Convergence Behavior of NLMS Algorithm for Gaussian Inputs: Solutions Using Generalized Abelian Integral Functions and Step Size Selection

This paper studies the mean and mean square convergence behaviors of the normalized least mean square (NLMS) algorithm with Gaussian inputs and additive white Gaussian noise. Using the Price’s theorem and the framework proposed by Bershad in IEEE Transactions on Acoustics, Speech, and Signal Processing (1986, 1987), new expressions for the excess mean square error, stability bound and decoupled difference equations describing the mean and mean square convergence behaviors of the NLMS algorithm using the generalized Abelian integral functions are derived. These new expressions which closely resemble those of the LMS algorithm allow us to interpret the convergence performance of the NLMS algorithm in Gaussian environment. The theoretical analysis is in good agreement with the computer simulation results and it also gives new insight into step size selection.     

Effects of ion irradiation on Zr52.5Cu17.9Ni14.6Al10Ti5 (BAM-11) bulk metallic glass

Bulk metallic glasses are intriguing candidates for nuclear applications due to their inherent amorphous structure, but their radiation response is largely unknown due to the relatively recent nature of innovations in bulk metallic glass fabrication. Here, microstructural and mechanical property evaluations have been performed on a Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ bulk metallic glass (BAM-11) irradiated with 3 MeV Ni⁺ ions to 0.1 and 1.0 dpa at room temperature and 200 °C. Nanoindentation hardness and Young's modulus both decreased by 6–20% in samples irradiated at room temperature, with the sample irradiated to 1.0 dpa experiencing the greatest change in mechanical properties. However, no significant changes in properties were observed in the samples irradiated at 200 °C, and transmission electron microscopy showed no visible evidence of radiation damage or crystallization following ion irradiation at any of the tested conditions. These results suggest that BAM-11 bulk metallic glass may be useful for certain applications in nuclear environments.     

基于数字孪生的高动态生产系统联动决策方法

个性化需求引发的随机高动态干扰加大了生产系统高效运作的难度。如何面向随机高动态干扰,构建在线联动决策方法,实现对生产系统的精准决策以支持各生产单元的高效协同成为关键挑战。以模块化生产的多单元联动运作为研究对象,基于数字孪生构建多单元联动决策架构、机制和模型。通过实时精准映像与动态虚拟仿真,实现高动态生产系统的在线协同运作和自主联动决策。最后以某大型化工企业的多单元联动运作为例,验证所提方法可以显著降低系统运作总成本,实现复杂多单元生产系统在高动态干扰下的最优化运作。     

混合动力车用阀控式铅酸蓄电池负极碳添加剂的研究进展

介绍了混合动力车用阀控式铅酸蓄电池负极加碳的最新研发进展。加入较高含量碳材料对铅酸蓄电池性能有所改善,如增加导电性,使硫酸铅分布均匀,增加比表面积,降低极化,增大电容作用等,也指出了加入碳后一些不利的影响。     

绿色电镀技术系统示范项目

根据生产实践和现场数据,详细介绍了安美特公司配合中国环境保护产业协会和中国表面工程协会共同启动的绿色电镀技术示范项目的实施状况。该示范项目的核心内容是包括前处理、锌合金电镀及后处理在内的防腐蚀镀层组合实用技术。经被试点电镀企业投放于大生产实践的长期使用,该示范项目取得了上佳的环境和经济效益:单位水耗降低了85%,单位能耗降低了65%;电镀废水中COD减少了50%,电镀速率提高了50%,产品一次合格率从90%提高到98%;钝化液中锌杂质削减了65%～95%,铁杂质削减了85%～95%,而且彻底杜绝了锌镍合金电镀过程中氰化物的产生。     

短时序列预测的新方法

We propose a procedure to forecast short time series with stable seasonal pattern. This new method is motivated by the observations that short time series arise in many situations for the fierce competition. The quantity to be predicted is a yearly accumulation assuming that the partially accumulated data within the year are available. A simple model is proposed to describe the relationship between the yearly accumulation and partial accumulation and analytic results are obtained for both the point prediction and the predicative distribution. A comparison will be conducted between this model and traditional time series forecasting model with data from telecommunication industry. This method works better than the traditional models when only small amount of data are available. It can also be applied to forecast individual observations with a proper disaggregation algorithm.     

细水雾系统在建筑灭火应用中的理论研究

为了预测细水雾系统在连续运行和间歇运行方式下有障碍火焰熄灭情况,基于受限空间内的气体成分的质量守恒和空间的能量守恒,建立了一个预测受限空间内细水雾系统灭火效果的瞬态模型．该模型对于受限空间温度、干态氧气体积分数能进行较好的预测研究;在同样的火焰情况下,采用间歇运行方式能提高灭火效果而且减小耗水量．     

The Cost of Cache-Oblivious Searching

This paper gives tight bounds on the cost of cache-oblivious searching. The paper shows that no cache-oblivious search structure can guarantee a search performance of fewer than lg elog  _B N memory transfers between any two levels of the memory hierarchy. This lower bound holds even if all of the block sizes are limited to be powers of 2. The paper gives modified versions of the van Emde Boas layout, where the expected number of memory transfers between any two levels of the memory hierarchy is arbitrarily close to [lg e+O(lg lg B/lg B)]log  _B N+O(1). This factor approaches lg e≈1.443 as B increases. The expectation is taken over the random placement in memory of the first element of the structure.     

Design of Cellular Composite Sandwich Panels for Maximum Blast Resistance Via Energy Absorption

This paper presents a design methodology for optimizing the energy absorption under blast loads of cellular composite sandwich panels. A combination of dynamic finite element analysis (FEA) and simplified analytical modeling techniques are used. The analytical modeling calculates both the loading effects and structural response resulting from user-input charge sizes and standoff distances and offers the advantage of expediting iterative design processes. The FEA and the analytical model results are compared and contrasted then used to compare the energy response of various cellular composite sandwich panels under blast loads, where various core shapes and dimensions are the focus. As a result, it is concluded that the optimum shape consists of vertically-oriented webs while the optimum dimensions can be generally described as those which cause the most inelasticity without failure of the webs. These dimensions are also specifically quantified for select situations. This guidance is employed, along with the analytical method developed by the authors and considerations of the influences of material properties, to suggest a general design procedure that is a simple yet sufficiently accurate method for design. The suggested design approach is also demonstrated through a design example.