Vivek Ranjan Sahu - Academia.edu (original) (raw)
Papers by Vivek Ranjan Sahu
Indian Journal of Dairy Science, 2021
The present study was conducted to optimize the fat content of goat milk shrikhand using goat mil... more The present study was conducted to optimize the fat content of goat milk shrikhand using goat milk with three different fat % viz. 4.0 (F1), 5.0 (F2) and 6.0 (F3) %. The pH values decreased while titratable acidity increased significantly (P<0.05) with increased fat content. Fat content and brix values increased significantly (P<0.05) with increased fat content in goat milk. All textural parameters i.e. firmness, consistency, cohesiveness and work of cohesiveness increased significantly (P<0.05) with increased fat content. Among the sensory attributes, there was no significant difference in color and appearance, texture and mouth coating scores among the treatments; however flavor, sweetness and overall acceptability scores increased significantly (P<0.05) with increased fat content. There was no significant difference between F2 and F3 for any sensory attribute including overall acceptability. Present day health conscious consumer demand product with lower fat content without compromising with taste and flavour. Therefore, F2-goat milk shrikhand prepared with 5.0% fat was found optimum and selected as the best treatment.
The Pharma Innovation, 2021
The present study was conducted to optimize the starter culture (NCDC-159) level (%) i.e. 2.0 (C1... more The present study was conducted to optimize the starter culture (NCDC-159) level (%) i.e. 2.0 (C1), 2.5(C2) and 3.0 (C3) % for preparation of goat milk shrikhand. The pH values decreased while titratable acidity increased significantly (P<0.05) with increased culture levels. Ash content of C1 whereas brix values of C2 were significantly (P<0.05) higher than other treatments. The values of all textural parameters values were significantly (P<0.05) higher in C2 than C1 and C3, whereas lightness values of C1 and C2 were significantly (P<0.05) than C3. Among the sensory attributes, flavour, texture, sweetness and overall acceptability scores of C2 were significantly (P<0.05) higher. Therefore, goat milk shrikhand prepared 2.5% NCDC-159 starter culture as found optimum.
The Pharma Innovation, 2021
The present study was conducted for development of goat milk shrikhand incorporated with apple fr... more The present study was conducted for development of goat milk shrikhand incorporated with apple fruit pulp level (%) i.e. 15 (A1), 20(A2) and 25 (A3) % for preparation of goat milk shrikhand. pH values decreased whereas titratable acidity increased significantly (P<0.05) with increased level of apple fruit pulp, however there was no significant difference between GH and A1. Among the proximate parameters, protein and fat content decreased however moisture and ash content increased significantly (P<0.05) with increased level of apple fruit pulp. All textural parameters values i.e. firmness, consistency, cohesiveness and work of cohesiveness values increased significantly (P<0.05) with increased level of apple fruit pulp; however there was no significant difference between GH and A1 for any textural parameter. The scores of all sensory attributes increased significantly (P<0.05) with increased level of apple fruit pulp in shrikhand. Overall acceptability scores of A3 were significantly (P<0.05) higher than GH, A1 and A2; however there was no significant difference between GH and A1. Therefore, A3-goat milk shrikhand with 25% apple fruit pulp was selected as the best treatment.
The Pharma Innovation, 2021
The present study was conducted to optimize the sugar level for preparation of goat milk shrikhan... more The present study was conducted to optimize the sugar level for preparation of goat milk shrikhand, which is the demand of present day health conscious consumer. Goat milk shrikhand was prepared with three different levels of sugar i.e. 20% (S1), 25% (S2) and 30% (S3) and evaluated for various physicochemical properties and sensory attributes. pH values and moisture content decreased significantly (P<0.05) whereas titratable acidity, ash content and brix values increased significantly (P<0.05) with increased sugar content in goat milk shrikhand. Textural parameters i.e. consistency, cohesiveness and work of cohesiveness values were significantly (P<0.05) higher in S2 and S3 than S1. There was no significant difference in colour parameters among the treatments. The scores of all sensory attributes increased significantly (P<0.05) with increased sugar content and S3 had significantly (P<0.05) higher flavour, sweetness, mouth coating and overall acceptability scores than S1 and S2. Therefore, S3-goat milk shrikhand prepared with 30% sugar content was found as the best treatment.
Handbook of 3D Integration, 2019
International Journal of Food, Nutrition & Dietetics, 2020
Anesthesia: Essays and Researches, 2019
Background: Laparoscopic cholecystectomy is the most commonly performed laparoscopic procedure. T... more Background: Laparoscopic cholecystectomy is the most commonly performed laparoscopic procedure. The goal of anesthetic management is to minimize stress response and early discharge. Dexmedetomidine, and pregabalin have been used successfully to attenuate laryngoscopy and intubation response in various surgical procedures. Aim: To compare efficacy of pregablin and dexmedetomidine in attenuating hemodynamic and stress response. Setting and Design: A prospective, double blind randomized trial comprising 130 ASA physical status class I and II patients posted for laparsoscopic cholecystectomy. Materials and Methods: Patients were randomized in to Group A and Group B. Group A received intravenous dexmedetomidine in a dose of 1ug.kg-1, through an infusion pump 20 min prior to induction of anaesthesia. Group B subjects received oral pregabalin 150 mg. Parameters observed were vitals, discharge time, cortisol level, side effects if any. Results: Post intervention heart rate got reduced significantly in Group A and it remained low in comparison to baseline during whole peri-operative period. In Group B, immediate post-pneumoperitoneum heart rate, and post exubation heart rate was higher than baseline. Blood pressure (BP) decreased significantly post intervention in Group A which persisted till pneumoperitoneum. In Group B there was statistically significant rise in systolic, diastolic and mean blood pressure postpneumoperitoneum as compared to baseline blood pressure. Post-operative cortisol level was significantly higher than baseline values and the level is more in Group B. Conclusion: Intravenous dexmedetomidine is more effective than oral pregabalin in attenuating perioperative stress response.
2010 14th International Heat Transfer Conference, Volume 3, 2010
A hybrid cooling scheme for thermal management of hotspots (300–500 W/cm2) in the presence of low... more A hybrid cooling scheme for thermal management of hotspots (300–500 W/cm2) in the presence of low background heat flux (100 W/cm2 over 1 cm2) is being investigated. It uses superlattice coolers (SLCs) to remove ultra high power density hotspot and microchannel heat sink for lower background heat flux. In this paper, transient response of the SLC for hotspot removal is studied. The effect of contact resistance, chip thickness, and hotspot size on the performance of the hybrid cooling scheme is also investigated.
Agricultural Reviews
With the tremendous increase in human population the demand of milk and meat is also increasing. ... more With the tremendous increase in human population the demand of milk and meat is also increasing. This necessitates the centralization of animal husbandry sector both in developed and developing countries. More production has to be taken from fewer animals which seem to be possible only with the usage of advanced technologies. Earlier this seems to be impractical due to non-availability of such technologies to the farmers. Nowadays, computational power is very cheap and easily available. Artificial intelligence is one such field of computer science devoted to creating computing machines and systems that perform operations analogous to human learning and decision-making. Artificial intelligence includes the machine learning, deep learning and predictive analytics. With the implementation of various software and algorithms, the production has been increased from the farm animals along with better management and welfare. This paper illustrates the application domains and maneuvering of ...
The Pharma Innovation Journal, 2020
India tops the livestock population in the world. Total livestock population in the country is 53... more India tops the livestock population in the world. Total livestock population in the country is 535.78 million showing an increase of 4.6% over Livestock Census-2012-the largest in the world. This is mainly because of recent advancements in frozen semen technology in India. With the advent of fluorescent microscopy, flow cytometry and advances in molecular biology, now it has become possible to evaluate the spermatozoa in terms of specific functions that are well related to fertility. However the emphasis on production of female calves is gaining popularity with a view to control the male calves’ population. Fluorescence-activated cell sorting (FACS) and immunological method of semen sexing are the two commonly used sexed semen technologies. This article provides a concise review of progress in the advancements of frozen semen technology in India along with pioneer work carried by scientists in field of animal reproduction and breeding.
Materials Characterization, 2020
Understanding of the deformation micro-mechanism as a function of grain orientation during cyclic... more Understanding of the deformation micro-mechanism as a function of grain orientation during cyclic loading is of significant importance to have failure safe design of structural components made of commercially pure titanium (CP-Ti). The evolution of deformation microstructure and texture of commercially pure titanium samples with prismatic-pyramidal (orientation A) and near basal (orientation B) as initial texture along the loading direction has been investigated during load reversal at ±8% and ±12% strain using in-situ synchrotron X-ray diffraction. The synchrotron X-ray diffraction results have been further complemented with Elastic-Plastic Self-Consistent (EPSC) simulation of the texture data and ex-situ Electron backscatter diffraction (EBSD) scan taken at the same region. Orientation A showed partially reversible texture whereas
Components Packaging and Manufacturing Technology Ieee Transactions on, Apr 1, 2014
Thermal coupling between superlattice coolers (SLCs) in an array adversely affects performance of... more Thermal coupling between superlattice coolers (SLCs) in an array adversely affects performance of an each individual cooler compared with an isolated device. Here, we have developed an electrothermal model to study this coupling between SLCs and how it is affected by geometric parameters such as separation between the superlattice structure and a ground electrode, and operating parameters such as the convective heat transfer coefficient and the activation current applied for driving the SLC. Complementary to the modeling efforts, we have also experimentally studied thermal coupling between SLCs in a microfabricated array under various conditions. Simulation results are critically compared against the experimental data and yield the conclusions of importance for an optimized design of the hybrid microfluidic SLC cooling scheme for thermal management of multiple clustered hotspots in microprocessors. We have observed more than 60% reduction in cooler performance, when placed within the few characteristic diameters of the ground electrode, due to thermal coupling effect. Thermal properties of the working fluid have even more pronounced effect on the thermal coupling between the coolers.
13th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2012
ABSTRACT We report theoretical investigation and optimization of a hot-spot cooling method. This ... more ABSTRACT We report theoretical investigation and optimization of a hot-spot cooling method. This hybrid scheme contains a liquid cooling microchannel and superlattice hotspot cooler(s). This analysis of the hybrid method aims to solve the potential thermal management challenges for hotspots especially in 3D stacked multichip packaging. The goal is to reduce the overall cooling power and optimize the energy efficiency. Starting with a generic modeling of the superlattice cooler system, the cooling temperature as a function of the superlattice thickness and the driving current is found. The analytic results are then compared with full 3D numerical simulation. The role of spreading thermal resistance in the chip substrate was found to be important. The later part of this report is the integration of the microchannel with the hotspot cooler. The pumping power is modeled based on the microchannel design and fluid properties. The total cooling power, the sum of the electrical power to pump the liquid and the electrical power to drive the superlattice cooler, is found as a function of overall heat dissipation of the chip including hotspot(s). As the goal is to keep the hottest point on the chip below certain threshold (e.g. 85°C), the result shows a dramatic reduction of the required total cooling power, when hybrid cooling scheme - superlattice hotspot cooler in conjunction with microchannel cooler - is used. Above particular analysis is based on the specific microchannel, but this proposed scheme allows us a systematic study to reduce the pump power further.
IEEE Transactions on Components, Packaging and Manufacturing Technology, 2015
A hybrid cooling scheme utilizing superlattice coolers (SLCs) along with microchannel heat sink f... more A hybrid cooling scheme utilizing superlattice coolers (SLCs) along with microchannel heat sink for thermal management of hotspots is presented. In this paper, we have studied the effect of operating and design parameters on the performance of the SLC. We have also experimentally investigated the effect of interface thermal resistance as well as thermal resistance between the ground electrode and superlattice using two test configurations: one with on-chip microchannels and another with off-chip microchannels. We demonstrated heat removal capability at the localized hotspots of more than over 300 W/cm 2 .
2012 28th Annual IEEE Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM), 2012
We report a study on a liquid-thermoelectric hybrid cooling that allows a multiple larger heat fl... more We report a study on a liquid-thermoelectric hybrid cooling that allows a multiple larger heat flux (>600 W/m 2) hotspots on a chip that is never achievable with a reasonable pump power for a microchannel with single phase liquid cooling. Thermoelectric effect is realized in this study by embedding to the silicon chip in superlattice microcooler which has been studied in our previous work. We went through an analytic modeling including spreading resistance through the substrate and modeled the fluid dynamic characteristic of microchannel so that we were able to find the pump power and cooling power of superlattice cooler. We also verified the performance with 3D numerical simulation. The results show that the hybrid system allows much higher heat flux for a hotspot while superlattice cooler locates correctly. As an example, if we have a ZT=0.5 material, a 500m x 500m hotspot can be maintained at 85 o C (ambient 35 o C) with around 850W/cm 2 while a simple liquid cooling reaches 620W/cm 2 for the same 12W/cm 2 of overall cooling power.
2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2010
Thermal management of high performance microprocessors is becoming increasingly challenging due t... more Thermal management of high performance microprocessors is becoming increasingly challenging due to the presence of hotspots. Temperature at the hotspot can be substantially greater than rest of the microprocessor, potentially compromising performance and reliability. In this paper, we have presented a hybrid cooling scheme which combines microfluidic and solidstate cooling techniques. Localized hotspot with heat flux close to 250 W/cm 2 has been successfully removed using this hybrid scheme. The effect of ambient temperature, hotspot size, and superlattice cooler electrode location is also studied.
ASME/JSME 2011 8th Thermal Engineering Joint Conference, 2011
The reduction of interfacial resistance continues to be a significant challenge in thermal manage... more The reduction of interfacial resistance continues to be a significant challenge in thermal management of semiconductor and other microscale devices. Current state-of-the-art thermal interface materials (TIMs) have resistances in the range of 5–10 mm2·K/W. At these values, particularly for the emerging highly nonhomogeneous materials, standard measurement techniques often fail to provide accurate results. This paper describes the use of infrared microscopy for measuring the total thermal resistance across multiple interfaces. The method is capable of measuring samples of wide ranging resistances with thicknesses ranging from 50–250 μm. This steady-state technique has several advantages over other methods, including the elimination of the need for intrusive temperature monitoring devices like thermocouples at the area of interest and the need for a priori knowledge of the specific heat and density of the materials of interest, as in the transient techniques for determining thermal res...
Journal of Electronic Packaging, 2014
Power dissipated by modern microprocessors is a function of time and continuously changes with th... more Power dissipated by modern microprocessors is a function of time and continuously changes with the workload, giving rise to temporal hotspots of local areas with very high power dissipation. A hybrid cooling scheme has been proposed, which combines solid-state cooling to remove the dynamically changing hotspots in real time while addressing the steady-state background power dissipation using liquid cooling in embedded microchannels. In this paper, we have investigated the transient behavior of the hybrid scheme through experiments as well as computational modeling. Infrared microscopy, equipped with transient detector, was used to study the transient cooling behavior when a power spike is produced by a microfabricated heater, emulating a hot spot. The results indicate that solid-state superlattice cooling (SLC) offers an extremely fast transient response, having time constant of the order of few tens of microseconds which matches with dynamics of microprocessor power dissipation. Th...
Indian Journal of Dairy Science, 2021
The present study was conducted to optimize the fat content of goat milk shrikhand using goat mil... more The present study was conducted to optimize the fat content of goat milk shrikhand using goat milk with three different fat % viz. 4.0 (F1), 5.0 (F2) and 6.0 (F3) %. The pH values decreased while titratable acidity increased significantly (P<0.05) with increased fat content. Fat content and brix values increased significantly (P<0.05) with increased fat content in goat milk. All textural parameters i.e. firmness, consistency, cohesiveness and work of cohesiveness increased significantly (P<0.05) with increased fat content. Among the sensory attributes, there was no significant difference in color and appearance, texture and mouth coating scores among the treatments; however flavor, sweetness and overall acceptability scores increased significantly (P<0.05) with increased fat content. There was no significant difference between F2 and F3 for any sensory attribute including overall acceptability. Present day health conscious consumer demand product with lower fat content without compromising with taste and flavour. Therefore, F2-goat milk shrikhand prepared with 5.0% fat was found optimum and selected as the best treatment.
The Pharma Innovation, 2021
The present study was conducted to optimize the starter culture (NCDC-159) level (%) i.e. 2.0 (C1... more The present study was conducted to optimize the starter culture (NCDC-159) level (%) i.e. 2.0 (C1), 2.5(C2) and 3.0 (C3) % for preparation of goat milk shrikhand. The pH values decreased while titratable acidity increased significantly (P<0.05) with increased culture levels. Ash content of C1 whereas brix values of C2 were significantly (P<0.05) higher than other treatments. The values of all textural parameters values were significantly (P<0.05) higher in C2 than C1 and C3, whereas lightness values of C1 and C2 were significantly (P<0.05) than C3. Among the sensory attributes, flavour, texture, sweetness and overall acceptability scores of C2 were significantly (P<0.05) higher. Therefore, goat milk shrikhand prepared 2.5% NCDC-159 starter culture as found optimum.
The Pharma Innovation, 2021
The present study was conducted for development of goat milk shrikhand incorporated with apple fr... more The present study was conducted for development of goat milk shrikhand incorporated with apple fruit pulp level (%) i.e. 15 (A1), 20(A2) and 25 (A3) % for preparation of goat milk shrikhand. pH values decreased whereas titratable acidity increased significantly (P<0.05) with increased level of apple fruit pulp, however there was no significant difference between GH and A1. Among the proximate parameters, protein and fat content decreased however moisture and ash content increased significantly (P<0.05) with increased level of apple fruit pulp. All textural parameters values i.e. firmness, consistency, cohesiveness and work of cohesiveness values increased significantly (P<0.05) with increased level of apple fruit pulp; however there was no significant difference between GH and A1 for any textural parameter. The scores of all sensory attributes increased significantly (P<0.05) with increased level of apple fruit pulp in shrikhand. Overall acceptability scores of A3 were significantly (P<0.05) higher than GH, A1 and A2; however there was no significant difference between GH and A1. Therefore, A3-goat milk shrikhand with 25% apple fruit pulp was selected as the best treatment.
The Pharma Innovation, 2021
The present study was conducted to optimize the sugar level for preparation of goat milk shrikhan... more The present study was conducted to optimize the sugar level for preparation of goat milk shrikhand, which is the demand of present day health conscious consumer. Goat milk shrikhand was prepared with three different levels of sugar i.e. 20% (S1), 25% (S2) and 30% (S3) and evaluated for various physicochemical properties and sensory attributes. pH values and moisture content decreased significantly (P<0.05) whereas titratable acidity, ash content and brix values increased significantly (P<0.05) with increased sugar content in goat milk shrikhand. Textural parameters i.e. consistency, cohesiveness and work of cohesiveness values were significantly (P<0.05) higher in S2 and S3 than S1. There was no significant difference in colour parameters among the treatments. The scores of all sensory attributes increased significantly (P<0.05) with increased sugar content and S3 had significantly (P<0.05) higher flavour, sweetness, mouth coating and overall acceptability scores than S1 and S2. Therefore, S3-goat milk shrikhand prepared with 30% sugar content was found as the best treatment.
Handbook of 3D Integration, 2019
International Journal of Food, Nutrition & Dietetics, 2020
Anesthesia: Essays and Researches, 2019
Background: Laparoscopic cholecystectomy is the most commonly performed laparoscopic procedure. T... more Background: Laparoscopic cholecystectomy is the most commonly performed laparoscopic procedure. The goal of anesthetic management is to minimize stress response and early discharge. Dexmedetomidine, and pregabalin have been used successfully to attenuate laryngoscopy and intubation response in various surgical procedures. Aim: To compare efficacy of pregablin and dexmedetomidine in attenuating hemodynamic and stress response. Setting and Design: A prospective, double blind randomized trial comprising 130 ASA physical status class I and II patients posted for laparsoscopic cholecystectomy. Materials and Methods: Patients were randomized in to Group A and Group B. Group A received intravenous dexmedetomidine in a dose of 1ug.kg-1, through an infusion pump 20 min prior to induction of anaesthesia. Group B subjects received oral pregabalin 150 mg. Parameters observed were vitals, discharge time, cortisol level, side effects if any. Results: Post intervention heart rate got reduced significantly in Group A and it remained low in comparison to baseline during whole peri-operative period. In Group B, immediate post-pneumoperitoneum heart rate, and post exubation heart rate was higher than baseline. Blood pressure (BP) decreased significantly post intervention in Group A which persisted till pneumoperitoneum. In Group B there was statistically significant rise in systolic, diastolic and mean blood pressure postpneumoperitoneum as compared to baseline blood pressure. Post-operative cortisol level was significantly higher than baseline values and the level is more in Group B. Conclusion: Intravenous dexmedetomidine is more effective than oral pregabalin in attenuating perioperative stress response.
2010 14th International Heat Transfer Conference, Volume 3, 2010
A hybrid cooling scheme for thermal management of hotspots (300–500 W/cm2) in the presence of low... more A hybrid cooling scheme for thermal management of hotspots (300–500 W/cm2) in the presence of low background heat flux (100 W/cm2 over 1 cm2) is being investigated. It uses superlattice coolers (SLCs) to remove ultra high power density hotspot and microchannel heat sink for lower background heat flux. In this paper, transient response of the SLC for hotspot removal is studied. The effect of contact resistance, chip thickness, and hotspot size on the performance of the hybrid cooling scheme is also investigated.
Agricultural Reviews
With the tremendous increase in human population the demand of milk and meat is also increasing. ... more With the tremendous increase in human population the demand of milk and meat is also increasing. This necessitates the centralization of animal husbandry sector both in developed and developing countries. More production has to be taken from fewer animals which seem to be possible only with the usage of advanced technologies. Earlier this seems to be impractical due to non-availability of such technologies to the farmers. Nowadays, computational power is very cheap and easily available. Artificial intelligence is one such field of computer science devoted to creating computing machines and systems that perform operations analogous to human learning and decision-making. Artificial intelligence includes the machine learning, deep learning and predictive analytics. With the implementation of various software and algorithms, the production has been increased from the farm animals along with better management and welfare. This paper illustrates the application domains and maneuvering of ...
The Pharma Innovation Journal, 2020
India tops the livestock population in the world. Total livestock population in the country is 53... more India tops the livestock population in the world. Total livestock population in the country is 535.78 million showing an increase of 4.6% over Livestock Census-2012-the largest in the world. This is mainly because of recent advancements in frozen semen technology in India. With the advent of fluorescent microscopy, flow cytometry and advances in molecular biology, now it has become possible to evaluate the spermatozoa in terms of specific functions that are well related to fertility. However the emphasis on production of female calves is gaining popularity with a view to control the male calves’ population. Fluorescence-activated cell sorting (FACS) and immunological method of semen sexing are the two commonly used sexed semen technologies. This article provides a concise review of progress in the advancements of frozen semen technology in India along with pioneer work carried by scientists in field of animal reproduction and breeding.
Materials Characterization, 2020
Understanding of the deformation micro-mechanism as a function of grain orientation during cyclic... more Understanding of the deformation micro-mechanism as a function of grain orientation during cyclic loading is of significant importance to have failure safe design of structural components made of commercially pure titanium (CP-Ti). The evolution of deformation microstructure and texture of commercially pure titanium samples with prismatic-pyramidal (orientation A) and near basal (orientation B) as initial texture along the loading direction has been investigated during load reversal at ±8% and ±12% strain using in-situ synchrotron X-ray diffraction. The synchrotron X-ray diffraction results have been further complemented with Elastic-Plastic Self-Consistent (EPSC) simulation of the texture data and ex-situ Electron backscatter diffraction (EBSD) scan taken at the same region. Orientation A showed partially reversible texture whereas
Components Packaging and Manufacturing Technology Ieee Transactions on, Apr 1, 2014
Thermal coupling between superlattice coolers (SLCs) in an array adversely affects performance of... more Thermal coupling between superlattice coolers (SLCs) in an array adversely affects performance of an each individual cooler compared with an isolated device. Here, we have developed an electrothermal model to study this coupling between SLCs and how it is affected by geometric parameters such as separation between the superlattice structure and a ground electrode, and operating parameters such as the convective heat transfer coefficient and the activation current applied for driving the SLC. Complementary to the modeling efforts, we have also experimentally studied thermal coupling between SLCs in a microfabricated array under various conditions. Simulation results are critically compared against the experimental data and yield the conclusions of importance for an optimized design of the hybrid microfluidic SLC cooling scheme for thermal management of multiple clustered hotspots in microprocessors. We have observed more than 60% reduction in cooler performance, when placed within the few characteristic diameters of the ground electrode, due to thermal coupling effect. Thermal properties of the working fluid have even more pronounced effect on the thermal coupling between the coolers.
13th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2012
ABSTRACT We report theoretical investigation and optimization of a hot-spot cooling method. This ... more ABSTRACT We report theoretical investigation and optimization of a hot-spot cooling method. This hybrid scheme contains a liquid cooling microchannel and superlattice hotspot cooler(s). This analysis of the hybrid method aims to solve the potential thermal management challenges for hotspots especially in 3D stacked multichip packaging. The goal is to reduce the overall cooling power and optimize the energy efficiency. Starting with a generic modeling of the superlattice cooler system, the cooling temperature as a function of the superlattice thickness and the driving current is found. The analytic results are then compared with full 3D numerical simulation. The role of spreading thermal resistance in the chip substrate was found to be important. The later part of this report is the integration of the microchannel with the hotspot cooler. The pumping power is modeled based on the microchannel design and fluid properties. The total cooling power, the sum of the electrical power to pump the liquid and the electrical power to drive the superlattice cooler, is found as a function of overall heat dissipation of the chip including hotspot(s). As the goal is to keep the hottest point on the chip below certain threshold (e.g. 85°C), the result shows a dramatic reduction of the required total cooling power, when hybrid cooling scheme - superlattice hotspot cooler in conjunction with microchannel cooler - is used. Above particular analysis is based on the specific microchannel, but this proposed scheme allows us a systematic study to reduce the pump power further.
IEEE Transactions on Components, Packaging and Manufacturing Technology, 2015
A hybrid cooling scheme utilizing superlattice coolers (SLCs) along with microchannel heat sink f... more A hybrid cooling scheme utilizing superlattice coolers (SLCs) along with microchannel heat sink for thermal management of hotspots is presented. In this paper, we have studied the effect of operating and design parameters on the performance of the SLC. We have also experimentally investigated the effect of interface thermal resistance as well as thermal resistance between the ground electrode and superlattice using two test configurations: one with on-chip microchannels and another with off-chip microchannels. We demonstrated heat removal capability at the localized hotspots of more than over 300 W/cm 2 .
2012 28th Annual IEEE Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM), 2012
We report a study on a liquid-thermoelectric hybrid cooling that allows a multiple larger heat fl... more We report a study on a liquid-thermoelectric hybrid cooling that allows a multiple larger heat flux (>600 W/m 2) hotspots on a chip that is never achievable with a reasonable pump power for a microchannel with single phase liquid cooling. Thermoelectric effect is realized in this study by embedding to the silicon chip in superlattice microcooler which has been studied in our previous work. We went through an analytic modeling including spreading resistance through the substrate and modeled the fluid dynamic characteristic of microchannel so that we were able to find the pump power and cooling power of superlattice cooler. We also verified the performance with 3D numerical simulation. The results show that the hybrid system allows much higher heat flux for a hotspot while superlattice cooler locates correctly. As an example, if we have a ZT=0.5 material, a 500m x 500m hotspot can be maintained at 85 o C (ambient 35 o C) with around 850W/cm 2 while a simple liquid cooling reaches 620W/cm 2 for the same 12W/cm 2 of overall cooling power.
2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2010
Thermal management of high performance microprocessors is becoming increasingly challenging due t... more Thermal management of high performance microprocessors is becoming increasingly challenging due to the presence of hotspots. Temperature at the hotspot can be substantially greater than rest of the microprocessor, potentially compromising performance and reliability. In this paper, we have presented a hybrid cooling scheme which combines microfluidic and solidstate cooling techniques. Localized hotspot with heat flux close to 250 W/cm 2 has been successfully removed using this hybrid scheme. The effect of ambient temperature, hotspot size, and superlattice cooler electrode location is also studied.
ASME/JSME 2011 8th Thermal Engineering Joint Conference, 2011
The reduction of interfacial resistance continues to be a significant challenge in thermal manage... more The reduction of interfacial resistance continues to be a significant challenge in thermal management of semiconductor and other microscale devices. Current state-of-the-art thermal interface materials (TIMs) have resistances in the range of 5–10 mm2·K/W. At these values, particularly for the emerging highly nonhomogeneous materials, standard measurement techniques often fail to provide accurate results. This paper describes the use of infrared microscopy for measuring the total thermal resistance across multiple interfaces. The method is capable of measuring samples of wide ranging resistances with thicknesses ranging from 50–250 μm. This steady-state technique has several advantages over other methods, including the elimination of the need for intrusive temperature monitoring devices like thermocouples at the area of interest and the need for a priori knowledge of the specific heat and density of the materials of interest, as in the transient techniques for determining thermal res...
Journal of Electronic Packaging, 2014
Power dissipated by modern microprocessors is a function of time and continuously changes with th... more Power dissipated by modern microprocessors is a function of time and continuously changes with the workload, giving rise to temporal hotspots of local areas with very high power dissipation. A hybrid cooling scheme has been proposed, which combines solid-state cooling to remove the dynamically changing hotspots in real time while addressing the steady-state background power dissipation using liquid cooling in embedded microchannels. In this paper, we have investigated the transient behavior of the hybrid scheme through experiments as well as computational modeling. Infrared microscopy, equipped with transient detector, was used to study the transient cooling behavior when a power spike is produced by a microfabricated heater, emulating a hot spot. The results indicate that solid-state superlattice cooling (SLC) offers an extremely fast transient response, having time constant of the order of few tens of microseconds which matches with dynamics of microprocessor power dissipation. Th...