Nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in aerospace community:a comparative analysis

The aerospace community widely uses difficult-to-cut materials,such as titanium alloys,high-temperature alloys,metal/ceramic/polymer matrix composites,hard and brittle materials,and geometrically complex components,such as thin-walled structures,microchannels,and complex surfaces.Mechanical machining is the main material removal process for the vast majority of aerospace components.However,many problems exist,including severe and rapid tool wear,low machining efficiency,and poor surface integrity.Nontraditional energy-assisted mechanical machining is a hybrid process that uses nontraditional energies(vibration,laser,electricity,etc)to improve the machinability of local materials and decrease the burden of mechanical machining.This provides a feasible and promising method to improve the material removal rate and surface quality,reduce process forces,and prolong tool life.However,systematic reviews of this technology are lacking with respect to the current research status and development direction.This paper reviews the recent progress in the nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in the aerospace community.In addition,this paper focuses on the processing principles,material responses under nontraditional energy,resultant forces and temperatures,material removal mechanisms,and applications of these processes,including vibration-,laser-,electric-,magnetic-,chemical-,advanced coolant-,and hybrid nontraditional energy-assisted mechanical machining.Finally,a comprehensive summary of the principles,advantages,and limitations of each hybrid process is provided,and future perspectives on forward design,device development,and sustainability of nontraditional energy-assisted mechanical machining processes are discussed.

High-efficiency forming processes for complex thin-walled titanium alloys components: state-of-the-art and perspectives

Complex thin-walled titanium alloy components play a key role in the aircraft,aerospace and marine industries,offering the advantages of reduced weight and increased thermal resistance.The geometrical complexity,dimensional accuracy and in-service properties are essential to fulfill the high-performance standards required in new transportation systems,which brings new challenges to titanium alloy forming technologies.Traditional forming processes,such as superplastic forming or hot pressing,cannot meet all demands of modern applications due to their limited properties,low productivity and high cost.This has encouraged industry and research groups to develop novel high-efficiency forming processes.Hot gas pressure forming and hot stamping-quenching technologies have been developed for the manufacture of tubular and panel components,and are believed to be the cut-edge processes guaranteeing dimensional accuracy,microstructure and mechanical properties.This article intends to provide a critical review of high-efficiency titanium alloy forming processes,concentrating on latest investigations of controlling dimensional accuracy,microstructure and properties.The advantages and limitations of individual forming process are comprehensively analyzed,through which,future research trends of high-efficiency forming are identified including trends in process integration,processing window design,full cycle and multi-objective optimization.This review aims to provide a guide for researchers and process designers on the manufacture of thin-walled titanium alloy components whilst achieving high dimensional accuracy and satisfying performance properties with high efficiency and low cost.

Mediator complex components are frequent targets for genetic alterations in various types of human cancer

The Mediator co-activator complex is a highly conserved,multisubunit protein complex required for gene transcription by RNA polymerase Ⅱ（RNAPⅡ）in all eukaryotes（Allen and Taatjes,2015）.This complex,which consists of at least 30 polypeptides,can be divided into four structurally distinct sub-modules including the head,middle,tail,and cyclin-dependent kinase 8（CDK8）modules （CKM） （Fig. 1A） （Yin and Wang, 2014; Allen and Taatjes, 2015）.

Magnetorheological finishing of an irregular-shaped small-bore complex component using a small ball-end permanent-magnet polishing head

A novel magnetorheological finishing(MRF)process using a small ball-end permanent-magnet polishing head is proposed,and a four-axes linkage dedicated MRF machine tool is fabricated to achieve the nanofinishing of an irregularψ-shaped small-bore complex component with concave surfaces of a curvature radius less than3 mm.The processing method of the complex component is introduced.Magnetostatic simulation during the entire finishing path is carried out to analyze the material removal characteristics.A typicalψ-shaped small-bore complex component is polished on the developed device,and a fine surface quality is obtained with surface roughness Raof 0.0107μm and surface accuracy of the finished spherical surfaces of 0.3320μm(PV).These findings indicate that the proposed MRF process can perform the nanofinishing of a kind of small-bore complex component with small-curvature-radius concave surfaces.

The Space and Time Features of Global SST Anomalies Studied by Complex Principal Component Analysis

In this paper, the variability characteristics of the global field of sea surface temperature (SST) anomaly are studied by complex principal component (c.p.c.) analysis, whose results are also compared with those of real p.c. analysis. The data consist of 40 years of global SST monthly averages over latitudes from 42 5°S to 67 5°N. In the spatial domain, it is found that the distribution of the first complex loading amplitude is characterized by three areas of large values: the first one in the eastern and central equatorial Pacific Ocean, the second one in the northern tropical Indian Ocean and South China Sea, the third one in the northern Pacific Ocean. As it will be explained, this pattern may be considered as representative of El Nio mode. The first complex loading phase pattern shows a stationary wave in the Pacific (also revealed by real p.c. analysis) superimposed to an oscillating disturbance, propagating from the Pacific to Indian or the opposite way. A subsequent correlation analysis among different spatial points allows revealing disturbances actually propagating westward from the Pacific to the Indian Ocean, which could therefore represent reflected Rossby waves, i.e. the west phase of the signals that propagate disturbances of thermal structure in the tropical Pacific Ocean. In the time domain, a relation between the trend of the first complex principal component and the ENSO cycle is also established.

Collaborative manufacturing technologies of structure shape and surface integrity for complex thin-walled components of aero-engine:Status,challenge and tendency

Presently,the service performance of new-generation high-tech equipment is directly affected by the manufacturing quality of complex thin-walled components.A high-efficiency and quality manufacturing of these complex thin-walled components creates a bottleneck that needs to be solved urgently in machinery manufacturing.To address this problem,the collaborative manufacturing of structure shape and surface integrity has emerged as a new process that can shorten processing cycles,improve machining qualities,and reduce costs.This paper summarises the research status on the material removal mechanism,precision control of structure shape,machined surface integrity control and intelligent process control technology of complex thin-walled components.Numerous solutions and technical approaches are then put forward to solve the critical problems in the high-performance manufacturing of complex thin-wall components.The development status,challenge and tendency of collaborative manufacturing technologies in the high-efficiency and quality manufacturing of complex thin-wall components is also discussed.

A Component Selection Framework of Cohesion and Coupling Metrics

Component-based software engineering is concerned with the develop-ment of software that can satisfy the customer prerequisites through reuse or inde-pendent development.Coupling and cohesion measurements are primarily used to analyse the better software design quality,increase the reliability and reduced system software complexity.The complexity measurement of cohesion and coupling component to analyze the relationship between the component module.In this paper,proposed the component selection framework of Hexa-oval optimization algorithm for selecting the suitable components from the repository.It measures the interface density modules of coupling and cohesion in a modular software sys-tem.This cohesion measurement has been taken into two parameters for analyz-ing the result of complexity,with the help of low cohesion and high cohesion.In coupling measures between the component of inside parameters and outside parameters.Thefinal process of coupling and cohesion,the measured values were used for the average calculation of components parameter.This paper measures the complexity of direct and indirect interaction among the component as well as the proposed algorithm selecting the optimal component for the repository.The better result is observed for high cohesion and low coupling in compo-nent-based software engineering.

MCM3AP,a Novel HBV Integration Site in Hepatocellular Carcinoma and Its Implication in Hepatocarcinogenesis

A novel HBV integration site involved in hepatocarcinogenesis was investigated. The HBV DNA integration sites were detected by Alu-PCR in hepatocellular carcinoma tissues, matched surrounding liver tissues in 30 patients with hepatitis B-related hepatocellular carcinoma (HCC) and 3 cases of normal liver tissues. The integration sites and flanking sequences in human genome were sequenced and blasted, and the expression of integrated HBV genes was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The influence of the up-regulated expression of integrated genes on hepatocarcinogenesis was analyzed. Nineteen integration sites of HBV DNA into HCC tissues were obtained by RT-PCR and sequencing. These genes encoding proteins were: LOC51030, LOC157777, minichromosome maintenance complex component 3 associated protein (MCM3AP), MCTP1, SH3 and multiple ankyrin repeat domains 2 isoform 2, CCDC40, similar to HCG2033532, mitochondrial ribosomal S5 pseudogene 4. One of them was integrated into the intron of MCM3AP. RT-PCR demonstrated that the expression levels of MCM3AP mRNA in HCC tissues, matched surrounding liver tissues and normal liver tissues were in a descendent order. The ratio of MCM3AP mRNA to the GAPDH mRNA in these three tissues was 1.07375, 0.21573, 0.06747 respectively, with the difference being statistically significant among them (P<0.05). Meanwhile, the expression levels of MCM3AP mRNA from HCC tissues in which HBV DNA integrated into MCM3AP were still significantly higher than those without HBV DNA integrated into MCM3AP. It was concluded that the HBV DNA integration sites into human genome were random, and MCM3AP was a new site. The up-regulated MCM3AP mRNA may affect flanking sequences which promote the hepatocarcinogenesis.

Computational implementation of a GIS developed tool for prediction of dynamic ground movement and deformation due to underground extraction sequence

In the last century, there has been a significant development in the evaluation of methods to predict ground movement due to underground extraction. Some remarkable developments in three-dimensional computational methods have been supported in civil engineering, subsidence engineering and mining engineering practice. However, ground movement problem due to mining extraction sequence is effectively four dimensional （4D）. A rational prediction is getting more and more important for long-term underground mining planning. Hence, computer-based analytical methods that realistically simulate spatially distributed time-dependent ground movement process are needed for the reliable long-term underground mining planning to minimize the surface environmental damages. In this research, a new computational system is developed to simulate four-dimensional （4D） ground movement by combining a stochastic medium theory, Knothe time-delay model and geographic information system （GIS） technology. All the calculations are implemented by a computational program, in which the components of GIS are used to fulfill the spatial-temporal analysis model. In this paper a tight coupling strategy based on component object model of GIS technology is used to overcome the problems of complex three-dimensional extraction model and spatial data integration. Moreover, the implementation of computational of the interfaces of the developed tool is described. The GIS based developed tool is validated by two study cases. The developed computational tool and models are achieved within the GIS system so the effective and efficient calculation methodology can be obtained, so the simulation problems of 4D ground movement due to underground mining extraction sequence can be solved by implementation of the developed tool in GIS.

ACCELERATED DISCOVERY AND PROFILING OF PHYSIOLOGICALLY ACTIVE COMPONENTS IN COMPLEX SAMPLES BY HPTLC-EDA-HRMS

On the one hand,the separation of thousands of compounds in a complex extract is thrilling,but may be still be separated unsatisfactorily.Hence,the question arises where to stop in high-sophisticated separation science?Which technical effort is economically justifiable in routine?On the other hand,the separation itself does not imply an effect-directed answer to questions such

Beyond ribosomal function:RPS6 deficiency suppresses cholangiocarcinoma cell growth by disrupting alternative splicing

Cholangiocarcinoma(CCA)is a bile duct malignancy with a dismal prognosis.This study systematically investigated the role of the ribosomal protein S6(RPS6)gene,which is dependent in CCA.We found that RPS6 upregulation in CCA tissues was correlated with a poor prognosis.Functional investigations have shown that alterations in RPS6 expression,both gain-and loss-of function could affect the proliferation of CCA cells.In xenograft tumor models,RPS6 overexpression enhances tumorigenicity,whereas RPS6 silencing reduces it.Integration analysis using RNA-seq and proteomics elucidated downstream signaling pathways of RPS6 depletion by affecting the cell cycle,especially DNA replication.Immunoprecipitation followed by mass spectrometry has identified numerous spliceosome complex proteins associated with RPS6.Transcriptomic profiling revealed that RPS6 affects numerous alternative splicing(AS)events,and combined with RNA immunoprecipitation sequencing,revealed that minichromosome maintenance complex component 7(MCM7)binds to RPS6,which regulates its AS and increases oncogenic activity in CCA.Targeting RPS6 with vivo phosphorodiamidate morpholino oligomer(V-PMO)significantly inhibited the growth of CCA cells,patient-derived organoids,and subcutaneous xenograft tumor.Taken together,the data demonstrate that RPS6 is an oncogenic regulator in CCA and that RPS6-V-PMO could be repositioned as a promising strategy for treating CCA.

Interference and grinding characteristics in ultra-precision grinding of thin-walled complex structural component using a ball-end grinding wheel

As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels,interference is easy to occur.According to screw theory and grinding kinematics,a mathematical model is established to investigate the interference and grinding characteristics of the ball-end wheel.The relationship between grinding wheel inclination angle,C axis rotation angle,grinding position angle and grinding wheel wear are analyzed.As the grinding wheel inclination angle increases,the C axis rotatable range decreases and the grinding position angle increases.The grinding position angle and wheel radius wear show a negative correlation with the C axis rotation angle.Therefore,a trajectory planning criteria for increasing grinding speed as much as possible under the premise of avoiding interference is proposed to design the grinding trajectory.Then grinding point distribution on the ball-end wheel is calculated,and the grinding characteristics,grinding speed and maximum undeformed chip thickness,are investigated.Finally,a complex structural component can be ground without interference,and surface roughness and profile accuracy are improved to 40.2 nm and 0.399 lm,compared with 556 nm and 3.427 lm before ultra-precision grinding.The mathematical model can provide theoretical guidance for the analysis of interference and grinding characteristics in complex components grinding to improve its grinding quality.

Recent developments in plastic forming technology of titanium alloys

Titanium alloys have been used extensively in industry fields including aviation,aerospace and automobile due to their excellent comprehensive properties.Research and development of advanced plastic forming technology are of great importance to manufacturing titanium products of high performance and lightweight with low cost and short cycle.This paper analyzes the development tendencies of titanium alloy forming technology.Recent achievements in precision forming,microstructure control and multi-scale simulation of titanium alloys are reviewed.The forming techniques of large-sale integral complex components are presented.