DESL轮特征搜索算法的实现

DESL是一种轻量级分组密码,对于分组密码最常用的密码分析技术是差分密码分析。差分密码分析根据差分概率表搜索轮特征,采用C++语言实现了搜索轮特征的算法,并搜索得到了三轮、五轮等多种轮特征,为进一步的差分密码分析打下了基础。

中华倒刺鲃仔、稚鱼的耳石微结构与日轮形成特征

以中华倒刺鲃（Spinibarbus sinensis）亲鱼为材料,在实验室养殖条件下以人工孵化的丰年虫（Eubranchipus vernalis）为仔、稚鱼饵料,通过已知日龄法观察其耳石的微结构,分析其日轮形成特征。结果表明,仔、稚鱼的微耳石和矢耳石一般由1个中心核和1个耳石原基组成,少数存在多个中心核或原基现象,星耳石中心核和原基区分不明显。微耳石和矢耳石中心核直径分别为（37.73±5.34）μm和（39.78±7.11）μm,耳石原基直径分别为（16.29±3.46）μm和（17.09±3.88）μm。矢耳石和星耳石轮纹清晰度、规律性、周期性和完整性不及微耳石;微耳石第1条日轮在仔鱼出膜后第2天形成,以后每天沉积1轮。30日龄稚鱼微耳石轮纹数（N）与日龄（T）的关系符合直线模型,相关关系式为：N=1.0016T-0.8753（R2=0.9961,P〈0.01,n=197）,线性方程斜率与1无显著性差异（P〉0.05）。在微耳石和矢耳石样本中共观察到孵化标记轮和转移标记轮2种,其中孵化标记轮的出现率分别为78.68%和83.33%,转移标记轮的出现率分别为29.95%和48.98%。60尾33日龄稚鱼微耳石的生长轮宽度变化范围0.522-2.244μm,平均为（1.087±0.231）μm。

寿南小沙丁鱼鳞片表面结构及轮纹特征的扫描电镜观察

运用扫描电镜技术对寿南小沙丁鱼鳞片形态结构及轮纹特征进行了观察。研究结果表明:寿南小沙丁鱼鳞片属圆鳞,与鲱形鳞相似。鳞片上有多少不一呈断裂状的辐射沟,环片呈山嵴状,与辐射沟基本平行,环片脊顶上有许多大小不同的卤状粒突。鳞片侧区的年轮和副轮清晰,在与年轮相交处,环片明显呈下凹弯曲,少数发生断裂。

模型水轮机初生空化的特征谱提取识别方法

目前水轮机模型初生空化识别方法仍采用人工识别法,这种方法获得结果的周期较长、主观性强、准确度及效率都较低。针对于此,对水轮机模型初生空化识别方法进行了研究与优化创新,提出了一种基于炮声谱与特殊脉动谱特征提取的水轮机空化智能识别方法,即多态泡音智能识别方法 PSVFR。该方法依据自主开发的水轮机空化噪声多态算法MTCSPC,对数据进行处理,通过采集初生空化音态特征向量,建立矩阵模型,与样本数据库中的定性矩阵进行特征比对、计算、判断,以帮助机器完成对模型水轮机空化噪声的学习和识别。与现有技术相比,该方法能够提高机器对水轮机初生空化现象的识别准确度和识别效率,识别效率可达80%。

松潘裸鲤仔稚鱼耳石生长轮日周期确证及其孵化期推算

以2015年和2016年在孟屯河上游捕获的仔稚鱼为研究对象,对其种属进行了鉴定,观察了耳石形态特征、确证了耳石轮纹沉积规律,并基于耳石日轮技术对其孵化期进行了推算。结果表明:基于线粒体细胞色素氧化酶亚单位Ⅰ(Cytochrome oxidase subunitⅠ,COⅠ)序列构建的系统进化树显示,采集仔稚鱼为松潘裸鲤(Gymnocypris potanini)。在松潘裸鲤仔稚鱼生长过程中,微耳石由近圆形发育成贻贝形,矢耳石由锲形发育为箭矢状。采用温度标记处理松潘裸鲤仔稚鱼,确定耳石轮纹沉积具有日周期性,生长轮为日轮。依据耳石日轮数,结合采样时间及耳石轮纹沉积规律,并采用大多数裂腹鱼类日龄为日轮数N+1的关系,推算出2015年松潘裸鲤样本的孵化时间为6月29日至7月15日,2016年样本孵化时间为7月13日至8月18日,这些结果为研究松潘裸鲤野生种群繁殖期及其资源保护等提供了基础数据。

星形轮压痕作为喷墨打印机个体识别依据的实验研究

目的为喷墨打印机的个体识别提供一种有效特征。方法通过实验考察了46种喷墨打印机,运用薄型碳式复写纸采集喷墨打印机输纸机构中星形轮形成的机械压痕。分析复写纸上星形轮印迹所反映的机器个体特定性,并将这种复写印迹与正常打印件上显现出的成行点状压痕进行比较分析,考察星形轮压痕在普通纸、喷墨纸和照片纸不同打印介质上的反映。结果发现喷墨打印机星形轮压痕具有个体特殊性,对这种特征的利用需考虑墨迹密度、打印介质和显现方法的影响。结论有效显现和综合利用独特星形轮压痕特征可以使喷墨打印机的个体识别成为可能。

柳江下游大眼鳜仔稚鱼耳石特征及孵化期推算

【目的】分析柳江下游大眼鳜(Siniperca knerii)仔稚鱼的耳石形态变化和微结构特征,明确该江段大眼鳜的生长和繁殖现状,为其资源保护及合理开发利用提供理论依据。【方法】以2022年采集的柳江下游大眼鳜仔稚鱼为试验材料,经50%乙醇麻醉后测量体长(mm),用解剖针挑取耳石;采用温度标记法确证矢耳石轮纹增量周期;通过显微镜观察矢耳石和微耳石形态特征并统计耳石轮纹数,利用耳石日轮技术推算其孵化日期;通过Image J测量矢耳石与微耳石的长(μm)、宽(μm)、周长(μm)和面积(μm^(2))等形态指标,并计算环率、矩形趋近率、椭圆度、辐形比、外形尺寸和圆度等形状指数,比较两类尺寸等级(体长≤13 mm和体长>13 mm)的大眼鳜矢耳石形态变化,对大眼鳜矢耳石形态指标与体长关系进行拟合,采用AIC(Akaike information criterion)准则选取最适模型,分析二者间的关系。【结果】2022年采集的大眼鳜样本微耳石轮纹数范围为3~9轮,矢耳石轮纹数范围为6~16轮,矢耳石标记轮纹数与标记时间呈线性相关,大眼鳜矢耳石轮纹增量具有日周期性,用日轮数N+3表示日龄,推算2022年柳江下游江段大眼鳜样本的孵化期为5月1日—8月8日。随着大眼鳜仔稚鱼的生长,矢耳石由近圆形发育成一端略尖的桃形,微耳石由近圆形发育成贻贝形,矢耳石相较于微耳石变化更明显。拟合大眼鳜矢耳石的长、宽、周长和面积4个形态指标与体长的关系,以线性模型为最佳拟合模型,两类尺寸等级的大眼鳜矢耳石形态指标与体长相关性均较强,第二类R2大于第一类,两类尺寸等级的线性模型拟合效果无显著差异,表明大眼鳜仔稚鱼在早期生活阶段耳石形态与体长呈线性相关,且在一段时间内相关性逐步增强。【结论】柳江下游大眼鳜仔稚鱼孵化期整体短于珠江流域鳜属鱼类的自然繁殖期,矢耳石更适合作为大眼鳜早期年龄鉴定的器官,耳石的大小可作为判断该物种早期生长现状的重要依据。

CONTOUR EXTRACTION AND FEATURE POINT DETECTION FOR 3-D FRAGMENT REASSEMBLY

An approach to contour extraction and feature point detection in the 3-D fragment reassembly is proposed. A simple and effective technique is used for building the intrinsic topology of the fragment data suitable for contour extraction. For the scanned data in which the topology is difficult to be achieved, the corresponding solutions are given to manage this problem. A robust approach is used for the curvature and torsion calculation of the discrete contour in a 3-D space. Finally, a method is developed for detecting feature points of the fragment contour based on total curvature. Therefore, the contour description combines the simple global information with local feature points. Experiments with real contour curves extracted from 3-D fragments demonstrate that the proposed method is robust and efficient.

Sparseness-controlled non-negative tensor factorization and its application in machinery fault diagnosis

Aiming at the problems of bispectral analysis when applied to machinery fault diagnosis, a machinery fault feature extraction method based on sparseness-controlled non-negative tensor factorization （SNTF） is proposed. First, a non-negative tensor factorization（NTF） algorithm is improved by imposing sparseness constraints on it. Secondly, the bispectral images of mechanical signals are obtained and stacked to form a third-order tensor. Thirdly, the improved algorithm is used to extract features, which are represented by a series of basis images from this tensor. Finally, coefficients indicating these basis images＇ weights in constituting original bispectral images are calculated for fault classification. Experiments on fault diagnosis of gearboxes show that the extracted features can not only reveal some nonlinear characteristics of the system, but also have intuitive meanings with regard to fault characteristic frequencies. These features provide great convenience for the interpretation of the relationships between machinery faults and corresponding bispectra.

从深度学习视角探讨课堂对话:基于日常教学经验的观察

苏格拉底式的课堂对话,是一种通过话轮切换而不断加深、拓展知识结构以及构建意义的学习过程,在促进深度学习中有着一定的积极作用。B-I-R-C(P-R……)-E复式对话结构比I-R-F(E)或I-R-Rv-E更适于深度教学,其基本功能源自F-D-E结构。在课堂对话的教学实践中,应当关注教师话轮的引导性、学生话轮的发展性以及回应的不确定性,灵活运用或调适B-I-R-C(P-R……)-E结构,以期得到更佳的教学效果。

褐菖鲉幼鱼对贻贝养殖生境的利用规律初探

嵊泗海域规模庞大的贻贝养殖生境发挥着养护幼鱼的海洋牧场功能,而探查当地趋礁鱼类在幼体阶段对该生境的利用规律可为当地海洋牧场的设计提供重要参考,为此2018年5—7月对舟山北部枸杞岛贻贝场的褐菖鲉幼鱼、附着生物进行了逐月调查,使用自制网具采集目标生物样品,应用相对密度指数和相关分析法分析了褐菖鲉幼鱼在该生境中的栖息密度、栖息方式和空间分布特征,采用胃含物分析法确定其食性特征,并结合耳石轮纹探究其利用该生境的生长周期。结果显示,褐菖鲉幼鱼的栖息密度时空特征上,5—7月在养殖区贻贝串上的栖息密度分别为(10±6)、(7±5)和(5±5)个/串,时间上呈现逐月递减趋势,随时间的推移养殖区外侧幼体逐渐迁移至内侧近岸区直至消失。栖息方式选择上,褐菖鲉幼鱼栖息数量与贻贝串孔隙大小和附着海藻生物量之间皆呈正相关,但并不显著。饵料利用上,养殖区褐菖鲉幼鱼总体维持较高的摄食强度,各月份平均摄食强度皆高于对照区,主要摄食对象为麦秆虫和钩虾,重量百分比为70.9%和28.3%。栖息周期上,养殖区内褐菖鲉幼鱼耳石平均轮纹数为(57±12)个,其利用养殖贻贝串的周期一般约为2~3月,且该生境中幼鱼耳石纹路间距均匀性和条纹清晰度均明显优于岩礁生境。研究表明,枸杞岛的贻贝养殖生境成为褐菖鲉幼鱼额外的栖息环境,在增殖养护褐菖鲉资源方面发挥了积极作用,因此嵊泗海域在建设海洋牧场时可依据贻贝养殖生境的资源养护原理,通过设置浮体结构强化海洋牧场的饵料场和庇护功能,以提高褐菖鲉种群的补充量,为当地休闲海钓的持续发展提供部分保障。

A fault feature extraction method of gearbox based on compound dictionary noise reduction and optimized Fourier decomposition

Aimed at the problem that Fourier decomposition method(FDM)is sensitive to noise and existing mode mixing cannot accurately extract gearbox fault features,a gear fault feature extraction method combining compound dictionary noise reduction and optimized FDM(OFDM)is proposed.Firstly,the characteristics of the gear signals are used to construct a compound dictionary,and the orthogonal matching pursuit algorithm(OMP)is combined to reduce the noise of the vibration signal.Secondly,in order to overcome the mode mixing phenomenon occuring during the decomposition of FDM,a method of frequency band division based on the extremum of the spectrum is proposed to optimize the decomposition quality.Then,the OFDM is used to decompose the signal into several analytic Fourier intrinsic band functions(AFIBFs).Finally,the AFIBF with the largest correlation coefficient is selected for Hilbert envelope spectrum analysis.The fault feature frequencies of the vibration signal can be accurately extracted.The proposed method is validated through analyzing the gearbox fault simulation signal and the real vibration signals collected from an experimental gearbox.

I mpact of several harmful algal bloom(HAB) causing species, on life history characteristics of rotifer Brachionus plicatilis Müller

In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life history parameters of rotifers(B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom(S keletonema costatum) and four dinofl agellates( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi cum). Compared with the control treatment(CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production(CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span(CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate(CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., fi nite rate of increase(CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase(CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton, resulting in an increase in algal numbers.

Flooding Characteristics of Hydrofoil Impeller in a Two- and Three-phase Stirred Tank

The flooding characteristics of hydrofoil impeller were systematically investigated in a two-and three-phase 383 mm i.d. stirred tank operated on air, water and spherical glass beads. The volumetric solid concen-tration Cs was varied from 0 to 25%. And the superficial gas velocity Ug was at the range of 0-0.096 m·s-1. A fast and objective method for identifying flooding point NF is developed based on the statistical analysis of the pressure fluctuation signals. It is found, the effect of solid concentration on the flooding point NF depends on the gas velocity. At the lower gas velocity (Ug = 0.010 m·s-1), the solid concentration has only a minor effect. However, it displays a very significant effect on the flooding point NF at the medium and high gas velocity. The flooding point NF linearly increases with the gas velocity Ug, at lower solid concentration (Cs = 0, 10%). When Cs = 20%, the behavior of NF versus Ug becomes more complex. The correlations of the flooding characteristics in the slurry stirred tank are proposed by considering the solid concentration effect.

The Derivation of Skeleton Lines for Terrain Features

The geometric and physical analysis methods are conventional methods for the derivation of skeleton lines in the fields of cartography,digital photogrammetry,and related areas.This paper proposes a stepwise approach that uses the physical analysis method in the first stage and the geometric analysis method in the subsequent stage.The physical analysis method analyses the terrain globally to obtain a rough set of skeleton lines for a terrain surface.The rough skeleton lines help to structure the ordering of feature points by the geometric analysis method.

Why Fixed Slip Devices Can not Measure the Speed Gradient Due to the Pavement？

This paper covers why measurements at various speeds with CFME （continuous friction measurement equipment） are not able to measure the speed-friction gradient of the pavement as determined by the macro-textural features of the surface. Most CFMEs measure friction in the slip ratio range of 10% to 18%. In this range, it is shown that the friction versus slip speed of these devices are mainly determined by the coupled properties of the surface micro-texture and relevant tire properties and to a minimal extent only by pavement macro-texture properties. The determinacy of low slip ratio friction measurements on the macro-textural features of the pavement surface are shown to be so low that they are inadequate to capture macro-texture caused speed degradation of friction. It is also shown in the paper that close to 100% slip ratio measurements at a relatively wide speed scale or direct macro texture measurements are needed to adequately determine the speed gradient if friction caused by the pavement macro-texture. The data and analysis in this paper provide strong and compelling evidence that the EFI （European Friction Index） or EFI developed by the HERMES （Harmonization of European Routine and Research Measuring Equipment for Skid Resistance） project sponsored by FEHRL （Forum of European National Highway Research Laboratories） is strongly affected by the lack of consideration of this phenomenon. It is recommended that the results of the HERMES project are reviewed taking into account the findings of the present paper. Based on the results of the presented paper it is suggested that CFME＇s only measure friction at a fixed speed with a standard tire and use a macro-texture measuring device to obtain the pavement speed gradient.

A New Manufacturing Method for Hourglass Worm Gear Hob Based on a Semi⁃automatic CAD

The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the hob has been produced through different manufacturing techniques and machine tools,which results in low efficiency.To solve this problem,we propose a semi-automatic computer aided design(CAD)method for hobs.The point clouds of each feature surface of a hob are calculated by combing mathematical equations of the top relief surfaces built by the proposed method with other existing equations of hob surfaces.According to the point clouds,the method can achieve the automatic modeling for the hob in three-dimensional(3D)software by classifying and extracting the parameter information of the feature-hierarchical knowledge of the hob.Based on the generated 3D model,the entire surfaces of the hob can be manufactured on a four-axis computer numerical control(CNC)milling machine through only twice clamping.Verification of the width of the land surface of the hob manufactured by semi-automatic CAD method on a measuring projector proved the precision of the designed width can be ensured.The edge of the contact area on the worm wheel in a meshing experiment is clear and distinct,which means the worm gear drive is meshed well and the hob manufactured by the proposed method has improved machinability.The method simplifies the processing technique,and improves the design efficiency and production accuracy.

Open Contours Extraction of Rotational Surface Oriented to Layer Measurement

With layer-measured contours, an algorithm that can extract the contour segments from a rotational surface is presented. The extraction can be divided into two stages, i. e. the rough segmentation and the refinement. In the rough segmenting stage, an optimal contour matching method is put forward to find similar contour segment from another closed contour with respect to the seed contour. In the refining stage, an iterative way that can extract a circular arc precisely is presented based on parameters identification and contour-ends expanding/shrinking operation. The algorithm can extract the open contour segments from a rotational surface precisely, as demonstrated in the examples. Based on the work of this paper, further research, such as parameter identification of 3 - D surface and CAD model creation, can be conducted.

Eigenvalue Analysis of Distributed Generation Including Multimass Turbine Model

This paper presents small-signal study based on eigenvalue analysis as a preliminary study to observe the interaction between multimass turbine-generator system and inverter-based distributed generation in a microgrid. The multimass turbine model is included in the overall distributed generation system model. Two case studies are demonstrated to observe the interaction between turbine-generator set and power electronics-based distributed generation system. Both case studies are in stand-alone and grid-connected operation. It can be shown that under stand-alone operation, unstable oscillatory modes may occur and be highly influenced by the operating points of the system.

Feature extraction of gear-localized defect using adaptive lifting scheme and local gradient maps

In this paper,the adaptive lifting scheme (ALS) and local gradient maps (LGM) are proposed to isolate the transient feature components from the gearbox vibration signals. Based on entropy minimization rule,the ALS is employed to change properties of an initial wavelet and design adaptive wavelet. Then LGM is applied to characterize the transient feature components in detail signal of decomposition results using ALS. In the present studies, the orthogonal Daubechies 4 (Db 4) wavelet is used as the initial wavelet. The proposed method is applied to both simulated signals and vibration signals acquired from a gearbox for periodic impulses detection. The two conventional methods (cepstrum analysis and Hilbert envelope analysis) and the orthogonal Db4 wavelet are also used to analyze the same signals for comparison. The results demonstrate that the proposed method is more effective in extracting transient components from noisy signals.