The cyclic stretching measurements in various geometries including uniaxial, planar, unequal, and equal biaxial extension reveal the distinctive features of the internal fracture in the double ...network (DN) hydrogels with high toughness, which are composed of the rigid and brittle first network and the soft and ductile second network. The initial modulus, residual strain after unloading, dissipated energy (D), dissipation factor (Δ; the ratio of D to input strain energy), and the ultimate elongation of network strands (λi,m*) in each loading–unloading cycle are evaluated as a function of the imposed maximum elongation in the i-direction (λ i,m, i = x, y) in each cycle. The modulus reduction and Δ depend on the stretching mode when compared at the same λ i,m, but each of them exhibits a universal relation independently of the stretching mode when the corresponding magnitude of the deformation tensor (m m; m m = (I 1,m 2 – 2I 2,m)1/2 where I 1,m = λ x,m 2 + λ y,m 2 + λ z,m 2 and I 2,m = λ x,m 2λ y,m 2 + λ y,m 2λ z,m 2 + λ z,m 2λ x,m 2) is used as a variable. This is in contrast to that Δ of the filler-reinforced elastomers, which undergo apparently similar mechanical hysteresis, which shows the corresponding universal relation using I 1,m as a variable. The difference in governing variable indicates that the influence of the cross-effect of strains (λ i λ j ; i,j = x,y,z and i ≠ j) on Δ is pronounced in the DN gels whereas it is minimal in the filled elastomers. Characteristically, λ i,m* is close to λ i,m in every type of deformation, indicating that in the end of the loading most of the chains with lower extensibility than λ i,m undergo fracture whereas most of the long chains with higher extensibility than λ i,m remain intact. The elongation λ i,m* has no appreciable cross-effect of strains in contrast to the modulus reduction as well as Δ.
This paper experimentally investigates a direction of arrival (DOA)-based wave source location estimation method for spectrum sharing in millimeter-wave band local and private fifth-generation (5G) ...mobile communication systems. In the DOA-based wave source location estimation, it is important to extract a line-of-sight (LOS) component from the received signals. Considering that in 5G systems, synchronization signal / physical broadcast channel (SS/PBCH) blocks are transmitted with beam-sweeping for initial access, our measurement system performs the DOA estimation based on the maximum-power block where the LOS component seems to be dominant. In the DOA estimation, taking advantage of the sparsity of the propagation channels in both angular space and delay time domains, our measurement system adopts the compressed sensing (CS)-based approach. As for the measurement antenna, a directional pattern is employed, which enables the estimation with only four antenna elements. We experimentally demonstrate the performance of the wave source location estimation in an outdoor environment using a commercial 28 GHz-band 5G base station (BS). Experimental results show that our measurement system achieves a location estimation error of 5.8 m based on 20 measurements.
Deniable ring authentication enables a prover in some group (called a
ring
) to authenticate a message to a verifier using its secret key while at the same time allowing the prover to deny ever ...having interacted with the verifier. This primitive furthermore guarantees the anonymity of the prover in the sense that the verifier will learn nothing about the prover’s identity except that it is included in the ring. In this work, we propose a new generic construction of two-round concurrently deniable ring authentication in the random oracle model. Our generic construction is based on any
IND-CPA
secure broadcast encryption (BE) scheme. Instantiating the underlying
IND-CPA
secure BE scheme with the schemes proposed by Agrawal and Yamada (EUROCRYPT 2020) or Agrawal, Wichs, and Yamada (TCC 2020), we obtain the first two-round concurrently deniable ring authentication scheme with optimal efficiency in an asymptotic sense. Here, by optimal efficiency, we mean that all of the sizes of a public parameter and secret keys, the communication costs, and the number of pairing operations are independent of
n
, where
n
is the number of users in a ring. In addition to these main instantiations, through our generic construction, we further obtain various two-round concurrently deniable ring authentication schemes.
In this paper, we propose an uplink multiuser-multiple input multiple output (MU-MIMO) cooperative retransmission control scheme for the reliable and efficient communication of autonomous unmanned ...aerial vehicles (i.e., flight communication and drone-to-drone communication). This scheme is a key element in the design of a drone-based ad-hoc network. Because drone relay transmission operates in the air, flexible wireless relay networks over large areas can be achieved without interference from multipath signals caused by buildings and obstacles in ground-based communication. However, two main challenges exist. First, the relay transmission system occupies bandwidth every time the drone relays information. Therefore, because the radio channel is shared by multiple relay stations, the throughput is greatly reduced. To improve throughput, it is better to transmit using the minimum number of relay stations. Ultimately, long-distance direct transmission is the best. The other issue is a direct result of the first issues solution: the propagation loss increase when relaying information directly over a long distance. Moreover, because the frequency of interference waves from the ground increases, transmission signal errors are an important issue. To solve this issue, a transmission scheme to reduce errors is required. The scheme proposed in this study achieves high transmission reliability and efficiency even under high transmission error conditions. The results of a computer simulation reveal that the proposed method achieves a direct transmission throughput that is 1.5 times better than that of a conventional scheme. It is also shown that the proposed scheme requires only about three stations to achieve acceptable results.
•Build a small scale and a large scale sketch-based 3D model retrieval benchmark.•Evaluate 15 best sketch-based 3D model retrieval algorithms on the two benchmarks.•Solicit and identify the ...state-of-the-art methods and promising related techniques.•Incisive analysis on diverse methods w.r.t scalability and efficiency performance.•The benchmarks and evaluation tools provide good reference to the related community.
Sketch-based 3D shape retrieval has become an important research topic in content-based 3D object retrieval. To foster this research area, two Shape Retrieval Contest (SHREC) tracks on this topic have been organized by us in 2012 and 2013 based on a small-scale and large-scale benchmarks, respectively. Six and five (nine in total) distinct sketch-based 3D shape retrieval methods have competed each other in these two contests, respectively. To measure and compare the performance of the top participating and other existing promising sketch-based 3D shape retrieval methods and solicit the state-of-the-art approaches, we perform a more comprehensive comparison of fifteen best (four top participating algorithms and eleven additional state-of-the-art methods) retrieval methods by completing the evaluation of each method on both benchmarks. The benchmarks, results, and evaluation tools for the two tracks are publicly available on our websites 1,2.
In the situation where there are one sender and multiple receivers, a receiver selective opening (RSO) attack for an identity-based encryption (IBE) scheme considers adversaries that can corrupt some ...of the receivers and get their user secret keys and plaintexts. Security against RSO attacks for an IBE scheme ensures confidentiality of ciphertexts of uncorrupted receivers. In this paper, we formalize a definition of RSO security against chosen ciphertext attacks (RSO-CCA security) for IBE and propose the first RSO-CCA secure IBE schemes. More specifically, we construct an RSO-CCA secure IBE scheme based on an IND-ID-CPA secure IBE scheme and a non-interactive zero-knowledge proof system with unbounded simulation soundness and multi-theorem zero-knowledge. Through our generic construction, we obtain the first pairing-based and lattice-based RSO-CCA secure IBE schemes.
In this paper, we construct multi-key homomorphic and fully homomorphic encryption (resp. MKHE and MKFHE) schemes with malicious circuit privacy. Our schemes are based on learning with errors (LWE) ...besides appropriate circular security assumptions. In contrast, the previous maliciously circuit-private MKFHE scheme by Chongchitmate and Ostrovsky (PKC, 2017) is based on the non-standard decisional small polynomial ratio (DSPR) assumption with a super-polynomial modulus, besides ring learning with errors and circular security assumptions. We note that it was shown by Albrecht et al. (CRYPTO, 2016) that there exists a sub-exponential time attack against this type of DSPR assumption. The main building block of our maliciously circuit-private MKFHE scheme is a (plain) MKFHE scheme by Brakerski et al. (TCC, 2017), and the security of our schemes is proven under the hardness of LWE with sub-exponential modulus-to-noise ratio and circular security assumptions related to the Brakerski et al. scheme. Furthermore, based on our MKFHE schemes, we construct four-round multi-party computation (MPC) protocols with circuit privacy against a semi-honest server and malicious clients in the plain model. The protocols are obtained by combining our schemes with a maliciously sender-private oblivious transfer protocol and a circuit garbling scheme, all of which can be instantiated only assuming LWE.
In greenhouse tomato cultivation, three primary methods of flower pollination exist: insect pollination, physical pollination by vibrating flowers, and artificial pollination using hormone-based ...chemicals. Insect pollination, the natural method, involves insects (e.g., honeybees) vibrating flowers to collect pollen and nectar. This paper proposes an alternate approach, using small drones to search and pollinate flowers in place of bees autonomously. We report field experiments conducted using these drone technologies. The drone must locate flowers ready for pollination. We developed an artificial intelligence (AI) image classification system (AI classifier) using machine learning to identify these flowers. Equipped with an AI classifier, the drone searches for flowers through autonomous flight and positioning technology. Upon identifying a suitable flower during its search, the drone makes contact to pollinate it. Integrating AI-based flower detection, autonomous flight control for flower search, and a pollination control device allows the drone to perform pollination. This study devises these technologies, implements them in a drone, and evaluates their effectiveness through a pollination experiment.
Anisotropy of strain-induced internal damage in tough double network (DN) hydrogels is characterized by a sequence of two tensile experiments. Firstly, the virgin DN gels are subjected to a single ...biaxial loading-unloading cycle using various combinations of the two maximum strains
λ
x
,m
and
λ
y
,m
in the
x
- and
y
-directions (
λ
x
,m
≥
λ
y
,m
). Secondly, the rectangular subsamples, which are cut out from the unloaded specimens so that the long axis can have an angle (
) relative to the larger pre-strain (
x
-)axis, are stretched uniaxially along the long axis. Directional internal damage caused by various types of pre-stretching is evaluated by comparing the loading curves of the virgin gels and the subsamples with various
. The modulus reduction (Δ
E
) and strain-energy reduction (
D
) are characterized as functions of
λ
x
,m
,
λ
y
,m
and
. The anisotropy of damage increases with the anisotropy of imposed pre-strain field as well as
λ
x
,m
, which is also observed in the anisotropic re-swelling behavior of the subsamples. The damage and the extensibility of the subsamples with
= 0° increase with
λ
y
,m
, and the damage of the subsamples with
= 90° significantly increases with
λ
x
,m
. These results reveal the presence of a pronounced damage cross-effect: a finite portion of the chain fractures in the first brittle network in one direction is caused by loading in the other orthogonal direction. This feature is in contrast to the very modest damage cross-effect in the silica reinforced elastomers, which show apparently similar stress-softening behavior but with a different origin. The strong damage cross-effect is a key feature of the internal fracture mechanism of the tough DN gels.
Anisotropy of strain-induced internal damage in tough double network (DN) hydrogels is characterized by a sequence of two tensile experiments.
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