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Search Results: 1 - 10 of 1132 matches for " Hakan Hjalmarsson "
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Outlier robust system identification: a Bayesian kernel-based approach
Giulio Bottegal,Aleksandr Y. Aravkin,Hakan Hjalmarsson,Gianluigi Pillonetto
Statistics , 2013,
Abstract: In this paper, we propose an outlier-robust regularized kernel-based method for linear system identification. The unknown impulse response is modeled as a zero-mean Gaussian process whose covariance (kernel) is given by the recently proposed stable spline kernel, which encodes information on regularity and exponential stability. To build robustness to outliers, we model the measurement noise as realizations of independent Laplacian random variables. The identification problem is cast in a Bayesian framework, and solved by a new Markov Chain Monte Carlo (MCMC) scheme. In particular, exploiting the representation of the Laplacian random variables as scale mixtures of Gaussians, we design a Gibbs sampler which quickly converges to the target distribution. Numerical simulations show a substantial improvement in the accuracy of the estimates over state-of-the-art kernel-based methods.
The Analysis of the Van-Ercis Earthquake, October 23, 2011 Turkey, for the Transportation Systems in the Region  [PDF]
Hakan Aslan
Open Journal of Earthquake Research (OJER) , 2013, DOI: 10.4236/ojer.2013.24009
Abstract:

This paper investigates the effect of the Van-Ercis, Turkey, (Mw: 7.2)earthquake occurring on 23rd of October, 2011 on the transportation networks in the region. The basic incentivefor this research is to conceptualise the reliability and performance of the networks after the earthquake through the operational and topological analysis of the system. The demand and composition of the traffic along with the behaviour of the pedestrians were taken into account to evaluate the performance of the networks. In addition, the general structure of the cities and towns, as far as planning is concerned, is also paid attention and regarded as one of the main elements for the appraisal. The outcomes obtained are thought very important to be guidance for the expected Istanbul earthquake in the near future.

Wireless Capsule Cystoscopy: How Near? How Far?  [PDF]
Hakan ?ztürk
Open Journal of Urology (OJU) , 2014, DOI: 10.4236/oju.2014.44007
Abstract:

It is a fact that performing endoscopy using conventional methods requires substantial time and development of alternative diagnostic modalities. Replacement of rigid endoscopes with flexible and digital devices in time, faster performance of the procedures and reduced time for them to turn back to work brought about the expectancy. It was possible that easier and more reliable methods could exist. Idea of capsule endoscopy was born following examination of the gastrointestinal tract with an endoscope with shape of a capsule. Although idea of capsule endoscopy was suggested long years ago, it fell behind the advances in conventional step of the endoscopy, especially developmental speed of the flexible devices. Furthermore, three-dimensional (3D) organ views can be processed digitally by means of sophisticated software in the fields of computerized tomography and magnetic resonance imaging. Thus, virtual cystoscopy of high resolution and specificity is possible by means of both methods. Wireless capsule endoscopy is still in the experimental stage. “Steerable independent intracorporeal endoscope” with feature of consecutive instillation in addition to its diagnostic utility is not a dream.

Power System Analysis of an Aero-Engine  [PDF]
Onder Turan, Hakan Aydin
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.34060
Abstract:

The aim of this study is analyzed in detail for better understanding of energy and power of an aero-engine. In this regard, this study presents energy equations were applied to the turbofan engine components. The engine has a thrust range of 82 to 109 kN. It consists of fan, axial low pressure compressor (LPC), axial high pressure compressor (HPC), an annular combustion chamber, high-pressure turbine (HPT) and low pressure turbine (LPT). The results show that power of the engine flow approaches a maximum value to be 82.85 MW in the combustor outlet, while minimum power is observed at LPC inlet with the value of 1.37 MW. Furthermore, important parameters of the engine are also analyzed from reverse-engineering method. It is expected that results of this study will be beneficial of power, cogeneration and aero-propulsive generation systems in similar environment.

An Application of Kalman Filtering and Artificial Neural Network with K-NN Position Detection Technique  [PDF]
Hakan Koyuncu, Baki Koyuncu
Wireless Sensor Network (WSN) , 2017, DOI: 10.4236/wsn.2017.98013
Abstract: RFID technology is one of the important technologies to determine the object locations. Distances are calculated with respect to calibration curves of RSSI amplitudes. The aim of this study is to determine the 2D position of mobile objects in the indoor environment. The importance of the work is to show that localization by using Artificial Neural Network plus Kalman Filtering is more accurate than using classical KNN method. An indoor wireless sensing network is established with strategically stationed RFID transmitter nodes and a mobile object with a RFID receiver node. A fingerprint map is generated and K-Nearest Neighbourhood algorithm (KNN) is deployed to calculate the object locations. Fingerprint coordinates and RSS values received at these coordinates are deployed to set up an Artificial Neural Network (ANN). This network is used to determine the unknown object locations by using RSS values received at these locations. The accuracy of object localization is found to be better with ANN technique than KNN technique. Object coordinates, determined with ANN technique, are subjected to Kalman filtering. The results show that localization accuracies are improved and localization error distances are reduced by 46% with the deployment of ANN + Kalman Filtering.
Bayesian kernel-based system identification with quantized output data
Giulio Bottegal,Gianluigi Pillonetto,H?kan Hjalmarsson
Statistics , 2015,
Abstract: In this paper we introduce a novel method for linear system identification with quantized output data. We model the impulse response as a zero-mean Gaussian process whose covariance (kernel) is given by the recently proposed stable spline kernel, which encodes information on regularity and exponential stability. This serves as a starting point to cast our system identification problem into a Bayesian framework. We employ Markov Chain Monte Carlo (MCMC) methods to provide an estimate of the system. In particular, we show how to design a Gibbs sampler which quickly converges to the target distribution. Numerical simulations show a substantial improvement in the accuracy of the estimates over state-of-the-art kernel-based methods when employed in identification of systems with quantized data.
Deep Venous Thrombosis in Breast Cancer Patients Using Tamoxifen, a Hypothesis  [PDF]
Meral Sayin, Bekir Hakan Bakkal
Journal of Cancer Therapy (JCT) , 2011, DOI: 10.4236/jct.2011.25081
Abstract: Breast cancer is the most frequently diagnosed cancer in women and systematic therapy is an essential component of disease. Hormonal therapy, cytotoxic chemotherapy and the more recently introduced biological therapies are routinely employed in the vast majority of patients. Several pharmaceuticals that affect the estrogenic pathways have been studied as chemopreventive agents. Tamoxifen is an anti-estrogenic drug used in the treatment of estrogen receptor positive breast cancer patients. One of the important side-effects of tamoxifen is thromboembolic events like deep venous thrombosis. Tamoxifen also causes an increase in mean platelet volume. We hypothesize that thromboembolic effect of tamoxifen is via increase of mean platelet volume.
Determination of Customer Satisfaction in Conservative Concept Hotels by Ordinal Logistic Regression Analysis  [PDF]
Hakan Eygu, Ali Caglar Gulluce
Journal of Financial Risk Management (JFRM) , 2017, DOI: 10.4236/jfrm.2017.63020
Abstract: The purpose of this study was to determine the satisfaction level and the expectations of the conservative hotel customers during their stay. For this purpose, a survey was conducted for customers who prefer to stay in conservative hotel facilities. Ordinal logistic regression analysis was conducted using a statistical package program on the data obtained with the help of questionnaires. 430 customers who were staying in conservative hotels were asked to answer 41 questions in the survey. As a result of the research, demographic characteristics of conservative hotel customers were found to be statistically significant between the dependent variable and their status of education levels, occupation status, monthly income, nationality, duration of hotel stay, previous hotel stay, and the desire to stay again in the same hotel. This is a unique study to determine as to whether the characteristics of conservative hotel customers in hotel facilities differ according to the individual and socio-cultural characteristics of customers, since the customer expectancy changes according to the period and conditions of the time of operation and to compare the current situation with the expectations of the customers.
Hypoxia upregulates the expression of the NDRG1 gene leading to its overexpression in various human cancers
Hakan Cangul
BMC Genetics , 2004, DOI: 10.1186/1471-2156-5-27
Abstract: Hypoxia and its mimetics induce in vitro expression of NDRG1 gene and cause the accumulation of Ndrg1 protein. Protein levels remain high even after cells revert to normoxia. Although HIF-1 is involved in the regulation of NDRG1, long term hypoxia induces the gene to some extent in HIF-1 knock-out cells. In the majority of human tissues studied, Ndrg1 protein is overexpressed in cancers compared to normal tissues and also reflects tumour hypoxia better than HIF-1 protein.Hypoxia is an inducer of the NDRG1 gene, and nickel probably causes the induction of the gene by interacting with the oxygen sensory pathway. Hypoxic induction of NDRG1 is mostly dependent on the HIF-1 transcription factor, but HIF-1 independent pathways are also involved in the regulation of the gene during chronic hypoxia. The determination of Ndrg1 protein levels in cancers may aid the diagnosis of the disease.Cancer is a leading cause of death in humans, and current studies in the clinical area focus on either the early detection of this disease or on the development of new selective treatment tools. New tumour markers can provide aid in cancer diagnosis and create novel treatment opportunities.Ndrg1, also named Cap43, Drg 1, RTP and rit42 following the discovery of its gene (NDRG1) in different laboratories, is a stress responsive protein which shuttles between cytoplasm and nucleus upon certain insults [1-5]. After its independent discovery in our lab [1], we worked on the expression of this gene and the availability of its protein product in human cells and tissues under different conditions.Since our origin for the induction of the NDRG1 gene was nickel exposure, we worked on possible ways by which nickel could change the expression of this gene. Among the mechanisms investigated were epigenetic changes (DNA methylation and histone acetylation), signal transduction pathways (tyrosine phosphorylation, adenylate cyclase cascade, calmodulin, PKC, PI3-K), and ROS-mediated activation. However, no
Continuing medical education in Turkey: Recent developments
Hakan Yaman
BMC Medical Education , 2002, DOI: 10.1186/1472-6920-2-6
Abstract: Since the year 1994, 2348 applications to the Continuing Medical Education board have been made (mostly for scientific meetings), and 95% of these applications have been accepted. Physicians received 139.014 credits during this time. This number is increasing every year. Meeting organisers' demand for such a kind of evaluation is increasing, because participants increasingly request it.Efforts for revalidation and re-certification of physicians have not been completely successful yet. In the near future the Co-ordination Council of Medical Speciality Societies is going to oblige member associations to establish speciality boards. This will be the first step to the conventional use of Continuing Medical Education credits in occupational evaluation. Time-limited re-certification of physicians is the principal goal of Turkish Medical Association. Efforts to implement this change in legislation are being made.The Turkish Medical Association (TMA) has worked for many years on the idea of developing strategies that would contribute to raising professional standards for all Turkish medical doctors. Continuing medical education (CME) is essential in a country with an unequal geographic distribution of wealth and health resources, in which most of the doctors work in cities located in Western Turkey. Although medical education programs in Turkey are innovative and internationally acknowledged [1], it is very clear that basic and clinical medical sciences will expand exponentially and the technology and practice of medicine will change greatly with time. Therefore the body of knowlede in all medical scientific fields will accumulate, so that it will be impossible for any medical doctor to be aware of all of the new technology and knowledge in his field [2].Another outstanding problem is that the doctor himself cannot appreciate his/her needs sufficiently to maintain a base of current medical knowledge. Therefore all doctors should be encouraged to improve their medical knowle
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