掘进机隧道开挖的最新技术与未来发展

ＴＢＭ技术在隧道开挖中的应用已在施工行业取得了强有力的地位。现在必须抓住机会分析已取得的成绩和存在的不足 ,并研讨如何实现未来工程的目标。掘进机制造商每天都从各个工地得到信息反馈 ,这些实践经验对于ＴＢＭ技术的工艺细节和未来构思的有效改进是最重要的。显然 ,这些经验不可能用一篇文章讨论完 ,但应对有些至关重要的事实给予重点关注。这些事实或与目前的技术发展有关 ,或可被用来解决降低隧道工程现存的风险因素。本文谈及的ＴＢＭ隧道施工为开挖硬岩隧道 ,采用两种类型的硬岩掘进机———护盾式和非护盾式。1　最新技术与发…     

A parallel adaptation algorithm for recursive-least-squaresadaptive filters in nonstationary environments

An accurate new expression for the steady-state tracking performance of exponentially weighted recursive-least-squares (RLS) adaptive filters in a random walk scenario is derived. This relation is then used to provide a detailed comparison between RLS-performance and that of normalized least-mean-squares adaptive filters. Further, a variable-forgetting-factor algorithm referred to as the parallel adaptation algorithm that approximately achieves the theoretical minimum mean-squared-error performance in a random walk scenario is developed. Extensive simulation results are presented to support the present findings and demonstrate the improved performance of the proposed algorithm in a number of different applications     

Spatial Ability,Student Gender,and Academic Performance

Two groups of engineering students were tested for spatial ability (Mental Rotation Test = MRT). There were sex differences favouring males, similar to those seen in other academic programs. There were no significant sex differences in academic course performance, suggesting that differences in spatial ability as measured by the MRT do not have an impact on course performance. In addition, minimal experience with the mental rotation task produced large gains in performance and reduced the magnitude of sex differences. The results suggest that sweeping statements about the relation between differences in spatial ability and performance in science and mathematics subject areas, especially with reference to females, must be viewed with caution.     

The mathematical modeling of leaching systems

Leaching processes may be described by two kinds of models—a micromodel that deals with changes to solid particles while they undergo leaching and a macromodel that deals with system changes. This article presents the micromodel by writing a general mathematical equation for single particle leaching, integrating this equation over all initial particle sizes and integrating over the residence time distribution applicable to the leaching system. The macromodel deals with material and heat balances and utilizes surface area integrals arising from the micromodel. The result is an overall model that describes both batch and continuous leaching in stirred tanks, and which may be expanded to include heap and dump leaching.     

Test-retest stability of the Wechsler Adult Intelligence Scale—Revised in the assessment of head-injured patients.

Wechsler Adult Intelligence Scale—Revised protocols from 48 male and 12 female head-injured patients (mean age?=?27.02) with a mean test–retest interval of 8.48 months were analyzed to determine test–retest stability. Stability coefficients were .91, .84, and .92 for Verbal Intelligence Quotient (VIQ), Performance Intelligence Quotient (PIQ), and Full-Scale Intelligence Quotient (FSIQ), respectively. On retest, mean improvement was 4.08, 8.02, and 5.92 points for VIQ, PIQ, and FISC, respectively. Improvements were positively correlated with years of education and tended to correlate negatively with the number of months postinjury. Subscale stability coefficients ranged from .92 for Information to .61 for Digit Span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Iodo-substituted 4-aminoazobenzenes and 4-phenylazonaphthylamines-dyes for synthetic-polymer fibres

2-Iodo-4-nitroaniline, 2,6 diiodo-4-nitroaniline, 6-iodo-2,4-dinitroaniline and 2-cyano-6-iodo-4-nitroaniline were prepared from the appropriate nitroanilines by various iodination procedures. Diazotisation of these, and coupling to N-ß-cyanoethyil-N-ß-hydroxyethylaniline, 2-methoxy-5-acetylamino-N-ß-cyanoethyl-N-ß-hydroxyethylaniline and N-ß-hydroxyethyl-1-naphthylamine afforded a series of red to blue disperse dyes. The colour, dyeing and fastness properties of the dyes are evaluated with respect to analogous fluoro-, chloro-and bromo-substituted derivatives.     

Thermal and mechanical properties of block copolymers of poly(hexamethylene terephthalate) and poly(oxyethylene) units

Block copolyetheresters of poly(hexamethylene terephthalate) (6GT) with poly(oxyethylene) terephthalate (POET) units have been prepared by polycondensation and certain of their thermal, morphological and mechanical properties have been determined. The copolymers rich in 6GT or POET units show the crystalline characteristics of the single respective homopolymers, whereas in the middle of the composition range crystalline phases of both types coexist. Increase in the proportion of POET units causes a decrease in the melting and glass transition temperatures and in the crystallisation rates whilst concomitantly the mechanical properties change from fibrous to elastomer in type. The results are interpreted in terms of a polycrystallite model in which the compostion-dependent nature of the crystallites and tie bars determines the overall mechanical properties of the copolymers.     

Analysis of finite parallel-plate waveguide arrays

The radiation and phase scanning properties of a planar array are investigated using wedge diffraction theory. The TEM and TE01radiation patterns are determined assuming that each guide is excited with equal amplitude but variable phase which is specified by the desired scan angle. Since the TE01pattern can be used directly as theH-plane radiation pattern of an equivalent rectangular waveguide array, the analysis for this instance is extended to consideration of aperture reflection coefficients     

Performance of subgroups of left-handers and right-handers.

Examined whether observed differences between subgroups of left-handers (LHs) were restricted to the occasional motor task and whether segregation between consistent LHs (CLHs) and inconsistent LHs (ILHs) based on performance patterns would be possible. 118 CLHs and ILHs and 57 right-handed (RHs) undergraduates completed hand and foot preference questionnaires and a battery of performance tests (e.g., tapping). With few exceptions (e.g., strength), CLHs and ILHs showed similar performance. Neither CLHs nor ILHs appeared to suffer from inferior nonpreferred hand performance relative to the other group. Overall, LHs performed at least as well as RHs and better in some instances. (French abstract) (PsycINFO Database Record (c) 2011 APA, all rights reserved)