Perambur S. Neelakanta

Complex permittivity of a conductor-loaded dielectric

The complex permittivity of a composite dielectric containing conducting inclusion is derived. The shape of the inclusions is described by their aspect ratio. The resultant equations describe the frequency dependence of the permittivity exactly, without recourse to empirically derived parameters.

Neural Network Modeling: Statistical Mechanics and Cybernetic Perspectives

Introduction Neural and Brain Complex Concepts of Mathematical Neurobiology Pseudo-Thermodynamics of Neural Activity The Physics of Neural Activity: A Statistical Mechanics Perspective Stochastic Dynamics of the Neural Complex Neural Field Theory: Quasiparticle Dynamics and Wave Mechanics Analogies of Neural Networks Informatic Aspects of Neurocybernetics Appendices: Magnetism and the Ising Spin-Glass Model Matrix Methods in Littles Model Overlap of Replicas and Replica Symmetry Bibliography Index

Microwave absorption by conductor-loaded dielectrics

A theoretical model to predict the microwave absorption by a conductor-loaded dielectric is developed. The microwave power transmission coefficient of the test material is derived in terms of the effective conductivity and permittivity parameters (of the composite material) as a function of volume fraction of the conductor loading. The absorption/transmission characteristics of the test material versus volume fraction of metal loading are described by three distinct regimes having low-loss, lossy and metal-like characteristics. Theoretical predictions are comparable with the measured data pertinent to an iron-plus-dielectric material. >

Development of a neuroinference engine for ADSL modem applications in telecommunications using an ANN with fast computational ability

Abstract Artificial neural networks (ANNs) can be attractive means to achieve smart management efforts in modern telecommunications. Proposed in this paper, is an ANN with fast computational abilities compatible for almost real-time efforts as needed in allocating subschannels to the incoming down-stream of information in the so-called asymmetric digital subscriber line (ADSL) modems. The neuroinference engine facilitated in the proposed ADSL modem is a feedforward, backpropagation-based ANN in which the training and prediction phases are carried out in the entropy (information-theoretic) plane. The ANN is trained by means of an algorithm so as to judiciously allocate the incoming down-stream of data (at the modem) into subchannels of the physical media (on the subscriber access side). The underlying training performed on the ANN enables recognizing the input pattern of the data flow rate (at the ADSL modem) and matching it with the output pattern of access-line subchannel capacity specified by the signal-to-noise characteristics of the physical media. Simulated results are presented and discussed.

Stochastical aspects of neuronal dynamics: Fokker-Planck approach

The Stochastical aspects of noise-perturbed neuronal dynamics are studied via the Fokker-Planck equation by considering the Langevin-type relaxational, nonlinear process associated with neuronal states. On the basis of a canonical, stochastically driven, dichotomous state modeling, the equilibrium conditions in the neuronal assembly are analyzed. The markovian structure of the random occurrence of action potentials due to the disturbances (noise) in the neuronal state is considered, and the corresponding solutions relevant to the colored noise spectrum of the disturbance effects are addressed. Stochastical instability (Lyapunov) considerations in solving discrete optimization problems via neural networks are discussed. The bounded estimate(s) of the Stochastical variates involved are presented, and the noise-induced perturbations on the saturated-state neuronal population are elucidated.

Information-theoretic algorithms in bioinformatics and bio-/medical-imaging: A review

Information-theoretic notion of entropy (in Shannon sense) is a versatile avenue in analyzing bioinformatic details as well as in mining data pertinent to molecular biology. Also, the informatics of bio- and medical-imaging can be comprehended via entropy considerations. Presented in this paper is a comprehensive review on salient methods, newer techniques and open-questions on unexplored efforts vis-à-vis the entropy principles cast on bioinformatic computations and bio-/medical-image informatics. Supplementing energetics algorithms are indicated

A co-evolution model of competitive mobile platforms: technoeconomic perspective

A model depicting competitive technoeconomics of business structures specific to mobile-platforms is developed. The underlying co-evolution of large, competing enterprises of mobile-platforms that face customer-churning due to application-preferences and pricing structures in the deregulated ambient is viewed in the perspectives of nonlinear logistic systems akin to that of biological ecosystems. Relevant considerations are decided by and embodied with several stochastically-interacting subsystems. Hence, the temporal dynamics of competition/co-evolution of known competitors in the mobile-platform market, like Android, Symbian and iPhone is depicted by a novel model posing dichotomy of prey-predator flip-flops in the market; and, an asymptotic projection of ex post computations of underlying technoeconomics into the ex ante region would correspond to futuristic forecasts on the performance of test platforms. Further, computed results are exemplified with a sample calculation and associated sensitivity details.

Microwave reflection at an active surface imbedded with fast-ion conductors

The microwave reflection characteristics at a surface of a composite medium composed of thermally controllable, solid-electrolyte-based active zones are studied. These zones are energized (heated) reconfigurably so as to alter their electric conductivity, and hence their reflection/transmission characteristics. Experimental studies at X-band frequencies on a test active surface formed by a two-dimensional array of AgI pellets (fast-ion conductors) imbedded in a dielectric medium are presented. The suitability of the proposed composite medium for broadband applications is indicated. >

Arbitrated Sharing of Traffic in Telecommunication Networks: Technoeconomical Considerations

The technoeconomical aspects of implementing an arbitrated sharing of telecommunication traffic by CO (class 5) circuit-switches are studied. The traffic in question refers voice calls and dial-up modem data supported on network access lines terminated at the circuit-switches. Such time-division multiplexed (TDM) services still remain as the major revenue-earning products of public switched telephone network service-providers (and this statusquo is expected to continue over several future years, despite of xDSL and/or IP-network penetrations). As such, this study was motivated to address an engineering effort to realize higher revenue-potentials through prudent sharing of the traffic between the circuit-switches. This arbitration in traffic-sharing is based on the diversity in the dynamics of traffic-demand posed by different subscribers (such as suburban-based residential customers and urban-based commercial end-users). The centum call seconds (CCS) metric is adopted to specify the traffic-load commensurate with the voice/dial-up modem sources. The heuristics of fair-proportioning considerations that let the switches serving a diverse population of subscribers so as to optimally vary (share) the traffic-load between switches via an arbitrated approach is discussed. Relevant metric for arbitration is defined in terms of a cross-entropy based complexity measure and an implementation scheme is proposed thereof. Computed results on traffic sharing algorithm are presented and discussed.

Conceiving THz Endometrial Ablation:Feasibility, Requirements and Technical Challenges

Shallow-ablation of endometrial lining using microwaves has been traditionally indicated as a minimally invasive treatment option for dysfunctional uterine bleeding (DUB). Known as microwave endometrial ablation (MEA), relevant procedure is used as an alternative to hysterectomy considering its safety, simplicity and effectiveness. In lieu of the prevailing MEA techniques, it is attempted in this study to foresee the possibility of conceiving an alternative and a newer option on endometrial ablation using mm-wave/THz frequencies. Commensurate with this motivated impetus, objectively considered are merits and design issues of using electromagnetic (EM) spectrum of mm-wave/THz region toward optimal conversion of EM energy into a thermal ablative source so that, the basal layer of endometrium can be effectively destroyed in surgical contexts as necessary. Hence, the feasibility of designing appropriate TEA applicators for controlled and safe procedures so as to ablate just the unwanted tissues within a localized zone of energy field is addressed. Lastly, a quantitative analysis on the interaction of THz EM-energy versus the lossy dielectric characteristics of endometrial medium is indicated to model the underlying (THz-energy)-to-(thermal energy) transduction. Relevant prospects of conceiving TEA and the associated pros and cons are identified specific to the prospects of feasibility, requirement considerations and technical challenges.