Fast GNSS Acquisition Algorithm Based on SFFT with High Noise Immunity

The Global Navigation Satellite System(GNSS)has been widely used in various fields.To achieve positioning,the receiver must first lock the satellite signal.This is a complicated and expensive process that consumes a lot of resources of the receiver.For this reason,this paper proposes a new fast acquisition algorithm with High Signal-tonoise ratio(SNR)performance based on sparse fast Fourier transform(HSFFT).The algorithm first replaces the IFFT process of the traditional parallel code phase capture algorithm with inverse sparse fast Fourier transform(ISFFT)with better computing performance,and then uses linear search combined with code phase discrimination to replace the positioning loop and the estimation loop with poor noise immunity in ISFFT.Theoretical analysis and simulation results show that,compared with the existing SFFT parallel code phase capture algorithm,the calculation amount of this algorithm is reduced by 19%,and the SNR performance is improved by about 5dB.Compared with the classic FFT parallel code phase capture algorithm,the calculation amount of the algorithm in this paper is reduced by 43%,and when the capture probability is greater than 95%,the SNR performance of the two is approximately the same.

Relationship between Atrial Tissue Remodeling and ECG Features in Atrial Fibrillation

The difference in the atrial organizational structure between patients with atrial fibrillation (AF) and those with sinus rhythm was investigated.In order to analyze the rationality in explaining the electrocardiogram (ECG) characteristics of AF with statistics data or tissue remodeling model,and the logical relationship between the hypothesis of pulmonary veins (PV) muscle sleeves and that of multi wavelets in mechanism of AF,we examined the expression of collagen volume fraction of type I (CVF-I ) with picrosirius red staining,connexin 40 (Cx40) by immunohistochemistry,and intercalated disc (ID) using transmission electron microscope in atrial tissue.The results showed that there was significant difference in the expression of CVF-I (t=3.827,P<0.01),Cx40 (t=4.21,P<0.01),and groups of the ID that keeping the electrical transmission and atrial electrical coupling synchronization (t=15.116,P<0.001),but no significant difference was found in total IDs (t=0.611,P=0.543) between patients with AF and those with sinus rhythm.The quantitative differences in the tissue remodeling could not explain the ECG characteristics of AF.The number of normal IDs and abnormal distribution are the structural basis to trigger and maintain atrial electrical remodeling,and induce and maintain AF.Such histological reconstruction supports the hypothesis of multi wavelets and can also explain ECG features.

智能网联汽车测试场建设与测试方法浅析

为满足智能网联汽车测试越来越迫切的测试需求,在国内现有的智能网联示范区基础上,概述了智能网联汽车专用测试场地建设方法和智能网联汽车测试方法,着重分析了建设要点,测试工况和实际测试经验总结兼顾,对测试场地的建设提出建议,并在测试方法上提出了V2X的测试框架,对智能网联专用测试场地建设以及测试方法研究具备参考意义。

Estimation of HⅡBubble Size Distribution from 21 cm Power Spectrum with Artificial Neural Networks

The bubble size distribution of ionized hydrogen regions probes information about the morphology of HⅡbubbles during reionization.Conventionally,the HⅡbubble size distribution can be derived from the tomographic imaging data of the redshifted 21 cm signal from the epoch of reionization,which,however,is observationally challenging even for upcoming large radio interferometer arrays.Given that these interferometers promise to measure the 21 cm power spectrum accurately,we propose a new method,which is based on artificial neural networks,to reconstruct the HⅡbubble size distribution from the 21 cm power spectrum.We demonstrate that reconstruction from the 21 cm power spectrum can be almost as accurate as being directly measured from the imaging data with fractional error■10%,even with thermal noise at the sensitivity level of the Square Kilometre Array.Nevertheless,the reconstruction implicitly exploits the modeling in reionization simulations,and hence the recovered HⅡbubble size distribution is not an independent summary statistic from the power spectrum,and should be used only as an indicator for understanding HⅡbubble morphology and its evolution.

乙基纤维素-海藻酸钠/壳聚糖微凝胶的制备及表征

为解决常见微凝胶体系释放过快、缓释效果差的问题,通过乳液法,一步制备了一种新型乙基纤维素包裹的海藻酸钠/壳聚糖微凝胶。对相同水相配比下制备出的水凝胶和微凝胶进行扫描电子显微镜观察、红外光谱、热失重效果、接触角分析和溶胀性能检测,证明了乙基纤维素包覆的海藻酸钠/壳聚糖微凝胶的成功制备。通过对小鼠单核巨噬细胞(RAW264.7)的细胞活性检测发现,微凝胶具有良好的生物相容性能,在100 mg/L的质量浓度下没有明显细胞毒性。利用模型药物甲基蓝考察了不同药物含量、乙基纤维素含量、海藻酸钠和壳聚糖含量、酸钙比(n(GDL)∶n(EDTA-Ca))和钙含量对制备出的微凝胶粒径和包封率的影响,制备出微凝胶的包封率可达到67.1%。最后,对该体系的体外释放效果进行评价,结果显示该体系的持续释放时间长达15 h,且具有一定的pH敏感性。

Long-term outcomes of percutaneous coronary intervention for in-stent chronic total occlusion

Background:The development of the technique has improved the success rate of percutaneous coronary intervention(PCI)for instent chronic total occlusion(IS-CTO).However,long-term outcomes remain unclear.The present study sought to investigate long-term outcomes of PCI for IS-CTO.Methods:A total of 474 IS-CTO patients were enrolled at two cardiac centers from 2015 to 2018 retrospectively.These patients were allocated into either successful or failed IS-CTO PCI groups.The primary endpoint(major adverse cardiac events[MACE])consisted of recurrent angina pectoris(RAP),target-vessel myocardial infarction(MI),heart failure,cardiac death,or ischemia-driven target-vessel revascularization(TVR)at follow-up.Multivariable Cox regression analysis was used to investigate the association between treatment appropriateness and clinical outcomes.Results:A total of 367 patients were successfully treated with IS-CTO PCI while 107 patients had failed recanalization.After a median follow-up of 30 months(interquartile range:17-42 months),no significant difference was observed between the two groups for the following parameters:cardiac death(successful PCIvs.failed PCI:0.9%vs.2.7%;adjusted hazard ratio[HR]:1.442;95%confidence interval[CI]:0.21-9.887;P=0.709),RAP(successful PCIvs.failed PCI:40.8%vs.40.0%;adjusted HR:1.025;95%CI:0.683-1.538;P=0.905),heart failure(successful PCIvs.failed PCI:6.1%vs.2.7%;adjusted HR:0.281;95%CI:0.065-1.206;P=0.088),target-vessel related MI(successful PCIvs.failed PCI:1.5%vs.2.7%;adjusted HR:1.150;95%CI:0.221-5.995;P=0.868),MACE(successful PCIvs.failed PCI:44.2%vs.45.3%;adjusted HR:1.052;95%CI:0.717-1.543;P=0.797).More patients were free of angina in the successful IS-CTO PCI group compared with failed PCI in the first(80.4%vs.60%,P<0.01)and second years(73.3%vs.60.0%,P=0.02)following up.Successful IS-CTO PCI had a lower incidence of MACE in the first and second years(20.2%vs.40.0%,P<0.01;27.9%vs.41.3%,P=0.023)compared with failed PCI.After a median follow-up of 30 months,the reocclusion rate was 28.5%and TVR was 26.1%in the successful IS-CTO PCI group.Receiving>18 months of dual antiplatelet therapy(DAPT)was an independent predictor of decreased risk of TVR(HR:2.682;95%CI:1.295-5.578;P=0.008)or MACE(without TVR)(HR:1.898;95%CI:1.036-3.479;P=0.038)in successful IS-CTO PCI.Conclusions:After a median follow-up of 30 months,the successful IS-CTO PCI group had MACE similar to that of the failed PCI group.However,the successful IS-CTO PCI group had improved angina symptoms and were free from requiring coronary artery bypass grafting in the first or second years.To decrease MACE,DAPT was found to be essential and recommended for at least 18 months for IS-CTO PCI.

Three Cases of COVID-19 Variant Delta With and Without Vaccination——Chengdu City,Sichuan Province,April-May,2021

On April 26,2021,a 33-year-old male Chinese sailor returning from India via Kathmandu,Nepal,tested positive for the coronavirus disease 2019(COVID-19)by Chengdu Customs and was confirmed positive by Chengdu CDC(Case A).On May 2,2021,a housewife in the same flight tested positive for COVID-19 by Pengzhou CDC in Sichuan Province during her quarantine period and was confirmed positive by Chengdu CDC the next day(Case B).

Comprehensive Evaluation of Powdered Chinese Herbal Medicines-An Exemplification of Isatidis Radix

Objective Currently, powdered Chinese herbal medicines （CHMs） were mainly evaluated through physical property, chemical dissolution, and bioactivity independently. It could not reflect the quality comprehensively. This paper was to explore and establish a comprehensive evaluation method for powdered CHMs. Methods Isatidis Radixwas chosen as an exemple. Firstly, powdered Isatidis Radixin different particle size was prepared. Then, their physical properties were characterized. The dissolution of index component epigoitrin was determined, and their antiviral activities were evaluated by neuraminidase-based bioassay. Results As the particle size decreased, powder distribution tended to be uniform, and the dissolution of epigoitrin increased, antiviral activity enhanced. According to cluster analysis of above results, the sequence of evaluation consequence was ultrafine powder S2 （D90：32.80± 0.29） 〉 ultrafine powder S1 （D90：52.08 ± 0.53） 〉 fine powder SO （D90：118.16± 0.76） （from the superior to the inferior）. Conclusion Overall, the comprehensive evaluation for powdered CHMs based on the physical characterization, chemical dissolution, and bioassay could not only be used to evaluate powdered herbs, but also guide the screening and optimization of the particle size of powder.

A novel adaptive heuristic dynamic programming-based algorithm for aircraft confrontation games

Intelligent confrontation has become a vital technology for future air combats.Confrontation games between a penetrating aircraft and an intercepting aircraft are essential for modern air combats.In addition,the perfor-mance indexes of both the interceptor and penetrator must be considered.Traditional methods only solve one side’s guidance problem without considering the intelligence of the opponent.In this paper,an adaptive heuristic dynamic programming-based algorithm is proposed for aircraft confrontation games.This algorithm constructs a heuristic dynamic programming model for both confrontation aircraft and then updates the critical and ac-tion network parameters using the dynamic confrontation state information.Numerical simulations indicate that the proposed algorithm can optimize the guidance law for both the interceptor and penetrator and is therefore superior to traditional proportional navigation methods.

Two Cases of COVID-19 with Persistently Positive SARS-CoV-2- Specific IgM During One-Year Follow-Up-Sichuan Province,China,February 2021

On January 22,2020,a 41-year-old male(Patient A)developed a fever with a maximum temperature of 38°C after returning to Chengdu City from Wuhan City.He was admitted to the Public Health Clinical Center of Chengdu on January 26,2020,after being confirmed to be positive for coronavirus disease 2019(COVID-19)by Chengdu CDC.Chest computed tomography(CT)revealed multiple plaque-like,ground-glass shadows in the upper,middle,and lower lobes of the right lung and upper and lower lobes of the left lung,as well as a small amount of pericardial effusion.