Simple wavelength pre-selection and stabilization of the single-frequency operation of a microchip laser

2013 ◽  
Vol 21 (2) ◽  
Author(s):  
A. Antończak ◽  
G. Soboń ◽  
K. Abramski
Keyword(s):  
Second Harmonic ◽  
Longitudinal Mode ◽  
Laser Cavity ◽  
Single Frequency ◽  
Simple Method ◽  
Frequency Standards ◽  
Filter Tuning ◽  
Lyot Filter ◽  
External Frequency ◽  
Selection Of

AbstractThis paper presents the concept and experimental verification of a simple method of wavelength pre-selection of a single frequency, second-harmonic generation SHG solid state laser Nd:YAG/KTP with the Lyot filter. Apart from well-known configuration of single-frequency operation, the Lyot filter to stabilization of the wavelength was used. The idea presented is based on a measurement of the losses introduced by the Lyot filter inside the laser cavity, or the maximums of laser output power as a measure of the assessment of the Lyot filter tuning to a required laser longitudinal mode, not requiring any external frequency standards. This method allows for the synthesization and stabilization of a selected wavelength from the spectrum range of the gain curve of the laser with the period determined by the “Lyot comb”. In the developed system 15 values of wavelength spaced at about 32 pm (∼ 7.9 GHz) for the infrared radiation were obtained.

scholarly journals Study of the Effects of Cavity Mode Spacing on Mode-Hopping in III–V/Si Hybrid Photonic Crystal Lasers

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 848
Author(s):  
Praveen K. J. Singaravelu ◽  
Sharon M. Butler ◽  
Robert N. Sheehan ◽  
Alexandros A. Liles ◽  
Stephen P. Hegarty ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Cavity Mode ◽  
Longitudinal Mode ◽  
Laser Cavity ◽  
Threshold Current ◽  
Optical Amplifier ◽  
Laser Wavelength ◽  
Single Frequency ◽  
Mode Spacing ◽  
Mode Hopping

We present a design methodology for hybrid lasers to realise mode-hop free operation by controlling the cavity mode spacing. In this study, a compact hybrid photonic crystal laser (H-PhCL) was employed which allowed a reduction of the Fabry–Perot length of the laser cavity and eliminated the need for an active mode stabilisation mechanism in order to realise mode-hop free operation. The H-PhCL was formed by butt-coupling a reflective semiconductor optical amplifier (RSOA) with a two-dimensional silicon (Si) photonic crystal (PhC) cavity. Continuous stable single frequency operation with >40 dB side-mode suppression ratio (SMSR) of the laser was achieved for gain currents of up to 100 mA, i.e., up to four times the threshold current. The shorter length of the laser cavity enabled single frequency operation due to the selection of a single longitudinal mode by the PhC narrowband reflector. Various longitudinal mode spacing regimes were studied to explain the mode-hop free characteristics of the H-PhCL. The proposed hybrid laser design methodologies can be adapted to eliminate mode-hopping in laser wavelength.

scholarly journals Selection of dancer member using simple additive weighting

2018 ◽  
Vol 7 (3) ◽  
pp. 1096 ◽  
Author(s):  
Hana Adela ◽  
Kamarul Azmi Jasmi ◽  
Bushrah Basiron ◽  
Miftachul Huda ◽  
Andino Maseleno
Keyword(s):  
Community Life ◽  
Simple Method ◽  
Unitary State ◽  
Simple Additive Weighting ◽  
Selection Of

Travel and dance form in Indonesia is closely related to the development of community life, both in terms of ethnic structure and within the scope of the unitary state. This study determines the criteria for selecting dancer members and how to apply the qualified Simple method. Based on predetermined criteria is the ability to dance physical flexibility, skilled, nimble, confident, have the ability, fill out the form, and certificate of achievement. From the results obtained values then V1, V2, V3, V4, V5 is a member of a qualified dancer and has a highest value with a score of 100 which was obtained from V2. 

scholarly journals Transoperative refusion: a simple and safe method in emergency surgery

2014 ◽  
Vol 41 (4) ◽  
pp. 292-296
Author(s):  
Luiz Carlos Buarque Gusmão ◽  
Sérgio Henrique Chagas Valoes ◽  
José da Silva Leitão Neto
Keyword(s):  
Cost Benefit ◽  
Blood Transfusions ◽  
Factor V ◽  
West Nile Fever ◽  
Clotting Factors ◽  
Blood Contamination ◽  
Simple Method ◽  
Cost Benefit Ratio ◽  
The Cost ◽  
Selection Of

The objective is to reinforce the importance of blood reinfusion as a cheap, safe and simple method, which can be used in small hospitals, especially those in which there is no blood bank. Moreover, even with the use of devices that perform the collection and filtration of blood, more recent studies show that the cost-benefit ratio is much better when autologous transfusion is compared with blood transfusions, even when there is injury to hollow viscera and blood contamination. It is known that the allogeneic blood transfusion carries a number of risks to patients, among them are the coagulation disorders mediated by excess enzymes in the conserved blood, and deficiency in clotting factors, mainly the Factor V, the proacelerin. Another factor would be the risk of contamination with still unknown pathogens or that are not investigated during screening for selection of donors, such as the West Nile Fever and Creutzfeldt-Jacob, better known as "Mad Cow" disease. Comparing both methods, we conclude that blood autotransfusion has numerous advantages over heterologous transfusion, even in large hospitals. We are not against blood transfusions, just do not agree that the patient's own blood is discarded without making sure there will be enough blood in stock to get him out of the hemorrhagic shock.

scholarly journals A multi-site cutting device implements efficiently the divide-and-conquer strategy in tumor sampling

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 1587 ◽  
Author(s):  
Jose I. Lopez ◽  
Jesus M. Cortes
Keyword(s):  
Synthetic Data ◽  
Daily Practice ◽  
Divide And Conquer ◽  
Intratumor Heterogeneity ◽  
Pathology Laboratory ◽  
Simple Method ◽  
French Fry ◽  
Histological Processing ◽  
Tumor Sampling ◽  
Selection Of

We recently showed that in order to detect intra-tumor heterogeneity a Divide-and-Conquer (DAC) strategy of tumor sampling outperforms current routine protocols. This paper is a continuation of this work, but here we focus on DAC implementation in the Pathology Laboratory. In particular, we describe a new simple method that makes use of a cutting grid device and is applied to clear cell renal cell carcinomas for DAC implementation. This method assures a thorough sampling of large surgical specimens, facilitates the demonstration of intratumor heterogeneity, and saves time to pathologists in the daily practice. The method involves the following steps: 1. Thin slicing of the tumor (by hand or machine), 2. Application of a cutting grid to the slices (e.g., a French fry cutter), resulting in multiple tissue cubes with fixed position within the slice, 3. Selection of tissue cubes for analysis, and finally, 4. Inclusion of selected cubes into a cassette for histological processing (with about eight tissue fragments within each cassette). Thus, using our approach in a 10 cm in-diameter-tumor we generate 80 tumor tissue fragments placed in 10 cassettes and, notably, in a tenth of time. Eighty samples obtained across all the regions of the tumor will assure a much higher performance in detecting intratumor heterogeneity, as proved recently with synthetic data.

scholarly journals Modeling Features of a Single Phase-to-Earth Fault in a Medium Voltage Overhead Transmission Line

2020 ◽  
Vol 4 (2) ◽  
pp. 127-138
Author(s):  
Ismael Saeed ◽  
Kamal Sheikhyounis
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Single Phase ◽  
Single Frequency ◽  
Mathematical Representation ◽  
Medium Voltage ◽  
Overhead Transmission Line ◽  
Earth Fault ◽  
Distributed Parameters ◽  
Selection Of

The modeling and calculation of a single phase-to-earth fault of 6 to 35 kV have specific features when compared with circuits with higher nominal voltages. In this paper, a mathematical analysis and modeling of a 3-phase overhead transmission line with distributed parameters consisting of several nominal T-shaped, 3-phase links with concentrated parameters replaced by 1 nominal T-shaped link were carried out. Further analysis showed that not accounting for the distributed nature of the line parameters did not cause significant errors in the assessment of the maximum overvoltage in the arc suppression in single phase-to-earth faults, and that sufficient accuracy insures the representation of the line by only 1 nominal T-shaped, 3-phase link. Such a modeling technique makes it impossible to identify the location of single-phase faults, which is the property of higher harmonic amplification of individual frequencies. Chain equivalent schemas with constant parameters are valid for a single frequency, thereby providing an opportunity to study the nature of the wave process by the discrete selection of parameters. Next in the mathematical representation, we consider the overhead transmission lines as lines with distributed parameters.

scholarly journals Particle Swarm Optimization Based Adaptive Kalman Filters for Fault Diagnosis of Reaction Wheels

2021 ◽  
Author(s):  
Afshin Rahimi
Keyword(s):  
Parameter Estimation ◽  
Kalman Filter ◽  
Fault Diagnosis ◽  
Fault Detection ◽  
Unscented Kalman Filter ◽  
Particle Swarm ◽  
Filter Parameter ◽  
Filter Performance ◽  
Filter Tuning ◽  
Selection Of

There has been an increasing interest in fault diagnosis in recent years, as a result of the growing demand for higher performance, efficiency, reliability and safety in control systems. A faulty sensor or actuator may cause process performance degradation, process shut down, or a fatal accident. Quick fault detection and isolation can help avoid abnormal event progression and minimize the quality and productivity offsets. In space systems specifically, space and power are limited in the satellites, which means that hardware redundancy is not very practical. If actuator faults occur, analytical redundancy techniques should be employed to determine if, where, and how the fault(s) occurred. To do so, different approaches have been developed and studied and one of the wellknown approaches in the literature is using the Kalman Filter as an observer for the purpose of parameter estimation and fault detection. The gains for the filter should be selected and the selection of the process and measurement noise statistics, commonly referred to as “filter tuning,” is a major implementation issue for the Kalman filter. This process can have a significant impact on the filter performance. In practice, Kalman filter tuning is often an ad-hoc process involving a considerable amount of time for trial and error to obtain a filter with desirable –qualitative or quantitative- performance characteristics. This thesis focuses on presenting an algorithm for automation of the selection of the gains using an evolutionary swarm intelligence based optimization algorithm (Particle Swarm) to minimize the residuals of the estimated parameters. The methodology can be applied to any filter or controller but in this thesis, an Adaptive Unscented Kalman Filter parameter estimation applied to a reaction wheel unit is used for the purpose of performance evaluation of the proposed methodology.

Prophylactic Mastectomy: An Appraisal

2013 ◽  
Vol 79 (2) ◽  
pp. 205-212
Author(s):  
Flora Zagouri ◽  
Dimosthenis T. Chrysikos ◽  
Theodoros N. Sergentanis ◽  
Georgia Giannakopoulou ◽  
Constantine G. Zografos ◽  
...  
Keyword(s):  
Prophylactic Mastectomy ◽  
Brca2 Mutation ◽  
Future Perspectives ◽  
Simple Method ◽  
Main Indication ◽  
Plastic Reconstruction ◽  
Mutation Carriers ◽  
Key Issues ◽  
Selection Of Patients ◽  
Selection Of

The main indication of prophylactic mastectomy pertains to BRCA1 or BRCA2 mutation carriers. Prophylactic mastectomy includes the simple method and the subcutaneous method. Both methods can be followed by breast plastic reconstruction either at the same time or later. This review examines key issues regarding prophylactic mastectomy: the selection of patients, its effectiveness, its limitations, convergence/divergence in existing guidelines, and future perspectives.

Sign in / Sign up

Export Citation Format

Share Document