Address arrangement, like our daily home address, is used to distinguish identities.
Your network must be able to distinguish this address from other addresses. In the network, a large number of data packets will be sent from one network node to another, just like a post office. At the same time, it is necessary to ensure that the data packet will be sent to the destination correctly, which must be determined by the address of this network card.
Question 2: What does a work node mean? Five points.
Question 3: What does the time node mean? Time node is a very abstract and widely used concept. In layman's terms, it is a point or a segment in the big environment, just like a platform in a bus line. For example, it is reflected in the time limit of the project plan or work plan. Taking the construction period as an example, the time node can represent a certain stage or milestone of the project, and the work before this stage or milestone needs to be completed before a certain time, which is often mentioned in the project. The same is true of other industries. For example, the development of a software needs to be completed at a certain time, the debugging needs to be completed at a certain time, and the sales promotion needs to be completed at a certain time. These are all time nodes.
Question 4: What is a node in a circuit? The connection point between any two circuit elements is called a node. When the potentials are the same, they can be considered as the same node.
Circuit: A conductive circuit composed of metal wires and electrical and electronic components is called a circuit. When a power supply is added to the input of the circuit, a potential difference is generated at the input, and the circuit can work. Some phenomena can be seen intuitively, such as voltmeter or ammeter, deflection of light bulb, etc. Some people may need measuring instruments to know whether they are working properly. According to the nature of current flow, it is generally divided into two types. The circuit through which direct current passes is called "DC circuit" and the circuit through which alternating current passes is called "AC circuit".
Question 5: What is the node area? Node is a very abstract and widely used concept. It is a point or a section in a big environment, just like a platform in a bus line.
First of all, in the XML language
A node is the smallest unit of an effective and complete structure in an XML file. Nodes containing tag groups and necessary attributes, attribute values and contents can form an element. Identifier of the node.
Question 6: What is node numerical control technology, referred to as "numerical control"? English: numerical control (NC). It refers to the technology of using digital instructions composed of numbers, characters and symbols to realize the action control of one or more mechanical devices. Usually control mechanical quantities such as position, angle and speed, as well as switching quantities related to the flow direction of mechanical energy. The appearance of numerical control depends on the appearance of data carrier and binary data operation. 1908, perforated metal foil interchangeable data carrier came out; At the end of 19, a control system with auxiliary functions was invented with paper as the data carrier. During the period of 1938, Shannon carried out rapid data calculation and transmission at MIT, which laid the foundation for modern computers, including computer numerical control systems. Numerical control technology is closely combined with machine tool control and developed. 1952, the first CNC machine tool came out, which became an epoch-making event in the history of the world machinery industry and promoted the development of automation.
Now, numerical control technology is also called computer numerical control technology. At present, it is a technology to realize digital program control by computer. This technology uses a computer to execute the control function of the equipment according to the pre-stored control program. Because the numerical control device composed of hardware logic circuit is replaced by computer, the storage, processing, operation, logical judgment and other control functions of input data can be realized by computer software.
The application of numerical control technology has not only brought revolutionary changes to the traditional manufacturing industry, making the manufacturing industry a symbol of industrialization, but also played an increasingly important role in the development of some important industries (IT, automobile, light industry, medical care, etc.). ) With the continuous development of numerical control technology and the continuous expansion of application fields, the digitalization of equipment required by these industries has become a major trend of modern development. Judging from the development trend of numerical control technology and its equipment in the world, its main research hotspots are as follows.
1. New trend of high-speed and high-precision machining technology and equipment
Efficiency and quality are the main components of advanced manufacturing technology. High-speed and high-precision machining technology can greatly improve efficiency, improve product quality and grade, shorten production cycle and improve market competitiveness. Therefore, Japan Advanced Technology Research Association listed it as one of the five major technologies of modern manufacturing, and CIRP identified it as one of the central research fields in 2 1 century.
In the field of automobile industry, the production cycle of 300,000 cars per year is 40 seconds, and multi-variety processing is one of the key problems that automobile equipment must solve. In the aerospace field, most of the machined parts are thin-walled ribs with poor stiffness, and the materials are aluminum or aluminum alloy. Only under the condition of high cutting speed and small cutting force can these ribs and walls be machined. Recently, large-scale components such as wings and fuselage are manufactured by hollowing out large-scale integral aluminum alloy blanks, instead of assembling multiple components through numerous rivets and screws, so that the strength, stiffness and reliability of the components are improved. All these require high speed, high precision and high flexibility for processing equipment.
According to EMO200 1, the feed speed of high-speed machining center can reach 80m/min or even higher, and the idling speed can reach about 100m/min. At present, many automobile factories in the world, including Shanghai General Motors Corporation in China, have partially replaced modular machine tools with production lines composed of high-speed machining centers. The HyperMach machine tool of Cincinnati, USA has a maximum feed speed of 60m/min, a fast speed of 100m/min, an acceleration of 2g and a spindle speed of 60000r/min. It only takes 30 minutes to process a thin-walled aircraft part, while it takes 3 hours to process the same part on a common high-speed milling machine and 8 hours on a common milling machine. The spindle speed and acceleration of the double-spindle lathe produced by German DMG company reach 12* respectively! 000 rpm and 1 g.
In terms of machining accuracy, in recent 10 years, the machining accuracy of ordinary CNC machine tools has increased from 10μm to 5μm, and the precision machining center has increased from 3 ~ 5μ m to 1 ~ 1.5μ m, and the ultra-precision machining accuracy has begun to enter the nanometer level (0.0 1μm).
In terms of reliability, the MTBF value of foreign numerical control devices has reached more than 6 000h, and the MTBF value of servo system has reached more than 30000h, showing very high reliability.
In order to realize high-speed and high-precision machining, motorized spindle, linear motor and other supporting functional components have been rapidly developed and applied. & gt
Question: What does DOM node mean? In the form of a tree,
Locate each node.
In this way, you can find the parent node, child node and so on according to a target node.
For example, there is a div on the web page, and there is a p in the div.
You want to modify the font size of p and the background color of div.
Then first find the P node and modify the css.
Then find the parent node through the p node and find the div.
Then modify the css of div.
Question 8: What is a text node? Are you talking about xml? A text node is a text that is not enclosed: C in C.
Question 9: What is node management? This method was proposed by Clarke and Wright in 1964 to solve the vehicle routing problem. The idea is to sort from the largest to the smallest according to the saving value (the difference between the shorter route and the original route), and under the restriction of vehicle capacity, the corresponding two customer points are discharged into the route in turn until all customers are discharged into the route. The essential requirement of this method is to save routing cost.
Solomn applied this method to solve the vehicle routing problem with time window constraints in 1983. The key point is that when two customer points with large savings are put into the route, not only the vehicle capacity limit, but also the time window limit should be considered, that is, the upper bound of the time window should be given priority and its time feasibility should be tested. The advantage of this method is to improve the utilization rate of vehicles. The calculation formula and significance of saving between two nodes are as follows:
s(i，j)=d(i，0)+d(0，j)？ d(i，j)
Where d(i, 0) represents the distance from customer I to the station and d(i, j) represents the distance from customer I to J. When calculating the saving value s(i, j) between two nodes I and J, the sum of all round-trip paths in the original path should be calculated first, and then compared with the sum of the total paths with shorter loops. The original paths of two nodes are short-circuited, as shown in the following figure:
Main steps of saving method
1. In the case that one truck is responsible for one customer and several trucks are responsible for several customers, calculate the route cost separately and calculate its separate cost.
2. After the routes are merged and the total cost is calculated, the routes will be exchanged.
3. Through the above two steps, do the operation again, count all the combination possibilities and results, and see what the route with the lowest cost is.
Question 10: What is a network node? In fact, it refers to any equipment with a unique network address, such as websites, network fax machines, network printers, file servers, etc. In addition, because each network card will be assigned an address by the manufacturer when it leaves the factory, it is impossible for users to change this address.
Address arrangement, like our daily home address, is used to distinguish identities.
Your network must be able to distinguish this address from other addresses. In the network, a large number of data packets will be sent from one network node to another, just like a post office. At the same time, it is necessary to ensure that the data packet will be sent to the destination correctly, which must be determined by the address of this network card.