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代表当今印刷制版业潮流的CTP技术的应用,在欧、美等地区发达国家得到快速普及。我国CTP技术的应用随着我国经济的发展,越来越被印刷制版界所接受,到目前为止,我国有400多台CTP机投入使用。随着CTP技术的进一步完善、成熟,CTP机价格的下调、国产CTP版材的大量投放市场,我国将有更多的印刷制版厂应用CTP技术。 相似文献
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丹江是汉江的重要支流,水力资源较为丰富,在河南省境内丹江干流上建有两座小型水电站,水力发电效益较好,但对下游河道生态造成了不利影响。本文根据实测流量资料,采用水文学方法进行河道生态流量计算,提出丹江干流水电站下泄生态流量要求及保障措施,为丹江河南段的水生态保护提供借鉴和参考。 相似文献
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本文主要论述了乳剂熔化过程中光谱增感、过滤精度和静置时间等因素对印刷胶片性能的影响,归纳出印刷胶片生产的一个优选方案. 相似文献
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Cognitive Radio (CR) is an emerging technology used to significantly improve the efficiency of spectrum utilization. Although some spectrum bands in the primary user’s licensed spectrum are intensively used, most of the spectrum bands remain underutilized. The introduction of open spectrum and dynamic spectrum access lets the secondary (unlicensed) users, supported by cognitive radios; opportunistically utilize the unused spectrum bands. However, if a primary user returns to a band occupied by a secondary user, the occupied spectrum band is vacated immediately by handing off the secondary user’s call to another idle spectrum band. Multiple spectrum handoffs can severely degrade quality of service (QoS) for the interrupted users. To avoid multiple handoffs, when a licensed primary user appears at the engaged licensed band utilized by a secondary user, an effective spectrum handoff procedure should be initiated to maintain a required level of QoS for secondary users. In other words, it enables the channel clearing while searching for target vacant channel(s) for completing unfinished transmission. This paper proposes prioritized proactive spectrum handoff decision schemes to reduce the handoff delay and the total service time. The proposed schemes have been modeled using a preemptive resume priority (PRP) M/G/1 queue to give a high priority to interrupted users to resume their transmission ahead of any other uninterrupted secondary user. The performance of proposed handoff schemes has been evaluated and compared against the existing spectrum handoff schemes. Experimental results show that the schemes developed here outperform the existing schemes in terms of average handoff delay and total service time under various traffic arrival rates as well as service rates. 相似文献
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调洪演算在水库的规划设计以及运行管理中都是十分重要的,试算法是其中一种常用方法。结合工程实际需要,充分利用excel自身的强大功能,采用VBA编程解决了调洪演算的程序化问题,从而提高了计算的速度和精度。 相似文献
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河南省内乡县板厂铜多金属矿矿床成因及成矿模式探讨 总被引:2,自引:0,他引:2
河南省内乡县板厂铜多金属矿区位于秦岭多金属成矿带东段,朱阳关-夏馆断裂带中部,矿体呈不规则脉状产于构造蚀变岩带中.矿石类型有花岗岩类型和蚀变岩类型两种.通过对成矿流体、包体测温、稀土元素、微量元素的测定研究,结合区域成矿背景及矿床成矿条件分析表明:矿床成因应属岩浆期后中低温热液矿床.成矿模式为富含成矿元素的中酸性岩浆沿着朱阳关-夏馆断裂侵入,同时由于挤压作用,导致秦岭群雁岭沟组地层下俯,由岩浆分异后的高盐度成矿流体在上移过程中萃取地层中的成矿元素,在较浅的部位沉淀成矿. 相似文献
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采用电感耦合等离子体质谱法(ICP-MS)测定地球化学样品中痕量Rh时,待测溶液的基体及分子离子干扰严重影响ICP-MS测定103Rh的准确性。实验以10 ng/mL 的175Lu消除基体干扰,以数学校正方程消除多原子离子87Sr16O+、63Cu40Ar+、86SrOH、206Pb2+对103Rh的干扰,最终实现了电感耦合等离子体质谱法测定地球化学样品中痕量Rh。分别详细考察了Cu、Sr、Pb对Rh测定的干扰情况,不仅有效消除了87Sr16O+、63Cu40Ar+、86SrOH多原子离子对103Rh的测定干扰,而且发现了双电荷离子206Pb2+对103Rh的测定存在严重的质谱干扰。同时通过向不同浓度Rh的标准溶液中分别加入不同量的干扰元素Cu、Sr及Pb进行试验,得到了对103Rh元素进行校正的数学校正方程。实验表明,Rh在0.050~100.0 ng/mL范围内与其对应的信号强度呈良好的线性关系,线性相关系数为0.999 9,方法检出限(3σ)为0.014 ng/g。采用实验方法对铂族元素地球化学一级标准物质中Rh进行分析,结果与认定值的相对误差(RE)为-7.27%~6.15%,相对标准偏差(RSD,n=12)均不大于8.6%。将实验方法应用于云南、四川、新疆等地区不同含量贵金属地球化学样品中Rh的测定,所得结果与锡试金方法符合性较好。 相似文献