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A physical model for acoustic resonance in the annular cavity structure is developed to represent the typical characteristic when acoustic resonance occurs. Firstly, the measurement of sound pressure in the casing and rotor blades vibration is operated in a multistage high pressure compressor. The sharp peak frequency and discrete multi-tone occur in the frequency spectrum of sound pressure in the compressor, and the vibration of the first stage of rotor blades synchronously presents the high amplitude. The frequencies associated with rotor blades vibration can be calculated with rotating sound source theory. It is also confirmed that acoustic resonance occurs in the multistage compressor. With acoustic similarity principle, an annular cavity model is established to simulate the typical characteristics of acoustic resonance in the compressor based on Large Eddy Simulation (LES) and Lighthill acoustic analogy. The coupling relationship between cavity acoustic mode and disc vibration mode shape is expounded when acoustic resonance occurs in the model. And acoustic resonance will be locked in the certain flow rate range. All these characteristics match well with those occur in the multistage high pressure compressor.

Rotor blades fault of aeroengine compressor is mostly caused by mechanical and aerodynamic excitation. And the excitation factor of high intensity sound wave to rotor blades should not be ignored. Experimental researches are conducted on a multistage high pressure compressor. When high level vibration occurs on the first stage of rotor blades, the noise spectrum presents typical characteristic for discrete multi-tone in the compressor. The amplitude of blade vibration displacement and the sound pressure level of characteristic frequency noise increases and decreases simultaneously and reaches the maximum value at the same time. This frequency merely occur on a certain speed range and is locked in a specific range which presents no variation with the rotating speed. When high level vibration occurs on the first stage of rotor blades, the noise spectrum presents a sharp peak and the propagation state of the characteristic frequency is a helix structure in the compressor. It can be confirmed that acoustic resonance occurs in the multistage compressor. The acoustic resonance frequency and its side band frequencies are generated by modulation of a rotating noise source at the rotor speed which is the excitation source of the rotor blades vibration. Keywords: Acoustic resonance, Blades vibration, Characteristic frequency, Multistage compressor, Source identification

A finite element model of the cantilever combined support rotor included two discs established in this paper to predict and explain the nonlinear vibration phenomenon. The model considered local nonlinear support force generated by the combined support and the coupling effects of the rotor with the combined support. The nonlinear factors contained the clearance, the Hertz contact force and the vibration of the rolling bearing and the nonlinear force of the squeeze film damper. The combined support included bearing, squeeze film damper and squirrel cage elastic support. Finally, the high-dimensional partial differential equations with local nonlinearity were derived and solved by Newmark- $$\upbeta $$ combined with Runge–Kutta method. Based on the above theoretical results, the bifurcation phenomenon of vibration response at different positions was analysed and the dynamic response of the rotor system at different positions due to the rotational speed was compared.

This study investigates the determination approach of distorted scaling laws for predicting the dynamic characteristic of an aero engine’s blisk. Based on the dynamic scaling laws of typical thin-w...

A long-span hybrid grid hangar structure and a modeling method for the long-span hybrid grid hangar structure based on the principle of leverage are proposed in this paper. Based on the SAP2000 spatial structure design software, the C# language was used to develop a plug-in to automatically create a long-span hybrid grid structure based on the principle of leverage, which realized the automatic generation by inputting parameters such as the span of the hangar structure, the number of horizontal grids, and the number of vertical grids. The optimization design method of the long-span hybrid grid structure based on particle swarm algorithm is proposed. SAP2000 software is used and the C# language is used to develop the optimization design program of the long-span hybrid grid structure based on the principle of leverage. The optimization design is carried out, and the optimization results show that the program can reduce the thickness of the roof and reduce the vertical displacement at the opening of the hangar roof on the basis of meeting the current specifications.

The Chongqing-Hubei back-to-back flexible HVDC transmission project has operated for over one year. The importance of its operation, maintenance, system commissioning, and fault analysis are increasing continuously. It is necessary to build an operation support platform that support its routine works. In this paper, a real-time digital simulation operation support platform for this project is established based on RT-LAB. The simulation of some key commissioning tests and fault analysis in the Chongqing-Hubei project is simulated, and the simulation results are verified according to the comparison with the waveform recording of actual commissioning and fault. The platform can be used for operation, maintenance and commissioning planning, and also for studies on the control & protection principles, faults analysis of flexible DC transmission project.

The present study aimed to determine whether maslinic acid effectively inhibits the proliferation of MKN28 cells, and to investigate the mechanisms underlying its antitumor functions. MKN28 cell viability was evaluated using a Cell Counting Kit-8, cell proliferation was analyzed by a colony formation assay and flow cytometry was used to investigate the rate of apoptosis. Western blot analysis was performed in order to determine the differential expression levels of Janus kinase (JAK), signal transducer and activator of transcription 3 (STAT3) and apoptosis associated proteins B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax) and Bcl-2 associated agonist of cell death (Bad). Interleukin-6 (IL-6) concentration was evaluated using ELISA. IL-6 and anti-IL-6 antibodies were used to investigate the role of IL-6 in MKN28 cells treated with maslinic acid proliferation, and the STAT3 phosphorylation rates. The results demonstrated that maslinic acid treatment significantly reduced cell proliferation, induced apoptosis and was accompanied by a significant decrease in Bcl-2, Bax and Bad expression levels. Maslinic acid treatment also resulted in the downregulation of phosphorylated-STAT3 and JAK2, and significantly inhibited the protein expression of IL-6. Maslinic acid is able to inhibit MKN28 cell proliferation and the phosphorylation of STAT3 by downregulating the expression of IL-6. These results suggest that maslinic acid suppresses the growth of MKN28 cells by inducing apoptosis via its inhibition of the IL-6/JAK/STAT3 signaling cascade.

A Jeffcott rotor system with surface coatings capable of describing the mechanical vibration resulting from unbalance and rub-impact is formulated in this article. A contact force model proposed recently to describe the impact force between the disc and casing with coatings is employed to do the dynamic analysis for the rotor system with rubbing fault. Due to the variation of penetration, the contact force model is correspondingly modified. Meanwhile, the Coulomb friction model is applied to simulate the friction characteristics. Then, the case study of rub-impact with surface coatings is simulated by the Runge-Kutta method, in which a linear interpolation method is adopted to predict the rubbing instant. Moreover, the dynamic characteristics of the rotor system with surface coatings are analyzed in terms of bifurcation plot, waveform, whirl orbit, Poincare map and spectrum plot. And the effects of the hardness of surface coatings on the response are investigated as well. Finally, compared with the classical models, the modified contact force model is shown to be more suitable to solve the rub-impact of aero-engine with surface coatings.

Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achievements of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.

Novel targeted therapies need to be developed for gastric cancer, the third most common cancer type and the second most common cause of cancer-related mortality in China. Previous studies indicate that angiopoietin (Ang)-2 serves a role in the proliferation, migration, invasion and adhesion of malignant cells. The present study identified, using functional studies, that exogenous expression of miR-218 increased migration of NCI-87 and HGC-27 gastric cancer cells, which coincided with a reduction in the expression of Ang-2. In addition, intratumoral delivery of miR-218 inhibited proliferation and angiogenesis of gastric cancer cells in vivo, with a corresponding decreased in Ang-2 expression. These results indicate that miR-218 serves an important role in gastric cancer tumorigenesis through regulating the expression of Ang-2. Therefore, components of miR-218/Ang-2 signaling could provide novel therapeutic targets for the treatment of gastric cancer.

A dual-rotor system dynamics model is established for simulating the aero-engine vibration with unbalance-partial rubbing coupled faults. The main characteristics of the dual-rotor model are as follows: (1) the compressor disc and turbine disc are considered in both low pressure rotor and high pressure rotor; (2) two eccentricities exist in the LP and HP turbine discs, respectively; (3) two convex points exist in the casing and then fixed-point rubbing may occur in the LP and HP turbine discs, respectively; (4) coatings are painted on the surfaces of all the discs and casing. Taking into account the soften characteristics of coatings, the Lankarani-Nikravesh model is used to describe the impact forces between two convex points and two turbine discs. Then, the case of two fixed-point rubbings is simulated by the Runge-Kutta method. At different rotational speeds, the responses of the dual-rotor system are analyzed by spectrum cascades and waveforms. Meanwhile, the effects of rotational speed ratio, initial clearance and curvature radius of convex point on the dynamic characteristics and impact force are discussed. Finally, the experiment performed on a dual-rotor test rig proves the validity of the dynamics model.

For theoretical and experimental research on the fixed point rubbing of aero-engine, a dual-rotor system capable of describing the mechanical vibration resulting from two imbalances and fixed point rubbing is established in this paper. Considering the effects of the softer coatings painted on the discs and casing, the Lankarani–Nikravesh model is applied to describe the impact force between the compressor disc of the low pressure rotor and the casing convex point. Meanwhile, the Coulomb model is used to simulate the frictional characteristics. Then the motion equations of the dual-rotor system with fixed point rubbing are solved by the Runge–Kutta method and the complicated responses at different rotational speeds are analyzed by the 3D waterfall plot, waveform and frequency spectrum. To verify the effectiveness of the dual-rotor system dynamic model, the experiment of fixed point rubbing is performed on a dual-rotor test rig. The vibration displacement of the low pressure rotor is obtained from the data measured in the impact experiment. The numerical results and experimental results indicate that for the dual-rotor system without rub-impact, the phenomena of beat vibration occur at the certain rotational speed ratio. Moreover, for the case of fixed point rubbing, several combination frequencies in the responses of the dual-rotor system are identified as the particular fault frequencies.

Rotor unbalance and rub-impact are major concerns in rotating machinery. In order to study the dynamic characteristics of these machinery faults, a dual-disc rotor system capable of describing the mechanical vibration resulting from multi-unbalances and multi-fixed-point rub-impact faults is formulated using Euler beam element. The Lankarani–Nikravesh model is used to describe the nonlinear impact forces between discs and casing convex points, and the Coulomb model is applied to simulate the frictional characteristics. To predict the moment of rub-impact happening, a linear interpolation method is carried out in the numerical simulation. The coupling equations are numerically solved using a combination of the linear interpolation method and the Runge–Kutta method. Then, the dynamic behaviours of the rotor system are analysed by the bifurcation diagram, whirl orbit, Poincare map and spectrum plot. The effects of rotating speed, phase difference of unbalances, convex point of casing and initial clearance on the responses are investigated in detail. The numerical results reveal that a variety of motion types are found, such as periodic, multi-periodic and quasi-periodic motions. Moreover, the energy transfer between the compressor disc and the turbine disc occurs in the multi-fixed-point rubbing faults. Compared with the parameters of the turbine disc, those of the compressor disc can affect the motion of the rotor system more significantly. That is, the responses exhibit simple 1T-periodic motion in the wide range of rotating speed under the conditions of sharp convex point and larger initial clearance. These forms of dynamic characteristics can be effectively used to diagnose the fixed-point rub-impact faults.

A novel hysteretic force model is proposed to describe the contact force for the impact analysis of the rotor blade and casing of an aero-engine in this article. Firstly, the structural stiffness of both the flexible blade and casing, as well as the local stiffness of coating painted on both the blade tip and casing are taken into consideration in the formulation of the impact stiffness. Moreover, energy loss during the process of impact is expressed by introducing the nonlinear hysteretic damping. Then, the hysteretic impact force model for both soft and hard coating is obtained. In order to estimate the values of parameters in the contact force model and show the effectiveness of the model, impact experiments are performed at different rotating speeds on a rotor test rig. The impact force and the displacement at the contact point are obtained from the data measured in the experiment. According to the theory of the least square method, the ranges of curvature radius and coefficient of restitution are given respectively. At different rotating speed in certain range, simulation results are compared with the actual experimental results to illustrate the validity and accuracy of the contact force model.

In this study, we investigate the dynamic scaling laws of geometrically distorted models for predicting dynamic characteristics of thin-walled short cylindrical shells. Approximate and accurate analysis methods for obtaining the scaling laws are introduced. Two coefficient functions are established in deriving high-order scaling laws for a narrow range distorted model. Then a modified function is obtained by using numerical analysis, in order to modify the errors of wide range distorted models. The general form of the high-order scaling laws of thin-walled short cylindrical shells is also developed. To be practical, a process of detecting scaling laws by experimental operation is summarized, and the applicability of scaling laws is validated by using experimental data. Although there are some limitations in practice, the scaling laws of the thin-walled short cylindrical shell still have the ability to predict the prototype with good accuracy.

In designing the test model of thin-walled cylindrical shells, geometrically distorted models are widely used. This study investigates a method of designing a distorted cylindrical shell model by considering the strength requirement, which means the test model should reflect the strength situation or even failures of the prototype. The significance of this study is that it provides an acceptable process which guides the design of test models. First, governing equations are employed to derive the scaling law of the natural frequency. The harmonic response is calculated in order to obtain the scaling law of the vibration response amplitude. As the study is based on governing equations of elastic cylindrical shells, only elastic behavior is discussed. Then considering the different materials’ ultimate stress, an excitation force ratio is defined. An applicable size interval is investigated and the range of the excitation force is obtained. Finally, an aluminium alloy cylindrical shell is used as a prototype and a NO. 45 steel scaled down cylindrical shell is used as a distorted test model. The accuracy of the prediction is verified by using simulation data.

A novel method of aero-engine rubbing positions identification based on cepstrum analysis is proposed, and the transfer path characteristics which reflect the transfer characteristics information from rubbing points to casing measuring points are separated from the vibration acceleration signals of casing by means of cepstrum analysis. Therefore, there is different transfer characteristics information at different rubbing positions, and in view of this, twenty rubbing positions identification features from the cepstrum are extracted. A large number of rubbing experiments of different positions are simulated with the rotor experiment rig of aero-engine, and the characteristic analysis of experimental samples at different rubbing positions is carried out, and the results indicate the consistency of features to the same rubbing position and the difference of the features to the different rubbing positions. Finally, the aero-engine rubbing positions identification is carried out using the nearest neighbor classification method, the recognition rate reaches 100%, and the effectiveness of the method is full verified.

e15515 Background: Apatinib, a small molecule tyrosine kinase inhibitor, has been approved to use in patients with advanced gastric adenocarcinoma or gastroesophageal junction adenocarcinoma after at least two systemic chemotherapy regimens in China. This study aims to observe the efficacy and safety of apatinib in real word clinical practice and preliminarily explore the characteristics of population with more clinical benefit. Methods: This study included patients with non-operative or advanced gastric cancer confirmed by histopathology or cytology, and did not intervene the regimen which was entirely determined by the clinicians and patients. Results: From April 16, 2018 to January 12, 2019, 732 patients enrolled, and all patients had been followed up at least once. Total 342 patients were eligible for efficacy evaluation. Among them, 43 patients achieved partial response (PR), 209 patients achieved stable disease (SD) and 90 patients experienced progression disease (PD). The overall response rate (ORR) was 12.55%, and the disease control rate was 73.6%. The mPFS have not yet reached. For patients ≥65 years, the ORR was 26.32%, and for patients < 65 years, ORR was 8.33%. For patients with non-signet ring cell carcinoma and signet ring cell carcinoma, the ORRs were 15.22% and 6.0%. For patients with and without organ metastasis, the ORRs were 15.25% and 3.75% respectively. The PFS analysis showed that, Combined chemotherapy and age > 65 may predict longer PFS. The OS analysis showed that, ECOG 0-1, combined chemotherapy, AFP positive and male predict longer OS. The overall incidence of adverse events was 84%. The most common adverse events were hypertension (28.8%), fatigue (22.4%), hand-foot syndrome (17.3%), anorexia (12.8%) and nausea (10.5%). Conclusions: Apatinib showed promising antitumor activity in patients with non- operable or advanced Gastric Cancer in this real word study. The prolonging survival benefits maybe could be attenuated by age 1, treatment regimen, normal AFP, and pathological diagnosis of non-signet ring cell carcinoma. Clinical trial information: ChiCTR1800015701.

In the present study, a new method of predicting the dynamic behavior of a variable thickness (VT) cantilever plate by using a thin plate scaled model is proposed. The thin plate model, defined as the model thin (MT) plate, is designed by using the newly proposed similitude design method. The method is derived based on the transfer matrix of both the stepped thickness (ST) plate that is simplified by the VT plate and the thin plate. The thickness of the MT plate is calculated by introducing the equivalent thickness corresponding to each VT plate’s vibration modals, such that a series of accurate distorted scaling laws are provided to predict each corresponding property. Moreover, an algorithm of designing the MT plate is proposed and a design process is summarized in steps. Finally, an example, where the prototype VT plate is made of 42 CrMo and the MT plate is made of NO. 45 steel, is discussed to validate the proposed design method, showing that the MT plate, which is designed by using the proposed method, can accurately predict the dynamic properties of the prototype VT plate, and showing its significance in engineering practice.

This study investigates new dynamic scaling laws of geometrically distorted models in predicting the dynamic characteristics of a cantilever plate. The significance of this study is to provide new scaling laws and rules for selecting dynamic scaling laws, which guide the design of distorted models. By considering the size effect of different orders’ vibration, a governing equation and the method of sensitivity analysis are employed to establish dynamic scaling laws between the model and the prototype. Both approximate and accurate scaling laws are investigated and the processes for determining these scaling laws are summarized. After that, a commonly used titanium alloy plate is analyzed as a prototype to compare the accuracy of the approximate scaling laws and the accurate scaling laws. Finally, the applicability of these new scaling laws is validated by experimental data. The results indicate that, by using the new scaling laws, the distorted models can predict the characteristics of the titaniu...

For the applicability of dynamic similitude models of thin walled structures, such as engine blades, turbine discs, and cylindrical shells, the dynamic similitude design of typical thin walled structures is investigated. The governing equation of typical thin walled structures is firstly unified, which guides to establishing dynamic scaling laws of typical thin walled structures. Based on the governing equation, geometrically complete scaling law of the typical thin walled structure is derived. In order to determine accurate distorted scaling laws of typical thin walled structures, three principles are proposed and theoretically proved by combining the sensitivity analysis and governing equation. Taking the thin walled annular plate as an example, geometrically complete and distorted scaling laws can be obtained based on the principles of determining dynamic scaling laws. Furthermore, the previous five orders’ accurate distorted scaling laws of thin walled annular plates are presented and numerically validated. Finally, the effectiveness of the similitude design method is validated by experimental annular plates.

Li, G., Cheng, P., Wang, D., Batten, D. J. (2009). The spinicaudatan Tylestheria and biostratigraphic significance for the age of dinosaur eggs in the Upper Cretaceous Majiacun Formation, Xixia Basin, Henan Province, China. Cretaceous Research, 30 (2), 477-482.

Reforming the teaching mode of fundamental chemistry experiment (FCE) course is important to realize the teaching target—cultivating the creative talents in the universities and colleges. For this goal, several measures are suggested in this paper: These measures involve “reforming the teaching contents, standing out the application and innovation; “reforming the teaching method, strengthening the students innovation abilities” and “focusing on the development of comprehensive quality, improving the evaluation system of the FCE course. The practice of these methods achieved significant effects in correcting and changing the student's attitudes to experiment, increasing the student's experiment ability and cultivating the the student's good scientific style. Keywordsreform, fundamental chemistry experiment; teaching mode, basic chemistry experiment; innovation

This study investigates a method of designing a simplified cylindrical shell model. This model accurately predicts the dynamic characteristics of a prototype cylindrical shell with sealing teeth accurately. The significance of this study is that it provides an acceptable process which guides the design of test models. Firstly, an equivalent cylindrical shell with rectangular rings is designed by combining the energy equation and numerical analysis. Then the transfer matrixes of the stiffened cylindrical shell and the cylindrical shell are employed to calculate the equivalent thickness of the simplified cylindrical shell commonly used in model tests. Further, the equivalent thicknesses are normalized by introducing an average equivalent thickness. The distorted scaling laws and size applicable intervals are investigated to reduce the errors caused by the normalization. Finally, a 42CrMo cylindrical shell with sealing teeth is used as a prototype and a number 45 steel scaled-down cylindrical shell is used as a distorted test model. The accuracy of the prediction is verified by using experimental data, and the results indicate that the distorted model can predict the characteristics of the stiffened cylindrical shell prototype with good accuracy.

China's Liaohe Oilfield is the country's largest heavy oil field and contains numerous smaller, individually named, reservoirs (oilfields) with oil viscosity ranging from 100 cp to over 50,000 cp. Because of pressure depletion, steam huff-n-puff (cyclic steam) has reached its economic limit in a number of the heavy oil reservoirs in Liaohe. Recently, a flue (exhaust) gas-steam slug process has been tested in an attempt to improve recovery of medium heavy oil, oil with a viscosity less than 1,000 cp. Pilot tests, which started in September 1998, used one injection well and 9 production wells. The pilot test conducted in the eastern part of Block Du-66 of Shuguang Oilfield showed encouraging results. Average oil production increased from 1.8 t/d before the test to 20 t/d after more than 65 days production, with a peak oil rate of 29.2 t/d. The water-cut dropped from 84% to 39%. Drop in watercut reduced operating and water disposal costs. Cost of the entire operation of the flue gas-steam is about half of the cost of steam generated by a boiler. This paper describes the design, construction and operation of gas-steam slug project. The economics of the project and success to date are encouraging. This has prompted application of the gas-steam process to recover lower viscosity heavy oil from other Chinese reservoirs.