Low Power Levels Research Articles

Design and Development of a Laser Warning Sensor Prototype for Airborne Application


 
 
 Due to recent developments in high-energy laser systems, the laser is becoming one of the most potential choices in battlefield applications. Laser of a laser range finder used to find target distance may be of nanosecond pulse width and a single pulse may be sufficient to gather the instantaneous range information. A laser target designator is a similar laser with higher energy and with programmable pulse repetition frequencies5,7. Detection of such a specific battlefield laser radiation along with recognizing friend or foe is required for countermeasures. Designing a laser detection system that is capable of detecting such low-power level laser pulses of nanosecond pulse width at a long distance is a critical design and a challenging task. Again detecting a wide wavelength band that can start from 500 nm to around 1700 nm range using a single detector or device is also a challenging task. In this work, a sensor system is being designed and a prototype is developed to cover such a long band detection using a single detector for high-energy lasers. Also, in addition to detecting hostile code, the direction of an incoming laser beam is tried to incorporate into this sensor. The sensor can be utilized to detect unknown or non-friendly laser illumination from within a specific angular cone and distance.
 
 

A Compact-Size Multiple-Band Planar Inverted L-C Implantable Antenna Used for Biomedical Applications.

In this paper, a compact-size multiple-band planar inverted L-C implantable antenna is proposed. The compact antenna has a size of 20 mm × 12 mm × 2.2 mm and consists of planar inverted C-shaped and L-shaped radiating patches. The designed antenna is employed on the RO3010 substrate (εr = 10.2, tanδ = 0.0023, and thickness = 2 mm). An alumina layer with a thickness of 0.177 mm (εr = 9.4 and tanδ = 0.006) is used as the superstrate. The designed antenna operates at triple-frequency bands with a return loss of -46 dB at 402.5 MHz, -33.55 dB at 2.45 GHz, and -41.4 dB at 2.95 GHz, and provides a size reduction of 51% compared with the conventional dual-band planar inverted F-L implant antenna designed in our previous study. In addition, the SAR values are within the safety limits with a maximum allowable input power (8.43 mW (1 g) and 47.5 mW (10 g) at 402.5 MHz; 12.85 mW (1 g) and 47.8 mW (10 g) at 2.45 GHz; and 11 mW (1 g) and 50.5 mW (10 g) at 2.95 GHz). The proposed antenna operates at low power levels and supports an energy-efficient solution. The simulated gain values are -29.7 dB, -3.1 dB, and -7.3 dB, respectively. The suggested antenna is fabricated and the return loss is measured. Our findings are then compared with the simulated results.

Roles and Functions of Uncle Ho Soldiers in Official Communication Topics

The main established relationship/communication role of Uncle Ho's soldiers in the collective is mainly a powerful role. The friendly role appears but is only expressed in the CS peer pair in the context of formal communication with low legality, with 3 novels, 8 short - medium stories, 5 memoirs to conduct a survey, classifying and analyzing communication topics in the official communication of Uncle Ho soldiers on the following aspects: communication topics of upper and lower roles; communication topics of horizontal (peer) pairs. The results show that: The pair of soldier-soldier roles (CS - CS) is a pair of roles reflecting the relationship between soldiers and soldiers based on the background of responsibility and duty. These are roles that have a low level of power and the potential to transition into a friendly role. This is one of the other unique characteristics of Uncle Ho's soldier.

Optomechanical Cooling and Inertial Sensing at Low Frequencies

An inertial sensor design is proposed in this paper to achieve high sensitivity and large dynamic range in the subhertz-frequency regime. High acceleration sensitivity is obtained by combining optical cavity readout systems with monolithically fabricated mechanical resonators. A high-sensitivity heterodyne interferometer simultaneously monitors the test mass with an extensive dynamic range for low-stiffness resonators. The bandwidth is tuned by optical feedback cooling to the test mass via radiation pressure interaction using an intensity-modulated laser. The transfer gain of the feedback system is analyzed to optimize system parameters towards the minimum cooling temperature that can be achieved. To practically implement the inertial sensor, we propose a dynamic cooling mechanism to improve cooling efficiency while operating at low optical power levels. The overall system layout presents an integrated design that is compact and lightweight.

PO-03-064 BASELINE LOCAL IMPEDANCE AND CHANGES IN LOCAL IMPEDANCE ARE PREDICTORS OF ELECTRODE TISSUE COUPLING IN RF-ABLATION

Radiofrequency (RF) current remains the most used ablation technology in the EP lab. Durable lesion formation without collateral tissue damage is key for obtaining efficient and safe procedures. RF power, duration and contact force (CF) are considered as main determinants of lesion size. Recently published data show that electrode tissue coupling (ETC) is another important parameter of lesion formation. This ex vivo model was created to investigate local impedance (LI) changes and lesion size when alternating ETC-levels. RF-lesions were created using a CF and LI sensing catheter in an ex vivo porcine cardiac model. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and contact force. RF power of 20W, 30W, 40W, and 50W was used. The ETC levels were systematically varied between minor and full coupling. In minor ETC-level, only the distal end of the catheter is in contact with the tissue. In full ETC-level, the whole catheter tip is in contact with the tissue. All parameters (power, temperature, global and local impedance, CF, ETC, lesion size) were measured constantly during RF-application, enabling real-time correlation of all parameters and lesion size. 8654 measurements of lesion depth and diameter were analyzed after creating 72 lesions. Lesion depth and diameter in full ETC-level were significantly higher compared to minor ETC-level (s. Table 1). Interestingly, lesions in lower power levels (20-30 Watt), but full ETC-level became wider and deeper than lesions in high power levels (40-50 Watts), but minor ETC-level (s. Figure 1). These observations were made despite shorter RF-duration (54.00 ± 13.07 s vs. 47.11 ± 17.57 s, p=0.032) in lesions with full ETC-level due to higher incidence of steam pops (14 vs. 6 steam pops, p = 0.032). Baseline LI and LI-drop were significantly higher in full ETC-level (Figure 1), but no relevant difference was observed in baseline GI. Baseline LI and LI changes during ablation provide information about ETC-levels and interaction of the RF ablation catheter with cardiac tissue. ETC-levels, as predicted by LI, had a significantly higher impact on RF lesion size than RF power or RF-duration. Therefore, LI should be monitored during RF ablation for estimating ETC-levels and lesion formation.Tabled 1Table 1. Lesion size and impedance changes in different ETC-levels.Minor ETC (n=36)Full ETC (n=36)p-valueMaximum diameter [mm]8.48 ± 1.6110.54 ± 1.63<0.001Maximum depth [mm]5.13 ± 0.999.45 ± 1.45<0.001Start LI [Ω]236.89 ± 26.42300.67 ± 21.61<0.001Start GI [Ω]150.61 ± 21.61151.33 ± 23.680.893LI-drop [Ω]-53.61-125.53<0.001GI-drop [Ω]-21.33-33.44<0.001 Open table in a new tab

Physics design, fabrication, RF measurement and beam commissioning of a dual beam drift tube linac

A novel type dual-beam drift tube linac (DB-DTL) prototype was firstly designed to prove the feasibility of the multi-beam type DTL at the institute of modern physics. The physics design, cavity fabrication, low-power RF measurement, RF conditioning and beam commissioning of the DB-DTL cavity were completed and presented in this paper. Operating at 81.25 MHz, the DB-DTL was designed to accelerate 10 mA proton from 0.56 MeV to 2.5 MeV. The field distribution of the DB-DTL cavity were measured at low RF power level and particle tracing using measured field were done, which both agree well with the physics design. The measured Q 0 value and the shunt impedance are 11606 and 172 MΩ/m, respectively. The RF conditioning and the first beam commissioning of the DB-DTL cavity were completed. The beam experiment platform was built at the Lanzhou university due to the academy research cooperation between the institute of modern physics, Sun Yat-sen university and Lanzhou university. Based on the existing experiment condition, 2.5 MeV proton acceleration and measurement were successfully achieved at 42 kW (0.85*Q 0)) RF power of the DB-DTL cavity, which match the physics design very well.

Factors affecting the temperature variation rate of bamboo during high-frequency heating

High-frequency electromagnetic fields refer to electromagnetic waves with frequencies ranging from 100 kHz to 300 MHz. High-frequency medium heating has the advantages of uniform heating, rapid energy consumption, and environmental protection. While it has a wide range of applications, the use of high-frequency dielectric heating in the bamboo industry is rare. Understanding the influence of bamboo temperature rise rate in high-frequency heating could promote bamboo industry development. In this work, curved bamboo was tested with high-temperature energy for continuous heating. The influence of moisture content of bamboo, sample thickness, and high-frequency processing power on temperature rise rate were studied. The results showed that the water content of bamboo affected the temperature rise rate. The effect of high-frequency heating was highest when the moisture content of bamboo was close to 11%. The thickness of sample had little effect on the temperature rise rate, but the high-frequency power had a significant effect on the temperature rise rate. The temperature rise rate of the lower and higher frequency power levels increased slowly and was close to constant. The heating power was 11 kW, and the temperature rise rate was the highest.

Design and Analysis of Response Threshold of Energy Selective Surface Based on Diode Girds

This article presents a detailed analysis of the response threshold of energy selective surface (ESS) based on semiconductors. ESS could adaptively protect electronic equipment from high-power microwave (HPM) when the field intensity of incident waves surpasses the response threshold, at which the semiconductors loaded on ESS are triggered on by the induced voltages or currents. The effects of various design parameters and the implied physical mechanism are investigated using electromagnetic simulations and experiments. With the help of the equivalent-circuit model (ECM), methods of modulating response threshold are proposed. According to our research, the response threshold of ESS is closely related to the quality factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q_{p}$</tex-math></inline-formula> of the corresponding ECM. ESS with a larger <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q_{p}$</tex-math></inline-formula> is supposed to be triggered on at a lower power level. The proposed method is used to design ESS with different response thresholds through adjustment of geometry parameters instead of replacing semiconductors. Prototypes are fabricated and measured under different power levels. The results agree well with simulations, proving the proposed method is effective and useful in the design of ESS.

Wideband Power-Dependent Power Limiter Based on Distributed Low-Temperature Superconductor rf-SQUIDs for Cryogenic RF Receivers

A novel design of a radio-frequency (RF) power limiter for protecting sensitive superconductor receiver components from high-power microwave signals is presented. In this approach, two low- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T} _{c}$ </tex-math></inline-formula> superconductor microstrip lines, one of which is coupled with an array of RF superconducting quantum interference devices (rf-SQUIDs), are combined with a pair of hybrid couplers to provide the power limiting operation at very low RF power levels. The key concept is built on the fact that a microstrip line coupled to an array of rf-SQUIDs behaves as a power-dependent phase shifter and its phase can be controlled by the input RF power. This phenomenon is exploited to achieve the desired RF power-limiting operation. The device is fabricated using an eight-layer niobium-based superconducting process node SFQ5ee by MIT Lincoln Laboratory (MIT-LL). A monolithically integrated wideband hybrid coupler is used in this design as it dictates the bandwidth of the overall device. The operating frequency of the power limiter is 10 GHz with a 2-GHz bandwidth. The performance of the device is measured for input RF power levels ranging from −30 to +10 dBm, as well as arising intermodulation products are experimentally investigated. The output power increases linearly with the input power up to −15 dBm, and for higher power levels, the device offers an increasing attenuation to limit the output RF power starting above −15 dBm.

Psycho-neuro-biological Correlates of Beta Activity

Chronic stress and anxiety in everyday life can lead to sympathetic hyperactivity. This can be observed as behavioral, chemical, and neurological changes, including increased rumination, anxiety, and depression, and chemical changes in biological markers like homocysteine. In the EEG, increased beta (13–30 Hz) wave activity, especially high beta (&gt; 20 Hz) has long been noted in anxiety states. However, recent research indicates that low beta waves (13–20 Hz) may play a role as well. The current paper presents a pilot study that assessed the Neurocycle’s efficacy as a nonpharmacological mind-management therapy for people who struggle with anxiety and depression. We assessed psychometrics, blood-serum homocysteine levels, and quantitative electroencephalography (qEEG). Efficacy of the Neurocycle was demonstrated by improved psychometric self-assessment over the study. We observed a positive correlation between subject’s low beta relative power and homocysteine levels. The findings validate the Neurocycle’s efficacy for improving mental health as measured by behavioral, chemical, and neurological measures. Altogether, these findings support low beta’s role in stress/anxiety manifestation given that its modulation significantly correlated with stress biomarkers in patients’ blood samples and stress and anxiety self-assessments. Future work should expand these findings with larger datasets to confirm the ranges of healthy and maladaptive low beta.

Stabilization of Olive Oil in Water Emulsion with Dairy Ingredients by Pulsed and Continuous High Intensity Ultrasound.

Application of high intensity ultrasound (HIUS) for stabilization of olive oil in water emulsion with different dairy ingredients including sodium caseinate (NaCS) and whey protein isolate (WPI) was investigated. The emulsions were prepared by homogenization with a probe and then treated with either a second homogenization or HIUS at a different power level (20 and 50%) in pulsed or continuous mode for 2 min. The emulsion activity index (EAI), creaming index (CI), specific surface area (SSA), rheological properties, and droplet size of the samples were determined. The temperature of the sample rose when HIUS was applied in continuous mode and at increasing power level. HIUS treatment increased EAI and SSA of the emulsion and decreased droplet size and CI compared with those of the double-homogenized sample. Among the HIUS treatments, the highest EAI was found in the emulsion with NaCS that was treated at a power level of 50% in continuous mode, and the lowest one was obtained by HIUS applied at a power level of 20% in pulsed mode. SSA, droplet size, and span of the emulsion were not affected by HIUS parameters. Rheological properties of HIUS-treated emulsions were not different from those of the double-homogenized control sample. Continuous HIUS at 20% power level and pulsed HIUS at 50% power level reduced creaming in the emulsion after storage at a similar level. HIUS at a low power level or in pulsed mode can be preferred for heat sensitive materials.

Development and Experimental Validation of a Reduced-Scale Single-Phase Modular Multilevel Converter Applied to a Railway Static Converter

With special emphasis in recent years, an increase has been verified not only in demand but also in the price of electricity, arising the need to develop more reliable and efficient electrical energy conversion systems. In this context, emerges the utilization of the modular multilevel converter (MMC) based on submodules. The key to the MMC is modularity, which allows the converter to reach higher performance levels, improving the voltage and current output signals of the converter, in a compact solution. The modularity concept allows the increase of the operation voltage using submodules in series, and the increase of the operating current using submodules in parallel. Additionally, in the event of a submodule malfunction, the converter can be reconfigured and continue the operation, albeit at a lower power level. Due to its versatility, the MMC can be used in a variety of applications, such as HVDC power transmission systems, solid-state transformers, renewable energy interfaces, and more recently, railway power systems. In this context, this paper focuses on the development and experimental validation of a single-phase MMC based on the use of half-bridge submodules applied to a railway static converter, where the main focus lies on the AC side control. The control algorithms are fully described for a single-phase MMC reduced-scale prototype implemented (500 W, 230 V–50 Hz, 200 VDC), connecting two submodules in series in the upper arm, two submodules also in series in the lower arm, the respective driver and command circuits, sensing and signal conditioning circuits, as well as a digital control platform recurring to the DSP TMS320F28379D. Experimental results were obtained to validate each submodule individually, and, later, to verify the operation of the MMC with the set of four submodules.

Conceptual Design of the Steam Generators for the EU DEMO WCLL Reactor

In the framework of the EUROfusion Horizon Europe Programme, ENEA and its linked third parties are in charge of the conceptual design of the steam generators belonging to EU DEMO WCLL Breeding Blanket Primary Heat Transfer Systems (BB PHTSs). In particular, in 2021, design activities and supporting numerical simulations were carried out in order to achieve a feasible and robust preliminary concept design of the Once Through Steam Generators (OTSGs), selected as reference technology for the DEMO Balance of Plant at the end of the Horizon 2020 Programme. The design of these components is very challenging. In fact, the steam generators have to deliver the thermal power removed from the two principal blanket subsystems, i.e., the First Wall (FW) and the Breeding Zone (BZ), to the Power Conversion System (PCS) for its conversion into electricity, operating under plasma pulsed regime and staying in dwell period at a very low power level (decay power). Consequently, the OTSG stability and control represent a key point for these systems’ operability and the success of a DEMO BoP configuration with direct coupling between the BB PHTS and the PCS. In this paper, the authors reported and critically discussed the FW and BZ steam generators’ thermal-hydraulic and mechanical design, the developed 3D CAD models, as well as the main results of the stability analyses and the control strategy to be adopted.

Harvesting microwave energy using pyroelectricity of nanostructured graphene/zirconium-doped hafnium oxide ferroelectric heterostructures

In this work, we present the design, atomistic/circuit/electromagnetic simulations, and the experimental results for graphene monolayer/zirconium-doped hafnium oxide (HfZrO) ultra-thin ferroelectric-based field effect transistors fabricated at the wafer scale, regarding the pyroelectricity generation directly from microwave signals, at room temperature and below it, namely at 218 K and at 100 K. The transistors work like energy harvesters, i.e. they collect low-power microwave energy and transform it into DC voltages with a maximum amplitude between 20 and 30 mV. The same devices function as microwave detectors in the band 1–10.4 GHz and at very low input power levels not exceeding 80 μW when they are biased by using a drain voltage, with average responsivity values in the range 200–400 mV mW−1.

A novel self‐adaptive rectifier with wide input range

A 2.45-GHz self-adaptive rectifier based on a two-way Gysel power divider (PD) with switch networks (SN), an impedance transform network (ITN), a feedback network (FN) and two rectifiers is developed in this paper. The SNs and ITN are controlled by FN according to output voltages. The rectifier is in single-path mode at a low power level and switches to two-path mode at a high power level. It has been simulated, fabricated and tested. The original input power range when efficiency is above 50% is from −3 to 11 dBm. After being connected to the PD, the input power range is expanded to −6 to 15 dBm, with a maximum efficiency of 71.1% at 1400 Ω. The proposed design only leverages one type of rectifier. The outputs are symmetric.

High Efficiency Bidirectional LLC+C Resonant Converter With Parallel Transformers for Solar-Charged Electric Vehicles

Recent interest in electric vehicles with onboard solar generation presents a new opportunity for using solar electric vehicles (SEVs) for distributed generation when the traction battery is fully charged. This concept presents a new power electronic challenge: the onboard charger should have high efficiency in the grid-to-vehicle (G2V) direction for normal charging power levels (i.e., 6.6 kW) and also high efficiency in the vehicle-to-grid (V2G) direction for much lower solar power levels (i.e., < 800 W). However, typical onboard charger topologies have low efficiency at light loads. This article proposes a novel bidirectional LLC+C converter to address this challenge. It operates as a full-bridge LLC converter in the G2V direction and a half-bridge LLCC converter with a smaller transformer in the V2G direction. Simulation results show a maximum efficiency gain of 5.1% in the V2G direction compared to the standard full-bridge LLC converter. To experimentally validate the topology and operation, a 6.6-kW prototype with 450–700-V input is designed, built, and tested. The experimental results show that the proposed converter achieves high efficiency in the V2G direction at 700 W (95.7%).

Vertical GeSn nanowire MOSFETs for CMOS beyond silicon

The continued downscaling of silicon CMOS technology presents challenges for achieving the required low power consumption. While high mobility channel materials hold promise for improved device performance at low power levels, a material system which enables both high mobility n-FETs and p-FETs, that is compatible with Si technology and can be readily integrated into existing fabrication lines is required. Here, we present high performance, vertical nanowire gate-all-around FETs based on the GeSn-material system grown on Si. While the p-FET transconductance is increased to 850 µS/µm by exploiting the small band gap of GeSn as source yielding high injection velocities, the mobility in n-FETs is increased 2.5-fold compared to a Ge reference device, by using GeSn as channel material. The potential of the material system for a future beyond Si CMOS logic and quantum computing applications is demonstrated via a GeSn inverter and steep switching at cryogenic temperatures, respectively.

Performance improvement of non-orthogonal multiple access with a 3D constellation and a 2D IFFT modulator.

In this paper, we propose a performance improvement of non-orthogonal multiple access (NOMA) with a three-dimensional (3D) constellation and a two-dimensional Inverse Fast Fourier Transform IFFT modulator (2D-IFFT) for the passive optical network (PON). Two kinds of 3D constellation mapping are designed for the generation of a three-dimensional NOMA (3D-NOMA) signal. Higher-order 3D modulation signals can be obtained by superimposing signals of different power levels by pair mapping. Successive interference cancellation (SIC) algorithm is implemented at the receiver to remove interference from different users. Compared with the traditional two-dimensional NOMA (2D-NOMA), the proposed 3D-NOMA can increase the minimum Euclidean distance (MED) of constellation points by 15.48%, which enhances the bit error rate (BER) performance of the NOMA. The peak-to-average power ratio (PAPR) of NOMA can be reduced by 2 dB. A 12.17 Gb/s 3D-NOMA transmission over 25 km single-mode fiber (SMF) is experimentally demonstrated. The results show that at the bit error rate (BER) of 3.8 × 10-3, the sensitivity gain of the high-power signals of the two proposed 3D-NOMA schemes is 0.7 dB and 1 dB compared with that of 2D-NOMA under the condition of the same rate. Low-power level signal also has 0.3 dB and 1 dB performance improvement. Compared with 3D orthogonal frequency-division multiplexing (3D-OFDM), the proposed 3D-NOMA scheme could potentially expand the number of users without obvious performance degradation. Due to its good performance, 3D-NOMA is a potential method for future optical access systems.

High Power Density Interleaved ZCS 80-kW Boost Converter for Automotive Applications

High system efficiency at all power levels is desired for electric vehicle (EV) propulsion systems. Conventional boost converters employed in EV traction architectures exhibit significantly lower efficiencies at low-power levels when operated under traditional fixed-frequency pulsewidth modulation (PWM) techniques. Also, low system power densities are associated with conventional boost converters due to their bulky inductors. These two shortcomings are addressed here through a comprehensive design methodology for an 80-kW interleaved boost converter stepping a low battery voltage up to an 800-V dc link. The designed converter employs a discontinuous conduction mode (DCM) variable-frequency control strategy to achieve an efficiency increase at low-power levels and, thus, a fairly constant efficiency throughout the entire drive schedule. A system loss model is developed to decompose analytically the loss mechanisms and, thus, determine the optimized design parameters for the variable-frequency control strategy and converter magnetics. Moreover, a custom inductor design based on distributed air gaps and aggressive thermal management through potting is integrated into the design methodology to further increase the converter power density. An 80-kW prototype is fabricated achieving a total power density of 55.6 kW/L, and experimentally tested, yielding system efficiencies above 96% for all power levels.

8.56-GHz quasi-optical launcher system with incident-mode selectivity on the QUEST spherical tokamak

An 8.56-GHz quasi-optical launcher system with incident-mode selectivity was developed for non-inductive electron cyclotron (EC) plasma ramp-up and long-pulse sustainment, and effective bulk-electron heating on the Q-shu University experiment with steady-state spherical tokamak (QUEST). A novel polarization-selective system was proposed to conduct fundamental and second harmonic EC heating and current drive experiments with ordinary and extra-ordinary mode waves, respectively. Selectivity of the incident modes or polarizations was confirmed using the whole developed system at a low power level. A large-sized mirror launcher was developed to inject the beam whose size was as small as possible near the QUEST major radius. The designed mirror performance was checked using a three-dimensional electromagnetic-wave simulator and a low-power test. Ultimately, 0.15-m sized beams for both the two polarizations were successfully attained near the QUEST major radius, even in low-frequency applications with long propagation.