Narrow Results

This paper describes a hierarchical controlled quantum teleportation scheme of arbitrary two-qubit based on an eight-particle maximum entanglement state among four parties, one sender and three receivers. In order to prevent the infidelity of the receivers, secret state will be purposefully split and sent to the three receivers. According to the noncloning theorem, only one of the three receivers can recover secret state and the high authorized receiver that recovers the information only requires the cooperation of one of the remaining two receivers. On the contrary, the low authorized party that recovers the secret state requires the cooperation of all remaining receivers.

A novel structure resembling plant stems, termed bio-inspired fractal plant stems multi-cellular circular tubes (BFPMC), was developed by incorporating fractal plant stem characteristics into smaller circular tubes within larger ones. The crashworthiness of this structure under axial impact was investigated using a validated LS-DYNA finite element model. The energy absorption performance of BFPMC tubes, varying in the number of branches, fractal orders, and inner circular diameters, was numerically studied. The numerical findings reveal a 19.27% increase in specific energy absorption (SEA) for BFPMC with $D_i=30$mm compared to $D_i=0$mm, indicating that filling a single circular tube can enhance the structure’s impact resistance. Subsequently, structural parameters conducive to excellent energy absorption characteristics were determined for various combinations of a number of branches, fractal order, and inner circle diameter parameters. These results offer valuable insights for designing multi-cellular double tubes with high energy absorption efficiency.

The ability to obtain complex global behaviour from simple local rules makes cellular automata an interesting platform for massively parallel computation. However, manually designing a cellular automaton to perform a given computation can be extremely difficult, and automated design techniques such as genetic programming have their limitations because of the absence of human intuition. In this paper, we propose elements of a framework whose goal is to make the manual synthesis of cellular automata rules exhibiting desired global characteristics more programmer-friendly, while maintaining the simplicity of local processing elements. Although many of the framework elements that we describe here are not new, we group them into a consistent framework and show that they can all be implemented on a traditional cellular automaton, which means that they are merely more human-friendly ways of describing simple cellular automata rules, and not foreign structures that require changing the traditional cellular automaton model.

High porosity $\alpha$-Fe₂O₃ has attracted a lot of attention due to its exceptional structure. In this paper, nanoflake assembled hierarchical porous flower-like $\alpha$-Fe₂O₃ was prepared by hydrothermal and calcination methods without any additional templates. Scanning electron microscopy (SEM) morphological characterization results show that with the increase of calcination temperature (400^∘C, 450^∘C, 500^∘C, 550^∘C, 600^∘C), pores appeared. However, the results of nitrogen adsorption show that the specific surface area of the $\alpha$-Fe₂O₃ reaches the maximum value (52.19m²/g) when the calcination temperature is 500^∘C. The gas sensing performance of flower-like $\alpha$-Fe₂O₃ with different calcination temperature is compared, interestingly, with the increase of calcination temperature, the response of the samples increased first and then decreased, and reached the maximum value (44.2–100 parts per million (ppm) acetone) when the calcination temperature was 500^∘C. The minimum concentration for acetone was 200 ppb (response value is 2.0). Moreover, calcined at 500^∘C, hierarchical porous $\alpha$-Fe₂O₃ has a fast response recovery (4/25 s) and low working temperature (210^∘C). These excellent gas sensing properties are mainly due to porous structure, large specific surface area, and oxygen vacancies on the surface, which make it a promising material for acetone sensors.

Object-based storage is a kind of cloud storage technology, with better data sharing, better security, better intelligence. Mass storage system consists of thousands of devices, and gradually extended to form, therefore, the data placement is one of the key problems in the efficient organization of storage devices. Although consistent hashing has the good adaptability, but it need to increase the number of virtual nodes in heterogeneous environment. This paper introduces the hierarchical data placement algorithm, and improves the consistent hashing and improves the setting weight method and the clustering method.

In a proxy re-encryption scheme, a semi-trusted proxy converts a ciphertext for Alice into a ciphertext for Bob without seeing the underlying plaintext. A number of solutions have been proposed in public key settings. Hierarchical identity-based cryptography is a generalization of identity-based encryption that mirrors an organizational hierarchy, which allows a root private key generator to distribute the workload by delegating private key generation and identity authentication to lower-level private key generators. In this paper, we propose a hierarchical identity-based proxy re-encryption (HIBPRE) scheme which achieves IND-PrID-CCA2 security without random oracles. This is the first HIBPRE scheme up to now, and our scheme satisfies unidirectionality, non-interactivity and permits multiple re-encryptions.

Novel three-dimensional (3D) branched nanotubes of sodium niobate (NaNbO₃) were produced by a multi-step reaction, which involves the synthesis of Nb₂O₅ branched nanowires and subsequently treating these precursors in alkali solution. XRD and SEM have been used to analyze current products. All the obtained nanobranches exhibited tubular structure, which was induced by nanoscale Kirkendall effect and surface diffusion. This work demonstrates a simple and efficient pathway to design hierarchical and complex hollow nanostructures, which are expected to have important applications, such as sensors and photocatalysts.

This paper presents a hierarchical stereo matching strategy using the Discrete Wavelet Transform. Both area- and feature-based methods are combined into a single process by the discrete wavelet decomposition. Experiments show that the method is accurate, fast, and robust to noise.

Structural hierarchies are universal design paradigms of biological materials, e.g., several materials in nature used for carrying mechanical load or impact protection such as bone, nacre, dentin show structural design at multiple length scales from the nanoscale to the macroscale. Another example is the case of diatoms, microscopic mineralized algae with intricately patterned silica-based exoskeletons, with substructure from the nanometer to micrometer length scale. Previous studies on silica nano-honeycomb structures inspired from these diatom substructures at the nanoscale have shown a great improvement in plasticity, ductility and toughness through these designs over macroscopic silica, though along with a substantial reduction in stiffness. Here, we extend the study of these structural designs to the micron length scale by introducing additional hierarchy levels to implement a multilevel composite design. To facilitate our computational experiments we first develop a mesoscale particle-spring model description of the mechanics of bulk silica/nano-honeycomb silica composites. Our mesoscale description is directly derived from constitutive material behavior found through atomistic simulations at the nanoscale with the first principles-based ReaxFF force field, but is capable of describing deformation and failure of silica materials at tens of micrometer length scales. We create several models of randomly-dispersed fiber-composite materials with a small volume fraction of the nano-honeycomb phase, and analyze the fracture mechanics using J-integral and R-curve studies. Our simulations show a dominance of quasi-brittle fracture behavior in all cases considered. For particular materials with a small volume fraction of the nano-honeycomb phase dispersed as fibers within a bulk silica matrix, we find a large improvement (≈4.4 times) in toughness over bulk silica, while retaining the high stiffness (to 70%) of the material. The increase in toughness is observed to arise primarily from crack path deflection and crack bridging by the nano-honeycomb fibers. The first structural hierarchy at the nanometer scale (nano-honeycomb silica) provides large improvements in ductility and toughness at the cost of a large reduction in stiffness. The second structural hierarchy at the micron length scale (bulk silica/nano-honeycomb composite) recovers the stiffness of bulk silica while substantially improving its toughness. The results reported here provide direct evidence that structural hierarchies present a powerful design paradigm to obtain heightened levels of stiffness and toughness from multiscale engineering a single brittle — and by itself a functionally inferior material — without the need to introduce organic (e.g., protein) phases. Our model sets the stage for the direct simulation of multiple hierarchical levels to describe deformation and failure of complex biological composites.

Three-dimensionally hierarchical Bi₂WO₆ architectures have been produced via a facile and economical hydrothermal method without any template or surfactant. This architecture with flower-like morphology is assembled by numbers of intercrossed nanosheets. Moreover, different Bi₂WO₆ nanostructures including multilayered disks and irregular nanoplates can also be produced by simply adjusting the pH value of the precursor solution. Importantly, this kind of hierarchically structured Bi₂WO₆ architecture exhibits a much better photocatalytic activity in the photodegradation of rhodamine B than that of conventional Bi₂WO₆ multilayered disks and nanoplates. This enhanced photocatalytic performance is mainly attributed to the large specific surface areas, special structural features and high capability of absorbed oxygen species. The present work offers an effective approach for the further improvement of photocatalytic activity by designing a desirable micro/nanoarchitecture.

A hierarchical carbon material containing nanopores (micropores and mesopores) and micrometric sized capillaries (macropores) is produced using a combination of hard and soft templates. The hard template is a polypropylene (PP) cloth which decomposes during pyrolysis leaving a macroporous structure. The soft template is a cationic polyelectrolyte which stabilizes the resorcinol/formaldehyde (RF) resin porous structure during drying to give a nanoporous RF resin. The method produces a nanocomposite of the porous RF resin with an imbibed PP cloth. The composite is then pyrolyzed in a inert gas atmosphere to render a carbon material having macropores as well as micro/mesopores. The material exhibits both a large surface area (S_BET = 742 ± 2 m²/g) due to nanopores and goof fluid permeability due to micrometric sized pores. The macropores can be oriented during fabrication. The nanoporous surface can be used to support metal nanoparticles for fuel cell while the macropores allow easy flux of gas and liquids through the monolithic material.