A Frequency Domain Based Signal Combining Method for Distributed Antenna Arraying

Distributed antenna arraying is a promising technology for weak signal reception. The received signals from different antennas are aligned and combined to improve the receiving signal-to-noise ratio(SNR). However, the combining performance is serious degraded by the difference of sampling frequency between antennas. In this paper, a frequency domain based signal combining method is proposed to solve this problem. The unaligned sampled data in time domain of the received signals are transformed to frequency domain using fast Fourier transform(FFT). The received signals can be aligned in frequency domain when their spectrum resolutions are the same. Therefore the received signals with the same total sampling time can be aligned and combined in frequency domain and then the combined signal is recovered using inverse fast Fourier transform(IFFT). Numerical simulations with two typical modulation types, i.e., PSK and PCM/BPSK/PM, prove the validity and robustness of this method.

Visualization on electrified micro-jet instability from Taylor cone in electrohydrodynamic atomization

The cone-jet in electrohydrodynamic atomization has been widely applied into numerous industrial fields owing to micro-sized drops with narrow distribution and high charge.The electrified jet emits from a single capillary sheathed with quartz tube is visualized versus operating parameters and physical properties,and breakup instabilities are also discussed.The range of operating parameters for a steady conejet broadens,as well as the minimum flow rate.Taylor cone angle decreases with an increase in flow rate,while increases as electric potential increasing.The jet breakup length decreases with an increase in flow rate and conductivity,while increases as electric potential increasing.The diffusion angle increases as flow rate increasing,while decrease as electric potential and conductivity increasing.Much clearer whipping instabilities are observed with an increase in“electro-Weber”number and conductivity.The completion in disturbance or/and suppression from axial and radial stresses,drag force dominates the variation.Meanwhile,for a large flow rate,the transition from varicose instabilities to whipping instabilities is found.The whipping instabilities are clearly observed for high conductivity due to much more free ions in liquid.For much higher conductivity,an intermittent electrified jet appears and shows an umbrella plume,and breakup length sharply shortens.

Research on Temperature Field Reconstruction Based on RBF Approximation with Polynomial Reproduction Considering the Refraction Effect of Sound Wave Paths

The temperature field distribution directly reflects the combustion condition in a furnace.In this paper,acoustic thermometry to reconstruct temperature distribution is investigated.A method based on radial basis function approximation with polynomial reproduction(RBF-PR)is proposed in order to improve the accuracy and stability of the method based on RBF approximation.In addition,the refraction effect of sound wave paths is considered in the process of reconstruction.The curved lines with refraction effect are numerically calculated by solving differential equations,which show that sonic waves curve towards the zones of higher temperature.The reconstructed performance is validated via numerical simulation using four temperature distribution models.Results and analysis show that the proposed method has much greater accuracy than the method based on RBF approximation,and when considering the effect of refraction,our method can reconstruct more excellent reconstruction performance than others,which do not take into account the refraction effect of sound wave paths.

The Analysis of Clinical Features of Systemic Lupus Erythematosus (SLE) in Children

Objective:Observe the clinical characteristics of children with SLE,namely,to observe the symptoms and laboratory examinations,such as blood routine,blood lipid,immunoglobulin,complement,autoantibodies,serum 25(OH)D and other indicators,and to explore the clinical characteristics,the difference and the significance of vitamin D supplements between male and female SLE patients in children respectively.Methods:We enrolled 64 cases of SLE patients in children who were admitted into the department of pediatrics and rheumatology of the third affiliated hospital of sun yat-sen university in guangzhou from May 1,2011 to February 1,2019,They were analyzed retrospectively,adoptingΧ²test for statistical analysis.Results:64 cases of SLE in children,which included 10 cases of male and 54 cases of female.Clinical manifestations:facial skin rash in 48 patients(75%),fever in 38 cases(59.4%),arthritis in 28 cases(43.8%),oral ulcer in 18 cases(28.1%),serositis in13 cases(20.3%),and the sun allergy in 9 cases(14.1%),the damage of central nervous system in 7 cases(10.9%).Laboratory examination:30 cases of leukopenia(46.9%),anemia in 30 cases(46.9%),thrombocytopenia in 12 cases(18.8%),hematuria in 18 cases(28.1%),proteinuria in 33 cases(51.2%),6 patients with renal impairment(9.4%),antinuclear antibody positive in 63 cases(98.4%),anti-double-stranded DNA(dsDNA)antibody positive in 48 cases(75%),anti SSA antibody positive in 44 cases(68.7%),SSB antibody positive in 33 cases(51.6%),Sm antibody positive in 40 cases(62.5%),nucleosome antibody positive in 28 cases(43.8%).Among these children,male SLE patients were higher than female children with SLE in the damage of kidney,Sm antibodies and resisting nucleosome antibody positive rates(Χ²=4.451,8.336,6.803,P<0.05),the female children with SLE was higher than male SLE Children in the anti-SSB antibody positive rate(Χ²=4.945,P<0.05).In 64 cases of SLE children,which included 52 cases were lower than the normal level of serum 25(OH)D measurements,12 cases were in the normal lower limit of serum 25(OH)D measurements,at the same time,the female SLE.Patients was higher than male children with SLE in the reduce rate of serum 25(OH)D(Χ²=8.351,P<0.05).Conclusion:Male SLE patients which appeared damage of kidney easier than female patients,the proteinuria was the most common in the damage of kidney.Resistance to Sm antibodies which was the risk factor of renal injury with higher incidence in male children with SLE;Anti nucleosome antibody which was the risk factor for the disease activity in male children with SLE were higher than female children with SLE.It was estimated that the risk of Sjogren’s syndrome appeared in female with SLE were higher than that in male SLE children.In this retrospective study,the serum 25(OH)D levels were significantly lower in children with SLE,and vitamin D supplementation was required.

Transmission properties in Fibonacci quasi-periodic photonic crystal containing negative-zero-positive index metamaterials

The transmission properties in Fibonacci quasi-periodic photonic crystals containing negative-zero-positive index metamaterials(NZPIM)are investigated systematically.Because of linear dispersion,an asymmetric band gap appears near the optical Dirac point(DP)only at an oblique incidence.Zero-n gaps and Bragg gaps exist when the refractive indexes of NZPIM are negative and positive,respectively.We also obtain gaps induced by total reflection on both sides of the DP gap.The corresponding Goos-Hänchen(GH)shifts and phase variations are also demonstrated in detail.It is shown that the characteristics of the band gaps,GH shifts,and phase variations depend crucially on the incident angle,number of periods,and layer thickness.

Characterization of personal exposure concentration of fine particles for adults and children exposed to high ambient concentrations in Beijing, China

In China, the health risk from overexposure to particles is becoming an important public health concern. To investigate daily exposure characteristics to PM 2.5 with high ambient concentration in urban area, a personal exposure study was conducted for school children, and office workers in Beijing, China. For all participants （N = 114）, the mean personal 24-hr exposure concentration was 102.5, 14.7, 0.093, 0.528, 0.934, 0.174 and 0.703 μg/m 3 for PM 2.5 , black carbon, Mn, Al, Ca, Pb, and Fe. Children’s exposure concentrations of PM 2.5 were 4–5 times higher than those in related studies. The ambient concentration of PM 2.5 （128.5 μg/m 3 ） was significantly higher than the personal exposure concentration （P 0.05）, and exceed the reference concentration （25 μg/m 3 ） of WHO air quality guideline. Good correlation relationships and significant differences were identified between ambient concentration and personal exposure concentration. The relationships indicate that the ambient concentration is the main factor influencing personal exposure concentration, but is not a good indicator of personal exposure concentration. Outdoor activities （commute mode, exposure to heating, workday or weekend travel） influenced personal exposure concentrations significantly, but the magnitude of the influence from indoor activities （exposure to cooking） was masked by the high ambient concentrations.

Hybrid OCS/OBS interconnect in intra-data-center network

We report on a data center network(DCN) architecture based on hybrid optical circuit switching(OCS) and optical burst switching(OBS) interconnect for dynamic DCN connectivity provisioning. With the combination of the centralized and distributed control of the software-defined optical networks, the proposed interconnect can achieve unprecedented flexibility in dealing with both mice and elephant flow in the DCN. Numerical simulation is employed to investigate the performance of the proposed architecture. The results show that the OBS module has preferable performance in dealing with a larger burst packet, and the throughput is constrained by the capacity of the server random access memory module.