Linear Displacement Transducer Research Articles

Enhancing poplar-wood properties through nano-silica fortified polyvinyl-acetate impregnation

ABSTRACT The effects of pressure impregnation of nano-SiO2 fortified polyvinyl acetate (PVAc) in plantation-grown poplar-wood (Populus deltoides) on a few important physical properties, such as density, water absorption, swelling (tangential and volumetric) and surface hardness, were evaluated. Real-time tangential swelling, swelling rates and anti-swelling efficiency of the nano-wood composites were also determined using a customized linear voltage displacement transducer (LVDT)-based swell-o-meter. The dynamic light scattering technique was used to evaluate the dispersion stability and average particle size of the nano-SiO2 fortified polyvinyl acetate before impregnating in wood. The changes in the microstructure, crystallinity, and chemical interactions of nanoparticles, resin and wood elements that occurred in nano-wood composites were studied using scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy techniques. Wood impregnated with 3% nano-SiO2 fortified 20% polyvinyl acetate exhibited the lowest tangential swelling after 2 h of water immersion, while the highest anti-swelling efficiency after saturation was achieved with 3% nano-SiO2 fortified 15% polyvinyl acetate. Mechanical test results also indicated improvement in the end- and side-surface hardness of the wood impregnated with 3–5% nano-SiO2-fortified 20% PVAc. This study provides valuable insights into the potential of using fast-grown low-density poplar-wood impregnated with nano-SiO2 fortified PVAc for various value-added interior applications.

К вопросу использования в образовательном процессе разработанного программного обеспечения для исследования акустических трактов магнитострикционных преобразователей перемещений

The article is devoted to the research of the processes arising during the formation, translation and reading of information signals in the acoustic paths of magnetostrictive linear and angular displacement transducers. Mathematical models are given that make it possible to calculate the magnetic fields of annular permanent magnets and those formed by current pulses when they flow in a waveguide medium. To calculate the magnetization of the waveguide, a numerical method was developed that allows taking into account the magnetization of the waveguide material at a previous time. Mathematical models are also given to calculate the parameters of the magnetic flux of the solenoid and the output signal. Mathematical models for calculating permanent magnet magnetic fields, the developed numerical method and mathematical models for the formation of magnetic flux and output signal were implemented in the developed software used in the educational process. The research results, as well as refined and developed methods for calculating magnetic fields and the numerical method can be used to study magnetostrictive devices both at the stage of their design and operation, which reduces their final cost. It should also be noted that the article does not address issues related to the processing of the output signal, which provides opportunities for further research and further modification of the software.

Meniscal Extrusion Measurements After Posterior Medial Meniscus Root Tears: A Systematic Review and Meta-analysis

Background: Meniscal extrusion has become increasingly utilized when evaluating meniscus root abnormalities. However, no consensus definition or approach exists on how to measure extrusion. Purpose/Hypothesis: The purpose of this study was to evaluate the extent of heterogeneity in meniscal extrusion measurement techniques and reported extrusion values in knees with posterior medial meniscus root tears (PMMRTs). We hypothesized that meniscal extrusion measurement techniques would vary considerably throughout reported studies, with resultant wide-ranging published extrusion values. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The inclusion criteria consisted of all clinical and cadaveric studies reporting on meniscal extrusion after PMMRTs, excluding studies lacking data in full extension, those presenting only semiquantitative analyses, articles reporting only differences in meniscal extrusion, and review articles. Results: A total of 45 studies were included. Imaging modality types included magnetic resonance imaging (89%), 3-dimensional reconstruction with computed tomography (7%), linear displacement transducers (2%), and a combination of magnetic resonance imaging and ultrasound (2%). The 3 most commonly used landmarks to acquire coronal images for meniscal extrusion measurements were the medial collateral ligament (38%), the midpoint of the anterior-posterior length of the medial meniscus (23%), and the middle of the medial femoral condyle (19%). The pooled mean extrusion values according to the measurement location were 3.5 ± 0.7 mm, 3.9 ± 0.8 mm, and 4.5 ± 2.1 mm, respectively, with no significant differences noted between the modality types (P = .23). The pooled mean meniscal extrusion from all included studies was 3.2 ± 2.0 mm. Conclusion: Substantial variation exists in measurement techniques for meniscal extrusion, particularly as it relates to the coronal cross-sectional reference location. Further studies should aim to provide clear descriptions of the measurement method and have uniform measurement methodology to allow comparisons and pooling between studies.

Experimental testing of residual strain and displacement development in pretensioned BFRP reinforced concrete beams

The utilisation of fibre reinforced polymers (FRPs) as reinforcement for concrete elements has attracted attention mainly due to their high tensile strength, light weight and corrosion resistance. Lately, there has been an interest in basalt FRPs as a more economically competitive and environmentally friendly option. Basalt FRP is manufactured from a widely available volcanic rock in a process which does not require any additives, giving it an edge over the currently more popular glass-fibre reinforced plastic (GFRP) reinforcement. Pretensioning of FRP reinforcement with low longitudinal modulus of elasticity, such as GFRP and BFRP has been proposed as an effective solution to the concerns regarding the serviceability performance of flexural elements reinforced with these composite materials. In previous research it has been demonstrated that prestressing even at low levels can significantly reduce deflections and postpone cracking of BFRP reinforced concrete elements. This research presents an experimental investigation of pretensioned BFRP reinforced concrete tested under quasi-static loading and unloading cycles at 5kN load increments until failure. A comparison with an unprestressed sample is also provided to examine the effectiveness of prestressing at improving the structural performance of the beams. The samples were equipped with internal strain gauges and linear displacement transducers to monitor the development of strains in the reinforcement, deflections and concrete surface strains during testing. Close monitoring of the anchorage zone and the development of cracks was also conducted. Based on the experimental results it can be concluded that the prestressing of BFRP reinforced beams delays the development of residual strains and residual displacements upon unloading. Furthermore, the increase in the prestress level further reduced the residual strain and displacements.

Оdrеđivаnjе brzinе struјаnjа vаzduhа u prаvоugаоnоm zаtvоrеnоm cevovodu korišćenjem metoda polja brzina

In the technical practice, it is often necessary to measure or control the fluid flow rate in pipelines and channels. The velocity-area method requires a number of meters located at specified points in a suitable cross-section of closed conduits. Simultaneous measurements of local mean velocity with the meters are integrated over the gauging section to provide the discharge. In this paper, three approaches of this method are applied on a rectangular closed conduit to determine the air flow rate with integration techniques used to compute the discharge assume velocity distributions that closely approximate known laws, especially in the neighborhood of solid boundaries. For this purpose, meters for velocity were 7 Pitot tubes placed vertically in predefined measurement points covering the conduit height, and moved horizontally along the conduit width. The position of the Pitot tubes along the conduit width was monitored and controlled by a linear displacement transducer. Pressure is measured using digital sensors. The first technique for determination of air flow rate is on basis of fixed (stopping) measuring points across the conduit width as averaged values of local velocity, the second one is semi continual measurement of velocity profile by applying interpolation between the average local velocity on fixed (stopping) points and measured velocity in the movement between two positions, and the third is by continuously moving the Pitot tubes without stopping. The results of the three techniques are calculated and presented using different types of software. Considering the last technique, comparison of results is made applying different movement speeds of the Pitot tubes in order to examine their influence on the velocity profile.

Using an Automated Complex Micron to Determine Measurement Error of Microwave Radio Interferometers

This article presents the technique of radio interferometry measurements and a theoretical estimate of the measuring error of the reflecting surface displacement. The displacements are measured using microwave radio interferometers. This article describes the automated complex Micron design as well as its operating principle. The complex is designed to experimentally determine the error in measuring the reflecting surface displacement as well as to conduct primary and periodic verification of microwave radio interferometers. The complex Micron comprises a measuring tool of the precision class 3, that is, an incremental linear displacement transducer LIR-7A, which measures the reflecting surface displacement of the test object. Verification of the longitudinal displacement measuring line is provided for the complex Micron so that the LIR-7A transducer can be verified without dismantling it. Parallel slip gauges or similar standards can be used as the initial standard for verification. The measured displacement values, determined during verification and obtained through an alternative method providing the required accuracy of radio interferometry measurements, were compared.

Analytical and experimental study of shape memory alloy reinforcement on the performance of butt-fusion welded joints in high-density polyethylene pipe

In this article, a shape memory alloy wire is employed as confinement to enhance the flexural rigidity of the butt-fusion welded joints in the high-density polyethylene pipes. To this end, analytical and experimental studies are considered, when the shape memory alloy wire is wrapped around a butt-fusion joint and an internal pressure is applied to the high-density polyethylene pipe. To investigate the efficiency of shape memory alloy wire jacket on the performance of butt-fusion welded joint in high-density polyethylene pipe, two cases of perfect butt-fusion joint and imperfect butt-fusion joint are tested. The influence of the number of shape memory alloy wire jacket on the high-density polyethylene pipe joints as well as the effect of different flexural rigidities of the wire and high-density polyethylene pipe, and different diameters are evaluated. The deformation is measured using linear voltage displacement transducer and digital image correlation analysis at different location of the pipe length. In addition, radial strain of the pipes due to bulging is measured by electronic resistance strain gauges. Results show that the shape memory alloy wire jacket has a significant effect (33%) on enhancing imperfect butt-fusion welded joint of high-density polyethylene pipes.

Length-change patterns of the medial collateral ligament and posterior oblique ligament in relation to their function and surgery

PurposeTo define the length-change patterns of the superficial medial collateral ligament (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL) across knee flexion and with applied anterior and rotational loads, and to relate these findings to their functions in knee stability and to surgical repair or reconstruction.MethodsTen cadaveric knees were mounted in a kinematics rig with loaded quadriceps, ITB, and hamstrings. Length changes of the anterior and posterior fibres of the sMCL, dMCL, and POL were recorded from 0° to 100° flexion by use of a linear displacement transducer and normalised to lengths at 0° flexion. Measurements were repeated with no external load, 90 N anterior draw force, and 5 Nm internal and 5 Nm external rotation torque applied.ResultsThe anterior sMCL lengthened with flexion (p < 0.01) and further lengthened by external rotation (p < 0.001). The posterior sMCL slackened with flexion (p < 0.001), but was lengthened by internal rotation (p < 0.05). External rotation lengthened the anterior dMCL fibres by 10% throughout flexion (p < 0.001). sMCL release allowed the dMCL to become taut with valgus rotation (p < 0.001). The anterior and posterior POL fibres slackened with flexion (p < 0.001), but were elongated by internal rotation (p < 0.001).ConclusionThe structures of the medial ligament complex react differently to knee flexion and applied loads. Structures attaching posterior to the medial epicondyle are taut in extension, whereas the anterior sMCL, attaching anterior to the epicondyle, is tensioned during flexion. The anterior dMCL is elongated by external rotation. These data offer the basis for MCL repair and reconstruction techniques regarding graft positioning and tensioning.

Automated complex “Miсron” for determining measurement error of microwave radio interferometers

The technique of radiointeroferometric measurements is presented and a theoretical estimate of the measuring error the reflecting surface movement is given. The movement are measured with microwave radio interferometers. The automated complex “Miсron” design and principle of operation are described. The complex is intended for experimental determination of the error in measuring the movement of a reflecting surface, as well as for primary and periodic verification of microwave radio interferometers. The complex “Miсron” includes a measuring instrument of the 3rd accuracy class – an incremental linear displacement transducer LIR-7A, which measures the reflecting surface movement of the test object. For the “Miсron” complex verification of the longitudinal movement measuring line is provided, which makes it possible to verify the LIR-7A transducer without dismantling it. Planeparallel gauge blocks or similar standards can be used as the initial standard for verification. The comparison of the movement measured values determined during verification and obtained by an alternative method providing the required accuracy of radio interferometric measurements is carried out.

Differential movement of the sciatic nerve and hamstrings during the straight leg raise with ankle dorsiflexion: Implications for diagnosis of neural aspect to hamstring disorders

IntroductionIn hamstrings injuries, sciatic nerve and muscle disorders can coexist. Therefore, differential diagnosis to include or exclude nerve involvement is an important aspect of evaluation. The objective of this paper is to investigate the mechanical behaviour of the sciatic nerve and biceps femoris muscle in the proximal thigh with the ankle dorsiflexion manoeuvre at different degrees of hip flexion during the straight leg raise in cadavers. Material and methodsA cross-sectional study was carried out. Linear displacement transducers were inserted into the sciatic nerve and the biceps femoris muscle of 11 lower extremities from 6 fresh cadavers to measure potential strain of both structures during ankle dorsiflexion at 0°, 30°, 60° and 90° of hip flexion during the straight leg raise. Excursion was also measured with a digital calliper. ResultsAnkle dorsiflexion resulted in significant strain and distal excursion of the sciatic nerve at all ranges of hip flexion during the straight leg raise (p < 0.05). In contrast, the ankle movement did not affect the strain in biceps femoris at any position of the hip (p > 0.05). ConclusionAnkle dorsiflexion at different degrees of hip flexion during the straight leg raise produces changes in the strain and excursion of the sciatic nerve in the upper thigh. In contrast, the biceps femoris muscle at the same location was not affected by ankle movement. These findings show differential behaviour between the nerve and muscle with ankle dorsiflexion at this location that could be used as differential diagnosis in posterior hip pain.

Research of the displacement transducer based on ferromagnetic shape memory alloy

The use of the ferromagnetic shape memory alloy as measuring transducers and actuators is a promising direction of development of positioning systems. However, the theoretical and experimental basis for designing such systems is not sufficiently developed. The article evaluates the possibility of using the ferromagnetic shape memory alloy as a linear-displacement transducer. The influence of various types of deformation of the active element from ferromagnetic shape memory alloy and temperature on the change in its inductance is investigated. The results of full-scale and model experiments are presented. Using the dependence of the deformation on the magnetic state element makes it possible to avoid the using of special displacement transducer and thereby simplify the positioning systems. However, it is necessary to provide for measures to reduce the effect of temperature on the measurement results to improve the positioning accuracy.

Laboratory testing for evaluation of the influence of a small degree of internal erosion on deformation and stiffness

Suffusion is a type of internal erosion, namely, the transportation of soil driven by the seepage force of finer fractions within coarser fractions. The present work uses triaxial confining compression tests to study how a small degree of suffusion affects soil stiffness and deformation. This approach allows the suffusion inside a specimen to impose a downward seepage flow. Although a small degree of suffusion is not detectable, it can lead to the deterioration of earth structures. Linear displacement transducers and clip gages were attached to specimens to accurately measure the localized strain rates. In addition, the turbidity of the discharged water was evaluated. Following the downward seepage, each drained specimen was monotonically compressed. The experimental results show that cohesive soil undergoes suffusion and that most of the clay fractions bonding the sand particles erode. At intermediate strain, the deviator stress decreases in proportion to the degree of suffusion, but this decrease ceases at the critical state. Anisotropic behavior is observed and is tentatively attributed to the disruption of the soil texture, which is qualitatively monitored by scanning electron microscopy. Finally, a simple formula is proposed for evaluating the decrease in stiffness due to suffusion.

Modeling and Calibration of the Orthogonality Deviation between the "X" and "Y" Axes of Coordinate Measuring Machines

The increase of the quality in a productive process allows reduction of costs besides adding value to the product. When manufacturing a product within the tolerances specified in the design it is possible to obtain a correct operation of this product, ensuring the minimum time of use and with a lower risk of early failure. In this sense, machines and equipments involved in the manufacturing and inspection processes must also maintain an acceptable quality of operation by knowing the errors present in the machine structure through the calibration, such as errors due to lack of orthogonality between the axes, caused by inaccurate assemblies. The calibration errors in these machines allow elaborate error compensation plans and thus improve the rate of flawless products in production. The objective of this paper was to identify the influence of errors due to a lack of orthogonality in a bridge type coordinate measuring machine (CMM) through calibration and mathematical modeling of errors. Error calibration is performed with a linear displacement transducer, a granite square and a set support brackets for the granite square. By means of the calibration data and the mathematical modeling of the orthogonality deviation an influence of the measured deviation on the "X" and "Y" directions of the CMM is obtained. The error due to the lack of orthogonality between the "X" and "Y" axes of the CMM was approximately 8.9558 negative arcoseg; in this way, it is evidenced that the angle formed between these axes is 89.9975°. Through this study it can be concluded that orthogonality deviation in the main plane of the machine produces negative components for the axes "X" and "Y", with higher influence on the points collected as it away from machine scales, making greater the error intensity on the results of measurements made at positions farthest from the "X" and "Y" scales.

Investigation of Glass Transition Temperature of Asphalt Concrete

Abstract The presented manuscript identifies the mix design parameters important for the glass transition temperature and thermo-volumetric properties of asphalt–concrete mixes. A number of compacted specimens were prepared at different air-void content, by mixing different composition of materials in terms of aggregate origins, asphalt types, and gradations. The compacted mixes were later sized to required dimensions and were subjected to a uniform rate of cooling in a specially designed testing machine. The contraction of the sample during the cooling was measured by linear vertical displacement transducers, and the recorded values obtained were converted into longitudinal strain. All variables investigated in the study were found statistically significant to impact the glass transition temperature of asphalt paving mixes. The methodology adopted in this study provides a new approach to predict glass transition temperatures in asphalt–concrete mixes and identifies the mix parameters that will be helpful in delaying the glass transition temperature of the mix for reliable performance of asphaltic pavements in cold regions.

ИСПОЛЬЗОВАНИЕ ДИНАМИЧЕСКИХ ХАРАКТЕРИСТИК ДВИГАТЕЛЯ И ТУРБОКОМПРЕССОРА ДЛЯ ДИАГНОСТИРОВАНИЯ СИСТЕМ ГАЗОТУРБИННОГО НАДДУВА

The purpose of the research is to identify the peculiarities of interconnection of dynamic characteristics of the turbocharger TKR 6.1 and the engine D-245-35 in the presence of a fault in the pressurization system. In the practice of fault finding in the system of supercharging of automotive engine widely used method of diagnosis, OS-nated steak subs on the measurement of the boost pressure in the nominal modes. In terms of the service companies due to the lack of brake stands to estimate the load mode is often not possible. For acceleration of the turbocharger and engine at the department of mobile power tools, national research of Mordovsky State University named after N. P. Ogarev created diagnostic complex consisting of forming unit of the source signals, the optical sensor shaft speed of the turbocharger, sensor of frequency of rotation of the motor shaft, the linear displacement transducer arm balancing machines, analog-to-digital Converter, software and a personal computer. The tests were carried out on the engine MMZ D-245-35, with an installed turbocharger TKR-6.1, simulation of the working regimes was carried out on the roller-brake stand. The test results obtained a series of characteristics of the acceleration of the turbocharger engine D-245-35 and TKR-6.1 with a step input exposure. Analysis of the data showed that the presence of a malfunction of the boost «leak turbine inlet», «air filter clogged» leads to an increase in the transient time and reducing the frequency of rotation of the rotor TKR in all modes. Spaced- out characteristic obtained in idling mode in the fault conditions «loss of gases after the compressor» is accompanied by the growth of the amplitude value of the shaft speed TCR and the reduction of time of transition. This feature of the waveform of the acceleration allows us to identify faults of this kind in the diagnosis of the supercharging system.

Experimental Study for Structural Behaviour of Precast Lightweight Panel (PLP) Under Flexural Load

Precast lightweight concrete slab is first fabricated in workshop or industrial before construction and then transported to site and installed by skilled labour. It can reduce construction time by minimizing user delay and time for cast-in-situ to increase workability and efficiency. is environmental friendly and helps in resource reduction. Although the foamed concrete has low compressive strength compared to normal weight concrete but it has excellent thermal insulation and sound absorption. It is environmental friendly and helps in resource reduction. To determine the material properties of foamed concrete, nine cubes and six cylindrical specimens were fabricated and the results were recorded. In this study, structural behaviour of precast lightweight panel (PLP) with dry density of 1800 kg/m3 was tested under flexural load. The results were recorded and analysed in terms of ultimate load, crack pattern, load-deflection profiles and strain distribution. Linear Voltage Displacement Transducers (LVDT) and strain gauges were used to determine the deflection and strain distribution of PLP. The theoretical and experimental ultimate load of PLP was analysed and recorded to be 70 and 62 kN respectively, having a difference of 12.9%. Based on the results, it can be observed that PLP can resist the adequate loading. Thus, it can be used in precast industry for construction purposes.

Measuring nonlinear oscillations using a very accurate and low-cost linear optical position transducer

An accurate linear optical displacement transducer of about 0.2 mm resolution over a range of ∼40 mm is presented. This device consists of a stack of thin cellulose acetate strips, each strip longitudinally slid ∼0.5 mm over the precedent one so that one end of the stack becomes a stepped wedge of constant step. A narrowed light beam from a white LED orthogonally incident crosses the wedge at a known point, the transmitted intensity being detected with a phototransistor whose emitter is connected to a diode. We present the interesting analytical proof that the voltage across the diode is linearly dependent upon the ordinate of the point where the light beam falls on the wedge, as well as the experimental validation of such a theoretical proof. Applications to nonlinear oscillations are then presented—including the interesting case of a body moving under dry friction, and the more advanced case of an oscillator in a quartic energy potential—whose time-varying positions were accurately measured with our transducer. Our sensing device can resolve the dynamics of an object attached to it with great accuracy and precision at a cost considerably less than that of a linear neutral density wedge. The technique used to assemble the wedge of acetate strips is described.

Hydromechanical constraints on piping failure of landslide dams: an experimental investigation

Understanding the internal structure and material properties of landslide dams is essential for evaluating their potential failure mechanisms, especially by seepage and piping. Recent research has shown that the behaviour of landslide dams depends on the internal composition of the impoundment. We here present an experimental investigation of the hydromechanical constraints of landslide dam failure by piping. Experiments were conducted in a 2 m × 0.45 × 0.45 m flume, with a flume bed slope of 5°. Uniform dams of height 0.25 m were built with either mixed or homogeneous silica sands. Uniform-sized pebbles encased in a plastic mesh were used to initiate internal erosion. Two laser displacement sensors were used to monitor the behaviour of the dams during the internal erosion process while a linear displacement transducer and a water-level probe were deployed to monitor the onset of internal erosion and the hydrological trend of the upstream lake. Five major phases of the breach evolution process were observed: pipe evolution, pipe enlargement, crest settlement, hydraulic fracturing and progressive sloughing. Two major failure modes were observed: seepage and piping-induced collapse. Majority of the dams composed of homogeneous material failed by seepage and downstream slope saturation, whereas dams built with mixed material failed by piping. We found that an increase in soil density and homogeneity of the dam materials reduced the potential to form a continuous piping hole through the dams. Furthermore, the potential for piping and progression of the piping hole through the dams increased with an increase in the percentage of fines and a decrease in hydraulic conductivity. The rate of pipe enlargement is related to the erodibility of the soil, which itself is inversely proportional to the soil density. This study provides new insights into the governing conditions and breach evolution mechanisms of landslide dams, as triggered by seepage and piping.

The Use of Error-Correcting Codes in Displacement Transducers with Combinatorial Scales

We pose and solve the problem of using linear cyclic error-correcting codes in angular and linear displacement transducers with combinatorial code scales. It is shown that the formation of error-correcting codes can only be achieved by introducing redundancy in the number of reader elements without additional code tracks.

Experimental Study on Bond Behavior of FRP-Concrete Interface in Hygrothermal Environment

As the technique of fiber-reinforced polymer (FRP) composite material strengthened reinforced concrete structures is widely used in the field of civil engineering, durability of the strengthened structures has attracted more attention in recent years. Hygrothermal environment has an adverse effect on the bond behavior of the interface between FRP and concrete. This paper focuses on the bond durability of carbon fiber laminate- (CFL-) concrete interface in hygrothermal condition which simulates the climate characteristic in South China. Twenty 100 mm × 100 mm × 720 mm specimens were divided into 6 groups based on different temperature and humidity. After pretreatment in hygrothermal environment, the specimens were tested using double shear method. Strain gauges bonded along the CFL surface and linear variation displacement transducers (LVDTs) were used to measure longitudinal strains and slip of the interface. Failure mode, ultimate capacity, load-deflection relationship, and relative slip were analyzed. The bond behavior of FRP-concrete interface under hygrothermal environment was studied. Results show that the ultimate bearing capacity of the interface reduced after exposure to hygrothermal environments. The decreasing ranges were up to 27.9% after exposure at high temperature and humidity (60°C, 95% RH). The maximum strains (εmax) of the specimens pretreated decreased obviously which indicated decay of the bond behavior after exposure to the hygrothermal environment.