Based on Ethereum alliance chain

1.

blockchain includes public blockchain, joint (instry) blockchain and private blockchain. Public chain point-to-point e-cash system: bitcoin, smart contract and decentralized application platform: Ethereum

blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies

blockchain is an important concept of bitcoin. In essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of bitcoin network transaction information, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

according to the different degree of blockchain network centralization, three kinds of blockchains under different application scenarios are differentiated:

1. The blockchain with the whole network open and without user authorization mechanism is called public chain

2. The authorized nodes are allowed to join the network, and the information can be viewed according to the authority. It is often used in the inter agency blockchain, which is called alliance chain or instry chain

3. All the nodes in the network are in the hands of one organization, which is called private chain

alliance chain and private chain are also called licensing chain, and public chain is called non licensing chain

blockchain features

1, decentralization. Blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage. Decentralization is the most prominent and essential feature of blockchain

2. Openness. Blockchain technology is based on open source. In addition to the private information of all parties involved in the transaction is encrypted, the data of blockchain is open to everyone. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent

3. Independence. Based on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention

4. Safety. As long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily manipulated and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes

5. Anonymity. Unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information can be transferred anonymously

2. Many blockchain projects are developed on the basis of Ethereum's open source technology. Ethereum is a common public chain technology, and the deployment of applications on Ethereum has high requirements for developers. Developers need to consider many technical details and business processing logic, as well as security vulnerabilities such as smart contract overflow
the trust union credit alliance chain is located in the financial public chain, which is oriented to the high-frequency financial application scenarios in the field of credit and assets. It does not use eth, EOS, Neo and other general public chains, but uses the account structure of star network, adopts the lightweight intelligent contract layer, and the whole technical architecture is molarized according to "high aggregation and low coupling", This enables the trust union credit alliance chain to adapt to the requirements of rapid development, rapid implementation and timely response of Internet financial procts.

3. At the top of Ethereum is DAPP. It exchanges with the smart contract layer through Web3. JS. All smart contracts run on EVM (Ethereum virtual machine) and use RPC calls. Below EVM and RPC are the four core contents of Ethereum, including: blockchain, consensus algorithm, mining and network layer. Except DAPP, all other parts are in the Ethereum client. The most popular Ethereum client is geth (go Ethereum)

4.

Ethereum is an open source public blockchain platform with smart contract function. It provides decentralized virtual machine (Ethereum virtual machine) to process point-to-point contract through its special cryptocurrency ether (also known as "Ethereum")

The token on the

blockchain is called ether, and the code is eth. It can be traded in many foreign exchange markets of cryptocurrency, and it is also the medium used to pay transaction fees and computing services on Ethereum

the concept of Ethereum was first proposed by vitalik buterin, a programmer, from 2013 to 2014, inspired by bitcoin, with the general meaning of "next generation cryptocurrency and decentralized application platform", and began to develop through ICO crowdfunding in 2014. As of February 2018, Ethernet is the second highest cryptocurrency in market value, second only to bitcoin

extended data:

Ethereum platform has no characteristics and value. Like programming languages, it's up to entrepreneurs and developers to decide what to use. However, it is clear that some application types benefit more from the functions of Ethereum than others. Ethereum is especially suitable for those applications that automatically interact directly between points or promote group coordination activities across networks

for example, coordinate the application of point-to-point market, or the automation of complex financial contracts. Bitcoin enables indivials to exchange money without the help of financial institutions, banks or governments. The impact of Ethereum may be more profound

in theory, any complex financial activities or transactions can be automatically and reliably carried out on Ethereum with coding. In addition to financial applications, any application scenario with high requirements for trust, security and persistence, such as asset registration, voting, management and Internet of things, will be affected by Ethereum platform on a large scale

5. Whether a currency is counterfeit depends on whether it meets the basic characteristics of blockchain. Blockchain is divided into public chain and private chain. The public chain is a block chain based on the principle of decentralized open consensus, which has two characteristics: 1. Decentralized, single point can not be controlled; 2; 2. Open, all people or institutions can participate in any part of the blockchain ecology; Private chain or alliance chain is a local decentralized and non open block chain based on internal or self trust. It has two characteristics: 1. Local decentralization. For example, several banks run one node and have equal computing power; 2. In closed operation, only officially designated participants can participate in the core work of blockchain operation, and even block queries are limited or not open to the outside world at all; Ethereum started as a community project and is still on the road of decentralization. However, Ethereum chooses to become more and more decentralized and public chain like bitcoin. At present, Qube is the largest trading platform of Ethereum in China, followed by oke, and the trading volume of bitmex abroad is not small. Its recognition is second only to BTC.

6. Ethereum has established a programmable and Turing complete blockchain. On this blockchain, you can realize the proction of all kinds of digital assets through a simple program, and you can also accurately control the status of the blockchain assets circulating on Ethereum by writing a program, such as whether the asset is to be paid or locked or has a quota, whether the account is a treasure list or a white list Ethereum and other digital assets, etc. At the same time, Ethereum is a programmable, flexible and complete blockchain network foundation. On this basis, we can realize more functional procts of non regional fast chain assets. For example, I use Ethereum to set up smart contracts, which can be applied in personal daily economic life and enterprise economic activities. Ethereum is a new and open blockchain platform based on the concept of blockchain and blockchain assets. It allows anyone to build and run decentralized applications on the platform by using blockchain technology. In short, Ethereum technology is blockchain technology plus smart contract.

7.

The public chain is open to all, the private chain is open to indivials who meet specific conditions, and the alliance chain is open to authorized organizations or institutions

public chain, also known as public blockchains, refers to a consensus blockchain that can be read by anyone in the world, sent by anyone, and effectively confirmed

private chain, also known as fully private blockchains, refers to the blockchain in which the write permission is completely in the hands of an organization, and all nodes participating in the blockchain will be strictly controlled

alliance chain, or alliance blockchains, refers to a blockchain that is managed by several organizations or institutions. Each organization or institution controls one or more nodes and records transaction data together. Only these organizations and institutions can read, write and send transaction data in the alliance chain

< H2 > extended data:

blockchain has three types: public chain, private chain and alliance chain

blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies

blockchain is an important concept of bitcoin. It is essentially a disintermediated database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains the information of a bitcoin network transaction, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

< H2 > reference: blockchain network

8. The degree of decentralization of public chain. This kind of public blockchain, represented by bitcoin and Ethereum, is not controlled by a third party. All people in the world can read the data records on the chain, participate in transactions and compete for the bookkeeping rights of new blocks
program developers have no right to interfere with users, and each participant (i.e. node) can freely join and exit the network, and carry out relevant operations according to their wishes
private blockchain is on the contrary. The write permission of the network is fully controlled by an organization or institution, and the data read permission is regulated by the organization, either open to the outside world or with a certain degree of access restrictions
in short, it can be understood as a weakly centralized or multi centralized system. Because the participating nodes are strictly limited and few; Compared with public chain, private chain has shorter time to reach consensus, faster transaction speed, higher efficiency and lower cost
the alliance chain is a blockchain between the public chain and the private chain, which can realize "partial decentralization"
each node in the chain usually has its corresponding entity or organization; Participants join the network through authorization and form a stakeholder alliance to jointly maintain the operation of the blockchain.

9. This link. If you start the geth client locally, the page will display the following information:
you can see the account balance under balance (ethers). The unit is ether

2. In the command line, geth console. Starts the control terminal of Ethereum
when & quot& gt;& quot; At the prompt, enter Web3. From Wei (ETH. Getbalance (ETH. Coinbase), & quot; ether") After that, press enter to confirm
the account balance will be displayed. The unit is ether.

10. The professional casing manufacturers proce and process casings according to API Spec 51988 and SY / t6194-96
there are 10 grades of steel procts: H40, J55, K55, N80, C75, L80, C90, C95, P110 and q125
proction range: oil casing
4-1 / 2 & quot
to
20 & quot
(usually seamless pipe)
button type: BTC, LTC, STC
for N80 casing, the manufacturer's proction length is R-1 (4.88-7.62m), R-2 (7.62-10.36m) and R-3 (10.36m-longer)
the surface defects of unqualified N80 casing include fish scale fold, slag inclusion fold and slag pit. When choosing the cooperative manufacturer, we should pay more attention to the time and place of the manufacturer
through negotiation between the manufacturer and the demander, submerged arc welded straight seam pipe can be used for large diameter casing (diameter greater than 508mm) used to transport natural gas, gas, oil, water and other liquids and gases
in order to rece the cost, improve the safety and prolong the service life of the casing of the demander, the type of pipe end buckle can be selected as long round thread, partial trapezoidal thread, short round thread and special buckle. The Demander shall specify the type of pipe end buckle in the contract when selecting< The mechanical properties control requirements of N80 raw materials selected by the manufacturer:
in order to make the mechanical properties of N80
grade (36Mn2V)
hot rolled seamless tube meet the API requirements, it is stipulated that the continuous casting slab is heated evenly, the starting rolling temperature is controlled at 1150 ~ 1220
℃, the rolling rhythm is well controlled, and the finishing rolling temperature is 920 ~ 950
℃< N80 oil casing pipe is a kind of seamless steel pipe with high strength and toughness.
the commonly used methods in the world are as follows:
quenching and tempering (including direct quenching and tempering after rolling), normalizing, normalizing +
tempering and tempering after rolling
36Mn2V
is a special steel for N80
grade oil casing, which belongs to microalloyed non quenched and tempered steel. The steel is suitable for processing by temperature control, cooling control and deformation control. The steel pipe can achieve the required performance without quenching and tempering, thus simplifying the proction process and recing the manufacturing cost of steel pipe
the demander's conversion of common units in the inquiry sheet of casing manufacturer: outer diameter 25.4mm = 1in, weight 1.49kg/m
= 1lb / ft, length 1m = 3.28ft.