Extracting Modes of Constrained Structure with Elastic Supports from Free Test Data

The dynamic flexibility (DF) and improved dynamic flexibility (IDF) methods can be applied to extract constrained structural modes from free-free modal test data. The residual flexibility method is also good for boundaries of constrained structure with rigid supports. Under elastic support boundary conditions both the DF and residual flexibility methods cannot produce accurate results. This paper expands the previously published IDF method to become a more general approach for structural design engineers. A new method called the general dynamic flexibility (GDF) method has been developed in this paper to extract constrained structural modes from free test data. The GDF method can always be applied as follows: (1) when the boundary support stiffness is very stiff, the GDF method can accurately obtain results from rigid support as by Liu et al. in 2001 and Zhang and Wei in 2003; (2) when the support stiffness is soft, the present method can produce results similar to those free-free modal parameters measured by hanging structures using rubber band; (3) when the support stiffness is zero, the method can reproduce true free-free modal parameters; and (4) when the support stiffness has any finite values, the GDF method can also achieve satisfactory results for engineering use. The algorithm included in the GDF method converges rapidly and is numerically stable in the analysis. This feature is very practical for many engineering applications for using the GDF method.     

Effect of supports on the redox performance of pyrite cinder in chemical looping combustion

Chemical looping combustion (CLC) is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO2 capture.The develop-ment of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process.As the solid by-product from the sulfuric acid production,pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process.The main components in pyrite cinder are Fe2O3,CaSO4,Al2O3 and SiO2 in which Fe2O3 is the active component to provide lattice oxygen.In order to sys-tematic investigate the functions of supports (CaSO4,Al2O3 and SiO2) in pyrite cinder,three oxygen car-riers (Fe2O3-CaSO4,Fe2O3-Al2O3 and Fe2O3-SiO2) were prepared and evaluated in this study.The results showed that Fe2O3-CaSO4 displayed high redox activity and cycling stability in the multiple redox cycles.However,both Fe2O3-Al2O3 and Fe2O3-SiO2 experienced serious deactivation during redox reactions.It indicated that the inert Fe-Si solid solution (Fe2SiO4) was formed in the spent Fe2O3-SiO2 sample,which decreased the oxygen carrying capacity of this sample.The XPS results showed that the oxygen species on the surface of Fe2O3-CaSO4 could be fully recovered after the 20 redox cycles.It can be concluded that CaSO4 is the key to the high redox activity and cycling stability of pyrite cinder.     

Wave Propagation and Mode Localization in Simply Supported Multispan Beams with Couplers on Supports

The influences of couplers on wave propagation and mode localization in simply supported multispan beams with couplers consisting of lumped rotational stiffness and mass on supports are studied. A transfer matrix equation governing the vibrational wave propagation in the simply supported multispan beams with couplers is newly derived and simplified. The eigenvalue of the simplified transfer matrix shows that the larger stiffness or the larger mass of the coupler makes the internal coupling between spans weaker and so it makes the system more sensitive to mode localization. As the wave frequency or the eigenvalues of the system increases, the mass effect is increased while the stiffness effect is decreased. In a case considering the large stiffness and mass at the same time, there is a region with relatively wider passbands and narrower stop bands having small attenuation rates and the normal modes in it become delocalized ones. As an example structure, a simply supported two span beam with a coupler at the midspan is considered.     

复合支护技术在软岩段巷道中的应用

本文针对花园煤矿开拓巷道中遇到的软岩具有松散破碎、高饱和吸水性、强膨胀性及流变性等的特点,分析研究了巷道支护失效的原因,在现场施工中采用了多种复合支护方式,保证了工程支护质量和施工安全,特别是在轨道大巷应用施工中取得了良好的支护效果。     

Numerical Analysis of a Tunnel Support Design in Conjunction with Empirical Methods

In this paper, preliminary support design of a tunnel was analyzed by numerical and empirical approaches. The case study for this analysis is a tunnel to be constructed on the Bilecik-Istanbul roadway in Turkey. The rock mass properties of the tunnel route and design support recommendations were obtained by using an empirical approach. The rock mass properties obtained from the empirical method were used as input parameters for the numerical analysis. The empirical and numerical results, in terms of support design, were evaluated. It was seen that the numerical analysis results supported by empirical values were logical and reliable.     

Analysis of Rim Supports for Off‐Axis Inflatable Reflectors. I: Loads

A structural analysis is performed for the rim support of a pressurized off‐axis paraboloidal membrane, serving as a space‐based solar concentrator. The function of the rim support is to take up the tensile forces created by the stretched membrane. This paper deals with the load analysis. The tensile forces transmitted by the membrane to the rim support are calculated, and are proportional to pb, where p is the inflation pressure and b is one‐half the major axis of the elliptical rim. Next, the internal forces and moments generated in the rim support by the membrane forces are calculated. The compression forces are considerably larger, at any point, than the shear forces; both are proportional to pb2. The bending moments are proportional to pb3. The critical point is found to be at the top of the rim, where both the bending moment and compression force are at their maximum.     

MOSSBAUER STUDY ON REDUCIBILITY OF SUPPORTED Eu_2O_3

ＭＯＳＳＢＡＵＥＲＳＴＵＤＹＯＮＲＥＤＵＣＩＢＩＬＩＴＹＯＦＳＵＰＰＯＲＴＥＤＥｕ_２Ｏ_３ＷｕＸｉａｏｈｕａ，ＨｓｉａＹｕａｎｆｕ，Ｈ．Ｍ．Ｗｉｄａｔａｌｌａｈ~１（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓ，ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｎａｎｊ?..     

Investigation of effects of viscoelastic boundary supports on transient sound radiated from a rectangular plate by modal strain energy method

This work considers analysis of transient sound radiation from an impact-excited rectangular plate with viscoelastic boundary supports based on the Modal Strain Energy (MSE) method. Vibration of the plate is approximated by double infinite series in the spatial coordinates. Each term of the series is constructed with vibration modes of beams having the same boundary conditions as the considered plate, multiplied by a time dependent function. Modal loss factor of each mode is obtained by the MSE method. The sound pressure for impact excitations is obtained in the time and frequency domain by numerical integration of the Rayleigh integral. Then effects of width of the viscoclastic boundary supports on the vibration response and the radiated sound pressure are investigated. It is shown that there is an optimum width of the support.     

关联规则在股票预测中的应用研究

使用经典Apriori算法,对股票数据进行一维和二维规则的挖掘。针对股票交易的特殊性,提出了使用换手率代替成交量作为数据预处理的对象,引入了平均支持度作为最小支持度进行股票数据的挖掘。实例验证证实了挖掘结果的正确性、有效性。     

齿间摩擦对机床渐开线齿轮支座振动之影响

由于不计齿间摩擦,机床机械传动领域内一直近似认为,只要主动轮输入扭矩保持恒定,渐开线齿轮支座就不会产生振动。研究表明,由于齿间存在摩擦,齿轮支座反力属性生财藏一变化,为此,机床渐开线层座会产生一定程度的强迫振动。文章指出,降低齿间摩擦系数并适当减小啮哈 角是减缓甚至避免机床齿轮支座振动的有效措施。