A Hybrid Approach for Predicting the Remaining Useful Life of Bearings Based on the RReliefF Algorithm and Extreme Learning Machine

Accurately predicting the remaining useful life(RUL)of bearings in mining rotating equipment is vital for mining enterprises.This research aims to distinguish the features associated with the RUL of bearings and propose a prediction model based on these selected features.This study proposes a hybrid predictive model to assess the RUL of rolling element bearings.The proposed model begins with the pre-processing of bearing vibration signals to reconstruct sixty time-domain features.The hybrid model selects relevant features from the sixty time-domain features of the vibration signal by adopting the RReliefF feature selection algorithm.Subsequently,the extreme learning machine(ELM)approach is applied to develop a predictive model of RUL based on the optimal features.The model is trained by optimizing its parameters via the grid search approach.The training datasets are adjusted to make them most suitable for the regression model using the cross-validation method.The proposed hybrid model is analyzed and validated using the vibration data taken from the public XJTU-SY rolling element-bearing database.The comparison is constructed with other traditional models.The experimental test results demonstrated that the proposed approach can predict the RUL of bearings with a reliable degree of accuracy.

Fundamental Perspectives on the Electrochemical Water Applications of Metal-Organic Frameworks

Metal-organic frameworks(MOFs),a family of highly porous materials possessing huge surface areas and feasible chemical tunability,are emerging as critical functional materials to solve the growing challenges associated with energy-water systems,such as water scarcity issues.In this contribution,the roles of MOFs are highlighted in electrochemical-based water applications(i.e.,reactions,sensing,and separations),where MOF-based functional materials exhibit outstanding performances in detecting/removing pollutants,recovering resources,and harvesting energies from different water sources.Compared with the pristine MOFs,the efficiency and/or selectivity can be further enhanced via rational structural modulation of MOFs(e.g.,partial metal substitution)or integration of MOFs with other functional materials(e.g.,metal clusters and reduced graphene oxide).Several key factors/properties that affect the performances of MOF-based materials are also reviewed,including electronic structures,nanoconfined effects,stability,conductivity,and atomic structures.The advancement in the fundamental understanding of these key factors is expected to shed light on the functioning mechanisms of MOFs(e.g.,charge transfer pathways and guest-host interactions),which will subsequently accelerate the integration of precisely designed MOFs into electrochemical architectures to achieve highly effective water remediation with optimized selectivity and long-term stability.

等速节沟道磨削用椭球砂轮设计及优化

为提高等速万向节中星形套椭圆形弧沟道的加工精度,在分析了万向节沟道结构的基础上,提出了一种椭球砂轮磨削星形套沟道的方案,针对此方案,对砂轮尺寸进行了设计计算,初步得到了椭球砂轮的基本尺寸;根据砂轮的实际磨削状态,对砂轮形状进行了结构优化,为验证优化后砂轮形状的正确性,利用UG和VERICUT软件分别对球笼沟道磨床磨削沟道的加工过程和用新型椭球砂轮磨削沟道过程进行了模拟仿真,对比仿真结果,后者误差有所减小,从理论上验证了方案的可行性。

高性能纤维增强树脂基复合材料湿热老化研究进展

高性能纤维增强树脂基复合材料具有卓越的结构整体性及抗分层等特性,在诸多工业领域中具有广泛适用性。在其储藏及使用时,制件强度会不可避免地因湿热老化造成降解和退化。探讨和揭示高性能纤维增强树脂基复合材料在不同湿热老化环境下的力学响应,对其结构件的耐久性、安全服役性能和寿命预估具有至关重要的意义。综述了国内外高性能纤维增强树脂基复合材料湿热老化方面的研究进展,介绍了其吸湿机理以及在湿热环境下的老化机理。梳理了湿热老化环境对于高性能纤维增强树脂基复合材料力学性能的影响,寿命预测模型等。最后指出了高性能纤维增强树脂基复合材料老化研究存在的问题、面临的挑战,对未来研究发展方向提出了展望。

Biomineralization and mineralization using microfluidics:A comparison study

Biomineralization through microbial process has attracted great attention in the field of geotechnical engineering due to its ability to bind granular materials,clog pores,and seal fractures.Although minerals formed by biomineralization are generally the same as that by mineralization,their mechanical behaviors show a significant discrepancy.This study aims to figure out the differences between biomineralization and mineralization processes by visualizing and tracking the formation of minerals using microfluidics.Both biomineralization and mineralization processes occurred in the Y-shaped sandcontaining microchip that mimics the underground sand layers.Images from different areas in the reaction microchannel of microchips were captured to directly compare the distribution of minerals.Crystal size and numbers from different reaction times were measured to quantify the differences between biomineralization and mineralization processes in terms of crystal kinetics.Results showed that the crystals were precipitated in a faster and more uncontrollable manner in the mineralization process than that in the biomineralization process,given that those two processes presented similar precipitation stages.In addition,a more heterogeneous distribution of crystals was observed during the biomineralization process.The precipitation behaviors were further explained by the classical nucleation crystal growth theory.The present microfluidic tests could advance the understanding of biomineralization and provide new insight into the optimization of biocementation technology.

Ataxia telangiectasia-mutated-Rad3-related DNA damage checkpoint signaling pathway triggered by hepatitis B virus infection

AIM: To explore whether acute cellular DNA damage response is induced upon hepatitis B virus (HBV) infection and the effects of the HBV infection.METHODS: We incubated HL7702 hepatocytes with HBV-positive serum,mimicking a natural HBV infection process.We used immunoblotting to evaluate protein expression levels in HBV-infected cells or in non-infected cells; immunofluorescence to show ATR foci ands Chk1 phosphorylation foci formation; flow cytometry to analyze the cell cycle and apoptosis; ultraviolet (UV) radiation and ionizing radiation (IR)-treated cells to mimic DNA damage; and Trypan blue staining to count the viable cells.RESULTS: We found that HBV infection induced an increased steady state of ATR protein and increased phosphorylation of multiple downstream targets including Chk1,p53 and H2AX.In contrast to ATR and its target,the phosphorylated form of ATM at Ser-1981 and its downstream substrate Chk2 phosphorylation at Thr-68 did not visibly increase upon infection.However,the level of Mre11 and p21 were reduced beginning at 0.5 h after HBV-positive serum addition.Also,HBV infection led to transient cell cycle arrest in the S and the G2 phases without accompanying increased apoptosis.Research on cell survival changes upon radiation following HBV infection showed that survival of UV-treated host cells was greatly increased by HBV infection,owing to the reduced apoptosis.Meanwhile,survival of IR-treated host cells was reduced by HBV infection.CONCLUSION: HBV infection activates ATR DNA damage response to replication stress and abrogates the checkpoint signaling controlled by DNA damage response.

LA-ICP-MS in situ analyses of the pyrites in Dongyang gold deposit,Southeast China:Implications to the gold mineralization

The Dongyang gold deposit is a newly discovered epithermal deposit in Fujian Province,Southeast China,along the Circum-Pacific metallogenic belt.Herewith,the authors present mineralogical,scanning electron microscope,and laser ablation inductively coupled clasma mass spectrometry analysis to reveal the relations between Au and Te,As,S,Fe,etc.,and discuss the gold precipitation process.The pyrites in this deposit are Fe-deficient,and are enriched in Te and As.The authors infer that As was mainly in form of As-complexes,and Te-Au-Ag inclusions/solid solution also exsits in the Py I.Along with the depletion of Te and As,they were less active chemically in the Py II,and Au may be incorporated into As-rich and Fe-deficient surface sites by chemisorption onto As-rich growth surfaces.Because of the incorporation of new fluid,Te and As became the most active chemically in the Py III,which was the main elements precipitation stage,and As dominantly substituted for S in the lattice of pyrite,due to the more reducing condition.The authors propose Au was in form of invisible gold,and the incorporation of gold can be considered as post-pyrite event,while the Au-bearing minerals were result of post incorporation of gold in arsenian pyrite.

Development of a micro-indentation device for measuring the mechanical properties of soft materials

Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.

Study on Factors Influencing Urban-rural Dual Economic Structure of Chongqing Based on the State Space Variable Parameter Method

Firstly,this paper reviews and analyzes historic background of urban-rural integration of Chongqing,and the evolution and trend of urban and rural dual economic structure.On the basis of previous researches,it selects factors and variables influencing urban and rural dual economic structure,and establishes an econometric model.By state space Kalman filtering method,it analyzes dynamic influence of factors upon urban-rural dual economic intensity.According to empirical conclusion,it puts forward corresponding policy recommendations for promoting integrated urban and rural economic development of Chongqing.

Research on the ultraweak photon emission from anti-cancer plants

UPE (Ultraweak photon emission) is one kind of a common phenomenon in biological organisms. It contains a wealth of information of biological functions. In this paper, single photon counting system is used to measure UPE of some anti- cancer herbal plants. For the plants, the changes of UPE under different water condition are stud-ied and the varying laws of ultraweak photon number with time are analysed. The results are higher fit double exponential decay law.

基于双目视觉的纬编双轴向壳体复合材料纱线取向检测方法

为保证复合材料构件的性能,实现对预制体成型后构件表面纤维取向的高效检测,本工作基于双目结构光检测技术,开发了一种低成本的复合材料构件表面纱线取向重构系统。首先,标定转台轴线在世界坐标系中的位置;其次,将制备好的样品放置在转台上采集其三维图形信息,提取每次采集结果中经向和纬向纱线的轮廓信息;然后,将处理后的局部数据进行合并,得到样品整体的图形信息及纱线的空间轨迹;最后,评价了系统的纱线轨迹识别覆盖率和图形数据精度,并分析了其误差来源。试验数据显示,重构得到的纱线轨迹覆盖率达到80%,图形数据的误差均不超过0.2%。研究结果表明:设计的双目结构光测量系统是有效可行的,可为产品质量控制和工艺路线设计提供支持。

SULF1作为特发性肺纤维化与肺腺癌共同基因的鉴定及其生物学功能分析

背景和目的特发性肺纤维化(idiopathic pulmonary fibrosis,IPF)是一种原因不明的慢性、进行性、间质性肺疾病,确诊后中位生存期为3-5年。IPF与肺癌风险增加有关。因此,探索IPF和肺腺癌的关键共同致病基因和分子通路,对开发IPF合并肺腺癌的新治疗手段和个性化精准治疗策略的制定具有重要意义。方法利用基因表达综合(Gene Expression Omnibus,GEO)数据库中公开的IPF和肺腺癌基因表达数据集进行生物信息学分析。使用加权基因共表达网络分析识别涉及两种疾病进程的共同基因,进而功能富集分析。随后,联合额外数据集鉴定两种疾病的核心共同基因。并通过癌症基因组图谱计划(The Cancer Genome Atlas,TCGA)数据库和单细胞RNA测序数据集,分析核心共同基因与患者预后的关系,并评估其在肺腺癌中的表达模式、临床相关性、遗传特征和免疫相关功能。最后通过药物数据库筛选出相关的潜在治疗药物。结果两者之间有529个共同致病基因。其中,SULF1作为核心共同致病基因与患者预后不良相关,其在肺腺癌组织中的表达水平显著升高,同时与高突变频率、显著基因组异质性以及抑制性免疫微环境相关。随后的单细胞分析发现SULF1高表达主要源于肿瘤相关成纤维细胞。SULF1表达与肿瘤药物敏感性变化相关,并筛选出与靶向SULF1高表达成纤维细胞相关的潜在小分子药物。结论本研究鉴别出IPF和肺腺癌之间的共同分子途径和核心基因,其中SULF1可能作为两种疾病的潜在生物标志物和治疗靶点。

花键套轴向振动冷挤压成形的微观组织预测模型

为改善花键套冷挤压过程中成形力过大等问题,在冷挤压过程中引入辅助振动,通过仿真实验分析了轴向振动冷挤压的成形结果,并对比了有无振动辅助情况下的微观组织。结果表明,辅助振动冷挤压成形可细化晶粒;为揭示花键套性能与工艺参数间的规律,以振动频率、振动速度幅值和挤压速度作为输入,齿根、齿顶和节圆部位平均晶粒尺寸作为输出,以不同取值下的工艺参数得到的仿真实验数据为基础,利用模糊神经网络建立花键套冷挤压过程中微观组织演化的预测模型,从而建立成形工艺参数与花键套微观组织特征的映射关系。测试集验证结果表明:模型可实现一定范围内较高精度的预测,平均相对误差为6.79%,最大相对误差不超过12%。

基于纳米医学的光热治疗在肿瘤治疗中的研究进展

光热治疗(photothermal therapy,PTT)是一种非侵入性新型肿瘤治疗方式,通过利用光热转换剂(photothermal agent,PTA)在近红外光(near-infrared,NIR)外部光源照射下将光能转换为热能杀伤肿瘤细胞,与传统的手术治疗、放疗、化疗相比,PTT具有靶向性强、不良反应小等优势。快速发展的纳米医学带动了PTA的进步,且PTA作为PTT产生作用的核心部件,其水溶性、生物安全性、光热转换效率等特性直接影响了PTT的效果。此外,PTT还可以联合化疗、光动力治疗、基因治疗和免疫治疗协同治疗肿瘤。本文对PTA进行总结,并就PTT在肿瘤领域的研究进展进行综述。

Nonlinear regression model for peak-failure strength of rockfill materials in general stress space

A nonlinear regression model for peak-failure strength prediction of rockfill materials is proposed. It is based on the relationship between the peak-failure stress ratio and the normalized confining pressure as well as the relationship between the normalized peak-failure stress ratio and the exponent function of the intermediate principal stress ratio. This model can well predict the variations of the peak-failure stress ratio with the initial confining pressure and the intermediate principal stress ratio for different rockfill materials under different general stress paths. Comparisons of the measured and predicted results show that the peak-failure strength under the constant-p' and constant-b path is larger than that under the constant-σ'_3 and constant-b path. The predictive capacity of the proposed model for the peakfailure stress ratio is better than that for the peak-failure friction angle.

Simultaneous Detection and Removal of Formaldehyde at Room Temperature: Janus Au@ZnO@ZIF-8 Nanoparticles

The detection and removal of volatile organic compounds(VOCs) are of great importance to reduce the risk of indoor air quality concerns. This study reports the rational synthesis of a dual-functional Janus nanostructure and its feasibility for simultaneous detection and removal of VOCs.The Janus nanostructure was synthesized via an anisotropic growth method, composed of plasmonic nanoparticles,semiconductors, and metal organic frameworks(e.g.,Au@ZnO@ZIF-8). It exhibits excellent selective detection to formaldehyde(HCHO, as a representative VOC) at room temperature over a wide range of concentrations(from 0.25 to100 ppm), even in the presence of water and toluene molecules as interferences. In addition, HCHO was also found to be partially oxidized into non-toxic formic acid simultaneously with detection. The mechanism underlying this technology was unraveled by both experimental measurements and theoretical calculations: ZnO maintains the conductivity, while ZIF-8 improves the selective gas adsorption; the plasmonic effect of Au nanorods enhances the visible-light-driven photocatalysis of ZnO at room temperature.

基于线圈面积的罗纹织物半球成形研究

为研究纬编轴向织物的成形性能,分别采用芳纶、涤纶和超高分子量聚乙烯纱线在手摇横机上编织1+1罗纹织物,并铺覆在不同直径的半球上,测量织物试样在不同直径半球的不同高度上局部线圈面积的变化情况,探讨纱线自身力学性能、织物成形高度及球体直径对织物局部线圈面积变化的影响。结果表明,纱线的弯曲性能越好,在相同直径的球体上,织物局部线圈的相对面积变化越小;成形球体直径越大,织物局部线圈的相对面积变化越小;同一织物在同一半球体上,织物局部线圈的面积变化不均匀,与成形高度相关。该研究有助于纬编轴向织物三维成形的理论研究。

Parametric study on mass loss of penetrators

Earth penetration weapon （EPW） is applicable for attacking underground targets protected by reinforced concrete and rocks. With increasing impact velocity, the mass loss/abrasion of penetrator increases, which significandy decreases the penetration efficiency due to the change of nose shape. The abrasion may induce instability of the penetrator, and lead to failure of its structure. A common disadvantage, i.e. dependence on corresponding experimen- tal results, exists in all the available formulae, which limits their ranges of application in estimating the mass loss of penetrator. In this paper, we conduct a parametric study on the mass loss of penetrator, and indicate that the mass loss of penetrator can be determined by seven variables, i.e., the initial impact velocity, initial nose shape, melting heat, shank diameter of projectile and density and strength of target as well as the aggregate hardness of target. Further discussion on factors dominant in the mass abrasion of penetrator are given, which may be helpful for optimizing the target or the projectile for defensive or offensive objectives, respectively.

Breviscapine reduces neuronal injury caused by traumatic brain injury insult:partly associated with suppression of interleukin-6 expression

Breviscapine,extracted from the herb Erigeron breviscapus,is widely used for the treatment of cardiovascular diseases,cerebral infarct,and stroke,but its mechanism of action remains unclear.This study established a rat model of traumatic brain injury induced by controlled cortical impact,and injected 75 μg breviscapine via the right lateral ventricle.We found that breviscapine significantly improved neurobehavioral dysfunction at 6 and 9 days after injection.Meanwhile,interleukin-6 expression was markedly down-regulated following breviscapine treatment.Our results suggest that breviscapine is effective in promoting neurological behavior after traumatic brain injury and the underlying molecular mechanism may be associated with the suppression of interleukin-6.