Full Scale Deflection Research Articles

A Simple Approach to Connecting Pt100 by Utilizing an Electroacoustic Resonance Tube

Temperature transducers are frequently employed to keep track of process variables with different kinds of industrial controllers. One of the widely used temperature sensors is Pt100. A novel approach of utilizing an electroacoustic transducer in signal conditioning for Pt100 is proposed in this paper. A "signal conditioner" is a resonance tube filled with air, which is operated in a free resonance mode. The Pt100 wires are connected to one of the leads of the speaker in the resonance tube where the temperature changes, which is related to Pt100 resistance. The resistance affects the amplitude of the standing wave that is detected by an electrolyte microphone. An algorithm for measuring the amplitude of the speaker signal is described, as well as the building and functioning of the electroacoustic resonance tube signal conditioner. The microphone signal is acquired as a voltage using LabVIEW software. A virtual instrument (VI) developed under LabVIEW provides a measure of the voltage using standard VIs. The findings of the experiments reveal a link between the measured amplitude of the standing wave within the tube and the change in Pt100 resistance as the ambient temperature changes. Additionally, the suggested method may interface with any computer system when a sound card is added to it without the need for any extra measuring tools. The maximum nonlinearity error at full-scale deflection (FSD) is estimated at roughly 3.77%, and the experimental results and a regression model are used to assess the relative inaccuracy of the developed signal conditioner. When comparing the proposed approach with well-known approaches for Pt100 signal conditioning, the proposed one has several advantages such as its simplicity of connecting Pt100 to a personal computer directly via the sound card of any personal computer. In addition, there is no need for a reference resistance to perform a temperature measurement using such a signal conditioner.

Experimental Investigation of Microcontroller-Based Acoustic Temperature Transducer Systems

Temperature transducers are commonly used to monitor process parameters that are controlled by various types of industrial controllers. The purpose of this study is to design and model a simple microcontroller-based acoustic temperature transducer based on the variations of resonance conditions in a cylindrical resonance tube. The transducer's operation is based on the generation of an acoustic standing wave in the free resonance mode of generation within a cylindrical resonance tube which is converted into a train of pulses using Schmitt trigger circuit. The frequency of the generated standing wave (i.e., the train of pulses) is measured by the Arduino Uno microcontroller, where a digital pin is used to acquire pulses that are counted using a build-in software function in an Arduino IDE environment. Experimental results are performed for three sizes of diameters to investigate the effect of the diameter of resonance tube on the obtained results. The maximum nonlinearity error according to Full-Scale Deflection (FSD) is about 2.3 percent, and the relative error of the transducer is evaluated using experimental findings and the regression model. The circuit simplicity and design of the suggested transducer, as well as the linearity of its measurements, are notable.

Bioinspired PDMS-graphene cantilever flow sensors using 3D printing and replica moulding

Flow sensors found in animals often feature soft and slender structures (e.g. fish neuromasts, insect hairs, mammalian stereociliary bundles, etc) that bend in response to the slightest flow disturbances in their surroundings and heighten the animal’s vigilance with respect to prey and/or predators. However, fabrication of bioinspired flow sensors that mimic the material properties (e.g. low elastic modulus) and geometries (e.g. high-aspect ratio (HAR) structures) of their biological counterparts remains a challenge. In this work, we develop a facile and low-cost method of fabricating HAR cantilever flow sensors inspired by the mechanotransductory flow sensing principles found in nature. The proposed workflow entails high-resolution 3D printing to fabricate the master mould, replica moulding to create HAR polydimethylsiloxane (PDMS) cantilevers (thickness = 0.5–1 mm, width = 3 mm, aspect ratio = 20) with microfluidic channel (150 μm wide × 90 μm deep) imprints, and finally graphene nanoplatelet ink drop-casting into the microfluidic channels to create a piezoresistive strain gauge near the cantilever’s fixed end. The piezoresistive flow sensors were tested in controlled airflow (0–9 m s−1) inside a wind tunnel where they displayed high sensitivities of up to 5.8 kΩ m s−1, low hysteresis (11% of full-scale deflection), and good repeatability. The sensor output showed a second order dependence on airflow velocity and agreed well with analytical and finite element model predictions. Further, the sensor was also excited inside a water tank using an oscillating dipole where it was able to sense oscillatory flow velocities as low as 16–30 μm s−1 at an excitation frequency of 15 Hz. The methods presented in this work can enable facile and rapid prototyping of flexible HAR structures that can find applications as functional biomimetic flow sensors and/or physical models which can be used to explain biological phenomena.

Criterion of stability of hydraulic cylinder and method of increasing its reliability under longitudinal-transverse loads

Currently, in most cases, the study of the operability of hydraulic cylinders in terms of their bearing capacity is carried out by means of assessing the longitudinal stability of a compressed rod with the variable cross section. In this case, the inclination of the rod in space is not taken into account. However, during operation, as a rule, a hydraulic cylinder inclined in space due to longitudinal-transverse loading is deformed in the vertical longitudinal plane with the appearance of a full-scale deflection. So, the limit value of the longitudinal compressive force is less than the limit compressive force of a stable rod, which implies that a rod having an initial curvature is more susceptible to bending, appearance of residual deformations in its elements and has less reliability than a straight, vertically arranged one. As the guide elements of the hydraulic cylinder wear out, its total deformation increases, which leads to an increase in longitudinal-transverse loads. With regard to long-stroke hydraulic cylinders, a special danger is their immediate stop in space when the working equipment of the machine meets an insurmountable obstacle. The purpose of the study is a scientifically based description of the areas of functioning of the hydraulic cylinder in the conditions of longitudinal-transverse bending or stability, as well as the boundaries separating them

A novel optical 3D force and displacement sensor – Towards instrumenting the PapillArray tactile sensor

As robots move into unstructured environments, tactile sensing will become an essential capability of any robotic gripper attempting to engage in dexterous object manipulation. Sensing the frictional properties of the sensor-object interface (along with contact forces and torques) is essential for determining the minimum grip force required to securely grasp an object; however, most existing artificial tactile sensors are incapable of sensing the property of friction. In previous work, a design was presented for a grip security sensor – the PapillArray – which consists of an array of independent silicone pillars with different uncompressed heights, inspired by the papillae in the skin of the human finger pad. It was shown that tracking the relative deflections of the pillar tips can be used to detect incipient slip; and when incipient slip is detected, measuring the 3D force on the pillar provides an estimate of the coefficient of static friction. In a continuation of this work, here we present a method of instrumenting the movement and forces experienced by the pillars of the PapillArray. A novel pinhole camera design is implemented whereby deformation of the pillar results in both movement and change in area of a spot of light, projected onto a quadrant photodiode. The four quadrant photodiode signals are mapped to true 3D displacement and force using multivariate regression. The accuracy of the mapping’s position and force estimates are validated using both video-tracking of the pillar tip and measurements made with a 3D force sensor, respectively, when stimulating the pillar with a spiral XY displacement pattern at various Z compressions. The overall displacement estimation error (mean ± SD) in the X, Y and Z axes was 0.012 ± 0.077 mm, 0.041 ± 0.074 mm and 0.010 ± 0.023 mm, respectively, for a full-scale deflection of 10.0 mm in X and Y, and 3.25 mm in Z. The overall force estimate error (mean ± SD) was 0.002 ± 0.045 N, -0.007 ± 0.049 N and 0.073 ± 0.118 N, for full-scale force of approximately 4 N in X and Y and 11 N in Z, respectively. The sensitivity of the pillar to vibration (between 100 and 1000 Hz) was also tested, as this may help to detect incipient slip events. The pillar can detect vibration up to 1000 Hz for a vibration displacement amplitude as small as 0.35 μm. This technique can be used to instrument all pillars in the PapillArray sensor, thereby facilitating incipient slip detection and friction measurement. Such a sensor would be of particular benefit in a robotic gripping application where it is important to apply only the grip force required to prevent slip of the object of interest, both to reduce the energy usage of the gripping system and to avoid damaging the gripped object.

Design, fabrication and testing of fiber bragg grating based fixed guided beam pressure sensor

A stainless steel pressure sensor using rigid center diaphragm and a fixed guided beam with FBG sensor is proposed in this paper. Two bare FBGs are bonded on to the tensile and compressive regions of the fixed guided beam. The deflection of the diaphragm due to the applied pressure induces strain on to the fixed guided beam which in-turn shifts Bragg wavelength of the FBG. The sensor is fabricated and tested for its performance in the range of 0–20 bar. The test results are in close agreement with the results obtained from analytical and experimental models. The sensitivity, nonlinearity and resolution of the sensor are found to be 0.103 nm/bar, 0.0008% full scale deflection (FSD) and 0.05 bar. The use of rigid center diaphragm improves the linearity of the sensor for a wider pressure range, and the fixed guided beam provides equal magnitudes of tensile and compressive stresses on the surface of the beam. The differential output in wavelength shifts of the two FBGs nullifies the temperature effect and hence offers temperature compensation.

Resonance based DC current sensor

The paper presents design, development and testing of a resonant proximity DC current sensor to measure current in the range of 0–20mA. The sensor is built using cantilever structure with piezoelectric excitation, sensing and closed loop electronics. The sensor measures the DC current by measuring the shift in resonance frequency of the cantilever beam. The proposed measurement system is novel, simple and accuracy is found to be 1.1% of full scale deflection.

Piezoelectric based resonant mass sensor using phase measurement

The paper presents design, development and testing of a resonant sensor to measure mass in the range of 0–12 g. The sensor is built using cantilever structure with piezoelectric excitation, sensing and microcontroller based closed loop electronics. The sensor measures the unknown mass by measuring the shift in resonance frequency of the cantilever beam. The shift in resonance frequency for a change in mass is detected by measuring the phase difference between the piezoelectric sensor output and actuator input using microcontroller. The proposed measurement system is simple and accuracy is found to be ±1.2% of full scale deflection.

Determination of serotonin, melatonin and metabolites in gastrointestinal tissue using high‐performance liquid chromatography with electrochemical detection

In this paper we show a simple isocratic chromatographic method for the detection of serotonin and its precursors and metabolites from various types of gastrointestinal tissue. The paper measures for the first time basal measurements of melatonin in the gastrointestinal tract, which has recently been shown to be released from the musosal lining of the gut. Tissue samples were stable following sample preparation in either 0.1 m perchloric acid or mobile phase. Analysis was carried out using a mobile phase consisting of 10% acetonitrile-90% acetate acid buffer pH 4.0 with 2 mm decane-sulfonic acid sodium salt at a column temperature of 50 degrees C. Electrochemical detection was utilized at a potential of +850 mV vs Ag/AgCl reference electrode at 10 microA full-scale deflection. The detection limit of 5-HT and melatonin was 241 and 308 nm respectively for a 10 microL injection. As a result of the method optimization, total analysis was reduced to 30 min. Accurate responses of the tissue samples following sample preparation could be obtained following a week after storage at -80 degrees C. This method is capable of preparing and analysing of samples from all regions of the gastrointestinal tract.

Evaluation of an ultrasonic echo-tracking method for measurements of arterial wall movements in two dimensions

The longitudinal movement of blood vessel walls has so far gained little or no attention, as it has been presumed that these movements are of a negligible magnitude. However, modern high-resolution ultrasound scanners can demonstrate that the inner layers of the arterial wall exhibit considerable movements in the longitudinal direction. This paper evaluates a new, noninvasive, echo-tracking technique, which simultaneously can track both the radial and the longitudinal movements of the arterial wall with high resolution in vivo. Initially, the method is evaluated in vitro using a specially designed ultrasound phantom, which is attached to and moved by an X-Y system, the movement of which was compared with two high-resolution triangulation lasers. The results show an inaccuracy of 2.5% full scale deflection (fsd), reproducibility of 12 microm and a resolution of 5 microm, which should be more than sufficient for in vivo studies. The ability of the method is also demonstrated in a limited in vivo study in which a preselected part of the inner vessel wall of the right common carotid artery of a healthy volunteer is tracked in two dimensions over many cardiac cycles. The results show well reproducible x-y movement loops in which the recorded radial and longitudinal movements both are of the magnitude millimetre.

Simple and rapid determination of serotonin and catecholamines in biological tissue using high-performance liquid chromatography with electrochemical detection

Using the CNS of Lymnaea stagnalis a method is described for the rapid analysis of neurotransmitters and their metabolites using high performance liquid chromatography coupled with electrochemical detection. Tissue samples were homogenised in ice-cold 0.1 M perchloric acid and centrifuged. Using a C 18 microbore column the mobile phase was maintained at a flow rate of 100 μl/min and consisted of sodium citrate buffer (pH 3.2)–acetonitrile (82.5:17.5, v/v) with 2 mM decane-sulfonic acid sodium salt. The potential was set at +750 mV versus Ag|AgCl reference electrode at a sensitivity of 50 nA full scale deflection. The detection limit for serotonin was 11.86 ng ml −1 for a 5 μl injection. Preparation of tissue samples in mobile phase reduced the response to dopamine and serotonin compared with perchloric acid. In addition it was found that the storage of tissue samples at −20 °C caused losses of dopamine and serotonin. As a result of optimising the sample preparation and mobile phase the total time of analysis was substantially reduced resulting in a sample preparation and assay time of 15–20 min.

Si-SiC ceramics from plant precursor

Synthesis of materials from naturally grown plants has recently received interest [1, 2]. Plants often possess natural composite structures and exhibit high mechanical strength, low density, high stiffness, elasticity and damage tolerance. These advantages are because of their genetically built anatomy, developed and matured during different hierarchical stages of a long-term evolutionary process. There is a possibility of producing novel silicon carbide (SiC) ceramic materials nearly isomorphous to naturally grown plants, on the macroand micro scale. SiC ceramics are commonly utilized for different structural applications. Among the various methods of producing SiC ceramics, reaction bonding/reaction sintering [3] has been shown to be the cheapest and the most commercially viable. Reaction bonding/reaction sintering is based on the C-Si reaction and is conventionally restricted to synthetic preforms [3, 4]. SiC ceramics can also be made using bio-structure derived preforms [5–7]. A wide variety of plants and plant-parts can be used for making different varieties of SiC ceramics [8–10]. Biological preforms from various soft woods, hard woods and non-wood ingredients, commonly used in pulp and paper manufacturing, can be employed for producing SiC ceramics. In view of the variations in dimensions, composition and morphology of the naturally grown plant structures, the shape and composition of the bulk SiC produced will vary significantly. The formation of SiC ceramics using monocotyledonous trees as the precursor is reported here. A monocotyledonous tree from a local source was used as the precursor plant. It was transformed to a porous skeletal carbonaceous preform of rectangular shape (of approximately 41 cm2 external surface) following a pyrolysis process at around 800 ◦C without any structural damage (cracking, loss of integrity etc.) [11]; it was subsequently reacted with silicon to yield Si/SiC ceramics under vacuum at a temperature of around 1600 ◦C [12]. After the reaction the macroscopical structural integrity was totally retained. The carbon preform and the final product were subjected to: X-ray diffraction (PW 1710, Philips, Holland); microstructural examination using light microscopy (Zetopan, Reichert, Austria) and scanning electron microscopy (SE-440, Leo-cambridge, Cambridge, U.K.); determination of the volumetric phase composition of the final ceramic by the point counting method from light photomicrographs; and thermogravimetric analysis (TGA) using a thermo-balance (STA 490C, Netzsch-Geratebau GmbH, Germany) up to 1200 ◦C in flowing air (70 ml/min) at a rate of 10 ◦C/min. Density was determined by water displacement method and porosity by the boiling water method. The threepoint bending strength and Young’s modulus of Si/SiC ceramic material were determined at room temperature using an Instron Universal Testing Machine, and the deflection was monitored through a LVDT with a resolution of 0.05% of the full scale deflection. The specimens were 45 mm × 3.5 mm × 2.5 mm in size, ground and polished to 1 μm finish. Five tests were conducted and an average value was recorded.

Calorimetric measuring systems

This paper discusses the calorimetric measuring system. The calorimetric principle is one of the most promising methods for accurate power measurements. A calorimetric wattmeter provides a useful tool for use in the developments of new, energy-efficient, electrical components for industrial and consumer products. Power measurements can be performed with an accuracy of 0.2% of full-scale deflection using the proposed calorimetric measuring method.

Induced-shear piezoelectric actuators for rotor blade trailing edge flaps

Much of the current rotorcraft research is focused on improving performance by reducing unwanted helicopter noise and vibration. One of the most promising active rotorcraft vibration control systems is an active trailing edge flap. In this paper, an induced-shear piezoelectric tube actuator is used in conjunction with a simple lever–cusp hinge amplification device to generate a useful combination of trailing edge flap deflections and hinge moments. A finite-element model of the actuator tube and trailing edge flap (including aerodynamic and inertial loading) was used to guide the design of the actuator–flap system. A full-scale induced shear tube actuator flap system was fabricated and bench top testing was conducted to validate the analysis. Hinge moments corresponding to various rotor speeds were applied to the actuator using mechanical springs. The testing demonstrated that for an applied electric field of 3 kV cm−1, the tube actuator deflected a representative full-scale 12 inch flap ±2.8° at 0 rpm and ±1.4° for a hinge moment simulating a 400 rpm condition. The per cent error between the predicted and experimental full-scale flap deflections ranged from 4% (low rpm) to 12.5% (large rpm). Increasing the electric field to 4 kV cm−1 results in ±2.5° flap deflection at a rotation speed of 400 rpm, according to the design analysis. A trade study was conducted to compare the performance of the piezoelectric tube actuator to the state of the art in trailing edge flap actuators and indicated that the induced-shear tube actuator shows promise as a trailing edge flap actuator.

Determination of polyamines as their benzoylated derivatives by HPLC.

AbstractAlmost all of the methods available to analytical biochemists have been applied to polyamine analysis at some time. The diversity of the methods used is an indication of the difficulties experienced in attempts to measure the polyamine content of biological samples. The quantitation of polyamines by high-pressure liquid chromatography (HPLC) of then benzoyl derivatives was described by Redmond and Tseng (1) in 1979 and has been modified at intervals ever since (2–12). The advantages of this technique are its relative simplicity and the need for only very basic HPLC equipment—pump, column, injection valve, and UV-detector. The main disadvantage, as noted by Seiler (13,14), is that benzoyl chloride, in addition to undergoing condensation with primary and secondary amines (Fig. 1), may also react with imidazole nitrogens and phenolic hydroxyl groups. However, benzoylation results in fewer side reactions than are seen with dansyl chloride and hence extensive clean-up procedures may not be necessary. The main contaminants in the chromatogram are benzoyl chloride, benzoic acid, benzoic anhydride, and methylbenzoate, the first two being quantitatively the most important. Contrary to the accepted dogma, some benzoyl chloride may survive the derivatization procedure and be extracted and applied to the column; its presence can be detected by a peak in the chromatogram (Fig. 2) and by its odor if the top of the column is unscrewed; use of a guard column (or cartridge) will reduce the deleterious effects benzoyl chloride on the analytical column. Benzoic anhydride may comigrate with spermine, benzoic acid can interfere with the separation of N-acetylputrescine and N-(3-aminopropyl)pyrrolidin-2-one (7), and methyl benzoate can overlap N 1-acetylspermidine, depending on the solvent mixture used. Clean-up steps have been recommended by some authors (12,15) and do result in the reduction/removal of some contaminating peaks. However, if these do not interfere then thus step can be omitted. Methanol-water is the most widely used solvent system and most reported separations have been performed isocratically (1–5,7,8,10–12), obviating the need for a gradient maker or two pump system, although use of a gradient may enable the simultaneous detection of other compounds (6,9). Acetonitrile-water mixtures, also used isocratically, can improve sensitivity (11). The characteristics of the assay have been extensively investigated (4,7,12). The reaction between benzoyl chloride and putrescine or spermidine under alkaline conditions (Schotten-Baumann condensation). Chromatogram of benzoylated polyamines. The peaks, which were identified by individual analyses, are 1, benzoic acid; 2, putrescine; 3, benzoyl chloride; 4, spermidine; 5, diaminooctane, 6, spermine. Flow rate 0.4 mL/min, detection at 229 nm, chart speed 300 mm/h, full scale deflection = 0.1 absorbance. KeywordsBenzoic AcidBenzoyl ChlorideMethyl BenzoatePolyamine ContentDansyl ChlorideThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Wind-induced deflections of freestanding lattice towers

Full-scale deflection measurements were performed on a 67 m steel frame tower and a 233 m steel truss tower under wind loading. Measurements were acquired by various means and compared with along-wind theoretical estimates. The latter were obtained using a simplified frequency domain prediction that incorporates some practical observations and remarks. The dynamic cross-wind response of lattice towers was also measured and discussed.

Multi-channel pressure sensor using speckle interferometry

The performance of two-dimensional pressure sensor arrays, consisting of 13 × 13 deformable steel diaphragms, is investigated. The pressureinduced out-of-plane component of the displacement field of all 169 sensors is measured in parallel using phase-stepping speckle interferometry. Subsequent least-squares fitting of the theoretical field provides a quantitative measure of the average pressure acting on each sensor. With monotonically-increasing load and suitable calibration, each pressure value can be measured to an accuracy of better than 1% of the full scale deflection. The current pressure range of 0–2.74 kPa can be extended by increasing the number of interferograms recorded.

Potassium-selective optrode based on an immobilized fluorogenic crown ether

A new optical sensor phase for potassium ions has been developed based on the immobilization of the pH-dependent fluorogenic crown ether 4-acryloylamidobenzo-18-crown-6 on the non-ionic polymeric resin Amberlite XAD-2. Two different optical designs, a flow-through sensor and a fibre optic probetype sensor (optrode), have been constructed and their analytical performance characteristics have been evaluated. The resulting fluorimetric sensors for K+ ions exhibited detection limits of 0.4 or 0.8 μM of K+ (16 μg/l or 31 μg/l), depending on the design, while the linear response occurred from 1 to 25 μM of the metal concentrations. The precision, evaluated as the relative standard deviation of measurements of K+ levels at around ten times the detection limit (e.g. 5 μM), turned out to be around ±2%. Advantageous features of this fluorimetric sensing phase and optrode include ease of construction, simplicity of use, reversibility, short response times (ca. 1 min full scale deflection) selectivity and operational stability, suitable for sensing potassium at low levels in complex matrices such as biological fluids. The fluorimetric optical sensor has been successfully applied to the direct determination of potassium in clinically important samples (serum and urine) and in natural waters. Very good accuracy has been obtained just using adequate synthetic aqueous potassium standards for calibration.

Monolithic silicon magnetic compass

Abstract In this report, an integrated magnetic sensor which offers the direction of the applied magnetic field is presented. This integrated sensor contains a two-dimensional magnetic detector which detects the in-plane magnetic vectors, Bx and By, and a signal conversion circuit which calculates the direction θ (=tan−1(By/Bx)) using the translinear circuit technology. This integrated magnetic sensor has not only the direction output but the output for the intensity (the absolute value) of the applied magnetic field. The test device was fabricated using the standard bipolar analog IC technology and its characteristics were examined. As a result, the direction of the applied magnetic field was obtained with maximum error of ± 2% full-scale deflection.

Determination of Methyl Bromide in Foods by Headspace Capillary Gas Chromatography with Electron Capture Detection

Methyl bromide (MB, bromomethane) is determined in a variety of foods by headspace capillary gas chromatography with electron capture detection. The comminuted food sample as an aqueous sodium sulfate slurry is equilibrated with stirring for 1 h at room temperature before a 1 mL headspace aliquot is removed and injected using a modified on-column syringe needle. Methyl bromide is cryogenically focussed at -60 degrees C and then eluted by temperature programming. The procedure requires blending of soft samples, e.g. raisins, prunes, or oranges, and ultrasonic homogenization of hard samples, e.g. wheat, cocoa beans, corn, or nuts, with portions of water and ice so the final temperature of the food-water slurry is less than 1 degree C. A 20 g aliquot (4 g food) is then added to a cold headspace vial containing 4 g sodium sulfate. Losses of MB during a 3.5 min ultrasonic homogenization of wheat were 11% at 0.95 ppb and 4.4% at 4.8 ppb. For flour, cocoa, and finely divided spices, which do not require blending, 4 g is added to the cold headspace vial containing 16 mL cold water and 4 g sodium sulfate. Studies show that comminution of wheat or peanuts must be carried out to release MB trapped within the food so the headspace equilibrium can be attained in 1 h as well as to obtain homogeneous samples and representative sampling. No interferences were noted with the above foods or with many grain-based baking mixes analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)