979 resultados para Vehicle routing problem
Resumo:
Rural intersections account for 30% of crashes in rural areas and 6% of all fatal crashes, representing a significant but poorly understood safety problem. Transportation agencies have traditionally implemented countermeasures to address rural intersection crashes but frequently do not understand the dynamic interaction between the driver and roadway and the driver factors leading to these types of crashes. The Second Strategic Highway Research Program (SHRP 2) conducted a large-scale naturalistic driving study (NDS) using instrumented vehicles. The study has provided a significant amount of on-road driving data for a range of drivers. The present study utilizes the SHRP 2 NDS data as well as SHRP 2 Roadway Information Database (RID) data to observe driver behavior at rural intersections first hand using video, vehicle kinematics, and roadway data to determine how roadway, driver, environmental, and vehicle factors interact to affect driver safety at rural intersections. A model of driver braking behavior was developed using a dataset of vehicle activity traces for several rural stop-controlled intersections. The model was developed using the point at which a driver reacts to the upcoming intersection by initiating braking as its dependent variable, with the driver’s age, type and direction of turning movement, and countermeasure presence as independent variables. Countermeasures such as on-pavement signing and overhead flashing beacons were found to increase the braking point distance, a finding that provides insight into the countermeasures’ effect on safety at rural intersections. The results of this model can lead to better roadway design, more informed selection of traffic control and countermeasures, and targeted information that can inform policy decisions. Additionally, a model of gap acceptance was attempted but was ultimately not developed due to the small size of the dataset. However, a protocol for data reduction for a gap acceptance model was determined. This protocol can be utilized in future studies to develop a gap acceptance model that would provide additional insight into the roadway, vehicle, environmental, and driver factors that play a role in whether a driver accepts or rejects a gap.
Resumo:
This report provides recommendations for the state of Iowa over the next five years in regards to automated vehicle policy development. These administrative, planning, legal, and community strategy recommendations for government agencies include: • Encouraging automation by preparing government agencies, infrastructure, leveraging procurement, and advocating for safety mandates • Adjusting long range planning processes by identifying and incorporating a wide range of new automation scenarios • Beginning to analyze and, as necessary, clarify existing law as it apples to automated driving • Auditing existing law • Enforcing existing laws • Ensuring vehicle owners and operators bear the true cost of driving • Embracing flexibility by giving agencies the statutory authority to achieve regulatory goals through different means, allowing them to make small-scale exemptions to statutory regimes and clarifying their enforcement discretion • Thinking locally and preparing publicly • Sharing the steps being taken to promote (as well as to anticipate and regulate) automated driving • Instituting public education about automated vehicle technologies.
Resumo:
The state Departments of Transportation (DOTs) of Iowa, Michigan, and Minnesota formed a consortium to define and develop the next generation highway maintenance vehicle. The Center for Transportation Research and Education of Iowa State University provided staff support to the concept highway maintenance vehicle project, which focused on winter maintenance activities. Phase I of the three-phase project focused on describing the desirable functions of a concept maintenance vehicle. Phase II will include the development, operation, and evaluation of prototype winter maintenance vehicles. Phase III is envisioned to be a comprehensive fleet evaluation of prototype winter maintenance vehicles. This report covers the activities of Phase I. Phase I included conducting a literature review of materials related to winter highway maintenance activities, identifying ideal capabilities of a winter maintenance vehicle, inviting private sector equipment and technology providers to join the project and commit equipment and expertise for Phase II, and determining the specific equipment and technology to be included on the three prototype vehicles for the winter of 1996-1997. Phase I concluded by establishing that assembling the three prototype vehicles would be beneficial to the project and to the three state DOTs.
Resumo:
Provision of left turn lanes is a major problem which lacks an objective approach. Various techniques and procedures in use have been reviewed. Traffic characteristics at typical Iowa intersections have been measured. A rational approach for inclusion of a left turn lane has been developed, based on relating the benefits to the road user to the cost of providing the added turing lane. An analysis of field data gathered under this project indicates that the use of theoretical distribution to describe vehicle headways is not applicable to rural Iowa two lane roads. As an alternate approach the mass of field data gathered were examined using multiple regression techniques to yield equations for predicting stops and delays. The benefit-cost ratio technique is recommended as the criterion for decision making.
Resumo:
Amino-N is preserved because of the scarcity and nutritional importance of protein. Excretion requires its conversion to ammonia, later incorporated into urea. Under conditions of excess dietary energy, the body cannot easily dispose of the excess amino-N against the evolutively adapted schemes that prevent its wastage; thus ammonia and glutamine formation (and urea excretion) are decreased. High lipid (and energy) availability limits the utilisation of glucose, and high glucose spares the production of ammonium from amino acids, limiting the synthesis of glutamine and its utilisation by the intestine and kidney. The amino acid composition of the diet affects the production of ammonium depending on its composition and the individual amino acid catabolic pathways. Surplus amino acids enhance protein synthesis and growth, and the synthesis of non-protein-N-containing compounds. But these outlets are not enough; consequently, less-conventional mechanisms are activated, such as increased synthesis of NO∙ followed by higher nitrite (and nitrate) excretion and changes in the microbiota. There is also a significant production of N(2) gas, through unknown mechanisms. Health consequences of amino-N surplus are difficult to fathom because of the sparse data available, but it can be speculated that the effects may be negative, largely because the fundamental N homeostasis is stretched out of normalcy, forcing the N removal through pathways unprepared for that task. The unreliable results of hyperproteic diets, and part of the dysregulation found in the metabolic syndrome may be an unwanted consequence of this N disposal conflict.
Resumo:
Abstract
Resumo:
Recent trends (1980-2007) in mortality from road traffic crashes in European countries, and, for comparative purposes, in the USA and Japan were reviewed. Data came from the World Health Organisation database. Age-standardised rates, at all ages and at 15-24, 25-64, >=65 years, were computed. Joinpoint regression analyses to evaluate significant changes in trends were performed. In the European Union as a whole rates declined from 20.2 in 1987 to 13.5/100,000 in 2007 in men, and from 6.3 to 3.7/100,000 in women; European Union rates remained lower than USA, but higher than Japanese ones. In 2007, the highest male rates were in Lithuania (36.7/100,000), the Russian Federation (35.2), Ukraine (29.8), and Latvia (28.5), and the lowest ones in the Netherlands (6.2) and Sweden (6.9); the highest female rates were in the Russian Federation (11.3), Lithuania (9.7), Belarus, Latvia, and Ukraine (around 8), and the lowest ones in Switzerland (1.7), the UK, and Nordic countries (around 2). Mortality from motor vehicle crashes declined in northern and western European countries and - though to a lesser extent - in southern European countries, too. Mortality trends were also favourable in the Czech Republic and Poland since the mid 1990's, whereas they were still upwards in Romania and the Russian Federation. No trend was observed in Hungary and Ukraine. Trends were consistent in various age groups considered. Thus, additional urgent and integrated intervention is required to prevent avoidable deaths from motor vehicle crashes, particularly in selected central and eastern European countries.
Resumo:
Peer-reviewed
Resumo:
Peer-reviewed
Resumo:
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.
Resumo:
The continuous wavelet transform is obtained as a maximumentropy solution of the corresponding inverse problem. It is well knownthat although a signal can be reconstructed from its wavelet transform,the expansion is not unique due to the redundancy of continuous wavelets.Hence, the inverse problem has no unique solution. If we want to recognizeone solution as "optimal", then an appropriate decision criterion hasto be adopted. We show here that the continuous wavelet transform is an"optimal" solution in a maximum entropy sense.
Resumo:
The General Assembly Line Balancing Problem with Setups (GALBPS) was recently defined in the literature. It adds sequence-dependent setup time considerations to the classical Simple Assembly Line Balancing Problem (SALBP) as follows: whenever a task is assigned next to another at the same workstation, a setup time must be added to compute the global workstation time, thereby providing the task sequence inside each workstation. This paper proposes over 50 priority-rule-based heuristic procedures to solve GALBPS, many of which are an improvement upon heuristic procedures published to date.
Resumo:
A maximum entropy statistical treatment of an inverse problem concerning frame theory is presented. The problem arises from the fact that a frame is an overcomplete set of vectors that defines a mapping with no unique inverse. Although any vector in the concomitant space can be expressed as a linear combination of frame elements, the coefficients of the expansion are not unique. Frame theory guarantees the existence of a set of coefficients which is “optimal” in a minimum norm sense. We show here that these coefficients are also “optimal” from a maximum entropy viewpoint.
Resumo:
Tämän diplomityön päätavoitteena oli laatia katsastusalan yritykselle liiketoimintasuunnitelma, joka luo perustan yrityksen johtamiselle ja jatkokehittämiselle.Katsastus Kovalainen Oy tarvitsee jatkuvaan käyttöönsä yrityksen toimintaa ohjaavan viitekehyksen. Ensimmäisenä alaongelmana oli selvittää, mitä liiketoiminnaneri osa-alueita liiketoimintasuunnitelma käsittelee? Onnistuneen liiketoimintasuunnitelman yhtenä peruspilarina voidaan pitää sitä, kuinka hyvin se soveltuu kohdeyrityksen käyttöön ja onko sen sisältämä tieto oleellista juuri kohdeyritykselle? Toinen alaongelma ratkaistiin vastaamalla kysymykseen: Millä tavoin yrityksestä ja sen toimintaympäristöstä kyetään erottamaan juuri se oleellisin tieto liiketoimintasuunnitelman luomiseksi? Kolmanneksi alaongelmaksi muodostui kysymys siitä, kuinka liiketoimintasuunnitelman viitekehys ja empiirinen tieto yhdistetään toimivaksi kokonaisuudeksi, jota yritys voi hyödyntää. Työn teoriaosuus on tehty kirjallisuustutkimuksena ja siinä esitellään liiketoimintasuunnitelmaan kuuluvat osa-alueet teorian näkökulmasta. Empiirisen osuuden tiedot on kerätty pääasiassa haastatteluiden avulla. Empiiristä aineistoa on kerätty myös käyttämällä hyväksi jo olemassa olevaa dokumentoitua tietoa yrityksestä, kuten yrityksen tilinpäätös- ja markkinaosuusraportteja. Liiketoimintasuunnitelmaan kuuluva yrityksen sisäinen analyysi auttoi yrityksen johtoa identifioimaan ja priorisoimaan ne toiminnot ja tekijät, jotka eniten vaikuttavat yrityksen menestymiseen ja kilpailukykyyn. Kyseisen analysoinnin avulla huomattiin, että suurimmat puutteet ja kehitystoimenpiteet koskivat Katsastus Kovalaisen markkinointia ja katsastustiloja.Toimintaympäristön analysoinnin tuloksena huomattiin, että Katsastus Kovalaisenmarkkinaosuus on jo 40 prosenttia, jota voidaan pitää sen verran suurena, että tärkeimmäksi tekijäksi tulevaisuudessa katsottiin nykyisen markkinaosuuden säilyttäminen muun muassa pitämällä nykyiset asiakkaat tyytyväisenä.
Resumo:
Verkkoon kytkettävien laitteiden määrä on lisääntynyt viime vuosina, joka luo tarpeen reitittimille ja niiden ominaisuuksille. On muodostunut uusi tarve laitteille, jotka voivat yhdistää erilaisia verkkoja toisiinsa. Tällaisen reitittimen rakentamiseen tarvitaan vakaa alusta. Tällaisella alustalla luodaan mahdollisuus kuormittaa järjestelmää ilman suuria ongelmia. Tällainen alusta on Open Platform, joka on suunniteltu tällaisille toiminnoille ja yhdessä oikeanlaisen verkkoratkaisun kanssa sitä voidaan käyttää sille suunnitellussa ympäristössä. Tämän diplomityön tarkoituksena on arvioida neljää eri reititysohjelmistoa ja kahta eri IP pinoa. Työssä käytetyt testit on suunniteltu arviointia varten ja niiden tarkoituksena on tuoda esille ohjelmistoissa esiintyvät viat ja ongelmat. Kaikki testit ovat samoja kaikille ohjelmille ja tehdään samassa ympäristössä. Testit analysoidaan niiden ajon jälkeen ja niiden tulosten avulla tehdään päätös mitä näistä ohjelmistoista tullaan käyttämään seuraavan sukupolven avoimella alustalla, joka tulee toimimaan Nokian Intelligent Service Nodessa. Tämä verkon laite toimii yhdyskäytävänäerilaisten verkkojen välillä.