity increase about 40.2% and the FWHM decrease about 3%. Furthermore, the material obtained from the machining process is used as a reference to the condition of the material without rolling. After being subjected to rolling up to 70% thickness reduction, crystal orientation changes from highest intensity with a sequence of (200), (111) and (220) to (220) (111) and (200) with highest increasing intensity about 2.25 times at (220). Quantitative analysis of texture after the rolling process is shown in pole figures of (111), (200) and (220). It is characterized that crystals are oriented mainly to {110} <113>, texture index is 1.0671.
Development of Geopolymer from Fly Ash and Metallurgical Slag
Authors: Walmiki Samadhia Tjokorde , Muan Nurhidayati
Published: August 2015

Geopolymers, which areinorganic polymers consisting largely of three-dimensional Al-Si-O networkformed by reactions between aluminosilicate solids and concentrated alkalisolutions, are gaining recognition as environmentally friendly engineeringmaterials. As a replacement for ordinary Portland cement (OPC), geopolymerconsumes much less energy to produce, and may be synthesized from various solidinorganic waste materials. This work describes the synthesis of geopolymerswhich combines two waste materials as aluminosilicate precursors: an ASTM ClassC coal fly ash from the Paiton powerplant, and Fe-rich metallurgical slag fromKratakau Steel. To study the effects of the reactant mixture composition, asimplex centroid experiment is undertaken with fly ash and slag as its majorcomponents, and level of addition of sodium silicate as the independentvariable. The highest slag to ash mass ratio is set at 50%. The solidaluminosilicates and sodium silicate are mixed with 10 M KOH solution at a massratio of 2.8. The mixture is processed in a planetary mixer to form a smoothpaste, which is then cast into specimens for the measurement of compressivestrength in a universal uniaxial load tester after a 1-week period of curing atroom temperature. The measured compressive strengths of all geopolymer pastesamples are lower than that of OPC, anddecreases with increasing slag proportion. Addition of Sodium silicateincreases the strength due to decreased porosity. Despite the highertheoretical reactivity of the slag compared to the Paiton fly ash, estimatedfrom their degrees of network depolymerization, the addition of slag reducesthe geopolymer mortar compressive strength. It is hypothesized that therelatively coarse size of the slag particles offsets its higher reactivity.
Preparation of Chitosan-Alginate/PES Pervaporation Membranes for Bioethanol Dehydration
Authors: Pratiwi Mumpuni Asih , Sudrajat Ronny Windu , Sutanti Sri , Susanto Heru
Published: August 2015

In the last decade pervaporation membrane has become an antractive dehydration processs for azeotropic ethanol-water mixture. In this paper, chitosan-alginate/polyethersulfone (PES) composite membranes were prepared (by coating method) characterized as pervaporation membranes. The composite membranes were then examined to purify ethanol-water mixture. The characterization included degree of swelling both in water and ethanol, permeability measurement, surface morphology (by SEM) and surface chemistry (by FTIR). The results show that the increase in concentration of coating solution increases the degree of swelling in the water on the one hand, whereas the permeability and the degree of swelling in the ethanol decreases on the other hand. The highest permeability was obtained for the composite membrane prepared from a coating solution concentration of 1% with the ratio of chitosan to alginate was 0,33. The surface chemistry shows that the increase in concentration of chitosan - alginate solution increases the intensity of a specific wave number of C-O and C-N groups. Surface morphology indicates that the PES membrane surface is clearly covered by chitosan - alginate mixture. Performance examination demonstrates that the composite membrane prepared by 3% a coating solution (with the ratio of chitosan to alginate 3) can increase the bioethanol concentration from 95.5% to 99.6%.
The Effect of Sandblasting and Electropolishing on the Surface Roughness and Corrosion Rate of AISI 316L Stainless Steel
Authors: Suyitno Suyitno , Ishak Ishak , Dewo P. , Dharmastiti R. , Magetsari R. , Salim U.A. , Hidayat L.
Published: August 2015

The aim of this work is to investigate the effect of sandblasting and electropolishing on roughness and corrosion rate of AISI 316L stainless steel. The equipment used was sandblasting machine with a working pressure of 5-7 kg/cm2 with a duration of 10 minutes. The silica sand was used with size of 500-800 μm. The equipment used in the electropolishing process is the DC power supply with a maximum output of 2x100A. Anode and cathode material were AISI 316L stainless steel. Electrolyte solution consisted of 96% mass fraction of sulfuric acid and 85% mass fraction of phosphoric acid with a ratio of 1. The parameters used in the electropolish process were voltage, electrodes distance and electropolishing duration process. The combination of sandblasting and electropolishing cause the decrease in surface roughness by more than 28 times, from 3.17 to 0.11 μm. The decrease in the rate of corrosion on specimens that have been treated sandblasting and electropolishing by 37%. The optimum parameters for testing surface roughness and corrosion rate contained in the sandblasting process electropolishing for 10 minutes with a distance of 1 cm, duration 20 minutes and voltage 8V.
Study on Morphology of Electrospun SiOC Fibers
Authors: Setiawan Jan , Pribadi Slamet , Pranjono Pranjono , Poertadji Suhardjo , Sigit Sigit
Published: August 2015

Polycarbosilane (PCS) solution was used to form PCS fibers by electrospinning and curing them by thermal process. The cured PCS fibers were then pyrolized under inert atmosphere to obtain silicon oxycarbide (SiOC) fibers. The PCS solution contained 1.2 g/mL PCS with 30% N, N-dimethylformamide (DMF)/70% toluene. The needle inner diameters used for spinning were 0.5 and 0.3 mm and variation for the applied voltage were 10, 12 and 14 kV. The electrospun PCS fibers were cured at 200°C in oxygen atmosphere for 1 hour and then pyrolyzed at 1000°C in inert atmosphere for 1 hour. Nonwoven SiOC fibers diameter ranging between 3 to 8 µm were analyzed by SEM and EDS. The oxygen embodied on the surface of cured PCS fibers arising during the curing process resulted in the SiOC fibers with larger diameters. Rapid solvent evaporation during the pyrolysis caused the SiOC fibers to have ribbon-shapes.
Physical Properties and Photocatalytic Activity of Fe- and Co-Doped ZnO Nanoparticles Synthesized via Surfactant Modified Co-Precipitation
Authors: Noorhidayati Annisa , Adriani Siti , Saleh Rosari
Published: August 2015

Fe- and Co-doped ZnO with various doping concentrations have been synthesized by co-precipitation method in the presence of sodium dodecyl sulfate as anionic surfactant. The obtained sample powders were characterized by X-ray diffraction, Fourier transform infrared absorption, UV-visible diffuse reflectance spectroscopy, electron spin resonance spectroscopy and Brunauer-Emmet-Teller (BET) method. The photocatalytic activity was evaluated by observing the decolorization of methylene blue under UV light irradiation. The results revealed that the addition of a dopant atom significantly enhanced the photocatalytic activity.
Fabrication of Carbon Nanomaterial Using Arc-Discharge in Liquid Method for Battery Application
Authors: Anwar Miftahul , Argawan Panji Rofa , Cahyono Sukmaji Indro , Saraswati Teguh Endah , Purwanto Agus , Nizam Muhammad
Published: August 2015

This work aims to fabricate carbon-based nanomaterial using arc-discharge in liquid which is much simple and cheap compared to other techniques i.e., CVD, laser vaporization, etc. The experiment were performed using intermediate DC power supply (1300 W) to produce arc, and commercial graphite pencils (with 5 mm diameter) as negative and positive electrodes. Deionized water was used as heat absorber. The result shows that arc discharge in deionized water could effectively produce carbon nanomaterial (i.e., graphene and CNT). In adddition, finite element method-based simulation of different intercalating process of Li-ion to different shape of anode i.e., bulk and phorous anode materials for battery application is also presented in order to provide support for design of Li-ion battery based on carbon nanomaterial.
Photocatalytic Decolorization of Malachite Green in the Presence of Fe3O4/TiO2/CuO Nanocomposites
Authors: Arifin Sarah A. , Jalaludin Shofianina , Saleh Rosari
Published: August 2015

Fe3O4/TiO2/CuO nanocomposites have been synthesized by sol-gel method and further used as photocatalyst for decolorization of malachite green from aqueous system under UV and visible light irradiation. X-ray diffraction confirmed the phase purity and crystallinity of nanocomposites. From UV-visible spectroscopy measurements it is found that the absorption peak of TiO2 nanoparticles is shifted towards longer wavelength after formation of nanocomposites indicating a modification of bandgap. The photocatalytic activity of TiO2 nanoparticles was enhanced by hybridization under visible light irradiation. The photodegradation of malachite green was significantly reduced by the addition of tert-butyl alcohol indicated that •OH radicals played an important role in the photocatalytic mechanism.
Numerical Solutions to Fast Transient Pipe Flow Problems
Authors: Mungkasi Sudi , Prasetyadi Andreas , Sambada F.A.R.
Published: August 2015

We promote a finite volume method to solve a water hammer problem numerically. This problem is of the type of fast transient pipe flow. The mathematical model governing the problem is a system of two simultaneous partial differential equations. As the system is hyperbolic, our choice of numerical method is appropriate. In particular, we consider water flows through a pipe from a pressurized water tank at one end to a valve at the other end. We want to know the pressure and velocity profile in the pipe when the valve closes as a function of time. We find that the finite volume method is very robust to solve the problem.
Longitudinal Profiles of Atom Laser Propagation in a Cigar-Shaped Trap
Authors: Prayitno Teguh Budi , Widyanirmala Widyanirmala , Belfaqih Idrus Husin , Sutantyo T.E.K. , Astra I. Made
Published: August 2015

Focusing on the cigar-shaped trap model, we provide longitudinal profiles of a weakly outcoupled atom laser propagation both inside and outside the Bose-Einstein condensate regions. The propagation itself is generally represented by inhomogeneous Schrödinger equation which is derived from a set of Gross-Pitaevskii equations by applying the available conditions. We also show that by imposing boundary condition and using quantum oscillator model, energy of the outcoupled atom laser outside the Bose-Einstein condensate region is quantized while there is no analytical solution for the propagation of the outcoupled atom laser inside the Bose-Einstein condensate region.
The Effect of Addition of Indigenous Silica Powder from Lampung on the Concrete Performance after 1 Year Curing Time
Authors: Wismogroho Agus Sukarto , Widayatno Wahyu Bambang , Sudiro Toto , Aryanto Didik
Published: August 2015

In the present study, indigenous silica powder from Lampung was used as an additive in concrete mixture to investigate the effect of its addition on the concrete performance. The silica powder was pre-treated using planetary ball mill for 1 and 130 hours to obtain silica particle size of 10 and 2 microns, respectively. The obtained silica powder was then mixed with the concrete mixture and was cured for 1 year before further test. The analysis of hydration reaction between Portland cement and 20wt% silica powder showed that 30-50wt% calcium hydroxide was significantly consumed after curing for 1 year. Particle size reduction of silica powder increased its reactivity by 25-40%. The bending strength of cured sample was lower than that of standard sample. Microstructure and composition analysis showed the existence of alkali elements which can improve the possibility for the alkali silica reaction to occur.
Utilization of Fly Ash for a Support Layer of Pervaporation Membrane
Authors: Apriyanti Eny , Subekti Sri , Pratiwi Mumpuni Asih , Widiasa I. Nyoman , Susanto Heru
Published: August 2015

Fly ash is a byproduct of coal combustion, which has not maximally been utilized. In this paper, fly ash is used for a support layer of pervaporation membrane. Initially fly ash was screened by using either 100 or 200 mesh sieve filter. A paste mixture of fly ash, alumina, kaolin and other additives was prepared and molded with different pressures into a flat membrane support. The resulting membrane supports were characterized intern of mechanical property, surface morphology (by scanning electron microscope) and crystallinity (by X-ray Diffraction). The results show that the pressure used for the molding process as well as calcination process has an influence on the resulting membrane support characteristics.
Hot and Cold of Pressing Effect on ECAP-Parallel Channel Composite Based on Al/ANF Material
Authors: Pramono Agus , Kommel Lembit , Kollo Lauri , Veinthal Renno
Published: August 2015

A new Severe Plastic Deformation (SPD) technique namely Equal Channel Angular Pressing with Parallel Channels (ECAP-PC) was developed to improve the performance of traditional ECAP. Traditional ECAP produces a gross distortion at both ends during the process. Thus, it resulted in high cost process, because it can cause waste materials that have been estimated from 30% to 50%. To overcome the problem, an alternative procedure was developed in which the ECAP was conducted using two parallel channels, the materials used AA1070 and AA6061 powder with Alumina Nano-Fiber (ANF) as reinforcement. Mechanical properties and Scanning Electron Microscope (SEM) were observed in room temperature pressure and 400OC heating pressure. Both results were compared to determine the effect of temperature on each process. The result was that at 400OC temperature pressure, the hardness generated more uniform with hardness average reached 69.3 and 94.52 HV10 and at room temperature pressure, the hardness generated less uniform with an average 30.1 and 73.6 HV10. In hot pressure there was not any micro-crack, but in room temperature pressure there were some micro-crack.
High Temperature Oxidation of the Hot Rolled ZrNbMoGe Alloy for Fuel Cladding Material of Pressurized Water Reactor
Authors: Bandriyana Bandriyana , Rivai A.K. , Prajitno J.H. , Dimyati A.
Published: August 2015

The Zr-2.5Nb-0.5Mo-0.1Ge alloy were developed for application as fuel cladding material in an advanced Pressurized Water Reactor (PWR) with higher burn-up at higher service temperature. Oxidation behaviour of the alloy at high temperature similar to condition related to the operating with Lost of Cooling Accident (LOCA) conditions was investigated. The sample ingot was synthesized in an arc melting furnace followed by hot rolling at 850 °C down to 3 mm of thickness. Each one alloy ingot and one alloy sheet were subjected to the high temperature oxidation test in the Magnetic Suspension Balance (MSB) at 500 °C. Light optical microscope (LIOM) and Scanning Electron Microscope (SEM) equipped with X-ray Diffraction Spectroscopy (EDS) were used to characterize the microstructure of the oxide layer. The Vickers hardness tester was used to evaluate the hardness of the alloy matrix before and after oxidation processes. The results concluded that both samples showed oxidation rate characteristic which follows the parabolic phenomenon. However the hot rolled sample had lower rate. The oxide layer was indicated as ZrO2 .