Search

At present, it is highly relevant to improve the safety of transport and pedestrians by crossing their paths at different levels. At the same time, to cross wide highways, it is rational to design pedestrian bridges without intermediate supports, namely suspension and cable-stayed bridges. In addition, numerous studies have confirmed the feasibility of using fiber-reinforced plastic (FRP) as a material for load-bearing structures. However, in order to massively introduce FRP suspension bridge designs into production, it is necessary to improve the method of designing suspension bridges, which has been used mainly on steel and reinforced concrete bridges for decades. Therefore, the paper describes theoretical and experimental studies of strength, flexural stiffness (calculations are made taking into account geometric nonlinearity), as well as the aerodynamic stability of structures of single-span suspension bridges with main beams made of polymer composite materials. As a result of the research, the feasibility of designing FRP bridge structures within the framework of the adaptation concept was confirmed. The obtained conclusions will serve to improve the method of calculating suspension bridges with main beams made of polymer composites.

The paper considers approaches to ontologies using in task of requirements tracing. It is stated that for successful requirements management it is necessary to reveal the image of rational activity object, not its individual properties. In this approach requirement is defined as an aspect projection of some object ontology onto considered subject area in the system purpose context. A model of the activity object ontology, as a system of functionally and logically interrelated concepts, quantities and methods, is developed. Proposed model combines an ontology of quantities and measures and an ontology of means, “technologies” of assessment. Such model makes it possible to describe processes occurring in the system in more detail, and in combination with other ontologies (ontology of an activity life cycle stages, properties ontology, certain project ontology constructed by project documentation), it allows to obtain tools for more efficient requirements revealing, understanding of causal relationship in their changing and management.

Urban forests have great ecological value as facilities for maintaining a favourable environment for the life of citizens. The development of industrial production and increased traffic flows lead to air pollution in cities, which contributes to a decrease in the productivity of tree stands, an increase in their decline and a decrease in their growth. The aim of this paper is to analyze the growth and productivity of larch stands under different anthropogenic influences and to develop recommendations for increasing their stability and durability. The materials for the study were data from the repeated measurements of permanent inventory plots at the Experimental Forest District of the Russian State Agrarian University – Moscow ‘Timiryazev’ Agricultural Academy and forest areas of the Moscow Region. The growth of stands of mean height in the permanent inventory plots does not correspond to the scale of site class determination: first, the forest site index is upgraded, and then it is declined. The results of the analysis of growth and productivity of larch stands have shown that these trees can be recommended for use in urban landscaping as they demonstrate high resistance to adverse effects. Mixed pine-larch stands are the most promising for urban landscaping. Key words: Larch stands, urbanized environment, growth, productivity.

The method of the synthesis of multi-channel decentralized variable structure system for the control of quadrotor spatial motion is developed in this paper. The control law based on the formation of the sliding mode in the separate subsystems of each coordinates control is formed. Each subsystem includes two loops for Cartesian coordinates and relevant Euler angles control. The conditions of the existence of stable sliding mode are obtained. These conditions take into account essential dynamic reciprocal effect between all control channels. The application of proposed control law provides high control quality and maximal fast-action at any variations of the quadrotor parameters within given ranges. This control law does not require the identification of changing object parameters. Efficiency of synthesized control system is confirmed by numerical simulation results. The control system can be realized in the real time by simple technical means.

We experimentally demonstrate multigigabit capacity bidirectional hybrid fiber-wireless systems with RF carrier frequencies at the W-band (75–110 GHz) that enables the seamless convergence between wireless and fiber-optic data transmission systems in access networks. In this study, we evaluate the transmission performances in two scenarios: a fiber-wireless access link that directly provide high-speed connections to wireless end users, and a fiber-wireless-fiber signal relay where a high capacity wireless link can be used to bridge two access fiber spans over physical obstacles. In both scenarios, we compare the transmission performances in terms of achievable wireless distances with and without using a high-frequency electrical power amplifier at the wireless transmitter. A downlink 16-Gbit/s QPSK signal and an uplink 1.25-Gbit/s ASK signal transmission over the two implementations are experimentally evaluated in terms of bit-error-rate (BER) performance. Results show that the use of the power amplifier can extend the wireless distance from ∼1 m to over 15 m in an indoor environment with BER performance within the 7% FEC threshold.

We report on the performance of channel and source coding applied for an experimentally realized hybrid fiber-wireless W-band link. Error control coding performance is presented for a wireless propagation distance of 3 m and 20 km fiber transmission. We report on peak signal-to-noise ratio performance of several encoded high-definition video sequences constrained by the channel bitrate and the packet size. We argue that light video compression and low complexity channel coding for the W-band fiber-wireless link enable low-delay multiple channel 1080p wireless HD video transmission.

Simultaneous 60-GHz radio over fiber upconversion and fiber transmission of lightwaves produced by an external cavity laser, a distributed feedback laser, and a C-band vertical cavity surface emitting laser are demonstrated. The 1.25-Gb/s data are transmitted concurrently on each of the lightwaves attaining a bit error rate performance

The next generation of information technology demands both high capacity and mobility for applications such as high speed wireless access capable of supporting broadband services. The transport of ...

Demonstration and comparison study for V-and W-band real-time high-definition video delivery in diverse fiber-wireless infrastructure

New methods of the synthesis of multi-dimensional robust and adaptive control systems for the centralized control of the spatial motion of autonomous underwater vehicles (AUV) is developed in this paper, such as variable structure system (VSS) and self-adjustment system with reference model. The conditions of the sliding mode existence and the self-adjustment process stability with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The application of synthesized discontinuous control provides the high control quality at any variations of the object parameters within the given ranges.

In this paper, we review our experimental and simulation work on 28- and 56-Gbaud PAM4-based 100Gbps and 400Gbps short-haul links, including 10, 40, and 80km transmission distances. We also discuss the system performances, limitations, and areas of improvement for these links and their future applications.

The variable structure system with control signal saturation for the position control of second order dynamic object is considered in this paper. The features of system phase trajectories and transition processes at different values of control law coefficients are analyzed. The new conditions of a sliding mode existence in the given areas of a phase plane are formulated. The control systems parameters ensuring the greatest possible fast-action and high dynamic precision are determined. The received conclusions are confirmed by results of control system numerical simulation.

The application of variable structure system with sliding mode and saturation in a task of position control of second order dynamic object is considered in this paper. The features of system behaviour at different values of control law coefficients are analyzed. The new conditions of a sliding mode existence in the given areas of a phase plane are formulated and strictly proved. The control systems parameters ensuring the greatest possible fast-action and high dynamic precision are determined. The received conclusions are confirmed by results of control system numerical simulation.

By using an N×M multicast switch, where N is expandable from 4 to ≥16, and M is 16, we experimentally demonstrate that in a metro optical network with OSNR ≥17dB, the sensitivity of an intradyne coherent receiver can reach < −34dBm for 28Gbaud DP-QPSK signals, thereby enabling a CDC ROADM with no drop-side EDFAs.

We propose an approach for dynamic channel allocation and multicast data delivery inside the 60 GHz unlicensed band. Channels, conveying 1.25 Gbps signals, can be allocated on demand by tuning the frequency sweep of an external cavity laser (ECL) either in the optical remote node (RN) or in the central office (CO). At the RN, we perform the replication of the original channel suitable for closely spaced multicast applications such as high definition (HD) video delivery where RN serves as a photonic radio frequency (RF) generator for both channel allocation and multicast. Experimental demonstration is presented with bit error rate (BER) performance below 10-9 for original and replicated channels after transmission through 22.8 km of standard single mode fiber (SSMF).

We propose a simple wireless access point for hybrid access networks and experimentally demonstrate bidirectional operation in W-Band. Photonic up-conversion and electrical downconversion are used in the downlink, while in the uplink both up- and down-conversion are conducted by electrical means.

We explore mechanical properties of top down fabricated, singly clamped inverted conical GaAs nanowires. Combining nanowire lengths of 2-9 $\mu$m with foot diameters of 36-935 nm yields fundamental flexural eigenmodes spanning two orders of magnitude from 200 kHz to 42 MHz. We extract a size-independent value of Young's modulus of (45$\pm$3) GPa. With foot diameters down to a few tens of nanometers, the investigated nanowires are promising candidates for ultra-flexible and ultra-sensitive nanomechanical devices.

We experimentally demonstrate uncompressed high-definition (HD) video distribution at 84 GHz Radio over Fiber link achieving up to 3 meters of wireless transmission. We experimentally emulate Metro-Access architecture by deploying single/multimode fibers. Passive and active approaches for remote antenna unit (RAU) are experimentally investigated. The bit error rate (BER) performance of the optical and wireless channels is reported. A successful transmission of uncompressed HD video in the W-band wireless channel is demonstrated with prospects to pave the way for application-focused fiber-wireless connectivity supported by diverse optical fiber distribution infrastructure.

We experimentally investigate the 60 GHz double-sideband radio-over-fiber link. We present the bit error rate performance of the system for HD video transmission in the access architecture and the phase noise measurements for metro-access scenarios.

In this paper, we propose and experimentally demonstrate a simple, cost-effective hybrid gigabit fiber-wireless system for in-building wireless access. Simplicity and cost-effectiveness are achieved in all parts of the system by utilizing direct laser modulation, optical frequency up-conversion, combined single mode/multimode fiber transmission and envelope detection. Error-free transmission of 2-Gbps data in 60-GHz band over a composite channel including 10-km standard single-mode fiber (SSMF)/1-km multimode fiber (MMF) and 6.5-m air transmission was successfully achieved. © 2012 Elsevier Inc. All rights reserved.

This paper presents the results of experimental and numerical investigations of cooling effectiveness of the film cooled turbine nozzle. The nozzle is with two internal cavities. Front cavity of the nozzle is fed with high pressure cooling air from compressor diffuser with minimal losses of pressure for ensuring film cooling of the leading edge. Rear cavity is with impingement tube for high effective convective cooling. Experimental measurements of cooling flow capacity and cooling effectiveness were carried out on experimental facility of OSC “NPO CKTI”. Investigations included isothermal internal flow tests and hot tests with internal flow and metal temperature measurements. Test results were compared with flow and thermal field CFD predictions. Temperature fields of body and platforms of nozzle were predicted by conjugate heat transfer simulation. Computation domain includes vane-to-vane path flow, vane solid body with shrouds and holes for cooling air injection. Heat transfer conditions inside vane were calculated with one dimension internal flow model. Isothermal internal flow test results were used to validate one dimension internal flow model. Comparison of the experimental and simulation results enabled to modify calculation models to obtain good agreement. Turbine vane temperature fields calculations in different operation conditions were carried out with validated numerical models.Copyright © 2011 by ASME

[EN] The paper addresses the problem of distribution of highdefinition video over fiber-wireless networks. The physical layer architecture with the low complexity envelope detection solution is investigated. We present both experimental studies and simulation of high quality high-definition compressed video transmission over 60 GHz fiberwireless link. Using advanced video coding we satisfy low complexity and low delay constraints, meanwhile preserving the superb video quality after significantly extended wireless distance. © 2011 Optical Society of America., This work has been partly funded by the European Commission under FP7 ICT-249142 FIVER project and by the by the Spanish Ministry of Science and Innovation under the TEC2009-14250 ULTRADEF project.

The new method of the synthesis of multidimensional adaptive control system with reference model self-adjustment for the centralized control of the spatial motion of autonomous underwater vehicles is developed in this paper. The conditions of the self-adjustment process stability with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The application of synthesized control laws allow to provide the high control quality at any variations of the object parameters within the given ranges. The amplitude of self-adjustment signal and energy losses in self-adjustment loop are reduced essentially in the proposed control system. The efficiency of control laws is confirmed by numerical simulation results.

The method of the synthesis of multi-channel adaptive variable structure system with the sliding mode for the centralized control of spatial motion of the nonstationary linear object is developed in this paper. The conditions of the existences of stable sliding mode with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The new law of the adaptive adjustment of the position of sliding hyper-surfaces in each control channel is proposed and mathematically substantiated. The application of these control laws allow to provide the high control quality and the maximally possible fast-action at any variations of the object parameters within the given ranges. The efficiency of synthesized control system is confirmed by numerical simulation results.

The new method of the synthesis of multi-channel adaptive variable structure system with the sliding mode for the centralized control of the spatial motion of autonomous underwater vehicles is developed in this paper. The conditions of the existences of stable sliding mode on the intersection of hyper-surfaces in the space of the system coordinates with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The new law of the adaptive tuning of the position of sliding hyper-surfaces in each control channel is proposed and mathematically substantiated. The application of these control laws allow to provide the high control quality and the maximally possible fast-action at any variations of the object parameters within the given ranges. The efficiency of synthesized control system is confirmed by numerical simulation results.

The method of the synthesis of multi-channel adaptive variable structure system with the sliding mode for the centralized control of spatial motion of the nonstationary linear object is developed in this paper. The conditions of the existences of stable sliding mode with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The new law of the adaptive adjustment of the position of sliding hyper-surfaces in each control channel is proposed and mathematically substantiated. The application of these control laws allow to provide the high control quality and the maximally possible fast-action at any variations of the object parameters within the given ranges. The efficiency of synthesized control system is confirmed by numerical simulation results.

The new method of the synthesis of multi-channel variable structure system with the sliding mode for the centralized control of the spatial motion of autonomous underwater vehicles is developed in this paper. The conditions of the existences of stable sliding mode on the intersection of hyper-surfaces in the space of the system coordinates with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The application of a new control law allow to provide the high control quality at any variations of the object parameters within the given ranges. The efficiency of synthesized control system is confirmed by numerical simulation results.

The multi-channel variable structure system with the sliding mode for the centralized control of the spatial motion of the complex mechatronic object is synthesized in this paper. The conditions of the existences of stable sliding mode on the intersection of hyper-surfaces in the space of the system coordinates with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The new method of explosive control signals formation is developed. The application of control law proposed allow to provide the high control quality at any variations of the object parameters within the given ranges.

A method of adaptive system synthesis for the control of autonomous underwater vehicle spatial motion is developed. A special nonlinear correcting devices is offered. This devices allows to compensate the complete dynamical coupling and kinematic correlations between this vehicle degrees of mobility at constant control object parameters. An adaptive self-adjustment is used in order to compensate the arbitrary variations of this parameters and external perturbances. The efficiency of synthesised control system is confirmed by numerical simulation.Copyright © 2002 by ASME

We present an experimental investigation of the 60 GHz optical carrier suppressed radio over fiber systems with less than 5 dB carrier suppression. As a case study, the 60 GHz RoF signal is generated using a 12.5 Gb/s commercially available Mach-Zehnder modulator biased at its minimum point. We report on error free transmission over 20 km of standard single mode fiber and 1 m of wireless distance. Furthermore, the efficiency of photonic RF generation depending on the value of carrier suppression is reported. We argue that transport of RoF signals with low carrier suppression assisted with simplified techniques of lightwave generation, baseband data modulation, and RF downconversion might be a promising enabling technology for fiber support of close-proximity wireless terminals.

We propose and experimentally demonstrate a fiber-wireless transmission system for optimized delivery of 60-GHz radio frequency (RF) signals through picocell mobile backhaul connections. We identify advantages of 60-GHz links for utilization in short-range mobile backhaul through feasibility analysis and comparison with an alternative E-band (60-90 GHz) technology. The 60-GHz fiber-wireless-fiber setup is then introduced: two spans of up to 20 km of optical fiber are deployed and bridged by up to 4 m of wireless distance. The 60-GHz radio-over-fiber technology is utilized in the first span of fiber transmission. The system is simplified and tailored for delivery of on-off keying data signals by employing a single module for lightwave generation and modulation combined with a simplified RF downconversion technique by envelope detection. Data signals of 1.25 Gb/s are transmitted, and a bit-error-rate performance below the 7% overhead forward-error-correction limit is achieved for a range of potential fiber deployment scenarios. A spurious free dynamic range of 73 dB-Hz2/3 is attained for a frequency-doubling photonic RF upconversion technique. The power budget margin that is required to extend the wireless transmission distance from 4 m to a few hundred meters has been taken into account in the setup design, and the techniques to extend the wireless distance are analyzed. © 2013 IEEE., Manuscript received July 5, 2013; revised July 29, 2013; accepted July 30, 2013. Date of current version August 20, 2013. The work of J. J. Vegas Olmos was supported in part by the Marie Curie Program through the WISCON project. M. Beltran and R. Llorente were supported by the Spain National Plan TEC2012-38558-C02-01 MODAL project. Corresponding author: A. Lebedev (e-mail: alele@fotonik.dtu.dk).

We experimentally investigate the performance of 60 GHz double sideband (DSB) radio over fiber (RoF) links that employ dispersion compensating fiber (DCF). Error free transmission of 3 Gbps signals over 1 m of wireless distance is reported. In order to overcome experimentally observed chromatic dispersion (CD) induced power fading of radio frequency (RF) signal, we propose a method for improvement of RF carrier-to-noise (C/N) ratio through introduction of a degree of RF frequency tunability. Overall results improve important aspects of directly modulated RoF systems and demonstrate the feasibility of high carrier frequency and wide bandwidth RF signals delivery in RoF links including DCF fiber. Error free performance that we obtain for 3 Gbps amplitude shift-keying (ASK) signals enables uncompressed high-definition 1080p video delivery.

Hybrid fiber-wireless transmission of 2-Gbps signals in 60-GHz band over a composite channel (10-km SMF/1-km MMF/6.5-m wireless) is experimentally demonstrated for gigabit in-building wireless access using simple direct modulation, optical upconversion and envelope detection.

This paper presents a performance assessment of 60-GHz mm-wave signal generation using photonic upconversion employing a VCSEL as source. The system reaches 10-9 BER over a variety of optical fibers for data rates of 1.25-Gbit/s.

We present a 10-meter bidirectional fiber-wireless-fiber system at 81/86-GHz (W-band). The fiber transmission amounts for 36-km, whereas the wireless transmission for 10-m, achieving BER performance below the 7% FEC limit for both downstream and upstream.

We demonstrate that, by jointly optimizing video coding and radio-over-fibre transmission, we extend the reach of 60-GHz wireless distribution of high-quality high-definition video satisfying low complexity and low delay constraints, while preserving superb video quality.