Search Results (719)

In communication environments with limited computing resources, securely and efficiently transmitting image data has become a challenging problem. However, most existing image data protection schemes are based on high-dimensional chaotic systems as key generators, which suffer from issues such as high algorithmic complexity and large computational overhead. To address this, this paper presents new designs for a 1D Sine Fractional Chaotic Map (1D-SFCM) as a random sequence generator and provides mathematical proofs related to the boundedness and fixed points of this model. Furthermore, this paper improves the traditional 2D compressive sensing (2DCS) algorithm by using the newly designed 1D-SFCM map to generate a chaotic measurement matrix, which can effectively enhance the quality of image recovery and reconstruction. Moreover, referring to the principle of gene mutation in biogenetics, this paper designs an image encryption algorithm based on DNA base substitution. Finally, the security of the proposed encryption scheme and the quality of image compression and reconstruction are verified through indicators such as key space, information entropy, and Number of Pixel Change Rate (NPCR). Full article

The use of advanced switching technologies, including hybrid and fully semiconductor-based circuit breakers, enables a significant reduction in the prospective short-circuit current. This enhances the level of circuit protection by minimizing thermal and electrodynamic stresses. One of the available solutions is a hybrid DC circuit breaker employing the forced commutation method, in which a counter-current generator is incorporated into the auxiliary branch. Increasing requirements not only for short-circuit protection reliability but also for operational flexibility impose the need to configure DC breakers for parallel operation. This paper presents an analysis of the performance of forced-commutation circuit breakers connected in parallel with another identical device, as well as with a conventional fast magnetic blow-out breaker. To prevent unintended and undesired tripping, the influence of counter-current generator parameters on the overcurrent protection response was investigated. In the analyzed configuration, the applied hybrid DC breaker limits the expected short-circuit current from approximately 45 kA to 5 kA within about 2 ms. Full article

Recently, the installed generation capacity of wind energy has expanded significantly, and the doubly fed induction generator (DFIG) has gained a prominent position amongst wind generators owing to its superior performance. It is extremely vital to enhance the low-voltage ride-through (LVRT) capability for the wind turbine DFIG system because the DFIG is very sensitive to faults in the electrical grid. The major concept of LVRT is to keep the DFIG connected to the electrical grid in the case of an occurrence of grid voltage sags. The currents of rotor and DC-bus voltage rise during voltage dips, resulting in damage to the power electronic converters and the windings of the rotor. There are many protection approaches that deal with LVRT capability for the wind turbine DFIG system. A popular approach for DFIG protection is the crowbar technique. The resistance of the crowbar must be precisely chosen owing to its impact on both the currents of the rotor and DC-bus voltage, while also ensuring that the rotor speed does not exceed its maximum limit. Therefore, this paper aims to obtain the optimal values of crowbar resistance to minimize the crowbar energy losses and ensure stable DFIG operation during grid voltage dips. A recent optimization technique, the Starfish Optimization (SFO) algorithm, was used for cropping the optimal crowbar resistance for improving LVRT capability. To validate the accuracy of the results, the SFO results were compared to the well-known optimization algorithm, particle swarm optimizer (PSO). The performance of the wind turbine DFIG system was investigated by using Matlab/Simulink at a rated wind speed of 13 m/s. The results demonstrated that the increases in DC-link voltage and rotor speed were reduced by 42.5% and 45.8%, respectively. Full article

Dendritic cells (DCs) are among the first immune cells to detect viral invasion and play a central role in initiating and shaping antiviral immune responses. Many innate and adaptive immune functions of DCs are regulated by cathepsins, proteolytic enzymes primarily found in acidic endolysosomal compartments. Different DC subsets exhibit distinct cathepsin expression patterns, influencing their functional capacities and interactions with viruses. In DCs, cathepsins contribute to virus sensing through innate receptors, regulate cytokine production and DC migration, and are essential for viral antigen degradation and loading onto MHC molecules for T-cell activation. Many viruses, however, have evolved mechanisms to alter cathepsin expression and activity, thereby subverting DC function and promoting their own persistence. Indeed, cathepsins can facilitate viral entry into DCs, promote viral replication, and support immune evasion strategies. In this review, we summarize recent advances in understanding the role of cathepsins in DC–virus interactions, emphasizing both how DCs exploit cathepsins to generate protective immune responses and how viruses manipulate cathepsin activity to their advantage. We particularly focus on clinically relevant viral pathogens, including HIV, influenza virus, hepatitis C virus, human cytomegalovirus, Ebola virus, and SARS-CoV-2, to illustrate the multifaceted influence of cathepsins on DC biology during viral infection. Full article

This paper describes the modeling, simulation, and experimental validation of a Hybrid supercapacitor–battery Energy Storage System (HESS) for photovoltaic (PV) modules under partial shading. The system is intended to provide an uninterruptible power supply for a DC primary load. The Hybrid Power System (HPS) architecture includes a DC/DC boost converter with a Maximum Power Point Tracking (MPPT) algorithm that optimizes photovoltaic (PV) energy extraction. Furthermore, two bidirectional DC–DC converters are dedicated to the battery and supercapacitor subsystems to allow the bidirectional power flow within the HPS. The proposed HESS is evaluated through MATLAB/Simulink simulations and experimentally validated on a prototype using real-time hardware based on the dSPACE DS1104. To optimize power flow within the HPS, two energy management strategies are implemented: the Thermostat-Based Method (TBM) and the Filter-Based Method (FBM). The results indicate that the thermostat-based strategy provides better battery protection under shading conditions. Indeed, with this approach, the battery can remain in standby for 300 s under total permanent shading (100%), and for up to 30 min under dynamic partial shading, thereby reducing battery stress and extending its lifetime. Full article

Background: Toxoplasma gondii is a globally distributed apicomplexan parasite capable of causing congenital infections and spontaneous abortions in humans. While the parasite-secreted effector proteins TgGRA28 and TgGRA83 are known to mediate virulence or immune modulation, their potential as vaccine targets remains unexplored. Despite its immunomodulatory properties, the role of IL-28B (a type III interferon) in enhancing DNA vaccine efficacy against T. gondii infection remains unclear. Methods: In this study, we constructed eukaryotic expression plasmids pVAX-GRA28, pVAX- GRA83 and pVAX-IL-28B. After transfection into -293-T cell, protein expression encoding TgGRA28 and TgGRA83 was confirmed via indirect immunofluorescence assay (IFA), while IL-28B expression was analyzed by ELISA. Subsequently, C57BL/6J or IFNαR1 knockout mice were immunized with single or dual-antigen DNA vaccines, with or without the molecular adjuvant pVAX-IL-28B. Immune responses were assessed through Toxoplasma-specific antibody levels, cytotoxic T lymphocyte (CTL) activity, cytokine profiling (IFN-γ, IL-2, IL-12p40, IL-12p70), and flow cytometric analysis of lymphocyte subsets and dendritic cells (DCs). Protective efficacy was determined by survival rates and brain cyst burden following challenge with 100 or 10 ME49 T. gondii cysts, respectively. Results: Vaccination with pVAX-GRA28 and pVAX-GRA83 elicited robust humoral immune responses with increased T. gondii-specific IgG levels and also Th1-polarized immunity, characterized by elevated IgG2a/IgG1 ratio, IFN-γ-dominant cytokine responses, and enhanced DCs, CD4+ and CD8+ T-cell activation. The cocktail vaccine conferred superior protection compared to single-antigen formulations, significantly improving survival and reducing cyst formation. Co-administration of pVAX-IL-28B further augmented vaccine-induced immunity, enhancing both cellular and humoral responses. Moreover, these DNA immunization with pVAX-GRA28 and pVAX-GRA83 plus pVAX-IL-28B induced robust protective immunity that was largely independent of type I IFN signaling, consistent with type III IFN biology. Conclusions: Our findings demonstrate that TgGRA28 and TgGRA83 are promising vaccine candidates against toxoplasmosis, capable of inducing protective immunity against acute and chronic infection. Moreover, IL-28B serves as a potent genetic adjuvant, warranting further investigation for its broader application in vaccines targeting apicomplexan parasites. Full article

To address the critical issue of low reliability caused by fault impacts in large-scale wind farms transmitting power over long distances via flexible DC transmission systems, this study proposes a collaborative solution. First, a new protection scheme integrating variable quantity differential protection, steady-state quantity differential protection and zero-sequence differential protection is proposed. By establishing a refined model of a wind farm with a flexible DC system, the adaptability of the differential protection for the outgoing lines is checked. Simulation results show that the sensitivity of metallic faults within the protection zone is better than 3.0, and the protection reliably remains inactive for faults outside the protection zone. Second, an innovative fault ride-through strategy combining self-regulating resistor circuits with wind farm MPPT load reduction is proposed. During faults on the receiving grid, the DC voltage fluctuation is controlled within 1.05 p.u. through graded switching of resistor modules and dynamic power regulation. This solution offers both rapid response and smooth fault ride-through characteristics, significantly improving the feasibility and economic viability of wind farm integration via flexible DC transmission. Full article

Cyber-physical power systems integrate sensing, communication, and control, ensuring power system resiliency and security, particularly in clustered networked microgrids. Software-Defined Networking (SDN) provides a suitable foundation by centralizing policy, enforcing traffic isolation, and adopting a deny-by-default policy in which only explicitly authorized flows are admitted. This paper proposes and experimentally validates a cyber-physical architecture that couples three DC microgrids through an SDN backbone to deliver rapid, reliable, and secure power sharing under highly dynamic conditions, including pulsed-load disturbances. The cyber layer comprises four SDN switches that establish dedicated paths for protection messages, supervisory control commands, and high-rate sensor data streams. An OpenFlow controller administers flow-rule priorities, link monitoring, and automatic failover to preserve control command paths during disturbances and communication faults. Resiliency is further assessed by subjecting the network to a deliberate denial-of-service (DoS) attack, where deny-by-default policies prevent unauthorized traffic while maintaining essential control flows. Performance is quantified through packet captures, which include end-to-end delay, jitter, and packet loss percentage, alongside synchronized electrical measurements from high-resolution instrumentation. Results show that SDN-enforced paths, combined with coordinated multi-microgrid control, maintain accurate power sharing. A validated, hardware testbed demonstration substantiates a scalable, co-designed communication-and-control framework for next-generation cyber-physical DC multi-microgrid deployments. Full article

DC distribution networks exhibit inherent symmetry in their balanced power distribution and modular structure, offering high operational flexibility and making them particularly suitable for the integration of distributed generation and modern loads. This symmetric framework positions DC networks as a vital component of new power systems and a key development direction for future power supply systems in industrial and mining enterprises. However, pole-to-pole short-circuit faults disrupt this symmetry, characterized by low system damping, high fault currents, and extremely rapid current rise rates, which pose serious threats to system security and necessitate ultra-fast fault clearance. To address this issue, this paper proposes a novel pilot protection scheme inspired by symmetry principles, based on the slope of the line-mode current for pole-to-pole short-circuit faults in DC distribution networks. First, an equivalent circuit of the system before converter blocking under a pole-to-pole fault is established, and an analytical expression of the fault current is derived, incorporating symmetric analysis of modal components. Subsequently, the variation trends, amplitudes, and phase characteristics of the fault current under faults occurring in different zones of the DC line are analyzed from the perspective of modal symmetry, highlighting the symmetric and asymmetric behaviors of line-mode and zero-mode currents. Furthermore, considering the distinct symmetric properties of these currents during lightning disturbances and pole-to-pole faults, the least squares method is employed to perform linear fitting on the line-mode current, thereby capturing its symmetric variation trend. A pilot protection scheme utilizing the slope of the line-mode current is then proposed, leveraging symmetry in fault discrimination. Finally, simulation models built in MATLAB/Simulink (R2022a) are used for validation. The results demonstrate that the proposed protection method can quickly identify faults within 1.5 ms while exhibiting strong tolerance to a 20 Ω transitional resistance and 50 dB signal noise, indicating good feasibility and broad applicability, with symmetry-based analysis enhancing robustness. Full article

Sonneratia ovata is an important tree species for ornamental, economic, ecological, and medicinal value and is identified as an endangered species. There are very few studies on the reproductive traits, genetic diversity, and population structure of S. ovata. Therefore, it is urgent to accurately understand its genetic background and reproductive status in order to better conserve and manage S. ovata. S. ovata has a mixed mating system, is partially self-compatible and needs pollinators, according to the outcrossing index, pollen–ovule ratio, pollination treatment results and outcrossing rate. Natural populations maintained high outcrossing coupled with inbreeding and low genetic diversity (H_e = 0.215), and the population DC was regarded as the center of genetic diversity. The Mantel test showed that there existed a positive correlation between geographic and genetic distance among populations, which was in line with the IBD model. Molecular variance was largely confined to within-population differences (75.4%), while inter-population differences accounted for 24.6%. Structure and PCoA analysis supported the UPGMA cluster. This study is the first to investigate reproductive traits, genetic diversity, and population structure through SSR. The results provide a scientific basis for cross breeding, conservation, and management of this species. In future, it is necessary to increase relevant research (human, environment, habitat factors, etc.) to better protect and utilize this species. Full article

Under the context of global climate change and China’s dual carbon strategy (DCS), the impact of land use/land cover change (LULCC) on regional carbon stocks has garnered increasing attention. As a key economic and ecological hub in Southwest China, Chengdu has undergone significant urbanization over the past two decades, and it is necessary to quantitatively assess how shifts in land use affect its carbon stock function. This study integrates multi-period remote sensing data from 2000 to 2020, combining socioeconomic and natural environmental drivers. The PLUS model was employed to simulate land use in 2030 under four scenarios: Natural Development Scenario (NDS), Urban Development Scenario (UDS), Conservation of Cropland Scenario (CPS), and Ecological Protection Scenario (EPS). The InVEST model was then used to calculate changes in carbon stocks and their spatial distribution characteristics. The results indicate the following: (1) From 2000 to 2020, Chengdu’s cropland decreased by 1188.6174 km², while built-up land increased by 1006.5465 km², resulting in a net carbon stock decrease of approximately 3.25 × 10⁶ t, with carbon gains from forest restoration offsetting part of the cropland-to-built-up loss; (2) Under all scenarios, built-up land exhibited an expansion trend, with the UDS showing the most significant increase, reaching 1919.2455 km². In the EPS, the forest increased to 4035.258 km², achieving the largest carbon stock increase of 8.5853 × 10⁶ t. (3) Chengdu’s carbon stock exhibits a spatial distribution pattern characterized by “high in the northwest, low in the center”. High-value areas are concentrated in the ecologically sound Longmen Mountains and Longquan Mountains, while low-value areas are primarily located in urban built-up zones and their peripheries. The study indicates that rationally controlling the expansion of Built-up land, strengthening ecological restoration, and protecting forests can effectively enhance Chengdu’s carbon sink capacity and achieve regional low-carbon and sustainable development. This study aims to address the gap in carbon stock assessments under different development scenarios at the urban scale in Southwest China, and to provide a scientific basis for Chengdu’s regional spatial planning, ecological conservation, low-carbon development, and sustainable land management. Full article

Background: Aβ1-42 and APOE concentrations, as well as Aβ42/40 ratio, may be considered as a link between hypertension (HTN) or diabetes mellitus (DM), brain amyloidosis, and dementia. HTN and DM are associated with cognitive impairment and may contribute to the development of Alzheimer’s disease (AD). This preliminary study aimed to evaluate the impact of vascular risk factors on the concentration of biochemical AD markers and cognitive state. As it is a cross-sectional study in nature, causal relationships cannot be established. Methods: The study was conducted in the south of Poland among a rural population over 65 years of age. A total of 58 patients qualified into the study were divided into groups according to the presence of HTN (n = 18) or HTN coexisting with DM (n = 40). A healthy control group was also formed (n = 20), resulting in 78 study participants. The study population was also divided based on M-ACE results, forming a normal cognition group (NC) and a deteriorated cognition group (DC). Biochemical tests, neurological scales assessments, and ultrasound examinations were conducted. Results: Patients who scored in the normal range on the M-ACE had higher Aβ1-42 (median 38.52 vs. 27.35 pg/mL, p = 0.02) and apoE concentrations (median 125.0 vs. 65.73 μg/mL, p = 0.002), and a higher Aβ42/40 ratio (median 0.39 vs. 0.29 p < 0.000) compared to the DC group. Considering the study groups, the highest Aβ42/40 ratio was found among the HC group (median 0.47). The median score for the M-ACE scale was 3 points lower when HTN and DM coexisted, compared to the sole diagnosis of HTN (25 points and 28 points, respectively). A higher number of years of education correlated with better M-ACE results. Lipid and uric acid concentrations were not related to M-ACE or MMSE scores. An inverse relationship connected Aβ1-40 and Aβ1-42 to BMI, the duration of HTN treatment, and glycated hemoglobin. Conclusions: Aβ1-42, APOE, and Aβ42/40 are not only correlated with cognition but also related to patient’s disease profile. The coexistence of DM and HTN was associated with the most significant decline in cognitive functioning. However, a higher number of years of education may protect against the development of dementia in old age. The roles of cholesterol and uric acid in cognitive decline are still inconclusive. Full article

Low-voltage power converters in the 25–200 V range are increasingly employed in emerging applications such as hybrid electric vehicles (HEVs), photovoltaic systems with battery storage, and electric propulsion systems for recreational boats. In these contexts, 48 V battery systems have become standard, due to safety considerations. Among various converter topologies, H-bridge configurations operating around 100 V DC are widely used in laboratory-scale prototyping. While MOSFETs are the preferred switching devices in this voltage range, due to their high efficiency and fast switching characteristics, they also introduce design challenges related to high current slew rates and associated overvoltage spikes caused by parasitic inductances in the PCB layout. These overvoltages, though modest in absolute terms, can be critical in low-voltage systems, due to the lower device ratings. This paper presents design strategies and layout best practice for a 120 V, 50 A H-bridge converter using 200 V rated MOSFETs. The effectiveness of various mitigation techniques—including the use of ceramic capacitors in parallel with film and electrolytic types, Schottky diodes across MOSFETs, and snubber circuits—is evaluated and experimentally validated on a dedicated prototype. The results highlight the critical role of PCB design in ensuring switching reliability and device protection in low-voltage converter systems. In addition, with the design solutions shown in this study, it was possible to obtain a voltage overshoot during switching of just 165 V with a 120 V DC-link voltage, which guarantees a sufficient safety margin for the MOSFET rated voltage. Full article

In high-voltage transmission systems, current transformers (CTs) are susceptible to core saturation when subjected to DC bias, which leads to severe distortion of the secondary output current, affecting protection and metering accuracy. In order to solve this problem, this paper proposes a CT distortion current inverse derivation method based on long short-term memory (LSTM) neural network. The method takes the secondary current (referred to the primary side) as input, models its temporal structure with an LSTM, and outputs the corresponding estimate of the true primary current. First, the simulation model considering DC bias effect is built in PSCAD to generate training samples; then, the LSTM network structure is designed, and finally, the training samples are trained and the inverse derivation results are generated. Simulation results demonstrate accurate recovery of the primary current across saturation levels and DC-bias magnitudes, reducing RMSE by 66.29% and 79.54%, and MAE by 44.12% and 72.06%, relative to an SVM and a shallow ANN, respectively, indicating strong generalization and robustness. Full article

Stray currents leaking from electrified DC rail systems cause the greatest corrosion risk to underground metal gas pipelines and can lead to pipeline wall perforation in a very short time. Leakage and gas explosion, and other direct and indirect effects, can even disrupt the stability of the energy system. Maintaining the reliability of gas pipelines, therefore, requires protecting them against corrosion caused by stray currents. It is therefore necessary to conduct field studies to identify sections of gas pipelines at risk and where protective installations should be installed. The paper discusses the most important field methods for assessing the risk of stray currents to gas pipelines: the potential of rail traction relative to ground, electric field gradients in the ground associated with stray current flow, correlation of gas pipeline potential and voltage of pipeline vs. the rail, and time-frequency analysis of the pipeline and rail potentials. A typical application case for each method is indicated, and the advantages and disadvantages of each research technique are identified. The criterion for selecting methods for this review was a short measurement duration (tens of minutes), after which it is possible to determine the level of the hazard to the gas pipeline caused by stray currents in the examined location. This is why these methods have an advantage over other research techniques that require long-term monitoring or exposure of probes or sensors. The review will be useful for cathodic protection personnel involved in the operation of gas pipelines and may be helpful in developing new methods for assessing the impact of stray currents. Full article