Thirdly , a modified extended chirp scaling ( ecs ) algorithm is presented , which solves the problem of producding fine focused images in the class of chirp scaling ( cs ) algorithm . lt can be used for uwb - sar imaging effectively . the phas e error produced by cs operation are analyzed . a windowed process in two dimension frequency domain before cs operation are proposed . it can improve the quality of image and widen the effectively swath and increase the peak to sidelobe ratio ( pslr ) 然后针对chirpscaling ( cs )类算法不能对参考点精确聚焦的问题，提出了一种改进的扩展cs ( ecs )算法，实现了对uwb - sar的高效成像；分析了cs操作产生的相位误差，提出在cs操作之前在二维频率域对信号加窗，除有效提高信号的峰值旁瓣比( pslr )外，还可以提高图像质量，增加有效测绘带宽度。
Since the second half of 2001 unilateral to drop , especially 2002 so far floating implementation of commission , securities business go through from sudden huge profits the periods brilliance to nowadays face for awkward situation of crisis . the department i am working for , it is the typical representative that in short development for several decades , adopt the traditional " the passway is made " service mode , it has gone through from peak to low ebb 我国证券经纪业务在市场发展之初受到政府的特别保护,均采用“通道制”服务模式,导致了券商卖方市场中行为方式的坐商性,这种属于“靠天吃饭”的运营模式,实质是自身没有核心竞争力。虽然业内在实践中也有一些经营模式的创新,但依然没有摆脱传统通道服务模式的限制。
As far as the choice of the 1c is concerned , the pfc and pwm controller combo that is popular at the present time is chosen , because it can simplify designs and being synchronized trigger mode adopted , it can make peak to peak ripple voltage much small even on the condition of small capacitance 在功率因数校正芯片的选择上，选用了国际上比较流行的pfc pwm复合芯片，这种芯片不仅可以简化设计，而且由于采用上升沿下降沿触发方式，在输出滤波电容很小的情况下依然可以得到很小的电压纹波。
Space - time block codes ( stbc ) based on orthogonal design has attracts enough attentions in its applications in mimo - ofdm systems for its full diversity exploiting and low coding / decoding complexity . these applications include not only system performance improvement , but also reduction of the peak to average power ratio in mimo - ofdm systems . under these backgrounds , this paper first studies space - time block codes under the single carrier , flat fading situation , discusses the encoding / decoding principle and its performance under different channels . then , the author focused on the performance of space - time codes under time selective and frequency selective channels , uncovered the fundamental cause of how maximum doppler shift and power delay profile influences the performance of space - time codes through deduction and simulation 在上述背景下,本文以单载波,平坦衰落信道下的空时分组码为切入点,深入分析了其编译码原理和在不同信道情况下的性能;以此为基础,后文展开了对空时分组码在多载波,时间选择性和频率选择性衰落信道下的性能研究,通过理论推导和充分的仿真,揭示了空时/频分组码在时频选择性衰落信道中的性能变化的根本原因;在以上对多载波系统中空时分组码的研究的过程中,作者发现了空时分组码在降低系统峰平比方面应用的可行性,提出了一种降低峰平比的新方法。
Direct current , peak to peak amplitude of the measured quantity is implemented . the whole system has the integrated functions of data process , communicate , display , etc . during designing the hardware , in order to improve the whole system ’ s interference immunity , the advantages of small outline ( so ) chip is fully considered by proper redistribution , the analog parts and digital parts are separated by optoelectronic isolator to reduce the interaction 本课题根据黑龙江省计量研究院的要求,依据最新测量理论设计了直流测量模块,其性能已经达到了万分之一的精度,实现了一个集直流电压、直流电流及峰峰值测量于一体,具有数据处理、通讯、显示等功能的单片机测试系统。
A mobile post office commenced service today ( monday , 11 april 2005 ) in the pedestrian area of findlay road , the peak to temporarily replace the existing peak post office located at shop 302 , level 3 , the peak tower , which has to be closed for business due to the imminent renovation to be carried out at the peak tower 位于山顶芬梨道行人专用区的流动邮政局明日（四月十一日）投入服务，以代替因山顶凌霄阁进行维修工程，而需要暂时关闭的山顶邮政局（山顶道128号凌霄阁第3层302号） 。
