Trigger Device Research Articles

Comparison of Self-Gated and Prospectively Triggered Fast Low Angle Shot (FLASH) Sequences for Contrast-Enhanced Magnetic Resonance Imaging of the Liver at 9.4 T in a Rat Model of Colorectal Cancer Metastases

The aim of this study was to compare a retrospectively self-gated fast low angle shot sequence (RSG-FLASH) with a prospectively triggered fast low angle shot sequence (PT-FLASH) using an external trigger device for dynamic contrast-enhanced magnetic resonance imaging of the liver at 9.4 T in a rat model of colorectal cancer metastases. In 10 rats with hepatic metastases, we acquired an axial RSG-FLASH sequence through the liver. A FLASH sequence with prospective triggering (PT-FLASH) using an external trigger device was acquired at the same location with the same imaging parameters. After intravenous injection of 0.2 mmol/kg body weight of Gd-DTPA, alternating acquisitions of both sequences were performed at 4 consecutive time points.Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and lesion enhancement were obtained for liver tumors and parenchyma. In addition, we assessed the total acquisition times of the different imaging approaches for each acquisition, including triggering and gating. Two independent readers performed a qualitative evaluation of each sequence. Statistical analyses included paired t tests and Wilcoxon matched pairs signed rank tests. No statistically significant differences in SNR, CNR, or lesion enhancement were observed. Qualitative assessments of the sequences were comparable. However, acquisition times of PT-FLASH were significantly longer (mean [SD], 160.6 [25.7] seconds; P < 0.0001) and markedly variable (minimum, 120 seconds; maximum, 209 seconds), whereas the RSG-FLASH approach demonstrated a constant mean (SD) acquisition time of 59.0 (0) seconds. The RSG-FLASH and PT-FLASH sequences do not differ qualitatively or quantitatively regarding SNR, CNR, and lesion enhancement for magnetic resonance imaging of the liver in the rats at 9.4 T. However, the variability of acquisition times for the PT-FLASH sequences is a major factor of inconsistency, and we therefore consider this approach as inappropriate for dynamic contrast-enhanced studies with multiple-measurement time points. In contrast, the RSG-FLASH sequence represents a fast, consistent, and reproducible technique suitable for contrast-agent kinetic studies in experimental small-animal imaging of the abdomen.

Design of the Pulse Triggered by Three-Phrase Controlled Rectifier Circuit

Have designed the software and hardware formation of the six-pulse triggering device which is based on the all-controlled bridge type of Three-phase circuit of the single-chip microcomputer PIC16F877A . This new controllable silicon triggering system can show the triggering angle specifically and work steadily.

Design of high-reliability LDO with current limiting characteristics with built-in new high tolerance ESD protection circuit

This paper proposes the Low-Dropout regulator including the “load current sensing circuit”. The load current sensing circuit senses the change of the load current and then reduces the ripple of the output voltage. The load transient response characteristic of the Low-Dropout regulator is improved by this method. And this paper uses a body driven technique to enhance the current driving capability for pass transistor. The proposed circuit is simulated by HSPICE with a 0.18μm BCD process parameter. In addition, this paper enhances the reliability of IC by equipping the P-substrate triggered SCR type ESD protection device.

Arrhythmia insensitive rapid cardiac T1 mapping pulse sequence

Methods: An arrhythmia-insensitive cardiac T1 mapping pulse sequence was developed based on saturation recovery T1 weighting, which is inherently insensitive to heart rate and rhythm, and two single-shot balanced steady-state free precession image acquisitions with centric k-space ordering, where T1 calculation is inherently insensitive to T2 effects. Its performance against conventional cardiac T1 mapping based on inversion recovery (i.e., MOLLI) is compared. Phantom experiments (T1 ranging from 535 to 2123 ms) were performed with heart rate and rhythm simulated at 60 and 120 beats per minute (bpm) and arrhythmia using an external triggering device. Ten human subjects and 17 large animals were scanned precontrast and 5, 10, and 15 min after contrast agent administration. Results: Compared with the reference T1 mapping, AIR yielded lower normalized root-mean-square error than MOLLI (8% vs. 3%, respectively, at 60 bpm, 28% vs. 3%, respectively, at 120 bpm, and 22% vs. 3%, respectively, at arrhythmia). In vivo studies showed that T1 measurements made by MOLLI and AIR were strongly correlated (r 5 0.99) but in poor agreement (mean difference 5 161.8 ms, upper and lower 95% limits of agreements 5 347.5 ms and 224.0 ms). Conclusion: Our AIR pulse sequence may be clinically useful for assessment of diffuse myocardial fibrosis in patients. Magn Reson Med 000:000-000, 2012. V C 2012 Wiley Periodicals,

Arrhythmia insensitive rapid cardiac T1 mapping pulse sequence

To develop an arrhythmia-insensitive rapid (AIR) cardiac T1 mapping pulse sequence for quantification of diffuse fibrosis. An arrhythmia-insensitive cardiac T1 mapping pulse sequence was developed based on saturation recovery T1 weighting, which is inherently insensitive to heart rate and rhythm, and two single-shot balanced steady-state free precession image acquisitions with centric k-space ordering, where T1 calculation is inherently insensitive to T2 effects. Its performance against conventional cardiac T1 mapping based on inversion recovery (i.e., MOLLI) is compared. Phantom experiments (T1 ranging from 535 to 2123 ms) were performed with heart rate and rhythm simulated at 60 and 120 beats per minute (bpm) and arrhythmia using an external triggering device. Ten human subjects and 17 large animals were scanned precontrast and 5, 10, and 15 min after contrast agent administration. Compared with the reference T1 mapping, AIR yielded lower normalized root-mean-square error than MOLLI (8% vs. 3%, respectively, at 60 bpm, 28% vs. 3%, respectively, at 120 bpm, and 22% vs. 3%, respectively, at arrhythmia). In vivo studies showed that T1 measurements made by MOLLI and AIR were strongly correlated (r = 0.99) but in poor agreement (mean difference = 161.8 ms, upper and lower 95% limits of agreements = 347.5 ms and -24.0 ms). Our AIR pulse sequence may be clinically useful for assessment of diffuse myocardial fibrosis in patients.

Grip and pinch capability assessment system for children

The grip movement is essential for performing daily activities. However, the assessment of this movement is currently made subjectively, due to the lack of appropriate quantification equipment. The objective of this study was to develop, validate and test a virtual environment controlled by five trigger devices used to analyse cylindrical, spherical and hook grips as well as tip-to-tip pinch and pulp-to-side movements. Sensors and electronic circuits that detect the correct grip, the threshold of grip strength and the range of motion were inserted into the devices. To validate this system, tests were conducted with 20 children while being evaluated by three physical therapists, all specialists in neurology. The results from the evaluators and the system agreed to an extent of 86.6%. Following validation, the system was used by 35 children with no motor impairment and by 10 children with mild motor abnormalities in an upper limb; these assessments provided efficient and reliable results. The developments presented in this study may help to assess grip and pinch movements and facilitate the choice of strategies in therapeutic processes.

An Active Triggered Surge Protective Gap

A triggered surge protective device is designed and its discharge characteristics are studied. The experimental results show that the triggered surge protective device has excellent surge protective characteristics. When the gap distance is 5 mm, p · d is 90 Pa·mm and without an active energy trigger circuit, the DC breakdown voltage of the triggered surge protective device is 2.32 kV and the pulse breakdown voltage is 5.75 kV. Therefore, the pulse voltage ratio, which is defined as the specific value of pulse breakdown voltage and DC breakdown voltage, is 2.48. With a semiconductor ZnO flashover trigger device and an active energy coupling trigger circuit, the pulse breakdown voltage can be reduced to 3.32 kV, the pulse voltage ratio is 1.43 and the response time is less than 100 ns. These results are helpful in laying a theoretical foundation for further studies on triggered surge protective devices.

An Intelligent Trigger Device for Photographing in Mechanical Tests of Materials

An Intelligent Trigger Device for Photographing in Mechanical Tests of Materials

Two-stage trigger silicon-controller rectifier (SCR) for radio-frequency (RF) input and output protections in nanometer technologies

In this paper, a two-stage trigger (TST) scheme is proposed to implement a low-capacitance and zero-ohm input resistance electrostatic-discharge (ESD) protection device for nanometer technology applications. Besides the main trigger device diode string, the output transistor can also be used as the trigger device. The dimension of the main trigger device can be reduced for minimizing its capacitance with the additional trigger device. Moreover, the output transistor can be as the driving device without any series resistor. This is because the diode string can help to prevent integrated circuits (ICs) from ESD damage before the primary ESD protection device turns on.

Design of Triggering Device for VFTO Measurement System

Very fast transient overvoltage (VFTO) can be generated during the operation of disconnect switch (DS). Especially in ultra high voltage (UHV) gas insulated substation (GIS), VFTO is a threat to the safety of the power system equipment. It is very important to measure VFTO waveforms accurately. VFTO waveforms are comprised of high frequency voltage superimposed on the power frequency voltage in source side of DS and high frequency voltage superimposed on step-wise voltage in load side. How to trigger oscilloscope to acquire data is a big problem in measuring process. According to the features of VFTO waveforms, new triggering device consisting of a high pass filter is designed. The output of measurement sensor is used as the input of the high pass filter, and the output of the high pass filter is used to trigger oscilloscope. When the DS is not operated, there are no signals output from the high pass filter and the oscilloscope is waiting for trigger. After the operation of DS, the high frequency signals will pass the filter to trigger oscilloscope to acquire data. The device can guarantee the oscilloscope to complete a data acquisition properly.

Note: Optical trigger device with sub-picosecond timing jitter and stability

We are presenting the design, construction, and overall performance of the optical trigger device. This device generates an electrical signal synchronously to the detected ultra-short optical pulse. The device was designed for application in satellite laser ranging and laser time transfer experiments, time correlated photon counting and similar experiments, where picosecond timing resolution and detection delay stability are required. It consists of the ultrafast optical detector, signal discriminator, output pulse forming circuit, and output driver circuits. It was constructed as a single compact device to optimize their matching and maintain stability. The detector consists of an avalanche photodiode--both silicon and germanium types may be used to cover the wavelength range of 350-1550 nm. The analogue signal of this photodiode is sensed by the ultrafast comparator with 8 GHz bandwidth. The ps clock distribution circuit is used to generate the fast rise/fall time output pulses of pre-set length. The trigger device timing performance is excellent: the random component of the timing jitter is typically 880 fs, the temperature dependence of the detection delay was measured to be 370 fs/K. The systematic error contribution depends on the laser used and its stability. The sub-ps values have been obtained for various laser sources.

2A2-O02 消費エネルギーを考慮した全方向跳躍移動機構の開発(特殊移動ロボット(2))

We presents the design and implementation process of one-time-use leaping mechanism for relocating energy-constrained sensor nodes. Towards its practical use, our focus is placed on how to realize a controllable locomotion mechanism that utilizes the ground reaction force generated. Specifically, our challenge lies in providing a practically reliable solution for a leaper triggering device which retains the pre-compressed actuators and selectively releases them. What is the most important aspect from the practical point of view is to examine whether the arbitrarily selected pre-compressed actuators can be self-triggered individually or in groups simultaneously, resulting in controlling the leaping distance and direction. The implementation details are explained, and both simulation and experimental results show that our prototype can be considered quite satisfactory for enhancing coverage and connectivity in sensor network applications.

Performance of the Resistive Plate Chambers in the CMS experiment

Resistive Plate Chambers (RPCs) are used in the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) as a dedicated trigger device. Moreover, they contribute to the muon identification and reconstruction alongside Drift Tubes and Cathode Strip Chambers. The RPC detector performance after more than one year of LHC operation is reported here.

重复频率脉冲功率系统触发器设计

重复频率脉冲功率系统触发器设计

A trigger simulation framework for the ALICE experiment

A realistic simulation of the trigger system in a complex HEP experiment is essential for performing detailed trigger efficiency studies. The ALICE trigger simulation is evolving towards a framework capable of replaying the full trigger chain starting from the input to the individual trigger processors and ending with the decision mechanisms of the ALICE central trigger processor. This paper describes the new ALICE trigger simulation framework that is being tested and deployed. The framework handles details like trigger levels, signal delays and busy signals, implementing the trigger logic via customizable trigger device objects managed by a robust scheduling mechanism. A big advantage is the high flexibility of the framework, which is able to mix together components described with very different levels of detail. The framework is being gradually integrated within the ALICE simulation and reconstruction frameworks.

Over-voltage Trigger Device for Marx Generators

For treatment of plant tissue with pulsed electric fields in large scale, synchronized operation of several Marx generators is required in order to minimize the low-field regions inside the electroporation reactor and to overcome the current limitations of a single pulse circuit. Hence, the Marx generators must be triggered. If long-term operation without service is to be achieved, these generators are triggered by over-volting the first spark gap without the use of an additional electrode for ignition, which would cause increased wear. A trigger device for over-volting the first spark gap of a Marx generator has been designed. It has been tailored to replace the charging coils between the 1 and the 2 stage of an already existing Marx generator. In order to overcome the requirements for insulation to ground potential, the trigger device is powered by the charging current of the Marx generator. This paper describes some design issues.

Research of Surge Protective Gap With Active-Energy-Coupling-Triggered Circuit

A surge protective gap (SPG) with an active energy-coupling-triggered circuit is designed, and its discharge characteristics are studied. The experimental results show that the SPG with active-energy-coupling-triggered circuit and flashover trigger device has excellent surge protective characteristics. The gap distance is 5 mm, and the produced p · d is 90 Pa · mm. Moreover, with no active-energy-coupling-triggered circuit, the dc breakdown voltage is 2.32 kV, and the pulse breakdown voltage is 5.75 kV. Therefore, the voltage ratio, which is defined as the specific value of the pulse breakdown voltage and the dc breakdown voltage, is 2.48. When using the BaTiO3 flashover trigger device and the capacitor-coupling-triggered circuit and with 5-mm gap distance and p · d = 90 Pa · mm, the pulse breakdown voltage can reduce to 2.16 kV, the voltage ratio is close to one, and the response time is less than 100 ns. The results of the study lay a theoretical foundation for further research on enhancing the voltage protection level of the SPG.

Semiself-Protection Scheme for Gigahertz High-Frequency Output ESD Protection

In this paper, a semiself-protection scheme is proposed and developed for gigahertz output electrostatic-discharge (ESD) protection. The output transistor acts as a trigger device to trigger the ESD protection device, and then, it is turned off when the ESD protection device turns on. Thus, the capacitance of a gigahertz high-frequency output pad can be minimized because this scheme is without any additional trigger device or any passive component.

Experimental Study of Electron Emission Characteristics of a Surface Flashover Trigger in a Low Pressure Environment

Characteristics of electron emission induced by a surface flashover trigger device in a low-pressure trigger switch were investigated. A test method to measure the emitted charges from the trigger device was developed, and the factors affecting the emitted charges were analyzed. The results indicated that the major emitted charges from the trigger device were induced by surface plasma generated by surface flashover occurring on the trigger dielectric material. The emitted charges and the peak emission current increased linearly with the change in the trigger voltage and bias voltage. The emitted charges collected from the anode were affected by the gap distance. However, the emitted charges were less affected by the anode diameter. Furthermore, the emitted charges and the peak emission current decreased rapidly with the increase in gas pressure in a range from 0 Pa to 100 Pa, and then remained stable or changed slightly when the increase in gas pressure up to 2400 Pa.

Experimental Study on Triggering Characteristics of a Surface Flashover Triggered Vacuum Switch

Triggering characteristics of triggered vacuum switch (TVS), including the discharge delay time, delay jitter, range of operational voltage and peak of pulsed current, are investigated. Both structure and experimental circuit of TVS are presented. The results indicate that TVS, as a surface flashover triggering device with high dielectric permittivity material, is with excellent triggering characteristics. When the hold-off voltage reaches 120 kV, the minimum operational voltage is 1.3 kV, and the minimum discharge delay time and jitter are 100 ns and ±10 ns, respectively. The peak current is up to 240 kA when the operational voltage reaches 100 kV. TVS can well satisfy the main demands of high voltage and current applications, and can also be used under a multi-crowbar circuit.