A compact fifth-order wideband bandpass filter (BPF) using simple coupled lines with sharp rolloff skirts is proposed in this letter. Five transmission poles within the passband and eight deep ...transmission zeros from 0 to <inline-formula> <tex-math notation="LaTeX">2\!f_{0} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">f_{0} </tex-math></inline-formula> denotes the center frequency of the passband) can be realized through input impedance calculations. For demonstration, a wideband BPF prototype centered at 2.05 GHz with high-stopband rejection is designed and fabricated, whose measured 3-dB fractional bandwidth is of 60% (1.44-2.66 GHz). Good agreement between the simulations and measurements validates the design idea.
We suggest and briefly review a new sort of superrenormalizable models of higher derivative quantum gravity. The higher derivative terms in the action can be introduced in such a way that all the ...unphysical massive states have complex poles. According to the literature on Lee–Wick quantization, in this case the theory can be formulated as unitary, since all massive ghosts-like degrees of freedom are unstable.
Earlier it was found that the zeros and poles of IIR digital filters with finite word length are elements of the set of algebraic numbers. Therefore, not every point of the unit circle of the z-plane ...can be a zero and / or a pole of such digital filters. The position of admissible positions for zeros and poles depends on the degree of algebraic numbers and the length of the fractional part of the coefficients of the equivalent canonical structure of the corresponding order. The formation of the corresponding configurations is considered as a z-plane discretization due to the quantization of the filter coefficients. The z-plane discretization for second-order filters has been well studied. The geometric locus of the corresponding algebraic numbers is a system of concentric circles, that is, plane algebraic curves of the second degree. This paper presents the results of studying the geometrical place of the third order IIR filter zeros and poles.
1. Avian electrocution on power lines is a major conservation issue on a global scale. Electrocution risk models have recently been proposed as an effective alternative to prioritising high-risk pole ...retrofitting activities at a large scale. However, existing models ignore the specific features of the power poles (hereafter, poles) supporting the power distribution lines and make the tenuous assumption that pole density and power line length are key factors to assessing the electrocution risk at a large scale. This assumption may be violated in areas with high variations in pole configuration. 2. In this study, we used data on raptors electrocuted on poles to develop a predictive model of raptor electrocution risk throughout an extensive geographical area in north-western Spain, using boosted regression trees. With the best-fitting model, we predicted the hazard of a set of 188,741 poles and validated the model predictions with new data collected from the study area. 3. Our model highlights the relevance of combining both habitat and technical features to identify the most dangerous poles for raptors on a large geographical scale. A 9.86% of the total poles evaluated were characterised as high risk for raptors. The model showed good performance in external validation. The new electrocution events were registered at poles with high-risk values. 4. Synthesis and applications. In this study, we improved the accuracy of the predictive models of raptor electrocution risk for large geographical areas. By incorporating the technical characteristics of the power poles into the models, we achieved a high level of prediction at the power pole level, which is the ultimate correction unit. This will allow electric companies and wildlife managers to specify retrofitting activities of high-risk power poles for raptors in large geographical areas, thus maximising the effect of investment in the correction of dangerous power poles and conservation of the raptor populations.
Nonsense mutations in the
gene have been most frequently identified among familial microcephaly patients. Depletion of the
orthologue (
) causes spindle pole unfocusing during mitosis in multiple ...cell types. However, it remains unknown whether human ASPM has a similar function. Here, by performing CRISPR-based gene knockout (KO) and RNA interference combined with auxin-inducible degron, we show that ASPM functions in spindle pole organisation during mitotic metaphase redundantly with another microcephaly protein, CDK5RAP2 (also called CEP215), in human tissue culture cells. Deletion of the
gene alone did not affect spindle morphology or mitotic progression. However, when the pericentriolar material protein CDK5RAP2 was depleted in
KO cells, spindle poles were unfocused during prometaphase, and anaphase onset was significantly delayed. The phenotypic analysis of CDK5RAP2-depleted cells suggested that the pole-focusing function of CDK5RAP2 is independent of its known function to localise the kinesin-14 motor HSET (also known as KIFC1) or activate the γ-tubulin complex. Finally, a hypomorphic mutation identified in ASPM microcephaly patients similarly caused spindle pole unfocusing in the absence of CDK5RAP2, suggesting a possible link between spindle pole disorganisation and microcephaly.
Wood poles comprise a portion of the power utility's aging infrastructure that make a significant impact on customer's reliability. A large number may fail under the influence of severe wind storms ...and hurricanes, sometimes resulting in millions of dollars in replacement costs per year to the utilities. A holistic approach to risk assessment of wood poles in power distribution networks would therefore consider the simultaneous effects of decay and natural hazards on the failure probability of the poles. Toward this goal, this paper presents a framework for the development of age-dependent fragility curves of utility wood poles that relies on age-dependent probabilistic capacity models of wood poles and wind induced demand models. The framework considers uncertainties in the initial fiber strength of the wood poles, the age-dependent capacity loss model, the geometric features of wood poles of different classes, and the applied wind loads. The results of this study show that the decay process in wood poles may increase the fragility of the poles significantly as the age of the poles increase. The fragility curves provided in this research may constitute a major component of risk assessment approaches of power distribution networks against hurricanes and strong winds.
Power distribution systems are susceptible to damage from natural hazards, especially hurricanes. Hurricane winds can knock down distribution poles thereby causing power outages resulting in millions ...of dollars in lost revenue and restoration costs. Wood has been the dominant material used to support overhead lines in distribution systems in the US. Recently however, utility companies have been searching for cost-effective alternatives to wood due to environmental concerns, durability concerns and high cost of maintenance. Steel has emerged as a viable alternative to wood due to its advantages such as lower maintenance cost, light weight, consistent performance and invulnerability to insect attacks. Both wood and steel poles are prone to deterioration over time due to decay and corrosion, respectively. As utility companies increasingly adopt the use of steel poles, there is need for a comprehensive approach to compare the long-term reliability and cost-effectiveness of wood and steel poles. This study demonstrates a framework for comparing wood and steel poles subjected to hurricanes through fragility analysis that takes into account the strength deterioration over time. The framework also includes life-cycle cost analysis that incorporates fragility and strength deterioration. To demonstrate the framework, three locations in Florida, Virginia and Massachusetts were considered.
In this article, the performance limitations problem are investigated for a class of signal-input, signal-output networked control systems with repeated zeros and poles. The additive white noise is ...adopted in the communication channel. The tracking performance limitations are investigated based on a two-degree of freedom (2DOF) controller. The results demonstrate that the multiplicity of nonminimum phase (NMP) zeros and unstable poles of the plant can affect the tracking performance limitations. The explicit quantitative relationship is characterized for the tracking performance limitations, which is derived based on NMP zeros, unstable poles of the plant with corresponding multiplicity, as well as the statistical characteristics of the reference noise and communication noise. The admissible infimal signal-to-noise ratio (SNR) is also obtained for the tracking system by using a 2DOF controller structure, where the admissible infimal SNR can satisfy the stability conditions while achieving tracking performance limitations. Finally, an illustrative example is presented to validate the effectiveness of our proposed scheme.
A dominant-pole substitution (DPS) technique for low-dropout regulator (LDO) is proposed in this paper. The DPS technique involves signal-current feedforward and amplification such that an ...ultralow-frequency zero is generated to cancel the dominant pole of LDO, while a higher frequency pole substitutes in and becomes the new dominant pole. With DPS, the loop bandwidth of the proposed LDO can be significantly extended, while a standard value and large output capacitor for transient purpose can still be used. The resultant LDO benefits from both the fast response time due to the wide loop bandwidth and the large charge reservoir from the output capacitor to achieve the significant enhancement in the dynamic performances. Implemented with a commercial 0.18-μm CMOS technology, the proposed LDO with DPS is validated to be capable of delivering 100 mA at 1.0-V output from a 1.2-V supply, with current efficiency of 99.86%. Experimental results also show that the error voltage at the output undergoing 100 mA of load transient in 10-ns edge time is about 25 mV. Line transient responses reveal that no more than 20-mV instantaneous changes at the output when the supply voltage swings between 1.2 and 1.8 V in 100 ns. The power-supply rejection ratio at 3 MHz is -47 dB.
This paper proposes a new algorithm, very efficient numerically, used for locating zeros and poles of complex function and its exemplary applications in microwave technique problems. The algorithm ...starts its run from two arbitrary regions on the complex plane, where the searched function yields values with different signs for either or both real and imaginary parts. The algorithm runs along the path created by the chain of equilateral triangles, at whose vertices the function is evaluated. When analyzing the signs of the function, the tracking directions are chosen along the borders of complex regions, where zeros/poles are further expected. Calculations of complex propagation coefficients for a slab dielectric waveguide, complex dispersion coefficients of graphene transmission lines, and a zero/pole analysis of microwave filters are given to show some of the possible applications of the proposed algorithm. A comparison to other methods is also included.
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