Search Results (161)

Let $K\subset {\mathbb{R}}^n$ be a bounded convex body. We prove a lattice-averaging formula that gives upper bounds for the number of unit balls required to cover K. If the Voronoi cell P of a lattice is contained in the Euclidean unit ball, then some translate and rotation of the lattice produces a covering whose size is at most a linear combination of the intrinsic volumes of K; the coefficients are determined by the intrinsic volumes of P. The proof averages the number of Voronoi cells meeting K over one fundamental cell and over $SO\left(n\right)$. For the regular hexagonal lattice in ${\mathbb{R}}^2$, the formula reproduces the classical planar Blaschke bound. For the cubic lattice, it gives a closed-form estimate in every dimension $n\ge 2$. In ${\mathbb{R}}^3$, explicit computations for the cubic, face-centered cubic, and body-centered cubic Voronoi cells show that the body-centered cubic lattice has the smallest coefficientwise bound among these three lattices. In ${\mathbb{R}}^4$, the intrinsic volumes of the $A_4^{\ast }$ permutohedron are computed from its graphical-zonotope representation, leading to a sharper bound than for the cubic lattice. Full article

The transition from internal combustion engine vehicles to battery electric vehicles has changed the acoustic design problem in automotive engineering. The absence of combustion-related masking increases the perceptibility of tonal and narrowband sources, including gear whine, electric motor orders, inverter-related components, tire cavity resonances, auxiliary system noise, and lightweight-panel radiation. At the same time, mass-based acoustic treatments conflict with electric vehicle lightweighting, range, cost, and sustainability targets. Vibroacoustic metamaterials offer an alternative route by manipulating elastic and acoustic wave propagation through architected geometries, local resonances, periodicity, membranes, lattice architectures, and adaptive or topological wave-control mechanisms. This review examines vibroacoustic metamaterials for low-frequency electric vehicle noise, vibration, and harshness (EV NVH) from an engineering perspective. It covers mechanisms, EV-specific NVH problems, component applications, materials, manufacturing, modeling, validation, AI-assisted design, sustainability, and technology readiness. Particular emphasis is placed on order-targeted, path-oriented, manufacturable, and experimentally validated solutions for electric-drive (e-drive) housings, wheel arches, battery enclosures, body panels, covers, and auxiliary systems. The review concludes that vibroacoustic metamaterials are most promising when integrated into conventional NVH workflows through order analysis, transfer path ranking, robust resonator tuning, durability validation, and multi-objective design optimization. Full article

The oxygen evolution reaction (OER) is a key kinetic bottleneck in water electrolysis because it involves multistep proton-coupled electron transfer, the evolution of oxygen-containing intermediates and O–O bond formation. MXenes, as two-dimensional transition-metal carbides, nitrides and carbonitrides, possess high electrical conductivity, hydrophilic surfaces, tunable surface terminations and adjustable layered structures, making them promising platforms for OER catalyst design. However, their limited intrinsic active sites, sheet restacking and oxidative instability under anodic conditions restrict their direct application. This review firstly discusses the fundamental OER pathways based on the adsorbate evolution mechanism (AEM), lattice oxygen mechanism (LOM) and oxide path mechanism (OPM), providing a mechanistic basis for understanding intermediate adsorption, oxygen activation and working-state evolution. Then, a system framework from low-dimensional and micro-level control to high-dimensional and macro-level integration is constructed. The framework covers four levels: atom and local structure, interface, morphology and composite electrode. Drawing on specific examples, this review analyzes the characteristics and mechanisms of modification strategies from four different perspectives, starting with the basic principles of modification. These strategies include micro-scale, low-dimensional approaches such as “Vacancy and other atomic-Level Regulation”, macro-scale, high-dimensional methods like “Composite Engineering”, as well as intermediate approaches involving “Interface engineering” and “morphology engineering”. Special emphasis is placed on distinguishing between beneficial surface reconstruction of catalytically active hydroxyl oxide species and destructive oxidation. Finally, the review identified the unresolved key challenges, including the fuzziness of active sites, the diversity of initial material states and the lack of stability under industrial conditions, and looked forward to the future direction of reasonable design, operational characterization and device-level evaluation. Through this cross-scale analysis, this review aims to clarify the relationship between structure–activity–stability, and provide practical guidance for designing efficient, durable and experimentally verifiable MXene-based OER electrodes. Full article

Al-doped zinc oxide (AZO) thin films were deposited by RF magnetron sputtering using a simple doping approach: aluminum tape was placed directly on the ZnO target. The work focused on understanding how Al incorporation, annealing temperature, and annealing atmosphere affect the structural and electrical behavior of the films, particularly their baseline resistance for gas sensing applications. EDX measurements confirmed that increasing the Al-covered area on the target progressively increased the Al concentration in the deposited layers. XRD analysis showed that higher Al contents and stronger thermal treatments reduced crystallinity and promoted the formation of smaller crystallites. The electrical response changed markedly with both Al incorporation and thermal treatment. Pure ZnO films initially exhibited very high resistance, while annealing reduced it by several orders of magnitude. Further increasing the Al concentration improved conductivity due to the donor effect of Al in the ZnO lattice. Overall, the results show that RF sputtering and post-treatment strategies can provide broad control over the electrical resistance of ZnO-based thin films. This tunability makes AZO coatings attractive for adapting chemoresistive gas sensors to different sensing environments and operating regimes, and deposition and thermal treatment parameters determine the resistance range. Full article

Architected cellular materials are increasingly proposed for electric-vehicle (EV) battery systems as lightweight solutions that can combine crashworthiness, intrusion mitigation and, in some cases, thermal functionality. However, the literature remains fragmented across heterogeneous architectures, metrics and test conditions, which often prevents design-oriented comparison and limits transferability to pack-level implementation. This review consolidates the state of the art on cellular structures for EV battery applications, covering foams, honeycombs, lattice/TPMS architectures and auxetic or bio-inspired concepts. A unified, design-oriented comparative framework is introduced to discuss mechanical performance (e.g., specific energy absorption, peak crushing force, deformation control), thermal considerations and manufacturing–scalability constraints under an EV battery-pack perspective. By explicitly linking cellular architecture selection to pack safety and integration requirements, including limited crush space, joining interfaces, enclosure stiffness and emerging “pack-as-a-structure” concepts, this work translates dispersed results into actionable engineering insights. Finally, decision-oriented guidelines and a selection flowchart are proposed to support early-stage architecture choice and highlight the most critical research gaps, particularly in multiphysics validation, standardized benchmarking and production-ready integration. Full article

Linearly homomorphic signatures (LHSs) are widely used in scenarios such as network coding and the Internet of Things, but their security faces the serious threat of key leakage. To address this issue, this paper introduces a forward secure mechanism into LHSs, aiming to construct a linearly homomorphic signature (LHS) scheme that can resist the risk of key leakage. By combining the binary tree minimal cover set mechanism with lattice-based extension algorithms, we construct an LHS scheme that supports time-period key updates. We prove its forward secure unforgeability under the standard model (SM) by reducing it to the Short Integer Solution (SIS) problem. To the best of our knowledge, this scheme is the first provably secure lattice-based forward secure linearly homomorphic signature (FSLHS) scheme in the SM, filling a theoretical gap in existing research. Furthermore, we apply this scheme to a smart grid data acquisition system and verify its practicality through concrete performance analysis. Full article

A numerical design study is carried out to support the setup of a wind tunnel experiment for the flap cover seal, which will serve as a benchmarking reference database for Fluid–Structure Interaction (FSI) in aeronautics. To this end, 3-D scale-resolving unsteady Large Eddy Simulation (LES) with the Lattice Boltzmann Method (LBM) is carried out using the simulation software ProLB. A new aerodynamic layout for the chosen F15LS (Large-Scale) high-lift wing model is established to fit the high-lift wing in the DLR-AWB tunnel. The design process involves variations in the leading-edge nose contour’s streamwise length and camber lines (inducing a negative S-shape) to reduce the leading-edge suction peak, thereby lowering the absolute lift while preserving the flap operating conditions. Initial simulations utilize a simplified periodic LES slice and a theory of the method of images to model wind tunnel jet flow deflection, culminating in a full-span 3-D WM-LES-LBM simulation of the entire wind tunnel installation, including free shear layers, to confirm the designed performance of the modified F15LS. This simulation serves to make informed decisions on model settings such as the boundary layer fence and model-nozzle distance. The successful experimental validation of critical performance characteristics, including angle-of-attack requirements and flow deflection, confirms the fidelity of the pre-test WM-LES-LBM evaluation. Full article

We review the structure of pseudoscalar mesons within an algebraic model formulated in the light-front framework. The approach provides a unified description of leading-twist parton distribution amplitudes, light-front wave functions, generalized parton distributions, parton distribution functions, elastic electromagnetic form factors, charge radii, and impact-parameter space distributions, all obtained from the same underlying Bethe–Salpeter wave-function representation. The analysis covers light mesons $(\pi ,K)$, the mixed $\eta$–${\eta }^{\prime }$ system, heavy–light states $(D,D_s,B,B_s,B_c)$, and heavy quarkonia $({\eta }_c,{\eta }_b)$, thereby enabling a systematic study of quark-mass effects, flavor-symmetry breaking, and the transition from emergent hadronic mass to heavy-quark dynamics. Where available, results are compared with experimental measurements, functional methods such as lattice-QCD calculations and Dyson–Schwinger Equation formalism, and other phenomenological approaches. The algebraic model thus offers a transparent, symmetry-preserving, and analytically tractable framework for connecting the longitudinal, transverse-momentum, and spatial structure of pseudoscalar mesons across all quark-mass regimes. Full article

Functionally graded materials (FGMs) effectively alleviate residual stress induced by physical property mismatch at dissimilar material interfaces through a graded transition in composition or structure. Among these, the matching of the coefficient of thermal expansion (CTE) is a core indicator for ensuring the service reliability of the joint. Traditional composition design relies on empirical trial-and-error, which makes it difficult to efficiently identify the optimal path in a high-dimensional composition space. This study proposes a data-driven, machine learning-assisted composition design method. Based on a high-precision dataset covering 15 elements and 747 CTE data points, six typical regression models were systematically evaluated. The results show that the random forest (RF) model achieves the best performance, with a coefficient of determination (R²) of 0.929 and a root mean square error (RMSE) of 0.658 on the test set. Using the SHapley Additive exPlanations (SHAP) method, the lattice constant (c), Young’s modulus (YM), and temperature (T) were identified as the key physical descriptors governing the thermal expansion behavior. Experimental validation shows that the CTE prediction deviation of the model for the high-performance Fe-based alloy Norem02 in the range of 20–300 °C is only 0.89%. Based on this framework, the composition of the 316L/Norem02 transition layer was successfully designed in this study. This effectively reduced the interfacial thermal expansion mismatch. Consequently, it provides a reliable theoretical basis for the rational design of dissimilar material interfaces under extreme service conditions. Full article

We develop Cs_xFA_1−xPbI₃ perovskite photodetectors with varying Cs content in the x = 0.05–0.25 range to identify the most stable cubic-lattice perovskite composition for visible-light photodetection. The perovskite layers were deposited by the spin-coating technique on a nickel oxide p-type contact and then were covered with C₆₀/Ag electron contact to obtain a vertical pin diode structure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements show that x = 0.1–0.2 provides the most stable lattice and pinhole-free perovskite layers. The photocurrents are linear in an extremely wide 1 nW–10 mW excitation power range, providing photoresponsivity of 0.28 A/W at 532 nm (green light), similar to that of Si photodiodes. The testing of the photodetectors using picosecond pulses provided their rise times and fall times. The x = 0.2 composition provided the shortest rise time values of 27.5 ns, leading to a detector modulation bandwidth of 12.7 MHz. This indicates that this perovskite composition is suitable for replacing silicon photodetectors in cost-efficient light detection systems for imaging and light communication applications such as Li-Fi. Full article

The rapid advancement of quantum computing poses a severe threat to traditional public key cryptosystems. Lattice-based cryptography has emerged as a core candidate for post-quantum cryptography due to its presumed quantum resistance, robust security foundations, and functional versatility, with its concrete security relying on the computational hardness of lattice problems. Existing lattice-based cryptography surveys mainly focus on cryptosystem design, scheme comparisons, and post-quantum cryptography standardization progress, with only cursory coverage of classical lattice algorithms that underpin the concrete security of lattice-based cryptography. We present the first systematic survey of classical lattice algorithms, focusing on two core categories of algorithms for solving lattice problems: approximate algorithms and exact algorithms. The approximate algorithms cover mainstream lattice basis reduction methods such as Lenstra–Lenstra–Lovász (LLL), Block Korkine–Zolotarev (BKZ), and General Sieve Kernel (G6K) algorithms, as well as alternative frameworks. The exact algorithms encompass dominant techniques like enumeration and sieving algorithms, along with alternative strategies. We systematically trace the evolutionary trajectory and inherent logical connections of various algorithms, clarify their core mechanisms, and identify promising future research directions. This survey not only serves as an introductory guide for beginners but also provides a valuable reference for seasoned researchers, facilitating the concrete security evaluation of lattice-based cryptosystems and the design of novel lattice algorithms. Full article

The significant disparity between the size and electronegativity of N and group-V (P, As, Sb) atoms in dilute III–V-Ns remains a cornerstone for developing the next-generation electronics. Variations in the structural, optical, and phonon properties of the quaternary GaAs_1−x−ySb_yN_x alloys are being used for improving the high-performance photovoltaic energy and optoelectronic technologies. Bandgap ${\mathrm{E}}_{\mathrm{g}}$ tunability has assisted efficient light emission/detection to cover the crucial optical fiber wavelengths for the low-cost integrated chips in data communications and sensing devices. The lattice dynamical properties of these materials are critical for assessing the reliability to evaluate the performance of long-wavelength lasers, photodetectors, and multi-junction solar cells. Our systematic Raman measurements on high-quality MBE grown $\mathrm{G}\mathrm{a}{\mathrm{A}\mathrm{s}}_{0.946}{\mathrm{S}\mathrm{b}}_{0.032}{\mathrm{N}}_{0.022}$/GaAs samples have detected ${\mathsf{\omega }}_{\mathrm{T}\mathrm{O}\left(\mathsf{\Gamma }\right)}^{\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}}$ and ${\mathsf{\omega }}_{\mathrm{T}\mathrm{O}\left(\mathsf{\Gamma }\right)}^{\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}}$ phonons along with a high frequency N_As local mode near ~476 cm⁻¹. Weak phonon structures on both sides of the broad 476 cm⁻¹ band are interpreted forming a complex N_As–Ga–Sb_As defect center. Using a realistic rigid-ion model in the Green’s function framework, the simulations of impurity modes for isolated and complex defects have provided corroboration to the experimental data. Full article

Physical-layer security (PLS) provides an information-theoretic framework for securing wireless communications by exploiting channel and signal-structure asymmetries, thereby avoiding reliance on computational hardness assumptions. Within this setting, lattice codes and their algebraic constructions play a central role in achieving secrecy over Gaussian and fading wiretap channels. This article offers a comprehensive survey of lattice-based wiretap coding, covering foundational concepts in algebraic number theory, Construction A over number fields, and the structure of modular and unimodular lattice families. We review key secrecy metrics, including secrecy gain, flatness factor, and equivocation, and consolidate classical and recent results to provide a unified perspective that links wireless-channel models with their underlying algebraic lattice structures. In addition, we review a newly proposed family of p-modular lattices in Khodaiemehr, H., 2018 constructed from cyclotomic fields $\mathbb{Q}\left({\zeta }_p\right)$ for primes $p\equiv 1\left(\mathrm{mod}4\right)$ via a generalized Construction A framework. We characterize their algebraic and geometric properties and establish a non-existence theorem showing that such constructions cannot be extended to prime-power cyclotomic fields $\mathbb{Q}\left({\zeta }_{p^n}\right)$ with $n>1$. Finally, motivated by the fact that these p-modular lattices naturally yield mixed-signature structures for which classical theta series diverge, we integrate recent advances on indefinite theta series and modular completions. Drawing on Vignéras’ differential framework and generalized error functions, we outline how modularly completed indefinite theta series provide a principled analytic foundation for defining secrecy-relevant quantities in the indefinite setting. Overall, this work serves both as a survey of algebraic lattice techniques for PLS and as a source of new design insights for secure wireless communication systems. Full article

In 1994, P. Shor discovered quantum algorithms that can break both the RSA cryptosystem and the ElGamal cryptosystem. In 2007, D-Wave demonstrated the first quantum computer. These events and further developments have brought a crisis to secret communication. In 2016, the National Institute of Standards and Technology (NIST) launched a global project to solicit and select a handful of encryption algorithms with the ability to resist quantum computer attacks. In 2022, it announced four candidates, CRYSTALS-Kyber, CRYSTALS-Dilithium, Falcon, and Sphincs+, for post-quantum cryptography standards. The first three are based on lattice theory and the last on a hash function. The security of lattice-based cryptosystems relies on the computational complexity of the shortest vector problem (SVP), the closest vector problem (CVP), and their generalizations. As we will explain, the SVP is a ball-packing problem, and the CVP is a ball-covering problem. Furthermore, both the SVP and CVP are equivalent to arithmetic problems for positive definite quadratic forms. This paper will briefly describe the mathematical problems on which lattice-based cryptography is built so that cryptographers can extend their views and learn something useful. Full article

Quantum computing threatens widely deployed public-key cryptosystems, accelerating the adoption of Post-Quantum Cryptography (PQC) in practical systems. Beyond asymptotic security, the feasibility of PQC deployments depends on measured performance on real hardware and on implementation-level overheads. This paper presents an experimental evaluation of five post-quantum digital signature schemes (CRYSTALS-Dilithium, HAWK, SQISign, SNOVA, and SPHINCS+) and three key encapsulation mechanisms (Kyber, HQC, and BIKE) selected to cover multiple PQC design families and parameterizations used in practice. We implement a TCP client–server testbed in Python that invokes C implementations for each primitive—via standalone executables and, where provided, in-process dynamic libraries—and benchmarks key generation, encapsulation/decapsulation, and signature generation/verification on two Windows 11 commodity processors: an AMD Ryzen 7 4000 (8 cores, 16 threads, 1.8 GHz) and an Intel Core i5-1035G1 (4 cores, 8 threads, 1.0 GHz). Each operation is repeated ten times under a low-interference setup, and results are aggregated as mean (with 95% confidence intervals) timings over repeated runs. Across the evaluated configurations, lattice-based schemes (Kyber, Dilithium, HAWK) show the lowest computational cost, while code-based KEMs (HQC, BIKE), isogeny-based (SQISign), and multivariate (SNOVA) signatures incur higher overhead. Hash-based SPHINCS+ exhibits larger artifacts and higher signing latency depending on the parameterization. The AMD platform consistently outperforms the Intel platform, illustrating the impact of CPU characteristics on observed PQC overheads. These results provide comparative evidence to support primitive selection and capacity planning for quantum-resistant deployments, while motivating future end-to-end validation in protocol and web service settings. Full article