School of Science and Technology (2015-2019)
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Nazarbayev University School of Science and Technology offers Masters programs in Biology, Computer Science, Physics and Robotics. The programs offer the students the opportunity to conduct their postgraduate studies with world-class faculty at the state-of-the-art campus of Nazarbayev University in Astana.
In the School of Science and Technology, students are afforded the opportunity to develop career building skills such as scientific communications, personal study skills and project planning. You are encouraged and allowed independent thinking while integrating knowledge from a variety of disciplines. You will master creativity, being a self-starter, and be facile in acquiring and interpreting data. You will know the scientific method of data gathering and analysis. As a well-trained and knowledgeable consumer of scientific knowledge and technology, you will better prepare to explore your future career aspirations and serve your community, and your country.
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Item Open Access 1D states of the beryllium atom: Quantum mechanical nonrelativistic calculations employing explicitly correlated Gaussian functions(2011) Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, LudwikVery accurate finite-nuclear-mass variational nonrelativistic calculations are performed for the lowest five 1D states (1s2 2p2, 1s2 2s1 3d1, 1s2 2s1 4d1, 1s2 2s1 5d1, and 1s2 2s1 6d1) of the beryllium atom (9Be). The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. The exponential parameters of the Gaussians are optimized using the variational method with the aid of the analytical energy gradient determined with respect to those parameters. The calculations exemplify the level of accuracy that is now possible with Gaussians in describing bound states of a four-electron system where some of the electrons are excited into higher angular statesItem Open Access A Chaotic Neural Network as Motor Path Generator for Mobile Robotics(IEEE International Conference on Robotics and Biomimetics, 2014) Folgheraiter, Michele; Gini, GiuseppinaThis work aims at developing a motor path generator for applications in mobile robotics based on a chaotic neural network. The computational paradigm inspired by the neural structure of microcircuits located in the human prefrontal cortex is adapted to work in real-time and used to generate the joints trajectories of a lightweight quadruped robot. The recurrent neural network was implemented in Matlab and a software framework was developed to test the performances of the system with the robot dynamic model. Preliminary results demonstrate the capability of the neural controller to learn period signals in a short period of time allowing adaptation during the robot operationItem Open Access A class of infinite convex geometries(2015) Adaricheva, Kira; Nation, J.B.Various characterizations of finite convex geometries are well known. This note provides similar characterizations for possibly infinite convex geometries whose lattice of closed sets is strongly coatomic and lower continuous. Some classes of examples of such convex geometries are givenItem Open Access A combined B-Spline-Neural-Network and ARX Model for Online Identi cation of Nonlinear Dynamic Actuation Systems(Neurocomputing, 2016) Folgheraiter, MicheleThis paper presents a block oriented nonlinear dynamic model suitable for online identi cation.The model has the well known Hammerstein architecture where as a novelty the nonlinear static part is represented by a B-spline neural network (BSNN), and the linear static one is formalized by an auto regressive exogenous model (ARX). The model is suitable as a feed-forward control module in combination with a classical feedback controller to regulate velocity and position of pneumatic and hydraulic actuation systems which present non stationary nonlinear dynamics. The adaptation of both the linear and nonlinear parts is taking place simultaneously on a patterby- patter basis by applying a combination of error-driven learning rules and the recursive least squares method. This allows to decrease the amount of computation needed to identify the model's parameters and therefore makes the technique suitable for real time applications. The model was tested with a silver box benchmark and results show that the parameters are converging to a stable value after 1500 samples, equivalent to 7.5s of running time. The comparison with a pure ARX and BSNN model indicates a substantial improvement in terms of the RMS error, while the comparison with alternative non linear dynamic models like the NNOE and NNARX, having the same number of parameters but greater computational complexity, shows comparable performances.Item Open Access A Double-Layer Metamaterial-Based Technique for Interference Mitigation and Shielding of Planar Microwave Structures(2016-07) Papadimopoulos, Athanasios; Karamanos, Theodosios; Tsitsas, Nikolaos; Valagiannopoulos, Constantinos; Kantartzis, Nikolaos; Tsiboukis, TheodorosAn efficient cloaking-shielding technique based on the use of a double superstrate-layer overlay is developed in this paper for planar microstrips. The metamaterial-inspired formulation reduces considerably the induced on the strip current and the reflected from the microstrip electric field, thus alleviating the electromagnetic susceptibility of microstrip transmission lines. For this purpose, the mathematical analysis and optimization procedure are founded on a semianalytic integral equation algorithm, while a set of numerical results certifies its promising meritsItem Open Access A free/open-source hybrid morphological disambiguation tool for Kazakh(DOI: 10.13140/RG.2.2.12467.43045, 2016-04) Assylbekov, Zhenisbek; Washington, Jonathan; Tyers, Francis; Nurkas, Assulan; Sundetova, Aida; Karibayeva, Aidana; Abduali, Balzhan; Amirova, DinaThis paper presents the results of developing a morphological disambiguation tool for Kazakh. Starting with a previously developed rule-based approach, we tried to cope with the complex morphology of Kazakh by breaking up lexical forms across their derivational boundaries into inflectional groups and modeling their behavior with statistical methods. A hybrid rule-based/statistical approach appears to benefit morphological disambiguation demonstrating a per-token accuracy of 91% in running text.Item Open Access A Lumped-Parameter Model for Nonlinear Waves in Graphene(2015) Wei, Dongming; Hazim, Hamad; Elgindi, Mohamed; Soukiassian, YeranA lumped-parameter nonlinear spring-mass model which takes into account the third-order elastic sti ness constant is considered for mod- eling the free and forced axial vibrations of a graphene sheet with one xed end and one free end with a mass attached. It 's demonstrated through this simple model that, in free vibration, within certain initial energy level and depending upon its length and the nonlinear elas- tic constants, there exist bounded periodic solutions which are non- sinusoidal, and that for each xed energy level, there is a bifurcation point depending upon material constants, beyond which the periodic solutions disappear. The amplitude, frequency, and the corresponding wave solutions for both free and forced harmonic vibrations are cal- culated analytically and numerically. Energy sweep is also performed for resonance applications.Item Open Access A Lumped-Parameter Model for Nonlinear Waves in Graphene(World Journal of Engineering and Technology, 2015) Hazim, Hamad; Wei, Dongming; Elgindi, Mohamed B. M.; Soukiassian, YeranA lumped-parameter nonlinear spring-mass model which takes into account the third-order elastic stiffness constant is considered for modeling the free and forced axial vibrations of a graphene sheet with one fixed end and one free end with a mass attached. It is demonstrated through this simple model that, in free vibration, within certain initial energy level and depending upon its length and the nonlinear elastic constants, that there exist bounded periodic solutions which are non-sinusoidal, and that for each fixed energy level, there is a bifurcation point depending upon material constants, beyond which the periodic solutions disappear. The amplitude, frequency, and the corresponding wave solutions for both free and forced harmonic vibrations are calculated analytically and numerically. Energy sweep is also performed for resonance applicationsItem Open Access A Multi-Modal haptic interface for Virtual Reality and Robotics(Journal of Intelligent and Robotic Systems, 2008-08) Folgheraiter, Michele; Gini, Giuseppina; Vercesi, DarioIn this paper we present an innovative haptic device that combines the electro-tactile stimulation with the force and visual feedbacks in order to improve the perception of a virtual world. We discuss about the sensation evoked in a user by the haptic, force, and visual interface provided by this device, implemented as a special glove, equipped with sensors and actua- tors connected to a PC. The techniques used to recreate tactile and kines- thetic sensations are based on an innovative use of cutaneous stimulation integrated with actuators and 3D modelling techniques. We discuss about the specificity of haptic interfaces, their controllers, their open problems. We present results about generating the sensation of touching virtual ob- jects with our device. Experiments show also that, using a multi-modal sensorial pattern of stimulation, the subject perceives more realistically the virtual object. We discuss about possible use of the same technique as a way to interface intelligent robots.Item Open Access A Neuromorphic Motion Controller for a Biped Robot(Human Performance and Robotics, Satellite Workshop of IEEE Humanoid 2016, 2016) Folgheraiter, Michele; Keldibek, Amina; Aubakir, Bauyrzhan; Salakchinov, Shyngys; Gini, Giuseppina; Mauro Franchi, AlessioHere we propose a neuromorphic control system for a medium size humanoid robot under development in the Robotics and Mechatronics Department at Nazarbayev University and in cooperation with Politecnico di Milano.Item Open Access A New Weibull–Pareto Distribution: Properties and Applications(Communications in Statistics: Simulation and Computation, 2016-11-25) Tahir, M. H.; Cordeiro, Gauss M.; Alzaatreh, Ayman; Mansoor, M.; Zubair, M.Many distributions have been used as lifetime models. In this article, we propose a new three-parameter Weibull–Pareto distribution, which can produce the most important hazard rate shapes, namely, constant, increasing, decreasing, bathtub, and upsidedown bathtub. Various structural properties of the new distribution are derived including explicit expressions for the moments and incomplete moments, Bonferroni and Lorenz curves, mean deviations, mean residual life, mean waiting time, and generating and quantile functions. The Rényi and q entropies are also derived. We obtain the density function of the order statistics and their moments. The model parameters are estimated by maximum likelihood and the observed information matrix is determined. The usefulness of the new model is illustrated by means of two real datasets on Wheaton river flood and bladder cancer. In the two applications, the new model provides better fits than the Kumaraswamy–Pareto, beta-exponentiated Pareto, beta-Pareto, exponentiated Pareto, and Pareto models.Item Open Access A Nonlinear Sliding Mode Controller for IPMSM Drives with an Adaptive Gain Tuning Rule(2015) Jung, Jin-Woo; Dang, Dong Quang; Vu, Nga Thi-Thuy; Justo, Jackson John; Do, Ton Duc; Choi, Han Ho; Kim, Tae HeoungThis paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC methodItem Open Access A note on the definition of deformed exponential and logarithm functions(2009) Oikonomou, Th.; Baris Bagci, G.The recent generalizations of the Boltzmann–Gibbs statistics mathematically rely on the deformed logarithmic and exponential functions defined through some deformation parameters. In the present work, we investigate whether a deformed logarithmic/exponential map is a bijection from R+ /R set of positive real numbers/ all real numbers to R/R+, as their undeformed counterparts. We show that their inverse map exists only in some subsets of the aforementioned co domains. Furthermore, we present conditions which a generalized deformed function has to satisfy, so that the most important properties of the ordinary functions are preserved. The fulfillment of these conditions permits us to determine the validity interval of the deformation parameters. We finally apply our analysis to Tsallis q-deformed functions and discuss the interval of concavity of the Rényi entropyItem Open Access A Penalty Method for Approximations of the Stationary Power-Law Stokes Problem(Electronic journal of differential equations, 2001) Lefton, Lew; Wei, DongmingWe study approximations of the steady state Stokes problem governed by the power-law model for viscous incompressible non-Newtonian flow using the penalty formulation. We establish convergence and find error estimates.Item Metadata only Acceptability and tolerability of liquid versus gel and standard versus virucidal alcohol-based hand rub formulations among dental students(American Journal of Infection Control, 2013-11-01) Stauffer, Fritz; Griess, Marion; Pleininger, Gabriele; Zhumadilova, Anara; Assadian, Ojan; Fritz, StaufferBackgroundHand hygiene is effective to prevent the transmission of microorganisms in health care settings, but compliance remains low, even when easy access to hand cleaning agents is provided. ObjectiveFormulation of alcohol-based hand rub (ABHRs) may influence staff compliance to hand hygiene. The aim of this prospective longitudinal study (1 week) was to investigate possible differences of 4 different gel or liquid ABHR formulations, with or without virucidal claim among dental students. MethodsParticipants were randomly assigned to dental treatment cubicles, equipped with either a gel or a liquid based ABHRs, with our without a virucidal claim. Participants assessed the subjective acceptability and the tolerability of test formulations on their hands over a period of 1 week using the 14 item, 7-point Lickert scale World Health Organization questionnaire. ResultsAll tested ABHRs passed the subjective acceptability criteria of ≥50% above 4 for the items “color and fragrance” and for all other items of >75% above 4 and may be regarded as “good.” Significant differences were observed between the 2 gels but not between the 2 liquid ABHRs. For subjective skin tolerability, no significant difference was observed between the liquid formulations after 1 consecutive week of application. However, the difference between the 2 gels was highly significant. ConclusionVirucidal ABHR formulations may be better accepted and tolerated over prolonged periods by dental students than anticipated. The user acceptability of ABHRs depend more on the specific product's formula than its general category.Item Open Access Accuracy limits on the description of the lowest S excitation in the Li atom using explicitly correlated Gaussian basis functions(2008) Stanke, Monika; Komasa, Jacek; Kedziera, Dariusz; Bubin, Sergiy; Adamowicz, LudwikWe have performed very accurate quantum-mechanical calculations for the two lowest S states of the lithium atom in order to determine the transition energy. In the nonrelativistic part of the calculations performed using the variational method, we explicitly included the nuclear motion. The nonrelativistic wave function was expanded in terms of explicitly correlated Gaussian functions. Next, this wave function was used to calculate the leading 2 relativistic correction is the fine-structure constant and the 3 QED correction. We also estimated the 4 QED correction by calculating its dominating component. The results obtained with Gaussians are compared with the most accurate results obtained recently with the Hylleraas-type basis functionsItem Open Access Accurate non-Born-Oppenheimer calculations of the complete pure vibrational spectrum of D2 with including relativistic corrections(2011) Bubin, Sergiy; Stanke, Monika; Adamowicz, LudwikIn this work we report very accurate variational calculations of the complete pure vibrational spectrum of the D2 molecule performed within the framework where the Born-Oppenheimer (BO) approximation is not assumed. After the elimination of the center-of-mass motion, D2 becomes a threeparticle problem in this framework. As the considered states correspond to the zero total angular momentum, their wave functions are expanded in terms of all-particle, one-center, spherically symmetric explicitly correlated Gaussian functions multiplied by even non-negative powers of the internuclear distance. The nonrelativistic energies of the states obtained in the non-BO calculations are corrected for the relativistic effects of the order of α2 (where α = 1/c is the fine structure constant) calculated as expectation values of the operators representing these effectsItem Open Access Accurate non-Born-Oppenheimer calculations of the complete pure vibrational spectrum of ditritium using all-particle explicitly correlated Gaussian functions(2014) Bubin, Sergiy; Stanke, Monika; Adamowicz, LudwikVery accurate variational calculations of the complete pure vibrational spectrum of the ditritium (T2) molecule are performed within the framework where the Born-Oppenheimer approximation is not assumed. After separating out the center-of-mass motion from the total laboratory-frame Hamiltonian, T2 becomes a three-particle problem. States corresponding to the zero total angular momentum, which are pure vibrational states, are spherically symmetric in this framework. The wave functions of these states are expanded in terms of all-particle, one-center, spherically symmetric explicitly correlated Gaussian functions multiplied by even non-negative powers of the internuclear distance. In the calculations the total energies, the dissociation energies, and expectation values of some operators dependent on interparticle distances are determined.Item Open Access Accurate variational calculations of the ground 2Po(1s22s22p) and excited 2S(1s22s2p2) and 2Po(1s22s23p) states of singly ionized carbon atom(2011) Bubin, Sergiy; Adamowicz, LudwikIn this article we report accurate nonrelativistic variational calculations of the ground and two excited states of C+ ion. We employ extended and well optimized basis sets of all-electron explicitly correlated Gaussians to represent the wave functions of the states. The optimization of the basis functions is performed with a procedure employing the analytic gradient of the energy with respect to the nonlinear parameters of the Gaussians. The calculations explicitly include the effects due to the finite nuclear mass. The calculated transition energies between the three states are compared to the experimentally derived values. Finally, we present expectation values of some small positive and negative powers of the interparticle distances and contact densitiesItem Open Access Achieving Anomalous Refraction with Metasurfaces Composed by Two Ordinary Dielectric Materials(Metamaterials, 2018) Tsitsas, N. L.; Valagiannopoulos, ConstantinosThe optimal parameters of a dielectric metasurface, composed of two alternating rectangular rods, are investigated so that it exhibits significant enhancement in the −1- diffracted order in the transmission region. An efficient integral-equation methodology is used for the numerical computations. Representative results of initial optimizations are presented