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This paper considers a three-axle railway locomotive bogie running on a straight track and presents pattern diversity and bifurcation characteristics of its hunting behaviors at forward speeds higher than the hunting critical speed. Poincare sections describing the cycle characteristic and wheel-rail impacts of the bogie system are defined according to the geometric structure of phase space of the dynamical system for carrying out multi-target and multi-parameter co-simulation analysis. The influences of dynamical parameters of the locomotive bogie on the wheel–rail impacts are studied and some important features of hunting behaviors in the presence of the flange contact nonlinearity are found. A series of grazing bifurcations induce the pattern diversity of hunting behaviors. The impacts of the middle and trailing wheelsets on the rail fall behind that of the leading wheelset, and the impact lag of the hunting motion of the middle wheelset is the most obvious of the three wheelsets. The top branch of impact velocity bifurcation diagram of period 1 hunting motion of the trailing wheelset is slightly lower than those of the leading and middle wheelsets. The instability speed of period 1 hunting-impact motion of the bogie system with worn wheelsets is lower than that with new wheelsets and the impact velocities of the worn wheelsets on the rail become smaller. A method of reasonable matching of primary suspension parameters, which brings about the substantial increase of the instability speed of periodic hunting behavior in the presence of the flange forces, is presented and the matching effect is verified by bifurcation diagrams of impact velocities of the new and worn leading wheelsets versus the forward speed.

The Weinan-Jingyang fault is one of the southern boundary faults of the Gushi secondary depression of the Weihe Basin, China. Geophysical exploration work and field geological surveys have demonstrated that this fault system has a length of approximately 105 km, and extends at least 5 km into the subsurface, with a northerly dip that shallows with depth. Under the influence of long-term displacement on the fault zone, the strata on the north side of the fault within the fault zone dip to the south, and the subsidence centre of the Gushi depression has migrated continuously southward. The Cenozoic activity of the Weinan-Jingyang fault has resulted in a significant dislocation between Paleozoic and Cenozoic strata on either side of the fault. This fault has been active during the Quaternary, especially the late Quaternary, in some places offsetting strata formed during the Ming Dynasty(1368–1644 CE), suggesting that this fault can reliably be regarded being active during Holocene time. Comprehensive re-examination of historical earthquake records, combined with field studies, confirm that the Weinan-Jingyang fault is likely the fault that slipped during a magnitude ~7 earthquake in northeast Xi'an, China in 1568 CE. That earthquake is here re-named the Shaanxi Gaoling Earthquake.

A two-degree-of-freedom periodically-forced system with a clearance is considered. The correlation between dynamic performance and system parameters is studied to find their feasible matching law. The fundamental group of impact motions is defined, which have the excitation period and differ by the number p of impacts. The generation mechanism of complete and incomplete chattering-impact vibration of the system is studied. A series of singular points between any two adjacent fundamental impact motions are found, at which real-grazing and bare-grazing bifurcation boundaries of one of them, saddle-node and period-doubling bifurcation boundaries of the other alternately intersect and create two types of transition regions: hysteresis and tongue-shaped regions. Subharmonic impact motions are found to regularly appear in the tongue-shaped regions. Based on the sampling ranges of parameters, dynamics of the system is studied with emphasis on the influence of system parameters on impact velocities, existence regions and correlative distribution of single-impact periodic motions by multi-parameter and multi-performance co-simulation analysis.

A two-degree-of-freedom system with a clearance and subjected to harmonic excitation is considered. The correlative relationship and matching law between dynamic performance and system parameters are studied by multi-parameter and multi-performance co-simulation analysis. Two key parameters of the system, the exciting frequency ω and clearance δ, are emphasized to reveal the influence of the main factors on dynamic performance of the system. Diversity and evolution of periodic impact motions are analyzed. The fundamental group of impact motions is defined, which have the period of exciting force and differ by the numbers p and q of impacts occurring at the left and right constraints of the clearance. The occurrence mechanism of chattering-impact vibration of the system is studied. As the clearance δ is small or small enough, the transition from 1–p–p to 1–(p+1)–(p+1) motion (the fundamental group of motions, p≥1) basically goes through the processes as follows: pitchfork bifurcation of symmetric 1–p–p motion, period-doubling bifurcation of asymmetric 1–p–p motion, non-periodic or chaotic motions caused by a succession of period-doubling bifurcations, symmetric 1–(p+1)–(p+1) motion generated by a degeneration of chaos. As for slightly large clearance, a series of grazing bifurcations of periodic symmetrical impact motions occur with decreasing the exciting frequency so that the number p of impacts of the fundamental group of motions increases two by two. As p becomes big enough, the incomplete chattering-impact motion will appear which exhibits a chattering sequence in an excitation period followed by a finite sequence of impacts with successively reduced velocity and reaches the non-sticking region. Finally, the complete chattering-impact motion with sticking will occur with decreasing the exciting frequency ω up to the sliding bifurcation boundary. A series of singular points on the boundaries between existence regions of any adjacent symmetrical impact motions with fundamental period are found, i.e., two different saddle-node bifurcation boundaries of one of them, real-grazing and bare-grazing bifurcation boundaries of the other alternately and mutually cross themselves at the points of intersection and create inevitably two types of transition regions: narrow hysteresis and small tongue-shaped regions. A series of zones of regular periodic and subharmonic impact motions are found to exist in the tongue-shaped regions. Based on the sampling ranges of parameters, the influence of dynamic parameters on impact velocities, existence regions and correlative distribution of different types of periodic-impact motions of the system is emphatically analyzed.

In view of this, this paper puts forwards a component retrieval strategy based on design document. First of all, use computer aided software engineering to generate system design document; secondly, convert the design document to XML document with automation tools; thirdly, according to the semantic model of document description specification, use component semantic partition strategy to divide the conceptual component; then put forward the extraction strategy based on multi-Agent system to get the target system architecture, form the topology structure of target system; lastly, use the XML element verification method to verify the correctness of the extraction results. Results show that, component extracted through the extraction strategy contains the semantics and the call relationship between each other, it also has a high accuracy rate and flexible extraction process, it provides a good foundation for component retrieval and assemblage.

With the booming development of border tourism in China, competitions among different tourism destinations in border areas are becoming increasingly fierce. Model construction is the basic work for tourism competitiveness research in border counties. The study analyzes the characteristics of border county tourism competitiveness, summarizes affecting factors and formation mechanism, then constructs a conceptual model consisted with exterior and interior competitiveness. Exterior competitiveness is the ultimate performance of tourism competitiveness in border counties, which is measured by tourism arrivals and revenues. Interior competitiveness can explain the causes of tourism competitiveness formation more specifically, which involves supporting and driving factors of tourism development. The study concludes that in order to provide reference for establishment of scientific strategy on tourism development in border counties, the study of characteristics of competitive factors on spatiotemporal variations and a deep analysis on driving mechanism of different types of border counties should be strengthened in the future. KEYWORD: Border county; Tourism competitiveness; Formation mechanism; Model construction

We demonstrate the first programmable group-delay module based on polarization switching. With a unique binary tuning mechanism, the device can generate any differential group delay value from -45 to +45 ps with a resolution of 1.40 ps, or any true-time-delay value from 0 to 45 ps with a resolution of 0.7 ps. The delay varying speeds for both applications are under 1 ms and can be as fast as 0.1 ms. We evaluate both the dynamic and static performances of the device while paying special attention to its dynamic figures of merit for polarization-mode dispersion emulation and compensation applications. Our experiment shows that the device exhibits a negligible transient-effect induced power penalty (

A necessary and sufficient condition for a convex and compact set of complex polynomials to be strictly Hurwitz is given. The result implies and generalizes several results on strict Hurwitz property of polynomials. In particular, our result covers the “edge theorem” for polytopes of strictly Hurwitz polynomials and requires weaker conditions than the “edge theorem”. It is also shown that previously established results on the robust strict Hurwitzness of diamond polynomials can be implied by our result. Finally, applying the result, we derive a new result on the robust positivity of a complex diamond rational function.

In this paper, a new configuration is proposed that can emulate all-order polarization mode dispersion (PMD) with tunable statistics. The emulator is composed of multiple birefringent crystals separated with magnetooptic (MO) rotators. Unver certain control conditions, these MO rotators can also work as switches, i.e. they can add or cancel the differential group delay (DGD) between adjacent sections by aligning fast axis with either fast axis of slow axis. Thus the emulator can be configured into different crystal combinations with different birefringence and generate PMD with tunable average values. Computer simulations show the effectiveness of the approach with three typical PMD values as well as demonstrating the corresponding 2nd-order PMD.

We propose a novel partial-optical-spectrum degree of polarisation (DOP) measurement that increases the pulse-width dependent differential group delay (DGD) monitoring range for 10, 20, and 40-Gbit/s RZ and sensitivity for 10-Gbit/s NRZ signals. The monitoring range for 20 and 40-Gbit/s RZ signals is extended to one bit time.

In this paper, we propose a constant quality rate allocation algorithm for MPEG-4 FGS (fine granularity scalability) coded video sequences. The rate allocation problem is formulated as a constrained minimization of quality fluctuation. The minimization is solved using a novel composite rate distortion analysis. For a set of video frames, a composite rate distortion curve is first computed and then used for computing the optimal rate allocation. The proposed algorithm is very efficient because it is neither iterative nor recursive. In addition, after the composite rate distortion curve is computed, it can be used to calculate optimal rate allocation for any rate budget. Therefore, it is suitable for FGS coded bitstreams, which need to be transmitted and decoded many times at many different rates. Moreover, the composite rate distortion curve can be updated efficiently over sliding windows. This further reduces the computational complexity. Experiments using both synthetic and real FGS coded videos have shown the effectiveness and the efficiency of the proposed algorithm.

Carrier frequency offset (CFO) is a basic problem arising in many digital communication systems. In this paper, we propose a new adaptive blind CFO estimation scheme. Unlike the cyclic moment CFO estimation (batching processing), the CFO is estimated and tracked using the least square adaptive algorithm. Thus, it can fully cancel the CFO influence, and give a CFO-free estimation of the transmitted sequence. Moreover, it has a capability of tracking the time-varying CFO.

A method of automatically classifying fingerprints into three groups, whorl, loop, and arch is described. It can help medical scientists to study the relationship between fingerprint patterns and medical disorders, such as breast cancer. In the research, a frequency domain approach that uses the feature of Fourier spectrum was developed; that is, prominent peaks in the spectrum give the principal direction of fingerprint patterns. Using the above feature, the authors obtain the principal direction of every subregion. The pattern of the whole image then can be determined. The frequency domain approach allows one to classify whorl faster and is less sensitive to the quality of fingerprint image, but it does not easily allow for the classification of arch and loop when triradii areas are too small. >

Reports research results on contour extraction from high voltage electron microscope (HVEM) images of thick cross section montages of small blood vessels. The previous work on this subject which was based on the conventional edge detection operations combined with edge linking, has proven inadequate to describe the inner structural compartments of microvessels. Here an active contour model (commonly referred to as "Snakes") has been applied to advance the previous work. Active contour models have proven themselves to be a powerful and flexible paradigm for many problems in image understanding, especially in contour extraction from medical images. With the developed energy functions, the active contour is attracted towards the edges under the action of internal forces (describing some elasticity properties of the contour), image forces and external forces by means of minimization of the energy functions. Based on this active model, an effective algorithm is implemented as a powerful tool for 2D contour extraction in the authors' problem for the first time. The results thus obtained turn out to be encouraging. >

This paper presents a digital image watermarking algorithm based on a fractal transform. It embeds the watermark in the spatial domain. The advantage of this algorithm is that it can successfully resist certain geometric attacks such as rotation, translation, flip, stretch, and zoom as well as normal signal processing operations such as JPEG compression. During detection, it does not need the original image to recover the watermark.

This paper introduces a new angle for enhancing the robustness of information symbols embedded in video sequences. The main idea is to apply 3D interleaving to the watermark signal. We first briefly explain the 3D interleaving technique used, then demonstrate the increased robustness of the watermark signal as a result of interleaving. Simulation results are shown for two types of burst errors, 3D error clusters and frame loss.

A multi-wavelength fibre laser whose channel spacing can be dynamically and continuously tuned is demonstrated experimentally. A novel programmable magneto-optic-based DGD module is used as the intra-cavity optical filter to control the wavelength spacing. Channel spacing tunable from 0.4 to 1.6 nm is achieved.

Variable bit rate (VBR) video traffic exhibits high burstiness and long range dependence properties, which, in conjunction with the stringent quality of service (QoS) requirements, pose a great challenge in transporting video traffic over a communication network. The authors propose a QoS guaranteed bandwidth allocation for a given resource utilisation. Simulation and analytical results demonstrate that this scheme provides guaranteed delay and achieves high bandwidth utilisation.

In the above-mentioned work by S. Basu (see ibid., vol.78, p.614-626, 1990), one of the main focal points is the robustness of positive property for a k-variate interval rational function having complex coefficients (hereafter the property is referred to as the PC property). It is concluded that the PC property of the specific 16(2/sup k/)/sup 2/ extreme members of the set can imply the PC property of the set. In this comment, it is proven that the PC property of a k-variate complex interval rational function can be assured by the PC property of its certain 16(2/sup k/) extreme members, which are a proper subset of those 16(2/sup k/)/sup 2/ extreme members defined in the above-mentioned work. >

This paper addresses the nonnegativity constrained spectral factorization problem. In the special case when the unknown object polynomial is symmetric, a recursive scheme is delineated for solving the problem.