浅析提高制盐蒸发系统有效温差的主要措施

文章从理论上阐明了造成真空制盐蒸发系统有效温差减小的原因，并结合双环盐厂生产实际，分析了提高有效温差的主要措施。     

Nutritive value of rapeseed meal: Effects of individual glucosinolates

In the first of a series of studies on the nutritional value of rapeseed meal, rats were fed diets containing six individual glucosinolates over a period of 29 days. The diets included progoitrin and gluconapin both of which are major components of high glucosinolate rapeseed cultivars. No reduction of feed intake or growth rate was noted and thyroid weights were significantly affected only by the progoitrin diet, which also produced small increases in the weights of the livers and kidneys. There was no depression of plasma thyroid hormone levels.     

Technical note: validation of a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle

The objective of this study was to validate a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle. A total of 42 Holstein cows were tested with access to 24 feed bins and 4 water bins. For the purposes of this validation experiment, we focused our observations on 4 water bins and 13 feed bins. When the cow approached the feed or water bin, an antenna detected the cow's unique passive transponder and lowered the barrier, allowing the cow access to the feed or water. For each visit to the bin, the system recorded the cow number, bin number, initial and final times and weight and calculated the visit duration and intake. Bins were also monitored by direct observation and time-lapse video recording for 2 d per bin, with observations for 4 and 6 h/d for the feed and water bins, respectively. Data from direct observations were compared with the electronic data recorded by the system. Feed disappearance over 24 h was assessed by using an external scale over 3 consecutive 24-h periods, and these values were compared with the sum of intakes across all visits to that bin for the same time periods. The system showed a high specificity (100%) and sensitivity (100 and 99.76% for the feed and water bins, respectively) for cow identification. The duration of the feeding and drinking visits and the feed and water intake per visit, as estimated by the monitoring system, were highly correlated with those obtained by direct observation (R² ≥ 0.99 in all the cases). The comparison of the total feed that disappeared from each bin in 24 h with the sum of the feed cows consumed from that bin during the same period differed by less than 1 kg (29.92 ± 0.90 kg and 29.24 ± 0.90 kg as estimated by manual weighing and by the electronic system, respectively). This difference could be attributed to changes in feed moisture during the 24-h period. In conclusion, this electronic system is a useful tool for monitoring intakes and feeding and drinking behavior of loose-housed cows.     

进料方式对固定流化床流态化行为影响的研究

An experimental installation of cold model simulation was set up to study the bed pressure drop in different regionsof fixed fluidized bed reactor during top feeding and bottom feeding, respectively, at various gas velocities with thefluidization image of solid particles monitored at the same time. By comparing the changes in bed density and operating gasvelocity in different regions of fixed fluidized bed reactor, the influence of top feeding and bottom feeding patterns on fluidizationbehavior could be investigated. The results showed that the bed density in top feeding reactor responded more stablyto the change in gas velocity along with the advantage of working in a wider range of operating gas velocities. Based on thisstudy, it is concluded that existing bottom feeding reactor configurations cannot meet the fluidization requirements; and optimizationof bottom feeding reactor will be needed.     

Competition during the milk-feeding stage influences the development of feeding behavior of pair-housed dairy calves

This study investigated how the feeding behavior of pair-housed calves develops in response to reduced teat and feed place availability. Twenty Holstein bull calves were pair housed and provided with milk replacer (MR) and grain concentrate ad libitum via either (1) 1 teat and feed bucket/pen, such that calves could not feed simultaneously [competitive feeding (CF)] or (2) 2 teats and feed buckets/pen [noncompetitive feeding (NCF)]. The calves were weaned during wk 7 of life by incrementally diluting the MR. Postweaning, all pens were managed identically and offered a complete pelleted diet ad libitum via 2 feed buckets/pen (NCF) in period 1 (wk 8 and 9) and period 3 (wk 12 and 13) and exposed to a competitive challenge with CF in period 2 (wk 10 and 11). Feeding times and competitive interactions were recorded from video for 3 d/wk in wk 2, 4, and 6 and 2 d/wk in wk 8 to 13. Meal criteria were used to calculate daily meal frequency, meal time, and synchronized meal time (the percentage of meal time when calves within the pen were engaged in simultaneous meals). Milk replacer intake was subject to a treatment × week interaction, with calves in CF pens having lower MR intake (wk 2: 8.3 vs. 10.0 L/calf per day for CF vs. NCF), but compensating by increasing intake to a greater extent over time (wk 4–5: 13.3 vs. 11.7 L/d for CF vs. NCF). Corresponding to MR intake, meal frequencies and feeding times evolved differently over this period, increasing in CF pens and decreasing in NCF pens (wk 2: 5.8 vs. 11.1 and wk 4–6: 6.2 vs. 5.1 meals/d for CF vs. NCF). Calves in CF pens also spent less time engaged in synchronized meals (28 vs. 51% of meal time; standard error = 7.1) and displaced each other 5 times more frequently during synchronized eating. Postweaning, calves in previously CF pens maintained 5 times greater displacement frequencies and had fewer overlapping meals than calves in previously NCF pens (34.5 vs. 40.7% of meals, respectively). Postweaning, when calves were all fed noncompetitively (2 buckets/pen in periods 1 and 3), calves previously fed CF had greater intakes in period 3 (4.87 vs. 4.44 kg/d) and a tendency for greater intake in period 1 (2.80 vs. 2.63 kg/d), greater rates of intake in period 3 (87.8 vs. 72.0 g/min) and a tendency for greater rates of intake in period 1 (44.3 vs. 38.9 g/min), and greater meal frequencies in both periods (11.1 vs. 9.9 meals/d). In the competitive challenge period (1 bucket/pen in period 2), intake, rates of intake, and meal frequencies were subject to treatment × week interactions: calves in NCF pens had lower intake and meal frequencies, but increased meal frequency, intake, and rate of intake over time to a greater extent than calves previously in CF pens. These results indicate that calves are able to adapt to moderate competition by increasing meal frequency and that behavioral responses to competition persist postweaning.     

Effects of ad libitum milk intake on dairy calves

Conventional milk feeding for calves (by bucket twice daily at a total of 10% of body weight) was compared with feeding milk for ad libitum consumption from a nipple. Calves were weaned gradually between d 37 and 42 by diluting the milk with water, and body weight and feed consumption were followed until d 63. Calves fed ad libitum drank 89% more milk than calves fed conventionally during the preweaning period, but the ad libitum-fed calves ate only 16% as much calf starter and 17% as much hay. Consumption of starter and hay increased rapidly after weaning, and treatment differences disappeared. Probably as a result of the much higher intake of milk, the ad libitum-fed calves gained 63% more weight than the conventionally fed calves before weaning, resulting in a 10.5-kg weight advantage on d 35. During and immediately after weaning, the rate of weight gain slowed for both treatment groups, but recovered by approximaely d 49. There were no treatment differences in weight gains over the weaning or postweaning periods, and at the end of the experiment on d 63, the calves fed ad libitum maintained an advantage in mean (+/- SEM) body weight (89.07 +/- 2.47 kg vs 81.07 +/- 2.47 kg for the conventionally fed calves). Incidence of diarrhea was low and did not differ between treatment groups. We conclude that ad libitum nipple feeding of milk to dairy calves can allow for increased milk intake and weight gain with no detrimental effects on intake of solid food after weaning.     

Experimental study on the packing of uniform spheres under three-dimensional vibration

Densification of mono-sized sphere packings under three-dimensional (3D) vibration is experimentally studied. The effects of an operational condition, such as vibration amplitude and frequency and feeding method, on packing density are systematically investigated. The results indicate that the dense packings can be achieved by proper control of both vibration amplitude and frequency. The feeding method plays an important role in densification. Higher packing densities can be obtained when the number of particles fed per batch is less than one layer. Packing density decreases with increasing number of particles fed per batch, but keeps constant when the number of particles per batch is larger than three layers. Through the extrapolation on packing density obtained from different sized containers, the maximum packing density is 0.69 for the total feeding method and 0.74 for the batch-wise feeding under the present experimental condition. The formation of ordered structure is discussed based on the particle interlayer diffusion.     

Studies on thrust characteristics of high‐thrust spiral motor

Linear actuators are used in various industrial applications. Conventional linear actuators are a combination of a rotational motor and a ball screw, a hydraulic actuator, or a linear motor. However, these actuators have some demerits. This paper proposes a spiral motor (SPRM) that comprises a helical stator and a helical mover. Owing to its helical structure, the SPRM can be expected to show better performance compared to the conventional linear actuator. A stator and a mover are shown in Figs. 1 and 2, respectively. Helical motion is obtained by this motor and only linear motion is extracted by canceling rotational motion at the end effector. There are two types of SPRMs. One has no ball screw on the output axis, while the other has a ball screw. The former can be used in a direct drive system. However, the gap between the stator and the mover should be controlled because the motor is a magnetic levitation system without a ball screw. Further, the motor requires two three‐phase inverters. The other motor is easy to control because it does not require gap control. However, the motor is inferior to the first motor with regard to position control since the friction in this motor is larger. In this study, a prototype of the SPRM is developed. The prototype constructed is a motor with a ball screw. In this motor, the stator and mover are made of block cells. The stator block is shown in Fig. 3 and the mover block is shown in Fig. 4. The prototype of the SPRM shown in Fig. 5, is developed by using these two blocks. An experiment is conducted to examine the driving of the SPRM. The experimental result is shown in Fig. 6. From this result, it is evident that comprising a helical stator and a helical mover can generate linear motion. Another experiment is conducted for measuring the thrust characteristic of the motor. The result obtained is shown in Fig. 7. From the figure, the thrust constant of the spiral motor, K_f, is obtained as 538.0 N/A. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(2): 58–64, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21168     

自耦变压器供电方式下降低高速铁路钢轨电位的方法及其仿真分析

高速铁路较常速铁路钢轨电位急剧升高,必须采取有效措施降低钢轨电位,以保障人身和设备安全。用Matlab/Simulink建立了牵引供电系统钢轨电位分析模型。在不同技术参数和工况下,将增大泄漏电导、增设钢轨与保护连接线、增设保护线接地等降低钢轨电位的方法应用到仿真模型中研究钢轨电位的分布规律。根据仿真结果分析评估了各种降低钢轨电位方法的效果。