Next generation communication systems are reaching 110Gbps rates. At these frequencies, the skin effect and dielectric loss of copper cables cause inter-symbol interference (ISI) and frequency dependent loss, severely limiting the channel bandwidth. In this thesis, different methods for alleviating ISI are explored. The design of the critical blocks of an adaptive channel equalizer with up to two times oversampling are presented. The circuits were fabricated in a 0.13μm SiGe BiCMOS technology. The linear, adaptive equalizer operates up to 70Gbps and its measured S-parameters exhibit a single-ended peak gain of 12.2dB at 52GHz, allowing for 31dB of peaking between DC and 52GHz. Equalization is demonstrated experimentally at 59Gbps for a cable loss of 17.9dB. These results make it the fastest receive equalizer published to date. A retiming flip-flop operating between 72 and 118 GHz, the highest reported in silicon, is also designed and characterized, showing less than 500-fs jitter.

Next generation communication systems are reaching 110Gbps rates. At these frequencies, the skin effect and dielectric loss of copper cables cause inter-symbol interference (ISI) and frequency dependent loss, severely limiting the channel bandwidth. In this thesis, different methods for alleviating ISI are explored. The design of the critical blocks of an adaptive channel equalizer with up to two times oversampling are presented. The circuits were fabricated in a 0.13μm SiGe BiCMOS technology. The linear, adaptive equalizer operates up to 70Gbps and its measured S-parameters exhibit a single-ended peak gain of 12.2dB at 52GHz, allowing for 31dB of peaking between DC and 52GHz. Equalization is demonstrated experimentally at 59Gbps for a cable loss of 17.9dB. These results make it the fastest receive equalizer published to date. A retiming flip-flop operating between 72 and 118 GHz, the highest reported in silicon, is also designed and characterized, showing less than 500-fs jitter.

<p>With the development of modern data collection approaches, researchers may collect hundreds to millions of variables, yet may not need to utilize all explanatory variables available in predictive models. Hence, choosing models that consist of a subset of variables often becomes a crucial step. In linear regression, variable selection not only reduces model complexity, but also prevents over-fitting. From a Bayesian perspective, prior specification of model parameters plays an important role in model selection as well as parameter estimation, and often prevents over-fitting through shrinkage and model averaging.</p><p>We develop two novel hierarchical priors for selection and model averaging, for Generalized Linear Models (GLMs) and normal linear regression, respectively. They can be considered as "spike-and-slab" prior distributions or more appropriately "spike- and-bell" distributions. Under these priors we achieve dimension reduction, since their point masses at zero allow predictors to be excluded with positive posterior probability. In addition, these hierarchical priors have heavy tails to provide robust- ness when MLE's are far from zero.</p><p>Zellner's g-prior is widely used in linear models. It preserves correlation structure among predictors in its prior covariance, and yields closed-form marginal likelihoods which leads to huge computational savings by avoiding sampling in the parameter space. Mixtures of g-priors avoid fixing g in advance, and can resolve consistency problems that arise with fixed g. For GLMs, we show that the mixture of g-priors using a Compound Confluent Hypergeometric distribution unifies existing choices in the literature and maintains their good properties such as tractable (approximate) marginal likelihoods and asymptotic consistency for model selection and parameter estimation under specific values of the hyper parameters.</p><p>While the g-prior is invariant under rotation within a model, a potential problem with the g-prior is that it inherits the instability of ordinary least squares (OLS) estimates when predictors are highly correlated. We build a hierarchical prior based on scale mixtures of independent normals, which incorporates invariance under rotations within models like ridge regression and the g-prior, but has heavy tails like the Zeller-Siow Cauchy prior. We find this method out-performs the gold standard mixture of g-priors and other methods in the case of highly correlated predictors in Gaussian linear models. We incorporate a non-parametric structure, the Dirichlet Process (DP) as a hyper prior, to allow more flexibility and adaptivity to the data.</p> / Dissertation

The Master's degree paper provides the analysis of pay system in State owned company Telšiai Region Roads; theoretical and practical aspects of its creation and implementation. The survey data allowed us to identify and evaluate employees’ expectations and state the drawbacks. To improve employees’ interest towards work an empirical research was carried out during which the main functions of work organization in a company were evaluated, related problems were identified as well as their causes and possible solutions to them. The research results confirmed the author's hypothesis that there are some considerable problems regarding creation and implementation of pay system in an organization, which hinders the state enterprise from successful further development.

Darbe analizuojami ES-Baltarusijos ir ES-Kaliningrado santykiai, vadovaujantis Fabrizio Tassinari suformuluota „kintamųjų geometrijų“ koncepcija. „Kintamųjų geometrijų“ sąvoka, asocijuojama su ES vidaus politika, pritaikoma ES santykių su kaimyninėmis valstybėmis analizei. Naujas kontekstas bei dalinis teorinės koncepcijos modifikavimas leidžia tirti ES gravitacinės bei normatyvinės galios poveikį bei vertinti jos kaip užsienio politikos veikėjos sėkmes bei nesėkmes. Tyrimui pasirinkti du atvejai - Lietuvos kaimynystėje esančių Baltarusijos valstybės bei Rusijos Federacijos Kaliningrado srities santykiai su ES. Taikant teorinės analizės bei aprašomąjį metodą siekiama ne tik išnagrinėti ES-Baltarusijos ir ES-Kaliningrado santykius, bet ir įvertinti, kokia reikšmė jiems suteikiama platesniame Europos kontekste. „Kintamųjų geometrijų“ koncepcija skaldoma į tris sudedamąsias dalis – „idėjų“, „institucijų“ bei „ galios“ dimensijas. Ši segmentacija nulemia uždavinių formuluotę, darbo struktūrą bei esmines išvadas. „Idėjų“ matmuo skirtas ES, Baltarusijos ir Kaliningrado politinio ir geopolitinio identitetų bei jų sąveikos tyrimui, „institucijų“ dimensija pasitelkiama, kritiškai nagrinėjant skirtingus bendradarbiavimo formatus bei jų trūkumus. Pats svarbiausias - „galios“ matmuo leidžia nubrėžti teorinės koncepcijos praktinio taikymo ribas, analizuojant ES galios vaidmenį ir nurodant alternatyvius galios šaltinius. Tyrimo rezultatai leidžia nustatyti pasirinktos teorijos taikymo... [toliau žr. visą tekstą] / The paper deals with the analysis of the EU-Belarus and the EU-Kaliningrad relations applying the concept of “variable geometries“ introduced by Fabrizio Tassinari. In the conventional interpretation this concept is associated with the domestic policy of the EU. This study places it in the field of the Union‘s relations with its neighbours. New context and partial modification of the theory make it possible to examine the impact of the EU gravitational and normative power and evaluate successes and failures of the Union‘s external policy. Two topical cases have been chosen for the investigation – Lithuania‘s neighbouring Belarus and the Russian Federation Kaliningrad region relations with the EU. Selected methodology – the combination of theoretical analysis and descriptive methods – gives the possiblity to simultaneously examine the EU-Belarus and the EU-Kaliningrad relations and evaluate their role in the wider European space. Three dimensions of „variable geometries“ are distinguished: „ideas“, „institutions“ and „power“. This segmentation determines the formulation of the study tasks, structure and the main conclusions. The dimension related to „ideas“ focuses on the EU, Belarus and Kaliningrad political and geopolitical identities and on the way in which the EU as a polity affects, and is affected by, deeper relations with its neighbors. The institutional dimension deals with different formats of cooperation and their shortcomings. The main dimension, related to “power”... [to full text]

Įprasti elektromechaninių vykdymo sistemų dinamikos optimizavimo metodai – kiekybinis ir simetrinis optimumai turi savų privalumų bei trūkumų ir yra pagrįsti pastovios struktūros greičio reguliatoriais: proporciniu (P) ir proporciniu integruojančiu (PI). Siekiant suderinti kiekybinio ir simetrinio optimumų tiekiamus privalumus bei pašalinti jų trūkumus, užtikrindamas elektromechaninės vykdymo sistemos greičio dinaminį nuokrypį neviršijantį 5 % ir nulinį greičio statinį nuokrypį ištirtas P-PI valdymo dėsnio kintamos struktūros reguliatorius. Remiantis ITAE integraliniu kokybės rodikliu nustatyta geriausią elektromechaninės vykdymo sistemos dinamikos kokybę užtikrinanti greičio reguliatoriaus valdymo dėsnio perjungimo parametro priklausomybė nuo statinės apkrovos. Atlikti elektros pavaros su kintamos struktūros greičio reguliatoriumi veikimo imitacijos tyrimai MATLAB/Simulink programa. Nustatyta, kad P-PI kintamos struktūros reguliatorius užtikrina nuo 60,7 % iki 83,15 % geresnę elektromechaninės vykdymo sistemos dinamikos kokybę nei pastovios struktūros simetrinio optimumo reguliatorius (PI). Tačiau naudojant P-PI kintamos struktūros reguliatorių gaunama nuo 2,76 % iki 13,67 % blogesnė sistemos dinamikos kokybė nei PI-P-PI kintamos struktūros reguliatoriaus atveju. / Classical dynamics optimization methods of the electromechanical servo drives are the quantitative and symmetrical optimums. These methods have advantages and disadvantages and are based on the fixed structure velocity controllers – proportional (P) and proportional-integrating (PI). In order to coordinate the advantages and eliminate disadvantages of the quantitative and symmetrical optimum methods have been investigated the P-PI variable structure velocity controller in the electromechanical servo drive. The P-PI variable structure velocity controller ensures that the dynamic error does not exceed 5 % and enables avoiding the static velocity error. According to the ITAE (Integral of Time multiplied by Absolute Error) quality indicator it was determined the control law switching parameter dependence on the static load ensuring the best dynamical quality of the electromechanical servo system. The investigations have been accomplished simulating the electromechanical servo system with P-PI variable structure velocity controller using MATLAB/Simulink program. It has been determined that P-PI variable structure velocity controller ensures from 60,7 % to 83,15 % better dynamical quality of the electromechanical servo system compared to the fixed structure controller (PI) of the symmetrical optimum. But using P-PI variable structure velocity controller the dynamical quality declines from 2,76 % to 13,67 % compared to the PI-P-PI variable structure velocity controller.

A general methodology is described in which policyholder behaviour is decoupled from the pricing of a variable annuity based on the cost of hedging it, yielding two sequences of weakly coupled systems of partial differential equations (PDEs): the pricing and utility systems. The utility systems are used to generate policyholder withdrawal behaviour, which is in turn fed into the pricing systems as a means to determine the cost of hedging the contract. This approach allows us to incorporate the effects of utility-based pricing and factors such as taxation. As a case study, we consider the Guaranteed Lifelong Withdrawal and Death Benefits (GLWDB) contract. The pricing and utility systems for the GLWDB are derived under the assumption that the underlying asset follows a Markov regime-switching process. An implicit PDE method is used to solve both systems in tandem. We show that for a large class of utility functions, the two systems preserve homogeneity, allowing us to decrease the dimensionality of solutions. We also show that the associated control for the GLWDB is bang-bang, under which the work required to compute the optimal strategy is significantly reduced. We extend this result to provide the reader with sufficient conditions for a bang-bang control for a general variable annuity with a countable number of events (e.g. discontinuous withdrawals). Homogeneity and bang-bangness yield significant reductions in complexity and allow us to rapidly generate numerical solutions. Results are presented which demonstrate the sensitivity of the hedging expense to various parameters. The costly nature of the death benefit is documented. It is also shown that for a typical contract, the fee required to fund the cost of hedging calculated under the assumption that the policyholder withdraws at the contract rate is an appropriate approximation to the fee calculated assuming optimal consumption.

Two wild blueberry fields were selected in central Nova Scotia, to characterize and quantify the spatial pattern of variability in soil properties, leaf nutrients and fruit yield, identification of yield influencing soil properties, and to develop management zones for site-specific fertilization. A combination of classical statistics, geostatistical analysis and mapping in Arc GIS 9.3 indicated substantial variation within field. The stepwise regression suggested that the soil EC, horizontal co-planar geometry (HCP), inorganic nitrogen and moisture content were major yield influencing factors. The cluster analysis of the soil variables with the fruit yield also indicated that HCP, inorganic nitrogen, EC, SOM, and ?v were closely grouped with the fruit yield at a similarity level greater than 70%. Based on the results of this study the wild blueberry fields can be divided into different management zones for variable rate fertilization to improve crop production, increase revenue, and reduce potential environmental contamination.

Two of the most significant challenges facing the world in the 21st century are improving energy security and mitigating the effects of climate change. To counter these challenges, renewable energy sources, such as wind, are considered a possible solution and have gained importance worldwide. With many jurisdictions setting high wind-energy targets for the coming decades, risks have grown as the demand for new wind turbines has outstripped the growth of its suppliers. Integrating significant amounts of wind-electricity into existing networks raises reliability concerns due to variable nature of wind. A method for estimating the reliability of wind-energy systems is presented which is a combination of a forecasting method (probabilistic approach) and RL (Resistance-Load) technique (risk-based approach), demonstrated through a case study, and verified using real-time wind farm data.

Two wild blueberry fields were selected to evaluate the impact of variable rate (VR) fertilization on crop productivity, surface and subsurface water quality. Management zones were delineated based on slope variability, and different fertilizer rates were applied according to prescription maps. Runoff collectors were place in the fields to measure the nutrient losses in surface runoff, while lysimeters were installed to evaluate the impact of VR fertilization (VRF) on subsurface water quality. The VR treatment significantly decreased phosphorus and nitrogen loadings in surface runoff as compared to uniform treatment. The concentrations of nutrients in subsurface water samples were also significantly lower for VR treatment as compared to uniform treatment. The excessive nutrients enhanced vegetative growth in low lying areas of uniform fertilization, while berry yield was less. Based on these results, it can be concluded that VRF in wild blueberry fields improved the crop productivity and potential environmental impacts. / This study was conducted to evaluate the impact of variable rate fertilization on crop productivity and surface and subsurface water quality in wild blueberry fields. Result illustrated that variable rate fertilization significantly reduce the nutrients loading in surface and subsurface water, and improved blueberry yield.