bluuebunny/crossref_metadata_2025 huggingface dataset:
Молекулярные состояния композитных фермионов в самоорганизованных квантовых точках InP/GaInP в нулевом внешнем магнитном поле
Authors: Минтаиров А.М.
Published: January 2020

Abstract The size and positions of regions of line localization and the magnetic-field (0–10 T) dependence of the low-temperature (10 K) photoluminescence spectra of single InP/GaInP quantum dots with a number of electrons of N = 5–7 and a Wigner–Seitz radius of ~2.5 are determined using a near-field scanning optical microscope. The formation of composite fermion molecules with a size coinciding with that of localization regions and bond lengths of ~30 and 50 nm, respectively, at a Landau-level filling factor from 1/2 to 2/7 in zero magnetic field is established. At N = 6, the pairing and rearrangement of composite fermions under photoexcitation are found, which offers opportunities for the use of InP/GaInP quantum dots to create a magnetic-field-free topological quantum gate.
Модель влияния смещения затвора при ионизирующем облучении МОП-структур
Authors: Александров О.В. , Мокрушина С.А.
Published: January 2020

The new quantitative model of influence of gate bias on the threshold shift of MOS-structures at the ionizing radiation which is based on the accounting of holes trapping in a thin border layer of gate dielectric on interface with a silicon substrate is developed. The model allows to describe the smooth growth of threshold shift with gate bias – approximately linear from a dose for a surface component and nonlinear for a volume component. The threshold shift at a negative gate bias is modelled on the basis of the accounting of holes generation at ionizing radiation in the border layer.
Длинноволновые светодиоды в окне прозрачности атмосферы 4.6-5.3 мкм
Authors: Романов В.В. , Иванов Э.В. , Пивоварова А.А. , Моисеев К.Д. , Яковлев Ю.П.
Published: January 2020

Abstract The design and technology for the fabrication of an asymmetric stepped InAs/InAs_1 –_ y Sb_ y /InAsSbP heterostructure with an ultimate InSb content (up to y = 0.17) in the narrow-gap active region by vapor-phase epitaxy from metal-organic compounds are developed. The electroluminescence characteristics of long-wavelength LEDs based on the proposed heterostructure, which emits in the spectral range of 4.6–5.3 μm, are studied. A linear decrease in the quantum efficiency of the electroluminescence with increasing InSb content in the active layer of the LEDs obtained is revealed. The advantage of using the asymmetric heterostructure for fabricating LEDs with a working wavelength of more than 4.5 μm is shown.
Диэлектрическая спектроскопия и особенности механизма фазового перехода полупроводник-металл в пленках VO-=SUB=-2-=/SUB=-
Authors: Ильинский А.В. , Кастро Р.А. , Пашкевич М.Э. , Шадрин Е.Б.
Published: January 2020

Abstract In the range of 0.1–10^6 Hz, the temperature-induced transformation of the frequency dependences of the dielectric-loss tangent tanδ( f ) as well as the Cole–Cole diagrams for undoped vanadium-dioxide films are investigated. The measurements are carried out in the temperature range T = 273–373 K. It is shown that the shape of the Cole–Cole diagrams for all films depends slightly on the temperature in the specified interval, while the frequencies f _0 corresponding to the peaks of the function tanδ( f ) increase with temperature. The thermal-hysteresis loops of the frequency positions f _0( T ) of the peaks are measured. When interpreting the data of dielectric spectroscopy, a complex equivalent electrical circuit of the sample is used; it makes it possible to detect the presence of two types of grains with different electrical properties in undoped VO_2 films. The presence of two types of grains determines the features of the semiconductor–metal phase-transition mechanism in VO_2 films.
Влияние температуры на морфологию планарных нанопроволок GaAs (моделирование)
Authors: Спирина А.А. , Шварц Н.Л.
Published: January 2020

Using a kinetic lattice Monte Carlo model, the self-catalyzed growth of planar GaAs nanowires was analyzed. The nanowire growth via the vapor-liquid-crystal mechanism was considered. The effect of temperature and the catalyst droplet location on the morphology and growth direction of planar GaAs nanowires was studied. For GaAs(111)A and GaAs(111)B substrates, a temperature range corresponding to stable growth of planar GaAs nanowires was revealed. The special asymmetric arrangement of droplets allows the one-directional nanowire growth.
Точно решаемая модель графеновой наноленты с зигзагообразными краями
Authors: Давыдов С.Ю. , Зубов А.В.
Published: January 2020

Abstract Exact analytical expressions for the local densities of states and the occupation numbers of atoms at the zigzag edge of a graphene nanoribbon are derived in the context of a simple structural model. As an example of application of the results, the problem of a Koster–Slater defect is considered.
Отрицательная дифференциальная проводимость структур на основе оксида лантана
Authors: Игитян А. , Агамалян Н. , Овсепян Р. , Петросян С. , Бадалян Г. , Гамбарян И. , Папикян А. , Кафадарян Е.
Published: January 2020

Using e-beam evaporation technique, transparent surface-hydrated lanthanum oxide (OH-La2O3) films with a thickness of 40, 140, and 545 nm were obtained. The electrical and optical characteristics of Al/OH-La2O3/p-Si structures were studied, where aluminum and a silicon substrate with p-type conductivity were used as the upper and lower electrodes, respectively.
Negative differential conductivity region in the conductivity–voltage characteristics for the forward bias voltage was found; a possible mechanism of negative differential conductivity is explained by proton transport in hydrogen bonded chains of water molecules at the OH-La2O3 film surface.
Эволюция дефектной структуры при испытаниях в режиме ползучести ультрамелкозернистых металлов и сплавов, полученных методами интенсивной пластической деформации
Authors: Бетехтин В.И. , Кадомцев А.Г. , Нарыкова М.В.
Published: January 2020

Using small-angle X-ray scattering, electron microscopy, and density measurements, structural factors have been identified that lead to a decrease in the mechanical stability of ultrafine-grained (UFG) metals and alloys when tested in creep mode at elevated temperatures. It has been established that one of the important factors is nanopores formed during intense plastic deformation. The development of these nanopores in grain boundaries formed during creep is realized by the diffusion mechanism and leads to destruction. The role of dispersed inclusions and high-angle grain boundaries for the strength of UFG metals and alloys under their “short-term” and long-term loading is considered.
Механизм открытия щели в точке Дирака в электронном спектре Gd-допированного топологического изолятора
Authors: Шикин А.М. , Естюнин Д.А. , Королева А.В. , Глазкова Д.А. , Макарова Т.П. , Фильнов С.О.
Published: January 2020

The electronic structure of magnetically-doped TI with stoichiometry Bi1.09Gd0.06Sb0.85Te3
in the region of the Dirac point has been studied in detail by angle-resolved photoelectron
spectroscopy (ARPES) at various temperatures (above and below the Néel temperature, 1-35 K)
and different polarizations of synchrotron radiation. It has shown that the energy gap in
photoemission spectra opens at the Dirac point and remains open above the temperature of the
long-range magnetic ordering, Tn. Measurements of magnetic properties by the superconducting
magnetometry method (SQUID) have shown antiferromagnetic ordering with a transition
temperature to the paramagnetic phase equal to 8.3 K. Study of the temperature dependence of
the Dirac cone state intensity at the Г point by ARPES has confirmed the magnetic transition
and has shown a possibility of its indication directly from photoemission spectra. A more
detailed analysis of the splitting between the upper and lower Dirac cone states (i.e. the energy
gap) at the Dirac point in the photoelectron spectra has shown the dependence of the measured
gap on the synchrotron radiation polarization (about 28-30 meV for p-polarization and 22-25
meV for circularly polarized radiation of opposite chirality). The mechanism of opening the gap
at a Dirac point above the Tn was proposed due to the “pairing” of the Dirac fermions with
opposite momentum and spin orientation as a result of their interaction with the spin texture
generated by photoemission in the region of the photoemission hole on a magnetic impurity atom
(Gd). It was shown that the gap at the Dirac point, measured above Tn, is dynamic and is formed
directly during photoemission process. At the same time, the origin of the gap remains magnetic
(even when the long-range magnetic ordering is destroyed) and is associated with the properties
of the magnetic topological insulator that determines a practically unchanged size of the gap
above Tn. The dynamic origin of the generated gap is confirmed by the dependence
of its magnitude on the polarization of synchrotron radiation.
Влияние температур роста и постростового отжига на магнитные свойства наночастиц Mn-=SUB=-1+x-=/SUB=-Sb, внедренных в тонкие пленки GaSb
Authors: Дмитриев А.И. , Кочура А.В. , Кузьменко А.П. , Паршина Л.С. , Новодворский О.А. , Храмова О.Д. , Кочура Е.П. , Васильев А.Л. , Нехаева Е.И. , Аронзон Б.А.
Published: January 2020

The magnetic properties of two-phase granular semiconductor-ferromagnet GaSb–MnSb films obtained by pulsed laser deposition, depending on the temperature conditions of growth and postgrowth annealing, are investigated.
Методика измерений двойным зондом в электродном разряде с изменяющимися параметрами
Authors: Барышников А.С. , Басаргин И.В. , Безверхний Н.О. , Бобашев С.В. , Монахов Н.А. , Попов П.А. , Сахаров В.А. , Чистякова М.В.
Published: January 2020

Предложена методика корректировки сигнала двойного зонда при измерениях в плазме изменяющегося во времени электродного разряда. Методика проверена в экспериментах по взаимодействию ударной волны с поперечным тлеющим разрядом в режиме стационарного горения и распадающейся плазмы. Ключевые слова: двойной зонд, ударная волна, горение, тлеющий разряд.
Характеристики сильноточной электронной пушки с плазменным анодом на основе гибридного разряда
Authors: Кизириди П.П. , Озур Г.Е.
Published: January 2020

In the paper, the results of the study of space structure and temporal dynamics of a hybrid discharge matching a high-current reflective discharge with vacuum arcs initiated by surface dielectric flashover at the discharge supplying voltages up to 9 kV and working gas (argon) pressures of 0.1 – 1 mTorr are presented. The possibility of the formation of plasma anode with the density increased at the periphery including the use of an auxiliary screen has been demonstrated.
The measurements of energy density distribution of a low-energy, high-current electron beam formed in an electron gun with explosive-emission cathode and plasma anode based on this hybrid discharge are also presented. The results obtained are comparable with those achieved with the use of magnetic field concentrators. Since the use of concentrators is not always possible, so the suggested method of the beam uniformity improvement looks promising.
Десорбция положительных ионов металла с поверхности массивного анода на пластину цеолита
Authors: Орбух В.И. , Лебедев Н.Н. , Агамалиев З.А. , Эйвазова Г.М. , Саламов Б.Г.
Published: January 2020

Рассмотрено явление переноса положительных ионов металла с поверхности массивного анода на поверхность цеолитовой пластины в аномально малом для этого явления внешнем электрическом поле. Объяснение наблюдаемого явления основано на том, что в электрическом поле на проводящих порах цеолита вблизи анода возникает отрицательный заряд, локализованный на стенках пор, создающий аномально большое локальное электрическое поле на поверхности анода. Это поле осуществляет перенос ионов с анода на поверхность цеолита. Приведены соображения, объясняющие пороговый (по величине внешнего поля) характер явления. Ключевые слова: цеолит, ионный обмен, ионы серебра, массоперенос.
Характеристики апконверсионной люминесценции порошков CaF-=SUB=-2-=/SUB=- : Er при возбуждении лазерным излучением с длиной волны 1.5 μm
Authors: Ляпин А.А. , Рябочкина П.А. , Гущин С.В. , Жарков М.Н. , Ермаков А.С. , Кяшкин В.М. , Прытков С.В. , Атанова А.В.
Published: January 2020

The characteristics of upconversion luminescence of CaF2:Er crystalline powders were investigated upon excitation of Er3+ ions to the 4I13/2 level by laser radiation at 1531.8 nm. The energy yield values of upconversion luminescence were determined for the spectral ranges 380–780 and 380–1100 nm. It was found that upconversion luminescence of CaF2:Er powders with concentrations of 0.5, 2, 4, 6, 8, 10, 11, 13, 15, and 17% of Er3+ ions is characterized by correlated color temperatures of about 5100, 2142, 1726, 1738, 1773, 1757, 1762, 1765, 1735, and 1714 K, respectively.
Акустооптические свойства сплавов на основе германия, селена, кремния и теллура
Authors: Хоркин В.С. , Волошинов В.Б. , Ефимова А.И. , Кулакова Л.А.
Published: January 2020

We examined the acoustical, optical and acousto-optical properties amorphous alloys based on germanium, selenium, silicium and tellurium. The phase velocities of longitudinal acoustic waves and the value of acousto-optic figure of merit of the tellurium-based compounds were measured using the infrared sources of light radiation on the wavelength λ = 3.39 μm. We measured the acousto-optic figure of merit of germanium single crystal in case of diffraction on the acoustic modes along [110] and [111].
Электролюминесценция анодного оксида алюминия в кетонах
Authors: Овеченко Д.С. , Бойченко А.П.
Published: January 2020

The film of aluminum oxide formed by electrolysis in distilled water demonstrated the possibility of generating its electroluminescence in ketones and related compounds containing carbonyl groups. For acetone, cyclohexanone, methylpyrrolidone, acetylacetone, 4-ethylpropiophenone and 4-methoxypropiophenone, it was established that this process proceeds without electrolysis of the above compounds. It was shown that at constant voltage and temperature, the brightness-kinetic characteristics of luminescence are significantly affected by a combination of the following factors: the structure and elemental composition of hydrocarbon radicals of ketones, the number of carbonyl groups at these radicals, the thickness and structural organization of Al2O3 oxide films, on the surface of which local amplification is possible electric field strengths up to values of the order of 10^6 V/m, sufficient to initiate and maintain ionization processes leading to generation light.
Морфология и структурное состояние частиц нанопорошков, полученных измельчением природного алмаза и методом детонационного синтеза
Authors: Шарин П.П. , Сивцева А.В. , Попов В.И.
Published: January 2020

A complex of high-resolution methods has revealed that the nanopowder particles obtained by milling natural diamonds have a wider variety of sizes and predominantly of lamellar shape in contrast to detonation synthesis nanopowder, which consists mainly of similar-sized and isometric particles. The primary particles of the nanopowder obtained by milling, as well as detonation synthesis nanodiamonds, consist of diamond nuclei with cubic crystal lattices surrounded by shells with complex structures, which are formed from carbon atoms in the sp2-state and impurities. A noticeable increase in interatomic distances in nanodispersed diamond crystals has been established compared with those for large diamond crystals.
Экспериментальное исследование и моделирование спектральных характеристик светодиодных гетероструктур с активной областью из InAs
Authors: Семакова А.А. , Липницкая С.Н. , Мынбаев К.Д. , Баженов Н.Л. , Кижаев С.С. , Черняев А.В. , Стоянов Н.Д. , Lipsanen H.
Published: January 2020

Spectral characteristics of InAs-based light-emitting diode (LED) heterostructures for the mid-infrared spectral range were studied both experimentally and theoretically, with the use of MATLAB software, and also modeled in COMSOL Multiphysics®. By comparing the results of experiments, calculations and modeling, a pattern of the formation of emission spectra of heterostructures was obtained. The obtained results confirm the prospects for the use of modeling in the design of LED structures.
Новый подход к экспериментальному исследованию больших ансамблей радиотехнических генераторов со сложными связями
Authors: Кульминский Д.Д. , Пономаренко В.И. , Сысоев И.В. , Прохоров М.Д.
Published: January 2020

A new approach is proposed that allows one to investigate experimentally complex dynamics in large ensembles of coupled radio engineering generators. The approach is used for the construction of an analog-to-digital experimental setup for studying ensembles of generators with time-delayed feedback. A possibility of specifying an arbitrary architecture of couplings and different types of couplings between generators is implemented in the setup. It is shown that the complex topology of couplings and parameters of all generators can be reconstructed from their experimental time series.
Электронный спиновый резонанс многослойного графена, синтезированного с полистиролом
Authors: Семенихин П.В. , Ионов А.Н. , Николаева М.Н.
Published: January 2020

The temperature and magnetic field dependences of electron spin resonance was investigated for a graphite / polystyrene composite. The obtained value for the g-factor does not depend on temperature and is equal to 2.003, which is close to the value for a free electron for carbon (g = 2.0022-2.0035). This behavior of the g-factor excludes the possibility of an internal magnetic field in the composite.
Kinerja Karyawan Klinik Syifa Medical Center Jakarta Ditinjau dari Kompensasi, Motivasi Kerja, dan Budaya Organisasi
Authors: Utama M. Fathan Nugrah , Sampurno Sampurno , Djoharsyah Djoharsyah
Published: January 2020

Telah dilakukan penelitian pengaruh variabel kompensasi, motivasi kerja dan budaya organisasi untuk mengetahui bagaimana pengaruhnya terhadap kinerja karyawan di Klinik Syifa Medical Center. Sampel yang digunakan dalam penelitian ini sebanyak 152 responden dengan teknik pengambilan sampel yaitu nonprobability sampling dan purposive sampling. Pengambilan data menggunakan kuesioner dengan pengukuran skala likert. Hasil penelitian menunjukkan bahwa kompensasi memberikan pengaruh signifikan terhadap kinerja karyawan sebesar 22.2%, variabel motivasi kerja memberikan pengaruh signifikan terhadap kinerja karyawan sebesar 31.1%, variabel budaya organisasi memberikan pengaruh signifikan terhadap kinerja karyawan sebesar 18.4%, pengaruh variabel kompensasi, motivasi kerja dan budaya organisasi terhadap kinerja karyawan berpengaruh secara signifikan sebesar 32.6%.
Nilai Antioksidan dan Spf dari Kombinasi Minyak Biji Wijen (Sesamum indicum L.) dan Minyak Biji Bunga Matahari (Helianthus annuus L.)
Authors: Susanti Yanthy , Purba Anny Victor , Rahmat Deni
Published: January 2020

Minyak wijen dan minyak biji bunga matahari yang mengandung Vitamin E dan β-Karoten dilaporkan memiliki aktivitas antioksidan dan tabir surya. Penelitian aktivitas tabir surya pada minyak wijen memberi hasil nilai SPF sebesar 1,77. Tujuan penelitian ini adalah untuk mendapatkan kombinasi minyak wijen dan minyak biji bunga matahari yang memiliki aktivitas antioksidan dan nilai SPF yang optimal. Metode yang digunakan untuk mengukur aktivitas antioksidan dengan metode peredaman radikal bebas, nilai SPF diperoleh dengan menghitung harga AUC kurva hubungan antara panjang gelombang dengan serapan yang dihasilkan. Hasil penelitian menunjukkan minyak wijen memiliki aktivitas antioksidan (IC50) sebesar 267 µg/mL dan nilai SPF sebesar  1,46 pada konsentrasi 125µg/mL, minyak biji bunga matahari memiliki aktivitas antioksidan (IC50) sebesar 88,37 µg/mL dan nilai SPF 1,14 pada konsentrasi 125µg/mL, kombinasi kedua minyak memiliki aktivitas antioksidan sebesar (IC50) sebesar 118,04 µg/mL dan nilai SPF 1,78 pada konsentrasi 125µg/mL.
Urban sediment in infiltration wells: A lesson from the northern area of greater Yogyakarta city
Authors: Suprayogi Slamet , Sudarmadji Sudarmadji , Malawani Muhammad Ngainul
Published: January 2020

The development of housing in Yogyakarta eventually led to increased levels of runoff. To mitigate runoff increases, infiltration wells were constructed in a specific network. The northern part of Yogyakarta is now facing urbanization, and there are many housing blocks that are being constructed complete with the runoff drainage system. This study aims to reveal the role of the infiltration wells network about runoff and its effectiveness concerning the sediment load in the urban area. The drainage networks in the research area function as a watershed, but not with a single outlet. The runoff flow was spreading through the drainage system and did not accumulate on the single outlet. It can be seen that some infiltration wells supposed as a well, which is a place of accumulation of runoff and sediment.  Most of the infiltration wells have been filled with sediment up to over a quarter, or even more than half, of their carrying volume. Granulometry measurement shows that the percentage of clay, loam, sand, and gravel in each well tend to differ for every sample. The differences between filled wells and their sediment grain depend on the location of those wells. Maintenance of the wells is required, such as sediment dredging, to rejuvenate them and improve their efficiency.
Contesting the Social Spaces: Gender Relations of Literary Communities in Yogyakarta and Surakarta
Authors: Udasmoro Wening , Anwar Saeful
Published: January 2020

This research seeks to map the gender relations within literary communities and their contestations in gaining social and financial capital in Yogyakarta and Surakarta social spaces. The presence of literary communities in these spaces, on the one hand, explains the local and specific self-identities of the communities, as well as their heterogeneity in gender relations. In particular, this research maps these communities' differences in expressions, trajectories (visions for the future), themes, narrations, language, and networks based on their gender relations. The Geographic Information System (GIS) method is used to map and explore the gender issues in these literary communities. By understanding the mapping of these literary communities, the dynamics of the social spaces used by these communities can be traced synchronically within a specific period. It can also be followed up when the database is used diachronically over time. This research finds that social spaces that enable open narration are insufficient to ensure the equality of women and men. Flexible domestic spaces for women are also necessary to ensure women to be active in creating the trajectory of the literary communities since they have capacities to do it.
Improving Numerical Weather Prediction of Rainfall Events Using Radar Data Assimilation
Authors: Hastuti Miranti Indri , Paski Jaka Anugrah Ivanda , Fatkhuroyan Fatkhuroyan
Published: January 2020

Data assimilation is one of method to improve initial atmospheric conditions data in numerical weather prediction. The assimilation of weather radar data that has quite extensive and tight data is considered to be able to improve the quality of weather prediction and analysis. This study aims to investigate the effect of assimilation of Doppler weather radar data in Weather Research Forecasting (WRF) numerical model for the prediction of heavy rain events in the Jabodetabek area with dates representing four seasons respectively on 20 February 2017, 3 April 2017, 13 June 2017, and 9 November 2017. For this purpose, the reflectivity (Z) and radial velocity (V) data from Plan Position Indicator (PPI) product and reflectivity (Z) data from Constant Altitude PPI (CAPPI) product were assimilated using WRFDA (WRF Data Assimilation) numerical model with 3DVar (The Three Dimensional Variational) system. The output of radar data assimilation and without assimilation of the numerical model of WRF is verified by spatial with GSMaP data and by point with precipitation observation data. In general, WRF radar assimilation provides a better simulation of spatial and point rain events compared to the WRF model without assimilation which is improvements of rain prediction from WRF radar data assimilation would be more visible in areas close to radar sources and not echo-blocked from fixed objects, and more visible during the rainy season
Digging Deeper into Dialogic Feedback: Evaluating How Science Teachers Manage Uncertainty as a Predictor of Students’ Ability to Construct an Epistemically Sound Argument
Authors: Kuhn Mason , Pepanyan Marine
Published: January 2020

In this study, we examined the relationship between the use of two teachers’ dialogue feedback as an educational practice to promote evidence-based argumentation in middle school science lessons and the students’ ability to create scientific arguments in a standardized critical thinking exam. The teachers had an equal amount of training on Argument-Based Inquiry (ABI) and taught in a federally-identified low-income school. When the patterns of talk were analyzed, divergent themes emerged and feedback that promoted critique correlated with student achievement on the critical thinking exam.
A Study on Sources, Availability and Accessibility of Potable Water in Imo State, Nigeria
Authors: Iwuala Chimezie C. , Amadi Agwu N. , Udujih Obinna G. , Udujih Helen I. , N. Okereke, S.
Published: January 2020

Sources, availability and accessibility of potable water were studied in the three geopolitical zones; Okigwe, Owerri, Orlu zones of Imo State, Nigeria. A total of 800 pretested and randomly distributed questionnaires were used on adult respondents in the three zones. Results identified borehole water as the major (65.4%) source of drinking water among the respondents. More than half (53.8%) of the respondents have their water source located less than 50m from their houses, of which 33% have their boreholes located within their compounds. About half of the respondents visit water bodies daily. The highest total rating of supply of water by the respondents was on “poor” supply. The poor rating was more in Okigwe zone where 107 (64.7%) gave poor rating for supply of potable water. The study has shown that although there is availability and accessibility of water, there is need to monitor sitting of water sources and create awareness as well as lay emphasis on purification since what is available and accessible is not potable.
An algorithm for wavelet thresholding based image denoising by representing images in hexagonal lattice
Authors: K. M Jeevan , Krishnakumar S.
Published: January 2020

The existing method of representation for digital images is using square shaped picture elements called pixels in a rectangular grid. Processing based on hexagonal grid is a new approach in image processing. It has various advantages like symmetry, higher angular resolution, consistent connectivity and higher sampling efficiency. Image processing applications like rotation, scaling, edge detection, and compression in hexagonal domain have already been discussed by many researchers. In this paper we propose an image denoising scheme in hexagonal lattice using wavelet thresholding method. For the thresholding of wavelet coefficients, modified NeighShrink thresholding method is applied. In NeighShrink method, sub-optimal universal threshold and identical neighboring window size in all wavelet sub-bands are used. However, in the proposed method, instead of sub-optimal universal threshold, an optimal threshold is determined for every wavelet sub-band by the Stein’s Unbiased Risk Estimate (SURE). Denoising is performed on images represented in rectangular grid as well as hexagonal grid using modified thresholding method for comparison. MSE, PSNR and SSIM are used for the performance analysis. The obtained results confirm that the proposed method gives better results than existing algorithms.
Fixed grid wavelet network segmentation on diffuse optical tomography image to detect sarcoma
Authors: Maheswari K. Uma , Sathiyamoorthy S.
Published: January 2020

Objective: To detect and explore the boundary of the sarcoma in Diffuse Optical Tomography (DOT) images, we need to extract the scattering and absorption property of the tissue at the cellular level. The DOT images suffer with lower optical resolution; therefore to improve the resolution in non-invasive imaging technique we apply Fixed Grid Wavelet Network (FGWN) image segmentation. Methods: We have subjected the reconstructed optical image to Vignette Correction to enhance the corners so that it traces the smooth boundary of tumor region. Fixed Grid Wavelet Network segmentation applied to reduce the training with the significant ortho-normal property. R, G and B values of optical image were considered as network inputs which lead to the formation of Wavelet network. Effective wavelet selection was based on Orthogonal Least Squares Algorithm and the network weights were calculated to optimize the network structure. The Mexican hat wavelet chosen facilitates the diffusion operator for image restoration, hence well-suited for Diffuse Optical Tomography (DOT) images.Results: Analysis made on data base of 30 DOT images and the 6 criteria results was evaluated. The boundary of the tumor region was traced on grayscale and the following Image Metrics were measured namely Mean Square Error, Root Mean Square Error, Peak Signal to Noise Ratio, Pearson Correlation Coefficient and Mean absolute error. The Receiver Operating Characteristics (ROC) was estimated at 99.527%, 88.73% and 93.8% with respect to sensitivity, specificity and overall accuracy. Conclusions: FGWN was compared with genetic algorithm and graph cut segmentation based on image metrics which exhibited 5.2% improvement and it was evaluated such that FGWN based image segmentation was superior to other methodologies.
Microwave sintering of tungsten heavy alloys
Authors: Prabhu G. , Sankaranarayana M. , Nandy T. K.
Published: January 2020

To understand microwave sintering of heavy alloys with high tungsten content, 93W-4.9Ni-2.1Fe alloy was sintered using a 6 kW, 2.45 GHz microwave sintering furnace at 1783 K (1510˚ºC) and 1793 K (1520˚ºC). The alloy sintered at 1793 K (1520˚ºC) achieved full densification and had improved microstructural features, superior mechanical properties compared to 99.4% densification and relatively inferior properties obtained in the alloy sintered at 1783 K (1510˚ºC). This study also includes a comparison between microwave sintered and conventionally sintered 93W-4.9Ni-2.1Fe alloy (sintered at 1793K (1520ºC)). Contrary to the full densification and superior mechanical properties obtained in microwave sintering, conventional sintering at 1793K (1520ºC) resulted in only 99.6% densification and substantially inferior properties. Analyses of microstructure and fracture surface revealed that key microstructural parameters such as tungsten grain size, tungsten-tungsten contiguity, matrix volume fraction and also the fracture mode were significantly different between the alloys processed by the two routes. Possible reasons behind dissimilar densification, significantly different microstructures and mechanical properties obtained between these two modes of sintering, are also discussed in this study.
Micro-structural analysis and elastic properties of oil palm trunk fibre reinforced polyester composites
Authors: Anyakora Anthony N. , Abubakre Oladiran K.
Published: January 2020

This work addressed the study of development of micro-structure as related elastic properties in oil palm trunk fibre reinforced polyester composites. The results show that the Modulus of Elasticity value for the treated oil palm trunk fibre laminate was 67.43MPa at 70% fibre content, while the Modulus of Rigidity was 335.76MPa at 70% fibre content. The cross-sections of the specimens examined by Scanning Electron Microscopy indicated that the failure pattern of treated fibre composites was gradual, and related to the stiffness prominence. It was deduced that the knowledge of relationship between micro-structure and elastic properties could compliment the findings of effect of fibre loading, alkaline and silane treatment processes in the utilization of oil palm trunk fibre composite for any desired engineering application.
Comparative study on natural and reactive dye for cotton coloration
Authors: Repon Md. Reazuddin , Islam M. Tauhidul , Mamun Md. Abdullah Al , Rashid Muhammad Abdur
Published: January 2020

Eco-friendly textile dyeing with natural dye is a global soaring interest for avoiding environment pollution incurred by synthetic dyes. This study attempts to compare the dyeing properties of cotton knitted fabric dyed with banana floral stem (BFS) sap and reactive dye. Natural dye i.e. BFS sap was extracted from the species of Musa sapientum by roller squeezer machine. The recipe of reactive dyeing was selected to match the exact shade with the natural dyed specimens. Conformation of the dye molecule fixation onto fiber surface was assured by FTIR-ATR spectra. Comparative analysis were carried out in response of degree of color levelness, color fastness to water, washing, perspiration, rubbing, light and effluent qualities. The economic viability of natural dyeing was also estimated. The specimens dyed with BFS sap have excellent color levelness and color durability characteristic alike reactive dye except light fastness properties. Moreover, natural dyeing costs were almost half of the reactive dyeing. Finally, this inquiry forecasts a less time, energy and water consuming, economical and ecofriendly dyeing process which could be deployed as replacement of reactive dyes with a few compromises.
Surface Area and Porosity Development on Granular Activated Carbon by Zirconium: Adsorption Isotherm Studies
Authors: Achari V. Sivanandan , Rajalakshmi A. S. , Jayasree S. , Lopez Raichel Mary
Published: January 2020

In this study, a new series of coconut shell based granular activated carbons (GAC) are prepared by impregnating with zirconium ions as zirconyl chloride and activated under superheated steam. These carbons are designated with activation temperature/ conditions as GAC 383 (activated at 383K), GACO 383 (HNO3 oxidised), GACZR 1273 (ZrOCl2 activated at 1273K) and GACOZR 1273 (HNO3 oxidised, ZrOCl2 activated at 1273K). Surface characteristics of these carbons are evaluated using Boehm titration methods, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction techniques (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The pore volume and the respective specific surface area of each carbon are determined by BET, I plot, Langmuir, Freundlich, and Dubinin-Radushkevich isotherms using N2 adsorption data at 77K. Analysis shows that zirconium ion enhances the surface area and porosity of granular activated carbon. The adsorption characteristics of newly prepared GAC are tested by solid-liquid equilibria using phenol as adsorbate. Equilibrium phenol adsorption data fitted to standard isotherm models of Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) equations. Adsorption constants and parameters indicate that zirconium impregnated granular activated carbons are relatively more efficient for the removal of phenol than the native carbon used.
Experimental and simulation studies on gasification characteristics of a low-rank coal by rapid heating under CO2-rich condition
Authors: Cong Wang , Alade Olalekan S. , Sasaki Kyuro , Sugai Yuichi
Published: January 2020

In this investigation, an environmentally benign and efficient way for gasification of low-rank coal under CO2 rich condition, rapid heating, and high pressure was investigated. Series of experimental and simulation studies were carried out to compare the combustion characteristics of the Shandong (SD) low rank coal and Datong (DT) bituminous coal. It was found that the gasification potential of the SD coal sample was higher than that of the DT coal sample under the conditions investigated. A gasification model was developed and validated to predict the gasification characteristics of the low rank coal based on the experimental and the gasification kinetic parameters. It was found that the gasification conditions resulting in effective gasification of the low rank coal (in terms of CH4, CO and H2 gases production) are 100% CO2 concentration, 37.5 J/s heating rate, and 0.5 – 1 MPa pressure range.
Optimization on Dry Sliding Wear, Electrical Resistivity and Mechanical Properties of Cu–4Cr–xZrC Composites
Authors: Singh S. Christopher Ezhil , Selvakumar N. , Flower T. Mary Little
Published: January 2020

This present study is to develop statistical model that might be used to predict the wear properties of Cu - 4Cr - xZrC (x = 0-8 wt. % of ZrC) composites have faith in densiﬁcation of the powder throughout compaction and sintering. The inﬂuence of the reinforcement, sliding distance and load on Specific Wear Rate (SWR) and Coefﬁcient of Friction (COF) were studied using pin-on-disc machine. L27 orthogonal array was selected for investigating the full factorial design using three factors with one replicate. Based on the main effects plots and interaction plots obtained through design was studied. Analysis of Variance (ANOVA) was used to explore the inﬂuencing input parameters on SWR and COF. The hardness of the composites will increase because of the increase in wt. % of ZrC. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), pin on-disc system, Four point probe tester and Rockwell hardness tester were used to evaluate the characterization, tribological properties, electrical resistivity and hardness respectively of Cu-4Cr-xZrC composites respectively. The level of each parameter is fixed at three totally different levels, namely low, medium and high. Mathematical model was applied by design expert software so as to precise the influence degree of the most wear variables like reinforcement, sliding distance and load on SWR and COF respectively. The results indicate that the reinforcement is more dominant factor affecting SWR and COF mainly. The reinforcement plays an important role than sliding distance and load. The morphology of the worn out surfaces was analyzed to know the wear mechanisms.
Physicochemical and mechanical study of Mayan Archeological stony constructive materials
Authors: Paredes V. J. Ley , Uc J. M. Cervantes , Pacheco E. Perez , Soberanis C. R. Ríos , Wakayama S.
Published: January 2020

Mayan civilization monumental architecture has been a vital source of information to gain acknowledgement about its way of life, science and political hierarchy; consequently, examination of constructive materials of Mayan structures by using materials science characterization techniques are noteworthy. This work focuses on the study and characterization of archeological stony materials taken from the main structure on Witzinah archeological site located south of Yucatan, Mexico, in order to determine its constituted elements and chemical components. Such materials were observed under scanning electron microscopy (SEM) to establish, in accord to its micro-structural patterns, the porosity and morphology, and energy-dispersive X-ray spectroscopy (EDX) to determine the chemical compounds. Calorimetric analysis through TGA was carried out in order to identify the presence of organic elements as well as Infrared analysis (FTIR) and nuclear magnetic resonance (1H NMR) to detect polymeric components. Preliminary results indicated that mortars contain saturated fats (esters) that were possibly originated by degradation of natural polymer (elastomeric rubber) known as polyisoprene as well as nano-clay material named Palygorskita (typified in Maya as Sak lu’um), and that both had a direct influence on the properties of the evaluated mortars used for the construction of the site Principal Building.
Photocatalytic degradation of Bisphenol A: Kinetic studies and determination of the reaction pathway
Authors: Rodríguez Luis F. Garay , Zermeño Brenda , De la O Karla Alejandra López , Leyva Elisa , Moctezuma Edgar
Published: January 2020

The photocatalytic degradation of BPA aqueous solutions with commercial TiO2 (Evonik P25) was carried out in a home-made batch reactor illuminated with four UV lamps (λmax= 365 nm) in order to determine the kinetic parameters of the reaction rate equation and to identify and quantify some of the most stable aromatic intermediate reaction products. Low concentration (20 ppm) BPA solutions were completely degraded and mineralized in less than three hours of reaction. Whereas, BPA aqueous solutions with concentration above 50 ppm are transformed in other chemical compounds in 6 hours of reaction and fully mineralized in 15 hours of reaction. Kinetic analysis of the experimental results of BPA concentration as a function of time indicated that this photocatalytic degradation process follows a LH-HW reaction rate law where the reaction order shift from zero order to first order as the reactant concentration is decreased. Analysis of the reaction samples by different analytical techniques indicated that BPA is mineralized via formation of hydroquinone, benzoquinone, benzene-triol, catechol, and phenol by two simultaneous reaction pathways.
Optimization of thermal efficiency of a parabolic trough solar collector (PTSC) based on new materials application for the absorber tube selective coating and glass cover
Authors: Jamali Hamzeh
Published: January 2020

This article aims to demonstrate a solution in order for an optimization of PTSCs thermal efficiency. The solution focuses on the radiative heat transfers occurring within the absorber tube of a PTSC unit of a solar power plant situated in Shiraz, Iran as the paper case study. Since the existing heat transfers procedure all comes down to the optical properties of the materials used in the absorber tube of a PTSC unit, an ideal material selection can directly influence the heat transfers and consequently improve the thermal efficiency of a PTSC unit to a great extent. This paper comes up with new materials selection in which graphene nanostructure and BOROFLOAT 33 are respectively used as absorber tube coating and absorber tube glass cover for their exceptional optical and mechanical properties. Meanwhile, a numerical and analytical comparison is made between the thermal efficiencies of a PTSC unit in different states.
Nanocolumnar CdS thin films grown by glancing angle deposition from a sublimate vapor effusion source
Authors: Daza L. G. , Rodríguez R. Castro , Carrillo M. Cirerol , Tovar E.A. Martín , Gamboa J. Méndez- , Esquivel R. Medina , Quintana I. Perez , Iribarren A.
Published: January 2020

The glancing angle Deposition (GLAD) technique was used to grow cadmium sulfide (CdS) thin films on glass and indium tin oxide (ITO) coated glass substrates from a sublimate vapor effusion source. The samples were prepared under different incident deposition flux angles (a) of 0°, 20° and 80°, while both the substrate and the source were under rotation. The temperature of the source was 923.15 K. Scanning electron microscopy images showed that the GLAD method combined with the source produced dense nanocolumnar shaped structures with height and diameters of ~200 and ~30 nm respectively. The deposited films showed a hexagonal structure with preferential (002) plane orientation and crystallites sizes between ~25 nm and ~35 nm. A maximum solar weighted transmission of ~92% was obtained for the sample prepared at a =80°, with a substrate/source rotation velocity ratio of 55/20 in the wavelength region of 400-900 nm. The average band gap energy of the films was 2.42 eV. Refractive indexes between ~1.4 and ~2.4 at a 550 nm the wavelength were also obtained.
Amine modified kaolinite clay from Nigeria: A resource for removing Cd2+ and Pb2+ ions from aqueous solution
Authors: Adewuyi Adewale , Pereira Fabiano Vargas , Adewuyi Omotayo Anuoluwapo
Published: January 2020

Kaolinite clay (KC) obtained from redemption camp; Nigeria was modified by surface grafting and investigated for the removal of Pb2+ and Cd2+ ions from aqueous solution by adsorption. KC and the modified kaolinite clay (MKC) were characterized using X-ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analyzer, Fourier Transform Infrared spectrometer (FTIR), Particle Size Distribution (PSD), zeta potential, elemental analysis (CHNS/O analyzer) and Energy Dispersive Spectroscopy (EDS). Equilibrium, thermodynamics and kinetic studies were conducted by considering the effects of pH, initial metal ion concentration, contact time, adsorbent weight and temperature. Modification of KC increased its equilibrium adsorption capacity from 8.01 mg/g for Cd2+ and from 24.75 mg/g to 36.41 mg/g for Pb2+ ions. The adsorption process obeys Freundlich and Temkin isotherms. The adsorption was second-order-kinetic and controlled by both intra-particle and liquid film diffusion. Values of ΔGo, ΔHo, and ΔSo, for KC an MKC showed a stable adsorbent-adsorbate configuration.
Compartive study on performance of the LDPC codes and turbo-codes used in the image transmission in the gaussian and rayleigh channel
Authors: Menezla Fayssal , Meliani Rachida , Mahdjoub Zoubir
Published: January 2020

The errors induced by channel noise influence on the quality of digital transmission. The latter depends on the probability of errors in the transmitted symbols. To control these errors, a technique of digital signal processing is used, including the information code to be transmitted. As these techniques are used for controlling the transmssion, they are called "channel encoding". In this paper, we introduced and studied two major correction code families' error; LDPC (Low Density Parity Check) and the turbo code. We used our simulation model to evaluate the performance of a Gaussian channel. The results show the effect of iterative LDPC and Turbo code on the transmission and quality of information. Our numerical simulation has shown that the resulting image was corrected gradually as the number of iterations increases for both channels. On the Rayleigh channel, the image correction is obtained for a higher number of iterations over the Gaussian channel.
Density distribution effect on the analysis of the 6Li+ 58Ni reaction
Authors: Torabi Fatemeh , Reyes Elí Francisco Aguilera
Published: January 2020

The effect of density variation on the optical-model (OM) analysis of 6Li + 58Ni is investigated by using bare potentials extracted from different density distributions of the weakly-bound 6Li nucleus. For each of the bare potentials, the real and imaginaru parts of the direct-reaction and fusion polarization potentials are deduced from respective X2 fittings to the elastic scattering and fusion data. The results obtained show that variations in the density distribution of the weakly-bound projectile can change the strengths of the dynamic direct-reaction polarization potential, however, it cannot make a noticeable difference on the OM predictions of fusion cross sections.
Methylene blue degradation assessment by advance oxidation methods
Authors: Sierra B. Jaramillo , Cabrera A. Mercado , Arias A. N. Hernández , Eguiluz R. Peña , Callejas R. López , Méndez B. G. Rodríguez , Alvarado R. Valencia
Published: January 2020

Experimental investigation about methylene blue degradation in aqueous solution applying several Advanced Oxidation Processes such as O3, O3/H2O2, O3/UV and O3/UV and O3/UV/H2O2 was accomplished. Methylene blue treatment consisted in evaluating the degradation of an initial concentration of 22 ppm in 500 ml of aqueous solution. The contaminant degradation of an initial concentration of 22 ppm in 500 ml of aqueous solution. The contaminant degradation efficiencies were analyzed considering parameters such as: treatment time, three different pH values for the solution and O3 and H2O2 as oxidizing reagents. The discoloration of the samples was examined throughout the experimental each 10 minutes. Using O3/UV/H2O2 (10 ppm) with an initial 7 pH and a treatment time of 60 minutes the highest degradation efficiency of 98% was achieved.