Structured Compressive Sensing-Based Spatio-Temporal Joint Channel Estimation for FDD Massive MIMO

Zhen Gao,Linglong Dai,Wei Dai,Byonghyo Shim,Zhaocheng Wang IEEE 2016 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.64 No.2

<P>Massive MIMO is a promising technique for future 5G communications due to its high spectrum and energy efficiency. To realize its potential performance gain, accurate channel estimation is essential. However, due to massive number of antennas at the base station (BS), the pilot overhead required by conventional channel estimation schemes will be unaffordable, especially for frequency division duplex (FDD) massive MIMO. To overcome this problem, we propose a structured compressive sensing (SCS)-based spatio-temporal joint channel estimation scheme to reduce the required pilot overhead, whereby the spatio-temporal common sparsity of delay-domain MIMO channels is leveraged. Particularly, we first propose the nonorthogonal pilots at the BS under the framework of CS theory to reduce the required pilot overhead. Then, an adaptive structured subspace pursuit (ASSP) algorithm at the user is proposed to jointly estimate channels associated with multiple OFDM symbols from the limited number of pilots, whereby the spatio-temporal common sparsity of MIMO channels is exploited to improve the channel estimation accuracy. Moreover, by exploiting the temporal channel correlation, we propose a space-time adaptive pilot scheme to further reduce the pilot overhead. Additionally, we discuss the proposed channel estimation scheme in multicell scenario. Simulation results demonstrate that the proposed scheme can accurately estimate channels with the reduced pilot overhead, and it is capable of approaching the optimal oracle least squares estimator.</P>

旅游區域合作發展問題硏究

대언진 ( Yan Zhen Dai ),임수령 ( Xiu Ling Lin ) 한국관광산업학회 2004 국제관광학술대회 Vol.- No.-

Adsorption and separation of lignin-based aromatic aldehydes using macroporous resins

Zhen Wu,Lei Hu,Ning Xu,Benlin Dai,Jiaxing Xu 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.7

Lignin-based aromatic aldehydes (p-hydroxybenzaldehyde, vanillaldehyde and syringaldehyde) have wide applications in flavoring. However, their separation using chromatographic methods has not been explored. We studied the adsorption and desorption behaviors of aromatic aldehydes on macroporous resins and four macroporous resins X-5, CAD-40, AB-8 and D101 were screened for separation of aromatic aldehydes. The results demonstrated that X-5 showed the highest adsorption and desorption capacities. The adsorption capacities for p-hydroxybenzaldehyde, vanillaldehyde and syringaldehyde on X-5 were 33.5mg/g, 46.6mg/g and 47.0mg/g at 20 oC, respectively, higher than that of CAD-40, AB-8 and D101. Adsorption isotherms of aromatic aldehydes on X-5 were confirmed to fit to Freundlich equation which was calculated by lnQe=0.6933lnCe+6.788, lnQe=0.7031lnCe+7.7358 and lnQe=0.7107lnCe+ 8.2412 for p-hydroxybenzaldehyde, vanillaldehyde and syringaldehyde, respectively. The results of dynamic adsorption and desorption experiments demonstrated that 50% (v/v) ethanol solution was an effective elution solvent for aromatic aldehydes. The maximum concentration of the three kinds of aromatic aldehydes in eluent reached 3.74 g/L, 5.44 g/L and 7.03 g/L, which indicated that the elution process was also an effective enrichment process for sorbate.

The East Asian Summer Monsoon Response to Global Warming in a High Resolution Coupled Model: Mean and Extremes

Zhen Liu,이순선,Arjun Babu Nellikkattil,이준이,Lan Dai,하경자 한국기상학회 2023 Asia-Pacific Journal of Atmospheric Sciences Vol.59 No.1

Current climate models still have considerable biases in the simulation of the East Asian summer monsoon (EASM), which in turn reduces their reliability of monsoon projections under global warming. We hypothesize that a higher-resolution coupled climate model with atmospheric and oceanic components at horizontal resolutions of 0.25° and 0.1°, respectively, will better capture regional details and extremes of the EASM. Present-day (PD), 2 × CO2 and 4 × CO2 simulations are conducted with the Community Earth System Model (CESM1.2.2) to evaluate PD simulation performance and quantify future changes. Indeed, our PD simulation well reproduces the climatological seasonal mean and intra-seasonal northward advancement of the monsoon rainband, as well as climate extremes. Compared with the PD simulation, the perturbed CO2 experiments show an intensified EASM response to CO2- induced warming. We find that the precipitation increases of the Meiyu-Baiu-Changma band are caused by comparable contributions from the dynamical and thermodynamical components in 2 × CO2, while they are more driven by the thermodynamical component in 4 × CO2 due to stronger upper atmospheric stability. The regional changes in the probability distribution of the temperature show that extreme temperatures warm faster than the most often temperatures, increasing the skewness. Fitting extreme precipitation values with a generalized Pareto distribution model reveals that they increase significantly in 4 × CO2. Changes of temperature extremes scale with the CO2 concentrations over the monsoon domain but not for precipitation extreme changes. The 99th percentile of precipitation over the monsoon region increases at a super Clausius-Clapeyron rate, ~ 8% K– 1, which is mainly caused by increased moisture transport through anomalous southerly winds.

RVA Property analysis of rice varieties under different ecological condition of Yunnan Plateau

Zhen-Hua Zhu,Ki-Young Kim,Bo-Kyeong Kim,Lu-Yuan Dai,Jae-Kwon Ko 한국작물학회 2008 한국작물학회 학술발표대회 논문집 Vol.2008 No.10

Starch RVA profile parameters serve as important indices in the estimation of rice cooking and eating quality. Four cold- tolerant and five cold-sensitive japonica rice varieties grown at 3 different altitudes in Yunnan plateau were used in this experiments. RVA parameters including peak viscosity(PKV), hot viscosity(HTV), final viscosity(FLV), breakdown viscosity(BDV), setback viscosity(SBV) and pasting temperature(PaT) were investigated. SBV and PaT of cold tolerant varieties and PKV, BDV and SBV of cold-sensitive varieties were significantly influenced by environments. The variances of RVA parameters were affected by genotype×environment interactions in cold tolerant and sensitive varieties. The coefficients of variation of RVA parameters except for SBV in cold tolerant varieties were lower than those in cold sensitive varieties. HTV, FLV and SBV of cold tolerant varieties were significantly lower, while PKV, BDV and PaT were significantly higher than those of cold sensitive varieties. With altitude increasing, SBV and PaT of cold sensitive varieties increased significantly, whereas PKV, HTV, FLV and BDV decreased significantly. However, PKV, BDV and PaT of cold tolerant varieties gradually increased while HTV, FLV and SBV increased and then gradually decreased with altitude rising. These results suggested that cooking and eating quality would be improved by improving cold tolerance of rice varieties in breeding program.

In Vitro Development and Transfer of Resistance to Chlortetracycline in Bacillus subtilis

Menghong Dai,Junjie Lu,Yulian Wang,Zhenli Liu,Zonghui Yuan 한국미생물학회 2012 The journal of microbiology Vol.50 No.5

The present criteria and rules controlling the approval of the use of probiotics are limited to antibiotic resistance patterns and the presence of antibiotic resistance genes in bacteria. There is little information available in the literature regarding the risk of the usage of probiotics in the presence of antibiotic pressure. In this study we investigated the development and transfer of antibiotic resistance in Bacillus subtilis selected in vitro by chlortetracycline in a stepwise manner. Bacillus subtilis was exposed to increasing concentrations of chlortetracyclineto induce in vitro resistance to chlortetracycline, and the minimal inhibitory concentrations were determinedfor the mutants. Resistant B. subtilis were conjugated with Escherichia coli NK5449 and Enterococcus faecalis JH2-2 using the filter mating. Three B. subtilis tetracycline resistant mutants (namely, BS-1, BS-2, and BS-3)were derived in vitro. A tetracycline resistant gene, tet (K),was found in the plasmids of BS-1 and BS-2. Three conjugates (BS-1N, BS-2N, and BS-3N) were obtained when the resistant B. subtilis was conjugated with E. coli NK5449. The conjugation frequencies for the BS-1N, BS-2N, and BS-3N conjugates were 4.57×10-7, 1.4×10-7, and 1.3×10-8,respectively. The tet(K) gene was found only in the plasmids of BS-1N. These results indicate that long-term use of probiotics under antibiotic selection pressure could cause antibiotic resistance, and the resistance gene could be transferred to other bacteria. The risk arising from the use of probiotics under antibiotic pressure should be considered in the criteria and rules for the safety assessment of probiotics.

Long Noncoding RNA Expression Profiling During the Neuronal Differentiation of Glial Precursor Cells from Rat Dorsal Root Ganglia

Yunfei Dai,Wei Ma,Tong Zhang,Jinwei Yang,Chenghao Zang,Kuangpin Liu,Xianbin Wang,Jiawei Wang,Zhen Wu,Xingkui Zhang,Chunyan Li,Junjun Li,Xiangpeng Wang,Jianhui Guo,Liyan Li 한국생물공학회 2020 Biotechnology and Bioprocess Engineering Vol.25 No.3

Long noncoding RNAs (lncRNAs) play important roles in the process of cell fate determination. However, their function and expression profiles have not yet been systematically investigated during the transdifferentiation of glial precursor cells derived from dorsal root ganglia (DRG) in the peripheral nervous system. Our results demonstrated significant differences in gene architecture and expression among the three transcript types (lncRNA, mRNA, and TUCP). Distinct differences in transcript length, exon number, and ORF length were identified between lncRNAs and mRNAs after comparative analysis of their structure and sequence conservation. We found that the upregulated lncRNAs outnumbered the downregulated lncRNAs in glial precursor cells cultured with proBDNF antiserum compared with the levels in glial precursor cells cultured without proBDNF antiserum. By a series of GO and KEGG analyses, we found that the effects of some lncRNAs on their target genes in cis were related to nerve growth factor-induced cell cycle, cell phenotype change, and neuronal differentiation. The qRT-PCR verification results of lncRNAs ENSRNOT00000091991, ENSRNOT00000087717, and LNC_000429 were mostly consistent with the sequencing results. The candidate lncRNAs may be associated with the neuronal transdifferentiation of glial precursor cells. Our study provides the first evidence for a remarkably diverse pattern of lncRNA expression during neuronal differentiation of glial precursor cells from rat DRG, and also provides a resource for lncRNA studies in the field of cell differentiation.

Modeling on Thermal Efficiency and Nox Emission of Alkali Recovery Furnace Depending on Oxygen Content of Flue Gas

Yan Li,Zhen Hu,Ceng-fei,Yun Qing-yu Dai 한국펄프·종이공학회 2020 펄프.종이기술 Vol.52 No.5

Integration Sites and Genotype Distributions of Human Papillomavirus in Cervical Intraepithelial Neoplasia

Wang, Li,Dai, Shu-Zhen,Chu, Hui-Jun,Cui, Hong-Fei,Xu, Xiao-Yan Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.6

Objectives: To analyse HPV integration prevalence and genotype distributions in cervical intraepithelial neoplasia (CIN) in east part of China, furthermore to assess preferential sites for common HPV integrations and provide baseline information for cervical abnormality screening and prevention. Methods: Integration of HPV in 113 paraffin-embedded cervical intraepithelial neoplasia samples was assessed using Gencap technology in Key Laboratory of Biotechnologies in BGI-Shenzhen. Results: 64 samples were HPV-integrated and as the cervical lesions increased, the integration rate became higher significantly (P=0.002). Fifteen different HPV genotypes were detected, 14 high-risk (16, 18, 31, 33, 51, 52, 56, 58, 66, 68) and 1 low-risk (11). The most common genotypes were HPV-16, 58, 33, 52, 66, and 56. Thirteen patients had co-integration involving mainly HPV-16 and 58. The frequency of HPV gene disruption was higher in L1 and E1 genes than in other regions of the viral genomes. Conclusion: Some 56.6% of CIN lesions in Qingdao had HPV integrations, and 67.2% of HPV-integrated patients were HPV-16 and 58, more prone to be integrated in younger patients below 45 years old. There exist preferential sites for HPV-16 and HPV-58 integration, and they are more likely to be disrupted in the L1 and E1 loci.

Rho-GTPase Effector ROCK Phosphorylates Cofilin in Actin-Meditated Cytokinesis During Mouse Oocyte Meiosis

Duan, Xing,Jun-Liu,Dai, Xiao-Xin,Liu, Hong-Lin,Cui, Xiang-Shun,Kim, Nam-Hyung,Wang, Zhen-Bo,Qiang-Wang,Sun, Shao-Chen Society for the Study of Reproduction [etc.] 2014 BIOLOGY OF REPRODUCTION Vol.90 No.2

During oocyte meiosis, a spindle forms in the central cytoplasm and migrates to the cortex. Subsequently, the oocyte extrudes a small body and forms a highly polarized egg; this process is regulated primarily by actin. ROCK is a Rho-GTPase effector that is involved in various cellular functions, such as stress fiber formation, cell migration, tumor cell invasion, and cell motility. In this study, we investigated possible roles for ROCK in mouse oocyte meiosis. ROCK was localized around spindles after germinal vesicle breakdown and was colocalized with cytoplasmic actin and mitochondria. Disrupting ROCK activity by RNAi or an inhibitor resulted in cell cycle progression and polar body extrusion failure. Time-lapse microscopy showed that this may have been due to spindle migration and cytokinesis defects, as chromosomes segregated but failed to extrude a polar body and then realigned. Actin expression at oocyte membranes and in cytoplasm was significantly decreased after these treatments. Actin caps were also disrupted, which was confirmed by a failure to form cortical granule-free domains. The mitochondrial distribution was also disrupted, which indicated that mitochondria were involved in the ROCK-mediated actin assembly. In addition, the phosphorylation levels of Cofilin, a downstream molecule of ROCK, decreased after disrupting ROCK activity. Thus, our results indicated that a ROCK-Cofilinactin pathway regulated meiotic spindle migration and cytokinesis during mouse oocyte maturation.