4 thoughts on “Have you seen three dozen and one figure?”
Chris
In the information age, everyone’s work and life have a deep or shallow relationship with the network and computers. The proportion of personal information in the computer is increasing. In addition to the convenience of the computer network, we We should pay attention to the security of computer, especially in the face of complicated computer vulnerabilities and diverse computer security issues at this stage. We should also talk about the security maintenance of the computer in an important position. In computer security, the most important thing is the security of the database.
"" magazine is a national journal directly facing the high -end and high -end computer education business issued by the Ministry of Education and sponsored by Tsinghua University. It was designated as special recommendations for special recommendations It is currently the only journal in the domestic computer education community.
The personal information was leaked, property was stolen, the disappearance or stolen of various accounts, etc., the vulnerabilities on these data will cause serious problems. Therefore, the security exploration of the database is Next important topic.
. The basic understanding of the safety of database and database
It to study the security of the database, we must understand what database is essentially. Can be discussed correctly. The so -called database is simply the collection of data stored in the computer. The database is a huge warehouse that stores data. The main function of this warehouse is to save and properly manage data through computers, so that we can make full use of information resources.
The origin of the database is not very early, but the rapid information development speed proves its importance in information technology. As the requirements of data management continue to improve, the data management system that adapts to the management sharing of data in the new era has begun to appear, namely DBMS, where the data model is the core and foundation of the database system.
The safety of the database is to ensure the integrity of the database. Of course, it will be applied to many protection technologies and means, so as to prevent hackers or other attackers from stealing and destruction of data. This is to be Ensure the security, availability, confidentiality, consistency, and resistance of data. In this way, we can further ensure the integrity of the database and truly maintain the safety of the database.
. The importance of database security
First, the database plays an important position in the information system, which has an important role in our daily work and life. Organization, storage and management and protection make our production and life more orderly and convenient.
The status of security based on database -based is conceivable. First of all, the security of computer databases has important significance to ensuring information and data security, especially those important information, which plays an important role in the production and life of individuals and even a group. Second, the security of the database is also that the computer operating system can be safe. Important conditions and prerequisites for running. If there is a loophole in the database and is attacked or destroyed, it will cause significant harm to some programs and even the entire system. The normal order maintenance of normal operation to people's production and life is inseparable from the security maintenance of the database. Therefore, the discovery of database security issues and the study of the solution to these problems are also necessary.
. The security threat and problems of the database
(1) Reject service attack.
In this attack type, users' access to the network database will be rejected. There are many consequences caused by such attacks, but it is usually blackmail and extorted, which will have a adverse effect on the user's property security. Essence
(2) Destruction of malicious attacks on databases.
Mreatless malicious attacks from the Internet are often targeted at data. The attacker stole user data, causing the integrity of the database to be destroyed; in addition, the attacker will also perform the data on the data Malicious guidance, this has damaged the authenticity of the database. The destruction of these attackers is also a huge threat of database safety.
(3) backup data exposure.
The backup data was originally in maintenance of data security, but due to insufficient encryption or other security loopholes, backup data often encountered stolen or directed. Harm.
1. Conditions that CNC machine tool repair technicians should have
First of all, strong sense of responsibility and good professional ethics; second, to ensure broad knowledge, understand computer technology, Internet technology, simulation figures Circuit technology, automatic control motor drag technology, modern CNC machine tool detection technology, and mechanical processing technology technology should also have a solid level of foreign language application level; again, professional technical training should be conducted before formal entering the job. Master the relevant CNC driver technology, PLC technology principles and CNC programming technology and programming language; finally, you must master various testing equipment and instruments and various tools.
. Do a good job of maintenance preparation
The on -site maintenance is a failure to diagnose the failure of the CNC machine tool (mainly the CNC), find out the fault, and use the corresponding normal Replacement of spare parts to restore the machine tool to run normally. The key to this process is diagnosis, that is, to detect the system or peripheral lines, determine whether there is any failure, and point out the exact position of the fault positioning. From the entire machine to the plug -in board, or even the components in some occasions. This is the main part of the entire maintenance work.
3. On -site failure diagnosis
First, preliminary diagnosis. When the fault on -site information is relatively comprehensive, you can use the data analysis to determine the location of the fault, or adopt the interface signal method to combine the fault phenomenon to make a preliminary diagnosis of the fault, and then check the specific characteristics of the fault. Preliminary diagnosis. During the actual failure diagnosis, sometimes only one method can be used to diagnose faults, and sometimes a comprehensive application of multiple detection methods is used to diagnose the fault. Diagnosis and identification of various fault points mainly depends on the operating characteristics and structural fault depth of the faulty device; secondly, the alarm treatment. It is mainly divided into two types, one is system failure alarm treatment. After the failure of the CNC machine tool system, the corresponding alarm signal will appear on the display or the operating panel. Then the maintenance personnel can handle and exclude the fault in combination , Maintenance personnel can perform targeted operation in combination with different signals. The second type is the alarm and operation information processing of CNC machine tools. During the production process of CNC machine tools, PLC control levels are displayed to fail or operate information that can reflect the electrical control of the machine tool interface with specific signs, and to obtain a more detailed fault judgment instruction through specific keys. On the one hand, the alarm manual can be used for processing, and on the other hand, it can be combined with the PLC program to check the corresponding signals and finally diagnose the fault. Finally, the fault treatment of the alarm is mistaken. When the PLC of the system cannot run, the system has been stopped or the system is not alarm, but when the work is abnormal, it is necessary to use the theoretical foundation of the system before and after the failure of the fault to analyze the correct theoretical basis and make correct judgments.
IBM high -performance computer system undertakes the main weather and climate business scientific research model operation of the China Meteorological Bureau. Since the installation of the system at the end of 2004, the operation has been relatively stable. Throughout the system, the data exchange is implemented through the IBM HPS (High Switch) network, providing communication with users' parallel operations through the Switch network.
1 Basic situation of failure
On September 21, 2006, the system performance of scientific research partitions decreases, and the operation speed of user operations is relatively slow. 1] The communication status of the network appears abnormal in large areas, which affects the normal operation of the GPFS (General Parallel File System) [2] data file system and operation management software. After users cannot use scientific research partitions; after Switch network communication is normal, some files in the GPFS file system cannot be accessed normally.
. After ensuring that the business could run stably, because the user was unable to use the scientific research partition at that time, it first applied for a shutdown to maintain the scientific research partition, and then analyzed and resolved the fault. The processing process was as follows.
The paper was published in the journal "", and the magazine was hosted by the head of the Ministry of Information Industry and the 30th Research Institute of China Electronic Technology Group. 16th, published on the 10th of each month, and publicly released at home and abroad. The magazine was founded in 1967, a professional computer media with a long time and great influence in China, and the 2004 version of the Chinese core journal.
(1) Analyze HPS network communication data, and find that the internal communication of the chip on the two motherboards of the F45 1 S11 and F46 1 S07 is abnormal, and decided to replace these two motherboards; The reason is that there is only one motherboard available, and only the motherboard of the F46 1 S07 Switch is replaced.
(2) After the re -power is added, there are still a large number of HPS networks that cannot be communicated, resulting in GPFS unable to work stably, and users cannot submit their homework normally.
2 The cause of the failure
2. The control signal transmission process
It from Figure 1, the IBM high -performance computer system controls the terminal HMC ( Hardware Console) controls the hardware of the host and Switch, and manages HPS through the SNM (Switch Network Manager) software on HMC, and starts the FNMD (Network Manager Daemon) process on HMC to achieve the allocation, initialization, surveillance, and control of the HPS network , Restore, analysis and diagnosis. This function has nothing to do with whether the node is installed, because these instructions are directly launched by HMC, and the control instructions are transmitted through the power supply. As long as the power supply is normal, it will respond to execution. acquired.
The layered class teaching is to divide these students into several levels according to their existing knowledge foundation and their learning ability and interest in disciplines, set up several levels of class, and combine the principles of "independent selection, teacher -student cooperation" principle of students. , Make students at different levels of teaching activities that are suitable for their own levels to carry out teaching activities. The same subject carried out teaching activities at the same time, and students went to class at the corresponding level, and the original administrative class remained unchanged. It is a learning mode of non -fixed class and liquidity. As a result, the learning difficulty of "learning difficulties" is reduced, and the needs of "learning excellence" to expand knowledge. Compared with the traditional teaching model, the "layered class" teaching can give full play to the advantages of different students, mobilize the initiative of students to learn, improve the comprehensive quality of students, and promote the personalized development of students.
. The concept and theoretical basis of layered class teaching is based on
1. Individual differences and teaching theory according to their aptitude. The individual differences of students exist objectively. Only according to the characteristics of the students and the characteristics of the personality, and adopt the compatible education and teaching measures, can we achieve the best education and teaching effects.
2. The "master learning theory" proposed by Bloom. The masterpiece of learning theory proposed by Bloom emphasized that each student has the ability to understand and master any teaching content. As long as there are suitable learning conditions, most students will change in terms of learning ability and learning rate. It is very similar. The layered teaching is the effective means of realizing his theoretical concept of "deducting differences from differences to destroy differences."
3. Weiguitzki's theory of "recent development zone". The theory of "recent Development Zone" believes that there are two levels of each student: one is the existing level, and the other is the potential level. They are called the "recent development zone" and "best teaching zone". The process of transforming the existing level from potential level to new existing levels and continuously creates a new recent development zone.
. The necessity of layered class teaching
This 1. The inevitable need for the reform of the examination enrollment system. With the popularization of high school education
The publicization of education and university education, under the new examination enrollment system, high school education should not
It is necessary to turn to "everyone's talent", and should be
The concentration from "walking" to "common and individuality". The personalization of education is based on respect for the differences in students. It requires that students are divided into different categories and levels according to the different levels of personal learning, methods and abilities of students, and implementing classification and layered teaching. The true transformation of ideas occurs in the process of practice, so the practice of "class selection and class" is particularly important. Students at the same level design different teaching goals and exercises, and adopt different teaching processes to make the actual teaching process more targeted, improve the efficiency of teachers and students cooperation, and exchanges. Joy, get learning fun.
In the information age, everyone’s work and life have a deep or shallow relationship with the network and computers. The proportion of personal information in the computer is increasing. In addition to the convenience of the computer network, we We should pay attention to the security of computer, especially in the face of complicated computer vulnerabilities and diverse computer security issues at this stage. We should also talk about the security maintenance of the computer in an important position. In computer security, the most important thing is the security of the database.
"" magazine is a national journal directly facing the high -end and high -end computer education business issued by the Ministry of Education and sponsored by Tsinghua University. It was designated as special recommendations for special recommendations It is currently the only journal in the domestic computer education community.
The personal information was leaked, property was stolen, the disappearance or stolen of various accounts, etc., the vulnerabilities on these data will cause serious problems. Therefore, the security exploration of the database is Next important topic.
. The basic understanding of the safety of database and database
It to study the security of the database, we must understand what database is essentially. Can be discussed correctly. The so -called database is simply the collection of data stored in the computer. The database is a huge warehouse that stores data. The main function of this warehouse is to save and properly manage data through computers, so that we can make full use of information resources.
The origin of the database is not very early, but the rapid information development speed proves its importance in information technology. As the requirements of data management continue to improve, the data management system that adapts to the management sharing of data in the new era has begun to appear, namely DBMS, where the data model is the core and foundation of the database system.
The safety of the database is to ensure the integrity of the database. Of course, it will be applied to many protection technologies and means, so as to prevent hackers or other attackers from stealing and destruction of data. This is to be Ensure the security, availability, confidentiality, consistency, and resistance of data. In this way, we can further ensure the integrity of the database and truly maintain the safety of the database.
. The importance of database security
First, the database plays an important position in the information system, which has an important role in our daily work and life. Organization, storage and management and protection make our production and life more orderly and convenient.
The status of security based on database -based is conceivable. First of all, the security of computer databases has important significance to ensuring information and data security, especially those important information, which plays an important role in the production and life of individuals and even a group. Second, the security of the database is also that the computer operating system can be safe. Important conditions and prerequisites for running. If there is a loophole in the database and is attacked or destroyed, it will cause significant harm to some programs and even the entire system. The normal order maintenance of normal operation to people's production and life is inseparable from the security maintenance of the database. Therefore, the discovery of database security issues and the study of the solution to these problems are also necessary.
. The security threat and problems of the database
(1) Reject service attack.
In this attack type, users' access to the network database will be rejected. There are many consequences caused by such attacks, but it is usually blackmail and extorted, which will have a adverse effect on the user's property security. Essence
(2) Destruction of malicious attacks on databases.
Mreatless malicious attacks from the Internet are often targeted at data. The attacker stole user data, causing the integrity of the database to be destroyed; in addition, the attacker will also perform the data on the data Malicious guidance, this has damaged the authenticity of the database. The destruction of these attackers is also a huge threat of database safety.
(3) backup data exposure.
The backup data was originally in maintenance of data security, but due to insufficient encryption or other security loopholes, backup data often encountered stolen or directed. Harm.
1. Conditions that CNC machine tool repair technicians should have
First of all, strong sense of responsibility and good professional ethics; second, to ensure broad knowledge, understand computer technology, Internet technology, simulation figures Circuit technology, automatic control motor drag technology, modern CNC machine tool detection technology, and mechanical processing technology technology should also have a solid level of foreign language application level; again, professional technical training should be conducted before formal entering the job. Master the relevant CNC driver technology, PLC technology principles and CNC programming technology and programming language; finally, you must master various testing equipment and instruments and various tools.
. Do a good job of maintenance preparation
The on -site maintenance is a failure to diagnose the failure of the CNC machine tool (mainly the CNC), find out the fault, and use the corresponding normal Replacement of spare parts to restore the machine tool to run normally. The key to this process is diagnosis, that is, to detect the system or peripheral lines, determine whether there is any failure, and point out the exact position of the fault positioning. From the entire machine to the plug -in board, or even the components in some occasions. This is the main part of the entire maintenance work.
3. On -site failure diagnosis
First, preliminary diagnosis. When the fault on -site information is relatively comprehensive, you can use the data analysis to determine the location of the fault, or adopt the interface signal method to combine the fault phenomenon to make a preliminary diagnosis of the fault, and then check the specific characteristics of the fault. Preliminary diagnosis. During the actual failure diagnosis, sometimes only one method can be used to diagnose faults, and sometimes a comprehensive application of multiple detection methods is used to diagnose the fault. Diagnosis and identification of various fault points mainly depends on the operating characteristics and structural fault depth of the faulty device; secondly, the alarm treatment. It is mainly divided into two types, one is system failure alarm treatment. After the failure of the CNC machine tool system, the corresponding alarm signal will appear on the display or the operating panel. Then the maintenance personnel can handle and exclude the fault in combination , Maintenance personnel can perform targeted operation in combination with different signals. The second type is the alarm and operation information processing of CNC machine tools. During the production process of CNC machine tools, PLC control levels are displayed to fail or operate information that can reflect the electrical control of the machine tool interface with specific signs, and to obtain a more detailed fault judgment instruction through specific keys. On the one hand, the alarm manual can be used for processing, and on the other hand, it can be combined with the PLC program to check the corresponding signals and finally diagnose the fault. Finally, the fault treatment of the alarm is mistaken. When the PLC of the system cannot run, the system has been stopped or the system is not alarm, but when the work is abnormal, it is necessary to use the theoretical foundation of the system before and after the failure of the fault to analyze the correct theoretical basis and make correct judgments.
IBM high -performance computer system undertakes the main weather and climate business scientific research model operation of the China Meteorological Bureau. Since the installation of the system at the end of 2004, the operation has been relatively stable. Throughout the system, the data exchange is implemented through the IBM HPS (High Switch) network, providing communication with users' parallel operations through the Switch network.
1 Basic situation of failure
On September 21, 2006, the system performance of scientific research partitions decreases, and the operation speed of user operations is relatively slow. 1] The communication status of the network appears abnormal in large areas, which affects the normal operation of the GPFS (General Parallel File System) [2] data file system and operation management software. After users cannot use scientific research partitions; after Switch network communication is normal, some files in the GPFS file system cannot be accessed normally.
. After ensuring that the business could run stably, because the user was unable to use the scientific research partition at that time, it first applied for a shutdown to maintain the scientific research partition, and then analyzed and resolved the fault. The processing process was as follows.
The paper was published in the journal "", and the magazine was hosted by the head of the Ministry of Information Industry and the 30th Research Institute of China Electronic Technology Group. 16th, published on the 10th of each month, and publicly released at home and abroad. The magazine was founded in 1967, a professional computer media with a long time and great influence in China, and the 2004 version of the Chinese core journal.
(1) Analyze HPS network communication data, and find that the internal communication of the chip on the two motherboards of the F45 1 S11 and F46 1 S07 is abnormal, and decided to replace these two motherboards; The reason is that there is only one motherboard available, and only the motherboard of the F46 1 S07 Switch is replaced.
(2) After the re -power is added, there are still a large number of HPS networks that cannot be communicated, resulting in GPFS unable to work stably, and users cannot submit their homework normally.
2 The cause of the failure
2. The control signal transmission process
It from Figure 1, the IBM high -performance computer system controls the terminal HMC ( Hardware Console) controls the hardware of the host and Switch, and manages HPS through the SNM (Switch Network Manager) software on HMC, and starts the FNMD (Network Manager Daemon) process on HMC to achieve the allocation, initialization, surveillance, and control of the HPS network , Restore, analysis and diagnosis. This function has nothing to do with whether the node is installed, because these instructions are directly launched by HMC, and the control instructions are transmitted through the power supply. As long as the power supply is normal, it will respond to execution. acquired.
The layered class teaching is to divide these students into several levels according to their existing knowledge foundation and their learning ability and interest in disciplines, set up several levels of class, and combine the principles of "independent selection, teacher -student cooperation" principle of students. , Make students at different levels of teaching activities that are suitable for their own levels to carry out teaching activities. The same subject carried out teaching activities at the same time, and students went to class at the corresponding level, and the original administrative class remained unchanged. It is a learning mode of non -fixed class and liquidity. As a result, the learning difficulty of "learning difficulties" is reduced, and the needs of "learning excellence" to expand knowledge. Compared with the traditional teaching model, the "layered class" teaching can give full play to the advantages of different students, mobilize the initiative of students to learn, improve the comprehensive quality of students, and promote the personalized development of students.
. The concept and theoretical basis of layered class teaching is based on
1. Individual differences and teaching theory according to their aptitude. The individual differences of students exist objectively. Only according to the characteristics of the students and the characteristics of the personality, and adopt the compatible education and teaching measures, can we achieve the best education and teaching effects.
2. The "master learning theory" proposed by Bloom. The masterpiece of learning theory proposed by Bloom emphasized that each student has the ability to understand and master any teaching content. As long as there are suitable learning conditions, most students will change in terms of learning ability and learning rate. It is very similar. The layered teaching is the effective means of realizing his theoretical concept of "deducting differences from differences to destroy differences."
3. Weiguitzki's theory of "recent development zone". The theory of "recent Development Zone" believes that there are two levels of each student: one is the existing level, and the other is the potential level. They are called the "recent development zone" and "best teaching zone". The process of transforming the existing level from potential level to new existing levels and continuously creates a new recent development zone.
. The necessity of layered class teaching
This 1. The inevitable need for the reform of the examination enrollment system. With the popularization of high school education
The publicization of education and university education, under the new examination enrollment system, high school education should not
It is necessary to turn to "everyone's talent", and should be
The concentration from "walking" to "common and individuality". The personalization of education is based on respect for the differences in students. It requires that students are divided into different categories and levels according to the different levels of personal learning, methods and abilities of students, and implementing classification and layered teaching. The true transformation of ideas occurs in the process of practice, so the practice of "class selection and class" is particularly important. Students at the same level design different teaching goals and exercises, and adopt different teaching processes to make the actual teaching process more targeted, improve the efficiency of teachers and students cooperation, and exchanges. Joy, get learning fun.