Certificateless Signature Scheme Based on Rabin Algorithm and Discrete Logarithm

Certificateless signature can effectively immue the key escrow problem in the identity-based signature scheme. But the security of the most certificateless signatures usually depends on only one mathematical hard problem, which makes the signature vulnerable when the underlying hard problem has been broken. In order to strengthen the security, in this paper, a certificateless signature whose security depends on two mathematical hard problems, discrete logarithm and factoring problems, is proposed. Then, the proposed certificateless signature can be proved secure in the random oracle, and only both of the two mathematical hard problems are solved, can the proposed signature be broken. As a consequence, the proposed certificateless signature is more secure than the previous signatures. On the other hand, with the pre-computation of the exponential modular computation, it will save more time in the signature signing phase. And compared with the other schemes of this kind, the proposed scheme is more efficient

Summer moisture changes in the Lake Qinghai area on the northeastern Tibetan Plateau recorded from a meadow section over the past 8400 yrs

Holocene climatic and environmental changes on the northeastern Tibetan Plateau (TP) have been widely discussed based on the climatic records from sedimentary cores. However, differences in the reconstructed climatic history from various studies in this region still exist, probably due to influence of climatic proxies from multiple factors and the chronological uncertainties in lacustrine sediments. Here we present records of terrestrial plant delta C-13, soil color and total organic carbon content over the past 8400 years from a well-dated meadow section on the northeastern TP. The terrestrial plant delta C-13 value serves as a good summer precipitation/moisture indicator in the studied region. Soil color property and TOC content are also able to disentangle the moisture evolution history. All the data show much wet climates at 8400-7400 cal yr BP, dry climates at 7400-6000 cal yr BP and then wet conditions with fluctuation at 6000-3200 cal yr BP. Late Holocene moisture appears to be comparable with moist conditions from 6000 to 3200 cal yr BP. By further comparing the climatic variations in the Lake Qinghai area with records of the reconstructed summer temperature and the Asian Monsoon precipitation, we believe that the pattern of moisture/precipitation evolution in the Lake Qinghai area was not completely consistent with regions around Lake Qinghai, probably due to complicated interaction between the East Asian Summer Monsoon and the Indian Summer Monsoon

Robust generalized filter bank multicarrier based optical access system with electrical polar coding

A robust generalized filter bank multicarrier (GFBMC) optical access system with polar coding is proposed in the letter. Cyclic redundancy check combined polar code has been adopted to improve the performance of the access system with lower computational time. An experiment with a 40 Gb/s polar coded GFBMC access system is successfully demonstrated with the proposed method. The results indicate a prospect solution for the forward error correction (FEC) in optical access system

Security analysis on an electronic voting scheme based on a quantum ring signature

Recently, Qiu et al. proposed a quantum voting scheme based on the ring signature (International Journal of Theoretical Physics, 60: 1550–1555(2021)), in which the signer and verifier only need measure the received particles with Z-basis and perform some classical simple encryption/decryption operations on the classical message. Although their scheme is very efficient, it cannot resist against the eavesdropping attacks and forgery attack. In this paper, first, the eavesdropping attacks on Qiu et al.’s scheme are proposed. Second, we show the forgery attack on their scheme. According to the security analysis, it follows that, when desiring the quantum ring signature scheme, we should carefully analysis its security against eavesdropping attacks and forgery under chosen message attack

Underwater broadband acoustic scattering modelling based on FDTD

A modified finite-difference time-domain (FDTD) method is described in this paper. The absorption coefficient which is frequency-dependent is considered, and it is used to compute broadband acoustic scattering model of underwater complex object. The perfectly matched layer (PML) absorbing boundary condition (ABC) is applied to this work. Considering computation and accuracy comprehensively, PML boundary layer number and the attenuation coefficient is set at proper values. Computer Graphics are applied to mesh-generating of the irregular object. A pulse of LFM signal is used to simulate wide-band acoustic scattering field of a circle in 2D and a complex object in 3D. And the scattered acoustic pressure waveforms of some certain points are computed in the calculation field. Results obtained from simulation confirm the high accuracy of the proposed method.This research was supported in part by the Foundation of Key Laboratory of China’s Education Ministry and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.http://www.eejournal.ktu.lt/index.php/eltam201

Modeling of nonlinear system based on deep learning framework

A novel modeling based on deep learning framework which can exactly manifest the characteristics of nonlinear system is proposed in this paper. Specifically, a Deep Reconstruction Model (DRM) is defined integrating with the advantages of the deep learning and Elman neural network (ENN). The parameters of the model are initialized by performing unsupervised pretraining in a layer-wise fashion using Restricted Boltzmann Machines (RBMs) to provide a faster convergence rate for modeling. ENN can be used to manifest the memory effect of system. To validate the proposed approach, two different nonlinear systems are used for experiments. The first one corresponds to the Class-D power amplifier (CDPA) which operates in the ohmic and cut-off regions. According to error of time domain and spectrum, Back Propagation Neural Network model improved by RBMs (BP-RBMs) and ENN are compared of different input signals which are the simulated two-tone signal and actual square wave signal. The second system is a permanent magnet synchronous motor (PMSM) servo control system based on fuzzy PID control strategy. In terms of simulated and actual speed curves, BP-RBMs, DRM and ENN model are adopted on comparison respectively. It is shown by experimental results that the proposed model with fewer parameters and iteration number can reconstruct the nonlinear system accurately, and depict the memory effect, the nonlinear distortion and the dynamic performance of system precisely.This work was supported in part by the Foundation of Key Laboratory of China’s Education Ministry and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.http://link.springer.com/journal/110712017-05-31hb2016Electrical, Electronic and Computer Engineerin

Robust Super-Resolution Imaging Based on a Ring Core Fiber with Orbital Angular Momentum

Single fiber imaging technology offers unique insights for research and inspection in difficult to reach and narrow spaces. In particular, ultra-compact multimode fiber (MMF) imaging, has received increasing interest over the past decade. However, MMF imaging will be seriously distorted when subjected to dynamic perturbations due to time-varying mode coupling, and the imaging of space objects via Gaussian beam will be relatively degraded at the edge due to insufficient contrast. Here, a robust super-resolution imaging method based on a ring core fiber (RCF) with orbital angular momentum (OAM) has been proposed and experimentally demonstrated. The OAM modes propagating in the RCF form a series of weakly-coupled mode groups, making our imaging system robust to external perturbations. In addition, a spiral phase plate is used as a vortex filter to produce OAM for edge enhancement, thus improving the image resolution. Furthermore, a few-shot U-Transformer neural network is proposed to enhance the resilience of the developed RCF-OAM imaging system against environmental perturbations. Finally, the developed RCF-OAM imaging system achieves biological image transmission, demonstrating the practicality of our scheme. This pioneering RCF OAM imaging system may have broad applications, potentially revolutionising fields such as biological imaging and industrial non-destructive testing

Peak-to-average power ratio reduction for DCO-OFDM underwater optical wireless communication system based on an interleaving technique

In underwater direct current-biased optical orthogonal frequency-division multiplexing (DCO-OFDM) system, high peak-to-average power ratio (PAPR) brings in-band distortion and out-of-band power. It also decreases the signal-to-quantization noise ratio of the analog-to-digital converter and the digital-to-analog converter. A time–frequency-domain interleaved subbanding scheme is proposed to reduce the PAPR of underwater DCO-OFDM system with low computation complexity and bit error rate (BER). The system BER is evaluated by the distances of the underwater optical wireless communication (UOWC), as well as by the signal attenuation of the UOWC channel. A least-square channel estimation method is adopted for adaptive power amplification at the receiver side, to further decrease the system BER

Hollow core fiber based interferometer for high temperature (1000 °C) measurement

A simple, cost effective high temperature sensor (up to 1000 °C) based on a hollow core fiber (HCF) structure is reported. It is configured by fusion splicing a short section of HCF with a length of few millimeters between two standard single mode fibers (SMF-28). Due to multiple beam interference introduced by the cladding of the HCF, periodic transmission dips with high spectral extinction ratio and high quality (Q) factor are excited. However, theoretical analysis shows that minor variations of the HCF cladding diameter may result in a significant decrease in the Q factor. Experimental results demonstrate that the position of periodic transmission dips are independent of the HCF length, but spectral Q factors and transmission power varies with different HCF lengths. A maximum Q factor of 3.3×104 has been demonstrated with large free spectral range of 23 nm and extinction ratio of 26 dB. Furthermore, the structure is proved to be an excellent high temperature sensor with advantages of high sensitivity (up to 33.4 pm/°C), wide working temperature range (from room temperature to 1000°C), high resolution, good stability, repeatability, relatively low strain sensitivity (0.46 pm/με), low cost and a simple and flexible fabrication process that offers a great potential for practical applications. A thorough theoretic analysis of the HCF based fiber structure has been proposed. The experimental results are demonstrated to be well matched with our simulation results