Low complexity method for spreading sequence estimation of DSSS signal in non-cooperative communication systems

It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum （DSSS） signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detection statistics are proposed to implement the synchronization and spreading sequence estimation procedure. The proposed algorithm also has a low computational complexity with only linear additions and modifications. Theoretical analysis and simulation results show that the algorithm performs quite well in low SNR environment, and is much better than all the existing typical algorithms with a comprehensive consideration both in performance and computational complexity.

Evaluating the potential of(epi)genotype‑by‑low pass nanopore sequencing in dairy cattle:a study on direct genomic value and methylation analysis

Background Genotype-by-sequencing has been proposed as an alternative to SNP genotyping arrays in genomic selection to obtain a high density of markers along the genome.It requires a low sequencing depth to be cost effective,which may increase the error at the genotype assigment.Third generation nanopore sequencing technology offers low cost sequencing and the possibility to detect genome methylation,which provides added value to genotype-by-sequencing.The aim of this study was to evaluate the performance of genotype-by-low pass nanopore sequencing for estimating the direct genomic value in dairy cattle,and the possibility to obtain methylation marks simultaneously.Results Latest nanopore chemistry(LSK14 and Q20)achieved a modal base calling accuracy of 99.55%,whereas previous kit(LSK109)achieved slightly lower accuracy(99.1%).The direct genomic value accuracy from genotype-by-low pass sequencing ranged between 0.79 and 0.99,depending on the trait(milk,fat or protein yield),with a sequencing depth as low as 2×and using the latest chemistry(LSK114).Lower sequencing depth led to biased estimates,yet with high rank correlations.The LSK109 and Q20 achieved lower accuracies(0.57-0.93).More than one million high reliable methylated sites were obtained,even at low sequencing depth,located mainly in distal intergenic(87%)and promoter(5%)regions.Conclusions This study showed that the latest nanopore technology in useful in a LowPass sequencing framework to estimate direct genomic values with high reliability.It may provide advantages in populations with no available SNP chip,or when a large density of markers with a wide range of allele frequencies is needed.In addition,low pass sequencing provided nucleotide methylation status of>1 million nucleotides at≥10×,which is an added value for epigenetic studies.

Low-complexity PTS scheme based on phase factor sequences optimization

In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.

Design Optimization of CFRP Stacking Sequence Using a Multi-Island Genetic Algorithms Under Low-velocity Impact Loads

A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact（CAI） tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.

Applied Sequence Stratigraphy in Nonmarine Basin of China

This paper presents a preliminary summary of the applied sequence stratigraphy in nonmarine basins in China. The geological and geophysical data show that the nonmarine sequences mainly resulted from both allocyclic and autocyclic processes where the most important factors were isolated tectonics and climate. However, the environmental factor should have been crucial. The depositional base level served as the sea level in the marine environment, while the water table, lake level and fluvial equilibrium were profiled in a terrigenous environment. This accommodation varied periodically with the base level, resulting in the formation of a series of depositional sequences in terms of genesis and space. Basically, the base level of the inner continent was not affected by the changes in the relative sea level. But there would have been some relations between the changes in the relative sea level and that in the continental base level during eustacy flooding. However, a small time lag existed between the changes in the marine basin and the inner continent basin, The lake basin is smaller than the marine basin, but its velocity of sediment supply is greater than that of the marine basin. Therefore, the number of nonmarine sequences is greater than that of marine ones in the same period. It is important to recognize the system tracts for the study of high-precision or high-resolution sequence stratigraphy, especially to analyze the low-stand systems tract with its depositional system. The sequence boundary is genetically characterized by subaerial exposure, stratigraphic truncation and subaqueous erosion. The deposition analysis of Zhanhua depression reveals 5 sequence architectures: alluvial-fluvial/lacustrine architecture, transitional architecture formed between haline (mesohaline) lake and fresh lake, marine duration-deep lacustrine architecture, half deep lacustrine-ramp architecture and fluvial-alluvial plain architecture. During the major development of the nonmarine basin, the step-faulting breaks controlled the depositional system. Usually, the low-stand complex fan, prograding wedge and high-stand turbidity fan were close to the third stepping break. In the low-stand period, the sediments went around the incised valleys which then were filled with sand bar near the second stepping break. At the first stepping break the sediments were bypassed step by step or the alluvial fan was deposited with forced regressions in the low-stand time. The low-stand wedge may serve as favorable subtle or complex traps at the basin floor fan. The economic effectiveness is measured with the borehole in Bohai Bay basin.

Novel Frequency Hopping Sequences Generator Based on AES Algorithm

A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorithm have good performance in uniformity, correlation, complexity and security.A high-speed, low-power and low-cost ASIC of FH sequences generator is implemented by optimizing the structure of S-Box and MixColumns of AES algorithm, proposing a hierarchical power management strategy, and applying the dynamic clock gating technology based on finite state machine and clock gating.SMIC 0.18 μm standard CMOS technology shows that the scale of ASIC is only about 10.68 kgate, power consumption is 33.8 μW/MHz, and the maximum hop-rate is 1 098 901 hop/s.This design is suitable for portable FH communication system for its advantages in high-security and hop-rate, low-power and low-cost.The proposed FH sequences generator has been employed in Bluetooth SoC design.

Relationship between the earthquake sequences of Tangshan and Xingtai and the three dimensional velocity structure──Discussion on predicting strong earthquakes of swarm-type

In this paper, based on the results of tomographic image of Tangshan and Xingtai areas, the relations between thecharacteristics of the two strong earthquake sequences and their three-dimensional velocity structures are studied.The research results indicate that:① Mosaic distribution of low-velocity bodies and high-velocity bodies, especially the existence of high-velocity bodies with large size in crust are the common basis of development of thetwo earthquake sequences. ② Scale, depth, and heterogeneity of high-velocity and low-velocity bodies are theimportant factors to effect the characteristic of earthquake sequences. ③ The depth of the high-velocity body inTangshan area is less than that in Xingtai area, which is the principal reason why the dominant focal depth and thebiggest focal depth of Tangshan earthquake sequence are less than Xingtai's. ④ The depth of the high-velocitybodies in Ninghe area is more than that in Tangshan-Luanxian area, which lead to the biggest magnitude and epicentral intensity are lower. These results could be helpful for predicting the main shock of strong swarm-typeearthquakes and later strong aftershocks.

Repetitive sequence analysis and karyotyping reveal different genome evolution and speciation of diploid and tetraploid Tripsacum dactyloides

In the subtribe Maydeae, Tripsacum and Zea are closely related genera. Tripsacum is a horticultural crop widely used as pasture forage. Previous studies suggested that Tripsacum might play an important role in maize origin and evolution. However, our understanding of the genomics and the evolution of Tripsacum remains limited. In this study, two diploids,T. dactyloides var. meridionale(2n = 36, MR) and T. dactyloides(2n = 36, DD), and one tetraploid,T. dactyloides(2n = 72, DL) were sequenced by low-coverage genome sequencing followed by graph-based cluster analysis. The results showed that 63.23%, 59.20%, and 61.57% of the respective genome of MR, DD, and DL were repetitive DNA sequence. The proportions of different repetitive sequences varied greatly among the three species. Fluorescence in situ hybridization(FISH) analysis of mitotic metaphase chromosomes with satellite repeats as the probes showed that the FISH signal patterns of DL were more similar to that of DD than to that of MR. Comparative analysis of the repeats also showed that DL shared more common repeat families with DD than with MR. Phylogenetic analysis of internal transcribed spacer region sequences further supported the evolutionary relationship among the three species. Repetitive sequences comparison showed that Tripsacum shared more repeat families with Zea than with Coix and Sorghum. Our study sheds new light on the genomics of Tripsacum and differential speciation in the Poaceae family.

高通量测序技术在低频突变检测中的应用

体细胞突变的累积与衰老、肿瘤及多种疾病的发生密切相关。在正常组织细胞中,基因组中自发突变和诱发突变的变异等位基因频率极低,对这类低频突变的检测一直面临挑战。第二代和第三代高通量测序(next-generation sequencing,NGS)技术的出现,可以实现任意物种全基因组上变异的直接检测,克服传统突变检测技术的诸多局限性。但是常规NGS由于测序错误率较高从而限制了其在低频突变检测上的应用,基于分子一致性测序策略进行错误矫正的高准确性NGS测序技术作为有效的低频突变检测工具,有望在环境诱变剂的评价与研究、细胞与基因治疗药物风险评估、人群健康风险监测和生命科学基础研究领域发挥重要作用。本文对比经典突变检测方法,对基于NGS的低频突变检测技术研究进展进行综述,并对应用前景进行展望,以期为该技术的进一步开发、研究和在相关领域的应用提供参考。

以生长发育迟缓为表现的1例O’Donnell-Luria-Rodan综合征临床与遗传学特征分析

O’Donnell-Luria-Rodan(ODLURO)综合征是KMT2E(lysine methyltransferase 2E)基因突变引起的常染色体显性遗传病。中南大学湘雅三医院收治1例表现为生长发育迟缓、智力低下、特殊面容的12岁9个月男性患儿,采集患者外周血,提取DNA进行基因检测,发现患儿染色体核型为46XY,全外显子组测序及低深度全基因组测序技术(low-coverage massively parallel copy number variation sequencing,CNV-seq)分析显示患儿在染色体7q 22.3区域存在506 kb的杂合性缺失,缺失区域包含KMT2E在内的6个基因,诊断为ODLURO综合征。其父母、弟弟临床表型及基因检测均无异常,提示该缺失为新发突变。此病例的临床和遗传特征有助于提高临床医师对ODLURO综合征的认识。

柔性低频输电系统的主变稳态负序差动保护

为了解决常规纵差保护难以适用于低频系统的问题,通过分析低频系统的序分量抑制策略,并根据低频系统故障进入稳态后单侧有负序注入的特征,提出一种基于稳态负序分量的主变差动保护方法。为防止该差动保护在区外故障时因电流互感器饱和出现误动,通过对比分析三类制动电流计算方式的制动性能,得到了差动保护的制动方程和制动系数。为解决励磁涌流、电流互感器断线可能导致误动的问题,提出了相电压突变量的差动保护开放条件。仿真分析表明,该方法能够灵敏反映区内金属性故障及轻微故障,在区外故障伴随电流互感器饱和时有可靠的制动裕度。

基于等效序阻抗差异特征的低频输电线路差动保护优化方案

低频输电线路故障时,两侧短路电流均由模块化多电平矩阵变换器提供,两侧短路电流相角均受控且幅值相当,导致差动保护灵敏度严重下降。分析了低频输电系统定电压控制侧和功率控制侧的等效正、负序阻抗特征,指出因控制策略不同,系统故障时两侧等效正、负序阻抗特征存在明显差异。分析了低频输电线路区内和区外故障两侧保护装置测量到的等效序阻抗之间的差异性和相似性,基于此特征构建了两侧等效序阻抗差异指标,提出了基于等效序阻抗差异指标的差动保护制动系数优化方法。仿真结果表明,所提方案能够显著提升低频输电线路区内故障时差动保护的动作速度和动作灵敏性。

脊柱-骨盆矢状位参数与腰椎退行性疾病术后持续性下腰痛的关系

目的 分析脊柱-骨盆矢状位序列参数变化与腰椎退行性疾病(degenerative lumbar disease,DLD)患者术后持续性下腰痛的关系。方法 选取天津市人民医院2019年6月至2022年6月行单节段腰椎融合内固定术治疗的86例DLD患者,根据术后是否发生持续性下腰痛分为腰痛组和非腰痛组。腰痛组34例,男10例,女24例;年龄32~77岁,平均(59.36±8.65)岁。非腰痛组52例,男21例,女31例;年龄30~78岁,平均(56.81±8.03)岁。比较两组患者一般资料、手术前后疼痛视觉模拟评分(visual analogue score,VAS)、日本骨科协会(Japanese orthopaedic association,JOA)腰椎功能评分及脊柱-骨盆矢状位序列参数[腰椎前凸角(lumbar lordosis,LL)、骨盆入射角(pelvic incidence,PI)、骨盆倾斜角(pelvic tilt,PT)、骶骨倾斜角(sacral slope,SS)]。分析术后持续性下腰痛发生的影响因素,分析手术前后脊柱-骨盆矢状位序列参数变化值与VAS、JOA评分变化值的相关性,分析手术前后脊柱-骨盆矢状位序列参数变化值及相关影响因素预测术后发生持续性下腰痛的价值。结果 腰痛组骨质疏松、术中骨性终板损伤发生率(47.06%、23.53%)高于非腰痛组(15.38%、1.92%);腰痛组术后3个月VAS、PT高于非腰痛组,JOA评分、LL、SS低于非腰痛组,ΔVAS、ΔJOA、ΔLL、ΔPI、ΔPT、ΔSS小于非腰痛组(P<0.05);DLD患者ΔLL、ΔPT、ΔSS均与ΔVAS、ΔJOA间存在正相关关系(P<0.05),ΔPI与ΔVAS、ΔJOA间无明显相关性(P>0.05);骨质疏松、术中骨性终板损伤、ΔLL、ΔPT、ΔSS均为DLD患者术后发生持续性下腰痛的影响因素(P<0.05);ΔLL、ΔPT、ΔSS预测DLD患者术后发生持续性下腰痛的曲线下面积(area under the curve,AUC)分别为0.776、0.825、0.731;与ΔLL、ΔPT、ΔSS单独预测比较,ΔLL、ΔPT、ΔSS联合预测的AUC(0.939)明显增大,净重新分类指数、综合判别改善指数均>0(P<0.05)。结论 脊柱-骨盆矢状位序列参数变化与DLD患者腰椎术后持续性下腰痛的发生有关,且在预测术后发生持续性下腰痛方面具有良好应用价值。

基于RNA-Seq筛选高粱低氮胁迫相关候选基因

研究低氮胁迫条件下不同高粱材料间的基因差异表达,为耐低氮型高粱品种选育和耐低氮胁迫的分子机制探究提供参考。选取2个耐低氮型高粱(BSX44和BTx378)为试验材料,设置正常和低氮胁迫2个处理,利用RNA-Seq技术对高粱苗期、抽穗期和开花期的基因表达进行分析,通过生物信息学对差异基因的生物学功能和代谢途径进行研究,筛选可能参与低氮调控的基因,了解氮高效基因型在氮素吸收利用过程中可能的分子途径。结果表明,在正常和低氮胁迫下,BTx378和BSX44在苗期分别筛选出937个和787个差异表达基因,抽穗期分别筛选出1305个和935个差异表达基因,开花期分别筛选出1402个和963个差异表达基因。对3个时期的差异表达基因进行鉴定,发现在苗期、抽穗期和开花期分别有246、371和306个基因在2个耐低氮高粱品种中共同差异表达,有28个基因在2个耐低氮品种的不同生育时期均差异表达,其中有5个基因上调表达,23个基因下调表达;对共同差异表达基因的KEGG相关代谢通路富集分析,发现主要集中在氮代谢、丙氨酸,天冬氨酸和谷氨酸代谢、甘油磷脂代谢、氨基酸的生物合成等途径,表明耐低氮型高粱可能通过这些途径相关基因的表达影响其对低氮胁迫的耐受性。

基于低频暂态零序电流畸变率的灵活接地系统高阻接地保护

灵活接地系统中,基于稳态故障特征构成的单相接地保护普遍存在耐过渡电阻能力低的问题,并联小电阻投入后该问题进一步突出。文中研究了并联小电阻投入后故障线路与非故障线路低频暂态零序电流中暂态直流分量比值关系,发现暂态直流分量比值仅与对地电容有关。分析了故障线路与非故障线路低频暂态零序电流畸变率之间比值关系,进一步提出了一种基于低频暂态零序电流畸变率的灵活接地系统单相高阻接地故障选线方法。通过比较特定时间窗口内各馈线低频暂态零序电流畸变率的大小实现故障选线,并可准确区分母线故障与出线故障。该方法能够避免零序电压互感器断线与零序电流互感器极性反接的影响,且受故障距离影响小。同时,该方法采用暂态故障特征构成选线判据,有利于克服并联小电阻投入后稳态故障分量微弱的问题,对互感器精度要求不高。最后,通过实时数字仿真和实验平台分别验证了所述方法的准确性和有效性。

光储联合发电系统不对称故障穿越控制策略

针对电网不对称故障下光伏发电系统输出功率与直流侧电压二倍频波动问题,提出了一种光储联合发电系统低电压穿越控制策略。在低电压穿越期间,充分利用光伏并网逆变器和储能变流器容量向电网输送有功和无功功率;在此基础上令储能变流器采取基于负序虚拟电导的负序电压补偿控制策略;同时,分析了单台以及多台储能变流器参与负序电压补偿的原理,并对负序虚拟电导进行了自适应优化设计。仿真结果表明,所提控制策略能够有效削弱光伏发电系统输出功率与直流侧电压的二倍频波动。

基于低压侧负序量特征的小电流系统单相接地故障检测方法

随着台区智能终端量测技术的逐步成熟,实现低压侧全息感知的同时,具备对上级中压配网的多点监测能力。提出基于低压侧负序量特征的小电流系统单相接地故障检测方法。分析了中压侧发生单相接地故障后低压侧负序量的变化规律;利用负序电流大小区分故障线路和非故障线路;提出通过负序电压与正序电压的比值系数,多点协同计算对比判断故障点区段位置,且考虑了低压侧不平衡负荷,以及故障点位于线路一端的特殊情况。通过MATLAB软件和动模实验对中低压联合配电系统的仿真计算,验证了所提方法具有良好的鲁棒性和准确性。通过智能配变终端监测上级中压配网负序量信息,实现小电流接地系统故障检测,具有实际应用和推广价值。

高寒地区菊芋青贮物料耐低温乳酸菌的筛选与鉴定

为筛选可提升高寒地区菊芋(Helianthus tuberosus)青贮发酵品质的耐低温乳酸菌,本研究以‘青芋2号’菊芋青贮物料为材料,利用平板培养法分离乳酸菌株,分析菌株生理生化特性,并通过16S rRNA测序进行菌株种属鉴定。结果表明,菊芋青贮物料中共分离得到34株乳酸菌株,经低温及生理生化筛选获得13株耐低温乳酸菌株,包括11株同型发酵乳酸菌和2株异型发酵乳酸菌,其耐酸性和耐盐性均较强;经产酸和生长能力对比,GN02菌株生长最快(OD=2.63),GN10菌株具有更强的产酸能力(pH=3.59),XN25菌株兼具较强的生长和产酸能力;16S rRNA测序鉴定出9株植物乳杆菌(Lactiplantibacillus plantarum)、1株戊糖乳杆菌(Lactiplantibacillus pentosus)、1株棒状乳杆菌(Lactiplantibacillus coryniformis)、1株短乳杆菌(Lactiplantibacillus brevis)及1株无法鉴定。本研究筛选出适合高寒地区菊芋青贮发酵的耐低温植物乳杆菌、戊糖乳杆菌、短乳杆菌各1株。

低温环境下野外自然好氧堆肥理化特征及微生物群落结构变化

[目的]研究低温环境下野外自然好氧堆肥理化特征及微生物群落结构变化,实现低温季节养殖废弃物的资源化利用。[方法]以猪粪和稻壳为原料在低温环境下进行自然好氧堆肥处理,对堆肥过程中温度、pH、含水率、NH_(4)^(+)-N、NO_(3)^(-)-N和种子发芽指数(GI)进行分析,选取细菌16S rDNA V3~V4区和真菌ITS序列进行高通量测序,比较好氧堆肥过程中不同阶段微生物群落多样性及组成差异。[结果]当环境温度为-6.7~6.4℃时,整个堆肥过程高温阶段持续11 d,经过38 d的好氧堆肥处理,堆体含水率、pH、NH_(4)^(+)-N、NO_(3)^(-)-N等指标均趋于稳定,堆肥结束时GI达到了122.12%,表明堆肥产品完全腐熟。低温条件下堆肥不同阶段样本微生物群落分析表明,Acinetobacter是堆肥初期和升温阶段优势细菌属,而Pseudofulvimonas和Ensifer在堆肥高温阶段丰度最高,Parapedobacter为堆肥末期优势细菌属。Ascobolus是堆肥初期优势真菌属,而Mycothermus为好氧堆肥升温、高温和腐熟阶段的优势菌群。细菌群落功能预测结果表明,氨基酸转运和代谢、碳水化合物运输和代谢等是堆肥过程中细菌的主要代谢功能。理化指标与微生物多样性相关性分析表明,堆肥过程中pH与属水平上丰度较高的微生物相关性强,含水率、温度、NH_(4)^(+)-N和发芽指数次之。[结论]低温条件下野外自然好氧堆肥可顺利进行并完全腐熟,这为低温环境下野外自然好氧堆肥提供了依据。

两级变幅应变疲劳本征损伤耗散寿命预测模型研究

在变幅低周疲劳载荷条件下,材料的疲劳损伤累积过程中呈现出了显著的载荷顺序效应.这种现象复杂化了变幅疲劳寿命的预测,因此,如何更精确地预测变幅低周载荷下的疲劳寿命,已经成为了一个亟待解决的问题.针对变幅低周疲劳载荷下损伤累积表现的载荷顺序效应,考虑到本征损伤耗散与疲劳损伤构成一一映射,且刻画低周疲劳破坏的热力学本质,基于连续介质损伤力学及其不可逆热力学框架,推导本征损伤耗散功演化模型D型描述并以等同本征损伤耗散功作为损伤转换条件,建立了一种考虑载荷顺序效应的变幅低周疲劳寿命预测模型.为了验证新模型的有效性和先进性,进行了P355NL1结构钢和Ti-6Al-4V钛合金在两级变幅载荷下的单轴低周疲劳实验验证,并与Manson模型、Kwofie模型和Peng模型进行了比较分析.研究结果表明,新建模型的预测效果都在1.5倍的误差范围内,与实验结果相当吻合,且优于现有的预测模型.运用本征损伤耗散理论开展变幅疲劳寿命预测,为金属材料变幅疲劳寿命预测提供了新思路.