基于改进K-prototypes与GBDT的城市干道车辆出行群体辨识模型

为了掌握城市干道交通运行规律,向交通管理部门制定相关交通需求管理政策提供理论依据,提出了一种基于组合模型的城市干道车辆出行群体辨识模型。基于青岛市胶州湾隧道过车数据,从出行强度、出行时间与出行习惯3个维度构建了出行特征指标体系以全面刻画车辆个体的出行行为。基于相关性分析剔除了冗余指标以避免对辨识研究的影响。针对混合属性出行特征指标数据,使用改进K-prototypes算法以有效地实现车辆出行群体划分,将其与GBDT算法相结合,建立了一种基于改进K-prototypes与GBDT的辨识模型,随机选取10000个样本开展辨识研究。结果表明:研究道路存在5类车辆出行群体:高频通勤群体、低频通勤群体、营运群体、频次稳定群体与普通群体,对于这5类车辆出行群体,平均识别准确率为97.75%,最高识别准确率可达99.47%。

Accelerated fracture healing by osteogenic Ti45Nb implants through the PI3K–Akt signaling pathway

The key to managing fracture is to achieve stable internal fixation,and currently,biologically and mechanically appropriate internal fixation devices are urgently needed.With excellent biocompatibility and corrosion resistance,titanium–niobium alloys have the potential to become a new generation of internal fixation materials for fractures.However,the role and mechanism of titanium–niobium alloys on promoting fracture healing are still undefined.Therefore,in this study,we systematically evaluated the bone-enabling properties of Ti45Nb via in vivo and in vitro experiments.In vitro,we found that Ti45Nb has an excellent ability to promote MC3T3-E1 cell adhesion and proliferation without obvious cytotoxicity.Alkaline phosphatase(ALP)activity and alizarin red staining and semiquantitative analysis showed that Ti45Nb enhanced the osteogenic differentiation of MC3T3-E1 cells compared to the Ti6Al4V control.In the polymerase chain reaction experiment,the expression of osteogenic genes in the Ti45Nb group,such as ALP,osteopontin(OPN),osteocalcin(OCN),type 1 collagen(Col-1)and runt-related transcription factor-2(Runx2),was significantly higher than that in the control group.Meanwhile,in the western blot experiment,the expression of osteogenic-related proteins in the Ti45Nb group was significantly increased,and the expression of PI3K–Akt-related proteins was also higher,which indicated that Ti45Nb might promote fracture healing by activating the PI3K–Akt signaling pathway.In vivo,we found that Ti45Nb implants accelerated fracture healing compared to Ti6Al4V,and the biosafety of Ti45Nb was confirmed by histological evaluation.Furthermore,immunohistochemical staining confirmed that Ti45Nb may promote osteogenesis by upregulating the PI3K/Akt signaling pathway.Our study demonstrated that Ti45Nb exerts an excellent ability to promote fracture healing as well as enhance osteoblast differentiation by activating the PI3K/Akt signaling pathway,and its good biosafety has been confirmed,which indicates its clinical translation potential.

北方地区污水厂应用高效活性污泥工艺进行提标改造

雄安新区某生活污水处理厂于2018年启动提标改造工程,出水水质由一级A标提升至Ⅳ类水体标准,其中出水TN 10 mg/L以下。因此该厂在保证原有工艺不停产、有足够用地的前提下,特增设高效活性污泥尾水处理构筑物。经过调试,该工程出水水质稳定,能实现类Ⅳ类水体出水要求,且运行成本合理,可为实现出水TN≦10 mg/L的污水厂作为借鉴。

Effects of bolt profile and grout mixture on shearing behaviors of bolt-grout interface

Shearing behavior and failure mechanism of bolt-grout interface are of great significance for load transfer capacity and design of rock bolting system.In this paper,direct shear tests on bolt-grout interfaces under constant normal load(CNL) conditions were conducted to investigate the effects of bolt profile(i.e.rib spacing and rib height) and grout mixture on the bolt-grout interface in terms of mechanical behaviors and failure modes.Test results showed that the peak shear strength and the deformation capacity of the bolt-grout interface are highly dependent on the bolt profile and grout mixture,suggesting that bolt performances can be optimized,which were unfortunately ignored in the previous studies.A new interface failure mode,i.e.'sheared-crush' mode,was proposed,which was characterized by progressive crush failure of the grout asperities between steel ribs during shearing.It was shown that the interface failure mode mainly depends on the normal stress level and rib spacing,compared with the rib height and grout mixture for the range of tested parameters in this study.

Tailoring Nitrogen Terminals on MXene Enables Fast Charging and Stable Cycling Na-Ion Batteries at Low Temperature

Sodium-ion batteries stand a chance of enabling fast charging ability and long lifespan while operating at low temperature(low-T).However,sluggish kinetics and aggravated dendrites present two major challenges for anodes to achieve the goal at low-T.Herein,we propose an interlayer confined strategy for tailoring nitrogen terminals on Ti_(3)C_(2) MXene(Ti_(3)C_(2)-N_(funct)) to address these issues.The introduction of nitrogen terminals endows Ti_(3)C_(2)-N_(funct) with large interlayer space and charge redistribution,improved conductivity and sufficient adsorption sites for Na^(+),which improves the possibility of Ti_(3)C_(2) for accommodating more Na atoms,further enhancing the Na^(+) storage capability of Ti_(3)C_(2).As revealed,Ti_(3)C_(2)-N_(funct) not only possesses a lower Na-ion diffusion energy barrier and charge trans-fer activation energy,but also exhibits Na^(+)-solvent co-intercalation behavior to circumvent a high de-solvation energy barrier at low-T.Besides,the solid electrolyte interface dominated by inorganic com-pounds is more beneficial for the Na^(+)transfer at the electrode/electrolyte interface.Compared with of the unmodified sample,Ti_(3)C_(2)-Nfunct exhibits a twofold capacity(201 mAh g^(-1)),fast-charging ability(18 min at 80% capacity retention),and great superiority in cycle life(80.9%@5000 cycles)at -25℃.When coupling with Na_(3)V_(2)(PO_(4))_(2)F_(3) cathode,the Ti_(3)C_(2)-N_(funct)//NVPF exhibits high energy density and cycle stability at -25℃.

不同密度和剂量猪精的深部输精对母猪繁殖性能的影响

适当降低每次输精时猪精的有效精子数可提高公猪利用效率、减少公猪饲养规模,同时能更充分地利用优秀的公猪。试验以15亿/80 mL规格猪精为对照组,比较12亿/80 mL、12亿/60 mL和10亿/60 mL规格猪精的深部输精对经产母猪繁殖性能的影响。结果显示:受胎率15亿/80 mL>12亿/60 mL>10亿/60 mL>12亿/80 mL,无显著性差异(P>0.05);分娩率15亿/80 mL>12亿/60 mL>12亿/80 mL>10亿/60 mL,无显著性差异(P>0.05);窝均总产仔数、窝均产活仔数、窝均出生重和头均出生重无显著差异(P>0.05)。综合来看,与对照组相比,12亿/60 mL组可以做到不影响繁殖性能,同时使猪精产能提升20%,有推广价值。

Comparative study of the chitooligosaccharides effect on the proliferation inhibition and radiosensitization of three types of human gastric cancer cell line

Objective:To observe the chitooligosaccharides(COS) effect on the proliferation inhibition and radiosensitivity of three types of human gastric cancer cell line.Mothods:CCK-8 assay was employed to obtain the inhibition ratio of COS on BGC823 cells,MKN45 cells and SGC7901 cells at 48 h after treatment and the proliferation-inhibition curve was drawn with the inhibition ratio of COS on three types of cells.The clonogenic assay was used to detect the cell viability of 0,1,2,4,6 and 8 Gy(6 dose grades) in RAY group and RAY+COS group after X-ray,and the cell survival curve was used to analyze the sensitization enhancement ratio of COS.Flow cytometry was employed to detect cell cycle and apoptosis rate in control group,RAY group and RAY+COS group after 48 h treatment.Results:COS inhibited the proliferation of three types of cells.The inhibition rate was positively correlated with the concentration of COS,and the susceptibility of MKN45 cells,SGC7901 cells and BGC823 cells to COS decreased in turn.The cell viability decreased gradually with the increasing radiation dose in RAY group and RAY+COS group(P<0.01).The cell viabilities of RAY+COS group were lower than those of RAY group at all the dose grades under X-ray exposure(P<0.01),and the sensitization enhancement ratios of COS on BGC823 cells,MKN45 cells and SGC7901 cells were 1.06,1.28 and 1.15 respectively.In controlled trials,apoptosis rate and percentage in the G_2/M phase of three types of cells in RAY+COS group were higher than those in control group and RAY group,and percentage in the S phase and the G_0/G_1 phase in RAY+COS group were lower than those in the other two groups(P<0.01).Conclusions:COS can inhibit the proliferation of three types of human gastric cancer cells and enhance the radiosensitivity by inducing apoptosis and G_2/M phase arrest.

Laboratory investigation into effect of bolt profiles on shear behaviors of bolt-grout interface under constant normal stiffness (CNS) conditions

Rock bolts have been widely used for stabilizing rock mass in geotechnical engineering.It is acknowledged that the bolt profiles have a sound influence on the support effect of the rock bolting system.Previous studies have proposed some optimal rib parameters(e.g.rib spacing);unfortunately,the interface shear behaviors are generally ignored.Therefore,determination of radial stress and radial displacement on the bolt-grout interface using traditional pull-out tests is not possible.The load-bearing capacity and deformation capacity vary as bolt profiles differ,suggesting that the support effect of the bolting system can be enhanced by optimizing bolt profiles.The aim of this study is to investigate the effects of bolt profiles(with/without ribs,rib spacing,and rib height)on the shear behaviors between the rock bolt and grout material using direct shear tests.Thereby,systematic interfacial shear tests with different bolt profiles were performed under both constant normal load(CNL)and constant normal stiffness(CNS)boundary conditions.The results suggested that rib spacing has a more marked influence on the interface shear behavior than rib height does,in particular at the post-yield stage.The results could facilitate our understanding of bolt-grout interface shear behavior under CNS conditions,and optimize selection of rock bolts under in situ rock conditions.

基于广义CP张量分解和多尺度排列熵的液压泵故障诊断

针对现有液压泵故障诊断算法故障识别精度低、实测信号中存在冗杂信息和无关成分干扰等问题,提出了一种在高维空间对液压泵振动信号进行处理和模式识别的方法。首先利用Lowner矩阵将一维时间序列信号进行高维张量化,然后基于广义CP张量分解(GCP)算法,根据数据分布类型选择适当的损失函数以确定最佳低秩模型,实现对液压泵采集得到的振动信号进行分解,降低分解损失,提高分解精度。最后选择分解结果中与原始信号相似度最高的模式分量,计算其多尺度排列熵(MPE)值进行液压泵不同故障类型的特征识别。将该文所提方法应用于液压泵故障实验台的实测数据分析,验证了其在液压泵故障诊断中的有效性。

观光车风险及防控措施

为使观光车使用单位规范使用和管理观光车,确保安全行驶,提出观光车存在的风险。观光车的风险主要存在人(驾驶员、乘车人员、管理人员),车及环境三个主要因素,文中针对风险制定了具体的防控措施,防患于未然。

基于QSTFT的同步压缩变换及在轴承故障诊断中的应用

高阶同步压缩变换以同步压缩变换为基础,能够有效地估计纯调制信号的瞬时频率,提升时频面的能量集中水平。但由于受到窗口固定的限制,其难以对频率快速变化的多分量信号获得清晰的时频表示。为此,引入缝式短时傅里叶变换,其能够根据信号的特点,在特定区域自适应地选择最佳的窗口,克服了窗口时宽不变的缺陷。在此基础上,结合高阶同步压缩变换,提出一种基于缝式短时傅里叶变换的自适应高阶同步压缩变换算法,进一步提升对复杂信号时频特征的提取能力。通过对仿真信号和轴承外圈故障信号进行分析,验证了该算法的有效性。

公猪繁殖性能评定

随着规模化养猪业的发展及人工授精技术的普及,公猪繁殖性能已是影响猪场经济效益的重要因素。如何准确评定公猪的繁殖能力,保证人工授精效果,进而保证母猪的繁殖性能的发挥,是养猪人工作中的重要环节。生产实践中最常用的是通过显微镜对猪精细胞水平进行检测。科研人员也在一直研究影响人工授精效果的因素,将精液的检测从细胞水平上升至分子水平,再用分子标记手段将公猪繁殖性能由检测提前至预测,最大限度地保证公猪的繁殖性能,保证优良公猪的性能得到最大程度的发挥。文章从精液品质、人工授精效果、分子水平检测、标记物等几个方面介绍公猪繁殖性能评价时需要衡量的指标,为公猪繁殖性能评定提供参考。

Comparative Study of 3D-Printed Porous Titanium Alloy with Rod Designs of Three Different Geometric Structures for Orthopaedic Implantation

Porous titanium alloy is currently widely used in clinical treatment of orthopaedic diseases for its lower elastic modulus and ability to integrate with bone tissue.At the micro-level,cells can respond to different geometries,and at the macro-level,the geometric design of implants will also affect the biological function of cells.In this study,three kinds of porous scaffolds with square,triangular and circle rod shapes were designed and 3D printed.This study observed the proliferation and differentiation of MC3T3-E1 cells during surface culture of the three types of scaffolds.It also evaluated the characteristics of the three scaffolds by means of compression tests and scanning electron microscopy to provide a reference for the design of porous titanium alloy implants for clinical applications.The trends of cell proliferation and gene expression between the three types of scaffolds were observed after treatment with two inhibitors.The results show that the square rod porous scaffolds have the best proliferative and osteogenic activities,and these findings may be due to differences in piezo-type mechanosensitive ion channel component 1(Piezo1)and Yes-associated protein(YAP)expression caused by the macro-geometric topography.

Four-coordinate disilyl cobalt(Ⅱ)complexes with NHC ligation:Synthesis,characterization,and reactivity

Silyl cobalt species are putative intermediates in cobalt-catalyzed transformations of hydrosilanes.However,their reactivity has remained poorly understood.Reported here is the investigation on four-coordinate disilyl Co(Ⅱ)complexes with N-hetereocyclic carbene ligation.The reactions of[(ICy)_(2)Co(vtms)](ICy=1,3-dicyclohexylimidazol-2-ylidene,vtms=vinyltrimethylsilane)with primary and secondary hydrosilanes(3 equiv.)furnish the four-coordinate disilyl complexes[trans-(ICy)_(2)Co(SiHRR')_(2)](SiHRR'=SiH_(2)Mes,1;SiH_(2)Ph,2;SiH_(2)Cy,3;SiHPh_(2),4;SiHEt_(2),5)in moderate to good yields.The structures of 1,2 and 4 were established by single-crystal X-ray diffraction.Solution magnetic susceptibility measurement and EPR spectroscopy indicate their low-spin nature(S=1/2).Reactivity studies on 4 led to the establishment of the conversions of 4 to the disilyl dihydride Co(Ⅲ)complex[K(THF)][(ICy)_(2)Co(H)_(2)(SiHPh_(2))_(2)]_n(6)and the fluorosilyl Co(Ⅱ)complex[(ICy)_(2)Co(THF)(SiFPh_(2))][BF_(4)](7)when 4 was treated with excess amount of K and AgBF_(4),respectively,in THF.These conversions hint at the high activity of low-valent and high-valent disilyl cobalt species[trans-(ICy)_(2)Co(SiHPh_(2))_(2)]^(1-)and[trans-(ICy)_(2)Co(SiHPh_(2))_(2)]^(2+).Complex 4 is reactive toward terminal alkynes,but inert toward alkenes and internal alkynes.The reactions of 4 with terminal alkynes CyC≡CH and Me_(3)SiC≡CH(3 equiv.)yield the Co(Ⅱ)complexes[(ICy)_(2)Co(C≡CCy)_(2)](8)and[(ICy)_(2)Co(C≡CSiMe_(3))((SiMe_(3))C=CH_(2))](9),respectively,along with H_(2)SiPh_(2)and alkynylsilanes RC≡CSiHPh_(2)(R=Cy,SiMe_(3)),whereas the reaction with 4-CF_(3)C_(6)H_(4)C≡CH(3 equiv.)produce[(ICy)_(2)Co(C≡CAr)((Ar)C=CH(SiHPh_(2))C=CHAr)](Ar=4-CF_(3)C_(6)H_(4))(10)and H_(2)SiPh_(2).These reactions are proposed to involveσ-bond metathesis reactions between alkyne C(sp)-H bonds and Co-Si bonds in 4.Complexes 6–10 have been characterized by NMR spectroscopy,X-ray diffraction study,and elemental analysis.

Advances in Transition-Metal-Catalyzed Hydrogermylation of Alkenes and Alkynes

Hydrogermylation of alkenes and alkynes provides a straightforward synthetic route to organogermanium compounds that have been found applications in organic synthesis,medicinal chemistry,and material science.This paper reviews the advances in transition-metal-catalyzed hydrogermylation of unsaturated carbon-carbon bonds,including alkenes,alkynes,dienes,and allenes,with the objective of providing readers with the status of the field.Progress,problems,and perspectives in this field are discussed.

Converting carbon dioxide into alkanes via alkane reverse combustion reaction

Energy crisis and environmental degradation are the two most server challenges to modern humane society.Currently,fossil fuels are the main energy resource used by human-beings.The combustion of fossil fuels generates energy and at the same time produces CO_2 and H_2O.Along with the world’s soaring energy consumption,the depleting of fossil fuel resources on earth and the accumulation of the greenhouse gas,CO_2,in atmosphere have raised

Toward improved trade-off between thermoelectric and mechanical performances in polycarbonate/single-walled carbon nanotube composite films

Polymer thermoelectric(TE)composites have witnessed explosive developments in recent years,arising from their promising prospect for lightweight flexible electronics and capability of harvesting waste-heat.In sharp contrast with intrinsically conducting polymers(CPs),the insulating thermoplastics have seldom been employed as the matrices for flexible TE composites despite their advantages of low costs,controllable melt-flowing behaviors and excellent mechanical properties.Here,we report flexible films of polycarbonate/single-walled carbon nanotube(PC/SWCNT)composites with improved trade-off between TE and mechanical performances.The SWCNTs with 1D nanostructure were dramatically aligned by PC melt-flowing under hot-pressing in the radial direction.The composite maximum power factor reaches 4.8±0.8μW m^(−1) K^(−2) at 10 wt%SWCNTs in the aligned direction,which is higher than most previously reported thermoplastics-based TE composites at the same SWCNT loading and even comparable to some intrinsically CPs and their composites.In addition,these composites display significantly higher tensile modulus and strength than CPs and their composites.This study paves an effective way to fabricate flexible films of polymer composites with simultaneously high TE and mechanical performances via judicious alignment of SWCNTs in thermoplastic polymers.

Effects of Spiral Magnetic Field on Structures Transformation and Macrosegregation of Sn-Pb Alloy

The effect of spiral magnetic field （SMF） on the solidification process of Sn-20 wt.%Pb hypoeutectic alloy was studied in this work. The temperature distribution and the macrosegregation together with the eutectic lamellar spacing during solidification were measured under different magnetic fields. The results indicate that the compositions in the top and bottom portions of the sample are nearly the same and the segregation phenomenon is basically eliminated by SMF at an exciting current of 125 A. The morphology of the primary phase transforms from coarse dendrite to rosette or ellipsoidal equiaxed crystal and the spacing of the eutectic lamellar increases from 1.6 to 3.9 μm when the exciting current increases from 0 to 125 A. Moreover, if the exciting current is high enough, the forced fluid flow caused by SMF will enhance the process of transition from lamellar eutectic structure to anomalous rod-like one.

CuZr-based bulk metallic glass and glass matrix composites fabricated by selective laser melting

Monolithic bulk metallic glass and glass matrix composites with a relative density above 98%were produced by processing Cu_(46)Zr_(46)Al_(8)(at.%)via selective laser melting(SLM).Their microstructures and mechanical properties were systematically examined.B2 CuZr nanocrystals(30-100 nm in diameter)are uniformly dispersed in the glassy matrix when SLM is conducted at an intermediate energy input.These B2 CuZr nanocrystals nucleate the oxygen-stabilized big cube phase during a remelting step.The presence of these nanocrystals increases the structural heterogeneity as indirectly revealed by mircrohardness and nanoindentation measurements.The corresponding maps in combination with calorimetric data indicate that the glassy phase is altered by the processing conditions.Despite the formation of crystals and a high overall free volume content,all additively manufactured samples fail at lower stress than the as-cast glass and without any plastic strain.The inherent brittleness is attributed to the presence of relatively large pores and the increased oxygen content after selective laser melting.

Laser additive manufactured high-performance Fe-based composites with unique strengthening structure

Steel matrix composites(SMCs),reinforced by ceramic particles,have received a consistent attention in recent years.Using conventional methods to prepare SMCs is generally challenging,and the mechanical properties of conventionally fabricated SMCs are limited.In this study,we successfully fabricated highperformance SMCs by laser powder bed fusion(LPBF)of a composite powder consisting of Fe-based alloy powder and submicron-sized WC particles.The effect of laser energy density on the phase formation,microstructural evolution,overall density and resulting mechanical properties of LPBF-fabricated composites was investigated.The present results show that a novel Fe_(2)W_(4)C carbidic network precipitates in the solidified microstructure entailing segregations along the boundaries of cellular sub-grains.The presence of this carbidic network hampers the growth of sub-grains even at elevated temperatures,and hence,stabilizes the grain size though prepared at a broad range of different energy densities.The exact distribution of the Fe_(2)W_(4)C carbides depends on the employed laser energy densities,as for instance they are more uniformly distributed at higher energy input.The density of LPBF samples reaches the maximum value of 99.4%at 150 J/mm^(3).In this parameter set,high microhardness of~753 HV,compression strength of~3350 MPa and fracture strain of~24.4%are obtained.The enhanced mechanical properties are ascribed to less metallurgical defects,higher volume fraction of the martensitic phase and increasing pile-up dislocations resulting from the pinning effect by Fe_(2)W_(4)C carbide.