Generation Of Devices Research Articles

Microstructured large-area photoconductive terahertz emitters driven at high average power

Emitters based on photoconductive materials excited by ultrafast lasers are well-established and popular devices for THz generation. However, so far, these emitters – both photoconductive antennas and large area emitters - were mostly explored using driving lasers with moderate average powers (either fiber lasers with up to hundreds of milliwatts or Ti:Sapphire systems up to few watts). In this paper, we explore the use of high-power, MHz repetition rate Ytterbium (Yb) based oscillator for THz emission using a microstructured large-area photoconductive emitter, consist of semi-insulating GaAs with a 10 × 10 mm2 active area. As a driving source, we use a frequency-doubled home-built high average power ultrafast Yb-oscillator, delivering 22 W of average power, 115 fs pulses with 91 MHz repetition rate at a central wavelength of 516 nm. When applying 9 W of average power (after an optical chopper with a duty cycle of 50%) on the structure without optimized heatsinking, we obtain 65 µW THz average power, 4 THz bandwidth; furthermore, we safely apply up to 18 W of power on the structure without observing damage. We investigate the impact of excitation power, bias voltage, optical fluence, and their interplay on the emitter performance and explore in detail the sources of thermal load originating from electrical and optical power. Optical power is found to have a more critical impact on large area photoconductive emitter saturation than electrical power, thus optimized heatsinking will allow us to improve the conversion efficiency in the near future towards much higher emitter power. This work paves the way towards achieving hundreds of MHz or even GHz repetition rates, high-power THz sources based on photoconductive emitters, that are of great interest for example for future THz imaging applications.

Bioanode boosts efficacy of chlorobenzenes-powered microbial fuel cell: Performance, kinetics, and mechanism

Microbial fuel cell (MFC) is a promising device for water decontamination and energy generation. However, the correlation between power generation and pollutant degradation has not been clarified. Herein, a ruthenium–activated carbon (Ru–AC) bioanode was constructed for chlorobenzenes (CBs) treatment. The pollutant tolerance was improved by Ru–AC anode, and the minimum removal efficiencies of CB and ortho-dichlorobenzene (o-DCB) reached 75.1 % and 69.3 %, respectively, which were considerably higher than those of other MFCs (16.3 %–39.7 %). Correspondingly, the maximum output voltage reached 360.7 mV for the Ru–AC anode, whereas the values obtained from others reached 45.2–149.6 mV. Interaction models were introduced to quantify the relationship between power generation and pollutant degradation. The conversion of highly toxic chlorophenols to organic acids could be accelerated by boosting the mass and electron transfer, thereby simultaneously enhancing CBs removal and power generation. This work provided important insights into pollutant-powered MFC development.

Efficacy and safety of TAVR versus SAVR in patients with small aortic annuli: A systematic review and meta-analysis

IntroductionPatients with a small aortic annulus (SAA) undergoing aortic valve replacement are at increased risk of patient-prosthesis mismatch (PPM), which adversely affects outcomes. Transcatheter aortic valve replacement (TAVR) has shown promise in mitigating PPM compared to surgical aortic valve replacement (SAVR). MethodsWe conducted a systematic review and meta-analysis following PRISMA guidelines to compare clinical outcomes, mortality, and PPM between SAA patients undergoing TAVR and SAVR. Eligible studies were identified through comprehensive literature searches and assessed for quality and relevance. ResultsNine studies with a total of 2476 patients were included. There was no significant difference in 30-day Mortality between TAVR vs SAVR groups (OR = 0.65, 95% CI [ 0.09–4.61], P = 0.22). There was no difference between both groups regarding myocardial infarction at 30 days (OR = 0.63, 95% CI [0.1–3.89], P = 0.62). TAVR was associated with a significantly lower 30-day major bleeding and 2-year major bleeding, Pooled studies were homogeneous (OR = 0.44, 95% CI [0.31–0.64], P < 0.01, I2 = 0, P = 0.89), (OR = 0.4 ,95% CI [0.21–0.77], P = 0.03, I2 = 0%, P = 0.62) respectively. TAVR was associated with a lower rate of moderate PPM (OR = 0.6, 95% CI [ 0.44–0.84], p value = 0.01, i2 = 0%, p value = 0.44). The overall effect estimate did not favor any of the two groups regarding short-term Mild AR (OR = 5.44, 95% CI [1.02–28.91], P = 0.05) and Moderate/severe AR (OR = 4.08, 95% CI [ 0.79–21.02], P = 0.08, I2 = 0%, P = 0.59). ConclusionOur findings suggest that both TAVR and SAVR are viable options for treating AS in patients with a small aortic annulus. TAVR offers advantages in reducing PPM and major bleeding, while SAVR performs better in terms of pacemaker implantation. Future studies should focus on comparing newer generation TAVR techniques and devices with SAVR. Consideration of patient characteristics is crucial in selecting the optimal treatment approach for AS.

Buried annealed proton-exchanged waveguide in periodically-poled MgO:LiTaO3 fabricated by surface-activated bonding for high-power wavelength conversion

Watt-class UV laser lights with symmetric spatial modes are suitable for high-resolution industrial applications. Channel waveguides with a guided mode of several ten microns diameter in MgO:LiTaO3 enhance integration capability while avoiding photorefractive damages during high-power wavelength conversion. We focused on buried waveguides fabricated by proton exchange, surface-activated bonding (SAB), and proton diffusion processes in periodically-poled (PP) MgO:LiTaO3. In this work, the mode profiles were simulated using the proton diffusion coefficients estimated by secondary ion mass spectrometry. Using the simulation results, the buried waveguides with a mode diameter larger than 30 μm were fabricated. By adopting designed PP structures, second harmonic generation (SHG) devices at a wavelength of 532 nm were fabricated. The nonlinear coupling coefficient was estimated to be 0.15 W−1/2 cm−1. Compared to the conventional annealed proton-exchanged waveguide SHG device without SAB, symmetric guided modes were obtained while maintaining the nonlinear coupling coefficient.

Comprehensive comparison and applicable range of separating and coupling numerical models of thermoelectric generation device for waste heat recovery

There are two different numerical modelling approaches of thermoelectric generation (TEG) device: separating model that is one-way coupling from CFD model to thermal-electric model and coupling model that is two-way coupling between CFD model and thermal-electric model. With the change of application conditions, the TEG device is subjected extensive changes of fluid parameters. To determine the applicable fluid range of sharing two models of TEG device, a comprehensive comparison between two models is conducted in this study. The results indicated that for the coupling numerical model, the Peltier heat has a negative effect on the temperature difference and output performance of thermoelectric module compared with the prediction results of separating numerical model. Therefore, an output error is induced between the prediction results of separating and coupling numerical models. This error can be decreased by increasing fluid mass flow rate and decreasing fluid temperature. Consequently, the applicable fluid ranges of sharing two models are divided by setting the different error bounds. It is suggested that the separating numerical model is given priority to reduce the calculation complexity when the fluid range of practical application is within a small error bound.

Numerical investigation of the hydrodynamic properties of oscillating water column air chambers

Abstract The oceans occupy nearly 71% of the Earth’s surface area. The ocean is rich in energy, and wave energy is one of its important components. Therefore, the study of wave energy generation devices is an important issue. In this paper, we analyze the effect of the size of the air chamber structure on the OWC (oscillating water column) wave energy conversion device under the action of unidirectional regular waves. To analyze the performance of the OWC device under real sea conditions, the wave climate at Sanmenxia is used as the experimental parameter. The performance and characteristic response with the variation of incident wave height, air chamber width and front wall thickness, are analyzed. The results show that the incident wave height, air chamber width, and front wall draft have significant effects on the performance of OWC. With the increase of incident wave height, the wave nonlinear effect increases. As the air chamber width decreases, the horizontal surface inside the air chamber undulates smoothly and the standing wave phenomenon disappears.

Cardiac Reverse Remodeling Mediated by HeartMate 3 Left Ventricular Assist Device: Comparison to Older Generation Devices.

Currently, the fully magnetically levitated left ventricular assist device (LVAD) HeartMate 3 (HM3) is the only commercially available device for advanced heart failure (HF) patients. However, the left ventricular (LV) functional and structural changes following mechanical unloading and circulatory support (MCS) with the HM3 have not been investigated. We compared the reverse remodeling induced by the HM3 to older generation continuous-flow LVADs. Chronic HF patients (n = 405) undergoing MCS with HeartWare Ventricular Assist Device (HVAD, n = 115), HM3 (n = 186), and HeartMate II (HM2, n = 104) at four programs were included. Echocardiograms were obtained preimplant and at 1, 3, 6, and 12 months following LVAD implantation. There were no differences in the postimplant serial LV ejection fraction (LVEF) between the devices. The postimplant LV internal diastolic diameter (LVIDd) was significantly lower for HM2 at 3 and 6 months compared with HVAD and HM3. The proportion of patients achieving "cardiac reverse remodeling responder" status (defined as LVEF improvement to ≥40% and LVIDD ≤5.9 cm) was 11.9%, and was similar between devices. HeartMate 3 appears to result in similar cardiac reverse remodeling as older generation CF-LVADs, suggesting that the fully magnetically levitated device technology could provide an effective platform to further study and promote cardiac reverse remodeling.

КОМУТУЮЧА НАПРУГА ТРИФАЗНОГО ДВОМОСТОВОГО КОМПЕНСАЦІЙНОГО ПЕРЕТВОРЮВАЧА

The results of a study of electromagnetic processes in a three-phase two-bridge compensation converter, which is one of the options for the circuit implementation of new generation compensation converters, are presented. The commutating link of the converter contains a three-phase capacitor battery and a three-phase group of fully controlled devices. This technical solution makes it possible to make the process of recharging capacitors controllable. Moreover, it becomes possible to change not only the magnitude of the capacitor voltage, but also its shape. It was noted that in the previous generation of compensation converters there was no ability to change the shape of the commutating voltage. The latter is a significant advantage of new generation devices, since it allows for high energy characteristics of the converter. This is confirmed by the results of a study of the energy capabilities of the converter under study in nine operating modes presented in the publication and the conclusion on the most effective modes. References 9, figures 10.

Biomimic Design of Solar Steam Generation Devices Enabled by the Tannin-Iron Complex.

Solar-powered steam generation equipment has experienced considerable advancement in recent years as it offers a cleaner and greener method for freshwater production. However, the devices always suffer from a complicated process, high cost, and salt accumulation, which hinder their further application. Here, inspired by the water lily, a highly efficient and antisalt accumulation interfacial solar-driven steam generation device was designed by using the tannic acid-Fe3+ complex as photothermal material. The designed evaporator could be quickly unfolded within 24 s after being irradiated with light and then produce fresh water. It folded within 10 s and then sank into water for removing the accumulated salt after removing the irradiation sources. In addition, the tannic acid-Fe3+ complex on the evaporator surface and the angle of the evaporator allowed light to be reflected several times within the evaporator, effectively increasing the solar energy conversion efficient (2.22 kg/(m2·h)), and apparently, the overall evaporation efficiency of 139.18% was achieved under 1 sun illumination. Moreover, it exhibited an extraordinary antisalt accumulation capacity (by working continuously for 7 days in 10 wt % saline water and 80% reduction in salt accumulation) as well as a low price ($ 1.11/m2). This design would provide a strategy to prepare an antisalt accumulation solar steam devices.

Reversible photo-electrochemical device for solar hydrogen and power generation

Reversible photo-electrochemical device for solar hydrogen and power generation

NURSING COUNSELING FOR THE OPTIMIZATION OF THE REMOTE MANAGEMENT OF PATIENTS WITH ILR AFTER CRYPTOGENIC STROKE

Abstract Background ILR is a device used to diagnose and document cardiac rhythm disorders in various clinical contexts including syncope and CS. The ILRs can be remotely monitored through a dedicated system consisting of a fully automatic home monitor or, in the latest generation devices, throughan APP that can be downloaded by the patient on his mobile phone. ILR remote monitoring can be performed by the nurse after acquiring the necessary skills on system functioning and knowledge about heart rhythm disorders. Methods Since 2017, a collaboration between Cardiologists and Neurologists has been established at our hospital providing a shared protocol for the management of patients with CS implanted with an ILR to detect asymptomatic AF. All CS patients referred for ILR implantation at our center received a MEDTRONIC ILR and were equipped with a remote monitoring system. ILR management protocol includes a first phase after the implant, where the nurse carries out patient training and counseling; enters all data in the Medtronic Carelink website, provides the patient with the home monitor, clearly explaining its use at home and, finally, obtains patient informed. Second phase of the protocol includes patient FU management, where the nurse reviews all remote transmissions, identifies any arrhythmic events and contacts by phone the patient to evaluate symptoms and, in case,establish the date for FU. Results Since 2017, 70 pz with CS (mean age:65±9 years,67.24% with CHADS2–VASc Score &amp;gt;=4) underwent ILR implantation.ILR remote monitoring allowed the diagnosis of AF in 27% pz (asymptomatic in 72%), of bradyarrhythmia in 4% and VT in 2%. Patients with arrhythmic diagnoses were contacted for FU in H to set up appropriate intervention. In described care pathway, the training and counselling carried out by nurses after the implant was crucial to establish the relationship of trust between patient and nurse, which significantly improved patient compliance. Conclusions The use of ILR has allowed to detect arrhythmias, even when asymptomatic, in patients affected by CS. In our experience, remote monitoring managed by trained nurses was crucial for the early diagnosis of AF. However, since technology is rapidly evolving, training updates to nurse staff regarding remote monitoring systems are essential to improve the counselling. Teamwork and constant cardiologist–nurse communication proved to be fundamental in offering the best care to these patients.

Impact of bottom-blowing parameters on melt pool homogenization in a 120-ton converter based on carbon-oxygen reaction

This paper studies a 120 t converter, focusing on the influence of the CO bubbles generated by the carbon-oxygen reaction during the decarburization process on the stirring action of the melt pool. It examines the effect of the intensity and arrangement of bottom blowing on the homogenization effect, taking into account the dynamics of CO bubbles generated from the carbon-oxygen reaction. Initially, a macroscopic kinetics model for the generation of CO bubbles during the carbon-oxygen reaction in converter steelmaking is established. Subsequently, a water model simulation device for CO bubble generation from the converter's carbon–oxygen reaction is designed, establishing a 120 t converter water model experimental setup with a similarity ratio of 1:8. The main indicator for evaluating the homogenizing effect of the converter is the mixing time, based on which, experimental schemes are designed. Water model experiments are conducted to study the influence of bottom-blowing flow and nozzle arrangement on the melt pool's stirring flow field under the action of carbon-oxygen reaction. The results show that greater generation intensity of CO bubbles from the carbon-oxygen reaction leads to shorter mixing time in the melt pool; when the angular spread of the bottom-blowing elements is small, the bottom-blowing gas flow is relatively concentrated, facilitating stirring in the melt pool. However, increasing the angular spread of the nozzles to a certain extent leads to the dispersion of bottom-blowing energy, making it difficult to form effective stirring; when the bottom-blowing flow is less than 1.5 Nm3/h, the mixing time of the melt pool decreases with the increase of bottom-blowing flow; when the bottom-blowing flow is greater than 1.5 Nm3/h, the mixing time of the melt pool increases with the increase of bottom-blowing flow. In addition, a series of industrial experiments were carried out, and the research results were applied to the actual production process. By comparing the test results after the optimization scheme with the production data of the original process, it was found that the optimization scheme significantly improved the smelting efficiency and reduced the production cost. These research results not only provide a theoretical basis, but also provide practical guidance for the optimization of converter smelting process.

A pareto strategy based on multi-objective optimal integration of distributed generation and compensation devices regarding weather and load fluctuations

In this study, we present a comprehensive optimization framework employing the Multi-Objective Multi-Verse Optimization (MOMVO) algorithm for the optimal integration of Distributed Generations (DGs) and Capacitor Banks (CBs) into electrical distribution networks. Designed with the dual objectives of minimizing energy losses and voltage deviations, this framework significantly enhances the operational efficiency and reliability of the network. Rigorous simulations on the standard IEEE 33-bus and IEEE 69-bus test systems underscore the effectiveness of the MOMVO algorithm, demonstrating up to a 47% reduction in energy losses and up to a 55% improvement in voltage stability. Comparative analysis highlights MOMVO's superiority in terms of convergence speed and solution quality over leading algorithms such as the Multi-Objective Jellyfish Search (MOJS), Multi-Objective Flower Pollination Algorithm (MOFPA), and Multi-Objective Lichtenberg Algorithm (MOLA). The efficacy of the study is particularly evident in the identification of the best compromise solutions using MOMVO. For the IEEE 33 network, the application of MOMVO led to a significant 47.58% reduction in daily energy loss and enhanced voltage profile stability from 0.89 to 0.94 pu. Additionally, it realized a 36.97% decrease in the annual cost of energy losses, highlighting substantial economic benefits. For the larger IEEE 69 network, MOMVO achieved a remarkable 50.15% reduction in energy loss and improved voltage profiles from 0.89 to 0.93 pu, accompanied by a 47.59% reduction in the annual cost of energy losses. These results not only confirm the robustness of the MOMVO algorithm in optimizing technical and economic efficiencies but also underline the potential of advanced optimization techniques in facilitating the sustainable integration of renewable energy resources into existing power infrastructures. This research significantly contributes to the field of electrical distribution network optimization, paving the way for future advancements in renewable energy integration and optimization techniques for enhanced system efficiency, reliability, and sustainability.

Compressed-SDR to HDR Video Reconstruction.

The new generation of organic light emitting diode display is designed to enable the high dynamic range (HDR), going beyond the standard dynamic range (SDR) supported by the traditional display devices. However, a large quantity of videos are still of SDR format. Further, most pre-existing videos are compressed at varying degrees for minimizing the storage and traffic flow demands. To enable movie-going experience on new generation devices, converting the compressed SDR videos to the HDR format (i.e., compressed-SDR to HDR conversion) is in great demands. The key challenge with this new problem is how to solve the intrinsic many-to-many mapping issue. However, without constraining the solution space or simply imitating the inverse camera imaging pipeline in stages, existing SDR-to-HDR methods can not formulate the HDR video generation process explicitly. Besides, they ignore the fact that videos are often compressed. To address these challenges, in this work we propose a novel imaging knowledge-inspired parallel networks (termed as KPNet) for compressed-SDR to HDR (CSDR-to-HDR) video reconstruction. KPNet has two key designs: Knowledge-Inspired Block (KIB) and Information Fusion Module (IFM). Concretely, mathematically formulated using some priors with compressed videos, our conversion from a CSDR-to-HDR video reconstruction is conceptually divided into four synergistic parts: reducing compression artifacts, recovering missing details, adjusting imaging parameters, and reducing image noise. We approximate this process by a compact KIB. To capture richer details, we learn HDR representations with a set of KIBs connected in parallel and fused with the IFM. Extensive evaluations show that our KPNet achieves superior performance over the state-of-the-art methods.

Study on the influence of ship waves on the dynamic response of floating tidal current power generation device

To study the influence of ship traveling waves on the hydrodynamic performance between the carrier platform and the turbine, the computational fluid dynamics method and the DFBI motion module of STAR CCM+ software were adopted. Under the condition of the coupling of the ship traveling wave and wave current generated at different speeds, the overall motion response of the power plant is simulated. What’s more, the influence of different wave conditions on the heave, pitch, and roll of the carrier platform and the energy efficiency of the turbine is analyzed. The results show that the ship speed has little effect on the carrier heave motion, but the maximum value of the carrier pitch motion increases with the increase in the ship speed. The value of turbine energy acquisition efficiency always decreases with decreasing lateral spacing and increases with decreasing speed. This paper has a certain reference value for the engineering application of floating tidal current power generation equipment.

Optimizing energy harvesting from ship-based buoys using Bat Algorithm—A case study

It is imperative to explore alternative, preferably renewable energy sources to diminish our reliance on coal and oil, thereby mitigating the adverse impacts of greenhouse gases. For this, an approach was proposed to generate electrical power through energy harvesting from a ship’s buoy riding a lake’s wave. Specifically, an electrical power generation device was established on the side of the ship using a generator and a rod connected to the skirt-type buoy. With the buoy bobbing in the waves, the rod swung due to the relative height difference between the bobbing buoy and the ship, thus generating periodic electrical power. A case study was performed with a fetch of 4 km, a lake depth of 10 m, and a wind speed of 4.5 m/s. To maximize the electrical power generated, the ship-based energy harvester was optimized using a bat algorithm. The resulting mathematical analysis exhibits a worthy electrical power output of 241.6 W. This study underscores the potential of hydraulic energy generation as a promising and sustainable renewable energy and offers valuable insights into optimizing energy harvesters for maximized electricity production.

Effect of internal flow of Venturi-type power generation device on piston movement

ABSTRACT In the development and utilisation of hydraulic resources, high head and low flow hydraulic resources have not been fully utilised. To develop hydronic resources with low flow at high heads, this work designs a Venturi-type power generation device and studies the internal flow of the device by combining experiments and numerical simulations. The results indicate that the diameter ratio of the leading and branch pipes in the device significantly impacts pressure loss, and the diameter ratio at the throat is close, resulting in a significant pressure loss and an impact on the internal flow of the primary pipe. When the flow rate ratio of the leading and branch pipes is more than 4.03%, the piston can complete the reciprocating stroke, and the completion time decreases with the flow rate increase. When the flow rate ratio of the primary and branch pipes reaches 5.27%, the completion time approaches its limit. When the flow rate of the Venturi primary pipe is greater than 30 m3/h, the device begins to experience local cavitation, and noticeable noise appears at the diffusion tube.

Photovoltaic cooling and atmospheric water harvesting using a hygroscopic hydrogel

Photovoltaic power generation technology has gained significant attention from researchers due to its advantages of simple structure, environmental friendliness, and high sustainability. However, the photon-to-electron conversion efficiency (PCE) of photovoltaic (PV) panels is limited by the residual heat produced during the solar absorption process. Thus, an effective heat management is vital for the long-term stable and efficient photovoltaic system. In this paper, a novel dual-function device was proposed to realize effective cooling of PV panels and harvest freshwater from the air simultaneously. Through the utilization of evaporative cooling with hygroscopic hydrogel, the photovoltaic cooling-water generator (PVC-WG) device achieves up to 8 °C reduction in the operating temperature of PV panels along with a freshwater generation rate of 122.32 g m−2 h−1 in the laboratory at solar intensity of 1 kW m−2. At night, the hygroscopic hydrogel automatically absorbed moisture from the air to achieve self-regeneration, confirming its excellent reusability. Even in real outdoor environments, a maximum cooling effect of 9.2 °C and a stable freshwater generation of 98.08 g m−2 day−1 could be achieved. The system not only accomplishes thermal management for PV panels but also attains additional freshwater generation, which enhances the efficiency of harnessing the entire spectrum of solar energy.

Stencil-Printed Scalable Radial Thermoelectric Device Using Sustainable Manufacturing Methods

In this study, we used n-chitosan-Bi2Te2.7Se0.3 and p-chitosan-Bi0.5Sb1.5Te3 composite inks to print a circular thermoelectric generator (TEG) device using a low-energy-input curing method. Thermoelectric (TE) composite films were fabricated using varying sizes of thermoelectric particles and a small chitosan binder (0.05 wt. %). The particles and binder were hot pressed at an applied pressure of 200 MPa and cured at 200 °C for 30 min. We achieved ZT of 0.35 for the n-type and 0.7 for the p-type TE composite films measured at room temperature. A radial TEG was fabricated using the best-performing n-type and p-type composite inks and achieved a power output of 87 µW and a power density of 727 µW/cm2 at a temperature difference of 35 K; these are among the best-reported values for printed TEG devices. Using a low-energy-input fabrication method, we eliminated the need for high-temperature and long-duration curing processes to fabricate printing devices. Thus, we envisage that the low-energy-input curing process and cost-effective printable strategy presented in this work pave the way for sustainable manufacturing of large-scale energy harvesting TEG devices.

Research on Maximum Power Control of Direct-Drive Wave Power Generation Device Based on BP Neural Network PID Method

Ocean wave energy is a new type of clean energy. To improve the power generation and wave energy conversion efficiency of the direct-drive wave power generation system, by addressing the issue of large output errors and poor system stability commonly associated with the currently used PID (proportional, integral, and derivative) control methods, this paper proposes a maximum power control method based on BP (back propagation) neural network PID control. Combined with Kalman filtering, this method not only achieves maximum power tracking but also reduces output ripple and tracking error, thereby enhancing the system’s control quality. This study uses a permanent magnet linear generator as the power generation device, establishes a system dynamics model, and predicts the main frequency of irregular waves through the Fast Fourier Transform method. It designs a desired current tracking curve that meets the maximum power strategy. On this basis, a comparative analysis of the control accuracy and stability of three control methods is conducted. The simulation results show that the BP neural network PID control method improves power generation and exhibits better accuracy and stability.