基于FPGA乘法器架构的RNS与有符号二进制量转换

RNS(余数数制系统)是一种整数运算系统,在粒度精确性,能源损耗和响应速度上有很大的优势.从RNS到二进制数的输入输出转换是基于余数算法的专用架构实现的关键.本文提出了一个基于N类模的RNS与有符号二进制量的通用转换算法在FPGAs的乘法器上的实现过程.该算法能更有效地进行有符号数与RNS的转换.基于该算法类型乘法器在同类型乘法器中显示出了速度优势.文章中该架构被映射到Altera的10K系列的FPGA上.     

38—THE EFFECT OF SPINNING CONDITIONS ON THE TENSILE PROPERTIES OF CORE-SPUN YARNS

A critical assessment of the merits of core-spinning by means of comparisons of the strength and extension of core-spun yarns with all-staple-fibre yarns forms the basis of this paper. Core-spinning was done by introducing the filament under tension into the drafted strand as the latter entered the front rollers of the ring-frame. A 20-den (2.2-tex) nylon monofilament was used as core, and three types of staple-fibre covering were investigated. The effects of twist, pre-tension, and feeding arrangements on the geometrical disposition and tensile properties of the yarns were examined. Improvements in strength are, in general, realized at low twists by the incorporation of the filament and by further constraining it to occupy the core. The contribution of the components to the yarn strength and the process of breaking were also subjected to a detailed study. The studies reported provide an interesting insight into the extent of cohesion developed between the fibres during the straining of the yarn and its influence on the process of breaking and ultimately on yarn extension.     

10—THE MECHANICS OF FRICTION-TWISTING

An analysis is given from which equations can be derived that relate the variations of twist factor, tension, and yam path through a false-twist friction spindle. The solution of these (differential) equations leads to predictions about the dependence of over-all twist factor and tension ratio on, among other parameters, the ratio of yam speed to spindle speed, the angle of wrap, and the input tension. These are compared with the early experimental results of Arthur and Weller and with more recent results.

The equations also yield the variation of twist factor and tension over the spindle surface and could be used to estimate wear.

The early part of the analysis would have general application in any situation in which a yarn is moving over a surface.     

43—FIBRE MIGRATION IN OPEN-END-SPUN YARNS

A study of the migration of fibres in open-end-spun yarns is reported. Samples of viscose rayon yarns were produced by the drum and air-vortex methods, and the results obtained on them were compared with those for a ring-spun yarn made from the same fibre. Migration was studied by determining three parameters: the helix profile, the mean fibre position, and the r.m.s. deviation, i.e., the root-mean-square value of the radial deviation of the helix profile from the mean fibre position. The geometry of fibre-packing in the yarn cross-section and the fibre extent were also studied.

It is shown that open-end-spun yarns are somewhat different in character from ring-spun yarns and that the most basic structural differences are found in the fibre extent, fibre migration, and fibre-packing density. The fibre migration in an open-end-spun yarn is shown to be as little as one-sixth of that in a typical ring-spun yam, and the difference in structure is important in that it can affect the yarn properties. It is concluded that the observed low strength of most open-end-spun yarns can be attributed to the poor fibre extent and inferior fibre migration within the yarn body and that their relatively high elongation can be explained in terms of the folded and entangled nature of the fibres.

An examination of the fibre geometry in the yarn shows that the design features of drum spinners are important with regard to the determination of the fibre extent, a tangential feed being preferable to an axial one.

The yarn cross-sections demonstrate that open-end spun yarns generally have a lower fibre-packing density than ring-spun yarns, which tends to give the yarn a more bulky nature; this is consistent with what might be expected from an assembly of tangled fibres.     

32—SELF-TWIST YARN

A new type of yarn structure, which has been named self-twist yarn, is described. It is a two-ply structure in which both the strand and plying twists alternate S and Z along the yarn. The strength properties of the yarn and their dependence on the various yam parameters are given for 60/64s wool fibres, and it is shown that the strength can approach that of conventional yarns.