bluuebunny/crossref_metadata_2025 huggingface dataset:
Analisa Kepuasan Pengguna Aplikasi Tiktok Menggunakan Metode End User Computing Satisfaction (EUCS)
Authors: Varahim Nur
Published: May 2024

Di era digital yang kita rasakan dewasa ini, sudah banyak sekali perkembangan yang terjadi disetiap tahunnya teruma di bidang teknoligi digital. Dengan perkembangan teknologi informasi yang pesat melahirkan temuan baru yang berdampak bagi masyakat saat ini. Kemudahan yang diberikan internet berhasil mengubah gaya hidup masyarakat saat ini. Bahkan dewasa ini penggunaan intenet tidak lagi sebatas media komunikasi melainkan sudah menjadi media promosi, media informasi, media hiburan dan masih banyak lagi. Salah satu aplikasi media hiburan yang diminati masyarakat saat ini adalah aplikasi tiktok. Suatu sistem informasi dikatakan berhasil jika informasi diproses hingga menghasilkan informasi yang baik, akan tetapi penerimaan kepuasan dan penerimaan pengguna terhadap sistem atau aplikasi juga menjadi salah satu tolak ukur kesuksesan dari sistem informasi tersebut. Penelitian ini bertujuan untuk mengetahui tingkat kepuasan pengguna aplikasi Tiktok dan factor-faktor apa saja yang mempengaruhi tingkat kepuasan pengguna. Penelitian in menggunakan metode kuantitati dan variable Content, accuracy, ease of use, dan timeliness. Teknik pengambilan sampel menggunakan metode purposive sampling. Proses analisis menggunakan pendekatan PLS-SEM dan aplikasi SmartPLS versi 4.0. hasil penelitian ini ada 1 hipotesis yang diterima yaitu content.
Simulation of the 2E Technique on neutron multiplicity measurement as a function of fragment mass in spontaneous fission of 252Cf
Authors: Montoya Modesto , Obregón A. , Alvarez M.
Published: May 2024

A Monte Carlo simulation algorithm to investigate the measurement of the average prompt neutron multiplicity as a function of pre-neutron mass, ν(A), for fragments from the spontaneous fission of 252Cf is presented. The input data consist of experimental measurements of the kinetic energy and mass distributions obtained by Göök et al., and the values of ν(A) calculated using the FIFRELIN model by Piau et al., νth(A). We analyze the output curve, νsim(A), obtained by simulation of the 2E technique, which should ideally match νth(A). However, we find that νsim(A) exhibits a maximum value at A≈122, close to mass symmetry, while νth(A) has a maximum at A≈118. Additionally, we observe that νsim(A) > νth(A) for A< 90 and A> 169, respectively. We attribute this discrepancy to inaccuracies in the relationship between provisional mass and the pre-neutron mass used in the 2E technique for data processing in each fission event.
Comparative study of alpha scattering from various nuclei at 130 MeV: Microscopic potentials and coupled channel calculations
Authors: Ibraheem Awad , Alasmary F. , Alshahrani B. , Karakoç M. , Hamada Sh. , El-Hammamy M. N.
Published: May 2024

The angular distributions of the elastic and inelastic scattering cross sections of alpha projectiles on different heavy ion target nuclei including 12C, 16O, 24Mg, 28Si and 40Ca at energy of 130 MeV have been studied using two different microscopic real potentials generated by the energy density functional (EDF) theory, and single folding cluster model as well as phenomenological Woods-Saxon potentials. A new parameterization was considered for the first time by EDF and to make the normalization coefficient tend to unity, it is necessary to consider correction to the calculated real potential. Coupled channel calculations for various low-lying states were performed, and the best fit values for the deformation length with the above models were extracted by fitting the inelastic scattering cross section and compared to previous work values. The total reaction cross section, as well as the real and imaginary volume integrals, have been studied.
Qualitative evaluation of a parabolic mirror with substructured Ronchi gratings
Authors: Campos-García Manuel , Granados-Agustín Fermín , Aguirre-Aguirre Daniel , Moreno-Oliva Víctor Iván , Huerta-Carranza Oliver
Published: May 2024

In this work we propose to qualitatively test the quality of a concave parabolic mirror by means of the Ronchi interferometric test using substructured gratings to increase the sharpness of the fringes. The substructured gratings are designed considering that the grating period is divided into several stripes of equal width that can be transparent or opaque; the transmission coefficients of the stripes along the grating period are not periodic, but a previously chosen binary sequence. Equations were derived to obtain the corresponding intensity profiles and an analysis of these profiles was performed for different sequences and positions of the substructured gratings with respect to the test mirror. It was experimentally verified that the fringes are sharper at the Rayleigh distance inside and outside the mirror focus.
Experimental validation of the appropriate channel model for an indoor Visible Light Communication system
Authors: Milena E. Premanath  , Nawanjana M. Pathirage  , Dilanka De Silva
Published: May 2024

Visible light communication (VLC) is a technology with significant potential to revolutionize indoor communication performance and satisfy the demands of fifth-generation (5G) and beyond technologies. To achieve an efficient VLC system that delivers optimal performance and coverage, it is imperative to create a reliable channel model. As a result, this research is centered around the evaluation of existing channel models for planning the VLC network coverage within indoor environments. The primary focus of this study is to enforce three types of channel models, Line of Sight (LoS), Nakagawa’s first reflection model, and the Spherical model through MATLAB simulations and obtain simulation results by varying the distance parameter. Furthermore, this research intends to implement a physical prototype representing a real-world scenario, and thereby determine the nearest channel model that aligns with the physical measurements obtained from the physical prototype.
Desafíos para jóvenes indígenas de Michoacán en el acceso a la educación superior
Authors: Ortiz Soriano Agustina
Published: May 2024

El objetivo de este trabajo es identificar los factores que obstaculizan el acceso a las instituciones de educación superior de los jóvenes indígenas de Michoacán. Para ello, se llevó a cabo un análisis documental con enfoque hermenéutico centrado en el tratamiento de la información disponible en sitiosoficiales gubernamentales, así como en textos especializados en el tema. La atención y cobertura de los servicios educativos de nivel superior es de reciente inclusión en el esquema de escolarización obligatoria del Estado mexicano (mayo de 2019), contenido en la fracción X del artículo 3º constitucional, pero queda adiscreción de las autoridades asegurar el acceso y la permanencia, asunto que sigue sin atenderse en las agendas políticas de los gobiernos estatales y locales, lo que lacera el derecho a la educación de los indígenas de Michoacán.
СКАРГИ НА ПЕДАГОГІВ ШКІЛ УРСР ДРУГОЇ ПОЛОВИНИ 1940–1980-Х РР. МОВОЮ АРХІВІВ
Authors: Лаврут Ольга Олександрівна
Published: May 2024

У роботі розглянуто скарги на вчительство Української РСР періоду другої половини 1940–1980-х років. Новизна дослідження полягає в аналізі змістового наповнення скарг, які стосувалися педагогів шкіл і механізму їх перевірки. Мета – з’ясувати обставини появи скарг на педагогів і процес їх розгляду. Реалізувати мету й виконати завдання допомагають аналітичний, хронологічний, конкретно-історичний метод. Висновки. Скарги, як правило, мали суб’єктивний характер і були спрямовані на дискредитацію педагогів. Сам процес був довготривалим, що було пов’язано з правилами ведення діловодної документації, бюрократією, перевірками фактів, що викладені в скаргах. Була ціла низка вказівок щодо реєстрації, адресності, розгляду справ, дотримання ведення їх вимог. Їх порушення вважалося неприпустимим. Обов’язковим елементом стало з’ясування суті справи, спілкування з педагогами, на яких скаржилися; із дітьми, які ставали свідками різних дій учителів або ж заперечували ці факти; із батьками, які виражали інтереси своїх дітей і могли теж спростувати або підтримати звинувачення. Інспектор, який приїздив у школу, відвідував уроки й позаурочні заходи, що проводили педагоги, спостерігав за їхньою діяльністю й комунікацією з колегами та школярами. Учителі писали пояснювальні записки, де показували власне бачення ситуації. Звертали увагу не лише на освіту, підвищення кваліфікації, професійність педагогів загалом, а й на особисті якості: порядність, активність, людяність, працьовитість. Первинні профспілки в школах також могли надати інформацію про власне бачення інцидентів. Тому, спілкуючись і спостерігаючи за учасниками освітнього процесу, створювалася загальна неупереджена картина, яка підтверджувала або спростовувала скарги на учителів. Педагогів розглядали не лише носіями власних професійних якостей, а й ретрансляторами провідних ідей влади. Вони мали поєднувати в собі багато функцій і реалізовувати гасла на практиці. Не дивно, що поведінку вчителів засуджували, обговорювали на різних зібраннях, долучаючи й громадськість. Радянський учитель мав бути провідником партійних планів, тому його образ мав залишатися ідеалізованим. Але це було не завжди. Педагоги залишалися насамперед людьми, які мали особисте життя, цінності, переконання й могли йти в розріз із суспільно регламентованими.
МУЗЕЄЗНАВЧІ СТУДІЇ ІЛАРІОНА СВЄНЦІЦЬКОГО (1905–1930-ТІ РР.)
Authors: Гаврилюк Світлана Віталіївна , Надольська Валентина Василівна
Published: May 2024

Мета статті – висвітлити музейну діяльність Іларіона Свєнціцького (1876–1956) упродовж 1905–1930-х рр. – ученого-лінгвіста, мистецтвознавця, громадського діяча, багаторічного директора Національного музею у Львові, заснованого в лютому 1905 р. греко-католицьким митрополитом Андреєм Шептицьким. Підкреслюється, що попри численні публікації, досі є потреба в аналізі музеєзнавчих напрацювань ученого. Розкрито теоретичну й практичну діяльність І. Свєнціцького в галузі музейництва, зокрема, схарактеризовано його наукові праці й виступи, у яких порушуються питання завдань музеїв, розкривається суть й основні етапи становлення музею як культурної установи, робиться огляд зарубіжних та українських музеїв, визначаються нагальні завдання Національного музею у Львові. Увага приділена організації І. Свєнціцьким виставкової й видавничої роботи в очолюваному ним музейному закладі. Зауважено, що І. Свєнціцький був пοпуляризатοрοм розвитку Національного музею у Львові, у щорічних звітах детально документував питання внутрішньої діяльності музею. У статті звернено увагу на заходи I. Свєнціцького з пошуку й вивчення пам’яток. З’ясовано, що науковець проводив активну науково-фондову роботу, систематично поповнюючи музейні збірки пам’ятками українського мистецтва та іншими реліквіями. I. Свєнціцький був активним членом громадської організації «Союз музеїв у Польщі», брав участь у з’їздах представників музеїв Польщі, докладав зусиль до діяльності музейних закладів у Галичині на високому професійному рівні. Доведено, що науковий доробок музейника залишається актуальним для вивчення історії, теорії й практики музейного будівництва в Галичині в першій третині ХХ ст.
РЕПЛІКИ ПЕРЕЩЕПИНСЬКОГО СКАРБУ В ЕКСПОЗИЦІЇ НАЦІОНАЛЬНОГО ІСТОРИЧНОГО МУЗЕЮ БОЛГАРІЇ ЯК ПРИКЛАД ВІДТВОРЕННЯ ТА МОДЕЛЮВАННЯ СТАРОВИННИХ АРТЕФАКТІВ В ЕКСПОЗИЦІЙНІЙ ДІЯЛЬНОСТІ МУЗЕЇВ
Authors: Сошніков Андрій Олександрович , Тортіка Марія Валеріївна
Published: May 2024

Мета статті – вивчити принципи введення реплік Перещепинського скарбу в експозицію ранньосередньовічної колекції Національного історичного музею Болгарії. Реквізит, бутафорія та репліки популярні у світі сучасного мистецтва. Якщо раніше їх використовували лише в театрі, кіно та рекламі, то сьогодні їх дедалі частіше замовляють музеї для своїх експозицій. Моделі та копії дають змогу експозиціонеру створювати візуальні образи оригіналів, які з певних причин не можуть бути задіяні як експонати. Точні копії з характеристиками реального об’єкта можуть бути зроблені як з реального предмета, так і з його зображення. Як до успішного прикладу звернемося до болгарського музейного досвіду застосування реплік в експозиційній діяльності. Зазначається, що Перещепинський скарб став основним археологічним доказом існування болгарської державності протягом 1300 років. Ці предмети працюють на ідею національної тяглості та величі болгарської державності. Автори статті вважають, що точне відтворення артефактів Перещепинського скарбу покликане емоційно вплинути на відвідувачів, адже таємнича історія знахідки скарбу, загадка його походження, багатство і розмаїтість перещепинського золота – усе це тримає відвідувачів у постійній зацікавленості розповіддю екскурсовода. Така організація експозиційного простору стала каталізатором подальшого комунікаційного зростання болгарської музейної мережі. В експозиціях почали широко використовувати копії, реконструкції, новоділи, муляжі та інші науково-допоміжні засоби. Розміри найбільшого історичного музею в Болгарії приваблюють дедалі більше відвідувачів, і, відповідно, пропонуються екскурсії різнопланового характеру. Так, НІМ реалізує свій музейний потенціал на максимально високому рівні, використовуючи історичні репліки як експозиційний матеріал.
Effect of Elementally Blended Ni-Ti and Pre-alloyed Nitinol Powders on Solidification Behaviour during Laser Bed Powder Fusion (L-PBF)
Authors: Bourke Declan , Selvam Karthikeyan , Obeidi Muhannad Ahmed , Ahad Inam Ul , Brabazon Dermot
Published: May 2024

Most research to date in the field of L-PBF of nitinol has been with near equiatomic nickel-titanium binary pre-alloyed powders. Significant understanding over the last 10 years has been gained in relation to aspects such as microstructural evolution, control of elemental composition, phase transformation behaviour, control of defects and mechanical properties. Challenges with the use of pre-alloyed nitinol powders include expense and time constraints in producing new blends. Elemental blending with in-situ alloying of nickel, titanium and other constituents at the point of additive manufacture offers the opportunity to significantly accelerate the pace of research of nitinol material and part geometry design. Other potential advantages of elementally blended over pre-alloyed powders include reduced process costs, energy savings, and improved control over final part macroscopic properties as well as local microscopic composition and properties. The relationship between elemental and pre-alloyed powder characteristics, the nitinol L-PBF process parameters and the resulting melt homogeneity has not previously been examined. This paper addresses this gap by examining, for in-situ alloyed nitinol, the relationship between laser power, scanning speed, powder properties and the resulting solidification track characteristics, and comparing results to those from pre-alloyed powder.
Processing Considerations of Nitinol Powders for LPBF
Authors: Coda Alberto , Lemke Jannis Nicolas
Published: May 2024

With the advancing progress in AM, there is a growing emphasis on powder manufacturing for reliable AM-built parts. Atomization technologies are well established for metal powder preparation, dominating the market for laser powder bed fusion (LPBF). They allow producing powders from a variety of metallic materials with high purity, adequate particles size distribution and without satellites.
Estimation of Residual Stress in Additive-Manufactured NiTi Alloy through Beam Mechanics and Finite Element Analysis
Authors: Rangaswamy Sampreet , Gillick Thomas , Monu Medad C.C. , Ahad Inam Ul , Brabazon Dermot
Published: May 2024

Due to the unique characteristics of nitinol (NiTi) such as shape memory and super-elasticity, it is widely utilized in various industries, particularly in aerospace and biomedical applications. Additive manufacturing technology can provide the accurate dimensioning of NiTi components, even for those with intricate and complex geometries. However, the presence of residual stresses poses a significant concern from additive manufacturing. These residual stresses can adversely impact the structural integrity and performance of the manufactured parts, necessitating careful consideration and management. This study delves into a distinctive approach for predicting residual stresses within additive manufactured NiTi components, employing a simple, non-destructive, and cost-efficient method that integrates beam mechanics equations with finite element analysis (FEA). This work aimed to develop a rapid and accurate method for measuring the residual stress from additively manufactured nitinol beams which will be validated via established techniques such as hole-drilling, XRD and/or neutron diffraction.
Manufacturing of Complex NiTi Geometries with LPBF and Adapted Scanning Strategies
Authors: Herzig Sandra , Eckert Medardus , Müller Bernhard , Weisheit Linda , Thielsch Juliane , Drossel Welf-Guntram , Holtzhausen Stefan , Koch Peter , Schleyer Mario
Published: May 2024

NiTi shows a very promising combination of properties among different shape memory alloys. However, machining NiTi is a challenging task, making the manufacturing of complex geometries hard to nearly impossible using conventional manufacturing routes. As a result, the material’s full potential of the material has not been harnessed. The pseudoelastic properties of bulk NiTi are restricted to an 8 % strain. Additive manufacturing of NiTi using laser powder bed fusion (LPBF) has been demonstrated as a successful alternative production route, capable of exhibiting pseudoelastic behavior even in the as-built state. Existing literature has shown that modifications of the processing parameters can change the properties of Ni-rich NiTi significantly, which can be utilized intentionally to control the pseudoelastic properties in LPBF-manufactured NiTi. The fabrication of porous and lattice structures using LPBF allows to attain specific properties. This is achieved not only through the adjustment of the laser parameters and scanning pattern but also by enabling the creation of specifically tailored feature sizes and geometrical designs, such as unit cell design, the number and distribution of unit cells, and gradation. These geometrical structures go beyond the conventional unit cell designs (like the bcc unit cell), and when combined with the unique material behavior, they can result in extraordinary properties. It is possible to create a programmable material whose behavior can follow a logical description. The influence of lattice structure geometry and manufacturing parameters on the mechanical and functional performance will be discussed in the following. In addition, we present a structure whose stiffness behavior follows an if-then-else statement regarding to the effective strain and permits an effective strain exceeding 20 % without failure. The structure can be implemented in a planar clamping element which allows an adjustment to different shapes because of the high and low stiffness in different strain ranges.
Investigating the Effect of Printing Process Parameters on the Shape Memory Effect of Nitinol Actuators
Authors: Murphy Josephine Ryan , Ahad Inam Ul , Brabazon Dermot
Published: May 2024

Nickel-titanium offers a promising alternative to traditional actuation devices due to its shape memory effect (SME) large strain recovery, and damping capability. Shape memory alloy actuators, thereby, offer a low-shock alternative to traditional pyrotechnic release devices used in spacecraft and satellites as well as energy-absorption components such as spacecraft landing systems. Additive manufacturing (AM) allows the production of complex geometries benefiting from their lightweight and compact nature. A prime example is lattice structures, with a geometrically defined porous structures featuring a repeating unit cell pattern or patterns in space. Beyond being lightweight, these structures offer high specific strength, excellent shock absorption, heat dissipation, and biocompatibility. By examining different process parameters, AM presents the possibility of tailoring nitinol’s properties while potentially removing the additional step of post-processing heat treatments conventionally required for shaping shape memory alloys. This approach has the potential to save time, cost, and energy.
Influence of the Flexible Interlayer on a 4D Printed Shape Memory Alloy Hybrid Composite
Authors: Kunzler Manuel , Kaiser Max , Gurka Martin
Published: May 2024

Active hybrid composites are gaining significance in various industrial and medical applications. These composites can include the integration of shape memory alloy (SMA) wires and fibre-reinforced plastics at material level and have the ability to undergo large deformations while activated. Typical applications are aerodynamic components such as car spoilers or wing profiles of an aircraft. Most applications often follow a partially integrated or modular shape memory alloy hybrid composite (SMAHC) design. In this paper, we pursue the approach of a fully integrated construction of an SMAHC. Therefore, we introduce two different designs of flexible interlayer of a 4D printed SMAHC by using the 3D stereolithography process. Achieving direct integration of SMA’s into plastic matrices requires the matrix material to possess adequate flexibility, as the SMA's thermal phase transformation process can accommodate elongation of up to 8%. Moreover, it is imperative to ensure that the process temperatures of the chosen manufacturing method remain below the austenite start temperature (As) to prevent inadvertent activation of the SMA during fabrication.
Additive Manufacturing of Cu-Al-Ni Shape Memory Alloys through Laser Powder Bed Fusion and Laser Metal Deposition: Challenges and Perspectives
Authors: Juan Jose M. San , Pérez-Cerrato Mikel , Del-Rio Lucia , Urionabarrenetxea Ernesto , Leunda Josu , Gómez-Cortés Jose F. , Aristizabal Miren , Quintana Iban , Carreño Fernando , Burgos Nerea , Nó Maria L.
Published: May 2024

Shape memory alloys (SMA) are functional materials that are being applied in practically all industries, from aerospace, automotive, robotics and biomedical sectors, and at present the scientific and technologic communities of SMA are looking to get the advantages offered by the new processing technologies of additive manufacturing (AM). However, the use of AM to produce functional materials, like SMA, constitutes a real challenge because of the particularly well controlled microstructure required to exhibit the functional property of shape memory. Most of the efforts are being focused on AM of Ti-Ni alloys, but there is a growing interest in Cu-based SMA due to their good functional properties of shape memory and superelasticity, even at high temperature. In the present work, the design of the complete AM processing route, from powder atomization and using two different methods of AM, is developed and the finally obtained thermomechanical properties are compared to those obtained by classical powder metallurgy route, using exactly the same Cu-Al-Ni SMA powders.
Sinter-Based Additive Manufacturing of Ni-Ti Shape Memory Alloy
Authors: Cohen Yeshurun , Addess Alon , Burkhardt Carlo , Vogel Lucas , Baum Andreas , Mitteramskogler Gerald , Glass Boaz , Rabkin Eugen , Shilo Doron , Faran Eilon
Published: May 2024

Additive manufacturing (AM) of Shape Memory Alloys (SMA) is an emerging technology that can open the route for numerous new applications in the fields of actuation, sensing, energy harvesting, and heat management. Currently, most AM processes of SMA rely on melting-based methods that locally melt the metallic feedstock of Ni-Ti. However, the repeated melting impairs the resulting microstructure, thus limiting the ability to undergo a reversible thermo-elastic martensitic transformation. Recent advances in sinter-based AM have the potential to facilitate the control over the final microstructure and properties of the printed SMA. Here, we present the production and characterization of Ni-Ti SMA produced via two sinter-based AM methods: 1. Lithography-based Metal Manufacturing (LMM), and 2. Moldjet, a unique modification of conventional metal injection molding.
Effect of Severe Torsion Deformation on Structure and Properties of NiTi Shape Memory Alloys
Authors: Komarov Victor
Published: May 2024

NiTi shape memory alloys (SMA) are attractive functional materials that are widely used in different fields of engineering and medicine for production of various shape-memory devices. The severe plastic deformation (SPD) is one of the most effective methods for the formation of an ultrafine-grained structure (UFG) in NiTi SMA, which is characterized by the best combination of functional properties. The development of SPD methods continues in the direction of the investigation of new approaches allowing to produce bulk samples with a nanocrystalline structure. Severe torsion deformation (STD) is a promising SPD method that allows for high plastic strain accumulation without significant dimensional changes. It was established that application of STD provides simultaneous improvement of strength and ductility of studied alloys. However, STD has never been applied to NiTi SMA. Therefore, in this study, STD was applied to NiTi SMA at various deformation temperatures from 350 to 600°C in order to maximize the number of turns and accumulate significant strain. Deformation in this temperature range leads to the formation of a dynamically polygonised dislocation substructure, that must provide conduction of the highest number of turns and facilitate the formation of an UFG structure. The goal of this work is to evaluate the possibility of applying the torsional deformation to bulk NiTi samples at low temperatures (in the range of dynamic polygonization) to accumulate high strains and refine the structure.
Influence of Heating, Cooling Rates, and Testing Media on Results of ASTM E3097 Testing Performed on NiTi Wire
Authors: Davis Jack , Wilson Todd
Published: May 2024

The ASTM E3097 standard for constant-force thermal cycling provides a useful framework for measuring properties of shape memory alloys relevant to actuation applications, namely transformation strains and transformation temperatures. The standard allows for operator discretion when selecting a heating and cooling rate for the thermal cycling, provided that the specimen temperature is maintained uniformly within ±3°C across the specimen throughout the course of the thermal cycling. With larger test specimens such as dog-bones, for example, this can be ensured via thermocouples affixed to the specimen. Substantial work has been done to quantify the ruggedness of the standard for such specimens. However, it can be difficult to verify specimen temperature in-situ during testing of wire specimens due to their small diameter. Contact methods, such as thermocouples, can be difficult to affix to the specimen due to its small size. It is also difficult to get accurate measurements using contact methods, due to the often- substantial size and mass disparity between the temperature sensor and the wire specimen and the tendency of the temperature sensor to act as a heat sink for the test specimen. Non-contact methods such as infrared (IR) thermography are possible, but not always practical. A high image resolution is crucial for IR measurement of small diameters, and calibration adjustments may be required from one test to the next, depending on surface characteristics and resulting emissive properties, to ensure accurate measurements. For these reasons, one common practice is to thermally cycle the wire specimens by means of a temperature-controlled environment, rather than heating the specimens directly, and change the temperature of the environment at a rate such that the wire specimen remains equilibrated in temperature. It is, therefore, especially important when testing wire according to the E3097 standard for the test operator to understand the potential influence of heating and cooling rates on test results. This work presents results from ASTM E3097 tests performed on various wire diameters using different thermal ramp rates, as well as different testing media.
Effects of Permanent Loads on Mechanical Performance of Nitinol Tubes
Authors: Guzmán José M. Matamoros , Sesin Jorge M. Cubero , Meza Fernando A. Dittel , Quirós Oscar Chaverri , Plaskonka-Weisenburger Katarzyna , Keck Andreas
Published: May 2024

Nitinol is frequently used as raw material for cardiovascular endoprosthesis, due to their high biocompatibility and properties such as psedoelasticity. Typically, the highest stress/strain that Nitinol based devices undergo occurs during crimping. These mechanical stresses can affect the functional fatigue behaviors. Nitinol devices are crimped to small diameters to deliver to the anatomical location of interest. Thereby, the microstructural and mechanical changes in Nitinol tubes generated by mechanical load conditions are studied, to monitor the pseudoelastic properties as a function of load time. Consequently, a permanent load test is carried out by means of a fixture with parallel clamps, in order to generate deformation of the cross-sectional area of the tube. The procedure consists of deforming 5 mm long samples with 7 mm outer diameter tubes and a wall thickness of 0.5 mm in straight annealed condition at room temperature. For this test, o-shaped samples of single ingot were analyzed. The test was carried out with strains of 2 %, 4 %, 6 % and 8 % to simulate different device crimp strains. Parts were evaluated after time intervals up to six months under load. Afterwards the geometrical changes of the samples were measured. Additionally, the samples were characterized by DSC and XRD measurements.
Observations of Damage and Crack Formation in Nitinol at Inclusions Smaller Than the Critical Flaw Size
Authors: Rendon Nathan , LePage William
Published: May 2024

Inclusions and surface defects are the primary drivers of fatigue fractures for Nitinol. Surface defects can take the form of die marks, surface roughness, or scratches, and when present, these will typically be the sites for fatigue fractures. When such surface defects are not present, however, surface-exposed inclusions become the primary sites of fatigue fractures. Surface-exposed inclusions are either fully embedded (no surrounding voids) or particle-void assemblies (PVAs). PVAs are up to 600 times more likely to be the sites of crack nucleation compared to fully embedded particles, so they are of primary interest. PVAs typically take the form of a single, small, and unbroken inclusion with one or two associated voids (coined a "teardrop"), or a longer, drawn-out, and broken-up inclusion with many voids (coined a "stringer").
Shape Memory Alloy Rotary Actuators for Aerospace: Part 2 Applications and Maturation
Authors: Calkins Frederick , Nicholson Douglas E. , Mabe James H.
Published: May 2024

Shape memory alloys (SMA) provide a compact, robust, light-weight and scalable rotary actuation technology suitable for many aerospace applications that require precise control and high torque over a discrete output range. With their compact form factor and high energy density, SMA rotary actuators can often be directly integrated into or near a hinge line reducing the need for complex kinematics (e.g., linkages and gears) that are typically required to transfer the work from a rotary actuator’s output to an effector such as a flap or aileron. Boeing has executed high technology readiness level (TRL) demonstrations and production use of scalable SMA rotary actuation technology across several size scales and aeronautical platforms. Applications range from wind tunnel models to full-scale laboratory demonstrators and flight tests. Successful demonstrations include reconfigurable vortex generators, actuated wind tunnel models, adaptive trailing edges, power door opening systems, spanwise adaptive wings, variable area nozzles and variable geometry structures.
Phase Transformation Temperatures and Pseudoelasticity Behavior of NiTi-X Ternary Shape Memory Alloys: A Molecular Dynamics Simulation Study
Authors: Bahramyan Mehran , Little Suzanne , Brabazon Dermot
Published: May 2024

NiTi alloy stands out as a promising material, particularly in biomedical, aerospace, and heat pump applications, owing to its biocompatibility and distinctive properties, including exceptional shape memory (SME) and pseudoelasticity. These properties arise from the alloy's capacity to undergo phase transformations during heating/cooling and loading/unloading cycles. The specific phase transformation temperatures and pseudoelastic behavior are heavily influenced by the composition of the alloy. The introduction of transition elements such as V, Cr, Mn, Fe, and Co in place of Ni and Ti can lower the martensite start (Ms) temperature, while substitution with Hf, Zr, Ag, and Au for Ni and Sc, Y, Hf, and Zr for Ti can elevate the Ms temperature. Consequently, it is imperative to comprehensively comprehend the effects of third alloying elements on the properties of these alloys from an atomic perspective. Molecular dynamics (MD) simulations, operating at the atomic level, offer a valuable means to explore the impact of various compositions, including the addition of a third element, on the alloy properties, thereby enhancing their performance. However, a significant challenge in MD simulations lies in selecting reliable interatomic potentials between the elements. Developing new potentials poses challenges, prompting the evaluation of existing potentials for ternary systems in this study, which will be compared with experimental results. While several interatomic potentials have been proposed for binary NiTi SMAs, limitations arise when extending to tertiary alloys. Existing studies have reported ternary interatomic potentials for NiTiV, NiTiNb, and NiTiHf, but these are insufficient for capturing the phase transformation of these tertiary systems. To address this, a hybrid model will be employed, combining different types of interatomic potentials such as modified embedded atom method (MEAM), embedded atom method (EAM), Lennard-Jones (LJ), and Morse potentials. This approach aims to capture the phase transformation of ternary alloys doped with elements like Cu, Hf, Pd, Pt, Sc, Ta, Mn, Zr, Y, and Au, which can increase transformation temperatures such as the martensite start temperature (Ms), martensite finish temperature (Mf), austenite start temperature (As) and Austenite finish temperature (Af), during cooling and heating processes. These alloys, known as high-temperature shape memory alloys (HT-SMAs), hold significant potential for diverse applications, including actuators, owing to their unique properties and enhanced transformation behaviours.
Modeling the Dynamic Deformation of Shape Memory Alloy Hybrid Composites under External Influences
Authors: Kaiser Max , Kunzler Manuel , Gurka Martin
Published: May 2024

Morphing shape memory alloy hybrid composites (SMAHC) offer a great potential for various engineering applications due to their lightweight properties and their ability to undergo significant deformations. They fundamentally consist of two primary components: a stiff substrate and a shape memory alloy (SMA) layer, enabling external two-way shape memory capability. During actuation the metallic SMA undergoes a contraction of several percent when subjected to electric current. As the SMA contracts, the substrate retains its original length, causing a bending movement in the composite. A third component to be mentioned is the interlayer, positioned between the rigid substrate and the SMA layer, opens up a greater design flexibility. By adjusting the distance between these two components fine-tuning of the relationship between deflection and bending moment in response to an external load can be achieved. (compare Fig. 1).
Nitinol Film: From Research to Clinical Trial
Authors: Miranda Rodrigo Lima de , Bechtold Christoph , Chluba Christoph
Published: May 2024

Nitinol, a remarkable alloy of nickel and titanium renowned for its unique shape memory and superelastic properties, has been instrumental in various industries for decades. Traditional fabrication methods, such as melting, metal transformation, and subtractive structuring, have been the norm in Nitinol production. The potential of alternative, additive deposition techniques, despite their precision and scalability, remains largely untapped in the manufacturing of Nitinol components, particularly those intended for clinical applications.
New Cu-Based Shape Memory Alloy Family Transforming at Ultra-Low Temperatures for Cryogenic Applications
Authors: Juan José M. San , Lorenzo Patricia , Nó Maria L.
Published: May 2024

Nowadays, there is a great interest in developing new families of shape memory alloys (SMA) exhibiting thermomechanical properties beyond the classical ones obtained with the well-known NiTi SMA and the derived ternary alloys. Indeed, a great effort is being focused in developing high-temperature SMA, like the ones based on NiTiHf/Zr or on Cu-Al-Ni, and also on the development of SMA that could be successfully implemented at micro and nanoscale for smart micro electro-mechanical systems (MEMS) applications. However, new hydrogen-based energy sources, high-power nuclear fusion and the emerging quantum computing technologies, as well as the classical superconducting ones, require low-temperature working environments. All of them need the use of sensors and actuators at cryogenic temperatures, but, at present, there are not shape memory alloys (SMA) offering the possibility of operating as sensors and actuators, valves for instance, at so low temperatures, below liquid nitrogen.
Alloy Design for Additive Manufacturing of Shape Memory Alloys
Authors: Pourshams Mohammad , Dabbaghi Hediyeh , Poorganji Behrang , Elahinia Mohammad
Published: May 2024

There is a growing need to design tailored alloys for Additive Manufacturing (AM) in order to achieve the desired properties and quality in the resulting parts. The need is even stronger for functional materials such as Nickel- Titanium (NiTi) shape memory alloys (SMAs) with microstructure-driven properties such as superelasticity and the shape memory effect. These alloys have been used in innovative applications in aerospace, biomedical, and robotics. Despite their potential, the realization of NiTi SMAs through AM faces significant challenges, including phase stability, compositional heterogeneity, and solidification defects, which impede the achievement of desired microstructural and mechanical characteristics.
Shape Memory Alloy Design for a Lightweight and Low Stow Volume Expandable Solar Concentrator
Authors: Worrell Dominique , Gantz Faith , Bolisay Linden , Palisoc Art , Young Marcus L.
Published: May 2024

Solar concentrators increase the amount of usable energy available in solar collection systems by focusing energy through an aperture to which energy is magnified within the area of its trajectory. Design challenges of a solar concentrators for space applications are to make them more lightweight, compact, and exhibit a smooth and consistent reflective surface curvature for optimal performance. Shape memory alloys (SMAs) offer an effective and compact solution to engineering needs, such as solar reflectors, to reduce weight and improve overall energy collection and concentration performance. The one-way shape memory effect can be used for this application, where the SMA is heat treated in a strained designed curvature by forcing the austenite microstructure to “remember” the original shape even after deformation. SMAs are capable of actuating from the stow configuration and into the designed shape after the solar energy exposure induces a phase transformation. In this study, NiTi and NiTiCu SMAs were thermomechanically processed into plates and cut into three sizes of triangular chips for use as reflector components. Standard binary NiTi SMAs was modified with the substitution of Cu for Ni to achieve a narrower hysteresis and better thermomechanical cycling stability. The SMAs were produced from commercially available NiTi SM495 plates by ATI Specialty Alloys and Components (Albany, OR) and custom-melted NiTiCu buttons. Each processing step was comprehensively characterized to monitor microstructural and thermomechanical property changes using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Vickers hardness (HV). The NiTi and NiTiCu triangular chips were shape-set utilizing a custom-made apparatus to attain the intended curved surface with specific dimensions for a reflector component within a solar concentrator.
Processing and Thermomechanical Stability of Low Hysteresis Shape Memory Alloys
Authors: Montagnoli Andre , Young Marcus L. , Somsen Christoph , Frenzel Jan A. , Calkins F. Tad , Nicholson Douglas E.
Published: May 2024

NiTi shape memory alloy (SMA) actuators have gained much attention in recent years because of their ability to combine high actuation forces to a significantly smaller component size. Binary SMAs containing Ni and Ti, however, suffer from relatively poor functional and structural fatigue, which requires training. Binary NiTi SMAs also possess a relatively wide hysteresis gap between the austenite final and martensite final temperatures (ΔTMfAf), which demands more energy to produce each actuation stroke. Zarnetta et al. have shown that small additions of substitutional elements to the NiTi-based SMA can significantly improve those conditions by increasing the coherency between the two transforming crystal structures. Two quaternary NiTiCuPd SMAs were selected based on combinatorial studies from X-ray diffraction data and their results were analyzed concerning their hysteresis width and thermal-mechanical stability.
Laser-Induced Nanostructures on Shape Memory Actuators for Strain Detection
Authors: Marx Jan , Schuleit Marvin , Haske Damian , Esen Cemal , Ostendorf Andreas
Published: May 2024

The activation behavior of nitinol actuators is typically examined in test rigs equipped with sensors for measuring mechanical and electrical parameters. However, these test rigs allow for measurements only under laboratory conditions; assessing the actuator behavior in real-world applications is not feasible. Therefore, a non-invasive, optical measurement method for relative strain detection of shape memory actuators is presented in this work. It is based on the diffraction of a laser beam by an optical grating applied to the surface of the actuator. While the grating period changes with the strain state of the actuator during activation, a camera captures the interference pattern to detect the diffraction angle of the maxima spots.
Atomic Layer Deposition as an Alternative Surface Finishing Technique: Characterisation of Oxide Layer Composition and Corrosion Behaviour
Authors: Höger Kim , Bruchlos Kirsten , Zende Stefan , Feth Nils-Agne
Published: May 2024

Nitinol is an important material for medical implants due to its super elastic behaviour and since its mechanical properties mimic biological materials. The surface of nitinol implants is commonly covered with a thin titanium dioxide (TiO2) layer which acts both as a passivating layer to increase the corrosion resistance and as a barrier layer to address the toxicological concerns of long-term nickel release into the biological tissue. Even though nitinol undergoes a natural passivation when exposed to air, various thermal, chemical, and electrochemical surface finishing techniques are applied during manufacturing to replace the native oxide layer by uniform TiO2 layers of controlled thickness. The properties of these oxide layers depend on the surface finishing technique and the process parameters.
Surface Functionalization of Nitinol Utilizing Ultrashort Laser Pulses
Authors: Bittigkoffer Lucas , Roth Henry , Baumann Martin , Feth Nils-Agne
Published: May 2024

Ultrashort pulse (USP) lasers are an established technology to manufacture nitinol medical devices. USP lasers offer a great variety of processing parameters which can be utilized for fine cutting, laser lathe and ablation of nitinol. Usually, several hundreds of kHz are used to penetrate the material with pulses of fixed energy and frequency. New USP laser sources are offering a so-called burst mode which can be used to precisely control the energy deposition into the material by adjusting the temporal pulse distribution. Depending on the applied process parameters, this leads to a cut through or ablation of some material besides a modification of the irradiated surface. Previous work showed that the bulk material is not affected by such laser light whereas the laser-matter interface is changed. The perpendicular irradiated surfaces are dominated by laser-induced periodic surface structures (LIPSS) which are oriented to the direction of polarization of the laser beam and by cone-like protrusions (CLPs). These modified surfaces allow, e.g., different roughness, wetting, corrosion, bioactivity, and ultimately tribological properties. The effect of such femtosecond laser-generated structures was shown for stainless steel and titanium. Complex medical devices might benefit from locally adjusted surface properties e.g. reduced frictional force between tissue and device or improved adhesion due to an increased surface area through microstructures.
OS FUNDAMENTOS DA NEUROAPRENDIZAGEM ATRELADOS ÀS TECNOLOGIAS
Authors: Souza Jadilson
Published: May 2024

Em decorrência dos avanços tecnológicos, várias possibilidades metodológicas de aprendizagem ganharam impulso no campo educacional, o que se tornou terreno fértil para investigação. É nessa problemática que emerge o objetivo norteador deste trabalho, pois, em seu bojo, residem chances de se mensurar e compreender algumas contribuições da Neuroaprendizagem associadas aos recursos tecnológicos como indicadores para o processo de ensino-aprendizagem. A Neuroaprendizagem abre caminhos para o entendimento dos processos cognitivos. A princípio, foi feita uma análise sobre os fundamentos da Neuroaprendizagem atrelada ao uso das tecnologias, especificamente no contexto formativo dos discentes. Além do mais, foram abordados aspectos de como é possível a viabilização do ensino-aprendizagem na cibercultura por meio dos recursos digitais como as imagens (midiática e representativa). Para tanto, a pesquisa assumiu caráter exploratório e, metodologicamente, configurou-se como uma pesquisa qualitativa, apoiada em pesquisa  bibliográfica, tendo como suporte teórico autores que contribuíram com essa linha de pesquisa. Os dados produzidos a partir das contribuições bibliográfica, através dos quais se permitiu concluir que a Neuroaprendizagem atrelada a tecnologias é meio que pode auxiliar a aprendizagem significativa, mas se faz necessário planejamento cuidadoso para propiciar métodos que dinamizem o aprender.
PRÁTICAS INTERDISCIPLINARES DE ENSINO DE CIÊNCIAS NA ESCOLA: ANÁLISE DE CONTRIBUIÇÕES DAS DISCIPLINAS DE EDUCAÇÃO FÍSICA E SOCIOLOGIA NA APRENDIZAGEM DO SISTEMA OSTEOMUSCULAR
Authors: Soares Lemos Shaw Gisele , Santos de Souza Ana Flávia , Luz Moura Diego , Soares Lemos Shaw Gisele
Published: May 2024

Neste texto, considerando as potencialidades de práticas interdisciplinares para o ensino, investigaram-se, qualitativamente, contribuições de uma sequência didática interdisciplinar para a aprendizagem de estudantes de uma turma de Educação de Jovens e Adultos (EJA) de escola pública sobre Sistema osteomuscular humano. Essa proposta foi discutida, colaborativamente, por professora formadora, professores da escola e estudantes de licenciatura em período de residência pedagógica e envolveu a inter-relação das disciplinas Ciências, Biologia, Educação Física, Física e Sociologia. A produção de dados consistiu em um relato escrito de licencianda que estava em exercendo residência pedagógica junto à referida turma e um questionário com questões abertas aplicado por ela, no início e ao final da intervenção. Os dados foram analisados através da análise de conteúdo de Bardin (1977). Os participantes demonstraram aquisição de conhecimentos sobre funcionamento da composição do sistema osteomuscular, além de reflexões sobre suas relações com a utilização de anabolizantes, noção de corpo ideal e função do alongamento estático antes da atividade física.