Parallel Induction Research Articles

Why don't ventricles dilate in pseudotumor cerebri? A circuit model of the cerebral windkessel.

Pseudotumor cerebri is a disorder of intracranial dynamics characterized by elevated intracranial pressure (ICP) and chronic cerebral venous hypertension without structural abnormalities. A perplexing feature of pseudotumor is the absence of the ventriculomegaly found in obstructive hydrocephalus, although both diseases are associated with increased resistance to cerebrospinal fluid (CSF) resorption. Traditionally, the pathophysiology of ventricular dilation and obstructive hydrocephalus has been attributed to the backup of CSF due to impaired absorption, and it is unclear why backup of CSF with resulting ventriculomegaly would not occur in pseudotumor. In this study, the authors used an electrical circuit model to simulate the cerebral windkessel effect and explain the presence of ventriculomegaly in obstructive hydrocephalus but not in pseudotumor cerebri. The cerebral windkessel is a band-stop filter that dampens the arterial blood pressure pulse in the cranium. The authors used a tank circuit with parallel inductance and capacitance to model the windkessel. The authors distinguished the smooth flow of blood and CSF and the pulsatile flow of blood and CSF by using direct current (DC) and alternating current (AC) sources, respectively. The authors measured the dampening notch from ABP to ICP as the band-stop filter of the windkessel. In obstructive hydrocephalus, loss of CSF pathway volume impaired the flow of AC power in the cranium and caused windkessel impairment, to which ventriculomegaly is an adaptation. In pseudotumor, venous hypertension affected DC power flow in the capillaries but did not affect AC power or the windkessel, therefore obviating the need for adaptive ventriculomegaly. In pseudotumor, the CSF spaces are unaffected and the windkessel remains effective. Therefore, ventricles remain normal in size. In hydrocephalus, the windkessel, which depends on the flow of AC power in patent CSF spaces, is impaired, and the ventricles dilate as an adaptive process to restore CSF pathway volume. The windkessel model explains both ventriculomegaly in obstructive hydrocephalus and the lack of ventriculomegaly in pseudotumor. This model provides a novel understanding of the pathophysiology of disorders of CSF dynamics and has significant implications in clinical management.

Combined Inactivation of CTPS1 and ATR Is Synthetically Lethal to MYC-Overexpressing Cancer Cells.

Inhibition of CTPS in MYC-overexpressing cells blocks pyrimidine synthesis while maintaining ribosome synthesis activity to create an anabolic imbalance that induces replication stress, providing a new approach to selectively target MYC-driven cancer. See related commentary by Chabanon and Postel-Vinay, p. 969.

194 Why Do Ventricles Not Dilate in Pseudotumor Cerebri? A Circuit Model of Cerebral Windkessel

INTRODUCTION: Pseudotumor cerebri is characterized by elevated intracranial pressure (ICP) without ventricular dilation. The pathophysiology of pseudotumor is traditionally viewed as chronic cerebrovenous hypertension which causes impaired cerebrospinal fluid (CSF) resorption. Increased resistance to CSF absorption results in ventriculomegaly in obstructive hydrocephalus. In pseudotumor, however, lack of ventriculomegaly cannot be explained by this mechanism. In this study, we model the cerebral windkessel as a CSF pulsation absorber. We hypothesize that inability to absorb CSF pulsation diverts pulsatile energy to ventricles, causing ventriculomegaly, whereas effective CSF pulsation absorption leaves ventricles normal in size. METHODS: Cerebral windkessel is a band-pass filter considering arterial blood pressure (ABP) as input and ICP as output. We used a tank circuit with parallel inductance and capacitance to model windkessel and compare with the transfer function between ABP and ICP in normal dogs. Normal CSF dynamics were simulated by setting circuit parameters to correlate physiological recordings from dogs: frequency for heart rate, input and output voltages for ABP and ICP, and CSF and capillary resistance for resistance to pulsatile and pulseless flow, respectively. CSF path resistance was increased to simulate CSF space narrowing in hydrocephalus. Capillary resistance was increased to simulate impaired venous flow in pseudotumor. RESULTS: The circuit output shows agreement with physiological recordings, in which ICP pulse precedes ABP pulse. Windkessel is most effective at a given pulse frequency. In hydrocephalus, increased resistance to CSF flow disrupts cerebral windkessel, leading to ineffective pulse dampening and increased ICP phase lead. In pseudotumor, increased capillary resistance does not change cerebral windkessel effectiveness or ICP phase lead. CONCLUSION: The cerebral windkessel is a CSF pulsation absorber. An ineffective windkessel in hydrocephalus inhibits CSF pulsation absorption and diverts pulsatile energy to dilate ventricles, whereas an effective one in pseudotumor leaves ventricles normal. Our model of CSF dynamics emphasizes that ventricular dilation is a result of ineffective windkessel and decreased CSF pulsation absorption. This model provides a novel perspective on the pathophysiology of abnormal CSF dynamics and offers new directions for future research.

A Broadband Antenna Based on a Single CRLH TL Unit Cell and a Parasitic Strip for Sub-1GHz DVB and LTE Applications

A Broadband and slim profile antenna based-on a single composite right/left-handed transmission line unit cell and parasitic shorted strip is presented for sub-1 GHz digital video broadcasting and long-term evolution applications (470-970 MHz). It is comprised of an ungrounded coplanar waveguide that feeds a meandered strip (distributed series inductors), which is connected through capacitive coupling (series capacitance) with a virtual small ground, while an upper shorted meandered strip represents a parallel inductor. A shorted meandered strip (parasitic inductor) is added to create a third resonant frequency. A broadband operation is achieved by merging three different resonant modes frequencies (zeroth-order mode and two quarter wavelength monopole modes) to satisfy 6 dB bandwidth criterion. A prototype is constructed and measured in order to verify the achieved results. The results of reflection parameter, gain, efficiency, patterns and bandwidth efficiency product are presented, discussed, and evaluated with respect to literature. The results show that the proposed antenna is a potential candidate for recent broadband digital video broadcasting applications.

Broadband Circularly Polarized CPW-Fed Monopole Antenna with a Via-Free CRLH-TL Unit Cell

This article presents a broadband circularly polarized composite right/left-hand (CRLH) antenna. A compact microstrip line inductor and an interdigital capacitor are used to form a left-handed parallel inductor and a left-handed series capacitor. The metamaterial parameters of the series inductor and the parallel inductor are optimized. The asymmetric perturbation is introduced to excite the circularly polarized (CP) electromagnetic wave. The influence of interdigital capacitance on the electrical performance of the antenna is analyzed theoretically and experimentally. The value of CL is changed to reduce the electrical size of the antenna, and the resonant frequency of the antenna is reduced accordingly. The physical dimensions of this CPW-Fed monopole antenna are 25 mm ∗ 24 mm ∗ 1 mm. The measured 10 dB wide impedance bandwidth is 79.5%, and the measured 3 dB axial ratio (AR) bandwidth is 56.2%.

Feedforward common gate transimpedance amplifier circuit based on CMOS active inductor in parallel

Feedforward common gate transimpedance amplifier circuit based on CMOS active inductor in parallel

Analysis and Comparison of Series Resonant Converter With Embedded Filters for High Power Density DCX of Solid-State Transformer

A series resonant converter (SRC) operating as a DC transformer (DCX) is a candidate for the isolated bidirectional DC/DC converters of solid-state transformers (SSTs). However, the input/output current ripple of the SRC is relatively high, which requires bulky parallel capacitors and low-pass filters such as C/LC filters. These additional components reduce the power density. In addition, to operate an SRC as a DCX, a small resonant inductance is desired to reduce the voltage gain variation and achieve a faster transient response. To resolve these problems, a SRC with embedded filters is studied. Adding a clamping capacitor between split transformers not only significantly reduces current ripples and the harmonic components of the input/output currents but also connects resonant inductors in parallel to reduce the equivalent resonant inductance. In addition, dividing the resonant current into two split windings reduces the RMS current of the transformer. This paper presents a detailed analysis, a design methodology, and a comprehensive comparison with the conventional half-bridge CLLC converter with C/LC filters. 1-kW prototypes with a 600-V input voltage and 200-V output voltage demonstrate the superiority of the proposed converter; the second harmonic of the output current was significantly suppressed by 19.3 dB compared with that of the conventional converter with the same power density. The loss breakdown showed the proposed converter mitigated copper loss by 9.47% and eliminated the losses of the filter and DC-link capacitors. The prototype of the proposed converter had the highest efficiency of 95.4% at full-load among prototypes.

A Modified Quartz Crystal Capacitance Circuit by Using Parallel Inductance and Its Application for Microdisplacement Sensing

A Modified Quartz Crystal Capacitance Circuit by Using Parallel Inductance and Its Application for Microdisplacement Sensing

Efficient DC and AC Impedance Calculation for Arbitrary-Shape and Multilayer PDN Using Boundary Integration

This article presents an efficient methodology based on boundary integration to calculate the dc and ac impedance of power distribution networks (PDNs) for arbitrary-shape and multilayer printed circuit boards (PCBs). The proposed method adopts a boundary element method to extract inductances for the arbitrary parallel-plane shapes. Subsequently, the equivalent circuit formed by the via inductances and plane capacitances is solved using the node voltage method. By merging the parallel and serial inductances and simplifying the equivalent circuit, the computation time can be significantly reduced for a large number of vias and layers. This matrix manipulation strategy can be applied to various PCB structures without human intervention or commercial circuit solvers. Moreover, a contour integral method is employed to calculate the dc resistances for arbitrary shape and multilayer PDNs. Therefore, the wideband PDN impedance from dc to ac frequencies can be efficiently calculated through 1-D boundary integration, which can be performed more quickly than full-wave simulations. The proposed method can aid in the development of electronic design automation tools for PDN design.

Robust speed control of inverter fed parallel connected induction motors for electric vehicle traction applications

Induction motor is a very versatile machine having a variety of advantages over other types of single-phase AC motors. In the electric vehicle traction system, inverter set up was provided by parallel connection-based induction motor based on sensor. The induction motor is modelled using the estimated parameter instead of the speed sensor to analyse the speed performance characteristics. The proposed system focuses on improving the speed control of induction motors by modified PID controller. The parallel-connected induction motor is considered in this proposed work. The modified PID controller is compared with the conventional controller. The enhanced speed performance for inverter fed induction motors in parallel are analyzed under the parameter variation also in MATLAB/Simulink also compared with conventional methods.

High-Security Image Encryption Based on a Novel Simple Fractional-Order Memristive Chaotic System with a Single Unstable Equilibrium Point

Fractional-order chaotic systems have more complex dynamics than integer-order chaotic systems. Thus, investigating fractional chaotic systems for the creation of image cryptosystems has been popular recently. In this article, a fractional-order memristor has been developed, tested, numerically analyzed, electronically realized, and digitally implemented. Consequently, a novel simple three-dimensional (3D) fractional-order memristive chaotic system with a single unstable equilibrium point is proposed based on this memristor. This fractional-order memristor is connected in parallel with a parallel capacitor and inductor for constructing the novel fractional-order memristive chaotic system. The system’s nonlinear dynamic characteristics have been studied both analytically and numerically. To demonstrate the chaos behavior in this new system, various methods such as equilibrium points, phase portraits of chaotic attractor, bifurcation diagrams, and Lyapunov exponent are investigated. Furthermore, the proposed fractional-order memristive chaotic system was implemented using a microcontroller (Arduino Due) to demonstrate its digital applicability in real-world applications. Then, in the application field of these systems, based on the chaotic behavior of the memristive model, an encryption approach is applied for grayscale original image encryption. To increase the encryption algorithm pirate anti-attack robustness, every pixel value is included in the secret key. The state variable’s initial conditions, the parameters, and the fractional-order derivative values of the memristive chaotic system are used for contracting the keyspace of that applied cryptosystem. In order to prove the security strength of the employed encryption approach, the cryptanalysis metric tests are shown in detail through histogram analysis, keyspace analysis, key sensitivity, correlation coefficients, entropy analysis, time efficiency analysis, and comparisons with the same fieldwork. Finally, images with different sizes have been encrypted and decrypted, in order to verify the capability of the employed encryption approach for encrypting different sizes of images. The common cryptanalysis metrics values are obtained as keyspace = 2648, NPCR = 0.99866, UACI = 0.49963, H(s) = 7.9993, and time efficiency = 0.3 s. The obtained numerical simulation results and the security metrics investigations demonstrate the accuracy, high-level security, and time efficiency of the used cryptosystem which exhibits high robustness against different types of pirate attacks.

Rotor Position Synchronization in Central-Converter Multi-Motor Electric Actuation Systems

The aerospace industry is increasingly transitioning from hydraulic and pneumatic drives to power-electronic based drive systems for reduced weight and maintenance. Electromechanical thrust reverse actuation systems (EM-TRAS) are currently being considered as a replacement for mechanical based TRAS for future aircraft. An EM-TRAS consists of one or more power-electronic drives, electrical motors, and gear-trains that extend/retract mechanical members to produce a drag force that decelerates the aircraft upon landing. The use of a single (“central”) power electronic converter to simultaneously control a set of parallel induction machines is a potentially inexpensive and robust method for implementing EM-TRAS. However, because the electrical motors may experience different shaft torques—arising from differences in wind forces and a flexible nacelle—a method to implement rotor position synchronization in central-converter multi-motor (CCMM) architectures is needed. This paper introduces a novel method for achieving position synchronization within CCMM architecture by using closed-loop feedback of variable stator resistances in parallel induction machines. The feasibility of the method is demonstrated in several case studies using electromagnetic transient simulation on a set of parallel induction machines experiencing different load torque conditions, with the central converter implementing both voltage-based and current-based primary control strategies. The key result of the paper is that the CCMM architecture with proposed feedback control strategy is shown in these case studies to dynamically drive the position synchronization error to zero. The initial findings indicate that the CCMM architecture with induction motors may be a viable option for implementing EM-TRAS in future aircraft.

Dual-Polarized Filtering Transmitarray Antennas With Low-Scattering Characteristic

A filtering transmitarray antenna (TAA) with high-gain in-band radiations at the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -band and an out-of-band low-scattering characteristic is presented in this communication. The proposed composite TAA element consists of a dual-polarized resistive sheet, a fixed bandstop frequency-selective surface (FSS) element, and an adjustable bandpass FSS element also serving as a phase shifter. The resistive element is constructed by inserting a parallel inductor–capacitor (PLC) resonant structure into the center of a lumped-resistor-loaded metallic dipole. A transparent frequency-domain window at the center operating frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{c}$ </tex-math></inline-formula> ) is created by the PLC resonance and is further shared by both FSS elements, hence allowing for high in-band transmission herein. At frequencies below or above <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{c}$ </tex-math></inline-formula> , the whole composite TAA element acts as an absorber with the bandpass or bandstop FSS elements as the ground planes for the resistive sheet, respectively. The measured results show that the composite TAA can achieve gain-filtering responses with out-of-band suppression levels ≥25 dB, ~8 dB scattering cross section (SCS) reductions in 4–7 and 14–20 GHz, and the radiation gain of 25.3 dBi simultaneously. Because of these merits, the proposed design can relieve the stress on filtering circuit designs, also offering an attractive solution in stealth technology.

A Packaged THz Shunt RF MEMS Switch With Low Insertion Loss

This paper demonstrates a packaged THz shunt capacitor micro-electromechanical systems (MEMS) switch with low insertion loss. In-line shunt switch is used to achieve a low loss in THz band, which is realized by reducing the equivalent parallel inductance of switch. The equivalent circuit of the switch is analyzed systematically, the equivalent resistance is obtained based on the skin effect of high frequency current on the conductor and the current density distribution characteristics of the conductor cross-section. The equivalent capacitance is obtained by using &#x201C;double microstrip&#x201D; characteristic impedance calculation method, and the correction factor (<inline-formula> <tex-math notation="LaTeX">$\Delta$ </tex-math></inline-formula>) is introduced to calculate the equivalent inductance accurately. By optimizing equivalent circuit parameters and switch sizes, the structure of MEMS switch with low loss and high isolation characteristics are achieved. The switch is packaged by rectangular waveguide and achieved a low insertion loss. The comparison between the switch simulation results and the equivalent circuit simulation results verify that the parameter extraction method and circuit analysis are correct. The packaged MEMS switch is measured, and the results are in an acceptable agreement with simulation, the switch is actuated under voltage of &#x007E;30V. The measured result has achieved a low insertion loss with less than &#x003C; 2dB from 220 to 280GHz, and isolation with &#x007E;16 dB from 240GHz to 320GHz in the &#x201C;down&#x201D; state.

A 12-sector space vector switching table for parallel-connecting to dual induction motors fed by matrix convertor based on direct torque control

The present study proposes an improved switching table of direct torque control (DTC) for two parallel connection induction motors fed by matrix convertor. This method is based on the mean control strategy and allows the use of all switching states of matrix convertor. These functions represent the relationship between the change rates of the torque, flux, and input power factor of motors and the output voltage vector and input current vector of the matrix convertor. The effect of matrix convertor switching states on the change rate of the torque, flux, and input power factor is established by averaging approach and is done in the four improved switching tables. Finally, the optimal switching state is chosen from the switching tables. The results show that overshoot of motors speed to following reference input is 1% of reference speed less than conventional methods and also, oscillation of motors torque is less than conventional methods. Numerical results show the effectiveness of the proposed approach and prove its reliability for industrial uses.Article HighlightsIn summary, the highlight of this research is the simultaneous control of torque and speed of two electric motors by an inverter. In such a way that even in different conditions of motors load, speed and torque follow the reference values well. Also, using the advantages of DTC algorithm and applying it to use matrix convertor are the highlights of this research.

Entosis is induced by ultraviolet radiation

SummaryEntosis is a cell death mechanism that is executed through neighbor cell ingestion and killing that occurs in cancer tissues and during development. Here, we identify JNK and p38 stress-activated kinase signaling as an inducer of entosis in cells exposed to ultraviolet (UV) radiation. Cells with high levels of stress signaling are ingested and killed by those with low levels, a result of heterogeneity arising within cell populations over time.In stressed cells, entosis occurs as part of mixed-cell death response with parallel induction of apoptosis and necrosis, and we find that inhibition of one form of cell death leads to increased rates of another. Together, these findings identify stress-activated kinase signaling as a new inducer of entosis and demonstrate cross talk between different forms of cell death that can occur in parallel in response to UV radiation.

Preparation and investigation of structure, optical, nonlinear optical and thermoelectric properties of Bi2Se3 thin film

ABSTRACT Bi2Se3 thin film was prepared using thermal evaporation . Structure and surface topography were investigated using both of Diffraction Electron Microscope (DEM) and Transmission Electron Microscope (TEM). Optical results confirmed that thin film has a direct energy gap. Moreover, the values for all of oscillating energy (Eo), dispersion energy (Ed) and ratio of the free carrier concentration on the effective mass (N/m*) were determined optically. The dielectric constant (ε\\) and tangent loss (ε\\) were calculated. The density of states (DOS) for both of valence band (Nv) and conduction band (Nc) and also position of Fermi level were determined. The nonlinear optical results such as third-order optical susceptibility (χ(3)), refractive index (n2) and absorption coefficient (βc) were determined. The influence of temperature on IV results was studied; finally the dependence of all of Dispersion factor (D), parallel inductance (Lp) and Seebeck coefficient (S) values on temperature for this film was studied.

Exogenous Methyl Jasmonate Improves Cold Tolerance with Parallel Induction of Two Cold-Regulated (COR) Genes Expression in Triticum aestivum L.

Methyl jasmonate (MJ) is an important plant growth regulator that plays a key role in tolerance to biotic and abiotic stresses. In this research, the effects of exogenous MJ on cold tolerance, photosynthesis, activity and gene expression of antioxidant enzymes, proline accumulation, and expression of cold-regulated (COR) genes in wheat seedlings under low temperature (4 °C) were investigated. Exogenous MJ treatment (1 µM) promoted wheat cold tolerance before and during cold exposure. Low temperature significantly decreased photosynthetic parameters, whereas MJ application led to their partial recovery under cold exposure. Hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels increased in response to low temperature, and this was counteracted by MJ application. Exogenous MJ significantly enhanced the activities of antioxidant enzymes and upregulated the expression of MnSOD and CAT during cold exposure. MJ application also led to enhanced proline content before 4 °C exposure, whereas the P5CS gene expression was upregulated by MJ’s presence at both normal (22 °C) and low (4 °C) temperatures. It was also shown that MJ tended to upregulate the expression of the COR genes WCS19 and WCS120 genes. We conclude that exogenous MJ can alleviate the negative effect of cold stress thus increasing wheat cold tolerance.

A family of high gain fuel cell front-end converters with low input current ripple for PEMFC power conditioning systems

Since the output voltage of the proton exchange membrane fuel cell (PEMFC) is relatively low and load-dependent, a high-performance fuel cell front-end converter is required to achieve boost and power regulation in PEMFC systems. In response, a novel family of high gain fuel cell front-end converters with low input current ripple is proposed. The proposed topologies can substantially improve the voltage gain through the expansion and combination of active switched-inductor networks and passive switched-capacitor units. The introduced interleaved parallel structure is convenient to limit the current ripple on the input side to prevent accelerated aging of fuel cells, which is another prominent advantage. Meanwhile, the converters can achieve the automatic current sharing between parallel inductors and the low voltage stress on active switches and diodes. In this paper, the fuel cell model and topology derivation of the high gain fuel cell front-end converters are first analyzed. Then, it further describes the operating mode and steady-state performance of converters under the inductor current continuous conduction mode. The comparison with other converters shows that this converter is suitable for connecting the PEMFC to the high voltage DC bus. Finally, a 200 W, 20/180 V converter prototype is implemented, and the simulation and experiment prove the theoretical correctness and validate the superior performances of the proposed converters.

Reduction of Reactive Power Waste of Inductive Electrical Appliances using Power Factor Correction

Electricity is the primary source of power in most countries including Sri Lanka, and saving or minimising the waste of it has become crucial in facing the world power crisis. Electrical power is wasted in various ways including reactive power waste due to induction and capacitance of appliances, and standby power loss. These two contribute most to the waste. This paper focuses on reducing the reactive power waste of inductive electrical appliances commonly used in home and office by increasing the power factor. An attempt was made to reduce the power waste of inductive electrical appliances by connecting a capacitor bank with a variable capacitance in parallel with the appliance. Optimal capacitance and the power factor are determined using the capacitor bank. Results indicate about 30 percent of power saving could be achieved for fluorescent tube lamps using a power factor correction. A maximum power factor of 0.93 is achieved at the capacitance value of 2.99 F. It is not possible, by this method, to increase the power factor of more capacitive equipment such as CFL bulbs and ceiling fans. In this case, power minimisation could be tried connecting inductors in parallel with the equipment. Power factor and power consumption of home electrical appliances were measured for advising the general public of high power consuming equipment, especially in stand-by mode. To attain a further reduction of power waste it is proposed to measure inductance, capacitance and resistance of appliances using Hendry, Farad and Ohm meter. Total impedance can then be calculated and the power waste could be minimised using appropriate capacitors and/or inductors. Keywords: reactive power, power factor, power waste, reactive power waste, power minimisation