Direct Transmission Research Articles

Simulation of the dynamical transmission of 100 eV positrons through a conical capillary

The simulation of 100 eV positrons transmitted in conical capillary was performed with inserted beam intensity from 0.04 fA/mm2 to 10 fA/mm2. At lower injected intensity of sub-fA, the transmission profile is geometrical and dominated by direct transmission. As the tilt angle increases, the intensity of the transmitted positron decreases rapidly, which is consistent with the experimental data. After increasing injected current intensities to several fA/mm2, charge deposited in the capillary significantly enhances the transmission rate, and the positrons can transmit the capillary with larger tilt angles. The transmitted current density is shown to increase up to a factor of 4.8 with respect to the injected one. These results provide evidence that the low-energy positrons can be guided and significantly focused by insulating conical capillary.

A current injection method for converter power loss representation in electromagnetic transient simulation

The power-electronics converters are increasingly applied in modern power system, which contains various sub-systems, such as renewable energy power plants and high voltage direct current transmission systems, etc. The electromagnetic transient simulation has been one of the important tools for the study of complex system containing large numbers of power converters. The coordination control of the power converters and corresponding power generation and load units is one of the challenges ensuring stability and obtaining optimal efficiency. However, the detailed modeling of the power converters considering the conduction and switching losses can cost a great number of computation resources, which makes it difficult to simulate a large system. This work proposed a current injection method for converter power loss representation, which can accurately consider the conduction and switching losses of the power-electronics switches with low computation complexity. A look-up table (LUT) of the power loss ratio is calculated before the simulation, and a current source representing the power loss is connected in parallel with the converter to track the reference loss generated by the look-up table. The proposed method can be combined with multiple converter modeling schemes, such as the two-resistance model, the switching-function model, and the average value model, etc. The topologies of the two-level converter and the modular multi-level converter (MMC) were used in the case studies to demonstrate the effectiveness of the proposed method. Compared to the device-level model, the simulation power loss deviation is 0.64% and 4.13% applying the current injection method model in the case studies of the two-level converter and the MMC.

AI & Physics-Based Bad Command/Data Detection in Large Power Electronics Systems: Multi-Port Autonomous Reconfigurable Solar Power Plant (MARS)

Detection of bad data from measurement sensors and bad commands from control centers need to be carried out to avoid instabilities within large power electronics systems. Towards the same, in this paper, model and data driven methods are proposed to identify anomalies in measured data and commands received by large power electronics systems. The large power electronics system considered in this paper is a multi-port autonomous reconfigurable solar power plant (MARS), which consists of photovoltaic (PV) and energy storage systems (ESSs) that connect to high-voltage direct current (HVdc) system and transmission ac power grid. The proposed algorithms in the MARS power plant to detect bad data from measurements and bad commands from control centers are evaluated in simulations and hardware-in-the-loop (HIL) tests. It has been observed that the proposed algorithms are able to detect bad measurements and commands in all the use cases evaluated.

Dual-Arm Modular Multilevel Converter With a Compact Footprint for VSC-HVDC Applications

In this paper, a novel dual-arm modular multilevel converter (DAC) with inherent DC-fault-blocking capability is proposed that needs only two stacks of submodules (SMs), as well as director switches (DSs), for multilevel AC/DC conversion. Compared to the state-of-the-art modular multilevel converter (MMC) technologies with six SM-based arms, the DAC's dual multiplexed converter arm structure, combined with needing approximately 75% less capacitive energy storage than the MMC, facilitate a smaller converter station footprint. This paper presents the operating principle of the DAC and benchmarks it against other voltage source converter technologies based on converter functionalities, component count, capacitive energy storage requirements, and semiconductor losses for high voltage direct current transmission (HVDC) application. For a wider output voltage range, overlap operation is proposed to enable circulating currents to balance the SM capacitors' energy cycle-to-cycle. A 600 kV HVDC system simulation study is presented that demonstrates the DAC's ability to (1) transmit power bidirectionally under nominal conditions, and (2) extinguish fault currents during DC-side short-circuit fault. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$200\,V_\rm{DC}$</tex-math></inline-formula> scaled-down converter hardware implementation further verifies the DAC's operating principle.

Out-of-Band Information Aided mmWave/THz Beam Search: A Spatial Channel Similarity Perspective

The transition to higher frequency bands, e.g., millimeter-wave (mmWave) and terahertz (THz), will be capitalized on the long term for future wireless communications. One of challenges relates to rapid establishment of mmWave/THz links with low beam training overhead due to highly directional transmission. A promising solution is to take advantage of the coexistence of sub-6 GHz, mmWave, and THz wireless networks and to use out-of-band spatial information for enabling fast beam search. The success depends on the spatial similarity of radio channels across different frequency bands. In this article we promote a feasibility study of low-frequency spatial channel information assisted high-frequency beam search from a radio channel point of view. We develop multi-band channel similarity measure of desired beam directions extracted from radio channels, which are obtained via filtering propagation paths by different beampatterns at different frequencies. Measurementand ray-tracing-based evaluations across multiple frequencies and environments are performed, which prove the usability of out-of-band information aided beam search strategy in line-ofsight (LOS) dominated scenario and even in non-LOS scenario. Finally, we discuss the challenges associated with exploiting spatial channel similarity.

Design of directional transmission channel models for breast photoacoustic signals based on defect state structure

In the photoacoustic detection of breast cancer, the weak intensity and severe energy attenuation of photoacoustic signals excited by the breast tissue become an important factor limiting the efficient acquisition of the ultrasound transducer. To overcome this problem, we proposed a linear defect channel and bifurcated acoustic transmission channel models at the front of the ultrasonic transducers based on the phononic crystal bandgap characteristics and defect state structure. The results of numerical analyses and simulations carried out using COMSOL demonstrated that the photoacoustic signal transmission channel proposed could confine the acoustic energy within the defects, while achieving the directional transmission and local enhancement of the acoustic field of high-frequency breast photoacoustic signals. This design effectively reduces the signal transmission loss and amplifies the mammographic signal intensity, which is conducive to efficient acquisition. In addition, the directional transmission effect is found to be strongly dependent on frequency, which makes the channel have great frequency selectivity. Through the flexible modulation of the transmission path of the artificial acoustic structure, breast photoacoustic signals of specific frequencies can be exported in separate paths to reduce the interference of noise signals. This study combines biomedical tumor detection with phononic crystals to present a novel method for efficient acquisition and deep detection of acoustic signals in tissue photoacoustic detection from the signal perspective, which is conducive to improving the sensitivity of breast cancer detection.

The Channel Fading Influence of the Receiver Operating Characteristics of the TT&amp;C Receiver Based on the Dual-Sequence Frequency Hopping

Aimed at the antijamming needs of the space tracking, telemetry command (TT&amp;C) receiver under a low signal-to-noise ratio, the anti-interference advantage of the dual-sequence frequency hopping (DSFH) communication system is applied. The channel amplitude fading influence of the receiver operating characteristics (ROC) of the TT&amp;C receiver based on the DSFH is studied. Firstly, based on the typical channel model of the Rayleigh fading without direct path transmission, the conditional Fokker-Planck equation (FPE) is obtained by analyzing the statistical independence of the Rayleigh fading signal and SR output particle moments. Secondly, the probability density function (PDF) of the DSFH signal via channel Rayleigh fading enhanced by stochastic resonance (SR) is obtained by introducing the decision time. Thirdly, the detection probability, false alarm probability, ROC, and system bit error rate (BER) of the DSFH signals enhanced by SR under the Rayleigh fading conditions are obtained, under the minimum BER criterion. Finally, the conclusions are reached: one is that the DSFH signals via channel Rayleigh fading can still be detected by the SR system under low SNR, and the other one is that the SNR can reach the -13 dB by the reception of DSFH signal enhanced by SR, when the Rayleigh fading parameter is 0.2042.

Superhydrophobic NiTi shape memory alloy arrays with switchable controlled anisotropic droplet sliding

Smart microstructured surfaces have attracted extensive attention in recent years, because the surface microstructure morphology can be tuned using an external field to change the wettability. Inspired by the surface microstructures of butterfly wings, a tilted array microstructure was fabricated on the surface of NiTi shape memory alloy (NiTi-SMA) using wire electrical discharge machining (WEDM). The modified surface with fluorosilane showed superhydrophobicity and anisotropic droplet sliding. As the shape of the tilted microarray structure could be repeatedly switched between the original shape and deformation under the action of force and heat, the contact angle of the surface was repeatedly switched between 155.9° ± 0.2° and 150.3° ± 0.3°, and the anisotropic sliding angle of the surface was repeatedly switched between 7.9° ± 1.6° and 22.9° ± 1.3°, and 19.6° ± 0.6° and 53.4° ± 2.9°. The range of switchable anisotropic sliding could be adjusted by changing the microstructure spacing L. In addition, the surface of the tilted microarray structure showed a directional water transport ability under the action of vibrations, and the directional transmission of water droplets could be selectively controlled by changing the morphology of the surface microstructure. Therefore, a smart surface with switchable wettability was realized on the NiTi-SMA surface, providing a new method to realize the smart control of droplets on smart microstructured surfaces.

Skin Care Experience of a Case of Multiple Organ Failure Caused by High-Voltage Electrical Injury

Background: High-voltage electrical burns are caused by the direct transmission of electric current through the body and the conversion of electric energy into heat energy, which directly heats the tissues and leads to organ function damage. Especially after high-voltage electric burns (more than 1000W), it can not only cause coagulation necrosis of the skin and even carbonization, but also cause serious deep tissue damage .The degree of tissue damage depends on the type of current, the magnitude of current, the frequency, the voltage, the resistance of the tissue, the skin humidity, the duration, the contact area, and other factors. Low voltage and low frequency electric shock mainly affect the heart and respiration, which can lead to insignificant soft tissue damage. High voltage electric shock mainly causes serious soft tissue damage, which can be accompanied by changes in the circulatory system and respiratory system.[1] Subject and Method: We collected the data of a case of multiple organ failure caused by high-voltage electricity that was successfully treated in July 2023.In the course of this patient's successful treatment, The main nursing measures were analyzed: The intake and output volume were actively controlled. Albumin supplementation, Debridement and dressing change were performed daily, Covered with nano-silver ion dressing, Try to ensure a sterile environment during operation, Maintain ambient temperature and humidity. Results: Twenty days later,the skin damage caused by electric burns was reduced from 30% to 1%. Conclusion: These are very important links: The intake and output volume were actively controlled, The balance of intake and output was maintained for 24 hours, and lactic acid was less than 2mmol/L. Albumin supplementation Controlled above 30g/L, Debridement and dressing change were performed daily, Covered with nano-silver ion dressing, Try to ensure a sterile environment during operation, Maintain ambient temperature 28~30℃ and humidity 40%~50%.

Linear Potentiometer Sensor-Based of Athlete Flexibility Measurement Tool

This study aims to develop a novel "sit and reach test" flexometer device utilizing a linear potentiometer sensor to quantitatively evaluate an individual's body flexibility. The innovation in this research lies in the utilization of electronic means to measure flexibility, replacing conventional manual methods. The device employs a linear potentiometer sensor that translates analog voltage into a digital value (ADC) and subsequently converts the digital data into distance measurements in centimeters (cm). The processed data, representing the distance measurements, is wirelessly transmitted to a personal computer (PC) for automatic capture and analysis. The design considerations prioritize modernity, practicality, effectiveness, and efficiency. The experimental outcomes demonstrate the efficacy of the developed tool. The readings from the linear potentiometer sensor exhibit a high linearity, indicated by an R2 value of 0.9999. The average error percentage is minimal, measuring at 0.17%. Moreover, the device allows for direct wireless transmission of data to a PC immediately after assessing an athlete's flexibility. This study not only introduces a novel electronic approach for assessing body flexibility but also validates its accuracy and efficiency through comprehensive testing and analysis.

Increase in invasive group A streptococcal infections in Milan, Italy: a genomic and clinical characterization.

Group A Streptococcus (GAS) causes multiple clinical manifestations, including invasive (iGAS) or even life-threatening (severe-iGAS) infections. After the drop in cases during COVID-19 pandemic, in 2022 a sharp increase of GAS was reported globally. GAS strains collected in 09/2022-03/2023 in two university hospitals in Milan, Italy were retrospectively analyzed. Clinical/epidemiological data were combined with whole-genome sequencing to: (i) define resistome/virulome, (ii) identify putative transmission chains, (iii) explore associations between emm-types and clinical severity. Twenty-eight isolates were available, 19/28 (67.9%) from adults and 9/28 (32.1%) from pediatric population. The criteria for iGAS were met by 19/28 cases (67.9%), of which 11/19 (39.3%) met the further criteria for severe-iGAS. Pediatric cases were mainly non-invasive infections (8/9, 88.9%), adult cases were iGAS and severe-iGAS in 18/19 (94.7%) and 10/19 (52.6%), respectively. Thirteen emm-types were detected, the most prevalent being emm1 and emm12 (6/28 strains each, 21.4%). Single nucleotide polymorphism (SNP) analysis of emm1.0 and emm12.0 strains revealed pairwise SNP distance always >10, inconsistent with unique transmission chains. Emm12.0-type, found to almost exclusively carry virulence factors speH and speI, was mainly detected in children and in no-iGAS infections (55.6 vs. 5.3%, p = 0.007 and 66.7 vs. 0.0%, p < 0.001, respectively), while emm1.0-type was mainly detected in severe-iGAS (0.0 vs. 45.5%, p = 0.045). This study showed that multiple emm-types contributed to a 2022/2023 GAS infection increase in two hospitals in Milan, with no evidence of direct transmission chains. Specific emm-types could be associated with disease severity or invasiveness. Overall, these results support the integration of classical epidemiological studies with genomic investigation to appropriately manage severe infections and improve surveillance.

Multidrug-Resistant Bacteria Contaminating Plumbing Components and Sanitary Installations of Hospital Restrooms.

Antimicrobial resistance (AMR) poses several issues concerning the management of hospital-acquired infections, leading to increasing morbidity and mortality rates and higher costs of care. Multidrug-resistant (MDR) bacteria can spread in the healthcare setting by different ways. The most important are direct contact transmission occurring when an individual comes into physical contact with an infected or colonized patient (which can involve healthcare workers, patients, or visitors) and indirect contact transmission occurring when a person touches contaminated objects or surfaces in the hospital environment. Furthermore, in recent years, toilets in hospital settings have been increasingly recognised as a hidden source of MDR bacteria. Different sites in restrooms, from toilets and hoppers to drains and siphons, can become contaminated with MDR bacteria that can persist there for long time periods. Therefore, shared toilets may play an important role in the transmission of nosocomial infections since they could represent a reservoir for MDR bacteria. Such pathogens can be further disseminated by bioaerosol and/or droplets potentially produced during toilet use or flushing and be transmitted by inhalation and contact with contaminated fomites. In this review, we summarize available evidence regarding the molecular features of MDR bacteria contaminating toilets of healthcare environments, with a particular focus on plumbing components and sanitary installation. The presence of bacteria with specific molecular traits in different toilet sites should be considered when adopting effective managing and containing interventions against nosocomial infections potentially due to environmental contamination. Finally, here we provide an overview of traditional and new approaches to reduce the spreading of such infections.

Educational Soft Underwater Robot with an Electromagnetic Actuation.

As demonstrated by the Soft Robotics Toolkit Platform, compliant robotics pose an exciting educational opportunity. Underwater robotics using soft undulating fins is an expansive research topic with applications such as exploration of underwater life or replicating 3d swarm behavior. To make this research area accessible for education we developed Educational Soft Underwater Robot with Electromagnetic Actuation (ESURMA), a humanoid soft underwater robot. We achieved advances in simplicity, modularity, and performance by implementing electromagnetic actuation into the caudal fin. An electromagnet, including electronics, is placed in a waterproof housing, and permanent magnets are embedded in a soft silicone cast tail. The force from their magnetic interaction results in a bending movement of the tail. The magnetic actuation is simple to implement and requires no mechanical connection between the actuated component and the electrically controlled coil. This enables robust waterproofing and makes the device fully modular. Thanks to the direct and immediate transmission of force, experimental flapping frequencies of 14 Hz were achieved, an order of magnitude higher compared to pneumatically actuated tails. The completely silent actuation of the caudal fin enables a maximum swimming speed of 14.3 cm/s. With its humanoid shape, modular composition, and cost efficiency ESURMA represents an attractive platform for education and demonstrates an alternative method of actuating soft structures.

Multi‐Length Scale Communication Effects in Catalysis: Thinking Big and Acting Small

AbstractThe use of hierarchically structured materials as catalysts has been finding increasing application in the past years. For these catalytic systems, not only the nano‐scale matters: a high degree of order across multiple length scales, along with its control and analytical assessment, is of paramount importance to obtain innovative properties that can find application in catalysis. Most reviews dealing with hierarchically structured materials are concerned with the “bottom‐up” transfer of structural information along the different length scales, with special emphasis on the transmission of chirality. Due to their mesoscale size together with their complex behaviour, these systems are often susceptible to feel the effects of macroscopic forces, that can exert a “top‐down” control of their catalytic properties, so that an external stimulus, acting at the level of the supramolecular architecture of the catalyst, can ultimately determine the outcome of the catalyzed reaction at the molecular level. We review in this paper some recent reports that deal with the experimental implementation of this concept, either by using a mechanical force in a full range direct transmission to the reaction coordinate, or by means of a stepwise relay transmission from the macroscopic level (purely supramolecular chirality) to the nanoscopic one. We focus in this review on these multi‐length scale communication control effects, identifying the different mechanisms that are affecting the catalytic activity.

Modeling and experimental validation of a proposed distance protection system for MVDC transmission lines

Protecting direct current transmission lines (DC-TLs) against faults is challenging and crucial, especially when locating faults. This research aims to develop a novel distance protection approach for Medium voltage direct current transmission lines (MVDC-TLs). Various faults in the computerized experiments and practical models have been applied to the proposed system in the AC network and DC transmission lines to evaluate the performance of the proposed method. The proposed protection system employs the wavelet transforms (WT) and ANFIS as detailed coefficients ‘feature extracting’ tools and classifiers, respectively. The mechanism operation of the proposed method is composed of three stages. Firstly, it extracts the features of the faults by WT. Hence, the ANFIS training process uses such features to identify and classify the faults. The third stage utilizes the ratio value between the fault current and the healthy operation current as an input of another ANFIS model to locate faults on the DC TL. The performance of the proposed protection method has been tested and evaluated for MVDC and MVAC networks. Also, the research executes both practical and simulation experiments utilizing different faults. It examines various fault locations on the entire MVDC line. The mechanism measures the current signals on both sides of the DC-TL. The paper built the MVDC-TLs model and the different cases using the software PSCAD/EMTDC and the proposed method via MATLAB. The study tested faults along the TL in the presence of the AWGN noise. The research utilizes practical experiments to verify the accuracy of the proposer. The accuracy of the proposed fault location is 99.923 %. Based on the results of this research paper and comparison with the recent related research works, the proposed method is more effective and efficient than the previous methods in detecting, classifying, and locating system faults.

Prevalence of Astroviruses in Different Animal Species in Poland.

Astroviruses (AstVs) are small RNA viruses characterized by a high mutation rate, the ability to recombine, and interspecies transmission, which allows them to infect a multitude of hosts including humans, companion animals, and farmed animals as well as wildlife. AstVs are stable in the environment, and their transmission is usually through the fecal-oral route or via contaminated water and food. Although direct zoonotic transmission was not confirmed, interspecies transmission events have occurred or have been indicated to occur in the past between wild and domestic animals and humans. They cause large economic losses, mainly in the poultry sector, due to gastroenteritis and mortality. In young children, they are the second most common cause of diarrhea. This study involved 166 intestine samples and pools of spleen, lymph node, and kidney samples collected from 352 wild animals, 52 pigs, and 31 companion animals. Astroviruses were detected in the intestine samples and were separately detected in pools of tissue samples prepared for individual animals using a heminested RT-PCR protocol. Amplicons were subjected to Sanger sequencing, and a phylogenetic analysis of 320 nt RNA-dependent RNA polymerase (RdRp) fragments referring to known nt sequences of astroviruses was performed. Astroviral RNA was detected in the intestine samples and/or tissue pools of red foxes (nine positive intestines and six positive tissue pools), rats (two positive intestines and three positive tissue pools), a cat (one AstV detected in an intestine sample), pigs (eight positive tissue pools), and wild boars (two positive pools of spleens, kidneys, and lymph nodes). No astroviral RNA was detected in wild mustelids, dogs, or other small wild animals including rodents. A phylogenetic analysis revealed that the astroviruses detected during this study were mostly host-specific, such as porcine, canine, and rat astroviruses that were highly homologous to the sequences of reference strains. In one of two wild boars, an AstV distinct to porcine species was found with the highest nt identity to Avastroviruses, i.e., turkey astroviruses, which suggests potential cross-species transmission of the virus, as previously described. Here, we present the first detection of astroviruses in the population of wild animals, companion animals, and pigs in Poland, confirming that astroviruses are frequent pathogens circulating in animals in the field. Our study also suggests potential cross-species transmission of Avaastrovirus to wild boars; however, further molecular characterization is needed.

Wildlife vaccination strategies for eliminating bovine tuberculosis in white-tailed deer populations.

Many pathogens of humans and livestock also infect wildlife that can act as a reservoir and challenge disease control or elimination. Efficient and effective prioritization of research and management actions requires an understanding of the potential for new tools to improve elimination probability with feasible deployment strategies that can be implemented at scale. Wildlife vaccination is gaining interest as a tool for managing several wildlife diseases. To evaluate the effect of vaccinating white-tailed deer (Odocoileus virginianus), in combination with harvest, in reducing and eliminating bovine tuberculosis from deer populations in Michigan, we developed a mechanistic age-structured disease transmission model for bovine tuberculosis with integrated disease management. We evaluated the impact of pulse vaccination across a range of vaccine properties. Pulse vaccination was effective for reducing disease prevalence rapidly with even low (30%) to moderate (60%) vaccine coverage of the susceptible and exposed deer population and was further improved when combined with increased harvest. The impact of increased harvest depended on the relative strength of transmission modes, i.e., direct vs indirect transmission. Vaccine coverage and efficacy were the most important vaccine properties for reducing and eliminating disease from the local population. By fitting the model to the core endemic area of bovine tuberculosis in Michigan, USA, we identified feasible integrated management strategies involving vaccination and increased harvest that reduced disease prevalence in free-ranging deer. Few scenarios led to disease elimination due to the chronic nature of bovine tuberculosis. A long-term commitment to regular vaccination campaigns, and further research on increasing vaccines efficacy and uptake rate in free-ranging deer are important for disease management.

Research on influencing factors of emergency power support for voltage source converter-based multi-terminal high-voltage direct current transmission system

Research on influencing factors of emergency power support for voltage source converter-based multi-terminal high-voltage direct current transmission system

Comparing a Multi-Terminal High Voltage Direct Current and Unified Power Flow Control for Short Circuit Level Reduction in Iraqi 400 Kv Grid

The demand for electricity has increased significantly in recent years; yet, the transmission and distribution networks are unable to meet unrestrained demands because of resource constraint. Losses in power lines exacerbate the unfavorable conditions for maximum power transfer. Recent decades have seen a rise in the use of FACTS and High Voltage Direct Current transmission in power systems due to its many advantages, which include reduced short circuit level (SCL), enhanced voltage profiles, reduced network power losses, and enhanced system reliability and safety. The paper presents a comparing study of the effectiveness of Unified Power Flow Control (UPFC) and Multi-Terminal High Voltage Direct Current (MT-HVDC) transmission in reducing short circuit current and network power losses for the Iraqi Super High Voltage (ISHV) grid. Modeling of Unified Power Flow Control and Multi-Terminal High Voltage Direct Current transmission is carried out using the Power System Simulator for Engineering (PSS/E) version 32 Package Program. The integration of multi-terminal HVDC transmission to the system resulted in a considerable decrease in short circuit levels and network power losses for the majority of buses in the system, as well as a reduction in the loading on the transmission lines in the southern region of Iraqi Super High Voltage grid, As a result, the South’s network performance will improve, hence improving Iraq’s electrical power system. Furthermore, when compared to installing a UPFC, the results showed that multi-terminal HVDC transmission reduces short circuit levels more efficiently.

Determining the effect of contaminated environment and direct transmission on the dynamics of monkeypox virus

Determining the effect of contaminated environment and direct transmission on the dynamics of monkeypox virus