Inductance Extraction Research Articles

Inductance of superconductor integrated circuit features with sizes down to 120 nm

Data are presented on the inductance of various features used in superconductor digital integrated circuits: microstrip and stripline inductors with linewidths down to 120 nm and different combinations of ground plane layers, effect of perforations of various sizes in the ground planes and their distance to the inductors on inductance, inductance of vias of various sizes between adjacent layers, inductance of composite vias between distant superconducting layers. Test circuits used for the measurements were fabricated in a new 150 nm node of a fully planarized process with eight niobium layers developed at MIT Lincoln Laboratory for superconductor electronics as well as in our standard SFQ5ee and SC1 fabrication processes with 250 nm minimum feature size. The new SC2 process utilizes 193 nm photolithography in combination with plasma etching and chemical mechanical planarization of interlayer dielectrics to define inductors with linewidth down to about 100 nm on critical layers. The standard processes use 248 nm photolithography. The measured data are compared with the results of inductance extraction using software packages InductEx and wxLC. Variations of circuit inductors caused by the fabrication processes are discussed. Magnetic flux trapping in ground plane moats and its coupling to nearby inductors are discussed for circuit cooling in a residual field of several configurations.

A Comprehensive 6A Framework for Improving Patient Self-Management of Hypertension Using mHealth Services: Qualitative Thematic Analysis.

BackgroundHypertension affects over 15% of the world’s population and is a significant global public health and socioeconomic challenge. Mobile health (mHealth) services have been increasingly introduced to support hypertensive patients to improve their self-management behaviors, such as adherence to pharmacotherapy and lifestyle modifications.ObjectiveThis study aims to explore patients’ perceptions of mHealth services and the mechanisms by which the services support them to self-manage their hypertension.MethodsA semistructured, in-depth interview study was conducted with 22 outpatients of the General Hospital of Ningxia Medical University from March to May 2019. In 2015, the hospital introduced an mHealth service to support community-dwelling outpatients with self-management of hypertension. Content analysis was conducted by following a grounded theory approach for inductive thematic extraction. Constant comparison and categorization classified the first-level codes with similar meanings into higher-level themes.ResultsThe patient-perceived mechanisms by which the mHealth service supported their self-management of hypertension were summarized as 6A: access, assessment, assistance, awareness, ability, and activation. With the portability of mobile phones and digitization of information, the mHealth service provided outpatients with easy access to assess their vital signs and self-management behaviors. The assessment results gave the patients real-time awareness of their health conditions and self-management performance, which activated their self-management behaviors. The mHealth service also gave outpatients access to assistance, which included health education and self-management reminders. Both types of assistance could also be activated by abnormal assessment results, that is, uncontrolled or deteriorating blood pressure values, discomfort symptoms, or not using the service for a long period. With its scalable use to handle any possible information and services, the mHealth service provided outpatients with educational materials to learn at their own pace. This led to an improvement in self-management awareness and ability, again activating their self-management behaviors. The patients would like to see further improvements in the service to provide more useful, personalized information and reliable services.ConclusionsThe mHealth service extended the traditional hypertension care model beyond the hospital and clinician’s office. It provided outpatients with easy access to otherwise inaccessible hypertension management services. This led to process improvement for outpatients to access health assessment and health care assistance and improved their awareness and self-management ability, which activated their hypertension self-management behaviors. Future studies can apply the 6A framework to guide the design, implementation, and evaluation of mHealth services for outpatients to self-manage chronic conditions.

Assessment of a novel activity of Acacia nilotica leaf extract for chondrogenesis induction of Mesenchymal stem cells for dental applications

BackgroundThe Dearth of the self-rejuvenation capability of cartilage tissue is one of the frequent problems encountered by the dentist and orthopedic surgeons. Acacia nilotica commonly known as (babul, thorny acacia, Egyptian acacia or thorn mimosa) has wide range of medicinal uses. The current study was carried out to investigate the herbal-based chondrogenesis inducing ability of leaves extract of A. nilotica in Mesenchymal stem cells (MSCs). PurposeTo investigate the ability of Acacia nilotica leaves extract in chondrogenesis induction from Mesenchymal stem cells Study designThe experimental were designed according to the completely randomized design (CRD). MethodsDifferent concentration of water and ethanol extract of plant leaves were tested for its inhibitory activity on HDP-SC. The HDP-SCs were stimulated to differentiate into chondrocytes in the presence of water extract of A. nilotica leaves. The study was accomplished by assessing the glycosaminoglycan (GAG), aggrecan, collagen 2α1 (Col2α1), and sox9 in the cellular matrix required for cartilage tissue formation. The MSCs revealed surface markers like CD45, CD90, CD105, and CD166 cultured on specialized chondrogenic differentiation medium in presence of leaves extract of A. nilotica. ResultsThe aqueous leaves extract showed a time-dependent increase in the concentration of glycosaminoglycan (GAG) deposition on 7th, 14th, and 21st day of incubation. The chondrogenic specific markers like aggrecan and col2α1were up-regulated from 7th to 21st days of incubation showing the highest protein expression on the 21st day. The sox9 protein was substantially enhanced on the 7th to 21thday of incubation of HDP-SC with leaves extract of A. nilotica compared to standard TGF-β inducer. ConclusionThe results demonstrate that aqueous leaves extract of A. nilotica promotes chondrogenesis of Mesenchymal stem cells. The study suggests that water leaves extract of “Babool"can be used as an alternative strategy for treatment of dental pulp through chondrogenic differentiation. A. nilotica as a source of many active secondary metabolites which may serve as potential candidates for development of novel lead compounds. This research confirmed the usefulness of this plant A. nilotica as a characteristic feature of medical plant and pharmaceutical. Further studies in the future are required to identify the role of the rest of the active compounds.

Extraction of Inductances and Spatial Distributions of Currents in a Model of Superconducting Neuron

Extraction of Inductances and Spatial Distributions of Currents in a Model of Superconducting Neuron

Closed-Form Extraction Strategy of Physically Meaningful Parameters of Small-Signal HEMT Models With Distributed Parasitic Capacitive Effects

In this article, closed-form physically consistent parameter extractions are presented for small-signal models with parasitic distributed capacitive effects. First, the effective gate-source, drain-source, and gate-drain capacitances of the device are obtained and partitioned into distributed capacitive elements. With the distributed capacitive network known, a novel closed-form inductance extraction is presented, and an original series-resistance extraction is also proposed, which takes into account the distributed nature of the parasitic capacitive effects in the device model. The proposed extraction strategy has been applied to a 1.2-mm GaN HEMT and an uncertainty analysis has been performed on the basis of artificial and real S-parameters, applying the measurement uncertainty model of a commercial vector network analyzer.

Robust Model Predictive Current Control Based on Inductance and Flux Linkage Extraction Algorithm

Two-vector model predictive current control (MPCC), which applies two vectors in a control cycle, has better steady state performance than conventional MPCC. However, two-vector MPCC needs to select two optimal vectors, calculate two current slopes and two vector working times, which have to use the inductance and the flux linkage parameter in the permanent magnet synchronous motor (PMSM) drives. Therefore, the control performance of two-vector MPCC is more influenced by the model parameter accuracy. Aiming at reducing parameter sensitivity of the two-vector MPCC method, a robust two-vector MPCC method is proposed, which can obtain accurate inductance and flux linkage information in real time based on the presented inductance extraction algorithm and the flux linkage extraction algorithm. Moreover, the proportional-integral regulator parameters of the extraction algorithms are theoretically deduced. The experiment results of the proposed method indicate that the satisfactory control performance can be achieved under the condition of the parameter mismatches.

Involving adolescents in the development of research tools for adolescent mental health in China: a qualitative research study

BackgroundThe research tools for the assessment of adolescent mental health are mostly developed for high-income settings, and are used elsewhere without linguistic or cultural modification. Youth involvement in the development of research aimed at young people is recommended by WHO, but few studies have involved young people in the design of mental health tools. In this study we aimed to develop a self-completion questionnaire to assess adolescent mental health based on perceptions of Chinese adolescents. MethodsWe did a literature search to initially identify 11 scales suitable for assessing adolescent mental health and influencing factors and help-seeking behaviour. Students from rural and urban areas, and from public and private schools in Zhejiang, Anhui, Henan, and Jiangsu provinces, China, were invited to work with researchers to develop a questionnaire. Inclusion criteria were students aged 13–20 years who were willing to be involved in the study. Students initially independently completed the draft questionnaire, and provided detailed feedback in one-to-one interviews with researchers and in focus group sessions. Researchers recorded student inputs. Analysis involved inductive summarisation and factor extraction. Ethical approval was obtained from the Medical Ethics Committee of Zhejiang University. We obtained verbal consent from the volunteers and from the parents of those younger than 18 years. FindingsFrom Feb 9, 2019, to May 16, 2019, 46 student volunteers (30 male and 16 female; mean age 16 years, SD 13–20) were recruited into our study. We finalised a self-completion questionnaire with 99 items including three psychological scales. With youth involvement, we found that standard Chinese translations of widely-used scales were not understandable. Students felt that some items would not be answered honestly, and so they were changed or removed. The students were very eager to include sensitive topics, such as suicide and self-harm, and some suggested more attention should be paid to this. At their request, questions about academic pressure were expanded, with questions on social media added, including specific questions on posting modified pictures and sharing of personal problems online. InterpretationAdolescent participation in questionnaire design improves the structure and content of tools assessing mental health, making such research tools more acceptable and understandable. FundingGlobal Health Centre of Zhejiang University.

Broadband Circuit Model for EMI Analysis of Complex Interconnection Networks in Metallic Enclosures of Arbitrary Shape

In this article, a broadband equivalent circuit was developed to model the electromagnetic behavior of complex interconnection structures in metallic casings of arbitrary geometry. Based on the eigenfunctions of the system, this model is inherently stable in the time domain due to its passivity and allows simulation by a commercial circuit simulator with arbitrary linear or nonlinear port terminations. The typically slow convergence of the circuit model is accelerated by the extraction of quasi-static inductances and capacitances and losses are considered by additional resistive elements. The presented model is validated in the frequency domain by elaborate full-wave simulations.

Accurate Calculation of Partial Inductances for the Orthogonal PEEC Formulation

The Partial Element Equivalent Circuit (PEEC) method is promising numerical technique for three-dimension electromagnetic modeling across various application fields. In the framework of the PEEC method, the partial elements modeling the magnetic and electric field coupling between elementary volumes and surfaces are computed by double-folded volume and surface integrals. Assuming the quasi-static hypothesis and an orthogonal mesh, the integrals have been computed by the analytical formulas derived in literature, which significantly reduces the computational time in comparison to the numerical integration. However, the existing analytical formulas are affected by significant numerical errors for certain PEEC structural mesh necessary to model the skin and proximity effects with a higher accuracy. To utilize the full potential of the PEEC method, the calculation of partial elements has to be carefully addressed, which has not been investigated in a comprehensive way so far. Accordingly, this paper presents a systematic accuracy analysis of the existing closed-form analytical formulas and methods for calculating the self and mutual inductances between two rectangular conductors. Additionally, a new strategy to select a proper analytical formula depending on the dimensions and positions of two conductors is proposed, which allows the mutual inductance extraction with a relative error of less than 0.1%. The new method is systematically validated on examples of 3-D dense PEEC systems using the quadruple precision arithmetic as reference.

Small-signal and noise GaAs pHEMT modeling for low noise amplifier design

Small-signal and noise GaAs pHEMT modeling techniques that include analytical extraction followed by optimization are demonstrated. The following measurement processing steps were carried out before the parameter extraction: de-embedding, data smoothing and selecting the bias mode appropriate for the extraction of parasitic resistances and inductances. A low-noise amplifier operating in 5G frequency band was designed using the resulting model. A comparison between simulation and measurements of noise factor and S-parameters of the obtained low-noise amplifier is presented.

Bone Marrow Mesenchymal Stem Cell-Derived Hepatocyte-Like Cell Exosomes Reduce Hepatic Ischemia/Reperfusion Injury by Enhancing Autophagy.

Ischemia/reperfusion (I/R) injury remains a major problem in liver transplantation. I/R causes inflammatory cytokine release, apoptosis, and necrosis. Bone marrow-mesenchymal stem cells (BM-MSCs) can differentiate into hepatocytes in vivo, and differentiation further increases when hepatocytes are damaged. Exosomes are important mediators of cellular connections. Recently, exosomes of hepatocytes have been shown to play a pivotal role in inhibiting hepatocyte apoptosis and promoting hepatocyte regeneration. Therefore, we induced MSCs to differentiate into hepatocyte-like cells and extracted their exosomes; we then injected the exosomes into a mouse hepatic I/R model through the tail vein. Simultaneously, CoCl2 was used to mimic I/R in vitro. Our data indicated that in vivo, mesenchymal stem cell-derived hepatocyte-like cell exosomes (MSC-Heps-Exo) effectively relieve hepatic I/R damage, reduce hepatocyte apoptosis, and decrease liver enzyme levels. Consistent with the in vivo results, the in vitro experiments confirmed that exosomes effectively increased hepatocyte tolerance to ischemia and reduced hepatocyte apoptosis. We thus found that autophagy enhancement may be the mechanism by which exosomes protect the liver from I/R injury. These results indicate that exosomes play a protective role in hepatic I/R, and that the use of BM-MSCs for hepatocyte induction and exosome extraction may provide a new clinical treatment method through bioengineering.

Characterization and Extraction of Power Loop Stray Inductance With SiC Half-Bridge Power Module

The power loop stray inductances of the silicon carbide (SiC) half-bridge power module (HBPM) must be included in the circuit simulation model to predict the power device switching characteristics and the power bus noise caused by the power converter. Instead of a full equivalent circuit model of the SiC HBPM, a simplified but accurate three-terminal equivalent circuit model is presented in this article. Based on the simplified model, a novel frequency-domain impedance measurement method based on the two-port network technique is proposed to extract the power loop inductances through direct measurement. By using the extracted power loop inductances of a 1.2-kV 300-A SiC HBPM, a three-terminal equivalent model of the HBPM is obtained, and its accuracy is validated by the finite element method and experiments.

An Efficient MLACA-SVD Solver for Superconducting Integrated Circuit Analysis

Inductance extraction for superconducting integrated circuits requires the accurate solution of structural current distributions. FastHenry is a well known, magnetoquasistatic solver suitable for this task. It is based upon the partial element equivalent circuit, integral equation method, with the structure discretized into hexahedral filaments. It employs the multilevel fast multipole algorithm (MLFMA) for compressed storage of the mutual inductance matrix, which accounts for most of the required memory. This MLFMA implementation is especially memory efficient, given certain approximations and algorithmic parameter choices. However, errors are introduced into the matrix representation. Here, a multilevel adaptive cross approximation solver with singular value decomposition recompression (MLACA-SVD) is presented as an alternative to FastHenry's existing MLFMA solver. MLACA-SVD compresses off-diagonal matrix blocks to a specified error tolerance, based on evaluating selected entries. Quadrature recipes are presented for guaranteed accuracy of matrix entry evaluation. Numerical results for examples of practical interest show that the MLACA-SVD memory scaling versus b (number of filaments) is practically identical to that of FastHenry's MLFMA, and is close to O(blog b). The MLACA-SVD requires less memory for the same solution accuracy, and furthermore offers complete control over matrix approximation errors. For the examples considered, it is found to be a more efficient solver. It is well suited to parallelization.

MLACA With Modified Grouping Strategy for Efficient Superconducting Circuit Analysis

Electromagnetic analysis of superconducting integrated circuits is routinely required for inductance extraction. FastHenry is a well-known, applicable magnetoquasistatic analysis tool. It is accelerated with the multilevel fast multipole algorithm (MLFMA). A multilevel adaptive cross approximation solver with singular value decomposition recompression (MLACA-SVD) was recently proposed for FastHenry, as an alternative to the MLFMA. It was found to be more efficient, with regards to accuracy versus required memory. It uses the same octree grouping as FastHenry's MLFMA. Here, two modified grouping strategies are proposed to further improve MLACA-SVD efficiency by compressing interactions between larger groups, while maintaining scaling performance consistent with valid admissibility of interactions. The strategies are denoted “shell merging” and “wall merging.” Results show that the MLACA-SVD solver with merging requires about four times less memory than FastHenry's MLFMA, for similar accuracy. Shell merging is found to be slightly superior.

Design and evaluation of SiC multichip power module with low and symmetrical inductance

Compared to silicon devices, silicon carbide (SiC) devices have much lower Coss and Qg; they can switch at much higher speed, SiC power modules are thus more sensitive to stray parameters. Large stray inductance may result in high voltage spikes and cause severe electro-magnetic interference (EMI) issues; unbalanced stray inductance may contribute to uneven current sharing between parallel devices. Low and symmetrical inductance is a necessity to fully utilise the superior characteristics of SiC devices. This paper first studies the current sharing and voltage spike mechanisms of multichip power modules (MCPMs). Stray inductance distribution, current sharing as well as voltage spikes under different direct bonded copper (DBC) layout conditions are investigated using finite element modelling software. A round symmetrical DBC layout is then proposed. Compared with conventional ones, the proposed structure is symmetrical in stray inductance distribution; thus improving the consistency among chips. To reduce the total equivalent stray inductance and tackle the voltage spike problem, this study further presents an improved 3D structure on the basis of the round symmetrical DBC. The stray inductance extraction and double pulse simulation results verify the effectiveness of the improved 3D structure in current sharing as well as voltage spike reduction.

An efficient SPICE-compatible circuit model for transmission line response excited by an electrically short dipole inside a metallic cavity

ABSTRACTFor the transmission line response excited by an electrically short dipole inside a rectangular cavity, a SPICE-compatible broadband Foster type equivalent circuit is presented. The electric field inside a cavity is represented by the eigenmode decomposition of Helmholtz equation, while the current of transmission line is expanded using the eigenmode of transmission line equation. The field-to-line coupling effect is described by the Agrawal formula. The convergence of the circuit is accelerated by the extraction of quasi-static inductances and capacitances. The validity and efficiency of the presented method is verified both in frequency and time domain. Also, the effects of lossy filling material are discussed. Besides, in order to show the aggravation effect of metallic cavity on the electromagnetic interference, the induced currents on the transmission line with and without a metallic casing are given and compared.

Maternal and neonatal wellbeing during elective C-section induced with a combination of propofol and dexmedetomidine: How effective is the placental barrier in dogs?

Anaesthetics administered during C-section (CS) can cross the placenta and the foetal blood-brain barrier contributing to distress up to neonatal mortality. Therefore, to prevent neonatal risks, sedatives and analgesics are not commonly administered to the bitch until all pups are delivered. This study aims to evaluate the effect of a new anaesthetic and analgesic protocol for elective CS in dogs, focused on both maternal and neonatal wellbeing. General anaesthesia was induced by a combination of propofol (PPF) and dexmedetomidine (DEX) and maintained with isoflurane. DEX was added to PPF in order to provide analgesia and to reduce PPF dose. Propofol and DEX concentrations in maternal blood, amniotic fluid, and placenta were correlated to maternal and neonatal parameters. Maternal pain score was assessed with Glasgow Composite Measure Pain Scale short-form. Nine healthy purebred dogs scheduled for elective CS delivered 54 pups. The 77.8% of pups were vigorous at birth and assigned to the highest Apgar score (AS). The lowest AS was recorded in pups from mothers receiving additional doses of PPF (p < 0.001). Apgar scores improved with the increase in time between induction and pups' extraction, starting from 30 min after induction (p < 0.01). This study could contribute to clarify the controversy about the optimal extraction's time of pups after induction i.e. the best time between PPF administration and birth. No bitch showed post-operative pain or required additional analgesic doses based on their pain score. Maternal blood PPF and DEX, as well as placental PPF concentrations, decreased over time (p < 0.01). Conversely, placental DEX was fair uniformly detected in littermate pups. Both PPF and DEX were not detectable in amniotic fluid. Placenta resulted an effective barrier against foetal DEX exposure, making this protocol safe, analgesic and advisable for elective CS in dogs.

Model Predictive Current Control for PMSM Drives With Parameter Robustness Improvement

In order to solve the parameter dependence problem in model predictive control, an improved model predictive current control (MPCC) method based on the incremental model for surface-mounted permanent-magnet synchronous motor drives is proposed in this paper. First, the parameter sensitivity of a conventional MPCC method is analyzed, which indicates that the parameter mismatches would cause prediction current error and inaccurate delay compensation. Therefore, an incremental prediction model is introduced in this paper to eliminate the use of permanent magnetic flux linkage in a prediction model. Among the parameter of the incremental prediction model, only inductance mismatch contributes to the prediction error, since the influence of resistance mismatch on the control performance is very small. Therefore, in order to improve the antiparameter-disturbance capability of the MPCC method, an inductance disturbance controller, which includes the inductance disturbance observer and inductance extraction algorithm, is presented to update accurate inductance information for the whole control system in real time. Finally, simulation and experimental results both show that the proposed method can effectively eliminate the influence of the parameter mismatches on the control performance and reduce the parameter sensitivity of the MPCC method.

Fingerprints mapping and biochemical sensing on smartphone by electrochemiluminescence

Electrochemiluminescence (ECL) is a kind of optical radiation process triggered by electrochemistry, which has been one of the most important strategies in analytical chemistry and biosensing. Recently, smartphone, as one of the widely-used mobile device, has provided a attractive solution as simple yet powerful sensing platform to satisfy the needs of on-site inspection. Here, ECL on smartphone was put forward for fingerprints mapping and biochemical sensing. The smartphone-based system integrated both electrochemical excitation and optical analysis by built-in functional modules “all in one phone”. Typical enhanced luminescence analysis of nicotine, quenched luminescence analysis of trinitrotoluene (TNT) demonstrated the availability of the phone-based ECL system for biochemical sensing. Furthermore, multimode imaging analysis including color induction, gray processing, and binary extraction on smartphone were used for fingerprints mapping. The grain information of fingerprints was clearly displayed on the luminescence images, even the sweat pores on fingerprints were visible to naked eyes. Finally, in situ sensing of exogenous substances on fingerprints, such as nicotine and TNT were also accomplished by the phone. Results indicated the remarkable performances of the system in ECL, especially in the fields of biochemical sensing and imaging analysis. Because fingerprints were widely used to unlock phones, the combination of fingerprints imaging and sensing on smartphone would be contributed to the development of personal medicine, public health monitoring, and mobile care testing.

Influence of Magnetic Flux Trapped in Moats on Superconducting Integrated Circuit Operation

The influence of a trapped flux quantum in a superconducting ground plane hole, called a moat, on superconducting circuit operation was analyzed. We devised a calculation model to estimate the magnetic flux threading a signal line of a superconducting integrated circuit by the trapped flux quantum in a moat placed near the signal line, by using a conventional inductance extraction tool. Assuming one flux quantum trapped in the moat, the dependence of the magnetic flux threading the signal line on the distance between the moat and the signal line were calculated. We measured the flux linkage by measuring the modulation of the I-V characteristic of a dc-SQUID with a moat near the SQUID implemented by using the 2.5 kA/cm 2 Nb standard process. The measured flux linkage agrees well with the analysis results using the devised calculation model. When the distance between the 1 μm × 10 μm moat and the SQUID, the signal line size of which corresponds to the typical inductance of an adiabatic flux quantum parametron (AQFP) is 1 μm and one flux quantum is trapped in the moat, the measured magnetic flux linkage threads the signal line was approximately 1.2% of the flux quantum. This flux linkage induces approximately 4% deterioration of the device margin of the AQFP. The devised calculation model and experimental results provide useful information for designing highly integrated future superconducting integrated circuits.