Theory and case of digital currency
digital currency is an alternative currency in the form of electronic currency (which can be used for real goods and services transactions)
digital currency has the main characteristics of network packets. This kind of data packet is composed of data code and identification code. The data code is the content we need to transmit, while the identification code indicates where the data packet comes from and goes
based on the characteristics of digital currency, the direct benefit of digital currency to the central bank is not only to save the cost of note issuance, circulation and settlement, but also to enhance the central bank's ability to control funds
Electronic money and virtual money are called digital money. According to the definition of the European Central Bank, virtual money is issued by non central banks, credit institutions and e-money institutions, which can be used as the numerical expression of the value of currency substitutes in some cases{rrrrrrr}
extended information:
the process of digital currency trading through the platform is as follows:
(1) investors should register accounts first, and obtain digital currency accounts and US dollar or other foreign exchange accounts at the same time
(2) users can buy and sell digital currency with the money in their cash account, just like buying and selling stocks and futures
(3) the trading platform will sort the buying requests and selling requests according to the rules and start to match them. If they meet the requirements, the transaction will be concluded
(4) e to the difference between the buy and sell volumes submitted by users, a buy or sell request may be partially executed
1. The concept range is different. bitcoin is a kind of digital currency, and the concept of digital currency covers bitcoin
However, some digital currencies have independent issuers The biggest difference between bitcoin and other virtual currencies is that the total quantity of bitcoin is very limited and it has a strong scarcity. The monetary system used to have no more than 10.5 million in four years, after which the total number will be permanently limited to 21 milliondigital currency is abbreviated as digiccy, which is the abbreviation of "digital currency" in English. It is an alternative currency in the form of electronic currency. Both digital gold coin and cryptocurrency belong to digiccy. Bitcoin is a digital currency
digital currency is different from the virtual currency in the virtual world, because it can be used for real goods and services transactions, not limited to online games. The early digital currency (digital gold currency) is a form of electronic currency named after the weight of gold
today's digital currencies, such as bitcoin, lettercoin and ppcoin, are electronic currencies created, issued and circulated by means of check sum cryptography. It is characterized by the use of P2P peer-to-peer network technology to issue, manage and circulate currency. In theory, it avoids bureaucratic examination and approval, so that everyone has the right to issue currency
illegal digital currency
in recent years, "virtual currency" represented by bitcoin, Ethernet currency and Leyte currency has been traded centrally on some Internet platforms. With the help of financial technology, the price of these "currencies" has graally spread to investment, financing and other financial fields, which has aroused wide attention from all walks of life
not long ago, the people's Bank of China and other seven ministries and commissions jointly issued the announcement on preventing the financing risk of token issuance, which clearly regulated the relevant behaviors. Experts pointed out that "virtual currency" is not legal tender (legal currency) issued by monetary authorities, but a specific virtual commodity in essence
therefore, it is undoubtedly a great legal and economic risk to think that "virtual currency" has or will have the nature of legal tender and to carry out speculation, network fund-raising, lending and financing
1. Digital currency
digital currency is an alternative currency in the form of electronic currency. Both digital gold coin and password currency belong to digital currency
digital currency is different from the virtual currency in the virtual world, because it can be used for real goods and services transactions, not limited to online games. The early digital currency (digital gold currency) is a form of electronic currency named after the weight of gold. Today's digital currency, such as bitcoin, lightcoin and ppcoin, is an electronic currency created, issued and circulated by check sum cryptography
features: the use of P2P peer-to-peer network technology to issue, manage and circulate currency theoretically avoids bureaucratic examination and approval, so that everyone has the right to issue currency
Electronic money means that a certain amount of cash or deposit is exchanged from the issuer and the data representing the same amount is obtained. By using some electronic methods, the data is directly transferred to the payment object, so that the debt can be paid off. Strictly speaking, consumers pay traditional money to the issuers of electronic money, and the issuers store the equal value of traditional money in the electronic devices held by consumers in electronic form. In short, when we deposit money into our bank account, there will be an extra number in the bank account, which means how much money we have saved. In this process, we give the banknotes in our hands to the bank, and the bank adds a number to our bank card, which is our electronic currencyfeatures:
< UL >e-money and paper money (or physical money) can be easily converted to each other
the data of electronic currency corresponds to the same amount of physical currency
we need to pay physical money to the issuers of e-money (banks and other financial institutions) in order to exchange for the same amount of e-money
3. The similarity between digital currency and electronic currency: both exist in the form of electronic data
The differences between digital currency and electronic currency are as follows:electronic currency has an issuing institution, and the corresponding amount of physical currency in the institution can be exchanged with physical currency; However, digital currency has no specific issuing institution (decentralization) and can only exist in network data
at present, there is no international consensus on whether digital currency is a currency or not, so in China, the main form of digital currency is "investment proct", which is a rather risky investment proct, and only a few businesses are willing to accept digital currency consumption; Of course, some countries (Germany, etc.) have officially recognized the currency status of digital currency
it's not a reality. Up to now, I still think it's stupid to make money by buying and selling domain names. I know it happens sometimes. It's like a high-risk, low return investment
as a result, the Internet did. Now, 20 years on, domain names are cheap, and search engines make them brand specific Note: the author means that the convenience of search engines makes domain names cheaper and cheaper. Domain names are only related to brands.)
What does this have to do with the value of bitcoin
this is an example of how people's views on value change with the development of technology
at this point, most people see bitcoin as money. The chairman of the US SEC said, "yes, that's how drug gangs use it. Everyone I know thinks so.". It's called "bit coin" for a reason
bitcoin maximalists call it hard currency, critics call it fake money, and veteran players call it cyber currency
W bq89998 push the latest currency from time to time to ensure the minimum 10 times
the design basis of 054 frigate may come from the f-16u frigate previously used for export. Compared with the previous domestic Jiangwei class frigates, the 054 frigate is more concise and avant-garde in appearance, completely getting rid of the impression that the superstructure of Jianghu class and Jiangwei class frigates is scattered and low. Compared with the Chinese Navy's new 052B / C missile destroyer, the new 054 frigate has a more concise outline. It adopts a stepped superstructure integrated with the ship's side. The bridge, tower shaped front mast and composite rear mast / chimney structure are all inclined (and the inclined angle is generally quite obvious), avoiding acute angle and complex structure, Some equipment on the surface of the warship, such as boat crane, is also covered by bulwarks, which makes the stealth design of 054 frigate close to the advanced level of the West. The displacement and hull of 054 frigate is much larger than that of Jiangwei class II frigate with a displacement of 2250 tons. It has better ocean navigation ability and can accompany the ocean fleet. However, after the first two warships of 054 frigate were built and launched, it can be inferred that 054 frigate is still a kind of transitional warship from the eight joint haihongqi 7 air defense missile launcher. Starting from the third ship, the second batch of 054 frigates have made many significant improvements in design and equipment, among which the biggest improvement is the addition of domestic vertical air defense missile launcher, which greatly strengthens the air defense capability of this type of frigates. The improved 054 frigate is the present 054A stealth frigate. 054A stealth frigate is also a new type of surface combat ship equipped by the Chinese Navy, and a few of them can build more than two, which shows that its design has become mature. With the improvement of comprehensive operational performance and low cost, 054A frigate graally plays the role of general destroyer in Chinese fleet
while China is striving to narrow the gap with the world's naval power, Japan, a former naval power and China's neighbor, has built a strong 88 fleet as early as the 1980s to meet its demand for "1000 nautical miles ocean escort". Based on five general purpose destroyers, two air defense destroyers and one helicopter destroyer, this fleet has strong comprehensive combat capability. With the development of the times, Japan's newly-built "King Kong" class and "aitao" class air defense destroyers and "Gaobo" class destroyers have been serving in the sea one after another, and Japan's sea has formed a more sophisticated 90 fleet accordingly. Overall layout and stealth capability first of all, 054A stealth frigate: Based on the data provided by all parties, it is assumed that the data should be 3600 tons of standard displacement and 4000 tons of full load displacement (there is also a saying that the index row is 3900 tons and 4500 tons of full load displacement). The ship is 134m long, 16m wide, 5m draught, and the aspect ratio is close to 8.6. Maximum speed 27 knots, 18 knots, enrance 3800 nautical miles, 190 crew
in terms of overall situation, since the Chinese Navy had a lot of exchanges with the European navies in the 1980s, especially the French, Italian and British navies, and was deeply influenced by their design, when Jiangwei class frigates appeared, they inadvertently revealed some traces of the design of Western ships, When the 054 frigate appeared, it obviously borrowed some of the body designs of some French "Lafayette" frigates: popular flying shear bow, freeboard high and floating out, square stern linear structure, and small aspect ratio. Its bow is high (the height is similar to that of Russian 956 "modern" class destroyer) and its transverse section is deep V-shaped, which can well prevent buffeting and waves. Its excellent hull line shape, relatively small aspect ratio and reasonable use of fin stabilizer can ensure its seakeeping to meet the needs of ocean navigation, which has been confirmed by the second and third batch of naval escort operations to the Persian Gulf
in terms of stealth design, the effect of Lafite class is also obvious, with freeboard camber of 10 °～ twenty °， Superstructure sidewall inclination 7 °～ fifteen °， Both of them are combined into an organic whole by the corner line which is almost used to pass through the whole ship. By making its cross section present a rhombic structure, the direction of the radar radiation wave can be changed, the scattering space can be reced, the echo intensity can be reced, and the radar reflection cross section can be reced. At the same time, the corner line starts from the back part of the wall of the ship's bow side, which is strongly floating, and passes through the shielding net outside the space of the lifeboat on the side side of the midship, which is flush with the helicopter platform. Its purpose is to cover the chain winch, cable pile, windlass and other equipment on the bow deck which is not concive to radar stealth, and the design idea of deliberately recing the target signal characteristics runs through the design. In addition, radar absorbing coating is used to further improve radar stealth performance. In terms of acoustic stealth treatment, diesel engines and generators use double-layer raft devices to rece vibration and noise, and the use of new low-noise 5 large side slope low-speed propeller also strengthens this purpose. In the infrared stealth processing, its huge chimney shows that it has spray cooling facilities to suppress infrared radiation
let's look at the "high wave" class: 151 meters in length, 17.4 meters in width and 5.3 meters in draft. The standard displacement is 4650 tons, and the full load displacement is 5500 tons. The ratio of length to width is 8.88, the maximum speed is 30 knots, carrying 175 people. In addition, the layout of engine room is similar. The differences are mainly reflected in the bridge, helicopter hangar and chimney. The ship has excellent ocean navigation quality to ensure that it can normally use oqr-2 low-frequency towed sonar to carry out anti submarine operation in bad sea conditions
in the stealth design, the "high wave" class also uses two methods: shape modification and absorbing coating (such as the use on the mast) to achieve the goal of weakening the radar reflection. Its hull is 8 ° The cross section is V-shaped e to the outward inclination of the cross section; The superstructure should be designed to eliminate the radar reflection as much as possible; In terms of infrared and noise stealth, relevant infrared suppression devices, shock absorbing floating rafts, low-noise and highly skewed propellers, and aerosol noise rection systems are also adopted to improve the comprehensive stealth capability. The overall stealth effect has reached the world advanced level. Power system in the power system: 054A is also affected by Lafite class and adopts the CODAD power propulsion mode, which is composed of four pilstek 16pa6v280stc diesel engines proced by Shaanxi Diesel according to the license, with the maximum power of 6400kw and the total power of 25600kw. Two new 5-blade adjustable pitch and large pitch low speed propellers are driven by two shafts. The design of the air intake in the lower front of the chimney is similar to Burke's style. The large size of the chimney indicates that it has a spray cooling facility to suppress the infrared radiation. In addition, there are two mtu-396 diesel generator sets with power of 1500kW, reaching the same level as "high wave". Don't underestimate this change. One of the reasons why the modernization of Chinese Navy destroyers and frigates was very small in the past was that the power of the power station was very small (400KW), which could only meet the power supply demand of the electromechanical, electronic and weapon equipment on board when they were newly built. The reserve power could not meet the needs of the newly improved equipment on board. As a result, the modernization was only related to communication and communication In the field of electronic warfare and other systems
many people have different opinions on the use of CODAD power mode for 054A. In fact, the power mode of CODAD first appeared on the French Navy's Casar class air defense missile destroyer. Its four high-power pierstick 18pa6v280btc diesel engines can output 31752kw of total power, so that the 5000 ton Casar can reach 29.5 knots. It was a good area air defense ship for fuhee and later Charles de Gaulle (CVN). Later, the Lafite class adopted the CODAD power unit composed of four 16pa6v280stc diesel engines. In fact, Lafite class still exists in the formation of French aircraft carriers. Considering that the output of domestic gas turbine can not meet the Navy's needs at present, the first thing is to ensure the demand of domestic large ocean destroyer. At the same time, the technical support department of the Chinese navy has rich experience and complete technical means for long-term maintenance of such power plants. Therefore, it is the most appropriate project to use advanced and mature high-power medium and high-speed diesel engine as the main power device of medium-sized warship
rihai has fully implemented COGAG since it was on the "Chaowu" class general destroyer. At that time, it was referring to the model of dd-963 class of the United States. Considering that its full capacity is less than 4200 tons, which is almost half of the latter, rihai chose four "Spey" SMIA gas turbines from the traditional supplier R.R., with a total power of 39100kw. It can solve the contradiction between the quiet environment of high-speed pursuit of nuclear submarine and low-speed towed linear array sonar. When the new "village rain" class was built later, because the full discharge increased to 5100 tons, more power was needed to ensure that the speed could reach 30 knots. Therefore, two of the main engines were replaced by lm2500 with higher power, in order to keep the original characteristics in the case of increased displacement. The "high wave" class basically "copies" such a mode: four main engines are installed in two power cabins respectively, and the general layout of front and rear port and starboard is adopted. The first engine room is arranged on the front port side, with No.1 and No.2 engines built in to drive the left propulsion shaft. The second engine room is arranged on the starboard side of the rear, with No. 3 and No. 4 engines built in to drive the right propulsion shaft. 1. Unit 4 is lm2500 proced by GE; 2. Unit 3 is sm1c proced by R.R. The advantages of this arrangement are: first, it improves the anti damage ability of the aircraft; second, as a cruiser, sm1c has lower fuel consumption and noise than lm2500; its navigation quietness and enrance are better than "Chaowu"; third, the total power is 44400kw when the vehicle is combined to ensure that the maximum speed is 30 knots, meeting the needs of pursuing submarines. The antisubmarine capability is the same as the "high wave" class. In the general layout and power plant selection, model 054A attaches great importance to the quiet environment required for the low speed towed linear array sonar's submarine search time outline, and the corresponding development work has been carried out, and the purpose has been basically achieved through various efforts. The common equipment and use of the ball bow active intermediate frequency sonar and towed linear array towed sonar can search and lock easily