Seasonal linkage of the Southern Hemisphere extratropical climate variability to two types of ENSO

This study uses the Climate Forecast System Reanalysis(CFSR) to investigate the responses of the Southern Hemisphere(SH) extratropical climate to two types of El Nino–Southern Oscillation(ENSO)-the eastern Pacific(EP) type and the central Pacific(CP) type in different seasons. The responses are denoted by the anomalies of climate variables associated with one-standard-deviation increase in the Nino3 or Nino4 index. The results show that in austral spring the differences in the ENSO-related anomaly(ERA) patterns of atmospheric circulation between the EP ENSO period(1979–1998) and CP ENSO period(1999–2010) are mainly associated with the change in the ENSO-PSA2 relationship. Such differences affect the ERA fields of surface air temperature and mixed layer temperature, and finally result in significant differences in sea-ice concentration anomalies in the Atlantic sector. In austral summer, significant correlation exists between the variations of SAM and both of the variations of Nino3 and Nino4 in 1979–1998, while the correlation between SAM and Nino4 disappears in 1999–2010. For all seasons, the strength of the climate ERAs depend on if there are close relationship between ENSO and the major climate variation modes of the SH extratropics. For the climate variables, the ERA patterns of surface air temperature are generally controlled by surface wind anomalies and mirrored by the mixed layer temperature anomalies. The mixed layer depth anomalies are primarily modulated by surface heat flux anomalies and occasionally by anomalous wind. There are strikingly strong anomalies of surface heat flux in the autumn of 1979–1998 related to the Nino3 variation, the period when there is only significant correlation between ENSO and PSA2. There are no evidence that the SH extratropical climate variability induced by Nino3 variations are stronger in the EP-ENSO period, and that variability induced by Nino4 variations are stronger in the CP-ENSO period.

Combined DCT and Companding for PAPR Reduction in OFDM Signals

The high peak-to-average (PAPR) is one of the serious problems in the application of OFDM technology. The com-panding transform approach is a very attractive technique to reduce PAPR, but large PAPR reduction leads to a high bit error rate (BER) by the available companding transform techniques. In this paper, a joint reduction in PAPR of the OFDM signals based on combining the discrete cosine transform (DCT) with companding is proposed. In the first step of the proposed scheme, the data are transformed by a DCT into new modified data. In the second step, the proposed scheme utilizes the companding technique to further reduce the PAPR of the OFDM signal. The performance of the PAPR is evaluated using a computer simulation. The simulation results indicate that the proposed scheme may obtain about 1 dB PAPR reduction compared with the conventional companding algorithm.

Reduction PAPR of OFDM Signals by Combining Grouped DCT Precoding with PTS

The high peak-to-average power ratio (PAPR) is one of the serious problems in the application of OFDM technology. In this paper, an improved partial transmit sequence (PTS) scheme based on combining the grouped discrete cosine transform (DCT) with PTS technique is proposed. In the proposed scheme, the adjacent partitioned data are firstly transformed by a DCT into new modified data. After that the proposed scheme utilizes the conventional PTS technique to further reduce the PAPR of the OFDM signal. The performance of the PAPR is evaluated using a computer simulation. The simulation results indicate that the proposed scheme may improve the PAPR performance compared with the conventional PTS scheme, the grouped DCT scheme, and original OFDM respectively.

Iterative Detection and Decoding with PIC Algorithm for MIMO-OFDM Systems

In this paper, we propose a new iterative detection and decoding scheme based on parallel interference cancel (PIC) for coded MIMO-OFDM systems. The performance of proposed receiver is improved through the joint PIC MIMO detection and iterative detection and decoding. Its performance is evaluated based on com-puter simulation. The simulation results indicate that the performance of the proposed receiver is greatly im-proved compared to coded MIMO-OFDM systems based on VBLAST detection scheme.

Reduction PAPR of OFDM Signals by Combining SLM with DCT Transform

One of main disadvantage of OFDM is high peak-to-average power ratio (PAPR). In this paper, two effective PAPR reduction schemes are proposed. These techniques combine DCT and SLM techniques. The scheme 1 is composed of the DCT followed by SLM technique, and the DCT is used followed by conventional SLM in proposed scheme 2. Simulation results show that the proposed schemes can obtain significant PAPR reduction performance with that of ordinary SLM techniques.

Reducing the PAPR of OFDM Signals Based on SCHT Precoding

The precoding scheme based on real Hadamard transform is an effective and flexible way for reducing the peak-to-average power ratio (PAPR) of OFDM signals. However, the reduction capacity of PAPR is limited for real Hadamard transform method. In this paper, the new scheme based on complex Hadamard transform is proposed. The simulation results indicate that the proposed scheme may obtain a 1.2 dB PAPR reduction of OFDM signal with only moderate complexity compared with the real Hadamard transform.

高管从军经历对企业绿色技术创新的影响研究

基于烙印理论和高阶理论,利用沪深A股2010~2021年上市公司数据,从企业绿色创新视角切入,探究高管从军经历对企业绿色技术创新的影响效应和作用机制。研究发现:高管从军经历显著促进了企业绿色技术创新;高管从军经历通过企业社会责任和企业风险承担进而影响企业绿色技术创新;政府补贴和媒体关注强化了高管从军经历对企业绿色技术创新的促进作用;高管从军经历在非国有企业、大规模企业以及高管学历较高、任期较长时其对绿色技术创新作用更明显。研究对企业如何任用高管来推进企业绿色技术创新提供了重要的理论和现实启示。

EEG-controlled functional electrical stimulation rehabilitation for chronic stroke:system design and clinical application

Stroke is one of the most serious diseases that threaten human life and health.It is a major cause of death and disability in the clinic.New strategies for motor rehabilitation after stroke are undergoing exploration.We aimed to develop a novel artificial neural rehabilitation system,which integrates brain--computer interface(BCI)and functional electrical stimulation(FES)technologies,for limb motor function recovery after stroke.We conducted clinical trials(including controlled trials)in 32 patients with chronic stroke.Patients were randomly divided into the BCI-FES group and the neuromuscular electrical stimulation(NMES)group.The changes in outcome measures during intervention were compared between groups,and the trends of ERD values based on EEG were analyzed for BCI-FES group.Results showed that the increase in Fugl Meyer Assessment of the Upper Extremity(FMA-UE)and Kendall Manual Muscle Testing(Kendall MMT)scores of the BCI-FES group was significantly higher than that in the sham group,which indicated the practicality and superiority of the BCI-FES system in clinical practice.The change in the laterality coefficient(LC)values based onμ-ERD(ΔLCm-ERD)had high significant positive correlation with the change in FMA-UE(r=0.6093,P=0.012),which provides theoretical basis for exploring novel objective evaluation methods.

Catalytic oxidation of CO on mesoporous codoped ceria catalysts:Insights into correlation of physicochemical property and catalytic activity

Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure CeO2 were prepared by CTAB-assisted hydrothermal method for CO oxidation.XRD,SEM,EDS,BET,Raman,H2-TPR,XPS and in situ DRIFTS techniques were carried out to study the physicochemical properties and to correlate them to the activity.The doped samples maintain the cubic fluorite structure of CeO2 with high crystallinity and small crystallite size,forming Ce-based solid solutions.The obtained catalysts have large mesoporous structure with average pore size of 10-14 nm.The doped transition metal enhances the oxygen vacancies and improves reducibility of the solids.The synergistic interaction of Mn and Cu codoping induces mo re oxygen vacancies,pro moting the increase of surface adsorbed oxygen and the transfer of bulk oxygen of catalyst,thereby enhancing the catalytic activity for CO oxidation.Besides,the decomposition rate of the carbonate species which is derived from in situ DRIFTS for each catalyst can provide a measure to evaluate its catalytic activity of CO oxidation.

Determination of 4-tert-octylphenol in surface water samples of Jinan in China by solid phase extraction coupled with GC-MS

Octylphenols, considered as xenoestrogens, mainly exist as 4-tert-octylphenol （OP） in aquatic environments. The high stability and accumulation of OP in aquatic systems have caused endocrine disruption. The OP in surface water in Jinan, China was analyzed by gas chromatography-mass spectrometry （GC-MS） coupled with solid phase extraction （SPE）. Water samples were extracted by SPE on a cartridge system containing C-18 as sorbent. To increase sensitivity and selectivity, OP was derivatized to 4-tert-octyl-phenoxy silane. With the use of phenanthrene-d10 as internal standard, the detection limit based on signal-to-noise ratio （S/N = 3） was 0.06 ng/mL. The average recovery was from 84.67% to 109.7%. The precision of the method given as the relative standard deviations （RSD） was within the range 6.24%-12.96%. In the target water samples, the concentrations of OP were as follows： 15.88-71.24 ng/L for Jinxiuchuan Reservoir, 3.850-26.68 ng/L for the city moat, 6.930-41.56 ng/L for Daming Lake, 66.03-474.2 ng/L for Xiaoqing River, 14.66-17.72 ng/L for the Yellow River, and 10.60-26.43 ng/L for Queshan Reservoir. The Xiaoqing River was seriously polluted due to the discharge of wastewater from Jinan. Jinxiuchuan Reservoir had a higher concentration of OP compared with the Yellow River and Queshan Reservoir, which is ascribed to the surrounding human activities. These data are reported for the first time, providing strong support for the control of OP pollution in Jinan.

A novel ceria hollow nanosphere catalyst for low temperature NOx storage

In this work,a highly active CeO_(2) catalyst with hollow nanosphere morphology for low temperature NO_(x) storage was prepared by a surfactant-assisted solvothermal reaction.The physicochemical properties of ceria samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N_(2) adsorption–desorption,H_(2)-temperature programmed reduction(H_(2)-TPR),X-ray photoelectron spectroscopy(XPS)and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The as-prepared CeO_(2) nanosphere possesses excellent NO oxidation capacity,smaller mesopores,better reducibility and more surface Ce^(3+)content.Compared with CeO_(2) with nanorod and nanoparticle morphologies,CeO_(2) nanosphere shows better intrinsic low temperature NO_(x) trapping performance,with a wide operating temperature window(150–300℃),high NO_(x) adsorption capacity(NAC,640–745μmol/g)and high NO_(x) storage capacity(NSC,250–350μmol/g).Two reaction pathways are speculated for NO_(x) adsorption on CeO_(2) nanosphere,including“nitrate route”and“nitrite route”.The thermally unstable surface nitrites formed on the CeO_(2) nanosphere allow ceria to release more NO_(x) during the desorption process.The present work provides a new ceria morphology for NO_(x) traps,which may become a potential excellent NO_(x) storage material.