Transmission Capacity Research Articles

100Gb/s coherent optical secure communication over 1000 km based on analog-digital hybrid chaos.

In recent years, the transmission capacity of chaotic secure communications has been greatly expanded by combining coherent detection and multi-dimensional multiplexing. However, demonstrations over 1000 km fiber are yet to be further explored. In this paper, we propose a coherent optical secure transmission system based on analog-digital hybrid chaos. By introducing an analog-digital converter (ADC) and a bit extraction into the feedback loop of entropy source, the broadband analog chaos is converted into a binary digital signal. This binary digital signal is then mapped to a 65536-level pulse amplitude modulation (PAM) signal and injected into the semiconductor laser (SL) to regenerate the analog chaos, forming a closed loop. The binary digital signal from the chaos source and the encrypted signal are transmitted via wavelength division multiplexing (WDM). By using conventional digital signal processing (DSP) algorithms and neural networks for post-compensation, long-haul high-quality chaotic synchronization and high-performance secure communication are achieved. In addition, the probability density distribution of the analog chaotic signal is effectively improved by adopting the additional higher-order mapping operation in the digital part of the chaos source. The proof-of-concept experimental results show that our proposed scheme can support the secure transmission of 100 Gb/s quadrature phase shift keying (QPSK) signals over 1000 km of standard single-mode fiber (SSMF). The decrypted bit error rate (BER) reaches 9.88 × 10-4, which is well below the 7% forward error correction (FEC) threshold (BER = 3.8 × 10-3). This research provides a potential solution for high-capacity long-haul chaotic optical communications and fills the gap in secure communications based on analog-digital hybrid chaos.

Seven levels highly efficient modular multilevel matrix converter (M3C) for low frequency three-phase AC-AC conversion

An Innovative Modular multilevel matrix converter (M3C) is proposed with reduced number of switching device owing to the improved efficiency, reduced cost and minimizes the size. Offshore Low-Frequency AC (LFAC) transmissions are economical with greater reliability for short and intermediate distance transmissions. Similar to HVDC, it increases the transmission capacity and also distance can be increased in LFAC.M3C is proposed as frequency converters for LFAC transmissions which link AC systems operating at 16.7 and 50 Hz. The double αβ0 transform control technique has been the most often used approach for decoupling control of input, output and circulating currents in such applications. The performances of this work’s proposed modular multilevel matrix converters are analysed using simulation in MATLAB/SIMULINK software.

Phylogenetic Investigations of Dengue 2019-2021 Outbreak in Guadeloupe and Martinique Caribbean Islands.

Dengue fever has been a public health problem in the Caribbean region since 1981, when it first reappeared in Cuba. In 1989, it was reported in Martinique and Guadeloupe (two French islands 200 km apart); since then, DENV has caused several epidemics locally. In 2019-2021, DENV-1, DENV-2, and DENV-3 were detected. Serotype distribution was differentiated, with DENV-2 and DENV-3 predominating in Guadeloupe and Martinique, respectively. Complete genome sequencing was carried out on 32 specimens, and phylogenic analysis identified the circulation of genotype V for DENV-1, cosmopolitan genotype for DENV-2, and genotype III for DENV-3. However, two distinct circulating groups were identified for DENV-1 and DENV-3, suggesting independent introductions. Overall, despite the context of the COVID-19 pandemic and the associated travel restrictions, these results confirm the active circulation of DENV and specific epidemiological features on each of the two islands. Such differences may be linked to the founder effect of the various introduction events, and to local factors such as the population immunity and the transmission capacity of the vectors. Further genomic and epidemiological characterization of DENV strains remains essential to understand how dengue spreads in each specific geographical context and to prevent future epidemics.

Battling the extreme: lessons learned from weather-induced disasters on electricity distribution networks and climate change adaptation strategies

Abstract Electricity infrastructures are critical lifeline systems that are designed to serve with a high degree of reliability the power supply of consumers under normal operating conditions and in case of common failures or expected disturbances. However, many recent weather-induced disasters have brought unprecedented challenges to the electricity networks, underlining that power systems remain unprepared to absorb disruptive large-scale and severe events. Worse still, it is expected that such climate hazards will take place at rising frequency and intensity rates due to climate change. The intensification of meteorological extremes will lead to higher losses and changes in transmission capacity, increasing the frequency and importance of material damage to the aging electric infrastructure, thus resulting in significant disruptions, cascading failures, and unpredictable power outages. This review paper presents real-life examples of different types of extreme weather incidents and their impacts on the distribution network in Greece, a country that is highly vulnerable because of its location, geomorphology, and the existing overhead network assets, highlighting lessons learned related to adaptation options and disaster management best practices. Literature review and benchmarking with other grid operators are also employed to explore resilience-enhancing technical capabilities, weatherproof solutions, and operational strategies on which policy-making initiatives should focus.

Future trends in optical wireless communications systems: Review

Optical fibers are frequently used in data transmission systems, Because of their ability to transmit large amounts of information and dielectric nature. In central, metropolitan, or broad-area applications, network topologies incorporating many wavelengths per optical fiber are utilized to connect thousands of users with a wide variety of transmission rates and capacities. The simultaneous transmission of many wavelengths over a fiber with a nm range of 1300 to 1600 is a potent characteristic of an Optical communication network. Wavelength division multiplexing (WDM) is a method for combining various wavelengths onto a single fiber. The WDM concept, when combined with optical amplifiers, produces communication lines that enable quick communication between users across national borders. An overview of the difficulties with fiber-optic communication is provided in this paper. The areas that will be most important for the development of optical communications in the future are outlined in this study. Modern optical fibers and integrated optics were both developed in the dominion of optical machinery and parts. Optical fiber communication systems are widely used for high-speed data transmission over long distances. There are some specific details and examples of optical fiber communication systems such as Fiber Optic Cables, Light Sources, optical modulator, optical amplifier, optical receivers, fiber optical network, medical applications.

Low-Complexity Conditional Generative Adversarial Network (c-GAN) Based Nonlinear Equalizer for Coherent Data-Center Interconnections

Nonlinear impairments emerging from both fiber optical links and optoelectrical devices are the major bottleneck for enhancing the throughput of photonic data-center interconnection (DCI). Here, we propose a data-driven nonlinear equalizer based on a conditional generative adversarial network (c-GAN) for high-speed and large-capacity photonic DCI. Its performance is experimentally evaluated by transmitting C-band 40-channel 60-GBaud dual polarization-16 quadrature amplitude modulation (DP-16QAM) dense wavelength division multiplexing (DWDM) signals over 20-km standard single-mode fiber (SSMF). Our experimental results verify that, the proposed c-GAN equalizer outperforms both traditional nonlinear equalizers and other data-driven counterparts, in terms of both the bit-error ratio (BER) and computational complexity. Only the proposed c-GAN equalizer can guarantee the BER performance of all 40 channels to reach the threshold of 20% soft decision forward error correction (SD-FEC) at BER=0.027, leading to a net transmission capacity of 16 Tb/s. Meanwhile, the computational complexity of the proposed c-GAN equalizer can be significantly reduced by 31.8%, 80.7%, and 98.8%, respectively, in comparison with Volterra filter equalizer (VFE), multilayer perceptron (MLP), and long short-term memory neural network (LSTM-NN) schemes.

Decoupling Methods in Planar Ultra-Wideband Multiple-Input-Multiple-Output Antennas: A Review of the Design, State-of-the-Art, and Research Challenges

Ultra-wideband (UWB) antennas cover a frequency range of 3.1 to 10.6 GHz and have sparked a lot of research interest as an essential part of wireless communication systems as they provide high data transmission speeds, are less expensive, and consume less power. UWB antennas are widely used in radar imaging, radio frequency identification, public security, and other high-accuracy positioning devices such as altimetry. Some smart applications of UWB antennas are vehicular radar systems, surveillance systems, software-defined radios, spectrum analysis, proximity fuses, etc. Multiple-input-multiple-output (MIMO) is a multiplexing technology that adopts multiple antennas both at the transmitter and receiver, which can enhance the channel capacity. MIMO technology is extensively used in several applications, such as in portable devices, wireless body area networks (WBANs), vehicular communication, and satellite–terrestrial networks. Generally, the MIMO antennas are used to obtain high reliability, high capacity, high throughput, and high security. The UWB MIMO antennas (UMAs) are considered the best choice for wireless communication systems as they offer reliability and wide transmission capacity, in contrast to unit antenna elements (AEs), without increasing system bandwidth or transmission power. The present-day and future communications systems need higher throughput to meet the demands of users. The signal transfer rate can be improved by improving channel bandwidth or increasing the number of receiving antennas. However, the main issue in designing UMAs is to provide high isolation between AEs because mutual coupling interactions between them affect the generated radiation patterns, leading to worse performance and failing to meet the operative constraints and requirements. When introducing decoupling techniques (DTs), researchers experience numerous challenges, including an increase in antenna size, design complexity, and cross-polarization. This article offers an organized review and simulated study of the various DTs in UMAs. The simulated study has been carried out through the implementation of various types of DTs on the same two-port UMA, which consists of two microstrip-fed circular-shaped AEs with open-end slotted partial ground. In contrast with previously reported review articles, this article provides a detailed study of various types of DTs reported so far and a better understanding for selecting appropriate DTs, which help in designing UMAs with better performance.

Natural gas as a transition bridge by 2035 and its transmission capacities adequacy

ABSTRACT This paper analyzes the potential for natural gas in Austria, the Czech Republic, and Slovakia in order to develop a model that accurately describes the adequacy of transmission capacities in the region up until the year 2035. Two scenarios are created using the model. The first scenario is based on the situation prior to the Russian-Ukrainian conflict, while the second scenario considers the conflict, allowing to observe its impact. In the Original Scenario, gas was an indisputable part of the energy mix, and it was desirable to increase the transmission capacity. In contrast, the Reduction Scenario aims to reduce gas consumption and to diversify the portfolio of suppliers, which makes its role uncertain. Under this scenario the flow distribution significantly changes and neglects the transit role of the selected region. The surprising result was that the flow through Ukraine became the main gas flowing from Russia. Both scenarios also shared a common outcome – the importance of storage capacities.

Towards an optical MIMO system performance improvement using MGDM multiplexing and EDFA optical amplification

This paper proposes a creative (3 × 3) MIMO transmission system employing multimode fibers MMF and MGDM spatial multiplexing technology. Based on spatial injection and spatial detection of light beams, the MGDM approach allows the MMF fiber to benefit from its entire bandwidth and increase its transmission capacity. To increase the quality and transmission capacity, the injection and detection parameters have been optimized. The transmission and reception conditions on the optical fiber are adjusted to ensure the transfer of high-speed services. Thus, ideal injection and detection conditions increase the quality of signals received on an MMF fiber. The proposed transmission chain decreases the modal and chromatic dispersions during transmission, for this reason, three subsystems interconnected by spatial connectors are created. To decrease interference between the modes of the same groups and to correct for attenuation of the signal on a 1200 m cable, two EDFA optical amplifiers were integrated. The simulation of the proposed chain (3 × 3) MIMO of distance 1.2 Km is realized to transmit data with a total rate of about 4.5 Gb/s (1.5 Gb/s for each user). Then, the comparison between the BER and quality factor Q performance was done for a system with and without optical amplifier.

Integration of wave energy into Energy Systems: an insight to the system dynamics and ways forward

Wave energy is a rich and highly accessible renewable energy resource, that has largely been under-developed. Studies from the sector have tried to show the potential of benefits wave energy in “simple cases” or via small hybrid systems, the large scale incorporation of wave energy has not yet been fully investigated. Our approach uses a fully dynamic climate driven energy system model, which has undergone modifications to include wave energy converters and their associated dependencies.
 This study explores the system dynamics and important elements that will be used for large scale wave energy integration; in a fully coupled European Energy System. We explore the cost pathways of different wave energy converters, the impact of climate data, and the impact of transmission capacity expansion under cost-optimal configurations of a multi-renewable European power system. From this preliminary approach we aim to provide the boundary conditions, and assumptions that will govern the integration of wave energy into the European Energy System up to 2050.

Research on identification method of power equipment hot spot temperature based on the particle filter algorithm

With the construction of new power systems, the load shows significant differences between peak and valley, and the traditional system planning and scheduling operation mode faces problems such as insufficient flexibility. The power system mainly focuses on transmission lines and transformers to improve the grid’s transmission capacity. Based on the existing grid structure and substation layout, the thermal stability value algorithm is used to evaluate the load capacity of substation equipment, fully tap its operation potential, and improve the equipment’s total utilization rate, which is of great significance to ensure the reliability of the power supply. Based on the principle of heat transfer, this paper establishes the temperature model of electrical equipment contact. Finally, the experimental results demonstrate that the particle filter method proposed in this paper can effectively predict the model temperature.

Genetic and structural analyses reveal the low potential of the SARS-CoV-2 EG.5 variant.

The severe acute respiratory syndrome coronavirus 2 EG.5 lineage is the latest variant under monitoring, and it is generating significant concern due to its recent upward trend in prevalence. Our aim was to gain insights into this emerging lineage and offer insights into its actual level of threat. Both genetic and structural data indicate that this novel variant presently lacks substantial evidence of having a high capacity for widespread transmission. Their viral population sizes expanded following a very mild curve and peaked several months after the earliest detected sample. Currently, neither the viral population size of EG.5 nor that of its first descendant is increasing. The genetic variability appear to be flattened, as evidenced by its relatively modest evolutionary rate (9.05 × 10-4 subs/site/year). As has been observed with numerous prior variants, attributes that might theoretically provide advantages seem to stem from genetic drift, enabling the virus to continually adjust to its host, albeit without a clear association with enhanced dangerousness. These findings further underscore the necessity for ongoing genome-based monitoring, ensuring preparedness and a well-documented understanding of the unfolding situation.

Research on Step-down Resonance Suppression and Filtering Device

In recent years, offshore wind farms have developed rapidly, and their installed capacity is getting bigger and bigger, and the offshore distance is getting farther and farther. In order to meet the needs of large-capacity and long-distance offshore wind power transmission, the AC submarine cable has the characteristics of long distance, high voltage and large cross-section. Along with the significantly improved transmission capacity, its equivalent capacitance is also increasing, which further reduces the resonance frequency of the offshore wind power AC transmission system. If the parallel resonance frequency of the offshore wind power transmission system is close to the main harmonic current frequency band of wind turbines, it will cause harmful system resonance and harmonic amplification, significantly increasing the harmonic current of grid-connected lines and the voltage distortion rate of nodes in nearby power grids, and seriously affect the safety of equipment and the safe and stable operation of offshore wind power transmission system. A step-down resonance suppression filtering device applied to the offshore wind power transmission system is proposed. The AC cable is connected to the low-voltage 35 kV side of the compensation winding of the centralized control center to eliminate the resonance risk of the 220 kV system and filter out the harmonic current. Compared with the existing technical scheme, the device has the advantages of simple control, reliable operation, stable resonance suppression effect, low operation loss and the like, and has great engineering popularization value.

Impact of the band upgrade sequence on the capacity and capital expenditure of multi-band optical networks

Multi-band transmission over existing fibers would be a key strategy for ongoing capacity expansion even though upgrading from the conventional C band to multi-band, such as the C+L-band transmission being deployed by operators, would be a slow and complex process. After the C+L band, which band should be upgraded first in the next stage is an open question. We try to answer this by proposing three different band upgrade strategies, including near-to-far, far-to-near, and performance-prediction strategies, and comparing the potential capacity increase and the investment cost to upgrade different bands. We introduce an optical signal-to-noise ratio (OSNR) estimation model comprehensively covering various impairments to evaluate the quality of transmission of an optical channel and develop what we believe to be a novel method to find optimal launch powers for optical channels. Along with routing and spectrum assignment, an OSNR-aware traffic grooming algorithm is also developed to evaluate the capacity that can be achieved after upgrading different bands in an optical network. Our study shows that the performance-prediction strategy always outperforms the other two strategies. When capacity is considered a key performance metric, the E band should be the first to be upgraded next since it both expands the transmission capacity significantly using only a few additional amplifiers and the band upgrade sequence should be E, O, S, and U. For the performance-prediction strategy, we also evaluate the impact of the upgraded band on the performance of other bands. It is found that the upgraded band always has a significant impact on adjacent bands, with the upgrade of high-frequency bands improving the performance of existing low-frequency bands and the upgrade of low-frequency bands degrading the performance of existing high-frequency bands. In addition, the “C+L+E+O+S+U” scenario can achieve 3 times the capacity of the “C+L” scenario when all the bands are upgraded.

An Optimized Node Level Lightweight Security Algorithm for Cloud Assisted-IoT

The fastest-evolving technology, the Internet of Things (IoT), will advance the fields of agriculture, defense, and medical electronics. IoT is focused on giving every object a purpose. IoT with cloud assistance offers a potential remedy for the issue of data expansion for individual objects with restricted capabilities. With the increasing use of cloud technology, the Internet of Things (IoT) has encountered additional security hurdles when it comes to exchanging data between two parties. To address this issue, a thorough investigation was conducted into a secure cloud-assisted strategy for managing IoT data, which ensures the safety of data during its collection, storage, and retrieval via the cloud, while also considering the growing number of users. To achieve this, a lightweight security mechanism that is optimized at the node level is implemented in the proposed system. By utilizing our technology, a secure IoT infrastructure can be established to prevent the majority of data confidentiality threats posed by both insiders and outsiders. Using a heartbeat sensor and a node MCU, we create a heartbeat monitoring system. At the node MCU level, giving security to the patient's health data and preventing unauthorized users from attacking it. Smaller key sizes and lightweight security techniques for IoT devices with minimal power, lower power and memory consumption and Execution time, transmission capacity reserve is used to achieve security. In order to achieve this. The performance of the RSA and ECC algorithms in terms of execution time, power consumption, and memory use have been tabulated for this experimental arrangement. The ECC method occurs to produce the best results in tiny devices.

Calculation and optimization of inter-regional available transfer capability considering wind power uncertainty and system improvement measures

The intermittency and uncertainty of wind energy make transmission congestion management increasingly complex. In this paper, we investigate the impact of wind energy on available transmission capacity (ATC) and then explore ways to mitigate transmission congestion from the grid and load side, respectively. The impact of a stochastic variable is considered by applying Latin Hypercube Sampling (LHS) and backward curtailment techniques to generate typical scenarios. ATC is improved by the optimal allocation of Thyristor Controlled Series Compensation (TCSC) on the grid side and the use of Demand Response (DR) on the load side. The source-grid-load cooperative optimisation model for ATC is solved by an improved particle swarm optimisation (PSO) algorithm. Based on the IEEE-30 bus system, an experimental scheme is designed and analytical calculations are performed. The results show that the joint application of TCSC and DR can help to improve ATC in a comprehensive way. The work done in this paper can achieve the purpose of promoting renewable energy consumption by improving the utilisation efficiency of the transmission network without changing the network structure.

The luminous transmittance of the quartz-glass fiber posts is superior to glass fiber posts.

To evaluate the light transmission capacity of two types of fiber posts, using two different methods. The posts were divided into two groups: experimental group - quartz-glass fiber posts (n=10) and control group - glass fiber posts (n=10). The light transmittance of the samples was compared by means of light intensity test by photographs and ultraviolet-visible spectrophotometer. This test was analyzed by thirds: coronal, middle, and apical. The spectophotometer tested the luminous transmittance along the length of the post. The statistical analysis was conducted with a significance level of 0.05. Light transmission was 97% on the coronal third, 68% in the middle third, and 27.66% in the apical third in the posts of the experimental group. In the posts of the control group, the light transmission was 95.33% in the coronal third, 80.66% in the middle third, and 41.33% in the apical third. Light transmission was significantly higher in the middle third of the posts of the experimental group when compared to the control group (p<0.05). The luminous transmittance of the posts of the experimental group was 97.4% with wavelengths of 400 nm, 97% at 450 and 500 nm, and 96.9% at 550 nm. In the posts of the control group, the luminous transmittance was 72.3% with wavelengths of 400 nm, 68.6% at 450 nm; 64.6% at 500 nm and 61.5% at 550 nm. The posts of the experimental group demonstrated significantly higher light transmittance than the control group (p<0.001).

A New Method for Evaluating Natural Gas Pipelines Based on ICEEMDAN-LMS: A View of Noise Reduction in Defective Pipelines

As the main means of energy transportation, pipelines have the characteristics of 24 h uninterrupted transportation, low cost, strong transmission capacity, and low risk, and they have become an important device for natural gas transportation. However, due to defects caused by the pipeline itself and external forces, it is easy for natural gas leakage to cause major accidents, serious environmental pollution, and huge losses of life and property. Traditional pipeline defect detection technology can be interfered with by a large number of noise signals when collecting defect signals, and the noise reduction method is simple but has poor accuracy, so it cannot directly obtain effective pipeline defect information from the signal and cannot effectively improve the emergency intensity and emergency level of pipeline operation and maintenance management. Therefore, a new noise reduction method, ICEEMDAN-LMS, for natural gas pipelines is proposed in this paper, and the method is calculated and tested in detail. The effectiveness of the new method is verified through the analysis of a pipeline defect signal and normal signal. Moreover, the proposed method can reduce noise more effectively than conventional methods, which has clear value in engineering applications. Importantly, this noise reduction method not only provides a reliable basis for the intelligent diagnosis of pipeline defect signals, but can also be an important reference for helping management departments to make decisions and emergency plans and formulate on-site treatment programs.

Enhancing security and capacity in FSO transmission for next-generation networks using OFDM/OCDMA-based ICSM codes

In order to address the growing demands for both enhanced security levels and increased transmission capacity, this research proposes a novel approach for free space optical (FSO) transmission. The proposed design incorporates an identity column shift matrix (ICSM) code to ensure robust security. Additionally, capacity enhancement is achieved through the utilization of a 4-level quadrature amplitude modulation (4-QAM) scheme in conjunction with an orthogonal frequency division multiplexing (OFDM) modulator. The performance of the system is evaluated across three channels, each transmitting data at a rate of 20 Gb/s, while operating in an FSO channel that is subjected to varying atmospheric attenuation effects and atmospheric turbulence. Real meteorological data from three different cities [Alexandria, Egypt; Jeddah, Kingdom of Saudi Arabia (KSA); and Hyderabad, India], situated across two continents, are incorporated to demonstrate the practicality of implementing the proposed model in real-world environments. The experimental results reveal that an increase in atmospheric turbulence leads to a higher bit error rate (BER) and lower received optical power (ROP), resulting in degraded data reception. Furthermore, the study examines the impact of weather conditions, indicating that the longest and shortest propagation ranges of 12.5 and 0.286 km, respectively, are achieved under clear weather and heavy dust storms. These conditions yield an ROP of −9.5 dBm and a log (BER) of approximately −2.5. Conversely, in the presence of strong turbulence, the performance further deteriorates. The proposed model demonstrates its ability to transmit a message signal over a distance of 0.8375 km, with a log (BER) of −2.6 under weak atmospheric turbulence. However, under strong atmospheric turbulence at the same distance, the log (BER) increases to −0.5. Regarding specific cities, the FSO range for transmitting information signals is found to be 9.58 km in Jeddah, which decreases to 6.58 km in Alexandria and 5.17 km in Hyderabad due to the increased atmospheric attenuation in these cities.

Dynamic output-feedback model predictive control for polytopic uncertain systems with amplify-and-forward relays

In this paper, the dynamic output-feedback model predictive control (MPC) problem is investigated for systems with polytopic uncertainties and amplify-and-forward (AF) relays, where the signal transmission with random power is adopted to facilitate the remote transmission with the limited transmission capacity of sensors. With respect to the parameter uncertainties of the system and the randomness of AF relays, a new objective function is constructed, which is defined by the mathematical expectation of the conventional quadratic function over the infinite time horizon. Then, the singular value decomposition technique is applied to handle the inherent couplings of variables to formulate a solvable optimization problem. Furthermore, sufficient conditions are provided to guarantee the recursive feasibility of the proposed MPC algorithm, meanwhile the underlying system can be stabilized in the mean-square sense by the designed controllers. Finally, two simulation examples are used to show the effectiveness of the proposed MPC strategy.