NET TIME synchronizes a computer's clock with another computer or domain. If used without parameters in a domain Windows Server, displays the current date and time of day set on the computer that is designated as the time server for this domain. This command allows you to set the NTP time server for the computer.

NET TIME Command Syntax

net time [(\\computer_name | /domain[:domain_name] | /rtsdomain[:domain_name])]

net time [\\computer_name]

net time [\\computer_name] ], where

• \\computer_name- indicates the name of the server on which you want to check the time or with which you want to synchronize the timer.
• /domain[:domain_name]- specifies the name of the domain with which the clock is synchronized.
• /rtsdomain[:domain_name]- specifies the domain of the reliable time server (RTS) with which the clock will be synchronized.
• /set- synchronizes the clock with the time of the specified computer or domain.
• /querysntp- displays the name of the NTP (Network Time Protocol) server configured for local computer, or the computer specified in the \\computer_name parameter.
• /setsntp[:list_NTP_servers]- specifies a list of NTP time servers to use on the local computer.

NET TIME Command Examples

• net help time - display help for the specified net command;
• net time \\PC1 - displays the current time of the server on the network for computer PC1;
• net time /querysntp - displays the NTP server name for the local computer on the screen;
• net time \\Proton /set - synchronizes the local computer clock with the Proton computer time.

Net time system error 5 access denied

People often ask why " System error 5. Access denied" when using Net commands time. I answer, everything is in the rights of the user under which the command is launched. As an example, I tried to run the command first with local administrator rights to

As we all remember from our school history course, humanity began keeping track of exact time by observing the movement of celestial bodies and numbering hours in earthly days. As technology developed, the need for increasingly accurate time only increased. Today the whole world lives according to atomic clocks, in which, according to the international system of SI units, the exact time is calculated according to electromagnetic radiation, which arises during the transition between two hyperfine levels of the ground state of atoms.

Without atomic clocks, work is currently impossible modern systems navigation (including GPS, GLONASS, Galileo), satellite and terrestrial telecommunication systems, in particular mobile communication stations.

Several countries have established national centers for time and frequency standards, as well as time services that periodically broadcast time signals by radio.

Work to improve the characteristics of atomic clocks is ongoing; systems and methods for synchronizing various types of electronic equipment with atomic clocks are also being improved. Moreover, recently, some watch brands have begun to produce watches with the function of automatically calibrating the accuracy of the movement using precise time signals from atomic clocks. But in fact, any clock can be synchronized with an atomic clock.

To do this, it is enough to know how the time is set specific model(for example, we took the Romanson wristwatch - mir-chasov.ks.ua/shop/romanson- chronograph), and have at hand data on the exact time from an atomic clock (precise time server/site). Simply put, it requires a wristwatch user manual and an atomic clock - nothing complicated.

So, how to synchronize your wrist watch with an atomic clock and set the exact time.

1. First, prepare the watch for setting. In analog models, the time is set by the crown, which, as a rule, must be pulled out of the case to a certain position (for our Romanson, this is the second position out of three possible); For digital watches, the time is set by one of the buttons on the case, which, on the contrary, must be pressed. Let us remind you that the arrows should only be moved along the way.

2. Set the hours and minutes in accordance with current time, let the watch run until the second hand (or seconds counter) reaches the zero position (mark 12 on the analog dial and 0 on the digital dial). The position of the minute hand may change slightly, but this is normal, we will set the minutes again. After setting the second hand to 12, we stop the watch (in Romanson, for this you need to move the crown to the extreme position).

3. Go to the exact time server; we used data from the time.is service (by the way, at the same time you will find out how accurately the clock on your computer, smartphone or tablet is running).

4. We catch the moment when the next minute changes on the dial of the atomic clock, and the seconds “reset to zero”, and set our watch a minute ahead. For example, if the exact time server showed 12:35:00, we set it to 12:36. Next, we wait until the moment of the next “zeroing” of seconds on the atomic clock approaches and start our clock. That is, at 12:35:59 we press the crown of our Romanson, returning it to the lower position and thereby starting the mechanism. That's all, now our clocks are synchronized with atomic clocks.

And in conclusion, especially for fans of super-precise time, let us remind/clarify that there is always an error between the readings of real atomic clocks and the readings of any exact time server. In addition, there are errors between the server readings and the clock readings on the screen of the device from which this server was accessed. Simply put, by the time the signal arrives at the server, and then from the server to your communication device (the transit time depends on the remoteness of the server, the bandwidth and congestion of Internet channels, and a number of other parameters), the reference atomic clock will already advance, and your clock will for a fraction of a second, but they will lag behind. Therefore, the watch procedure described above is not the most perfect, but, nevertheless, at the everyday level it is enough, especially if you use a mechanical watch. The article uses materials from the website of the World of Watches company.

Let us recall that by a reference system we mean a reference body with which a coordinate system and a number of fixed identical clocks synchronized with each other are associated. We will consider a clock to be any device that uses one or another periodic process.

When carrying out various physical measurements, the concept of simultaneity of two or more events is widely used. For example, to determine the length of a rod located along the axis X reference systems TO and moving relative to this system (Fig. 7.1), it is necessary simultaneously, that is, at the same moment in time , fix the coordinate values And rod ends:

. (7.1)

To do this, each reference system must have many clocks located at different points in space. All these clocks must run in concert, synchronously - their readings at each moment in time must be the same.

It is possible to synchronize clocks placed at different points in the reference system only with the help of some signals. The fastest signals suitable for this purpose are light or radio signals that travel at a known speed WITH. The choice of light signals is also due to the fact that their speed does not depend on the direction in space, and is also the same in all inertial reference systems.

Clock synchronization can be done as follows. Let us assume that, from the origin of the coordinate system of the point 0 on the radio at the moment a radio signal is transmitted. At the moment when this signal reaches the clock located from the point 0 at a known distance S, they are installed so that they show the time
, that is, taking into account the signal propagation time. As a result of such an operation, all clocks of a given reference frame will be synchronized at each moment in time.

§8. Lorentz transformation

The fact that the second postulate of the special theory of relativity is incompatible with the classical law of addition of velocities, and therefore with Galilean transformations, leads to the need to abandon these transformations. The problem arises of finding the true transformation formulas when moving from one inertial reference system to another, that is, formulas connecting the coordinates and time of the same event in two inertial reference systems.

New transformations were derived by Einstein based on the postulates he formulated. Formally, they coincided with the transformations found earlier by Lorentz in connection with attempts to explain the failure of the Michelson experiment. But only Einstein revealed their deep meaning.

Consider two inertial reference systems TO And TO"(Fig. 5.1). As before, the system TO" TO in the direction of the axis X at constant speed . Let us install identical clocks at different points of both reference systems and synchronize them: separately the system clocks TO and separately the system clock TO". Let us take the moment (
), when the origins (points 0 And 0" ) match up.

Since the system TO" moves relative to the system TO uniformly, the relationship between the coordinates And
should still, as in Galilean transformations, depend linearly on time, that is

, (8.1)

Where - some coefficient.

A similar expression can be written for the reverse transition from the system TO to the system TO":

. (8.2)

To determine the coefficient Let us assume that at the initial moment of time (
), when points 0 And 0" coincided, from the point 0 in the direction of the axis X a light signal was sent, which after a while , measured in the system TO, reached the point A with coordinate
. In system TO" this point had the coordinate
, Where - time measured in the system TO". Note that the speed WITH by virtue of the second postulate is the same.

Substituting the coordinates And into expressions (8.1) and (8.2), we obtain

,

.

Multiplying the right and left sides of these equalities and reducing by
, we get

,

(8.4)

Thus, the relationship between the coordinates
And has the form:

(8.5)

To find the connection between And Let's do the following. Having excluded from expressions (8.1) and (8.2) the quantity and deciding them after that regarding , we obtain, taking into account expression (8.4):

(8.6)

Coordinates And
And for the considered motion of systems TO And TO" remain equal to each other.

Thus, transformations for coordinates and time, called Lorentz transformations, have the form:

,
,
,
, (8.7)

Where

Inverse transformations, due to the equality of all inertial reference systems, should have a similar form, but taking into account the change in the sign of the speed V:

,
,
,
. (8.8)

Analysis of the Lorentz transformation formulas allows us to draw a number of important conclusions.

Firstly, a feature of Lorentz transformations is that when
they go over to the Galilean transformations (5.1). This means that the theory of relativity does not reject Galileo’s transformations, but includes them in true transformations as a special case, valid for
.

Secondly, from the Lorentz transformations it follows that when
radical expressions become negative and formulas lose their physical meaning. This means that the movement of bodies at a speed greater than the speed of light in a vacuum is impossible.

Thirdly, the time conversion formulas include a spatial coordinate, which reflects the inextricable connection between space and time.

When you study new technology or a programming language, the basic concepts are always relatively routine in nature and therefore, in my opinion, quickly discourage beginners from learning. The purpose of this article is to interest and captivate the reader in the study of programming using the example of developing elementary graphics in dynamic mode. The article is suitable for novice developers who have become familiar with the basics of HTML5 and JavaScript, and who are tired of seeing static text on the page when outputting arrays, objects, results of arithmetic operations, etc. to the browser console. Next, we will implement the simplest animation, but useful for understanding the language. What will we do? Let's consider the process of creating the simplest analog clock using HTML5 and JavaScript. We will draw clocks using graphic primitives, without using CSS tools. We'll remember a little geometry to display our graphics, we'll remember a little math to implement the display logic of our animated clock. And in general, we will try to reduce entropy in knowledge JavaScript language. For development, we will need a text editor like Notepad++ or Sublime Text 3. Implementation of a digital clock Let's create three files in text editor. (All three files must be in the same folder).

index.html- main page
clockscript.js- script with operating logic
style.css- style file

First, let's display the current time in normal time div-block in .html file. Even such a small task has its pitfalls. If you just throw the clock display function into the onload event of the tag body, then the current time will be displayed in the line, but will remain static. AND div-the block to which we sent a string with the current time will not update itself.

Achieve self-updating page element can be wrapped by wrapping the time display function in an anonymous method, which is assigned to the onload property of the root Window object.

One implementation option could be as follows. File index.html:

Clock JavaScript Draft. Working with canvas:
This will be the current time

File style.css:

#clock( font-family:Tahoma, sans-serif; font-size:20px; font-weight:bold; color:#0000cc; )
File clockscript.js:

Window.onload = function())( window.setInterval(function())( var d = new Date(); document.getElementById("clock").innerHTML = d.toLocaleTimeString(); ) , 1000); )
Let's sort out the work clockscript.js:

We execute the internal JavaScript code by binding to the onload event of the root Window object:

Window.onload = function())(/*blah blah blah*/)
A Window object method that executes code at specified intervals (specified in milliseconds):

Window.setInterval(function())(/*Here are actions wrapped in a function that needs to be executed every 1000 milliseconds*/) , 1000);
The Date object is used to perform various date and time manipulations. Using the constructor, we create an instance of it and call it d:

Var d = new Date();
We find a DOM object by its id. This is exactly the object into which we want to output our time. This could be a paragraph, a heading, or some other element. I have this div-block. After retrieving an element by id, we use its innerHTML property to retrieve the entire content of the element along with the markup inside. And we pass the result of the method there toLocaleTimeString() which returns a formatted representation of the time:

Document.getElementById("clock").innerHTML = d.toLocaleTimeString();
This is what you should get (the time changes dynamically every second):

Implementing an analog clock From now on, we will use Canvas (HTML), which will serve as our canvas for creativity.

To see our canvas in the file index.html inside the body we must place the following tag somewhere, immediately defining its dimensions:

Now in file clockscript.js You need to get the Canvas object's context before attempting to draw. Let's do this at the beginning of our clock display function. Then the file clockscript.js will change as follows:

Function displayCanvas())( var canvasHTML = document.getElementById("myCanvas"); var contextHTML = canvasHTML.getContext("2d"); contextHTML.strokeRect(0,0,canvasHTML.width, canvasHTML.height); //This will be all clock logic and display code via graphics primitives return; ) window.onload = function())( window.setInterval(function())( var d = new Date(); document.getElementById("clock").innerHTML = d.toLocaleTimeString (); displayCanvas(); ) , 1000); )
Well, let's remember mathematics? It is important for us to understand the connection between the divisions of certain hands and the angle of their rotation on the future dial.

Angle of rotation of all hands in 1 second:

• The second hand will rotate by an angle - (1/60)*360 o = 6 o
• The minute hand will rotate by an angle - (1/60)*6 o = 0.1 o
• The hour hand will turn by an angle - (1/60)*0.1 o ≈ 0.0017 o

First problem:

That is, even in 1 second, all the arrows must turn, each to the corresponding angle. And if this is not taken into account, then the first pitfall that we will get in the display will be ugly animation. For example, when the time is 19:30, the hour hand will point exactly to 19 o'clock, although in real life it should already be halfway to 20 o'clock. Likewise, the smooth movement of the minute hand will look more pleasant. Well, let the second hand click in discrete movements, as in most real mechanical watches. Solution to the problem: add to the angles of rotation of the current arrow the angle of rotation of the faster arrow, multiplied by a coefficient indicating its share of the angle of the current arrow.

Implementation:

Var t_sec = 6*d.getSeconds(); //Determine the angle for seconds var t_min = 6*(d.getMinutes() + (1/60)*d.getSeconds()); //Determine the angle for minutes var t_hour = 30*(d.getHours() + (1/60)*d.getMinutes()); //Determine the angle for the clock
Second problem:

The angle of the rotating radius vector (clock hands) is measured from the positive direction in a counterclockwise direction. If we do not take this into account in our logic, we will set the clock back in time.

And yet, we count hours, minutes and seconds from the number 12, the top position. Solution to the problem: in our formulas we must take this into account as a shift of +π/2 (90 o). And put a “-” sign in front of the angle value so that the clock runs exactly clockwise. And, of course, take into account that the transfer of an angle in degrees to trigonometric functions of programming languages ​​is carried out by multiplying by the coefficient “π/180 o”.

Implementation using the second hand as an example:

ContextHTML.moveTo(xCenterClock, yCenterClock); contextHTML.lineTo(xCenterClock + lengthSeconds*Math.cos(Math.PI/2 - t_sec*(Math.PI/180)), yCenterClock - lengthSeconds*Math.sin(Math.PI/2 - t_sec*(Math.PI/ 180)));
Third problem:

When marking the dial patterns, you need to somehow highlight the patterns opposite the clock. There are 60 pictures in total for seconds and minutes. 12 - for hours. These 12 should somehow stand out from all the others. Also, the symmetry of digitization depends on the width of the digits. Obviously, the numbers 10, 11 and 12 are wider than 1, 2, 3, etc. We must not forget about this.

Solution to the problem and option for digitizing the dial:

For(var th = 1; th