三旋轮缩旋时金属变形规律研究

利用三旋轮自动错距旋压机对管坯进行缩旋成形实验，分别研究了缩径量和旋压道次等工艺参数对缩旋成形的影响规律，并探讨了其变形机理．结果表明，三旋轮缩旋时变形区坯料的壁厚减薄，轴向长度增加．壁厚减薄量与总的缩径量成正比．在缩径量相同的条件下，旋压道次增多，坯料壁厚减薄的程度也增大．

流动缩旋紫铜筒体的试验分析

此文论述了紫铜结晶简休流动缩旋成形的试验过程.采用流动旋压缩旋筒形件的试验研究,实现了以减径为主的缩谈成形,旋出了满足紫铜结晶器精加工要求的大直径厚壁筒体.通过利用三向投影接触面积和三向旋压分力的计算分析,并与变薄旋压变形相比较,对流动缩旋有了一定的了解,探讨了流动旋压方式进行普通旋压变形的工艺过程.

三旋轮缩旋变形实验研究

实验研究了三旋轮缩旋的变形规律，研究结果表明，缩旋时坯料壁厚减薄，轴向长度增加，壁厚减薄量与总的缩径量成正比，在缩径量相同的条件下，旋压次数增多，坯料壁厚减薄的程度也增大。

微小型薄壁铜管旋锻缩径工艺锻打频率的研究

通过研究薄壁铜管旋锻缩径工艺的成形机理,建立了相应的运动学模型,推导了锻打频率以及最大进给速度和进给力的计算公式。利用有限元分析软件MSC.MARC建立了薄壁铜管旋锻缩径的有限元模型,对其成形过程进行模拟计算,获得不同工艺参数下的成形特征,并分析锻打频率对薄壁铜管旋锻缩径成形的影响规律。同时对旋锻缩径过程进行了实验研究分析,讨论了锻打频率对铜管成形质量的影响。有限元模拟和实验结果均表明提高锻打频率有利于提高进给速度和进给力,改善成形缺陷。而锻打频率的误差通过测量主轴转速计算得到,验证了计算公式的正确性。

薄壁铜管旋锻缩径工艺形变规律研究

薄壁铜管在旋锻缩径过程中成形表面易产生凹陷、屈曲等缺陷。为获得良好的缩径表面成形质量,论文通过理论分析,获取旋锻缩径过程中旋锻模具运动曲线规律;依据相邻锻打周期内旋锻模具与铜管接触关系,研究工艺参数与铜管表面产生缺陷的关系;采用ABAQUS软件建立四片式模具锻打模型,分析进给速度对薄壁烧结态铜管缩径成形质量的影响规律。结果表明:增加旋锻模具数量可以提高缩径表面成形质量;管壁越薄越不利于获得高的表面成形质量;提高进给速度,旋锻缩径过程中铜管缩径表面更容易产生凹陷或屈曲等缺陷。

关于贲巴瓶

贲巴瓶的“贲巴”,作本巴。藏语音译,意为‘瓶’。”因此,这一名词实质上就是指一种瓶。 就所见到的贲巴瓶来说,造型基本一致,有有嘴无嘴之分。除去嘴的部分,全器看去颇似一个小型喇嘛塔:瓶底为塔底,腹部为半圆形覆钵,颈部为塔刹,口部为华盖。《饮流斋说瓷》一书中说:塔瓶“口哆而平,项数折至腹,圆而不甚巨,胫略缩旋开至足,略如平顶之塔形,故号塔瓶也。乾隆始有此制……”可知塔瓶即贲巴瓶。

Improved SDT Process Data Compression Algorithm

Process data compression and trending are essential for improving control system performances. Swing Door Trending (SDT) algorithm is well designed to adapt the process trend while retaining the merit of simplicity. But it cannot handle outliers and adapt to the fluctuations of actual data. An Improved SDT (ISDT) algorithm is proposed in this paper. The effectiveness and applicability of the ISDT algorithm are demonstrated by computations on both synthetic and real process data. By applying an adaptive recording limit as well as outliers-detecting rules, a higher compression ratio is achieved and outliers are identified and eliminated. The fidelity of the algorithm is also improved. It can be used both in online and batch mode, and integrated into existing software packages without change.

Study on Airflow Field of Condensing Zone in Compact Spinning System with Perforated Drum

Negative pressure plays a very important role in compact spinning system.To know airflow field and its distribution is helpful to look into the condensing principle of fiber bundle.Therefore,computational fluid dynamics(CFD)software was used to simulate airflow field in this paper.Airflow velocity distributions both in different fiber layers and under different negative pressures were discussed.The results indicate that airflow velocity in upper layer of the fiber bundle is greater than that in lower layer.Airflow velocities in both X and Y axis directions have a positive correlation with negative pressure.It can provide a theoretical base to make high quality compact yarns in productive practice.

Extraction of P-and S-wave angle-domain common-image gathers based on first-order velocity-dilatation-rotation equations

Accuracy of angle-domain common-image gathers(ADCIGs)is the key to multiwave AVA inversion and migration velocity analysis,and of which Poynting vectors of pure P-and S-wave are the decisive factors in obtaining multi-component seismic data ADCIGs.A Poynting vector can be obtained from conventional velocity-stress elastic wave equations,but it focused on the propagation direction of mixed P-and S-wave fields,and neither on the propagation direction of the P-wave nor the direction of the S-wave.The Poynting vectors of pure P-or pure S-wave can be calculated from first-order velocity-dilatation-rotation equations.This study presents a method of extracting ADCIGs based on first order velocitydilatation-rotation elastic wave equations reverse-time migration algorithm.The method is as follows:calculating the pure P-wave Poynting vector of source and receiver wavefields by multiplication of P-wave particle-velocity vector and dilatation scalar,calculating the pure S-wave Poynting vector by vector multiplying S-wave particle-velocity vector and rotation vector,selecting the Poynting vector at the time of maximum P-wave energy of source wavefield as the propagation direction of incident P-wave,and obtaining the reflected P-wave(or converted S-wave)propagation direction of the receiver wavefield by the Poynting vector at the time of maximum P-(S-)wave energy in each grid point.Then,the P-wave incident angle is computed by the two propagation directions.Thus,the P-and S-wave ADGICs can obtained Numerical tests show that the proposed method can accurately compute the propagation direction and incident angle of the source and receiver wavefields,thereby achieving high-precision extraction of P-and S-wave ADGICs.

Additional Twists of Yarn Produced by System of Compact Spinning with Lattice Apron

Based on the flow simulation in the condensing zone of compact spinning with lattice apron and a bead-elastic rod dynamic model of the flexible fiber,trajectories of fibers with different negative pressure are simulated by specially designed Matlab procedure.Then displacement components of fibers at YZ profile under different negative pressure conditions are extracted and compared.The results show that the fibers of different initial positions gradually converge,and are interlaced for position change in yarn cross-section,caused by the airflow in the condensing zone.Finally,compact-spun yarn with different negative pressure and conventional ring spun yarn are produced and their twists are tested.Both the results of simulation and experiments illustrate the existence of additional twists.Also the relationship between additional twists and negative pressure is verified.

Aerodynamic performance of high-turning curved compressor cascade with boundary layer suction

The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.

Quantum Collapse and Revival of Atom in Mode-Mode Competing System

The atomic inversion dynamics in the mode-mode competing system is studied bymeans of fully quantum theory. A general solution to the Schroedinger equation of this system isobtained. The influence of the relative competing strength between the atom and the two-mode Geld onthe atomic inversion is disccussed. We show that the presence of the mode-mode competition canresult in periodical collapses-revivals of the atomic inversion.

Simulation and Analysis of Fiber Motion in Condensing Zone of Compact Spinning with Lattice Apron

To get fiber motion in condensing zone of compact spinning,velocity of this area is achieved by simulation,and then a bead-elastic rod fiber model is established.Based on simulation and dynamic analysis on this zone,governing equations are constructed and Runge-Kutta approach is used.Lastly,trajectories of fibers are calculated by specially designed Matlab procedure according to the principles mentioned above.Results show that fiber motions at different initial positions are different;X-axis velocity component makes fibers gathering on sides of suction slot;Y-axis airflow gets fibers gradually close and then stick to the surface of lattice apron.Fiber motions also reflect that the compact spinning process in condensing zone can be divided into three parts:fast convergence zone,adjustment convergence zone,and steady convergence zone.

Subtransus deformation mechanisms of TC11 titanium alloy with lamellar structure

Isothermal compression tests are applied to study the deformation mechanisms of TCll titanium alloy with lamellar structure under the deformation temperature range of 890-995 ℃ and strain rate range of 0.01-10 s^-1. According to the flow stress data obtained by compression tests, the deformation activations are calculated based on kinetics analysis of high temperature deformation, which are then used for deformation mechanism analysis combined with microstructure investigation. The results show that deformation mechanisms vary with deformation conditions： at low strain rate range, the deformation mechanism is mainly dislocation slip; at low temperature and high strain rate range, twinning is the main mechanism; at high temperature and high strain rate range, the deformation is mainly controlled by diffusion offl phase.

A Contraction-expansion Helical Mixer in the Laminar Regime

A contraction-expansion helical mixer which combines several features, viz. helical pipes for induction of secondary flows and sudden expansion and contraction array tor expansion vortices, has been designed to en- hance flow mixing. A fast competitive-consecutive diazo coupling reaction is used to test the mixing efficiency of contraction-expansion helical mixer. Furthermore, an image processing technique is applied for data visualization and monitoring the extent of mixing. The mixing performance is found to be superior in comparison to the regular helical mixer in the range of Reynolds number from 170 to 1540. Moreover, the mixing time of contraction-expansion helical mixer was found to be reduced by more than 25% compared to the regular helical pipe. Finally, a simple correlation is proposed for predicting the mixing time.

Effects of Tapered Diffuser Vane on the Flow Field and Noise of a Centrifugal Compressor

The effects of a three-dimensional tapered diffuser vane on the flow field and noise radiated from a centrifugal compressor are investigated by both CFD analyses and experiments. Tapered diffuser vanes are very useful not only for the reduction of the interaction tone noise but also for the improvement of the pressure recovery characteristics within the diffuser passage. By using tapered diffuser vanes, the interaction area between the impeller-discharge flow and diffuser vanes becomes small, and then the noise level of the discrete tone can be reduced remarkably as a result. Furthermore, by utilizing the visualization technique of vortical structures based on the CFD results, the scale of vortex shedding leaving from the leading edge of the diffuser vanes is found to be contracted and a tendency for the turbulence level to decrease is observed. This may be the cause of the attenuation of broadband noise components. The secondary flow, which is considered to be an obstruction of diffuser pressure recovery, can also be suppressed by the tapered diffuser vanes, and the pressure decrease observed in the throat part of the diffuser passage is further reducible.

Prediction of the Resonance Characteristics of Combustion Chambers on the Basis of Large-Eddy Simulation

In the last few years intensive experimental investigations were performed at the University of Karlsruhe to develop an analytical model for the Helmholtz resonator-type combustion system. In the present work the resonance characteristics of a Helmholtz resonator-type combustion chamber were investigated using large-eddy simulations (LES), to understand better the flow effects in the chamber and to localize the dissipation. In this paper the results of the LES are presented, which show good agreement with the experiments. The comparison of the LES study with the experiments sheds light on the significant role of the wall roughness in the exhaust gas pipe.

Performance analysis of a single-stage scroll compressor used in a drying heat pump over a wide condensing temperature range(30–80°C)

This study presents the performance of a new single-stage scroll compressor used for the heat pump drying of thermally sensitive materials over a wide temperature range. The performance of the new compressor was predicted by an ARI standard 540 map-based compressor model and verified by a semi-open drying heat pump system constructed for this purpose. A comparison of the experimental data with the predicted data proved that the new scroll compressor used in the drying heat pump works well, can supply a wide range of condensing temperatures （30--80℃） （without auxiliary heating）, and has a minimum coeffi- cient of performance （COP） above 2.0, even in the worst condition.

A New Simplified Model of Post Stall Transients inAxial Compression Systems

Based on the theory developed by Moors and Greitzer, a new simplifying approximation, which takesinto account the influence of higher harmonics of rotating waves, is proposed in this paper to get a simplified model of post stall transients in axial compression systems. This approximation leads to a set ofthree simultaneous nonlinear first order partial differential equations. The further investigation of poststall behavior for different response modes of instabilities (rotating stall and/or surge), recoverability,prestall period during stall inception, and the effect of compression system parameters on them canbe carried out by this model and has been discussed in detail in the present paper. It has been foundthat stall inception exhibits a large prestall period in the region with small slope of compressor characteristic, and in this region, final throttle setting, compressor characteristic and time-lag parametershave a strong influence on the period. The inertia parameters of blade rows have a strong influenceon the recoverability of compression systems and the blockage of stall cell at recovery point. Somequalitative comparisons with available experimental results and experience are made, and it shows thatthe proposed model is very simple and reliable.

A Quantum Secret Sharing Scheme Using Orbital Angular Momentum onto Multiple Spin States Based on Fibonacci Compression Encoding

Since the use of a quantum channel is very expensive for transmitting large messages, it is vital to develop an effective quantum compression encoding scheme that is easy to implement. Given that, with the single-photon spin-orbit entanglement, we propose a quantum secret sharing scheme using orbital angular momentum onto multiple spin states based on Fibonacci compression encoding. In our proposed scheme, we can represent the frequency of any secret message which is typically collection of bits encodings of text or integers as a bitstring using the base Fibonacci sequence, which is encoded multiple spin states for secret shares transmitted to participants. We demonstrate that Fibonacci compression encoding carries excellent properties that enable us to achieve more robust quantum secret sharing schemes with fewer number of photons.