bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single-frequency, linearly polarised fibre laser with spectrally asymmetric fibre Bragg grating mirrors
Authors: Belovolov M.I. , Paramonov V.M. , Medvedkov O.I. , Belovolov M.M. 
Published: November 2019

Abstract
A new design of a single-frequency fibre laser at a wavelength of 1.55 μm with linearly polarised output radiation is developed and investigated, in which a uniform Bragg grating written in an SMF-28 fibre is used as one mirror and the other mirror is a grating written in a Panda fibre with a small overlap of reflection spectral bands of mirrors and the possibility of fine tuning of the lasing spectral line. The length of the active part of the laser cavity formed by a fibre doped with the low-concentration Er3+ erbium ions is 10 cm. At a pump power of 60 mW and a wavelength of 1.48 μm, the lasing power reaches 100 μW and the width of the spectral line is less than 100 kHz.
Tunable single-frequency source based on a DFB laser array for the spectral region of 1.55 μm
Authors: Dudelev V.V. , Mikhailov D.A. , Andreev A.D. , Kognovitskaya E.A. , Lyutetskiy A.V. , Slipchenko S.O. , Pikhtin N.A. , Gladyshev A.G. , Denisov D.V. , Voropaev K.O. , Ionov A.S. , Babichev A.V. , Novikov I.I. , Karachinskii L.Ya. , Kuchinskii V.I. , Egorov A.Yu. , Sokolovskii G.S. 
Published: November 2019

Abstract
A technology of arrays of distributed-feedback semiconductor lasers for the spectral region of 1.55 μm and their characteristics are presented. Stable single-frequency lasing with a side mode suppression ratio higher than 25 dB is demonstrated. The possibility of continuous wavelength tuning in a range of up to 7 nm is shown.
Free-electron Auger quenching of the Fe2+ excited state in ZnSe
Authors: Il’ichev N.N. , Bufetova G.A. , Gulyamova E.S. , Pashinin P.P. , Sidorin A.V. , Tumorin V.V. , Kalinushkin V.P. , Gavrishchuk E.M. , Savin D.V. , Rodin S.A. , Ikonnikov V.B. 
Published: November 2019

Abstract
The influence of free electrons in Fe2+: ZnSe crystals on the nonlinear transmission of high-power laser radiation with a wavelength of 2940 nm at room and low temperatures is experimentally found. Fe2+ : ZnSe samples additionally doped with Al are used. The transmission of an Al : Fe : ZnSe sample with electron conduction in a strong (peak intensity about 4.6 MW cm−2) field is almost the same as in a weak field both at low and room temperatures. The absence of an increase in the transmission of this sample under the action of high-power radiation is explained by increasing absorption saturation intensity of Fe2+ at this wavelength due a decrease in the lifetime of the excited state of Fe2+. The decrease in the lifetime is related to the well-known Auger quenching of impurity luminescence in semiconductors by free electrons.
Energy characteristics of a supersonic continuous-wave chemical HF laser using hydrazine decomposition products
Authors: Fedorov I.A. 
Published: November 2019

Abstract
We report the results of calculations and experimental studies of specific energy characteristics of a supersonic cw chemical HF laser with a flat nozzle block corresponding to the nozzle – nozzle reagent mixing scheme, in which catalytic decomposition products of hydrazine N2H4 (H2 + N2 + NH3) are used as a secondary fuel. As a result of experiments with cold (300 K) model mixtures, the specific energy extraction of the laser is found to decrease in this case by 43 % compared with the laser utilising pure hydrogen. The calculations show that the main reason for a decrease in the specific energy of the laser is an increase in the temperature in the mixing zone of the oxidising gas and secondary fuel jets. A strong effect of ammonia is revealed. Taking into account the actual heating of the products (up to 1000 K) during the catalytic decomposition of N2H4 allows the level of specific energy extraction from the laser to approach that of energy extraction from the laser operated on pure hydrogen by 13 %, which will lead to a decrease in the specific energy extraction by only 30 % in the absence of NH3 decomposition products.
Optical fibres and fibre tapers with an array of Bragg gratings
Authors: Popov S.M. , Butov O.V. , Kolosovskii A.O. , Voloshin V.V. , Vorob’ev I.L. , Isaev V.A. , Vyatkin M.Yu. , Fotiadi A.A. , Chamorovsky Yu.K. 
Published: November 2019

Abstract
The properties of optical fibres with an array of fibre Bragg gratings written directly during the fibre drawing are considered. Such optical fibres offer new possibilities for producing new types of active and passive fibre elements due to the enhanced back-reflected signal of the so-called artificial Rayleigh scattering, and are of interest for modelling physical phenomena associated with the statistics of reflecting centres in optical fibres, such as, e.g., localisation of photons. We studied fibres with an array of Bragg gratings written in photosensitive fibres, ordinary single-mode optical fibre of the SMF-28 type and in fibre with a core doped with erbium ions. To control the spectrum width of the reflected signal, we used chirped phase masks, as well as writing arrays of gratings in tapered optical fibres.
Combining fiber Brillouin amplification with a repeater laser station for fiber-based optical frequency dissemination over 1400 km
Authors: Koke Sebastian , Kuhl Alexander , Waterholter Thomas , Raupach Sebastian M F , Lopez Olivier , Cantin Etienne , Quintin Nicolas , Amy-Klein Anne , Pottie Paul-Eric , Grosche Gesine 
Published: November 2019

Abstract
We investigate optical frequency dissemination over a 1400 km long fiber link in looped configuration over a pair of underground fibers between Braunschweig and Strasbourg. This fiber link is the first to combine fiber Brillouin amplifiers with a repeater laser station. Phase-coherent operation over more than five days is demonstrated. We analyze the repeatability of the performance over four campaigns and present results of 65 d in total. The weighted mean of the fractional frequency offset of the transferred optical frequency over the complete data set is (−1.1 ± 0.4)×10–20. By analyzing the stabilization signals of the two individual fibers, the correlation of the phase noise on the two fibers is shown to be >98%.
A model of predator-prey differential equation with time delay
Authors: ‘Arifah H , Krisnawan K P 
Published: November 2019

Abstract
This paper purposes are forming a predator-prey model with delay, examining the stability of the fixed points, and observing the presence of bifurction of the fixed point. The predator-prey models formed by using a type II-Holling function and a logistic equation. Holling function is a function that shows the predation level of a predator against its prey. This level of predation depends on how the predator searches, captures, and finally processes the food. The stability of fixed points of the predator-prey model with this delay observed through its model linearity. And the bifurcation is indicated by the sign changing of eigen values over the change of parameter value and from the decrease of the number of fixed points. The results show that at a certain value of parameter the 3 fixed points decreased to only 2 fixed points. At this certain parameter value, the first fixed point is saddle and the second one is degenerate. The system indicating undergoes a transcritical bifurcation.
Hopf bifurcation of actuated micro-beam nonlinear vibrations in micro electro mechanical systems
Authors: Krisnawan K P 
Published: November 2019

Abstract
In this paper, the effects of micro-beam stiffness changes to the dynamic of nonlinear vibrations are investigated. Nonlinear vibrations equation of an actuated micro-beam is derived based on Euler-Bernoulli beam theory. Galerkin method is adopted to simplify the nonlinear equation of the motion. The simpler equation transformed into a dynamical system and its eigen values are analysed. To show the dynamic of the system, the bifurcation and phase plane diagrams are drawn. The numerical result showed that the change of micro-beam stiffness exhibits a Hopf bifurcation.
How to design open-ended questions? : Literature review
Authors: Agustianingsih R , Mahmudi A 
Published: November 2019

Abstract
There are two types of questions that teachers can use in the learning process, that is closed-ended and open-ended questions, but only open-ended questions that can stimulate the students to develop their higher-order thinking skills. Although this type of question has an important function for students, it turns out the questions contained in the textbook are still in the form of closed-ended questions and to design open-ended questions takes a lot of time and effort. Therefore, a literature study is needed to find simple strategies that can be used to design open-ended questions. Based on the findings, there are 5 strategies that can be used to design open-ended question, namely modifying closed-ended questions, working backward, design the questions to determine “who is correct?”, using the problem-posing principle and design the questions to determine “what’s wrong with this?”. The results of this literature review also found that open-ended questions can also be used to identify students’ conceptual understanding, reasoning and misconception.
Scientific Learning and Its Contributions to Increase the Student’s Self Confidence and Learning Outcomes
Authors: Noer S H , Gunowibowo P 
Published: November 2019

Abstract
This study aims to determine the contribution of scientific learning in terms of Problem Based Learning (PBL), Contextual Teaching and Learning (CTL), and Guide Discovery Learning (GDL) to student’s self-confidence and learning outcomes (critical thinking ability and mathematical representation). The population in this research is students of eight-class from State Junior High School in Bandar Lampung City which is distributed in 31 schools. The samples of the study were students from three selected schools representing high-rank schools, middle-rank schools and low-rank schools. The sample was chosen by purposive random sampling technique. The research design is Pre-test Post-test Control Group Design. The results showed that (1) student’s self-confidence in CTL and student’s self-confidence in PBL were higher than student’s self-confidence in conventional learning, (2) student’s self-confidence in GDL did not differ from student’s self-confidence in conventional learning; (3) student’s mathematical critical thinking skills in CTL and student’s mathematical critical thinking skills in PBL are higher than student’s mathematical critical thinking skills in conventional learning; (4) student’s mathematical representation in GDL is higher than student’s mathematical representation in conventional learning. Related to the completeness of the student’s learning outcomes, it is known that: (1) the percentage of students who have critical thinking skills are good-categorized in the CTL class and in the PBL class is more than 60% of the total number of students; (2) the percentage of students who have mathematical representation are good-categorized in the GDL class is not more than 60% of the total number of students. Thus it can be concluded that in general, scientific learning contributes to the development of self-confidence and student’s learning outcomes.
Analysis of Sixth Graders’ Difficulties in Solving Mathematics Word Problems on Whole Numbers, Fractions, and Decimals
Authors: Kusuma U I , Retnawati H 
Published: November 2019

Abstract
Operation which involve whole numbers, fractions, and decimals are important concepts that must be possessed by students. It is a part of mathematics that is very close to everyday life. In fact, many students who have difficulty in understanding the fractions, especially in the word problems. This study aims to describe sixth graders’ difficulties in solving mathematics word problems on the operation which involve whole numbers, fractions, and decimals. This research is descriptive with students of grade six as the subjects. Data were collected by tests and in-depth interviews. Tests were used to analyze students difficulties in solving mathematics word problems on the operation which involve whole numbers, fractions, and decimals. Interviews were conducted to know the difficulties experienced by the students in depth. The unstructured interviews were conducted with students’ error. The results showed that students’ difficulties in solving mathematics word problems on the operation which involve whole numbers, fractions, and decimals are caused by: 1) Students’ difficulties in the word problem, 2) Students’ difficulties in understanding the concept of fractional operations, 3) Students have less numeracy skills, and 4) Inaccuracy.
Learning how to reason in geometry supported by video in YouTube
Authors: Asmaranti W , Retnowati E 
Published: November 2019

Abstract
YouTube is very populer. Indeed, there are learning resources in the form of videos that can be found in YouTube. The purpose of this study is to describe whether these videos are useful for students. In this research, two students were given three new geometry problems to solve. The first student always watches Korean movies in YouTube, and the second one rarely watches such video in YouTube. They were asked to search relevant information in YouTube while trying to solve the geometry problems. Specifically, their reasoning ability is assessed including how they pose arguments, visualise a context, identify concepts, and conclude the solution. The results showed that after learning to use videos in YouTube, the reasoning abilities of the first student improved. Whereas the second student had difficulty using the searching bar in YouTube finding keywords so that the second student does not solve the given problem. It is concluded that learning using videos in YouTube is very helpful, but it is important to have sufficient knowledge on how videos in YouTube are searched and used.
GARCH(1,1) model with the Yeo–Johnson transformed returns
Authors: Nugroho D B 
Published: November 2019

AbstractOne of the most popular class in modeling financial volatility is GARCH-type model. Several extensions to the basic GARCH model have been developed to be more flexible in capturing various characteristics of financial time series data. In this study, a new class of GARCH models is proposed by applying Yeo–Johnson transformation to the return series. The proposed model is estimated by employing adaptive random walk Metropolis (ARWM) method in Markov chain Monte Carlo (MCMC) scheme. Our empirical results on the GARCH(1,1) models showed that the proposed model outperformed the initial model in fitting ten different international stock indices.
MCMC Algorithm for Bayesian Heterogeneous Coefficients of Panel Data Model
Authors: Jaya I G N M , Tantular B , Zulhanif  , Ruchjana B N 
Published: November 2019

Abstract
Panel data models have been applied widely in many subject areas related to economic, social, and epidemiology. In some cases (e.g. epidemiology studies), the phenomena encountered have a complex relationship structured. The risk factors such as house index, healthy behaviour index, rainfall and the other risk factors of particular infectiouse disease may have different effect on the outcome due to the heterogeneity of crossection units. The effect of the covariates on outcome could vary over individual and time units. This condition is called as a non-stationary or instability relationship problem. This problem leads to bias and inefficient of the estimators. It is important to examine the heterogeneous coefficients model for avoiding inefficient estimator. We present in detail a statistical estimation procedure of the heterogeneous coefficients for fixed effect panel data model by means of the hierarchical Bayesian estimation approach. The challenges of the Bayesian approaches are finding the joint posterior distribution and developing the algorithm for estimating the parameters of interest. We find that the joint posterior distribution of the heterogeneous coefficients fixed effect panel data model does not follow any standard known distribution form. Consequently, the analytical solution cannot be applied and simulation approach of Markov Chain Monte Carlo (MCMC) was used. We present the MCMC procedure covering the derivation of the full conditional distribution of the parameters model and present step-by-step the Gibbs sampling algorithm. The idea of this preliminary research can be applied in various fields to overcome the non-stationarity problem.
Path analysis for determining health factors in Indonesia
Authors: Nurmawati W P , Kismiantini  
Published: November 2019

Abstract
Health status of a population plays an important role in developing a country. A better health can promote economic growth and foster development of the country. The aim of this study was to investigate relationships among age, sex, weight, height, smoking behavior, and blood pressure on health status of adults in Indonesia. The path analysis was constructed using the secondary data of the fifth wave of the Indonesian Family Life Survey in 2014/2015. This survey was a large national survey with representing about 83% of the Indonesian population. The sample comprised 24,263 adults aged older than 17 years. The hypothesized model suggested that age, sex, weight, height, and smoking behavior had an effect on blood pressure and that all variables influenced health status. All path coefficients were statistically significant. The age, gender, and weight variables had positive relationships with blood pressure while in the opposite direction to the height and smoking behavior. The blood pressure, age, and smoking behavior had negative relationships with health status while in the opposite direction to the sex, weight, and height. Short male respondents who ever smoked and had high blood pressure were reported to have poor health status as age increased and weight decreased.
Fundamental homomorphism theorems of fuzzy subsemigroups
Authors: Karyati Karyati 
Published: November 2019

Abstract
The aim of this paper is to define and prove the properties of the homomorphism of fuzzy subsemigroup. This is the revised of the previous research has been done by the author. In this research we use different method to prove the fundamental theorem, i.e. using the properties of the alpha cut of the fuzzy subsemigroup. We got the result, based on the properties of alpha cut of a fuzzy subsemigroup, it is obtained a property that a semigroup is a fuzzy subsemigroup if and only if the alpha cut of the subsemigroup fuzzy is a semigroup. We also can prove that the fundamental homomorphism theorem of semigroup is valid for the fundamental homomorphism theorem of fuzzy subsemigroup.
Classification of provinces in Indonesia based on 2014 presidential election participation levels using fuzzy c-means
Authors: Yuswatun A , Abadi A M 
Published: November 2019

Abstract
The presidential and vice presidential elections held every five years is a benchmark for democracy in Indonesia. However, the expected level of participation cannot be achieved. Election socialization as an effort to increase the level of participation in each province is different because the level of participation in each province is also varied. Therefore, there is a need of regional grouping based on the level of electoral participation in order to facilitate the electoral socialization process. This study uses fuzzy c-means with two attributes, namely the number of voters and the number of voting rights users. All provinces in Indonesia are classified into two clusters. If the provincial participation rate is below the national participation standard (69.58%) then the province is considered to have a low participation rate and vice versa. Therefore, the first cluster constitutes provinces with high electoral participation rate and the second cluster constitutes provinces with low electoral participation rate. The results of the classification are 9 provinces in first cluster and 24 provinces in the second cluster.
Dynamics of a mathematical model of cancer cells with chemotherapy
Authors: Lestari D , Sari E R , Arifah H 
Published: November 2019

Abstract
As commonly known, cancer is one of the fatal diseases to which considerable attention needs to be paid. The purpose of the research concerned here was to form a mathematical model of the spread of cancer with chemotherapy and to know the dynamics of its solution. As for the stages in achieving the purpose, they were forming a mathematical model, determining the point of equilibrium, determining the basic reproduction number, analyzing the stability around the equilibrium point, and conducting numerical simulation with the parameters given. The pattern of how cancer cells spread could be modeled in the form of a mathematical equation according to the system of differential equation. From the system formed, an equilibrium solution and an analysis of the behavioral dynamics of the cell spread with treatment in the form of chemotherapy were attained. Simulation with graphs indicates that the growth rate of cancer cells influences the population of the said cells. The greater the growth rate of cancer cells, the greater the population of those cells. Besides, it is also obtained that the increasing dosage of the drug given with the limits allowed, the lower of those cancer cells.
Mathematical resilience: Is that affecting the students’ mathematics achievement?
Authors: Rokhmah K N , Retnawati H , Solekhah P 
Published: November 2019

AbstractMathematical resilience is an attitude that necessary for the student to respond positively in the face of difficulties in study mathematics. The difficulties in study mathematics may influence the students’ mathematics achievement. The purpose of this research is to describe the relation between students’ mathematical resilience and students’ mathematics achievement. This research involves quantitative descriptive study. The researcher collected data with two types of instruments, test and non-test instruments. The instruments are mathematics achievement test and mathematical resilience questioner. The participants of this study consisted of 28 students from a health vocational high school in Yogyakarta, Indonesia. The results indicate that there is no relation between mathematical resilience and student’s mathematics achievement. More findings and suggestions will be explained in the text.
Prospective mathematics teachers’ understanding of pedagogical knowledge: what and where it came from
Authors: Solekhah P , Retnawati H 
Published: November 2019

Abstract
Pedagogical Knowledge (PK) is one of teachers’ knowledge that important in teaching and learning process. Prospective mathematics teachers’ development in the PK is the key to its successful implementation. This research aims to describe prospective mathematics teachers’ understanding about PK and their opinions about university mathematics education courses that contribute. The research was a qualitative research using phenomenological approach. Data were collected through in-depth interview followed by focus group discussion (FGD) that involved 6 final-years mathematics education students and 5 professional teacher program students in Yogyakarta State University, both have done micro-teaching practice. The data were analysed by means of Cresswell’s step. The result of the study showed that prospective mathematics teachers have been able to explain PK and has mentioned the elements of PK. However, they had various opinions about which courses contribute to the development of their own PK. But, the implementation of these lectures still needs to be improved, such as advice from the prospective mathematics teacher, which is to expand teaching practices and update information about the system that applies in the school.