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Articles 6631 - 6660 of 10319
Full-Text Articles in Physical Sciences and Mathematics
Power Efficient Linear Transmitters Using Sigma-Delta Modulation With Switching Amplifiers, Tayfun Nesimoglu
Power Efficient Linear Transmitters Using Sigma-Delta Modulation With Switching Amplifiers, Tayfun Nesimoglu
Turkish Journal of Electrical Engineering and Computer Sciences
In conventional envelope elimination and restoration transmitters, the envelope information of the carrier is reconstructed by modulating the supply voltage of the switching amplifier. In this paper, it is shown that the supply voltage modulation introduces nonlinearity and reduces the average power efficiency of the transmitter. Here, novel transmitter architectures using sigma-delta--modulated carrier signals are proposed to overcome these shortcomings. The proposed architecture's and conventional envelope elimination and restoration transmitter's linearity and efficiency performances are compared at various oversampling rates and signal bandwidths. It is demonstrated that the proposed architectures may provide better linearity and efficiency than conventional envelope elimination …
Adaptive Control Of A Time-Varying Rotary Servo System Using A Fuzzy Model Reference Learning Controller With Variable Adaptation Gain, Ömer Aydoğdu, Özdemi̇r Alkan
Adaptive Control Of A Time-Varying Rotary Servo System Using A Fuzzy Model Reference Learning Controller With Variable Adaptation Gain, Ömer Aydoğdu, Özdemi̇r Alkan
Turkish Journal of Electrical Engineering and Computer Sciences
The constant parameters in a conventional fuzzy controller lead to a poor performance for time-varying systems. In this study, a fuzzy model reference learning controller (FMRLC) with a newly defined variable adaptation gain is designed and implemented in the adaptive fuzzy control of a time-varying rotary servo (TVRS) system. In the design of the FMRLC, a knowledge-base modification algorithm with variable adaptation gain is used instead of a fuzzy relation table. Hence, it is provided that the learning and adaptation mechanism continuously updates the knowledge base of the adaptive fuzzy controller against any parameter variations, such as changing loads. By …
Optimized Operation And Maintenance Costs To Improve System Reliability By Decreasing The Failure Rate Of Distribution Lines, Hamed Hashemi Dezaki, Seyed Hossein Hosseinian, Hossein Askarian Abyaneh, Seyed Mohammad Mousavi Agah
Optimized Operation And Maintenance Costs To Improve System Reliability By Decreasing The Failure Rate Of Distribution Lines, Hamed Hashemi Dezaki, Seyed Hossein Hosseinian, Hossein Askarian Abyaneh, Seyed Mohammad Mousavi Agah
Turkish Journal of Electrical Engineering and Computer Sciences
Improving distribution system reliability has received a great deal of attention in recent years. Because of the limitation in expected budgets, it is desirable to determine the most efficient strategy to improve system reliability. This paper proposes a novel method to determine the optimized operation and maintenance costs in order to decrease the failure of system components. The proposed objective function includes the average system frequency interruption index (ASIFI) value. To achieve the best strategy to decrease failures of system components, it is necessary to find the minimum value of the objective function, considering the constraints of operation and maintenance …
A Low-Voltage And Low-Power Sinh-Domain Universal Biquadratic Filter For Low-Frequency Applications, Farooq Khanday, Nisar Shah
A Low-Voltage And Low-Power Sinh-Domain Universal Biquadratic Filter For Low-Frequency Applications, Farooq Khanday, Nisar Shah
Turkish Journal of Electrical Engineering and Computer Sciences
Sinh-domain CMOS filters have favorable properties, such as a wide dynamic range at low supply voltage, compactness, linearity, and low power consumption. These properties are becoming increasingly important for biomedical applications that require extremely low-power dissipation and neuromorphic circuits that attempt to reproduce the biophysics of biological neurons and synapses. In this paper, a low-voltage sinh-domain universal biquadratic filter circuit is introduced. The circuit, aside from permitting the independent adjustment of pole frequency (\omega_0) and the quality factor (Q), is free from matching conditions, capable of absorbing the shunt parasitic capacitances, amenable for monolithic integration, and composed of merely a …
Control Of Diesel Engines Mounted On Vehicles In Mobile Cranes Via Can Bus, Muci̇z Özcan, Hi̇dayet Günay
Control Of Diesel Engines Mounted On Vehicles In Mobile Cranes Via Can Bus, Muci̇z Özcan, Hi̇dayet Günay
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, the aim was to lift loads that required more force using the infrastructure of existing vehicles. To this end, a truck-mounted diesel engine was selected to be used in mobile crane applications. A control system was designed and implemented to obtain the appropriate hydraulic force by accessing the diesel engine with a controller area network bus via an electronic control unit (ECU). For this purpose, hydraulic pumps to be used to operate the crane were mounted on the selected mobile diesel engine with an ECU. Firms that manufacture cranes in the world produce cranes with infrastructure. This …
Design Of Information Retrieval Experiments: The Sufficient Topic Set Size For Providing An Adequate Level Of Confidence, Beki̇r Taner Di̇nçer
Design Of Information Retrieval Experiments: The Sufficient Topic Set Size For Providing An Adequate Level Of Confidence, Beki̇r Taner Di̇nçer
Turkish Journal of Electrical Engineering and Computer Sciences
In the current design of information retrieval (IR) experiments, a sample of 50 topics is generally agreed to be sufficient in size to perform dependable system evaluations. This article presents the detailed and formal explanation of how the second fundamental theorem of probability, the central limit theorem, can be used for the estimation of the sufficient size of a topic sample. The research performed in this article, using past Text Retrieval Conference data, reveals that, on average, 50 topics will be sufficient to provide a confidence level at or above 95% if the null hypothesis of an equal population mean …
A Novel Dynamic Bandwidth Selection Method For Thinning Noisy Point Clouds, Mehmet Öztürk, Zeynep Hasirci
A Novel Dynamic Bandwidth Selection Method For Thinning Noisy Point Clouds, Mehmet Öztürk, Zeynep Hasirci
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, we propose a dynamic bandwidth selection method for thinning noisy point clouds into curves. Due to the nonhomogeneous distribution of noise or varying curvature of the data, the thinning procedure requires a dynamically adjusted bandwidth along the curve. On the other hand, the selected local region must be sorted along a suitable direction vector for local curve fitting purposes. The contribution of this paper to the field is 2-folded: first, a normalized eigenvalue analysis-based method is used to determine the best local bandwidth. The second task is getting a good regression line of the local region for …
Stopping Spam With Sending Session Verification, Ahmet Baran
Stopping Spam With Sending Session Verification, Ahmet Baran
Turkish Journal of Electrical Engineering and Computer Sciences
Spam has become one of the most significant problems for Internet communication and users today. The traditional filtering methods and signature-based spam blocking systems that have come into prominence recently fall short, as statistics demonstrate that spam further mounts up day after day. In this study, a new method is recommended to block spam mails. In this recommended method, a mail sending session is verified during mail envelope communication by adding small attachments to the simple mail transfer protocol, so spam mails can be blocked before leaving the sender domain or relay machine. Additionally, hijacked user accounts are able to …
Optimal Placement And Sizing Of Distributed Generations In Distribution Systems For Minimizing Losses And Thd_V Using Evolutionary Programming, Aida Fazliana Abdul Kadir, Azah Mohamed, Hussain Shareef, Mohd Zamri Che Wanik
Optimal Placement And Sizing Of Distributed Generations In Distribution Systems For Minimizing Losses And Thd_V Using Evolutionary Programming, Aida Fazliana Abdul Kadir, Azah Mohamed, Hussain Shareef, Mohd Zamri Che Wanik
Turkish Journal of Electrical Engineering and Computer Sciences
Growing concerns over environmental impacts, improvement of the overall network conditions, and rebate programs offered by governments have led to an increase in the number of distributed generation (DG) units in commercial and domestic electric power production. However, a large number of DG units in a distribution system may sometimes contribute to high levels of harmonic distortion, even though the emission levels of the individual DG units comply with the harmonic standards. It is known that the nonoptimal size and nonoptimal placement of DG units may lead to high power losses, bad voltage profiles, and harmonic propagations. Therefore, this paper …
Ssr Mitigation With Sssc Thanks To Fuzzy Control, Seyed Mohammad Hassan Hosseini, Hadi Samadzadeh, Javad Olamaei, Murtaza Farsadi
Ssr Mitigation With Sssc Thanks To Fuzzy Control, Seyed Mohammad Hassan Hosseini, Hadi Samadzadeh, Javad Olamaei, Murtaza Farsadi
Turkish Journal of Electrical Engineering and Computer Sciences
This paper deals with the capability of a static synchronous series compensator (SSSC) to attenuate the subsynchronous resonance (SSR). Two well-known controllers are designed, namely a conventional damping controller (CDC) and fuzzy logic damping controller (FLDC). These 2 damping controllers are added to a main control loop of a SSSC operating as a SSR damping controller. It should be noted that, to optimize the parameters of the CDC, a versatile optimization technique is implemented, namely particle swarm optimization (PSO). A comprehensive comparison between the 2 control methods is carried out for different operational conditions. To observe the superior performance of …
Hybrid Spr Algorithm To Select Predictive Genes For Effectual Cancer Classification, Aruna Sundaram, Nandakishore Lellapalli Venkata, Rajagopalan Sarukai Parthasarathy
Hybrid Spr Algorithm To Select Predictive Genes For Effectual Cancer Classification, Aruna Sundaram, Nandakishore Lellapalli Venkata, Rajagopalan Sarukai Parthasarathy
Turkish Journal of Electrical Engineering and Computer Sciences
Designing an automated system for classifying DNA microarray data is an extremely challenging problem because of its high dimension and low amount of sample data. In this paper, a hybrid statistical pattern recognition algorithm is proposed to reduce the dimensionality and select the predictive genes for the classification of cancer. Colon cancer gene expression profiles having 62 samples of 2000 genes were used for the experiment. A gene subset of 6 highly informative genes was selected by the algorithm, which provided a classification accuracy of 93.5%.
A Video-Based Eye Pupil Detection System For Diagnosing Bipolar Disorder, Gökay Akinci, Edi̇z Polat, Orhan Murat Koçak
A Video-Based Eye Pupil Detection System For Diagnosing Bipolar Disorder, Gökay Akinci, Edi̇z Polat, Orhan Murat Koçak
Turkish Journal of Electrical Engineering and Computer Sciences
Eye pupil detection systems have become increasingly popular in image processing and computer vision applications in medical systems. In this study, a video-based eye pupil detection system is developed for diagnosing bipolar disorder. Bipolar disorder is a condition in which people experience changes in cognitive processes and abilities, including reduced attentional and executive capabilities and impaired memory. In order to detect these abnormal behaviors, a number of neuropsychological tests are also designed to measure attentional and executive abilities. The system acquires the position and radius information of eye pupils in video sequences using an active contour snake model with an …
Flow Velocity Measurement And Analysis Based On Froth Image Sift Features And Kalman Filter For Froth Flotation, Jinping Liu, Weihua Gui, Zhaohui Tang
Flow Velocity Measurement And Analysis Based On Froth Image Sift Features And Kalman Filter For Froth Flotation, Jinping Liu, Weihua Gui, Zhaohui Tang
Turkish Journal of Electrical Engineering and Computer Sciences
The flow velocity of flotation froth involves important information about the concentrate grade and the mineral recovery. It is significant to maintain the flow velocity of the froth at proper levels to achieve a good production performance in the machine vision-based process monitoring and control. However, the accurate velocity field measurement for the heavily deformed and seriously fragile froth bubbles is still a great challenge. Scale-invariant feature transform (SIFT) feature-based image matching provides an effective registration method for deformed objects, but most of the processing time would be wasted on the feature extraction and matching in irrelevant regions of the …
Approximate Groups Iii: The Unitary Case, Emmanuel Breuillard, Ben Green
Approximate Groups Iii: The Unitary Case, Emmanuel Breuillard, Ben Green
Turkish Journal of Mathematics
By adapting the classical proof of Jordan's theorem on finite subgroups of linear groups, we show that every approximate subgroup of the unitary group U_n(C) is almost abelian.
On Some New Inequalities For Convex Functions, Mevlüt Tunç
On Some New Inequalities For Convex Functions, Mevlüt Tunç
Turkish Journal of Mathematics
In the present paper we establish some new integral inequalities analogous to the well known Hadamard's inequality by using a fairly elementary analysis.
A Generalization Of Banach's Contraction Principle For Some Non-Obviously Contractive Operators In A Cone Metric Space, Yingxin Guo
Turkish Journal of Mathematics
This paper investigates the fixed points for self-maps of a closed set in a space of abstract continuous functions. Our main results essentially extend and generalize some fixed point theorems in cone metric spaces. An application to differential equations is given.
Geodesicity And Isoclinity Properties For The Tangent Bundle Of The Heisenberg Manifold With Sasaki Metric, Simona Luiza Druta, Paola Piu
Geodesicity And Isoclinity Properties For The Tangent Bundle Of The Heisenberg Manifold With Sasaki Metric, Simona Luiza Druta, Paola Piu
Turkish Journal of Mathematics
We prove that the horizontal and vertical distributions of the tangent bundle with the Sasaki metric are isocline, the distributions given by the kernels of the horizontal and vertical lifts of the contact form \omega on the Heisenberg manifold (H_3,g) to (TH_3,g^S) are not totally geodesic, and the distributions F^H=L(E_1^H,E_2^H) and F^V=L(E_1^V,E_2^V) are totally geodesic, but they are not isocline. We obtain that the horizontal and natural lifts of the curves from the Heisenberg manifold (H_3,g), are geodesics on the tangent bundle endowed with the Sasaki metric (TH_3,g^s), if and only if the curves considered on the base manifold are …
Ion Probe U-Pb Dating Of The Central Sakarya Basement: A Peri-Gondwana Terrane Intruded By Late Lower Carboniferous Subduction/Collision-Related Granitic Rocks, Petek Ayda Ustaömer, Ti̇mur Ustaömer, Alastair Robertson
Ion Probe U-Pb Dating Of The Central Sakarya Basement: A Peri-Gondwana Terrane Intruded By Late Lower Carboniferous Subduction/Collision-Related Granitic Rocks, Petek Ayda Ustaömer, Ti̇mur Ustaömer, Alastair Robertson
Turkish Journal of Earth Sciences
Ion probe dating is used to determine the relative ages of amphibolite-facies meta-clastic sedimentary rocks and crosscutting granitoid rocks within an important 'basement' outcrop in northwestern Turkey. U-Pb ages of 89 detrital zircon grains separated from sillimanite-garnet micaschist from the Central Sakarya basement terrane range from 551 Ma (Ediacaran) to 2738 Ma (Neoarchean). Eighty five percent of the ages are 90-110% concordant. Zircon populations cluster at ~550-750 Ma (28 grains), ~950-1050 Ma (27 grains) and ~2000 Ma (5 grains), with smaller groupings at ~800 Ma and ~1850 Ma. The first, prominent, population (late Neoproterozoic) reflects derivation from a source area …
Petrogenesis Of Late Cretaceous Adakitic Magmatism In The İstanbul Zone (Çavuşbaşı Granodiorite, Nw Turkey), Sabah Yilmaz Şahi̇n, Namik Aysal, Yildirim Güngör
Petrogenesis Of Late Cretaceous Adakitic Magmatism In The İstanbul Zone (Çavuşbaşı Granodiorite, Nw Turkey), Sabah Yilmaz Şahi̇n, Namik Aysal, Yildirim Güngör
Turkish Journal of Earth Sciences
The Çavuşbaşı granodiorite intrudes Ordovician sedimentary rocks in the western part of the İstanbul Zone (NW Turkey). The intrusion is made up mainly of granodiorite, and subordinate tonalite and quartz diorite, and has a granular texture and some special mixing textures such as antirapakivi, blade-shaped biotite, acicular apatite, spongy cellular dissolution/melting plagioclase textures. The main mafic minerals are hornblende and biotite. U-Pb in-situ dating of zircons from two samples via SHRIMP yielded weighted age values of ~68 Ma, suggesting emplacement during the Late Cretaceous. Geochemically the Çavuşbaşı granodiorite resembles adakites with high Sr/Y and La/Yb ratios, low Y and HREE …
Early Oligocene Continental Climate Of The Palaeogene Basin (Hungary And Slovenia) And The Surrounding Area, Boglarka Erdei, Torsten Utescher, Lilla Hably, Julia Tamás, Anita Roth-Nebelsick, Michaela Grein
Early Oligocene Continental Climate Of The Palaeogene Basin (Hungary And Slovenia) And The Surrounding Area, Boglarka Erdei, Torsten Utescher, Lilla Hably, Julia Tamás, Anita Roth-Nebelsick, Michaela Grein
Turkish Journal of Earth Sciences
This paper concentrates on the Early Oligocene palaeoclimate of the southern part of Eastern and Central Europe and gives a detailed climatological analysis, combined with leaf-morphological studies and modelling of the palaeoatmospheric CO_2 level using stomatal and \delta^1^3C data. Climate data are calculated using the Coexistence Approach for Kiscellian floras of the Palaeogene Basin (Hungary and Slovenia) and coeval assemblages from Central and Southeastern Europe. Potential microclimatic or habitat variations are considered using morphometric analysis of fossil leaves from Hungarian, Slovenian and Italian floras. Reconstruction of CO_2 is performed by applying a recently introduced mechanistic model. Results of climate analysis …
Palaeoclimate Estimates For Selected Leaf Floras From The Late Pliocene (Reuverian) Of Central Europe Based On Different Palaeobotanical Techniques, Christine Thiel, Stefan Klotz, Dieter Uhl
Palaeoclimate Estimates For Selected Leaf Floras From The Late Pliocene (Reuverian) Of Central Europe Based On Different Palaeobotanical Techniques, Christine Thiel, Stefan Klotz, Dieter Uhl
Turkish Journal of Earth Sciences
To provide quantitative palaeoclimate estimates based on different palaeobotanical techniques for three contemporaneous Pliocene leaf floras, we applied the Coexistence Approach (CoA), leaf margin analysis (LMA), the Climate Leaf Analysis Multivariate Program (CLAMP) and the European Leaf Physiognomic Approach (ELPA). Furthermore, we compared recently published estimates from an additional locality with our data. The leaf physiognomic techniques yield lower mean annual temperatures than the CoA, which is most likely caused by taphonomic biases. Due to these potential biases we are in favour of the CoA as the most reliable method, and its palaeotemperature estimates show similar temperatures for all localities. …
Palaeoclimate Evolution In Siberia And The Russian Far East From The Oligocene To Pliocene – Evidence From Fruit And Seed Floras, Svetlana Popova, Torsten Utescher, Dmitry Gromyko, Angela Bruch, Volker Mosbrugger
Palaeoclimate Evolution In Siberia And The Russian Far East From The Oligocene To Pliocene – Evidence From Fruit And Seed Floras, Svetlana Popova, Torsten Utescher, Dmitry Gromyko, Angela Bruch, Volker Mosbrugger
Turkish Journal of Earth Sciences
The Cenozoic continental deposits of Western Siberia, Eastern Siberia and the Russian Far East are best described on the basis of carpological records. The palaeoclimate evolution has been reconstructed quantitatively (Coexistence Approach) providing inferred data on temperature, precipitation and the mean annual range of these parameters. Climate curves document the transition from very warm and humid conditions in the Late Oligocene via the Middle Miocene Climatic Optimum to a cool temperate climate during the Pliocene. Compared with other time intervals the Miocene climate is the most comprehensively reconstructed. For the Middle Miocene the Siberian and Far Eastern data are combined …
Palaeoclimatic Estimates For The Late Pliocene Based On Leaf Physiognomy From Western Yunnan, China, Sanping Xie, Sun Bainian, Jinyu Wu, Zhicheng Lin, Defei Yan, Liang Xiao
Palaeoclimatic Estimates For The Late Pliocene Based On Leaf Physiognomy From Western Yunnan, China, Sanping Xie, Sun Bainian, Jinyu Wu, Zhicheng Lin, Defei Yan, Liang Xiao
Turkish Journal of Earth Sciences
Based on leaf physiognomy of the Late Pliocene Tuantian megaflora from the Mangbang Formation of Tengchong County in western Yunnan, a quantitative reconstruction of palaeoclimate was performed with Leaf Margin Analysis (LMA) methodology and the Climate-Leaf Analysis Multivariate Program (CLAMP). The latter produced the following parameters: mean annual temperature (MAT) from 17.2 to 17.7°C; warmest month mean temperature (WMMT) from 25 to 25.5°C; coldest month mean temperature (CMMT) from 9.5 to 10.8°C; length of growing season (GRS) from 9.5 to 9.7 months; growing season precipitation (GSP) from 1834.3 to 1901.2 mm; mean monthly growing season precipitation (MMGSP) from 222.4 to …
Silurian Graptolite, Conodont And Cryptospore Biostratigraphy Of The Gülüç Section In Ereğli, Zonguldak Terrane, Nw Anatolia, Turkey, Valeri Sachanski, Mehmet Cemal Göncüoğlu, Iskra Lakova, Ilina Boncheva, Gülnur Saydam-Demi̇ray
Silurian Graptolite, Conodont And Cryptospore Biostratigraphy Of The Gülüç Section In Ereğli, Zonguldak Terrane, Nw Anatolia, Turkey, Valeri Sachanski, Mehmet Cemal Göncüoğlu, Iskra Lakova, Ilina Boncheva, Gülnur Saydam-Demi̇ray
Turkish Journal of Earth Sciences
The studied Gülüç section of the Silurian Fındıklı Formation is situated on the western bank of Gülüç Creek in Ereğli, NW Anatolia, Turkey, in the eastern part of the Zonguldak Terrane. The Gülüç section consists of 3 sedimentary packages: greenish grey limy siltstones, 5-7 m thick (1), overlain by an irregular alternation of black shales and clayey limestones, about 15 m thick (2), and a 6-7 m thick succession of mainly siltstones and sandy limestones (3). A combined biostratigraphy based upon graptolites, cryptospores and conodonts indicates that Package 1 is of Llandovery (Rhuddanian, Aeronian and/or early Telychian) age, Package 2 …
Symmetry And The Order Of Events In Time. The Asymmetrical Order Of Events In Time In A Reversible Energy Converter, Ben-Zion Ginzburg, Randy Wayne
Symmetry And The Order Of Events In Time. The Asymmetrical Order Of Events In Time In A Reversible Energy Converter, Ben-Zion Ginzburg, Randy Wayne
Turkish Journal of Physics
The positive increase of entropy that occurs in irreversible processes has always served as a criterion for distinguishing the past from the future. The unerring ability of the Second Law of Thermodynamics to predict the order of events in time based on a change of entropy in macroscopic systems has led to the concept of the thermodynamical arrow of time. In this paper we analyze a cyclical reversible energy converter, in which thermal energy is converted into useful work without any net change of entropy. While it is usually assumed that time is an outsider in the equations of reversible …
Symmetry And The Order Of Events In Time. A Proposed Identity Of Negative Mass With Antimatter, Randy Wayne
Symmetry And The Order Of Events In Time. A Proposed Identity Of Negative Mass With Antimatter, Randy Wayne
Turkish Journal of Physics
In another paper in this series, we developed a symmetrical theory of mass which describes how systems of positive mass and negative mass will respond to an input of thermal energy. A system composed of positive mass or negative mass will respond to an input of thermal energy in opposite ways. For example, if a system composed of positive mass expands in response to radiation from a hot body, a system composed of negative mass will contract. Likewise, if the system composed of positive mass contracts when brought in communication with a cold body, a system composed of negative mass …
Exactly Solvable Potentials From Decemvirate Power Potential, Nilamoni Saikia
Exactly Solvable Potentials From Decemvirate Power Potential, Nilamoni Saikia
Turkish Journal of Physics
A transformation method is presented which consist of a coordinate transformation and a functional transformation that allow generation of exact analytic bound state solutions of the Schrodinger Green's function equation. The method proposed here, which involves the generation of an exact analytic solution from solvable decemvirate power potential within the framework of Green's functions technique, makes it possible to generate a number of solved quantum systems for original quantum systems with multi-term potentials. The generated quantum systems are in general energy dependent with a single normalized eigenstate. A method has been devised to convert a subset of the generated quantum …
The Influence Of Confinements On The Photon Flux Spectra In Amorphous Silicon Quantum Dots, Moafak Cadim Abdulrida, Nidhal Moosa Abdul-Ameer, Shatha Mohammad Abdul-Hakeem
The Influence Of Confinements On The Photon Flux Spectra In Amorphous Silicon Quantum Dots, Moafak Cadim Abdulrida, Nidhal Moosa Abdul-Ameer, Shatha Mohammad Abdul-Hakeem
Turkish Journal of Physics
We have theoretically calculated the photon flux of radiative recombination in amorphous silicon quantum dots (a-SiQDs) at room temperature. These quantum dots have been ranged in their diameter 1 to 4 nm. The convolution of probability density function of deepest energy states of conduction P_C(E) and valence P_V(E) bands within the capture volume was adopted. The behavior of this function can be classified into four regions according to the quantum dot size. The effect of spatial and quantum confinements on the peak value of photon flux must be taken into account. We found that a blue shift is classified by …
Dynamics And Noise Of Fiber-Grating Semiconductor Lasers Affected By The Line-Width Enhancement Factor, Salah Abdulrhmann
Dynamics And Noise Of Fiber-Grating Semiconductor Lasers Affected By The Line-Width Enhancement Factor, Salah Abdulrhmann
Turkish Journal of Physics
This paper numerically investigates the effect of the line-width enhancement factor on the dynamics and the intensity noise of InGaAs/InP lasers pumping in the wavelength of 980 nm at the strong optical feedback limit. The investigation is performed based on an improved time-delay rate equation model of a single-mode laser. The analyses are performed in terms of the temporal trajectory of the laser intensity, bifurcation diagram, relative intensity noise and injection current. The simulation results indicate that the laser, under strong optical feedback, mainly operates in CW, pulsation or chaos operation depending on the line-width enhancement factor and injection current …
Behavior Of Temperature Dependence Of Permeability Curves At Different Stages Of Crystallizations Of Nanocrystalline Fe_{70.5}Cr_3cu_1nb_3si_{13.5}B_9, Saadni Islam, Kazi Hanium Maria, Shamima Choudhury, Mohammad Abdul Hakim, Dilip Kumar Saha
Behavior Of Temperature Dependence Of Permeability Curves At Different Stages Of Crystallizations Of Nanocrystalline Fe_{70.5}Cr_3cu_1nb_3si_{13.5}B_9, Saadni Islam, Kazi Hanium Maria, Shamima Choudhury, Mohammad Abdul Hakim, Dilip Kumar Saha
Turkish Journal of Physics
Nanocrystalline amorphous ribbons of composition Fe_{70.5}Cr_3Cu_1Nb_3Si_{13.5}B_9 prepared by rapid solidification technique have been studied in the present work. Amorphicity of the ribbons has been confirmed by X-ray diffraction. Crystallization temperatures were identified by X-ray diffraction and crystallization products were analyzed by XRD. When annealed below the crystallization temperature, i.e. when the sample is in amorphous state, temperature dependence of permeability curves were characterized by sharp increase of permeability and subsequent fall to lower value near ferro-paramagnetic transition temperature, which is typical Hopkinson effect for soft ferromagnetic single phase material. Under devitrification, when the sample is in a two phase state, …