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Temperature in the creep area for piglets will decrease from birth to weaning. To reduce the consumption of electricity and meet the temperature requirement of piglets from birth to weaning, an experiment of variable power heating system of heat lamp compared with constant power heating system of heat lamp was conducted in a scaled pig farm in Northern China. Two units of farrowing room (one unit with 23 farrowing sows and 25 heat lamps of 250 W) in the pig farm were chosen for this study, except for heat lamps, hot water floor heating was provided for piglets. An automatic control system which was composed of ATS (air temperature sensor) and SCM (single chip microcomputer with PID (proportional, integral and derivative) control) and SCR (silicon controlled rectifiers) was used in the test unit and constant power heating system was used in the control unit. The temperature automatic control system can bear 10 000 W. In the test unit, temperature of 30.0 ℃ was set from piglets birth to the age of 7 days, and then reduce temperature by 2.0 ℃ every week till 21 days after birth. In the control unit, heat lamp was with constant power to heat piglets creep areas. Electricity consumption used in the test unit and control unit was recorded by two ammeters, respectively. Behaviors and temperatures in creep area of piglets were recorded and analyzed. Piglets performance was also recorded and analyzed. It was shown that during the first week after birth, both of the heat lamps in the test unit and in the control unit maintain full power operation, the average temperature right below the heat lamp (0.3 m high from the floor) was 27.4 ℃; during the second week, the average temperature right below the heat lamp for the test unit and the control unit were 27.2 and 27.5 ℃, respectively; during the third week, the average temperature right below the heat lamp for the test unit and control unit were 26.8 and 27.4 ℃, respectively. Floor temperature right below the test unit and control unit were 29.5-31.0 and 31.0-30.6 ℃, respectively. In brief, from birth to 21 days, floor temperature right below the heat lamp, side below the lamp and the slatted floor were 29.5-31.0, 28.9-29.5 and 22.9-23.0 ℃, respectively. Lying rates in different areas of right below the heat lamp, side below the lamp and the slatted floor were 40.7%-66.5%, 14.4%-33.4% and 0.9%-8.7%, respectively. Rates of survival of piglets (28 days weaning) in the test unit and control unit were 95.8% and 93.8%, respectively. Average daily gain of piglets (28 days weaning) in the test unit and control unit were 0.198 and 0.193 kg/(head·d), respectively. Using this kind of variable power heating system, the farrowing room can save 1.8 kW·h per lamp per day from 8 days to 14 days after piglets birth, and 2.7 kW·h per lamp per day from 15 days to 21 days after piglets birth. The energy consumption can be saved by 25.4% each batch of production based on 21 days weaning. On condition of electricity price of 0.5215 yuan/(kW·h), 25 heat lamps with 250 W in one farrowing unit and investment of one set of equipment of temperature automatic control with 2 980 yuan, payback period will be 2 a. The temperature automatic control system of heat lamp can not only save energy but also can improve piglets performance. [ABSTRACT FROM AUTHOR]

Temperature in the creep area for piglets will decrease from birth to weaning. To reduce the consumption of electricity and meet the temperature requirement of piglets from birth to weaning, an experiment of variable power heating system of heat lamp compared with constant power heating system of heat lamp was conducted in a scaled pig farm in Northern China. Two units of farrowing room (one unit with 23 farrowing sows and 25 heat lamps of 250 W) in the pig farm were chosen for this study, except for heat lamps, hot water floor heating was provided for piglets. An automatic control system which was composed of ATS (air temperature sensor) and SCM (single chip microcomputer with PID (proportional, integral and derivative) control) and SCR (silicon controlled rectifiers) was used in the test unit and constant power heating system was used in the control unit. The temperature automatic control system can bear 10 000 W. In the test unit, temperature of 30.0 was set from piglets birth to the age of 7 °C days, and then reduce temperature by 2.0 °C every week till 21 days after birth. In the control unit, heat lamp was with constant power to heat piglets creep areas. Electricity consumption used in the test unit and control unit was recorded by two ammeters, respectively. Behaviors and temperatures in creep area of piglets were recorded and analyzed. Piglets performance was also recorded and analyzed. It was shown that during the first week after birth, both of the heat lamps in the test unit and in the control unit maintain full power operation, the average temperature right below the heat lamp (0.3 m high from the floor) was 27.4 °C; during the second week, the average temperature right below the heat lamp for the test unit and the control unit were 27.2 and 27.5 °C, respectively; during the third week, the average temperature right below the heat lamp for the test unit and control unit were 26.8 and 27.4 °C, respectively. Floor temperature right below the test unit and control unit were 29.5-31.0 and 31.0-30.6 °C, respectively. In brief, from birth to 21 days, floor temperature right below the heat lamp, side below the lamp and the slatted floor were 29.5-31.0, 28.9-29.5 and 22.9-23.0 °C, respectively. Lying rates in different areas of right below the heat lamp, side below the lamp and the slatted floor were 40.7%-66.5%, 14.4%-33.4% and 0.9%-8.7%, respectively. Rates of survival of piglets (28 days weaning) in the test unit and control unit were 95.8% and 93.8%, respectively. Average daily gain of piglets (28 days weaning) in the test unit and control unit were 0.198 and 0.193 kg/(head·d), respectively. Using this kind of variable power heating system, the farrowing room can save 1.8 kW·h per lamp per day from 8 days to 14 days after piglets birth, and 2.7 kW·h per lamp per day from 15 days to 21 days after piglets birth. The energy consumption can be saved by 25.4% each batch of production based on 21 days weaning. On condition of electricity price of 0.5215 yuan/(kW·h), 25 heat lamps with 250 W in one farrowing unit and investment of one set of equipment of temperature automatic control with 2 980 yuan, payback period will be 2 a. The temperature automatic control system of heat lamp can not only save energy but also can improve piglets performance. [ABSTRACT FROM AUTHOR]

In the foundation construction of large tidal current power station, the truss hanger system is designed to solve the problem that the weight of crane is large and the lifting capacity of cranes is insufficient. The design process of the truss hanger system is discussed. The finite element calculation of the truss hanger system is carried out. The stress test is carried out during the foundation construction. The result of finite element calculation and stress test in the process of foundation construction show that it is feasible and rational to adopt truss hanger system when the lifting system can be designed with small weight. [ABSTRACT FROM AUTHOR]

By means of the compression of spring to take the place of air pressure, the ETFE foil spring cushion structure system needs no air supply and control equipments, no running energy compared with the traditional air cushion structure. In this paper, the structural behavior of the ETFE foil spring cushion structure consisting of two spring units is studied through numerical analysis and model experiment. Though numerical analysis, the shape of cushion can be determined by the ratio of initial membrane stress to compression of spring. The stiffness of spring has little influence on the membrane stress, but the displacement of membrane surface decreases and the change of compression of spring increases when the stiffness of spring becomes larger in the case of wind or snow load. The ratio of rise to span has also little influence on the membrane stress, but smaller ratio leads to larger displacement. In the model experiment, the membrane surface is easily formed by means of adjusting the compression of spring. In loading test, the spring system worked well and the membrane surface was tensioned continuously by it. The experimental results agreed with those from numerical analysis. [ABSTRACT FROM AUTHOR]