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我國航空運(yùn)輸?shù)陌l(fā)展歷史和面臨的問題(編輯修改稿)

2025-07-07 00:38 本頁面
 

【文章內(nèi)容簡介】 操作當(dāng)天,主要了是為了減少重新分配的飛機(jī)之間因?yàn)樾D(zhuǎn)松弛所產(chǎn)生中斷干擾的影響。實(shí)施Si和Sj之間的單點(diǎn)交換意味著飛機(jī)被分配給fi的航班會(huì)執(zhí)行fj+1,而分配給fj的航班則將會(huì)執(zhí)行fi+1。三種不同類型的單點(diǎn)交換的機(jī)會(huì),示于圖3。請注意gi, gj, gi→j+1 and gj→i+1分別表示fi 和fi+fj 和 fj+ fi 和fj+1以及 fj 和 fi+1之間的時(shí)間。如圖3中可以看出,實(shí)施類型1和2交換可以創(chuàng)建額外的地面時(shí)間△g。同時(shí)fi和fj還可以預(yù)防連鎖反應(yīng),如果發(fā)生fi,或者fj延遲的情況下。在類型3的情況下,如果要互換的話互換,是不允許任何涉及到的航班增加地面活動(dòng)時(shí)間,但是可以在操作當(dāng)天交換飛機(jī),以滿足維護(hù)要求,交換飛機(jī)使其飛回原來的位置,或者萬一有入站的航班被延遲,可以防止fi + 1和fj+ 1的航班延遲。目標(biāo)值Fi,j(S):是序列Si和Sj之間的單點(diǎn)交換。由方程(4)–(6)定義。如果發(fā)生類型1或類型2互換,F(xiàn)i,j(S)是分別等于pj→i+1或者 pi→j+1。在類型3交換的情況下,F(xiàn)i,j(S)等于最小的pi→j+1 和 pj→i+1。請注意pi→j+1和pj→i+1代表著實(shí)施互換后fj+1和 fi+1準(zhǔn)時(shí)出發(fā)的概率。整個(gè)時(shí)間表的靈活性F(S)等于所有單個(gè)Fi, j(S)值的總和。由公式(7)所定義的。type 1 : gj→i+1gj: Fi,j(S) = pj→i+1type 2 : gi→j+1gi: Fi,j(S) = pi→j+1type 3 : gi= gj= gi→j+1= gj→i+1: Fi,j(S) = min(pi→j+1,pj→i+1第二節(jié)、 本章小結(jié)本章主要是在第二章的基礎(chǔ)上繼續(xù)對航班調(diào)度的模型進(jìn)行優(yōu)化,主要是從時(shí)刻表的穩(wěn)定性和靈活性兩方面入手優(yōu)化調(diào)度模型。本章第一節(jié)主要整體分析了航班時(shí)刻表優(yōu)化所需要的模型,以及對兩個(gè)優(yōu)化目標(biāo)的概念表述。第二章第二節(jié)分別闡述了穩(wěn)定性和靈活性的具體模型并進(jìn)行分析。結(jié) 論我們已經(jīng)呈現(xiàn)了一個(gè)比較完善的基于航班時(shí)刻表優(yōu)化的多目標(biāo)優(yōu)化模型去解決單個(gè)機(jī)場的調(diào)度繁忙以及航班延誤問題。為了方案更實(shí)用可靠,我們在第二章的基礎(chǔ)上又做了拓展,增加了兩個(gè)新的優(yōu)化目標(biāo),對航班調(diào)度進(jìn)行進(jìn)一步的優(yōu)化。雖然這個(gè)報(bào)告的結(jié)果是鼓舞人心的,但是還需要做許多進(jìn)一步的工作。致 謝畢業(yè)設(shè)計(jì)完成了,在這個(gè)過程中我學(xué)到了很多東西。首先我要感謝我的導(dǎo)師黃東賓老師,在我完成論文的過程中,他給予了我很大的幫助和鼓勵(lì)。在構(gòu)思論文思路的時(shí)候,我有很多的問題,比如文獻(xiàn)的選擇,寫作的思路,還有論文的寫作方向等,導(dǎo)師都給予了我悉心的指導(dǎo)和幫助。導(dǎo)師嚴(yán)謹(jǐn)?shù)墓ぷ髯黠L(fēng)、淵博的知識和豐富的實(shí)踐經(jīng)驗(yàn)使我獲益匪淺。參考文獻(xiàn)附 錄一、 英文原文:When One Business Model Isn’t EnoughRamon CasadesusMasanell .Jorge Tarzij225。nTrying to operate more than one business model at a time is devilishly difficult—and frequently cited as a leading cause of strategic failure. Yet situations abound where a pany may wish or need to address several customer segments, using a particular business model for each one. To crowd out petitors or forestall potential disruptors in its current markets, to expand into new markets, to make more efficient use of fixed assets and other resources, or to develop new ine streams may all ideally require distinct business models that operate in tandem.IBM and, for instance, supplemented their reseller distribution model with a directsell model to counteract Dell’s growth in the 1990s. Netflix runs two business models for its DVDbymail and its streamingvideo services. In emerging markets a bank sometimes creates a separate pany to offer credit to low and middleine customers, as Banco SantanderChile has done with Banefe. The forestry pany Celulosa Arauco turns its trees into paper pulp under one business model and into wood panels for highend furniture under another.Nowhere have the perils of running tandem business models been more evident than in the airline industry, where so many fullservice carriers have met with so little success in introducing nofrills offerings to pete with lowcost petitors such as Southwest. Witness what happened to British Airways’ Go Fly, Continental Lite, KLM’s Buzz, and Delta’s Song.That’s what makes the case of LAN Airlines, which successfully operates three business models at once, so remarkable. The Chilean carrier has thrived by integrating a fullservice international passenger airline business model with an aircargo business model while separately operating a nofrills passenger model for domestic flights. In fact, the word “thrived” is too modest: From 1993 to 2010, LAN posted 17% pound annual revenue growth through good times and bad (from $318 million in 1993 to $ billion in 2010), while steadily raising annual net profits from zero to $420 million. LAN’s market capitalization, at $ billion as of March 11, 2011, exceeds that of most of its main global rivals—US Airways ($ billion), American Airlines ($ billion), Korean Air ($ billion), British Airways ($ billion), and UnitedContinental ($ billion). It even tops that of upstart Ryan air ($ billion) and every other Latin American airline. From 1998 to 2010 LAN’s share price, adjusted by dividends and splits, has grown by more than 1,500%.LAN Airlines has succeeded where its rivals have not through a more subtle appreciation of the way different business models relate to one another. Certainly, many business models conflict, as in Netflix’s highprofile case. Others, like the models for digital and film photography, are clear substitutes for each other. No doubt such models should be operated separately, and perhaps, only sequentially. As LAN Airlines’ experience makes clear, however, other business models are plementary. Indeed, they may be so mutually reinforcing that together they turn otherwise unviable possibilities into profitable opportunities. A pany that recognizes which models are substitutes that must be kept separate and which are plements that strengthen each other can build a uniquely sustainable petitive advantage. Let’s look at how LAN has used that insight to its benefit. How LAN’s Three Models InterrelateLAN operates its fullservice international passengercarrier business in much the same way as other global carriers do. It offers frequent flights to major destinations through its own hubs and via alliances with other airlines. It has two classes (coach and business) of amenityfilled service, featuring plimentary hot meals and beverages, multilingual personalentertainment units in coach, and fully flat beds in business class. Likewise, its nofrills domestic operation has essential elements in mon with Southwest’s and Ryan air’s: It is a lowercost, loweroverhead model characterized by fewer amenities, internet ticketing, shorter turnaround times, and a uniform fleet of singleaisle planes from which the kitchens have been removed to increase seating capacity.What sets LAN apart is its cargo business—a premium service like its international passenger operation. It transports salmon from Chile, asparagus from Peru, fresh flowers from Ecuador, and other such perishables to the . and Europe while flying highvaluetoweight merchandise such as puters, mobile phones, and small car par
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