Load-aware Channel Selection for 802.11 WLANs with Limited Measurement

It has been known that load unaware channel selection in 802.11 networks results in high level interference, and can significantly reduce the network throughput. In current implementation, the only way to determine the traffic load on a channel is to measure that channel for a certain duration of time. Therefore, in order to find the best channel with the minimum load all channels have to be measured, which is costly and can cause unacceptable communication interruptions between the AP and the stations. In this paper, we propose a learning based approach which aims to find the channel with the minimum load by measuring only limited number of channels. Our method uses Gaussian Process Regressing to accurately track the traffic load on each channel based on the previous measured load. We confirm the performance of our algorithm by using experimental data, and show that the time consumed for the load measurement can be reduced up to 46% compared to the case where all channels are monitored.Comment: accepted to IC

Approaching Optimal Centralized Scheduling with CSMA-based Random Access over Fading Channels

Carrier Sense Multiple Access (CSMA) based distributed algorithms can attain the largest capacity region as the centralized Max-Weight policy does. Despite their capability of achieving throughput-optimality, these algorithms can either incur large delay and have large complexity or only operate over non-fading channels. In this letter, by assuming arbitrary back-off time we first propose a fully distributed randomized algorithm whose performance can be pushed to the performance of the centralized Max-Weight policy not only in terms of throughput but also in terms of delay for completely-connected interference networks with fading channels. Then, inspired by the proposed algorithm we introduce an implementable distributed algorithm for practical networks with a reservation scheme. We show that the proposed practical algorithm can still achieve the performance of the centralized Max-Weight policy.Comment: accepted to IEEE Communications Letter

A new record of zerconid mites (Acari, Mesostigmata, Zerconidae) from the Thrace region of Turkey

In this study, Prozercon martae Ujvári, 2010 is recorded for the first time from Turkey. On the basis of the samples collected from the Thrace region of Turkey, its morphological features are given with drawings. © TÜBITAK

Throughput Optimal Multi-user Scheduling via Hierarchical Modulation

We investigate the network stability problem when two users are scheduled simultaneously. The key idea is to simultaneously transmit to more than one users experiencing different channel conditions by employing hierarchical modulation. For two-user scheduling problem, we develop a throughput-optimal algorithm which can stabilize the network whenever this is possible. In addition, we analytically prove that the proposed algorithm achieves larger achievable rate region compared to the conventional Max-Weight algorithm which employs uniform modulation and transmits a single user. We demonstrate the efficacy of the algorithm on a realistic simulation environment using the parameters of High Data Rate protocol in a Code Division Multiple Access system. Simulation results show that with the proposed algorithm, the network can carry higher user traffic with lower delays.Comment: 4 pages, 2 figures, submitte

Prozercon banazensis sp. Nov. (Acari: Mesostigmata: Zerconidae), a new species of zerconid mite from Turkey, with a new record

In this study, Prozercon banazensis sp. nov. is described and illustrated from female and deutonymph specimens collected in Kütahya and Uşak provinces (Turkey). Morphological features of P. morazae Ujvári, 2011, which is a new record for the Turkish fauna, are also given with drawings. Information on habitat and distribution for each species is also provided. © TÜBİTAK

Energy-Optimal Scheduling in Low Duty Cycle Sensor Networks

Energy consumption of a wireless sensor node mainly depends on the amount of time the node spends in each of the high power active (e.g., transmit, receive) and low power sleep modes. It has been well established that in order to prolong node's lifetime the duty-cycle of the node should be low. However, low power sleep modes usually have low current draw but high energy cost while switching to the active mode with a higher current draw. In this work, we investigate a MaxWeightlike opportunistic sleep-active scheduling algorithm that takes into account time- varying channel and traffic conditions. We show that our algorithm is energy optimal in the sense that the proposed ESS algorithm can achieve an energy consumption which is arbitrarily close to the global minimum solution. Simulation studies are provided to confirm the theoretical results

Patient-centered outcomes of vertebroplasty via questionnaire

Purpose: Our aim was to evaluate patient centred outcomes of patients with compression fractures treated by vertebroplasty. Methods: Patients with compression fractures treated by vertebroplasty procedure between 2013- 2016 was examined with a 3-question through telephone call. Results: Fifty-two patients completed the telephone satisfaction survey. Of these, 92.5 % of answerers said the procedure was acceptable, 86.5% had full or partial pain remission and 78.8 % would have the procedure again. Conclusions: The use of vertebroplasty is supported by randomized trials in osteoporotic and malignant compression fractures. To the results of our study, patients believe vertebroplasty is a tolerable procedure that produces full or partial pain remission and would try the same procedure again if needed.Publisher's Versio

An Integral Equation Approach For The Solution Of The Stokes Flow With Hermite Surface

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Üç boyutlu Stokes akışını çözmek amacıyla sınır integral yöntemiyle beraber dörtgen Hermit yüzeyler kullanılarak bir integral denklem yöntemi geliştirilmiştir. Sayısal sonuçlar, sınır sıralama yönteminden ve daimi Stokes denkleminin temel çözümleri olan Stokesletlerin sürekli dağılımından yararlanılarak elde edilmiştir. Dörtgen yüzey elemanları, komşu elemanlar arasındaki yüzey normal vektörünün sürekliliğini sağlayan hermite fonksiyonları kullanılarak tanımlanmıştır. Tekil integraller tanh-sinh tümlev yöntemi, tekil olmayan integraller ise Gauss-Legendre yöntemi kullanılarak sayısal olarak hesaplanmıştır. Sayısal algoritma ilk olarak küre etrafindaki üç boyutlu Stokes akışında doğrulanmıştır. Sonrasında algoritma küresel parçacıkların sedimantasyonu problemi için uygulanmıştır.An integral equation method has been developed to solve the three-dimensional Stokes flow using a quadrilateral Hermite based function approach to the boundary integral method. The numerical solutions are obtained by utilizing the boundary collocation method as well as the continuous distribution of Stokeslets, which are the fundamental solutions of the steady Stokes equations. The quadrilateral surface elements are based on the bi-cubic hermite functions that allows the continuous variation of the surface normal vectors between neighboring elements. The singular integrations are evaluated numerically using the tanh-sinh quadrature rule meanwhile non-singular integrals are evaluated using the Gauss-Legendre quadrature rule. The numerical algorithm is initially validated for the three-dimensional unbounded Stokes flow around a sphere. Then the algorithm is applied to the sedimentation of spherical particles. Keywords: Integral equation method, Stokes flow, Hermite functions, singular integrals, sedimentation