Analysis of the ∈-Expansion in Turbulence Theory: Approximate Renormalization Group for Diffusion of a Passive Scalar in a Random Velocity Field

The validity of the k803322t82/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0">-expansion in the turbulence problem is discussed using the example of diffusion of a passive scalar in a random velocity field. A generalization of Wilson's rule for calculating a diagram of arbitrary order is introduced. The resulting perturbation series, while having zero radius of convergence, is summed exactly yielding amplitudes which differ from those obtained to lowest order in the k803322t82/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0">-expansion by only a few percent. The properties of the expansion are analyzed in detail and it is shown that various subsets of diagrams, while differing by an infinite number of terms, give close results in the vicinity of the fixed point. This indicates nontrivial compensation of high-order interactions in turbulence. The irrelevance of high-order couplings is demonstrated for arbitrary values of k803322t82/xxlarge8712.gif" alt="isin" align="MIDDLE" BORDER="0">. The quality the approximation is tested by comparison with numerical experiments on diffusion of a passive scalar in a band-limited random velocity field in the limit of infinite Peclet number.     

Theoretical consistency test of steam transport properties

The kinetic theory of polyatomic gases is used to test the mutual consistency of the thermal conductivity, viscosity and specific heat of low-pressure steam from 100° to 700°C. No inconsistency exists within the cited tolerances of the skeleton tables recommended by the Sixth International Conference on the Properties of Steam, but there is some basis for suspecting that the high-temperature thermal conductivity values are slightly low. Methods for tightening the consistency bounds are suggested.     

Heat Inputs to Sub-mK Temperature Cryostats and Experiments from γ-Radiation and Cosmic Ray Muons

We measured the spectrum of energies deposited by k32261t7v1835080/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-radiation, emanating from radioactive materials in the laboratory that houses our mK cryostat, and by cosmic ray muons. This allows us to quantify the heat input that adversely affects the lowest temperature accessible in sub-mK experiments. We use our nuclear stage, stage plate and experimental cell as a prototype k32261t7v1835080/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">modelk32261t7v1835080/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> system, and calculate the power deposited due to low energy (below 2.65 MeV) background radiation k32261t7v1835080/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0"> quanta (~20 pW). This is significantly less than the power (~120 pW) deposited in the nuclear and experimental stages by muons. Installation of a 5 cm thick lead wall around the cryostat reduced the energy due to the flux of k32261t7v1835080/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0"> quanta by a factor of ~10 to ~2 pW, and the number of k32261t7v1835080/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0"> quanta by a factor of ~20. The lower energy, k32261t7v1835080/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">softk32261t7v1835080/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> cosmic ray component was also affected by introducing the same thickness of lead, reducing the overall count of cosmic ray derived particles by ~15% and the heat leak to ~100 pW.     

Pietra Serena Mining in Fiesole. Part II: Geological Situation

The results are presented for the investigations into the geological estimate of Macigno formation representing an Oligocene-Miocene turbiditic sequence of the Northern Apennines, from the coarse-graded beds of which the k4x24/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">Pietra Serenak4x24/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> quarry stone was mined. It is shown that the sedimentological features, the physico-mechanical properties, and the mineralogical composition of rocks govern the distinctions in the operating performances.     

Experience with Construction of Underground Sections of Buildings by the “From Top Down” Scheme

Experience gained with the method of installing the underground section of a building k136ukt637n/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">from the top downk136ukt637n/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> is described in an example of the construction of specific projects in Moscow, design, construction and monitoring problems are exposed, advantages and disadvantages of this method are indicated, and observational data are cited for the settlements of existing buildings located within the zone of influence of new construction.     

亚45 nm技术节点平面式硅基CMOS电路制作的材料选择

随着45nm技术的临近，减小单个晶体管尺寸以提高晶体管集成度的方法逐渐达到物理极限。传统掺杂多晶硅，二氧化硅栅结构因硼杂质扩散穿透、多晶硅耗尽和电子隧穿等效应使深亚微米器件的性能退化。此外，沟道载流子迁移率退化也阻碍Si基MOS性能的提升。因此，需采用高k介质、金属栅和应变硅等新材料、新技术以改善Si基MOS管性能。本文在介绍这3种新材料优势的同时，分析了适合未来平面式硅基CMOS技术中的高介电常数材料和金属栅材料的种类，指出了未来电路中新材料的进一步发展方向。     

改进型booth华莱士树的低功耗、高速并行乘法器的设计

采用一种改进的基4 BOOTH编码和华莱士树的方案,设计了应用于数字音频广播(DAB)SOC中的FFT单元的24×24位符号定点并行乘法器.通过对部分积的符号扩展、(k:2)压缩器、连线方式和最终加法器分割算法的优化设计,可以在18.81 ns内完成一次乘法运算.使用FPGA进行验证,并采用chartered 0.35 μm COMS工艺进行标准单元实现,工作在50MHz,最大延时为18.81 ns,面积为14 329.74门,功耗为24.69 mW.在相同工艺条件下,将这种乘法器与其它方案进行比较,结果表明这种结构是有效的.     

基于网络Voronoi图的道路网络连续k近邻查询

道路网络中的连续查询是查找在一条路径上满足查询条件的对象。它是空间网络数据库中的一种重要查询类型。现提出了道路网络中基于k阶Voronoi图的连续k近邻查询方法，该查询方法用分枝限界的思想动态地创建局部Voronoi图，降低了查询代价。     

45nm工艺与关键技术

介绍了45 nm芯片所采用的关键工艺技术:193 nm ArF干法/浸没式光刻技术、低k电介质技术、高k电介质技术和应变硅技术等。英特尔45 nm全功能153 MB SRAM芯片与65 nm芯片相比,晶体管密度提高了2倍,晶体管开关速度提高20%以上,晶体管漏电流降低到65 nm芯片的1/5,存储单元面积为0.346μm2。指出英特尔45 nm芯片MPU将在2007年下半年实现量产,并且继英特尔之后,TI、IBM、特许、英飞凌、三星、台积电和台联电等均已推出了45 nm芯片,说明45 nm芯片技术正在日益走向成熟。     

平均空间占有量对混沌的度量——均匀度理论之应用

对于一条离散的、混沌的轨道,独占球体积是轨道上一个点的空间占有量,k步混沌强度（kSCM）是轨道的平均空间占有量,它被用于度量混沌轨道的特征.取k=400,应用400步混沌强度（400SCM）,对Lorenz系统和Henon map进行分析,400SCM与李亚普诺夫指数有相似的走势.Lorenz系统的Prandtl数a与400SCM的关系是单调的,Rayleigh数b在[12,28]的区间上是混沌的,没有准周期窗口,但参数c与400SCM的关系不是单调的,说明在c∈[2.666,4.566]区间上,准周期窗口与混沌窗口交错.对Henon map的计算结果表明b=1.7和a=1.3附近存在准周期窗口.基于上述计算结果得出k步混沌强度能够准确度量混沌特征.