Non-ideal Parameters Research Articles

Understanding the influence of device, circuit and environmental variations on real processing in memristive memory using Memristor Aided Logic

Memristors have gained increasing interest recently as emerging memory technologies. Their unique ability to perform logic operations within the memory makes them even more attractive. MAGIC NOR is one such logic gate that can be integrated within memristive memory cells, thus opening possibilities for real in-memory computing. This paper explores the integration of MAGIC NOR gates within large-scale memory crossbar arrays. We evaluate both analytically and numerically different non-ideality parameters that influence the logic gate performance. First, we investigate the effect of parasitic resistance and capacitance within the memory array. Then, process and device variations are considered and modeled, as well as environmental conditions such as temperature and power supply variations. These non-idealities are formulated in the form of process corners that enable designers to estimate the effect of variations on their design in worst case scenarios, similar to the manner in which such effects are estimated in CMOS-based VLSI design.

Differential capacitance of ionic liquids according to lattice-gas mean-field model with nearest-neighbor interactions.

The Bragg-Williams free energy is used to incorporate nearest-neighbor interactions into the lattice gas model of a solvent-free ionic liquid near a planar electrode. We calculate the differential capacitance from solutions of the mean-field consistency relation, arriving at an explicit expression in the limit of a weakly charged electrode. The two additional material parameters that appear in the theory-the degree of nonideality and the resistance to concentration changes of each ion type-give rise to different regimes that we identify and discuss. As the nonideality parameter, which becomes more positive for stronger nearest-neighbor attraction between like-charged ions, increases and the electrode is weakly charged, the differential capacitance is predicted to transition through a divergence and subsequently adopt negative values just before the ionic liquid becomes structurally unstable. This is associated with the spontaneous charging of an electrode at vanishing potential. The physical origin of the divergence and the negative sign of the differential capacitance is a nonmonotonic relationship between the surface potential and surface charge density, which reflects the formation of layered domains alternatingly enriched in counterions and coions near the electrode. The decay length of this layered domain pattern, which can be many times larger than the ion size, is reminiscent of the recently introduced concept of "underscreening."

Convergence of strong shock waves in non-ideal magnetogasdynamics

The problem of a strong cylindrical shock wave collapsing at the axis of symmetry is studied in non-ideal magnetogasdynamics. The perturbation approach used in this work provides a global solution to the shock implosion problem in non-ideal magnetogasdynamics in contrast to Guderley’s asymptotic solution that holds in the vicinity of the axis of implosion. We analyze the flow parameters by expanding the solution in powers of time and found the similarity exponents as well as the corresponding amplitudes in the vicinity of the shock-collapse. Along with the higher-order terms in Guderley’s asymptotic solution, the leading similarity exponents have been refined near the center of convergence. The flow parameters and the shock trajectory have been drawn in the region extending from the piston to the center of collapse for different values of the adiabatic coefficient, shock cowling number, and non-ideal parameter.

Cylindrical shock wave generated by a moving piston in a rotational axisymmetric non-ideal gas with conductive and radiative heat-fluxes in the presence of azimuthal magnetic field

The propagation of a cylindrical shock wave in a rotational axisymmetric non-ideal gas with heat conduction and radiation heat-flux, in the presence of a spatially decreasing azimuthal magnetic field, driven out by a moving piston is investigated. The fluid velocities and the azimuthal magnetic field in the ambient medium are assume to be varying and obeying power laws. The gas is assumed to be electrically conducting and obey a simplified van der Waals equation of state. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Similarity solutions are obtained for the flow-field behind the shock and the effects of variation of Alfven Mach number, the conductive and radiative heat transfer parameters, the parameter of the non-idealness are worked out in detail. An increase in the value of Alfven Mach number or in the non-idealness parameter of the gas, decreases the compressibility of the gas and hence there is a decrease in the shock strength; whereas the reverse effects on compressibility and shock strength are obtained with an increase in conductive or radiative heat transfer parameter. It is shown that due to the consideration of rotating medium the compressibility of the gas and the shock strength increase. Further, it is investigated that with an increase in the parameters of conductive and radiative heat transfer the tendency of formation of maxima in the distribution of pressure and minimum in magnetic field and non-dimensional axial component of vorticity vector decreases. It is interesting to note that the pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the axis of symmetry, which is in excellent agreement with the laboratory conditions to produce a shock wave. A comparison between the cases of rotating and non-rotating medium is also made.

Shock wave driven out by a piston in a mixture of a non-ideal gas and small solid particles under the influence of the gravitation field with monochromatic radiation

Similarity solutions for a spherical shock wave in a mixture of small solid particles of micro size and a non-ideal gas are discussed under the influence of the gravitational field with monochromatic radiation. The solid particles are uniformly distributed in the mixture, and the shock wave is assumed to be driven by a piston. It is assumed that the equilibrium flow-conditions are maintained and the moving piston continuously supplies the variable energy input. Due to the central mass (m¯) at the origin (Roche model), the medium is considered to be under the influence of the gravitational field. In comparison to the attraction of the central mass at the origin, the gravitational effect of the mixture itself is neglected. The density of the undisturbed medium is assumed to be constant in order to obtain the self-similar solutions. The effect of the parameter of non-idealness of the gas b¯, the mass concentration of solid particles in the mixture μp, the ratio of the density of solid particles to the initial density of the gas Ga and the gravitational parameter G0 are obtained. It is shown that due to an increase in the gravitational parameter the compressibility of the medium at any point in the flow field behind the shock front decrease and the flow variables velocity, pressure, radiation flux and shock strength are increased. Also, an increase in the ratio of the density of solid particles to the initial density of the gas Ga and the gravitational parameter G0 has the same effect on the shock strength and the reverse effect on the compressibility. The non-idealness of the gas causes a decrease in the shock strength and widens the disturbed region between the piston and the shock.

Lifetime extension through Tj equalisation by use of intelligent gate driver with multi-chip power module

Typical high-current power modules used in traction and wind generation contain several dies in parallel. Non-ideal geometries and electrical parameter variations cause an unequal aging of each die which limits the effectiveness of using parallel devices. This paper presents an intelligent power module with a TSEP-based junction temperature measurement and internal temperature equalisation for extending its operational lifetime. As the magnitude and number of junction temperature cycles strongly dictate the power module lifetime, this paper focuses on the quantification of the lifetime gain via the application of common automotive drive cycles. Thus, a general thermal model is first deduced from the experimental results. The lifetime is then estimated using a stress-counting rainflow algorithm, a pre-determined damage law and a linear damage accumulation rule. Finally, in order to illustrate the lifetime extension, 160 drive cycles, including the legislatives drive cycles, are simulated. A lifetime gain of up to two times can be expected with the temperature equalisation method. Therefore, the initial investment on the developed intelligent power module is justified by the benefit of the large gain in lifetime and of the end-of life indication functions.

Planar dielectric cylindrical lens at 800 nm and the role of fabrication imperfections.

Conventional optical components have been proposed to realize high-quality line focusing with uniform intensity distribution such as cylindrical lenses, segmented wedge-arrays, or a combination of prisms and spherical mirrors. Numerous factors such as the manufacturing tolerances or the need for precise alignment of conventional lenses cause wave front aberrations that impact the performance of optical systems. These aforementioned limitations affect the uniformity of the intensity distribution and the intercept factor of lenses. Here, we experimentally demonstrate an integrable planar dielectric cylindrical lens made of titanium dioxide for uniform line focusing and discuss the sensitivity of its performance to fabrication imperfections originating from non-ideal geometrical parameters. The lens has a numerical aperture of 0.247, an intercept factor of 0.85, and an efficiency of 79% at 800 nm.

Spectral and Structural Characteristics for Cluster Systems of Charged Brownian Particles

We report on the results of analytic and numerical investigations of the dynamics for bounded ensembles of charged Brownian particles in the potential field of an electrostatic trap. Simulation has been performed for cluster systems consisting of (approximately up to one thousand) particles with the Coulomb interaction in a wide range of their parameters. The spectral structures and structural characteristics of the systems being simulated have been compared. The dependence of the form of the pair correlation function and the size of cluster systems on the temperature and the number of particles has been analyzed. The relation between the spectral density of displacements of the center of mass and of individual particles and the structural characteristics and nonideality parameter of the ensembles being modeled has been investigated.

A Robust Switched-Capacitor CDC

A capacitance-to-digital converter (CDC) designed to possess negligible sensitivity to non-ideal circuit parameters is presented in this paper. The scheme is based on switched capacitor integrating technique and the conversion process is such that the final output is fundamentally insensitive to leakage resistance and stray capacitance of the sensor, offset voltage and bias current of the opamp, delay, offset voltage, and bias current of the comparator, leakage current, delay, and charge injection of the switches employed, and so on. Such a characteristic is highly useful for precision measurement. The proposed CDC achieves it without any special compensating circuits, unlike some of the existing CDCs that partially meet the above feature. The performance of the CDC has been experimentally evaluated. Results show high insensitivity to the non-ideal circuit parameters. In addition, the worst case non-linearity error of the prototype CDC was found to be less than 0.1%, when tested for a range of 10 to 400 pF.

Correction to: Scheme for implementing dichotomic quantum measurements through non-ideal Stern–Gerlach setup

The value of the non-ideal parameter α has been incorrectly stated to be between 0 and 1 after derivation of the time evolution of the corrupt Gaussian distribution in Section 6.2.

Magnetosonic waves in a quantum plasma with arbitrary electron degeneracy.

Using a two-species quantum hydrodynamic model, we derive the quantum counterpart of magnetosonic waves, in a plasma with arbitrary degree of degeneracy and taking into account quantum diffraction effects due to the matter-wave character of the charge carriers. The weakly nonlinear aspects of the associated quantum magnetosonic wave are accessed by means of perturbation theory, with the derivation of a nonlinear evolution equation admitting solitons, namely, the Korteweg-deVries equation. The degeneracy and quantum diffraction effects on soliton propagation are determined. A qualitative change on weakly nonlinear magnetosonic waves appears when quantum diffraction matches certain conditions, producing shock solutions instead of solitons, within the approximation level. We also include explicit numeric estimates and a discussion on the coupling (nonideality) parameter for quantum plasmas with intermediate degeneracy degree.

Fluorescence Quenching and Energy Transfer Phenomena Associated with the Interactions of Terbium Ion and Humic Acid

Fluorescence of the hydrophobic acid fraction (HPOA) of Suwannee River natural organic matter and Tb3+ excitation spectra were measured in tandem using the instantaneous and time-resolved emission modes. The intensity of HPOA fluorescence decreased in the presence of Tb3+, while the intensity of the emission from Tb3+ cations bound by HPOA increased by up to several orders of magnitude due to energy transfer (ET) from HPOA to Tb3+ ions. To determine intrinsic ET and fluorescence quenching (FQ) coefficients, NICA–Donnan modeling was carried. It showed that phenolic groups in HPOA dominated both the ET and FQ processes and that the binding of Tb3+ by HPOA could be described using the non-ideality parameter nTb, median binding constant log $$\tilde{K}_{\text{Tb}}$$ for the phenolic sites and intrinsic ET and FQ coefficients (denoted as ηTbΦ and αTbΦ), and were 0.48, 8.5, 1385 and 0.12, respectively. The high value of the energy transfer coefficient of Tb3+ ions bound by the phenolic groups in HPOA is indicative of both the match between the electronic levels of the donor and acceptor, and the short distance between them. The deviation of the data of Nica–Donnan modeling of the ET and FQ dependence of versus [Tb]total for a 1.0 M ionic strength highlights the need to quantify the distribution of donor–acceptor distances in HPOA molecules in more detail.

An Improved Closed-Loop Switched Capacitor Capacitance-to-Frequency Converter and Its Evaluation

This paper presents a new capacitance-to-frequency converter (CFC) with high linearity and accuracy. In the CFC, the capacitance-to-frequency conversion is achieved using a negative feedback mechanism. In the feedback, the output frequency controls the charge injected by a switched-capacitor (SC) network such that the difference error is automatically minimized. The feedback mechanism ensures that the final output is insensitive to the nonlinearity errors of the units employed to realize the forward path, namely, a capacitance-to-voltage converter and a voltage-to-frequency converter. A simple error correction mechanism employed ensures that the digital output obtained is insensitive to the number of nonideal circuit parameters. The proposed converter uses a dc reference voltage for the excitation and helps to achieve high accuracy. A prototype of the improved CFC has been developed and tested for sensor capacitance $C_{x}$ in the range of 5–25 pF. A prototype of the conventional open-loop CFC was also developed, and the linearity has been evaluated. The proposed closed-loop approach has lower (0.1%) nonlinearity error compared to the conventional CFC (0.8%). This improvement is achieved without the use of any error-compensating schemes, and hence the complexity level of the system remains the same as that of any typical CFC. The response time of the CFC designed is about $400~\mu \text{s}$ for a 5–25 pF step change in $C_{x}$ . The results obtained from the prototype CFC confirmed its usefulness.

Optical millimeter wave signal generation with frequency 16-tupling using cascaded MZMs and no optical filtering for radio over fiber system

BackgroundAn optical Millimeter Wave (MM-Wave) generation with high frequency multiplication factor is very attractive solution to avoid the use of high frequency local oscillators at the central station. MethodsIn this paper, a frequency 16 tupling technique is demonstrated with the use of four cascaded MZMs. With the proper adjustment of DC bias of the Mach-Zehnder Modulators (MZM), amplitude and phases of the RF Local oscillators, MM-Wave with a frequency 16 times the input RF LO is demonstrated. ResultsThe cascaded structure has resulted very low modulation index of 2.827 and 54 dB and 42 dB of OSSR and RFSSR respectively. Analysis of both optical and RF sided band suppression ratios under non-ideal cases are also simulated and presented. Further, 10 Gbps NRZ data transmission performance over 50 km Single Mode Fiber (SMF) is also evaluated. ConclusionsThe proposed structure can tolerate up to few degrees of non-ideal parameter variation and is very simple to realize.

Flow behind an exponential shock in a rotational axisymmetric mixture of non-ideal gas and small solid particles with heat conduction and radiation heat flux

The propagation of exponential cylindrical shock wave in a rotational axisymmetric dusty gas with heat conduction and radiation heat flux, which has variable azimuthal and axial fluid velocities, is studied. The shock wave is driven out by a piston moving with time according to exponential law. Similarity solutions exist only when the surrounding medium is of constant density and constant angular velocity. The azimuthal and axial components of the fluid velocity in the ambient medium are assumed to be varying and obeying exponential laws. The dusty gas is assumed to be a mixture of small solid particles and non-ideal (or perfect) gas, in which solid particles are continuously distributed. In our model, it is assumed that the small solid particles are pseudo-fluid and the equilibrium flow-conditions are maintained in the flow-field. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with density and temperature. The effects of the variation of the heat transfer parameters, mass concentration of solid particles in the mixture Kp, the ratio of the density of solid particles to the initial density of the gas Ga and the parameter of the non-idealness of the gas b¯ are worked out in detail. It is found that an increase in the ratio of the density of solid particles to the initial density of the gas or the conductive heat transfer parameter Γc or the radiative transfer parameter ΓR increases the compressibility of the mixture in the flow field behind the shock, and hence there is an increase in the shock strength. Also, it is shown that an increase in the parameter of non-idealness of the gas b¯ has decaying effect on the shock wave.

Effect of Nonlinear Screening on a Complex Plasma Phase State

Applicability limit of the well-known phase diagram of dusty plasmas in $\kappa $ – $\Gamma $ plane ( $\kappa $ is structural parameter and $\Gamma $ is parameter of Coulomb nonideality) is under discussion. Existence of extensive domains with violation of plasma thermodynamic stability conditions (i.e., with negative isothermal compressibility) was also claimed if one uses well-known nonideal equations of state by (Hamaguchi S. et al. , Phys. Rev. E, 1997) and (Khrapak S. et al. , Phys. Rev. E, 2014). This paper is devoted to analysis of a range of applicability for basic assumption in Hamaguchi’s phase diagram, i.e., linearized (Debye) screening of macroions by microions, which leads to the Yukawa form for effective interactions between macroions. Parameters of nonlinear screening for macroions were calculated within differential Poisson–Boltzmann equation. Two effects were revealed as a result of such calculations: 1) decomposition of all microions onto two subclasses, free and bound ones, and 2) significant reduction of effective charge $\text{Z}^\ast $ of initial bare macroion Z under nonlinear screening by small high-density envelope of bound ions. This effect leads to a renormalization of initial $\Gamma $ and $\kappa $ into $\Gamma ^\ast $ and $\kappa ^\ast $ ( $\Gamma ^\ast , $\kappa ^\ast ). The main physical assumption is phase states of complex plasma under nonlinear screening, which are still the same as on the initial phase diagram, but in $\kappa ^\ast $ – $\Gamma ^\ast $ plane instead of $\kappa $ – $\Gamma $ one. Corresponding calculated shifts of phase states are discussed and illustrated.

Polarized reflectivity properties of shock-compressed plasma with strong interaction of particles

New results of s- and p-polarized reflectivity measurements on non-ideal plasma at the frequency of external electromagnetic field νlas = 2.83×1014 s−1, the plasma density ρ = 1.8 g/cm3 and the parameter of Coulomb non-ideality of plasma Γ = 1.4 are presented. Using a Fermi-like density profile along the shock wave front, the reflectivity coefficients of non-ideal plasma were calculated for newly obtained experimental data. As physically expected, a single profile is sufficient to obtain good agreement with the experimental data at all investigated optical laser frequencies.

Macroions non-linear screening in complex plasma

The base for consideration is the well-known phase diagram of dusty plasma for an equilibrium charged system with the Yukawa potential in Γ−κ plane, where Γ is a Coulomb non-ideality parameter, κ is a screening parameter, from [Hamaguchi S et al 1997 Phys. Rev. E 92 4671]. Two-component highly asymmetric electroneutral systems of classical macroions with the charge Z and point-like opposite charged microions are considered in the case of big non-uniformity around macroions. Linear screening approximation is not valid for a considerable part of characteristic parameters of substantial dusty plasma. The Poisson–Boltzmann equation is solved numerically in electroneutral Wigner–Seitz cell to consider non-linear screening of a macroion by microions. Distributions of microions and non-linear potentials are calculated. This allows to make charge renormalization and to consider not a real charge Z but an effective one Z*. Also, it is shown that the initial phase changes as non-linear screening is taken into account.

Microwave photonics reconfigurable mixer based on polarization modulator

A reconfigurable and stable mixer is proposed and demonstrated in this paper. It mainly consists of a dual-driven Mach–Zehnder modulator and a polarization modulator with several polarization controllers (PC) and polarizers (Pol). According to the theoretical analysis, different functions (such as single ended mixer, balanced mixer, I/Q mixer and image rejection mixer) can be realized by adjusting the PCs and Pols. The simulation results verify the possibility of multi-functions that realized by the reconfigurable mixer. In addition, another research on how the non-ideal parameters affect the image rejection ratio (ISR) and conversion efficiency of the mixer is also carried. The results show that both of them perform better as the extinction ratio gets higher. However, they are incurring a sharp decrease if the DC bias points deviate from the settled values. In the meantime, the results also indicate that the higher modulation indices lead to a better ISR. A 57.12 dB ISR can be achieved with conversion efficiency of − 9.53 dB.

On the RH relations across weak and strong shocks in van der Waals gases

The Rankine–Hugoniot (RH) jump relations for normal shock waves in van der Waals fluids have been studied in order to improve a theoretical understanding of those shock related phenomena as observed in a real atmosphere which cannot be accounted for by the ideal gas model. The RH jump relations for the pressure, density, particle velocity, temperature, speed of sound, adiabatic compressibility and change-in-entropy across the shock front have been analysed in terms of the non-idealness parameter of the gas, downstream Mach number and adiabatic index of the gas. Further, as the strength of shock waves may range from weak to strong, the convenient forms of RH jump relations for weak and strong shock waves have been discussed, simultaneously. Finally, the effects on the flow-field behind the shock front have been explored due to the non-idealness parameter of the gas, downstream Mach number and adiabatic index of the gas.