bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of polycyclic aromatic hydrocarbons molecular diagnostic ratios as a source identification tool - case study
Authors: Janoszka Katarzyna , Klyta Justyna , Laks Łukasz , Słaby Krzysztof
Published: December 2018

Levoglucosan (LG) and Polycyclic Aromatic Hydrocarbons (PAHs) are organic substances emitted from variety of anthropogenic sources, mainly as a result of incomplete combustion or pyrolysis of organic material. The seasonality of PAHs emissions is a well demonstrated fact, observed in most monitoring studies, where PAHs air concentrations in winter are much higher than their respective in the summer, due to seasonally variable emission sources. Various techniques have been proposed as ideal source identification (or apportionment) tools, and much debate exists in scientific literature about the effectiveness of the proposed methodologies. The most common methodology is the use of molecular diagnostic ratios (MDRs). Based on the annual measurement campaign in rural site located on South Poland, were levoglucose and PAHs were analyzed, the MDRs were determined. The results showed that the combustion processes of solid fuels, including biomass, are mainly responsible for air quality.
Wetting properties of aqueous short-chain alcohols’ solutions
Authors: Mizerski Andrzej
Published: December 2018

The article presents results of research on the wetting ability of aqueous solutions of short-chain alcohols in relation to selected hydrophobic materials. Polyethylene and Teflon were used as standard hydrophobic smooth materials. Dried peat with granulation d < 0.5 mm was used as the porous hydrophobic material. Physical properties of alcohols and their solutions having a direct influence on the rate of saturation of capillary layers have been discussed. The wettability of smooth surfaces was characterized by the advancing and receding contact angles and wetting tension, defined as the product of the liquid surface tension and cosine of contact angle. The contact angles were determined by Wilhelmy’s method using the Krüss K-100 tensiometer. Wettability of peat was determined by measuring the mass rate of liquid imbibition by capillary forces. For comparison, analogous tests of wettability and capillary imbibition rates were carried out using sodium dodecyl sulfate solutions and solutions of typical wetting agent used in firefighting activities. The solutions of surfactants, in the range of concentrations used in extinguishing operations, showed much better wetting properties in relation to a smooth hydrophobic surface (polyethylene) than solutions of alcohols in the entire range of concentrations (up to 100%). The imbibition capacity of the hydrophobic peat layers of alcohol solutions with concentrations above 10% was higher than the solutions of surfactants.
Extrusion Process of Polypropylene Composites Reinforced Milled Carbon Fibre for Conductive Polymer Composite Application
Authors: Radzuan Nabilah Afiqah Mohd , Sulong Abu Bakar , Somalu Mahendra Rao
Published: December 2018

A polypropylene (PP) reinforced milled carbon fibre (MCF) was developed to produce high conductive polymer composites. Theoretically, by altering the filler orientation, the electrical conductivity and mechanical properties can be controlled. However, the orientation techniques which influence the MCF fibre are difficult to performed. Therefore, this study focused on controlling the filler orientation through the extrusion process. Hence, the extrusion temperature of 230°C and rotational speed of 50 rpm at 70 wt.% of MCF and 30 wt.% of PP were used. The electrical conductivity in perpendicular to the extrusion direction was higher at 2.0 S/cm as compared to 0.66 S/cm in the parallel direction. Besides, the extruded composite of rod and sheet were studied in which rod dies offers higher electrical conductivity of 3.0 S/cm and better mechanical properties of 1225 MPa than the sheet dies. Alteration in filler orientation aid in enhancing the electrical conductivity as minimum fillers breakage occurred due to the low shear rate of 2.2 s-1 which indirectly induces the filler to the desired orientation. Therefore, the extrusion process able to improve the electrical conductivity and mechanical properties of composite materials, as the filler oriented perpendicular to extrusion direction.
Patients’ Loyalty Improvement in Public Hospital
Authors: Dachyar M. , Farizal  , Minar Ika Prisila
Published: December 2018

The purpose of this research is to improve outpatient loyalty in using National Health Insurance in a public hospital. Structural Equation Modeling (SEM) method is used to analyze factors that influence patient loyalty. The discriminant analysis method is used to know the priority for improvement. An assessment of 5 experts was performed to obtain latent variables and indicators. The questionnaire was given to 400 patients. The SEM model is concluded, satisfaction and trust are two strong factors that affect the loyalty of patients.
Quality Improvement of Industrial Products Bungo Mayang to Customer Satisfaction with The Kano Model Approach
Authors: Muchtiar Yesmizarti , Mufti Dessi , Yosri Vil
Published: December 2018

The abundance of the home industry appeared in the Batusangkar requires home industry Bungo Mayang should retain the factors that affect the quality of the product so that it can continue to exist and remains sought after by the public. This research aims to identify the attribute customer needs to improve product quality ‘kue karambia’ Bungo Mayang and classifying the attributes customer needs based on model of Kano. The instrument used was a questionnaire functional and dysfunctional questionnaires grouped into attributes of the Kano must-be, one dimensional, attractive, indifferent, quesionable result, and reverse. From the results of the calculation model Kano note that attributes have the highest grade IE product quality is good (O = 66), the attractive packaging (O = 61), availability of product information (O = 56), and compliance rates (O = 43).
Understanding the Behavioral Intention to Use a University Web-Portal
Authors: Aditia Ezra , Tela I Nengah , Saleh Nursyam , Ilona Desi , Zaitul
Published: December 2018

Behavioral intention to use the information technology is a predictor of behavioral to use it. There are several studies investigating the effect of factors from Technology Acceptance Model (TAM) on attitude toward use and its effect on behavioral intention to use which based on Theory of Plan Behavior (TPB). However, there is a limited studies emphasizing on academic portal in a university. Therefore, this study investigates the effect of perceived ease of use (PEU) and perceived usefulness(PU) on attitude toward use (ATU) and Behavioral intention to use (BIU). Further, this study also aims to determine the relationship between attitude toward use (ATU) and behavioral intention to use (BIU). Using 123 registered students in four faculties, smart path least square (PLS) is applied to analysis the data. The findings show that PEU has a positive significant relationship with BIU and ATU. In addition, ATU also has a significant positive effect on BIU. However, PU do not have a significant relationship with BIU and ATU. This study has practical and theoretical implication and it discuss in detail in paper.
Determinants of web-user satisfaction: using technology acceptance model
Authors: Zaitul  , Ramadhani Fanny , Ilona Desi
Published: December 2018

This study investigates the determinant of web-user satisfaction. User satisfaction is successful measurement for IT implementation. Technology Acceptance Model and Theory of Plan Behaviour are used to underpin the relationship. Two variables are applied as determinants of web-user satisfaction: perceived usefulness and perceived ease of use. Students from four faculties are used as research object and questioner were distributed online by giving URL-Link through WhatsApp. 53 Students filled the questioners. Smart-PLS use to analyse data. The finding show that perceived ease of use has a positive relationship with user satisfaction. However, perceived usefulness does not have a significant relationship with user satisfaction. This study has a practical and theoretical implication. Practically, the finding can be used to formulate the future university website development. Theoretically, this study contributes to the Technology Acceptance Model and Theory of Plan Behaviour.
Enhancement of surface roughness for brittle material during rotary ultrasonic machining
Authors: Sharma Ankit , Babbar Atul , Jain Vivek , Gupta Dheeraj
Published: December 2018

Surface roughness is the key aspect which could increase the application of float glass by enhancing the machined hole quality. Glass is extensively used in microfluidic devices, bio-medical parts and biosensors. The core objective of the research study is to optimize the best parametric combination to achieve the least amount of surface roughness. The three major parameters which are used for designed experimental study are spindle speed, ultrasonic amplitude and feed rate. The least value of surface roughness is noticed at spindle speed (5000 rpm), vibration amplitude (20 μ m) and feed rate (6 mm/min) which be adopted for increasing its functional application. Consequently, after optimizing the parameters, least value of surface roughness at hole internal region is revealed as 1.09 μm.
The competitive effect of non-magnetic defect and films thickness on the ferromagnetic critical temperature in Ising thin-films
Authors: Jaroenjittichai Atchara Punya , Laosiritaworn Yongyut
Published: December 2018

In this work, Monte Carlo simulation was employed to investigate the competitive effect of non-magnetic defects and the thickness on the ferromagnetic behavior of Ising spins in a reduced geometry, i.e. thin-films. The magnetic properties were investigated as functions of temperature, defect concentration, and films’ thickness, especially in the ferromagnetic phase transition region. The finite size scaling was performed via the fourth order cumulant of the magnetization to extract the critical temperatures. From the results, the extracted critical temperatures agree well with previous theoretical investigation, where applicable. With increasing concentration of the nonmagnetic defects, the Ising phase-transition-point slightly shifts towards lower temperature, while the increase of films thickness enhances the critical temperature value. Being confirmed by the main-effect-plot analysis, the increase in thickness has much greater influences on the critical temperature than that of the defect concentration, which could be described in term of the average ferromagnetic interaction spin. As the role of the defect is negligence in the range of considered defect concentration (up to ten percent), it therefore suggests that the preparation of ferromagnetic films can be done in normal operating condition where defects usually occur. It may be not economically worth to aim for the perfectly smooth films when the associated application operates at temperatures away from the critical point.
Innovative Building Material for the House Construction for Solar Decathlon Middle East 2018 Competition
Authors: Cazacova Liudmila , Bait Farhan Marwan
Published: December 2018

This experimental report describes the invention of a new type of block for the construction of a sustainable house for the Solar Decathlon Middle East 2018 Competition by the team SoLLite-Salalah from Dhofar University, Sultanate of Oman. The aim of the experiment was to create a material for exterior walls’ construction that is environmentally friendly, light, easy to transport and assemble, resistant to heat transfer, and also with low manufacturing cost. The paper describes the project SoLLite-Salalah, the experiment itself and provides the results of the tests, which show that the sample block made by the team fulfils the requirements and can be used for the construction of the exterior walls of the house. This report also demonstrates that Solar Decathlon Competitions stimulate research and innovation and promote the idea of efficient housing by educating and training students.
Effect of floating axial holder on oscillating cold forging of spline shaft
Authors: Ben N Y , Zhang Q , Lee M G
Published: December 2018

Oscillating technique is applied into the axial forging process of spline shaft to decrease the forming load and improve the quality of products. A floating axial holder with dwell force is designed to control the material flow. The influences of the floating axial holder have been analysed by finite element (FE) simulation and then verified by experiments. A FE model that considers material property change, elastic recovery and elastoplastic friction was built. The constitutive material model, which is mainly composed of variable elastic modulus and rate-dependent hardening, was used to simulate changes in material properties. Results showed that material flow was improved by decreasing dwell force. Tooth shape can be controlled by changing the dwell force of floating axial holder. The nonlinear function between addendum circle diameter and dwell force has been found. Hence, an optimal value of dwell force was determined considering the forming force, forming defects and tooth shape. Based on the simulating results, the optimal and irrational parameters of dwell force and frequency have been compared in the experiments. The typical defects of flash and accumulation can be eliminated by using the floating axial holder with optimal parameters.
Empirical Modeling of Average Cutting Speed during WEDM of Hastelloy C22
Authors: Singh Bhupinder , Misra Joy Prakash
Published: December 2018

Cutting speed (CS) is a key performance measure to achieve optimal utilization of the WEDM process. However, input process parameters of WEDM and combination of wire and workpiece material greatly hamper CS and hence productivity and machining efficiency. Therefore, it is essential to pick the right combination of parameters and wire and workpiece material to obtain better CS. In this paper, four process parameters: Pulse-on time, Pulse-off time, Spark-gap voltage, and Peak current were chosen to develop an empirical model for CS during WEDM of Hastelloy C22 to provide a guideline to the potential users of the technique. This paper describes the response surface methodology (RSM) based mathematical modeling for average cutting speed. Furthermore, analysis of variance (ANOVA) was applied to find out significant process parameters and it was depicted that pulse on time and peak current were the major parameters affecting CS.
High-precision finishing hard steel surfaces using hydrostatic burnishing tool
Authors: Swirad S
Published: December 2018

The objective of this research aims to improve surface roughness of the hardened 145Cr6 (DIN) steel using the hydrostatic burnishing tool. The ball burnishing process with hydrostatic tools is very economical finishing process for various types of machine parts. This process reduces the height of surface unevenness, introduces compressive stresses at high depth (approx. 1 mm) and increase the hardness of the surface layer. The flat surface optimal ball burnishing parameters have been determined after conducting the Taguchi L9 matrix experiment. The input parameters are speed, burnishing force and burnishing width. It also showed a positive effect of hydrostatics burnishing on roughness and geometric structure of the surface. In most cases, the result is anisotropic surface, reduced roughness, reduced amplitude values of parameters such as: Sa, Sz.
Study on the performance of journal bearings in different lubricants by CFD and FSI method with thermal effect and cavitation
Authors: Li Hulin , Wang Yanzhen , Zhong Ning , Chen Yonghong , Yin Zhongwei
Published: December 2018

This paper used a new transient computational fluid dynamics and fluid–structure interaction method to investigate the journal bearing performance with the effect of thermal and cavitation, to reveal the performance of journal bearing in different lubricants and to provide substitution references for bearings in different lubricants. Considering thermal effect, elastic deformation and cavitation, a detailed discussion was conducted to show the performance of plain journal bearings lubricated by water, seawater, and lubricating oil by computational fluid dynamics (CFD) and fluid structure interaction (FSI) method. And the results in this work are compared with the published results. The variation of dimensionless load carrying capacity, maximum film pressure and temperature with eccentricity ratio are presented, which can provide reference for the design of bearings. Furthermore, a diagram is presented for journal bearings with different diameter, length-diameter ratio and lubricants, which can be used as a reference for the equivalent substitutions of bearings. The present research provides references as to the design of bearings and the substitutions of bearings by different lubricants.
Operational Flammability Limits of Commercial Fuels – A Review
Authors: Al Mughanam Tawfiq
Published: December 2018

This manuscript considers the operational flammability limits of commercial fuels used in the automotive and in the aviation industry. Commonly employed fuels are considered in this study. Understanding the flammability limits is an important aspect while choosing right fuel for a given application. An explosion of stored fuel or combustion system can be catastrophic and can create a serious impact to the society. Therefore, researchers while developing fuels and combustion systems must give considerable attention. This manuscript reviews the effect of vapour pressure and temperature on flammability of fuels and reviews the auto ignition and flash point temperature of fuels commonly seen in the automotive and in the aviation industry.
Vésicules extracellulaires, biomarqueurs et bioeffecteurs du syndrome métabolique
Authors: Le Lay Soazig , Martinez M. Carmen , Andriantsitohaina Ramaroson
Published: December 2018

Les vésicules extracellulaires (VE) suscitent un intérêt croissant lié à leur capacité à transférer du contenu biologique entre cellules. Les VE, émises dans l’espace extracellulaire, circulent via les différents fluides de l’organisme et modulent localement ou à distance les réponses des cellules avec lesquelles elles ont interagi. Des données cliniques et expérimentales étayent leur rôle dans les maladies liées au syndrome métabolique. Les VE bousculent la vision traditionnelle de la communication intercellulaire et représentent ainsi un mode de communication alternatif et versatile, qui ouvre la porte à de nouveaux concepts et opportunités tant biologiques que thérapeutiques.
Cinquante nuances de pluripotence
Authors: Afanassieff Marielle , Aksoy Irène , Beaujean Nathalie , Bourillot Pierre-Yves , Savatier Pierre
Published: December 2018

Depuis la dérivation des premières lignées de cellules souches embryonnaires pluripotentes chez la souris au début des années 1980, une pléthore de lignées a été obtenue chez diverses espèces de mammifères, dont les rongeurs, les lagomorphes et les primates. Ces lignées se distinguent par leurs caractéristiques moléculaires et fonctionnelles et correspondent aux différents états de pluripotence observés chez l’embryon, entre les stades blastocyste et gastrula. Ces lignées se répartissent le long d’un gradient, ou continuum de pluripotence, dont les deux extrémités sont symbolisées par les états appelésnaïfetamorcé. Les cellules souches pluripotentes humaines sont dans un état de pluripotence amorcé (au bas du gradient), une position qui est sans doute la cause de leur instabilité naturelle. Les recherches récentes visent à obtenir des cellules souches pluripotentes humaines à l’état naïf (en haut du gradient). L’importance de ces recherches dans la perspective d’applications médicales est discutée dans cette revue.
De l’irruption de la mécanique dans la chimie du vivant
Authors: Mège René Marc , Ladoux Benoit
Published: December 2018

Les contraintes mécaniques sont enfin reconnues comme un régulateur clé des processus biologiques, des molécules aux organismes, tout au long du développement embryonnaire, de la régénération tissulaire et dans des situations de régulations physiologiques et de dérèglements pathologiques. L’étude de l’influence de ces contraintes physiques sur le vivant, en particulier sur les cellules et les organismes du règne animal, font l’objet depuis une décennie d’importants travaux menés aux confins de la biologie, de la physique et de la mécanique, constituant une nouvelle discipline, la mécanobiologie. Nous décrivons ici brièvement les avancées remarquables dans la compréhension de la manière dont les cellules et les tissus à la fois génèrent et perçoivent les contraintes mécaniques et comment ces contraintes dictent, en retour, les changements de forme, les migrations et enfin la différenciation des cellules au cours de la morphogenèse, à la suite de lésions, lors de la réparation et de l’adaptation des tissus à leur environnement.
An Exploratory Study of the Impact of the Summer English Teaching Service-learning Program in a Remote Area of Yunnan Province, China
Authors: Ma Carol Hok Ka , Cheung Fabia Shuk Ling
Published: December 2018

This exploratory study examines a three-year Summer English Teaching Service-Learning Program (SETSLP) in a high school in Yunnan, China. Students from Lingnan University acted as tutors to teach English to around 300 Chinese students of which 181 participants finished and returned the questionnaires over the three years of SETSLP through a Communicative Language Teaching (CLT) approach from 2009 to 2011. Results showed that CLT significantly (i) increased the students’ self-perceived English abilities in the areas of listening (t = 2.62, p < .05 in 2009; t = 4.60, p < .01 in 2011), comprehension (t = 2.33, p < .05 in 2009; t = 5.16, p < .01 in 2010; t = 7.11, p < .01 in 2011), and oral communication (t = 2.22, p < .05 in 2009; t = 6.39, p < .01 in 2010; t = 7.85, p < .01 in 2011); (ii) increased the students’ confidence in speaking English as most students throughout the three years chose oral ability as their greatest achievement in the program; and (iii) increased the students’ interest and motivation in learning English. Students also revealed that SETSLP increased their interest in English and students were more motivated to learn English (Mean = 8.44, SD = 1.51). Besides, students mentioned that the tutors who participated in the service-learning program, played a crucial role to encourage and motivate them to learn English. This also teaches the students the importance of doing service-learning in their daily life.
Diversity, Unity, and Global Citizenship Education: A Case Study in Community Outreach Program in Indonesia
Authors: Anggono Juliana , Lim Resmana , Limbong Frans , Palit Herry Christian , Wartono Poedi Soenarjo
Published: December 2018

Community Outreach Program is an established international service-learning program which has been around for 22 yr. The program offers an inter-discipline activity set in an international atmosphere to connect the academic theories with the actual social life and problems in the less developed rural community in East Java Province, Indonesia. There have been students from 16 university partners from 10 different countries ever participating in the program. Studies from the observations and opinions by the university partners claimed that COP has had an impactful outcomes in students‟ learning in the areas of diversity awareness, citizenship, and values development. The first study in 2009 on students‟ expectations in participating in COP reported that the students were aware that joining COP would expose them in diversity through working along with international friends and the community in the village. In this current study, 90 reflection books of COP 2015 Asian participants from Japan, Hong Kong, South Korea, and Indonesia were further studied to test and evaluate how COP as a service-learning program has provided an education setting to educate caring and responsible citizens, who were open to other cultures, and respectful of differences. Students' responses affirmed the positive effects of COP on the acceptance of diversity and sense of civic responsibility.
Enhancing Civic Engagement Through International Service-learning to Impact Village Community
Authors: Halim Siana , Anggono Juliana
Published: December 2018

Every year during semester break in July to August, Petra Christian University holds an international service-learning which is popularly known as Community Outreach Program (COP). This program has been conducted for 20 yr since 1996 in which more than 15 university partners from 10 different countries have participated in COP. In this research the impact of COP on the community served through a survey done on 140 residents of twelve villages in Mojokerto regency, East Java province in Indonesia is studied. Cultural exchange between the villagers and the students was also measured, particularly with the overseas participants. Additionally, the economic impact and the villagers’ wish for a better service that the coming COP can provide, is also investigated. The results indicate that the villagers were satisfied with the programs, either physical or non-physical programs implemented in the village during COP. The presence of the overseas students in their villages made them learn cultural, language, and religion diversities. Even though, languages were the barrier for them to communicate with the foreign students, but they treated those students as if they were their own children. The villagers hope that this program will be continued.
Objective evaluation of blood flow in the small-intestinal villous: quantification of findings from dynamic endoscopy with concomitant narrow-band imaging
Authors: Takeyama Tomoaki , Hirooka Yoshiki , Kawashima Hiroki , Ohno Eizaburo , Ishikawa Takuya , Yamamura Takeshi , Furukawa Kazuhiro , Funasaka Kohei , Nakamura Masanao , Miyahara Ryoji , ishigami Masatoshi , Goto Hidemi
Published: December 2018

Background and aims We have previously shown that the increase in blood flow volume in jejunum villi after spraying of 10 % dextrose solution correlates with pancreatic exocrine function (PEF). The aim of this study was to establish an objective method to evaluate the amount of jejunum villous blood flow using a novel image analysis system.

Patients and methods The subjects were 26 patients who underwent upper gastrointestinal endoscopy with a newly developed small intestine endoscope (SIF-Y0007, Olympus, Tokyo, Japan). By defining the ratio of capillary occupancy in each villus at levels from 1 to 5, villous blood flow was evaluated subjectively on the villous blood flow scale (VBFS). Objective evaluation was performed based on luminance analysis. The morphological opening process was used to make images with leveled brightness. A histogram was prepared from the luminance information and the standard deviation was determined and defined as SDOV (Standard Deviation calculated from a histogram made by luminance analysis Of Villi). PEF was evaluated by measuring the BT-PABA (N-benzoyl-L-tyrosyl-p-aminobenzoic acid) excretion rate.

Results There was a significant positive correlation between VBFS and SDOV (P < 0.0001, ρ = 0.5882). SDOV was also positively correlated with PEF (P = 0.0004, ρ = 0.6421).

Conclusions SDOV is a new objective index for evaluation of blood flow volume in jejunum villi. SDOV may be useful in clinical practice to estimate PEF and for clarification of the mechanisms underlying the functional correlation between the pancreas and small intestine.
Singular solutions in nonlinear parabolic equations with anisotropic nonstandard growth conditions
Authors: Liu Bingchen , Dong Mengzhen , Li Fengjie
Published: December 2018

In this paper, we study extinction and blow-up properties of weak solutions for the doubly nonlinear parabolic problem involving p(x, t)-Laplacian operator, subject to homogeneous Dirichlet boundary conditions. We first prove the existence and uniqueness of weak solutions in some anisotropic Orlicz-Sobolev spaces and also establish suitable regularity of weak solutions with respect to the introduced control functional. Second, we use the energy estimate and the comparison principle of the ordinary differential equation to study the extinction or non-extinction of solutions. Third, we combine some new energy functions with the embedding inequalities to show blow-up criteria of solutions. Moreover, the singular rates of weak solutions are determined. It is interesting that blow-up or extinction phenomena depend sensitively on the sign of the precise relationship among the different anisotropic variable exponents, which discovers a key clue to the different effects of diffusion and reaction of the equations on the singularities of weak solutions.
Measuring the orientation of the flexural vibrations of a cantilevered microwire with a micro-lens fiber-optic interferometer
Authors: Fu Chenghua , Zhu Wanli , Deng Wen , Xu Feng , Wang Ning , Zou Lvkuan , Xue Fei
Published: December 2018

Optical interferometers are powerful tools for studying the flexural vibrations of nano- and micro-mechanical resonators. When a cantilevered microwire vibrates along a direction away from the optical axis, the interference signal may not be optimal for detecting its vibrations. In this work, we identify the optimal locations for detecting the vibrations of a cantilevered microwire using a micro-lens fiber-optic interferometer. We take both the interference effect and the scattering effect of the microwire into account. Using a home-built interferometer, we verify the analysis by measuring a cantilevered microwire driven in various directions with respect to the optical axis. Our results show that the optimal detecting location strongly depends on the orientation of the vibrations. Based on this observation, we inferred the orientations of the flexural vibrational modes of two cantilevered microwires. Our results may be useful in studying the flexural vibration modes of cantilevered microwires and their applications in detecting vectorial forces.
Hybrid global maximum power point tracking algorithm under partial shading condition
Authors: Yu Songsen , Zhang Xing , Yin Lulin
Published: December 2018

This paper presents a hybrid global maximum power point tracking (MPPT) algorithm under partial shading conditions, which consists of five methods, including the global scanning method, the filtering method, the binary searching method, the three-point method, and the anti-restarting method. By making full use of the advantages of these methods, the proposed algorithm is able to improve tracking speed and efficiency, decrease oscillation, and avoid restarting. Among which, the global scanning method is used to find all the local intervals, the filtering method is used to reduce the search area, the binary searching method is used to reduce the search time, the three-point method is used to track the global maximum power point dynamically, and the anti-restarting method is used to prevent restarting the algorithm. To verify the proposed algorithm, experiments have been carried out in a standard environment, dynamic solar irradiation, and dynamic temperature, respectively. The performance of the proposed algorithm is verified by comparing it with a perturb and observe (P&O) based global scanning MPPT method and a modified P&O with checking MPPT method using computer simulations.
Multilevel resistive and magnetization switching in Cu/CoFe2O4/Pt device: Coexistence of ionic and metallic conducting filaments
Authors: Munjal Sandeep , Khare Neeraj
Published: December 2018

Non-volatile, multilevel bipolar Resistive Switching (RS) along with multilevel magnetization switching, in a cobalt ferrite (CFO) thin film using a simple Cu/CFO/Pt sandwich structure, has been demonstrated. Besides the low resistance state (LRS) and the high resistance state (HRS), the device exhibits two intermediate resistance states (IRSs), which are stable with time and reproducible in RS cycles. The endurance characteristics of the present RS device (>500 switching cycles) show no noticeable degradation and the ultimate resistance ratio always remains >104, which ensures reproducibility, reversibility, and controllability of the RS features of the present device. The HRS of the device shows a semiconducting conduction mechanism, whereas the LRS and both the IRSs were found to be Ohmic in nature. Simultaneous magnetization and resistive switching confirmed the multifunctional behavior of the device and suggested the presence of a valence change mechanism of resistive switching. The magnetization vs. magnetic field studies and temperature dependent resistance studies revealed that the electrochemical metallization also plays an important role during the switching process, which enhances the resistance ratio by providing an additional metallic filament of Cu atoms along with the ionic conducting filament of oxygen vacancies. The voltage controlled multilevel magnetization and resistive switching with a large memory window (resistance ratio >104) make the present device a potential candidate for paving the path for future multifunctional and multilevel memory devices with the capability of high density data storage.
The ideal commensurate value of Sc and the superconducting phase under high pressure
Authors: Tsuppayakorn-aek Prutthipong , Luo Wei , Pungtrakoon Wirunti , Chuenkingkeaw Kittana , Kaewmaraya Thanayut , Ahuja Rajeev , Bovornratanaraks Thiti
Published: December 2018

The host–guest structure of scandium is described as being built of two penetrating substructures with the incommensurate periods of the channels along the c axis. We present the ideal commensurate value of 4/3 in Sc-II using ab initio calculations. We reveal that the 3cH and 4cG structures do interpenetrate and combine to the commensurate value of 4/3 of Sc-II at a pressure of 70 GPa. Ab initio molecular dynamics confirms the stability of the commensurate value 4/3 of the host–guest structure at 300 K and 72 GPa. The pressure-induced structural phase transitions in scandium under high pressure up to 200 GPa are investigated. We use ab initio random structure searching to predict the crystal structure of Sc-III: it is the tetragonal structure with space group P41212. Our calculations show that superconductivity arises in the P41212 structure. This high pressure structure is not only a superconducting phase but also has been reported for the first time in this group of elements.
Integrated photocapacitors based on dye-sensitized TiO2/FTO as photoanode and MnO2 coated micro-array CNTs as supercapacitor counter electrode with TEABF4 electrolyte
Authors: Yilmaz Mesut , Hsu Shao-Hua , Raina Supil , Howell Mick , Kang Weng P.
Published: December 2018

Harvesting solar energy using dye-sensitized solar cells (DSSCs) has been a promising option. Successful integration of a DSSC electrode with an energy storage electrode represents the next challenge for the researchers. In this paper, the fabrication and characterization of an integrated dye-sensitized photoanode and a supercapacitor cathode or a photocapacitor has been presented. This novel device employs N-719 dye-sensitized titanium dioxide on fluorine-doped tin oxide glass substrate as the photoanode. The supercapacitive counter electrode comprises MnO2 coated, vertically aligned, micro-array patterned carbon nanotubes (MA-CNTs). The CNTs were grown on n++ silicon (Si) substrates in a hot filament chemical vapor deposition system followed by in-situ electrochemical deposition of MnO2. Tetraethyl ammonium tetrafluoroborate electrolyte was used to investigate the photovoltaic and energy storage performances of the photocapacitors under 1-sun illumination and constant-current discharge tests. A high discharge capacitance of 13 mF/cm2 at 0.932 V was achieved by coating MnO2 onto the high surface area of MA-CNTs due to the pseudocapacitive behavior of MnO2, which led to a nearly 3-fold increase in the short circuit current density to 0.749 mA/cm2 and more than a 2-fold enhancement in the open circuit voltage to 0.46 V, as compared to the baseline CNT counter electrode. The corresponding increase in the fill factor and efficiency was also observed. Overall, we have demonstrated the viability of a compact, easy to fabricate, integrated photocapacitor with promising energy generation/storage performance.
Fully integrated optical isolators for space division multiplexed (SDM) transmission
Authors: Jung Yongmin , Wood Andrew , Jain Saurabh , Sasaki Yusuke , Alam Shaif-Ul , Richardson David J.
Published: December 2018

A micro-optic collimator assembly represents an important platform for the realization of many commonly used fiber optic components and devices including optical isolators, circulators, gain flattening filters, and so on. In this paper, we investigate the incorporation of space division multiplexing (SDM) fibers (particularly, few mode fibers and multicore fibers) in a micro-optic collimator assembly and develop a technology base to provide fully integrated SDM components. A few exemplary SDM fiber isolators (e.g., 3 or 6-moded fiber isolator and a 32-core multicore fiber isolator) are successfully fabricated with low insertion loss and low mode (or core) dependent losses. Improved sharing of the functional optical element and significant device integration is efficiently achieved in these devices as will be required to ultimately realize the anticipated cost reduction benefits of SDM technology.
Z-scanning laser photoreflectance as a tool for characterization of electronic transport properties
Authors: Chism Will
Published: December 2018

The physical principles motivating the Z-scanning laser photoreflectance technique are discussed. The technique is shown to provide a powerful non-contact means to unambiguously characterize electronic transport properties in semiconductors. The technique does not require modeling of charge transport in the sample or a detailed theoretical model for the sample physics. Rather, the measurement protocol follows directly from the simple relation describing the radial diffusion of carriers injected by a laser source. The use of a probe laser beam permits an analytic parametrization for the Z dependence of the photoreflectance signal which depends solely on the focal parameters and the carrier diffusion length. This allows electronic transport properties to be determined with high precision using a nonlinear least squares fit procedure. The practical use of the technique is illustrated by the characterization of carrier transport properties in semiconducting p-n junctions.
Activation thresholds in epidemic spreading with motile infectious agents on scale-free networks
Authors: Silva Diogo H. , Ferreira Silvio C.
Published: December 2018

We investigate a fermionic susceptible-infected-susceptible model with the mobility of infected individuals on uncorrelated scale-free networks with power-law degree distributions P(k)∼k−γ of exponents 2<γ<3. Two diffusive processes with diffusion rate D of an infected vertex are considered. In the standard diffusion, one of the nearest-neighbors is chosen with equal chance, while in the biased diffusion, this choice happens with probability proportional to the neighbor’s degree. A non-monotonic dependence of the epidemic threshold on D with an optimum diffusion rate D∗, for which the epidemic spreading is more efficient, is found for standard diffusion while monotonic decays are observed in the biased case. The epidemic thresholds go to zero as the network size is increased and the form that this happens depends on the diffusion rule and the degree exponent. We analytically investigated the dynamics using quenched and heterogeneous mean-field theories. The former presents, in general, a better performance for standard and the latter for biased diffusion models, indicating different activation mechanisms of the epidemic phases that are rationalized in terms of hubs or max k-core subgraphs.
Epitaxial lateral overgrowth of α-Ga2O3 by halide vapor phase epitaxy
Authors: Oshima Y. , Kawara K. , Shinohe T. , Hitora T. , Kasu M. , Fujita S.
Published: December 2018

We demonstrate the epitaxial lateral overgrowth of α-Ga2O3 by halide vapor phase epitaxy. We prepared patterned SiO2 masks on a (0001) α-Ga2O3/sapphire template, and then α-Ga2O3 islands were regrown selectively on the mask windows. The islands grew vertically and laterally to coalesce with each other. Facet control of the α-Ga2O3 islands was achieved by controlling the growth temperature, and inclined facets developed by decreasing the temperature. Transmission electron microscopy revealed that the crystal quality of the regrown α-Ga2O3 was improved owing to both the blocking of dislocations by the mask and the dislocation bending by the inclined facets.
The strain hardening of micro-sized face-centered-cubic single crystal metals: A crystal plasticity study
Authors: Guo Huili , Li Chenlin , Zhang Xu , Shang Fulin
Published: December 2018

Recent experimental and theoretical studies indicate the “external geometry” and “internal structure” are the controlling factors to characterize the size-dependent plastic flow for micro-sized single crystal metals. i.e., increasing yield strength with decreasing sample size. This paper aims to investigate the strain hardening behavior for micro-sized face-centered-cubic (FCC) metals by employing crystal plasticity approach. The size-dependent dislocation density evolution law incorporates the dimensional parameters of internal structure and external geometry in order to consider the dislocation surface annihilation and dislocation source controlled plastic mechanisms. The current shear yield strength for micro-sized FCC metals is formulated by introducing the dislocation source length in classical anisotropic hardening model of Franciosi type. Combined with the above two aspects, crystal plasticity finite element method is developed to examine the strain hardening behavior of single crystal micro-sized metals during uniaxial compression. The validity of the new theoretical formulation and modeling approach is checked by comparing the simulation results with the experimental results available in literatures. The simulation results indicate that the micro-sized FCC metals have significant size effect. Further studies are performed to evaluate the influences of the initial dislocation density and the number of dislocation sources on strain hardening behavior of micro-sized FCC metals.
Compact acoustic double negative metamaterial based on coexisting local resonances
Authors: Cai Xiaobing , Xiao Junfeng , Zhang Hongkuan , Zhang Yue , Hu Gengkai , Yang Jun
Published: December 2018

Acoustic metamaterials generally exploit resonances to assume negative properties. While many types of resonances can be used for achieving a negative bulk modulus, the number of types of resonances for generating a negative mass density is limited. In this work, a double negative airborne acoustic metamaterial is proposed, whose negative density is achieved from Fabry-Pérot resonance. More specifically, each unit cell of the metamaterial comprises only a single element, allowing coexistence of local Helmholtz resonance and Fabry-Pérot resonance to simultaneously generate a negative modulus and negative density. The metamaterial exhibits a reversed phase velocity and negative refraction, even if the constitutional elements are randomly distributed. This is a pioneering work that an airborne acoustic double negative metamaterial derives negative density from Fabry-Pérot resonance and maintains negative refraction with its constitutional elements randomly distributed.
A study of strain-induced indirect-direct bandgap transition for silicon nanowire applications
Authors: Li Song , Chou Jyh-Pin , Zhang Hongti , Lu Yang , Hu Alice
Published: December 2018

Recently, ultralarge (>10%) strain with fully reversible elastic deformation has been experimentally achieved in silicon nanowires [H. Zhang et al., Sci. Adv. 2, e1501382 (2016)]. With this breakthrough, here in this work, based on the first principles calculation, the structural and electric properties of silicon under ultralarge strain are comparatively investigated. Unlike previous theoretical/simulation investigations on silicon nanowires with only a few nanometers, bulk silicon models are employed here to provide more realistic and comparable results to our experimentally tested samples (∼100 nm diameter). Strong anisotropic effects are induced by loading strain along all different orientations. Simultaneously, the band structures evolution demonstrates electronic anisotropy with the loading strain on three orientations. Silicon keeps an indirect bandgap under increased strain along the ⟨100⟩ orientation while transforming to a direct bandgap with strain along ⟨110⟩ and ⟨111⟩ orientations. Furthermore, ultralarge strain on these two orientations would diminish the bandgap and result into metallization. These results provide insights into understanding “elastic strain engineering” of silicon nanowire applications and demonstrate the possibility of tuning the electronic and optical properties through pure mechanical straining of functional materials.
Atomic scale depletion region at one dimensional MoSe2-WSe2 heterointerface
Authors: Chu Yu-Hsun , Wang Li-Hong , Lee Shin-Ye , Chen Hou-Ju , Yang Po-Ya , Butler Christopher J. , Lu Li-Syuan , Yeh Han , Chang Wen-Hao , Lin Minn-Tsong
Published: December 2018

Lateral heterojunctions based on two dimensional (2D) transition metal dichalcogenides (TMDCs) potentially realize monolayer devices exploiting 2D electronic structures and the functions introduced by the presence of 1D heterointerfaces. Electronic structures of a lateral MoSe2-WSe2 junction have been unveiled using scanning tunneling microscopy and spectroscopy. A smooth and narrow depletion region exists despite a defect-rich heterointerface deviating from the preferred zigzag orientations of the TMDC lattice. From the characteristics of the depletion region, a high carrier concentration and high internal electric fields are inferred, offering to benefit designs of lateral TMDC devices.
Correlation between epitaxial strain and magnetic properties in La0.7Sr0.3CoO3/La0.7Sr0.3MnO3 bilayers
Authors: Byers J. Paige , Li Binzhi , Chopdekar Rajesh V. , Ditto Jeffrey , Johnson David C. , Takamura Yayoi , Browning Nigel D.
Published: December 2018

Magnetic properties arising at interfaces of perovskite oxides such as La0.7Sr0.3CoO3 (LSCO) and La0.7Sr0.3MnO3 (LSMO) depend sensitively on the fine details of their structural properties. In this work, we use high-resolution transmission electron microscopy and spectroscopy to examine the structural and electronic phenomena at the interfaces in two LSCO/LSMO bilayers with reversed growth order. Two different strain mechanisms are at work in these films: compressive or tensile epitaxial strain, and distortion of the octahedral tilt pattern to maintain a network of corner-sharing octahedra. While the epitaxial strain is constant regardless of the growth order, the modification of the octahedral tilt pattern depends on whether the film is grown directly on the substrate or as the second sublayer. As a consequence, exchange spring behavior is observed only when the LSCO sublayer is grown first. The different mechanisms of strain accommodation within the oxygen octahedra network in each material proved to be of critical importance in determining the interfacial structure and thus magnetic and electronic properties of the bilayers.