Collaborative optimization of exhaust gas recirculation and Miller cycle of two-stage turbocharged marine diesel engines based on particle swarm optimization

To meet increasingly stringent emission standards and lower the brake-specific fuel consumption(BSFC)of marine engines,a collaborative optimization study of exhaust gas recirculation(EGR)and a Miller cycle coupled turbocharging system was carried out.In this study,a one-dimensional numerical model of the EGR,Miller cycle,and adjustable two-stage turbocharged engine based on WeiChai 6170 marine diesel engine was established.The particle swarm optimization algorithm was used to achieve multi-input and multi-objective comprehensive optimization,and the effects of EGR-coupled Miller regulation and high-pressure turbine bypass regulation on NO_(x)and BSFC were investigated.The results showed that a medium EGR rate-coupled medium Miller degree was better for the comprehensive optimization of NO_(x)and BSFC.At medium EGR rate and low turbine bypass rates,NO_(x)and BSFC were relatively balanced and acceptable.Finally,an optimal steady-state control strategy under full loads was proposed.With an increase in loads,the optimized turbine bypass rate and Miller degree gradually increased.Compared with the EGRonly system,the optimal system of EGR and Miller cycle coupled turbine bypass reduced NO_(x)by 0.87 g/(kW·h)and BSFC by 17.19 g/(kW·h)at 100%load.Therefore,the EGR and Miller cycle coupled adjustable two-stage turbocharging achieves NO_(x)and BSFC optimization under full loads.

Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (I center dot 4.6 mm x 5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 mu m. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.

Stability of the Dividing Distribution Function Method for ParticleSize Distribution Analysis in Small Angle X－Ray Scattering

The Dividing Distribution Function (DDF) method is one of the methods by which the particle size distribution of ultrafine powder can be evaluated from its small angle X-ray scattering data. In this paper, the stability of the solution obtained from DDF method has been investigated through optimizing the coefficient matrix, introducing a damping factor and a least square treatment. All calculations were accomplished with a microcomputer. It was shown that the average deviations of the size distribution obtained are not larger than the assigned random errors to the scattering intensities as long as the corresponding requirements are satisfied.

STRUCTURAL DETERMINATION OF TITANIUM-OXIDE NANOPARTICLES BY X-RAY ABSORPTION SPECTROSCOPY

As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.

X-Ray Analysis by Williamson-Hall and Size-Strain Plot Methods of ZnO Nanoparticles with Fuel Variation

In this paper, a simple and facile surfactant assisted combustion synthesis is reported for the ZnO nanoparticles. The synthesis of ZnO-NPs has been done with the assistance of non-ionic surfactant TWEEN 80. The effect of fuel variations and comparative study of fuel urea and glycine have been studied by using characterization techniques like X-ray diffraction (XRD), transmission electron microscope (TEM) and particle size analyzer. From XRD, it indicates the presence of hexagonal wurtzite structure for ZnO-NPs. Using X-ray broadening, crystallite sizes and lattice strain on the peak broadening of ZnO-NPs were studied by using Williamson-Hall (W-H) analysis and size-strain plot. Strain, stress and energy density parameters were calculated for the XRD peaks of all the samples using (UDM), uniform stress deformation model (USDM), uniform deformation energy density model (UDEDM) and by the size-strain plot method (SSP). The results of mean particle size showed an inter correlation with W-H analysis, SSP, particle analyzer and TEM results.

A Particle Induced X-Ray Emission (PIXE) Analysis of Heavy Metals in Soil and Plantain (<i>Musa paradisiaca</i>) Leaves at an Artisanal Gold Mining Settlement in Southwestern Nigeria

The study examined the contamination levels of the soil and plantain leaves in three communities in Atakunmosa west local government area of Osun State in southwest Nigeria, where gold mining activities have recently become intensive. Plantain is a major food crop, whose leaves are used to wrap food items for household consumption. The objectives were to examine the heavy metal concentrations in the soil and plantain leaves around the gold mine site and compare them with standard recommended safe limits for the environment. Soil and plantain leaves were sampled at different locations around the sites and at a control site from a neighboring local government area with no history of gold mining activities between March 2015 and February 2016. Both soil and leave samples were processed and analyzed for selected heavy metals (Cd, As, Cu, Zn, Cr, Mn and Fe) using the Particle Induced X-ray Emission (PIXE) in the laboratory. The study showed higher concentrations than the World Health Organization’s recommended safe limits of the heavy metals in the soils and plantain leaves. Dry season concentrations of the variables were also higher than the wet season and the heavy metal concentrations at the control station were significantly (p < 0.05) lower than those of the mining environment. The study concluded that the ecosystems in the artisanal gold mining region are vulnerable to bioaccumulation of heavy metals and the leaves from the sites are sources of heavy metal contamination if consumed or used to wrap food items.

X射线激励XLPE电缆终端金属颗粒局部放电的研究

金属颗粒是电缆附件的典型缺陷之一,然而微小的金属颗粒缺陷局部放电难以检测。为此,该文提出了用X射线激励电缆终端金属颗粒缺陷局部放电的方法。首先,在电缆终端模拟实验模型上研究了X射线照射对不同电场分布、不同规格尺寸金属颗粒缺陷局部放电的影响;其次,探究了不同X射线强度下缺陷模型的放电特性;最后,在10 kV电缆终端上对该方法进行了测试。结果表明,X射线照射能降低金属颗粒缺陷的局部放电起始电压,降低幅度在11.4%~29.3%之间;与无X射线时相比,X射线照射能增大金属颗粒缺陷的放电重复率,增大幅度在36.1%~726.2%之间;X射线对金属颗粒缺陷的放电量无明显影响;X射线强度越高,对缺陷放电次数的激励效果越明显。在10 kV电缆上的测试结果验证了该方法的可行性,研究结果可为电缆附件缺陷局部放电检测提供一种新的手段。

新夸克模型对X(1835)特性的计算

根据新夸克模型,推断出X(1835)为六夸克结构,其主要衰变方式为Xγπ+π-η’,质量为m=1 835 Mev/c2,宽度为Γ=65±16 Mev/c2,寿命为τ(x)=1.01×10-23s,产生总截面σT=112.6 nb,分析的结果与最近BES协作组公布的实验结果完全一致.

医用X射线防护材料的研究进展

介绍了医用X射线与生物系统的相互作用机理及物理防护原理,分析了具有医用X射线屏蔽能力的柔性复合材料的研究进展。探讨了铅、铋、钨等防X射线功能颗粒及聚合物基材的性能特征,总结了涂层法、溶胶-凝胶法、纺丝法等成型方法的优缺点。研究表明,现有X射线防护材料在提升防护效果和使用便捷性方面具有重要意义,但面临性能优化和成本控制方面的挑战。未来研究应聚焦新型功能颗粒的开发、复合材料结构设计的优化及环保高效屏蔽材料的探索等方面,以进一步提升医用X射线防护材料的性能,拓宽其应用前景。

Tests for individual Sulfate－Containing Particles in Urban Atmosphere in Beijing

Thin film methods and X ray energy dispersive technique were applied to analyze sulfate-containing particles inBeijing in order to examine their features and sources. Atmospheric aerosol particles were collected on electron microscope meshes according to two size ranges: coarse particles (r>0.5μm) and fine particles (0.5μm>r>0. 1μm) by using a two-stage impactor. It was found that more than seventy percent of the fine particles and about twenty percentof the coarse particles were sulfate-containing particles. These particles were formed mainly through heterogeneousnucleation. The element composition analyses revealed that the atmospheric aerosol particles in Beijing were domi-nated by crustal particles and construction dust.

Elementary Particles Result from Space-Time Quantization

We justify and extend the standard model of elementary particle physics by generalizing the theory of relativity and quantum mechanics. The usual assumption that space and time are continuous implies, indeed, that it should be possible to measure arbitrarily small intervals of space and time, but we ignore if that is true or not. It is thus more realistic to consider an extremely small “quantum of length” of yet unknown value a. It is only required to be a universal constant for all inertial frames, like c and h. This yields a logically consistent theory and accounts for elementary particles by means of four new quantum numbers. They define “particle states” in terms of modulations of wave functions at the smallest possible scale in space-time. The resulting classification of elementary particles accounts also for dark matter. Antiparticles are redefined, without needing negative energy states and recently observed “anomalies” can be explained.

Effect of Zn Substitution on the Magnetic Properties of Cobalt Ferrite Nano Particles Prepared Via Sol-Gel Route

Zinc substituted cobalt ferrite nanoparticles (CoxZn1-xFe2O4, with x = 0.0, 0.2, 0.4, 0.8 and 1.0) were prepared via sol-gel route and the effect of zinc concentration on saturation magnetization and lattice parameter were investigated. The particle sizes of the as obtained samples were found to be ~10 nm which increases upto ~92 nm on annealing at 1000oC. The frequency bands near 564-588 cm-1 and 425-442 cm-1 are assigned to the tetrahedral and octahedral clusters which confirm the presence of M-O stretching band in ferrites. The unit cell parameter ‘a’ increases linearly with increasing concentration of zinc due to larger ionic radii of Zn2+ ion . It was found that this substitution allows tunable changes in the magnetic properties of cobalt ferrite. Interestingly, saturation magnetization first increases upto x = 0.4 and then decreases for higher Zn substitution, thus tunable changes in magnetic properties of cobalt ferrite are possible. Source of such behaviour could be the variation of exchange interaction between the tetrahedral and the octahedral sites.

超新星遗迹和脉冲星风云的X射线偏振成像

年轻超新星遗迹和脉冲星风云中的高能粒子可以通过同步辐射产生X射线。对该辐射的偏振测量有助于揭示粒子加速区磁场的性质,进而研究粒子加速的机制。首颗X射线偏振成像卫星于2021年底发射升空,已揭示了数个年轻超新星遗迹和脉冲星风云的X射线偏振图像。观测显示,仙后A和第谷超新星遗迹的偏振度较低,平均值分别约为2.5%和9%;而蟹状星云和船帆脉冲星风云的偏振度较高,平均值分别约为20%和45%。结果表明脉冲星风云的磁场较为有序,而两个年轻超新星遗迹的粒子加速区磁场是高度湍动的,且激波附近的磁场结构呈现径向分布。未来,随着对IXPE的使用越来越广泛,以及与我国建设中的增强型X射线时变与偏振探测器(eXTP)等更多望远镜投入使用,以上两类天体的磁场构型和粒子加速模型将得到进一步的限定。

COMPARISON OF VARIOUS PARTICLE SIZING TECHNIQUES

SEM,TEM, gas absorption, X-ray Sedi-graph and laser particle sizing have been employed to analyse particle size distribution and powder agglomeration for Alcoa A16 and for Sumitomo AKS-53B and SKP-53 alpha - Al2O3 powders on several occasions as well. Comparison and evaluation of various particle-sizing techniques have been made.

基于动态粒子群优化的X结构Steiner最小树算法

Steiner最小树(SMT)是总体布线的最佳连接模型,其构造是1个NP-难问题。粒子群优化(PSO)算法在解决NP-难问题中具有良好的表现,而PSO算法中种群的拓扑结构及搜索信息的传递机制对其性能有着很大的影响。1个适用于具体问题的种群拓扑结构对算法性能的提升极为显著。因此,利用PSO求解总体布线问题需要根据具体布线问题的特性来选择合适的粒子拓扑结构策略,以提升PSO的性能。提出基于动态PSO的X结构Steiner最小树(XSMT)算法以解决总体布线问题。首先,设计动态子群与信息交换策略,对种群进行子群划分,引入信息交换的概念,让子群在保持独立性的同时与其他子群进行信息交换,增加子群多样性;其次,设计粒子学习与变异策略,通过设置子群中粒子的学习对象使子群趋向于全局最优,并选择每个子群中适应度值最好的粒子进行变异,使粒子更易于跳出局部最优;最后,设计从多群局部学习过渡到单群全局学习策略,使算法在迭代次数到达阈值之后从局部学习过渡到全局学习,使得粒子在较优拓扑结构的基础上内部连接以获得更好的线长优化率。实验结果表明,与现有的2种R结构SMT(RSMT)算法相比,所提算法在优化线长方面分别优化了10.25%、8.24%;与现有的3种XSMT算法相比,该算法在优化线长方面分别优化了2.44%、1.46%、0.48%,验证了算法的有效性。

基于峰值多层级支持向量机的X射线通信解调技术研究

X射线通信技术是一种以X射线为载波的空间通信方式,它具有通信带宽大、重量轻、体积小、功耗低、保密性高等优势。通过设计多靶材X射线信号调制装置可以提高X射线的通信速率,在信号接收端要保证X射线能谱的识别准确率,才能真正发挥基于能量负载的X射线通信的优势。本文针对多靶材X射线特征能谱精确识别问题,提出基于峰值多层级支持向量机的X射线通信解调方法,设计了适合四码元通信的峰值多层级支持向量机分类器,通过参数调优和验证确保了高准确率和泛化能力。仿真结果证明:支持向量机为基于能量负载的X射线通信方法提供了高效、准确、鲁棒的信号识别解决方案。

Investigation of the performance of a pilot-scale barrel atmospheric plasma system for plasma activation of polymer particles

This study reports the development and performance of a pilot-scale barrel atmospheric plasma reactor for the atmospheric plasma activation treatment of polymer particles. The polymer particles treated included acrylonitrile butadiene styrene(ABS) and polypropylene(PP). These particles had diameters in the range of 3–5 mm. The initial studies were carried out using a laboratory-scale barrel reactor designed to treat polymer particle batch sizes of 20 g. A pilot-scale reactor that could treat 500 g particle batch sizes was then developed to facilitate pre-industrial-scale treatments. The effect of operating pulse density modulation(PDM) in the range 10%–100% and plasma treatment time on the level of activation of the treated polymers were then investigated. ABS revealed a larger decrease in water contact angle compared with PP after plasma treatment under the same conditions. The optimal treatment time of ABS(400 g of polymer particles) in the pilot-scale reactor was 15 min. The plasma-activated polymer particles were used to fabricate dog-bone polymer parts through injection molding.Mechanical testing of the resulting dog-bone polymer parts revealed a 10.5% increase in tensile strength compared with those fabricated using non-activated polymer particles.

不同Cu含量的Cu(X)/SSZ-13分子筛催化剂同时消除炭烟和NO_(x)的性能研究

柴油机由于其较强的动力性与耐久性等优势,已经广泛应用于运输、农业、建筑等重工业领域。然而,柴油机排放的尾气污染物,如炭烟颗粒和氮氧化物(NO_(x)),严重危害人们的健康和生活环境。因此,消除柴油机尾气中的炭烟颗粒和氮氧化物已成为一项重要的研究课题。通过控制原料中CuSO_(4)的添加量,采用一锅法合成了含有不同Cu含量的Cu(X)/SSZ-13分子筛催化剂。通过XRD、N_(2)吸附-脱附、SEM、H_(2)-TPR、NO-TPO、NH_(3)-TPD、Soot-TPR等表征手段,研究了制备的Cu(X)/SSZ-13分子筛催化剂的形貌和物理化学性质,并测试了所合成的催化剂在同时消除炭烟和NO_(x)方面的活性。结果表明,不同Cu含量的Cu(X)/SSZ-13分子筛在同时消除炭烟和NO_(x)方面的活性存在明显差异,Cu含量还会影响Cu(X)/SSZ-13分子筛的形貌、比表面积和氧化还原性能。当Cu含量为1.25时,制备的Cu(1.25)/SSZ-13催化剂表现出最佳的催化性能,其在153~427℃温度范围的NO转化率超过90%,炭烟燃烧的峰值温度(T_(m))为504℃。

Mineral Particles Found on the Hairs of Holy Maria-Magdalena Studied by Scanning Electron Microscopy and Elemental Analysis

The presumed hairs of Holy Maria-Magdalena are studied here for mineral particles found on their surfaces, by the techniques of scanning electron microscopy coupled with energy dispersive X-ray. Exploration by these techniques of the hair surfaces allows us to observe and study some marble fragments that can originate from the walls of the sarcophagus in which Maria-Magdalena’s remains were kept. These new findings support the authenticity of the hair as traditionally reported in the French “tradition des Saints de Provence”.

基于粒子群优化BP神经网络对保险杠的XRF光谱分类研究

建立了一种快速无损检验保险杠的分析方法。利用手持式X射线荧光光谱仪对50个保险杠样品进行了元素种类及含量的测量,根据K-means算法与轮廓系数、簇内误差平方和(SSE)的关系,确定最佳聚类数为5,即通过K-means聚类算法将50个样品分为5类。运用随机森林(RF)算法对样品的X射线荧光(XRF)光谱数据进行特征提取。根据RF算法提取的不同特征变量组合建立反向传播神经网络(BPNN)和粒子群(PSO)优化的BPNN(PSO-BPNN),结果表明:当输入变量为Ca-Pb-Sr 3种元素变量时,BPNN和PSO-BPNN均具有较好的分类效果,分类准确率分别为94%和98%;PSO-BPNN模型更适合此类样品的XRF光谱数据;XRF与PSO-BPNN相结合可以对保险杠实现有效分类。该方法简单、快速且无损样品,可为保险杠类物证鉴定提供科学依据。