局域网交换机中英文对照外文翻译文献
中英文资料外文翻译文献
英文:
LAN Switch Architecture
This chapter introduces many of the concepts behind LAN switching common to all switch vendors. The chapter begins by looking at how data are received by a switch, followed by mechanisms used to switch data as efficiently as possible, and concludes with forwarding data toward their destinations. These concepts are not specific to Cisco and are valid when examining the capabilities of any LAN switch.
1. Receiving Data—Switching Modes
The first step in LAN switching is receiving the frame or packet, depending on the capabilities of the switch, from the transmitting device or host. Switches making forwarding decisions only at Layer 2 of the OSI model refer to data as frames, while switches making forwarding decisions at Layer 3 and above refer to data as packets. This chapter's examination of switching begins from a Layer 2 point of view. Depending on the model, varying amounts of each frame are stored and examined before being switched.
Three types of switching modes have been supported on Catalyst switches:
?Cut through
?Fragment free
?Store and forward
These three switching modes differ in how much of the frame is received and examined by the switch before a forwarding decision is made. The next sections describe each mode in detail.
1.1 Cut-Through Mode
Switches operating in cut-through mode receive and examine only the first 6 bytes of a frame. These first 6 bytes represent the destination MAC address of the frame, which is sufficient information to make a forwarding decision. Although cut-through switching offers the least latency when transmitting frames, it is susceptible to transmitting fragments created via Ethernet collisions, runts (frames less than 64 bytes), or damaged frames.
1.2 Fragment-Free Mode
Switches operating in fragment-free mode receive and examine the first 64 bytes of frame. Fragment free is referred to as "fast forward" mode in some Cisco Catalyst documentation. Why examine 64 bytes? In a properly designed Ethernet network, collision fragments must be detected in the first 64 bytes.
1.3 Store-and-Forward Mode
Switches operating in store-and-forward mode receive and examine the entire frame, resulting in the most error-free type of switching.
As switches utilizing faster processor and application-specific integrated circuits (ASICs) were introduced, the need to support cut-through and fragment-free switching was no longer necessary. As a result, all new Cisco Catalyst switches utilize store-and-forward switching.
Figure2-1 compares each of the switching modes.
Figure2-1.Switching Modes
2. Switching Data
Regardless of how many bytes of each frame are examined by the switch, the frame must eventually be switched from the input or ingress port to one or more output or egress ports. A switch fabric is a general term for the communication channels used by the switch to transport frames, carry forwarding decision information, and relay management information throughout the switch. A comparison could be made between the switching fabric in a Catalyst switch and a transmission on an automobile. In an automobile, the transmission is responsible for relaying power from the engine to the wheels of the car. In a Catalyst switch, the switch fabric is responsible for relaying frames from an input or ingress port to one or more output or egress ports. Regardless of model, whenever a new switching platform is introduced, the documentation will generally refer to the "transmission" as the switching fabric.
Although a variety of techniques have been used to implement switching fabrics on Cisco Catalyst platforms, two major architectures of switch fabrics are common:
?Shared bus
?Crossbar
2.1 Shared Bus Switching
In a shared bus architecture, all line modules in the switch share one data path. A central arbiter determines how and when to grant requests for access to the bus from each line card. Various methods of achieving fairness can be used by the arbiter depending on the configuration of the switch. A shared bus architecture is much like multiple lines at an airport ticket counter, with only one ticketing agent processing customers at any given time.
Figure2-2illustrates a round-robin servicing of frames as they enter a switch. Round-robin is the simplest method of servicing frames in the order in which they are received. Current Catalyst switching platforms such as the Catalyst 6500 support a variety of quality of service (QoS) features to provide priority service to specified traffic flows.
Figure 2-2. Round-Robin Service Order
The following list and Figure 2-3 illustrate the basic concept of moving frames from the received port or ingress, to the transmit port(s) or egress using a shared bus architecture:
Frame received from Host1—The ingress port on the switch receives the entire frame from Host1 and stores it in a receive buffer. The port checks the frame's Frame Check Sequence (FCS) for errors. If the frame is defective (runt, fragment, invalid CRC, or Giant), the port discards the frame and increments the appropriate counter.
Requesting access to the data bus—A header containing information necessary to make a forwarding decision is added to the frame. The line card then requests access or permission to transmit the frame onto
the data bus.
Frame transmitted onto the data bus— After the central arbiter grants access, the frame is transmitted onto the data bus.
Frame is received by all ports— In a shared bus architecture, every frame transmitted is received by all ports simultaneously. In addition, the frame is received by the hardware necessary to make a forwarding decision.
Switch determines which port(s) should transmit the frame— The information added to the frame in step 2 is used to determine which ports should transmit the frame. In some cases, frames with either an unknown destination MAC address or a broadcast frame, the switch will transmit the frame out all ports except the one on which the frame was received.
Port(s) instructed to transmit, remaining ports discard the frame— Based on the decision in step 5, a certain port or ports is told to transmit the frame while the rest are told to discard or flush the frame.
Egress port transmits the frame to Host2—In this example, it is assumed that the location of Host2 is known to the switch and only the port connecting to Host2 transmits the frame.
One advantage of a shared bus architecture is every port except the ingress port receives a copy of the frame automatically, easily enabling multicast and broadcast traffic without the need to replicate the frames for each port. This example is greatly simplified and will be discussed in detail for Catalyst platforms that utilize a shared bus architecture in Chapter 3, "Catalyst Switching Architecture."
Figure 2-3. Frame Flow in a Shared Bus
2.2 Crossbar Switching
In the shared bus architecture example, the speed of the shared data bus determines much of the overall traffic handling capacity of the switch. Because the bus is shared, line cards must wait their turns to communicate, and this limits overall bandwidth.
A solution to the limitations imposed by the shared bus architecture is the implementation of a crossbar switch fabric, as shown in Figure 2-4. The term crossbar means different things on different switch platforms, but essentially indicates multiple data channels or paths between line cards that can be used simultaneously.
In the case of the Cisco Catalyst 5500 series, one of the first crossbar architectures advertised by Cisco, three individual 1.2-Gbps data buses are implemented. Newer Catalyst 5500 series line cards have the necessary connector pins to connect to all three buses simultaneously, taking advantage of 3.6 Gbps of aggregate bandwidth. Legacy line cards from the Catalyst 5000 are still compatible with the Catalyst 5500 series by connecting to only one of the three data buses. Access to all three buses is required by Gigabit Ethernet cards on the Catalyst 5500 platform.
A crossbar fabric on the Catalyst 6500 series is enabled with the Switch Fabric Module (SFM) and Switch Fabric Module 2 (SFM2). The SFM provides 128 Gbps of bandwidth (256 Gbps full duplex) to line cards via 16 individual 8-Gbps connections to the crossbar switch fabric. The SFM2 was introduced to support the Catalyst 6513 13-slot chassis and includes architecture optimizations over the SFM.
Figure 2-4. Crossbar Switch Fabric
3. Buffering Data
Frames must wait their turn for the central arbiter before being transmitted in shared bus architectures. Frames can also potentially be delayed when congestion occurs in a crossbar switch fabric. As a result, frames must be buffered until transmitted. Without an effective buffering scheme, frames are more likely to be dropped anytime traffic oversubscription or congestion occurs.
Buffers get used when more traffic is forwarded to a port than it can transmit. Reasons for this include the following:
?Speed mismatch between ingress and egress ports
?Multiple input ports feeding a single output port
?Half-duplex collisions on an output port
? A combination of all the above
To prevent frames from being dropped, two common types of memory management are used with Catalyst switches:
?Port buffered memory
?Shared memory
3.1 Port Buffered Memory
Switches utilizing port buffered memory, such as the Catalyst 5000, provide each Ethernet port with a certain amount of high-speed memory to buffer frames until transmitted. A disadvantage of port buffered memory is the dropping of frames when a port runs out of buffers. One method of maximizing the benefits of buffers is the use of flexible buffer sizes. Catalyst 5000 Ethernet line card port buffer memory is flexible and can create frame buffers for any frame size, making the most of the available buffer memory. Catalyst 5000 Ethernet cards that use the SAINT ASIC contain 192 KB of buffer memory per port, 24 kbps for receive or input buffers, and 168 KB for transmit or output buffers.
Using the 168 KB of transmit buffers, each port can create as many as 2500 64-byte buffers. With most of the buffers in use as an output queue, the Catalyst 5000 family has eliminated head-of-line blocking issues. (You learn more about head-of-line blocking later in this chapter in the section "Congestion and Head-of-Line Blocking.") In normal operations, the input queue is never used for more than one frame, because the switching bus runs at a high speed.
Figure 2-5illustrates port buffered memory.
Figure 2-5. Port Buffered Memory
3.2 Shared Memory
Some of the earliest Cisco switches use a shared memory design for port buffering. Switches using a shared memory architecture provide all ports access to that memory at the same time in the form of shared frame or packet buffers. All ingress frames are stored in a shared memory "pool" until the egress ports are ready to transmit. Switches dynamically allocate the shared memory in the form of buffers, accommodating ports with high amounts of ingress traffic, without allocating unnecessary buffers for idle ports.
The Catalyst 1200 series switch is an early example of a shared memory switch. The Catalyst 1200 supports both Ethernet and FDDI and has 4 MB of shared packet dynamic random-access memory (DRAM). Packets are handled first in, first out (FIFO).
More recent examples of switches using shared memory architectures are the Catalyst 4000 and 4500 series switches. The Catalyst 4000 with a Supervisor I utilizes 8 MB of Static RAM (SRAM) as dynamic frame buffers. All frames are switched using a central processor or ASIC and are stored in packet buffers until
switched. The Catalyst 4000 Supervisor I can create approximately 4000 shared packet buffers. The Catalyst 4500 Supervisor IV, for example, utilizes 16 MB of SRAM for packet buffers. Shared memory buffer sizes may vary depending on the platform, but are most often allocated in increments ranging from 64 to 256 bytes. Figure 2-6 illustrates how incoming frames are stored in 64-byte increments in shared memory until switched by the switching engine.
Figure 2-6. Shared Memory Architecture
4. Oversubscribing the Switch Fabric
Switch manufacturers use the term non-blocking to indicate that some or all the switched ports have connections to the switch fabric equal to their line speed. For example, an 8-port Gigabit Ethernet module would require 8 Gb of bandwidth into the switch fabric for the ports to be considered non-blocking. All but the highest end switching platforms and configurations have the potential of oversubscribing access to the switching fabric.
Depending on the application, oversubscribing ports may or may not be an issue. For example, a 10/100/1000 48-port Gigabit Ethernet module with all ports running at 1 Gbps would require 48 Gbps of bandwidth into the switch fabric. If many or all ports were connected to high-speed file servers capable of generating consistent streams of traffic, this one-line module could outstrip the bandwidth of the entire switching fabric. If the module is connected entirely to end-user workstations with lower bandwidth requirements, a card that oversubscribes the switch fabric may not significantly impact performance. Cisco offers both non-blocking and blocking configurations on various platforms, depending on bandwidth requirements. Check the specifications of each platform and the available line cards to determine the aggregate bandwidth of the connection into the switch fabric.
5. Congestion and Head-of-Line Blocking
Head-of-line blocking occurs whenever traffic waiting to be transmitted prevents or blocks traffic destined elsewhere from being transmitted. Head-of-line blocking occurs most often when multiple high-speed data sources are sending to the same destination. In the earlier shared bus example, the central arbiter used the round-robin service approach to moving traffic from one line card to another. Ports on each line card request access to transmit via a local arbiter. In turn, each line card's local arbiter waits its turn for the central arbiter to grant access to the switching bus. Once access is granted to the transmitting line card, the central arbiter has to wait for the receiving line card to fully receive the frames before servicing the next request in line. The situation is not much different than needing to make a simple deposit at a bank having one teller and many lines, while the person being helped is conducting a complex transaction.
In Figure 2-7, a congestion scenario is created using a traffic generator. Port 1 on the traffic generator is connected to Port 1 on the switch, generating traffic at a 50 percent rate, destined for both Ports 3 and 4. Port 2 on the traffic generator is connected to Port 2 on the switch, generating traffic at a 100 percent rate, destined for only Port 4. This situation creates congestion for traffic destined to be forwarded by Port 4 on the switch because traffic equal to 150 percent of the forwarding capabilities of that port is being sent. Without proper buffering and forwarding algorithms, traffic destined to be transmitted by Port 3 on the switch may have to wait until the congestion on Port 4 clears.
Figure 2-7. Head-of-Line Blocking
Head-of-line blocking can also be experienced with crossbar switch fabrics because many, if not all, line
cards have high-speed connections into the switch fabric. Multiple line cards may attempt to create a connection to a line card that is already busy and must wait for the receiving line card to become free before transmitting. In this case, data destined for a different line card that is not busy is blocked by the frames at the head of the line.
Catalyst switches use a number of techniques to prevent head-of-line blocking; one important example is the use of per port buffering. Each port maintains a small ingress buffer and a larger egress buffer. Larger output buffers (64 Kb to 512 k shared) allow frames to be queued for transmit during periods of congestion. During normal operations, only a small input queue is necessary because the switching bus is servicing frames at a very high speed. In addition to queuing during congestion, many models of Catalyst switches are capable of separating frames into different input and output queues, providing preferential treatment or priority queuing for sensitive traffic such as voice. Chapter 8 will discuss queuing in greater detail.
6. Forwarding Data
Regardless of the type of switch fabric, a decision on which ports should forward a frame and which should flush or discard the frame must occur. This decision can be made using only the information found at Layer 2 (source/destination MAC address), or on other factors such as Layer 3 (IP) and Layer 4 (Port). Each switching platform supports various types of ASICs responsible for making the intelligent switching decisions. Each Catalyst switch creates a header or label for each packet, and forwarding decisions are based on this header or label. Chapter 3 will include a more detailed discussion of how various platforms make forwarding decisions and ultimately forward data.
7. Summary
Although a wide variety of different approaches exist to optimize the switching of data, many of the core concepts are closely related. The Cisco Catalyst line of switches focuses on the use of shared bus, crossbar switching, and combinations of the two depending on the platform to achieve very high-speed switching solutions. High-speed switching ASICs use shared and per port buffers to reduce congestion and prevent head-of-line blocking.
翻译：
局域网交换机体系结构
本章将介绍所有交换机生产厂商都遵守的局域网交换技术的一些基本概念。本章首先介绍交换机如何接受数据。随后，本章介绍保证高效数据交换的一些机制。最后，本章介绍如何将数据转发给目标。这些概念并非Cisco交换机所特有的，而是在查看局域网交换机功能的时候，对所有交换机产品都适用的。
1. 数据接收----交换模式
在局域网交换中，根据交换机功能的不同，第一步就是从发送设备或主机接收帧或分组。对于仅在OSI模型的第2层进行转发决策的交换机，它们将数据看作帧。而对于在OSI 模型的第3层或者更高层进行转发决策的交换机，它们将数据看作分组。本章首先从第2层的角度来研究交换机。根据具体型号的不同，交换机在数据交换之前所存储和检查的桢数目也存在一定差异。
Catalyst交换机攴持下述三种交换模式:
?直通模式；
?碎片隔离模式；
?存储转发模式。
上述3种交换模式的区别在于交换机在制定转发决策之前所接收和检查的帧数目。下面将详细讨论每种交换模式。
1.1 直通模式
如果交换机工作在直通模式，那么它将只接收和检查帧的的前6个字节。这6个字节代表了帧的日标MAC地址,交换机利用这些信息足以做出转发决策。尽管直通交换能够在数据传送的时候提供最低的延迟,但却容易传送以太网碰撞所产生的碎片、残帧(runt)或受损帧。
1.2 碎片隔离模式
如呆交换机工作在碎片隔离模式,那么它将接收和检查全帧的前64个字节。在某些Cisco Catalyst交换机的文档中,碎片隔离又称为“快速转发”模式。为什么交换机检查帧的前64个字节呢?因为在设计良好的以太网网络中,碰撞碎片必须在前64字节中检测出来。
1.3 存储转发模式
如果交换机工作在存储转发模式,那么它将接收和检查整帧,因此它是错误率最低的交换模式。
由于采用速度更快的处理器和ASIC（Application-Specific Integrated Circuit，专用集成电路），交换机不必支持直通交换机和碎片隔离交换，因此，所有新型的Cisco Catalyst交换机都采用存储转发交换。
图2-1比较各种交换模式之间的区别。
图2-1 交换模式
2. 数据交换
无论交换机需要检查帧的多少字节，帧最终都将由输入或入站端口交换到单个或多个输出和出站端口。交换矩阵(switch fabric)是交换机通信信道的一个常用术语,它可以在交换机内部传送帧、承载转发决策信虑、和转送管理信息。Catalyst交换机中的交换矩阵可以看作汽车中的传动装置，在汽车中,传动装置负责将引擎的动力传递给汽车轮子；在Catalyst交换机中，交换矩阵负责将输入或入站端口的帧转送给单个或多个输出和出站端口。无论具体型号如何，也无论何时产生新的交换平台,所有文档都会将“传动装置”作为交换矩阵。
尽管Cisco Catalyst平台已经采用多种技术来实现交换矩阵，但以下两种体系结构的交换矩阵最为常见：
?共享总线；
?交叉矩阵。
2.1 共享总线交换
在共享总线的体系结构中，交换机的所有线路模块都共享1个数据通路。中央仲裁器决定何时授予各线路卡访问总线的请求。根据交换机配置的情况，仲裁器能够使用多种公平方法。共享总线体系结构非常类似于机场票务柜台前的多个队列，但任何时候仅有1个票务代理处理客户请求。
图2-2举例说明帧进入交换机时的循环服务过程。如果希望根据帧的接收顺序进行服务，那么循环是最简单的方法。为了能够给特定通信流量提供优先级服务，当前的Catalyst 交换平台（例如Catalyst 6500）能够支持各种各样的QoS（Quanlity Of Service，服务质量）特性。
图2-2 循环服务顺序
图2-3说明了共享总线体系结构中将接收端口或入口处的帧移动到发送端口或出口的基本原理,其中各步骤说明如下。
1.接收源自主机1的帧----交换机的入站端口接受源自主机1的整帧，并且将其存储到接受缓冲区中。端口根据帧的FCS（Frame Check Sequence，帧检验序列）进行错误检测。如果帧存在缺陷（例如残帧、碎片、无效CRC或者巨型帧），那么端口将丢弃该帧，并且将增加相关计数器的数值。
2.请求访问数据总线----包含转发决策所需要的信息报头将被添加到帧中，然后线路卡请求在数据总线上发送帧的访问权限或者许可权限。
图2-3 共享总线中的帧流
3.将帧发送到数据总线----在中央仲裁器授予访问权限之后, 帧将被发送到数据总线上。
4.所有端口接收到帧----在共享总线体系结构中，所有端口都将同时接收每个发送帧。此外，负责转发决策的硬件也将接收到帧。
5.交换机决定哪个端口应当发送帧----第2步骤中添加到帧中的信息可用于确定哪些端口应当发送帧。在某些情况下，对于具有未知目标MAC地址的帧或者广播帧，交换机将向除帧接收端口之外的所有端口发送帧。
6.端口发送帧,其余端口丢弃该帧----根据第5步骤中的决策，某个特定端口或者某些端口被告知发送帧，而其余端口则被告知丢弃或者清空帧。
7.出站端口将帧发送到主机2----在这个示例中，假定交换机知道主机2的位置，并且仅在连接到主机2的端口发送帧。
共享总线体系结构的优势之一在于每个端口（入站端口除外）都将自动接收帧的副本，也就易于实现组播和广播流量，而无需复制各个端口的帧。
2.2 交叉矩阵交换
在共享总线体系结构示例中，共享数据总线的速度决定了交换机的流量处理总容量。因为总线采用共享访问的方式，所以线路卡必须等待时机才能进行通信，这严重限制了总带宽。
为了克服共享数据总线体系结构所产生的限制，解决方案是采用交叉交换矩阵，如图2-4所示。对于不同的交换机平台，术语交叉矩阵意味着不同的内容，但基本都指线路卡之间能够同时使用多个数据信道或者通路。
图2-4 交叉交换矩阵
在Cisco Catalyst 5500系列（Cisco公司最早采用交叉矩阵体系结构的产品之一）交换机产品中，总共实现3条独立的1.2Gbit/s数据总线，新型的Catalyst 5500系列线路卡具有必要的连接器针脚，她们能够同时连接到这3条数据总线，进而能够充分利用3.6Gbit/s 的总带宽。通过仅连接到3条数据总线中的1条数据总线，老式的Cisco Catalyst 5500系列线路卡仍然能够兼容Cisco Catalyst 5500系列。在Cisco Catalyst 5500平台中，吉比特以太网线路卡要求访问所有3条数据总线。
在Cisco Catalyst 6500系列交换机中，SFM（Switch Fabric Module，交换矩阵模块）和SFM2（Switch Fabric Module2，交换矩阵模块2）能够支持交叉矩阵。通过到交叉交换矩阵的16个独立的8Gbit/s连接，SFM能够向线路卡提供128Gbit/s的带宽（256Gbit/s 全双工）。新型SFM2用于支持Catalyst 6513（13插槽的机箱），并且对SFM进行了体系结构方面的优化。
3. 数据缓冲
在共享数据体系结构传送帧之前，帧必须等待中央仲裁器的处理安排。此外，交叉交换矩阵发生拥塞，也可能会延迟帧的处理。基于上述原因，在传送帧之前，必须对其进行缓冲处理。如果没有有效的缓冲机制，那么当出现流景过量或发牛拥塞的时候,帧被丢弃的可能性就非常高。
如果发往端口的流量超过了它所能发送的流量,那么就需要使用缓冲。出现下述情况的时
候，就需要使用缓冲：
?入口和出站端口的速度不匹配；
?多个输入端口共同向单个输出端口提供流景；
?输出端口发生半双工碰撞；
?上述几种情况的组合。
为了防止丢弃帧,Catalyst交换机通常采用下述两种内存管理方式：
?端口缓冲内存；
?共享内存。
3.1 端口缓冲内存
通过采用端口缓冲内存，交换机(例如Catalyst 5500)能够为每个以太网端口提供一定数量的高速内存，这些内存可用于帧发送之前的帧缓冲。端口缓冲内存的不足之处，在于如果端口的缓冲已经用尽，那么就会发生丢弃帧的情况。为了最大限度利用缓冲的优势，方法之一是采用灵活的缓冲区尺寸。Catalyst 5500以太网线路卡端口的缓冲内存就是非常灵活的，并且能够创建各种尺寸的帧缓冲区，进而充分利用可用的缓冲区内存。对于采用SAINT ASIC的Catalyst 5000以太网卡，每个端口包含192KB的缓冲区内存，其中24KB用于接收或者输入缓冲区，而168KB用于发送或者输出缓冲区。
通过使用168KB的发送缓冲区，每个端口最多能够创建2500个64字节的缓冲区。因为大多数缓冲区都用语输出队列，所以Catalyst 5000家族交换机已经减轻线端阻塞的问题。
图2-5举例说明端口缓冲内存的情况。
3.2 共享内存
在最早的Cisco交换机产品中，某些产品使用共享内存设计进行端口缓冲。对于采用共享内存体系结构的交换机，所有端口能够同时以共享帧或者分组缓冲区的形式访问内存。所有的入口帧都被存储到共享内存“池”中，并且一直保存到出站端口准备发送帧为止。交换机以缓冲区的形式动态地分配共享内存，为接收大量入口流量的端口分配足够的缓冲区，并且不会为空闲端口分配不必要的缓冲区。
图2-5 端口缓冲内存
Catalyst 1200系列交换机是一款早期的共享内存交换机产品。Catalyst 1200能够支持以太网和FDDI，并且具有4MB的共享分组DRAM（Dynamic Random-Access Memory，动态随机访问内存）。分组采用FIFO（first in ，first out，先入先出）的处理方式。
在采用共享内存体系结构的交换机中，Catalyst 4000和Catalyst 4500系列交换机是比较新的一些产品。对于采用Supervisor 1的Catalyst 4000系列，它采用8MB的SRAM（Static Random-Access Memory，静态随机访问内存）作为动态帧缓冲区。中央处理器或者ASIC 负责帧交换，并且在交换之前将把帧存储到分组缓冲区内。Catalyst 4500 Supervisor IV
中英文参考文献格式
中文参考文献格式 参考文献（即引文出处）的类型以单字母方式标识： M——专著，C——论文集，N——报纸文章，J——期刊文章，D——学位论文，R——报告，S——标准，P——专利；对于不属于上述的文献类型，采用字母“Z”标识。 参考文献一律置于文末。其格式为： （一）专著 示例 [1] 张志建.严复思想研究[M]. 桂林：广西师范大学出版社，1989. [2] 马克思恩格斯全集：第1卷[M]. 北京：人民出版社，1956. [3] [英]蔼理士.性心理学[M]. 潘光旦译注.北京：商务印书馆，1997. （二）论文集 示例 [1] 伍蠡甫.西方文论选[C]. 上海：上海译文出版社，1979. [2] 别林斯基.论俄国中篇小说和果戈里君的中篇小说[A]. 伍蠡甫.西方文论选：下册[C]. 上海：上海译文出版社，1979. 凡引专著的页码，加圆括号置于文中序号之后。 （三）报纸文章 示例 [1] 李大伦.经济全球化的重要性[N]. 光明日报，1998-12-27，（3） （四）期刊文章 示例 [1] 郭英德.元明文学史观散论[J]. 北京师范大学学报（社会科学版），1995（3）. （五）学位论文 示例 [1] 刘伟.汉字不同视觉识别方式的理论和实证研究[D]. 北京：北京师范大学心理系，1998. （六）报告 示例 [1] 白秀水，刘敢，任保平. 西安金融、人才、技术三大要素市场培育与发展研究[R]. 西安：陕西师范大学西北经济发展研究中心，1998. （七）、对论文正文中某一特定内容的进一步解释或补充说明性的注释，置于本页地脚，前面用圈码标识。 参考文献的类型 根据GB3469-83《文献类型与文献载体代码》规定，以单字母标识： M——专著（含古籍中的史、志论著） C——论文集 N——报纸文章 J——期刊文章 D——学位论文 R——研究报告 S——标准 P——专利 A——专著、论文集中的析出文献 Z——其他未说明的文献类型 电子文献类型以双字母作为标识： DB——数据库 CP——计算机程序 EB——电子公告
中英文论文对照格式
英文论文APA格式 英文论文一些格式要求与国内期刊有所不同。从学术的角度讲，它更加严谨和科学，并且方便电子系统检索和存档。 版面格式
表格 表格的题目格式与正文相同，靠左边，位于表格的上部。题目前加Table后跟数字，表示此文的第几个表格。 表格主体居中，边框粗细采用0.5磅；表格内文字采用Times New Roman，10磅。 举例： Table 1. The capitals, assets and revenue in listed banks
图表和图片 图表和图片的题目格式与正文相同，位于图表和图片的下部。题目前加Figure 后跟数字，表示此文的第几个图表。图表及题目都居中。只允许使用黑白图片和表格。 举例： Figure 1. The Trend of Economic Development 注：Figure与Table都不要缩写。 引用格式与参考文献 1. 在论文中的引用采取插入作者、年份和页数方式，如"Doe (2001, p.10) reported that …" or "This在论文中的引用采取作者和年份插入方式，如"Doe (2001, p.10) reported that …" or "This problem has been studied previously (Smith, 1958, pp.20-25)。文中插入的引用应该与文末参考文献相对应。 举例：Frankly speaking, it is just a simulating one made by the government, or a fake competition, directly speaking. (Gao, 2003, p.220). 2. 在文末参考文献中，姓前名后，姓与名之间以逗号分隔；如有两个作者，以and连接；如有三个或三个以上作者，前面的作者以逗号分隔，最后一个作者以and连接。 3. 参考文献中各项目以“点”分隔，最后以“点”结束。 4. 文末参考文献请按照以下格式：
机械加工刀具几何形状论文中英文资料对照外文翻译
中英文资料对照外文翻译文献综述 附录1： 英文原文 Selection of optimum tool geometry and cutting conditions using a surface roughness prediction model for end milling Abstract Influence of tool geometry on the quality of surface produced is well known and hence any attempt to assess the performance of end milling should include the tool geometry. In the present work, experimental studies have been conducted to see the effect of tool geometry (radial rake angle and nose radius) and cutting conditions (cutting speed and feed rate) on the machining performance during end milling of medium carbon steel. The first and second order mathematical models, in terms of machining parameters, were developed for surface roughness prediction using response surface methodology (RSM) on the basis of experimental results. The model selected for optimization has been validated with the Chi square test. The significance of these parameters on surface roughness has been established with analysis of variance. An attempt has also been made to optimize the surface roughness prediction model using genetic algorithms (GA). The GA program gives minimum values of surface roughness and their respective optimal conditions. 1 Introduction End milling is one of the most commonly used metal removal operations in industry because of its ability to remove material faster giving reasonably good surface quality. It is used in a variety of manufacturing industries including aerospace and automotive sectors, where quality is an important factor in the production of slots, pockets, precision moulds and dies. Greater attention is given to dimensional accuracy and surface roughness of products by the industry these days. Moreover, surface finish influences mechanical properties such as fatigue behaviour, wear, corrosion, lubrication and electrical conductivity. Thus, measuring and characterizing surface finish can be considered for predicting machining performance. Surface finish resulting from turning operations has traditionally received considerable research attention, where as that of machining processes using multipoint cutters, requires attention by researchers. As these processes involve large number of parameters, it would be difficult to correlate surface finish with other parameters just by conducting experiments. Modelling helps to understand this kind of process better. Though some amount of work has
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操作CNC刀具磨床常用词汇中英文对照一、一般词汇 grinding 磨削 regrinding 修磨 production 生产、制造 grinding machine 磨床 grinding wheel 砂轮 diamond grinding wheel 金刚石砂轮 CBN grinding wheel 立方碳化硼砂轮 spindle 主轴 axis 轴 carbide 硬质合金 high speed steel (HSS) 高速钢 work piece 工件 二、菜单中常用词 menu 菜单 management 管理 system 系统 database 数据库 data 数据 file 文件 automatic 自动 semi-automatic 半自动 manual 手动 calculation 计算 initialize 初始化 transfer 传输 generation 产生、生成 cycle 循环 simulation 模拟 parameter 参数 screen 屏幕、显示屏 display 显示 standard 标准 zoom 缩放 selection 选择
identifier 区别、识别procedure 过程 safety zone 安全区 feed 进给 rotation 旋转 coolant valve 冷却液阀门 release angel 释让角 machining 加工 roughing 粗加工 finishing 精加工 polishing 超细加工（抛光）measuring 测量 measuring probe 测量头 geometry 几何参数 position 位置 default 预设值 exist 存在 value 值 distance 距离 diameter 直径 length 长度 radius 半径 width 宽度 height 高度 depth 深度 cylinder 圆柱体 core diameter 芯厚（直径） step diameter 阶梯直径 radial 径向 periphery 周向、周边 straight 直的 curve 曲线 positive 正的 negative 负的 right 右边 left 左边 rear 尾部 minus 减 plus 加 longitudinal 纵向（砂轮与刃平行）traverse 横向（砂轮与刃垂直）
中英文论文参考文献标准格式 超详细
超详细中英文论文参考文献标准格式 1、参考文献和注释。按论文中所引用文献或注释编号的顺序列在论文正文之后，参考文献之前。图表或数据必须注明来源和出处。 （参考文献是期刊时，书写格式为： [编号]、作者、文章题目、期刊名（外文可缩写）、年份、卷号、期数、页码。参考文献是图书时，书写格式为： [编号]、作者、书名、出版单位、年份、版次、页码。） 2、附录。包括放在正文内过份冗长的公式推导，以备他人阅读方便所需的辅助性数学工具、重复性数据图表、论文使用的符号意义、单位缩写、程序全文及有关说明等。 参考文献（即引文出处）的类型以单字母方式标识，具体如下： [M]--专著,著作 [C]--论文集(一般指会议发表的论文续集，及一些专题论文集，如《***大学研究生学术论文集》[N]-- 报纸文章 [J]--期刊文章：发表在期刊上的论文，尽管有时我们看到的是从网上下载的（如知网），但它也是发表在期刊上的，你看到的电子期刊仅是其电子版 [D]--学位论文：不区分硕士还是博士论文 [R]--报告：一般在标题中会有"关于****的报告"字样 [S]-- 标准 [P]--专利 [A]--文章：很少用，主要是不属于以上类型的文章 [Z]--对于不属于上述的文献类型，可用字母"Z"标识，但这种情况非常少见 常用的电子文献及载体类型标识： [DB/OL] --联机网上数据(database online) [DB/MT] --磁带数据库(database on magnetic tape) [M/CD] --光盘图书(monograph on CDROM) [CP/DK] --磁盘软件(computer program on disk) [J/OL] --网上期刊(serial online) [EB/OL] --网上电子公告(electronic bulletin board online) 很显然，标识的就是该资源的英文缩写，/前面表示类型，/后面表示资源的载体，如OL表示在线资源 二、参考文献的格式及举例 1．期刊类 【格式】[序号]作者.篇名[J].刊名,出版年份,卷号(期号)起止页码. 【举例】 [1] 周融，任志国，杨尚雷，厉星星.对新形势下毕业设计管理工作的思考与实践[J].电气电子教学学报，2003(6):107-109. [2] 夏鲁惠.高等学校毕业设计(论文)教学情况调研报告[J].高等理科教育,2004(1):46-52. [3] Heider, E.R.& D.C.Oliver. The structure of color space in naming and memory of two languages [J]. Foreign Language Teaching and Research, 1999, (3): 62 67. 2．专著类
建设部文献中英文对照
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刀具术语中英文对照大全(3)
刀具术语中英文对照大全（3） 本文选自：主题名品网 指甲抠（Mark Side）：这是一个专门的刀具术语，刀片上有一个小突出物，通过这个突出物，可以将刀片从刀柄中抠出来。 粗面制作（Matte Finish）：刀片或者刀柄表面是磨砂或者起绒的，而不是完全的镜面。 米卡塔（Micarta）：最常见的是一种亚麻布，经过树脂的浸泡，形成一种质地轻盈并且坚固耐用的刀柄材料，它的表面没有特别清晰的纹理，摸起来非常的顺滑，因为其非常的柔软，处置不当的话会将其刮坏。 镜面加工（Mirror Finish）：通过接连不断的细致打磨和一系列的抛光工序，可以使得打磨面非常的光滑明亮，反光度非常的高。 指沟（Nail Mark/Nail Nick）：这是在口袋刀上的一个沟状设计，，可以将大拇指指甲插入后与食指合力将刀片夹住开启，是一种比较早期的开启机制。 镍（Nickel）：是参入到不锈钢制作中的一种合金，可以增加钢材的可塑性，同时，也可以增加钢材的抗腐蚀性。 镍黄铜（Nickel Silve）：是一种铜合金，一般含有10-45%的锌和5-30%的镍，通常用来制作刀具的衬垫。 非铁（Nonferrous）：一种不含任何铁的金属，比如说铝和钛。 正面（Obverse）：刀具的正视图。 反面（Pile Side）：是指一个刀具的反面，和上述的正视图是相反的那一面。 柄角（Pinky Shelf）：刀柄末端那个突出的角，是放小拇指的位置，刀柄的这个部位是为了提供一个杠杆支点，可以更好的掌握刀具。 平刃（Plain Edge）：是一个平缓的刀锋，刀刃上没有任何的锯齿或者其他齿状构造。 口袋夹（Pocket Clip）：一个夹子，可以将刀具固定在口袋的上部位置，方便取出。 刀尖（Point）：是刀刃和刀背的交汇处，即最尖锐的那部分。 粉末涂层（Powder Coating）：将干燥的粉末涂料涂在金属表面，然后将金属置于炉子里面，高温将粉末涂料融化，附于刀片的表面，可以增加刀片的抗腐蚀性。根据各种不同的需要，可以选择不同颜色的粉末图层。这种制作工艺是于1967年，产生于澳大利亚。 倒“S”刀（Reverse "S" Blade）：刀片的形状是一个倒的“S”，刀尖是向内弯曲的，靠下的刀腹和刀尖是一样的弯曲方向。 刀颈（Ricasso）：护手前或者刀刃开锋的初始部分，没有开锋的刀片。 洛克硬度测试（Rockwell Hardness Test）：是一种计量钢材硬度的标准测试。在特定的压力下，用金刚石抵住已完成的刀片，通过测量刺入的深度来判别钢材的硬度。硬度超过60RHC,.刀刃的开锋是比较难，然而低于56HRC的话，刀刃的锋利保持度却不高。 滑锁（Rolling Lock）：是刀具上的一个锁，利用轴承滑动的方法，滑向锁定的位置。 铁锈（Rust）：铁制品受到腐蚀，水合氧化物和铁发生反应，生成了氧化铁等物质，外观相应地发生了一些变化。 马刀（Sabre）：马刀的边缘非常的厚，可以胜任很多砍削任务和极端的环境下作业，刀背开始于刀刃的中部位置 磨光（Brushed Finish或Satin Finish）：是一种有别于镜面加工的打磨方式，通常是用一定规格的砂纸，对金属进行打磨，但是没有非常彻底的打磨，金属还保留原有的那种金属度。 斯克林肖（Scrimshaw）：是指在刀柄上雕刻装饰性图文的技艺。
中英文参考文献格式
中英文参考文献格式! (細節也很重要啊。。）来源：李菲玥的日志 规范的参考文献格式 一、参考文献的类型 参考文献（即引文出处）的类型以单字母方式标识，具体如下： M——专著C——论文集N——报纸文章J——期刊文章 D——学位论文R——报告S——标准P——专利 A——文章 对于不属于上述的文献类型，采用字母“Z”标识。 常用的电子文献及载体类型标识： ［ＤＢ/OL］——联机网上数据(database online) ［DB/MT］——磁带数据库(database on magnetic tape) ［Ｍ/CD］——光盘图书(monograph on CD ROM) ［ＣＰ／DK］——磁盘软件(computer program on disk) ［Ｊ／ＯＬ］——网上期刊(serial online) ［ＥＢ/OL］——网上电子公告(electronic bulletin board online) 对于英文参考文献，还应注意以下两点： ①作者姓名采用“姓在前名在后”原则，具体格式是：姓，名字的首字母. 如：Malcolm R ichard Cowley 应为：Cowley, M.R.，如果有两位作者，第一位作者方式不变，&之后第二位作者名字的首字母放在前面，姓放在后面，如：Frank Norris 与Irving Gordon应为：Norri s, F. & I.Gordon.； ②书名、报刊名使用斜体字，如：Mastering English Literature，English Weekly。二、参考文献的格式及举例 1．期刊类 【格式】[序号]作者.篇名[J].刊名，出版年份，卷号（期号）：起止页码. 【举例】 [1] 周融，任志国，杨尚雷，厉星星.对新形势下毕业设计管理工作的思考与实践[J].电气电子教学学报，2003(6)：107-109.
医学文献中英文对照
动脉粥样硬化所导致的心脑血管疾病是目前发病率和死亡率较高的疾病之一。在动脉粥样硬化的形成过程中, 内皮细胞病变是其中极其重要的因素，最显著的变化是动脉内皮功能紊乱, 血管内皮细胞的损伤和功能改变是动脉粥样硬化发生的起始阶段。 Cardiovascular and cerebrovascular disease caused by atherosclerosis is one of diseases with higher mortality and morbidity at present . In the formation of atherosclerosis, the endothelial cell lesion is one of the most important factors, in which, the most significant change is endothelial dysfunction. In addition, the injuries and the changes of vascular endothelial cells are the initial factors of atherosclerosis. 许多因素会导致血管内皮细胞受损, 主要包括脂多糖(Lipopolysaccharides , LPS)、炎症介质、氧自由基等。其中脂多糖因其广泛的生物学作用, 越来越引起研究者的关注。LPS 是一种炎症刺激物, 是革兰阴性杆菌细胞壁的主要组成成分，其通过刺激血管内皮细胞，引起其相关细胞因子和炎性因子的表达紊乱，尤其是Ca2+ 和活性氧簇(Reactive Oxygen Species , ROS的合成和释放发生改变诱导细胞氧化应激内环境紊乱。大量研究表明, LPS 直接参与动脉粥样硬化的形成过程, 特别是动脉粥样硬化血管炎症的初始阶段, LPS可通过直接作用或间接影响的方式激活并损伤内皮细胞，从而引 起血管内皮细胞形态与功能的改变。 Many factors induce vascular endothelial cell damage, including lipopolysaccharides (LPS), inflammatory mediators and oxygen free
机床术语中英文对照表.
常用机床术语中英文对照 机床中英文对照表 （您可以使用CTRL+F来查找） （1）：按英文字母排序 3-Jaws indexing spacers 三爪、分割工具头 A.T.C.system 加工中心机刀库 Aluminum continuous melting & holding 连续溶解保温炉furnaces Balancing equipment 平衡设备 Bayonet 卡口 Bearing fittings 轴承配件 Bearing processing equipment 轴承加工机 Bearings 轴承 Belt drive 带传动 Bending machines 弯曲机 Blades ????刀片 Blades,saw 锯片 Bolts,screws & nuts 螺栓,螺帽及螺丝 Boring heads 搪孔头 Boring machines 镗床 Cable making tools 造线机 Casting,aluminium 铸铝 Casting,copper 铸铜 Casting,gray iron 铸灰口铁 Casting,malleable iron 可锻铸铁 Casting,other 其他铸造 Casting,steel 铸钢
Chain drive 链传动 Chain making tools 造链机 Chamfer machines 倒角机 Chucks 夹盘 Clamping/holding systems 夹具/支持系统 CNC bending presses 电脑数控弯折机 CNC boring machines 电脑数控镗床 CNC drilling machines 电脑数控钻床 CNC EDM wire-cutting machines 电脑数控电火花线切削机CNC electric discharge machines 电脑数控电火花机 CNC engraving machines 电脑数控雕刻机 CNC grinding machines 电脑数控磨床 CNC lathes 电脑数控车床 CNC machine tool fittings 电脑数控机床配件 CNC milling machines 电脑数控铣床 CNC shearing machines 电脑数控剪切机 CNC toolings CNC刀杆 CNC wire-cutting machines 电脑数控线切削机Conveying chains 输送链 Coolers 冷却机 Coupling 联轴器 Crimping tools 卷边工具 Cutters 刀具 Cutting-off machines 切断机 Diamond cutters 钻石刀具 Dicing saws 晶圆切割机 Die casting dies 压铸冲模 Die casting machines 压铸机 Dies-progressive 连续冲模 Disposable toolholder bits 舍弃式刀头
英文引用及参考文献格式要求
英文引用及参考文献格式要求 一、参考文献的类型 参考文献（即引文出处）的类型以单字母方式标识，具体如下： M——专著C——论文集N——报纸文章 J——期刊文章D——学位论文R——报告 对于不属于上述的文献类型，采用字母“Z”标识。 对于英文参考文献，还应注意以下两点： ①作者姓名采用“姓在前名在后”原则，具体格式是：姓，名字的首字母.如：MalcolmRichardCowley应为：Cowley,M.R.，如果有两位作者，第一位作者方式不变，&之后第二位作者名字的首字母放在前面，姓放在后面，如：FrankNorris与IrvingGordon应为：Norris,F.&I.Gordon.； ②书名、报刊名使用斜体字，如：MasteringEnglishLiterature，EnglishWeekly。 二、参考文献的格式及举例 1.期刊类 【格式】[序号]作者.篇名[J].刊名，出版年份，卷号（期号）：起止页码. 【举例】 [1]王海粟.浅议会计信息披露模式[J].财政研究，2004,21(1)：56-58. [2]夏鲁惠.高等学校毕业论文教学情况调研报告[J].高等理科教育，2004(1):46-52. [3]Heider,E.R.&D.C.Oliver.Thestructureofcolorspaceinnamingandmemo ryoftwolanguages[J].ForeignLanguageTeachingandResearch,1999,(3):62–6 7. 2.专著类 【格式】[序号]作者.书名[M].出版地：出版社，出版年份：起止页码. 【举例】[4]葛家澍，林志军.现代西方财务会计理论[M].厦门：厦门大学出版社，2001：42. [5]Gill,R.MasteringEnglishLiterature[M].London:Macmillan,1985:42-45. 3.报纸类 【格式】[序号]作者.篇名[N].报纸名，出版日期（版次）. 【举例】 [6]李大伦.经济全球化的重要性[N].光明日报，1998-12-27(3). [7]French,W.BetweenSilences:AVoicefromChina[N].AtlanticWeekly,198 715(33). 4.论文集 【格式】[序号]作者.篇名[C].出版地：出版者，出版年份：起始页码. 【举例】 [8]伍蠡甫.西方文论选[C].上海：上海译文出版社，1979：12-17. [9]Spivak,G.“CantheSubalternSpeak?”[A].InC.Nelson&L.Grossberg(e ds.).VictoryinLimbo:Imigism[C].Urbana:UniversityofIllinoisPress,1988, pp.271-313.
平面设计中英文对照外文翻译文献
(文档含英文原文和中文翻译) 中英文翻译 平面设计 任何时期平面设计可以参照一些艺术和专业学科侧重于视觉传达和介绍。采用多种方式相结合，创造和符号，图像和语句创建一个代表性的想法和信息。平面设计师可以使用印刷，视觉艺术和排版技术产生的最终结果。平面设计常常提到的进程，其中沟通是创造和产品设计。 共同使用的平面设计包括杂志，广告，产品包装和网页设计。例如，可能包括产品包装的标志或其他艺术作品，举办文字和纯粹的设计元素，如形状和颜色统一件。组成的一个最重要的特点，尤其是平面设计在使用前现有材料或不同的元素。 平面设计涵盖了人类历史上诸多领域，在此漫长的历史和在相对最近爆炸视觉传达中的第20和21世纪，人们有时是模糊的区别和重叠的广告艺术，平面设计和美术。毕竟，他们有着许多相同的内容，理论，原则，做法和语言，有时同样的客人或客户。广告艺术的最终目标是出售的商品和服务。在平面
设计，“其实质是使以信息，形成以思想，言论和感觉的经验”。 在唐朝（ 618-906 ）之间的第4和第7世纪的木块被切断打印纺织品和后重现佛典。阿藏印在868是已知最早的印刷书籍。 在19世纪后期欧洲，尤其是在英国，平面设计开始以独立的运动从美术中分离出来。蒙德里安称为父亲的图形设计。他是一个很好的艺术家，但是他在现代广告中利用现代电网系统在广告、印刷和网络布局网格。 于1849年，在大不列颠亨利科尔成为的主要力量之一在设计教育界，该国政府通告设计在杂志设计和制造的重要性。他组织了大型的展览作为庆祝现代工业技术和维多利亚式的设计。 从1892年至1896年威廉?莫里斯凯尔姆斯科特出版社出版的书籍的一些最重要的平面设计产品和工艺美术运动，并提出了一个非常赚钱的商机就是出版伟大文本论的图书并以高价出售给富人。莫里斯证明了市场的存在使平面设计在他们自己拥有的权利，并帮助开拓者从生产和美术分离设计。这历史相对论是，然而，重要的，因为它为第一次重大的反应对于十九世纪的陈旧的平面设计。莫里斯的工作，以及与其他私营新闻运动，直接影响新艺术风格和间接负责20世纪初非专业性平面设计的事态发展。 谁创造了最初的“平面设计”似乎存在争议。这被归因于英国的设计师和大学教授Richard Guyatt，但另一消息来源于20世纪初美国图书设计师William Addison Dwiggins。 伦敦地铁的标志设计是爱德华约翰斯顿于1916年设计的一个经典的现代而且使用了系统字体设计。 在20世纪20年代，苏联的建构主义应用于“智能生产”在不同领域的生产。个性化的运动艺术在俄罗斯大革命是没有价值的，从而走向以创造物体的功利为目的。他们设计的建筑、剧院集、海报、面料、服装、家具、徽标、菜单等。 Jan Tschichold 在他的1928年书中编纂了新的现代印刷原则，他后来否认他在这本书的法西斯主义哲学主张，但它仍然是非常有影响力。 Tschichold ，包豪斯印刷专家如赫伯特拜耳和拉斯洛莫霍伊一纳吉，和El Lissitzky 是平面设计之父都被我们今天所知。 他们首创的生产技术和文体设备，主要用于整个二十世纪。随后的几年看到平面设计在现代风格获得广泛的接受和应用。第二次世界大战结束后，美国经济的建立更需要平面设计，主要是广告和包装等。移居国外的德国包豪斯设计学院于1937年到芝加哥带来了“大规模生产”极简到美国;引发野火的“现代”建筑和设计。值得注意的名称世纪中叶现代设计包括阿德里安Frutiger ，设计师和Frutiger字体大学;保兰德，从20世纪30年代后期，直到他去世于1996年，采取的原则和适用包豪斯他们受欢迎的广告和标志设计，帮助创造一个独特的办法，美国的欧洲简约而成为一个主要的先驱。平面设计称为企业形象;约瑟夫米勒，罗克曼，设计的海报严重尚未获取1950年代和1960年代时代典型。 从道路标志到技术图表，从备忘录到参考手册，增强了平面设计的知识转让。可读性增强了文字的视觉效果。 设计还可以通过理念或有效的视觉传播帮助销售产品。将它应用到产品和公司识别系统的要素像标志、颜色和文字。连同这些被定义为品牌。品牌已日益成为重要的提供的服务范围，许多平面设计师，企业形象和条件往往是同时交替使用。
数控机床刀具设计论文中英文资料外文翻译文献综述
数控机床刀具设计 中英文资料 英语原文： Design Of Tool Machine Prop Research significance The original knife machine control procedures are designed individually, not used tool management system, features a single comparison, the knife only has to find the tool knife, knife positioning the shortest path, axis tool change, but does not support large-scale tool. Automatic knife in the knife election, in the computer memory knife-election on the basis of using the Siemens 840 D features, and the election procedures knife more concise, and complete the space Daotao View. ATC use the knife rapid completion of STEP-7 programming, and have been tested in practice. In the positioning of the knife, PLC controlled modular design method, which future production of similar machines will be very beneficial, it is easy to use its other machine. Automatic tool change systems will be faster growth, reduced tool change time, increase the positioning accuracy tool is an important means to help NC technology development. Tool and inventory components of modern production is an important link in the management, especially for large workshop D features, and the election procedures knife more concise, and complete the space Daotao View. ATC use the knife rapid completion of STEP-7 programming, and have been tested in practice. In the positioning of the knife, PLC controlled modular design method, which future production of similar machines will be very beneficial, it is easy to use its oth management. The traditional way of account management, and low efficiency, high error rate, and not sharing information and data, tools and the use of state can not track the life cycle, are unable to meet the current information management needs. With actual production, we have to establish a workshop tool for the three-dimensional tool storage system to meet the knife workshop with auxiliary storage and management needs. The system uses optimization technology, a large number of computer storage inventory information, timely, accurate, and comprehensive tool to reflect the inventory situation. The entire system uses a graphical interface, man-machine dialogue tips from the Chinese menu, select various functions can be realized and the importation of all kinds of information. Management system using online help function. Through the workshop management, network management and sharing of information. Have automated inventory management, warehousing management tool, a tool for the management and statistical functions. 1.System components and control structure The entire system, including the structure and electrical machinery control systems. 1.1.1Mechanical structure and working principle Tool from the stent, drive, drive system, Turret, shielding, control system, and electrical components. Support from the column, beam, the upper and lower guide Central track, and track support component.
统计学中英文对照外文翻译文献
中英文对照翻译 (文档含英文原文和中文翻译) Policies for Development of Iron and Steel Industry The iron and steel industry is an important basic industry of the national economy, a supporting industry for realizing the industrialization and an intensive industry in technologies, capital, resources and energy, and its development requires a comprehensive balancing of all kinds of external conditions. China is a big developing country with a comparatively big demand of iron and steel in the economic development for a long time to go. China's production capacity of iron and steel has ranked the first place in the world for many years. However, there is a large gap in terms of the technological level and material consumption of the iron and steel industry compared with the international advanced level, so the focus of development for the future shall be put on technical upgrading and structural adjustment. In order to enhance the whole technical level of the iron and steel industry, promote the structural adjustment, improve the industrial layout, develop a recycling economy, lower the consumption of materials and energy, pay attention to the environmental protection, raise the comprehensive competitive capacity of enterprises, realize the industrial upgrading, and develop the iron and steel industry into an industry with