bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic even-harmonic generation due to symmetry-breaking effects induced by spatially inhomogeneous field*
Authors: Guo Yue , Liu Aihua , Wang Jun , Liu Xueshen
Published: August 2019

We ab initio investigate the interaction between the hydrogen atom and the inhomogeneous field which is induced by resonant plasmons within a metal nanostructure. Same as normal laser pulse (homogeneous field), only odd-harmonic generation occurs when the bow-tie nanostructure is utilized. For the single nanotip case, the even-harmonic generation can be distinctly found in the harmonic emission spectrum. By investigating the symmetry and trajectories of different inhomogeneous fields, we demonstrate that the breaking symmetry of system can enable even high harmonic generations.
Diode-pumped Kerr-lens mode-locked Ti: sapphire laser with broad wavelength tunability*
Authors: Liu Han , Wang Geyang , Yang Ke , Kang Renzhu , Tian Wenlong , Zhang Dacheng , Zhu Jiangfeng , Han Hainian , Wei Zhiyi
Published: August 2019

We report a direct blue-diode-pumped wavelength tunable Kerr-lens mode-locked Ti: sapphire laser. Central wavelength tunability as broad as 89 nm (736–825 nm) is achieved by adjusting the insertion of the prism. Pulses as short as 17 fs are generated at a central wavelength of 736 nm with an average output power of 31 mW. The maximum output power is 46.8 mW at a central wavelength of 797 nm with a pulse duration of 46 fs.
Contrasting the evolution of moderate and extreme positive Indian Ocean Dipole events
Authors: Hermawanto A. , Wu Lixin , Mamenun
Published: August 2019

A recent study suggested, due to greenhouse warming, the frequency of extreme positive IOD (pIOD) events will increase in the future However, there is no information about the different character between extreme and moderate events During the period of 1979-2014, we identified 3 extreme and 4 moderate events Based on composite analysis of surface wind, sea surface temperature (SST) and temperature of the upper ocean, it is indicated there is a distinction on temporal and spatial evolution of equatorial easterly wind anomaly (EEWA) and the mean depth of 20°C isotherm (thermocline) over the eastern part of the equatorial Indian ocean The EEWA was started around June (October) and retreat in November for extreme (moderate) events The thermocline of extreme (moderate) events also showed an earlier shallowing, started in May (October) and reached the most shallow of depth around November Indicating that, during extreme events, the positive Bjerkness feedback strengthened earlier Using mixed layer heat budget analysis, it is revealed that during moderate events, the ocean dynamic process dominantly influences the cooling process of SST only in the peak phase, while during extreme events, the ocean dynamic process has dominant role in the whole process (from initial until peak phase) The early coupled process of EEWA and thermocline in shaping strong SST cooling gives time for us to monitor the developments of extreme pIOD and prepare mitigation against the impact at the peak phase However, the results presented in this study are based on limited samples from observations, thus requiring further clarification with numerical models and analysis of ensemble long integrations.
The dynamics of negative Indian Ocean Dipole (nIOD) and its relation to the anomalous high rainfall in West Java Province, Indonesia
Authors: Hatmaja R B , Rusmanansari A H , Radjawane I M
Published: August 2019

West Java Province is the most vulnerable region to hydro-meteorological disasters (i.e. flood and landslide) in Indonesia. One of the main causes of these disasters is high level of rainfall. There were many global phenomena caused an increase in rainfall level in Indonesia, one of them was the Indian Ocean Dipole (IOD), especially its negative phase. By using the Dipole Mode Index (DMI), IOD strength or intensity can be determined. Besides, the composite analysis of anomalous sea surface temperature (SST), wind, and rainfall were constructed to examine the dynamics of the negative IOD and its relation to the high rainfall level in West Java. During the negative IOD (nIOD), the significant positive (negative) anomalous SST appeared around May in eastern (western-central) of Indian Ocean. The intensity of anomalous SST in the following months reached its peak in September and accompanied by strong anomalous north-westerly wind. Furthermore, the high SST and anomalous wind increased the convection activity in the southern Java Island, and consequently, the level of rainfall in West Java increased up to 8.92 mm/day and may lead the risk of hydro-meteorological disaster.
Comparison of Heat Flux Observation at Three Different Locations around Bandung, West Java
Authors: Junnaedhi I D G A , Muchtar K , Herho S H S , Kombara P Y , Fajary F R
Published: August 2019

We observed heat flux profiles at three different locations around Bandung, West Java. Heat flux values were calculated using the covariance method with the vertical flow and potential air temperature fluctuation parameters. Observations have shown diurnal patterns in the three observation locations. Increasing heat flux during morning time flux on all three location shows similar pattern, but decreasing heat flux on the afternoon varies between locations. Urban residential area of Dago shows the most distinct pattern, with a rapid decrease in the afternoon and also after midnight. We also compared observed heat flux data with estimate values using the Bulk Parameterization method. We found that the estimated heat flux was not able to produce values in accordance with the observation data. Wind shear factor and inadequate implementation of the Bulk Parameterization method were thought to causing poor estimation of surface heat flux in Bandung. Improvements in this method, especially on the bulk transfer coefficient and surface skin temperature, are necessary to get better estimation result.
Trend of rainfall over Indonesian major lakes from tropical rainfall measuring mission data
Authors: Hidayat
Published: August 2019

Establishing patterns of natural variability of water resources in lakes is important for water management. However, the availability of reliable data often becomes obstacles, especially in ungauged regions. Rainfall products from Tropical Rainfall Measuring Mission (TRMM) potentially fill this gap. The aim of this study is to assess the trend of rainfall over Indonesian major lakes using TRMM rainfall estimates to investigate the natural variability of rainfall over the lakes. TRMM 3B43 monthly data over the period of 1998–2017 obtained from Giovanni data portal maintained by NASA were used to assess the trend of rainfall over Indonesian major lakes. Rainfall correlation with El Niño-Southern Oscillation (ENSO) variability was also investigated using Southern Oscillation Index (SOI) and Multivariate ENSO Index (MEI). Trend analysis was carried out using Mann-Kendall test. Rainfall depths over Lake Laut Tawar in Sumatra tend to gradually decline, which is confirmed by the Mann-Kendall test. Result of the test of rainfall over all other investigated lakes on Kalimantan, Sulawesi, Papua, and Java indicate no trends except for that of Lake Paniai on Papua, which indicates an increasing trend.
Local Climate Zone classification for climate-based urban planning using Landsat 8 Imagery (A case study in Yogyakarta Urban Area)
Authors: Pradhesta Y F , Nurjani E , Arijuddin B I
Published: August 2019

Urbanization of the last decade contributed to the urban morphological changes in Yogyakarta Urban Area (YUA). These conditions have an impact on local climate zone variations. There is an urgent need for enhanced climate-based urban planning. This study aims to: 1) Classify the Local Climate Zone (LCZ) in YUA using the World Urban Database Access and Portal Tool (WUDAPT) method, and 2) develop climate-based urban planning recommendations of the classification results. WUDAPT method used in this research based on the concept of LCZ framework by utilizing Landsat 8 imagery. LCZ classification of the whole area is determined using random forest classifier algorithm by SAGA GIS. The results of this study indicate that there are 12 LCZs in YUA, consisting of 6 types of LCZ based on building type and 6 LCZs based on land cover type. The highest increase of LST are in LCZ 3 and LCZ 5. Consequently, there’s a change in diurnal temperature from low to medium. Therefore, the thermal comfort aspect define by four components of LCZ is important in YUA urban planning strategy.
Exposure of dryland Farming to the ENSO Phenomenon in Kebumen District
Authors: Utami T I , Handayani T , Kuswantoro
Published: August 2019

The impact of the ENSO phenomenon causes a shift in the pattern of rainy and dry season. This will affect the agricultural activities Kebumen regency, crop failure and decreased productivity are few of the results of such impacts. This study aims to find the exposure pattern of dryland agriculture in Kebumen regency towards ENSO phenomenon and its association with maize productivity. The Data used is the daily rainfall period of 1986-2016 from 32 observer rain stations. There are five parameters to identify exposures are early deviation and duration of a dry season, rainfall of the maize, the maize harvest, the number of rainy days in maize harvest and the method used is scoring and overlay. The pattern of high exposure to dryland agriculture tends to be in mountainous areas. The El Nino Period of 2015 does not result in dryland agriculture Significantly being exposed due to low exposure, while the La Nina period results in moderate to high exposure cleaning Because land does not require too much water. In the El Nino period of 2015, maize productivity tends to rise 43% from normal conditions. In the La Nina period in 2010, the productivity of maize dropped by 63% Compared to normal conditions.
Temporal and spatial variation of surface heat flux in Makassar Strait
Authors: Radjawane I M , Hatmaja R B , Manullang J F , Trilaksono N J
Published: August 2019

Indonesian Seas have an important role on the sea-air interaction in Indo-Pacific region. Makassar Strait is located in the center of Indonesian Seas and part of Indonesian Throughflow (ITF), which has been influenced due to the coupled ocean-atmosphere phenomenon in Pacific and Indian Oceans, such as monsoon, El-Niño Southern Oscillation (ENSO), and Indian Ocean Dipole (IOD). The temporal and spatial variation of surface heat flux in Makassar Strait has been evaluated using the multi satellite dataset from 1984-2009. The remote sensing data with resolution of 1° × 1° obtained from Objectively Analyzed air-sea Fluxes (OAFlux) produced by Woods Hole Oceanographic Institution (WHOI). The results show that there is a seasonal fluctuation of surface heat flux related to the wind monsoon. The variation of the shortwave radiation and latent heat flux give a large contribution to the net surface heat flux that associated with ENSO and IOD events. In Makassar Strait, the variation of shortwave radiation and sea surface temperature (SST) is in a good agreement with the El-Niño/La-Niña events. There is a time lag between surface heat fluxes with the ENSO events.
The Distribution of Rainwater Acidity in Bandung
Authors: Indrawati A , Tanti D Aries , Budiwati T , Sumaryati
Published: August 2019

Acidity value (pH value) of rainwater, are influenced by the concentration of anions and cations dissolved in rainwater and it was also influenced by several sources of pollutants emitted into the atmosphere. This research was conducted to determine the sources of pollutants that affect the pH value in Bandung. Sampling locations were conducted in 10 locations, both in Bandung City and Regency. We used data monthly averages of pH value from 2006 – 2015, to see the distribution of pH values in Bandung. As for knowing the effect of pollutant sources that affect the pH value, Cipedes area was chosen to represent urban areas from the sampling location. We used data anion and cation concentrations of SO4
2-, NO3
-, Cl-, NH4
+, Na+ and Ca2
+ in 2006 - 2015. The statistical method used for data process was PCA method. Result shows that pH value in Bandung fluctuated from 2006-2015, with the lowest average pH value in 2010 and 2014 was 5.2. From result of data processing with PCA gained 3 factors influencing pH value Bandung, which were Factor 1: SO4
2-, NO3
-, K+ and Mg2
+, Factor 2: Ca2+, and NH4
+, Factor 3: Cl- and Na+.
Identification of Potential Source Location of Sulfur at Urban Area Bandung using Conditional Probability Function (CPF)
Authors: Kurniawati S , Santoso M , Lestiani D D , Atmodjo D P D , Sari D K , Kusmartini I
Published: August 2019

Bandung area is known as the center of economic growth in West Java. Bandung is also surrounding by mountains, therefore the morphological form of its territory is like a giant bowl. The previous study showed that the concentration of Sulfur in air particulate matter from Bandung is high. The objective of this study is to examine the use of conditional probability function (CPF) to identify directions of Sulfur sources using data collected from Bandung. CPF method is an advanced tool that analyzes pollutant source contributions in relation to the winds at the site and has been applied to find source directions. Data collection were done by air particulate sampling using GENT Sampler for 24-hours, once a week in Bandung during 2012-2014. EDXRF technique was applied for Sulfur analysis. The CPF values for Sulfur presented in polar plots, for fine and coarse particles. From this polar plot, the contributions of Sulfur in fine particles were coming from all sectors in Bandung whereas, in coarse particles, Sulfur dominated from the northern sector of Bandung.
Bias correction of daily precipitation from downscaled CMIP5 climate projections over the Indonesian region
Authors: Amsal F , Harsa H , Sopaheluwakan A , Linarka U A , Pradana R P , Satyaningsih R
Published: August 2019

Global Climate Models (GCMs) have been the primary source of information for constructing climate scenarios, and they provide the basis for climate change impacts assessments of climate change for a range of scales, from global down to regional scale. Due to the coarse spatial resolution, the GCM outputs have to be downscaled to resolve the scale discrepancy between the resolutions required for impact assessments and the model’s resolution. However, it is important to bias-correct (BC) the raw climate projection outputs which ideally correct the discrepancy between a model’s climate and the observed historical climate. In this study the results of bias correction of daily precipitation over the Indonesian region from downscaled CMIP5 GCM climate simulations using an optimized configuration of the Regional Climate Model (RegCM) for a baseline period of 16 years (1990–2005) with respect to observation is discussed in detail. The statistical bias correction method validated in this study is based on the initial assumption that both observed and simulated intensity distributions are well approximated by the Gamma distribution and the correction is made by matching the quantiles of the Gamma cumulative distribution functions. Overall, the results suggest that when the bias-correction is applied on dynamically downscaled model, it improved the skill in simulating the precipitation over Indonesia and this is a useful tool for further regional downscaling studies.
The Characteristics of squall line over Indonesia and its vicinity based on Himawari-8 satellite imagery and radar data interpretation
Authors: Hidayat A M , Efendi U , Rahmadini H N , Nugraheni I R
Published: August 2019

Squall line is a rare MCS phenomenon happened in Indonesia. In these recent years, radar showed the existence of squall line pattern on 31 December 2017, 25 and 27 January 2018 in disparate spot in Indonesia. This study aims to find the common characteristic of squall lines that occurs in tropical region of Indonesia. The result shows a persistent elongated convective pattern with the trailing stratiform region extends over 100 km in more than 6 hours in all squall line events observed in this study. The average cloud top temperature below -450C indicates an abundant amount of ice crystals. Radar data analysis shows that reflectivity value and surface rainfall intensity in the core part of the squall system always higher than the outer part, with maximum reflectivity value observed on the lower level of the convective cells. Analysis of the vertical structure of squall system shows that height of convective cells on the first squall system reached 17 km, while on the second squall system reached 12 km. The origin place where the squall line formed determines the structure and character of the squall system. These findings show that updraft mechanism on the continental area is generally stronger than around marine areas.
Revisiting the impact of mid-latitude cold air outbreaks on the Maritime Continent weather
Authors: Abdillah M R , Iwasaki T
Published: August 2019

The East Asian winter exhibits frequent cold air outbreaks (CAOs), or cold surges, which often cause severe cold waves in the extratropics. CAOs are also of importance for forecasters in the Maritime Continent because the associated equatorward outflows can influence tropical weather. Various CAO definitions have been documented, but a definition based on a quantitative approach was only recently proposed. Studies of the CAO impact often linked a surge index in the subtropics instead of an index in the midlatitude where CAOs basically occur. Here, we investigate the impact by using a quantitative CAO index, which is defined by integrating cold air mass flux below a threshold potential temperature over midlatitude East Asia (45°N, 90°-135°E). From a climatological analysis, tropical convections are significantly observed two-to-four days following CAO event (i.e., the peak of CAO index), indicating CAO impacts. However, case studies show that the impacts vary among independent CAO cases due to influences of associated synoptic conditions, which affect the pathways of northerlies propagation and consequently hinder or amplify the impacts. Several impact patterns and their possible causes are discussed. A better understanding of East Asian CAO variability can improve the predictability of weather over the Maritime Continent.
Analysis of the Meteorological Condition of Tropical Cyclone Cempaka and Its Effect on Heavy Rainfall in Java Island
Authors: Samrin F , Irwana I , Trismidianto  , Hasanah N
Published: August 2019

Indonesia, literally tropical cyclone free area, still gains some influence from the surrounding cyclones, such as high-intensity precipitation which causes flooding. Therefore, cyclones monitoring is important to observe its growth, movement and intensity. Using ECMWF ERA-Interim data, Himawari-8 channel infrared 1 (IR1), and GSMaP satellite data, this study attempts to spatially analyze the evolution of Cempaka tropical cyclones (occurred on November 2017), propagation cyclone and its effect to rainfall over Java Island based on the brightness temperature of the cloud. The results show that the Cempaka tropical cyclone has a three-day life span and moves from the southern ocean of Central Java to the northeast (East Java) and the peak occurs on November 27th, 2017 at 19:00 LT to 23:00 LT. Compared to rainfall data, the intensity of rainfall at 7 areas closed to Cempaka tropical cyclone began to increase ever since the cyclone peak and continue to rise despite the cyclone was slowly decaying. With this result, we hope in the future we can anticipate the impact of any tropical cyclones that arise near Indonesia.
Irradiance forecast model for PV generation based on cloudiness web service
Authors: Nguyen Dung V , Delinchant Benoit , Dinh Binh V , Nguyen Truong X
Published: August 2019

Among renewable energies that play a critically important role to achieve a sustainable development in the future, solar photovoltaic (PV) power have been growing dramatically recently. Despite the enormous potential of solar PV, its drawback, which is intermittent in generation, imposes a significant issue on electrical system, such as stability or operation planning of the system. One of the solutions for the problem is PV generation forecast that have been researched in various studies. This paper presents a methodology to obtain an indirect PV production forecast model. Processes of model formation, validation and test are performed in the study using real data from a Campbell Scientific weather station Grenoble, France.
Ag-doped Ti-RH-MCM-41 synthesis using rice husk silica and its antibacterial efficiency
Authors: Rukleng S , Chamlaiand A , Srikongka P , Areerob T
Published: August 2019

Ag-Ti-RH-MCM-41 samples were prepared via rice husk silica with in-situ (one-pot) and ex-situ (sequence) methods to improve the antibacterial property on RH-MCM-41 and Ti-RH-MCM-41. Thus, this work proposed to investigate the antibacterial property of these materials using gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) and compared with TiO2 (rutile), RH-MCM-41 and Ti-RH-MCM-41. The XRD represented MCM-41 showed the broad peak of 100 at 2 theta equal to 2.2° after adding Titanium and Silver on RH-MCM-41. The XRD spectrum represented Titanium and Silver showed the characteristic peaks of anatase TiO2 but Ag nanoparticles (AgNPs) diffraction peaks did not clearly present in Ag-Ti-RH-MCM-41 (in-situ). On the other hand, the XRD spectrum of Ag-Ti-RH-MCM-41 (ex-situ) presented the small peaks of AgNPs according to the formation of AgNPs during calcination. Antibacterial efficiency of samples was tested via inhibited zone test (clear zone). The Ag-Ti-RH-MCM-41 (in-situ) and Ag-Ti-RH-MCM-41 (ex-situ) exhibited the antibacterial against while RH-MCM-41 and Ti-RH-MCM-41 did not present the antibacterial performance. Thus, Ag-doped Ti-RH-MCM-41 can improve the antibacterial property on RH-MCM-41 and Ti-RH-MCM-41.
Modulus of elasticity assessment of glass-fibre reinforced bark-based panels by acoustic resonance vibration non-destructive test
Authors: Tsalagkas D , Börcsök Z , Pásztory Z
Published: August 2019

One of the main properties of solid materials are their stiffness. Acoustic vibration non-destructive tests have been successfully used to predict the stiffness, i.e. Young’s modulus or modulus of elasticity (MOE) values of solid wood and wood-based panels. In this work, there was an attempt to evaluate the relationship of dynamic MOE longitudinal and static MOE values, of low-density panels produced from bark particles reinforced with various length glass fibres. The findings of the results and the observed strong coefficients of determination suggest the possibility of the proposed Non-Destructive Test (NDT) method as a prediction tool for the MOE estimation of similarly produced bark-based panels. By means of this non-destructive method can be tested the materials without breaking the material and the results available right after the test.
Experience of Geographical Information Systems (GIS) application in regional planning of economic development
Authors: Devcic Anton , Sostar Marko , Andrlic Berislav
Published: August 2019

The aim of this paper is to analyze the experience of applying the geoinformation system for the purpose of quality management and sustainable development. Enterprises from all fields of activity, including maintenance, use geoinformation systems in their strategic planning. At the very beginning of the work are described the terms of geoinformation systems, their application and capabilities, and the software for making GIS is described. Through examples of good practice, an overview of the application of GIS in the fields of agriculture, transport and ecology will be presented on case study of Croatia.
1H and13C NMR investigation of oils extracted from exotic fruits
Authors: Siciliano C , Napoli A , Aiello D , De Luca P , Temperini A
Published: August 2019

Exotic fruit seeds are waste of industrial preparation of foods and human consumption. The contents in terms of nutrients of oils extracted from exotic fruit seeds are not fully understood, and they remain object of study. We propose a practical, inexpensive, qualitative and quantitative approach based on the use of1H and13C NMR spectroscopy for the fatty acid chain profiling of these oils. The composition of eleven seed oils was investigated. The amounts of linoleic (from 3.5% in Rambutan to 84.6% in Feijoa), oleic (from 6.9% to 68.7% in Papaya), and saturated fatty acid chains (from 7.9% in Feijoa to 49.5% in Rambutan) were determined. The total contents of unsaturated fatty acid (MUFA and PUFA) chains in oils ranged from 37.5% in Mangosteen to 91.5% in Feijoa. The oils were characterized by saturated/unsaturated (SFA/PUFA) ratios ranging from 0.08 to 1.07, with values which were superior to that commonly reported for extra virgin olive oil. These ratios are potentially favorable for human health. The ANOVA test showed the model to be remarkably significant (p < 0.05). Spectral data agreed those reported in the literature for conventional methods. Although linolenic acid was not detected in all oils, their fatty acid chain profiles make them desirable in terms of nutrition and as alternative energy sources.
Influence of slag powder in the cement mortar mixes on the characteristics of compactness and freeze –thaw strength
Authors: Nicula L M , Corbu O , Iliescu M
Published: August 2019

Worldwide, there is a clear imperativeness to reduce the consumption of non-renewable raw materials. The aim of the research is to obtain new ecological materials with applicability in the construction field, but also to efficiently manage these by-products by eliminating it completely and re-introducing it into the economic circuit. We envisaged the use of slag products as a material cementitious characteristics or as artificial aggregates, so that materials embedded in construction produce as little environmental impact as possible. After cooling, the blast furnace slag products was used in the new mortar mixes in two forms: in the form of a powder product milled from the granulated slag, and in the form of an aggregate made of non-granulated slag, sorted to the sized of 0/4 mm. Ground-granulated slag in the form of a powder below 63 μm was used as an addition to the cement mass, and the newly obtained artificial aggregate, sorted to 0/4 mm, was used in various percentages for replacing the natural aggregates in the control mix. The results show that the combined use of slag powder as an addition to the cement mass and artificial slag aggregates, regardless of the percentage of substitution of Natural aggregates in the mortar mortar mix, has led to the development of new mortar mixes with higher compaction than the control mortar. The higher filling rate due to the use of ground slag has influenced the increase of compressive strengths and freeze-thaw strengths from the repeated freeze-thaw action for new cement mortar mixes with blast furnace slag, as compared to the control mortar mix.
Process of magnetizing bulk amorphous alloys Fe43+xCo29-xY8B20 (x=0 or 5)
Authors: Nabialek M , Jeż B , Jeż K , Pietrusiewicz P , Bloch K , Gondro J , Abdullah M M A B , Sandu A V
Published: August 2019

The paper presents the results of investigations of the structure and magnetic properties of Fe43+xCo29-xY8B20 bulk amorphous alloys (x = 0 or 5). Alloy samples were made using injection a liquid alloy into a copper mold. The produced materials were characterized by soft magnetic properties, i.e. a high saturation of magnetisation value (about 1.15T) and a relatively low coercive field value (below 100 A/m). Increasing the cobalt content in alloys affected the high Curie temperature (around 700K). On the basis of H. Kronmüler's theory, an analysis of the magnetisation process in area so-called the approach to ferromagnetic saturation was carried out. The analysis showed that the impact on the process of magnetizing the produced materials have linear defects in the form of pseudo-dislocation dipoles.
Phases and compounds composition analyze of ZnMgCa biodegradable alloy
Authors: Popescu S (Dobriţă) , Stanciu S , Cimpoeşu R , Istrate B , Ştirbu I , Ioniţă I , Prisecariu B A
Published: August 2019

Besides biocompatible materials, a new class of metallic materials with medical applications dedicated to specific traumas is that of biodegradable materials. Zinc-based materials are mentioned as the ‘Calcium of the XXI century’. Zn has been considered as one of the newest promising biodegradable metallic metals together with Mg-based and Fe-based alloys. A new experimental composition of ZnMgCa alloy was obtained using an induction furnace from high purity zinc, magnesium and calcium materials. The material chemical compounds and phases were determined using EDS Bruker detector and XRD X’Pert equipment in molded state of the alloy. Microstructure of the alloy was determined using scanning electron microscopy and the distribution of constituents using VegaTescan software.
Obtaining and characterisation of high entropy alloys used for medical applications
Authors: Geantă V , Voiculescu I , Ştefănoiu R , Codescu M , Kelemen H , Pavel G , Vlădescu A , Sandu V A
Published: August 2019

The experimental CrFeMoNbTaTiZr alloys were designed based on the extremely low bio-toxicity of the chemical elements. They are currently used as a basis for alloying of classical alloys used in medical device manufacturing. From this alloying system, were obtained in a Vacuum Arc Remelting (VAR) equipment six alloys: CrFeMoNbTaTi, CrFeMoNbTaZr, CrFeMoTaTiZr, CrFeTaNbTiZr, CrTaNbTiZrMo and FeTaNbTiZrMo. The microstructural analysis of the obtained alloys have been performed by optical and SEM microscopy. The microhardness tests show results in the range of 575 – 1337 HV0.2 / 10. In order to improve the mechanical properties heat treatment procedures have been applied.
The active screen influence of edge effect in plasma nitriding
Authors: Perju M C , Axinte M , Nejneru C , Cimpoesu N , Ţugui C A
Published: August 2019

Plasma nitriding thermochemical treatment has a beneficial effect regarding wearing resistance. One of the disturbing effects for plasma nitriding is edge effect, which modifies the properties uniformities on the edges of the treated part. Edge effect is found in the intersection area of the two surfaces adjacent negative light. The active screen has a role in modifying the plasma field for the entire part, so also in the edges areas. This overcomes and reduces the negative technological consequences of the edge effect. Different analysis for the subjected areas were made, also on the surface parts but also in depth of the parts, in it’s section.
Performance of local fly ash geopolymers under different types of acids
Authors: Burduhos Nergis D D , Vizureanu P , Andrusca L , Achitei D C
Published: August 2019

A new class of ceramic materials, known as geopolymers, possess comparable or even higher mechanical and chemical properties than ordinary Portland cement-based materials. Because geopolymers can be used in a wide variety of areas, from civil engineering applications to decorative objects manufacturing, they can get in contact with different types of acidic corrosive substances. The degradation degree depends mostly on the acidic solution concentration and the exposure time. Due to the interaction between the geopolymer compounds, Al, Si and Fe ions solubility and the corrosive environment substance, there may follow severe consequences on the material mechanical properties. These consequences are highly related to the geopolymers three-dimensional structure degeopolymerization. The performance of geopolymers under severe environmental condition depends on the raw material, mineralogical composition and activation method. The aim of this paper is to present the effects of nitric acid, sulfuric acid and hydrochloric acid exposure on the local fly ash geopolymers compressive strength and microstructure.
In vitro corrosion behavior of Ti-Mo-W alloys in artificial saliva
Authors: Ghica Ş I , Cotruţ C M , Buzatu M , Antoniac I V , Geantă V , Buţu M , Petrescu M I , Ştefănoiu R , Ungureanu E , Iacob G , Ionescu R N
Published: August 2019

Titanium and its alloys are preferred materials used for medical devices manufacturing due to their specific properties. The corrosion behavior in artificial saliva of the newly developed Ti-Mo-W alloys, with elastic modulus closer to the human bone value was studied by means of linear polarization technique in the following steps:i)measurement/monitoring of open circuit potential (EOC) over 6 hours;ii)tracing linear polarization curves from ±200 mV (vs. OCP) - Tafel plots, with a scan rate of 0.167 mV/s. Electrochemical tests were performed according to ASTM G59-97 (2014)using a Potentiostat/Galvanostatto which a low current interface (LCI) was coupled. The tests were performedin Fusayama Meyer artificial saliva with a pH of 5.2 at the human body temperature (37±0.5°C) which mimic the oral environment. The results indicate that the alloys Ti15Mo7W and Ti15Mo11W have better corrosion behavior than Ti6Al4V.
Accumulation of stress induced martensite in Fe43.5Mn34Al15±xNi7.5∓X shape memory alloys
Authors: Apostol V , Lohan N M , Mihalache E , Comăneci R I , Cimpoesu N , Pricop B , Popa M , Bujoreanu L G
Published: August 2019

Fe43.5Mn34Al15Ni7.5 shape memory alloys (SMAs), have drawn considerable attention from the part of scientific community due to its superelastic behaviour, stable over a large thermal range (from -50 to +150°C) [1]. After cyclic heat treatment, solution treatment and ageing, the specimens became oligocrystalline and were reinforced by NiAl nanoprecipitates. The typical thermomechanical processing routine, before cyclic heat treatment of FeMnAlNi alloys, involves hot rolling, annealing and cold rolling [2]. The present paper discusses the effects of ± 1.5 at. % aluminium substitution with nickel, by correlating tensile behaviour with microstructural observations. The SMA specimens with chemical composition Fe43.5Mn34Al15±1.5Ni7.5∓1.5 were subjected to tensile tests, comprising loading-unloading cycles, based on which recoverable strain and energy storage efficiency were calculated. Considering that, in each cycle, a permanent strain was obtained, it follows that not all of the amount of stress induced martensite completely reversed to austenite, but a small part of it was accumulated in each cycle. By optical and scanning electron microscopy, the microstructural changes correlated with stress induced martensite accumulation were emphasized, while considering the effects of ± 1.5 at. % Al substitution with Ni.
A probabilistic model for predicting grain growth processes in alloys
Authors: Réti T , Felde I , Réger M , Tóth L , Fried Z
Published: August 2019

This paper deals with a possible generalization of the traditional grain growth kinetic functions. A novel probabilistic model devoted to the grain growth prediction in alloys is presented. It is based on the extension of the traditional power law kinetic equation proposed by Beck. The Beck’s isothermal kinetic equation is defined as D(t)=A*exp(-E/RT)*tm where D(t) is the grain size (diameter), t is the time, E is the activation energy, A is the preexponential factor, m is the time exponent, R is the universal gas constant and T is the absolute temperature. The novel probabilistic model proposed is based on the concept of the mixture of probability density functions. In this model it is assumed that during grain growth the activation energy (E) is not constant, but its distribution is determined by the initial grain morphology of alloys. More exactly speaking, it is supposed that the activation energy is a random variable which is characterized by the probability density function g(E) of the activation energy. By using appropriately selected probability density functions, different types of generalized grain growth kinetic equations can be established. Based on computer simulations, the application of the extended grain growth kinetic models is demonstrated by examples.
Optimization of the objective function –surface quality by end-milling dimensional machining of some aluminum alloys
Authors: Ţîţu M A , Pop A B , Ţîţu Ş , Pop G I
Published: August 2019

In the aerospace industry, the milling of aluminum alloy parts is a machining process with the primary purpose of removing high volumes of material. Aluminum alloys are materials that have relatively good machinability, which helps the process because many of the components of the aircraft are of high dimensions. These parts have many pockets more or less deep, and the removal by cutting off about 90% of the initial volume of the workpiece is a matter of consideration. The manufacturing process is protracted and involves long semi-finishing and finishing operations, so it is recommended that any researcher who begins and finishes an experimental study should do it base on a specific experimental plan. Mathematical statistics techniques and methods are used, but also optimization methods that lead to a rational choice of process parameters, process input data and objective functions that need to be improved. This scientific paper presents applied research based on an extremely pertinent active experiment that has led to some practical solutions applied in the aerospace industry worldwide. The dedicated objective function on which the study conducted in this case was the mean arithmetic deviation of the surface profile. The independent variables were chosen by the concrete application of a dispersion analysis applied to the milling process, namely the cutting speed, the cutting depth and the feed per tooth. Interpretation of the results was performed by a graphical evaluation of the normality of the data distribution, by presenting the histogram responses as well as by the dispersion diagrams. It was used for a better correlation a 3D graphical analysis that followed the Ra variation of the mean arithmetic deviation of the machined surface profile under the influence of the cutting parameters and the independent variables respectively. The obtained conclusions led to the validation of the experimental model and the application of the research presented within an aerospace industry organization with important global valences.
Treatment of industrial slag zinc ferrite by zeolitic sludge
Authors: De Luca P , Bernaudo I , Candamano S , Siciliano C , Macario A
Published: August 2019

The study reports the results in the removal efficiency of the metals released by zinc ferrite in aqueous systems, using a zeolitic sludge as an ion exchanger The so-called zinc ferrite is an industrial waste produced during the treatment of minerals for zinc extraction. The zeolitic sludge used in the experimental campaign is a by-product that derives from industrial processes and contains a combination of synthetic zeolites such as 4A (LTA) and 13X zeolite (FAU). Initially, different systems have been prepared, with predefined weight ratios of zeolitic sludge/zinc ferrite/water. The systems were analyzed, at different times, by plasma mass spectrometry (ICP-MS) that allowed to measure the variation of concentration of Fe, Mg, Ca, Zn, Mn, Pb, Na, K ions. Zeolitic sludges were efficient for the total absorption of Pb and Zn ions.
Brackish water treatment with carbon nanotubes
Authors: Foglia P , Vuono D , Siciliano C , Napoli A , Nagy J B. , De Luca P
Published: August 2019

The present work aims to experiment the action of carbon nanotubes (MWCNTs) in the removal of sodium chloride from aqueous systems, not using them as a membrane but dispersing them directly in solution, in order to evaluate possible applications in the desalination of brackish water. For this purpose, different aqueous systems have been prepared by varying the sodium chloride concentration and the amount of carbon nanotubes dispersed therein. The systems were stirred for scheduled times and then the amount of residual sodium chloride was measured by drying, after filtration, the systems and weighing the dry residue. In the final part of the experimentation, after having identified the best system, the tests were carried out directly on sea water and using different types of carbon nanotubes such as not oxidized (MWCNTs) and oxidized (MWCNTS-ox) ones.
Investigation of mode II interlaminar fracture toughness of lignocellulosic laminated specimens – an experimental and numerical approach
Authors: Baba M N , Ulea M , Roşca I C , Mihălcică M , Scutaru M L
Published: August 2019

Mode II interlaminar fracture toughness of lignocellulosic laminate composite materials made of beech veneer with urea formaldehyde resin and rye flour was investigated using the end notched flexure specimens (ENF). In order to determine the critical value of the strain energy release rate GIIc
associated with the interlaminar crack onset, the experimental data analysis was conducted by means of a mixed mode bending device in conjunction with a compliance calibration approach for data reduction. The interlaminar crack propagation under pure mode-II loading was also simulated by finite element analysis using general contact in Abaqus/Explicit, with Virtual Crack Closure Technique (VCCT) as fracture criterion. Good agreements between the load-displacement curves obtained through the use of finite element analyses and the experimental testing results were obtained.
Influence of process parameters for Selective Laser Melting on the roughness of 3D printed surfaces in Co-Cr dental alloy powder
Authors: Baciu A M , Bejinariu C , Corăbieru A , Mihalache E , Lupu–Poliac M , Baciu C , Baciu E R
Published: August 2019

Modern technologies of Additive Manufacturing type allow for the obtaining of the metal components specific to medical prosthetics in the best conditions. Selective Laser Melting (SLM) method is frequently used in dental medicine since there is an obvious trend to replace the classical casting techniques especially for non-noble Co-Cr alloys. According to the values of processing parameters (SLM) there will be parts having different roughness of the exterior surfaces. The conducted studies analysed the influences exercised by three process parameters (laser power – P, scan speed – vscan and exposure time – te) on roughness amplitude expressed by value (Ra). By combining the three distinct values adopted for each parameter we made nine sets of lamellar samples on whose non sandblasted surface, surface sandblasted once and surface sandblasted in two successive stages we carried out roughness measurements. Based on the results obtained for (Ra) parameter we formulated some recommendations for the technological parameter values that may provide surface roughness adequate to the subsequent destination of the processed parts (SLM).
Heat treatment behavior of alternator shafts steels
Authors: Ghiban B , Bran D T
Published: August 2019

The present paper analyzes properties such as the hardness, the tensile and toughness behaviour and the microstructure for multiple bars of C40 and C45 steel used for shafts in alternators. The materials have been manufactured by rolling processes, followed by normalization treatments or forging processes followed by normalization treatments. Heat treatments are performed on steels to produce different microstructural phases that affect the mechanical properties. Microstructural changes during austenite decomposition depend on the transformation temperature region and cooling rate. Over the years, many experimental studies have been performed to reveal the microstructural changes during isothermal holding or continuous cooling of austenite for various kinds of steels. The isothermal transformation (IT) diagram, which is also called the time-temperature-transformation (TTT) diagram, and the continuous cooling transformation (CCT) diagram have been developed to graphically characterize the decomposition transformation as a function of time and temperature. However, when these diagrams are based on experimental measurements, several limitations are present. Each diagram is limited because the temperatures at which specific transformations occur can vary due to several factors, such as: the chemical composition of steel, the solid solution condition in the austenite prior to cooling and transformation, the presence of precipitates in austenite, the prior austenite grain size, and the applied stresses during the transformation.
Influence of surface roughness and current intensity on the adhesion of high alloyed steel deposits - obtained by thermal spraying in electric arc
Authors: Haraga R A , Bejinariu C , Cazac A , Toma B F , Baciu C , Toma S L
Published: August 2019

In this paper the surfaces of some steel samples, low alloyed, were covered by electric arc thermal spray with a steel layer, high alloyed, containing FeNiCrSiB-WC/TiC, using a core wire. In order to study the influence of process parameters on obtained deposits, the surface roughness and the intensity of electric current varied on three levels and the rest of the technological parameters were kept constant. The microstructural characteristics, chemical composition, physical and mechanical properties of the obtained deposits were investigated by SEM analysis of microhardness and by X-ray diffraction. The deposition porosity was investigated by optical microscopy. The adhesion of the layers was investigated by the traction test. Studies have shown that by increasing the intensity of the electric current respectively the arc temperature, the deposition porosity decreases by 23,4%, the microhardness HV and the adherence of the samples subjected to the test increases. The FeNiCrSiB-WC/TiC layers, deposited on low alloyed steel support, can be considered as convenient solutions for obtaining hard, wear-resistant surfaces.
Optimization of processing parameters for graphitization of oil palm trunk waste at lower heating temperature
Authors: Karim N A , Ghazali C M R , Ramli M M , Sandu AV , Chirila E , Abdullah M M A
Published: August 2019

Previously synthetic graphite was produced at higher temperature which is around 2,500 °C in complex processing method. The method bear the name of the scientist whose discover the synthetic graphite namely “Acheson Process”. However, via pyrolysis process, in controlled heating condition, and specific heating rate by utilizing oil palm trunk waste, synthetic graphite was managed to produce at much lower heating temperature. In this research, the heating temperature were varied in the range of 500 °C, 800 °C, and 1,000 °C. The heating rate applied also varied, from 5 °/min to 10 °/min and 20 °/min. After heating treatment, the samples were characterized using X-ray Diffraction (XRD) and analysed by X’Pert Highscore Plus software. Graphitic nature of the synthetic graphite produced was further supported by RAMAN analysis. The morphological study was carried out by using Scanning Electron Microscope (SEM). Based on the analysis, optimum processing parameters was optimized. It is at the temperature of 800 °C and at the heating rate of 20 °/min.