Spur Model Research Articles

A Novel Model of an S-Shaped Tooth Profile Gear Pair with a Few Pinion Teeth and Tooth Contact Analysis Considering Shaft Misalignments

Due to the special meshing of convex and concave tooth profiles, an S-shaped tooth profile gear with a few teeth has the advantage of reducing the contact stress and improving the contact ratio. However, the theoretical inseparability of the center distance of an S-shaped tooth profile and shaft misalignments, including center distance errors and axis parallelism errors caused by manufacturing or installation errors, can easily cause tip contact and produce transmission errors. Accordingly, it is necessary to analyze the influence of shaft misalignments on the meshing performance. In this paper, a unified mathematical model of spur and helical gears with an S-shaped tooth profile is established and an analytic method for determination of the contact pattern, meshing path, and transmission error of a gear pair with shaft misalignments is proposed. Then, the validity of the analytic method is proved by practical examples and the influence of shaft misalignments on the contact pattern of an S-shaped tooth profile gear pair is obtained. Through comparison with an involute gear with the same parameters, it is found that shaft misalignments within a certain range result in an acceptable transmission error and contact area migration of the S-shaped tooth profile gear pair similar to that of the involute gear pair.

PLL Fractional Spur’s Impact on FSK Spectrum and a Synthesizable ADPLL for a Bluetooth Transmitter

In this work, we present an open-source fully-synthesizable fractional-N all-digital phase-locked loop (ADPLL) designed for a Bluetooth low-energy (BLE) transmitter (TX) along with a semi-analytical model of the PLL fractional spur’s impact on the BLE output spectrum. Based on the model and the BLE specification for spur emission, a requirement for the PLL fractional spurs is derived. To meet the derived spectral mask by reducing the fractional spurs, a novel synthesizable two-step time to digital converter (TSTDC) that employs embedded TDC (EMBTDC) as coarse and Vernier delay-line TDC (DLTDC) as fine TDC is proposed. We also present a digital calibration scheme to compensate for the nonlinearity induced by the place-and-route (P&R) tool. The PLL is fabricated in 12-nm FinFET and demonstrated in a BLE-TX. The measured BLE transmissions satisfy the standard requirements thanks to the reduced fractional spurs. In a standalone PLL mode, the proposed TSTDC and calibration scheme reduced the fractional spurs by 14.3 dB compared to only using an EMBTDC in near-integer <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$</tex-math> </inline-formula> operation. The PLL supports a frequency range of 1.8–2.7 GHz and consumes 3.91 mW at 2.4006 GHz achieving figure of merit (FoM) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 220.7 dB in fractional-N mode with a 40 MHz reference, occupying an area of 0.063 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> . A highly automated design flow is used for the PLL to lower the barrier for new developers and reduce the porting cost.

SPUR-27 - Psychometric Properties of a Patient-Reported Outcome Measure of Medication Adherence in Chronic Obstructive Pulmonary Disease.

People living with COPD who struggle to take their medicines often experience poorer health outcomes such as exacerbations of symptoms, more frequent and lengthy hospital admissions, and worsening mortality rates. This study aimed to evaluate the psychometric properties of the previously validated SPUR-27 model, a multi-factorial model of medication adherence. This cross-sectional study was conducted with 100 adult patients living with COPD in a hospital setting in Southwest London. Medication adherence was assessed using a shortened SPUR model (SPUR-27) against the validated Inhaler Adherence Scale (IAS) as a comparator. In addition, objective medication adherence data, presented as the Medication Possession Ratio (MPR), were derived from patient medical and pharmacy records. The COPD Assessment Tool (CAT) score was used to examine the relationship between medication adherence and COPD symptom severity. Reliability of SPUR-27 was assessed using internal consistency estimates. Exploratory factor analysis, partial confirmatory factor analysis, and maximum likelihood analysis were conducted in conjunction with construct, concurrent, and known-group validity testing to explore the psychometric properties of the SPUR model in this population. A 7-factor model for SPUR-27 was derived with adequate factor loadings. SPUR (α=0.893) observed strong internal consistency (>0.8). The model was significantly positively correlated with IAS score (p<0.001) as well as MPR (p<0.01). A significant (p<0.01) relationship between poor medication adherence and worsening symptom severity, as defined by the CAT score, was identified for SPUR (χ 2 = 8.570) using Chi-Square analysis. Furthermore, SPUR-27 demonstrated early evidence of validity with good incremental fit indices: NFI (0.96), TFI (0.97), and CFI (0.93) were all reported as >0.9 in addition to the RMSEA, which was <0.08 (0.059). SPUR demonstrated strong psychometric properties in patients living with COPD. Further work should look to examine the test-retest reliability of the model and its application in broader sample populations.

Modeling and Removing Doppler Division Multiplexing Spurs in Automotive MIMO Radar

Doppler division multiplexing (DDM) is a popular slow-time modulation technique for automotive multiple-input and multiple-output (MIMO) radars. It requires accurate transmit phase shifters to avoid artifacts such as spurs that would degrade the radar system’s performance. This article proposes a system impact analysis of the constellation imbalance of the phase shifter. The spurs formation is modeled in a second part to understand the information they convey on the constellation imbalance. Subsequently, this information is exploited as a base for a novel constellation imbalance estimation algorithm. The estimation is finally utilized to predistort the phase shifter. The DDM spur model and the constellation imbalance estimation method are evaluated on a recorded automotive radar dataset. The results show that the imbalance in the phase shifter constellation can be reduced such that all spurs are suppressed below the noise floor. With the presented method, the DDM MIMO radar system can autonomously evaluate when recalibration is needed and perform self-calibration on the road to maintain the system’s performance throughout its life cycle.

A Holistic Approach to Strategic Sustainable Development of Urban Voids as Historic Urban Landscapes from the Perspective of Urban Resilience

Since complex urban systems are a combination of different spatial typologies and may have various complex characteristics (human, environmental, social, economic, political, and cultural), decision-making cannot be done without a holistic approach and complex analysis and evaluation of the possible development scenarios. This is especially true in today’s world, where spatial and urban planning must consider various objectives such as sustainable development, accessibility, landscape characteristics, and public interests on a strategic level. This results in the need to use appropriate decision support and decision-making tools in the strategic urban planning process of complex urban environments with Historic Urban Landscapes (HUL) characteristics to improve urban development and resilience. The proposed evaluation model, “Strategic Planning for Urban Resilience—SPUR model,” is based on a holistic approach to spatial planning with an emphasis on the strategic sustainable development of urban voids as HULs and was tested on the case study of the Delta area in the City of Rijeka, Croatia. The proposed holistic approach can help in scenario building, evaluation, and selection of planning alternatives, as well as decision-making processes in urban management, by enabling the evaluation and control of complex scenarios from a sustainable development perspective.

SPUR: psychometric properties of a patient-reported outcome measure of medication adherence in type 2 diabetes

IntroductionPoor medication adherence is associated with worsening patient health outcomes and increasing healthcare costs. A holistic tool to assess both medication adherence and drivers of adherence behaviour has yet to...

Determination of transmission error in spur gear by numerical approach

The problem of transmission error is nowadays a very discussed topic in the field of vibration and noise generation. When tooth designing the numerical simulations can be used to minimize the transmission error, which fundamentally influences the gearbox behavior. For this purpose, a parametric model of straight tooth spur was developed. Subsequently, a calculation approach was used using the finite element method to determine the static error of the transmission at various load states, axial distance variations, and tooth shape elevation modifications. Based on the obtained results, it is possible to find a suitable type of tooth for the given operation conditions.

GENERATION OF ULTRAFAST TRANSIENT ACID SPIKES IN HIGH-TEMPERATURE WATER IRRADIATED WITH LOW LINEAR ENERGY TRANSFER RADIATION

Monte Carlo track chemistry simulations of the low linear energy transfer radiolysis of pure, deaerated liquid water have been used in combination with a spherical spur model to examine the effect of temperature on the in situ formation of H3O+ ions and the corresponding abrupt transient “acid-spike” response that is observed after irradiation. The magnitude and duration of this acid-spike effect were found to be a very sensitive function of temperature. At 25 °C, it is most intense at times less than ∼1 ns, with a pH of 3.3 remaining nearly constant. In contrast, at higher temperatures, there is an increasingly acidic but much shorter pH response. At 350 °C, the pH is around 1.7 on a time scale of ∼10 ps. At longer times, the pH gradually increases for all temperatures, ultimately reaching a constant value corresponding to the non-radiolytic, pre-irradiation concentration of H3O+ arising through water’s autoprotolysis at ∼1–10 μs following irradiation. It does not appear that this transient acid-spike ef...

A torsional model of multi-stage gears – influence of external excitations and tooth shape modifications

In this paper, a torsional dynamic model of multi-stage idler spur and helical gears is presented which combines mesh internal excitations and external forcing terms such as time-varying external torque. Each contact line in the various base planes is discretized in elemental cells which are all attributed a time-varying mesh stiffness element and initial separation to account for tooth shape deviations from ideal involute flanks. The mesh stiffness functions are estimated from the formulae of Weber & Banaschek and their relative phasing is determined based on gear geometry and relative positioning. The corresponding non-linear differential system is solved by combining a Newmark’s numerical time-step integration scheme and a normal contact algorithm. A number of simulation results are presented on the combined influence on dynamic tooth loads of errors and shape deviations along with external excitations.

Analysis of Phase Truncation Error Based on Multi-Path Pseudo-Interleaved Direct Digital Frequency Synthesis

Low output frequency and spurs are main imperfections in direct digital frequency synthesis (DDFS). For increasing output frequency determined by sampling rate, the structure of multi-path pseudo-interleaved DDFS is proposed. However, it introduces more complex phase truncation error than single path DDFS. In order to analyze the effect of phase truncation error, the model of pseudo-interleaved DDFS with phase truncation is established. Based on the model, the distribution and amplitude of spur caused by phase truncation are discussed and calculated. Then some important conclusions are drawn and proved by experiment, which can provide theoretical supports for spurious performance evaluation and parameter selection while designing signal source or clock generator based on pseudo-interleaved DDFS.

Positron annihilation studies in binary solid solutions and mechanical mixtures of lanthanide dipivaloylmethanate complexes

Measurements using positron annihilation lifetime (PALS) and Doppler broadening annihilation radiation lineshape (DBARLS) spectroscopies were performed in several lanthanide dipivaloylmethanate complexes, Ln(dpm)3 where Ln=Sm3+, Gd3+, Tb3+, Ho3+, Er3+, Yb3+ and dpm=2,2,6,6-tetramethyl-3,5-pentanedionate, and also on their binary solid solutions and mechanical mixtures, biphasic systems, of the general formula Ln1−xEux(dpm)3. Expressive positronium formation was observed in all Ln(dpm)3 complexes, except in Eu(dpm)3 complex. The results indicate formation of solid solutions in the Sm3+, Gd3+and Tb3+ systems, where total inhibition of positronium formation was observed. A Stern–Volmer type equation, I30/I3=1+kx, was used to fit the data, enabling the calculation of the inhibition constants, k. A mechanical mixture behavior, with linear variation of I3 between the I3 values of the pure complexes, was observed in systems containing Ho3+, Er3+ and Yb3+ complexes, where no effective solid solution formation occurred due to differences between the crystalline structures of these complexes and Eu(dpm)3. No positronium quenching reactions were observed in the solid solutions. DBARLS results confirmed those of PALS, evidencing that the positron annihilation spectroscopies are useful techniques to characterize the formation of solid solutions. PALS measurements at 80K were performed in the Sm1−xEux(dpm)3 and Gd1−xEux(dpm)3 solid solutions. The results indicate that, despite a contraction in the crystalline structures, the solid solution structure remains intact at low temperatures. The temperature dependence of the inhibition constant do not seem to be understood from the positronium formation spur model and might be related to intra and intermolecular energy and charge transfer processes in the solid solutions, which is currently being studied.

Evaluation of a Mixed CAD Gear Modeling from Time and Precision Point of View

Abstract The aim of the paper is to present an evaluation of a new mixed CAD modeling method, capable to universally build surfaces and solid models of gears. The proposed CAD solution builds gear models, primary not for a visual simulation of the gearing processes, but for complex gearing- and FEA studies in virtual environment. Localization of the contact paths of gear pairs, virtual kinematic evaluations, rapid verification of newly developed gear types and FEA analysis requires satisfactorily precise surface and solid models. The known NURBS modeling methods are mainly based on the analytical equations of the flanks of the teeth surfaces. The bottom and tip surfaces of the teeth, are very important in meshing and FEA studies, and generally cannot be built from the meshing equations. As the new mixed modeling method proposes a simplified and quick CAD modeling procedure, with flexible modeling options like rapid tool profile modifications, an evaluation of the obtained models must be made, from both: generating time and precision point of view. For this purpose, a model of a spur cylindrical gear (generated by a convolute helical hob) is built using the Solid Boolean Subtraction method and is compared with the gear generating process using a new mixed CAD method.

Sequential radiation chemical reactions in aqueous bromide solutions: pulse radiolysis experiment and spur model simulation

Pulse radiolysis experiments were carried out to observe transient absorptions of reaction intermediates produced in N2O- and Ar-saturated aqueous solutions containing 0.9–900 mM NaBr.

Positronium formation in solid transition metal losartanates complexes

In this Letter, positron annihilation lifetime (PALS) measurements were performed in transition metal losartanates complexes, MT(Los)2, and in potassium losartanate, KLos, in order to built up insights about the positronium formation mechanism in molecular environment. A correlation was obtained between formation probability, I3, and the covalence of complexes, evaluated by molar electrical conductivity in dimethylformamide (DMF). Furthermore, some metallic ion properties, such as reduction potential and pauling electronegativity, were also correlated with I3. These results were analyzed in terms of the spur model and of the recently proposed mechanism, named cybotatic correlated system kinetic mechanism (CCSKM), which involves molecular excited states in positronium formation.

Gear and motor fault modeling and detection based on motor current analysis

This paper deals with the simulation of the dynamic behavior of induction motor/gear systems. The corresponding model combines: (i) a permeance network aimed at representing squirrel-cage induction motors and (ii) a 3D dynamic model of spur and helical gears including the shafts and bearings. Some classic motor defects (rotor eccentricity) and gear faults (tooth spalls) are considered and an iterative solution technique is presented which makes it possible to solve the coupled electro-mechanical problem. Based on a number of simulations, it is shown that the frequencies associated with defects can be identified and that distant detection and monitoring of tooth faults using stator currents seem promising alternatives to the classic techniques based on mechanical vibration analysis.

On the spur lifetime and its temperature dependence in the low linear energy transfer radiolysis of water

In the spirit of the radiation chemical "spur model", the lifetime of a spur (τ(s)) is an important indicator of overlapping spurs and the establishment of homogeneity in the distribution of reactive species created by the action of low linear energy transfer (LET) radiation (such as fast electrons or γ irradiation). In fact, τ(s) gives the time required for the changeover from nonhomogeneous spur kinetics to homogeneous kinetics in the bulk solution, thus defining the so-called primary (or "escape") radical and molecular yields of radiolysis, which are obviously basic to the quantitative understanding of any irradiated chemical system. In this work, τ(s) and its temperature dependence have been determined for the low-LET radiolysis of deaerated 0.4 M aqueous solutions of H(2)SO(4) and pure liquid water up to 350 °C using a simple model of energy deposition initially in spurs, followed by random diffusion of the species of the spur during track expansion until spur overlap is complete. Unlike our previous τ(s) calculations, based on irradiated Fricke dosimeter simulations, the current model is free from any effects due to the presence of oxygen or the use of scavengers. In acidic solutions, the spur lifetime values thus obtained are in very good agreement with our previous calculations (after making appropriate corrections, however, to account for the possibility of competition between oxygen and Fe(2+) ions for H˙ atoms in the Fricke dosimeter, an effect which was not included in our original simulations). In this way, we confirm the validity of our previous approach. As expected, in the case of pure, oxygen-free water, our calculated times required to reach complete spur overlap are essentially the same (within uncertainty limits) as those found in acidic solutions. This explicitly reflects the fact that the diffusion coefficients for the hydrated electron and the H˙ atom that are involved in the overall calculation of the lifetime of spurs in neutral or acidic media, respectively, are of similar magnitude over the 25-350 °C temperature range studied.

Muon Radiation in Methanol: In Support of the Spur Model

Abstract Different fractions of muon environments were studied in methanol within a temperature range of 177 K to 316 K. The diamagnetic fraction does not vary significantly with temperature, while the muonium (Mu) fraction decreases by a factor of 2 as temperature increases and the lost fraction increases with temperature at the expense of the Mu fraction It is likely that at low temperatures Mu becomes segregated from solvated electrons created in the spur leading to the increase in Mu fraction and decrease in lost fraction. As internal energy increases, the hydrogen bonding in methanol decreases. This can avoid separation of Mu from the solvated electrons in the radiolysis track increasing thus the likelihood of Mu being dephased by a solvated electron during an encounter. Our experimental data also suggests that the hot atom model is not appropriate to describe the thermalization of muons in methanol.

Time-dependent yield of the hydrated electron in subcritical and supercritical water studied by ultrafast pulse radiolysis and Monte-Carlo simulation

Fast kinetics and time-dependent yields of the hydrated electron (e(-)(aq)) in pure water under conditions of high temperature and pressure up to the supercritical region were investigated by picosecond and nanosecond pulse radiolysis experiments. More significant decays at short times followed by plateau components at longer times were observed with increasing temperature, suggesting faster spur reaction processes. In supercritical water, it was also found that the e(-)(aq) yields strongly depend on the pressure (density). Comparison of these measurements with Monte-Carlo computer simulations allowed us to identify spur reactions of e(-)(aq) that occur predominantly at high temperatures and also to provide new key information on certain spur model parameters. In particular, the experimental time-dependent e(-)(aq) yields were best reproduced if the electron thermalization distance decreases with increasing temperature. This "shrinkage" of spur sizes at high temperatures was attributed to an increase in the scattering cross sections of subexcitation electrons, likely originating from a decrease in the degree of structural order of water molecules as the temperature is increased.

A PLL based WSN transmitter and I/Q LO signal generator at 430–435 MHz

A fully integrated Phase-Locked Loop (PLL) based transmitter and I/Q Local Oscillating (LO) signal generator used for half-duplex Wireless Sensor Networks (WSN) transceivers is proposed. Instead of one 430---435 MHz PLL for frequency synthesizing, a 1.72---1.74 GHz PLL is designed together with a 1/4 frequency divider. Then the chip area of the inductors in the Voltage-Controlled Oscillator (VCO) is decreased to about 1/16, and I/Q dual-path LO signals can be obtained without additional power consumption. A Gray-code controlled prescaler is proposed to avoid the glitches and uncertain states, and then the frequency dividing accuracy is improved by 17%. A Gauss Frequency Shift Keying (GFSK) transmitter with a pipeline modulator is proposed, the 1st and 2nd Adjacent Channel Power Ratio (ACPR) are ?19.9 and ?20.7 dBc, respectively. A mathematical spur model of 1/4 frequency dividers is built here, and then a low-spur 1/4 frequency divider composed of our proposed improved Current Mode Logic (CML) latches is designed. The testing results show that the reference spurs are ?61.2 dBc@20 MHz and ?57.7 dBc@40 MHz at the output of the PLL, and ?70.5 dBc@20 MHz and ?66.6 dBc@40 MHz at the output of our 1/4 divider. With 2.6-mW power consumption, our proposed 1/4 frequency divider has a phase-noise contribution of only 0.5 dBc/Hz@500 kHz and 0.2 dBc/Hz@1 MHz.

Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350 °C: a Monte-Carlo simulation study

Monte-Carlo simulations of the radiolysis of the ferrous sulfate (Fricke) dosimeter with low-linear energy transfer (LET) radiation (such as (60)Co γ-rays or fast electrons) have been performed as a function of temperature from 25 to 350 °C. The predicted yields of Fe(2+) oxidation are found to increase with increasing temperature up to ∼100-150 °C, and then tend to remain essentially constant at higher temperatures, in very good agreement with experiment. By using a simple method based on the direct application of the stoichiometric relationship that exists between the ferric ion yields so obtained G(Fe(3+)) and the sum {3 [g(e(-)(aq) + H˙) + g(HO(2)˙)] + g(˙OH) + 2 g(H(2)O(2))}, where g(e(-)(aq) + H˙), g(HO(2)˙), g(˙OH), and g(H(2)O(2)) are the primary radical and molecular yields of the radiolysis of deaerated 0.4 M H(2)SO(4) aqueous solutions, the lifetime (τ(s)) of the spur and its temperature dependence have been determined. In the spirit of the spur model, τ(s) is an important indicator for overlapping spurs, giving the time required for the changeover from nonhomogeneous spur kinetics to homogeneous kinetics in the bulk solution. The calculations show that τ(s) decreases by about an order of magnitude over the 25-350 °C temperature range, going from ∼4.2 × 10(-7) s at 25 °C to ∼5.7 × 10(-8) s at 350 °C. This decrease in τ(s) with increasing temperature mainly originates from the quicker diffusion of the individual species involved. Moreover, the observed dependence of G(Fe(3+)) on temperature largely reflects the influence of temperature upon the primary free-radical product yields of the radiolysis, especially the yield of H˙ atoms. Above ∼200-250 °C, the more and more pronounced intervention of the reaction of H˙ atoms with water also contributes to the variation of G(Fe(3+)), which may decrease or increase slightly, depending on the choice made for the rate constant of this reaction. All calculations reported herein use the radiolysis database of Elliot (Atomic Energy of Canada Limited) and Bartels (University of Notre Dame) that contains all the best currently available information on the rate constants, reaction mechanisms, and g-values in the range 20 to 350 °C.