Broadband Digital Networks Research Articles

Calculating algorithm of service quality statistical parameters for asynchronous network subscribers

It is often necessary to determine statistical parameters that characterize the quality of service on the network by managing when designing computer networks using the concept of virtual connections with bypass directions. In many ways, the attainable level of quality of the services provided is determined at the stage of network design, when decisions was made regarding the subscriber capacity of stations, the capacity of bundles of trunk lines, the composition and volume of telecommunication services provided. Despite constant progress in the field of network technologies, the problem of determining the necessary amount of network resources and ensuring the quality of user service remains relevant. In this regard, this article discusses a broadband digital network with service integration, based on an asynchronous network in which an iterative method implemented. Here the flow distribution is determined by the route matrix, and the load distribution between the nodes of each pair of nodes made through the path tree obtained on the matrix of routes when calculating this pair. At the same time, an algorithm has been built for allow optimal allocation of channel resources between circuit switching and packet switching subnets within an asynchronous network.

Load Distribution and Determination of Loss Probability in Asynchronous Network

In this paper, a general description of the problem of calculating probability–time characteristics was presented. At the initial stage of studying this problem, we studied the asynchronous data transmission of the constituent broadband digital network with the integration of services for both the channel switching subnetwork and the packet switching subnetwork. And also the circuit switching subnetwork was investigated using the bypass of the direction of transmission of the stream of multi-channel calls. At the same time, the source data of the problem of calculating probabilistic characteristics were set for the channel switching subnetwork, the characteristics that were determined during the solution of the problem were listed, and some assumptions were described that made it possible to adequately approximate the study of such a model to the functioning of a real network. Next, a mathematical model for calculating the loss probabilities was described, both for communication channels and for nodes of the channel switching subnetwork included in the asynchronous transfer mode network. The model of information traffic transmission is presented, where the method is implemented using network bypass directions. A method has been developed for generating a nodal load of a channel switching subnet and a system of equations has been obtained, the solution of which determines the value of a nodal load relative to the probability of loss on communication channels and proved the uniqueness of the solution of this system of equations.

Strong motion PGA prediction for southwestern China from small earthquake records

Abstract. For regions without enough strong ground motion records, a seismology-based method is adopted to predict motion PGA (peak ground acceleration) values on rock sites with parameters from small earthquake data, recorded by regional broadband digital monitoring networks. Sichuan and Yunnan regions in southwestern China are selected for this case study. Five regional parameters of source spectrum and attenuation are acquired from a joint inversion by the micro-genetic algorithm. PGAs are predicted for earthquakes with moment magnitude (Mw) 5.0, 6.0, and 7.0 respectively and a series of distances. The result is compared with limited regional strong motion data in the corresponding interval Mw ± 0.5. Most of the results ideally pass through the data clusters, except the case of Mw7.0 in the Sichuan region, which shows an obvious slow attenuation due to a lack of observed data from larger earthquakes (Mw ≥ 7.0). For further application, the parameters are adopted in strong motion synthesis at two near-fault stations during the great Wenchuan Earthquake M8.0 in 2008.

Kappa(<i>κ</i>) from Records of Small Earthquakes in North China

At high frequencies, there is an obvious descending of Fourier spectrum amplitude of ground motion acceleration. This fact could be described by a low0pass filter that is controlled by parameter Kappa (κ). In most regions of the world, there are not sufficient strong ground motion records to evaluate this regional parameter. We try to acquire κ value from small-earthquake records of the broadband digital seismograph network in North China (36°-43°N, 113°-120°E). Total 1995 records from 28 small earthquakes (Mw=3.5-4.5) recorded at 155 stations of China Earthquake Network during February of 2002 to September of 2012, are analyzed. The κ value is acquired from the slope rate of the decay segment of the calculated Fourier spectrum of each record, and the mean value is obtained. The result is analyzed if κ is magnitude, focal depth or distance dependent. For the magnitude-dependence, κ values of 40 strong ground motion records are also obtained and compared. The result of the paper shows that κ is not magnitude-dependent neither focal depth-dependent. The distance-dependent is not obvious, especially for small earthquake.

Ground Motion Prediction Equation for Lanzhou Region from Small Earthquake Records

By small earthquake records from the Gansu broadband digital earthquake network, five regional source and crustal medium parameters, stress drop Δσ, quality factor parameters Q0 and η, geometrical spreading parameters R1 and R2, are inversed for the Lanzhou area. Envelops of Fourier spectra are adopted as the objective function, the values of those parameters are 34.625bars, 95.665, 0.360, 58.188km and 105.650km, respectively. These values are adopted to calculate Fourier amplitude spectra, and complex spectra are formed by combining with random phase spectra. Acceleration time histories can be simulated, and PGAs on different moment magnitude-distance pairs are obtained previously. Compared with several observed strong ground motion data, the result is lower in the case of Mw=5.0, passes through the data in the case of Mw=6.0 and higher than the record of Mw=7.0. It is adopted in regional seismic zonation. Compared with The Zonation Map of Earthquake Ground Motion Parameters in China (GB18306-2001), the result is close to the map when PGA is lower than 0.2g.

Depth of mid-crustal discontinuity from reflected seismic waves on local earthquake seismograms recorded at Shillong Plateau, Northeast India

In this study, an attempt is made to estimate the depth of mid-crustal discontinuity beneath the Shillong Plateau in northeast India region using broadband seismogram of local earthquakes. Principle of the technique is to relate the seismic travel times of the reflected phases (SxS) with the crustal thickness above the discontinuity. Though mid-crustal discontinuity (or Conrad discontinuity) is reported in some parts of the world, no such study was undertaken in the present study area due to complexity in analogue seismograms recorded before 2001. The digital waveforms of the local seismic events recorded by broadband digital network in the study area, however, make it possible precise detection of the seismic phases that are reflected at this discontinuity. The results show that the mid-crustal discontinuity exists at a depth 18±0.5 km beneath the Shillong Plateau, which provide a better understanding of the crustal velocity structure of the region for future study.

Estimating the Magnitude of Historical Earthquakes from Macroseismic Intensity Data: New Relationships for the Volcanic Region of Mount Etna (Italy)

The historical activity of Mt. Etna is well documented by a large amount of sources that have reported the seismic and volcanic phenomena occurring on the volcano since the late 1600s (Azzaro et al. 2000; Branca and Del Carlo 2005). Such a large dataset of historical information is not common and is comparable, in Italy, to that of Vesuvius (Giudicepietro et al. 2010). As for long-term seismicity known through macroseismic data, the first release of the historical catalog of Mt. Etna earthquakes from 1832 to 1998 was published ten years ago (hereinafter CMTE catalog) and since then has been regularly updated (CMTE Working Group 2008). With 1,790 earthquakes listed, the CMTE catalog provides an overall picture of the space-time evolution of the major seismicity and possible relationships with past eruptive activity ( e.g. , Azzaro and Barbano 1996; Azzaro et al. 2001). On the other hand, it was only in 1967 that the first seismograph station was installed at Etna. A complete seismograph network began to operate in the early 1980s with nine short-period analog stations, evolving in the last decade into a broadband digital seismograph network consisting of some 30 stations (Patane et al. 2004). For a long time, this network has operated without uniform coverage of the volcano, since it was largely aimed at monitoring eruptive activity in the middle-upper parts of Etna; such a situation has meant favoring the macroseismic approach in studying the severely damaging earthquakes that struck the populated slopes of the volcano. As a consequence, this typology of data has been used for defining the seismotectonic features (Azzaro 2004) and seismic hazard of this area (Azzaro et al. 2008). In the seismic catalogs the estimation of magnitude for earthquakes occurring in the pre-instrumental period is obtained through empirical relationships using the value …

Crustal structure of the northeastern Tibetan plateau, the Ordos block and the Sichuan basin from ambient noise tomography

We apply ambient noise tomography to significant seismic data resources in a region including the northeastern Tibetan plateau, the Ordos block and the Sichuan basin. The seismic data come from about 160 stations of the provincial broadband digital seismograph networks of China. Ambient noise cross-correlations are performed on the data recorded between 2007 and 2009 and high quality inter-station Rayleigh phase velocity dispersion curves are obtained between periods of 6 s to 35 s. Resulting Rayleigh wave phase velocity maps possess a lateral resolution between 100 km and 200 km. The phase velocities at short periods ( 25 s), strong high velocity anomalies are observed within the Ordos block and the Sichuan basin and low phase velocities are imaged in the northeastern Tibetan plateau, reflecting the variation of crustal thickness from the Tibetan plateau to the neighboring regions in the east. Crustal and uppermost mantle shear wave velocities vary strongly between the Tibetan plateau, the Sichuan basin and the Ordos block. The Ordos block and the Sichuan basin are dominated by high shear wave velocities in the crust and uppermost mantle. There is a triangle-shaped low velocity zone located in the northeastern Tibetan plateau, whose width narrows towards the eastern margin of the plateau. No low velocity zone is apparent beneath the Qinling orogen, suggesting that mass may not be able to flow eastward through the boundary between the Ordos block and the Sichuan basin in the crust and uppermost mantle.

Surface-Wave Studies beneath the Pacific Ocean

The fundamental mode Rayleigh, R2, and R3 waves were used to study the phase velocity tomography and surface-wave attenuation variation beneath the Pacific Ocean. The Rayleigh-wave phase velocity estimation for about 4000 propagation paths across the Pacific Ocean were made at time periods of 70, 100, 150, and 230 sec. More than 100 earthquakes, which occurred in the Pacific Ocean and were recorded at about 60 broadband digital seismic networks ascribed to IRIS, OHP, TERRAscope, Pacific 21 (formerly POSEIDON), and the Pacific Northwest Region (UW), are used in this study. The resulting phase velocity maps at varying periods showed a good correlation with known geological and tectonic features of the region. A fast-velocity anomaly is surrounded by a slow-velocity anomaly over the eastern and western parts of the Pacific Ocean, while the central part is associated with a fast-velocity anomaly. Subduction zones and spreading regions are demarcated by slow-velocity anomalies. A slow-velocity anomaly is also clearly visible over the Hawaiian hot spots and the French Polynesia, Micronesia, Japan, and Java–Sumatra trench axis zones. A high-attenuation zone (low Q -value) is visible over the East Pacific rise and Nazca plate and Cocos plate regions of younger lithospheric age, and a low-attenuation anomaly (high Q -value) marks the zones of older lithosphere in the western part of the Pacific Ocean. High-attenuation regions are surrounded by low-attenuation zones in the eastern and western Pacific Ocean. Subduction zones with lower attenuation are flanked by high-attenuation anomalies on both sides, reflecting the plate interaction. The hot spots are associated with a high-attenuation zone of the Pacific Ocean at a depth of 100–300 km.

Redefining the Diamond Cutting Edge: A Technique that Complements Nano-Metric Surface Generation

ABSTRACT Ongoing developments in broadband digital networks and optical devices require mechanical components having nano-metric surface finishes and ultra precision shapes. Such components are processed using the technology of diamond micro-machining in which diamond tools are extensively used. However, these tools are susceptible to chemical attack at high temperatures and induce severe wear, especially when cutting ferrous materials. As a result, these diamond tools need to be redefined (i.e., resharpened) on a regular basis in order to facilitate micro-cutting and to generate nano-metric surface finishes. This paper describes a new way of diamond tool edge re-sharpening and its conditions to achieve both increased accuracy and material removal rate.

Near-real-time Seismic Moment-tensor Determination in Spain

The increasing number of broadband telemetered seismic stations installed recently in Spain makes it possible to provide seismic parameters beyond location and magnitude estimates, in near real-time. In particular, we describe new near-real-time calculations of the seismic moment tensor (SMT). The SMT provides information about the parameters inherent to the physical process at the source. A rapid SMT determination thus provides an estimate of the scalar seismic moment ( M ) and therefore the moment magnitude ( M ); it also characterizes the type of faulting and fault orientation. This key information can be useful for emergency response in the case of a destructive earthquake. Gilbert (1973) presented early efforts to invert for the SMT using Green's functions to represent path response. Since then, SMT inversion has been carried out increasingly routinely using teleseismic recordings of intermediate- to large-magnitude earthquakes. The recent introduction of modern broadband digital regional networks has made it possible to develop SMT inversion techniques for smaller-magnitude earthquakes at regional distances (Dreger and Helmberger, 1993; Romanowicz et al. , 1993; Nabelek and Xia, 1995; Randall et al. , 1995; Thio and Kanamori, 1995; Ammon et al. , 1998). Several institutions now routinely calculate the SMT for many earthquakes, for example the U.S. National Earthquake Information Center (Sipkin, 1982) and Harvard University (Dziewonski et al. , 1981). On the regional level and close to real-time, the University of California at Berkeley has developed a procedure to determine the SMT that has been used since the 1990's ( e.g. , Romanowicz et al. , 1993; Pasyanos et al. , 1996). This procedure involves a double inversion in the time and frequency domains of Love and Rayleigh surface waves, producing automatic results approximately five minutes after the origin time. This procedure has been integrated within the REDI …

Coding, decoding, and recovery of clock synchronization in digital multiplexing system

High-speed broadband digital communication networks rely on digital multiplexing technology where clock synchronization, including processing, transmission, and recovery of the clock, is the critical technique. This paper interprets the process of clock synchronization in multiplexing systems as quantizing and coding the information of clock synchronization, interprets clock justification as timing sigma-delta modulation (T/spl Delta/-/spl Sigma/M), and interprets the jitter of justification as quantization error. As a result, decreasing the quantization error is equivalent to decreasing the jitter of justification. Using this theory, the paper studies the existing jitter-reducing techniques in transmitters and receivers, presents some techniques that can decrease the quantization error (justification jitter) in digital multiplexing systems, and presents a new method of clock recovery.

Broadband and the baby bells

Wireless access may be the way to get around the phone and cable monopolies. New rules adopted by the U.S. Federal Communications Commission (FCC) in February may: (A) Reboot the stalled U.S. telecommunications industry by spurring the construction of broadband digital subscriber line (DSL) and fiber telephone networks. (B) Kill any chance of a competitive DSL market in the United States, prolonging the telecom sector's malaise. (C) Be largely irrelevant to broadband's future in the United States, as decisions due later this year from the FCC will matter much more to the growth of true high-speed networks.

Autoregressive Model Using Fuzzy C-Regression Model Clustering for Traffic Modeling.

A robust traffic modeling is required to perform an effective congestion control for the broad band digital network. An autoregressive model using a fuzzy c-regression model (FCRM) clustering is proposed for a traffic modeling. This is a simpler modeling method than previous methods. The experiments show that the proposed method is more robust for traffic modeling than the previous method.

Comparative digital holography

We described a method for direct holographic comparison of the shape or the deformation of two objects when it is not necessary that both samples be located at the same place. In contrast to the well-known incoherent techniques based on inverse fringe projection, this new approach uses a coherent mask that is imaged onto a sample object that has a microstructure different from that of the master object. The coherent mask is created by digital holography to permit instant access to complete optical information on the master object at any wanted place. Transmission of the digital master holograms to the relevant places can be made with a broadband digital telecommunication network such as the Internet.

The estimation of stable distribution parameters from teletraffic data

This article is concerned with the estimation of the parameters that describe a stable distribution from teletraffic data. Stable distributions are characterized by four parameters that can be estimated using a number of methods. This article provides an introduction to the stable distribution and a summary of some of the estimation techniques developed for them. It presents a comprehensive performance comparison between four techniques and a study of how these techniques can be applied to real data. The data under consideration is that expected on broadband digital networks.

A newly emerging customer premises paradigm for delivery of network-based services

Low-speed home networks in some form are used for lighting, appliance control and security systems in over 20% of U.S. households. The increasing penetration of personal computers (PCs) is leading to early deployment of twisted-pair Ethernet networks by information industry employees and early technology adopters. Digital video has matured to the point where the power of the MPEG compression algorithm is bearing fruit in new consumer electronics. The “jury is still out” on ultimate convergence of the entertainment center and the PC. However, it has definitely progressed with the advent of television Web appliances, and with the addition of video attributes being pulled down from Web sites and played on the PC. Rather than think of convergence in the context of a single-user device with full capability, increasing use of advanced digital networks in the home is the more likely evolution, with devices optimized for their particular task easily connecting to a whole-house network through attractive wall plates, by wireless, or through their commercial a.c. power cords. Several industries are formulating such concepts, examining advanced broadband digital networks with “plug-and-play” capabilities. For network service providers competing in an increasingly unregulated environment, success of service delivery will come to depend on a well-thought-out strategy for service termination. The old paradigm of “customer premises equipment” which was relatively well defined, specified and controlled by the network operator will give way to home networks which are extremely sophisticated in their own right. Service providers will be forced to think in terms of delivering services into this local environment, with an interface which is more driven by the customer's local deployment decisions, somewhat analogous to the business environment today in which carriers provide trunks and private lines to PBXs and gateways. This paper will examine the trends in home networking, and propose architectures which service providers can use to deliver services to, and across, home networks, to end-user devices. We will discuss recent industry activity focused on the concept of a residential gateway (RG), an electronic device which mediates between different service-provider access networks and different devices and networks within the home. We will discuss how the RG can facilitate intelligent testing capabilities to reduce maintenance costs, and intelligent provisioning which can support flexible service capabilities.

Beamspace adaptive array antenna for broadband signals

In this paper, we propose a beamspace adaptive array antenna for broadband signals with a wide fractional bandwidth. The proposed beamspace adaptive array antenna has a multiple digital beamforming network that preserves spectral components of input broadband signals by using tapped-delay-line circuits. Coefficients of the tapped-delay-line circuits are determined such that each broadband digital beamforming network has the same phase characteristics, and the beam pattern including sidelobe and null characteristics is virtually frequency independent. A few adaptive weights, which are linear combination coefficients of the selected broadband beams, follow a beam selector. The number of adaptive weights for the proposed adaptive array is considerably less than that of an element space structure with tapped-delay-line circuits. We demonstrate by computer simulation that interference suppression by the proposed beamspace adaptive array is as good as that of an element space adaptive array and that it has much faster convergence. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(10): 38–48, 1997

Beamspace adaptive array antenna for broadband signals

In this paper, we propose a beamspace adaptive array antenna for broadband signals with a wide fractional bandwidth. The proposed beamspace adaptive array antenna has a multiple digital beamforming network that preserves spectral components of input broadband signals by using tapped-delay-line circuits. Coefficients of the tapped-delay-line circuits are determined such that each broadband digital beamforming network has the same phase characteristics, and the beam pattern including sidelobe and null characteristics is virtually frequency independent. A few adaptive weights, which are linear combination coefficients of the selected broadband beams, follow a beam selector. The number of adaptive weights for the proposed adaptive array is considerably less than that of an element space structure with tapped-delay-line circuits. We demonstrate by computer simulation that interference suppression by the proposed beamspace adaptive array is as good as that of an element space adaptive array and that it has much faster convergence. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(10): 38–48, 1997

A study of the Barisakho, Georgia, earthquake of 1992 October 23 from broad-band surface and body waves

SUMMARY We study the 1992 October Georgian earthquake located in the centra) part of the Great Caucasus. This is the last strong (Ms = 6.5) shallow earthquake of a Series of three that struck this region in the two-year period of 1991-1992. In order to determine the source parameters we analysed surface and body waves from the IRIS and GEOSCOPE very broad-band digital networks. The fundamental mode of surface waves was retrieved using frequency-time analysis (FTAN), a technique that makes inversion more stable and enables the measurement of the spectral features from the signal in the presence of stationary noise. We used long-period surface waves (60-150 s) to obtain the seismic moment (Mo =4.8~10'~ N m) and the focal mechanism (strike 8=300, dip 6 = 15 and rake A= 135). The space-time distribution of the source moment density tensor was determined from intermediate-period (35-60 s) surface waves. We found the following results: duration = 6 s, rupture velocity = 3.2 km s-I, major and minor axes of the fault surface I,,, = 32 km and Zmin = 20 km, respectively. For the inversion of body waves we performed a shape waveform modelling using the gradient method of NabElek. We considered the source as a point source of 6 s duration. The results of body-wave inversion (Mo = 3.0~ 10 N m, 8 = 300°, 6 = 17 and 1 = 137) are in good agreement with estimates from surface waves. One of the nodal planes of the fault-plane solution corresponds to a thrust fault which agrees with the general seismotectonic features of the region of the Kartli and Kokheti ridges in the central part of the Great Caucasus. The southern slope of the Great Caucasus strikes WNW-ESE and the underlying crystalline basement plunges towards the NNE under the main axial zone. The source plane coincides with the location of the contact between the crystalline basement and the upper-block overthrust.