Minimum Displacement Research Articles

Evaluation of VLBI Observations with Sensitivity and Robustness Analyses

Very Long Baseline Interferometry (VLBI) plays an indispensable role in the realization of global terrestrial and celestial reference frames and in the determination of the full set of the Earth Orientation Parameters (EOP). The main goal of this research is to assess the quality of the VLBI observations based on the sensitivity and robustness criteria. Sensitivity is defined as the minimum displacement value that can be detected in coordinate unknowns. Robustness describes the deformation strength induced by the maximum undetectable errors with the internal reliability analysis. The location of a VLBI station and the total weights of the observations at the station are most important for the sensitivity analysis. Furthermore, the total observation number of a radio source and the quality of the observations are important for the sensitivity levels of the radio sources. According to the robustness analysis of station coordinates, the worst robustness values are caused by atmospheric delay effects with high temporal and spatial variability. During CONT14, it is determined that FORTLEZA, WESTFORD, and TSUKUB32 have robustness values changing between 0.8 and 1.3 mm, which are significantly worse in comparison to the other stations. The radio sources 0506-612, NRAO150, and 3C345 have worse sensitivity levels compared to other radio sources. It can be concluded that the sensitivity and robustness analysis are reliable measures to obtain high accuracy VLBI solutions.

Mechanical Behavior and Failure Mode of Steel-Concrete Connection Joints in a Hybrid Truss Bridge: Experimental Investigation.

The core part of a hybrid truss bridge is the connection joint which combines the concrete chord and steel truss-web members. To study the mechanical behavior and failure mode of steel–concrete connection joints in a hybrid truss bridge, static model tests were carried out on two connection joints with the scale of 1:3 under the horizontal load which was provided by a loading jack mounted on the vertical reaction wall. The specimen design, experimental setup and testing procedure were introduced. In the experiment, the displacement, strain level, concrete crack and experimental phenomena were factually recorded. Compared with the previous study results, the experimental results in this study demonstrated that the connection joints had the excellent bearing capacity and deformability. The minimum ultimate load and displacement of the two connection joints were 5200 kN and 59.01 mm, respectively. Moreover, the connection joints exhibited multiple failure modes, including the fracture of gusset plates, the slippage of high-strength bolts, the local buckling of compressive splice plates, the fracture of tensile splice plates and concrete cracking. Additionally, the strain distribution of the steel–concrete connection joints followed certain rules. It is expected that the findings from this paper may provide a reference for the design and construction of steel–concrete connection joints in hybrid truss bridges.

Computationally efficient steady‐state finite element simulation of multiphase PM AC machines

In this study the authors propose a generalised procedure for computationally efficient steady-state finite element (FE) simulation of symmetrical multiphase permanent magnet (PM) AC machines with an arbitrary number of phases. The procedure is based on newly derived general equations for phase waveform reconstruction that fully exploit the phase symmetry of multiphase electrical machines. This result can be used to reconstruct the full electrical period of any phase waveform from the smallest possible number of magnetostatic FE simulations executed within the minimum angular displacement of the rotor. Reconstruction of phase waveforms is done during post-processing and does not contribute to the execution time of FE simulations. The applicability of the proposed method is demonstrated by deriving specific equations for two-phase, three-phase, five-phase and six-phase machines. Results of classical time-stepping and newly proposed computationally efficient FE simulation are presented for four rotor PM flux switching machines with the different number of phases. Obtained results show that the relative reduction of simulation time increases with the number of machine phases.

Study of optical tag profile of the tag recognition measurement system in cultural heritage

Abstract This study exposes the process to identify the optimum optical tag profile to be used for monitoring the minimum relative displacement of two areas of the artwork. The purpose is to realize an efficient, precise, and accurate structural monitoring system with minimal invasiveness. In particular, it is designed to determine the enlargement of a crack on a fresco inside a closed environment, such as inside a church. Theoretical studies and measurements in a controlled environment are performed to identify the best mathematical distribution to be used as tags. The two small adhesive tags are the main components of the system, they are attached on the surface of the artwork and the acquisition of their images is performed through a high-resolution camera. An advanced least-squares fitting of quadratic curves and surfaces algorithms for the objective function are used to detect the relative distance between these optical tags. The appropriate parameters for monitoring potential cracks on cultural assets are determined with a fitting algorithm of an objective function. In this study, different bi-dimensional objective functions are considered to identify the best configuration.

Differential aging effects in motion perception tasks for central and peripheral vision.

The perception of motion is considered critical for performing everyday tasks, such as locomotion and driving, and relies on different levels of visual processing. However, it is unclear whether healthy aging differentially affects motion processing at specific levels of processing, or whether performance at central and peripheral spatial eccentricities is altered to the same extent. The aim of this study was to explore the effects of aging on hierarchically different components of motion processing: the minimum displacement of dots to perceive motion (Dmin), the minimum contrast and speed to determine the direction of motion, spatial surround suppression of motion, global motion coherence (translational and radial), and biological motion. We measured motion perception in both central vision and at 15° eccentricity, comparing performance in 20 older (60–79 years) and 20 younger (19–34 years) adults. Older adults had significantly elevated thresholds, relative to younger adults, for motion contrast, speed, Dmin, and biological motion. The differences between younger and older participants were of similar magnitude in central and peripheral vision, except for surround suppression of motion, which was weaker in central vision for the older group, but stronger in the periphery. Our findings demonstrate that the effects of aging are not uniform across all motion tasks. Whereas the performance of some tasks in the periphery can be predicted from the results in central vision, the effects of age on surround suppression of motion shows markedly different characteristics between central and peripheral vision.

Experimental Research on Parameters of a Late-Model Hydraulic-Electromotor Hybrid Pumping Unit

Beam pumping unit is widely applied in the oilfield area. However, the falling process of the pumping unit horsehead causes large-amplitude variations of the motor torque and greatly reduces the efficiency of the system. This paper proposes a late-model hydraulic-electromotor hybrid system which can realize energy recovery and assist electromotor work. The hybrid system can improve the matching characteristics between the electromotor and the pumping unit. A mathematical model is built and verified by experiment studies. According to the experimental and simulation results, it can be concluded that energy recovery function of the designed hydraulic-electromotor hybrid system is demonstrated to be effective, and the electromotor can keep the output power stable. As the efficiency of the hybrid power system affects the energy-saving effect, this paper establishes the efficiency model of the system and studies the key parameters affecting the efficiency of the system through experiments and simulation. The key parameters include the minimum displacement ratio of the pump and hydraulic motor, working pressure, and transmission ratio. This paper proposes a parameter optimization design method of the hydraulic-electromotor hybrid system. Under the optimal parameter combination, the hydraulic-electromotor hybrid system efficiency can reach 92%, and the electric power transmission efficiency of the system can be raised to 75%.

A two-fixed-end beam piezoelectric inertial actuator using electromagnet controlled magnetorheological fluid (MRF) for friction regulation

Friction is an important parameter to ensure the stable working of inertial actuators. It is usually regulated by adjusting the normal pressure, which will inevitably lead to wear due to the solid-to-solid contact and consequently a degradation of the output performance. This paper proposes to generate friction with magnetorheological fluid (MRF) whose shearing stress could be adjusted by the magnetic induction from an electromagnet. An inertial actuator prototype with a two fixed-end beam asymmetric structure and a MRF friction regulation unit is fabricated to verify the feasibility of electromagnet controlled MRF in friction regulation. COMSOL and MATLAB/Simulink are used for modal analysis and dynamic analysis of the proposed actuator. Experiments are conducted to evaluate the performance of the actuator. Experiment data show that the step displacement of the actuator is dramatically affected by the magnetic induction and reaches a peak value at 8.4 mT. Under the square wave excitation signal of 25 V, 7 Hz, the minimum step displacement is 0.1 μm with a rollback rate of 0.92 at a magnetic field of 19.5 mT, the maximum step displacement is 2.53 μm with a rollback rate of 0 at a magnetic field of 8.4 mT.

Instrumental platform for the static alignment of lower limb prostheses

The quality of the alignment and adjustment of lower limb prostheses is fundamental in the rehabilitation process, mainly because it contributes to preventing the prostheses from being abandoned. Prosthesis alignment is often performed subjectively based on the experience and knowledge of the healthcare professional. In this work, we present the development of a referenced static alignment equipment for lower limb prostheses. The equipment has an instrumental platform that measures important parameters for suitable alignment of lower limb prostheses, giving the therapist objective data that allow for the best adjustment and alignment of the prosthesis to the individual. The developed system has a novel procedure in the prosthesis adjustment where through a movable base. The prosthesis length can be adjusted with a smooth displacement of 0.35 mm. This minimum displacement is important because the difficulty is greater when the longitudinal adjustment required in the prosthesis is less than 10 mm. The equipment can measure the individual’s center of pressure (COP) in the anteroposterior (AP) and mediolateral (ML) directions, making it possible to adjust the knee and ankle angulation of the prosthesis, and also the alignment in the frontal plane between the healthy and the prosthetic lower limb. The measurement weight accuracy was less than 1%, while the COP measurement accuracies were found to be less than 0.4 cm in both the AP and ML directions. With a sampling frequency of 80 Hz, it is possible to carry out stabilometry analysis and use these data to improve the prosthesis adjustment procedure.

ANALYSIS OF TALL BUILDING WITH DIFFERENT LATERAL FORCE RESISTING SYSTEM

In the current circumstance, the populace is expanding rapidly, thus, the urban areas are becoming wide by devouring farming and green space and the land esteem is expanding. Another point is the tall vertical structure speaks to the country. As it builds the notoriety of the nation. To keep away from this the structures began developing vertical and thin as it arrives at a specific height the wind force governs the building as the main load more than gravity load, as the building grows higher the stability reduces. Due to a lack of design to face wind loads, as the cross-section decreases the stability reduces. And these structures are more prone to earthquakes and wind. Therefore, much research is proceeding to balance out the structure from an increasingly affordable perspective. To know the best performance and economical for the lateral force-resisting system of different types of 30 story buildings are model-led in ETABS, assuming the site location as BHUJ Gujarat, India. For the different structural systems that are compared for minimum story displacement and minimum story drift, these are the qualities that characterize the human comforts for the structure. the structural system used is conventional, shear wall, truss belt, outrigger, diagrid, and fluid viscous damper are used to compare the best performance of the structure. Above all diagrid and viscous damper shows the less displacement and drift values when compared to others but from the economic point of view viscous damper gives the best result from all the above.

Stability and dynamics of the fractured zygomaticomaxillary complex fixed using non-resorbable and resorbable 2- and 3-point miniplates, under physiological and maximal occlusal loads: a finite element analysis

Background: Given that zygoma fractures are the second most common facial trauma, knowledge of their treatments is of clinical value. Among these are fixation methods, which despite their importance are neglected in many aspects. Objectives: Therefore, for the first time in the literature, the present finite element analysis evaluated displacements and dynamics of the zygoma fixed using four 2- and 3-point resorbable and four non-resorbable plates under normal and maximal mastication loads. Methods: A maxillofacial CT scan of a man with linear fractures without severe displacements was used to model the zygoma and its adjacent bones. Seven combinations of resorbable and seven combinations of non-resorbable mini-plates 2mm thick were fixed on the zygoma (orbital rim, zygomaticomaxillary buttress [ZMB], and frontozygomatic [FZ]) using 6mm miniscrews. ZMB was fixed using an L-shaped 4-hole plate. The infraorbital rim was fixed with a curved 5-hole miniplate. The FZ suture area was fixed with a 4-hole miniplate. The model underwent 150N and 750N loads. Minimum and maximum displacements, rotational displacements, stresses, and strains of the zygoma models were calculated. Results: Non-resorbable fixation methods can yield much smaller stresses, strains, and displacements compared to resorbable fixations. Also the parameters were much smaller under the 150N load compared to the 750N load. The worst results belonged to the fixation of Rim and ZMB and the best results belonged to the fixation of ZMB-Rim, and especially FZ-ZMB, Rim-FZ, and FZ-ZMB-Rim. Conclusions: In patients with heavy masticatory forces, it is not recommended to use resorbable platesZygomatic fractures are the second most common facial injury, knowledge of their management is important. However, fixations methods, which are of importance are variable.

Диэлектрические характеристики эпоксидной смолы, модифицированной тетраэтоксисиланом, в миллиметровом диапазоне

In this work, the influence of alkoxysilanes introduced into the epoxy resin was studied. That was done in order to study the possibility of using the obtained binders in composite materials with increased radio transparency in the millimetre microwave radio band. Determination of the modified epoxy resin dielectric characteristics in the millimetre microwave radio transparency was carried out by the waveguide method. The measuring complex consisted of a precision measuring line P1-31, a tunable generator on a Gann diode (30-38 GHz), a ferrite gate, and a section of a standard-section waveguide. Based on measurements of the minimum position displacement of the standing wave coefficient by known propagation constants, the free-space wavelength λ0 for a given operating frequency, and the critical wavelength in the waveguide λcr, the loss angle tangent tg(δ) and the permittivity ε were calculated. Calculations of the permittivity ε, the angle of the dielectric loss tg(δ) and the radio transparency loss-ΔР were performed in the MathСad. Moisture absorption of samples was determined by holding them in a desiccator with a humidity of 98 %. The samples were kept in a tightly closed desiccator for 24 hours at a temperature of 25 oC. In addition, the relative moisture absorption was determined using the increase in mass. It was found that the introduction of tetraethoxysilane in the composition in an amount of 1.5-3.5% leads to a decrease in the tangent of the dielectric loss angle. The optimum is observed in the range of the modifier concentration of 2.5-3.5%. This fact confirms that at these concentrations there is a complete interaction of TEOS alkoxygroups with epoxy resin epoxygroups.

Optimization design based approach for the determination and minimization of the displacement under tensile load in hybrid composite joint

C Composite materials are most often used for lengthier and thin structures susceptible to buckle. The optimization is often carried out taking into consideration the resistance to buckling and tensile loads for minimum displacement i.e maximization of the tensile load for composite assembly joint. It well known that nowadays that composite material in structural mechanics is widely used in many industrial sectors such as in aerospace and aeronautic, automobile, marine  industries as well as in and civil engineering. Composite materials are attractive due to their advantages and performance i.e: lighter weights, high resistance to thermal and mechanical loads, resistance to corrosion and wear. In this paper an investigation is focused on the problem of hybrid assembly joint (bolted –bonded) composite structures. The aim is the optimization of the main influencing parameters. A bonded assembly has only one advantage which is its lightness; on the other hand bolted assembly has the inconvenient of increasing the weight of the structure and stress concentrators. In practice certain structural designs require the use of hybrid assembly for safety and reliability. The objective of this study is to optimize the influencing factors using both Genetic Algorithm and design of experiments for high mechanical performance of hybrid composite assembly.

Effect of TiO2 additive volume fraction in lubricant oil on the performance of hydrodynamic journal bearing

Hydrodynamic journal bearings are widely used in rotating machines where high loading condition prevails. In this work, effect of different volume fractions of TiO2 (Titanium dioxide) additive in commercially available SAE30 lubricant oil on the performance of hydrodynamic journal bearing is analysed experimentally. Hydrodynamic journal bearing test rig is used to perform the experiment. The experiment is carried out by taking different volume fractions of TiO2 additive (0.075%, 0.1% and 0.15%) in SAE30 lubricant base oil and their effect on journal bearing characteristics like coefficient of friction, pressure distribution, temperature rise, eccentricity ratio, attitude angle, minimum film thickness and displacement is analysed. Paraffin oil is used to uniformly distribute the TiO2 in the base oil and to resist sedimentation.The study shows that the addition of TiO2 additive in the base SAE30 lubricant oil is capable of significantly reducing the values of friction coefficient and maximum temperature rise. It has been found that the addition of TiO2 additive improves the performance of the hydrodynamic journal bearing. Results reveals that the additive performs better at higher loading conditions.

Fixation Methods for Mandibular Advancement and Their Effects on Temporomandibular Joint: A Finite Element Analysis Study.

Objectives Bilateral sagittal split osteotomy (BSSO) is a common surgical procedure to correct dentofacial deformities that involve the mandible. Usually bicortical bone fixation screw or miniplates with monocortical bone fixation screw were used to gain stability after BSSO. On the other hand, the use of resorbable screw materials had been reported. In this study, our aim is to determine first stress distribution values at the temporomandibular joint (TMJ) and second displacement amounts of each mandibular bone segment. Methods A three-dimensional virtual mesh model of the mandible was constructed. Then, BSSO with 9 mm advancement was simulated using the finite element model (FEM). Fixation between each mandibular segment was also virtually performed using seven different combinations of fixation materials, as follows: miniplate only (M), miniplate and a titanium bicortical bone fixation screw (H), miniplate and a resorbable bicortical bone fixation screw (HR), 3 L-shaped titanium bicortical bone fixation screws (L), 3 L-shaped resorbable bicortical bone fixation screws (LR), 3 inverted L-shaped titanium bicortical bone fixation screws (IL), and 3 inverted L-shaped resorbable bicortical bone fixation screws (ILR). Results At 9 mm advancement, the biggest stress values at the anterior area TMJ was seen at M fixation and LR fixation at posterior TMJ. The minimum stress values on anterior TMJ were seen at L fixation and M fixation at posterior TMJ. Minimum displacement was seen in IL method. It was followed by L, H, HR, M, ILR, and LR, respectively. Conclusion According to our results, bicortical screw fixation was associated with more stress on the condyle. In terms of total stress value, especially LR and ILR lead to higher amounts.

A parasitic type piezoelectric actuator with the asymmetrical trapezoid flexure mechanism

With the help of the parasitic motion of the asymmetrical trapezoid flexure mechanism, a piezoelectric actuator which could achieve linear motion with large working stroke has been presented and inspected. The structure of the asymmetrical trapezoid flexure mechanism and the motion principle of the proposed piezoelectric actuator are introduced and investigated in details. Finite Element Method (FEM) has been exploited, and an experimental system has been built up to study the working performance of the proposed piezoelectric actuator. Simulation results confirm that the parasitic motion could be achieved by the asymmetrical trapezoid flexure mechanism. Additionally, the dynamic model has been proposed for the investigation. Experimental results show that the presented actuator could obtain continuous linear motion with large working stroke by the parasitic motion of the proposed asymmetrical trapezoid flexure mechanism. The minimum stepping displacement of the proposed actuator is 0.68 μm; the maximum speed is 4676 μm/s; the output force could be as large as 91.3 g. This study shows a meaningful idea of the utilization of the asymmetrical trapezoid flexure mechanism for the design of novel piezoelectric actuators.

Dual-Active Bridge Series Resonant Electric Vehicle Charger: A Self-Tuning Method

This paper presents a new self-tuning loop for a bidirectional dual-active bridge (DAB) series resonant converter (SRC). For different loading conditions, the two active bridges can be controlled with a minimum time displacement between them to assure zero voltage switching (ZVS) and minimum circulation current conditions. The tuning loop can instantly reverse the power direction with a fast dynamics. Moreover, the tuning loop is not sensitive to series resonant tank tolerances and deviations, which makes it a robust solution for power tuning of the SRCs. For simplicity, the power is controlled based on the power-frequency control method with a fixed time displacement between the active bridges. The main design criteria of the bidirectional SRC are the time displacement, operating frequency bandwidth, and the minimum and maximum power, which are simply derived and formulated based on the self-tuning loop’s parameters. Based on the parameters of the tuning loop, a simplified power equation and power control method is proposed for DAB-SRCs. The proposed control method is simulated in static and dynamic conditions for different loadings. The analysis and simulation results show the effectiveness of the new tuning method.

Performance evaluation of outrigger location on the seismic load distribution of high-rise building structure

Various structural systems have been developed to be able to accept the lateral force of the earthquake with an optimum and economical. One of these structural systems is the outrigger system. Outrigger is one of the structural stiffening systems that can be used on building structures, especially in high-rise buildings. Structural systems such as outriggers are used for earthquake-resistant buildings, so the performance of building structures can be increased by producing minimum displacement. This research will design the building as high as 40 and 50 floors, with the calculation of earthquake based on Indonesia Earthquake Design Code SNI 1726-2012. This study will be compared the calculation of seismic loads in the building structure with and without using outrigger, so that it can be seen the difference in the seismic loads and the performance of the structure. From this research, it is found that the outrigger system can reduce the seismic loads in the structure, and also is able to reduce the lateral displacement of the structure. The inter-story lateral displacement of 50 storey and 40 storey structure can be reduce up to 2.06% and 7.84% with one outrigger and 3.76% and 12, 49% with two outrigger.

Flabby ridge management by unconfining freely flowing impression material

Completely edentulous patients often present with a severely resorbed mandibular residual alveolar ridge. Not all patients can be managed surgically therefore a prosthodontist must look for innovative techniques which fulfill the basic principles of managing such cases. There are times when upon the patient's arrival, the practitioner finds that the tray designed by the laboratory technician does not fulfill his requirements. We present a technique of recording flabby ridge if and when the special tray designed does not fulfill the criteria for recording such situation. The technique is based on the principle of non confinement of impression material in the area of flabby tissue to record tissue with minimum displacement.

Locomotion analysis of a clamper-based capsule robot in a compliant tube

A clamper-based capsule robot (CCR) capable of exploring a compliant tube is promising for a minimally invasive medical application. It is composed of a locomotion unit and some functional modules (e.g., camera and telemetry circuit) at both ends; and the locomotion unit consists of a linear mechanism, a fixed clamper, and a free clamper that can be linearly moved by the linear mechanism. For the CCR design and optimization, analyzing the interaction between the CCR and the compliant tube is necessary. For this reason, this article conducts a quantitative locomotion analysis of the CCR in the compliant tube. Based on a minimum displacement assumption and by analyzing the tube deformation induced by each CCR locomotion gait, a model correlating the CCR locomotion efficiency with it design parameters was built. Then, the correctness of the model was validated in an intestine-constructed compliant tube. With the validated model, the influence of the design parameters on the CCR locomotion efficiency was analyzed to derive the design rules. In addition, a quantitative comparison between the locomotion efficiencies of the CCR and a previously developed inchworm-like capsule robot was conducted, showing that the CCR can enable a more efficient exploration for the compliant tube.

Pressure effect on the adiabatic potential in the crystals with D<sup>2</sup><sub>3d</sub> space symmetry and strong electron-phonon interaction

Purpose. The CuInP2S6 and CuInP2Se6 crystals are characterized by an order-disorder phase transition mechanism, which is caused by electron-phonon interaction and the Jan-Teller cooperative effect. Vibronic instability is related to the electronic configuration of copper d10 in octahedral symmetry, and the disorder in the paraelectric phases can be explained by the jumping movements of Cu ions. It is of interest to study the conditions of this instability at the pressure. The main aim of our paper is to carry out the investigation of the matrix of the vibronic potential energy and the adiabatic potentials at the pressure. Methods. Adiabatic potentials concept based on the group -theoretical analysis and Pikus’ method of invariants. Results. For the case of hydrostatic pressure for crystals with D3 d symmetry, an adiabatic potential depending on the components of the strain tensor and the coordinates of normal vibrations active in the Jahn-Teller effect has been obtained. We carried out the numerical simulations of the pressure effect on the shape of the adiabatic potentials From our qualitative analysis follows that the changing of the adiabatic potential depth ( EJT ) and the value of the minimum displacement ρ 0 takes place. Especially the shape of the adiabatic potential energy is changed at the shift strain exy . Conclusions. Using the symmetry methods, we constructed the matrix of the vibronic potential energy and found the adiabatic potentials. It is shown that in a consequence of the phase transition the splitting of the equivalent minima (disorder) of the adiabatic potential on the group of the nonequivalent minima (order) is occurred. The shape of these adiabatic potentials shows that in their concept one can confirm about the order-disorder phase transition and also to consider the pressure influence on these potentials.