A comprehensive aerodynamic-thermalmechanical design method for fast response turbocharger applied in aviation piston engines

Limited by the poor transient response performance of turbochargers,the dynamic performance of aviation piston engines tends to deteriorate.In a bid to enhance the turbocharger’s acceleration capabilities,this study scrutinizes various factors impacting its performance.Based on the operational principles and transient response process of the turbocharger,three types of in-ertiadnamely,aerodynamic inertia(ADI),thermal inertia(TI),and mechanical inertia(MI)d are identified and addressed for design.To begin,this paper pioneers the innovative definition of a method for evaluating the transient response performance of the turbocharger.This method incor-porates the introduction of an ADI parameter,inspired by the definition of MI.Subsequently,a thin-walled volute design with a low Biot number and a lightweight turbine impeller is introduced to reduce the turbocharger’s TI and MI.The simulation results of theflowfield distribution within the volute and diffuser demonstrate the comprehensive design method’s effectiveness in improving gas pressure and temperature distributions in these components.Notably,the pressure distributionfluctuation in the constant moment-of-momentum volute(CMV)is 62.8%lower than that in the constant velocity moment volute(CVMV).The low-TI thin-walled volute not only en-hances the turbocharger’s response speed but also reduces its weight by approximately 40%.The impact of three types of inertia on the engine’s response speed is quantified as follows:ADI(94%)>MI(5%)>TI(1%).This conclusion has been verified through test results of both the turbocharger and the engine.This design method not only significantly improves the turbo-charger’s response performance but also offers valuable insights for the optimal design of other blade mechanical systems.

Metal–organic framework wafer enabled fast response radiation detection with ultra-low dark current

Semiconductive metal–organic frameworks(MOFs)have attracted great interest for the electronic applications.However,dark currents of present hybrid organic–inorganic materials are 1000–10,000 times higher than those of commercial inorganic detectors,leading to poor charge transportation.Here,we demonstrate a ZIF-8(Zn(mim)_(2),mim=2-methylimidazolate)wafer with ultra-low dark current of 1.27 pA·mm^(-2) under high electric fields of 322 V·mm^(-1).The isostatic pressing preparation process provides ZIF-8 wafers with good transmittance.Besides,the presence of redox-active metals and small spatial separation between components promotes the charge hopping.The ZIF-8-based semiconductor detector shows promising X-ray detection sensitivity of 70.82μC·Gy^(-1)·cm^(-2) with low doses exposures,contributing to superior X-ray imaging capability with a relatively high spatial resolution of 1.2 lp·mm^(-1).Simultaneously,good peak discrimination with the energy resolution of~43.78%is disclosed when the detector is illuminated by uncollimated 241Am@5.48 MeVα-particles.These results provide a broad prospect of MOFs for future radiation detection applications.

Recent advances on organic-inorganic hybrid perovskite photodetectors with fast response

In the last decade,optoelectronic devices based on organic-inorganic hybrid perovskite(OIHP)materials,which have unique advantages of direct bandgap,large absorption coefficient,low density of defects,long charge carrier lifetime,diffusion length,and solution processability,have traveled with traditional inorganic semiconductor devices.The state-of-the-art OIHP photodetectors have contributed a comparable performance with Si and III-V compound semiconductor based photodetectors.Large amount of efforts have been focused on improving sensitivity,broadening detection spectra,enlarging linear dynamic range.However,few reports emphasized the important parameter of response speed.In this review,we summarize the progress and applications of OIHP photodetectors with fast response.Based on photovoltaic and photoconductive-type OIHP photodetectors,the working principle and key factors on determining response speed are systematically mentioned.Then,the research progress of response speed,which is composed of resistance-capacitance(RC)time constant and charge carrier transit time is discussed in detail.Subsequently,considering the intrinsic flexibility of perovskite materials,we briefly discuss the flexible photodetectors.Finally,an outlook and potential rules for designing fast-response OIHP photodetectors are further proposed.

Fast response speed of mechanically exfoliated MoS2 modified by PbS in detecting NO2

MoS2,acting as a promising gas sensing material,has shown huge potential in monitoring of toxic and harmful gases at room temperature.However,MoS2-based gas sensors still suffer from poor gas sensing performance such as poor sensitivity,long response time.Constructing the hete ro structure is an effective approach to improve gas-sensing performance of MoS2.Herein,PbS@MoS2 composites synthesized by mechanical exfoliation combining with wet-chemical precipitation are used to investigate its performance in detecting NO2 at room temperature.The response value of PbS@MoS2 gas sensor against NO2 is significantly improved compared with the pure MoS2 gas sensor.At the same time,the modification with PbS also accelerates the response speed of MoS2,and the response time is almost reduced by two orders of magnitude,from hundreds of seconds to less than ten seconds.The enhanced response value and fast response time are mainly benefited from the modulation effect of NO2 to PbS@MoS2 heterostructure and the mechanically exfoliated MoS2 surface with few defects.This work can be expected to provide useful guidance for designing composite materials with excellent gas sensing properties.

A Method for the Determination of Turbulence Intensity by Means of a Fast Response Pressure Probe and its Application in a LP Turbine

This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic pressure probe. The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put into the adjustment of all relevant model parameters. Blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, inlet turbulence intensity and Reynolds numbers were chosen to reproduce the full scale LP turbine. Measurements were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The total pressure random fluctuations are obtained by selectively filtering, in the frequency domain, the deterministic unsteadiness due to the rotor blades and coherent structures. The turbulence intensity is derived from the inverse Fourier transform and the correlations between total pressure and velocity fluctuations. The determination of the turbulence intensity allows the discussion of the interaction processes between the stator and rotor for engine-representative operating conditions of the turbine.

Fast response 2×2 thermo-optic switch with polymer/silica hybrid waveguide

A polymer/silica hybrid 2×2 multimode-interference switch is designed and fabricated. Instead of polymer Mach-Zehnder interferometer thermo-optic （TO） silica is used as under-cladding to accelerate heat release because of its large thermal conductivity. The developed switch exhibits low power consumption of 6.2 mW, low crosstalk of about 28 dB, and short response time. The rise and fall times of 103 and 91 its for this hybrid switch are shortened by 40.8% and 52.4%, respectively, compared with those of the fabricated TO switch （174 and 191 μs） using polymer as both upper- and under-claddings.

Decyloxyphenyl-substituted Quinoxaline-embedded Conjugated Electrochromic Polymers with High Switching Stability and Fast Response Speed

Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3- bis（4-decyloxyphenyl）-5,8-bis（3,4-dimethoxylthiophen-2-yl）quinoxaline] （P1） and poly[2,3-bis（4-decyloxyphenyl）-5,8- bis（2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl）quinoxaline] （P2）, are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance （NMR）, mass spectrometry （MS）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, ultraviolet-visible absorption spectrometry （UV-Vis） and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42% （595 nm）, 30% （839 nm） and 69% （1500 nm） transmittance changes （A7%）, while P2 exhibited 32% （740 nm）, 71% （2000 nm） at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.

Thermal Product of Type-E Fast Response Temperature Sensors

This paper provides practical data for thermal product values of different scratched temperature sensors that can be used for accurate transient heat transfer measurements under hypersonic flow conditions.The effect of using different scratch techniques(abrasive papers and scalpel blades)to form the sensor's junction is investigated.It was observed that the thermal product of a particular sensor depends on the Mach number,junction scratch technique, junction location and enthalpy conditions.It was demonstrated that using different scratched technique would produce different thermal product values.

Fast response ultraviolet photodetectors based on solution-processed ZnO nanocrystals

By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a rise time of 20 ns and fall time of 350 ns,which is one of the fastest response time among the reported Zn O-based photodetectors.The results reported in this paper may show great promise for fast response optoelectronic devices based on the solution-processed nanocrystals.

Fast response CdS-CdSxTe(1-x)-CdTe core-shell nanobelt photodetector

Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell nanobelt photodetector with a rise time of 11 /.is, which is the fastest among CdS based photodetectors reported previously. The improved response speed is ascribed to the sup-pressed possibilities of surface reaction resulting from the core-shell structure and heterojunction among the CdS, CdSxTel-x and CdTe. The measured response spectrum of CdS-CdSxTe1-x-CdTe core-shell nano-belt photodetector covers a wide range from 355 to 785 nm. Moreover, high responsivity （1,520 A/W） and large 3 dB bandwidth （~22.9 kHz） are obtained along with the fast response, The high performance in responsivity, sensitivity, spectral response and photoresponse speed makes this device a promising candidate for practical application in optical sensing, communication and imaging.

Fast and Slow Responses of the North Pacific Mode Water and Subtropical Countercurrent to Global Warming

Six coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are em-ployed for examining the full evolution of the North Pacific mode water and Subtropical Countercurrent (STCC) under global warming over 400 years following the Representative Concentration Pathways (RCP) 4.5. The mode water and STCC first show a sharp weakening trend when the radiative forcing increases, but then reverse to a slow strengthening trend of smaller magnitude after the radiative forcing is stablized. As the radiative forcing increases during the 21st century, the ocean warming is surface-intensified and decreases with depth, strengthening the upper ocean's stratification and becoming unfavorable for the mode water formation. Moving southward in the subtropical gyre, the shrinking mode water decelerates the STCC to the south. After the radiative forcing is stabilized in the 2070s, the subsequent warming is greater at the subsurface than at the sea surface, destabilizing the upper ocean and becoming favorable for the mode water formation. As a result, the mode water and STCC recover gradually after the radiative forc-ing is stabilized.

Fast frequency response of inverter-based resources and its impact on system frequency characteristics

The inertia response and primary frequency regulation capability of synchronous grids are declining owing to the increasing penetration of inverter-based resources. The fast frequency response(FFR) of inverter-based resources is an important mitigation option for maintaining grid security under the conditions of low inertia and insufficient primary frequency response capability. However, the understanding and technical characteristics of the FFR of inverter-based resources are still unclear. Aiming at solving the aforementioned problems, this paper proposes a definition for FFR based on the impact mechanism of FFR on system frequency. The performance requirements of FFR are clarified. Then, the effects of FFR on system frequency characteristics are further analyzed based on steady-state frequency deviation, the initial rate of change of frequency, and the maximum transient frequency deviation. Finally, the system requirements for FFR and its application effects are verified by simulating an actual bulk power grid, providing technical support for subsequent engineering application.

Immediate, Fast, and Overcome Response of the Organism in Response to Energy Osteopathy on the Model of Primary Gonarthrosis (Polyparametric and Statistical Studies)

In 26 patients with confirmed primary verified gonarthrosis(PGA),a clinical and instrumental examination was conducted to evaluate the response energy osteopathy followed by statistical processing of the data.Three types of the body’s response to treatment were identified:immediate,fast,and delayed,which,despite the different informative value of the data of the polyparametric study,allowed judging the effectiveness of the method used.

Decomposition of Fast and Slow Cloud Responses to Quadrupled CO_(2)Forcing in BCC–AGCM2.0 over East Asia

In this study,the decomposed fast and slow responses of clouds to an abruptly quadrupled CO_(2)concentration(approximately 1139 ppmv)in East Asia(EA)are obtained quantitatively by using a general circulation model,BCC–AGCM2.0.Our results show that in the total response,the total cloud cover(TCC),low cloud cover(LCC),and high cloud cover(HCC)all increased north of 40°N and decreased south of 40°N except in the Tibetan Plateau(TP).The mean changes of the TCC,LCC,and HCC in EA were–0.74%,0.38%,and–0.38%in the total response,respectively;1.05%,–0.03%,and 1.63%in the fast response,respectively;and–1.79%,0.41%,and–2.01%in the slow response,respectively.By comparison,we found that changes in cloud cover were dominated by the slow response in most areas in EA due to the changes in atmospheric temperature,circulation,and water vapor supply together.Overall,the changes in the cloud forcing over EA related to the fast and slow responses were opposite to each other,and the final cloud forcing was dominated by the slow response.The mean net cloud forcing(NCF)in the total response over EA was–1.80 W m^(–2),indicating a cooling effect which partially offset the warming effect caused by the quadrupled CO_(2).The total responses of NCF in the TP,south China(SC),and northeast China(NE)were–6.74 W m^(–2),6.11 W m^(–2),and–7.49 W m^(–2),respectively.Thus,the local effects of offsetting or amplifying warming were particularly obvious.

Moisture‑Electric–Moisture‑Sensitive Heterostructure Triggered Proton Hopping for Quality‑Enhancing Moist‑Electric Generator

Moisture-enabled electricity(ME)is a method of converting the potential energy of water in the external environment into electrical energy through the interaction of functional materials with water molecules and can be directly applied to energy harvesting and signal expression.However,ME can be unreliable in numerous applications due to its sluggish response to moisture,thus sacrificing the value of fast energy harvesting and highly accurate information representation.Here,by constructing a moisture-electric-moisture-sensitive(ME-MS)heterostructure,we develop an efficient ME generator with ultra-fast electric response to moisture achieved by triggering Grotthuss protons hopping in the sensitized ZnO,which modulates the heterostructure built-in interfacial potential,enables quick response(0.435 s),an unprecedented ultra-fast response rate of 972.4 mV s^(−1),and a durable electrical signal output for 8 h without any attenuation.Our research provides an efficient way to generate electricity and important insight for a deeper understanding of the mechanisms of moisture-generated carrier migration in ME generator,which has a more comprehensive working scene and can serve as a typical model for human health monitoring and smart medical electronics design.

High Density 3D Carbon Tube Nanoarray Electrode Boosting the Capacitance of Filter Capacitor

Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.

Fast-transient techniques for high-frequency DC–DC converters

A 30 MHz voltage-mode controlled buck converter with fast transient responses is presented.An improved differential difference amplifier(DDA)-based Type-III compensator is proposed to reduce the settling times of the converter during load transients,and to achieve near-optimal transient responses with simple PWM control only.Moreover,a hybrid scheme using a digital linear regulator with automatic transient detection and seamless loop transition is proposed to further improve the transient responses.By monitoring the output voltage of the compensator instead of the output voltage of the converter,the proposed hybrid scheme can reduce undershoot and overshoot effectively with good noise immunity and without interrupting the PWM loop.The converter was fabricated in a 0.13μm standard CMOS process using 3.3 V devices.With an input voltage of 3.3 V,the measured peak efficiencies at the output voltages of 2.4,1.8,and 1.2 V are 90.7%,88%,and 83.6%,respectively.With a load step of 1.25 A and rise and fall times of 2 ns,the measured 1%settling times were 220 and 230 ns,with undershoot and overshoot with PWM control of 72 and 76 mV,respectively.They were further reduced to 36 and 38 mV by using the proposed hybrid scheme,and 1%settling times were also reduced to 125 ns.

An efficient technique for recovering responses of parameterized structural dynamic problems

In this article,an effective technique is developed to efficiently obtain the output responses of parameterized structural dynamic problems.This technique is based on the conception of reduced basis method and the usage of linear interpolation principle.The original problem is projected onto the reduced basis space by linear interpolation projection,and subsequently an associated interpolation matrix is generated.To ensure the largest nonsingularity,the interpolation matrix needs to go through a timenode choosing process,which is developed by applying the angle of vector spaces.As a part of this technique,error estimation is recommended for achieving the computational error bound.To ensure the successful performance of this technique,the offline-online computational procedures are conducted in practical engineering.Two numerical examples demonstrate the accuracy and efficiency of the presented method.

Contingency Reserve Evaluation for Fast Frequency Response of Multiple Battery Energy Storage Systems in a Large-scale Power Grid

Recently,the fast frequency response(FFR)service by large-scale battery energy storage systems(BESSs)has been successfully proved to arrest the frequency excursion during an unexpected power outage.However,adequate frequency response relies on proper evaluation of the contingency reserve of BESSs.The BESS FFR reserve is commonly managed under fixed contracts,ignoring various response characteristics of different BESSs and their coexisting interactions.This paper proposes a new methodology based on dynamic grid response and various BESS response characteristics to optimise the FFR reserves and prevent the frequency from breaching the under-frequency load shedding(UFLS)thresholds.The superiority of the proposed method is demonstrated to manage three large-scale BESSs operating simultaneously in an Australian power grid under high renewable penetration scenarios.Further,the proposed method can identify remaining battery power and energy reserve to be safely utilised for other grid services(e.g.,energy arbitrage).The results can provide valuable insights for integrating FFR into conventional ancillary services and techno-effective management of multiple BESSs.

Rapid operando gas monitor for commercial lithium ion batteries: Gas evolution and relation with electrode materials

Internal gases caused by side reactions are crucial signals for evaluating health and safety states of Li-ion batteries(LIBs)while it is still a great challenge to timely realize accurate monitoring.To address the issues of implanting various gas sensors into commercial batteries,here a novel method is developed to fast operando monitoring gas evolution via equipping non-dispersive infrared multi-gases sensors into a sealed tank,where real commercial batteries with one open end could be settled for operating.The generated CO_(2)concentration is strongly linked with both voltage and temperature,while the concentrations of CH_(4) and C_(2)H_(4) are solely dependent on temperature.As a typical trace gas,evolution behaviors of CO_(2)have been related to 0_(2) generation from LiNi_(o.5)Mn_(0.3)CoO_(2)0_(2) positive electrode,implying stable CO_(2)release below a critical voltage of 4.5 V.By tracking CO_(2)concentration,an increased amount of Li_(2)CO_(3) was monitored on the surface of graphite negative electrode during discharge process at dfferent temperatures and cutoff voltages,which contributes to the component variation of solid electrolyte interfaces.Such operando techniques promise a plaform for well understanding the interaction of side reactions linked with gas evolution between positive and negative electrodes in commercial LIBs.