Steady-state and transient thermal lens behavior in the dual beam Z-scan arrangement

2006 ◽  
Vol 3 (6) ◽  
pp. 283-287 ◽  
Author(s):  
D Lorenc ◽  
P Vojtek
1999 ◽  
Vol 13 (16) ◽  
pp. 563-576 ◽  
Author(s):  
C. V. BINDHU ◽  
S. S. HARILAL ◽  
V. P. N. NAMPOORI ◽  
C. P. G. VALLABHAN

Dual beam thermal lens technique is successfully employed for the determination of absolute fluorescence quantum yield of rhodamine 6G laser dye in different solvents. A 532 nm radiation from a Q-switched Nd:YAG laser was used for the excitation purpose. The fluorescence quantum yield values are found to be strongly influenced by environmental effects. It has been observed that fluorescence yield is greater for rhodamine 6G in ethylene glycol system than in water or in methanol. Our results also indicate that parameters like concentration of the dye solution, aggregate formation and excited state absorption affect the absolute values of fluorescence yield significantly.


1998 ◽  
Vol 07 (04) ◽  
pp. 531-538 ◽  
Author(s):  
C. V. Bindhu ◽  
S. S. Harilal ◽  
Achamma Kurian ◽  
V. P. N. Nampoori ◽  
C. P. G. Vallabhan

Dual beam transient thermal lens studies were carried out in rhodamine 6G methanol solutions using 532 nm pulses from a frequency doubled Nd:YAG laser. Analysis of thermal lens signal shows the existence of different nonlinear processes like two photon absorption and three photon absorption phenomena along with one photon absorption. Concentration of the dye in the solution has been found to influence the occurrence of the different processes in a significant way.


2021 ◽  
Vol 42 (7) ◽  
Author(s):  
J. L. Jiménez-Pérez ◽  
G. López-Gamboa ◽  
J. F. Sánchez-Ramírez ◽  
Z. N. Correa-Pacheco ◽  
A. Netzahual‑Lopantzi ◽  
...  

Author(s):  
Muhammad Abid ◽  
Javed A. Chattha ◽  
Kamran A. Khan

Performance of a bolted flange joint is characterized mainly by its ‘strength’ and ‘sealing capability’. A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. In the available published work, thermal behavior of the pipe flange joints is discussed under steady state loading with and without internal pressure and under transient loading condition without internal pressure. The present design codes also do not address the effects of steady state and thermal transient loading on the structural integrity and sealing ability. It is realized that due to the ignorance of any applied transient thermal loading, the optimized performance of the bolted flange joint can not be achieved. In this paper, in order to investigate gasketed joint’s performance i.e. joint strength and sealing capability under combined internal pressure and transient thermal loading, an extensive nonlinear finite element analysis is carried out and its behavior is discussed.


Optik ◽  
2021 ◽  
pp. 168499
Author(s):  
A. Ghanem ◽  
M.D. Zidan ◽  
M.S. EL-Daher ◽  
A. Allahham
Keyword(s):  

2002 ◽  
Vol 20 (2-4) ◽  
pp. 99-110 ◽  
Author(s):  
Achamma Kurian ◽  
Nibu A. George ◽  
Binoy Paul ◽  
V. P. N. Nampoori ◽  
C. P. G. Vallabhan

In this paper we report the use of the dual beam thermal lens technique as a quantitative method to determine absolute fluorescence quantum efficiency and concentration quenching of fluorescence emission from rhodamine 6G doped Poly(methyl methacrylate) (PMMA), prepared with different concentrations of the dye. A comparison of the present data with that reported in the literature indicates that the observed variation of fluorescence quantum yield with respect to the dye concentration follows a similar profile as in the earlier reported observations on rhodamine 6G in solution. The photodegradation of the dye molecules under cw laser excitation is also studied using the present method.


2021 ◽  
Author(s):  
Zihao Yuan ◽  
Tao Zhang ◽  
Jeroen Van Duren ◽  
Ayse K. Coskun

Abstract Lab-grown diamond heat spreaders are becoming attractive solutions compared to traditional copper heat spreaders due to their high thermal conductivity, the ability to directly bond them on silicon, and allow for an ultra-thin silicon layer. Researchers have developed various thermal models and prototypes of lab-grown diamond heat spreaders to evaluate their cooling performance and heat spreading ability. The majority of existing thermal models are built using finite-element method (FEM) based simulators such as COMSOL and ANSYS. However, such commercial simulators are computationally expensive and lead to long solution times along with large memory requirements. These limitations make commercial simulators unsuitable for evaluating numerous design alternatives or runtime scenarios for real-world high-performance processors. Because of this modeling challenge, none of the existing works have evaluated the thermal behavior of lab-grown diamond heat spreaders on real-world high-performance processors running realistic application benchmarks. Recently, we have developed a parallel compact thermal simulator, PACT, that is able to carry out fast and accurate steady-state and transient thermal simulations and can be extended to support emerging integration and cooling technologies. In this paper, we use PACT to evaluate the steady-state and transient cooling performance of lab-grown diamond heat spreaders against traditional copper heat spreaders on various real-world high-performance processors (e.g., Intel i7 6950X, IBM Power9, and PicoSoC). By using PACT with architectural performance and power simulators such as Sniper and McPAT, we are able to run transient simulations with realistic benchmarks. Simulation results show that lab-grown diamond heat spreaders achieve maximum temperature and thermal gradient reductions of up to 26.73 °C and 13.75 °C when compared to traditional copper heat spreaders, respectively. The maximum steady-state and transient simulation times of PACT for the real-world high-performance chips and realistic applications used in our experiments are 259 s and 22 min, respectively.


Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4691
Author(s):  
Jia Yu ◽  
Qingshan Zhu ◽  
Li Kong ◽  
Haoqing Wang ◽  
Hongji Zhu

This paper focuses on the problem of thermoelectric cooler waste heat recovery and utilization, and proposes taking the waste heat together with the original heat source as the input heat source of the integrated thermoelectric generation–cooling system. By establishing an analytic model of this integrated thermoelectric generation–cooling system, the steady-state and transient thermal effects of this system are analyzed. The steady-state analysis results show that the thermoelectric generator’s actual heat source is about 20% larger than the intrinsic heat source. The transient analysis results prove that the current of thermoelectric power generation and the cold end temperature of the system show a nonlinear change rate with time. The cold end temperature of the system has a maximum value. Under different intrinsic heat sources, this maximum value can be reached between 1 s and 2.5 s.


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