Barge: a ship driven by a motorboat, which has no power propulsion and self-propelled ability. Mainly used for passenger and cargo transportation. Barges can be towed by tugboats or propelled by pushers alone or in groups. It is characterized by simple equipment, shallow draft and large cargo capacity. Barges are generally non-motorized boats, which form a barge fleet with tugboats or pushers. They can sail in narrow waterways and shallow waterways and can be grouped at any time according to the requirements of cargo transportation, which is suitable for cargo transportation between inland ports. Some barges with propulsion devices are called motor barges. The motorized barge has a certain self-propelled capability. There are many kinds of barges. According to the purpose, there are mainly passenger barges and cargo barges. Passenger barges are designed for transporting passengers, with living facilities, and are generally used for passenger transport in small rivers. Cargo barge is used to carry goods, which can be divided into dry cargo barge, ore barge, coal barge and oil barge. Cargo barges are generally not equipped with lifting equipment, and the goods are loaded and unloaded by the loading and unloading machinery on the dock. Cargo barges can also be used to transfer goods at ports. According to the structure of cargo barge, there is a hatch barge with several cargo ports; There is only one cargo hold, and the open barge above the cargo hold is fully open; Deck barge without cargo hold, where goods are stacked on the deck, and there are cargo baffles around the deck; Half-cabin barge, goods are piled on the deck, and there are hatch coamings around the deck; The deck is equipped with closed containers such as tanks for transporting liquid goods such as oil and liquefied gas. According to materials, there are steel barges, wooden barges and cement barges. According to ship types, there are mainly ordinary barges and segmented barges. The fore and aft of ordinary barges are inclined and streamlined, equipped with anchors and rudders. The two ends of the segmented barge are box-shaped (full segmented barge), or one end is inclined and the other end is box-shaped (semi-segmented barge). The ancient ship-to-ship (also called two ships) in China can be regarded as the embryonic form of modern semi-segmented barge fleet. It consists of two ships of the same length. The bow end of the front section is inclined and the tail end is square box, while the bow end of the rear section is square box and the tail end is inclined. One end of the square boxes of the two ships is opposite and connected by cables. The rudder is mounted on the rear boat. Modern segmented barges generally have no rudder, American segmented barges have no anchors, and China and some western European countries have anchors. The sectional barge has simple structure, convenient construction and low cost. Using segmented barge to form a fleet can reduce navigation resistance and improve cargo carrying capacity, so segmented barge is widely used. There are three kinds of segmented barges commonly used in the United States, and their load capacity and scale are determined according to the standard scale of inland waterway. Arbitrage: buying and selling two different futures contracts at the same time Traders buy contracts that they think are "cheap" and sell those "high-priced" contracts at the same time, benefiting from the changing relationship between the prices of the two contracts. In arbitrage, traders are concerned about the mutual price relationship between contracts, not the absolute price level. Arbitrage can generally be divided into three categories: intertemporal arbitrage, cross-market arbitrage and cross-commodity arbitrage. Intertemporal arbitrage is one of the most common arbitrage transactions. When the normal spread between different delivery months changes abnormally, it is profitable to hedge the same commodity, which can be divided into two forms: bull spread and bear spread. For example, when the exchange carries out the metal bull spread, it buys the metal contract in the recent delivery month and sells the metal contract in the forward delivery month, hoping that the price increase of the recent contract will exceed the price of the forward contract; Bear market arbitrage is the opposite, that is, selling the recent delivery monthly contract and buying the forward delivery monthly contract, expecting the price drop of the forward contract to be smaller than the recent contract. Cross-market arbitrage is an arbitrage transaction between different exchanges. When the same futures commodity contract is traded in two or more exchanges, there is a certain price difference relationship between commodity contracts due to geographical differences between regions. For example, London Metal Exchange (LME) and Shanghai Futures Exchange (SHFE) both trade cathode copper futures, and the price difference between the two markets will exceed the normal range several times a year, which provides traders with opportunities for cross-market arbitrage. For example, when LME copper price is lower than SHFE, traders can buy LME copper contract and sell SHFE copper contract at the same time, and then hedge and close the trading contract after the price relationship between the two markets returns to normal, and vice versa. When doing cross-market arbitrage, we should pay attention to several factors that affect the spread of each market, such as freight, tariff and exchange rate. Cross-commodity arbitrage refers to trading by using the price difference between two different but related commodities. These two commodities can replace each other or be restricted by the same supply and demand factors. The form of cross-commodity arbitrage is to buy and sell commodity futures contracts with the same delivery month but different varieties at the same time. For example, metals, agricultural products, metals and energy can all carry out arbitrage transactions.

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