bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trends in Changes in Primary Phytoplankton Production According to Remote Sensing Data in the Deep-Sea Region of the Black Sea for 1998–2015
Authors: Kovalyova I. V. , Finenko Z. Z. , Suslin V. V. 
Published: August 2023

The analysis of long-term seasonal changes in the concentration of chlorophyll, the maximum rate of phytoplankton photosynthesis and water temperature in the surface layer of the open waters Black Sea from 1998 to 2015 has been carried out. The trends of these indicators were assessed. For the research, we used the data of satellite observations SeaWiFS and MODIS-Aqua, MODIS-Terra. Typical positive temperature trends of 4 % in the deep-water western part of the sea. An annual temperature rise in deep-water areas was noted in the western cyclonic circulation by 0.038 °C. According to average annual data in other areas, no increase was found. The increase was mainly due to the winter season. Negative trends of primary phytoplankton production within 16.4–18.6 % of the initial level according to average annual values throughout the deep-water area. Significance level — p < 0.1. A decrease in primary production was observed in the summer. There were no statistically significant directional changes in chlorophyll concentration based on averaged data over 18 years. In different parts of the deep-sea area, the direction of interannual and seasonal changes in all indicators was similar. The emerging trend towards a decrease in phytoplankton productivity in recent years may lead to a restructuring of the phytoplankton community.
Spectral Light Absorption Coefficient of Particles and Colored Dissolved Organic Matter in the Sea of Azov
Authors: Churilova T. Ya. , Efimova T. V. , Moiseeva N. A. , Skorokhod E. Yu. 
Published: August 2023

The research was carried out based on the results of measuring the concentration of chlorophyll-a (TChl-a), spectral coefficient of light absorption by phytoplankton, non-algal particles (NAP) and colored dissolved organic matter (CDOM) in the southern part of the Sea of Azov in different seasons from 2016 to 2020. New data for the Sea of Azov on the variability of the spectral coefficient of light absorption by all optically active components have been obtained. A high (more than an order of magnitude) variability of all studied parameters was shown. The seasonal dynamics of TChl-a shows maxima in winter and summer. A relationship between the phytoplankton absorption and TChl-a has been revealed, which is described by a power function. Significant seasonal differences (two or more times) between the coefficients in the equation for parametrization of light absorption by phytoplankton were revealed. The NAP and CDOM light absorption were parametrized, the ranges of variability of the absorption coefficient and the exponential slope were revealed, and their seasonal dynamics was shown. Annual variability of absorption coefficient of NAP and CDOM was opposite to the annual cycle of TChl-a. The NAP and CDOM absorption coefficients increased after phytoplankton blooms, when TChl-a decreased. The relative contribution of phytoplankton, NAP, and CDOM to the total absorption by particles and dissolved matter at 440 nm varied significantly over the year. The share of phytoplankton was maximum in winter and summer, while in spring and autumn the maximum contribution to absorption was made by CDOM and NAP.
PENINGKATAN HASIL BELAJAR SISWA MELALUI MODEL PEMBELAJARAN NUMBER HEAD TOGETHER (NHT) PADA MATA PELAJARAN MATEMATIKA
Authors: Yusnani  
Published: August 2023

Tujuan dari penelitian tindakan ini adalah: mengetahui peningkatan motivasi Dan hasil belajar matematika setelah diterapkannya model pembelajaran Number Head Together pada siswa Kelas V SD Negeri 2 Srimulyo. Ingin mengetahui model pembelajaran Number Head Together dalam meningkatkan hasil belajar siswa terhadap materi pelajaran matematika setelah diterapkan model pembelajaran Number Head Together pada siswa Kelas V SD Negeri 2 Srimulyo. Penelitian ini menggunakan penelitian tindakan kelas (classroom action research) sebanyak tiga siklus. Setiap siklus terdiri dari empat tahap yaitu: rancangan, kegiatan dan pengamatan, refleksi, dan refisi. Sasaran penelitian ini adalah siswa Kelas V SD Negeri 2 Srimulyo. Data yang diperoleh berupa hasil tes akhir siklus, lembar observasi kegiatan belajar mengajar. Dari hasil analisis didapatkan bahwa hasil belajar siswa mengalami peningkatan dari siklus I sampai siklus III yaitu, (50,00%) atau ada 7 siswa yang telah tuntas dengan nilai tertinggi 80 dan terendah 48. Pada siklus II siswa yang telah tuntas sebesar (71,43%) atau 10 siswa dengan nilai tertinggi 85 dan terendah 55. Pada siklus III siswa yang tuntas sebesar (92,86%) atau ada 13 siswa dengan nilai tertinggi 98 dan terendah 63. sedangkan nilai rata-rata kelas diperoleh siklus I (65,21), siklus II (74,43) dan siklus III (80,00). Kesimpulan dari penelitian ini bahwa model pembelajaran Number Head Together dapat meningkatkan hasil belajar siswa.
UPAYA MENINGKATKAN AKTIVITAS DAN HASIL BELAJAR MATEMATIKA PADA MATERI LIMIT FUNGSI MELALUI METODE PEMBELAJARAN KOOPERATIF TIPE STAD SISWA KELAS XI IPS-1 SMA NEGERI 3 MATARAM TAHUN PELAJARAN 2022/2023
Authors: Made Ratna Dewi Ida Ayu 
Published: August 2023

Penelitian ini bertujuan untuk menguraikan upaya meningkatkan aktivitas dan hasil belajar matematika siswa kelas XI IPS-1 SMA Negeri 3 Mataram Tahun Pelajaran 2022/2023 pada materi pokok limit fungsi melalui metode pembelajaran kooperatif Tipe STAD. Penelitian ini menggunakan Metode Pembelajaran Kooperatif Tipe STAD. Metode penelitian yang digunakan adalah dengan model action research tipe classroom action research. Subjek penelitian ini adalah siswa kelas XI IPS-1 SMAN 3 Mataram tahun pelajaran 2022/2023 yang berjumlah 36 orang. Hasil penelitian menunjukkan bahwa penerapan Metode Pembelajaran Kooperatif Tipe STAD pada kelas XI IPS-1 SMAN 3 Mataram tahun pelajaran 2022/2023 pada Materi Pokok Limit Fungsi dapat meningkatkan aktivitas belajar siswa terlihat pada akhir siklus II mencapai hasil yang memuaskan, ditunjukkan dengan besaran angka prosentase sebesar 87,5% atau mengalami peningkatan sebesar 25% dari siklus I. Sementara di sisi lain, aktivitas siswa yang tidak relevan dengan pembelajaran mengalami penurunan yang cukup mengesankan sampai ke tingkat yang serendah mungkin, ditunjukkan dengan besaran angka prosentase rata-rata sebesar 12,5% pada akhir siklus II, atau mengalami penurunan sebesar 27,5% dari siklus I. Selanjutnya, terkait dengan hasil belajar dan ketuntatasan belajar siswa, penelitian tindakan ini telah berhasil meningkatkan hasil belajar dan atau ketuntasan belajar siswa sebesar 16,7% dari siklus I ke siklus II. Angka prosentase kenaikan hasil belajar siswa ini sudah jauh melampaui kriteria pengujian hipotesis yang telah ditetapkan, yakni sebesar 10% kenaikan dari siklus I ke siklus II. Dengan ini maka 85% lebih (tepatnya, 91,7%) dari siswa subyek penelitian ini telah mengalami ketuntatasan belajar, yang berarti juga telah melampaui batas kriteria ketuntasan yang telah ditetapkan dalam penelitian ini, yakni sebesar 85% siswa dalam kelas harus mencapai ketuntasan belajar sebagai syarat keberhasilan penelitian tindakan ini.
UPAYA MENINGKATAN PRESTASI BELAJAR MATEMATIKA MATERI TRANSFORMASI GEOMETRI MELALUI MODEL PEMBELAJARAN DISCOVERY LEARNING PADA SISWA KELAS IX DI SMP NEGERI 70 JAKARTA
Authors: Nurkomaria  
Published: August 2023

Penelitian dilaksanakan pada semester ganjil tahun pelajaran 2022-2023, yaitu pada bulan Oktober sampai November 2022. Penelitian berlangsung di SMP Negeri 70 Jakarta untuk mata pelajaran matematika, sebagai subjek dalam penelitian ini adalah siswa kelas IX, dengan jumlah siswa sebanyak 36 orang. Penelitian dilakukan dengan menggunakan pendekatan pembelajaran Discovery learning melalui penelitian tindakan kelas dua siklus, data penelitian diperoleh melalui tes hasil belajar, observasi keterlaksanaan Discovery learning dan observasi aktivitas siswa. Dari hasil penelitian diperoleh data telah terjadi peubahan tingkat prestasi peserta didik menjadi lebih baik. Hal ini terlihat dari perubahan hasil nilai rata-rata kelas dari 65,4 sebelum tindakan , namun setelah dilakukan tindakan pada siklus 1 menjadi 73,5 dengan ketuntasan belajar 58,3% sedangkan pada siklus II jumlah ketuntasan belajarnya naik menjadi 86,1 % dengan rata-rata hasil belajar 82,4 . Dengan demikian dapat dikemukakan bahwa pembelajaran dengan menggunakan pendekatan pembelajaran Discovery learning mampu meningkatkan prestasi belajar peserta didik terhadap materi Transformasi Geometri pada mata pelajaran Matematika di kelas IX SMP Negeri 70 semester ganjil tahun pelajaran 2022-2023.
PENINGKATAN HASIL BELAJAR MENULIS PUISI DENGAN MEDIA BERITA DI SURAT KABAR PADA SISWA KELAS X TKRO4 SMK NEGERI 1 TRENGGALEK
Authors: Etmiasih Sri 
Published: August 2023

Penelitian ini bertujuan untuk mengetahui peningkatan hasil belajar menulis puisi pada siswa kelas X TKRO4 SMK Negeri 1 Trenggalek Tahun Pelajaran 2018-2019. Penelitian ini menggunakan penelitian tindakan ( action research) sebanyak dua siklus. Setiap siklus terdiri dari empat tahap yaitu perencanaan, pelaksanaan, pengamatan, dan refleksi. Sasaran penelitian ini adalah siswa kelas X TKRO4. Data yang diperoleh berupa hasil tes menulis puisi. Berdasarkan pada pelaksanaan masing-masing siklus penelitian, maka dapat diambil kesimpulan, hasil belajar menulis puisi dengan media teks berita di surat kabar mengalami peningkatan. Hal ini dapat diketahui dari meningkatnya siswa yang memperoleh nilai yang sama atau lebih besar dari batas ketuntasan (70), meningkatnya rata-rata hasil belajar dan ketuntasan belajar setiap siklusnya. Sebelum siklus siswa yang tuntas denagn mendapatkan nilai yang sama atau lebih besar dari batas ketuntasan sebanyak 12 siswa dengan nilai rata-rata 66,14 dengan prosentase ketuntasan 34,26%, pada siklus 1 meningkat menjadi 24 siswa dengan nilai rata-rata 69,57 dengan prosentase ketuntasan 68,57 dan pada siklus 2 menjadi 29 siswa dengan nilai rata-rata 77,71 dengan posentase ketuntasan 82,26%. Kesimpulan dari penelitian ini adalah media berita di surat kabar dapat meningkatkan hasil belajar menulis puisi siswa kelas X TKRO4 SMK Negeri 1 Trenggalek tahun pelajaran 2018-2019 serta teknik ini dapat digunakan sebagai salah satu alternatif pembelajaran Bahasa Indonesia.
PENERAPAN MODEL PEMBELAJARAN TEAM ASSISTED INDIVIDUALIZATION (TAI) UNTUK MENINGKATKAN HASIL BELAJAR EKONOMI KELAS XII IPS 2 SMA NEGERI 3 MATARAM
Authors: R. Januar Widiatmoko  
Published: August 2023

Penelitian ini bertujuan untuk menguraikan penerapan model pembelajaran Team Assisted Individualization (TAI) untuk meningkatkan hasil belajar ekonomi kelas XII IPS 2 SMA Negeri 3 Mataram Tahun Pelajaran 2022/2023. Metode penelitian yang digunakan adalah dengan model action research tipe classroom action research. Subjek dalam penelitian ini adalah siswa kelas XII IPS-2 SMAN 3 Mataram semester gasal Tahun Pelajaran 2022/2023 yang berjumlah 36 orang. Penelitian ini dilaksanakan dalam 2 siklus, dimana setiap siklus meliputi tahap (1) perencanaan, (2) tindakan, (3) observasi, dan (4) refleksi. Data dikumpulkan dengan metode observasi, tes, catatan lapangan, dan dokumenter atau kepustakaan. Data yang diperoleh melalui observasi dianalisis untuk melihat ketercapaian indikator tindakan, sedangkan data yang diperoleh melalui tes dianalisis untuk melihat ketercapaian indikator kompetensi pengetahuan. Hasil penelitian menunjukkan bahwa penerapan model pembelajaran Team Assisted Individualization (TAI) dapat meningkatkan hasil belajar siswa kelas XII IPS-2 SMAN 3 Mataram Tahun Pelajaran 2022/2023 untuk komponen pengetahuan materi PDB, PDRB, PNB, PNN. Terjadi peningkatan nilai rata-rata siswa secara klasikal yaitu dari 68,02 pada Prasiklus menjadi 78,21 (Siklus I), dan meningkat lagi menjadi 86,64 (Siklus II). Terjadi peningkatan ketuntasan belajar secara klasikal yaitu dari 25,00 % pada Prasiklus menjadi 63,89 % (Siklus I), dan 86,11% (Siklus II).
HASHTAG AKTİVİZMİ ARAŞTIRMALARININ BIBLİYOMETRİK ANALİZİ
Authors: İLİ Burak , BÜYÜKBAYKAL Güven Necati 
Published: August 2023

HASHTAG AKTİVİZMİ ARAŞTIRMALARIN BİBLİYOMETRİK ANALİZİ

ÖZ
Tarihsel olarak marjinalize edilen topluluklar ve seslerini duyuramayan bireyler için sosyal medya, önemli bir etkileşim ve farkındalık imkânı sunmaktadır. Sosyal medyanın yaygın kullanımı, hemen her alanda olduğu gibi toplumsal hareketlerin ve aktivizm faaliyetlerinin yeniden şekillenmesinde de önemli rol oynamaktadır. Bu kapsamda ortaya çıkan hashtag aktivizmi, sosyal medya ağlarında hashtaglerin kullanımıyla gerçekleşen bir dijital aktivizm hareketi olarak dikkat çekmektedir.
Bu araştırma, uluslararası bir veri tabanı olarak dünya çapında kullanılan Scopus’ta yayınlanmış hashtag aktivizmine yönelik çalışmaların bibliyometrik analiz ile incelenerek, günümüzdeki ve gelecekteki eğilimleri ortayı çıkarmayı amaçlamaktadır. Bu kapsamda, 5 Haziran 2023 tarihinde ‘‘hashtag activism’’ terimi kullanılarak Scopus’ta bir inceleme gerçekleştirilmiş ve araştırma başlıklarında bulunması şeklinde sınırlandırılarak toplamda 72 akademik çalışmaya ulaşılmıştır. Hashtag aktivizmine yönelik araştırmalar, VOSviewer yazılımı kullanılarak yazarlar, yayın yılları, anahtar kelimeler, atıflar, ülkeler ve ortak yazarlık gibi farklı çerçevelerde incelenerek tablolaştırılmış ve görselleştirilmiştir. Elde edilen bulgulara göre, henüz yeni sayılabilecek bir kavram olan hashtag aktivizmine yönelik araştırmaların Scopus veri tabanında 2015 yılı itibarıyla yayınlandıkları, toplamda 72 araştırmanın genellikle ülke bazında gerçekleştirildiği, en çok yayın yapan ve atıf alan ülkenin Amerika Birleşik Devletleri olduğu ve hashtag aktivizminin en çok sosyal medya, feminizm ve Twitter anahtar kelimeleri ile birlikte kullanıldığı gibi sonuçlara ulaşılmıştır.

Anahtar Kelimeler: Hashtag Aktivizmi, Sosyal Medya, Toplumsal Hareketler, Bibliyometrik Analiz, Scopus, VOSviewer
Detection of defects in bulging processes by means of dynamic laser speckle
Authors: Jasiński Cezary , Morawiński Łukasz , Kocańda Andrzej 
Published: August 2023

The method described in this paper has been used to determine the moment when defects appear in the form of strain localization and grooves in the Marciniak bulging tests. In this method based on dynamic laser speckle, the sheet is illuminated by laser. Interference after reflection from the specimen surface creates a characteristic image of bright and dark spots. Specimen surface changes related with deformations and movements cause changes in the shape and size of spots, which are presented by authors in the form of speckle activity image. In order to identify the type of defect, the additional 3D microscopy measurements were performed. This paper presents analysis of the changes in the speckle activity image during the bulging process which enabled the defects identification during the bulging process.
Numerical determination of equiaxed grain radii arising in the casting during 3D simulation of solidification
Authors: Dyja Robert , Gawrońska Elżbieta , Grosser Andrzej , Jeruszka Piotr , Sczygiol Norbert 
Published: August 2023

The knowledge of material structure allows to predict the mechanical properties of alloy casting. Such structure can be modelled in micro- and mesoscale. The first way is connected with alloy morphology and enables one to find out the shape of grains emerging during the solidification process. The second way allows to define the magnitude and distribution of these grains in the casting structure. Learning both of these ways greatly enhances one’s knowledge about such mechanical phenomena as emerging stresses, strains, hot cracking and many others. This information makes it possible for one to predict the behaviour of castings during the cooling process or the further product exploitation. The one of the most difficult issues in the numerical and computer simulations of solidification is the modelling of the structure evolving in the casting. These simulations are extremely important in the work of an engineer in the foundry industry. The paper deals with a numerical modelling of equiaxed microstructure formation during the solidification of two-component alloys. The basic enthalpy formulation was applied to model the solidification. The equiaxed grain size depends on the average cooling velocity at the moment when the liquid metal reaches the liquidus temperature. The experimentally determined dependence between grain radius and cooling velocity was used in the calculation of average grain radii distribution.
Elaboration of ductile fracture criteria based on punching forgeability test
Authors: Lisiecki Łukasz , Skubisz Piotr 
Published: August 2023

A new approach of forgeability test, based on compression-punching state of stress was proposed. Comparison of the results of the presented research methodology with standard compression test is presented. The new forgeability test is designed to generate controllable failure location for good plasticity materials, which high the level of stresses accompanying the fracture. Different shape of tools and specimens tend to show the effect of geometry on the areas of concentrations of tensile and shear stresses, which play important role in formation of cracks. The paper presents the methodology based on laboratory tests of compression and pseudo-punching performed on laboratory rig with 5MN hydraulic press and numerical FEM simulation of the tests on commercial code with introduction of the elaborated fracture criteria.
Modelling of transient temperature field and phase transformation change a way for residual stress management in large size forgings
Authors: Sroka Jakub , Talamantes-Silva Jesus  , Krzyzanowski Michal  , Rainforth Mark  
Published: August 2023

The paper is devoted to development of the modelling approach based on 3D finite-element (FE) analysis of the transient temperature fields and the thermally induced phase transformations as a way towards residual stress management in large size forgings. Heating, holding and cooling stages are under consideration and modelling of both the austenite formation and decomposition are taken into account. The thermal-mechanical FE model capable of taking into account changes in the specific volume during ferrite/austenite transformation is coupled with the relevant phase transformation model in order to allow simulation of the transient stresses due to both thermal contraction and the dilatometric effect. The model is capable of taking into account different boundary conditions for the heat transfer problem based on the available data. To improve the predictive abilities, the following two commercial FE codes, such as MSC Marc 2013.1.0 and Abaqus/Standard6.12, are used for solving the non-steady state 3D problem of the metal expansion/contraction during consecutive heating, holding and cooling stages. Although all the mentioned process steps are considered, the model is dedicated to be used for modelling the cooling stages of large forgings and castings.
Using the System of Graph Grammar for generation of quasi optimal element partition trees in two dimensions
Authors: Paszyńska Anna  , Świderska Iwona  , Woźniak Maciej  , Jopek Konrad  , Paszyński Maciej  , Grabska Ewa  , Lenhart Andrew  , Nguyen Donals  , Pingali Keshav  
Published: August 2023

The paper presents a graph grammar based approach for h-adaptive finite element method and multi-frontal solver algorithm. The multi-frontal solver is used for solving systems of linear equations created by finite element method. The multi-frontal solver is controlled by so-called ordering. The quality of ordering influences hardly the solver effectiveness. In our approach, the finite element mesh is represented by means of a hypergraph and corresponding element partition tree. The finite element operations like mesh generation or h-adaptation are modelled by graph grammar production. Additionally graph grammar productions have corresponding productions for the construction of the element partition tree. The element partition trees are transformed into the ordering that controlls execution of the solver algorithm. We show that the ordering resulting from our element partititon tree results in better performance of the parallel solver than the state of the art nested-dissection ordering available through MUMPS interface on the class of grids refined towards singularities.
A parallelized model for coupled phase field and crystal plasticity simulation
Authors: Lin Mingxuan  , Prahl Ulrich  
Published: August 2023

The predictive simulation of materials with strong interaction between microstructural evolution and mechanical deformation requires the coupling of two or more multi-physics models. The coupling between phase-field method and various mechanical models have drawn growing interests. Here, we propose a coupled multi-phase-field and crystal plasticity model that respects the anisotropic mechanical behavior of crystalline materials. The difference of computational complexity and solver requirements between these models presents a challenging problem for coupling and parallelization. The proposed method enables parallel computation of both models using different numerical solvers with different time discretization. Finally two demonstrative examples are given with an application to the austenite-ferrite transformation in iron-based alloys.
Sensitivity analysis and identification of the phase transformation model based on the control theory
Authors: Milenin Ivan , Bzowski Krzysztof , Rauch Łukasz 
Published: August 2023

The aim of this work was to improve the previously developed model of austenite-ferrite phase transformation by its identification for selected steels and by performing sensitivity analysis. Created model allows prediction of phase transformation kinetics for non-isothermal conditions. Model is characterized by very short computing time and relatively good predictive capabilities. There are five input coefficients in the model, which should be identified for each steel on the basis of dilatometric tests. In the previous works model was used to predict phase transformation kinetics in various DP steels for different thermal cycles. In the first part of this work sensitivity analysis of the model was performed using three methods: quality method, factorial design method and Morris analysis method. Obtained sensitivity coefficients described how changes of the model input parameters influence the response of the model and which of these parameters are the most significant. The second part of the work was devoted to model identification for the selected steels. Identification problem was turned into optimization task which was solved using Hooke-Jeeves method. Obtained model’s parameters allowed describing austenite-ferrite phase transformation in the conditions of varying temperatures. Validation of the model was performed by comparison with the results obtained from the advances numerical model based on the solution of the diffusion equation in the austenite. Results obtain from both models for typical thermal cycled used to obtain multiphase microstructure were compared.
Numerical model of thin metal film heating using the boundary element method
Authors: Majchrzak Ewa  , Mochnacki Bohdan  
Published: August 2023

The subject of the paper is connected with the microscale heat transfer proceeding in the metal domain. In particular, the heating process of thin metal film subjected to an external heat flux is analysed. Thermal processes in the domain considered are described by the dual-phase lag equation (DPLE) supplemented by the appropriate boundary and initial conditions. At the stage of numerical modeling the variant of the boundary element method called the BEM using discretization in time is applied. So far, this method has not been used fo the hyperbolic equations describing the microscale heat transfer. In the final part the example of computations is shown.