decibels explained

Basic KnowledgeMeasure the sound intensity, the most familiar unit is the decibel (decibel, abbreviated to DB). This is a non-dimensional relative unit , the calculation formula is as follows:The numerator is the sound pressure of the measured value, and the denominator is the sound pressure of the reference value (20 kpa, the minimum sound pressure the human can hear). So the daily sound intensity is the number of decibels, the default is a very smal

Basic KnowledgeMeasure sound intensity. The most familiar unit is the decibel (decibel, abbreviated as db). This is a non-dimensional relative unit . The calculation formula is as follows:The numerator is a measured value of the sound pressure, the denominator is the value of the sound pressure (20 micro-Pa. The minimum sound pressure a human can hear).So the daily sound intensity is how many decibels. Is the default of a very small reference value.Wh

Hu bojun explained the reasons for invalid comments in CSS and Hu bojun explained the failure of css.In a webpage automatically generated by Dreamweaver, style sheets in the head are usually in the following format: An html annotation is automatically added at the beginning and end of the style sheet: When This is a low-level error that is easily overlooked. The reason is simple. The comments Syntax of CS

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Volatile in Java does not guarantee thread safety (example explained)Reprinted 2017-09-04 Think-007 I want to commentThe following small series to bring you a piece of Java in the volatile can not guarantee thread safety (the example explained). Small series feel very good, now share to everyone, also for everyone to make a reference. Follow the small part together to look at it today hit the code to see if

Java access is as common as classes and objects, and is ubiquitous in Java programs. Java access, depending on the permission range from large to small: public > Protected > Package > Private.To explain before the explanation: the word "use" here means that the class is instantiated (instantiating an object), accessing the property, and invoking the method.First, the access rights of the Java class are explained. Classes in Java have only two access r

Statement: Because the translation of Chinese translations is too redundant, the useful knowledge points are listed.directory of this document: First, using an example of inserting elements to explain the nature of listfirst, the essence of list is explained by the example of inserting element代码一：count = 10**5nums = []for i in range(count):nums.append(i)nums.reverse() #翻转功能代码二：count = 10**5nums = []for i in range(count):nums.insert(0, i)Analysis : The

. This will lead to a performance boost, and Virsto's technology brings significant positive changes to snapshot technology in order to further improve performance. We no longer have to use outdated vsphere snapshots. We have a metadata-based snapshot and cloning technology that will be faster, more space-saving, and have very little impact on performance.To read the full text, please click:Depth: VMware VSAN 6.0 Performance features explained friendl

all additions and deletions to the database.1. Open Bin-log log:2. View Bin-log logafter connecting to a successful databaseto see if the Log_bin is open successfullyView Bin-log Logs3. Log refresh related to Bin_logat this point, there will be one more up-to-date Bin_log log you can see more mysql-bin.xxxxxx in the/usr/local/mysql/var.View the last Bin-log logClear all Bin-log logsEveryone just follow the steps to operate their own, basically can succeed, if you encounter problems, you can lea

*pszname);~student ();Publicstatic void Printfallstudents ();PrivateChar M_name[max_name_size];Student *next;Student *prev;Static Student *m_head;};Student::student (char *pszname){strcpy (This->m_name, pszname);Create a doubly linked list, and the new data is inserted from the list header.This->next = M_head;This->prev = NULL;if (m_head! = NULL)M_head->prev = this;M_head = this;}Student::~student ()//The process of destruction is the separation process of the node{if (this = = M_head)//The nod

hard disk is divided into two parts: the first part Indoe node; the second part blockBlock is used to store the actual data, such as photos, video and other ordinary file data, and Indoe is used to store these data attribute information, Indoe contains the property information including file size, owner, attribution Group of user groups, read and Write permissions, file type, modification time, It also contains the pointer function for the specified file entity (the Indoe node ———— block), etc.

the main execution program that is connected under/usr/local/bin.· All settings of the system are in/etc directory.· Do not modify anything in the root directory ("/") or/usr directory unless you really know what to do. These directories are best kept consistent with Linux publishing.· Most tools and applications are installed in the directory:/bin,/usr/sbin,/sbin,/usr/x11/bin,/usr/local/bin.· All the files are under a single directory tree. There is no so-called "driver".Reference article Addr

] [+ |-| =] [mode] file name?Action object who is either or their combination of the following letters:U means "user", which is the owner of the file or directory.G means "same group user", that is, all users with the same group ID as the file owner.O means "other (others) users".A means "all users". He is the system default value.+ Add a permission.-Cancels a permission.= gives the given permission and cancels all other permissions, if any.Setting the permissions represented by mode can be any

value for(intK=i; k1][J] + sum[j]-sum[i-1]);//State transfer equation F[i][j] = min{f[i][k] + f[k + 1][j] + sum[j]-sum[i-1]} | I G[I][J] = max (G[i][j],g[i][k] + g[k +1][J] + sum[j]-sum[i-1]); }if(Ans_maxintMain () {scanf ("%d", n); for(intI=1; i"%d", w[i]); W[i+n]=w[i]; } for(intI=1; i2*n; i++) {Sum[i]=sum[i-1]+w[i]; } DP (); for(intI=1; iif(Ans_min>f[i][i+n-1]) Ans_min=f[i][i+n-1]; } printf ("%d\n", ans_min); printf"%d\n", Ans_max);return 0;}The above code is written in the fir

Foo = function () {}, in reference to Example 2, we can know that the result of this problem should be reported TypeError (because Foo is declared but not assigned, so foo is undefined).We mentioned the Var declaration, the function declaration, and then let's talk about the A and const declarations. This I have written one side of the article, you can click here to see the next.SummarizeSo let's sum up. JS will promote the declaration of the variable to the top of the JS execution, so

One: Type1 Immutable data typesString,int, tuple constantsA further exploration of the immutable character of stringsString[1] = ' new_one ' can?2 variable data type variablesDict ListTwo re-study stringsWhat exactly is a sequence?13 matching differences ', ', ', ' "" "" "2 offset starting from 03 How to modify the Replace,find of a stringThree-format scrutiny1% formatting mode2 format formatting3 Why to use format4 There is another way, the dictionary comes.Four further discussions open fileInt

Change and deleteIncreaseThe X.append function is to append a new element to the list at the end of the original listX.extend () Adds a list of elements to another list, keeps the referenced original list intact, and extend can also be applied to tuples, dictionaries, collections ...X.insert (subscript, Element) insert adds an element at a specified position based on the subscriptBy deleting:X.remove ("content") add a specific element to delete, only 1 elements can be deleted at a time, if a lis

Remember that in the previous introduction of the C H o d command, the permissions bits and files of the directory are different. Now let's take a look at the difference. The Read permission bit for a directory means that the contents can be listed. The Write permission bit means that you can create files in this directory, and you can cancel the corresponding write permission bits if you do not want other users to create files in your directory. Executing a permission bit means searching for an