Automatic Level Control Research Articles

Air suspension and adaptive damping

Referring to recent body layouts with a high centre of gravity, adaptive damping helps obtaining an enhanced compromise of both driving stability and ride comfort. A conceptual design of a relay mechanism linked to a third shock absorber and its integration in the front axle design of the MCC Smart City-Coupe is presented as a prototype system. The functional verification of this system and its impact on the lateral dynamics are being discussed in comparison to the conventional design, aided by track testing and simulation conducted at the Institut fur Kraftfahrwesen Aachen (Aachen University). Furthermore the layout and the prototype application of a Smart rear-axle air spring system for providing automatic level control and improving passenger comfort is introduced. Its effects on both driving safety and comfort can be shown in relation to the conventional setup.

Discussion of “Flap Gate Design for Automatic Upstream Canal Water Level Control” by Charles M. Burt, Russdon Angold, Mike Lehmkuhl, and Stuart Styles

Discussion of “Flap Gate Design for Automatic Upstream Canal Water Level Control” by Charles M. Burt, Russdon Angold, Mike Lehmkuhl, and Stuart Styles

Closure to “Flap Gate Design for Automatic Upstream Canal Water Level Control” by Charles M. Burt, Russdon Angold, Mike Lehmkuhl, and Stuart Styles

The discussion by Hager is appreciated. Our work was conducted before the Raemy and Hager (1998) paper was published, and we were not aware of its existence when our paper was written. Our work would have benefited from the Raemy and Hager paper (1998) if it had been available then. It is an excellent contribution to the subject, and covers several technical details better than we did, plus it includes some topics that we did not discuss. The solution of the opening moment (couple) for the Raemy and Hager design is simpler than for our design. Raemy and Hager achieved this simplicity by placing their counterweight in a different plane than the flap, enabling them to always have the pivot at the same point— apparently very close to the upstream water surface. In contrast, with our design each gate has a different vertical and horizontal distance between the hinge and the counterweight. We maintain a substantial vertical distance between the hinge (pivot) point and the water surface. From a construction standpoint in California conditions, our design has advantages. First, the bearings with our design are always well above the water level. This is important because the majority of the installations in California use this gate installed inside existing flashboard structures. It would be difficult to install bearings close to the water surface. Furthermore, in silty water one would expect the bearings to be damaged if they are wet. Second, the construction of our design is simple because everything except the bearing assembly is built in the same plane. The vast majority of the construction is done in irrigation district welding shops, where flat-plate construction has definite advantages. Although the opening couples for the Raemy and Hager gate are computed simply and accurately, their results are only for a suppressed sidewall condition. None of the 100+ installations that I am aware of in California have suppressed conditions. The free discharge we see on the sides and bottom complicates the couple computation because the pressure approaches zero on the sides of the flap as it opens, as well as on the bottom and top of the flap. Our pressure distribution testing results were from an unsuppressed condition. The pressure distribution will also change somewhat depending on whether the bottom of the flap (when closed) is on the floor or is elevated above the floor. In general, the installations with our design have the bottom of the flap well above the upstream floor.

Microprocessor-assisted audio signal processing system for VHS VCRs

This paper describes a method of changing the time constant using gain control for playback equalizers and automatic level controller (ALC) of VHS VCRs using microprocessor-assisted processing. In the case of bipolar IC for a standard model, a total of 10 time constants which consist of external results of a VCR developed using this new method significantly reduced these time constants to 2. That is, it was confirmed that this method has an equivalent performance in frequency characteristics and recovery time to the standard model. Moreover, the attack time was shortened to 1/20 of the standard model, therefore the pop noise was decreased. The proposed method is suitable for system on a chip (SOC) using a BiCMOS process.

Flap Gate Design for Automatic Upstream Canal Water Level Control

The EXCEL design procedure for a simple hydraulic flap gate for automatic upstream canal water level control is provided. Basic configurations were developed in The Netherlands in the 1920s and have recently been used in Indonesia, the Dominican Republic, and Nigeria. Four irrigation districts in the San Joaquin Valley of California have constructed and installed over 60 properly functioning flap gates. The gates can be installed within 2 h, but require free discharge conditions and in practice are limited to controlling water depths of about 1 m or less.

A channel-number insensitive erbium-doped fiber amplifier with automatic gain and power regulation function

The design scheme for an erbium-doped fiber amplifier (EDFA) with automatic channel-by-channel gain and power regulation function is discussed with much emphasis on the pump power control scheme and the requirement for feedback circuitry. Based on both wavelength and time-resolved simulation technique, an amplifier repeater employing novel high-speed automatic gain control (AGC) and automatic level control (ALC) functions is designed and implemented. The AGC and ALC scheme can suppress the transient power fluctuation of a surviving channel caused by adding or dropping all other channels less than 0.45 dB and keep output power constant over 9-dB input power range.

Automatic Leveling Control System for Combine

In harvesting rice and barley using combine, the inclination of the body caused by the irregular surface condition of the field and the soil sinking from the unbalanced weight during the grain collection used to make harvesting operation difficult and even impossible. To overcome such a problem, automatic leveling control system for a combine has been developed and tested. The system was composed of the sensor for measuring left and right inclination of the combine chassis and the hydraulic control system. The adaptability of the control system was investigated by analyzing system response in time domain. And the limit angle of the leveling control was set up to be +/- 7°. The proposed control and hydraulic power system was implemented to the prototype combine. The prototype combine was designed and built as a separable structure with chassis and track. This paper shows results of the leveling performance tested in the laboratory and the grain field.

Power excursion suppression in cascades of optical amplifiers with automatic maximum level control

The automatic maximum level control scheme, which automatically selects the maximum power channel as the control channel and keeps its maximum power constant, is the most attractive candidate among gain control techniques applicable to wavelength-division-multiplexed linear repeaters. The design guidelines of this scheme are presented. The power transient response and bit-error-rate performance of the remaining channels during changes in the number of channels are measured in cascades of four repeaters. It is experimentally confirmed that power excursions and power penalties at the bit-error rate of 10/sup -9/ can be suppressed to less than 0.7 dB and less than 0.3 dB, respectively, even when seven out of eight channels are dropped within 1 /spl mu/s.

An integrated CMOS micromechanical resonator high-Q oscillator

A completely monolithic high-Q oscillator, fabricated via a combined CMOS plus surface micromachining technology, is described, for which the oscillation frequency is controlled by a polysilicon micromechanical resonator with the intent of achieving high stability. The operation and performance of micromechanical resonators are modeled, with emphasis on circuit and noise modeling of multiport resonators. A series resonant oscillator design is discussed that utilizes a unique, gain-controllable transresistance sustaining amplifier. We show that in the absence of an automatic level control loop, the closed-loop, steady-state oscillation amplitude of this oscillator depends strongly upon the dc-bias voltage applied to the capacitively driven and sensed /spl mu/resonator. Although the high-Q of the micromechanical resonator does contribute to improved oscillator stability, its limited power-handling ability outweighs the Q benefits and prevents this oscillator from achieving the high short-term stability normally expected of high-Q oscillators.

PLC-based optical add/drop switch with automatic level control

A novel switch configuration for an optical add/drop multiplexer is proposed. By utilizing a certain Mach-Zehnder interferometer both as a component of a double-gate switch and as a level equalizer, we reduced the number of Mach-Zehnder interferometers from five in a conventional switch configuration to three. The add/drop switch simultaneously provides high-isolation switching and polarization-independent automatic level control. The use of planar lightwave circuit (PLC) technology enables this switch to be fabricated with three thermooptic switches (TOSWs) and a monitor tap. High isolation of more than 44 dB and automatic level control accuracy of better than 0.3 dB are achieved. Bit error rate (BER) measurements confirmed switch's usability in the optical add/drop multiplexer.

Method and apparatus for improving effective signal to noise ratios in hearing aids and other communication systems used in noisy environments without loss of spectral information

Improved signal to noise ratio to help speech comprehension in a noisy environment is accomplished by selectively downwardly expanding a speech and noise composite signal when the speech signal is absent, thereby lowering signal components which represent noise. An expansion control signal is extracted from the composite input signal. Operation is based on the assumption that when noise alone is present, the input signal amplitude is less than some reference level and that when speech and noise are present together, the input signal amplitude is greater than the reference level. The response rates of gain changes are quite rapid, and do not introduce distortion or other audibly noticeable artifacts of the processing. The amount of downward expansion of the noise alone is small compared to noise gates to further reduce processing artifacts. The methods of realization include use of, in combination and alone, analog compressors and expanders, analog expanders in combination with voltage clamps and/or automatic level control circuits, two-quadrant multipliers in conjunction with digital control, entirely digital means for obtaining the requisite sensing and gain control, and expandor designs that are analogs of conventional filter designs where the notion of amplitude replaces frequency. Automatic noise suppression may be employed to pre-process the input signal, thereby rendering the control circuit self adjusting for better performance over a wide range of background sound levels. Various microphone, preferably providing directional characteristics, may be used to reduce noise levels in the received input signal.

Sustaining devices for stringed musical instruments

A sustaining device for prolonging the vibration of a string of a stringed musical instrument having a magnetic pickup means responsive to vibration of a string, and an electromagnetic string driver means to provide a magnetic drive force to the string. A cancellation circuit is provided for reducing electromagnetic feedback between the pickup and driver by adjusting the relative phase and amplitude between a first and second pickup signal and combining the signals so that the responses to electromagnetic interference cancel. One embodiment of the cancellation circuit includes a second electromagnetic driver that generates an amplitude-adjusted and phase-adjusted electromagnetic field to cancel electromagnetic interference. The driver may be a section of toroidal solenoid that is shaped so that its endpoles are in close proximity to the string for concentrating magnetic flux along the string. The strings are provided with electrical current which interacts with magnetic flux generated by the driver for driving the string in a second orthogonal plane of vibration. Electromagnetic interference between separate sustain devices is reduced by placing the components of each pickup means equidistant to each of the drivers. Automatic level control means is provided to each of a plurality of sustain devices to minimize the effects of magnetic damping on the strings. A hand-held sustaining device is provided with an encapsulating means for separating the driver from other elements of the device.

Design Study for Continuous Caster Tundish Weight Control and Ladle Steel Flow Estimate

Abstract This paper describes a study into tundish weight control and steel flow estimation at BHP Steel - Long Products Division, Newcastle, NSW, Australia, performed during late 1995. Following upon a previous project to successfully implement automatic mold level control at this installation, a study was made on how to improve the weight control in the tundish and to also improve the estimate of steel flow exiting the ladle. The project involved plant analysis, controller design, Kalman filtering and on-line implementation. The feasibility study successfully achieved its objectives and resulted in some modifications to the existing control system.

Automatic Level Control Circuit for High Power VHF Pulsed Radar Transmitter

An automatic level control circuit has been developed for a 53 MHz 120 kW pulsed transmitter. The novel circuit works for variable pulse repetition frequency and pulse width. It yielded good results for pulse widths as narrow as 1 μ sec and pulse repetition frequency as low as 256 Hz. The circuit maintains output power of 120 kW within ± 0.2 dB and has been successfully used in the Indian MST radar transmitter.

Automatic level control of multiple audio signal sources

An ambiance channel produces an ambiance audio signal as a reference threshold such as from a noise microphone located away from the program microphones. Variable gain amplifiers in a plurality of program channels selectively gate open those program channels that have audio present exceeding the ambiance threshold. When the program channels are below the noise threshold and hence inactive, they are gated off and the background noise in the ambiance channel is shunted around the program channel to the output. A control function circuit adjusts the gain of each of the program channels that have been opened as an inverse function of the number of open mics (called NOM). In another disclosed embodiment, a programmed microcomputer receives as inputs the status signals that represent the gated open or gated off conditions of the program channels. These status signals are processed by a software program in the microcomputer that performs both the functions of gating open individual program channels relative to the background noise level, and setting the gain of each of the program channels according to the NOM function.

An analysis of mode-locked arrays of automatic level control oscillators

The locking region for beat frequency entrained, or mode-locked arrays of discrete microwave oscillators, is exceedingly small, which presents great difficulty in array design. This paper shows that introducing a time-delayed gain control loop can enhance the entrainment region and that this region is maximized for a coupling phase of 90 degrees. For this value of coupling phase the location, size, shape, and orientation of the stable mode locking region is derived for arrays of arbitrary size. A study of the dependence of the stable mode locking region on the number of array elements shows that the region becomes highly eccentric as the number increases, thus making array tuning difficult and causing high sensitivity to particular oscillator tuning errors. The analysis is confirmed with a low frequency realization of a three-element array.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Advanced laboratory electrolyser for production of pure hydrogen

A laboratory scale diaphragmless water electrolyser has been developed for the production of pure hydrogen at a pressure of up to 140 kPa by electrolysis of a KOH solution. Porous electrodes with a nickel catalyst and a copper cover layer serve as cathodes, and nickel sheets as anodes. Modular construction of the electrolyser permits simple combination of its cells into larger units. Thus, up to 20 cells with disc-shaped electrodes of 7 cm in diameter were connected in series and provided with electrolyte manifolds and automatic pressure and electrolyte level control devices. The dimensions of the electrolyte manifolds were optimized on the basis of calculations of parasitic currents. A good agreement between the calculated and measured current efficiencies was found at various cell numbers and total currents.

Speech detector for automatic level control systems

A speech detection circuit uses a peak detector and a valley detector including offset voltages to reliably detect the absence or presence of speech at audio base band level. This circuit provides a pulse train output when speech is detected which may be used to control an automatic gain control circuit.

Wave‐Motion Stability in Canals with Automatic Controllers

Analytical methods are used to obtain criteria for wave-motion stability in canals with automatic feedback controllers. With this purpose the Saint-Venant wave-motion differential equations are linearized, as well as the equation of the discharge through check gates of the canal and the boundary conditions determined by the selected control method. The analysis is done for the COPIBIVAL water level automatic control method, which is more general than the BIVAL water-level control method, well known in France. According to the Nyquist criterion a characteristic function \IF\N(\Is\N) of the closed-loop system is defined, using the Laplace transform of the governing wave-motion equations. The criterion of the wave-motion stability is obtained for the canal with one and more poles, taking into account the influence of the friction forces. The authors also present the study results of the wave-motion stability in canals obtained by numerical simulation, using the nonlinear equations. A comparison between the numerical simulation results and the analytical Nyquist criterion shows good agreement.

The EIC Control System and Mathematical Models for a Large Blast Furnace

This paper introduces the configuration and features of the EIC Electric, Instrumentation, Computer) control system of a large modern blast furnace, as well as the content of the blast furnace mathematical models. It also provides their execution effect. The blast furnace EIC system is a two level automatic control system that consists of three parts:Process Computer (PROCOM).Distributed Control System (DCS) which belongs to instrumentation section, and Programmable Logic Controller (PLC) which belongs to electric control section. The PROCOM is a dual hot backup system.One works on line, the other in hot backup mode. The system can detect faults automatically and switch over automatically. The DCS consists of 9 dual field control section.3 operations with CRT's.3 consoles with CRT's, 2 gateways for communication with process computer and dual high-speed communication bus. The DCS implements two sorts of functions, operating, monitoring, management and control, as well as data acquisition. The electric control system is also a multi-level distributed system including 16 PLCs of various kinds, used for job control, job management and communication with PROCOM respectively. There are 8 blast furnace mathematical models grouped in two parts:1 one-line control algorithm models and 4 off-line algorithm models.