939 resultados para nonparametric demand model
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[eng] We analyze the equilibrium of a multi-sector exogenous growth model where the introduction of minimum consumption requirements drives structural change. We show that equilibrium dynamics simultaneously exhibt structural change and balanced growth of aggregate variables as is observed in US when the initial intensity of minimum consumption requirements is sufficiently small. This intensity is measured by the ratio between the aggregate value of the minimum consumption requirements and GDP and, therefore, it is inversely related with the level of economic development. Initially rich economies benefit from an initially low intensity of the minimum consumption requirements and, as a consequence, these economies end up exhibiting balanced growth of aggregate variables, while there is structural change. In contrast, initially poor economies suffer from an initially large intensity of the minimum consumption requirements, which makes the growth of the aggregate variables unbalanced during a very large period. These economies may never exhibit simultaneously balanced growth of aggregate variables and structural change.
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The purpose of this project is to develop an investment analysis model that integrates the capabilities of four types of analysis for use in evaluating interurban transportation system improvements. The project will also explore the use of new data warehousing and mining techniques to design the types of databases required for supporting such a comprehensive transportation model. The project consists of four phases. The first phase, which is documented in this report, involves development of the conceptual foundation for the model. Prior research is reviewed in Chapter 1, which is composed of three major sections providing demand modeling background information for passenger transportation, transportation of freight (manufactured products and supplies), and transportation of natural resources and agricultural commodities. Material from the literature on geographic information systems makes up Chapter 2. Database models for the national and regional economies and for the transportation and logistics network are conceptualized in Chapter 3. Demand forecasting of transportation service requirements is introduced in Chapter 4, with separate sections for passenger transportation, freight transportation, and transportation of natural resources and commodities. Characteristics and capacities of the different modes, modal choices, and route assignments are discussed in Chapter 5. Chapter 6 concludes with a general discussion of the economic impacts and feedback of multimodal transportation activities and facilities.
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In this thesis, I develop analytical models to price the value of supply chain investments under demand uncer¬tainty. This thesis includes three self-contained papers. In the first paper, we investigate the value of lead-time reduction under the risk of sudden and abnormal changes in demand forecasts. We first consider the risk of a complete and permanent loss of demand. We then provide a more general jump-diffusion model, where we add a compound Poisson process to a constant-volatility demand process to explore the impact of sudden changes in demand forecasts on the value of lead-time reduction. We use an Edgeworth series expansion to divide the lead-time cost into that arising from constant instantaneous volatility, and that arising from the risk of jumps. We show that the value of lead-time reduction increases substantially in the intensity and/or the magnitude of jumps. In the second paper, we analyze the value of quantity flexibility in the presence of supply-chain dis- intermediation problems. We use the multiplicative martingale model and the "contracts as reference points" theory to capture both positive and negative effects of quantity flexibility for the downstream level in a supply chain. We show that lead-time reduction reduces both supply-chain disintermediation problems and supply- demand mismatches. We furthermore analyze the impact of the supplier's cost structure on the profitability of quantity-flexibility contracts. When the supplier's initial investment cost is relatively low, supply-chain disin¬termediation risk becomes less important, and hence the contract becomes more profitable for the retailer. We also find that the supply-chain efficiency increases substantially with the supplier's ability to disintermediate the chain when the initial investment cost is relatively high. In the third paper, we investigate the value of dual sourcing for the products with heavy-tailed demand distributions. We apply extreme-value theory and analyze the effects of tail heaviness of demand distribution on the optimal dual-sourcing strategy. We find that the effects of tail heaviness depend on the characteristics of demand and profit parameters. When both the profit margin of the product and the cost differential between the suppliers are relatively high, it is optimal to buffer the mismatch risk by increasing both the inventory level and the responsive capacity as demand uncertainty increases. In that case, however, both the optimal inventory level and the optimal responsive capacity decrease as the tail of demand becomes heavier. When the profit margin of the product is relatively high, and the cost differential between the suppliers is relatively low, it is optimal to buffer the mismatch risk by increasing the responsive capacity and reducing the inventory level as the demand uncertainty increases. In that case, how¬ever, it is optimal to buffer with more inventory and less capacity as the tail of demand becomes heavier. We also show that the optimal responsive capacity is higher for the products with heavier tails when the fill rate is extremely high.
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This paper describes the state of the art of secure ad hoc routing protocols and presents SEDYMO, a mechanism to secure a dynamic multihop ad hoc routing protocol. The proposed solution defeats internal and external attacks usinga trustworthiness model based on a distributed certification authority. Digital signatures and hash chains are used to ensure the correctness of the protocol. The protocol is compared with other alternatives in terms of security strength, energy efficiency and time delay. Both computational and transmission costs are considered and it is shown that the secure protocol overhead is not a critical factor compared to the high network interface cost.
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VALOSADE (Value Added Logistics in Supply and Demand Chains) is the research project of Anita Lukka's VALORE (Value Added Logistics Research) research team inLappeenranta University of Technology. VALOSADE is included in ELO (Ebusiness logistics) technology program of Tekes (Finnish Technology Agency). SMILE (SME-sector, Internet applications and Logistical Efficiency) is one of four subprojects of VALOSADE. SMILE research focuses on case network that is composed of small and medium sized mechanical maintenance service providers and global wood processing customers. Basic principle of SMILE study is communication and ebusiness insupply and demand network. This first phase of research concentrates on creating backgrounds for SMILE study and for ebusiness solutions of maintenance case network. The focus is on general trends of ebusiness in supply chains and networksof different industries; total ebusiness system architecture of company networks; ebusiness strategy of company network; information value chain; different factors, which influence on ebusiness solution of company network; and the correlation between ebusiness and competitive advantage. Literature, interviews and benchmarking were used as research methods in this qualitative case study. Networks and end-to-end supply chains are the organizational structures, which can add value for end customer. Information is one of the key factors in these decentralized structures. Because of decentralization of business, information is produced and used in different companies and in different information systems. Information refinement services are needed to manage information flows in company networksbetween different systems. Furthermore, some new solutions like network information systems are utilised in optimising network performance and in standardizingnetwork common processes. Some cases have however indicated, that utilization of ebusiness in decentralized business model is not always a necessity, but value-add of ICT must be defined case-specifically. In the theory part of report, different ebusiness and architecture models are introduced. These models are compared to empirical case data in research results. The biggest difference between theory and empirical data is that models are mainly developed for large-scale companies - not for SMEs. This is due to that implemented network ebusiness solutions are mainly large company centered. Genuine SME network centred ebusiness models are quite rare, and the study in that area has been few in number. Business relationships between customer and their SME suppliers are nowadays concentrated more on collaborative tactical and strategic initiatives besides transaction based operational initiatives. However, ebusiness systems are further mainly based on exchange of operational transactional data. Collaborative ebusiness solutions are in planning or pilot phase in most case companies. Furthermore, many ebusiness solutions are nowadays between two participants, but network and end-to-end supply chain transparency and information systems are quite rare. Transaction volumes, data formats, the types of exchanged information, information criticality,type and duration of business relationship, internal information systems of partners, processes and operation models (e.g. different ordering models) differ among network companies, and furthermore companies are at different stages on networking and ebusiness readiness. Because of former factors, different customer-supplier combinations in network must utilise totally different ebusiness architectures, technologies, systems and standards.
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VVALOSADE is a research project of professor Anita Lukka's VALORE research team in the Lappeenranta University of Technology. The VALOSADE includes the ELO technology program of Tekes. SMILE is one of four subprojects of the VALOSADE. The SMILE study focuses on the case of the company network that is composed of small and micro-sized mechanical maintenance service providers and forest industry as large-scale customers. The basic principle of the SMILE study is the communication and ebusiness in supply and demand networks. The aim of the study is to develop ebusiness strategy, ebusiness model and e-processes among the SME local service providers, and onthe other hand, between the local service provider network and the forest industry customers in a maintenance and operations service business. A literature review, interviews and benchmarking are used as research methods in this qualitative case study. The first SMILE report, 'Ebusiness between Global Company and Its Local SME Supplier Network', concentrated on creating background for the SMILE study by studying general trends of ebusiness in supply chains and networks of different industries. This second phase of the study concentrates on case network background, such as business relationships, information systems and business objectives; core processes in maintenance and operations service network; development needs in communication among the network participants; and ICT solutions to respond needs in changing environment. In the theory part of the report, different ebusiness models and frameworks are introduced. Those models and frameworks are compared to empirical case data. From that analysis of the empirical data, therecommendations for the development of the network information system are derived. In process industry such as the forest industry, it is crucial to achieve a high level of operational efficiency and reliability, which sets up great requirements for maintenance and operations. Therefore, partnerships or strategic alliances are needed between the network participants. In partnerships and alliances, deep communication is important, and therefore the information systems in the network also are critical. Communication, coordination and collaboration will increase in the case network in the future, because network resources must be optimised to improve competitive capability of the forest industry customers and theefficiency of their service providers. At present, ebusiness systems are not usual in this maintenance network. A network information system among the forest industry customers and their local service providers actually is the only genuinenetwork information system in this total network. However, the utilisation of that system has been quite insignificant. The current system does not add value enough either to the customers or to the local service providers. At present, thenetwork information system is the infomediary that share static information forthe network partners. The network information system should be the transaction intermediary, which integrates internal processes of the network companies; the network information system, which provides common standardised processes for thelocal service providers; and the infomediary, which share static and dynamic information on right time, on right partner, on right costs, on right format and on right quality. This study provides recommendations how to develop this system in the future to add value to the network companies. Ebusiness scenarios, vision, objectives, strategies, application architecture, ebusiness model, core processes and development strategy must be considered when the network information system will be developed in the next development step. The core processes in the case network are demand/capacity management, customer/supplier relationship management, service delivery management, knowledge management and cash flow management. Most benefits from ebusiness solutions come from the electrifying of operational level processes, such as service delivery management and cash flow management.
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In the present research we have set forth a new, simple, Trade-Off model that would allow us to calculate how much debt and, by default, how much equity a company should have, using easily available information and calculating the cost of debt dynamically on the basis of the effect that the capital structure of the company has on the risk of bankruptcy; in an attempt to answer this question. The proposed model has been applied to the companies that make up the Dow Jones Industrial Average (DJIA) in 2007. We have used consolidated financial data from 1996 to 2006, published by Bloomberg. We have used simplex optimization method to find the debt level that maximizes firm value. Then, we compare the estimated debt with real debt of companies using statistical nonparametric Mann-Whitney. The results indicate that 63% of companies do not show a statistically significant difference between the real and the estimated debt.
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Sähkönkulutuksen lyhyen aikavälin ennustamista on tutkittu jo pitkään. Pohjoismaisien sähkömarkkinoiden vapautuminen on vaikuttanut sähkönkulutuksen ennustamiseen. Aluksi työssä perehdyttiin aiheeseen liittyvään kirjallisuuteen. Sähkönkulutuksen käyttäytymistä tutkittiin eri aikoina. Lämpötila tilastojen käyttökelpoisuutta arvioitiin sähkönkulutusennustetta ajatellen. Kulutus ennusteet tehtiin tunneittain ja ennustejaksona käytettiin yhtä viikkoa. Työssä tutkittiin sähkönkulutuksen- ja lämpötiladatan saatavuutta ja laatua Nord Poolin markkina-alueelta. Syötettävien tietojen ominaisuudet vaikuttavat tunnittaiseen sähkönkulutuksen ennustamiseen. Sähkönkulutuksen ennustamista varten mallinnettiin kaksi lähestymistapaa. Testattavina malleina käytettiin regressiomallia ja autoregressiivistä mallia (autoregressive model, ARX). Mallien parametrit estimoitiin pienimmän neliösumman menetelmällä. Tulokset osoittavat että kulutus- ja lämpötiladata on tarkastettava jälkikäteen koska reaaliaikaisen syötetietojen laatu on huonoa. Lämpötila vaikuttaa kulutukseen talvella, mutta se voidaan jättää huomiotta kesäkaudella. Regressiomalli on vakaampi kuin ARX malli. Regressiomallin virhetermi voidaan mallintaa aikasarjamallia hyväksikäyttäen.
Resumo:
[eng] We analyze the equilibrium of a multi-sector exogenous growth model where the introduction of minimum consumption requirements drives structural change. We show that equilibrium dynamics simultaneously exhibt structural change and balanced growth of aggregate variables as is observed in US when the initial intensity of minimum consumption requirements is sufficiently small. This intensity is measured by the ratio between the aggregate value of the minimum consumption requirements and GDP and, therefore, it is inversely related with the level of economic development. Initially rich economies benefit from an initially low intensity of the minimum consumption requirements and, as a consequence, these economies end up exhibiting balanced growth of aggregate variables, while there is structural change. In contrast, initially poor economies suffer from an initially large intensity of the minimum consumption requirements, which makes the growth of the aggregate variables unbalanced during a very large period. These economies may never exhibit simultaneously balanced growth of aggregate variables and structural change.
Resumo:
[eng] We analyze the equilibrium of a multi-sector exogenous growth model where the introduction of minimum consumption requirements drives structural change. We show that equilibrium dynamics simultaneously exhibt structural change and balanced growth of aggregate variables as is observed in US when the initial intensity of minimum consumption requirements is sufficiently small. This intensity is measured by the ratio between the aggregate value of the minimum consumption requirements and GDP and, therefore, it is inversely related with the level of economic development. Initially rich economies benefit from an initially low intensity of the minimum consumption requirements and, as a consequence, these economies end up exhibiting balanced growth of aggregate variables, while there is structural change. In contrast, initially poor economies suffer from an initially large intensity of the minimum consumption requirements, which makes the growth of the aggregate variables unbalanced during a very large period. These economies may never exhibit simultaneously balanced growth of aggregate variables and structural change.
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Uusien paperikoneiden kysyntä on vähentynyt ja jälkimarkkinointipalveluiden, kuten huoltojen ja varaosamyyntien, merkittävyys paperikoneliiketoiminnassa on kasvanut entisestään viime aikoina. Uudentyyppisiä palveluja kilpailuedun lisäämiseksi kehitellään jatkuvasti. Esimerkki tällaisesta palvelusta on sopimusperusteinen varastointipalvelu, jossa osat ovat myyjän varastossa kunnes asiakas ottaa ne käyttöön. Diplomityön tavoite on rakentaa malli varastoinnin kustannuslaskentaan ja laskea sen avulla varastointipalvelun kustannukset. Perinteinen toimitusketju monine varastoineen ei nykykäsityksen mukaan ole enää kustannustehokas. Yhä useammat yritykset kaupan ja teollisuuden aloilla ovat ryhtyneet soveltamaan VMI (Vendor Managed Inventory) teoriaa toimitusketjuissaan. Varastot ovat tällöin keskitettyjä, tiedonkulku toimitusketjun portaiden välillä on nopeaa ja kysyntään pystytään vastaamaan lyhyemmällä viiveellä sen ennakoitavuuden paranemisen takia. Työn tuloksena on toimintolaskentaan pohjautuva kustannuslaskentamalli, jota voidaan hyödyntää myös hinnoittelupäätöksiä tehtäessä. Työssä esitellään mallin soveltaminen eri tapauksiin ja ehdotetaan jatkotoimenpiteitä.
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Diplomityön tavoitteena oli sanomalehtipaperin kysyntään ja tarjontaan vaikuttavien tekijöiden identifiointi ja analysointi. Nämä tekijät käytiin yhteisesti läpi skenaarioiden avulla. Aluksi kuvattiin teollisuuden ala ja esiteltiin tärkeimmät alaa kuvaavat mittarit. Analyysi tehtiin Porterin kilpailuteorian tekijöiden pohjalta. Työssä listattiin yksittäiset tekijät, jotka vaikuttavat sanomalehtipaperin kysyntään ja tarjontaan. Näistä tekijöistä valittiin tärkeimmät ja niiden pohjalta rakennettiin skenaarioita. Skenaariot kuvaavat erilaisia mahdollisia tulevaisuuksia.Kysyntä kuten myös tarjonta on jakautunut epätasaisesti maailmassa. Alueelliset erot ovat hyvinkin merkittäviä. Tästä johtuu laajamittainen kaupankäynti eri alueiden välillä. Käynnissä oleva paperiteollisuuden konsolidoitumisprosessi auttaa vähentämään sanomalehtipaperin hinnan ja tarjonnan heilahtelua. Tämä puolestaan johtuu alan keskittymisestä ja järkevästä kapasiteetin hallinnasta.Diplomityö korostaa sanomalehtipaperin tuottajien vastuuta tarjonnan lisäämisessä. E-median uhkaa tai mahdollisuutta on myös spekuloitu ja kysynnän alueellisen kysynnän kehitystä on analysoitu. Diplomityö antaa ehdotuksia erilaisiksi tulevaisuuden kehitysvaihtoehdoiksi. Sanomalehtipaperin kysyntä tulee kasvamaan maailmanlaajuisesti, tuotanto tulee siirtymään lähemmäksi markkinoita, kaupankäynti Aasiaan tulee kasvamaan ja yrityksen tulevat keskittymään viisaaseen kapasiteetin hallintaan.
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Työn tavoitteena oli luoda malli, jonka avulla voitaisiin ennustaa kartonkituotteiden hinnan ja kysynnän kehitystä. Työssä kerättiin aluksi tietoa kartonkimarkkinoista haastattelujen ja tilastotietojen avulla. Näiden perusteella luotiin malli, joka kuvaa kartonkimarkkinoiden ja -teollisuuden rakennetta. Erityisesti kiinnitettiin huomiota asiakkaiden tilauskäyttäytymiseen, tuotannonohjaukseen sekä hinnan muodostumiseen. Työssä käytettiin ennustemenetelmänä systeemidynamiikkaa. Oleellista oli löytää systeemissä esiintyvät tärkeimmät takaisinkytkennät ja systeemin avainmuuttujat. Kun kaikille mallin muuttujille oli määritetty yhtälöt ja vakioille annettu arvot, voitiin mallia simuloida, ja saada ennusteet halutuille muuttujille. Työssä esitettiin ennusteet kartonkimarkkinoiden tärkeimmille parametreille kahden vuoden päähän. Työssä tarkasteltiin myös, miten muutokset mallin käyttäytymistä säätelevissä muuttujissa vaikuttavat tuloksiin. Jotta pystyttäisiin paremmin selvittämään koko kartonkiteollisuuden dynamiikka, lisätutkimusta tarvittaisiin vielä eri kartonkilajien substituutiomahdollisuuksista ja hintojen riippuvuuksista. Mielenkiintoista olisi myös tietää, miten tuotannon käyttöasteiden muutokset ja hinnan vaihtelut vaikuttavat liiketoiminnan kannattavuuteen valmistajien näkökulmasta.
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Tutkielman tarkoituksena oli mallintaa varastonhallintajärjestelmä, joka olisi sopiva case yritykselle. Tutkimus aloitettiin case yrityksen varastonhallinan nykytilan kartoituksella, jonka jälkeen tutkittiin varastonhallinnan eri osa-alueisiin. Varastonhallinnan osa-alueista käsiteltiin varastotyyppejä, motiiveja, tavoitteita, kysynnän ennustamista sekä erilaisia varastonhallinnan työkaluja. Sen lisäksi tutkittiin erilaisia varaston täydennysmalleja. Teoriaosuudessa käsiteltiin lisäksi kolmea erilaista tietojärjestelmätyyppiä: toiminnanohjausjärjestelmää, sähköisen kaupankäynnin järjestelmää sekä räätälöityä järjestelmää. Tutkimussuunnitelmassa nämä kolme järjestelmää rajattiin vaihtoehdoiksi, joista jokin valittaisiin case yrityksen varastonhallintajärjestelmäksi. Teorian ja nykytilan pohjalta tehtiin viitekehys, jossa esiteltiin varastonhallintajärjestelmän tieto- ja toiminnallisuusominaisuuksia. Nämä ominaisuudet priorisoitiin neljään eri luokkaan ominaisuuden kriittisyyden mukaan. Järjestelmävaihtoehdot arvioitiin viitekehyksen kriteerien mukaisesti, miten helposti ominaisuudet olisivat toteutettavissa eri vaihtoehdoissa. Tulokset laskettiin näiden arviointien perusteella, jonka jälkeen tulosten analysoinnissa huomattiin, että toiminnanohjausjärjestelmä sopisi parhaiten case yrityksen varastonhallintajärjestelmäksi.
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The main objective of the study is to form a framework that provides tools to recognise and classify items whose demand is not smooth but varies highly on size and/or frequency. The framework will then be combined with two other classification methods in order to form a three-dimensional classification model. Forecasting and inventory control of these abnormal demand items is difficult. Therefore another object of this study is to find out which statistical forecasting method is most suitable for forecasting of abnormal demand items. The accuracy of different methods is measured by comparing the forecast to the actual demand. Moreover, the study also aims at finding proper alternatives to the inventory control of abnormal demand items. The study is quantitative and the methodology is a case study. The research methods consist of theory, numerical data, current state analysis and testing of the framework in case company. The results of the study show that the framework makes it possible to recognise and classify the abnormal demand items. It is also noticed that the inventory performance of abnormal demand items differs significantly from the performance of smoothly demanded items. This makes the recognition of abnormal demand items very important.