排序方式: 共有73条查询结果,搜索用时 15 毫秒
21.
22.
由于通讯技术的迅速发展,手机在生活中已成为人们日日离不开的通讯工具。因此,手机发射电路的设计就尤为重要,它决定着人们发送的信息是否能够迅速、准确、有效的传送到收件人的手机里。手机的整体设计主要分为射频级和基带级,手机的发射电路主要由射频的发射与接收两部分完成。本文主要对手机发射电路的原理进行阐述,同时对手机的常见故障检测进行详细的说明。 相似文献
23.
24.
25.
26.
27.
28.
化工过程模拟及相关高新技术(Ⅰ)化工过程稳态模拟 总被引:19,自引:1,他引:19
化工过程稳态模拟又称静态模拟或离线模拟[1~16](Steady State Simulation,off-line Simulation).通常所说的化工过程模拟或流程模拟多指稳态模拟.它是根据化工过程的稳态数据,诸如物料的压力、温度、流量、组成和有关的工艺操作条件、工艺规定、产品规格以及一定的设备参数,如蒸馏塔的板数、进料位置等,采用适当的模拟软件,用计算机模拟实际的稳态生产过程,得出详细的物料平衡和热量平衡.其中包括人们最为关心的原材料消耗、公用工程消耗和产品、副产品的产量和质量等重要数据.简言之,化工过程模拟就是在计算机上"再现"实际的生产过程.由于这一"再现"过程并不涉及到实际装置的任何管线、设备以及能源的变动,因而给了化工模拟人员最大的自由度,可以在计算机上"为所欲为"地进行不同方案和工艺条件的探讨、分析.并且化工过程模拟所需的成本以及完成一定研究任务所需的时间也是任何实验研究所无法比拟的,因而化工过程稳态模拟已成为研究、开发、设计、挖潜改造、节能增效、生产指导以至于企业管理等工作必不可少的工具,并且在科研和实际生产中发挥着愈来愈大的作用. 相似文献
29.
30.
Most studies on investment evaluation mainly focus on enterprise economic benefits only, without process operability and sustainability considered. In this paper, we suggest that investment evaluation in process industries should be executed under three strategic objectives--enterprise benefits, social benefits and customer benefits. A systematic investment evaluation and decision-making method with a four-step procedure based on the analytic hierarchy process (AHP) is proposed to evaluate various qualitative and quantitative elements with various criteria. At the first step, the decision hierarchy is constructed under the three strategic objectives. Second, pair-wise comparison is utilized to evaluate the weights of elements and criteria. Third, qualitative elements are quantified by pair-wise comparison and quantitative elements are re-scaled by a uniform criterion. At the last, the best choice is made through synthesizing values upward in the hierarchy. An investment decision support system (DSS) is developed based on Microsoft Excel, and applied to a retrofit investment of united fluid catalytic cracking(FCC) and liquefied gas separation process in a refinery plant. 相似文献