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Articles 23491 - 23520 of 27383

Full-Text Articles in Engineering

The Analysis Of A Semiconductor Single Asymmetric And Symmetric Step-Index Laser For Even And Odd Fields By Alpha Method, Mustafa Temi̇z, Mehmet Ünal Jan 2010

The Analysis Of A Semiconductor Single Asymmetric And Symmetric Step-Index Laser For Even And Odd Fields By Alpha Method, Mustafa Temi̇z, Mehmet Ünal

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, semiconductor step-index single waveguide has been analyzed by Alpha Method. A requested quantity of wave guide can be obtained in terms of normalized propagation constant, which is represented by alpha belonging to active region. Based on this method, structural properties of the material containing any requested quantity of the waveguide is theoretically calculated, when the width of the active region, the refractive indices of the regions and the wavelength are given. In the TE mode some important parameters, such as the propagation constants for regions of the semiconductor step-index single waveguide, the wave numbers, the effective index …

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Fractional Order Sliding Mode Control With Reaching Law Approach, Mehmet Önder Efe Jan 2010

Fractional Order Sliding Mode Control With Reaching Law Approach, Mehmet Önder Efe

Turkish Journal of Electrical Engineering and Computer Sciences

Fractional order sliding mode control is studied in this paper. The control objectives are achieved by adopting the reaching law approach of sliding mode control. The main contribution of this work is to show that the philosophy of integer order sliding mode control is valid also for the systems represented by fractional order operators. A sufficient condition and its implications for stability are given. Matched and unmatched uncertainties are studied. The attractor nature of the switching manifold is analyzed together with a stable sliding subspace design condition. The claims are justified through a set of simulations and the results obtained …

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A Novel Algorithm For Sensorless Motion Control Of Flexible Structures, Islam Shoukry Mohammed Khalil, Emrah Deni̇z Kunt, Asif Sabanovic Jan 2010

A Novel Algorithm For Sensorless Motion Control Of Flexible Structures, Islam Shoukry Mohammed Khalil, Emrah Deni̇z Kunt, Asif Sabanovic

Turkish Journal of Electrical Engineering and Computer Sciences

This article demonstrates the validity of using an actuator as a single platform for measurements during a motion control assignment of flexible systems kept free from any kind of measurement. System acceleration level dynamics, parameters and interaction forces with the environment are coupled in an incident reaction torque that naturally rises when a flexible system is subjected to an action imposed by an attached actuator to the system. This work attempts to decouple each of the system parameters out of the incident coupled reaction torque at the interface point of the actuator with the flexible system by way of measurements …

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Modeling And Control Of Flow Problems By Adaptation-Based Linear Parameter Varying Models, Coşku Kasnakoğlu Jan 2010

Modeling And Control Of Flow Problems By Adaptation-Based Linear Parameter Varying Models, Coşku Kasnakoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a systematic modeling and control approach for flow problems is considered. A nonlinear Galerkin model is obtained from the partial differential equations (PDEs) describing the flow; and a Linear Parameter Varying (LPV) model is constructed to approximate the Galerkin model, where the parameter variation of the LPV model is controller by an adaptation mechanism. The LPV model is then treated as a surrogate on which the control design is carried out, where the parameter variations provide a range of uncertainty in which the control design must perform satisfactorily. It is shown that if certain conditions are met, …

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Experimental Investigation Of Shaft Transducerless Speed And Position Control Of Ac Induction And Interior Permanent Magnet Motors, Ömer Göksu, Ahmet Masum Hava Jan 2010

Experimental Investigation Of Shaft Transducerless Speed And Position Control Of Ac Induction And Interior Permanent Magnet Motors, Ömer Göksu, Ahmet Masum Hava

Turkish Journal of Electrical Engineering and Computer Sciences

In order to drive AC motors with high efficiency and high motion performance, and to provide accurate speed/position control, motor shaft speed and/or position feedback is required. For this purpose, usually transducers (encoder, tachogenerator, resolver, etc.) are installed on the shaft. However, transducers are not preferred in most of the applications since they increase the cost and decrease the reliability of the drive due to their failure prone structure and connections. In such applications, the speed and/or position information of the motor is obtained by estimation methods without using shaft transducers. In this work, motor types and speed/position estimation methods …

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Direct Discrete-Time Control Of Port Controlled Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer Jan 2010

Direct Discrete-Time Control Of Port Controlled Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer

Turkish Journal of Electrical Engineering and Computer Sciences

The direct discrete time control of Port Controlled Hamiltonian Systems (PCHS) in the sense of energy shaping and damping injection is considered. In order to give a direct discrete time design method for PCHS, firstly an appropriate discrete gradient is proposed, which enables the derivation of a discrete time equation corresponding to the discrete time counterpart of Hamiltonian Systems. Using this proposed discrete-time model, the discrete-time counterpart of Passivity Based Control (PBC) technique is developed for n-degrees-of-freedom mechanical systems. The discrete-time control rules which correspond to the energy shaping and damping assignment are obtained directly using the discrete time model …

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The Use Of Fpga In Field-Oriented Control Of An Induction Machine, Özkan Akin, İrfan Alan Jan 2010

The Use Of Fpga In Field-Oriented Control Of An Induction Machine, Özkan Akin, İrfan Alan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, the feasibility of embedding the field oriented control (FOC) of an induction machine into field programmable gate arrays (FPGA) is investigated. An indirect FOC of an induction machine is simulated in a Matlab Simulink environment using a Xilinx System Generator implemented in a Xilinx Spartan-3 XC3S200 FPGA board. Design of the developed controller for the induction machine is simulated via a Simulink full digital platform. The resulting design has a flexible and modular structure where the designer can customize the hardware blocks by changing the number of inputs, outputs, and algorithm when it is compared to the …

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Fuzzy Adaptive Neural Network Approach To Path Loss Prediction In Urban Areas At Gsm-900 Band, Türkan Erbay Dalkiliç, Berna Yeşi̇m Hanci, Ayşen Apaydin Jan 2010

Fuzzy Adaptive Neural Network Approach To Path Loss Prediction In Urban Areas At Gsm-900 Band, Türkan Erbay Dalkiliç, Berna Yeşi̇m Hanci, Ayşen Apaydin

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the results of the Adaptive-Network Based Fuzzy Inference System (ANFIS) for the prediction of path loss in a specific urban environment. A new algorithm based ANFIS for tuning the path loss model is introduced in this work. The performance of the path loss model which is obtained from proposed algorithm is compared to the Bertoni-Walfisch model, which is one of the best studied for propagation analysis involving buildings. This comparison is based on the mean square error between predicted and measured values. According to the indicated error criterion, the errors related to the predictions that are obtained …

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Behaviors Of Real-Time Schedulers Under Resource Modification And A Steady Scheme With Bounded Utilization, Refi̇k Samet, Orhan Fi̇kret Duman Jan 2010

Behaviors Of Real-Time Schedulers Under Resource Modification And A Steady Scheme With Bounded Utilization, Refi̇k Samet, Orhan Fi̇kret Duman

Turkish Journal of Electrical Engineering and Computer Sciences

In this article we present an analysis for task models having random resource needs and different arrival patterns. In hard real-time environments like avionic systems or nuclear reactors, the inputs to the system are obtained from real world by using sensors. And it is highly possible for a task to have different resource needs for each period according to these changing conditions of real world. We made an analysis of schedulers for task models having random resources in each period. Since feasibility tests for usual task models are just limited to some specific schedulers and arrival patterns, we made our …

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Leadership, Libraries, Leed For The Future, Kathryn S. Ames, Greg Heid Jan 2010

Leadership, Libraries, Leed For The Future, Kathryn S. Ames, Greg Heid

Georgia Library Quarterly

The article discusses the use of Leadership in Energy and Environmental Design (LEED) principles in the design of the modern public library. It is stated that an LEED-certified library will have lower costs in energy, systems replacement and maintenance through the use of light-emitting diode (LED) lighting and efficient heating and air conditioning, but that due to special materials, the up-front expense is higher. The inspection of the facility throughout its construction is also noted.

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Computer Forensic Functions Testing: Media Preparation, Write Protection And Verification, Yinghua Guo, Jill Slay Jan 2010

Computer Forensic Functions Testing: Media Preparation, Write Protection And Verification, Yinghua Guo, Jill Slay

Journal of Digital Forensics, Security and Law

The growth in the computer forensic field has created a demand for new software (or increased functionality to existing software) and a means to verify that this software is truly forensic i.e. capable of meeting the requirements of the trier of fact. In this work, we review our previous work---a function oriented testing framework for validation and verification of computer forensic tools. This framework consists of three parts: function mapping, requirements specification and reference set development. Through function mapping, we give a scientific and systemized description of the fundamentals of computer forensic discipline, i.e. what functions are needed in the …

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Table Of Contents Jan 2010

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.

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Table Of Contents Jan 2010

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.

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Clustering Spam Domains And Destination Websites: Digital Forensics With Data Mining, Chun Wei, Alan Sprague, Gary Warner, Anthony Skjellum Jan 2010

Clustering Spam Domains And Destination Websites: Digital Forensics With Data Mining, Chun Wei, Alan Sprague, Gary Warner, Anthony Skjellum

Journal of Digital Forensics, Security and Law

Spam related cyber crimes have become a serious threat to society. Current spam research mainly aims to detect spam more effectively. We believe the identification and disruption of the supporting infrastructure used by spammers is a more effective way of stopping spam than filtering. The termination of spam hosts will greatly reduce the profit a spammer can generate and thwart his ability to send more spam. This research proposes an algorithm for clustering spam domains extracted from spam emails based on the hosting IP addresses and tracing the IP addresses over a period of time. The results show that many …

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Developing Voip Honeypots: A Preliminary Investigation Into Malfeasant Activity, Craig Valli Jan 2010

Developing Voip Honeypots: A Preliminary Investigation Into Malfeasant Activity, Craig Valli

Journal of Digital Forensics, Security and Law

30 years ago PABX systems were compromised by hackers wanting to make long distance calls at some other entities expense. This activity faded as telephony became cheaper and PABX systems had countermeasures installed to overcome attacks. Now the world has moved onto the provision of telephony via broadband enabled Voice over Internet Protocol (VoIP) with this service now being provided as a replacement for conventional fixed wire telephony by major telecommunication providers worldwide. Due to increasing bandwidth it is possible for systems to support multiple voice connections simultaneously. The networked nature of the Internet allows for attackers of these VoIP …

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Adaptation Of Pyflag To Efficient Analysis Of Seized Computer Data Storage, Aleksander Byrski, Wojciech Stryjewski, Bartłomiej Czechowicz Jan 2010

Adaptation Of Pyflag To Efficient Analysis Of Seized Computer Data Storage, Aleksander Byrski, Wojciech Stryjewski, Bartłomiej Czechowicz

Journal of Digital Forensics, Security and Law

Based on existing software aimed at investigation support in the analysis of computer data storage seized during investigation (PyFlag), an extension is proposed involving the introduction of dedicated components for data identification and filtering. Hash codes for popular software contained in NIST/NSRL database are considered in order to avoid unwanted files while searching and to classify them into several categories. The extension allows for further analysis, e.g. using artificial intelligence methods. The considerations are illustrated by the overview of the system's design.

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Avoiding Sanctions At The E-Discovery Meet-And-Confer In Common Law Countries, Milton Luoma, Vicki Luoma Jan 2010

Avoiding Sanctions At The E-Discovery Meet-And-Confer In Common Law Countries, Milton Luoma, Vicki Luoma

Journal of Digital Forensics, Security and Law

The rules of civil procedure in common law countries have been amended to better deal with the requirements of electronic discovery. One of the key changes in case management is the scheduling of a meet-and-confer session where the parties to litigation must meet early in the case before any discovery procedures have begun to exchange information regarding the nature, location, formats, and pertinent facts regarding custody and control of a party’s electronically stored information (ESI). Failure to abide by the rules and participate in good faith at the meet-and-confer session can have dire consequences for the parties and lawyers involved. …

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Malware Forensics: Discovery Of The Intent Of Deception, Murray Brand, Craig Valli, Andrew Woodward Jan 2010

Malware Forensics: Discovery Of The Intent Of Deception, Murray Brand, Craig Valli, Andrew Woodward

Journal of Digital Forensics, Security and Law

Malicious software (malware) has a wide variety of analysis avoidance techniques that it can employ to hinder forensic analysis. Although legitimate software can incorporate the same analysis avoidance techniques to provide a measure of protection against reverse engineering and to protect intellectual property, malware invariably makes much greater use of such techniques to make detailed analysis labour intensive and very time consuming. Analysis avoidance techniques are so heavily used by malware that the detection of the use of analysis avoidance techniques could be a very good indicator of the presence of malicious intent. However, there is a tendency for analysis …

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Digital Records Forensics: A New Science And Academic Program For Forensic Readiness, Luciana Duranti, Barbara Endicott-Popovsky Jan 2010

Digital Records Forensics: A New Science And Academic Program For Forensic Readiness, Luciana Duranti, Barbara Endicott-Popovsky

Journal of Digital Forensics, Security and Law

This paper introduces the Digital Records Forensics project, a research endeavour located at the University of British Columbia in Canada and aimed at the development of a new science resulting from the integration of digital forensics with diplomatics, archival science, information science and the law of evidence, and of an interdisciplinary graduate degree program, called Digital Records Forensics Studies, directed to professionals working for law enforcement agencies, legal firms, courts, and all kind of institutions and business that require their services. The program anticipates the need for organizations to become “forensically ready,” defined by John Tan as “maximizing the ability …

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Solid State Drives: The Beginning Of The End For Current Practice In Digital Forensic Recovery?, Graeme B. Bell, Richard Boddington Jan 2010

Solid State Drives: The Beginning Of The End For Current Practice In Digital Forensic Recovery?, Graeme B. Bell, Richard Boddington

Journal of Digital Forensics, Security and Law

Digital evidence is increasingly relied upon in computer forensic examinations and legal proceedings in the modern courtroom. The primary storage technology used for digital information has remained constant over the last two decades, in the form of the magnetic disc. Consequently, investigative, forensic, and judicial procedures are well-established for magnetic disc storage devices (Carrier, 2005). However, a paradigm shift has taken place in technology storage and complex, transistor-based devices for primary storage are now increasingly common. Most people are aware of the transition from portable magnetic floppy discs to portable USB transistor flash devices, yet the transition from magnetic hard …

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Book Review: Digital Forensic Evidence Examination (2nd Ed.), Gary C. Kessler Jan 2010

Book Review: Digital Forensic Evidence Examination (2nd Ed.), Gary C. Kessler

Journal of Digital Forensics, Security and Law

On the day that I sat down to start to write this review, the following e-mail came across on one of my lists: Person A and Person B write back and forth and create an email thread. Person A then forwards the email to Person C, but changes some wording in the email exchange between A & B. What is the easiest way (and is it even possible) to find out when that earlier email message was altered before sent to Person C? Before you try to answer these questions, read Fred Cohen's Digital Forensic Evidence Examination. His book won't …

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Identifying A Computer Forensics Expert: A Study To Measure The Characteristics Of Forensic Computer Examiners, Gregory H. Carlton, Reginald Worthley Jan 2010

Identifying A Computer Forensics Expert: A Study To Measure The Characteristics Of Forensic Computer Examiners, Gregory H. Carlton, Reginald Worthley

Journal of Digital Forensics, Security and Law

The usage of digital evidence from electronic devices has been rapidly expanding within litigation, and along with this increased usage, the reliance upon forensic computer examiners to acquire, analyze, and report upon this evidence is also rapidly growing. This growing demand for forensic computer examiners raises questions concerning the selection of individuals qualified to perform this work. While courts have mechanisms for qualifying witnesses that provide testimony based on scientific data, such as digital data, the qualifying criteria covers a wide variety of characteristics including, education, experience, training, professional certifications, or other special skills. In this study, we compare task …

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Table Of Contents Jan 2010

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.

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Calibration Of Hdm-4 For Use In Pavement Management Systems (Pms), Nurdin Mushule Dec 2009

Calibration Of Hdm-4 For Use In Pavement Management Systems (Pms), Nurdin Mushule

Tanzania Journal of Engineering and Technology (TJET)

One of major problems of road management in developing countries is the lack of decision making tools for preparing road maintenance programmes. This results in poor resource allocation and poor utilisation of existing assets. Pavement management systems (PMS) have been developed around the world in order to assist with the pavement management process in a co-ordinated and systematic manner. Some developed countries have derived pavement performance models that are suited to local conditions by setting up long term pavement performance studies. Conversely, most developing countries do not have the resources required to set up similar large-scale field experiments. However, validation …

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Case Studies: In-Situ Rebuilding Of Damaged Rope Drum Shafts Of Ssg Crane And The Repair Of Circumferential Crack Of Cement Kiln By Welding, Joseph Runyoro Dec 2009

Case Studies: In-Situ Rebuilding Of Damaged Rope Drum Shafts Of Ssg Crane And The Repair Of Circumferential Crack Of Cement Kiln By Welding, Joseph Runyoro

Tanzania Journal of Engineering and Technology (TJET)

Material failures in engineering are characterized by unwanted downtime of equipment and require the application of sound engineering principles to rectify the problem so that it does not reoccur. The most widely method for repairing damaged steel structures such as rope drum shaft or cracked cement kiln is by Manual metal arc welding. The equipment mentioned have their main importance that, when they are broken down, they cost a lot of money in lost revenue and affects a lot of people in terms of business and livelihood. The nominal diameter (DN) 240 rope drum shaft was damaged when the roller …

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Modelling The Impact Of Urbanization On Groundwater Using System Dynamic Technique. A Case Study Of Arusha Municipal Well Field In Northeastern Tanzania, Nimzihirwa Kashimbiri Dec 2009

Modelling The Impact Of Urbanization On Groundwater Using System Dynamic Technique. A Case Study Of Arusha Municipal Well Field In Northeastern Tanzania, Nimzihirwa Kashimbiri

Tanzania Journal of Engineering and Technology (TJET)

This paper is concerned with the impact of urbanization in aquifer well-system located in the Municipal area of Arusha city, Tanzania. A system dynamic (SD) model was built under VENSIM PLE workbench from twenty-five years (1978-2003) physical and non-physical data to simulate their interactions and relations. This involved use of mathematics ideas and concepts in studying the physical and non – physical components separately, and finally putting them together in new form (model) and study their relations. After model was found to be structurally complete and simulate properly by using the model and unit check tool of VENSIMPLE, parametric calibration …

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The Influence Of Branches In The Performance Of Power-Line Communication Systems That Use Mc-Coma With Reed Solomon Coding, Emmanuel Felix Dec 2009

The Influence Of Branches In The Performance Of Power-Line Communication Systems That Use Mc-Coma With Reed Solomon Coding, Emmanuel Felix

Tanzania Journal of Engineering and Technology (TJET)

Power-line network is proposed as an infrastructure for Information and Communications Technologies (ICTs)
services provision. However, there are a number of factors that contribute greatly to power-line communication performance degradation. These include number of branches that can be added or removed from the power- line network, lengths of the branch lines, loading etc. It has been pointed out that the number of branches is one of the factors that affects power-line performance to a certain extent. In this paper the influence of number of branches on the performance of Broadband Power-line communication (BPLC) that uses MC- CDMA modulation scheme with …

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A Systemic Framework For Implementation Of Tqm Programmes, Emanuel Mjema Dec 2009

A Systemic Framework For Implementation Of Tqm Programmes, Emanuel Mjema

Tanzania Journal of Engineering and Technology (TJET)

The purpose of this paper is to present a systemic framework for implementation of TQM program in a manufacturing organisation that produces motor vehicle components in Port Elizabeth - South Africa. The approach used included conceptualisation of the systemic framework and then involvement of the stakeholders in adding scenarios to be considered in the design and implementing the framework in the real field. The findings obtained during the implementation of the systemic framework established that reduction of scrap rate, reduction of production costs, reduction of cycle time and employee motivation could be achieved through the implementation of a Systemic Framework …

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Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung Dec 2009

Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung

Journal of Marine Science and Technology–Taiwan

A fuzzy gain scheduling proportional controllers that exhibits the improved performance than the conventional linear fixed gain controller having input saturation is proposed in this paper. We proposed an adaptive anti-windup control system in which the gain of a proportional controller is dynamically tuned by a fuzzy PD system. The methodology employed in the analysis is based on the describing function (DF), which is determined the range of the universal discourse for the output of the fuzzy PD system. Other approaches are the linear quadratic regulator (LQR) method and combined back-calculation and generalized conditioning anti-windup. In this paper, a comparison …

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The Construction Common Product Coding System And Auto Id Technology In Construction, Nai-Hsin Pan Dec 2009

The Construction Common Product Coding System And Auto Id Technology In Construction, Nai-Hsin Pan

Journal of Marine Science and Technology–Taiwan

Automatic data identification (Auto ID) technology such as bar code has grown rapidly in various industries. During the last couple of years, a small number of construction companies have also started to implement Auto ID technologies for a limited number of applications. The focus of these applications has primarily been limited to the internal operations of a few larger companies. One of the major barriers to adopt modern Auto ID technologies in the construction industry is the lack of Construction Common Product Code System (CCPCS). The main objective of this research is to investigate the problems created by inadequate CCPCS …

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