5916 research outputs found
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Capacitated strategic assortment planning under explicit demand substitution
No full textBuyers have easier access to a variety of products with the rise of multi-channel distribution strategies and the increase in new product introductions. On the other hand, firms experience greater pressure in offering the correct product variety given that the manufacturing infrastructure often imposes physical and financial constraints in attaining variety. This study examines a firm's optimal assortment planning problem under an exogenous demand model, where each customer has a predetermined preference for each product from a potential set. Proportional demand substitutions are allowed from out-of-assortment products to those available. We show that the problem is NP-complete. We also show that an optimal assortment is composed of some number of the highest margin products, if one product having a higher margin than another implies that the former product has a lower demand rate than the latter. The firm's assortment capacity is fully utilized at the optimum if the customers’ substitution ratio does not exceed a particular threshold. We also introduce several approximate assortment policies that can be easily implemented, and test these policies through extensive numerical analyses. The results reveal that some of the policies can provide less than a 1% profit gap with an optimal solution for a 20-product set. The policy's performance highly depends on the firm's assortment capacity-to-product set size ratio. Moreover, we provide performance bounds for two of these well-performing approximate policies.TÜBİTA
Investigating the impacts of coaching and mentoring through induction on the experienced teachers
No full textSince induction programs are generally implemented for beginning teachers, those designed in response to experienced teachers' pedagogical needs are rare, and their impacts on these teachers are not so widely researched. This chapter reports the process of a one-year comprehensive induction program that is designed for 11 experienced teachers who are newly hired at the English preparation program of a highly competitive English medium university in Turkey and its impacts on the emotions of the participants. The study encompassed the concurrent embedded strategy of mixed methods approach. Data were collected through semi-structured interviews and the positive and negative affect schedule (PANAS-SF). The present study has supported multiple aspects of previous data regarding induction programs for beginning teachers and provided valuable findings supporting the benefits that comprehensive induction programs that provide coaching and mentoring can bring for experienced EFL teachers when they start working in a new institution
Effect regulated projection of robot’s action space for production and prediction of manipulation primitives through learning progress and predictability based exploration
No full textIn this study, we propose an effective action parameter exploration mechanism that enables efficient discovery of robot actions through interacting with objects in a simulated table-top environment. For this, the robot organizes its action parameter space based on the generated effects in the environment and learns forward models for predicting consequences of its actions. Following the Intrinsic Motivation approach, the robot samples the action parameters from the regions that are expected to yield high learning progress (LP). In addition to the LP-based action sampling, our method uses a novel parameter space organization scheme to form regions that naturally correspond to qualitatively different action classes, which might be also called action primitives. The proposed method enabled the robot to discover a number of lateralized movement primitives and to acquire the capability of prediction the consequences of these primitives. Furthermore our results suggest the reasons behind the earlier development of grasp compared to push action in infants. Finally, our findings show some parallels with data from infant development where correspondence between action production and prediction is observed.Bogazici Research Fund ; Japan Science and Technology Agenc
The value of quality grading in remanufacturing under quality level uncertainty
No full textIn remanufacturing, variability in quality levels of available cores (end-of-life products) has an impact on both the process cost and the process time. While previous research suggests that quality grading adds value, there are also concerns raised regarding how reliably the grades can be identified. We argue that uncertainty is inherent to the grading process and investigate the value of grading by taking into account the underlying uncertainty. We develop a robust optimisation model for remanufacturing planning, where both the per-unit cost and resource requirement to remanufacture a core are uncertain parameters that are assumed to reside in two different uncertainty sets; box and ellipsoidal. We analyse both uncapacitated and capacitated cases, and based on extensive numerical analysis, conclude that while on average, there is still value in grading, it becomes significantly smaller when the inherent uncertainty is accounted for. For the capacitated case, we also consider a cost for grading and find that it may cause a significant deterioration in the value of grading, if not rendering the grading totally useless. We show the validity of our approach through extensive numerical analyses
Migration regime and “language part of work”: Experiences of Syrian refugees as surplus population in the Turkish labor market
No full textThe literature on migration, language and employment is dominated by the human capital approach and promotes multilingualism as a universal good. This paper examines the relationship between language and work for migrants illustrating how they are ascribed value as capital according to their position and the "language part of work." First, we trace a genealogy of the migration regime in relation to the labor and linguistic market of migrants in Turkey, characterized by informality and exploitation. Then, we look at the experiences of refugees qualitatively to show how language is differentially valued and has modest effects on social mobility. We argue that language learning instead of stemming from individuals' possession of capital should be examined within a broader linguistic and employment framework. This research goes beyond conventional wisdom about the centrality of language as a means to improve employment by shedding light on the structure that shapes language value.Mercator-IPC fellowship (2018-2019) at Istanbul Policy Center at Sabanci University ; Koc University ; European Union’s Horizon Europ
Istanbul: The city as an urban palimpsest
No full textThe metropolitan cities of the world continue to grow rapidly with their dynamic, mostly chaotic features that perpetually contain randomness, notwithstanding their specific differences. These inevitably constantly changing and transforming cities are shaped together with their permanent inhabitants and produce new urban spaces. In this regard, Istanbul has always been a laboratory for architectural applications, research and education rightfully due the numerous potentials it embodies. In this context, informal trainings and activities carried out outside the programs in architectural schools are increasingly becoming more important, and Istanbul is used as an instrument for these studies. From this point of view, so as to contribute to the discussions on the palimpsest character of Istanbul and to provoke post-graduate students and young architects to question the multi-layered state of the city, ‘Culture and Space’ Network has been organizing paper selections in Turkey for eight years. This current article reviews and analyzes a selected group of awarded papers from the paper selections in order to explore the concept of ‘urban palimpsest’, to read and understand the multi-layered and palimpsest structure of Istanbul from their perspectives, and to highlight their interpretations
Relationship with extended family following divorce: a closer look at contemporary times
No full textExtended family relationships may serve as either resources or as additional stressors as families negotiate stressful life events such as divorce. As families go through several readjustments and reorganizations following divorce, extended family members both affect and are affected by these changes. Existing literature provides valuable insights regarding post-divorce extended family relationships but they were mostly conducted over 25 years ago. In order to provide up-to-date information on current post-divorce extended family relationships, the current paper examined post-divorce relationships with their extended family members of 369 divorced individuals with children (66% women and 34% men). Participants reported on contact and closeness with their extended family members, as well as perceived influence of extended family members on their daily lives. In addition, the supportive role of extended family following divorce was explored. Results, generally, suggests that divorced individuals tend to have higher levels of contact and emotional closeness with extended family members from their own family rather than former spouse’s family. Relatedly, people reported higher perceived influence and support received from one’s own family. Demographic variables such as gender and years since divorce appeared to influence post-divorce relationships with extended family members in unique ways
Patterns of associations between maternal symptoms and child problem behaviors: the mediating role of mentalization, negative intentionality, and unsupportive emotion socialization
No full textWe examined how maternal depression, anxiety, hostility, mentalization, negative intentionality (NI), and unsupportive emotion socialization (UES) predict child internalizing and externalizing problem behaviors (CIEPB). Mothers (N = 537) of toddlers (M-age = 23.26 months,Range10-44 months) completed the Brief Symptom Inventory, the Parental Reflective Functioning Questionnaire, the Infant Intentionality Questionnaire, the Coping with Children's Negative Emotions Scale, and the Child Behavior Checklist. All maternal symptoms negatively predicted mentalization and positively predicted NI, UES, and CIEPB. NI and UES mediated the relationship between maternal symptoms and CIEPB. Negative intentionality mediated the link between maternal hostility and internalizing behaviors, indicating a possible intervention area. Mentalization had an effect on externalizing behaviors only for high-SES, anxious mothers, underscoring the role of SES. Thus, the relationship between maternal symptoms, cognitive and behavioral parenting characteristics and CIEPB supports the multifinality principle for early childhood psychopathology development and shows the importance of screening for maternal symptoms and CIEPB.TÜBİTA
A computational workflow for rupture‐to‐structural‐response simulation and its application to Istanbul
No full textScenario-based earthquake simulations at regional scales hold the promise in advancing the state-of-the-art in seismic risk assessment studies. In this study, a computational workflow is presented that combines (i) a broadband Green's function-based fault-rupture and ground motion simulation-herein carried out using the "UCSB (University of California at Santa Barbara) method", (ii) a three-dimensional physics-based regional-scale wave propagation simulation that is resolved at fmax=11.2 Hz, and (iii) a local soil-foundation-structure finite element analysis model. These models are interfaced with each other using the domain reduction method. The innermost local model-implemented in ABAQUS-is additionally enveloped with perfectly matched layer boundaries that absorb outbound waves scattered by the structures contained within it. The intermediate wave propagation simulation is carried out using Hercules, which is an explicit time-stepping finite element code that is developed and licensed by the CMU-QUAKE group. The devised workflow is applied to a 80x40x40 km3 region on the European side of Istanbul, which was modeled using detailed soil stratigraphy data and realistic fault rupture properties, which are available from prior microzonation surveys and earthquake scenario studies. The innermost local model comprises a chevron-braced steel frame building supported by a shallow foundation slab, which, in turn, rests atop a three-dimensional soil domain. To demonstrate the utility of the workflow, results obtained using various simplified soil-structure interaction analysis techniques are compared with those from the detailed direct model. While the aforementioned demonstration has a limited scope, the devised workflow can be used in a multitude of ways, for example, to examine the effects of shallow-layer soil nonlinearities and surface topography, to devise site- and structure-specific seismic fragilities, and for calibrating regional loss models, to name a few.TÜBİTAK ; Texas Advanced Computing Center (TACC
Effect of fuel choice on conductivity and morphological properties of samarium doped ceria electrolytes for IT-SOFC
No full textThe present investigation is emphasized on the effect of various combustion agents on the crystal properties, surface microstructure, and oxygen ion conductivity of 20% mole-Sm doped ceria (Ce0.80Sm0.20O1.90/SDC20) ceramics as solid electrolyte for IT-SOFCs. The most widely used combustion agents for engineering ceramic production as ethylene glycol, diethylene glycol, triethylene glycol, L-alanine, L-valine, glycine, citric acid monohydrate, urea, and EDTA-citric acid were compared in terms of SDC20 properties. X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and electrochemical impedance spectroscopy (EIS) were used to determine the microstructure properties, crystal structure and ionic conductivity of SDC20 powder. XRD pattern of the ceramics revealed the formation of single-phase fluorite structure. According to the results of electrochemical analysis, the maximum total ionic conductivity was observed in SDC20 electrolyte synthesized using triethylene glycol as the fuel among all the synthesized electrolytes (5.72 x 10(-2) S.cm(-1)).Publisher versio