Browsing by Subject "Convergence"

Now showing 1 - 17 of 17

Open Access
Approximate MLFMA as an efficient preconditioner
(IEEE, 2007) Malas, Tahir; Ergül, Özgür; Gürel, Levent
In this work, we propose a preconditioner that approximates the dense system operator. For this purpose, we develop an approximate multilevel fast multipole algorithm (AMLFMA), which performs a much faster matrix-vector multiplication with some relative error compared to the original MLFMA. We use AMLFMA to solve a closely related system, which makes up the preconditioner. Then, this solution is embedded in the main solution that uses MLFMA. By taking into account the far-field elements wisely, this preconditioner proves to be much more effective compared to the near-field preconditioners.
Open Access
Architectural requirements for energy efficient execution of graph analytics applications
(IEEE, 2015-11) Özdal, Muhammet Mustafa; Yeşil, Şerif; Kim, T.; Ayupov, A.; Burns, S.; Öztürk, Özcan
Intelligent data analysis has become more important in the last decade especially because of the significant increase in the size and availability of data. In this paper, we focus on the common execution models and characteristics of iterative graph analytics applications. We show that the features that improve work efficiency can lead to significant overheads on existing systems. We identify the opportunities for custom hardware implementation, and outline the desired architectural features for energy efficient computation of graph analytics applications. © 2015 IEEE.
Open Access
Convergence to international financial reporting standards: the case of Turkey
(Inderscience Publishers, 2005) Simga‐Mugan, C.; Hosal-Akman, N.
In this paper, we discuss the progress in the accounting standards in Turkey and provide some insight into the current accounting system as well as the recent regulatory developments following the convergence attempts to the global set of financial accounting standards that is currently referred to as the International Financial Reporting Standards/International Accounting Standards (IFRS/IAS) in Turkey. The paper emphasises variations from and similarities with the IFRS/IAS and lays out a brief history of global convergence activities. The paper concludes with a discussion of the effects of convergence on the financial reporting and accounting systems of domestic and multinational companies, and audit firms in Turkey.
Open Access
Cooperative localization in hybrid infrared/visible light networks: Theoretical limits and distributed algorithms
(Institute of Electrical and Electronics Engineers, 2019) Keskin, M. Furkan; Erdem, Osman; Gezici, Sinan
Light emitting diode (LED) based visible light positioning (VLP) networks can provide accurate location information in environments where the global positioning system (GPS) suffers from severe signal degradation and/or cannot achieve high precision, such as indoor scenarios. In this manuscript, we propose to employ cooperative localization for hybrid infrared/visible light networks that involve multiple LED transmitters having known locations (e.g., on the ceiling) and visible light communication (VLC) units equipped with both LEDs and photodetectors (PDs) for the purpose of cooperation. In the considered scenario, downlink transmissions from LEDs on the ceiling to VLC units occur via visible light signals, while the infrared spectrum is utilized for device-to-device communications among VLC units. First, we derive the Cramer-Rao lower bound (CRLB) and the maximum likelihood estimator (MLE) for the localization of VLC units in the proposed cooperative scenario. To tackle the nonconvex structure of the MLE, we adopt a set-theoretic approach by formulating the problem of cooperative localization as a quasiconvex feasibility problem, where the aim is to find a point inside the intersection of convex constraint sets constructed as the sublevel sets of quasiconvex functions resulting from the Lambertian formula. Next, we devise two feasibility-seeking algorithms based on iterative gradient projections to solve the feasibility problem. Both algorithms are amenable to distributed implementation, thereby avoiding high-complexity centralized approaches. Capitalizing on the concept of quasi-Fej\'er convergent sequences, we carry out a formal convergence analysis to prove that the proposed algorithms converge to a solution of the feasibility problem in the consistent case. Numerical examples illustrate the improvements in localization performance achieved via cooperation among VLC units and evidence the convergence of the proposed algorithms to true VLC unit locations in both the consistent and inconsistent cases. IEEE
Open Access
The effect of IFRS adoption on financial disclosure: does culture still play a role?
(Centre for Promoting Ideas, 2011) Akman, N. H.
This study investigates whether the differences in financial disclosure due to culture have diminished after the use of IFRS. Using 498 firm-year observations for the period of 2004 to 2006 from six countries, the results indicate that the effect of culture still prevail on the amount of disclosure even after the use of IFRS. However, it is also noted that, the level of financial disclosure increases in all countries examined following the adoption of IFRS. Nevertheless, findings of the study show that the use of single set of accounting standards does not completely eliminate the impact of culture on financial disclosure.
Open Access
Energy efficient architecture for graph analytics accelerators
(IEEE, 2016-06) Özdal, Muhammet Mustafa; Yeşil, Şerif; Kim, T.; Ayupov, A.; Greth, J.; Burns, S.; Öztürk, Özcan
Specialized hardware accelerators can significantly improve the performance and power efficiency of compute systems. In this paper, we focus on hardware accelerators for graph analytics applications and propose a configurable architecture template that is specifically optimized for iterative vertex-centric graph applications with irregular access patterns and asymmetric convergence. The proposed architecture addresses the limitations of the existing multi-core CPU and GPU architectures for these types of applications. The SystemC-based template we provide can be customized easily for different vertex-centric applications by inserting application-level data structures and functions. After that, a cycle-accurate simulator and RTL can be generated to model the target hardware accelerators. In our experiments, we study several graph-parallel applications, and show that the hardware accelerators generated by our template can outperform a 24 core high end server CPU system by up to 3x in terms of performance. We also estimate the area requirement and power consumption of these hardware accelerators through physical-aware logic synthesis, and show up to 65x better power consumption with significantly smaller area. © 2016 IEEE.
Open Access
European integration, productivity growth and real convergence: evidence from the new member states
(Elsevier BV, 2009) Kutan, A. M.; Yigit, T. M.
We estimate the determinants of labor productivity growth in 8 new European Union (EU) member states that joined the Union in 2004. Our focus is on the impact of globalization and EU integration efforts on labor productivity growth. Previous studies test the impact of trade using either exports or trade openness. We also test the impact of imports separately on labor productivity growth. Using panel data for 1995-2006 period, we find that globalization has mixed effects. FDI and exports improve productivity, but imports hurt it. Regarding domestic variables, we find that human capital is the most important source of labor productivity growth in the new member states. There is also considerable adjustment of labor productivity towards EU15 levels, indicating significant "catching up" and hence real convergence. Policy implications of the findings are also discussed. © 2009 Elsevier B.V. All rights reserved.
Open Access
Evaluating the maastricht convergence criteria for new prospective european union members
(Türkiye Cumhuriyet Merkez Bankası, 2007) Vesile, Kutlu; Kavrukkoca, N.
This paper aims to assess the macroeconomic condition of the four new prospective members, which are Turkey, Croatia, Bulgaria, and Romania, depending on four Maastricht Convergence Criteria in order to determine which candidate is ready to join EMU. We use cointegration approach to analyze cointegrating relations among inflation rates, interest rate, deficit-to-GDP, and debt-to-GDP. ratios of four candidates in relation to Germany. Bounds Testing and Engle-Granger Cointegration Approach are applied to all criteria to test convergence. None of the convergence criteria for Turkey and Romania in relation to Germany has been achieved. On the other hand, there is evidence of nominal convergence between Croatia and Germany in terms of deficit-to-GDP ratio and interest rates. Also, there is cointegration between deficit-to-GDP ratio of Bulgaria and that of Germany
Open Access
Federated learning and distributed inference over wireless channels
(2023-11) Tegin, Büşra
In an era marked by massive connectivity and a growing number of connected devices, we have gained unprecedented access to a wealth of information, enhancing the reliability and precision of intelligent systems and enabling the de-velopment of learning algorithms that are more capable than ever. However, this proliferation of data also introduces new challenges for centralized learning algorithms for the training and inference processes of these intelligent systems due to increased traffic loads and the necessity of substantial computational resources. Consequently, the introduction of federated learning (FL) and distributed inference systems has become essential. Both FL and distributed inference necessitate communication within the network, specifically, the transmission of model updates and intermediate features. This has led to a significant emphasis on their utilization over wireless channels, underscoring the pivotal role of wireless communications in this context. In pursuit of a practical implementation of federated learning over wireless fading channels, we direct our focus towards cost-effective solutions, accounting for hardware-induced distortions. We consider a blind transmitter scenario, wherein distributed workers operate without access to channel state information (CSI). Meanwhile, the parameter server (PS) employs multiple antennas to align received signals. To mitigate the increased power consumption and hardware cost, we leverage complex-valued, low-resolution digital-to-analog converters (DACs) at the transmitter and analog-to-digital converters (ADCs) at the PS. Through a combination of theoretical analysis and numerical demonstrations, we establish that federated learning systems can effectively operate over fading channels, even in the presence of low-resolution ADCs and DACs. As another aspect of practical implementation, we investigate federated learning with over-the-air aggregation over time-varying wireless channels. In this scenario, workers transmit their local gradients over channels that undergo time variations, stemming from factors such as worker or PS mobility and other transmission medium fluctuations. These channel variations introduce inter-carrier interference (ICI), which can notably degrade the system performance, particularly in cases of rapidly varying channels. We examine the effects of the channel time variations on FL with over-the-air aggregation, and show that the resulting undesired interference terms have only limited destructive effects, which do not prevent the convergence of the distributed learning algorithm. Focusing on the distributed inference concept, we also consider a multi-sensor wireless inference system. In this configuration, several sensors with constrained computational capacities observe common phenomena and engage in collaborative inference efforts alongside a central device. Given the inherent limitations on the computational capabilities of the sensors, the features extracted from the front part of the network are transmitted to an edge device, which necessitates sensor fusion for the intermediate features. We propose Lp-norm inspired and LogSumExp approximations for the maximum operation as a sensor fusion method, resulting in the acquisition of transformation-invariant features that also enable bandwidth-efficient feature transmission. As a further enhancement of the proposed method, we introduce a learnable sensor fusion technique inspired by the Lp-norm. This technique incorporates a trainable parameter, providing the flexibility to customize the sensor fusion according to the unique network and sensor distribution characteristics. We show that by encompassing a spectrum of behaviors, this approach enhances the adaptability of the system and contributes to its overall performance improvement.
Open Access
Fiscal convergence in the European Union
(Elsevier BV, 2008) Kocenda, E.; Kutan, A. M.; Yigit, T. M.
We empirically examine the fiscal convergence of the recent ten European Union (EU) members using the Maastricht fiscal convergence criteria. We test for absolute beta and sigma convergence of the new members in comparison to the Maastricht benchmarks, as well as the EU15 figures, using methodologies that allow for structural breaks. The results show poor fiscal performance in the European Union in general, suggesting that monetary unions do not necessarily encourage fiscal convergence for its members. © 2008 Elsevier Inc. All rights reserved.
Open Access
Growing tendency to harmonisation with IFRS: some evidences from Turkey
(Inderscience Publishers, 2009) Kocakülâh, M. C.; Şimga-Muğan, C.; Hoşal-Akman, Nazli; Aldogan, M.
Motivated by the recent developments in accounting regulations, we explore the tendency of countries to converge to IFRS for both public and private companies and present some evidence on the issue from an emerging market. We explore how the legal system – civil vs. common law – and the stock market development stage in a country affects the acceptance of IFRS by the regulators. We find that stock market influences the acceptance of IFRS for both public and private companies while the legal system affects the requirement of IFRS for the private companies. In Turkey, different regulatory bodies control different types of companies. Capital Markets Board that controls the listed companies issued the first set of translated IFRS in 2003. Established in 2002, Turkish Accounting Standards Board (TASB) is responsible to translate and issue the international accounting standards. Examination of issue and effective dates of both standards reveals that TASB closely follows the IASB efforts.
Open Access
Income inequality and economic convergence in Turkey: a spatial effect analysis
(Sage Publications, 2009) Yildirim, J.; Öcal, N.; Özyildirim, S.
Even though the convergence of regional per capita income has been a highly debated issue internationally, empirical evidence regarding Turkey is limited as well as contradictory. This article is an attempt to investigate regional income inequality and the convergence dynamics in Turkey for the time period 1987-2001. First, the Theil coefficient of concentration index is used to analyze the dispersion aspects of the convergence process. The geographically based decomposition of inequality suggests a strong correlation between the share of interregional inequality and spatial clustering. Then, we estimate convergence dynamics employing alternative spatial econometric methods. In addition to the global models, we also estimate local models taking spatial variations into account. Empirical analysis indicates that geographically weighted regression improves model fitting with better explanatory power. There is considerable variation in speed of convergence of provinces, which cannot be captured by the traditional beta convergence analysis.
Open Access
Jamming bandits-a novel learning method for optimal jamming
(Institute of Electrical and Electronics Engineers Inc., 2016) Amuru, S.; Tekin, C.; Van Der Schaar, M.; Buehrer, R.M.
Can an intelligent jammer learn and adapt to unknown environments in an electronic warfare-type scenario? In this paper, we answer this question in the positive, by developing a cognitive jammer that adaptively and optimally disrupts the communication between a victim transmitter-receiver pair. We formalize the problem using a multiarmed bandit framework where the jammer can choose various physical layer parameters such as the signaling scheme, power level and the on-off/pulsing duration in an attempt to obtain power efficient jamming strategies. We first present online learning algorithms to maximize the jamming efficacy against static transmitter-receiver pairs and prove that these algorithms converge to the optimal (in terms of the error rate inflicted at the victim and the energy used) jamming strategy. Even more importantly, we prove that the rate of convergence to the optimal jamming strategy is sublinear, i.e., the learning is fast in comparison to existing reinforcement learning algorithms, which is particularly important in dynamically changing wireless environments. Also, we characterize the performance of the proposed bandit-based learning algorithm against multiple static and adaptive transmitter-receiver pairs.
Open Access
Media convergence in animation : an analysis of aesthetic uniformity
(2017-01) Gündeş, Feridun
This thesis analyzes the uniformity in animation aesthetics within the framework of convergence theory. The sources of aesthetic diversity in animation art are demonstrated along with the process though which these became precarious over time as realism became an end in itself. It is suggested that the diversity is due to the independent use of such elements of the screen image as the line and the form, and such elements related to movement as the motion and the time. When these elements are harnessed to create a realistic image and movement, the diversity is lost, and there occurs uniformity. This has been aggravated with the emerging computer technology which made it possible to create highly indexical photorealistic images and videorealistic movement. This process can be interpreted as a special case of digital and technological media convergence, which brought together previously separate design activities, and merged their aesthetic principles. The result is an hybrid aesthetics prevalent over separate domains, including animation. Due to industry related reasons, this realism based aesthetic approach became so dominant that it pushed all the others to obscurity, causing a decrease in diversity and increase in uniformity in animation aesthetics.
Open Access
A new method for the steady-state analysis of periodically excited nonlinear circuits
(Institute of Electrical and Electronics Engineers, 1996-12) Celik, M.; Atalar, Abdullah; Tan, M. A.
We propose a new method for the steady state analysis of periodically excited nonlinear microwave circuits. It is a modified and more efficient form of Newton-Raphson iteration based harmonic balance (HB) technique. It solves the convergence problems of the HB technique at high drive levels. The proposed method makes use of the parametric dependence of the circuit responses on the excitation level. It first computes the derivatives of the complex amplitudes of the harmonics with respect to the excitation level efficiently and then finds the Pade approximants for the amplitudes of the harmonics using these derivatives.
Open Access
Wendt versus Pollock: Toward visual semiotics in the discipline of IR theory
(De Gruyter Mouton, 2020-11-19) Güner, Serdar
We focus on a key IR Theory article by Alexander Wendt (1992) and two Jackson Pollock paintings. Our aim is to identify meanings Pollock’s art communicates and reveals for Wendt (1992). It derives from an appeal to visual imagination and a desire for semiotic interpretation of Constructivist view of anarchy. The visual sign is an association such that there is Wendt’s theoretical claim on the one hand and an abstract painting on the other. We do not gaze at Wendt’s claim, we read it. We do not read a painting, look at it. This remark does not imply a one-way relationship. We can argue that a specific painting comes to life in our mind where colored movements are inextricably mixed up when we read the constructivist claim. Both Pollock paintings selected for our sign-making effort confirm the dynamic character of Constructivism and reveal not only three but countlessly many anarchies in international relations. They foment our assessments of abrupt changes of intersubjectivity among states. Cyclicality of dripped paints provides an anchor to fix Wendt’s anarchy conceptualization in these structural-abstract paintings. As to Wendt’s concept of anarchy, it acts as a helper, as a standard, against which interpretations of Pollock’s artwork construct meanings.
Open Access
Winds of change in accounting practices in an emerging market: Some observations and thoughts
(Inderscience Publishers, 2009) Hosal-Akman, Nazlı; Simga-Mugan, C.; Arikboga, D.
In Turkey, publicly traded companies are required to comply with a new set of standards that are essentially similar to the International Financial Reporting Standards (IFRS) since 2005. In this study, we use the results of a survey carried out in Turkey with accounting or finance executives of publicly traded companies regarding their perceptions of the new set of standards and their expectations from the policy makers, compare the findings of global research with the survey results, and report our observations and opinion. The survey results suggest that there was lack of knowledge and experience for appropriate implementation - a common point raised globally as well. Early observations and findings reflect that, although a lot has been achieved on the way to convergence, more consensus and guidance from the national and international standard setters are necessary to fully realise the expected benefits of IFRS.