Furthermore , the internal forces and displacements when pretensioning the structure can be obtained easily by means of the suggested method under many conditions such as pretensioning a tendon , pretensioning several tendons simulta ? neously , pretensioning one strand in a tendon or pretensioning tendors by stages and in groups 当单根杆件施加预应力、多根杆件施加预应力、同一杆件各股分别施加预应力以及分级分批施加预应力时，采用本文提出的方法可方便求得各工况下预加应力全过程的网架内力和变位及其变化规律，并可一次性地完成预应力施加工作。
In this paper , the research progress of ac losses of high temperature superconductors and the existing problems on ac losses investigation are introduced ; the characteristics of the critical current and ac losses of hts tapes , stacked tapes and hts coil , such as electro - magnetic characteristics , the anisotropy , the mechanics characteristics and the effects of insular layer between stacked tapes and the influence of frequency of ac transport current etc , are investigated 本文在系统介绍高温超导体的交流损耗及其研究现状与存在问题的基础上，从理论和实验两方面，研究了bi系高温超导单根带材、多根超导并联组合带材、及超导线圈的临界电流与交流损耗的特性：重点研究了交流损耗与临界电流的电磁特性、机械特性、各向异性特性、及带间绝缘层与传输电流频率对交流损耗的影响等。
To study the of effect of insulator layer among tapes in a stack and the influence of frequency of ac transport currents on ac losses , ac losses of a single tape and stacks were measured for ac transport current with different frequencies in two cases : with and without insulator among the tapes in a stack . theoretical formulae to calculate hysteresis losses in stacked tapes were also presented 研究了高温超导带材及并联堆叠带材的交流损耗随传输电流频率的变化情况；及多根并联组合超导带间绝缘对交流损耗的影响情况；实验研究了并联堆叠带材的各向异性特性；给出了有限根超导带并联时，磁滞损耗的理论计算公式。
However , in practical systems , the deployment of antenna array is difficult due to the size and / or price limitation . recently a new form of space diversity , which is based on relay channel model and through users ’ help for each other , named cooperative diversity has become an atructive technology 但是由于尺寸,能量,价格等因素限制,在移动终端使用多根天线具有一定的困难,最近一种基于中继信道模型的,同时利用多个用户的互相协助而实现空间分集的技术? ?协同分集技术,成为一个新的研究热点。
And allow control of the fission rate inside the reactor , some fuel assemblies are fitted with control rods . each control rod assembly consists of a number of absorber rods attached to a spider assembly and coupled to the control rod drive mechanism . the absorber rods are made up of neutron absorbers such as silver , indium and cadmium 及控制反应堆的核裂变，部份燃料组件装配有控制棒，控制棒组件由星型架及多根含银ag铟in和镉cd的中子吸收体棒所组成，因此移动控制棒的上下位置就可以控制反应堆内中子的数目与及核裂变。
When we analyze the characteristic of several wire antennas attached to an arbitrary faceted conducting body we must divide it into two cases . one is that the conducting body is electrically small , the mutual coupling and infection between the antennas and conducting body are very obvious . so we must model them precisely and the shape of the conducting body , the length and location of the antennas etc . are must be tak en into account 金属多面体上有多根线天线分两种情况，一是金属多面体是电小尺寸，此时，天线和金属多面体都是属于精细结构，天线之间的互耦以及金属多面体对天线影响都非常明显，所以金属多面体的形状以及天线的长短、位置等对计算的结果影响非常大，因此必须精确建模，把所有的因素考虑在内。
Space - time coding technique is a coding technique which is applied in mimo system . it correlates to multiple antennae and signals transmitted in different periods in temporal and spatial domains , which enable the receiver can overcome fading over mimo channel and reduce error code transmitted 空时编码是一种用于mimo系统的编码技术,该编码在多根发射天线和各个时间周期的发射信号之间能够产生空域或时域的相关性,这种空时相关性可以使接收机克服mimo信道衰落和减少发射误码。
Characteristic analysis of single wire antenna attached to a conducting body or plate is done in many papers but very few people pay attention to the case of several wire antennas . a deep research for several wire antennas attached to an arbitrary faceted conducting body is made in this paper 许多专家、学者都对金属物体、金属平板上的单根线天线的特性进行了许多分析和研究，但是多根线天线的情况却研究得较少，本文对金属多面体上有多根线天线情况进行了深入的研究。
In order to study the main effected factors of the aseismic performance of concrete dampers , experiment of dampers in forms of concrete ductile columns was conducted subjected to low cyclic loading , the damage pattern , hysteresis behavior , ductility factor and equivalent viscous damper factor of the dampers were obtained 摘要为考察混凝土延性柱耗能器抗震性能的主要影响因素，通过对多根延性柱耗能器的低周反复荷载试验，得到其破坏形态、滞回特性、延性系数、等效黏滞阻尼系数等参数。
Recently , multiple input multiple output ( mimo ) system which originates from the employment of multiple antennas at transmitter and receiver has many advantages such as large system capacity , high spectral efficiency . on the other hand , orthogonal frequency division multiplexing ( ofdm ) which bases on the orthogonal transmission of sub - carriers also has some obvious merits such as strong anti - multipath ability , high spectral efficiency . the combination of the two techniques mimo - ofdm , has become a hotspot recently and regarded as promising technique for future next - generation mobile communication systems 近来,在无线通信系统中的收发两端同时使用多根天线的多入多出( mimo , multiple - input - multiple - output )通信结构,具有系统容量大、频谱效率高等优点;基于正交的多路子载波并行传输的正交频分复用( ofdm , orthogonalfrequencydivisionmultiplexing )技术,具有抗多径能力强、频谱效率高等优点,二者的结合,即mimo - ofdm技术,被认为是构建下一代移动通信系统的框架技术。
