1. Planting preparation: Planting is carried out in mid-March, and the sheds are warmed up 20 days before planting. Anti-insect nets should be set up at the vents and doorways. After the land is frozen, the ploughing should be carried out as soon as possible. The organic fertilizer per mu is about 5000 kg, 15:15: 15 NPK compound fertilizer 80 kg as the base fertilizer, deep turning 30 cm, smashed and leveled, made into sputum to be planted. 2. Plant spacing: plant spacing 40 ~ 45 cm, row spacing 75 ~ 80 cm, 1700 ~ 1900 seedlings per acre. High ridge planting. 3. Slow seedling management: The key to slow seedling management is cold insulation. The temperature is maintained at 25 ° C to 30 ° C during the day and 15 ° C to 18 ° C during the night. In addition, the greenhouse in the slow seedling period is in a relatively closed state. If harmful gases are generated due to the application of unfertilized organic fertilizer, it is necessary to ventilate in time. 4. Before the seedling period until the fruit setting: the temperature during this period should be controlled at 23 °C ~ 25 °C during the day, and the air outlet should be closed at 18 °C ~ 20 °C in the afternoon. The night temperature is maintained at 13 °C ~ 15 °C. Water and fertilizer management is mainly promoted. 5 to 7 days after pouring the water, choose the sunny day to simmer the seedling water, and combine the watering with 10 kg of urea per acre. When the soil surface can be operated, the soil is cut. 5. Management after fruit setting: After the fruit is placed, it should be ventilated. When the temperature of the shed rises to 25 °C, the ventilation will start. The temperature of the shed will be 23 °C ~ 25 °C, about 20 °C in the afternoon, and 15 °C ~ 18 °C in the night. The relative humidity is maintained at 50% to 60%. Controlling temperature and humidity can effectively prevent the occurrence of diseases. When the first ear fruit reaches a diameter of about 4 cm, the fruit water is poured once, and the 15:15:15 NPK compound fertilizer is applied 25-30 kg per mu, and the water is poured in 8 days in April, 6 days after May. Pour 1 water. Each time the fruit is harvested, a 15:15:15 fluorophosphorus potassium compound fertilizer is applied for 25 to 30 kg. Disclaimer: Some articles on this website are transferred from the Internet. If legal rights of third parties are involved, please inform this website. phone
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The pressure of the gas
piston through the connecting rod to the crankshaft, realize the change from
heat energy to mechanical energy.
The work condition is very bad, and the
temperature of 1400-1800 DEG C, and pressure
Up to 13MPa above the gas
contact, greatly alternating thermal stress and mechanical stress.
And by the
serious corrosion of gas, and under the condition of boundary lubrication and
cylinder wall friction and strong impact 1 times.
The piston in high
temperature, high pressure, strong corrosive gas contact so that it has enough
strength and hardness,
Heat resistance and good thermal resistance, high
fatigue strength and corrosion resistance. For high speed diesel Engine Piston
also requires light as far as possible.
In order to reduce the inertia
force.
Marine piston large low speed diesel engine of the crosshead is
usually combined.
The heat treatment process by normalizing and annealing,
and iron pearlite are ferrite organization, has good heat resistance.
Piston
alloy quenched and tempered steel has better heat resistance and corrosion
resistance. The skirt with nodular cast iron annealing treatment, with good wear
resistance.
Management of tomatoes before and after planting