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排序方式: 共有1546条查询结果,搜索用时 15 毫秒
1.
When applying a diagnostic technique to complex systems, whose dynamics, constraints, and environment evolve over time, being able to re-evaluate the residuals that are capable of detecting defaults and proposing the most appropriate ones can quickly prove to make sense. For this purpose, the concept of adaptive diagnosis is introduced. In this work, the contributions of information theory are investigated in order to propose a Fault-Tolerant multi-sensor data fusion framework. This work is part of studies proposing an architecture combining a stochastic filter for state estimation with a diagnostic layer with the aim of proposing a safe and accurate state estimation from potentially inconsistent or erroneous sensors measurements. From the design of the residuals, using α-Rényi Divergence (α-RD), to the optimization of the decision threshold, through the establishment of a function that is dedicated to the choice of α at each moment, we detail each step of the proposed automated decision-support framework. We also dwell on: (1) the consequences of the degree of freedom provided by this α parameter and on (2) the application-dictated policy to design the α tuning function playing on the overall performance of the system (detection rate, false alarms, and missed detection rates). Finally, we present a real application case on which this framework has been tested. The problem of multi-sensor localization, integrating sensors whose operating range is variable according to the environment crossed, is a case study to illustrate the contributions of such an approach and show the performance.  相似文献   
2.
We have theoretically investigated two-dimensional atom localization using the absorption spectra of birefringence beams of light in a single wavelength domain.The atom localization is controlled and modified through tunneling effect in a conductive chiral atomic medium with absorption spectra of birefringent beams.The significant localization peaks are investigated in the left and right circularly polarized beam.Single and double localized peaks are observed in different quadrants with minimum uncertainty and significant probability.The localized probability is modified by controlling birefringence and tunneling conditions.These results may be useful for the capability of optical microscopy and atom imaging.  相似文献   
3.
陈勇  ?吴鸣  杨军 《应用声学》2022,41(4):626-633
在户外环境中对某一目标噪声源进行声压级测量时,由于单个传声器不能在多声源干扰情况下有效监测目标信号,为了有效抑制非目标信号的干扰,通常利用传声器阵列进行波束形成从而对目标信号进行增强。MEMS传声器阵列由于体积小,价格低等优点而得到广泛使用,为了解决在户外进行噪声监测时,MEMS然而MEMS传声器阵列器件的工艺误差和灵敏度退化问题会导致波束形成滤波器的性能下降存在由器件工艺误差和老化所导致的声压级测量不准确问题,从而影响声压级的测量结果。为了解决这一问题,本文介绍了一种通过比较补偿参考传声器与传声器阵列之间的测量声压级之偏差进行从而实时在线校准的方法。该方法利用TDOA多声源定位方法在时频点上对实时采集的信号对所采集的信号在时频点上挑选有效目标信号进行有效挑选,并利用参考传声器的标准频响特性去修正阵列的声压级测量误差值。为了验证方法的可行性,本文通过实验比较了不同环境噪声干扰下的测量声压级差与无干扰条件下的测量声压级差的一致性,结果证明该校准方法在具有较好高的精确性和鲁棒性,并且可推广于任意一种阵型的传声器阵列声源定位装置噪声监测装置。  相似文献   
4.
The high-pressure structures and properties of MH2 (M = Nb, Ta) are explored through an ab initio evolutionary algorithm for crystal structure prediction and first-principles calculations. It is found that NbH2 undergoes a phase transition from a cubic Fm3¯m structure with regular NbH8 cubes to an orthorhombic Pnma structure with fascinating distorted NbH9 tetrakaidecahedrons at 48.8 GPa, while the phase transition pressure of TaH2 from a hexagonal P63mc phase with slightly distorted TaH7 decahedron to an orthorhombic Pnma phase with attractive distorted TaH9 tetrakaidecahedrons is about 90.0 GPa. Besides, the calculated electronic band structure and density of states demonstrate that all of these structures are metallic. The Poisson’s ratio, electron localization function, and Bader charge analysis suggest that these phases possess dominant ionic bonding character with the effective charges transferring from the metal atom to H. From our electron–phonon calculations, the calculated superconducting critical temperature Tc of the Pnma-NbH2 is 6.903 K at 50 GPa. Finally, via the quasi-harmonic approximation method, the phase diagrams at pressure up to 300 GPa and temperature up to 1000 K of MH2 (M = Nb, Ta) are established, where the transition pressure of Fm3¯m-NbH2 → Pnma-NbH2 and P63mc-TaH2 → Pnma-TaH2 were found to decrease with increasing temperature.  相似文献   
5.
CRANAD-2 is a fluorogenic curcumin derivative used for near-infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance of CRANAD-2 in two super-resolution imaging techniques, namely stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD-2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super-resolved image. The good performance and versatility of CRANAD-2 provides a powerful tool for near-infrared nanoscopic imaging of amyloids in vitro and in vivo.  相似文献   
6.
Herein, we propose a scheme for the realization of two-dimensional atomic localization in aλ-type three-level atomic medium such that the atom interacts with the two orthogonal standing-wave fields and a probe field. Because of the spatially dependent atom-field interaction, the information about the position of the atom can be obtained by monitoring the probe transmission spectra of the weak probe field for the first time. A single and double sharp localized peaks are observed in the one-wavelength domain. We have theoretically archived high-resolution and high-precision atomic localization within a region smaller thanλ/25×λ/25. The results may have potential applications in the field of nano-lithography and advance laser cooling technology.  相似文献   
7.
《中国物理 B》2021,30(9):97202-097202
The mobility edges and reentrant localization transitions are studied in one-dimensional dimerized lattice with nonHermitian either uniform or staggered quasiperiodic potentials.We find that the non-Hermitian uniform quasiperiodic disorder can induce an intermediate phase where the extended states coexist with the localized ones,which implies that the system has mobility edges.The localization transition is accompanied by the PT symmetry breaking transition.While if the non-Hermitian quasiperiodic disorder is staggered,we demonstrate the existence of multiple intermediate phases and multiple reentrant localization transitions based on the finite size scaling analysis.Interestingly,some already localized states will become extended states and can also be localized again for certain non-Hermitian parameters.The reentrant localization transitions are associated with the intermediate phases hosting mobility edges.Besides,we also find that the non-Hermiticity can break the reentrant localization transition where only one intermediate phase survives.More detailed information about the mobility edges and reentrant localization transitions are presented by analyzing the eigenenergy spectrum,inverse participation ratio,and normalized participation ratio.  相似文献   
8.
Titanium dioxide (TiO2) is regarded as an important prototype photocatalytic material for several decades. The charge carrier kinetics determines the photocatalytic properties of TiO2 materials; this is found to be greatly dependent on electronic structures. It has been revealed that the intrinsic intermediate gap states (intrinsic GSs) play a significant role in charge carrier kinetics that drive the photocatalytic processes of TiO2 materials, which are not well summarized until now. Motivated by this thought, the purpose of this review focuses on physiochemical science of the intrinsic GSs of TiO2 materials and their important role in charge carrier kinetics. We first give a summary on the chemical resources of the intrinsic GSs in TiO2 and their physiochemical nature. Their general energy distribution, charge carrier population, and the associated thermodynamic properties are also elaborated from an overall viewpoint. We further carefully summarize and compare the experimental studies on the energy and the density distribution of the intrinsic GSs and discuss the associated chemical resources and charge carrier localizations. Trapping is the dominant function of intrinsic GSs in the charge carrier kinetics of TiO2 materials. The significant effect of trapping on the transport, recombination, and interfacial transfer of charge carriers are also comprehensive summarized. Furthermore, the effects of charge carrier kinetics on photocatalytic performances are also discussed to some extents. Because of the importance of intrinsic GSs in modulating charge carrier kinetics, it is expected to increase the photocatalytic activity by engineering the intrinsic GSs, not only for TiO2 materials, but also for the other semiconductor photocatalysts.  相似文献   
9.
该文利用基于射线的盲解卷积方法,从直达声区的水面舰船噪声中提取出船和锚系于海底的垂直接收阵之间的时域信道响应,并利用直达波在不同阵元相对于参考阵元的到达时间差,通过序贯方法,利用射线模型和声速剖面信息,对水面舰船距接收阵的距离进行了估计。通过处理海深约为580 m的2016年美国圣巴巴拉海峡的实验数据,对1.6~3.5 km直达声区范围内Anna Maersk商船与垂直阵之间的距离进行了估计,验证了测距方法的有效性,并将结果与系统测量值和几何方法的估计值进行了比较。由于该方法不需要对海底参数进行估计,所以在海底参数未知时要优于传统匹配场方法;在声速剖面存在跃层且海底为多层分布的复杂信道条件下,该方法仍能对距离进行有效估计,且与测量值的相对误差在6%以内,小于几何方法的估计误差,测距结果精度较高。  相似文献   
10.
《Physics letters. A》2020,384(7):126152
Derived from quantum waves immersed in an Abelian gauge potential, the quasiperiodic Aubry-André-Harper (AAH) model is a simple yet powerful Hamiltonian to study the Anderson localization of ultracold atoms. Here, we investigate the localization properties of ultracold atoms in quasiperiodic optical lattices subject to a non-Abelian gauge potential, which are depicted by non-Abelian AAH models. We identify that the non-Abelian AAH models can bear the self-duality. We analyze the localization of such non-Abelian self-dual optical lattices, revealing a rich phase diagram driven by the non-Abelian gauge potential involved: a transition from a pure delocalization phase, then to coexistence phases, and finally to a pure localization phase. This is in stark contrast to the Abelian counterpart that does not support the coexistence phases. Our results establish the connection between localization and gauge symmetry, and thus comprise a new insight on the fundamental aspects of localization in quasiperiodic systems, from the perspective of non-Abelian gauge potential.  相似文献   
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