bluuebunny/crossref_metadata_2025 huggingface dataset:
Startup steady shear flow from the Oldroyd 8-constant framework
Authors: Saengow C. , Giacomin A. J. , Grizzuti Nino , Pasquino R.
Published: June 2019

One good way to explore fluid microstructure, experimentally, is to suddenly subject the fluid to a large steady shearing deformation and to then observe the evolving stress response. If the steady shear rate is high enough, the shear stress and also the normal stress differences can overshoot, and then they can even undershoot. We call such responses nonlinear and this experiment shear stress growth. This paper is devoted to providing exact analytical solutions for interpreting measured nonlinear shear stress growth responses. Specifically, we arrive at the exact solutions for the Oldroyd 8-constant constitutive framework. We test our exact solution against the measured behaviors of two wormlike micellar solutions. At high shear rates, these solutions overshoot in stress growth without subsequent undershoot. The micellar solutions present linear behavior at low shear rates; otherwise, their behavior is nonlinear. Our framework provides slightly early underpredictions of the overshoots at high shear rates. The effect of salt concentration on the nonlinear parameters is explored.
Coexistence of high electrical conductivity and weak ferromagnetism in Cr doped Y2Ir2O7 pyrochlore iridates
Authors: Dwivedi Vinod Kumar , Mukhopadhyay Soumik
Published: June 2019

We report the structural, magnetic, and electrical transport properties of Y2Ir2−xCrxO7 pyrochlore iridates. Chemical doping leads to the order of magnitude enhancement of electrical conductivity. The introduction of Cr3+ at the Ir4+ site tends to distort the Ir–O6 octahedra and weakens antiferromagnetic correlation. The x-ray photoemission spectroscopy measurements suggest the coexistence of Ir4+ and Ir5+ valence states in the Y2Ir2−xCrxO7 compounds. The concentration of Ir5+ is enhanced with Cr doping, leading to weak ferromagnetism and enhanced electrical conductivity. A cluster-glass-like transition is also observed at low temperatures with Cr doping, possibly due to competing ferromagnetic and antiferromagnetic interaction.
Interdendritic microsegregation development of high-strength low-alloy steels during continuous casting process
Authors: Zhang Dayue , Strangwood Martin
Published: June 2019

A 1-D model based on DICTRA software was used to simulate Mn microsegregation in high-strength low-alloy steels during continuous casting. The experimentally determined (using a cumulative profiling method) segregation results were in good agreement with the modelling results. Steels undergoing solidification via a peritectic reaction had a larger segregation range than non-peritectic steels ascribed to trapping of the alloying atoms in liquid by austenite acting as a diffusion barrier. Subsequent, post-solidification cooling through the single phase austenite field decreased the microsegregation level, although the last γ→ α phase transformation did affect the segregation profile in the solute-depleted dendrite centre. Simulation indicates that segregation levels could be reduced by decreasing either secondary dendrite arm spacing or adopting faster cooling rates through solidification.
Thorium distribution on the Moon: new insights from Chang’E-2 gamma-ray spectrometer*
Authors: Zhu Meng-Hua , Chang Jin , Ma Tao
Published: June 2019

We present the thorium distribution on the lunar surface derived from observations by theChang’E-2gamma-ray spectrometer (CE-2GRS). This new map shows a similar thorium distribution to previous observations. In combination with this new thorium map and impact cratering model, we investigate the origination of thorium on the Moon’s highlands, which was previously thought to be contributed from Imbrium ejecta. We found that the Imbrium ejecta has a small contribution (∼20%–30%) to the thorium on the lunar highlands but most thorium is likely to be indigenous before the deposition of the Imbrium ejecta. This new thorium map also confirms that the eastern highlands have a relatively higher thorium concentration than the western highlands. We propose that the thin crust and large basins on the eastern highlands are responsible for this difference in thorium.
Strange quark star in dilaton gravity
Authors: Peivand Alireza , Naficy Kazem , Bordbar Gholam Hossein
Published: June 2019

In this work, we first obtain the hydrostatic equilibrium equation in dilaton gravity. Then, we examine some of the structural characteristics of a strange quark star in dilaton gravity in the context of Einstein gravity. We show that the variations of dilaton parameter do not affect the maximum mass, but variations in the cosmological constant lead to changes in the structural characteristics of the quark star. We investigate the stability of strange quark stars by applying the MIT bag model with dilaton gravity. We also provide limiting values for the dilaton field parameter and cosmological constant. We also study the effects of dilaton gravity on the other properties of a quark star such as the mean density and gravitational redshift. We conclude that the last reported value for the cosmological constant does not affect the maximum mass of a strange quark star.
Properties of filaments in solar cycle 20-23 from McIntosh Archive
Authors: Mazumder Rakesh
Published: June 2019

A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection (CME), which has an adverse effect on space weather. Hence, research on filaments has attracted much attention in the recent past. The tilt angle of active region (AR) magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines (PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.
The morphology, kinematics and metallicity of blue-core galaxies
Authors: Chen Yong-Yun , Chen Yan-Mei , Gu Qiu-Sheng , Shi Yong , Bing Long-Ji , Yu Xiao-Ling
Published: June 2019

We select 107 blue-core galaxies from the MaNGA survey, studying their morphology, kinematics as well as the gas-phase metallicity. Our results are as follows: (i) In our sample, 26% of blue-core galaxies have decoupled gas-star kinematics, indicating external gas accretion; 15% have bar-like structure and 8% show post-merger features, such as tidal tails and irregular gas/star velocity field. All these processes/features, such as accreting external misaligned gas, interaction and bar, can trigger gas inflow. Thus the central star-forming activities lead to bluer colors in their centers (blue-core galaxies). (ii) By comparing with the SDSS DR7 star-forming galaxy sample, we find that the blue-core galaxies have higher central gas-phase metallicity than what is predicted by the local mass-metallicity relation. We explore the origin of the higher metallicity, finding that not only the blue-core galaxies, but also the flat-gradient and red-core galaxies all have higher metallicity. This can be explained by the combined effect of redshift and galaxy color.
Insight-HXMT observations of the Crab pulsar
Authors: Tuo You-Li , Ge Ming-Yu , Song Li-Ming , Yan Lin-Li , Bu Qing-Cui , Qu Jin-Lu
Published: June 2019

We report on X-ray emission properties of the Crab pulsar (PSR B0531+21) using observations by insight-HXMT during its first year after launch. We obtained high signal-to-noise profiles in the X-ray energy band 11–250 keV. We have confirmed an increase in the flux ratio of the second peak over the main peak with increasing energy, consistent with other missions. The separation of the two peaks shows no significant trend with increasing energy. The phase-averaged spectrum, fitted by a logpar model, and the phase-resolved spectra of the Crab pulsar, fitted by a powerlaw in the different energy bands of HXMT, are consistent with RXTE and NuSTAR in that photon indices evolve as a function of phase as well as a function of energy, contributing to a broadband modeling.
A catalog of DB white dwarfs from the LAMOST DR5 and construction of templates
Authors: Kong Xiao , Luo A-Li , Li Xiang-Ru
Published: June 2019

In this study, we employ machine learning to build a catalog of DB white dwarfs (DBWDs) from the LAMOST Data Release (DR) 5. Using known DBs from SDSS DR14, we selected samples of high-quality DB spectra from the LAMOST database and applied them to train the machine learning process. Following the recognition procedure, we chose 351 DB spectra of 287 objects, 53 of which were new identifications. We then utilized all the DBWD spectra from both SDSS DR14 and LAMOST DR5 to construct DB templates for LAMOST 1D pipeline reductions. Finally, by applying DB parameter models provided by D. Koester and the distance from Gaia DR2, we calculated the effective temperatures, surface gravities and distributions of the 3D locations and velocities of all DBWDs.
Evaluating a proxy of the local entropy production rate on the solar photosphere
Authors: Viavattene G , Berrilli F , Consolini G , Del Moro D , Giannattasio F , Giovannelli L , Penza V
Published: June 2019

The evaluation of the entropy production rate on the solar photosphere and its probability distribution are the key issues for studying the non-equilibrium dynamics of the solar convection. The local entropy production rate can be easily evaluated using the vertical heat flux as a proxy, which is given by a product between the line-of-sight velocity and the surface temperature. In this framework, the solar photosphere provides an incomparable laboratory to study turbulent convection in a dissipative non-equilibrium system near a steady state. In this work, we present some preliminary results on statistics of the local entropy production rate via the vertical heat flux, using line-of-sight velocity and temperature maps of the solar photosphere which are extracted from spectro-polarimetric data making use of the Center of Gravity Method and the simple black body radiation law.
Influence of thermal conductivity and of non-constant relaxation time on thermoelectricity in Mg3Sb2
Authors: Farris R , Maccioni M B , Filippetti A , Fiorentini V
Published: June 2019

We discuss the effects of different approximations to thermal conductivity and relaxation time on the thermoelectric figure of merit ZT in n-doped Mg3Sb2. We use density-functional electronic structure and Bloch-Boltzmann transport theory with an energy-dependent relaxation time. ZT is monotonically increasing with T in our range (300-700 K) with a maximum value of ∼1.5.
The build up of a test station facility for the SIS100 superconducting modules
Authors: Gambardella U , Iannone G , Saggese A
Published: June 2019

More than eighty quadrupole modules, especially designed and fabricated at JNIR in Dubna, will be used at the FAIR facility in Darmstadt. Prior the installation in the new accelerator SIS 100 tunnel, the modules need to be tested by an independent laboratory. The required test have to be the same for all the modules and the answer will be the benchmark for the final decision on accepting or rejecting the module. With this target in mind, a system with as much as possible automatisms will be realized. Three kinds of tests will be performed: mechanical, thermal and electrical. The mechanical test will concern on the search of vacuum leaks, if present, and on the measurement of the limit pressure reached in the vessel. The thermal test will have to check that the various thermometer, scattered inside the modules, will be correctly working and that the heaters are able to deliver the generated heat. The electrical tests will verify the insulation to ground of both the devices and the superconducting coils and bus-bars. All tests will be done in a thermal sequence: at room temperature, at the cryogenic working temperature of 4.5 K, and finally at room temperature again.
Thermal compensation system in advanced and third generation gravitational wave interferometric detectors
Authors: Aiello L , Cesarini E , Fafone V , Lorenzini M , Minenkov Y , Nardecchia I , Rocchi A , Sequino V
Published: June 2019

On September 14
th
2015 the first gravitational wave signal has been detected by the Advanced LIGO interferometers, opening the era of the gravitational astronomy and giving new opportunities to investigate the universe. The Advanced LIGO and Advanced Virgo interferometers are now back in a commissioning phase in order to improve their sensitivity for the next observing run, which will start in the first months of 2019.

In the high-frequencies region of their sensitivity band, the detectors are shot-noise limited: the sensitivity in this frequency window could be improved increasing the laser input power, but this increases also the optical aberrations due to the thermal effects. The optical power absorptions in the substrate and coatings of the optics induce both an increase of the optical path length in the substrates of the mirrors (thermal lensing) and a thermal expansion of the optic itself along the optical axis (thermo-elastic deformation). Both these aberrations reduce the sensitivity of the detector, limiting its performances. In order to face and minimize them, an adaptive Thermal Compensation System is required in order to guarantee the proper operation of the interferometer.

An overview of the present Thermal Compensation System system installed on Advanced Virgo, with also a focus on the possible improvements of the actual actuators for the next generation of detectors, is presented here.
LIDAL (Light Ion Detector for ALTEA): a compact Time-Of-Flight detector for radiation risk assessment in space
Authors: Rizzo A , Berucci C , De Donato C , Di Fino L , Lamastra F R , La Tessa C , Masciantonio G , Messi R , Morone C , Picozza P , Rovituso M , Tommasino F , Narici L
Published: June 2019

Manned space missions towards Moon and Mars planned in the next decades require a reliable radiation risk assessment considering the long time exposure of astronauts (up to years) to different radiation fields. The radiation environment inside a human space habitat, generated by the interaction of the Galactic Cosmic Rays and occasionally of Solar Particle Events with the spacecraft hull, is peculiar due to its composition (ions from Hydrogen to Iron, knock out neutrons) and the large kinetic energy range of the particles. For this reason the risk assessment approach used for astronauts in space is quite different from the one used on Earth. In this approach the risk for astronauts is evaluated calculating factors which score the risk in function of physical characteristics of the single particle, like the quality factor Q (related to the radiation ionizing power) or the squared ratio between the charge (Z) and velocity (β) of the particle (Z
2/β
2).

LIDAL-ALTEA (Light Ion Detector for ALTEA - Anomalous Long Term Effects on Astronauts) is an experimental apparatus which will allow to evaluate for the first time in the field the Z
2/β
2 risk factor of the single detected particle on-board the International Space Station.

The LIDAL system is a Time-Of-Flight detector designed to work paired to three Silicon Detector Units of the ALTEA, which will measure the deposited energy of the passing particle. The velocity of the particle (β), calculated from the Time-Of-Flight measurement performed by LIDAL, allows to evaluate the particle electric charge once related to the deposited energy measured by ALTEA. A first LIDAL prototype has been developed by the University of Rome “Tor Vergata” and tested at TIFPA (Trento Insistute for Fundamental Physics Applications) proton beam line, in order to evaluate the timing performances of the detector. Results are briefly presented and the current status of the apparatus production is discussed in view of the launch scheduled for 2019.
Mathematical and geophysical methods for searching anomalies of the Radon signal related to earthquakes
Authors: Ambrosino F , De Cesare W , Roca V , Sabbarese C
Published: June 2019

A detailed analysis of a time-series of the Radon (222Rn) specific activity is carried out to identify anomalies that can be correlated with earthquakes occurrence in the monitored area. New hybrid methods are developed for this purpose and the advantages of each single component method are exploited. These methods are applied to two-years data series recorded continuously in the soils of a site within the seismo-volcanic area of Phlegrean Fields (Naples-Italy). Since the measurement system distinguishes and separately measures the 222Rn and 220Rn, an alternative estimation of the remote fraction of the gas and its anomalies has been also performed using the 220Rn trend. The results of different methods are compared to recognize and to highlight Radon anomalies. Clear relationships have been found between anomalies and earthquakes of local origin and selected according to a specific formula of the earthquake preparation zone. The effectiveness of the methods and the goodness of the results are established by the high values of the cross correlation factors between the anomalies and the occurrence of the earthquakes.
Inverse β-decay: a twin-model with boson fields
Authors: Blasone M , Lambiase G , Luciano G G , Petruzziello L
Published: June 2019

In line with a series of previous works, in this paper we discuss the inverse β-decay of accelerated protons p → n + e
+ + νe
. To make the calculation of the transition rate easier to handle, we focus on an ideal “twin-process”, assuming the counterparts of lepton fields to be scalars. The rate of p → n conversions is evaluated in both the laboratory and comoving frames, showing that the two results perfectly agree due to the Unruh effect. In spite of the minimal setting, we stress that this model is an attempt to wash technical difficulties out of the analysis of the inverse β-decay. The future goal is to investigate the concerns recently raised in literature about the compatibility of the two rates when neutrino mixing is taken into account.
Assessing future climate change impacts in the EU and the USA: insights and lessons from two continental-scale projects*
Authors: Ciscar Juan-Carlos , Rising James , Kopp Robert E , Feyen Luc
Published: June 2019

Climate change will impact many economic sectors and aspects of natural and human wellbeing. Quantifying these impacts as they vary across regions, sectors, time, and social and climatological scenarios supports detailed planning, policy, and risk management. This article summarises and compares recent climate impact assessments in Europe (the JRC PESETA III project) and the USA (the American Climate Prospectus project). Both implement a multi-sector perspective combining high resolution climate data with sectoral impact and economic models. The assessments differ in their coverage of sectors and scenarios, mix of empirical and process-based methods, handling of uncertainty, and representation of damages. Despite the dissimilarities, projected relative economic impacts are comparable, with human mortality as the dominant impact category. Both studies further show a large spatial heterogeneity of impacts that may amplify pre-existing economic inequality in the EU and US, and that mitigation can considerably reduce economic impacts. The comparison highlights the various decision-points involved in interdisciplinary climate impact modelling and lessons learnt in both projects, on the basis of which we provide recommendations for further research.
Five hundred years of anthropogenic mercury: spatial and temporal release profiles*
Authors: Streets David G , Horowitz Hannah M , Lu Zifeng , Levin Leonard , Thackray Colin P , Sunderland Elsie M
Published: June 2019

When released to the biosphere, mercury (Hg) is very mobile and can take millennia to be returned to a secure, long-term repository. Understanding where and when Hg was released as a result of human activities allows better quantification of present-day reemissions and future trajectories of environmental concentrations. In this work, we estimate the time-varying releases of Hg in seven world regions over the 500 year period, 1510–2010. By our estimation, this comprises 95% of all-time anthropogenic releases. Globally, 1.47 Tg of Hg were released in this period, 23% directly to the atmosphere and 77% to land and water bodies. Cumulative releases have been largest in Europe (427 Gg) and North America (413 Gg). In some world regions (Africa/Middle East and Oceania), almost all (>99%) of the Hg is relatively recent (emitted since 1850), whereas in South America it is mostly of older vintage (63% emitted before 1850). Asia was the greatest-emitting region in 2010, while releases in Europe and North America have declined since the 1970s, as recognition of the risks posed by Hg have led to its phase-out in commercial usage. The continued use of Hg in artisanal and small-scale gold mining means that the Africa/Middle East region is now a major contributor. We estimate that 72% of cumulative Hg emissions to air has been in the form of elemental mercury (Hg0), which has a long lifetime in the atmosphere and can therefore be transported long distances. Our results show that 83% of the total Hg has been released to local water bodies, onto land, or quickly deposited from the air in divalent (HgII) form. Regionally, this value ranges from 77% in Africa/Middle East and Oceania to 89% in South America. Results from global biogeochemical modeling indicate improved agreement of the refined emission estimates in this study with archival records of Hg accumulation in estuarine and deep ocean sediment.
Multivariate time series classification analysis: State-of-the-art and future challenges
Authors: Handhika T , Murni  , Lestari D P , Sari I
Published: June 2019

In the era of big data and internet of things (IoT) revolution, it is possible to observe some variables for an object in real time, e.g. sensor data obtained from one or more sensor devices. In addition to extrapolate these data simultaneously, the other hot issue is how to use these data for classifying some variables into some groups, respectively. Multivariate time series classification (MTSC) analysis provides various models to represent this problem according to its characteristics. In this paper, we tried to summarize state-of-the-art methods for MTSC analysis complete with their strengths and weaknesses. Furthermore, we also focused on some limitations from previous research for developing MTSC analysis in the future.
Prediction of corrosion rate in SA 283 material affected by differences soil type in controlled environments.
Authors: Putra Reza , Muhammad  , Huzni Syifaul , Fonna Syarizal
Published: June 2019

Research has been done on corrosion rates growth in SA 283 material which is influenced by differences in soil types in controlled environments. A283 grade D materials which are carbon steel formed into pipes with a diameter of 30" which is used to distribute raw water for industrial needs. Weight loss methods that are in accordance with the ASTM G 162 standard have been used in this study. The buried time of the test specimen is 720 hours as one of the variables in calculating the value of the corrosion rate that occurs. The study was conducted at the Laboratory by controlling the soil structure, reducing potential, moisture level, soil pH level so that it did not change. The results of the study on soil types with a potential redox value of 60.6 mV with a pH level of 5.67 showed the greatest corrosion rate in material A283 that is 19.67 MPY or equal to 0.499 mm/yr. The results of this study concluded that the type of soil and its environment greatly affect the corrosion rate of carbon steel, so special attention is needed in protecting the pipe from corrosion attack.
The Investigation of Mechanical Behaviour of OPEFB Fibre Reinforced Foam Material Concrete to High Speed Impact Loads
Authors: Fitriadi Nuzuli , Syam Bustami
Published: June 2019

The development of the palm oil industry today is increasing rapidly. The result of the palm oil industry is often a waste of Oil Palm Empty Fruit Bunches (OPEFB). OPEFB can be processed into fibres that can ultimately be used as an engineering material. Concrete foam is one kind of lightweight concrete that uses foam as light aggregate. Concrete foam is made by stirring a mixture of cement, sand and water and the foam that has been created by using a foam generator to create the foam separately. Once the foam is formed and then incorporated into the concrete mixture into the mould. OPEFB fibres are used as reinforcement of lightweight concrete that participated in the mixed grout. The purpose of this study is to obtain the maximum tensile stress in the concrete foam to high-speed impact. The mechanical strength of the material is to impact loads obtained by 2 gage testing method by using an air gun compressor machine. High-speed impact the test results obtained by the average tensile stress is 4.54MPa at a distance of 50mm impact and pressure 0.3MPa. This indicates that the concrete foam reinforced OPEFB fibres is more effective to absorb the impact loads lighter than the brick found in the market.
Experimental Review on Influence of Inlet Disturbance Body (IDB) at 30° Against Inhibitory Force Reduction on Three Circular Cylinders with Composed of Stagger (Variation L/D(constant=2), T/D = 1.5, 2, 3 & 4)
Authors: Cut B , Akram R , Iskandar  , Rahman A , Zulfri M , Nazaruddin
Published: June 2019

Research on the characteristics of the fluid flow across the bluff body has been carried out and placed in a variety / setting, let alone research on fluid flow across three circular cylinder arranged stagger by placing 2 (two) Inlet Disturbance Body (IDE) as a bully in front. This effort is usually done to reduce the normal force, shear force, and drag force that occurs in the bluff body of the three circular cylinders. This research was conducted experimentally in mechanics laboratories and fluid machines using subsonic wind tunnels and tested at Re = 2.2x104 based on the diameter of a circular cylinder. Variations used are longitudinal distance ratio (L/D) = 2 with a circular cylinder diameter (D = 25 mm) and transverse distance ratio (T/D) = 1.5, 2, 3 and 4 and IDE placement on the upper and lower sides from cylinder 1 (upstream) in the form of a cylinder with a diameter (d = 4mm) at 30 °. The results showed that the use of IDB at position 30° can reduce the drag force that occurs in cylinder 1 (upstream) 36 to 53% compared to with no IDE, while for cylinder 2 (upstream), the drag is higher for (T/D) = 1.5, 2 and 3 are 3.2 to 22% and at (T/D) = 4 the drag force is reduced to 9% again. About cylinder 3 (downstream - down) in the stagger configuration with IDB 30°, the drag is 4.8 to 44% higher for all distance variations (T/D) compared to the stagger configuration with no IDE. Variation in distance (T/D) also greatly affects the distribution of pressure coefficients that occur with the three circular cylinders with a stagger arrangement, causing a difference in the distribution of the drag pressure coefficient (Cdp
) and also the velocity profile behind the 3 circular cylinders with the stagger arrangement.
Failure analysis of boiler leakage due to caustic corrosion on Cr-Mo steel
Authors: Awwaluddin Muhammad , Hastuty Sri , Riyandwita Byan Wahyu , Zacharias Petrus , Siswanto Edy
Published: June 2019

In the system of steam generation, condenser and boiler are the most prone to suffer corrosion attack. It usually occurs due to the interaction between the pipe surface that made from steel with the fluid of boiler. One of the dangerous types of failure is pitting corrosion. There are several causes of pitting corrosion, such as; the oxygen content in the fluid, the amount of contaminants that may easily form a deposit on the Cr-Mo steel surface, and the use of improper concentration of inhibitors. The electrochemical process takes place during the occurrence of pitting corrosion. Failure analysis of the boiler water-wall tube is presented in this work. In order to examine the causes of failure, various techniques including visual inspection, optical microscopy, and energy dispersive spectroscopy were carried out. Tube wall thickness measurements were performed on the failed tube. The water-facing side of the tube was observed to have experienced significantly localized wall thinning. The failure mechanism is suggested as oxidation due to caustic corrosion as a result of inappropriate usage of phosphate inhibitors.
Experimental Study of Heat-Absorbent Foam Concrete Wall Based Macro-Encapsulation of Beef Tallow/Damar Gum in Building
Authors: Ismida Y , Amin M , Hamdani  , Amna U , Fazri  , Akbar C
Published: June 2019

Generally, the foam concrete that designs as the current building wall is without considering the heat absorbent. Therefore, it is necessary to find additional materials that able to absorb the heat energy. One of them is Phase Change Material (PCM). Beef tallow is an organic material of PCM that has a high heat storage capability. Commonly, an aggregate requires in the manufacture of foam concrete as reinforcement materials. This aggregate can be changed with macro-encapsulation of PCM. This study aimed to find the ability of foam concrete based macro-encapsulation of beef tallow/damar gum in absorb heat energy that will be applied in building walls. This research was conducted experimentally with the primary materials of cement, fine sand, water, foam agent, catalyst, sika, and macro-encapsulation of beef tallow/damar gum. This foam concrete wall was made with the dimension of 80 x 80 x 10 cm and varied with a mixture of beef tallow / damar gum of 0%, 1%, 3%, and 5%, respectively. The wall concrete heater was simulated with using four lamps with the power of 200 watts. The type-K thermocouple was placed on samples at 2 points, inside and on the surface, which connected with Agilent 34970A. The results showed that the effect of adding PCM resulted in a decreasing of the temperature inside and on the surface of foam concrete walls. The amount of temperature decreases due to the addition of 5% PCM is from 51.9 °C to 44.7 °C or decreased by 13.87% inside of foam concrete walls and 75.64 °C to 51.9 °C or down to 21.87% on the surface of foam concrete walls. Overall, this foam concrete based macro-encapsulation of beef tallow/damar gum is better to use as heat-absorbent in building wall application compare with foam concrete wall without using macro-encapsulation of beef tallow/damar gum.
Synthesis and Characterization Thermal of Polyurethane/MMT from Castor Oil Polyols for Coating
Authors: Zaimahwati  , Yuniati  , Jalal R , Rihayat T , Zhafiri S
Published: June 2019

The purpose of this research overall is the manufacture of polyurethane nanocomposite from castor oil with the addition of montmorillonite nanoparticles as coating material. This study consists of several stages, the manufacture of montmorillonite nanoparticles (MMT), the process of forming polyols from castor oil by epoxidation and hydroxylation reactions with catalysts. The manufacture of polyurethanes (PU) by reacting polyols from castor oil and organic montmorillonite nanoparticles was then characterized and applied to polyurethane nanocomposites as coating materials. Organic montmorillonite nanoparticles are made by an intercalation process with cetyl trimetyl ammonium bromide (CTAB). Polyurethane nanocomposite was prepared by adding organic montmorillonite nanoparticles in polyols before being mixed with toluene diisocyanate. The effectiveness of polyurethane nanocomposites as heat-resistant coatings was determined by thermal properties with thermo gravimetric analysis (TGA) equipment, then the adhesive strength was tested and the morphological properties of the material coating. The manufacture of polyurethane nanocomposite from castor oil as a film coating is applied to material and characterization.
Analysis of the Overall Equipment Effectiveness (OEE) to Minimize Six Big Losses of Pulp Machine: A Case Study in Pulp and Paper Industries
Authors: Sayuti M , Juliananda  , Syarifuddin  , Fatimah
Published: June 2019

Overall Equipment Effectiveness (OEE) is a method of measuring the usage effectiveness of the equipment. This method is known as an application of a Total Productive Maintenance (TPM) program. The ability to clearly identify the source of problem and it causal factors is the main advantage of this method since the improvement effort becomes focused. Pulp and Paper Industries is one of the manufacturing companies that produce dissolving pulp products (rayon fibre). Based on data from the fibre line department, for the period of January - July 2016, the production process of rayon fibre often experienced constraints due to the high downtime and losses in the pulp machine. This is caused of using production process equipment that had not operate optimally. It is important to find out the source of the problem and its causal factors before the company makes any improvement effort. This study aims to identify equipment losses and measure the achievement of OEE values in the pulp machine. The measurement result shows that the average of the effectiveness of pulp machine for the period of January - July 2016 was 74.01% and based on Japan Institute of Plant Maintenance (JIPM) the value has not reached the standard that is > 85%, however, there is still possibility for improvement. One of the loss factors that give the most significant effect on the overall equipment effectiveness of the pulp machine is the reducing speed, where it comprises 27.6% of the loss. One way to minimize the loss is by maintaining the actual speed of operation and maintaining wear on each pulp machine roll.
The analysis of groundwater quality around a material (solid waste) recovery facility (a case study of the Merdeka 2 material recovery facility in Depok, West Java)
Authors: Adriansyah H S , Hartono D M , Suwartha N , Gusniani I
Published: June 2019

Merdeka 2 Material Recovery Facility (MRF) is an organic waste management facility located in West Java. MRF also produces leachate water which came from organic waste that could potentially pollute shallow groundwater around the facility. Purpose of this study is to obtain knowledge regarding amount of MRF’s waste intake and composition, composition of leachate water that came from the waste, and the groundwater quality around MRF with parameters including pH, temperature, BOD, COD, Nitrite, Nitrate, Ammonia, KMnO4, Iron (Fe), and Fecal Coliform. Quality of the groundwater was analysed by knowing pollution rate based on pollution index and its association with distance variation from MRF. Results showed that amount waste that came to the facility is 0.954 ton/day with an average of waste volume 1449.20 l/day and consists of 93.4% organic waste and 6.4% non-organic waste. For MRF’s leachate water quality showed that pH, temperature, BOD and COD parameters exceeded over required standard. Shallow groundwater around MRF showed that average rate of pH, BOD, COD, Nitrate parameters is still above required standard and other parameters average is still in required standard and there is no significant correlation between distance variation with the groundwater. It can be concluded that the pollution index of the local’s shallow groundwater fall into low to mid polluted category.
Comparison Between Surfactant and Chitosan Organo-kaolin Adsorbents to Remove Metal and Organic Compound in Peat Water
Authors: Syafruddin  , Putra A , Hidayat M S
Published: June 2019

This study compares adsorbents to remove metal and organic compounds in peat water solution. The kaolin adsorbent was modified with organic compounds (organo-kaolin). Modifications used two types of organic compound namely surfactant and chitosan with the organic compound concentration used of 15%, 39% and 45% respectively from the total weight of 200 grams adsorbent. The contact time used was 30 minutes with stirring speed of 90 rpm. The concentration of metal ion Fe and organic compound was analyzed by Atomic Absorption Spectrometer (AAS) (Shimadzu UV-1800) and Total Organic Carbon (TOC), the determination of the characteristics for wavelengths before and after treatment used Spectrophotometer Fourier Transform Infra-Red (FTIR) IR Prestige-2, while organo-kaolin surface morphology used SEM. The results of the study show that organo-kaolin surfactant and chitosan successfully reduces Fe metal ion in water up to 91.8% and 88.2% of the initial concentration of 2.07 mg/L from peat water. Both organo-kaolin modification (surfactant and chitosan) ability to remove organic compound was 46.7% and 35.7%. The results of FTIR spectra testing and SEM test also show differences before and after the absorption of the metal ion Fe and organic compounds.
The Study of Gum Arabic as Surfactant on the Stability of Water-based Alumina Nanoparticle Suspensions
Authors: Nurdin Irwan , Zulkifli  , Satriananda  , Nurlaili
Published: June 2019

The stability study of alumina nanoparticle suspensions has been investigated by using gum arabic as a surfactant. The effect of particle volume fraction of alumina nanoparticle and gum arabic concentration were observed. The stability of the suspension was characterized using zeta potential and particle size distribution analysis. Several volume fractions of alumina and gum arabic concentration were dispersed in water as a solvent for suspension stability. The result showed that the stability of water-based alumina nanoparticle suspensions was increase with the decreasing of particle volume fraction and increasing of gum arabic concentration. The particle size distribution was narrow with decreasing particle volume fraction and increasing gum arabic concentration. The hydrodynamic diameter of the particles was smaller with the increasing of gum arabic concentration. The smallest particle size recorded was 164.6 nm at 0.5% gum arabic concentration. Zeta potential values were increased with the increasing of gum arabic concentration. The highest zeta potential was recorded at -36.0 mV. It can be concluded that gum arabic can be used for stabilization of water-based alumina nanoparticle suspensions.
Minimizing Embankment Slope of Rear Parts to Overcome Leakage
Authors: Gani Fauzi A. , Kurniati
Published: June 2019

The surrounding area of the river Kr. Pandrah is an area that every five years’ experience flooding. The biggest flood in 2006 has been classified as natural disasters and has destroyed public property around the area Pandrah. For that, we need a study to get an alternative to overcome. Based on the survey data and information from multiple sources and analysis of the existing condition in 2006 that the highest flood ± 0.60 m, using the HAC-RAS program obtained the largest discharge of 350 m3 / sec. River cross-section is modified into a compound with a wide cross-section of the river is still based on the existing width. The width of the left and right banks of 5 meters from the riverbank and the embankment crest width of 3 meters with a slope of 1: 1 Testing the stability of the embankment is done by using the program Geo-Slope method Bishop Grid and Radius way obtained a safety factor during the development of downstream 2.146, 2.143 upstream development, steady seepage 1.667 downstream, upstream of the steady seepage 1.183, 1.597 rapid drow down upstream and downstream rapid drow down 1,682, all the figures were below the standard security numbers. But after the biggest flood in 2016, the high embankment and duration of inundation occur above the initial predictions, so there is some point leak embankment. For further improvement can be made by reducing the slope angle of the back or make drainage embankment.
Performance of MIMO and Relay Communication System using TGn and HH Channel
Authors: Hanafi  , Hendrantoro G.
Published: June 2019

The research on relay communication systems and MIMO has been done by researchers. Both systems have advantages in increasing the system performance and capacity. While the OFDM transmission technique has the advantage to avoid ISI from receiving signals. Systems are simulated to obtain BER as a system performance parameter and determine the increase in BER due to the use of a relay and 2 antennas in communication systems. Systems are compared between relay system with the non-relay system, where both systems are simulated too for using 2 antennas and 1 antenna. Messages are sent using the OFDM technique over TGn and the HH channel. Systems with 2 antennas use the Alamouti scheme. Received messages are combined using MRC, and the original messages are detected using an ML detector at the receiver. The increase in BER obtained between relay systems compared to non-relays is 1.69 and 2.02 times when using 1 and 2 antennas on Eb/No = 9 dB. Increased BER also occurs between 2 antenna systems compared to system 1 antenna, which is 79.71 times in non-relay systems and 94.93 times in relay system on Eb/No = 9 dB. From these results, it can be seen that there is an increase in BER in the use of a relay and 2 antennas in the system. The BER system that occurs, both using the TGn channel and the HH channel, shows relatively the same results.
Genetic Algorithm as a Solutions Optimization of Tilt Angles for Monthly Periods of Photovoltaic Installation
Authors: Yassir A
Published: June 2019

Changes in the sun’s declination angle, every month for one year affect the energy received by a photovoltaic (PV). Changing the tilt angle, every month to follow changes in sun declination needs to be done so that the energy produced by PV is more optimum. Genetic algorithm (GA) was proposed in this study as the optimal PV slope solution every month of the year. GA calculates the slope angle of PV by calculating changes in sun declination, the movement of the sun from east to west, the coordinates of the location of PV installation, direct radiation and diffuse radiation. GA initializes tilt angle PV with the specified limit, then calculates to get the optimum total energy value on the inclined plane that PV can accept with the crossover, mutation and selection process. Algorithms are limited to 50 generations. The results showed that the optimization of the monthly period slope was better than the annual period. Installation with a slope angle after the monthly period optimization has increased the energy received by solar panels by 12 kWh/m2-year compared to installations with the slope of the annual period of optimization.
Papain Enzyme and Lemon as Coagulants in Cottage Cheese
Authors: Fachraniah  , Rihayat Teuku , Zaini Halim , Nita Desi , Fazil Muhammad
Published: June 2019

Cottage cheese is one type of cheese that is processed without ripening, which is made from milk coagulated using lactic acid bacteria or rennet enzyme. Another alternative as a substitute for rennet is the papain enzyme and lemon juice. This study aimed to access the influence of enzymes concentration and pasteurization temperature to the yield and quality of cottage cheese while lemon juice as fixed variable . Papain enzymes are isolated from immature papaya fruit sap, mixed with sulfite, the emulsion of gum is dried using vacum oven to become crude papain, and lemon juice obtained from ripe lemon fruit. Cottage cheese made by pasteurization of fresh cow milk, addition papain enzyme and lemon juice, stirring, and the curd is separated. Analysis products are included the percentage of curd, lactic acid, protein content, water content and texture. The best results showed that from 200 ml of fresh cow milk obtained at 0.5% enzymes and 50°C with a weight of curd 30.16%, lactic acid 0,16%, dissolved protein concentrations 375.61 mg/l, and 5.33 g in texture.
A Prospective of Coal Fly Ash Conversion to Mfi Membrane for High Grade Biofuels Purification
Authors: Jufriadi  , Saputra Hens
Published: June 2019

MFI is a structure of aluminosilicate zeolite mineral belonging to the pentasil family of zeolites. The current paper focuses on preparation of MFI zeolite from coal fly ash by hydrothermal process. Coal fly ash was utilized as the sources of silica. The as-synthesized zeolite was characterized by X-ray diffraction (XRD) to identify the structure and microstructure morphology observation by Scanning Electron Microscope (SEM) and adsorption-desorption analysis using nitrogen at 77 K. This kind of zeolite has a highly prospective to increase the purity of ethanol from technical grade become the fuel grade, catalyst, molecular sieve and adsorbent to reduce the emission gas.
The Biomass-based Desalinator Performance in a Vacuum System
Authors: Munawar  , Majuar E
Published: June 2019

The biomass-based desalination system has several problems in its application, including wasteful energy consumption in feed water evaporation systems. If weaknesses can be corrected, this desalination system is predicted to have promising applicability prospects. This study aims to develop a renewable energy based desalinator focused on modification of the evaporation system, biomass preparation, and also a study of desalinator performance. The study was carried out in a batch and continuous manner, where brackish water was fed to the desalinator, by varying the quantity of feed water, cooling water rate, and system pressure. As a response variable, it is determined that fuel needs, clean water production capacity, and the quality of water products produced the results showed that the water production capacity was influenced by cooling water flow rate, feed volume, feed discharge, and system pressure. In general, the fact is that the rate of condensate production increases with the increase in the variable. The use of a vacuum system is proven to be able to improve system performance, where the condensate production capacity can be increased from 4.165 ml/minute in the atmospheric system to 6.912 mL/minute in a vacuum system. This desalination system turned out to be able to improve the quality of brackish water, from non-potable water to water that meets drinking water quality standards in accordance with RI Minister of Health Regulation No. 492 of 2010.
Preparation and characterization of Pd93Cu7/Al2o3 composite membrane for hydrogen permeation
Authors: Sari Ratna , Mulyati Sri , Dewi Ratni , Hakim Lukman
Published: June 2019

In this work, an electroless plating technique was used to prepare Pd-Cu coated ceramic alumina membranes tube. The composition, surface morphology and cross-section of the Pd97Cu7/Al2O3 membrane is investigated by energy-dispersive spectrometry (EDS), and scanning electron microscopy (SEM). Hydrogen permeation and selectivity across a membrane is measured using pressure difference (1.05-1.5) at a temperature range (573-773 K). The reported membrane obtained a high flux of 3.4 mol H / ms at a temperature of 723 K, while the selectivity is above 75 for H2 / N2.