2,034 research outputs found
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What Turkey expects from logistics outsourcing ?
Copyright @ 2011 Yasar UniversityThe economies of the world have become increasingly interdependent, and organizations have come under tremendous pressure to maximize productivity and profitability. Creating value through outsourcing has emerged as a popular competitive strategy for firms of all sizes in all types of industries. The aim of this research is to investigate the use of third party logistics in Turkish companies from the users’ perspective to identify the types of logistics services outsourced, problems encountered in outsourcing these services, logistics costs, decision makers in outsourcing logistics activities, and information sources used in the decision-making process. A structured survey was selected as the tool for data collection. The field study involved face-to-face interviews with 204 companies out of top 500 companies ranked in terms of turnover that are registered with industrial associations and chambers of commerce in Turkey. Moreover, a decision support system based on Bayesian Causal Map is proposed for 3PLs in order to assist them in their service proposals for different sectors. This study is a first attempt to reveal and compare the outsourcing perception of the companies in different sectors, to expose the firms’ underlying motives as well as the respective importance of these motives for outsourcing logistics activities in Turkey. The use of Bayesian Causal Map based on the survey results provides an important guide to the 3PL providers to pick a suitable strategy and to prioritize their operational activities in different sectors in such a way to achieve a competitive advantage
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Analyzing competitiveness of automotive industry through cumulative belief degrees
Copyright @ 2012 The European Mathematical SocietyThis study aims to analyze the automotive industry from competitiveness perspective using a novel cumulative belief degrees (CBD) approach. For this purpose, a mathematical model based on CBD is proposed to quantify the relations among the variables in a system. This model is used to analyze the Turkish Automotive Industry through scenario analysis.This research is supported by SEDEFED (Federation of Industrial Associations), REF (TÜSİAD Sabanci University Competitiveness Forum), and OSD (Automotive Manufacturers Association
Optimizing fire station locations for the Istanbul metropolitan municipality
Copyright @ 2013 INFORMSThe Istanbul Metropolitan Municipality (IMM) seeks to determine locations for additional fire stations to build in Istanbul; its objective is to make residences and historic sites reachable by emergency vehicles within five minutes of a fire station’s receipt of a service request. In this paper, we discuss our development of a mathematical model to aid IMM in determining these locations by using data retrieved from its fire incident records. We use a geographic information system to implement the model on Istanbul’s road network, and solve two location models—set-covering and maximal-covering—as what-if scenarios. We discuss 10 scenarios, including the situation that existed when we initiated the project and the scenario that IMM implemented. The scenario implemented increases the city’s fire station coverage from 58.6 percent to 85.9 percent, based on a five-minute response time, with an implementation plan that spans three years
Capacity Bounds and Concatenated Codes Over Segmented Deletion Channels
Cataloged from PDF version of article.We develop an information theoretic characterization
and a practical coding approach for segmented deletion
channels. Compared to channels with independent and identically
distributed (i.i.d.) deletions, where each bit is independently
deleted with an equal probability, the segmentation assumption
imposes certain constraints, i.e., in a block of bits of a certain
length, only a limited number of deletions are allowed to occur.
This channel model has recently been proposed and motivated
by the fact that for practical systems, when a deletion error
occurs, it is more likely that the next one will not appear
very soon. We first argue that such channels are information
stable, hence their channel capacity exists. Then, we introduce
several upper and lower bounds with two different methods in an
attempt to understand the channel capacity behavior. The first
scheme utilizes certain information provided to the transmitter
and/or receiver while the second one explores the asymptotic
behavior of the bounds when the average bit deletion rate is
small. In the second part of the paper, we consider a practical
channel coding approach over a segmented deletion channel.
Specifically, we utilize outer LDPC codes concatenated with inner
marker codes, and develop suitable channel detection algorithms
for this scenario. Different maximum-a-posteriori (MAP) based
channel synchronization algorithms operating at the bit and
symbol levels are introduced, and specific LDPC code designs are
explored. Simulation results clearly indicate the advantages of the
proposed approach. In particular, for the entire range of deletion
probabilities less than unity, our scheme offers a significantly
larger transmission rate compared to the other existing solutions
in the literature
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İstanbul`da itfaiye istasyonu yerlerinin seçimi için yeni bir model - Fire station location selection for Istanbul
This Article is in Turkish and can be accessed from the link below.Özellikle acil hizmetler veren polis, hastane, itfaiye gibi kurumlar için yer seçimi büyük önem taşımaktadır. Uygun bir yer seçimi gerçekleştirilmediği takdirde bunun sonuçları insan hayatını tehlikeye atabilir niteliktedir. İstanbul gibi büyük metropollerde, artan nüfus ve trafik yoğunluğunun yanı sıra bir de metropolün deprem kuşağında olması durumunda, itfaiye araçlarının olay yerine en hızlı şekilde ulaşması hayati önem taşımakta; bu da itfaiye istasyonu yerinin etkin seçimine kritik bir rol yüklemektedir. Bu çalışma; İstanbul Büyükşehir Belediyesi tarafından kararlaştırıldığı gibi, itfaiye teşkilatının her bölgeye en çok beş dakikada erişebilmesi ve kapsama alanının %100 olması hedeflenerek yeni kurulacak olan itfaiye istasyonlarının küme kapsama modeli yardımıyla konumlandırılmasını içermektedir. Bu amaçla bir tamsayı programlama modeli kurulmuş, coğrafi bilgi sistemlerinden elde edilen verilerle model çözülmüş, seçilen yerler için itfaiye kurulması durumunda yangın hizmet düzeyinin değişimi incelenmiştir. - For emergency services such as ambulance systems and fire departments, location selection plays a critical role due to the direct impact of these services on human lives. Timeliness plays a primary role in location selection decision of fire stations for large metropolitan cities such as Istanbul with increasing population with a high level of congestion coupled with an imminent earthquake risk. This study is based on a set-covering model for locating new fire stations, which target to serve each area at most in five minutes and improve their coverage area to 100% for Istanbul Municipality Fire Department. Accordingly, a set-covering model is built and solved using the data retrieved from geographical information systems. Finally the change in service level with proposed fire station locations is investigated and further suggestions are provided
Polarization entangled photon-pair source based on quantum nonlinear photonics and interferometry
We present a versatile, high-brightness, guided-wave source of polarization
entangled photons, emitted at a telecom wavelength. Photon-pairs are generated
using an integrated type-0 nonlinear waveguide, and subsequently prepared in a
polarization entangled state via a stabilized fiber interferometer. We show
that the single photon emission wavelength can be tuned over more than 50 nm,
whereas the single photon spectral bandwidth can be chosen at will over more
than five orders of magnitude (from 25 MHz to 4 THz). Moreover, by performing
entanglement analysis, we demonstrate a high degree of control of the quantum
state via the violation of the Bell inequalities by more than 40 standard
deviations. This makes this scheme suitable for a wide range of quantum optics
experiments, ranging from fundamental research to quantum information
applications. We report on details of the setup, as well as on the
characterization of all included components, previously outlined in F. Kaiser
et al. (2013 Laser Phys. Lett. 10, 045202).Comment: 16 pages, 7 figure
Climate change and growing megacities: hazards and vulnerability
This paper is a review of geophysical and climatic trends associated with extreme weather events and natural hazards, their implications for urban areas and the effects of continued environmental modification due to urban expansion. It discusses how urban design, technological development and societal behaviour can either ameliorate or worsen climate-induced hazards in urban areas. Pressures – ranging from excessive rainfall causing urban flooding to urban temperature extremes driving air pollution – require more attention to understand, model and predict changes in hazards in urban areas. It concludes that involving different techniques for data analysis and system modelling is more appropriate for practical decision-making than a purely reductionist approach. Successfully determining the future environment of megacities will, however, require joint action with societally informed decision makers, grounded in sound scientific achievements
Towards a procedure-optimised steerable catheter for deep-seated neurosurgery
In recent years, steerable needles have attracted significant interest in relation to minimally invasive surgery (MIS). Specifically, the flexible, programmable bevel-tip needle (PBN) concept was successfully demonstrated in vivo in an evaluation of the feasibility of convection-enhanced delivery (CED) for chemotherapeutics within the ovine model with a 2.5 mm PBN prototype. However, further size reductions are necessary for other diagnostic and therapeutic procedures and drug delivery operations involving deep-seated tissue structures. Since PBNs have a complex cross-section geometry, standard production methods, such as extrusion, fail, as the outer diameter is reduced further. This paper presents our first attempt to demonstrate a new manufacturing method for PBNs that employs thermal drawing technology. Experimental characterisation tests were performed for the 2.5 mm PBN and the new 1.3 mm thermally drawn (TD) PBN prototype described here. The results show that thermal drawing presents a significant advantage in miniaturising complex needle structures. However, the steering behaviour was affected due to the choice of material in this first attempt, a limitation which will be addressed in future work
Suppression factors in diffractive photoproduction of dijets
After new publications of H1 data for the diffractive photoproduction of
dijets, which overlap with the earlier published H1 data and the recently
published data of the ZEUS collaboration, have appeared, we have recalculated
the cross sections for this process in next-to-leading order (NLO) of
perturbative QCD to see whether they can be interpreted consistently. The
results of these calculations are compared to the data of both collaborations.
We find that the NLO cross sections disagree with the data, showing that
factorization breaking occurs at that order. If direct and resolved
contributions are both suppressed by the same amount, the global suppression
factor depends on the transverse-energy cut. However, by suppressing only the
resolved contribution, also reasonably good agreement with all the data is
found with a suppression factor independent of the transverse-energy cut.Comment: 28 pages, 11 figures, 3 table
Quaero@H1: An Interface to High-pT HERA Event Data
Distributions from high-pT HERA event data analyzed in a general search for
new physics at H1 have been incorporated into Quaero, an algorithm designed to
automate tests of specific hypotheses with high energy collider data. The use
of Quaero@H1 to search for leptoquarks, R-parity violating supersymmetry, and
excited quarks provides examples to develop intuition for the algorithm's
performance.Comment: Submitted to Eur. Phys. J.
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