Most organisms maintain a nearly 24-hour circadian rhythm which allows them to anticipate daily events in the Earth’s solar day. Circadian clocks can be regulated by external time cues such as light/dark (LD) cycles, allowing nocturnal organisms to synchronize their rhythms around dusk in a process known as entrainment. In the absence of external time cues, these rhythms persist, revealing the period of the organism’s internal clock. In nature, day-night cycles have gradual transitions at dawn and dusk, yet these transitions often are not reflected in laboratory studies. Most utilize instantaneous transitions from light to dark, including previous work on spider circadian behavior. To mimic natural conditions, the next logical step is to evaluate how a gradual, dusk transition affects activity patterns and entrainment in nocturnal spiders. Two spider species were used: Pholcus phalangioides and Metazygia wittfeldae. Three hypotheses were identified: 1) spider circadian behavior is unaffected by the type of dusk transition; 2) spider activity entrains to a proportional decrease in light intensity; and 3) spider activity entrains to a specific dimness threshold. Spiders were placed in activity monitors and exposed to 12:12 LD cycles with high (8934 lux) and low (2918 lux) light intensities. There were two groups within each light intensity: one with instantaneous, dusk transitions and one with linear 4-hour transitions. In all experiments, spiders were switched to constant darkness after 5 days of LD cycles to identify the phasing of the circadian clock. In P. phalangioides, there were no significant differences among onsets of activity for high and low light intensities with ramped transitions, nor high and low intensities with instantaneous transitions. The average onset of activity was 0.2 ± 0.1 hours after absolute darkness. For M. wittfeldae, onsets of activity were significantly earlier in ramped than instantaneous LD cycles. However, there was no observable difference in activity onset associated with absolute light intensity for either transition type. The average onset of activity for ramped transitions was 1.9 ± 0.5 hours before complete darkness, while the average onset for instantaneous transitions was 0.5 ± 0.1 hours after complete darkness. Pholcus phalangioides requires complete darkness before activity begins, supporting the hypotheses that either the activity onset is unaffected by the type of dusk transition or requires a very low threshold of light. However, M. wittfeldae began activity about 2 hours earlier or around when light decreases by 50%, supporting the hypothesis that this species entrains to a proportional decrease in light intensity. These activity patterns match their ecologies, as P. phalangioides typically sits and waits in a permanent web while the orbweaver M. wittfeldae begins building a new web during the dusk transition. Overall, these results suggest that ramping light cycles should be considered when circadian rhythms are evaluated in the lab.

Any periodic signal can be decomposed into a sum of oscillating functions. Traditionally, cosine and sine segments have been used to represent a single period of the periodic signal (Fourier Series). In more general cases, each of these functions can be represented by a set of spectral parameters such as its amplitude, frequency, phase, and the variability of its instantaneous spectral components. The accuracy of these parameters depends on several processing variables such as resolution, noise level, and bias of the algorithm used. This thesis presents some background of existing frequency estimation techniques and proposes a new technique for estimating the instantaneous frequency of signals using short sinusoid-like basis functions. Furthermore, it also shows that the proposed algorithm can be implemented in a popular embedded DSPmicroprocessor for practical use. This algorithm can also be implemented using more complex features on more resourceful processing processors in order to improve estimation accuracy

Orientador: Dalgerti Lelis Milanese / Banca: Júlio Borges de Souza / Banca: Milton Itsuo Samesima / Resumo: Realiza-se neste trabalho um estudo da Teoria da Potência Complexa Instantânea aplicada na máquina de indução trifásica, onde são mostrados os vetores espaciais instantâneos (VEI's), pois estes reduzem os parâmetros para estudo (o sistema trifásico é representado por um equivalente ortogonal). Através dos vetores espaciais instantâneos serão calculadas as grandezas de Buchholz-Goodhue para a determinação do aproveitamento da linha (melhoria do fator de potência) - que são recomendados pela norma IEEE 1459-2000. A máquina estará submetida a variadas condições de assimetria e desequilíbrio possibilitando a apresentação de novos parâmetros, que serão utilizadas para a compensação harmônica. / Abstract: It takes place in this work a study of the Theory of the Instantaneous Complex Power applied will be accomplished in the three-phase induction machine, where the instantaneous space phasors are shown (ISP's), because these reduce the parameters for study (the system three-phase is represented by an equivalent orthogonal). Through the instantaneous space phasors the parameters of Buchholz- Goodhue will be calculated for the determination of the use of the line (improvement of the power factor) - that are recommended by the norm IEEE 1459-2000. The machine will be submitted to varied asymmetry conditions and unbalance making possible the presentation of new parameters, which will be used for the harmonic compensation. / Mestre

Orientador: Dalgerti Lelis Milanese / Banca: Júlio Borges de Souza / Banca: Haroldo Rodrigues de Azevedo / Resumo: Este trabalho tem o objetivo de abordar a Teoria da Potência Complexa Instantânea, a qual utiliza vetores espaciais instantâneos, e mostrar sua utilidade através de duas aplicações para cargas do sistema trifásico: A ponte retificadora trifásica de seis pulsos e o transitório de partida de um motor de indução trifásico. Os resultados obtidos são comparados com as grandezas de Buchholz-Goodhue no cálculo da potência aparente e do fator de potência, grandezas estas definidas na norma IEEEStd 1459/2000, para sistemas trifásicos operando em regime permanente em condições de desequilíbrio e com formas de onda não-senoidais. Mostra-se a sua utilidade para a análise destes dois sistemas e lança-se um pouco mais de entendimento da relação existente entre estas duas abordagens. A ponte retificadora trifásica é analisada em condições equilibradas, facilitando-se, portanto, a comparação com a teoria convencional para regimes equilibrados e não-senoidais. Com relação ao transitório de partida do motor de indução, fica evidenciado que este pode ser tratado como se estivesse operando em regime para cada valor do escorregamento, durante o período do transitório eletromecânico. / Abstract: This work aims to show The Instantaneous Complex Power approach, which uses instantaneous space vectors, showing its usefulness through two applications: The six pulse three-phase bridge rectifier and the starting transient of an induction motor. The results are compared to the Buchholz-Goodhue quantities, as defined in IEEE-Std 1459/2000, which deals with three-phase power systems under non-sinusoidal and unbalanced conditions. In this way it is possible to improve our understanding of the theory and the Buchholz- Goodhue approach. As the three-phase bridge rectifier is analyzed under balanced conditions, it facilitates the comparison of these two approaches with the conventional power theory for this case. Concerning the induction motor, it is shown that it can be treated as operating on steady-state sinusoidal conditions for every value of its slip during the electromechanical period of the starting process. / Mestre

The objective of this work is to introduce a new method called the Survivorship Instantaneous Log-odds Ratios (SILOR); to illustrate the creation of SILOR from empirical bivariate survival functions; to also derive standard errors of estimation; to compare results with those derived from logistic regression. Hip fracture, AGE and BMI from the Third National Health and Nutritional Examination Survey (NHANES III) were used to calculate empirical survival functions for the adverse health outcome (AHO) and non-AHO. A stable copula was used to create a parametric bivariate survival function, that was fitted to the empirical bivariate survival function. The bivariate survival function had SILOR contours which are not constant. The proposed method has better advantages than logistic regression by following two reasons. The comparison deals with (i) the shapes of the survival surfaces, S(X1, X2), and (ii) the isobols of the log-odds ratios. When using logistic regression the survival surface is either a hyper plane or at most a conic section. Our approach preserves the shape of the survival surface in two dimensions, and the isobols are observed in every detail instead of being overly smoothed by a regression with no more than a second degree polynomial. The present method is straightforward, and it captures all but random variability of the data.

International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, Nevada / A digital frequency discriminator (DFD) of the delay-correlator type is described. The device is shown to have an instantaneous frequency measurement capability on very short pulses. The theoretical performance of the DFD in a noisy background is derived and shown to compare favorably with measured results.

There is a need for generalised definitions of electrical powers to provide a simultaneous common base for measurement, compensation, power quality and identification of source of distortion. The major problem area today is definitions of powers in the presence of harmonics and nonlinear loads in the electrical power system. In such a scenario, there is a problem to accurately measure especially reactive (nonactive) power. This is important for accurate energy billing. Another important area is the mitigation equipment used to remove unwanted polluting quantities from the power system. Definitions of powers have an important role to play in providing the correct information for the optimal design and performance of such equipment. Evaluation of the quality of the power system to enable appropriate allocation costs to those causing deterioration in the power quality also cannot be discounted. To enable this cost allocation, there is a need to identify the polluters and the definitions should indicate degradation in power quality as well as identify the source of this degradation. Finally, it would be very useful if the definitions could also be used to perform a general analysis of the power system. This thesis commenced with investigation of the problem with an in-depth study of the existing definitions, and what other researchers have indicated about this problem, from the definitions perspective. The issues identified with current definitions are that some definitions do not possess the attributes that are related to source-load properties, and others are based on mathematical consideration and lack physical meaning. One issue in measurement of nonactive power is its nature of having zero average value. Another contributing factor is that the presence of source impedance is neglected in definitions. The use of RMS quantities to determine powers, especially instantaneous powers, in the presence of multi-frequency voltages and currents also contributes to the problem. Additionally, RMS based definitions are based on heating effect while not all sourceload relationships are totally of a heating nature. The RMS based definitions also do not satisfy the energy conservation principle. Another issue is that though harmonic currents are used, current definitions still utilise the RMS value of the voltage wave thus losing harmonic information. The solution is to decompose, as accurately as possible, the total instantaneous power into active and nonactive components utilising DC, fundamental and harmonics of voltage and current as well as being based on the power system properties. To enable this, the load model must closely represent the reality. This thesis presents the new instantaneous power definitions to achieve this. In addition to the fundamental, five sub-components for each of the active and nonactive parts are defined. The definitions are based on both the voltage and current DC, fundamental and harmonic components thus retaining harmonic information. Thus these definitions are not only mathematically based but also have a direct relationship with the load. The definitions do not make the assumption of zero source impedance. With good knowledge of the time profile of active and nonactive power components, an accurate time-domain measurement of the active and nonactive power is achieved. The components of powers introduced in the proposed definitions can be utilised to gauge power quality, to identify the source of distortion and to achieve optimal compensation. Based on the new instantaneous power definitions, the definitions for average values of the powers are also proposed. The recognition of positive going and negative going parts of the nonactive power waveform in defining the average nonactive power alleviates the problem of the “zero average nature” of nonactive power. It also retains energy information and satisfies the principle of energy conservation. The new definitions are evaluated for linear and non-linear loads in the presence of harmonics using benchmark case studies. Evaluation results demonstrate good performance of the proposed definitions. The practical applications of the definitions are explored with a number of examples from the areas of measurement of power and energy, compensation, detection of source of distortion and power quality. An application example showing the capability of the definitions in general analysis of a system is also presented. Good and useful results are obtained for all these examples. The proposed definitions are implemented on prototype systems with digital signal processors to demonstrate their practical usability. The proposed definitions are shown to be consistent with the traditional definitions under the conventional sinusoidal conditions, and their relationships to the commonly used existing definitions are also revealed.

Nonlinear control is an important subject drawing much attention. When a nonlinear system undergoes route-to-chaos, its response is naturally bounded in the time-domain while in the meantime becoming unstably broadband in the frequency-domain. Control scheme facilitated either in the time- or frequency-domain alone is insufficient in controlling route-to-chaos, where the corresponding response deteriorates in the time and frequency domains simultaneously. It is necessary to facilitate nonlinear control in both the time and frequency domains without obscuring or misinterpreting the true dynamics. The objective of the dissertation is to formulate a novel nonlinear control theory that addresses the fundamental characteristics inherent of all nonlinear systems undergoing route-to-chaos, one that requires no linearization or closed-form solution so that the genuine underlying features of the system being considered are preserved. The theory developed herein is able to identify the dynamic state of the system in real-time and restrain time-varying spectrum from becoming broadband. Applications of the theory are demonstrated using several engineering examples including the control of a non-stationary Duffing oscillator, a 1-DOF time-delayed milling model, a 2-DOF micro-milling system, unsynchronized chaotic circuits, and a friction-excited vibrating disk. Not subject to all the mathematical constraint conditions and assumptions upon which common nonlinear control theories are based and derived, the novel theory has its philosophical basis established in the simultaneous time-frequency control, on-line system identification, and feedforward adaptive control. It adopts multi-rate control, hence enabling control over nonstationary, nonlinear response with increasing bandwidth ? a physical condition oftentimes fails the contemporary control theories. The applicability of the theory to complex multi-input-multi-output (MIMO) systems without resorting to mathematical manipulation and extensive computation is demonstrated through the multi-variable control of a micro-milling system. The research is of a broad impact on the control of a wide range of nonlinear and chaotic systems. The implications of the nonlinear time-frequency control theory in cutting, micro-machining, communication security, and the mitigation of friction-induced vibrations are both significant and immediate.

No description available.

Time-frequency analysis for non-linear and non-stationary signals is extraordinarily challenging. To capture the changes in these types of signals, it is necessary for the analysis methods to be local, adaptive and stable. In recent years, decomposition based analysis methods were developed by different researchers to deal with non-linear and non-stationary signals. These methods share the feature that a signal is decomposed into finite number of components on which the time-frequency analysis can be applied. Differences lie in the strategies to extract these components: by iteration or by optimization. However, considering the requirements of being local, adaptive and stable, neither of these decompositions are perfectly satisfactory. Motivated to find a local, adaptive and stable decomposition of a signal, this thesis presents Adaptive Local Iterative Filtering (ALIF) algorithm. The adaptivity is obtained having the filter lengths being determined by the signal itself. The locality is ensured by the filter we designed based on a PDE model. The stability of this algorithm is shown and the convergence is proved. Moreover, we also propose a local definition for the instantaneous frequency in order to achieve a completely local analysis for non-linear and non-stationary signals. Examples show that this decomposition really helps in both simulated data analysis and real world application.