159 research outputs found
On Unfair Permutations
No full textIslak, Umit/0000-0003-4281-5171In this paper we study the inverse of so-called unfair permutations. Our investigation begins with comparing this class of permutations with uniformly random permutations, and showing that they behave very much alike in case of locally dependent random variables. As an example of a globally dependent statistic we use the number of inversions, and show that this statistic satisfies a central limit theorem after proper centering and scaling. (C) 2018 Elsevier B.V. All rights reserved.TUBITAK [113F059]; Scientific and Research Council of Turkey [TUBITAK-117C047]The author C. P. has been supported by TUBITAK within the project 113F059 entitled "The conjecture of Mazur-Tate-Teitelbaum, CM elliptic curves and applications" as a postdoctoral researcher at Koc University. The author U.I. is supported by the Scientific and Research Council of Turkey [TUBITAK-117C047]. Parts of this paper were completed at the Nesin Mathematics Village, the authors would like to thank Nesin Mathematics Village for their kind hospitality. Also, the authors would like to thank an anonymous referee who detected some errors in original manuscript, and whose comments improved the paper significantly
Low-cost, highly efficient, and tunable ultrafast laser technology based on directly diode-pumped Cr:Colquiriites
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 335-352).This doctoral project aims to develop robust, ultra low-cost (150) as the pump source, we have obtained continuous-wave (cw) output powers >250-mW with slope efficiencies >50%. Record cw tuning ranges were demonstrated for Cr:LiSAF (775-1042 nm), Cr:LiSGaF (777-977 nm), and Cr:LiCAF (754-871 nm). For femtosecond pulse generation, semiconductor saturable absorber mirrors (SESAMs/SBRs) were developed, which were used to initiate and sustain mode-locking. Typical performance was ~25-100 fs pulses, with an optical spectrum in the 770-920 nm range, with ~1-2 nJ of pulse energies from ~100-MHz repetition rate cavities. Record electrical-to-optical conversion efficiencies of ~10% were demonstrated in the cw mode-locked regime. A mode-locked tuning range of 767-817 nm, with ~130-fs long pulses was obtained by using Cr:LiCAF as gain medium. With the Cr:LiSAF gain medium, using regular SESAMs/SBRs centered around 800 nm, 850 nm, and 910 nm, mode-locked tuning ranges of 803-831 nm, 828-873 nm, and 890-923 nm were demonstrated, respectively. By using a broadband oxidized SESAM/SBR, a record tuning range of 800-905 nm was demonstrated with ~150-fs long pulses. Using an extended cavity Cr:LiCAF laser, pulse energies >15-nJ with peak powers exceeding 100-kW were obtained. We performed the first cavity-dumping experiments with a Cr:Colquiriite laser and demonstrated pulse energies >100-nJ, and peak powers approaching MW level, at repetition rates up to 50-kHz. Cr:LiCAF gain media were also pumped by single-emitter multimode diodes, where we obtained >2-W output power in cw operation, and ~100-fs pulses with 390-mW of average power at a repetition rate of 140 MHz in cw mode-locked operation. As an example application area for this low cost technology, we performed multiphoton microcopy experiments with a single-mode diode-pumped Cr:LiCAF laser. We also performed attosecond-resolution timing jitter characterization experiments of the femtosecond Cr:LiSAF laser, and measured a record-low upper limit for the integrated timing jitter of the Cr:LiSAF laser (137-attoseconds in 10 kHz-10 MHz range).by Umit Demirbas.Ph.D
Ebû Şekûr es-Sâlimî’nin Hilâfete İlişkin Görüşleri
No full textThe Caliphate/Imamate was one of the most important issues among the Muslims following the death of the Prophet. This issue, especially with Shia, has been moved from the political area to the theological area. As a matter of fact, the Sunni theologians probably with the influence of Shiite scholars, included the Imama/Khilafa issue in their kalami issued and gave place to it in their works. One of them is the theologian Abu Shakur al-Salimi (d. after 460/1068) from Samarkand region. In the Hanafi biographical books, there is not much information about the life of Abu Shakur. On the basis of some of the information given in his own work al-Tamhid fi bayan at-taw id, it is estimated that Abu Shakur was born at first half of 5th century of the Hegirah (11th century). In this work, Abu Shakur mainly dealt with the following issues: the mind/reason, the existence of Allah, the oneness of Allah, the names and attributes of Allah, miracles, revelation, the Miraculousness of Qur'an, literal kalam-spiritual kalam, the conditions of faith, caliphate and imamate, Ahl as-Sunnah, Ahl al-Bid 'ah. As the title implies, in this paper, we will try to put forward the views of Abu Shakur al-Salimi on Khilafa/Imamate issue based on his work al-Tamhid fi bayan at-taw id. In this context, the views of the author about the meritorious virtues of the Companions of the Prophet will be pointed out. In addition, the criticism of Abu Shakur al-Salimi regarding the Shia's understanding of imamate will be examined. These issues, which the author deals with, are probably among the topics discussed in the region during his period
Building Information Modelling: essentials and issues: The need to Integrate BIM and Geoinformation
No full textIn the construction industry, business relationships are often short-term and one-off. There are many unique processes and activities. The resulting complexity and fragmentation may obstruct quick and effective exchange and integration of information and thus hamper project progress. Building Information Modelling (BIM) aims at preventing mismatches in information exchange between the many stakeholders. Although BIM has come a long way in this respect, there are still challenges to overcome. The authors explain the essentials of BIM and discuss issues
Towards dynamically stable gait of an 8 degrees of freedom exoskeleton through predictive forward dynamics simulation
No full textThe main form of mobility for paraplegic patients is by wheelchair. However, not moving the legs comes with adverse health effects. Exoskeletons are one solution to get these patients walking again. One of the aims of exoskeleton research is the complete restoration of locomotion for paraplegic patients. The achieved gait must be stable, safe and comfortable for the patients. Most research goes into exoskeleton devices which require the use of balancing aids. In the form of crutches, these aids help the exoskeleton users to maintain stability. One of the goals is to eliminate the reliance on balance aids and let the robot do most work. Until now only two exoskeletons are able to achieve autonomous dynamically stable gait. The gait generation algorithms used in these device are based on inverse dynamics. trajectories are calculated and closely tracked. The main challenges of inverse dynamics control algorithms are slow and static movement, balance recovery issues or computational complexity. In this research the aim is to achieve autonomous walking without balance aids. The Project MARCH exoskeleton is taken as an example in this case study. This device has 4 actuated degrees of freedom per leg. The exoskeleton is modelled in OpenSim. Using predictive forward dynamic simulations, a gait algorithm is implemented and evaluated. The reflex-based control algorithm is based on proportional-derivative controllers. This control algorithm is implemented in SCONE and is optimized using the Covariance Matrix Adaptation - Evolution Strategy method. A second simulation experiment uses the same method to achieve standing balance. After optimization of the control algorithm, dynamically stable gait patterns emerge. The exoskeleton model shows limit cycle behaviour and is able to walk for at least 30 seconds at a speed of 0.7 m/s. The controller can optimized to reject perturbations up to 300 N for 0.1 s. The emerging gait pattern shows two features, which complicate the implementation in the real exoskeleton. The model shows a back-heel rotation during stance phase and hits the joint limits during the liftoff phase. Standing balance is also achieved by a different controller. This research serves as a proof of concept on using SCONE (or more general, predictive forward dynamic simulations) to simulate and test an autonomous exoskeleton. The algorithms are completely feedback controlled require no predefined trajectories. Certain features seen in the emerging gait patterns remain to be resolved. This work demands more research to prevent back-heel rotation, to avoid approaching the joint limits and model the toe-off more adequately in order to reduce the peak torque. Furthermore, interesting research can be done on a randomized perturbation rejection and on how to model the inelastic collision at the joint-ends properly as well as on making a comparison between the gait patterns presented in this research and the patterns currently used in the exoskeleton. Only if these challenges are addressed, the gait algorithm becomes eligible to employ in a real exoskeleton
Foundational SOA Patterns for Complex Information Models
No full textIn domains where detailed semantic information coupled with detailed geometric representations is of key importance, such as city modelling, construction, aircraft industry, ship production and so on, information models that represent these domains are usually of a complex structure. This chapter starts by summarizing design principles of service orientation, and later provides 10 service-oriented architecture (SOA) patterns for managing complex information models. The chapter provides patterns to facilitate the management of complex information models. Generalized service-oriented architectural approaches covering complex information models are presented. BIM-specific SOA patterns are presented in Chaps. 6 and 7. © The Author(s) 2015
Summary and Future Outlook
No full textThere are significant advantages provided by the patterns presented, including provision of client-independent and lightweight software architectures by making use of loosely coupled nature of RESTful Web services and message brokers. The integration of Internet of things (IoT) and building information models (BIMs), consuming information acquired from both resources, provides various opportunities for different domains ranging from city management to construction management and emergency response. This chapter provides a summary of the book contents and underlines the opportunities provided by integration of information from BIM and IoT elements. © The Author(s) 2015
Advanced SOA Patterns for Building Information Models
No full textTwo styles of Web services exist today: Simple Object Access Protocol (SOAP) and REST. Representational State Transfer (REST) is often preferred over the more heavyweight SOAP because REST does not leverage as much bandwidth. REST’s decoupled architecture makes it a popular building style for cloud-based APIs, such as those provided by Amazon, Microsoft and Google. This chapter starts with providing technical information about RESTful Web services. Following this, RESTful design patterns for facilitating BIM-based software and Web service architectures are presented. © The Author(s) 2015
- …
