Low-speed System Research Articles

A quantitative comparison among different types of auxiliary slot, auxiliary tooth, and the slot opening in split-pole Vernier machine

The Vernier permanent magnet machine is a high-torque, low-speed system suitable for direct-drive applications such as in-wheel electrical machines and wind generation turbines. In this paper, specific critical parameters of the electrical machine for auxiliary tooth and slot are investigated in different conditions. It should be noted that all the models are fully optimized and compared under the same condition by FEA analysis. The results illustrate that the stator with α ≠ β = θ is the best choice for stator split pole. Also, the concentrated winding is wound around the main stator tooth and the magnets mounted on the rotor surface. Besides, all essential characteristics for an electric machine such as torque, cogging torque, power factor, and efficiency are investigated. Furthermore, many basic formulas for designing a Vernier machine are proposed. This comparison helps designers choose the best combination among α, β, and θ in the split-pole structures. There is a nomenclature to organize this manuscript for the reader. It should be noted that all the figures are baked by ANSYS Electronics Maxwell version 19.0. Moreover, all of them are modified by Origin software to show with high quality.

Investigation on Lubrication State of Sliding Bearings in Low-Speed Rotor System Subjected to Torque Load

In order to study the influence of torque load on the lubrication and wear of the sliding bearing of the rigid rotor system, the theoretical and experimental researches on the single-span rotor system with low speed were carried out. A special force sensor was used to measure the bearing load under different torque excitations, and the oil film pressure was calculated. The oil film pressure and thickness of sliding bearing under low speed (210r/min) were simulated by combining the lubrication theory. Based on the film thickness ratio theory, the corresponding relationship between the lubrication state and the torque load value was deduced. In addition, the wear rate and abrasive grain morphology of sliding bearing with different torque values were analyzed by means of oil sample preparation to verify this correspondence. The results show that the film thickness ratio has a logarithmic function relationship with the constant torque load, and the film thickness ratio curve can be used to determine the corresponding torque values under different lubrication states. The wear rate under mixed lubrication state increases exponentially with the torque load, and the main wear mechanism is adhesive wear and abrasive wear. The research results have certain guiding significance to the adjustment of the actual running condition of sliding bearing and its life prediction.

An Agile Electrical Capacitance Tomography System With Improved Frame Rates

In this paper, an AC-based agile parallel hardware system was introduced for ECT. A multi-frequency excitation and measurement strategy was proposed to minimize the switching time between different channels. For an ECT sensor with $2^{m}$ electrodes, all the mutual capacitances can be measured much faster, which is $m$ /( $2^{m}-1$ ) of the time used by the classical single-frequency excitation and measurement strategy. It implies that the proposed strategy accelerates the capacitance acquisition in an exponential way. Besides the efforts made to reduce the switching times between channels, the operating time of each electronic switch was selected to fasten the demodulation. The hardware fabricated here can be modified agilely by running codes, and different excitation and demodulation methods can be implemented on the chip. To verify the performance of the agile system, ECT sensors with different electrodes are facilitated to measure the mutual capacitances. The capacitances can be achieved with a frame rate of respectively up to 15.15 kilo frames per second (kfps) and 12.82 kfps in the cases of 12 and 16 electrodes. The ignition process of a flame generated by a Bunsen burner can be captured by the proposed system. Also, the discharging of the igniter can be imaged, and it is usually undistinguishable in a low-speed system.

A Spatial Analysis Approach for Evaluating the Service Capability of Urban Greenways—A Case Study in Wuhan

A greenway is a low-speed road system built on high-level afforestation, and this system serves as a venue for sightseeing, relaxation, and exercise. In China, greenway planning and construction have been actively and successfully implemented to strengthen the construction of urban human settlements. However, a specific method has yet to be used to assess the service capability of urban greenways. On the basis of geographic information systems and geographical spatial data, we propose an approach to evaluate the overall service capability of urban greenways based on three different aspects. In the first aspect, a buffer-based service-level analysis method is applied to statistically analyze population and residential quarter areas within a greenway service coverage area. This aspect can also indicate the service level and scope of urban greenways. In the second aspect, minimum distance-based accessibility analysis method is utilized for the graduation statistics of residential quarter areas in different ranges of reach distance. This aspect can further reveal the service convenience of urban greenways. In the third aspect, a calculation model is built on the basis of regular grids, to analyze the value of comprehensive service capability in each grid, and to produce a spatial distribution map of the comprehensive service capability of urban greenways. This aspect can describe the service quality of urban greenways. The analysis results of these aspects can be integrated to identify service conditions in which an urban greenway is available to urban populations and residential zones, and to obtain the comprehensive service capability value of greenways. This approach can also emphasize the limitations of greenway construction, and thus help urban planners and decision-makers create optimized urban greenway designs.

Qualitative Recognition of Typical Loads in Low-Speed Rotor System

While the load variations within the low speed rotor systems affect the operating conditions and mechanical properties, they may also provide information on machine faults. Therefore, load recognition is of great significance in operational monitoring for detecting early warning signs of failure and diagnosing faults. In this paper, five types of typical loads in a low-speed rotor system are qualitatively analyzed. Moreover, a method is presented based on the vibration signals from a low-speed rotor system using the ensemble empirical mode decomposition (EEMD), energy feature extraction, and backpropagation neural network (BPNN). A low-speed rotor test bench was designed and manufactured for load recognition and an experiment was set up based on certain load characteristics. Loading tests for five representative categories were conducted and various vibration signals were collected simultaneously. The EEMD was shown to eliminate the mode mixing seen in traditional EMD, which resulted in a clear decomposition of the signal. Finally, the characteristics were imported into a BPNN after energy feature extraction, and the different types of load were accurately recognized. Comparing the experimental results to existing data, a total recognition rate of 92.38% was achieved, demonstrating that the proposed method is both reliable and efficient.

Accuracy of the non-relativistic approximation to relativistic probability densities for a low-speed weak-gravity system

The Newtonian and general-relativistic position and velocity probability densities, which are calculated from the same initial Gaussian ensemble of trajectories using the same system parameters, are compared for a low-speed weak-gravity bouncing ball system. The Newtonian approximation to the general-relativistic probability densities does not always break down rapidly if the trajectories in the ensembles are chaotic -- the rapid breakdown occurs only if the initial position and velocity standard deviations are sufficiently small. This result is in contrast to the previously studied single-trajectory case where the Newtonian approximation to a general-relativistic trajectory will always break down rapidly if the two trajectories are chaotic. Similar rapid breakdown of the Newtonian approximation to the general-relativistic probability densities should also occur for other low-speed weak-gravity chaotic systems since it is due to sensitivity to the small difference between the two dynamical theories at low speed and weak gravity. For the bouncing ball system, the breakdown of the Newtonian approximation is transient because the Newtonian and general-relativistic probability densities eventually converge to invariant densities which are close in agreement.

A New Testing System of Missile-Target Encounter Based on Doppler Fuse

With the purpose of reducing cost, improving the operability, and ensuring the safety, a low-speed testing system of the encounter of fuse and target was carried out. When the system working, the relative velocity of the target and fuse is in control in less than 10m/s, which is a shrink ratio of the real encounter. Experimental investigation shows that the low-speed encountering system can reach the requirements of Doppler radio fuse in the early design, which can help designers design a better fuse.

Low-Speed Common Rail Diesel Engine Electronic Control System Structure and Working Principle in Electrical Control Engineering

The performance of Diesel engine control system influence the engine combination property directly. The traditional mechanical control system can't meet the requirements of the fuel consumption and emissions. We should turn to the advanced electronic control system. This article introduced the basic frame and control mode of low-speed common rail diesel engine electronic control system, and according to the control object, the whole control system is divided into different modules to detailed analysis.

Statistical Predictions for the Dynamics of a Low-Speed System: Newtonian versus Special-Relativistic Mechanics

The Newtonian and special-relativistic statistical predictions for the mean, standard deviation and probability density function of the position and momentum are compared for the periodically-delta-kicked particle at low speed. Contrary to expectation, we find that the statistical predictions, which are calculated from the same parameters and initial Gaussian ensemble of trajectories, do not always agree if the initial ensemble is sufficiently well-localized in phase space. Moreover, the breakdown of agreement is very fast if the trajectories in the ensemble are chaotic, but very slow if the trajectories in the ensemble are non-chaotic. The breakdown of agreement implies that special-relativistic mechanics must be used, instead of the standard practice of using Newtonian mechanics, to correctly calculate the statistical predictions for the dynamics of a low-speed system.

Comparison of Newtonian and Special-Relativistic Trajectories with the General-Relativistic Trajectory for a Low-Speed Weak-Gravity System

We show, contrary to expectation, that the trajectory predicted by general-relativistic mechanics for a low-speed weak-gravity system is not always well-approximated by the trajectories predicted by special-relativistic and Newtonian mechanics for the same parameters and initial conditions. If the system is dissipative, the breakdown of agreement occurs for chaotic trajectories only. If the system is non-dissipative, the breakdown of agreement occurs for chaotic trajectories and non-chaotic trajectories. The agreement breaks down slowly for non-chaotic trajectories but rapidly for chaotic trajectories. When the predictions are different, general-relativistic mechanics must therefore be used, instead of special-relativistic mechanics (Newtonian mechanics), to correctly study the dynamics of a weak-gravity system (a low-speed weak-gravity system).

Mixed-Signal Parallel Compressive Spectrum Sensing for Cognitive Radios

Wideband spectrum sensing for cognitive radios requires very demanding analog-to-digital conversion (ADC) speed and dynamic range. In this paper, a mixed-signal parallel compressive sensing architecture is developed to realize wideband spectrum sensing for cognitive radios at sub-Nqyuist rates by exploiting the sparsity in current frequency usage. Overlapping windowed integrators are used for analog basis expansion, that provides flexible filter nulls for clock leakage spur rejection. A low-speed experimental system, built with off-the-shelf components, is presented. The impact of circuit nonidealities is considered in detail, providing insight for a future integrated circuit implementation.

Pulsed laser scalloping of decorative lace

Decorative lace is knitted in webs typically 3 metres wide containing many smaller lace ribbons. These lace ribbons must be separated from the main web before sale to the garment manufacturers and retail trade. The separation process for decorative lace is traditionally carried out using scissors or a guided knife cutting system. The development of a machine vision guided laser cutting system at Loughborough University in the 1990s demonstrated that an economical fully automatic cutting system could replace the slow and expensive traditional methods. Incorrect positioning of the continuous wave laser beam focused spot can cause melting and subsequent hardening to the lace edge, which can feel harsh on the skin of the garment wearer and is a quality issue in some market sectors. In order to address this quality issue a high-accuracy pulsed laser cutting solution has been investigated, resulting in a fully automatic, vision guided, pulsed laser cutting process for lace in the form of a low-speed demonstration system. The lace produced on the pulsed laser system has been shown to have a significant improvement in edge quality over lace produced using the continuous wave laser cutting process. The edge quality produced by the pulsed laser cutting process approaches that of traditional mechanically cut lace with the potential for vastly increased output with lower operational costs.

Low-Speed System for Digital Coding of a Speech Signal

Basic problems in the field of low-speed digital speech transmission are briefly described. Analysis of the existing methods of digital speech coding was used to propose a system for adaptive processing of the speech signal. A generalized scheme for compression of the speech signal using a neuron network is presented.

Limitation of stimulated Raman scattering cancellation in WDM systems via spectral inversion

Crosstalk arising from stimulated Raman scattering may be cancelled by spectral inversion for low-speed wavelength-division-multiplexing (WDM) systems. By evaluating the crosstalk variance, the limitation of the method is provided in term of the allowable walkoff length, limiting to low-speed system with long walkoff length up to hundred of kilometers.

The power line carrier communication control module

The power line carrier (PLC) communication control module is described. This module, which supports physical and data link layers, is based on the Japanese technical standard for a low-speed system. It provides useful functions for composing a home control system. All the circuits of the module are included in one compact (58 mm*38 mm) hybrid integrated circuit. An application system was also developed on the basis of the module.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Microprocessor-Based Multichannel Transient Recorder

Data acquisition of fast time varying transient phenomena relevant to structural dynamics and aerodynamic wind tunnel testing pose a number of problems such as speed, retrieval of data for analysis, number of channels, etc. To overcome these limitations, a software-based high-speed Multichannel Transient Data Acquisition system has been designed and developed. This system is built around the Burr-Brown SDM-853 Module. The data are stored in 16-kbyte MOS RAM memory. The stored data are retrieved by a low-speed system clock through a digital-to-analog converter (DAC) onto an X-Y/t plotter for hard copy.

Cultivation of the Bacteriel Strain Achromobacter delicatulus, Producing an Exocellular Polyglucan-Type Polysaccharide in the Fermentation Tank FU-6

Growth processes and biosynthesis of the exocellular polyglucan-type polysaccharide, produced by the bacteria Achromobacter delicatulus, were studied in the laboratory fermentation apparatus FU-6 under three completely different aeration systems. The purpose of this study was to find the most economical way of the polysaccharide biosynthesis. The growth rate and the synthesis of the exopolysaccharide were not limited either by the oxygen transfer or glucose content under the conditions examined. The best construction proved to be the fermentation tank with the lowspeed agitation system. In the case of the bacterial strain Achromobacter delicatulus, producing huge amounts of the thick slimy polyglucan exopolysaccharide, the industrial production may develop without any principal technical difficulties.

Magnetic Suspension for Low-Speed Vehicles

Several forms of novel suspension systems for passenger-carrying vehicles are currently being investigated throughout the world. Most of these, however, are aimed at high-speed, intercity transport systems, and comparatively less development work has been undertaken to provide a new form of low-speed system for urban-transportation. The possibility of using controlled direct-current electromagnets for low-speed (up to 70 kph) vehicle suspension has been explored in this paper. This system, also known as ferromagnetic or attraction suspension system, offers a very attractive combination of design simplicity, low operating and maintenance costs, high reliability and virtually silent operation. This system is also considered to have capital costs comparable with alternative forms of urban-transport systems and could be designed to fit into the existing fabric of cities and towns. The feasibility of the d-c system is illustrated here through analytical and experimental results of the ride and track-clearance characteristics for a single-degree of freedom suspension system. These results are used to formulate a procedure for designing a multimagnet vehicle suspension system. Main design and performance criteria for maglev vehicles are discussed in the context of experimental results obtained from test vehicles. Engineering aspects of some of the system components have been presented with a view to evaluating their suitability for low-speed systems.

Electron temperature in the upper F -region

The Ariel I satellite, which was launched on 26 April 1962, carried two Langmuir probes to measure the density and temperature of the ionospheric electrons. The experimental technique and the physical arrangement of the probes have been described in detail in the preceding paper (Bowen, Boyd, Henderson &amp; Willmore 1964) and only further details relevant to the measurements presented in this paper will be discussed here. The properties of the ionosphere are deduced from the first and second derivatives with respect to probe voltage of the probe current/voltage characteristic, these two quantities being transmitted in real time by the satellite telemetry system. In addition, some information from each voltage sweep of each of the probes was processed by a low-speed encoder and recorded on the satellite tape recorder for subsequent transmission when within range of a telemetry station. In this way data recorded over an entire orbit were obtained irrespective of the distribution of the telemetry stations. This paper describes the analysis of electron temperature data from the low-speed system. 2. The Storage and Processing of the Probe Measurements The low-speed encoder sampled each of two information channels from each probe during a period of 30.72 s. Since the probe sweep period was 55 s each channel was sampled once or twice during the sweep. One of the channels was used to determine the maximum modulation depth reached in the sweep of the probe curve, while the other was used to record the maximum value of the first derivative of the probe current characteristic. These quantities were determined by diode peak-reading circuits and retained in capacitor memories whose storage time was much greater than the sweep period. Temporary local storage of the information was necessary both because the presentation of the maximum value of the two parameters could not be synchronized with the encoder sampling, and because the information was sampled continuously for an interval of 0.48 s, during which time a large change in modulation depth could occur. Thus the capacitor store was required to retain the information for a time which could be as large as the interval between encoder samples.

`MOPTS' A Mobile Photographic Tracking System

The MOPTS is a high accuracy, smooth, low-speed and high-speed mobile photographic tracking system which introduces new concepts in the development of guided range ground-instrumentation. The system was designed and developed by the American Machine and Foundry Company of Stamford, Conn., for the U. S. Naval Missile Center, Point Mugu, Calif, for use on the Pacific Missile Range. MOPTS is a mobile, astrodome-covered, two-axis mount which has a design goal of 20 seconds of arc accuracy with a low-speed capability of 10 seconds/second and a high-speed of 80 degrees/second, with acceleration of 120 degrees/second/second. This paper describes design characteristics of the system and covers the problems encountered in development of a high precision mount with a dynamic range in excess of 15,000: 1 as required for a high accuracy mobile mount such as MOPTS.