Smart Materials

Despite many important applications of α‐Fe2O3 and Fe doped SnO2 in semiconductors, catalysis, sensors, clinical diagnosis and treatments, one fundamental issue that is crucial to these applications remains theoretically equivocal—the reversible carrier‐type transition between n‐ and p‐type conductivities during gas‐sensing operations. Herein, we present an unambiguous and rigorous theoretical analysis in order to explain why and how the oxygen vacancies affect the n‐type semiconductors α‐Fe2O3 and Fe‐doped SnO2, in which they are both electronically and chemically transformed into a p‐type semiconductor. Furthermore, this reversible transition also occurs on the oxide surfaces during gas‐sensing operation due to physisorbed gas molecules (without any chemical reaction). We make use of the ionization energy theory and its renormalized ionic displacement polarizability functional to reclassify, generalize and explain the concept of carrier‐type transition in solids, and during gas‐se...

Microfluidic systems allow (bio)chemical processes to be miniaturized with the benefit of shorter time-to-result, parallelism, reduced sample consumption, laminar flow, and increased control and efficiency. However, such miniaturization inherently limits the size of the solid objects that can be processed and entails new challenges such as the interfacing of macroscopic samples with microscopic conduits. Here, we report a microfluidic probe (MFP) that overcomes these problems by combining the concepts of 'microfluidics' and of 'scanning probes'. Here, liquid boundaries formed by hydrodynamic forces underneath the MFP confine a flow of processing solution and replace the solid walls of closed microchannels. The MFP is therefore mobile and can be used to process large surfaces and objects by scanning across them. We illustrate the versatility of this concept with several examples including protein microarraying, complex gradient-formation, multiphase laminar-flow patterning, erasing, localized staining of cells and the contact-free detachment of a single cell. Many constraints imposed by the monolithic construction of microfluidic channels can now be circumvented using an MFP, opening up new avenues for microfluidic processing.

In this work the potential of employing electrophoretic deposition (EPD) for fabricating Li-ion battery electrodes without using binders and in particular eliminating volatile and toxic organic solvents such as n-methyl 2-pyrrolidone (NMP) is demonstrated. The paper in particular describes the successful application of the EPD method to fabrication of thick (>20 μm) nano-TiO 2 /carbon Li-ion intercalation anodes. The EPD system involves deposition of commercial P25 TiO 2 nanoparticles and carbon black on aluminum foil from an isopropanol bath without making use of charging agents or other additives. Hetero-coagulation of TiO 2 and C particles in the isopropanol medium enabled their 80 V DC cathodic deposition into a well-adhered film with effective intermixing of active and conductive components. Electrochemical testing of the newly binder-free EPD-built electrodes revealed comparable film conductivity, polarization and charge storage capacity properties with the standard binder-based PVDF/NMP electrodes. Most importantly, the charge storage, cycling, and rate properties of the EPD-built electrodes were greatly enhanced by post-EPD sintering of the film at 450 • C. The combined EPD-sintering route resulted in a superior conductive percolating network by promoting nanoscale film composition uniformity, inter-particle necking, and favorable porous structure for enhanced interfacing with the liquid electrolyte. The sintered EPD-built electrode exhibited almost 50% higher capacity retention than that of the standard binder-based electrode upon cycling. EPD with its inherent self-assembling functionality and its overall operational simplicity provides an advantageous and green Li-ion electrode fabrication alternative.

National audienceIonic electro-active polymers (EAP) are able to deform under the action of an electric field, which confers them many applications as sensor, actuator or energy recovery.An ionic metal-polymer composite (IPMC) consists in an ionic polymer film coated on both sides with a thin layer of metallic electrodes. The polymer is saturated with water, which results in its quasi complete dissociation : negative ions remain bound to the polymer backbone, which can be considered as a porous medium, and small cations are released in water. When an electric field orthogonal to the strip is applied, the cations move towards the negative electrode and carry solvent away by osmosis, causing the bending of the strip.We had previously established the conservation laws and the constitutive equations of this material. This model has been applied to the case of a cantilevered EAP strip subjected to a continuous voltage between its two faces (static case). Since the amplitude of the bendin...

The emerging field of spintronics explores the many possibilities offered by the prospect of using the spin of the electrons for fast, nanosized electronic devices. The effect of magnetization acting on a current is the essence of giant or tunnel magnetoresistance. Although such spintronics effects already find technological applications, much of the underlying physics remains to be explored. The aim of this article is to demonstrate the importance of spin mixing in metallic nanostructures. Here we show that magnetic clusters embedded in a metallic matrix exhibit a giant magnetic response of more than 500% at low temperature, using a recently developed thermoelectric measurement. This method eliminates the dominating resistivity component of the magnetic response and thus reveals an intrinsic spin-dependent process: the conduction-electron spin precession about the exchange field as the electron crosses the clusters, giving rise to a spin-mixing mechanism with strong field dependence.

In the past two decades, energy consumption worldwide has increased by more than 30%. In hot weather countries where temperature reaches high levels, thermal insulation materials have recently been highly considered due to their low thermal conductivity. This results in a substantial reduction in the demand for energy in building HVAC systems and its related negative impacts on the surrounding environment. The aim of this study is to determine the optimum construction technique used in buildings to enable energy saving with minimal occupation of space. This research focused on the role of wall and roof materials on the energy efficiency of a building. The research adopted mathematical calculations for finding the U-value of wall and roof insulating materials. The results showed that the cavity walls with insulation material and the cavity roof with air gap and insulation material are optimum solutions to be used in buildings. This study recommended considering long-term energy savings to substantiate the effectiveness of these materials in conserving energy for buildings.

In last two decades, energy consumption worldwide has increased by more than 30%. The limited thermal conductivity of thermal insulation materials is currently receiving significant attention in hot-weather countries where temperatures reach high levels. This leads to a significant decrease in the demand for energy in HVAC systems and reduces the negative effects on the environment. The purpose of current study is to define the optimum construction techniques for buildings to enable energy savings while occupying minimal space. This research dedicated on the role of wall and roof materials in the energy efficiency of a building by exploring different options, including variations in materials and construction methods. The study employed mathematical calculations to determine the U-value of wall and roof insulating materials. The results indicated that cavity walls with insulation material and cavity roofs with an air gap and insulation material are optimal solutions for improving energy efficiency in buildings. This study recommended considering long-term energy savings to substantiate the effectiveness of these materials in conserving energy for buildings.

The work studied the assessment of online education problems during the COVID-19 pandemic by the first year master’s students. It was hypothesized that there are two types of problems. The first type is the problems associated with the difficulties of online communication between the participants of the educational process. The second type is the problems associated with the technical difficulties of participating in online education. The results of factor analysis show that masters clearly distinguish between the content-related (online communication) and formal (technical problems) sides of the organization of online education. It was found that those masters’ students who do not work now or do not have work experience in the specialty for which they are studying generally perceive the presence of technical problems and Internet disruptions as difficulties in implementing online education more significantly.

Innovative communication systems based on advancement of the nanotube titanium (CNT-Ti) composites-based antennas are still difficult to design and optimize their performance, so the design could ultimately be crucial in development of these antennas. It is on this basis that the performance of these CNT-Ti CNT based composite antennas in the likely application in future wireless communication of the 6G networks was evaluated. The one that was shown by these antennas was high efficiency, large bandwidth, great flexibility, and enhanced attributes of improvement of impedance, which are appropriate in 6G wireless networks and high-speed communication. Besides, the analyzed CNT Ti composite-based antennas demonstrated a high conductivity, low loss tangent, low energy loss, high signal effectiveness, high bandwidth and low VSWR levels in comparison to conventional antennas. The proposed antennas with special directional patterns that are popular like the satellite communication might be constrained in the volume of their usage, however, with their large size and its expensive design. It was concluded that the enhancement of manufacturing process, price, design, scalability, and long-term reliability of the proposed antennas as the implementation in the large-scale technology of wireless networks should be the subject of the further studies allowing the sustainable expansion.

Composite materials based on NiFe 2 O 4 nanoparticles and polyethylene matrix have been synthesized by thermal decomposition to expand the application area of high-pressure polyethylene by filling it with nanoscale particles. The synthesized compositions were obtained in the form of a dark gray powder and compressed for further study According to TEM, the average particle size in composites was 2, 3, and 4 nm in samples with a filling of 10%, 20% and 30%. The concentration dependences of the specific electrical resistivity ρ V , dielectric permittivity ε, saturation magnetization M S and the parameters of reflection and attenuation of microwave power of the obtained composites were investigated. The threshold for percolation in such materials is found to be within a concentration range of 20.. .30%. The electronic and atomic structure of composites was studied by methods of Mössbauer spectroscopy, X-ray diffraction and X-ray absorption spectroscopy. The closest atomic environment of nickel and iron in nanoparticles is close to that of crystalline NiFe 2 O 4. The dependence of the nanoparticles size as well as the dependence of the number of tetrahedral or octahedral iron positions in nickel ferrite nanoparticles to their content in polyethylene matrix is established. It is shown that composite materials based on NiFe 2 O 4 nanoparticles and polyethylene matrix can be used as components of electromagnetic compatibility systems.

The problem of shape control and correction of small displacements in composite structures using piezoelectric actuators glued or embedded was addressed. A finite element model based on Mindlin plate theory was used to characterize the behaviour of the structure and the one of the actuators. Emphasis was put on the development of an efficient and general methodology, based on genetic algorithms, for the determination of the optimal actuation voltages needed to apply to the piezoelectric actuators in such a way that a pre-defined shape of the structure is achieved. The model was investigated numerically and verified experimentally. Measurements were carried out using electronic speckle pattern interferometry. Good agreement was found between simulation results and the optically measured values.

Widespread application of solar-driven hydrogen production is hampered by two major challenges: the safety risks associated with high-pressure H 2 storage and transport, and the intermittent nature of solar energy. Inspired by the natural spatial and temporal separation of light and dark reactions in photosynthesis, the emerging strategy of dark photocatalysis aims to separate the collection and conversion of solar energy. In the past few years, encouraging progress has been made in the dark photocatalytic production of hydrogen. Therefore, we summarize the advances in this field over the past few years. This review first discusses various charge storage mechanisms in depth. Then, a comprehensive review of key material systems is conducted, covering carbon-nitrogen-based materials, metal-organic frameworks, polyoxometalate-based materials, two-dimensional layered materials, as well as heterojunction/interface engineering and the combination of semiconductors with polyoxometalates. Furthermore, the performance of photo-charging and dark hydrogen evolution is analyzed in detail. Finally, we look forward to the future development direction of this field. This review aims to offer valuable insights and guidance for the design of efficient and stable dark photocatalytic materials.

The rising global demand for renewable energy highlights the urgency of developing compact, cost-effective, and sustainable solutions. This study introduces a piezoelectric wheel system designed to convert rotational mechanical energy into electrical energy, focusing on small-scale applications suitable for educational institutions, DIY innovations, and low-power devices. The prototype integrates 60 piezoelectric discs (27–35 mm) mounted on a bicycle rim, with 28–30 AWG stranded copper wires connecting the discs to a bridge rectifier and a rechargeable battery for energy storage. Experimental evaluation was conducted in a controlled laboratory environment in Angeles, Pampanga, employing rigorous quantitative methods. Voltage output was measured at rotational speeds from 10 km/h to 15 km/h using a calibrated digital multimeter, while the wheel’s durability and operational stability were assessed through a five-hour test, examining voltage and current consistency, disc adhesion, and tire pressure. Data were systematically collected with multiple trials ensuring reliability and analyzed using descriptive statistics, including mean, standard deviation, and percentage comparisons. Comparative analysis with solar and hydroelectric systems evaluated the energy conversion efficiency and practical viability of the piezoelectric wheel. Findings reveal a proportional increase in voltage output with rotational speed and sustained stability under prolonged operation, confirming the prototype’s effectiveness as a supplemental energy source. This research demonstrates the potential of small-scale, motion-driven piezoelectric devices to provide localized, renewable electricity while fostering hands-on learning and environmental awareness. It further contributes to the field by offering a replicable experimental framework, precise measurement techniques, and an empirically validated approach for decentralized energy harvesting.

The rapid expansion of the Internet of Things (IoT) has created a strong demand for sustainable, reliable, and maintenance-free power sources for distributed sensor nodes. Traditional battery-powered IoT systems suffer from limited lifetime, frequent replacement requirements, high maintenance costs, scalability limitations, and environmental concerns. Energy harvesting provides an attractive alternative by converting ambient sources such as mechanical vibrations, thermal gradients, and radiofrequency (RF) signals into usable electrical energy. This paper reviews key energy harvesting methods for self-powered IoT devices, including vibration-based, thermal, and RF harvesting, and discusses their operating principles, limitations, and application suitability. Since no single source can provide continuous power reliably under all conditions, multi-source and hybrid harvesting architectures are examined to improve reliability and energy availability. The review also highlights power management strategies, energy storage, and integration with ultra-low-power electronics as critical factors for autonomous operation. Adaptive duty-cycling, efficient power management, and co-design of harvesters and electronics are identified as essential for synchronizing device operation with fluctuating harvested energy. These approaches are key enablers for scalable and sustainable future IoT systems.

MASV-MUSCLE-C1-искусственный модальный актюатор нового типа Юридический статус • Авторство • Стандарт Настоящая работа является частью архитектурного корпуса MASV-Prime (Modal Analysis of the Structure of the Universe)-самодостаточной модальной системы, формирующей единый инженерный и теоретический аппарат описания структуры реальности. Автором и единственным правообладателем архитектуры MASV-Prime, включая её онтологию, математический корпус, систему операторов, константы, определения и все производные материалы, является Волынец Евгений Вацлавович (Республика Казахстан, город Костанай, дата рождения: 7 ноября 1981 года). Настоящая публикация имеет статус нормативного научно-инженерного документа и опирается на базовый стандарт: MASV-Prime Standard v1.0 (DOI: https://doi.org/10.5281/zenodo.18522304), определяющий фундаментальную модальную архитектуру, структуру поля φ, типы мод (S, F, FG), а также принципы фазовой геометрии и причинности Все положения, формулы, операторы и конструкции, представленные в данной работе, являются частью единого авторского корпуса MASV-Prime и рассматриваются как целостная интеллектуальная система, не имеющая внешних заимствований и не основанная на иных теоретических моделях. Публикация и все входящие в неё материалы охраняются международным авторским правом и нормами Бернской конвенции. © Волынец Евгений Вацлавович, 2026. Все права защищены Любое воспроизведение, распространение, адаптация, инженерное применение, включение в вычислительные системы, алгоритмы, модели или коммерческие разработки допускается исключительно при наличии письменного разрешения автора. Присвоение, модификация или использование архитектуры MASV-Prime без указания авторства квалифицируется как нарушение авторского права и интеллектуальной собственности. После публикации с присвоением цифрового идентификатора DOI документ приобретает статус международно зафиксированного научного источника, обеспечивающего неизменяемость версии и юридическую фиксацию авторства

The photoelectron spectra of mass-selected negatively charged Ni n 2 and Cu n 2 clusters show similarities, which indicate an almost total localization of the Ni 3d orbitals corresponding to a maximum magnetic moment of 1m B per Ni atom. The similarity between Ni n 2 and Cu n 2 vanishes for n . 7 corresponding to an increase in 3d delocalization. The data of Pd n 2 clusters suggest a Ni-like ("magnetic") electronic structure for n 3-6 and a Pt-like ("nonmagnetic") one for n . 15. There are indications that neutral Pd 7 is a closed shell species (spin zero ground state).

In this study, pristine and Fe-doped ZnO nanostructures (2-6 vol% Fe) were synthesized via the co-precipitation method and labelled as Zn@2Fe, Zn@4Fe, and Zn@6Fe. XRD analysis confirmed the formation of polycrystalline ZnO with a hexagonal wurtzite structure. FESEM and HRTEM revealed well-defined, uniformly distributed hexagonal nanorods, which exhibited superior crystallinity and surface morphology. FTIR confirmed the effective integration of Fe 3+ into the ZnO crystal lattice, while UV-Vis spectroscopy showed a blueshift and band gap widening from 3.41 eV (pure ZnO) to 3.16 eV (Zn@2Fe). BET analysis indicated increased surface area and porosity upon Fe doping, enhancing gas adsorption capacity. Among the samples, Zn@2Fe exhibited the best NO 2 sensing performance, with a maximum response of 6.5 at 180 °C, demonstrating good selectivity, stability, and rapid response-recovery time. The sensor showed a linear response over the 1-20 ppm NO 2 range and maintained consistent performance across multiple cycles. The enhanced sensing properties are attributed to increased surface reactivity, the formation of oxygen vacancies, and Fe 3+ /Fe 2+ redox interactions. These results establish Zn@2Fe as a promising material for high-performance NO 2 gas sensors.

This paper discusses the development of integrated design-to-production frameworks for Robotic Concrete 3D Printing (RC3DP) of context-specific urban furniture projects. The study focuses on two main objectives: developing computational methods for continuous toolpath planning of bespoke components and examining integrated frameworks to make design-to-production systems more socio-environmentally inclusive and
tailored to specific contexts. Following an introduction to outline the key challenges of continuous robotic concrete 3D printing, the paper is organized into two sets of case studies. The first set explores curved-based continuous 3D printing for surface-based design strategies, and the second set investigates voxel-based approaches for volumetric design 3D printing. Curve-based projects consisted of three case studies. The first case uses an AIenabled generative system to translate a porous, cellular structure to a continuous toolpath with variable heights.
The second case study is based on a workflow using a controlled reaction-diffusion algorithm as a generative strategy to create continuous infill for complex geometries. The third project focuses on growing larger than the size of the production setup by testing the assembly of multiple printed components, all produced with continuous toolpaths. The workflows and projects are developed as an integral part of a graduate-level digital design and fabrication course focusing on inclusive automation and robotic concrete 3D printing. Therefore, in addition to sharing the details of the developed computational design to production methodologies, the paper discusses the research findings from pedagogical lenses. Building on these cases, the investigation advances to the development
of a generative system centered on voxels, employing a tetrahedron structure. This volumetric approach simultaneously produces external surface tectonics and internal infill through a seamless toolpath. The paper concludes by presenting sets of guidelines and future directions for both the introduced curve and voxel-based approaches in Robotic Concrete 3D printing, emphasizing the early integration of computational and fabrication intelligence into the design process.

The characteristics of a new wave power generating system have been proposed by installing a piezoelectric sensor to the seaward position of an existing coastal structure. By installing the sensor to the structure, waves will hit the piezoelectric sensor to generate wave energy; at the same time, the structure acts as a wave breaker. This technique can be applied to various coastal structures to converge the functions of renewable energy generator and the wave reducing structure. This technique of using piezoelectric sensor is relatively inexpensive that can be used for economic purposes as well. Throughout the study, usability of the existing coastal structure and characteristics of current research trend in the ocean wave energy retrieval of the wave power generators have been analyzed. Hydrographic analysis of this technique has been conducted by hydraulic model experiment using 2D wave flume and confirmed that the wave pressure and voltages maximize when higher wave with longer period of wave induces. Throughout the experiment, correlations of generation volume and wave conditions have been found.

The study of composite materials offers engineers and manufacturers essential insights into understanding failure criteria, initial failure onset, and damage propagation within laminates. This research delves into examining the growth of impact-induced damage and identifying Hertz failure thresholds and maximum force limits across three distinct composite types. Through impact testing, it is observed that the strength of composite materials significantly rises under dynamic loading conditions compared to static loading scenarios, underscoring the material's sensitivity to strain rate.Composite materials play a crucial role in providing effective ballistic protection as part of armor solutions. These materials encounter impact loads of varying energy levels depending on their specific application. Ensuring adequate protection involves a meticulous design and manufacturing process capable of withstanding low-energy impacts, such as those from dropped tools during operational and maintenance tasks, intermediate-energy impacts caused by external materials striking the surface, and high-energy impacts from weapons.Fiber-reinforced composite materials find extensive utilization across aviation, marine, and land platforms, owing to their remarkable specific strength, weight reduction benefits, and manufacturing convenience. These materials hold pivotal roles in the aerospace and defense sectors as well. Polyester resins serve as a cost-effective and user-friendly alternative to epoxy resins in many fiberglass applications. This study focuses on exploring the low-velocity impact behavior of E-Glass composites, which are more economically viable and widely produced compared to armed composites. The research examines three distinct test samples to analyze the impact characteristics of these materials.

This paper presents a comprehensive examination of advanced aerospace structures and materials, focusing on their critical role in modern aerospace engineering applications. The study explores the evolution of structural design principles, material selection strategies, and performance optimization techniques used in high-speed and high-temperature environments. Emphasis is placed on lightweight structural systems, high-strength alloys, composite materials, and emerging smart materials that enhance efficiency, durability, and safety.

The paper further investigates the mechanical behavior of aerospace materials under extreme loading conditions, including thermal stress, fatigue, and aerodynamic forces. Advanced manufacturing techniques, such as additive manufacturing and hybrid material integration, are also discussed as key enablers of next-generation aerospace systems. Additionally, the research highlights the importance of structural reliability, damage tolerance, and sustainability in aerospace design.

By integrating theoretical concepts with practical engineering applications, this work provides a structured framework for understanding the relationship between material innovation and structural performance. The findings contribute to the development of more efficient, resilient, and high-performance aerospace systems, supporting ongoing advancements in both civil and military aviation.

FRP bridge decks are designed to withstand high load levels and a lifetime of several ten years, facing an extremely high number of load cycles. The fatigue life and degradation of the mechanical properties are needed to be essentially considered during the service of the FRP deck. In the present study, a novel electrically conductive coating was developed with a function of strain monitoring for the FRP bridge deck. An epoxy resin was modified with multi-walled nanotube (MWCNT) in order to achieve electrical conductivity. Processing, structure and properties of the MWCNT-epoxy nanocomposite were optimized, and the correlation between the strain level and electrical conductivity of the coating was set up. The conductivity of the coating on the FRP bridge deck is tracked with a simple electrical measurement, and the strain of the FRP bridge deck is obtained through the determined conductivity ~ strain relationship. It is worth noting that the damage modes of the coatings (also the coated FRP surface) can be determined from the conductivity curves. Together with the easy application and data collection, such coating has a high potential for the application in stress/strain and health monitoring.

Single-phase polycrystalline samples of lead titanate with perovskite structure have been synthesized using solid-state reaction technique. The processing parameters have been optimized to obtain phase pure, dense, crack-free, and homogeneous samples. The sintering behavior of PT-powders has been investigated using X-ray diffraction patterns. The X-ray powder diffraction data have been analyzed to confirm the phase formation and phase purity, to obtain unit cell parameters and unit cell volume. The porosity of the samples has been obtained through X-ray density and bulk density. The average particle sizes of the phase pure samples were obtained from the X-ray peak width using Scherrer's formula. The influence of sintering temperature and time on the microstructure of samples has also been studied by carrying out SEM investigations. The notable feature of this microstructure study shows that the samples sintered at 900 ∘ C for 12 hours possess a fairly uniform grain distribution. The electrical behavior (complex impedance Z * , complex permittivity 𝜀 * , etc.) of the samples sintered at 900 ∘ C for 12 hours has been studied by complex impedance spectroscopy. The temperature variation of real permittivity gives evidence of the ferroelectric phase transition as well as of the relaxation behavior.

Il presente trattato intende superare le interpretazioni metafisiche e sociocultali della politica, radicando l'agire umano nella sua natura più profonda: quella di un sistema di particelle cariche regolate dalle leggi della termodinamica e della meccanica quantistica. L'ipotesi centrale è che i conflitti, le alleanze e le ideologie non siano scelte arbitrarie della coscienza, ma configurazioni energetiche necessarie, dettate dall'interazione tra campi elettromagnetici individuali e collettivi.

Adaptive metamaterial skins capable of sensing and responding to environmental disturbances
represent a significant step beyond conventional passive protective materials. This Part-II study
extends the Kagome metaskin architecture with forward sensor scanning, transformer-based distur-
bance prediction, photonic command propagation, and split neuromorphic control loops for defense
and repair. We evaluate three architectures (baseline reactive, dual-SNN, and predictive photonic)
under four representative space hazards: Van Allen radiation, plasma storm turbulence, microme-
teoroid cloud impacts, and gamma burst exposure. Across N = 400 nodes, 500 time steps, and 8
seeds per event, dual-SNN control reduces mean phase-loss from approximately 0.0107 to 0.0045
(about 58.3%), shortens mean recovery time from approximately 277.69 to 190.94 steps (about
31.2%), and lowers mean residual stress from approximately 0.0325 to 0.0251 (about 22.9%) ver-
sus baseline. Predictive photonic pre-arming further improves reductions to approximately 0.0043
(about 60.2% phase-loss reduction), 190.75 steps (about 31.3% recovery-time reduction), and 0.0245
(about 24.5% residual-stress reduction), while preserving disturbance containment under severe
event classes. Seed-level analysis confirms stable ranking across hazards and shows a robust reduc-
tion in stabilization burden. The results support a practical pathway from reactive metamaterial
behavior toward distributed structural intelligence with sensor-informed anticipatory control.

Atomic-level metallurgy integrates nanoscale engineering and AI-driven optimisation to create self-adjusting metallic systems. This foresighting paper explores atomic-scale alloy design, adaptive microstructures, and self-optimising materials. It analyses applications in extreme environments, aerospace, and advanced manufacturing. A research agenda is proposed for advancing atomic-level metallurgy in Africa.

This paper presents a fully coupled Multiphysics finite element modal analysis of a Truncated Magnetoelectric Shell (TMEE) consisting of a Barium Titanate (BaTiO₃) piezoelectric layer and a Cobalt Ferrite (CoFe₂O₄) magnetostrictive layer arranged in a truncated cone (frustum) geometry. Simulations were performed in COMSOL Multiphysics 6.0 using simultaneous Solid Mechanics, Electrostatics, and Magnetic Fields physics interfaces. Four boundary conditions were investigated: Clamped-Clamped (CC), Clamped-Free (CF), Simply Supported-Clamped (SS-C), and Simply Supported-Simply Supported (SS-SS). Up to 8 Eigen frequencies were extracted for each case, and their 3D displacement-magnitude mode shapes were visualised on a revolved geometry. Results reveal an eigen spectrum spanning approximately 310–990 Hz across all four configurations. These findings offer comprehensive design guidance for tuning MEE shell resonance by selecting support conditions.
Keywords: Modal analysis, Barium

Alpha-Fe2O3 nanorods are synthesized through a hydrothermal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods. The device can respond to ethanol vapour in a concentration range from 1 to 1500 parts per million and shows both p-type and n-type responding characteristics during the investigation of the ethanol sensing. The sensor displays a p-type characteristic when the ethanol concentration is low and converted into an n-type characteristic as the concentration exceeds a certain value. Such a phenomenon is attributed to the chemisorbed oxygen, which leads to different modifications of the energy band at the surface, namely, depletion layer or inversion layer.

A structure based on a smart material and a PID control loop is presented in this paper. A glass fiber reinforced plastic material is instrumented with Fiber Bragg Gratings (FBG) and Shape Memory Alloy (SMA) actuators. The smart material and the smart structure are both successfully checked by being subjected to different operational conditions at the laboratory. Very good responses are obtained under both slow and quicker varying conditions.

The paper explores the ability of numerical simulations for Lamb wave propagation in plates exposed to temperature fluctuations. The local interaction simulation approach is used for wave propagation modelling. The newly developed parallel computation technology -offered by modern Graphics Processing Units (GPUs) and Compute Unified Device Architecture (CUDA) used in low-cost graphical cards -is used in these numerical simulations. This allows for very efficient wave propagation simulation for various temperatures. Numerical simulation results can be used more effectively to develop new signal processing techniques to compensate for temperature effects.

This paper focuses on the dynamic tensile response of glass-graphite/epoxy composites illustrating improvement in energy absorption through hybridization. The dynamic response and energy absorption characteristics of pultruded hybrid combinations of glass and graphite fibers in an epoxy matrix subjected to induced transverse tension at high strain-rate in a modified Split Hopkinson Pressure Bar (SHPB) apparatus, are presented. Transverse tensile strength was determined by diametral compression of disc samples (Brazilian indirect tensile test method). Diametral crack initiation and strain to failure were monitored with a Shimadzu HPV-2 high-speed video camera at a recording speed of 500,000 fps and Digital Image Correlation (DIC). Adequate measures were taken to ensure that initiation of specimen failure occurred at the exact center of the disc specimen, and propagated through the diameter along the compressive loading axis, for the induced transverse tension tests to be valid. A stu...

Poly(urea-formaldehyde) (PUF) microcapsules that enclose dicyclopentadiene (DCPD) were successfully prepared by in situ polymerization. The effect of diverse process parameters and concentrations of ingredients on the product yield and quality was investigated. After optimizing the procedure high yields of microcapsules were obtained (up to 89%) which appeared in the form of a free-flowing white powder. The morphology of the microcapsules was observed by digital microscopy, optical microscopy (OM), and field emission gun scanning electron microscopy (FESEM). FTIR and 1 H-NMR were employed to analyze the chemical structure and content of the core material. The thermal properties were characterized utilizing DSC and TGA. The microcapsules could be incorporated into another polymeric host material. In the event the host material cracks due to excessive stress or strong impact, the microcapsules would rupture to release the DCPD, which could polymerize to repair the crack, thus autonomously heal the material. To enhance the properties of the microcapsule shell, the urea was partially replaced with up to 5% melamine. Different microscopic techniques, FTIR spectroscopy and DSC were employed to examine the capsule shell, whereas the core content was confirmed by 1 H-NMR. Capsules in the range of 50-300 µm were then embedded in a light curable dental composite matrix consisting of bisphenol-Aglycidyl dimethacrylate (Bis-GMA) and triethylene-glycol dimethacrylate (TEGDMA). Two different amounts (3 wt% and 6 wt%) of microcapsules were embedded into the dental host material and their performances were evaluated through mechanical tests. OM examination of the light-cured specimens showed a random distribution of the microspheres throughout the host material, whereas FESEM

In many investigations, large number of process, or design parameters that are initially thought to affect the outcomes or outputs may not really have statistical significant influence on them. Screening experiments are used to identify the key parameters (factors) that significantly affect these outcomes. In this investigation, Plackett-Burman screening design was used to identify the factors that influence the surface properties of titanium alloy (Ti-6Al-4V) during electro-discharge machining (EDM) with Cu-TaC electrodes. These properties are the surface roughness and the surface micro-hardness. The experimental design has seven factors where each factor is set at two different levels. These factors include the TaC composition in the electrode and its compacting pressure. Others are urea concentration in the dielectric fluid, machining peak current, pulse duration, duty factor and the gap voltage. An 8-trial runs was used in conducting the investigation. The analysis of variance w...

Different industrial mixing methods and some of their combinations ((1) ultrasound; (2) mechanical stirring; (3) by roller machine; (4) by gears machine; and (5) ultrasound radiation + high stirring) were investigated for incorporating multi-walled carbon nanotubes (MWCNT) into a resin based on an aeronautical epoxy precursor cured with diaminodiphenylsulfone (DDS). The effect of different parameters, ultrasound intensity, number of cycles, type of blade, and gear speed on the nanofiller dispersion were analyzed. The inclusion of the nanofiller in the resin causes a drastic increase in the viscosity, preventing the homogenization of the resin and a drastic increase in temperature in the zones closest to the ultrasound probe. To face these challenges, the application of high-speed agitation simultaneously with the application of ultrasonic radiation was applied. This allowed, on the one hand, a homogeneous dispersion, and on the other hand, an improvement of the dissipation of heat g...

This paper demonstrates a case study of a combined application of smart materials in a thermal energy harvester with vibrating action. The conceptual design of the harvester is based on a Shape Memory Alloy wire attached to the free end of a piezoelectric flexible cantilever beam intended for generation of electrical energy utilizing a constant heat source. A mathematical model containing three differential equations describing the dynamics of the mechanical, electrical and thermal subsystems is developed. The Shape Memory Alloy hysteretic behaviour is considered in the mathematical model. An essential observation is the system oscillates at two frequencies lower one of which depends on the temperature time constant and the higher one is determined by the natural frequency of the mechanical subsystem. The comparison of the numerical solutions and the experimentally obtained graphs of the harvester output characteristics shows a good degree of coincidence.

Last few decades have seen emergence of newer dental materials with enhanced biological properties. Search for an ideal restorative material leads to the discovery of entirely newer generation of materials called the "smart materials". These materials are said to be smart as they can be altered by different types of stimulus such as temperature, moisture, ph, stress, electric and magnetic field, etc. These materials have the inherent quality to sense any change in the environment and react according to such changes. Thus, they are called "responsive materials". Usage of these smart materials has revolutionised dentistry. There are various smart materials available such as smart composites, compomers, smart ceramics, smart impression materials, etc.

The use of shunt of piezoelectric transducers to damp mechanical vibrations is an interesting approach thanks to its low cost and the light weight of the actuators used. Among the different ways to build the shunt impedance, the use of negative capacitances is very attractive because it allows for high damping performances with low power required by the control system. Negative capacitances do not exist in the actual world but they can be designed and built using circuits based on operational amplifiers. The use of shunt circuits based on a negative capacitance coupled to a resistance allows to have a broadband control. This paper explains how to increase the bandwidth of the controller by adding to such a shunt circuit an inductance. The dynamics of the controlled system is solved analytically and the reason why the introduction of the inductance is able to give the mentioned improvement is made clear also using numerical simulations. Furthermore, this improvement also allows to increase the attenuation performance. The conditions necessary to assure the stability of the electro-mechanical system are found and explained.

The Poisson’s ratio, a property which quantifies the changes in thickness when a material is stretched and compressed, can be determined as the negative of the transverse strain over the applied strain. In the scientific literature, there are various ways how strain may be defined and the actual definition used could result in a different Poisson’s ratio being computed. This paper will look in more detail at this by comparing the more commonly used forms of strain and the Poisson’s ratio that is computable from them. More specifically, an attempt is made to assess through examples on the usefulness of the various formulations to properly describe what can actually be observed, thus providing a clearer picture of which form of Poisson’s ratio should be used in analytical modelling.

This study considers a 3D basic unit-cell proposed for auxetic and non-auxetic foams namely the elongated hexagonal dodecahedron deforming through changes in angle between its ligaments (idealised hinging model). This structure was studied in detail for the potential of exhibiting negative Poisson's ratio and/or negative compressibility by means of a method based on standard force-field molecular modelling technique, termed as Empirical Modelling Using Dummy Atoms (EMUDA). The mechanical properties obtained from this method were then compared to a previously published analytical model of this structure [Grima J N, Caruana-Gauci R, Attard D, and Gatt R 2012, Proc. Roy. Soc. A 468 3121], and found to be in good agreement with each other. The results showed that this system can exhibit zero Poisson's ratios in one of its planes and positive or negative Poisson's ratios in other planes, depending on the geometry of the model. It was also shown that under certain conditions, negative linear and/or area compressibility was also exhibited.

Chiral systems are a class of structures, which may exhibit the anomalous property of a negative Poisson's ratio. Proposed by Wojciechowski and implemented later by Lakes, these structures have aroused interest due to their remarkable mechanical properties and numerous potential applications. In view of this, this paper investigates the on‐axis mechanical properties of the general forms of the flexing anti‐tetrachiral system through analytical and finite element models. The results suggest that these are highly dependent on the geometry (the ratio of ligament lengths, thicknesses, and radius of nodes) and material properties of the constituent materials. We also show that the rigidity of an anti‐tetrachiral system can be changed without altering the Poisson's ratio.The anti‐tetrachiral system, with the unit cell shown in red.

Typically, an active structural health monitoring system (SHM) consists of an integrated network of actuator/sensor piezoceramic elements that inject and receive ultrasound pulses into the host structure collecting information about structural health. Although numerical simulation has been used extensively in understanding and aiding in the design of such systems, analytical models are still the primary vehicle for understanding actuation and sensing mechanisms. Being based on simplified assumptions it suffers from certain limitations with respect to its extension to SHM systems. The main assumption of equivalent loading is neglecting the mechanical coupling by replacing the piezoceramic with equivalent load(s). The present work addresses two of the limitations of this assumption, namely the effect of the thickness of the piezoceramic element on the equivalent load in dynamic setting at high frequency. This study is done via a novel formulation based on earlier work considering Lamb...

This study presents a simulation-driven investigation into the optimization of a lithium niobate (LiNbO 3)-based pyroelectric sensor for pulsed laser detection. Using COMSOL Multiphysics 6.0, a transient multiphysics model was developed to analyze the sensor's thermal and electrical responses under a 1 s laser energy flux of 500 W m-2. The effects of geometrical parameters, including crystal thickness and disk radius, as well as the external load resistance, were systematically evaluated. A timedependent energy input profile was implemented as a step-function laser pulse, and its impact on voltage, current, power, and temperature profiles was examined in detail. The study revealed that increasing the disk radius from 1 mm to 5 mm enhanced the charge-generating area and improved output performance, albeit at the cost of slower thermal decay. Similarly, increasing the crystal thickness from 0.01 mm to 0.04 mm significantly improved voltage sensitivity, reaching up to 2.0 μV K-1 , while also minimizing temperature gradients across the crystal. Electrical response analysis showed that higher load resistances increased output voltage and reduced current, with peak power output (12.18 fW) observed at 500 MΩ, indicating optimal impedance matching. The thermal behavior was largely unaffected by electrical loading, confirming that it is primarily governed by the material's physical properties and the applied laser energy. Additionally, the comparison of thermal and electrical time constants illustrated how sensor performance can shift from thermally to electrically limited, depending on design parameters. The study provides detailed insights into the sensor's operational dynamics and establishes an optimized design space. A configuration of 5 mm radius, 0.04 mm thickness, and 500 MΩ load resistance offers a promising balance of signal amplitude, sensitivity, and temporal stability. These findings offer valuable guidance for the design and future experimental realization of high-performance pyroelectric sensors.

Origami has several attractive attributes including deployability and portability which have been extensively adapted in designs of robotic devices. Drawing inspiration from foldable origami structures, this paper presents an engineering design process for fast making deployable modules of soft continuum arms. The process is illustrated with an example which adapts a modified accordion fold pattern to a lightweight deployable module. Kinematic models of the four-sided Accordion fold pattern is explored in terms of mechanism theory. Taking account of both the kinematic model and the materials selection, a 2D flat sheet model of the four-sided Accordion fold pattern is obtained for 3D printing. Following the design process, the deployable module is then fabricated by laminating 3D printed origami skeleton and flexible thermoplastic polyurethane (TPU) coated fabric. Preliminary tests of the prototype shown that the folding motion are enabled mainly by the flexible fabric between the gaps of thick panels of the origami skeleton and matches the kinematic analysis. The proposed approach has advantages of quick scaling dimensions, cost effective and fast fabricating thus allowing adaptive design according to specific demands of various tasks.

The CBCM is a thermal activated composite material. The thermal activation is made thanks to carbon yarns which are connected to a power supply. If the anisotropy of the structure is well organized, the desired deformation is reached when the temperature within the composite is rising. To obtain a morphing composite structure, a CBCM part can be locally incorporated in a classical composite structure. The first part of this work consists in presenting the experimental results for two examples of composite beams. The second part is about the FEM model (Abaqus software) and the different problems of non linearity which have to be taken into account.

For shape morphing application, thermal activation coupling to a bimetallic strip effect can be a substitute for classical actuators, piezoelectrical or shape memory alloys. The controlled behaviour of composite material (CBCM) is a thermaly activated composite material. The thermal activation is made thanks to carbon yarns which are connected to a power supply. If the anisotropy of the structure is well organized, the desired deformation is reached when the temperature within the composite is rising. To obtain a CBCM morphing composite structure, it is necessary to design a specific structure. The aim of this work is to show that it is possible to adapt the CBCM principle in order to transform any kind of classical composite structure to an active structure. The first part of this work consists in presenting the experimental results for two examples of composite beams. The second part is about the active structure FEM modeling and the development of adapted tools for this particula...