張紅亮,楊浩,夏勝利
(北京交通大學(xué)交通運(yùn)輸學(xué)院,北京10044)
不同氣象數(shù)據(jù)精度對(duì)駝峰峰高設(shè)計(jì)的影響0
張紅亮*,楊浩,夏勝利
(北京交通大學(xué)交通運(yùn)輸學(xué)院,北京10044)
氣象數(shù)據(jù)是駝峰峰高設(shè)計(jì)的重要資料,駝峰設(shè)計(jì)規(guī)范使用月均數(shù)據(jù)作為駝峰設(shè)計(jì)計(jì)算溫度、風(fēng)速的依據(jù).本文采用日均數(shù)據(jù)對(duì)全路49個(gè)主要編組站駝峰設(shè)計(jì)計(jì)算溫度、風(fēng)速分析發(fā)現(xiàn),日均數(shù)據(jù)下南、北方地區(qū)駝峰設(shè)計(jì)計(jì)算溫度分別較月均數(shù)據(jù)低1.34℃、0.94℃,計(jì)算風(fēng)速分別較月均數(shù)據(jù)高1.29m/s、1.15m/s,增幅達(dá)30%以上.本文從理論上分析了差異產(chǎn)生的原因,并以三間房編組站為例進(jìn)行了實(shí)證.進(jìn)一步從置信概率的角度分析了全路主要編組站不同數(shù)據(jù)精度下駝峰設(shè)計(jì)計(jì)算溫度、風(fēng)速,基于日均數(shù)據(jù)的駝峰設(shè)計(jì)溫度、風(fēng)速與預(yù)期差值最大僅1.83%,基于月均數(shù)據(jù)的風(fēng)速與預(yù)期差值最小達(dá)18.74%.在此基礎(chǔ)上,研究了不同數(shù)據(jù)精度對(duì)峰高設(shè)計(jì)的影響,揭示出采用月均數(shù)據(jù)存在峰高設(shè)計(jì)偏低的問(wèn)題,并提出至少采用日均數(shù)據(jù)的駝峰設(shè)計(jì)氣象資料選用及設(shè)計(jì)規(guī)范修改建議.
鐵路運(yùn)輸;氣象資料;數(shù)據(jù)精度;峰高設(shè)計(jì);置信概率
駝峰是全天候戶(hù)外作業(yè)的編組站調(diào)車(chē)設(shè)備,氣象環(huán)境(主要指氣溫、風(fēng)速)對(duì)駝峰峰高設(shè)計(jì)具有重要影響,鐵路駝峰及調(diào)車(chē)場(chǎng)設(shè)計(jì)規(guī)范(TB10062-99)(以下簡(jiǎn)稱(chēng)規(guī)范)[1,2]對(duì)駝峰設(shè)計(jì)氣象資料的選用做了具體規(guī)定:取駝峰所在地氣象臺(tái)站(或鄰近臺(tái)站)近10年月均氣溫和月均風(fēng)速為總體,采用均值與不同倍數(shù)標(biāo)準(zhǔn)差之差或之和得到駝峰設(shè)計(jì)計(jì)算氣溫和風(fēng)速值.計(jì)算公式可歸納為
其中
式中r為駝峰設(shè)計(jì)計(jì)算氣溫(或風(fēng)速);rˉ為根據(jù)10年月均氣溫(或風(fēng)速)計(jì)算的10年年均氣溫(或風(fēng)速);σr為計(jì)算氣溫(或風(fēng)速)的標(biāo)準(zhǔn)差,“南方地區(qū)”駝峰系數(shù)取1.96(97.5%的置信概率),“北方地區(qū)”駝峰系數(shù)取1.5(93.32%置信概率);對(duì)于氣溫,公式取“-”;對(duì)于風(fēng)速,公式取“+”;xˉij為j年i月的月均氣溫(或風(fēng)速).
自規(guī)范頒布以來(lái),對(duì)駝峰領(lǐng)域的研究主要集中在調(diào)速控制與解編能力等方面[3-5],對(duì)氣象環(huán)境的研究較少.在日均氣溫、風(fēng)速等數(shù)據(jù)可獲取的條件下[6],采用精度較高(即每條數(shù)據(jù)所代表的時(shí)間范圍,范圍越小精度越高)的日均數(shù)據(jù)計(jì)算駝峰設(shè)計(jì)計(jì)算氣溫、風(fēng)速,對(duì)比規(guī)范中月均數(shù)據(jù)計(jì)算結(jié)果,分析兩者之間差異、產(chǎn)生原因及其對(duì)駝峰峰高設(shè)計(jì)的影響具有重要理論與實(shí)際意義.
為體現(xiàn)普遍性,本文選取全路49個(gè)主要編組站所在地氣象臺(tái)站(或相鄰臺(tái)站)近10年的日均氣溫、風(fēng)速(個(gè)別缺失數(shù)據(jù)采用插值法處理)[7],按照規(guī)范中的方法,分別采用日均數(shù)據(jù)和月均數(shù)據(jù)計(jì)算出駝峰設(shè)計(jì)計(jì)算氣溫和風(fēng)速,統(tǒng)計(jì)結(jié)果如表1所示.
表1 49個(gè)編組站不同數(shù)據(jù)精度下的駝峰設(shè)計(jì)計(jì)算氣溫、風(fēng)速統(tǒng)計(jì)表Table 1 Hum p design tem perature and w ind speed statistics of 49marshalling stations with different meteorologicaldata accuracy
從表1可以看出,基于日均氣溫計(jì)算出的駝峰設(shè)計(jì)計(jì)算溫度較月均氣溫低.其中,“南方地區(qū)”差值相對(duì)較大,為-1.34℃,“北方地區(qū)”差值相對(duì)較小,為-0.94℃.基于日均風(fēng)速計(jì)算出的駝峰設(shè)計(jì)計(jì)算風(fēng)速較月均風(fēng)速大,且差值明顯.其中,“南方地區(qū)”差值較大,達(dá)到1.29m/s,比例達(dá)55.7%;“北方地區(qū)”差值相對(duì)較小,為1.15m/s,比例為37.5%.從以上結(jié)果可以看出,不同數(shù)據(jù)精度下的駝峰設(shè)計(jì)計(jì)算氣溫、風(fēng)速均存在一定差異,其中,計(jì)算風(fēng)速差值占比較大.
3.1 理論分析
從式(1)可以看出,不同數(shù)據(jù)精度計(jì)算結(jié)果差異主要在于rˉ和σr.其中,rˉ為10年數(shù)據(jù)均值,采用月均數(shù)據(jù)和日均數(shù)據(jù)的差異主要在于各月份天數(shù)不同而造成權(quán)重的微小差異,對(duì)計(jì)算結(jié)果影響不大.
對(duì)于標(biāo)準(zhǔn)差σr,不同數(shù)據(jù)精度的計(jì)算方法分別為
設(shè)各月份天數(shù)差別不大,取平均天數(shù)30天,則
式(3)、式(4)可簡(jiǎn)化為
對(duì)σrm、σrd平方后求差得
由(a-b)2≥0可以推導(dǎo)出2ab≤a2+b2,由于日均數(shù)據(jù)存在波動(dòng),必然存在a≠b的情況.根據(jù)式(5)中α、β關(guān)系,對(duì)式(9)的被減數(shù)進(jìn)行放大有
即σrd>σrm
式中σrm、σrd分別為采用月均數(shù)據(jù)和日均數(shù)據(jù)計(jì)算的標(biāo)準(zhǔn)差.
從以上推導(dǎo)可以看出,采用日均數(shù)據(jù)計(jì)算的標(biāo)準(zhǔn)差大于月均數(shù)據(jù)標(biāo)準(zhǔn)差具有理論依據(jù),且數(shù)據(jù)精度越高,標(biāo)準(zhǔn)差越大.
3.2 算例分析
以規(guī)范條文說(shuō)明中三間房編組站所在地齊齊哈爾市氣象數(shù)據(jù)為例,分別采用日均數(shù)據(jù)和月均數(shù)據(jù)計(jì)算出齊齊哈爾市近10年氣溫、風(fēng)速均值,標(biāo)準(zhǔn)差,進(jìn)而計(jì)算出駝峰設(shè)計(jì)計(jì)算氣溫、風(fēng)速及其置信概率,結(jié)果如表2所示.
表2 三間房編組站不同氣象數(shù)據(jù)精度計(jì)算結(jié)果Table 2 Hump design temperature and w ind speed of San Jianfangmarshalling stations with different meteorologicaldata accuracy
分別以5℃、1m/s為步長(zhǎng)統(tǒng)計(jì)出齊齊哈爾市氣溫、風(fēng)速的頻數(shù)分布,繪制出各溫度、風(fēng)速值的頻率曲線(xiàn),標(biāo)出不同氣象數(shù)據(jù)精度下駝峰設(shè)計(jì)計(jì)算氣溫、風(fēng)速覆蓋范圍示意圖分別如圖1、圖2所示(日均數(shù)據(jù)為實(shí)線(xiàn),月均數(shù)據(jù)為虛線(xiàn)).
從表2及圖1、圖2可以看出,采用日均數(shù)據(jù)與月均數(shù)據(jù)計(jì)算出的三間房編組站駝峰設(shè)計(jì)計(jì)算氣溫、風(fēng)速均值差異較小,差值分別為0.08、0.00;采用日均數(shù)據(jù)計(jì)算出的氣溫、風(fēng)速標(biāo)準(zhǔn)差大于月均數(shù)據(jù),差值分別為0.65、1.02,不同數(shù)據(jù)精度的均值、標(biāo)準(zhǔn)差差異與理論分析一致.由日均數(shù)據(jù)計(jì)算出的駝峰設(shè)計(jì)氣溫低于月均數(shù)據(jù),設(shè)計(jì)風(fēng)速大于月均數(shù)據(jù).從置信概率水平看,采用日均數(shù)據(jù)計(jì)算出的駝峰設(shè)計(jì)氣溫、風(fēng)速接近預(yù)期,采用月均數(shù)據(jù)的計(jì)算結(jié)果置信概率差別較大,尤其是設(shè)計(jì)風(fēng)速,差值達(dá)18.73%.
圖1 日均氣溫與月均氣溫覆蓋范圍對(duì)比圖Fig.1 Temperature coverage between daily data and monthly data
圖2 日均風(fēng)速與月均風(fēng)速覆蓋范圍對(duì)比圖Fig.2 Wind speed coverage between daily data and monthly data
為驗(yàn)證分析的正確性,分別基于日均數(shù)據(jù)和月均數(shù)據(jù)計(jì)算出全路49個(gè)主要編組站日均數(shù)據(jù)和月均數(shù)據(jù)下駝峰設(shè)計(jì)計(jì)算溫度和風(fēng)速與預(yù)期置信概率差異情況,統(tǒng)計(jì)結(jié)果如表3所示.
表3 主要編組站不同數(shù)據(jù)精度與預(yù)期置信概率差異統(tǒng)計(jì)表Table 3 Confidence probability statistics ofmain marshalling stations with differentdata accuracy
從表3可以看出,與三間房編組站情況類(lèi)似,基于日均數(shù)據(jù)的駝峰設(shè)計(jì)計(jì)算溫度和風(fēng)速與預(yù)期置信概率吻合程度較好,差值較大的南方地區(qū)駝峰設(shè)計(jì)計(jì)算風(fēng)速僅差1.826%;基于月均數(shù)據(jù)的駝峰設(shè)計(jì)計(jì)算溫度和風(fēng)速與預(yù)期置信概率差值相對(duì)較大,其中月均風(fēng)速的差值尤其大,差值較小的北方地區(qū)達(dá)18.743%.
通過(guò)以上理論及算例分析可以看出,數(shù)據(jù)精度越高,計(jì)算結(jié)果越接近預(yù)期水平.建議駝峰設(shè)計(jì)及作業(yè)控制中氣象資料的選用采用較高精度氣象數(shù)據(jù),至少為日均數(shù)據(jù)精度,同時(shí)建議修訂鐵路駝峰及調(diào)車(chē)場(chǎng)設(shè)計(jì)規(guī)范4.1條款相關(guān)內(nèi)容.
4.1 溫度
溫度對(duì)峰高設(shè)計(jì)的影響是通過(guò)對(duì)單位基本阻力的影響而間接實(shí)現(xiàn)的[1],以常見(jiàn)的點(diǎn)連式駝峰調(diào)速控制系統(tǒng)駝峰峰高設(shè)計(jì)為例,假設(shè)大、中、小能力駝峰峰頂至難行線(xiàn)打靶區(qū)末端長(zhǎng)度分別為600m、400m、200m,以月均氣溫計(jì)算出的峰高值為參照,其它條件相同,日均氣溫計(jì)算出的峰高差值如表4所示.
表4 日均氣溫與月均氣溫下不同類(lèi)型駝峰峰高的差值Table 4 Hum p heightdifference between daily tem perature and monthly tem perature
從表4可以看出,無(wú)論南方地區(qū)還是北方地區(qū),基于日均溫度計(jì)算出的駝峰峰高均較月均溫度高,但由于溫度對(duì)峰高設(shè)計(jì)的影響較小,其最大差值僅0.003m.總體而言,溫度數(shù)據(jù)精度的提高對(duì)峰高的影響較小.
4.2 風(fēng)速
風(fēng)速對(duì)峰高設(shè)計(jì)的影響是通過(guò)對(duì)單位風(fēng)阻力影響而間接實(shí)現(xiàn)的,假設(shè)駝峰溜車(chē)方向與冬季季風(fēng)方向相反,以P70作為駝峰設(shè)計(jì)難行車(chē)型,難行車(chē)質(zhì)量取30t,大、中、小能力駝峰峰頂至難行線(xiàn)打靶區(qū)末端長(zhǎng)度分別為600m、400m、200m,車(chē)輛平均溜放速度分別為4.5m/s、4m/s、3.5m/s,風(fēng)速分別取5m/s、4.5m/s、4m/s,以月均風(fēng)速計(jì)算結(jié)果為參照,其它條件相同,日均風(fēng)速計(jì)算出的峰高差值如表5所示.
表5 日均風(fēng)速與月均風(fēng)速下不同類(lèi)型駝峰峰高差值Table 5 Hum p heightdifference between daily w ind speed and monthly w ind speed
從表5可以看出,無(wú)論南方地區(qū)還是北方地區(qū),風(fēng)速數(shù)據(jù)精度的提高對(duì)駝峰峰高的影響十分顯著.其中,南方地區(qū)駝峰在風(fēng)速數(shù)據(jù)精度提高后峰高增幅均較北方對(duì)應(yīng)類(lèi)型駝峰高;從不同類(lèi)型駝峰增幅看,由大到小依次為大型、中型、小型;從風(fēng)速大小看,風(fēng)速越大,峰高影響幅度越大,風(fēng)速達(dá)到5.0m/s時(shí),影響程度已接近峰高的10%.從表5計(jì)算結(jié)果看,過(guò)去以月均數(shù)據(jù)作為駝峰設(shè)計(jì)氣象資料的選用依據(jù)普遍存在峰高設(shè)計(jì)不足的問(wèn)題.
規(guī)范采用月均數(shù)據(jù)作為駝峰設(shè)計(jì)氣象資料收集與選用的依據(jù),本文基于日均數(shù)據(jù)對(duì)駝峰設(shè)計(jì)氣象資料的選用進(jìn)行了重新計(jì)算,針對(duì)計(jì)算結(jié)果差異,從理論及實(shí)際兩方面分析了產(chǎn)生的原因,進(jìn)而研究了不同氣象數(shù)據(jù)精度對(duì)駝峰峰高設(shè)計(jì)的影響.
(1)基于日均數(shù)據(jù)的駝峰設(shè)計(jì)計(jì)算氣溫較月均數(shù)據(jù)低,南、北方駝峰分別低1.34℃和0.94℃;基于日均數(shù)據(jù)的駝峰設(shè)計(jì)計(jì)算風(fēng)速較月均風(fēng)速高,南、北方駝峰分別高1.29m/s、1.15m/s,增幅分別為55.7%、37.5%.
(2)從理論上分析,對(duì)于均值差異,采用月均數(shù)據(jù)計(jì)算存在不同月份天數(shù)不同而導(dǎo)致的權(quán)重微小差異;對(duì)于標(biāo)準(zhǔn)差,論文從理論上證明了日均數(shù)據(jù)下的標(biāo)準(zhǔn)差大于月均數(shù)據(jù)下的標(biāo)準(zhǔn)差.
(3)從置信概率的角度分析,基于日均數(shù)據(jù)的駝峰設(shè)計(jì)計(jì)算溫度置信概率與預(yù)期差值較小,南、北方駝峰差值均在1%以?xún)?nèi),計(jì)算風(fēng)速置信概率與預(yù)期差值不足2%;基于月均數(shù)據(jù)的駝峰設(shè)計(jì)計(jì)算溫度差值不足3%,但計(jì)算風(fēng)速置信概率與預(yù)期差值在18%以上.
(4)從對(duì)峰高設(shè)計(jì)影響分析,基于日均溫度的峰高與基于月均溫度的峰高差別不大,最大僅0.003m;但基于日均風(fēng)速的峰高與基于月均風(fēng)速的峰高差別較大,大、中、小型駝峰最大差值分別達(dá)到0.352m、0.234m、0.118m.
(5)以往基于月均數(shù)據(jù)的峰高設(shè)計(jì)普遍存在偏低的問(wèn)題,建議駝峰設(shè)計(jì)中采用至少以日均數(shù)據(jù)作為氣象資料的選用依據(jù),并修訂鐵路駝峰及調(diào)車(chē)場(chǎng)設(shè)計(jì)規(guī)范4.1中相關(guān)條款,避免產(chǎn)生較大誤差.
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Effect of M eteorological Data Accu racy on Hum p Height Design
ZHANG Hong-liang,YANG Hao,XIA Sheng-li
(Schoolof Traffic and Transportation,Beijing Jiaotong University,Beijing 100044,China)
Themeteorological data is very important in hump designwork.In the code for design on hump andmarshalling yard of railway,monthlymeteorological data is used for hump design temperature and w ind speed calculation.In this paper,dailymeteorological data is used in 49 humps’design temperature and w ind speed calculation.The result shows that the temperature with daily meteorological data is 1.34℃,0.94℃lower than monthly meteorological data in south and north area,and the w ind speed is 1.29m/s,1.15m/s higher thanmonthlymeteorological data and the amplification ismore than 30%.Then,the paper analyzes the reason in theory and verified with the meteorological data of San Jianfang marshalling station. Confidence probability analyzing shows that the confidence probability of hump design w ind speed and temperature with daily meteorological data is almost the same with expected,with only 1.826%of the maximum difference,but the hump design w ind speed with monthly meteorological data is large,with 18.743%of minimum difference.Then,the impact on hump height design is studied with daily meteorological data and monthly meteorological data,and the problem that the hump height is lower than expected withmonthlymeteorologicaldata is revealed.At last,the suggestions thatdailymeteorological data should be used in hump design w ind speed and temperature calculation at least,and the code for design on hump andmarshalling yard of railway should be revised is proposed.
railway transportation;meteorological data;data accuracy;hump height design;confidence probability
1009-6744(2015)03-0185-05
U291.4+3
A
2014-12-30
2015-03-10錄用日期:2015-04-15
中央高?;究蒲袠I(yè)務(wù)費(fèi)專(zhuān)項(xiàng)資金資助(2012JBM071,2011JBM247).
張紅亮(1981-),男,河南內(nèi)黃人,講師,博士.*通信作者:HLZhang@bjtu.edu.cn