Dynamic Analysis of A Deep-Water Compliant Vertical Access Riser with A Variable Length During Installation

Compliant vertical access risers(CVAR)have broad application prospects in deep-water oil and gas transportation.However,the mechanical behaviors of the CVAR with a variable length during installation remains unclear.To address this issue,based on the flexible segment method,a model of CVAR with a variable length during installation is established in this study,which is verified by the comparison with commercial software.Then,the mechanical behaviors of CVAR during installation are investigated.The results reveal that the CVAR configuration is significantly affected by the buoyancy blocks.The streamwise displacement of CVAR increases with the increase of current velocity.When the BOP weight is insuffcient,obvious upbending is observed in the lower region and transition region,leading to local compression.When the platform moves in the opposite direction to the current,the maximum stress is larger than that of the scenario when the platform moves in the same direction as the current.

An efficient non-iterative smoothed particle hydrodynamics fluid simulation method with variable smoothing length

In classical smoothed particle hydrodynamics(SPH)fluid simulation approaches,the smoothing length of Lagrangian particles is typically constant.One major disadvantage is the lack of adaptiveness,which may compromise accuracy in fluid regions such as splashes and surfaces.Attempts to address this problem used variable smoothing lengths.Yet the existing methods are computationally complex and non-efficient,because the smoothing length is typically calculated using iterative optimization.Here,we propose an efficient non-iterative SPH fluid simulation method with variable smoothing length(VSLSPH).VSLSPH correlates the smoothing length to the density change,and adaptively adjusts the smoothing length of particles with high accuracy and low computational cost,enabling large time steps.Our experimental results demonstrate the advantages of the VSLSPH approach in terms of its simulation accuracy and efficiency.

Dynamic Analysis of Towed and Variable Length Cable Systems

Towed cable systems are frequently used in marine measurements where the length of the towed cable varies during launch and recovery. In this paper a novel method for modeling variable length cable systems is introduced based on the finite segment formulation. The variable length of the towed cable is described by changing the length of the segment near the towing point and by increasing or decreasing the number of the discrete segments of the cable. In this way, the elastic effects of the cable can be easily handled since geometry and material properties of each segment are kept constant. Experimental results show that the dynamic behavior of the towed cable is consistent between the model and the physical cable. Results show that the model provides numerical efficiency and simulation accuracy for the variable length towed system.

Relationship Between Beak Morphological Variables and Body Size and Mantle Length of Male and Female Argentine Shortfin Squid(Illex argentinus)

Beak of cephalopod is an important hard tissue. Understanding the morphology of beak can yield critical infor- mation on the role of cephalopods in the ecosystem. The south patagonic stock of the Argentine shortfin squid, Illex argentinus, is not only one of the most important fishing targets, but also one of the most important species in the marine eco-system of the southwest Atlantic. A total of 430 samples ofL argentinus, including 229 females 103-346mm in mantle length （ML） and 201 males 140-298mm in ML, were collected from the area off the Exclusive Economic Zone of Argentinean waters by Chinese squid jigging vessels during February to May 2007. The morphology of their beaks was evaluated. The relationships between beak morphological variables and ML differed significantly among males and females. They could be best described by loga- rithmic functions for females and linear functions for males except for upper wing length （UWL） and lower rostrum length （LRL）, which followed exponential functions in their relationships with ML. The results showed the sexual dimorphism in the relationship between ML and beak morphology for the south patagonic stock ofL argentinus. However, no significant differ- ence was found between males and females in the relationships of beak morphological variables （except for UWL） versus body weight （BW）, suggesting that the relationship between beak morphological variables and BW can be used for estimating the biomass consumed by their predators.

Acoustic finite-difference modeling beyond conventional Courant-Friedrichs-Lewy stability limit:Approach based on variable-length temporal and spatial operators

Conventional finite-difference(FD)methods cannot model acoustic wave propagation beyond Courant-Friedrichs-Lewy(CFL)numbers 0.707 and 0.577 for two-dimensional(2D)and three-dimensional(3D)equal spacing cases,respectively,thereby limiting time step selection.Based on the definition of temporal and spatial FD operators,we propose a variable-length temporal and spatial operator strategy to model wave propagation beyond those CFL numbers while preserving accuracy.First,to simulate wave propagation beyond the conventional CFL stability limit,the lengths of the temporal operators are modified to exceed the lengths of the spatial operators for high-velocity zones.Second,to preserve the modeling accuracy,the velocity-dependent lengths of the temporal and spatial operators are adaptively varied.The maximum CFL numbers for the proposed method can reach 1.25 and 1.0 in high velocity contrast 2D and 3D simulation examples,respectively.We demonstrate the effectiveness of our method by modeling wave propagation in simple and complex media.

Improved MPEG-4 High-Efficiency AAC With Variable-Length Soft-Decision Decoding of the Quantized Spectral Coefficients

MPEG-4 High-Efficiency Advanced Audio Coding (HE-AAC) is designed for low bit rate applications, such as audio streaming in mobile communications. The HE-AAC audio codec offers a better coding efficiency since variable-length codes (VLCs) are adopted. However, HE-AAC has originally been designed for storage and error-free transmission conditions. For the transmission over bit error-prone channels, error propagation is a serious problem for the VLCs. Therefore, a robust HE-AAC decoder is desired, especially for mobile communications. In contrast to traditional hard-decision decoding, utilizing bit-wise channel reliability information, softdecision (SD) decoding has been known to offer better audio quality. In HE-AAC, the global gain parameter is coded with fixedlength codes (FLCs), while the scale factors and quantized spectral coefficients are coded with VLCs. In this work, we apply FL/SD decoding to the global gain parameter, VL/SD decoding to the parameters scale factors and quantized spectral coefficients. Especially, in order to apply VL/SD decoding to the quantized spectral coefficients, a new modified trellis representation in VL/SD decoding is proposed. An improved HE-AAC performance is clearly observed, with the support of both instrumental measurements and a subjective listening test.

Detecting network intrusions by data mining and variable-length sequence pattern matching

Anomaly detection has been an active research topic in the field of network intrusion detection for many years. A novel method is presented for anomaly detection based on system calls into the kernels of Unix or Linux systems. The method uses the data mining technique to model the normal behavior of a privileged program and uses a variable-length pattern matching algorithm to perform the comparison of the current behavior and historic normal behavior, which is more suitable for this problem than the fixed-length pattern matching algorithm proposed by Forrest et al. At the detection stage, the particularity of the audit data is taken into account, and two alternative schemes could be used to distinguish between normalities and intrusions. The method gives attention to both computational efficiency and detection accuracy and is especially applicable for on-line detection. The performance of the method is evaluated using the typical testing data set, and the results show that it is significantly better than the anomaly detection method based on hidden Markov models proposed by Yan et al. and the method based on fixed-length patterns proposed by Forrest and Hofmeyr. The novel method has been applied to practical hosted-based intrusion detection systems and achieved high detection performance.

Inverse problem of elastica of a variable-arc-length beam subjected to a concentrated load

An inverse problem of elastica of a variable-arclength beam subjected to a concentrated load is investigated. The beam is fixed at one end, and can slide freely over a hinge support at the other end. The inverse problem is to determine the value of the load when the deflection of the action point of the load is given. Based on the elasitca equations and the elliptic integrals, a set of nonlinear equations for the inverse problem are derived, and an analytical solution by means of iterations and Quasi-Newton method is presented. From the results, the relationship between the loads and deflections of the loading point is obtained.

On constructing symmetrical reversible variable-length codes independent of the Huffman code

Reversible variable length codes (RVLCs) have received much attention due to their excellent error resilient capabilities. In this paper, a novel construction algorithm for symmetrical RVLC is proposed which is independent of the Huffman code. The proposed algorithm's codeword assignment is only based on symbol occurrence probability. It has many advantages over symmetrical construction algorithms available for easy realization and better code performance. In addition, the proposed algorithm simplifies the codeword selection mechanism dramatically.

AN ALGORITHM OF LOCAL PREDICTION FOR CHAOTIC SEQUENCES WITH VARIABLE FRAME LENGTH

According to the issues that the predict errors of chaotic sequences rapidly accumulated in multi-step forecasting which affects the predict accuracy, we proposed a new predict algorithm based on local modeling with variable frame length and interpolation points. The core idea is that, using interpolation method to increase the available sample data, then modeling the chaos dynamics system with least square algorithm which based on the Bernstein polynomial to realize the forecasting. We use the local modeling method, looking for the optimum frame length and interpolation points in every frame to improve the predict peformance. The experimental results show that the proposed algorithm can improve the predictive ability effectively, decreasing the accumulation of iterative errors in multi-step prediction.

On the Cosmic Evolution of the Quantum Vacuum Using Two Variable G Models and Winterberg’s Thesis

We work within a Winterberg framework where space, i.e., the vacuum, consists of a two component superfluid/super-solid made up of a vast assembly (sea) of positive and negative mass Planck particles, called planckions. These material particles interact indirectly, and have very strong restoring forces keeping them a finite distance apart from each other within their respective species. Because of their mass compensating effect, the vacuum appears massless, charge-less, without pressure, net energy density or entropy. In addition, we consider two varying G models, where G, is Newton’s constant, and G-1, increases with an increase in cosmological time. We argue that there are at least two competing models for the quantum vacuum within such a framework. The first follows a strict extension of Winterberg’s model. This leads to nonsensible results, if G increases, going back in cosmological time, as the length scale inherent in such a model will not scale properly. The second model introduces a different length scale, which does scale properly, but keeps the mass of the Planck particle as, ± the Planck mass. Moreover we establish a connection between ordinary matter, dark matter, and dark energy, where all three mass densities within the Friedman equation must be interpreted as residual vacuum energies, which only surface, once aggregate matter has formed, at relatively low CMB temperatures. The symmetry of the vacuum will be shown to be broken, because of the different scaling laws, beginning with the formation of elementary particles. Much like waves on an ocean where positive and negative planckion mass densities effectively cancel each other out and form a zero vacuum energy density/zero vacuum pressure surface, these positive mass densities are very small perturbations (anomalies) about the mean. This greatly alleviates, i.e., minimizes the cosmological constant problem, a long standing problem associated with the vacuum.

Kinematic Characteristics Analysis and Parametric Solving of Snow Melting Agent Throwing Mechanism with Variable Crank Length

Variable crank length cam⁃linkage mechanism has attracted much attention due to its compact overall structure when realizing complex motion laws.According to the special trajectory requirements,the kinematic characteristics and parameters of the mechanism have been analyzed and solved,which lays foundation for the implementation of the variable crank length snow melting agent throwing mechanism designed in this paper.Based on the trajectory equation of the point,the mathematical model of the throwing mechanism was established,and the theoretical trajectory of the end point of the throwing mechanism was obtained by programming.The parametric modeling and trajectory drawing were carried out by computer aided three⁃dimensional interactive application(CATIA),and the correctness of the mathematical model was verified by comparison.The regional trajectory distribution characteristics of the end points of the throwing mechanism were studied by using the trajectory region location method,and the influence of various parameters on the trajectory was investigated by using the numerical cycle comparison method.The human⁃computer interaction system of snow melting agent throwing mechanism with variable crank length was constructed by using Microsoft Visual Basic(VB)software.Based on the restriction conditions,the optimum combination of structural adjustment parameters and operational parameters suitable for Harbin first⁃class roads was obtained by using orthogonal test table,which provides an effective method to solve the parameters of the variable crank length cam mechanism with smooth impulse trajectory.

A C-Based Variable Length and Vector Pipeline Architecture Design Methodology and Its Application

The size and performance of a System LSI depend heavily on the architecture which is chosen. As a result, the architecture design phase is one of the most important steps in the System LSI development process and is critical to the commercial success of a device. In this paper, we propose a C-based variable length and vector pipeline (VVP) architecture design methodology and apply it to the design of the output probability computation circuit for a speech recognition system. VVP processing accelerated by loop optimization, memory access methods, and application-specific cir- cuit design was implemented to calculate the Hidden Markov Model (HMM) output probability at high speed and its performance is evaluated. It is shown that designers can explore a wide range of design choices and generate complex circuits in a short time by using a C-based pipeline architecture design method.

Integrated Joint Source-Channel Symbol-by-Symbol Decoding of Variable-Length Codes Using 3-D MAP Sequence Estimation

Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this paper is to salvage as many data from the damaged packets as possible for higher audiovisual quality. This paper proposes an integrated joint source-channel decoder （I-JSCD） at a symbol-level using three-dimensional （3-D） trellis representation for first-order Markov sources encoded with VLC source code and convolutional channel code. This method combines source code and channel code state-spaces and bit-lengths to construct a two-dimensional （2-D） state-space, and then develops a 3-D trellis and a maximum a-posterior （MAP） algorithm to estimate the source sequence symbol by symbol. Experiment results demonstrate that our method results in significant improvement in decoding performance, it can salvage at least half of （50%） data in any channel error rate, and can provide additional error resilience to VLC stream like image, audio, video stream over high error rate links.

Comprehensive Study on the Basis of Eye Blink, Suggesting Length of Text Line, Considering Typographical Variables the Way How to Improve Reading from Computer Screen

The advent and extensive use of computer and increasing development of different technologies it is important to increase the awareness of issues related to the electronic text or text presentation on computer screen. The usage of web shows the importance of usability and readability of the web applications or sources provide by the web and web textual contents. Web application fails to encounter the user’s requirements in effective manner specially related to textual information, because the designers are unaware from some of the important factors effecting readability, reading from the screen. In this regard, this study is the continuation of the previous work that has been done for the improvement of readability, to handle the readability issues on the basis of Eye Blink for male participants and female participants. To achieve general recommendations for suitable or optimum length of text line for all type of users on the bases of eye blink. Basically during reading from the computer screen focus losses at two positions, when eye blink in the middle of text line and when text line ends. The study specifies suitable length of text line on the basis of Eye Blink, assuming three typographical variables i.e. font style, font color, font size, and with white background, which improve the overall readability or reading from computer screen. The study also shows two important things the degree of understandability and the degree of attractive appearance of different combination.

Variable-length sequential dynamic features-based malware detection

In order to solve the problem that traditional signature-based malware detection systems are inefficacious in detecting new malware,a practical malware detection system is constructed to find out new malware. Application programming interface( API) call sequence is introduced to capture activities of a program in this system. After that,based on variable-length n-gram,API call order can be extracted from API call sequence as the malicious behavior feature of a software. Compared with traditional methods,which use fixed-length n-gram,the solution can find more new malware. The experimental results show that the presented approach improves the accuracy of malware detection.

Analysis of the mass of behind-armor debris generated by RHA subjected to normal penetration of variable cross-section EFP

Analyzing the mass of behind-armor debris (BAD) generated by Rolled Homogeneous Armor (RHA) subjected to normal penetration of variable cross-section Explosively Formed Projectile (EFP) is the purpose of this paper. So theoretical analysis, numerical simulation and experimental data are combined to analyze the influence of variable cross-section characteristic on the time history of crater radius. Moreover the relationships between time history of crater radius (as well as mass of BAD) and the thickness of RHA (from 30mm to 70 mm) and the impact velocity of EFP (1650 m/s to 1860 m/s) are also investigated. The results indicate that: 1) being compared to the variable cross-section characteristic is ignored, the theoretical time history of crater radius is in better agreement with the simulation results when the variable cross-section characteristic is considered;2) being compared to the other three conditions of plug, the theoretical mass of BAD is in the best agreement with the simulation results when the shape of plug is frustum of a cone and the angle between generatrix and bottom is 45- and the axial length of mushroom is considered.

Variable elliptical vibrating screen: Particles kinematics and industrial application

Traditional vibrating screen usually adopts the linear centralized excitation mode,which causes the difficulty in particles loosening and low screening efficiency.The variable elliptical vibrating screen(VEVS)trajectory is regulated to adapt the material mass along the direction of the screen length,improving the particles distribution as well as the screening efficiency.In this work,a theoretical model was developed for analyzing the screen surface motion law during VEVS-based screening process.An equation was obtained to show the relationship between the horizontal amplitude and the vertical amplitude.The materials kinetic characteristics were studied by using high-speed camera during screening process.Compared with equal-amplitude screen(EAS),the material moving velocity was increased by 13.03%on the first half but decreased by 3.52% on the second half,and the total screening time was reduced by 9.42% by using VEVS.In addition,-6 mm screening test was carried out.At the length of VEVS equaled to 1.2 m,the screening efficiency and the total misplaced material content were 92.50% and 2.90%,respectively.However,the screening efficiency was 89.91% and the total misplaced material content was 3.76% during EAS-based screening process.Furthermore,when external moisture is 5.96%,the screening efficiency of VEVS could reach 86.95%.The 2 TKB50113 type VEVS with double-layered screen surface used in Huoshizui Coal Mine was 5.0 m in width and 11.3 m in length.The areas of single layer and double layer were 56.5 and 113 m~2,respectively.In industrial production,the processing capacity was 2500-3000 t/h and the screening efficiency was larger than 90%.

Cognitive Congestion Control for Data Portals with Variable Link Capacity

Network congestion, one of the challenging tasks in communication networks, leads to queuing delays, packet loss, or the blocking of new connections. In this study, a data portal is considered as an application-based network, and a cognitive method is proposed to deal with congestion in this kind of network. Unlike previous methods for congestion control, the proposed method is an effective approach for congestion control when the link capacity and information inquiries are unknown or variable. Using sufficient training samples and the current value of the network parameters, available bandwidth is adjusted to distribute the bandwidth among the active flows. The proposed cognitive method was tested under such situations as unexpected variations in link capacity and oscillatory behavior of the bandwidth. Based on simulation results, the proposed method is capable of adjusting the available bandwidth by tuning the queue length, and provides a stable queue in the network.

Estimating the effect of early discharge policy on readmission rate. An instrumental variable approach

Early discharge policy, common in the developed countries, refers to the reduction of hospital length of stay as a way of reducing the cost of care. The effect of the policy on quality of care has received a lot of attention in the literature. Some of the earlier papers have ignored the endogeneity of length of stay in the readmission equation, an approach that could lead to inconsistent estimation. This study develops a statistical technique for the consistent estimation of the effect of the early discharge policy. An instrument that can be used extensively across different diagnostic groups is provided, hence solving the difficult problem of finding an instrument for length of stay. The exogeneity test in Gorgger (1990), the test for weak instruments in Staiger and Stock (1997) as well as the Hensen (1982) for over identification confirmed respectively that length of stay is endogenous the instrument is strong and the valid.