Offset Adjustment Research Articles

Data-Driven Algorithms for Real-Time Adaptive Tuning of Offsets in Coordinated Traffic Signal Systems

A real-time adaptive control algorithm for tuning traffic signal offsets in a coordinated traffic signal system is presented. The algorithm described here is used in the Adaptive Control Software-Lite (ACS-Lite) adaptive control system. The algorithm uses a statistical average flow profile of traffic on the coordinated approaches to an intersection to assess when vehicles are arriving during the signal cycle. Alternative offset adjustments are evaluated by calculating how much of this flow profile is being captured by the green phase serving each coordinated approach. The algorithm considers the impact of the offset adjustment on traffic at the local intersection as well as on traffic at adjacent intersections that are also under ACS-Lite control. Simulation tests have quantitatively shown that this tuning approach can improve arterial progression performance relative to the quality of the initial baseline fixed offsets used in a traffic pattern. Several issues and areas for improvement of the algorithm are also identified and discussed.

Prostaglandin E2 Stimulates Fibronectin Expression through EP1 Receptor, Phospholipase C, Protein Kinase Cα, and c-Src Pathway in Primary Cultured Rat Osteoblasts

Fibronectin (Fn) is involved in the early stages of bone formation, and prostaglandin E (PGE) is an important factor regulating osteogenesis. Here we found that PGE(2) enhanced extracellular Fn assembly in rat primary osteoblasts, as shown by immunofluorescence staining and enzyme-linked immunosorbent assay. PGE(2) also increased the protein levels of Fn by using Western blotting analysis. By using pharmacological inhibitors or activators or genetic inhibition by the EP receptor, antisense oligonucleotides revealed that the EP(1) receptor but not other PGE receptors is involved in PGE(2)-mediated up-regulation of Fn. At the mechanistic level, Ca(2+) chelator (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester)), phosphatidylinositol-phospholipase C inhibitor (U73122), or Src inhibitor (PP2) attenuated the PGE(2)-induced Fn expression. Protein kinase C (PKC) inhibitor (GF109203X) also inhibited the potentiating action of PGE(2). Furthermore, treatment with antisense oligonucleotides of various PKC isoforms, including alpha, beta, epsilon, and delta, demonstrated that alpha isozyme plays an important role in the enhancement action of PGE(2) on Fn assembly. Flow cytometry and reverse transcription-PCR showed that PGE(2) and 17-phenyl trinor PGE(2) (EP(1)/EP(3) agonist) increased the surface expression and mRNA level of alpha5 or beta1 integrins. Fn promoter activity was enhanced by PGE(2) and 17-phenyl trinor PGE(2) in cells transfected with pGL2F1900-Luc. Cotransfection with dominant negative mutants of PKCalpha or c-Src inhibited the potentiating action of PGE(2) on Fn promoter activity. Local administration of PGE(2) or 17-phenyl trinor PGE(2) into the metaphysis of the tibia via the implantation of a needle cannula significantly increased the Fn and alpha5beta1 integrin immunostaining and bone volume of secondary spongiosa in tibia. Taken together, our results provided evidence that PGE(2) increased Fn and promoted bone formation in rat osteoblasts via the EP(1)/phospholipase C/PKCalpha/c-Src signaling pathway.

Distributed Route Guidance Systems with Self-Organized Multi-Layered Vector Fields

This paper deals with novel distributed route guidance that cooperates with self-organizing control of traffic signal networks. Self-organizing control of traffic signals provides a fully distributed approach to coordinate a number of signals distributed in a wide area based on local information of traffic flows so that split and offset control parameters between traffic signals are adjusted for efficient traffic flow. The self-organizing route guidance systems (SRGS) concept is introduced for efficient route guidance to facilitate offset adjustment of the self-organizing control of signal networks by self-organizing multilayered vector fields. Simulation demonstrates the effectiveness of the proposal under nonstationary traffic conditions.

Retrieval of Sea Surface Temperature from Space, Based on Modeling of Infrared Radiative Transfer: Capabilities and Limitations

Abstract The retrieval (estimation) of sea surface temperatures (SSTs) from space-based infrared observations is increasingly performed using retrieval coefficients derived from radiative transfer simulations of top-of-atmosphere brightness temperatures (BTs). Typically, an estimate of SST is formed from a weighted combination of BTs at a few wavelengths, plus an offset. This paper addresses two questions about the radiative transfer modeling approach to deriving these weighting and offset coefficients. How precisely specified do the coefficients need to be in order to obtain the required SST accuracy (e.g., scatter <0.3 K in week-average SST, bias <0.1 K)? And how precisely is it actually possible to specify them using current forward models? The conclusions are that weighting coefficients can be obtained with adequate precision, while the offset coefficient will often require an empirical adjustment of the order of a few tenths of a kelvin against validation data. Thus, a rational approach to defining retrieval coefficients is one of radiative transfer modeling followed by offset adjustment. The need for this approach is illustrated from experience in defining SST retrieval schemes for operational meteorological satellites. A strategy is described for obtaining the required offset adjustment, and the paper highlights some of the subtler aspects involved with reference to the example of SST retrievals from the imager on the geostationary satellite GOES-8.

A DC–10 GHz amplifier with digital offset correction

This work presents a SiGe:C wideband amplifier with a binary CMOS counter for digital offset adjustment. The application of the “radix<2” approach to accurate offset correction in a digital calibration loop results in smaller area and less power than common static high-resolution offset correction circuits. The counter bits are weighted with a radix of 1.6, leading to 25% error tolerance, and thus simple circuits and small devices. A BiCMOS test chip in a 0.25-μm-CMOS 200-GHz-SiGe:C technology exhibits a correction accuracy well below the measurement noise floor of 50 μV at only 1 mW additional power consumption. The amplifier operates from DC to 10 GHz on a 3 V supply voltage. Since the adjustment compensates device mismatch, minimum-size transistors can be used. This in turn enhances the RF performance.

On-line monitoring of human prostate cancer cells in a perfusion rotating wall vessel by near-infrared spectroscopy.

PC-3 human prostate cancer cells have been cultivated in a rotating wall vessel in which glucose, lactate, and glutamine profiles were monitored noninvasively and in real time by near-infrared (NIR) spectroscopy. The calibration models were based on off-line spectra from tissue culture experiments described previously (Rhiel et al., Biotechnol Bioeng 77:73-82). Monitoring performance was improved by Fourier filtering of the spectra and initial off-set adjustment. The resulting standard errors of predictions were 0.95, 0.74, and 0.39 mM for glucose, lactate, and glutamine, respectively. The concentration of ammonia could not be accurately measured from the same spectra. In addition, metabolite uptake and production rates were determined for PC-3 prostate cancer cells during exponential growth in batch-mode cultivation. Cells grew with a doubling time of 21 h and consumed glucose and glutamine at rates of 6.8 and 1.8 x 10(-17) mol/cell.s, respectively. This resulted in lactate and ammonia production rates of 11.9 and 1.3 x 10(-17) mol/cell.s, respectively. Compared with other monitoring technologies, this technology has many advantages for spaceflights and stand-alone units; for instance, calibration can be performed at one time and then applied in a reagentless, low-maintenance way at a later time. The resulting concentration information can be incorporated into closed-loop control schemes, thereby leading to better in vitro models of in vivo behavior.

Interface pressure sensor for IVRA and other biomedical applications

The fabrication and testing of a minimally intrusive (2 mm high, 10 mm diameter) biomedical interface pressure sensor are described. Such sensors are needed for the implementation of improved safety features in the next generation of automated intravenous regional anaesthesia (IVRA) systems. The sensor utilizes a structured elastomer as a deflection element sandwiched between the plates of a parallel plate capacitor device. Simple mechanical modifications allow sensitivity and zero offset adjustment. The sensor is housed in a package machined from an engineering polymer. The device is easily calibrated using either a bench-top or an on-body calibration procedure. The device is particularly sensitive to cuff artefacts arising from variations in cuff-wrap tightness and folding of the cuff. As such, it offers some promise for detecting potential hazard conditions which can occur during conventional IVRA procedures. For the purpose of unit conversion, 1 Pa=1 N/m 2, 1 MPa=1 N/mm 2 and 40 kPa≈300 mmHg.

Real-time, high-gain, computer controlled amplifier for optical detection systems

A computer controlled high-gain amplifier has been designed for sensitive detection of optical signals. Based on the use of digital-to-analog converters DACs, the gain and offset of a transimpedance amplifier are adjusted through a computer trying to match ideal amplifier parameters for optical detection with different experimental conditions. The amplifying modules have been developed for optical-rheometry techniques that provide information about the microstructural properties of fluids by measuring optical anisotropies induced by transient flows. Characterization of these programmable gain amplifiers shows that they provide gains and bandwidths more than adequate for experiments involving signals that evolve rapidly and with a large dynamic range. Hence, the use of DACs allows for the possibility of computer controlling both gain and offset in real time, with a significant reduction of the spurious contributions from the amplifying stages during data acquisition. In spite of being designed for optical rheometry, the amplifiers could be useful for any other laboratory arrangements requiring an amplifying stage with real-time gain and offset adjustment capabilities.

Planar-assembly triaxial microaccelerometer with electromechanical sigma-delta ADCS

Abstract By combination of two LIGA-fabricated micromechanical acceleration sensors with a Z -axis sensitive acceleration sensor element, a planar assembly of a triaxial microaccelerometer can be put into practice. In our readout system, each channel consists of a dedicate full-custom ASIC electromechanical sigma-delta modulator and a digital sine 3 ( f ) decimation filter. The output data interface is intended for readout by microcontrollers and digital signal processors (DSPs). Software-programmable reference voltages facilitate self-test and software-controlled range and offset adjustment. Temperature compensation can be performed by reading the output of a temperature-sensing circuit on the sensor head. The measured noise level is 5μg Hz 1/2 at a measuring range of ± 1.5 g. Simulations with a dedicated high-level simulator have shown that the sensitivity can be increased by at least one order of magnitude by optimizing the sigma-delta modulators. As an example for application, an acceleration data logger will be described. Finally, we present the design of an improved accelerometer chipset which consists of a single sensor head chip and an enhanced decimation filter interface.

New kind of fluxgate magnetometer probe with enhanced electronic processing

The design of a new kind of probe, providing the advantages of closed path magnetic circuits, is described in this work. It also provides offset adjustment and a higher directionality as compared with the ring core probes. Signal conditioning circuits for fluxgate magnetometers require synchronization circuits for the pick-up coil second harmonic signal and the reference signals. Any phase difference in such signals will increase the magnitude of errors in the measurement of a magnetic field. A Phase Locked Loop (PLL) has been used to eliminate any possibility of occurrence of a phase difference. Experimental results show that this design may make the system more accurate and reliable, and reduces power consumption.

Forward kinematics solution of Stewart platform using neural networks

The Stewart platform's unique structure presents an interesting problem in its forward kinematics (FK) solution. It involves the solving of a series of simultaneous non-linear equations and, usually, non-unique, multiple sets of solutions are obtained from one set of data. In addition, most effort usually result in having to find the solution of a 16th-order polynomial by means of numerical methods. A simple feed-forward network was trained to recognise the relationship between the input values and the output values of the FK problem and was able to provide the solution around an average error of 1.0 ° and 1.0 mm. By performing a few iterations with an innovative offset adjustment, the performance of the trained network was improved tremendously. Two extra iterations with the offset adjustment reduced the average error of the same trained neural network to 0.017 ° and 0.017 mm.

Planar-assembly triaxial microaccelerometer with electromechanical sigma-delta ADCs

By combination of two LIGA-fabricated micromechanical acceleration sensors with a Z-axis sensitive acceleration sensor element, a planar assembly of a triaxial microaccelerometer can be put into practice. In our readout system, each channel consists of a dedicate full-custom ASIC electromechanical sigma-delta modulator and a digital sine 3( f) decimation filter. The output data interface is intended for readout by microcontrollers and digital signal processors (DSPs). Software-programmable reference voltages facilitate self-test and software-controlled range and offset adjustment. Temperature compensation can be performed by reading the output of a temperature-sensing circuit on the sensor head. The measured noise level is 5μg Hz 1/2 at a measuring range of ± 1.5 g. Simulations with a dedicated high-level simulator have shown that the sensitivity can be increased by at least one order of magnitude by optimizing the sigma-delta modulators. As an example for application, an acceleration data logger will be described. Finally, we present the design of an improved accelerometer chipset which consists of a single sensor head chip and an enhanced decimation filter interface.

A capacitive pressure sensor interface using oversampling Δ-Σ demodulation techniques

An interface for a capacitive pressure sensor which accommodates digital encoding and linearization functions has been developed. The front-end is a switched-capacitor bridge which converts the sensor capacitance into a proportional voltage. This voltage is applied to a pulse-width modulator to be compared with a model signal generated by a digital waveform synthesizer (DWS). This model-based signal processing provides the digital equivalent of the pressure being measured. For high-yield, monolithic implementation of the interface, oversampling /spl Delta/-/spl Sigma/ demodulation techniques are used for the DWS. In addition to the digital functions, offset and scale adjustment, and cross-parameter compensation are also possible with this architecture. A prototype interface is described to demonstrate these capabilities.

Offset adjustment to reduce coding error of interpolative DPCM

AbstractInterpolative DPCM has superior prediction capabilities compared to the commonly used extrapolative DPCM, but since quantization errors accumulate during decoding, and since quantization errors are expanded by expansive coefficients that are proportional to the image size, IDPCM has the weakness that coding errors become excessive. In this paper, offsets are added to the pixel values of the image that is to be coded, where a new method is proposed for the offset adjustments such that a transformed image with smaller quantization errors results. The effectiveness of this algorithm is confirmed by simulations with real images. Since the offset values are determined by the solution of a nonlinear minimization problem with an evaluation function that is the coding error derived from the function of the offsets values and quantization errors of the adjusted image, a minimization algorithm that combines a descent method with a one‐dimensional search and which exploits properties of the evaluation function is used. Furthermore, coded data rates are estimated, and rate‐distortion curves are determined with the use of a hypothesized image probability model. By combining this method with a previously proposed subsampling method, it is possible to improve the image quality by 3 [dB], or reduce the coded rate by 0.3 [bits/pixel].

An offset reduction technique for use with CMOS integrated comparators and amplifiers

Methods for reducing the input offset voltage of comparators and amplifiers are reviewed. A comparator that adjusts its own offset either at power-up or in response to a control input is presented. The nature of the offset adjustment is such that the comparator is capable of continuous-time operation. Room-temperature offset in the range of -100 to +100 mu V are achievable. Adjusted offsets exhibit a temperature coefficient on the order of -1 mu V/ degrees C. >

Methods of improving the images in phase-contrast microscopy: theory and computer simulation

Three methods for improving the image of phase-contrast microscopy are proposed. The first two methods subtract, from the ordinary phase-contrast image, the image obtained through an objective with different pupil functions from that of the ordinary objective. These methods can reduce the distortion due to nonlinearity to less than 1/10 of the ordinary phase-contrast image. The third method simply uses a brighter objective lens along with a television camera with offset adjustment. The brighter lens results in higher sensitivity and less distortion. Theory, computer simulation, and a few experimental results are presented.

Direct estimation of nutation coefficients from VLBI data

Previous analyses of nutation angle errors from Mark III VLBI data have been made by estimating offset corrections to the instantaneous nutation angles from single-day observing sessions. Adjustments to the coefficients of the nutation model were then estimated from the time series of offset corrections. In this paper we estimate the corrections to the nutation series coefficients directly from the multi-year ensemble of data. The resulting corrections have smaller uncertainties than corrections estimated from the daily offsets because the direct solution has many fewer degrees of freedom. We have forced the corrections to occur at the periods of the dominant terms of the IAU 1980 nutation series instead of allowing the pole orientation to vary freely on each day. Results from daily offset adjustment and direct nutation series adjustment from nearly seven years of data agree at the level of the combined one-sigma uncertainties, 0.1 milliarcseconds. The amplitude of the free core nutation was also estimated from the daily offset data; no significant amplitude was observed.

The BEPC focusing X-ray beamline optical design

A focusing X-ray beamline will be built at the Beijing 2.2–2.8 GeV electron-position collider (BEPC). This beamline is intended for diffraction, scattering and other applications. The beamline optical system consists of a right-angle structure monochromator with a laser encoder and a bent platinum coated cylindrical mirror which focuses the radiation with 1 to 1 magnification in the range of 3 to 12 keV. The diffraction and scattering experiments require stability of both the position and angle of the incident beam. Our beamline design incorporates beam monitors and stepping motor controlled motions of the focusing mirror to keep the beam focus point fixed when the electron orbit changes. Computer ray tracing has been done to check the image spot distortion caused by the offset adjustment to compensate the orbit change. The beamline design also has considerable flexibility for further development. As a Phase II plan, the monochromator will include a feedthrough structure to exchange crystals with a plane mirror-grating pair without a break in the vacuum. It will then be possible to extend the spectral range of the beamline of the soft X-ray range.

Video-enhanced contrast polarization (AVEC-POL) microscopy: a new method applied to the detection of birefringence in the motile reticulopodial network of Allogromia laticollaris.

A new method is described for recording rapid processes of cell motility in polarized light. The Allen video-enhanced contrast (AVEC-POL) method of polarization microscopy achieves significant improvements in resolution, contrast, and the visibility of fine detail by a combination of novel adjustments to a standard (unrectified) polarizing microscope and video camera. Using the full working aperture of a high-power planapochromatic objective lens and compensator setting of lambda/9-lambda/4, visible images appear lacking in contrast. However, the same images viewed with an appropriate video camera equipped with an electronic offset adjustment can be made to appear with as much contrast as desired, revealing a significantly greater amount of fine detail in the image than can be seen by high extinction visual microscopy alone. At bias retardations between one-ninth and one-quarter wave, the diffraction anomaly observed near extinction disappears. Consequently, polarizing rectifiers are not required with the AVEC-POL method, and images previously requiring photographic exposures of around 20 seconds are sufficiently bright to be registered on the video monitor in 1/60 second. Using an intensity monitor, quantitative measurements of cellular birefringence can be retrieved from live or videotaped images displaying a linear relationship between contrast and phase retardation due to birefringence. The AVEC-POL method also renders accessible to polarized light analysis a number of objects that scatter or depolarize too much light to be studied by high extinction methods. The method is demonstrated on model objects and applied to the highly motile reticulopodial network of Allogromia laticollaris. Rapid motion in close association with microtubules can now be analyzed in greater detail at a significant reduction in the cost of recording.