| Abstract: | Modeling nonlinear systems using Volterra series is a century old method but practical realizations were hampered by inadequate hardware to handle the increased computational complexity stemming from its use. But interest is renewed recently, in designing and implementing filters which can model much of the polynomial nonlinearities inherent in practical systems. The key advantage in resorting to Volterra power series for this purpose is that nonlinear filters so designed can be made to work in parallel with the existing LTI systems, yielding improved performance. This paper describes the inclusion of a quadratic predictor (with nonlinearity order 2) with a linear predictor in an analog source coding system. Analog coding schemes generally ignore the source generation mechanisms but focuses on high fidelity reconstruction at the receiver. The widely used method of differential pnlse code modulation (DPCM) for speech transmission uses a linear predictor to estimate the next possible value of the input speech signal. But this linear system do not account for the inherent nonlinearities in speech signals arising out of multiple reflections in the vocal tract. So a quadratic predictor is designed and implemented in parallel with the linear predictor to yield improved mean square error performance. The augmented speech coder is tested on speech signals transmitted over an additive white gaussian noise (AWGN) channel. |
| Description: | Communications and Signal Processing (ICCSP), 2011 International Conference on |
| URI: | http://dyuthi.cusat.ac.in/purl/4500 |
| Files | Size |
|---|---|
| Quadratic Predi ... ding of Speech Signals.pdf | (884.9Kb) |
| Abstract: | In the present study the effect of hot air recirculation is studied with suitable assumptions. It identifies that, the pressure drop across the tile is a dominant parameter which governs the recirculation. The rack suction pressure of the hardware along with the pressure drop across the tile determines the point of recirculation in the cold aisle. The positioning of hardware in the racks play an important role in controlling the recirculation point. The present study is thus helpful in the design of data centre air flow, based on the theory of jets. The air flow can be modelled both quantitatively and qualitatively based on the results |
| Description: | Division Of Safety And Fire Engineering School Of Engineering Cochin University Of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3666 |
| Files | Size |
|---|---|
| Dyuthi-T1586.pdf | (12.63Mb) |
| Abstract: | This work identifies the importance of plenum pressure on the performance of the data centre. The present methodology followed in the industry considers the pressure drop across the tile as a dependant variable, but it is shown in this work that this is the only one independent variable that is responsible for the entire flow dynamics in the data centre, and any design or assessment procedure must consider the pressure difference across the tile as the primary independent variable. This concept is further explained by the studies on the effect of dampers on the flow characteristics. The dampers have found to introduce an additional pressure drop there by reducing the effective pressure drop across the tile. The effect of damper is to change the flow both in quantitative and qualitative aspects. But the effect of damper on the flow in the quantitative aspect is only considered while using the damper as an aid for capacity control. Results from the present study suggest that the use of dampers must be avoided in data centre and well designed tiles which give required flow rates must be used in the appropriate locations. In the present study the effect of hot air recirculation is studied with suitable assumptions. It identifies that, the pressure drop across the tile is a dominant parameter which governs the recirculation. The rack suction pressure of the hardware along with the pressure drop across the tile determines the point of recirculation in the cold aisle. The positioning of hardware in the racks play an important role in controlling the recirculation point. The present study is thus helpful in the design of data centre air flow, based on the theory of jets. The air flow can be modelled both quantitatively and qualitatively based on the results. |
| Description: | Division of Safety and Fire Engineering, School of Engineering, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3264 |
| Files | Size |
|---|---|
| Dyuthi-T1238.pdf | (12.63Mb) |
| Abstract: | Data centre is a centralized repository,either physical or virtual,for the storage,management and dissemination of data and information organized around a particular body and nerve centre of the present IT revolution.Data centre are expected to serve uniinterruptedly round the year enabling them to perform their functions,it consumes enormous energy in the present scenario.Tremendous growth in the demand from IT Industry made it customary to develop newer technologies for the better operation of data centre.Energy conservation activities in data centre mainly concentrate on the air conditioning system since it is the major mechanical sub-system which consumes considerable share of the total power consumption of the data centre.The data centre energy matrix is best represented by power utilization efficiency(PUE),which is defined as the ratio of the total facility power to the IT equipment power.Its value will be greater than one and a large value of PUE indicates that the sub-systems draw more power from the facility and the performance of the data will be poor from the stand point of energy conservation. PUE values of 1.4 to 1.6 are acievable by proper design and management techniques.Optimizing the air conditioning systems brings enormous opportunity in bringing down the PUE value.The air conditioning system can be optimized by two approaches namely,thermal management and air flow management.thermal management systems are now introduced by some companies but they are highly sophisticated and costly and do not catch much attention in the thumb rules. |
| Description: | Division of Safety and Fire Engineering,School of Engineering,Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2997 |
| Files | Size |
|---|---|
| Dyuthi-T0977.pdf | (12.35Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/4905 |
| Files | Size |
|---|---|
| Dyuthi- T1999.pdf | (4.472Mb) |
| Abstract: | Quantile functions are efficient and equivalent alternatives to distribution functions in modeling and analysis of statistical data (see Gilchrist, 2000; Nair and Sankaran, 2009). Motivated by this, in the present paper, we introduce a quantile based Shannon entropy function. We also introduce residual entropy function in the quantile setup and study its properties. Unlike the residual entropy function due to Ebrahimi (1996), the residual quantile entropy function determines the quantile density function uniquely through a simple relationship. The measure is used to define two nonparametric classes of distributions |
| Description: | Statistics and Probability Letters 82 (2012) 1049–1053 |
| URI: | http://dyuthi.cusat.ac.in/purl/4280 |
| Files | Size |
|---|---|
| Quantile based entropy function.pdf | (207.9Kb) |
| Abstract: | Di Crescenzo and Longobardi (2002) introduced a measure of uncertainty in past lifetime distributions and studied its relationship with residual entropy function. In the present paper, we introduce a quantile version of the entropy function in past lifetime and study its properties. Unlike the measure of uncertainty given in Di Crescenzo and Longobardi (2002) the proposed measure uniquely determines the underlying probability distribution. The measure is used to study two nonparametric classes of distributions. We prove characterizations theorems for some well known quantile lifetime distributions |
| Description: | Statistics and Probability Letters 83 (2013) 366–372 |
| URI: | http://dyuthi.cusat.ac.in/purl/4284 |
| Files | Size |
|---|---|
| Quantile based ... ction in past lifetime.pdf | (227.4Kb) |
| Abstract: | Partial moments are extensively used in literature for modeling and analysis of lifetime data. In this paper, we study properties of partial moments using quantile functions. The quantile based measure determines the underlying distribution uniquely. We then characterize certain lifetime quantile function models. The proposed measure provides alternate definitions for ageing criteria. Finally, we explore the utility of the measure to compare the characteristics of two lifetime distributions |
| Description: | Journal of the Korean Statistical Society 42 (2013) 329–342 |
| URI: | http://dyuthi.cusat.ac.in/purl/4289 |
| Files | Size |
|---|---|
| Quantile based ... cts of partial moments.pdf | (253.9Kb) |
| Abstract: | Partial moments are extensively used in actuarial science for the analysis of risks. Since the first order partial moments provide the expected loss in a stop-loss treaty with infinite cover as a function of priority, it is referred as the stop-loss transform. In the present work, we discuss distributional and geometric properties of the first and second order partial moments defined in terms of quantile function. Relationships of the scaled stop-loss transform curve with the Lorenz, Gini, Bonferroni and Leinkuhler curves are developed |
| Description: | Stat Methods Appl (2013) 22:167–182 DOI 10.1007/s10260-012-0213-4 |
| URI: | http://dyuthi.cusat.ac.in/purl/4290 |
| Files | Size |
|---|---|
| Quantile based ... m and its applications.pdf | (183.4Kb) |
| Abstract: | The thesis is mainly concerned with the study of the bacteriology of freezing of mackerel(Rastrelliger kanaggrta)and prawn (Metgpggaeus ddbsoni) The thesis in four sections describes the salient features of the observations and inferences on the bacteriology of freezing of fishes and prawns. This includes the evaluation of methodology for the optimum recovery of bacteria, bacteriology of the newly caught fish and prawn, the effect of freezing temperatures on the survival of selected species of isolates from fish and prawn and the bacteriology of freezing, frozen storage and thawing of prawn/fish emphasizing the effect contributed by each. |
| Description: | School of marine Science, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3399 |
| Files | Size |
|---|---|
| Dyuthi-T1376.pdf | (5.946Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1212 |
| Files | Size |
|---|---|
| Nirmala Thampuran 1988.PDF | (700.9Kb) |
| Abstract: | Present study consists the quantization of specific metals-- Cr, Cd, Pb, Zn and Cu observed in the experimental bivalve, Villorita species. Bivalve specimens were collected seasonally from the identified three hot spots of Vembanad Lake. Soft tissue concentrations of metals are very sensitive in reflecting changes in the ambient environment and hence important in assessing the environmental quality. Concentrations of Zn in bivalves were fairly high compared to other metals. All the stations showed a maximum concentration during premonsoon and minimum during the other two seasons. Levels of Pb, Cu, Zn, Cd and Cr are between 0-6.17mg/kg, 0-17.224mg/kg, 1.916-255.163mg/kg, 0.325-4.133mg/kg, and 0-15.233mg/kg respectively |
| Description: | Indian Journal of Geo-Marine Sciences Vol. 40 (3), June 2011, pp 424-429 |
| URI: | http://dyuthi.cusat.ac.in/purl/4611 |
| Files | Size |
|---|---|
| Quantization of ... in the Cochin estuary.pdf | (321.3Kb) |
| Abstract: | A dynamical system with a damping that is quadratic in velocity is converted into the Hamiltonian format using a nonlinear transformation. Its quantum mechanical behaviour is then analysed by invoking the Gaussian effective potential technique. The method is worked out explicitly for the Duffing oscillator potential. |
| URI: | http://dyuthi.cusat.ac.in/purl/2559 |
| Files | Size |
|---|---|
| Dyuthi-P0118.pdf | (338.5Kb) |
| Abstract: | A compact, planar, wideband antenna designed by modifying the coplanar waveguide is presented in this letter. The proposed antenna finds a wide range of applications including advanced wireless systems (AWS), DCS-1800, DCS-1900/PCS/PHS, WiBro, BlueTooth/WLAN/WiBree/ZigBee, DMB, Global Star Satellite Phones, and digital cordless phones. Wide bandwidth > 75% centered at 2.50 GHz, quasi-omnidirectional radiation coverage along with moderate gain and efficiency are the salient features of the antenna. A prototype fabricated on a substrate with dielectric constant 4.4 and thickness 1.6 mm occupies an area of (31times 64) mm2. Details of antenna design and discussions on the effect of various antenna parameters on the radiation characteristics are presented. |
| URI: | http://dyuthi.cusat.ac.in/purl/2724 |
| Files | Size |
|---|---|
| Dyuthi-P00361.pdf | (769.8Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1026 |
| Files | Size |
|---|---|
| Jacob K Daniel 1985.pdf | (244.1Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1032 |
| Files | Size |
|---|---|
| Ramachandran Nair V K 1988.pdf | (249.8Kb) |
| Abstract: | The thesis entitled “Queueing Models with Vacations and Working Vacations" consists of seven chapters including the introductory chapter. In chapters 2 to 7 we analyze different queueing models highlighting the role played by vacations and working vacations. The duration of vacation is exponentially distributed in all these models and multiple vacation policy is followed.In chapter 2 we discuss an M/M/2 queueing system with heterogeneous servers, one of which is always available while the other goes on vacation in the absence of customers waiting for service. Conditional stochastic decomposition of queue length is derived. An illustrative example is provided to study the effect of the input parameters on the system performance measures. Chapter 3 considers a similar setup as chapter 2. The model is analyzed in essentially the same way as in chapter 2 and a numerical example is provided to bring out the qualitative nature of the model. The MAP is a tractable class of point process which is in general nonrenewal. In spite of its versatility it is highly tractable as well. Phase type distributions are ideally suited for applying matrix analytic methods. In all the remaining chapters we assume the arrival process to be MAP and service process to be phase type. In chapter 4 we consider a MAP/PH/1 queue with working vacations. At a departure epoch, the server finding the system empty, takes a vacation. A customer arriving during a vacation will be served but at a lower rate.Chapter 5 discusses a MAP/PH/1 retrial queueing system with working vacations.In chapter 6 the setup of the model is similar to that of chapter 5. The signicant dierence in this model is that there is a nite buer for arrivals.Chapter 7 considers an MMAP(2)/PH/1 queueing model with a nite retrial group |
| Description: | Department of Mathematics, Cochin University of Science and Technology. |
| URI: | http://dyuthi.cusat.ac.in/purl/3154 |
| Files | Size |
|---|---|
| Dyuthi-T1128.pdf | (5.806Mb) |
| Abstract: | The objective of the study of \Queueing models with vacations and working vacations" was two fold; to minimize the server idle time and improve the e ciency of the service system. Keeping this in mind we considered queueing models in di erent set up in this thesis. Chapter 1 introduced the concepts and techniques used in the thesis and also provided a summary of the work done. In chapter 2 we considered an M=M=2 queueing model, where one of the two heterogeneous servers takes multiple vacations. We studied the performance of the system with the help of busy period analysis and computation of mean waiting time of a customer in the stationary regime. Conditional stochastic decomposition of queue length was derived. To improve the e ciency of this system we came up with a modi ed model in chapter 3. In this model the vacationing server attends the customers, during vacation at a slower service rate. Chapter 4 analyzed a working vacation queueing model in a more general set up. The introduction of N policy makes this MAP=PH=1 model di erent from all working vacation models available in the literature. A detailed analysis of performance of the model was provided with the help of computation of measures such as mean waiting time of a customer who gets service in normal mode and vacation mode. |
| Description: | Department of Mathematics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3803 |
| Files | Size |
|---|---|
| Dyuthi-T1736.pdf | (5.806Mb) |
| Abstract: | In this thesis we study the effect of rest periods in queueing systems without exhaustive service and inventory systems with rest to the server. Most of the works in the vacation models deal with exhaustive service. Recently some results have appeared for the systems without exhaustive service. |
| Description: | Department Of‘ Mathematics And Statistics,Cochin University Of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3579 |
| Files | Size |
|---|---|
| Dyuthi-T1552.pdf | (3.403Mb) |
| Abstract: | In this thesis we have introduced and studied the notion of self interruption of service by customers. Service interruption in queueing systems have been extensively discussed in literature (see, Krishnamoorthy, Pramod and Chakravarthy [38]) for the most recent survey. So far all work reported deal with cases in which service interruptions are generated by sources other than customers. However, there are situations where interruptions are due to the customers rather than the system. Such situations are especially arise at doctors clinic, banks, reservation counter etc. Our attempt is to quantify a few of such problems. Systematically we have proceed from single server queue (in Chapter 2) to multi-server queues (Chapter 3). In Chapte 4, we have studied a very general multiserver queueing model with service interruption and protection of service phases. We also introduced customer interruption in a retrial setup (in Chapter 5). All models (from Chapter 2 to Chapter 4) that were analyzed involve 'non-preemptive priority' for interrupted customers where as in the model discussed in Chapter 5 interruption of service by customers is not encouraged. So the interrupted customers cannot access the server as long as there are primary customers in the system. In Chapter 5 we have obtained an explicit expression for the stability condition of the system. In all models analyzed in this thesis, we have assumed that no more than one interruption is allowed for a customer while in service. Since the models are not analytically tractable, a large number of numerical illustrations were given in each chapter it illustrate the working of the systems. We can extend the models discussed in this thesis to several directions. For example some of the models can be analyzed with both server induced and customer induced interruptions the results for which are not available till date. Another possible extension of work is to the case where there is no bound on the number of interruptions a customer is permitted to have before service completion. More complex is the case where a customer is permitted to have a nite number (K ≥ 2) of We can extend the models discussed in this thesis to several directions. |
| Description: | Department of Mathematics, Cochin University of Science and Technology. |
| URI: | http://dyuthi.cusat.ac.in/purl/3137 |
| Files | Size |
|---|---|
| Dyuthi-T1111.pdf | (5.338Mb) |
Dyuthi Digital Repository Copyright © 2007-2011 Cochin University of Science and Technology. Items in Dyuthi are protected by copyright, with all rights reserved, unless otherwise indicated.