Shaping Circuit Research Articles

Optical studies of metal ceramic cathode

Optical studies of metal ceramic cathode demonstrated that the intensity of plasma light emission of the surface of the MC plate before the current maximum was below the sensitivity threshold of the 18ELU photoelectric intensifier, despite the presence of plasma sufficient for the significant magnitude of the amplitude (up to 500 A) and growth rate of the beam current (up to 20 A/ns).This confirms that the feature of the plasma occurring on the surface of the MC plate is a large emission surface at low density, the light emission of which cannot be recorded by the photoelectric intensifier, except in cases of significant current growth and current density at small anode–cathode distances and with a trimmed MC plate.Measurements of the plasma light emission spectrum of the MC cathode showed that emission plasma is generated during discharge, both from stainless steel particles and from the ceramic base material, with traces of strongly ionized ions presumably visible. This confirms the significant impact of processes occurring precisely in the gap around the metal particles on the MC cathode operation.Studies using an electron-optical converter showed that the separation of plasma from the surface of the MC plate occurs at a rate of more than 2.5 cm/μs. It is shown that the amplitude of the pre-pulse for various high voltage pulse shaping circuits of accelerators was impact on kinetics of plasma formation and light emission on the MC cathode.

Optimization and Simulation of Virtual Experiment System of Human Sports Science Based on VR

Virtual reality technology is an emerging technology developed on the basis of information technology. It is widely used in military, medical, mining, entertainment, and other fields. Therefore, many countries have been vigorously conducting research in recent years. As one of the important components of the virtual reality system, the three-dimensional human motion tracking system is of great significance to the research of practical virtual reality systems. It introduces the measurement principle of the spatial three-dimensional coordinate dynamic measurement device and discusses in detail the ultrasonic transmission, reception, amplification, filtering, comparison, shaping circuit, and single-chip interface circuit. This paper introduces the working principle and characteristics of the virtual experiment system and gives the structure diagram, hardware schematic diagram, and software flow diagram of the system. We mainly study the method of tracking human motion by measuring the three-dimensional coordinates of the space point, which lays a good foundation for the research of the actual three-dimensional motion tracking system. At the same time, the three-dimensional human body modeling is discussed, and the interactive movement policy of the human arm is briefly introduced. It has a certain effect on the actual virtual reality human-computer interaction system.

Patternable cellulose/MWCNT laminated nanocomposites with anisotropic thermal and electrical conductivity

To construct eco-friendly materials with anisotropic thermal/electrical conductivity and designable structure and shape not only is the goal of electrical materials, but also meets the requirement of sustainable society. In this work, patternable and laminated cellulose/MWCNT nanocomposites with excellent anisotropic thermal and electrical conductivity are prepared by a scalable and eco-friendly process, including a paper-making step, assembly step and in-situ welding step. In the obtained nanocomposites, the cellulose layer acts as the insulator, and the cellulose/MWCNT layer as the electrical and thermal conductor with a special segregated MWCNT network. As a result, the in-plane and through-plane electrical conductivity of the cellulose/MWCNT nanocomposite with 22.7 wt% MWCNT are 1458 and 1.48 × 10-10 S/m, respectively, and the in-plane and through-plane thermal conductivity are 1.98 and 0.34 W·m-1·K-1, respectively. Moreover, the cellulose/MWCNT nanocomposites have high electromagnetic shielding effectiveness of 31.1 dB when the thickness is 0.9 mm, good tensile strength of 156 MPa, and high shape stability at 240 °C. More interestingly, the laminated cellulose/MWCNT materials with patterned shape and sophisticated conductive circuit can be easily fabricated to work as a special and custom-tailor electronic element, thermal management device and electric-heating anti-counterfeiting pattern. Such novel cellulose/MWCNT nanocomposites prepared by a simple, effective and scalable process exhibit a huge potential in environmentally-friendly electrical and thermal management device, electromagnetic shielding element and advanced electronic anti-counterfeiting tag.

Diversity in striatal synaptic circuits arises from distinct embryonic progenitor pools in the ventral telencephalon.

SummarySynaptic circuits in the brain are precisely organized, but the processes that govern this precision are poorly understood. Here, we explore how distinct embryonic neural progenitor pools in the lateral ganglionic eminence contribute to neuronal diversity and synaptic circuit connectivity in the mouse striatum. In utero labeling of Tα1-expressing apical intermediate progenitors (aIP), as well as other progenitors (OP), reveals that both progenitors generate direct and indirect pathway spiny projection neurons (SPNs) with similar electrophysiological and anatomical properties and are intermingled in medial striatum. Subsequent optogenetic circuit-mapping experiments demonstrate that progenitor origin significantly impacts long-range excitatory input strength, with medial prefrontal cortex preferentially driving aIP-derived SPNs and visual cortex preferentially driving OP-derived SPNs. In contrast, the strength of local inhibitory inputs among SPNs is controlled by birthdate rather than progenitor origin. Combined, these results demonstrate distinct roles for embryonic progenitor origin in shaping neuronal and circuit properties of the postnatal striatum.

Loss of α7 nicotinic acetylcholine receptors in GABAergic neurons causes sex-dependent decreases in radial glia-like cell quantity and impairments in cognitive and social behavior.

The dentate gyrus (DG) is a unique brain structure in that neurons can be generated postnatally and integrated within existing circuitry throughout life.The maturation process of these newly generated neurons (granule cells) is modulated by nicotinic acetylcholine receptors (nAChRs) through a variety of mechanisms such as neural stem pool proliferation, cell survival, signal modulation, and dendritic integration. Disrupted nAChR signaling has been implicated in neuropsychiatric and neurodegenerative disorders, potentially via alterations in DG neurogenesis. GABAergic interneurons are known to express nAChRs, predominantly the α7 subtype, and have been shown to shape development, integration, and circuit reorganization of DG granule cells. Therefore, we examined histological and behavioral effects of knocking out α7 nAChRs in GABAergic neurons. Deletion of α7 nAChRs resulted in a reduction of radial glia-like cells within the subgranular zone of the DG and a concomitant trend towards decreased immature neurons, specifically in male mice, as well as sex-dependent changes in several behaviors, including social recognition and spatial learning. Overall, these findings suggest α7 nAChRs expressed in GABAergic neurons play an important role in regulating the adult neural stem cell pool and behavior in a sex-dependent manner. This provides important insight into the mechanisms by which cholinergic dysfunction contributes to the cognitive and behavioral changes associated with neurodevelopmental and neurodegenerative disorders.

Serotonin functions as a bidirectional guidance molecule regulating growth cone motility.

The neurotransmitter serotonin has been implicated in a range of complex neurological disorders linked to alterations of neuronal circuitry. Serotonin is synthesized in the developing brain before most neuronal circuits become fully functional, suggesting that serotonin might play a distinct regulatory role in shaping circuits prior to its function as a classical neurotransmitter. In this study, we asked if serotonin acts as a guidance cue by examining how serotonin alters growth cone motility of rodent sensory neurons in vitro. Using a growth cone motility assay, we found that serotonin acted as both an attractive and repulsive guidance cue through a narrow concentration range. Extracellular gradients of 50µM serotonin elicited attraction, mediated by the serotonin 5-HT2a receptor while 100µM serotonin elicited repulsion mediated by the 5-HT1b receptor. Importantly, high resolution imaging of growth cones indicated that these receptors signalled through their canonical pathways of endoplasmic reticulum-mediated calcium release and cAMP depletion, respectively. This novel characterisation of growth cone motility in response to serotonin gradients provides compelling evidence that secreted serotonin acts at the molecular level as an axon guidance cue to shape neuronal circuit formation during development.

NGD Analysis of Turtle-Shape Microstrip Circuit

A negative group delay (NGD) design of a turtle shape circuit topology is developed in this brief. The topology is comprised of two different length transmission lines (TLs) interconnecting two identical coupled lines (CLs). The S-matrix model is established as a function of the TL and CL parameters. The group delay (GD) at the half wave frequency of the short interconnect TL is derived from the transmission coefficient. To verify the relevance of the proposed turtle circuit theory, a microstrip proof of concept was modeled, designed, simulated, fabricated, and tested. The calculated, simulated and measured results are in good agreement and confirm the turtle prototype bandpass NGD function with approximately 1.97 GHz center frequency and NGD level of approximately −1.3 ns. In addition, this passive circuit operates with very low losses less than −2.5 dB over the reflection coefficient better than −14 dB.

Digitalization of inverting filter shaping circuit for nuclear pulse signals

In the design of filter shaping circuits for nuclear pulse signals, inverting filter shaping circuits perform better than non-inverting filter shaping circuits. Because these circuits facilitate changing the phase of a pulse signal, they are widely used in processing nuclear pulse signals. In this study, the transfer functions of four types of inverting filter shaping circuits, namely the common inverting filter shaping, improved inverting filter shaping, multiple feedback low-pass filter shaping, and third-order multiple feedback low-pass filter shaping, in the Laplacian domain, are derived. We establish the numerical recursive function models and digitalize the four circuits, obtain the transfer functions in the Z domain, and analyze the filter performance and amplitude–frequency response characteristics in the frequency domain. Based on the actual nuclear pulse signal of the Si-PIN detector, we realize four types of inverting digital shaping. The results show that under the same shaping parameters, the common inverting digital shaping has better amplitude extraction characteristics, the third-order multiple feedback low-pass digital shaping has better noise suppression performance, and the multiple feedback digital shaping takes into account both pulse amplitude extraction and noise suppression performance.

Low harmonic 12-pulse rectifier with a circulating current shaping circuit

This paper proposes a four-star 12-pulse diode rectifier with a circulating current shaping circuit CCSC on the DC side to decrease the input current harmonics effectively. The type of circulating current that can eliminate the input current harmonics is analysed and its waveform parameters are derived. The effects of triangular circulating current on the harmonics of the input current are analysed, and the harmonic suppression mechanism of the triangular circulating current is revealed. This scheme has excellent harmonic suppression capability, and the capacity of CCSC is only 2.35% of output power of the 12-pulse rectifier. Thus, this scheme is cost effective for high power applications. The experimental results confirm the theoretical analysis and near sinusoidal input current is obtained.

Development of Alternating Current (AC) Line Monitoring Device for Power System Management

This work presents a study of the effect of imbalance between the supply of and demand of power from the National grid on electrical appliances. In the study, an alternating current (ac) line monitoring device was developed using arduino microcontroller to carry out the investigation. The device is a single system capable of measuring both the main frequency and nominal voltage of electricity supply. The device consists of seven major components: 12 V step-down transformer, half-wave rectifier, attenuator, wave-shaping circuit, arduino microcontroller, Liquid crystal display and micro SD card. The heart of the device is the arduino microcontroller that reads the period of the pulses from the shaping circuit and the output voltage from the scale resistor connected to the attenuator circuit in order to measure the levels frequency and voltage of the ac main source. By graphically compared the reading of the voltage obtained by the ac monitoring device with that of the standard Mastech voltmeter, it was shown that the device has a good correlation with the standard voltmeter with a deviation of ±0.21%, and this has proven that the device is capable of measuring ac voltage accurately. From the frequency test level results, it was found that the frequency measured by the device closely related to the frequency measured by the standard frequency meter. This shows that the device satisfied the requirement of the overall design. Hence, it can be used in the laboratory for demonstration and research purposes as well as in power plant industries.
 Keywords: Mains frequency, nominal voltage, half-wave rectifier, attenuator, wave-shaping circuit, Arduino microcontroller

Functionalized carbon dots on TiO2 for perovskite photovoltaics and stable photoanodes for water splitting

Various types of fluorescent carbon nanoparticles, often called carbon dots (CDs), are synthesized by different polycondensation methods: microwave irradiation, hydrothermal conditions or solution chemistry at ambient temperature with subsequent chemical functionalization. The CDs are deposited on TiO2 films to be probed as electron transport layers in perovskite photovoltaics and the anode for photoelectrochemical water splitting. Nitrogen CDs, which do not contain oxygen, lead to an increase of around 50 mV in the open circuit voltage of perovskite solar cells. All the CD types produce an improved photocurrent in water splitting, particularly CDs that are functionalized with thiol groups and butyl chains. It is demonstrated that the modified electrode is stable under continuous operation. Other electrochemical characteristics of the electrode, such as the voltammogram shape, onset potentials and open circuit potentials, remain nearly unchanged upon the deposition of CDs. Only the incident photon to current conversion efficiency improves clearly, extending the absorption range by around 20 nm towards longer wavelengths. This study provides new data about mechanisms and electrode arrangements for improving the performance of n-type semiconductors in photovoltaic cells and photoelectrochemical hydrogen production.

Design of analog circuit of photomultiplier tube array for wide field of view Cherenkov telescope array of LHAASO

The wide field of view Cherenkov telescope array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) is intended to detect atmospheric Cherenkov light or fluorescence. The photomultiplier tube (PMT) array is designed to enable atmospheric monitoring in real time and telescope calibration. This paper introduces the design of the analog circuit for the PMT array. The analog board has 16 channels, where each channel contains a shaping circuit, a high gain circuit and a low gain circuit. The shaping circuit uses a charge integrating circuit, and the amplifier module is composed of a noninverting amplifier circuit and a full differential amplifier circuit. Test results indicate that the dynamic range of the designed circuit is more than 3.2 orders of magnitude, the small signal resolution is less than 20%, the corresponding resolution of large signals is less than 4%, and the relative deviation from linearity is less than 5%. These performance indicators exceed the requirements of the project.

Electrical-Model of ADITYA-U Tokamak

An Electrical-Model is developed for ADITYA-U Tokamak to study the generation of different shapes and duration of LVs out of the total available flux, which is 0.6 Vs in positive convertor supply. Loop voltage (LV) is required to be controlled during plasma discharge to optimize and predict the breakdown of plasma, proper impurity burn-through time, plasma current magnitude and duration of the plasma as per the experimental requirement. Loop voltage waveform is governed by selecting different magnitudes of resistance values, switching time and duration of external resistance in the wave shaping primary circuit. Loop voltage control system has been modelled using simulation code (Electrical-Model). Same results have been validated with the modelling of ohmic wave shaping circuit in MATLAB-Simulink. Temporal profile of loop voltage has been incorporated for ADITYA-U Tokamak for several plasma discharges, and detailed observations and results are presented in the paper.

Construction of digital survey meter model smd-03 using atmega 8 microcontroller

Digital Survey Meter model SMD-03 has been made. The Digital Survey Meter model SMD-03 was built using the GM LND-714 as the detector, CD4011 as pulse shaping circuit, ATMEGA 8 as a counter circuit and 8x2 LCD as a display. The purpose of the construction of this digital Survey Meter SMD-03 is to develop nuclear instrumentation, especially digital survey meter, especially in improving the stability counting system. The works principle of GM detector to convert the radiation beam into electric pulses. The electrical pulses are inserted into the inverting circuit and pulse shaping circuit to invert the pulses and formed into digitals pulse. The digitals pulses then are inserted into ATMega 8 to be counted and converted into mR/h and then displayed on the 8x2 LCD, measurement range : 0 – 30 mR/h. This instrument is equipped with a buzzer as a sound indicator, this activity includes the manufacture of hardware and software and testing. From the DC high voltage stability test the value of high voltage instability is 0.1%, and from the test results shows the counting linearity value R2 = 1, and counting stability test/chi-square test (X2) = 9.58. The data test results show that the digital survey meter model SMD-03 has been made can function properly.

A Three-Phase Single-Stage Isolated Flyback-Based PFC Converter With Leakage Energy Recovery Clamping Circuit

This article presents a three-phase single-stage isolated flyback-based power factor correction (PFC) converter with a clamping circuit to recover the transformer leakage inductance energy for more electric aircraft application. With the proposed clamping circuit, the transformers' leakage inductance energy is successfully captured in clamping capacitor, and subsequently, a constant power 28-V secondary supply is derived by using a two-switch forward converter to improve the converter overall efficiency. The converter unity power factor (UPF) operation is obtained by using the inherent resistance property of discontinuous conduction mode (DCM). Hence, the input current shaping circuit is eliminated and resulted in a single-loop control system. Thus, the converter control circuit requires only one sensor, which decreases the system cost and increases the system reliability and robustness. In addition, the converter provides fault-tolerant operation for single-phase loss. The converter is analyzed and the design equations are explained in detail. The voltage and current stress equations for all power components are derived and validated with the simulation. The novelty and the operation of the converter are demonstrated with the experimental results from a 2-kW laboratory prototype.

High-Efficiency Three-Phase Single-Stage Isolated Flyback-Based PFC Converter With a Novel Clamping Circuit

This article analyzes a three-phase single-stage isolated flyback-based power factor correction converter and presents a novel clamping circuit to capture the transformers leakage inductance energy. The converter unity power factor operation is obtained by using the inherent resistance property of discontinuous conduction mode. Thus, the input current shaping circuit is eliminated and resulted in a single-loop control system. Therefore, the converter control circuit requires only one sensor, which decreases the system cost, and also increases the system robustness to high-frequency noise. With the proposed clamping circuit, the transformers leakage inductance energy is successfully captured in clamping capacitor, and thereby, it is fed to the dc load by using an auxiliary two-switch forward converter which enhanced the overall operating efficiency of a converter. The converter detailed steady-state operation and the design considerations are presented. Each power component voltage stress expressions are derived to simplify the converter design, and the converter small-signal model is presented to help the controller design. The novelty and performance of the converter is verified by both simulation and experimentation.

A Novel Simple Differentiator Circuit Based on Carbon Nano Tube Field Effect Transistors Voltage Difference Transconductance Amplifier

: This paper brings in a new design, namely, voltage mode differentiator with an active element, Carbon Nanotube Field Effect Transistors Voltage Difference Transconductance Amplifier (CNVDTA). The circuit thus proposed needs one Carbon Nanotube Field Effect Transistors Voltage Difference Transconductance Amplifier (CNVDTA) element and a single capacitor. While fabricating IC’s in VLSI design, the proposed circuit proves more adaptable and applicable with the anticipated results. Methods: The proposed CNVDTA based voltage mode differentiator in CNFET technology was simulated at 32 nm at a voltage supply of ±0.9 V using the Cadence Virtuoso CAD tool. Results: It is also reported that the proposed circuit would function with ±0.9 V supply voltage and would also take care of the bias current of the order of 150 µA. Further, on the part of the transconductance (gm), it is electronically tunable with the help of bias current. Conclusion: The CNVDTA based differentiator has been found to be very useful in the triggering circuit of CRO’s, wave shaping circuits, power control circuits etc. It is also found useful in detecting the high-frequency components in the input signals.

Detection of Electron Radiation Pulses Generated by a Subnanosecond Accelerator

The characteristics of the electron beam generated by a subnanosecond accelerator with double sharpening in the voltage-pulse shaping circuit have been recorded. The duration of the electron-beam current pulse was 240–270 ps, the current amplitude was approximately 1.5 kА, and the maximum electron energy was approximately 0.95 MeV. The pulse-response characteristics of SPPD29k and SPPD29-02 X-ray semiconductor detectors were determined: their full widths at the half-maximum τ0.5 were approximately 320±30 and 450±30 ps, respectively.

Intelligent Access Control System Based on Acoustic Wave Communication

In this paper, the mode to convey information of the modulated signal of the project is analyzed from the waveform of the modulated signal of binary amplitude modulation. Then the feasibility of the decoding rule adopted by the project is analyzed by using the knowledge of the only decodable information theory, which proves that as long as the intervals between the high level and between the codes are distinguished, it can be unlocked by transmitting the password information through the 10KHZ sound wave by counting the number of the intervals. Then, the acoustic wave signal receiving and processing circuit is designed. After going through the amplifying circuit, the filtering circuit and the shaping circuit, the sound wave signal can be converted into a door lock code to control the lock tongue drive module to unlock.

A 100-ps Pulse Laser as a Calibration Source

We have developed a pulsed laser with a pulsewidth of 70 ps in the full-width at half-maximum as a light source for calibrating photon detectors. It has a simple electric circuit that generates short electric pulses that are applied to a laser diode. By utilizing the properties of the diode, a laser beam with a pulsewidth that is one-tenth of the applied electric pulse can be generated. Since the electric circuit is a simple shaping circuit, the pulsed laser can be generated at low cost, and the device can be made compact, occupying only a few cubic centimeters. Such short-pulsed-light sources are useful in high-energy experiments and astronomical observation as the time resolution and read-out electronics of the photon detectors are being continually advanced. The performance of this pulsed laser and its application for the calibration of photon detectors are reported in this paper.