Bridge Output Research Articles

Influence of Piping on On-Line Continuous Weighing of Materials inside Process Equipment: Theoretical Analysis and Experimental Verification

Due to the continuity and complexity of chemical systems, piping and operating conditions will have a significant effect on the on-line continuous weighing of materials inside process equipment. In this paper, a mathematical model of the weighing system considering piping and operating conditions was established based on the gas–liquid continuous heat transfer weighing process. A theoretical criterion which can be extended to any continuous weighing system of the materials inside equipment with connected piping is obtained through the mechanical derivation between the material mass, the cantilever beam deflection, the strain gage deformation, and the bridge output voltage. This criterion can effectively predict the influence of piping on weighing results with specific accuracy, and provide a basis for engineering optimization design. On this basis, a set of gas–liquid continuous contact weighing devices was built. The static/dynamic experimental results showed that the accuracy of the system meets the set requirements.

A novel soft-start method for SVG based on D-axis orientation

In this paper, a novel method for shock-free soft-start is proposed. The novel method can realize the aim of no-overshoot and inrush of current during the entire soft-start process, thus the start process is safe, stable, and reliable. When the uncontrolled rectification stage ends, a sinusoidal signal synchronized with the grid voltage is generated through dq coordinate transformation and D-axis orientation, then the signal is transmitted to the three-phase inverter bridge. The AC voltage output of the inverter bridge is superimposed on both ends of the soft-start resistor along with the grid. The open-loop control method is adopted to gradually reduce the modulation ratio of the sinusoidal PWM wave until the capacitor voltage on the DC side reaches the rated voltage value, then the soft-start resistor is removed, which means the shock-free soft-start process is completed. Experimental results prove the effectiveness and feasibility of the control strategy proposed in this paper.

Design and Development of Wireless Electronic Flow Transmitter Using Circular IDC as Primary Sensor

An Internet of Things (IoT) node-based nonintrusive, resilient liquid flow transmitter has been developed using a circular interdigital capacitor (IDC) as a primary sensor. A section of polyvinyl chloride (PVC) pipe is cut and a silicon tube of lesser diameter (compared with PVC pipe) is attached with the PVC pipe. A circular IDC is installed on the silicon tube and is used to convert the volumetric flow rate into corresponding capacitance. The change in capacitance with respect to the flow rate is nonlinear. Modified De Sauty bridge circuit is connected with the developed flow sensor to get the electrical output. To linearize the bridge output, three different linearization techniques, i.e., linear least square (LLS), genetic algorithm (GA), and artificial neural network (ANN) have been used and their statistical analysis is reported in this article. The best suited linearization technique (ANN) for the proposed sensor from the simulated result has been used in hardware implementation. This article proposes the IDC sensor access scheme design based on the IoT node and the transmission of the standard voltage signal 1–5 V using IoT node. The transmitted voltage and the received voltage have the same characteristic under the percentage error of ±0.5% of transmitted voltage. It has 0.286-pF resolution for measurement of liquid flow rate from 0 to 2000 litre per hour (LPH). This article highlights the theoretical analysis of the developed sensor to elucidate its working with maximum clarity. This sensor has been tested and its characteristics are thoroughly studied in the research workshop. Experimental results have proved that the wireless flow transmitter obeys linear characteristics and tuned well with theoretical equations based on the working principle. In addition, the proposed flow measurement is nonintrusive in nature as the circular IDC does not come in contact with the liquid flow, hence, increases the life span of the sensor.

Modification of De’ Sauty Bridge Network for Accurate Measurement of Process Variables by Variable Parameter Transducers

In variable parameter transducers, the small change in passive parameters such as resistance, capacitance, and inductance, generally changes linearly with the process variable in process plant. The classical method of measurement of passive parameters generally uses an ac bridge circuit. However, this type of bridge measurement technique suffers from errors due to the effect of stray capacitances in between bridge output terminals and ground. These errors can be minimized by using the Wagner-earth technique, but the limitation is the repetition of bridge balance, which is required in every observation so that continuous measurement is not possible, which is the basic needs of a transducer. In this article, a modified De’ Sauty bridge network has been developed by using a high-gain operational amplifier to minimize the stray capacitances in case of measurement of the small change in resistances or capacitances. A potentiometer has been used to adjust the sensitivity of the bridge. For a particular value of bridge sensitivity factor, the change of passive parameters of sensor equivalent and the change of actual process variables have been observed and found good linearity and repeatability.

A New Frame-Based Calibration Method for Extended Octagonal Ring Transducers

HighlightsA simple frame was built to hold and apply uniaxial and biaxial loads to octagonal ring transducers for calibration.Similar results were obtained with the frame as with a universal tensile testing machine.The transducer outputs exhibited low cross-sensitivities and hysteresis (=0.4%), and R2 = 0.9998.The frame is portable and safe, and its concept can be adapted to take a wide range of non-gravitational loads.Abstract. An extended octagonal ring transducer (EORT) is a simple, single, and compact biaxial force measuring transducer, which is ideal for soil force measurement in tillage tool research. Calibration of EORTs is needed to ascertain their sensitivities and to determine an accurate calibration equation to convert voltage output to force measurement. Typically, calibration of EORTs involves the use of universal tensile testing machines, hydraulic systems and large gravitational loads (hanging weights) to apply loads. In this study, a simple calibration frame that enables application of non-gravitational loads was evaluated and used to hold and calibrate an EORT through both uniaxial and biaxial loading. The frame was suitable for both uniaxial and biaxial application of offset coincident force up to 3000 N and centered perpendicular force up to 1500 N. The EORT exhibited a strong linear relationship (R2 = 0.9998) between applied forces and voltage outputs, low hysteresis errors (=0.4%), and low cross-sensitivities (3.61% and 1.6% for coincident and perpendicular forces, respectively). Calibration equations developed from the primary bridge output data or from the biaxial loading data using the frame produced good force predictions, which also improved when taking into account the impacts of cross-sensitivity. The results confirmed that this calibration approach can integrate the interactions of output cross-sensitivity to deliver more accurate force prediction. Coefficients of determination of the relationships between applied and predicted forces were 0.9993 to 0.9996 and 0.9877 to 0.9984 for coincident and perpendicular forces, respectively. This calibration frame presents potential for safely applying large, non-gravitational loads in a contained and portable manner and its concept can easily be adapted to suit the scale of the transducer. Keywords: Biaxial loading, Cross-sensitivity, EORT calibration, Offset coincident force, Uniaxial loading.

A novel high-accuracy platinum resistance flexible temperature chain for polar temperature field measurement

In order to effectively improve the accuracy of temperature measurement in the low temperature environment of the polar ice sheet, we designed a multi-point platinum resistance flexible temperature chain based on Pt1000, which has the advantages of low temperature resistance, low power consumption and high accuracy. The temperature chain consists of a master and multiple slaves. The master is used to read the entire temperature chain's data and make data exchange with the external equipment. The slave is used to collect and upload temperature data. RS485 bus communication is used between the master and slaves. The slave circuit directly measures the ratio of the bridge output voltage to the bridge input voltage to calculate the final temperature value, so the measurement accuracy is not affected by the fluctuation of the external power supply voltage. After the temperature measurement unit of each slave is calibrated using the least square method, when the temperature is greater than 0̂C, the temperature measurement error does not exceed 0.00134̂C, and when the temperature is less than 0̂C, the error does not exceed 0.07235̂C. In addition, low temperature experiments indoor as well as field tests have shown that the overall reliability of the temperature chain is higher for simultaneous temperature measurement at multiple points in the low temperature environment, which is suitable for detecting the temperature field profile of glacial ice and snow in the polar environment.

Single-Switch Open-Circuit Diagnosis Method Based on Average Voltage Vector for Three-Level T-Type Inverter

Fault-tolerant control strategy plays a significant role in improving the reliability of three-level T-type inverter where fault diagnosis method is the key and a research hotspot. Load power factor variation and modulation index regulation have great effect on conventional load current based diagnosis methods. Therefore, this article proposes a novel voltage vector based method for single-switch open-circuit fault diagnosis in three-level T-type inverter. Average output voltage vector calculated by voltages between dc-link neutral-point and bridge output terminals is taken as the eigenvector in the procedure and failed switch can be located by three diagnosis variables including angle of eigenvector, normalized modulus of eigenvector, and neutral-point potential. These variables will be some certain values under circuit fault, which are defined as eigenvalues. The vector trajectory prediction technology is utilized for threshold setting, by which the diagnosis is suitable for different power factors and different modulation indices. The strategy of redundant vector replacement is applied to realize fault-tolerant operation and verifying the proposed scheme. Simulations and experiments are carried out to illustrate the superiorities of the proposal.

REDUCED SWITCH TOPOLOGIES FOR MULTI LEVEL INVERTERS WITH M-CARRIER SPWM

This paper presents the transformer based multilevel inverter topologies with a m-carrier based level shift sinusoidal pulse width modulation method. Two topologies are presented in which the first topology has two bridges, one gives quasi square wave output and the other gives pulse width waveform. The outputs of two bridges are energized with the two different ratio transformers. The secondary terminals of two transformers are cascaded to attain 19 level output voltage wave form. The second topology has only one bridge and it contains 8 switches and two DC sources. The bridge output is given to the transformer and it acts as an isolation. The output of the topology gives the 7-level output. This topology has less number of components to reduce the cost and provides inbuilt isolation, to enhance the reliability of converter. The paper uses the common level shift SPWM method with modified carrier that is m-carrier to attain the maximum amplitude and the harmonics are shifted to very high level without change in the frequency. The paper topologies are validated with experimental results.

Temperature Effect and Its Compensation of a Micromachined 2-D Anemometer

This paper presents a semi-empirical model for the temperature effect of a micromachined 2-D anemometer. The anemometer consists of a self-heated double Wheatstone bridge. Eight thermistors are symmetrically arranged in two orthogonal directions, and four of them in each direction make up a Wheatstone bridge. The eight thermistors simultaneously act as both heating and sensing elements. The terminal voltage across the bridge and the bridge output voltage, under the constant current supply, are utilized to measure the wind speed and direction, respectively. The semi-empirical model has taken the thermal physical properties of the air, sensor substrate, and thermistors into account. It shows that the measurement of wind direction has a weak temperature dependence due to the symmetric config uration of the self-heated double Wheatstone bridge, which suppresses the temperature drift. The temperature compensation has been performed by means of the semi-empirical model. The experimental measurements demonstrate that, when the air temperature changes from 270 to 310 K, the wind speed varies from 0 to 30 m/s with an error less than ±1.5 m/s while the wind direction spans from 0° to 360° with the weak temperature dependence.

A 0.1-nW–1-$\mu$ W Energy-Efficient All-Dynamic Versatile Capacitance-to-Digital Converter

A versatile, low-power, and energy-efficient capacitance-to-digital converter (CDC) for Internet-of-Things (IoT) is presented, based on an all-dynamic architecture with adaptable speed, resolution, and range. The proposed CDC includes a single-armed capacitive bridge and a differential switched-capacitor 10-b asynchronous successive approximation register (SAR) analog-to-digital-converter (ADC). The bridge output is directly sampled by the ADC through fully passive correlated-double-sampling (CDS) approach, which enables a fully dynamic operation. The design is fabricated in a 65-nm CMOS technology. Thanks to the dynamic nature of the CDC, sampling rates from 1 S/s up to 100 kS/s are supported and capacitances from 1.23 to 24.59 pF can be digitized, while the power scales inherently from 0.1 nW to $1~\mu \text{W}$ . Optionally, the range can be further extended to >100 pF, and oversampling can be used to enhance resolution. This makes the design versatile to efficiently deal with a variety of sensors having different speed and resolution requirements and different capacitance values. The 0.1 nW lowest absolute power is $> 20\times $ smaller than the prior art, and the figure of merit (FoM) from 18 to 59 fJ/conv-step is also the lowest among prior designs. To provide application examples, this chip is further verified with a microelectromechanical (MEMS) pressure sensor and a MEMS accelerometer. It can measure environmental pressure consuming only 0.8 nW at a speed of 100 S/s, and measure acceleration using 1.4 nW at a speed of 200 S/s.

Low-Cost System of Direct Measurement of Dissipation Factor for High-Voltage Electrical Machine

Schering bridge network can be used to measure the loss angle of an insulating material of electrical machines and its winding capacitance. But, this type of bridge measurement technique suffers from error due to the effect of stray capacitances in both between the bridge output nodal points and also between bridge output nodal points and the ground. These errors can be minimized by using the Wagner earth technique. The limitation of this method is the repetition of bridge balance and Wagner earth balance that is required in every observation. In this paper, a modified Schering bridge network has been developed using operational-amplifier (op-amp) to minimize the stray capacitances. A potentiometer has been used to adjust the sensitivity of the bridge. The experiment has been performed on a 3.3-kV, 130-kW, three-phase squirrel cage induction motor in a process plant. An additional electronic measurement circuit has been incorporated to measure the dissipation factor tan $({\delta)}$ directly in terms of voltage ratio. For a particular value of the bridge sensitivity factor, the change of dissipation factor with the variation of voltage at line frequency has been observed and found satisfactory.

Design of Flow Transmitter using a Capacitive Type Sensor

Rotameter is a local indicating and variable area type flow sensor that requires a special type of transducer for the transmission of its readings to remote site. In this paper, capacitive type rotameter is designed and analysed. The bob of rotameter is connected with a thin wire while another end of that straight wire is connected with a thin rectangular shape aluminium oxide plate, which lies between parallel plate capacitors. The modified De Sauty’s Bridge has been used for measuring the variation in capacitance with respect to flow rate. The bridge output passes through voltage to current converter to achieve 4–20 mA signals.

Setup for the dynamic calibration of bridge amplifiers from DC up to 10 kHz

<p class="Abstract">Measurements of mechanical quantities are often carried out with transducers with a bridge output. The output signals are conditioned using bridge amplifiers. If dynamically changing quantities are going to be measured traceably, the bridge amplifier must be calibrated dynamically.</p>This paper describes a dynamic bridge amplifier calibration setup based on the new PTB dynamic bridge standard. The calibration is carried out by the synchronous sampling of the bridge amplifier output voltage and a reference signal provided by the calibrated dynamic bridge standard. The dynamic bridge standard enables calibrations in a frequency range from DC (static calibration) up to 10 kHz. An overview of the different measurement uncertainty contributions is given, and the first measurement results show good agreement with a previously established measurement setup.

An Energy-Efficient 3.7-nV/<inline-formula> <tex-math notation="LaTeX">$\surd$ </tex-math> </inline-formula>Hz Bridge Readout IC With a Stable Bridge Offset Compensation Scheme

This paper describes an energy-efficient bridge readout IC (ROIC), which consists of a capacitively coupled instrumentation amplifier (CCIA) that drives a continuous-time delta–sigma modulator (CT $\Delta \Sigma \text{M}$ ). By exploiting the CCIA’s ability to block dc common-mode voltages, the bridge’s bias voltage may exceed the ROIC’s supply voltage, allowing these voltages to be independently optimized. Since bridge output is typically much smaller than bridge offset, a digital to analog converter (DAC) is used to compensate this offset before amplification and thus increase the CCIA’s useful dynamic range. Bridge loading is reduced by using a dual-path positive feedback scheme to boost the CCIA’s input impedance. Furthermore, the CCIA’s output is gated to avoid digitizing its output spikes, which would otherwise limit the ROIC’s linearity and stability. The ROIC achieves an input-referred noise density of 3.7 nV/ $\surd $ Hz, a noise efficiency factor (NEF) of 5, and a power efficiency factor (PEF) of 44, which both represent the state of the art. A pressure sensing system, built with the ROIC and a differential pressure sensor (AC4010), achieves 10.1-mPa ( $1\sigma$ ) resolution in a 0.5-ms conversion time. The ROIC dissipates about 30% of the system’s power dissipation and contributes about 6% of its noise power. To reduce the sensor’s offset drift, a temperature compensation scheme based on an external reference resistor is used. After a two-point calibration, this scheme reduces bridge offset drift by $80\times $ over a 50 °C range.

Configuration of a Self-Heated Double Wheatstone Bridge for 2-D Wind Sensors

A self-heated double Wheatstone bridge configuration for a 2-D wind sensor is presented. Without a central heating element, eight thermistors are symmetrically arranged in two orthogonal directions, and four of them in each direction make up a Wheatstone bridge. The eight thermistors simultaneously act as the heating sources and temperature sensing elements. By applying the constant current supply to the bridge, the terminal voltage across the bridge and the bridge output voltage are utilized to measure the wind speed and direction, respectively. The 2-D wind sensor has been simulated numerically and fabricated directly on the ceramic substrate. Experiments demonstrate that the measured speed varies from 0 to 40 m/s with an error less than ±2 m/s while the measured direction spans from 0° to 360° with an error less than ±3° after calibration. The double bridge configuration greatly simplifies the measurement and control circuits for the 2-D wind sensor.

GENOME-WIDE ANALYSES OF REMISSION ON VENLAFAXINE TREATMENT IN OLDER ADULTS WITH LATE-LIFE DEPRESSION

We present a 34 GHz continuous wave (CW)/pulsed electron paramagnetic resonance (EPR) spectrometer capable of pulse-shaping that is based on a versatile microwave bridge design. The bridge radio frequency (RF)-in/RF-out design (500 MHz to 1 GHz input/output passband, 500 MHz instantaneous input/output bandwidth) creates a flexible platform with which to compare a variety of excitation and detection methods utilizing commercially available equipment external to the bridge. We use three sources of RF input to implement typical functions associated with CW and pulse EPR spectroscopic measurements. The bridge output is processed via high speed digitizer and an in-phase/quadrature (I/Q) demodulator for pulsed work or sent to a wideband, high dynamic range log detector for CW. Combining this bridge with additional commercial hardware and new acquisition and control electronics, we have designed and constructed an adaptable EPR spectrometer that builds upon previous work in the literature and is functionally comparable to other available systems.

Bulk-micromachined, SOI-based half-bridge silicon strain gauges for high pressure applications

This paper presents a new half-bridge silicon strain gauge fabricated on a silicon-on-insulator (SOI) substrate by MEMS bulk-micromachining technology. These gauges have holes etched through the wafer by deep reactive ion etching (DRIE) and a closed shape with four sides, unlike the current competitive devices with open structures. This unique design minimizes the shifting or rotation of gauge position and enhances the bonding strength during glass-frit bonding, leading to an improved sensor performance and yield, and hence, a reduction in sensor cost. The prototype half-bridge gauges were tested under strains ranging from −170 to 170 and were shown to have a linear output with a typical gauge factor of about 112 and an average hysteresis of 0.0192% FS. In addition, the full bridge output for 0–50 bar pressure shows a typical sensitivity of about 0.345 mV/V/bar, a maximum thermal zero shift of −7.33% FS, and a thermal sensitivity shift of −0.17% FS/°C.

Account of Temperature Change at Calibration of Air Flow Sensor

The article describes of temperature change consideration during the calibration of air flow sensor for a car engine. The sensor uses a blade made of elastic material with strain gauges applied to the front and the back surfaces, the deformation of which is measured and recalculated into a mass flow of air. They suggested the system of equations whose solution makes it possible to determine the mass flow rate and air temperature according to the known signal values at the measuring bridge output and the measuring circuit resistance. The coefficients of equation system are determined during calibration and then are recorded into the memory of the microcontroller sensor.

Precise determination of thermal parameters of a microbolometer

Determination of microbolometer thermal properties such as thermal capacitance, conductance, time constant, and IR responsivity is of the utmost importance as they directly influence microbolometer performance. Here we show a technique to measure them by using a minimized self-heating effect, thus leading to their precise determination via measurements based on an AC-biased Wheatstone bridge containing a microbolometer. The bridge outputs were subtracted from each other by a differential voltage preamplifier with its output processed by a lock-in amplifier. The lock-in amplifier output as a function of the amplitude of AC bias provided an amplitude of microbolometer thermal conductivity. A microbolometer temperature response to pulse irradiation of its membrane provided the value of its thermal time constant and, thus, its thermal capacitance. Finally, we also extracted microbolometer responsivity using a blackbody IR source. The method was experimentally verified using a micromachined bolometer, which showed excellent agreement with the analytical solution.

Characteristics of a Resonant Direct-Voltage Transducer with Phase Control by the Fundamental Harmonics Method

Approximate expressions for the calculation of the load and control characteristics of the direct-voltage transducer were obtained by the fundamental harmonics method on the basis of the linear equivalent circuit of a direct-voltage transducer constructed on the assumption of current harmonicity in the series LC circuit. Comparison of the load characteristics constructed according to the grounded exact method based on the fitting method and the obtained approximate formulas shows that the fundamental harmonic method may be used for calculation of the static characteristics at the phase regulation in the continuous current mode with acceptable practical accuracy. In the discontinuous current mode, the method gives an overestimated output voltage, with the exception of the mode close to idling, where the voltage values are underestimated. The error of the basic harmonic method increases with the decrease in the relative duration of the pulses at the output of the inverter bridge.