题目内容
数据存储在磁盘上的排列方式会影响I/O服务的总时间。假设每个磁道划分成10个物理块，每块存放1个逻辑记录。逻辑记录R1，R2，…，R10存放在同一个磁道上，记录的安排顺序如下表所示。逻辑记录在磁盘中的安排顺序表物理块12345678910逻辑记录R1R2R3R4R5R6R7R8R9R10 假定磁盘的旋转速度为20ms/周，磁头当前处在R1的开始处。若系统顺序处理这些记录，使用单缓冲区，每个记录处理时间为4ms，则处理这10个记录的最长时间为______；若对信息存储进行优化分布后，处理10个记录的最少时间为______。 在局域网参考模型中，下面的 与具体的局域网所采用的媒体访问控制方法类型无关。
查看答案
搜索结果不匹配？点我反馈
更多问题
In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet. With the implementation of 5 , the so - called network has become a reality. The provision of such facilities is the most important part of the network requirements. However, in many applications the communicating computers may be of different types. This means that they may use different programming languages and, more importantly, different forms of 6 interface between user(application) program, normally referred to, as application processes, and the underlying communication services may be 7 . For example, one computer may be a small single - user computer, while another may be a large 8 system. In the earlier days of computer communication, these issues meant that only closed communities of computers (that is, from the same manufacturer) could communicate with each other in a meaningful way. IBM’s Systems Network Architecture (SNA) and DEC’s Digital Network Architecture (DNA) are just two examples of communication software packages produced by manufacturers to allow their systems to be interconnected together. These proprietary packages, however, of which there am still many inexistence, do not address the problem of universal interconnect ability, or open systems interconnection. In an attempt to alleviate this problem, 9 , in the late 1970s, formulated a reference model to provide a common basis (or the coordination of standards developments and to allow existing and evolving standards activities to be placed into perspective with one another.
假设某磁盘的每个磁道划分成11个物理块，每块存放1个逻辑记录。逻辑记录R0，R1，...，R9，R10存放在同一个磁道上，记录的存放顺序如下表所示：物理块1234567891011逻辑记录R0R1R2R3R4R5R6R7R8R9R10 如果磁盘的旋转周期为33ms，磁头当前处在R0的开始处。若系统使用单缓冲区顺序处理这些记录，每个记录处理时间为3ms，则处理这11个记录的最长时间为______；若对信息存储进行优化分布后，处理11个记录的最少时间为______。
有八种化学药品A、B、C、D、W、X、Y、Z要装箱运输。虽然量不大，仅装1箱也装不满，但出于安全考虑，有些药品不能同装一箱。在下表中，符号“×”表示相应的两种药品不能同装一箱。运输这八种化学药品至少需要装 39 箱，实现这种最少箱数的装箱方案(不计装箱顺序)可有 40 个。A B C× D ×× W × X×× × Y ×××× Z×× × ABCDWXYZ
在Web服务技术体制中，______是实现服务组合的事实标准。服务组合过程中需要提供对Web服务多种高级特性的支持，通常采取制定规范，对SOAP消息进行扩展的方式实现。例如，规范______通过对SOAP消息的扩展，实现Web服务的安全性。 数列X1，X2，…，XP存在极限可以表述为：对任何ε＞0，有N＞0，使任何n，m＞N，有│Xn-Xm＜ε。数列X1，X2，…，XP不存在极限可以表述为 。
微信支付 
支付宝支付