Collisional Effects in Isovector Response Function of Nuclear Matter at Finite Temperature

The dipole response function of nuclear matter at zero and finite temperatures is investigated by employing the linearized version of the extended TDHF theory with a non-Markovian binary collision term. Calculations are carried out for nuclear dipole vibrations by employing the Steinwedel-Jensen model and compared with experimental results for $^{120}Sn$ and $^{208}Pb$.Comment: 14 pages, RevTex, 3 PS figure

Effects of the tensor force on the ground and first 2+2^{+} states of the magic 54^{54}Ca nucleus

The magic nature of the $^{54}$Ca nucleus is investigated in the light of the recent experimental results. We employ both HFB and HF+BCS methods using Skyrme-type SLy5, SLy5+T and T44 interactions. The evolution of the single-particle spectra is studied for the N=34 isotones: $^{60}$Fe, $^{58}$Cr, $^{56}$Ti and $^{54}$Ca. An increase is obtained in the neutron spin-orbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes $^{54}$Ca a magic nucleus candidate. QRPA calculations on top of HF+BCS are performed to investigate the first $J^{\pi}$=$2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the mean-field part of the calculations. The first $2^{+}$ states indicate a subshell closure for both $^{52}$Ca and $^{54}$Ca nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in $^{52}$Ca and $^{54}$Ca nuclei.Comment: 8 pages, 3 figure

Classroom-based professional expertise: a mathematics teacher’s practice with technology

This study examines the classroom practice and craft knowledge underpinning one teacher’s integration of the use of GeoGebra software into mathematics teaching. The chosen teacher worked in an English secondary school and was professionally well regarded as an accomplished user of digital technology in mathematics teaching. Designed in accordance with the Structuring Features of Classroom Practice framework (Ruthven, 2009), the study triangulates evidence from lesson observations and post-lesson interviews to analyse how this teacher’s classroom practice and professional knowledge support the integration of technology. This analysis shows how the teacher managed a number of aspects of classroom teaching related to using GeoGebra such as including technology-mediated tasks aligned with his pedagogical goals, preparing his students to use the technology efficiently, adapting formats for classroom activity and extending his curriculum scripts for the topics studied.The first author thanks the Ministry of National Education of Turkey for supporting her doctoral studies during which this research was undertaken

The distribution and taxonomy of Lissotriton newts in Turkey (Amphibia, Salamandridae)

Two and perhaps three taxa of Lissotriton newt occur in Turkey. Their species status is controversial. The distribution of these taxa and the taxonomic status of each are reviewed and discussed. A database of 128 Turkish Lissotriton localities was compiled and species distribution models were constructed. We reiterate that the presence of L. ( v. ) lantzi in Turkey is disputed and needs confirmation. The range of L. ( v. ) koss - wigi is restricted to north-western Anatolia – given the small global range of this Turkey endemic, a closer look at its conservation status is warranted. The distribution of L. v. schmidtleri covers western Asiatic and European Turkey. The findings support an allopatric distribution of the Turkish Lissotriton species. We reflect on the biological significance of previously reported morphological intermediates between L. ( v. ) kosswigi and L. v. schmidtleri in the light of the recent proposal to recognize kosswigi at the species level. The available data are in line with species status for L. ( v. ) lantzi and L. ( v. ) kosswigi . Although L. v. schmidtleri is a genetically diverged taxon as well, the extent of gene flow with parapatric European Lis - sotriton taxa is as yet unknown

Projections Onto Convex Sets (POCS) Based Optimization by Lifting

Two new optimization techniques based on projections onto convex space (POCS) framework for solving convex and some non-convex optimization problems are presented. The dimension of the minimization problem is lifted by one and sets corresponding to the cost function are defined. If the cost function is a convex function in R^N the corresponding set is a convex set in R^(N+1). The iterative optimization approach starts with an arbitrary initial estimate in R^(N+1) and an orthogonal projection is performed onto one of the sets in a sequential manner at each step of the optimization problem. The method provides globally optimal solutions in total-variation, filtered variation, l1, and entropic cost functions. It is also experimentally observed that cost functions based on lp, p<1 can be handled by using the supporting hyperplane concept

Harmonic Effects on Electromechanical Overcurrent Relays

Elektromekanik aşırı akım koruma röleleri sinüsoidal akım altında çalışmak üzere tasarlanmıştır. Bu rölelerin harmonikli akımda çalışmaları güvenilir değildir. Literatürde harmonikler ve rölelerle ilgili pek çok teorik çalışma bulunmaktadır. Bu makalede, harmoniklerin elektromekanik ters zamanlı aşırı akım rölesinin (TZAAR) çalışmasına etkileri incelenmiş ve TZAAR’nin bozulmuş dalga şekilleri için davranışı deneysel çalışma ile analiz edilmiştir. Deneyde, elektromekanik TZAAR olarak, indüksiyon disk yapısında bir röle kullanılmıştır. Değişik harmonik spektrumlara sahip, sinüsoidal olmayan yük akımları TZAAR’a uygulanmış ve bu yük akımları data toplama kartı ve harmonik analiz programı ile bilgisayar ortamında işlenmiştir. Deney sonuçları gözönüne alındığında, TZAAR’ın çalışma akımı ve çalışma zamanının, sinüsoidal olmayan akımın toplam harmonik distorsiyonu (THD) ile orantılı olarak arttığı görülmüştür. Bu yapıda olan bir rolenin, akımın harmonik içermesi durumunda sistemi güvenli bir şekilde koruyamayacağı sonucu elde edilmiştir.The electromechanical overcurrent protection relays are designed to operate with sinusoidal current. The operation of protective relay with harmonic currents is not reliable. The literature on harmonics and relays covers mostly the theoretical studies. In this paper, the harmonic effects on operation of electromechanical inverse time overcurrent relay (ITOCR) were examined. Not common in existing studies, the behaviour of ITOCR was analysed with laboratory experiments for distorted waveforms. A type of induction disc relay was used as an electromechanical ITOCR in the experiments. The non-sinusoidal load currents that consist of different harmonic spectra were applied to ITOCR and these nonlinear-load currents were processed by a data acquisition card and a harmonic analysis programme in the computer environment. According to the experiment results, the pick up current and the operating time of the ITOCR increase proportionally to the total harmonic distortion (THD) value of the non-sinusoidal current. It is concluded that, this type of relay cannot protect the system reliably due to the harmonic components of current

System of Systems Perspective on Risk: Towards a Unified Concept

Many systems and projects that concern systems engineers, engineering managers, and business managers today can be defined as system of systems (SoS), which are described as ambiguous, uncertain and dynamic, among others. In addition to the traditional view on risk identification, analysis and management, the concept of risk should be considered with respect to these systems of systems. The purpose of this paper is to analyse both fundamental concepts and recent publications in system of systems, business and engineering management, as well as risk analysis, modelling, and management for the purpose of better describing the concept of risk with respect to system of systems. The ultimate goal is to provide engineering and business managers the necessary perspective on the concept of risk and its management for the next generation of systems – including various descriptions of risk and discussion of the relevance of properties of system of systems to sustainable management of risks in engineered systems. To achieve a truly sustainable management of risk, there has to be a change in paradigm from a traditional description of risk to that of a more holistic perspective