Miracle-dz/UniFAR-FTUs huggingface dataset:
Germanium as a platform for semiconductor spintronics

The field of semiconductor spintronics is relatively underdeveloped when compared to its metallic counterpart which has found great success in the computer storage industry in hard disk drive head technology and to a lesser extent non-volatile and robust (M)RAM. The use of semiconductors in spintronics is promising with the ability to modulate spins via a gate controlled spin-orbit interaction allowing for spintronic logic and computation devices. Combining this with dilute ferromagnetic semiconductors, which have been suggested as a base for semiconductor MRAM, it may even be possible to integrate MRAM and logic into a single chip to allow for further miniaturisation of devices. In this thesis we look into the suitability of Ge as a platform for semiconductor spintronics verses other popular alternatives such as Si and GaAs. The first section of this thesis looks at evidence of a strong spin-orbit interaction in low temperature magnetoresistance curves measured in a high mobility (777,000 cm2V-1s-1) Ge 2DHG. Despite the lack of beatings in Subnikov de Haas oscillations, which often serves as an indicator of a strong spin-orbit coupling, weak antilocalisation like behaviour is seen at low fields. The spin splitting energy extracted from the weak antilocalisation and found to be 0.8meV with a Rashba parameter of 3.2x10-28 eVm3. The spin split energy is comparable to other Ge and III-V 2DHGs, however the Rashba parameter is in fact higher, which we believe is attributed to the high level of remote doping. The second section focuses on the treatment of ferromagnet/oxide spin tunnel contacts on Ge deposited by evaporation or sputtering, both of which are common in industrial scale fabrication. Annealing XPS studies are conducted on these contacts to examine the temperature limits at which annealing treatments can be done before contacts degrade. Transition line measurements are also examined to look at the electrical characteristics of the deposited contacts. The final section focuses on the fabrication and measurements of Hanle devices on n-Ge. The extracted spin lifetimes are of the same order as those measured in similarly doped Ge devices, however strong temperature dependencies of both the spin lifetime and spin accumulation signal suggest that the signal measured is strongly influenced by local states within the oxide barrier.
PAM Clustering Aided Android Malicious Apps Detection

The exponential growth of android contrivances has attracted cybercriminals strongly and dramatically. The applications existed in the android market represented an attack surface owing to the lack of security mechanisms applied by the Google play store. Additionally, downloading apps from unofficial sources lead to a further security threat. Any mobile application requests several permissions to access users’ data to run the app. Thus, attackers exploited this feature in compromising users’ sensitive data. This motivated several researchers to investigate security mechanisms to detect Android malware based on this feature utilizing machine learning techniques, particularly classification techniques. However, This research proposes a permission-based android malware detection framework using a clustering algorithm. Further motivation for this research is that large datasets labeling is a tough mission. Therefore, Our work will contribute to android malware detection as well as android apps datasets labeling. PAM (Partitioning Around Medoid) clustering has been exploited for this purpose since its less affected by outliers or other extreme values. The most significant features have been selected as an input to the clustering algorithm to enhance its results. The results depicted that our clustering algorithm was able from grouping our dataset into two categories malevolent and genuine apps. Moreover, our result has been validated by evaluation standard F-Measure, which is counting for 0.86 for 40 attributes subset, while it is 0.88 for 30 features subset. This reveals a good performance level of permission-based android malware detection and android applications datasets labeling into malware and good ware.
Qualitative Comparison Routing Algorithms of MANET Carrying Packet Telephony

— Mobile Ad-hoc Networks are quite different from other wireless networks. The reason behind this difference is the mobile nature of participating nodes. Due to this network configuration keeps on changing and re-routing is frequently required. It has been difficult for researchers to realize Packet Telephony over Mobile Ad-hoc Networks A robust routing algorithm is prerequisite for successful implementation of Packet Telephony over Mobile Ad-hoc Networks. In this work authors are presenting a qualitative comparison of various popular routing algorithms in terms of various QoS parameters. During this work an environment is simulated using ns2 where Packet Telephony is implemented over a Mobile Ad-hoc Network.
AIS-based Vessel Trajectory Prediction for ASV Collision Avoidance

The automotive industry has already taken a big step towards fully autonomous vehicles. This trend is now spreading to the maritime industry with development of autonomous surface vessels (ASVs). A reliable collision avoidance (COLAV) system is essential in this context. In order to avoid collision with other vessels, one must predict the future trajectories of nearby vessels. The constant velocity model (CVM) is the prevailing approach for trajectory prediction in today’s COLAV systems. The main purpose of this thesis is to investigate to what extent it is possible to predict future vessel trajectories based on historical automatic identification system (AIS) data for prediction horizons up to about 15 minutes. A survey of other relevant prediction methods are also presented. Two new, AIS based methods for vessel trajectory prediction are developed and tested: the single point neighbor search (SPNS) method and the neighbor course distribution method (NCDM). Three speed prediction methods are also tested: the straightforward constant speed method, a method using the median speed of the predicted state’s close neighbors (CNs) and lastly a linear transition in predicted time between the two former methods. The SPNS method is compared to a CVM approach and yields significantly better results on curved trajectories, in terms of lower average and median path and trajectory errors. However, a major part of vessels’ transit time is spent on straight line trajectories. The SPNS algorithm shows also good path predicting capabilities on close to straight line trajectories, although the CVM method yields the lowest errors in such environments. The SPNS algorithm outputs a single predicted trajectory which tends to follow the most AIS-dense sea lane ahead. Hence, it does neither facilitate any uncertainty measure nor the possibility to suggest multiple possible route choices. The more computational demanding NCDM algorithm, which outputs multiple predicted trajectories, does better facilitate prediction uncertainty and it is also capable of dividing the predicted trajectories into multiple branching sea lanes. Its predicted positions at certain time instants are clustered with the density-based spatial clustering of applications with noise (DBSCAN) algorithm. The predictions are further statistically evaluated with respect to the distances to the nearest cluster centers. Lastly, a computation time analysis is presented. The computational time is reduced from an earlier version of the algorithm by storing data in a k-d tree. However, the NCDM algorithm with the tested decision parameters is not practically feasible in real-time. Several suggestions to reduce the computation time are given.
CFD analysis of aircraft fuel tanks thermal behaviour

This work is carried out within the FP7 European research project TOICA (Thermal Overall Integrated Conception of Aircraft, http://www.toica-fp7.eu/). One of the tasks foreseen for the TOICA project is the analysis of fuel tanks as possible heat sinks for future aircrafts. In particular, in the present paper, commercial regional aircraft is considered as case study and CFD analysis with the commercial code STAR-CCM+ is performed in order to identify the potential capability to use fuel stored in the tanks as a heat sink for waste heat dissipated by other systems. The complex physical phenomena that characterize the heat transfer inside liquid fuel, at the fuel-ullage interface and inside the ullage are outlined. Boundary conditions, including the effect of different ground and flight conditions, are implemented in the numerical simulation approach. The analysis is implemented for a portion of aluminium wing fuel tank, including the leading edge effects. Effect of liquid fuel transfer among different tank compartments and the air flow in the ullage is included. According to Fuel Tank Flammability Assessment Method (FTFAM) proposed by the Federal Aviation Administration, the results are exploited in terms of exponential time constants and fuel temperature difference to the ambient for the different cases investigated.
Gravitational radiation by cosmic strings in a junction

The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one string leg. The effects of polarization of the excitations and of the back-reaction of the gravitational radiation on the small scale structure of the strings are studied.
A generative-discriminative framework for time-series data classification

This thesis targets the problem of poor performance of HMM-based classifiers. First, we study the effect of the structure on the performance of HMMs and see how the number of states and the topology can contribute to the classification performance. As a result, our investigation showed the topology has a stronger contribution to the classification performance than the number of states. Second, we propose a general two-stage framework that combines generative and discriminative models to reach a high performance in the classification of time-series data. In the first stage, HMMs are used to model the time-series data, then a fixed size score vector is extracted from this stage and used as the input to the discriminative model in the second stage. The framework showed a potential for combining generative and discriminative models for in time-series data classification and was able to achieve a recognition rate of 98.02%, with an increase of 3.83% over traditional HMM-based classifiers. (Abstract shortened by UMI.)
On the mass of ultra-light bosonic dark matter from galactic dynamics

We consider the hypothesis that galactic dark matter is composed of ultra-light scalar particles and use internal properties of dwarf spheroidal galaxies to establish a preferred range for the mass mϕ of these bosonic particles. We re-investigate the problem of the longevity of the cold clump in Ursa Minor and the problem of the rapid orbital decay of the globular clusters in Fornax and dwarf ellipticals. Treating the scalar field halo as a rigid background gravitational potential and using N-body simulations, we have explored how the dissolution timescale of the cold clump in Ursa Minor depends on mϕ. It is demonstrated that for masses in the range 0.3 × 10−22 eV < mϕ < 1 × 10−22 eV, scalar field dark halos without self-interaction would have cores large enough to explain the longevity of the cold clump in Ursa Minor and the wide distribution of globular clusters in Fornax, but small enough to make the mass of the dark halos compatible with dynamical limits. It is encouraging to see that this interval of mϕ is consistent with that needed to suppress the overproduction of substructure in galactic halos and is compatible with the acoustic peaks of cosmic microwave radiation. On the other hand, for self-interacting scalar fields with coupling constant λ, values of mϕ4/λ≲0.55 × 103 eV4 are required to account for the properties of the dark halos of these dwarf spheroidal galaxies.
Investigation of active-region doping on InAs/GaSb long wave infrared detectors

The eight-band k⋅p model is used to establish the energy band structure model of the type-II InAs/GaSb superlattice detectors with a cut-off wavelength of 10.5 μm, and the best composition of M-structure in this type of device is calculated theoretically. In addition, we have also experimented on the devices designed with the best performance to investigate the effect of the active region p-type doping temperature on the quantum efficiency of the device. The results show that the modest active region doping temperature (Be: 760 °C) can improve the quantum efficiency of the device with the best performance, while excessive doping (Be: > 760 °C) is not conducive to improving the photo response. With the best designed structure and an appropriate doping concentration, a maximum quantum efficiency of 45% is achieved with a resistance–area product of 688 Ω ⋅cm2, corresponding to a maximum detectivity of 7.35 × 1011cm ⋅ Hz1/2/W.
Gravitational lensing in general relativity via bifurcation theory

In a Lorentzian manifold, conjugate points along a lightlike are endpoints of homotopies of lightlike geodesics, up to first order infinitesimals. When studying phenomena on a very large scale in general relativity, like the gravitational lensing effect, the first order approximation is not a valid approach. In this paper we discuss a multiplicity result for light rays issuing from a light source and reaching an observer placed at a conjugate point of a lightlike geodesic using Krasnosel'skii–Rabinowitz bifurcation theory.
Requirements for leaf position accuracy for dynamic multileaf collimation

Intensity modulated radiation therapy can be achieved by driving the leaves of a multileaf collimator (MLC) across an x-ray therapy beam. Algorithms to generate the required leaf trajectories assume that the leaf positions are exactly known to the MLC controller. In practice, leaf positions depend upon calibration accuracy and stability and may vary within set tolerances. The purpose of this study was to determine the effects of potential leaf position inaccuracies on intensity modulated beams. Equations are derived which quantify the absolute error in delivered monitor units given a known error in leaf position. The equations have been verified by ionization chamber measurements in dynamically delivered flat fields, comparing deliveries in which known displacements have been applied to the defined leaf positions with deliveries without displacements applied. The equations are then applied to two clinical intensity modulations: an inverse planned prostate field and a breast compensating field. It is shown that leaf position accuracy is more critical for a highly modulated low-dose intensity profile than a moderately modulated high-dose intensity profile. Suggestions are given regarding the implications for quality control of dynamic MLC treatments.
Deconstructable systems for sustainable design of steel and composite structures

According to the U.S. Energy Information Administration, construction and use of buildings consumed almost half of the total energy used in the United States in 2012. Design for Deconstruction (DfD) of buildings was proposed to minimize the environmental impacts and reduce the pollution and waste produced during the construction and demolition of buildings by reclaiming the materials at the end of the service life of buildings. Traditional steel-concrete composite flooring system makes the most efficient use of the two materials, with steel being subjected to tension and concrete resisting compression. However, in this system the concrete slabs are poured integrally with the supporting steel framing systems, inhibiting the separation and reuse of the structural components. The objectives of the proposed research are to develop new structural system concepts for deconstructable steel and steel-concrete composite construction to facilitate DfD coupled with the use of recycled materials in sustainably optimized construction. The proposed system not only maintains the benefits offered by composite construction but also enables disassembly and reuse of the structural components. This dissertation first describes the deconstructable composite floor system utilizing clamping connectors. This floor system is anticipated to be used along with all-bolted construction for the remainder of the structure to facilitate deconstruction. The environmental benefits of utilizing DfD in the design of buildings is demonstrated with the life cycle assessment results of prototype structures. The experimental program for investigating the performance of the system is then introduced. Pushout tests are conducted to quantify the strength and ductility of the clamping connectors and evaluate
Rancangan Implementasi Pembangkit Listrik Tenaga Surya (PLTS) Skala Rumah Tangga menggunakan Software HOMER

Kebutuhan energi listrik menjadi kebutuhan pokok bagi masyarakat khususnya di Pulau Terong Kota Batam. Jumlah pelanggan yang menikmati listrik PLN adalah 514 pelanggan. Energi listrik yang dirasakan oleh masyarakat masih belum optimal, karena pembangkit beroperasi rata-rata 14 jam perhari. Untuk dapat mengoptimalkan energi listrik, maka dilakukan suatu perancangan pembangkit listrik memanfaatkan energi surya. Perancangan ini difokuskan pengguna daya 450 dan 900 VA menggunakan software Hybrid Optimization Model for Electric Renewable (HOMER). Perancangan menjadi dua sistem yaitu on grid dan off grid. HOMER akan melakukan simulasi, optimalisasi, dan sensitivitas pada perancangan. Hasil perancangan Pembangkit Listrik Tenaga Surya (PLTS) menggunakan HOMER untuk kategori 450 VA on grid merekomendasikan sistem yang terdiri dari PV 1 kWp, battery 2 unit, dan inverter 3 kW dengan total biaya NPC sebesar US$1.634, sedangkan untuk sistem off grid terdiri dari 2 kWp, Battery 5 unit, dan Inverter 3 kW dengan total biaya NPC sebesar US$5.378. Kategori 900 VA on grid terdiri dari PV 1,5 kWp, battery 2 unit, dan inverter 3 kW dengan total biaya NPC sebesar US$7.361, sedangkan untuk sistem off grid terdiri dari 2,5 kWp, Battery 15 unit, dan Inverter 3 kW dengan total biaya NPC sebesar US$12.116.
LUMINOSITY AND REDSHIFT DEPENDENCE OF THE COVERING FACTOR OF ACTIVE GALACTIC NUCLEI VIEWED WITH WISE AND SLOAN DIGITAL SKY SURVEY

In this work, we investigate the dependence of the covering factor (CF) of active galactic nuclei (AGNs) on the mid-infrared (MIR) luminosity and the redshift. We constructed 12 and 22 μm luminosity functions (LFs) at 0.006 ⩽z ⩽ 0.3 using Wide-field Infrared Survey Explorer (WISE) data. Combining the WISE catalog with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 223,982 galaxies at 12 μm and 25,721 galaxies at 22 μm for spectroscopic classification. We then identified 16,355 AGNs at 12 μm and 4683 AGNs at 22 μm by their optical emission lines and cataloged classifications in the SDSS. Following that, we estimated the CF as the fraction of Type 2 AGN in all AGNs whose MIR emissions are dominated by the active nucleus (not their host galaxies) based on their MIR colors. We found that the CF decreased with increasing MIR luminosity, regardless of the choice of Type 2 AGN classification criteria, and the CF did not change significantly with redshift for z ⩽ 0.2. Furthermore, we carried out various tests to determine the influence of selection bias and confirmed that similar dependences exist, even when taking these uncertainties into account. The luminosity dependence of the CF can be explained by the receding torus model, but the “modified” receding torus model gives a slightly better fit, as suggested by Simpson.
The Probability Distribution of Binary Pulsar Coalescence Rates. I. Double Neutron Star Systems in the Galactic Field

Estimates of the Galactic coalescence rate (ℛ) of close binaries with two neutron stars (NS-NS) are known to be uncertain by large factors (about 2 orders of magnitude) mainly because of the small number of systems detected as binary radio pulsars. We present an analysis method that allows us to estimate the Galactic NS-NS coalescence rate using the current observed sample and, importantly, to assign a statistical significance to these estimates and calculate the allowed ranges of values at various confidence levels. The method involves the simulation of selection effects inherent in all relevant radio pulsar surveys and a Bayesian statistical analysis for the probability distribution of the rate. The most likely values for the total Galactic coalescence rate (ℛpeak) lie in the range 2-60 Myr-1 depending on different pulsar population models. For our reference model 1, in which the most likely estimates of pulsar population properties are adopted, we obtain ℛtot = 8 Myr-1 at a 68% statistical confidence level. The corresponding ranges of expected detection rates of NS-NS inspiral are 3 × 10-3 yr-1 for the initial LIGO and 18 yr-1 for the advanced LIGO.
Sobolev-orthogonal systems of functions associated with an orthogonal system

For every system of functions which is orthonormal on with weight and every positive integer we construct a new associated system of functions which is orthonormal with respect to a Sobolev-type inner product of the form We study the convergence of Fourier series in the systems . In the important particular cases of such systems generated by the Haar functions and the Chebyshev polynomials , we obtain explicit representations for the that can be used to study their asymptotic properties as and the approximation properties of Fourier sums in the system . Special attention is paid to the study of approximation properties of Fourier series in systems of type generated by Haar functions and Chebyshev polynomials.
Analytical and experimental studies on building mass damper system with semi‐active control device

A concept of improving an optimum building mass damper (OBMD) system through a semi‐active control method for enhancing the efficiency of controlling structural responses is proposed. The proposed concept entails replacing the passive fluid viscous dampers used in an OBMD system with semi‐active magnetorheological dampers, thus transforming the system into a novel semi‐active OBMD (SOBMD) system for better seismic performance. A numerical model based on the Bouc–Wen model with the interpolation technique was established to represent the behavior of the semi‐active magnetorheological dampers. The SOBMD system was then developed on the basis of linear‐quadratic regulator method and a continuous‐optimal control concept. The damping force in the SOBMD system can be manipulated according to the structural response; therefore, the SOBMD system affords the possibility of improving the displacement or acceleration response compared with the original OBMD system. Both of the numerical analysis and the experimental verification demonstrated the superior seismic mitigation ability of the SOBMD system. Several earthquake events with different characteristics were simulated in a series of numerical analysis to further verify the performance of the proposed SOBMD system. In short, the benefits of both the active and passive control system are successfully combined in the proposed SOBMD system.