Jamming Effect Research Articles

Effect of jam and marmalade processing and storage on the phytochemical properties of currant cultivars (RibesSpp.)

In this study, changes in phytochemical properties of different currant (red, black, Ojebyn) cultivars while processing them into jam and marmalade and throughout the storage were investigated. Total phenolics content (TPC), total antioxidant capacity (TEAC and FRAP), total anthocyanins (TA), polymeric color (PC), and hydroxymethylfurfural (HMF) analyses were performed in fresh currant fruits at the beginning of the storage. Also, the same analyses were carried out on jams and marmalades at the end of 6-month storage period. Decreases were observed in TPC, TEAC, FRAP, and TA values of jam and marmalade samples of all types of currant varieties at the end of the storage. At the end of 6-month storage period, average TPC values varied between 405.74 and 657.51 μg GAE/g; TEAC values between 9.47 and 19.07 μmol TE/g; FRAP values between 7.97 and 17.44 μmol TE/g and TA values varied between 26.08 and 341.09 μg cy-3 glu/g. Novelty impact statement This study revealed that studied currant cultivars (Ribes Spp.) contain high levels of anthocyanins and other phytochemicals. Ojebyn black currant samples were determined to have the highest values among all types of currant jam and marmalade samples during storage. Overall, it is important that these highly nutritious fruits can be offered to consumers by processing them to products consumed in four seasons such as jam and marmalade.

An approximate factorization approach to multi-jammer location and range estimation from peer-to-peer connectivity measurements

The localization (i.e., location and range) of communication jammers in an area of operation of mobile agents is considered. The jammers are operated by adversaries to disrupt/jam communications among mobile agents to degrade mission performance. In comparison with prior results, we address estimation of jammer locations and ranges based purely on observed time series of peer-to-peer agent communication connectivities and corresponding agent locations. Jamming effects and communication connectivity are characterized by stochastic models. The agents are not assumed to have any additional sensors to measure received signal strength or to have any visual or other perception to “see” jammers. The fundamental algorithmic challenge is the inherent empirical ambiguity as to which agent was jammed when a loss of communication is detected. For this purpose, we develop an algorithmic framework based on approximate factorization, spatial local density-based filtering, and maximum likelihood estimation. We show efficacy of the proposed approach through simulation studies with large numbers of mobile agents in multiple simulated scenarios.

Structural complexity influences the ecosystem engineering effects of in‐stream large wood

AbstractLarge wood (LW) is an ecosystem engineer and keystone structure in river ecosystems, influencing a range of hydromorphological and ecological processes and contributing to habitat heterogeneity and ecosystem condition. LW is increasingly being used in catchment restoration, but restored LW jams have been observed to differ in physical structure to naturally occurring jams, with potential implications for restoration outcomes. This article examines the structural complexity and ecosystem engineering effects of LW jams at four sites with varying management intensity incorporating natural and restored wood. Our results reveal: (i) structural complexity and volume of jams was highest in the site with natural jams and low intensity riparian management, and lowest in the suburban site with simple restored jams; and (ii) that structural complexity influences the ecosystem engineering role of LW, with more complex jams generating the greatest effects on flow hydraulics (flow concentration, into bed flows) and sediment characteristics (D50, organic content, fine sediment retention) and the simplest flow deflector‐style restored jams having the least pronounced effects. We present a conceptual model describing a continuum of increasing jam structural complexity and associated hydromorphological effects that can be used as a basis for positioning and evaluating other sites along the management intensity spectrum to help inform restoration design and best practice.

The nascent coffee ring: how solute diffusion counters advection

We study the initial evolution of the coffee ring that is formed by the evaporation of a thin, axisymmetric, surface-tension-dominated droplet containing a dilute solute. When the solutal Péclet number is large, we show that diffusion close to the droplet contact line controls the coffee-ring structure in the initial stages of evaporation. We perform a systematic matched asymptotic analysis for two evaporation models – a simple, non-equilibrium, one-sided model (in which the evaporative flux is taken to be constant across the droplet surface) and a vapour-diffusion limited model (in which the evaporative flux is singular at the contact line) – valid during the early stages in which the solute remains dilute. We call this the ‘nascent coffee ring’ and describe the evolution of its features, including the size and location of the peak concentration and a measure of the width of the ring. Moreover, we use the asymptotic results to investigate when the assumption of a dilute solute breaks down and the effects of finite particle size and jamming are expected to become important. In particular, we illustrate the limited validity of this model in the diffusive evaporative flux regime.

Securing Wireless Transmissions With RIS-Receiver Coordination: Passive Beamforming and Active Jamming

In this correspondence, we investigate the physical layer security issue with the assistance of a reconfigurable intelligent surface (RIS). In particular, we consider the single-input and multiple-output transmissions in the presence of a multi-antenna eavesdropper, where the legitimate receiver actively performs full-duplex jamming to confuse the eavesdropper. Meanwhile, the passive beamforming of the RIS is coordinated with the legitimate reception and jamming for security enhancement, leading to the joint optimization of receive beamforming, active jamming, and passive beamforming. The problem is solved under a block coordinate descent framework, where the receive beamforming is obtained through generalized eigenvalue decomposition, and the active jamming and passive beamforming are solved based on semidefinite programming. Simulation results show the combined effect of jamming and reflection upon the secrecy rate, also demonstrated is the performance superiority of the proposed scheme as compared with the conventional approaches in terms of wireless security.

Blocking jamming effect prediction method under multi-frequency in-band radiation environment for spectrum-dependent equipment

Blocking jamming effect prediction method under multi-frequency in-band radiation environment for spectrum-dependent equipment

Research on effective jamming style of projectile-carried communication for FH communication radio under common modulation systems

This work addresses the effective jamming style of projectile-carried communication for frequency hopping radio with different modulation by applying simulation verification via OPNET platform to construct the projectile-carried communication jamming system model. A general projectile-carried communication jamming style based on the signal combination of sweep saw-tooth wave and noise frequency modulation is proposed and analyzed. The network model of projectile-carried communication jamming system is constructed, and then the model building process of frequency hopping radio from the two aspects of transmitter model and receiver model is deeply elaborated. We demonstrate that the general projectile-carried communication jamming style has good jamming effect on the frequency hopping radio receivers with five modulation modes of 2FSK, 2PSK, 2DPSK, MSK and GMSK by comparing the simulation results, including receiving throughput, end-to-end delay, time delay of wireless channel access, delivery rate of synchronized header message, signal-to-noise ratio, bit error rate, packet loss rate, remaining power of jammer. Among them, the bit error rate of radio receiver with five modulation modes is more than 20%.

Radar Jamming Effect Analysis Based on Bayesian Inference Network With Adaptive Clustering

Radar jamming effect analysis (RJEA) is important for improving the performance of radar sensors in jamming environments and one of the most popular methods for RJEA is Bayesian inference network (BIN). Notice the features in RJEA are usually continuous, so they should be discretized for BIN, where the feature discretization approach determines the node sizes and the discretization error, which further seriously affect the training time and inference precision of BIN, respectively. In this paper, we put forward a adaptive clustering approach for the features in RJEA to reduce the node sizes of BIN in the premise of keeping or even improving its inference precision. To do so, a modified K-means algorithm is designed, where the initial clustering centers are preset according to the density of samples, and the number of final clustering centers, not given in advance, is estimated with their locations simultaneously via iterative optimization. Finally, the performance of BIN with the adaptive clustering is validated in the experiments on pulse Doppler radar sensor with radial frequency noise, where 20 features are extracted for RJEA. Compared with uniform discretization, the proposed method can reduce the training time of BIN from 19.52 second to 4.39 second and improve its inference precision from 71 % to 82% simultaneously. Compared with K-means discretization, the proposed method results in similar inference precision but less training time of BIN.

An efficient interference mitigation approach for NavIC receivers using improved variational mode decomposition and wavelet packet decomposition

AbstractReliable positioning, timing, and navigation services have become vitally important in safety and security applications. Hence, the need for Global Navigation Satellite Systems (GNSS) is growing continually. However, Continuous Wave Interference (CWI) was found to be one of the major potential threats of GNSS systems which degrades the receiver's performance. So, in this paper, a new approach using Improved Variational Mode Decomposition and Wavelet Packet Decomposition (IVMD‐WPD) has been proposed to mitigate CWI in NAVigation with Indian Constellation (NavIC) receivers. Although VMD is considered as an excellent signal analysis tool in decomposing non‐stationary and complex signals, the accuracy of the decomposition results depends upon the parameter setting. To address this, firstly, Normalized Kurtosis Energy Ratio (nKER) evaluation index is constructed. Then, the principle of nKER maximum is implemented to find the optimal parameters of VMD. Using the optimized parameters, the received signal is decomposed by IVMD into sub‐signals. Secondly, the mutual information index is introduced to extract the information dominant modes. The extracted modes are then processed by wavelet packet filter and finally, the desired signal is reconstructed. The proposed IVMD‐WPD method not only reduces the jamming efficiently but also overcomes the limitations of VMD. Moreover, by integrating IVMD with wavelet packet filter, the remaining effects of jamming and noise present in desired modes can be filtered thereby enhancing the performance. Simulation results reveal that the proposed method performs better in comparison with the conventional techniques in case of a single tone, multi‐tone, and chirp jamming environments.

Microbiologically-Synthesized Nanoparticles and Their Role in Silencing the Biofilm Signaling Cascade.

The emergence of bacterial resistance to antibiotics has led to the search for alternate antimicrobial treatment strategies. Engineered nanoparticles (NPs) for efficient penetration into a living system have become more common in the world of health and hygiene. The use of microbial enzymes/proteins as a potential reducing agent for synthesizing NPs has increased rapidly in comparison to physical and chemical methods. It is a fast, environmentally safe, and cost-effective approach. Among the biogenic sources, fungi and bacteria are preferred not only for their ability to produce a higher titer of reductase enzyme to convert the ionic forms into their nano forms, but also for their convenience in cultivating and regulating the size and morphology of the synthesized NPs, which can effectively reduce the cost for large-scale manufacturing. Effective penetration through exopolysaccharides of a biofilm matrix enables the NPs to inhibit the bacterial growth. Biofilm is the consortia of sessile groups of microbial cells that are able to adhere to biotic and abiotic surfaces with the help extracellular polymeric substances and glycocalyx. These biofilms cause various chronic diseases and lead to biofouling on medical devices and implants. The NPs penetrate the biofilm and affect the quorum-sensing gene cascades and thereby hamper the cell-to-cell communication mechanism, which inhibits biofilm synthesis. This review focuses on the microbial nano-techniques that were used to produce various metallic and non-metallic nanoparticles and their “signal jamming effects” to inhibit biofilm formation. Detailed analysis and discussion is given to their interactions with various types of signal molecules and the genes responsible for the development of biofilm.

Performance of optical space shift keying under jamming.

In this paper, the effect of jamming in a free-space optical (FSO) communication system that employs optical space shift keying (OSSK) is studied. The optical link suffers from saturated atmospheric turbulence (AT). Hence, the channel fading coefficients follow negative exponential probability density function (PDF). Along with additive Gaussian noise, the jammer, under consideration, is an additional source of noise, and jamming signals also suffer from saturated AT. Thus, the jamming channel also follows the negative exponential PDF. A multiple-input single-output (MISO) FSO system is used to mitigate the effects of jammer and channel fading. Explicitly, we employ a 2×1 MISO-OSSK system for analysis and derive a closed-form expression of bit error rate (BER) of the considered system. Moreover, the jammer's effect is also studied numerically under the gamma-gamma (GG) fading channel.

Reinforcement learning based a non-zero-sum game for secure transmission against smart jamming

Smart jammer and smart anti-jammer have always been attacked and defensed in a contradictory way. In fact, there exists fundamental trade-off between all evolved parties. It is well known that only through interactive training with powerful opponents can the strategy optimization ability in actual combat be improved. In the process of electronic countermeasures between the communication system and the jammer, the traditional electronic warfare attacker uses an open-loop jamming method, that is, the opponent's information cannot be obtained after the jamming, which greatly reduces the combat effect. In order to improve the strategic optimization capabilities of the combatant, cognition and intelligence are introduced into electronic countermeasures. In this paper, we start from modeling a non-zero-sum game, and analyze the Nash equilibrium (NE) of the static secure game and the conditions for its existence. Then, we design a multi-agent reinforcement learning framework with a optimal power control strategy in the dynamic game between the smart jammer and the trained base station (BS). Finally, due to the non-cooperative hostile relationship between the two sides in the actual combat, we add the eavesdropping function and the jamming effect evaluation modular to build a cognitive closed-loop. The experiment shows that the intelligent jammer with the eavesdropping function can seriously reduce the performance of the interfered communication party. However, the intelligent BS after training can effectively combat smart jamming. It can be demonstrated that confrontation training can improve the intelligence level of agents.

Intelligent Secure Networking in In-band Full-duplex Dynamic Access Networks: Spectrum Management and Routing Protocol

Recent developments in self-interference cancellation (SIC) techniques have made in-band full-duplex (IBFD) transmission systems possible. IBFD technology can enhance, or theoretically speaking double, spectrum utilization by allowing simultaneous transmission and reception using the same radio-frequency channel. Integrating the IBFD technology in cognitive radio (CR) systems can further enhance spectrum utilization and provide huge spectrum opportunities for efficient deployment of next-generation multi-hop wireless systems. Routing protocols for typical CR networks (CRNs) assume that CR users are equipped with half-duplex receivers. Limited number of protocols have been designed for FD-based CRNs. However, these protocols do not account for security threats in wireless environment, which could significantly affect system performance. In this paper, we develop a security-aware intelligent routing scheme that aims at mitigating the effects of jamming attacks on IBFD CRNs. This scheme considers the unique characteristics of the CRN environment while being IBFD-aware. Specifically, it considers the primary user’s channel-availability time, channel quality and jamming strategy. For a source-destination pair, our protocol collects a set of loop-free paths. Then, it attempts to assign channels for the hops along each path with the goal of achieving the highest Probability of Success (PoS) of each path. The per-hop channel selection for each path is derived as an optimization problem, for which sub-optimal solutions are found using a polynomial-time approximate method. Based on the computed channel assignment and PoS over each path, the path with the highest PoS between the source and destination is selected. Simulation results show that our secure-aware IBFD-based routing can significantly mitigate the jamming effects on CRN performance by improving the packet-delivery ratio, and consequently network throughput compared with existing FD-based routing protocols.

Hybrid anti‐jamming algorithm for Indian Regional Navigation Satellite System receivers using variational mode decomposition and wavelet packet transform

SummaryContinuous wave interference has found to be one of the major menaces that deter the performance of the Indian Regional Navigation Satellite System (IRNSS) receivers for seamless positioning and navigation. In this paper, a novel hybrid jamming mitigation method based on variational mode decomposition (VMD) and wavelet packet transform (WPT) has been proposed. VMD is used to decompose the received signal into various components referred to as intrinsic mode functions (IMFs). To have an optimum decomposition of the signal, the mode decomposition number of VMD is determined by employing the kurtosis principle. Then, a threshold based on the mutual information index is constructed to differentiate the information dominant and interference dominant modes. The information dominant modes are then processed by the wavelet packet filter to eliminate the remaining effects of jamming and noise present. Finally, the filtered modes and the retained modes are used to reconstruct the desired signal. The performance of the technique is analyzed in the presence of single‐tone, multitone, and chirp jamming scenarios with different levels of jamming power. The proposed method has been tested by simulations in comparison with the standard algorithms. Results show that the proposed hybrid algorithm outperforms the standard algorithms in reducing the jamming signal effectively.

Time-Domain Scattering Characteristics and Jamming Effectiveness in Corner Reflectors

The outboard corner reflectors are widely used as a countermeasure to radar tracking and detection. Therefore, it is essential to determine the composite time-domain scattering characteristics of the corner reflector and ship against the sea background and the jamming effectiveness of the corner reflector array. In this paper, the composite electromagnetic scattering characteristics of ship target, corner reflector, and the sea surface are studied based on the time-domain bouncing ray method (TDSBR). The radar echo and broadband radar cross section (RCS) results for the time domain pulse incident are also obtained and the high-resolution range profile (HRRP) is calculated. We then devise an evaluation system based on centroid jamming intensity and range profile similarity to determine the jamming characteristics of passive jamming. We further propose an array composing of three sizes of corner reflectors. Finally, the centroid jamming effectiveness is analyzed by comparing the RCS of the corner reflector array and the ship, and the deception jamming effectiveness is measured by calculating the range profile similarity based on the cosine similarity method and the range profile peak envelope overlap. Simulation results show that the reflector array can achieve a good performance both for centroid and range profile deception. The simulation results given and the evaluation method proposed in this paper provides significant practical insights into the design and analysis of the passive jamming systems.

An evolutionary band-limited Gaussian noise jamming algorithm for LMS-based GPS

In this paper, evolutionary algorithm is used to optimize the flicker function of band-limited Gaussian noise interference, which disturbs the convergence of adaptive algorithm based on LMS in GPS receiver, so that the average null depth of GPS receiver under equal power is lower, and better jamming effect is achieved. The simulation results show that the jamming algorithm in this paper has better jamming effect than the band-limited Gaussian noise jamming in different jamming quantity.

Evaluation of Deceptive Jamming Effect on SAR Based on Visual Consistency

In complicated electromagnetic environments, synthetic aperture radar (SAR) can be threatened by various kinds of malicious interference, of which deceptive jamming is the intentional and efficient one. For jamming effect evaluation on SAR images, traditional methods are mostly based on the change of image quality, while not suitable for evaluating the confusion caused by high-fidelity false targets. In this paper, a novel framework to evaluate the effect of deceptive jamming on SAR is proposed based on visual consistency (VC). Three levels of vision, namely detection, recognition and semantics, are fused for efficient deception evaluation along with the corresponding metrics system. Fully considering the imaging characters of deceptive jamming, specifically designed detection and recognition flows are introduced to quantitatively evaluate the deception. Furthermore, to evaluate whether the generated false targets are with reasonable context, a unprecedent concept named semantic accuracy is proposed via considerations of statistical differences compared with that of the background template. Besides, the cases that deceptive jamming with several common non-ideal issues are considered when evaluating the effects. Sufficient experiments have proved the practicality and superiority of the proposed evaluation framework under different deceptive jamming with various non-ideal factors.

A New Efficient Two-Sided Complementary Code Based Channel Estimation Technique “TSCC-CE” for MIMO-OFDM Systems, Under the Effects of Partial-Band Jamming and Doppler Spread

Channel estimation (CE) is a field of study that has garnered much attention during recent years. CE plays an important role in developing channel equalizers. There are many approaches to CE, among which there are orthogonal codes (OC) and orthogonal space-time block codes (OSTBC). Also, complementary codes (CC) have been under investigation for multiple-input, multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) CE. There are zero side-lobe levels in a CC signal’s autocorrelation function. The initial area of application of these signals has been radar systems, and they were used as optimal phase-coding signals. These signals require the use of two different channels to transmit the twofold components of the pilot code. Thus, this research introduces the two-sided CE (TSCE), where separate subcarrier locations are used to carry the two pilot CCs. Equalization errors can occur in dangerous situations, in case a system is interfered with or jammed. This leads to negative impacts on the accuracy of channel estimation. This situation specifically occurs when a harsh Doppler spread is present, as a result of a deterioration in the orthogonality of the subcarriers of the OFDM. Certain conditions were applied for testing the performance of the method suggested in this paper, i.e., the MIMO-OFDM TSCE approach, the method that depends on CCs. These conditions are the Doppler spread, as well as partial-band jamming. Among the different MIMO-OFDM CE techniques, TSCC-CE has shown good performance, with its ability to withstand the effect of partial-band jamming on the accuracy of the MIMO-OFDM CE. This improved performance takes place in the presence of a Doppler spread of moderate value and a partial-band jamming ratio.

User cooperation to mitigate the jamming in OFDMA networks

In this paper, jamming and anti-jamming in a time slotted orthogonal frequency division multiple access (OFDMA) are investigated. The users of the network cooperate to mitigate the jamming effect. Interactions among the network users and the jammer are modeled by a mixed integer non-cooperative generalized game which is a NP-hard problem. To relax the problem, a new algorithm is proposed based on channel state information (CSI) to determine the transmission channels and the partners of users in the network. To solve the proposed game, an optimization problem is solved for each player considering the best response of the other player. Another generalized game is proposed to model the cooperation among users of the network. The latter game is transformed to an equivalent Quasi Variational Inequality (QVI). Then, a new gradient based algorithm is proposed by utilizing the Karush-Kuhn-Tucker (KKT) conditions to find the solution of the equivalent QVI. Then, solving the latter game and substituting the best related response, the solution of the former generalized game is also obtained. The convergence of the proposed algorithms, and the uniqueness related to the solution of the both generalized games are proven. Finally, the simulation results confirm the effectiveness of the proposed approach.

Evaluation method of laser jamming effect based on deep learning

Evaluation method of laser jamming effect based on deep learning