Fast parallel factor decomposition technique for coherently distributed source localization

This paper links parallel factor（PARAFAC） analysis to the problem of nominal direction-of-arrival（DOA） estimation for coherently distributed（CD） sources and proposes a fast PARAFACbased algorithm by establishing the trilinear PARAFAC model.Relying on the uniqueness of the low-rank three-way array decomposition and the trilinear alternating least squares regression, the proposed algorithm achieves nominal DOA estimation and outperforms the conventional estimation of signal parameter via rotational technique CD（ESPRIT-CD） and propagator method CD（PM-CD）methods in terms of estimation accuracy. Furthermore, by means of the initialization via the propagator method, this paper accelerates the convergence procedure of the proposed algorithm with no estimation performance degradation. In addition, the proposed algorithm can be directly applied to the multiple-source scenario,where sources have different angular distribution shapes. Numerical simulation results corroborate the effectiveness and superiority of the proposed fast PARAFAC-based algorithm.

Discrimination of marine algal taxonomic groups based on fluorescence excitation emission matrix, parallel factor analysis and CHEMTAX

An in vivo three-dimensional fluorescence method for the determination of algae community structure was developed by parallel factor analysis （PARAFAC） and CHEMTAX. The PARAFAC model was applied to fluo-rescence excitation-emission matrix （EEM） of 60 algae species belonging to five divisions and 11 fluorescent components were identified according to the residual sum of squares and specificity of the composition profiles of fluorescent. By the 11 fluorescent components, the algae species at different growth stages were classified correctly at the division level using Bayesian discriminant analysis （BDA）. Then the reference fluo-rescent component ratio matrix was constructed for CHEMTAX, and the EEM-PARAFAC-CHEMTAX method was developed to differentiate algae taxonomic groups. The correct discrimination ratios （CDRs） when the fluorometric method was used for single-species samples were 100% at the division level, except for Bacil-lariophyta with a CDR of 95.6%. The CDRs for the mixtures were above 94.0% for the dominant algae species and above 87.0% for the subdominant algae species. However, the CDRs of the subdominant algae species were too low to be unreliable when the relative abundance estimated was less than 15.0%. The fluorometric method was tested using the samples from the Jiaozhou Bay and the mesocosm experiments in the Xiaomai Island Bay in August 2007. The discrimination results of the dominant algae groups agreed with microscopy cell counts, as well as the subdominant algae groups of which the estimated relative abundance was above 15.0%. This technique would be of great aid when low-cost and rapid analysis is needed for samples in a large batch. The fluorometric technique has the ability to correctly identify dominant species with proper abundance both in vivo and in situ.

Assessment of phytoplankton class abundance using fluorescence excitation-emission matrix by parallel factor analysis and nonnegative least squares

The feasibility of using fluorescence excitation-emission matrix(EEM) along with parallel factor analysis(PARAFAC) and nonnegative least squares(NNLS) method for the differentiation of phytoplankton taxonomic groups was investigated. Forty-one phytoplankton species belonging to 28 genera of five divisions were studied. First, the PARAFAC model was applied to EEMs, and 15 fluorescence components were generated. Second, 15 fluorescence components were found to have a strong discriminating capability based on Bayesian discriminant analysis(BDA). Third, all spectra of the fluorescence component compositions for the 41 phytoplankton species were spectrographically sorted into 61 reference spectra using hierarchical cluster analysis(HCA), and then, the reference spectra were used to establish a database. Finally, the phytoplankton taxonomic groups was differentiated by the reference spectra database using the NNLS method. The five phytoplankton groups were differentiated with the correct discrimination ratios(CDRs) of 100% for single-species samples at the division level. The CDRs for the mixtures were above 91% for the dominant phytoplankton species and above 73% for the subdominant phytoplankton species. Sixteen of the 85 field samples collected from the Changjiang River estuary were analyzed by both HPLC-CHEMTAX and the fluorometric technique developed. The results of both methods reveal that Bacillariophyta was the dominant algal group in these 16 samples and that the subdominant algal groups comprised Dinophyta, Chlorophyta and Cryptophyta. The differentiation results by the fluorometric technique were in good agreement with those from HPLC-CHEMTAX. The results indicate that the fluorometric technique could differentiate algal taxonomic groups accurately at the division level.

Characterization of dissolved organic matter in urban sewage using excitation emission matrix fluorescence spectroscopy and parallel factor analysis

Wastewater dissolved organic matter （DOM） from different processing stages of a sewage treatment plant in Xiamen was characterized using fluorescence and absorption spectroscopy. Parallel factor analysis modeling of excitation-emission matrix spectra revealed five fluorescent components occurring in sewage DOM： one protein-like （C1）, three humic-like （C2, C4 and C5） and one xenobiotic-like （C3） components. During the aerated grit chamber and primary sedimentation tank stage, there was only a slight decrease in fluorescence intensity and the absorption coefficient at 350 nm （a 350 ）. During the second aeration stage, high concentration of protein-like and short-wavelength-excited humic-like components were significantly degraded accompanied by significant loss of DOC （80%） and a 350 （30%）, indicating that C1 and C2 were the dominant constituents of sewage DOM. As a result, long-wavelength- excited C4 and C5 became the dominant humic-like components and the DOM molecular size inferred from the variation of spectral slope S （300–650 nm） and specific absorption （a 280 /DOC） increased. Combination use of F max of C1 and the ratio of C1/C5, or a 350 may provide a quantitative indication for the relative amount of raw or treated sewage in aquatic environment.

Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis

Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(Radj2)(0.963-0.998).The photo-degradation rate constants(kn) showed differences of three orders of magnitude,from 1.09 × 10-6 to 4.02 × 10-4 min-1,and half-life of multi-order model(T1/2n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(PⅠ,n) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(PⅡ,n,while the largest decrease ratio was found for C3 components,and the lowest T1/2n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM.

Joint frequency,2-D DOA,and polarization estimation using parallel factor analysis

This paper proposes a new algorithm for joint frequency, two-dimensional （2-D） directions-of-arrival （DOA）, and polarization estimation using parallel factor （PARAFAC） analysis model and cumulant. The proposed algorithm designs a new array configuration, and extends the PARAFAC analysis model from the common data-domain and subspace-domain to the cumulant one, and forms three-way arrays by using the three cumulant matrices obtained from the properly chosen dipole outputs, and analyzes the uniqueness of low-rank decomposition of the three-way arrays, and then jointly estimates the source parameters via the low-rank decomposition of the constructed PARAFAC model. In comparison with the conventional methods, the proposed method alleviates the aperture loss, and avoids pairing parameter. Finally, the simulation results are presented to validate the performance of the proposed method.

4-D parameter estimation of narrowband sources based on parallel factor analysis

A novel algorithm is presented in this paper to jointly estimate frequency, two-dimensional (2-D) direc- tion-of-arrival (DOA), and range of near-field narrowband sources. The proposed method extends the parallel factor (PARAFAC) analysis model from the common data- and subspace-domain to the cumu- lant one, and forms three-way arrays by using the five cumulant matrices obtained from the array out- puts, and analyzes the uniqueness of low-rank decomposition of the three-way arrays, then jointly es- timates source parameters via the low-rank decomposition. In comparison with the conventional methods, the proposed method alleviates the loss of the array aperture, and avoids pairing parameters. What is more important, this algorithm can deal with mixed far-field and near-field sources. Finally, the simulation results validate the performance of the proposed method.

A Parallel Probabilistic Approach to Factorize a Semiprime

In accordance with the distributive traits of semiprimes’ divisors, the article proposes an approach that can find out the small divisor of a semiprime by parallel computing. The approach incorporates a deterministic search with a probabilistic search, requires less memory and can be implemented on ordinary multicore computers. Experiments show that certain semiprimes of 27 to 46 decimal-bits can be validly factorized with the approach on personal computer in expected time.

APPLICATION OF NEWTON'S AND CHEBYSHEV'S METHODS TO PARALLEL FACTORJZATION OF POLYNOMIALS

In this paper it is shown m two different ways that one of the family of parallel iterations to determine all real quadratic factors of polynomials presented in [12] is Newton's method applied to the special equation (1.7) below. Furthermore, we apply Chebyshev's method to (1.7) and obtain a new parallel iteration for factorization of polynomials. Finally, some properties of the parallel iterations are discussed.

PARALLEL ITERATION FOR SPLITTING FACTORS OF POLYNOMIALS

In this paper we consider some parallel iterations for splitting quadratic factors of polynomials and their convergence.

ESTIMATION OF OVERALL EFFECTIVENESS FACTORS FOR PARALLEL CATALYTIC REACTIONS

Approximate analytical expressions of overall effectiveness factors for parallel catalytic reac-tions occurring in a spherical catalyst pellet with both internal and external mass transfer resistancesare obtained after taking the information given by asymptotic solutions valid for small and largevalues of Thiele moduli.This approximate procedure is feasible for power law as well asLangmuir-Hinshelwood kinetics and the agreement between the approximation and the numerical re-sults is good enough for practical purposes.Moreover,the method does not require any iterative ortrial-and-error computation,and can be conveniently applied in most practical calculations for reac-tors giving reliable results.

Magnetic-Flux-Controlled Giant Fano Factor for Coherent Tunneling Through a Parallel Double-Quantum-Dot

我们由采用解决数字的量率方程通过联合平行的量点干涉仪在通道报导我们零频率的射击噪音的研究。我们证明在二条小径和强壮的库仑排斥之间的量干扰效果的联合能导致一个巨大的 Fano 因素，它由调节围住的磁性的流动是可控制的。

Impact of transparent exopolymer particles on the dynamics of dissolved organic carbon in the Amundsen Sea,Antarctica

The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.

含钙添加剂处理下不同秸秆腐解产物可溶性有机质三维荧光特征变化

秸秆是优质的有机资源,研究含钙添加剂种类及添加量对不同秸秆腐解产物可溶性有机物(DOM)组成性质差异,可为秸秆高效腐熟利用提供理论依据和技术参考。以花生秸秆和水稻秸秆为供试物料,通过添加不同含钙添加剂草酸钙(CaC_(2)O_(4))和氢氧化钙[Ca(OH)_(2)]及不同添加量(4%、 8%),进行秸秆腐解试验。测定腐解产物养分含量,并利用三维荧光光谱(3DEEM)技术和平行因子方法(PARAFAC)探究秸秆腐解产物DOM的化学组成变化特征。结果表明:(1)总体上,草酸钙处理的秸秆腐解物总碳含量显著大于氢氧化钙处理;高量添加剂处理的秸秆腐解产物总碳含量小于低量处理;花生秸秆腐解产物的总氮、总磷和总钾高于水稻秸秆腐解产物。(2)通过3DEEM-PARAFAC方法分析腐解产物DOM组成,共识别出类胡敏酸(C1)、类胡敏酸(C2)和类色氨酸(C3)三种荧光组分;不同添加剂类型、添加量和不同秸秆类型对腐解产物DOM荧光组分的影响较为复杂,没有明显规律,但是总体上氢氧化钙处理的秸秆腐解产物DOM的C1和C2组分比例大于草酸钙处理,而草酸钙处理的秸秆腐解产物DOM的C3组分比例显著高于氢氧化钙处理;秸秆腐解产物DOM中组分C1、 C2与组分C3呈显著负相关;组分C2含量与总碳含量呈显著负相关。(3)氢氧化钙处理的秸秆腐解产物DOM的腐殖化指数(HIX)明显高于草酸钙处理,而草酸钙处理的秸秆腐解产物DOM生物源指数(BIX)明显高于氢氧化钙处理;高量草酸钙处理秸秆腐解产物DOM主要来自于微生物的转化,而其他处理DOM来自于微生物转化和陆生植物;不同添加量处理下秸秆腐解产物DOM的荧光指数没有明显变化规律;花生秸秆腐解产物DOM的HIX、 BIX和荧光指数(McKnight index)均高于水稻秸秆;秸秆腐解产物DOM中McKnight和HIX呈显著负相关,和BIX间呈极显著正相关,而秸秆腐解产物DOM中BIX和总碳含量呈显著正相关。上述结果表明,氢氧化钙可以促进秸秆腐解以及腐解产物的腐殖化,其中高量氢氧化钙处理的花生秸秆效果较好。

洞庭湖DOM组成与有机碳收支对江湖水力连通的响应

洞庭湖是我国最大的通江湖泊之一,为探究洞庭湖溶解性有机物(DOM)组成、(DOC)收支与江湖水力连通间的内在关联,于2018年5月、7月、9月和11月在洞庭湖湘、资、沅、澧4支流和长江荆南松滋、虎渡、藕池3个入湖口以及洞庭湖出湖口城陵矶采集水样,并探究洞庭湖流域DOM的组成分异特征及其对江湖水力连通的响应.结果表明,入湖河流和城陵矶DOM吸收系数a254和陆源类腐殖酸组分C1在7月最高.DOC由入湖口(2.4±1.3mg)/L下降至出湖口(2.1±0.3)mg/L,而a254由入湖口(9.7±2.2)m^(-1)上升至出湖口(10.1±1.7)m^(-1).微生物培养前的DOC浓度为(2.4±1.0)mg/L,微生物降解后的DOC浓度为(2.1±0.9mg)/L,DOC的微生物活性,即BDOC最高值出现在澧水为50.3%.5月、7月、9月和11月入湖的DOC通量分别为(63.7±43.6)×10^(3)t,(60.1±7.3)×10^(3)t,(27.6±3.6)×10^(3)t,(31.9±13.9)×10^(3)t.洞庭湖因自身水力滞留时间短,导致DOM在湖内运移过程中较少被降解,全湖DOM来源组成受流域不同季节来水条件影响较大.

资江流域江水DOM三维荧光特征及其对锑迁移的指示意义

溶解性有机质(dissolvedorganicmatter,DOM)是影响重金属元素在水体中迁移转化的关键因素之一。资江是洞庭湖第三大支流,流域内锑矿开发导致资江江水中锑(Sb)的质量浓度处于较高水平。为了解析资江流域江水中DOM的特征及来源,探索DOM对Sb迁移的指示意义,研究对资江流域江水进行了三维荧光光谱分析,利用平行因子法分析了水体中DOM的组分和荧光特征以及各组分与Sb质量浓度的关联。结果表明:(1)资江流域江水中Sb质量浓度为1.50~62.20μg/L,平均值为7.26μg/L,其中有55.56%的采样点Sb质量浓度超过最低限制5μg/L;(2)资江流域江水DOM有C1、C2和C3共3个组分,依次为陆源的类富里酸组分、类腐殖质组分以及可作为电子运输工具的醌类腐殖质组分,以C1和C2组分为主;(3)DOM主要通过2种方式影响Sb的迁移,一是水体中DOM的醌类基团作为电子传递体并参与有机质的氧化及铁氧化物的还原,二是富里酸基团与Sb进行络合形成DOM-Sb型复合物,2种方式协同促进了资江流域江水中Sb的富集,提高了Sb的迁移能力。研究结果将为资江流域江水Sb污染溯源和防治提供新的方向和理论依据。

北京市温榆河-北运河水系水质空间分布特征研究

采用水体三维荧光光谱(3D-EEMs)结合平行因子分析(PARAFAC)方法,研究了温榆河-北运河水系溶解性有机物(DOM)的荧光组分及其空间分布特征,并对沿岸污水处理厂、支流、干流的水质参数及其DOM组分之间的相互作用进行了分析。结果表明:温榆河-北运河水系干流溶解性有机碳(DOC)浓度与各支流接近,总磷浓度从上游到下游逐渐降低,氨氮和总磷污染严重。水体DOM共存在2类(4种)荧光组分,包括类腐殖质组分(类腐殖酸,C1;类富里酸,C2)和类蛋白组分(类色氨酸,C3;微生物代谢产物,C4)。污水处理厂出水汇入各支流后,水体DOM中的类腐殖质组分的比例上升。荧光比例显示,各河流DOM以C3组分为主,占比为24.76%~40.27%。水体荧光指数(1.58~1.72)、自生源指数(0.96~1.17)及腐殖化指数(0.74~0.81)计算结果指明,该水体的DOM组成具有内源和外源的双重特性,整体腐殖化程度低且自生源特性强。DOC与C1、C2和C4组分呈现极显著正相关,表明荧光组分可用于动态跟踪河流有机物;总氮与C1、C2组分呈极显著正相关,说明类腐殖质组分会对氮污染物浓度产生重要影响;总磷与自生源指数呈显著负相关(P<0.05),表现为DOM腐殖化程度越高,总磷浓度越低。

基于EEM-PARAFAC的荧光示踪剂检测方法的研究

在油田的注水开发中,利用化学示踪剂进行井间连通性测试是了解出水优势通道特征、制定提高采收率方案的必要前提。但常见的荧光示踪剂在现场应用中易受原油中荧光物质的干扰导致识别率和检测精度较低,严重影响测试结果的准确性。采用三维荧光光谱法与平行因子分析法相结合的分析方法,对在多种荧光物质干扰下的模拟采出液中的荧光示踪剂进行定性分析与定量分析,成功得出模拟采出液中荧光示踪剂浓度,经计算平均相对误差约为12.75%。该方法用三维荧光光谱的数据处理代替传统的荧光背景测试,去除模拟采出液中不同荧光物质对待检测示踪剂的干扰,具有操作简单、准确性高、成本低、检测速度快的特点,可广泛应用于复杂背景条件下荧光示踪剂的快速检测。

喀斯特湖泊-河流系统溶解性有机质光谱特征

为探索喀斯特湖泊-河流系统溶解性有机质(DOM)光谱特征空间格局,该研究以我国贵州红枫湖、百花湖和老马河为对象,分析了表层水体DOM紫外参数(SUVA_(254)、SUVA_(280)、S_(275—295)、S_(350—400)、S_(R)和E2/E3),利用三维荧光-平行因子(EEM-PARAFAC)解析DOM主要成分,同时基于荧光参数(HIX、FI、BIX和β∶α)揭示其来源信息。该研究运用Spearman相关性分析及主成分分析(PCA)方法,揭示DOM参数的内在联系及重要组分贡献。结果显示,红枫湖、百花湖和老马河SUVA_(254)和SUVA_(280)值较低,而E2/E3、S_(275—295)和S_(350—400)值较高,说明芳香类成分占比较少且DOM整体分子量较小。水体DOM主要成分为:红枫湖/百花湖(C1:微生物代谢类腐殖质;C2:可见光范围腐殖质;C3:色氨酸),老马河(C1:色氨酸;C2:富里酸;C3:陆源类腐殖质)。水体BIX范围在0.77—1.12之间,说明生物源和陆源输入共同贡献DOM。红枫湖与百花湖FI值小于1.4,而老马河在1.4—1.9间,说明河流内源DOM贡献率高于湖泊。水体β∶α值范围在0.73—1.10之间,说明新生DOM具有显著贡献。湖泊与河流HIX值低于4,表明水体腐殖化程度低。老马河HIX与S_(R)和S_(275—295)呈正相关(P<0.05)且与FI呈负相关(P<0.05),说明DOM腐殖化程度与分子大小和来源密切联系。芳香类DOM的同质性导致SUVA_(254)和SUVA_(280)相互耦合。研究发现新生DOM多具有生物降解性,表现为BIX和β∶α强相关。相对于激流系统,湖泊具有更多的水力停留时间,这可能进一步促进内源微生物的代谢,导致生物驱动的有机质快速循环,因此不同DOM生物讯号相互耦合。研究阐明了喀斯特湖泊-河流系统DOM成分与来源特征,有望为研究全球碳循环过程提供数据支撑。

9-羟基菲对α-葡萄糖苷酶的活性影响及相互作用研究

α-葡萄糖苷酶(GAA)作为一类重要的糖苷水解酶,是维持人体血糖平衡的重要功能性蛋白质。长期以来,为实现高血糖人群的降糖,研究人员多关注于探寻具有GAA活性抑制作用的食品、药品,但鲜有研究关注于人体非主动摄取的外源物质对GAA正常生理功能可能产生的影响。该研究选取典型多环芳烃类物质—菲的羟基代谢产物9-羟基菲(9-OHPhe),探究其对GAA活性功能的影响及潜在机制。为获得9-OHPhe与GAA的结合作用信息,PARAFAC法被应用于光谱重叠的9-OHPhe和GAA的三维荧光光谱(EEM)数据的解析,同时分子对接法被运用于分析分子层面两者结合的微观信息。9-OHPhe对GAA的活性有抑制作用,相应的IC50值为(7.59±1.91)μmol L^(-1);PARAFAC可有效应用于荧光光谱重叠的GAA和9-OHPhe反应体系的荧光数据解析;9-OHPhe可引起GAA内源荧光的静态猝灭,两者能形成1∶1复合物,在298 K下其结合常数为(8.91±0.68)×10^(3) L·mol^(-1);9-OHPhe与GAA的GLN281、LEU305、ASN319、LEU321、TYR322、LEU323和TYR352之间产生了疏水作用力,与GLN309和ASN319分别形成了键长为2.71和3.05Å的氢键;低浓度的9-OHPhe可使GAA的二级结构变得稳定,但过高浓度的9-OHPhe则会破坏GAA的结构稳定性。9-OHPhe对GAA活性有明显抑制效应,提示相关外源污染物进入健康人体后经这一途径所可能引起的血糖平衡紊乱值得关注和深入研究。