Harmonicity Spectrum

Perceiving harmonic information (especially weak harmonic information) in time series has important scientific and engineering significance. Fourier spectrum and time-frequency spectrum are commonly used tools for perceiving harmonic information, but they are often ineffective in perceiving weak harmonic signals because they are based on energy or amplitude analysis. Based on the theory of Normal time-frequency transform (NTFT) and complex correlation coefficient, a new type of spectrum, the Harmonicity Spectrum (HS), is developed to perceive harmonic information in time series. HS is based on the degree of signal harmony rather than energy or amplitude analysis, and can therefore perceive very weak harmonic information in signals sensitively. Simulation examples show that HS can detect harmonic information that cannot be detected by Fourier spectrum or time-frequency spectrum. Acoustic data analysis shows that HS has better resolution than traditional LOFAR spectrum.

Novel Mg-Bi-Mn wrought alloys:The effects of extrusion temperature and Mn addition on their microstructures and mechanical properties

Designing and developing the Mg alloys with low cost and high performance is of the great significance.Novel Mg-1Bi-xMn(x=0,1and 2 wt.%)extruded alloys,in this work,were fabricated at different extrusion temperatures(220,250 and 300℃).The effects of extrusion temperature and Mn addition on the microstructures and mechanical properties of extruded alloys at room temperature were investigated.The results showed that decreasing the extrusion temperature could refine the average grain size,weaken the basal fiber texture intensity and improve the microstructural homogeneity of extruded alloys.When the Mn element was added to the Mg-1Bi alloy,the average grain size further reduced.Simultaneously,the number fraction of low angle grain boundaries(LAGBs)increased,along with the occurrence of regions without dynamic recrystallization(unDRX).The combined effects of grain refinement and coarse unDRXed structure made the textures of the extruded Mg-1Bi-xMn alloys never obviously change.Besides few large size un-dissolved second phases,fine Mg_(3)Bi_(2) and α-Mn phases were precipitated in the extruded Mg-1Bi-xMn alloys and partial nano-scaleα-Mn particles pined at grain boundaries(GBs)to effectively impede the migration of GBs for grain refinement.Microstructural variations determined the extruded Mg-1Bi-2Mn alloy to exhibit the highest yield strength of~319.2 MPa with the appropriate elongation-to-failure of~13%at the extrusion temperature of 220℃,and they enabled the extruded Mg-1Bi-1Mn alloy to show the highest elongation-to-failure of~26%without the obvious loss of yield strength of~252.1 MPa.

On Inversion of Continuous Wavelet Transform

This study deduces a general inversion of continuous wavelet transform (CWT) with timescale being real rather than positive. In conventional CWT inversion, wavelet’s dual is assumed to be a reconstruction wavelet or a localized function. This study finds that wavelet’s dual can be a harmonic which is not local. This finding leads to new CWT inversion formulas. It also justifies the concept of normal wavelet transform which is useful in time-frequency analysis and time-frequency filtering. This study also proves a law for CWT inversion: either wavelet or its dual must integrate to zero.

Rising trends of global precipitable water vapor and its correlation with flood frequency

Using 4 global reanalysis data sets, significant upward trends of precipitable water vapor(PWV) were found in the 3 time periods of 1958-2020, 1979-2020, and 2000-2020. During 1958-2020, the global PWV trends obtained using the ERA5 and JRA55 data sets are 0.19 ± 0.01 mm per decade(1.15 ± 0.31%)and 0.23 ± 0.01 mm per decade(1.45 ± 0.32%), respectively. The PWV trends obtained using the ERA5,JRA55, NCEP-NCAR, and NCEP-DOE data sets are 0.22 ± 0.01 mm per decade(1.18 ± 0.54%),0.21 ± 0.00 mm per decade(1.76 ± 0.56%), 0.27 ± 0.01 mm per decade(2.20 ± 0.70%) and 0.28 ± 0.01 mm per decade(2.19 ± 0.70%) for the period 1979-2020. During 2000-2020, the PWV trends obtained using ERA5, JRA55, NCEP-DOE, and NCEP-NCAR data sets are 0.40 ± 0.25 mm per decade(2.66 ± 1.51%),0.37 ± 0.24 mm per decade(2.19 ± 1.54%), 0.40 ± 0.26 mm per decade(1.96 ± 1.53%) and 0.36 ± 0.25 mm per decade(2.47 ± 1.72%), respectively. Rising PWV has a positive impact on changes in precipitation,increasing the probability of extreme precipitation and then changing the frequency of flood disasters.Therefore, exploring the relationship between PWV(derived from ERA5 and JRA55) change and flood disaster frequency from 1958 to 2020 revealed a significant positive correlation between them, with correlation coefficients of 0.68 and 0.79, respectively, which explains the effect of climate change on the increase in flood disaster frequency to a certain extent. The study can provide a reference for assessing the evolution of flood disasters and predicting their frequency trends.

Inductive effect of hydroxyl safflower yellow-A on apoptosis in abnormal HUVEC via the mitochondrial pathway

Objective:To investigate the mechanism by which hydroxyl safflower yellow A,an active component of safflower (Carthamus tinctorius L.),promotes apoptosis in abnormal human umbilical vein endothelial cells (HUVECs).Methods:Supernatant of BGC-823 was used to stimulate HUVECs to establish a model of abnormal proliferation of HUVECs.After determining an ideal concentration of HSYA by MTT assay,apoptosis was detected with flow cytometry and TUNEL assay.Mechanism of apoptosis was assessed using quantitative real-time polymerase chain reaction,Western blot,and ELISA.Results:A range of concentrations of HSYA inhibited proliferation and promoted apoptosis of abnormal HUVECs.As the rate of apoptosis increased,mRNA expression of caspase-3 increased while expression of mutant p53 decreased.HSYA had no effect on Fas gene expression.Analogously,protein expression of Bax was increased while those of Bcl-2,Fas,and Fas-L were decreased.Conclusions:HSYA appears to induce apoptosis of HUVECs with the stimulation of the supematant of tumor cells.The mechanism of apoptosis by HSYA may involve activation of the mitochondrial apoptotic pathway and regulation of the expressions of Bcl-2,Bax,and p53.

Atomization characteristics of pyrolysis oil derived from waste tires

The atomization characteristics play a key role in the highly efficient combustion of pyrolysis oil derived from waste tires.In this study,the fuel properties of tire pyrolysis oil(TPO)were initially studied,and then a high-speed camera and a phase Doppler particle analyzer were employed to characterize the atomization feature of TPO.The influence of pressure and nozzle orifice diameter on atomization characteristics such as spray angle,droplet velocity,and droplet size distribution was investigated.The results showed that TPO had a high calorific value of about 43.6 MJ/kg and a low viscosity of 3.84×10^(–6)m^(2)/s at 40℃,which made it have the potential to be used as an alternative fuel.Higher pressure expanded the spray angle and extended the spray in both the axial and radial directions.With increasing pressure,spray angle and droplet velocity raised,and the increase in crushing effect of air reduced the Sauter mean diameter(SMD)of the droplets.To obtain proper atomization quality for combustion,the pressure is expected to be higher than 1.25 MPa.With increasing nozzle orifice diameter,droplet velocity increased,and the SMD of the droplets increased as well due to weakened crushing effect of the orifice.Therefore,the pressure must be increased to maintain the atomization quality when using a nozzle with a larger orifice.Due to the lower viscosity,the velocity and particle size distribution of TPO droplets after atomization were smaller than those of diesel droplets.The extremely small carbon black contained in TPO also contributed to the breaking of droplets and played a certain role in the size reduction of the oil droplets,but it may cause the risk of nozzle blockage.In summary,TPO showed great atomization characteristics for alternative fuel applications.

Effect of gradient microstructure on the bendability of AZ31 alloy sheet

Extensive researches have elucidated the pronounced benefits of gradient microstructures for the me-chanical properties of metallic materials.However,the ramifications of gradient microstructures on formability,particularly regarding their effects on bendability,remain inadequately understood.In this work,the effects of gradient microstructure on the bendability of AZ31 Mg alloy sheet are systematically investigated by comparing the microstructure evolution and strain distribution in the sheets with uni-form microstructure(grain size=12.8 μm and 91.3 μm)and gradient microstructure(grain size=11.5-75.4 μm).The results show that the bendability of the sheet with gradient microstructure is significantly improved when the fine grains(FGs)are placed at the outer side(TBE-FG sample)and the bendability is increased by 93.1%compared to the sample with fine and uniform microstructure(CE-FG sample).With coarse grains(CGs)placed at the inner side,the strain at the compressive region of the TBE-FG sample is higher than its counterparts,while the tensile strain at the extended region is lowest among the four samples.Quasi-in-situ bending experiments reveal that the CGs at the inner side of the TBE-FG sample undergo more twinning.Moreover,the increment of residual dislocation density at the outer side of the TBE-FG sample is lower than those of other samples,which extends the bending potential.This work provides a novel perspective to improve the bendability of the Mg alloy sheet.

Effects of(Mg_(1/3)Sb_(2/3))^(4+)substitution on the structure and microwave dielectric properties of Ce_(2)Zr_(3)(MoO_(4))_(9) ceramics

Ce2[Zr_(1-x)(Mg_(1/3)Sb_(2/3))_(x)]_(3)(MoO_(4))_(9)(0.02≤x≤0.10)ceramics were prepared by the traditional solid-state method.A single phase,belonging to the space group of R3c,was detected by using X-ray diffraction at the sintering temperatures ranging from 700 to 850℃.The microstructures of samples were examined by applying scanning electron microscopy(SEM).The crystal structure refinement of these samples was investigated in detail by performing the Rietveld refinement method.The intrinsic properties were calculated and explored via far-infrared reflectivity spectroscopy.The correlations between the chemical bond parameters and microwave dielectric properties were calculated and analyzed by Phillips-van Vechten-Levine(P-V-L)theory.Ce_(2)[Zr_(0.94)(Mg_(1/3)Sb_(2/3))_(0.06)]_(3)(Mo0_(4))_(9)ceramics with excellent dielectric properties were sintered at 725℃for 6 h(εr=10.37,Q×f=71,748 GHz,andτf=-13.6 ppm/℃,εr is the dielectric constant,τf is the quality factor,and rf is the temperature coefficient of resonant frequency).

Structure characteristics and microwave dielectric properties of Pr_(2)(Zr_(1-x)Ti_(x))_(3)(MoO_(4))_(9) solid solution ceramic with a stable temperature coefficient

Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)(x=0.1-1.0)ceramics were prepared via a conventional solid-state method,the dependence of crystal structure and bond characteristics on microwave dielectric properties was investigated systemically.The X-ray diffraction patterns indicated that the single-phase Pr_(2)Zr_(3)(MoO_(4))_(9)structure was formed in all the specimens.As the Ti^(4+)content increased,the lattice volume gradually decreased,which was ascribed to the fact that the ionic radius of Ti^(4+)was smaller than that of Zr^(4+).Notably,outstanding microwave dielectric properties withεr of 10.73-16.35,Q·f values of 80,696-18,726 GHz and minorτ_(f) values−14.1-−2.6 ppm/℃were achieved in Pr_(2)(Zr_(1−x)Ti_(x))_(3)(MoO_(4))_(9)ceramics.Theε_(r) increased with the rising x values,which was associated with the increase ofα/Vm values.The decreasing Q·f was affected by the decline of lattice energy of[Zr/TiO_(6)]octahedral.Theτf value was dominated by[Zr/TiO_(6)]octahedral distortion,Mo-O bond energy,bond strength and B-site bond valence.Furthermore,infrared reflection spectra suggested that the properties were mainly caused by the absorption of phonon,and the dielectric loss could be further reduced by optimizing the experimental process.

Identification of two novel B-cell epitopes on the nucleocapsid protein of porcine deltacoronavirus

Dear Editor,Porcine deltacoronavirus(PDCoV)is a novel discovered swine enteric coronavirus which can cause diarrhea and dehydration in pigs,particularly in neonatal piglets(Jung et al.,2016).At present,there are no commercial vaccines available for PDCo V.To control PDCoV transmission and perform antiviral therapy efficiently,a rapid and accurate diagnostic method to detect PDCo V is needed.

Relating Initial Texture to Deformation Behavior During Cold Rolling and Static Recrystallization Upon Subsequent Annealing of an Extruded WE43 Alloy

Deformation behaviors during cold rolling and static recrystallization behaviors upon subsequent annealing of an extruded WE43 alloys with different initial textures were investigated in this study.Three types of differently textured WE43 initial alloys were labeled as samplesⅠ,ⅡandⅢ.The results showed that multiple twinning modes and basal slip dominated the deformation of samples during cold rolling.Cold-rolled sampleⅠactivated the larger number of double twins with high strain energy,accompanied by the more uniform strain distribution,than cold-rolled samplesⅡandⅢ.During subsequent annealing,recrystallized grains preferentially occurred in double twins,twin-twin intersections and grain boundaries,thereby making cold-rolled sampleⅠhave the more rapid recrystallization rate.Similar recrystallization textures formed in three types of cold-rolled samples at the recrystallization nucleation stage,and they never largely changed with the annealing time due to the uniform grain growth induced by the solute drag and the precipitation pinning at grain boundaries.After full recrystallization,the grain growth was controlled by the solute drag,instead of precipitates which were re-dissolved into the matrix.Finally,the nucleation and growth kinetics of static recrystallization were calculated,and the effects of initial texture on activation energies of recrystallization nucleation and growth were discussed.

Design and implementation of a reconfigurable mixed-signal SoC based on field programmable analog arrays

This work presents a reconfigurable mixed-signal system-on-chip（SoC）, which integrates switched-capacitor-based field programmable analog arrays（FPAA）, analog-to-digital converter（ADC）, digital-to-analog converter, digital down converter, digital up converter, 32-bit reduced instruction-set computer central processing unit（CPU） and other digital IPs on a single chip with 0.18 μm CMOS technology. The FPAA intellectual property could be reconfigured as different function circuits, such as gain amplifier, divider, sine generator, and so on. This single-chip integrated mixed-signal system is a complete modern signal processing system, occupying a die area of 7 × 8 mm^2 and consuming 719 mW with a clock frequency of 150 MHz for CPU and 200 MHz for ADC/DAC. This SoC chip can help customers to shorten design cycles, save board area, reduce the system power consumption and depress the system integration risk, which would afford a big prospect of application for wireless communication.