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In this paper, the microbeam, which incorporates with the mid-plane stretching effect and distributed electrostatic force, is considered. After the beam model is introduced briefly, the governing equation of motion of the microbeam is solved by the energy balance method (EBM). The first and the second order approximate periodic solutions are obtained and plotted for various values of the parameters...
In this paper, both analytical and finite element formulations of a rotating thin-walled composite beam are derived for the flapwise bending, chordwise bending and torsional displacements. In the analytical part, derivation of both strain and kinetic energy expressions are made and the equations of motion are obtained by applying the Hamilton's principle. The equations of motion are solved by applying...
In this paper, we present the design and analysis of an innovative modular cubesat structure for ITU pSAT II mission. The design hinges on innovative modular structural columns which support rack-like operation for our ITU pSAT II nanosatellite. ITU pSAT II aims to demonstrate on-orbit a standardized bus architecture and an indigenous in-house developed ADCS. The envisioned structure provides the...
In this study, extension and flapwise bending vibration analysis of a rotating piezolaminated composite Timoshenko beam is performed both analytically and via finite element method. In the analytical part, energy expressions are derived by including the parameters for the hub radius, rotational speed, rotary inertia, shear deformation, slenderness ratio and ply orientation. The Differential Transform...
We propose two encoding strategies for a two user cooperative Orthogonal Frequency Division Multiple Access (OFDMA) system, based on block Markov superposition encoding. We obtain the expressions for the resulting achievable rate regions for both encoding strategies, and evaluate them through simulations. We show that, by allowing for re-partitioning and re-encoding of the cooperative messages across...
Currently network security of institutions highly depend on firewalls, which are used to separate untrusted network from trusted one by enforcing security policies. Security policies used in firewalls are ordered set of rules where each rule is represented as a predicate and an action. This paper proposes modeling of firewall rules via directed acyclic graphs (DAG), from which test cases can be automatically...
Boundary overflows are caused by violation of constraints, mostly limiting the range of internal values of program, and can be provoked by an intruder to gain control of or access to stored data. In order to countermeasure this well-known vulnerability issue, this paper focuses on input validation of graphical user interfaces (GUI). The approach proposed generates test cases for numerical inputs based...
For a cooperative Gaussian multiple access channel (MAC), we propose a new channel adaptive three user cooperation strategy, based on a non-trivial extension of block Markov superposition encoding. We obtain the expressions for the resulting achievable rate region. We demonstrate through simulations that the participation of an extra user in cooperation provides significant rate improvements. The...
For a three user Gaussian multiple access channel (MAC), we propose a new superposition block Markov encoding based cooperation scheme. Our scheme allows the three users to simultaneously cooperate both in pairs, and collectively, by dividing the transmitted messages into sub-messages intended for each cooperating partner. The proposed encoding and decoding at the transmitters take into account the...
For a two user fading Gaussian multiple access channel with user cooperation, we show that window decoding achieves the same sum rate as backwards decoding, when the encoding is done using block Markov superposition coding. We prove this result by showing that when optimum power control is employed, the additional constraints on the sum rate imposed by the use of window decoding instead of backwards...
In this paper a symbol synchronous CDMA system with processing gain where all the users transmit to a single receiver is considered. The receiver and the transmitter have perfect knowledge of the channel states. The set of long term achievable rates, i.e., the capacity region, for a power controlled scalar multiaccess channel is characterized for fading CDMA. The capacity region of a fading CDMA channel...
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