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In this study, temperatures of samples welded by 3 different welding sorting has been measured and displacements occurring on the part after wielding have been determined and an experimental comparison has been made in this regard. The welded part belongs to the front loader used in tractors. Material of the model is S355j2+N. In the experimental study, 3 samples have been welded for each process. In Process 1, welding lines have been observed outside to inside, in Process 2 inside to outside, and in Process 3 from right to left. For all parts, welding parameters and welding speed have been fixed. Welding manufacture and cooling processes have lasted 3000 seconds in total. 4 points have been determined in order to measure the temperature of the part during the experiment. For determination of displacement amount, sample parts have been measured by means of 3-dimensional laser measuring device before and after welding. When results of experiment are examined, it has been observed that temperatures curves are similar in processes no. 1 and 3; and the process has been completed by lower temperature in process no. 2. The highest temperatures measured in processes 1, 2 and 3 are respectively as 380°C, 272°C ve 310°C. Displacements of circular and cylindric points are respectively as 2.17 mm, 1.22 mm, 2.12mm. Maximum displacements of the surfaces are as 0.40 mm, 0.41 mm, 0.80 mm for process 1; as 0.10 mm, 0.28 mm, 0.83 mm for process 2; and as 0.71 mm 0.77 mm 1.39 mm for process 2. It has been concluded that process no. 2 has lower temperatures and less displacements. Less amount of displacement or distortion provides use of parts without applying correction afterwards, and eliminates surplus workmanship and time loss. [ABSTRACT FROM AUTHOR]

Hardware impairments in general and amplifier nonlinearity in particular severely limit the performance of communication links. This paper analytically provides statistical results on how a nonlinear amplifier affects the quality of signals in communication systems. In particular, we propose a statistical model that describes the nonlinear distortion as a function of the input signal’s average and instantaneous power and captures the pulse-shaping and matched filters’ effects. We show through simulations and complementary measurements that the proposed model can provide an authentic connection between the communication system parameters, power amplifier nonlinearity characteristics, and the communication system performance. It serves not only as a reliable model for nonlinear distortion analysis but also as a design tool that allows optimization of signal and filter characteristics with respect to nonlinear distortion. [ABSTRACT FROM AUTHOR]

A new technique to calculate an equivalent indirect hysteresis loop, $B_{\mathrm{ ec}}$ – $H$ loop, from the distortion of the voltage measured in the magnetic excitation coil is proposed. The aim is to facilitate the industrial implementation of magnetic characterization reducing hardware and error sources of the measuring system, as pick-up coils and their conditioning stages are not necessary. With the $B_{\mathrm{ ec}}$ – $H$ technique, the characterization of two sets of materials with very different properties using a simplified electromagnetic system has been achieved. Specifically, the change in the microstructure of annealed low-carbon steel samples was monitored and the hardness of ultrahigh steel sheets was characterized. Moreover, the conventional hysteresis cycles and $B_{\mathrm{ ec}}$ – $H$ loops are compared, and the obtained lineal relationships between the parameters derived from conventional hysteresis and $B_{\mathrm{ ec}}$ – $H$ loops verify that the $B_{\mathrm{ ec}}$ – $H$ loops can provide equivalent parameters for magnetic characterization of steel samples as conventional hysteresis loops. [ABSTRACT FROM AUTHOR]

This paper employs a high resolution quantization framework to study the effects of finite-rate quantization of the channel state information (CSI) on the performance of MISO systems over correlated fading channels. The contributions of this paper are twofold. First, as an application of the general distortion analysis, tight lower bounds on the capacity loss of correlated MISO systems due to the finite-rate channel quantization are provided. Closed-form expressions for the capacity loss in high-signal-to-noise ratio (SNR) and low-SNR regimes are also provided, and their analysis reveals that the capacity loss of correlated MISO channels is related to that of i.i.d. fading channels by a simple multiplicative factor which is given by the ratio of the geometric mean, to the arithmetic mean of the eigenvalues of the channel covariance matrix. Second, this paper extends the general asymptotic distortion analysis to the important practical problem of suboptimal quantizers resulting from mismatches in the distortion functions, source statistics, and quantization criteria. As a specific application, two types of mismatched MISO CSI quantizers are investigated: quantizers whose codebooks are designed with minimum mean square error (MMSE) criterion but the distortion measure is the ergodic capacity loss (i.e., mismatched design criterion), and quantizers with codebook designed with a mismatched channel covariance matrix (i.e., mismatched statistics). Bounds on the channel capacity loss of the mismatched codebooks are provided and compared to that of the optimal quantizers. Finally, numerical and simulation results are presented and they confirm the tightness of theoretical distortion bounds.

The dynamic range of a radio-over-fiber (RoF) link is fundamentally limited by the linearity of electro-optic modulators. Silicon photonic (SiP) processes offer significant potential for integration, but the plasma dispersion effect impacts the realizable spur-free dynamic range (SFDR). This article analyzes the underlying source of nonlinearity in SiP Mach–Zehnder modulator (MZM) and demonstrates fundamental limitations on intermodulation distortion. A SiGe low-noise distributed driver is co-designed for the SiP MZM to linearize and extend the bandwidth over which the SFDR remains high. The RoF transmitter achieves 1–20 GHz bandwidth and an SFDR of 109 dB $\cdot $ Hz2/3 at 11 GHz. To the best of our knowledge, this is the highest SFDR demonstrated for a SiP technology without incorporating predistortion. [ABSTRACT FROM AUTHOR]

The quality and reliability in additive manufacturing is an emerging area. To ensure process quality and reliability, the influence of all process parameters and conditions needs to be understood. The product quality and reliability characteristics, i.e., dimensional accuracy, precision, repeatability, and reproducibility are mostly affected by inherent and systematic manufacturing process variations. This paper presents research on dimensional quality and distortion analysis of AlSi10Mg thin-walled parts developed by a selective laser melting technique. The input process parameters were fixed, and the impact of inherent process variation on dimensional accuracy and precision was studied. The process stability and variability were examined under repeatability and reproducibility conditions. The sample length (horizontal dimension) results revealed a 0.05 mm maximum dimensional error, 0.0197 mm repeatability, and 0.0169 mm reproducibility. Similarly, in sample height (vertical dimension) results, 0.258 mm maximum dimensional error, 0.0237 mm repeatability, and 0.0863 mm reproducibility were observed. The effect of varying design thickness on thickness accuracy was analyzed, and regression analysis performed. The maximum 0.038 mm error and 0.018 mm standard deviation was observed for the 1 mm thickness sample, which significantly decreased for sample thickness ≥2 mm. The % error decreased exponentially with increasing sample thickness. The distortion analysis was performed to explore the effect of sample thickness on part distortion. The 0.5mmthickness sample shows a very high distortion comparatively, and it is reduced significantly for >0.5 mm thickness samples. The study is further extended to examine the effect of solution heat treatment and artificial aging on the accuracy, precision, and distortion; however, it did not improve the results. Conclusively, the sample dimensions, i.e., length and height, have shown fluctuations due to inherent process characteristics under repeatability and reproducibility conditions. The ANOVA results revealed that sample length means are not statistically significantly different, whereas sample height means are significantly different. The horizontal dimensions in the xy-plane have better accuracy and precision compared to the vertical dimension in the z-axis. The accuracy and precision increased, whereas part distortion decreased with increasing thickness. [ABSTRACT FROM AUTHOR]

Operational amplifiers (opamps) are often designed in stages. Distortion analysis of multistage opamps is challenging due to multiple non-linearity sources. Therefore, one effective analysis method is to consider a multistage opamp model as a cascade of condensed stages, with each stage modelled by one weakly non-linear element. Then, in order to obtain a satisfactory distortion model, accurate characterisation of the non-linearity of each stage is necessary. In this Letter, the authors propose an analytical calculation method for modelling the weak non-linearity of an amplifier stage consisting of several interconnected transistors. A stage circuit model created by this method can be used to produce analytical harmonic distortion characterisation of closed-loop circuits with peripheral elements. Numerical accuracy of the analytical method has been validated by transistor-level simulation. [ABSTRACT FROM AUTHOR]

A handy formula is presented to evaluate the effects of random surface errors on average power pattern for distorted reflector antennas. Based on the previous work of Rahmat-Samii on average power pattern degradation for random surface errors, the surface distortion-induced phase error is expanded into a second-order Taylor series expansion in radiation integral. With the probabilistic distribution of phase errors, the closed-form expressions of average power pattern and variance on boresight gain and sidelobe levels are demonstrated by this handy formula. To show the effectiveness of this formula, its applicability region is derived. The derivation clearly shows that when the root-mean-square amplitude of surface distortion is below $\lambda $ /30, the handy formula presents a good agreement with the exact one in boresight gain within a 0.1 dB computational accuracy. Comparing with the previous work, this formula can estimate the boresight gain loss by hand quickly without the exponential calculation, which will benefit the antenna design. [ABSTRACT FROM AUTHOR]

Residual stress on the machined surface and the subsurface is known to influence the distortion of thin-walled parts. Therefore, it is essential to predict the distribution of surface residual stress accurately. In this paper, the coupled distribution law of initial residual stress and machining-induced residual stress is investigated. Firstly, a model with initial residual stress is established and incorporated into thermal mechanical coupled finite element model of 2-D cutting. Then, a tensile fixture is designed to impose initial stress into a thin-walled part of Al-6061, and cutting experiments are carried out. The residual stress distribution is measured by X-ray diffraction/electropolishing method. The results of experiments and simulation show that in the plastic deformation zone, the initial residual stress has no significant influence on the distribution of the machining-induced residual stress. In the elastic deformation zone, the stress that linear grows along depth from zero to initial residual stress is superimposed on machining-induced residual stress. The mathematical model of stress coupling distribution on the surface of thin-walled parts is established by numerical method. Finally, it is found that the effect of coupled stress distribution on distortion is more significant with the decrease of thickness (from 3 to 0.5 mm) of the thin-walled parts. [ABSTRACT FROM AUTHOR]

An analytical model based on a theoretical model established in the previous work (part 1) is developed. The analytical model considers the particular case of an instantaneous high-density heat source acting on a thin pre-stressed plate. It calculates the plastic strain and the area of the zone of plastic deformation. A theoretical study is performed in order to quantify the major factors that influence the plastic strain formation. Furthermore, the work presents a calculation procedure for distortion analysis of large and complex structures, intended to be used for solving industrial tasks. The calculation procedure consists of a combination of the analytical solution and an elastic finite element analysis with the aid of the inherent strain approach. Various aspects of its application are also discussed. The calculation procedure is finally explained using a simple example. Its reliability and practicability are demonstrated through verification and validation studies. The work is dedicated to the thermal straightening of thin-walled welded structures; however, it can also be related to other processes. [ABSTRACT FROM AUTHOR]

The quality and reliability in additive manufacturing is an emerging area. To ensure process quality and reliability, the influence of all process parameters and conditions needs to be understood. The product quality and reliability characteristics, i.e., dimensional accuracy, precision, repeatability, and reproducibility are mostly affected by inherent and systematic manufacturing process variations. This paper presents research on dimensional quality and distortion analysis of AlSi10Mg thin-walled parts developed by a selective laser melting technique. The input process parameters were fixed, and the impact of inherent process variation on dimensional accuracy and precision was studied. The process stability and variability were examined under repeatability and reproducibility conditions. The sample length (horizontal dimension) results revealed a 0.05 mm maximum dimensional error, 0.0197 mm repeatability, and 0.0169 mm reproducibility. Similarly, in sample height (vertical dimension) results, 0.258 mm maximum dimensional error, 0.0237 mm repeatability, and 0.0863 mm reproducibility were observed. The effect of varying design thickness on thickness accuracy was analyzed, and regression analysis performed. The maximum 0.038 mm error and 0.018 mm standard deviation was observed for the 1 mm thickness sample, which significantly decreased for sample thickness ≥2 mm. The % error decreased exponentially with increasing sample thickness. The distortion analysis was performed to explore the effect of sample thickness on part distortion. The 0.5 mm thickness sample shows a very high distortion comparatively, and it is reduced significantly for >0.5 mm thickness samples. The study is further extended to examine the effect of solution heat treatment and artificial aging on the accuracy, precision, and distortion; however, it did not improve the results. Conclusively, the sample dimensions, i.e., length and height, have shown fluctuations due to inherent process characteristics under repeatability and reproducibility conditions. The ANOVA results revealed that sample length means are not statistically significantly different, whereas sample height means are significantly different. The horizontal dimensions in the xy-plane have better accuracy and precision compared to the vertical dimension in the z-axis. The accuracy and precision increased, whereas part distortion decreased with increasing thickness.

The work deals with the elastic-plastic thermo-mechanical deformation process after spot heating of large thin plates. It promotes a new theoretical model of the process. The main target is to clarify the kinetics of the plastic strain formation during thermal straightening and to explore the main interactions. For this purpose, a simplified mechanical problem is formulated and applied. As a result, definite thermo-mechanical relations between temperature, initial strain, and accumulated plastic strain are obtained. Finally, a verification study is presented and discussed. The results contribute to extending the knowledge about the process and to establishing a theoretical background for development of applied analytical or analytical-numerical approaches for practical use in the designing and planning phases in welding production. An application to a particular case is described in an accompanying paper (part 2). [ABSTRACT FROM AUTHOR]

Although in the past complicated and often considered ‘exotic’ process, hot stamping of steel is now widely used in the automotive industry and for some safety components it becomes obligatory. The hot stamped parts are used in regions where very high strength is required. But for some applications also ductility needs to be incorporated in parts to guide the absorption of energy under crash loading, for other the material thickness has to be reduced smoothly due to lightweight. This will be achieved by tailoring the material properties within the component. This new generation of hot formed parts is already standard in the market, but still difficult in the engineering. And the next one is already in start position – aluminum warm forming is planned as a substitution of the heavier steels for structural parts, but newly also for outer panels, where they have to fulfil all requirements on visible parts. Light, strong, accurate, high quality and warm formed to improve the formability of the material. This paper describes successful engineering methods in virtual hot stamping process with tailored properties and of warm and hot formed aluminum parts. [ABSTRACT FROM AUTHOR]

This paper introduces a new technique for the efficient computation of intermodulation distortion in radio frequency circuits that contain microelectromechanical system (MEMS) variable capacitors using moments analysis. This method is applied to an extended harmonic balance formulation, which contains the nonlinear equations that describe the dynamic mechanical behavior of MEMS variable capacitors, in addition to the nonlinear electric circuit equations. As a result, the moments method becomes a general multi-domain simulation method for quantifying nonlinear intermodulation distortion, while presenting significant computational cost reduction over harmonic balance-based methods. [ABSTRACT FROM PUBLISHER]

In this paper the fault diagnosis of multiple faults in linear circuits is studied for distortion analysis for 2nd and 3rd harmonic components by considering a state variable filter circuit. To study the testability of the circuit the distortion analysis is plotted for various fault conditions. The sensitivity of the output signal with respect to the faults along with pole-zero analysis is obtained. The transfer function of the state variable filter considered for the analysis is given by: [ABSTRACT FROM AUTHOR]

This letter briefly presents an interesting set of results from a non-destructive magnetic measurement method named as the distortion analysis of magnetic excitation (DAME). The time derivative of the excitation voltage ( V E ) across the coil around the electromagnetic (EM) yoke plotted as a function of total applied voltage ( V T ) (named as the DAME profile) truly reflects the magnetisation behaviour of the ferromagnetic material introduced between the poles of the EM yoke to close the magnetic flux path. The shape of the DAME profile with a peak and trough clearly reflects the subtle changes in the composition, microstructure, grain orientation and stress through their effect on the magnetisation process in the ferromagnetic material placed between the poles of the EM yoke. This letter shows that the DAME profile measurement is a simple non-destructive evaluation (NDE) method to detect and determine variations in the properties of ferromagnetic materials and has tremendous potential for several applications related to the evaluation of ferromagnetic materials and components. [ABSTRACT FROM AUTHOR]

This paper presents a method to characterize a multi-dimensional polynomial current and charge source models needed for a distortion contribution analysis technique that can identify the dominant nonlinearities and different mixing mechanisms. A separate model characterization step with carefully chosen test signals is used to break the inherent input–output correlation that otherwise complicates the model fitting. The proposed Volterra-on-top-of-harmonic-balance technique and improved polynomial fitting are then verified through the analysis of a 100-W LDMOS RF Doherty amplifier, which showed that, in this circuit, the cubic nonlinearity of the gate capacitance is the main culprit of AM–PM distortion. [ABSTRACT FROM PUBLISHER]

The influence of ferritic steel samples with different case-depths on the distortion behaviour of magnetic excitation voltage has been investigated. The systematic changes in the height and position of the peak and the trough on the ((dVE/dt) vs.VT) profile (distortion analysis of the magnetic excitation, DAME profile) reflect the difference in the magnetization process and hence the effect of distortion ofVEin samples with different case-depths. This study shows the potential of this simple DAME method for evaluation of ferromagnetic steel components. [ABSTRACT FROM AUTHOR]

This paper uses hand analysis and a new fully numerical distortion contribution analysis technique to explain and optimize the nonlinear performance of analog circuits. Several example circuits are studied, where mixing of nonlinear distortion from one harmonic band to another is important. In some circuits the band-to-band mixing can be employed to reduce the overall distortion. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new and accurate experimental method for determining resonant frequencies of MEMS. [•] The method is based on harmonic distortion analysis of MEMS electrical voltage output. [•] Development of electrostatic energy harvesters as test samples. [•] Comparison with measurements carried out by DLTS system are presented. [•] An uncertainty as low as one part in 103 is achievable with this technique. [Copyright &y& Elsevier]

This study presents distortion analysis of the fully differential Gm‐C filters in which the imbalance of the differential input voltages is taken into consideration. Closed‐form equations expressing distortions of differential‐mode (DM) output voltages as functions of DM and common‐mode input voltages are developed. It was found that the HD3 of the DM output voltage is independent of the input imbalance. On the contrary, the HD2 of the DM output voltage is directly dependent upon the input imbalance. Simulation results are shown to be in good agreement with the analytical results. [ABSTRACT FROM AUTHOR]

In this paper, we perform the theoretical analysis and experimental demonstration of an on-chip implementation of a Ku-band nanosecond scale time-stretching (TS) system in a 130-nm IBM 8RF CMOS process. The theory of the TS system is applicable to general TS systems. In this study, we explain the impact of the time-bandwidth product (TBP) on practical design considerations and derive the error and distortion of a general TS system based on a dispersive delay line with perfect linear group delay and all pass amplitude characteristic. We also derive the time resolution of a general TS system using both the principle of uncertainty as well as the short time Fourier transform method. This fundamental result enables a designer to understand the qualitative relationship between the TBP and the best possible resolution of the TS system. Finally, we experimentally demonstrate the TS system on chip with nanosecond group-delay variance and 12–16-GHz bandwidth. This demonstration indicates the potential for implementation of more complicated time-scaling signal-processing systems on chip, as well as a quantification of the error and distortion for such systems. [ABSTRACT FROM PUBLISHER]

The Gauss conformal mappings (GCMs) of an oblate ellipsoid of revolution to a sphere are those that transform the meridians into meridians, and the parallels into parallels of the sphere. The infinitesimal-scale function associated with these mappings depends on the geodetic latitude and contains three parameters, including the radius of the sphere. Gauss derived these constants by imposing local optimum conditions on certain parallel. We deal with the problem of finding the constants to minimize the Chebyshev or maximum norm of the logarithm of the infinitesimal-scale function on a given ellipsoidal segment (the region contained between two parallels). We show how to solve this minimax problem using the intrinsic function fminsearch of Matlab. For a particular ellipsoidal segment, we get the solution and show the alternation property characteristic of best Chebyshev approximations. For a pair of points relatively close in the ellipsoid at different latitudes, the best minimax GCM on the segment defined by these points is used to approximate the geodesic distance between them by the spherical distance between their projections on the corresponding sphere. This approach, combined with the best locally GCM if the points are on the same parallel, is illustrated by applying it to some case studies but specially to a 10° × 10° region contained between portions of two parallels and two meridians. In this case, the maximum absolute error of this spherical approximation is equal to 2.9 mm occurring at a distance about 1,360 km. This error decreases up to 0.94 mm on an 8° × 8° region of this type. So, the spherical approximation to the solution of the inverse geodesic problem by best GCM can be acceptable in many practical geodetic activities. [ABSTRACT FROM AUTHOR]

This paper presents an analysis framework for estimating spatio-temporal distortion associated with data-gathering algorithms in sensor networks. We assume that the underlying data field being sensed is spatially and temporally correlated and that the sink node performs real-time reconstruction of the field. Unlike existing work, the proposed analysis framework assumes realistic transmission schemes and network/routing parameters, such as congestion and limited transmission range. Our simulations show that, even for a simple collision-free transmission scheme and regular deployment patterns, the distortion analyses yield starkly different results, compared with the analyses performed in the absence of these assumptions. The analytical method presented in this paper could easily be extended to consider the real-time data-reconstruction problem under different transmission schemes, node distributions, and reconstruction methods. [ABSTRACT FROM AUTHOR]

In this paper, a Volterra analysis built on top of a normal harmonic balance simulation is used for a comprehensive analysis of the causes of AM-PM distortion in a LDMOS RF power amplifier (PA). The analysis shows that any nonlinear capacitors cause AM-PM. In addition, varying terminal impedances may pull the matching impedances and cause phase shift. The AM-PM is also affected by the distortion that is mixed down from the second harmonic. As a sample circuit, an internally matched 30-W LDMOS RF PA is used and the results are compared to measured AM-AM, AM-PM and large-signal S11. [ABSTRACT FROM AUTHOR]