1. The public port of DNS protocol is 53, which is commonly used for UDP encapsulation (TCP encapsulation can also be used ).
DNS (Domain Name System) is a distributed database (IP-name)
2. concepts:
(1) The DNS domain name can contain a maximum of 63 characters, regardless of case. For example, top-level (level-1) domain names are at the rightmost of sun.tuc.noao.edu, and second-level domain names are at the left, third-level domain name .... A maximum of 128 domain names can be available (0-1
, then small, first difficult and then easy", that is, the layout of important unit circuits and core components should be prioritized.
B. The layout should refer to the schematic diagram and arrange the main components according to the main signal flow pattern of the Board.
C. the layout should meet the following requirements as much as possible: the total connection line should be as short as possible, and the key signal line should be the shortest; the high voltage, high current signal should
in and out
CTRL + scroll wheel to zoom in, zoom out, and scale down to a certain extent. The size of is displayed on the screen, which can be directly compared with the actual components.
Supplement: Cangzhou YuCircuit BoardProcessing technology: Line 6 mil, Distance 6 mil, inner diameter 12mil, outer diameter 22milFilter capacitor, decoupling capacitor, and bypass CapacitorThe filter capacitor is
is not at ease. Because if there are ten moreThe first fault may occur in one or two months. On the contrary, if there is an average 8th fault in 5000100 defects are acceptable.Therefore, the user is most concerned about: "No matter how many defects you deliver the software, their total MTBF or λ isHow much? "Iii. Analysis of the fault rate of various software DefectsSeveral defects of a software are arranged in ascending order according to the failure rate: λ 1 ≥λ 2 ≥λ 3 ≥ ......In theory, we
The computation of PCB streaming capability has always lacked authoritative technical methods and formulas. Experienced CAD engineers rely on their personal experience to make more accurate judgments. However, it is difficult for new users to use CAD.
The current Loading Capacity of PCB depends on the following factors: line width, line thickness (copper foil thickness), and allowable temperature rise. As we all know, the wider the PCB strip, the larger the streaming capacity. If 10
the res pin (#93), the better;
9. Try to keep the output transformer close to RJ45;
10. The sending and receiving signal lines are parallel and of an equal length. They should be as short as possible and distributed on the component plane. The receiving signal line should be at least 25 mil wide and the sending line should be at least mil;
11. The two ground wires are parallel and accompanied with tra
is far away;
2. Compression sensing can be improved. For example, features pool is used to select the optimal feature like random forest;
3. The new sample is biased towards the current one, so it is easy to forget the samples that have been learned before. Once the deviation occurs, the samples will be farther and farther away;
4. I recently studied tracking by detection and read compressive tracking. It seems very innovative. This simple method can achieve better results. The experiment part
. Only Chinese characters are entered:
5. Email Address verification:
var Regu =
"^" ([0-9a-za-z]+) | ( [0-9a-za-z]+[_.0-9a-za-z-]*[0-9a-za-z]+)] @ ([a-za-z0-9-]+[.]) + ([a-za-z]{2}|net|net|com|com|gov|gov|mil|mil|org|org|edu|edu|int|int) $ "
var re = new RegExp (regu);
if (S.search (re)!=-1) {return
true;
} else {
window.alert ("Please enter a valid e-mail address!"). ") return
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