scholarly journals Pembangkitan Pulsa Orde Nanodetik Berbasis Mikrokontroler Untuk Eksitasi Transduser Ultrasonik

Author(s):  
FAATIH RIFQI MUQAFFI ◽  
BAMBANG MUKTI WIBAWA ◽  
DARMAWAN HIDAYAT

ABSTRAK Makalah ini melaporkan suatu teknik pembangkitan pulsa lebar orde nanodetik (ns) repetitif yang terprogram berbasis mikrokontroler untuk keperluan eksitasi transduser ultrasonik. Pembangkitan pulsa dan pengaturan jarak antar pulsa dilakukan melalui operasi timer mikrokontroler. Sebuah monostable multivibrator mengubah lebar pulsa dari mikrokontroler dalam orde nanodetik melalui pengaturan komponen pewaktuan resistor-kapasitor (RC) dengan cara pengaturan nilai R yang dibuat dari sebuah potensiometer digital. Hasil pengujian menunjukkan bahwa mikrokontroler membangkitkan pulsa repetitif dengan interval terprogram dalam orde 1 detik dan lebar pulsa minimum 1,25 ms. monostable multivibrator dapat mengubah lebar pulsa tersebut menjadi sekitar 140 ns. Berdasarkan hasil pengujian, dapat disimpulkan bahwa sistem berfungsi sesuai rancangan, sistem dapat membangkitkan pulsa repetitif dengan lebar pulsa hingga 140 ns dengan parameter interval dan lebar yang dapat diprogram. Kata kunci: generator pulsa, lebar pulsa singkat, mikrokontroler, monostable multivibrator, eksitasi transduser ultrasonik ABSTRACT This paper reports a repetitive, programmable, microcontroller-based pulse width generation technique for the purpose of ultrasonic transducer excitation. Pulse generation and distance adjustment between pulses is done through the microcontroller timer. A monostable multivibrator changes the pulse width of the microcontroller in the order of nanoseconds by adjusting the resistor-capacitor time constant which are done by adjusting the R value made from a digital potentiometer. The test results show that the microcontroller generates repetitive pulses with programmed intervals in order of 1 second and pulse width of 1.25 ms. A monostable multivibrator converts the pulse width to ca. 140 ns. Based on the test results, it can be concluded that the system functions according to the design as the system can generate repetitive pulses with pulse widths up to 140 nanoseconds with programmable interval and width parameters. Keywords: pulse generator, short-width pulse, microcontroller, monostable multivibrator, ultrasonic transducer excitation

2017 ◽  
Vol 94 ◽  
pp. 77-85 ◽  
Author(s):  
Zach E. Lampert ◽  
John M. Papanikolas ◽  
Simon E. Lappi ◽  
C. Lewis Reynolds

2015 ◽  
Vol 74 (8) ◽  
Author(s):  
A. A. Latiff ◽  
M. T. Ahmad ◽  
Z. Zakaria ◽  
H. Ahmad ◽  
S. W. Harun

An 1892.4 nm ultrafast passive Q-switched fiber laser is demonstrated by using Thulium-doped fiber (TDF) in conjunction with a multi-walled carbon nanotubes (MWCNTs) as a saturable absorber (SA). The MWCNTs film is sandwiched between two FC/PC fiber connectors and integrated into the laser cavity with 802 nm pump for Q-switching pulse generation. The pulse repetition rate can be tuned from 3.8 to 4.6 kHz while the corresponding pulse width reduces from 22.1 to 18.4 μs as the pump power is increased from 187.3 to 194.2 mW. A higher performance Q-switched Thulium-doped fiber laser (TDFL) is expected to be achieved with the optimization of the MWCNT-SA saturable absorber and laser cavity.


Author(s):  
Habibullah Salim ◽  
Irma Husnaini ◽  
Asnil Asnil

This research aims to make buck converter prototype for PLTS system by using fuzzy logic controller. Buck converter is required in the PLTS system if the required unidirectional voltage is smaller than the output voltage of the solar cell. Buck converter used to convert 24 Volt dc voltage to 12 Volt dc with 60 watt capability. While fuzzy logic controller is used to improve buck converter performance based on pulse generation technique for switching. The application of fuzzy logic method is expected to improve the performance of the system by maintaining the stability of buck converter output voltage of 12 volts and reduce the output ripple value. Atmega8535 microcontroller is used to generate PWM pulses for switching on power circuits. The results obtained from the test using a 100 Ohm 5 Watt load obtained the buck converter output voltage of 12.4 Volt.


2010 ◽  
Vol 22 (4) ◽  
pp. 787-790
Author(s):  
方进勇 Fang Jingyong ◽  
江伟华 Jiang Weihua ◽  
黄文华 Huang Wenhua

1973 ◽  
Vol 187 (1) ◽  
pp. 635-647 ◽  
Author(s):  
M. S. Janota ◽  
N. Watson

Today, most turbocharged diesel engines operate on the pulse system. This is most effective on those engines whose exhaust manifolds can connect groups of three cylinders to a turbine entry without scavenging interference, e.g. three-, six-, nine- and twelve-cylinder engines. However, when only two cylinders can be connected to each turbine entry, e.g. four-, eight- and sixteen-cylinder engines, without interference, the system is usually less efficient. This is because the widely fluctuating, partial admission turbine conditions lower the average turbine efficiency. Recently, the pulse converter has been developed to improve the performance of such engines. A detailed investigation into the operation and application of the pulse converter has been conducted. Test results from three completely different types of engines showed substantial improvements in performance. The dependence of the pulse converter on engine speed and load, the effect of area variations in the pulse converter and the timing of the interfering exhaust pressure waves have been studied. A comparison of theoretically predicted and measured transient pressures (from a model pulse converter fitted to a pulse generator) was made. The theoretical analysis is based on empirical steady-flow loss coefficients and forms a boundary condition for a method of characteristics analysis. Results are compared with those predicted by the simple constant-pressure theory.


1990 ◽  
Vol 45 (1) ◽  
pp. 43-49
Author(s):  
D. J. Isbister ◽  
D. H. Chaplin

AbstractThe effects of skin depth on gamma detected single pulse Nuclear Magnetic Resonance on Oriented Nuclei (NMRON) signals are theoretically explored for narrow, intermediate and broad line metallic samples, using the density matrix approach describing a pure Zeeman system. It is shown that the skin effect distortion of the signal can dominate over intermediate to broadline distortions for that range of experimental conditions generally applicable to ferromagnetic hosts. In particular, the skin effect distortions of the first maximum, obtained when the excitation pulse width is lengthened, are significant and can determine the accuracy of calibration of the radiofrequency "(rf)" field amplitude at the resonating nuclei when assigning an average turn angle to this maximum.


2017 ◽  
Vol 114 (47) ◽  
pp. E10216-E10223 ◽  
Author(s):  
Jenny Clarkson ◽  
Su Young Han ◽  
Richard Piet ◽  
Timothy McLennan ◽  
Grace M. Kane ◽  
...  

The pulsatile release of luteinizing hormone (LH) is critical for mammalian fertility. However, despite several decades of investigation, the identity of the neuronal network generating pulsatile reproductive hormone secretion remains unproven. We use here a variety of optogenetic approaches in freely behaving mice to evaluate the role of the arcuate nucleus kisspeptin (ARNKISS) neurons in LH pulse generation. Using GCaMP6 fiber photometry, we find that the ARNKISS neuron population exhibits brief (∼1 min) synchronized episodes of calcium activity occurring as frequently as every 9 min in gonadectomized mice. These ARNKISS population events were found to be near-perfectly correlated with pulsatile LH secretion. The selective optogenetic activation of ARNKISS neurons for 1 min generated pulses of LH in freely behaving mice, whereas inhibition with archaerhodopsin for 30 min suppressed LH pulsatility. Experiments aimed at resetting the activity of the ARNKISS neuron population with halorhodopsin were found to reset ongoing LH pulsatility. These observations indicate the ARNKISS neurons as the long-elusive hypothalamic pulse generator driving fertility.


2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Amit Krishna Dwivedi ◽  
Kumar Abhijeet Urma ◽  
Aminul Islam

This paper proposes a circuit capable of incorporating buffered delays in the order of picoseconds. To study our proposed circuit in the profound way, we have also explored our proposed circuit using emerging technologies such as FinFET and CNFET. Comparisons between these technologies have been made in terms of different parameters such as duration of incorporated delays (pulse width) and its variability with supply voltages. Further, this paper also proposes a trigger pulse generator by utilizing proposed buffered delay circuit as its basic element. Parametric results obtained for the proposed trigger pulse generator match different application specific requirements. These applications are also mentioned in this paper. The proposed trigger pulse generator requires very low supply voltage (700 mV) and also proves its effectiveness in terms of tunability of pulse width of the generated pulses. The modeling of the circuit has been done using Verilog and the simulation results are extensively verified using SPICE.


Sign in / Sign up

Export Citation Format

Share Document