bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new liquid density measurement method based on elastic spring stretching
Authors: Kovačević Milan S , Milošević Marko M , Cimbaljević Željko M 
Published: March 2021

Abstract
A simple method is described for measuring liquid density based on stretching of the spring and equilibrium of weight and elastic force. The method involves placing a container with liquid under test on the spring causing a stretch of the spring that is directly proportional to the weight of the liquid. With this technique, the liquid density can be determined without measuring its mass and volume, and it should help students comprehend the concept of density more easily. The design of the measuring setup in this study is made using tools and materials that are simple and easy to obtain, such as spring, ruler, and small plastic or metallic container (tube). Two liquids used to test the measuring method were ethanol and glycerol. A test showed that the density of the test liquids at room temperature could be measured with the relative uncertainty of 3%, hence the reliability of the described method was confirmed.
Don't cross the streams: caustics from fuzzy dark matter
Authors: Dalal Neal , Bovy Jo , Hui Lam , Li Xinyu 
Published: March 2021

Abstract
We study how tidal streams from globular clusters may be
used to constrain the mass of ultra-light dark matter particles,
called `fuzzy' dark matter (FDM). A general feature of FDM models
is the presence of ubiquitous density fluctuations in bound,
virialized dark matter structures, on the scale of the de Broglie
wavelength, arising from wave interference in the evolving dark
matter distribution. These time-varying fluctuations can disturb
the motions of stars, leading to potentially observable signatures
in cold thin tidal streams in our own Galaxy. The study of this
effect has been hindered by the difficulty in simulating the FDM
wavefunction in Milky Way-sized systems. We present a simple method
to evolve realistic wavefunctions in nearly static potentials, that
should provide an accurate estimate of this granulation effect. We
quantify the impact of FDM perturbations on tidal streams, and show
that initially, while stream perturbations are small in amplitude,
their power spectra exhibit a sharp cutoff corresponding to the de
Broglie wavelength of the FDM potential fluctuations. Eventually,
when stream perturbations become nonlinear, fold caustics
generically arise that lead to density fluctuations with universal
behavior. This erases the signature of the de Broglie wavelength in
the stream density power spectrum, but we show that it will still be
possible to determine the FDM mass in this regime, by considering
the fluctuations in quantities like angular momenta or actions.
Self-tuning kinetic gravity braiding: cosmological dynamics, shift symmetry, and the tadpole
Authors: Bernardo Reginald Christian 
Published: March 2021

Abstract
We study the self-tuning subclass of kinetic gravity
braiding and obtain robust predictions on self-tuning and dynamics
in the tadpole-free shift symmetric sector of the theory. In
particular, we show inevitability of cosmic acceleration, prove the
dynamical stability of this late-time asymptotic state, and derive
ghost and gradient stability constraints on the self-tuning
vacuum. We discuss the results concretely in the context of
generalized cubic covariant Galileon theory and an exponential
kinetic gravity braiding.
Generation of super strong longitudinal electric field via vector superposition of linearly polarized laser beams
Authors: Zhang Jun , Wu Zhenhai , Long Jiao , Xiong Qian , Zheng Jiangang , Zhao Junpu , Zhang Xiongjun , Zheng Kuixing , Wei Xiaofeng 
Published: March 2021

Abstract
Radially polarized laser beams, which could generate longitudinal electric fields (LEF) in the far field after being focused have drawn increasing interest in wide fields. However, it is difficult to boost a radially polarized laser pulse to high peak power due to its spatially inhomogeneous polarization distribution. Here, we propose a vector superposition approach, firstly partition a linearly polarized beam into two parts in the near field, secondly modulate their polarization direction separately using the electro-optical effect and finally focus them using a high numerical aperture lens, thereby generating the LEF in the far field owing to vector superposition. This approach can amplify a laser pulse to the required peak power by using traditional schemes of the linearly polarized seed-pulse generation and multi-pass amplification, thereby efficiently scaling the LEF to the required magnitude. The simulation results support the theory in concluding that the approach would be a competent way to achieve super strong LEF in the far field of a laser beam.
GPR geophysical method as a remediation tool to determine zones of high penetration resistance of soil
Authors: Akinsunmade A , Tomecka-Suchoń S , Kiełbasa P , Juliszewski T , Pysz P , Karczewski J , Zagórda M 
Published: March 2021

Abstract
In this study, we demonstrated application of ground penetrating radar towards assessing zones of high penetration resistance (PR) within soil horizons with a view to characterize the subsurface media. Soil attributes changes both in time and space can be difficult to understand. This may be largely due to concealing nature of subsurface media and convectional methods of soil investigations that are usually restricted to observation at the surface and discrete points. Thus making interpolations, inferences and conclusions from such methods inadequate and less reliable. However, ground penetrating radar (GPR) – a geophysical method of investigation was used in this study in lieu of the traditional methods. Soil variability measured in its PR (strength) is related to its compactness-function of bulk density. GPR utilizes electromagnetic (EM) energy in the range of 10 MHz to 3GHz that propagates through the investigative materials. Analysis of the two-way travel time of EM wave gives information about the velocity of the travelling wave. Data were acquired on a loamy silty soil at a farmland in Krakow as a test site simulated with compaction by tractor passes to induce densification of the subsurface layers. Results of the test depicted distinguishing feature of the compacted zones which is reduction in (EM) waveform amplitude and rapid decay of the EM frequency spectra. The research outcome shows swift, cheap and less cumbersome method of soil investigation.
Incorrect problem analyzing in the Finite Element Method
Authors: Firych-Nowacka A , Smolka K 
Published: March 2021

Abstract
Nowadays, numerical methods are widely used in the field analysis of many electromagnetic devices, MEMS and more. Incorrect problem analysis using the Finite Element Method often leads to incorrect results and drawing wrong conclusions. Therefore, the role of the engineer who describes the model in the pre-processing stage cannot be forgotten. This paper presents an example of developing a computer model of a flat capacitor in FEMM program, using the 2-dimensional Finite Element Method. It has been shown, how simple can disturb the result after wrong input data implementing.
Soldered joints of Ag electrode to ultra-thin metallic Au layer on ceramic substrate
Authors: Lebioda M , Pawlak R , Rymaszewski J 
Published: March 2021

Abstract
Among various methods of microjoining applied to electronic equipment soldering technologies are of great importance. In the construction of sensors a technique of a reflow soldering, common for microelectronic devices assembly, is rather not applicable because of the unique design of the sensor. Connecting external leads to thin metal layer of contact pads is a particular challenge. Special requirements are placed on devices and joints operating at cryogenic temperatures. The joints operating in cryo-temperatures should be characterized by good and stable electrical conductivity, tightness and the required mechanical strength. In the paper the new method of soldering of Ag leads to thin Au layer on ceramic substrate is presented. A special feature of the new soldering method is the very short time (2-3 seconds) in which the solder (In) is in the liquid state. The manufactured joints are characterized by a very low resistance as well as a linear and continuous current-voltage characteristic in the temperature range of 15 to 300 K.
Assessment of the degree of secondary luminescence generated by industrial hemp seeds
Authors: Miernik A , Kiełbasa P , Korenko M , Zając M 
Published: March 2021

Abstract
The trial was undertaken to measure the amount of different types of seeds industrial hemp. Photonic analysis was used to make measurements which bases on counting the amount of emitted photons from standardized sample within estimated time interval. Photon emission tests were carried out in the Laboratory of Experimental Research Techniques of Raw Materials and Biological Products with PCA accreditation in the subject measurement procedure.
Modelling short-circuit current of a 21 MVA HTS superconducting transformer
Authors: Surdacki P , Jaroszyński L , Woźniak Ł 
Published: March 2021

Abstract
The paper presents a computer model of an HTS 21 MVA 70/10.5 kV two-winding superconducting transformer. The model takes into account the influence of temperature and current intensity on electrical and thermal properties of windings made of two types of second generation superconducting tape differing in the presence of copper stabilizer. Rhyner’s power law was used to describe the transition to the resistive state of the YBCO superconductor layer. A model of the non-linear magnetic core of the transformer was developed by using modified Jiles-Atherton equations. The proposed model allows numerical determination of current, resistance and winding temperature waveforms during an operating short circuit of a 21 MVA superconducting transformer.
Numerical Thermomechanical Viscous 2D Material Rheology Modelling Enhanced by Marker-in-Cell (MIC) Technique
Authors: Irwandi I. , Umar Muksin , Khaizal  , Sudarmaji  
Published: March 2021

Abstract
The rheology of a material especially related to mechanical behaviour is an important characteristic. Rheology has wide applications for example in nanomaterials, engineering design, biology, and in a large scale case in geodynamics study. Rheology relies on several physical equations such as continuity equation, momentum equation, gravity potential, state equation, heat transfer, and advection equation. The equations seem to be simple, however, the application of those equations to a real case is not easy and causes many numerical problems. Marker-in-Cell (MIC) is a technique to solve a numerical rheology modelling problem especially diffusion of sharp gradients during the advection process. The technique successfully simulates the advection process for thermomechanical viscous material for a 2-dimensional case study. The model was initially set up two parts with laterally contrast difference of material characteristics. The lateral density difference of material induced gravitational force and generated circular movement of material. After the simulation was run for the 20-time step, the whole material moved more clockwise circulation. The model started to be stable when all denser material at the lower layer and lower density material at the upper part. The model was fully stable and become at a stationary state at a time more than 100-time steps. The final simulation result showed that the MIC algorithm successfully simulated the conversion process involving the thermomechanical mechanism with diffusion error control and without breaking the contrast density of the material.
An analysis of 4c skill on heat in facing the industrial revolution era 4.0
Authors: Daulay Nora Hawari , Sani Ridwan Abdullah , Rahmatsyah  
Published: March 2021

Abstract
The purpose of writing this article is to find out how to build human character to face the industrial era 4.0, so that they have an understanding of digital literal dimensions and can increase the graduates’ competence who have 4Cs skills (critical thinking, creativity, collaboration, and communication) by using collaborative inquiry, especially on temperature and heat material. This type of research is a quasi experiment with a pretest-posttest control group design. The result of this research is that students 4Css skills using collaborative inquiry learning model are better than students4Cs skills using conventional learning at SMA Negeri 14 Medan. Then, it is hoped that they will be able to produce humans who are in accordance with the demands of the industrial era 4.0. With 4Cs skills, they can gain and increase cooperation in a group to solve certain problems, increase their tolerance for peer opinions, try to think critically and creatively to solve problems related to something.
Analysis of critical and creative thinking skills on the topic of static fluid physics with guided inquiry learning assisted by computer simulation
Authors: Ratna Salwa Dwi , Simanjuntak Mariati P. , Sahyar  
Published: March 2021

Abstract
This study aims to analyze student’s critical thinking skills and creative thinking skills on the topic of static fluid physics using guided inquiry learning assisted by computer simulations. This type of research is a quasi experiment with the design of three groups pretest-posttest. The sampling technique uses cluster random sampling. Analysis of research data using multivariate analysis of variance (Manova). The results showed that student’s critical thinking skills and creative thinking skills on the topic of static fluid physics using guided inquiry learning assisted by computer simulations were better than using guided inquiry learning without assisted by computer simulation or conventional learning.
Setting the natural gas selling price through pipeline network optimization and project feasibility study
Authors: Nurprihatin Filscha , Andry Johanes Fernandes , Tannady Hendy 
Published: March 2021

Abstract
Natural gas will play an important role in the energy revolution, but its construction is still costly. Natural gas transport pipeline network shoulders the task of gas supply, which plays a significant role in improving the overall socio-economic benefits for the region. Pipeline network optimization design is a complex problem, involving many variables. In this study, the location of the Distribution Center is considered and was obtained from the previous study. This study also considers the distance between locations of households. The Minimum Spanning Tree (MST) is applied to obtain the pipeline network length. Then, the calculation is proceeded through the Benefit-cost Ratio in determining whether this project is feasible or not. Although the MST result shows the pipeline is longer than the previous work, studies have shown that the project is still feasible to run. The study also explains that the government can still sell gas at a lower price in the break-even condition.
Contribution of observing indicators to temperature and heat experiments in improving science process skills
Authors: Purba Nita Ariany , Derlina  , Siregar Alkhafi Maas 
Published: March 2021

Abstract
This study aims to determine whether there are significant differences in the science process skills of students who are taught using the 5E learning cycle model with students who are taught using conventional learning and what indicators play a role in increasing students’ science process skills. This research is a quasi-experimental study with two group pretest-posttest designs. The population of this study was students of class XI of SMA Negeri 4 Pematang Siantar consisting of 8 classes. The sample in this study was taken by cluster random sampling technique, namely as many as two classes, where class XI MIPA 7 as an experimental class taught with learning cycle model 5E and class XI MIPA 8 as a control class taught with conventional learning. The instrument used was a non-test instrument for science process skills in the form of student worksheets. Data will be analyzed using the SPSS program. The results of the study concluded that there were significant differences in the science process skills of students who were taught using the 5E learning cycle model with students who were taught using conventional learning and observing indicators had a significant contribution in improving students’ science process skills.
Phythochemical and Toxicity of Ethanol extract Sijukkot Leaves (Lactuca IndicaL)
Authors: Riris Ida Duma , Silalahi Albinus , Juwitaningsih Tita , Damanik Marini , Susanti Nora 
Published: March 2021

Abstract
Phytochemical screening on Sijukkot which determined as Lactuca indica L, the plants from an area in the village of Parsaora Sibisa Ajibata, Toba Samosir, North Sumatera has been done. Test was carried out to determine the composition of secondary metabolites contained in these plants. It was started by extracting plant leaves using 96% ethanol. Phytochemical test was used to identify compounds from the ethanol extract of sijukkot leaves. The identification results obtained compounds as Flavonoids, tannins, saponins, steroids and triterpenoids. Furthermore, the toxicity test was carried out using the BSLT method and the results showed LC50: 11.644 ppm, thus the ethanol extract of the leaves had a strong toxicity.
Household electricity consumption in rural area: An occupant’s behavior analysis to increase energy saving
Authors: Akil Yusri Syam , Wardi  , Muslimin Zaenab , Taufik Imran 
Published: March 2021

Abstract
This research investigates electricity consumption and typical occupants’ behaviors for rural households in Indonesia. A questionnaire is composed to get important information from respondents through direct survey located in several rural areas in Bone, South Sulawesi province as a case study. The information included such as owned household appliances, occupants’ behaviors regarding appliances usage, factors barriers in buying energy saving appliances (ESA), and general barriers in electricity saving. To get more information, regression analysis is also applied to identify relationship between perception and consumption habits. Results of this study show lamp, washing machine, and television are low watt appliances which majority owned by users with installed electricity at home is between 450 VA to 1,300 VA. A main barrier to have ESA is price, and lack information to support practising electricity saving. Next from regression results, perception variable is found affected usage behavior and also daily habit of occupants. Output of this study gives more insight in understanding characteristics of electricity consumption for rural households. They can be used as a basis in making effective energy saving program to dealing with issue related to growth load in power systems.
Analysis of land use changes for green open space (gos) in tebingtinggi city
Authors: Lubis Darwin Parlaungan , Nurwihastuti Dwi Wahyuni , Sintong Mahara 
Published: March 2021

Abstract
This study aimed to 1) Analyze land use change that has occurred in each sub-district in Tebing Tinggi City for 6 years (2014 - 2020), 2) Analyze the factors influencing the dynamics of changes in the use of green open space into a built-up area in the Tebing Tinggi City. The method used in this research was a survey method. The research design was performed in 3stages; (1) Literature study, (2) Data collection, (3) Discussing the processed data. The results showed that 1)Tebing Tinggi City had experienced very dynamic land use change. The biggest land use change was the built-up area, including a residential area, which increased by 370.95 hectares, the industrial area increased by 14.8 hectares, and the service area increased by 7.5 hectares. Meanwhile, vegetated land, such as rice fields decreased to 137,7 Ha. The mixed plantation land area decreased to 255.54 Ha. 2) The factors influencing land use change indicate that residential land has a significant effect on changes in GOS with a p-level value of less than 0.05 and is positive. It shows that each addition of residential land in a sub-district reduced the area GOS change to the built-up area of 0.016 Ha.
The influence of gasoline fuel additive on the motorcycle PM0.1 emission factor
Authors: Wardoyo A Y P , Majid I , Budianto A , Adi E T P 
Published: March 2021

Abstract
Fuel additive has been known to improve vehicle performance by raising the octane number or cleaning the combustion system. The performance enhancement might affect vehicle emission. In this research, we aim to investigate the impact of fuel additives on the PM0.1 emission. The commercial additives were evaluated based on the factory’s recommended concentration for the mixture fuel. The additive effect on the PM0.1 emission was investigated by measuring the PM0.1 concentration emitted by the motor engine operated using fuel with and without additives. The PM0.1 concentrations were measured using a TSI P-TrakTM Ultrafine Particle Counter Model 8525. The exhaust emission was injected into the chamber for 100 seconds for the PM0,1 concentration measurement. The emission factor was calculated by the total PM0.1concentration per the volume of the burned fuels. The result shows that fuel additives reduce the PM0.1 emission factor depending on the type of the additive. additives reduce the PM0.1 emission factor depending on the type of the additive.
NodeMCU-Based Automatic Motorcycle Tire Pump Monitored by Android Smartphone
Authors: Rahayu Siti Utari , Mulia Rajagukguk Tri Marta 
Published: March 2021

Abstract
This study aimed to design a motorcycle tire pump that uses an Android smartphone as a display of the pressure read during the pumping process, besides LCD. The motorcycle tire pump in this study is based on the NodeMCU so that the read data can be connected directly to the Android smartphone via WIFI (ESP 8266), which is already available on the microcontroller. The pressure sensor used is the MPX5700AP; the data read from the device during the pumping process can be monitored by using Blynk app that is available on the Google Play Store. The output accuracy of this sensor can be directly compared or verified with a standard pump pressure gauge, which is connected to the pump. Based on the test results, once the device is connected to the power source via adaptor, the pump works and the device provides data readings, which are displayed on the Blynk app. The defined threshold pressure is 28 psi, so the relay will switch off the pump automatically if the pressure is equal to or more than 28 psi. After testing the device for four times, the average accuracy was 0.75 %. This result indicates that the device can work quite accurately and can be used to pump the motorcycle with the appropriate pressure.