Extended Range(10–30 Days) Heavy Rain Forecasting Study Based on a Nonlinear Cross-Prediction Error Model

Extended range （10-30 d） heavy rain forecasting is difficult but performs an important function in disaster prevention and mitigation. In this paper, a nonlinear cross prediction error （NCPE） algorithm that combines nonlinear dynamics and statistical methods is proposed. The method is based on phase space reconstruction of chaotic single-variable time series of precipitable water and is tested in 100 global cases of heavy rain. First, nonlinear relative dynamic error for local attractor pairs is calculated at different stages of the heavy rain process, after which the local change characteristics of the attractors are analyzed. Second, the eigen-peak is defined as a prediction indicator based on an error threshold of about 1.5, and is then used to analyze the forecasting validity period. The results reveal that the prediction indicator features regarded as eigenpeaks for heavy rain extreme weather are all reflected consistently, without failure, based on the NCPE model; the prediction validity periods for 1-2 d, 3-9 d and 10-30 d are 4, 22 and 74 cases, respectively, without false alarm or omission. The NCPE model developed allows accurate forecasting of heavy rain over an extended range of 10-30 d and has the potential to be used to explore the mechanisms involved in the development of heavy rain according to a segmentation scale. This novel method provides new insights into extended range forecasting and atmospheric predictability, and also allows the creation of multi-variable chaotic extreme weather prediction models based on high spatiotemporal resolution data.

Analysis and Optimization of Key Dimensions of Co-Axial Dual-Mechanical-Port Flux-Switching Permanent Magnet Machines for Fuel-Based Extended Range Electric Vehicles

In this paper,key dimensions of a co-axial dual-mechanical-port flux-switching permanent magnet(CADMP-FSPM)machine for fuel-based extended range electric vehicles(ER-EVs),including split ratio,stator/rotor pole arcs,rotor yoke thickness,etc.,are analyzed and optimized.Firstly,the topologies and operation principles of an exampled 3-phase CADMP-FSPM are introduced briefly,in which an inner-rotor FSPM machine with 12-stator-slots/10-rotor-poles for high-speed generation and an outer-rotor FSPM machine with 12-stator-slots/22-rotor-poles for low-speed motoring are assembled co-axially.Then,the relationship between the key dimensions and electromagnetic performance,particularly for electromagnetic torque(power),of the CADMP-FSPM machine is studied by 2D-finite element analysis(FEA).Further,the reasonable matches of split ratio,rotor/stator pole arcs and rotor yoke are determined and the original CADMP-FSPM machine is optimized correspondingly.Finally,the static characteristics,including no-load PM flux-linkage,electro-motive-force(EMF),winding inductances,cogging torques and electromagnetic torques,of the original and optimized machines are compared by 2D-FEA.The results verify that the optimized CADMP-FSPM machine can exhibit improved torque characteristics than the original one,i.e.,the torque ripples of the inner and outer machines can be reduced by 22.7%and 4.7%,respectively,and the average torque of the inner and outer machines can be increased by 0.43Nm and 2Nm,respectively.

Error Sensitivity Analysis in 10–30-Day Extended Range Forecasting by Using a Nonlinear Cross-Prediction Error Model

Extended range forecasting of 10-30 days, which lies between medium-term and climate prediction in terms of timescale, plays a significant role in decision-making processes for the prevention and mitigation of disastrous met- eorological events. The sensitivity of initial error, model parameter error, and random error in a nonlinear cross- prediction error （NCPE） model, and their stability in the prediction validity period in 1 0-30-day extended range fore- casting, are analyzed quantitatively. The associated sensitivity of precipitable water, temperature, and geopotential height during cases of heavy rain and hurricane is also discussed. The results are summarized as follows. First, the initial error and random error interact. When the ratio of random error to initial error is small （10＂5-10-2）, minor vari- ation in random error cannot significantly change the dynamic features of a chaotic system, and therefore random er- ror has minimal effect on the prediction. When the ratio is in the range of 10-1-2 （i.e., random error dominates）, at- tention should be paid to the random error instead of only the initial error. When the ratio is around 10 2-10-1, both influences must be considered. Their mutual effects may bring considerable uncertainty to extended range forecast- ing, and de-noising is therefore necessary. Second, in terms of model parameter error, the embedding dimension m should be determined by the factual nonlinear time series. The dynamic features of a chaotic system cannot be depic- ted because of the incomplete structure of the attractor when m is small. When m is large, prediction indicators can vanish because of the scarcity of phase points in phase space. A method for overcoming the cut-off effect （m 〉 4） is proposed. Third, for heavy rains, precipitable water is more sensitive to the prediction validity period than temperat- ure or geopotential height; however, for hurricanes, geopotential height is most sensitive, followed by precipitable water.

Combining Cubic Spline Interpolation and Fast Fourier Transform to Extend Measuring Range of Reflectometry

The reflectometry is a common method used to measure the thickness of thin films. Using a conventional method,its measurable range is limited due to the low resolution of the current spectrometer embedded in the reflectometer.We present a simple method, using cubic spline interpolation to resample the spectrum with a high resolution,to extend the measurable transparent film thickness. A large measuring range up to 385 m in optical thickness is achieved with the commonly used system. The numerical calculation and experimental results demonstrate that using the FFT method combined with cubic spline interpolation resampling in reflectrometry, a simple,easy-to-operate, economic measuring system can be achieved with high measuring accuracy and replicability.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P2O7 unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

A More Natural Way of Seeing: Visual Performance of Three Presbyopia Correcting Intraocular Lenses

Purpose: To compare the visual and refractive outcomes, patient satisfaction and spectacle independence between three novel designs of diffractive IOLs. Method: Prospective study including 150 patients with implantation of three IOLs: trifocal diffractive IOL AT LISA tri 839 MP (ATLISA, n = 50), trifocal diffractive IOL PhysIOL FineVision (FineVision, n = 50) and the extended range of vision IOL Tecnis Symfony ZRX00 (Symfony, n = 50). Patients were followed up for 6 months after surgery. Major parameters were monocular and binocular uncorrected (UDVA) and corrected (CDVA) distance, uncorrected (UIVA) and distance corrected (DCIVA) intermediate (80 cm), and uncorrected (UNVA) and distance corrected (DCNVA) near (40 cm) visual acuities (UNVA), contrast sensitivity (CS), defocus curve as well as patient satisfaction and spectacle use. Results: Mean postoperative decimal UDVA was 1.01 for Symfony, 0.96 for ATLISA and 0.95 for the FineVision IOL. Postoperative UIVA was 0.95 with Symfony, 0.72 with ATLISA and 0.85 with the FineVision IOL. Postoperative UNVA was 0.96 with the FineVision, 0.72 with the ATLISA and 0.63 with the Symfony IOL. The Symfony defocus curve showed the smoothest profile. Mean mesopic CS was 0.84 log units with the Symfony, 0.83 with the ATLISA (0.83) and 0.65 with the FineVision IOL. Mean photopic CS with the Symfony, ATLISA and FineVision was 1.05, 0.85 and 0.69 log units, respectively. Twenty percent of the patients with the ATLISA and FineVision IOLs and 5.6% of the Symfony patients reported halos and glare as troublesome or disabling. Reading glasses were frequently used by 5.6% of the Symfony patients. All patients with the trifocal IOLs reported to be spectacle-free for any distance. Conclusion: All 3 IOLs produce excellent results with high levels of spectacle independence. The Symfony produces better levels of distance and intermediate visual acuity, whereas the trifocal IOLs produced better near vision. Higher frequency of dysphotopsia was seen with the trifocal IOLs.

Influence of heating on the discharge characteristics of a hollow cathode

Hollow cathodes are widely used as electron sources and neutralizers in ion and Hall electric propulsion.Special applications such as commercial aerospace and gravitational wave detection require hollow cathodes with a very wide discharge current range.In this paper,a heater is used to compensate for the temperature drop of the emitter at low current.The self-sustained current can be extended from 0.6 to 0.1 A with a small discharge oscillation and ion energy when the flow rate is constant.This is also beneficial for long-life operation.However,when the discharge current is high(>1 A),heating can cause discharge oscillation,discharge voltage and ion energy to increase,f urther,combined with a rapid decline of pressure inside the cathode and an increase in the temperature in the cathode orifice plate,electron emission in die orifice and outside the orifice increases and the plasma density in the orifice decreases.This leads to a change in the cathode discharge mode.

ComplexTrans-Global Rail-Road Transportation System Economical and Clustered Individual and Individualised Public Transport also Prevents the Spread of Covid 19

Land transport can no longer meet the requirements.European transport can be described by these words−crowded motorways and cities,dangerous emissions,ubiquitous traffic accidents,delays,expensive railways.Solutions are being sought to transfer a large part of passengers and especially freight transport to(high-speed)rail,and efforts are moving towards electromobility,car-sharing,5G-connectivity,autonomous driving,MaaS(Mobility as a Service)-coordinated transport or hyperloop-type solutions.However,all these solutions have additional challenges and limitations.Solutions are not being searched where they really exist-in the mutual adaptation of road and rail vehicles and their deep cooperation.The ComplexTrans project shows that simply adapting the dimensions and functions of road and rail vehicles can eliminate(or at least significantly reduce)all the problems of existing land transport.The main features of the ComplexTrans system are sufficient parking spaces,reduction of urban and non-urban congestion,electric vehicles with unlimited range and cheaper than standard cars,cheaper and more accessible battery charging,“autonomous ride”,solving the overlap between passenger and freight rail transport and making it self-financing,transferring intercity freight transport to rail,replacing part of continental air transport and many others.The cost-effective and clustered individual transport and individualised public transport of the ComplexTrans system also bring very significant reductions in the risk of transmission of covid-19 and other contagious diseases during transport.

带Range-Extender纯电动汽车动力系统设计

引入Range-Extender概念,阐述纯电动汽车前期开发过程中动力系统参数的设计过程,旨在为纯电动汽车动力系统参数开发提供参考。

Plasmonic silicon quantum dots extend photodetection into mid-infrared range

Nowadays the development of Internet of Things(IoT)and defense technologies imperatively needs high-performance photodetectors that can work in a broadband wavelength range,in particular,covering the mid-infrared(MIR)region[1].This generates great interest in the incorporation of a series of novel optoelectronic materials and structures into the photodetectors.Graphene and colloidal quantum dots(QDs)are key players among novel materials used to fabricate high-performance photodetectors[2–4].By taking advantage of the high mobility of

Micro Gas Turbine Range Extender Performance Analysis Using Varying Intake Temperature

A micro gas turbine(MGT)can potentially be an alternative power source to the conventional internal combustion engine as a range extender in hybrid electric vehicles.The integration of the MGT into a hybrid vehicle needs a new approach for technical validation requirements compared to the testing of an internal combustion engine.Several attributes of the MGT are predicted to cause concerns for vehicle sub-system requirements such as high ambient temperature and start-stop behaviour.This paper describes the results from specially developed experimental techniques for testing the MGT in a typical automo-tive environment.A black box MGT was used in this study for performance investigation during hot and cold starts.The MGT was instrumented and fitted with automotive standard components to replicate typical vehicle operational conditions.The intake air temperature was varied between 10 and 24°C.A significant reduction in the power output of the MGT was observed as the intake temperature was increased.The proposed case scenario caused a reduction in nitrogen oxide emis-sions in the range of 0.02−0.04 g/km because of the lower combustion temperature at high intake temperature.However,hydrocarbon and carbon monoxide emissions have not shown a noticeable reduction during the power output degradation.The experimental results have highlighted the potential issues of using the MGT at higher intake temperatures and suggest design change to take the effect of higher engine bay temperature into account.