A single image dehazing model using total variation and inter-channel correlation

Outdoor images are often degraded by haze, causing a change of image contrast and color values. In this paper, we propose a novel variational model for the removal of haze in a single color image, by incorporating an inter-channel correlation term into the total variation based model in Wang et al. (Pattern Recognit 80:196–209, 2018). The proposed model enables both color and gray-valued transmission maps, contributing to its broad applications, and its convergence analysis is also provided. To realize the proposed model, we adopt an alternating minimization algorithm, and then the alternating direction method of multipliers is employed for solving subproblems. These result in an efficient iterative algorithm, with its convergence proven. Numerical experiments validate the outstanding performance of the proposed model compared to the state-of-the-art methods.

     

A Bit-Error Rate Measurement and Error Analysis of Wireline Data Transmission using Current Source Model for Single Event Effect under Irradiation Environment

A high-speed wireline interfaces, e.g. LVDS (Low Voltage Differential Signaling), are widely used in the aerospace field for powerful computing in artificial satellites and aircraft [19]. This paper describes Bit Error Rate (BER) prediction methodology for wireline data transmission under irradiation environment at the design stage of data transmitter, which is useful in proactively determining if the design circuit meets the BER criteria of the target system. Using a custom-designed LVDS transmitter (TX) to enhance latch-up immunity [42], the relationship between transistor size and BER has been analyzed with focusing on Single Event Effect (SEE) as a cause of the bit error. The measurement was executed under ⁸⁴Kr¹⁷⁺ exposure of 322.0 MeV at various flux condition from 1?×?10³ to 5?×?10⁵ count/cm²/sec using cyclotron facility. For the analysis of the bit error, circuit simulation by SPICE was utilized with expressing the irradiation environment by a current source model. The current source model represents a single event strike into the circuit at drain and substrate junctions in bulk MOSFETs. For the construction of the current source model, a charge collection was simulated at the single particle strike with the creation of 3D Technology CAD (TCAD) models for the MOS devices of bulk transistor process technology. The simulation result of the charge correction was converted to a simple time-domain equation, and the single-event current source model was produced using the equation. The single-event current source was applied to SPICE simulation at bias current related circuits in the LVDS transmitter, then simulation results are carefully verified whether the output data is disturbed enough to cause bit errors on wireline data transmission. By the simulation, sensitive MOSFETs have been specified and a sum of the gate area for these MOSFETs has 29% better correlation than the normal evaluation index (sum of the drain area) by comparison to the actual BER measurement. Through the precise revelation of the sensitive area by SPICE simulation using the current model, it became possible to estimate BER under irradiation environment at the pre-fabrication design stage.

     

Distributed Self-Stabilizing Capacitated Maximal Independent Set Construction in Wireless Sensor Networks

Wireless sensor networks (WSNs) are composed of a large number of wireless self-organized sensor nodes connected through a wireless decentralized distributed network without the aid of a predefined infrastructure. Fault-tolerance and power management are fundamental challenges in WSNs. A WSN is self-stabilizing if it can initially start at any state and obtain a legitimate state in a finite time without any external intervention. Self-stabilization is an important method for providing fault-tolerance in WSNs. Maximal independent set (MIS) is an extensively used structure for many important applications such as clustering (Randhawa and Jain in Wirel Personal Commun 97(3):3355, 2017. https://doi.org/10.1007/s11277-017-4674-5) and routing (Attea et al. in Wirel Personal Commun 81(2):819, 2015. https://doi.org/10.1007/s11277-014-2159-3; Lipiński in Wirel Personal Commun 101(1):251, 2018. https://doi.org/10.1007/s11277-018-5686-5) in WSNs. The capacitated MIS (CapMIS) problem is an extension of MIS in that each node has a capacity that determines the number of nodes it may dominate. In this paper, we propose a distributed self-stabilizing capacitated maximal independent set algorithm (CapMIS) in order to reduce energy consumption and support load balancing in WSNs. To the best of our knowledge, this is the first algorithm in this manner. The algorithm is validated through theoretical analysis as well as testbed implementations and simulations.

     

Minimized SER and QOS Based Power Allocation Strategies for Multi HDAF Relay Cooperative Network

In this paper, a multi hybrid decode-amplify-forward relay cooperative network with perfect CSI in flat Rayleigh fading channel is considered. Using moment generating function based approach, the closed form of symbol error rate (SER) with asymptotic approximation is derived. Based on the lower bound of SER (Olfat and Olfat in IET Commun 5(4):2018–2027, 2011), Lagrange multiplier method and differential evolution (DE) algorithm based power allocation schemes are proposed. With fixed source power, the relay powers are optimized with the proposed schemes by the power allocation factor. Further the SER performance of proposed power allocation schemes is investigated by varying the location of the relays. The performance gain of proposed power allocation schemes depends on the channel quality of source to relay and relay to destination links. It is observed that the proposed power allocation schemes outperform the equal power allocation scheme and DE based power allocation provides SER response close to power allocation with Lagrange multiplier method. In order to achieve the target SER (quality of service) minimum power allocation is introduced as minimum relay power allocation and minimum source and relay power allocation.

     

Design of 2.4 GHz Improved Current Reuse Gilbert Mixer with Source Degeneration Technique

An improved Gilbert mixer with the current reuse and source degeneration techniques is investigated. This design and simulation carried out by considering UMC 180 nm CMOS process in the Cadence Tool 6.1.6 with 2.4 GHz. The investigation is presented with the current reuse topology by stacking both pMOS and nMOS transistors. The reduction of the power consumption is obtained due to the self-biasing of the shunt feedback resistor. An improvement in the conversion gain and linearity is shown through the source degeneration in this mixer design. The proposed design achieves the maximum conversion gain (CG) of 13.2 dB with the noise figure (NF) of 8.6 dB. The design circuit consumes 0.7 mW power from 1.2 V with the 1 dB compression point of ?2.63 dBm and third-order input intercept point (IIP3) of 8.2 dBm. The chip area occupied is 0.128?×?0.180 mm² shown in the layout design. This compact layout of the mixer helps to create an opportunity as a suitable building block for RF integrated circuit (RFIC) applications with moderately high performance in the receiver front end.

Graphic Abstract

     

Recent Developments in Spatio-Temporal EEG Source Reconstruction Techniques

EEG is gaining recognition in the field of real-time applications. However, the EEG inverse problem leads to poor spatial resolution in brain source localization. This paper presents an overview of the existing EEG inverse solution methods. Further, a comparative analysis of recent techniques has been presented. This work discusses the challenges associated with the existing source reconstruction algorithms. The main focus is on the recent reports in this field that have combined the EEG denoising in the pre-processing phase along with the inverse localization approaches. Out of various existing techniques, SLORETA offers better localization results but its noise sensitivity is very high. It has been validated in a comparative analysis for simulated dipole sources with no noise. To illustrate the advantage of using pre-processed data with inverse localization, the classification accuracy of conventional methods has been compared. The accuracy has been analyzed for depression signals using the Naïve Bayes, RF, and SVM classifiers. The VMD- SLORETA method shows better accuracy as compared to EMD-SLORETA and SLORETA only. The existing EEG localization methods are efficient but the spatial resolution is still to be improved in the presence of various noise sources in raw EEG. More accurate localization is achieved by implementing denoising in combination with the source localization framework. There is a need to investigate further stages of EEG signal processing along with optimal feature selection. Further, additional studies should be conducted to improve the noise sensitivity of other existing localization systems using pre-processing approaches.

Graphic Abstract

     

EMGGR: an energy-efficient multipath grid-based geographic routing protocol for underwater wireless sensor networks

Routing in underwater wireless sensor networks (UWSN) is an important and a challenging activity due to the nature of acoustic channels and to the harsh environment. This paper extends our previous work [Al-Salti et al. in Proceedings of cyber-enabled distributed computing and knowledge discovery (CyberC), Shanghai, pp 331–336, 2014] that proposed a novel multipath grid-based geographical routing (MGGR) protocol for UWSNs. The extended work, EMGGR, viewed the network as logical 3D grids. Routing is performed in a grid-by-grid manner via gateways that use disjoint paths to relay data packets to the sink node. The algorithm consists of three main components: (1) a gateway election algorithm; responsible for electing gateways based on their locations and remaining energy level (2) a mechanism for updating neighboring gateways’ information; allowing sensor nodes to memorize gateways in local and neighboring cells, and (3) a packet forwarding mechanism; in charge of constructing disjoint paths from source cells to destination cells, forwarding packets to the destination and dealing with holes (i.e. cells with no gateways) in the network. The performance of EMGGR has been assessed using Aqua-Sim, which is an NS2 based simulator for UWSNs. Results show that EMGGR is an energy efficient protocol in all simulation setups used in the study. Moreover, EMGGR can also maintain good delivery ratio and end-to-end delay.

     

Security Flaws in a Smart Card Based Authentication Scheme for Multi-server Environment

Recently, Wang and Ma (Wireless Pers Commun, 2012. doi:10.1007/s11277-011-0456-7) proposed a smart card based authentication scheme for multi-server environment. They also demonstrated that their scheme could overcome various attacks. In this paper, the security of Wang et al.’s scheme is evaluated. Our analysis shows their scheme is vulnerable to the server spoofing attack, the impersonation attack, the privileged insider attack and the off-line password guessing attack.     

A novel weight based clustering algorithm for routing in MANET

Cluster based routing in Mobile AdHoc Networks are considered one of the convenient method of routing. Existence of Cluster Head (CH) in a group of nodes for data forwarding improves the performance of routing in terms of routing overhead and power consumption. However, due to the movement of CH and frequent change in cluster members, cluster reformation is required and increases cluster formation overhead. The stability of the cluster highly dependent of stability of the CH and hence during CH selection special care should be taken so that the cluster head survives for longer time. In this paper a method of cluster formation is proposed which will take into account two most vital factor node degree and bandwidth requirement for construction of the cluster and selection of the cluster head. Further, when two clusters come closer to each other they merge and form a single cluster. In such case out of two CHs one has to withdraw the role and other will take over. A new mechanism of merging two clusters is also proposed in the paper. We call this method as an Improved Cluster Maintenance Scheme and primarily focused on minimizing CH changing process in order to enhance the performance. The stated method makes cluster more stable, and minimizes packet loss. The proposed algorithm is simulated in ns-2 and compared with Least Cluster head Change (LCC) and CBRP. Our algorithm shows better behavior in terms of number of clusterhead changes or number of cluster member changes.     

Cryptanalysis and Improvement of a Robust Smart Card Authentication Scheme for Multi-server Architecture

A multi-server authentication scheme enables a remote user to access the services provided by multiple servers after registering with the registration center. Recently, Pippal et al. (Wirel Pers Commun 2013, doi:10.1007/s11277-013-1039-6) introduced a robust smart card authentication scheme for multi-server architecture. They also illustrated that their scheme could be free from potential network attacks, and validated the scheme by using BAN logic. In this paper, by presenting concrete attacks, we demonstrate that Pippal et al.’s scheme can not withstand off-line password guessing attacks, impersonation attacks and privileged insider attacks. Furthermore, to overcome these attacks, we propose an improved authentication scheme for multi-server architecture using smart card and password. Security and efficiency analysis indicates that our scheme not only actually achieves intended security goals (e.g., two-factor authentication, perfect forward secrecy etc.), but also is efficient enough to be implemented for practical applications.     

Optimized and Dynamic Selection of Cluster Head Using Energy Efficient Routing Protocol in WSN

Wireless Personal Communications - Wireless Sensor Networks plays an outstanding role in providing dynamic cluster head (CH) selection. However, the selection of CH is a major challenge due to...     

Simplified weighted least squares design of 2-D FIR digital filters

A simple easy to use and very flexible approach is presented for the design of 2-D fir digital filters. It is illustrated by two examples, a rectangular filter and a diamond filter. Appropriate selection of the weighting function which is used in the weighted least squares method can yield very diverse characteristics, like the possibility to meet specifications on both frequency response and step response.     

Exploiting W. Ellison model for seawater communication at gigahertz frequencies based on world ocean atlas data

Electromagnetic (EM) waves used to send signals under seawater are normally restricted to low frequencies () because of sudden exponential increases of attenuation () at higher . The mathematics of EM wave propagation in seawater demonstrate dependence on relative permeability (), relative permittivity (), conductivity (), and of transmission. Estimation of and based on the W. Ellison interpolation model was performed for averaged real‐time data of temperature () and salinity () from 1955 to 2012 for all oceans with latitude/longitude points and 101 depth points up to 5500 m. Estimation of parameters such as real and imaginary parts of , , , , loss tangent (tan ), propagation velocity (), phase constant (), and contributes to absorption loss () for seawater channels carried out by using normal distribution fit in the 3 GHz–40 GHz range. We also estimated total path loss () in seawater for given transmission power and antenna (dipole) gain. MATLAB is the simulation tool used for analysis.