泌阳北部斜坡地区复杂断块群成像技术探讨

泌阳凹陷北部斜坡是河南油田的重点勘探区块之一,其构造产状复杂,断层发育；根据高精度勘探思路,提出多域数据重构体去噪方法进行规则干扰压制,层析反演静校正解决该区复杂地表条件引起的静校正方面的问题；然后基于各向异性双谱速度分析技术,进一步提高该区成像速度模型的精度；通过分析偏移孔径、去假频参数等处理参数对成像效果的影响,确...     

AUTO-SMASH: A self-calibrating technique for SMASH imaging

Recently a new fast magnetic resonance imaging strategy, SMASH, has been described, which is based on partially parallel imaging with radiofrequency coil arrays. In this paper, an internal sensitivity calibration technique for the SMASH imaging method using self-calibration signals is described. Coil sensitivity information required for SMASH imaging is obtained during the actual scan using correlations between undersampled SMASH signal data and additionally sampled calibration signals with appropriate offsets ink-space. The advantages of this sensitivity reference method are that no extra coil array sensitivity maps have to be acquired and that it provides coil sensitivity information in areas of highly non-uniform spin-density. This auto-calibrating approach can be easily implemented with only a small sacrifice of the overall time savings afforded by SMASH imaging. The results obtained from phantom imaging experiments and from cardiac studies in nine volunteers indicate that the self-calibrating approach is an effective method to increase the potential and the flexibility of rapid imaging with SMASH.     

Influence of digital audio filters on image reconstruction in MRI

This paper deals with the influence of the transient response and group delay of digital filters on the MRI signal and its aspects in image reconstruction. The consequence of digital filtration on the acquired signal will be shown in the time domain (κ-space) for three basic imaging methods-echo scan, radial scan and spiral scan. The influence of the group delay and transient response of filters will be explained and a method will be proposed which compensates both these phenomena while retaining all the advantages of digital filtration. The proposed method is based on applying the principle of signal superposition and on using the consequences of the sampling principle. The method works in the time domain. It is very simple and rapid and does not depend on the properties of the acquired signal or reconstruction algorithm. It will be shown and explained in which cases the transient response can be neglected and in which it has to be compensated. In the end, the results of the proposed methods will be shown for mentioned cases on a simulated signal in the image domain. © 1998 Elsevier Science B.V. All rights reserved.     

12CM15型连续采煤机截割齿轮箱内部结构缺陷及改造

在连续采煤机大修过程中,发现截割齿轮箱内部齿轮磨损严重,不能重复使用,经过分析发现,截割齿轮箱内部的齿轮轴及固定部分存在设计缺陷,使内部齿轮磨损严重,故对12CM15型连采机截割齿轮箱内部结构缺陷进行分析并提出改造方案。     

A novel approach to piecewise analytic agricultural machinery path reconstruction

Before analysing machinery operation in fields, it has to be coped with the problem that the GPS signals of GPS receivers located on the machines contain measurement noise, are time-discrete, and the underlying physical system describing the positions, axial and absolute velocities, angular rates and angular orientation of the operating machines during the whole working time are unknown. This research work presents a new three-dimensional mathematical approach using kinematic relations based on control variables as Euler angular velocities and angles and a discrete target control problem, such that the state control function is given by the sum of squared residuals involving the state and control variables to get such a physical system, which yields a noise-free and piecewise analytic representation of the positions, velocities, angular rates and angular orientation. It can be used for a further detailed study and analysis of the problem of why agricultural vehicles operate in practice as they do.     

某高校筒子楼的鉴定与改造加固

筒子楼是全国高校旧房改造中的重点工程。通过对上海某高校一筒子楼的质量检测、鉴定 ,简要介绍了此类工程的特点 ,以及合理有效的加固方法。经过对原建筑墙体、楼板、梁、节点的加固处理有效地提高了原工程的抗震性能和整体稳定性 ,对同类工程的加固有一定的借鉴作用。     

A RECONSTRUCTION OF THE KEY TO BEALE CIPHER NUMBER TWO

A reconstruction of the key used to encrypt B2 (Beale Cipher Number 2) reveals greater statistical anomalies in Bl than previously reported by Gillogly [8]. The 1885 pamphlet versions of the ciphers are used in this analysis. Several explanations of these anomalies are discussed. The application of artificial intelligence techniques to automated cryptanalysis of the Beale Ciphers is discussed.     

谈如何营造良好的商业街氛围

从大连西安路商业街的规划建设和实际使用状态出发,分析了目前该商业街存在的问题,主要从规划的角度,提出了营造良好商业氛围的方法,包括功能定位准确,空间界面人性化处理等,以指导商业街建设规划。     

Inverse problems involving the one-way wave equation: medium function reconstruction

Inverse problems are considered for the linear one-way one-dimensional wave equation or transport equation. In particular the wave speed reconstruction problem for a medium is discussed. Inverse problems for non-stationary, but also non-dispersive, media are examined; this means problems for which the slab medium parameters are both spatially and temporally varying are considered. Both theoretical and numerical results are given for the methods presented. Theoretical results obtained for this equation can be generalised to second order equations.     

减少锅炉沉渣池排污量的实践

通过分析珠江电厂排渣系统的运行现状，指出渣池排污量大的原因是渣斗溢水量大造成的，为此，提出一系列具体的解决措施，在实际应用中收到了良好的效果。