勇于创新 独辟徯径——试论郭沫若早期的甲骨文字研究

卓越的无产阶级文化战士郭沫若同志,在哲学社会科学领域里具有多项学科的成就。他不仅在文学,而且在史学、古文字学、考古学上都功绩卓著。他是我国第一位马克思主义史学家,也是富有创见、硕果累累的古文字学家。关于他在古文字学上的成就,近年来有少数文章作过评述。作为一个学术课题,还应深入探索他的治学方法,总结他的治学经验,进一步推动我们今天这个领域的研究工作。本文专就他早期研治甲骨文字的指导思想和科学方法,作一初步的阐述,抛砖引玉,就正于专门家。

古文旧注辨正六则

要读懂古书,的确是很难的.鲁迅主张“须仗我们自己的知识,给它注解,补足.待到翻成精密的白话之后,这才算是懂得了.“(《此生或彼生》)听起来容易,做起来难.四十六年前闻一多先生在他的《楚辞校补·引言》中说:

Research in non-equalization machining method for spatial cam

Many kinds of devices with cam have been widely used in various mechanical equipments. However, non-equalization machining for spatial cam trough remains to be a difficult problem. This paper focuses on the analysis of running conditions and machining processes of spatial cam with oscillating follower. We point out the common errors in the biased distance cutting. By analyzing the motion of oscillating follower of spatial cam, we present a new 3D curve expansion model of spatial cam trough-outline. Based on this model, we have proposed a machining method for trochoidal milling with non-equalization diameter cutter. This new method has led to a creative and effective way for non-equalization diameter machining for spatial cam with oscillating follower.

Tool-path planning for free-form surface high-speed high-resolution machining using torus cutter

In CNC machining, two essential components decide the accuracy and machining time for a sculptured surface: one is the step-size interval, the other is the tool-path interval. Due to the limitation of the conventional method for calculating the tool-path interval, it cannot satisfy the machining requirement for high-speed and high-resolution machining. Accordingly, for high-speed and high-resolution machining, the current study proposes a new tool-path interval algorithm, plus a variable step-size algorithm for NURBS. Furthermore, a new type cutter, which can improve the cutting efficiency, is investigated in the paper. The transversal equation of the torus cutter onto the flat plan is given in this paper. The tool-path interval is calculated with the transversal equation and the proposed algorithm. The illustrated example shows that the redundant tool paths can be reduced because an accurate tool-path interval could be calculated.

Tool selection and collision-free in 5-axis numerical control machining of free-form surfaces

The methodology of 5-axis cutter selection to avert collision for free-form surface machining by flat-end cutters is presented. The combination of different cutters is adopt aiming at short machining time and high precision. The optimal small cutter is determined based on the geometric information of the points where a cutter most probably collide with the machined surface. Several larger cutters are selected to machine the surface in order to find the interference-free area. The difference of machining time for this area between the optimal small cutter and the large cutters is calculated. The functional relationship between the machining time and the radius of a cutter is established, by which the optimal number of cutters is obtained. The combination of cutters, which possesses the minimum overall machining time, is selected as the optimal cutter sizes. A case study has demonstrated the validity of the proposed methodology and algorithms.

Mycotoxins Incidence in Romanian Malting Barley （Harvest 2009）

The presence of deoxynivalenol （DON）, total aflatoxins, ochratoxin （OTA） and zearalenone （ZEA） was investigated in malting barley samples harvested in Romania using an ELISA method （VERATOX, Neogen）. In 7 out of 14 barley samples the aflatoxins were not found at detectable levels （50%）. In 9 out of 14 barley samples the OTA was not found at detectable levels （64.29%）. In 1 out of 14 barley samples the DON was not found at detectable levels （7.14%）. In 13 out of 14 barley samples （92.86%） the ZEA was above the acceptable limit （100μg/kg）. For all barley samples the aflatoxins, DON and OTA were in line with European Union regulations in force （4.0 μg/kg for aflatoxins, 1,250.0μg/kg for DON, 5.0 μg/kg for OTA, respectively）.

Experimental study of the effect of blade tip clearance and blade angle error on the performance of mixed-flow pump

The hydraulic performance test of the mixed-flow pump has been carried out through selecting different blade tip clearances and various blade angle errors.The ratio of the mixed-flow pump efficiency reduction and the blade tip clearance variation(η/δ) varies with the flow rate coefficient revealing a parabolic trend.An empirical equation has been developed for the mixed-flow pump model by parabolic fitting.For the same blade tip clearance variation δ,the mixed-flow pump efficiency reduction η increases rapidly as the flow rate rises.For any given flow rate,the efficiency,the head and the shaft power of the mixed-flow pump all decrease with the increase of the blade tip clearance.Among them,the efficiency reduction η varies approximately linearly with the blade tip clearance variation δ.When the angle of an individual blade of the mixed-flow pump has a deviation,the performance curves will move and change.These curves have consistent change directions with the performance curves under the condition of all the blades rotated at the same time,but have smaller offset and lower range of variation.When an individual blade angle error changes to ±2°,the optimal efficiency of the mixed-flow pump will have no significant difference.When the individual blade angle error increases to ±4°,the optimal efficiency will decrease by 1%.

GENERATION METHOD FOR FIVE-AXIS NC SPIRAL TOOL PATH BASED ON PARAMETRIC SURFACE MAPPING

A new spiral tool path generation algorithm for 5-axis high speed machining is proposed in this paper.Firstly,the voltage contours are calculated to satisfy the machining parameters in the mapping parametric domain by means of the electrostatic field model of partial differential equations.Secondly,the mapping rules are constructed and the machining trajectory is planned out in the standard parametric domain in order to map and generate the spiral trajectory in the corresponding parametric domain.Finally,this trajectory is mapped onto the parametric surface for the obtainment of the spiral tool path.This spiral tool path can realize the machining of complicated parametric surface and trimmed surface without tool retractions.The above-mentioned algorithm has been implemented in several simulations and validated successfully through the actual machining of a complicated cavity.The results indicate that this method is superior to the existing machining methods to realize the high speed machining of the complicate-shaped cavity based on parametric surface and trimmed surface.

TOOL ORIENTATION PLANNING FOR FIVE-AXIS CNC MACHINING OF OPEN FREE-FORM SURFACES

For the geometry characteristics of open free-form surfaces,it is hard to consider global interference during the planning of feasible domains.Therefore,the optimal kinematic orientation of tool axis will no longer be confined to the boundary of feasible domains.In this paper,according to the principle demanding that the tool should be fitted to a surface as close as possible and relevant processing parameters,a feasible domain of tool orientation for each cutter contact is planned in the local feed coordinates system.Then,these feasible domains of the tool orientation are transformed into the same coordinates system of the machine tool by the inverse kinematics transformation.The linear equations based feasible domain method and Rosen gradient projection algorithm are used to improve the optimization process in precision and efficiency of the algorithm.It constructs the variation of tool orientation optimization model and ensures the smoothness of tool orientation globally.Simulation and analysis of examples show that the proposed method has good kinematics performance and greatly improves the efficiency.