1、本科畢業論文外文資料翻譯系 別： 專 業： 姓 名： 學 號： 20* 年 03月 10 日外文資料翻譯譯文馬鈴薯播種機的性能評估 大多數馬鈴薯播種機都是通過勺型輸送鏈對馬鈴薯種子進行輸送和投放。當種植精度只停留在一個可接受水平的時候這個過程的容量就相當低。主要的限制因素是：輸送帶的速度以及取薯勺的數量和位置。假設出現種植距離的偏差是因為偏離了統一的種植距離，這主要原因是升運鏈式馬鈴薯播種機的構造造成的.一個理論的模型被建立來確定均勻安置的馬鈴薯的原始偏差，這個模型計算出兩個連續的馬鈴薯觸地的時間間隔。當談到模型的結論時，提出了兩種假設，一種假設和鏈條速度有關，另一種假設和馬鈴薯的形狀有關。為

2、了驗證這兩種假設，特地在實驗室安裝了一個種植機，同時安裝一個高速攝像機來測量兩個連續的馬鈴薯在到達土壤表層時的時間間隔以及馬鈴薯的運動方式。結果顯示：（a）輸送帶的速度越大，播撒的馬鈴薯越均勻；（b）篩選后的馬鈴薯形狀并不能提高播種精度。主要的改進措施是減少導種管底部的開放時間，改進取薯杯的設計以及其相對于導種管的位置。這將允許杯帶在保持較高的播種精度的同時有較大的速度變化空間。介紹說明升運鏈式馬鈴薯種植機（圖一）是當前運用最廣泛的馬鈴薯種植機。每一個取薯勺裝一塊種薯從種子箱輸送到傳送鏈。這條鏈向上運動使得種薯離開種子箱到達上鏈輪，在這一點上，馬鈴薯種塊落在下一個取薯勺的背面，并局限于金屬導種

3、管內.在底部，輸送鏈通過下鏈輪獲得足夠的釋放空間使得種薯落入地溝里。 圖一，杯帶式播種機的主要工作部件：（1）種子箱；（2）輸送鏈；（3）取薯勺；（4）上鏈輪；（5）導種管；（6）護種壁；（7）開溝器；（8）下鏈輪輪；（9）釋放孔；（10）地溝。 株距和播種精確度是評價機械性能的兩個主要參數。高精確度將直接導致高產以及馬鈴薯收獲時的統一分級(mcphee et al, 1996；pavek & thornton, 2003)。在荷蘭的實地測量株距（未發表的數據）變異系數大約為20%。美國和加拿大早期的研究顯示，相對于玉米和甜菜的精密播種，當變異系數高達69%(misener, 1982；ent

4、z & lacroix, 1983；sieczka et al, 1986)時，其播種就精度特別低。輸送速度和播種精度顯示出一種逆相關關系，因此，目前使用的升運鏈式種植機的每條輸送帶上都裝備了兩排取薯勺而不是一排。雙排的取薯勺可以使輸送速度加倍而且不必增加輸送帶的速度。因此在相同的精度上具有更高的性能是可行的。該研究的目的是調查造成勺型帶式種植機精度低的原因，并利用這方面的知識提出建議，并作設計上的修改。例如在輸送帶的速度、取薯杯的形狀和數量上。為了便于理解，建立一個模型去描述馬鈴薯從進入導種管到觸及地面這個時間段內的運動過程，因此馬鈴薯在地溝的運動情況就不在考慮之列。由于物理因素對農業設備的

5、強烈影響(kutzbach, 1989)，通常要將馬鈴薯的形狀考慮進模型中。兩種零假設被提出來了：（1）播種精度和輸送帶速度無關；（2）播種精度和篩選后的種薯形狀（尤其是尺寸）無關。這兩種假設都通過了理論模型以及實驗室論證的測試。材料及方法2.1 播種材料幾種馬鈴薯種子如圣特、阿玲達以及麻佛來都已被用于升運鏈式播種機測試，因為它們有不同的形狀特征。對于種薯的處理和輸送來說，種薯塊莖的形狀無疑是一個很重要的因素。許多形狀特征在結合尺寸測量的過程中都能被區分出來(du & sun, 2004； tao et al, 1995； zdler, 1969)。在荷蘭，馬鈴薯的等級主要是由馬鈴薯的寬度和高

6、度（最大寬度和最小寬度）來決定的。種薯在播種機內部的整個輸送過程中，其長度也是一個不可忽視的因素。形狀因子s的計算基于已經提到的三種尺寸： 此處l是長度，w是寬度，h是高度（單位：mm），且hw001 m時，這種關系是線性的。 ，測量數據；，數學模型的數據； ，延長到r 0 01米； -，線性關系；r2，決定系數。3.2 馬鈴薯的尺寸和形狀 實驗數據由表三給出。顯示固定進料率為每分鐘400個種薯的時間間隔的標準偏差。這些結果與期望值剛好相反，即高的標準偏差將使得形狀因子增加。球狀馬鈴薯的結果尤其令人吃驚：球的標準偏差高過阿玲達馬鈴薯50%以上。時間間隔的正態分布如圖七所示，球和馬鈴薯之間的差異

7、明顯。兩個不同品種的馬鈴薯之間的差異不明顯。 表三 馬鈴薯品種對種植間距的精確度的影響 品種 標準偏差，ms cv, % 阿玲達 8.60 30 麻佛來 9.92 35 高爾夫球 13.24 46 圖七，固定進料率下不同形狀的沉積的馬鈴薯時間間隔的正態分布。球狀馬鈴薯的這種結果是因為球可以以不同的方式在取薯勺背部定位。臨近杯中球的不同定位導致沉積精度降低。杯帶的三維視圖顯示了取薯勺與導種管之間的間隔的形狀，顯然獲得不同大小的開放空間是可行的。圖八，取薯勺呈45度時的效果圖；馬鈴薯在護種壁的位置對其釋放具有決定性影響。阿玲達塊莖種薯在沉積時比麻佛來的精度高。通過對記錄的幀和馬鈴薯的分析，結果表明

8、：阿玲達這種馬鈴薯總是被定位平行于最長的軸線的護種壁。因此，除了形狀因子外，寬度與高度的高比例值也將造成更大的偏差。阿玲達的這個比例是1.09，麻佛來的為1.15。3.3 實驗室對抗模型測試平臺該數學模型預測了不同情況下的流程性能。相對于馬鈴薯，該模型對球模擬了更好的性能，然而實驗測試的結果卻恰然相反。另外實驗室試驗是為了檢查模型的可靠性。在該模型里，兩個馬鈴薯之間的時間間隔被計算出來。起始點出現在馬鈴薯開始經過a點的時刻，終點出現在馬鈴薯到達c點的時刻。通過實驗平臺，從a到c點的馬鈴薯的時間間隔被測出。每個馬鈴薯的長度、寬度和高度也通過測量獲得，同時記錄了馬鈴薯的數量。測量過程中馬鈴薯在取薯

9、杯上的位置是已經確定好的。這個位置和馬鈴薯的尺寸將作為模型的輸入量，測量過程將阿玲達與麻佛來以400個馬鈴薯每分的速率下進行。測量時間間隔的標準偏差如表四所示。測量的標準誤差與模型的標準誤差只是稍稍不同。對這種不同現象的解釋是：（1）模型并沒有把圖八中出現的情況考慮進去；（2）從a點到c點的時間不一致。塊狀馬鈴薯如阿玲達可能從頂部或者最遠距離下落，這將導致種薯到達c點底部的時間增加6ms表四 通過實驗室測量和模型計算出來的開放時間的標準誤差的差異 品種 形狀因子 標準偏差, ms 測量值 計算值 阿玲達 326 8.02 5.22 麻佛來 175 6.96 4.404. 總結這個模擬馬鈴薯從輸

10、送帶開始釋放的運動的數學模型是一個非常有用的證實假設和設計實驗平臺的工具。模型和實驗室的測試都表明：鏈速越高，馬鈴薯在零速度水平沉積得更均勻。這是由于開口足夠大使得馬鈴薯下降得越快，這對馬鈴薯的形狀和種薯在取薯杯上的定位有一定的影響，與鏈條速度的關系也就隨之明確，因此，在保持高的播種精度時，應該提供更多的空間以減小鏈條的速度。建議降低鏈輪的半徑，直至低到技術上的可行度。該研究顯示，播種機的取薯勺升運鏈鏈對播種精度（播種的幅寬）有很大的影響。更規格的形狀（形狀因子低）并不能自動提高播種精度。小球（高爾夫球）在很多情況下沉積的精度低于馬鈴薯，這是由導向的導種管和取薯勺的形狀決定的。因此建議重新設計

11、取薯勺和導種管的形狀，要做到這一點還應該將小鏈輪加以考慮。外文原文assessment of the behaviour of potatoes in a cup-belt planterthe functioning of most potato planters is based on transport and placement of the see potatoes by a cup-belt. the capacity of this process is rather low when planting accuracy has to stay at acceptable lev

12、els. the main limitations are set by the speed of the cup-belt and the number and positioning of the cups. it was hypothesized that the inaccuracy in planting distance, that is the deviation from uniform planting distances, mainly is created by the construction of the cup-belt planter. to determine

13、the origin of the deviations in uniformity of placement of the potatoes atheoretical model was built. the model calculates the time interval between each successive potato touching the ground. referring to the results of the model, two hypotheses were posed, one with respect to the effect of belt sp

14、eed, and one with respect to the inuence of potato shape. a planter unit was installed in a laboratory to test these two hypotheses. a high-speed camera was used to measure the time interval between each successive potato just before they reach the soil surface and to visualize the behaviour of the

15、potato. the results showed that: (a) the higher the speed of the cup-belt, the more uniform is thedeposition of the potatoes; and (b) a more regular potato shape did not result in a higher planting accuracy. major improvements can be achieved by reducing the opening time at the bottom of the duct an

16、d by improving the design of the cups and its position relative to the duct. this will allow more room for changes in the cup-belt speeds while keeping a high planting accuracy. 1. introduction the cup-belt planter (fig. 1) is the most commonly used machine to plant potatoes. the seed potatoes are t

17、ransferred from a hopper to the conveyor belt with cups sized to hold one tuber. this belt moves upwards to lift the potatoes out of the hopper and turns over the upper sheave. at this point, the potatoes fall on the back of the next cup and are confined in a sheet-metal duct. at the bottom, the bel

18、t turns over the roller, creating the opening for dropping the potato into a furrow in the soil. capacity and accuracy of plant spacing are the main parameters of machine performance.high accuracy of plant spacing results in high yield and a uniform sorting of the tubers at harvest (mcphee et al., 1

19、996; pavek & thornton, 2003). field measurements (unpublished data) of planting distance in the netherlands revealed a coefficient of variation (cv) of around 20%. earlier studies in canada and the usa showed even higher cvs of up to 69% (misener, 1982; entz & lacroix, 1983; sieczka et al., 1986), i

20、ndicating that the accuracy is low compared to precision planters for beet or maize. travelling speed and accuracy of planting show an inverse correlation. therefore, the present cup-belt planters are equipped with two parallel rows of cups per belt instead of one. doubling the cup row allows double

21、 the travel speed without increasing the belt speed and thus, a higher capacity at the same accuracy is expected. the objective of this study was to investigate the reasons for the low accuracy of cup-belt planters and to use this knowledge to derive recommendations for design modifications, e.g. in

22、 belt speeds or shape and number of cups. for better understanding, a model was developed, describing the potato movement from the moment the potato enters the duct up to the moment it touches the ground. thus, the behaviour of the potato at the bottom of the soil furrow was not taken into account.

23、as physical properties strongly inuence the efficiency of agricultural equipment (kutzbach, 1989), the shape of the potatoes was also considered in the model. two null hypotheses were formulated: (1) the planting accuracy is not related to the speed of the cup-belt; and (2) the planting accuracy is

24、not related to the dimensions (expressed by a shape factor) of the potatoes. the hypotheses were tested both theoretically with the model and empirically in the laboratory. fig 1. working components of the cup-belt planter: (1) potatoes in hopper; (2) cup-belt; (3) cup; (4) upper sheave; (5) duct; (

25、6) potato on back of cup; (7) furrower; (8) roller; (9) release opening; (10) ground level 2 .materials and methods 2.1. plant material seed potatoes of the cultivars (cv.) sante, arinda and marfona have been used for testing the cup-belt planter, because they show different shape characteristics. t

26、he shape of the potato tuber is an important characteristic for handling and transporting. many shape features, usually combined with size measurements, can be distinguished (du & sun, 2004; tao et al., 1995; zodler,1969).in the netherlands grading of potatoes is mostly done by using the square mesh

27、 size (koning de et al.,1994),which is determined only by the width and height (largest and least breadth) of the potato. for the transport processes inside the planter, the length of the potato is a decisive factor as well. a shape factor s based on all three dimensions was introduced: (1)where/ is

28、 the length, w the width and h the height of the potato in mm, with hwl. as a reference, also spherical golf balls (with about the same density as potatoes), representing a shape factor s of 100 were used. shape characteristics of the potatoes used in this study are given in table 1. 表一 實驗中馬鈴薯及高爾夫球的

29、形狀特征 品種 方形網目尺寸，毫米 形狀因子 圣特 2835 146 阿玲達 3545 362 麻佛來 3545 168 高爾夫球 42.8 1002.2. mathematical model of the process a mathematical model was built to predict planting accuracy and planting capacity of the cup-belt planter. the model took into consideration radius and speed of the roller, the dimensions

30、 and spacing of the cups, their positioning with respect to the duct wall and the height of the planter above the soil surface (fig. 2). it was assumed that the potatoes did not move relative to the cup or rotate during their downward movement. the field speed and cup-belt speed can be set to achiev

31、e the aimed plant spacing. the frequency fpot of potatoes leaving the duct at the bottom is calculated as (2)where v c is the cup-belt speed in m s1and xc is in the distance in m between the cups on the belt. the angular speed of the roller r in rad s1 with radius r r in m is calculated as (3)the ga

32、p in the duct has to b e large enough for a potato to pass and be released .this gap xrelease in m is reached at a certain angle release in rad of a cup passing the roller. this release angle release (fig.2) is calculated as where: rc is the sum in m of the radius of the roller, the thickness of the

33、 belt and the length of the cup; and xclear is the clearance in m between the tip of the cup and the wall of the duct. when the parameters of the potatoes are known, the angle required for releasing a potato can be calculated. apart from its shape and size, the position of the potato on the back of

34、the cup is determinative. therefore, the model distinguishes two positions: (a) minimum required gap, equal to the height of a potato; and (b) maximum required gap equal to the length of a potato. the time trelease in s needed to form a release angle a0 is calculated as calculating trelease for diff

35、erent potatoes and possible positions on the cup yields the deviation from the average time interval between consecutive potatoes.combined with the duration of the free fall and the field speed of the planter, this gives the planting accuracy. when the potato is released, it falls towards the soil s

36、urface. as each potato is released on a unique angular position, it also has a unique height above the soil surface at that moment (fig. 2). a small potato will be released earlier and thus at a higher point than a large one. the model calculates the velocity of the potato just before it hits the so

37、il surface end in m s1 the initial vertical velocity of the potato vo in m s is assumed to equal the vertical component of the track speed of the tip of the cup: the release height yrelease in m is calculated asyrelease=yr-rcsinreleasewhere yr in m is the distance between the centre of the roller (l

38、ine a in fig.2) and the soil surface. the time of free fall tfall in s is calculated withwhere g is the gravitational acceleration(9.8ms-2) and the final velocity vend is calculated aswith vo in ms-1 being the vertical downward speed of the potato at the moment of release.the time for the potato to

39、move from line a to the release point trelease has to be added to t fall. the model calculates the time interval between two consecutive potatoes that may be positioned in different ways on the cups. the largest deviations in intervals will occur when a potato positioned lengthwise is followed by on

40、e positioned heightwise, and vice versa.fig. 2. process simulated by model, simulation starting when the cup crosses line a; release time represents time needed to create an opening sufficiently large for a potato to pass; model also calculates time between release of the potato and the moment it re

41、aches the soil surface (free fall); r c, sum of the radius of the roller, thickness of the belt and length of the cup; xclear, clearance between cup and duct wall; xrelease , release clearance; xrelease release angle ;w,angular speed of roller;line c,ground level,end of simulation.2.3. the laborator

42、y arrangement a standard planter unit (miedema hassia sl 4(6) was modified by replacing part of the bottom end of the sheet metal duct with similarly shaped transparent acrylic material (fig. 3). the cup-belt was driven via the roller (8 in fig. 1), by a variable speed electric motor. the speed was

43、measured with an infrared revolution meter. only one row of cups was observed in this arrangement. a high-speed video camera (speedcam pro, wein- berger ag, dietikon, switzerland) was used to visualise the behaviour of the potatoes in the transparent duct and to measure the time interval between con

44、secutive potatoes. a sheet with a coordinate system was placed behind the opening of the duct, the x axis representing the ground level. time was registered when the midpoint of a potato passed the ground line. standard deviation of the time interval between consecutive potatoes was used as measure

45、for plant spacing accuracy. for the measurements the camera system was set to a recording rate of 1000 frames per second. with an average free fall velocity of 2.5 m s -1,the potato moves approx 2.5 mm between two frames, sufficiently small to allow an accurate placemen registration. the feeding rat

46、es for the test of the effect of the speed of the belt were set at 300, 400 and 500 potatoes min-1(fpot=5,6.7and8.3s-1) corresponding to belt speeds of 0.33,.0.45 and 0.56ms-1. these speeds would be typical for belts with 3, 2 and 1 rows of cups, (cup-belt speed of 0.45 m s -1) was used to assess the effect of the potato shape. for th assessment of a normal distribution of the time intervals, 30 potatoes in five repetitions were used. in the other tests, 20 potatoes in three repetitions were used. 2.4. statistical analysis the hypotheses