Second-order Frame Research Articles

Motion response analysis of large-scale structures with small-scale cylinders under wave action

The influence of small-scale cylinders is always ignored in classical models for hydrodynamic calculations of truss spar platforms and other large-scale structures in published research. This study is focused on this influence on the motion response under the wave action so that the response can be forecast more accurately. A numerical model is proposed to calculate the wave-body interactions under the second-order frame by utilizing the time-domain higher-order boundary element method. The wave loads on small-scale cylinders are calculated by the Morison formula, in which the wave field disturbed by a large-scale structure is taken into account. Three-dimensional elastic rod theory is chosen to analyze the cable force to a platform, and the motion equation for the mooring system and hull are solved simultaneously using the Newmark-β method. A moored truss spar platform is modelled, and the numerical results demonstrate that the existence of small-scale cylinders may lead to a decrease of the motion response of the platform, while the natural frequency will move to a lower frequency. This phenomenon explains why small-scale cylinders, which can be modelled as truss spar play an important role in damping and change the added mass of the platform. Therefore, in order to get more accurate results for motion response, the wave loads of small-scale components cannot be ignored.

CANONICAL FORM IN SECOND-ORDER FRAME BUNDLES IN A NATURAL WAY

Using horizontal n-bases of the tangent bundle of the linear frame bundle [Formula: see text] of an n-dimensional manifold M, the canonical form in the non-holonomic second-order frame bundle of M is introduced as a restriction of the canonical form of the bundle [Formula: see text]. This construction generalizes the ones in the corresponding semi-holonomic and holonomic second-order frame bundles. We prove that the natural projection of the set of all non-holonomic second-order frames of M into [Formula: see text] defines a principal bundle structure.

Statistical Text-to-Speech Synthesis Based on Segment-Wise Representation With a Norm Constraint

In statistical HMM-based text-to-speech systems (STTS), speech feature dynamics is modeled by first- and second-order feature frame differences, which, typically, do not satisfactorily represent frame to frame feature dynamics present in natural speech. The reduced dynamics results in over-smoothing of speech features, often sounding as muffled synthesized speech. In this correspondence, we propose a method to enhance a baseline STTS system by introducing a segment-wise model representation with a norm constraint. The segment-wise representation provides additional degrees of freedom in speech feature determination. We exploit these degrees of freedom for increasing the speech feature vector norm to match a norm constraint. As a result, statistically generated speech features are less over-smoothed, resulting in more natural sounding speech, as judged by listening tests.

Performance response of wireless channels for quantitatively different loss and arrival statistics

In this paper we propose a cross-layer performance evaluation framework for wireless channels and subsequently explore the performance response at the FEC and ARQ enabled data-link layer in terms of frame losses and delays for different first- and second-order error and arrival statistics. For a wireless channel model to be appropriate for various FEC capabilities without the need for extensive measurements of the frame error process for each particular FEC code, the error process of the wireless channel is modeled at the physical layer. We assume weak stationary property for bit error observations and model them using a hidden Markov model. The associated parameters matching algorithm allows us to explicitly capture bit error rate and lag-1 autocorrelation of the bit error process. To explore the performance response of the wireless channel at the data-link layer, a cross-layer extension of the bit error model to the data-link layer is then developed. The performance of applications is evaluated using the queuing-theoretic approach that allows both arrival and error processes to be autocorrelated and still retains analytical tractability. The proposed methodology allows us to obtain estimators of frame loss and delay probabilities in the presence of FEC and ARQ procedures at the data-link layer eliminating the need for time-consuming simulations and extensive measurements of wireless channel characteristics for different error correction capabilities of the data-link layer. It is analytical in nature, efficient for small and moderate frame sizes and suitable for performance control purposes where fixed size frames are used at the data-link layer. Particularly, it provides a way to choose the required correction capability of the FEC code resulting in best possible performance at the data-link layer. Numerical results indicate that first- and second-order bit error and frame arrival statistics significantly affect performance parameters provided by a wireless channel and should be taken into account when choosing an appropriate correction capability of the FEC code for given wireless channel conditions.

A characterization theorem for injective model classes axiomatized by general rules

We continue the work in Zhu et al. [Normal conditions for inference relations and injective models, Theoret. Comput. Sci. 309 (2003) 287–311]. A class Ω of strict partial order structures ( posets, for short) is said to be axiomatizable if the class of all injective preferential models from Ω may be characterized in terms of general rules. This paper aims to obtain some characteristics of axiomatizable classes. To do this, a monadic second-order frame language is presented. The relationship between ℵ 0 -axiomatizability and second-order definability is explored. Then a notion of an admissible set is introduced. Based on this notion, we show that any preferential model, which does not contain any four-node substructure, must be a reduct of some injective model. Furthermore, we furnish a necessary and sufficient condition for the axiomatizability of classes of injective preferential models using general rules. Finally, we show that, in some sense, the class of all posets without any four-node substructure is the largest among axiomatizable classes.

Loss performance model for wireless channels with autocorrelated arrivals and losses

In this paper, we firstly propose simple and computationally efficient wireless channel modeling algorithm that explicitly takes into account first- and second-order statistics of frame error observations. For this purpose we use a discrete-time Markov modulated process with at most single event (error) at any time slot. Then, we identify a class of priority queuing systems of G + G/GI/1/K type capable to model the frame transmission process over wireless channels with correlated arrival and loss processes. Using the proposed frame error process, performance evaluation model of the wireless channel at the data-link layer is then reduced to the special case of ∑ i D-BMAP i /D/1/K queuing system with non-preemptive priority discipline. The proposed queuing representation allows to capture forward error correlation (FEC) and automatic repeat request (ARQ) functionality of the data-link layer as well as distributional and autocorrelational properties of the frame arrival and frame loss processes. This model is further analyzed for a number of performance parameters of interest including probability function of the number of frames in the system and probability function of the number of lost frames. It is shown that the channel response in terms of the mean number of frames in the system and the mean number of lost frames varies substantially for different first- and second-order frame error and arrival statistics. The impact of input statistics is also different for normal ( ρ < 1) and overloaded conditions ( ρ ⩾ 1) of ∑ i D-BMAP i /D/1/K queuing system.

Bundles of acceleration on Banach manifolds

We consider an infinite-dimensional manifold M modelled on a Banach space E and we construct smooth fiber bundle structures on the tangent bundle of order two T 2 M , which consists of all smooth curves of M that agree up to their acceleration, as well as on the corresponding second-order frame bundle L 2 M . These bundles prove to be associated with respect to the identity representation of the general linear group GL ( E ) that serves as the structure group of both of them. Moreover, a bijective correspondence between linear connections on T 2 M and connection forms of L 2 M is revealed.

A generalized second-order frame bundle for Fréchet manifolds

Working within the framework of Fréchet modelled infinite-dimensional manifolds, we propose a generalized notion of second-order frame bundle. We revise in this way the classical notion of bundles of linear frames of order 2, the direct definition and study of which is problematic due to intrinsic difficulties of the space models. However, this new structure keeps all the fundamental characteristics of a frame bundle. It is a principal Fréchet bundle associated (differentially and geometrically) with the corresponding second-order tangent bundle.

Functional translation and second-order frame properties of modal logics

Functional translation and second-order frame properties of modal logics

Second-Order Analysis of Slender Steel Frames under Distributed Axial and Member Loads

In certain types of steel framed structures members can be subjected to significant distributed axial as well as lateral loads along their lengths. The behavior of the member is complicated by the nonlinear interaction between the member force and the member stiffness. The conventional assumption of lumping loads to the member ends can lead to inaccurate results. This paper addresses the second-order analysis of frames with members subjected to gravitational axial loads. The error associated with lumping of distributed loads at the members ends is shown to be nontrivial in certain cases. In most design codes axial loads are assumed to be nodal and do not vary along the member length. Also, the result of previous studies on second-order frame analysis ignores this influence and, therefore, their solutions are only approximate and may be incorrect. The derived element improves the accuracy and widens the scope of application for a computer program based on the concept of “second-order analysis,” the “advanced analysis,” and the proposed “integrated analysis and design approach,” which carries out an analysis simultaneously with design meeting the design code requirements. This proposed approach differs from other available methods for advanced analysis in its simplicity and capability of meeting the current and the widely used design code philosophy based on the first-plastic-hinge concept.

A Practical P-Delta Analysis Method for Type FR and PR Frames

In the stability design of frameworks, attention must be given to the additional moment developed as a result of member and frame amplification effects from compressive axial loads. These secondary moments may have a deleterious effect on the strength and stability of the frame and so they must be reckoned with in the analysis and design processes. These are various approaches ranging from very simple to rather rigorous by which a designer can employ to account for these second-order effects. A simple and effective method of second-order frame analyses was presented in this paper. The method accounts for the P-d and P-D effects by the use of pseudo loads obtained from a first-order analysis of the frame. The method is quite versatile in that it is applicable riot only to rectangular Type FR frames but also to nonrectangular Type PR frames. The validity of the method has been demonstrated and it is therefore recommended for general use.