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In order to prevent the reconnaissance of synthetic aperture radar-ground moving target indication (SAR-GMTI) to moving targets on the ground, a smart jamming method of intermittent sampling based on noise multiplication modulation is proposed. Combining the intermittent sampling jamming with noise multiplication modulation, the jamming method can not only guarantee transceiver isolation, but also efficiently produce different effects of multiple target deception and dense target cover by the offline template design. The process performs intermittent sampling firstly, and then multiply product modulation with the designed template. The jamming signal model is established and the interference effect on SAR and SAR-GMTI is analyzed, the influence of reconnaissance error on performance is explained. The results show that the proposed method can make up for the defect of intermittent sampling effectively, whose distribution of false target is regular and distinguishable. The jamming scope is expanded and the jamming result is flexible. [ABSTRACT FROM AUTHOR]

In this paper, we introduce ∗-almost independent rings of Krull type (∗-almost IRKTs) and ∗-almost generalized Krull domains (∗-almost GKDs) in the general theory of almost factoriality, neither of which need be integrally closed. This fills a gap left in [D. D. Anderson and M. Zafrullah, On∗-Semi-Homogeneous Integral Domains, Advances in Commutative Algebra (Springer, Singapore, 2019)]. We characterize them by ∗-almost super-SH domains, where a domain D is called a ∗-almost super-SH domain if every nonzero proper principal ideal of D is a ∗-product of ∗-almost super-homogeneous ideals. We prove that (1) a domain D is a ∗-almost IRKT if and only if D is a ∗-almost super-SH domain, (2) a domain is a ∗-almost GKD if and only if D is a type 1 ∗-almost super-SH domain and (3) a domain D is a ∗-almost IRKT and an AGCD-domain if and only if D is a ∗-afg-SH domain. Further, we characterize them by their integral closures. For example, we prove that a domain D is an almost IRKT if and only if D ⊆ D ¯ is a root extension with D t -linked under D ¯ and D ¯ is an IRKT. Examples are given to illustrate the new concepts. [ABSTRACT FROM AUTHOR]

The traditional synthetic aperture radar ground moving target indication (SAR-GMTI) deceptive jamming method based on dual synthetic jammers can generate very similar false moving targets. However, when the method is used to create a large number of false moving targets, the computational burden is very high, which does not meet the need for real-time jamming in electronic warfare. Therefore, we propose an algorithm for fast generation of dense false moving targets. This proposed method is based on the theory of dual jammers generating false stationary targets against dual-channel SAR-GMTI. By adding complex coefficient modulation to each jammer, the false targets can be detected as moving ones. In addition, by using an algorithm of SAR large scenes deception jamming, the computational burden is reduced when the jammer creates dense false moving targets which makes the proposed method applicable to engineering. Simulation experiments verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Let D be an integral domain. Then D is an almost valuation (AV)-domain if for a , b ∈ D ∖ { 0 } there exists a natural number n with a n | b n or b n | a n. AV-domains are closely related to valuation domains, for example, D is an AV-domain if and only if the integral closure D ¯ is a valuation domain and D ⊆ D ¯ is a root extension. In this note, we explore various generalizations of DVRs (which we might call almost DVRs) such as Noetherian AV-domains, AV-domains with D ¯ a DVR, and quasilocal and local API-domains (i.e., for { a α } α ∈ Λ ⊆ D , there exists an n with ( { a α n } α ∈ Λ) principal). The structure of complete local AV-domains and API-domains is determined. [ABSTRACT FROM AUTHOR]

Considering the problem that the imaging position of synthetic aperture radar ground moving target indication (SAR-GMTI) of the traditional scattering-wave jamming is fixed, which makes the moving targets at specific position exposed, a compound scattering-wave jamming method based on two dimensional single tune modulation is proposed. According to the time-frequency coupling characteristics of linear frequency modulation signal, this method implements the frequency modulation of intercepted SAR signal in both range and azimuth profiles to control the jamming area, and the modulated jamming is amplified and projected to the metal scatterers. The analytical expression of the jamming imaging result against SAR-GMTI is deduced theoretically and the jamming performance is also analyzed in detail. The theoretical analysis and simulation results demonstrate that the proposed method can tackle the problem that the traditional scattering-wave jamming cannot cover the moving target at any position, and realize the flexible control of jamming imaging area by a fixed jammer and the jamming density by deployment of scatters. The SAR-GMTI can still be jammed even under large scouting error, which will provide some reference value for engineering application. [ABSTRACT FROM AUTHOR]

As an emerging imaging mechanism of synthetic aperture radar (SAR), the recently proposed multiple input multiple output SAR (MIMO-SAR) could obtain much more freedoms than the number of the physical antenna elements by utilizing waveform diversity and space diversity. As a result, it could overcome the limitation of the conventional SAR, and provide effective techniques for applications such as high resolution wide swath (HRWS) imaging, slow moving target detection, mean-time multi-mode operation and so on. This paper summarizes the research status of MIMO-SAR from domestic and abroad, analyzes its concept connotation, technical features and key technologies, and probes into its waveform designing techniques. Finally, combined with system development and practical applications, the developing trend of the MIMO-SAR imaging technique is discussed. [ABSTRACT FROM AUTHOR]

As a kind of novel multi-functional nanocomposite, a ternary hybrid of monodisperse Ni3S4 nanorods/graphitic C3N4 nanosheets/nitrogen-doped graphene with heterostructured architecture is controllably constructed for the first time, illustrating great potential for overall water splitting and the fabrication of sodium-ion batteries. Intensive investigations revealed that the ternary hybrid with robust and intertwined nanostructures possesses shorter diffusion pathways, smaller diffusion resistance and faster transfer speeds of electrons and ions, which could expedite the transport of electrolyte to flood and interact with reaction sites, dynamically and thermodynamically. Notably, the active Ni3S4 nanorods within the unique integrated ternary hybrid embedded in graphitic C3N4 nanosheets over a conducting substrate of nitrogen-doped graphene could strongly avoid agglomeration, abscission, anisotropic volume expansion and irreversible mechanical failure, even during extreme electrochemical reactions. Owing to the integrated effect, the ternary hybrid delivers excellent electrochemical performance with long-term stability during water splitting and cycling durability when used in sodium-ion batteries. In particular, a low onset potential of 40 mV (vs. RHE, J = −1.5 mA cm−2) is observed in the HER process, and the applied potentials are also as small as 1.47 V (vs. RHE) and 1.51 V for the OER and overall water splitting, respectively, at 10 mA cm−2 under the same alkaline conditions. As for sodium-ion batteries, the ternary hybrid possesses an advanced specific capacity of ∼670 mA h g−1 at 100 mA g−1 with particularly excellent rate capabilities and it could even work at a high current density. [ABSTRACT FROM AUTHOR]

It is well known that a domain is a Prüfer domain if and only if for -modules, relative divisibility implies purity. In this paper, we extend this result to Prüfer -multiplication domains (PMDs). To do this, we introduce the concept of -pure exact sequences over commutative rings with zero divisors, and we prove that a domain is a PMD if and only if for -modules, relative divisibility implies -purity. Also, we compare -purity with purity and relative divisibility by giving examples. [ABSTRACT FROM AUTHOR]

MoSe2 as a typical transition metal dichalcogenide holds great potential for energy storage and catalysis but its performance is largely limited by its poor conductivity. Bi2Se3 nanosheets, a kind of topological insulators, possess gapless edges on boundary and show metallic character on surface. According to the principle of complementary, a novel integrated quasiplane structure of MoSe2/Bi2Se3 hybrids is designed with artistic heteronanostructures via a hot injection in colloidal system. Interestingly, the heteronanostructures are typically constituted by single-layer Bi2Se3 hexagonal nanoplates evenly enclosed by small ultrathin hierarchical MoSe2 nanosheets on the whole surfaces. X-ray photoelectron spectroscopy investigations suggest obvious electron transfer from Bi2Se3 to MoSe2, which can help to enhance the conductivity of the hybrid electrode. Especially, schematic energy band diagrams derived from ultraviolet photoelectron spectroscopy studies indicate that Bi2Se3 has higher EF and smaller Φ than MoSe2, further confirming the electronic modulation between Bi2Se3 and MoSe2, where Bi2Se3 serves as an excellent substrate to provide electrons and acts as channels for high-rate transition. The MoSe2/Bi2Se3 hybrids demonstrating a low onset potential, small Tafel slope, high current density, and long-term stability suggest excellent hydrogen evolution reaction activity, whereas a high specific capacitance, satisfactory rate capability, and rapid ions diffusion indicate enhanced supercapacitor performance. [ABSTRACT FROM AUTHOR]

Let be an integral domain, and the set of fractional ideals of . Let a finitely generated ideal with . For a torsion-free -module , define for some . Call a -module if . On , the function is a star-operation of finite character. An integral ideal maximal with respect to being a proper -ideal is a prime ideal called a maximal -ideal. A torsion-free -module is called -flat, if is a flat -module for each , the set of maximal -ideals of . is called a Prüfer -multiplication domain (PMD), if is a valuation ring for each . We characterize -flat modules in a manner similar to the characterization of flat modules, study them when they are rings with and characterize PMDs using them and compare our work with similar work in the literature. [ABSTRACT FROM AUTHOR]